JPS58158275A - Heat-sensitive recorder - Google Patents

Abstract

PURPOSE:To reduce the occurrence of small white lines in the boundary of blocks by lenthening the electrification time for dots in the boundary of adjacent blocks of different print timings in the heating resistor row of facscimile, etc. CONSTITUTION:The output time for outputs from the 2nd to the 31st, among picture signals of dots of a block 32 stored in a shift register 4, is controlled by signals from a terminal 3 after the output is given to AND gates 7-1-7-30. Also, the 1st and 32nd dot outputs to be the boundary of the blocks are directly given to a dot driver 6. When all black is printed in designated blocks by the driver 8, the 1st and 32nd dot outputs become high level during the time T2, and on the other hand, the dot outputs from the 1st to 32nd become high level during the time T1. Thus, on the basis of T2>T1, the lowering of temperature in the boundary of the blocks is compensated and the occurrence of white small lines is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording device such as a facsimile or a printer.

In heating resistor arrays for thermal printing in facsimile machines, printers, etc., applying power to all of the heating resistors at the same time may be complicated or expensive due to the circuit configuration, so N heating resistor arrays ( Normally, one line is divided into blocks (N is an integer of 2 or more) and printed by dividing it into at most N timings. Figure 1 shows how 9 blocks divided into 5 are printed at 5 timings, and the average temperature distribution of the heating resistor when printing black on the tip corresponding to each block. The reason why the average temperature appears low is because, for example, when the third block is being printed, the second and fourth blocks are not printed, so the boundary between the second block and #I3 block and the This is because heat dissipates more easily near the boundary between the third block / and @420 block than inside the third block, and therefore the temperature becomes lower. Due to a decrease in the average temperature distribution at the boundaries of blocks caused by this difference in print timing, the print density decreases at the boundaries of blocks with different print timings, resulting in white #1IIi!
The disadvantage was that it left behind.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional technology.Accordingly, an object of the present invention is to eliminate the problems at the boundaries of each block due to the difference in printing timing between adjacent blocks of heating resistors as described above. It is an object of the present invention to provide a heat-sensitive recording device in which the occurrence of thin white lines is reduced.

To achieve the above object, the thermal recording device according to the present invention divides all the heating resistors in the drive circuit of the heating resistor array for thermal printing into N blocks (N is an integer of 2 or more),
In a thermal recording device that prints all dots in each block at the same timing and prints one line by dividing it into at most N timings, the energization time of dots at the boundaries of blocks that are adjacent to each other but have different printing timings By controlling the distance so that it is long, it is possible to reduce the occurrence of thin white lines at the boundaries of diblocks.

Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings.

Referring to FIG. 2, the first embodiment of the present invention relates to recording a binary image signal, including an image signal input terminal 1, a latch pulse input terminal 2. In addition to the signal input from the control signal input terminal 3, there is also a 32-bit shift register with a latch, a thermal head 5, each block 32 of the thermal head 5, which has 1728-bit heating resistors connected in a matrix of 54 blocks each with 32 bits. A dot driver 6 that flows the latched 32-pit shift register 4 corresponding to the high level of the latched 32-pit shift register 4, and a block driver 8 that selectively applies voltage to each block of the AND gates 7-1 to 30 and the thermal head 5. including.

Of the image signals of 32 dots per block stored in the shift register 4, the 2nd to 31st dots other than the block boundaries
The outputs of the dots are connected to AND gates 7-1 to 7-30, so that the output time can be controlled by a control signal inputted through the control signal input terminal 3. Further, the outputs of the 741st dot and the 32nd dot at the block boundaries are directly connected to the dot driver 6 without going through an AND gate. Latch pulse input terminal 2 p
FIG. 3 shows the input latch pulse instructing the latch timing of the shift register 4, the control signal input from the control signal input terminal 3, and the input signal of the dot driver. When printing all black in the block designated by the block driver 8 in FIG. 2, that is, when all the outputs of the shift register 4 are High, the dot driver input signal Fi of the 1st dot and the 32nd dot is generated at the boundary of the block. According to the equation shown in FIG. 3, the function Hjgb of T2 is obtained. On the other hand, the dot driver inputs of the 2nd to 31st dots other than the block boundaries become High during TlQ as shown in FIG. In this way, by making the energization time longer for the dots at the block boundaries than for the other dots, it is possible to compensate for the temperature drop at the clock boundaries and reduce the occurrence of white thin lines at the block boundaries.

FIG. 4 is a block diagram of a second embodiment of the present invention, which corresponds to halftone recording. Read clock generation circuit 12, clock selection data selectors 13 and 14° RAM 15 and 161
Picture credit maximum power terminal 17. Data selector 1g for data selection
, gradation designation circuit 19° ROM selection data set/2
0. #! ROM 21 and 22 for lit specification. Block detection circuit 23. Shift register with latch 24. Dot Drinoku 25° thermal head 26. It consists of a block driver 27.

The RAMs 15 and 16 each have a capacity to store two blocks of image signals, and when one is reading the image signal input from the image signal input terminal 17, the other reads the image signal read immediately before. The operation of sending the data to the data selector 18 for data selection is performed alternately.

The image signal stored in the gradation control MAM is read out repeatedly in the gradation designation circuit 19 for each readout, and the gradation designation data output from the image signal upper gradation designation ROM 21 or 22 is compared. Then, when the image signal>gradation specification data, the output of the gradation specification circuit 19 is set to High,
At other times, 0 gradation designation RO is performed by changing the voltage application time according to the image signal by setting it to Low.
M22 stores gradation designation data such that voltage application time is longer for each gradation than M21. As a reminder, the data corresponding to the voltage application time of O, that is, white printing, are the same. Now, when printing a block specified by the block 2 printer 27, the block edge detection circuit 23 detects the boundary of the block, and the gradation control for the dots at the boundary of the block is performed by the gradation specifying ROM 22. By controlling the gradation of the dots in the gradation specifying ROM 21, the voltage application time to the dots at the block boundaries is longer than the voltage application time to the dots other than the block boundaries at the same gradation. It is possible to reduce the occurrence of thin white lines at the boundaries of

As explained above, the present invention has the effect of reducing the occurrence of thin white lines at the boundaries of blocks by controlling the energization time to be longer for the dots at the boundaries of blocks that are adjacent to each other and have different printing timings. be.

[Brief explanation of drawings]

Figure 4 shows the conventional method of dividing one line into five blocks and printing with five tie-ups, and the average temperature distribution of the heating resistor when printing black tip metal corresponding to each block.
The figure is a block diagram of the first embodiment of the present invention, FIG. 3 is a tinging chart thereof, and FIG. 4 is a block diagram of the first embodiment of the present invention. FIG. 2 is a block diagram of the second embodiment. l...-image signal input terminal, 2...latch pulse input terminal, 3...control signal input terminal, 4...
...Ki shift register with latch, 5...
Thermal head, 6... Dot driver, 7-
1 to 30---AND game), 11---Write clock generation circuit, 12---Read clock generation circuit, 13 and 14---Clock selection data Selector, 15 and 16...RAM%
17... Image signal input terminal, 18...
Data selector for data selection, 19... Gradation specification circuit, 20... Data selector for ROM selection, 21 and 22... ROM for tone specification, 23.
...Block end detection circuit, 24 ... Shift register with latch, 25 ... Dot driver, 26 ... Thermal head. IV U...ノThaノLS -ff-Chori-11 Hayabusa 3I21 Procedural amendment (method) Director General of the Patent Office 1, Indication of the case 1982 Patent Application No. 410
No. 72 No. 2, Title of the invention: Thermal brass device 3, Relationship to the amended person's case Applicant: 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4, Agent Address: 5-37-8 Shiba 5-chome, Minato-ku, Tokyo 108 Resident Mita Building 5゜Date of amendment order: June 29, 1980 (shipment date) 6. Name of item in the specification subject to amendment 7, Details of the contents of amendment ``3. Detailed description of the invention'' is inserted before ``the present invention'' on page 1, line 13 of the book.

Claims (1)

[Claims] Divide the heating resistor array for thermal printing into N blocks (N is an integer of 2 or more), print all dots in each block at the same timing, and print 1 line/at most N blocks. In a thermal recording device, adjacent to each other,
A thermal recording apparatus characterized in that the apparatus further comprises a control means for lengthening the energization time of the dots at the boundaries of different blocks of printing tying.