JPH01299064A - Thermal recorder - Google Patents

Abstract

PURPOSE:To constitute each circuit in the number of the half of conventional devices, and to obtain a low-cost device by mounting a power supply control circuit selectively supplying electric power at every heating resistor corresponding to a divided picture signal and a reading control circuit generating a transfer clock, a data latch signal and a printing command signal. CONSTITUTION:When the number of the reading of the same picture signal is twice and the number of the picture elements of one scanning line four, a reading control circuit 1 reads a picture signal corresponding to one scanning line stored in a line memory 2 as the first time, and inputs the picture signal to the S1 of a shift register 4 as an input picture signal (a) while supplying the S1 with a transfer clock (b) at every two picture-element period conformed to the picture element timing of odd-number picture elements. The reading control circuit 1 reads a picture element signal as the second time, and inputs the picture element signal to the S1 of the shift register 4 as an input picture element signal (a) while supplying the S1 with a transfer clock (b) at every two picture-element period conformed to the picture element timing of even-number picture elements. On the other hand, a power supply control circuit 3 supplies the R1 and R3 of a heating resistor 8 in the odd number with a power supply f1 after the completion of the transfer of the first picture signal and the R2 and R4 of the heating resistor 8 in the even number with a power supply f2 for the second time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal recording device used in facsimiles and the like.

[Conventional technology]

Thermal recording devices used in facsimiles and the like currently have shift registers with the number of stages corresponding to the number of pixels in one scanning line to be recorded, and each stage of the shift register is connected to the number of pixels in the same scanning line. A typical configuration is such that a driver circuit corresponding to the above energizes a heating resistor at a pixel position to be recorded. FIG. 3 is a block diagram of an example of a conventional thermal recording device, and FIG. 2 is a timing diagram for explaining the operation of the conventional example. In order to simplify the explanation, it is assumed that the number of pixels in one scanning line is four.

The input image signal a is input to the left end S1 of the shift registers S1 to S4, and is sequentially transferred to S1, S2, S3 by the transfer clock b.
, S4 and is transferred to the right side. When the transfer is completed, the image information 2 of the scanning line is transferred to each shift register 81 to S4.
1 to p4 are data latched by data latch signal C.
~Latched at L4. At this point, the shift register 81
~S4 enables image signal input for the next one scanning line.

The data outputs d1 to d4 of the data latches L1 to L4 are ANDed with the print command signal e by the AND circuits A1 to A4, and if the print command signal e is true and the data output d1 is
Only when d4 is black information, the heating resistors R1 to R4 supplied with power by the power source f are energized by the driver circuits D1 to D4. Although the explanation here assumes that the number of pixels in one scanning line is 4 to simplify the explanation, in reality, for example, in a thermal recording device that records on 210 mm wide paper at a pixel density of 8 pixels/mm, the number of pixels in one scanning line is 4. The number of pixels is as high as 1,680, so it is best to implement the shift register, data latch, AND circuit, and driver circuit, as explained in Figure 3, on one integrated circuit for each 64 pixels, for example. It is.

[Problem to be solved by the invention]

In the above-mentioned conventional thermal recording device, each pixel constituting a scanning line must be equipped with a circuit group such as a shift register, data latch, AND circuit, driver, etc., so the cost of the elements of these circuit groups and The disadvantage is that the device becomes expensive due to the built-in manufacturing cost.

[Means to solve the problem]

The thermal recording device of the present invention has a line memory that stores pixel signals for one scanning line, and a plurality of pixel signals based on a transfer clock.
a shift register that stores the pixel signal divided into;
A data latch that stores and holds the output of this shift register using a data latch signal, an AND circuit that calculates and outputs the AND of the output of this data latch and a print command signal, and a heating resistor that generates heat according to the output of this AND circuit. a driver circuit that supplies current to the body; a power supply control circuit that selectively supplies power to each of the heating resistors corresponding to the divided image signals; and a readout control circuit that generates the transfer clock, data latch signal, and print command signal. are doing.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a control timing diagram for explaining the operation of this embodiment.
This embodiment will be described assuming that the number of readout ports for the same image signal is two, and the number of pixels in the -scanning line is four.

The reading control circuit 1 first reads out the image signals for one scanning line stored in the line memory 2 and inputs them to the shift register 81 as an input image signal a, and also synchronizes them with the pixel timing of the odd-numbered pixels. A transfer clock b every two pixel cycles is supplied, and the input pixel signal a is sequentially transferred to S1,
Transfer to S2 and the right side. At this time, since the transfer clock b is not generated at the pixel timing of even-numbered pixels, the image information p2 and p4 are not transferred. When the transfer is completed, the image information for the scanning line is transferred to 81 and S2 of each shift register 4. p1 and p3 are latched into Ll and R2 of the data latch 5 by the data latch signal C. At this point, the image signals 81 and S2 of the shift register 4 can be inputted for one scanning line of the next time.

When the print command signal e is supplied from the read control circuit 1, the data outputs d1 and d2 of the data latch 5 Ll and R2 are ANDed with the print command signal e by the AND circuit 6 AI and A2. , and only when the print command signal e is true and the data outputs d1 and d2 are black information, R1 and R3 of the heating resistor 8 supplied with power by the power supply 1 are connected to the D of the driver circuit 7.
1, energizes by D2. As a result, R of the heating resistor 8
1 and R3 are respectively energized according to the image information p1 and p3. Also, at this time, R2 and R of the heating resistor 8
4 is not energized because the power source f2 is not supplied with power.

Next, the reading control circuit 1 reads out the pixel signal for one scanning line, which is the same as the previous transfer, stored in the line memory 2 for the second time, and uses the pixel signal 81 of the shift register 4 as the input pixel signal a.
At the same time, a transfer clock b is supplied every two pixel periods in accordance with the pixel timing of even-numbered pixels, and the input pixel signal a is sequentially transferred to the right side as S1 and S2. At this time, since the transfer clock b is not generated at the pixel timing of the odd numbered pixel, the image information p1 and p3 are not transferred. When the transfer is completed, the image information for the scanning line is transferred to 81 and S2 of each shift register 4. p2 and p4 are latched into Ll and R2 of the data latch 5 by the data latch signal C. At this point, the shift register 4 81 and S2 can receive image signals for the next scanning line.

On the other hand, the power supply control circuit 3 supplies two power supplies to R2 and R4 of the even-numbered heating resistors 8 after the second image signal transfer is completed.
, and the supply of power f1 to R1 and R3 of the even-numbered heating resistors 8 is suspended.

When the print command signal e is supplied from the read control circuit 1, the data outputs d1 and d2 of the data latch 5 Ll and R2 are ANDed with the print command signal e by the AND circuit 4 Al and A2. Only when the print command signal e is true and the data outputs d1 and d2 are black information, R2 and R4 of the heating resistor 8 supplied with power from the power source f2 are energized according to the image information p2 and p4, respectively. That will happen. Also at this time,
R2 and R4 of the heating resistor 8 are energized according to the image information p2 and p4, respectively. Further, at this time, R1 and R3 of the heating resistor 8 are not energized because the power source f1 is not supplied.

According to the above configuration, the shift register 4 and the data latch 5 for energizing the heating resistor 8 according to image information are provided.
Each circuit such as the AND circuit 4 and the driver circuit 7 can be configured with half the number of conventional circuits. Furthermore, the read control circuit 1 and the power supply control circuit 3 can be easily constructed using a microprocessor, transistors, and the like.

〔Effect of the invention〕

As explained above, the present invention can provide an inexpensive device by driving a heat-generating resistor using a shift register, a data latch, an AND circuit, and a driver circuit each having a number of 1/multiple pixels of one scanning line. effective.

[Brief explanation of the drawing]

1 and 2 are a block diagram of an embodiment of the present invention, a block diagram of an example of a tie for explaining the operation of this embodiment, and a timing diagram for explaining the operation of a conventional example. 1... Read control circuit, 2... Line memory, 3...
・Power supply control circuit, 4...Shift register (SL, S2
), 5... Data latch (LL, R2), 6... AND circuit (Al, A2), 7... Driver circuit (DI
, D2), 8... Heat generating resistor (R1-R4).

Claims (1)

[Claims] A line memory that stores pixel signals for one scanning line, a shift register that stores the pixel signal divided into multiple parts by a transfer clock, and data that stores and holds the output of this shift register using a data latch signal. a latch, an AND circuit that calculates and outputs the AND of the output of the data latch and the print command signal, a driver circuit that energizes the heating resistor according to the output of the AND circuit, and A thermal recording device comprising: a power supply control circuit that selectively supplies power to each of the corresponding heat generating resistors; and a read control circuit that generates the transfer clock, data latch signal, and print command signal.