JP3097155B2 - Driving apparatus and driving method for inkjet print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving apparatus and a driving method for an ink jet print head.

[0002]

2. Description of the Related Art A conventional ink jet print head is:
A printing signal is applied to the piezoelectric element to expand the piezoelectric element, and ink droplets are ejected from nozzles by the dynamic pressure of ink generated at this time to form dots on printing paper.

[0003]

The problem to be solved by the present invention is that when the driving means cuts off the scanning voltage, the electric charge of the piezoelectric element is reduced by the discharge due to the insulation resistance of the piezoelectric element, and the ink is ejected. It is a point that affects

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to drive an ink jet print head having excellent ink ejection characteristics.
It is an object of the present invention to provide an apparatus and a driving method.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided a drive apparatus and method for an ink jet print head which prints a piezoelectric element.
Charges the piezoelectric element at a different timing than the timing
And applying a charging voltage to the piezoelectric element.
You.

[0006]

FIG. 1 is a circuit diagram of a first embodiment of the present invention. 1 is a scanning voltage input terminal, 2 is an all bit ON signal input terminal, 3 is an enable signal input terminal, 4 is a latch signal input terminal, 5 is a serial print signal input terminal, 6 is a clock input terminal for a shift register, and 7 is a shift. A register, 8 is a latch, 9 is an AND gate, 10 is an OR gate, 11 is a transfer gate, and 12 is a piezoelectric element.

(1) The serial print signal input from the serial signal input terminal 5 is converted into a parallel signal by the shift register 7 in synchronization with the clock signal input from the shift register clock input terminal 6.

(2) The print signal converted into the parallel signal is latched by the latch 8 when the latch signal is input from the latch signal input terminal 4.

(3) The latched print signal is connected to the enable signal input from the enable signal input terminal 3 and
A logical operation is performed by the D gate 9 to select a print timing.

(4) The transfer gate 11 turns ON and OFF according to the latched print signal, and the scanning voltage input from the scanning voltage input terminal 1 is applied only to the selected piezoelectric element 12.

(5) Piezoelectric element 12 to which scanning voltage is applied
Expands by discharging and charging according to the waveform of the scanning voltage to discharge ink.

Here, since the OR gate 10 is added, all the transfer gates are turned on by the all bit-on signal input from the all bit-on signal input terminal 2.
N and the scanning voltage is applied to all the piezoelectric elements.

At this time, as shown in the timing chart of FIG. 2, by applying the all-bits-on signal during a fixed period of time when the scanning voltage is high, regardless of the printing signal and without affecting the driving of the piezoelectric element. To charge the piezoelectric element 12.

The interval T [s] at which all the bit-on signals are given is arbitrary, but the potential difference V after t [s] at both ends of the piezoelectric element is obtained.
[V] is V = E ₀ (1−e ^{−t / RC} ) E ₀ : potential difference [V] between both ends of the piezoelectric element when t = 0 R: resistance of the piezoelectric element [Ω] C: resistance of the piezoelectric element Since it is obtained by the capacitance [F], for example, in order to reduce the potential difference between both ends of the piezoelectric element due to electric discharge to about 1% of E ₀ , T = −ln (0.01) · RC is a standard. .

Next, as a second embodiment, the second embodiment of the present invention will be described.
FIG. 3 shows a circuit diagram of the embodiment.

Reference numeral 13 denotes a scanning voltage input terminal, 14 denotes an enable signal input terminal, 15 denotes a latch signal input terminal, 16 denotes a serial print signal input terminal, and 17 denotes a shift register clock input terminal.

FIG. 4 is a timing chart of signals input to the input terminals of FIG. The circuit configuration is the first
In this embodiment, the serial print signal is latched as shown in the timing chart of FIG. 4 and then the serial print signal of all bits is input to the serial signal input terminal 16 as shown in the timing chart of FIG.

After printing with the latched print signal is completed, a latch signal is input to the latch signal input terminal 15 to latch the print signal of all bits on.

By inputting an enable signal to the enable signal input terminal 14 during a fixed period in which the scanning voltage until the next print signal is input is high and all the transfer gates 11 are turned on, all the piezoelectric elements are turned on. Charge 12

[0020]

According to the present invention, since all the piezoelectric elements are charged at a predetermined timing, even if a certain piezoelectric element is not driven, a decrease in the charge due to the discharge of the piezoelectric element is compensated.
There is no effect on ink ejection.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment of a drive circuit of an ink jet print head using the present invention.

FIG. 2 is a timing chart of a signal input to an input terminal of the circuit of FIG.

FIG. 3 is a circuit diagram of a second embodiment of a drive circuit for an ink jet print head using the present invention.

FIG. 4 is a timing chart of a signal input to an input terminal of the circuit of FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 scanning voltage input terminal 2 all bit ON signal input terminal 3 enable signal input terminal 4 latch signal input terminal 5 serial print signal input terminal 6 shift register clock input terminal 7 shift register 8 latch 9 AND gate 10 OR gate 11 transfer gate 12 Piezoelectric element 13 Scan voltage input terminal 14 Enable signal input terminal 15 Latch signal input terminal 16 Serial print signal input terminal 17 Clock input terminal for shift register

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/01 B41J 2/055

Claims (6)

(57) [Claims] An ink jet print head driving device for selectively driving a piezoelectric element provided for each of a plurality of nozzles at a predetermined printing timing and ejecting ink droplets from the nozzle to perform recording. At a timing different from the printing timing of the piezoelectric element,
Applying a charging voltage for charging the piezoelectric element to the piezoelectric element compensates for a decrease in charge due to discharge of the piezoelectric element.
And a piezoelectric element charging means. 2. A scanning voltage waveform is selected at a predetermined printing timing by a piezoelectric element provided for each of a plurality of nozzles.
By selectively driving the piezoelectric element by doing, a driving device of an ink jet print head that performs recording by discharging ink droplets from the nozzle, at a timing different from the printing timing of the piezoelectric element,
And a piezoelectric element charging means for charging the piezoelectric element during a period in which the scanning voltage waveform is constant . 3. The ink jet print head drive device according to claim 1, wherein the piezoelectric element charging means charges all the piezoelectric elements at the same timing. 4. A method for driving an ink-jet print head in which a piezoelectric element provided corresponding to each of a plurality of nozzles is selectively driven at a predetermined printing timing and ink droplets are ejected from the nozzles to perform recording. At a timing different from the printing timing of the piezoelectric element,
Applying a charging voltage for charging the piezoelectric element to the piezoelectric element compensates for a decrease in charge due to discharge of the piezoelectric element.
The driving method of an ink jet print head, characterized in that the Hare. 5. A scanning voltage waveform is selected at a predetermined printing timing for a piezoelectric element provided for each of a plurality of nozzles.
A method for selectively driving the piezoelectric element by ejecting ink droplets from the nozzles to perform recording, wherein the print timing of the piezoelectric element is different from the print timing of the piezoelectric element.
A method for driving an ink jet print head , wherein the piezoelectric element is charged during a period in which the scanning voltage waveform is constant . 6. The method according to claim 4, wherein the piezoelectric element charging means charges all the piezoelectric elements at the same timing.