JP2005125804A - Liquid ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejector capable of driving a liquid ejection head at higher frequencies. <P>SOLUTION: The liquid ejector is arranged such that a driving signal generating circuit generates first driving signal COM1 and second driving signal COM2 separately. The first driving signal COM1 consists of two middle dot driving pulses DP1 and DP2 being used when a large dot is recorded. Other driving pulse, i.e. a composite pulse connecting a small dot driving pulse DP3 and an anterior fine oscillation waveform PS4 through a connection waveform element PS5 is included in the second driving signal. In the liquid ejector, first and second switches are controlled by a decoder, a control logic and each level shifter, waveform parts PS1-PS7 composing the first driving signal COM1 and the second driving signal COM2 are fed, in combination, to a piezoelectric vibrator. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid ejecting apparatus equipped with a liquid ejecting head capable of ejecting various liquids as droplets, such as an ink jet recording apparatus, a display manufacturing apparatus, an electrode forming apparatus, or a biochip manufacturing apparatus, and in particular, a landing floor. The present invention relates to an apparatus capable of controlling the discharge of liquid droplets from a nozzle opening by controlling the supply of a drive pulse to a pressure generating element according to the tone.

  The liquid ejecting apparatus is an apparatus that ejects liquid in a droplet state from a nozzle opening. For example, an image recording apparatus that ejects ink droplets to record an image or the like on a recording paper, and ejects a liquid electrode material onto a substrate. An electrode forming apparatus for forming an electrode, a biochip manufacturing apparatus for manufacturing a biochip by discharging a biological sample, or a micropipette for discharging a predetermined amount of a sample to a container has been proposed.

  In this liquid ejecting apparatus, the amount of droplets ejected from the nozzle opening can be changed in order to achieve both high-speed processing for the landing target on which the droplets land and high accuracy in controlling the amount of landing. Has been proposed. For example, in an ink jet recording apparatus which is a kind of the liquid ejecting apparatus, a single driving signal is generated in which a plurality of driving pulses are included in a series within one recording period, and the recording data (gradation data) is used. Thus, by supplying a necessary portion of the drive signal to the pressure generating element, the amount of ink ejected from the nozzle opening is changed (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-81012 (page 9, FIG. 9)

  By the way, in the conventional configuration in which a necessary part of a single drive signal is supplied to the pressure generating element, there is a problem that it is difficult to sufficiently exhibit the original performance of the liquid ejecting head. That is, due to the relationship in which a plurality of drive pulses are included in one ejection cycle, the liquid ejecting head (pressure generating element) has to be driven at a frequency lower than the maximum driveable frequency.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting apparatus that can drive a liquid ejecting head at a higher frequency.

The present invention has been proposed to achieve the above object, and includes a pressure generating element capable of causing pressure fluctuation in the liquid in the pressure chamber, and a liquid ejecting head having a nozzle opening communicating with the pressure chamber;
Drive signal generating means for repeatedly generating a drive signal including a drive pulse every discharge cycle,
In a liquid ejecting apparatus capable of controlling the supply of a driving pulse to a pressure generating element according to the landing gradation and controlling the discharge of a droplet from a nozzle opening,
The drive signal generating means has only a first drive pulse used at a landing gradation having the largest amount of landing liquid per unit area, and generates the first drive pulse at equal intervals; A series of second drive signals having a second drive pulse used in other landing gradations, and the generation period of the first drive pulse and the generation period of the second drive pulse are overlapped at least partially; It is characterized by that.

  According to the present invention, since the generation period of the first drive pulse and the generation period of the second drive pulse are overlapped at least partially, the generation interval of the first drive pulse is free without being restricted by the second drive pulse. Can be set. Therefore, the generation interval of the first drive pulse can be set according to the response frequency of the pressure generating element. As a result, the liquid ejecting head can be driven at a higher frequency.

In this configuration, it is preferable to generate the second drive pulse in the middle between the adjacent first drive pulses.
According to this configuration, it is possible to prevent a bias related to the droplet discharge interval.

In addition, the second driving pulse causes a small droplet driving pulse having a smaller discharge liquid volume than the first driving pulse, or causes the meniscus to vibrate slightly by applying a pressure fluctuation to the liquid in the pressure chamber to such an extent that the droplet is not discharged. A fine vibration pulse is preferable. The “landing gradation” described above is information indicating the amount of liquid landing per unit area, and is a superordinate concept of “recording gradation” in the recording apparatus.
The “meniscus” is the free surface of the liquid exposed at the nozzle opening.

In the above configuration, the second driving pulse may be a composite pulse in which a small droplet driving pulse and a fine vibration waveform are connected by a connection waveform element.
According to the present invention, it is possible to efficiently include a plurality of types of drive pulses in a limited ejection cycle.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, an ink jet printer is taken as an example. In this printer, liquid ink (a kind of liquid according to the present invention) is ejected from a recording head (a kind of liquid ejecting head according to the present invention) in the form of droplets, which is a kind of liquid ejecting apparatus according to the present invention. It is.

  The printer illustrated in FIG. 1 includes a printer controller 1 and a print engine 2. The printer controller 1 includes an interface 3 (hereinafter referred to as an external I / F 3) that receives print data (a type of first control data sent from a host device) and the like from a host computer (not shown), and various data. Are supplied to the RAM 4, the ROM 5 that stores various data processing routines, the control unit 6 including a CPU, the oscillation circuit 7 that generates the clock signal (CK), and the recording head 8. A drive signal generation circuit 9 that generates drive signals (COM1, COM2) and an interface 10 (hereinafter referred to as an internal I / F 10) for transmitting recording data, drive signals, and the like to the print engine 2 are provided. .

  The external I / F 3 receives print data including, for example, any one or more of character code, graphic function, and image data from a host computer or the like. The external I / F 3 outputs a busy signal (BUSY), an acknowledge signal (ACK), and the like to the host computer.

  The RAM 4 is used as a reception buffer, an intermediate buffer, an output buffer, a work memory (not shown), and the like. Print data from the host computer received by the external I / F 3 is temporarily stored in the reception buffer. The intermediate buffer stores intermediate code data converted into an intermediate code by the control unit 6. In the output buffer, recording data sent to the recording head 8 (a type of second control data sent to the liquid jet head) is developed. The ROM 5 stores various control routines executed by the control unit 6, font data and graphic functions, various procedures, and the like.

The drive signal generation circuit 9 corresponds to the drive signal generation means of the present invention, and includes a first drive signal generation section 9A (first drive signal generation means) capable of generating the first drive signal COM1, and a second drive signal COM2. And a second drive signal generating section 9B (second drive signal generating means) that can be generated. As shown in FIG. 3, the first drive signal COM1 is a series of signals having two middle dot drive pulses DP1 and DP2 within one recording period T, and is repeatedly generated every recording period T. Here, the middle dot drive pulses DP1 and DP2 are drive pulses for ejecting an amount of ink droplets (a kind of medium droplet) corresponding to the middle dots, and correspond to a kind of the first drive pulse of the present invention. . The second drive signal COM2 includes a composite pulse (a kind of the second drive pulse of the present invention) in which the small dot drive pulse DP3 and the front side fine vibration waveform (PS4) are connected by the connection waveform element (PS5) for one recording period. A series of signals having one in T, which is repeatedly generated every recording period T.
The recording cycle T is a repeating unit of the drive signal COM and is a kind of ejection cycle in the present invention. The drive signals COM1 and COM2 will be described in detail later.

  The control unit 6 controls signal generation for the drive signal generation circuit 9 or develops print data from the host computer into print data for transmission to the print head 8. Then, at the time of development into recording data, the control unit 6 first reads the print data in the reception buffer, converts it into an intermediate code, and stores this intermediate code data in the intermediate buffer. Next, the control unit 6 analyzes the intermediate code data read from the intermediate buffer, and expands the intermediate code data into recording data for each dot by referring to the font data and graphic functions in the ROM 5.

The recording data of this embodiment is composed of gradation data in which one dot is 2 bits. The gradation data includes, for example, gradation data [00] indicating non-recording (fine vibration in printing), gradation data [01] indicating recording by small dot, and gradation data [01] indicating recording by middle dots [ 10] and gradation data [11] indicating recording by large dots.
Therefore, with this configuration, each dot can be recorded with four gradations. Regarding these four types of recording gradations, the amount of landing ink per unit area is the largest for large dots and the second for middle dots. Further, the recording gradation of the small dot is the third largest, and the non-recording recording gradation is 0 (pL).
The recording gradation described above corresponds to a subordinate concept of the landing gradation of the present invention, and is information indicating the amount of ink landing per unit area.

  The control unit 6 constitutes a part of the timing signal generating means, and supplies a latch signal (LAT) and channel signals (CH-A, CH-B) to the recording head 8 through the internal I / F 10. The latch pulses and channel pulses included in these latch signals and channel signals define the supply start timings of a plurality of waveform sections and adjustment elements (PS1 to PS7, P0, P20) constituting the drive signals COM1 and COM2.

Specifically, as shown in FIG. 3, the latch pulse LAT1 defines the supply start timing of the adjustment elements P0 and P20 generated in the vibrator charging period (period t10, period t20).
The first channel pulse CH11 in the first channel signal CH-A defines the supply start timing of the first waveform part PS1 generated in the period t11 of the first drive signal COM1, and the second channel pulse CH12 is in the period. The supply start timing of the second waveform portion PS2 generated at t12 is defined.
Similarly, the first channel pulse CH21 in the second channel signal CH-B defines the supply start timing of the third waveform portion PS3 generated in the period t21 of the second drive signal COM2, and the second channel pulse CH22 is in the period t22. The third waveform pulse CH23 defines the supply start timing of the fifth waveform part PS5 generated in the period t23. The fourth channel pulse CH24 defines the supply start timing of the sixth waveform section PS6 generated in the period t24, and the fifth channel pulse CH25 defines the supply start timing of the seventh waveform section PS7 generated in the period t25. To do.

  Next, the print engine 2 will be described. As shown in FIG. 1, the print engine 2 includes a recording head 8, a carriage mechanism 11, and a paper feed mechanism 12.

  The carriage mechanism 11 includes a carriage to which the recording head 8 is attached, a drive motor (for example, a DC motor) that drives the carriage via a timing belt and the like, and moves the recording head 8 in the main scanning direction. The paper feed mechanism 12 includes a paper feed motor, a paper feed roller, and the like, and sequentially feeds recording paper (a type of print recording medium) to perform sub-scanning.

  The recording head 8 is a kind of liquid jet head according to the present invention. Hereinafter, the recording head 8 will be described in detail. First, the structure of the recording head 8 will be described with reference to FIG. The illustrated recording head 8 includes a vibrator unit 24 in which a plurality of piezoelectric vibrators 21, a fixing plate 22, a flexible cable 23 and the like are unitized, a case 25 in which the vibrator unit 24 can be stored, And a flow path unit 26 joined to the front end surface.

  The case 25 is a synthetic resin block-like member in which a housing empty portion 27 having an open front end and a rear end is formed, and the vibrator unit 24 is housed and fixed in the housing empty portion 27.

The piezoelectric vibrator 21 is a kind of pressure generating element in the present invention, and is formed in a comb shape in this embodiment. The piezoelectric vibrator 21 is a laminated piezoelectric vibrator configured by alternately laminating piezoelectric bodies and internal electrodes, and is a longitudinal vibration mode piezoelectric vibrator capable of expanding and contracting in a vertical direction perpendicular to the stacking direction. It is. The tip surface of each piezoelectric vibrator 21 is joined to the island portion 28 of the flow path unit 26.
The piezoelectric vibrator 21 behaves like a capacitor. That is, the potential of the piezoelectric vibrator 21 (vibrator potential) is increased by charging, and the potential is decreased by discharging. When the signal supply is stopped, the potential of the piezoelectric vibrator 21 is maintained at the potential immediately before the stop.

  The flow path unit 26 has the nozzle plate 30 disposed on one surface side of the flow path formation substrate 29 with the flow path formation substrate 29 interposed therebetween, and the elastic plate 31 on the other surface opposite to the nozzle plate 30. It is configured by arranging and laminating on the side.

  The nozzle plate 30 is constituted by a thin metal plate material (for example, stainless steel plate) in which a plurality (for example, 96) of nozzle openings 32 are opened along the sub-scanning direction. The flow path forming substrate 29 includes an ink flow path (a type of liquid flow path) including a reservoir 33 (common ink chamber), an ink supply port 34 (a type of liquid supply port), a pressure chamber 35, and a nozzle communication port 36. It is the formed plate-shaped member. In this embodiment, the flow path forming substrate 29 is produced by etching a silicon wafer. The elastic plate 31 is a composite plate material having a double structure in which a resin film 38 is laminated on a stainless support plate 37, and the support plate 37 corresponding to the pressure chamber 35 is removed in an annular shape so that the island portion 28 is removed. Forming.

  In the recording head 8, a series of ink flow paths from the reservoir 33 through the pressure chamber 35 to the nozzle opening 32 is formed for each nozzle opening 32. Then, the piezoelectric vibrator 21 is deformed by charging or discharging the piezoelectric vibrator 21. That is, the piezoelectric vibrator 21 in the longitudinal vibration mode contracts in the longitudinal direction of the vibrator by charging and extends in the longitudinal direction of the vibrator by discharging. For this reason, when the vibrator potential is increased by charging, the island portion 28 is pulled toward the piezoelectric vibrator side, the resin film 38 around the island portion is deformed, and the pressure chamber 35 is expanded. When the vibrator potential is lowered by the discharge, the piezoelectric vibrator 21 extends in the return direction and the pressure chamber 35 contracts.

  Thus, since the volume of the pressure chamber 35 can be controlled according to the vibrator potential, the ink pressure in the pressure chamber 35 can be varied, and ink droplets can be ejected from the nozzle openings 32. For example, ink droplets can be ejected by expanding the reference volume pressure chamber 35 once and then rapidly contracting it.

  Next, the electrical configuration of the recording head 8 will be described.

As shown in FIG. 1, the recording head 8 includes a shift register circuit including a first shift register 41 and a second shift register 42, a latch circuit including a first latch circuit 43 and a second latch circuit 44, and a decoder. 45, a control logic 46, a level shifter circuit including a first level shifter 47 and a second level shifter 48, a switch circuit including a first switch 49 and a second switch 50, and the piezoelectric vibrator 21.
Each shift register 41, 42, each latch circuit 43, 44, each level shifter 47, 48, each switch 49, 50, and each piezoelectric vibrator 21 are provided in correspondence with the nozzle opening 32.

  The recording head 8 ejects ink droplets based on recording data (SI) from the printer controller 1. In this embodiment, since the upper bit group of the recording data and the lower bit group of the recording data are sent to the recording head 8 in this order, first, the upper bit group of the recording data is set in the second shift register 42. When the upper bit group of the recording data is set in the second shift register 42 for all the nozzle openings 32, the lower bit group of the recording data is subsequently set in the second shift register 42. Along with the setting of the lower bit group of the recording data, the upper bit group of the recording data is shifted and set in the first shift register 41.

  A first latch circuit 43 is electrically connected to the first shift register 41, and a second latch circuit 44 is electrically connected to the second shift register 42. When a latch pulse (LAT1) from the printer controller 1 is input to the latch circuits 43 and 44, the first latch circuit 43 latches the upper bit group of the recording data, and the second latch circuit 44 stores the recording data. Latch the lower bit group.

  The recording data (upper bit group and lower bit group) latched by the latch circuits 43 and 44 are input to the decoder 45, respectively. The decoder 45 performs translation based on the upper bit group and the lower bit group of the recording data, and selects the waveform sections PS1 to PS7 and the adjustment elements P0 and P20 constituting the drive signals COM1 and COM2 shown in FIG. Waveform selection data is generated.

  In the present embodiment, the waveform selection data is generated for each drive signal COM1, COM2. That is, as shown in FIG. 3, the first waveform selection data corresponding to the first drive signal COM1 includes the first adjustment element P0 (period t10), the first waveform section PS1 (period t11), and the second waveform section. It consists of a total of 3 bits of data corresponding to PS2 (period t12). The second waveform selection data corresponding to the second drive signal COM2 includes the second adjustment element P20 (period t20), the third waveform section PS3 (period t21), the fourth waveform section PS4 (period t22), and the fifth waveform. It consists of data of a total of 6 bits corresponding to the part PS5 (period t23), the sixth waveform part PS6 (period t24), and the seventh waveform part PS7 (period t25).

  The decoder 45 that operates in this manner functions as waveform selection data generation means, and generates a plurality of sets of waveform selection data corresponding to the drive signals from the recording data (gradation data).

The decoder 45 also receives a timing signal from the control logic 46. The control logic 46 functions as a timing signal generating means together with the control unit 6, and is synchronized with the input of the latch signal (LAT) and the channel signals (CH-A, CH-B) and the timing signal (TYM-A, TYM-B) is generated.
This timing signal is also generated for each of the drive signals COM1 and COM2. That is, as shown in FIG. 3, the control logic 46 generates the first timing signal (TYM-A) from the latch pulse (LAT1) and the channel pulses (CH11, CH12) for the first drive signal COM1. The second timing signal (TYM-B) is generated by the latch pulse and the channel pulses (CH21 to CH25) for the second drive signal COM2.

  Each waveform selection data generated by the decoder 45 is sequentially input to the level shifters 47 and 48 from the upper bit side at the timing specified by the timing signal. That is, the first waveform selection data is input to the first level shifter 47 in accordance with the generation timing of each timing pulse included in the first timing signal TYM-A. In addition, the second waveform selection data is input to the second level shifter 48 in accordance with the generation timing of each timing pulse included in the second timing signal TYM-B.

  These level shifters 47 and 48 function as voltage amplifiers. When the waveform selection data is [1], the electric signals boosted to a voltage capable of driving the corresponding switches 49 and 50, for example, a voltage of about several tens of volts. Is output. That is, when the first waveform selection data is [1], an electrical signal is output to the first switch 49, and when the second waveform selection data is [1], an electrical signal is output to the second switch 50. .

  The first drive signal COM1 from the drive signal generation circuit 9 is supplied to the input side of the first switch 49, and the second drive signal COM2 is supplied to the input side of the second switch 50. The piezoelectric vibrator 21 is electrically connected to the output side of the switches 49 and 50. The first switch 49 and the second switch 50 are provided for each type of drive signal to be generated, and are interposed between the drive signal generation circuit 9 and the piezoelectric vibrator 21 to drive each drive signal COM1. , COM2 are selectively supplied to the piezoelectric vibrator 21. The first switch 49 and the second switch 50 that operate in this way function as first switch means (a kind of switch means of the present invention).

  The above waveform selection data controls the operation of each switch 49, 50. That is, during the period in which the waveform selection data input to the first switch 49 is [1], the first switch 49 is in a conductive state, and the first drive signal COM1 is supplied to the piezoelectric vibrator 21. Similarly, during the period in which the waveform selection data input to the second switch 50 is [1], the second drive signal COM2 is supplied to the piezoelectric vibrator 21. Then, the vibrator potential of the piezoelectric vibrator 21 changes according to the supplied drive signals COM1 and COM2. On the other hand, while the waveform selection data input to the switches 49 and 50 are both [0], the electric signals for operating the switches 49 and 50 are not output from the level shifters 47 and 48. A drive signal is not supplied to the child 21. In short, the adjustment elements P0 and P20 and the waveform portions (the first waveform portion PS1 to the seventh waveform portion PS7) in the period in which [1] is set as the waveform selection data are selectively supplied to the piezoelectric vibrator 21. .

  As described above, in this embodiment, the decoder 45, the control logic 46, and the level shifters 47 and 48 function as the switch control means of the present invention, and the switches 49 and 50 are set according to the recording data (gradation data). Control.

  Next, the drive signals COM1 and COM2 generated by the drive signal generation circuit 9 and the supply control of these drive signals COM1 and COM2 to the piezoelectric vibrator 21 will be described.

  As described above, the drive signal illustrated in FIG. 3 includes the first drive signal COM1 and the second drive signal COM2. The first drive signal COM1 includes a first adjustment element P0 generated in the period t10, a first waveform section PS1 generated in the period t11, and a second waveform section PS2 generated in the period t12. The second drive signal COM2 includes the second adjustment element P20 generated in the period t20, the third waveform part PS3 generated in the period t21, the fourth waveform part PS4 generated in the period t22, and the period t23. The fifth waveform section PS5 generated in the period t6, the sixth waveform section PS6 generated in the period t24, and the seventh waveform section PS7 generated in the period t25.

  First, the first drive signal COM1 will be described.

The first adjustment element P0 is constituted by a waveform element that is constant at the intermediate potential Vhm. As will be described later, the first adjustment element P0 is supplied to the piezoelectric vibrator 21 in order to adjust the vibrator potential to the intermediate potential Vhm at the beginning of the recording cycle T.
The intermediate potential Vhm is a kind of reference potential and is also the start / end potential of each drive pulse DP1 to DP3.

  The first waveform portion PS1 includes a first constant potential element P1, a first expansion element P2, a first expansion hold element P3, a first discharge element P4, a vibration suppression hold element P5, and an expansion vibration suppression element P6. And a second constant potential element P7. The first constant potential element P1 is a waveform element that is constant at the intermediate potential Vhm, and the first expansion element P2 applies a potential with a relatively gentle constant gradient that does not cause ink droplets to be ejected from the intermediate potential Vhm to the first expansion potential Vh1. The first expansion hold element P3 is a waveform element that is constant at the first expansion potential Vh1. The first discharge element P4 is a waveform element that drops the potential with a steep slope from the first expansion potential Vh1 to the contraction potential VL, and the vibration suppression hold element P5 is a waveform element that is constant at the contraction potential VL. The expansion damping element P6 is a waveform element that increases the potential at a constant gradient that does not cause ink droplets to be ejected from the contraction potential VL to the intermediate potential Vhm, and the second constant potential element P7 is a waveform element that is constant at the intermediate potential Vhm. .

  The second waveform portion PS2 includes a third constant potential element P8, a first expansion element P9, a first expansion hold element P10, a first discharge element P11, a vibration suppression hold element P12, and an expansion vibration suppression element P13. Consists of. Among these waveform elements, the first expansion element P9, the first expansion hold element P10, the first discharge element P11, the vibration suppression hold element P12, and the expansion vibration suppression element P13 are respectively the first expansion of the first waveform portion PS1. The same potential difference and time width as the element P2, the first expansion hold element P3, the first discharge element P4, the vibration suppression hold element P5, and the expansion vibration suppression element P6 are set. The third constant potential element P8 is a waveform element that is constant at the intermediate potential Vhm as in the first constant potential element P1, but the generation time is different.

  In the first drive signal COM1, the first expansion element P2, the first expansion hold element P3, the first discharge element P4, the vibration suppression hold element P5, and the expansion vibration suppression element P6 of the first waveform portion PS1 are in the first middle. The dot drive pulse DP1 is configured. Similarly, the first expansion element P9, the first expansion hold element P10, the first discharge element P11, the vibration suppression hold element P12, and the expansion vibration suppression element P13 of the second waveform portion PS2 receive the second middle dot drive pulse DP2. Constitute. These middle dot drive pulses DP1 and DP2 are one type of the first drive pulse of the present invention as described above, and are used in the recording gradation having the largest amount of landing ink per unit area, as will be described later. These middle dot drive pulses DP1 and DP2 have the same waveform shape, and when supplied to the piezoelectric vibrator 21, an ink droplet of an amount corresponding to the middle dot is ejected from the nozzle opening 32.

  The first middle dot drive pulse DP1 will be described as an example. By supplying the first expansion element P2, the piezoelectric vibrator 21 contracts in the longitudinal direction of the element, and the pressure chamber 35 is a reference corresponding to the intermediate potential Vhm (reference potential). The volume expands to the expansion volume corresponding to the first expansion potential Vh1. By this expansion, ink is supplied into the pressure chamber 35 from the reservoir 33 side. The expansion state of the pressure chamber 35 is maintained over the supply period of the first expansion hold element P3.

Thereafter, the first ejection element P4 is supplied and the piezoelectric vibrator 21 expands. By the extension of the piezoelectric vibrator 21, the pressure chamber 35 is rapidly contracted from the expansion volume to the contraction volume corresponding to the contraction potential VL. The ink in the pressure chamber 35 is pressurized by the rapid contraction of the pressure chamber 35, and a predetermined amount of ink droplets are ejected from the nozzle opening 32.
The contraction state of the pressure chamber 35 is maintained over the supply period of the vibration suppression hold element P5. During this time, the ink pressure in the pressure chamber 35, which has decreased due to the ejection of ink droplets, rises again due to its natural vibration. The expansion damping element P6 is supplied in accordance with the rising timing. By supplying the expansion damping element P6, the pressure chamber 35 is expanded and returned to the reference volume, and the ink pressure fluctuation in the pressure chamber 35 is absorbed.

  Further, in the first drive signal COM1, the middle dot drive pulses DP1, DP2 are generated by the first adjustment element P0, the first constant potential element P1, the second constant potential element P7, and the third constant potential element P8. Are connected at the start / end potential (intermediate potential Vhm) so that the middle dot drive pulses DP1 and DP2 are generated at regular intervals across the recording period T. That is, the sum of the generation period of the first adjustment element P0 and the generation period of the first constant potential element P1, and the sum of the generation period of the second constant potential element P7 and the generation period of the third constant potential element P8 are set to the same value. doing.

  As described above, when the middle dot drive pulses DP1 and DP2 are generated at regular intervals across the recording period T, when the middle dot drive pulses DP1 and DP2 are continuously supplied to the piezoelectric vibrator 21, that is, When recording is performed with the recording tone of the large dot having the largest amount of landed ink per unit area, the state of the meniscus (the free surface of the ink exposed at the nozzle openings 32) at the start of supply can be made constant. Thereby, the flight of ink droplets can be stabilized, and the image quality can be improved. Further, the drive pulses included in the first drive signal COM1 are only the middle dot drive pulses DP1 and DP2. For this reason, the generation interval of these middle dot drive pulses DP1 and DP2 can be narrowed within a range where the recording head 8 (piezoelectric vibrator 21) can respond. In this way, high-frequency driving of the recording head 8 can be realized in the recording gradation of large dots, and the performance can be maximized.

  Next, the second drive signal COM2 will be described.

The second adjustment element P20 is configured by a waveform element that is constant at the intermediate potential Vhm, similarly to the first adjustment element P0. The second adjustment element P20 is also supplied to the piezoelectric vibrator 21 in order to adjust the vibrator potential to the intermediate potential Vhm at the beginning of the recording cycle T.
In the present embodiment, at the start of the recording cycle T, either the second adjustment element P20 or the first adjustment element P0 is supplied to the piezoelectric vibrator 21. For this reason, the generation period t20 of the second adjustment element P20 is set to the same time width as the generation period t10 of the first adjustment element P0.

  The third waveform portion PS3 is configured by a fourth constant potential element P21. The fourth constant potential element P21 is a waveform element that is constant at the intermediate potential Vhm.

  The fourth waveform portion PS4 includes a fifth constant potential element P22, a minute vibration first expansion element P23, and a minute vibration constant potential element P24, and is used as a front minute vibration waveform (a kind of minute vibration waveform in the present invention). Function. The fifth constant potential element P22 is a waveform element that is constant at the intermediate potential Vhm, and is generated for a very short time. The fine vibration first expansion element P23 is a waveform element that raises the potential with a relatively gentle constant gradient from the intermediate potential Vhm to the fine vibration expansion potential Vh2, and the fine vibration constant potential element P24 has a constant waveform at the fine vibration expansion potential Vh2. Is an element.

  The fifth waveform portion PS5 includes a front connection constant potential element P25, a connection element P26, and a rear connection constant potential element P27, and functions as a connection waveform element in the present invention. The front-side connection constant potential element P25 is a waveform element that is constant at the micro-vibration expansion potential Vh2, and is generated for a very short time. The connection element P26 is a waveform element that drops the potential with a steep slope from the micro-vibration expansion potential Vh2 to the intermediate potential Vhm. The rear connection constant potential element P27 is a waveform element that is constant at the intermediate potential Vhm, and is generated for a very short time. The fifth waveform portion PS5 is a portion for connecting two waveform elements having different terminal potential and starting potential, and is not supplied to the piezoelectric vibrator 21. Therefore, the gradient of the connection element P26 can be set steeply to the maximum controllable. Thereby, the front and rear waveform elements (the fine vibration constant potential element P24, the sixth constant potential element P28 of the sixth waveform portion PS6) can be generated at a very short time interval.

The sixth waveform portion PS6 includes a sixth constant potential element P28, a second expansion element P29, a second expansion hold element P30, a second discharge element P31, and a front discharge hold element P32. The sixth constant potential element P28 is a waveform element that is constant at the intermediate potential Vhm, and is generated for a very short time. The second expansion element P29 is a waveform element that rapidly increases the potential from the intermediate potential Vhm to the second expansion potential Vh3, and the second expansion hold element P30 is a waveform element that is constant at the second expansion potential Vh3. The second discharge element P31 is a waveform element that rapidly decreases the potential from the second expansion potential Vh3 to the discharge potential Vh4, and the front discharge hold element P32 is a waveform element that is constant at the discharge potential Vh4.
Note that the ejection potential Vh4 in the present embodiment is set to the same potential as the micro-vibration expansion potential Vh2 in the fourth waveform portion PS4.

  The seventh waveform portion PS7 includes a rear discharge hold element P33, a contraction damping element P34, and a seventh constant potential element P35. The rear discharge hold element P33 is a waveform element that is constant at the discharge potential Vh4, and is generated for a very short time. The contraction damping element P34 is a waveform element that lowers the potential with a relatively gentle constant gradient from the discharge potential Vh4 to the intermediate potential Vhm, and the seventh constant potential element P35 is a waveform element that is constant at the intermediate potential Vhm. The seventh constant potential element P35 is generated from the end of the contraction damping element P34 to the end of the recording period T.

  In the second drive signal COM2, the second expansion element P29, the second expansion hold element P30, the second discharge element P31, the discharge hold elements P32 and P33, and the contraction control of the sixth waveform section PS6 and the seventh waveform section PS7. The vibrating element P34 constitutes the small dot drive pulse DP3. The small dot drive pulse DP3 is a kind of small droplet drive pulse in the present invention, and can eject a smaller amount of ink droplets than the middle dot drive pulses DP1 and DP2. When the small dot drive pulse DP3 is supplied to the piezoelectric vibrator 21, a very small amount of ink droplet corresponding to the small dot is ejected from the nozzle opening 32.

  That is, the supply of the second expansion element P29 causes the piezoelectric vibrator 21 to rapidly contract in the longitudinal direction of the element and rapidly expand from the reference volume corresponding to the intermediate potential Vhm to the second expansion volume corresponding to the second expansion potential Vh3. . Due to this expansion, a relatively strong negative pressure is generated in the pressure chamber 35, and the meniscus is largely drawn toward the pressure chamber 35. The expansion state of the pressure chamber 35 is maintained over the supply period of the second expansion hold element P30. During this time, the moving direction of the central portion of the meniscus is reversed in the discharge direction, and the central portion is raised in a columnar shape.

  Thereafter, the second ejection element P31 is supplied and the piezoelectric vibrator 21 expands. By the extension of the piezoelectric vibrator 21, the pressure chamber 35 is rapidly contracted from the second expansion volume to the discharge volume corresponding to the discharge potential Vh4. Then, the ink in the pressure chamber 35 is pressurized by the rapid contraction of the pressure chamber 35 and the growth of the columnar portion is promoted, and the columnar portion is broken off in the middle and ejected as ink droplets.

  Following the second discharge element P31, the front discharge hold element P32 and the rear discharge hold element P33 are supplied, and then the contraction damping element P34 is supplied. The contraction damping element P34 contracts the pressure chamber 35 so as to compensate for the ink pressure in the pressure chamber 35 that has decreased due to the ejection of ink droplets. That is, the supply of the contraction damping element P34 causes the pressure chamber 35 to contract to the reference volume and absorbs the pressure fluctuation of the ink in the pressure chamber 35.

  Further, in the second drive signal COM2, the fine vibration first expansion element P23, the fine vibration constant potential element P24, the rear discharge hold element P33, and the contraction vibration suppression element of the fourth waveform portion PS4 and the seventh waveform portion PS7. P34 constitutes a fine vibration pulse. When this fine vibration pulse is supplied to the piezoelectric vibrator 21, a pressure fluctuation that does not cause ink droplets to be ejected is applied to the ink in the pressure chamber 35, causing the meniscus to vibrate.

  That is, the piezoelectric vibrator 21 is gradually contracted in the longitudinal direction of the element by the supply of the fine vibration first expansion element P23. As a result, the pressure chamber 35 expands relatively slowly from the reference volume corresponding to the intermediate potential Vhm to the microvibration expansion volume corresponding to the microvibration expansion potential Vh2. Due to this expansion, a relatively weak negative pressure is generated in the pressure chamber 35, and the meniscus is slightly pulled toward the pressure chamber 35. The expanded state of the pressure chamber 35 is maintained until the end of the supply of the rear discharge hold element P33. During this time, the meniscus vibrates slightly between the pressure chamber side and the discharge side in the vicinity of the nozzle opening 32. The finely vibrating meniscus disperses the thickened ink in the vicinity of the nozzle openings 32 and prevents ink thickening. Furthermore, the pressure chamber 35 contracts to the reference volume by supplying the contraction damping element P34. By this contraction, the ink in the pressure chamber 35 is slightly pressurized, and the meniscus moves slightly to the ejection side. Microvibration is continued by the movement of the meniscus.

  The small dot drive pulse DP3, the front side fine vibration waveform (PS4), and the waveform elements (P23 to P34) constituting the connection waveform element (PS5) are partially generated in the middle dot drive pulse. It overlaps with the generation period of each waveform element (P2 to P6, P9 to P13) constituting DP1 and DP2. For example, the generation period of the fine vibration first expansion element P23 of the front fine vibration waveform PS4 overlaps with the generation periods of the first expansion hold element P3 and the first ejection element P4 in the first middle dot drive pulse DP1. In addition, the generation period of the second expansion element P29 of the small dot drive pulse DP3 partially overlaps the generation period of the expansion damping element P6 of the first middle dot drive pulse DP1. Further, the generation period of the contraction damping element P34 of the small dot drive pulse DP3 overlaps with the generation period of the first expansion element P9 of the second middle dot drive pulse DP2 at the end portion.

  As described above, when the drive pulses DP1 to DP3 and the waveform elements PS4 and PS5 are separately provided for the drive signals COM1 and COM2 and generated by superimposing them in time, the recording period T has a limited length. However, it is possible to efficiently arrange the drive pulses DP1 to DP3 and the fine vibration pulse. As a result, high frequency driving of the recording head 8 can be realized.

  Further, the generation timing of the small dot drive pulse DP3 is set in the middle between the first middle dot drive pulse DP1 and the second middle dot drive pulse DP2. Specifically, the generation timing of the second ejection element P31 in the small dot drive pulse DP3 is the same as the generation timing of the first ejection element P4 in the first middle dot drive pulse DP1 and the first ejection element P11 in the second middle dot drive pulse DP2. It is set to exactly the middle of the generation timing. This is to improve the image quality.

  In the present embodiment, both the first middle dot drive pulse DP1 and the second middle dot drive pulse DP2 are supplied to the piezoelectric vibrator 21 in the large dot recording gradation, and the second middle dot drive is performed in the middle dot recording gradation. The pulse DP2 is supplied to the piezoelectric vibrator 21. Further, the small dot drive pulse DP3 is supplied to the piezoelectric vibrator 21 in the small dot recording gradation.

Here, if the small dot drive pulse DP3 is generated between the first middle dot drive pulse DP1 and the second middle dot drive pulse DP2, the recording gradation is switched between the previous recording cycle T and the current recording cycle T. Ink droplet ejection intervals can be made uniform. For example, when a small dot is recorded in the previous recording period T, a large dot is recorded in the current recording period T, a large dot is recorded in the previous recording period T, and a small dot is recorded in the current recording period T. The discharge interval can be aligned.
Thereby, the state of the meniscus in the current recording cycle T becomes constant, and the ejection of ink droplets can be stabilized, thereby improving the image quality.

  Next, multi-gradation control according to the present embodiment will be described with reference to FIGS. In this multi-gradation control, the switches 49 and 50 are controlled by switch control means (decoder 45, control logic 46, and level shifters 47 and 48, and so on). The switches 49 and 50 supply the selected drive signals COM1 and COM2 to the piezoelectric vibrator 21. That is, the first drive signal COM1 and the second drive signal COM2 are not supplied to the piezoelectric vibrator 21 at the same time. This is for stabilizing the vibrator potential.

  First, the case of non-recording will be described. In this case, the decoder 45 generates the first waveform selection data [000] and the second waveform selection data [111001] by translating the non-recorded gradation data [00]. Then, the switch control means controls the operation of the first switch 49 and the second switch 50 based on the generated waveform selection data, and supplies the first drive signal COM1 and the second drive signal COM2 to the piezoelectric vibrator 21. To control.

  That is, the second adjustment element P20 is supplied to the piezoelectric vibrator 21 during the period t10 (t20). Thereby, the vibrator potential is adjusted to the intermediate potential Vhm. Here, the first adjustment element P0 and the second adjustment element P20 are selected according to the waveform section (waveform element) to be supplied next, and the selected elements are supplied to the piezoelectric vibrator 21. Specifically, the first adjustment element P0 is selected if the waveform portion to be supplied next is the first drive signal COM1, and the second adjustment element P20 is selected if the waveform portion is the second drive signal COM2. The This is to reduce the number of times each switch 49, 50 is activated. That is, when the number of operations of the switches 49 and 50 is reduced, the drive signal supplied to the piezoelectric vibrator 21 is stabilized and the operation of the piezoelectric vibrator 21 is stabilized.

Then, the first switch 49 is controlled to be disconnected in the periods t11 and t12, and the second switch 50 is controlled to be connected in the periods t21, t22, and t25. Accordingly, the third waveform portion PS3 is supplied to the piezoelectric vibrator 21 in the period t21, the fourth waveform section PS4 is supplied to the piezoelectric vibrator 21 in the period t22, and the seventh waveform section PS7 is supplied to the piezoelectric vibrator 21 in the period t25. That is, as shown by a thick line in FIG. 4, micro vibration pulses (P23, P24, P33, P34) are supplied to the piezoelectric vibrator 21.
As a result, the thickened ink in the vicinity of the nozzle opening 32 is dispersed, and the thickening of the ink is prevented.

  In the present embodiment, by aligning the micro-vibration expansion potential Vh2 and the discharge potential Vh4 to the same potential, some waveform elements (P33, P34) constituting the small dot drive pulse DP3 are part of the micro-vibration pulse. That is, it is used as a rear side fine vibration waveform. Further, the fine vibration waveform PS4 is incorporated in the second drive signal COM2 using the connection waveform element PS5. Accordingly, the small dot drive pulse DP3 and the minute vibration pulses (P23, P24, P33, P34) can be efficiently incorporated within the limited recording cycle T.

  Next, a case where a small dot is recorded will be described. In this case, the decoder 45 generates the first waveform selection data [000] and the second waveform selection data [110011] by translating the small dot gradation data [01]. Then, the switch control means controls the supply of the first drive signal COM1 and the second drive signal COM2 to the piezoelectric vibrator 21 based on the generated waveform selection data.

That is, in the period t10 (t20), the second adjustment element P20 is supplied to the piezoelectric vibrator 21, and the vibrator potential is adjusted to the intermediate potential Vhm. Then, the first switch 49 is controlled to be disconnected in the period t11 and the period t12, and the second switch 50 is controlled to be connected in the period t21, the period t24, and the period t25. As a result, as shown by a thick line in FIG. 5, the third waveform part PS3 is supplied to the piezoelectric vibrator 21 in the period t21, the sixth waveform part PS6 is supplied in the period t24, and the seventh waveform part PS7 is supplied to the piezoelectric vibrator 21 in the period t25. . That is, the small dot drive pulse DP3 is supplied to the piezoelectric vibrator 21.
As a result, a very small amount of ink droplet is ejected from the nozzle opening 32 by the small dot drive pulse DP3.

  Next, a case where middle dots are recorded will be described. In this case, the decoder 45 generates the first waveform selection data [001] and the second waveform selection data [110000] by translating the middle dot gradation data [10]. Then, the switch control means controls the supply of the first drive signal COM1 and the second drive signal COM2 to the piezoelectric vibrator 21 based on the generated waveform selection data.

  That is, in the period t10 (t20), the second adjustment element P20 is supplied to the piezoelectric vibrator 21, and the vibrator potential is adjusted to the intermediate potential Vhm. In the period t11, the first switch 49 is disconnected, and in the period t21, the second switch 50 is connected. As a result, as shown by a thick line in FIG. 6, the third waveform portion PS3 of the second drive signal COM2 is supplied to the piezoelectric vibrator 21, and the vibrator potential is maintained at the intermediate potential Vhm by the fourth constant potential element P21. .

  In the subsequent period t22 to t24, since the second switch 50 is controlled to be in a disconnected state, the first drive signal COM1 and the second drive signal COM2 are supplied to the piezoelectric vibrator 21 from the start of t22 to immediately before the start of t12. Is not supplied. As a result, as indicated by a thin line in FIG. 6, the vibrator potential is maintained at the intermediate potential Vhm that is the potential immediately before cutting. In this case, since the fourth constant potential element P21 is supplied to the piezoelectric vibrator 21 in the previous period t21, the drive signal non-supply period is relatively short.

  Then, in the period t12, the first switch 49 is controlled to be connected. As a result, as shown by a thick line in FIG. 6, the second waveform portion PS2 of the first drive signal COM1 is supplied to the piezoelectric vibrator 21, and a small amount of ink corresponding to the middle dot is supplied by the supply of the second middle dot drive pulse DP2. Drops are ejected.

  As described above, in the present embodiment, in the case of middle dot recording gradation, some waveform elements (third constant potential element P8, first expansion element P9, first expansion) constituting the first drive signal COM1. A combination of a hold element P10, a first discharge element P11, a vibration suppression hold element P12, an expansion vibration suppression element P13) and a part of waveform elements (fourth constant potential element P21) constituting the second drive signal COM2. This is supplied to the vibrator 21. That is, in the period (period t11) in which the first drive signal COM1 cannot be supplied due to the relationship of the waveform elements, the vibrator potential is maintained at the intermediate potential Vhm by supplying the fourth constant potential element P21 of the second drive signal COM2. ing.

This is to shorten the non-supply period of the drive signals COM1 and COM2 to the piezoelectric vibrator 21 as much as possible. That is, when the printer is used under high humidity or when the insulation resistance of the piezoelectric body is reduced due to overuse of the piezoelectric vibrator 21 for a long period of time, the charge holding power in the piezoelectric vibrator 21 is reduced. There is a fear. When the charge holding power is reduced, the vibrator potential gradually decreases due to the discharge in the non-supply period. For this reason, when the non-supply period is long, the descending width of the vibrator potential increases, and the potential difference between the drive signal potential and the vibrator potential becomes large when the drive signal is supplied next time. In this case, the piezoelectric vibrator 21 is suddenly deformed and ink droplets are accidentally ejected.
If the non-supply period of the drive signals COM1 and COM2 is shortened as much as possible as in this embodiment, even if the charge holding power is reduced, the descending width of the vibrator potential can be reduced. The drive signals COM1 and COM2 can be supplied without any trouble.

  Next, a case where large dots are recorded will be described. In this case, the decoder 45 generates the first waveform selection data [111] and the second waveform selection data [000000] by translating the large dot gradation data [11]. Then, the switch control means controls the supply of the first drive signal COM1 and the second drive signal COM2 to the piezoelectric vibrator 21 based on the generated waveform selection data.

That is, in the period t10 (t20), the first adjustment element P0 is supplied to the piezoelectric vibrator 21, and the vibrator potential is adjusted to the intermediate potential Vhm. In the period t11 and the period t12, the first switch 49 is controlled to be in the connected state, while in the period t21 to the period t25, the second switch 50 is controlled to be in the disconnected state. Accordingly, the first waveform portion PS1 is supplied to the piezoelectric vibrator 21 in the period t11, and the second waveform section PS2 is supplied to the piezoelectric vibrator 21 in the period t12. That is, as shown by a thick line in FIG. 7, the first middle dot drive pulse DP1 and the second middle dot drive pulse DP2 are supplied to the piezoelectric vibrator 21.
As a result, a small amount of ink droplets generated by the middle dot driving pulse are ejected twice from the nozzle opening 32, and large dots are recorded by these ink droplets.

In the present embodiment, the first drive signal COM1 includes only the middle dot drive pulses DP1 and DP2 used in the large dot recording gradation having the largest ink amount per unit area. In other words, drive pulses (small dot drive pulse DP3 and fine vibration pulse) used only for other recording gradations are included in other drive signals COM2.
For this reason, the generation interval of these middle dot drive pulses DP1 and DP2 can be freely set without being restricted by other drive pulses. Thereby, the generation interval of the middle dot drive pulses DP1 and DP2 can be determined based on the response frequency of the recording head 8 (piezoelectric vibrator 21), and the performance of the recording head 8 can be exhibited sufficiently.

  Note that the recording gradation of the large dots is set at the time of so-called solid recording in which a predetermined area on the recording paper is filled because the ink amount per unit area is the largest. From the viewpoint of increasing the recording speed, it is important to increase the recording speed during the solid recording. This is because the other recording gradations are not used for solid recording, and the driving frequency of the recording head 8 at the other recording gradations can be set lower than the driving frequency at the time of large dot recording.

  As described above, in the present embodiment, the two middle dot drive pulses DP1 and DP2 used in the large dot recording gradation are included in the first drive signal COM1, and the other drive pulses are included in the second drive signal COM2. Therefore, the generation interval of the middle dot drive pulses DP1 and DP2 can be determined according to the response frequency of the recording head 8. Accordingly, the piezoelectric vibrator 21 can be driven at a high frequency, and the performance of the recording head 8 can be sufficiently exhibited.

  Further, since the generation period of the middle dot drive pulses DP1 and DP2 and the generation period of other drive pulses overlap at least partially, the recording cycle T is shorter than when a plurality of drive pulses are connected in series. Can be set. Also in this respect, the piezoelectric vibrator 21 can be driven at a high frequency, and the performance of the recording head 8 can be sufficiently exhibited.

  In addition, since the second drive signal includes a composite pulse in which the small dot drive pulse DP3 and the front micro-vibration waveform PS4 are connected by the connection waveform element PS5, a plurality of types of drive pulses are included in the second drive signal COM2. Can be incorporated efficiently.

  Furthermore, since a part of the waveform elements constituting the first drive signal COM1 and a part of the waveform elements constituting the second drive signal COM2 are combined and supplied to the piezoelectric vibrator 21, each drive signal includes It is possible to drive with a new pattern that is not specified. For example, the non-supply period of the drive signal to the piezoelectric vibrator 21 can be shortened as much as possible. Thereby, complicated control can be realized while the recording head 8 is driven at high frequency.

  By the way, the present invention is not limited to the above embodiment, and various modifications can be made based on the description of the scope of claims.

  In the above embodiment, the first switch 49 and the second switch 50 provided for each type of generated drive signal are used to selectively supply the drive signals COM1 and COM2 to the piezoelectric vibrator 21. Although illustrated, it is not limited to this configuration. For example, the drive signals COM1 and COM2 may be selectively supplied to the piezoelectric vibrator 21 by the changeover switch 61 shown in FIG.

  The illustrated changeover switch 61 functions as second switch means (a kind of switch means of the present invention) and is provided for each piezoelectric vibrator 21. The changeover switch 61 includes a first input contact 61a, a second input contact 61b and an off contact 61c provided corresponding to the type of drive signal to be generated, and an output terminal 61d that is electrically connected to the piezoelectric vibrator 21. And one of the contacts 61a to 61c is selectively electrically connected to the output terminal 61d. A supply line for the first drive signal COM1 is electrically connected to the first input contact 61a, a supply line for the second drive signal COM2 is electrically connected to the second input contact 61b, and the off contact 61c is Electrically disconnected.

  In the changeover switch 61, the drive signals COM1 and COM2 can be selectively supplied to the piezoelectric vibrator 21 by switching the contacts 61a to 61c conducted to the output terminal 61d. That is, when the first input contact 61a is conducted to the output terminal 61d, the first drive signal COM1 can be supplied, and when the second input contact 61b is conducted to the output terminal 61d, the second drive signal COM2 can be supplied. Further, when the off contact 61c is made conductive to the output terminal 61d, neither the first drive signal COM1 nor the second drive signal COM2 is supplied.

  The operation of the selector switch 61 is controlled by a decoder 62 and a switch control circuit 63 (corresponding to the switch control means of the present invention). That is, the decoder 62 functions as a switch switching data generating means, and translates the recording data (gradation data) to translate the first input contact 61a ([1]), the second input contact 61b ([2]), and the OFF contact. 61c ([0]) is generated to generate switch switching data. The switch switching data is output to the switch control circuit 63 in synchronization with the timing from the control logic 46 ′. Thereby, similarly to the above-described embodiment, the drive signals COM1 and COM2 can be selectively supplied to the piezoelectric vibrator 21.

Regarding the drive signal, in the above-described embodiment, the first drive signal COM1 having the two middle dot drive pulses DP1 and DP2 within one recording period T is exemplified, but the present invention is not limited to this configuration.
For example, the first drive signal COM1 may be a signal having one large dot drive pulse within one recording period T, that is, a drive pulse that can eject an ink droplet of an amount corresponding to the large dot. In this case, the second drive signal COM2 includes, for example, a composite pulse composed of a middle dot drive pulse, a small dot drive pulse, and a fine vibration pulse (a kind of the second drive pulse of the present invention).
Further, three or more normal dot drive pulses, that is, a drive pulse capable of ejecting an ink amount of a small dot by one may be included. In this case, the second drive signal COM2 includes, for example, a fine vibration pulse (a kind of the second drive pulse of the present invention).

In the above-described embodiment, two types of drive signals COM1 and COM2 are exemplified. However, the present invention can be similarly implemented by generating three or more types of drive signals. For example, a dedicated drive signal may be generated for each recording gradation to obtain a total of four types of drive signals.
In this case, one type of drive signal used in the large dot recording gradation is the first drive signal of the present invention, and three types of drive signals used in the other recording gradation are the second drive signal of the present invention.

  In addition, regarding the pressure generating element, the above embodiment has described the case where the so-called longitudinal vibration mode piezoelectric vibrator 21 is used, but the present invention is not limited to this. That is, various elements can be used as long as they can hold the previous potential when the potential is changed by supplying the drive pulse and the supply of the drive pulse is cut off. For example, a so-called flexural vibration mode piezoelectric vibrator or an electrostatic actuator may be used.

The present invention is not limited to a printer, and can be applied to various ink jet recording apparatuses such as a plotter, a facsimile machine, and a copier.
The present invention can also be applied to liquid ejecting apparatuses other than the recording apparatus. For example, a display manufacturing apparatus that manufactures color filters such as liquid crystal displays, an electrode manufacturing apparatus that forms electrodes such as organic EL (Electro Luminescence) displays and FEDs (surface emitting displays), and chips that manufacture biochips (biochemical elements) The present invention can also be applied to a manufacturing apparatus and a micropipette that supplies an accurate amount of a very small amount of sample solution.
In the display manufacturing apparatus, a solution of each color material of R (Red), G (Green), and B (Blue) is discharged from the color material ejecting head. Moreover, in an electrode manufacturing apparatus, a liquid electrode material is discharged from an electrode material ejection head. In the chip manufacturing apparatus, a bioorganic solution is discharged from a bioorganic ejecting head.

It is a functional block diagram of an ink jet printer. 2 is a cross-sectional view illustrating a configuration of a recording head in a longitudinal vibration mode. FIG. It is a figure explaining the drive signal which a drive signal generation circuit generates, and supply control of this drive signal. It is a figure explaining supply control of a drive signal at the time of non-recording. It is a figure explaining supply control of a drive signal at the time of small dot recording. It is a figure explaining supply control of a drive signal at the time of middle dot recording. It is a figure explaining supply control of a drive signal at the time of large dot recording. It is a block diagram explaining the other example of a switch means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printer controller, 2 ... Print engine, 3 ... External I / F, 4 ... RAM, 5 ... ROM, 6 ... Control part, 7 ... Oscillation circuit, 8 ... Recording head, 9 ... Drive signal generation circuit, 10 ... Internal I / F, 11 ... carriage mechanism, 12 ... paper feed mechanism, 21 ... piezoelectric vibrator, 22 ... fixed plate, 23 ... flexible cable, 24 ... vibrator unit, 25 ... case, 26 ... flow path unit, 27 ... housing Empty part, 28 ... Island part, 29 ... Flow path forming substrate, 30 ... Nozzle plate, 31 ... Vibrating plate, 32 ... Nozzle opening, 33 ... Reservoir, 34 ... Ink supply port, 35 ... Pressure chamber, 36 ... Nozzle communication port , 37 ... support plate, 38 ... resin film, 41 ... first shift register, 42 ... second shift register, 43 ... first latch circuit, 44 ... second latch circuit, 45 ... decoder, 46, 46 '... control logic Click, 47 ... first level shifter, 48 ... second level shifter, 49 ... first switch, 50 ... second switch, 61 ... change-over switch, 62 ... decoder, 63 ... switch control circuit

Claims (5)

A pressure generating element capable of causing pressure fluctuation in the liquid in the pressure chamber, and a liquid ejecting head having a nozzle opening communicating with the pressure chamber;
Drive signal generating means for repeatedly generating a drive signal including a drive pulse every discharge cycle,
In a liquid ejecting apparatus capable of controlling the supply of a driving pulse to a pressure generating element according to the landing gradation and controlling the discharge of a droplet from a nozzle opening,
The drive signal generating means has only a first drive pulse used at a landing gradation having the largest amount of landing liquid per unit area, and generates the first drive pulse at equal intervals; A series of second drive signals having a second drive pulse used in other landing gradations, and the generation period of the first drive pulse and the generation period of the second drive pulse are overlapped at least partially; A liquid ejecting apparatus.   The liquid ejecting apparatus according to claim 1, wherein the second drive pulse is generated in the middle between adjacent first drive pulses.   3. The liquid ejecting apparatus according to claim 1, wherein the second driving pulse is a small droplet driving pulse having a smaller discharge liquid amount than the first driving pulse. 4.   The said 2nd drive pulse is a fine vibration pulse which gives a pressure fluctuation to the liquid in a pressure chamber to such an extent that a droplet is not discharged, and makes a meniscus vibrate finely. Liquid ejector. The second driving pulse supplies the pressure generating element with a small droplet driving pulse having a smaller discharge volume than the first driving pulse and a fine vibration waveform that fluctuates the volume of the pressure chamber to the extent that the droplet is not discharged. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a composite pulse connected by connection waveform elements that are not connected.

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