JPH045058A - Driver of impact head - Google Patents

Abstract

PURPOSE:To remove printing stop operation of an excess length by detecting directly accurately temperature of a solenoid without using a temperature detecting element by a method wherein the temperature of the solenoid is calculated from a reference voltage value for detection of a resistance value, a reference resistance value, and a voltage value at one end of the solenoid. CONSTITUTION:Temperature of a solenoid is calculated where collector emitter saturation voltage is taken as VQ2, regular direction voltage of a diode is taken as VD1, a resistance value of a solenoid 3 at temperature TO is taken as RO, and a temperature coefficient of a resistance rate of a solenoid element is taken as (a). When the resistance value of the solenoid 3 in measurement of Vt in voltage is taken as RL, the resistance value RL is expressed by the formula (1). When the resistance value of the solenoid 3 is taken as RL, temperature of the solenoid 3 is expressed by the formula (2). That is, temperature T of the solenoid 3 in measurement of voltage Vt is expressed by the formula (3). A microprocessor 11 calculates temperature T of the solenoid 3 by substituting a value of voltage Vt at one end of the solenoid 3 outputted from an A/D convertor 21 for the formula (3), and stopping of printing and its reopening are executed according to temperature T of the solenoid 3 so that the solenoid 3 is used within a specified service temperature value.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an impact head driving device.

[Prior Art] A conventional impact head drive device disposes a temperature detection element near a head drive solenoid, and monitors the temperature of the solenoid using an output signal from a temperature detection circuit using the temperature detection element to maintain a specified temperature. We stopped and restarted printing by driving the solenoid below to prevent the solenoid from burning out.

[Problems to be Solved by the Invention] However, even if a temperature detection element is provided near the solenoid, the heat generated by the solenoid is dissipated, conducted, and stored in places other than the temperature detection element, so it is difficult to accurately measure the temperature of the solenoid. Unable to detect. As a result, the printing operation may be stopped while the solenoid's detected temperature is much lower than the specified operating temperature, or the solenoid's detected temperature may drop to a value much lower than the temperature at which printing can be restarted after printing has stopped. This has the problem that printing is stopped for an excessively long time in order to prevent burnout, such as restarting the printing operation for the first time, and the printing speed is unnecessarily reduced.

Further, it is necessary to provide a space in the head for arranging the temperature detecting element near the solenoid, which not only disadvantages the dissipation of heat generated by the solenoid but also creates problems in that mounting the element takes time.

Therefore, the present invention aims to solve these problems.
The purpose is to provide an impact head drive device that does not reduce unnecessary printing speed by accurately detecting the solenoid coil temperature without using a temperature detection element.

[Means to solve the problem]

The impact head driving device of the present invention has means for outputting a reference voltage for resistance value detection that is lower than the driving voltage applied to the solenoid that drives the wire of the impact head,
A unidirectional conduction element that connects a switching element in series to both ends of the solenoid, and applies a reference resistance and a reference voltage power supply for resistance value detection between one end of the solenoid and the power supply line for the reference voltage for resistance value detection. The solenoid is connected in series and has a control means for stopping and restarting printing in response to an output signal output from the means for detecting the voltage at one end of the solenoid.

[Function 1] According to the configuration of the present invention, the temperature of the solenoid can be calculated from the reference voltage value for resistance value detection, the reference resistance value, and the voltage value at one end of the solenoid, so the temperature of the solenoid can be calculated directly without using a temperature detection element. It is possible to provide an impact head drive device that can accurately detect pressure, eliminates an excessively long printing stop operation, and does not cause unnecessary reduction in printing speed.

[Embodiment] FIG. 1 is a block diagram showing one embodiment of the device of the present invention.
A diode is used as a unidirectional conducting element.

The microprocessor 11 controls the entire operation of the impact head driving device based on programs and the contents of the ROM 12 that stores various data, while storing and referring to operational control data programmed in the RAM 13.

Reference numeral 4 in the figure is a circuit block that outputs solenoid drive timing signals P1 and P2 that become H level at the timing of printing.

FIG. 2 shows an example of the circuit configuration of the voltage detection means 2 shown in FIG. 1, which is composed of an A/D converter 21 and a latch 22.

The microprocessor 11 outputs control data to the solenoid drive timing signal output circuit block 4 via the data bus 14 so as to output the Pl and P2 signals when executing a printing operation.

When the microprocessor 11 is not executing a printing operation, the voltage detection means 2 outputs a voltage detection timing signal P3.
After outputting data to the latch 22 via the data bus 14 and inputting the voltage value at one end of the solenoid output from the A/D converter 21, the detection timing signal P3 is output.
The latch 2 is connected via the data bus 14 so that the output of
Output the data to 2.

When the voltage detection timing signal P3 is output, the switching element Qll is off, and the P3 signal causes the switching element Qll to be turned off.
The reference voltage Vref for resistance value detection is low enough not to turn on the wire and drive the wire.
It is applied to the solenoid 3 via f.

The collector-emitter saturation voltage of transistor Q2 is VQ2
, the forward voltage of the diode is VDI, the resistance value of the solenoid 3 at temperature TO is RO, the temperature coefficient of resistivity of the solenoid element is α, and the solenoid temperature is calculated as follows. Incidentally, since the values of the above data can be known in advance, they are stored in the ROM 12.

Letting RL be the resistance value of the solenoid 3 when measuring the voltage Vt, the resistance value RL is expressed by equation (1).

If the resistance value of the solenoid 3 is RL, the temperature of the solenoid 3 is expressed by equation (2).

That is, if the temperature of the solenoid 3 when measuring the voltage Vt is the temperature T of the solenoid 3 when measuring the voltage Vt, T is expressed by equation (3).

It is expressed by formula (4).

The microprocessor 11 calculates the temperature T of the solenoid 3 by substituting the value of the voltage Vt at one end of the solenoid 3 output by the A/D converter 21 into equation (3), and controls the solenoid 3 within the specified temperature value. Printing is stopped and restarted in accordance with the temperature T of the solenoid 3 to be used.

FIG. 3 is a block diagram showing another embodiment of the device of the invention, using a transistor as the unidirectional conduction element.

When the voltage detection timing signal P3 is output, the switching element Qll is off, and the P3 signal causes the switching element Qll to be turned off.
2. A low resistance value detection reference voltage Vref that does not turn on Q31 and drive the wire is immediately applied to the solenoid 3 via the transistor Q31 and the reference resistor Rref. The collector-emitter saturation voltage of transistor Q31 is VQ3.
1 and Equation (4) The microprocessor 11 calculates the temperature T of the solenoid 3 by substituting the value of the voltage Vt at one end of the solenoid 3 outputted by the A/D converter 21 into the equation (3). Temperature T of solenoid 3 is adjusted so that it is used within the specified temperature value.
Printing is stopped and restarted accordingly.

[Effects of the Invention] As described above, according to the present invention, the temperature of the solenoid can be calculated from the reference voltage value for resistance value detection, the reference resistance value, and the voltage value at one end of the solenoid, without using a temperature detection element. The temperature of the solenoid can be directly and accurately detected, there is no need to stop printing for too long, so there is no unnecessary drop in printing speed, and since no temperature sensing element is mounted, good head heat dissipation measures can be taken. Therefore, it becomes possible to provide an impact head drive device that is designed with a high degree of accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the apparatus of the present invention. FIG. 2 is a circuit diagram of the voltage detection means shown in FIG. 1. FIG. 3 is a block diagram showing another embodiment of the apparatus of the present invention. Qll, Q12. Q2. Q31. Q3
2.Transistor DI...Giode Pl, P2...Solenoid drive timing signal P3...
...Voltage detection timing signal or higher 3 ・ 4 ・ V 1 ・ ・ ・ Vref ・ Vt ・ ・ ・ Rref ・ ・Microprocessor・ROM・RAM・Data bus・Voltage detection means・Solenoid・Solenoid drive timing signal Pressure circuit block・For head drive'r! 1 source, reference voltage for resistance value detection 1 source, solenoid terminal voltage, reference resistance Applicant: Seiko Epson Co., Ltd. Representative Patent attorney: Kizobe Suzuki (1 other person) Figure 1 Figure 2

Claims (1)

[Scope of Claims] The present invention includes means for outputting a reference voltage for resistance value detection lower than a drive voltage applied to a solenoid that drives the wire of the impact head, a switching element is connected in series to both ends of the solenoid, and the A unidirectional conduction element for applying a reference resistance and a reference voltage power source for resistance value detection is connected in series between one end of the solenoid and a power line for the reference voltage for resistance value detection, and the voltage at one end of the solenoid is detected. An impact head driving device comprising: a control means for stopping and restarting printing in response to an output signal output by the means for driving the impact head.