The present application is based on, and claims priority from JP Application Serial Number 2021-038676, filed Mar. 10, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a drive method of a liquid discharging head and a liquid discharging apparatus.
JP-A-2011-37257 discloses a liquid discharging head that discharges droplets by receiving a drive signal.
However, in the related art described above, there is a possibility that the discharge performance deteriorates as the viscosity of liquid increases.
In order to solve the above problems, a drive method of a liquid discharging head according to a preferred embodiment of the present disclosure is a drive method of a liquid discharging head having a discharging portion that includes a drive element that displaces by being supplied with drive signals that include a first drive signal and a second drive signal, a pressure chamber inside which pressure is increased or decreased according to a displacement of the drive element, and a nozzle configured to communicate with the pressure chamber to discharge liquid, which fills inside the pressure chamber, as a droplet in a discharging direction according to an increase or a decrease in the pressure inside the pressure chamber, the drive method including: a first step of acquiring physical property information indicating a physical property of liquid in the liquid discharging head; a second step of determining a waveform of the drive signal based on the physical property information; a third step of forming a first liquid column in which a liquid surface inside the discharging portion protrudes in the discharging direction by supplying a first waveform, which is included in the first drive signal among the drive signals having the waveforms determined in the second step, to the drive element; and a fourth step of, when the first liquid column is formed, forming a second liquid column in which a liquid surface inside the discharging portion protrudes in the discharging direction by supplying a second waveform, which is included in the second drive signal among the drive signals having the waveforms determined in the second step, to the drive element, and thereafter discharging a part or all of liquid constituting the second liquid column as a droplet.
Further, in order to solve the above problems, a liquid discharging apparatus according to a preferred embodiment of the present disclosure is a liquid discharging apparatus including: a liquid discharging head having a discharging portion that includes a drive element that displaces by being supplied with drive signals that include a first drive signal and a second drive signal, a pressure chamber inside which pressure is increased or decreased according to a displacement of the drive element, and a nozzle configured to communicate with the pressure chamber to discharge liquid, which fills inside the pressure chamber, as a droplet in a discharging direction according to an increase or a decrease in the pressure inside the pressure chamber; and a control portion controlling the liquid discharging head, in which the control portion acquires physical property information indicating a physical property of liquid in the liquid discharging head, determines a waveform of the drive signal based on the physical property information, forms a first liquid column in which a liquid surface inside the discharging portion protrudes in the discharging direction by supplying a first waveform, which is included in the first drive signal among the drive signals having the waveforms determined by the control portion, to the drive element, and when the first liquid column is formed, forms a second liquid column in which a liquid surface inside the discharging portion protrudes in the discharging direction by supplying a second waveform, which is included in the second drive signal among the drive signals having the waveforms determined by the control portion, to the drive element, and thereafter discharges a part or all of liquid constituting the second liquid column as a droplet.
Hereinafter, an embodiment for carrying out the present disclosure will be described with reference to the drawings. However, in each drawing, the size and scale of each part are appropriately different from the actual ones. Further, the embodiment described below is a desired specific example of the present disclosure, so various technically desirable limitations are attached, but the scope of the present disclosure is not limited to these forms unless otherwise stated to limit the present disclosure in the following description.
In the present embodiment, a liquid discharging apparatus will be described by exemplifying an ink jet printer 1 that discharges ink on a recording paper P to form an image. The ink jet printer 1 is an example of a liquid discharging apparatus. The ink is an example of “liquid”. The recording paper P is an example of a medium.
It is assumed that the ink in the present embodiment has a higher viscosity than general ink. Specifically, in the present embodiment, the viscosity of the ink is 20 millipascal seconds or more, desirably 40 millipascal seconds. Hereinafter, in the drawings, millipascal seconds may be referred to as “mPa s”.
A configuration of the ink jet printer 1 according to the present embodiment will be described with reference to
The ink jet printer 1 is supplied with print data Img indicating an image to be formed by the ink jet printer 1 and information indicating the number of print copies of the image to be formed by the ink jet printer 1 from a host computer such as a personal computer or a digital camera. The ink jet printer 1 executes a printing process of forming the image, which is indicated by the print data Img supplied from the host computer, on a recording paper P.
As illustrated in
In the present embodiment, the liquid discharging head HU includes a recording head HD provided with M discharging portions D and a switching circuit 10. In the present embodiment, “M” is an integer of 1 or more.
In the following, in order to distinguish each of the M discharging portions D provided in the recording head HD, M discharging portions D may be referred to as a first stage, a second stage, . . . , an M stage in order. Further, the m stage discharging portion D may be referred to as a discharging portion D[m]. The variable “m” is an integer satisfying 1 or more and M or less. Further, when a component, a signal, or the like of the ink jet printer 1 corresponds to a stage number m of the discharging portion D[m], a symbol for representing the component, the signal, or the like may be represented by adding a suffix[m] indicating that the component, the signal, or the like corresponds to the stages number m.
In the present embodiment, it is assumed that the ink jet printer 1 is a serial printer. Specifically, as illustrated in
The recording head HD and the discharging portion D, which is provided on the recording head HD, will be described with reference to
As illustrated in
In the present embodiment, a unimorph type as illustrated in
The piezoelectric element PZ has an upper electrode Zu, a lower electrode Zd, and a piezoelectric body Zm provided between the upper electrode Zu and the lower electrode Zd. The piezoelectric element PZ is a passive element that deforms in response to a change in potential of the drive signal Vin. When a voltage is applied between the upper electrode Zu and the lower electrode Zd by electrically coupling the lower electrode Zd to a feeder line LHb, which is set to a constant potential Vbs, and supplying the drive signal Vin to the upper electrode Zu, the piezoelectric element PZ displaces in the +Z direction or the −Z direction according to the applied voltage, and as a result of the displacement, the piezoelectric element PZ vibrates.
A vibrating plate 310 is installed on an upper surface opening portion of the cavity plate 340. The lower electrode Zd is bonded to the vibrating plate 310. Therefore, when the piezoelectric element PZ is driven by the drive signal Vin and vibrates, the vibrating plate 310 also vibrates. Thereafter, the volume of the cavity 320 changes due to the vibration of the vibrating plate 310, and the ink that fills the cavity 320 is discharged from the nozzle N. When the ink inside the cavity 320 is reduced due to the discharge of the ink, the ink is supplied from the reservoir 350.
The transport mechanism 7 transports the recording paper P in the +Y direction. Specifically, the transport mechanism 7 is provided with a transporting roller (not illustrated) whose rotation axis is parallel to the X axis direction, and a motor (not illustrated) that rotates the transporting roller under control by the control portion 6.
The movement mechanism 8 reciprocates the liquid discharging head HU along the X axis under the control of the control portion 6. As illustrated in
The storage portion 5 includes a volatile memory such as RAM and a non-volatile memory such as ROM, EEPROM, or PROM, and stores various information such as print data Img supplied from the host computer and a control program of the ink jet printer 1. The RAM is an abbreviation for Random Access Memory. The ROM is an abbreviation for Read Only Memory. The EEPROM is an abbreviation for Electrically Erasable Programmable Read-Only Memory. The PROM is an abbreviation for Programmable ROM.
The control portion 6 includes a CPU. The CPU is an abbreviation for Central Processing Unit. However, the control portion 6 may include a programmable logic device such as an FPGA instead of the CPU. The FPGA is an abbreviation for Field Programmable Gate Array.
In the control portion 6, the CPU provided in the control portion 6 operates according to a control program stored in the storage portion 5, so that the ink jet printer 1 executes the printing process.
The control portion 6 generates a print signal SI for controlling the liquid discharging head HU, a waveform designation signal dCom for controlling the drive waveform signal generation circuit 2, a signal for controlling the transport mechanism 7, and a signal for controlling the movement mechanism 8.
The waveform designation signal dCom is a digital signal that defines a waveform of the drive waveform signal Com. Further, the drive waveform signal Com is an analog signal for driving the discharging portion D. The drive waveform signal generation circuit 2 includes a DA conversion circuit and generates the drive waveform signal Com having a waveform defined by the waveform designation signal dCom.
Further, the print signal SI is a digital signal for designating the type of operation of the discharging portion D. Specifically, the print signal SI designates whether or not the ink is discharged from the discharging portion D when the discharging portion D is driven by designating whether or not to supply the drive waveform signal Com with respect to the discharging portion D.
Hereinafter, a configuration of the liquid discharging head HU will be described with reference to
As illustrated in
The switch Swa[m] switches between conduction and non-conduction between the internal wiring Lha and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the discharging portion D[m] according to the coupling state designation signal Sla[m]. For example, the switch Swa[m] turns on when the coupling state designation signal Sla[m] is at a high level and turns off when the coupling state designation signal Sla[m] is at a low level.
Hereinafter, an operation of the liquid discharging head HU will be described with reference to
In the present embodiment, an operating period of the ink jet printer 1 includes a plurality of recording periods Tu. It is assumed that the ink jet printer 1 according to the present embodiment executes the drive of each discharging portion D in the printing process in each recording period Tu. In the following description, the operating period of the ink jet printer 1 has I recording periods Tu. “I” is an integer of 2 or more. Further, the i-th recording period Tu may be referred to as a recording period Tu[i]. “i” is an integer from 1 to I.
In general, the ink jet printer 1 forms an image indicating the print data Img by repeatedly executing the printing process over a plurality of continuous or intermittent recording periods Tu to discharge the ink once or a plurality of times from each discharging portion D.
As illustrated in
As illustrated in
The drive pulse PL1 has a drive component DC1 and a drive component DC2. The drive pulse PL2 has a drive component DC3 and a drive component DC4. The drive pulse PL3 has a drive component DC5 and a drive component DC6. The drive pulse PL4 has a drive component DC7 and a drive component DC8. The drive pulse PL5 has a drive component DC9 and a drive component DC10. The drive component DC1, the drive component DC3, the drive component DC5, the drive component DC7, and the drive component DC9 cause the pressure inside the cavity 320 to decrease. The drive component DC2, the drive component DC4, the drive component DC6, the drive component DC8, and the drive component DC10 cause the pressure inside the cavity 320 to increase. In the following description, the drive components DC1 to DC10 are sometimes collectively referred to as the “drive component DC”.
As illustrated in
As illustrated in
The print signal SI includes individual designation signals Sd[1] to Sd[M] that designate the driving aspects of the discharging portions D[1] to D[M] in each recording period Tu. Thereafter, when the printing process is executed in the recording period Tu[i], as illustrated in
The individual designation signal Sd[m] according to the present embodiment is a signal that designates any one of the drive modes among the five drive modes shown below from the drive mode α1 to the drive mode α5 in each recording period Tu. In the present embodiment, as an example, it is assumed that the individual designation signal Sd[m] is a 5-bit digital signal.
Specifically, when the individual designation signal Sd[m] indicates the drive mode α1, the coupling state designation circuit 11 sets the coupling state designation signal Sla[m] to a high level in the control period Tcu1, the control period Tcu2, the control period Tcu3, the control period Tcu4, and the control period Tcu5. When the individual designation signal Sd[m] indicates the drive mode α2, the coupling state designation circuit 11 sets the coupling state designation signal Sla[m] to a low level in the control period Tcu1, the control period Tcu2, and the control period Tcu3, and sets the coupling state designation signal Sla[m] to a high level in the control period Tcu4 and the control period Tcu5. When the individual designation signal Sd[m] indicates the drive mode α3, the coupling state designation circuit 11 sets the coupling state designation signal Sla[m] to a low level in the control period Tcu1 and the control period Tcu2, and sets the coupling state designation signal Sla[m] to a high level in the control period Tcu3, the control period Tcu4, and the control period Tcu5. When the individual designation signal Sd[m] indicates the drive mode α4, the coupling state designation circuit 11 sets the coupling state designation signal Sla[m] to a low level in the control period Tcu1, and sets the coupling state designation signal Sla[m] to a high level in the control period Tcu2, the control period Tcu3, the control period Tcu4, and the control period Tcu5. When the individual designation signal Sd[m] indicates the drive mode α5, the coupling state designation circuit 11 sets the coupling state designation signal Sla[m] to a low level in the control period Tcu1, the control period Tcu2, the control period Tcu3, the control period Tcu4, and the control period Tcu5. As an example of the drive signal Vin, the drive signal Vin based on the individual designation signal Sd[m] of the drive mode α2 is illustrated with reference to
In the present embodiment, which will be described in detail later, in a stationary state of the discharging portion D to which the reference potential V0 is supplied to the piezoelectric element PZ and a state in which a position of the meniscus MS is stationary at an initial position Z0, when the drive signal Vin based on the individual designation signal Sd[m] of the drive mode α1 is supplied to the piezoelectric element PZ, the droplets DR are discharged from the nozzle N in the control period Tcu4 to the control period Tcu5.
The drive signal Vin1 is an example of a “first drive signal”. The drive signal Vin2 is an example of a “second drive signal”.
Next, due to the high viscosity of the ink, the following examples will be described with reference to
In a first embodiment, in the stationary state of the discharging portion D to which the reference potential V0 is supplied to the piezoelectric element PZ and a state in which the position of the meniscus MS is in the stationary state at the initial position Z0 illustrated in
By supplying the drive component DC10 to the piezoelectric element PZ, the position of the meniscus MS is returned to the initial position Z0 without further discharging the droplet DR continuously from the discharging portion D, the change amount of the potential per unit period in the drive component DC10 is smaller as compared with that in the drive components DC2, DC4, DC6, and DC8. Further, in the first embodiment, the change amount of the potential per unit period in the drive component DC10 may be constant while the drive component DC10 is being supplied but may change while the drive component DC10 is being supplied. The change amount of the potential per unit period in the drive components DC1, DC3, DC5, DC7, and DC9 are substantially equal. The change amount of the potential per unit period in the drive components DC2, DC4, DC6, and DC8 are substantially equal.
As illustrated in
In
The graph G2 shows a pressure fluctuation characteristic Pa2 indicating behavior of the pressure fluctuation applied to the ink inside the cavity 320 by the piezoelectric element PZ, and a pressure fluctuation characteristic Pn2 indicating behavior of the pressure fluctuation applied to the ink inside the nozzle N by the piezoelectric element PZ when the drive signal Vin having the drive pulses PL1, PL2, PL3, and PL4 is supplied to the piezoelectric element PZ. That is, the graph G2 shows the pressure fluctuation characteristic Pa2 of the ink inside the cavity 320 and the pressure fluctuation characteristic Pn2 of the ink inside the nozzle N when the drive signal Vin having both the waveform PH1 and the waveform PH2 is supplied to the piezoelectric element PZ. The point Pn2p in the pressure fluctuation characteristic Pn2 indicates the highest pressure of the pressure that can be applied to the ink inside the nozzle N and a time point when this pressure is generated while the drive pulse PL4 is being supplied to the piezoelectric element PZ in the period that the drive signal Vin having the drive pulses PL1, PL2, PL3, and PL4 is being supplied to the piezoelectric element PZ. The pressure indicated by the point Pn2p is substantially 1.2×1006 Pascal. Further, the pressure indicated by the point Pn2p corresponds to an increment amount that is a fluctuation amount of the pressure of the ink inside the nozzle N when the drive pulse PL4 is supplied to the piezoelectric element PZ while the drive signal Vin having the drive pulses PL1, PL2, PL3, and PL4 is being supplied to the piezoelectric element PZ, and that is the fluctuation amount from the pressure of the ink inside the nozzle N where the discharging portion D is in the stationary state to the positive pressure side.
The point Pn2m in the pressure fluctuation characteristic Pn2 indicates the lowest pressure of the pressure that can be applied to the ink inside the nozzle N and a time point when this pressure is generated while the drive pulse PL4 is being supplied to the piezoelectric element PZ in the period that the drive signal Vin having the drive pulses PL1, PL2, PL3, and PL4 is being supplied to the piezoelectric element PZ. The pressure indicated by the point Pn2m is substantially −1.2×1006 Pascal. Further, the pressure indicated by the point Pn2m corresponds to a decrement amount that is a fluctuation amount of the pressure of the ink inside the nozzle N when the drive pulse PL4 is supplied to the piezoelectric element PZ while the drive signal Vin having the drive pulses PL1, PL2, PL3, and PL4 is being supplied to the piezoelectric element PZ, that is the fluctuation amount from the pressure of the ink inside the nozzle N where the discharging portion D is in the stationary state to the negative pressure side.
The time point indicated by the point Pn1m and the time point indicated by the point Pn2m coincide with the time point at which the supply of the drive component DC7 is ended. Further, the time point indicated by the point Pn1p and the time point indicated by the point Pn2p coincide with the time point at which the supply of the drive component DC8 is ended.
As shown in the graph G1 in
Normally, when the ink with a viscosity of less than 20 millipascal seconds is used, by setting intervals between a plurality of drive pulses as resonance timing, the pressure fluctuation caused by the rear side drive pulse resonates with the pressure fluctuation caused by the preceding drive pulse and becomes larger, and along with this, the fluctuation amount of the pressure of the liquid inside the nozzle at the time of supplying the rear side drive pulse to the piezoelectric element is larger than the fluctuation amount of the pressure of the liquid inside the nozzle at the time of supplying the preceding drive pulse to the piezoelectric element. However, in the present embodiment, the fluctuation amount of the pressure of the liquid inside the nozzle at the time of supplying only the drive pulse PL4 shown in the graph G1 is substantially equal as described above to the fluctuation amount of the pressure of the liquid inside the nozzle at the time of continuously supplying the drive pulses PL1, PL2, PL3, and PL4 shown in the graph G2 to the piezoelectric element PZ. This is considered to indicate that the pressure fluctuation caused by the preceding drive pulse PL and the pressure fluctuation caused by the subsequent drive pulse PL do not resonate because the ink according to the present embodiment has a high viscosity.
Next, the volume velocity of the ink inside the nozzle N caused by the drive signal Vin will be described with reference to
The graph G4 shows a fluctuation characteristic Vn4 indicating the behavior of the volume velocity of the ink inside the nozzle N when the drive signal Vin having the drive pulses PL1, PL2, PL3, and PL4 is supplied to the piezoelectric element PZ. A point Vn4p in the fluctuation characteristic Vn4 indicates the volume velocity of the ink inside the nozzle N, which is the largest in the +Z direction, and a time point when this volume velocity is generated when the drive pulse PL4 is supplied to the piezoelectric element PZ. The volume velocity indicated by the point Vn4p is substantially 2.7×10−06 cubic meters per second. A point Vn4m in the fluctuation characteristic Vn4 indicates the volume velocity, which is the largest in the −Z direction, and a time point when this volume velocity is generated when the drive pulse PL4 is supplied to the piezoelectric element PZ. The volume velocity indicated by the point Vn4m is substantially −3.3×10−6 cubic meters per second.
The time point indicated by the point Vn3p and the time point indicated by the point Vn4p coincide with the time point at which the supply of the drive component DC7 is ended. Further, the time point indicated by the point Vn3m and the time point indicated by the point Vn4m coincide with the time point at which the supply of the drive component DC8 is ended.
As illustrated in
Similar to the pressure fluctuation characteristic caused by the drive signal Vin described above with reference to
Referring back to
The natural vibration cycle TC is the reciprocal of a natural frequency of the discharging portion D and can be generally represented by using the following equation (1).
In the above equation (1), M indicates inertia of a flow path, and C indicates a sum of a compliance Cν of the vibrating plate 310 and a compressibility CL of the ink. ζ is a value less than 1 and can be represented by using the following equation (2).
In the above equation (2), R indicates a viscosity resistance of the flow path and is proportional to the viscosity of the ink.
Hereinafter, a value obtained by dividing the period Pw by the natural vibration cycle TC of the discharging portion D is referred to as a “pulse interval ratio”. The vertical axis of the graph G5 shows the above-mentioned discharge performance value. Each of a plurality of black circles in the graph G5 indicates the pulse interval ratio and the discharge performance value obtained by experiments. Further, in the graph G5, a characteristic CPw of the pulse interval ratio calculated based on the pulse interval ratio and the discharge performance value obtained by the experiments is shown. The characteristic CPw is calculated based on, for example, the method of least squares.
As shown in the graph G5, in a mode in which the pulse interval ratio is 1 or more and 2 or less, the discharge performance value is substantially 1.8×10−10 Newton seconds or more, and as compared with a mode in which the pulse interval ratio is less than 1 and a mode in which the pulse interval ratio is larger than 2, the discharge performance value can be increased. For example, when the period Pw68 is less than the pulse interval ratio 1, the drive component DC8 is started while the volume of the cavity 320 is still being expanded. That is, when the period Pw68 is less than the pulse interval ratio 1, the discharge performance value is lowered because the drive component DC8 is started in a state in which the volume of the cavity 320 is smaller than the volume of the cavity 320 at the time point tDC8 where the drive component DC8 is started when the pulse interval ratio is 1 or more and 2 or less for the period Pw68. In a mode in which the pulse interval ratio is 1.2 or more and 1.6 or less, the discharge performance value is substantially 2.3×10−10 Newton seconds or more, and as compared with a mode in which the pulse interval ratio is less than 1.2 and a mode in which the pulse interval ratio is larger than 1.6, the discharge performance value can be increased. Note that, substantially 1.8×10−1 Newton seconds correspond to 20 ng×9 m/s, and substantially 2.3×10−10 Newton seconds correspond to 23 ng×10 m/s. “1 ng” indicates 10−9 grams.
As illustrated in
The process of the control portion 6 will be described more specifically. When discharging the droplet DR is from the nozzle N in the recording period Tu[j], the control portion 6 generates the individual designation signal Sd[m] of the recording period Tu[j] based on the individual designation signal Sd[m] of the recording period Tu[j−1], the individual designation signal Sd[m] of the recording period Tu[j−2], and the individual designation signal Sd[m] of the recording period Tu[j−3], which are the individual designation signals Sdx of the predetermined recording period Tux preceding the recording period Tu[j]. More specifically, when discharging the droplet DR from the nozzle N in the recording period Tu[j], the control portion 6 determines whether or not the drive signal Vin1 of the drive signal Vin, which is supplied in the recording period Tu[j], selects each of the drive pulse PL1, the drive pulse PL2, and the drive pulse PL3 based on the individual designation signal Sd[m] of the recording period Tu[j−1], the individual designation signal Sd[m] of the recording period Tu[j−2], and the individual designation signal Sd[m] of the recording period Tu[j−3], which are the individual designation signals Sdx of the predetermined recording period Tux preceding the recording period Tu[j]. On the other hand, when discharging the droplet DR in the recording period Tu[j], the control portion 6 determines that the drive signal Vin2 of the drive signal Vin, which is supplied in the recording period Tu[j], has the waveform PH2 including the drive pulse PL4 and the drive pulse PL5 regardless of the individual designation signal Sd[m] of the recording period Tu[j−1], the individual designation signal Sd[m] of the recording period Tu[j−2], and the individual designation signal Sd[m] of the recording period Tu[j−3], which are the individual designation signals Sdx of the predetermined recording period Tux preceding the recording period Tu[j]. A more specific recording method will be described with reference to
In step S2, the control portion 6 substitutes 1 for the variable m. Next, in step S4, the control portion 6 determines whether or not to cause the discharging portion D[m] to discharge the droplet in the recording period Tu[j] based on the print data Img. When the determination result in step S4 is positive, in step S6, the control portion 6 acquires the individual designation signal Sd[m] of the recording period Tu[i], that is the recording period Tu[j−1] from the storage portion 5. Next, in step S8, the control portion 6 determines whether or not the discharging portion D[m] discharges the droplet DR in the recording period Tu[j−1] based on the individual designation signal Sd[m] of the recording period Tu[j−1]. For example, when the individual designation signal Sd[m] of the recording period Tu[j−1] designates any of the drive modes α1, α2, α3, and α4, the control portion 6 determines that the droplet DR is discharged from the discharging portion D[m] in the recording period Tu[j−1]. On the other hand, when the individual designation signal Sd[m] of the recording period Tu[j−1] designates the drive mode α5, the control portion 6 determines that the droplet DR is not discharged from the discharging portion D[m] in the recording period Tu[j−1].
When the determination result in step S8 is negative, in step S10, the control portion 6 acquires the individual designation signal Sd[m] of the recording period Tu[j−2] from the storage portion 5. Next, in step S12, the control portion 6 determines whether or not the discharging portion D[m] discharges the droplet DR in the recording period Tu[j−2] based on the individual designation signal Sd[m] of the recording period Tu[j−2].
When the determination result in step S12 is negative, in step S14, the control portion 6 acquires the individual designation signal Sd[m] of the recording period Tu[j−3] from the storage portion 5. Next, in step S16, the control portion 6 determines whether or not the discharging portion D[m] discharges the droplet DR in the recording period Tu[j−3] based on the individual designation signal Sd[m] of the recording period Tu[j−3].
When the determination result in step S16 is negative, that is, when the droplet DR is not discharged from the discharging portion D[m] in the three preceding recording periods Tu of the recording period Tu[j−1], the recording period Tu[j−2], and the recording period Tu[j−3], in step S18, the control portion 6 generates the individual designation signal Sd[m] of the drive mode α1. In the process in step S18, it can be said that the control portion 6 determines that the drive signal Vin1 has the waveform PH1 including the three drive pulses PL of the drive pulse PL1, the drive pulse PL2, and the drive pulse PL3. After the process in step S18 is ended, in step S32, the control portion 6 stores the generated individual designation signal Sd[m] in the storage portion 5.
When the determination result in step S4 is negative, that is, when the droplet DR is not discharged from the discharging portion D[m] in the recording period Tu[j], in step S20, the control portion 6 generates the individual designation signal Sd[m] of the drive mode α5. Thereafter, in step S32, the control portion 6 stores the generated individual designation signal Sd[m] in the storage portion 5.
When the determination result in step S8 is positive, that is, when the droplet DR is discharged from the discharging portion D[m] in the recording period Tu[j−1], in step S22, the control portion 6 generates the individual designation signal Sd[m] of the drive mode α2. In the process in step S22, it can be said that the control portion 6 determines that the drive signal Vin1 has zero drive pulse PL, that is, has no waveform PH1. Further, in the process in step S8, the control portion 6 determines whether or not the waveform PH1 is included in the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux.
After the process in step S22 is ended, in step S32, the control portion 6 stores the generated individual designation signal Sd[m] in the storage portion 5.
When the determination result in step S12 is positive, that is, when the droplet DR is not discharged from the discharging portion D[m] in the recording period Tu[j−1] but the droplet DR is discharged from the discharging portion D[m] in the recording period Tu[j−2], in step S24, the control portion 6 generates the individual designation signal Sd[m] of the drive mode α3. In the process in step S24, it can be said that the control portion 6 determines that the drive signal Vin1 has the waveform PH1 including one drive pulse PL of the drive pulse PL3. After the process in step S22 is ended, in step S32, the control portion 6 stores the generated individual designation signal Sd[m] in the storage portion 5.
When the determination result in step S16 is positive, that is, when the droplet DR is not discharged from the discharging portion D[m] in the recording period Tu[j−1] and the recording period Tu[j−2] but the droplet DR is discharged from the discharging portion D[m] in the recording period Tu[j−3], in step S26, the control portion 6 generates the individual designation signal Sd[m] of the drive mode α4. In the process in step S26, it can be said that the control portion 6 determines that the drive signal Vin1 has the waveform PH1 including the two drive pulses PL of the drive pulse PL2 and the drive pulse PL3. After the process in step S26 is ended, in step S32, the control portion 6 stores the generated individual designation signal Sd[m] in the storage portion 5.
In the processes of steps S12 and S16, the control portion 6 further determines the number of drive pulses PL included in the waveform PH1 based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux when it is determined that the waveform PH1 is included in the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j].
Further, in the processes of steps S8, S12, and S16, the control portion 6 determines the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] such that the number of drive pulses PL included in the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j] when the droplet DR is not discharged from the discharging portion D in the recording period Tu[j−1] is larger than the number of drive pulses PL included in the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j] when the droplet DR is discharged from the discharging portion D in the recording period Tu[j−1].
After the process in step S32 is ended, in step S34, the control portion 6 determines whether or not the variable m reaches M, which is the number of discharging portions D. When the determination result in step S34 is negative, in step S38, the control portion 6 increases the value of the variable m by one and returns the process to step S4. When the determination result in step S34 is positive, in step S36, the control portion 6 outputs the individual designation signals Sd[1] to Sd[M] to the switching circuit 10. After the process in step S36 is ended, the control portion 6 ends a series of processes illustrated in
The case where the value of the variable j is 2 will be described. When the determination result in step S8 is negative, the control portion 6 executes the process in step S18 instead of the process in step S10. Next, the case where the value of the variable j is 3 will be described. When the determination result in step S12 is negative, the control portion 6 executes the process in step S18 instead of the process in step S14. Since the process after the process in step S18 is ended is the same as the series of processes illustrated in
The discharge mode illustrated in a first stage in
Regarding the recording period Tu[2], the control portion 6 executes the processes in the flowcharts illustrated in
The discharge mode illustrated in a second stage in
Regarding the recording period Tu[3], the control portion 6 executes the processes in the flowcharts illustrated in
The discharge mode illustrated in a third stage in
The discharge mode illustrated in a fourth stage in
Regarding the recording period Tu[5], since the determination result in step S16 is negative, the control portion 6 generates the individual designation signal Sd[m] of the drive mode α1 by executing the process in step S18 and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, the discharging portion D[m] is supplied with the drive signal Vin having the drive pulses PL1, PL2, PL3, PL4, and PL5 in the recording period Tu[5].
The round-up of the first embodiment is described below.
As described above, the liquid discharging head HU according to the first embodiment has M discharging portions D. The discharging portion D includes the piezoelectric element PZ that displaces by being supplied with the drive signal Vin, the cavity 320 inside which pressure is increased or decreased according to the displacement of the piezoelectric element PZ, and the nozzle N that communicates with the cavity 320 and is capable of discharging the ink that fills inside the cavity 320 according to the increase or decrease in the pressure inside the cavity 320 as droplets in the −Z direction. The liquid discharging head HU executes a drive method including the following first step and a second step. In the first step, the meniscus MS forms the liquid column LC6 protruding in the −Z direction by supplying the piezoelectric element PZ with the drive signal Vin1 having the waveform PH1 including the drive pulses PL1, PL2, and PL3 having drive components DC1, DC3, and DC5 that cause the pressure inside the cavity 320 to decrease and the drive components DC2, DC4, and DC6 that cause the pressure inside the cavity 320 to increase. In the second step, when the liquid column LC6 is formed, a part or all of the ink constituting the liquid column LC8 is discharged as the droplet DR after the meniscus MS forms the liquid column LC8 protruding in the −Z direction by supplying the piezoelectric element PZ with the drive signal Vin2 having the waveform PH2 including the drive pulses PL4 and PL5 having drive components DC7 and DC9 that cause the pressure inside the cavity 320 to decrease and the drive components DC8 and DC10 that cause the pressure inside the cavity 320 to increase. When the drive signal Vin having the waveform PH1 bur not having the waveform PH2 is supplied to the piezoelectric element PZ, the droplet DR is not discharged from the discharging portion D, and when the drive signal Vin having the waveform PH2 but not having the waveform PH1 is supplied to the piezoelectric element PZ, the droplet DR is not discharged from the discharging portion D.
The drive signal Vin having the waveform PH1 is specifically a drive signal Vin based on the individual designation signal Sd[m] that designates the drive mode α1, the drive mode α3, and the drive mode α4.
In the section “Round-up of Waveform PH1 and Waveform PH2”, the waveform PH1 is an example of a “first waveform”. The waveform PH2 is an example of a “second waveform”. The liquid column LC6 is an example of a “first liquid column”. The liquid column LC8 is an example of a “second liquid column”. Further, the drive pulses PL1, PL2, and PL3 are examples of “first drive pulses”, and the drive pulses PL4 and PL5 are examples of “second drive pulses”. Further, the drive components DC1, DC3, and DC5 are examples of “first drive components that cause the pressure inside the pressure chamber to decrease”, the drive components DC2, DC4, and DC6 are examples of “second drive components that cause the pressure inside the pressure chamber to increase”, the drive components DC7 and DC9L are examples of “third drive components that cause the pressure inside the pressure chamber to decrease”, and the drive components DC8 and DC10 are examples of “fourth drive components that cause the pressure inside the pressure chamber to increase”.
When the viscosity of the ink becomes 20 millipascal seconds or more, there is a possibility that the droplet DR cannot be discharged with one drive pulse PL1 in a standby state in which the ink inside the discharging portion D is held under constant negative pressure. In order to discharge the ink having a high viscosity, it is conceivable to increase the difference between the highest potential and the lowest potential of the drive signal Vin, but there is a physical limit. Further, it is conceivable to increase the excluded volume of the cavity 320, but when the capacitance of the cavity 320 is increased, a structure of the discharging portion D is easily deformed by the force applied to the structure, that is, a compliance of the flow path in the discharging portion D is increased. The excluded volume means the fluctuation amount of the volume of the pressure chamber caused by the vibration of the vibrating plate 310. When the compliance of the flow path in the discharging portion D is increased, the pressure fluctuation generated by the displacement of the piezoelectric element PZ is easily alleviated by the deformation of the structure of the discharging portion D, so that it becomes difficult to discharge the droplet DR. Further, when the capacitance of the cavity 320 is increased, the pressure generated by the displacement of the piezoelectric element PZ is easily absorbed by the compression of the ink so that it becomes difficult to discharge the droplet DR.
Therefore, according to the first embodiment, when the liquid column LC6 is formed by the drive signal Vin1 having the waveform PH1, by supplying the drive signal Vin2 having the waveform PH2 to the piezoelectric element PZ, the liquid column formed in the Meniscus MS can be grown, and a part or all of the ink constituting the liquid column LC8 can be discharged as the droplet DR.
Further, a first decrement amount, which is the fluctuation amount of the pressure of the ink inside the nozzle N toward the negative pressure side at the time of supplying the drive component DC7 of the waveform PH2 included in the drive signal Vin to the piezoelectric element PZ when the drive signal Vin having the waveform PH2 but not having the waveform PH1 is supplied to the piezoelectric element PZ, is substantially equal to a second decrement amount, which is the fluctuation amount of the pressure of the ink inside the nozzle N toward the negative pressure side at the time of supplying the drive component DC7 of the waveform PH2 included in the drive signal Vin to the piezoelectric element PZ when the drive signal Vin having the waveform PH1 and the waveform PH2 is supplied to the piezoelectric element PZ. Further, a first increment amount, which is the fluctuation amount of the pressure of the ink inside the nozzle toward the positive pressure side at the time of supplying the drive component DC8 of the waveform PH2 included in the drive signal Vin to the piezoelectric element PZ when the drive signal Vin having the waveform PH2 but not having the waveform PH1 is supplied to the piezoelectric element PZ, is substantially equal to a second increment amount, which is the fluctuation amount of the pressure of the ink inside the nozzle N toward the positive pressure side at the time of supplying the drive component DC8 of the waveform PH2 included in the drive signal Vin to the piezoelectric element PZ when the drive signal Vin having the waveform PH1 and the waveform PH2 is supplied to the piezoelectric element PZ.
The higher the viscosity of the ink, the faster the attenuation of residual vibration. Therefore, after the waveform PH1 is supplied to the piezoelectric element PZ, the attenuation of the residual vibration occurs due to the waveform PH1 at the time point when the waveform PH2 is supplied to the piezoelectric element PZ, and resonance cannot be generated due to the synchronization of the waveform PH2 with the residual vibration caused by the waveform PH1. In the first embodiment, the first decrement amount and the second decrement amount described above are substantially equal, and further, the first increment amount and the second increment amount are substantially equal, so that the residual vibration caused by the waveform PH1 and the pressure vibration generated by the waveform PH2 do not resonate. However, in the first embodiment, since the droplet DR is discharged by forming the liquid column to be formed in the meniscus MS by a plurality of times of the drive pulses PL, the waveform PH1 and the waveform PH2 are not adjusted such that the waveform PH2 is generated to resonate with the residual vibration caused by the waveform PH1 but are adjusted so as to form the meniscus MS by the plurality of times of the drive pulses PL. Therefore, according to the first embodiment, even when the ink has a high viscosity, the droplet DR can be discharged by forming the liquid column to be formed in the meniscus MS by the waveform PH1 and the waveform PH2.
The pull-in position Zp4, which is a position of the most pulled-in part of the meniscus MS inside the discharging portion D in the +Z direction, at the time of supplying the drive component DC7 of the waveform PH2 to the piezoelectric element PZ when the drive signal Vin2 having the waveform PH2 is supplied to the piezoelectric element PZ following the drive signal Vin1 having the waveform PH1, is positioned in the +Z direction with respect to the pull-in position Zp1 that corresponds to the most pulled-in part of the meniscus MS in the +Z direction, at the time of supplying the drive component DC7 of the waveform PH2 to the piezoelectric element PZ when the drive signal Vin having the waveform PH2 is supplied to the piezoelectric element PZ without supplying the drive signal VmI having the waveform PH1 to the piezoelectric element PZ.
As described above, in the first embodiment, by supplying the plurality of drive pulses PL to the piezoelectric element PZ, the most pulled-in part of the meniscus MS in the +Z direction moves in the −Z direction so that the liquid column formed in the meniscus MS also moves in the −Z direction. As the liquid column moves in the −Z direction, the front end of the liquid column in the −Z direction moves away from the initial position Z0 in the −Z direction so that a part or all of the liquid column can be easily separated, and the droplet DR separated from the liquid column can be discharged.
Further, in the second step, when the front end of the liquid column LC8 moves in the −Z direction, the drive component DC9 included in the drive pulse PL5 of the drive signal Vin is supplied to the piezoelectric element PZ.
When the front end of the liquid column LC8 moves in the −Z direction, the droplet DR is torn off from the liquid column LC9 by supplying the drive signal Vin having the drive component DC9 to the piezoelectric element PZ. According to the present embodiment, a more stable discharge can be realized as compared with an aspect in which the drive signal Vin not having the drive component DC9 is supplied to the piezoelectric element PZ.
The waveform PH1 includes the drive pulses PL1, PL2, and PL3. The drive pulse PL1 includes the drive component DC1 and the drive component DC2. The drive pulse PL2 includes the drive component DC3 and the drive component DC4. The drive pulse PL3 includes the drive component DC5 and the drive component DC6.
As described with reference to
In the present embodiment, since the waveform PH1 has three drive pulses PL, even when the droplet DR cannot be discharged with one drive pulse PL, the liquid column to be formed in the Meniscus MS can be grown by supplying the drive signal Vin having the waveform PH1 including two or three drive pulses PL to the piezoelectric element PZ, and thus a part or all of the ink constituting the liquid column LC8 can be discharged by the waveform PH2 as the droplet DR.
As described with reference to
Further, the viscosity of the ink in the liquid discharging head HU is 20 millipascal seconds or more, desirably 40 millipascal seconds. When the viscosity of the ink becomes 20 millipascal seconds or more, it may not be possible to discharge the droplet DR with only one drive pulse PL4 of the waveform PH2, but by the drive method according to the present embodiment in which the waveform PH1 is provided before the waveform PH2, the droplet DR can be discharged even for the ink that has a viscosity of 20 millipascal seconds or more.
The difference between the highest potential and the lowest potential in the waveform PH1 is substantially equal to the difference between the highest potential and the lowest potential in the waveform PH2. More specifically, the lowest potential in the waveform PH1 and the lowest potential in the waveform PH2 are the potentials VL1 and are substantially equal to each other, and the highest potential in the waveform PH1 and the highest potential in the waveform PH2 are the reference potentials V0 and are substantially equal to each other. The highest potential that can be realized in the ink jet printer 1 is defined as the highest potential of the waveform PH1 and the waveform PH2, and by setting the lowest potential that can be realized in the ink jet printer 1 to the lowest potential of the waveform PH1 and the waveform PH2, even when the ink has a high viscosity, the liquid column can grow in the meniscus MS by the waveform PH1, and the droplet DR can be discharged by the waveform PH2.
As described above, the liquid discharging head HU in the first embodiment executes the drive method including the first step and the second step described above. The waveform PH1 has three drive pulses PL having the drive components DC1, DC3, and DC5 that cause the pressure inside the cavity 320 to decrease and the drive components DC2, DC4, and DC6 that cause the pressure inside the cavity 320 to increase. The waveform PH2 has two drive pulses PL having the drive components DC7 and DC9 that cause the pressure inside the cavity 320 to decrease and the drive components DC8 and DC10 that cause the pressure inside the cavity 320 to increase. The waveform PH2 is started at the end time point of the waveform PH1. The period Pw68, which is an interval between the rearmost drive pulse PL3 of the drive pulse PL of the waveform PH1 and the foremost drive pulse PL4 of the drive pulse PL of the waveform PH2, is 1 time or more and 2 times or less the natural vibration cycle TC of the discharging portion D. The period Pw68 is a period from the time point tDC6 when the supply of the drive component DC6 included in the rearmost drive pulse PL3 of the three drive pulses PL included in the waveform PH1 is started to the time point tDC8 when the supply of the drive component DC8 included in the foremost drive pulse PL4 of the two drive pulses PL included in the waveform PH2 is started.
By the fact that the period Pw68 is 1 time or more and 2 times or less the natural vibration cycle TC, the discharge performance value can be increased as compared with an aspect in which the period Pw68 is less than 1 time the natural vibration cycle TC and an aspect in which the period Pw68 is larger than 2 times the natural vibration cycle TC.
The drive pulses PL1, PL2, and PL3 included in the waveform PH1 are examples of the “first drive pulses”. The drive components DC1, DC3, and DC5 are examples of the “first drive components”. The drive components DC2, DC4, and DC6 are examples of the “second drive components”. The drive pulses PL4 and PL5 included in the waveform PH2 are examples of the “second drive pulses”. The drive components DC7 and DC9 are examples of the “third drive components”. The drive components DC8 and DC10 are examples of the “fourth drive components”. The period Pw68 corresponds to a “first period”.
Further, the period Pw68 is 1.2 times or more and 1.6 times or less the natural vibration cycle TC. By the fact that the period Pw68 is 1.2 times or more and 1.6 times or less of the natural vibration cycle TC, the discharge performance value can be increased as compared with an aspect in which the period Pw68 is less than 1.2 times the natural vibration cycle TC and an aspect in which the period Pw68 is larger than 1.6 times the natural vibration cycle TC.
Further, the periods Pw24 and Pw46, which are intervals of pulses of the drive pulses PL1 to PL3 included in the waveform PH1, are 1 time or more and 2 times or less the natural vibration cycle TC. The period Pw24 is a period from the time point tDC2 when the supply of the drive component DC2 included in the drive pulse PL1 of the three drive pulses PL included in the waveform PH1 is started to the time point tDC4 when the supply of the drive component DC4 included in the next drive pulse PL2 of the drive pulse PL1 is started. The period Pw46 is a period from the time point tDC4 when the supply of the drive component DC4 included in the drive pulse PL2 of the three drive pulses PL included in the waveform PH1 is started to the time point tDC6 when the supply of the drive component DC6 included in the next drive pulse PL3 of the drive pulse PL2 is started.
By the fact that the periods Pw24 and Pw46 are 1 time or more and 2 times or less the natural vibration cycle TC, the discharge performance value can be increased as compared with an aspect in which the periods Pw24 and Pw46 are less than 1 time the natural vibration cycle TC and an aspect in which the periods Pw24 and Pw46 are larger than 2 times the natural vibration cycle TC.
The periods Pw24 and Pw46 are examples of “second periods”. When the period Pw24 is an example of the “second period”, the drive pulse PL1 corresponds to the “one of the first drive pulses”, and the drive pulse PL2 corresponds to the “one of the next first drive pulses of the first drive pulse”. When the period Pw46 is an example of the “second period”, the drive pulse PL2 corresponds to the “one of the first drive pulses”, and the drive pulse PL3 corresponds to the “one of the next first drive pulses of the first drive pulse”.
Further, the periods Pw24 and Pw46 are 1.2 times or more and 1.6 times or less the natural vibration cycle TC. By the fact that the periods Pw24 and Pw46 are 1.2 times or more and 1.6 times or less the natural vibration cycle TC, the discharge performance value can be increased as compared with an aspect in which the periods Pw24 and Pw46 are less than 1.2 times the natural vibration cycle TC and an aspect in which the periods Pw24 and Pw46 are larger than 1.6 times the natural vibration cycle TC.
As described above, the liquid discharging head HU according to the first embodiment has M discharging portions D. The discharging portion D includes the piezoelectric element PZ, the cavity 320, and the nozzle N. The piezoelectric element PZ displaces according to the drive signal Vin including the drive signal Vin1 and the drive signal Vin2 supplied in each of the plurality of recording periods Tu including the recording period Tu[j]. The control portion 6 executes the recording method having the first step. In the first step, when discharging the droplet DR from the nozzle N in the recording period Tu[j], a waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] is determined based on a waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording periods Tu[j−1] to Tu[j−3], which are the recording periods Tu preceding the recording period Tu[j]. When the drive signal Vin having the waveform determined in the first step has the waveform PH1 in the drive signal Vin1 and has the waveform PH2 in the drive signal Vin2, by supplying the drive signal Vin1 to the piezoelectric element PZ in the recording period Tu[j], the meniscus MS forms the liquid column LC6 protruding in the −Z direction, and when the liquid column LC6 is formed, by supplying the drive signal Vin2 to the piezoelectric element PZ, the meniscus MS forms the liquid column LC8 protruding in the −Z direction, and thereafter a part or all of the ink constituting the liquid column LC8 is discharged as the droplet.
For example, in a case where the drive signal Vin based on the individual designation signal Sd[m] that designates the drive mode α1 is supplied to the piezoelectric element PZ in the stationary state of the discharging portion D, after discharging the droplet DR within the recording period Tu[j−1] preceding the recording period Tu[j] for the ink having a viscosity to the extent that the droplet DR is discharged at the timing when the waveform PH2 is supplied, when the drive signal Vin based on the individual designation signal Sd[m] that designates the drive mode α1 is supplied to the piezoelectric element PZ in the recording period Tu[j], there is a possibility that the droplet DR is discharged when the waveform PH1 is being supplied, for example, which is not the timing at which the droplet DR should be originally discharged, and the printing quality deteriorates.
A state of the meniscus MS at the start time point of the recording period Tu[j] can be estimated by using the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux preceding the recording period Tu[j]. Therefore, by determining the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux preceding the recording period Tu[j], the droplet DR can be discharged so as to approach the timing at which the droplet DR should be originally discharged, and thus the deterioration of the printing quality can be reduced.
The recording period Tu[j] is an example of a “first recording period”, and the predetermined recording periods Tux, which precede the recording period Tu[j] and are used for determining the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j], that is the recording periods Tu[j−1] to Tu[j−3] in the present embodiment, are examples of “predetermined recording periods preceding the first recording period”.
The predetermined recording period Tux, which precedes the recording period Tu[j] and is used for determining the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j], includes the recording period Tu[j−1] that is ended at the start of the recording period Tu[j]. Of the two or more recording periods Tu that are ended before the start of the recording period Tu[j], the most influential factor on the meniscus MS at the start time point of the recording period Tu[j] is the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j−1]. Therefore, by determining the individual designation signal Sd[m] of the recording period Tu[j] based on the individual designation signal Sd[m] of the predetermined recording period Tux preceding the recording period Tu[j] including the recording period Tu[j−1], the deterioration of the printing quality can be reduced as compared with an aspect of determining the individual designation signal Sd[m] of the recording period Tu[j] based on the individual designation signal Sd[m] of the predetermined recording period Tu preceding the recording period Tu[j] that does not include the recording period Tu[j−1].
The recording period Tu[j−1] is an example of a “second recording period”.
In the first step in the section “Round-up of Recording Method Using Drive Waveform Signal Com”, the predetermined recording period Tux, which precedes the recording period Tu[j] and is used for determining the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j], includes the recording period Tu[j−1] and includes the continuous recording periods Tu[j−1] to Tu[j−3] that are ended before the start of the recording period Tu[j].
The most influential factor on the meniscus MS at the start time point of the recording period Tu[j] is the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j−1], but the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu before the recording period Tu[j−1] is also an influential factor on the meniscus MS at the start time point of the recording period Tu[j]. Therefore, according to the present embodiment, as compared with an aspect of determining the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] based only on the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j−1], the state of the meniscus MS at the start time point of the recording period Tu[j] can be estimated more precisely, and thus the deterioration of the printing quality can be further reduced.
The recording periods Tu[j−1] to Tu[j−3] are examples of “two or more consecutive recording periods including the second recording period and ended before the start of the first recording period”.
In the first step in the section “Round-up of Recording Method Using Drive Waveform Signal Com”, the waveform of the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j] is determined based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux preceding the recording period Tu[j].
By adjusting the waveform of the drive signal Vin1, the droplet DR can be discharged so as to approach the timing at which the droplet DR should be originally discharged so that deterioration of the printing quality can be further reduced.
Further, in the first step in the section “Round-up of Recording Method Using Drive Waveform Signal Com”, in the predetermined recording period Tux preceding the recording period Tu[j], which is used for determining the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j], it is determined whether or not the waveform PH1 is included in the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j] based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ.
Further, in the first step in the section “Round-up of Recording Method Using Drive Waveform Signal Com”, in the predetermined recording period Tux preceding the recording period Tu[j], which is used for determining the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j], when it is determined that the waveform PH1 is included in the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j] based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ, the number of drive pulses PL included in the waveform PH1 is further determined.
As in the present embodiment, an aspect, in which the number of drive pulses PL included in the drive signal Vin1 is adjusted, can be realized by a simple configuration as compared with an aspect in which the lowest potential and the highest potential of the drive pulse PL included in the drive signal Vin1 are adjusted. The aspect, in which the lowest potential and the highest potential of the drive pulse PL are adjusted, can be realized by, for example, the following configuration. The drive waveform signal generation circuit 2 generates a first drive waveform signal Com-A and a second drive waveform signal Com-B. The difference between the lowest potential and the highest potential of the drive pulse PL corresponding to the drive signal Vin1 of the first drive waveform signal Com-A is larger than the difference between the lowest potential and the highest potential of the drive pulse PL corresponding to the drive signal Vin1 of the second drive waveform signal Com-B. The switching circuit 10 supplies one of the first drive waveform signal Com-A and the second drive waveform signal Com-B to the piezoelectric element PZ. However, in the above configuration, when the types of the drive waveform signal Com are increased, the drive waveform generation circuit becomes large, and the configuration becomes more complicated as compared with the present embodiment. Further, although there is a limit to the lowest potential and the highest potential capable of being supplied to the piezoelectric element PZ in the ink jet printer 1, as described above, by supplying a plurality of drive pulses PL to the piezoelectric element PZ, the pressure inside the cavity 320 is repeatedly decreased and increased, thereby even when the ink has a high viscosity, the liquid column can be grown and discharged as the droplet DR.
Therefore, according to the present embodiment, with a simpler configuration, it is possible to generate the waveform of the drive signal Vin1 that matches the state of the meniscus MS at the start time point of the recording period Tu[j] as compared with the aspect in which the lowest potential and the highest potential of the drive pulse PL included in the drive signal Vin1 are adjusted.
The predetermined recording period Tux, which precedes the recording period Tu[j] and is used for determining the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j], includes the recording period Tu[j−1]. Further, in the first step in the section “Round-up of Recording Method Using Drive Waveform Signal Com”, the waveform of the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j] is determined such that a first of the number of drive pulses PL included in the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j] when the droplet DR is not discharged from the discharging portion D in the recording period Tu[j−1] is larger than a second of the number of drive pulses PL included in the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j] when the droplet DR is discharged from the discharging portion D in the recording period Tu[j−1].
A liquid column formed in the meniscus MS at the start time point of the recording period Tu[j] in a first situation where the recording period Tu[j−1] is the non-discharge recording period Tu-N is smaller than a liquid column formed in the meniscus MS at the start time point of the recording period Tu[j] in a second situation where the recording period Tu[j−1] is the discharge recording period Tu-D. Therefore, in order to discharge the droplet DR at the timing at which the droplet DR should be originally discharged in the first situation, it is necessary to supply the drive signal Vin1 having a larger number of drive pulses PL to the piezoelectric element PZ as compared with the second situation. Therefore, the droplet DR can be discharged at the timing at which the droplet DR should be originally discharged by determining the waveform of the drive signal Vin1 supplied to the piezoelectric element PZ in the recording period Tu[j] such that the first of the number of drive pulses PL is larger than the second of the number of drive pulses PL.
When discharging the droplet from nozzle N in the recording period Tu[j], the drive signal Vin2 in the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] has a predetermined waveform PH2 regardless of the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux preceding the recording period Tu[j], which is used for determining the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j]. Therefore, when generating the drive signal Vin that matches the state of the meniscus MS at the start time point of the recording period Tu[j], only the waveform of the drive signal Vin1 needs to be adjusted, and the waveform of the drive signal Vin2 does not need to be adjusted.
As described above, it can be said that the liquid discharging head HU executes the drive method including the first step and the second step described below. In the first step, by supplying the drive signal having the waveform PH1 to the piezoelectric element PZ, the liquid column LC6 in which the meniscus MS protrudes in the discharging direction is formed. In the second step, when the liquid column LC6 is formed, by supplying a drive signal having the waveform PH2 to the piezoelectric element PZ, the liquid column LC8 in which the meniscus MS protrudes in the −Z direction is formed, and thereafter a part or all of the ink constituting the liquid column LC8 is discharged as the droplet DR. The waveform PH2 includes two the drive component DC7 that causes the pressure inside the cavity 320 to decrease and the drive component DC8 that causes the pressure inside the cavity 320 to increase. In the second step, by supplying the drive component DC7 to the piezoelectric element PZ before the liquid column LC8 is formed, the meniscus MS forms the liquid column LC7 protruding in the −Z direction. In the second step, when the liquid column LC7 is formed, by supplying the drive component DC8 to the piezoelectric element PZ, the liquid column LC8 is formed.
According to the first embodiment, when the liquid column LC6 is formed, by supplying the drive signal Vin having the drive component DC7 to the piezoelectric element PZ, the liquid column formed in the meniscus MS can be grown, and further, when the liquid column LC7 is formed, by supplying the drive signal Vin having the drive component DC8 to the piezoelectric element PZ, a part or all of the ink constituting the liquid column LC8 can be discharged as the droplet DR.
In the section “Round-up of Relationship between Drive Signal Vin and Meniscus MS”, the waveform PH1 is an example of the “first waveform”. The waveform PH2 is an example of a “second waveform”. The drive component DC7 is an example of a “first pull-in drive component”. The drive component DC8 is an example of a “first push-out drive component”. The liquid column LC6 is an example of the “first liquid column”. The liquid column LC7 is an example of the “third liquid column”. The liquid column LC8 is an example of a “second liquid column”.
The waveform PH1 has three drive pulses PL having a first drive component that causes the pressure inside the cavity 320 to decrease and a second drive component that causes the pressure inside the cavity 320 to increase. In the first step in the section “Round-up of Relationship between Drive Signal Vin and Meniscus MS”, when the drive signal having the drive component DC1 included in the foremost drive pulse PL1 of the three drive pulses PL included in the waveform PH1 is supplied to the piezoelectric element PZ, a liquid surface having a recessed curve surface shape inside the discharging portion D is pulled in toward the +Z direction, and by supplying the drive signal having the drive component DC5 included in the rearmost drive pulse PL3 of the three drive pulses PL included in the waveform PH1 to the piezoelectric element PZ, the meniscus MS, which forms the liquid column LC5 protruding in the −Z direction, is pulled in toward the +Z direction.
According to the first embodiment, in a state in which the drive signal having the drive component DC1 of the first drive pulse PL1 of the waveform PH1 is supplied to the piezoelectric element PZ, the liquid column is not generated in the meniscus MS, and the center part of the meniscus MS has a recessed curve surface shape dented toward the +Z direction side, but by supplying the drive component DC2 of the drive pulse PL1 and the drive components DC3 and DC4 of the drive pulse PL2 to the piezoelectric element PZ, the drive component DC5 of the drive pulse PL3 is supplied to the piezoelectric element PZ, and thus the liquid column LC5 can be formed in the center part of the meniscus MS.
In the section “Round-up of Relationship between Drive Signal Vin and Meniscus MS”, the drive components DC1, DC3, and DC5 are examples of the “first drive components”. The drive components DC2, DC4, and DC6 are examples of the “second drive components”. The meniscus MS forming the liquid column LC5 is an example of the “liquid surface that protrudes in the discharging direction by supplying the first drive component included in the rearmost drive pulse of the plurality of drive pulses included in the first waveform to the drive element”.
In the first step in the section “Round-up of Relationship between Drive Signal Vin and Meniscus MS”, by supplying the drive signal having the drive component DC3 included in the drive pulse PL2 between the foremost drive pulse PL1 and the rearmost drive pulse PL3 among the three drive pulses PL included in the waveform PH1 to the piezoelectric element PZ, the meniscus MS, which forms the liquid column LC3, is pulled in toward the +Z direction. The liquid column LC3 formed by the drive component DC3 of the drive pulse PL2 is smaller than the liquid column LC6 formed by the drive component DC5 of the drive pulse PL3.
In this way, by repeatedly supplying the drive pulse PL to the piezoelectric element PZ, the liquid column can gradually grow large. By growing the liquid column large, even when the ink has a high viscosity, the droplet DR can be discharged when the waveform PH2 is supplied to the piezoelectric element PZ.
The liquid column LC3 is an example of the “fourth liquid column”.
Each of the above embodiments can be modified in various ways. A specific aspect of the modification is exemplified below. Two or more aspects randomly selected from the following exemplifications can be appropriately merged within a range not inconsistent with each other. In the modification examples illustrated below, the elements having the same operations and functions as those of the embodiment will be denoted by the reference numerals referred to in the above description, and detailed description thereof will be appropriately omitted.
In the first embodiment, when the recording period Tu[j] is the non-discharge recording period Tu-N, the control portion 6 generates the individual designation signal Sd[m] of the drive mode α5 but may generate the individual designation signal Sd[m] of the drive mode other than the drive mode α5.
According to the first modification example, even in the recording period Tu[j] that is the non-discharge recording period Tu-N, by supplying the drive pulse PL to the piezoelectric element PZ to the extent that the droplet DR is not discharged, the meniscus MS at the start time point of the next recording period Tu[j+1] of the non-discharge recording period Tu-N can easily maintain the liquid column or can easily form the liquid column in the recording period Tu[j]. When the next recording period Tu[j+1] is the discharge recording period Tu-D, the fluctuation of the meniscus MS in the recording period Tu[j−1] can be used.
In the first modification example, in the non-discharge recording period Tu-N, as the drive pulse PL in which the droplet DR is not discharged, the drive signal Vin2 having the drive pulse PL4 is selected as the drive pulse PL supplied to the piezoelectric element PZ, but the drive pulse PL to be selected is not limited to this. For example, any one of the drive pulses may be selected among the drive pulses PL1, PL2, PL3, PL4, and PL5, or a plurality of drive pulses PL may be selected. However, the drive pulse PL to be selected in the recording period Tu[j], which is the non-discharge recording period Tu-N, is desirably a drive pulse PL close to the drive pulse PL4 in the next recording period Tu[j+1]. This is because when the next recording period Tu[j+1] is the discharge recording period Tu-D, by selecting the drive pulse PL close to the drive pulse PL4 included in the waveform PH2, which is a discharging timing of the droplet DR in the recording period Tu[j+1], as the drive signal Vin for the recording period Tu[j], which is the non-discharge recording period Tu-N, the interval between the drive pulse PL selected within the recording period Tu[j] and the drive pulse PL selected within the recording period Tu[j+1] becomes shorter, and thereby the possibility that the liquid column, which is formed in the meniscus MS in the recording period Tu[j], or the fluctuation in meniscus MS can be used in the recording period Tu[j+1], is increased. Further, when the recording period Tu[j−1] immediately before the recording period Tu[j], which is the non-discharge recording period Tu-N, is the discharge recording period Tu-D, by selecting the drive pulse PL separated from the drive pulse PL4 included in the waveform PH2, which is the discharging timing of the droplet DR in the recording period Tu[j−1] as the drive signal Vin for the recording period Tu[j], the discharging of the droplet DR can be reduced in the recording period Tu[j], which is the non-discharge recording period Tu-N, due to the liquid column, which is formed after discharging the droplet DR in the recording period Tu[j−1], or the fluctuation in meniscus MS.
Further, when the droplet is not discharged from the nozzle N in the recording period Tu[j], the drive signal Vin having at least one of the waveform PH1, which includes at least one of the drive pulses PL1, PL2, and PL3, and, and the waveform PH2, which includes at least one of the drive pulses PL4 and PL5, is supplied to the piezoelectric element PZ so as to increase or decrease the pressure of the ink inside the cavity 320 to the extent that the droplet is not discharged from the nozzle N in the recording period Tu[j]. With the above processes, even in the recording period Tu[j] in which the droplet is not discharged from the nozzle N, by supplying the drive signal Vin having at least one of the waveform PH1 and the waveform PH2 to the piezoelectric element PZ, the vibration of the ink inside the discharging portion D can be maintained in the recording period Tu[j], and the vibration can be used in the recording period Tu[j+1]. In a case where the droplet DR is discharged from the nozzle N in the recording period Tu[j+1], when vibration is applied in the recording period Tu[j] by the waveform PH2 closer to the recording period Tu[j+1], the vibration can be used in the recording period Tu[j+1] before the vibration applied in the recording period Tu[j] become smaller as compared when the vibration is applied in the recording period Tu[j] only by the waveform PH1. Further, in a case where the droplet DR is discharged from the nozzle N in the recording period Tu[j−1], when the drive signal Vin that does not include the waveform PH1 closer to the recording period Tu[j+1] is supplied in the recording period Tu[j], the discharging of the droplet DR can be prevented even in the recording period Tu[j].
In the first embodiment and the first modification example, when the recording period Tu[j] is the non-discharge recording period Tu-N, the control portion 6 at all time generates the individual designation signal Sd[m] having the same drive mode but may generate the individual designation signals Sd[m] having different drive modes between a plurality of non-discharge recording periods Tu-N.
The value indicating the individual designation signal Sd[m] of the drive mode α7 is (0,1,0,0,0). When the individual designation signal Sd[m] indicates the drive mode α7, the coupling state designation circuit 11 sets the coupling state designation signal Sla[m] to a low level in the control period Tcu1, the control period Tcu3, the control period Tcu4, and the control period Tcu5, and sets the coupling state designation signal Sla[m] to a high level in the control period Tcu2. The value indicating the individual designation signal Sd[m] of the drive mode α8 is (1,0,1,0,0). When the individual designation signal Sd[m] indicates the drive mode α8, the coupling state designation circuit 11 sets the coupling state designation signal Sla[m] to a low level in the control period Tcu2, the control period Tcu4, and the control period Tcu5, and sets the coupling state designation signal Sla[m] to a high level in the control period Tcu1 and the control period Tcu3.
Regarding which of the individual designation signal Sd[m] of the drive mode α7 and the individual designation signal Sd[m] of the drive mode α8 is generated, in the second modification example, it is assumed a situation with a continuous non-discharge recording period Tu-N. The control portion 6 generates the individual designation signal Sd[m] of the drive mode α7 in the k-th non-discharge recording period Tu-N among the continuous non-discharge recording period Tu-N and generates the individual designation signal Sd[m] of the drive mode α8 in the (k+1)-th non-discharge recording period Tu-N. The variable “k” is an integer from 1 to the continuous non-discharge recording period Tu-N.
As shown in the second modification example, the control portion 6 may adjust the number of drive pulses PL supplied in the non-discharge recording period Tu-N to the extent that the droplet DR is not discharged in the non-discharge recording period Tu-N. Regarding the specific number of drive pulses PL, the designer of the ink jet printer 1 specifies the relationship between the viscosity and the number of drive pulses PL by experiments and stores in the storage portion 5 a table indicating the relationship between the viscosity of the ink and the number of drive pulses PL or a calculation equation for calculating the number of drive pulses PL by using the viscosity of the ink.
Further, as a modification example of the second modification example, the control portion 6 may change the drive pulse PL supplied in the non-discharge recording period Tu-N to the extent that the droplet DR is not discharged in the non-discharge recording period Tu-N. For example, the control portion 6 may generate the individual designation signal Sd[m] that generates the drive signal Vin having only the drive pulse PL3 in the k-th non-discharge recording period Tu-N among the continuous non-discharge recording periods Tu-N and generate the individual designation signal Sd[m] that generates the drive signal Vin having only the drive pulse PL4 in the (k+1)-th non-discharge recording period Tu-N. The variable “k” is an integer from 1 to the continuous non-discharge recording period Tu-N.
In the first embodiment, the first modification example, and the second modification example, in the stationary state of the discharging portion D where the reference potential V0 is supplied to the piezoelectric element PZ and a state where the position of the meniscus MS is stationary at the initial position Z0, when the drive signal Vin based on the individual designation signal Sd[m] of the drive mode α1 is supplied to the piezoelectric element PZ within one recording period Tu[i], the viscosity of the ink is such that the droplet DR can be discharged within one recording period Tu[i] but even when the drive signal Vin based on the individual designation signal Sd[m] of the drive mode α1 is supplied to the piezoelectric element PZ within the recording period Tu[i], in some cases, the viscosity of the ink has a high viscosity that the ink cannot be discharged within one recording period Tu[i]. In a third modification example, when the printing process starts from the recording period Tu[1], by supplying a drive signal causing nonprint micro-vibration to the piezoelectric element PZ immediately before the recording period Tu[1], the droplet DR can be discharged in the recording period Tu[1], and thereafter, by using the liquid column, which is formed in the meniscus MS in the recording period Tu[j−1], or the fluctuation in meniscus MS, the droplet DR can be discharged in the recording period Tu[j].
Regarding the recording period Tu[1], the control portion 6 generates the individual designation signal Sd[m] of the drive mode α1 and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, the discharging portion D[m] is supplied with the drive signal Vin having the drive pulses PL1, PL2, PL3, PL4, and PL5 in the recording period Tu[1]. The liquid column is formed in the meniscus MS due to the nonprint micro-vibration at the start time point of the recording period Tu[1], or the meniscus MS fluctuates so that the discharging portion D can discharge the droplet DR in the recording period Tu[1].
Regarding the recording period Tu[2], the control portion 6 generates the individual designation signal Sd[m] of the drive mode α2 and outputs the generated individual designation signal Sd[m] to the switching circuit 10. As a result, the discharging portion D[m] is supplied with the drive signal Vin having the drive pulses PL4 and PL5 in the recording period Tu[2]. By supplying the drive signal Vin having the drive pulses PL1, PL2, PL3, PL4, and PL5 in the recording period Tu[1], the liquid column is formed in the meniscus MS at the start time point of the recording period Tu[2], or the meniscus MS fluctuates so that the discharging portion D can discharge the droplet DR in the recording period Tu[1].
The discharge mode illustrated in a second stage in
Regarding the recording period Tu[3], since the preceding predetermined recording period Tux is the non-discharge recording period Tu-N, the drive signal Vin having more drive pulses PL than in the case of the recording period Tu[2], in which the immediately before recording period Tu[1] indicated in the first stage in
In the third modification example, in the first recording period Tu[1] of the printing process, the waveform PH1 included in the drive signal Vin of the nonprint micro-vibration and the recording period Tu[1] is another example of the “first waveform” described in the above-described embodiment and modification examples, and the waveform PH2 included in the drive signal Vin in the recording period Tu[1] is another example of the “second waveform” described in the above-described embodiment and modification examples. Further, in the recording period Tu after the first recording period Tu[1] of the printing process, the waveform PH1 included in the drive signal Vin in the recording period Tu[j−1] and the drive signal Vin in the recording period Tu[j] is another example of the “first waveform” described in the above-described embodiment and modification examples, and the waveform PH2 included in the drive signal Vin in the recording period Tu[j] is another example of the “second waveform” described in the above-described embodiment and modification examples. Further, in the first recording period Tu[1] of the printing process, a plurality of pulses included in the drive signal Vin that causes the nonprint micro-vibration and the drive pulse PL included in the waveform PH1 included in the drive signal Vin in the recording period Tu[1] are other examples of the “first drive pulses” described in the above-described embodiment and modification examples, and the drive pulse PL included in the waveform PH2 included in the drive signal Vin in the recording period Tu[1] is another example of the “second drive pulse” described in the above-described embodiment and modification examples. Further, in the recording period Tu after the first recording period Tu[1] of the printing process, the drive pulse PL included in the drive signal Vin in the recording period Tu[j−1] and the drive pulse PL included in the waveform PH1 included in the drive signal Vin in the recording period Tu[j] are other examples of the “first drive pulses” described in the above-described embodiment and modification examples, and the drive pulse PL included in the waveform PH2 included in the drive signal Vin in the recording period Tu[j] is another example of the “second waveform” described in the above-described embodiment and modification examples.
In the third modification example, an example has been described in which even in a case where the drive signal Vin based on the individual designation signal Sd[m] of the drive mode α1 is supplied to the piezoelectric element PZ within the recording period Tu[i], when the viscosity of the ink has a high viscosity that the ink cannot be discharged within one recording period Tu[i], the droplet DR is discharged in the recording period Tu[1] by supplying the drive signal that causes the nonprint micro-vibration to the piezoelectric element PZ immediately before the first recording period Tu[1] of the printing process, but the present disclosure is not limited to this. In a fourth modification example, from the stationary state of the discharging portion D in which the reference potential V0 is supplied to the piezoelectric element PZ and the state in which the position of the meniscus MS is stationary at the initial position Z0, by supplying the drive signal Vin to the piezoelectric element PZ over the plurality of recording periods Tu[i], it is possible to discharge one droplet DR from the discharging portion D in the plurality of recording periods Tu[i].
In
Subsequently, one dot is printed even in the two of the recording period Tu[i+2] and the recording period Tu[i+3] following the recording period Tu[i+1]. In the recording period Tu[i+2], the control portion 6 generates an individual designation signal Sd[m] having a value (1,1,1,0,0), and in the recording period Tu[i+3], the control portion 6 generates the individual designation signal Sd[m] of the drive mode α1.
In the fourth modification example, the waveform PH1 included in the drive signal Vin in the recording period Tu[i] and the drive signal Vin in the recording period Tu[i+1] are other examples of the “first waveforms” described in the above-described embodiment and modification examples, and the waveform PH2 included in the drive signal Vin in the recording period Tu[i+1] is another example of the “second waveform” described in the above-described embodiment and modification examples. Further, the waveform PH1 included in the drive signal Vin in the recording period Tu[i+2] and the drive signal Vin in the recording period Tu[i+3] are other examples of the “first waveforms” described in the above-described embodiment and modification examples, and the waveform PH2 included in the drive signal Vin in the recording period Tu[i+3] is another example of the “second waveform” described in the above-described embodiment and modification examples. Further, the drive pulse PL included in the drive signal Vin in the recording period Tu[i] and the drive pulse PL included in the waveform PH1 included in the drive signal Vin in the recording period Tu[i+1] are other examples of the “first drive pulses” described in the above-described embodiment and modification examples, and the drive pulse PL included in the waveform PH2 included in the drive signal Vin in the recording period Tu[i+1] is another example of the “second drive pulse” described in the above-described embodiment and modification examples. Further, the drive pulse PL included in the drive signal Vin in the recording period Tu[i+2] and the drive pulse PL included in the waveform PH1 included in the drive signal Vin in the recording period Tu[i+3] are other examples of the “first drive pulses” described in the above-described embodiment and modification examples, and the drive pulse PL included in the waveform PH2 included in the drive signal Vin in the recording period Tu[i+3] is another example of the “second drive pulse” described in the above-described embodiment and modification examples.
As described in the first embodiment, when discharging the droplet DR in the two of the recording period Tu[j] and the recording period Tu[j+1], a waveform of the drive signal Vin supplied to the piezoelectric element PZ in the two of the recording period Tu[j] and the recording period Tu[j+1] is determined based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux preceding the two of the recording period Tu[j] and the recording period Tu[j+1]. Since the droplet DR is discharged in the recording period Tu[i+1] preceding the two of the recording period Tu[i+2] and the recording period Tu[i+3], the number of drive pulses PL included in the drive signal Vin in the recording period Tu[i+2] is smaller than the number of drive pulses PL included in the drive signal Vin in the recording period Tu[i] in which the droplet DR is not discharged in the preceding period.
Further, in the fourth modification example, as in the third modification example, the drive signal that causes the nonprint micro-vibration can be supplied to the piezoelectric element PZ immediately before the start of the printing process. By causing the nonprint micro-vibration before the first recording period Tu[1] of the printing process, as compared with the case where the nonprint micro-vibration is not caused, the number of recording periods Tu corresponding to one dot can be reduced, and the slowdown of the movement speed of the liquid discharging head HU can be reduced.
In the first embodiment and the first modification example to the fourth modification example, when discharging the droplet DR in the recording period Tu[j], the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] is determined based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux preceding the recording period Tu[j], specifically, it is determined which of the drive modes α1 to α4 is selected in the recording period Tu[j] based on the waveform of the drive signal Vin supplied to the piezoelectric element PZ in the predetermined recording period Tux, but the present disclosure is not limited to this. In a fifth modification example, the waveform of the drive signal Vin may be determined based on the viscosity of the ink, specifically, the number of drive pulses PL included in the drive signal Vin may be changed.
The viscosity information acquisition portion 9 acquires viscosity information VI indicating the viscosity of the liquid in the liquid discharging head HU. The viscosity information VI is an example of “physical property information”.
The viscosity information acquisition portion 9 acquires the viscosity information VI by using, for example, any one of the following three methods. In a first method, the viscosity information acquisition portion 9 acquires the viscosity information VI based on the waveform of the residual vibration of the vibrating plate 310. In a second method, the viscosity information acquisition portion 9 acquires the viscosity information VI of the ink contained in the liquid container 14. In a third method, a user inputs the viscosity information VI of the ink, and the viscosity information acquisition portion 9 acquires the viscosity information VI input by the user.
The control portion 6a determines the waveform of the drive signal Vin based on the viscosity information VI. Specifically, the control portion 6a determines the number of drive pulses PL of the waveform PH1 included in the drive signal Vin1 based on the viscosity information VI. An example of determining the number of drive pulses PL of the waveform PH1 included in the drive signal Vin1 will be described with reference to
When the number of drive pulses PL of the waveform PH1 included in the drive signal Vin1 is determined to be one, the control portion 6a determines the waveform of the drive signal Vin1 as the waveform PH1 having any one of the drive pulses PL selected from the drive pulses PL1, PL2, and PL3. For example, the waveform of the drive signal Vin1 is determined to be the waveform PH1 having the drive pulse PL3.
Similarly, when the number of drive pulses PL included in the drive signal Vin1 is determined to be two, the control portion 6a determines the waveform of the drive signal Vin1 as the waveform PH1 having any two of the drive pulses PL selected from the drive pulses PL1, PL2, and PL3. For example, the waveform of the drive signal Vin1 is determined to be the waveform PH1 having the drive pulses PL2 and PL3.
Further, the control portion 6a determines the waveform of the drive signal Vin2 as the waveform PH2 regardless of the viscosity information VI.
In a case where the drive pulse PL to be included in the waveform PH1 is selected from the drive pulses PL1, PL2, and PL3, by selecting the drive pulse PL close to the waveform PH2, the droplet DR can be easily discharged from the nozzle N when the waveform PH2 is supplied to the piezoelectric element PZ.
Referring back to
In the fifth modification example, as further described in the first embodiment, when discharging the droplet DR in the recording period Tu[j], a waveform of the drive signal Vin supplied to the piezoelectric element PZ in the recording period Tu[j] can also be determined in consideration of a waveform of the drive signal Vin supplied to the piezoelectric element PZ in a predetermined recording period Tux preceding the recording period Tu[j].
As described above, in the ink jet printer 1a in the fifth modification example, the control portion 6 executes a recording method including a first step, a second step, a third step, and a fourth step. The first step is to acquire the viscosity information VI indicating the viscosity of the ink in the liquid discharging head HU. The second step is to determine the waveform of the drive signal Vin based on the viscosity information VI. The third step is to form the liquid column LC6 in which the meniscus MS protrudes in the −Z direction by supplying the waveform PH1 included in the drive signal Vin1 among the drive signal Vin having the waveform determined in the second step to the piezoelectric element PZ. In the fourth step, when the liquid column LC6 is formed, by supplying the waveform PH2 included in the drive signal Vin2 among the drive signal Vin having the waveform determined in the second step to the piezoelectric element PZ, the liquid column LC8 in which the meniscus MS protrudes in the −Z direction is formed, and thereafter a part or all of the liquid constituting the liquid column LC8 is discharged as the droplet DR.
When increasing the number of drive pulses PL of the waveform PH1 regardless of the low state of the viscosity of the ink, the droplet DR is discharged earlier than the timing at which the droplet DR should be originally discharged. On the other hand, when decreasing the number of drive pulses PL of the waveform PH1 regardless of the high state of the viscosity of the ink, the droplet DR is discharged later than the timing at which the droplet DR should be originally discharged or the droplet DR is not discharged.
By determining the waveform of the drive signal Vin based on the viscosity indicated in the viscosity information VI, the droplet DR can be discharged so as to approach the timing at which the droplet DR should be originally discharged so that deterioration of the printing quality can be further reduced.
The second step in the “Round-up of Fifth Modification Example” is to determine the waveform of the drive signal Vin1 based on the viscosity information VI.
By adjusting the waveform of the drive signal Vin1, the droplet DR can be discharged so as to approach the timing at which the droplet DR should be originally discharged.
In the second step in the section “Round-up of Fifth Modification Example” is to determine the number of drive pulses PL of the waveform PH1 included in the drive signal Vin1 based on the viscosity information VI.
As described in the section “Round-up of Recording Method Using Drive Waveform Signal Com” in the first embodiment, adjusting the number of drive pulses PL is an easy configuration as compared with an aspect of adjusting the lowest potential and the highest potential of the drive pulses PL.
Therefore, according to the fifth modification example, it is possible to generate the waveform of the drive signal Vin1 that matches the viscosity of the ink with a simpler configuration.
In the fifth modification example, the drive signal Vin2 has a predetermined waveform PH2 regardless of the viscosity information VI. Therefore, when generating the drive signal Vin that matches the viscosity of the ink, it is only necessary to adjust the waveform of the drive signal Vin1 and it is not necessary to adjust the waveform of the drive signal Vin2.
In the second step in the section “Round-up of Fifth Modification Example”, the waveform of the drive signal Vin1 is determined such that a third of the number of drive pulses PL of the waveform PH1 included in the drive signal Vin1 when the viscosity information VI indicates a first viscosity is larger than a fourth of the number of drive pulses PL of the waveform PH1 included in the drive signal Vin1 when the viscosity information VI indicates a second viscosity lower than the first viscosity.
Since the first viscosity is higher than the second viscosity, when the viscosity information VI indicates the first viscosity, it is necessary to supply the drive signal Vin1 having more drive pulses PL to the piezoelectric element PZ as compared when the viscosity information VI indicates the second viscosity. Therefore, the droplet DR can be discharged at the timing at which the droplet DR should be originally discharged by determining the waveform of the drive signal Vin1 such that the third of the number of drive pulses PL is larger than the fourth of the number of drive pulses PL.
In the fifth modification example, it has been described that one example of the physical property information is the viscosity information VI, but the physical property information is not limited to the viscosity information VI. For example, the physical property information may be any one of information indicating the surface tension of the ink, information indicating the bulk modulus of the ink, and information indicating the specific gravity of the ink.
When the physical property information is information indicating the surface tension of the ink, the control portion 6 determines the waveform of the drive signal Vin1 such that the number of drive pulses PL included in the drive signal Vin1 when the surface tension of the ink indicates a first value is larger than the number of drive pulses PL included in the drive signal Vin1 when the surface tension of the ink indicates a second value that is smaller than the first value.
When the physical property information is information indicating the bulk modulus of the ink, the control portion 6 determines the waveform of the drive signal Vin1 such that the number of drive pulses PL included in the drive signal Vin1 when the bulk modulus of the ink indicates a third value is larger than the number of drive pulses PL included in the drive signal Vin1 when the bulk modulus of the ink indicates a fourth value that is smaller than the third value.
When the physical property information is information indicating the specific gravity of the ink, the control portion 6 determines the waveform of the drive signal Vin1 such that the number of drive pulses PL included in the drive signal Vin1 when the bulk modulus of the ink indicates a fifth value is larger than the number of drive pulses PL included in the drive signal Vin1 when the bulk modulus of the ink indicates a sixth value that is smaller than the fifth value.
In the first embodiment and the first modification example to the sixth modification example, the drive waveform signal Com has a waveform PH2 having drive pulses PL4 and PL5, but the present disclosure is not limited to this. A drive waveform signal Comb in a seventh modification example has a waveform PH2b having only the drive pulse PL4.
In the first embodiment and the first modification example to the seventh modification example, a potential difference between the highest potential and the lowest potential in the drive pulses PL included in the waveform PH1 and the waveform PH2 is a potential difference Vh, but the present disclosure is not limited to this. The potential difference of the waveform PH1 may be 0.5 times or more the potential difference of the waveform PH2. In an eighth modification example, a potential difference Vh2a of a drive pulse PL4a included in a waveform PH2a is larger than a potential difference Vh1 of the drive pulses PL1, PL2, and PL3 of the waveform PH1, and a potential difference Vh3a of a drive pulse PL5a included in a waveform PH2 is smaller than the potential difference Vh1 of the drive pulses PL1, PL2, and PL3 of the waveform PH1.
By the potential difference Vh1 of the drive pulses PL1, PL2, and PL3 included in the waveform PH1, any potential can be set suitable for the liquid column to grow appropriately and to prevent the ink from leaking from the nozzle N unnecessarily. Since the liquid column cannot be grown when the potential difference Vh1 is small, the potential difference Vh1 of the drive pulses PL1, PL2, and PL3 is desirably 0.5 times or more the potential difference Vh2a of the drive pulse PL4a of the waveform PH2a.
Further, in the present modification example, the potential difference Vh3a of the drive pulse PL5a of the waveform PH2a is made smaller than the potential difference Vh1 and the potential difference Vh2a. As a result, it is possible to reduce the possibility that the ink oozes out to the surface of the nozzle plate 330 in the −Z direction due to the drive component DC10a of the drive pulse PL5a. When the ink is hard to ooze out to the surface of the nozzle plate 330 in the −Z direction due to the drive component DC10a of the drive pulse PL5a, the potential difference Vh3a of the drive pulse PL5a can be set to the potential difference Vh2a or more.
It is also possible to set the individual potential differences of the drive pulses PL1, PL2, and PL3 of the waveform PH1 to different values from each other.
In the first embodiment and the first modification example to the eighth modification example, a potential difference between the highest potential and the lowest potential in the drive pulses PL included in the waveform PH1 and the waveform PH2 is substantially equal to the potential difference Vh, but the present disclosure is not limited to this. The potential difference of the waveform PH1 may be 0.5 times or more the potential difference of the waveform PH2. In a ninth modification example, the potential difference of the drive pulse PL5 included in the waveform PH2 is larger than the potential difference of the waveform PH1.
According to the ninth modification example, by setting the potential difference of the waveform PH1 to 0.5 times or more the potential difference of the waveform PH2c, the degree of freedom in designing the drive waveform signal Com can be improved as compared with an aspect in which the potential difference of the waveform PH1 and the potential difference of the waveform PH2 are substantially equal to each other. For example, by making the potential difference of the waveform PH2 larger than the potential difference of the waveform PH1, the force for tearing off the droplet DR from the liquid column LC9 can be increased. More desirably, the drive pulse PL5c of the waveform PH2c has the drive component DC9c supplied to the piezoelectric element PZ when the front end of the liquid column LC8 moves in the −Z direction, and the difference between the highest potential and the lowest potential of the drive pulse PL5c is made larger than the difference between the highest potential and the lowest potential in the waveform PH1, and thus the force for tearing off the droplet DR from the liquid column LC9 can be increased.
The drive pulse PL5c is an example of “one drive pulse included in the second drive pulse of the second waveform”, and the drive component DC9c is an example of the “the third drive component supplied to the drive element when the front end of the second liquid column moves in the discharging direction”.
On the other hand, by making the potential difference of the waveform PH1 smaller than the potential difference of the waveform PH2c, the droplet DR can be reliably discharged when the waveform PH2c is supplied to the piezoelectric element PZ, without discharging the droplet DR from the discharging portion D when the waveform PH1 is supplied to the piezoelectric element PZ. Further, when the potential difference of the waveform PH2c is larger than the potential difference of the waveform PH1, the droplets are not excessively discharged by the waveform PH2, but the ink may ooze out to the surface of the nozzle plate 330 in the −Z direction. By making the potential difference of the waveform PH1 larger than the potential difference of the waveform PH2, it is possible to reduce the possibility that the ink oozes out to the surface of the nozzle plate 330 in the −Z direction. The designer of the ink jet printer 1 can design the drive waveform signal Com in consideration of the viscosity of the ink.
In the first embodiment and the first modification example to the ninth modification example, a period from a time point when the supply of the drive components DC9, DC9a, and DC9c included in the drive pulses PL5, PL5a, and PL5c is started to a time point when the supply of the drive components DC10, DC10a, and DC10c is ended, is longer than a period from the time point when the supply of the first drive components DC1, DC3, DC5, and DC7 included in any of the drive pulses PL among the other drive pulses PL included in the drive waveform signals Com, Coma, and Come is started to the time point when the supply of the second drive components DC2, DC4, DC6, and DC8 is ended, but the present disclosure is not limited to this.
Further, the drive pulse PL that causes tearing is one drive pulse PL5, but a plurality of drive pulses PL may be used.
In the first embodiment and the first modification example to the tenth modification example, the highest potential and the initial potential of the drive pulse PL are the same, but the highest potential and the initial potential may be different from each other.
Regarding the drive pulse PLle, the potential at the start is set to the reference potential V0, and the potential at the end is set to the highest potential VH1. The highest potential VH1 is higher than the reference potential V0. The drive pulse PLle has drive components DCle and DC2. Regarding the drive component DCle, the potential at the start is set to the reference potential V0, and the potential at the end is set to the lowest potential VL1. Regarding the drive pulses PL2, PL3, and PL4, the potential at the start and the potential at the end are set to the highest potential VH1. Regarding the drive pulse PL5e, the potential at the start is set to the highest potential VH1, and the potential at the end is set to the reference potential V0. The drive pulse PL5e has drive components DC9 and DC10e. Regarding the drive component DC10e, the potential at the start is set to the lowest potential VL1 and the potential at the end is set to the reference potential V0.
According to the eleventh modification example, a potential difference between the highest potential and the lowest potential of the drive component DC10e is smaller than a potential difference between the highest potential and the lowest potential of the drive component DC10, so that unnecessary discharge can be reduced as compared with the above-described embodiment and modification examples. Alternatively, in the embodiment, there is a possibility that the ink oozes out to the surface of the nozzle plate 330 in the −Z direction even when the droplet DR is not discharged by the drive component DC10. In the tenth modification example, it is possible to reduce the ink from oozing out to the surface of the nozzle plate 330 in the −Z direction as compared with the embodiment.
In the eleventh modification example, the reference potential V0 is between the highest potential VH1 and the lowest potential VL1, but the reference potential V0 may coincide with the lowest potential VL1.
Regarding the drive pulse PL1f, the potential at the start is set to the reference potential V0, and the potential at the end is set to the highest potential VH1. The highest potential VH1 is higher than the reference potential V0. The drive pulse PL1f has the drive component DC2 and does not have the drive component DC1. Regarding the drive pulses PL2, PL3, and PL4, the potential at the start and the potential at the end are set to the highest potential VH1. Regarding the drive pulse PL5f, the potential at the start is set to the highest potential VH1, and the potential at the end is set to the reference potential V0. The drive pulse PL5e has the drive component DC9 and does not have the drive component DC10.
According to the twelfth modification example, since the drive component DC10 is not provided, unnecessary discharge can be reduced as compared with the tenth modification example. Alternatively, in the eleventh modification example, there is a possibility that the ink oozes out to the surface of the nozzle plate 330 in the −Z direction even when the droplet DR is not discharged by the drive component DC10. According to the eleventh modification example, since the drive component DC10 is not provided, it is possible to reduce the ink from oozing out to the surface of the nozzle plate 330 in the −Z direction as compared with the tenth modification example.
In the first embodiment, the control portion 6 determines the waveform of the individual designation signal Sd[m] in the recording period Tu[j] based on the individual designation signals Sd[m] in the recording periods Tu[j−1] to Tu[j−3] as the predetermined recording period Tux preceding the recording period Tu[j], but the present disclosure is not limited to this. For example, the control portion 6 may determine the individual designation signal Sd[m] for the recording period Tu[j] based on the individual designation signals Sd[m] in two or more recording periods Tu, which include the recording period Tu[j−1], are two or more consecutive recording periods Tu, and end before the start of the recording period Tu[j]. Further, for example, the control portion 6 may determine the individual designation signal Sd[m] in the recording period Tu[j] based on the individual designation signal Sd[m] having only the recording period Tu[j−1].
In a fourteenth modification example, it has been described that the control portion 6 determines the individual designation signal Sd[m] in the recording period Tu[j] based on the individual designation signals Sd[m] in two or more recording periods Tu including the recording period Tu[j−1] as the predetermined recording period Tux preceding the recording period Tu[j], but the control portion 6 may determine the individual designation signal Sd[m] in the recording period Tu[j] based on the individual designation signals Sd[m] in one or more recording periods Tu that does not include the recording period Tu[j−1] as the predetermined recording period Tux preceding the recording period Tu[j].
The control portion 6 may determine the waveform of the drive signal Vin in the recording period Tu[j] based on the ratio of the number of recording period Tu in which the droplet DR is discharged from the discharging portion D to the number of recording period Tu in which the droplet DR is not discharged from the discharging portion D among the predetermined recording periods Tux including the recording period Tu[j−1] and including two or more consecutive recording periods Tu ending before the start of the recording period Tu[j]. For example, the control portion 6 calculates the following equation (3).
Discharge ratio=Number of recording periods Tu in which droplet DR is discharged from discharging portion D/Number of predetermined recording periods Tux (3)
Thereafter, the control portion 6 makes the number of drive pulses PL in the recording period Tu when the calculated discharge ratio is a first ratio smaller than the number of drive pulses PL in the recording period Tu when the discharge ratio is a second ratio. The first ratio is larger than the second ratio.
When the discharge ratio is large, the liquid column formed in the meniscus MS at the start time point of the recording period Tu[j] becomes large. Therefore, by determining the waveform of the drive signal Vin in the recording period Tu[j] based on the discharge ratio, the droplet DR can be discharged so as to approach the timing at which the droplet DR should be originally discharged so that deterioration of the printing quality can be further reduced.
In the first embodiment and the first modification example to the fifteenth modification example, the waveform PH1 has three drive pulses PL, but the present disclosure is not limited to this. The waveform PH1 may have only one drive pulse PL or may have four or more drive pulses PL. In a case where the waveform PH1 has four or more drive pulses PL, in the fifth modification example, when the viscosity indicated by the viscosity information VI is 70 millipascal seconds or more, the control portion 6a determines the number of drive pulses PL included in the drive signal Vin1 to be four or more. For example, when the viscosity indicated by the viscosity information VI is 70 millipascal seconds or more and less than 100 millipascal seconds, the control portion 6a determines the number of drive pulses PL included in the drive signal Vin1 to be four.
In the first embodiment, the liquid column is defined as a columnar or pyramidal liquid surface protruding from a position in the most +Z direction side to the −Z direction side in the meniscus MS, but when the droplet is temporarily separated from the meniscus MS, the columnar or pyramidal liquid surface of the droplet may also be the liquid column. A droplet that is temporarily separated from the meniscus MS is a droplet that is separated when a certain drive component DC is supplied but is combined when the next drive component DC is supplied. Specifically, the liquid column LC7 illustrated in
Each of the above aspects can also be applied to an aspect in which a plurality of cavities 320 supply ink to one nozzle N.
Each of the above aspects can be also applied to an ink jet printer 1 that supplies the ink to the liquid discharging head HU and has a circulation mechanism collecting ink discharged from the liquid discharging head HU for resupply to the liquid discharging head HU.
In the nineteenth modification example as well, since the excluded volume of the cavity 320 with respect to one nozzle N can be increased, ink having a higher viscosity can be discharged as compared with the first embodiment. Further, in the nineteenth modification example, the thickening of the ink inside the cavity 320 and the connection flow path 321h is reduced by the circulation mechanism.
In each of the above-described aspects, the serial-type ink jet printer 1 in which a transporting body 82 accommodating the liquid discharging head HU is reciprocated in the X axis direction is exemplified, but the present disclosure is not limited to such an aspect. The ink jet printer may be a line-type ink jet printer in which a plurality of nozzles N are distributed over the entire width of the recording paper P.
When a line-type ink jet printer 1 is used, the third modification example may be applied. The control portion 6 controls the transport mechanism 7 such that the transporting speed of the recording paper P is a value obtained by dividing the transporting speed of the recording paper P by a predetermined number when the twentieth modification example is applied to the first embodiment.
In each of the above aspects, an example of the “drive element” is the piezoelectric element PZ, but a heat generating element may be provided instead of the piezoelectric element PZ.
The ink jet printer exemplified in each of the above-described aspects can be adopted not only in an apparatus dedicated to printing but also in various apparatus such as a facsimile apparatus and a copying machine. Moreover, the application of the liquid discharging apparatus of the present disclosure is not limited to printing. For example, a liquid discharging apparatus that discharges a solution of a coloring material is utilized as a manufacturing apparatus that forms a color filter of a liquid crystal display apparatus. Further, a liquid discharging apparatus that discharges a solution of a conductive material is utilized as a manufacturing apparatus that forms wiring and electrodes of a wiring substrate.
From the above-exemplified embodiment, for example, the following configuration can be ascertained.
A drive method of a liquid discharging head according to Aspect 1, which is a preferred aspect, is a drive method of a liquid discharging head having a discharging portion that includes a drive element that displaces by being supplied with drive signals that include a first drive signal and a second drive signal, a pressure chamber inside which pressure is increased or decreased according to a displacement of the drive element, and a nozzle configured to communicate with the pressure chamber to discharge liquid, which fills inside the pressure chamber, as a droplet in a discharging direction according to an increase or a decrease in the pressure inside the pressure chamber, the drive method including: a first step of acquiring physical property information indicating a physical property of liquid in the liquid discharging head; a second step of determining a waveform of the drive signal based on the physical property information; a third step of forming a first liquid column in which a liquid surface inside the discharging portion protrudes in the discharging direction by supplying a first waveform, which is included in the first drive signal among the drive signals having the waveforms determined in the second step, to the drive element; and a fourth step of, when the first liquid column is formed, forming a second liquid column in which a liquid surface inside the discharging portion protrudes in the discharging direction by supplying a second waveform, which is included in the second drive signal among the drive signals having the waveforms determined in the second step, to the drive element, and thereafter discharging a part or all of liquid constituting the second liquid column as a droplet.
According to Aspect 1, by determining the waveform of the drive signal based on the physical property indicated in the physical property information, the droplet can be discharged so as to approach the timing at which the droplet should be originally discharged so that deterioration of the printing quality can be reduced.
In Aspect 2, which is a specific example of Aspect 1, the physical property information may indicate a viscosity of the liquid in the liquid discharging head.
When increasing the number of drive pulses regardless of the low state of the viscosity of the liquid, the droplet is discharged earlier than the timing at which the droplet should be originally discharged. On the other hand, when decreasing the number of drive pulses regardless of the high state of the viscosity of the liquid, the droplet is discharged later than the timing at which the droplet should be originally discharged or the droplet is not discharged. By determining the waveform of the drive signal based on the viscosity of the liquid indicated in the physical property information, the droplet can be discharged so as to approach the timing at which the droplet should be originally discharged so that deterioration of the printing quality can be reduced.
In Aspect 3, which is a specific example of Aspect 1 or 2, in the second step, a waveform of the first drive signal may be determined based on the physical property information.
According to Aspect 3, by adjusting the waveform of the first drive signal, the droplet can be discharged so as to approach the timing at which the droplet should be originally discharged.
In Aspect 4, which is a specific example of Aspect 3, in the second step, the number of drive pulses of the first waveform included in the first drive signal may be determined based on the physical property information, and the drive pulse may have a drive component that causes the pressure inside the pressure chamber to decrease and a drive component that causes the pressure inside the pressure chamber to increase.
Adjusting the number of drive pulses has a simpler configuration as compared with the aspect of adjusting the lowest potential and the highest potential of the drive pulse. Therefore, according to Aspect 4, it is possible to generate the waveform of the drive signal that matches the viscosity of the liquid with a simpler configuration.
In Aspect 5, which is a specific example of any one of Aspects 1 to 4, the second drive signal may have the second waveform determined in advance regardless of the physical property information.
Therefore, according to Aspect 5, when generating the drive signal that matches the physical property of the liquid, it is only necessary to adjust the waveform of the first drive signal and it is not necessary to adjust the waveform of the second drive signal.
In Aspect 6, which is a specific example of Aspect 2, in the second step, a waveform of the first drive signal may be determined such that the number of drive pulses of the first waveform included in the first drive signal when the physical property information indicates a first viscosity is larger than the number of drive pulses of the first waveform included in the first drive signal when the physical property information indicates a second viscosity that is lower than the first viscosity, and the drive pulse may have a drive component that causes the pressure inside the pressure chamber to decrease and a drive component that causes the pressure inside the pressure chamber to increase.
Since the first viscosity is higher than the second viscosity, when the physical property information indicates the first viscosity, it is necessary to supply the first drive signal having more drive pulses to the drive element as compared when the physical property information indicates the second viscosity. Therefore, according to Aspect 6, the droplet can be discharged at the timing at which the droplet DR should be originally discharged.
In Aspect 7, which is a specific example of any one of Aspects 1 to 6, a viscosity of liquid in the liquid discharging head may be 20 millipascal seconds or more.
When the viscosity of the liquid becomes 20 millipascal seconds or more, it may not be possible to discharge the droplet with only one drive pulse, but according to Aspect 7, the droplet can be discharged even for the liquid that has a viscosity of 20 millipascal seconds or more.
In Aspect 8, which is a specific example of any one of Aspects 1 to 7, a difference between the highest potential and the lowest potential of the first waveform may be substantially equal to a difference between the highest potential and the lowest potential of the second waveform.
By setting the highest potential that can be realized in the liquid discharging apparatus to the highest potential of the first waveform and the second waveform, and setting the lowest potential that can be realized in the liquid discharging apparatus to the lowest potential of the first waveform and the second waveform, even when the liquid has a high viscosity, the liquid column can be grown on the liquid surface inside the discharging portion by the first waveform, and the droplet can be discharged in the second waveform.
A liquid discharging apparatus according to Aspect 9, which is a preferred aspect, is a liquid discharging apparatus including: a liquid discharging head having a discharging portion that includes a drive element that displaces by being supplied with drive signals that include a first drive signal and a second drive signal, a pressure chamber inside which pressure is increased or decreased according to a displacement of the drive element, and a nozzle configured to communicate with the pressure chamber to discharge liquid, which fills inside the pressure chamber, as a droplet in a discharging direction according to an increase or a decrease in the pressure inside the pressure chamber; and a control portion controlling the liquid discharging head, in which the control portion acquires physical property information indicating a physical property of liquid in the liquid discharging head, determines a waveform of the drive signal based on the physical property information, forms a first liquid column in which a liquid surface inside the discharging portion protrudes in the discharging direction by supplying a first waveform, which is included in the first drive signal among the drive signals having the waveforms determined by the control portion, to the drive element, and when the first liquid column is formed, forms a second liquid column in which a liquid surface inside the discharging portion protrudes in the discharging direction by supplying a second waveform, which is included in the second drive signal among the drive signals having the waveforms determined by the control portion, to the drive element, and thereafter discharges a part or all of liquid constituting the second liquid column as a droplet.
According to Aspect 9, by determining the waveform of the drive signal based on the physical property indicated in the physical property information, the droplet can be discharged so as to approach the timing at which the droplet should be originally discharged so that deterioration of the printing quality can be reduced.
Number | Date | Country | Kind |
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2021-038676 | Mar 2021 | JP | national |
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