JP4645125B2 - Drive signal generation method, computer program, printing apparatus, and printing system - Google Patents

Description

  The present invention relates to a method for generating a drive signal for driving an element for performing an operation of ejecting ink, a computer program, a printing apparatus, and a printing system.

  As an element for executing the operation of ejecting ink, there is a printing apparatus that has, for example, a piezoelectric element and ejects ink by applying a driving pulse to the piezoelectric element. In this printing apparatus, it is common to use a single drive signal having a plurality of drive pulses at regular intervals. Then, by selectively applying a plurality of drive pulses within a certain period to the piezo element, it is possible to eject a desired amount of ink in a predetermined region. In such a printing apparatus, in order to express gradation more finely, it is necessary to increase the number of drive pulses for ejecting ink in a predetermined area, so that the certain period becomes longer and printing is performed. There was a problem that the speed decreased.

Focusing on this problem, a new type of printing apparatus has been proposed in recent years. In this printing apparatus, a driving pulse can be applied alternatively to a single piezoelectric element from a plurality of original driving signals, and a driving pulse included in each original driving signal is selectively applied to the piezoelectric element. For example, a printing apparatus has been proposed in which a plurality of types of drive pulses with different amounts of ejected ink are divided into two original drive signals and a drive pulse applied to a piezo element is selected (for example, Patent Documents). 1). That is, in two original drive signals having a plurality of drive pulses, the drive pulse applied to the piezo element is selected by switching the original drive signal between the drive pulses adjacent to each original drive signal. A drive signal is generated.
JP 2000-52570 A

  By the way, when two original drive signals are switched to generate one drive signal, the original drive signals are switched between adjacent drive pulses in each original drive signal that should be set to the same voltage. At this time, if the voltage at which the original drive signal is switched differs between the two original drive signals due to the characteristics of the drive signal generation circuit, the voltage changes abruptly at the moment when the original drive signal is switched. When the voltage of the drive signal changes abruptly, ink may be ejected from the piezo element, and the image quality may deteriorate.

  The present invention has been made in view of such a problem, and an object of the present invention is to prevent a voltage from rapidly changing when the original drive signal is switched.

The main invention for achieving the above object is to generate a first original drive signal having a unit signal for defining from the start to the end of operation of an element for executing the operation of ejecting ink based on the drive signal. A step of actually measuring a relationship between an input value and a voltage of the first original drive signal generating unit, and a second original drive signal having a unit signal for defining from the start to the end of the operation of the element. A step of actually measuring a relationship between an input value and a voltage of the original drive signal generation unit; a relationship between an input value and a voltage of the first original drive signal generation unit; an input value and an output of the second original drive signal generation unit; Based on this relationship, the first voltage corresponding to the reference voltage is set so that the reference voltages of the first original drive signal and the second original drive signal are aligned in a predetermined period from the end of the operation to the start of the operation. Original drive signal generator And an input value to the second original drive signal generation unit, and the unit signal of the first original drive signal and the whole unit signal of the second original drive signal on the basis of the reference voltage Obtaining the input value of the first original drive signal generation unit and the input value of the second original drive signal generation unit so that the voltages of the first original drive signal generation unit and the second original drive signal are equal to each other. Generating the first original drive signal and the second original drive signal, respectively, and switching the first original drive signal and the second original drive signal in the predetermined period to generate the drive signal. And a step of generating the drive signal.

  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.

  The characteristics of the first original drive signal generation unit that generates the first original drive signal having a unit signal for defining from the start to the end of the operation of the element for executing the operation of ejecting ink based on the drive signal. A step of measuring, a step of measuring characteristics of a second original drive signal generating unit that generates a second original drive signal having a unit signal for defining from the start of operation of the element to the end of operation, and after the end of the operation And the second original drive signal and the second original drive signal based on the measured result so that the voltages of the first original drive signal and the second original drive signal are aligned in a predetermined period from the start of the operation to the start of the operation. Causing the original drive signal generation unit to generate the first original drive signal and the second original drive signal, respectively, and switching between the first original drive signal and the second original drive signal in the predetermined period A method of generating a drive signal and having the steps of: generating the driving signal.

  According to such a drive signal generation method, the predetermined period for switching between the first original drive signal and the second original drive signal is the voltage between the first original drive signal and the second original drive signal based on the actually measured result. Since the first original drive signal and the second original drive signal are generated so that the first original drive signal and the second original drive signal are switched, the drive signal is generated by switching between the first original drive signal and the second original drive signal. The voltage does not change. For this reason, it is possible to prevent ink from being ejected from the element when the first original drive signal and the second original drive signal are switched. Particularly, the first original drive signal and the second original drive signal in a predetermined period are set to have the same voltage based on the results of actual measurement of the characteristics of the first original drive signal generator and the second original drive signal generator. Since it is generated, a more reliable original drive signal can be generated with high reliability.

In this drive signal generation method, it is preferable that the first original drive signal and the second original drive signal are different.
When the first original drive signal and the second original drive signal are different, it is possible to include unit signals having different ink ejection amounts in each original drive signal. Therefore, it is possible to generate a drive signal capable of realizing a finer gradation without changing the voltage abruptly when the first original drive signal and the second original drive signal are switched. It is possible to form a high-quality image.

In such a drive signal generation method, it is desirable that both can be changed so that the voltage increases or decreases during the predetermined period.
According to such a drive signal generation method, the voltage in the predetermined period can be easily determined according to the actually measured value, regardless of which of the first original drive signal and the second original drive signal is large or small. It is possible to generate the original drive signals so that they are aligned.

In this drive signal generation method, the unit signal is preferably generated based on a voltage in the predetermined period.
According to such a drive signal generation method, even when the voltage in a predetermined period is changed, the unit signal is generated based on the changed voltage, so that the desired amount is not affected by the operation of the element. It is possible to discharge the ink.

In this drive signal generation method, the element operates based on the unit signal based on a voltage output corresponding to periodically inputted numerical information, and the first original drive signal is It is desirable to set the numerical information so that the voltages of the second original drive signals are uniform.
According to such a drive signal generation method, it is possible to easily and appropriately align the voltages simply by setting numerical information so that the voltages of the first original drive signal and the second original drive signal are aligned in a predetermined period. In addition, the first original drive signal and the second original drive signal can be generated.

In this drive signal generation method, it is preferable that the characteristic is a voltage output for the numerical information input to the first original drive signal generation unit and the second original drive signal generation unit.
According to such a drive signal generation method, the voltage output for the numerical information input to the first original drive signal generation unit and the second original drive signal generation unit is measured, and the measured result is On the basis of this, the first original drive signal and the second original drive signal are generated so that the voltages of the first original drive signal and the second original drive signal in the predetermined period are aligned. It is possible to generate the first original drive signal and the second original drive signal so that the voltages at are equal.

In such a drive signal generation method, it is preferable that the numerical information is set such that voltages of the first original drive signal and the second original drive signal in the predetermined period are respectively predetermined voltages.
According to such a drive signal generation method, the voltages of the first original drive signal and the second original drive signal in a predetermined period are aligned so as to be a predetermined voltage, that is, a desired voltage. It will be. For this reason, it is possible to easily align the voltages of a plurality of original drive signals formed by a plurality of original drive signal generators having different characteristics, and the same amount can be used regardless of which original drive signal generator is used. It is possible to discharge the ink.

In the method of generating the drive signal, the first original drive signal and the second original drive signal are such that a voltage of one original drive signal in the predetermined period is a voltage of the other original drive signal in the predetermined period. The numerical information that is input to the original drive signal generation unit that generates the one original drive signal may be set so as to be aligned.
According to such a drive signal generation method, the voltage of the first original drive signal and the second original drive signal in a predetermined period is input to the original drive signal generation unit that generates one of the original drive signals. Since it is arranged by setting numerical information, the setting process is easier compared to the case of setting each piece of numerical information input to the plurality of original drive signal generation units based on the actually measured result.

A first original drive signal generating unit configured to generate a first original drive signal having a unit signal for defining from an operation start to an operation end of an element for performing an operation of ejecting ink based on the drive signal; A step of actually measuring a characteristic, a step of actually measuring a characteristic of a second original drive signal generating unit that generates a second original drive signal having a unit signal for defining from the operation start to the operation end of the element, and the operation Based on the actual measurement result, the first original drive signal generator and the first original drive signal so that the voltages of the first original drive signal and the second original drive signal are aligned in a predetermined period from the end to the start of the operation. Causing the second original drive signal generation unit to generate the first original drive signal and the second original drive signal, respectively, and disconnecting the first original drive signal and the second original drive signal in the predetermined period. Instead, in the method for generating a drive signal, comprising the step of generating the drive signal, the first original drive signal and the second original drive signal are different from each other in the predetermined period. Both can be changed so that the voltage increases or decreases, the unit signal is generated based on the voltage in the predetermined period, and the element is a numerical value that is periodically input. The numerical information is set so as to operate based on the unit signal based on the voltage output corresponding to the information, and so that the voltages of the first original drive signal and the second original drive signal are equal in the predetermined period. The characteristic is a voltage output in response to the numerical information input to the first original drive signal generation unit and the second original drive signal generation unit, and the first original drive signal and the second original drive signal generation unit Prime mover The signal, so that the voltage in the predetermined period is a respective predetermined voltage is a method of generating a drive signal and sets the numerical information.
According to such a drive signal generation method, since almost all the effects described above are exhibited, the object of the present invention is most effectively achieved.

  Also, a first original drive for generating a first original drive signal having an element for executing an operation of ejecting ink based on the drive signal and a unit signal for defining from the start of the operation of the element to the end of the operation. A printing apparatus comprising: a signal generation unit; and a second original drive signal generation unit that generates a second original drive signal having a unit signal for defining from the start of operation of the element to the end of operation. Based on the measured characteristics of the drive signal generation unit and the second original drive signal generation unit, the first original drive signal and the second original drive signal in a predetermined period from the end of the operation to the start of the operation, The first original drive signal generation unit and the second original drive signal generation unit respectively generate the first original drive signal and the second original drive signal so that the voltages of the first original drive signal generation unit and the second original drive signal generation unit are equal to each other. 1 original drive signal and By switching between the serial second original drive signal, a computer program for realizing the function of generating the drive signals it is also feasible.

  In addition, (a) an element for executing an operation of ejecting ink based on the drive signal, and (b) a first original drive signal having a unit signal for defining from the operation start to the operation end of the element. A first original drive signal generation unit for generating; and (c) a second original drive signal generation unit for generating a second original drive signal having a unit signal for defining from the start of operation of the element to the end of operation; d) The first original drive signal generation unit and the second original drive so that the voltages of the first original drive signal and the second original drive signal are aligned in a predetermined period from the end of the operation to the start of the operation. Based on the result of actual measurement of the characteristics of the signal generation unit, the first original drive signal generation unit and the second original drive signal generation unit respectively generate the first original drive signal and the second original drive signal, The first master drive in the predetermined period By switching the signal and the second original drive signal, and a controller for generating the drive signal, the printing apparatus is feasible, characterized in that it comprises a (e).

  (A) a computer; (B) a printer connected to the computer and having the following (a) to (d); and (a) an operation for ejecting ink based on a drive signal. An element; and (b) a first original drive signal generation unit that generates a first original drive signal having a unit signal for defining from the start of operation of the element to the end of operation; and (c) from the start of operation of the element. A second original drive signal generator for generating a second original drive signal having a unit signal for defining the end of the operation; and (d) the first original drive in a predetermined period from the end of the operation to the start of the operation. The first original drive signal generation based on the result of actual measurement of the characteristics of the first original drive signal generation unit and the second original drive signal generation unit so that the voltages of the signal and the second original drive signal are uniform. And the second original drive signal generation unit , A controller for generating the first original drive signal and the second original drive signal, respectively, and generating the drive signal by switching between the first original drive signal and the second original drive signal in the predetermined period. And a printing system characterized by having (C).

=== Configuration of Printing System ===
<About the overall configuration>
First, the printing apparatus will be described together with a printing system. The printing system is a system including at least a printing apparatus and a printing control apparatus that controls the operation of the printing apparatus.

  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. In addition, regarding the medium, in the following description, a sheet S (see FIG. 3A), 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 display device 120 is for displaying a user interface of a computer program, for example. 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 ===
<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 is interposed between the printer 1 and exchanges data. 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 based on the computer program stored in the memory 114.

  The printer driver causes the computer 110 to realize a function of converting image data output from the application program into print data. The printer 1 receives the print data from the computer 110 and executes a printing operation. In other words, it can be said that the computer 110 controls the operation of the printer 1 via the print data. Therefore, the computer 110 functions as a print control apparatus by using this printer driver. The printer driver has a code for realizing a function of converting image data into print data.

  The print data is data in a format that can be interpreted by the printer 1 and includes various command data and pixel data. 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 pixel data is data related to pixels of an image to be printed. Here, the pixel is an area partitioned by a grid of grids virtually defined on the paper. In this pixel, a dot can be formed based on the pixel data.

  Then, the pixel data in the print data is converted into data relating to dots (for example, dot size data) formed in predetermined pixels on the paper. In the present embodiment, the pixel data is composed of 2-bit data. That is, the pixel data corresponds to pixel data “00” corresponding to no dot, pixel data “01” corresponding to small dots, pixel data “10” corresponding to formation of medium dots, and large dots. Pixel data “11”. Therefore, the printer 1 can form dots with four gradations.

  The printer driver performs resolution conversion processing, color conversion processing, halftone processing, rasterization processing, and the like in order to convert image data output from the application program into print data. The printer driver is provided in a state where it is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM. The printer driver can also be downloaded to the computer 110 via the Internet.

=== Printer ===
<About the configuration of the printer 1>
Next, the configuration of the printer 1 will be described. Here, FIG. 3A is a diagram illustrating a configuration of the printer 1 of the present embodiment. FIG. 3B is a vertical cross-sectional view for explaining the overall configuration of the printer 1 of the present embodiment. In the following description, reference is also made to the block diagram of FIG.

  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 control unit 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.

  The paper transport mechanism 20 corresponds to a medium transport unit that transports a medium. The paper transport mechanism 20 feeds the paper S 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. 3A and 3B, the paper transport mechanism 20 includes a paper feed roller 21, a transport motor 22, a transport roller 23, a platen 24, and a paper discharge roller 25. The paper feed roller 21 is a roller for automatically feeding the paper S inserted into the paper insertion opening into the printer 1 and has a D-shaped cross section in this example. The transport motor 22 is a motor for transporting the paper S in the transport direction, and its operation is controlled by the printer-side controller 60. The transport roller 23 is a roller for transporting the paper S sent by the paper feed roller 21 to a printable area. The operation of the transport roller 23 is also controlled by the transport motor 22. The platen 24 is a member that supports the paper S being printed from the back side of the paper S. The paper discharge roller 25 is a roller for carrying the paper S that has been printed.

  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. Since the head unit 40 includes the head 41, the carriage movement direction corresponds to the movement direction of the head 41, and the carriage movement mechanism 30 corresponds to a head movement unit that moves the head 41 in the movement direction. The carriage moving mechanism 30 includes a carriage motor 31, a guide shaft 32, a timing belt 33, a driving pulley 34, and a driven 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. A driven 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 driving pulley 34 and a driven 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.

  The head unit 40 is for ejecting ink toward the paper S. Here, FIG. 4 is an exploded perspective view of the head unit 40. FIG. 5A is a cross-sectional view illustrating the structure of the head 41. FIG. 5B is a diagram illustrating the arrangement of the nozzles Nz.

  The head unit 40 has a structure shown in FIG. 4, for example. That is, the head unit 40 includes a head 41, a needle side case member 42, and a head side case member 43. The needle-side case member 42 is a member having an ink supply needle 421 that is inserted into the ink cartridge IC (see FIG. 3A), and is created by molding resin, for example. The head side case member 43 is a member to which the head 41 is attached, and is created by molding resin, for example. The head side case member 43 is provided with a substrate placement portion 431. The substrate placement portion 431 is a portion where the head control board 44 is placed, and is formed by a substantially rectangular recess. The head control board 44 and the head 41 are electrically connected by a film-like head side wiring member 45. That is, the head side wiring member 45 is electrically connected at one end to the piezo element 417 (PZT, see FIG. 5A) of the head 41 and electrically connected to the head control board 44 at the other end. It is connected. The head control board 44 is provided with a head controller HC (sub controller) for controlling the head 41 and a connector 441. The head controller HC will be described later. The head control board 44 and the printer-side controller 60 are electrically connected by a film-like controller-side wiring board FC (see FIG. 3A).

  The head 41 included in the head unit 40 has, for example, the structure shown in FIG. 5A. The illustrated head 41 includes a flow path unit 41A and an actuator unit 41B. The flow path unit 41A includes a nozzle plate 411 provided with a nozzle Nz, a storage chamber forming substrate 412 in which an opening serving as an ink storage chamber 412a is formed, and a supply port forming substrate 413 in which an ink supply port 413a is formed. have. The nozzle plate 411 is bonded to one surface of the storage chamber forming substrate 412, and the supply port forming substrate 413 is bonded to the other surface. The actuator unit 41B has a pressure chamber forming substrate 414 in which an opening to be a pressure chamber 414a is formed, a vibration plate 415 that partitions a part of the pressure chamber 414a, and an opening to be a supply side communication port 416a. A lid member 416 and a piezo element 417 formed on the surface of the vibration plate 415 are provided. The head 41 is formed with a series of flow paths from the ink storage chamber 412a to the nozzle Nz through the pressure chamber 414a. In use, this flow path is filled with ink, and by deforming the piezo element 417, ink can be ejected from the corresponding nozzle Nz. Therefore, in the head 41, the piezo element 417 corresponds to an element for executing an operation of ejecting ink.

  As shown in FIG. 5B, the nozzles Nz are grouped for each type of ink to be ejected, and a nozzle row is configured by each group. The exemplified head 41 has four nozzle rows including a black ink nozzle row Nk, a cyan ink nozzle row Nc, a magenta ink nozzle row Nm, and a yellow ink nozzle row Ny, and can eject four colors of ink. It is. Each nozzle row has n (in this embodiment, n = 180) nozzles Nz. In these nozzle rows, the nozzles Nz are arranged at a constant interval (nozzle pitch: k · D) along a predetermined arrangement direction (in this example, the conveyance direction). Here, D is a minimum dot pitch in the transport direction, that is, an interval at the highest resolution of dots formed on the paper S. K is a coefficient representing the relationship between the minimum dot pitch D and the nozzle pitch, and is set to an integer of 1 or more.

  In the printer 1, as described above, there is no dot corresponding to the pixel data “00”, formation of a small dot corresponding to the pixel data “01”, formation of a medium dot corresponding to the pixel data “10”, and Four types of control of forming large dots corresponding to the pixel data “11” can be performed. For this reason, a plurality of types of ink having different amounts can be ejected from each nozzle Nz. For example, from each nozzle Nz, there are three types of ink consisting of large ink droplets capable of forming large dots, medium ink droplets capable of forming medium dots, and small ink droplets capable of forming small dots. Can be discharged. The relationship between pixel data and ejected ink will be described later.

  The detector group 50 is for monitoring the status of the printer 1. The detector group 50 includes a linear encoder 51, a rotary encoder 52, a paper detector 53, a paper width detector 54, and the like. The linear encoder 51 is for detecting the position of the carriage CR (head 41, nozzle Nz) in the carriage movement direction. The rotary encoder 52 is for detecting the rotation amount of the transport roller 23. The paper detector 53 is for detecting the leading end position of the paper S to be printed. The paper width detector 54 is a sensor for detecting the width of the paper S to be printed.

  The printer-side controller 60 controls the printer 1. The printer-side controller 60 corresponds to a controller that applies the drive signal COM to the piezo element 417. The drive signal COM will be described later. 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 that 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. The CPU 62 controls the head control signals (clock signal CLK, pixel data SI, latch signal LAT, first change signal CH_A, second change signal CH_B, see FIG. 14) for controlling the operation of the head 41. Output to part HC. Further, the CPU 62 outputs a control signal for generating the drive signal COM to the drive signal generation circuit 70.

  The drive signal generation circuit 70 generates a drive signal COM that is commonly used in each nozzle row. The drive signal COM of this embodiment is used in common for all the piezo elements 417 corresponding to one nozzle row. Here, FIG. 6 is a block diagram illustrating the configuration of the drive signal generation circuit 70.

  The drive signal generation circuit 70 can simultaneously generate a plurality of types of drive signals COM. The drive signal generation circuit 70 of the present embodiment includes a first original drive signal generator 70A that generates a first original drive signal COM_A and a second original drive signal generator 70B that generates a second original drive signal COM_B. is doing. The first original drive signal generation unit 70A includes a first waveform generation circuit 71A and a first current amplification circuit 72A, and the second original drive signal generation unit 70B includes the second waveform generation circuit 71B and the second current. And an amplifier circuit 72B. 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 waveform generation circuit 71A and the first current amplification circuit 72A.

  FIG. 7 is a block diagram for explaining the configuration of the first waveform generation circuit 71A and the second waveform generation circuit 71B. The configuration of the second waveform generation circuit 71B is indicated by parenthesized symbols. The first waveform generation circuit 71A includes a digital-analog converter (D / A converter) 715A and a voltage amplification circuit 716A.

  The digital-analog converter 715A converts DAC value data as numerical information periodically input under the control of the CPU 62 into an analog signal. The voltage amplification circuit 716A is electrically connected to the output terminal of the digital-analog converter 715A. The voltage amplification circuit 716A amplifies the voltage of the analog signal output from the digital-analog converter 715A to a voltage at which the piezo element 417 can operate. That is, the first waveform generation circuit 71A and the second waveform generation circuit 71B of the present embodiment convert the analog signal corresponding to the input DAC value every time the clock signal CLK having a predetermined period is input, The voltage and current of the analog signal thus generated are amplified to generate the original drive signal. For this reason, data of a plurality of types of DAC values is set in the memory 63 so that the output voltage changes by a predetermined amount each time the DAC value increases, and is stored in association with an address.

  FIG. 8 is a diagram for explaining the concept of the DAC value stored in the memory 63. As shown in the figure, here, the DAC value “0h (hexadecimal notation)” is stored at the address “0000” so that the output voltage becomes the minimum value of 1.4 V, and the output is output at the address “1023”. A DAC value “3FFh (hexadecimal notation)” that stores the maximum voltage of 42.32 V is stored. Hereinafter, the DAC value is expressed in hexadecimal with “h” added to the end. In each address between the addresses “0000” to “1023”, DAC values whose output voltages are different by a predetermined amount (here, 0.04 V) are sequentially stored. The output voltage shown in FIG. 8 is an output voltage when the DAC value is input to the ideal first original drive signal generation unit 70A and the second original drive signal generation unit 70B in terms of design. A voltage is not always obtained.

  FIG. 9 is a diagram for explaining an example of an ideal unit signal generated for ejecting ink in the original drive signal, and FIG. 10 is information for generating the unit signal shown in FIG. 4 is a diagram for explaining the concept of information stored in a memory 63. FIG.

  As shown in FIG. 10, in the memory 63, as information for generating a unit signal, between the points A and B, between the points C and D, between the points E and F in the waveform showing the unit signal shown in FIG. Voltage value between point H, point A and point B, point B and point C, point C and point D, point D and point E, point E and point F, point F and point G Each time, maximum amplitude Vh, and minimum voltage VL are stored. At this time, the voltage values between the points AB, the points CD, the points EF, and the points GH are represented by functions based on the maximum amplitude Vh. For example, the voltage between points AB and GH is “Vh × 0.4 + VL”, the voltage between points CD is “Vh × 0 + VL”, and the voltage between points EF is “Vh × 1 + VL”. It is shown. The time between each time point is indicated by the number of clocks counted between each time point. That is, when “36 V” is stored as the maximum amplitude Vh and “1.4 V” is stored as the minimum voltage VL, the voltage is held at “15.8 V” for 4 clocks between points A and B. Between points C, the voltage is changed from “15.8V” to “1.4V” in 4 clocks. Between points CD, the voltage is held at “1.4V” for 2 clocks, and between points DE. The voltage is changed from “1.4 V” to “37.4 V” in 3 clocks, the voltage is held at “37.4 V” for 3 clocks between the points EF, and the voltage is “37” between the points FG. .4V "is changed to" 15.8V "in 6 clocks, and after time G, it is held at" 15.8V "until the CH signal is input. That is, time H indicates the time when the CH_A (CH_B) signal is input.

  Based on the information (FIG. 10) for generating the unit signal as shown in FIG. 9, the CPU 62 of the printer-side controller 60 outputs the DAC value input to the digital / analog converter 715A (715B) in synchronization with the clock signal. Generate the data table shown. That is, this DAC value corresponds to “numerical information input periodically”. FIG. 11 is a diagram illustrating an example of a data table in which DAC values input in synchronization with the clock signal CLK and addresses are generated in order to generate unit signals, and FIG. 12 illustrates the first waveform generation circuit 71A. It is a figure for demonstrating operation | movement of.

  That is, in a predetermined area of the memory 63, DAC values sequentially output according to the clock signal are stored in association with the addresses. For example, between the points A and B of the original drive signal shown in FIG. 12, the DAC associated with the output voltage “15.8 V” is triggered by a latch signal LAT, which will be described later, until the fourth clock including the latch signal LAT. The value “168h” is output in synchronization with the clock signal CLK. Therefore, “168h” is stored in the addresses 0 to 3. The voltage is changed stepwise so that the output voltage becomes “1.4 V” in the next 4 clocks from the 5th clock to the 8th clock. That is, the DAC value “010Eh” associated with the output voltage “12.2 V” is output at the fifth clock from the latch signal LAT, and the DAC associated with the output voltage “8.6 V” is output at the sixth clock. The value “0B4h” is output, the DAC value “05Ah” associated with the output voltage “5V” is output at the seventh clock, and the eighth clock is associated with the output voltage “1.4V”. The DAC value is set such that the DAC value “000h” is output. In this way, each time the clock signal CLK is input, the DAC value to be output is associated with the address and sequentially stored in the memory 63 to form a data table.

  The CPU 62 of the printer-side controller 60 first moves the pointer indicating the address of the memory 63 to the address 0 of the data table based on the latch signal LAT, and converts the DAC value stored at the address 0 to the digital-analog converter 715A. To output. Thereafter, each time the clock signal CLK is input, the signal is sequentially moved to the address indicated by the pointer, and the DAC value stored at the address indicated by the pointer is output to the digital / analog converter 715A of the first waveform generation circuit 71A. To do. A signal generated by operating the first waveform generation circuit 71A based on the set DAC value is amplified by the voltage amplification circuit 716A and the first current amplification circuit 72A to generate a first original drive signal waveform. The

  Next, the head controller HC will be described. Here, FIG. 13 is a block diagram illustrating the configuration of the head controller HC. As shown in FIG. 13, the head controller HC includes a first shift register 81A, a second shift register 81B, a first latch circuit 82A, a second latch circuit 82B, a decoder 83, a control logic 84, A prevention circuit 85, a first level shifter 86A, a second level shifter 86B, a first switch 87A, and a second switch 87B are provided. Except for the control logic 84, that is, the first shift register 81A, the second shift register 81B, the first latch circuit 82A, the second latch circuit 82B, the decoder 83, the prevention circuit 85, and the first level shifter. The 86A, the second level shifter 86B, the first switch 87A, and the second switch 87B are provided for each piezo element 417. Since the piezo element 417 is provided for each nozzle Nz from which ink is ejected, these parts are also provided for each nozzle Nz.

  The head controller HC performs control for ejecting ink based on print data (pixel data SI) from the printer-side controller 60. In the present embodiment, the pixel data is composed of 2 bits, and this pixel data is sent to the recording head 41 in synchronization with the clock signal CLK. This pixel data is sent in order from the upper bit group to the lower bit group. For example, the upper bit of the nozzle Nz (# 1), the upper bit of the nozzle Nz (# 2), ..., the upper bit of the nozzle Nz (# 179), the upper bit of the nozzle Nz (# 180), the nozzle Nz (# 1) , Lower bits of nozzle Nz (# 2),..., Lower bits of nozzle Nz (# 179), and lower bits of nozzle Nz (# 180). For this reason, first, the upper bit group of the pixel data is set in the second shift register 81B. When the upper bit group of the pixel data is set in the second shift register 81B for all the nozzles Nz, the lower bit group of the pixel data is subsequently set in the second shift register 81B. With the setting of the lower bit group of the pixel data, the upper bit group of the pixel data is shifted and set in the first shift register 81A.

  A first latch circuit 82A is electrically connected to the first shift register 81A, and a second latch circuit 82B is electrically connected to the second shift register 81B. When the latch signal LAT from the printer-side controller 60 becomes H level, that is, when the latch pulse is input to the first latch circuit 82A and the second latch circuit 82B, the first latch circuit 82A is the upper bit of the pixel data. The second latch circuit 82B latches the lower bits of the pixel data. Pixel data (a set of upper bits and lower bits) latched by the first latch circuit 82A and the second latch circuit 82B is input to the decoder 83, respectively. The latch signal LAT described here is also a latch signal LAT used as a trigger when generating the original drive.

  The decoder 83 performs decoding based on the upper bits and lower bits of the pixel data, constitutes the first drive signal COM_A and the second drive signal COM_B, and includes waveform units SS11 to SS16, SS21 to SS26 including unit signals (FIG. 14). The selection data for selecting “will be described later” is generated. Here, the waveform sections SS11 to SS26 show the entire waveforms generated in the respective times T1 to T6, and the unit signal changes in voltage to cause the piezo element 417 to perform the operation of ejecting ink. 9 shows a signal between point B and point G shown in FIG. 9, which defines the part to be operated, that is, from the start to the end of the operation of the piezo element 417.

  The selection data in this embodiment is generated separately for the first original drive signal COM_A and the second original drive signal COM_B. That is, the first selection data corresponding to the first original drive signal COM_A is configured by 6-bit data corresponding to each of the first waveform portion SS11 to the sixth waveform portion SS16. Similarly, the second selection data corresponding to the second original drive signal COM_B is also configured by 6-bit data corresponding to each of the first waveform portion SS21 to the sixth waveform portion SS26. The decoder 83 that performs such an operation corresponds to a selection data generation unit, and generates 6-bit selection data from 2-bit pixel data (gradation data) by the number of original drive signals COM_N.

  The decoder 83 also receives a timing signal from the control logic 84. The control logic 84 functions as a timing signal generator together with the printer-side controller 60, and generates a timing signal based on the latch signal LAT and the change signals CH_A and CH_B. This timing signal is also generated for each original drive signal COM_N. That is, the first timing signal TIM_A for the first original drive signal COM_A and the second timing signal TIM_B for the second original drive signal COM_B are generated. As shown in FIG. 14, in the first timing signal TIM_A, the timing pulse is generated in synchronization with the generation timing of the latch pulse and the change pulse for the first original drive signal COM_A. The second timing signal TIM_B is generated in synchronization with the latch pulse and the change pulse for the second original drive signal COM_B.

  The 6-bit selection data generated by the decoder 83 is sequentially output from the upper bit side at the timing defined by the timing pulse. The output selection data passes through the prevention circuit 85 and is then input to the first level shifter 86A and the second level shifter 86B. That is, the first selection data is input to the first level shifter 86A in synchronization with the rising timing of the timing pulse included in the first timing signal TIM_A. Further, the second selection data is input to the second level shifter 86B in synchronization with the rising timing of the timing pulse included in the second timing signal TIM_B.

  The first level shifter 86A and the second level shifter 86B function as voltage amplifiers. That is, when the selection data is [1], the first level shifter 86A and the second level shifter 86B are turned on so that the corresponding switches (the first switch 87A and the second switch 87B) are boosted to a voltage enough to drive. Output a signal. For example, when the first selection data is [1], an ON signal boosted to several tens of volts is output to the first switch 87A. Similarly, when the second selection data is [1], an ON signal boosted to several tens of volts is output to the second switch 87B.

  In the present embodiment, a prevention circuit 85 is disposed between the decoder 83 and the first level shifter 86A and the second level shifter 86B. The prevention circuit 85 is for preventing the first original drive signal COM_A and the second original drive signal COM_B from being simultaneously applied to one piezo element 417. The prevention circuit 85 is configured by a logic circuit, for example.

  The first original drive signal COM_A from the drive signal generation circuit 70 is applied to the input side of the first switch 87A, and the second original drive signal COM_B is applied to the input side of the second switch 87B. . A piezo element 417 is electrically connected to the common output side of the first switch 87A and the second switch 87B. The first switch 87A and the second switch 87B are provided for each original drive signal COM_N to be generated. Then, the waveform portions SS11 to SS16 constituting the first drive signal COM_A and the waveform portions SS21 to SS26 constituting the second drive signal COM_B are selectively applied to the piezo element 417.

  The selection data controls the operation of the first switch 87A and the second switch 87B. That is, during a period in which the selection data input to the first switch 87A is [1], the first switch 87A is in a connected state, and the first drive signal COM_A is applied to the piezo element 417. Similarly, the second drive signal COM_B is applied to the piezo element 417 during the period in which the selection data input to the second switch 87B is [1]. The voltage of the piezo element 417 is determined according to the applied first drive signal COM_A or second drive signal COM_B. On the other hand, during the period when the selection data input to the first switch 87A and the selection data input to the second switch 87B are both [0], the first switch 87A and the second switch 87B The electrical signal for operating the two switch 87B is not output. That is, an ON signal is output from either one of the first switch 87A and the second switch 87B, or no ON signal is output from either of them, whereby the first original drive signal COM_A and the first switch The two original drive signals COM_B are switched at timings other than those unit signals to generate one drive signal COM. At this time, the piezo element 417 behaves like a capacitor and maintains the voltage just before the stop when the application of the drive signal COM is stopped. Accordingly, during the period in which the application of the drive signal COM is stopped, the piezo element 417 maintains the deformed state immediately before the application of the drive signal COM is stopped. The contents of the selection data will be described in detail later.

=== Specific Control at the Time of Dot Formation ===
<About the drive signal COM>
FIG. 14 is a diagram illustrating the first original drive signal COM_A, the second original drive signal COM_B, and necessary control signals.

  The illustrated first original drive signal COM_A includes a first waveform section SS11 generated in the period T1, a second waveform section SS12 generated in the period T2, a third waveform section SS13 generated in the period T3, and a period. It has a fourth waveform section SS14 generated in T4, a fifth waveform section SS15 generated in period T5, and a sixth waveform section SS16 generated in period T6. Among these waveform portions, the first waveform portion SS11, the third waveform portion SS13, and the fifth waveform portion SS15 have a drive pulse PS. This drive pulse PS has the same waveform as the drive pulse PS shown in FIG. 9, and corresponds to a unit signal. The second waveform section SS12, the fourth waveform section SS14, and the sixth waveform section SS16 are located between the maximum voltage and the minimum voltage of the drive pulse PS, and are constant at the reference voltage VC serving as a reference. Yes. This reference voltage VC corresponds to the start voltage and end voltage of the drive pulse PS. Therefore, in the example of the present embodiment, in the first original drive signal COM_A, the drive pulse PS is generated in the period T1, and a constant signal (constant voltage signal) is generated in the reference voltage VC in the period T2. In addition, the driving pulse PS is generated in the periods T3 and T5, and the constant voltage signal is generated in the periods T4 and T6. In short, the first original drive signal COM_A is a signal in which the drive pulse PS and the constant voltage signal are generated alternately.

  The illustrated second original drive signal COM_B includes a first waveform section SS21 generated in the period T1, a second waveform section SS22 generated in the period T2, a third waveform section SS23 generated in the period T3, and a period. It has a fourth waveform section SS24 generated in T4, a fifth waveform section SS25 generated in period T5, and a sixth waveform section SS26 generated in period T6. In the present embodiment, the first waveform portion SS21 to the sixth waveform portion SS26 of the second original drive signal COM_B have the same time width as the first waveform portion SS11 to the sixth waveform portion SS16 of the corresponding first original drive signal COM_A. It has been established. Accordingly, the first change signal CH_A for the first original drive signal COM_A and the second change signal CH_B for the second original drive signal COM_B are aligned at the H level. In other words, the pulses are generated synchronously.

  In the second original drive signal COM_B, the first waveform section SS21, the third waveform section SS23, and the fifth waveform section SS25 are constant voltage signals that are constant at the reference voltage VC. The second waveform section SS22, the fourth waveform section SS24, and the sixth waveform section SS26 have a drive pulse PS. The drive pulse PS has the same waveform as the drive pulse PS included in the first original drive signal COM_A, and corresponds to another unit signal. The second original drive signal COM_B can be said to be a signal in which the constant voltage signal and the drive pulse PS are generated alternately.

  In terms of the relationship with the first original drive signal COM_A, the second original drive signal COM_B is a period from the end of generation of the drive pulse PS to the start of generation of the next drive pulse PS in the first original drive signal COM_A (that is, It can be said that the drive pulse PS is generated during the constant voltage signal generation periods T2, T4, T6). Similarly, when the first original drive signal COM_A is expressed in relation to the second original drive signal COM_B, the first original drive signal COM_A is the next drive pulse from the end of the generation of the drive pulse PS in the second original drive signal COM_B. It can be said that the signal generates the drive pulse PS during the period until the start of generation of PS.

  In short, the first original drive signal COM_A and the second original drive signal COM_B can be said to be signals that generate the drive pulse PS in the non-generation period of the drive pulse PS in the other drive signal COM.

<About gradation control>
Next, gradation control in the printer 1 will be described. Here, FIG. 15A is a diagram illustrating a waveform portion applied to the piezo element 417 during the formation of small dots, the formation of medium dots, and the formation of large dots. FIG. 15B is a diagram for explaining pixel data (tone values), a waveform portion selection pattern, and selection data. In this multi-gradation control, the operations of the first switch 87A and the second switch 87B are controlled based on the selection data generated by the decoder 83.

  First, the case of no dot formation (pixel data [00]) will be described. In this case, as shown in FIG. 15B, the decoder 83 generates first selection data [000000] and second selection data [000000] based on pixel data [00] indicating non-recording. The first selection data [000000] and the second selection data [000000] are output to the first switch 87A and the second switch 87B in order from the higher bit side at the timing (rising timing) when the timing signal becomes H level. Is done. Here, the first selection data is [000000], and the second selection data is also [000000]. Therefore, no voltage is applied to the piezo element 417 by the waveform portions SS11 to SS16 of the first original drive signal COM_A. Similarly, no voltage is applied to the piezo element 417 by the waveform portions SS21 to SS26 of the second original drive signal COM_B. As a result, no voltage is applied to the piezo element 417, and no ink is ejected from the nozzle Nz.

  Next, the case of forming small dots (pixel data [01]) will be described. In this case, as shown in FIG. 15B, the decoder 83 generates first selection data [001000] and second selection data [000000] based on the pixel data [01] indicating the formation of small dots. As described above, the first selection data [001000] and the second selection data [000000] are sequentially sent from the higher bit side to the first switch 87A and the second switch 87B at the timing when the timing signal becomes H level. Is output. Here, the first selection data is [001000]. Therefore, the first original drive signal COM_A is applied to the piezo element 417 during the period T3 as shown in FIG. 15A. That is, a voltage is applied to the piezo element 417 by the third waveform section SS13. On the other hand, the second selection data is [000000]. Therefore, no voltage is applied to the piezo element 417 depending on the second original drive signal COM_B. As a result, a voltage is applied to the piezo element 417 only by the third waveform section SS13 generated in the period T3, and an amount of ink corresponding to a small dot is ejected from the nozzle Nz. As a result, small dots are formed on the paper S.

  Next, the case of formation of medium dots (pixel data [10]) will be described. In this case, as shown in FIG. 15B, the decoder 83 generates the first selection data [001000] and the second selection data [010100] based on the pixel data [10] indicating the formation of medium dots. When the first selection data [001000] is output to the first switch 87A, the first original drive signal COM_A is applied to the piezo element 417 in the period T3. That is, as shown in FIG. 15A, a voltage is applied to the piezo element 417 by the third waveform section SS13. When the second selection data [010100] is output to the second switch 87B, the second original drive signal COM_B is applied to the piezo element 417 in the period T2 and the period T4. That is, as shown in FIG. 15A, a voltage is applied to the piezo element 417 by the second waveform section SS22 and the fourth waveform section SS24. As a result, a voltage is applied to the piezo element 417 by the second waveform section SS22 generated in the period T2, the third waveform section SS13 generated in the period T3, and the fourth waveform section SS24 generated in the period T4. The amount of ink corresponding to the medium dot is ejected from the nozzle Nz. As a result, medium dots are formed on the paper S. At this time, as a result, the first original drive signal COM_A and the second original drive signal COM_B are switched between the period T2 and the period T3 and between the period T3 and the period T4.

  Next, the case of large dot formation (pixel data [11]) will be described. In this case, as shown in FIG. 15B, the decoder 83 generates first selection data [101010] and second selection data [010101] based on the pixel data [11] indicating the formation of large dots. When the first selection data [101010] is output to the first switch 87A, as shown in FIG. 15A, the first original drive signal COM_A is applied to the piezo element 417 in the periods T1, T3, and T5. The When the second selection data [010101] is output to the second switch 87B, the second original drive signal COM_B is applied to the piezo element 417 in the period T2, the period T4, and the period T6 as shown in FIG. 15A. The Accordingly, a voltage is applied to the piezo element 417 by the three waveform portions SS11, SS13, and SS15 included in the first original drive signal COM_A and the three waveform portions SS22, SS24, and SS26 included in the second original drive signal COM_B. An amount of ink corresponding to a large dot is ejected from Nz. As a result, large dots are formed on the paper S. At this time, as a result, between the period T1 and the period T2, between the period T2 and the period T3, between the period T3 and the period T4, between the period T4 and the period T5, and between the period T5 and the period T6. Thus, the first original drive signal COM_A and the second original drive signal COM_B are switched.

  As described above, in the present embodiment, the waveform portion that generates the voltage applied to the piezo element 417 is dispersed into the first original drive signal COM_A and the second original drive signal COM_B. That is, the first original drive signal COM_A and the second original drive signal COM_B are different original drive signals having different timings for generating the drive pulse PS. Thus, by generating and using the drive signal COM by switching the original drive signals having different generation timings of the drive pulses PS, the generation intervals of the drive pulses PS included in each of the first original drive signal COM_A and the second original drive signal COM_B can be set. For example, the drive signal can be generated by generating the drive pulse PS included in the second original drive signal COM_B between the drive pulses PS included in the first original drive signal COM_A. Therefore, as each original drive signal, it is possible to eject ink from the piezo element 417 at a high frequency while ensuring a sufficient drive pulse generation interval. In the example of the present embodiment, regarding the first original drive signal COM_A and the second original drive signal COM_B, the number of drive pulses PS that each has in the repetition period T is 3, but each of the repetitions as the drive signal COM It is possible to set the number of drive pulses PS in the period T to six. That is, the number of drive pulses PS included in each of the first original drive signal COM_A and the second original drive signal COM_B is three, and a certain drive pulse PS is generated in the first original drive signal COM_A and the second original drive signal COM_B. By providing a period from the end to the start of generation of the next drive pulse PS, it is possible to suppress the heat generation of the drive signal generation circuit for generating each original drive signal and print a finer image at high speed. Is possible.

=== Outline of the Embodiment ===
The description so far has been made on the assumption that the ideal first original drive signal generation unit 70A and the second original drive signal generation unit 70B are used. That is, the description is based on the assumption that when a predetermined DAC value is input, a voltage according to the set design value is applied to the piezo element 417. However, in practice, the characteristics of the original drive signal generator may vary individually. Specifically, in different original drive signal generation units, even if the same DAC value is input to each original drive signal generation unit, the same output voltage is not always obtained. In the printer 1 of this embodiment, the drive signal applied to the piezo element 417 may be generated by switching between the two original drive signals COM_A and COM_B. That is, the two original drive signals COM_A and COM_B for generating the drive signal COM are respectively generated by different original drive signal generation units 70A and 70B. Therefore, when the characteristics of the first original drive signal generator 70A that generates the two original drive signals COM_A and COM_B are different from those of the second original drive signal generator 70B, the original drive signals COM_A and COM_B are switched. The theoretical voltage (reference voltage) may differ even though the voltage is theoretically the same. If the voltage when the first original drive signal COM_A and the second original drive signal COM_B are switched is different, the voltage changes abruptly at the moment of switching. When the voltage changes abruptly in this way, the ink may be ejected from the piezo element 417 just by switching the original drive signal, and the image quality may deteriorate. For this reason, in this embodiment, the DAC value is set so that the voltages of the original drive signals output from the two original drive signal generators 70A and 70B are aligned so that the voltage does not change suddenly when switching.

=== DAC Value Setting Example ===
The DAC value is set by first measuring the characteristics of the first original drive signal generation unit 70A and the second original drive signal generation unit 70B, for example, when the original drive signal generation units 70A and 70B are mounted in the printer 1 in advance. Keep it. Specifically, the DAC values “000h” to “3FFh” are sequentially input to the original drive signal generators 70A and 70B, and the output voltage is measured. Then, an actual measurement data table in which the output voltage actually measured for each original drive signal generation unit is associated with the DAC value is generated and stored in the memory 63.

  FIG. 16 is a diagram for explaining the concept of the actual measurement data table. In FIG. 16, only information necessary for explanation due to space limitations is shown, but the actual measurement data table has data for DAC values with input DAC values of “000h” to “3FFh”.

  FIG. 17 compares the original drive signals generated when the theoretical DAC values are input to the first original drive signal generation unit and the second original drive signal generation unit that generated the actual measurement data table shown in FIG. It is a figure for demonstrating. In FIG. 17, in order to compare the first original drive signal COM_A and the second original drive signal COM_B generated when the theoretical DAC value is input, the two original drive signals and the theoretical original drive signal are overlapped. Although shown, these signals do not actually overlap. The drive signal COM may be generated by switching the first original drive signal COM_A and the second original drive signal COM_B, but the switching timing is a reference voltage at which the unit signal in each of the original drive signals COM_A and COM_B is not output Is the output timing. That is, the timing for switching the two original drive signals COM_A and COM_B is the timing at which the CH signal is input in a predetermined period from the end of the operation of the piezo element 417 to the start of the operation. Between H. When the first original drive signal generation unit 70A and the second original drive signal generation unit 70B of the present embodiment are used, the voltage at this timing is 15.2V in the first original drive signal COM_A, The drive signal COM_B is 14.6V. For this reason, when the first original drive signal COM_A and the second original drive signal COM_B are switched at the timing of the reference voltage, the voltage changes at the moment of switching.

  Therefore, in the present embodiment, for example, the reference voltage of the first original drive signal COM_A output from the first original drive signal generation unit 70A and the second original drive signal COM_B output from the second original drive signal generation unit 70B. The DAC value is set based on the actual measurement data table so that the reference voltage is the theoretical reference voltage of 15.8V. That is, “177h” is set as the DAC value input to the first original drive signal generation unit 70A and “1C2h” is set as the DAC value input to the second original drive signal generation unit 70B so as to be the reference voltage.

  Next, as a data table for generating a unit signal, the DAC value to be input to the first original drive signal generation unit 70A and the second original drive signal generation unit 70B is converted into a theoretical DAC value and each original drive. Based on the actual measurement data table of the signal generators 70 </ b> A and 70 </ b> B, it is generated and stored in the memory 63. Specifically, the theoretical DAC value “168h” for setting the reference voltage to 15.8 V is different from, for example, the DAC value “177h” to be input to the first original drive signal generation unit 70A because it differs by 15 levels. A new data table in which each DAC value in the theoretical data table for generating the unit signal is changed to a value larger by 15 levels is generated and stored in the memory 63 as a data table for the first original drive signal generation unit 70A. To do. Similarly, the theoretical DAC value “168h” for setting the reference voltage of 15.8 V and the DAC value “1C2h” to be input to the second original drive signal generation unit 70B are different by 30 levels. A new data table in which each DAC value in the theoretical data table for generation is changed to a value larger by 30 levels is generated and stored in the memory 63 as a data table for the second original drive signal generation unit 70B.

  FIG. 18 is a diagram for explaining the concept of a new data table input to the first original drive signal generation unit 70A and the second original drive signal generation unit 70B. As shown in the figure, each of the new data tables stored as data tables for generating unit signals in the first original drive signal generation unit 70A and the second original drive signal generation unit 70B is a theoretical reference voltage. The DAC value is changed to obtain Therefore, when the CPU 62 of the printer-side controller 60 sequentially moves the pointer indicating the address of the memory 63 and outputs the DAC value to the digital-analog converter 715A, the first original drive signal generator 70A and the second original drive signal are output. From the generation unit 70B, an original drive signal with a reference voltage of 15.8V is output. For this reason, in the first original drive signal COM_A and the second original drive signal COM_B, the first original drive signal COM_A and the second original drive are generated during the period from the end of the generation of a certain drive pulse PS to the start of the generation of the next drive pulse PS. Even if the signal COM_B is switched, the voltage does not change abruptly at the moment of switching. Accordingly, since the voltage does not change even when the first original drive signal COM_A and the second original drive signal COM_B are switched, it is possible to prevent ink from being ejected from the piezo element 417 simply by switching the original drive signal. It is. Here, if the DAC value is set so that only the reference voltages of the original drive signals generated by the different original drive signal generation units are aligned, it is possible to suppress the voltage from changing suddenly at the moment of switching the original drive signal. It is done. However, in the present embodiment, not only the reference voltages are set to be uniform, but the voltage values of the entire unit signals are set to be uniform with reference to the reference voltage as the voltage for a predetermined period. For this reason, not only the reference voltage but also the total voltage in the first original drive signal COM_A and the second original drive signal COM_B, that is, between the points AB and BC, and the points CD shown in FIG. The DAC value is set so that the voltages are all the same between the D-E point, the EF point, the FG point, and the GH point. For this reason, not only the ejection of ink when switching between the first original drive signal COM_A and the second original drive signal COM_B is prevented, but also the ink ejected by the unit signal included in each original drive signal. It is possible to make the amount almost the same. That is, when setting the DAC value so that the whole voltages in the first original drive signal COM_A and the second original drive signal COM_B are made uniform, the voltage of the whole original drive signal is made uniform after setting the reference voltage. The DAC value is set. For this reason, the setting of the DAC value so that the entire voltages in the first original drive signal COM_A and the second original drive signal COM_B are equalized is one more setting step than the case where the reference voltages are simply equalized. is necessary. For this reason, the process of setting the DAC value becomes complicated, but it is possible to suppress variations in image quality and color tone of each printer by setting the DAC value so that the voltages of the entire original drive signal are made uniform.

  In the present embodiment, the DAC value is set so that the voltages are equalized so that an original drive signal having a reference voltage of 15.8 V is output from the first original drive signal generator 70A and the second original drive signal generator 70B. Although the example which sets this was demonstrated, it is not restricted to this. For example, based on the measured data tables of the first original drive signal generation unit 70A and the second original drive signal generation unit 70B, the output voltage of the other original drive signal generation unit is the output voltage of the other original drive signal generation unit. Only the DAC value input to the other original drive signal generation unit may be set so as to be aligned. In this case, it is easy to set the DAC value to be input to one of the original drive signal generation units. However, when a plurality of printers are considered, image quality, color tone, and the like may vary depending on each printer. Therefore, the above-described embodiment in which the DAC value input to any of the original drive signal generation units is set is superior.

=== About printing operation ===
In the printer 1 having the above-described configuration, the printer-side controller 60 controls the control target units (the paper transport mechanism 20, the carriage moving mechanism 30, the head unit 40, and the drive signal generation circuit 70) according to the computer program stored in the memory 63. Control. Therefore, this computer program has a code for executing this control. Then, the printing operation on the paper S is performed by controlling the control target portion.

  FIG. 19 is a flowchart for explaining printer processing. In order to set the DAC value so that the voltage does not change suddenly when the first original drive signal COM_A and the second original drive signal COM_B are switched, the printer 1 of the present embodiment generates the first original drive signal in advance. The actual measurement data table of the unit 70A and the second original drive signal generation unit 70B is generated. For this reason, separately from the printing operation of the printer 1, an actual measurement process for generating an actual measurement data table is executed in advance. This actual measurement processing may be executed by the CPU 62 sequentially inputting the DAC value from “000h” to the original drive signal generation unit, or may be performed by actual measurement using a device separate from the printer 1.

  The process executed for printing by the printer 1 includes an actual measurement process for generating an actual data table (S00), a reception process for a print command (S10), and a unit signal for generating a data table for generating a unit signal. Data generation processing (S20), paper feed processing (S30), dot formation processing (S40), transport processing (S50), paper discharge determination processing (S60), and paper discharge processing (S70) are included. Each process will be briefly described below.

  In the actual measurement process (S00), the DAC value is sequentially input from “000h” to the first original drive signal generation unit 70A, the output voltage is measured, and the first actual measurement data table in which the DAC value is associated with the output voltage is generated. The first actual measurement process (S01) to be performed, the DAC value is sequentially input from “000h” to the second original drive signal generation unit 70B, the output voltage is measured, and the second actual measurement data in which the DAC value and the output voltage are associated with each other. And a second actual measurement process (S02) for generating a table. The actual measurement data table generated by the first actual measurement process (S01) and the second actual measurement process (S02) is stored in the memory 63. That is, the first actual measurement process (S01) corresponds to “a step of actually measuring the characteristics of the first original drive signal generation unit 70A”, and the second actual measurement process (S02) is “the second original drive signal generation unit 70B. This corresponds to “a step of actually measuring characteristics”.

The print command reception process (S10) is a process of receiving a print command from the computer 110. In this operation, the printer-side controller 60 receives a print command via the interface unit 61.
In the unit signal data generation process (S20), the printer-side controller 60, after the operation of the piezo element 417 is completed, based on the first actual measurement data table and the second actual measurement data table stored in the actual measurement process (S00). The DAC value is set so that the voltages (reference voltages) VC of the first original drive signal COM-_A and the second original drive signal COM_B are equal in a predetermined period from the start to the operation start, and the first original drive signal COM-_A And the second original drive signal COM_B, each data table for generating a unit signal is generated. At this time, information (FIG. 10) indicating the original drive signal is selected based on the information indicating the print mode received in the print command reception process (S10), and first first original drive is selected based on the selected information. The DAC value of the reference voltage of the signal COM-_A and the second original drive signal COM_B is set (S21). Next, in order to generate the unit signal based on the DAC value of the set reference voltage, the DAC value to be input to the first original drive signal generation unit 70A and the second original drive signal generation unit 70B is generated for each clock signal. Each is set (S22), and a data table for generating a unit signal is set. Since the details of the unit signal data generation process (S20) have been described above, they are omitted here.

The paper feed process (S30) is a process of moving the paper S to be printed and positioning it at a print start position (so-called cue position). In this process, the printer-side controller 60 rotates the paper feed roller 21 and the transport roller 23 by driving the transport motor 22 and the like.
The dot formation process (S40) is a process for forming dots on the paper S. In this process, the printer-side controller 60 drives the carriage motor 31 and outputs a control signal to the drive signal generation unit and the head 41. At this time, the first original drive signal COM-_A and the second original drive signal COM_B are generated based on the respective data tables for generating the unit signal generated in the unit signal data generation process (S20). (S41). Then, the printer-side controller 60 selects the first original drive signal COM-_A and the second original drive signal COM_B for each clock signal based on the print data received from the computer 110, and generates the drive signal COM. (S42). Based on the generated drive signal COM, the printer-side controller 60 drives the piezo element 417 while the head 41 is moving, whereby ink is ejected from the nozzle Nz and dots are formed on the paper S.

  That is, based on the unit signal data generation process (S20) and each data table, the process of generating the first original drive signal COM-_A and the second original drive signal COM_B (S41) The first original drive signal generation unit and the second original drive signal generation unit respectively generate a first original drive signal and a second original drive signal ”, and the first original drive signal COM-_A and The process (S42) of generating the drive signal COM by selecting the second original drive signal COM_B for each clock signal as necessary, “switches between the first original drive signal and the second original drive signal in a predetermined period, This corresponds to “a step of generating a drive signal”.

The transport process (S50) is a process of moving the paper S in the transport direction. In this process, the printer-side controller 60 drives the carry motor 22 to rotate the carry roller 23. By this transport operation, dots can be formed at positions different from the dots formed by the previous dot formation operation.
The paper discharge determination process (S60) is a process for determining whether or not it is necessary to discharge the paper S to be printed. This determination is made by the printer-side controller 60 based on the presence or absence of print data, for example.
The paper discharge process (S70) is a process for discharging the paper S, and is performed under the condition that “discharge” is determined in the previous paper discharge determination. In this case, the printer-side controller 60 rotates the paper discharge roller 25 to discharge the printed paper S to the outside.

  In the present embodiment, information for generating a unit signal is stored in the memory 63, and an example of generating a data table for generating a unit signal based on this information when printing is described. A data table for generating unit signals may be stored in the memory 63 in advance. In this case, if the unit signals differ depending on the print mode, the data table stored in the memory 63 increases, so that information for generating the unit signal is stored in the memory 63 as in the above embodiment. It is desirable to memorize it.

  By the way, when the first original drive signal COM_A and the second original drive signal COM_B are switched, the reference between at least the first original drive signal COM_A and the second original drive signal COM_B is used so that the voltage does not change abruptly. The DAC value may be simply set so that the voltages are uniform. For this reason, as in the present embodiment, the reference voltage to be aligned is set to a voltage in a state where the voltage can be changed in the drive signal, either large or small, so that the first original drive signal and the second original drive signal are changed. Regardless of which of these is large or small, it is possible to generate the original drive signal so as to be easily aligned according to the actually measured value.

  In the present embodiment, as the characteristics of the first drive signal generation unit 70A and the second drive signal generation unit 70B, information that associates an input DAC value with an actually measured output voltage is stored, and this information is stored. In the above example, the DAC value is set so that the reference voltages of the first drive signal COM_A and the second drive signal COM_B are aligned. However, the method of setting the reference voltage to be aligned is not limited thereto. For example, a detection unit that detects the output voltages of the first drive signal generation unit 70A and the second drive signal generation unit 70B is provided, and each reference voltage is detected and detected as a characteristic of the first drive signal and the second drive signal. Based on the reference voltage, the first drive signal generation unit 70A and the second drive signal generation unit 70B may be controlled so that the reference voltages of the first drive signal and the second drive signal are aligned.

=== Other Embodiments ===
Each of the above embodiments has been described mainly with respect to the printing system 100 having the printer 1, which includes disclosure of a print control device, a print control method, and the like. The above-described embodiments are for facilitating understanding of the present invention, and are 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 above-described embodiment, the number of drive pulses PS included in the first drive signal COM_A and the number of drive pulses PS included in the second drive signal COM_B are the same. For example, in the first embodiment, the number of drive pulses PS in the repetition period T is three for the first drive signal COM_A and three for the second drive signal COM_B. However, the number of drive pulses PS may be different between the first drive signal COM_A and the second drive signal COM_B. For example, in a configuration in which a maximum of five drive pulses PS are applied to the piezo element 417 within one repetition period T, three drive pulses PS are included in the first drive signal COM_A, and 2 in the second drive signal COM_B. One drive pulse PS can be included.

  Further, the number of drive pulses PS may be changed for each repetition period T. For example, in a certain repetition period T, three drive pulses PS are included in the first drive signal COM_A, and two drive pulses PS are included in the second drive signal COM_B. In the next repetition period T, the first drive signal COM_A includes two drive pulses PS, and the second drive signal COM_B includes three drive pulses PS. Further, in the next repetition period T, the first drive signal COM_A includes three drive pulses PS, and the second drive signal COM_B includes two drive pulses PS. In this way, even if the number of drive pulses PS in the repetition period T is an odd number, the heat generation amounts of the first original drive signal generation unit 70A and the second original drive signal generation unit 70B can be equalized.

  In the above-described embodiment, two types of original drive signals are generated, but the present invention is not limited to this. For example, three or more types of original drive signals may be generated.

<About the printing system>
Regarding the printing system, in the above-described embodiment, the printing system 100 in which the printer 1 as a printing apparatus and the computer 110 as a printing control apparatus are separately configured has been described. However, the present invention is not limited to this configuration. The printing system may be one in which a printing apparatus and a print control apparatus are integrated.

<About drive elements>
In the above-described embodiment, ink is ejected using the piezo element 417. However, the element that ejects ink is not limited to the piezo element 417. For example, any element that can execute an operation for ejecting ink, such as a heating element or a magnetostrictive element, can be used.

<About ink>
Since the above-described embodiment is an embodiment of the printer 1, the dye ink or the pigment ink is ejected from the nozzle Nz. However, the ink ejected from the nozzle Nz is not limited to such ink. Also, the ink colors are not limited to the four colors described above.

<About other application examples>
In the above-described embodiment, the printer 1 has been described. 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 technique as that of the present embodiment may be applied to various recording apparatuses to which an inkjet technique such as an apparatus and a DNA chip manufacturing apparatus 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. FIG. 3A is a diagram illustrating a configuration of the printer according to the present embodiment. FIG. 3B is a cross-sectional view of the overall configuration of the printer of this embodiment. It is a disassembled perspective view of a head unit. FIG. 5A is a cross-sectional view illustrating the structure of the head. FIG. 5B is a diagram illustrating the arrangement of nozzles. It is a block diagram explaining the structure of a drive signal generation circuit. It is a block diagram for demonstrating the structure of a 1st waveform generation circuit and a 2nd waveform generation circuit. It is a figure for demonstrating the concept of the DAC value memorize | stored in memory. It is a figure for demonstrating an example of the ideal unit signal produced | generated in order to discharge an ink in an original drive signal. It is a figure for demonstrating the concept of the information memorize | stored in memory as information for producing | generating the unit signal shown in FIG. It is a figure for demonstrating operation | movement of a 1st waveform generation circuit. It is a figure for demonstrating a 1st original drive signal. It is a block diagram explaining the structure of a head control part. It is a figure explaining a 1st original drive signal, a 2nd original drive signal, and a required control signal. FIG. 15A is a diagram illustrating a waveform portion applied to the piezo element when a small dot is formed, a medium dot is formed, and a large dot is formed. FIG. 15B is a diagram for explaining pixel data (tone values), a waveform portion selection pattern, and selection data. It is a figure for demonstrating the concept of the measurement data table. For comparing and explaining the original drive signal generated when the theoretical DAC value is input to the first original drive signal generation unit and the second original drive signal generation unit that have generated the actual measurement data table shown in FIG. FIG. It is a figure for demonstrating the concept of the new data table input into a 1st original drive signal generation part and a 2nd original drive signal generation part. 3 is a flowchart for explaining processing of a printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printer, 20 ... Paper conveyance mechanism, 21 ... Paper feed roller, 22 ... Conveyance motor, 23 ... Conveyance roller, 24 ... Platen, 25 ... Discharge roller, 30 ... Carriage movement mechanism, 31 ... Carriage motor, 32 ... Guide Axis 33, timing belt 34, driving pulley 35 35 driven pulley 40 head unit 41 head 41A channel unit 411 nozzle plate 412 storage chamber forming substrate 412a ink storage chamber 413 ... Supply port forming substrate, 413a ... Ink supply port, 41B ... Actuator unit, 414 ... Pressure chamber forming substrate, 414a ... Pressure chamber, 415 ... Vibration plate, 416 ... Lid member, 416a ... Supply side communication port, 417 ... Piezo Element, 42 ... Needle side case member, 421 ... Ink supply needle, 43 ... Head side case member, 431 ... Substrate arrangement , 44 ... Head control board, 441 ... Connector, 45 ... Head side wiring member, 50 ... Detector group, 51 ... Linear encoder, 52 ... Rotary encoder, 53 ... Paper detector, 54 ... Paper width detector, 60 ... Printer-side controller 61 ... Interface unit 62 ... CPU 63 ... Memory 64 ... Control unit 70 ... Drive signal generation circuit 70A ... First original drive signal generation unit 71A ... First waveform generation circuit 715A ... Digital Analog converter, 716A ... voltage amplifier circuit, 72A ... first current amplifier circuit, 70B ... second original drive signal generator, 71B ... second waveform generator circuit, 715B ... digital-analog converter, 716B ... voltage amplifier circuit, 72B ... second current amplifier circuit, 81A ... first shift register, 81B ... second shift register, 82A ... first latch circuit, 82B Second latch circuit 83. Decoder 84 84 Control logic 85 Prevention circuit 86 A First level shifter 86 B Second level shifter 87 A First switch 87 B Second switch 100 Printing system 110 Computer 111 111 Host controller 112 Interface unit 113 CPU 114 Memory 120 Display device 130 Input device 131 Keyboard 132 Mouse 140 Recording / playback device 141 Flexible disk drive Device, 142 ... CD-ROM drive device, S ... paper, CTR ... controller board, IC ... ink cartridge, HC ... head controller, FC ... controller side wiring board, Nz ... nozzle, Nk ... black ink nozzle row, Nc ... Cyan ink nozzle row, Nm ... magenta Nk nozzle row, Ny ... yellow ink nozzle row, COM_A ... first drive signal, COM_B ... second drive signal, PS ... drive pulse, SS11 ... first waveform portion, SS12 ... second waveform portion, SS13 ... third waveform portion, SS14: Fourth waveform section, SS15: Fifth waveform section, SS16: Sixth waveform section, SS21: First waveform section, SS22: Second waveform section, SS23: Third waveform section, SS24: Fourth waveform section, SS25 ... 5th waveform section, SS26 ... 6th waveform section, CH_A ... 1st change signal, CH_B ... 2nd change signal, CLK ... clock signal, TIM_A ... 1st timing signal, TIM_B ... 2nd timing signal

Claims (10)

An input value of a first original drive signal generating unit that generates a first original drive signal having a unit signal for defining from the start to the end of the operation of the element for executing the operation of ejecting ink based on the drive signal Measuring the relationship between the voltage and voltage ,
A step of measuring the relationship between the second input value and the voltage of the original drive signal generator for generating a second original drive signal having the unit signal for defining the up operation end from the start of operation of the device,
Based on the relationship between the input value and voltage of the first original drive signal generator and the relationship between the input value and output of the second original drive signal generator, from the end of the operation to the start of the operation. A first reference voltage input value to the first original drive signal generation unit corresponding to the reference voltage so that reference voltages of the first original drive signal and the second original drive signal in a predetermined period are aligned; Obtaining a second reference voltage input value to the second original drive signal generation unit corresponding to the reference voltage;
Using the first reference voltage input value, the first original drive signal generation unit generates the first original drive signal, and using the second reference voltage input value, the second original drive signal generation unit Generating the second original drive signal;
Switching the first original drive signal and the second original drive signal in the predetermined period to generate the drive signal;
A drive signal generation method characterized by comprising: The drive signal generation method according to claim 1,
The method of generating a drive signal, wherein the first original drive signal and the second original drive signal are different. The drive signal generation method according to claim 1 or 2,
In the predetermined period, the drive signal generation method is characterized in that both can be changed so that the voltage increases or decreases. The drive signal generation method according to any one of claims 1 to 3 ,
The element operates based on the unit signal by a voltage output corresponding to numerical information that is periodically input,
The method of generating a drive signal, wherein the numerical information is set so that the voltages of the first original drive signal and the second original drive signal are equal in the predetermined period. The drive signal generation method according to claim 4 ,
The drive signal generation method according to claim 1, wherein the characteristic is a voltage output to the first original drive signal generation unit and the second original drive signal generation unit in response to the input value input thereto. The drive signal generation method according to claim 4 or 5 ,
The method of generating a drive signal, wherein the input value is set so that voltages of the first original drive signal and the second original drive signal in the predetermined period are each predetermined voltage. The drive signal generation method according to claim 4 or 5 ,
The first original drive signal and the second original drive signal are such that the voltage of one original drive signal in the predetermined period is aligned with the voltage of the other original drive signal in the predetermined period. A drive signal generation method, wherein the input value to be input to the original drive signal generation unit for generating an original drive signal is set. An element for executing an operation of ejecting ink based on a drive signal;
A first original drive signal generating unit that generates a first original drive signal having a unit signal for defining from the start of operation of the element to the end of operation;
A printing apparatus having a second original drive signal generating unit that generates a second original drive signal having a unit signal for defining from the operation start to the operation end of the element;
Based on the relationship between the input value and voltage of the first original drive signal generation unit and the relationship between the input value and voltage of the second original drive signal generation unit, from the end of the operation to the start of the operation. A first reference voltage input value to the first original drive signal generator corresponding to the reference voltage so that reference voltages of the first original drive signal and the second original drive signal in a predetermined period are aligned; Obtaining a second reference voltage input value to the second original drive signal generation unit corresponding to the reference voltage;
Using the first reference voltage input value, the first original drive signal generation unit generates the first original drive signal, and using the second reference voltage input value, the second original drive signal generation unit Generating the second original drive signal;
A computer program for realizing a function of generating the drive signal by switching between the first original drive signal and the second original drive signal in the predetermined period. (A) an element for executing an operation of ejecting ink based on a drive signal;
(B) a first original drive signal generation unit that generates a first original drive signal having a unit signal for defining from the operation start to the operation end of the element;
(C) a second original drive signal generating unit that generates a second original drive signal having a unit signal for defining from the operation start to the operation end of the element;
(D) Based on the relationship between the input value and voltage of the first original drive signal generation unit and the relationship between the input value and voltage of the second original drive signal generation unit, the operation is performed after the operation is completed. First reference voltage input to the first original drive signal generator corresponding to the reference voltage so that the reference voltages of the first original drive signal and the second original drive signal in a predetermined period until the start are aligned. A second reference voltage input value to the second original drive signal generation unit corresponding to the reference voltage,
Using the first reference voltage input value, the first original drive signal generation unit generates the first original drive signal, and using the second reference voltage input value, the second original drive signal generation unit Generating the second original drive signal;
A controller for generating the drive signal by switching between the first original drive signal and the second original drive signal in the predetermined period;
A printing apparatus comprising: (A) a computer;
(B) a printing apparatus connected to the computer and having the following (a) to (d):
(A) an element for executing an operation of ejecting ink based on a drive signal;
(B) a first original drive signal generation unit that generates a first original drive signal having a unit signal for defining from the operation start to the operation end of the element;
(C) a second original drive signal generating unit that generates a second original drive signal having a unit signal for defining from the operation start to the operation end of the element;
(D) Based on the relationship between the input value and voltage of the first original drive signal generation unit and the relationship between the input value and voltage of the second original drive signal generation unit, the operation is performed after the operation is completed. First reference voltage input to the first original drive signal generator corresponding to the reference voltage so that the reference voltages of the first original drive signal and the second original drive signal in a predetermined period until the start are aligned. A second reference voltage input value to the second original drive signal generation unit corresponding to the reference voltage,
Using the first reference voltage input value, the first original drive signal generation unit generates the first original drive signal, and using the second reference voltage input value, the second original drive signal generation unit Generating the second original drive signal;
A controller for generating the drive signal by switching between the first original drive signal and the second original drive signal in the predetermined period;
A printing system comprising:

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