JP2011025622A - Liquid jetting apparatus and liquid jetting type printer - Google Patents

Abstract

A liquid ejecting apparatus capable of obtaining a drive signal having an accurate waveform while saving power is provided.
A drive waveform signal WCOM is pulse-modulated by a modulation circuit 26, the modulated signal is power amplified by a digital power amplifier 28, and the power amplified modulated signal is smoothed by a smoothing filter 29 to output a digital drive signal COM_D. At the same time, the drive waveform signal WCOM is subjected to predetermined delay processing, the delayed drive waveform signal WCOM_A is converted into an analog signal, the power is amplified by the analog power amplifier 33, and the analog drive signal COM_A is added (mixed) to the digital drive signal COM_D. And supplied to the actuator 22 as a drive signal COM. The higher the ratio of the analog drive signal COM_A with better waveform accuracy, the higher the image quality, while the higher the ratio of the digital drive signal COM_D, the higher the power efficiency.
[Selection] Figure 6

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid by applying a drive signal to an actuator, for example, by ejecting a minute liquid from a nozzle of a liquid ejecting head to form fine particles (dots) on a print medium, The present invention is suitable for a liquid jet printing apparatus that prints predetermined 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 potential, the drive waveform signal that becomes the reference of the drive signal must be amplified by a power amplifier. Therefore, in Patent Document 1 below, a digital power amplifier that has an extremely small power loss and can be downsized as compared with an analog power amplifier is used, and a drive waveform signal is pulse-modulated by a modulation circuit to obtain a modulation signal. Is amplified by a digital power amplifier to obtain a power amplification modulation signal, and the power amplification modulation signal is smoothed by a smoothing filter to obtain a drive signal.

JP 2007-168172 A

However, in the liquid ejecting apparatus described in Patent Document 1, since the power amplification modulation signal amplified by the digital power amplifier is smoothed by the smoothing filter, the output frequency characteristic is narrow, and the target drive signal is obtained. On the other hand, there is a problem that it is difficult to obtain a drive signal having an accurate waveform.
The present invention has been developed paying attention to these problems, and is a liquid ejecting apparatus capable of obtaining a drive signal having an accurate waveform while saving power, and liquid ejecting printing using the liquid ejecting apparatus The object is to provide an apparatus.

In order to solve the above problems, a liquid ejecting apparatus of the present invention includes a drive waveform signal generation circuit that generates a drive waveform signal, a modulation circuit that performs pulse modulation on the drive waveform signal, and a modulation signal. A digital power amplifier that amplifies the power to obtain a power amplification modulation signal, a smoothing filter that smoothes the power amplification modulation signal to obtain a digital drive signal, and performs a predetermined delay process on the drive waveform signal to obtain a delay drive waveform signal An output drive waveform signal processing unit; a DA converter that analog-converts the delayed drive waveform signal into an analog delay drive waveform signal; an analog power amplifier that amplifies the analog delay drive waveform signal to generate an analog drive signal; And adding means for adding the analog drive signal to the digital drive signal and supplying the analog drive signal as a drive signal to the actuator. It is an feature.
According to this liquid ejecting apparatus, it is possible to obtain a drive signal having an accurate waveform by adding the analog drive signal from the analog power amplifier while saving power by using a digital power amplifier.

The drive waveform signal processing unit performs delay control of the drive waveform signal in accordance with the number of actuators to be driven.
According to this liquid ejecting apparatus, even when the actuator is a capacitive load and the number of driven actuators fluctuates, driving is performed in consideration of the phase delay of the drive signal that changes according to the number of driven actuators. By performing delay control of the waveform signal, it is possible to obtain a drive signal with an accurate waveform while saving power.

Further, the ratio of the digital drive signal and the analog drive signal can be adjusted according to the required waveform accuracy of the drive signal.
According to this liquid ejecting apparatus, it is possible to adjust such that the mixing ratio of the analog drive signal is increased when priority is given to image quality, and the mixing ratio of the analog drive signal is decreased when priority is given to power efficiency.
Further, the adding means includes a mixing ratio adjusting means for adjusting a mixing ratio of the analog driving signal to the digital driving signal.
According to this liquid ejecting apparatus, the mixing ratio of the analog drive signal to the digital drive signal can be easily adjusted.

1 is a front view of a schematic configuration showing an embodiment of a liquid jet printing apparatus using a liquid jet apparatus 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 of FIG. 6. It is a block diagram of the smoothing filter of FIG. FIG. 7 is a block diagram of a drive waveform signal processing unit in FIG. 6. FIG. 7 is a block diagram of the analog power amplifier of FIG. 6. It is explanatory drawing of an analog drive signal and a digital drive signal. It is an output characteristic figure of an analog power amplifier and a digital power amplifier. It is a frequency characteristic figure which changes with the number of actuators driven. It is a characteristic explanatory view of image quality priority and speed priority. It is explanatory drawing of the drive signal by the drive circuit of FIG.

Next, as an embodiment of the liquid ejecting apparatus of the present invention, one used in a 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 potential changes around an intermediate potential 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.

  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. The switching controller includes a shift 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 that temporarily stores data of the shift register 211. 212 and a level shifter 213 for connecting the drive signal COM 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 drive pulse selection data signal SI & SP is sequentially input to the shift register 211, and the storage area is sequentially shifted from the first stage to the subsequent stage according to the input pulse of the clock signal SCK. The latch circuit 212 latches each output signal of the shift register 211 by the input latch signal LAT after the drive pulse selection data SI & SP for the number of nozzles is stored in the shift 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 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. Accordingly, 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. In addition, after the drive pulse selection data SI & SP of the shift register 211 is stored in the latch circuit 212, the next print information is input to the shift register 211, and the stored data of the latch circuit 212 is sequentially updated in accordance with the liquid ejection timing. . 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). The drive waveform signal generation circuit 25 to be generated, the digital power amplifier 12 that outputs the digital drive signal COM_D from the drive waveform signal WCOM generated by the drive waveform signal generation circuit 25, and the analog drive signal COM_A from the drive waveform signal WCOM. An analog power amplifying unit 13 for output and an adder 14 for adding the analog drive signal COM_A to the digital drive signal COM_D and outputting the drive signal COM are provided. The drive waveform signal generation circuit 25 converts the drive waveform data DWCOM output from the CPU 62a into a voltage signal, and outputs the hold signal for a predetermined sampling period.

  The digital power amplifier 12 includes a modulation circuit 26 that performs pulse modulation on the drive waveform signal WCOM, a digital power amplifier 28 that amplifies the modulation signal pulse-modulated by the modulation circuit 26, and power amplified by the digital power amplifier 28. And a smoothing filter 29 that smoothes the amplified modulated signal and outputs it as a digital drive signal COM_D. The analog power amplifying unit 13 delays the drive waveform signal WCOM and outputs a delayed drive waveform signal WCOM_A, a DA converter 32 that converts the delayed drive waveform signal WCOM_A into analog, an analog An analog power amplifier 33 that amplifies the converted analog delay drive waveform signal AWCOM_A and outputs an analog drive signal COM_A is provided.

  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. For the modulation circuit 26, a known pulse modulation circuit such as a pulse density modulation (PDM) circuit can be used. In any case, the modulation circuit 26 can be configured by arithmetic processing by a program.

  As shown in FIG. 8, the digital power amplifier 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 signal from the modulation circuit 26. A gate drive circuit 30 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 PWM is configured. In the digital power amplifier 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 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 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. Therefore, the loss of the digital power amplifier 28 is extremely small, and a switching element such as a small MOSFET can be used.

As the smoothing filter 29, as shown in FIG. 9, a secondary filter including one resistor R, one capacitor C, and one coil L was used. The smoothing filter 29 attenuates and removes the modulation frequency generated in the modulation circuit 26, that is, the frequency component of pulse modulation, and outputs a digital drive signal COM_D.
As shown in FIG. 10, the drive waveform signal processing unit 31 includes a drive waveform signal delay unit 36 that performs a delay process for a predetermined time on the drive waveform signal and outputs a delayed drive waveform signal WCOM_A, and a drive waveform signal delay unit 36. A delay time control unit 37 that controls the delay time is provided. The delay time control unit 37 obtains the number of actuators 22 driven from the drive pulse selection data SI & SP as will be described later, and sets the delay time according to the number of actuators 22.

  As shown in FIG. 11, the analog power amplifier 33 is configured by push-pull connection of two transistors Tr1 and Tr2, one of which has the collector of the NPN transistor Tr1 connected to the constant voltage power supply VDD, and the emitter output terminal. The base is connected to one output of the base drive circuit 38. The emitter of the other PNP transistor Tr2 is connected to the output terminal, the collector is grounded, and the base is connected to the other output Q2 of the base drive circuit 38. The analog power amplifier 33 linearly drives the two transistors Tr1 and Tr2 that are push-pull connected to amplify the analog delay drive waveform signal AWCOM_A and output an analog drive signal COM_A.

  The adder 14 adds (mixes) the analog drive signal COM_A to the digital drive signal COM_D at a predetermined ratio, which will be described later, to create a drive signal COM, which is generated via the selection switch 201 of the liquid ejecting head 2 described above. To the actuator 22. The adder 14 includes a variable resistor as a mixing ratio adjusting unit that adjusts the mixing ratio of the analog driving signal COM_A to the digital driving signal COM_D. This variable resistor is interposed on the analog drive signal COM_A side. For example, as the resistance value of the variable resistor increases, the amount of power supplied from the analog power amplifier 33 decreases, and the drive signal COM ( The waveform accuracy of the drive pulse PCOM) approaches the level of the digital drive signal COM_D alone, but the power efficiency is increased. On the other hand, the smaller the resistance value of the variable resistor, the closer to the analog drive signal COM_A, and in the case of a liquid jet printing apparatus, high image quality can be realized, but the power efficiency decreases. Instead of this variable resistor, a switching element such as a MOSFET is used, and an image quality selection signal is output from the control circuit side according to the required image quality, and the gate voltage of the switching element is adjusted based on the signal to perform switching. The trade-off between image quality and power consumption may be adjusted by varying the on-resistance of the element.

  FIG. 12 shows the analog drive signal COM_A and the digital drive signal COM_D when the drive waveform signal COM is not subjected to delay processing. A smoothing filter 29 composed of a low-pass filter is interposed in the digital power amplifier 12. A transfer function of a secondary low-pass filter composed of a resistor R, a coil L, and a capacitor C is expressed by the following equation (1). For this reason, a phase lag occurs in the digital drive signal COM_D with respect to the analog drive signal COM_A. Further, compared with the analog drive signal COM_A, the digital drive signal COM_D is rounded with the corners of the drive signal removed. This is because the output flat portion of the digital power amplifier is narrower than the analog power amplifier, as shown in FIG. Since the digital power amplifier 12 uses the above-described low-pass filter to remove the output in the high frequency band, the output flat portion is narrower than the analog power amplifier 13.

  The piezoelectric element that is the actuator 22 is a capacitive element, and each actuator 22 has a predetermined capacitance. Since the actuator 22 driven to eject the liquid is connected to the drive circuit by the selection switch 201, the capacitance of the capacitor of the smoothing filter 29 formed of a low-pass filter depends on the number of actuators 22 to be driven. Change. For this reason, as shown in FIG. 14, if the number of actuators 22 to be driven increases (in the figure, the load capacity is large), the amount of phase delay increases. The number of actuators 22 to be driven can be obtained from the drive pulse selection data SI & SP. If the number of actuators 22 to be driven is known, the phase delay amount of the digital drive signal COM_D can also be obtained. Therefore, the delay time control unit 37 obtains the number of actuators 22 driven from the drive pulse selection data SI & SP, and sets the delay time applied to the drive waveform signal WCOM according to the obtained number of drive actuators 22. In other words, in the present embodiment, the analog drive signal COM_A that has essentially no delay or a small delay is caused to have a delay equivalent to the digital drive signal COM_D, and the analog drive signal COM_A that has caused this delay is changed to the digital drive signal COM_D. Addition (mixing) creates the drive signal COM.

  Further, in the present embodiment, as shown in FIG. 15, for example, the ratio of the analog drive signal COM_A mixed with the digital drive signal COM_D is adjusted depending on whether the image quality is improved or the power efficiency is improved. For example, as shown in FIG. 16, the drive signal having a rounded waveform with respect to the target drive signal target value COM_t is a digital drive signal COM_D, and the analog drive signal COM_D whose phase is adjusted is added to this ( What is mixed) is the drive signal COM output from the drive circuit of FIG. As the addition (mixing) ratio of the analog drive signal COM_D is larger, the drive signal COM is closer to the drive signal target value COM_t, which is preferable for improving the image quality. However, the power consumption is larger than when the waveform is formed with the digital power amplifier 28 alone (it is sufficiently smaller than when the waveform is formed with the analog power amplifier 33 alone, and power saving is possible). When the image quality is not required, the power efficiency can be further improved by reducing the addition (mixing) ratio of the analog drive signal COM_A.

  Thus, in the liquid ejecting apparatus of the present embodiment, the drive waveform signal WCOM is pulse-modulated to output the modulation signal PWM, the modulation signal is power-amplified by the digital power amplifier 28, and the power amplification modulation signal APWM is output, The power amplification modulation signal APWM is smoothed to output a digital drive signal COM_D, and the drive waveform signal WCOM is subjected to a predetermined delay process to output a delay drive waveform signal WCOM_A. The analog delayed analog delay drive waveform signal ACOM_A Is amplified by the analog power amplifier 33 to output an analog drive signal COM_A, and the adder 14 as an adding means adds the analog drive signal COM_A to the digital drive signal COM_D and supplies it to the actuator 22 as the drive signal COM. Therefore, use the digital power amplifier 28 While realizing power saving, adding the analog drive signal COM_A from the analog power amplifier 33 (mixture), it is possible to obtain a drive signal COM exact waveform.

  Further, since the delay control of the drive waveform signal WCOM is performed in accordance with the number of actuators 22 to be driven, the actuator 22 is a capacitive load and is driven even when the number of actuators 22 to be driven fluctuates. By performing the delay control of the drive waveform signal WCOM in consideration of the phase delay of the drive signal COM that changes in accordance with the number of actuators 22, the drive signal COM having an accurate waveform can be obtained while saving power.

Further, since the ratio of the analog drive signal COM_A mixed with the digital drive signal COM_D can be adjusted according to the required waveform accuracy of the drive signal COM, the ratio of the analog drive signal COM_A can be set when priority is given to image quality. In the case of increasing the power efficiency and giving priority to the power efficiency, the adjustment of decreasing the ratio of the analog drive signal COM_A becomes possible.
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. 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, 24 is an inverse filter circuit, 25 is a drive waveform signal generation circuit, 26 is a modulation circuit, 28 is a digital power amplifier, and 29 is a smoothing filter , 30 is a gate drive circuit, 31 is a drive waveform signal processing unit, 32 is a DA converter, 33 is an analog power amplifier, 34 is a triangular wave oscillator, 35 is a comparison unit, 36 is a drive waveform signal delay unit, and 37 is a delay time control unit. , 38 is a base drive circuit, 65 is a head driver

Claims (3)

A drive waveform signal generating circuit for generating a drive waveform signal;
A modulation circuit that modulates the drive waveform signal by pulse modulation;
A digital power amplifier that amplifies the modulated signal to obtain a power amplified modulated signal;
A smoothing filter that smoothes the power amplification modulation signal to form a digital drive signal;
A drive waveform signal processing unit that applies a predetermined delay process to the drive waveform signal and outputs a delayed drive waveform signal;
A DA converter that analog-converts the delay drive waveform signal into an analog delay drive waveform signal; and
An analog power amplifier that amplifies the analog delay drive waveform signal to obtain an analog drive signal; and
A liquid ejecting apparatus comprising: an adding unit that adds the analog drive signal to the digital drive signal and supplies the analog drive signal to the actuator as a drive signal.   The liquid ejecting apparatus according to claim 1, wherein the drive waveform signal processing unit performs delay control of the drive waveform signal according to the number of actuators to be driven.   A liquid jet printing apparatus comprising the liquid jet apparatus according to claim 1.

Images