JPH11268306A - Color recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suffice a power source circuit by one system, reduce costs, apply an appropriate driving voltage for each color head and improve color record quality by shifting a timing for driving a head for each color during color recording and setting the driving voltage for each color. SOLUTION: A voltage to be impressed to printing heads 61-64 via a head driver 21 from a driving power source 30 is made variable according to each color printing head. Moreover, an impression timing is shifted for each printing head 61-64. In comparison with the case where a separate driving voltage source is used for each printing head 61-64, one system is enough for the driving power source, costs can be reduced and an optimum driving voltage can be impressed according to the printing heads.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color recording apparatus applied to a printer, a copier, and the like, and more particularly to a technique for simplifying a power supply for driving a recording head.

[0002]

2. Description of the Related Art Conventionally, there has been a color recording apparatus for recording a color image by ejecting inks of a plurality of colors by an ink jet system, a thermal transfer system or the like. This recording apparatus is provided with a head driver having a plurality of recording heads (print heads). The head driver applies a predetermined drive voltage to an actuator of the print head based on image data to perform printing. Drive the head.
As a print head of a plurality of colors, for example, in the case of full color, heads of four color inks of yellow, magenta, cyan and black are used.

However, the print head of each color in this type of color recording apparatus has variations in output characteristics, and the physical properties of the ink itself vary depending on the color and type. When a head is driven to record a color image, the color balance may be lost or the color tone reproducibility may be degraded. Therefore, it is known to control the drive of the print head to match the print characteristics of the print head. For example, when using a head that generates a pressure wave by utilizing the electro-mechanical conversion action of a piezoelectric element and ejects ink from an ejection port as a print head, the voltage applied to the piezoelectric element is adjusted according to the recording characteristics of the print head. It is known that the size of the ejected ink droplet is controlled by controlling the size of the ink droplet, thereby correcting the color balance and the like (see, for example,
167755).

[0004]

However, in the above-described conventional apparatus, a print signal is applied in order to apply an appropriate drive voltage to each of the print heads of a plurality of colors in accordance with the print characteristics of the print head. It is necessary to have a complicated configuration in which a plurality of tables are used to select and set an appropriate applied voltage from information on the discharge characteristics of the print head, or a plurality of power supplies are used to set a drive voltage for each print head. When the number of systems increases, the circuit scale of the power supply system increases, which leads to an increase in the cost of the recording apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and a power supply circuit is provided by setting the drive voltage for each color by shifting the head drive timing of each color in color printing. It is an object of the present invention to provide a color printing apparatus capable of improving the color printing quality, in which only one system is required, cost can be reduced, and an appropriate driving voltage can be applied to each head of each color.

[0006]

Means for Solving the Problems and Effects of the Invention In order to achieve the above object, the invention according to claim 1 comprises an ink chamber filled with ink for each of a plurality of color inks, and an ink chamber in the ink chamber. A printhead having an actuator that applies pressure to the nozzles to eject ink from the nozzles, and a driver that applies a drive voltage from a drive voltage source to the actuators of the printheads of the respective colors in accordance with a one-dot unit ejection command. Control means for outputting an ejection command for each dot to the driver based on image data, wherein the control means outputs a voltage applied to the recording head from a driving voltage source via the driver to each color. And the timing is shifted for each recording head.

According to the present invention, the control means applies a drive voltage corresponding to the recording head of each color by shifting the timing from one driving voltage source via the driver via the driver. Compared to the case where a driving voltage source is used, only one driving power supply is required, cost can be reduced, and an optimum driving voltage can be applied according to the head, so that color recording quality can be maintained and excellent Color balance and color gradation reproduction can be obtained.

[0008] The invention described in claim 2 is the first invention.
The color recording apparatus according to claim 1, further comprising a voltage conversion table that outputs voltage conversion data for varying the drive voltage output from the drive voltage source, wherein the control unit controls the voltage conversion table for each color of the ejection command. And outputs a table data selection signal corresponding to.

According to the present invention, the control means outputs a table data selection signal corresponding to each color of the injection command, and based on this, voltage conversion data corresponding to each color is output from the voltage conversion table. The driving voltage source applies a predetermined driving voltage to the head based on the driving voltage. Therefore, only by having one voltage conversion table, it is possible to easily apply a drive voltage suitable for the head of each color with a simple power supply system, and the same operation and effect as described above can be obtained.

[0010] Further, the invention described in claim 3 is based on claim 2.
In the color printing apparatus described in the above, the data of the voltage conversion table can be freely rewritten from outside. According to the present invention, in addition to the above-described functions and effects, the data in the voltage conversion table can be rewritten according to the output characteristics of the recording head for each color, so that the recording head and the ink can be easily replaced. It is possible to

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating an electrical configuration of an inkjet printer according to an embodiment of the color recording apparatus. The control device of the ink jet printer is a microcomputer 11 (CP
U), a ROM 12, and a RAM 13. The microcomputer 11 includes an operation panel 14 for a user to issue a print instruction and the like, and a motor drive circuit 1 for driving a carriage motor 506 equipped with a print head.
5, a motor drive circuit 16 for driving an LF motor 510 that conveys a recording sheet as a recording medium, a paper sensor 17 for detecting the leading edge of the recording sheet, and an origin sensor for detecting the origin position when printing on the recording sheet 18 etc. are connected.

The print head 60 (recording head) is driven by a head driver 21 (driver). The head driver 21 is controlled by a control circuit 22 (control means) to generate a drive signal suitable for the print head 60 and Apply to head. The print head 60 includes heads 61 to 64 of four colors of black (K), yellow (Y), cyan (C), and magenta (M), and is provided with an electrode (not shown) in an ink chamber provided for each head. A driving voltage is applied from the head driver 21. Microcomputer 11 and ROM1
2, the RAM 13 and the control circuit 22 include an address bus 23
And a data bus 24. The microcomputer 11 generates a print start signal and a reset signal according to a program stored in the ROM 12 in advance, and transfers each signal to the control circuit 22.

The head driver 21 includes a print head 60.
A driving power supply 30 (driving voltage source) for generating a driving voltage is connected, and a predetermined driving voltage is applied from the driving power supply 30 to the print head 60 via the head driver 21. A voltage conversion table 31 is connected to the drive power supply 30. The voltage conversion table 31 is an 8-bit table based on a 2-bit table data selection signal output from the control circuit 22 (see FIGS. 2 and 3). It outputs voltage conversion data (see Table 1 below) to the drive power supply 30. Further, the voltage conversion table 31 receives rewrite data from the microcomputer 11 and can arbitrarily rewrite the data in the table.

The control circuit 22 is constituted by a gate array, and based on image data stored in the image memory 25 in accordance with a print start signal and a reset signal.
It generates print data for forming the image data on a recording medium, a transfer clock synchronized with the print data, a strobe signal, and a print clock, and transfers these signals to the head driver 21 in synchronization with the carriage encoder signal. . Thereby, the control circuit 22 sends an ink ejection command for each dot based on the image data to the head driver 2.
1 for the head driver 21
Is the driving power supply 3 in accordance with the one-dot unit ejection command.
The drive voltage output from 0 is applied to the actuator of each print head 60. In addition, the microcomputer 11
Causes the image memory 25 to store image data transferred from an external device such as a personal computer via the Centro interface 20.

FIG. 2 shows a driving power supply 30 and a head driver 2.
FIG. 2 is a block diagram showing a detailed configuration of the first embodiment. The head driver 21 includes, for example, 64 print heads of each color.
It drives a 64-channel multi-nozzle head having a chamber ink chamber. Head driver 21
Has circuits corresponding to the heads of four colors, and although not shown in detail, each includes a serial-parallel converter, a data latch, an AND gate, and an output circuit.
Print data serially transferred in synchronization with the transfer clock from the printer is input, and the print data is converted into parallel data in accordance with the rise of the transfer clock, thereby performing serial-parallel conversion of the print data.

The drive voltage from the drive power supply 30 is applied to each output circuit of the head driver 21, and through this, each drive circuit is synchronized with the clock signal of each color from the print data signal generation circuit 27 of the control circuit 22. The voltage is applied to the heads 61 to 64. Here, the print data signal generation circuit 27 of the control circuit 22 generates a clock signal by shifting the time timing for each of the recording heads 61 to 64.
The drive power supply 30 is provided with a digital / analog (D /
A) A voltage conversion table 3 comprising a converter and an amplifier
The 8-bit voltage conversion data set in advance for each color output from 1 is received, D / A converted, the amplifier is operated, and the drive of the setting which is changed according to the print heads 61 to 64 of each color is received. It outputs a voltage.

Next, in the ink jet printer of the present embodiment configured as described above, the operation of driving the print head 60 by the microcomputer 11, the control circuit 22, the drive power supply 30, and the head driver 21 will be described with reference to FIGS. This will be described with reference to FIG. FIG. 3 is a timing chart of the operation, and FIG. 4 shows the driving power supply characteristics. As shown in FIG. 3, the control circuit 22 outputs a 2-bit table data selection signal corresponding to the clock signal of each color, and supplies it to the voltage conversion table 31. The table data selection signal is set in advance for each color so that the optimum drive voltage corresponding to the print heads 61 to 64 for each color is output from the drive power supply 30. Based on the table data selection signal, 8-bit voltage conversion data is input from the voltage conversion table 31 to the driving power supply 30. The drive power supply 30 generates a drive voltage of an analog value of the voltage conversion data and outputs the drive voltage to the head driver 21. The drive voltage is selectively applied to the print head 6 in synchronization with the clock signal of each color.
1 to 64. The following table shows the 8-bit voltage conversion data output by the voltage conversion table 31 and the driving voltage from the driving power supply 30 based on the data.

[0018]

Table 1 8-bit voltage conversion data Optimum drive voltage Black E6h 28.5 (V) Yellow D5h 27.2 (V) Cyan E0h 28.0 (V) Magenta D9h 27.6 (V)

Here, the print data signal generation circuit 27 of the control circuit 22, based on the timing signal (print start signal) given from the microcomputer 11, as shown in FIG. The clock signal is generated with the time timing shifted. As a result, a predetermined drive voltage can be applied from one drive power supply 30 to each of the print heads 61 to 64. Therefore, the power supply system does not increase, and simplification and cost reduction can be achieved. In addition, it is possible to easily apply an optimum drive voltage that matches the characteristics of the print heads 61 to 64 for each color, and it is possible to perform recording with good color balance and color gradation reproduction.

The data of the voltage conversion table 31 can be arbitrarily rewritten by rewriting data 26 from the microcomputer 11. Therefore, when the print head 60 and the ink are replaced, it is possible to easily cope with the print head 60 after the replacement according to the characteristics of the print head 60. Further, information on the proper drive voltage for the head of each color, which is set in consideration of the physical properties of the ink of each color and the fluctuation characteristics of the physical properties with respect to the temperature condition, etc.
Alternatively, the voltage conversion table 31 may be stored in the RAM 13 in advance, and the microcomputer 11 may store the voltage conversion table 31 based on this information.
May be rewritten.

Further, since the timing of the print clock signal is shifted for each color as described above, if there is a problem in print quality, the nozzle positions of the print heads 61 to 64 for each color are changed to the above timing. It is conceivable to displace them in consideration of the displacement. However, even if the signal timing is shifted, if the line head is used, the paper feed is stopped for each line, or if the moving speed of the carriage is sufficiently slow with respect to the shift in the drive timing of each head. Does not hinder print quality, and there is no need to shift the nozzle position of the print head.

Note that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example,
(1) In the above embodiment, a print head using an actuator using a piezoelectric material is shown. In this case, the configuration of the print head is simplified, and the durability and the manufacturing cost are reduced. However, the present invention is not limited to the piezoelectric method, and can be similarly applied to recording heads of various driving methods such as a thermal head method and a bubble jet method. (2) The present invention has been described with reference to the case of a full-color printing apparatus in the above embodiment, but the present invention is similarly applicable to a mono-color printing apparatus using a print head of two or more colors.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is a block diagram of a power supply system that drives a recording head of the inkjet printer according to the embodiment.

FIG. 3 is a diagram showing a timing chart of signals for driving a recording head.

FIG. 4 is a diagram showing driving voltage characteristics of a driving power supply.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Microcomputer 21 ... Head driver 22 ... Control circuit 30 ... Drive power supply 31 ... Voltage conversion table 60, 61-64 ... Printing head (recording head)

Claims (3)

[Claims] A recording head having an ink chamber filled with ink for each of a plurality of colors of ink; an actuator for applying pressure to the ink in the ink chamber to eject ink from nozzles; A driver that applies a drive voltage from a drive voltage source to actuators of the recording heads of the respective colors in response to an ejection command; and control means that outputs an ejection command in units of one dot to the driver based on image data. In the color printing apparatus, the control means varies the voltage applied to the printhead from the drive voltage source via the driver according to the printhead of each color, and applies the voltage at a shifted timing for each printhead. A color recording apparatus characterized by the above-mentioned. 2. The apparatus according to claim 1, further comprising: a voltage conversion table for outputting voltage conversion data for varying a driving voltage output from the driving voltage source, wherein the control unit controls the voltage conversion table for each color of an ejection command. 2. The color printing apparatus according to claim 1, wherein a table data selection signal is output in response to the data. 3. The color printing apparatus according to claim 2, wherein the data of the voltage conversion table can be freely rewritten from outside.