JP2007237489A - Liquid ejector, liquid delivery method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejector which is able to suppress the power consumption of a liquid delivery head equipped with two or more elements for making a liquid delivered by an electric charge/discharge. <P>SOLUTION: The liquid ejector is equipped with a liquid delivery head (head 41), a power source (power supply section PWS) and an electric charge/discharge section (printer side controller 60, drive signal formation circuit 70, head control unit HC). The liquid delivery head is equipped with two or more elements for making the liquid delivered by the electric charge/discharge. The electric charge/discharge section forms the first and second drive signals for which a voltage change pattern is determined so that the electric charge period of the element made by the N-th waveform part of the first drive signal side and the electric charge period of the element made by the N-th waveform of the second drive signal side may not overlap each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

As a liquid discharge apparatus that discharges liquid from a liquid discharge head, for example, a printing apparatus, a color filter manufacturing apparatus, a staining apparatus, and a fine processing apparatus have been proposed. Such a liquid ejection device includes an element that operates to eject liquid by charging and discharging, and a drive signal generation unit that simultaneously generates a plurality of drive signals in a certain period (for example, a patent) See reference 1.) In this liquid ejecting apparatus, a plurality of waveform portions are generated in a period constituting a repeating unit. Then, by applying a necessary waveform portion, a desired operation is performed on the element to discharge the liquid.
JP 2000-52570 A

  In the liquid ejecting apparatus described above, the charging period of the element by the Nth waveform portion on one drive signal side overlaps with the charging period of the element by the Nth waveform portion on the other drive signal side. Accordingly, when an Nth waveform portion on one drive signal side is applied to a certain element and an Nth waveform portion on the other drive signal side is applied to another element, a certain element and another element Overlapping charging periods. Here, in the case where charging of a plurality of elements is performed by a common power source, the current flowing from the power source to each element increases during the charging period. The power consumption increases depending on the amount of current. For this reason, the charge period of a certain element overlaps with another element, resulting in an increase in power consumption.

  The present invention has been made in view of such circumstances, and an object thereof is to suppress power consumption.

The main invention for achieving the object is as follows:
(A) a liquid discharge head having a plurality of elements that operate to discharge liquid by charging and discharging;
(B) a power source used when charging the plurality of elements;
(C) a first drive signal having a plurality of waveform portions of voltage change patterns determined according to operations to be performed by the plurality of elements, and a voltage change pattern determined according to operations to be performed by the plurality of elements. Charging / discharging the plurality of elements by simultaneously generating a second drive signal having a plurality of waveform sections in a certain period and selectively applying a necessary waveform section to each of the plurality of elements A control unit,
The voltage change pattern is determined so that the charging period of the element by the Nth waveform portion on the first drive signal side and the charging period of the element by the Nth waveform portion on the second drive signal side do not overlap. A charge / discharge control unit for generating a first drive signal and the second drive signal;
(D).

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

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

That is, (A) a liquid discharge head having a plurality of elements that operate to discharge liquid by charging and discharging, (B) a power source used when charging the plurality of elements, and (C) the plurality of elements A first drive signal having a plurality of waveform portions of a voltage change pattern determined according to an operation to be performed, and a second drive signal having a plurality of waveform portions of a voltage change pattern determined according to an operation to be performed by the plurality of elements. A charge / discharge control unit configured to charge and discharge the plurality of elements by simultaneously generating a drive signal in a certain period and selectively applying a necessary waveform section to each of the plurality of elements; The voltage change pattern is determined such that the charging period of the element by the Nth waveform portion on the drive signal side and the charging period of the element by the Nth waveform portion on the second drive signal side do not overlap. Generating a driving signal and the second driving signal, and the charging and discharging control unit, it can be realized the liquid discharge apparatus having the (D).
According to such a liquid ejection apparatus, the charge / discharge control unit includes an element charging period by the Nth waveform portion on the first drive signal side and an element charging period by the Nth waveform portion on the second drive signal side. A first drive signal and a second drive signal having a voltage change pattern determined so as to avoid overlapping each other are generated. For this reason, the maximum value of the current flowing from the power supply to the element during charging can be made lower than in the past. As a result, power consumption can be suppressed.

In this liquid ejection apparatus, the charge / discharge control unit is charged / discharged by the second drive signal regardless of the element, and the first capacitor charged / discharged by the first drive signal regardless of the element. A configuration having a second capacitor is preferable.
According to such a liquid ejecting apparatus, the first capacitor and the second capacitor are charged and discharged regardless of the element, thereby preventing an oscillation phenomenon in the circuit. When charging these capacitors, the maximum value of the current flowing from the power source to these capacitors can be suppressed. As a result, power consumption can be reduced.

In this liquid discharge apparatus, the liquid discharge head includes a pressure chamber whose volume is changed by the operation of the element, and a nozzle communicated with the pressure chamber. The element is charged with the pressure chamber. A configuration that operates to contract the volume is preferable.
According to such a liquid ejection device, the pressure chamber is rapidly contracted when the liquid is ejected, so that the element is charged with a large current. At this time, since the charging periods of both waveform portions do not overlap, power consumption can be effectively suppressed.

In such a liquid discharge apparatus, the element is preferably a piezo element.
According to such a liquid ejection apparatus, the liquid ejection amount can be accurately controlled by charging and discharging.

In this liquid ejection apparatus, the charge / discharge control unit includes a drive signal generation unit that generates the first drive signal and the second drive signal, a plurality of waveform units included in the first drive signal, and the second A configuration having a signal applying unit that selects a necessary one from a plurality of waveform parts included in the drive signal in accordance with the discharge amount of the liquid and applies the selected waveform part to a certain element is preferable.
According to such a liquid ejection device, it is possible to select various waveform portions even during a limited period.

In this liquid ejection apparatus, the drive signal generation unit causes the element to perform an operation to be performed by the N-th waveform unit on the first drive signal side by the N-th waveform unit on the second drive signal side. It is preferable that the first drive signal and the second drive signal are generated differently from the operation to be performed.
According to such a liquid ejection device, the liquid ejection amount can be finely controlled even during a limited period.

In this liquid ejection apparatus, the drive signal generation unit makes the generation period of the Nth waveform portion on the first drive signal side different from the generation period of the Nth waveform portion on the second drive signal side. A configuration for generating the first drive signal and the second drive signal is preferable.
According to such a liquid ejecting apparatus, the degree of freedom regarding the waveform of each waveform section increases, and the operation performed by the element can be optimized.

In this liquid discharge apparatus, the liquid discharge head includes a plurality of elements that are operated to discharge liquid by charge / discharge and are divided into a plurality of groups, and the charge / discharge control A drive signal generation unit that generates the first drive signal and the second drive signal, and a necessary one selected from a plurality of waveform units included in the first drive signal according to a discharge amount of the liquid; A signal applying unit that applies to the elements belonging to the other group, selects a necessary one from a plurality of waveform parts included in the second drive signal according to the amount of liquid discharged, and applies to the elements belonging to the other group The structure having is preferable.
According to such a liquid ejecting apparatus, the elements belonging to a certain group and the elements belonging to another group are operated with different drive signals, so that the operation of the elements is adjusted for each group by adjusting the drive signals. it can. For example, the same operation can be performed by adjusting element characteristic variations for each group.

In this liquid ejection apparatus, the drive signal generation unit causes the element to perform an operation to be performed by the N-th waveform unit on the first drive signal side by the N-th waveform unit on the second drive signal side. The start timing of the operation by the Nth waveform portion on the first drive signal side is different from the start timing of the operation by the Nth waveform portion on the second drive signal side. The first drive signal in which the charging period of the element by the Nth waveform portion on the first drive signal side and the charging period of the element by the Nth waveform portion on the second drive signal side do not overlap. And the structure which produces | generates the said 2nd drive signal is preferable.
According to such a liquid ejecting apparatus, it is possible to suppress power consumption while causing the elements belonging to each group to perform the same operation.

In this liquid ejection apparatus, the drive signal generation unit is connected to the first voltage waveform generation unit that generates a first voltage waveform signal that is a basis of the first drive signal, and the power source, and the first A first current amplifying unit for amplifying a current of the voltage waveform signal; a second voltage waveform generating unit for generating a second voltage waveform signal which is a basis of the second drive signal; and the second power waveform connected to the power source. A configuration having a second current amplification unit that amplifies the current of the voltage waveform signal is preferable.
According to such a liquid ejecting apparatus, it is possible to generate the first drive signal and the second drive signal having a desired voltage waveform and sufficient current capacity for operating a plurality of elements.

Moreover, the following liquid discharge apparatus can also be realized.
That is, (A) a plurality of elements that perform an operation for discharging liquid by charging and discharging, a plurality of elements divided into a plurality of groups, a pressure chamber whose volume is changed by the operation of the elements, and the pressure A liquid discharge head having a nozzle communicated with the chamber, the liquid discharge head having a piezoelectric element that operates to contract the volume of the pressure chamber by charging as the element; A power source used when charging the element; (C) a first drive signal having a plurality of waveform portions of a voltage change pattern determined according to an operation to be performed by the plurality of elements; and an operation to be performed by the plurality of elements. Generating a second drive signal having a plurality of waveform portions of a voltage change pattern determined according to the same time period, and generating a necessary waveform portion for each of the plurality of elements A charge / discharge control unit that selectively charges and discharges the plurality of elements, wherein an operation to be performed by the N-th waveform unit on the first drive signal side is performed on the second drive signal side; Different from the operation performed by the N-th waveform section on the element, and the generation period of the N-th waveform section on the first drive signal side is defined as the generation period of the N-th waveform section on the second drive signal side. The first drive signal and the second drive signal which are different from each other, or the N-th waveform unit on the second drive signal side performs an operation to be performed on the element by the N-th waveform unit on the first drive signal side. The same operation as that performed by the element is performed, and the start timing of the operation by the Nth waveform portion on the first drive signal side is different from the start timing of the operation by the Nth waveform portion on the second drive signal side. In the first The first drive signal and the second drive signal are configured such that the charging period of the element by the Nth waveform portion on the dynamic signal side and the charging period of the element by the Nth waveform portion on the second drive signal side do not overlap. A drive signal generating unit that generates a drive signal, a plurality of waveform units included in the first drive signal, and a plurality of waveform units included in the second drive signal are selected according to the liquid discharge amount and selected. Applying the waveform portion to a certain element, or selecting a necessary one from a plurality of waveform portions included in the first drive signal according to the discharge amount of the liquid and applying it to the element belonging to a certain group, A signal applying unit that selects necessary ones from a plurality of waveform portions included in the second drive signal in accordance with a discharge amount of the liquid and applies them to the elements belonging to another group, and the first drive regardless of the elements First charge / discharge by signal And a second capacitor charged and discharged by the second drive signal regardless of the element, and the charging period of the element by the Nth waveform portion on the first drive signal side and the second drive signal A charge / discharge control unit that generates the first drive signal and the second drive signal in which the voltage change pattern is determined so that the charging period of the element by the N-th waveform unit on the side does not overlap. And (D) the drive signal generation unit is connected to the power source and a first voltage waveform generation unit that generates a first voltage waveform signal that is a basis of the first drive signal, and the first voltage waveform signal A first current amplifying unit for amplifying the current of the second driving signal; a second voltage waveform generating unit for generating a second voltage waveform signal that is a basis of the second drive signal; and the second voltage waveform signal connected to the power source. A second current amplifier for amplifying the current of It is clear that a liquid discharge apparatus having 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.
That is, (A) a liquid discharge method using a plurality of elements that perform an operation for discharging a liquid by charging and discharging, and (B) a voltage change pattern determined according to an operation performed by the plurality of elements A first drive signal having a plurality of waveform portions, and a second drive signal having a plurality of waveform portions having a voltage change pattern determined according to the operation to be performed by the plurality of elements, on the first drive signal side A first driving signal in which the voltage change pattern is determined such that a charging period of the element by the Nth waveform section and a charging period of the element by the Nth waveform section on the second driving signal side do not overlap; and Generating the second drive signal simultaneously in a certain period; (C) charging and discharging the plurality of elements by selectively applying a necessary waveform portion to each of the plurality of elements; D) row It will become apparent that a liquid ejecting method can be achieved.

It is also revealed that the following program can be realized.
That is, (A) a program for controlling a liquid ejection apparatus having a plurality of elements that perform an operation for discharging liquid by charging and discharging, and (B) determined according to an operation to be performed by the plurality of elements. A first drive signal having a plurality of waveform portions of the obtained voltage change pattern, and a second drive signal having a plurality of waveform portions of the voltage change pattern determined according to the operation to be performed by the plurality of elements, The voltage change pattern is defined such that the charging period of the element by the Nth waveform portion on the first drive signal side and the charging period of the element by the Nth waveform portion on the second drive signal side do not overlap. Generating a drive signal and a second drive signal simultaneously in a certain period; and (C) selectively applying a necessary waveform portion to each of the plurality of elements to charge / discharge the plurality of elements. Thereby, it is also apparent that can be realized and to perform the (D) to the liquid ejection apparatus.

=== 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 the printer will be described as an example. The printing system is a system having at least a printing apparatus and a printing control apparatus that controls the operation of the printing apparatus.

=== Configuration of Printing System 100 ===
FIG. 1 is a diagram illustrating the configuration of the printing system 100. The illustrated 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 corresponds to a printing apparatus, and prints an image on a medium such as paper, cloth, or film. Note that this medium is an object to which liquid is ejected, and corresponds to, for example, paper S (see FIG. 3). The computer 110 corresponds to a print control apparatus and is connected to the printer 1 so as to be communicable. In order to cause the printer 1 to print an image, the computer 110 outputs print data corresponding to the image to the printer 1. Computer programs such as application programs and printer drivers are installed in the computer 110. The display device 120 has a display. The input device 130 is a device for inputting information such as a keyboard and a mouse. The recording / reproducing device 140 is a flexible disk drive device or the like.

=== Computer 110 ===
<Configuration of Computer 110>
FIG. 2 is a block diagram illustrating configurations of the computer 110 and the printer 1. The computer 110 includes a recording / reproducing device 140 and a host-side controller 111. The recording / reproducing apparatus 140 is communicably connected to the host-side controller 111. The host-side controller 111 performs various controls in the computer 110, and the display device 120 and the input device 130 are also connected to be communicable. The host 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 for securing an area for storing a computer program used by the CPU 113, a work area, and the like. 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 the present embodiment is composed of dot gradation data indicating the size of dots. The size of the dot is determined by the amount of ink (a kind of liquid) to be ejected. For this reason, the dot formation data SI corresponds to ejection amount information indicating the amount of ejected ink.

  The dot formation data SI in the printing system 100 is composed of 3-bit data. For example, the dot formation data SI corresponds to data [000] corresponding to no dot (no ink ejection), data [001] corresponding to the formation of the first small dot, and formation of the second small dot. Data [100], data [010] corresponding to the formation of the first medium dot, data [101] regarding the formation of the second medium dot, and data [011] corresponding to the formation of the large dot. Therefore, the printer 1 can form an image with six gradations for one unit area.

=== Printer 1 ===
<About the configuration of the printer 1>
Next, the configuration of the printer 1 will be described. Here, FIG. 3 is a diagram illustrating a configuration of the printer 1 of the present embodiment. In the following description, FIG. 2 is also referred to. As shown in FIG. 2, the printer 1 includes a paper transport mechanism 20, a carriage moving mechanism 30, a head unit 40, a detector group 50, a printer-side controller 60, a drive signal generation circuit 70, and a power supply unit PWS. The head unit 40 has a head controller HC and a head 41. In the printer 1, the control target unit, that is, the paper transport mechanism 20, the carriage moving mechanism 30, the head unit 40 (head controller HC, head 41), and the drive signal generation circuit 70 are controlled by the printer-side controller 60. As a result, the printer-side controller 60 prints an image on the paper S based on the print data received from the computer 110. Each detector in the detector group 50 monitors the status in the printer 1. Each detector outputs the detection result to the printer-side controller 60. Upon receiving the detection results from each detector, the printer-side controller 60 controls the control target unit based on the detection results.

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

<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, the carriage moving mechanism 30 corresponds to a head moving unit that moves the head 41, and the carriage moving direction corresponds to the head moving direction in which the head 41 moves. 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. A drive pulley 34 is attached to the rotation shaft of the carriage motor 31. The drive pulley 34 is disposed on one end side in the carriage movement direction. An idler pulley 35 is disposed on the other end side in the carriage movement direction on the opposite side to the drive pulley 34. The timing belt 33 is connected to the carriage CR and is spanned between a drive pulley 34 and an idler pulley 35. The guide shaft 32 supports the carriage CR in a movable state. The guide shaft 32 is attached along the carriage movement direction. Accordingly, when the carriage motor 31 operates, the carriage CR moves along the guide shaft 32 in the carriage movement direction.

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

<About the head 41>
FIG. 4 is a cross-sectional view of the head 41. The head 41 is a kind of liquid ejection head that ejects ink, which is a kind of liquid. As shown in FIG. 4, the head has a plurality of flow paths corresponding to the nozzles Nz from the common ink chamber 411 to the nozzles Nz through the pressure chambers 412. When the printer 1 is used, this flow path is filled with ink. The volume of the pressure chamber 412 is changed by the operation of the piezo element 413. That is, a part of the pressure chamber 412 is partitioned by the vibration plate 414, and the piezoelectric element 413 is provided on the surface of the vibration plate 414 on the opposite side to the pressure chamber 412.

  A plurality of piezo elements 413 are provided corresponding to each pressure chamber 412. In other words, a plurality of nozzles corresponding to the nozzles Nz are provided. The piezoelectric elements 413 are connected in parallel to the power supply unit PWS. The piezo element 413 has a configuration in which, for example, a piezoelectric body is sandwiched between an upper electrode and a lower electrode (both not shown), and is deformed by applying a potential difference between these electrodes. In this example, when the potential of the upper electrode is raised, the piezoelectric body is charged, and accordingly, the piezo element 413 is bent (that is, deformed) so as to protrude toward the pressure chamber 412 side. In this case, the volume of the pressure chamber 412 is contracted as indicated by a dotted line in FIG. The amount of deformation of the piezo element 413 is related to the degree of charge. That is, the higher the degree of charge, the greater the amount of deflection of the piezo element 413. For this reason, the volume of the pressure chamber 412 contracts. When the piezo element 413 is suddenly deformed so as to contract the pressure chamber 412, the ink in the pressure chamber 412 is pressurized and the ink is ejected from the nozzle Nz. In the present embodiment, the deformation amount of the piezo element 413 is determined by an application portion (waveform portions SS11 to SS23 described later, see FIG. 10) in the drive signal COM. Therefore, it can be said that the piezo element 413 is deformed according to the potential given by the applied drive signal COM.

  As can be seen from the above description, the piezo element 413 is a plurality of elements that operate to discharge ink by charging and discharging, and corresponds to a plurality of elements that contract the volume of the pressure chamber 412 by charging. Since the head 41 uses the piezo element 413, the ink discharge amount can be accurately controlled by charging / discharging by the drive signal COM.

<About nozzle row>
FIG. 5 is a diagram for explaining the nozzle rows Nk to Nm provided in the head 41. As shown in FIG. 5, the plurality of nozzles Nz are grouped for each type of ink to be ejected, and each group configures four nozzle rows. Therefore, it can be said that the plurality of piezo elements 413 included in the head 41 are also divided into a plurality of groups. In the head unit 40, four types of ink can be ejected. Specifically, the leftmost nozzle row Nk in FIG. 5 ejects black ink. The nozzle row Ny located second from the left ejects yellow ink. Similarly, the third nozzle row Nc from the left ejects cyan ink, and the rightmost nozzle row Nm ejects magenta ink.

  In the present embodiment, one nozzle row is composed of 96 to 180 nozzles arranged at a predetermined interval in a predetermined direction. Four nozzle rows are provided in the intersecting direction orthogonal to the predetermined direction. Note that the plurality of nozzles Nz belonging to one nozzle row are arranged in the transport direction of the paper S in a state where the head unit 40 is attached to the carriage CR. Accordingly, the nozzle rows Nk to Nm are arranged in the carriage movement direction.

<Regarding the detector group 50>
The detector group 50 is for monitoring the status of the printer 1. The detector group 50 includes, for example, a linear encoder 51 shown in FIG. The linear encoder 51 is for detecting the position of the carriage CR (head 41) in the carriage movement direction. In addition, the detector group 50 includes a rotary encoder for detecting the rotation amount of the transport roller 22 and a paper detector for detecting the presence or absence of the paper S (none of which are shown).

<About the printer-side controller 60>
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.

  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. 10). 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 pulses and change pulses correspond to timing pulses for defining the timing at which the drive signals COM_A and COM_B are applied to the piezo element 413. It can be said that the timing pulse defines the generation start timing of the waveform sections SS11 to SS23 included in the drive signals COM_A and COM_B.

  The control signal for generating the drive signal COM is also called a DAC value and corresponds to waveform information for determining the waveform of the drive signal COM.

  The printer-side controller 60 that performs such an operation constitutes a charge / discharge control unit for charging / discharging the piezo element 413 together with the head control unit HC and the drive signal generation circuit 70.

<About the drive signal generation circuit 70>
FIG. 6 is a block diagram for explaining the configuration of the drive signal generation circuit 70. The drive signal generation circuit 70 generates a drive signal COM that is commonly used for each piezo element 413. The drive signal generation circuit 70 corresponds to the drive signal generation unit and constitutes a part of the charge / discharge control unit. The drive signal generation circuit 70 simultaneously generates a plurality of types of drive signals COM over a certain period. In the present embodiment, the first drive signal COM_A and the second drive signal COM_B are generated simultaneously over the printing period T. This printing period T is a period corresponding to the unit area described above. The drive signal generation circuit 70 includes a first drive signal generation unit 70A that generates the first drive signal COM_A and a second drive signal generation unit 70B that generates the second drive signal COM_B.

  The first drive signal generation unit 70A includes a first waveform generation circuit 71A and a first current amplification circuit 72A. 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 generates a first voltage waveform signal COM_A ′ having a voltage waveform that is a basis of the first drive signal COM_A based on the first DAC value (first waveform information). The first waveform generation circuit 71A, for example, a digital-to-analog conversion circuit that outputs an analog signal having a voltage corresponding to the first DAC value, amplifies the voltage of the analog signal output from the digital-to-analog conversion circuit, and outputs the first voltage waveform signal And a voltage amplification circuit that outputs the signal as COM_A ′. The second waveform generation circuit 71B generates a second voltage waveform signal COM_B ′ having a voltage waveform that is the basis of the second drive signal COM_B based on the second DAC value (second waveform information). Similarly to the first waveform generation circuit 71A, for example, the second waveform generation circuit also outputs a digital-analog conversion circuit that outputs an analog signal having a voltage corresponding to the second DAC value, and a voltage of the analog signal output from the digital-analog conversion circuit. And a voltage amplification circuit that outputs the second voltage waveform signal COM_B ′.

  The first current amplification circuit 72A amplifies the current of the first voltage waveform signal COM_A ′ and outputs it as the first drive signal COM_A. As shown in FIG. 8, in the present embodiment, the first current amplification circuit 72A is configured by a pair of transistors connected in a complementary manner. That is, the first current amplifying circuit 72A includes 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 (when the piezo element 413 is charged). The NPN transistor Tr1 has a collector connected to the power supply unit PWS 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 (when the piezo element 413 is discharged). 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 is controlled by the first voltage waveform signal COM_A ′ output from the first waveform generation circuit 71A. Accordingly, the first drive signal COM_A output from the first current amplification circuit 72A has a voltage waveform that follows the first voltage waveform signal COM_A ′.

  The second current amplification circuit 72B amplifies the current of the second voltage waveform signal COM_B ′ and outputs it as the second drive signal COM_B. As shown in FIG. 8, the second current amplifying circuit 72B is also composed of a complementary pair of transistors (NPN type transistor Tr1, PNP type transistor Tr2), like the first current amplifying circuit 72A. Yes. The operation of the second current amplification circuit 72B is controlled by the second voltage waveform signal COM_B ′ output from the second waveform generation circuit 71B. Therefore, the second drive signal COM_B output from the second current amplification circuit 72B has a voltage waveform that follows the second voltage waveform signal COM_B ′.

  As described above, the drive signal generation circuit 70 of the present embodiment includes the first drive signal generation unit 70A including the first waveform generation circuit 71A and the first current amplification circuit 72A, the second waveform generation circuit 71B, and the second current amplification. And the second drive signal generator 70B having the circuit 72B, the first drive signal COM_A and the second drive having a desired voltage waveform and sufficient current capacity to operate the plurality of piezo elements 413. A signal COM_B can be generated.

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

  The first drive signal COM_A includes a waveform section SS11 generated in the period T1, a waveform section SS12 generated in the period T2, and a waveform section SS13 generated in the period T3. Each waveform section SS11 to SS13 has a drive pulse for causing the piezo element 413 to perform a predetermined operation. That is, the waveform section SS11 has a first drive pulse PS1, and the waveform section SS12 has a second drive pulse PS2. The waveform section SS13 has a third drive pulse PS3. The second drive signal COM_B has a waveform section SS21 generated in the period T1, a waveform section SS22 generated in the period T2, and a waveform section SS23 generated in the period T3. Each waveform section SS21 to SS23 also has a drive pulse for causing the piezo element 413 to perform a predetermined operation. That is, the waveform section SS21 has a fourth drive pulse PS4, and the waveform section SS22 has a fifth drive pulse PS5. The waveform section SS23 has a sixth drive pulse PS6.

  These drive pulses PS1 to PS6 correspond to ejection pulses that cause the piezo element 413 to perform an ejection operation for ejecting ink from the nozzles Nz. These drive signals COM_A and COM_B will be described in detail later.

<About power supply unit PWS>
The power supply unit PWS generates an operation power source for operating each unit of the printer 1 from a commercial power source. There are several types of power supplies for operation. For example, a logic power source (for example, DC 3.3V) for operating the CPU 62, the memory 63, etc., a power source (for example, DC 5V) for operating each detector constituting the detector group 50, the transport motor 21 and the carriage motor There is a power source (for example, DC 12V) for operating 31 and the like, and a power source (for example, DC 42V) used for generating the drive signals COM_A and COM_B. In this way, in the printer 1, the power supply for operation used for each unit is generated by one power supply unit PWS. For this reason, the plurality of piezo elements 413 belonging to each of the nozzle arrays Nk to Nm are charged by the operating power supply generated by the common power supply unit PWS.

<About the head controller HC>
Next, the head controller HC will be described. FIG. 7 is a diagram for explaining the configuration of the head controller HC. The head controller HC controls ink ejection using six types of dot formation data SI. That is, the head controller HC corresponds to a signal applying unit and constitutes a part of the charge / discharge controller. The head controller HC selectively applies the waveform sections SS11 to SS13 included in the first drive signal COM_A to the piezo element 413 according to the content of the dot formation data SI, and the waveform section included in the second drive signal COM_B. SS21 to SS23 are selectively applied to the piezo element 413 according to the contents of the dot formation data SI. Accordingly, the piezo element 413 discharges ink according to the applied waveform portions SS11 to SS23. In this way, the first drive signal COM_A side waveform portions SS11 to SS13 and the second drive signal COM_B side waveform portions SS21 to SS23 generated within the printing period T are selectively applied to the piezo element 413. Thus, various controls can be performed even in the limited printing period T.

  The head controller HC includes a first shift register 81A, a second shift register 81B, a third shift register 81C, a first latch circuit 82A, a second latch circuit 82B, a third latch circuit 82C, and control logic. 83, a decoder 84, a first switch 85A, and a second switch 85B. In this head control unit HC, each part excluding the control logic 83, that is, each shift register 81A to 81C, latch circuit 82A to 82C, decoder 84, first switch 85A, and second switch 85B are respectively piezo elements 413. Provided for each. Further, the printer 1 of the present embodiment ejects four types of ink. For this reason, the head controller HC has four blocks denoted by reference numeral BL. The control logic 83 is provided for each type of ink to be ejected, that is, for each block BL.

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

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

  The control logic 83 stores switch control information q0 to q5 for the first switch 85A and switch control information q6 to q11 for the second switch 85B. The switch control information q0 to q11 is transmitted from the printer-side controller 60 through the same signal line as the dot formation data SI. For this reason, the control logic 83 has a shift register 83a for switch control information (also referred to as SPSR 83a) and a pattern register 83b for latching the switch control information q0 to q11 set in the SPSR 83a at the timing of the latch pulse. is doing.

  The switch control information q0 to q11 is determined for each gradation, and the first switch operation information SW_A for operating the first switch 85A and the second switch operation information for operating the second switch 85B. This is information that is the basis of SW_B. As the switch control information q0 to q5 for the first switch 85A, switch control information q0 corresponding to dot non-formation (dot formation data SI [000]) and first small dot formation (dot formation data SI [001] ], The switch control information q1 corresponding to the formation of the second small dot (dot formation data SI [100]), and the formation of the first medium dot (dot formation data SI [010]). , Switch control information q4 corresponding to the second medium dot formation (dot formation data SI [101]), and switch corresponding to the large dot formation (dot formation data SI [011]). Control information q5 is prepared. The switch control information q6 to q11 for the second switch 85B includes switch control information q6 corresponding to the non-formation of dots, switch control information q7 corresponding to the formation of the first small dots, and the second small dots. Switch control information q8 corresponding to the formation, switch control information q9 corresponding to the formation of the first medium dot, switch control information q10 corresponding to the formation of the second medium dot, and switch control information corresponding to the formation of the large dot q11 is prepared.

  The switch logic information q0 to q11 is output from the control logic 83 (pattern register 83b). The contents of the switch control information q0 to q11 are the timing specified by the latch pulse of the latch signal LAT, the timing specified by the first change pulse of the first change signal CH_A, and the second of the second change signal CH_B. It is updated at the timing specified by the change pulse. The specific contents of the switch control information q0 to q11 will be described later.

  The decoder 84 selects the switch control information q0 to q11 output from the control logic 83 according to the dot formation data SI latched by the latch circuit 82, and selects the selected switch control information from the first switch 85A and the second switch 85A. Output to each of the switches 85B. The switch control information selected for the first switch 85A is the first switch operation information SW_A, and the switch control information selected for the second switch 85B is the second switch operation information SW_B.

  The first switch 85A controls application of the first drive signal COM_A to the piezo element 413. For example, the first drive signal COM_A is applied to the piezo element 413 over a period in which the first switch operation information SW_A is data [1]. On the other hand, the first switch 85A does not apply the first drive signal COM_A to the piezo element 413 in the case of data [0]. The second switch 85B controls application of the second drive signal COM_B to the piezo element 413. For example, the second drive signal COM_A is applied to the piezo element 413 over the period when the second switch operation information SW_B is data [1]. The second switch 85B also does not apply the first drive signal COM_A to the piezo element 413 in the case of data [0].

<Dummy load>
The drive signal generation circuit 70 described above uses a transistor pair for current amplification. For this reason, oscillation may occur due to an inductance component or a capacitor component existing in the circuit. Since unnecessary oscillation is not preferable, the printer 1 is provided with a dummy load to prevent unnecessary oscillation. Hereinafter, the dummy load will be described. Here, FIG. 8 is a diagram showing a simplified path for applying the drive signal COM to the piezo element 413.

  As shown in FIG. 8, the dummy load includes a first dummy load DLA for the first drive signal COM_A and a second dummy load DLB for the second drive signal COM_B. The first dummy load DLA is connected to a signal line for the first drive signal COM_A provided between the first current amplification circuit 72A and the flexible cable FC. The second dummy load DLB is connected to a signal line for the second drive signal COM_B provided between the second current amplification circuit 72B and the flexible cable FC. These dummy loads DLA and DLB are composed of resistors and capacitors connected in series. That is, the first dummy load DLA is composed of the first dummy resistor DRA and the first dummy capacitor DCA. The first dummy resistor DRA has one end connected to the signal line for the first drive signal COM_A and the other end connected to one end of the first dummy capacitor DCA. The first dummy capacitor DCA has one end connected to the other end of the first dummy resistor DRA and the other end connected to the ground. Similarly, the second dummy load DLB includes a second dummy resistor DRB and a second dummy capacitor DCB. The second dummy resistor DRB has one end connected to the signal line for the second drive signal COM_B and the other end connected to one end of the second dummy capacitor DCB. The second dummy capacitor DCB has one end connected to the other end of the second dummy resistor DRB and the other end connected to the ground. Note that the electrostatic capacitances of the first dummy capacitor DCA and the second dummy capacitor DCB are respectively determined to be capacitors that prevent oscillation. For example, it is set to about 10% to 30% with respect to the combined capacitance of all the piezo elements 413. The first dummy capacitor DCA and the second dummy capacitor DCB are connected in parallel to the plurality of piezo elements 413.

  By providing these dummy loads DLA and DLB, charging and discharging of the dummy capacitors DCA and DCB are performed even when charging and discharging of all the piezo elements 413 are not performed. That is, the first dummy capacitor DCA (first capacitor) is charged / discharged according to the first drive signal COM_A, and the second dummy capacitor DCB (second capacitor) is charged / discharged according to the second drive signal COM_B. This stabilizes the operation of the circuit and prevents unnecessary oscillation.

=== Printing operation ===
<About printing operation>
Next, a printing operation performed by the printer 1 for printing on the paper S will be described. Here, FIG. 9 is a flowchart for explaining the printing operation of the printer 1. As shown in FIG. 9, in the printer 1, as a series of printing operations, a printing command receiving operation (S10), a paper feeding operation (S20), a dot forming operation (S30), a conveying operation (S40), and a paper discharge determination ( S50), a paper discharge operation (S60), and a print end determination (S70) are performed. This printing operation is performed by the CPU 62 included in the printer-side controller 60. That is, the CPU 62 operates according to the computer program stored in the memory 63 and executes these operations. Therefore, this computer program has a code for executing each operation.

  The print command reception operation is an operation of receiving a print command transmitted from the computer 110. This command is included in print data transmitted from the computer 110, for example. The paper feeding operation is an operation of moving the paper S to be printed and positioning it at the print start position. The dot formation operation is an operation in which dots are formed on the paper S by intermittently ejecting ink from the head 41 moving in the carriage movement direction. In this dot forming operation, the printer-side controller 60 drives the carriage motor 31 to move the carriage CR in the carriage movement direction. Further, while the carriage CR is moving, ink is ejected from the head 41 (nozzle Nz) based on the dot formation data SI. Then, when the ink ejected from the head 41 lands, dots are formed in the unit area of the paper S. The transport operation is an operation of moving the paper S relative to the head 41 along the transport direction. By this transport operation, the head 41 can form dots at positions different from the positions of the dots formed by the previous dot formation operation. The paper discharge determination is a process for determining whether or not to discharge the paper S being printed. This determination is made based on the presence or absence of print data, for example. The print end determination is a determination as to whether or not to continue printing.

=== Details of Dot Forming Operation ===
<About the amount of current when charging the piezo element 413>
The first drive signal COM_A has three waveform parts SS11 to SS13 in the printing period T, and the second drive signal COM_B has three waveform parts SS21 to SS23 in the printing period T. Then, a necessary waveform portion is selected according to the content of the dot formation data SI and applied to the piezo element 413. The piezoelectric element 413 is charged / discharged according to the applied voltage change pattern of the waveform portion. Here, a power source for charging each piezo element 413 is generated by a common power supply unit PWS. For this reason, if the charging period of the piezo element 413 by each waveform unit included in the first drive signal COM_A and the charging period of the piezo element 413 by each waveform unit included in the second drive signal COM_B overlap, the power supply unit PWS The amount of current flowing to each piezo element 413 increases. Since the power consumption increases depending on the amount of current, the power consumption increases as the amount of current increases.

  In particular, since the printer 1 includes the two dummy loads DLA and DLB that are charged and discharged by the drive signals COM_A and COM_B regardless of the piezo element 413, if the drive signals COM_A and COM_B are generated, Electric power is consumed even when the piezo element 413 is not charged or discharged. Therefore, if the charging period by each waveform unit on the first drive signal COM_A side overlaps with the charging period by each waveform unit on the second drive signal COM_B side, a large amount of power is consumed.

  In view of such circumstances, in this printer 1, the charging period of the piezo element 413 by the Nth (N is a natural number) waveform portion on the first drive signal COM_A side and the Nth waveform on the second drive signal side COM_B side are considered. The voltage change pattern of the first drive signal COM_A and the voltage change pattern of the second drive signal COM_B are determined so that the charging period of the piezoelectric element 413 by the unit does not overlap. With this configuration, the maximum value of the current flowing from the power supply unit PWS to the piezo element 413 during charging can be made lower than that in the past, and power consumption can be suppressed. Details will be described below.

<About the generated drive signal and the application operation of each waveform section>
FIG. 10 is a diagram illustrating the first drive signal COM_A, the second drive signal COM_B, the latch signal LAT, the first change signal CH_A, and the second change signal CH_B generated by the dot formation operation. FIG. 11 is a diagram illustrating specific contents of the switch operation information q0 to q11.

  As shown in FIG. 10, the first drive signal COM_A includes a waveform section SS11 generated in the first period T1 in the printing period T (repetition period), a waveform section SS12 generated in the second period T2, and 3 And a waveform portion SS13 generated in the th period T3. The waveform section SS11 has a first drive pulse PS1. The waveform section SS12 has a second drive pulse PS2, and the waveform section SS13 has a third drive pulse PS3. The second drive signal COM_B includes a waveform section SS21 generated in the period T1, a waveform section SS22 generated in the period T2, and a waveform section SS23 generated in the period T3. The waveform section SS21 has a fourth drive pulse PS4. The waveform section SS22 has a fifth drive pulse PS5, and the waveform section SS23 has a sixth drive pulse PS6.

  The voltage waveform of the drive pulses PS1 to PS6 included in each waveform section SS11 to SS23 has a change pattern determined according to the operation that the piezo element 413 performs. The start voltage and the end voltage of these drive pulses PS1 to PS6 are the same, and these voltages are reference voltages. Accordingly, each of the waveform sections SS11 to SS23 having these drive pulses PS1 to PS6 starts from the reference voltage and returns to the reference voltage after undergoing a voltage change of a pattern determined according to the operation to be performed by the piezo element 413. It can be said that.

  As described above, the piezo element 413 changes the volume of the pressure chamber 412 according to the charge / discharge state. For example, the volume of the pressure chamber 412 at the reference voltage is set as the reference volume. When a voltage portion higher than the reference voltage in a certain drive pulse is applied to the piezo element 413, the piezo element 413 is deformed so as to protrude toward the pressure chamber 412 side. Along with this, the pressure chamber 412 contracts from the reference volume. Conversely, when a voltage portion lower than the reference voltage in a certain drive pulse is applied to the piezo element 413, the piezo element 413 is deformed so that the degree of convexity is reduced. Along with this, the pressure chamber 412 expands more than the reference volume.

  The drive pulses PS1 to PS6 are all ejection pulses for ejecting ink. Of these drive pulses PS1 to PS6, the drive pulses PS1 to PS3 all have the same voltage waveform (voltage change pattern), and the drive pulses PS4 to PS6 all have the same voltage waveform. The degree of deformation of the piezo element 413 is determined by the state of charge of the piezo element 413, and the state of charge of the piezo element 413 is determined by the voltage change pattern of the applied waveform portion. Therefore, it can be said that the drive pulses PS1 to PS3 are for causing the piezo element 413 to perform the same operation, and the drive pulses PS4 to PS6 are for causing the piezo element 413 to perform the same operation. With respect to these drive pulses PS1 to PS6, in the present embodiment, when one of the drive pulses PS1 to PS3 is applied to the piezo element 413, about 2.5 pL of ink is ejected from the nozzle Nz. When one of the drive pulses PS4 to PS7 is applied to the piezo element 413, about 7 pL of ink is ejected from the nozzle Nz. That is, regarding these waveform portions SS11 to SS23, it can be said that the Nth waveform portion on the first drive signal COM_A side causes the piezo element 413 to operate differently from the Nth waveform portion on the second drive signal COM_B side. Thereby, it is possible to cause the piezo element 413 to perform various operations in the limited printing period T.

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

  In the case of dot formation data SI without dots, the corresponding switch operation information q0 is data [000], and the switch operation information q6 is also data [000]. Thereby, none of the waveform portions SS11 to SS13 on the first drive signal COM_A side and the waveform portions SS21 to SS23 on the second drive signal COM_B side are applied to the piezo element 413. As a result, no ink is ejected from the nozzle Nz. In the case of the dot formation data SI of the first small dot, the corresponding switch operation information q1 is data [010], and the switch operation information q7 is data [000]. Accordingly, the waveform portion SS12 on the first drive signal COM_A side is applied to the piezo element 413 in the period T2. Then, about 2.5 pL of ink is ejected from the nozzle Nz by the second drive pulse PS2 included in the waveform section SS12. In the case of the second small dot dot formation data SI, the corresponding switch operation information q2 is data [101], and the switch operation information q8 is data [000]. Accordingly, the waveform portion SS11 on the first drive signal COM_A side is applied to the piezoelectric element 413 in the period T1, and the waveform portion SS13 on the first drive signal COM_A side is applied to the piezoelectric element 413 in the period T3. Then, a total of about 5 pL of ink is ejected from the nozzle Nz by the first drive pulse PS1 included in the waveform section SS11 and the third drive pulse PS3 included in the waveform section SS13.

  In the case of the dot formation data SI for the first medium dot, the corresponding switch operation information q3 is data [000], and the switch operation information q9 is data [010]. As a result, the waveform portion SS22 on the second drive signal COM_B side is applied to the piezo element 413 in the period T2. Then, about 7 pL of ink is ejected from the nozzle Nz by the fifth drive pulse PS5 included in the waveform section SS22. The switch operation information q4 corresponding to the dot formation data SI for the second medium dot is data [000], and the switch operation information q10 is data [101]. Thereby, the waveform portion SS21 on the second drive signal COM_B side is applied to the piezoelectric element 413 in the period T1, and the waveform portion SS23 on the second drive signal COM_B side is applied to the piezoelectric element 413 in the period T3. Then, a total of about 14 pL of ink is ejected from the nozzles Nz by the fourth drive pulse PS4 included in the waveform section SS21 and the sixth drive pulse PS6 included in the waveform section SS23. The switch operation information q5 corresponding to the large dot formation data SI is data [000], and the switch operation information q11 is data [111]. Accordingly, the waveform portion SS21 on the second drive signal COM_B side in the period T1, the waveform portion SS22 on the second drive signal COM_B side in the period T2, and the waveform portion SS23 on the second drive signal COM_B side in the period T3. Each is applied to the piezo element 413. Then, a total of about 21 pL of ink is ejected from the nozzles Nz by the fourth drive pulse PS4 included in the waveform section SS21, the fifth drive pulse PS5 included in the waveform section SS22, and the sixth drive pulse PS6 included in the waveform section SS23. The

=== Charging by the Nth Waveform Part ===
Next, charging of each piezo element 413 and each of the dummy capacitors DCA and DCB by the Nth waveform portion on the first drive signal COM_A side, and each piezo element 413 by the Nth waveform portion on the second drive signal COM_B side, The charging of the dummy capacitors DCA and DCB will be described. Here, FIG. 12A is a diagram illustrating the relationship between the voltage waveform and the current waveform for the waveform section SS11 and the waveform section SS21. That is, it is a diagram for explaining the relationship between the first waveform portions. FIG. 12B is a diagram schematically illustrating the amount of current flowing from the power supply unit PWS in the period T1.

<Regarding the voltage waveform of the waveform section SS11>
First, the waveform section SS11 will be described. The waveform section SS11 has a first constant voltage section HS1, a second constant voltage section HS2, and a first drive pulse PS1. The first constant voltage unit HS1 is a constant part in the reference voltage VM generated from timing t0 to t2. The second constant voltage unit HS2 is a constant part in the reference voltage VM generated from timing t12 to t13. During the period in which the constant voltage portions HS1 and HS2 are applied, the piezo element 413 bends to a degree corresponding to the reference voltage VM, and maintains the volume of the pressure chamber 412 at the reference volume.

  The first drive pulse PS1 is composed of parts a1 to a5. The portion a1 is generated from timing t2 to t5, and drops the voltage from the reference voltage VM to the first lowest voltage VL1 with a certain degree (also referred to as a slope θ1 for convenience). The portion a2 is generated from the timing t5 to t7, and is constant at the first lowest voltage VL1. The portion a3 is generated from the timing t7 to the timing t9 and increases the voltage from the first lowest voltage VL1 to the first highest voltage VH1 with a certain degree (also referred to as a gradient θ2 for convenience). The portion a4 is generated from the timing t9 to the time t10, and is constant at the first highest voltage VH1. The portion a5 is generated from the timing t10 to t12, and drops the voltage at a certain degree (also referred to as a slope θ3 for convenience) from the first highest voltage VH1 to the reference voltage VM. In the first drive pulse PS1, the gradient θ1 is the same as the gradient θ3. In addition, the absolute value of the inclination θ2 is larger than the absolute values of the inclinations θ1 and θ3.

<Operation of Piezoelectric Element 413 by First Drive Pulse PS1>
When such a first drive pulse PS1 is applied, the piezo element 413 operates as follows. First, at the application start time (timing t2) of the portion a1, the piezo element 413 is bent to a degree corresponding to the reference voltage VM, and the pressure chamber 412 has a reference volume. In the period up to the timing t5, the piezo element 413 reduces the degree of bending following the voltage change of the portion a1. As a result, the pressure chamber 412 is gradually expanded. At a timing t5, an expansion state corresponding to the first lowest voltage VL1 is obtained. Next, the part a2 is applied. As a result, the piezoelectric element 413 maintains a bent state until the timing t7, and the expanded state of the pressure chamber 412 is maintained. Next, the part a3 is applied. As a result, during the period up to timing t9, the piezo element 413 increases the degree of bending following the voltage change of the portion a3. Accordingly, the pressure chamber 412 contracts as the degree of bending of the piezo element 413 increases. At timing t9, the pressure chamber 412 is in a contracted state corresponding to the first highest voltage VH1. At this time, the pressure chamber 412 is rapidly contracted in a very short time. Along with this, the ink in the pressure chamber 412 is rapidly pressurized, and the ink is ejected from the nozzle Nz by this pressurization. Next, the part a4 is applied. As a result, the piezoelectric element 413 maintains a bent state until the timing t10, and the contracted state of the pressure chamber 412 is maintained. Finally, part a5 is applied. As a result, during the period up to timing t12, the piezo element 413 reduces the degree of bending following the voltage change of the portion a5. As a result, the pressure chamber 412 is gradually expanded and becomes the reference volume at the timing t12. Due to the expansion of the pressure chamber 412, the ink pressure fluctuation after ink ejection is alleviated.

<About the current flowing by the first drive pulse PS1>
As the drive pulse PS1 is applied, a current flows from the power supply unit PWS to the piezo element 413, or a current flows from the piezo element 413 to the ground. Regardless of the piezo element 413, a current flows through the dummy capacitors DCA and DCB. Hereinafter, this current will be described. For convenience, in the following description, the current during charging flowing from the power supply unit PWS to each piezo element 413 and each dummy capacitor DCA, DCB is represented as a positive current, and flows from each piezo element 413 or each dummy capacitor DCA, DCB to the ground. The current during discharge is expressed as a negative current. Further, it is assumed that the current corresponding to the gradient θ2 is 1i, and the current corresponding to the gradients θ1 and θ3 is −0.5i.

  During application of the portion a1 (timing t2 to t5), the discharging PNP transistor Tr2 included in the first current amplification circuit 72A is turned on, and the piezo element 413 and the ground are connected through the PNP transistor Tr2. As a result, as shown in FIG. 8, a current I2A of −0.5i corresponding to the inclination θ1 flows from the piezo element 413 or the first dummy capacitor DCA toward the ground.

  Next, the portion a2 is applied, but no current flows because the portion a2 has a constant voltage. During application of the portion a3 (timing t7 to t9), the charging NPN transistor Tr1 included in the first current amplification circuit 72A is turned on, and the power supply unit PWS and the piezoelectric element 413 are connected through the NPN transistor Tr1. Connected. As a result, a 1i current I1A corresponding to the inclination θ2 flows from the power supply unit PWS toward the piezo element 413 and the first dummy capacitor DCA.

  Next, the portion a4 is applied, but no current flows because the portion a4 has a constant voltage. During application of the portion a5 (timing t10 to t12), the discharging PNP transistor Tr2 included in the first current amplification circuit 72A is turned on, and a current I2A of −0.5i corresponding to the inclination θ3 is piezo. The current flows from the element 413 and the first dummy capacitor DCA toward the ground.

<About the voltage waveform of the waveform section SS21>
Next, the waveform section SS21 will be described. The basic shape of the waveform section SS21 is the same as that of the waveform section SS11. That is, it has a third constant voltage unit HS3, a fourth constant voltage unit HS4, and a fourth drive pulse PS4. The third constant voltage unit HS3 is a constant part in the reference voltage VM generated from timing t0 to t1. The fourth constant voltage unit HS4 is a constant part of the reference voltage VM generated from timing t11 to t13. During the period in which the constant voltage portions HS1 and HS2 are applied, the piezo element 413 bends to a degree corresponding to the reference voltage VM, and maintains the volume of the pressure chamber 412 at the reference volume.

  The fourth drive pulse PS4 is composed of parts b1 to b5. The portion b1 is generated from the timing t1 to the timing t3, and drops the voltage with a slope θ1 from the reference voltage VM to the first lowest voltage VL1. The portion b2 is generated from timing t3 to t4 and is constant at the second lowest voltage VL2. The second minimum voltage VL2 is set to a value lower than the first minimum voltage VL1 described above. The portion b3 is generated from the timing t4 to the timing t6, and increases the voltage with the slope θ2 from the second lowest voltage VL2 to the second highest voltage VH2. The second highest voltage VH2 is set to a value higher than the first highest voltage VH1 described above. The portion b4 is generated from the timing t6 to the timing t8 and is constant at the second highest voltage VH2. The part b5 is generated from the timing t8 to the time t11, and drops the voltage with the slope θ3 from the second highest voltage VH2 to the reference voltage VM.

<Operation of Piezoelectric Element 413 by Fourth Driving Pulse PS4>
When such a fourth drive pulse PS4 is applied, the piezo element 413 operates as follows. First, the pressure chamber 412 is set to a reference volume at the start of application of the portion a1. In the period up to the timing t3, the piezo element 413 reduces the degree of bending following the voltage change of the portion b1. As a result, the pressure chamber 412 is gradually expanded and enters an expanded state corresponding to the second lowest voltage VL2 at timing t5. Here, the voltage of the portion b1 is lowered with the same inclination θ1 as that of the portion a1. In other words, the discharge rate of the piezo element 413 is the same when the portion a1 is applied and when the portion b1 is applied. For this reason, the deformation speed of the piezo element 413 by the part b1 is the same as the deformation speed of the piezo element 413 by the part a1. Further, since the second lowest voltage VL2 is lower than the first lowest voltage VL1, the volume of the pressure chamber 412 at the end of application of the portion b1 is larger than the volume at the end of application of the portion a1.

  Next, the part b2 is applied. As a result, the piezoelectric element 413 maintains a bent state until the timing t4, and the expanded state of the pressure chamber 412 is maintained. During application of the portion b3, the piezoelectric element 413 increases the degree of bending, and the pressure chamber 412 is contracted. At time t6, the pressure chamber 412 enters a contracted state corresponding to the second highest voltage VH2. At this time, the pressure chamber 412 is rapidly contracted in a very short time. In addition, since the second highest voltage VH2 is higher than the first highest voltage VH1, the volume of the pressure chamber 412 at the end of application of the portion b2 is smaller than that at the end of application of the portion a2. Along with the application of the portion b2, the ink in the pressure chamber 412 is rapidly pressurized, and the ink is ejected from the nozzle Nz by this pressurization. At this time, the contraction amount of the pressure chamber 412 is larger than the contraction amount when the portion a2 is applied. For this reason, the amount of ejected ink is greater than when the first drive pulse PS1 is applied.

  Next, the part b4 is applied. As a result, the piezoelectric element 413 maintains the bent state until the timing t8, and the contracted state of the pressure chamber 412 is maintained. During application of the portion b5, the pressure chamber 412 is gradually expanded, and the pressure fluctuation of the ink after the ink is discharged is alleviated. At time t11, the pressure chamber 412 becomes the reference volume.

<About the current flowing by the fourth drive pulse PS4>
During application of the portion b1 (timing t1 to t3), the discharging PNP transistor Tr2 included in the second current amplification circuit 72B is turned on, and the piezo element 413 and the ground are connected through the PNP transistor Tr2. As a result, as shown in FIG. 8, a current I2B of −0.5i corresponding to the inclination θ1 flows from the piezo element 413 or the second dummy capacitor DCB toward the ground.

  Next, the part b2 is applied, but no current flows because the part b2 has a constant voltage. During application of the portion b3 (timing t4 to t6), the charging NPN transistor Tr1 included in the second current amplifier circuit 72B is turned on, and the power supply unit PWS and the piezoelectric element 413 are connected through the NPN transistor Tr1. Connected. As a result, a 1i current I1B corresponding to the inclination θ2 flows from the power supply unit PWS toward the piezo element 413 and the second dummy capacitor DCB.

  Next, the portion b4 is applied, but no current flows because the portion b4 has a constant voltage. During the application of the portion b5 (timing t8 to t11), the discharging PNP transistor Tr2 included in the second current amplification circuit 72B is turned on, and a current I2B of −0.5i corresponding to the inclination θ3 is piezo. The current flows from the element 413 and the second dummy capacitor DCB toward the ground.

<About the current during charging in the period T1>
As described above, the power supply unit PWS generates a 42V power supply used when charging each piezo element 413. Therefore, even when the piezo element 413 is charged by the waveform parts SS11 to SS13 included in the first drive signal COM_A, and the piezo element 413 is charged by the waveform parts SS21 to SS23 included in the second drive signal COM_B. Current flows from the portion PWS toward the piezo element 413.

  In the relationship between the waveform section SS11 and the waveform section SS21 described above, the charging period of the piezo element 413 by the first drive pulse PS1 is a period from timing t7 to t9, and the current I1A flows to the piezo element 413 during this period. Further, the charging period of the piezo element 413 by the fourth drive pulse PS4 is a period from timing t4 to t6, and the current I1B flows to the piezo element 413 during this period. As shown in FIG. 12B, the charging period A (t7-t9) by the first drive pulse PS1 and the charging period B (t4-t6) by the fourth drive pulse PS4 do not overlap.

In this case, when the effective value in the period T1 is obtained, the following equation (1) is obtained.

<About Comparative Example>
Next, a comparative example will be described. FIG. 13A is a diagram illustrating the relationship between the voltage waveform and the current waveform for the comparative example. FIG. 13B is a diagram schematically illustrating the amount of current flowing from the power supply unit PWS in the comparative example.

  In this comparative example, the first driving pulse PS1 ′ for comparison having the same voltage waveform as the first driving pulse PS1 and the first driving pulse PS4 ′ for comparison having the same voltage waveform as the fourth driving pulse PS4 are used. In this comparative example, the generation timings of the drive pulses PS1 ′ and PS4 ′ are different from the generation timings of the drive pulses PS1 and PS4 of the first embodiment. Briefly described, each of the drive pulses PS1 ′ and PS4 ′ is generated from timing t1 ′ to t10 ′. As a result, the charging portion a3 ′ in the first comparison driving pulse PS1 ′ is generated over the period from the timing t5 ′ to t6 ′ (charging period A), and the charging portion in the fourth comparison driving pulse PS4 ′. The part b3 ′ is generated over a period (charging period B) from timing t4 ′ to t7 ′. The intermediate timing in the charging period A and the intermediate timing in the charging period B coincide with each other.

  That is, in this comparative example, the charging period B by the fourth drive pulse PS4 and the charging period A by the first drive pulse PS1 overlap. Accordingly, in the charging period A, a current of 2i flows from the power supply unit PWS toward the piezo element 413 and the dummy capacitors DCA and DCB. In addition, the inclination θ2 of the part a3 ′ and the part b3 ′ is the same, and the change width of the voltage is larger in the part b3 ′. Therefore, the charging period B is longer than the charging period A. Since the intermediate timings of the charging period A and the charging period B coincide with each other, the period during which the piezo element 413 and the like are charged only by the portion b3 ′ is the front side of the charging period A (timing t4 ′ to t5 ′). At each of the rear sides (timing t6 ′ to t7 ′), (B−A) / 2 is obtained.

In this case, when the effective value in the period T1 is obtained, the following equation (2) is obtained.

<Summary>
From the equations (1) and (2), it can be seen that the effective values are different even for the drive pulses PS1, PS1 ′ and the drive pulses PS4, PS4 ′ having the same voltage waveform. That is, the effective value of the first embodiment is √ [(A + B) / T1] × i, and the effective value of the comparative example is √ [(3A + B) / T1] × i. Since the effective value of this embodiment is smaller than that of the comparative example, it can be said that the power consumption can be suppressed by that amount. In other words, the power consumption can be suppressed because the maximum value of the current flowing to the piezo element 413 is reduced with the application of the waveform portion.

  By the way, although the above demonstrated waveform part SS11 and waveform part SS21 which are the 1st waveform parts, it is the same also about another waveform part. That is, the waveform portion SS12 (second drive pulse PS2) and the waveform portion SS22 (fifth drive pulse PS5) as the second waveform portion, and the waveform portion SS13 (third drive pulse PS3) as the third waveform portion. The same applies to the waveform section SS23 (sixth drive pulse PS6).

  Note that which piezo element 413 is to be charged and discharged in the printing operation is determined by the print data. As the number of piezo elements 413 to be charged / discharged increases, the amount of current flowing from the power supply unit PWS to the piezo elements 413 increases and the power consumption increases.

  By configuring as in the present embodiment, the power consumption when the same print data is used can be made lower than in the comparative example.

  Further, the printer 1 of the present embodiment has dummy loads DLA and DLB for preventing oscillation. The first dummy load DLA includes a first dummy capacitor DCA that is charged / discharged by the first drive signal COM_A, and the second dummy load DLB is a second dummy capacitor DCB that is charged / discharged by the second drive signal COM_B. have. These dummy loads DLA and DLB are charged and discharged regardless of the piezo element 413. For example, even if all the piezo elements 413 are charged / discharged, they are charged / discharged, and even if all the piezo elements 413 are not charged / discharged, they are charged / discharged. Therefore, in the printer 1 having such dummy loads DLA and DLB, the maximum value of the current flowing from the power supply unit PWS to the dummy capacitors DCA and DCB can be minimized. As a result, power consumption can be suppressed while suppressing unnecessary oscillation of the circuit.

  The piezo element 413 included in the head 41 operates to contract the pressure chamber 412 by charging. In this configuration, since the pressure chamber 412 needs to be rapidly contracted when ink is ejected, the piezo element 413 is rapidly charged. In the printer 1 having such a piezo element 413, since the charging period of the piezo element 413 by the waveform portions SS11 to SS23 is shifted, the power consumption can be effectively suppressed.

=== Second Embodiment ===
In the first embodiment described above, the generation period of the Nth waveform part (SS11 to SS13) on the first drive signal COM_A side and the generation period of the Nth waveform part (SS21 to SS23) on the second drive signal COM_B side are described. Was the same. Further, the waveform parts SS11 to SS13 on the first drive signal COM_A side have the same voltage waveform, and the waveform parts SS21 to SS23 on the second drive signal COM_B side have the same voltage waveform. The second embodiment is different from the first embodiment in these points. In other words, in the second embodiment, the piezo element 413 is operated by the Nth waveform portion on the second drive signal COM_B side by the Nth waveform portion on the first drive signal COM_A side. The generation period of the Nth waveform part on the first drive signal COM_A side is different from the generation period of the Nth waveform part on the second drive signal COM_B side.

  Hereinafter, a second embodiment will be described. FIG. 14 is a diagram illustrating the first drive signal COM_A and the second drive signal COM_B generated in the second embodiment. FIG. 15 is a diagram for explaining current when the first drive signal COM_A and the second drive signal COM_B are applied to the piezo element 413 and the like. Since the configuration of the printer 1 is the same as that of the first embodiment described above, description thereof is omitted.

<Regarding Generated Drive Signals COM_A and COM_B>
As shown in FIG. 14, in the second embodiment, the drive signal generation circuit 70 generates a first drive signal COM_A having three waveform portions SS31 to SS33 and a second drive signal COM_B having three waveform portions SS41 to SS43. They are generated simultaneously in the printing period T. The waveform section SS31 is generated in the period T11 and has the first drive pulse PS11. The waveform section SS32 is generated in the period T12, and has the second drive pulse PS12. The waveform section SS33 is generated in the period T13 and has a third drive pulse PS13. The waveform section SS41 is generated in the period T21 and has a fourth drive pulse PS14. The waveform section SS42 is generated in the period T22 and has a fifth drive pulse PS15. The waveform section SS43 is generated in the period T23 and has a sixth drive pulse PS16.

  Among these drive pulses PS11 to PS16, the fourth drive pulse PS14 is a fine vibration pulse. When the fourth drive pulse PS14 is applied to the piezo element 413, a pressure change that does not eject ink occurs in the ink in the pressure chamber 412. Thereby, the meniscus (the free surface of the ink exposed from the nozzle Nz) slightly vibrates, and the ink near the nozzle Nz is agitated. The fifth drive pulse PS15 is a first small dot pulse. When the fifth drive pulse PS15 is applied to the piezo element 413, an amount of ink suitable for forming the first small dot is ejected from the nozzle Nz. In this example, about 1.5 pL of ink is ejected. The third drive pulse PS13 is a second small dot pulse. When the third drive pulse PS15 is applied to the piezo element 413, an amount of ink suitable for forming the second small dot is ejected from the nozzle Nz. In this example, about 3 pL of ink is ejected. The first drive pulse PS11, the second drive pulse PS12, and the sixth drive pulse PS16 are all medium dot pulses. When any one of these drive pulses PS11, PS12, and PS16 is applied to the piezo element 413, an amount of ink suitable for the first medium dot is ejected from the nozzle Nz. In this example, about 7 pL of ink is ejected. When two drive pulses are applied to the piezo element 413, an amount of ink suitable for the second medium dot is ejected from the nozzle Nz. In this example, about 14 pL of ink is ejected. Further, when three drive pulses are applied to the piezo element 413, an amount of ink suitable for a large dot is ejected from the nozzle Nz. In this example, about 21 pL of ink is ejected.

  The generation period of these drive pulses PS11 to PS16 is determined according to the operation to be performed by the piezo element 413. For this reason, the generation period of the waveform portion having these drive pulses PS11 to PS16 is also determined according to the operation to be performed by the piezo element 413. In the second embodiment, the generation period of the waveform portion SS31 that is the first waveform portion in the first drive signal COM_A is T11, whereas the generation period of the waveform portion SS41 that is the first waveform portion in the second drive signal COM_B. The generation period is T21. Here, the fourth drive pulse PS14 included in the waveform section SS41 only needs to vibrate the meniscus. For this reason, the generation period of the fourth drive pulse PS14 is shorter than the generation period of other drive pulses for discharging ink. Along with this, the generation period T21 of the waveform section SS41 is shorter than the generation period T11 of the waveform section SS31. In addition, the generation period of the waveform part SS32 which is the second waveform part in the first drive signal COM_A is T12, whereas the generation period of the waveform part SS42 which is the second waveform part in the second drive signal COM_B is T22. It has become. Here, the fifth drive pulse PS15 included in the waveform section SS42 controls the meniscus in a complicated manner in order to eject an extremely small amount of ink. For this reason, the generation period of the fifth drive pulse PS15 is longer than the generation period of the second drive pulse PS12. Along with this, the generation period T22 of the waveform section SS42 is longer than the generation period T12 of the waveform section SS32. Furthermore, while the generation period of the waveform section SS33 is T13, the generation period of the waveform section SS43 is T23. Here, the third drive pulse PS13 included in the waveform section SS33 has substantially the same generation period as the sixth drive pulse PS16 included in the waveform section SS43, but the timing of the change pulse on the first change signal CH_A side and the second change pulse In order to shift the timing of the change pulse on the signal CH_B side, the generation period T13 of the waveform section SS23 is longer than the generation period T23 of the waveform section SS43.

  As described above, the first drive signal COM_A and the second drive signal COM_B of the present embodiment are related to the Nth waveform portion on the first drive signal COM_A side and the Nth waveform portion on the second drive signal COM_B side. The operation performed by the element 413 and the generation period are different from each other. For this reason, even during the limited printing period T, it is possible to finely control the amount of ink discharged or to perform movement such as fine vibration. Further, the degree of freedom in time for the voltage waveform of each waveform section SS31 to SS43 is increased, and the operation to be performed by the piezo element 413 can be optimized.

<About the current during charging>
Next, a current flowing toward the piezo element 413 and the like during charging will be described. Also in this embodiment, the charging period by the waveform parts SS31 to SS33 on the first drive signal COM_A side and the charging period by the waveform parts SS41 to SS43 on the second drive signal COM_B side are determined so as not to overlap each other. Yes. For example, the charging period Tb of the waveform section SS31 (first driving pulse PS11) is determined so as not to overlap the charging period Ta of the waveform section SS41 (fourth driving pulse PS14). Similarly, the charging period Td of the waveform section SS32 (second drive pulse PS12) is determined so as not to overlap the charging periods Tc and Te of the waveform section SS42 (fifth drive pulse PS15), and the waveform section SS33 (second waveform) The charging periods Tf and Th of the third driving pulse PS13) are determined so as not to overlap with the charging period Tg of the waveform section SS43 (sixth driving pulse PS16).
As a result, as in the first embodiment described above, the maximum value of current during charging can be suppressed, and power consumption can be suppressed.

=== Third Embodiment ===
In each of the embodiments described above, the waveform portion on the first drive signal side and the waveform portion on the second drive signal COM_B side can be selectively applied to one piezo element 413. That is, a necessary part can be applied to one piezo element 413 from a plurality of drive signals. The third embodiment is different from each embodiment in this point. Briefly, a waveform portion possessed by a certain drive signal is applied to a piezo element 413 belonging to a certain nozzle row, and a waveform portion possessed by another drive signal is applied to a piezo element 413 belonging to another nozzle row. It is trying to apply.

  Hereinafter, the third embodiment will be described. FIG. 16 is a diagram for explaining the configuration of the third embodiment. FIG. 17A is a diagram for explaining a drive signal COM (BY) for black ink and yellow ink. FIG. 17B is a diagram illustrating drive signals COM (CM) for cyan ink and magenta ink. FIG. 17C is a diagram schematically illustrating a current when the piezo element 413 is charged.

<About the configuration of the printer 1>
As shown in FIG. 16, in the printer 1 of the third embodiment, the drive signal generation circuit 70 is a first waveform generation circuit 71 (for generating a first drive signal COM (BY) for black ink and yellow ink). BY) and first current amplification circuit 72 (BY), and second waveform generation circuit 71 (CM) and second current amplification circuit 72 for generating a second drive signal COM (CM) for cyan ink and magenta ink. (CM).

  The first waveform generation circuit 71 (BY) generates a first voltage waveform signal having a voltage waveform that is a basis of the first drive signal COM (BY) based on the DAC value from the printer-side controller 60, and performs first current amplification. The circuit 72 (BY) generates the first drive signal COM (BY) by amplifying the current of the first voltage waveform signal. Similarly, the second waveform generation circuit 71 (CM) generates a second voltage waveform signal having a voltage waveform that is the basis of the second drive signal COM (CM) based on the DAC value from the printer-side controller 60, and The two-current amplifier circuit 72 (CM) generates the second drive signal COM (CM) by amplifying the current of the second voltage waveform signal. A first dummy load DL (BY) composed of a dummy resistor DR and a dummy capacitor DC is connected to the signal line for the first drive signal COM (BY). Further, a second dummy load DL (CM) composed of a dummy resistor DR and a dummy capacitor DC is connected to the signal line for the second drive signal COM (CM).

  The first drive signal COM (BY) is applied to each piezo element 413 belonging to the nozzle row Nk and each piezo element 413 belonging to the nozzle row Ny. The second drive signal COM (CM) is applied to each piezo element 413 belonging to the nozzle row Nc and each piezo element 413 belonging to the nozzle row Nm. The application of the first drive signal COM (BY) to each piezo element 413 belonging to the nozzle row Nk is performed by the black ink block BL (Nk) included in the head controller HC, and each piezo element belonging to the nozzle row Ny. The first drive signal COM (BY) is applied to 413 by the yellow ink block BL (Ny). Similarly, application of the second drive signal COM (CM) to each piezo element 413 belonging to the nozzle row Nc is performed by the cyan ink block BL (Nc), and the second drive signal COM (CM) is applied to each piezo element 413 belonging to the nozzle row Nm. The application of the two drive signals COM (CM) is performed by the magenta ink block BL (Nm).

  That is, for the black ink block BL (Nk), necessary ones from a plurality of waveform portions (described later) included in the first drive signal COM (BY) are selected according to the dot formation data SI, and the nozzle row Nk is selected. Apply to a plurality of piezo elements 413 to which it belongs. For the yellow ink block BL (Ny), a necessary one is selected from a plurality of waveform portions of the first drive signal COM (BY) according to the dot formation data SI, and a plurality of piezoelectric elements belonging to the nozzle row Ny are selected. Applied to the element 413. Similarly, the block BL (Nc) for cyan ink applies the necessary ones from the plurality of waveform portions included in the second drive signal COM (CM) to the plurality of piezo elements 413 belonging to the nozzle row Nc, and the magenta ink block BL (Nc). In the block BL (Nm), the necessary ones from the plurality of waveform portions included in the second drive signal COM (CM) are applied to the plurality of piezo elements 413 belonging to the nozzle row Nm. In the third embodiment, the piezo elements 413 belonging to the nozzle rows Nk and Ny (corresponding to a certain group) and the piezo elements 413 belonging to the nozzle rows Nc and Nm (corresponding to other groups) are different. Since the drive signals COM (BY) and COM (CM) are operated, the operation of the piezo element 413 can be adjusted for each group by adjusting the drive signals COM (BY) and COM (CM). For example, the same operation can be performed by adjusting the characteristic variation of the piezo element 413 for each group.

  Note that these blocks BL (Nk) to BL (Nm) are configured in the same manner as in the first embodiment, and thus detailed description thereof is omitted.

<Regarding Generated Drive Signals COM (BY), COM (CM)>
As shown in FIGS. 17A and 17B, the drive signal generation circuit 70 includes a first drive signal COM (BY) having three waveform portions SS1A to SS3A and a second drive signal COM having three waveform portions SS1B to SS3B. (CM) are simultaneously generated in the printing period T. The waveform portion SS1A is generated in the period T1, and has the first drive pulse PS21. The waveform portion SS2A is generated in the period T2, and has the second drive pulse PS22. The waveform portion SS3A is generated in the period T3 and has a third drive pulse PS23. The waveform section SS1B is generated in the period T1, and has a fourth drive pulse PS24. The waveform section SS2B is generated in the period T2, and has a fifth drive pulse PS25. The waveform section SS3B is generated in the period T3 and has a sixth drive pulse PS26.

  These drive pulses PS21 to PS26 all have the same voltage waveform. That is, this is for causing the piezo element 413 to perform the same operation. Therefore, in the third embodiment, an operation for causing the piezo element 413 to perform the N-th waveform portion on the first drive signal COM (BY) side is performed by the N-th waveform portion on the second drive signal COM (CM) side. The operation is the same as that performed by the element 413. In the third embodiment, the operation start timing by the Nth waveform section on the first drive signal COM (BY) side is the start timing of the operation by the Nth waveform section on the second drive signal COM (CM) side. The charging period of the piezo element 413 by the Nth waveform portion on the first drive signal COM (BY) side and the charging of the piezo element 413 by the Nth waveform portion on the second drive signal COM (CM) side The period is not overlapped.

  Specifically, the operation start timing by each waveform unit SS1B to SS3B on the second drive signal COM (CM) side is determined from the operation start timing by each waveform unit SS1A to SS3A on the first drive signal COM (BY) side. By making it faster, the charging periods do not overlap. That is, the charging period Ti of the piezo element 413 by the waveform section SS1B is determined to end before the charging period Tj of the piezo element 413 by the waveform section SS1A starts. The relationship between the charging period Tk by the waveform section SS2B and the charging period Tl by the waveform section SS2A and the relationship between the charging period Tm by the waveform section SS3B and the charging period Tn by the waveform section SS3A are the same.

  As a result, as shown in FIG. 17C, the maximum value of the current during charging can be suppressed and the power consumption can be suppressed as in the first embodiment described above. In this embodiment, the plurality of piezo elements 413 belonging to the two nozzle rows Nk and Ny are charged / discharged by the first drive signal COM (BY), and the two nozzle rows Nc are supplied by the second drive signal COM (CM). , Nm, the plurality of piezo elements 413 are charged and discharged. In this regard, a plurality of piezo elements 413 may be grouped for each nozzle row, and charging / discharging may be performed with four types of drive signals COM.

=== About 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, the disclosure of a control device for controlling the liquid ejection head and the disclosure of a program and code for controlling the liquid ejection device and the control device are also included. Further, this embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About drive signal>
In the first embodiment described above, the first drive signal COM_A has three waveform portions (SS11 to SS13, etc.), and the second drive signal COM_B also has three waveform portions (SS21 to SS23). However, the number of waveform portions is not limited to this number. Each drive signal COM_A and COM_B may have a plurality of waveform portions. Further, in the first embodiment, the configuration in which two types of drive signals, the first drive signal COM_A and the second drive signal COM_B, are generated simultaneously over the printing period T is exemplified. However, there are two types of drive signals COM. It is not limited. Even if there are three or more types, the same can be implemented.

<Elements that operate to eject ink>
In each of the above-described embodiments, the piezo element 413 is exemplified as an element that performs an operation for ejecting ink. A plurality of the piezoelectric elements 413 are provided corresponding to the nozzles Nz, and are divided into a plurality of groups for each nozzle row. This grouping is not limited to each nozzle row. For example, there is a head that discharges cyan ink, magenta ink, and yellow ink from one nozzle row. In such a head, the piezo elements 413 may be grouped for each type of ejected ink.

  The piezoelectric element 413 expands the pressure chamber 412 by increasing the potential and contracts the pressure chamber 412 by decreasing the potential. Regarding this piezo element, an element that contracts the pressure chamber 412 by increasing the potential and expands the pressure chamber 413 by decreasing the potential may be used. In addition, it is considered that the same effect can be obtained as long as an element that performs an operation for ejecting ink performs an operation for ejecting ink by charging and discharging.

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

1 is a diagram illustrating a configuration of a printing system. It is a block diagram explaining the structure of a computer and a printer. FIG. 2 is a diagram illustrating a configuration of a printer. It is sectional drawing of a head. It is a figure explaining the nozzle row provided in the head. It is a block diagram for demonstrating the structure of a drive signal generation circuit. It is a figure for demonstrating the structure of a head control part. It is the figure which simplified and showed the path | route for applying a drive signal to a piezoelectric element. 3 is a flowchart illustrating a printing operation of a printer. It is a figure which shows the 1st drive signal, 2nd drive signal, latch signal, 1st change signal, and 2nd change signal which are produced | generated by dot formation operation | movement. It is a figure which shows the specific content of switch operation information. FIG. 12A is a diagram illustrating the relationship between the voltage waveform and the current waveform for the waveform section SS11 and the waveform section SS21. FIG. 12B is a diagram schematically illustrating the amount of current flowing from the power supply unit in the period T1. FIG. 13A is a diagram illustrating the relationship between the voltage waveform and the current waveform for the comparative example. FIG. 13B is a diagram schematically illustrating the amount of current flowing from the power supply unit in the comparative example. It is a figure explaining the 1st drive signal and the 2nd drive signal which are generated in a 2nd embodiment. It is a figure explaining the electric current when the 1st drive signal and the 2nd drive signal are impressed to a piezo element etc. It is a figure for demonstrating the structure of 3rd Embodiment. FIG. 17A is a diagram illustrating drive signals for black ink and yellow ink. FIG. 17B is a diagram illustrating drive signals for cyan ink and magenta ink. FIG. 17C is a diagram schematically illustrating a current when the piezoelectric element is charged.

Explanation of symbols

1 printer, 20 paper transport mechanism, 21 transport motor, 22 transport roller,
30 Carriage moving mechanism, 31 Carriage motor, 32 Guide shaft,
33 timing belt, 34 drive pulley, 35 idler pulley,
40 head units, 41 heads, 411 common ink chamber,
412 pressure chamber, 413 piezo element, 414 diaphragm, 50 detector group,
51 linear encoder, 60 printer 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, 72A first current amplification circuit,
70B second drive signal generation unit, 71B second waveform generation circuit,
72B second current amplification circuit, 81A first shift register,
81B second shift register, 81C third shift register,
82A first latch circuit, 82B second latch circuit, 82C third latch circuit,
83 Control logic, 83a Shift register for switch control information,
83b pattern register, 84 decoder, 85A first switch,
85B second switch, 100 printing system, 110 computer,
111 Host side controller, 112 interface unit, 113 CPU,
114 memory, 120 display device, 130 input device, 140 recording / reproducing device,
PWS power supply, DLA first dummy load, DRA first dummy resistor,
DCA first dummy capacitor, DLB second dummy load,
DRB second dummy resistor, DCB second dummy capacitor,
Tr1 NPN type transistor, Tr2 PNP type transistor,
HC head control unit, BL block, BL (Nk) to BL (Nm) block,
CR carriage, Nz nozzle, Nk to Ny nozzle row, S paper,
CLK clock, SI dot formation data, LAT latch signal,
CH_A first change signal, CH_B second change signal,
q0 to q5 switch control information for the first switch,
q6-q11 switch control information for the second switch,
SW_A first switch operation information,
SW_B second switch operation information,
COM drive signal, COM_A first drive signal, COM (BY) first drive signal,
COM_A ′ first voltage waveform signal, COM_B second drive signal,
COM (CM) second drive signal, COM_B ′ second voltage waveform signal,
T printing period, T1 to T3 period, T11 to T13 period, T21 to T23 period,
SS11-SS13 waveform section, SS21-SS23 waveform section,
SS31-SS33 waveform section, SS41-SS43 waveform section,
SS1A to SS3A waveform section, SS1B to SS3B waveform section,
PS1 first drive pulse, PS11 first drive pulse, PS21 first drive pulse,
PS2 second drive pulse, PS12 second drive pulse, PS22 second drive pulse,
PS3 third drive pulse, PS13 third drive pulse, PS23 third drive pulse,
PS4 4th drive pulse, PS14 4th drive pulse, PS24 4th drive pulse,
PS5 5th drive pulse, PS15 5th drive pulse, PS25 5th drive pulse,
PS6 6th drive pulse, PS16 6th drive pulse, PS26 6th drive pulse

Claims (13)

(A) a liquid discharge head having a plurality of elements that operate to discharge liquid by charging and discharging;
(B) a power source used when charging the plurality of elements;
(C) a first drive signal having a plurality of waveform portions of voltage change patterns determined according to operations to be performed by the plurality of elements, and a voltage change pattern determined according to operations to be performed by the plurality of elements. Charging / discharging the plurality of elements by simultaneously generating a second drive signal having a plurality of waveform sections in a certain period and selectively applying a necessary waveform section to each of the plurality of elements A control unit,
The voltage change pattern is determined so that the charging period of the element by the Nth waveform portion on the first drive signal side and the charging period of the element by the Nth waveform portion on the second drive signal side do not overlap. A charge / discharge control unit for generating a first drive signal and the second drive signal;
A liquid ejection apparatus having (D). The liquid ejection device according to claim 1,
The charge / discharge control unit
A first capacitor charged and discharged by the first drive signal regardless of the element;
And a second capacitor that is charged and discharged by the second drive signal regardless of the element. The liquid ejection device according to claim 1 or 2, wherein
The liquid discharge head is
A pressure chamber whose volume is changed by operation of the element;
A nozzle communicated with the pressure chamber;
The element is
A liquid ejection apparatus that operates to contract the volume of the pressure chamber by charging. The liquid ejection device according to claim 3,
The element is
A liquid ejection device that is a piezo element. The liquid ejection device according to any one of claims 1 to 4,
The charge / discharge control unit
A drive signal generator for generating the first drive signal and the second drive signal;
A signal for selecting a required waveform portion from the plurality of waveform portions included in the first drive signal and the plurality of waveform portions included in the second drive signal in accordance with the discharge amount of the liquid, and applying the selected waveform portion to a certain element. A liquid ejection apparatus having an application unit. The liquid ejection device according to claim 5,
The drive signal generator is
The first drive signal in which the operation to be performed by the element by the Nth waveform portion on the first drive signal side is different from the operation to be performed by the element by the Nth waveform portion on the second drive signal side, and A liquid ejection device that generates a second drive signal. The liquid ejection device according to claim 6,
The drive signal generator is
Generating the first drive signal and the second drive signal in which the generation period of the Nth waveform portion on the first drive signal side is different from the generation period of the Nth waveform portion on the second drive signal side; Liquid ejection device. The liquid ejection device according to any one of claims 1 to 4,
The liquid discharge head is
A plurality of elements that operate to discharge liquid by charging and discharging, and have a plurality of elements divided into a plurality of groups,
The charge / discharge control unit
A drive signal generator for generating the first drive signal and the second drive signal;
Necessary ones from a plurality of waveform parts of the first drive signal are selected according to the discharge amount of the liquid and applied to the elements belonging to a certain group, and necessary from the plurality of waveform parts of the second drive signal. A liquid ejecting apparatus comprising: a signal applying unit configured to select a device according to a liquid ejection amount and apply the selected device to the element belonging to another group. The liquid ejection device according to claim 8, wherein
The drive signal generator is
The operation to be performed on the element by the Nth waveform portion on the first drive signal side is the same as the operation to be performed on the element by the Nth waveform portion on the second drive signal side. The operation start timing by the Nth waveform portion is different from the operation start timing by the Nth waveform portion on the second drive signal side, whereby the Nth waveform portion on the first drive signal side A liquid ejecting apparatus that generates the first drive signal and the second drive signal so that a charge period of the element does not overlap with a charge period of the element by the Nth waveform portion on the second drive signal side. A liquid ejection apparatus according to any one of claims 5 to 9,
The drive signal generator is
A first voltage waveform generator that generates a first voltage waveform signal that is a basis of the first drive signal;
A first current amplifier connected to the power source and amplifying the current of the first voltage waveform signal;
A second voltage waveform generator that generates a second voltage waveform signal that is a basis of the second drive signal;
A liquid ejection apparatus, comprising: a second current amplification unit that is connected to the power source and amplifies the current of the second voltage waveform signal. (A) A plurality of elements that perform an operation for discharging liquid by charging and discharging, a plurality of elements divided into a plurality of groups, a pressure chamber whose volume is changed by the operation of the elements, and a pressure chamber A liquid discharge head having a communicating nozzle,
As the element, a liquid discharge head having a piezoelectric element that operates to contract the volume of the pressure chamber by charging;
(B) a power source used when charging the plurality of elements;
(C) a first drive signal having a plurality of waveform portions of voltage change patterns determined according to operations to be performed by the plurality of elements, and a voltage change pattern determined according to operations to be performed by the plurality of elements. Charge / discharge that simultaneously generates a second drive signal having a plurality of waveform portions in a certain period and selectively applies the necessary waveform portion to each of the plurality of devices to charge / discharge the plurality of devices. A control unit,
The operation to be performed by the element by the Nth waveform portion on the first drive signal side is different from the operation to be performed by the element by the Nth waveform portion on the second drive signal side, and the first drive signal The first drive signal and the second drive signal, wherein the generation period of the N-th waveform portion on the side differs from the generation period of the N-th waveform portion on the second drive signal side,
Or
The operation to be performed on the element by the Nth waveform portion on the first drive signal side is the same as the operation to be performed on the element by the Nth waveform portion on the second drive signal side. The start timing of the operation by the Nth waveform portion is different from the start timing of the operation by the Nth waveform portion on the second drive signal side, whereby the Nth waveform portion on the first drive signal side A drive signal generation unit configured to generate the first drive signal and the second drive signal so that a charge period of the element does not overlap with a charge period of the element by the Nth waveform portion on the second drive signal side;
A necessary one is selected from a plurality of waveform portions included in the first drive signal and a plurality of waveform portions included in the second drive signal in accordance with a discharge amount of the liquid, and the selected waveform portion is applied to a certain element. Alternatively, a plurality of waveform portions included in the second drive signal may be selected from a plurality of waveform portions included in the first drive signal according to the liquid discharge amount and applied to the elements belonging to a certain group. A signal applying unit that selects a necessary one according to the discharge amount of the liquid and applies it to the element belonging to another group;
A first capacitor charged and discharged by the first drive signal regardless of the element;
A second capacitor charged and discharged by the second drive signal regardless of the element,
The voltage change pattern is determined such that the charging period of the element by the Nth waveform portion on the first drive signal side and the charging period of the element by the Nth waveform portion on the second drive signal side do not overlap. A charge / discharge control unit for generating the first drive signal and the second drive signal;
Have
(D) The drive signal generation unit includes:
A first voltage waveform generation unit that generates a first voltage waveform signal that is a basis of the first drive signal;
A first current amplifier connected to the power source and amplifying the current of the first voltage waveform signal;
A second voltage waveform generation unit that generates a second voltage waveform signal that is a basis of the second drive signal;
A second current amplifier connected to the power source and amplifying the current of the second voltage waveform signal;
A liquid ejection apparatus having (E). (A) A liquid discharge method using a plurality of elements that operate to discharge liquid by charge and discharge,
(B) a first drive signal having a plurality of waveform portions of voltage change patterns determined according to operations to be performed by the plurality of elements, and a voltage change pattern determined according to operations to be performed by the plurality of elements. A second drive signal having a plurality of waveform portions, the charge period of the element by the Nth waveform portion on the first drive signal side, and the charge period of the device by the Nth waveform portion on the second drive signal side, Simultaneously generating a first drive signal and a second drive signal in which the voltage change pattern is determined so as not to overlap each other in a certain period;
(C) charging and discharging the plurality of elements by selectively applying a necessary waveform portion to each of the plurality of elements;
A liquid discharge method for performing (D). (A) A program for controlling a liquid ejection apparatus having a plurality of elements that perform an operation for ejecting liquid by charging and discharging,
(B) a first drive signal having a plurality of waveform portions of voltage change patterns determined according to operations to be performed by the plurality of elements, and a voltage change pattern determined according to operations to be performed by the plurality of elements. A second drive signal having a plurality of waveform portions, the charge period of the element by the Nth waveform portion on the first drive signal side, and the charge period of the device by the Nth waveform portion on the second drive signal side, Generating simultaneously the first drive signal and the second drive signal in which the voltage change pattern is determined so as not to overlap each other in a certain period;
(C) selectively applying a necessary waveform portion to each of the plurality of elements to charge / discharge the plurality of elements;
A program for causing the liquid ejection apparatus to perform (D).

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