JP4747871B2 - Liquid discharge head control device and liquid discharge head control method - Google Patents

Description

  The present invention relates to a liquid ejection head control apparatus, a liquid ejection head control method, and a program.

A liquid discharge head and a control device for controlling the liquid discharge head are used in a liquid discharge apparatus such as an ink jet printer. Some of these control devices simultaneously generate a plurality of drive signals in a printing cycle, and selectively apply a drive pulse included in each drive signal to a piezo element included in a liquid discharge head (see, for example, Patent Document 1). .) The selective application of the drive pulse is performed by applying a waveform portion of the drive signal to the piezo element at a timing defined by, for example, a latch pulse or a change pulse (also called a channel pulse) (for example, Patent Document 2). See).
JP 2000-52570 A Japanese Patent Laid-Open No. 10-81013

  When the waveform portion included in the drive signal is selectively applied to the piezo element at the timing of the latch pulse or the change pulse, noise may occur in each drive signal. This is presumably because the amount of current for the piezo element changes abruptly. For example, when a certain waveform portion is applied to many piezo elements, the ground potential may change at the moment when the application is stopped all at once and appear as noise of each drive signal. The noise generated in the drive signal is not a problem if the magnitude is small, but if it is excessively large, there is a possibility that the ink ejection may be hindered.

  The present invention has been made in view of such circumstances, and an object thereof is to reduce the adverse effects of noise.

The main invention for achieving the object is as follows:
Controlling the liquid ejection head having at least performing device performs operation for ejecting liquids, a control system for a liquid discharge head,
(A) The liquid discharge head changes the volume of the pressure chamber communicating with the nozzle by the operation of the element,
(B) a first drive signal having a plurality of first waveform portions that return to the reference voltage after undergoing a voltage change of a pattern determined in accordance with an operation to be performed by the element starting from a reference voltage, and the reference voltage Drive signal generation that simultaneously generates a second drive signal having a second waveform portion that returns to the reference voltage after undergoing a voltage change of a pattern determined according to an operation to be performed by the element that is started from And
(C) A plurality of first timing pulses indicating the generation start timing of the first waveform portion are generated corresponding to each of the plurality of first waveform portions, and a second indicating the generation start timing of the second waveform portion. A timing pulse generating unit that generates a timing pulse corresponding to the second waveform unit;
At least one of the first timing pulses corresponding to another first waveform portion generated next to a certain first waveform portion is a part of a voltage change pattern included in any of the second waveform portions. And generating a change portion for returning the voltage to the reference voltage after the liquid is discharged ,
At least one of the second timing pulses corresponding to another second waveform part generated next to a second waveform part is a part of a voltage change pattern of any of the first waveform parts. A timing pulse generator that generates within a period in which another change part for returning the voltage to the reference voltage after the liquid is discharged , and
(D) Based on the timing defined by one of the first timing pulse and the second timing pulse, either the first waveform portion or the second waveform portion is applied to the element, A signal applying unit that operates the element in accordance with a voltage change pattern that either one has,
The second waveform part is generated following the discharge change part for changing the voltage to a contraction voltage corresponding to the pressure chamber in the contracted state in order to discharge the liquid, and the contraction It goes through the voltage change of the pattern including the part that maintains the voltage,
The change part for returning to the reference voltage is generated following the part for maintaining the contraction voltage, and the absolute value of the voltage change amount per unit time is calculated per unit time in the discharge change part. This is a liquid ejection head control device that is set smaller than the absolute value of the voltage change amount .

  Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

  At least the following will be made clear by the description of the present specification and the accompanying drawings.

  That is, (A) a liquid ejection head control device that controls a liquid ejection head having at least an element that performs an operation for ejecting liquid, and (B) an operation that is started from a reference voltage and that is performed by the element And a first drive signal having a plurality of first waveform portions that return to the reference voltage after undergoing a voltage change of a pattern determined according to the method, and an operation that is started from the reference voltage and that is to be performed by the element. A drive signal generation unit that simultaneously generates a second drive signal having a second waveform portion that returns to the reference voltage after undergoing a voltage change of the pattern, and (C) generation start timing of the first waveform portion A plurality of first timing pulses indicative of the second waveform portion corresponding to each of the plurality of first waveform portions and a second timing pulse indicating the generation start timing of the second waveform portion. A timing pulse generator for generating a second pulse corresponding to the second waveform portion, wherein the first timing pulse corresponding to another first waveform portion generated after a certain first waveform portion is (D) a timing pulse generator that generates a part of the voltage change pattern of the second waveform part and that is generated within a period in which a change part for returning the voltage to the reference voltage is generated after the liquid is discharged; One of the first waveform portion and the second waveform portion is applied to the element based on the timing defined by one of the first timing pulse and the second timing pulse, and either one of the first timing pulse and the second timing pulse is applied. A signal applying unit that operates the element in accordance with a voltage change pattern included in the liquid ejection head and a liquid ejection head control device including (E) can be realized.

  According to such a liquid ejection head control device, the first timing pulse corresponding to the other first waveform portion is a voltage change portion of the second waveform portion, and the voltage is applied after the liquid is ejected. The change portion for returning to the reference voltage is generated within a period in which the change portion is generated. Since this changed portion is generated after the liquid is discharged, even if noise occurs in the second waveform portion (second drive signal) during this period, it does not easily affect the liquid discharge. For this reason, the bad influence of the noise resulting from a 1st timing pulse can be reduced.

In this liquid discharge head control apparatus, the liquid discharge head changes the volume of the pressure chamber communicating with the nozzle by the operation of the element, and the second corrugated portion is arranged to discharge the liquid. A voltage change of a pattern including a change portion for discharge that changes the voltage to a contraction voltage corresponding to the pressure chamber in the contracted state, and a portion that is generated following the change portion for discharge and maintains the contraction voltage. The change part for returning to the reference voltage is preferably generated following the part for maintaining the contraction voltage.
According to such a control apparatus for a liquid discharge head, a portion for maintaining the contraction voltage is generated between the change portion for discharge and the change portion for returning to the reference voltage. For this reason, the change part for returning to a reference voltage can be produced | generated reliably after discharge of a liquid.

In this liquid discharge head control apparatus, the change portion for returning to the reference voltage is such that the absolute value of the voltage change amount per unit time is the absolute value of the voltage change amount per unit time in the change portion for discharge. It is preferable that the value is set smaller than the value.
According to such a control apparatus for a liquid ejection head, it is possible to prevent a problem that liquid is ejected even if the waveform of the changed portion for returning to the reference voltage is disturbed by noise.

In this liquid ejection head control device, the drive signal generation unit generates the second drive signal including a plurality of the second waveform units, and the timing pulse generation unit generates the plurality of second timing pulses. A plurality of the second waveform portions are generated corresponding to each of the second waveform portions, and the second timing pulse corresponding to another second waveform portion generated next to a certain second waveform portion is set to any one of the first waveforms. Preferably, it is generated within a period in which another change portion for returning the voltage to the reference voltage is generated after the liquid is discharged, which is a part of the voltage change pattern of the portion.
According to such a liquid ejection head control device, the second timing pulse corresponding to the other second waveform portion is a voltage change portion of the first waveform portion, and the voltage is applied after the liquid is ejected. It is generated within a period in which another change part for returning to the reference voltage is generated. Since the other changed portions are also generated after the liquid is discharged, even if noise occurs in the first waveform portion (first drive signal) during this period, it does not easily affect the liquid discharge. For this reason, the bad influence of the noise resulting from a 2nd timing pulse can be reduced.

In this liquid discharge head control device, the liquid discharge head changes the volume of the pressure chamber communicating with the nozzle by the operation of the element, and the first corrugated portion is arranged to discharge the liquid. Another discharge change part for changing the voltage to a contraction voltage corresponding to the pressure chamber in the contracted state, and another part that is generated following the other discharge change part and maintains the contraction voltage. It is preferable that the voltage change of the pattern is performed and the other change part for returning to the reference voltage is generated following the other part for maintaining the contraction voltage.
According to such a control apparatus for the liquid discharge head, another portion that maintains the contraction voltage is generated between another change portion for discharge and another change portion for returning to the reference voltage. For this reason, the other change part for returning to a reference voltage can be produced | generated reliably after discharge of a liquid.

In this liquid discharge head control apparatus, the other change part for returning to the reference voltage is that the absolute value of the voltage change amount per unit time is the voltage per unit time in the other change part for discharge. It is preferable that the amount of change is set smaller than the absolute value.
According to such a control apparatus for a liquid ejection head, it is possible to prevent a problem that the liquid is ejected even if the waveform of another changing portion for returning to the reference voltage is disturbed by noise.

In this liquid ejection head control device, the timing pulse generator changes the first timing pulse corresponding to the Nth (N is an integer greater than or equal to 2) first waveform portion to the reference voltage. Is generated within a period in which the second timing pulse corresponding to the Nth second waveform portion is generated at a certain portion of the reference voltage on the second drive signal side. It is preferable to produce | generate to.
According to such a liquid ejection head control device, the generation timing of noise caused by the first timing pulse and the generation timing of noise caused by the second timing pulse are deviated, so that these noises are superimposed. Can be prevented. For this reason, the bad influence resulting from noise can be prevented.

In this liquid ejection head control device, the timing pulse generator may return another second timing pulse corresponding to an Nth (N is an integer of 2 or more) second waveform portion to the reference voltage. When the change portion is generated within the generation period, the first timing pulse corresponding to the Nth first waveform portion is generated with a constant portion at the reference voltage on the first drive signal side. It is preferable to generate in a period.
According to such a liquid ejection head control device, the generation timing of noise caused by the first timing pulse and the generation timing of noise caused by the second timing pulse are deviated, so that these noises are superimposed. Can be prevented. For this reason, the bad influence resulting from noise can be prevented.

In the liquid ejection head control apparatus, it is preferable that the drive signal generation unit repeatedly generates the first drive signal and the second drive signal with the certain period as a repeating unit.
According to such a liquid ejection head control device, the first drive signal and the second drive signal can be easily generated.

In this liquid ejection head control device, the drive signal generation unit includes data indicating the voltage of the first drive signal in the certain period and data indicating the voltage of the second drive signal in the certain period. A drive signal voltage data memory is stored for each update cycle, and data indicating the voltage of the first drive signal and data indicating the voltage of the second drive signal are read for each update cycle, and the first drive is performed. The timing pulse generator generates data and the second driving signal, and the timing pulse generator indicates data indicating the generation state of the first timing pulse in the certain period and the generation state of the second timing pulse in the certain period. A timing pulse generation data memory for storing data for each update cycle, and data indicating a generation state of the first timing pulse; and Data indicating a generation state of the second timing pulse reading for each said update period, it is preferable to generate the first timing pulse and said second timing pulses.
According to such a liquid ejection head control device, the first timing pulse and the second timing pulse can be generated in synchronization with the first drive signal and the second drive signal.

In this liquid ejection head control device, the signal applying unit updates first selection data for selecting the first waveform unit at a timing defined by the first timing pulse. An update unit, a first switch for controlling application of the first drive signal to the element based on the first selection data, and second selection data for selecting the second waveform unit, It is preferable to include a second selection data update unit that updates at a timing defined by a timing pulse, and a second switch that controls application of the second drive signal to the element based on the second selection data.
According to such a liquid ejection head control device, the first waveform portion and the second waveform portion can be easily applied to the element.

It will also be clarified that the next liquid ejection head control device can be realized.
That is, (A) a liquid discharge head having at least an element that performs an operation for discharging liquid, and controls the liquid discharge head that changes the volume of the pressure chamber connected to the nozzle by the operation of the element. The liquid ejection head control device includes (B) a first waveform unit that starts from a reference voltage and returns to the reference voltage after undergoing a voltage change of a pattern determined according to an operation to be performed by the element. Then, another discharge change part that changes the voltage to a contraction voltage corresponding to the pressure chamber in the contracted state to discharge the liquid, and the other change part for discharge are generated, and the contraction voltage is generated. A first drive signal having a plurality of first waveform portions that undergo a voltage change of a pattern including other portions to be maintained, and an operation to be performed by the element starting from the reference voltage. A second waveform portion that returns to the reference voltage after undergoing a voltage change of the pattern formed, and a discharge changing portion that changes the voltage to a contraction voltage corresponding to a contracted pressure chamber in order to discharge the liquid; A second drive signal having a plurality of second waveform portions that are generated following the change portion for ejection and undergo a voltage change of a pattern including the portion that maintains the contraction voltage, and is simultaneously generated in a certain period; And (C) a first timing pulse indicating the generation start timing of the first waveform section corresponding to each of the plurality of first waveform sections. And a plurality of second timing pulses indicating the generation start timing of the second waveform portion corresponding to each of the second waveform portions. The first timing pulse corresponding to another first waveform portion generated next to a certain first waveform portion is a part of a voltage change pattern of the second waveform portion, The first portion corresponding to another second waveform portion generated after a certain second waveform portion is generated within a period in which the change portion for returning the voltage to the reference voltage is generated after the liquid is discharged. 2 timing pulses within a part of the voltage change pattern of any one of the first waveform parts, and another change part for returning the voltage to the reference voltage after the liquid is discharged is generated. A timing pulse generator to be generated; and (D) one of the first waveform section and the second waveform section based on a timing defined by one of the first timing pulse and the second timing pulse. Applied to the element A signal applying unit that operates the element in accordance with a voltage change pattern included in any one of the above, and (E) the drive signal generating unit is configured to provide a voltage of the first drive signal in the certain period. And a drive signal voltage data memory for storing data indicating the voltage of the second drive signal in the certain period for each update period, and data indicating the voltage of the first drive signal and the second Data indicating the voltage of the drive signal is read at each update period, and the first drive signal and the second drive signal are generated. (F) The timing pulse generator is configured to generate the first drive signal and the second drive signal. A timing pulse generator that stores data indicating the generation state of the first timing pulse and data indicating the generation state of the second timing pulse in the certain period for each update period. A data memory for reading out the data indicating the generation state of the first timing pulse and the data indicating the generation state of the second timing pulse at each update period, and reading out the first timing pulse and the second timing pulse; When the first timing pulse corresponding to the Nth (N is an integer greater than or equal to 2) first waveform portion is generated within a period during which the change portion for returning to the reference voltage is generated. The second timing pulse corresponding to the Nth second waveform portion is generated during a period in which a certain portion is generated in the reference voltage on the second drive signal side, or the Nth (N is 2 When the second timing pulse corresponding to the second waveform portion (which is an integer above) is generated within a period in which another change portion for returning to the reference voltage is generated, the Nth first A first timing pulse corresponding to a shape portion is generated during a period in which a constant portion is generated with the reference voltage on the first drive signal side, and (G) the signal applying unit includes the first waveform portion. A first selection data update unit that updates first selection data for selection at a timing defined by the first timing pulse, and application of the first drive signal to the element based on the first selection data A second switch that controls the second selection data for selecting the second waveform section at a timing defined by the second timing pulse, and the second selection data. And (H) a change portion for returning to the reference voltage is generated following the portion for maintaining the contraction voltage. Unit The absolute value of the voltage change amount per time is determined to be smaller than the absolute value of the voltage change amount per unit time in the discharge change portion, and (I) the other change portion for returning to the reference voltage is: The absolute value of the voltage change amount per unit time that is generated following the other portion that maintains the contraction voltage is determined to be smaller than the absolute value of the voltage change amount per unit time in the other change portion for discharge. It is also clarified that (J) the control device for the liquid discharge head can be realized.
According to such a control apparatus for the liquid ejection head, almost all of the effects described above can be obtained, and therefore the object of the present invention can be achieved most effectively.

It will also be clarified that the following liquid ejection head control method can be realized.
That is, (A) a method of controlling a liquid ejection head having an element that performs at least an operation for ejecting liquid, and (B) a pattern determined in accordance with an operation to be performed by the element starting from a reference voltage A first drive signal having a plurality of first waveform portions that return to the reference voltage after undergoing a voltage change of the voltage, and a voltage change of a pattern determined according to an operation that is started from the reference voltage and is to be performed by the element Generating a second drive signal having a second waveform portion that later returns to the reference voltage simultaneously in a certain period; and (C) generating a plurality of first timing pulses indicating a generation start timing of the first waveform portion. A plurality of the first timing pulses corresponding to each of the one waveform part and the other first waveform part generated next to a certain first waveform part are described with reference to the first timing pulse. Generating a part of the voltage change pattern of the waveform part within a period in which a change part for returning the voltage to the reference voltage after the liquid is discharged is generated; (D) of the second waveform part; Generating a second timing pulse indicating a generation start timing in correspondence with the second waveform portion, and (E) based on a timing defined by one of the first timing pulse and the second timing pulse, A liquid discharge head that performs (E) by applying any one of the first waveform portion and the second waveform portion to the element and operating the element in accordance with a voltage change pattern of the one or the other. It is also revealed that the control method can be realized.

It is also revealed that the following program can be realized.
That is, (A) a program for a control device that controls a liquid ejection head having an element that performs at least an operation for ejecting liquid, and (B) depending on an operation to be performed by the element starting from a reference voltage A first driving signal having a plurality of first waveform portions that return to the reference voltage after undergoing a voltage change of a predetermined pattern, and a pattern determined according to an operation that starts from the reference voltage and is to be performed by the element Generating a second drive signal having a second waveform portion that returns to the reference voltage after undergoing a voltage change in a certain period, and (C) a first timing pulse indicating the generation start timing of the first waveform portion Are generated in correspondence with each of the plurality of first waveform sections, and the first timing pattern corresponding to another first waveform section generated after a certain first waveform section is generated. The second waveform portion is generated within a period during which a change portion for returning the voltage to the reference voltage after the liquid is discharged is generated (D ) Generating a second timing pulse indicating the generation start timing of the second waveform portion in correspondence with the second waveform portion; and (E) defining either one of the first timing pulse and the second timing pulse. One of the first waveform portion and the second waveform portion is applied to the element based on the timing to be operated, and the element is operated in accordance with a voltage change pattern possessed by the one, (F It is also clarified that a program for causing the control device to perform the above can be realized.

=== First Embodiment ===
<About liquid ejection device>
There are various types of liquid ejection devices such as a printing device, a color filter manufacturing device, a display manufacturing device, a semiconductor manufacturing device, and a DNA chip manufacturing device, and it is difficult to describe all of them. Therefore, in this specification, an ink jet printer (hereinafter also simply referred to as a printer) as a printing apparatus and a printing system having the printer will be described as an example. The printing system is a system having at least a printing apparatus and a printing control apparatus that controls the operation of the printing apparatus.

=== Configuration of Printing System 100 ===
First, the printing apparatus will be described together with the printing system 100. Here, FIG. 1 is a diagram illustrating the configuration of the printing system 100. The illustrated printing system 100 includes a printer 1 as a printing apparatus and a computer 110 as a printing control apparatus. Specifically, the printing system 100 includes a printer 1, a computer 110, a display device 120, an input device 130, and a recording / reproducing device 140.

  The printer 1 prints an image on a medium such as paper, cloth, or film. This medium corresponds to an object to which liquid is discharged. In the following description, a sheet S (see FIG. 3), which is a typical medium, will be described as an example. The computer 110 is communicably connected to the printer 1. In order to cause the printer 1 to print an image, the computer 110 outputs print data corresponding to the image to the printer 1. Computer programs such as application programs and printer drivers are installed in the computer 110. The display device 120 has a display. The input device 130 is a keyboard 131 or a mouse 132, for example. The recording / reproducing device 140 is, for example, a flexible disk drive device 141 or a CD-ROM drive device 142.

=== Computer 110 ===
<Configuration of Computer 110>
FIG. 2 is a block diagram illustrating configurations of the computer 110 and the printer 1. First, the configuration of the computer 110 will be briefly described. The computer 110 includes the recording / reproducing device 140 and the host-side controller 111 described above. The recording / reproducing apparatus 140 is communicably connected to the host-side controller 111, and is attached to the housing of the computer 110, for example. The host-side controller 111 performs various controls in the computer 110, and the display device 120 and the input device 130 described above are also connected to be communicable. The host-side controller 111 includes an interface unit 112, a CPU 113, and a memory 114. The interface unit 112 exchanges data with the printer 1. The CPU 113 is an arithmetic processing unit for performing overall control of the computer 110. The memory 114 is used to secure an area for storing a computer program used by the CPU 113, a work area, and the like, and includes a RAM, an EEPROM, a ROM, a magnetic disk device, and the like. As described above, computer programs stored in the memory 114 include application programs and printer drivers. The CPU 113 performs various controls according to the computer program stored in the memory 114.

  The print data is data in a format that can be interpreted by the printer 1, and includes various command data and dot formation data SI (see FIG. 9). The command data is data for instructing the printer 1 to execute a specific operation. The command data includes, for example, command data for instructing paper feed, command data for indicating the carry amount, and command data for instructing paper discharge. The dot formation data SI is data relating to dots formed on the paper S (data such as dot color and size) and is determined for each unit area. Here, the unit area refers to a rectangular area virtually defined on a medium such as the paper S, and the size and shape are determined according to the print resolution. The dot formation data SI in the present embodiment is composed of dot gradation data indicating the size of dots. The size of the dot is determined by the amount of ink (a kind of liquid) to be ejected. For this reason, the dot formation data SI corresponds to ejection amount information indicating the amount of ejected ink. This gradation data is composed of 3-bit data. For example, the dot formation data SI corresponds to data [000] corresponding to no dot (no ink ejection), data [001] corresponding to the formation of the first small dot, and formation of the second small dot. Data [100], data [010] corresponding to the formation of the first medium dot, data [101] regarding the formation of the second medium dot, and data [011] corresponding to the formation of the large dot. Therefore, the printer 1 can form an image with six gradations for one unit area.

=== Printer 1 ===
<About the configuration of the printer 1>
Next, the configuration of the printer 1 will be described. Here, FIG. 3 is a diagram illustrating a configuration of the printer 1 of the present embodiment. In the following description, FIG. 2 is also referred to.

  As shown in FIG. 2, the printer 1 includes a paper transport mechanism 20, a carriage moving mechanism 30, a head unit 40, a detector group 50, a printer-side controller 60, and a drive signal generation circuit 70. In the present embodiment, the printer-side controller 60 and the drive signal generation circuit 70 are provided on a common controller board CTR. The head unit 40 includes a head controller HC and a head 41. In the printer 1, the control target unit, that is, the paper transport mechanism 20, the carriage moving mechanism 30, the head unit 40 (head controller HC, head 41), and the drive signal generation circuit 70 are controlled by the printer-side controller 60. As a result, the printer-side controller 60 prints an image on the paper S based on the print data received from the computer 110. Each detector in the detector group 50 monitors the status in the printer 1. Each detector outputs the detection result to the printer-side controller 60. Upon receiving the detection results from each detector, the printer-side controller 60 controls the control target unit based on the detection results.

<Regarding the paper transport mechanism 20>
The paper transport mechanism 20 corresponds to a medium transport unit that transports a medium. The paper transport mechanism 20 feeds the paper S as a medium to a printable position, or transports the paper S by a predetermined transport amount in the transport direction. This transport direction is a direction that intersects the carriage movement direction described below. For example, as shown in FIG. 3, the paper transport mechanism 20 includes a transport motor 21 and a transport roller 22. The transport motor 21 is a drive source for the transport roller 22. The operation of the carry motor 21 is controlled by the printer-side controller 60.

<About the carriage moving mechanism 30>
The carriage moving mechanism 30 is for moving the carriage CR to which the head unit 40 is attached in the carriage moving direction. The carriage movement direction includes a movement direction from one side to the other side and a movement direction from the other side to the one side. Here, since the head unit 40 has the head 41, the carriage movement direction corresponds to the head movement direction in which the head 41 moves. The carriage moving mechanism 30 corresponds to a head moving unit that moves the head 41 in a predetermined direction. The carriage moving mechanism 30 includes a carriage motor 31, a guide shaft 32, a timing belt 33, a drive pulley 34, and an idler pulley 35. The carriage motor 31 corresponds to a drive source for moving the carriage CR. The operation of the carriage motor 31 is controlled by the printer-side controller 60. A drive pulley 34 is attached to the rotation shaft of the carriage motor 31. The drive pulley 34 is disposed on one end side in the carriage movement direction. An idler pulley 35 is disposed on the other end side in the carriage movement direction on the opposite side to the drive pulley 34. The timing belt 33 is connected to the carriage CR and is spanned between a drive pulley 34 and an idler pulley 35. The guide shaft 32 supports the carriage CR in a movable state. The guide shaft 32 is attached along the carriage movement direction. Accordingly, when the carriage motor 31 operates, the carriage CR moves along the guide shaft 32 in the carriage movement direction.

<About the head unit 40>
The head unit 40 includes a head 41 that ejects ink toward the paper S. The head unit 40 is attached to the carriage CR. And the head 41 which this head unit 40 has is provided in the lower surface of a head case (not shown). The head control unit HC included in the head unit 40 is provided inside the head case. The head controller HC will be described later.

<About the head 41>
FIG. 4A is a cross-sectional view of the head 41. FIG. 4B is an enlarged view for explaining a main part of the head 41. The head 41 is a kind of liquid ejection head that ejects ink, which is a kind of liquid. As shown in FIG. 4A, the head includes a case 411, a flow path unit 412, a piezo element unit 413, and a relay substrate 414. The case 411 is a block-shaped member in which an accommodation chamber 411a for accommodating the piezo element unit 413 is formed. The piezo element unit 413 is attached to each nozzle row, for example.

  As shown in FIG. 4B, the flow path unit 412 is bonded to the flow path forming plate 412a, the elastic plate 412b bonded to one surface of the flow path forming plate 412a, and the other surface of the flow path forming plate 412a. Nozzle plate 412c. The flow path forming plate 412a is made of a silicon wafer, a metal plate, or the like. The flow path forming plate 412a is formed with a groove portion serving as a pressure chamber 412d, a through hole serving as a nozzle communication port 412e, a through port serving as a common ink chamber 412f, and a groove portion serving as an ink supply path 412g. The elastic plate 412b has a support frame 412h and an island portion 412j to which the tip of the piezo element PZT is joined. An elastic region is formed by the elastic film 412i around the island portion 412j.

  The piezo element unit 413 includes a piezo element group 413a, an adhesion substrate 413b, and an element wiring substrate 413c. The piezo element group 413a has a comb shape, and each comb-like portion corresponds to the piezo element PZT. The piezo element group 413a includes a number of piezo elements PZT corresponding to the nozzles Nz. The bonding substrate 413b is a rectangular plate, and the piezoelectric element group 413a is bonded to one surface and the other surface is bonded to the case 411.

  The relay board 414 is a wiring board for electrically connecting the head controller HC and each piezo element PZT to the drive signal generation circuit 70 and the printer-side controller 60. An element wiring board 413 c is connected to the relay board 414. Further, the flexible cable FC shown in FIG. 3 is also electrically connected to the relay board 414. The flexible cable FC is for transmitting a drive signal COM from the drive signal generation circuit 70 and a head control signal from the printer-side controller 60. The wiring provided on the relay substrate 414 includes ground wiring.

  The piezo element PZT is deformed by applying a potential difference between opposing electrodes. In this example, it expands and contracts in the longitudinal direction of the element. The amount of expansion / contraction is determined according to the potential of the piezo element PZT. The potential of the piezo element PZT is determined by an application part (waveform parts SS11 to SS23, which will be described later) in the drive signal COM. Therefore, the piezo element PZT expands and contracts according to the potential given by the applied drive signal COM. When the piezo element PZT expands and contracts, the island portion 412j is pushed toward the pressure chamber 412d or pulled in the opposite direction. That is, the head 41 can be said to change the volume of the pressure chamber 412d communicating with the nozzle Nz by the operation of the piezo element PZT. At this time, since the elastic film 412i around the island portion is deformed, ink can be efficiently discharged from the nozzle Nz. Such a piezo element PZT is an element that is charged and discharged by the drive signal COM, and corresponds to an element that performs an operation for ejecting ink.

  When the piezo element PZT is used for the head 41, the amount of ink ejected or the like depending on the waveform of the applied drive pulses (for example, the first drive pulse PS1 to the sixth drive pulse PS6; see FIG. 12) Various speeds can be controlled. Further, the ink can be prevented from thickening by causing the meniscus (the free surface of the ink exposed by the nozzles Nz) to vibrate without discharging the ink.

<Regarding the detector group 50>
The detector group 50 is for monitoring the status of the printer 1. This detector group includes, for example, a linear encoder 51 shown in FIG. The linear encoder 51 is for detecting the position of the carriage CR (head 41) in the carriage movement direction. For example, the linear encoder 51 outputs an encoder signal that rises to H level each time the carriage CR moves a distance (25.4 / 180 mm) corresponding to 180 dpi. In addition to this, the detector group includes a rotary encoder for detecting the rotation amount of the transport roller 22 and a paper detector for detecting the presence or absence of the paper S (none is shown).

<About the printer-side controller 60>
The printer-side controller 60 controls the printer 1. As shown in FIG. 2, the printer-side controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a control unit 64. The interface unit 61 exchanges data with the computer 110 which is an external device. The CPU 62 is an arithmetic processing unit for performing overall control of the printer 1. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and is configured by a storage element such as a RAM, an EEPROM, or a ROM. Then, the CPU 62 controls each control target unit according to the computer program stored in the memory 63. For example, the CPU 62 controls the paper transport mechanism 20 and the carriage moving mechanism 30 via the control unit 64.

  Further, the CPU 62 generates a signal for defining the latch timing based on the encoder signal output from the linear encoder 51. For example, when the print resolution is 720 dpi, a signal for defining the latch timing is generated by multiplying the encoder signal by four. Then, the CPU 62 outputs a latch pulse at a timing defined by this signal. That is, the latch signal LAT is switched to the H level at this timing. The latch pulse has, for example, a rectangular waveform having a logic voltage (for example, 3.3V, 5V) and a generation period of about 500 ns.

  Further, the CPU 62 outputs a head control signal for controlling the operation of the head 41 to the head control unit HC, or outputs a drive signal COM (first drive signal COM_A, second drive signal COM_B, see FIG. 12). A control signal for generation is output to the drive signal generation circuit 70. For example, as shown in FIG. 9, the head control signal includes a clock CLK, dot formation data SI, a latch signal LAT, a first change signal CH_A, and a second change signal CH_B. The latch signal LAT has the aforementioned latch pulse, and the first change signal CH_A and the second change signal CH_B have a change pulse. These latch pulses and change pulses correspond to timing pulses for defining the timing at which the drive signal COM is applied to the piezo element PZT (described later). For this reason, the printer-side controller 60 corresponds to a timing pulse generation unit.

  In addition, the printer-side controller 60 uses such a head control signal to cooperate with the head control unit HC to drive the drive signal COM (specifically, the waveform units SS11 to SS13 included in the first drive signal COM_A, Each waveform section SS21 to SS23) included in the second drive signal COM_B can be selectively applied to the piezo element PZT. For this reason, the printer-side controller 60, the drive signal generation circuit 70, and the head controller HC constitute a control device for the head 41.

<Regarding DAC Value and Timing Signal Generation Data>
The control signal for generating the drive signal COM is, for example, a DAC value. This DAC value is data (voltage information) for determining the voltage of the drive signal COM output from the first drive signal generation unit 70A and the second drive signal generation unit 70B (see FIG. 6) of the drive signal generation circuit 70. ). The contents of this control signal are updated every very short update cycle. For example, it is updated every update cycle specified by a clock of 24 MHz. The waveforms of the first drive signal COM_A and the second drive signal COM_B are determined by this DAC value. For this reason, the DAC value corresponds to waveform generation information. As the DAC value in the present embodiment, a first DAC value as waveform generation information for the first drive signal COM_A and a second DAC value as waveform generation information for the second drive signal are defined.

  FIG. 5 is a conceptual diagram for explaining the output of the DAC value and the output of the head control signal. A partial area of the memory 63 included in the printer-side controller 60 is used as a drive signal voltage data memory, and stores a first DAC value and a second DAC value. In the example of FIG. 5, the memory 63 includes a first DAC value storage unit 63a for storing the first DAC value for each update cycle, and a second DAC value storage unit 63b for storing the second DAC value for each update cycle. And function as a drive signal voltage data memory. Each of these storage units 63a and 63b has a plurality of 10-bit registers corresponding to the number of update cycles. In the example of FIG. 5, one square represents one register. Ten registers arranged in the vertical direction indicate a 10-bit first DAC value (first DAC value storage unit 63a) and a 10-bit second DAC value (second DAC value storage unit 63b) in a certain update cycle. ing. These first DAC value and second DAC value are specified by, for example, a pointer P that moves every update cycle. Then, the first DAC value stored in the designated area (address) is output to the first waveform generation circuit 71A, and the second DAC value is output to the second waveform generation circuit 71B.

  The other part of the memory 63 is used as a timing pulse generation data memory 63c and stores generation data related to the latch signal LAT, the first change signal CH_A, and the second change signal CH_B. In addition, the generation data of the end timing signal WVE having an end pulse that defines the generation end timing of the drive signal COM is also stored. In this example, the timing pulse generation data memory 63c has twelve registers for one update period. A plurality of 12 registers are provided corresponding to the update cycle. Thereby, 12 types of signals can be generated in parallel. When generating each signal, the data stored in the area (address) designated by the pointer P is read out in the same manner as the drive signal voltage data memory (storage units 63a and 63b). Here, when the data stored in the register is “0”, the signal becomes L level. On the other hand, when the stored data is “1”, the signal becomes H level. Therefore, a pulse is generated over a period of data “1”. Therefore, data stored in each register corresponds to voltage information of each signal. Further, the generation data of each signal stored in the generation data memory for timing pulse is stored at the same update cycle as the first DAC value and the second DAC value.

  As described above, in the printer 1, the first DAC value and the second DAC value, and the generation data for the timing pulse (latch pulse, first change pulse, second change pulse) are arranged in the common memory 63 with the same update cycle. Stored. Since the printer-side controller 60 reads out data at the timing defined by this update cycle and generates each signal, the printer-side controller 60 easily generates a drive signal COM and a timing pulse that are repeatedly generated every printing period. be able to. Further, the drive signal COM and the timing pulse can be easily synchronized.

  In the present embodiment, since the clock for defining the update period is 24 MHz, the first DAC value and the second DAC value are read about every 0.04 μs. One printing period T is about 140 μs, for example. For this reason, even if the margin is anticipated, it can be said that a printing period T of about 200 μs is sufficient. Therefore, the total capacity of the drive signal voltage data memory (storage units 63a and 63b) and the timing pulse generation data memory 63c is determined in consideration of these conditions.

<About the drive signal generation circuit 70>
FIG. 6 is a block diagram for explaining the configuration of the drive signal generation circuit 70. FIG. 7 is a diagram for explaining the configuration of the first waveform generation circuit 71A and the second waveform generation circuit 71B that the drive signal generation circuit 70 has. FIG. 8 is a diagram for explaining the configuration of the first current amplification circuit 72A and the second current amplification circuit 72B. In FIGS. 7 and 8, the configurations of the second waveform generation circuit 71B and the second current amplification circuit 72B are indicated by parenthesized symbols.

  The drive signal generation circuit 70 generates a drive signal COM that is commonly used for each piezo element PZT, and corresponds to a drive signal generation unit. The drive signal generation circuit 70 simultaneously generates a plurality of types of drive signals COM over a certain period. In the present embodiment, the first drive signal COM_A and the second drive signal COM_B are generated simultaneously over the printing period T. Therefore, the drive signal generation circuit 70 includes a first drive signal generation unit 70A that generates the first drive signal COM_A and a second drive signal generation unit 70B that generates the second drive signal COM_B. Hereinafter, the first drive signal generator 70A and the second drive signal generator 70B will be described.

  The first drive signal generation unit 70A generates a first waveform generation circuit 71A that generates a signal having a voltage corresponding to the first DAC value (first waveform generation information), and the current of the signal generated by the first waveform generation circuit 71A. A first current amplification circuit 72A for amplification is included. In addition, the second drive signal generation unit 70B generates a voltage signal corresponding to the second DAC value (second waveform generation information), and a current of the signal generated by the second waveform generation circuit 71B and the second waveform generation circuit 71B. Has a second current amplifier circuit 72B. Here, the first waveform generation circuit 71A generates a signal having a desired waveform based on the first DAC value. The second waveform generation circuit 71B generates another desired waveform signal based on the second DAC value. The first current amplification circuit 72A amplifies the current of a signal having a desired waveform and outputs it as a first drive signal COM_A. The second current amplification circuit 72B amplifies the current of a signal having another desired waveform and outputs it as a second drive signal COM_B. The first waveform generation circuit 71A and the second waveform generation circuit 71B have the same configuration, and the first current amplification circuit 72A and the second current amplification circuit 72B have the same configuration. For this reason, the following description is mainly given to the first drive signal generation unit 70A, that is, the first waveform generation circuit 71A and the first current amplification circuit 72A.

<Regarding First Waveform Generation Circuit 71A>
As shown in FIG. 7, the first waveform generation circuit 71A includes a digital-analog converter 711A (D / A converter) and a voltage amplification circuit 712A. The digital-analog converter 711A is an electric circuit that outputs a voltage signal corresponding to the first DAC value. The first DAC value is information for designating a voltage (hereinafter also referred to as an output voltage) to be output from the voltage amplification circuit 712A. As described above, the first DAC value is read from the memory 63 and output by the CPU 62. In the present embodiment, the first DAC value is composed of 10-bit data.

  The voltage amplification circuit 712A amplifies the output voltage from the digital-analog converter 711A to a voltage suitable for the operation of the piezo element PZT. In the voltage amplification circuit 712A of this embodiment, the output voltage from the digital-analog converter 711A is amplified to a maximum of 40 and several volts. The amplified output voltage is output to the first current amplification circuit 72A as the control signal S_Tr1 and the control signal S_Tr2. These control signal S_Tr1 and control signal S_Tr2 are drive signals COM_A ′ before current amplification, and correspond to signals having a desired waveform. The control signal S_Tr1 and the control signal S_Tr2 have the same waveform.

<Regarding First Current Amplifier 72A>
The first current amplifier circuit 72A is a circuit for supplying a sufficient current so that the plurality of piezo elements PZT can operate without any trouble. The first current amplification circuit 72A shown in FIG. 8 is configured by a first transistor pair 721A that operates in accordance with a change in the voltage of the first drive signal COM_A. The first transistor pair 721A includes two transistors connected in a complementary manner. Specifically, it is composed of an NPN transistor Tr1 and a PNP transistor Tr2 whose emitter terminals are connected to each other. The NPN transistor Tr1 is a transistor that operates when the voltage of the drive signal COM rises. The NPN transistor Tr1 has a collector connected to the power supply and an emitter connected to the output signal line of the first drive signal COM_A. The PNP transistor Tr2 is a transistor that operates when the voltage of the drive signal COM drops. The PNP transistor Tr2 has a collector connected to the ground and an emitter connected to the output signal line of the first drive signal COM_A. The operation of the first current amplification circuit 72A, that is, the first transistor pair 721A is controlled by a signal COM_A ′ (control signal S_Tr1, control signal S_Tr2) output from the first waveform generation circuit 71A. Therefore, the first drive signal COM_A output from the first current amplification circuit 72A is a signal having a waveform that follows the desired waveform.

<Regarding Second Drive Signal Generation Unit 70B>
Next, the second drive signal generation unit 70B will be briefly described. As described above, the configuration of the second waveform generation circuit 71B is the same as the configuration of the first waveform generation circuit 71A, and the configuration of the second current amplification circuit 72B is the same as the configuration of the first current amplification circuit 72A. . That is, the second waveform generation circuit 71B includes a digital-analog converter 711B and a voltage amplification circuit 712B. The second current amplifier circuit 72B includes a second transistor pair 721B that generates heat as the voltage of the second drive signal COM_B changes. The second transistor pair 721B includes an NPN transistor Tr1 and a PNP transistor Tr2 whose emitter terminals are connected to each other. That is, the second transistor pair 721B is also constituted by a complementary transistor pair.

<About Outline of Generated Drive Signal COM>
Here, an outline of the first drive signal COM_A and the second drive signal COM_B generated by the drive signal generation circuit 70 will be described. In this description, reference is made to FIG. The first drive signal COM_A and the second drive signal COM_B are repeatedly generated with the printing period T as a repeating unit. Therefore, the printing period T corresponds to a certain period for simultaneously generating the first drive signal COM_A and the second drive signal COM_B.

  The first drive signal COM_A has a waveform section SS11 generated in the period T11, a waveform section SS12 generated in the period T12, and a waveform section SS13 generated in the period T13. These waveform sections SS11 to SS13 form a first waveform section included in the first drive signal COM_A. Each waveform section SS11 to SS13 has a drive pulse for causing the piezo element PZT to perform a predetermined operation. That is, the waveform section SS11 has a first drive pulse PS1, and the waveform section SS12 has a second drive pulse PS2. The waveform section SS13 has a third drive pulse PS3. The second drive signal COM_B has a waveform section SS21 generated in the period T21, a waveform section SS22 generated in the period T22, and a waveform section SS23 generated in the period T23. These waveform portions SS21 to SS23 constitute a second waveform portion included in the second drive signal COM_B. Each of the waveform sections SS21 to SS23 also has a drive pulse for causing the piezo element PZT to perform a predetermined operation. That is, the waveform section SS21 has a fourth drive pulse PS4, and the waveform section SS22 has a fifth drive pulse PS5. The waveform section SS23 has a sixth drive pulse PS6.

  Here, the fourth drive pulse PS4 is a fine vibration pulse for displacing the meniscus to such an extent that ink is not ejected. The drive pulses other than the fourth drive pulse PS4 correspond to ejection pulses that cause the piezo element PZT to perform an ejection operation for ejecting ink. These drive signals COM_A and COM_B will be described in detail later.

<About the head controller HC>
Next, the head controller HC will be described. FIG. 9 is a diagram for explaining the configuration of the head controller HC. The head controller HC controls ink ejection using six types of dot formation data SI. That is, the head control unit HC corresponds to a signal application unit, and the waveform units SS11 to SS13 included in the first drive signal COM_A are timings defined by a latch pulse or a first change pulse (corresponding to a first timing pulse). And the waveform portions SS21 to SS23 included in the second drive signal COM_B are selectively applied at a timing defined by a latch pulse or a second change pulse (corresponding to a second timing pulse). . That is, the head control unit HC performs the waveform drive (the waveform parts SS11 to SS13) included in the first drive signal COM_A and the second drive based on the timing defined by one of the first timing pulse and the second timing pulse. Any one of the waveform parts (waveform parts SS21 to SS23) included in the signal COM_B is applied to the piezo element PZT. Thereby, the piezo element PZT is operated, and ink is ejected and the meniscus is vibrated finely.

  As shown in FIG. 9, the head controller HC includes a first shift register 81A, a second shift register 81B, a third shift register 81C, a first latch circuit 82A, a second latch circuit 82B, It has a latch circuit 82C, a control logic 83, a decoder 84, a first switch 85A, and a second switch 85B. In the head controller HC, each part excluding the control logic 83, that is, the shift register 81, the latch circuit 82, the decoder 84, the first switch 85A, and the second switch 85B are provided for each piezo element PZT.

  In the first shift register 81A, the second shift register 81B, and the third shift register 81C, the dot formation data SI from the printer-side controller 60 is set. That is, the middle bit of the dot formation data SI is set in the first shift register 81A, and the lower bit of the dot formation data SI is set in the second shift register 81B. Then, the upper bits of the dot formation data SI are set in the third shift register 81C. Here, the dot formation data SI supplied through the same signal line is set in the first shift register 81A and the second shift register 81B at a timing defined by the clock CLK. On the other hand, the dot formation data SI supplied through the other signal lines is set in the third shift register 81C at a timing defined by the clock CLK.

  The first latch circuit 82A, the second latch circuit 82B, and the third latch circuit 82C latch the dot formation data SI set in the first shift register 81A, the second shift register 81B, and the third shift register 81C. To do. That is, the first latch circuit 82A latches the dot formation data SI set in the first shift register 81A. The second latch circuit 82B latches the dot formation data SI set in the second shift register 81B, and the third latch circuit 82C latches the dot formation data SI set in the third shift register 81C. By being latched by the first latch circuit 82 </ b> A to the third latch circuit 82 </ b> C, the dot formation data SI is set for each nozzle Nz and input to the decoder 84.

  The control logic 83 stores switch operation information for determining the operation of the first switch 85A and switch operation information for determining the operation of the second switch 85B. The switch operation information is determined for each gradation. In the present embodiment, since the dot formation data SI indicates six gradations, six types of switch operation information q0 to q5 are used for the first switch 85A, and six types of switch operation information q6 to q2 are used for the second switch 85B. q11 is used.

  Specifically, the switch operation information q0 to q11 is as follows. That is, as the switch operation information q0 to q5 for the first switch 85A, the switch operation information q0 corresponding to the non-formation of dots (dot formation data SI [000]) and the formation of the first small dots (dot formation data SI) [001]), switch operation information q2 corresponding to second small dot formation (dot formation data SI [100]), and first medium dot formation (dot formation data SI [010]. )), Switch operation information q4 corresponding to the second medium dot formation (dot formation data SI [101]), and large dot formation (dot formation data SI [011]). Switch operation information q5 is prepared. The switch operation information q6 to q11 for the second switch 85B includes switch operation information q6 corresponding to the non-formation of dots, switch operation information q7 corresponding to the formation of the first small dots, and the second small dots. Switch operation information q8 corresponding to the formation, switch operation information q9 corresponding to the formation of the first medium dot, switch operation information q10 corresponding to the formation of the second medium dot, and switch operation information corresponding to the formation of the large dot q11 is prepared.

  The control logic 83 outputs these switch operation information q0 to q11. The contents of the switch operation information q0 to q11 are the timing specified by the latch pulse of the latch signal LAT, the timing specified by the first change pulse of the first change signal CH_A, and the second of the second change signal CH_B. It is updated at the timing specified by the change pulse. FIG. 10 is a diagram for explaining the configuration of the control logic 83. As shown in FIG. 10, the control logic 83 includes a plurality of registers RG that can store 1-bit data. Each register RG is configured by, for example, a D-FF (delay flip flop) circuit. Each register RG stores data constituting each bit of the switch operation information q0 to q11. The switch operation information q0 to q11 is sent from the printer-side controller 60, similarly to the dot formation data SI.

  For convenience of explanation, in FIG. 10, each register RG is arranged in a matrix of four in the column direction (vertical direction) and twelve in the row direction (horizontal direction). The four registers RG belonging to the same column are grouped, and the registers RG of the same group are connected to the same multiplexer (MX0 to MX11). In this example, 12 groups are defined.

  These groups correspond to the switch operation information q0 to q11, respectively. For example, the register RG connected to the multiplexer MX0 stores data of each bit (corresponding to selection data) constituting the switch operation information q0. The register RG connected to the multiplexer MX5 stores data of each bit constituting the switch operation information q5, and the register RG connected to the multiplexer MX11 stores data of each bit constituting the switch operation information q11. Remember.

  In each group of registers RG, the register RG arranged at the top of the figure stores data used in the first period in the printing cycle T. That is, the register RG arranged at the top of the group connected to the multiplexers MX0 to MX5 stores data used in the period T11. Then, the register RG arranged at the top of the group connected to the multiplexers MX6 to MX11 stores data used in the period T21. In addition, the register RG arranged in the second row from the top stores data used in the second period in the printing cycle. That is, data used in the period T12 and the period T22 is stored. Similarly, the register RG arranged in the third row from the top stores data used in the third period (period T13, period T23) in the printing cycle. Therefore, the control logic 83 can store data up to the fourth period.

  Summarizing the above, each register RG included in the control logic 83 includes the type of the corresponding drive signal COM (first drive signal COM_A, second drive signal COM_B), and corresponding dot formation data SI (data [000] to data [000]. 011]), switch operation information q0 to q11 determined by each factor of the corresponding waveform section (waveform sections SS11 to SS23) can be stored. Since the switch operation information q0 to q11 is selection data for selecting the waveform sections SS11 to SS23, each register RG corresponds to a selection data storage section.

  Then, the multiplexers MX0 to MX11 output the data stored in these registers RG. At that time, the output data is updated at a timing defined by a latch pulse or a change pulse. For example, the multiplexers MX0 to MX5 switch the register RG according to the count value output from the first counter CTA. The first counter CTA is reset at the rising edge of the latch pulse, and is counted up at the rising edge of the first change pulse included in the first change signal CH_A. For this reason, when the latch pulse is input, the data for the period T11 is output as the switch operation information q0 to q5 from the multiplexers MX0 to MX5. When the first first change pulse is input, the data for the period T12 is output from the multiplexers MX0 to MX5, and when the second first change pulse is input, the period from the multiplexers MX0 to MX5 is the period. Data for T13 is output. Similarly, the multiplexers MX6 to MX11 switch the register RG according to the count value output from the second counter CTB. The second counter CTB is reset at the rising edge of the latch pulse, and is counted up at the rising edge of the second change pulse included in the second change signal CH_B. For this reason, when the latch pulse is input, the data for the period T21 is output from the multiplexers MX6 to MX11 as the switch operation information q6 to q11. When the first second change pulse is input, the data for the period T22 is output from the multiplexers MX6 to MX11, and when the second second change pulse is input, the period from the multiplexers MX6 to MX11 is output. Data for T23 is output.

  As can be seen from the above description, the control logic 83 uses the first selection data (switch operation information q0 to q5) for selecting the first waveform section (waveform sections SS11 to SS13) included in the first drive signal COM_A. This corresponds to a first data updating unit that updates at a timing defined by a first timing pulse (latch pulse, first change pulse). In addition, the control logic 83 receives second selection data (switch operation information q6 to q11) for selecting the second waveform portion (waveform portions SS21 to SS23) included in the second drive signal COM_B as the second timing pulse (latch). This also corresponds to a second data update unit that updates at a timing defined by a pulse, a second change pulse). The specific contents of the selection data q0 to q11 will be described later.

  The decoder 84 selects the switch operation information q0 to q11 output from the control logic 83 according to the dot formation data SI latched by the latch circuit 82, and selects the selected switch operation information as the first switch 85A and the second switch 85A. Output to each of the switches 85B. The first switch 85A is a switch that operates according to the switch operation information q0 to q5, and controls application of the first drive signal COM_A to the piezo element PZT. The second switch 85B is a switch that operates according to the switch operation information q6 to q11, and controls application of the second drive signal COM_B to the piezo element PZT. These switches 85A and 85B apply the corresponding drive signals COM_A and COM_B to the piezo element PZT over the period of data “1”. Further, the corresponding drive signals COM_A and COM_B are not applied to the piezo element PZT during the period of data “0”.

=== Printing operation ===
<About printing operation>
Next, a printing operation performed by the printer 1 for printing on the paper S will be described. Here, FIG. 11 is a flowchart for explaining the printing operation of the printer 1. As shown in FIG. 11, in the printer 1, as a series of printing operations, a printing command receiving operation (S10), a paper feeding operation (S20), a dot forming operation (S30), a conveying operation (S40), and a paper discharge determination ( S50), a paper discharge operation (S60), and a print end determination (S70) are performed. This printing operation is performed by the CPU 62 included in the printer-side controller 60. That is, the CPU 62 operates according to the computer program stored in the memory 63 and executes these operations. Therefore, this computer program has a code for executing each operation.

  In the print command receiving operation, the printer-side controller 60 receives a print command from the computer 110 via the interface unit 61. This print command is included in print data transmitted from the computer 110. The paper feeding operation is an operation of moving the paper S to be printed and positioning it at a print start position (so-called cueing position). In this paper feeding operation, the printer-side controller 60 rotates a paper feeding roller (not shown) and sends the paper S to be printed to the transport roller 22. Subsequently, the printer-side controller 60 rotates the transport roller 22 to position the paper S sent from the paper feed roller at the print start position. The dot formation operation is an operation in which dots are formed on the paper S by intermittently ejecting ink from the head 41 moving in the carriage movement direction. The printer-side controller 60 drives the carriage motor 31 to move the carriage CR in the carriage movement direction. Further, the printer-side controller 60 ejects ink from the head 41 (nozzle Nz) based on the dot formation data SI while the carriage CR is moving. When the ink discharged from the head 41 lands on the paper S, dots are formed on the paper S as described above. The dot forming operation will be described in detail later. The transport operation is an operation of moving the paper S relative to the head 41 along the transport direction. The printer-side controller 60 rotates the transport roller 22 to transport the paper S in the transport direction. By this transport operation, the head 41 can form dots at positions different from the positions of the dots formed by the previous dot formation operation. The paper discharge determination is a process for determining whether or not to discharge the paper S being printed. This determination is made based on the presence or absence of print data. That is, the printer-side controller 60 determines whether or not there is print data for the paper S being printed, and determines that the paper is not discharged if the print data remains. In this case, the printer-side controller 60 alternately repeats the dot formation operation and the conveyance operation until there is no print data, and gradually prints an image composed of dots on the paper S. The printer-side controller 60 determines that the paper is discharged if there is no print data, and rotates the paper discharge roller 25 to discharge the printed paper S to the outside. Note that whether or not to discharge paper may be determined based on a paper discharge command included in the print data. The print end determination is a determination as to whether or not to continue printing. In this determination, the printer-side controller 60 determines whether there is print data. If printing is to be performed on the next paper S, the paper feeding operation for the next paper S is performed. On the other hand, if printing is not performed on the next sheet S, the printing operation is terminated.

=== Dot Forming Operation ===
<Overview of dot formation operation>
In the dot forming operation, the first waveform portion (SS11 to SS13) included in the first drive signal COM_A is selected at each timing defined by the latch pulse or the first change pulse (that is, the first timing pulse), and necessary. The waveform portion is applied to the piezo element PZT. Similarly, the second waveform section (SS21 to SS23) included in the second drive signal COM_A is selected at each timing defined by the latch pulse or the second change pulse (that is, the second timing pulse), and the necessary waveform section is selected. Is applied to the piezo element PZT. The selection of the waveform portion is performed based on the switch operation information q0 to q11 whose contents are updated at the timing of each pulse described above. The switch operation information q0 to q11 is updated through the multiplexers MX0 to MX11, for example.

  In such a configuration, noise may occur in each of the drive signals COM_A and COM_B at the timing of generating each timing pulse. For example, when the timing of the change pulse arrives while a current is flowing toward many piezo elements PZT, the current that has flowed until then is stopped at that timing. In the relationship between the DAC value (or the control signals S_Tr1 and S_Tr2) and the change pulse, a margin is provided so that the current is stopped before the change pulse timing. However, in the actual drive signals COM_A and COM_B, waveform distortion may occur when the number of piezo elements PZT to be charged and discharged becomes large and the amount of current becomes very large. This is because the piezo element PZT can be regarded as a capacitor. For example, when the number of piezo elements PZT to be charged / discharged increases, the combined capacitance of the piezo elements PZT increases accordingly, and waveform distortion is likely to occur. Due to this distortion, current may flow through the piezo element PZT even at the timing of the change pulse.

  As described above, when the timing of the change pulse arrives while the current is flowing through the piezo element PZT and the application of the drive signal COM is suddenly stopped, there is a possibility that the ground potential may change due to a sudden change in the current. is there. If the ground can be formed sufficiently wide, the potential change can be suppressed, but the area that can be secured as the ground in the limited wiring space of the head 41 is limited. Then, this change in ground potential appears as noise in each of the drive signals COM_A and COM_B.

  In the printer 1, the multiplexers MX0 to MX11 perform a switching operation at each timing specified by each timing pulse. Then, switching noise at that time may appear in each of the drive signals COM_A and COM_B.

  A problem arises when such noise occurs during the period from the start of generation of drive pulses to the time when ink is ejected. The waveforms (voltage change patterns) of the drive pulses PS1 to PS6 described above are determined based on the operation performed by the piezo element PZT. In particular, the waveform in the period until ink is ejected is for filling the pressure chamber 412d with ink, or for rapidly contracting the pressure chamber 412d to eject ink in the pressure chamber 412d from the nozzle Nz. is there. Therefore, if noise occurs during this period, the piezo element PZT may operate unexpectedly, which may adversely affect ink ejection. For example, there is a possibility that the amount of ejected ink deviates from the normal amount, or the flight direction of the ink deviates from the normal direction.

  In view of such circumstances, in the printer 1, at least one of the second and subsequent first timing pulses is based on the voltage after the ink is ejected in the waveform portions SS21 to SS23 on the second drive signal COM_B side. The change part for returning to the voltage is generated within a period in which the change part is generated. For the second and subsequent second timing pulses, at least one of the waveform portions SS11 to SS13 on the first drive signal COM_A side is generated as a change portion for returning the voltage to the reference voltage after ink ejection. Has been generated within the period. As a result, even if noise occurs in each of the drive signals COM_A and COM_B at the timing of the first timing pulse and the second timing pulse, the influence on ink ejection can be prevented. As a result, adverse effects due to noise can be reduced. Further, the degree of freedom increases with respect to the period in which the timing pulse can be generated. Details will be described below.

<About generated drive signals and timing signals>
FIG. 12 is a diagram illustrating the first drive signal COM_A, the second drive signal COM_B, the latch signal LAT, the first change signal CH_A, and the second change signal CH_B generated by the dot formation operation.

  In this dot formation operation, the first drive signal generator 70A generates the first drive signal COM_A, and the second drive signal generator 70B generates the second drive signal COM_B. The generation of the first drive signal COM_A and the second drive signal COM_B is performed in synchronization with the generation of the latch pulse included in the latch signal LAT. That is, the CPU 62 starts reading the first DAC value and the second DAC value from the memory 63 (drive signal voltage data memory) based on a signal for defining the latch timing (for example, at the rising edge timing). The read first DAC value and second DAC value are output to the digital-analog converter 711A of the first drive signal generation unit 70A and the digital-analog converter 711B of the second drive signal generation unit 70B. Accordingly, the first drive signal COM_A is generated by the first drive signal generation unit 70A, and the second drive signal COM_B is generated by the second drive signal generation unit 70B.

  The CPU 62 of the printer-side controller 60 starts reading timing pulse generation data from the memory 63 (timing pulse generation data memory) based on a signal for defining the latch timing. Thereby, a latch signal (latch pulse), a first change signal CH_A (first change pulse), and a second change signal CH_B (second change pulse) are generated.

<Details of Drive Signals COM_A and COM_B>
The first drive signal COM_A is generated in the waveform section SS11 generated in the first period T11 in the printing period T (repetition period), the waveform section SS12 generated in the second period T12, and the third period T13. And a waveform portion SS13. Further, the second drive signal COM_B includes a waveform section SS21 generated in the first period T21 in the printing period T, a waveform section SS22 generated in the second period T22, and a waveform generated in the third period T23. Part SS23. The waveform section SS11 included in the first drive signal COM_A has a first drive pulse PS1. The waveform section SS12 has a second drive pulse PS2, and the waveform section SS13 has a third drive pulse PS3. The waveform section SS21 included in the second drive signal COM_B has a fourth drive pulse PS4. The waveform section SS22 has a fifth drive pulse PS5, and the waveform section SS23 has a sixth drive pulse PS6.

  These drive pulses PS1 to PS6 are voltage change patterns for driving the piezo element PZT to perform a desired operation. The start voltage and the end voltage of these drive pulses PS1 to PS6 are the same, and these voltages are reference voltages. Accordingly, the waveform sections SS11 to SS23 having these drive pulses PS1 to PS6 start from the reference voltage, and after a voltage change of a pattern determined according to the operation to be performed by the piezo element PZT, return to the reference voltage. A signal.

  In the present embodiment, when the drive pulses PS1 to PS6 are applied, the piezo element PZT expands and contracts according to the voltage waveform of the applied drive pulse and displaces the island portion 412j. The volume of the pressure chamber 412d changes with the displacement of the island portion 412j. For example, the volume of the pressure chamber 412d at the reference voltage is set as the reference volume. When a voltage portion higher than the reference voltage in a certain drive pulse is applied to the piezo element PZT, the piezo element PZT contracts in the longitudinal direction of the element in a direction to separate the island portion 412j from the pressure chamber 412d. Displace. Along with this, the pressure chamber 412d expands more than the reference volume. When a voltage lower than the reference voltage in a certain drive pulse is applied to the piezo element PZT, the piezo element PZT extends in the longitudinal direction of the element and displaces the island portion 412j toward the pressure chamber 412d. Along with this, the pressure chamber 412d contracts from the reference volume. When the rising portion of the voltage in the drive pulse is applied to the piezo element PZT, the pressure chamber 412d expands according to the change in voltage, and when the falling portion of the voltage is applied to the piezo element PZT, the pressure chamber 412d Shrink in response to voltage changes. In addition, when a constant voltage portion higher than the reference voltage is applied to the piezo element PZT, the pressure chamber 412d maintains an expanded state corresponding to the voltage. When a constant voltage portion lower than the reference voltage is applied to the piezo element PZT, the pressure chamber 412d maintains a contracted state corresponding to the voltage.

<Regarding the fourth drive pulse PS4>
Among the drive pulses PS1 to PS6, the fourth drive pulse PS4 is a fine vibration pulse. When the fourth drive pulse PS4 is applied to the piezo element PZT, a weak pressure fluctuation that does not eject ink occurs in the ink in the pressure chamber 412d, and the meniscus is vibrated slightly. Specifically, the fourth drive pulse PS4 has a trapezoidal shape, and when a voltage rising portion (portion inclined obliquely upward to the right) is applied to the piezo element PZT, the voltage change of this portion is changed. Along with this, the piezo element PZT contracts. As a result, the pressure chamber 412d slightly expands from the reference volume. It is considered that the meniscus is slightly pulled toward the pressure chamber 412d with this expansion. Next, a constant voltage portion in the fourth drive pulse PS4 is applied to the piezo element PZT. During this period, the contracted state of the piezo element PZT is maintained, and the meniscus is considered to vibrate freely. Next, a voltage drop portion (portion inclined obliquely to the right) in the fourth drive pulse PS4 is applied to the piezo element PZT. During this period, the contracted piezo element PZT extends to the reference state. As a result, the pressure chamber 412d contracts to the reference volume, and the meniscus is thought to be pushed out slightly toward the outside of the head 41.

  Due to the displacement of the meniscus, the thickened ink that tends to exist in the vicinity of the nozzle Nz is agitated, and the ink state can be maintained well. The fourth drive pulse PS4 is a simple one that causes the piezo element PZT to expand and contract the pressure chamber 412d once. For this reason, the generation period T21a of the fourth drive pulse PS4 is determined to be shorter than the other drive pulses.

<About the fifth drive pulse PS5>
The fifth drive pulse PS5 is a first small dot pulse. That is, the fifth drive pulse PS5 is for ejecting an amount of ink suitable for forming the first small dot. In the present embodiment, when the fifth drive pulse PS5 is applied to the piezo element PZT, about 1.5 pL of ink is ejected from the nozzle Nz. The fifth drive pulse PS5 will be described. In the fifth drive pulse PS5, the pressure chamber 412d is expanded from the reference volume to the maximum volume by increasing the voltage from the reference voltage to the maximum voltage. The expanded state is maintained by maintaining this maximum voltage. Next, the fifth drive pulse PS5 is lowered to the reference voltage and then raised to the maximum voltage. As a result, the pressure chamber 412d contracts to the reference volume and expands to the maximum volume. Next, the voltage is rapidly lowered to the lowest voltage. As a result, the pressure chamber 412d contracts to the minimum volume. Then, ink is ejected from the nozzle Nz. Thereafter, the fifth drive pulse PS5 maintains the voltage at the minimum voltage and raises it to the reference voltage. As a result, the pressure chamber 412d is expanded to the reference volume after the minimum volume is maintained.

  In the fifth drive pulse PS5, the expanded state is maintained after the pressure chamber 412d is expanded from the reference volume to the maximum volume, but the maintenance time is set longer than the other drive pulses. This is intended to fill the pressure chamber 412d in an expanded state with ink. In addition, after maintaining the expanded state, the respective operations of contracting the pressure chamber 412d to the reference volume, expanding to the maximum volume, and contracting to the minimum volume are continuously performed. Then, the position of the meniscus is controlled by each operation of contraction to the reference volume and expansion to the maximum volume. Further, the ink is ejected from the nozzle Nz by contraction to the minimum volume. Accordingly, in the fifth drive pulse PS5, the portion where the voltage is lowered from the highest voltage to the lowest voltage corresponds to the changed portion for ejection. The minimum voltage corresponds to the contraction voltage corresponding to the pressure chamber in the contracted state. By performing such an operation, an extremely small amount of ink of about 1.5 pL is ejected from the nozzle Nz.

Although the meniscus is largely displaced by the reaction of the ink ejection, the fifth drive pulse PS5 increases the voltage from the minimum voltage to the reference voltage, and expands the pressure chamber 412d from the minimum volume to the reference volume, thereby reducing the meniscus displacement. ing. That is, it is considered that the ink pressure in the pressure chamber 412d is higher than the atmospheric pressure while the meniscus is displaced to the outside of the nozzle Nz (paper S side). For this reason, when the pressure chamber 412d is expanded at the timing when the meniscus is displaced to the outside of the nozzle Nz, the ink pressure in the pressure chamber 412d is somewhat lowered, and the displacement of the meniscus can be suppressed. Therefore, in the fifth drive pulse PS5, the constant portion at the minimum voltage is a constant voltage portion for maintaining the contraction voltage, and can be said to be a portion for determining the expansion start timing of the pressure chamber 412d after ink ejection. Further, the portion where the voltage is increased from the lowest voltage to the reference voltage corresponds to a changing portion for returning to the reference voltage. Then, the gradient in this change portion, that is, the absolute value of the voltage change amount per unit time is smaller than the absolute value of the gradient in the change portion for discharge.
In order to perform such control, the generation period T22a of the fifth drive pulse PS5 is set to the longest time.

<Regarding third drive pulse PS3>
The third drive pulse PS3 is a second small dot pulse. That is, the third drive pulse PS3 ejects an amount of ink suitable for forming the second small dot. In the present embodiment, when the third drive pulse PS3 is applied to the piezo element PZT, about 3 pL of ink is ejected from the nozzle Nz. In the third drive pulse PS3, the voltage is increased from the reference voltage to the maximum voltage, and then the maximum voltage is maintained. As a result, the pressure chamber 412d is expanded from the reference volume to the maximum volume and maintained in the expanded state. Thereafter, the third drive pulse PS3 lowers its voltage to the reference voltage, then increases it to the intermediate voltage, and further decreases it to the lowest voltage. By this series of voltage changes, the pressure chamber 412d is contracted to the reference volume, then expanded to the intermediate volume, and further contracted to the minimum volume. Here, the contraction to the reference volume and the expansion to the intermediate volume in the pressure chamber 412d are performed to adjust the position of the meniscus, similarly to the fifth drive pulse PS5. The intermediate volume is a volume that is larger than the reference volume and smaller than the maximum volume. The contraction to the minimum volume is performed to eject ink. Thereafter, the voltage of the third drive pulse PS3 is maintained at the minimum voltage and is increased to the reference voltage. As a result, the pressure chamber 412d is expanded to the reference volume after the minimum volume is maintained. As a result, the meniscus displacement after ink ejection is reduced.

  In the third drive pulse PS3, the portion that decreases from the intermediate voltage to the lowest voltage corresponds to the changed portion for ejection. The minimum voltage corresponds to the contraction voltage corresponding to the pressure chamber 412d in the contracted state, and the constant portion at the minimum voltage corresponds to the constant voltage portion that maintains the contraction voltage. The constant portion at the minimum voltage is also a portion for determining the expansion start timing of the pressure chamber 412d after ink ejection. Further, the portion where the voltage is increased from the lowest voltage to the reference voltage corresponds to a changing portion for returning to the reference voltage. The absolute value of the gradient in this changing portion is smaller than the absolute value of the gradient in the changing portion for discharge. The generation period T13a of the third drive pulse PS3 is set to the second longest time.

<About drive pulses PS1, PS2, PS6>
The remaining drive pulses, that is, the first drive pulse PS1, the second drive pulse PS2, and the sixth drive pulse PS6 are medium dot pulses. When one of these drive pulses is applied to the piezo element PZT, about 7 pL of ink is ejected from the nozzle Nz. When two are applied to the piezo element PZT, a total of about 14 pL of ink is ejected from the nozzle Nz, and when three are applied to the piezo element PZT, a total of about 21 pL of ink is ejected from the nozzle Nz. . In this embodiment, one of these drive pulses is applied to the piezo element PZT when the first medium dot is formed. Specifically, the second drive pulse PS2 is applied to the piezo element PZT. Further, when forming the second medium dot, two of these drive pulses are applied to the piezo element PZT. Specifically, the second drive pulse PS2 and the sixth drive pulse PS6 are applied to the piezo element PZT. Further, when forming a large dot, these three drive pulses PS1, PS2 and PS6 are applied to the piezo element PZT.

  These drive pulses PS1, PS2 and PS6 all have the same voltage waveform (voltage change pattern). Therefore, it can be said that the piezo element PZT performs the same operation. The first drive pulse PS1 will be described as an example. Even in the first drive pulse PS1, the maximum voltage is maintained after the voltage is increased from the reference voltage to the maximum voltage. Thereby, the pressure chamber 412d is expanded from the reference volume to the maximum volume, and the expanded state is maintained. Thereafter, the voltage of the first drive pulse PS1 is lowered to the lowest voltage. As a result, the pressure chamber 412d is contracted to the minimum volume, and ink is ejected from the nozzle Nz. Thereafter, the voltage of the first drive pulse PS1 is maintained at the minimum voltage and is increased to the reference voltage. As a result, the pressure chamber 412d expands to the reference volume after maintaining the minimum volume.

  As can be seen from this description, a portion of the first drive pulse PS1 that changes from the highest voltage to the lowest voltage corresponds to a changed portion for ejection. The minimum voltage corresponds to the contraction voltage corresponding to the pressure chamber 412d in the contracted state, and the constant part of the minimum voltage corresponds to the part that maintains the contraction voltage. The constant portion at the minimum voltage is also a portion for determining the expansion start timing of the pressure chamber 412d after ink ejection. Further, the portion where the voltage is increased from the lowest voltage to the reference voltage corresponds to a changing portion for returning to the reference voltage. The absolute value of the gradient in the changed portion is smaller than the absolute value of the gradient in the changed portion for discharge.

  The generation periods T11a, T12a, and T23a of these drive pulses PS1, PS2, and PS6 are all the same, slightly shorter than the generation period T13a of the third drive pulse PS3, and longer than the generation period T21a of the fourth drive pulse PS4. Is set.

<Regarding the operation of applying each waveform portion to the piezo element PZT>
Next, the operation of applying the waveform portions SS11 to SS23 to the piezo element PZT based on the switch operation information will be described. FIG. 13A is a diagram illustrating specific contents of the switch operation information q0 to q11. FIG. 13B is a diagram for explaining the applied drive pulse and the ink ejection amount for each dot gradation (for each dot formation data SI).

  As described above, the printer 1 can form dots with six types of dot gradations. That is, no dot (dot formation data SI [000]), first small dot formation (dot formation data SI [001]), second small dot formation (dot formation data SI [100]), first medium dot (Dot formation data SI [010]), second medium dot formation (dot formation data SI [101]), and large dot formation (dot formation data SI [011]) Can control the gradation.

  In this case, the switch operation information q0 to q11 is determined as follows. That is, the switch operation information q0 corresponding to the dot formation data SI without dots is the data [000], and the switch operation information q6 is the data [100]. The switch operation information q1 corresponding to the dot formation data SI of the first small dot is data [000], and the switch operation information q7 is data [010]. The switch operation information q2 corresponding to the dot formation data SI of the second small dot is data [001], and the switch operation information q8 is data [000]. The switch operation information q3 corresponding to the dot formation data SI for the first medium dot is data [010], and the switch operation information q9 is data [000]. The switch operation information q4 corresponding to the dot formation data SI for the second medium dot is data [010], and the switch operation information q10 is data [001]. The switch operation information q5 corresponding to the dot formation data SI for large dots is data [110], and the switch operation information q11 is data [001].

  Thereby, when there is no dot, the waveform portion SS21 of the second drive signal COM_B is applied to the piezo element PZT, and the meniscus is vibrated slightly based on the voltage change pattern of the fourth drive pulse PS4. In the formation of the first small dot, the waveform portion SS22 of the second drive signal COM_B is applied to the piezo element. Then, approximately 1.5 pL of ink is ejected based on the voltage change pattern of the fifth drive pulse PS5. In the formation of the second small dot, the waveform portion SS13 of the first drive signal COM_A is applied to the piezo element PZT, and about 3 pL of ink is ejected based on the voltage change pattern of the third drive pulse PS3. In the formation of the first medium dot, the waveform portion SS12 of the first drive signal COM_A is applied to the piezo element PZT, and about 7 pL of ink is ejected based on the voltage change pattern of the second drive pulse PS2. In the formation of the second medium dot, the waveform portion SS12 of the first drive signal COM_A and the waveform portion SS23 of the second drive signal COM_B are applied to the piezo element PZT, and the voltage change pattern of the second drive pulse PS2 and the sixth drive pulse PS6. Based on this, about 14 pL of ink is ejected. In the formation of large dots, the waveform portion SS11, the waveform portion SS12 of the first drive signal COM_A, and the waveform portion SS23 of the second drive signal COM_B are applied to the piezo element PZT, and the first drive pulse PS1, the second drive pulse PS2, and Based on the voltage change pattern of the sixth drive pulse PS6, about 21 pL of ink is ejected.

=== Timing pulse ===
<About timing pulse>
Here, the timing pulse will be described. As can be seen from the above description, application or non-application of the first drive signal COM_A to the piezo element PZT is selected at the generation timing of the latch pulse and the generation timing of the first change pulse. Therefore, the latch pulse and the first change pulse correspond to a first timing pulse that defines the generation start timing of the first waveform section included in the first drive signal COM_A. Similarly, application or non-application of the second drive signal COM_B to the piezo element PZT is selected at the generation timing of the latch pulse and the generation timing of the second change pulse. For this reason, the latch pulse and the second change pulse correspond to a second timing pulse that defines the generation start timing of the second waveform portion included in the second drive signal COM_B.

  Here, the latch pulse is used for each of the first drive signal COM_A and the second drive signal COM_B, and defines the generation start timing of the waveform parts (waveform parts SS11 and SS21) to be generated first. . And a 1st change pulse prescribes | regulates the production | generation start timing of the 1st waveform part produced | generated after 2nd. In the example of FIG. 12, the first first change pulse defines the generation start timing of the waveform portion SS12 generated second, and the second first change pulse is the waveform portion SS13 generated third. The generation start timing is defined. Therefore, each first change pulse corresponds to a first timing pulse corresponding to another first waveform portion generated next to a certain first waveform portion. Similarly, the second change pulse defines the generation start timing of the second waveform parts (waveform parts SS22 and SS23) generated after the second. Therefore, each second change pulse corresponds to a second timing pulse corresponding to another second waveform portion generated next to a certain second waveform portion.

<About both first change pulses>
FIG. 14 is a diagram for explaining the relationship among the first first change pulse CH_A (1), the first second change pulse CH_B (1), the first drive pulse PS1, and the fifth drive pulse PS5. The first first change pulse CH_A (1) determines the generation start timing of the waveform section SS12 (corresponding to the second first waveform section) included in the first drive signal COM_A. Then, considering that the first timing pulse is composed of a latch pulse and each first change pulse, the first first change pulse CH_A (1) corresponds to the second first timing pulse. On the other hand, the first second change pulse CH_B (1) determines the generation start timing of the waveform section SS22 (corresponding to the second second waveform section) included in the second drive signal COM_B. The first second change pulse CH_B (1) corresponds to the second second timing pulse, similarly to the first first change pulse CH_A (1).

  Since the first first change pulse CH_A (1) determines the generation start timing of the waveform section SS12, the second drive included in the waveform section SS12 from the generation end timing of the first drive pulse PS1 included in the waveform section SS11. It can be said that it may be generated during the period X1 until the generation start timing of the pulse PS2. In the present embodiment, the first first change pulse CH_A (1) is applied to the overlap period Z1 within the period X1 and the period Y1 in which a constant portion is generated with the highest voltage in the fifth drive pulse PS5. Is generated. Here, the constant portion of the maximum voltage in the fifth drive pulse PS5 is a portion generated before ink is ejected. For this reason, there is a possibility that the ejection of ink by the fifth drive pulse PS5 may be disturbed. From this point of view, it may be considered as an unfavorable timing. However, in the fifth drive pulse PS5 of the present embodiment, the generation time of the constant portion at this maximum voltage is set sufficiently longer than the corresponding portions in the other drive pulses. In addition, the generation timing of the first first change pulse CH_A (1) is determined immediately after the start of generation of a constant portion at the maximum voltage. As a result, even if the waveform of the fifth drive pulse PS5 is disturbed due to the first first change pulse CH_A (1), the disturbance is within a period in which a constant portion is generated at the maximum voltage. It seems to converge. For this reason, even if the first first change pulse CH_A (1) is generated at this timing, it can be said that there is no difficulty in ejecting ink by the fifth drive pulse PS5.

<Regarding the first second change pulse CH_B (1)>
Since the first second change pulse CH_B (1) determines the generation start timing of the waveform section SS22, the fifth drive included in the waveform section SS22 from the generation end timing of the fourth drive pulse PS4 included in the waveform section SS21. It can be said that it may be generated during the period Y2 until the generation start timing of the pulse PS5. In the present embodiment, the first second change pulse CH_B (1) is overlapped with the period X2 within the period Y2 and the period X2 during which the voltage is increased from the lowest voltage to the reference voltage in the first drive pulse PS1. Has been generated. Hereinafter, the reason for this will be described.

  FIG. 15A is a diagram schematically illustrating the relationship between the waveform of the first drive pulse PS1 and the displacement state of the meniscus by the first drive pulse PS1. FIG. 15B is a diagram for explaining a displacement state of the meniscus M. FIG. 15A, the vertical axis indicates the voltage of the first drive signal COM_A, the horizontal axis indicates time, and in the lower stage, the vertical axis indicates the position of the meniscus M, and the horizontal axis indicates time. Note that the upper time and the lower time are synchronized. In the lower part, the line segment indicates the position of the top of the meniscus M. This line segment is obtained based on simulation. In FIG. 15A, the value “0” on the vertical axis means the steady state of the meniscus M. Specifically, as shown by a solid line in FIG. 15B, it means that the meniscus M is located at the opening of the nozzle Nz. The sign “+” means that the top of the meniscus M is located outside the opening edge of the nozzle Nz (for example, the sheet S side). For example, as shown by a dotted line in FIG. 15B, it means a state in which the top of the meniscus M protrudes outward from the opening edge of the nozzle Nz. Therefore, as the value of + increases, the top of the meniscus M is in a state of being separated from the opening edge of the nozzle Nz. On the other hand, the symbol “−” means a state in which the top of the meniscus M is drawn to the nozzle communication port 412e side (pressure chamber 412d side) from the opening edge of the nozzle Nz, as indicated by a one-dot chain line in FIG. 15B. Therefore, the larger the value of −, the more the top of the meniscus M is drawn toward the nozzle communication port 412e.

  As shown in FIG. 15A, at the timing t1 when the voltage drops from the highest voltage of the first drive pulse PS1, the top of the meniscus M is in a state of being pulled slightly from the opening edge of the nozzle Nz. As the first drive pulse PS1 drops to the lowest voltage, the top of the meniscus M moves outside the opening edge of the nozzle Nz. This is presumably because the ink in the pressure chamber 412d was pressurized as the pressure chamber 412d contracted. In this example, the meniscus M continues to move outward even after the timing t2 when the first drive pulse PS1 is lowered to the lowest voltage. This is considered to be influenced by the responsiveness of the piezo element PZT and the elasticity of the elastic plate 412b.

  The movement of the meniscus M to the outside ends at the timing t3 during which the first drive pulse PS1 maintains the minimum voltage, and thereafter moves to the nozzle communication port 412e side. This timing t3 is considered to be the ink ejection timing. That is, as indicated by a dotted line in FIG. 15B, it is considered that the meniscus M extends in a columnar shape as the pressure chamber 412d contracts. Then, it is considered that the columnar part is cut off in the middle, the part on the tip side is ejected as droplet-like ink, and the root part becomes a new meniscus M. It is considered that the base side portion vigorously returns to the nozzle Nz side due to the reaction when separated from the tip side, and is drawn to the nozzle communication port 412e side from the opening edge of the nozzle Nz. Thereafter, at the timing t4 when the drawn meniscus M again moves outside the head 41, the first drive pulse PS1 starts to increase from the lowest voltage. Then, at the timing t6, the first drive pulse PS1 returns to the reference voltage.

  As described above, the period in which the voltage is raised from the lowest voltage to the reference voltage in the first drive pulse PS1 corresponds to the generation period of the changed portion for returning the voltage to the reference voltage after ink (liquid) is ejected. . In the first drive pulse PS1, since the portion where the voltage is changed from the lowest voltage to the reference voltage is generated after the period Δt3 has elapsed from the ink ejection timing (t3), the displacement of the meniscus M is quickly suppressed. be able to. That is, since the pressure chamber 412d is expanded as the voltage of the first drive pulse PS1 increases, the outward movement of the meniscus M can be suppressed.

  In this embodiment, as shown also in FIG. 14, the first second change pulse CH_B (1) is generated in a part for returning the voltage from the lowest voltage to the reference voltage in the first drive pulse PS1, that is, It is generated during a period from timing t4 to timing t6. The period (t4-t6) is a period after the ink ejection timing t3 as described above. For this reason, even if the noise Ns caused by the first second change pulse CH_B (1) is generated in the first drive signal COM_A (first drive pulse PS1), it is difficult to affect ink ejection. Therefore, adverse effects due to this noise can be reduced. In addition, the absolute value of the gradient of the portion for returning the voltage to the reference voltage is smaller than the absolute value of the gradient of the change portion (portion generated at t1-t2) for ejecting ink. For this reason, even if the waveform of the portion for returning the voltage to the voltage is disturbed by noise, it is possible to prevent a problem that ink is ejected.

  By the way, in this embodiment, the first second change pulse CH_B (1) is generated almost in the middle of the period from timing t4 to timing t6 (timing t5). Even if it is generated at this timing, it is a matter of course that the effect of reducing adverse effects due to noise can be obtained. If a higher effect is to be obtained, the voltage of the first second change pulse CH_B (1) is changed from the timing t4 to the timing t5, that is, from the lowest voltage to the reference voltage in the first drive pulse PS1. It is preferable to produce in the first half of the part to be made. This is because the momentum of the meniscus M is considered to be greater than the generation period of the second half part in the generation period of the first half part. And since the momentum of the meniscus M is large, even if the waveform of the first drive pulse PS1 is disturbed by noise, it is considered that the influence is unlikely to occur. Therefore, adverse effects due to noise can be reliably reduced. From this point of view, it can be said that the generation start timing of the first second change pulse CH_B (1) is best aligned with the timing of the voltage increase start from the lowest voltage (ie, timing t4).

<About the second change pulse>
FIG. 16 is a diagram for explaining the relationship among the second first change pulse CH_A (2), the second second change pulse CH_B (2), and the fifth drive pulse PS5. The second first change pulse CH_A (2) determines the generation start timing of the waveform section SS13 (corresponding to the third first waveform section) included in the first drive signal COM_A. This corresponds to one timing. On the other hand, the second second change pulse CH_B (2) determines the generation start timing of the waveform section SS23 (corresponding to the third second waveform section) included in the second drive signal COM_B. This corresponds to the second timing pulse.

  Since the second first change pulse CH_A (2) determines the generation start timing of the waveform section SS13, the period X3 from the generation end timing of the second drive pulse PS2 to the generation start timing of the third drive pulse PS3. It can be said that it should just be generated during the period. In the present embodiment, the second first change pulse CH_A (2) is within the period X3, and the period during which the portion where the voltage is increased from the lowest voltage to the reference voltage in the fifth drive pulse PS5 is generated. It is generated in the overlap period Z3 with Y3. In this example, the period Y3 corresponds to a generation period of a changed portion for returning the voltage to the reference voltage after ink (liquid) is ejected. The period Y3 is generated during the generation period of the period X3. For this reason, the period Y3 coincides with the overlap period Z3.

  By determining the generation timing of the second first change pulse CH_A (2) in this way, it is possible to reduce adverse effects due to noise. This is due to the same reason as that of the first second change pulse CH_B (1). Briefly, the second first change pulse CH_A (2) is generated during a period (t9-t10) in which the fifth drive pulse PS5 increases the voltage to the reference voltage after ink ejection. . For this reason, even if noise occurs due to the second first change pulse CH_A (2), it can be made less susceptible to the influence of noise.

  Further, the absolute value of the gradient of the portion where the voltage is increased to the reference voltage is smaller than the absolute value of the gradient of the changing portion (portion generated at t7-t8) for ejecting ink. For this reason, even if the waveform of the portion for returning the voltage to the voltage is disturbed by noise, it is possible to prevent a problem that ink is ejected.

  Since the second second change pulse CH_B (2) determines the generation start timing of the waveform section SS23, the period Y4 from the generation end timing of the fifth drive pulse PS5 to the generation start timing of the sixth drive pulse PS6. It can be said that it should just be generated during the period. In the present embodiment, the second second change pulse CH_B (2) is generated within the overlapping period Z4 of the period Y4 and the period X3.

  By determining the generation timing of the second second change pulse CH_B (2) in this way, adverse effects due to noise can be reduced. That is, the second change pulse CH_B (2) is a reference voltage from the end of generation of the second drive pulse PS2 to the start of generation of the third drive pulse PS3, and the sixth drive from the end of generation of the fifth drive pulse PS5. The reference voltage until generation of the pulse PS6 is generated in the overlap period Z4 with a certain portion. For this reason, even if noise occurs in both drive signals COM_A and COM_B due to the second second change pulse CH_B (2), the noise affects the third drive pulse PS3 and the sixth drive pulse PS6. It becomes difficult to do. As a result, adverse effects due to noise can be reduced.

<Summary>
The first embodiment configured as described above has the following effects.
That is, the printer 1 of the first embodiment includes (A) a drive signal generation circuit 70, (B) a timing pulse generation unit (printer-side controller 60), and (C) a head control unit HC.

  The drive signal generation circuit 70 starts from the reference voltage and undergoes a voltage change of a pattern determined according to the operation to be performed by the piezo element PZT (that is, the drive pulses PS1 to PS3), and then returns to the reference voltage. A first drive signal COM_A having SS13, and a waveform portion that returns to the reference voltage after undergoing a voltage change (drive pulses PS4 to PS6) of a pattern that is determined according to the operation that is started from the reference voltage and is performed by the piezo element PZT. The second drive signal COM_B having SS21 to SS23 is simultaneously generated in the printing period T.

  The timing pulse generation unit outputs a latch pulse indicating generation start timing of the waveform parts SS11 to SS13, the first first change pulse CH_A (1), and the second first change pulse CH_A (2) to the waveform parts SS11 to SS13. Are generated in correspondence with each of the above, and a latch pulse indicating the generation start timing of the waveform parts SS21 to SS23, a first second change pulse CH_B (1), a second second change pulse CH_B (2), A plurality of waveform portions SS21 to SS23 are generated in correspondence with each other.

  Then, the timing pulse generator changes the second first change pulse CH_A (2) corresponding to the waveform section SS13 generated next to the waveform section SS12 from the lowest voltage in the fifth drive pulse PS5 to the reference voltage. It is generated during the generation period of the part. Further, the timing pulse generator changes the first second change pulse CH_B (1) corresponding to the waveform section SS22 generated next to the waveform section SS21 from the lowest voltage in the first drive pulse PS1 to the reference voltage. It is generated during the generation period of the part.

  The head control unit HC has a waveform unit based on the timing defined by either the first timing pulse (latch pulse, each first change pulse) or the second timing pulse (latch pulse, each second change pulse). Any one of SS11 to SS13 and waveform portions SS21 to SS23 is applied to the piezo element PZT, and the piezo element PZT is operated in accordance with the drive pulses PS1 to PS6 included in any one of them.

  In the printer 1, even if noise occurs in the fifth drive pulse PS5 at the timing of the second first change pulse CH_A (2), ink ejection is completed at this timing. As a result, adverse effects due to noise can be reduced. Similarly, even if noise occurs in the first drive pulse PS1 at the timing of the first second change pulse CH_B (1), ink ejection is completed at this timing, so that adverse effects due to noise are reduced. Can do.

  Here, the second first change pulse CH_A (2) corresponds to the third first timing pulse, and defines the generation start timing of the third first waveform section (waveform section SS13). The second second change pulse CH_B (2) corresponds to the third second timing pulse and defines the generation start timing of the third waveform section (waveform section SS23). The second first change pulse CH_A (2) is generated during the voltage increase period of the fifth drive pulse PS5, whereas the second second change pulse CH_B (2) is the fifth drive pulse PS5. The reference voltage from the generation end timing to the generation start timing of the sixth drive pulse PS6 is generated in a certain period. That is, the change pulses CH_A (2) and CH_B (2) are generated at different times. For this reason, it is possible to reliably prevent noise caused by the change pulses CH_A (2) and CH_B (2) from overlapping each other.

  Similarly, the first first change pulse CH_A (1) corresponds to the second first timing pulse, and defines the generation start timing of the second first waveform section (waveform section SS12). The first second change pulse CH_B (1) corresponds to the second second timing pulse and defines the generation start timing of the second waveform section (waveform section SS22). The first second change pulse CH_B (1) is generated during the voltage rise period of the first drive pulse PS1, whereas the first first change pulse CH_A (1) is the first drive pulse PS1. The reference voltage from the generation end timing to the generation start timing of the second drive pulse PS2 is generated in a certain period. For this reason, it is possible to reliably prevent noise caused by the change pulses CH_A (1) and CH_B (1) from overlapping each other.

  In short, in this printer 1, when the first timing pulse corresponding to the Nth (N is an integer of 2 or more) first waveform portion is generated within the period in which the change portion for returning to the reference voltage is generated. The second timing pulse corresponding to the Nth second waveform portion is generated during a period in which a certain portion is generated with the reference voltage on the second drive signal side. Further, when the second timing pulse corresponding to the Nth second waveform portion is generated within a period in which another change portion for returning to the reference voltage is generated, it corresponds to the Nth first waveform portion. The first timing pulse is generated during a period in which a certain portion is generated with the reference voltage on the first drive signal side. This prevents noise from being superimposed and prevents the piezo element PZT from operating unexpectedly.

  In the printer 1 of the first embodiment, at least one of the drive pulses PS1 to PS3 included in each of the waveform sections SS11 to SS13 has a generation period of the drive pulses PS4 to PS6 included in each of the waveform sections SS21 to SS23. Different from at least one generation period. Specifically, as shown in FIG. 12, the generation period T11a of the first drive pulse PS1 and the generation period T12a of the second drive pulse PS2 are different from the generation period T21a of the fourth drive pulse PS4. It is also different from the generation period T22a of the pulse PS5. In the case of a drive signal including a plurality of drive pulses having different generation periods as described above, aligning the generation start timing of the waveform portion with the first drive signal COM_A and the second drive signal COM_B unnecessarily increases the print period T. Therefore, it is not preferable. And the malfunction resulting from noise can be suppressed by comprising like this embodiment. For this reason, even if it is the limited printing period T, a several waveform part can be produced | generated efficiently, suppressing the influence of noise.

  Further, in the printer 1, a drive pulse (drive pulse PS1 to PS3, PS5, PS6) for ejecting different amounts of ink and a drive pulse (drive pulse PS4) for slightly vibrating the meniscus are used as the first drive signal. It is included in COM_A and the second drive signal COM_B. For this reason, it is possible to cause the head 41 to perform various operations even during the limited printing period T.

=== About Other Embodiments ===
The above-described embodiment is mainly described with respect to the printing system 100 including the printer 1 as a liquid ejection apparatus, but the disclosure includes a liquid ejection method, a liquid ejection system, and the like. In addition, the disclosure of a control device for controlling the liquid ejection head and the disclosure of a program and code for controlling the liquid ejection device and the control device are also included. Further, this embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About drive signal>
In the first embodiment described above, the first drive signal COM_A has three waveform portions SS11 to S13, and the second drive signal COM_B also has three waveform portions SS21 to S23. However, the number of waveform portions is not limited to this number. In the printer 1 of the first embodiment, the generation periods of the paired waveform portions (SS11 and SS21, SS12 and SS22, SS13 and SS23) are slightly different, but not significantly different. For this reason, the Nth first timing pulse and the Nth second timing pulse are in a paired relationship. That is, the generation timings are closest to each other. However, it is not limited to this configuration. For example, a certain 2nd waveform part may be defined in the production | generation period for two of the 1st waveform part. In such a case, if the first timing pulse and the second timing pulse in which the generation timings are closest to each other are in the above-described relationship, the same effect is obtained.

  Further, in the first embodiment, the configuration in which two types of drive signals, the first drive signal COM_A and the second drive signal COM_B, are generated simultaneously over the printing period T is exemplified. However, there are two types of drive signals COM. It is not limited. Even if there are three or more types, the same can be implemented. Further, even when the first drive signal COM_A has two types of waveform portions and the second drive signal COM_B has one type of waveform portions, the same operation is performed depending on the waveform of the drive pulse included in the second drive signal COM_B. can do.

<Elements that operate to eject ink>
The piezoelectric element PZT according to the first embodiment expands the pressure chamber 412d by increasing the potential and contracts the pressure chamber 412d by decreasing the potential. Regarding this piezo element, an element that contracts the pressure chamber 412d by increasing the potential and expands the pressure chamber 412d by decreasing the potential may be used. In addition, it is considered that the same effect can be obtained if an element that operates to eject ink is affected by noise.

<About other application examples>
In the above-described embodiment, the printer 1 has been described as the liquid ejecting apparatus. However, the present invention is not limited to this. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, liquid vaporizer, organic EL manufacturing apparatus (particularly polymer EL manufacturing apparatus), display manufacturing apparatus, film formation The same technology as that of the present embodiment may be applied to various liquid ejection devices to which inkjet technology such as a device and a DNA chip manufacturing device is applied. These methods and manufacturing methods are also within the scope of application.

1 is a diagram illustrating a configuration of a printing system. It is a block diagram explaining the structure of a computer and a printer. First, the configuration of the computer will be briefly described. FIG. 2 is a diagram illustrating a configuration of a printer. FIG. 4A is a cross-sectional view of the head. FIG. 4B is an enlarged view for explaining a main part of the head. It is a conceptual diagram for demonstrating the output of a DAC value, and the output of a head control signal. It is a block diagram for demonstrating the structure of a drive signal generation circuit. It is a figure for demonstrating the structure of the 1st waveform generation circuit which a drive signal generation circuit has, and a 2nd waveform generation circuit. It is a figure for demonstrating the structure of a 1st current amplifier circuit and a 2nd current amplifier circuit. It is a figure for demonstrating the structure of a head control part. It is a figure for demonstrating the structure of a control logic. 3 is a flowchart illustrating a printing operation of a printer. It is a figure which shows the 1st drive signal, 2nd drive signal, latch signal, 1st change signal, and 2nd change signal which are produced | generated by dot formation operation | movement. FIG. 13A is a diagram illustrating specific contents of the switch operation information q0 to q11. FIG. 13B is a diagram for explaining the applied drive pulse and the ink ejection amount for each dot gradation. It is a figure explaining the relationship between the 1st 1st change pulse, the 1st 2nd change pulse, the 1st drive pulse, and the 5th drive pulse. FIG. 15A is a diagram schematically illustrating the relationship between the waveform of the first drive pulse and the meniscus displacement state caused by the first drive pulse. FIG. 15B is a diagram for explaining the displacement state of the meniscus. It is a figure explaining the relationship between the 2nd 1st change pulse, the 2nd 2nd change pulse, and the 5th drive pulse.

Explanation of symbols

1 printer, 20 paper transport mechanism, 21 transport motor, 22 transport roller,
30 Carriage moving mechanism, 31 Carriage motor, 32 Guide shaft,
33 timing belt, 34 drive pulley, 35 idler pulley,
40 head units, 41 heads, 411 case, 411a accommodation room,
412 channel unit, 412a channel forming plate, 412b elastic plate,
412c nozzle plate, 412d pressure chamber, 412e nozzle communication port,
412f common ink chamber, 412g ink supply path, 412h support frame,
412i elastic film, 412j island, 413 piezo element unit,
413a piezoelectric element group, 413b bonding substrate, 413c element wiring board,
414 relay board, 50 detector groups, 51 linear encoder,
60 printer-side controller, 61 interface unit, 62 CPU,
63 memory, 64 control unit, 70 drive signal generation circuit,
70A first drive signal generation unit, 71A first waveform generation circuit,
711A digital analog converter, 712A voltage amplification circuit,
72A first current amplification circuit, 721A first transistor pair,
70B second drive signal generation unit, 71B second waveform generation circuit,
711B digital analog converter, 712B voltage amplification circuit,
72B second current amplification circuit, 721B second transistor pair,
81A first shift register, 81B second shift register,
81C third shift register, 82A first latch circuit,
82B second latch circuit, 82C third latch circuit, 83 control logic,
84 decoder, 85A first switch, 85B second switch,
100 printing system, 110 computer, 111 host side controller,
112 interface unit, 113 CPU, 114 memory,
120 display device, 130 input device, 131 keyboard, 132 mouse,
140 recording / reproducing apparatus, 141 flexible disk drive apparatus,
142 CD-ROM drive, S paper, SI dot formation data,
LAT latch signal, CH_A first change signal,
CH_A (1) 1st first change pulse,
CH_A (2) second first change pulse, CH_B second change signal,
CH_B (1) 1st second change pulse,
CH_B (2) 2nd second change pulse, CTR controller board,
HC head controller, RG register, CR carriage,
PZT piezo element, FC flexible cable, COM drive signal,
COM_A first drive signal, SS11 waveform section, SS12 waveform section,
SS13 waveform section, COM_B second drive signal, SS21 waveform section,
SS22 waveform section, SS23 waveform section, PS1 first drive pulse,
PS2 second drive pulse, PS3 third drive pulse, PS4 fourth drive pulse,
PS5 5th drive pulse, PS6 6th drive pulse, Nz nozzle,
S_Tr1 control signal, S_Tr2 control signal,
Tr1 NPN type transistor, Tr2 PNP type transistor,
switch operation information for q0 dot non-formation,
q1 switch operation information for the first small dot,
q2 switch operation information for the second small dot,
q3 switch operation information for the first medium dot,
q4 switch operation information for the second medium dot,
q5 switch operation information for large dots,
q6 Switch operation information for non-dot formation,
q7 Switch operation information for the first small dot,
q8 Switch operation information for the second small dot,
q9 switch operation information for the first medium dot,
q10 switch operation information for the second medium dot,
q11 Switch operation information for large dots

Claims (9)

Controlling the liquid ejection head having at least performing device performs operation for ejecting liquids, a control system for a liquid discharge head,
(A) The liquid discharge head changes the volume of the pressure chamber communicating with the nozzle by the operation of the element,
(B) a first drive signal having a plurality of first waveform portions that return to the reference voltage after undergoing a voltage change of a pattern determined in accordance with an operation to be performed by the element starting from a reference voltage, and the reference voltage Drive signal generation that simultaneously generates a second drive signal having a second waveform portion that returns to the reference voltage after undergoing a voltage change of a pattern determined according to an operation to be performed by the element that is started from And
(C) A plurality of first timing pulses indicating the generation start timing of the first waveform portion are generated corresponding to each of the plurality of first waveform portions, and a second indicating the generation start timing of the second waveform portion. A timing pulse generating unit that generates a timing pulse corresponding to the second waveform unit;
At least one of the first timing pulses corresponding to another first waveform portion generated next to a certain first waveform portion is a part of a voltage change pattern included in any of the second waveform portions. And generating a change portion for returning the voltage to the reference voltage after the liquid is discharged ,
At least one of the second timing pulses corresponding to another second waveform part generated next to a second waveform part is a part of a voltage change pattern of any of the first waveform parts. A timing pulse generator that generates within a period in which another change part for returning the voltage to the reference voltage after the liquid is discharged , and
(D) Based on the timing defined by one of the first timing pulse and the second timing pulse, either the first waveform portion or the second waveform portion is applied to the element, A signal applying unit that operates the element in accordance with a voltage change pattern that either one has,
The second waveform part is generated following the discharge change part for changing the voltage to a contraction voltage corresponding to the pressure chamber in the contracted state in order to discharge the liquid, and the contraction It goes through the voltage change of the pattern including the part that maintains the voltage,
The change part for returning to the reference voltage is generated following the part for maintaining the contraction voltage, and the absolute value of the voltage change amount per unit time is calculated per unit time in the discharge change part. A control device for a liquid discharge head , which is determined to be smaller than the absolute value of the voltage change amount . A control device for a liquid discharge head according to claim 1 ,
The liquid discharge head is
The volume of the pressure chamber communicated with the nozzle is changed by the operation of the element,
The first waveform portion is
A change portion for other discharge that changes the voltage to a contraction voltage corresponding to the pressure chamber in the contracted state in order to discharge the liquid, and the change portion for the other discharge are generated, and the contraction voltage is maintained. It goes through the voltage change of the pattern including other parts,
Other changing parts for returning to the reference voltage are:
A control apparatus for a liquid discharge head, which is generated following the other part for maintaining the contraction voltage. A control device for a liquid ejection head according to claim 2 ,
Other changing parts for returning to the reference voltage are:
An apparatus for controlling a liquid discharge head, wherein an absolute value of a voltage change amount per unit time is set smaller than an absolute value of a voltage change amount per unit time in the other change portion for discharge. A control device for a liquid ejection head according to any one of claims 1 to 3 ,
The timing pulse generator is
When the first timing pulse corresponding to the Nth (N is an integer greater than or equal to 2) first waveform portion is generated within a period in which the change portion for returning to the reference voltage is generated, the Nth A control apparatus for a liquid ejection head, wherein a second timing pulse corresponding to two waveform portions is generated during a period in which a constant portion is generated with the reference voltage on the second drive signal side. A control device for a liquid discharge head according to any one of claims 1 to 4,
The timing pulse generator is
When the second timing pulse corresponding to the Nth (N is an integer greater than or equal to 2) second waveform portion is generated within a period in which another change portion for returning to the reference voltage is generated, the Nth The liquid ejection head control device generates a first timing pulse corresponding to the first waveform portion during a period in which a constant portion is generated by the reference voltage on the first drive signal side. A control device for a liquid ejection head according to any one of claims 1 to 5 ,
The drive signal generator is
A control apparatus for a liquid ejection head, wherein the first drive signal and the second drive signal are repeatedly generated with the certain period as a repetition unit. It is a control apparatus of the liquid discharge head of Claim 6 , Comprising:
The drive signal generator is
A drive signal voltage data memory for storing data indicating the voltage of the first drive signal in the certain period and data indicating the voltage of the second drive signal in the certain period for each update period;
Read the data indicating the voltage of the first drive signal and the data indicating the voltage of the second drive signal for each update period, and generate the first drive signal and the second drive signal,
The timing pulse generator is
A timing pulse generation data memory for storing data indicating the generation state of the first timing pulse in the certain period and data indicating the generation state of the second timing pulse in the certain period for each update period; ,
A liquid ejection head that reads out data indicating the generation state of the first timing pulse and data indicating the generation state of the second timing pulse at each update period to generate the first timing pulse and the second timing pulse. Control device. A control device for a liquid ejection head according to any one of claims 1 to 7 ,
The signal applying unit is
A first selection data updating unit for updating first selection data for selecting the first waveform unit at a timing defined by the first timing pulse;
A first switch for controlling application of the first drive signal to the element based on the first selection data;
A second selection data updating unit for updating second selection data for selecting the second waveform unit at a timing defined by the second timing pulse;
And a second switch that controls application of the second drive signal to the element based on the second selection data. In a method for controlling a liquid ejection head having an element that performs at least an operation for ejecting liquid , the volume of a pressure chamber communicating with a nozzle is changed by the operation of the element.
(B) a first drive signal having a plurality of first waveform portions that return to the reference voltage after undergoing a voltage change of a pattern determined in accordance with an operation to be performed by the element starting from a reference voltage, and the reference voltage and generating simultaneously the second driving signal, a period having a second waveform portion to return to the reference voltage after a voltage change pattern defined according to the operation to be started performed in the element from,
(C) A plurality of first timing pulses indicating the generation start timing of the first waveform portion are generated corresponding to each of the plurality of first waveform portions, and a second indicating the generation start timing of the second waveform portion. Generating a timing pulse corresponding to the second waveform portion,
At least one of the first timing pulses corresponding to another first waveform portion generated next to a certain first waveform portion is a part of a voltage change pattern included in any of the second waveform portions. And generating a change portion for returning the voltage to the reference voltage after the liquid is discharged,
At least one of the second timing pulses corresponding to another second waveform part generated next to a second waveform part is a part of a voltage change pattern of any of the first waveform parts. Generating within a period during which another change portion for returning the voltage to the reference voltage is generated after the liquid is discharged;
( D ) applying one of the first waveform portion and the second waveform portion to the element based on a timing defined by one of the first timing pulse and the second timing pulse; and to operate the device in accordance with any voltage change pattern one has,
Including
The second waveform part is generated following the discharge change part for changing the voltage to a contraction voltage corresponding to the pressure chamber in the contracted state in order to discharge the liquid, and the contraction It goes through the voltage change of the pattern including the part that maintains the voltage,
The change part for returning to the reference voltage is generated following the part for maintaining the contraction voltage, and the absolute value of the voltage change amount per unit time is calculated per unit time in the discharge change part. A method for controlling the liquid ejection head , which is set to be smaller than the absolute value of the voltage change amount .

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