JPS58179057A - Heat-sensitive recorder - Google Patents

Abstract

PURPOSE:To reproduce a half tone, by switching in plural steps the highest temperature of a thermal head and therefore controlling the recording density of an object to the recorded by heat. CONSTITUTION:The applying voltage Vin is supplied to an input terminal. This voltage is then supplied to the inverted inputs of voltage comparators 20 and 21 via an analog switch SW1 and then a time constant circuit that is decided by a capacitor CS and a resistance RS. Here both CS and RS are equal to simulations of the synthetic heat capacity and synthetic heat resistance of a thermal head. The fixed levels of voltage equivalent to temperatures theta1 and theta2 are applied to the non-inverted inputs of the comparators 20 and 21 and then compared with each other. When the voltage Vin is high, the supply of an applying pulse is once stopped at a time point of the temperature theta1. Then the applying pulse is supplied again at a time point of the temperature theta2 and this supply is continued until the temperature theta1. This operation is repeated until the total applied energy reaches a prescribed level. Then the supply of the applying pulse is stopped by turning off the switch SW1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides thermal recording in which a thermal head is brought into contact with a recording medium, the thermal head is heated based on an electric signal, and thereby an image or the like is recorded on the recording medium. Regarding equipment.

Some thermal (line) heads used in conventional thermal recording apparatuses have a structure as shown in FIG. The external appearance of the thermal head 1 is as shown in FIG. 1(a), but its main parts are constructed as shown in FIG. 1(b). That is, it has a structure in which a heat insulating layer 3 is provided on a ceramic substrate 2, a heating element layer 4, a large number of counter electrodes 5 and 6 are laminated thereon, and the layer is further covered with a surface preservation layer (not shown). . Note that reference numeral 10.11 shown in FIG. 1(a) is a printed circuit board, on which external connection terminals for the counter electrode 5.6 are formed. A thermal recording device 12 incorporating such a linear thermal head 1 is schematically shown in FIG. 2 only. According to this device, thermal paper 1 is placed inside the case.
4 is fed out from the supply roll 13 and thermal (line)
It is sandwiched between the head 1 and the platen roller 15, and is selectively colored by heating by the head 1. The thermal paper is then discharged from between the transport rollers 16 and 11 with the image recorded as a color pattern.

In the head structure described above, a predetermined pulse voltage (applied pulse) is supplied to the counter electrodes 5.6, whereby the heat generating layer 4 selectively generates heat at the counter electrodes 5.6. In order to perform thermal recording, the counter electrode 5.6
The application pulses are applied all at once or selectively to obtain heat from the heat generating layer 4, and thermal recording is performed on recording paper (thermal recording paper). At this time, if the size of the recording paper is, for example, B4 size, the thermal head 1 is 8d0t/f+T11.
If so, a counter electrode 5.6 of 2048 dat is required. Due to the exothermic generation, K is approximately 0.6 to 0.06 per l dot.
A power of about IW is required, and even if recording is performed twice, a power supply capacity of 600 W to IKW is required.

In addition, in order to keep the printing quality of the recording paper constant, 600
All power from W to IKW must be kept in a stable state. For this reason, a stabilized power supply device has been used in the past, but a device that stabilizes power such as 600W to IKW is extremely expensive.

Further, the heat-sensitive recording paper used as the recording paper is recorded in shading from white to black, as shown in FIG. 3, depending on the temperature at which it is heated. That is, when the heating temperature is high heat θa, the recording paper is recorded in black. When the heating temperature is lowered to θb, a medium color is recorded, and when the heating temperature is further lowered to θC, the recording becomes white. Temperature control such as θa, θb1θC, etc. has been performed by changing the applied power (applied pulse) or application time to the thermal head. However, with an unstable power source, the control must be performed in response to voltage fluctuations, making accurate control very difficult.

The present invention corrects the above-mentioned defects, and is designed to reproduce the color density of various intermediate tones without being affected by fluctuations in power supply voltage.

That is, the thermal recording apparatus according to the present invention includes a simulator 1 circuit constituted by a thermal head that heats a recording medium and/or at least a heat capacity and a thermal resistance of the recording medium, and an output of the simulation circuit at a predetermined voltage. It is equipped with a comparator circuit for comparison, and an accumulator for deriving a signal when the output of the simulation circuit reaches a predetermined voltage, and the maximum temperature setting of the thermal head can be switched in multiple stages, and by this switching, the temperature is reduced by heat. The present invention is characterized in that it is configured to control the recording density (for example, color density) of the recording medium to produce an intermediate recording density (for example, intermediate color density) on the recording medium. .

An embodiment of the present invention will be described below with reference to 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 stable voltage power supply is used, and a constant pulse voltage (FIG. 4B) is supplied to the counter electrode 5.6 to maintain a constant peak temperature (FIG. 4A).
), and this was used for recording on recording paper (heat-sensitive).Thermal response as shown in FIG. '
C), the heat leakage resistance is R('C/w), and the heat capacity is C(J
/C), applied power? (W), calorific tube Q (J), the temperature rise is: If l = Q and Q - 0, then Q - R) (Lee's example)... (1)
On the other hand, when i=Q when the temperature decreases, θ. (0
C), then θ=θ. ,e□・・・・・・・・・・・・・・・・・・
・Represented by (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.

However, if the amount of applied energy is kept constant, uniform printing quality should be obtained. If the applied voltage is too high, the peak temperature will exceed 1000°C depending on the thermal time constant (represented by CR) at that time. When this condition occurs, distortion and cracks occur within the Sumaru head,
Furthermore, unexpected situations such as burnout of the heating element may also occur. In any case, changes in the applied voltage appear as changes in the heating resistance value, which shortens the life of the thermal head. We have come up with a recording method and apparatus that can follow this change and perform stable thermosensitive recording even when a modified power source is used.

The specific method will be described below. In this embodiment, the heat capacity and heat resistance of the thermal head and the heat capacity and heat resistance of the recording paper are calculated in advance. Then, the electric circuit tube is constructed. Simulations are performed in real time using this electrical circuit.

If the applied voltage is too high, the supply of the applied pulse is temporarily stopped when the electric circuit, in other words, the shimmy range 17 circuit reaches a certain temperature θl. Thereafter, when the temperature of the radiation circuit reaches 02 (temperature slightly lower than θl), application pulses are supplied again until the temperature reaches 01. This movement of the tube 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 l dat.

The shimmy range control circuit which performs the circuit operation as described above is basically achieved by a circuit configuration as shown in FIG. The specific circuit operation of the deviation circuit will be explained in more detail later with reference to FIG. 9, so a summary thereof will be given here.

An applied voltage Vin is supplied to the input terminal TI. Capacitor Cs and resistance & are C shown in equations (1) and (2).
Corresponds to R. Voltage comparison Masuda's non-inverting input terminal has a 6th
A voltage corresponding to the temperature θl shown in Figure (A) is supplied.

In addition, the non-inverting input terminal of the voltage comparator 21 is connected to the
) is supplied with a voltage corresponding to the temperature θ8. FIG. 6(A) shows the thermal response characteristics when the applied voltage Vin is high, and the applied pulse Vout as shown in FIG. 6(B) is obtained from the timing controller n.

Therefore, by adjusting the voltages corresponding to the temperatures θl and θ2 stepwise with the same voltage difference, a thermal response as shown in FIG. 7 can be obtained. The temperatures θ^θb and θC shown in FIG.
These correspond to temperatures θa%% and θC shown in FIG. 3, respectively.

Therefore, by adjusting the voltages corresponding to the temperatures θ1 and θa stepwise with the same voltage difference, it is possible to control the halftones of the recording paper.

By the way, if the total amount of energy due to the applied pulse Voutl (is E), this is determined by the product of the applied power W and the applied time S. That is, E=W'・5(J) ......-・・・・・・
・(3) If the resistance value of the heating element is applied and the applied voltage Win is V, then the above equation (3) becomes E = V''/RH-S (J) ・Concave ・(4) From this equation (4) , it can be understood that in order to obtain a constant print quality, it is sufficient to keep E constant.

Regarding (4) 2, since 1/) (Jl is a constant, E can be kept constant by changing S in response to fluctuations in V. In other words, as shown in FIG. Even if the applied voltage Vin includes a ripple voltage that has been simply full-wave rectified and then incompletely smoothed, E can be kept constant while changing S in response to fluctuations in the voltage level.

Next, specific embodiments of the present invention will be described with reference to FIGS. 8 to 10.

An unstable applied voltage Vin containing a ripple component as shown in FIG. 8 is supplied to the input terminal TI. Applied voltage Vi
n is supplied from a power supply device composed of a rectifier circuit and a smoothing circuit. A pulsed start signal vl as shown in FIG. 10(A)K is supplied to the terminal). The start signal Vl is supplied to the set terminal of the flip-flop circuit (hereinafter referred to as FF) 36 via the OR circuit section in FIG. Therefore, the voltage level of the output Q of FF37 is as shown in Fig. 10 (
It becomes H level as shown in B). The voltage level of the output Q of the FF 36 also becomes H level as shown in FIG. 10(C).

Then, the analog switch 8W1 is turned on by the Q output of the FF 36. Note that the analog switch SWI is illustrated as a mechanical structure for convenience of explanation. The multiplier Akara is the voltage v3 that is the square of the applied voltage Vin.
is obtained, and this voltage ψ is supplied to line L1 via switch SWl. The capacitor and resistor constitute a thermal response simulation circuit as described above. The voltage v3 on line 11 is supplied to each of the four voltage comparison terminals, each of which has a non-inverting input terminal. Note that the voltage v obtained between the multipliers
l, voltage controlled oscillator (hereinafter referred to as vCO) 39
Also supplied.

On the other hand, a gray scale signal (not shown) having a predetermined voltage level difference is supplied to the terminal T4. The gradation signal is converted into an analog signal by the D/A converter 5, and is supplied to the inverting input terminal of the operational amplifier via the resistor &. Further, a negative polarity DC voltage is supplied to the inverting input terminal from the power source Es via a resistor.

Note that the voltage level of the power source & may be a voltage level corresponding to the upper limit θl of the temperature α shown in FIG.

The operational amplifier constitutes a current adder,
The output car M becomes a reference signal for determining the upper limit temperature θl and the lower limit temperature θ2 in addition to θa, eb, and ec.

Note that the Zener diode ZDI is for obtaining a voltage difference corresponding to the temperature difference between the upper limit temperature θ1 and the lower limit temperature θ2. The resistor is for adjusting the gain of the operational amplifier.

Then, the inverting input terminal of the voltage comparison Masuda is connected to Fig. 1θ (
The voltage ■θl shown in D) is supplied, and the voltage Vθ2, which is lower than the voltage Vθ·l by the Zener voltage VZD, is supplied to the inverting input terminal of the voltage comparator 21.

The control operation for controlling the temperature will be described below.

When the voltage level on line ll gradually increases as shown in Figure 10 (D) and reaches voltage Vθl, an output signal is obtained from voltage comparison Masuda at time 11, and in synchronization with this, a monostable multivibrator (hereinafter referred to as The output signal of 40 (referred to as MM) becomes H level. Each input terminal a of the AND circuit 41
, b, and c all become H level, and the output signal also becomes H level. The output signal of the ANL1 circuit 41 is output from the OR circuit 4.
Since it is supplied to the reset terminal of Ff'I via 2,
The Q output of FF36 becomes L level.

Then, when the analog switch 8Wx is turned off and the voltage on the line 71 gradually decreases by %1, an output signal is obtained from the voltage comparator 21, and the output of the MM 43 becomes H level. The AND circuit hook input terminals ab and c also fall to the H level, and the output signal also becomes the H level. AND
The output signal of the circuit material is supplied to the set terminal of the FF 36 via the OR circuit.

The above circuit operation starts from time 11 in FIG.
This is the current circuit operation.

Then, when the FF 36 is switched to the reset state again, the analog switch SWl is turned on again, and the 1
The same circuit operation as from time 0 to time t1 is performed. As a result, an application pulse having a waveform as shown in FIG. 10(C) is outputted from the output terminal T2 and supplied to the thermal head.

By the way, while the above-mentioned operation is being performed, voltage v8 is supplied to C039. When voltage v3 increases, V
The output frequency of CO39 gradually shifts to a higher frequency.

Note that this frequency change is, for example, 500KHz to 2M
A change of 78 degrees in Hz is sufficient. The output signal of VCO39 is
An AND circuit circuit valve is supplied to an energy counter (hereinafter referred to as a counter) 46.

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 count 4 is accelerated accordingly.

While energy counting is being carried out using a counting instrument,
Control operations from time tS to time t8 are performed, and control operations from time tB to time t4 are repeated.

Then, the time of the impression I 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 (Fi). be done. By the carry signal Vc, FFs 36 and 5 are switched to the reset state, and the analog switch 8Wi is also switched to the off state. That is, the shimmy wharf 1 circuit shown in FIG. 9 all returns to the initial state after the decrease based on equation (2).

As described above, the temperature θ1 is controlled by increasing the temperature. When the above-mentioned operation is performed due to temperature rise, the floor Il! supplied to the terminal T4. ■θl, Vθ2
All you have to do is lower it. The same applies to temperature &. Then, as in the case of temperature output, an applied pulse as shown in FIG. A thermal recording is performed.

Note that the voltage ■θ1. In order to obtain a voltage difference between Yes and Yes, replace the Zener diode ZDl with a normal diode (
(not shown) may be connected in the forward direction. In this case, a voltage difference occurs between the voltages Θ1 and VO3 due to the forward voltage of the diode. Furthermore, a resistor or a variable resistor may be used in place of the Zener diode W1. Also, an oscillator is provided between the multipliers described above in place of vcog,
The above-mentioned equation (4) may be satisfied.

Although the above embodiments are examples in which thermal recording paper is used as the recording paper, according to the technical idea of the present invention, the recording paper or recording medium is not limited to thermal recording paper.

For example, if a heating operation as described above is performed on a recording medium that has a magnetic layer made of two or more types of ferromagnetic powder with different Curie points, the amount of magnetization of the recording medium can be controlled (i.e., the amount of magnetization is set to an intermediate level). setting) then becomes possible. - As mentioned above, the present invention enables the maximum set temperature of the thermal head to be switched in multiple stages, and the recording immersion degree of the recording medium recorded by the heat is controlled by this switching. , it is possible to reproduce halftones extremely easily.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are a perspective view of the structure of the thermal head, a perspective view of the firewood, and an enlarged cross-sectional perspective view thereof, Figure 2 is a schematic cross-sectional view showing an example of the schematic configuration of a thermal recording device, and Figure 3 is a thermal recording device. FIG. 4 is a characteristic diagram showing the relationship between paper color density and temperature. FIG. 4 is a characteristic diagram showing the relationship between applied pulses and temperature of the thermal head. 5 to 10 show an embodiment of the present invention, FIG. 5 is a circuit diagram showing the basic configuration of a simulation circuit, and FIG. 6 is a relationship between applied pulses and temperature in the simulation circuit. Figure 7 is a humidity characteristic diagram when the temperature is changed stepwise; Figure @S is a waveform diagram of the power supply voltage; Figure 9 is a circuit diagram of a thermal recording device to which the present invention is applied; FIG. 10 is a waveform diagram for explaining the operation of the same circuit. In addition, in the symbols used in the drawings, Cs, 翫
・・・・・・・・・・・・Capacitors and resistance problems constituting the simulation circuit, 21・・・・・・・・・・・・・・・・Voltage comparison circuit 5・・・・・・・・・・・・・・・・・・
・Addition of D/A converter ・・・・・・・・・・・・・・・
......Operation amplifier a, 42...--
・・・・・・・・・OR circuit, 37・・・・・・・−・
・・・・・・・・・Between flip-flop circuits ・・・・・・
・・・－・・・・・・・・・・・・Multiplier 39 ・
・・・・・・・・・・・・・・・・・・・・・Voltage controlled oscillator circuit 40.8・・・・・・・・・・・・・・・・・・
・Monostable multivibrator 41, ■, Tsuge...
......AND circuit 46 ......
・・・・・・・・・・・・・・・It is a counter. Agent Patent Attorney Hiroshi Aisaka @ Figure 1 (σ) 1 1st animal (shi) 2nd day 30 Figure 4 Figure 5th day @ 60 7th yen 10th day (voluntary) procedural amendment document July 1920 IQ Day 1982 Patent Application No. 62985 2 Title of the invention Thermosensitive recording silver amount 3 Relationship to the case of the person making the amendment Patent applicant I 1 Location Nishi-Shinjuku 1-chome, Shinsho-ku, Tokyo @ 2B Book 2 Name (127) Roku Konishi Photo Industry Co., Ltd. 4, Agent 8 Contents of amendment (1): "Color pattern" in lines 2 to 1 from the bottom of page 2 of the specification is corrected to "color pattern." (2) In the 5th line of page 4, "The color becomes white." is corrected to "The print density will decrease significantly." (3), "Prescribed voltage" on the last line of page 4 is corrected to "prescribed power." (4), "During pulse" on page 5, line 12 is corrected to "during pulse". (5), 3rd line from the bottom of page 5, re(J/C)J is r
Correct it as C(J/'C)J. (6), page 6, line 1 r Q=Rq(1-eYfE
) Correct J to 1 "θ=Rq(1-eCR)J. (7)," on page 11, line 3, "voltage comparator support, a" is changed to "
Voltage comparison Zenmi, 21" is corrected. (8), "gradation signal" on page 11, line 8 is corrected to "gradation signal lamp." (9), "Reset state" on page 13, line 6 is corrected to "set state." Of the α values and drawings attached to the application, Figures 5 and 9 will be corrected as shown in the attached documents. Figure 5

Claims (1)

[Claims] 1. A thermal head that heats the recording object and/or a temperature simulator *71@Wr configured by at least the heat capacity and thermal resistance of the recording object, and a comparison circuit that compares the output of the simulation circuit with a predetermined voltage. and,
and an accumulator for deriving a signal when the output of the simulation circuit reaches a predetermined power level, and the maximum temperature setting of the thermal head can be switched in a plurality of stages, and by this switching, the recording medium is recorded by heat. 1. A thermal recording apparatus characterized by being configured to control the recording density of the recording medium to produce an intermediate recording density on the recording medium.