JPH04275153A - Solenoid valve driving device for ink jet recording apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording apparatus, and more particularly to a control device for driving a solenoid valve used to control the circulation of liquids such as ink and solvent.

0002

2. Description of the Related Art Inkjet recording devices are widely used in various fields including the food industry and the pharmaceutical industry because they can print dates, serial numbers, etc. in the production process at high speed, non-conflict, and with high quality. Particularly in the industrial field, where high speed is required, charge-controlled inkjet recording devices are used. A predetermined pattern is printed on a product by regularly forming ink into particles, charging the ink particles, and electrically controlling deflection.

FIG. 2 shows an example of an ink circulation circuit of a charge control type ink jet recording apparatus. The device is divided into a main body part 1 and a nozzle head part 2, and ink is sent out from an ink bottle 12 in the direction of the arrow by a pump 3, passes through a filter 4, and is regulated to a constant pressure by a pressure regulating valve 5. rear,
It is sent to the nozzle head section 2. The pressure at this time is displayed on the pressure gauge 6. The ink sent to the nozzle head section 2 is switched by the solenoid valve 7 to be ejected from the nozzle 8 or not. The ink ejected from the nozzle 8 is made into particles and used for printing, but the ink particles not used for printing are captured from the gutter 9 and returned to the ink bottle 12 by the pump 3 for reuse. When this cycle is repeated, the solvent component in the ink components evaporates into the air and the physical properties of the ink change. To compensate for this, the solenoid valve 11 is periodically opened to drain the solvent from the solvent bottle 10. The ink is supplied to the ink bottle 12.

Control of such electromagnetic valves 7 and 11 is shown in FIG.
This is done using the control circuit shown in . Although the circuit of the main control section composed of a microprocessor and the like is not shown in the control circuit, the input/output section 40 receives the opening/closing control data of the solenoid valves 7 and 11 from the main control section, and each It is output as an operation signal corresponding to each of the solenoid valves 7 and 8. Each of the output operation signals is given to the solenoid valve driving IC 42 via the buffer IC 41, and a +2 signal suitable for driving (starting) the solenoid valves 7 and 11 is sent.
The drive voltage from the 4V power supply is intermittent. The diode 43 is for absorbing back electromotive force generated when the voltage applied to the solenoid valve is cut off.

The ink circulation circuit and control circuit described in FIGS. 2 and 4 have been used for a long time in charge control type inkjet recording apparatuses, and after that, the ink circulation circuit and control circuit explained in FIGS. Ink concentration control device that accurately grasps solvent components and automatically replenishes them (Japanese Patent Laid-Open No. 62-6
(Disclosed in Publication No. 0651), checking ink viscosity,
In response to requests for improvements such as automation of ink ejection and stop at the start and end of work, and automation of various tasks during equipment installation and maintenance, an inkjet recording device using an ink circulation circuit as shown in Figure 3 has been developed. Proposed.

The ink circulation circuit shown in FIG. 3 includes, in addition to ink containers 12a and 12b for circulating ink, a bottle 20 for replenishing ink, a container 30 for measuring ink viscosity, and a container 30 for circulating ink. a pump 3a for
3b, 21, solvent replenishment pump 3c, solenoid valves 7, 11, 23, 24, for realizing automation of various operations.
25, 26, 27, 28, and 29.

[0007]

[Problem to be solved by the invention] The current consumption of the solenoid valve used in the circulation circuit proposed here is about 170 mA, but in reality, a plurality of solenoid valves (for example, nine) are used. , the total current consumption is large (e.g. 1.5
A). This value is 36W in terms of power consumption,
A large amount of electric power is required just to drive the solenoid valve. In addition, the power consumption of the solenoid valve generates heat, which causes deterioration of the physical properties of the ink and reduces the reliability of the apparatus as a whole.

[0008] In order to solve these problems, a method can be considered in which the electromagnetic valve is driven at the rated voltage at the time of startup, and then the voltage is lowered to the voltage required to maintain the operating state of the valve.

FIG. 5 is a circuit diagram of a control device that realizes this. When starting the solenoid valve 23, the operation signal A of the input/output section 40 is set to H level, the operation signal B is set to L level, the transistor 44 and the solenoid valve driving IC 42 are turned on, and the solenoid valve 2 is activated.
After the electromagnetic valve 23 is activated, the operation signal A of the input/output section 40 is set to L level, and the transistor 44 is turned off. At this time, a voltage of approximately 10V, which is obtained by subtracting the forward voltage drop (approximately 2V) of the diode 45 from the +12V side power supply voltage, is applied to the solenoid valve 23.

However, this control circuit requires two operation signal output terminals for one solenoid valve, and when the number of solenoid valves is large, the LSI used for the input/output section becomes large, especially in one-chip When using a microcomputer, this becomes a problem because the input/output section is limited.

An object of the present application is to provide an inkjet recording apparatus that solves the above problems with a simple circuit configuration.

0012

[Means for Solving the Problems] The present invention provides a solenoid valve driving device for an inkjet recording device that controls voltage applied to a solenoid valve by an operation signal based on control data given from a main control unit. The feature is that a switching circuit is provided to delay-process one operation signal and switch the magnitude of the driving voltage of the solenoid valve to two stages: startup and steady state. Specifically, the switching circuit includes a capacitor. The operation signal is delayed by the charging time of the charging/discharging circuit, which is composed of a charging resistor with a large resistance value and a discharging resistor with a small resistance value, and a control signal that applies a large driving voltage to the solenoid valve is generated.

[0013]

[Operation] The long charging time for charging the capacitor through a large value resistance becomes the time for applying the rated voltage. After charging is complete, the voltage switches to the solenoid valve holding voltage. When the current valve is stopped, the capacitor is quickly discharged through a small-value resistor, and the discharge is completely completed by the time of the next start-up, so that the rated voltage application time can be secured when the next solenoid valve is started.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below using the control circuit diagram shown in FIG.

[0015] In the control circuit, illustration of a main control section composed of a microprocessor or the like is omitted. Input/output section 40
converts the opening/closing control data for each electromagnetic valve given from the main control unit into an operation signal corresponding to each electromagnetic valve. Figure 1
shows only the circuit related to the solenoid valve 23. Solenoid valve 2
An opening operation signal (L level) output from the input/output unit 40 to open the solenoid valve 3 is applied to the solenoid valve driving IC 42 via the buffer ICs 41 and 47, and a driving current for driving the solenoid valve 23 flows therethrough. At this time, capacitor C1 is +5V
It is charged by the current flowing from the power source through the resistor R1. As the charging of capacitor C1 progresses, buffer IC4
8's input voltage increases. While the input voltage of the buffer IC48 is at L level, the buffer I for driving the transistor is
Since the output of C49 is at the L level, the transistor 44 is on, and when the solenoid valve driving IC 42 is turned on, a driving voltage of 24V is applied to the solenoid valve 23. Buffer I
When the input voltage of C48 becomes H level or higher, the transistor 44 is turned off, and the holding voltage from the +12 power supply side is applied to the solenoid valve 23. The capacitance of the capacitor C1 is 2
2μF, and the resistance value of resistor R1 is 220KΩ, and if a CMOS type is used as the buffer IC48, 24
The application time of the rated voltage of V is approximately 5 seconds.

Next, in order to close the solenoid valve 23, when a closing operation signal (H level) is output from the input/output section 40,
Solenoid valve driving IC42 via buffer IC41, 42
The output becomes H level, and the solenoid valve 23 is deenergized. At this time, the charge accumulated in the capacitor C1 is transferred to the resistor R
discharged through 1. When the capacitor C1 is discharged, the input voltage of the buffer IC 48 rapidly decreases, and when it drops below the L level, the transistor 44 turns on, completing preparations for applying the rated voltage of 24V when the next electromagnetic valve is activated. do. The resistance value of the resistor R2 is 1KΩ.
If one is used, the discharge time will be about 0.02 seconds. The diode 43 is for absorbing the back electromotive force generated when the voltage applied to the solenoid valve 23 is cut off.
The diode 46 is for preventing charging current from flowing from the resistor R2 side when charging the capacitor C1, and the diode 45 is for preventing the +24V power supply voltage from being applied to the +12V power supply side.This embodiment The voltage applied from the +12V power supply to the solenoid valve to maintain its operation is about 10V.

According to the above embodiment, since the discharging time of the capacitor C1 is very short, 0.02 seconds, the capacitor charging time is shortened when the solenoid valve is opened, and the rated voltage of 24V is not sufficiently applied as the driving voltage. First, problems such as the solenoid valve not starting will not occur.

[0018]

According to the present invention, one operation signal for one solenoid valve is processed by a simple circuit such as a capacitor and a resistor to control the magnitude of the voltage applied to the solenoid valve. Power consumption by the solenoid valve can be reduced, and problems caused by heat generation due to power consumption can be easily solved.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram of a solenoid valve drive device of an inkjet recording apparatus according to the present invention.

FIG. 2 is an ink circulation circuit diagram of a charge-controlled inkjet recording device.

FIG. 3 is an ink circulation circuit diagram of an improved charge-controlled inkjet recording device.

FIG. 4 is a control circuit diagram of a conventional electromagnetic valve control device.

FIG. 5 is a control circuit diagram of the improved solenoid valve control device.

[Explanation of symbols]

1... Main body part, 2... Nozzle head part, 3, 3a, 3b, 3
c, 21...Pump, 7, 11, 23, 24, 25, 26
, 27, 28, 29... Solenoid valve, 40... Input/output section, 41...
Buffer IC, 42...Solenoid valve driving IC, 44...Transistor, C1...Capacitor, R1...Charging resistor, R2...
Discharge resistor.

Claims (4)

[Claims] Claims: 1. In a solenoid valve drive device for an inkjet recording device that controls voltage applied to a solenoid valve by an operation signal based on control data given from a main controller, one operation signal for a target solenoid valve is delayed. 1. An electromagnetic valve drive voltage switching device for an inkjet recording apparatus, characterized in that a switching circuit is provided for switching the magnitude of the drive voltage of the electromagnetic valve into two stages: startup and steady state. 2. The electromagnetic valve drive device for an ink jet recording apparatus according to claim 1, wherein the delay of the operation signal is performed by a charging/discharging circuit of a capacitor and a resistor. 3. The electromagnetic valve drive of an ink jet recording apparatus according to claim 2, wherein the resistance value of the resistor through which charging current flows when charging the capacitor is made larger than the resistance value of the resistor through which discharging current flows when discharging the capacitor. Device. 4. The electromagnetic valve drive device for an ink jet recording apparatus according to claim 2, wherein a resistor used for charging the capacitor and a resistor used for discharging the capacitor are separate.