JPS58179669A - Method and apparatus for heat-sensitive recording - Google Patents

Abstract

PURPOSE:To perform recording of printing quality with very high stability by instable power soruces by a method in which the output of a temperature simulation circuit provided is compared with voltage and thereby the heating time of a thermal head is controlled. CONSTITUTION:A temperature simulation circuit, a comparision circuit compare the output of the temperature simulation circuit and a given voltage, and an accumulator to induce a signal that the output of the simulation circuit reaches given voltage are provided. For a thermal head, a recording mediu, and/or an ink sheet, after the time when the head, obtained from the heat capacity and heat resistance, reaches a given temperature, electric signal for heating the head is discontinued. Further, what total heat amount applied of the head reaches a given heat amount is calculated, the heating of the head is stopped, and pictures are recorded on the recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a thermal head that contacts a recording medium such as recording paper or thermal paper directly or via an ink sheet, and heats the thermal head based on an electric signal. The present invention relates to a thermal recording method and apparatus for recording an image or the like on the recording medium.

An example of this type of thermal recording method and its device is shown in Figs.
This will be explained according to FIG.

In the thermal recording apparatus 1 of the thermal transfer type shown in FIG. Built-in.

The recording paper 3 is stored in a folded state in a cassette 4, for example, and is sent to a thermal transfer section 6 via a roller 5. After being transferred, the paper is discharged out of the apparatus as shown by arrow A.

The substrate film 11 is sent from the supply roll 12 to the thermal transfer section 6 via the guide roller 13 and the drive roller 14.
Furthermore, it is wound up from the driving roller 15 to the winding roller 16. Note that the substrate film 11 is, for example, a supply roll 1
2 and the guide roller 13, a heat-melting ink (not shown) is applied thereto.

A photosensor (for example, an infrared light sensor) 17 for detecting the substrate film 11 coated with heat-melting ink is disposed in front of the drive roller 14 on the movement path of the substrate film 11 . Further, for detecting the recording paper 4, a seven sensor (for example, an infrared light sensor) 19 is arranged in front of the pressure roller 18.

The thermal transfer section 6 is provided with a set of a thermal (line) head and a platen roller 21.

Further, pressure rollers 18,n for sandwiching the recording paper and the substrate film 11 between the driving rollers 14 and 15 are arranged before and after the rollers. Note that arrow B in the drawings indicates that a pressure contact drive mechanism is provided.

Further, according to the thermal direct transfer type apparatus IA shown in FIG.
It is fed out from the printer, is sandwiched between the throat 2OA and the platen roller 7A into a thermal line (line), and is selectively colored by heating by the head 2OA. Then, this thermal paper is discharged from the transport rollers 5A and 6 with the image recorded as a color pattern.

Incidentally, although the external appearance of the thermal head is as shown in FIG. 2, its main parts are constructed as shown in FIG. 3. That is, it has a thermal insulating layer 26 on a ceramic substrate 25 [7], on which a heating element layer 27, a large number of counter electrodes and 4 are laminated, and is further covered with a surface protection layer (not shown). .

In addition, 30 and 31 shown in FIG. 2 are printed circuit boards,
A counter electrode array and four external connection terminals are formed on these. The above-mentioned head structure is conventionally known, and a predetermined pulse voltage (applied pulse) is supplied between the opposing electrode rows 29, whereby the heat generating layer 27 selectively generates heat at the opposing electrode rows 4. become.

In order to perform thermal recording at high speed, the counter electrode 5
2B and 29 all at once or selectively with an applied pulse to obtain heat from the heat generating layer n and record it on the recording paper 3. At this time, if the size of the recording paper 3 is, for example, B4 size and the thermal head addition is 8 dat/mm,
2048 dat counter electrodes 28,29 are required. And for the above heat generation, approximately 0.6 W per 1 dOt~
A power of about IW is required, and even if recording is performed twice, a power supply capacity of 600W to IKW is required.

Moreover, the front distribution power supply requires a stabilized power supply, and even if a switching regulator is used, it is quite expensive.

The present invention corrects the above-mentioned defects and provides a thermal recording method and apparatus capable of recording extremely stable print quality even with an unstable power source.

That is, in the method according to the present invention, a thermal head is brought into contact with a recording medium directly or via an ink sheet, and the thermal head is heated (7) based on an electric signal, thereby recording an image or the like on the recording medium. In the thermal recording method, the thermal head is determined based on a curve corresponding to a temperature rise of the thermal head obtained from at least the heat capacity and thermal resistance of at least one of the thermal head, the recording medium, and the ink sheet. After the predetermined temperature is reached, the electrical signal for heating the thermal head is intermittent, and furthermore, when it is calculated that the heating dose applied to the thermal head has reached a predetermined amount of heat, the heating of the thermal head is stopped. It is characterized by this.

However, the device according to the present invention includes the temperature simulation circuit formed by the thermal spacing, a comparison circuit that compares the output of the simulation circuit with a predetermined voltage, and derives a signal when the output of the simulation circuit reaches a predetermined power. It is characterized by comprising an accumulator.

An embodiment of the present invention will be described below with reference to the drawings.
Prior to this, the process of arriving at the technical idea of the present invention will be described.

That is, conventionally, in order to perform stable thermosensitive recording, a constant voltage power source is used, and a constant pulse voltage (Figure 4B) is applied between the opposing electrodes to obtain a constant peak temperature (Figure 4B). Figure A) was obtained and recorded using this. Figure 4 (4
) can generally be expressed by an equivalent circuit in an electrical circuit. If the temperature is θ (℃), the heat leakage resistance is R ('C/W), the heat capacity is C (J/℃), the applied power is q (W), and the amount of heat is Q (J), then the temperature rise is 1
If = 0 and Q = 0, then θ-Rq (1-00R) -------------------------------------
...It is expressed as (1).

On the other hand, when the temperature decreases, θ0 (℃) at 1=00
If so, =1 θ−θ0・ecR・・・・・・・・・・・・・・・・
It is expressed as (2).

Here, looking at the relationship between applied voltage and temperature, if the applied voltage (or power) becomes higher, the pulse to reach the same temperature may be shorter, but the total amount of thermal energy will change.

Furthermore, if the amount of applied energy is kept constant, the print quality should be uniform and uniform, but if the applied voltage is too high, the peak temperature will depend on the thermal time constant (indicated by CR) at that time. In some cases, the temperature exceeds 1000°C. In such a state, distortions and cracks occur within the thermal head, and unexpected situations such as burnout of the heating element also occur. In any case, a change in the applied voltage appears as a change in the heating resistance value, which lengthens the life of the thermal head iztσ.

From the above-mentioned viewpoint, we have come up with a recording method and apparatus that can follow changes in applied voltage and perform stable thermosensitive recording even when using an unstabilized power source.

The specific method is described below.The thermal capacity and thermal resistance of the thermal head and the thermal capacity and thermal resistance (
In addition, for the thermal transfer type, the heat capacity and thermal resistance of the heat-melting ink film are calculated in advance. Then, an electric circuit is constructed of the combined heat capacity Cs and the combined thermal resistance R8 with capacitors and resistors (557° C. is μF and 1° C./W is Ω). Simulations are performed in real time using this electrical circuit.

If the applied voltage is high, the supply of the applied pulse is temporarily stopped when the electric circuit, or in other words, the simulation circuit, reaches a certain temperature θl. Thereafter, when the temperature of the simulation circuit reaches 02 (temperature slightly lower than θl), application pulses are supplied again until the temperature reaches θl. This operation is repeated, and when a predetermined total amount of applied energy is reached, the supply of applied pulses is stopped.

The above is the printing time of 1 dat.

The seamiresion circuit that operates as described above is basically achieved by a circuit configuration as shown in FIG. The specific circuit operation of the seamiresion circuit will be explained in more detail later with reference to FIG. 9, so an outline thereof will be described here.

An applied voltage V i n is supplied to the input terminal T1.

Capacitor C8 and resistor R8 correspond to CR shown in equations (1) and (2). The non-inverting input terminal of the voltage comparator 32 has a temperature θl shown in FIG. 6 (4) and FIG. 7 (4).
A voltage corresponding to is supplied. Further, a voltage corresponding to temperature 02 shown in FIG. 6 is supplied to the non-inverting input terminal of each voltage comparator. 6 shows the thermal response characteristics when the applied voltage Vin is high, and the applied pulse Vout as shown in FIG. 6) is obtained from the timing controller.

FIG. 7(4) shows the thermal response characteristics when the applied voltage Vin is low. Note that the temperature θl is, for example, about 300°C, and the temperature θ2 is, for example, about 280°C.

Then, from the output terminal T2 in Fig. 6) and Fig. 7 (b)
An applied pulse Vout as shown in is obtained and supplied to the thermal head. By the way, if the total amount of energy applied by the applied pulse Vout is E, this is determined by the product of the applied power W and the application time S.

In other words, E=W-8(J)・・・・・・・・・・・・・・・・・・
(3) If the resistance value of the heating element is RH and the applied voltage Vin is V, then the above equation (3) is E=V2//RH・5(J)...・・・・・・・・・・・・
(4) From this equation (4), it can be understood that in order to obtain a constant printing quality, it is sufficient to keep E constant.

Regarding equation (4), since l/RH is a constant, E can be made constant by changing S in response to fluctuations in V. In other words, even if the applied voltage Vin contains a ripple voltage after full-wave rectification and incomplete smoothing as shown in FIG. E can be kept constant.

Next, specific embodiments of the present invention will be described with reference to FIGS. 8 to 15.

An unstable applied voltage Vin containing a ripple component as shown in FIG. 8 is supplied to the input terminal 'hK. A pulse-like start signal v as shown in FIG. 10 (4) is connected to the terminal T3.
l is supplied. The start signal 1 is supplied to the set terminal of the flip-flop circuit (hereinafter referred to as FF) 36 via the OR circuit A in FIG. Therefore FF3
The voltage level of the output Q of 7 is as shown in ) in Fig. 10.
■Become the level. The voltage level of the output Q of the FF 36 also becomes H level as shown in FIG. 10(C).

Then, by using the Q output of FF36, analog
”The switch SWI is switched to the on state.
The analog switch SWl is illustrated as a mechanical structure for convenience of explanation. The multiplier Okara obtains a voltage v2 obtained by squaring the applied voltage Vin, and this voltage v2 is applied to the switch SWI.
to the line tl. The capacitor Cs and the resistor R8 constitute a thermal response simulation circuit as described above. The voltage ■2 on the line tl is the voltage comparator 3
2.33 non-inverting input terminals. Note that the voltage V2 obtained from the multiplier is divided into the resistance values of the variable resistor vR1 and the resistor Rt by a voltage controlled oscillator (hereinafter referred to as VCO), and is supplied to the non-inverting input terminal of the voltage comparator 33. .

When the voltage level on the line tl gradually rises and reaches the voltage Vfh as shown in FIG. (referred to as MM) 40 output signal becomes H level. Each of the input terminals a, b, and c of the AND circuit 41 becomes H level, and the output signal also becomes H level. The output signal of the AND circuit 41 is sent to the OR circuit 4.
2 to the reset terminal of FF 36, the Q output of FF 36 becomes L level.

Then, the analog switch SWI is turned off, and the voltage V2 on the line 11 gradually decreases.

When voltage v2 drops to voltage Vθ2, an output signal from the voltage comparator is obtained, and the output of MM43 becomes H level. Each input terminal aXbXc of the AND circuit 44 is set to H.
level, and the output signal also becomes H level. The output signal of the AND circuit 44 is supplied to the FF 36 set terminal via the OR circuit 35. The circuit operation described above is the circuit operation from time t1 to time t2 in FIG. 10.

Then, when the FF 36 is switched to the reset state again, the analog switch is turned on again, and the same circuit operation as from time to to time tx is performed. As a result, an applied pulse having a waveform as shown in FIG. 10C is outputted from the output terminal T2 and supplied to the thermal head 20.

By the way, while the above operation is being performed, voltage v2 is supplied to vC039. When voltage v2 increases, V
The output frequency of CO39 gradually shifts to a higher frequency.

Note that this frequency change is, for example, 500 KHz to 2
The output signal of the VCO 39, which only needs to change on the order of MHz, is
It is supplied to an energy counter (hereinafter referred to as a counter) 46 via an AND circuit 45. Since the output signal of the VCO 39 shifts to a high frequency signal corresponding to the voltage level of the voltage V2, the output time of the carry signal output from the argument unit 46 is accelerated accordingly.

While the energy count is being performed by the counter 46, the control operation from time t2 to time t3 is performed, and the control action from time t3 to time t4 is repeated. The time of applied energy is controlled by the frequency division ratio N of the counter 46 and the frequency of the output signal of the VCO 39, and when a predetermined energy is reached, a carry signal Vc is output as shown in FIG. 10. By the carry signal Vc, FF36.37
is switched to the reset state, and the analog switch SWl
is also switched to the off state. That is, the simulation circuit shown in FIG. 9 returns to the initial state after the decrease based on equation (2).

Incidentally, the voltage difference between the voltages ■θl and ■θ2 shown in FIG. 10(c) is arbitrarily adjusted by the variable resistor VR1.

Further, an oscillator may be provided in place of the multiplier 38 and the CO 39 described above, so that the above-mentioned equation (4) is satisfied.

Next, in the simulation circuit described above, the resistor Rs is configured to be 360Ω, the capacitor C8 is configured to be 0.66 μFD, and experimental data will be shown when the applied voltage Vin is varied. Figure 11 shows experimental data when the applied voltage Vin is 18V, the time width of the applied pulse shown in (4) in the figure is approximately 0.8 m sec, and the waveform on line tl is shown in the figure).
It appeared as shown in. Note that Vθ1 is 320°C.

Figure 12 shows experimental data when the applied voltage Vin is 19V, and the distance between to and t1 is approximately 0.6 m5ec, and tz to t
s interval is approximately 0.1 m5ec. In addition, ■θl is 320
℃, Vθ2 is 280°C.

Figure 13 shows experimental data when the applied voltage ■in is 20V, and the distance between to = t1 is approximately 0.5 m see Xtz
- t3 is approximately 0.09 msec.

FIG. 14 shows experimental data when the applied voltage Vin was 22V.

FIG. 15 shows experimental data when the applied voltage Vin was 24V.

As described above, the present invention includes a temperature simulation circuit, and controls the heating time of the scissor head by comparing the output of this seamiresion circuit with a predetermined voltage. Therefore, even if the power supply voltage for heating the thermal head fluctuates, the thermal head will not become abnormally heated.

Therefore, the quality of printing on the recording paper is improved, and the thermal head is not burned out.

[Brief explanation of drawings]

Figures 1 (a) and (b) are sectional views schematically showing two sides of the U thermal recording device, Figure 2 is a perspective view showing the shape of the thermal head, and Figure 3 is the structure of the thermal head. FIG. 4 is a temperature characteristic diagram showing the relationship between applied pulses and temperature; FIGS. 5 to 15 show an embodiment of the present invention; FIG. 5 is a simulation diagram. A circuit diagram showing the basic configuration of the circuit, Figure 6 is a characteristic diagram showing the relationship between applied pulses and temperature in a simulation circuit, Figure 7 is a characteristic diagram showing the relationship between applied pulses and temperature at low temperature, Fig. 8 is a waveform diagram of the power supply voltage, Fig. 9 is a circuit diagram of a thermal recording device to which the present invention is applied, Fig. 10 is a waveform diagram showing the operation of the same circuit as above, Figs. 11, 12, and 13. , FIG. 14, and FIG. 15 are characteristic diagrams showing the relationship between applied pulses and temperature when the power supply voltage is changed. In addition, in the symbols used in the drawings, Cs, Rs
...Capacitors and resistors composing the simulation circuit 32.33 ...Voltage comparator 35.42 ...OR circuit 36.37 ...Flip-flop Pull circuit 38...
・・・・・・・・・・・・Multiplier 39・・・・・・・
・・・・・・Voltage controlled oscillation circuit 40.43...
... Monostable multivibrator 41.44.45...
...AND circuit 46...
・It is a counter. Agent Patent Attorney Hiroshi Aisaka Figure 1 (a) Figure 1 (b) Figure 4 Figure 5 (2) Figure 10 Figure 13 Figure 14 Figure 15 (Voluntary) Procedural Amendment July 1988 10th, 1982 Patent Application No. 62984 2, Title of the invention: Thermal recording method and its device 3, Relationship with the case of the person making the amendment: Name of the patent applicant (name) (127) Konishiroku Photo Industry Co., Ltd. 4, Agent (1), delete "(e.g. infrared light sensor)" on page 4, line 6 of the statement tube. (2), ``Thermal direct transfer type'' on page 4, line 15 has been corrected to ``1 thermal direct type''. (3) "Non-inverting input terminal" in lines 15-16 and 17-18 on page 10 and line 12 on page 13 will be corrected to "inverting input terminal." (4) On page 14, line 13, "reset state" is corrected to "set state." (5) Among the drawings attached to the application, Figure 5 will be corrected as shown in the attached sheet. One or More One Figure 5 403

Claims (1)

[Claims] 1. A thermal head is brought into contact with a recording medium directly or via an ink sheet, and the thermal head is heated based on an electric signal, thereby recording an image, etc. on the recording medium. In the thermal recording method for recording, regarding at least one of the thermal head, the recording medium, and the ink sheet,
After the thermal head reaches a predetermined temperature based on a curve corresponding to the temperature rise of the thermal head obtained from at least its heat capacity and thermal resistance, the electrical signal for heating the thermal head is interrupted; A thermal recording method, comprising: calculating that the heating dose applied to the thermal head has reached a predetermined amount of heat, and then stopping the heating of the thermal head. 2. A temperature simulation circuit configured based on at least the heat capacity and thermal resistance of at least one of the ≠ mark head, the ink sheet, and the recording medium; 1. A thermal recording device comprising: a comparison circuit for comparison; and an accumulator for deriving a signal indicating that the output of the simulation circuit has reached a predetermined power. 3. The thermal recording device according to claim 2, wherein the temperature simulation circuit is provided so that at least one of the elements corresponding to the heat capacity or the heat resistance can be switched. 4. An unstable applied voltage is input to a multiplier, the output of the multiplier is input to a voltage controlled oscillator, and an input signal to the accumulator is obtained from the voltage controlled oscillator. The thermal recording device described in item 2 or 3. 5. The thermal recording device according to claim 2, wherein the temperature simulation circuit is constituted by a capacitor and a resistor.