JPH11221921A - Driving circuit of ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce costs of a driving voltage generating circuit by furnishing two sets of driving voltage generating circuits and two sets of analog switches to apply selectively driving voltage waveform to be generated, and connecting the two sets of the analog switches to one piezoelectric oscillator via each separate resistor. SOLUTION: Driving waveforms are inputted from each one end of analog switches 4-11 and 4-12, and the other end of each analog switch is connected to a piezoelectric oscillator 6-1 via respective resistors 5-11, 5-12. When only analog switch 4-11 is in a conducting state, a driving waveform 1 is applied to the piezoelectric oscillator 6-1, and when only analog switch 4-12 is in a conducting state, a driving waveform 2 is applied. Both of them are in a conducting state, an intermediate waveform is applied by voltage in which the driving waveform 1 and driving waveform 2 are put into partial pressure by the resistors 5-11 and 5-12. Thus, proper driving voltage can be selected among three kinds of these voltages.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a driving circuit for an ink jet head using a piezoelectric vibrator.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 7, an ink jet head has one or more nozzle rows in which a plurality of nozzles are arranged in one row. In an ink jet head using a piezoelectric vibrator, a driving circuit for driving the piezoelectric vibrator corresponding to each nozzle has a drive voltage applied to each piezoelectric vibrator of 1 as shown in the block diagram of FIG. One driving voltage generating circuit generates the driving voltage and selectively applies the driving voltage to a piezoelectric vibrator corresponding to a nozzle for discharging ink by a selection circuit including an analog switch or the like.

[0003]

For example, in the case of an ink jet head having a plurality of nozzle rows as shown in FIG. 7, since the piezoelectric vibrators are formed from the same base material in the same nozzle row, the discharge characteristics of the nozzles are as follows. Although almost constant, between different nozzle rows, the piezoelectric vibrators may be made of different base materials, so that the ejection characteristics of the nozzles may not be constant, leading to a decrease in print quality.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 9-109389 discloses a method as shown in FIG.
An integrated circuit for driving a recording element of an ink jet recording apparatus having a plurality of output pads and applying a driving voltage to a piezoelectric element for discharging ink from a nozzle of the ink jet recording apparatus, wherein a driving voltage is applied to each output pad. , Which can be controlled in a plurality of stages so as to be controllable.

However, the method disclosed in Japanese Patent Application Laid-Open No. 9-109389 requires a number of drive voltage generating circuits corresponding to the number of drive voltages that can be output, and has a problem that the circuit scale becomes large and the cost increases.

[0006]

In order to solve the above-mentioned problems, in a driving circuit for an ink jet head according to the present invention, two sets of driving voltage generating circuits and a driving voltage waveform generated by the driving voltage generating circuit are selected. And two sets of analog switches for applying power to each other, wherein the two sets of analog switches are connected to one piezoelectric vibrator through different resistors.

The ink jet head includes a plurality of nozzle groups each including a plurality of nozzles, and one or the other of the two sets of analog switches connected to the piezoelectric vibrator corresponding to the nozzles for each nozzle group. , Or both.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described in detail. FIG. 1 is a block diagram showing an embodiment of the present invention. The inkjet head 3 is configured so that the drive waveform generated by the drive waveform generation circuit 1 is selectively applied by the selection circuit 2. The drive waveform generation circuit 1 includes a drive waveform generation circuit 1-1 and a drive waveform generation circuit 1.
-2 drive waveform generating circuits. The two sets of drive waveform generating circuits respectively generate drive waveforms of two types of drive voltages as shown in FIG. The two types of drive waveforms operate even if they are arbitrary waveforms. However, in general, two types of drive waveforms differing only in voltage amplitude are output in order to correct variations in ink ejection amount.

FIGS. 3 and 4 show circuit examples of the selection circuit 2 and the ink jet head 3. FIG. FIG. 3 shows a circuit example of the selection circuit 2 and one element of the piezoelectric vibrator of the ink jet head 3. The drive waveform 1 of FIG. 5 generated by the drive waveform generation circuit 1-1 is input from one end of the analog switch 4-1 and the drive waveform generation circuit 1-2 of FIG. 5 generated from one end of the analog switch 4-2. The driving waveform 2 is input. The other end of each analog switch is connected to the piezoelectric vibrator 6-1 via a resistor 5-1 and a resistor 5-2, respectively.

According to the print data 1 and the print data 2,
When only the analog switch 4-1 is turned on, the driving waveform 1 is applied to the piezoelectric vibrator 6-1. When only the analog switch 4-2 is turned on, the driving waveform 2 is applied to the piezoelectric vibrator 6-1. Is done. When both the analog switch 4-1 and the analog switch 4-2 become conductive,
The voltage of the driving waveform 1 and the driving waveform 2 are applied to the piezoelectric vibrator 6-1.
5 is applied as the voltage divided by the resistor 5-1 and the resistor 5-2.

When the resistance values of the resistor 5-1 and the resistor 5-2 are set to the same value, the voltage amplitude of the driving waveform 3 becomes
Is set to an intermediate voltage amplitude between the drive waveform 1 and the drive waveform 2 in which the difference between the drive waveform 1 and the drive waveform 2 becomes equal.

As described above, according to the present invention, if there is a driving waveform generating circuit that generates driving waveforms of two types of driving voltages,
Driving waveforms of various driving voltages can be selectively applied to the piezoelectric vibrator.

FIG. 4 shows an example of a circuit corresponding to the selection circuit 2 and one nozzle row of the ink jet head 3. The circuits of FIG. 3 are used by the number corresponding to the number of nozzles of the ink jet head, and the print data corresponding to each nozzle row is provided by an independent shift register 7-1, 7-2,.
Is transferred as serial data.

The transferred data is stored in latches 8-1, 8-
2 are held by a latch signal, and latches 8-1, 8-
2 and the correction signal 1 and the correction signal 2 are output from an AND circuit 9-
11, 9-12, 9-21, 9-22,..., And analog switches 4-11, 4-12, 4-21, 4
-22 are controlled, and the piezoelectric vibrators 6-1, 6-2,... Have a drive waveform 1 or a drive waveform 2 corresponding to the correction signal, or a drive waveform having an intermediate voltage amplitude between the drive waveforms 1 and 2. 3 is selectively applied.

Since the circuit shown in FIG. 4 is configured for each nozzle row, by setting the correction signal 1 and the correction signal 2 in accordance with the ink ejection characteristics of each nozzle row, three types of driving voltages can be obtained. , An appropriate drive voltage can be selected.

As a method of selecting the driving voltages of the driving waveforms 1 and 2, the highest driving voltage among the appropriate driving voltages of all the nozzle rows is set to the driving voltage of the driving waveform 1, and the lowest one is set to the driving voltage of the driving waveform 2. Set to drive voltage.

The nozzle row having the highest drive voltage has drive waveform 1
Only the drive waveform 2 is applied to the nozzle row with the lowest drive voltage, and the other nozzle rows are set to the intermediate positions between the drive waveforms 1 and 2 and the two drive waveforms. By setting such that a drive waveform close to an appropriate drive voltage is applied from among the drive waveforms 3 that are drive voltages, it is possible to perform optimal correction of ink ejection characteristics between nozzle rows.

In the description of the present embodiment, the drive waveform has been described using the simplest drive waveform that rises once near the GND level and falls once after a certain time, but for example, as shown in FIG. Even if a driving waveform in which the potential at the start of the cycle is not near the GND level and rises and falls plural times during one cycle is used, it can be used without any problem.

[0019]

As described above, in the present invention, the difference in the ink ejection characteristics for each nozzle row can be corrected with a small-scale circuit, so that the ink ejection characteristics are stabilized and the print quality is improved. I do.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of the present invention.

FIG. 2 is a diagram showing driving waveforms according to the embodiment of the present invention.

FIG. 3 is a circuit diagram showing a selection circuit according to the embodiment of the present invention.

FIG. 4 is a circuit diagram showing a selection circuit according to the embodiment of the present invention.

FIG. 5 is a diagram showing driving waveforms according to the embodiment of the present invention.

FIG. 6 is a diagram showing driving waveforms according to the embodiment of the present invention.

FIG. 7 is a diagram showing a head configuration according to the related art.

FIG. 8 is a block diagram showing a conventional head drive circuit.

FIG. 9 is a diagram showing a printing element driving integrated circuit according to the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drive waveform generation circuit 2 selection circuit 3 inkjet head 4 analog switch 5 resistor 6 piezoelectric vibrator 7 shift register 8 latch 9 AND circuit

Claims (2)

[Claims] 1. A drive circuit for an ink jet head using a piezoelectric vibrator, wherein two sets of drive voltage generating circuits and two sets of analogs for selectively applying a drive voltage waveform generated by the drive voltage generating circuit are provided. A drive circuit for an ink jet head, comprising: a switch; wherein the two sets of analog switches are connected to one piezoelectric vibrator via different resistors. 2. A driving circuit for an ink jet head according to claim 1, wherein said ink jet head includes a plurality of nozzle groups each including a plurality of nozzles, and each of said nozzle groups is connected to said pressure transmitting vibrator corresponding to a nozzle. And a selecting means for selecting one or the other or both of the two sets of analog switches.