JPH05338240A - Controlling device for electrification in recorder - Google Patents

Abstract

PURPOSE:To optimize recording energy at a time of printing in a controlling device for electrification in a recorder by temporarily connecting specified resistance instead of a thermistor prior to recording actuation of the recorder, measuring pulse width sent from a pulse generation circuit, calculating dispersion of a temperature detection system and performing correction of the result of measured temperature on the basis thereof. CONSTITUTION:Dispersion of a temperature detection circuit 4 for detecting the temperature of a thermal head 2 is calculated. Controlling voltage Vcont applied to a pulse generation circuit 1 is regulated and set on the basis thereof. Therefore, the temperature of the thermal head 2 can accurately detected without receiving effect based on dispersion of the temperature detection circuit 4. A proper printing strobe pulse can be given in accordance therewith and recording energy at a time of printing is optimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energization control device for a printing thermal head used in a recording device such as a facsimile.

[0002]

2. Description of the Related Art Conventionally, a printing thermal head in a recording apparatus of this type is energized by controlling the width of a drive pulse (referred to as a printing strobe pulse) applied to the head, thereby adjusting the density of printing. It is supposed to be done. This print strobe pulse is generated by the timer I.
It is output from a pulse generation circuit using C or the like, but in order to control the heat generation amount so that the thermal head reaches a set temperature, it must be controlled to have an appropriate pulse width according to the temperature of the thermal head. Therefore, it is known that the temperature of the thermal head is detected by a temperature detection circuit having a sensor such as a thermistor, and the print strobe pulse width is controlled according to the detected temperature.

[0003]

However, in the conventional device, when the temperature is detected by the temperature detection circuit, variations in the temperature detection circuit system including the thermistor and fluctuations in the power supply voltage of the temperature detection circuit cause a pulse. The output pulse width of the generation circuit is affected, and as a result, the printing energy may not be properly optimized. The present invention is to solve the above-mentioned problems, and in the energization control device of the recording device, a predetermined resistance is temporarily connected in place of the thermistor before the recording operation of the device, and the pulse width from the pulse generating circuit is The purpose is to optimize the recording energy at the time of printing by measuring the variation of the temperature detection system and correcting the temperature measurement result based on the variation.

[0004]

In order to achieve the above object, the present invention provides a pulse generating circuit for outputting a print strobe pulse, a thermal head for generating heat according to the pulse width to perform printing, and the thermal head. And a temperature detection circuit including a temperature sensor for detecting the temperature of the pulse generation circuit, the pulse width output from the pulse generation circuit based on a control voltage applied to the pulse generation circuit and a voltage obtained from the temperature detection circuit. In the energization control device of the recording device to control,
Prior to the recording operation of the apparatus, circuit switching means for temporarily connecting to the temperature sensor in place of the temperature sensor, and measuring the pulse width output from the pulse generating circuit when switching to the predetermined resistance side, By comparing this with a predetermined value obtained in advance, a means for detecting the variation in the circuit of the temperature detection system and the pulse width output from the pulse generation circuit when switching to the temperature sensor side are detected as described above. The temperature conversion value is obtained from the pulse width in consideration of the circuit variation and the means for setting the control voltage applied to the pulse generating circuit based on the circuit variation and the temperature conversion value detected above is provided. ..

[0005]

In the above structure, the pulse width output from the pulse generation circuit and applied to the thermal head is the control voltage and the temperature dependent voltage obtained from the temperature detection circuit including the temperature sensor for detecting the temperature of the thermal head. However, before the recording operation of the device, temporarily connect the temperature sensor to the specified resistance and measure the output pulse width from the pulse generation circuit in this state. By comparing with a predetermined value, the variation of the circuit of the temperature detection system is detected. Further, the temperature conversion value is obtained from the pulse width output from the pulse generation circuit when switching to the temperature sensor side, taking into account the circuit variation detected above. Further, the control voltage applied to the pulse generation circuit is set based on the circuit variation and the temperature conversion value detected above. This makes it possible to correct an error due to variations in the temperature detection system circuit, and to apply an appropriate output pulse to the thermal head.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An energization control device for a recording device in a facsimile machine according to an embodiment of the present invention will be described with reference to FIG. The pulse generation circuit 1 is composed of a timer IC composed of a monostable multivibrator, and outputs a print strobe pulse to an output terminal OUT. The output pulse is given to a gate array (not shown) to control heat generation due to energization of the printing thermal head 2. This output pulse needs to be controlled to have an appropriate pulse width according to the temperature of the thermal head 2. In the pulse generation circuit 1, a trigger pulse is input from the gate array to the trigger terminal Tri, a clear pulse is input to the reset terminal RES, a control voltage Vcont is input to the control terminal CONT, and the terminal DIS is obtained by a temperature detection circuit described later. The voltage Vd is input. The thermistor 3 is a temperature sensor that detects the temperature of the thermal head 2. The thermistor 3 is connected in series with the resistor R4 and the capacitor C to form a charging circuit, and thus forms the temperature detecting circuit 4. The output pulse rises by the trigger pulse, the capacitor C of the charging circuit is charged by the trigger pulse, and the charging time changes depending on the temperature of the thermistor 3. Then, the output pulse falls when the control voltage Vcont and the voltage Vd become equal.

A resistor R provided in parallel with the thermistor 3.
3 is a temporary analog switch ASW2 when the power is turned on.
This is a reference resistance corresponding to the resistance value at 25 ° C. of the thermistor 3 for measuring the variation of the thermistor 3, which is connected in place of the thermistor 3 by switching (circuit switching means). This temperature detection circuit 4 switches the device power supply + 24V to the resistance R by switching the analog switch ASW1.
It is connected to a power source (+ 5V) divided by 1 and R2 or a constant voltage power source + 5V. The voltage at the connection point between the resistor R4 and the capacitor C is the temperature detection voltage Vd. A CPU (not shown) that controls the entire apparatus reads the pulse width output from the pulse generation circuit 1 by software, and controls the voltage Vc via the D / A converter.
Output ont. The output pulse width output from the pulse generation circuit 1 is determined based on the control voltage Vcont and the voltage Vd obtained from the temperature detection circuit 4.

By the way, in order to generate an appropriate print strobe pulse according to the temperature of the thermal head 2,
It is necessary to improve the accuracy of temperature measurement of the thermal head 2 and to suppress fluctuations in the pulse width due to variations in the circuit constants of the temperature detection circuit 4. (A) and (b) of FIG.
It is a flowchart showing a procedure therefor, which will be described below. First, variations in circuit constants are detected when the power of the device is turned on (S1). Therefore, the analog switch ASW1 is temporarily set to the constant voltage + 5V side, and the analog switch ASW2 is set to the resistor R3 side. That is, the temperature detection circuit 4 is connected to a constant voltage power source, and a predetermined resistor R3 is connected instead of the thermistor 3. Then, the control voltage Vcont is set to a predetermined value, and a trigger pulse is given to the pulse generation circuit 1. The output pulse width at this time is measured by the CPU. The measured pulse width is compared with a previously known pulse width, and the variation of the circuit is detected from the deviation. The detected variation of the circuit is stored in the storage means (S2).

Next, during the recording operation, the temperature of the thermal head 2 is detected, for example, at the beginning of each page (S3).
Therefore, the analog switch ASW1 is set to a constant voltage + 5V.
, The analog switch ASW2 is switched to the thermistor 3 side. That is, the temperature detection circuit 4 is connected to the constant voltage power source and the thermistor 3 is connected. And
The control voltage Vcont is set to a predetermined value, and a trigger pulse is given to the pulse generation circuit 1. The output pulse width at this time is measured by the CPU. The actual pulse width is obtained by calculation by adding (subtracting) the variation of the circuit known above to the output pulse width. The deducted pulse width is converted into a temperature by referring to a temperature-pulse width table previously calculated.

Further, the control voltage Vcont for suppressing the fluctuation of the pulse width is obtained from the variation of the circuit constants detected above and the temperature conversion value (S4). That is, since the circuit variation is known from the above measurement, the value of the control voltage Vcont is calculated beforehand so as to correct it, that is, the pulse width becomes a predetermined value. Set based on the table. As described above, the temperature of the thermal head 2 can be accurately measured, and a predetermined appropriate print strobe pulse can be generated based on the result. Also, during normal recording, the analog switch ASW1
Is switched to the + 5V side where + 24V is divided by resistors R1 and R2. Thereby, the voltage fluctuation of + 24V can be automatically feedback-controlled to the output pulse width. In the above embodiment, the fluctuation of the power supply voltage of + 24V and the variation of the temperature detection circuit 4 are shown. However, at least the variation of the temperature detection circuit 4 can be corrected. Good.

[0011]

As described above, according to the present invention, the variation of the circuit of the temperature detecting system for detecting the temperature of the thermal head is obtained, and the control voltage applied to the pulse generating circuit is adjusted and set based on the variation. Therefore, the temperature of the thermal head can be accurately detected without being affected by the variations in the temperature detection system circuit, and an appropriate print strobe pulse can be applied in response to this, which optimizes the recording energy during printing. Can be promoted.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an energization control device for a recording apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation procedure of the device.

[Explanation of symbols]

 1 pulse generation circuit 2 thermal head 3 thermistor 4 temperature detection circuit R3 resistance R4 resistance C capacitor ASW2 analog switch Vcont control voltage

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location 8804-2C B41J 29/00 U

Claims (1)

[Claims] 1. A pulse generation circuit that outputs a print strobe pulse, a thermal head that generates heat according to the pulse width to perform printing, and a temperature detection circuit that includes a temperature sensor that detects the temperature of the thermal head. In the energization control device of the recording device, the pulse width output from the pulse generation circuit is controlled based on the control voltage applied to the pulse generation circuit and the voltage obtained from the temperature detection circuit. Prior to this, the circuit switching means for temporarily connecting to the temperature sensor instead of the temperature sensor and the pulse width output from the pulse generating circuit when switching to the predetermined resistance side were measured and obtained in advance. By comparing with a predetermined value, the means for detecting the variation of the circuit of the temperature detection system, and the pulse generation circuit when switching to the temperature sensor side Calculate the temperature conversion value from the pulse width that adds the variation of the circuit detected above to the output pulse width, and set the control voltage to be applied to the pulse generation circuit based on the variation of the circuit detected above and the temperature conversion value. An energization control device for a recording apparatus, comprising: