JPH03283763A - Thermal printing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a thermal printing method in a thermal facsimile machine, and more particularly to prevention of thermal paper from sticking due to melting and assimilation when colors are developed by a thermal head.

(Prior art) Fig. 4 is a diagram showing the flow of processing of received image data by a thermal facsimile machine. This is coded image data and is stored in the buffer memory section 3 via the modem 2. Then, the signals are sequentially decoded in the decoding section 4 and input to the line buffer 60 of the thermal printer section 6 through the line buffer memory section 5.

Here, if there is image data in the line buffer memory section 5, the thermal printer section 6 reads and writes it at a constant speed, but the communication speed of one image data and the decoding speed in the decoding section 4 are Depending on the data, the print speed may not be sufficient, and in this case, the print output will be accompanied by intermittent operations.

(Problems to be Solved by the Invention) FIG. 5 is a side view showing an outline of the configuration of the thermal recording section of the thermal printer section shown in FIG. 6
A thermal paper 64 coated with a coloring material is sandwiched between the paper sheets 3 and 3, and the paper is fed in the sub-scanning direction y by rotation of a platen roller 63.

Here, the recording part of the thermal paper 64 is coated with a sensitizing material, a color fading prevention material, a protective layer material, and other materials in addition to the coloring material, and the thermal head is heated by the heat generating element of the thermal head. Although there are differences in degree depending on the type, coloring is accompanied by melting and solidification. It is known that if the feeding of the thermal paper is stopped during this solidification, development occurs in which the thermal head 62 and the thermal paper 64 become stuck together.

In the intermittent print output explained in Fig. 4 above, the thermal head and thermal paper become stuck during a temporary pause in the printing operation, which has a significant negative impact on the rise of thermal paper feed when the printing operation is restarted. The situation is illustrated in FIG.

Figure 6 shows the thermal paper feed amount (displacement) α after restarting printing operation.
(vertical axis), and the delay in the rise of the thermal paper feed is determined by the black rate of the line before the print operation is stopped and the print energy applied to the heating element per dot (three examples are shown as an example, a < b < c ), but the larger both of them are, the worse the start-up of thermal paper feeding becomes.6 In other words, when the printing energy is larger than the printing energy a, the elapsed time t (horizontal axis) after restarting the printing operation is taken.

In this case, the thermal paper feed amount α after restarting the printing operation varies greatly from line to line, as shown in FIG. is almost never done. and,
When the adhesive peels off on the 2nd and 3rd lines, the thermal paper is fed as shown by diagonal lines, and on the 3rd line,
Thermal paper is fed an extra amount to compensate for the delay in the second line.

Therefore, the feed amount α (vertical axis) of the thermal paper is the sub-scanning direction (y
) is considerably larger (approximately twice) than the print pitch β (level indicated by the broken line). In this rotation, white sushi occurs in the so-called main scanning direction between the second and third lines or between the third and fourth lines.

The generation of white sushi occurs as follows. Figure 8 shows
The timing chart of the drive pulse (a) of the step motor, the drive pulse (b) for the heating element 61 of the thermal head 62, and the relationship between the thermal paper feed amount (c) are shown. That is, the pulse motor that rotates the platen roller 63 and feeds the thermal paper advances by one phase at the rising edge of the drive pulse (a), and energization to the heating element of the thermal head occurs at the H level of the drive pulse (b). It is carried out at the time of (b)
shows the heating element driving pulses for one line at a time,
It is common to divide the heating elements on the thermal head into several groups and drive them in a time-division manner.

By the way, the feeding of thermal paper is generally stopped (d) as shown in (c).
) At the subsequent rise, the ideal feed rate curve shown by the broken line (C') deviates from the ideal feed rate curve shown by the broken line (C') as the thermal paper and the thermal head become attached at the same time, as shown in the actual 1iA (c'''), resulting in white in the main scanning direction. Streaks appear.

As described above, when print output is intermittent due to the input state of image data, the present invention prevents sticking between the thermal paper and the thermal head after the print operation is temporarily stopped, and prevents the occurrence of white smudges on the output image. The purpose is to prevent.

(Means for Solving the Problems) In order to achieve the above object, the invention described in claim (1) includes a buffer memory section that stores compressed and encoded data received at an undefined speed as is; A decoding unit that reproduces the stored content of the buffer memory unit into original image data, a line buffer memory unit that stores the image data decoded by the decoding unit, and a thermal print of the stored content of the line buffer memory unit in sequence. In a thermal facsimile device having a thermal printer section and a line buffer in the thermal head itself of the thermal printer section, when the thermal printer section finishes printing an arbitrary line, the line buffer of the thermal head itself and the line buffer memory section If the image data for the next line has not been input to the line buffer memory section, a means for sending thermal paper for N lines after the printing of the line is completed and image data for the first line has been input to the line buffer memory section. It is characterized by comprising means for pulling back the thermal paper by N lines at a certain point in time, and means for performing a normal printing operation thereafter.

In addition, the invention described in claim (2) is provided when the image data for the next line has not been input to the line buffer memory and line buffer memory section of the thermal head itself when printing an arbitrary line is completed in the thermal printer section. means for feeding the thermal paper for N lines after the completion of printing of the line, and pulling back the thermal paper for N+1 lines at the time when image data for the next line has been inputted into the line buffer memory section; It is characterized by comprising a means for sending out a line, and a means for performing a normal printing operation thereafter.

(Function) In the invention described in claim (1) of the present invention, when print output is intermittent due to the input state of image data, after the printing operation is completed, the thermal paper is continuously fed by N lines, and then the next line When the image data for the number of minutes has been input, it is pulled back by the amount of N lines sent out to prevent sticking of the thermal paper and the thermal head and the occurrence of white streaks in the main scanning direction.

The invention described in claim (2) of the present invention is characterized in that the thermal paper of claim (1) is pulled back by an extra line and is fed by one line, thereby preventing the printing position before and after the pause from being too far apart. This completely prevents the occurrence of white streaks in the main scanning direction.

(Example) As mentioned above, the sticking of thermal paper to the thermal head is achieved by the coating components on the thermal paper that melted at the same time as the color development of the thermal paper cooled and solidified during the pause in the printing operation, and then applied to the surface of the thermal head by the platen roller at that time. This is caused by being placed in a crimped state.

Therefore, in the present invention, the coloring section is once sent out from the contact part with the thermal head in the paper ejection direction (sub-scanning direction) during a pause in the printing operation, and then returned to its original position after cooling. Prevents sticking of thermal paper and thermal head.

FIG. 1 is a graph showing the feeding and retracting operations of thermal paper according to the present invention, and (a) is a graph showing the heating element 6 of the thermal head.
This corresponds to the drive pulse shown in FIG. 8(b).

(b) is described in claim (1) of the present invention.

(c) is a graph showing the feed amount of each thermal paper according to claim (2) of the present invention. *(h) is a graph for feeding and pulling back the thermal paper based on the number of black dots on the L line, which will be described later.

In the case of (b), the drive pulse to the thermal head heating element shown in the figure (a) is applied after printing the last line (a') before a temporary pause in the printing operation (d).
The paper is fed out in the paper ejecting direction (sub-scanning direction y in Fig. 5) by an extra line (b'), and then the platen roller 63 is reversed to feed the paper in the paper ejecting direction prior to the printing operation after the - time pause. The colored part of the thermal paper is removed from the pressure bonding part of the platen roller 63 by pulling it back by one extra line.

This prevents sticking to the thermal head during cooling.

After the first coloring part has cooled down, the thermal paper is pulled back to its original position, and the first line of print (a”) is placed at the normal stop position (
From e), the feeding of the thermal paper is smoothly started.

In addition, (f) in the figure (b) shows hysteresis in the power transmission system with respect to the normal stop position (e). For example, the play in the gears of the power transmission system from the motor of a part of the plotter to the platen shaft of the platen roller 63, and the timing Due to elongation or contraction of the belt, there may be a difference between the feed-back position and the normal stop position (e) by one line.

If the amount of hysteresis (f) in this power transmission system is large, the printing positions before and after the pause will be too far apart.

This also causes white streaks to occur in the main scanning direction. Therefore,
In the invention described in claim (2), as shown in FIG. ) to solve the problem.

Next, the noise generated due to the motor reversing during printing and the thermal paper feeding operation required during the intermittent pause time,
As a whole, it takes time, and if possible, figure 1 (b) and (Q
) would like to reduce the number of implementations.

To satisfy this request, if the number of black dots in the image data is small, the degree of adhesion between the thermal paper and the thermal head can be kept low. By performing the normal operation (FIG. 8) without taking the measures (b) and (c), it is possible to prevent unnecessary noise from being generated and the printing time from being extended.

FIG. 2 shows an example of the configuration of a black dot number counter circuit that takes the above measures, and FIG. 3 shows a timing chart of signals for explaining its operation.

The image data (DATA) signal (FIG. 3) is input to the ENABLE terminal of the counter circuit 7 in FIG.
2...The threshold black bit number input is added to each N, and the clock (CLOCK) is input to the CLOCK terminal.
A signal (FIG. 3) is input.

As shown in Figure 3, at the rising edge of the CLOCK signal, the DA
If the TA signal is at H level, black data is input to the thermal head 62, and if the TA signal is at L level, white data is input to the thermal head 62. Then, when the input is serially completed for all bins, the LO
Image data is transmitted in parallel to a portion of the driver of each heating element 61 of the thermal head 62 by the AD signal.

In this case, the DATA signal and CL signal are output at the same time as the thermal head.
Since the OCK signal is received and the DATA signal is input to the ENABLE terminal, only the number of black data is counted. In other words, CLOC is activated only when the DATA signal is at H level.
Count K signals. And a predetermined number (black data)
are inputted in advance through the upper N terminals (l, 2, . . . , N), and set for each line by the LOAD1 signal (not the LOAD signal inputted to the thermal head 8).

When the number of black data counted by the counter circuit 7 reaches a predetermined number, a ripple carry signal (Ripple
carry) is output and the first-order RS flip-flop 8
The output of the sequence controller 9 is fixed at H level when the image data for the first line has not been input to the line buffer memory unit 5 at the time when line writing is completed.
If the Q output of the RS flip-flop 8 is at H level,
As shown in FIG. 1(h), the thermal paper is fed out in the paper discharge direction by one line, and is pulled back by one line or +1 line.

Further, if the output of the RS flip-flop 8 is at L level, normal thermal paper conveyance is performed.

In addition, the CLR signal is a clear (CLEAR) signal, and a signal of a predetermined voltage (for example, 5V) is always sent to the CLR terminal of the counter circuit 7, and the terminal connected to the counter circuit detects the difference between lines, and then The counter circuit 7 and the RS flip-flop 8 are reset before inputting the line.

(Effects of the Invention) As explained above, the invention described in claim (1) of the present invention prevents the thermal head from adhering to the thermal head because the thermal head and the thermal paper do not come into pressure contact with each other during cooling of the coloring part of the thermal paper. This eliminates the occurrence of white smear caused by uneven thermal paper feeding in intermittent drive printing, and provides a high-quality print appearance image.

Furthermore, the invention as set forth in claim (2) can prevent deterioration in image quality due to white smear that occurs when hysteresis in the platen roller power transmission system is large. Furthermore, in the invention described in claims (1) and (2) above, the number of black dots exceeds a certain number in order to prevent the noise caused by the pulling back operation of the thermal paper and the overall printing time to become unnecessary. Since the thermal paper is fed and pulled back only at certain times, the above-mentioned problem can be solved.

[Brief explanation of drawings]

No. 19 is a graph showing the operation of feeding and pulling back thermal paper according to the method of the present invention, FIG. 2 is a side view of the configuration of a black dot number counter circuit, No. 3 wI is a timing chart of a signal for explaining the operation of No. 2 Wi, and No. 4 5 is a diagram showing the flow of processing of received image data in a thermal facsimile device in which the present invention is implemented, FIG. A diagram showing the rise characteristics of the thermal paper feed amount when the print operation is restarted. Figure 7 is a diagram showing the thermal paper feed amount for each line after the print operation is restarted. Figure 8 is a diagram showing the rise characteristics of the thermal paper feed amount for each line after the print operation is restarted. Driving pulse and Fig. l...Telephone line, 2...Modem, 3...Buffer memory section, 4...Decoding section,
5... Line buffer memory section, 6... Thermal printer section, 7... Counter circuit, 8...
-RS flip-flop, 9...sequence control unit. 60... line buffer, 61... heating element, 62
...Thermal head, 63...Platen roller
64...Thermal paper. Shows the relationship between thermal paper feed amount α

Claims (2)

[Claims] (1) A buffer memory section that stores compressed and coded data received at an undefined speed as is, a decoding section that reproduces the stored contents of the buffer memory section into original image data, and a A thermal facsimile device having a line buffer memory section for storing image data, a thermal printer section for sequentially thermally printing the stored contents of the line buffer memory section, and a line buffer in the thermal head itself of the thermal printer section, the thermal printer When printing an arbitrary line is completed in the section, if image data for the next line has not been input to the line buffer of the thermal head itself and the line buffer memory section, the image data for N lines will be The apparatus comprises a means for feeding thermal paper, a means for pulling back the thermal paper by N lines when the image data for the next line has been inputted into the line buffer memory section, and a means for performing a normal printing operation thereafter. Features thermal printing method. (2) When the thermal printer unit finishes printing a given line, if the image data for the next line has not been input to the line buffer memory and line buffer memory unit of the thermal head itself, the print process continues after the printing of the line is completed. means for feeding the thermal paper for N lines; means for pulling back the thermal paper for N+1 lines when the next line of image data has been input into the line buffer memory section; and feeding the thermal paper for one line; 2. The thermal printing system according to claim 1, further comprising means for performing a printing operation.