JP2013052689A - Driving circuit, liquid injection device, and printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid injection device reducing a voltage difference between a power supply voltage and a driving signal, and reducing loss or heat generation.SOLUTION: The liquid injection device includes: a plurality of nozzles provided in a liquid injection head 2; a nozzle actuator 22 provided corresponding to the nozzles; and a driving circuit 20 applying a driving signal COM to the nozzle actuator 22. The liquid injection device includes a power supply voltage adjusting circuit 21 adjusting power supply voltages VHV, VLV to the driving signal COM to a predetermined wave voltage based on a reference signal Vcnt obtained from the driving signal COM or signal in a stage for generating the driving signal. This reduces the voltage difference between: the driving signal COM charging the nozzle actuator 22 including a charging/discharging actuator or the driving signal COM discharging the nozzle actuator 22; and the power supply voltage.

Description

  The present invention relates to a liquid ejecting apparatus configured to print predetermined characters, images, and the like by ejecting minute liquid from a plurality of nozzles and forming fine particles (dots) on a print medium. .

Inkjet printers, which are one of such printing devices, are generally inexpensive and can easily obtain high-quality color printed matter. Therefore, with the spread of personal computers and digital cameras, not only offices but also general users. It has become widespread.
Among such liquid ejecting printing apparatuses, those that place a liquid ejecting head in which liquid ejecting nozzles are formed on a moving body called a carriage and move in a direction crossing the transport direction of the print medium are generally referred to as “multi-pass printing”. Called "device". On the other hand, what is capable of printing in a so-called one pass by arranging a long liquid jet head in a direction crossing the conveyance direction of the printing medium is generally called a “line head type printing apparatus”. In such a liquid ejecting apparatus, a plurality of nozzles for ejecting liquid are formed on the liquid ejecting head, and nozzle actuators such as piezoelectric elements are disposed on each nozzle, and each nozzle actuator of the liquid ejecting head is detected from a waveform voltage signal. In some cases, the liquid is ejected from the corresponding nozzle toward the print medium by being driven by the drive signal.

  As power amplification of such a drive signal, for example, in the liquid ejecting apparatus described in Patent Document 1 below, a drive waveform signal serving as a reference of a signal for controlling the drive of a nozzle actuator is converted into an analog signal by an analog conversion circuit, and the analog The drive waveform signal is amplified by an analog power amplifier circuit. In the liquid ejecting apparatus described in Patent Document 2 below, the drive waveform signal is converted into an analog signal by an analog conversion circuit, the analog drive waveform signal is pulse-modulated, and the modulated signal is amplified by a digital power amplifier circuit. I am doing so.

JP-A-5-77456 JP-A-11-204850

  By the way, since the piezoelectric element used as the nozzle actuator of the inkjet printer is a charge / discharge actuator, the drive signal charges the charge / discharge actuator or discharges the charge from the charge / discharge actuator. Although the digital power amplifier of the liquid ejecting apparatus described in Patent Document 2 has an advantage of low loss and heat generation, a smoothing filter for smoothing the drive signal is interposed on the output side of the digital power amplifier. In general, the smoothing filter is composed of a low-pass filter, and the electrostatic capacity of the charge / discharge actuator is connected to this low-pass filter, so the waveform of the drive signal changes according to the number of connected nozzle actuators. Resulting in. On the other hand, since the analog power amplifier does not have a low-pass filter on the output side, the waveform of the drive signal does not change even if the number of connected nozzle actuators changes.

However, an analog power amplifier for charging a charge to a charge / discharge actuator or discharging a charge from the charge / discharge actuator is composed of a charge transistor and a discharge transistor connected in a push-pull manner. Since the drive signal is amplified by so-called linear drive using voltage, the voltage difference between the power supply voltage and the drive signal for charging the charge / discharge actuator is also the voltage between the drive signal discharged from the charge / discharge actuator and the ground voltage. The difference is also large, resulting in high power consumption. Since most of this power consumption is consumed as heat, the drive circuit that generates each drive signal requires a large transistor or heat sink, which greatly increases the mounting area on the circuit board. Is a major obstacle in layout.
An object of the present invention is to provide a liquid ejecting apparatus that can reduce a voltage difference between a power supply voltage and a drive signal and can reduce loss and heat generation.

  In order to solve the above problem, a liquid ejecting apparatus according to a first aspect of the present invention applies a drive signal to a plurality of nozzles provided in a liquid ejecting head, a nozzle actuator provided corresponding to the nozzle, and the nozzle actuator. A liquid ejecting apparatus including a drive circuit, wherein a power supply voltage adjustment for adjusting a power supply voltage to the drive signal to a preset waveform voltage based on a reference signal obtained from the drive signal or a signal at a generation stage thereof A circuit is provided.

The power supply voltage to the drive signal of the present invention does not simply indicate the upper limit value of the power supply voltage necessary for generating the drive signal, but the charging source power supply voltage of the nozzle actuator composed of a charge / discharge actuator such as a piezoelectric element, The power supply voltage including the discharge destination power supply voltage is shown, and specifically includes the terminal voltage of the push-pull connected transistor pair of the power amplifier circuit.
According to this liquid ejecting apparatus, it is possible to reduce a voltage difference between a drive signal for charging a nozzle actuator composed of a charge / discharge actuator and a drive signal for discharging the nozzle actuator and a power supply voltage, thereby reducing loss and heat generation. It becomes possible.

  In the liquid ejecting apparatus according to the aspect of the invention, the drive circuit may be generated by a drive waveform signal generation circuit that generates a drive waveform signal that serves as a reference of a signal that controls driving of the nozzle actuator, and the drive waveform signal generation circuit. An analog conversion circuit for converting the drive waveform signal into analog, a power amplification circuit for power-amplifying the analog drive waveform signal analog-converted by the analog conversion circuit, and a pre-driver circuit for driving the power amplification circuit The reference signal is generated based on the output signal of any one of these circuits.

According to this liquid ejecting apparatus, it is possible to improve the accuracy of the drive signal and further reduce loss and heat generation.
In the liquid ejecting apparatus of the invention, the power supply voltage adjustment circuit includes a plurality of power supply voltage generation circuits or voltage adjustment circuits that generate or adjust a plurality of power supply voltages, and the plurality of power supply voltage generation circuits or voltage adjustment circuits. And a power supply voltage selection circuit for selecting an output voltage.

According to this liquid ejecting apparatus, it is possible to further reduce the loss and heat generation by further reducing the voltage difference between the drive signal and the power supply voltage.
In the liquid ejecting apparatus of the invention, the power supply voltage generation circuit is a DC voltage power supply circuit, or the voltage adjustment circuit is a DC voltage adjustment circuit.
According to this liquid ejecting apparatus, it is easy to implement the power supply voltage adjustment circuit.

In the liquid ejecting apparatus according to the aspect of the invention, the power supply voltage generation circuit may be an AC voltage power supply circuit, or the voltage adjustment circuit may be an AC voltage adjustment circuit.
According to this liquid ejecting apparatus, it is easy to implement the power supply voltage adjustment circuit.
In the liquid ejecting apparatus according to the aspect of the invention, the power supply voltage adjustment circuit may be configured by a power supply circuit that can boost the power supply voltage by a bootstrap circuit, and controls the boosting of the power supply voltage by the bootstrap circuit by the reference signal. It is characterized by this.

According to this liquid ejecting apparatus, it is easy to implement the power supply voltage adjustment circuit, and it is possible to obtain a high power supply voltage to the drive signal using a lower power supply voltage.
In the liquid ejecting apparatus of the invention, a backflow preventing diode is disposed on the output side of the bootstrap circuit.
According to this liquid ejecting apparatus, the waveform of the drive signal can be ensured.

According to the liquid ejecting apparatus of the present invention, it is possible to reduce a voltage difference between a drive signal for charging a nozzle actuator composed of a charge / discharge actuator or a drive signal for discharging the nozzle actuator and a power supply voltage, thereby reducing loss and invention. The effect which can be done is produced.
Further, according to the liquid ejecting apparatus of the present invention, it is easy to implement the power supply voltage adjustment circuit, and it is possible to obtain a high power supply voltage to the drive signal using a lower power supply voltage.

1 is a schematic front view illustrating a first embodiment of a line head type printing apparatus to which a liquid ejecting apparatus of the invention is applied. FIG. 2 is a plan view of the vicinity of a liquid ejecting head used in the liquid ejecting apparatus of FIG. 1. It is a block block diagram of the control apparatus of the printing apparatus of FIG. FIG. 6 is an explanatory diagram of a drive signal for driving a nozzle actuator in each liquid ejecting head. It is a block diagram of a switching controller. FIG. 2 is a block diagram in the vicinity of a built drive circuit in the head driver of FIG. 1. It is a block diagram of the drive circuit of FIG. FIG. 8 is a block diagram of the power amplifier circuit of FIG. 7. FIG. 7 is a block diagram of the power supply voltage adjustment circuit of FIG. 6. 2 is a waveform chart of a power supply voltage by the liquid ejecting apparatus in FIG. 1. 6 is a waveform chart of a power supply voltage showing a second embodiment of the liquid ejecting apparatus of the invention. FIG. 10 is a block diagram of a power supply voltage adjustment circuit showing a third embodiment of the liquid ejecting apparatus of the invention. 13 is a waveform chart of a power supply voltage by the liquid ejecting apparatus of FIG. FIG. 10 is a block diagram of a power supply voltage adjustment circuit showing a fourth embodiment of the liquid ejecting apparatus of the invention. 15 is a waveform chart of a power supply voltage by the liquid ejecting apparatus of FIG. FIG. 10 is a block diagram of a power supply voltage adjustment circuit showing a fifth embodiment of the liquid ejecting apparatus of the invention. 17 is a waveform chart of a power supply voltage by the liquid ejecting apparatus of FIG. FIG. 17 is a block diagram of a different example of the power supply voltage adjustment circuit of FIG. 16. FIG. 10 is a block diagram in the vicinity of a drive circuit showing a sixth embodiment of a liquid ejecting apparatus of the invention. FIG. 20 is a block diagram of the drive circuit of FIG. 19. It is a block diagram of the power amplifier circuit of FIG. FIG. 20 is a block diagram of the power supply voltage adjustment circuit of FIG. 19. 20 is a waveform chart of a power supply voltage by the liquid ejecting apparatus in FIG. 19. 10 is a waveform chart of a power supply voltage showing a seventh embodiment of the liquid ejecting apparatus of the invention. FIG. 10 is a block diagram of a power supply voltage adjustment circuit showing an eighth embodiment of a liquid ejecting apparatus of the invention. FIG. 26 is a waveform chart of a power supply voltage by the liquid ejecting apparatus of FIG. 25. FIG. 10 is a block diagram of a power supply voltage adjustment circuit showing a ninth embodiment of the liquid ejecting apparatus of the invention. It is a waveform chart of the power supply voltage by the liquid ejecting apparatus of FIG. FIG. 10 is a block diagram of a power supply voltage adjustment circuit showing a tenth embodiment of a liquid ejecting apparatus of the invention. FIG. 30 is a waveform chart of a power supply voltage by the liquid ejecting apparatus of FIG. 29. FIG. FIG. 30 is a block diagram of a different example of the power supply voltage adjustment circuit of FIG. 29.

Next, a first embodiment of the printing apparatus of the present invention will be described.
FIG. 1 is a schematic configuration diagram of a printing apparatus according to the present embodiment. In the drawing, a print medium 1 is conveyed in the direction of an arrow from the left to the right in the figure, and is printed in a printing area in the middle of the conveyance. It is a line head type printing apparatus.

  Reference numeral 2 in FIG. 1 denotes six 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. FIG. 2 is a plan view of the vicinity of the liquid ejecting head 2. These liquid jet heads 2 are arranged in a staggered manner as shown in the figure, for example. A large number of nozzles are formed in the inner portion of the inner square in the drawing showing the lowermost surface of each liquid ejecting head 2, and this surface is called a nozzle surface. Accordingly, a line head that extends over the entire length in the direction intersecting the transport direction of the print medium 1 is formed by all the liquid jet heads 2 arranged in a staggered manner. 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. Further, in the liquid jet head 2 of the present embodiment, the nozzles are formed in a staggered pattern on the nozzle surface. Thus, by opening the nozzles in a staggered manner, the distance in the direction intersecting the print medium conveyance direction between the nearest nozzles, that is, the so-called pixel interval can be shortened.

  For example, liquids such as yellow (Y), magenta (M), cyan (C), and black (K) inks are supplied to the liquid ejecting head 2 from liquid tanks of respective colors (not shown) through liquid supply tubes. Supplied. Each liquid ejecting head 2 is formed with a plurality of nozzles in a direction orthogonal to the transport direction of the print medium 1 (that is, the nozzle row direction), and a necessary amount of liquid is ejected from these nozzles to a necessary location at the same time. As a result, minute dots are formed on the print medium 1. By performing this for each color, it is possible to perform printing by so-called one-pass only by passing the print medium 1 conveyed by the conveyance unit 4 once.

  As a method of ejecting liquid from each nozzle of the liquid ejecting head, 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 a nozzle actuator, the diaphragm in the cavity is displaced to cause a pressure change in the cavity, and a droplet is ejected from the nozzle by the pressure change. . The droplet ejection amount can be adjusted by adjusting the peak value of the drive signal and the voltage increase / decrease slope. A piezoelectric element used in the piezo method is a capacitive load, and charges are charged by a drive signal or charges are discharged to the drive signal side. Further, the present invention can be similarly applied to a liquid ejecting method 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.

  A control device for controlling itself is provided in the printing apparatus. For example, as shown in FIG. 3, the control device prints on a print medium by controlling a printing device, a paper feeding device, and the like based on print data input from a host computer 60 such as a personal computer or a digital camera. The processing is performed. An input interface 61 for receiving print data input from the host computer 60; a control unit 62 configured by, for example, a microcomputer that executes print processing based on the print data input from the input interface 61; A paper feed roller motor driver 63 for driving and controlling the paper feed roller motor 17 connected to the paper feed roller 5, a head driver 65 for driving and controlling the liquid ejecting head 2, and an electric motor connected to the drive roller 8. An electric motor driver 66 that drives and controls the motor 7 and an interface 67 that connects the drivers 63, 65, 66 to the external paper feed roller motor 17, the liquid ejecting head 2, and the electric motor 7 are configured.

  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 interface 61, the CPU 62a executes a predetermined process on the print data to determine which nozzle of any liquid ejecting head 2. Nozzle selection data (driving signal selection data) indicating how much liquid is to be ejected or how much liquid is to be ejected, and based on this print data, driving signal selection data, and input data from various sensors, each driver Control signals are output to 63, 65, 66. A drive signal for driving the actuator is output from each driver 63, 65, 66, and the paper feed roller motor 17 and the electric motor 7 are operated to feed, convey and discharge the print medium 1, and print. A printing process on the medium 1 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 from the control device of the printing apparatus of the present embodiment to the liquid ejecting head 2 and drives a nozzle actuator 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 output to each liquid ejecting head 2 from a drive circuit constructed in the head driver 65, and a drive pulse PCOM as a unit drive signal for ejecting liquid by driving the nozzle actuator. They are connected in time series. The rising portion of each drive pulse PCOM is a stage in which the volume of the cavity (pressure chamber) communicating with the nozzle is expanded and liquid is drawn (it can be said that the meniscus is drawn in view of the liquid ejection surface), and the fall of the drive pulse PCOM The portion is a stage in which the volume of the cavity is reduced to extrude the liquid (which can be said to extrude the meniscus in view of the liquid ejection surface), and as a result of extruding the liquid, droplets are ejected from the nozzle.

  By variously changing the voltage increase / decrease slope and peak value of the driving pulse PCOM composed of this voltage trapezoidal wave, the liquid drawing amount and drawing speed, the liquid pushing amount and the pushing speed can be changed. It is possible to obtain dots of different sizes by changing the amount of injection. 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, and droplets are ejected or a plurality of drive pulses PCOM are selected and the actuator is selected. In this way, dots of various sizes can be obtained by ejecting droplets a plurality of times. That is, if a plurality of droplets land on the same position before the liquid dries, it is substantially the same as ejecting a large droplet, and the size of the dot can be increased. By combining such techniques, it is possible to increase the number of gradations. The mechanism for selecting the drive signal by the drive signal selection data SI & SP can be realized in the form described in, for example, Japanese Patent Application Laid-Open No. 2003-1824. Note that the driving pulse PCOM1 at the left end in FIG. This is called microvibration, and is used, for example, to suppress or prevent thickening of the nozzle without ejecting droplets.

  In addition to the drive signal COM, each liquid ejecting head 2 selects a nozzle to be ejected based on print data as a control signal from the control device in FIG. 3 and outputs it to a drive signal COM for a nozzle actuator such as a piezoelectric element. The drive signal selection data SI & SP for determining the connection timing, the latch signal LAT for connecting the drive signal COM and the nozzle actuator of the liquid ejecting head 2 based on the drive signal selection data SI & SP after the nozzle selection data is inputted to all the nozzles, and A clock signal SCK for transmitting the channel signal CH and the drive signal selection data SI & SP as a serial signal to the liquid jet head 2 is input. Hereinafter, the minimum unit of the drive signal for driving the nozzle actuator 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 the switching controller constructed in each liquid jet head 2 in order to supply the drive signal COM (drive pulse PCOM) to the nozzle actuator 22. This switching controller temporarily stores the shift register 211 that stores drive signal selection data SI & SP for designating the nozzle actuator 22 such as a piezoelectric element corresponding to the nozzle that should eject liquid, and the data of the shift register 211. The level shifter 213 is configured to connect the drive signal COM to the nozzle actuator 22 such as a piezo element by converting the level of the output of the latch circuit 212 and the output of the latch circuit 212 to the selection switch 201.

  The drive signal 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 in accordance with 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 signal 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, a nozzle actuator 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 signal selection data SI & SP. In addition, after the drive signal 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 in 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 nozzle actuators, such as a piezoelectric element. Further, according to the selection switch 201, even after the nozzle actuator such as a piezoelectric element is disconnected from the drive signal COM (drive pulse PCOM), the input voltage of the nozzle actuator 22 is maintained at the voltage just before the disconnection.

  FIG. 6 shows an outline of the drive circuit 20 constructed in the head driver 65. The drive circuit 20 outputs the drive signal COM to the nozzle actuator 22 as described above. Similarly, in the head driver 65, the drive circuit 20, specifically, the power supply voltage to the drive signal COM is supplied. The power source voltage adjusting circuit 21 for adjusting the charging power is constructed. In this embodiment and the following embodiments, the power source voltage adjusting circuit 21 supplies a charging source power source voltage to the nozzle actuator 22 composed of a piezoelectric element which is a charge / discharge actuator. Adjust VHV. Based on the reference signal Vcnt obtained from the drive circuit 20, the power supply voltage adjustment circuit 21 adjusts the charging source power supply voltage to the drive signal COM to a predetermined waveform voltage set in advance. The reference signal Vcnt is, for example, a signal that compares the drive signal COM shown in FIG. 4 with a predetermined voltage set in advance and becomes high level when the drive signal COM is larger than the predetermined voltage, and low level when the drive signal COM is smaller. Become.

  FIG. 7 shows a specific configuration of the drive circuit 20. The drive circuits 20 in FIGS. 7a to 7d have the same configuration, but the output source of the reference signal Vcnt described above is different. The drive circuit 20 generates a drive waveform signal WCOM that generates a digital data drive waveform signal WCOM that serves as a reference for controlling the drive of the nozzle actuator 22, and the drive waveform signal WCOM generated by the drive waveform signal generation circuit 23. A D / A conversion circuit (analog conversion circuit) 24 that performs analog conversion, a power amplification circuit 26 that amplifies the analog drive waveform signal AWCOM analog-converted by the D / A conversion circuit 24, and a power amplification circuit 26 are driven. The pre-driver circuit 25 is configured.

  The drive waveform signal generation circuit 23 reads drive waveform data stored in a memory (not shown), converts it into a voltage signal, holds it for a predetermined sampling period, and outputs a drive waveform signal WCOM of digital data. The D / A conversion circuit 24 uses a general digital-analog conversion circuit, which converts the digital data drive waveform signal WCOM into an analog drive waveform signal AWCOM. As will be described later, the pre-driver circuit 25 controls the base voltage of each transistor of the power amplifier circuit 26 composed of push-pull connected transistor pairs, and rises, for example, when the number of connected nozzle actuators changes. The base current of the charging transistor is suppressed. As the pre-driver circuit 25, for example, the one described in Japanese Patent Application Laid-Open No. 2004-306434 previously proposed by the present applicant can be applied. For example, as shown in FIG. 8, the power amplifying circuit 26 is configured by push-pull connection of a charging transistor Q1 and a discharging transistor Q2, and the collector of one NPN-type charging transistor Q1 has the power supply voltage adjustment. The charging source power supply voltage VHV is supplied from the circuit 21, the emitter is connected to the input side of the selection switch 201, and the base is connected to one output of the pre-driver circuit 25. The emitter of the other PNP type discharge transistor Q2 is connected to the input side of the selection switch 201, the collector is grounded, and the base is connected to the other output of the pre-driver circuit 25. In this transistor pair, one charging transistor Q1 supplies a charge from the charging source power supply voltage VHV to the nozzle actuator 22 that is a capacitive load through the selection switch 201 with a voltage waveform corresponding to the drive signal COM. That is, charging is performed, and the other discharging transistor Q2 discharges the electric charge of the nozzle actuator 22 which is a capacitive load through the selection switch 201 with a voltage waveform corresponding to the driving signal COM.

  7a, the reference signal Vcnt is extracted from the drive waveform signal WCOM output from the drive waveform signal generation circuit 23. In FIG. 7b, the reference signal Vcnt is output from the analog drive waveform signal AWCOM output from the D / A conversion circuit 24. 7c, the reference signal Vcnt is extracted from the base voltage control signal output from the pre-driver circuit 25, and the reference signal Vcnt is extracted from the drive signal COM output from the power amplifier circuit 26 in FIG. 7d. As the output position of the reference signal Vcnt is closer to the drive waveform signal generation circuit 23, the power supply voltage described later can be switched at a timing corresponding to the original drive signal COM (or drive waveform signal WCOM). The closer to, the more the power supply voltage can be switched at the timing when the actual drive signal COM is fed back.

  FIG. 9 shows a specific configuration example of the power supply voltage adjustment circuit 21. FIG. 9a includes n power supply voltage generation circuits 27 for generating a predetermined power supply voltage set in advance, from first to nth. FIG. 9B shows a first voltage adjustment circuit 28 that adjusts the power supply voltage generated by one power supply voltage generation circuit 27 to a power supply voltage having a preset waveform. n power supply voltages having different waveforms are output from each of the power supply voltage selection circuits 29. The power supply voltage selection circuit 29 generates power supply voltages having different waveforms generated by the first to nth power supply voltage generation circuits 27 or the first power supply voltages. The power supply voltages having different waveforms output from the 1st to nth voltage adjustment circuits 28 are selected based on the reference signal Vcnt, and the selected waveform voltage is supplied as the power supply voltage of the drive signal COM of the drive circuit 20. The power supply voltage generation circuit 27 and the voltage adjustment circuit 28 perform substantially the same function. For example, when the power supply voltage that is the basis of the power supply voltage generation circuit 27 and the voltage adjustment circuit 28 is a direct current voltage, an existing DC / DC converter is used. In the case where the main power supply voltage of the DC / AC converter is an AC voltage, an existing AC / DC converter or AC / AC converter can be applied.

  FIG. 10 is a voltage waveform chart of the charging source power supply voltage VHV of the present embodiment. The charging source power supply voltage VHV is obtained by switching, for example, two DC power supply voltages output from the power supply voltage generation circuit 27 and the voltage adjustment circuit 28 of FIG. 9 with a reference signal Vcnt. When Vcnt is at a low level, the DC power supply voltage VDL having a small voltage value is selected, and when the reference signal Vcnt is at a high level, the DC power supply voltage VDH having a large voltage value is selected.

  For example, the power supply voltage to the conventional drive signal COM is constant at the DC power supply voltage VDH having a large voltage value shown in FIG. Since this power supply voltage is applied as a charging source power supply voltage for charging the nozzle actuator 22 via the charging transistor Q1, the drive signal is charged when the nozzle actuator 22 is charged, that is, when the drive signal COM rises. The voltage difference from COM results in loss or heat generation. In the present embodiment, since the voltage difference between the drive signal COM and the charging source power supply voltage VHV can be reduced, loss and heat generation can be reduced. As will be described in detail later, the discharge destination power supply voltage VLV discharged from the nozzle actuator 22 is adjusted using the same configuration, and the voltage difference between the drive signal COM and the discharge destination power supply voltage VLV is reduced. By doing so, it is possible to further reduce loss and heat generation accordingly.

  As described above, according to the liquid ejecting apparatus of the present embodiment, the plurality of nozzles provided in the liquid ejecting head 2, the nozzle actuators 22 provided corresponding to the nozzles, and the drive signals to the nozzle actuators 22 are provided. The liquid ejecting apparatus includes a drive circuit 20 that applies COM, and the power supply voltage VHV to the drive signal COM is set in advance based on the drive signal COM or a reference signal Vcnt obtained from a signal at the generation stage thereof. Since the power supply voltage adjustment circuit 21 for adjusting the waveform voltage is provided, the voltage difference between the power supply voltage and the drive signal COM that charges the nozzle actuator 22 that is a charge / discharge actuator and the drive signal COM that discharges the nozzle actuator 22 is obtained. It can be reduced, and loss and heat generation can be reduced.

  The drive circuit 20 also generates a drive waveform signal WCOM that generates a drive waveform signal WCOM that serves as a reference for a signal that controls the drive of the nozzle actuator 22, and the drive waveform signal WCOM generated by the drive waveform signal generation circuit 23. An analog conversion circuit (D / A conversion circuit) 24 that performs analog conversion, a power amplification circuit 26 that amplifies the analog drive waveform signal AWCOM analog-converted by the analog conversion circuit 24, and a pre-drive for driving the power amplification circuit 26 The driver circuit 25 is configured to generate the reference signal Vcnt based on the output signal of any one of these circuits, so that the accuracy of the drive signal COM can be improved and the power consumption can be further reduced. .

The power supply voltage adjustment circuit 21 selects a plurality of power supply voltage generation circuits 27 or voltage adjustment circuits 28 that generate or adjust a plurality of power supply voltages, and the output voltages of the plurality of power supply voltage generation circuits 27 or voltage adjustment circuits 28. Since the power supply voltage selection circuit 29 is configured to be configured, the voltage difference between the drive signal COM and the power supply voltage VHV can be further reduced to further reduce power consumption.
Further, since the power supply voltage generation circuit 27 is a DC voltage power supply circuit or the voltage adjustment circuit 28 is a DC voltage adjustment circuit, the power supply voltage adjustment circuit 21 can be easily implemented.

Next, a second embodiment of the liquid ejecting apparatus of the invention will be described with reference to FIG. The schematic configuration, control device, drive signal, switching controller, drive circuit, and power supply voltage adjustment circuit of the liquid ejecting apparatus of the present embodiment are all the same as those in FIGS. 1 to 9 of the first embodiment. FIG. 11 is a voltage waveform chart of the charging source power supply voltage VHV of the present embodiment. The charging source power supply voltage VHV is obtained by switching the DC power supply voltage and the AC power supply voltage output from, for example, the power supply voltage generation circuit 27 and the voltage adjustment circuit 28 of FIG. 9 with a reference signal Vcnt. When the reference signal Vcnt is at a low level, the DC power supply voltage VD is selected, and when the reference signal Vcnt is at a high level, the AC power supply voltage VA is selected. Also in the present embodiment, the voltage difference between the drive signal COM and the charging source power supply voltage VHV can be reduced, so that loss and heat generation can be reduced.
Thus, according to the liquid ejecting apparatus of the present embodiment, in addition to the effects of the first embodiment, the power supply voltage generation circuit 27 is an AC voltage power supply circuit or the voltage adjustment circuit 28 is an AC voltage adjustment circuit. Therefore, it is easy to implement the power supply voltage adjustment circuit 21.

  Next, a third embodiment of the liquid ejecting apparatus of the invention will be described with reference to FIGS. The schematic configuration, control device, drive signal, switching controller, and drive circuit of the liquid ejecting apparatus of the present embodiment are all the same as those in FIGS. 1 to 8 of the first embodiment. FIG. 12 shows a configuration of the power supply voltage adjustment circuit 21 of the present embodiment, and a bootstrap circuit 30 is provided. The bootstrap circuit 30 is configured by push-pull connection of a charging transistor Q3 that charges the capacitor C3 and a discharging transistor Q4 that discharges the charge of the capacitor C3, and is connected to the collector of one NPN-type charging transistor Q3. Is supplied with the original power supply voltage Vdd, the emitter is connected to the capacitor C3, and the base is connected to one output of the bootstrap pre-driver circuit 31. The emitter of the other PNP type discharge transistor Q4 is connected to the capacitor C3, the collector is grounded, and the base is connected to the other output of the bootstrap pre-driver circuit 31. Between the original power supply voltage Vdd and the output of the power supply voltage adjustment circuit 21, a backflow prevention diode D3 is interposed.

  The bootstrap circuit 30 charges the capacitor C3 while the discharging transistor Q4 is off and the charging transistor Q3 is on. After the capacitor C3 is charged, the charging power supply voltage VHV is largely generated by discharging from the capacitor C3. The power supply voltage Vdd can be doubled. FIG. 13 is a voltage waveform chart of the charging source power supply voltage VHV of the present embodiment. This charging source power supply voltage VHV is obtained by switching the base currents of the transistors Q3 and Q4 of the bootstrap circuit 30 with a reference signal Vcnt. Specifically, when the reference signal Vcnt is at a low level, the charging transistor Q3 is turned on. The charging source power supply voltage VHV is set to the original power supply voltage Vdd, and the charging transistor Q4 is turned on when the reference signal Vcnt is at the high level, thereby turning the charging source power supply voltage VHV to 2 of the original power supply voltage Vdd. It is a double value. Also in the present embodiment, the voltage difference between the drive signal COM and the charging source power supply voltage VHV can be reduced, so that loss and heat generation can be reduced.

  As described above, according to the liquid ejecting apparatus of the present embodiment, in addition to the effects of the first embodiment, the power supply voltage adjustment circuit 21 is configured by a power supply circuit capable of boosting the power supply voltage VHV by the bootstrap circuit 30, In addition, since the boosting of the power supply voltage VHV by the bootstrap circuit 30 is controlled by the reference signal Vcnt, the power supply voltage adjustment circuit 21 can be easily implemented, and the lower original power supply voltage Vdd is used to drive the drive signal COM. A high power supply voltage VHV can be obtained.

  Next, a fourth embodiment of the liquid ejecting apparatus of the invention will be described with reference to FIGS. The schematic configuration, control device, drive signal, switching controller, and drive circuit of the liquid ejecting apparatus of the present embodiment are all the same as those in FIGS. 1 to 8 of the first embodiment. FIG. 14 shows the power supply voltage adjustment circuit 21 of the present embodiment. The power supply voltage adjustment circuit 21 of the present embodiment is similar to that of the third embodiment shown in FIG. 12, and the same components are denoted by the same reference numerals, and detailed description thereof is omitted. In the power supply voltage adjustment circuit 21 of the present embodiment, a backflow prevention diode D31 is further provided on the output side of the bootstrap circuit 30.

The voltage waveform chart of the charging source power supply voltage VHV of this embodiment shown in FIG. 15 is basically the same as the voltage waveform chart of FIG. 15 of the third embodiment, but for example, on the output side of the bootstrap circuit 30 In the absence of the diode D31, for example, when the charging source power supply voltage VHV falls at a timing earlier than a predetermined timing as shown by a two-dot chain line, the voltage of the drive signal COM suddenly increases according to the charging source power supply voltage VHV. The drive signal COM changes in accordance with the charging source power supply voltage VHV so as to decrease (specifically, charge is discharged from the nozzle actuator 22 which is a charge / discharge actuator). On the other hand, if a diode D31 for backflow prevention is provided on the output side of the bootstrap circuit 30 as in the present embodiment, discharge of electric charges from the nozzle actuator 22 that is a charge / discharge actuator is prevented. Thus, it is possible to suppress and prevent a change in the drive signal COM.
As described above, according to the liquid ejecting apparatus of the present invention of this embodiment, the backflow prevention diode D31 is provided on the output side of the bootstrap circuit 30, so that the waveform of the drive signal COM can be ensured.

  Next, a fifth embodiment of the liquid ejecting apparatus of the invention will be described with reference to FIGS. The schematic configuration, control device, drive signal, switching controller, and drive circuit of the liquid ejecting apparatus of the present embodiment are all the same as those in FIGS. 1 to 8 of the first embodiment. FIG. 16 shows the power supply voltage adjustment circuit 21 of the present embodiment. The power supply voltage adjustment circuit 21 of the present embodiment is similar to that of the third embodiment shown in FIG. 12, and the same components are denoted by the same reference numerals, and detailed description thereof is omitted. In the power supply voltage adjustment circuit 21 of the present embodiment, another bootstrap circuit 32 is provided on the output side of the bootstrap circuit 30 of the third embodiment. Of these, if the output-side bootstrap circuit 32 is a front-stage bootstrap circuit and the input-side bootstrap circuit 30 is a rear-stage bootstrap circuit, the front-stage bootstrap circuit 32 is also the same as the rear-stage bootstrap circuit 30. The charge transistor Q5 that charges the capacitor C5 and the discharge transistor Q6 that discharges the charge of the capacitor C5 are connected by a push-pull connection. The output terminal of the strap circuit 30 is supplied, the emitter is connected to the capacitor C5, and the base is connected to one output of the pre-bootstrap pre-driver circuit 33. The emitter of the other PNP type discharge transistor Q6 is connected to the capacitor C5, the collector is connected to the emitter of the discharge transistor Q4 of the bootstrap circuit 30 in the subsequent stage, and the base is the other of the pre-driver circuit 31 for the bootstrap in the previous stage. Connected to the output. Between the output terminal of the bootstrap circuit 30 in the subsequent stage and the output of the power supply voltage adjustment circuit 21, a backflow prevention diode D5 is interposed.

  In the bootstrap circuit 30 at the subsequent stage, the output voltage is twice the power supply voltage Vdd when the discharging transistor Q4 is off and the charging transistor Q3 is on. When Q6 is turned off and the charging transistor Q5 is turned on, the charging source power supply voltage VHV can be made three times as large as the main power source voltage Vdd. FIG. 17 is a voltage waveform chart of the charging source power supply voltage VHV of the present embodiment. The charging source power supply voltage VHV switches the base currents of the transistors Q5 and Q6 of the bootstrap circuit 32 in the previous stage with the first reference signal Vcnt1, and the base currents of the transistors Q3 and Q4 of the bootstrap circuit 30 in the subsequent stage to the second reference signal. Specifically, when the first reference signal Vcnt1 and the second reference signal Vcnt2 are both at the low level, the charging transistor Q5 of the bootstrap circuit 32 in the preceding stage and the bootstrap circuit 30 in the subsequent stage are switched. The charging transistor Q3 is turned off to set the charging source power supply voltage VHV to the main power supply voltage Vdd. When only the second reference signal Vcnt2 is at the high level, only the charging transistor Q4 of the bootstrap circuit 30 in the subsequent stage is turned on. The charging source power supply voltage VHV When the first reference signal Vcnt1 and the second reference signal Vcnt2 are both at a high level, the charging transistor Q5 of the preceding bootstrap circuit 32 and the charging transistor Q3 of the subsequent bootstrap circuit 30 By turning on both of the two, the charging source power supply voltage VHV is set to be three times the original power supply voltage Vdd. Also in the present embodiment, the voltage difference between the drive signal COM and the charging source power supply voltage VHV can be reduced, so that loss and heat generation can be reduced.

As described above, according to the liquid ejecting apparatus of the present embodiment, in addition to the effects of the third embodiment, it is possible to obtain the high power supply voltage VHV to the drive signal COM using the lower original power supply voltage Vdd. It becomes possible.
As in the fourth embodiment, a backflow prevention diode D31 may be disposed on the output side of the bootstrap circuit 32 preceding the power supply voltage adjustment circuit 21 of the fifth embodiment. Further, as shown in FIG. 18, the backflow prevention diodes D3 and D5 may be connected in parallel to the original power supply voltage Vdd. When the backflow prevention diodes D3 and D5 are directly connected as shown in FIG. 16, the input voltage to the bootstrap circuit 32 at the preceding stage is reduced by the voltage drop caused by the backflow prevention diode D3 on the input side. Although the voltage drop due to the diode is very small, the input voltage to the bootstrap circuit 32 in the previous stage is reduced by that voltage drop. To avoid this, as shown in FIG. The prevention diodes D3 and D5 may be connected to the main power supply voltage Vdd in parallel.

  Next, a sixth embodiment of the liquid ejecting apparatus of the invention will be described. FIG. 19 shows a schematic configuration of the drive circuit 20 of the present embodiment. In all of the embodiments after this embodiment, not only the charging source power supply voltage VHV for charging the nozzle actuator 22 through the power amplifier 26 but also the charge from the nozzle actuator 22 through the power amplifier 26 is used. The discharge destination power supply voltage VLV for discharging is also adjusted.

  FIG. 20 shows a specific configuration of the drive circuit 20. Since the drive circuit 20 of this embodiment is the same as that of the first embodiment, the same reference numerals are given to the same components, and the detailed description thereof is omitted. 20a to 20d, the output source of the reference signal Vcnt is different. 20a, the reference signal Vcnt is extracted from the drive waveform signal WCOM output from the drive waveform signal generation circuit 23. In FIG. 20b, the reference signal Vcnt is extracted from the analog drive waveform signal AWCOM output from the D / A conversion circuit 24. 20c, the reference signal Vcnt is extracted from the base voltage control signal output from the pre-driver circuit 25. In FIG. 20d, the reference signal Vcnt is extracted from the drive signal COM output from the power amplifier circuit 26. The effect of the difference in the output position of the reference signal Vcnt is the same as that in the first embodiment. As described above, the power amplifier circuit 26 shown in FIG. 21 is supplied with the charge source power supply voltage VHV and the discharge destination power supply voltage VLV adjusted by the power supply voltage adjustment circuit 21.

  FIG. 22 shows a specific configuration example of the power supply voltage adjustment circuit 21. FIG. 22a includes n power supply voltage generation circuits 27 for generating a predetermined power supply voltage set in advance, from first to nth. FIG. 22B shows a first voltage adjustment circuit 28 for adjusting a power supply voltage generated by one power supply voltage generation circuit 27 to a power supply voltage having a preset waveform. n power supply voltages having different waveforms are output from each of the power supply voltage selection circuits 29. The power supply voltage selection circuit 29 generates power supply voltages having different waveforms generated by the first to nth power supply voltage generation circuits 27 or the first power supply voltages. The power supply voltages having different waveforms output from the 1st to nth voltage adjustment circuits 28 are selected based on the reference signal Vcnt, and the selected waveform voltage is supplied as the power supply voltage of the drive signal COM of the drive circuit 20. In the present embodiment, the functions of the power supply voltage generation circuit 27 and the voltage adjustment circuit 28 are the same except that the power supply voltage generation circuit 27 not only generates or adjusts the charge source power supply voltage VHV but also generates or adjusts the discharge destination power supply voltage VLV. It is the same as that of one embodiment.

  FIG. 23 is a voltage waveform chart of the charge source power supply voltage VHV and the discharge destination power supply voltage VLV of the present embodiment. Among them, the charging source power supply voltage VHV is obtained by switching two DC power supply voltages output from the power source voltage generation circuit 27 and the voltage adjustment circuit 28 of FIG. 22 with the charging source reference signal VcntH. When the charging source reference signal VcntH is at a low level, the charging source DC power supply voltage VDHL having a small voltage value is selected, and when the charging source reference signal VcntH is at a high level, the charging source DC power supply voltage having a large voltage value is selected. When VDHH is selected and the discharge destination reference signal VcntL is at a low level, the discharge destination DC power supply voltage VDLH having a small voltage value is selected, and when the discharge destination reference signal VcntL is at a high level, a discharge destination having a large voltage value is selected. DC power supply voltage VDLL (= 0V) is selected.

  For example, as for the power supply voltage to the conventional drive signal COM, the discharge destination power supply voltage VLV is constant at the ground voltage (= 0V). Since this ground voltage is a voltage value for discharging from the nozzle actuator 22 via the discharge transistor Q2, a voltage difference from the drive signal COM at the time of discharge from the nozzle actuator 22, that is, at the fall of the drive signal COM. Loss or heat generation. In the present embodiment, not only the voltage difference between the drive signal COM and the charging source power supply voltage VHV but also the voltage difference between the drive signal COM and the discharge destination power supply voltage VLV can be reduced, thereby reducing loss and heat generation. It becomes possible to do.

  As described above, according to the liquid ejecting apparatus of the present embodiment, in addition to the effects of the first embodiment, a plurality of nozzles provided in the liquid ejecting head 2 and nozzle actuators provided corresponding to these nozzles 22 and a drive circuit 20 that applies a drive signal COM to the nozzle actuators 22, and the drive signal is based on the drive signal COM or a reference signal Vcnt obtained from a signal at the generation stage thereof. By providing the power supply voltage adjustment circuit 21 that adjusts the power supply voltages VHV and VLV to COM to preset waveform voltages, the drive signal COM for charging the nozzle actuator 22 composed of a charge / discharge actuator and the nozzle actuator 22 are The voltage difference between the drive signal COM to be discharged and the power supply voltage can be reduced, and loss and heat generation are reduced. It becomes possible.

  The power supply voltage adjustment circuit 21 selects a plurality of power supply voltage generation circuits 27 or voltage adjustment circuits 28 that generate or adjust a plurality of power supply voltages, and the output voltages of the plurality of power supply voltage generation circuits 27 or voltage adjustment circuits 28. Since the power supply voltage selection circuit 29 is provided, the voltage difference between the drive signal COM and the power supply voltages VHV and VLV can be further reduced to further reduce power consumption.

  Next, a seventh embodiment of the liquid ejecting apparatus of the invention will be described with reference to FIG. The schematic configuration, control device, drive signal, and switching controller of the liquid ejecting apparatus of this embodiment are all the same as those in FIGS. 1 to 5 of the first embodiment, and the drive circuit and the power supply voltage adjustment circuit are It is the same as that of FIGS. 19-22 of 6 embodiment. FIG. 24 is a voltage waveform chart of the charge source power supply voltage VHV and the discharge destination power supply voltage VLV of the present embodiment. The charging source power supply voltage VHV and the discharge destination power supply voltage VLV are obtained by switching the DC power supply voltage and the AC power supply voltage output from the power supply voltage generation circuit 27 and the voltage adjustment circuit 28 of FIG. 22 with reference signals VcntH and VcntL, for example. Specifically, the charging source DC power supply voltage VDH is selected when the charging source reference signal VcntH is at a low level, and the charging source AC power supply voltage VAH is selected when the charging source reference signal VcntH is at a high level. When the discharge destination reference signal VcntL is at a low level, the discharge destination DC power supply voltage VDL is selected. When the discharge destination reference signal VcntL is at a high level, the discharge destination AC power supply voltage VAL is selected. It is a thing. Also in the present embodiment, the voltage difference between the drive signal COM and the charging source power supply voltage VHV can be reduced, so that loss and heat generation can be reduced.

  Next, an eighth embodiment of the liquid ejecting apparatus of the invention will be described with reference to FIGS. The schematic configuration, the control device, the drive signal, and the switching controller of the liquid ejecting apparatus of this embodiment are all the same as those in FIGS. 1 to 5 of the first embodiment, and the drive circuit is the same as that of the sixth embodiment. 19 to 21 are the same. FIG. 25 shows the configuration of the power supply voltage adjustment circuit 21 of the present embodiment, which is the same as that shown in FIG. 12 of the third embodiment, except that the main power supply voltage of both ends of the capacitor C3. Charging source power supply potential VHV is output from the end connected to Vdd, and discharging destination power supply potential VLV is output from the end connected to the emitter of charging transistor Q3.

  FIG. 26 is a voltage waveform chart of the charge source power supply voltage VHV and the discharge destination power supply voltage VLV of the present embodiment. The charge source power supply voltage VHV and the discharge destination power supply voltage VLV are obtained by switching the base currents of the transistors Q3 and Q4 of the bootstrap circuit 30 with a reference signal Vcnt. Specifically, the reference signal Vcnt is at a low level. Sometimes the charging transistor Q3 is turned off, the charging source power supply voltage VHV is set to the original power supply voltage Vdd, the discharge destination power supply voltage VLV is set to 0V, and the charging transistor Q4 is turned on when the reference signal Vcnt is at the high level. Thus, the charging source power supply voltage VHV is set to twice the original power supply voltage Vdd, and the discharge destination power supply voltage VLV is set to the original power supply voltage Vdd. Also in the present embodiment, the voltage difference between the drive signal COM and the charging source power supply voltage VHV and the discharging destination power supply voltage VLV can be reduced, so that loss and heat generation can be reduced.

  Next, a ninth embodiment of the liquid ejecting apparatus of the invention will be described with reference to FIGS. The schematic configuration, control device, drive signal, and switching controller of the liquid ejecting apparatus of this embodiment are all the same as those in FIGS. 1 to 5 of the first embodiment, and the drive circuit is the same as that of the sixth embodiment. 19 to 21 are the same. FIG. 27 shows the power supply voltage adjustment circuit 21 of the present embodiment. The power supply voltage adjustment circuit 21 of this embodiment is similar to that of FIG. 12 of the eighth embodiment, and the same reference numerals are given to the same components, and detailed description thereof is omitted. In the power supply voltage adjustment circuit 21 of this embodiment, diodes D31 and D32 for backflow prevention are further provided on the output side of the bootstrap circuit 30.

  The voltage waveform chart of the charge source power supply voltage VHV and the discharge destination power supply voltage VLV shown in FIG. 28 is basically the same as the voltage waveform chart of FIG. 15 of the eighth embodiment, but for example, the bootstrap When there is no diode D31 on the output side of the circuit 30, for example, when the charging source power supply voltage VHV falls at a timing earlier than a predetermined timing as shown by a two-dot chain line, a drive signal is generated according to the charging source power supply voltage VHV. The voltage of COM drops rapidly (specifically, the electric charge is discharged from the nozzle actuator 22 which is a charge / discharge actuator). For example, the discharge destination power supply voltage VLV is indicated by a two-dot chain line. When falling at a ming earlier than the predetermined timing, the voltage of the drive signal COM increases rapidly according to the discharge destination power supply voltage VLV. (Specifically, the charge-discharge type charge to the nozzle actuator 22 is an actuator from being charged) As such, the drive signal COM is changed in accordance with the charging based on the power supply voltage VHV and discharge destination supply voltage VLV. On the other hand, if the backflow prevention diodes D31 and D32 are provided on the output side of the bootstrap circuit 30 as in this embodiment, the discharge of charges from the nozzle actuator 22 which is a charge / discharge type actuator and The charge of the nozzle actuator 22 can be prevented from being charged, and thereby the change in the drive signal COM can be suppressed and prevented.

  Next, a tenth embodiment of the liquid ejecting apparatus of the invention will be described with reference to FIGS. 29 and 30. FIG. The schematic configuration, the control device, the drive signal, and the switching controller of the liquid ejecting apparatus of this embodiment are all the same as those in FIGS. 1 to 5 of the first embodiment, and the drive circuit is the same as that of the sixth embodiment. 19 to 21 are the same. FIG. 29 shows the power supply voltage adjustment circuit 21 of the present embodiment. The power supply voltage adjustment circuit 21 of this embodiment is the same as that shown in FIG. 16 of the fifth embodiment, but is connected to the main power supply voltage Vdd at both ends of the capacitor C5 of the bootstrap circuit 32 in the previous stage. The charging source power supply potential VHV is output from the end that is connected, and the discharge destination power supply potential VLV is output from the end connected to the emitter of the charging transistor Q5.

  FIG. 30 is a voltage waveform chart of the charge source power supply voltage VHV and the discharge destination power supply voltage VLV of the present embodiment. The charging source power supply voltage VHV switches the base currents of the transistors Q5 and Q6 of the bootstrap circuit 32 in the previous stage with the first reference signal Vcnt1, and the base currents of the transistors Q3 and Q4 of the bootstrap circuit 30 in the subsequent stage to the second reference signal. Specifically, when the first reference signal Vcnt1 and the second reference signal Vcnt2 are both at the low level, the charging transistor Q5 of the bootstrap circuit 32 in the preceding stage and the bootstrap circuit 30 in the subsequent stage are switched. The charging transistor Q3 is turned off, the charging source power supply voltage VHV is set to the main power supply voltage Vdd, the discharge destination power supply voltage VLV is set to 0V, and only the second reference signal Vcnt2 is at the high level, the bootstrap circuit in the subsequent stage Turn on only 30 charging transistor Q4 Thus, the charging source power supply voltage VHV is set to a double value of the original power supply voltage Vdd and the discharge destination power supply voltage VLV is set to the main power supply voltage Vdd, and both the first reference signal Vcnt1 and the second reference signal Vcnt2 are at the high level. By turning on both the charging transistor Q5 of the bootstrap circuit 32 in the preceding stage and the charging transistor Q3 of the bootstrap circuit 30 in the subsequent stage, the charging source power supply voltage VHV is three times the original power supply voltage Vdd. And the discharge destination power supply voltage VLV is twice the original power supply voltage Vdd. Also in the present embodiment, the voltage difference between the drive signal COM and the charging source power supply voltage VHV can be reduced, so that loss and heat generation can be reduced.

As described above, according to the liquid ejecting apparatus of the present embodiment, in addition to the effects of the sixth embodiment, the power supply voltage adjustment circuit 21 includes the power supply voltage VHV by the front bootstrap circuit 32 and the rear bootstrap circuit 30. The power supply voltage adjustment circuit 21 is easy to implement because the power supply circuit is configured to be capable of boosting VLV and the boosting of the power supply voltages VHV and VLV by the bootstrap circuits 30 and 32 is controlled by the reference signals Vcnt1 and Vcnt2. At the same time, it is possible to obtain high power supply voltages VHV and VLV for the drive signal COM using a lower original power supply voltage Vdd.
As described above, according to the liquid ejecting apparatus of the present embodiment, in addition to the effects of the eighth embodiment, the higher power supply voltages VHV and VLV to the drive signal COM using the lower original power supply voltage Vdd are used. Can be obtained.

  As in the fourth embodiment, backflow prevention diodes D31 and D32 may be disposed on the output side of the bootstrap circuit 32 in the previous stage of the power supply voltage adjustment circuit 21 of the tenth embodiment. Further, as shown in FIG. 31, the backflow prevention diodes D3 and D5 may be connected in parallel to the original power supply voltage Vdd. When the backflow prevention diodes D3 and D5 are directly connected as shown in FIG. 29, the input voltage to the bootstrap circuit 32 in the previous stage is reduced by the voltage drop caused by the backflow prevention diode D3 on the input side. Although the voltage drop due to the diode is negligible, the input voltage to the bootstrap circuit 32 in the preceding stage is reduced by that voltage drop. In order to avoid this, as shown in FIG. The prevention diodes D3 and D5 may be connected to the main power supply voltage Vdd in parallel.

  In each of the above embodiments, only the charging source power supply voltage VHV to the nozzle actuator 22 that is a charge / discharge actuator is adjusted, or only both the charging source power supply voltage VHV and the discharge destination power supply voltage VLV are adjusted. As described above, even if only the discharge destination power supply voltage VLV is adjusted by the same configuration, the voltage difference between the drive signal COM and the discharge destination power supply voltage VLV is reduced, thereby reducing loss and heat generation. It becomes.

  In the above embodiment, only the example in which the liquid ejecting apparatus of the present invention is applied to a so-called line head type printing apparatus has been described in detail. However, the liquid ejecting apparatus of the present invention is not limited to a multi-pass type printing apparatus. It is applicable to a type of printing apparatus. Moreover, each part which comprises the liquid ejecting apparatus of this invention may be replaced with the thing of the arbitrary structures which can exhibit the same function, and the other arbitrary structures may be added.

  In the above embodiment, the liquid ejecting apparatus of the present invention is embodied in an ink jet printing apparatus. However, the present invention is not limited to this, and liquids other than ink (functional material particles are dispersed in addition to liquids). It is also possible to embody the present invention in a liquid ejecting apparatus that ejects or ejects a fluid other than a liquid (including a fluid such as a liquid or gel) or a fluid other than a liquid (such as a solid that can be ejected by flowing as a fluid). 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 printing medium, 2 is a liquid ejecting head, 3 is a paper feeding unit, 4 is a conveying unit, 6 is a conveying belt, 7 is an electric motor, 8 is a driving roller, 9 is a driven roller, 10 is a paper discharging unit, and 11 is Fixed plate, 17 is a paper feed roller motor, 20 is a drive circuit, 21 is a power supply voltage adjustment circuit, 22 is a nozzle actuator, 23 is a drive waveform signal generation circuit, 24 is a D / A conversion circuit, 25 is a pre-driver circuit, 26 Is a power amplifier circuit, 27 is a power supply voltage generation circuit, 28 is a voltage adjustment circuit, 29 is a power supply voltage selection circuit, 30 and 32 are bootstrap circuits, and 31 and 32 are bootstrap pre-drivers.

Claims (7)

  A liquid ejecting apparatus comprising: a plurality of nozzles provided in a liquid ejecting head; a nozzle actuator provided corresponding to the nozzle; and a drive circuit that applies a drive signal to the nozzle actuator; A liquid ejecting apparatus comprising: a power supply voltage adjusting circuit that adjusts a power supply voltage to the drive signal to a preset waveform voltage based on a reference signal obtained from a signal at the generation stage.   The drive circuit includes a drive waveform signal generation circuit that generates a drive waveform signal that serves as a reference of a signal that controls the drive of the nozzle actuator, and an analog conversion that converts the drive waveform signal generated by the drive waveform signal generation circuit into an analog signal A circuit, a power amplifier circuit that amplifies the analog drive waveform signal analog-converted by the analog converter circuit, and a pre-driver circuit for driving the power amplifier circuit. The liquid ejecting apparatus according to claim 1, wherein the reference signal is generated on the basis of the output signal.   The power supply voltage adjustment circuit includes a plurality of power supply voltage generation circuits or voltage adjustment circuits for generating or adjusting a plurality of power supply voltages, and a power supply voltage selection circuit for selecting output voltages of the plurality of power supply voltage generation circuits or voltage adjustment circuits. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is configured to include:   The liquid ejecting apparatus according to claim 3, wherein the power supply voltage generation circuit is a DC voltage power supply circuit, or the voltage adjustment circuit is a DC voltage adjustment circuit.   The liquid ejecting apparatus according to claim 3, wherein the power supply voltage generation circuit is an AC voltage power supply circuit, or the voltage adjustment circuit is an AC voltage adjustment circuit.   3. The power supply voltage adjustment circuit is constituted by a power supply circuit capable of boosting a power supply voltage by a bootstrap circuit, and controls boosting of the power supply voltage by the bootstrap circuit by the reference signal. The liquid ejecting apparatus according to 1.   The liquid ejecting apparatus according to claim 6, wherein a diode for preventing backflow is disposed on an output side of the bootstrap circuit.

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