JP2007130938A - Liquid ejector, liquid ejection method, and program for liquid ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the trouble associated with the case when an unscheduled drive signal is selected wrong. <P>SOLUTION: The liquid ejector has (A) an element which performs the ejection action for making a liquid ejected, and (B) a drive signal generating part which generates a drive signal with a driving pulse formed in a certain period of time for making the element perform the ejection action, and another drive signal with both another driving pulse formed in the other period of time for making the element perform the ejection action, and a dummy pulse formed in the certain period of time for making the element perform the ejection action when the dummy pulse is selected wrong in place of the driving pulse. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid ejection apparatus, a liquid ejection method, and a program for the liquid ejection apparatus.

There are various types of liquid ejecting apparatuses that eject liquid onto an object, such as a printing apparatus, a color filter manufacturing apparatus, and a staining apparatus. In this liquid ejection apparatus, a plurality of types of drive signals having drive pulses are generated, and a drive pulse for ejecting liquid is selectively applied to an element (for example, a piezo element) that operates to eject liquid. Thus, there is one that discharges liquid (for example, see Patent Document 1). In this liquid ejection apparatus, a plurality of types of drive pulses are allocated to the respective drive signals.
JP 2000-52570 A

  By the way, the generation period and the number of drive pulses included in each drive signal are determined according to the device and application. For this reason, in a certain period, a drive pulse may be generated with one drive signal, and a signal with a constant potential may be generated with another drive signal.

  In this type of device, a different drive signal may be selected by mistake due to noise generated inside the device or noise from outside the device. If another drive signal is selected by mistake during a certain period as described above, a drive pulse is not applied to the element, and a signal having a constant potential is applied to the element. As a result, there is a problem that the liquid is not discharged.

  The present invention has been made in view of such circumstances, and an object of the present invention is to prevent problems associated therewith when an unplanned drive signal is selected by mistake.

The main invention for achieving the object is as follows:
(A) an element that performs a discharge operation for discharging liquid;
(B) a drive signal having a drive pulse generated in a certain period and causing the element to perform the ejection operation;
Another drive pulse generated in another period that causes the element to perform the ejection operation, and a dummy pulse generated in the certain period that is erroneously replaced with the drive pulse Other drive signals having dummy pulses that cause the element to perform the ejection operation, and
A drive signal generator for generating
(C).

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

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

That is, (A) an element that performs an ejection operation for ejecting liquid, and (B) a drive signal that includes a drive pulse that is generated in a certain period and that causes the element to perform the ejection operation; Another drive pulse generated in another period that causes the element to perform the ejection operation, and a dummy pulse generated in the certain period that is erroneously replaced with the drive pulse The liquid ejection device having (C) a drive signal generation unit that generates another drive signal having a dummy pulse that causes the element to perform the ejection operation.
According to such a liquid ejecting apparatus, even if another drive signal is selected by mistake during a certain period, the dummy pulse is applied to the element that performs the ejecting operation. Since the element performs an ejection operation using a dummy pulse, it is possible to prevent a problem that no liquid is ejected.

In this liquid ejection apparatus, the drive pulse and the other drive pulse are applied to the element by applying the necessary part of the drive signal selected based on selection information and the necessary part of the other drive signal to the element. It is preferable to have a drive pulse application unit that applies to the element.
According to such a liquid ejecting apparatus, the drive pulse application unit selects the necessary part of the drive signal and the necessary part of the other drive signal based on the selection information. It can be carried out.

In this liquid ejection apparatus, the drive pulse application unit includes a switch that controls application of the drive signal to the element and another switch that controls application of the other drive signal to the element. Preferably, the switch and the other switch are controlled based on the selection information, and the necessary part of the drive signal and the necessary part of the other drive signal are applied to the element.
According to such a liquid ejecting apparatus, by controlling the switch and other switches, the necessary part of the drive signal and the necessary part of the other drive signal are applied to the element. Is easy.

In this liquid ejection apparatus, it is preferable that the dummy pulse is for ejecting the same amount of liquid as the drive pulse.
According to such a liquid ejecting apparatus, it is possible to replace the liquid ejected by the drive pulse with the liquid ejected by the dummy pulse.

In this liquid ejection apparatus, it is preferable that the dummy pulse has a waveform having the same shape as the drive pulse.
According to such a liquid ejecting apparatus, even if another drive signal is selected while a drive pulse is being applied to the element, a sudden change in the potential applied to the element can be prevented.

In this liquid ejection apparatus, when the drive signal is another dummy pulse generated in the other period and is selected in error instead of the other drive pulse, the ejection operation is performed on the element. It is preferable to have other dummy pulses to be performed.
According to such a liquid ejecting apparatus, even if a drive signal is erroneously selected in another period, another dummy pulse is applied to the element. And since the discharge operation by another dummy pulse is performed, the malfunction that a liquid is not discharged can be prevented also in another period.

In this liquid ejection apparatus, it is preferable that the other dummy pulse is for ejecting the same amount of liquid as the other driving pulse.
According to such a liquid ejecting apparatus, the liquid ejected by another dummy pulse can be replaced by the liquid ejected by another dummy pulse.

In this liquid ejection apparatus, it is preferable that the other dummy pulse has a waveform having the same shape as the other driving pulse.
According to such a liquid ejecting apparatus, even if a drive signal is selected while another drive pulse is being applied to the element, it is possible to prevent a sudden change in the potential applied to the element.

In such a liquid discharge apparatus, the element is preferably a piezo element.
According to such a liquid ejecting apparatus, it is possible to obtain sufficient force and high responsiveness for ejecting liquid.

In this liquid ejecting apparatus, it is preferable that the liquid is a liquid ink for printing.
According to such a liquid ejecting apparatus, it is possible to prevent missing dots during printing.

It will also be clarified that the following liquid ejection apparatus can be realized.
That is,
(A) an element configured by a piezo element and performing a discharge operation for discharging a liquid;
(B) a drive signal having a drive pulse generated in a certain period and causing the element to perform the ejection operation; and another drive pulse generated in another period and applied to the element. Another drive pulse for performing the discharge operation, and a dummy pulse generated in the certain period for discharging the same amount of liquid as the drive pulse, and the same as the drive pulse A drive signal generator that generates a waveform of a shape and generates another drive signal having a dummy pulse that causes the element to perform the ejection operation when it is erroneously selected instead of the drive pulse;
(C) a switch that controls application of the drive signal to the element, and another switch that controls application of the other drive signal to the element, and the switch and others based on the selection information A drive pulse for applying the drive pulse and the other drive pulse to the element by applying a necessary part of the drive signal and a necessary part of another drive signal selected by controlling the switches of the drive to the element. An application unit,
(D) The drive signal is another dummy pulse generated in the other period, for discharging the same amount of liquid as the other drive pulse, and the other drive pulse. If the waveform is of the same shape as, and selected in error instead of the other drive pulse, it has another dummy pulse that causes the element to perform the ejection operation,
(E) The liquid is a liquid ink for printing.
(F) A liquid ejection device can be realized.
According to such a liquid ejecting apparatus, since almost all the effects described above can be achieved, the object of the present invention can be achieved most effectively.

It is also clarified that the following liquid discharge method can be realized.
In other words, (a) a drive signal generated in a certain period and having a drive pulse for causing the element that performs the discharge operation to discharge the liquid to perform the discharge operation, and generated in another period Other drive pulses that cause the element to perform the ejection operation, and dummy pulses that are generated in the certain period and are selected in error instead of the drive pulse, Generating another drive signal having a dummy pulse that causes the device to perform the ejection operation; and (b) selectively applying the drive pulse and the other drive pulse to the device based on selection information. And a step of performing a liquid ejection method.

It is also clarified that the program for the next liquid ejection apparatus can be realized.
That is, a program for a liquid ejection apparatus having an element that performs ejection operation for ejecting liquid, a drive signal generation unit, and a drive pulse application unit, and (a) the drive signal generation unit has a certain period of time. A drive signal having a drive pulse that is generated in step (1) and causing the element to perform the ejection operation, and another drive pulse that is generated in another period and that causes the element to perform the ejection operation. Drive pulses, and other drive signals having dummy pulses that cause the element to perform the ejection operation when selected in error instead of the drive pulses. And (b) causing the drive pulse application unit to selectively apply the drive pulse and the other drive pulse to the element based on selection information. That the program can be implemented to perform the step to I, a.

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

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

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

  The print data is data in a format that can be interpreted by the printer 1, and includes various command data and dot formation data SI (see FIG. 7). The command data is data for instructing the printer 1 to execute a specific operation. The command data includes, for example, command data for instructing paper feed, command data for indicating the carry amount, and command data for instructing paper discharge. The dot formation data SI is data relating to dots formed on the paper S (data such as dot color and size) and is determined for each unit area. Here, the unit area refers to a rectangular area virtually defined on a medium such as the paper S, and the size and shape are determined according to the print resolution. The dot formation data SI in this embodiment is composed of gradation data indicating the size of dots. The size of the dot is determined by the amount of ink (liquid) ejected. For this reason, the dot formation data SI corresponds to ejection amount information indicating the amount of ink (liquid) to be ejected. This gradation data is composed of 2-bit data. Accordingly, the dot formation data SI includes data [00] corresponding to no dot (no ink ejection), data [01] corresponding to the formation of small dots, and data [10] corresponding to the formation of medium dots. And data [11] corresponding to the formation of large dots. That is, the printer 1 can form an image with four gradations for one unit area.

=== Printer 1 ===
<About the configuration of the printer 1>
Next, the configuration of the printer 1 will be described. Here, FIG. 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. 2 is also referred to.

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

<Regarding the paper transport mechanism 20>
The paper transport mechanism 20 corresponds to a medium transport unit that transports a medium. The paper transport mechanism 20 feeds the paper S as a medium to a printable position, or transports the paper S by a predetermined transport amount in the transport direction. This transport direction is a direction that intersects the carriage movement direction described below. 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 printer-side controller 60. 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. Here, since the head unit 40 has the head 41, the carriage movement direction corresponds to the head movement direction in which the head 41 moves. The carriage moving mechanism 30 corresponds to a head moving unit that moves the head 41 in a predetermined direction. The head 41 has a nozzle. For this reason, the head movement direction can also be referred to as the nozzle movement direction. The carriage moving mechanism 30 can be referred to as a nozzle moving unit.

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

<About the head unit 40>
The head unit 40 is for ejecting ink toward the paper S. The head unit 40 is attached to the carriage CR. The head 41 included in the head unit 40 is provided on the lower surface of the head case 42. The head control unit HC included in the head unit 40 is provided inside the head case 42. The head controller HC will be described later.

  The structure of the head 41 will be described. Here, FIG. 4 is a cross-sectional view for explaining the structure of the head 41. FIG. 5 is a diagram for explaining the arrangement of the nozzles Nz included in the head 41. 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.

  As shown in FIG. 5, in the head 41, the nozzles Nz are arranged in the transport direction of the paper S at a predetermined pitch to constitute a nozzle row. In the present embodiment, this nozzle row corresponds to a nozzle group including a plurality of nozzles Nz. The transport direction of the paper S corresponds to another predetermined direction that intersects the predetermined direction. A plurality of nozzle rows are provided at different positions in the carriage movement direction as a predetermined direction. The piezo element 417 is provided corresponding to each nozzle Nz and functions as an element that performs an ejection operation for ejecting ink.

  The head 41 can determine the type of ink to be ejected for each nozzle row. That is, the type of liquid to be ejected can be determined for each nozzle group. In the illustrated head 41, in order from the left side of FIG. 5, a first nozzle row Nk that discharges black ink, a second nozzle row Ny that discharges yellow ink, and a third nozzle row Nc that discharges cyan ink, A fourth nozzle row Nm for ejecting magenta ink is provided.

  In the printer 1, as described above, there is no dot corresponding to the data [00] of the dot formation data SI, the formation of small dots corresponding to the data [01], the formation of medium dots corresponding to the data [10], and Four types of control of forming large dots corresponding to data [11] can be performed. For this reason, it is possible to eject a plurality of types of inks having different amounts from each nozzle Nz according to the dot formation data SI (ejection amount information). For example, from each nozzle Nz, an amount of ink that can form a large dot (large ink droplet), an amount of ink that can form a medium dot (medium ink droplet), and an amount of ink that can form a small dot (small ink) Ink droplets) 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 and 3B, the detector group 50 includes a linear encoder 51, a rotary encoder 52, a paper detector 53, a paper width detector 54, and the like. The linear encoder 51 is for detecting the position of the carriage CR (head 41, nozzle Nz) in the carriage movement direction. The rotary encoder 52 is for detecting the rotation amount of the transport roller 23. The paper detector 53 is for detecting the leading end position of the paper S to be printed. The paper width detector 54 is for detecting the width of the paper S to be printed.

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

  Further, the CPU 62 outputs a head control signal for controlling the operation of the head 41 to the head control unit HC, or outputs a drive signal COM (first drive signal COM_A, second drive signal COM_B, see FIG. 11). A control signal for generation is output to the drive signal generation circuit 70. For example, as shown in FIG. 7, the head control signals are a clock CLK, dot formation data SI, a latch signal LAT, a first change signal CH_A, and a second change signal CH_B. The latch signal LAT has a latch pulse, and the first change signal CH_A and the second change signal CH_B have a change pulse. These latch pulse and change pulse correspond to timing pulses for defining the timing at which the drive signal COM is applied to the piezo element 417. By using such a head control signal, the printer-side controller 60 uses the drive signal COM, specifically, the drive pulses (first drive pulse PS1 to fifth drive pulse PS5, fine vibration pulse VP, included in the drive signal COM). 11) can be selectively applied to the piezo element 417. For this reason, the printer-side controller 60 corresponds to a controller that applies drive pulses (ejection pulses for ejecting ink) to the piezo elements 417.

  The control signal for generating the drive signal COM is, for example, a DAC value. The DAC value is information for determining the voltage of the signal output from the first drive signal generation unit 70A and the second drive signal generation unit 70B (see FIG. 6A) of the drive signal generation circuit 70, and is extremely short. Updated every update cycle. The waveforms of the first drive signal COM_A and the second drive signal COM_B are determined by this DAC value. For this reason, the DAC value corresponds to waveform generation information.

<About the drive signal generation circuit 70>
FIG. 6A is a block diagram for explaining the configuration of the drive signal generation circuit 70. FIG. 6B is a diagram for explaining the configuration of the first waveform generation circuit 71A and the second waveform generation circuit 71B that the drive signal generation circuit 70 has. FIG. 6C is a diagram for describing the configuration of the first current amplification circuit 72A and the second current amplification circuit 72B. In FIG. 6B and FIG. 6C, the configuration on the second drive signal generation unit 70B side is indicated by reference numerals with parentheses.

  The drive signal generation circuit 70 generates a drive signal COM that is commonly used for each piezo element 417, and corresponds to a drive signal generation unit. The drive signal COM generated by the drive signal generation circuit 70 is commonly used for a plurality of nozzle rows. The drive signal generation circuit 70 simultaneously generates a plurality of types of drive signals COM. That is, the drive signal COM used for all the piezo elements 417 is generated by one drive signal generation circuit 70. The drive signal generation circuit 70 of the present embodiment includes a first drive signal generation unit 70A that generates a first drive signal COM_A and a second drive signal generation unit 70B that generates a second drive signal COM_B. Hereinafter, the first drive signal generation unit 70A and the second drive signal generation unit 70B will be described.

<Regarding First Drive Signal Generation Unit 70A>
The first drive signal generation unit 70A generates a voltage signal corresponding to the DAC value (waveform generation information) 71A, and amplifies the current of the signal generated by the first waveform generation circuit 71A. One current amplifying circuit 72A is provided. The second drive signal generation unit 70B includes a second waveform generation circuit 71B and a second current amplification circuit 72B. The first waveform generation circuit 71A and the second waveform generation circuit 71B have the same configuration, and the first current amplification circuit 72A and the second current amplification circuit 72B have the same configuration. For this reason, the following description is mainly given to the first drive signal generation unit 70A, that is, the first waveform generation circuit 71A and the first current amplification circuit 72A.

  As shown in FIG. 6B, the first waveform generation circuit 71A includes a digital-analog converter 711A (D / A converter) and a voltage amplification circuit 712A. The digital-analog converter 711A is an electric circuit that outputs a voltage signal corresponding to the 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, and is read from the memory 63 and output by the CPU 62. In this embodiment, the DAC value is composed of 10-bit data.

  The voltage amplification circuit 712A amplifies the output voltage from the digital-analog converter 711A to a voltage suitable for the operation of the piezo element 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_Tr1 and the control signal S_Tr2. These control signal S_Tr1 and control signal S_Tr2 are drive signals before current amplification and correspond to signals having a desired waveform. Therefore, the first waveform generation circuit 71A corresponds to a waveform generation circuit that generates a signal having a desired waveform. The control signal S_Tr1 and the control signal S_Tr2 have the same waveform.

  Next, the first current amplifier circuit 72A will be described. The first current amplifier circuit 72A is a circuit for supplying a sufficient current so that the plurality of piezo elements 417 can operate without trouble. 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 two transistors connected in a complementary manner. Specifically, it is composed of an NPN transistor Tr1 and a PNP transistor Tr2 whose emitter terminals are connected to each other. The NPN transistor Tr1 is a transistor that operates when the voltage of the drive signal COM rises. The NPN transistor Tr1 has a collector connected to the power supply and an emitter connected to the output signal line of the first drive signal COM_A. The PNP transistor Tr2 is a transistor that operates when the voltage of the drive signal COM drops. The PNP transistor Tr2 has a collector connected to the ground and an emitter connected to the output signal line of the first drive signal COM_A. The operation of the first current amplification circuit 72A, that is, the first transistor pair 721A is controlled by signals (control signal S_Tr1, control signal S_Tr2) output from the first waveform generation circuit 71A.

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

<About Outline of Generated Drive Signal COM>
Here, an outline of the first drive signal COM_A (corresponding to a drive signal) and the second drive signal COM_B (corresponding to other drive signals) generated by the drive signal generation circuit 70 will be described. In this description, reference is made to FIG.

  The first drive signal COM_A is generated in the first waveform section SS11 generated in the period T1, the second waveform section SS12 generated in the period T2, the third waveform section SS13 generated in the period T3, and the period T4. And a fourth waveform section SS14. Each waveform section SS11 to SS14 has a pulse for causing the piezo element 417 to perform a predetermined operation. That is, the first waveform section SS11 has a first drive pulse PS1, and the second waveform section SS12 has a micro vibration pulse VP. The third waveform section SS13 has a second drive pulse PS2, and the fourth waveform section SS14 has a first dummy pulse DP1.

  The second drive signal COM_B includes a first waveform section SS21 generated in the period T1, a second waveform section SS22 generated in the period T2, a third waveform section SS23 generated in the period T3, and a period T4. And a fourth waveform section SS24 generated in Each waveform part SS21 to SS24 of the second drive signal COM_B also has a pulse for causing the piezo element 417 to perform a predetermined operation. That is, the first waveform section SS21 has a third drive pulse PS3, and the second waveform section SS22 has a fourth drive pulse PS4. The third waveform section SS23 has a second dummy pulse DP2, and the fourth waveform section SS24 has a fifth drive pulse PS5.

  Here, the first driving pulse PS1 to the fifth driving pulse PS5 cause the piezo element 417 to perform an ejection operation for ejecting ink. The minute vibration pulse VP is for displacing the meniscus (the free surface of the ink exposed by the nozzle Nz) to the extent that ink is not ejected. The first dummy pulse DP1 and the second dummy pulse DP2 are not selected depending on the dot formation data SI, but in order to eject ink when they are selected by mistake instead of the second drive pulse PS2 or the fifth drive pulse PS5. The discharge operation is performed by the piezo element 417. The drive signals COM_A and COM_B, the drive pulses PS1 to PS5, the dummy pulses DP1 and DP2, etc. will be described in detail later.

<About the head controller HC>
Next, the head controller HC will be described. Here, FIG. 7 is a block diagram illustrating the configuration of the head controller HC. FIG. 8 is an explanatory diagram of the control logic 84. FIG. 9 is an explanatory diagram of the decoder 83.

  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 first switch 85A, A second switch 85B is provided. Each part excluding 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 first switch 85A, and the second switch 85B). ) Is provided for each piezo element 417. Here, a set of the first switch 85A and the second switch 85B provided in the same piezo element 417 corresponds to a switch unit. The first switch 85A corresponds to a switch that controls application of the first drive signal COM_A as a drive signal to the piezo element 417. The second switch 85B corresponds to another switch that controls application of the second drive signal COM_B as another drive signal to the piezo element 417. Since the piezo element 417 is provided for each nozzle Nz, it can be said that these parts are also provided for each nozzle Nz.

  The head controller HC performs control for ejecting ink based on a head control signal (such as dot formation data SI and a latch signal LAT) from the printer-side controller 60. That is, the head control unit HC controls the first switch 85A and the second switch 85B based on the dot formation data SI indicating the ink ejection amount, and determines the necessary portions of the first drive signal COM_A and the second drive signal COM_B. This is selectively applied to the piezo element 417. Thereby, a pulse included in each drive signal COM is selectively applied to the piezo element 417 (described later).

  The dot formation data SI is sent to the recording head 41 in synchronization with the transfer clock CLK. In the dot formation data SI sent, the upper bit group is set in each first shift register 81A, and the lower bit group is set in each 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 (that is, when a latch pulse is applied), each first latch circuit 82A latches the upper bit of the corresponding dot formation data SI, and each first The two latch circuits 82B latch the lower bits of the corresponding dot formation data SI. The dot formation data SI (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 dot formation data SI, and controls a switch control signal SW (first switch control signal SW_A, second switch) for controlling the first switch 85A and the second switch 85B. Control signal SW_B, see FIG. 9). The switch control signal SW corresponds to selection information for selecting a necessary portion from the first drive signal COM_A and the second drive signal COM_B.

  Here, the control logic 84 and the selection data q0 to q7 stored in the control logic 84 will be described. As shown in FIG. 8, the control logic 84 includes a plurality of registers RG that can store 1-bit data. Each register RG is configured by, for example, a D-FF (delay flip flop) circuit. Each register RG stores predetermined selection data. The selection data q0 to q7 are sent from the printer-side controller 60, similarly to the dot formation data SI. The contents of the selection data q0 to q7 are changed when the print mode is changed, for example.

  For convenience of explanation, in FIG. 8, each register RG is arranged in a matrix of four in the column direction (vertical direction) and eight in the row direction (horizontal direction). Then, four registers RG belonging to the same column are grouped, and are shown with reference numerals Q0 to Q7 in order from the left group. Each register RG is divided into a register group (groups Q0 to Q3) located on the left side in the row direction and a register group (groups Q4 to Q7) located on the right side in the row direction. For the register group located on the left side, four registers RG belonging to the same row are grouped, and symbols G11 to G14 are given in order from the group located on the upper side. Similarly, the register group located on the right side is also grouped and denoted by reference numerals G21 to G24 in order from the group located on the upper side.

  The above grouping is performed based on the role of each register RG. First, each register RG belonging to the group Q0 to group Q3 located on the left side in the row direction can store the first selection data q0 to q3 for the first drive signal COM_A. Further, the registers RG belonging to the groups Q4 to Q7 located on the right side in the row direction can store the second selection data q4 to q7 for the second drive signal COM_B.

  Furthermore, the registers RG belonging to the same column can store selection data q0 to q7 used in the same ejection operation. More specifically, each of the registers RG belonging to the group Q0 and the group Q4 can store selection data q0 and q4 corresponding to no dot (no ink ejection). Each of the registers RG belonging to the group Q1 and the group Q5 can store selection data q1 and q5 corresponding to ejection of small dot ink (formation of small dots). Similarly, each register RG belonging to group Q2 and group Q6 receives selection data q2 and q6 corresponding to ejection of medium dot ink (formation of medium dot), and each register RG belonging to group Q3 and group Q7 Selection data q3 and q7 corresponding to ejection of large dot ink (formation of large dots) can be stored.

  Further, the registers RG belonging to the same row can store selection data for the same waveform section. More specifically, each register RG belonging to the group G11 can store selection data for the first waveform section SS11 generated in the period T1. Each register RG belonging to the group G12 can store selection data for the second waveform section SS12 generated in the period T2. Further, each register RG belonging to the group G13 generates selection data for the third waveform section SS13 generated in the period T3, and each register RG belonging to the group G14 uses the selection data for the fourth waveform section SS14 generated in the period T4. Each of the selection data can be stored. Similarly, each register RG belonging to the group G21 can store selection data for the first waveform section SS21 generated in the period T1, and each register RG belonging to the group G22 is generated in the period T2. Selection data for the second waveform section SS22 can be stored. Each register RG belonging to the group G23 can store selection data for the third waveform section SS23 generated in the period T3, and each register RG belonging to the group G24 is generated in the period T4. Selection data for the four waveform sections SS24 can be stored.

  Summarizing the above, each register RG included in the control logic 84 has a corresponding type of drive signal COM (first drive signal COM_A, second drive signal COM_B) and corresponding dot formation data SI (data [00] to data [00]. 11]), the selection data determined by each factor of the corresponding waveform portion (the first waveform portion SS11, the second waveform portion SS22, etc.) is stored.

  For example, the registers RG (Q0, G11) belonging to both the group Q0 and the group G11 correspond to the first waveform portion SS11 of the first drive signal COM_A in the dot formation data SI (data [00]) without dots. Selection data is stored. The registers RG (Q3, G13) belonging to both the group Q3 and the group G13 correspond to the third waveform portion SS13 of the first drive signal COM_A in the large dot formation data SI (data [11]). Selection data is stored. The registers RG (Q7, G22) belonging to both the group Q7 and the group G22 correspond to the second waveform portion SS22 of the second drive signal COM_B in the large dot formation data SI (data [11]). Selection data is stored.

  The selection data stored in these registers RG is defined by the multiplexer MX0 to the multiplexer MX7 as a latch pulse included in the latch signal LAT, a change pulse included in the first change signal CH_A, and a change pulse included in the second change signal CH_B. Are selected sequentially at the timings. That is, the timing defined by these pulses corresponds to the switching timing of the drive signal COM applied to the piezo element 417. In this embodiment, the selection operation by the multiplexers MX0 to MX7 is controlled by outputs from the counters CTA and CTB to which the latch signal LAT and the change signals CH_A and CH_B are input. The selection data selected by the multiplexer MX0 to the multiplexer MX7 is output as first selection data q0 to q3 for the first drive signal COM_A and second selection data q4 to q7 for the second drive signal COM_B. . The contents of the selection data q0 to q7 will be described later.

  Next, the decoder 83 will be described. The decoder 83 selects the one corresponding to the latched dot formation data SI from the first selection data q0 to q3 and the second selection data q4 to q7, and outputs it as the switch control signal SW. As shown in FIG. 9, the decoder 83 includes a first decoding unit 83A that outputs a first switch control signal SW_A and a second decoding unit 83B that outputs a second switch control signal SW_B.

  The first decoding unit 83A has four AND gates 831A to 834A and one OR gate 835A. Each of the AND gates 831A to 834A has three input terminals and one output terminal.

The AND gate 831A receives the first selection data q0 for no dot, the inverted data of the upper bits of the dot formation data SI, and the inverted data of the lower bits. Therefore, when the dot formation data SI is data [00], the output from the AND gate 831A has contents according to the first selection data q0 for no dot.
The AND gate 832A receives first selection data q1 for small dots, inverted data of upper bits of dot formation data SI, and lower bit data. For this reason, when the dot formation data SI is data [01], the output from the AND gate 832A has contents according to the first selection data q1 for small dots.
The AND gate 833A receives the medium dot first selection data q2, the upper bit data of the dot formation data SI, and the lower bit inverted data. Therefore, when the dot formation data SI is data [10], the output from the AND gate 833A has contents according to the medium dot first selection data q2.
The AND gate 834A receives the first selection data q3 for large dots, the upper bit data of the dot formation data SI, and the lower bit data. Therefore, when the dot formation data SI is data [11], the output from the AND gate 834A has the contents according to the first selection data q3 for large dots.

  The OR gate 835A has four input terminals and one output terminal. The outputs from the AND gates 831A to 834A are input to each of the four input terminals. A first switch control signal SW_A is output from the OR gate 835A. That is, among the first selection data q0 to q3, the data corresponding to the latched dot formation data SI is output as the first switch control signal SW_A.

  The second decoding unit 83B also includes four AND gates 831B to 834B and one OR gate 835B. The configuration of the second decoding unit 83B is the same as the configuration of the first decoding unit 83A. That is, the second selection data q4 for no dot, the inverted data of the upper bits of the dot formation data SI, and the inverted data of the lower bits are input to the AND gate 831B. The AND gate 832B receives the second selection data q5 for small dots, the inverted data of the upper bits of the dot formation data SI, and the lower bit data. The AND gate 833B receives the second selection data q6 for medium dots, the upper bit data of the dot formation data SI, and the inverted data of the lower bits. The AND gate 834B receives the second selection data q7 for large dots, the upper bit data of the dot formation data SI, and the lower bit data. Outputs from the four AND gates 831B to 834B are input to the OR gate 835B. As a result, the OR gate 835B outputs the second selection data q4 to q7 corresponding to the latched dot formation data SI as the second switch control signal SW_B.

  The first switch control signal SW_A and the second switch control signal SW_B output from the decoder 83 are input to the first switch 85A and the second switch 85B. The first switch 85A and the second switch 85B switch between an on state and an off state by changing a resistance value. For example, the resistance value is about 100Ω in the on state, and the resistance value is several tens of MΩ in the off state. The first drive signal COM_A from the drive signal generation circuit 70 is applied to the input side of the first switch 85A, and the second drive signal COM_B is applied to the input side of the second switch 85B. A piezo element 417 is electrically connected to the common output side of the first switch 85A and the second switch 85B. The first switch 85A and the second switch 85B are provided for each drive signal COM to be generated. The first switch 85A controls application of the first drive signal COM_A to the piezo element 417, and the second switch 85B controls application of the second drive signal COM_B to the piezo element 417. That is, the first switch control signal SW_A corresponds to a switch control signal for the first switch 85A, and the second switch control signal SW_B corresponds to another switch control signal for the second switch 85B. Specifically, when the first switch control signal SW_A is data [1], the first switch 85A is turned on and the first drive signal COM_A is applied to the piezo element 417. When the first switch control signal SW_A is data [0], the first switch 85A is turned off, so that the first drive signal COM_A is not applied to the piezo element 417. Similarly, when the second switch control signal SW_B is data [1], the second switch 85B is turned on, and the second drive signal COM_B is applied to the piezo element 417. When the second switch control signal SW_B is data [0], the second switch 85B is turned off, so that the second drive signal COM_B is not applied to the piezo element 417.

  The printer-side controller 60 controls the switches 85A and 85B, so that the waveform portions SS11 to SS14 constituting the first drive signal COM_A and the waveform portions SS21 to SS24 constituting the second drive signal COM_B are piezo-electric. It is selectively applied to the element 417. That is, the decoder 83 selects a corresponding set of selection data from the plurality of selection data q0 to q7 based on the dot formation data SI from the printer-side controller 60, and the first switch control signal SW_A and the second switch Output as control signal SW_B. Based on the first switch control signal SW_A and the second switch control signal SW_B, the first switch 85A and the second switch 85B change the necessary part of the first drive signal COM_A and the necessary part of the second drive signal COM_B. 417 is selectively applied.

  Therefore, the decoder 83, the first switch 85A, and the second switch 85B included in the head controller HC function as a drive pulse applying unit. By adopting such a configuration, the necessary portion of the first drive signal COM_A and the necessary portion of the second drive signal COM_B can be applied to the piezo element 417 with simple control.

  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. In other words, during the period when 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.

<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, an image is printed on the paper S by controlling the control target portion. Here, FIG. 10 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, which is an object to be printed, and positioning it at the print start 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, the first drive signal COM_A and the second drive signal COM_B are generated, and necessary portions of these drive signals COM are selectively applied to the piezo element 417. Then, 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 controls 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 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.

=== Characteristics of the present embodiment ===
Next, features of the present embodiment will be described. Here, FIG. 11 is a diagram for explaining the waveforms of the first drive signal COM_A and the second drive signal COM_B generated by the drive signal generation circuit 70 and the contents of the switch control signal SW.

  The printer 1 having the above-described configuration is configured to selectively apply the necessary portion of the first drive signal COM_A and the necessary portion of the second drive signal COM_B to the piezo element 417. For this reason, when the first drive signal COM_A should be selected, the second drive signal COM_B may be selected and applied to the piezo element 417. For example, the contents of the selection data q0 to q7 and the switch control signal SW have been rewritten due to noise or the like. Here, when the erroneously selected portion is a waveform portion having a constant potential, ink is not ejected. This results in a missing dot state.

  Therefore, in this printer 1, dummy pulses are included in the waveform portions that are not selected by the selection data q0 to q7. The dummy pulse is applied to the piezo element 417 to cause the piezo element 417 to perform an ink ejection operation. In this example, the first dummy pulse DP1 is included in the first drive signal COM_A, and the second dummy pulse DP2 is included in the second drive signal COM_B.

  Here, as for the first dummy pulse DP1, the second drive signal COM_B should be selected in the period T4 and the fifth drive pulse PS5 should be applied to the piezo element 417. This is a pulse applied to the piezo element 417 when the signal COM_A is selected. By including such first dummy pulse DP1 in the first drive signal COM_A, even if the first drive signal COM_A is erroneously selected in the period T4, the first dummy pulse DP1 is the fifth. Instead of the drive pulse PS5, an ink ejection operation is performed.

  Similarly, in the second dummy pulse DP2, the first drive signal COM_A should be selected in the period T3 and the second drive pulse PS2 should be applied to the piezo element 417. This is a pulse applied to the piezo element 417 when the signal COM_B is selected. In addition, since the second dummy pulse DP2 is included in the second drive signal COM_B, even if the second drive signal COM_B is erroneously selected in the period T3, the second dummy pulse DP2 is driven to the second drive signal COM_B. An ink ejection operation is performed instead of the pulse PS2.

  As a result, even if the drive signal COM is erroneously selected in the period T3 or the period T4, it is possible to prevent a problem that ink is not ejected. Details will be described below.

<Regarding the first drive signal COM_A and the second drive signal COM_B>
First, the first drive signal COM_A and the second drive signal COM_B will be described with reference to FIG. As described above, the first drive signal COM_A includes the first waveform section SS11 generated in the period T1, the second waveform section SS12 generated in the period T2, and the third waveform section SS13 generated in the period T3. And a fourth waveform section SS14 generated in the period T4. The first waveform section has a first drive pulse PS1 generated in the period T1a, and the second waveform section has a minute vibration pulse VP generated in the period T2a. The third waveform portion has the second drive pulse PS2 generated in the period T3a, and the fourth waveform portion has the first dummy pulse DP1 generated in the period T4a. The second drive signal COM_B includes a first waveform section SS21 generated in the period T1, a second waveform section SS22 generated in the period T2, a third waveform section SS23 generated in the period T3, and a period T4. And a fourth waveform section SS24 generated in The first waveform section SS21 has a third drive pulse PS3 generated in the period T1b, and the second waveform section SS22 has a fourth drive pulse PS4 generated in the period T2b. The third waveform section SS23 has a second dummy pulse DP2 generated in the period T3b, and the fourth waveform section SS24 has a fifth drive pulse PS5 generated in the period T4b.

  The first drive pulse PS1 to the fifth drive pulse PS5 are for ejecting ink from the nozzles Nz. That is, when these first drive pulse PS1 to fifth drive pulse PS5 are applied, the piezo element 417 performs an operation for ejecting ink. Among these drive pulses, the first drive pulse PS1, the second drive pulse PS2, the fourth drive pulse PS4, and the fifth drive pulse PS5 have the same waveform. For this reason, when each drive pulse is applied to the piezo element 417, the same amount of ink is ejected. In this embodiment, every time one drive pulse is applied to the piezo element 417, 7 pL of ink is ejected from the nozzle Nz. These drive pulses PS1, PS2, PS4, and PS5 are applied to the piezo element 417 when medium dots are formed on the paper S and when large dots are formed on the paper S. That is, when forming a medium dot on the paper S, the second drive pulse PS2 is selected from the first drive signal COM_A, and the fourth drive pulse PS4 is selected from the second drive signal COM_B, and applied to the piezo element 417. Is done. Further, when forming a large dot on the paper S, the first drive pulse PS1 and the second drive pulse PS2 from the first drive signal COM_A, and the fourth drive pulse PS4 and the fifth drive from the second drive signal COM_B. The pulse PS5 is selected and applied to the piezo element 417.

  The third drive pulse PS3 is applied to the piezo element 417 when forming small dots on the paper S. That is, when forming small dots on the paper S, the third drive pulse PS3 is selected from the second drive signal COM_B and applied to the piezo element 417. When the third drive pulse PS3 is applied to the piezo element 417, 3 pL of ink is ejected from the nozzle Nz.

  The fine vibration pulse VP is for displacing the meniscus to the extent that ink is not ejected. The micro-vibration pulse VP of this embodiment has a trapezoidal waveform. When the fine vibration pulse VP is applied, the piezoelectric element 417 is deformed to cause pressure fluctuation in the ink in the pressure chamber 414a, and the meniscus is displaced. The ink in the vicinity of the nozzle Nz is agitated by the displacement of the meniscus, and thickening of the ink in the vicinity of the nozzle Nz is prevented.

  When the first dummy pulse DP1 and the second dummy pulse DP2 are selected by mistake instead of the second drive pulse PS2 and the fifth drive pulse PS5, the piezo element 417 performs an ejection operation for ejecting ink. Is. The first dummy pulse DP1 causes the piezo element 417 to perform an ejection operation when it is selected by mistake instead of the fifth drive pulse PS5. In the present embodiment, the first dummy pulse DP1 is generated in the same period as the fifth drive pulse PS5. That is, the generation period T4a of the first dummy pulse DP1 has the same length as the generation period T4b of the fifth drive pulse PS5. The generation start timing and the generation end timing are also the same. In addition, the first dummy pulse DP1 has a waveform having the same shape as that of the fifth drive pulse PS5. For this reason, even if the first dummy pulse DP1 is selected by mistake, the piezo element 417 can perform the same ejection operation as when the fifth pulse is applied. The second dummy pulse DP2 causes the piezo element 417 to perform an ejection operation when the second dummy pulse DP2 is erroneously selected instead of the second drive pulse PS2. The second dummy pulse DP2 is generated in the same period as the second drive pulse PS2. That is, the generation period T3b of the second dummy pulse DP2 has the same length as the generation period T3a of the second drive pulse PS2, and the generation start timing and the generation end timing are also the same. The second dummy pulse DP2 has the same shape as that of the second drive pulse PS2. For this reason, even if the second dummy pulse DP2 is selected by mistake, the piezo element 417 can perform the same ejection operation as when the second pulse is applied.

  From the above description, the fifth drive pulse PS5 is generated in a certain period and corresponds to a drive pulse for causing the piezo element 417 to perform an ejection operation, and the first dummy pulse DP1 is generated in a certain period. Thus, it can be said that this corresponds to a dummy pulse that causes the piezo element 417 to perform an ejection operation when it is selected by mistake instead of the drive pulse described above. The second driving pulse PS2 is generated in another period and corresponds to another driving pulse for causing the piezo element 417 to perform the ejection operation, and the second dummy pulse DP2 is generated in another period and is described above. It can be said that this corresponds to another dummy pulse that causes the piezo element 417 to perform an ejection operation when it is selected by mistake instead of the other driving pulse.

<About selection data q0 to q7>
Next, the contents of the selection data q0 to q7 will be described. The selection data q0 to q7 is composed of 4-bit data indicating application or non-application of the waveform portion for each of the periods T1 to T4. The data of each bit is updated at the timing of the latch pulse included in the latch signal LAT and the change pulse included in the first change signal CH_A and the second change signal CH_B. Here, the data of each bit is configured by either data [1] indicating application of the corresponding waveform portion or data [0] indicating non-application of the corresponding waveform portion. The most significant bit indicates application or non-application of the first waveform section SS11 (q0 to q3) or the first waveform section SS21 (q4 to q7) generated in the period T1. The second bit from the upper side indicates application or non-application of the second waveform section SS12 or the second waveform section SS22 generated in the period T2. Similarly, the third bit from the upper side is applied or not applied to the third waveform section SS13 or the third waveform section SS23 generated in the period T3, and the least significant bit is the fourth waveform generated in the period T4. Application and non-application of the part SS14 or the fourth waveform part SS24 are shown.

  The selection data q0 is defined in data [0100]. The selection data q0 is not applied to the first waveform portion SS11 of the first drive signal COM_A (data [0]), applied to the second waveform portion SS12 (data [1]), the third waveform portion SS13, and the fourth waveform. Control is performed so that the portion SS14 is not applied (data [0]). The selection data q1 is defined in data [0000]. The selection data q1 is controlled so as not to be applied to each waveform portion from the first waveform portion SS11 to the fourth waveform portion SS14. The selection data q2 is defined in data [0010]. The selection data q2 is controlled so that it is not applied to the first waveform section SS11 and the second waveform section SS12, is applied to the third waveform section SS13, and is not applied to the fourth waveform section SS14. The selection data q3 includes data [1010]. The selection data q3 is controlled to be applied to the first waveform portion SS11 and the third waveform portion SS13 and not applied to the second waveform portion SS12 and the fourth waveform portion SS14.

  The selection data q4 is composed of data [0000]. The selection data q4 is controlled to be not applied to each waveform part from the first waveform part SS21 to the fourth waveform part SS24 of the second drive signal COM_B. The selection data q5 is composed of data [1000]. The selection data q5 is controlled to be applied to the first waveform section SS21 and not applied to each waveform section from the second waveform section SS22 to the fourth waveform section SS24. The selection data q6 is composed of data [0100]. The selection data q6 is controlled so that it is not applied to the first waveform section SS21, is applied to the second waveform section SS22, and is not applied to the third waveform section SS23 and the fourth waveform section SS24. The selection data q7 is composed of data [0101]. The selection data q7 is controlled to be non-applied to the first waveform portion SS21 and the third waveform portion SS23, and applied to the second waveform portion SS22 and the fourth waveform portion SS24.

  As can be seen from the above description, for the first dummy pulse DP1 and the second dummy pulse DP2, data [0] indicating non-application is set in any dot formation data SI. That is, it can be said that the first dummy pulse DP1 and the second dummy pulse DP2 are pulses that are not applied to the piezo element 417 depending on the selection data (switch control signal SW).

<Application of Drive Signal COM to Piezoelectric Element 417>
Next, application of the drive signal COM to the piezo element 417 based on the switch control signal SW will be described. Here, FIG. 12 is a diagram showing a waveform portion applied to the piezo element 417 for each content of the dot formation data SI.

  First, the case where the dot formation data SI is data [00] indicating no dot will be described. In this case, the selection data q0 becomes the first switch control signal SW_A, and the selection data q4 becomes the second switch control signal SW_B. Therefore, application of the first drive signal COM_A to the piezo element 417 is controlled based on the selection data q0, and application of the second drive signal COM_B to the piezo element 417 is controlled based on the selection data q4. For this reason, the second waveform portion SS12 of the first drive signal COM_A is applied to the piezo element 417 in the period T2, and the meniscus is finely vibrated based on the fine vibration pulse VP.

  Next, the case where the dot formation data SI is data [01] indicating the formation of small dots will be described. In this case, the selection data q1 becomes the first switch control signal SW_A, and the selection data q5 becomes the second switch control signal SW_B. Therefore, the first waveform portion SS21 of the second drive signal COM_B is applied to the piezo element 417 in the period T1, and an amount of ink necessary for forming a small dot is ejected from the nozzle Nz based on the third drive pulse PS3. Is done.

  Next, the case where the dot formation data SI is data [10] indicating the formation of medium dots will be described. In this case, the selection data q2 becomes the first switch control signal SW_A, and the selection data q6 becomes the second switch control signal SW_B. For this reason, the third waveform portion SS13 of the first drive signal COM_A is applied to the piezo element 417 in the period T3, and the fourth waveform portion SS24 of the second drive signal COM_B is applied to the piezo element 417 in the period T4. As a result, an amount of ink necessary for forming a medium dot is ejected from the nozzle Nz based on the second drive pulse PS2 and the fifth drive pulse PS5.

  Finally, the case where the dot formation data SI is data [11] indicating the formation of large dots will be described. In this case, the selection data q3 becomes the first switch control signal SW_A, and the selection data q7 becomes the second switch control signal SW_B. Therefore, the first waveform portion SS11 of the first drive signal COM_A and the third waveform portion SS13 of the first drive signal COM_A are applied to the piezo element 417 in the period T1, respectively. In addition, the second waveform portion SS22 of the second drive signal COM_B is applied to the piezoelectric element 417 in the period T2, and the fourth waveform portion SS24 of the second drive signal COM_B is applied to the piezoelectric element 417 in the period T4. As a result, based on the first drive pulse PS1, the second drive pulse PS2, the fourth drive pulse PS4, and the fifth drive pulse PS5, an amount of ink necessary for forming a large dot is ejected from the nozzle Nz.

<Dummy pulse function>
Next, functions of the first dummy pulse DP1 and the second dummy pulse DP2 will be described. Here, FIG. 13A is a diagram for schematically explaining the function of the first dummy pulse DP1. FIG. 13B is a diagram for schematically explaining the function of the second dummy pulse DP2. For convenience, the application control of the drive signal COM at the time of large dot formation will be described as an example.

  As described above, in the printer 1, the necessary portion of the first drive signal COM_A and the necessary portion of the second drive signal COM_B are selectively applied to the piezo element 417 according to the contents of the dot formation data SI. Yes. Here, the selective application of these drive signals COM is performed based on the first switch control signal SW_A and the second switch control signal SW_B. The selection data q0 to q3 that is the basis of the first switch control signal SW_A and the selection data q4 to q7 that are the basis of the second switch control signal SW_B are sent from the printer-side controller 60 and stored in the control logic 84. ing. For this reason, the contents of the selection data q0 to q7 may change due to noise received when sent from the printer-side controller 60, noise generated when switching by the multiplexer, and the like. In addition, the contents of the first switch control signal SW_A and the second switch control signal SW_B may be changed by noise. In addition, the contents of the selection data q0 to q7 may be different from the original contents due to a transfer timing shift or the like.

  The contents of the first switch control signal SW_A (selection data q0 to q3) and the second switch control signal SW_B (selection data q4 to q7) are changed in the first dummy pulse DP1 and the second dummy pulse DP2 due to noise or the like. In the event of a failure, it will prevent problems caused by it. For example, as shown in FIG. 13A, consider a case where the fourth waveform portion SS24 of the second drive signal COM_B is not selected and the fourth waveform portion SS14 of the first drive signal COM_A is selected in the period T4. In this case, the first dummy pulse DP1 is applied to the piezo element 417 instead of the fifth drive pulse PS5. As described above, the first dummy pulse DP1 causes the piezo element 417 to perform an ejection operation for ejecting ink. For this reason, by applying the first dummy pulse DP1, ink is ejected from the nozzle Nz. As a result, it is possible to prevent problems such as missing dots. The first dummy pulse DP1 ejects the same amount of ink as when the fifth drive pulse PS5 is applied to the piezo element 417. For this reason, even if the first dummy pulse DP1 is erroneously applied to the piezo element 417, dots of the same size can be formed. The first dummy pulse DP1 has the same shape as the fifth drive pulse PS5. For this reason, with respect to the ink ejected by the application of the first dummy pulse DP1, the flight speed, the flight direction, and the like can be made the same as when the fifth drive pulse PS5 is applied to the piezo element 417. As a result, it is possible to reliably prevent a problem that the image quality is impaired. In addition, since the waveform of the first dummy pulse DP1 and the waveform of the fifth drive pulse PS5 are the same, the application of the first dummy pulse DP1 is started during the application of the fifth drive pulse PS5. Even so, it is possible to prevent a problem that the potential of the piezo element 417 changes rapidly. Therefore, the piezo element 417 can be protected.

=== Other Embodiments ===
The above-described embodiment is mainly described with respect to the printing system 100 including the printer 1 as a liquid ejecting apparatus. However, the disclosure includes a liquid ejecting method, a liquid ejecting system, and the like. In addition, a program and a code for controlling the liquid ejection apparatus are also disclosed. Further, these embodiments are for facilitating the 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.

<Dummy pulse>
In the embodiment described above, the first drive signal COM_A has the first dummy pulse DP1 generated in the period T4. Further, the second drive signal COM_B has the second dummy pulse DP2 generated in the period T3. In other words, the dummy pulse is not included in the period T1 and the period T2. However, a dummy pulse may be included in these periods T1 and T2. In short, a dummy pulse can be included in any waveform portion that is not selected by the selection data q0 to q7.

  In the above-described embodiment, the first dummy pulse DP1 ejects the same amount of ink as the fifth drive pulse PS5, and the second dummy pulse DP2 ejects the same amount of ink as the second drive pulse PS2. there were. Specifically, the first dummy pulse DP1 has the same shape as the fifth drive pulse PS5, and the second dummy pulse DP2 has the same shape as the second drive pulse PS2. Here, from the viewpoint of preventing missing dots, the drive pulse corresponding to the dummy pulse may not eject the same amount of ink or may not have the same waveform. In addition, the generation timing may be slightly shifted. For example, it may be generated within one waveform portion.

  If the same amount of ink is ejected by the dummy pulse and the corresponding drive pulse as in the above-described embodiment, even if the dummy pulse is applied to the piezo element 417, the size of the dot Can be aligned with when the corresponding drive pulse is applied to the piezo element 417. In addition, when the waveform having the same shape is used for the dummy pulse and the corresponding driving pulse, the flying speed and the flying direction of the ink can be aligned with those when the corresponding driving pulse is applied to the piezo element 417. Further, if the dummy pulse and the corresponding drive pulse have the same waveform and the generated timing is the same, the ink landing position is aligned with that when the corresponding drive pulse is applied to the piezo element 417. be able to. In addition, even if the state of each of the switches 85A and 85B changes while the drive pulse is being applied to the piezo element 417, and a dummy pulse is applied to the piezo element 417, a sudden potential change with respect to the piezo element 417 occurs. And the piezo element 417 can be protected.

<About the drive signal COM>
In the above-described embodiment, the drive signal generation circuit 70 generates two types of signals, the first drive signal COM_A and the second drive signal COM_B. Here, the drive signal COM generated from the drive signal generation circuit 70 may be three or more types. Even when three or more types of drive signals COM are generated, the same effect can be obtained by including a dummy pulse in a waveform portion that is not selected depending on selection data.

<Elements that perform discharge operation>
In the above-described embodiment, the piezo element 417 is exemplified as the element that performs the ejection operation. Here, the element that performs the ejection operation is not limited to the piezo element 417. For example, it may be a heating element for heating a liquid. In this case, dot missing can be prevented by including a dummy pulse in a waveform portion that is not selected depending on selection data.

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

  Even in these apparatuses, it is possible to prevent problems caused by the fact that liquid is not discharged. Then, as in the above-described embodiment, it is possible to prevent defects such as missing dots by using a liquid ink for printing and a medium (paper S or the like) on which an object is printed as an object.

1 is a diagram illustrating a configuration of a printing system. It is a block diagram explaining the structure of a computer and a printer. FIG. 3A is a diagram illustrating the configuration of the printer. FIG. 3B is a side view illustrating the configuration of the printer. It is sectional drawing for demonstrating the structure of a head. It is a figure for demonstrating arrangement | positioning of the nozzle which a head has. FIG. 6A is a block diagram for explaining the configuration of the drive signal generation circuit. FIG. 6B is a diagram for describing configurations of a first waveform generation circuit and a second waveform generation circuit included in the drive signal generation circuit. FIG. 6C is a diagram for describing a configuration of the first current amplifier circuit and the second current amplifier circuit. It is a block diagram explaining the structure of a head control part. It is explanatory drawing of a control logic. It is explanatory drawing of a decoder. It is a flowchart explaining printing operation. It is a figure for demonstrating the waveform of the 1st drive signal and 2nd drive signal which are produced | generated by a drive signal generation circuit, and the content of a switch control signal. It is a figure which shows the waveform part applied to a piezo element. FIG. 13A is a diagram for schematically explaining the function of the first dummy pulse. FIG. 13B is a diagram for schematically explaining the function of the second dummy pulse.

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 idler 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 head case,
50 detector groups, 51 linear encoder, 52 rotary encoder,
53 Paper detector, 54 Paper width detector,
60 printer-side controller, 61 interface unit, 62 CPU,
63 memory, 64 control unit,
70 drive signal generation circuit, 70A first drive signal generation unit,
71A first waveform generation circuit, 711A digital analog converter,
712A voltage amplifier circuit, 72A first current amplifier circuit,
721A first transistor pair, 70B second drive signal generation unit,
71B second waveform generation circuit, 711B digital-analog converter,
712B voltage amplification circuit, 72B second current amplification circuit,
721B second transistor pair,
81A first shift register, 81B second shift register,
82A first latch circuit, 82B second latch circuit, 83 decoder,
83A 1st decoding part, 831A-834A AND gate,
835A OR gate, 83B second decoding unit,
831B-834B AND GATE, 835B OR GATE,
84 control logic, 85A first switch, 85B second switch,
100 printing system, 110 computer, 111 host side controller,
112 interface unit, 113 CPU, 114 memory,
120 display devices, 130 input devices, 131 keyboards,
132 mouse, 140 recording and playback device,
141 flexible disk drive device,
142 CD-ROM drive device,
S paper, SI dot formation data, CTR controller board,
HC head controller, CR carriage, Nk first nozzle row,
Ny second nozzle row, Nc third nozzle row, Nm fourth nozzle row,
Tr1 NPN type transistor, Tr2 PNP type transistor,
RG register, CLK clock, SI dot formation data,
LAT latch signal, CH_A first change signal, CH_B second change signal,
SW switch control signal, SW_A first switch control signal,
SW_B second switch control signal, COM drive signal,
COM_A first drive signal, SS11 first waveform section, SS12 second waveform section,
SS13 third waveform section, SS14 fourth waveform section,
COM_B second drive signal, SS21 first waveform section, SS22 second waveform section,
SS23 3rd waveform part, SS24 4th waveform part, VP micro vibration pulse,
PS1 first drive pulse, PS2 second drive pulse, PS3 third drive pulse,
PS4 4th drive pulse, PS5 5th drive pulse,
DP1 first dummy pulse, DP2 second dummy pulse

Claims (13)

(A) an element that performs a discharge operation for discharging liquid;
(B) a drive signal having a drive pulse generated in a certain period and causing the element to perform the ejection operation;
Another drive pulse generated in another period that causes the element to perform the ejection operation, and a dummy pulse generated in the certain period that is erroneously replaced with the drive pulse Other drive signals having dummy pulses that cause the element to perform the ejection operation, and
A drive signal generator for generating
A liquid ejection apparatus having (C). The liquid ejection device according to claim 1,
Applying the drive pulse and the other drive pulse to the element by applying the necessary part of the drive signal selected based on the selection information and the necessary part of the other drive signal to the element, and applying the drive pulse. A liquid ejection apparatus having a portion. The liquid ejection device according to claim 2,
The drive pulse applying unit is
A switch for controlling application of the drive signal to the element, and another switch for controlling application of the other drive signal to the element;
A liquid ejection apparatus that controls the switch and the other switch based on the selection information, and applies the necessary part of the drive signal and the necessary part of the other drive signal to the element. The liquid ejection device according to any one of claims 1 to 3,
The dummy pulse is
A liquid ejecting apparatus for ejecting the same amount of liquid as the driving pulse. The liquid ejection device according to claim 4,
The dummy pulse is
A liquid ejection apparatus having a waveform having the same shape as the drive pulse. A liquid ejection apparatus according to any one of claims 1 to 5,
The drive signal is
A liquid ejecting apparatus, comprising: another dummy pulse that causes the element to perform the ejection operation when another dummy pulse generated in the other period is erroneously selected in place of the other driving pulse. The liquid ejection device according to claim 6,
The other dummy pulse is
A liquid ejecting apparatus for ejecting the same amount of liquid as the other driving pulses. The liquid ejection apparatus according to claim 7,
The other dummy pulse is
A liquid ejection apparatus having a waveform having the same shape as the other drive pulses. The liquid ejection device according to any one of claims 1 to 8,
The element is
A liquid ejection device that is a piezo element. A liquid ejection apparatus according to any one of claims 1 to 9,
The liquid is
A liquid ejection device, which is a liquid ink for printing. (A) an element configured by a piezo element and performing a discharge operation for discharging a liquid;
(B) a drive signal having a drive pulse generated in a certain period and causing the element to perform the ejection operation;
Another drive pulse generated in another period and causing the element to perform the ejection operation, and a dummy pulse generated in the certain period and having the same amount as the drive pulse And a dummy pulse for causing the element to perform the ejection operation when the waveform is the same shape as the drive pulse and is selected by mistake instead of the drive pulse. With other drive signals,
A drive signal generator for generating
(C) having a switch for controlling application of the drive signal to the element, and another switch for controlling application of the other drive signal to the element;
By applying the necessary part of the drive signal and the necessary part of the other drive signal selected by controlling the switch and the other switch based on the selection information to the element, the drive pulse and the other A drive pulse applying unit for applying a drive pulse to the element;
Have
(D) The drive signal is:
The other dummy pulse generated in the other period is for discharging the same amount of liquid as the other driving pulse, and has the same shape as the other driving pulse, In the case where it is selected by mistake instead of the other drive pulse, it has another dummy pulse that causes the element to perform the ejection operation,
(E) The liquid is
Liquid ink for printing,
(F) Liquid ejection device. (A) a drive signal having a drive pulse that is generated in a certain period and that causes the element that performs a discharge operation to discharge liquid to perform the discharge operation;
Another drive pulse generated in another period that causes the element to perform the ejection operation, and a dummy pulse generated in the certain period that is erroneously replaced with the drive pulse Other drive signals having dummy pulses that cause the element to perform the ejection operation, and
A step of generating
(B) selectively applying the drive pulse and the other drive pulse to the element based on selection information;
A liquid ejection method comprising: A program for a liquid ejection apparatus having an element that performs an ejection operation for ejecting liquid, a drive signal generation unit, and a drive pulse application unit,
(A) In the drive signal generator,
A drive signal having a drive pulse generated in a certain period and causing the element to perform the ejection operation;
Another drive pulse generated in another period that causes the element to perform the ejection operation, and a dummy pulse generated in the certain period that is erroneously replaced with the drive pulse Other drive signals having dummy pulses that cause the element to perform the ejection operation, and
Generating
(B) causing the drive pulse application unit to perform an operation of selectively applying the drive pulse and the other drive pulse to the element based on selection information;
A program that allows

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