JPS612578A - Thermal recorder - Google Patents

Abstract

PURPOSE:To enable to record with stable density even when using a commercial power source accompanied by fluctuations in voltage, by passing electric currents to a plurality of heating resistor elements until electric energy reaches a reference level set for each average resistance of the resistor elements. CONSTITUTION:The voltage of the commercial power source is lowered to a predetermined value by a transformer 21, the resultant source current is rectified by diodes 22 to be a pulsating current TV, which is further smoothed by a capacitor 23, and the resultant voltage is impressed on the heating resistor elements 24 and a voltage-power converting circuit 29 as a recording voltage RV. The average resistance R of the resistor elements is inputted as a signal SEL into a reference level setting circuit 32 through a terminal 36. The circuit 32 calculates a reference level LEV, which is outputted to a level-detecting circuit 31. When it is detected by the circuit 31 that the electric energy INT has reached the reference level LEV, an RS flip-flop 28 is reset, recording pulses PLS are turned OFF, and the supply of electric currents to the resistor elements 24 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal recording device that can record with stable density even when using a commercial power supply with large voltage fluctuations.

Conventional configuration and its problems A thermal recording device uses a thermal head in which a plurality of heat-generating resistive elements are arranged to apply electricity in accordance with image information to color a thermal recording medium, and uses a commercial power supply. Accordingly, an inexpensive recording device can be constructed. In this case, the commercial power is stepped down with a transformer, rectified with a diode,
The voltage smoothed by a capacitor is used as input to the recording device, but changes in load cause fluctuations in stain pressure, and the recording voltage applied to the heating resistor element also fluctuates, so optimization control is necessary to optimize recording density. It becomes necessary.

FIG. 1 shows a conventional recording device.

In the figure, 1 is a transformer for commercial power supply, 2 is a transformer 1
A diode that rectifies the output of 2 to make it a pulsating current TV, 3 is a capacitor that smoothes the pulsating current TV rectified by diode 2,
Reference numeral 4 indicates a plurality of heat generating resistor elements arranged in the thermal head; 5 indicates a heat generating resistor element 4 in one-to-one correspondence with the heat generating resistor element 4;
6 is a gate circuit that corresponds one-to-one with driver circuit 5 and drives driver circuit 6; 7 converts the serial image signal PIX input from terminal 13 into parallel and outputs it to gate circuit 6; a shift register; 8 an RS flip-flop that outputs recording pulses PLS that simultaneously open the gate circuits 6 according to the contents of the image signal FIX; 9 a square circuit that squares the recording voltage RV and converts it into electric power; 10
11 is an integration circuit that outputs the power amount INT from the output of the square circuit 9; 11 is a level detection circuit that detects that the power amount INT is constant and has reached bell A; 12 is a recording start trigger TRG
13 is an input terminal for the image signal PIX, and 14 is an input terminal for the image signal sample clock CLK.

FIG. 2 is a timing chart of a conventional thermosensitive recording device. The operation will be explained with reference to FIGS. 1 and 2. The commercial power source is stepped down to a predetermined value by a transformer 1, rectified by a diode 2 to become a pulsating current TV, smoothed by a capacitor 3, and supplied to a heating resistor element 4 and a square circuit 9 as a recording voltage RV.

On the other hand, the serial image signal PIX from the input terminal 13 is written into the shift register 7 by the image signal sample clock CLK from the input terminal 14. After the writing is completed, the image signal PIX is converted into parallel signals and outputted to one input side of the gate circuit 6. Next, a recording start trigger TRG is input from the terminal 12, and at the same time as resetting the integrating circuit 1o, the RS flip-flop 8 is turned on, and the recording pulse PLS is turned on.
Start recording.

The recording voltage RV is converted into electric power by a square circuit 9 and input to an integrating circuit 10. Integrating circuit 1° is recording pulse P
While LS is on, the power amount INT is output to the level detection circuit 11. The level detection circuit 11 has the above-mentioned electric power IN.
When T becomes constant and reaches bell A, the RS flip-flop 8 is reset, the recording pulse PLS is turned off, and the current supply to the heating resistor element 4 is stopped.

However, in order to obtain the same level of recording density on the recording medium corresponding to the heat generating resistive elements, the heat generating resistive elements must have the same amount of heat, and therefore must be supplied with the same amount of power. However, due to manufacturing errors,
Heat generating resistive elements usually have different resistance values.

Further, the heat generating resistive element of the thermal head, which is sometimes replaced as a consumable item, has a different resistance value depending on the thermal head. Therefore, the electric power INT is calculated from the applied voltage value without considering the resistance value of the heat generating resistor element to be driven.
In the case described above, in which the heating resistor element 4 is energized until this value becomes constant and reaches Bell A, the amount of supplied power and therefore the amount of heat generated will differ for each thermal head that is replaced, and as a result, , causing variations in the density of the recording medium.

FIG. 3 shows the relationship between the recording voltage V and the recording power P using the resistance value of the heating resistive element 4 as a parameter. The figure shows that there is a difference in recording power P between the minimum resistance value Rmin and the maximum resistance value Rmax. That is,
This means that the amount of electricity is calculated based on each characteristic curve,
When a certain amount of electric power is supplied to the heating resistor element,
This means that variations occur in the amount of heat generated and thus in the density of the recording medium.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems, and aims to provide a thermal recording device that can record at a stable density even when using a commercial power source that causes voltage fluctuations.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a thermal recording device that includes means for converting a recording voltage applied to a plurality of heating resistive elements into electric power, and means for converting this electric power into electric energy. and means for setting a reference level to be compared with the electric energy according to the average resistance value of the heating resistor element, and means for detecting that the electric energy has reached the reference level.

By energizing the plurality of heating resistive elements until the amount of electric power reaches a reference level set for each average resistance value of the heating resistive elements, the recording medium corresponding to the plurality of heating resistive elements develops color. Optimize the recording density level.

DESCRIPTION OF THE EMBODIMENTS FIG. 4 is a block diagram of a thermal recording apparatus showing an embodiment of the present invention. In Fig. 4, 21 is a commercial power supply transformer;
2 is a diode that rectifies the output of the transformer 21 into a pulsating current; 23 is a capacitor that smoothes the pulsating current rectified by the diode 22; 24 is a plurality of heat generating resistor elements arranged in a thermal head; 26 is a heat generating element; A driver circuit 26 has a one-to-one correspondence with the resistor element 24 and energizes the heat-generating resistor element 24, a gate circuit 26 has a one-to-one correspondence with the driver circuit 25 and operates the driver circuit 25, and a numeral 27 denotes a series image input from the terminal 34. A soft register 28 converts the signal FIX into parallel signals and outputs them to the gate circuit 26. A soft register 28 is an RS flip-flop that outputs a recording pulse PLS that opens the gate circuit 26 in accordance with the contents of the image signal PIX.

29 is means for converting the recording voltage into electric power according to the resistance value of the heating resistor element, that is, the electric power P based on the recording voltage RV and the representative value R0 of the average resistance of the heating resistor element.

This is a voltage and power conversion circuit that calculates and outputs.

That is, when the recording voltage RV is V, the power P at the representative value R0. is calculated as Po-υ2/R0, and is output to the integrating circuit 3o.

The integrating circuit 30 is a means for converting electric power into electric energy, integrates electric power P0 to calculate electric energy INT, and records pulse P0.
While LS is on, the power amount INT is output to the level estimating circuit 31.

32 is means for setting a reference level, and the average resistance value R of the actual heating resistor element is inputted from a terminal 36, and this resistance value R
A reference level LEV is calculated from the recording voltage RV and is output to the level detection circuit 31.

The level detection circuit 31 is a means for detecting that the electric energy has reached the reference level, and the electric energy INT is at the reference level LE.
It is detected that V is reached.

33 is an input terminal for the recording start trigger TRG, 34 is an input terminal for the image signal FIX, and 36 is an image signal sample clock CL.
The input terminal K and 36 are the input terminals for the signal SEL indicating the resistance value of the heating resistive element 24. FIG. 5 is a time chart of the thermal recording apparatus of this embodiment. The operation of the thermal recording apparatus of this embodiment will be explained with reference to FIGS. 4 and 5.

The commercial power source is stepped down to a predetermined value by a transformer 21, rectified by a diode 22 to become a pulsating current TV, smoothed by a capacitor 23, and applied to a heating resistor element 24 and a voltage/power conversion circuit 29 as a recording voltage RV.

The image signal PIX is input to the terminal 34 and written to the shift register 27 in response to the image signal sample clock CLK input to the terminal 35. After the writing is completed, the image signal PIX is converted into parallel signals and output to one input side of the gate circuit 26. Next, a recording start trigger TRG is inputted from the terminal 33, and at the same time the integrating circuit 30 is reset, the R87 lithoprop 28 is set, the recording pulse PLS is turned on, and the heating resistor element 24 is energized.

On the other hand, the average resistance value R of one heating resistor element is inputted to the reference level setting circuit 32 via a terminal 36 as a signal SEL. A reference level LEV is calculated by the reference level setting circuit 32 and outputted to the level detection circuit 31.

When the level detection circuit 31 detects that the electric energy INT has reached the reference level LEV, it resets the RS flip-flop 28, turns off the recording pulse PLS, and
Power supply to the heating resistor element 24 is stopped.

Although the explanation has been omitted in this embodiment, the same effects as the present invention can be obtained in the following embodiments as well.

(Support) When m bits of heat generating resistive elements are collected into one block, n blocks are collected and connected in a matrix, and a heat generating resistive element to be driven is arbitrarily selected.

(b) We have explained the case where the reference power level LEV is the power amount calculated based on the average resistance value R of the heat generating resistor element, but the temperature of the thermal chamber, the energization cycle of the heat generating resistor element, and the color development of the thermal recording medium When using the power amount calculated based on sensitivity etc. as the standard power amount level.

(1) Digitize the recording voltage with an A/D converter,
When the subsequent processing is also digitalized and the voltage/power conversion circuit and reference level setting circuit are configured with ROM, switches, etc.

) When the output of the shift register is stored in a single latch.

(3) When the heating resistor element is divided into a plurality of blocks and recorded in block units.

(When the input power source is half-wave rectified instead of full-wave rectified.

(When omitting the smoothing capacitor.

Effect of the invention According to the present invention, even if the input voltage fluctuates.

Even if the recording voltage fluctuates due to a difference in the number of simultaneously energized elements determined by the black ratio of the image signal, recording with stable density can be performed. Further, even if a stabilized power source with little voltage fluctuation is used as the recording power source, the value of the output voltage can be freely set regardless of the resistance value of the heating resistor element. Furthermore, even if the average resistance value of the heat generating resistor element is different for each converted thermal-\rad, it is possible to produce color with an appropriate recording density according to the image signal.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional thermal recording device, Figure 2 is a timing chart of a conventional thermal recording device, and Figure 3 is a characteristic showing the recording voltage and recording power with the resistance value of the heating resistor element as a parameter. 4 is a block diagram of a thermal recording apparatus showing an embodiment of the present invention, and FIG. 6 is a timing chart of the thermal recording apparatus shown in FIG. 4. 29...Voltage/power conversion circuit, 30...
・Integrator circuit, 31...Level detection circuit, 32.
...Reference level setting circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Illustration number tX.

Claims (1)

[Claims] means for converting the recording voltage applied to the plurality of heating resistive elements into electric power; means for converting the electric power into electric energy; and a reference level to be compared with the electric power according to the average resistance value of the heating resistive elements. and a means for detecting that the amount of electric power has reached the reference level, the thermal recording device comprising: a means for setting the amount of electric power to a reference level; and a means for detecting that the amount of electric power has reached the reference level; .