JP2019119171A - Droplet discharge device - Google Patents

Abstract

To provide a droplet discharge device in which life elongation of a head unit can be achieved.SOLUTION: A controller controls a selective circuit in such a manner that index value information, which represents a degree of deterioration of each driving element which constitutes a driving element group A, is acquired after detection of a prescribed momentum, each of driving elements, which constitute a driving element group B to which a power supply circuit B, which outputs a voltage lower than a voltage outputted by a power supply source A allocated to the driving element group A, is allocated, is connected to the power supply circuit B, each driving element, in which a value represented by said index value information is a first threshold or more, among plural driving elements which constitute the driving element group A is connected to a power supply circuit, which is different from the power supply circuit B and outputs a voltage lower than a voltage outputted by the power supply circuit A, or the power supply circuit B, each driving element, in which a value represented by said index value information is smaller than the first threshold, among plural driving elements which constitute the driving element group A is connected to the power supply circuit A.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a droplet discharge device.

  In Patent Document 1, in order to extend the life of the droplet discharge head, the number of droplet discharges is integrated for each nozzle, and when the integrated value exceeds a predetermined value, energy to be applied to the piezoelectric element is more than usual. A droplet discharge head is disclosed which is made smaller.

JP, 2011-168063, A

  However, the discharge speed of the droplets discharged by the piezoelectric element driven with small energy is slower than the speed of the droplets discharged by the other piezoelectric elements. In addition, the discharge amount of the droplets discharged by the piezoelectric element driven with small energy is smaller than the discharge amount of the droplets discharged by the other piezoelectric elements. Therefore, if the energy to be applied is reduced for all the piezoelectric elements whose integrated value of the number of times of ejection exceeds the predetermined value, the image quality of the printed image may be significantly deteriorated.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a droplet discharge device capable of prolonging the life of the droplet discharge device and forming an image of good image quality. .

  A droplet discharge device according to an embodiment of the present invention includes N nozzles, N drive elements provided corresponding to the N nozzles, and drive signals supplied to the respective drive elements. Between the M power circuits for generating M, the driving elements of the N driving elements and the M power circuits, and for each driving element of the N driving elements, A selection circuit for selectively connecting one of the M power supply circuits, and M drive element groups divided according to voltages of drive signals supplied to the N drive elements. The controller includes: a memory storing assignment information indicating a power supply circuit to be assigned to each drive element of each drive element group; and a controller, wherein the controller detects a predetermined timing and then detects one of the M drive element groups. Drive element group A Index value information indicating the value of the degree of deterioration of the drive element is acquired for each of the drive elements to be acquired, and the index value information is acquired, and then allocated to the drive element of the drive element group A in the allocation information Each of the drive elements constituting the drive element group B to which the power supply circuit B outputting a voltage lower than the voltage output from the power supply circuit A is connected is connected to the power supply circuit B, and the drive element group A is Each of the drive elements whose value indicated by the index value information is a first threshold or more among the plurality of drive elements to be configured is a power supply circuit different from the power supply circuit B from the voltage output from the power supply circuit A Is connected to the power supply circuit that outputs a low voltage or the power supply circuit B, and the index value information indicates among the plurality of drive elements that constitute the drive element group A. There and controls the selection circuit to the respective small drive element than the first threshold value, is connected to the power supply circuit A.

  According to the present invention, it is possible to extend the life of the droplet discharge device and to form an image of good image quality.

FIG. 2 is a plan view showing an example of the main configuration of the printing apparatus of the present embodiment. It is a top view which shows an example of a principal part structure at the time of seeing the inkjet head of this Embodiment from the nozzle surface side. It is a block diagram which shows an example of a structure of the 2nd board | substrate with which the head unit of this Embodiment is equipped, and the flexible circuit board connected with the 2nd board | substrate. An example of a circuit structure with which a driver IC is provided is shown. It is a circuit diagram showing an example of composition of a waveform generation circuit with which a head unit of this embodiment is provided. FIG. 6 is an explanatory view showing an example of voltage setting in an initial state of the head unit of the present embodiment and power allocation in the initial state. It is explanatory drawing which shows the rule of the change of the power supply allocation in this Embodiment. It is a flowchart which shows an example of the process sequence by the head unit of this Embodiment. It is a flowchart which shows an example of the process sequence of the power supply setting by the head unit of this Embodiment. It is explanatory drawing which shows the other example of the rule of the change of the power supply allocation of the head unit of this Embodiment. It is an explanatory view showing an example of amendment of an output voltage by ink temperature of a head unit of this embodiment. It is an explanatory view showing an example of amendment of an output voltage by a characteristic of ink of a head unit of this embodiment. It is explanatory drawing which shows an example of the calculation method of the frequency | count of discharge of the droplet by the head unit of this Embodiment. It is explanatory drawing which shows an example of the log information updated by FIG.8 S16. It is a schematic block diagram of 2nd Example. It is an explanatory view showing assignment of a drive signal generation circuit of an initial state. It is explanatory drawing which shows the rule of a change of allocation of the drive signal generation circuit in 2nd Example. It is a flowchart which shows an example of the process sequence by the droplet discharge apparatus of 2nd Example. It is a flowchart which shows an example of the process sequence of the setting of the drive signal generation circuit by the droplet discharge apparatus of 2nd Example.

First Embodiment
Hereinafter, a first embodiment will be described based on the drawings. FIG. 1 is a plan view showing an example of the main configuration of a printing apparatus 1 according to the present embodiment. The printing apparatus 1 is, for example, an inkjet printer. In addition, as shown in FIG. 1, in the present specification, for the sake of convenience, each direction of front, rear, left, and right will be described as a direction indicated by an arrow. The printing apparatus 1 includes a housing 2.

  The housing 2 is provided with a platen 3, four inkjet heads 4, transport rollers 5 and 6, a control device 7 and the like. The numbers of the inkjet head 4 and the conveyance rollers 5 and 6 are not limited to the example shown in FIG.

  In addition, a plurality of head holders 8 are attached to the housing 2. The plurality of head holding portions 8 are arranged in parallel along the front-rear direction at a position above the platen 3 and between the two conveyance rollers 5 and 6. The head holding unit 8 holds the ink jet heads 4 respectively.

  The recording paper 100 used by the printing apparatus 1 is placed on the platen 3. The transport rollers 5 and 6 are disposed at both ends in the front-rear direction of the platen 3, and the recording paper 100 is transported along the front-rear direction (transport direction) by rotation of the transport rollers 5 and 6.

  The inkjet head 4 has a rectangular outer shape in plan view. The inkjet head 4 is arranged such that the transport direction (front-rear direction) in which the recording paper 100 is transported is short, and the direction (left-right direction) orthogonal to the transport direction is longitudinal. The inkjet head 4 is disposed such that the nozzle surface of the inkjet head faces the platen 3. The four inkjet heads 4 are arranged between the transport rollers 5 and 6 along the front-rear direction.

  The four inkjet heads 4 correspond to, for example, cyan, magenta, yellow, and black.

  The control device 7 includes a first substrate 71 described later. The inkjet head 4 includes a head unit 11 as a plurality of droplet discharge devices. Further, the head unit 11 includes a second substrate 50 described later and a flexible circuit substrate 60 described later. The flexible circuit board 60 is connected to the second substrate 50. That is, one second substrate 50 and one flexible circuit board 60 are provided corresponding to one head unit 11, respectively. For example, when the printing apparatus 1 includes four inkjet heads 4 and each inkjet head 4 includes nine head units 11, the printing apparatus 1 includes thirty-six head units 11, the second substrate 50 The number of the flexible circuit boards 60 connected to the second substrate 50 is thirty six. The first substrate 71 is connected to the 36 second substrates 50.

  The control device 7 operates a motor (not shown) to control the operation of the transport rollers 5 and 6 to transport the recording paper 100. When an instruction for printing by the user is input through the operation unit of the external device 9 or the printing apparatus 1, the control device 7 outputs a signal of the printing instruction, raster data of the image to be printed, etc. Send to Then, the control device 7 causes the head unit 11 of each inkjet head 4 to discharge the ink onto the recording paper 100 while the recording paper 100 is being transported.

  Further, the control device 7 can mutually communicate with an external device 9 such as a personal computer. The control device 7 controls the operations of the inkjet heads 4 and the conveyance rollers 5 and 6 according to a program stored in the ROM according to an instruction from an operation unit (not shown) of the external device 9 or the printing device 1. Note that a CPU (central processing unit) or an MPU (microprocessor unit) may be used instead of the FPGA 711.

  The first substrate 71 is provided with a ROM (Read Only Memory), a RAM (Random Access Memory), a non-volatile memory 712, etc., in addition to an FPGA (Field Programmable Gate Array) 711. The nonvolatile memory 712 may be an EEPROM (Electrically Erasable Programmable Read-Only Memory) or the like.

  FIG. 2 is a plan view showing an example of the main configuration when the inkjet head 4 of the present embodiment is viewed from the nozzle surface side. The head units 11 are arranged in two rows in the front-rear direction. In the front row 82, four head units 11 are arranged in the left-right direction, and in the rear row 81, five head units 11 are arranged in the left-right direction. On the nozzle surface of the head unit 11 (the lower surface of the nozzle plate), discharge ports (openings) 11a of a plurality of nozzles are provided. Further, the head unit 11 is provided with driving elements 111 (described later) in the same number as the ejection openings 11 a of the nozzles. The discharge ports 11 a of the nozzles are schematically represented for the sake of convenience, and are different from the actual arrangement and number. Further, in the example of FIG. 2, the inkjet head 4 is configured to include nine head units 11, but the number of head units 11 is not limited to nine. Each head unit 11 includes a second substrate 50 described later, a flexible circuit board 60, and the like.

  FIG. 3 is a block diagram showing an example of the configuration of the second substrate 50 provided in the head unit 11 of the present embodiment and the flexible circuit board 60 connected to the second substrate 50. As shown in FIG. In FIG. 3, one second substrate 50 and one flexible circuit board 60 are illustrated.

  The second substrate 50 includes an FPGA 51 as a controller, a non-volatile memory 52 such as an EEPROM, a DRAM 53 for temporarily storing raster data received from the control device 7, a D / A converter 20, a power supply circuit 21, a power supply circuit 22, and a power supply A circuit 23, a power supply circuit 24, a power supply circuit 25, a power supply circuit 26, and the like are provided. The flexible circuit board 60 further includes a nonvolatile memory 62 such as an EEPROM, a driver IC 27, a temperature sensor 190 for detecting the temperature of ink, and the like. Note that a CPU (Central Processing Unit) or MPU (Microprocessor Unit) may be used instead of the FPGA 51.

  The FPGA 51 outputs a setting signal for setting the output voltage of the power supply circuit 21 to the power supply circuit 26 to the D / A converter 20. The FPGA 711 controls the output of the setting signal by the FPGA 51. The setting signal is a digital signal.

  The D / A converter 20 converts the digital setting signal output from the FPGA 51 into an analog setting signal and outputs the analog setting signal to the power supply circuits 21 to 26.

  The power supply circuit 21 to the power supply circuit 26 can be, for example, a DC / DC converter including a plurality of electronic components such as an FET, an inductor, a resistor, and an electrolytic capacitor. Each of the power supply circuits 21 to 26 outputs the output voltage designated by the setting signal to the driver IC 27.

  The power supply circuit 21 is connected to the driver IC 27 through the wiring VDD1. The power supply circuit 22 is connected to the driver IC 27 through the wiring VDD2. The power supply circuit 23 is connected to the driver IC 27 through the wiring VDD3. The power supply circuit 24 is connected to the driver IC 27 via the wiring VDD4. The power supply circuit 25 is connected to the driver IC 27 through the wiring VDD5. The power supply circuit 26 is connected to the driver IC 27 through the wiring HVDD. The power supply circuit 26 is connected to a drive element 111 described later via a wiring VCOM. The wiring HVDD and the wiring VCOM are obtained by dividing the wiring drawn from the power supply circuit 26 into two wirings in the middle of the path.

  The power supply circuit 21 to the power supply circuit 26 are a waveform generation circuit 30 (1) to a waveform generation circuit 30 (n) (n is a natural number of 2 or more) formed inside the driver IC 27. (Each equal to the number of elements 111). Details of the driver IC 27 will be described later.

  The power supply circuits 21 to 25 are power supply circuits used normally. The power supply circuit 26 is a power supply circuit of a special specification. The power supply circuit 26 can be used in combination as a VCOM power supply voltage of the drive element 111 or as HVDD (high side bag gate voltage) of PMOS transistors 311 to 315 described later.

  The driver IC 27 is connected to the FPGA 51 through n control lines 33 (1) to (n) and a control line 40. Further, the driver IC 27 is connected to n driving elements 111 via n signal lines 34 (1) to (n). Each signal line 34 is connected to an individual electrode of the drive element. Further, the driver IC 27 is connected to a wiring GND which is a ground line.

  The control lines 33 (1) to 33 (n) are control lines provided corresponding to the n waveform generation circuits 30 (1) to 30 (n) described above. A signal for controlling the FET provided in each waveform generation circuit 30 is propagated to each control line 33. In accordance with this signal, the waveform generation circuit 30 of the driver IC 27 generates a drive signal for driving the drive element 111, and outputs the generated drive signal to the drive element 111 via the signal line. The printing apparatus 1 according to the present embodiment is provided with three types of drive signals corresponding to droplets of three different sizes of large balls, middle balls, and small balls as drive signals for discharging droplets from the nozzles. ing. The three types of drive signals have different waveforms. The waveform generation circuit 30 generates different types of drive signals in accordance with the signal propagated to the control line 33.

  A control signal for controlling n selectors 90 (1) to (n), which will be described later, included in the driver IC 27 is transmitted to the control line 40. The FPGA 51 controls the n selectors 90 (1) to (n) to select a power supply circuit for generating a drive signal to be output to each signal line 34.

  FIG. 4 shows an example of the circuit configuration of the driver IC 27. The driver IC 27 includes n selectors 90 (1) to (n) provided corresponding to the n waveform generation circuits 30 (1) to (n) and the respective waveform generation circuits 30 (1) to (n). ). The n selectors 90 (1) to (n) are provided corresponding to the n driving elements 111. Each selector 90 is a component of hardware configured of a plurality of FETs and the like formed inside the driver IC 27. The n selectors 90 (1) to (n) included in the driver IC 27 are an example of a selection circuit.

  The driver IC 27 has the same configuration as the number n of nozzles equal to the number of nozzles, and therefore, the driver IC 27 is provided between the control line 33 (1) and the signal line 34 (1) as a representative below. The circuit configuration will be described. In the driver IC 27, the selector 90 (1) and the waveform generation circuit 30 (1) are formed between the control line 33 (1) and the signal line 34 (1).

  The control line 33 (1) from the FPGA 51 is connected to the selector 90 (1). The control line 33 (1) branches in the middle of the path connecting the FPGA 51 and the selector 90 (1), and the control line SB (1) branched in the middle from the control line 33 (1) has the waveform generation circuit 30 (1). Connected with).

  Selector 90 (1) and waveform generation circuit 30 (1) are connected by five control lines S1 (1), S2 (1), S3 (1), S4 (1), and S5 (1). ing. The selector 90 (1) is selected from among five control lines S1 (1), S2 (1), S3 (1), S4 (1), and S5 (1) according to an instruction from the FPGA 51. One control line is connected to the control line 33 (1).

  Further, to the waveform generation circuit 30 (1), the five wirings connected to the wirings VDD1 to 5 described above, the wirings connected to the wiring HVDD, and the wirings connected to the wiring GND are connected.

  FIG. 5 is a circuit diagram showing an example of the configuration of the waveform generation circuit 30 (1) provided in the head unit 11 of the present embodiment. Since the waveform generation circuits 30 (1) to 30 (n) have the same configuration, FIG. 5 describes the waveform generation circuit 30 (1). The waveform generation circuit 30 (1) includes five PMOS (P-type Metal Oxide Semiconductor) transistors 311 to 315 (only two are shown in FIG. 5), one NMOS (N-type Metal Oxide Semiconductor) transistor 32, and a resistor. And 35 etc. The waveform generation circuit 30 (1) is connected to the individual electrodes of the drive element 111 via the signal line 34 (1).

  The driving element 111 of the present embodiment is a piezoelectric element as disclosed in FIG. 5 of Japanese Patent Application Laid-Open No. 2015-24531 (Japanese Patent Application No. 2013-154357). The driving element 111 is a piezoelectric element including a first active portion sandwiched between an individual electrode and a first constant potential electrode, and a second active portion sandwiched between an individual electrode and a second constant potential electrode. It is. For this reason, the drive element 111 includes a capacitor 111b and a capacitor 111b '.

  Five source terminals 311 a to 315 a of five PMOS transistors 311 to 315 are connected to the signal line 34 (1). The source terminal 32a of the NMOS transistor 32 is connected to the ground. In FIG. 5, the PMOS transistors 312 to 314 are omitted.

  Further, a control line S1 (1) is connected to the gate terminal 311c of the PMOS transistor 311. A control line S2 (1) is connected to the gate terminal 312c of the PMOS transistor 312. A control line S3 (1) is connected to the gate terminal 313c of the PMOS transistor 313. A control line S4 (1) is connected to the gate terminal 314c of the PMOS transistor 314. A control line S5 (1) is connected to the gate terminal 315c of the PMOS transistor 315. Further, a control line SB (1) is connected to the gate terminal 32c of the NMOS transistor 32.

  Further, the PMOS transistor 311 is connected to the power supply circuit 21 through the wiring VDD1. The PMOS transistor 312 is connected to the power supply circuit 22 through the wiring VDD2. The PMOS transistor 313 is connected to the power supply circuit 23 through the wiring VDD3. The PMOS transistor 314 is connected to the power supply circuit 24 through the wiring VDD4. The PMOS transistor 315 is connected to the power supply circuit 25 through the wiring VDD5.

  The drain terminals 311 b to 315 b of the five PMOS transistors 311 to 315 are connected to one end of the resistor 35. The drain terminal 32 b of the NMOS transistor 32 is connected to one end of the resistor 35. The other end of the resistor 35 is connected to an individual electrode of the drive element 111 (the other end of the capacitor 111 b ′ and one end of the capacitor 111 b). The first constant potential electrode (one end of the capacitor 111b ') of the drive element 111 is connected to VCOM, and the second constant potential electrode (the other end of the capacitor 111b) of the drive element 111 is connected to the ground.

  When the FPGA 51 outputs a low level ("L") signal to the control line 33 (1), any one of the PMOS transistors 311 to 315 connected to the signal line selected by the selector 90 (1) described above. The PMOS transistor is turned on. The capacitor 111b is charged by the voltage supplied from any one of the power supply circuits 21 to 25, and the capacitor 111b 'is discharged. On the other hand, when the FPGA 51 outputs a high level ("H") signal to the control line 33 (1), the NMOS transistor 32 is turned on, and the voltage output from any one of the power supply circuits 21 to 25 Thus, the capacitor 111b 'is charged and the capacitor 111b is discharged. By alternately charging and discharging the capacitors 111b and 111b ', the drive element 111 is deformed, and the ink is discharged from the discharge port 11a of the nozzle.

  That is, a drive signal for driving the drive element 111 is output to the signal line 34 (1). The selector 90 (1) selects one of the five control lines S1 (1) to S5 (1) to be connected to the control line to select one of the five power supply circuits for generating a drive signal. It can be selected from 21-25.

  Next, the operation of the head unit 11 of the present embodiment will be described.

  When a predetermined voltage is applied to the drive element 111, the discharge speed and discharge amount of the liquid droplets discharged from the discharge port 11a vary among the nozzles. The nozzle having a slow discharge speed has a small discharge amount, and the nozzle having a high discharge speed has a large discharge amount. Therefore, in the head unit 11 according to the present embodiment, the plurality of drive elements 111 corresponding to each nozzle are divided into, for example, five drive element groups, from high to low droplet discharge speed, for example. The power supply circuit 21 to the power supply circuit 25 are assigned to each section.

  A power supply circuit with a low output voltage is assigned to the drive element 111 forming a drive element group having a high discharge speed, and a power supply circuit having a high output voltage is provided to the drive element 111 forming a drive element group with a low discharge speed. assign. As a result, it is possible to print high-quality images by reducing the variation in discharge speed and discharge amount for each nozzle.

  However, when the drive element 111 to which the power supply circuit having a high output voltage is assigned is driven at a high frequency, deterioration of the drive element 111 is promoted compared to the other drive elements 111, and the life becomes extremely short. Therefore, in the present embodiment, among the drive elements 111 to which the power supply circuit having a high output voltage is assigned, the power supply circuit to be assigned to the drive element 111 having a large number of ejections in the printing operation to be performed is assigned in the initial state. By changing to another power supply circuit that outputs an output voltage lower than that of the power supply circuit, it is possible to prevent the deterioration of the drive element from being accelerated.

  FIG. 6 is an explanatory view showing an example of voltage setting in the initial state of the head unit 11 of the present embodiment and power allocation in the initial state. The upper part of FIG. 6 is an explanatory view showing voltage setting in the initial state. The power supply 1 to the power supply 5 in FIG. 6 represent the power supply circuit 21 to the power supply circuit 25 for the sake of convenience. Also in the following description, the power supply circuits 21 to 25 may be described as the power supplies 1 to 5. The output voltages of the power supplies 1 to 5 are set to, for example, 26.5 V, 25.9 V, 25.1 V, 24.4 V, and 23.6 V. As described above, the voltage value of the output voltage corresponding to each of the power supply circuits 21 to 25 is set in advance, and the information on the voltage setting in this initial state is stored in advance in the non-volatile memory 62.

  Further, the lower part of FIG. 6 is an explanatory view showing an example of the power allocation in the initial state. The drive element number is an identification number for identifying 1680 drive elements. As shown in the lower part of FIG. 6, the power supply connected to each drive element is set in advance, and the information of the power supply allocation in this initial state is stored in advance in the non-volatile memory 62. In the following description, a group including the drive elements 111 to which the power supply 1 is assigned in the initial state is referred to as a drive element group 1. A group formed of drive elements 111 to which the power supply 2 is assigned in the initial state is referred to as a drive element group 2. A group formed of drive elements 111 to which the power supply 3 is assigned in the initial state is referred to as a drive element group 3. A group including drive elements to which the power supply 4 is assigned in the initial state is referred to as a drive element group 4. A group including drive elements to which the power supply 5 is assigned in the initial state is referred to as a drive element group 5. In the lower part of FIG. 6, power sources 2, 2, 1, 3,..., 5 are assigned to the driving element numbers 1, 2, 3, 4,. In the case where the driving element group is divided into five driving element groups in accordance with the ejection speed, each driving element group is configured of a plurality of driving elements 111.

  FIG. 7 is an explanatory view showing a rule of changing power supply allocation in the present embodiment. In the present embodiment, the number of times of discharge of droplets by each drive element 111 in the printing operation to be performed from now is obtained, and the printing operation is performed in a state where the power supply allocation is reviewed. FIG. 7 shows how the power supply 1 to the power supply 5 assigned to each drive element 111 of each drive element group are changed according to the number of times of ejection. For example, the drive element group 1 to which the power supply 1 is assigned in the initial state is changed as follows. The power supply 1 is assigned to the driving element 111 whose ejection frequency is smaller than the first threshold (for example, 10,000 times) without changing from the initial state. On the other hand, the power supply 2 is allocated to the driving element 111 whose number of ejections is equal to or more than the first threshold and smaller than the second threshold (for example, 15,000 times). Further, the power supply 3 is assigned to the driving element 111 whose number of ejections is equal to or more than a second threshold (for example, 15,000 times). The driving element group 2 to which the power supply 2 is assigned in the initial state is changed as follows. The power supply 2 is allocated to the drive element whose ejection frequency is smaller than the second threshold (for example, 15,000 times) as in the initial state. On the other hand, the power supply 3 is assigned to the drive element 111 whose ejection frequency is smaller than the second threshold (for example, 15,000 times). Further, for the drive element groups 3 to 5 to which the power supplies 3 to 5 are allocated in the initial state, the change of the power supply allocation is not performed regardless of the number of times of ejection. That is, even after reviewing the power allocation, the same power as in the initial state is allocated. Rules for changing the power supply assignment as shown in FIG. 7 are stored in advance in the non-volatile memory 62. The number of times the droplet is discharged by the driving element 111 can be calculated, for example, from raster data. Details of the method of calculating the number of times of ejection will be described later.

  FIG. 8 is a flow chart showing an example of the processing procedure by the head unit 11 of the present embodiment. The process illustrated in FIG. 8 is started by, for example, the FPGA 51 when the power of the printing apparatus 1 is turned on. First, the FPGA 51 determines whether to start printing (S10). Whether to start printing is determined based on whether or not an instruction to start printing has been received from the control device 7. When the user issues a print instruction by the user via the operation unit of the above-described external device 9 or printing device 1, the control device 7 prints information indicating that there is an unprocessed print job and the print job The non-volatile memory 712 stores the image data of the image to be printed and the information for identifying the print mode at the time of executing the print job. The print mode can be designated by the user via the operation unit of the external device 9 or the printing device 1 described above. Then, when the non-volatile memory 712 stores that there is an unprocessed print job, the control device 7 transmits a print start instruction to the FPGA 51. When the FPGA 51 receives an instruction to start printing from the control device 7, the FPGA 51 determines that printing is to be started. That is, the FPGA 51 can determine that printing is to be started when there is an unprocessed print job, and it can be determined that printing will not be started when there is no unprocessed print job. Further, the control device 7 creates raster data, which is a set of data for specifying the size of droplets to be ejected from each nozzle, based on the image data corresponding to the print job, and transmits the raster data to the FPGA 51. Print mode identification information identifying the print mode at the time of printing is sent to the FPGA 51. The print mode can be, for example, a high image quality mode and a normal mode. The control device 7 transmits raster data corresponding to each head unit 11 to each FPGA 51.

  If the FPGA 51 determines that the printing start instruction has not been received (NO in S10), the FPGA 51 determines whether the power-off operation of the printing apparatus 1 has been performed (S17). . When receiving an instruction to start printing from the control device 7 and determining to start printing (YES in S10), the FPGA 51 acquires the raster data described above and information identifying the print mode (S11). The FPGA 51 stores the acquired raster data in the DRAM 53, and stores the printing mode identification information in the non-volatile memory 52.

  Next, the FPGA 51 acquires the ink temperature from the temperature sensor 190, and stores the acquired ink temperature in the non-volatile memory 52 (S12).

  The FPGA 51 reads out the history information as shown in FIG. 14 and the power supply allocation information in the initial state shown in FIG. 6 from the non-volatile memory 62 (S13). The history information includes, for example, information on the total number of ejections of the droplets ejected by the driving elements 111 in the past printing operation. A detailed description of the history information will be described later. The FPGA 51 performs power supply setting processing (S14). The process of power setting will be described later.

  The FPGA 51 performs the printing operation in a state where the power setting is performed in step S14 (S15). Then, the FPGA 51 updates the history information stored in the non-volatile memory 62 by, for example, adding the number of droplet discharges by each driving element 111 during the printing operation this time to the total number of discharges of the history information. Perform (S16). The FPGA 51 determines whether the power off operation has been performed (S17). If the power OFF operation has not been performed (NO in S17), the process returns to S10 described above, and it is determined whether printing is to be started. If the power-off operation has been performed (YES in S17), the FPGA 51 ends the process.

  FIG. 9 is a flowchart showing an example of the processing procedure of power supply setting by the head unit 11 according to the present embodiment. The FPGA 51 determines whether there is a drive element 111 for which the total ejection number of history information stored in the nonvolatile memory 62 is equal to or more than a predetermined number (S101). Specifically, for each of all 1680 driving elements 111, for example, it is determined whether the total value of the number of times of droplet ejection is equal to or more than a predetermined number of times (for example, one million times).

  If there is a drive element 111 whose total number of ejections is equal to or greater than a predetermined number (YES in S101), that is, if the total number of ejections is equal to or greater than one of the 1680 drive elements 111, The FPGA 51 raises the output voltage of all the power supplies by a predetermined voltage (for example, 0.5 V) from the voltage set in the initial state (S102) and raises the predetermined voltage by a predetermined voltage as a voltage setting at the time of the printing operation to be performed Remember.

  Specifically, the output voltage of the power supply circuit 21 in which 26.5 V is set in the initial state is changed to 27.0 V, and the output voltage of the power supply circuit 22 in which 25.9 V is set in the initial state is changed to 26. The output voltage of the power supply circuit 23 which is changed to 4V and 25.1V in the initial state is changed to 25.6V, and the output voltage of the power supply circuit 24 which is set 24.4V in the initial state is 24. The output voltage of the power supply circuit 25 which is changed to 9 V and 23.6 V is set in the initial setting is changed to 24. 1 V. The information of the voltage setting thus changed is stored in the non-volatile memory 52. In the present embodiment, when there is only one drive element 111 having a total number of ejections equal to or more than a predetermined number, it is considered that the deterioration of the other drive elements 111 has progressed to some extent, and the output voltage to all the drive elements 111 is The voltage is raised by a predetermined voltage. As a result, the variation in image quality between the head unit 11 in which the drive element 111 has not been deteriorated and the head unit 11 in which the deterioration of the drive element 111 has generally progressed is reduced. be able to.

  After changing the voltage setting in step 102 described above, or when there is no drive element 111 whose total number of times of ejection is equal to or more than a predetermined number (NO in S101), the output of each power supply according to the ink temperature and the characteristics of the ink The voltage is corrected (S103).

  An example of the correction of the output voltage based on the ink temperature performed by the FPGA 51 in step S103 will be described with reference to FIG. Information indicating a correction coefficient corresponding to the ink temperature as shown in FIG. 11 is stored in advance in the non-volatile memory 62. In the example shown in FIG. 11, the temperature of the ink is divided into three sections: low (eg, less than 38 ° C.), normal (eg, 38 ° C. or more and less than 42 ° C.), and high (eg, 42 ° C. or more). Numerical values in FIG. 11 are correction coefficients for correcting the output voltage of each power supply. Correction coefficients corresponding to the three divisions of the ink temperature are stored for each of the power supplies 1 to 5. The correction coefficient is a coefficient for calculating the value of the output voltage after correction by multiplying the value of the output voltage determined by the voltage setting in the initial state or the voltage setting changed in step 102 described above. When the voltage setting in the initial state is changed in step 102 described above, a new output voltage value is calculated by multiplying the value of the output voltage determined by the changed voltage setting by the correction coefficient, and a new value is calculated. A value associated with each power source is stored in the non-volatile memory 52 as voltage setting at the time of printing operation. At this time, the FPGA 51 calculates the output voltage of each of the power supplies 1 to 5 using the correction coefficient corresponding to the ink temperature acquired in step S12 of FIG. For example, when the temperature detected by the temperature sensor 190 is 36 ° C., the output voltage of the power supplies 1 to 5 is corrected using the correction coefficient set as the correction coefficient when the ink temperature is low. The correction coefficient when the ink temperature is low is set to a value larger than 1.0 for each power supply. Therefore, when the viscosity of the ink is increased due to the low temperature of the ink and it becomes difficult to eject the ink, the output voltage can be increased. Since the correction coefficient when the ink temperature is normal is set to a value of 1.0 for each power supply, the output voltage is not changed. Therefore, even when it is difficult to eject the ink because the temperature of the ink is low, it is possible to eject a droplet having the same size as the droplet ejected when the temperature of the ink is in the normal temperature range. On the contrary, the correction coefficient when the ink temperature is high is set to a value smaller than 1.0. Therefore, when the viscosity of the ink is reduced due to the high temperature of the ink and the ink is easily ejected, the output voltage can be lowered. Therefore, even when the ink is easily ejected due to the high temperature of the ink, it is possible to eject droplets of the same size as the droplets ejected when the ink temperature is in the normal temperature range.

  According to the above-described configuration, the output voltage of the power supply circuit can be corrected by the temperature of the ink, so that the fluctuation of the discharge speed of the ink due to the temperature fluctuation of the ink can be suppressed.

  An example of the correction of the output voltage by the viscosity of the ink performed by the FPGA 51 in step S103 will be described with reference to FIG. Information indicating the correction coefficient corresponding to the viscosity of the ink as shown in FIG. 12 is stored in advance in the non-volatile memory 62. In the example shown in FIG. 12, the viscosity of the ink is divided into three categories of low, normal and high. Numerical values in FIG. 12 are correction coefficients for correcting the output voltage of each power supply. Correction coefficients corresponding to the three divisions of the viscosity of the ink are stored for each of the power supplies 1 to 5. These correction coefficients are used to calculate a new output voltage value by multiplying the value of the output voltage determined by the voltage setting at the time of printing operation stored in the non-volatile memory 52 after correction based on the above ink temperature. Is a factor that Then, the FPGA 51 updates the voltage setting stored in the non-volatile memory 52 as a voltage setting at the time of printing operation in which new values as output voltages are associated with the respective power supplies. At this time, the FPGA 51 calculates the output voltage of each of the power supplies 1 to 5 using the correction coefficient corresponding to the viscosity information stored in advance in the non-volatile memory 712. The user selects the viscosity of the ink used in the printing apparatus 1 in advance from the three values of "low", "normal", and "high" through the operation unit provided in the external device 9 and the printing device 1 described above. It can be specified by. Viscosity information indicating the viscosity designated by the user is stored in advance in the non-volatile memory 712.

  For example, when the viscosity information stored in the non-volatile memory 712 is information indicating “low”, the correction coefficient set as the correction coefficient when the viscosity of the ink is low is used to Correct the output voltage. The correction factor when the viscosity of the ink is low is set to a value smaller than 1.0 for each power supply. Therefore, when the ink is easily ejected due to the low viscosity of the ink, the output voltage can be lowered. In addition, since the correction coefficient when the viscosity of the ink is normal is set to a value of 1.0 for each power supply, the output voltage is not changed. Therefore, even in the case where the ink is easily ejected due to the low viscosity of the ink, it is possible to eject the droplet having the same size as the droplet ejected when the ink viscosity is normal. On the contrary, the correction coefficient when the viscosity of the ink is high is set to a value larger than 1.0. For this reason, when it is difficult to eject the ink because the ink viscosity is high, the output voltage can be increased. Therefore, even in the case where it is difficult to eject the ink because the ink viscosity is high, it is possible to eject a droplet having the same size as the droplet ejected when the ink viscosity is normal.

  According to the above-described configuration, the output voltage of the power supply circuit can be corrected by the viscosity of the ink, so that the fluctuation of the discharge speed of the ink due to the difference in the viscosity of the ink can be suppressed.

  After storing the information of the power supply setting at the time of printing operation in the non-volatile memory 52 at step S103, the FPGA 51 performs the droplet by each driving element 111 in the printing operation to be performed based on the raster data acquired at step S11 of FIG. The number of times of discharge is calculated (S104).

  Here, with reference to FIG. 13, an example of the method of calculating the number of times of ejection performed in step S104 will be described. FIG. 13 illustrates raster data of the first line of the 1680 drive elements 111 (drive element numbers 1 to 1680) and raster data of the second line. Note that raster data for the third and subsequent lines are omitted for convenience. The raster data stored in the DRAM 53 is a set of dot size data specifying the size of droplets ejected by each drive element 111, that is, the size of dots formed on the recording paper 100. The raster data stored in the DRAM 53 includes dot size data corresponding to 1680 drive elements 111 provided in the head unit 11. Further, raster data stored in the DRAM 53 includes dot size data of the number of lines required for image formation. That is, raster data stored in the DRAM 53 is data in which 1680 dot size data corresponding to 1680 driving elements are repeatedly provided by the same number as the number of lines necessary for image formation.

  Each dot size data is classified into four of "0" to "3". The dot size data “0” indicates that dots are not formed on the recording paper 100. A droplet is not discharged from the drive element 111 corresponding to the dot size data “0”. The dot size data “1” indicates that small dots are formed on the recording paper 100. The droplets ejected from the drive element 111 corresponding to the dot size data “1” become small beads with a small amount of liquid. The dot size data “2” indicates that a medium dot is formed on the recording paper 100. The droplets discharged from the drive element 111 corresponding to the dot size data “2” become a middle ball having a larger amount of liquid than a small ball. The dot size data “3” indicates that a large dot is formed on the recording paper 100. The droplets discharged from the drive element 111 corresponding to the dot size data “3” become large balls having a larger amount of liquid than the middle balls. The FPGA 51 can output a drive signal having a waveform corresponding to each dot size data described above to each drive element 111 by controlling the waveform generation circuit 30 via the control line 33 described above. Each time the recording paper 100 is conveyed by a predetermined distance, the head unit 11 repeats a one-line dot row consisting of 1680 dots aligned in the left-right direction by discharging droplets from 1680 nozzles. It can be formed on the recording paper 100. The head unit 11 performs printing of the image instructed to be printed by forming on the recording paper 100 a dot row of the necessary number of lines as the recording paper 100 is transported.

  In step S104, the FPGA 51 provides three counters, waveform 1 counter, waveform 2 counter, and waveform 3 counter, for each drive element 111, and counts the number of dot size data corresponding to each counter. The waveform 1 counter, the waveform 2 counter, and the waveform 3 counter are counters corresponding to dot size data “1”, dot size data “2”, and dot size data “3”, respectively. For example, the waveform 1 counter of drive element number 1 is a counter that counts dot size data “0” corresponding to the drive element 111 of drive element number 1. The waveform 2 counter of drive element number 1 is a counter that counts dot size data “2” corresponding to the drive element 111 of drive element number 1. The waveform 2 counter of drive element number 1 is a counter that counts dot size data “3” corresponding to the drive element 111 of drive element number 1. Thus, the FPGA 51 provides 1680 × 3 counters in the non-volatile memory 52, and counts the number of dot size data included in raster data for each drive element 111.

  As shown in FIG. 13, the FPGA 51 sequentially reads raster data stored in the DRAM 53 from dot size data of the first line, and increments the value of a counter corresponding to the read dot size data. In the example shown in FIG. 13, for the drive element corresponding to drive element No. 1, since the dot size data of the first line is “2” and the dot size data of the second line is “2”, waveform 2 The counter is incremented from 0 to 1, 1 to 2. On the other hand, the waveform 1 counter and the waveform 3 counter remain at zero. The driving elements 111 corresponding to the other driving element numbers 2 to 1680 are similarly counted.

  The total value of the count values of the waveform 1 counter, the waveform 2 counter, and the waveform 3 counter indicates the number of times the droplet of the driving element 111 is discharged. For example, the number of discharges of droplets of the driving element 111 in which the value of the waveform 1 counter is 300, the value of the waveform 2 counter is 500, and the value of the waveform 3 counter is 200 is 1000 times. In the present embodiment, the total value of the three counters is calculated and treated as an index value indicating the degree of deterioration of the drive element. However, the present invention is not limited to this. For example, only the value of the waveform 3 counter corresponding to the large ball where the drive energy is largest may be used as the index value indicating the degree of deterioration of the drive element.

  Thus, after calculating the number of times of ejection of each drive element 111, the FPGA 51 determines whether the print mode is the high image quality mode (S105). The FPGA 51 can determine whether the print mode is the high image quality mode by determining whether the print mode identification information acquired in step S11 of FIG. 8 is information indicating the high image quality mode. .

  When the high image quality mode is set (YES in S105), the FPGA 51 performs the processing of step S109 described later and the processing of step 110 described later without performing the processing of steps S106 to S108 described later. In the present embodiment, in the case of the high image quality mode, the power allocation in the printing operation may be changed from the power allocation in the initial state in order to give priority to the image quality over extending the life of the drive element 111. do not do. Therefore, in the case of the high image quality mode, the power supply circuit to be connected to each drive element 111 is selected in accordance with the power supply allocation information in the initial state stored in the non-volatile memory 62 in step 111 described later.

  If the high image quality mode is not set (NO in S105), that is, if the normal mode is set, the FPGA 51 changes the number of ejections calculated for each driving element 111 in S104 described above and the change of the power supply allocation stored in the non-volatile memory 62. According to the rule, the assignment of the power source connected to each drive element 111 is changed (S106), and the changed power source assignment information is stored in the non-volatile memory 52 as the power source assignment information at the time of printing operation.

  Next, the FPGA 51 determines whether there is a power supply circuit in which the number of connected drive elements is not appropriate (S107). In each of the power supply circuits 21 to 25, the upper limit number of the number of connections that can stably supply power when the plurality of drive elements are simultaneously connected is predetermined. If there is a power supply circuit in which the number of drive elements to be connected exceeds the predetermined upper limit number, the FPGA 51 determines that there is a power supply circuit in which the number of drive elements is not appropriate (YES in S107) Among the drive elements 111 belonging to the group, drive elements with a small number of ejections in the printing operation to be performed from now are allocated to another power source (S108).

  Specifically, when the number of connected drive elements is two more than the upper limit number, among the drive elements assigned to the power supply circuit, the drive element with the smallest number of discharges and the second number of discharges. Are assigned to the other drive elements. As described above, since the number of ejections is assigned to the other power supply circuit from the smallest, the adverse effect on the image quality can be reduced. For example, in the present embodiment, among the drive elements 111 to which the power supply 1 is allocated in the initial state, the drive elements 111 having the number of ejections of 10,000 or more and less than 15,000 times are power supplies in step S106 described above. 2 is changed to be assigned.

  However, in the initial state, when the number of drive elements 111 to which the power supply 2 is originally assigned is large, there is a risk that the number of drive elements 111 connected to the power source 2 may exceed the allowable number in the power assignment after change. is there. Therefore, among the drive elements 111 constituting the drive element group 2 (the drive element group to which the power supply 2 is assigned in the initial state), the FPGA 51 has the number of the drive elements 111 whose number of ejections is smaller than 15,000. Among the drive elements constituting the drive element group 1 (the drive element group to which the power supply 1 is assigned in the initial state), the sum of the number of ejections is 10,000 or more and less than 15,000 times. However, when it becomes equal to or higher than a predetermined threshold value, among the drive elements constituting the drive element group 2, a part of the drive elements 111 whose number of ejections is smaller than 15,000 times is different from the power supply 1 The power supply allocation information is updated so as to be connected to any one of the power supplies 3, 4 and 5. As the power source to be changed from the power source 2, any of the power source 1, the power source 3, the power source 4 and the power source 5 may be selected, but for example, the power source 3 may be selected as the power source to be changed from the power source 2.

  Thus, in step S108, the FPGA 51 updates the information of power supply allocation at the time of printing operation stored in the non-volatile memory 52, and returns to the process of step S107. Then, in addition to the power supply circuit in which the number of drive elements connected in the process of step 108 described above is reduced, it is determined whether there is a power supply circuit in which the number of connection of drive elements is not appropriate. Thus, the FPGA 51 repeats the processes of steps S107 and S108 until the number of connections of all the power supply circuits 21 to 25 becomes appropriate.

  If there is no power supply circuit having an inappropriate number of drive elements (NO in S107), that is, if the number of drive elements of all the power supply circuits is appropriate, the FPGA 51 stores the power supply during printing operation stored in the non-volatile memory 52. The output voltage is set according to the setting information (S109). Specifically, the FPGA 51 outputs a digital signal specifying the output voltage of each power supply circuit to the D / A converter 20.

  Then, the FPGA 51 controls each of the n selectors 90 (1) to 90 (n) according to the information of the power supply allocation at the time of printing operation stored in the non-volatile memory 52 to control each signal line 34. The power supply circuit for generating the drive signal to be output to is selected (S110), and the process is ended.

  In the embodiment described above, as shown in FIG. 7, among the drive elements 111 to which the power supply 1 is assigned in the initial state, the number of ejections is 10,000 or more and less than 15,000. The power supply assignment is changed such that the power supply 2 is assigned and the power supply 3 is assigned to the driving element 111 whose ejection frequency is 15,000 or more, but the present invention is not limited to this. For example, among the drive elements 111 to which the power supply 1 is assigned in the initial state, the power supply 2 may be assigned to all the drive elements 111 having the number of ejections of 10,000 or more. Also, for example, among the drive elements 111 to which the power supply 1 is assigned in the initial state, the power supply 5 is allocated to all the drive elements 111 having the number of ejections of 10,000 or more. If it is a power supply, any of the power supplies 2 to 5 may be allocated.

  According to the present embodiment, among the drive elements 111 to which the power supply 1 is assigned in the initial state, the power supply 2 is assigned to the drive elements 111 having the number of ejections of 10,000 or more and less than 15,000 times. The allocation of the power supply is changed such that the power supply 3 is allocated to the driving element 111 having the number of ejections of 15,000 times or more. For this reason, according to the present embodiment, the power supply according to the number of times the droplet is discharged by the drive element 111, as compared to the case where the drive element whose number of times of discharge is 10,000 or more is uniformly set to the other power supply 2 or the like. The assignment of the above can be set more finely, and the load on each drive element 111 can be made more even.

  Further, according to the present embodiment, in the drive element 111 to which the power supply 2 is allocated in the initial setting, the power supply is allocated such that the power supply 3 is allocated to the drive element 111 having the number of ejections of 15,000 or more. It has changed. However, in the drive element 111 to which the power supply 2 is assigned in the initial setting, the assignment of the power supply is not changed according to the number of times of ejection, and all the drive elements 111 are uniformly assigned to the power supply 2 with the initial setting. It is also good. According to the above-described embodiment, since the allocation change of the power supply is performed in the two groups to which the power supply 1 and the power supply 2 are allocated in the initial setting, the target drive element group is increased, and the life is considered as a result. Since the number of driving elements 111 is increased, the life of the head unit 11 can be further prolonged.

  In the example of FIG. 7, when the number of times of ejection is 15,000 or more, the power supply 3 is allocated to each drive element 111 constituting the group of the power supply 1 and the power supply 2. In this case, the number of driving elements 111 for which the number of times of ejection is 15,000 or more is too large, and may exceed the allowable number of driving elements 111 that can be connected to the power supply 3 at one time.

  Therefore, as shown in FIG. 10, the power supply assignment is changed also for the drive element 111 to which the power supply 3 is assigned in the initial state, and for the drive element 111 whose ejection frequency exceeds 15,000 times. It is also good. In the example shown in FIG. 10, the power supply 4 is changed to be allocated to the driving element 111 whose number of ejections exceeds 15,000 times.

  With the above-described configuration, in step 106 of FIG. 9, it is possible to prevent the occurrence of more than the allowable number of driving elements for a specific power supply (for example, power supply 3). This can prevent the processing from step 107 to step S108 in FIG. 9 from being repeated many times. Alternatively, even if the processes of steps S107 to S108 in FIG. 9 are omitted, the number of connection of driving elements to each power supply in the initial state is set in advance to a fixed number smaller than the allowable number. It is possible to prevent the load from increasing more than the allowable number.

  FIG. 14 is an explanatory view showing an example of the history information updated in step S16 of FIG. As shown in FIG. 14, in the non-volatile memory 62, values indicating the total number of ejections and the total drive energy up to the present are stored as history information in association with the respective drive elements. There are two types of values for both the total number of ejections and the total drive energy. One is when the waveform factor is not considered (no waveform factor) and the other is when the waveform factor is considered (with waveform factor). The waveform coefficient is a coefficient determined according to the above-described waveform number, and represents the magnitude of the discharge volume. As described above, these values are updated each time one print job ends.

  If the number of ejections of the drive element number i in one print job is represented by ni, the total number of ejections without waveform coefficients, that is, the total number of ejections by all print jobs executed in the past is sum (ni) Can be represented by Here, ni is not counted separately for each size of a droplet to be ejected, and is a numerical value incremented by one each time one of a large ball, a middle ball and a small ball is discharged. In addition, nai represents the number of ejections of small beads of driving element number i in one print job, and nbi of the number of ejections of center balls of driving element number i in one print job, and represents one print job If the number of discharges of the large ball with the drive element number i is represented by nci, the number of discharges in one print job with the waveform coefficient is (nai × wa) + (nbi × wb) + (nci × wc) Can be represented by wa is a waveform coefficient of a small ball, wb is a waveform coefficient of a middle ball, and wc is a waveform coefficient of a small ball. Therefore, the total number of times of ejection when there is a waveform coefficient can be represented by sum (nai × wa) + sum (nbi × wb) + sum (nci × wc).

  Further, when the output voltage connected to the drive element of drive element number i in one print job is represented by vi, the total drive energy in the case of no waveform coefficient can be represented by sum (ni × vi) . The total drive energy with the waveform coefficient can be represented by sum (nai × vi × wa) + sum (nbi × vi × wb) + sum (nci × vi × wc).

  As described above, the FPGA 51 counts the total number of discharges “sum (ni)” with no waveform coefficient and the total number of discharges with waveform coefficient “sum (nai × wa) in step S17 described above each time a print job is completed. + Sum (nbi × wb) + sum (nci × wc) ′ ′, total drive energy “sum (ni × vi) ′ ′ without waveform coefficient, total drive energy“ sm (nai × vi × wa) + sum (nbi ×) with waveform coefficient Four values of vi × wb) + sum (nci × vi × wc) ′ ′ are updated for each driving element.

  That is, every time the print job is completed, the number of times of driving "ni" without the waveform coefficient relating to the print job is added to "sum (ni) stored in the non-volatile memory 62. Further, the print job is completed. Every time the printing job is executed, the number of times of driving “(nai × wa) + (nbi × wb) + (nci × wc)” with the waveform coefficient is stored in the non-volatile memory 62 “sum (nai × wa) + sum (nbi × wb) + sum (nci × wc) ”In addition, every time the print job ends, the drive energy“ ni × vi ”having no waveform coefficient related to the print job is stored in the non-volatile memory 62 is added to “sum (ni × vi)” stored in 62. Also, each time a print job is completed, driving energy “(nai “Sum (nai × vi × wa) + sum (nbi × vi × wb)” stored in the non-volatile memory 62 “× vi × wa) + (nbi × vi × wb) + (nci × vi × wc)” + Sum (nci × vi × wc) ”.

  As described above, since the history information is updated in step S16 of FIG. 8, the total number of times of ejection of the droplets ejected by each driving element 111 can be acquired in step S13 of FIG. In the above-described embodiment, in step S102 of FIG. 9, the sum (ni), which is the total number of ejections without a waveform coefficient, indicates the drive voltage of all the power supplies when the drive elements 111 have a predetermined number or more. It shall be changed to raise. However, the present invention is not limited to this, and the total number of ejections “sum (nai × wa) + sum (nbi × wb) + sum (nci × wc)” with waveform coefficient, total driving energy “sum (without waveform coefficient)” Any value of ni × vi) or total drive energy “sum (nai × vi × wa) + sum (nbi × vi × wb) + sum (nci × vi × wc)” with a waveform coefficient is a predetermined value The setting of the output voltage of each power supply may be changed when there is a driving element 111 that exceeds.

  Further, in the above-described embodiment, the number of ejections in the printing operation to be performed from now on is used as index value information indicating the degree of deterioration of the drive element 111 in S106 of FIG. The allocation of the power supply is changed so that the drive element 111 is allocated to a power supply having a lower output voltage than the power supply allocated in the initial state. However, the present invention is not limited to this. For example, the total number of discharges “sum (ni)” without waveform coefficients stored in the non-volatile memory 62 as history information, the total number of discharges with waveform coefficients “sum (nai × wa) + sum (nbi × wb) + sum (Nci × wc) ′ ′, total drive energy “sum (ni × vi) ′ ′ without waveform coefficient, total drive energy ′ ′ with waveform coefficient“ sum (nai × vi × wa) + sum (nbi × vi × wb) + sum (nci) ” The power supply allocated in the initial state when any of the four values of x vi x w c) ”is used as index value information indicating the degree of deterioration of each drive element and the value exceeds a predetermined threshold value. The assignment of power supplies may be changed to be assigned to a lower voltage power supply.

  According to the above-described configuration, when the power is allocated, the power can be allocated in consideration of not only the index value information of the driving element according to the received print job but also the index value information of the driving element in the past. The service life of the head unit 11 can be extended in consideration of the past frequency of use of the drive element and the degree of deterioration.

Second Embodiment
In the first embodiment described above, a power supply circuit connected to each waveform generation circuit 30 taking a droplet discharge device as an example provided with waveform generation circuits 30 for generating drive signals for each of N drive elements 111 as an example Although the assignment change of has been described, it is not limited to this. For example, the droplet discharge device includes a drive signal generation circuit that generates a common drive signal to the N drive elements 111 instead of individually generating a drive signal for each of the N drive elements 111. It is also good. In this case, a switching circuit that switches whether or not to output the drive signal generated by the drive signal generation circuit to each drive element 111 is disposed between the drive element 111 and the drive signal generation circuit. Then, a controller composed of a processor such as a CPU and a hardware element such as a drawing memory controls the switching circuit in accordance with the image data to be printed, thereby causing each driving element 111 to discharge droplets. In such a droplet discharge device having a drive signal generation circuit common to a plurality of drive elements 111, a plurality of drive signal generation circuits having different electric energy of the drive signal to be generated are prepared in advance, Japanese Patent Application Laid-Open No. 2008-197511 discloses a droplet discharge device which selects a drive signal generation circuit to be connected according to the discharge characteristics of the liquid droplets 111. As described above, in the droplet discharge device which selects the drive signal generation circuit to be connected according to the discharge characteristic of the drive element 111, the drive signal generation circuit to be connected to each drive element 111 may be changed from the initial state. .

  FIG. 15 is a schematic block diagram of the second embodiment. The droplet discharge apparatus 211 according to the second embodiment includes N drive elements 111, a switching circuit 280, a drive signal selection circuit 290, a drive signal generation circuit 221, a drive signal generation circuit 222, and a drive signal generation circuit. 223, a drive signal generation circuit 224, a controller 251, and a non-volatile memory 252. The four drive signal generation circuits 221 to 224 in the second embodiment are the first D / A converter 36, the second D / A converter 37, and the third D / A disclosed in JP-A-2008-197511. The components correspond to the converter 38 and the fourth D / A converter 39. Further, the drive signal selection circuit 290 in the second embodiment is a component equivalent to the COM selection circuit 40 disclosed in Japanese Patent Laid-Open No. 2008-197511. The switching circuit 280 in the second embodiment is a component equivalent to the switching circuit 50 disclosed in Japanese Patent Application Laid-Open No. 2008-197511. Further, the controller 251 in the second embodiment is hardware configured from a plurality of hardware elements such as the drawing data memory 32 and the control device 11 disclosed in JP-A-2008-197511.

  In the second embodiment, it is assumed that the drive signals generated by the drive signal generation circuits 221 to 224 respectively generate drive signals having the same waveform for the rise time and the fall time of the waveform. However, the voltage values (peak heights) of the drive signals generated by the drive signal generation circuits 221 to 224 are different. The voltage value of the drive signal 1 generated by the drive signal generation circuit 221 is higher than the voltage value of the drive signal 2 generated by the drive signal generation circuit 222, and the voltage value of the drive signal 2 generated by the drive signal generation circuit 222 is The voltage value of the drive signal 3 generated by the drive signal generation circuit 3 is higher than the voltage value of the drive signal 3 generated by the drive signal generation circuit 223 than the voltage value of the drive signal 4 generated by the drive signal generation circuit 224. high. That is, the electrical energy of drive signal 1 is higher than the electrical energy of drive signal 2, the electrical energy of drive signal 2 is higher than the electrical energy of drive signal 3, and the electrical energy of drive signal 3 is greater than the electrical energy of drive signal 4. Also high. When discharging droplets the same number of times, the drive element 111 driven by the drive signal 1 with the highest electrical energy is more than the drive element 111 driven by the drive element 2 with lower electrical energy than the electrical energy of the drive signal 1 The deterioration of the drive element 111 is premature.

  Therefore, in the second embodiment, the assignment of the drive signal generation circuits 221 to 224 connected to each drive element 111 is changed from the assignment of the initial state according to the number of times of droplet ejection. The operation of the droplet discharge device 211 in the second embodiment will be described below with reference to FIGS.

  FIG. 16 is an explanatory view showing assignment of the drive signal generation circuit in the initial state. In the non-volatile memory 252, allocation information of the drive signal generation circuit in an initial state set in advance according to the ejection characteristics of each drive element 111 is stored. In the description of the second embodiment, a group including the drive elements 111 to which the drive signal generation circuit 221 is assigned in the initial state is referred to as a drive element group 1. A group formed of the drive elements 111 to which the drive signal generation circuit 222 is assigned in the initial state is referred to as a drive element group 2. A group formed of drive elements 111 to which the drive signal generation circuit 223 is assigned in the initial state is referred to as a drive element group 3. A group including drive elements to which the drive signal generation circuit 224 is assigned in the initial state is referred to as a drive element group 4.

  FIG. 17 is an explanatory view showing the rule of changing the assignment of the drive signal generation circuit in the second embodiment. In the second embodiment, the number of discharges of droplets by each drive element 111 in the printing operation to be performed from now is obtained, and the printing operation is performed in a state where the assignment of the drive signal generation circuit is reviewed. FIG. 17 shows how the drive signal generation circuits 221 to 224 assigned to each drive element 111 of each drive element group are changed according to the number of ejections. For example, the drive element group 1 to which the drive signal generation circuit 221 is assigned in the initial state is changed as follows. The drive signal generation circuit 221 is assigned to the drive element 111 whose ejection frequency is smaller than the first threshold (for example, 10,000 times) without changing from the initial state. On the other hand, the drive signal generation circuit 222 is allocated to the drive element 111 whose ejection frequency is equal to or more than the first threshold and smaller than the second threshold (for example, 15,000 times). Further, the drive signal generation circuit 223 is assigned to the drive element 111 whose ejection frequency is equal to or higher than a second threshold (for example, 15,000 times). The drive element group 2 to which the drive signal generation circuit 222 is assigned in the initial state is changed as follows. The drive signal generation circuit 222 is assigned to the drive element whose ejection frequency is smaller than the second threshold (for example, 15,000 times), as in the initial state. On the other hand, the drive signal generation circuit 223 is assigned to the drive element 111 whose ejection frequency is smaller than the second threshold (for example, 15,000 times). Further, for the drive element groups 3 and 4 to which the drive signal generation circuits 223 and 224 are assigned in the initial state, the assignment of the drive signal generation circuit is not changed regardless of the number of ejections. That is, even after reviewing the assignment of the drive signal generation circuit, the same drive signal generation circuit as in the initial state is assigned. Rules for changing the assignment as shown in FIG. 17 are stored in advance in the non-volatile memory 262. The number of times the droplet is discharged by the driving element 111 can be calculated, for example, from raster data as in the first embodiment.

  FIG. 18 is a flow chart showing an example of the processing procedure by the droplet discharge device 211 of the second embodiment. The process illustrated in FIG. 18 is started by, for example, the controller 251 when the droplet discharge device 211 is powered on. First, the controller 251 determines whether to start printing (S210). Whether to start printing is based on whether the user has issued a printing instruction by the user via an external device connected to the droplet discharge device 211 or an operation unit (not shown) of the droplet discharge device 211. To judge.

  When printing is started (YES in S210), the controller 251 selects raster data, which is a set of data for specifying the size of droplets to be ejected from each nozzle, based on the image data of the image instructed to be printed by the user. It is created and stored in the non-volatile memory 252 (S211).

  The controller 251 reads out the allocation information of the drive signal generation circuit in the initial state shown in FIG. 16 from the non-volatile memory 262 (S212), and performs processing of setting the drive signal generation circuit (S213). The process of setting the drive signal generation circuit will be described later. When the controller 251 determines that printing will not be started (NO in S210), the controller 251 performs processing in step S215 described later.

  The controller 251 performs the printing operation in a state where the setting of the drive signal generation circuit is performed in step S213 (S214). Then, the controller 251 determines whether the power OFF operation has been performed (S215). If the power-off operation has not been performed (NO in S15), the process returns to S210, and it is determined whether printing is to be started. If the power-off operation has been performed (YES in S215), the controller 251 ends the process.

  FIG. 19 is a flow chart showing an example of a processing procedure of setting of a drive signal generation circuit by the droplet discharge device 211 of the second embodiment. The controller 251 calculates the number of times of ejection of droplets by each driving element 111 in the printing operation to be performed from now on the basis of the raster data created in step S211 of FIG. 18 (S301). The calculation of the number of times of ejection of each drive element 111 is the same as the process performed in step 104 in FIG. 9 of the first embodiment, so the description will be omitted.

  The controller 251 is connected to each drive element 111 in accordance with the ejection frequency calculated for each drive element 111 in step S301 and the rule of changing the assignment of the drive signal generation circuit stored in the nonvolatile memory 262. The assignment of the generation circuit is changed (S302), and the assignment information of the drive signal generation circuit after the change is stored in the non-volatile memory 252 as the assignment information of the drive signal generation circuit at the time of printing operation.

  The controller 251 generates the drive signal to be output to each drive element 111 by controlling the drive signal selection circuit 290 according to the information of the assignment of the drive signal generation circuit at the time of printing operation stored in the non-volatile memory 252 The drive signal generation circuit is selected (S303), and the process ends.

  As described above, the droplet discharge device 211 of the second embodiment generates a drive signal having a waveform different from that of the N nozzles and the N drive elements provided corresponding to the N nozzles. A signal generation circuit is disposed between each drive element of N drive elements and M drive signal generation circuits, and M drive signal generation circuits are arranged for each drive element of N drive elements. A selection circuit for selectively connecting one of the drive signal generation circuits and each drive element group of M drive element groups divided according to the type of drive signal supplied to the N drive elements The controller includes a memory storing assignment information indicating a drive signal generation circuit assigned to the drive element.

  The controller indicates a value of the degree of deterioration of the drive element for each of the drive elements forming drive element group A which is one of the M drive element groups after detecting a predetermined trigger such as a printing instruction. After acquiring index value information and acquiring index value information, in the allocation information, electric energy smaller than the electric energy of the drive signal generated by the drive signal generation circuit A allocated to the drive element of the drive element group A is used. The selection circuit is controlled so as to connect each of the drive elements forming the drive element group B to which the drive signal generation circuit B that generates the drive signal is assigned, to the drive signal generation circuit B.

  The controller is a drive signal generation circuit which is different from the drive signal generation circuit B in each of the drive elements of which the value indicated by the index value information is greater than or equal to the first threshold among the plurality of drive elements constituting the drive element group A. The selection circuit is controlled to be connected to a drive signal generation circuit or drive signal generation circuit B which generates a drive signal of electrical energy smaller than the electrical energy of the drive signal generated by the drive signal generation circuit A.

  In addition, the controller selects one of the plurality of drive elements forming drive element group A so that each of the drive elements whose value indicated by the index value information is smaller than the first threshold is connected to drive signal generation circuit A. Control the circuit. By setting the assignment of the drive signal generation circuit by controlling the selection circuit as described above, the printing operation is started.

<Other Modifications>
In the above embodiment, the drive element groups are divided according to whether the discharge speed of the droplets by each drive element is fast or slow, but the division of the drive element groups is limited to the discharge speed. For example, the discharge amount may be used.

  In the above-described embodiment, although the number of times of ejection is used as the index value information indicating the degree of deterioration of the drive element, the index value information is not limited to the number of times of ejection or the like. For example, a resonance frequency measuring unit as disclosed in FIG. 3 of JP-A-2004-9501 is provided, the resonance frequency at the time of driving the piezoelectric body is measured, and the reference resonance frequency is stored in a memory or the like. The degree of deterioration of the drive element may be detected by measuring the change in resonant frequency when the piezoelectric body is driven.

  In addition, there is an inkjet recording head of a type in which a heater for contacting the ink via a protective film is provided in the flow path for leading the ink to the discharge port. In such a type of recording head, for example, JP-A-2013-49224 The controller disclosed in FIG. 2 of the publication is provided, the minimum value of the drive parameter of the drive element from the time of mounting of the recording head is measured, and the measured value of the minimum value of the drive parameter is used as index value information. It can also be done. As the deterioration of the drive element progresses, the thickness of the protective film becomes thinner, heat is easily transmitted from the heater to the ink, the minimum pulse width necessary for ejection decreases, and the minimum value of the drive parameter decreases. The degree of degradation of the element can be estimated.

  In the present embodiment, the drive element 111 is described as a piezoelectric element having a first active portion and a second active portion for one pressure chamber, but the present invention is limited to this. It is not a thing. For example, a droplet discharge apparatus provided with a piezoelectric element having only one active portion for one pressure chamber, or a thermal jet system provided with a heater as a drive element and discharging a liquid with bubbles generated by the heater The present invention is applicable to any type of droplet discharge device such as a droplet discharge device.

  Although the control lines 33 (1) to 33 (n) are provided between the FPGA 51 and the driver IC 27 in the above-described embodiment, the present invention is not limited to this. For example, a serial signal line is provided between the FPGA 51 and the driver IC 27. In the FPGA 51, a signal to be sent out through the control lines 33 (1) to 33 (n) is converted to a serial signal, and the converted serial signal is It may be output to the driver IC 27 via a serial signal line. In this case, the driver IC 27 may convert serial signals into parallel signals, take out the signals transmitted by the control lines 33 (1) to 33 (n), and input the signals to n selectors and waveform generation circuits. Thereby, the number of wires between the FPGA 51 and the driver IC 27 can be reduced, or the number of pins required for the IC can be reduced.

  In the present embodiment, the flexible circuit board 60 and the second board 50 can be detachably connected by a connector. Thus, the head unit 11 including the flexible circuit board 60, the drive element 111, the nozzles, and the like can be separated from the second board 50, and only the head unit 11 can be replaced without removing the second board 50. Become. Further, the predetermined trigger is not limited to the print instruction, and for example, when the predetermined time has elapsed (for example, each time the predetermined time has elapsed), when the power on / off has been performed a predetermined number of times, etc. Can be included.

DESCRIPTION OF SYMBOLS 1 printing apparatus 2 case 3 platen 4 inkjet head 5, 6 conveyance roller 7 control apparatus 8 head holding part 9 external device 11 head unit 11a discharge port 111 drive element 111b, 111b 'capacitor 20 D / A converter 21, 22, 23 , 24, 25, 26 Power supply circuit 27 Driver IC
30 waveform generation circuit 50 second substrate 51 FPGA
62 Nonvolatile Memory 71 First Substrate 712 Nonvolatile Memory 211 Droplet Discharge Device 221, 222, 223, 224 Drive Signal Generating Circuit 251 Controller 252 Nonvolatile Memory

Claims (15)

N nozzles,
N driving elements provided corresponding to the N nozzles,
M power circuits for generating a drive signal to be supplied to each of the drive elements;
One power supply among the M power circuits is disposed between each of the N drive elements and the M power circuits, and for each of the N drive elements, A selection circuit for selectively connecting the circuits;
A memory storing assignment information indicating a power supply circuit to be assigned to each drive element of each drive element group of M drive element groups divided according to the voltage of the drive signal supplied to the N drive elements;
With controller and
The controller
After detecting a predetermined trigger, index value information indicating a value of the degree of deterioration of the drive element is acquired for each of the drive elements constituting the drive element group A which is one of the M drive element groups,
A drive to which a power supply circuit B that outputs a voltage lower than a voltage output from a power supply circuit A assigned to the drive element of the drive element group A in the assignment information is assigned after obtaining the index value information Each of the drive elements constituting the element group B is connected to the power supply circuit B,
Each of the plurality of drive elements constituting the drive element group A, which has a value indicated by the index value information equal to or greater than a first threshold, is a power supply circuit different from the power supply circuit B, and the power supply circuit It is connected to a power supply circuit that outputs a voltage lower than the voltage output from A or the power supply circuit B,
The selection circuit is controlled to connect each of the drive elements whose value indicated by the index value information is smaller than the first threshold among the plurality of drive elements constituting the drive element group A to the power supply circuit A. What is claimed is: 1. A droplet discharge device characterized by: The controller
Among the plurality of drive elements constituting the drive element group A, each of the drive elements whose values indicated by the index value information are greater than or equal to the first threshold and smaller than the second threshold are the power circuits B. It is connected to a power supply circuit C which is a different power supply circuit and outputs a voltage lower than the voltage output from the power supply circuit A,
The power supply circuit different from the power supply circuit B and the power supply circuit C is a drive element having a value indicated by the index value information among the plurality of drive elements constituting the drive element group A that is equal to or greater than the second threshold. 3. The droplet discharge device according to claim 1, wherein the selection circuit is controlled to be connected to a power supply circuit that outputs a voltage lower than the voltage output from the power supply circuit A or to the power supply circuit B. . The controller
A drive to which a power supply circuit C that outputs a voltage lower than the voltage output from the power supply circuit A and higher than the voltage output from the power supply circuit B is assigned in the assignment information after detecting the predetermined trigger The index value information is acquired for each of the drive elements constituting the element group C,
Among the plurality of drive elements constituting the drive element group C after acquiring the index value information, each of the drive elements whose value indicated by the index value information is equal to or greater than a second threshold value is the power supply circuit B It is connected to a power supply circuit which is a different power supply circuit and outputs a voltage lower than the voltage output from the power supply circuit C, or the power supply circuit B.
Among the plurality of drive elements constituting the drive element group C, each of the drive elements whose value indicated by the index value information is smaller than the second threshold is connected to the power supply circuit C.
A power supply circuit which is different from the power supply circuit B or the power supply circuit C, of the plurality of drive elements constituting the drive element group A, wherein each of the drive elements whose value indicated by the index value information is equal to or more than the first threshold 2. The droplet discharge device according to claim 1, wherein the selection circuit is controlled to be connected to a power supply circuit that outputs a voltage lower than a voltage output from the power supply circuit A.   4. The droplet discharge device according to claim 3, wherein the value of the second threshold is larger than the value of the first threshold. The controller
After acquiring the index value information, among a plurality of drive elements constituting the drive element group C, a part of drive elements among drive elements whose value indicated by the index value information is smaller than the second threshold value 5. The droplet discharge device according to claim 4, wherein the selection circuit is controlled such that each of the selection circuits is connected to any one of the M power circuits different from the power circuit C. . The controller
Among the plurality of drive elements constituting the drive element group C, the number of drive elements whose value indicated by the index value information is smaller than the second threshold, and the plurality of drive elements constituting the drive element group A In the case where the sum of the value indicated by the index value information and the number of driving elements to be connected to the power supply circuit C among the driving elements having the first threshold value or more is equal to or more than the threshold value, The liquid according to claim 5, wherein the selection circuit is controlled to connect each of the drive elements to any one of the M power circuits different from the power circuit C. Drop discharge device. The controller
Obtain raster data related to the print job to be executed next,
The droplet discharge device according to any one of claims 1 to 6, wherein the number of discharges of the droplet for each drive element is acquired from the raster data as the index value information. The controller
A history of the number of droplet discharges is stored in the memory for each drive element,
The droplet discharge device according to any one of claims 1 to 7, wherein the number of times of discharge for each of the drive elements is acquired from the memory as the index value information. The controller
When a droplet is discharged by the drive element, a value corresponding to the output voltage of the power supply circuit connected to the drive element is integrated for each drive element by the number of times the droplet is discharged by the drive element. Calculate
The integrated value is stored in the memory for each drive element,
The droplet discharge device according to claim 1, wherein the integrated value is acquired from the memory for each drive element as the index value information. The controller
An integrated value is calculated by integrating, for each drive element, a value corresponding to the volume of the droplet discharged by the drive element, by the number of times the droplet is discharged by each drive element.
The integrated value is stored in the memory for each drive element,
The droplet discharge device according to any one of claims 1 to 9, wherein the integrated value is acquired from the memory for each of the drive elements as the index value information. The controller
The total value of the number of times the liquid is discharged by the N driving elements is counted for each of the N driving elements,
When there are driving elements whose total value exceeds a predetermined number, the M power circuits are controlled to increase the output voltage of each power circuit of the M power circuits by a predetermined voltage. The droplet discharge device according to any one of claims 1 to 10. Equipped with a temperature sensor,
The controller
The M power circuits are controlled to correct the output voltage of each of the M power circuits according to temperature information from the temperature sensor, according to any one of claims 1 to 11. Droplet discharge device. The controller
Obtain characteristic information on the characteristics of the liquid to be discharged,
The droplet discharge device according to any one of claims 1 to 12, wherein the M power circuits are controlled to correct the output voltage of each of the M power circuits according to the characteristic information. . The controller
Acquire mode information for identifying the print mode related to the print job,
When the acquired mode information is mode information indicating the first mode, each of the drive elements constituting the drive element group A is selected from the drive element group A in the allocation information regardless of the degree of deterioration of the drive element. The droplet discharge device according to any one of claims 1 to 13, wherein the selection circuit is controlled so as to be connected to a power supply circuit A associated therewith. N nozzles,
N driving elements provided corresponding to the N nozzles,
M drive signal generation circuits that generate drive signals having different waveforms respectively;
Among the M drive signal generation circuits, each drive element of the N drive elements is disposed between the drive elements of the N drive elements and the M drive signal generation circuits. A selection circuit for selectively connecting one of the drive signal generation circuits of
A memory storing assignment information indicating drive signal generation circuits to be assigned to drive elements of drive element groups of M drive element groups divided according to types of drive signals supplied to the N drive elements; ,
With controller and
The controller
After detecting a predetermined trigger, index value information indicating a value of the degree of deterioration of the drive element is acquired for each of the drive elements constituting the drive element group A which is one of the M drive element groups,
After acquiring the index value information, the assignment information generates a drive signal of electric energy smaller than the electric energy of the drive signal generated by the drive signal generation circuit A assigned to the drive element of the drive element group A. Each of the drive elements constituting the drive element group B to which the drive signal generation circuit B is assigned is connected to the drive signal generation circuit B,
The drive signal generation circuit is different from the drive signal generation circuit B in each of the drive elements of which the value indicated by the index value information is equal to or greater than a first threshold value among the plurality of drive elements constituting the drive element group A. Connection with the drive signal generation circuit or the drive signal generation circuit B which generates a drive signal of electric energy smaller than the electric energy of the drive signal generated by the drive signal generation circuit A.
The selection circuit is connected to the drive signal generation circuit A such that each of the drive elements having a value indicated by the index value information is smaller than the first threshold among the plurality of drive elements constituting the drive element group A. A droplet discharge device characterized by controlling

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