JPH0454424B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording method in facsimile, and relates to the problem of density correction of recorded images.

In general, thermal recording systems have a problem in that the state of heat storage in the recording head affects the density of the recorded image. On the other hand, in facsimile, there is a problem in that the recording cycle for each line varies depending on the processing speed of the sending device. For this reason, with facsimiles that use the conventional thermal recording method, there is no problem if the processing speed of the other device is not much different from that of the own device, but if the processing speed of the other device is extremely slow or if the resolution is low even if it is not so slow, the recording The amount of heat stored in the head decreases, and the overall density of the recorded image decreases.
There was a drawback that clear recorded images could not be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal recording method that eliminates the drawbacks of the prior art described above and can always provide the same image density regardless of the processing speed of the other device.

In order to achieve this object, the present invention is characterized in that the recording frequency of image information for each line is changed in accordance with the processing speed of the sending device.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the main part configuration of a facsimile device to which the present invention is applied, where 1 is a CPU, 2 is a
ROM, 3 is RAM, 4 is input section, 5 is modem,
6 is an output section, and 7 is a thermosensitive recording device.

The CPU 1 is a microprocessor that processes data in parallel in 8-bit units, the ROM 2 is a read-on memory that stores programs necessary for the processing of this embodiment, and the RAM 3 is a random access memory that temporarily stores data. be. this
The RAM 3 includes a FIFO area that sequentially stores the received data of every 8 bits inputted from the input unit 4 and sequentially retrieves it in the order in which it was stored, and a FIFO area that alternately stores decoded image information one line at a time. 2
A line buffer LBF area for each line is secured.

The input section 4 is an interface that converts the serial reception data inputted from the modem 5 into 8-bit parallel data and outputs it onto the data bus 8. This is an interface that takes in data and outputs it to the thermal recording device 7 in 256-bit units.

The thermal recording device 7 is equipped with a thermal recording head having heating elements for 2048 bits per line, and is configured to record one line in 8 times of 256 bits each.

FIG. 2 shows a conceptual diagram of the operation of FIG. 1.

In the case of this embodiment, the work performed by the CPU 1 is roughly divided into three parts, A, B, and C.
Processing is performed to transfer the 8-bit data stored in the input section 4 to the address in the FIFO area. Work B
Now, 8-bit data is extracted from the FIFO area, decoded, and stored in the LBF area.
Further, in job C, when one line of drawing information is stored in the LBF area, it is sequentially extracted in 8 bits and 256 bits are stored in the output unit 6. Of these jobs A, B, and C, the CPU 1 normally executes job B, and executes job A in response to an interrupt signal generated when 8-bit data is stored in the input section 4. Furthermore, work C is executed by a timer interrupt signal generated at regular intervals. Also, the work at this time is in priority order A>C>
Perform in order B.

Therefore, the received image data output bit by bit from the modem 5 is converted into 8-bit data by the input section 4, and is sequentially stored in the FIFO area of the RAM 3. Next, the 8-bit data stored in the FIFO area is taken out by the CPU 1 in the order in which it was stored, decoded, and then stored in one of the LBF areas. At this time, if one line of decoded writing and drawing information is already stored in the other area, that writing and drawing information is transferred to the output section 6 in units of 8 bits. As a result, the output section 6
When 256 bits of calligraphy information is stored, it is output to the thermal recording device 7 and recorded.

In this manner, the thermal recording device 7 performs eight recording operations of 256 bits each, records one line, and prepares for recording the next one line. At this time,
If the processing speed of the other party's sending device is approximately the same as that of the own device, no particular problem will occur; however, if the processing speed of the other party's device is slow, it will be difficult to prepare the next line of drawing information in the LBF area. As a result, the temperature of the thermal recording head decreases when the next line is recorded, and as a result of repeating this recording operation for recording one page, the overall recording density becomes thinner.

Therefore, in this embodiment, in order to prevent the recording density from decreasing due to such a heat dissipation phenomenon of the thermal recording head, the processing speed of the other device is checked in advance. In this case, the processing speed of the other device can be determined by the communication with the other device during the protocol before receiving facsimile data. Therefore, if the processing speed of the other device is slow,
The calligraphic information for each line is written twice.

That is, assuming that the own device currently has a processing speed of 5ms/, the CPU 1 first checks that the other device
5ms/, 10ms/, 20ms/, 40ms/,
Find out if it is one of the G2 machines. As a result, if the other device is 5 ms/ or 10 ms/, the wait time until recording the next line is short, so the double write flag is reset. On the other hand, the other device
In the case of 20ms/, 40ms/, the double write flag is set or reset depending on the resolution at that time. This is true regardless of whether the recording surface of the thermal head forms a recorded image on the recording paper or not.
In addition, since the recording paper is in pressure contact even during sub-scanning of the recording paper, the heat accumulated after the heat sensitive head generates heat is transmitted through the recording paper and radiated. From this, when the scanning line density is 3.85/mm, the amount of movement of the recording paper in the sub-scanning direction is twice as large as when it is 7.7/mm, and the heat accumulated in the recording head increases due to the long press-contact state. Heat is radiated through the recording paper. Therefore, the scanning line density of 3.85/mm, which is coarser, is better.
Heat radiation is greater than 7.7/mm. For example, when the scanning line density is 7.7/mm, the amount of heat stored in the recording head is large, so the double writing flag is reset. However, when the scanning line density is 3.85/mm, the amount of heat stored is small and the next line is Since the temperature of the recording head will have decreased by the time of recording, in this case, the double write flag is set. Furthermore, when the other device is a G2 machine, it takes 166.6ms/ to process one line.
Since a recording waiting time of 161.6 ms/minute occurs, in this case, the twice-write flag is unconditionally set.

Next, in accordance with the resolution at that time, if the scanning line density is 3.85/mm, a 2-line feed flag is set in order to set the sub-scanning line density to a resolution corresponding to that. However, if the scanning line density is 7.7/mm, the 2-line feed flag is reset.

Before recording the calligraphy information, the CPU 1 performs such a preparation process and then enters the recording operation process shown in FIG. 3b.

In other words, when reception of one page has been completed, the recording paper is ejected and all processing is completed, but if reception has not yet been completed, the decoded calligraphic image of one line to be recorded is Check whether information is available in the LBF area. As a result, if the area is prepared, the calligraphy information is sequentially extracted from that area to the output unit 6 and recorded by the thermal recording device 7 in the same manner as described above.

In this manner, after recording one line of image information, the sub-scanning motor is driven to perform sub-scanning feed for one line, and then it is checked whether the double writing flag is set. As a result, if it has been set, the processing speed on the transmitting side will be slow, so the same one line of calligraphic information is recorded by the thermal recording device 7 again. After that, after performing sub-scanning feed for one line, switch the LBF area,
Recording operation processing for the next line is performed in the same manner. On the other hand, if the double writing flag has been reset, it is next checked whether the 2 line feed flag is set, and if it is set, the resolution at that time is 3.85/mm. ,
After performing sub-scanning feed for one line, the LBF area is switched and recording operation processing for the next line begins. However, if the 2-line feed flag has been reset, there is no need to perform sub-scanning feed.
Switch LBF area.

In this way, if the other party's sending device is a G2 machine,
Alternatively, if the scanning line density is 3.85/mm at 20ms/ or 40ms/, by writing the graphic information twice, the heat storage state of the thermal recording head is always kept constant, and the state of the other device is A recorded image with the same density can be obtained regardless of the image density.

As described above, according to the present invention, there is no longer a problem in which the overall recording density decreases depending on the partner device as in the conventional apparatus, and clear recorded images with the same density can always be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the main parts of a facsimile device to which the present invention is applied, Fig. 2 is a conceptual diagram for explaining its operation, and Fig. 3 a and b explain the operation of one implementation of the present invention. This is a flowchart for 1...CPU, 2...ROM, 3...RAM, 4
...Input section, 5...Modem, 6...Output section, 7...
...Thermal recording device, 8...Data bus.

Claims (1)

[Claims] 1 In a thermal recording method in which decoded calligraphic information is sequentially recorded line by line, the heat storage state of the thermal head is kept almost constant according to the processing speed and resolution of one line of the sending facsimile machine. A thermal recording method characterized by changing the number of times that calligraphic information for a line is recorded.