JPS5871176A - Heat sensitive recording device - Google Patents

Abstract

PURPOSE:To obtain records without density irregularity, by counting the interval between the previous information picture recording to the next information picture recording by a counter, and controlling conducting time to heating resistor elements in correspondence with the counted value. CONSTITUTION:When a record starting command signal SCAN is inputted, a latch circuit 7F stores the counted value of the counter 7D at that time. A selecting circuit 6 is controlled by an output C of said value in order to select resistors R14-R16 so as to obtain the optimum conducting and heating time. When the counted value of the counter 7D is stored in the latch circuit 7F, the counter 7D is cleared by a clearing signal CLEA from a delay circuit 7B. An oscillating circuit 7C is restarted, and the interval to the next recording is counted. At this time, the time length of the high level in an output A from the oscillating circuit 7C is controlled by an analog switch 7E so that it becomes longer with the increase in the counted value of the counter 7D. Therefore the correcting times do not become excessively frequent in the region the changes in residual temperature is few.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording device used in facsimiles, printers, and the like.

Various types of recording devices such as facsimiles and printers have been put into practical use, but the devices are compact and easy to simplify because they do not require an image mechanism or fixing mechanism, and maintenance is easy because they do not require toner or ink. Thermosensitive recording devices are often adopted because of the fact that the recording paper is relatively inexpensive. A typical thermal recording device has a plurality of heating resistors corresponding to pixels, and the heating resistors are selectively heated with electricity in accordance with the image information signal to be recorded, and this heat is transferred to thermal recording paper to form an image. is configured to record. The recording head of a thermal recording device used in facsimiles is equipped with a large number of heating resistors arranged perpendicularly to the recording paper transport direction, and the recording paper is moved continuously each time an image for one scanning line is recorded. This is a configuration that records information images. In addition, a thermal recording device equipped with a recording head in which KNXM heating resistors are arranged in a matrix, such as a serial printer, is configured to record a series of information characters by moving the recording head in the character arrangement direction every time one character is recorded. be.

In any thermal recording device, a heating resistor provided in a recording head is repeatedly superelectrically heated. However, the recording start interval of each scanning line and the recording start interval of each character are often not constant. If a certain amount of power is injected into the heat-generating resistor during recording, the temperature rise of the heat-generating resistor will not be constant, resulting in uneven recording.Figure 1 takes a thermal recording device used in a facsimile as an example. A detailed explanation will be given with reference to FIG. ~R12 are arranged in one row along the scanning line,
Heat generating resistor 1 (1) to R4.

R5~](,8,1(9~a12 are grouped. One end of each heat generating resistor R1~1(,4) of the first group is connected in common after passing through a backflow blocking diode D1~D4Y. Group selection transistor TI is also connected to the collector of 1. 5. 2nd and 3rd group heating resistor R5~
Similarly, one end of F(,8,R,9~)t12 is connected in common after passing through the reverse current blocking diodes D5~D8, D9~1)12, and is connected to the group selection transistor 'I'f(
, 2, 'I'J't3. 4+The other ends of the heating resistors R1 to R12 are connected to the image information signal applying transistors TR4, 'I'R5.

It is directly connected to the collectors of lR6 and 'I'R7.

The energization timer 1 connects the capacitor C1 and the resistor I (outputs the energization pulse PW at the time interval determined by the time constant of 13 and group selection gates 2 to 4σ) each time the trigger signal 'r' RI G is input. A common input is 'f'.

The image information signal processing circuit 5 is the image information 1 horoscope VII) EO
When the recording start command signal 5 (CA, N) is input and the image information signal V1.DEO for 7.1 scanning lines is input, when the recording start command signal 5CAN is input, the i% voltage and timer 1 are input.
Trigger signal T'RIG to start, enable signal EB1 to control gate 2 and transistor 'I' R4
~Heating resistor R1~R to control TR70 base
Pixel information signals 81 to S4 corresponding to image information signals 81 to S4 are simultaneously outputted to heat the heating resistors R1 to R4 for a predetermined time according to the image information signals 81 to S4.
IG and enable signal 1) H2 and heating resistor R5~R
The pixel information signals 85 to 88 corresponding to 8 are simultaneously outputted to heat the heating resistors 115 to 115 to I (8) for a predetermined period of time,
Furthermore, the trigger signal T RI (, +, enable signal ID B 3, and pixel/clearance signals S9 to S corresponding to χ·1 to the heating resistors R9 to I (]2) are simultaneously outputted to activate the heating resistors. R9 to R, 12Y are heated for a predetermined length of time to complete recording of one scanning line on the information side by γ1°.

The operation of this thermosensitive recording apparatus will be explained with reference to the time chart of FIG. 2. The generation interval τ1-τ3 of the recording start command signal S(, 'AN) differs depending on the content of the transmitted document.

During the information image recording period of each scanning line.

Enable 1 every time trigger signal 7rR, IG occurs
Words EBI~EB3 are output sequentially and outputs B1~133 of gates 2~4 are transistors 'I''l'L1~T.
It 3 constant time τ14)! However, in the information image recording of the second scanning line, the group selection transistor TL3 of the nest 3 is turned on and the heating resistors 1 and 9 are turned on.
After R12 is energized and heated, there is a long period during which the heating element stops until the third scanning line 0) recording start command signal 5CAN is reached. This occurs when there is a margin in the sent document. According to the international standard (
) The high-speed 5-row machine called 3 machines speeds up the paper feed speed in the margin area to shorten the heating period.

Since there is a limit to the paper feed speed, the recording start command signal 5C
It makes no difference whether the AN generation interval τ1-τ3 is kept constant. Under these circumstances, if we take one heating resistor F%1 as an example and pay attention to its temperature characteristics T, we can see that the information image recording of the 1'th scanning line is recorded at a short interval compared to the information image recording of the previous scanning line. is started, the temperature rise of the heating resistor R1 is I
When information image recording of the next scanning line is started at a scanning interval τ2, the temperature rise chapter is as low as T2.Therefore, the energizing pulse PW (=B] with the same time width τ4 is always applied.
2. If the on-time of the transistors TRI to TR3 was controlled by T3:3), the temperature rise T of the heating resistors R and 10 would change, causing density unevenness in the recorded information image.
Ru.

On the other hand, since the density of the printed image changes due to changes in the temperature of the substrate of the recording head on which the heating resistors It1 to R]2 are provided, the temperature change of this substrate is detected and the heating resistors R1 to R]2 are installed. A heat-sensitive recording device has been proposed in which the electric heating time of 12 hours is controlled.However, since it is difficult to install a temperature detector close to the heating resistor, there is a delay of one hour.

Although it is effective in correcting gradual fluctuations in substrate temperature, it is not possible to precisely respond to changes in the residual temperature of the heating resistor.

Therefore, an object of the present invention is to solve the drawbacks of the prior art described above.
<Sh. Controls the heating time of energization to the heat generating resistor element by 1 hour in close response to changes in the residual temperature of the fluorine heat generating resistor. The purpose of the present invention is to provide a heat-sensitive recording device.

In order to achieve this objective, the present invention provides a variable frequency JTL1 oscillator that starts firing simultaneously with the recording of each information image and within a substantial time period from the previous information image recording to the next information image recording. means for switching an oscillation constant so that the oscillation output period of the variable period oscillator is sequentially lengthened according to an increase in the count value of the variable period oscillator; , an energization time control circuit for changing the energization time to the heating resistor element during the next information image recording according to the count value of the counter between the previous information image recording and the next information image recording; By one circuit,
The present invention is characterized in that energization heating of the heat generating resistor element is controlled in accordance with the residual Y degree of the heat generating resistor element, thereby preventing the occurrence of density unevenness in the recorded information image.

An embodiment of the present invention will be described below based on FIGS. 3 to 6. Figure 3 is an electrical circuit diagram of the entire recording section, Figure 4 is a time chart of its operating core, Figure 5 is a detailed diagram of the interval measuring circuit of Figure 3, and Figure 6 is its operation time chart.

In Figure 3 and Figure 4, 1 heating resistor R, 1 to R1
2 is divided into three groups, and each heating resistor R1 to R
One end of 12 is connected to a group selection transistor T11.1 common to each group i after passing through backflow blocking diodes 1)1 to D12. ]~TR,: connected to one, and the other end is connected to the image information signal application transistors TJt4~Tit7 with the same order of each group being shared. In addition, the image information signal processing circuit 5 inputs the pixel information signal VTI)EO and the recording start command signal SCA, N pieces, and after recording the image 'rH report signal T D EO for one scanning line, outputs the recording start command signal. When SCA and N are input, energization timer 1
The trigger signal T1 that activates the TG and the enable signal T(j l(1-II) that controls the gates 2 to 4) is used to control the TG and the gates 2 to 4. The configuration is the same as that shown in Figure 1.The energization timer 1 includes a capacitor C1 that determines the time constant.
and a plurality of resistors 1t14 to 1416 are connected, and these resistors 1t14 to R116 are selectively enabled by the □W selection circuit 6. The interval measuring circuit 7 receives a recording start command signal S.
CAN is input and the interval τ between the previous recording start command signal 5CAN and the next recording start command signal 5CANO is measured, and if the interval is short based on the measurement result output C, it is output from the energization timer 1. When the time width of the energization pulse PW is short and one interval is long, the selection circuit 6 is configured to select the resistors R, 14 to R16 so that the time width of the energization pulse PW becomes longer.

Therefore, as shown in the operation time chart shown in FIG. Output time width τ5 short (, previous signal 5CA
When the interval τ2 of N(q is long, the output time width of the gates 2 to 4 is as long as τ6. Due to this n5, when the residual temperature of the heating resistors R1 to 1112 is low, When the residual temperature is long and the residual temperature is daytime, the heating time of the western army becomes short, and the heating temperature T of the heating resistor for recording information images becomes a constant value Tl, regardless of the recording interval τ, and the recording a degree unevenness is Does not occur.

As shown in FIG.
The oscillation circuit 70 is equipped with an oscillation circuit 7C controlled by a clear signal CLEA delayed by B and a counter 71). R20+11.25)C2)
.

Resistance R for determining τL (=−R, 25・C2)
17~l(, 25 and capacitor C2 are connected, and resistor R
17 to Ft24 are selectively enabled by the switching analog switch 7EK. The output A of the oscillation circuit 7C is counted by a counter 7D, and the output B of this counter 7D controls the analog switch 7E and the selection (B).
A latch circuit 7F is input to obtain a signal C controlling the line 6.

The operation of the interval measuring circuit 7 is as shown in FIG. 6. When the recording start command signals SCA and N are input, the latch circuit 7F stores the count value of the counter 71) at that time. Resistor 1 (14 to R16) is selected to control the selection circuit 6 with output C and obtain the optimum energization heating time τ.After memorizing the count value of counter 7D, counter 7D is cleared by clear signal CIJA, and The oscillation circuit 7C also restarts and starts interval measurement for the next recording.The high-level time widths τH1 to τH4 of the output A of the oscillation circuit 7C are set by resistors R17 to R20 or the analog switch 7E so that they become sequentially longer. It is selected based on the output B of the counter 7D.
In the region where the residual temperature of R]2 has little change, there are an unnecessarily large number of analog switches 7E (the energization time cannot be controlled (and the counter 7I has a small capacity)).

There is an advantage that the latch circuit 7F can control the energization time appropriately in accordance with the residual temperature characteristics.

In addition, if the pixel information is a day in your information image recording, the residual temperature of the heating resistor will be somewhat lower, but the leakage heat from the adjacent heating resistor will be transmitted, so the effect will be small.

Also, the intervening heating resistance elements do not need to be physically independent (
, or may be formed by forming an area electrically partitioned by band-shaped heating resistors.

As described above, according to the present invention, the interval between the previous information image recording and the next information image recording is measured by a counter to control the energization heating time for the heating resistor element, so the repetition interval of information image recording is Even if a change occurs in the residual temperature, fine correction control can be performed to prevent uneven recording density from occurring. Moreover, the oscillation circuit that provides the measurement signal k to the counter is of a variable period type, and outputs a signal according to the change characteristics of the residual temperature, thereby reducing the chances of correction in areas where the residual temperature changes little. It is possible to control the energization time in accordance with the residual temperature characteristics using small-capacity circuit components.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of a thermal recording section of a conventional facsimile, FIG. 2 is an operation time chart thereof, FIG. 3 is an electric circuit diagram of a thermal recording section according to an embodiment of the present invention, and FIG. 4 is its operation time chart. An operation time chart, FIG. 5 is an interval measuring circuit diagram, and FIG. 6 is an operation time chart. R1-R12... Heat generating resistor, 1... Energization timer,
7... Interval measurement circuit, 7C... Oscillation circuit, 71
)... Counter, 7E... Analog switch, latch circuit, R, 19-1't24... Resistor for oscillation output cycle control. Fig. 3 7 2 Φ <--CV+I-Q ωωωH Fig. 5 Fig. 4 Fig. 6 Procedural amendment (method) February 25, 1980 Patent Office Chief Award Island 1) Haruki Tono 1, Indication of the incident 1981 Patent Application No. 170140 2 Name of the invention
Enthusiasm Recording System 3 Person making the amendment (Relationship with 'l As stated in the appendix of the patent applicant (1) 1 patent claim between the 3rd and 4th line of the first member of the specification) 421

Claims (1)

[Claims] 1. A current is applied to a large number of heat-generating resistive elements in accordance with the recording image information to cause them to generate heat, and an information image is recorded on the thermal recording paper, and then the heat-sensitive recording paper and the heat-generating resistive elements are moved relative to each other to record the next information image. In the heat-sensitive recording device, the control circuit that causes current to flow through the heating resistive element includes a variable period oscillator that starts oscillation in synchronization with the recording of each information image, and a variable period oscillator that starts oscillation in synchronization with the recording of each information image, and a control circuit that supplies current to the heat-generating resistor element. A counter that counts the output of the variable period oscillator that occurs during a substantial period of time until image recording, and oscillation that gradually increases the oscillation output period of the variable period oscillator as the count value of this counter increases. a constant switching means, and a passing time for changing the time of passing through the heating resistor element during the next information image recording according to the count value of the counter between the previous information image recording and the next information image recording. A heat-sensitive recording device characterized by having a control circuit.