JP4670298B2 - Drive signal generation method, printing apparatus, and printing system - Google Patents

Description

  The present invention relates to a driving signal generation method for generating a driving signal applied to an element that performs an operation for ejecting ink, a printing apparatus and a printing system having a driving signal generation unit that generates the driving signal based on generation information. About.

Some printing apparatuses that print an image on a medium apply a drive signal to a piezo element. As this type of printing apparatus, one that corrects a drive signal has been proposed. For example, in order to prevent variation in the amount of ink due to a difference in environmental temperature, a printing apparatus that corrects a drive signal in accordance with the environmental temperature has been proposed (see, for example, Patent Document 1).
JP 2000-272103 A

  Conventionally, correction of the drive signal has been performed for external factors such as environmental temperature. In other words, in the correction of the drive signal, the variation of the drive signal generation unit that generates the drive signal is not considered. However, recently, printing apparatuses have become widespread, and the same image may be printed by a plurality of printing apparatuses. In such a case, it is required to minimize individual differences among printing apparatuses. A printing apparatus that selectively applies a plurality of drive signals to one piezoelectric element has also been proposed. In such a printing apparatus, a drive signal generation unit is provided for each drive signal. However, in order to print a high-quality image, it is required that there is little variation between the drive signal generation units.

  The present invention has been made in view of such problems, and an object thereof is to increase the generation accuracy of the drive signal by the drive signal generation unit.

The main invention for achieving the object is as follows:
An adjustment signal generation step for generating an adjustment signal that is not applied to the element in a drive signal generation unit that generates a drive signal applied to the element that performs an operation for ejecting ink based on the generation information;
A signal measuring step for measuring the adjustment signal;
A generation information adjustment step of adjusting the generation information based on a measurement result of the adjustment signal;
A drive signal generation step for causing the drive signal generation unit to generate a drive signal based on the generated generation information after adjustment;
A drive signal generation method having

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

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

  That is, an adjustment signal generation step for generating an adjustment signal that is not applied to the element in a drive signal generation unit that generates a drive signal applied to the element that performs an operation for ejecting ink based on the generation information; A signal measurement step for measuring the adjustment signal, a generation information adjustment step for adjusting the generation information based on a measurement result of the adjustment signal, and a drive signal generation unit based on the generation information after adjustment. A drive signal generation method including a drive signal generation step of generating a drive signal can be realized.

  According to such a drive signal generation method, the drive signal generated in the drive signal generation step is adjusted based on the measurement result of the adjustment signal generated by the drive signal generation unit. Here, the adjustment signal is not applied to an element that performs an operation for ejecting ink. Therefore, the adjustment signal accurately reflects the characteristics of the drive signal generation unit. Therefore, the characteristics of the drive signal generation unit can be recognized with high accuracy, and as a result, the drive signal generation accuracy by the drive signal generation unit can be increased.

In this drive signal generation method, in the adjustment signal generation step, the first drive signal generation unit that generates the first drive signal based on the first generation information generates the first adjustment signal, and the second A second drive signal generation unit that generates a drive signal based on the second generation information generates a second adjustment signal, and in the signal measurement step, the first adjustment signal and the second adjustment signal are obtained. In the generation information adjustment step, the first generation information and the second generation information are adjusted based on the measurement result of the first adjustment signal and the measurement result of the second adjustment signal, and the drive signal generation is performed. In the step, the first drive signal generation unit generates the first adjustment signal based on the adjusted first generation information, and the second drive signal generation is performed based on the adjusted second generation information. To generate the second adjustment signal. It.
According to such a drive signal generation method, variations in the first drive signal generation unit and the second drive signal generation unit are adjusted, and the generation accuracy of the first drive signal and the second drive signal can be increased.

In this drive signal generation method, in the adjustment signal generation step, the pre-amplification drive signal generation unit of the drive signal generation unit generates an unamplification drive signal before amplification based on the generation information. An adjustment signal generated by the pre-amplification drive signal generation unit is measured in the signal measurement step.
According to such a drive signal generation method, since the pre-amplification drive signal generation unit generates the adjustment signal, the generated adjustment signal is also at the level before amplification. For this reason, handling of signals becomes easy.

In this drive signal generation method, in the adjustment signal generation step, the adjustment signal is supplied to a signal amplification unit of the drive signal generation unit that amplifies the drive signal before amplification generated based on the generation information. In the signal measurement step, the adjustment signal generated by the signal amplification unit is measured.
According to such a drive signal generation method, since the adjustment signal amplified in the same manner as the drive signal is a measurement target, the adjustment signal can be measured with high accuracy.

In this drive signal generation method, in the signal measurement step, the voltage of the adjustment signal is measured.
According to such a drive signal generation method, it is easy to measure the adjustment signal.

In this drive signal generation method, in the signal measurement step, the adjustment signal is measured by an adjustment signal measurement device.
According to such a drive signal generation method, it is sufficient to provide the adjustment signal measurement device with a configuration necessary for measurement. For this reason, the structure of the apparatus (for example, printing apparatus) used as measurement object can be simplified.

In this drive signal generation method, in the signal measurement step, the adjustment signal is measured by a controller that outputs the generation information.
According to such a drive signal generation method, since the adjustment signal is measured by the controller, the adjustment can be performed even after the device to be measured is shipped.

In this drive signal generation method, in the signal measurement step, the first adjustment signal generated by the first drive signal generation unit and the second adjustment signal generated by the second drive signal generation unit Are sequentially selected via a changeover switch and measured by a controller that outputs the first generation information and the second generation information.
According to such a drive signal generation method, since a plurality of adjustment signals are selected via the changeover switch, the measurement configuration can be shared.

In this drive signal generation method, in the adjustment signal generation step, the adjustment signal is generated based on generation information corresponding to the highest voltage in a unit signal for defining from the start to the end of the operation of the element. Make it.
According to such a drive signal generation method, the adjustment signal is generated based on the generation information corresponding to the highest voltage of the unit signal. Since the maximum voltage has a large influence on the ink amount, the ink amount can be adjusted with high accuracy by using the maximum voltage as an adjustment target.

In this drive signal generation method, in the adjustment signal generation step, the adjustment signal is generated based on generation information corresponding to a start voltage in a unit signal for defining from the start to the end of the operation of the element. Make it.
According to such a drive signal generation method, the adjustment is performed based on the start voltage in the unit signal, so that the generation accuracy of the drive signal can be increased. In particular, in a configuration in which a plurality of drive signals are switched, it is possible to prevent voltage fluctuation at the time of switching.

An amplification before amplification based on the first generation information of a first drive signal generation unit that generates a first drive signal applied to an element that performs an operation for ejecting ink based on the first generation information In the pre-amplification drive signal generation unit that generates the pre-drive signal or the signal amplification unit that amplifies the pre-amplification drive signal, the maximum voltage or the start voltage in the unit signal for defining from the start to the end of the operation of the element A second drive signal generation unit configured to generate a first adjustment signal not applied to the element based on the corresponding generation information, and generate a second drive signal applied to the element based on the second generation information; From the start to the end of the operation of the element, the pre-amplification drive signal generation unit that generates the pre-amplification drive signal based on the second generation information or the signal amplification unit that amplifies the pre-amplification drive signal. Prescribe An adjustment signal generation step for generating a second adjustment signal that is not applied to the element based on generation information corresponding to the highest voltage or start voltage in the unit signal, and before the amplification of the first drive signal generation unit The voltage of the first adjustment signal generated by the drive signal generation unit or the signal amplification unit and the drive signal generation unit before amplification of the second drive signal generation unit or the signal amplification unit A signal measuring step of measuring the voltage of the second adjustment signal with an adjustment signal measuring device or sequentially selecting it via a changeover switch and measuring with the controller that outputs the generation information; A generation information adjustment step of adjusting the first generation information based on the measurement result of the first adjustment signal and adjusting the second generation information based on the measurement result of the second adjustment signal; and the adjusted first Based on the generation information, the first drive signal generation unit generates the first adjustment signal, and on the basis of the adjusted second generation information, the second drive signal generation unit generates the second adjustment signal. It is also possible to realize a drive signal generation method including a drive signal generation step of generating.
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.

  In addition, an element that performs an operation for ejecting ink, a drive signal generation unit that generates a drive signal applied to the element based on generation information, and an adjustment signal that is not applied to the element in the drive signal generation unit And a controller that adjusts the generation information based on the generated adjustment signal and causes the drive signal generation unit to generate a drive signal based on the adjusted generation information. Can also be realized.

  Further, the printing system includes a printing apparatus and a printing control apparatus that controls the printing apparatus, and the printing apparatus generates an element that performs an operation for ejecting ink and a drive signal applied to the element. A drive signal generation unit that generates based on the information, and causes the drive signal generation unit to generate an adjustment signal that is not applied to the element, adjusts the generation information based on the generated adjustment signal, It is also possible to realize a printing system that includes a controller that causes the drive signal generation unit to generate a drive signal based on the generation information.

=== 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 this 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. 2A is a block diagram illustrating configurations of the computer 110 and the printer 1. FIG. 2B is a diagram schematically illustrating a part of the memory 63 included in 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 according to 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 through 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 a square grid virtually defined on the paper, and indicates a region where dots are formed. Then, the pixel data in the print data is converted into data relating to dots formed on the paper (for example, dot size data). 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. In this embodiment, the large dot corresponds to the maximum dot.

  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 side view illustrating the configuration of the printer 1 of the present embodiment. In the following description, FIG. 2A is also referred to.

  As illustrated in FIG. 2A, the printer 1 includes a paper transport mechanism 20, a carriage movement 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.

<About the paper transport mechanism 20>
The paper transport mechanism 20 corresponds to a medium transport unit that transports a medium. The paper transport mechanism 20 feeds the paper S 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.

<About the carriage moving mechanism 30>
The carriage moving mechanism 30 is for moving the carriage CR to which the head unit 40 is attached in the carriage moving direction. The carriage movement direction includes a movement direction from one side to the other side and a movement direction from the other side to the one side. 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 moving 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.

<About the head unit 40>
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. 5 is a cross-sectional view illustrating the structure of the head 41.

  For example, as shown in FIG. 4, the head unit 40 includes a head 41, a needle side case member 42, and a head side case member 43. A head control board 44 is disposed between the needle side case member 42 and the head side case member 43. A head 41 is attached to the head side case member 43. The head control board 44 and the head 41 are electrically connected by a film-like head side wiring member 45. The head side wiring member 45 is provided with a head control unit HC for controlling the head 41. The head controller HC will be described later. The thermistor 55 is provided on the head control board 44. The thermistor 55 detects the ambient temperature of the head 41. That is, the thermistor 55 can be said to be a detector for indirectly detecting the temperature of the head 41.

  The head 41 included in the head unit 40 has, for example, a structure shown in FIG. 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 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. It has a lid member 416 and a piezo element 417 formed on the surface of the diaphragm 415. In the head 41, a series of flow paths from the ink storage chamber 412a to the nozzle Nz through the pressure chamber 414a is formed. 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. Accordingly, in the head 41, the piezo element 417 corresponds to an element that performs an operation for ejecting ink.

  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.

<Regarding the detector group 50>
The detector group 50 is for monitoring the status of the printer 1. As shown in FIGS. 3A, 3B, and 4, the detector group 50 includes a linear encoder 51, a rotary encoder 52, a paper detector 53, a paper width detector 54, a thermistor 55, 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 for detecting the width of the paper S to be printed. As described above, the thermistor 55 is provided on the head control board 44 and detects the ambient temperature of the head 41.

<About the printer-side controller 60>
The printer-side controller 60 controls the printer 1. The printer-side controller 60 corresponds to a controller that outputs a DAC value (digital / analog conversion value), which is a kind of generation information, to the drive signal generation circuit 70. Then, the printer-side controller 60 outputs the DAC value to cause the drive signal generation circuit 70 to generate the drive signal COM (first drive signal COM_A, second drive signal COM_B, see FIG. 11A). The DAC value and the drive signal COM will be described later.

  As shown in FIG. 2A, 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. In the present embodiment, as shown in FIG. 2B, a part of the memory 63 is used as a program storage area 63a, a waveform storage area 63b, and an adjustment value storage area 63c. The program storage area 63a is an area for storing computer programs. The waveform storage area 63b is an area in which waveform data for generating the drive signal COM is stored. The adjustment value storage area 63c stores adjustment values (described later) for adjusting variations between the first waveform generation circuit 71A and the second waveform generation circuit 71B (see FIG. 6) of the drive signal generation circuit 70. It is an area to be

  And CPU62 controls each control object part according to the computer program memorize | stored in the program storage area 63a of the memory 63. FIG. For example, the CPU 62 controls the paper transport mechanism 20 and the carriage moving mechanism 30 via the control unit 64. Further, the CPU 62 outputs a head control signal for controlling the operation of the head 41 to the head controller HC, and outputs a control signal for generating the drive signal COM to the drive signal generation circuit 70.

<About the drive signal generation circuit 70>
The drive signal generation circuit 70 generates a drive signal COM that is used in common. 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 drive signal generation unit 70A that generates the first drive signal COM_A and a second drive signal generation unit 70B that generates the second drive signal COM_B. The first drive signal generation unit 70A includes a first waveform generation circuit 71A and a first current amplification circuit 72A, and the second drive signal generation unit 70B includes a second waveform generation circuit 71B and a second current amplification circuit 72B. Have The first waveform generation circuit 71A and the second waveform generation circuit 71B have the same configuration, and the first current amplification circuit 72A and the second current amplification circuit 72B have the same configuration. For this reason, the following description is mainly given to the first drive signal generation unit 70A, that is, the first waveform generation circuit 71A and the first current amplification circuit 72A.

  FIG. 7A is a block diagram for explaining the configuration of the first waveform generation circuit 71A and the second waveform generation circuit 71B. In this figure, the configuration of the second waveform generation circuit 71B is indicated by parenthesized symbols. FIG. 7B is a diagram for explaining the relationship between the DAC value input to the digital-analog converter 711A (711B) and the output voltage from the voltage amplification circuit 712A (712B).

  The first waveform generation circuit 71A includes a digital-analog converter (D / A converter) 711A and a voltage amplification circuit 712A. The digital-analog converter 711A is an electric circuit that outputs a voltage signal corresponding to the DAC value. This DAC value is information for instructing a voltage (hereinafter also referred to as an output voltage) to be output from the voltage amplification circuit 712A. That is, the DAC value is a kind of generation information for generating the drive signal COM. The DAC value is output from the CPU 62 based on the waveform data stored in the waveform storage area 63b. In this embodiment, the DAC value is composed of 10-bit data. For convenience, the DAC value is indicated by a hexadecimal number with h added to the end.

  The voltage amplification circuit 712A amplifies the output voltage from the digital-analog converter 711A to a voltage suitable for the operation of the piezo element 417. In the voltage amplification circuit 712A of this embodiment, the output voltage from the digital-analog converter 711A is amplified to a maximum of 40 and several volts. Then, the amplified output voltage is output to the first current amplification circuit 72A as the control signal S_Q1 and the control signal S_Q2.

  For example, in the example shown in FIG. 7B, when the DAC value input to the digital-analog converter 711A is “24Eh” in hexadecimal (in the case of “1001001110” in binary), the DAC value after being amplified by the voltage amplification circuit 712A The output voltage is 25.00V. Further, when the DAC value input to the digital-analog converter 711A is “0h” in hexadecimal (in the case of “0000000” in binary), the output voltage after being amplified by the voltage amplification circuit 712A is 1.40V. When the input DAC value is “3FF” in hexadecimal (in the case of “1111111111” in binary), the output voltage after being amplified by the voltage amplification circuit 712A is 42.32V. That is, the illustrated first drive signal generator 70A has a configuration in which the minimum output voltage is 1.40V, and when the DAC value increases by one, the output voltage increases by 0.04V.

  Therefore, in this embodiment, the digital-analog converter 711A corresponds to a pre-amplification drive signal generation unit, and generates a pre-amplification drive signal before voltage amplification or current amplification based on a DAC value as generation information. The voltage amplification circuit 712A and the first current amplification circuit 72A correspond to a signal amplification unit, and amplify the power (voltage and current) of the pre-amplification drive signal generated based on the DAC value (generation information). .

  In addition, a measurement terminal 713A is provided between the output of the digital-analog converter 711A and the input of the voltage amplification circuit 712A. The measurement terminal 713A has the same voltage as the output voltage of the digital-analog converter 711A. In other words, it is a terminal to which the drive signal before amplification described above is output. The measurement terminal 713A is branched from a signal line that electrically connects the output of the digital-analog converter 711A and the input of the voltage amplification circuit 712A. At the time of measuring the pre-amplification drive signal, the measurement probe 211 (see FIG. 15) is brought into contact with the measurement terminal 713A. The measurement of the pre-amplification drive signal will be described later.

<Specific Example of Operation of First Drive Signal Generation Unit 70A>
Next, a specific example of the operation of the first drive signal generator 70A will be described. Here, FIG. 8A is a diagram for explaining a part of the generated drive signal COM. FIG. 8B is a diagram for explaining the operation of dropping the output voltage of the first current amplification circuit 72A from the voltage V1 to the voltage V4.

  The CPU 62 of the printer-side controller 60 first obtains an output voltage for each update cycle τ based on a parameter for generating the drive signal COM. Taking the drive pulse PS ′ shown in FIG. 8A as an example, the parameters include a drive voltage Vh, a ratio defining the relationship between the drive voltage Vh and the reference voltage Vc, a time PWh1 for maintaining the intermediate voltage VC, A time PWd1 for dropping the voltage from the intermediate voltage VC to the lowest voltage VL with a constant slope, a time PWh2 for maintaining the lowest voltage VL, and a time PWc1 for raising the voltage with a constant slope from the lowest voltage VL to the highest voltage VH Then, there is a time PWh3 for maintaining the maximum voltage VH, a time PWd2 for dropping the voltage from the maximum voltage VH to the intermediate voltage VC at a constant slope, and a time PWh4 for maintaining the intermediate voltage VC.

  Here, the drive voltage Vh is a voltage difference between the highest voltage VH and the lowest voltage VL in the drive pulse PS ′. In other words, this corresponds to the difference between the lowest potential (potential determined by the lowest voltage VL) and the highest potential (potential determined by the highest voltage VH) of the piezo element 417 when the drive pulse PS ′ is applied. The reference voltage Vc defines a deformation state that serves as a reference for the piezo element 417. In the present embodiment, this reference voltage Vc is set to 40% (ratio 0.4) of the drive voltage Vh. The intermediate voltage VC is a voltage obtained by adding the reference voltage Vc to the minimum voltage VL. The maximum voltage VH is a voltage obtained by adding the drive voltage Vh to the minimum voltage VL. These parameters are stored in the waveform storage area 63b of the memory 63. Regarding the drive voltage Vh, a reference voltage value (also referred to as a reference drive voltage Vhs for convenience) is stored in the waveform storage area 63b. That is, the drive voltage Vh that is actually used is determined by correcting the reference drive voltage Vhs based on the ambient temperature of the head 41 and the like.

  The CPU 62 acquires the ambient temperature of the head 41 from the output of the thermistor 55 at a predetermined timing, for example, paper feed timing, and determines the drive voltage Vh based on the acquired ambient temperature. When the drive voltage Vh is determined, the CPU 62 calculates a reference voltage Vc, an intermediate voltage VC, and a maximum voltage VH. And CPU62 calculates | requires the output voltage for every update period (tau) using time PWh1-time PWh4 mentioned above. The update period τ is, for example, 0.1 μs (clock CLK = 10 MHz) to 0.05 μs (clock CLK = 20 MHz). Then, based on the obtained output voltage for each update cycle τ, a DAC value for each update cycle τ is determined and stored, for example, in a work area (not shown) of the memory 63.

  When generating the drive signal COM, the DAC value for each update period τ is sequentially output to the digital-analog converter 711A. In the example of FIG. 8B, the DAC value corresponding to the voltage V1 is output at the timing t (n) defined by the clock CLK. As a result, the voltage V1 is output from the voltage amplification circuit 712A at the period τ (n). Until the update period τ (n + 4), the DAC values corresponding to the voltage V1 are sequentially output, and the voltage V1 is continuously output from the voltage amplifier circuit 712A. At the timing t (n + 5), a DAC value corresponding to the voltage V2 is output. As a result, the output of the voltage amplification circuit 712A drops from the voltage V1 to the voltage V2 in the cycle τ (n + 5). Similarly, at the timing t (n + 6), the DAC value corresponding to the voltage V3 is output. As a result, the output of the voltage amplification circuit 712A drops from the voltage V2 to the voltage V3 in the cycle τ (n + 6). Similarly, since the DAC value is output, the voltage output from the voltage amplifier circuit 712A gradually decreases. Then, in the period τ (n + 10), the output of the voltage amplification circuit 712A drops to the voltage V4.

<Regarding First Current Amplifier 72A>
Next, the first current amplifier circuit 72A will be described. Here, FIG. 9 is a diagram illustrating the configuration of the current amplifier circuits 72A and 72B.

  The first current amplifying circuit 72A is a circuit for supplying a sufficient current so that a large number of piezo elements 417 can operate without trouble. Therefore, the voltage amplified by the voltage amplification circuit 712A is maintained at the same voltage after current amplification. The illustrated first current amplifying circuit 72A includes a first transistor pair 721A that generates heat as the voltage of the first drive signal COM_A changes. The first transistor pair 721A includes an NPN transistor Q1 and a PNP transistor Q2 whose emitter terminals are connected to each other. The NPN transistor Q1 is a transistor that operates when the voltage of the drive signal COM rises. The NPN transistor Q1 has a collector connected to the power supply and an emitter connected to the output signal line of the first drive signal COM_A. The PNP transistor Q2 is a transistor that operates when the voltage drops. The PNP transistor Q2 has a collector connected to the ground (earth) and an emitter connected to the output signal line of the first drive signal COM_A. Note that the voltage at the portion where the emitters of the NPN transistor Q1 and the PNP transistor Q2 are connected to each other (the voltage of the first drive signal COM_A) is fed back to the voltage amplifier circuit 712A, as indicated by the symbol FB1. Yes.

  The operation of the first current amplification circuit 72A, that is, the first transistor pair 721A is controlled by the output voltage from the first waveform generation circuit 71A. For example, when the output voltage is in the rising state, the NPN transistor Q1 is turned on by the control signal S_Q1. Along with this, the voltage of the first drive signal COM_A also increases. On the other hand, when the output voltage is in a drop state, the PNP transistor Q2 is turned on by the control signal S_Q2. Along with this, the voltage of the first drive signal COM_A also drops. Note that when the output voltage is constant, both the NPN transistor Q1 and the PNP transistor Q2 are turned off. As a result, the first drive signal COM_A becomes a constant voltage.

<Regarding Second Waveform Generation Circuit 71B and Second Current Amplification Circuit 72B>
Next, the second waveform generation circuit 71B and the second current amplification circuit 72B will be briefly described. As described above, the configuration of the second waveform generation circuit 71B is the same as the configuration of the first waveform generation circuit 71A, and the configuration of the second current amplification circuit 72B is the same as the configuration of the first current amplification circuit 72A. . That is, the second waveform generation circuit 71B includes a digital-analog converter 711B and a voltage amplification circuit 712B. The second current amplifier circuit 72B includes a second transistor pair 721B that generates heat as the voltage of the second drive signal COM_B changes. The second transistor pair 721B includes an NPN transistor Q1 and a PNP transistor Q2 whose emitter terminals are connected to each other. A measurement terminal 713B is provided between the output of the digital-analog converter 711B and the input of the voltage amplification circuit 712B. Of these configurations, the digital-analog converter 711B corresponds to a pre-amplification drive signal generation unit. The voltage amplification circuit 712B and the second current amplification circuit 72B correspond to a signal amplification unit.

<About the generated drive signal COM>
Next, the drive signal generated by the drive signal generation circuit 70 will be described. The exemplified drive signal generation circuit 70 generates the first drive signal COM_A and the second drive signal COM_B shown in FIG. 11A. That is, the first waveform generation circuit 71A generates the first drive signal COM_A based on the first DAC value (corresponding to the first generation information). The second waveform generation circuit 71B generates the second drive signal COM_B based on the second DAC value (corresponding to the second generation information).

  The first drive signal COM_A includes a first waveform section SS11a generated in the period T1 in the repetition period T, a second waveform section SS12a generated in the period T2, and a third waveform section SS13a generated in the period T3. Have. Here, the first waveform section SS11a has a drive pulse PS1. The second waveform section SS12a has a drive pulse PS2, and the third waveform section SS13a has a drive pulse PS3. The drive pulse PS1 and the drive pulse PS3 are applied to the piezo element 417 when a large dot is formed, and have the same waveform. That is, the drive pulse PS1 and the drive pulse PS3 correspond to unit signals that define from the start to the end of the operation for ejecting ink when forming a large dot. The drive pulse PS2 is applied to the piezo element 417 when a small dot is formed. The drive pulse PS2 corresponds to a unit signal that defines from the start to the end of the operation for ejecting ink when forming a small dot. By applying this drive pulse PS2 to the piezo element 417, a small ink droplet is ejected from the head 41 (corresponding nozzle Nz).

  The second drive signal COM_B includes a first waveform section SS21a generated in the period T1, a second waveform section SS22a generated in the period T2, and a third waveform section SS23a generated in the period T3. In the second drive signal COM_B, the first waveform section SS21a has a drive pulse PS4, and the second waveform section SS22a has a drive pulse PS5. Here, the drive pulse PS4 is applied to the piezo element 417 when the medium dot is formed. By applying this drive pulse PS4 to the piezo element 417, a medium ink droplet is ejected from the head 41. Therefore, the drive pulse PS4 corresponds to a unit signal that defines from the start to the end of the operation for ejecting ink when forming a medium dot. The drive pulse PS5 is applied to the piezo element 417 when a large dot is formed. That is, this drive pulse PS5 also corresponds to a unit signal. The drive pulse PS5 has the same waveform as the drive pulse PS1 and the drive pulse PS3. In the second drive signal COM_B, the third waveform section SS23a generated in the period T3 is a constant voltage signal that is constant at the intermediate voltage VC.

<About the head controller HC>
Next, the head controller HC will be described. Here, FIG. 10 is a block diagram illustrating the configuration of the head controller HC. As shown in FIG. 10, 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. 86A, second level shifter 86B, first switch 87A, and 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. Then, the upper bit group of the pixel data is set in the first shift register 81A, and the lower bit group is set in the second shift register 81B. 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, the first latch circuit 82A latches the upper bit group of the pixel data, and the second latch circuit 82B latches the lower bit group 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 decoder 83 performs decoding based on the upper bits and lower bits of the pixel data, and outputs a switch control signal for controlling on / off of the first switch 87A and the second switch 87B. The switch control signal is output based on a combination of selection data stored in the control logic 84 and pixel data latched by the first latch circuit 82A and the second latch circuit 82B. The selection data is stored in the control logic 84 separately into first selection data corresponding to the first drive signal COM_A and second selection data corresponding to the second drive signal COM_B. The first selection data for the first drive signal COM_A is output through the control signal line group CTL_A, and the second selection data for the second drive signal COM_B is output through the control signal line group CTL_B.

  In the present embodiment, the first selection data is constituted by 3-bit data corresponding to each of the first waveform portion SS11a to the third waveform portion SS13a constituting the first drive signal COM_A. Similarly, the second selection data is configured by 3-bit data corresponding to each of the first waveform section SS21a to the third waveform section SS23a configuring the second drive signal COM_B. The first selection data and the second selection data are data for each gradation (non-formed, small dot, medium dot, large dot), and pass through corresponding signal lines of the control signal line groups CTL_A and CTL_B. Data of each gradation is output. Then, the decoder 83 acquires the first selection data and the second selection data corresponding to the latched pixel data (gradation value) through the control signal line group CTL_A and the control signal line group CTL_B, and receives the switch control signal. Output (to be described later).

  The switch control signal output from the decoder 83 is input to the first level shifter 86A and the second level shifter 86B after passing through the prevention circuit 85. That is, a switch control signal (also referred to as a first switch control signal for convenience) corresponding to the first selection data is input to the first level shifter 86A, and a switch control signal corresponding to the second selection data (second switch control for convenience). Is also input to the second level shifter 86B. The first level shifter 86A and the second level shifter 86B function as a voltage amplifier. When the corresponding switch control signal is [1], the first level shifter 86A and the second level shifter 86B receive ON signals boosted to voltages that drive the first switch 87A and the second switch 87B. Output.

  The first 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 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 drive signal COM to be generated. Then, the waveform portions SS11a to SS13a constituting the first drive signal COM_A and the waveform portions SS21a to SS23a constituting the second drive signal COM_B are selectively applied to the piezo element 417.

  The first selection data described above controls the operation of the first switch 87A, and the second selection data controls the operation of the second switch 87B. That is, when the first selection data is [1], the decoder 83 sets the first switch control signal to [1] over the period. Then, the first level shifter 86A outputs an ON signal boosted to several tens of volts to the first switch 87A over a period in which the first switch control signal is [1]. As a result, the first switch 87A is turned on, and the first drive signal COM_A is applied to the piezo element 417. When the first selection data is [0], the decoder 83 sets the first switch control signal to [0] over the period. Accordingly, an electrical signal for operating the first switch 87A is not output from the first level shifter 86A. As a result, the first drive signal COM_A is not applied to the piezo element 417. The decoder 83 sets the second switch control signal to [1] when the second selection data is [1], and sets the second switch control signal to [0] when the second selection data is [0]. To. Then, when the input second switch control signal is [1], the second level shifter 86B outputs an ON signal boosted to several tens of volts to the second switch 87B, and the second switch control signal is [0]. In this case, an electrical signal for operating the second switch 87B is not output. Then, the second switch 87B is turned on by the output of the on signal, and the second drive signal COM_B is applied to the piezo element 417.

  The piezo element 417 behaves like a capacitor. For this reason, when the application of the drive signal COM is stopped, the piezo element 417 maintains the potential immediately before the stop. 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.

  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 drive signal COM_A and the second 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.

<About gradation control>
Next, gradation control in the printer 1 will be described. Here, FIG. 11A is a diagram illustrating the first drive signal COM_A, the second drive signal COM_B, and necessary control signals. FIG. 11B is a diagram illustrating pixel data (gradation values), a waveform portion selection pattern, and selection data. FIG. 12 is a diagram illustrating a waveform portion applied to the piezo element 417 when forming a small dot, when forming a medium dot, and when forming a large dot. In this gradation control, the operations of the first switch 87A and the second switch 87B are controlled based on the switch control signal as described above.

  First, the case of forming small dots (pixel data [01]) will be described. In this case, the decoder 83 selects the first selection data [010] and the second selection data [000] based on the pixel data [01] indicating the formation of small dots, and the first switch control signal and the second switch control. Output a signal. Thereby, as shown in the upper part of FIG. 12, the first drive signal COM_A is applied to the piezo element 417 in the period T2, and the second drive signal COM_B is not applied to the piezo element 417 over the periods T1 to T3. Accordingly, the drive pulse PS2 included in the second waveform portion SS12a of the first drive signal COM_A is applied to the piezo element 417, and an amount of ink corresponding to a small dot is ejected from the nozzle Nz.

  Next, the case of formation of medium dots (pixel data [10]) will be described. In this case, the decoder 83 selects the first selection data [000] and the second selection data [100] based on the pixel data [10] indicating the formation of the medium dot, and the first switch control signal and the second switch control are selected. Output a signal. Accordingly, as shown in the middle stage of FIG. 12, the second drive signal COM_B is applied to the piezo element 417 in the period T1, and the first drive signal COM_A is not applied to the piezo element 417 over the periods T1 to T3. Accordingly, the drive pulse PS4 included in the first waveform section SS21a is applied to the piezo element 417, and an amount of ink corresponding to the medium dot is ejected from the nozzle Nz.

  Next, the case of large dot formation (pixel data [11]) will be described. In this case, the decoder 83 selects the first selection data [101] and the second selection data [010] based on the pixel data [11] indicating the formation of large dots, and the first switch control signal and the second switch control. Output a signal. Thereby, as shown in the lower part of FIG. 12, the first drive signal COM_A is applied to the piezo element 417 in the periods T1 and T3, and the second drive signal COM_B is applied to the piezo element 417 in the period T2. Accordingly, the drive pulse PS1 included in the first waveform section SS11a of the first drive signal COM_A, the drive pulse PS5 included in the second waveform section SS22a of the second drive signal COM_B, and the third waveform section SS13a of the first drive signal COM_A are included. The drive pulse PS3 is applied to the piezo element 417 in sequence, and an amount of ink corresponding to a large dot is ejected from the nozzle Nz.

  In the case of no dot formation (pixel data [00]), the first selection data is [000] and the second selection data is [000]. In this case, neither the first drive signal COM_A nor the second drive signal COM_B is applied to the piezo element 417. Therefore, ink is not ejected from the nozzle Nz.

<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.
Here, FIG. 13 is a flowchart for explaining the printing operation. The illustrated printing operation includes a print command receiving operation (S10), a paper feeding operation (S20), a dot forming operation (S30), a conveying operation (S40), a paper discharge determination (S50), a paper discharge process (S60), and It has a print end determination (S70). Hereinafter, each operation will be briefly described.

The print command receiving operation (S10) is an operation 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.
The paper feeding operation (S20) is an operation for moving the paper S to be printed and positioning it at a printing start position (so-called cueing position). In this operation, 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 forming operation (S30) is an operation for forming dots on the paper S. In this operation, the printer-side controller 60 drives the carriage motor 31 and outputs a control signal to the drive signal generation circuit 70 and the head 41. Thus, ink is ejected from the nozzles Nz while the head 41 is moving, and dots are formed on the paper S.
The transport operation (S40) is an operation for moving the paper S in the transport direction. In this operation, 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 (S50) is an operation 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 (S60) is a process of discharging the paper S, and is performed on 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.
The print end determination (S70) is a determination as to whether or not to continue printing. This determination is also made by the printer-side controller 60.

=== Outline of the Embodiment ===
<Variation of drive signal generation circuit>
By the way, for the purpose of explaining the configuration of the printer 1, the above description has the characteristics of the first drive signal generation unit 70 </ b> A included in the drive signal generation circuit 70 and the characteristics of the second drive signal generation unit 70 </ b> B. It is based on the assumption. However, in practice, the characteristics of the first drive signal generator 70A and the characteristics of the second drive signal generator 70B may vary. Hereinafter, problems in this case will be described. Here, FIG. 14A is a diagram illustrating the drive pulse generated by the first drive signal generation unit 70A. FIG. 14B is a diagram illustrating an example of the output voltage in the first drive signal generation unit 70A. The output voltage in FIG. 14B corresponds to the drive pulse PS1 in FIG. 14A. FIG. 14C is a diagram illustrating the drive pulse PS5 generated by the second drive signal generation unit 70B. FIG. 14D is a diagram illustrating an example of an output voltage in the second drive signal generation unit 70B. The output voltage in FIG. 14D corresponds to the drive pulse PS5 in FIG. 14C. FIG. 14E is a diagram for explaining the difference in size of the dots DT formed using the drive pulse PS1 of FIG. 14A and the drive pulse PS5 of FIG. 14C.

  In this example, the second drive signal generation unit 70B has a characteristic of outputting a higher voltage than the first drive signal generation unit 70A. That is, the first drive signal generation unit 70A outputs a voltage of 1.40V when the DAC value “0h” is input, and outputs a voltage of 26.40V when the DAC value “271h” is input. Here, if the DAC value “0h” corresponds to the lowest voltage VL and the DAC value “271h” corresponds to the highest voltage VH, the drive voltage Vh_A of the drive pulse PS1 is 25.00V. The second drive signal generation unit 70B outputs a voltage of 1.42V when the DAC value “0h” is input, and outputs a voltage of 26.80V when the DAC value “271h” is input. In this case, the drive voltage Vh_B of the drive pulse PS5 is 25.38V. The difference between the drive voltages Vh_A and Vh_B appears as a difference in the magnitude of pressure fluctuation with respect to the ink in the pressure chamber 414a when ink is ejected.

  As a result, as shown in FIG. 14E, the dot DT (PS5) formed by the drive pulse PS is larger than the dot DT (PS1) formed by the drive pulse PSPS1. This difference in the size of the dots is not preferable because it can cause deterioration in image quality. For example, when a large dot is formed, the drive pulse PS3 is also applied to the piezo element 417, and this drive pulse PS3 is generated by the first drive signal generator 70A. For this reason, the drive pulse PS3 has the same shape as the drive pulse PS1. Then, as shown by a dotted line in FIG. 14E, among the three dots constituting the large dot, the central dot DT (PS5) becomes larger than the other dots DT (PS1) and DT (PS3). As a result, a large dot composed of these three dots is deformed, which may impair image quality. In the present embodiment, the following configuration is adopted to prevent such a problem.

That is, when generating the drive signal COM (first drive signal COM_A, second drive signal COM_B), the following processes 1 to 4 are performed.
1. An adjustment signal AS (not applied to the piezo element 417) is applied to the drive signal generators 70A and 70B that generate the first drive signal COM_A and the second drive signal COM_B applied to the piezo element 417 based on the DAC value (generation information). First adjustment signal AS_A (FIG. 17A) and second adjustment signal AS_B (FIG. 17B)) are generated (adjustment signal generation step).
2. The adjustment signal AS generated by the drive signal generation units 70A and 70B is measured (signal measurement step).
3. The DAC value is adjusted based on the measurement result of the adjustment signal AS (generation information adjustment step).
4). Based on the adjusted DAC value, the drive signal generation units 70A and 70B generate the first drive signal COM_A and the second drive signal COM_B (drive signal generation step).

  By adopting such a procedure, the first drive signal COM_A and the second drive signal COM_B generated in the drive signal generation step are the adjustment signals AS (first adjustment signals) generated by the drive signal generation units 70A and 70B. Adjustment is performed based on the measurement result of the signal AS_A and the second adjustment signal AS_B). Here, the adjustment signal AS is not applied to the piezo element 417. For this reason, the adjustment signal AS accurately reflects the characteristics of the drive signal generators 70A and 70B. Therefore, the characteristics of the drive signal generation units 70A and 70B can be recognized with high accuracy, and as a result, the generation accuracy of the first drive signal COM_A and the second drive signal COM_B by the drive signal generation units 70A and 70B can be increased.

=== Setting of adjustment value ===
<About equipment used to set adjustment values>
First, devices used for setting adjustment values will be described. FIG. 15 is a block diagram illustrating devices used for setting adjustment values. In addition, about the apparatus already demonstrated, since the same code | symbol is attached | subjected, description is abbreviate | omitted.

  The adjustment value is set using the adjustment value setting device 200. The adjustment value setting device 200 has a function of causing the drive signal generators 70A and 70B to generate an adjustment signal AS, a function of measuring the generated adjustment signal AS, and a function of writing a predetermined adjustment value in the printer 1. And have. Therefore, the adjustment value setting device 200 corresponds to an adjustment signal AS generation control device, an adjustment signal AS measurement device, and an adjustment value writing device. The adjustment value setting apparatus 200 includes a printer-side interface unit 201, a probe-side interface unit 202, an analog / digital conversion unit (A / D conversion unit) 203, a CPU 204, a memory 205, and a measurement probe 211. Have.

  The printer side interface unit 201 is communicably connected to an interface unit 61 included in the printer side controller 60. Accordingly, the CPU 204 of the adjustment value setting device 200 can output a control signal to the printer-side controller 60 via the printer-side interface unit 201. The probe-side interface unit 202 is for inputting an electrical signal from the measurement probe 211. The analog-digital conversion unit 203 converts an electrical signal from the measurement probe 211 input via the probe-side interface unit 202 into a digital value corresponding to the voltage value. The converted digital value is output to the CPU 204.

  The CPU 204 is an arithmetic processing device for performing overall control of the adjustment value setting device 200. The memory 205 is used to secure an area for storing a computer program used by the CPU 204, a work area, and the like, and includes a RAM, an EEPROM, a ROM, a magnetic disk device, and the like. The CPU 204 performs various controls according to the computer program stored in the memory 205. The computer program stored in the memory 205 includes an adjustment value setting program. This adjustment value setting program is for executing adjustment value setting processing. By executing this adjustment value setting process, an adjustment value for the printer 1 is determined and stored in the adjustment value storage area 63c. Therefore, the adjustment value setting program has a code for executing the adjustment value setting process.

<Regarding the adjustment value setting process>
Next, the adjustment value setting process will be described. FIG. 16 is a flowchart showing the flow of the adjustment value setting process. FIG. 17A is a diagram illustrating a first adjustment signal AS_A that is generated by the first drive signal generation unit 70A. FIG. 17B is a diagram illustrating the second adjustment signal AS_B that is generated by the second drive signal generation unit 70B.

  The adjustment value setting process is performed for the printer 1 that has been assembled. In performing the adjustment value setting process, the adjustment value setting device 200 and the printer 1 are connected to be communicable. For example, the interface unit 61 of the printer-side controller 60 and the printer-side interface unit 201 of the adjustment value setting device 200 are connected by a communication cable or the like. Next, the adjustment value setting device 200 is caused to execute an adjustment value setting program. By executing this adjustment value setting program, the step of generating the adjustment signal AS (S110), the step of measuring the adjustment signal AS (S120), the step of calculating the adjustment value (S130), and the step of writing the adjustment value ( S140) is performed. Hereinafter, these steps will be described.

  In the step of generating the adjustment signal AS (S110), the drive signal generation circuit 70 is caused to generate the adjustment signal AS. That is, the first drive signal generator 70A generates the first adjustment signal AS_A, and the second drive signal generator 70B generates the second adjustment signal AS_B. Here, the adjustment signal AS is a signal generated for recognizing the characteristics of the drive signal generation circuit 70, and is not applied to the piezo element 417.

  By the way, in general feedback control, characteristics are grasped in a state where the apparatus is actually operated. When this concept is applied, it may be considered that the printer 1 is to apply the first drive signal COM_A and the second drive signal COM_B to the piezo element 417 and grasp the characteristics in a state where ink is actually ejected. However, in the present embodiment, adjustment is performed using the adjustment signal AS that is not applied to the piezo element 417. This is because if the characteristics are grasped using the first drive signal COM_A and the second drive signal COM_B, the first drive signal COM_A and the second drive signal COM_B are distorted with application to the piezo element 417. . Further, the piezo element 417 is provided for each nozzle Nz. For this reason, the degree to which the first drive signal COM_A and the second drive signal COM_B are distorted changes depending on the number of nozzles Nz from which ink is ejected. Under such circumstances, adjustment is performed using the adjustment signal AS that is not applied to the piezo element 417.

  The first adjustment signal AS_A and the second adjustment signal AS_B in the present embodiment are generated based on the DAC value corresponding to the highest voltage VH in the drive pulse PS as a unit signal. As described above, the first adjustment signal AS_A and the second adjustment signal AS_B are generated based on the DAC value corresponding to the maximum voltage VH because the maximum voltage VH has an influence on the ink ejection amount. This is because it is large. Therefore, by setting the maximum voltage VH as an adjustment target, the ink amount can be adjusted with high accuracy.

  14A to 14D, the DAC value “271h” is output to the digital-analog converter 711A of the first drive signal generation unit 70A to generate the first adjustment signal AS_A. Similarly, the DAC value “271h” is output to the digital-analog converter 711B of the second drive signal generation unit 70B to generate the second adjustment signal AS_B.

  For this reason, the CPU 204 of the adjustment value setting device 200 outputs a control command to the printer 1. Based on this control command, the CPU 62 of the printer-side controller 60 outputs a DAC value (first generation information) of “271h” to the digital-analog converter 711A of the first drive signal generation unit 70A. Similarly, the CPU 62 outputs the DAC value (second generation information) of “271h” to the digital-analog converter 711B of the second drive signal generation unit 70B. At this time, since both the first switch 87A and the second switch 87B are in the OFF state, the first adjustment signal AS_A and the second adjustment signal AS_B can be output simultaneously. The DAC value is an example and is not limited to this value.

  The first adjustment signal AS_A generated in this way is a constant signal at a predetermined voltage pVH_A (see FIG. 17A), and the second adjustment signal AS_B is at a predetermined voltage pVH_B (see FIG. 17B). It becomes a constant signal. If the characteristics of the digital-analog converter 711A of the first drive signal generator 70A and the characteristics of the digital-analog converter 711B of the second drive signal generator 70B are the same, the voltage of the first adjustment signal AS_A The voltage of the second adjustment signal AS_B has the same value. On the other hand, if the characteristics of the digital-analog converters 711A and 711B are different, the voltage pVH_A of the first adjustment signal AS_A and the voltage pVH_B of the second adjustment signal AS_B show different values. Therefore, the voltage pVH_A of the first adjustment signal AS_A and the voltage pVH_B of the second adjustment signal AS_B are a kind of information indicating the characteristics of the first drive signal generation unit 70A and the second drive signal generation unit 70B. I can say that. The signals output from the digital-analog converters 711A and 711B are those before the voltage is amplified by the voltage amplification circuits 712A and 712B. For this reason, the voltage pVH_A of the first adjustment signal AS_A and the voltage pVH_B of the second adjustment signal AS_B are sufficiently lower than the maximum voltage VH in the drive pulse PS. For example, the maximum voltage VH in the drive pulse PS is 20 to 30 V, whereas the voltage pVH_A of the first adjustment signal AS_A and the voltage pVH_B of the second adjustment signal AS_B are about 1V to 2V. .

  In the step (S120) of measuring the adjustment signal AS, the adjustment signal AS is measured by the adjustment value setting device 200. In the present embodiment, the voltage of the adjustment signal AS is measured. Here, the voltage is measured because digital conversion can be easily performed and measurement is easy. Further, the adjustment signal AS to be measured is the signal before being amplified by the voltage amplification circuits 712A and 712B as described above. For this reason, the voltage value is sufficiently lower than the maximum voltage VH in the drive signal COM. Also in this respect, handling of signals becomes easy and measurement can be performed easily.

  When measuring the first adjustment signal AS_A, the measurement probe 211 is brought into contact with the measurement terminal 713A on the first drive signal generation unit 70A side. As a result, the voltage of the first adjustment signal AS_A is input through the probe-side interface unit 202. The input voltage pVH_A of the first adjustment signal AS_A is converted into a digital value by the analog-digital converter 203 and output to the CPU 204. The CPU 204 recognizes the voltage pVH_A of the first adjustment signal AS_A based on the digital value from the analog-digital conversion unit 203. When measuring the second adjustment signal AS_B, the measurement probe 211 is brought into contact with the measurement terminal 713B on the second drive signal generation unit 70B side. Accordingly, the voltage pVH_B of the second adjustment signal AS_B is measured in the same procedure as that for measuring the first adjustment signal AS_A. That is, the CPU 204 recognizes the voltage pVH_B of the second adjustment signal AS_B. The voltage pVH_A of the first adjustment signal AS_A and the voltage pVH_A of the second adjustment signal AS_B recognized in this way are stored in the memory 205 of the adjustment value setting device 200. For example, it is stored in a work area (not shown) assigned to a partial area of the memory 205.

  In the step of calculating an adjustment value (S130), based on the measured voltage value of the first adjustment signal AS_A and the voltage value of the second adjustment signal AS_B, the first adjustment value for the first drive signal generator 70A. And the second adjustment value for the second drive signal generator 70B are calculated. In this step, the CPU 204 of the adjustment value setting device 200 causes the measured voltage value of the first adjustment signal AS_A, the voltage value of the second adjustment signal AS_B, and the voltage specified in the step of generating the adjustment signal AS. Find the difference from the value (designed voltage value). In this example, the difference from the output voltage before voltage amplification corresponding to the DAC value “271h” is obtained. When the voltage difference is obtained, the CPU 204 of the adjustment value setting device 200 calculates an adjustment value corresponding to the voltage difference. This adjustment value is information indicating a voltage difference from the design value in the DAC value to be measured. As the adjustment value, for example, numerical information indicating a voltage difference from the design value and information on a DAC value indicating the voltage difference from the design value can be appropriately determined. In addition, since the adjustment value of the present embodiment is information indicating a voltage difference from the design value, the first adjustment value for the first drive signal generation unit 70A and the second adjustment for the second drive signal generation unit 70B. Values are determined individually. When the first drive signal generation unit 70A and the second drive signal generation unit 70B have designed characteristics, an adjustment value indicating that adjustment is not required is determined. The adjustment value determined in this step is determined based on the voltage of the adjustment signal AS that is not applied to the piezo element 417. For this reason, the obtained adjustment value accurately reflects the characteristics of the drive signal generation units 70A and 70B.

  In the step of writing the adjustment value (S140), the calculated adjustment value is written into the printer 1. In this step, the CPU 204 of the adjustment value setting device 200 first outputs a control command to the printer 1 to change the state of the printer 1. As a result, the printer 1 changes the state in which information can be written to the memory 63 of the printer-side controller 60. If the status of the printer 1 is changed, the CPU 204 of the adjustment value setting device 200 transmits the adjustment values (first adjustment value and second adjustment value) calculated in step S130, and the memory 63 ( Write to the adjustment value storage area 63c). If the adjustment value has been written, the CPU 204 of the adjustment value setting device 200 ends a series of processes relating to the adjustment value setting.

<About actual printing of images>
In this way, the adjustment value stored in the adjustment value storage area 63c of the memory 63 is used in the actual printing after shipment. Here, FIG. 18 is a diagram for explaining adjustment of the drive signal COM in actual printing. FIG. 19 is a diagram showing the size of dots during actual printing.

  In the example illustrated in FIG. 18, the first drive signal generation unit 70A outputs the first drive signal COM_A as designed, and the second drive signal generation unit 70B outputs the second drive signal COM_B having a voltage higher than the design value. Shows when to do. As a result, in this example, in a state where adjustment is not performed, the drive pulse PS3 generated by the second drive signal generation unit 70B is larger than the drive pulses PS1 and PS5 generated by the first drive signal generation unit 70A. Yes. In this case, a negative value is set as the adjustment value.

  Thus, in the main printing after shipment, the DAC value (generation information) is adjusted based on the determined adjustment value (generation information adjustment step), and the drive signal generation units 70A and 70B are adjusted based on the adjusted DAC value. The drive signal COM (first drive signal COM_A, second drive signal COM_B) is generated (drive signal generation step). In this example, for the DAC value for the first drive signal generation unit 70A, the DAC value as the design value is specified based on the first adjustment value indicating that adjustment is not necessary. On the other hand, for the DAC value for the second drive signal generation unit 70B, a DAC value having a value lower than the design value is designated based on the second adjustment value indicating that a voltage higher than the design value is output.

  As a result of the adjustment, the highest voltage VH_A of the first drive signal COM_A and the highest voltage VH_B of the second drive signal COM_B are aligned at the designed voltage value. That is, the generation accuracy of the first drive signal COM_A and the second drive signal COM_B can be improved. As a result, dots can be formed in the shape as designed, and image quality can be improved. For example, taking a large dot as an example, the waveforms of the drive pulses PS1 and PS3 of the first drive signal COM_A and the drive pulse PS5 of the second drive signal COM_B are aligned by adjustment. That is, the drive voltage Vh_A of the drive pulse PS1 and the drive pulse PS3 and the drive voltage Vh_B ′ of the drive pulse PS5 are aligned. Thus, by aligning both drive voltages Vh_A and Vh_B ′, the size of the dots formed using the drive pulse PS1 and the drive pulse PS3 and the size of the dots formed using the drive pulse PS5 Is complete. As a result, as shown in FIG. 19, large dots can be formed in the shape as designed, and image quality can be improved.

  In this embodiment, since the adjustment value is determined based on the adjustment signal AS that is not applied to the piezo element 417, the generation accuracy of the first drive signal COM_A and the second drive signal COM_B can be increased. That is, the variation between the first drive signal generator 70A and the second drive signal generator 70B can be adjusted. Further, the adjustment values are configured for the first drive signal generation unit 70A (first adjustment value) and for the second drive signal generation unit 70B (second adjustment value), and the first drive signal generation Since the characteristics of the unit 70A and the characteristics of the second drive signal generation unit 70B are matched with the design characteristics, the generation accuracy of the drive signal COM by the first drive signal generation unit 70A and the second drive signal generation unit 70B is increased. Can be increased.

  In the present embodiment, the adjustment signal AS is measured by the adjustment value setting device 200 as the adjustment signal measurement device. For this reason, a configuration necessary for measurement can be provided in the adjustment value setting device 200, and need not be provided in the printer 1. Therefore, the configuration of the printer 1 to be measured can be simplified.

=== Second Embodiment ===
Incidentally, in the first embodiment described above, the adjustment signal AS is generated by the digital / analog converter 711A of the first drive signal generation unit 70A and the digital / analog converter 711B of the second drive signal generation unit 70B. However, it is not limited to this configuration. For example, the adjustment signal AS may be generated by the voltage amplification circuits 712A and 712B and the current amplification circuits 72A and 72B as signal amplification units. Hereinafter, the second embodiment configured as above will be described. Here, FIG. 20 is a block diagram illustrating the configuration of the second embodiment.

  As shown in FIG. 20, in this embodiment, a measurement terminal 722A is provided at the output of the first current amplification circuit 72A, and a measurement terminal 722B is provided at the output of the second current amplification circuit 72B. The adjustment signal AS is measured using these measurement terminals 722A and 722B. The configuration of the second embodiment is the same as that of the first embodiment described above except that the arrangement of the measurement terminals 722A and 722B is different and the input voltage of the analog-digital converter is different. For this reason, description will be made with reference to the configuration of the first embodiment as appropriate.

  First, adjustment value setting will be described. The adjustment value setting method is also the same as in the first embodiment described above. Briefly, the adjustment value setting device 200 includes a DAC value (first generation information) for the digital / analog converter 711A of the first drive signal generation unit 70A and a digital / analog converter of the second drive signal generation unit 70B. A DAC value (second generation information) for 711B is output. Thereby, the digital-analog converter 711A of the first drive signal generation unit 70A and the digital-analog converter 711B of the second drive signal generation unit 70B generate a pre-amplification adjustment signal. Then, for each pre-amplification adjustment signal, the voltage is amplified by each of the voltage amplification circuit 712A of the first drive signal generation unit 70A and the voltage amplification circuit 712B of the second drive signal generation unit 70B, and the first current amplification circuit 72A Each of the second current amplifier circuits 72B amplifies the current. The adjustment signal AS in the present embodiment is obtained by the amplification of the voltage and current. That is, the first adjustment signal AS_A ′ is output from the first current amplification circuit 72A, and the second adjustment signal AS_B ′ is output from the second current amplification circuit 72B.

  Next, the voltages of the first adjustment signal AS_A and the second adjustment signal AS_B are input to the adjustment value setting device 200. Here, the measurement probe 211 is brought into contact with the measurement terminal 722A on the first current amplification circuit 72A side and the voltage of the first adjustment signal AS_A ′ is input, and the measurement probe 211 is connected to the second current amplification circuit 72B side. The voltage of the second adjustment signal AS_B ′ is input in contact with the measurement terminal 722B. The input voltage of the first adjustment signal AS_A ′ and the voltage of the second adjustment signal AS_B ′ are converted into digital values by the analog-digital conversion unit 203 and output to the CPU 204 of the adjustment value setting device 200. The CPU 204 recognizes the voltage of the first adjustment signal AS_A ′ and the voltage of the second adjustment signal AS_B ′ based on the digital value from the analog-digital conversion unit 203. Then, the CPU 204 obtains an adjustment value (first adjustment value, second adjustment value) based on the recognized voltage of the first adjustment signal AS_A ′ and the voltage of the second adjustment signal AS_B ′, and finds the obtained adjustment value. Are stored in the adjustment value storage area 63c of the printer-side controller 60.

  Also in the second embodiment, the drive signal COM (first drive signal COM_A, second drive signal COM_B) is adjusted based on the adjustment value during the actual printing of the image. The variation of the two drive signal generation units 70B is prevented, and the drive signal COM can be generated with high accuracy. Also, the first adjustment signal AS_A ′ and the second adjustment signal AS_B ′ of the present embodiment are signals amplified by the voltage amplification circuits 712A and 712B and the current amplification circuits 72A and 72B. For this reason, the adjustment signal AS is a signal close to the drive signal COM that is actually output. Therefore, the voltage of the adjustment signal AS can be measured with high accuracy, and the generation accuracy of the drive signal COM can be further increased.

=== Third Embodiment ===
Incidentally, in both the first embodiment and the second embodiment described above, the adjustment signal AS is measured and the adjustment value is set using the adjustment value setting device 200. In this regard, the adjustment signal AS may be measured and the adjustment value set by the printer-side controller 60 of the printer 1. Hereinafter, the third embodiment configured as described above will be described. Here, FIG. 21 is a block diagram illustrating the configuration of the third embodiment. FIG. 22 is a flowchart for explaining the adjustment operation of the drive signal COM performed in association with the printing operation.

  As shown in FIG. 21, in the third embodiment, the difference from the first embodiment described above is that the first analog-digital converter 65A and the second analog-digital converter 65B are provided in the printer-side controller 60. It is in the point. Then, the first analog-to-digital converter 65A digitally converts the output voltage of the digital-to-analog converter 711A included in the first drive signal generation unit 70A, and outputs the converted output voltage (digital value) to the CPU 62. The second analog-digital converter 65B digitally converts the output voltage of the digital-analog converter 711B included in the second drive signal generation unit 70B, and outputs the converted output voltage to the CPU 62. Further, an adjustment value setting program is stored in the memory 63 in order to cause the printer-side controller 60 to perform adjustment value setting and the like. This adjustment value setting program is a kind of computer program, and has a code for executing adjustment value setting processing.

  Next, the adjustment value setting process performed in the third embodiment will be described. This adjustment value setting process is performed by the printer-side controller 60 (CPU 62) every time a print command is output from the computer 110 (for each print job), for example. For this reason, the process is started upon receipt of a print command from the computer (S210). When receiving the print command, the CPU 62 outputs the first adjustment signal AS_A (S220). That is, the CPU 62 outputs the DAC value as the first generation information to the digital-analog converter 711A of the first drive signal generation unit 70A. This DAC value corresponds to the maximum voltage VH of the drive pulse PS, for example, as in the first embodiment described above. As a result, the digital-analog converter outputs the first adjustment signal AS_A. The output first adjustment signal AS_A is digitally converted by the first analog-digital converter 65A and output to the CPU 62. Then, the CPU 62 measures the output voltage of the first adjustment signal AS_A (S230). This output voltage measurement is performed on the converted digital data. Then, an average value of a plurality of acquired digital data is set as a measured value of the output voltage of the first adjustment signal AS_A. In this embodiment, the average value of the digital data acquired five times is used as the measurement value. The obtained measurement value is temporarily stored in the work area of the memory 63, for example.

  If the output voltage of the first adjustment signal AS_A is measured, the second adjustment signal AS_B is output (S240). The second adjustment signal AS_B is also output in the same manner as the first adjustment signal AS_A. That is, the CPU 62 outputs a DAC value (second generation information) corresponding to the highest voltage VH of the drive pulse PS to the digital-analog converter 711B of the second drive signal generation unit 70B. As a result, the second adjustment signal AS_B is output from the digital-analog converter. The second adjustment signal AS_B is digitally converted by the second analog-digital converter 65B. Next, the CPU 62 measures the output voltage of the second adjustment signal AS_B (S250). The output voltage is also measured in the same manner as the first adjustment signal AS_A. In this embodiment, the average value of the digital data acquired five times is used as the measurement value. Then, the measured value is temporarily stored in the work area of the memory 63, for example.

  If the output voltages of the first adjustment signal AS_A and the second adjustment signal AS_B are measured, the measured values are compared (S260). In other words, the difference in characteristics between the first drive signal generator 70A and the second drive signal generator 70B is recognized. Here, if the difference between the measured values is within the allowable range, the CPU 62 determines that the characteristics of the first drive signal generation unit 70A and the characteristics of the second drive signal generation unit 70B are the same, and the drive signal COM No adjustment is made. On the other hand, if the difference between the measured values exceeds the allowable range, the CPU 62 sets an adjustment value (S270). The setting of the adjustment value is performed in the same manner as in the first embodiment described above based on the difference between the measurement values (that is, the difference between the first adjustment signal AS_A and the second adjustment signal AS_B). The set adjustment value is stored in the work area of the memory 63, for example.

  When the necessary adjustment value is set in this way, the CPU 62 controls the printing operation (S280). As described with reference to FIG. 13, the printing operation includes a paper feeding operation (S20), a dot forming operation (S30), a conveying operation (S40), a paper discharge determination (S50), a paper discharge process (S60), and printing. Completion of determination (S70). In addition, since the content of each process is the same, description is abbreviate | omitted. In this printing operation, the DAC value is adjusted based on the adjustment value, and the first drive signal COM_A and the second drive signal COM_B are adjusted using the adjusted DAC value. For this reason, the generation accuracy of the first drive signal COM_A and the second drive signal COM_B can be increased, and as a result, the quality of the printed image can be increased.

  In addition, in this embodiment, the adjustment is performed by the printer-side controller 60 that outputs the DAC value. Therefore, the adjustment can be performed even after the printer 1 is shipped. It is also possible to cope with changes in the state of the printer 1 over time. Furthermore, since the adjustment is performed in response to the reception of the print command, the image can be printed with the optimized drive signal COM.

  In the third embodiment, after confirming that the first adjustment signal AS_A and the second adjustment signal AS_B are aligned, the printing operation (S280) may be performed. Hereinafter, a modified example configured as described above will be described. Here, FIG. 23 is a flowchart for explaining the operation in this modification. Specifically, it is a flowchart for explaining details of an adjustment value setting process (corresponding to S270 in FIG. 22). The processes other than the adjustment value setting are the same as those in the third embodiment described above.

  In the setting process of the modified example, the first adjustment signal AS_A is used as a reference, and the output voltage of the second adjustment signal AS_B is set to the output voltage of the first adjustment signal AS_A. For this reason, the CPU 62 sets a temporary second adjustment value used for the second adjustment signal AS_B based on the difference between the measurement values (S271). Next, a second adjustment signal AS_B (temporary second adjustment signal) based on the temporary second adjustment value is generated. That is, the provisional second adjustment value is output to the analog / digital converter of the second drive signal generation unit 70B. If the second adjustment signal AS_B based on the provisional second adjustment value is generated, the output voltage of the second adjustment signal AS_B is measured to obtain the measurement value (S273). Also in this measurement, an average value of a plurality of times is acquired. In this modification, an average value of 5 times is acquired as a measurement value. If the measurement value is acquired, the acquired measurement value (measurement value of the second adjustment signal AS_B) is compared with the measurement value of the first drive signal COM_A, and it is determined whether the difference is within an allowable range (S274). ). Here, if it is within the allowable range, the provisional second adjustment value at that time is set as the second adjustment value, and the adjustment value setting process is ended. Then, the printing operation (S280) is executed. On the other hand, if it exceeds the allowable range, the process returns to step S271 and the series of processes is repeatedly executed.

  In such a modification, after confirming that the characteristics of the first drive signal generator 70A and the characteristics of the second drive signal generator 70B are aligned, the printing operation (S280) is performed. For this reason, the characteristics of the drive signal generation units 70A and 70B can be reliably aligned.

=== Other Embodiments ===
Each of the above-described embodiments is mainly described with respect to the printing system 100 having the printer 1, which includes disclosure of a unit signal (drive pulse) adjustment method, 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.

<Selection of Adjustment Signal AS>
In the third embodiment, the first adjustment signal AS_A is digitally converted by the first analog-digital converter 65A, and the second adjustment signal AS_B is digitally converted by the second analog-digital converter 65B. In this regard, the first adjustment signal AS_A and the second adjustment signal AS_B may be sequentially measured by switching the changeover switch. Here, FIG. 24 is a diagram illustrating an embodiment in which the printer-side controller 60 is provided with a changeover switch.

  In this embodiment, a multiplexer 66 is provided as a changeover switch. The multiplexer 66 receives the output of the digital / analog converter 711A of the first drive signal generator 70A, the output of the digital / analog converter 711B of the second drive signal generator 70B, and the switching control signal from the CPU 62. ing. The output from the multiplexer 66 is input to the analog / digital converter 65C. The output of the analog / digital converter 65C is input to the CPU 62.

  Each time the switching control signal from the CPU 62 is input, the multiplexer 66 switches the signal output to the analog-digital converter 65C. For this reason, the adjustment signal AS to be measured can be switched and output to the analog-digital converter 65C. That is, the first adjustment signal AS_A and the second adjustment signal AS_B can be switched and output to the analog-to-digital converter 65C. Thereby, the number of analog-digital converters 65C can be reduced, and the number of parts can be reduced. Further, since the measurement can be performed by the same analog-digital converter 65C, the measurement accuracy can be increased.

<Adjustment of drive signal generator>
In the first to third embodiments described above, both the first adjustment signal AS_A and the second adjustment signal AS_B are set to the designed voltage value. However, the present invention is not limited to this method. One adjustment signal may be aligned with the other adjustment signal.

  Further, the DAC value (generation information) for generating the adjustment signal AS is not limited to the maximum voltage VH of the drive pulse PS. For example, it may be an intermediate voltage VC (see FIG. 8A) of the drive pulse PS. This intermediate voltage corresponds to the start voltage of the drive pulse PS. By making the intermediate voltage VC to be adjusted, fluctuations in voltage can be prevented when the drive signal COM applied to the piezo element 417 is switched from one drive signal COM to the other drive signal COM. . For this reason, the switching of the drive signal COM can be performed smoothly.

<Generation information and measurement target>
The generation information is not limited to the DAC value described above. For example, change amount information indicating a voltage change amount for each update period τ may be used. Further, elements other than voltage, for example, current may be measured.

<About drive elements>
In the above-described embodiment, ink is ejected using the piezo element 417. However, the element for ejecting 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 the drive signal COM>
In the above-described embodiment, the printer 1 that outputs two types of drive signals COM including the first drive signal COM_A and the second drive signal COM_B has been described as an example. However, the present invention is not limited to this configuration. That is, even a printer that can generate three or more types of drive signals COM at the same time or a printer that can generate one type of drive signals COM can be adjusted in the same manner.

<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.

<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 ink jet technique is applied such as an apparatus and a DNA chip manufacturing apparatus. These methods and manufacturing methods are also within the scope of application.

1 is a diagram illustrating a configuration of a printing system. FIG. 2A is a block diagram illustrating configurations of a computer and a printer. FIG. 2B is a diagram schematically illustrating a part of the memory included in the printer. FIG. 3A is a diagram illustrating the configuration of the printer. FIG. 3B is a side view illustrating the configuration of the printer. It is a disassembled perspective view of a head unit. It is sectional drawing explaining the structure of a head. FIG. 6 is a block diagram illustrating the configuration of the drive signal generation circuit. FIG. 7A is a block diagram for explaining the configuration of the first waveform generation circuit and the second waveform generation circuit. FIG. 7B is a diagram for explaining the relationship between the DAC value input to the digital-analog converter and the output voltage from the voltage amplification circuit. FIG. 8A is a diagram for explaining a part of the generated drive signal. FIG. 8B is a diagram for explaining an operation of dropping the output voltage of the first current amplifier circuit from the voltage V1 to the voltage V4. It is a figure explaining the structure of a current amplifier circuit. It is a block diagram explaining the structure of a head control part. FIG. 11A is a diagram illustrating a first drive signal, a second drive signal, and necessary control signals. FIG. 11B is a diagram for explaining pixel data, a waveform pattern selection pattern, and selection data. It is a figure explaining the waveform part applied to a piezoelectric element at the time of formation of a small dot, the formation of a medium dot, and the formation of a large dot. It is a flowchart explaining printing operation. FIG. 14A is a diagram illustrating a drive pulse generated by the first drive signal generation unit. FIG. 14B is a diagram illustrating an example of an output voltage in the first drive signal generation unit. FIG. 14C is a diagram illustrating the drive pulse generated by the second drive signal generation unit. FIG. 14D is a diagram illustrating an example of an output voltage in the second drive signal generation unit. FIG. 14E is a diagram for explaining a difference in size of dots formed using the drive pulse of FIG. 14A and the drive pulse of FIG. 14C. It is a block diagram explaining the apparatus used for the setting of an adjustment value. It is a flowchart which shows the flow of an adjustment value setting process. FIG. 17A is a diagram illustrating a first adjustment signal generated by the first drive signal generation unit. FIG. 17B is a diagram illustrating a second adjustment signal generated by the second drive signal generation unit. It is a figure explaining adjustment of the drive signal in this printing. It is a figure which shows the magnitude | size of the dot at the time of this printing. It is a block diagram explaining the structure of 2nd Embodiment. It is a block diagram explaining the structure of 3rd Embodiment. It is a flowchart explaining the adjustment operation of the drive signal performed in relation to the printing operation. It is a flowchart explaining the other example of the setting process of an adjustment value. It is a figure explaining embodiment which provided the changeover switch in the printer side controller.

Explanation of symbols

1 printer, 20 paper transport mechanism, 21 paper feed roller, 22 transport motor,
23 transport roller, 24 platen, 25 paper discharge roller,
30 Carriage moving mechanism, 31 Carriage motor, 32 Guide shaft,
33 Timing belt, 34 Drive pulley, 35 Drive pulley,
40 head units, 41 heads, 41A flow path 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 diaphragm, 416 lid member, 416a supply side communication port, 417 piezo element,
42 needle side case member, 43 head side case member, 44 head control board,
45 head side wiring member, 50 detector group, 51 linear encoder,
52 Rotary encoder, 53 Paper detector, 54 Paper width detector,
55 Thermistor, 60 Printer side controller, 61 Interface section,
62 CPU, 63 memory, 64 control unit,
65A first analog-digital converter, 65B second analog-digital converter,
65C analog-digital converter, 66 multiplexer, 70 drive signal generation circuit,
70A first drive signal generation unit, 71A first waveform generation circuit,
711A digital analog converter, 712A voltage amplification circuit, 713A measurement terminal,
72A first current amplifier circuit, 721A first transistor pair, 722A measurement terminal,
70B second drive signal generation unit, 71B second waveform generation circuit,
711B digital analog converter, 712B voltage amplification circuit, 713B measurement terminal,
72B second current amplification circuit, 721B second transistor pair, 722B measurement terminal,
81A first shift register, 81B second shift register, 82A first latch circuit,
82B second latch circuit, 83 decoder, 84 control logic, 85 prevention circuit,
86A first level shifter, 86B second level shifter,
87A first switch, 87B second switch,
100 printing system, 110 computer, 110A computer,
111 Host side controller, 112 interface unit, 113 CPU,
114 memory, 120 display device, 130 input device, 131 keyboard,
132 mouse, 140 recording / reproducing device, 141 flexible disk drive device,
142 CD-ROM drive device, 200 adjustment value setting device,
201 printer side interface unit, 202 probe side interface unit,
203 analog-digital conversion unit, 204 CPU, 205 memory,
211 Measuring probe, S paper, CTR controller board, HC head controller,
Nz nozzle, Q1 NPN transistor, Q2 PNP transistor,
COM_A first drive signal, COM_B second drive signal, LAT latch signal,
CH_A 1st change signal, CH_B 2nd change signal, PS drive pulse,
Vh drive voltage, Vhs reference drive voltage, VH maximum voltage, Vc reference voltage,
VC intermediate voltage, CTL_A control signal line group, CTL_B control signal line group,
AS adjustment signal,
AS_A, AS_A ′ first adjustment signal,
AS_B, AS_B ′ second adjustment signal,
pVH_A voltage of the first adjustment signal,
pVH_B Voltage of second adjustment signal

Claims (12)

An adjustment signal generation step for generating an adjustment signal that is not applied to the element in a drive signal generation unit that generates a drive signal applied to the element that performs an operation for ejecting ink based on the generation information;
A signal measuring step for measuring the adjustment signal;
A generation information adjustment step of adjusting the generation information based on a measurement result of the adjustment signal;
A drive signal generation step for causing the drive signal generation unit to generate a drive signal based on the generated generation information after adjustment;
A drive signal generation method comprising :
In the adjustment signal generation step,
A first switch provided between the element and a first drive signal generator that generates a first drive signal based on first generation information, and a second switch that generates a second drive signal based on second generation information 2 to turn off both the drive signal generator and the second switch provided between the elements;
Simultaneously causing the first drive signal generator to generate a first adjustment signal and causing the second drive signal generator to generate a second adjustment signal;
In the signal measurement step,
Measuring the first adjustment signal and the second adjustment signal;
In the generation information adjustment step,
Adjusting the first generation information and the second generation information based on the measurement result of the first adjustment signal and the measurement result of the second adjustment signal;
In the drive signal generation step,
Based on the adjusted first generation information, the first drive signal generation unit generates the first drive signal, and based on the adjusted second generation information, the second drive signal generation unit generates the first drive signal. 2. A drive signal generation method for generating a drive signal. The drive signal generation method according to claim 1 ,
In the adjustment signal generation step,
Generating the pre-amplification drive signal before amplification based on the generation information, causing the pre-amplification drive signal generation unit of the drive signal generation unit to generate the adjustment signal;
In the signal measurement step,
A drive signal generation method for measuring the adjustment signal generated by the pre-amplification drive signal generation unit. The drive signal generation method according to claim 1 ,
In the adjustment signal generation step,
Amplifying the drive signal before amplification generated based on the generation information, causing the signal amplification unit of the drive signal generation unit to generate the adjustment signal,
In the signal measurement step,
A drive signal generation method for measuring the adjustment signal generated by the signal amplification unit. A drive signal generation method according to any one of claims 1 to 3 ,
In the signal measurement step,
A drive signal generation method for measuring a voltage of the adjustment signal. A drive signal generation method according to any one of claims 1 to 4 ,
In the signal measurement step,
A drive signal generation method for measuring the adjustment signal with an adjustment signal measurement device. A drive signal generation method according to any one of claims 1 to 4 ,
In the signal measurement step,
A drive signal generation method in which the adjustment signal is measured by a controller that outputs the generation information. A drive signal generation method according to any one of claims 1 to 4 ,
In the signal measurement step,
A first adjustment signal generated by the first drive signal generation unit and a second adjustment signal generated by the second drive signal generation unit are sequentially selected via a changeover switch, and the first generation information is selected. And a drive signal generation method that is measured by a controller that outputs the second generation information. A drive signal generation method according to any one of claims 1 to 7 ,
In the adjustment signal generation step,
A drive signal generation method for generating the adjustment signal based on generation information corresponding to a maximum voltage in a unit signal for defining from start to end of operation of the element. A drive signal generation method according to any one of claims 1 to 7 ,
In the adjustment signal generation step,
A drive signal generation method for generating the adjustment signal based on generation information corresponding to a start voltage in a unit signal for defining from start to end of operation of the element. (A) A first drive signal generation unit that generates a first drive signal applied to an element that performs an operation for ejecting ink based on the first generation information, before amplification based on the first generation information The highest voltage or start voltage in the unit signal for defining from the start to the end of the operation of the element to the pre-amplification drive signal generation unit for generating the pre-amplification drive signal or the signal amplification unit for amplifying the pre-amplification drive signal Generating a first adjustment signal not applied to the element based on the generation information corresponding to
A pre-amplification drive signal for generating a pre-amplification drive signal based on the second generation information, based on the second generation information, of a second drive signal generation unit that generates a second drive signal applied to the element based on second generation information. Based on the generation information corresponding to the highest voltage or the start voltage in the unit signal for defining from the start to the end of the operation of the element to the generation unit or the signal amplification unit that amplifies the drive signal before amplification, the element An adjustment signal generation step of generating a second adjustment signal that is not applied;
(B) The pre-amplification drive signal generation unit of the first drive signal generation unit or the voltage of the first adjustment signal generated by the signal amplification unit and the pre-amplification drive of the second drive signal generation unit The voltage of the second adjustment signal generated by the signal generation unit or the signal amplification unit is measured by an adjustment signal measurement device, or sequentially selected via a changeover switch, and the generation information is selected. A signal measurement step to measure with the controller to output,
(C) a generation information adjustment step of adjusting first generation information based on the measurement result of the first adjustment signal and adjusting second generation information based on the measurement result of the second adjustment signal;
(D) Based on the adjusted first generation information, the first drive signal generation unit generates the first adjustment signal, and based on the adjusted second generation information, the second drive signal A drive signal generation step of causing the generation unit to generate the second adjustment signal;
A drive signal generation method comprising: (A) an element that performs an operation for ejecting ink;
(B) a drive signal generation unit that generates a drive signal applied to the element based on generation information;
(C) causing the drive signal generator to generate an adjustment signal that is not applied to the element;
Adjusting the generation information based on the generated adjustment signal;
Based on the adjusted generation information, a controller that causes the drive signal generation unit to generate a drive signal;
A printing device comprising:
The controller is
A first switch provided between the element and a first drive signal generator that generates a first drive signal based on first generation information, and a second switch that generates a second drive signal based on second generation information 2 to turn off both the drive signal generator and the second switch provided between the elements;
Simultaneously causing the first drive signal generator to generate a first adjustment signal and causing the second drive signal generator to generate a second adjustment signal;
Measuring the first adjustment signal and the second adjustment signal;
Adjusting the first generation information and the second generation information based on the measurement result of the first adjustment signal and the measurement result of the second adjustment signal;
Based on the adjusted first generation information, the first drive signal generation unit generates the first drive signal, and based on the adjusted second generation information, the second drive signal generation unit generates the first drive signal. A printing apparatus that generates two drive signals. A printing system having a printing device and a printing control device for controlling the printing device,
The printing apparatus includes:
(A) an element that performs an operation for ejecting ink;
(B) a drive signal generation unit that generates a drive signal applied to the element based on generation information;
(C) causing the drive signal generator to generate an adjustment signal that is not applied to the element;
Adjusting the generation information based on the generated adjustment signal;
Based on the adjusted generation information, a controller that causes the drive signal generation unit to generate a drive signal;
A printing system comprising:
The controller is
A first switch provided between the element and a first drive signal generator that generates a first drive signal based on first generation information, and a second switch that generates a second drive signal based on second generation information 2 to turn off both the drive signal generator and the second switch provided between the elements;
Simultaneously causing the first drive signal generator to generate a first adjustment signal and causing the second drive signal generator to generate a second adjustment signal;
Measuring the first adjustment signal and the second adjustment signal;
Adjusting the first generation information and the second generation information based on the measurement result of the first adjustment signal and the measurement result of the second adjustment signal;
Based on the adjusted first generation information, the first drive signal generation unit generates the first drive signal, and based on the adjusted second generation information, the second drive signal generation unit generates the first drive signal. A printing system that generates two drive signals.

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