JPH08216406A - Ink discharge recording device - Google Patents

Abstract

PURPOSE: To obtain an energization type ink jet printer with a head which is small in size and has a long service life. CONSTITUTION: In a discharge section 1, electrodes for supplying electric current to a conductive ink is made to be common among adjacent nozzles. An electric signal to be supplied to the electrodes from driving circuits D1-D6 of a supply section 2 is made to be alternating current. The phase of the electric signal is made to be the same among the electrodes of the adjacent discharge nozzles such that the electric current does not flow to the conductive ink of the nozzle which does not supply the current. Further, in a control section 3, the frequency of the current signal to be supplied to the electrodes from the driving circuits D1-D6 of the supply section 2 is temporarily doubled in such a manner that direct current, which causes deterioration of the electrodes when the driving times of the nozzles are different, does not flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer used for output printing of an office computer, a personal computer or the like, and in particular, a thermal action is applied to ink to cause ink boiling to cause ink flying. The present invention relates to a thermal type inkjet printer device that performs the thermal method.

[0002]

2. Description of the Related Art As a conventional device, a device described in US Pat. No. 3,179,042 shown in FIG. 8 is known.
In FIG. 8, 35 is conductive ink, 36 is an ink chamber filled with conductive ink 35, and 37 is conductive ink 35.
, A pair of electrodes arranged below the conductive ink surface, 40 a power source, 41 a switch for the power source 40, 42 a nozzle for discharging conductive ink, and 43 a covered The printing surface, 44 is an ink droplet ejected from the nozzle 42. When a voltage is applied to the pair of electrodes 38, 39, a current flows through the conductive ink 35, and the Joule heat of the conductive ink 35 vaporizes part of the conductive ink 35 between the tips of the electrodes 38, 39. Furthermore, the vaporized vapor of the conductive ink 35 expands until a sufficient pressure is generated to eject the ink droplet 44 from the nozzle 42 onto the printing surface 43. By selecting an electrode to which a voltage is applied by the switch 41, a nozzle hole for ejecting the conductive ink 35 is selected and a desired character can be formed on the surface 43 to be printed.

[0003]

However, in the above-mentioned conventional configuration, no consideration is given to the deterioration of the electrodes due to electrolysis that occurs when the ink is energized, and the configuration and control of the multi-nozzle.

The object of the present invention is to solve these problems,
An object of the present invention is to provide a compact and long-life ink discharge recording apparatus by a multi-head having a simple structure and simple control.

[0005]

In order to solve the above-mentioned problems, the ink discharge recording apparatus of the present invention fills the liquid passages corresponding to the respective multi-nozzles with conductive ink to separate the adjacent liquid passages. A part of the liquid passage wall was used as an electrode for electrically heating the conductive ink, and this electrode was made common to two liquid passages adjacent to each other. Further, when the supply unit that supplies the electric signals supplies the electric signals to the electrodes of the nozzles in the nozzle row at different timings, the electric signals being supplied to the electrodes at the start and end of the supply of the electric signals Frequency is normal 2 for a certain period
Double control is performed so that a direct current does not flow between these electrodes for a certain period of time or more to prevent deterioration of the electrodes due to electrolysis.

[0006]

With the above structure, the common electrodes are provided on the walls of the adjacent liquid passages, so that the liquid passage distance of the multi-nozzle head can be shortened, and the electrode structure and the wiring of the electrode wiring are very simple. Therefore, a high-density and compact ink ejection device can be realized. In addition, since a direct current does not flow through the electrode for a certain period or more, deterioration of the electrode due to electrolysis is prevented, and the life is extended.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an ink discharge recording apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 surrounded by a wavy line is an ejection portion for ejecting ink for printing, and this example corresponds to five nozzle holes, and R1 to R5 communicate with each nozzle. The ink resistance between the electrodes provided in the liquid path is shown. Reference numeral 2 surrounded by a broken line is a supply unit that supplies an electric signal to the electrode of the ejection unit 1, and D1 to D6 are drive circuits that configure the supply unit 2. OE1 to OE6 are output high impedance control signals of the drive circuits D1 to D6, and A1 to A6 are output level control signals. Reference numeral 3 is a control unit for controlling the supply unit 2, P1 to P5 are print timing signals corresponding to the respective nozzles, and the control unit 3 outputs high impedance control signals OE1 to OE6 according to the print timing signals P1 to P5. And the output level control signals A1 to A6 are output to control the supply unit 2.

FIG. 2 is a cross-sectional perspective view showing an example of the discharge section 1 shown in FIG. In FIG. 2, 4a, 4b, 4c are liquid passage walls, 5a, 5b, 5c are electrodes forming part of the liquid passage wall, 6a, 6b, 6c are nozzle holes, 7a, 7b, 7
c is a liquid path, and 8a is a common ink chamber. Liquid channels 7a, 7
b, 7c and the common ink chamber 8a are filled with conductive ink, and I represents a current flowing through the conductive ink. The liquid passage 7a is formed by the liquid passage wall 4a including the electrode 5a and the liquid passage wall 4b including the electrode 5b, and the liquid passage 7b is formed by the liquid passage wall 4b including the electrode 5b and the liquid passage wall 4c including the electrode 5c. Has been done. Therefore, the electrode 5b is an electrode common to the liquid paths 7a and 7b. In this way, the electrodes are common to both adjacent liquid paths of the nozzle head. For example, +,-, + ...
When an electric signal which is alternately repeated is supplied, and at the same time an electric signal whose phase is different by −180 degrees from −, +, −, ... Is supplied to the conductive ink filled in between the electrodes 5c and 5b. An alternating current flows as indicated by, and heat is generated / boiling due to the resistance component of the conductive ink, and the conductive ink is ejected from the nozzle hole 6b.

FIG. 3 is a circuit diagram showing an example of the drive circuit. FETs 1 and 2 are N-channel FET transistors, F
ET3 is a P-channel FET transistor, R6 and R7 are resistors, 9a and 9b are gate circuits, OE is an output high impedance control signal input, A is an output level control signal input, and O is an electrical signal output supplied to the ejection unit 1, Vcch is a power source and GND is a circuit ground.

(1) When OE is at L level The outputs of the gate circuits 9a and 9b are at L level regardless of the level of A, the FETs 1 and 2 are turned off, and when the FET 1 is turned off, the gate potential of the FET 3 becomes the same potential as Vcch. Because F
ET3 is also turned off and the output O becomes a high impedance output.

(2) OE and A are "H",
In case of "H" level: The outputs of the gate circuits 9a and 9b are "H" and "L", respectively.
The level becomes FET1, the FET1 is on, and the FET2 is off. When the FET1 is turned on, a current flows from the power supply Vcch to the circuit ground GND, so that the gate potential of the FET3 becomes a predetermined value determined by the resistors R6 and R7.
T3 is turned on, and the power supply potential is output to the output O.

(3) OE and A are "H",
In case of "L" level: The outputs of the gate circuits 9a and 9b are "L" and "H", respectively.
The level becomes FET1, the FET1 is off, and the FET2 is on. Since the operation when the FET1 is in the off state is the same as that in the case of (1), the FETs 1, 2 and 3 are "off",
The ground potential is output to the output O in the "on" and "off" states. FIG. 4 is a diagram for explaining a truth value that summarizes the results of the above operations.

Next, the operation of the control unit 3 will be described with reference to the time chart shown in FIG. P1 to P5 and A1 to A in the figure
6, OE1 to OE6 represent the timings of the print timing signal, the output level control signal, and the output high-impedance control signal shown in FIG. 1, respectively, and 10 to 15 are the three-state output drive circuits shown in FIG. D1
The output timing of D6 is shown.

In this timing example, a total of three nozzles are driven, but in an actual nozzle, the optimum electric signal supply time may differ for each nozzle due to manufacturing variations and the like. In the timing example of FIG. 5, the respective electric signal supply start times are shifted based on this point. When the print timing signal P1 is first input at the timing T1, the control unit 3 changes the timing as shown in the figure. "L", which is 180 degrees out of phase with the output level control signals A1 and A2,
A waveform that repeats the "H" level is output, and the "H" level is output to the output high impedance control signals OE1 and OE2. Since the drive circuits D1 and D2 of the supply unit perform the operation indicated by the truth value in FIG. 4, the output level has a waveform that outputs the power supply potential and the ground potential with a phase difference of 180 degrees. Since the drive circuit D1 and the drive circuit D2 are out of phase with each other by 180 degrees, when the drive circuit D1 outputs the power supply potential and the drive circuit D2 outputs the ground potential, the drive circuit D1 moves from the drive circuit D2 to the ink resistor R1 in FIG. When the drive circuit D1 outputs the ground potential and the drive circuit D2 outputs the power supply potential, the current alternately flows from the drive circuit D2 to the drive circuit D1. No current flows to the ink resistors R3 to R5 because the outputs of the drive circuits D3 to D6 are in a high impedance state.

When the print timing signal P5 is input at the timing indicated by T2, the drive circuits D5 and D6 as well as the drive circuits D1 and D2 operate in the same manner to supply current to the ink resistor R5. At this time, the control unit 3 always controls the output level of the drive circuit D5 to the same potential as that of the drive circuit D2 as shown in the figure, so that unnecessary current is generated between the drive circuits D2 and D5 through the ink resistors R2, R3, and R4. I try not to flow.

Next, when the print timing signal P3 is input at the timing T3 and the drive circuits D3 and D4 start energizing the ink resistor R3, the control section 3 causes the ink resistors R2 and R4 to generate an unnecessary current. In order to prevent the flow, the output levels of the drive circuits D2 and D3 and the drive circuits D4 and D5 are controlled to the same potential. However, if simply controlled, as shown in the period of T5 in FIG. 6, the drive circuits D5 to D6 are
Since a current flows in the same direction through the ink resistance R5 for twice as long as a normal time, there arises a problem that it causes deterioration of the electrode due to electrolysis. Therefore, in the present embodiment, the switching frequency of the output levels of the drive circuits D1 to D6 is temporarily set to double the frequency of the normal cycle only as shown in the period T4 of FIG. This problem was solved by adjusting the phase of the output signal of the circuit.

FIG. 7 is a block diagram of an example of the control unit 3 for performing such control. Reference numeral 16 is a phase control unit for controlling the phases of the output level control signals A1 to A6, 17 is an OE control unit for controlling the output high impedance control signals OE1 to OE6, and 18 is an output level control signal A1 to A6.
Determination unit that determines the condition for doubling the switching frequency of the print timing signals P1 to P4 and outputs the determination signal J,
Reference numeral 19 is an oscillator for generating a reference clock signal CLK having a frequency twice the switching frequency of the output level control signals A1 to A6, 20 to 25 are selectors, and 27 is a CLK signal ½.
Is a frequency divider for generating a frequency-divided clock signal HFCLK, 28 is a selector for selecting either the reference clock signal CLK or the frequency-divided clock signal HFCLK, and 26 is a PLS signal output from the selector 28. Inverting inverter gate circuits, and 29 to 34 are AND gate circuits. The selectors 20 to 25 select either the PLS signal output from the selector 28 or the nPLS signal output from the inverter gate circuit 26, and the outputs from the selectors 20 to 25 are AND gate circuits 29 to 3.
4 inputs.

The phase controller 16 controls the print timing signal P1.
Each time ~ P5 is input, the states of the phase selection signals S1 to S6 are changed and output. The phase selection signals S1 to S6 are connected to the selection control inputs of the selectors 20 to 25. The selectors 20 to 25 invert the PLS signal output from the selector 28 or the PLS signal by the inverter gate circuit 26 to change the phase. Either of the nPLS signals that are shifted by 180 degrees is selected. The OE controller 17 also outputs the output high impedance control signals OE1 to OE6. The AND gate circuits 29 to 34 are supplied with the outputs of the selectors 20 to 25 and the output of the OE controller 17, and output the output level control signals A1 to A6 shown in FIG. For example, in the period up to T1 in FIG. 5, the OE control unit 17 outputs the high impedance control signal OE1.
To OE6 are all held at "L" level, only the OE1 and OE2 are set to "H" level after inputting the print timing signal P1 at T1, and at the same time, the phase control unit 16 sets S1, S3 to S6 after inputting the print timing signal P1. "L" level,
By setting S2 to "H" level, desired output level control signals A1 to A6 and high impedance control signals OE1 to OE6 can be obtained.

The judgment section 18 is provided with print timing signals P1 to P
It is determined whether the CLK signal is selected and output as the PLS signal for each state change of No. 4, and when it is output, the determination signal J is output for a period of two cycles of the CLK signal. Selector 2
Reference numeral 8 selects and outputs the HFCLK signal while the determination signal J is not input, and selects and outputs the CLK signal while the determination signal J is input. For example, if the print timing signal P3 is input at the timing of T3 in FIG.
Outputs the determination signal J, and outputs the CLK signal as the PLS signal for one cycle of the HFCLK signal. After that, the phase control unit 16 sets S1 to S6 to "L", "H",
“H”, “H”, “H”, “L” level to “L”,
The level is changed to "H", "H", "L", "L", "H" level, and the OE controller 17 sets OE1 to OE6 to "H",
By changing from "H", "L", "L", "H", "H" level to "H", "H", "H", "H", "H", "H" level Desired output level control signal A
1 to A6 and high impedance control signals OE1 to
OE6 can be obtained.

In this embodiment, the timing of starting the supply of the electric signal has been described, but the same control is performed at the timing of ending the supply.

[0021]

As described above, according to the present invention, the ink resistance conducting electrode is commonly used between the adjacent ink flow passages, whereby the distance between the ink flow passages in the multi-nozzle head is shortened and a compact electricity supply system is provided. Inkjet printer head can be realized, a signal applied to the ink energizing electrode is an AC voltage, and a circuit that can output high impedance is used for the drive circuit that applies the voltage to the electrode, and the phase of the drive circuit output is used. Is controlled, and when the voltage application time to the electrodes is made independent for each nozzle, the frequency of the applied AC voltage is doubled each time the application is started to prevent a DC current from flowing between the electrodes, resulting in a long life. We have made it possible to implement an energized inkjet printer.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an ink discharge recording apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional perspective view showing an ink ejection portion in the ink ejection recording apparatus according to the embodiment of the present invention.

FIG. 3 is a drive circuit diagram which constitutes a supply unit in the ink discharge recording apparatus of one embodiment of the present invention.

FIG. 4 is a diagram illustrating a truth value indicating a relationship between an input and an output of a drive circuit that constitutes a supply unit in the ink ejection recording apparatus according to the embodiment of the present invention.

FIG. 5 is a diagram showing a control timing of a control unit in the ink ejection recording apparatus according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a defective state of control timing of a control unit in the ink ejection recording apparatus according to the embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a control unit in the ink discharge recording apparatus according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view of a conventional ink ejection unit.

[Explanation of symbols]

1 Discharge part 2 Supply part 3 Control part 4a, 4b, 4c Liquid path wall 5a, 5b, 5c Electrode 6a, 6b, 6c Nozzle hole 7a, 7b, 7c Liquid path 9a, 9b Output timing of gate circuit 10 D1 11 D2 of Output timing 12 Output timing of D3 13 Output timing of D4 14 Output timing of D5 15 Output timing of D6 16 Phase control section 17 OE control section 18 Judgment section 19 Oscillator 20-25, 28 Selector 26 Inverter gate circuit 27 Divider 29 to 34 AND gate circuit D1 to D6 drive circuits OE, OE1 to OE6 output high impedance control signal A, A1 to A6 output level control signal O electrical signal output P1 to P5 print timing supplied to the ejection unit Signal CLK Reference clock signal HFCLK Divided clock signal J judgment signal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoji Oyama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A nozzle row composed of nozzles for ejecting ink, a liquid passage communicating with each nozzle of the nozzle row, and a nozzle provided on both sides of the liquid passage and common to adjacent nozzles. A pair of electrodes, a supply means for supplying an electric signal to the electrodes, and a thermal energy capable of forming flying droplets by controlling the supply means so as to supply an alternating current to the ink to generate the thermal energy. When the supply unit that supplies the electrical signal to the electrode of the nozzle in the nozzle row supplies the electrical signal at different timings, the electrical signal is supplied to each electrode. An ink ejection recording apparatus characterized in that control is performed to double the frequency of an electric signal being supplied at a timing of start and end of supply for a fixed period of time.