JPH04316851A - Drive circuit of ink jet multinozzle head - Google Patents

Abstract

PURPOSE:To provide an ink jet multinozzle head which can be miniaturized because of a simple circuit and is of a low cost. CONSTITUTION:The title drive circuit of an ink jet multinozzle head is equipped with a shift register 14 which outputs pulse signals Q1-Qn generated by synchronizing a data with a specific clock signal CP, a plurality of data circuits 131-13n which modulate pulse widths of pulse signals Q1-Qn outputted from output terminals 141-14n of the shift register 14 based on a common pulse signal PWM outputted from a pulse width generating circuit 15, and a plurality of high pressure proof amplifiers 111-11n which impress voltage to a plurality of piezoelectric elements PZT1-PZTn based on the pulse signal PWM modulated with a plurality of date circuit 131-13n.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for an inkjet multi-nozzle head that drives a plurality of piezoelectric elements that eject ink from a plurality of nozzles.

0002

[Prior Art] Conventional methods for expressing gradations using inkjet include an area gradation method in which the number of dots per unit area is changed according to the gradation, and a method that is advantageous for on-demand type dots. By controlling the driving voltage or driving time of the piezoelectric element to eject ink from the nozzle according to the gradation, while keeping the number constant, the amount of ink that forms one dot is changed, and the size of the dot can be adjusted to the gradation. A dot changing method is known in which the dots are changed accordingly.

Although the area gradation method described above has the disadvantage that resolution must be sacrificed in order to increase the number of gradations, the dot change method described above is superior in this respect.

The above dot changing method will be explained below with reference to FIG.

FIG. 5 shows a piezoelectric element drive circuit using the dot change method. High voltage power supply 21 for high voltage amplifier 20
is connected, and when a pulse signal is input from the pulse width setting circuit 22, a high voltage pulse is generated by the voltage of the high voltage power supply 21 and applied to the piezoelectric element 23. The width of the high voltage pulse applied to the piezoelectric element 23 is controlled by a pulse width setting circuit 22.

FIG. 6 shows an example of the configuration of another drive circuit, in which a voltage is applied to the high voltage amplifier 24 from an applied voltage setting circuit 25 so as to generate a high voltage pulse, and when the head is turned on.
−When the OFF signal is turned on, the applied voltage setting circuit 2
A high voltage pulse with a voltage value set by 5 is applied to piezoelectric element 2.
6.

[0007]

[Problems to be Solved by the Invention] However, in a piezoelectric element drive circuit using the conventional dot changing method described above, it is effective to form a head with a plurality of nozzles, that is, a multi-nozzle head when increasing the recording density. In Although,
It is necessary to provide a drive circuit as shown in FIG. 5 or 6 for each piezoelectric element, which results in a problem that the entire circuit becomes complicated and large, resulting in high cost.

The present invention has been made in view of the problems in the conventional inkjet multi-nozzle head drive circuit described above.
To provide a drive circuit for an inkjet multi-nozzle head that has a simple circuit structure, can be miniaturized, and is inexpensive.

[0009]

[Means for Solving the Problems] The present invention provides pulse output means for outputting a pulse signal generated by synchronizing data with a predetermined clock signal, and a pulse width of the pulse signal output from the pulse output means. Comprising: a plurality of logic circuits that modulate based on a common control signal output from the generation means; and a voltage amplification means that applies voltage to the plurality of piezoelectric elements based on pulse signals modulated by the plurality of logic circuits. This is achieved by an inkjet multi-nozzle head drive circuit.

The present invention also provides pulse output means for outputting a pulse signal generated by synchronizing data with a predetermined clock signal; and voltage amplification means that modulates a voltage value based on pulse signals output from the plurality of logic circuits and applies the modulated voltage value to each of the plurality of piezoelectric elements. This can also be achieved by a drive circuit for an inkjet multi-nozzle head.

[0011]

[Operation] According to the first invention, the pulse output means outputs a pulse signal generated by synchronizing data with a predetermined clock signal, and each of the plurality of logic circuits outputs a pulse signal output from the pulse output means. The pulse width of the piezoelectric element is modulated based on a common control signal output from the pulse width generating means, and the voltage amplifying means applies voltage to the plurality of piezoelectric elements based on the pulse signal modulated by the plurality of logic circuits.

According to the second invention, the pulse output means outputs a pulse signal generated by synchronizing data with a predetermined clock signal, and the plurality of logic circuits convert the pulse signal output from the pulse output means into pulses. The voltage amplification means modulates the voltage value based on the pulse signals output from the plurality of logic circuits, and applies the modulated voltage value to each of the plurality of piezoelectric elements.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an inkjet multi-nozzle head drive circuit according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the configuration of an embodiment of a drive circuit for an inkjet multi-nozzle head according to the present invention.

The drive circuit of the inkjet multi-nozzle head shown in FIG. 1 includes a piezoelectric element section PZT formed by a plurality of piezoelectric elements PZT1 to PZTn, and a plurality of high voltage amplifiers 111 to 11n which are plural voltage amplification means. A high withstand voltage amplifier section 11, a control voltage generation circuit 12, and a plurality of gate circuits 131 to 1 which are logic circuits.
3n, a shift register 14 which is a pulse generation means, and a pulse width generation circuit 15 which is a pulse width generation means.

Each of the piezoelectric elements PZT1 to PZTn is driven by applying a voltage to eject ink from each nozzle (not shown).

Each of the high voltage amplifiers 111 to 11n is supplied with a high voltage VH having a constant value as a power source from the control voltage generation circuit 12, and each of the gate circuits 131 to 1
When pulse signals are input from 3n, each piezoelectric element PZT1 to PZT
Apply n10 high voltage.

Each gate circuit 131 to 13n is an AND circuit, and one input terminal of each gate circuit 131 to 13n is the output terminal 141 to 1 of the shift register 14.
4n, and the other input terminals are all connected to the output terminal of the pulse width generation circuit 15.

The shift register 14 inputs the clock signal CP, takes in the data signal DAT in synchronization with the rising edge of the input clock signal CP, shifts the taken data signal DAT, and sequentially outputs it from the output terminals 141 to 14n. Output.

The pulse width generation circuit 15 receives the clock signal C
A pulse signal PWM is output in synchronization with the rise of P, and each piezoelectric element PZ is controlled based on the width of the output pulse signal PWM.
Set the width of the high voltage pulse applied to T1 to PZTn.

Next, the operation will be explained using the timing chart shown in FIG.

When the data signal DAT is input, the shift register 14 takes in the data signal DAT, and in synchronization with the rising edge of the clock signal CP, outputs pulse signals Q1 to Qn having a width of one cycle of the clock signal CP. 141 ~
The data is output in order starting from 14n.

The pulse width generation circuit 15 receives the clock signal C
In synchronization with the rising edge of P, a pulse signal PWM having a width shorter than one period of the clock signal CP is output, and the pulse signal PWM
The pulse widths Tw1 to Twn are set based on gradation data that determines the gradation of the printed image for each pulse signal PWM.

Each of the gate circuits 131 to 13n outputs a pulse signal PWM when a pulse signal is input from the shift register 14, and outputs a pulse signal PWM to each corresponding high voltage amplifier 111.
Output to ~11n.

As a result, each high-voltage amplifier 111 to 11n to which the pulse signal PWM is applied receives a high-voltage pulse V of a constant voltage whose duration is equal to the pulse width of the pulse signal PWM.
1 to Vn are applied to the corresponding piezoelectric elements PZT1 to PZTn, respectively.

The piezoelectric elements PZT1 to PZTn are driven by the applied high voltage pulse, and an amount of ink corresponding to the duration of the high voltage pulse is ejected from the nozzle.

Next, another embodiment of the inkjet multi-nozzle head drive circuit of the present invention will be described.

FIG. 3 shows a drive circuit for the inkjet multi-nozzle head of this embodiment. Note that the same components as those in the embodiment described above are given the same reference numerals.

The difference between the drive circuit of FIG. 3 and the drive circuit of FIG. 1 is that the pulse signal P which is the output of the pulse width generation circuit 16
The point is that the level of WM' is kept at a constant value. That is, the control voltage generation circuit 17 applies a pulse-like high voltage Vp whose voltage varies depending on the gradation data to each high voltage amplifier 111 to 11n in synchronization with the rising edge of the clock signal CP, and the pulse width generation circuit 16 , piezoelectric elements PZT1 to PZT
When driving n, the pulse signal PWM' is fixed at a constant high level.

Next, the operation of the drive circuit shown in FIG. 2 will be explained with reference to the timing chart shown in FIG.

When the data signal DAT is input, the shift register 14 takes in the data signal DAT, and in synchronization with the rising edge of the clock signal CP, outputs pulse signals Q1 to Qn having a width of one cycle of the clock signal CP. 141 ~
The data is output in order starting from 14n.

The pulse width generation circuit 16 generates a pulse signal PWM.
' is fixed at a high level, and pulse signals Q1 to Qn are sequentially outputted from the gate circuit 13 based on the pulse signal PWM' and given to each corresponding high voltage amplifier 11.

The control voltage generation circuit 17 generates a pulsed high voltage having different voltages depending on the gradation data as a clock signal CP.
The pulse-like high voltage from the control voltage generation circuit 17 is applied to each high-voltage amplifier 111-11n in synchronization with the rising edge of the control voltage generating circuit 17. Each piezoelectric element P corresponds to high voltage pulses Vp1 to Vpn based on Vp.
A high voltage pulse Vp1 is applied to each of ZT1 to PZTn.
Each of the piezoelectric elements PZT1 to PZTn to which Vpn is applied is driven, and the nozzle discharges an amount of ink corresponding to the voltage Vp of the high-voltage pulse.

[0034]

Effects of the Invention The inkjet multi-nozzle head drive circuit of the first invention comprises a pulse output means for outputting a pulse signal generated by synchronizing data with a predetermined clock signal, and a pulse signal output from the pulse output means. a plurality of logic circuits that modulate the pulse width of the pulse width based on a common control signal output from the pulse width generation means, and a voltage that applies voltage to the plurality of piezoelectric elements based on the pulse signals modulated by the plurality of logic circuits. The circuit that controls the pulse width of the voltage applied to the piezoelectric element to change the amount of ink ejected from the nozzle is common to all piezoelectric elements. As a result, the entire circuit becomes simpler and smaller, resulting in lower costs.

The inkjet multi-nozzle head drive circuit according to the second aspect of the invention also includes a pulse output means for outputting a pulse signal generated by synchronizing data with a predetermined clock signal, and a pulse signal output from the pulse output means. a plurality of logic circuits that output the voltage based on a common control signal output from the pulse width generating means, and a voltage value modulated based on the pulse signal output from the plurality of logic circuits to each of the plurality of piezoelectric elements. When controlling the voltage value of the voltage pulse to change the amount of ink ejected from the nozzle, the circuit that sets the voltage value of the voltage pulse is shared, and the circuit The entire structure is simple and compact, resulting in lower costs.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of a drive circuit for an inkjet multi-nozzle head according to the present invention.

FIG. 2 is a timing chart for explaining the operation of the drive circuit in FIG. 1;

FIG. 3 is a circuit diagram showing the configuration of another embodiment of the inkjet multi-nozzle head drive circuit according to the present invention.

FIG. 4 is a timing chart for explaining the operation of the drive circuit in FIG. 3;

FIG. 5 is a circuit diagram showing a configuration example of a conventional nozzle head drive circuit.

FIG. 6 is a circuit diagram showing another configuration example of a conventional nozzle head drive circuit.

[Explanation of symbols]

PZT1~PZTn Piezoelectric element 111 ~ 11n High voltage amplifier 12 Control voltage generation circuit 131 ~ 13n Gate circuit 14 Shift register 15 Pulse width generation circuit

Claims (2)

[Claims] 1. Pulse output means for outputting a pulse signal generated by synchronizing data with a predetermined clock signal;
a plurality of logic circuits that modulate the pulse width of the pulse signal output from the pulse output means based on a common control signal output from the pulse width generation means; and the pulse signal modulated by the plurality of logic circuits. 1. A drive circuit for an inkjet multi-nozzle head, comprising: voltage amplification means for applying a voltage to a plurality of piezoelectric elements based on. 2. Pulse output means for outputting a pulse signal generated by synchronizing data with a predetermined clock signal;
a plurality of logic circuits that output the pulse signals output from the pulse output means based on a common control signal output from the pulse width generation means; and a plurality of logic circuits that output the pulse signals output from the plurality of logic circuits. 1. A drive circuit for an inkjet multi-nozzle head, comprising: voltage amplification means that modulates a voltage value and applies the modulated voltage to each of the plurality of piezoelectric elements.