JP2003072063A - Inkjet printer, and device and method for driving its head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for driving a head in an inkjet printer wherein a driving voltage to piezoelectric elements in each nozzle array can be set to be an optimum driving voltage of each nozzle array by maintaining a reproducibility of a waveform of a driving signal in a simple structure. SOLUTION: This head driving device 100 of the inkjet printer has the piezoelectric elements corresponding to the plurality of nozzle arrays. The head driving device 100 is so constituted that a driving signal supplying circuit 112 comprises one waveform generating circuit 80, amplifiers 122A-122N for amplifying the output signal from the waveform generating circuit 80 by each nozzle array, and voltage adjusting circuits 121A-121N for adjusting each input signal to be input to each amplifier.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention drives a piezoelectric element provided corresponding to a nozzle of each color for ejecting ink droplets of each color based on one drive waveform in an ink jet printer head. The present invention relates to a head drive technology for an inkjet printer.

[0002]

2. Description of the Related Art Conventionally, as an output device of a computer, an ink jet type color printer of a type that ejects ink of several colors from a recording head has been widely used, and an image processed by a computer or the like is printed in multiple colors and multiple gradations. It is widely used to

For example, in an ink jet printer using a piezoelectric element as a driving element for ejecting ink, a plurality of piezoelectric elements provided corresponding to a plurality of nozzle rows of a print head are selectively driven. Thus, the ink droplets are ejected from the nozzles based on the dynamic pressure of each piezoelectric element, and the ink droplets are attached to the printing paper to form dots on the printing paper, thereby performing printing.

Here, each piezoelectric element is provided corresponding to a nozzle for ejecting an ink droplet, and is driven by a drive signal supplied from a driver IC (head drive circuit) mounted in the print head. The ink droplets are ejected.

[0005]

By the way, in a relatively low-priced ink jet printer, in order to reduce the cost, the piezoelectric elements corresponding to the nozzle rows of each color are driven based on one drive waveform. It is configured.

On the other hand, the nozzle rows of each color are different due to variations in nozzle shape, characteristics of piezoelectric elements, etc.
The ejection amount of the ink droplet with respect to the driving voltage of the piezoelectric element varies.

Therefore, in order to correct the ink droplet ejection amount of each nozzle row at the time of assembly of each ink jet printer, for each nozzle row, a predetermined ink droplet ejection amount is set. Information about the measured drive voltage (drive voltage information) is held in the control unit of the printer body.

When the ink jet printer is turned on or when printing is started, the driving voltage information of each nozzle row is read, and the average value of the optimum driving voltage for each nozzle row is used to correspond to each nozzle row. The piezoelectric element is drive-controlled. As a result, the ink droplet ejection amounts of the nozzle rows of each color are averaged, and the color print quality is improved.

However, when the piezoelectric element corresponding to each nozzle row is driven and controlled by the average value of the optimum driving voltage of each nozzle row, the actual driving voltage deviates from the optimum driving voltage of each nozzle row. However, the color tones are slightly different, and for example, each inkjet printer may have a reddish tone or a bluish tone.

On the other hand, for example, the drive signal from the drive signal supply circuit is distributed to each nozzle array, amplified by each amplifier, and applied to the piezoelectric element of each nozzle array, so that each nozzle array can It is also possible to set the drive signal to the optimum drive voltage for each nozzle row by adjusting the amplification factor of the amplifier.

By the way, in such a structure, the drive signals applied to the piezoelectric elements of the respective nozzle rows are amplified by the respective amplifiers with different amplification factors. For example, when the optimum drive voltage of the nozzle row for black printing is 20V and the optimum drive voltage of the nozzle row for magenta printing is 18V, the drive voltage of the drive signal is 0.6V.
If it is 6V, the amplification factor of the amplifier is 30 times and 27, respectively.
By doubling the setting, desired optimum drive voltages 20V and 18V can be obtained, respectively.

However, when each amplifier is adjusted to have such a different amplification factor, distortions such as overshoot and undershoot of the drive signal itself are also amplified with different amplification factors. For this reason, the reproducibility of the waveform of the drive signal is different between the nozzle rows, and the colors are also slightly different.

Therefore, an object of the present invention is to set the drive voltage for the piezoelectric element of each nozzle row to the optimum drive voltage for each nozzle row while maintaining the reproducibility of the waveform of the drive signal with a simple configuration. An object of the present invention is to provide a head driving device and a head driving method for an inkjet printer.

[0014]

In order to solve the above problems, in the present invention, an amplifier is provided for each nozzle row in the drive signal supply circuit, and the input voltage of these amplifiers is set for each nozzle row. By performing the adjustment, the piezoelectric elements corresponding to the respective nozzle rows are drive-controlled with the optimum drive voltage, and the inter-row correction is performed.

That is, in the head driving device of the ink jet printer according to the first aspect of the invention, the piezoelectric element that applies pressure to the ink provided corresponding to each of the plurality of nozzle rows is selectively driven at a predetermined printing timing. A head drive device for an inkjet printer, which is driven by one drive signal from a supply circuit and ejects ink droplets from a corresponding nozzle row to perform recording, wherein the drive signal supply circuit includes one waveform generation circuit. An amplifier that amplifies the output signal from the waveform generation circuit for each nozzle row, and a voltage adjusting circuit that adjusts the voltage of the input signal to each amplifier are further included.

According to a seventh aspect of the present invention, there is provided a method of driving a head of an ink jet printer in which a piezoelectric element that applies pressure to ink provided corresponding to each of a plurality of nozzle rows is selectively driven at a predetermined printing timing. A method of driving a head of an inkjet printer, which is driven by one drive signal from a supply circuit and ejects ink droplets from a corresponding nozzle row to perform recording, wherein one waveform generation circuit and a waveform generation circuit A drive signal supply circuit equipped with an amplifier that amplifies the output signal for each nozzle row, and the voltage of the input signal to each amplifier is adjusted by a voltage adjustment circuit and applied to the piezoelectric element of each nozzle row. It is characterized in that the drive signal to be adjusted is adjusted to an optimum drive voltage for the piezoelectric element of each nozzle row.

According to this structure, the drive signal for the piezoelectric element of each nozzle row is set to the optimum drive voltage for the piezoelectric element of each nozzle row by the voltage adjusting circuit in the drive signal supply circuit. As a result, as compared with the conventional case where the piezoelectric element of each nozzle row is driven and controlled by the average value of the optimum drive voltage for the piezoelectric element of the nozzle row of each color for color printing, each nozzle row is controlled. The drive voltage of the drive signal applied to the piezoelectric element is set to the optimum drive voltage.

Further, in the ink jet printer head drive device according to the present invention, the gains of all the amplifiers are made constant. Further, in the ink jet printer head driving method according to an eighth aspect of the present invention, the gains of all the amplifiers are constant.

According to this structure, since the amplification factors of the amplifiers corresponding to the respective nozzle rows are the same, the reproducibility of the waveform including the overshoot and undershoot of the drive signal is the same between the nozzle rows. . Therefore, the color of each nozzle row does not delicately differ from each other, and the print quality of color printing is improved.

According to another aspect of the head drive device of the present invention, the voltage adjusting circuit includes a first resistor connected in series between the waveform generating circuit and each amplifier, and the connection between the first resistor and each amplifier. And a second resistor connected between the point and the ground, respectively.

According to a ninth aspect of the present invention, in the head driving method, the voltage adjusting circuit includes a first resistor connected in series between the waveform generating circuit and each amplifier, and a connection between the first resistor and each amplifier. And a second resistor connected between the point and the ground, respectively.

According to this structure, since the voltage adjusting circuit corresponding to each nozzle row is composed of the first resistance and the second resistance, respectively, the first resistance and the second resistance can be formed with a simple structure. The voltage can be easily adjusted by the voltage dividing ratio of the resistance.

According to a fourth aspect of the present invention, there is provided the head drive device in which the first resistance is a fixed resistance and each of the second resistances is a variable resistance. The head driving method according to claim 10 is characterized in that the first resistance is a fixed resistance and each of the second resistances is a variable resistance.

According to this structure, the first resistance is the fixed resistance and the second resistance is the variable resistance among the first resistance and the second resistance which are the voltage dividing resistances forming the voltage adjusting circuit. Therefore, by changing the resistance value of the second resistor, it is possible to easily change the voltage division ratio and adjust the voltage of the drive signal input to the amplifier.

In the head drive device according to the present invention, the drive signal supply circuit is composed of an IC, and each of the second resistors is provided outside the IC which constitutes the drive signal supply circuit. It is characterized by 12. The head driving method according to claim 11, wherein the drive signal supply circuit is composed of an IC, and each of the second resistors forms a drive signal supply circuit.
It is characterized in that it is provided outside C.

According to this structure, since the second resistor of the voltage adjusting circuit for adjusting the drive voltage is provided outside the IC constituting the drive signal supply circuit, the second resistor is a fixed resistor. However, the drive voltage of the drive signal can be easily adjusted to the optimum drive voltage by externally attaching the second resistor having the resistance value that gives the optimum drive voltage to the IC forming the drive signal supply circuit. it can.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. Since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are attached, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these modes.

FIG. 1 is a functional block diagram showing the overall construction of an ink jet printer using the head drive device of the present invention. In FIG. 1, the inkjet printer according to the present embodiment includes a printer body 2 and a carriage mechanism 1.
2, a paper feed mechanism 11 and a print head 10. The paper feed mechanism 11 is composed of a paper feed motor (not shown), a paper feed roller (not shown), and the like, and sequentially feeds a recording medium (not shown) such as printing paper to perform sub-scanning. The carriage mechanism 12 includes a carriage (not shown) on which the print head 10 is mounted and a carriage motor (not shown) that moves the carriage via a timing belt (not shown). It is to scan.

The printer main body 2 stores various data such as an interface 3 for receiving print data including multi-valued hierarchical information from a host computer (not shown) and the like and print data including multi-valued hierarchical information. RAM4
A ROM 5 storing routines for performing various data processing, a control unit 6 including a CPU, an oscillation circuit 7, and print data SI expanded into dot pattern data to the print head 10. It has an interface 9 that carries out the functions.

The print head 10 is circuit-connected to the printer body 2 via a flexible flat cable (not shown). As shown in FIG. 1, in the inkjet printer of this embodiment, a drive waveform generation circuit 80 and a drive waveform generation circuit 8 are provided in the printer body 2.
Each of the voltage adjusting circuits 121A to 121N connected to 0,
It has voltage amplifiers (amplifiers) 122A to 122N and current amplifier circuits 113A to 113N.

Print data including multi-valued hierarchical information sent from a host computer or the like is held in a reception buffer 4A inside the printer via the interface 3. The recording data held in the reception buffer 4A is subjected to command analysis, and the control unit 6 executes a process of adding a print position of each character, a type of decoration, a size, a font address, and the like. Next, the control unit 6 expands the analyzed data as print image data in the output buffer 4C and stores it. The RAM 4 is also provided with a work memory (work area) 4B for temporarily storing various work data and the like.

When the print image data corresponding to one scan of the print head 10 is obtained, the print image data is transferred via the interface 9 to the print head 1.
Serially transferred to 0. The print head 10 has a large number of nozzle openings, such as 96 nozzles, in the sub-scanning direction, and ejects ink droplets from each nozzle opening at a predetermined timing. The print head 10 includes a head drive circuit 18 including a shift register 13, a latch circuit 14, a level shifter 15 and a plurality of analog switches 114a.
Is configured. The print data expanded into printing image data on the printer body 2 side is serially transferred from the interface 9 to the shift register 13 in synchronization with the clock signal (CLK) from the oscillation circuit 7. This serially transferred print data (SI / print data)
Are once latched by the latch circuit 14. The latched print data SI is boosted to a voltage capable of driving each analog switch 114a, for example, a predetermined voltage of several tens of volts by the level shifter 15 which is a voltage amplifier. Print data S boosted to a predetermined voltage
I is given to the analog switch 114a.

As shown in FIG. 1, the voltage waveforms are generated by a drive waveform generation circuit (head driver IC) 80 formed on the printer main body 2 side, and the voltage amplifiers 122A to 122N are passed through the voltage adjustment circuits 121A to 121N. Voltage amplification by each of the current amplification circuits 113A to 113A
The current is amplified by 3N and output to the print head 10 mounted on the carriage. On the print head 10 side, a plurality of piezoelectric elements 111 that eject ink droplets from nozzle openings by pressurizing ink in the pressure generating chamber,
And a plurality of piezoelectric elements 111 based on the print data SI
The head drive circuit 18 is configured to select which of the two is to be driven through the analog switch 114a or the like. The head drive circuit 18 causes the analog switch 114a to operate.
The drive signal COM is applied to the piezoelectric element 111 whose is turned on. As a result, the piezoelectric element 111 pressurizes the ink in the corresponding pressure generating chamber and ejects it as an ink droplet from the nozzle opening.

As shown in FIG. 2, the drive waveform generation circuit 80 stores the drive waveform data read from the memory 81 and the memory 81 for storing the drive waveform data provided from the control unit 6 in the printer body 2. A first latch 82 that is temporarily held, an adder 83 that adds an output of the first latch 82 and an output of a second latch 84 described later, and a second latch 84.
And a D / A converter 86 for converting the output of the second latch 84 into analog data. Here, the memory 81 stores predetermined parameters that determine the waveform of the drive signal. As will be described later, the drive signal C
The OM waveform is determined in advance by the predetermined parameters received from the control unit 6 and the like. The drive waveform signals voltage-amplified by the voltage amplifiers (amplifiers) 122A to 122N are current-amplified by the current amplification circuits 113A to 113N described above to the extent that the analog switch 114a can be driven and output.

As shown in FIG. 1, each current amplifier circuit 113
The output sides of A to 113N are connected to the plurality of analog switches 114a of the head drive circuit 18, and each analog switch 114a is connected to the corresponding piezoelectric element 111. Then, on the ejection surface of the print head, N rows, for example, C (cyan), M (magenta), Y (yellow),
There are formed a plurality of nozzles (for example, 96 nozzles in one row) positioned and arranged in six rows corresponding to the six colors of K (black), LC (light cyan), and LM (light magenta). By vibrating the piezoelectric element 111 provided corresponding to each of the plurality of nozzles, the ink in the pressure generating chamber is pressurized to eject an ink droplet from each of the plurality of nozzles.

FIG. 3 shows the configuration of the first embodiment of the head drive device according to the present invention. In FIG. 3, a head drive device 100 is provided with piezoelectric elements 111A and 111A provided corresponding to n (n = N = 6 in this embodiment) nozzle rows of an inkjet printer.
B, ..., 111N, and the piezoelectric elements 111A to 11N
A drive signal supply circuit 112 for supplying a drive signal to one electrode 111a of 1N, and current amplifier circuits 113A and 113B provided between the drive signal supply circuit 112 and the piezoelectric elements 111A to 111N, respectively.・ ・
., 113N and switch circuits 114A, 114B ,.
.., 114N.

Here, in FIG. 3, the piezoelectric element 111 is used.
A to 111N are actually heads of ink jet printers, each of which is provided with one nozzle array for each color, and each nozzle array is provided with a piezoelectric element.

Then, each piezoelectric element 111A to 111N
To the drive signal CO from the drive signal supply circuit 112.
M is actually output sequentially via the switch circuits 114A to 114N controlled by a shift register or the like.

Each of the piezoelectric elements 111A to 111N is, for example, a piezo element, and both electrodes 111a and 111b are provided.
It is configured to be displaced by a voltage applied between them.

Then, each piezoelectric element 111A to 111N
Is configured to eject ink droplets from this nozzle row by applying pressure to the ink in the corresponding nozzle row when discharging based on the drive signal COM from the drive signal supply circuit 112.

The drive signal supply circuit 112 is a driver IC
Is configured to generate a drive signal COM for the head of the inkjet printer, and is arranged in the printer body 2 in the present embodiment.

Each of the current amplifier circuits 113A to 113N has
For example, as shown in FIG. 4, two transistors 115,
It is composed of 116. Of these, the collector of the first transistor 115 is connected to the constant voltage power source V0,
The base is connected to the output of the drive signal supply circuit 112, and the emitter is one electrode 111a of the piezoelectric element 111A to 111N via the switches 114A to 114N.
It is connected to the. As a result, the drive signal supply circuit 11
It conducts on the basis of the signal from 2 and supplies a constant voltage to each piezoelectric element 111A to 111N.

The emitter of the second transistor 116 is connected to one of the electrodes 111a of the piezoelectric elements 111A to 111N via the switches 114A to 114N, and its base is connected to the output of the drive signal supply circuit 112. The collector is via the ground and the piezoelectric element 111
Is connected to the other electrode 111b. This allows
It conducts on the basis of a signal from the drive signal supply circuit 112 to discharge each of the piezoelectric elements 111A to 111N.

The switch circuits 114A to 114N receive the control signals, so that the corresponding piezoelectric elements 11 are received.
It is turned on at a drive timing of 1A to 111N and outputs a drive signal COM to each of the piezoelectric elements 111A to 111N. The switch circuits 114A to 11
4N is actually configured as a so-called transmission gate for turning on / off each of the piezoelectric elements 111A to 114N.

Here, the drive signal supply circuit 112 is
As shown in FIG. 3, one waveform generation circuit 80 and voltage adjustment circuits 121A, 121B, ...
1N and amplifiers 122A, 122B, ...
., 122N. The waveform generation circuit 80
Is a drive signal C based on the input print data.
OM (voltage Vout) is generated. Each of the voltage adjusting circuits 121A to 121N has a first resistor R0 whose one end is connected to the output of the waveform generating circuit 80, and a second resistor RA connected between the other end of the first resistor R0 and the ground. RB, ..., RN.

Here, the first resistor R0 is a fixed resistor, and the second resistors RA, RB, ..., RN are variable resistors. Thereby, the first resistor R0 and the second resistor R0
Each of A to RN constitutes a voltage dividing resistor, and outputs the divided voltage VA to VN from the connection point of the first resistor R0 and the second resistor RA to RN.

At this time, the divided voltages VA to VN are expressed by the formula Vn = VoutRn / (R0 + Rn) where n
= A, B, ..., N, and by appropriately adjusting the resistance values of the second resistors RA to RN, the divided voltages VA to VN to be output can be adjusted.

The amplifiers 122A to 122N are logic amplifiers provided on the IC forming the drive signal supply circuit 112, and the divided voltages VA to VN from the voltage adjusting circuits 121A to 121B are input to their non-inverting inputs, respectively. The current amplification circuit 1 is applied to the inverting input as well as being applied.
The output voltage of 13A to 113N is divided by the voltage dividing resistors R1 and R2 and applied. The amplifiers 122A to 122N are all set to have the same constant gain. That is, they are set to have the same amplification factor.

Head drive device 10 according to an embodiment of the present invention
0 is configured as described above and operates as follows. First, the voltage adjustment of the voltage adjustment circuits 121A to 121N for obtaining the optimum drive voltage for each nozzle row will be described.

Each of the piezoelectric elements 111A to 111N has an optimum driving voltage for ejecting a predetermined amount of ink droplets due to individual differences in characteristic variations and variations in nozzle shape and accuracy.

Therefore, each of the voltage adjusting circuits 121A to 121
1N, the piezoelectric element 1 of the corresponding nozzle row
Current amplifier circuit 1 for each of 11A to 111N
The resistance values of the second resistors RA to RN are set so as to provide the optimum drive voltage via 13A to 113N.

For example, if the optimum driving voltage of the nozzle row for black printing is 20V and the optimum driving voltage of the nozzle row for magenta printing is 18V, the driving voltage of the driving signal for the nozzle row for black printing is given. Is 0.66 V, and the drive voltage of the drive signal of the nozzle array for magenta printing is 0.6
If V is set to V, the amplification factors of the amplifiers are both set to 30 times so that the desired optimum drive voltage 20
V, 18V will be obtained. In this way, the voltage adjustment in each of the voltage adjusting circuits 121A to 121N is completed.

Next, the printing operation of the head driving device 100 will be described. When the drive signal is output based on the data input to the waveform generation circuit 80 of the drive signal supply circuit 112, the amplifiers 122A to 12A corresponding to the nozzle rows are output.
Each of the 2N non-inverting input terminals has a voltage adjusting circuit 12
The divided voltages VA to VN divided by 1A to 121N are input.

The drive signals for the respective nozzle rows, which have been amplified by the amplifiers 122A to 122N at a predetermined amplification rate, are output from the drive signal supply circuit 112 and then amplified by the current amplification circuits 113A to 113N, respectively. By doing so, it becomes the optimum drive voltage for each nozzle row,
The voltage is applied to the piezoelectric elements 111A to 111N via the switch circuits 114A to 114N.

Therefore, the piezoelectric element 1 corresponding to each nozzle row
The voltage adjusting circuit 121 is provided in each of 11A to 111N.
A divided voltage V appropriately adjusted by A to 121N
Since the optimum drive voltage is applied based on A to VN, the piezoelectric elements 111A to 111N are driven, and a predetermined amount of ink droplet is ejected.

In this way, according to the head drive device 100, each amplifier 122A in the drive signal supply circuit 112 is provided.
To 122N and current amplifier circuits 113A to 113N
The amplification factors of the amplifier 1 and the amplifier 1 are set to be the same.
Voltage adjusting circuit 1 provided in the preceding stage of 22A to 122N
By appropriately adjusting the resistance values of the second resistances RA to RN of 21A to 121N, the optimum drive voltage is applied to the piezoelectric elements 111A to 111N corresponding to each nozzle row, and each of the nozzle rows is subjected to the optimum driving voltage. It is possible to eject a predetermined amount of ink droplets.

Therefore, as N nozzle rows, for example,
By performing color printing with 6 nozzle rows corresponding to 6 colors, it is possible to optimize the ink droplet ejection amount for each color. Therefore, the piezoelectric element of each nozzle row is averaged by the conventional optimum driving voltage. It is possible to improve the print quality of color printing without causing a slight difference in color tones as compared with the case where is driven.

Furthermore, since the amplifiers 122A to 122N and the current amplification circuits 113A to 113N have the same amplification factor, the reproducibility of the driving waveform is the same between the nozzle rows, so that the printing quality of color printing is further improved. Can be improved.

FIG. 5 shows the essential parts of a second embodiment of the head drive device according to the present invention. 5, the head drive device 300 is the head drive device 10 shown in FIG.
Since the configuration is almost the same as 0, the same components are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 5, the head drive device 300 is
Voltage adjustment circuit 121A in the drive signal supply circuit 112
3 to 121N, the second resistors RA to RN are different from the head drive device 100 shown in FIG. 3 only in that the second resistors RA to RN are provided outside the IC forming the drive signal supply circuit 112.

According to the head drive device 300 having such a configuration, the same operation as the head drive device 100 shown in FIG. 1 is performed, and the second resistors RA to RN of the voltage adjusting circuits 121A to 121N are driven by the drive signals. Since the supply circuit 112 is provided outside the IC constituting the supply circuit 112, the components other than the second resistors RA to RN are not included in the drive signal supply circuit 1.
The second resistor R, which is to be incorporated in an IC that constitutes 12, is simple in configuration and requires adjustment of the resistance value.
ICs in which A to RN configure the drive signal supply circuit 112
Adjustment work becomes easy by being attached externally.

Further, the piezoelectric element 11 corresponding to each nozzle row
When the resistance values of the second resistors RA to RN that give the optimum drive voltage of 1 A to 111 N are determined, the fixed resistors are used as the second resistors RA to RN externally attached to the IC configuring the drive signal supply circuit 112. It is also possible to use

In the above-described embodiment, the case of an ink jet printer having N nozzle rows has been described, but the present invention is actually applied to an ink jet printer for performing color printing of, for example, 4 colors or 6 colors. It is clear to get.

In this case, for the four or six nozzle rows for each color, the voltage adjusting circuit 121 and the amplifier 122 corresponding to each nozzle row are provided in the drive signal supply circuit 112 to correspond to each nozzle row. Each voltage adjusting circuit 121 may be adjusted so as to give an optimum driving voltage to each piezoelectric element.

[0065]

As described above, according to the present invention, the drive signal for the piezoelectric element of each nozzle array is optimally driven by the voltage adjusting circuit in the drive signal supply circuit for the piezoelectric element of each nozzle array. Set to voltage. As a result, as compared with the conventional case where the piezoelectric element of each nozzle row is driven and controlled by the average value of the optimum drive voltage for the piezoelectric element of the nozzle row of each color for color printing, each nozzle row is controlled. The drive voltage of the drive signal applied to the piezoelectric element is set to the optimum drive voltage.

Further, since the amplification factors of the amplifiers corresponding to the respective nozzle rows are the same, the reproducibility of the waveform including overshoot and undershoot of the drive signal becomes the same between the nozzle rows.

Therefore, it is possible to improve the printing quality of color printing without causing the colors of the nozzle rows to be slightly different from each other.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the overall configuration of an ink jet printer using a head drive device of the present invention.

FIG. 2 is a functional block diagram showing an internal configuration of a drive waveform generation circuit in the inkjet printer shown in FIG.

FIG. 3 is a block diagram showing a configuration of a first embodiment of a head drive device according to the present invention.

FIG. 4 is a wiring diagram showing a specific configuration example of a current amplification circuit in the ink remaining amount detection device of FIG.

FIG. 5 is a block diagram showing a main part of a configuration of a second embodiment of a head drive device according to the present invention.

[Explanation of symbols]

100,300 Head drive device 111A to 1
11N Piezoelectric element 112 Drive signal supply circuit 113A to 113N
Current amplification circuit 114A to 114N Switch circuit 80 Waveform generation circuit 121A to 121N Voltage adjustment circuit 122A to 122N Amplifier

Claims (11)

[Claims] 1. A nozzle array corresponding to a plurality of nozzle arrays, each of which is provided with a corresponding piezoelectric element for applying pressure to ink and is selectively driven at a predetermined printing timing by a drive signal from a drive signal supply circuit. A head drive device for an ink jet printer that ejects ink droplets from a nozzle to perform recording, wherein the drive signal supply circuit outputs one waveform generation circuit and an output signal from the waveform generation circuit for each nozzle row. A head drive device for an ink jet printer, comprising: an amplifier that amplifies the input signal and a voltage adjusting circuit that adjusts a voltage of an input signal to each amplifier. 2. The head driving device for an ink jet printer according to claim 1, wherein the gains of all the amplifiers are constant. 3. The voltage adjusting circuit includes a first resistor connected in series between the waveform generating circuit and each amplifier, and a connection point between the first resistor and each amplifier and the ground. 3. The head drive device for an ink jet printer according to claim 1, wherein the head drive device is configured by: 4. The head driving device of an ink jet printer according to claim 3, wherein the first resistor is a fixed resistor and each of the second resistors is a variable resistor. 5. The drive signal supply circuit is composed of an IC, and each of the second resistors is provided outside an IC that constitutes the drive signal supply circuit. A head driving device for an ink jet printer according to claim 3. 6. An ink jet printer comprising the head driving device according to claim 1. Description: 7. A nozzle array corresponding to a plurality of nozzle arrays is driven by a drive signal from a drive signal supply circuit to selectively drive a piezoelectric element that applies pressure to ink, at a predetermined printing timing. A method for driving a head of an inkjet printer, in which ink droplets are ejected from an ink jet head to perform recording, comprising one waveform generation circuit and an amplifier that amplifies an output signal from the waveform generation circuit for each nozzle row. The drive signal supply circuit further adjusts the voltage of the input signal to each amplifier by the voltage adjustment circuit, and the drive signal applied to the piezoelectric element of each nozzle row is optimized for the piezoelectric element of each nozzle row. A method of driving a head of an ink jet printer, comprising adjusting the driving voltage. 8. The method for driving a head of an ink jet printer according to claim 7, wherein the gains of all the amplifiers are constant. 9. The voltage adjusting circuit includes a first resistor connected in series between the waveform generating circuit and each amplifier, and a connection point between the first resistor and each amplifier and a ground, respectively. 9. The head driving method for an ink jet printer according to claim 7, further comprising a second resistor connected thereto. 10. The first resistor is a fixed resistor,
Each of the second resistors is a variable resistor,
A method for driving a head of an inkjet printer according to claim 9. 11. The drive signal supply circuit is composed of an IC, and each of the second resistors is provided outside the IC constituting the drive signal supply circuit. Item 11. A method of driving a head of an inkjet printer according to Item 9 or 10.