Printing device

Abstract

To provide a printing device capable of suppressing an increase in power consumption.SOLUTION: There is provided a printing device according to one embodiment of the present disclosure. An energy applying element includes a piezoelectric body in which a plurality of piezoelectric layers are stacked in a stacking direction, and which has a first electrode formed on a first surface extending in an orthogonal direction orthogonal to the stacking direction, a second electrode formed on a second surface extending in the orthogonal direction and provided at a position different from the first surface in the stacking direction, and a third electrode formed on a third surface extending in the orthogonal direction and provided at a position different from the first surface and the second surface in the stacking direction. The piezoelectric body includes: a first active portion interposed between the first electrode and the second electrode in the stacking direction; and a second active portion interposed between the second electrode and the third electrode in the stacking direction. A voltage application circuit includes a first charging body connected to the first electrode or a second charging body connected to the second electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present technology relates to printing devices. [Background technology]

[0002] Conventionally, devices have been used that form images by ejecting fluid from a head onto a medium. For example, a fluid ejection device described in Patent Document 1 is capable of ejecting fluid (ink) by selecting one drive pulse from multiple drive pulses and applying it to a piezoelectric element at an appropriate timing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-142978 Summary of the Invention [Problem to be solved by the invention]

[0004] In the liquid ejecting device described in Patent Document 1, the electric charge discharged from the piezoelectric element (energy imparting element) flows to the ground, which tends to increase power consumption.

[0005] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a printing device that can suppress an increase in power consumption. [Means for solving the problem]

[0006] A printing device according to one embodiment of the present disclosure is a printing device comprising: a head including an energy imparting element and a nozzle that ejects liquid using the energy imparting element; and a voltage application circuit that applies a voltage to the energy imparting element, wherein the energy imparting element is a piezoelectric body in which a plurality of piezoelectric layers are stacked in a stacking direction, the piezoelectric body comprising: a first electrode formed on a first surface extending in an orthogonal direction perpendicular to the stacking direction; a second electrode provided at a position different from the first surface in the stacking direction and formed on a second surface extending in the orthogonal direction; and a third electrode provided at a position different from the first surface and the second surface in the stacking direction and extending in the orthogonal direction, the piezoelectric body comprising: a first active portion sandwiched between the first electrode and the second electrode in the stacking direction; and a second active portion sandwiched between the second electrode and the third electrode in the stacking direction, and the voltage application circuit comprising a first charging body connected to the first electrode or a second charging body connected to the second electrode. [Effects of the Invention]

[0007] In a printing device according to an embodiment of the present disclosure, it is possible to suppress an increase in power consumption. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view illustrating a printing device. [Figure 2] FIG. 2 is a simplified, partially enlarged cross-sectional view of the inkjet head. [Figure 3] FIG. 2 is an explanatory diagram showing a configuration example of a voltage application circuit. [Figure 4] FIG. 10 is an explanatory diagram illustrating an example of a switch control table. [Figure 5] 10 is a flowchart illustrating an example of a drying prevention process performed by a control unit of a control device. [Figure 6] FIG. 10 is a time chart showing the relationship between the charging voltage of the active part and switch control. [Figure 7] FIG. 10 is a time chart showing changes in charging voltage of first active parts associated with a plurality of nozzles. [Figure 8] 10 is a time chart showing changes in the charging voltage of second active parts associated with a plurality of nozzles. FIG. [Figure 9] 10 is a time chart showing the relationship between the charging voltage of the active section and switch control according to a modification of the first embodiment. FIG. [Figure 10] 10 is a time chart showing changes in charging voltage of first active parts for a plurality of nozzles according to the second embodiment. FIG. [Figure 11] 10 is a time chart showing changes in the charging voltage of second active parts associated with a plurality of nozzles according to the second embodiment. FIG. [Figure 12] FIG. 11 is a time chart showing changes in the charging voltage of the first active parts for the plurality of nozzles according to the third embodiment. [Figure 13] FIG. 11 is a time chart showing changes in the charging voltage of second active parts associated with a plurality of nozzles according to the third embodiment. [Figure 14] 10 is a flowchart showing an example of a drying prevention process performed by a control unit of a control device according to a fourth embodiment. [Figure 15] FIG. 10 is an explanatory diagram showing a configuration example of a voltage application circuit according to a fifth embodiment. [Figure 16] FIG. 10 is an explanatory diagram illustrating an example of an applied voltage table. [Figure 17] 10 is a flowchart showing an example of an applied voltage change process performed by a control unit of the control device. [Figure 18] FIG. 13 is a timing chart showing the relationship between the charging voltage of the active section and switch control when ink is ejected from the nozzle according to the sixth embodiment. [Figure 19] FIG. 4 is an explanatory diagram showing changes in the value of a current flowing through a second electrode. [Figure 20] FIG. 4 is an explanatory diagram showing changes in the value of a voltage applied to a second electrode. [Figure 21] FIG. 10 is an explanatory diagram showing a configuration example of a voltage application circuit according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Embodiment 1) The present invention will be described below with reference to the drawings showing a printing apparatus according to a first embodiment. FIG. 1 is a plan view showing a simplified view of the printing apparatus 1. In the following description, the front, back, left, and right directions shown in FIG. 1 will be used. The front and back directions correspond to the transport direction, and the left and right directions correspond to the scanning direction. The front side of FIG. 1 corresponds to the top, and the back side corresponds to the bottom, and the terms up and down will also be used.

[0010] 1, the printing device 1 includes a platen 2, an ink ejection device 3, and transport rollers 41 and 42. A recording medium, that is, a recording sheet 200, is placed on the upper surface of the platen 2. The ink ejection device 3 ejects ink onto the recording sheet 200 placed on the platen 2 to record an image. The ink ejection device 3 includes a carriage 6, a subtank 7, four inkjet heads (heads) 8, a circulation pump 10, and the like.

[0011] Two guide rails 11 and 12 extending laterally are provided above the platen 2 to guide the carriage 6. An endless belt 13 extending laterally is connected to the carriage 6. The endless belt 13 is driven by a carriage drive motor 14. As the endless belt 13 is driven, the carriage 6 is guided by the guide rails 11 and 12 and moves back and forth in the scanning direction in an area facing the platen 2. More specifically, the carriage 6, while supporting four inkjet heads 8, performs a first movement in which the heads are moved from one position to another from left to right in the scanning direction, and a second movement in which the heads are moved from another position to one position from right to left in the scanning direction.

[0012] A cap 20 and a flushing receiver 21 are provided between the guide rails 11 and 12. The cap 20 and the flushing receiver 21 are arranged below the ink ejection device 3. The cap 20 is arranged at the right end of the guide rails 11 and 12, and the flushing receiver 21 is arranged at the left end of the guide rails 11 and 12. The cap 20 and the flushing receiver 21 may be arranged left and right reversely.

[0013] The sub-tank 7 and four inkjet heads 8 are mounted on a carriage 6 and move back and forth in the scanning direction together with the carriage 6. The sub-tank 7 is connected to a cartridge holder 15 via a tube 17. Ink cartridges 16 of one or more colors (four colors in this embodiment) are attached to the cartridge holder 15. The four colors include, for example, black, yellow, cyan, and magenta.

[0014] Four ink chambers (liquid chambers) 71 are formed inside the subtank 7. The four ink chambers 71 store inks of four colors supplied from the four ink cartridges 16, respectively.

[0015] The four inkjet heads 8 are aligned in the scanning direction below the subtank 7. A plurality of nozzles 80 (see FIG. 2) are formed on the bottom surface of each inkjet head 8. One inkjet head 8 corresponds to one color of ink and is connected to one ink chamber 71. In other words, the four inkjet heads 8 correspond to four colors of ink, respectively, and are connected to four ink chambers 71, respectively.

[0016] The inkjet head 8 is provided with an ink supply port and an ink discharge port. The ink supply port and the ink discharge port are connected to an ink chamber 71 via a tube or the like, and form a circulation path. A circulation pump 10 is interposed between the ink supply port and the ink chamber 71.

[0017] Ink sent from the ink chamber 71 by the circulation pump 10 flows into the inkjet head 8 through the ink supply port and is ejected from the nozzles 80. Ink that is not ejected from the nozzles 80 returns to the ink chamber 71 through the ink outlet port. The ink circulates between the ink chamber 71 and the inkjet head 8. The four inkjet heads 8 eject the four colors of ink supplied from the subtanks 7 onto the recording paper 200 while moving together with the carriage 6 in the scanning direction.

[0018] As shown in FIG. 1, the transport roller 41 is disposed upstream (rearward) of the platen 2 in the transport direction. The transport roller 42 is disposed downstream (frontward) of the platen 2 in the transport direction. The two transport rollers 41 and 42 are driven synchronously by a motor (not shown). The two transport rollers 41 and 42 transport the recording paper 200 placed on the platen 2 in a transport direction perpendicular to the scanning direction. The printing apparatus 1 includes a control device 50. The control device 50 includes a control unit 51 (see FIG. 3) configured by a CPU or logic circuit (e.g., FPGA), a memory 52 such as a non-volatile memory and RAM, and performs various control processes by reading and executing a computer program (program product) stored in a portable recording medium 501. The computer program to be read may be pre-installed in the memory 52. ​​Alternatively, the computer program may be downloaded via a communication network (not shown) connected to the external device 100 and stored in the memory 52. ​​The control device 50 receives a driving job from the external device 100 and stores the program in the memory 52. The control device 50 controls the driving of the ink ejection device 3, the transport roller 41, etc. based on the driving job, and executes the printing process.

[0019] FIG. 2 is a simplified, partially enlarged cross-sectional view of the inkjet head 8. The inkjet head 8 includes a plurality of pressure chambers 81. The pressure chambers 81 are connected to nozzles 80 and form a plurality of pressure chamber rows. A vibration plate 82 is formed above the pressure chambers 81. A layered piezoelectric body 83 is formed above the vibration plate 82. The piezoelectric body 83 is formed by stacking a plurality of piezoelectric layers in the stacking direction (the up-and-down direction in FIG. 2). A third electrode (first common electrode) 84 is formed above each pressure chamber 81, between the piezoelectric body 83 and the vibration plate 82 (third surface).

[0020] A first electrode (second common electrode) 86 is provided inside the piezoelectric body 83. The first electrode 86 is arranged above each pressure chamber 81 and above the third electrode 84 (first surface). The first electrode 86 is arranged in a position not facing the third electrode 84. A second electrode (individual electrode) 85 is formed on the upper surface (second surface) of the piezoelectric body 83 above each pressure chamber 81. The first surface, second surface, and third surface extend in a direction perpendicular to the stacking direction and are provided at different positions in the stacking direction. The second electrode 85, the third electrode 84, and the first electrode 86 face each other above and below, sandwiching the piezoelectric body 83. The first electrode 86, the second electrode 85, and the piezoelectric body 83 (piezoelectric layer) between the first electrode 86 and the second electrode 85 form a first active section 88 (see FIG. 3) that overlaps with the pressure chamber 81 in the stacking direction. The second electrode 85, the third electrode 84, and the piezoelectric body 83 (piezoelectric layer) between the second electrode 85 and the third electrode 84 form a second active section 89 (see FIG. 3) that overlaps with the pressure chamber 81 in the stacking direction. The first active section 88 and the second active section 89 constitute an actuator. The vibration plate 82, the piezoelectric body 83, the first electrode 86, the second electrode 85, and the third electrode 84 constitute an energy imparting element.

[0021] A nozzle plate 87 is provided below each pressure chamber 81. A plurality of nozzles 80 are formed in the nozzle plate 87, penetrating vertically. Each nozzle 80 is disposed below each pressure chamber 81. The plurality of nozzles 80 constitute a plurality of nozzle rows extending along the row of pressure chambers. Each nozzle 80 ejects liquid by driving a first active portion 88 and a second active portion 89 (actuator). Note that in the following description, driving a nozzle 80 and driving an actuator will be considered to be synonymous.

[0022] The third electrode 84 is connected to a COM terminal, which in this embodiment is ground, and the first electrode 86 is connected to a VCOM terminal. The VCOM voltage is higher than the COM voltage. The second electrode 85 is connected to the SCOM terminal (see FIG. 3) via a first switch 91. The SCOM voltage is lower than the VCOM voltage and higher than the COM voltage. The voltage value of the SCOM voltage is, for example, half the voltage value of the VCOM voltage. A high or low voltage is applied to the second electrode 85 by the voltage, which deforms the piezoelectric element 83 and vibrates the diaphragm 82. The vibration of the diaphragm 82 causes ink to be ejected from the pressure chamber 81 via the nozzle 80.

[0023] 3 is an explanatory diagram showing an example of the configuration of a voltage application circuit. The voltage application circuit includes a main power supply (VCOM), a sub-power supply (SCOM), a plurality of first switches 91, second switches 92, third switches 93, first activation units 88, second activation units 89, and a plurality of resistors corresponding to each nozzle 80. Note that to avoid complication of the drawing, the reference symbols for the resistors are omitted in FIG. 3.

[0024] One end (first electrode 86 side) of the first active unit 88 is connected to the main power supply (VCOM). The other end (second electrode 85 side) of the first active unit 88 is connected to one end (second electrode side) of the second active unit 89. The other end of the first active unit 88 is connected to the sub-power supply (SCOM) via two resistors and a first switch 91. The other end of the first active unit 88 is connected to the main power supply (VCOM) via two resistors and a second switch 92, and to ground (COM) via two resistors and a third switch 93. That is, when the first switch 91 is turned on, a SCOM voltage is applied to the second electrode 85 (the other end of the first active unit 88). When the second switch 92 is turned on, a VCOM voltage is applied to the second electrode 85. When the third switch 93 is turned on, a COM voltage is applied to the second electrode 85. The other end (third electrode 84) of the second active unit 89 is connected to ground (COM). That is, the first switch 91 switches between the presence and absence of an electrical connection between the sub-power supply (SCOM) and the second electrode 85. The second switch 92 switches between the presence and absence of an electrical connection between the main power supply (VCOM) and the second electrode 85. The third switch 93 switches between the presence and absence of an electrical connection between the ground (COM) and the second electrode.

[0025] The multiple pressure chambers 81 include a first pressure chamber 81(1), a second pressure chamber 81(2), ..., and an nth pressure chamber. The multiple nozzles 80 include a first nozzle 80(1), a second nozzle 80(2), ..., and an nth nozzle 80(n) that connect the first pressure chamber 81(1), the second pressure chamber 81(2), ..., and the nth pressure chamber, respectively. The multiple first active portions 88 correspond to the first nozzle 80(1), the second nozzle 80(2), ..., and the nth nozzle 80(n), and include a first active portion 88(1), a first active portion 88(2), ..., and a first active portion 88(n) that overlap the first pressure chamber 81(1), the second pressure chamber 81(2), ..., and the nth pressure chamber, respectively, in the stacking direction. The multiple second active portions 89 correspond to the first nozzle 80(1), the second nozzle 80(2), ..., and the nth nozzle 80(n), and include second active portions 89(1), 89(2), ..., and 89(n) that overlap with the first pressure chamber 81(1), the second pressure chamber 81(2), ..., and the nth pressure chamber, respectively, in the stacking direction. One end of each of the first active portions 88(1), 88(2), ..., 88(n) is connected to the main power supply (VCOM). Furthermore, one end of each of the second active portions 89(1), 89(2), ..., 89(n) is connected to the other end of each of the first active portions 88(1), 88(2), ..., 88(n). The energy application elements including the first and second active portions 88 and 89 correspond to the nozzles 80 (80(1), 80(2), ..., 80(n)). That is, the nozzle 80(1) (first nozzle) ejects liquid by driving the first and second active portions 88(1) and 89(1), the nozzle 80(2) (second nozzle) ejects liquid by driving the first and second active portions 88(2) and 89(2), and the nozzle 80(n) (nth nozzle) ejects or vibrates the liquid by driving the first and second active portions 88(n) and 89(n). n is the number of nozzles 80 included in the inkjet head 8. Hereinafter, the first active portion 88(k) and the second active portion 89(k) that cause the kth nozzle 80(k) to eject liquid will be referred to as the first active portion 88(k) and the second active portion 89(k) associated with the kth nozzle 80(k), where k is an integer between 1 and n.

[0026] A first switch 91, a second switch 92, and a third switch 93 corresponding to the first active unit 88 and the second active unit 89 are connected to the second electrode 85 between the first active unit 88 and the second active unit 89. That is, a first switch 91(1), a second switch 92(1), and a third switch 93(1) are connected to the first active unit 88(1) and the second active unit 89(1), a first switch 91(2), a second switch 92(2), and a third switch 93(2) are connected to the first active unit 88(n) and the second active unit 89(n). That is, a first switch 91(k), a second switch 92(k), and a third switch 93(k) are connected to the first active section 88(k) and the second active section 89(k). The multiple first switches 91(1) to 91(n), the second switches 92(1) to 92(n), and the third switches 93(1) to 93(n) constitute a switch group 9. Hereinafter, the first switch 91(k), the second switch 92(k), and the third switch 93(k) corresponding to the first active section 88(k) and the second active section 89(k) of the kth nozzle 80(k) will be referred to as the first switch 91(k), the second switch 92(k), and the third switch 93(k) associated with the kth nozzle 80(k).

[0027] The first capacitor C1 is provided so as to be connected in parallel to the main power supply. The first capacitor C1 is capable of storing electric charge discharged from one end of the first active unit 88. Furthermore, the first capacitor C1 is capable of applying a voltage to one end (first electrode 86) of the first active unit 88 by discharging electric charge. The second capacitor C2 is provided so as to be connected in parallel to the sub-power supply. The second capacitor C2 is capable of storing electric charge discharged from one end of the second active unit 89. Furthermore, the second capacitor C2 is capable of applying a voltage to the other end of the first active unit 88 or one end (second electrode 85) of the second active unit 89 by discharging electric charge.

[0028] The control device 50 includes a control unit 51, a memory 52, and a signal output unit 53. The memory 52 stores a switch control table 521 that stores information indicating the switches included in the switch group 9 that are turned on corresponding to the elapsed time since the control device 50 started controlling the voltage application circuit. The control unit 51 has a timer function, and causes the signal output unit 53 to output a switch control signal S1 that turns on or off the switch corresponding to the elapsed time read from the switch control table 521 in the memory 52.

[0029] FIG. 4 is an explanatory diagram showing an example of the switch control table 521. The management items of the switch control table 521 include, for example, a time slot field, an elapsed time field, and a switch control field. The time slot field stores the number of a time slot, which is a predetermined interval dividing the time elapsed since the control device 50 started to control the voltage application circuit. Note that the length of time of each time slot does not have to be constant. The elapsed time field stores the range of the time elapsed (ms: milliseconds) since the control device 50 started to control the voltage application circuit, corresponding to each time slot. The switch control field stores the number (code) of the switch included in the switch group 9 that is on or off at the start of each time slot, and the type of control (on or off).

[0030] Before the control device 50 starts controlling the voltage application circuit, all of the first switches 91(1) to 91(n) and all of the second switches 92(1) to 92(n) are turned off, and all of the third switches 93(1) to 93(n) are turned on. When the control device 50 starts controlling the voltage application circuit, it switches on and off the switches associated with each nozzle 80 to perform a non-ejection flushing process on the nozzles 80, starting with the first nozzle 80(1) and continuing through the nth nozzle 80(n). The non-ejection flushing process is a maintenance process that vibrates the ink surface (meniscus) inside the nozzles 80 to prevent the nozzles 80 from drying out. The non-ejection flushing process prevents the nozzles 80 from ejecting ink. For example, when the control device 50 receives a drive job for a non-ejection flushing process from the external device 100, it starts controlling the voltage control circuit to perform the non-ejection flushing process on the nozzles 80, and ends control of the voltage application circuit when the non-ejection flushing process for all of the nozzles 80 is completed. That is, the switch control table 521 stores records relating to the time slots until all the nozzles 80 have undergone the non-ejection flushing process.

[0031] FIG. 5 is a flowchart showing an example of a drying prevention process performed by the control unit 51 of the control device 50. The control unit 51 of the control device 50 determines whether or not to execute a non-ejection flushing process (S1). In S1, the control unit 51 determines to execute the non-ejection flushing process, for example, if it has received a drive job for the non-ejection flushing process from the external device 100. The control unit 51 may execute the non-ejection flushing process periodically, or may determine in S1 whether or not it is time to execute the non-ejection flushing process. If the non-ejection flushing process is not to be executed (S1: NO), the control unit 51 returns the process to S1 and waits until the non-ejection flushing process is executed. If the non-ejection flushing process is to be executed (S1: YES), the control unit 51 reads the switch control table 521 from the memory 52 (S2). The control unit 51 starts measuring time using a timer function (S3). The control unit 51 controls the on / off of each switch in the switch group 9 based on the read switch control table 521 and the measured elapsed time (S4), and then ends the process.

[0032] FIG. 6 is a time chart showing the relationship between the charging voltage of the active unit and switch control. FIG. 6 shows a time chart from time slot (3k-2) to time slot (3k+3). That is, FIG. 6 shows the charging voltage of the first active unit 88(k) and the second active unit 89(k) associated with the first nozzle 80(k), as well as the control of the first switch 91(k), the second switch 92(k), and the third switch 93(k). In FIG. 6, the change in the charging voltage of the first active unit 88 is indicated by a thin line, and the change in the charging voltage of the second active unit 89 is indicated by a thick line. The same applies to FIGS. 9 and 18.

[0033] Until control of the first switch 91, second switch 92, and third switch 93 associated with the nozzle 80 begins, the first switch 91 and second switch 92 are off, and the third switch 93 is on. That is, the COM voltage is applied to the second electrode 85 (see FIG. 3). In this embodiment, the COM terminal is connected to ground, and the COM voltage is 0 V. Furthermore, the VCOM voltage is always applied to the first electrode 86, and the COM voltage is always applied to the third electrode 84. Therefore, until control of the first switch 91, second switch 92, and third switch 93 begins, the charging voltage of the first active unit 88 is the VCOM voltage, and the charging voltage of the second active unit 89 is the COM voltage.

[0034] When control of the first switch 91, second switch 92, and third switch 93 associated with the kth nozzle 80(k) begins, the first switch 91 is turned on and the third switch 93 is turned off in the first time slot (3k-2). That is, the SCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 discharges electric charge from one end (first electrode 86), and the charging voltage of the first active unit 88 becomes the VCOM voltage minus the SCOM voltage. Note that in this embodiment, the voltage value of the SCOM voltage is half the voltage value of the VCOM voltage, so the charging voltage of the first active unit 88 becomes the SCOM voltage. Furthermore, the second active unit 89 stores electric charge from one end, and the charging voltage of the second active unit 89 becomes the SCOM voltage.

[0035] After control for the kth nozzle 80(k) begins, in the second time slot (3k-1), the second switch 92 is turned on and the first switch 91 is turned off. That is, the VCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 discharges electric charge from one end, and the charging voltage of the first active unit 88 becomes the COM voltage (0 V). Also, the second active unit 89 charges electric charge from one end, and the charging voltage of the second active unit 89 becomes the VCOM voltage.

[0036] After control for the kth nozzle 80(k) begins, in the third time slot (3k), the switch is not switched, the charging voltage of the first active unit 88 remains at the COM voltage (0V), and the charging voltage of the second active unit 89 remains at the VCOM voltage.

[0037] After control for the kth nozzle 80(k) begins, the first switch 91 is turned on and the second switch 92 is turned off in the fourth time slot (3k+1). That is, the SCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 is charged from one end, and the charging voltage of the first active unit 88 becomes the VCOM voltage minus the SCOM voltage. Note that in this embodiment, the SCOM voltage is half the VCOM voltage, so the charging voltage of the first active unit 88 becomes the SCOM voltage. Furthermore, the second active unit 89 is discharged from one end, and the charging voltage of the second active unit 89 becomes the SCOM voltage.

[0038] After control for the kth nozzle 80(k) begins, in the fifth time slot (3k+2), the third switch 93 is turned on and the first switch 91 is turned off. That is, the COM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 is charged from one end, and the charging voltage of the first active unit 88 becomes the VCOM voltage. Also, the second active unit 89 is discharged from one end, and the charging voltage of the second active unit 89 becomes the COM voltage.

[0039] After control for the kth nozzle 80(k) begins, in the sixth time slot (3k+3), the switch is not switched, the charging voltage of the first active unit 88 remains at the VCOM voltage, and the charging voltage of the second active unit 89 remains at the COM voltage (0V).

[0040] FIG. 7 is a time chart showing changes in the charging voltage of the first activators 88 associated with the multiple nozzles 80. The changes in the charging voltage of each first activator 88 are as shown in FIG. 6. The first activator 88(1) associated with the first nozzle 80(1) charges from the COM voltage to the SCOM voltage in time slot (4). The first activator 88(2) associated with the second nozzle 80(2) discharges from the VCOM voltage to the SCOM voltage in time slot (4). Because the first activator 88(1) associated with the first nozzle 80(1) and the first activator 88(2) associated with the second nozzle 80(2) are electrically connected, the charge discharged by the first activator 88(2) associated with the second nozzle 80(2) is stored in the first activator 88(1) associated with the first nozzle 80(1). That is, in this embodiment, the first active portion 88(1) associated with the first nozzle 80(1) (which overlaps with the first pressure chamber 81(1) in the stacking direction) corresponds to the first charge body. Note that if the charge discharged by the first active portion 88(2) associated with the second nozzle 80(2) is in excess of the charge stored in the first active portion 88(1) associated with the first nozzle 80(1), the excess charge may be stored in the first capacitor C1. That is, the first capacitor C1 may correspond to the first charge body. Also, if the charge discharged by the first active portion 88(2) associated with the second nozzle 80(2) is insufficient compared to the charge stored in the first active portion 88(1) associated with the first nozzle 80(1), the charge discharged by the first capacitor C1 may be stored in the first active portion 88(1) associated with the first nozzle 80(1).

[0041] Similarly, the first active section 88(k) associated with the kth nozzle 80(k) charges from the COM voltage to the SCOM voltage during time slot (3k+1). The first active section 88(k+1) associated with the k+1th nozzle 80(k+1) discharges from the VCOM voltage to the SCOM voltage during time slot (3k+1). Because the first active section 88(k) associated with the kth nozzle 80(k) and the first active section 88(k+1) associated with the k+1th nozzle 80(k+1) are electrically connected, the charge discharged by the first active section 88(k+1) associated with the k+1th nozzle 80(k+1) is stored in the first active section 88(k) associated with the kth nozzle 80(k). In other words, in this embodiment, the first active section 88(k) associated with the kth nozzle 80(k) (which overlaps with the first pressure chamber 81(k) in the stacking direction) corresponds to the first charge body. If the charge discharged by the first active unit 88(k+1) associated with the k+1th nozzle 80(k+1) is in excess of the charge charged to the first active unit 88(k) associated with the kth nozzle 80(k), the excess charge may be charged to the first capacitor C1. That is, the first capacitor C1 may correspond to the first charge body. Furthermore, if the charge discharged by the first active unit 88(k+1) associated with the k+1th nozzle 80(k+1) is insufficient compared to the charge charged to the first active unit 88(k) associated with the kth nozzle 80(k), the charge discharged by the first capacitor C1 may be charged to the first active unit 88(k) associated with the kth nozzle 80(k).

[0042] FIG. 8 is a time chart showing changes in the charging voltage of the second activation units 89 associated with multiple nozzles 80. The changes in the charging voltage of each second activation unit 89 are as shown in FIG. 6. The second activation unit 89(1) associated with the first nozzle 80(1) discharges from the VCOM voltage to the SCOM voltage in time slot (4). At this time, the first switch 91(1) is on. The second activation unit 89(2) associated with the second nozzle 80(2) charges from the COM voltage to the SCOM voltage in time slot (4). At this time, the first switch 91(2) is on. In other words, the second activation unit 89(1) associated with the first nozzle 80(1) and the second activation unit 89(2) associated with the second nozzle 80(2) are electrically connected, and the charge discharged by the second activation unit 89(1) associated with the first nozzle 80(1) is stored in the second activation unit 89(2) associated with the second nozzle 80(2). That is, in this embodiment, the second active portion 89(2) associated with the second nozzle 80(2) (which overlaps with the second pressure chamber 81(2) in the stacking direction) corresponds to the second charge body. Note that if the charge discharged by the second active portion 89(1) associated with the first nozzle 80(1) is in excess of the charge stored in the second active portion 89(2) associated with the second nozzle 80(2), the excess charge may be stored in the second capacitor C2. That is, the second capacitor C2 may correspond to the second charge body. Also, if the charge discharged by the second active portion 89(1) associated with the first nozzle 80(1) is insufficient compared to the charge stored in the second active portion 89(2) associated with the second nozzle 80(2), the charge discharged by the second capacitor C2 may be stored in the second active portion 89(2) associated with the second nozzle 80(2). That is, the first switch 91 switches between electrical connection and disconnection between the second electrode 85 and the second charge body.

[0043] Similarly, the second active unit 89(k) associated with the kth nozzle 80(k) discharges from the VCOM voltage to the SCOM voltage in time slot (3k+1). At this time, the first switch 91(k) is on. The second active unit 89(k+1) associated with the k+1th nozzle 80(k+1) charges from the COM voltage to the SCOM voltage in time slot (3k+1). At this time, the first switch 91(k+1) is on. That is, the second active unit 89(k) associated with the kth nozzle 80(k) and the second active unit 89(k+1) associated with the k+1th nozzle 80(k+1) are electrically connected, and the charge discharged by the second active unit 89(k) associated with the kth nozzle 80(k) is stored in the second active unit 89(k+1) associated with the k+1th nozzle 80(k+1). That is, in this embodiment, the second active portion 89(k+1) associated with the k+1-th nozzle 80(k+1) (which overlaps with the k+1-th pressure chamber 81(k+1) in the stacking direction) corresponds to the second charged body. Note that if the charge discharged by the second active portion 89(k) associated with the k-th nozzle 80(k) is in excess of the charge charged to the second active portion 89(k+1) associated with the k+1-th nozzle 80(k+1), the excess charge may be charged to the second capacitor C2. That is, the second capacitor C2 may correspond to the second charged body. Note that if the charge discharged by the second active portion 89(k) associated with the k-th nozzle 80(k) is insufficient compared to the charge charged to the second active portion 89(k+1) associated with the k+1-th nozzle 80(k+1), the charge discharged by the second capacitor C2 may be charged to the second active portion 89(k+1) associated with the k+1-th nozzle 80(k+1).

[0044] According to the above configuration and process, the charge discharged by the first activation unit 88 associated with a nozzle 80 is stored in and regenerated by the first activation unit 88 associated with another nozzle 80. Furthermore, the charge discharged by the second activation unit 89 associated with a nozzle 80 is stored in and regenerated by the second activation unit 89 associated with another nozzle 80. This makes it possible to store the charge discharged by an energy imparting element in another energy imparting element, thereby reducing the charge supplied to the energy imparting element by the main power supply.

[0045] (Modification of the first embodiment) 9 is a time chart showing the relationship between the charging voltage of the active section and switch control according to a modification of the first embodiment. In the first embodiment, the SCOM voltage is half the VCOM voltage, but this is not limiting. In FIG. 9, a case where the SCOM voltage is less than half the VCOM voltage is described.

[0046] Until control of the first switch 91, second switch 92, and third switch 93 associated with the nozzle 80 begins, the first switch 91 and second switch 92 are off, and the third switch 93 is on. That is, the COM voltage is applied to the second electrode 85 (see FIG. 3). In this embodiment, the COM terminal is connected to ground, and the COM voltage is 0 V. Furthermore, the VCOM voltage is always applied to the first electrode 86, and the COM voltage is always applied to the third electrode 84. Therefore, until control of the first switch 91, second switch 92, and third switch 93 begins, the charging voltage of the first active unit 88 is the VCOM voltage, and the charging voltage of the second active unit 89 is the COM voltage.

[0047] When control of the first switch 91, second switch 92, and third switch 93 associated with the kth nozzle 80(k) begins, the first switch 91 is turned on and the third switch 93 is turned off in the first time slot (3k-2). That is, the SCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 discharges charge from one end, and the charging voltage of the first active unit 88 becomes the value obtained by subtracting the SCOM voltage from the VCOM voltage (VCOM voltage - SCOM voltage). Also, the second active unit 89 is charged from one end, and the charging voltage of the second active unit 89 becomes the SCOM voltage.

[0048] After control for the kth nozzle 80(k) begins, in the second time slot (3k-1), the second switch 92 is turned on and the first switch 91 is turned off. That is, the VCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 discharges electric charge from one end, and the charging voltage of the first active unit 88 becomes the COM voltage (0 V). Also, the second active unit 89 charges electric charge from one end, and the charging voltage of the second active unit 89 becomes the VCOM voltage.

[0049] After control for the kth nozzle 80(k) begins, in the third time slot (3k), the switch is not switched, the charging voltage of the first active unit 88 remains at the COM voltage (0V), and the charging voltage of the second active unit 89 remains at the VCOM voltage.

[0050] After control for the kth nozzle 80(k) begins, the first switch 91 is turned on and the second switch 92 is turned off in the fourth time slot (3k+1). That is, the SCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 is charged from one end, and the charging voltage of the first active unit 88 becomes the value obtained by subtracting the SCOM voltage from the VCOM voltage (VCOM voltage - SCOM voltage). Also, the second active unit 89 is discharged from one end, and the charging voltage of the second active unit 89 becomes the SCOM voltage.

[0051] After control for the kth nozzle 80(k) begins, in the fifth time slot (3k+2), the third switch 93 is turned on and the first switch 91 is turned off. That is, the COM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 is charged from one end, and the charging voltage of the first active unit 88 becomes the VCOM voltage. Also, the second active unit 89 is discharged from one end, and the charging voltage of the second active unit 89 becomes the COM voltage.

[0052] After control for the kth nozzle 80(k) begins, in the sixth time slot (3k+3), the switch is not switched, the charging voltage of the first active unit 88 remains at the VCOM voltage, and the charging voltage of the second active unit 89 remains at the COM voltage (0V).

[0053] In this modification, the fluctuation range of the voltage of the first active unit 88 or the second active unit 89 varies depending on the time slot, so the time length of each time slot is uneven. As shown in Figure 9, when the SCOM voltage is lower than half the VCOM voltage, time slots (3k-2) and (3k+2) are shorter than time slots (3k-1) and (3k+1).

[0054] (Embodiment 2) The following description is based on the drawings showing a printing device 1 according to a second embodiment. Among the components according to the second embodiment, components similar to those according to the first embodiment are assigned the same reference numerals, and detailed description thereof will be omitted. The control unit 51 of the control device 50 according to the second embodiment does not simultaneously turn on the first switches 91 for multiple different nozzles 80. That is, the discharging of the first activator 88 for each nozzle 80 is performed in a different time slot from the charging of the first activator 88 for the other nozzles 80, and the discharging of the second activator 89 for each nozzle 80 is performed in a different time slot from the charging of the second activator 89 for the other nozzles 80. At this time, the charge discharged from the first activator 88 is charged to the first capacitor C1, and the charge discharged from the second activator 89 is charged to the second capacitor C2.

[0055] 10 is a time chart showing changes in the charging voltage of the first activation units 88 associated with the plurality of nozzles 80 according to the second embodiment. The control unit 51 of the control device 50 controls the on / off state of the first switch 91(1), the second switch 92(1), or the third switch 93(1) associated with the first nozzle 80(1) during time slots (1) to (5), thereby causing the first activation unit 88(1) to discharge and charge. After completing the on / off control of the first switch 91(1), the second switch 92(1), or the third switch 93(1) associated with the first nozzle 80(1), the control unit 51 controls the on / off state of the first switch 91(2), the second switch 92(2), or the third switch 93(2) associated with the second nozzle 80(2) during time slots (6) to (10). As a result, when the first active unit 88(2) associated with the second nozzle 80(2) discharges electric charge in time slot (6), the other nozzles 80 do not have any first active units 88 to charge, so the electric charge discharged by the first active unit 88(2) is stored in the first capacitor C1 (see FIG. 3). That is, in this embodiment, the first capacitor C1 corresponds to the first charge body. Also, when the first active unit 88(2) associated with the second nozzle 80(2) stores electric charge in time slot (9), the other nozzles 80 do not have any first active units 88 to discharge, so the first active unit 88(2) stores the electric charge discharged by the first capacitor C1.

[0056] Similarly, after completing on / off control of the first switch 91(k-1), second switch 92(k-1), or third switch 93(k-1) associated with the k-1-th nozzle 80(k-1), the control unit 51 of the control device 50 executes on / off control of the first switch 91(k), second switch 92(k), or third switch 93(k) associated with the k-th nozzle 80(k) in time slots (5k-4) to (5k). As a result, when the first active unit 88(k) associated with the k-th nozzle 80(k) discharges electric charge in time slot (5k-4), since there are no first active units 88 in the other nozzles 80 to store electric charge, the electric charge discharged by the first active unit 88(k) is stored in the first capacitor C1 (see FIG. 3). Furthermore, when the first active unit 88(k) associated with the kth nozzle 80(k) stores electric charge in time slot (5k-1), since there are no first active units 88 in the other nozzles 80 to discharge electric charge, the first active unit 88(k) stores the electric charge discharged by the first capacitor C1.

[0057] 11 is a time chart showing changes in the charging voltage of the second activation unit 89 associated with the plurality of nozzles 80 according to the second embodiment. The control unit 51 of the control device 50 controls the on / off of the first switch 91(1), the second switch 92(1), or the third switch 93(1) associated with the first nozzle 80(1) during time slots (1) to (5), thereby charging and discharging the second activation unit 89(1). After completing the on / off control of the first switch 91(1), the second switch 92(1), or the third switch 93(1) associated with the first nozzle 80(1), the control unit 51 controls the on / off of the first switch 91(2), the second switch 92(2), or the third switch 93(2) associated with the second nozzle 80(2) during time slots (6) to (10). As a result, when the second active unit 89(2) associated with the second nozzle 80(2) is charged in time slot (6), there are no second active units 89 in the other nozzles 80 to discharge the charge from, so the second active unit 89(2) stores the charge discharged by the second capacitor C2. Also, when the second active unit 89(2) associated with the second nozzle 80(2) is discharged in time slot (9), there are no second active units 89 in the other nozzles 80 to charge from, so the charge discharged by the second active unit 89(2) is stored in the second capacitor C2 (see FIG. 3). That is, in this embodiment, the second capacitor C2 corresponds to the second charge body.

[0058] Similarly, after completing on / off control of the first switch 91(k-1), second switch 92(k-1), or third switch 93(k-1) associated with the k-1th nozzle 80(k-1), the control unit 51 of the control device 50 executes on / off control of the first switch 91(k), second switch 92(k), or third switch 93(k) associated with the kth nozzle 80(k) in time slots (5k-4) to (5k). As a result, when the second activation unit 89(k) associated with the kth nozzle 80(k) is charged in time slot (5k-4), since there is no second activation unit 89 associated with the other nozzles 80 to charge, the second activation unit 89(k) charges up the charge discharged by the second capacitor C2. Furthermore, when the second active unit 89(k) associated with the kth nozzle 80(k) discharges electric charge in time slot (5k-1), since there is no second active unit 89 in the other nozzles 80 to discharge electric charge from, the electric charge discharged by the second active unit 89(k) is stored in the second capacitor C2 (see Figure 3).

[0059] (Embodiment 3) The following description is based on the drawings showing a printing device 1 according to the third embodiment. The same components as those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted. The nozzles 80 according to the third embodiment are divided into groups. The control unit 51 of the control device 50 executes the same on / off control in the same time slot for the first switch 91, second switch 92, and third switch 93 associated with the nozzles 80 in the same group. In other words, the fluctuations in the charging voltage of the first activation unit 88 or second activation unit 89 associated with the nozzles 80 in the same group are similar.

[0060] FIG. 12 is a time chart showing changes in the charging voltage of the first activators 88 associated with the plurality of nozzles 80 according to the third embodiment. In this embodiment, each group includes two nozzles 80. That is, the k-th group includes the 2k-1st nozzle 80(2k-1) and the 2kth nozzle 80(2k). The first switch 91(2k-1), the second switch 92(2k-1), and the third switch 93(2k-1) associated with the 2k-1st nozzle 80(2k-1) and the first switch 91(2k), the second switch 92(2k), and the third switch 93(2k) associated with the 2kth nozzle 80(2k) are controlled on and off in the same time slot. As a result, the charging voltage of the first activator 88(2k-1) associated with the 2k-1st nozzle 80(2k-1) and the first activator 88(2k) associated with the 2kth nozzle 80(2k) fluctuate in the same time slot.

[0061] The first active unit 88(2k-1) and the first active unit 88(2k) of the kth group charge from the COM voltage to the SCOM voltage in time slot (3k+1). The first active unit 88(2k+1) and the first active unit 88(2k+2) of the k+1th group discharge from the VCOM voltage to the SCOM voltage in time slot (3k+1). Because the first active unit 88(2k-1) and the first active unit 88(2k) of the kth group are electrically connected to the first active unit 88(2k+1) and the first active unit 88(2k+2) of the k+1th group, the charge discharged by the first active unit 88(2k+1) and the first active unit 88(2k+2) of the k+1th group is stored in the first active unit 88(2k-1) and the first active unit 88(2k) of the kth group. If the charge discharged by the first active unit 88(2k+1) and the first active unit 88(2k+2) of the k+1th group is in excess of the charge charged to the first active unit 88(2k-1) and the first active unit 88(2k) of the kth group, the excess charge may be charged to the first capacitor C1. If the charge discharged by the first active unit 88(2k+1) and the first active unit 88(2k+2) of the k+1th group is insufficient compared to the charge charged to the first active unit 88(2k-1) and the first active unit 88(2k) of the kth group, the charge discharged by the first capacitor C1 may be charged to the first active unit 88(2k-1) and the first active unit 88(2k) of the kth group.

[0062] 13 is a time chart showing changes in the charging voltage of the second activation unit 89 associated with the plurality of nozzles 80 according to the third embodiment. As described above, the first switch 91(2k-1), the second switch 92(2k-1), and the third switch 93(2k-1) associated with the 2k-1st nozzle 80(2k-1) and the first switch 91(2k), the second switch 92(2k), and the third switch 93(2k) associated with the 2kth nozzle 80(2k) are controlled on and off in the same manner in the same time slot. As a result, the charging voltage of the second activation unit 89(2k-1) associated with the 2k-1st nozzle 80(2k-1) and the second activation unit 89(2k) associated with the 2kth nozzle 80(2k) fluctuate in the same manner in the same time slot.

[0063] The second active unit 89(2k-1) and the second active unit 89(2k) of the kth group discharge electric charge from the VCOM voltage to the SCOM voltage in time slot (3k+1). At this time, the first switch 91(k) is on. Also, the second active unit 89(2k+1) and the second active unit 89(2k+2) of the k+1th group charge electric charge from the COM voltage to the SCOM voltage in time slot (3k+1). At this time, the first switch 91(k+1) is on. That is, the second active unit 89(2k-1) and the second active unit 89(2k) of the kth group are electrically connected to the second active unit 89(2k+1) and the second active unit 89(2k+2) of the k+1th group, and the charge discharged by the second active unit 89(2k-1) and the second active unit 89(2k) of the kth group is charged to the second active unit 89(2k+1) and the second active unit 89(2k+2) of the k+1th group. Note that if the charge discharged by the second active unit 89(2k-1) and the second active unit 89(2k) of the kth group is in excess of the charge charged to the second active unit 89(2k+1) and the second active unit 89(2k+2) of the k+1th group, the excess charge may be charged to the second capacitor C2. Furthermore, if the charge discharged by the second active unit 89(2k-1) and the second active unit 89(2k) of the kth group is insufficient compared to the charge charged to the second active unit 89(2k+1) and the second active unit 89(2k+2) of the k+1th group, the charge discharged by the second capacitor C2 may be charged to the second active unit 89(2k+1) and the second active unit 89(2k+2) of the k+1th group.

[0064] (Embodiment 4) The following description is based on the drawings showing a printing device 1 according to a fourth embodiment. Among the components according to the fourth embodiment, components similar to those according to the first embodiment are assigned the same reference numerals, and detailed description thereof will be omitted. The control unit 51 of the control device 50 according to the fourth embodiment receives print data, for example, from the external device 100, and, based on the received print data, identifies the nozzles 80 that will eject ink or the nozzles 80 that will not eject ink when executing a print job related to the print data. When the control unit 51 subsequently acquires a drive job for a non-ejection flushing process, the control unit 51 performs on-off control of each switch based on the switch control table 521, but does not perform on-off control related to the non-ejection flushing process for the first switch 91, the second switch 92, and the third switch 93 associated with the nozzles 80 that eject ink. As a result, the control unit 51 discharges electric charge only from the first activation unit 88 or the second activation unit 89 associated with the nozzles 80 that are not executing the process of ejecting ink based on the print data, thereby executing the non-ejection flushing process for those nozzles 80.

[0065] FIG. 14 is a flowchart showing an example of a drying prevention process performed by the control unit 51 of the control device 50 according to the fourth embodiment. The control unit 51 of the control device 50 acquires print data from the external device 100 (S11). The control unit 51 starts executing a print job based on the acquired print data (S12). The control unit 51 determines whether or not to execute a non-ejection flushing process (S13). In S13, for example, if the control unit 51 has received a drive job for a non-ejection flushing process from the external device 100, the control unit 51 determines to execute the non-ejection flushing process. Note that the control unit 51 may periodically execute the non-ejection flushing process, or may determine in S13 whether or not it is time to execute the non-ejection flushing process. If the non-ejection flushing process is not to be executed (S13: NO), the control unit 51 returns the process to S13 and waits until the non-ejection flushing process is executed.

[0066] If the non-ejection flushing process is to be executed (S13: YES), the control unit 51 reads the switch control table 521 from the memory 52 (S14). Based on the print data acquired in S11, the control unit 51 identifies the nozzles 80 that will not eject liquid in the print job started in S12 (S15). In S15, the control unit 51 analyzes, for example, image data included in the print data, and calculates the nozzles 80 that need to eject liquid (ink) to reproduce and print the image, thereby identifying the nozzles 80 that will not eject liquid in the print job. Note that the print data may also indicate the nozzles that need to eject liquid in the print job. The control unit 51 starts timing using a timer function (S16). Of the switches that are subject to on / off control and are stored in the read switch control table 521, the control unit 51 executes on / off control of each switch associated with the nozzles 80 identified in S15 based on the measured elapsed time (S17), and then ends the process. Note that the execution of the print job started in S12 continues as a subprocess. Furthermore, the control unit 51 does not execute on / off control for the non-ejection flushing process for the switches associated with the nozzles 80 that eject the identified liquid, but executes on / off control for the switches associated with the nozzles 80 associated with the print job. Note that the control unit 51 does not need to execute the anti-drying process if all nozzles 80 eject ink during the printing process. Furthermore, the control unit 51 may terminate the anti-drying process if it determines in S11, S12, or S15 that all nozzles 80 do not eject ink.

[0067] (Embodiment 5) The following description is based on the drawings showing a printing device 1 according to the fifth embodiment. Of the configuration according to the fifth embodiment, the same configuration as in the first embodiment is given the same reference numerals, and detailed description thereof will be omitted. The control unit 51 of the control device 50 according to the fifth embodiment changes the voltage output by the main power supply (VCOM) or the sub power supply (SCOM) in accordance with the state of the nozzles 80 obtained.

[0068] FIG. 15 is an explanatory diagram showing a configuration example of a voltage application circuit according to a fifth embodiment. The voltage application circuit according to the fifth embodiment includes a variable resistor group R including a plurality of first variable resistors R1(1) to R1(n) and a plurality of second variable resistors R2(1) to R2(n). The first variable resistor R1 and the second variable resistor R2 are resistors that can change the voltage value of the output current relative to the voltage value of the input current by, for example, changing the distance between the current input terminal and the output terminal in response to an input signal. The control unit 51 of the control device 50 outputs a voltage control signal S2 from the signal output unit 53 to each first variable resistor R1 or each second variable resistor R2 of the variable resistor group R, thereby changing the voltage value output by each first variable resistor R1 or each second variable resistor R2. The memory 52 of the control device 50 according to the fifth embodiment stores an applied voltage table 522. The control unit 51 acquires, for example, the liquid ejection speed (amount of liquid ejected per unit time) of each nozzle 80. The control unit 51 refers to the applied voltage table 522 and outputs a voltage control signal S2 to each of the first variable resistors R1 or each of the second variable resistors R2 to apply a voltage according to the liquid ejection speed of the nozzles 80.

[0069] The first variable resistor R1(k) is provided between the first active unit 88(k) and second switch 92(k) associated with the kth nozzle 80(k) and the main power supply (VCOM). That is, the first variable resistor R1(k) changes the voltage (VCOM voltage) that the main power supply (VCOM) applies to the first electrode 86 or the second electrode 85 of the kth nozzle 80(k) based on the voltage control signal S2.

[0070] The second variable resistor R2(k) is provided between the second active section 89(k) associated with the kth nozzle 80(k) and the sub-power supply (SCOM). That is, the second variable resistor R2(k) changes the voltage (SCOM voltage) that the sub-power supply (SCOM) applies to the second electrode 85 of the kth nozzle 80(k) based on the voltage control signal S2.

[0071] 16 is an explanatory diagram showing an example of the applied voltage table 522. The applied voltage table 522 stores the VCOM voltage that is changed by the first variable resistor R1 or the SCOM voltage that is changed by the second variable resistor R2 according to the rank of the liquid ejection speed of the nozzle 80. The rank is determined by the ejection speed of the liquid (ink) ejected from each nozzle 80. For example, five speed ranges are set for the liquid ejection speed, and the speed ranges correspond to ranks 1 to 5, respectively. The management items (fields) of the voltage application table include, for example, a liquid ejection speed field, a VCOM voltage field, and a SCOM field.

[0072] The liquid ejection speed field stores the rank of the speed of liquid ejected by the nozzle 80. In this example, the higher the rank (the larger the rank number), the faster the speed of liquid ejected by the nozzle 80. The VCOM voltage field stores the VCOM voltage to which the first variable resistor R1 is changed according to the rank of the liquid ejection speed. The SCOM voltage field stores the SCOM voltage to which the second variable resistor R2 is changed according to the rank of the liquid ejection speed. When the rank of the liquid ejection speed is high, the VCOM voltage or SCOM voltage may be relatively low to indicate that the energy application element has a high sensitivity to the applied voltage. When the rank of the liquid ejection speed is low, the VCOM voltage or SCOM voltage must be relatively high to indicate that the energy application element has a low sensitivity to the applied voltage. In this embodiment, the ratio of the VCOM voltage to the SCOM voltage corresponding to each rank is 2:1, but this is not limited to this. If the ratio of the VCOM voltage to the SCOM voltage corresponding to each rank is not 2:1, the lengths of the time slots will be uneven, and the lengths of time slots (3k-2) and (3k+2) will be different from the lengths of time slots (3k-1) and (3k+1) (see FIG. 9). When control unit 51 changes the VCOM voltage or SCOM voltage applied to the energy application element associated with nozzle 80, it may determine the length of each time slot based on the changed VCOM voltage and SCOM voltage, and update the elapsed time field of switch control table 521 (see FIG. 4).

[0073] 17 is a flowchart showing an example of an applied voltage change process performed by the control unit 51 of the control device 50. The control unit 51 of the control device 50 acquires the liquid ejection speed of the nozzle 80 (S21). The printing device 1 includes, for example, a sensor (not shown) disposed near the nozzle 80 to measure the amount of liquid ejected by the nozzle 80, and the control unit 51 acquires the liquid ejection speed of the nozzle 80 based on the detected value of the sensor. The control unit 51 determines the VCOM voltage and SCOM voltage to be applied to the energy application element associated with each nozzle, referring to an applied voltage table 522 based on the rank of the acquired liquid ejection speed (S22). Note that the memory 52 may store a table indicating the rank of each nozzle 80 determined in accordance with a liquid ejection speed measured in advance, and the control unit 51 may determine the VCOM voltage and SCOM voltage to be applied to the energy application element associated with each nozzle, referring to the table and the applied voltage table 522. The control unit 51 outputs a voltage control signal S2 to the first variable resistor R1 and the second variable resistor R2 to change the voltage applied to the energy imparting element to the determined VCOM voltage or SCOM voltage (S23), and ends the process.

[0074] (Embodiment 6) The following description is based on the drawings showing a printing device 1 according to the sixth embodiment. Among the components according to the sixth embodiment, components similar to those according to the first embodiment are given the same reference numerals, and detailed description thereof will be omitted. When a printing process is performed in which a nozzle 80 ejects ink, the control unit 51 of the control device 50 according to the sixth embodiment charges the second activation unit 89 associated with another nozzle 80 with the electric charge discharged by the second activation unit 89 associated with the nozzle 80.

[0075] 18 is a time chart showing the relationship between the charging voltage of the active unit and switch control when ink is ejected from the nozzle 80 according to the sixth embodiment. In the example shown in FIG. 18, a case will be described in which the SCOM voltage is less than half the VCOM voltage. Furthermore, when ink is ejected from the nozzle 80, there are two time slots during which the charging voltage of the first active unit 88 is kept at the COM voltage and the charging voltage of the second active unit 89 is kept at the VCOM voltage, from the time the control unit 51 of the control device 50 starts to the time it finishes controlling the first switch 91, second switch 92, and third switch 93 associated with the nozzle 80. Note that there may be three or more time slots during which the first active unit 88 is kept at the COM voltage and the charging voltage of the second active unit 89 is kept at the VCOM voltage.

[0076] Until control of the first switch 91, second switch 92, and third switch 93 associated with the nozzle 80 begins, the first switch 91 and second switch 92 are off, and the third switch 93 is on. That is, the COM voltage is applied to the second electrode 85 (see FIG. 3). In this embodiment, the COM terminal is connected to ground, and the COM voltage is 0 V. Furthermore, the VCOM voltage is always applied to the first electrode 86, and the COM voltage is always applied to the third electrode 84. Therefore, until control of the first switch 91, second switch 92, and third switch 93 begins, the charging voltage of the first active unit 88 is the VCOM voltage, and the charging voltage of the second active unit 89 is the COM voltage.

[0077] When control of the first switch 91, second switch 92, and third switch 93 associated with the kth nozzle 80(k) begins, the first switch 91 is turned on and the third switch 93 is turned off in the first time slot (3k-2). That is, the SCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 discharges charge from one end, and the charging voltage of the first active unit 88 becomes the value obtained by subtracting the SCOM voltage from the VCOM voltage (VCOM voltage - SCOM voltage). Also, the second active unit 89 is charged from one end, and the charging voltage of the second active unit 89 becomes the SCOM voltage.

[0078] After control for the kth nozzle 80(k) begins, the second switch 92 is turned on and the first switch 91 is turned off in the second time slot (3k-1). That is, the VCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 discharges charge from one end, and the charging voltage of the first active unit 88 becomes the COM voltage (0 V). Also, the second active unit 89 stores charge from one end, and the charging voltage of the second active unit 89 becomes the VCOM voltage. In time slot (3k-1), if the first switch 91 for a nozzle 80 other than the kth nozzle 80(k) is turned on and the second active unit 89 is discharging charge from one end, the charge discharged by the second active unit 89 is stored in the second active unit 89(k) for the kth nozzle 80(k).

[0079] After control for the kth nozzle 80(k) begins, in the third time slot (3k), the switch is not switched, the charging voltage of the first active unit 88 remains at the COM voltage (0V), and the charging voltage of the second active unit 89 remains at the VCOM voltage.

[0080] After control for the kth nozzle 80(k) begins, the first switch 91 is turned on and the second switch 92 is turned off in the fourth time slot (3k+1). That is, the SCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 is charged from one end, and the charging voltage of the first active unit 88 becomes the value obtained by subtracting the SCOM voltage from the VCOM voltage (VCOM voltage - SCOM voltage). The second active unit 89 also discharges from one end, and the charging voltage of the second active unit 89 becomes the SCOM voltage. In time slot (3k+1), if the first switch 91 for a nozzle 80 other than the kth nozzle 80(k) is turned on and the second active unit 89 is charging from one end, the charge charged by the second active unit 89 is the charge discharged by the second active unit 89(k) for the kth nozzle 80(k).

[0081] After control for the kth nozzle 80(k) begins, in the fifth time slot (3k+2), the third switch 93 is turned on and the first switch 91 is turned off. That is, the COM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 is charged from one end, and the charging voltage of the first active unit 88 becomes the VCOM voltage. Also, the second active unit 89 is discharged from one end, and the charging voltage of the second active unit 89 becomes the COM voltage.

[0082] After control for the kth nozzle 80(k) begins, in the sixth time slot (3k+3), the switch is not switched, the charging voltage of the first active unit 88 remains at the VCOM voltage, and the charging voltage of the second active unit 89 remains at the COM voltage (0V).

[0083] After control for the kth nozzle 80(k) begins, the first switch 91 is turned on and the third switch 93 is turned off in the seventh time slot (3k+4). That is, the SCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 discharges electric charge from one end, and the charging voltage of the first active unit 88 becomes the value obtained by subtracting the SCOM voltage from the VCOM voltage (VCOM voltage - SCOM voltage). Also, the second active unit 89 is charged with electric charge from one end, and the charging voltage of the second active unit 89 becomes the SCOM voltage.

[0084] After control for the kth nozzle 80(k) begins, in the eighth time slot (3k+5), the second switch 92 is turned on and the first switch 91 is turned off. That is, the VCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 discharges charge from one end, and the charging voltage of the first active unit 88 becomes the COM voltage (0 V). Also, the second active unit 89 stores charge from one end, and the charging voltage of the second active unit 89 becomes the VCOM voltage. In time slot (3k−1), if the first switch 91 for a nozzle 80 other than the kth nozzle 80(k) is turned on and the second active unit 89 is discharging charge from one end, the charge discharged by the second active unit 89 is stored in the second active unit 89(k) for the kth nozzle 80(k).

[0085] After control for the kth nozzle 80(k) begins, in the 9th time slot (3k+6), the switch is not switched, the charging voltage of the first active unit 88 remains at the COM voltage (0V), and the charging voltage of the second active unit 89 remains at the VCOM voltage.

[0086] After control for the kth nozzle 80(k) begins, the first switch 91 is turned on and the second switch 92 is turned off in the tenth time slot (3k+7). That is, the SCOM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 is charged from one end, and the charging voltage of the first active unit 88 becomes the value obtained by subtracting the SCOM voltage from the VCOM voltage (VCOM voltage - SCOM voltage). The second active unit 89 also discharges from one end, and the charging voltage of the second active unit 89 becomes the SCOM voltage. In time slot (3k+7), if the first switch 91 for a nozzle 80 other than the kth nozzle 80(k) is turned on and the second active unit 89 is charging from one end, the charge charged by the second active unit 89 is the charge discharged by the second active unit 89(k) for the kth nozzle 80(k).

[0087] After control for the kth nozzle 80(k) begins, in the 11th time slot (3k+8), the third switch 93 is turned on and the first switch 91 is turned off. That is, the COM voltage is applied to the second electrode 85 (see FIG. 3). As a result, the first active unit 88 is charged from one end, and the charging voltage of the first active unit 88 becomes the VCOM voltage. Also, the second active unit 89 is discharged from one end, and the charging voltage of the second active unit 89 becomes the COM voltage.

[0088] After control for the kth nozzle 80(k) begins, in the 12th time slot (3k+9), the switch is not switched, the charging voltage of the first active unit 88 remains at the VCOM voltage, and the charging voltage of the second active unit 89 remains at the COM voltage (0V).

[0089] In this embodiment, from the time when the control unit 51 of the control device 50 starts to control the first switch 91, the second switch 92, and the third switch 93 associated with the nozzle 80 to the time when it finishes, the length of the first time slot (3k) during which the charging voltage of the first activator 88 is kept at the COM voltage and the charging voltage of the second activator 89 is kept at the VCOM voltage is different from the length of the last time slot (3k+6). In this embodiment, the length of the first time slot (3k) during which the charging voltage of the first activator 88 is kept at the COM voltage and the charging voltage of the second activator 89 is kept at the VCOM voltage is longer than the length of the last time slot (3k+6), but they may be the same length or may be shorter than the length of the last time slot (3k+6).

[0090] FIG. 19 is an explanatory diagram showing changes in the value of the current flowing through the second electrode 85. FIG. 19 shows changes in the value of the current flowing through the second electrode 85 when the sub-power supply is not connected to the second electrode 85 via the first switch 91 in the voltage application circuit and when the sub-power supply is connected to the second electrode 85 via the first switch 91. When the sub-power supply is not connected, the control unit 51 of the control device 50 starts controlling the second switch 92 and the third switch 93 associated with the nozzle 80. The third switch 93, which had been turned on, is turned off, and the second switch 92, which had been turned off, is turned on. This switches the voltage applied to the second electrode 85 from the COM voltage to the VCOM voltage. A current flows through the second electrode 85 until the charging voltage of the second active unit 89 becomes the VCOM voltage. When the charging voltage of the second active unit 89 becomes the VCOM voltage, the current flowing through the second electrode 85 stops.

[0091] On the other hand, when a sub-power supply is connected to the second electrode 85, the control unit 51 of the control device 50 starts controlling the first switch 91, the second switch 92, and the third switch 93 associated with the nozzle 80. The third switch 93, which had been turned on, is switched off, and the first switch 91, which had been turned off, is switched on. This switches the voltage applied to the second electrode 85 from the COM voltage to the SCOM voltage. A current flows through the second electrode 85 until the charging voltage of the second active unit 89 reaches the SCOM voltage. Once the charging voltage of the second active unit 89 reaches the SCOM voltage, the current flowing through the second electrode 85 stops. The first switch 91, which had been turned on, is then switched off, and the second switch 92, which had been turned off, is switched on. This switches the voltage applied to the second electrode 85 from the SCOM voltage to the VCOM voltage. Current flows through the second electrode 85 until the charging voltage of the second active unit 89 reaches the VCOM voltage. When the charging voltage of the second active unit 89 reaches the VCOM voltage, the current stops flowing through the second electrode 85. The difference between the COM voltage and the SCOM voltage and the difference between the SCOM voltage and the VCOM voltage are smaller than the difference between the COM voltage and the VCOM voltage. Therefore, the peak current value of the second electrode 85 when the sub-power supply is connected is smaller than the peak current value of the second electrode 85 when the sub-power supply is not connected. Therefore, when the sub-power supply is connected during printing, the amount of heat generated by the second electrode 85 can be reduced, and the viscosity of the liquid (ink) ejected from the nozzle 80 can be stabilized. In other words, connecting the sub-power supply to the second electrode 85 can improve print quality.

[0092] FIG. 20 is an explanatory diagram showing changes in the voltage value applied to the second electrode 85. FIG. 20 shows changes in the voltage value applied to the second electrode 85 when the sub-power supply is not connected to the second electrode 85 via the first switch 91 in the voltage application circuit and when the sub-power supply is connected to the second electrode 85 via the first switch 91. When the sub-power supply is not connected, when the control unit 51 of the control device 50 starts controlling the second switch 92 and the third switch 93 associated with the nozzle 80, the third switch 93, which had been turned on, is switched off, and the second switch 92, which had been turned off, is switched on. This switches the voltage applied to the second electrode 85 from the COM voltage to the VCOM voltage. Note that it takes a time corresponding to the time constant from when the third switch 93, which had been turned on, is switched off and the second switch 92, which had been turned off, is turned on until the voltage applied to the second electrode 85 rises to the VCOM voltage.

[0093] On the other hand, when a sub-power supply is connected to the second electrode 85, the control unit 51 of the control device 50 starts controlling the first switch 91, the second switch 92, and the third switch 93 associated with the nozzle 80. The third switch 93, which had been turned on, is switched off, and the first switch 91, which had been turned off, is switched on. This switches the voltage applied to the second electrode 85 from the COM voltage to the SCOM voltage. When the voltage value applied to the second electrode 85 rises to the SCOM voltage, the first switch 91, which had been turned on, is switched off, and the second switch 92, which had been turned off, is switched on. This switches the voltage applied to the second electrode 85 from the SCOM voltage to the VCOM voltage, and the voltage value applied to the second electrode 85 rises to the VCOM voltage. When a sub-power supply is connected to the second electrode 85, a voltage with a small time constant is applied to the second electrode 85 twice. As a result, during printing, when the sub-power supply is connected, the time it takes from the start of voltage application to the second electrode 85 until the voltage value of the applied voltage rises to the VCOM voltage is shorter than the time it takes from the start of voltage application to the second electrode 85 until the voltage value of the applied voltage rises to the VCOM voltage when the sub-power supply is not connected. The same is true when the voltage value applied to the second electrode 85 is reduced from the VCOM voltage to the COM voltage. In other words, by connecting the sub-power supply to the second electrode 85, it is possible to reduce the rise and fall time constants of the ejection waveform that ejects liquid from the nozzles 80, increase the reproducibility of the ejection waveform, and improve print quality.

[0094] (Variation) In each of the above-described embodiments, the voltage application circuit does not necessarily have to include a sub-power supply. Fig. 21 is an explanatory diagram showing a configuration example of a voltage application circuit according to a modified example. Each second electrode 85 according to the modified example is connected to a second capacitor C2 via each first switch 91(1). At this time, the second capacitor C2 applies a SCOM voltage to each second electrode 85 by discharging its electric charge.

[0095] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The technical features described in each embodiment may be combined with one another, and the scope of the present invention is intended to include all modifications within the scope of the claims and equivalents thereto. Furthermore, independent and dependent claims described in the claims may be combined with one another in any and all combinations, regardless of the reference format. Furthermore, while the claims use a format in which a claim references two or more other claims (multiple claim format), this is not limiting. Multiple claims (multiple multiple claims) that reference at least one other multiple claim may also be used. [Explanation of symbols]

[0096] 1 Printing device 8 Inkjet head 9 Switches 50 Control device 51 Control section 52 memory 53 Signal output section 80 nozzles 81 Pressure Chamber 82 Diaphragm 83 Piezoelectric 84 3rd electrode 85 2nd electrode 86 1st electrode 87 Nozzle Plate 88 1st active part 89 2nd active part 91 First Switch 92 Second Switch 93 Third Switch 100 External device 501 Recording media 521 Switch Control Table 522 Applied Voltage Table C1 First capacitor C2 Second capacitor R variable resistor group R1 First variable resistor R2 Second variable resistor S1 Switch control signal S2 voltage control signal

Claims

1. a head including an energy imparting element and a nozzle that ejects liquid by the energy imparting element; a voltage application circuit that applies a voltage to the energy application element; A printing device comprising: The energy application element is a piezoelectric body in which a plurality of piezoelectric layers are stacked in a stacking direction, the piezoelectric body including: a first electrode formed on a first surface extending in an orthogonal direction perpendicular to the stacking direction; a second electrode provided at a position different from the first surface in the stacking direction and formed on a second surface extending in the orthogonal direction; and a third electrode provided at a position different from the first surface and the second surface in the stacking direction and formed on a third surface extending in the orthogonal direction; Equipped with The piezoelectric body is a first active portion sandwiched between the first electrode and the second electrode in the stacking direction; a second active portion sandwiched between the second electrode and the third electrode in the stacking direction; Equipped with The voltage application circuit includes: a first charging body connected to the first electrode or a second charging body connected to the second electrode; Printing device.

2. The voltage application circuit includes: a main power supply connected to the first electrode and the second electrode; a sub-power source connected to the second electrode; a first switch that switches between electrical connection and disconnection between the sub-power source and the second charger and the second electrode; a second switch that switches between electrical connection and non-connection between the main power supply and the second electrode; Equipped with The voltage value output by the sub-power supply is lower than the voltage value output by the main power supply. The printing device of claim 1 .

3. The head A first nozzle; a first pressure chamber connected to the first nozzle; A second nozzle; a second pressure chamber connected to the second nozzle; Equipped with The piezoelectric body is the first active portion overlapping the first pressure chamber in the stacking direction; the second active portion overlapping the first pressure chamber in the stacking direction; the first active portion overlapping the second pressure chamber in the stacking direction; the second active portion overlapping the second pressure chamber in the stacking direction; Equipped with the voltage application circuit includes the first charging body, the main power supply is connected to the first electrodes associated with the plurality of nozzles, the main power supply is connected to the second electrodes associated with the plurality of nozzles via the second switches, the sub-power supply is connected to the second electrode associated with each of the plurality of nozzles via the first switch; The first charge body is the first active portion that overlaps with the first pressure chamber in the stacking direction. The printing device according to claim 2 .

4. the voltage application circuit includes the first charging body, The first charge body is a first capacitor connected in parallel to the main power supply. The printing device according to claim 2 .

5. The head A first nozzle; a first pressure chamber connected to the first nozzle; A second nozzle; a second pressure chamber connected to the second nozzle; Equipped with The piezoelectric body is the first active portion overlapping the first pressure chamber in the stacking direction; the second active portion overlapping the first pressure chamber in the stacking direction; the first active portion overlapping the second pressure chamber in the stacking direction; the second active portion overlapping the second pressure chamber in the stacking direction; Equipped with the voltage application circuit includes the second charging body, the main power supply is connected to the first electrodes associated with the plurality of nozzles, the main power supply is connected to the second electrodes associated with the plurality of nozzles via the second switches, the sub-power supply is connected to the second electrode associated with each of the plurality of nozzles via the first switch; The second charge body is the second active portion that overlaps with the second pressure chamber in the stacking direction. The printing device according to claim 2 .

6. the voltage application circuit includes the second charging body, The second charge body is a second capacitor connected in parallel to the sub-power supply. The printing device according to claim 2 .

7. the second electrode is connected to ground; a third switch that switches between electrical connection and non-connection between the second electrode and the ground; Control unit and Equipped with The control unit performing on / off control of the first switch, the second switch, and the third switch to switch between electrical connection and non-connection; Furthermore, From a state in which only the third switch among the first switch, the second switch, and the third switch is on, Turning the third switch off and the first switch on; Turning the first switch off and the second switch on; Switching the second switch off and the first switch on; The first switch is turned off and the third switch is turned on. Execute the on / off control The printing device according to any one of claims 3 to 6.

8. The control unit performs the on / off control when a non-ejection flushing process is performed in which the inside of the nozzle is vibrated. The printing device according to claim 7.

9. The control unit performs the on / off control when a printing process is performed in which liquid is ejected from the nozzles. The printing device according to claim 7.

10. The control unit Obtain the print data, Identifying the nozzles that do not eject liquid based on the print data; The on / off control is performed for the first switch, the second switch, and the third switch associated with the identified nozzle. The printing device according to claim 7.

11. Obtaining the status of the nozzle; The voltage output by the main power supply or the sub-power supply is changed according to the acquired state of the nozzle. The printing device according to claim 2 .

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