JPWO2017212865A1 - Inkjet head drive waveform signal output apparatus, inkjet recording apparatus, and inkjet head drive waveform signal output method - Google Patents

Abstract

Provided are an inkjet head drive waveform signal output device, an inkjet recording device, and an inkjet head drive waveform signal output method capable of outputting a drive voltage capable of appropriately discharging ink without increasing the size of a power supply unit. To do. The drive waveform signal output device generates and outputs a drive signal having a predetermined drive waveform based on the storage unit storing the emphasized waveform pattern (432a) related to the predetermined drive waveform and the emphasized waveform pattern (432a). A signal generation unit, and a drive waveform amplification circuit (21) that amplifies the power of the generated drive signal having a predetermined drive waveform and outputs the amplified signal to the piezoelectric element (31) of the inkjet head as an output signal. The waveform is an emphasizing waveform that emphasizes a component corresponding to the distortion of the waveform generated in the output signal due to the capacitive component of the piezoelectric element (31) among the initial waveform set as the voltage waveform applied to the piezoelectric element (31).

Description

  The present invention relates to an inkjet head drive waveform signal output apparatus, an inkjet recording apparatus, and an inkjet head drive waveform signal output method.

  Conventionally, there is an ink jet recording apparatus that records an image by discharging ink from a nozzle. In an ink jet recording apparatus, a pressure change is generated in ink in a pressure chamber communicating with the nozzle, whereby ink is ejected from the nozzle as droplets having an appropriate shape and liquid amount. One of the elements used to cause a pressure change in a pressure chamber in an ink jet recording apparatus is a piezoelectric element, and an appropriate voltage is applied to the piezoelectric element to control a deformation amount and a deformation time.

  However, the piezoelectric element is a capacitive load, and switches whether or not ink is ejected from a large number of arranged nozzles, and applies a voltage to the piezoelectric element corresponding to each nozzle that ejects ink according to the switching. Then, the total amount of electric charge that flows from the drive circuit to the piezoelectric element and flows out of the piezoelectric element changes according to the number of piezoelectric elements to which a voltage is applied. Therefore, in order to supply the drive waveform stably, there is a problem that sufficient power supply is required and power consumption increases.

  On the other hand, there is a conventional technique for stabilizing the signal by feeding back the output signal. Patent Document 1 discloses that an output signal obtained by filtering a drive waveform signal obtained by class D amplification by an LC circuit is fed back by advancing the phase, and a differential signal is fed back independently, thereby filtering the LC circuit while suppressing power loss. A technique for maintaining a stable frequency and outputting an appropriate waveform is disclosed.

JP 2009-153272 A

  However, as the number of nozzles in the ink jet recording apparatus increases, the magnitude of the current supplied to the piezoelectric element changes by several orders of magnitude. If a power supply unit capable of supplying sufficient power in accordance with such maximum current is prepared, there is a problem that the power supply unit becomes larger than necessary. On the other hand, when a drive waveform is applied at a high speed without increasing the size of the power supply unit, there is a problem that the drive waveform signal output by a large current becomes dull and ink may not be ejected appropriately.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet head drive waveform signal output device, an inkjet recording device, and an inkjet head drive waveform signal output capable of outputting a drive voltage capable of appropriately discharging ink without increasing the size of the power supply unit. It is to provide a method.

In order to achieve the above object, the invention according to claim 1
A storage unit for storing information relating to a predetermined drive waveform;
A drive signal generation unit that generates and outputs a drive signal of the predetermined drive waveform based on the information stored in the storage unit;
A drive waveform amplification circuit that amplifies the power of the generated drive signal of the predetermined drive waveform and outputs it to the capacitive load of the inkjet head as an output signal;
With
The predetermined drive waveform is an emphasized waveform in which an initial waveform set as a voltage waveform applied to the capacitive load emphasizes a distortion component of a waveform generated in the output signal due to a capacitive component of the capacitive load. This is a drive waveform signal output device for an inkjet head.

According to a second aspect of the present invention, in the drive waveform signal output device for an inkjet head according to the first aspect,
The drive signal generation unit includes a digital-analog conversion unit that converts digital waveform data into an analog signal,
The information related to the predetermined drive waveform is digital waveform data of the emphasized waveform, and the digital waveform data is converted into an analog signal by the digital-analog converter, thereby generating a drive signal of the predetermined drive waveform. It is characterized by that.

According to a third aspect of the present invention, in the drive waveform signal output device for an ink jet head according to the first or second aspect,
The initial waveform is a trapezoidal wave.

According to a fourth aspect of the present invention, in the drive waveform signal output device for an ink jet head according to the third aspect,
The predetermined driving waveform is characterized in that a high frequency component equal to or higher than a predetermined lower limit frequency of the trapezoidal wave is emphasized.

According to a fifth aspect of the present invention, in the drive waveform signal output device for an inkjet head according to the fourth aspect,
The predetermined lower limit frequency is a frequency whose half cycle is shorter than the rise time and fall time of the trapezoidal wave.

A sixth aspect of the present invention is the inkjet head drive waveform signal output device according to any one of the third to fifth aspects,
The predetermined drive waveform is obtained by shortening the rise time and the fall time with respect to the trapezoidal wave, overshooting the voltage at the rise time, and undershooting the voltage at the fall time. It is said.

The invention described in claim 7
An inkjet head having a nozzle and a capacitive load that ejects ink from the nozzle by being deformed according to an applied voltage;
A drive waveform signal output device for an inkjet head according to any one of claims 1 to 6,
An ink jet recording apparatus comprising:

The invention described in claim 8
A storage step for storing information relating to a predetermined drive waveform;
A drive signal generation step of generating and outputting a drive signal of the predetermined drive waveform based on the information stored in the storage step;
A drive waveform amplification step of amplifying the power of the generated drive signal of the predetermined drive waveform and outputting it as an output signal to the capacitive load of the inkjet head;
Including
The predetermined drive waveform is an emphasized waveform in which an initial waveform set as a voltage waveform applied to the capacitive load emphasizes a distortion component of the waveform generated in the output signal according to the capacitance of the capacitive load. This is a drive waveform signal output method for an inkjet head.

  According to the present invention, in the drive waveform signal output device for an inkjet head, there is an effect that it is possible to output a drive voltage capable of appropriately ejecting ink without increasing the size of the power supply unit.

1 is a block diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment of the present invention. It is a figure which shows the example of the waveform pattern of the drive signal input into a drive waveform amplifier circuit, and the drive output signal output. It is a figure which shows the example of the waveform pattern of the drive signal input into a drive waveform amplifier circuit, and the drive output signal output. It is a figure which shows the circuit structure of a drive waveform amplifier circuit. It is a figure which shows the modification of a drive waveform amplifier circuit. It is a figure which shows the modification of a drive waveform amplifier circuit. It is a figure which shows the modification of a drive waveform amplifier circuit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a functional configuration of an ink jet recording apparatus 1 including a drive waveform amplifier circuit of the present invention.

  The inkjet recording apparatus 1 includes a control unit 41, a movement control unit 42, a movement operation unit 51, a communication unit 52, an operation display unit 53, a notification output unit 54, a head drive control unit 20, and an inkjet head 30. These are connected via a bus 55 so that signals can be transmitted and received.

  The control unit 41 controls the overall operation of the inkjet recording apparatus 1. The control unit 41 includes a CPU 411 (Central Processing Unit), a RAM 412 (Random Access Memory), a storage unit 413, and the like.

  The CPU 411 performs various arithmetic processes. The CPU 411 reads out a control program stored in the storage unit 413 and performs various control processes related to image recording and setting thereof.

The RAM 412 provides a working memory space to the CPU 411 and stores temporary data.
The storage unit 413 includes a non-volatile memory that stores a control program, setting data, and the like. Further, the storage unit 413 may include a DRAM or the like that temporarily stores settings related to a droplet discharge command (print job) acquired from the outside via the communication unit 52, image data to be recorded, and the like.

The movement operation unit 51 moves a recording medium, which is a target for recording an image, in a predetermined direction to move the recording medium relative to the inkjet head 30, and performs at least operations related to supply and discharge of the recording medium. Examples of the moving operation unit 51 include an outer periphery of a cylindrical drum carrying a recording medium on the surface and a rotary motor that rotates around the surface of an endless belt. The moving operation unit 51 may be configured to move the recording medium and the inkjet head 30 relative to each other, that is, to move the inkjet head 30 relative to the stationary or moving recording medium.
The movement control unit 42 operates the movement operation unit 51 to perform a control operation for moving the carried recording medium at an appropriate timing and speed. The movement control unit 42 may have a common configuration with the control unit 41.

  The inkjet head 30 is provided with a plurality of nozzles arranged in a predetermined pattern, and records an image on a recording medium by ejecting ink droplets from the openings of the plurality of nozzles at an appropriate timing. The arrangement pattern of the nozzles is not particularly limited, and may be a one-dimensional array or a two-dimensional array. The inkjet head 30 includes a piezoelectric element 31 that is a capacitive load, an ejection selection switching element 32, and the like.

  The piezoelectric element 31 is provided for each of a plurality of nozzles, and is an actuator that discharges liquid droplets from the nozzles by changing the pressure applied to the liquid to be discharged by being deformed according to an applied voltage (drive voltage signal). It is. The deformation mode of the piezoelectric element is not particularly limited as long as the applied voltage corresponds to the deformation amount of the piezoelectric element and the pressure applied to the ink changes according to the deformation.

  The ejection selection switching element 32 switches whether each piezoelectric element 31 is supplied with a drive voltage signal from the head drive control unit 20. The ejection selection switching element 32 switches the presence / absence of ejection of ink droplets from each nozzle by not supplying a drive voltage signal to the piezoelectric element 31 corresponding to the nozzle that does not eject droplets based on image data to be output. . This switching is not limited to the ejection of ink droplets, but is similarly applied to drive voltage signals related to non-ejection waveforms with a small amplitude to the extent that ink droplets are not ejected.

  The head drive control unit 20 outputs a drive voltage signal for driving the piezoelectric element 31 of the inkjet head 30 at an appropriate timing according to each pixel data of the output target image. The head drive control unit 20 may be formed collectively on a substrate or the like, or may be arranged dispersedly in each part of the inkjet recording apparatus 1. A part or all of the configuration of the head drive control unit 20 may be provided in the inkjet head 30. The head drive control unit 20 includes a head control unit 43, a drive waveform amplification circuit 21, a DAC 22 (digital / analog conversion unit), and the like.

  The DAC 22 converts the waveform pattern data (digital waveform data) of the drive waveform output from the head controller 43 at a predetermined clock frequency into an analog signal, and outputs the obtained analog signal (drive signal) to the drive waveform amplifier circuit 21. To do.

  The drive waveform amplification circuit 21 receives a drive signal having a predetermined waveform pattern from the DAC 22 according to the timing of ink droplet ejection from the nozzles, the non-ejection state type, and the like for each piezoelectric element 31. The drive voltage signal amplified by performing the signal amplification operation is output as an output signal. In the ink jet recording apparatus 1 of the present embodiment, a trapezoidal driving voltage signal is applied to the piezoelectric element 31, although not limited thereto.

The head control unit 43 controls the operation of the head drive control unit 20 in accordance with the presence / absence of image data to be recorded and the content of the image data. The head control unit 43 includes a CPU 431, a storage unit 432, and the like. The storage unit 432 emphasizes a waveform pattern 432a (information) corresponding to a waveform pattern (predetermined drive waveform) of a drive signal for ejecting ink from the nozzle or vibrating the liquid level (meniscus) of the ink in the nozzle. Are previously stored as digital discrete value array data. The CPU 431 applies a driving voltage having an appropriate waveform pattern to the piezoelectric element 31 according to whether or not droplets are ejected from each nozzle based on image data to be recorded stored in the storage unit 432 or the storage unit 413. The enhanced waveform pattern data corresponding to the waveform pattern is selected and output to the DAC 22 at an appropriate timing according to a clock signal (synchronization signal) not shown.
The head control unit 43 may be provided in common with the control unit 41.
The movement control unit 42 and the head control unit 43 constitute an operation control unit 40 related to image recording. The head control unit 43 and the DAC 22 constitute a drive signal generation unit, and the drive signal generation unit and the drive waveform amplification circuit 21 constitute a drive waveform signal output device 20a.

  The communication unit 52 communicates with an external device according to a predetermined communication standard, and transmits and receives data. As communication standards to be used, various standards such as TCP / IP by LAN (Local Area Network), short-range wireless communication such as wireless LAN, Bluetooth communication (registered trademark: Bluetooth), USB (Universal Serial Bus), etc. It is possible to use direct communication with an external device. The communication unit 52 receives a print job which is a command related to image recording from an external device, and outputs status information of the inkjet recording apparatus 1 to the external device as necessary.

  The operation display unit 53 accepts user operations and displays information and menus for the user. As the operation display unit 53, for example, a display unit provided with an LCD (liquid crystal display) as the display unit 532 is used, and various menus and statuses related to image recording are displayed on the display screen of the LCD. In addition, a touch panel serving as the operation detection unit 531 is provided corresponding to the LCD, and the touch operation corresponding to the display on the display screen can be detected by arranging the touch panel so as to overlap the display screen of the LCD. Alternatively, the operation display unit 53 may include a push button switch and detect a push operation of the push button switch.

  The notification output unit 54 performs a predetermined notification operation when an abnormality occurs in the inkjet recording apparatus 1. Examples of the notification output unit 54 include a sound generation unit that generates a predetermined beep sound using a piezoelectric element or the like, and a light emitting unit that blinks or lights an LED lamp.

Next, the drive waveform amplification circuit 21 of the ink jet recording apparatus 1 of the present embodiment will be described.
In the inkjet recording apparatus 1 of the present embodiment, as described above, pattern data (digital waveform data) corresponding to an appropriate waveform pattern is predetermined from the emphasized waveform pattern 432a stored and held in the storage unit 432 as digital discrete value array data. Is output from the head control unit 43 in accordance with the clock frequency of the signal, and after analog conversion (D / A conversion) by the DAC 22, power (voltage, then current) is amplified by the drive waveform amplification circuit 21 and output to each piezoelectric element 31. To do.

  2A and 2B are diagrams for explaining the correspondence between the analog signal Vin input from the DAC 22 to the drive waveform amplification circuit 21 and the waveform pattern of the drive output signal Vout output from the drive waveform amplification circuit 21. FIG. The analog signal Vin and the drive output signal Vout have different amplitudes at a ratio corresponding to the amplification factor of the voltage, but are shown here with the same amplitude for explanation.

  In the ink jet recording apparatus 1 according to the present embodiment, a drive voltage signal having a drive waveform pattern having different amplitudes depending on the presence / absence of ink discharge or the discharge amount is output alone or in combination within a predetermined period, and the piezoelectric element 31 is output. By performing the deformation operation, the pressure change with respect to the ink in the nozzle is selectively switched. At this time, if a signal having the same drive waveform pattern as the drive voltage signal of the waveform pattern (initial waveform) originally desired to be applied to the piezoelectric element 31 is to be amplified and output, such as the voltage Vain indicated by the dotted line in FIG. 2A. Actually, the voltage applied to the piezoelectric element 31 is distorted due to the capacitance of the piezoelectric element 31 and the like, as shown by the solid line Vaout in FIG. 2A, and is delayed from the input signal. The rise and fall will be dull.

  On the other hand, the drive waveform amplification circuit 21 takes into account the actual distortion, that is, the voltage Vbin shown by the dotted line in FIG. Also, a drive signal of a waveform with a sudden change, that is, a waveform pattern (a emphasized waveform pattern) with a voltage change that emphasizes a delay amount and a high frequency component is input. Since the frequency related to the rise and fall dullness has a period (particularly a half cycle) shorter than the time required for the rise and fall, it is necessary for the rise and fall in the initial waveform that is a trapezoidal wave here. The emphasized waveform pattern can be generated by emphasizing the higher frequency side with the frequency having a half cycle shorter than time as the lower limit frequency. Alternatively, the power spectrum may be adjusted more finely, or instead of preparing an emphasized waveform pattern analytically or numerically, an appropriate waveform may be obtained experimentally, or the voltage Vbin of FIG. As described above, the rise time and fall time may be shortened from the initial waveform, and a waveform in which an overshoot after the rise and an undershoot after the fall are generated may be roughly drawn. Discrete value data of the emphasized waveform pattern 432a is stored in advance in the storage unit 432 (storage step), and an appropriate emphasized waveform pattern 432a is read out during the ink ejection operation by the inkjet head 30, and the analog signal Vin ( Drive signal) and output (drive signal generation step), which is amplified and output by the drive waveform amplification circuit 21 (drive waveform amplification step), so that the finally emphasized component is actually generated. A drive voltage signal with a voltage change close to the original drive waveform pattern is applied to the piezoelectric element 31 as shown by the solid line in FIG.

  FIG. 3 is a diagram illustrating a configuration relating to amplification of a drive waveform in the inkjet recording apparatus 1 of the present embodiment.

  The drive waveform amplifier circuit 21 includes a voltage amplifier 211, a current amplifier 214, and the like.

  The voltage amplifying unit 211 amplifies the voltage of the analog signal Vin having the driving waveform input from the DAC 22 to the driving voltage. Since the voltage amplitude of the analog signal Vin output from the DAC 22 is smaller than the actual voltage for driving the piezoelectric element 31, the voltage amplifier 211 amplifies and outputs the amplified voltage.

  The voltage amplification unit 211 includes an OP amplifier A1 (operational amplifier), resistance elements R11 and R13, and the like. The OP amplifier A1 is connected to voltages + Vc1 and −Vc2 corresponding to the amplitude of the drive voltage, and voltage amplification is performed between the voltages + Vc1 and −Vc2 with an amplification factor according to the resistance ratio of the resistance elements R11 and R13. . The drive signal subjected to the voltage amplification is sent to the current amplification unit 214 via the resistance element R12. In the inkjet head 30, the amplitude of the drive voltage is usually as large as several tens of volts (about 30 V to 45 V), and the OP amplifier A1 corresponding to such a high voltage usually has a slew rate and a gain bandwidth (GBW). ) Becomes low, the waveform of the output drive signal tends to become dull. In the ink jet recording apparatus 1, it is preferable that the voltage amplitude of the analog signal Vin output from the DAC 22 is set to be larger than that in the past (for example, an amplitude of about 3 V) so that the amplification factor is not excessively increased. Here, + Vc1> 0 and −Vc2 <0.

  The current amplifying unit 214 amplifies the power of the driving signal output from the voltage amplifying unit 211, and outputs it as a driving output signal Vout to the piezoelectric element 31 selected by the ejection selection switching element 32 via the resistance element R51. Apply voltage. The current amplifying unit 214 includes resistance elements R40 to R46, an N channel FET 41T (field effect transistor), a P channel FET 42T, a capacitor C41, and the like.

The N-channel FET 41T and the P-channel FET 42T are source followers that output a drive output signal according to the drive signal by a push-pull operation.
The drive signal input to the current amplifier 214 via the resistance element R40 is divided and input to the gate of the N-channel FET 41T and the gate of the P-channel FET 42T, respectively. The input voltage to the gate of the N-channel FET 41T is added with a bias voltage obtained by dividing the potential difference between the power supply voltage Vp and the input voltage by the resistance ratio of the resistance elements R41 and R45, and the input voltage to the gate of the P-channel FET 42T is A bias voltage obtained by dividing the potential difference between the ground voltage and the input voltage by the resistance ratio of the resistance elements R42 and R46 is drawn. Thereby, crossover distortion is avoided. The N-channel FET 41T has a drain connected to the power supply voltage Vp, and a source connected to the output terminal via the resistor element R43. The drain of the P-channel FET 42T is grounded, and the source is connected to the output terminal via the resistor element R44.

The N-channel FET 41T and the P-channel FET 42T are MOSFETs that amplify power (current) and output a voltage signal according to the voltage signal input to each gate terminal. By using a MOSFET instead of a bipolar transistor, the power amplifying unit 214 suppresses the occurrence of thermal runaway due to positive feedback of changes in bias voltage and amplified current accompanying heat generation (temperature rise).
The capacitor C41 is for stabilizing the power supply voltage Vp, and a capacitor having a larger capacity than other capacitors such as an electrolytic capacitor is preferably used. The power supply voltage Vp is equal to or higher than the operating voltage + Vc1 supplied to the OP amplifiers A1 and A2, and is the same here.

  As described above, when the analog signal Vin based on the emphasized waveform pattern is input from the DAC 22 to the drive waveform amplifier circuit 21, the power is amplified and output as the drive output signal Vout. The drive output signal Vout is delayed and dull due to the capacitance of the piezoelectric element 31, and the forward and high frequency emphasized portions are canceled out. As a result, the drive voltage corresponding to the waveform pattern to be originally applied to the piezoelectric element 31 is obtained. Is applied to the piezoelectric element 31.

  The emphasized waveform pattern 432a may be inspected and set before shipment for each inkjet recording apparatus 1 and individually stored in the storage unit 43, or each inkjet recording in which common data is manufactured for a specific inkjet recording apparatus model. You may make it memorize | store in the memory | storage part 43 of the apparatus 1, respectively. Also, a plurality of types of data may be stored in the storage unit 43 in advance so that appropriate data can be selected and set for the inkjet recording apparatus 1 at the time of inspection before shipment.

[Modification]
4A to 4D are configuration diagrams showing modifications of the drive waveform signal output device 20a of the present embodiment.
As shown in FIG. 4A, in the drive waveform amplifying circuit 21a, a voltage amplified drive signal is input to a PWM modulation unit 213 (Pulse Width Modulation), and once subjected to pulse width modulation (PWM). The demodulator 215 can return the signal to an analog signal. As the waveform demodulator 215, for example, a low-pass filter (LPF) using an LC circuit is used.

  In addition, as shown in FIG. 4B, in the drive waveform amplification circuit 21b, the drive output signal Vout amplified by the current amplification unit 214 may be negatively fed back to the feedback unit 212. Here, an example in which negative feedback is performed between the voltage amplification unit 211 and the current amplification unit 214 is shown. However, the voltage division unit 211 divides the drive output signal Vout according to the voltage amplification factor in the voltage amplification unit 211. You may make negative feedback before. In this case, in order to prevent oscillation due to negative feedback, processing such as suppression of high-frequency signal feedback may be performed using an LPF or the like. Further, the emphasized waveform pattern 432a stored in the storage unit 432 is a waveform pattern that takes into account the improvement of the output waveform by negative feedback.

  As shown in FIG. 4C, the storage unit 432 may store a normal waveform pattern and an emphasis parameter 432b used for generating the emphasis waveform pattern instead of storing the emphasis waveform pattern. The CPU 431 uses these to perform an enhanced waveform generation process for generating an enhanced waveform pattern, and causes the DAC 22 to output data of the generated enhanced waveform pattern. When it is possible to generate an emphasized waveform pattern only by parameter setting, and when the parameter setting is appropriately changed in accordance with an output image or the like, this is more preferable than storing all the emphasized waveform patterns in the storage unit 432. Such a modification may be more efficient.

As described above, the drive waveform signal output device 20a for the inkjet head according to the present embodiment has a storage unit 432 that stores information related to a predetermined drive waveform, and a predetermined drive based on the information stored in the storage unit 432. The head control unit 43 and the DAC 22 as a drive signal generation unit that generates and outputs a waveform drive signal (analog signal Vin), and amplifies the power of the generated drive signal having a predetermined drive waveform to generate a drive output signal Vout. A drive waveform amplification circuit 21 that outputs to the piezoelectric element 31 of the inkjet head 30, and the predetermined drive waveform is a capacitance component of the piezoelectric element 31 in an initial waveform pattern set as a voltage waveform to be applied to the piezoelectric element 31. This is an emphasized waveform pattern 432a in which a component corresponding to the waveform distortion generated in the drive output signal Vout is emphasized.
As described above, in consideration of the distortion of the waveform due to the influence of the capacitance component of the piezoelectric element 31, the enhanced waveform pattern 432a in which the distortion is emphasized so that an appropriate drive voltage signal is obtained as a result of the distortion is stored. In addition, an analog signal Vin is generated from the emphasized waveform pattern 432a and amplified, whereby a drive voltage having a more appropriate waveform pattern is applied to the piezoelectric element 31. Thereby, ink can be discharged from the nozzle with higher accuracy. That is, the drive waveform signal output device 20a can output a drive voltage that enables appropriate ink ejection.

The drive signal generation unit includes a DAC 22 that converts digital waveform data into an analog signal. Information relating to a predetermined drive waveform is digital waveform data of an emphasized waveform pattern, and the digital waveform data is converted into an analog signal by the DAC 22. A drive signal having a predetermined drive waveform is generated by the conversion.
As described above, the waveform pattern data that has been emphasized and corrected in order to obtain a drive voltage signal having an appropriate waveform pattern is stored in advance, so that the drive signal of this waveform pattern can be easily and reliably transmitted to the drive waveform amplification circuit 21. When input, an appropriate drive voltage signal is finally obtained. Accordingly, appropriate ink ejection can be performed easily and reliably, and the inkjet recording apparatus 1 can perform highly accurate image recording.

  The initial waveform is a trapezoidal wave. By applying the present invention to such a waveform with a clear rise and fall period, an appropriate drive voltage signal can be obtained easily and more effectively, thereby enabling more accurate ink ejection. become.

  In addition, since the predetermined drive waveform emphasizes a high-frequency component of the trapezoidal wave that is equal to or higher than the predetermined lower limit frequency, drive waveform data and drive waveform signal for obtaining a more appropriate drive voltage signal through easy processing Can be determined.

  Further, the predetermined lower limit frequency is a frequency whose half cycle is shorter than the rise time and fall time of the trapezoidal wave, and emphasizes the high frequency component related to the delay and dullness of the rise and fall due to the capacitive component of the piezoelectric element 31. Thus, an appropriate drive voltage signal can be easily obtained.

  The predetermined drive waveform is obtained by shortening the rise time and fall time with respect to the trapezoidal wave, overshooting the voltage at the time of rise, and undershooting the voltage at the time of fall. Specifically, by setting such a waveform in advance, an appropriate trapezoidal driving voltage signal can be applied to the piezoelectric element 31 when it is affected by the capacitance component of the piezoelectric element 31.

Further, the inkjet recording apparatus 1 of the present embodiment includes an inkjet head 30 having a nozzle and a piezoelectric element 31 that ejects ink from the nozzle by being deformed according to an applied voltage, and the above-described drive waveform signal output. And a device 20a.
In the ink jet recording apparatus 1, it becomes possible to reduce the influence of the capacitive component of the piezoelectric element 31 and apply an appropriate drive voltage to the piezoelectric element 31, thereby accurately ejecting ink and recording image quality. Can be improved.

  Further, in the above-described drive waveform signal output method, the distortion is emphasized so that an appropriate drive voltage signal can be obtained as a result of the distortion in consideration of the waveform being distorted in advance due to the capacitive component of the piezoelectric element 31. By storing the emphasized waveform pattern 432a, generating an analog signal Vin from the emphasized waveform pattern 432a, and amplifying the analog signal Vin, a drive voltage having a more appropriate waveform pattern can be applied to the piezoelectric element 31. . Accordingly, it is possible to improve the accuracy of the recorded image by discharging the ink from the nozzle with higher accuracy. That is, according to this drive waveform signal output method, it is possible to output a drive voltage that allows appropriate ink ejection.

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, in the above-described embodiment, the current output is amplified by the push-pull configuration using the MOSFET and the drive output signal Vout is output. However, the current may be amplified by combining bipolar transistors. Further, the number of transistors is not limited to two. Three or more transistors may be used, for example, Darlington connection or the like.

  In the above embodiment, the voltage amplification unit 211 performs voltage amplification by the OP amplifier A1. However, voltage amplification may be performed using a bipolar transistor or the like, or a combination of these may be used in multiple stages. Voltage amplification may be performed.

  Further, the drive waveform signal output device 20a shown in the above embodiment may be manufactured, traded, used, etc. independently of the ink jet recording apparatus 1.

In the above embodiment, the trapezoidal wave is described as the initial waveform, but the present invention is not limited to this. It may be a rectangular wave or other waveform.
In addition, the specific details shown in the above embodiment can be appropriately changed without departing from the gist of the present invention.

  The present invention can be used in an inkjet head drive waveform signal output apparatus, an inkjet recording apparatus, and an inkjet head drive waveform signal output method.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 20 Head drive control part 20a Drive waveform signal output device 21, 21a, 21b Drive waveform amplification circuit 211 Voltage amplification part 212 Feedback part 213 PWM modulation part 214 Current amplification part 215 Waveform demodulation part 30 Inkjet head 31 Piezoelectric element 32 Discharge selection switching element 40 Operation control unit 41 Control unit 411 CPU
412 RAM
413 Storage unit 42 Movement control unit 43 Head control unit 431 CPU
432 Storage unit 51 Moving operation unit 52 Communication unit 53 Operation display unit 531 Operation detection unit 532 Display unit 54 Notification output unit 55 Bus A1, A2 OP amplifier C21, C31, C41 Capacitor 41T N channel FET
42T P-channel FET
R11, R12, R21, R31, R41-R44, R51 resistance element

Claims (8)

A storage unit for storing information relating to a predetermined drive waveform;
A drive signal generation unit that generates and outputs a drive signal of the predetermined drive waveform based on the information stored in the storage unit;
A drive waveform amplification circuit that amplifies the power of the generated drive signal of the predetermined drive waveform and outputs it to the capacitive load of the inkjet head as an output signal;
With
The predetermined drive waveform is an enhanced waveform in which a component corresponding to a waveform distortion generated in the output signal due to a capacitive component of the capacitive load is emphasized among initial waveforms set as a voltage waveform applied to the capacitive load. A drive waveform signal output device for an ink jet head, characterized in that The drive signal generation unit includes a digital-analog conversion unit that converts digital waveform data into an analog signal,
The information related to the predetermined drive waveform is digital waveform data of the emphasized waveform, and the digital waveform data is converted into an analog signal by the digital-analog converter, thereby generating a drive signal of the predetermined drive waveform. The drive waveform signal output device for an inkjet head according to claim 1.   3. The drive waveform signal output device for an ink jet head according to claim 1, wherein the initial waveform is a trapezoidal wave.   4. The drive waveform signal output device for an ink jet head according to claim 3, wherein the predetermined drive waveform emphasizes a high frequency component having a frequency equal to or higher than a predetermined lower limit frequency in the trapezoidal wave.   5. The drive waveform signal output device for an ink jet head according to claim 4, wherein the predetermined lower limit frequency is a frequency whose half cycle is shorter than the rise time and fall time of the trapezoidal wave.   The predetermined drive waveform is obtained by shortening the rise time and the fall time with respect to the trapezoidal wave, overshooting the voltage at the rise time, and undershooting the voltage at the fall time. The drive waveform signal output device for an inkjet head according to any one of claims 3 to 5. An inkjet head having a nozzle and a capacitive load that ejects ink from the nozzle by being deformed according to an applied voltage;
A drive waveform signal output device for an inkjet head according to any one of claims 1 to 6,
An ink jet recording apparatus comprising: A storage step for storing information relating to a predetermined drive waveform;
A drive signal generation step of generating and outputting a drive signal of the predetermined drive waveform based on the information stored in the storage step;
A drive waveform amplification step of amplifying the power of the generated drive signal of the predetermined drive waveform and outputting it as an output signal to the capacitive load of the inkjet head;
Including
The predetermined drive waveform is an emphasized waveform in which an initial waveform set as a voltage waveform applied to the capacitive load emphasizes a distortion component of the waveform generated in the output signal according to the capacitance of the capacitive load. A method of outputting a drive waveform signal of an inkjet head.

Images