Patent Application
20240326418
The present application is based on, and claims priority from JP Application Serial Number 2023-054119, filed Mar. 29, 2023, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a liquid ejecting apparatus and a method of driving a liquid ejecting apparatus.
A liquid ejecting apparatus such as an ink jet printer that ejects liquid such as ink from an ejecting section to form an image on a medium such as a recording sheet is widely used. In the liquid ejecting apparatus, an ejection abnormality in which liquid is not normally ejected from the ejecting section may occur, and the quality of an image formed on the medium may decrease due to the ejection abnormality. To recognize such an ejection abnormality, a technique relating to ejection state determination and provided for determining a liquid ejection state of an ejecting section has been proposed. For example, JP-A-2004-276544 describes a technique relating to ejection state determination and provided for determining a liquid ejection state of an ejecting section based on characteristics such as the amplitude and the period of a residual vibration that occurs in the ejecting section driven with a drive signal for inspection.
However, the characteristics of the residual vibration that occurs in the ejecting section driven with the drive signal for inspection may vary due to manufacturing variance in the ejecting section or the like. In addition, the accuracy of determining the liquid ejection state of the ejecting section may decrease due to such variance in the characteristics of the residual vibration.
According to an aspect of the present disclosure, a liquid ejecting apparatus includes an ejecting section that ejects liquid within a pressure chamber according to deformation of a piezoelectric element, a generator that generates an inspection signal that deforms the piezoelectric element, and a vibration detector that detects a residual vibration occurring in the ejecting section after the inspection signal is supplied to the piezoelectric element. The inspection signal includes a first potential-changing element having a potential that changes from a first potential to a second potential in one direction in a first time period, a first potential-maintaining element having the second potential maintained in a second time period immediately after the first time period, a second potential-changing element having a potential that changes from the second potential to a third potential in the other direction in a third time period immediately after the second time period, and a second potential-maintaining element having the third potential maintained in a fourth time period immediately after the third time period. When a natural vibration period of the ejecting section is TC, a length of the first time period is equal to or longer than 0.75×TC. The vibration detector detects the residual vibration in a detection period included in the fourth time period.
According to another aspect of the present disclosure, a method of driving a liquid ejecting apparatus including an ejecting section that ejects liquid within a pressure chamber according to deformation of a piezoelectric element, a generator that generates an inspection signal that deforms the piezoelectric element, and a vibration detector that detects a residual vibration occurring in the ejecting section after the inspection signal is supplied to the piezoelectric element. The method includes causing the generator to generate the inspection signal including a first potential-changing element having a potential that changes from a first potential to a second potential in one direction in a first time period, a first potential-maintaining element having the second potential maintained in a second time period immediately after the first time period, a second potential-changing element having a potential that changes from the second potential to a third potential in the other direction in a third time period immediately after the second time period, and a second potential-maintaining element having the third potential maintained in a fourth time period immediately after the third time period, and causing the vibration detector to detect the residual vibration in a detection period included in the fourth time period. When a natural vibration period of the ejecting section is TC, a length of the first time period is equal to or longer than 0.75×TC.
Embodiments of the present disclosure are described below with reference to the drawings. However, in the drawings, dimensions and scales of components are different from those of the actual components as appropriate. In addition, since the embodiments described below are specific examples of the present disclosure, various technically preferable limitations are given. However, the scope of the present disclosure is not limited to the embodiments unless otherwise stated to limit the present disclosure in the following description.
A first embodiment describes a liquid ejecting apparatus while exemplifying an ink jet printer that ejects ink to form an image on a recording sheet P. In the first embodiment, the ink is an example of “liquid”, and the recording sheet P is an example of a “medium”. The ink jet printer 1 according to the first embodiment is described below with reference to
As illustrated in
As illustrated in
In the present embodiment, it is assumed that the ink jet printer 1 includes one or more head units 3, one or more drive signal generating units 4 corresponding to the one or more head units 3 on a one-to-one basis, and one or more determining units 8 corresponding to the one or more head units 3 on a one-to-one basis. However, for convenience of explanation, as illustrated in
The control unit 2 includes one or more central processing units (CPUs). However, the control unit 2 may include a programmable logic device such as a field-programmable gate array (FPGA) instead of or in addition to the one or more CPUs. In addition, the control unit 2 includes, for example, either one or both of a volatile memory such as a random-access memory (RAM) and a nonvolatile memory such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM) or a programmable ROM (PROM).
The control unit 2 generates signals for controlling an operation of each of the components of the ink jet printer 1. The signals are a print signal SI, a waveform specifying signal dCom, and the like, which are described later in detail.
The waveform specifying signal dCom is a digital signal defining a waveform of a drive signal Com. The drive signal Com is an analog signal for driving the ejecting section D. In the present embodiment, it is assumed that the drive signal Com includes a drive signal Com-A and a drive signal Com-B. The drive signal generating unit 4 includes a DA conversion circuit and generates the drive signal Com having the waveform defined by the waveform specifying signal dCom. The print signal SI is a digital signal for specifying a type of operation of the ejecting section D. Specifically, the print signal SI is a signal specifying the type of operation of the ejecting section D by specifying whether to supply the drive signal Com to the ejecting section D. The drive signal generating unit 4 is an example of a “generator”.
As illustrated in
The recording head 32 includes a number M of ejecting sections D. The value M is a natural number satisfying “M≥1”. The recording head 32 is an example of a “liquid ejecting head”. An m-th ejecting section D among the number M of ejecting sections D included in the recording head 32 may be hereinafter referred to as an ejecting section D[m]. The variable m is a natural number satisfying “1≤m≤M”. In addition, when a component, a signal, or the like of the ink jet printer 1 corresponds to the ejecting section D[m] among the number M of ejecting sections D, an index [m] may be added to a reference sign representing the component, the signal, or the like.
The supply circuit 31 switches, based on the print signal SI, whether to supply a drive signal Com to the ejecting section D[m]. The drive signal Com to be supplied to the ejecting section D[m] among drive signals Com may be hereinafter referred to as a supply drive signal Vin[m]. In addition, the supply circuit 31 switches, based on the print signal SI, whether to supply a detection potential signal VX[m] indicating a potential of an upper electrode Zu[m] of a piezoelectric element PZ[m] included in the ejecting section D[m] to the detecting circuit 33.
When the detection potential signal VX[m] is to be supplied from the ejecting section D[m] to the detecting circuit 33, the ejecting section D[m] may be hereinafter referred to as a determination target ejecting section DS.
The piezoelectric element PZ[m] and the upper electrode Zu[m] are described later with reference to
The detecting circuit 33 generates a detection signal SK[m] based on the detection potential signal VX[m] supplied from the determination target ejecting section DS through the supply circuit 31. Specifically, the detecting circuit 33 generates the detection signal SK[m] by, for example, amplifying the detection potential signal VX[m] and removing a noise component from the detection potential signal VX[m].
The temperature detector 5 detects the temperature of the head unit 3 including the ejecting section D. In addition, the temperature detector 5 generates a temperature detection signal TI indicating the detected temperature and supplies the generated temperature detection signal TI to the control unit 2.
The determining unit 8 determines, based on the detection signal SK[m], whether an ink ejection state of the ejecting section D[m] is normal or whether the ejecting section D[m] is in a normal ejection state in which an ejection abnormality does not occur. The determining unit 8 generates ejection state determination information JH[m] indicating a result of the determination. The ejection abnormality means that the ink ejection state of the ejecting section D[m] is abnormal. That is, the ejection abnormality is a general term for a state in which the ejecting section D[m] cannot appropriately eject the ink from a nozzle N included in the ejecting section D[m]. For example, the ejection abnormality includes a state in which the ink cannot be ejected from the ejecting section D[m], a state in which the ejecting section D[m] ejects the ink in an amount different from an ink ejection amount defined by the drive signal Com, and a state in which the ejecting section D[m] ejects the ink at a speed different from an ink ejection speed defined by the drive signal Com. Processing relating to the determination of the ink ejection state of the ejecting section D[m] may be hereinafter referred to as ejection state determination processing. That is, the determination target ejecting section DS is the ejecting section D[m] to be subjected to the ejection state determination processing.
When the print processing is performed, the control unit 2 generates, based on the print data Img, a signal for controlling the head unit 3, such as the print signal SI. In addition, when the print processing is performed, the control unit 2 generates a signal for controlling the drive signal generating unit 4, such as the waveform specifying signal dCom. Furthermore, when the print processing is performed, the control unit 2 generates a signal for controlling the transport unit 7. As a result of the generation of the signals, in the print processing, the control unit 2 controls the transport unit 7 to change a relative position of the recording sheet P to the head unit 3, controls whether the ejecting section D[m] ejects the ink, an amount of the ink to be ejected, a timing of ejecting the ink, and the like, and controls the components of the ink jet printer 1 in such a way that the image corresponding to the print data Img is formed on the recording sheet P.
As illustrated in
Hereinafter, a +X direction and a —X direction opposite to the +X direction are collectively referred to as an “X-axis direction”, a +Y direction intersecting the X-axis direction and a −Y direction opposite to the +Y direction are collectively referred to as a “Y-axis direction”, and a +Z direction intersecting the X-axis direction and the Y-axis direction and a −Z direction opposite to the +Z direction are collectively referred to as a “Z-axis direction”. In the present embodiment, as illustrated in
As illustrated in
In the present embodiment, as illustrated in
In addition, as described above, the ink jet printer 1 according to the present embodiment includes the transport unit 7. As illustrated in
As illustrated in
As illustrated in
A configuration of each of the head units 3 is described below with reference to
As illustrated in
As illustrated in
The coupling state specifying circuit 310 generates, based on at least one of the print signal SI, a latch signal LAT, a time period specifying signal Tsig, and a change signal CH supplied from the control unit 2, a first coupling state specifying signal Qa[m] specifying turning on or off of the switch Wa[m], a second coupling state specifying signal Qb[m] specifying turning on or off of the switch Wb[m], and a third coupling state specifying signal Qs[m] specifying turning on or off of the switch Ws[m].
The switch Wa[m] switches, based on the first coupling state specifying signal Qa[m], whether to set the wire line La to be electrically conductive to the upper electrode Zu[m] of the piezoelectric element PZ[m] disposed in the ejecting section D[m]. In the present embodiment, the switch Wa[m] is on when the first coupling state specifying signal Qa[m] is at a high level. In the present embodiment, the switch Wa[m] is off when the first coupling state specifying signal Qa[m] is at a low level. When the switch Wa[m] is on, the drive signal Com-A supplied to the wire line La is supplied as the supply drive signal Vin[m] to the upper electrode Zu[m] of the ejecting section D[m].
In addition, the switch Wb[m] switches, based on the second coupling state specifying signal Qb[m], whether to set the wire line Lb to be electrically conductive to the upper electrode Zu[m] of the piezoelectric element PZ[m] disposed in the ejecting section D[m]. In the present embodiment, the switch Wb[m] is on when the second coupling state specifying signal Qb[m] is at a high level. In the present embodiment, the switch Wb[m] is off when the second coupling state specifying signal Qb[m] is at a low level. When the switch Wb[m] is on, the drive signal Com-B supplied to the wire line Lb is supplied as the supply drive signal Vm[m] to the upper electrode Zu[m] of the ejecting section D[m].
In addition, the switch Ws[m] switches, based on the third coupling state specifying signal Qs[m], switches whether to set the wire line Ls to be electrically conductive to the upper electrode Zu[m] of the piezoelectric element PZ[m] disposed in the ejecting section D[m]. In the present embodiment, the switch Ws[m] is on when the third coupling state specifying signal Qs[m] is at a high level. In the present embodiment, the switch Ws[m] is off when the third coupling state specifying signal Qs[m] is at a low level. When the switch Ws[m] is on, the potential of the upper electrode Zu[m] of the ejecting section D[m] is supplied as the detection potential signal VX[m] to the detecting circuit 33 through the wire line Ls.
In addition, the detecting circuit 33 generates, based on the detection potential signal VX[m] supplied from the wire line Ls, the detection signal SK[m] having a waveform corresponding to the waveform of the detection potential signal VX[m].
An operation of the head unit 3 is described below with reference to
In the present embodiment, when the ink jet printer 1 performs the print processing or the ejection state determination processing, one or more unit time periods TP are set as an operation period of the ink jet printer 1. The ink jet printer 1 according to the present embodiment can drive each ejecting section D[m] for the print processing or the ejection state determination processing in each unit time period TP.
As illustrated in
In addition, the control unit 2 outputs the change signal CH having a pulse PLC in the unit time period TP. Then, the control unit 2 divides the unit time period TP into a control period TQ1 from the rising edge of the pulse PLL to a rising edge of the pulse PLC and a control period TQ2 from the rising edge of the pulse PLC to the next rising edge of the pulse PLL.
Furthermore, the control unit 2 outputs the time period specifying signal Tsig having a pulse PLT1 and a pulse PLT2. Then, the control unit 2 divides the unit time period TP into a control period TSS1 from the rising edge of the pulse PLL to a rising edge of the pulse PLT1, a control period TSS2 from the rising edge of the pulse PLT1 to a rising edge of the pulse PLT2, and a control period TSS3 from the rising edge of the pulse PLT2 to the next rising edge of the pulse PLL.
The print signal SI according to the present embodiment includes a number M of individual specifying signals Sd[1] to Sd[M] corresponding to the number M of ejecting sections D[1] to D[M] on a one-to-one basis. In the print processing or the ejection state determination processing performed by the ink jet printer 1, the individual specifying signal Sd[m] specifies a mode of driving the ejecting section D[m] in each unit time period TP.
As illustrated in
In the present embodiment, it is assumed that the ejecting section D[m] can form any one of a large dot, a middle dot smaller than the large dot, and a small dot smaller than the middle dot in the unit time period TP. In the present embodiment, it is assumed that the individual specifying signal Sd[m] can take any one of a value “1” specifying the ejecting section D[m] as a large dot formation ejecting section DP-1 that ejects ink in an amount corresponding to the large dot, a value “2” specifying the ejecting section D[m] as a middle dot formation ejecting section DP-2 that ejects ink in an amount corresponding to the middle dot, a value “3” specifying the ejecting section D[m] as a small dot formation ejecting section DP-3 that ejects ink in an amount corresponding to the small dot, a value “4” specifying the ejecting section D[m] as a non-dot formation ejecting section DP-4 that is a non-determination target ejecting section DS that does not eject ink, and a value “5” specifying the ejecting section D[m] as the determination target ejecting section DS.
As illustrated in
In the present embodiment, the amount ξ1 of ink corresponds to the middle dot. In the present embodiment, the amount ξ2 of ink is smaller than the amount ξ1 of ink and corresponds to the small dot. In the present embodiment, the total of the amount ξ1 of ink and the amount ξ2 of ink is an amount of ink corresponding to the large dot.
In the present embodiment, as an example, it is assumed that the potential of the supply drive signal Vin[m] supplied to the ejecting section D[m] is at a high level, the capacity of the cavity 322 included in the ejecting section D[m] decreases, as compared with a case where the potential of the supply drive signal Vin[m] is at a low level. Therefore, when the ejecting section D[m] is driven with the supply drive signal Vin[m] having the waveform PP1 or the waveform PP2, the potential of the supply drive signal Vin[m] changes from the low level to the high level and thus the ink within the ejecting section D[m] is ejected from the nozzle N.
As illustrated in
As described later with reference to
As described later with reference to
In the example illustrated in
In the present embodiment, as an example, it is assumed that the waveform PS is defined in such a way that when the supply drive signal Vin[m] having the waveform PS is supplied to the ejecting section D[m], the ink is not ejected from the ejecting section D[m].
As illustrated in
In addition, when the individual specifying signal Sd[m] indicates the value “2” specifying the ejecting section D[m] as the middle dot formation ejecting section DP-2 in the time period TP, the coupling state specifying circuit 310 sets the first coupling state specifying signal Qa[m] to a high level for the control period TQ1. In this case, the switch Wa[m] is on for the control period TQ1. Therefore, the ejecting section D[m] is driven with the supply drive signal Vin[m] having the waveform PP1 and ejects the ink in the amount corresponding to the middle dot in the unit time period TP.
When the individual specifying signal Sd[m] indicates the value “3” specifying the ejecting section D[m] as the small dot formation ejecting section DP-3 in the unit time period TP, the coupling state specifying circuit 310 sets the first coupling state specifying signal Qa[m] to a high level for the control period TQ2. In this case, the switch Wa[m] is on for the control period TQ2. Therefore, the ejecting section D[m] is driven with the supply drive signal Vin[m] having the waveform PP2 and ejects the ink in the amount corresponding to the small dot in the unit time period TP.
When the individual specifying signal Sd[m] indicates the value “4” specifying the ejecting section D[m] as the non-dot formation ejecting section DP-4 in the unit time period TP, the coupling state specifying circuit 310 sets the first coupling state specifying signal Qa[m], the second coupling state specifying signal Qb[m], and the third coupling state specifying signal Qs[m] to a low level for the unit time period TP. In this case, the switch Wa[m], the switch Wb[m], and the switch Ws[m] are off for the unit time period TP. Therefore, for the unit time period TP, the supply drive signal Vin[m] is not supplied to the ejecting section D[m] and the ink is not ejected from the ejecting section D[m].
When the individual specifying signal Sd[m] indicates the value “5” specifying the ejecting section D[m] as the determination target ejecting section DS in the unit time period TP, the coupling state specifying circuit 310 sets the second coupling state specifying signal Qb[m] to a high level for the control period TSS1 and the control period TSS3 and sets the third coupling state specifying signal Qb[m] to a high level in the control period TSS2. In this case, the switch Wb[m] is on for the control period TSS1 and the control period TSS3, and the switch Ws[m] is on for the control period TSS2. Therefore, when a vibration occurs in the ejecting section D[m] as a result of the driving of the ejecting section D[m] specified as the determination target ejecting section DS with the supply drive signal Vin[m] having the waveform PS1 and the waveform PS3 in the control period TSS1, the vibration remains in the control period TSS2. In the control period TSS2, when the vibration remains in the ejecting section D[m], the potential of the upper electrode Zu[m] included in the ejecting section D[m] changes. Then, in the control period TSS2, when the vibration remains in the ejecting section D[m], the potential of the upper electrode Zu[m] is supplied as the detection potential signal VX[m] to the detecting circuit 33 through the switch Ws[m].
That is, the waveform of the detection potential signal VX[m] detected from the ejecting section D[m] in the control period TSS2 indicates the waveform of the vibration remaining in the ejecting section D[m] in the control period TSS2. Then, the waveform of the detection signal SK[m] generated based on the detection potential signal VX[m] detected from the ejecting section D[m] in the control period TSS2 indicates the waveform of the vibration remaining in the ejecting section D[m] in the control period TSS2. The detecting circuit 33 detects the vibration remaining in the ejecting section D[m] in a detection period included in the time period TPS4 within the control period TSS2. The detecting circuit 33 is an example of a “vibration detector”.
The determining unit 8 determines, based on characteristics such as the amplitude, the period, and the like of the residual vibration indicated by the detection signal SK[m] supplied from the detecting circuit 33, whether the ink ejection state of the ejecting section D[m] is normal. Then, the determining unit 8 generates the ejection state determination information JH[m] indicating a result of determining the ink ejection state.
Details of the drive signal Com-B are described below with reference to
In the present embodiment, the time period TPS1 from the start of the waveform PS1 included in the drive signal Com-B to the end of the waveform PS1 included in the drive signal Com-B is determined based on a natural vibration period TC of the ejecting section D. In the present embodiment, as an example, it is assumed that the natural vibration period TC is an average value of natural vibration periods of the number M of ejecting sections D[1] to D[M] included in the recording head 32. The natural vibration period of the ejecting section D[m] among the natural vibration periods of the number M of ejecting sections D[1] to D[M] is a period of a residual vibration detected from the ejecting section D[m] driven with the drive signal Com-B or the like when the ink ejection state of the ejecting section D[m] is normal. For example, the natural vibration period of the ejecting section D[m] may be a period of a residual vibration detected from the ejecting section D[m] driven with the drive signal Com-B or the like in the ejection state determination processing performed in quality inspection before shipment of the ink jet printer 1.
However, the present disclosure is not limited thereto. For example, as the natural vibration period of the ejecting section D, an average value of natural vibration periods of a plurality of ejecting sections D included in a plurality of ink jet printers 1 may be used.
In addition, for example, the natural vibration period TC of the ejecting section D may be determined based on an average value of usage periods of the number M of ejecting sections D[1] to D[M] that is indicated by characteristic information relating to the characteristics of the piezoelectric element PZ[m]. In this case, the natural vibration period TC of the ejecting section D may be determined based on information stored in a storage device (not illustrated) and indicating a relationship between the usage period of the ejecting section D and the natural vibration period of the ejecting section D. Examples of the characteristic information relating to the characteristics of the piezoelectric element PZ[m] are a cumulative energization time that is a cumulative time when a drive signal Com is supplied to the head unit 3 in a predetermined time period from shipment of the ink jet printer 1 as a product to the current time, and the number of supplied pulses of the drive signal Com. The longer the cumulative energization time as the characteristic information, the longer the usage period of the ejecting section D. In addition, the larger the number of supplied pulses of the drive signal Com as the characteristic information, the longer the usage period of the ejecting section D. As an example, the control unit 2 calculates the cumulative energization time by multiplying the length of the unit time period TP by the counted number of pulses PLL of the latch signal LAT. As an example, the control unit 2 counts the number of supplied pulses of the drive signal Com-A based on the print signal SI. The control unit 2 acquires the cumulative energization time or the number of supplied pulses of the drive signal Com as the characteristic information relating to the characteristics of the piezoelectric element PZ[m]. The control unit 2 is an example of an “acquirer”.
For example, a natural vibration period of any one of the number M of ejecting sections D[1] to D[M] may be used as the natural vibration period TC of the ejecting section D. The natural vibration period TC may be hereinafter merely referred to as “TC”.
In
In an existing technique, in ejection state determination processing of determining an ink ejection state of an ejecting section D[m], to detect a residual vibration occurring in the ejecting section D[m], a drive signal Com-B is supplied to a piezoelectric element PZ[m included in the ejecting section D[m] to deform the piezoelectric element PZ[m] before the detection of the residual vibration as described above. When the deformation of the piezoelectric element PZ[m] is large, it is possible to improve the accuracy of the determination in the ejection state determination processing based on the residual vibration occurring in the ejecting section D[m], as compared with a case where the deformation of the piezoelectric element PZ[m] is small. Therefore, in the existing technique, in the ejection state determination processing, to increase the deformation of the piezoelectric element PZ[m], the potential of the drive signal Com-B to be supplied to the ejecting section D[m] is changed from a reference voltage VO to a certain voltage in one direction and is changed from the certain voltage in the other direction. In this case, in the ejection state determination processing, the ink ejection state of the ejecting section D[m] is determined based on the residual vibration in which a vibration occurring in the ejecting section D[m] due to the change in the potential of the drive signal Com-B in the one direction overlaps another vibration occurring in the ejecting section D[m] due to the change in the potential of the drive signal Com-B in the other direction. However, due to manufacturing variance in the ejecting section D[m] or the like, the characteristics of the residual vibration occurring in the ejecting section D[m] may vary.
Specifically, due to a manufacturing error occurring in the ejecting section D[m] or the like, an effect of one vibration occurring in the ejecting section D[m] due to a change in the potential of the drive signal Com-B to one side on another vibration occurring in the ejecting section D[m] due to a change in the potential of the drive signal Com-B to the other side varies. Due to the effect that varies, the characteristics of the residual vibration occurring in the ejecting section D[m] driven with the drive signal Com-B vary.
When the characteristics of the residual vibration occurring in the ejecting section D[m] largely vary, the accuracy of the determination in the ejection state determination processing decreases.
Particularly, when “vibration suppression” occurs in such a way that one vibration occurring in the ejecting section D[m] due to a change in the potential of the drive signal Com-B to one side and another vibration that occurring in the ejecting section D[m] due to a change in the potential of the drive signal Com-B to the other side cancel each other, the amplitude of the residual vibration detected in the ejection state determination processing is smaller, as compared with a case where the “vibration suppression” does not occur. Therefore, the accuracy of the ejection state determination processing performed based on the residual vibration decreases.
When “resonance” occurs in such a way that one vibration occurring in the ejecting section D[m] and another vibration occurring in the ejecting section D[m] strengthen each other, there may be a problem that a risk of erroneously ejecting ink from the ejecting section D[m] increases, as compared with a case where the “resonance” does not occur.
In the present embodiment, when the length of the time period TPS1 is set to a length of 0.75×TC or more, it is possible to suppress a vibration caused by the waveform PS1 in the ejecting section D[m] to which the drive signal Com-B is supplied, as compared with a case where the length of the time period TPS1 is set to a length of less than 0.75×TC. As a result, according to the present embodiment, an effect of a vibration caused by the waveform PS1 on a vibration caused by the waveform PS3 in the ejecting section D[m] to which the drive signal Com-B is supplied is suppressed, as compared with a case where the length of the time period TPS1 is set to a length of less than 0.75×TC. Therefore, the ink jet printer 1 according to the present embodiment can accurately determine the ejection state of the ejecting section D[m], as compared with a case where the length of the time period TPS1 is set to a length of less than 0.75×TC.
In the graph illustrated in
In the graph illustrated in
When a unit time period Δt of each of the step-like waveforms is 0.05 μs, the amplitude fn of the vibration caused by the n-th step-like waveform is calculated according to the following Equation (2), where t1 that is a start time of the n-th step-like waveform is Δt×n, A is a default value of the amplitude, and T is a time variable relating to the attenuation of the amplitude A.
A=Δt/TPS1. In Equation (2),
In the graph illustrated in
In the graph illustrated in
The graphs illustrated in
In
The control unit 2 corrects the waveform specifying signal dCom according to the temperature indicated by the temperature detection signal TI acquired from the temperature detector 5. The drive signal generating unit 4 corrects the length of the time period TPS1 based on the corrected waveform specifying signal dCom. In other words, the drive signal generating unit 4 corrects the length of the time period TPS1 according to the temperature detected by the temperature detector 5.
The higher the temperature of the head unit 3, the higher the temperature of the cavity 322 included in the ejecting section D[m] in the head unit 3. As a result, the temperature of the ink with which the cavity 322 is filled increases and the viscosity of the ink decreases. When the viscosity of the ink decreases, the length of the natural vibration period increases. As the length of the natural vibration period increases, the drive signal generating unit 4 increases the length of the time period TPS1. On the other hand, when the temperature of the head unit 3 decreases, the drive signal generating unit 4 reduces the length of the time period TPS1.
The drive signal generating unit 4 corrects the length of the time period TPS1 according to the reference potential VO. As described above, when the temperature of the ink with which the cavity 322 is filled increases, the viscosity of the ink decreases and the value of the potential VS1 illustrated in
The control unit 2 corrects the waveform specifying signal dCom according to the characteristic information acquired as the acquirer. The drive signal generating unit 4 corrects the length of the time period PS1 based on the corrected waveform specifying signal dCom. In other words, the drive signal generating unit 4 corrects the length of the time period TPS1 according to the characteristic information acquired by the control unit 2. Specifically, it is expected that the longer the cumulative energization time indicated by the characteristic information, the longer the natural vibration period due to degradation of the piezoelectric element PZ[m] over time. Therefore, the drive signal generating unit 4 increases the length of the time period TPS1 as the cumulative energization time increases.
However, as the piezoelectric element PZ[m] degrades over time, the length of the natural vibration period may decrease, depending on the material of the piezoelectric element PZ[m]. In this case, the drive signal generating unit 4 reduces the length of the time period TPS1 as the length of the cumulative energization time increases. Similarly, the drive signal generating unit 4 increases the length of the time period TPS1 as the number of supplied pulses indicated by the characteristic information increases. However, as the piezoelectric element PZ[m] degrades over time, the length of the natural vibration period may decrease, depending on the material of the piezoelectric element PZ[m]. In this case, the drive signal generating unit 4 reduces the length of the time period TPS1 as the number of supplied pulses increases.
In
In
In
Since the length of the time period TPS5 is equal to or longer than 0.75×TC, it is possible to suppress an effect of a vibration caused by a change in the potential represented by the waveform PS5 from the potential VS2 to the reference potential VO on the ejecting section D adjacent to the determination target ejecting section DS. In addition, since the length of the time period TPS5 is equal to or longer than 0.75×TC, it is possible to suppress ejection of an unexpected droplet from the determination target ejecting section DS.
Alternatively, in
In the determination of the ejection state of the ejecting section D[m], an effect of one vibration caused by a change in the potential represented by the waveform PS1 from the reference potential VO to the potential VS1 is larger than an effect of another vibration caused by a change in the potential represented by the waveform PS5 from the potential VS2 to the reference potential VO. Therefore, when the length of the time period TPS1 corresponding to the waveform PS1 is relatively longer than the length of the time period TPS5 corresponding to the waveform PS5, the ink jet printer 1 according to the present embodiment can accurately determine the ejection state of the ejecting section D[m], as compared with the existing techniques.
As described above, the ink jet printer 1 as the liquid ejecting apparatus according to the present embodiment includes the ejecting section D, the drive signal generating unit 4 as the generator, and the detecting circuit 33 as the vibration detector.
The ejecting section D ejects liquid within the cavity 322 as a pressure chamber according to deformation of the piezoelectric element PZ[m]. The drive signal generating unit 4 generates the drive signal Com-B as an inspection signal that deforms the piezoelectric element PZ[m]. The detecting circuit 33 detects a residual vibration occurring in the ejecting section D after the drive signal Com-B is supplied to the piezoelectric element PZ[m]. The drive signal Com-B includes the waveform PS1 as a first potential-changing element having a potential that changes from the reference voltage VO as a first potential to the potential VS1 as a second potential in one direction in the time period TPS1 as a first time period, the waveform PS2 as a first potential-maintaining element having the potential VS1 maintained in the time period TPS2 as a second time period immediately after the time period TPS1, the waveform PS3 as a second potential-changing element having a potential that changes from the potential VS1 to the potential VS2 as a third potential in the other direction in the time period TPS3 as a third time period immediately after the time period TPS2, and the waveform PS4 as a second potential-maintaining element having the potential VS2 maintained in the time period TPS4 as a fourth time period immediately after the time period TPS3. When the natural vibration period of the ejecting section D is TC, the length of the time period TPS1 as the first time period is equal to or longer than 0.75×TC. The detecting circuit 33 as the vibration detector detects the residual vibration in the detection period included in the time period TPS4 as the fourth time period.
Therefore, the ink jet printer 1 can suppress variance in the characteristics of the residual vibration and improve the accuracy of determining the liquid ejection state of the ejecting section D[m], as compared with a case where the length of the time period TPS1 is shorter than 0.75×TC.
In the ink jet printer 1 according to the present embodiment, the reference voltage VO as the first potential is between the potential VS1 as the second potential and the potential VS2 as the third potential.
Therefore, the ink jet printer 1 can significantly deform the piezoelectric element PZ[m] included in the ejecting section D[m].
In the ink jet printer 1 according to the present embodiment, when a number N is a natural number of 1 or more, the time period TPS1 as the first time period is equal to or longer than 0.75×N×TC and equal to or shorter than 1.25×N×TC.
Therefore, the ink jet printer 1 can suppress variance in the characteristics of the residual vibration and improve the accuracy of determining the liquid ejection state of the ejecting section D[m], as compared with a case where the length of the time period TPS1 is shorter than 0.75×TC.
In the ink jet printer 1 according to the present embodiment, the number N is 1 or 2.
Therefore, the ink jet printer 1 can suppress variance in the characteristics of the residual vibration and improve the accuracy of determining the liquid ejection state of the ejecting section D[m], as compared with a case where the length of the time period TPS1 is shorter than 0.75×TC.
In the ink jet printer 1 according to the present embodiment, the length of the time period TPS2 as the second time period is equal to or longer than the length of the natural vibration period TC.
Therefore, when the length of the time period TPS2 is equal to or longer than the length of the natural vibration period TC, variance in the characteristics of a residual vibration caused by a change in the potential represented by the waveform PS1 to one side is significantly suppressed.
The ink jet printer 1 according to the present embodiment further includes the temperature detector 5 that detects the temperature of the head unit 3 including the ejecting section D. The drive signal generating unit 4 as the generator corrects the length of the time period TPS1 as the first time period according to the temperature detected by the temperature detector 5.
Therefore, as the temperature detected by the temperature detector 5 increases, the temperature of the cavity 322 included in the ejecting section D in the head unit 3 increases and the viscosity of the ink with which the cavity 322 is filled decreases. The drive signal generating unit 4 can correct the length of the time period TPS1 according to the decrease in the viscosity of the ink.
In the ink jet printer 1 according to the present embodiment, the drive signal generating unit 4 as the generator corrects the length of the time period TPS1 as the first time period according to the reference potential VO as the first potential.
Therefore, when the temperature of the ink with which the cavity 322 is filled increases, the value of the reference potential VO decreases. The drive signal generating unit 4 can correct the length of the time period TPS1 according to the decrease in the value of the reference potential VO.
The ink jet printer 1 according to the present embodiment further includes the control unit 2 as the acquirer that acquires the characteristic information relating to the characteristics of the piezoelectric element PZ[m]. The drive signal generating unit 4 as the generator corrects the length of the time period TPS1 as the first time period according to the characteristic information acquired by the control unit 2.
Therefore, the ink jet printer 1 can support a change in the natural vibration period due to the degradation of the piezoelectric element PZ[m] over time.
In the ink jet printer 1 according to the present embodiment, the length of the time period TPS3 as the third time period is equal to or shorter than 0.5×TC.
The potential represented by the waveform PS3 included in the drive signal Com-B rapidly changes from the potential VS1 to the potential VS2, as compared with the change in the potential represented by the waveform PS1 from the reference potential VO to the potential VS1. This suppresses an effect of one vibration occurring in the ejecting section D[m] due to a change in the potential represented by the waveform PS1 to one side on another vibration occurring in the ejecting section D[m] due to a change in the potential represented by the waveform PS3 to the other side. The ink jet printer 1 according to the present embodiment can accurately determine the ejection state of the ejecting section D[m], as compared with the existing techniques.
In the ink jet printer 1 according to the present embodiment, the length of the detection period is equal to or longer than TC.
Therefore, since the detecting circuit 33 detects the residual vibration of the piezoelectric element PZ[m] in the sufficiently long detection period, the ink jet printer 1 according to the present embodiment can accurately determine the ejection state of the ejecting section D[m], as compared with the existing techniques.
In the ink jet printer 1 according to the present embodiment, the drive signal Com-B as the inspection signal includes the waveform PS5 as the third potential-changing element having a potential that changes from the potential VS2 as the third potential to the reference potential VO as the first potential in the time period TPS5 as the fifth time period immediately after the time period TPS4 as the fourth time period. The length of the time period TPS5 is equal to or longer than 0.75×TC.
Therefore, the ink jet printer 1 can suppress an effect of a vibration caused by a change in the potential represented by the waveform PS5 from the potential VS2 to the reference potential VO on the ejecting section D adjacent to the determination target ejecting section DS.
In the ink jet printer 1 according to the present embodiment, the drive signal Com-B as the inspection signal includes the waveform PS5 as the third potential-changing element having a potential that changes from the potential VS2 as the third potential to the reference potential VO as the first potential in the time period TPS5 as the fifth time period immediately after the time period TPS4 as the fourth time period. The length of the time period TPS1 as the first time period is longer than the length of the time period TPS5 as the fifth time period.
Therefore, since the length of the time period TPS1 corresponding to the waveform PS1 is relatively longer than the length of the time period TPS5 corresponding to the waveform PS5, the ink jet printer 1 can accurately determine the ejection state of the ejecting section D[m], as compared with the existing techniques.
In addition, as described above, the method of driving the ink jet printer 1 as the liquid ejecting apparatus according to the present embodiment is a method of driving the ink jet printer 1 having the ejecting section D, the drive signal generating unit 4 as the generator, and the detecting circuit 33 as the vibration detector. The ejecting section D ejects liquid within the cavity 322 as the pressure chamber according to deformation of the piezoelectric element PZ[m]. The drive signal generating unit 4 generates the drive signal Com-B as the inspection signal that deforms the piezoelectric element PZ[m]. The detecting circuit 33 detects a residual vibration occurring in the ejecting section D after the drive signal Com-B is supplied to the piezoelectric element PZ[m]. The drive signal Com-B includes the waveform PS1 as the first potential-changing element having a potential that changes from the reference potential VO as the first potential to the potential VS1 as the second potential in the one direction in the time period TPS1 as the first time period, the waveform PS2 as the first potential-maintaining element having the potential VS1 maintained in the time period TPS2 as the second time period immediately after the time period TPS1, the waveform PS3 as the second potential-changing element having a potential that changes from the potential VS1 to the potential V2 as the third potential in the time period TPS3 as the third time period immediately after the time period TPS2, and the waveform PS4 as the second potential-maintaining element having the potential VS2 maintained in the time period TPS4 as the fourth time period immediately after the time period TPS3. When the natural vibration period of the ejecting section D is TC, the length of the time period TPS1 as the first time period is equal to or longer than 0.75×TC. The detecting circuit 33 as the vibration detector detects the residual vibration in the detection time period included in the time period TPS4 as the fourth time period.
Therefore, the ink jet printer 1 can suppress variance in the characteristics of the residual vibration and improve the accuracy of determining the ejection state of the ejecting section D[m], as compared with a case where the length of the time period TPS1 is shorter than 0.75×TC.
The embodiments described above can be variously modified. Specific aspects of modifications are exemplified as follows. The aspects exemplified below and the aspects described above in the embodiments can be combined as appropriate to the extent that the combined aspects are not mutually inconsistent. In the modifications exemplified below, components that have the same effects and functions as those described in the embodiments are denoted by the same reference signs as those described above, and description of the components are omitted as appropriate.
In the above-described embodiment, as illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-054119 | Mar 2023 | JP | national |
