Patent Application
20230249451
The present application is based on, and claims priority from JP Application Ser. No. 2022-017221, filed Feb. 7, 2022, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a liquid discharge apparatus and a method of driving a liquid discharge head.
A liquid discharge apparatus typified by a piezo-type ink jet printer generally employs a configuration in which a piezoelectric element is disposed on a diaphragm that constitutes a part of a wall surface of a pressure chamber communicating with a nozzle, as disclosed in JP-A-2018-12261, JP-A-2000-260295, and JP-A-2000-25225. Here, liquid such as ink is accommodated in the pressure chamber. By deforming the diaphragm, the piezoelectric element causes the liquid to discharge from the nozzle with expansion or shrinkage of the volume of the pressure chamber.
For example, as disclosed in JP-A-2000-25225, the piezoelectric element of such a liquid discharge apparatus may be divided into an active portion that overlaps a central portion of the pressure chamber and an active portion that overlaps an end portion of the pressure chamber when viewed in the thickness direction of the diaphragm.
However, in the device described in JP-A-2000-25225, the discharge characteristics may change over time due to deterioration of a piezoelectric body, or variations or errors may occur in the discharge characteristics due to manufacturing errors. As a result, there is a problem that good discharge characteristics cannot be stably obtained.
According to an aspect of the present disclosure, there is provided a liquid discharge apparatus including a diaphragm that has a first surface and a second surface facing in a direction opposite to the first surface, a pressure chamber substrate laminated on the first surface and that includes a partition wall partitioning a pressure chamber communicating with a nozzle discharging liquid, a piezoelectric element that includes a first active portion laminated on the second surface and that overlaps a center of the pressure chamber when viewed in a thickness direction of the diaphragm and a second active portion that overlaps the pressure chamber at a position closer to an outer edge of the pressure chamber than the first active portion, and a drive signal generation portion that generates a discharge signal discharging liquid from the nozzle by being supplied to one of the first active portion and the second active portion and a correction signal that is supplied to the other of the first active portion and the second active portion, in which a potential of the discharge signal changes over time and a potential of the correction signal is constant during a discharge period during which the liquid is discharged from the nozzle.
According to another aspect of the present disclosure, there is provided a method of driving a liquid discharge head that includes a diaphragm that has a first surface and a second surface facing in a direction opposite to the first surface, a pressure chamber substrate laminated on the first surface and that includes a partition wall partitioning a pressure chamber communicating with a nozzle discharging liquid, and a piezoelectric element that includes a first active portion laminated on the second surface and that overlaps a center of the pressure chamber when viewed in a thickness direction of the diaphragm and a second active portion that overlaps the pressure chamber at a position closer to an outer edge of the pressure chamber than the first active portion, the method including supplying a discharge signal discharging liquid from the nozzle to one of the first active portion and the second active portion and supplying a correction signal to the other of the first active portion and the second active portion, and changing a potential of the discharge signal over time, and maintaining a potential of the correction signal constant during a discharge period during which the liquid is discharged from the nozzle.
Hereinafter, preferred embodiments according to the present disclosure will be described with reference to the accompanying drawings. In the drawings, the dimensions and scale of each portion are appropriately different from the actual ones, and some parts are schematically illustrated for easy understanding. In addition, the scope of the present disclosure is not limited to these forms unless it is stated in the following description that the present disclosure is particularly limited.
In the following description, for the sake of convenience, the X axis, Y axis, and Z axis that intersect each other are appropriately used. In addition, in the following, one direction along the X axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, the directions opposite to each other along the Y axis are the Y1 direction and the Y2 direction. In addition, the directions opposite to each other along the Z axis are the Z1 direction and the Z2 direction. In addition, viewing in a direction along the Z axis may be referred to as “plan view”.
Here, typically, the Z axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z axis may not be a vertical axis. In addition, the X axis, the Y axis, and the Z axis are typically orthogonal to each other, but are not limited thereto, and may intersect at an angle within a range of, for example, 80° or more and 100° or less.
As illustrated in
The liquid container 10 is a container that stores ink. Examples of specific aspects of the liquid container 10 include a cartridge that can be attached to and detached from the liquid discharge apparatus 100, a bag-shaped ink pack made of a flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 10 is random.
The control unit 20 includes, for example, a processing circuit such as a central processing unit (CPU) or a field programmable gate array (FPGA) and a storage circuit such as a semiconductor memory, and controls the operation of each element of the liquid discharge apparatus 100.
The transport mechanism 30 transports the medium M in the Y2 direction under the control of the control unit 20. The movement mechanism 40 reciprocates the liquid discharge head 50 in the X1 direction and the X2 direction under the control of the control unit 20. In the example illustrated in
Under the control of the control unit 20, the liquid discharge head 50 discharges the ink supplied from the liquid container 10 toward the medium M from each of a plurality of nozzles in the Z2 direction. The discharge is performed in parallel with the transport of the medium M by the transport mechanism 30 and the reciprocating movement of the liquid discharge head 50 by the movement mechanism 40, and thus an image by ink is formed on the surface of the medium M.
As illustrated in
The head chip 51 includes a plurality of discharge portions D for discharging ink. Each of the plurality of discharge portions D includes a piezoelectric element 51f. Here, each piezoelectric element 51f includes an active portion P1 as an example of the “first active portion” and active portions P2 and P3 as examples of “second active portions”. The active portion P1 is driven by receiving the supply of a supply signal Vin-A. On the other hand, each of the active portions P2 and P3 is driven by receiving the supply of a supply signal Vin-B. Although not illustrated in
Under the control of the control unit 20, the switching circuit 52 switches whether or not to supply a discharge signal Com output from the control unit 20 to the active portion P1 as the supply signal Vin-A to each of the plurality of piezoelectric elements 51f of the head chip 51. In the present embodiment, the switching circuit 52 supplies a correction signal DC as the supply signal Vin-B to the active portions P2 and P3 of each piezoelectric element 51f. The details of the switching circuit 52 will be described later with reference to
In the example illustrated in
As illustrated in
The control circuit 21 has a function of controlling the operation of each portion of the liquid discharge apparatus 100 and a function of processing various data. The control circuit 21 includes, for example, one or more processors such as a central processing unit (CPU).
The storage circuit 22 stores various programs executed by the control circuit 21 and various data such as print data Img processed by the control circuit 21. The storage circuit 22 includes, for example, a semiconductor memory of one or both of volatile memories such as a random access memory (RAM) and a non-volatile memory such as a read only memory (ROM), an electrically erasable programmable read-only memory (EEPROM) or a programmable ROM (PROM). The print data Img is supplied from an external device 200 such as a personal computer or a digital camera.
The power supply circuit 23 receives power from a commercial power supply (not illustrated) and generates various predetermined potentials. The various generated potentials are appropriately supplied to each portion of the liquid discharge apparatus 100. For example, the power supply circuit 23 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid discharge head 50. In addition, the power supply potential VHV is supplied to the drive signal generation circuit 24.
The drive signal generation circuit 24 is a circuit that generates a discharge signal Com and a correction signal DC. Specifically, the drive signal generation circuit 24 includes, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation circuit 24, the DA conversion circuit converts a waveform designation signal dCom from the control circuit 21 from a digital signal to an analog signal, and the amplifier circuit generates a discharge signal Com by amplifying the analog signal using the power supply potential VHV from the power supply circuit 23. In addition, in the drive signal generation circuit 24, the DA conversion circuit converts a voltage designation signal dDC described later from the control circuit 21 from a digital signal to an analog signal, and the amplifier circuit generates a correction signal DC by amplifying the analog signal using the power supply potential VHV from the power supply circuit 23. Here, among the waveforms included in the discharge signal Com, the waveform signal actually supplied to the active portion P1 of the piezoelectric element 51f is the supply signal Vin-A described above. The correction signal DC is supplied as the supply signal Vin-B described above to the active portion P2 or the active portion P3 of the piezoelectric element 51f. The waveform designation signal dCom is a digital signal for defining the waveform of the discharge signal Com. The voltage designation signal dDC is a digital signal for defining the voltage value of the correction signal DC.
The control circuit 21 controls the operation of each portion of the liquid discharge apparatus 100 by executing a program stored in the storage circuit 22. Here, by executing the program, the control circuit 21 generates control signals Sk1 and Sk2, a print data signal SI, a waveform designation signal dCom, a voltage designation signal dDC, a latch signal LAT, a change signal CNG, and a clock signal CLK as a signal for controlling the operation of each portion of the liquid discharge apparatus 100.
The control signal Sk1 is a signal for controlling the drive of the transport mechanism 30. The control signal Sk2 is a signal for controlling the drive of the movement mechanism 40. The print data signal SI is a digital signal for designating an operating state of the piezoelectric element 51f. The latch signal LAT and the change signal CNG are timing signals that are used together with the print data signal SI and define the ink discharge timing from each nozzle of the head chip 51. These timing signals are generated, for example, based on the output of an encoder that detects the position of the carriage 41 described above.
In addition, the control circuit 21 adjusts the voltage value indicated by the voltage designation signal dDC according to the print data signal SI. As a result, the correction signal DC is adjusted. As a result, the size of the ink droplet discharged from the nozzle N is adjusted for each unit period Tu described later. Here, the print data signal SI is an example of “droplet amount information”, and is information on the amount of ink discharged from the nozzle N per one discharge.
Furthermore, during the printing period during which the liquid discharge head 50 continuously discharges ink, the control circuit 21 controls driving of the drive signal generation circuit 24 so as to generate the correction signal DC. During a period other than the printing period, such as a standby period, the control circuit 21 lowers the potential of the correction signal DC or stops generation of the correction signal DC by the drive signal generation circuit 24. As a result, the potential of the correction signal DC decreases, or the correction signal DC is supplied to neither the active portions P1, P2, nor P3 during periods other than a discharge period T described later.
Here, the pressure chamber substrate 51b, the diaphragm 51e, the plurality of piezoelectric elements 51f, the case 51h, and the cover 51g are installed in a region located in the Z1 direction from the flow path substrate 51a. On the other hand, the nozzle plate 51c and the vibration absorber 51d are installed in a region located in the Z2 direction from the flow path substrate 51a. Each element of the liquid discharge head 50 is generally a plate-like member elongated in the direction along the Y axis, and is bonded to each other with an adhesive, for example.
As illustrated in
The flow path substrate 51a is a plate-like member for forming a flow path for ink. As illustrated in
The pressure chamber substrate 51b is a plate-like member in which a plurality of pressure chambers C corresponding to the plurality of nozzles N are formed. The pressure chamber C is located between the flow path substrate 51a and the diaphragm 51e, and is a space called a cavity for applying pressure to the ink filled in the pressure chamber C. The plurality of pressure chambers C are arranged in the direction along the Y axis. Each pressure chamber C is configured to include holes that open on both surfaces of the pressure chamber substrate 51b, and has an elongated shape extending in the direction along the X axis. The end of each pressure chamber C in the X2 direction communicates with the corresponding supply flow path Ra. On the other hand, the end of each pressure chamber C in the X1 direction communicates with the corresponding communication flow path Na. The cross-sectional area of the supply flow path Ra is narrower than that of the pressure chamber C, and this portion functions as a flow path resistance, so that backflow is suppressed when pressure is applied to the ink. The pressure chamber substrate 51b is manufactured by processing a silicon single crystal substrate by, for example, semiconductor manufacturing technique, similar to the nozzle plate 51c described above. However, other known methods and materials may be appropriately used for the manufacture of each of the pressure chamber substrates 51b.
The diaphragm 51e is disposed on the surface of the pressure chamber substrate 51b facing the Z1 direction. The diaphragm 51e is a plate-like member that can elastically deform. In the example illustrated in
The plurality of piezoelectric elements 51f corresponding to the nozzles N or the pressure chambers C different from each other are disposed on the surface of the diaphragm 51e facing the Z1 direction. Each piezoelectric element 51f is a passive element deformed by the supply of the discharge signal Com and the correction signal DC, and has an elongated shape extending in the direction along the X axis. The plurality of piezoelectric elements 51f are arranged in a direction along the Y axis so as to correspond to the plurality of pressure chambers C. When the diaphragm 51e vibrates in conjunction with the deformation of the piezoelectric element 51f, the pressure in the pressure chamber C fluctuates, so that ink is discharged from the nozzle N. Details of the piezoelectric element 51f will be described with reference to
The case 51h is a case for storing the ink supplied to the plurality of pressure chambers C, and is bonded to the surface of the flow path substrate 51a facing the Z1 direction with an adhesive or the like. The case 51h is made of, for example, a resin material and manufactured by injection molding. The case 51h is provided with an accommodation portion R2 and an inlet IH. The accommodation portion R2 is a recessed portion having an outer shape corresponding to the opening portion R1 of the flow path substrate 51a. The inlet IH is a through-hole that communicates with the accommodation portion R2. A space defined by the opening portion R1 and the accommodation portion R2 functions as a liquid storage chamber R, which is a reservoir for storing ink. Ink from the liquid container 10 is supplied to the liquid storage chamber R through the inlet IH.
The vibration absorber 51d is an element for absorbing pressure fluctuations in the liquid storage chamber R. The vibration absorber 51d is, for example, a compliance substrate that is an elastically deformable flexible sheet member. Here, the vibration absorber 51d is disposed on the surface of the flow path substrate 51a facing the Z2 direction so as to block the opening portion R1 of the flow path substrate 51a and the plurality of supply flow paths Ra to constitute the bottom surface of the liquid storage chamber R.
The cover 51g is a structure that protects the plurality of piezoelectric elements 51f and reinforces the mechanical strength of the pressure chamber substrate 51b and the diaphragm 51e. The cover 51g is bonded to the surface of the diaphragm 51e with an adhesive, for example. The cover 51g is provided with recessed portions that accommodate the plurality of piezoelectric elements 51f.
The wiring substrate 51i is bonded to the surface of the pressure chamber substrate 51b or the diaphragm 51e facing the Z1 direction. The wiring substrate 51i is a mounting component on which a plurality of wirings for electrically coupling the control unit 20 and the liquid discharge head 50 are formed. The wiring substrate 51i is a flexible wiring substrate such as a flexible printed circuit (FPC) and a flexible flat cable (FFC). The switching circuit 52 is mounted on the wiring substrate 51i.
In the example illustrated in
As illustrated in
The diaphragm 51e includes the first layer 51e1 and the second layer 51e2, which are laminated in this order in the Z1 direction. The first layer 51e1 is, for example, an elastic film made of silicon oxide (SiO2). The second layer 51e2 is, for example, an insulating film made of zirconium oxide (ZrO2).
The first layer 51e1 is not limited to silicon oxide. In addition, a part or all of the diaphragm 51e may be integrally made of the same material as that of the pressure chamber substrate 51b. In addition, the diaphragm 51e may be made of a layer of single material.
As illustrated in
Another layer such as a layer for enhancing adhesion may be appropriately interposed between the layers of the piezoelectric element 51f or between the piezoelectric element 51f and the diaphragm 51e. In addition, a seed layer that improves the orientation of the piezoelectric layer 51f2 may be provided between the first electrode layer 51f1 and the piezoelectric layer 51f2.
The first electrode layer 51f1 includes individual electrodes 51f1a, 51f1b, and 51f1c for each piezoelectric element 51f. Each of the individual electrodes 51f1a, 51f1b, and 51f1c extends in the direction along the X axis. The individual electrodes 51f1a, 51f1b, and 51f1c are arranged in the direction along the Y axis at intervals from each other.
Here, the individual electrode 51f1a is disposed in the central portion of the pressure chamber C in the width direction and overlaps the center of the pressure chamber C in plan view. The discharge signal Com is supplied to the individual electrode 51f1a through the wiring. On the other hand, each of the individual electrode 51f1b and the individual electrode 51f1c is disposed at an end portion of the pressure chamber C in the width direction, and overlaps the pressure chamber C at a position closer to the outer edge BD of the pressure chamber C than the individual electrode 51f1a in plan view. The correction signal DC is supplied to each of the individual electrodes 51f1b and 51f1c through the wiring.
The first electrode layer 51f1 includes, for example, a first layer made of titanium (Ti), a second layer made of platinum (Pt), and a third layer made of iridium (Ir), which are laminated in this order in the Z1 direction.
Here, the first layer described above of the first electrode layer 51f1 functions as an adhesion layer that improves adhesion of the first electrode layer 51f1 to the diaphragm 51e. Although the thickness of the first layer is not particularly limited, the thickness is, for example, approximately 3 nm or more and 50 nm or less. The constituent material of the first layer is not limited to titanium, and for example, chromium may be used instead of titanium.
In addition, platinum forming the second layer described above and iridium forming the third layer of the first electrode layer 51f1 are both electrode materials with excellent conductivity and have chemical properties close to each other. Therefore, the characteristics of the first electrode layer 51f1 as an electrode can be improved. Although the thickness of the second layer is not particularly limited, the thickness is, for example, approximately 50 nm or more and 200 nm or less. Although the thickness of the third layer is not particularly limited, the thickness is, for example, approximately 4 nm or more and 20 nm or less.
The configuration of the first electrode layer 51f1 is not limited to the example described above. For example, either the second layer or the third layer described above may be omitted, or a layer made of iridium may be further provided between the first layer and the second layer described above. In addition, a layer made of an electrode material other than iridium and platinum may be used instead of the second layer and third layer or in addition to the second layer and third layer. Examples of the electrode material include metal materials such as aluminum (Al), nickel (Ni), gold (Au), and copper (Cu).
The piezoelectric layer 51f2 is disposed between the first electrode layer 51f1 and the second electrode layer 51f3. The piezoelectric layer 51f2 has a strip shape extending in the direction along the Y axis so as to be continuous over the plurality of piezoelectric elements 51f. The piezoelectric layer 51f2 may be provided individually for each piezoelectric element 51f or for each active portion P1, P2, and P3.
The piezoelectric layer 51f2 is made of a piezoelectric material having a perovskite crystal structure represented by the general composition formula ABO3. Examples of the piezoelectric material include known materials such as lead titanate (PbTiO3) and lead zirconate titanate (Pb(Zr,Ti)O3). In addition, the piezoelectric material forming the piezoelectric layer 51f2 may be a non-lead material such as barium titanate.
For example, the piezoelectric layer 51f2 is formed by forming a piezoelectric precursor layer by a liquid phase method such as a sol-gel method or a metal organic decomposition (MOD) method, and then firing and crystallizing the precursor layer. Here, the piezoelectric layer 51f2 may be configured to include a single layer, but when being configured to include a plurality of layers, even in a case in which the thickness of the piezoelectric layer 51f2 is increased, there is an advantage that the characteristics of the piezoelectric layer 51f2 are likely to be improved.
The second electrode layer 51f3 is a strip-shaped common electrode that extends in the direction along the Y axis so as to be continuous over the plurality of piezoelectric elements 51f. The offset potential VBS is supplied as a predetermined reference voltage to the second electrode layer 51f3.
The second electrode layer 51f3 includes, for example, a layer made of iridium (Ir) and a layer made of titanium (Ti), which are laminated in this order in the Z1 direction.
The constituent material of the second electrode layer 51f3 is not limited to iridium and titanium, and may be, for example, metal materials such as platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu).
The above piezoelectric element 51f includes the active portions P1, P2, and P3. The active portion P1 is a portion of the piezoelectric element 51f where the individual electrode 51f1a, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e. The active portion P2 is a portion of the piezoelectric element 51f where the individual electrode 51f1b, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e. The active portion P3 is a portion of the piezoelectric element 51f where the individual electrode 51f1c, the piezoelectric layer 51f2, and the second electrode layer 51f3 all overlap when viewed in the thickness direction of the diaphragm 51e.
The active portion P1 is disposed between the active portion P2 and the active portion P3. In the example illustrated in
Here, the active portion P1 overlaps the center of the pressure chamber C and does not overlap the outer edge BD of the pressure chamber C when viewed in the thickness direction of the diaphragm 51e. On the other hand, each of the active portion P2 and the active portion P3 overlaps the pressure chamber C at a position closer to the outer edge BD of the pressure chamber C than the active portion P1 when viewed in the thickness direction of the diaphragm 51e. In the example illustrated in
A width W1 of the active portion P1 along the Y axis is smaller than a width of the pressure chamber C along the Y axis. Preferably, the width W1 is smaller than the width of the pressure chamber C along the Y axis and is ½ or more of the width of the pressure chamber C along the Y axis. In addition, the width W2 of the active portion P2 along the Y axis is smaller than the width of the pressure chamber C along the Y axis, and preferably ½ or less of the width of the pressure chamber C along the Y axis. Similarly, the width W3 of the active portion P3 along the Y axis is smaller than the width of the pressure chamber C along the Y axis, and preferably ½ or less of the width of the pressure chamber C along the Y axis. Here, the width W2 and width W3 may be equal to or different from each other.
As illustrated in
In the present embodiment, the wiring LHb is electrically coupled to the individual electrodes 51f1b and 51f1c of the first electrode layer 51f1 of the piezoelectric element 51f. In the example illustrated in
The switching circuit 52 includes a plurality of switches SWa corresponding one-to-one with the plurality of piezoelectric elements 51f, and a coupling state designation circuit 52a that designates the coupling state of these switches.
The switch SWa is a switch that switches between conduction (on) and non-conduction (off) between the wiring LHa for transmitting the discharge signal Com and the individual electrode 51f1a of the piezoelectric element 51f. Each of these switches is, for example, a transmission gate.
The coupling state designation circuit 52a generates a coupling state designation signal SLa designating on/off of the plurality of switches SWa based on the clock signal CLK, the print data signal SI, the latch signal LAT, and the change signal CNG supplied from the control circuit 21.
For example, although not illustrated, the coupling state designation circuit 52a includes a plurality of transfer circuits, a plurality of latch circuits, and a plurality of decoders so as to correspond one-to-one with the plurality of piezoelectric elements 51f. Among these circuits, the print data signal SI is supplied to the transfer circuit. Here, the print data signal SI includes an individual designation signal for each piezoelectric element 51f, and the individual designation signal is serially supplied to the print data signal SI. For example, the individual designation signal is sequentially transferred to the plurality of transfer circuits in synchronization with the clock signal CLK. In addition, the latch circuit latches the individual designation signal supplied to the transfer circuit based on the latch signal LAT. In addition, the decoder also generates a coupling state designation signal SLa based on the individual designation signal, the latch signal LAT, and the change signal CNG.
On/off of the switch SWa is switched according to the coupling state designation signal SLa generated as described above. For example, the switch SWa is turned on when the coupling state designation signal SLa is at high level, and turned off when the coupling state designation signal SLa is at low level. As described above, the switching circuit 52 supplies a part or all of the waveform included in the discharge signal Com as the supply signal Vin-A, and the correction signal DC as the supply signal Vin-B to the one or more piezoelectric elements 51f selected from the plurality of piezoelectric elements 51f.
The discharge signal Com is a signal that discharges the liquid from the nozzle N by being supplied to the active portion P1. As illustrated in
In the example illustrated in
Here, the waveform portion of the discharge signal Com that lowers the potential from the intermediate potential Vc to the potential VL is the expansion element EEa1 that expands the volume of the pressure chamber C. The waveform portion of the discharge signal Com that maintains the potential at the potential VL is the holding element ERa1. The waveform portion of the discharge signal Com that raises the potential from the potential VL to the potential VH is the shrinkage element ESa that shrinks the volume of the pressure chamber C. The waveform portion of the discharge signal Com that maintains the potential at the potential VH is the holding element ERa2. The waveform portion of the discharge signal Com that lowers the potential from the potential VH to the intermediate potential Vc is the expansion element EEa2 that expands the volume of the pressure chamber C.
The waveform of the discharge signal Com is not limited to the example illustrated in
On the other hand, the correction signal DC is a constant potential signal of potential VH1. The potential VH1 is preferably higher than the intermediate potential Vc, but may be lower than the intermediate potential Vc. In the example illustrated in
When the holding element ERa1 of the discharge signal Com is supplied to the active portion P1, the diaphragm 51e deforms so that the first surface F1 is recessed as illustrated in
The actual natural state of the diaphragm 51e may not be the state indicated by the two-dot chain lines in
As illustrated in
Therefore, the correction signal DC is used. When receiving the supply of the correction signal DC, the active portions P2 and P3 deform the diaphragm 51e in the direction opposite to when the active portion P1 receives the supply of the discharge signal Com. This is because the displacement of the end closer to the partition wall 511 is restricted by the partition wall 511, whereas the displacement of the end farther from the partition wall 511 is unlikely to be subject to such restriction, among both ends of the active portions P2 and P3 in the direction along the Y axis. Here, the correction signal DC drives the piezoelectric element 51f so that the diaphragm 51e is in an ideal natural state in a state where the discharge signal Com is not supplied to the piezoelectric element 51f. As a result, the driving efficiency of the piezoelectric element 51f can be enhanced. In addition, it is also possible to reduce variations in discharge characteristics when comparing the discharge characteristics in each of the discharge portions D.
As described above, the liquid discharge apparatus 100 is provided with the diaphragm 51e, the pressure chamber substrate 51b, the piezoelectric element 51f, and the drive signal generation circuit 24 which is an example of the “drive signal generation portion”. The diaphragm 51e has a first surface F1 and a second surface F2 facing in the opposite direction to the first surface F1. The pressure chamber substrate 51b includes a partition wall 51b1 that is laminated on the first surface F1 and partitions the pressure chambers C communicating with the nozzles N discharging ink as an example of “liquid”. The piezoelectric element 51f is laminated on the second surface F2 and includes the active portion P1 overlapping the center of the pressure chamber C when viewed in the thickness direction of the diaphragm 51e, and the active portions P2 and P3 overlapping the pressure chamber C at positions closer to the outer edge BD of the pressure chamber C than the active portion P1. The drive signal generation circuit 24 generates the discharge signal Com and the correction signal DC.
The discharge signal Com causes ink to be discharged from the nozzle N by being supplied to one of the active portion P1 and the active portions P2 and P3. The correction signal DC is supplied to the other of the active portion P1 and the active portions P2, P3. Here, during the discharge period T during which ink is discharged from the nozzles N, the potential of the discharge signal Com changes over time, and the potential of the correction signal DC is constant.
In the liquid discharge apparatus 100 described above, during the discharge period T, the tension of the diaphragm 51e can be appropriately adjusted by supplying the correction signal DC of a constant potential to the other of the active portion P1 and the active portions P2 and P3. Therefore, it is possible to reduce the influence of deterioration of the piezoelectric element 51f, manufacturing variations among the discharge portions D, and the like, on the discharge characteristics of the ink from the nozzles N. As a result, good discharge characteristics can be stably obtained. In addition, by employing a driving method using the discharge signal Com and the correction signal as described above as a method of driving the liquid discharge head 50, good discharge characteristics can be stably obtained.
In the present embodiment, as described above, the discharge signal Com is supplied to the active portion P1. On the other hand, the correction signal DC is supplied to the active portions P2 and P3. As a result, a stress acts so that the diaphragm 51e is displaced in the direction where each of the second surfaces F2 is recessed, that is, in the direction where the second surface F2 is projected as a whole, in the active portions P2 and P3, and the deflection of the diaphragm 51e in the direction where the first surface F1 is projected due to manufacturing errors or the like is alleviated. As a result, the driving efficiency of the piezoelectric element 51f can be suppressed from decreasing, and the influence of manufacturing variations among the discharge portions D can be reduced. In addition, since the active portions P2 and P3 are located at both ends of the pressure chamber C in the direction along the Y axis, the overall tension of the diaphragm 51e can be finely adjusted compared to the configuration in which the correction signal DC is supplied to the active portion P1. As a result, the reliability of the diaphragm 51e can be improved.
In addition, as described above, the liquid discharge apparatus 100 is provided with the discharge portion D_1 as an example of the “first discharge portion” and the discharge portion D_2 as an example of the “second discharge portion”. Each of the discharge portion D_1 and the discharge portion D_2 includes the nozzle N, the pressure chamber C, the active portion P1, and the active portions P2 and P3. The potential of the correction signal DC used for the discharge portion D_1 is equal to the potential of the correction signal DC used for the discharge portion D_2. Therefore, the circuit configuration of the drive signal generation circuit 24 can be simplified compared to the configuration in which the correction signal DC is generated individually for each discharge portion D.
Furthermore, as described above, the amount of deflection of the diaphragm 51e in the state where the correction signal DC is supplied to one of the active portion P1 and the active portions P2 and P3 is smaller than the amount of deflection of the diaphragm 51e in a state where the correction signal DC is supplied to neither the active portion P1 nor the active portions P2 and P3. Therefore, the initial deflection of the diaphragm 51e can be reduced. As a result, the amount of deflection of the diaphragm 51e when ink is discharged from the nozzles N can be increased.
In addition, as described above, the liquid discharge apparatus 100 is further provided with the control circuit 21, which is an example of the “control portion”. The control circuit 21 controls driving of the drive signal generation circuit 24. Here, by adjusting the correction signal DC by the control circuit 21, it is possible to optimize the discharge characteristics or improve the discharge characteristics.
Here, as described above, the control circuit 21 adjusts the correction signal DC based on the print data signal SI, which is an example of “droplet amount information”. The print data signal SI is information on the amount of ink discharged from the nozzles N per one discharge. Therefore, ink droplets having different sizes from each other can be discharged from the nozzles N using a single waveform of the discharge signal Com.
In addition, as described above, during periods other than the discharge period T, power saving of the liquid discharge apparatus 100 can be achieved by lowering the potential of the correction signal DC or supplying the correction signal DC to neither the active portion P1 nor the active portions P2 and P3.
Hereinafter, a second embodiment of the present disclosure will be described. Hereinafter, the description will focus on differences from the first embodiment.
The control unit 20A is configured in the same manner as the control unit 20 described above, except that a deterioration information generation circuit 25 is added and the correction signal DC is adjusted accordingly. The deterioration information generation circuit 25 generates deterioration information DD. The deterioration information DD is information on deterioration of at least one of the nozzle plate 51c having the nozzle N, the pressure chamber substrate 51b, the diaphragm 51e, and the piezoelectric element 51f. Here, examples of deterioration include adhesion of foreign matter in the vicinity of the nozzle, increase in ink viscosity, entry of air bubbles into the pressure chamber, fatigue of the piezoelectric element and diaphragm, and the like.
The deterioration information generation circuit 25 measures the number of times the piezoelectric element 51f is driven or the period of use based on the print data signal SI and the like from the control circuit 21, and generates deterioration information DD based on the measurement result. In addition, in the present embodiment, the deterioration information generation circuit 25 generates the deterioration information DD based on the residual vibration signal NVT from the liquid discharge head 50A.
In the present embodiment, the control circuit 21 controls driving of the drive signal generation circuit 24 so as to adjust the correction signal DC based on the deterioration information DD. Specifically, the control circuit 21 adjusts the correction signal DC so that the higher the degree of deterioration indicated by the deterioration information DD, the higher the potential.
In addition, in the present embodiment, the control circuit 21 can execute a detection operation using a detection circuit 53 described later. This detection operation is performed by driving the active portion P1 of the piezoelectric element 51f by the discharge signal Com and detecting the output signal Vout due to the electromotive force of the active portions P2 and P3 of the piezoelectric element 51f, which is the residual vibration accompanying this driving by the detection circuit 53. Here, the waveform of the discharge signal Com is an example of the “detection waveform”. The execution timing and the like of this detection operation are appropriately determined according to a program set in advance or an operation from the user. In addition, the discharge signal Com may include a detection waveform separately from the waveform described above.
The liquid discharge head 50A is configured in the same manner as the liquid discharge head 50 described above, except that a switching circuit 52A is provided instead of the switching circuit 52 and a detection circuit 53 is added.
The detection circuit 53 generates a residual vibration signal NVT based on the output signal Vout generated by the piezoelectric element 51f. For example, the detection circuit 53 generates the residual vibration signal NVT by amplifying the output signal Vout after removing noise. The residual vibration signal NVT indicates residual vibration, which is vibration remaining in the ink flow path in the head chip 51 after the piezoelectric element 51f is driven.
As illustrated in
The switching circuit 52A includes a plurality of switches SWa and a plurality of switches SWs corresponding one-to-one with the plurality of piezoelectric elements 51f, and a coupling state designation circuit 52b that designates the coupling state of these switches.
The switch SWs is a switch that switches between conduction (on) and non-conduction (off) between the wiring LHs for transmitting the output signal Vout and the individual electrodes 51f1b and 51f1c of the piezoelectric element 51f. Each of these switches is, for example, a transmission gate.
The coupling state designation circuit 52b generates a coupling state designation signal SLa designating on/off of the plurality of switches SWa, and a coupling state designation signal SLs designating on/off of the plurality of switches SWs, based on the clock signal CLK, the print data signal SI, the latch signal LAT, and the change signal CNG supplied from the control circuit 21.
On/off of the switch SWa is switched according to the coupling state designation signal SLa generated as described above. In addition, on/off of the switch SWs is switched according to the coupling state designation signal SLs. As described above, the switching circuit 52A supplies the output signal Vout from one or more piezoelectric elements 51f selected from the plurality of piezoelectric elements 51f to the detection circuit 46.
According to the second embodiment described above, it is possible to stably obtain good discharge characteristics. In the present embodiment, as described above, the control circuit 21 adjusts the correction signal DC based on the deterioration information DD. The deterioration information DD is information on deterioration of at least one of the nozzle plate 51c having the nozzle N, the pressure chamber substrate 51b, the diaphragm 51e, and the piezoelectric element 51f. Therefore, it is possible to reduce fluctuations in discharge characteristics due to deterioration of at least one of the nozzle plate 51c having the nozzles N, the pressure chamber substrate 51b, the diaphragm 51e, and the piezoelectric element 51f.
In addition, the liquid discharge apparatus 100A is further provided with the detection circuit 53 as described above. The drive signal generation circuit 24 generates a discharge signal Com as an inspection signal to be supplied to one of the active portion P1 and the active portions P2 and P3. The detection circuit 53 detects, as an output signal Vout, an electromotive force generated in the other of the active portion P1 and the active portions P2 and P3 by supplying the discharge signal Com to one of the active portion P1 and the active portions P2 and P3. Therefore, it is possible to improve the inspection accuracy and shorten the inspection time as compared to a configuration in which one active portion performs both the driving by the inspection signal and the output of the electromotive force resulting from the driving.
Hereinafter, a third embodiment of the present disclosure will be described. Hereinafter, the description will focus on differences from the first embodiment.
The control unit 20B is configured in the same manner as the control unit 20A described above, except that a viscosity information generation circuit 26 is provided in place of the deterioration information generation circuit 25 and a method of adjusting the correction signal DC is different accordingly. A viscosity information generation circuit 26 generates viscosity information DV. The viscosity information DV is information on the viscosity of the ink discharged from the nozzles N.
The viscosity information generation circuit 26 generates viscosity information DV based on the residual vibration signal NVT from the liquid discharge head 50A.
In the present embodiment, the control circuit 21 controls driving of the drive signal generation circuit 24 so as to adjust the correction signal DC based on the viscosity information DV. Specifically, the control circuit 21 adjusts the correction signal DC so that the higher the viscosity indicated by the viscosity information DV, the higher the potential.
According to the third embodiment described above, it is possible to stably obtain good discharge characteristics. In the present embodiment, as described above, the control circuit 21 adjusts the correction signal DC based on the viscosity information DV on the viscosity of the ink discharged from the nozzles N. Therefore, it is possible to reduce fluctuations in discharge characteristics due to changes in the viscosity of the ink discharged from the nozzles N.
Hereinafter, a fourth embodiment of the present disclosure will be described. Hereinafter, the description will focus on differences from the first embodiment.
The control unit 20C is configured in the same manner as the control unit 20 described above, except that a temperature information generation circuit 27 is added and the correction signal DC is adjusted accordingly. The temperature information generation circuit 27 generates temperature information DT. The temperature information DT is information on the temperature of the ink discharged from the nozzles N.
The temperature information generation circuit 27 generates temperature information DT based on the output from a temperature sensor 54 described later.
In the present embodiment, the control circuit 21 controls driving of the drive signal generation circuit 24 so as to adjust the correction signal DC based on the temperature information DT. Specifically, the control circuit 21 adjusts the correction signal DC so that the lower the temperature indicated by the temperature information DT, the higher the potential.
The liquid discharge head 50C is configured in the same manner as the liquid discharge head 50 described above, except that the temperature sensor 54 is added. The temperature sensor 54 is an element such as a thermistor that detects the temperature of the ink discharged from the nozzles N. For example, the temperature sensor 54 is installed inside the head chip 51.
According to the fourth embodiment described above, it is possible to stably obtain good discharge characteristics. In the present embodiment, as described above, the control circuit 21 adjusts the correction signal DC based on the temperature information DT on the temperature of the ink discharged from the nozzles N. Therefore, it is possible to reduce fluctuations in discharge characteristics due to changes in the temperature of the ink discharged from the nozzles N.
Hereinafter, a fifth embodiment of the present disclosure will be described. Hereinafter, the description will focus on differences from the first embodiment.
According to the fifth embodiment described above, it is possible to stably obtain good discharge characteristics. In the present embodiment, as described above, the discharge signal Com is supplied to the active portions P2 and P3, and the correction signal DC is supplied to the active portion Pl. Therefore, the displacement amount of the diaphragm 51e can be easily increased compared to the configuration in which the discharge signal Com is supplied to the active portion P1. As a result, the discharge efficiency of the ink from the nozzles N can be improved.
Hereinafter, a sixth embodiment of the present disclosure will be described. Hereinafter, the description will focus on differences from the first embodiment.
The control unit 20E is configured in the same manner as the control unit 20 described above, except that a drive signal generation circuit 24E is provided instead of the drive signal generation circuit 24. The drive signal generation circuit 24E is an example of a “drive signal generation portion” and generates a correction signal DC1 and a correction signal DC2 based on the voltage designation signal dDC. Each of the correction signal DC1 and the correction signal DC2 is a constant potential signal. However, the potentials of the correction signal DC1 and the correction signal DC2 are different from each other. In the present embodiment, the control circuit 21 generates a signal for selecting either the correction signal DC1 or the correction signal DC2. This signal may be generated independently or may be included in the print data signal SI or the like.
The liquid discharge head 50E is configured in the same manner as the liquid discharge head 50 described above, except that a switching circuit 52E is provided instead of the switching circuit 52. Under the control of the control unit 20E, the switching circuit 52E switches whether or not to supply a discharge signal Com output from the control unit 20E to the active portion P1 as the supply signal Vin-A to each of the plurality of piezoelectric elements 51f. In addition, the switching circuit 52E selects one of the correction signal DC1 and the correction signal DC2 based on the print data signal SI or the like, and supplies the correction signal as the supply signal Vin-B to the active portions P2 and P3 of the piezoelectric elements 51f.
This selection is not particularly limited and may be random, but is determined according to, for example, variations in the discharge characteristics of the plurality of discharge portions D. In addition, this selection may be made based on the deterioration information DD, the viscosity information DV, or the temperature information DT described above.
As illustrated in
The switching circuit 52E includes a plurality of switches SWa, a plurality of switches SWb, and a plurality of switches SWc corresponding one-to-one with the plurality of piezoelectric elements 51f, and a coupling state designation circuit 52c that designates the coupling state of these switches.
The switch SWb is a switch that switches between conduction (on) and non-conduction (off) between the wiring LHb1 and the individual electrodes 51f1b and 51f1c of the piezoelectric element 51f. The switch SWc is a switch that switches between conduction (ON) and non-conduction (OFF) between the wiring LHb2 and the individual electrodes 51f1b and 51f1c of the piezoelectric element 51f. Each of these switches is, for example, a transmission gate.
The coupling state designation circuit 52c generates a coupling state designation signal SLa designating on/off of the plurality of switches SWa, a coupling state designation signal SLb designating on/off of the plurality of switches SWb, and a coupling state designation signal SLc designating on/off of the plurality of switches SWc, based on the signal from the control circuit 21. Here, in the same discharge portion D, when one of the switch SWb and the switch SWc is on, the other is off.
On/off of the switch SWa is switched according to the coupling state designation signal SLa generated as described above. On/off of the switch SWb is switched according to the coupling state designation signal SLb.
On/off of the switch SWc is switched according to the coupling state designation signal SLc. As described above, the switching circuit 52E can change the potentials of the individual electrodes 51f1b and 51f1c. In addition, it is also possible to use the correction signal DC1 for one of the discharge portions D_1 and D_2 and the correction signal DC2 for the other.
According to the sixth embodiment described above, it is possible to stably obtain good discharge characteristics. In the present embodiment, as described above, the liquid discharge apparatus 100E is provided with a plurality of discharge portions D that discharge ink. Each of the plurality of discharge portions D includes the nozzle N, the pressure chamber C, the active portion P1, and the active portions P2 and P3. It is also possible to use the correction signal DC1 for one of the discharge portions D_1 and D_2 and the correction signal DC2 for the other. Here, the potential of the correction signal DC1 is different from the potential of the correction signal DC2. Therefore, the tension of the diaphragm 51e can be adjusted individually for each discharge portion D.
Each embodiment in the above illustration can be variously modified. Specific modification aspects that can be applied to each of the above-described embodiments are exemplified below. Two or more aspects randomly selected from the following examples can be appropriately merged to the extent that these aspects do not contradict each other.
Although the configuration in which the piezoelectric layer is interposed between the individual electrodes and the common electrode is exemplified in the above embodiment, the present disclosure is not limited thereto, and a configuration in which a piezoelectric layer is interposed between the individual electrodes may be used. In addition, the first electrode layer 51f1 may be used as a common electrode, and the second electrode layer 52f3 may be used as an individual electrode.
Although the serial-type liquid discharge apparatus 100 in which the carriage 41 on which the liquid discharge head 50 is mounted is reciprocated is exemplified in each of the above-described embodiments, the present disclosure can also be applied to a line-type liquid discharge apparatus in which a plurality of nozzles N are distributed over the entire width of the medium M.
The liquid discharge apparatus 100 exemplified in each of the above-described embodiments can be employed in various types of equipment such as facsimile machines and copiers, in addition to equipment dedicated to printing. However, the application of the liquid discharge apparatus of the present disclosure is not limited to printing. For example, a liquid discharge apparatus that discharges a solution of a coloring material is used as a manufacturing apparatus for forming a color filter of a liquid crystal display device. In addition, a liquid discharge apparatus for discharging a solution of a conductive material is used as a manufacturing apparatus for forming wiring and electrodes on a wiring substrate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-017221 | Feb 2022 | JP | national |
