JP2016005560A - Control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid injection device capable of reducing a power loss due to a damping resistor, and further to provide a liquid injection type printer.SOLUTION: When a signal from a drive waveform signal generation circuit 25 is subjected to pulse modulation in a modulation circuit 26, a pulse-modulated signal PWM is subjected to power amplification in a digital power amplification circuit 28 and a power-amplified and pulse-modulated signal APWM is smoothed by a smoothing filter 29 so as to obtain a drive signal COM, resonance characteristics can be compensated at the time of non-use of the a damping resistor for the smooth filter 29 by setting transfer characteristics β of a compensator 32 such that frequency characteristics of: electrostatic capacitance of the modulation circuit 26, the digital power amplifier circuit 28, the smooth filter 29 and an actuator 22 driven; and a drive signal feedback closed loop constituted of the compensator 32 are constant up to a predetermined attenuation starting frequency. Consequently, the damping resistor is unnecessary, and a power loss can be reduced.

Description

  The present invention relates to a liquid ejecting apparatus that amplifies power of a drive signal to an actuator that ejects liquid, and ejects a minute liquid from a nozzle of a liquid ejecting head to form fine particles (dots) on a print medium. This is suitable for a liquid jet printing apparatus that prints characters, images, and the like.

  In a liquid ejection type printing apparatus, an actuator such as a piezoelectric element is provided in order to eject liquid from a nozzle of a liquid ejection head, and a predetermined drive signal must be applied to the actuator. Since this drive signal has a relatively high voltage, the drive waveform signal that becomes the reference of the drive signal must be power amplified by the power amplification circuit. Therefore, in Patent Document 1 below, a digital power amplifier circuit that is extremely small in power loss and can be downsized as compared with an analog power amplifier circuit is used, and a drive waveform signal is pulse-modulated by a modulation circuit to obtain a modulation signal. The modulated signal is power amplified by a digital power amplifier circuit to obtain a power amplified modulated signal, and the power amplified modulated signal is smoothed by a smoothing filter to obtain a drive signal.

JP-A-11-204850

However, when the actuator is a capacitive load such as a piezoelectric element, since there is no resistance component, a damping resistor is required for the smoothing filter, and there is a problem that power loss due to this damping resistor is large. That is, as is well known, when a smoothing filter is constituted by a coil and a capacitor, there is a resonance frequency represented by the inductance L of the coil and the capacitance C of the capacitor. In this case, resonance may occur due to the resonance frequency. When there is a resistance component in the circuit, resonance is suppressed (attenuated) by the resistance component. However, in the case of a capacitive load such as a piezoelectric element, resonance is suppressed because there is no resistance component or it is very small ( Remains without being attenuated). In order to suppress (attenuate) this remaining resonance, it is necessary to insert a resistor called a damping resistor for the purpose of suppressing (attenuating) the resonance in the circuit, and the resonance is consumed (attenuated) by this damping resistor. Sometimes power is consumed.
SUMMARY An advantage of some aspects of the invention is that it provides a liquid ejecting apparatus and a liquid ejecting printing apparatus capable of reducing power loss due to a damping resistance. .

  In order to solve the above problems, a liquid ejecting apparatus according to the present invention includes a drive waveform signal generation circuit that generates a drive waveform signal, a modulation circuit that modulates a signal from the drive waveform signal generation circuit into a modulation signal, and A digital power amplification circuit that amplifies the modulation signal to obtain a power amplification modulation signal, a smoothing filter that smoothes the power amplification modulation signal to obtain an actuator drive signal, and negative feedback by advancing the phase of the drive signal And a subtractor using a difference signal between the drive waveform signal and the negative feedback signal as an input signal to the modulation circuit.

  According to this liquid ejecting apparatus, since the resonance characteristic when the damping resistor is not used in the smoothing filter can be compensated by the negative feedback signal, the damping resistor becomes unnecessary and the power loss can be reduced. That is, since the difference signal between the drive waveform signal and the negative feedback signal is subjected to pulse modulation by the modulation circuit, for example, when resonance occurs in the drive signal, the difference signal is only the inverted signal corresponding to the resonance of the drive signal. Thus, if this is pulse-modulated to amplify the power and added to the drive signal, the original drive signal can be obtained.

A closed loop provided between the drive waveform signal generation circuit and the subtracter and configured by the modulation circuit, the digital power amplification circuit, the smoothing filter, the capacitance of the actuator, and the compensator; An inverse filter for correcting the frequency characteristics so as to be constant in a predetermined frequency region is provided.
According to this liquid ejecting apparatus, for example, a closed-loop frequency characteristic composed of a modulation circuit, a digital power amplification circuit, a smoothing filter, an actuator capacitance, and a compensator, which changes according to the number of actuators to be driven, is obtained. The accuracy of the drive signal can be ensured by correcting it so as to be constant in a predetermined frequency region by the inverse filter.
Further, the liquid jet printing apparatus of the present invention is characterized by using the liquid jet apparatus.

1 is a schematic front view showing a first embodiment of a liquid jet printing apparatus using a body jet device of the present invention. FIG. 2 is a plan view of the vicinity of a liquid jet head used in the liquid jet printing apparatus of FIG. 1. FIG. 2 is a block diagram of a control device of the liquid jet printing apparatus of FIG. 1. 6 is an explanatory diagram of a drive signal for driving an actuator in each liquid ejecting head. FIG. It is a block diagram of a switching controller. It is a block diagram which shows an example of the drive circuit of an actuator. It is a block diagram of the modulation circuit of FIG. FIG. 7 is a block diagram of the digital power amplifier circuit of FIG. 6. It is a block diagram of the smoothing filter of FIG. It is a block diagram of the compensator of FIG. It is explanatory drawing of the frequency characteristic of the smoothing filter of FIG. It is explanatory drawing of the closed loop by a modulation circuit, a digital power amplifier circuit, a smoothing filter, an actuator, and a compensator. It is explanatory drawing of frequency characteristic correction | amendment of the closed loop by a compensator. It is a block diagram of an actuator drive circuit showing a second embodiment of a liquid jet printing apparatus using the body jet device of the present invention. It is explanatory drawing of the closed loop in the actuator drive circuit of FIG. It is explanatory drawing of the frequency characteristic correction | amendment of the closed loop by an inverse filter.

Next, as a first embodiment of the liquid ejecting apparatus of the present invention, a liquid ejecting type printing apparatus used will be described.
FIG. 1 is a schematic configuration diagram of the liquid jet printing apparatus according to the first embodiment. In FIG. 1, a print medium 1 is transported in the direction of an arrow from the left to the right in the figure, and a printing area in the middle of the transport It is a line head type printing apparatus printed by

  Reference numeral 2 in FIG. 1 denotes a plurality of liquid ejecting heads provided above the conveyance line of the print medium 1, arranged in two rows in the print medium conveyance direction and in a direction intersecting the print medium conveyance direction. And fixed to the head fixing plate 11, respectively. A large number of nozzles are formed on the lowermost surface of each liquid jet head 2, and this surface is called a nozzle surface. As shown in FIG. 2, the nozzles are arranged in rows in the direction intersecting the print medium conveyance direction for each color of the liquid to be ejected. The rows are called nozzle rows, or the row directions are nozzles. Sometimes called the row direction. A line head that extends over the entire length in the direction intersecting the transport direction of the print medium 1 is formed by the nozzle rows of all the liquid jet heads 2 arranged in the direction intersecting the print medium transport direction. When the print medium 1 passes below the nozzle surfaces of these liquid ejecting heads 2, printing is performed by ejecting liquid from a large number of nozzles formed on the nozzle surfaces.

  For example, liquid such as yellow (Y), magenta (M), cyan (C), and black (K) ink is supplied to the liquid ejecting head 2 from a liquid tank (not shown) via a liquid supply tube. The Then, by ejecting a necessary amount of liquid from a nozzle formed in the liquid ejecting head 2 to a necessary portion at the same time, minute dots are formed on the print medium 1. By performing this for each color, printing by one pass can be performed only by passing the print medium 1 conveyed by the conveyance unit 4 once.

  As a method for ejecting the liquid from the nozzle of the liquid ejecting head 2, there are an electrostatic method, a piezo method, a film boiling liquid ejecting method, and the like. In this embodiment, the piezo method is used. In the piezo method, when a drive signal is given to a piezoelectric element that is an actuator, the diaphragm in the cavity is displaced to cause a pressure change in the cavity, and the liquid is ejected from the nozzle by the pressure change. The liquid ejection amount can be adjusted by adjusting the peak value of the drive signal and the voltage increase / decrease slope. Note that the present invention can be similarly applied to liquid ejection methods other than the piezo method.

  Below the liquid jet head 2, a transport unit 4 for transporting the print medium 1 in the transport direction is provided. The conveying unit 4 is configured by winding a conveying belt 6 around a driving roller 8 and a driven roller 9, and an electric motor (not shown) is connected to the driving roller 8. An adsorption device (not shown) for adsorbing the print medium 1 to the surface of the conveyance belt 6 is provided inside the conveyance belt 6. As this adsorption device, for example, an air suction device that adsorbs the print medium 1 to the conveyance belt 6 by negative pressure, an electrostatic adsorption device that adsorbs the print medium 1 to the conveyance belt 6 by electrostatic force, or the like is used. Accordingly, when only one sheet of the printing medium 1 is fed from the sheet feeding unit 3 to the conveying belt 6 by the sheet feeding roller 5 and the driving roller 8 is rotationally driven by the electric motor, the conveying belt 6 is rotated in the printing medium conveying direction. The print medium 1 is adsorbed to the conveyance belt 6 by the adsorption device and conveyed. While the printing medium 1 is being conveyed, printing is performed by ejecting liquid from the liquid ejecting head 2. The print medium 1 that has finished printing is discharged to the paper discharge unit 10 on the downstream side in the transport direction. The transport belt 6 is attached with a printing reference signal output device composed of, for example, a linear encoder. This printing reference signal output device pays attention to the fact that the transport belt 6 and the print medium 1 that is attracted and transported by the transport belt 6 are moved synchronously, and after the print medium 1 passes through a predetermined position in the transport path. A pulse signal corresponding to the printing resolution required in accordance with the movement of the conveying belt 6 is output, and a drive signal is output from the drive circuit described later to the actuator 22 in accordance with the pulse signal, whereby a predetermined signal on the print medium 1 is output. A liquid of a predetermined color is ejected to the position, and a predetermined image is drawn on the print medium 1 by the dots.

  A control device for controlling the liquid jet printing apparatus is provided in the liquid jet printing apparatus using the liquid jet apparatus according to the present embodiment. As shown in FIG. 3, the control device executes an input interface 61 for reading print data input from the host computer 60, and arithmetic processing such as print processing based on the print data input from the input interface 61. A control unit 62 constituted by a microcomputer, a paper feed roller motor driver 63 for driving and controlling the paper feed roller motor 17 connected to the paper feed roller 5, and a head driver 65 for driving and controlling the liquid ejecting head 2 An electric motor driver 66 for driving and controlling the electric motor 7 connected to the drive roller 8, a paper feed roller motor driver 63, a head driver 65, an electric motor driver 66 and a paper feed roller motor 17, the liquid ejecting head 2, An interface 67 for connecting the electric motor 7 is provided.

  The control unit 62 temporarily stores a CPU (Central Processing Unit) 62a that executes various processes such as a print process, and print data input through the input interface 61 or various data when the print data print process is executed. A random access memory (RAM) 62c that temporarily stores a program such as a print process or a nonvolatile semiconductor memory that stores a control program executed by the CPU 62a. ) 62d. When the control unit 62 obtains print data (image data) from the host computer 60 via the input interface 61, the CPU 62a executes a predetermined process on the print data, and from which nozzle the liquid is ejected. Alternatively, nozzle selection data (drive pulse selection data) indicating how much liquid is to be ejected is calculated, and based on the print data, drive pulse selection data, and input data from various sensors, the paper feed roller motor driver 63, the head A drive signal and a control signal are output to the driver 65 and the electric motor driver 66. By these drive signals and control signals, the paper feed roller motor 17, the electric motor 7, the actuator 22 in the liquid ejecting head 2, etc. are actuated to feed, convey and discharge the print medium 1, and the print medium 1. The printing process is executed. Each component in the control unit 62 is electrically connected through a bus (not shown).

  FIG. 4 shows an example of a drive signal COM that is supplied to the liquid ejecting head 2 from the control device of the liquid ejecting type printing apparatus using the liquid ejecting apparatus according to the present embodiment and drives the actuator 22 made of a piezoelectric element. . In the present embodiment, a signal whose voltage changes centering on the intermediate voltage is used. This drive signal COM is a time series connection of drive pulses PCOM as unit drive signals for driving the actuator 22 to eject liquid, and a cavity (pressure chamber) in which the rising portion of the drive pulse PCOM communicates with the nozzle. ) Is expanded and the liquid is drawn in (it can be said that the meniscus is drawn in considering the liquid ejection surface), and the falling portion of the drive pulse PCOM reduces the volume of the cavity to push out the liquid (the liquid Considering the ejection surface, it can be said that the meniscus is extruded). As a result of the liquid being extruded, the liquid is ejected from the nozzle.

  By variously changing the voltage increase / decrease slope and peak value of the drive pulse PCOM consisting of this voltage trapezoidal wave, it is possible to change the amount of liquid drawn in, the speed of drawing in, the amount of liquid pushed out, and the speed of extrusion. Different sizes of dots can be obtained by changing the ejection amount. Therefore, even when a plurality of drive pulses PCOM are connected in time series, a single drive pulse PCOM is selected and supplied to the actuator 22 to eject liquid or select a plurality of drive pulses PCOM to select the actuator. It is possible to obtain dots of various sizes by supplying the liquid 22 and ejecting the liquid a plurality of times. That is, if a plurality of liquids are landed at the same position before the liquid is dried, it is substantially the same as ejecting a large liquid, and the size of the dots can be increased. By combining such techniques, it is possible to increase the number of gradations. Note that the driving pulse PCOM1 at the left end in FIG. This is called microvibration and is used to suppress or prevent the increase in the viscosity of the nozzle without ejecting liquid.

  In addition to the drive signal COM, the liquid ejection head 2 selects a nozzle to be ejected based on print data as a control signal from the control device of FIG. 3 and connects to the drive signal COM of an actuator 22 such as a piezoelectric element. Drive pulse selection data SI & SP for determining timing, latch signal LAT and channel for connecting the drive signal COM and the actuator 22 of the liquid ejecting head 2 based on the drive pulse selection data SI & SP after nozzle selection data is input to all nozzles A clock signal SCK for transmitting the signal CH and the drive pulse selection data SI & SP to the liquid jet head 2 as a serial signal is input. Hereinafter, the minimum unit of the drive signal for driving the actuator 22 is referred to as a drive pulse PCOM, and the entire signal in which the drive pulses PCOM are connected in time series is referred to as a drive signal COM. That is, a series of drive signals COM starts to be output in response to the latch signal LAT, and a drive pulse PCOM is output for each channel signal CH. Of the drive pulse selection data SI & SP, the drive pulse selection specific data SI is 2-bit data indicating which drive pulse PCOM is selected from the drive pulses PCOM described above, and SP is the selected drive pulse. This is 16-bit selection switch control data for on / off control of a selection switch described later in accordance with the timing of PCOM.

  FIG. 5 shows a specific configuration of a switching controller built in the liquid ejecting head 2 in order to supply the drive signal COM (drive pulse PCOM) to the actuator 22. This switching controller includes a register 211 that stores drive pulse selection data SI & SP for designating an actuator 22 such as a piezoelectric element corresponding to a nozzle that ejects liquid, and a latch circuit 212 that temporarily stores data in the register 211. The level shifter 213 connects the drive signal COM (drive pulse PCOM) to the actuator 22 such as a piezo element by converting the level of the output of the latch circuit 212 and supplying the output to the selection switch 201.

  The register 211 receives the drive pulse selection data signal SI & SP in accordance with the input pulse of the clock signal SCK, and the selection switch control data SP among them is stored at a predetermined address. The latch circuit 212 latches each output signal of the register 211 by the input latch signal LAT after the selection switch control data SP for the total number of actuators is stored in the register 211. The signal stored in the latch circuit 212 is converted by the level shifter 213 to a voltage level at which the selection switch 201 at the next stage can be turned on / off. This is because the drive signal COM (drive pulse PCOM) is higher than the output voltage of the latch circuit 212, and the operating voltage range of the selection switch 201 is set higher accordingly. Therefore, the actuator 22 such as a piezoelectric element whose selection switch 201 is closed by the level shifter 213 is connected to the drive signal COM (drive pulse PCOM) at the connection timing of the drive pulse selection data SI & SP (selection switch control data SP). Further, after the drive pulse selection data SI & SP (selection switch control data SP) of the register 211 is stored in the latch circuit 212, the next print information is input to the register 211, and stored in the latch circuit 212 in accordance with the liquid ejection timing. Update data sequentially. In addition, the code | symbol HGND in a figure is a ground end of actuators 22, such as a piezoelectric element. Further, even after the actuator 22 such as a piezoelectric element is disconnected from the drive signal COM (drive pulse PCOM) by the selection switch 201, the input voltage of the actuator 22 is maintained at the voltage just before the disconnection.

  FIG. 6 shows a schematic configuration of the drive circuit of the actuator 22. This actuator drive circuit is constructed in the control unit 62 and the head driver 65 in the control circuit. The drive circuit according to the present embodiment generates a drive waveform signal WCOM serving as a reference of a signal for controlling the drive of the actuator 22 based on the drive waveform data DWCOM stored in advance, that is, based on the drive signal COM (drive pulse PCOM). Drive waveform signal generation circuit 25 to be generated, a difference between the drive waveform signal WCOM generated by the drive waveform signal generation circuit 25 and a negative feedback signal from a compensator described later, specifically, a negative feedback signal from the drive waveform signal WCOM An adder / subtractor 31 as a subtractor that outputs a difference signal WCOMdef obtained by subtracting the signal, a modulation circuit 26 that outputs a modulation signal PWM by pulse-modulating the difference signal WCOMdef from the adder / subtractor 31, and a modulation signal PWM from the modulation circuit 26 A digital power amplification circuit 28 that amplifies the power of the signal and outputs a power amplification modulation signal APWM, and a digital power amplification A smoothing filter 29 that smoothes the power amplification modulation signal APWM from the path 28 and outputs it as the drive signal COM, and a compensator 32 that advances the phase of the drive signal COM and outputs the negative feedback signal CPST. .

The drive waveform signal generation circuit 25 holds and outputs the drive waveform data DWCOM read from the waveform memory for a predetermined sampling period.
As the modulation circuit 26 that performs pulse modulation of the drive waveform signal WCOM, as shown in FIG. 7, a known pulse width modulation (PWM) circuit is used. In the pulse width modulation, the triangular wave oscillator 34 that outputs a triangular wave signal having a predetermined frequency is compared with the triangular wave signal and the drive waveform signal WCOM. And a comparator 35 that outputs PWM.
The drive waveform signal generation circuit 25, the adder / subtractor 31 as a subtractor, and the modulation circuit 26 can be configured by arithmetic processing by a program. The modulation circuit 26 may be a known pulse modulation circuit such as a pulse density modulation (PDM) circuit.

  As shown in FIG. 8, the digital power amplifier circuit 28 includes a half-bridge output stage 21 composed of a high-side switching element Q1 and a low-side switching element Q2 for substantially amplifying power, and a modulation from the modulation circuit 26. A gate drive circuit 30 is provided for adjusting the gate-source signals GH and GL of the high-side switching element Q1 and the low-side switching element Q2 based on the signal PWM. In the digital power amplifier circuit 28, when the modulation signal is at a high level, the gate-source signal GH of the high-side switching element Q1 is at a high level, and the gate-source signal GL of the low-side switching element Q2 is at a low level. Therefore, the high-side switching element Q1 is turned on and the low-side switching element Q2 is turned off. As a result, the output voltage Va of the half bridge output stage 21 becomes the supply voltage VDD. On the other hand, when the modulation signal is at a low level, the gate-source signal GH of the high-side switching element Q1 is at a low level, and the gate-source signal GL of the low-side switching element Q2 is at a high level. The side switching element Q1 is turned off and the low side switching element Q2 is turned on. As a result, the output voltage Va of the half-bridge output stage 21 becomes zero.

  When the high-side switching element Q1 and the low-side switching element Q2 are digitally driven in this way, a current flows through the on-state switching element, but the resistance value between the drain and source is very small, and almost no loss occurs. do not do. Further, since no current flows through the switching element in the off state, no loss occurs. Accordingly, the loss itself of the digital power amplifier circuit 28 is extremely small, and a switching element such as a small MOSFET can be used.

As the smoothing filter 29, a secondary low-pass filter including one capacitor C and one coil L was used as shown in FIG. The smoothing filter 29 attenuates and removes the modulation frequency generated by the modulation circuit 26, that is, the frequency component of pulse modulation, and outputs a drive signal COM to the actuator 22 via the selection switch 201.
As shown in FIG. 10, the compensator 32 includes a single capacitor C1 and a single resistor R, and includes a high-pass filter that advances the phase of the drive signal COM and outputs a negative feedback signal CPST. Note that by making the resistor R of the compensator 32 have a large resistance value, the value of the current flowing through the resistor R can be reduced, and the power loss can be reduced.

  In the frequency characteristic of the smoothing filter 29 of the first embodiment having no damping resistance, resonance occurs in the vicinity of the attenuation start frequency of the low-pass filter, as shown by a solid line in FIG. Of course, such a fluctuation in gain is not desirable, and a frequency characteristic as indicated by a two-dot chain line in FIG. 11 where the gain is constant up to the attenuation start frequency is ideal. In the audio field and the like, an ideal frequency characteristic may be obtained without adding a damping resistor due to the influence of floating resistance, but the actuator 22 according to the first embodiment including a capacitive load such as a piezoelectric element may be used. Since there is no resistance component, a damping resistance is indispensable in order to achieve the frequency characteristics as shown by the two-dot chain line by the smoothing filter 29 itself, and the power loss increases due to this damping resistance.

  Of the actuator drive circuit of the first embodiment, the adder / subtractor 31, the modulation circuit 26, the digital power amplifier circuit 28, the smoothing filter 29 (substantially, a capacitive load such as a piezoelectric element is added to the capacitor C in the smoothing filter 29). 12) and the closed loop by the compensator 32 appear as shown in FIG. A frequency having the above-described resonance, where A is a gain of a drive signal output system including a modulation circuit 26, a digital power amplifier circuit 28, and a smoothing filter 29 (including the capacitance of the driven actuator 22) and H is a transfer characteristic. The characteristic appears as AH as shown in FIG. On the other hand, when the transfer characteristic of the compensator 32 is β, the closed loop transfer characteristic G shown in FIG.

  Accordingly, the transfer characteristic β of the compensator 32 may be set so that the closed-loop transfer characteristic G is constant up to a predetermined attenuation start frequency, as indicated by a two-dot chain line in FIG. Specifically, for example, 1 / (A · H) of the equation 1 appears as a broken line in the figure. Therefore, the transfer characteristic β of the compensator 32 is set as a solid line, and β + 1 / (A · H) is If it becomes like a one-dot chain line, the closed loop transfer function G can be set like a two-dot chain line. As described above, a power loss occurs due to the current flowing through the resistor R of the compensator 32. By increasing the resistance value of the resistor R, the current value can be reduced, thereby suppressing the power loss. be able to.

  As described above, in the liquid ejecting apparatus according to the first embodiment, the drive waveform signal generation circuit 25 generates the drive waveform signal WCOM, the signal from the drive waveform signal generation circuit 25 is pulse-modulated by the modulation circuit 26, and the modulation signal PWM is generated. Is amplified by the digital power amplification circuit 28, and the power amplification modulation signal APWM is smoothed by the smoothing filter 29 to be used as the drive signal COM (drive pulse PCOM) of the actuator 22. The compensator 32 drives the drive signal COM (drive pulse). PCOM) is advanced to a negative feedback signal CPST, and the adder / subtractor 31 as a subtractor uses the difference signal WCOMdef between the drive waveform signal WCOM and the negative feedback signal CPST as an input signal to the modulation circuit 26. Resonance characteristics when no damping resistor is used for the filter 29 are compensated by the negative feedback signal CPST. It is possible, damping resistor is not required, it is possible to reduce the power loss.

Next, a second embodiment of the liquid ejecting apparatus of the invention will be described. The liquid ejecting apparatus of the present embodiment is applied to the liquid ejecting printing apparatus as in the first embodiment. The schematic configuration, the vicinity of the liquid ejecting head, the control device, the drive signal, and the switching controller are as follows. The same as in the first embodiment. Therefore, in the following description, the same code | symbol is attached | subjected about the structure same as 1st Embodiment, and the description is abbreviate | omitted. In the second embodiment, an inverse filter 23 is interposed between the drive waveform signal generation circuit 25 and the adder / subtractor 31. The inverse filter 23 includes a control unit inside, and can control its own frequency characteristics according to the number of actuators 22 to be driven. The inverse filter 23 can be constructed by a calculation process by a program. Therefore, the inverse filter 23 including the control unit can be constructed in the control unit 62 in the control circuit. That is, the drive waveform signal generation circuit 25 to the modulation circuit 26 can all be digitized.
FIG. 15 shows a closed loop of the adder / subtractor 31, the modulation circuit 26, the digital power amplifier circuit 28, the smoothing filter 29, the capacitance of the actuator 22, and the compensator 32 in the actuator drive circuit according to the second embodiment. Let c be the transfer characteristic of the inverse filter 23. The transfer characteristic G0 of the entire system including the inverse filter 23 is expressed by the following two expressions.

  For example, as described in International Publication No. WO2007 / 083669, when the number of actuators 22 to be driven changes, the frequency characteristics of the closed loop change. FIG. 16 shows the features. In this case, as described above, the closed-loop resonance is suppressed by the negative feedback signal CPST from the compensator 32. Therefore, the frequency characteristics change so that the attenuation start frequency changes, and the number of actuators 22 to be driven is large. As the load increases, the attenuation start frequency decreases.

  Therefore, as a characteristic of the inverse filter 23, as shown by a broken line in FIG. 16, a so-called high-pass filter in which a high frequency band is emphasized is used, and an attenuation start frequency when the number of actuators 22 is large (when the load is large) is used. You can make it higher. Since the number of actuators 22 to be driven can be obtained from the drive pulse selection data SI & SP, for example, when the inverse filter 23 is a high-pass filter, if the gain of the high-pass filter is controlled according to the number of actuators 22 to be driven. The gain of the closed loop can be made constant in a predetermined frequency region, and thereby the attenuation start frequency necessary for the smoothing filter 29 can be kept constant.

As described above, in the liquid ejecting apparatus according to the second embodiment, the modulation circuit 26, the digital power amplification circuit 28, the smoothing filter 29, the capacitance of the actuator 22, and the compensator, which change according to the number of actuators 22 to be driven. The accuracy of the drive signal can be ensured by correcting the frequency characteristic of the closed loop composed of 32 so as to be constant in a predetermined frequency region by the inverse filter 23.
In the above embodiment, only the case where the liquid ejecting apparatus of the present invention is used in a line head type liquid ejecting printing apparatus has been described in detail. However, the liquid ejecting apparatus of the present invention is a multi-pass liquid ejecting type printing apparatus. The same applies to the apparatus.

  In addition, the liquid ejecting apparatus of the present invention may be a liquid other than ink (including a liquid material in which particles of functional material are dispersed and a fluid such as a gel) and a fluid other than a liquid (fluid) It is also possible to embody a liquid ejecting apparatus that ejects a solid that can be ejected as For example, a liquid material ejecting apparatus that ejects a liquid material that contains materials such as electrode materials and color materials used in the manufacture of liquid crystal displays, EL (electroluminescence) displays, surface-emitting displays, color filters, and the like in a dispersed or dissolved form. Further, it may be a liquid ejecting apparatus that ejects a bio-organic matter used for biochip manufacturing, or a liquid ejecting apparatus that ejects a liquid that is used as a precision pipette and serves as a sample. In addition, transparent resin liquids such as UV curable resins for forming liquid injection devices that inject lubricating oil onto precision machines such as watches and cameras, micro hemispherical lenses (optical lenses) used in optical communication elements, etc. Examples include a liquid ejecting apparatus that ejects a liquid onto a substrate, a liquid ejecting apparatus that ejects an etching solution such as acid or alkali to etch the substrate, a fluid ejecting apparatus that ejects a gel, and a powder such as toner. It may be a fluid ejection recording apparatus that ejects a solid. Furthermore, it may be a liquid ejecting apparatus as a surgical tool for incising or excising a living tissue by ejecting a liquid such as water or saline in pulses. The present invention can be applied to any one of these injection devices.

  1 is a print medium, 2 is a liquid ejecting head, 3 is a paper feed unit, 4 is a transport unit, 5 is a paper feed roller, 6 is a transport belt, 7 is an electric motor, 8 is a drive roller, 9 is a driven roller, 10 is A paper discharge unit, 11 is a head fixing plate, 21 is a half-bridge output stage, 22 is an actuator, 23 is an inverse filter, 25 is a drive waveform signal generation circuit, 26 is a modulation circuit, 28 is a digital power amplification circuit, and 29 is a smoothing filter , 30 is a gate drive circuit, 31 is an adder / subtractor, 32 is a compensator, 34 is a triangular wave oscillator, 35 is a comparison unit, 62 is a control unit, and 65 is a head driver.

Claims (7)

A cavity communicating with a nozzle for injecting liquid;
An actuator that changes the pressure in the cavity based on a drive signal and ejects liquid from the nozzle in a pulsed manner;
A storage unit storing drive waveform data; and
A drive waveform signal generating circuit for generating a drive waveform signal based on the drive waveform data;
A modulation circuit for pulse-modulating the drive waveform signal and outputting a modulation signal;
A digital power amplifier circuit that amplifies the modulated signal to output a power amplified modulated signal;
A smoothing filter for smoothing the power amplification modulation signal and outputting the drive signal;
A compensator that advances the phase of the drive signal and outputs a negative feedback signal;
A subtractor that inputs a difference signal obtained by subtracting the negative feedback signal from the drive waveform signal to the modulation circuit;
A surgical instrument in which the modulation circuit, the digital power amplification circuit, the smoothing filter, the compensator, and the subtractor are configured in a closed loop. The surgical instrument according to claim 1,
The closed loop has a transfer characteristic in which a gain is constant from a predetermined frequency of the drive signal to an attenuation start frequency. The surgical instrument according to claim 1 or 2, wherein
The surgical instrument, wherein the compensator is set to increase a gain at a predetermined frequency of the drive signal. The surgical instrument according to claim 1, wherein
A plurality of the actuators;
The smoothing filter includes a capacitor,
A surgical instrument, wherein the actuator is connected in parallel to the capacitor. The surgical instrument according to any one of claims 1 to 4,
The compensator includes a capacitor and a resistor. The surgical instrument according to any one of claims 1 to 5,
The surgical tool, wherein the smoothing filter does not include a damping resistor. The surgical instrument according to any one of claims 1 to 6,
The digital power amplifier includes a high-side switching element, a low-side switching, and a gate drive circuit.

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