JP2011088294A - Power amplifying circuit, liquid jet apparatus, and liquid jet type printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power amplifying circuit which can reduce a circuit scale and costs by reducing the number of signal lines and of A/D converters, and to provide a liquid jet apparatus and a liquid jet type printer. <P>SOLUTION: A signal from a drive waveform signal generating circuit 25 is passed through pulse modulation by a modulating circuit 26, and the modulation signal PWM is subjected to power amplification by a digital power amplifying circuit 28. When the power-amplified modulation signal APWM is smoothed by a smoothing filter 29 to be a driving signal COM, the phase of the driving signal COM is advanced and also a power supply voltage VDD of the digital power amplifying circuit 28 is divided by a compensator 32, whereby a superposed signal SPPS is output. The superposed signal SPPS is separated by a separator 33 into a power supply voltage signal VDDS and a negative feedback signal CPSTS. A differential signal WCOMdef between a drive waveform signal WCOM and the negative feedback signal CPSTS is made an input signal to the modulating circuit 26 by an adder-subtracter 31. The modulating circuit 26 corrects the modulation signal PWM according to the power supply voltage signal VDDS. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power amplifying circuit that amplifies an input signal, for example, a liquid ejecting device that amplifies a drive signal to an actuator that ejects liquid, or a fine liquid ejected from a nozzle of a liquid ejecting head to generate fine particles ( It is suitable for a liquid jet printing apparatus that prints characters, images, and the like by forming dots) on a print medium.

  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.

On the other hand, when the actuator is a capacitive load such as a piezoelectric element, the capacitance of the filter composed of the smoothing filter and the actuator changes depending on the number of actuators to be driven, and the frequency when the capacitance of the filter changes. The characteristic changes and the waveform of the drive signal changes. Therefore, in the following Patent Document 2, a double feedback circuit is provided to suppress and prevent a change in the waveform of the drive signal accompanying a change in the number of actuators to be driven.
In addition to these, in Patent Document 3 below, when the drive signal to the actuator is power-amplified by the digital power amplifier circuit, considering that the fluctuation of the power supply voltage to the digital power amplifier circuit affects the voltage fluctuation of the drive signal, The modulation signal is corrected in accordance with the power supply voltage to the digital power amplifier circuit.

JP 2007-168172 A JP 2009-153272 A JP 2008-132765 A

By the way, when trying to perform the compensation using the feedback signal of the drive signal, that is, the output signal as in the liquid ejecting apparatus described in Patent Document 2, and the compensation using the divided signal according to the power supply voltage, Usually, a plurality of signal lines for individually extracting them are required. When processing is performed by digitization, an A / D converter is required for each signal line, which leads to an increase in circuit scale and cost.
The present invention has been developed by paying attention to these problems, and a power amplifier circuit and a liquid ejecting apparatus that can reduce the circuit scale and cost by reducing the number of signal lines and the number of A / D converters. An object of the present invention is to provide a liquid jet printing apparatus.

  In order to solve the above problems, a power amplifier circuit according to the present invention includes a digital power amplifier circuit that power-amplifies a modulation signal pulse-modulated by a modulation circuit to obtain a power amplification modulation signal, and smoothes the power amplification modulation signal. A smoothing filter that applies the output signal to the load, a superimposed signal in which a negative feedback signal in which the phase of the output signal of the smoothing filter is advanced, and a power supply voltage signal obtained by dividing the power supply voltage of the digital power amplifier circuit are superimposed A compensator for separating the superimposed signal into the power supply voltage signal and the negative feedback signal, and a difference compensator for inputting a difference signal between the input signal and the negative feedback signal to the modulation circuit, The separator is characterized in that the modulation signal modulated by the modulation circuit is corrected by inputting the power supply voltage signal to the modulation circuit.

  According to this power amplifier circuit, even when compensation by a negative feedback signal and compensation according to a power supply voltage are performed, the number of signal lines and the number of signal lines can be reduced by using a superimposed signal in which a power supply voltage signal and a negative feedback signal are superimposed. The number of A / D converters can be reduced, and thus the circuit scale and cost can be reduced. The superimposed signal is separated into a power supply voltage signal and a negative feedback signal, and a difference signal between the input signal and the negative feedback signal is obtained. By inputting to the modulation circuit and correcting the modulation signal according to the power supply voltage signal, compensation by the negative feedback signal and compensation according to the power supply voltage can be appropriately performed.

In addition, the separator includes a second smoothing filter that outputs the power supply voltage signal from the superimposed signal and a high-pass filter that outputs the negative feedback signal from the superimposed signal. .
According to this power amplifier circuit, it is possible to reliably separate the power supply voltage signal output through the low-pass filter and the negative feedback signal output through the high-pass filter from the superimposed signal.

The separator outputs the negative feedback signal by outputting a second smoothing filter that outputs the power supply voltage signal from the superimposed signal and a difference signal between the superimposed signal and the power supply voltage signal. And a differentiator.
According to this power amplifier circuit, the phase advance of the negative feedback signal can be avoided because there is no phase advance due to the high pass filter, compared to the case where the negative feedback signal is separated from the superimposed signal using a high pass filter. .

  The liquid ejecting apparatus of the present invention includes a modulation circuit that modulates a drive waveform signal used for driving an actuator to generate a modulation signal, and a digital power amplifier that amplifies the modulation signal to generate a power amplification modulation signal. A smoothing filter that smoothes the power amplification modulation signal to drive the actuator, a negative feedback signal that advances the phase of the driving signal, and a power supply voltage signal that divides the power supply voltage of the digital power amplification circuit A compensator for superimposing the superimposed signal, a separator for separating the superimposed signal into the power supply voltage signal and the negative feedback signal, and a difference signal between the drive waveform signal and the negative feedback signal as the modulation circuit The modulation circuit corrects the modulation signal according to the power supply voltage signal.

According to this liquid ejecting apparatus, even when compensation using a negative feedback signal and compensation according to a power supply voltage are performed, the number of signal lines and the number of signal lines can be increased by using a superimposed signal in which a power supply voltage signal and a negative feedback signal are superimposed. The number of A / D converters can be reduced, so that the circuit scale and cost can be reduced, and this superimposed signal is separated into a power supply voltage signal and a negative feedback signal, and a difference signal between the drive waveform signal and the negative feedback signal Is used as an input signal to the modulation circuit, and the modulation signal is corrected according to the power supply voltage signal, so that compensation by the negative feedback signal and compensation according to the power supply voltage can be appropriately performed.
Further, the liquid jet printing apparatus of the present invention is characterized by using the liquid jet apparatus.

1 is a schematic configuration front view showing an embodiment of a liquid jet printing apparatus using a power amplifier circuit and a liquid jet apparatus according to 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 a block diagram of the separator of FIG. It is a block diagram in the case of performing compensation by a negative feedback signal and compensation according to a power supply voltage in a conventional actuator drive circuit.

Next, as an embodiment of the power amplification circuit and the liquid ejecting apparatus of the present invention, the one used in the liquid ejecting printing apparatus will be described.
FIG. 1 is a schematic configuration diagram of a liquid jet printing apparatus according to the present embodiment. In FIG. 1, a print medium 1 is transported in the direction of an arrow from the left to the right in the drawing, and in a printing region in the middle of the transport. A line head type printing apparatus to be printed.

  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 and 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 separator described later, specifically, a negative feedback signal from the drive waveform signal WCOM An adder / subtractor 31 as a difference compensator for outputting a difference signal WCOMdef obtained by subtracting the difference signal, a modulation circuit 26 for pulse-modulating the difference signal WCOMdef from the adder / subtractor 31 and outputting a modulation signal PWM, and a modulation signal from the modulation circuit 26 A digital power amplifier circuit 28 that amplifies the PWM power and outputs a power amplification modulation signal APWM; The power amplification modulation signal APWM from the width circuit 28 is smoothed to be a smoothing filter 29 that outputs the drive signal COM, and a negative feedback signal CPSTS in which the phase of the drive signal COM is advanced, and the power supply voltage VDD of the digital power amplification circuit 28 Is divided into a power supply voltage signal VDDS, and a superimposing signal SPPS that superimposes both is output, and the superimposed signal SPPS from the compensator 32 is separated again into the power supply voltage signal VDDS and the negative feedback signal CPSTS, The separator 33 is configured to input a negative feedback signal CPSTS to the subtracting side of the adder / subtractor 31 and input a power supply voltage signal VDDS to the modulation circuit 26.

The drive waveform signal generation circuit 25 holds and outputs the drive waveform data DWCOM output from the CPU 62a 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, a triangular wave oscillator 34 that outputs a triangular wave signal with a predetermined frequency is compared with the triangular wave signal and the drive waveform signal WCOM. For example, a pulse duty modulation signal that becomes on-duty when the drive waveform signal WCOM is larger than the triangular wave signal. And a comparator 35 that outputs PWM.

  The modulation circuit 26, the drive waveform signal generation circuit 25 described above, and the adder / subtractor 31 serving as a difference compensator are substantially configured by arithmetic processing according to a program. The modulation circuit 26 includes a control unit 36 that performs arithmetic processing for adjusting the peak value, that is, the amplitude of the triangular wave signal by the triangular wave oscillator 34 in accordance with the power supply voltage signal VDDS from the separator 33. Yes. As described in Patent Document 3, when the power supply voltage VDD to the digital power amplifier circuit 28 changes, the voltage of the drive signal COM that is the final output also changes, and the desired printing accuracy cannot be obtained. Therefore, the power supply voltage signal VDDS corresponding to the power supply voltage VDD is used to adjust the amplitude of the triangular wave signal so that the original voltage of the drive signal COM is obtained. For the correction method by adjusting the amplitude of the triangular wave signal, refer to Patent Document 3. Further, as described in Patent Document 3, instead of adjusting the amplitude of the triangular wave signal, a method of correcting the value of the input signal to the modulation circuit 26 may be employed. 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. In addition, 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 filter composed of 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 outputs an analog superimposed signal SPPSA of an analog negative feedback signal CPSTSA and an analog power supply voltage signal VDDSA that is output from a common output terminal of a high-pass filter and a voltage divider, which will be described later. 38 and an A / D converter 37 that digitally converts the analog superimposed signal SPPSA from the analog compensation circuit 38 and outputs the superimposed signal SPPS. The analog compensation circuit 38 includes one capacitor C1 and one resistor R2. The analog compensation circuit 38 advances the phase of the drive signal COM and outputs an analog negative feedback signal CPSTSA, and one resistor R2 of the high-pass filter and the other one. The resistor R1 is combined with a voltage divider that outputs an analog power supply voltage signal VDDSA corresponding to the power supply voltage VDD. In the analog compensation circuit 38, the number of resistors can be reduced by sharing the resistor R2 of the high-pass filter and the resistor R2 of the voltage divider, and the analog superimposed signal SPPSA is digitized by one A / D converter 37. As a result, the number of A / D converters can be reduced.

  Separator 33 can take two forms, as shown in FIG. Among the digitally converted superimposed signal SPPS, the power supply voltage signal VDDS is a so-called low frequency component with little fluctuation, and the negative feedback signal CPSTS whose phase has been advanced is a so-called high frequency component with fast fluctuation. Therefore, as shown in FIG. 11 a, the separator 33 is a low-pass filter (LPF) 39 that passes the power supply voltage signal VDDS that is a low-frequency component of the superimposed signal SPPS (in order to distinguish it from the smoothing filter 29. And a high-pass filter (HPF) 40 that passes the negative feedback signal CPSTS that is a high-frequency component, and a power supply voltage that is also a low-frequency component of the superimposed signal VDDS, as shown in FIG. Two combinations of a low-pass filter 39 that passes the signal VDDS and an adder / subtractor (differential unit) 41 that outputs the negative feedback signal CPSTS by subtracting the power supply voltage signal VDDS that is the output of the low-pass filter 39 from the superimposed signal SPPS are considered. It is done. Among these, if the separator 33 is configured by a combination of the low-pass filter 39 and the high-pass filter 40, there is an advantage that the power supply voltage signal VDDS and the negative feedback signal CPSTS can be reliably separated. Further, if the separator 33 is configured by a combination of the low-pass filter 39 and the adder / subtractor 41, there is an advantage that the phase advance of the negative feedback signal CPSTS can be avoided. Incidentally, since the superimposed signal SPPS is digitized, both the low-pass filter 39 that passes the power supply voltage signal VDDS and the high-pass filter 40 that passes the negative feedback signal CPSTS subtract the power supply voltage signal VDDS from the superimposed signal SPPS and perform negative feedback. The adder / subtractor 41 that outputs the signal CPSTS can also be constructed by digitization, that is, arithmetic processing by a program.

  Here, in order to make the operation and effect of the present embodiment easier to understand, the digitized power supply voltage signal VDDS and the negative feedback signal CPSTS are individually extracted and input to the modulation circuit 26 and the adder / subtractor 31 individually. A comparative example is shown. In the comparative example, as shown in FIG. 12, naturally, two signal lines are required. For example, the signal line of the power supply voltage signal VDDS corresponding to the power supply voltage VDD to the digital power amplifier circuit 28 requires, for example, the voltage divider 501 by the resistors R1 and R2 and the A / D converter 502, and the drive signal COM For example, a high-pass filter 503 including a capacitor C3 and a resistor R3 and an A / D converter 504 are required for the signal line of the negative feedback signal CPSTS whose phase is advanced. These are all implemented, and the circuit scale and cost increase accordingly.

  In contrast to the comparative example, in the power amplifier circuit of the present embodiment, the modulation signal PWM pulse-modulated by the modulation circuit 26 is amplified by the digital power amplifier circuit 28, and the power amplification modulation signal APWM is smoothed by the smoothing filter 29. In addition, the output signal (drive signal COM) is applied to the load (actuator 22), and the compensator 32 advances the phase of the output signal (drive signal COM) of the smoothing filter 29 and the power supply voltage of the digital power amplifier circuit 28. The VDD is divided into a superimposed signal SPPS in which both are superimposed, the separator 33 separates the superimposed signal SPPS into the power supply voltage signal VDDS and the negative feedback signal CPSTS, and the adder / subtractor 31 as a difference compensator inputs the input signal. A difference signal WCOMdef between the (drive waveform signal WCOM) and the negative feedback signal CPSTS is input to the modulation circuit 26, and the modulation circuit 26 Since the modulation signal PWM is corrected according to the power supply voltage signal VDDS, the power supply voltage signal VDDS and the negative feedback signal CPSTS are compensated even when compensation using the negative feedback signal CPSTS and compensation according to the power supply voltage VDD are performed. The number of signal lines and the number of A / D converters can be reduced by using the superimposed signal SPPS on which is superimposed, so that the circuit scale and cost can be reduced, and compensation by the negative feedback signal CPSTS and the power supply voltage VDD can be achieved. Compensation according to this can be performed appropriately.

In addition, the separator 33 is configured by the low-pass filter 39 that outputs the power supply voltage signal VDDS from the superimposed signal SPPS of the compensator 32 and the high-pass filter 40 that outputs the negative feedback signal CPSTS from the superimposed signal SPPS of the compensator 32. The power supply voltage signal VDDS and the negative feedback signal CPSTS can be reliably separated from the superimposed signal SPPS.
Further, the low-pass filter 39 that outputs the power supply voltage signal VDDS from the superimposed signal SPPS of the compensator 32, and the differential operation between the superimposed signal SPPS of the compensator 32 and the power supply voltage signal VDDS of the low-pass filter 39 are performed, and the negative feedback signal CPSTS is obtained. The phase separator of the negative feedback signal CPSTS can be avoided by configuring the separator 33 with the adder / subtractor 41 serving as the differencer to be output.

In the liquid ejecting apparatus of the present embodiment, the drive waveform signal generation circuit 25 generates the drive waveform signal WCOM, and the signal from the drive waveform signal generation circuit 25 is pulse-modulated by the modulation circuit 26 to obtain the modulation signal PWM. The modulation signal PWM is amplified by the digital power amplifier circuit 28 to be a power amplification modulation signal APWM, and the power amplification modulation signal APWM is smoothed by a smoothing filter 29 to be a drive signal COM of the actuator 22. The phase of the drive signal COM is advanced and the power supply voltage VDD of the digital power amplifier circuit 28 is divided to obtain a superimposed signal SPPS in which both are superimposed. The separator 33 converts the superimposed signal SPPS into the power supply voltage signal VDDS and the negative feedback signal CPSTS. In the adder / subtractor 31 that is a differential compensator, the drive waveform signal WCOM and the negative feedback signal CPSTS Since the difference signal WCOMref is an input signal to the modulation circuit 26 and the modulation circuit 26 corrects the modulation signal PWM in accordance with the power supply voltage signal VDDS, compensation by the negative feedback signal CPSTS and compensation in accordance with the power supply voltage VDD Even when the power supply voltage signal VDDS and the negative feedback signal CPSTS are superimposed, the number of signal lines and the number of A / D converters can be reduced by using the superimposed signal SPPS in which the power supply voltage signal VDDS and the negative feedback signal CPSTS are superimposed. Therefore, compensation by the negative feedback signal CPSTS and compensation according to the power supply voltage VDD can be appropriately performed.
In the above-described embodiment, only the case where the power amplifier circuit and the liquid ejecting apparatus of the present invention are 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 type. The present invention can be similarly applied to a liquid jet printing 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, 25 is a drive waveform signal generation circuit, 26 is a modulation circuit, 28 is a digital power amplification circuit, 29 is a smoothing filter, 30 is a gate drive Circuit, 31 adder / subtractor, 32 compensator, 33 separator, 34 triangular wave oscillator, 35 comparison unit, 36 control unit, 37 A / D converter, 38 compensation circuit, 39 low pass filter, 40 Is a high-pass filter, 41 is an adder / subtracter, 62 is a control unit, and 65 is a head driver.

Claims (5)

A digital power amplifier circuit that amplifies the modulation signal pulse-modulated by the modulation circuit to obtain a power amplification modulation signal;
A smoothing filter that smoothes the power amplification modulation signal and applies an output signal to a load;
A compensator that forms a superimposed signal in which a negative feedback signal obtained by advancing the phase of the output signal of the smoothing filter and a power supply voltage signal obtained by dividing the power supply voltage of the digital power amplifier circuit;
A separator for separating the superimposed signal into the power supply voltage signal and the negative feedback signal;
A differential compensator for inputting a differential signal between the input signal and the negative feedback signal to the modulation circuit;
The power separator circuit corrects the modulation signal modulated by the modulation circuit by inputting the power supply voltage signal to the modulation circuit. The separator includes a second smoothing filter that outputs the power supply voltage signal from the superimposed signal;
The power amplifier circuit according to claim 1, further comprising a high-pass filter that outputs the negative feedback signal from the superimposed signal. The separator includes a second smoothing filter that outputs the power supply voltage signal from the superimposed signal;
The power amplifying circuit according to claim 1, further comprising: a differencer that outputs the negative feedback signal by outputting a difference signal between the superimposed signal and the power supply voltage signal. A modulation circuit for pulse-modulating a drive waveform signal used for driving an actuator,
A digital power amplifier circuit that amplifies the modulated signal to obtain a power amplified modulated signal;
A smoothing filter that smoothes the power amplification modulation signal to obtain a drive signal for the actuator;
A compensator that forms a superimposed signal in which a negative feedback signal in which the phase of the drive signal is advanced and a power supply voltage signal obtained by dividing the power supply voltage of the digital power amplifier circuit are superimposed;
A separator for separating the superimposed signal into the power supply voltage signal and the negative feedback signal;
A differential compensator that uses a differential signal between the drive waveform signal and the negative feedback signal as an input signal to the modulation circuit;
The liquid ejecting apparatus according to claim 1, wherein the modulation circuit corrects the modulation signal in accordance with the power supply voltage signal.   A liquid jet printing apparatus comprising the liquid jet apparatus according to claim 4.

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