JP2003237113A - Liquid injection device - Google Patents

Abstract

(57) [Problem] To drive a liquid jet head at a higher frequency. A drive signal generation circuit includes a first drive signal CO.
M1 and the second drive signal COM2 are separately generated. First
The drive signal COM1 is a signal 2 used for recording a large dot.
It is composed of only two middle dot drive pulses DP1 and DP2. The other drive pulse, that is, the small dot drive pulse DP3 and the front-side fine vibration waveform PS4 are connected to each other by the connection waveform element P
The composite pulse connected in S5 is included in the second drive signal. Then, the first switch and the second switch are controlled by the decoder, the control logic, and each level shifter,
The waveform parts PS1 to PS7 forming the first drive signal COM1 and the second drive signal COM2 are combined and supplied to the piezoelectric vibrator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, a display manufacturing apparatus, an electrode forming apparatus, a biochip manufacturing apparatus or the like, which is equipped with a liquid ejecting head capable of ejecting various liquids as liquid droplets. The present invention relates to an apparatus, and more particularly, to an apparatus capable of controlling the ejection of liquid droplets from a nozzle opening by controlling the supply of a drive pulse to a pressure generating element according to the landing gradation.

[0002]

2. Description of the Related Art A liquid ejecting apparatus is an apparatus for ejecting liquid in a droplet state from a nozzle opening. For example, an image recording apparatus for ejecting ink droplets to record an image or the like on a recording sheet,
An electrode forming device that discharges a liquid electrode material onto a substrate to form an electrode, a biochip manufacturing device that discharges a biological sample to manufacture a biochip, or a micropipette that discharges a predetermined amount of sample into a container is proposed. Has been done.

In this liquid ejecting apparatus, the amount of liquid droplets ejected from the nozzle opening can be changed in order to achieve both high-speed processing of the landing target on which the liquid droplets land and high accuracy of landing amount control. The one that has been proposed. For example,
In an ink jet recording apparatus, which is a kind of this liquid ejecting apparatus, a single drive signal that includes a plurality of drive pulses in a single recording cycle is generated and driven according to recording data (gradation data). By supplying a necessary portion of the signal to the pressure generating element, the amount of ink ejected from the nozzle opening is changed (for example, refer to Patent Document 1).

[0004]

[Patent Document 1] Japanese Unexamined Patent Publication No. 10-81012 (No. 9)
(Page, Fig. 9)

[0005]

By the way, in the conventional structure in which the required portion 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 jet head. . That is, the liquid ejection head (pressure generating element) has to be driven at a frequency lower than the maximum frequency that can be driven due to the relationship of including a plurality of drive pulses in one ejection cycle.

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

[0007]

DISCLOSURE OF THE INVENTION The present invention has been proposed in order to achieve the above-mentioned object, and has a pressure generating element capable of causing a pressure fluctuation in a liquid in a pressure chamber and a nozzle opening communicating with the pressure chamber. A liquid ejecting head having: a drive signal generating means for repeatedly generating a drive signal including a drive pulse for each ejection cycle; a switch means capable of controlling the supply of the drive signal to the pressure generating element; and an operation of the switch means. In a liquid ejecting apparatus comprising a switch control unit for controlling, controlling the supply of a drive pulse to a pressure generating element according to the landing gradation, and controlling the discharge of droplets from a nozzle opening,
The drive signal generating means has only a first drive pulse used in a landing gradation having the largest amount of landing liquid per unit area, and generates a first drive pulse at even intervals. A series of second drive signals having a second drive pulse used for another landing gradation is generated, and the generation period of the first drive pulse and the generation period of the second drive pulse are overlapped at least partially. The switch control means is configured to selectively supply each drive signal to the pressure generating element.

In this configuration, it is preferable that a plurality of first drive pulses be generated within one ejection cycle. Further, the second drive pulse causes a small droplet drive pulse having a smaller amount of ejected liquid than the first drive pulse, or a pressure fluctuation is applied to the liquid in the pressure chamber to the extent that the droplet is not ejected, and the meniscus vibrates slightly. It is preferably a vibrating pulse.
Further, the above “landing gradation” is information indicating the amount of landing of the liquid per unit area, and is a superordinate concept of “recording gradation” in the printing apparatus. The “meniscus” is the free surface of the liquid exposed at the nozzle openings.

According to the present invention, the generation period of the first drive pulse and the generation period of the second drive pulse are at least partially overlapped with each other, and the first drive pulse and the second drive pulse are combined by the switch control means. Since the piezoelectric vibrator is selectively supplied, the generation interval of the first drive pulse can be freely set without being restricted by the second drive pulse. Therefore, the first
The drive pulse generation interval can be set according to the response frequency of the pressure generating element. As a result, the liquid jet head can be driven at a higher frequency.

In the above invention, the second driving pulse includes a small droplet driving pulse having a discharge liquid amount smaller than that of the first driving pulse, and a fine vibration waveform for changing the volume of the pressure chamber to the extent that the droplet is not discharged. Is a composite pulse connected by a connection waveform element that is not supplied to the pressure generating element, and the switch control means supplies the minute vibration waveform and a part of the second drive pulse to the pressure generating element in the non-ejection landing gradation. However, a configuration in which the meniscus is slightly vibrated is preferable. According to the present invention, a plurality of types of drive pulses can be efficiently included in a limited ejection cycle.

In the above invention, it is preferable that the small droplet drive pulse is generated in the middle of adjacent first drive pulses. According to the present invention, it is possible to prevent the deviation of the discharge intervals of the droplets.

In the above invention, the second drive signal is
Including a constant potential element that is constant at the starting potential of the first drive pulse,
The switch control means is preferably configured to supply the constant potential element to the pressure generating element during the non-supply period of the first drive pulse. According to the present invention, the constant potential element is supplied to the pressure generating element during the non-supply period of the first drive pulse. As a result, the pressure generating element is maintained at the starting potential of the first drive pulse, and the first drive pulse can be supplied smoothly.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Note that the following description will be given by taking an inkjet printer as an example. This printer is
Liquid ink (a kind of the liquid of the present invention) is made into a state of a droplet and ejected from a recording head (a kind of the liquid ejecting head of the present invention), and is a kind of the liquid ejecting apparatus of the present invention.

The printer illustrated in FIG. 1 comprises 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 higher-level device) from a host computer (not shown), and various data. RAM 4 for storing data, ROM 5 for storing various data processing routines, a control unit 6 including a CPU, and an oscillator circuit 7 for generating a clock signal (CK).
And a drive signal (COM1, CO
A drive signal generation circuit 9 for generating M2) and an interface 10 (hereinafter referred to as an internal I / F 10) for transmitting print data, a drive signal and the like to the print engine 2 are provided.

The external I / F 3 receives, from a host computer or the like, print data including any one data of a character code, a graphic function, image data or a plurality of data. Also, the external I / F3 is
It outputs a busy signal (BUSY), an acknowledge signal (ACK), etc. 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. The receive buffer has an external I /
The print data received from F3 from the host computer is temporarily stored. The intermediate buffer stores the intermediate code data converted into the intermediate code by the control unit 6. The print data sent to the print head 8 (a type of second control data sent to the liquid jet head) is expanded in the output buffer. The ROM 5 also stores various control routines executed by the control unit 6, font data and graphic functions, various procedures, and the like.

The drive signal generating circuit 9 corresponds to the drive signal generating means of the present invention, and includes a first drive signal generating section 9A (first drive signal generating means) capable of generating the first drive signal COM1.
The second drive signal generation unit 9B (second drive signal generation means) capable of generating the second drive signal COM2 is provided. Then, 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 cycle T, and is repeatedly generated in each recording cycle T. Here, the middle dot drive pulses DP1, DP2
Is a drive pulse for ejecting an amount of ink droplets (a kind of medium droplet) corresponding to the middle dot, and corresponds to a kind of the first drive pulse of the present invention. Also, the second drive signal C
The OM2 has one composite pulse (a kind of the second drive pulse of the present invention) in which one of the small drive pulses DP3 and the front side micro-vibration waveform (PS4) is connected by the connection waveform element (PS5) within one recording cycle T. A series of signals, the recording cycle T
It is repeatedly generated every time. The recording cycle T is a repeating unit of the drive signal COM and is a kind of ejection cycle in the present invention. In addition, these drive signals COM1, C
The OM2 will be described later in detail.

The control unit 6 controls signal generation for the drive signal generation circuit 9 and expands print data from the host computer into print data to be sent to the print head 8. Then, at the time of developing the print data, the control unit 6 first reads the print data in the reception buffer, converts the print data into an intermediate code, and stores the intermediate code data in the intermediate buffer. Next, the control unit 6 analyzes the intermediate code data read from the intermediate buffer and performs RO
The intermediate code data is expanded into recording data for each dot by referring to the font data and graphic function in M5.

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

The control section 6 constitutes a part of the timing signal generating means, and the recording head 8 receives a latch signal (LAT) and a channel signal (CH-) through the internal I / F 10.
A, CH-B) are supplied. The latch pulse and the channel pulse included in the latch signal and the channel signal define the supply start timing of the plurality of waveform portions and the adjustment elements (PS1 to PS7, P0, P20) that form the drive signals COM1 and COM2.

Specifically, as shown in FIG. 3, the latch pulse LAT1 is used for the vibrator charging period (period t10, period t).
20) defines the supply start timing of the adjustment elements P0 and P20 generated in 20). Also, the first channel signal CH-
The first channel pulse CH11 in A is the first waveform section PS generated in the period t11 of the first drive signal COM1.
The supply start timing of 1 is defined, and the second channel pulse CH12 is the second waveform portion PS generated in the period t12.
2 specifies the supply start timing. Similarly, the first channel pulse CH in the second channel signal CH-B
21 defines the supply start timing of the third waveform portion PS3 generated in the period t21 of the second drive signal COM2,
The channel pulse CH22 defines the supply start timing of the fourth waveform section PS4 generated in the period t22, and the third channel pulse CH23 is the fifth generated in the period t23.
The supply start timing of the waveform section PS5 is defined. Also,
The fourth channel pulse CH24 defines the supply start timing of the sixth waveform portion PS6 generated in the period t24, and the fifth channel pulse CH25 defines the supply start timing of the seventh waveform portion PS7 generated in the period t25.

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 feeding mechanism 12.
It has and.

The carriage mechanism 11 includes a carriage to which the recording head 8 is attached, and a drive motor (for example, D which drives the carriage via a timing belt or the like).
The recording head 8 is moved in the main scanning direction. The paper feed mechanism 12 is composed of 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 described above is a kind of the liquid jet head of 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 case 2
5 and the flow path unit 26 joined to the front end surface of

The case 25 is a block-shaped member made of synthetic resin in which a storage space 27 whose front and rear ends are open is formed. The vibrator unit 24 is stored and fixed in the storage space 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 stacking piezoelectric bodies and internal electrodes, and is a longitudinal-vibration-mode piezoelectric vibrator that can expand and contract in a vertical direction orthogonal to the stacking direction. Is. The tip end surface of each piezoelectric vibrator 21 is joined to the island portion 28 of the flow path unit 26. This piezoelectric vibrator 21 behaves like a capacitor. That is, the potential of the piezoelectric vibrator 21 (vibrator potential) rises due to charging, and the potential falls due to discharging. Then, when the supply of the signal is stopped, the potential of the piezoelectric vibrator 21 is held at the potential immediately before the stop.

In the flow path unit 26, the nozzle plate 30 is arranged on one surface side of the flow path forming substrate 29 with the flow path forming substrate 29 interposed therebetween, and the elastic plate 31 is on the side opposite to the nozzle plate 30. It is configured by arranging and stacking on the other surface side.

A plurality of nozzle plates 30 (for example, 9
Six nozzle openings 32 are formed by a thin metal plate material (for example, a stainless plate) opened along the sub-scanning direction. The flow path forming substrate 29 includes a reservoir 33 (common ink chamber), an ink supply port 34 (a type of liquid supply port),
It is a plate-shaped member in which an ink flow path (a kind of liquid flow path) including a pressure chamber 35 and a nozzle communication port 36 is formed. In this embodiment, the flow path forming substrate 29 is manufactured by etching a silicon wafer. Elastic plate 3
1 is a resin film 38 on a support plate 37 made of stainless steel.
Is a laminated double-layered composite plate material, and the island portion 28 is formed by annularly removing the support plate 37 at a portion corresponding to the pressure chamber 35.

In the recording head 8, a series of ink flow paths from the reservoir 33 to the nozzle openings 32 through the pressure chambers 35 are 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 vibrator longitudinal direction by charging and expands in the vibrator longitudinal direction by discharging. Therefore, 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 expands. Further, when the vibrator potential is lowered by the discharge, the piezoelectric vibrator 21 expands in the return direction and the pressure chamber 35 contracts.

In this way, the pressure chamber 3 is responsive to the vibrator potential.
Since the volume of No. 5 can be controlled, the ink pressure in the pressure chamber 35 can be changed and ink droplets can be ejected from the nozzle openings 32. For example, ink droplets can be ejected by temporarily expanding the pressure chamber 35 of the reference volume and then rapidly contracting it.

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

The recording head 8 is, as shown in FIG.
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 4
5, a control logic 46, a level shifter circuit including a first level shifter 47 and a second level shifter 48,
The piezoelectric vibrator 21 is provided with a switch circuit including the first switch 49 and the second switch 50. And
Each shift register 41, 42, each latch circuit 43, 4
4, each level shifter 47, 48, each switch 49, 5
0 and the piezoelectric vibrator 21 have nozzle openings 32, respectively.
A plurality is provided corresponding to.

The recording head 8 ejects ink droplets based on the recording data (SI) from the printer controller 1. In the present embodiment, 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, so that the upper bit group of the recording data is first set in the second shift register 42. When the high-order bit group of the print data for all the nozzle openings 32 is set in the second shift register 42, the low-order bit group of the print data is subsequently set in the second shift register 42.
With the setting of the lower bit group of the recording data, the upper bit group of the recording data is shifted to shift to the first shift register 4
Set to 1.

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. Then, the latch pulse (LA
When (T1) is input to each of the latch circuits 43 and 44, the first
The latch circuit 43 latches the upper bit group of the recording data, and the second latch circuit 44 latches the lower bit group of the recording data.

The recording data (upper bit group, lower bit group) latched by the latch circuits 43 and 44 are respectively
It is input to the decoder 45. The decoder 45 performs translation based on the high-order bit group and the low-order bit group of the recording data, and selects each of the waveform portions PS1 to PS7 and the adjustment elements P0 and P20 that form the drive signals COM1 and COM2 shown in FIG. Generate the waveform selection data of.

In the present embodiment, the waveform selection data is generated for each drive signal COM1 and COM2. That is, as shown in FIG. 3, the first drive signal COM1 corresponding to the first
The waveform selection data includes the first adjustment factor P0 (period t10),
The first waveform section PS1 (period t11) and the second waveform section P
It is made up of a total of 3 bits of data corresponding to S2 (period t12). The second waveform selection data corresponding to the second drive signal COM2 is the second adjustment element P20.
(Period t20), third waveform portion PS3 (period t21), fourth waveform portion PS4 (period t22), fifth waveform portion PS5 (period t23), sixth waveform portion PS6 (period t24), and
It is composed of a total of 6 bits of data corresponding to the seventh waveform section PS7 (period t25).

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

The decoder 45 has a control logic 4
The timing signal from 6 is also input. The control logic 46 functions as the timing signal generating means together with the control unit 6, and synchronizes with the input of the latch signal (LAT) and the channel signals (CH-A, CH-B) to generate the timing signals (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.
Is the latch pulse (LAT1) and the first drive signal COM
The first timing signal (TYM-A) is generated by the channel pulse for 1 (CH11, CH12), and the second timing is generated by the latch pulse and the channel pulse (CH21-CH25) for the second drive signal COM2. A signal (TYM-B) is generated.

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

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

The first drive signal COM1 from the drive signal generating circuit 9 is supplied to the input side of the first switch 49, and the second drive signal COM to the input side of the second switch 50.
2 is supplied. The piezoelectric vibrator 21 is electrically connected to the output side of each switch 49, 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 a first switch means (a type of switch means of the present invention).

The above waveform selection data is stored in each switch 4
Control the operation of 9,50. That is, during a period in which the waveform selection data input to the first switch 49 is [1], the first switch 49 is in the conductive state and the first drive signal C
The OM1 is supplied to the piezoelectric vibrator 21. Similarly, the second drive signal COM2 is supplied to the piezoelectric vibrator 21 while the waveform selection data input to the second switch 50 is [1]. Then, the supplied drive signals COM1, CO
The vibrator potential of the piezoelectric vibrator 21 changes according to M2.
On the other hand, while the waveform selection data input to the switches 49 and 50 are both [0], the level shifters 47 and 48 are
Does not output an electric signal for operating each of the switches 49 and 50, so that a drive signal is not supplied to the piezoelectric vibrator 21. In short, the waveform selection data is [1]
The adjusting elements P0 and P20 and the waveform portions (first waveform portion PS1 to seventh waveform portion PS7) in the period in which is set are selectively supplied to the piezoelectric vibrator 21.

Thus, in this embodiment, the decoder 4
5, control logic 46, and level shifters 47, 4
Reference numeral 8 functions as the switch control means of the present invention, and controls the switches 49 and 50 according to the recording data (gradation data).

Next, the drive signals COM1 and COM2 generated by the drive signal generation circuit 9 and these drive signals COM.
The supply control of 1 and COM2 to the piezoelectric vibrator 21 will be described.

The drive signal illustrated in FIG. 3 includes the first drive signal COM1 and the second drive signal COM2, as described above. Then, the first drive signal COM1 is in the period t1.
The first adjusting element P0 is generated at 0, the first waveform portion PS1 is generated at the period t11, and the second waveform portion PS2 is generated at the period t12. In addition, the second drive signal COM
2 is the second adjustment factor P20 generated in the period t20,
The third waveform portion PS3 generated in the period t21 and the period t2
The fourth waveform portion PS4 generated in step 2, the fifth waveform portion PS5 generated in period t23, the sixth waveform portion PS6 generated in period t24, and the seventh waveform portion PS7 generated in period t25. Consists of.

First, the first drive signal COM1 will be described.

The first adjusting element P0 is composed of a constant wave element at the intermediate potential Vhm. As will be described later, the first adjusting element P0 is provided for the piezoelectric vibrator 2 to adjust the vibrator potential to the intermediate potential Vhm at the beginning of the recording cycle T.
1 is supplied. The intermediate potential Vhm is a kind of reference potential and is also the start / end potential of each of the drive pulses DP1 to DP3.

The first waveform portion PS1 has a first constant potential element P1.
, The first expansion element P2, and the first expansion hold element P3
A first ejection element P4, a vibration damping hold element P5, an expansion vibration damping 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 sets the potential from the intermediate potential Vhm to the first expansion potential Vh1 at a relatively gentle constant gradient that does not eject ink droplets. The first expansion hold element P3 is a waveform element to be raised and is a constant waveform element at the first expansion potential Vh1. The first ejection element P4 has a first expansion potential Vh.
It is a waveform element that steeply drops the potential from 1 to the contraction potential VL, and the vibration damping hold element P5 is a constant waveform element at the contraction potential VL. The expansion damping element P6 has a contraction potential VL.
To the intermediate potential Vhm, the second constant potential element P7 is a waveform element that raises the potential with a constant gradient that does not eject ink drops, and the second constant potential element P7 is a constant waveform element at the intermediate potential Vhm.

The second waveform section PS2 has a third constant potential element P8.
, The first expansion element P9, and the first expansion hold element P10
, The first ejection element P11, and the damping hold element P12
And an expansion damping element P13. Among these wave elements, the first expansion element P9 and the first expansion hold element P1
0, the first ejection element P11, the damping hold element P12, and the expansion damping element P13 are respectively the first expansion element P2, the first expansion hold element P3, the first ejection element P4, and the vibration hold of the first corrugated portion PS1. Element P5 and expansion damping element P6
Are set to the same potential difference and time width. Also, the third
The constant potential element P8 is a waveform element that is constant at the intermediate potential Vhm like the first constant potential element P1, but the generation time is different.

With this first drive signal COM1, the first expansion element P2 and the first expansion hold element P of the first waveform section PS1 are used.
3, the first ejection element P4, the damping hold element P5, and
The expansion damping element P6 is the first middle dot drive pulse DP1.
Make up. Similarly, the first expansion element P9, the first expansion hold element P10, and the first ejection element P1 of the second corrugated portion PS2.
1, damping hold element P12, and expansion damping element P1
3 constitutes the second middle dot drive pulse DP2. These middle dot drive pulses DP1 and DP2 are a kind of the first drive pulse of the present invention as described above, and are used in the recording gradation with the largest amount of landed ink per unit area, as will be described later. The middle dot drive pulses DP1 and DP2 have the same waveform shape, and when supplied to the piezoelectric vibrator 21, the ink droplets of the amount corresponding to the middle dots are ejected from the nozzle openings 32.

Explaining the first middle dot drive pulse DP1 as an example, the supply of the first expansion element P2 causes the piezoelectric vibrator 21 to contract in the element longitudinal direction, and the pressure chamber 35 to the intermediate potential Vhm (reference potential). It expands from the corresponding reference volume 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 expanded state of the pressure chamber 35 is
It is maintained over the supply period of the first expansion hold element P3.

After that, the first ejection element P4 is supplied and the piezoelectric vibrator 21 expands. Due to the expansion 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 contracted state of the pressure chamber 35 is maintained over the supply period of the vibration damping hold element P5. During this period, the ink pressure in the pressure chamber 35, which has decreased due to the ejection of the ink droplets, rises again due to its natural vibration. The expansion damping element P6 is supplied in accordance with the rising timing. This expansion damping element P6
Supply of the pressure chamber 35 expands and returns to the reference volume,
The pressure fluctuation of the ink in the pressure chamber 35 is absorbed.

Further, in the first drive signal COM1, the middle dot drive pulses are made to come to each other 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. DP1 and DP2 are connected to each other at a start / end potential (intermediate potential Vhm) so that the middle dot drive pulses DP1 and DP2 are generated at constant intervals over the recording cycle 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. is doing.

In this way, each middle dot drive pulse D
If P1 and DP2 are generated at regular intervals across the recording cycle T, the middle dot drive pulses DP1 and D
When P2 is continuously supplied to the piezoelectric vibrator 21, that is, when recording is performed with the recording gradation of the large dot having the largest amount of landed ink per unit area, the meniscus (exposure at the nozzle opening 32) at the start of supply. The free surface of the ink) can be kept constant. As a result, the flight of ink drops can be stabilized and the image quality can be improved. Also, this first
The drive pulse included in the drive signal COM1 is only the middle dot drive pulses DP1 and DP2. Therefore, the generation interval of these middle dot drive pulses DP1 and DP2 can be narrowed within the range in which the recording head 8 (piezoelectric vibrator 21) can respond. By doing so, it is possible to realize high frequency driving of the recording head 8 in the large dot recording gradation and maximize its performance.

Next, the second drive signal COM2 will be described.

The second adjusting element P20 is composed of a constant wave element at the intermediate potential Vhm like the first adjusting element P0. Then, this second adjustment element P20
At the beginning of the recording cycle T, the oscillator potential is set to the intermediate potential V
It is supplied to the piezoelectric vibrator 21 for adjustment to hm.
In this embodiment, at the beginning of the recording cycle T, either the second adjusting element P20 or the first adjusting element P0 is supplied to the piezoelectric vibrator 21. Therefore, 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 has a fourth constant potential element P2.
It is composed of 1. This fourth constant potential element P21
Is a waveform element that is constant at the intermediate potential Vhm.

The fourth waveform section PS4 has a fifth constant potential element P2.
2, a fine vibration first expansion element P23, and a fine vibration constant potential element P24, and functions as a front fine vibration waveform (a kind of fine vibration waveform in the present invention). The fifth constant potential element P22 is a waveform element that is constant at the intermediate potential Vhm and is generated for an extremely short time. Micro-vibration first expansion element P23
Is a waveform element that raises the potential from the intermediate potential Vhm to the slight vibration expansion potential Vh2 with a relatively gentle constant gradient,
The fine vibration constant potential element P24 is a waveform element that is constant at the fine vibration expansion potential Vh2.

The fifth waveform section PS5 includes a front side connection constant potential element P25, a connection element P26, and a rear side connection constant potential element P2.
7 and functions as the connecting waveform element in the present invention. The front-side connection constant potential element P25 is a waveform element that is constant at the slight vibration expansion potential Vh2, and is generated for an extremely short time. The connecting element P26 has a slight vibration expansion potential Vh2.
Is a waveform element that steeply drops the potential from to the intermediate potential Vhm. The rear-side connection constant potential element P27 has an intermediate potential V
It is a constant waveform element at hm and is generated for a very short time. The fifth waveform portion PS5 is a portion for connecting two waveform elements having different end potentials and different start potentials, and is not supplied to the piezoelectric vibrator 21. Therefore, the gradient of the connecting element P26 can be steeply set to the maximum controllable. Thereby, the waveform elements before and after (the fine vibration constant potential element P24, the sixth constant potential element P2 of the sixth corrugated portion PS6).
8) can be generated in a very short time interval.

The sixth waveform section PS6 includes a sixth constant potential element P2.
8, the second expansion element P29, and the second expansion hold element P
30, a second ejection element P31, and a front ejection hold element P32. The sixth constant potential element P28 is a constant waveform element at the intermediate potential Vhm, and is generated for an extremely 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 the second expansion potential Vh.
It is a constant wave element at h3. In addition, the second ejection element P3
Reference numeral 1 is a waveform element that sharply decreases the potential from the second expansion potential Vh3 to the ejection potential Vh4, and the front ejection hold element P32 is a constant waveform element at the ejection potential Vh4. The ejection potential Vh4 in the present embodiment is set to the same potential as the microvibration expansion potential Vh2 in the fourth waveform portion PS4.

The seventh waveform portion PS7 includes a rear ejection hold element P33, a contraction damping element P34, and a seventh constant potential element P.
And 35. The rear ejection hold element P33 is a waveform element that is constant at the ejection potential Vh4 and is generated for an extremely short time. The contraction damping element P34 has a discharge potential Vh4.
From the intermediate potential Vhm to the intermediate potential Vhm with a relatively gentle constant gradient, the seventh constant potential element P35 is a constant waveform element with 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 cycle T.

With this second drive signal COM2, the second expansion element P29 of the sixth waveform portion PS6 and the seventh waveform portion PS7,
Second expansion hold element P30, second ejection element P31, ejection hold elements P32, P33, and contraction damping element P
34 constitutes a small dot drive pulse DP3. This small dot drive pulse DP3 is a kind of the small droplet drive pulse in the present invention, and it is possible to eject a smaller amount of ink droplets than the above-mentioned 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 droplets corresponding to the small dot are ejected from the nozzle openings 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, from the reference volume corresponding to the intermediate potential Vhm to the second expansion volume corresponding to the second expansion potential Vh3. Expands to. Due to this expansion, a relatively strong negative pressure is generated in the pressure chamber 35, and the meniscus is largely drawn to the pressure chamber 35 side. The expansion state of the pressure chamber 35 is determined by the second expansion hold element P3.
It is maintained for a supply period of zero. During this time, the moving direction of the central portion of the meniscus is reversed to the ejection direction, and the central portion rises in a columnar shape.

Then, the second ejection element P31 is supplied and the piezoelectric vibrator 21 expands. The expansion of the piezoelectric vibrator 21 causes the pressure chamber 35 to move from the second expansion volume to the discharge potential Vh.
The discharge volume corresponding to 4 is rapidly contracted. And
Due to the rapid contraction of the pressure chamber 35, the ink in the pressure chamber 35 is pressurized to promote the growth of the columnar portion, and the columnar portion is torn in the middle and ejected as an ink droplet.

After the second ejection element P31, the front ejection hold element P32 and the rear ejection 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 supplement the ink pressure in the pressure chamber 35 that has decreased due to the ejection of ink droplets. That is, by supplying the contraction damping element P34,
The pressure chamber 35 contracts 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 ejection hold element P33, and the contraction of the fourth waveform portion PS4 and the seventh waveform portion PS7 are contracted. The damping element P34 constitutes a slight vibration pulse. When the micro-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, and the meniscus vibrates slightly.

That is, the piezoelectric vibrator 21 is gently contracted in the element longitudinal direction by the supply of the microvibration first expansion element P23. As a result, the pressure chamber 35 relatively slowly expands 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 drawn into the pressure chamber 35 side. The expansion state of the pressure chamber 35 is determined by the rear discharge hold element P33.
Will be maintained until the end of supply. During this time, the meniscus vibrates slightly in the vicinity of the nozzle opening 32 toward the pressure chamber side and the discharge side. Due to this slight vibration of the meniscus, the nozzle opening 32
The thickened ink in the vicinity is dispersed to prevent thickening of the ink. Furthermore, the supply of the contraction damping element P34 causes the pressure chamber 35 to contract to the reference volume. This contraction causes pressure chamber 3
The ink in 5 is slightly pressurized, and the meniscus slightly moves to the ejection side. A slight vibration is continued by the movement of the meniscus.

Then, the waveform elements (P23 to P3) constituting the small dot drive pulse DP3, the front fine vibration waveform (PS4), and the connection waveform element (PS5).
4) is a waveform element (P2 to P6, P2) of which a part of the generation period constitutes the middle dot drive pulses DP1 and DP2.
9 to P13). For example, the generation period of the microvibration first expansion element P23 of the front microvibration waveform PS4 is the first in the first middle dot drive pulse DP1.
It overlaps with the generation period of the expansion hold element P3 and the first ejection element P4. Also, the small dot drive pulse DP
Part of the second expansion element P29 of the third generation period is the first
It overlaps with the generation period of the expansion damping element P6 of the middle dot drive pulse DP1. Further, the generation period of the contraction damping element P34 of the small dot drive pulse DP3 overlaps the generation period of the first expansion element P9 of the second middle dot drive pulse DP2 at the end portion.

In this way, each drive pulse DP1 to DP
3, the waveform elements PS4, PS5 are driven by the respective drive signals COM1, C
If they are separately provided in the OM2 and are generated by overlapping in time, the drive pulses DP1 to DP3 and the micro-vibration pulse can be efficiently arranged even with the recording period T of a limited length.
As a result, high frequency driving of the recording head 8 can be realized.

Further, this small dot drive pulse DP
3 generation timing, the first middle dot drive pulse D
It is set in the middle of P1 and the second middle dot drive pulse DP2. Specifically, small dot drive pulse DP
The generation timing of the second ejection element P31 in No. 3 is the generation timing of the first ejection element P4 in the first middle dot drive pulse DP1 and the generation timing of the second middle dot drive pulse D.
It is set to just the middle of the generation timing of the first ejection element P11 in P2. 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 recording gradation is obtained. The middle dot drive pulse DP2 is supplied to the piezoelectric vibrator 21. Further, in the recording gradation of the small dot, the small dot driving pulse DP3 is supplied to the piezoelectric vibrator 21.

Here, the small dot drive pulse DP3
Is generated in the middle of the first middle dot drive pulse DP1 and the second middle dot drive pulse DP2, even if the recording gradation is switched between the previous recording cycle T and the current recording cycle T, the ink droplet ejection intervals are made uniform. it can. For example, in the case where a small dot is recorded in the previous recording cycle T, a large dot is recorded in the current recording cycle T, a large dot is recorded in the previous recording cycle T, and a small dot is recorded in the current recording cycle T. The discharge interval can be made uniform. As a result, the meniscus state in the current recording cycle T becomes constant, and the ink droplet ejection can be stabilized,
As a result, the image quality can be improved.

Next, the multi-gradation control in this embodiment will be described with reference to FIGS. In this multi-gradation control, the switches 49 and 50 are controlled by the switch control means (decoder 45, control logic 46, and level shifters 47 and 48, and so on). Then, 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 simultaneously supplied to the piezoelectric vibrator 21. This is to stabilize the oscillator potential.

First, the case of non-recording will be described. In this case, the decoder 45 uses the non-recorded gradation data [00].
The first waveform selection data [000] and the second waveform
Waveform selection data [111001] is generated. And
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 the first drive signal COM1 and the second drive signal COM2.
To control the supply to the piezoelectric vibrator 21.

That is, in the period t10 (t20),
The second adjusting element P20 is supplied to the piezoelectric vibrator 21. As a result, the vibrator potential is adjusted to the intermediate potential Vhm. Here, the first adjusting element P0 and the second adjusting element P20 are selected according to the waveform portion (waveform element) to be supplied next, and the selected elements are supplied to the piezoelectric vibrator 21. Specifically, if the waveform portion to be supplied next has the first drive signal COM1, the first adjustment element P0 is selected, and if it has the second drive signal COM2, the second adjustment element P20 is selected. It This is to reduce the number of operations of each switch 49, 50. That is, when the number of operations of each switch 49, 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, in the periods t11 and t12, the first switch 49 is controlled to be in the disconnected state, and the periods t21 and
During the periods t22 and t25, the second switch 50 is controlled to be in the connected state. As a result, the third waveform portion PS3 is supplied to the piezoelectric vibrator 21 during the period t21, the fourth waveform portion PS4 is supplied during the period t22, and the seventh waveform portion PS7 is supplied during the period t25. That is, as indicated by the thick line in FIG. 4, the microvibration pulse (P23, P24, P33, P34) is supplied to the piezoelectric vibrator 21. As a result, the thickened ink near the nozzle openings 32 is dispersed and the thickening of the ink is prevented.

In this embodiment, the slight vibration expansion potential V
By aligning h2 and the ejection potential Vh4 to the same potential,
Part of the waveform elements (P33, P34) forming the small dot drive pulse DP3 are part of the microvibration pulse, that is,
It is used as the rear micro-vibration waveform. In addition, the micro-vibration waveform PS4 is converted to the second drive signal CO by using the connection waveform element PS5.
It is incorporated in M2. As a result, the small dot drive pulse DP3 and the micro-vibration pulse (P23, P24, P33, P34) can be efficiently incorporated within the limited recording period T.

Next, a case of recording a small dot will be described. In this case, the decoder 45 translates the grayscale data [01] of the small dot to obtain the first waveform selection data [000] and the second waveform selection data [11001].
1] is generated. 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 adjusting element P20 is supplied to the piezoelectric vibrator 21, and the vibrator potential is adjusted to the intermediate potential Vhm. Then, the period t11,
The first switch 49 is controlled to be in the disconnected state during the period t12, and the second switch 50 is controlled to be in the connected state during the periods t21, t24, and t25. This allows
As indicated by the thick line in FIG. 5, during the period t21, the third waveform portion PS
3, the sixth waveform portion PS6 is supplied to the piezoelectric vibrator 21 during the period t24, and the seventh waveform portion PS7 is supplied to the piezoelectric vibrator 21 during 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 droplets due to the small dot drive pulse DP3 is generated in the nozzle opening 32.
Is discharged from.

Next, the case of recording middle dots will be described. In this case, the decoder 45 translates the grayscale data [10] of the middle dots to obtain the first waveform selection data [001] and the second waveform selection data [110000].
To generate. 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 adjusting element P20 is supplied to the piezoelectric vibrator 21, and the vibrator potential is adjusted to the intermediate potential Vhm. The first switch 49 is turned off during the period t11, and the second switch 49 is disconnected during the period t21.
The switch 50 is brought into the connected state. As a result, the third waveform portion PS3 of the second drive signal COM2 is supplied to the piezoelectric vibrator 21 as indicated by the thick line in FIG.
21 keeps the vibrator potential at the intermediate potential Vhm.

During the subsequent period t22 to t24, the second switch 50 is controlled to be in the disconnection state, so that the first drive signal COM1 is also supplied to the piezoelectric vibrator 21 from the start of t22 to immediately before the start of t12. The drive signal COM2 is also not supplied. As a result, as indicated by the thin line in FIG. 6, the oscillator potential maintains the intermediate potential Vhm which is the potential immediately before the disconnection. 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 the connected state. As a result, as indicated by the thick line in FIG. 6, the second waveform portion P of the first drive signal COM1
S2 is supplied to the piezoelectric vibrator 21, and a small amount of ink droplet corresponding to the middle dot is ejected by the supply of the second middle dot drive pulse DP2.

As described above, in this embodiment, in the case of the recording gradation of the middle dots, some of the waveform elements (the third constant potential element P8, the first expansion element P9, First expansion hold element P10, first discharge element P
11, damping hold element P12, expansion damping element P13)
And a part of the waveform elements (fourth constant potential element P21) forming the second drive signal COM2 are combined and supplied to the piezoelectric vibrator 21. That is, the oscillator potential is maintained at the intermediate potential Vhm by supplying the fourth constant potential element P21 of the second drive signal COM2 during the period (period t11) in which the first drive signal COM1 cannot be supplied due to the waveform elements. 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 in 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 force of the piezoelectric vibrator 21 is decreased. There is a risk. Then, when the holding capacity of the electric charges decreases, the oscillator potential gradually decreases due to the discharge in the non-supply period. For this reason, when the non-supply period is long, the falling width of the vibrator potential becomes large, and when the drive signal is supplied next time, the potential difference between the drive signal potential and the vibrator potential becomes large. In this case, the piezoelectric vibrator 2
The sudden deformation of 1 occurs, and the ink droplet is erroneously ejected. Then, as in the present embodiment, the drive signal COM
If the non-supply period of 1 and COM2 is shortened as much as possible, the fall width of the oscillator potential can be reduced even if the charge retention ability is reduced, so that the drive signals COM1 and COM2.
Can be supplied without hindrance.

Next, the case of recording large dots will be described. In this case, the decoder 45 translates the large dot gradation data [11] to obtain the first waveform selection data [111] and the second waveform selection data [000000].
To generate. 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 adjusting element P0 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 in the connected state in the periods t11 and t12, while the second switch 5 is controlled in the periods t21 to t25.
0 is controlled to the disconnected state. As a result, the first waveform portion PS1 is supplied to the piezoelectric vibrator 21 during the period t11, and the second waveform portion PS2 is supplied during the period t12. That is, as indicated by the thick line in FIG. 7, the first middle dot drive pulse DP1 and the second middle dot drive pulse DP2 are the piezoelectric vibrator 21.
Is supplied to. As a result, a small amount of ink droplets due to the middle dot drive pulse are ejected from the nozzle opening 32 twice in succession, 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 recording gradation of the large dot having the largest ink amount per unit area. That is, the drive pulse (small dot drive pulse DP3 or micro-vibration pulse) used only for other recording gradations is included in the other drive signal COM2. Therefore, the generation intervals of these middle dot drive pulses DP1 and DP2 can be set freely without being restricted by other drive pulses. As a result, the middle dot drive pulses DP1, DP
The generation interval of 2 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 sufficiently exhibited.

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 in, 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 other recording gradations are not used for solid recording, and the drive frequency of the recording head 8 at other recording gradations can be set lower than the drive frequency at the time of large dot recording.

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

Further, the middle dot drive pulses DP1 and D
The generation period of P2 and the generation period of other drive pulses are
Since they are superposed at least in part, the recording cycle T can be set shorter than when a plurality of drive pulses are connected in series. 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.

Further, since the second drive signal includes the composite pulse in which the small dot drive pulse DP3 and the front fine vibration waveform PS4 are connected by the connection waveform element PS5,
It is possible to efficiently incorporate a plurality of types of drive pulses into the second drive signal COM2.

Further, since a part of the waveform elements forming the first drive signal COM1 and a part of the waveform elements forming the second drive signal COM2 are combined and supplied to the piezoelectric vibrator 21, each drive is performed. It is possible to drive with a new pattern that is not specified in the signal. For example, the piezoelectric vibrator 21
The non-supply period of the drive signal to the drive circuit can be shortened as much as possible. This makes it possible to realize complicated control while driving the recording head 8 at a high frequency.

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

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

The illustrated changeover switch 61 functions as a second switch means (a type of switch means of the present invention),
It is provided for each piezoelectric vibrator 21. This changeover switch 6
Reference numeral 1 denotes a first input contact 61a, a second input contact 61b, and an off contact 61c provided corresponding to the type of drive signal generated, and an output terminal 61d electrically connected to the piezoelectric vibrator 21.
And one of the contacts 61a to 61c is selectively electrically connected to the output terminal 61d. And the first
The supply line of the first drive signal COM1 is electrically connected to the input contact 61a, the supply line of the second drive signal COM2 is electrically connected to the second input contact 61b, and the off contact 61c.
Are electrically disconnected.

In this changeover switch 61, the output terminal 61
By switching the contacts 61a to 61c that conduct to d,
The piezoelectric vibrators 2 selectively select the drive signals COM1 and COM2.
1 can be supplied. That is, the first drive signal COM1 can be supplied by connecting the first input contact 61a to the output terminal 61d, and the second drive signal COM2 can be supplied by connecting the second input contact 61b to the output terminal 61d. When the OFF contact 61c is electrically connected to the output terminal 61d, the first drive signal C
Neither OM1 nor the second drive signal COM2 is supplied.

The operation of the changeover switch 61 is controlled by the decoder 62 and the 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 by translating the recording data (gradation data), the first input contact 61a ([1]) and the second input contact 61b.
Switch switching data indicating either ([2]) or the off contact 61c ([0]) is generated. Then, the switch switching data is output to the switch control circuit 63 in synchronization with the timing from the control logic 46 '. As a result, 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, two middle dot drive pulses D within one recording cycle T.
Although the first drive signal COM1 having P1 and DP2 is illustrated, the configuration is not limited to this. For example, the first drive signal C
OM1 may be a signal having one large dot drive pulse within one recording cycle T, that is, a drive pulse capable of ejecting an ink droplet of an amount corresponding to a large dot. In this case, the second drive signal COM2 includes, for example, a composite pulse (a kind of the second drive pulse of the present invention) including a middle dot drive pulse, a small dot drive pulse, and a fine vibration pulse. Further, three or more normal dot drive pulses, that is, a drive pulse capable of ejecting the ink amount of a small dot by one may be included. In this case, the second drive signal COM2 includes, for example, a micro-vibration pulse (a kind of the second drive pulse of the present invention).

Further, in the above-mentioned embodiment, two kinds of drive signals COM1 and COM2 are illustrated, but the same operation can be performed by generating three or more kinds of drive signals. For example, a dedicated drive signal may be generated for each recording gradation, and a total of four types of drive signals may be generated. In this case, one type of drive signal used in the large dot recording gradation is the first drive signal of the present invention,
Three types of drive signals used for other recording gradations are the second drive signals of the present invention.

Further, regarding the pressure generating element, in the above embodiment, the case where the so-called longitudinal vibration mode piezoelectric vibrator 21 is used has been described, but the present invention is not limited to this.
That is, various elements can be used as long as the potential is changed by the supply of the drive pulse and the potential immediately before is held when the supply of the drive pulse is interrupted. For example, a so-called flexural vibration mode piezoelectric vibrator may be used, or an electrostatic actuator may be used.

The present invention is not limited to printers, but can be applied to various ink jet recording apparatuses such as plotters, facsimile machines, and copying machines. The present invention can also be applied to liquid ejecting apparatuses other than recording apparatuses. For example, a display manufacturing apparatus that manufactures a color filter such as a liquid crystal display, an organic EL (Electro Lu
electrode manufacturing equipment for forming electrodes such as minescence) display and FED (surface emitting display), chip manufacturing equipment for manufacturing biochips (biochemical elements), and micropipettes that supply an extremely small amount of sample solution in an accurate amount Can be applied. Then, in the display manufacturing apparatus, from the color material ejecting head to R (Red), G (Green), and B
Discharge the solution of each color material of (Blue). Further, in the electrode manufacturing apparatus, a liquid electrode material is ejected from the electrode material ejecting head. In the chip manufacturing apparatus, a bio-organic substance solution is ejected from the bio-organic substance ejecting head.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an inkjet printer.

FIG. 2 is a cross-sectional view illustrating a configuration of a recording head in a vertical vibration mode.

FIG. 3 is a diagram illustrating drive signals generated by a drive signal generation circuit and supply control of the drive signals.

FIG. 4 is a diagram illustrating supply control of drive signals during non-recording.

FIG. 5 is a diagram illustrating drive signal supply control during small dot recording.

FIG. 6 is a diagram illustrating supply control of drive signals during middle-dot recording.

FIG. 7 is a diagram illustrating drive signal supply control during large dot recording.

FIG. 8 is a block diagram illustrating another example of the switch means.

[Explanation of symbols]

1 ... Printer controller, 2 ... Print engine, 3
... external I / F, 4 ... RAM, 5 ... ROM, 6 ... control unit,
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 ... Transducer unit, 25 ...
Case, 26 ... Flow path unit, 27 ... Storage space, 28 ...
Island part, 29 ... Flow path forming substrate, 30 ... Nozzle plate, 3
1 ... Vibration 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, 4
6, 46 '... Control logic, 47 ... First level shifter,
48 ... Second level shifter, 49 ... First switch, 50 ...
Second switch, 61 ... Changeover switch, 62 ... Decoder,
63 ... Switch control circuit

Continued front page    F-term (reference) 2C057 AF07 AF39 AG44 AG47 AM15                       AM16 AR08 AR16 BA04 BA14                       CA01

Claims (7)

[Claims] 1. A liquid ejecting head having a pressure generating element capable of causing a pressure fluctuation in the liquid in the pressure chamber and a nozzle opening communicating with the pressure chamber, and a drive for repeatedly generating a drive signal including a drive pulse for each ejection cycle. A signal generating means, a switch means capable of controlling the supply of the drive signal to the pressure generating element, and a switch control means for controlling the operation of the switch means are provided. In the liquid ejecting apparatus capable of controlling the supply of liquid droplets and controlling the discharge of liquid droplets from the nozzle openings, the drive signal generating unit is a first drive pulse used in a landing gradation with the largest amount of landing liquid per unit area. Generating a first drive signal having a first drive pulse at even intervals, and a series of second drive signals having a second drive pulse used for another landing gradation, At least a part of the generation period of one drive pulse and the generation period of the second drive pulse are overlapped with each other, and the switch control means is configured to selectively supply each drive signal to the pressure generating element. Liquid ejector. 2. The liquid ejecting apparatus according to claim 1, wherein a plurality of the first drive pulses are generated within one ejection cycle. 3. The liquid ejecting apparatus according to claim 1, wherein the second drive pulse is a small droplet drive pulse having a smaller amount of ejected liquid than the first drive pulse. 4. The second drive pulse comprises a small droplet drive pulse having a smaller amount of ejected liquid than the first drive pulse, and a micro-vibration waveform for varying the volume of the pressure chamber to the extent that droplets are not ejected. A composite pulse connected by a connection waveform element that is not supplied to the pressure generating element, wherein the switch control means supplies a minute vibration waveform and a part of the second drive pulse to the pressure generating element in a non-ejection landing gradation, The liquid ejecting apparatus according to claim 1, wherein the meniscus is slightly vibrated. 5. The small droplet drive pulse is applied to the adjacent first droplets.
The liquid ejecting apparatus according to claim 3 or 4, wherein the liquid ejecting apparatus is generated in the middle of the drive pulses. 6. The first drive pulse is a micro-vibration pulse that causes the meniscus to vibrate by applying a pressure fluctuation to the liquid in the pressure chamber to the extent that a droplet is not ejected. Item 3. The liquid ejecting apparatus according to item 2. 7. The second drive signal includes a constant potential element that is constant at a starting potential of the first drive pulse, and the switch control means generates pressure in the constant potential element during a non-supply period of the first drive pulse. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus supplies the liquid to an element.