JPH05338243A - Recording method and recorder - Google Patents

Abstract

PURPOSE:To increase recording speed while power source capacity for recording is suppressed small by counting number of a black picture element from number of the picture element of one line part and performing different recording when a black picture element ratio is not exceeding preset value, and when it is not less than, preset value. CONSTITUTION:Number of a black picture element is counted from number of the picture element of one line part. The black picture element ratio thereof is compared with the preset value (1/2). When the black picture element ratio is not exceeding 1/2, one line part is collectively recorded. In order to record the following line, collective recording of one line for performing carriage of one line part is performed. When the black picture element ratio exceeds 1/2, the number of black picture element is divided into an odd picture element and an even picture element and dividedly recorded. At this time, when buffer memory residue exceeds the specified quantity, the odd picture element is recorded for one line. Thereafter the even picture element is recorded for the same line. In order to record the following line, division recording of one line for performing carriage of one line part is performed. In other words, both the recording line of the odd picture element and the recording line of only the even picture element are alternately set to perform a diced division recording.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for supplying and recording an image signal to a thermal head in which a large number of heating elements are arranged corresponding to each pixel of one line. More specifically, according to the ratio of the number of black pixels in the pixel signal for one line, one line is collectively recorded, or divided into an odd pixel and an even pixel, and only the odd pixel is recorded and only the even pixel is recorded. The present invention relates to a method and apparatus for alternately setting the lines to be recorded and recording in a checkered pattern.

[0002]

2. Description of the Related Art A thermal head in which a large number of heating elements corresponding to the number of pixels of one line are arranged is often used in a recording apparatus used in a facsimile machine or the like. Black pixels are recorded on the recording paper by selectively energizing the heating elements corresponding to the black pixels in the input pixel signal. When the recording paper is a thermal paper, the color is developed by heat, and when a thermal transfer ribbon or the like is used, the ink is transferred by the heat to the recording paper.

In such a recording apparatus, it is the simplest and high-speed recording method to record pixels of one line simultaneously. However, since there is a case where all the one lines are black pixels, in the case of the batch recording method, a power source having a capacity capable of simultaneously supplying the recording power to all the heating elements is required. Therefore, not only the capacity of the power source increases and the cost also increases, but also the device incorporating the power source becomes large. Therefore, various recording systems have been developed that can downsize the power source, especially for low-cost small-sized facsimile machines.

One example thereof is a system in which one line is divided into a plurality of pieces for recording. That is, the thermal head is divided into a plurality of blocks, and the respective blocks are shifted in timing to sequentially supply recording power to record pixels. However, in the simple divided recording method, in order to perform recording for one line, it is necessary to energize each block for a required time and repeat it for the number of blocks. Therefore, it takes a considerable amount of time regardless of the number of black pixels. Even if the number of black pixels is small, the recording time cannot be shortened as a whole. Therefore, there is a method in which the number of unrecorded black pixels in each block is counted, the block with the smallest number of black pixels is selected preferentially, and at the same time, the black pixels at the same position in other blocks are also recorded. (JP-A-55-50772).

Another example is a method of collectively recording one line by using a small power source which does not have a capacity capable of simultaneously supplying recording power to all heating elements. In other words, the number of black pixels on one line is counted, and if the power supply capacity of the power supply is exceeded during the normal recording time, the supply time is increased instead of decreasing the amount of power supply to the heating element and recording is performed. (JP-A-59-89073).

[0006]

However, according to the former method of the improved types as described above, depending on the pattern of the pixel signal, all the black pixels of the latter block are recorded at the time of recording the previously selected block, and the recording is performed. Sometimes it saves time, but not always. Further, for example, in the case of two divisions, it is rare that the recording of the first block completes the recording of all the subsequent blocks at the same time. Therefore, the recording speed is not so high. Further, when all the one lines are black pixels, the one-line simultaneous recording is performed, and the power supply capacity has to be estimated accordingly, so that it is substantially meaningless to divide. Further, in the latter method, when the number of black pixels in one line exceeds a predetermined amount, the energizing time to the heating element is increased in accordance with the increase in the number of black pixels, so that the recording speed does not become high after all.

An object of the present invention is to provide a recording method capable of improving the recording speed while suppressing the power supply capacity for recording to be small, and a compact and economical recording apparatus using the recording method.

[0008]

The present invention is a method of supplying a pixel signal to a thermal head in which a large number of heating elements corresponding to the number of pixels of one line are arranged and recording. The basic flow chart is shown in FIG. In the present invention, first, black pixels are counted from the pixel signals for one line. Next, when the black pixel ratio is equal to or less than the set value (1/2 or less), one-line batch recording for simultaneously recording pixels of one line is performed.
When the line where the black pixel ratio exceeds the set value is continuous, the pixel of one line is divided into an odd pixel and an even pixel, the even pixel is ignored, and the line in which only the odd pixel is recorded and the odd pixel are ignored. The lines for recording only even pixels are alternately set and recorded. At this time, the paper feed for one line is performed between the recording of the line recording only the odd pixels and the line recording only the even pixels. In this way, checkered pattern division recording is performed.

[0009] Here, when dividing and recording in a checkered pattern,
It is preferable to increase the power supply per pixel as much as possible according to the margin of power supply capability. In addition, the pixel signal to be recorded is temporarily stored in the buffer memory, and the pixel signal is sequentially supplied to the thermal head. When the black pixel ratio exceeds the set value and the remaining amount of the buffer memory is large, one line is recorded. Pixel is divided into an odd pixel and an even pixel
It is preferable to record the lines separately.

As an apparatus for carrying out this recording method,
(a) A thermal head in which heating elements corresponding to the number of pixels for one line are arranged, (b) a buffer memory having a capacity for a plurality of lines for temporarily storing pixel signals to be recorded, (c)
Selection means for dividing the pixel signal for one line into odd pixels and even pixels, (d) an odd pixel memory and an even pixel memory for separately holding the selected odd pixel and even pixel, and (e) one line A black pixel counter that counts black pixels from pixel signals, and (f) black pixel ratio is a set value (however, 1/2
Below) 1 line of pixels are recorded simultaneously in the following cases 1
1st commanding line batch recording, and commanding divided recording to divide into odd and even pixels when the set value is exceeded
(G) a memory counter for counting the remaining amount of the buffer memory, and (h) when the remaining amount of the buffer memory is large, one of the odd pixel and the even pixel is recorded first, and the other is then recorded. 1 line division recording is instructed, and when the remaining amount of the buffer memory is small, the line for ignoring even pixels and recording only odd pixels and the line for ignoring odd pixels and recording only even pixels are set alternately. Second determination means for instructing the checkered pattern division recording to be recorded and (i) 1-line batch recording by the first determination means is given priority,
The recording mode switching means for switching the recording mode in response to the command for the 1-line divided recording or the checkered pattern-shaped divided recording by the judgment means, and (j) the thermal head when the 1-line batch recording or the 1-line divided recording is performed. It is preferable to have a configuration including a power switching unit that supplies normal recording power and increases the recording power supply to the thermal head only during checkered pattern division recording.

[0011]

In this recording method, the recording power source must have the ability to supply recording power to at least half of all heating elements. If it is possible to supply power to just half of all the heating elements, the black pixel rate is less than the set value because the judgment criterion (set value) for batch recording or divided recording is set to 1/2 or less. In the case of, the batch recording can be performed for one line. When the black pixel ratio exceeds the set value, the pixels on one line are divided into odd pixels and even pixels. Then, the maximum black pixel ratio per line is 1/2 for both the odd-numbered pixels and the even-numbered pixels, and it is possible to separately record from the viewpoint of the capability of the recording power supply. Therefore, in the present invention, a line for recording only odd-numbered pixels and a line for recording only even-numbered pixels are set alternately to record in a checkered pattern. As a result, even if the power supply capacity is half that for one line, it is possible to perform high-speed recording by recording once for each line.

By the way, when recording not a solid black manuscript but ordinary manuscripts and figures, it is extremely rare that the black pixel ratio in one line exceeds 1/2 (50%). Therefore, in the case of the present invention, when a pixel signal is input as in the case of reading a normal document, most of the high speed processing is performed by batch recording. Exceptionally, when the black pixel ratio in one line exceeds the set value (for example, when the black pixel ratio is extremely high like a pixel signal from a solid black document), checkered pattern division recording is performed. Since white pixels are included, the recording quality is slightly degraded, but it can be processed at the same high speed as batch recording.

Although the black pixel ratio of one line exceeds the set value, it is 1
If it is much smaller than the above, the black pixel ratio when divided into odd pixels and even pixels is much smaller than 1/2. In that case, there is a margin in the capacity of the recording power source. If more power is supplied by using this, the amount of heat generated by each heating element of the thermal head will increase, and in the case of thermal recording, the area of the black dots recorded will increase. In this case, the uneven recording is reduced and the recording quality is improved. The recording quality of the checkered black solid portion of the above method is similar to that of a black solid portion of a photograph such as a newspaper or a magazine in which halftone dots are superimposed, and can be used without any trouble in recognition of contrast.

In the case of a facsimile machine, normally,
In many cases, a pixel signal is once stored in a buffer memory for received data and then recorded for each line of pixel data. Since the high-speed recording process is required when the remaining amount of the buffer memory is small, the checkered divisional recording as described above is effective when there are many black pixels. When the remaining amount of the buffer memory is large, it is not necessary to decrease the transmission speed even if the recording speed is decreased. In that case, it is preferable not to deteriorate the recording quality. Therefore, according to the present invention, in such a case, it is possible to satisfy both requirements by separately recording the odd pixel and the even pixel for one line.

[0015]

FIG. 2 is a flow chart showing an embodiment of the recording method according to the present invention. This recording method is a method in which a pixel signal once stored in a buffer memory is supplied for each line to a thermal head in which a large number of heating elements corresponding to the number of pixels for one line are arranged and recorded. First, black pixels are counted from the number of pixels for one line, and the black pixel ratio is compared with a set value (here, 1/2). Black pixel rate is 1/2
In the following cases, one line is collectively recorded, and one line of paper is fed for recording the next line. When the black pixel ratio exceeds 1/2, the odd-numbered pixels and the even-numbered pixels are separately recorded. At this time, when the buffer memory remaining amount exceeds a certain number (that is, when the memory remaining amount is sufficiently large), the odd pixel is recorded for one line, the even pixel is recorded for the same line, and the recording of the next line is performed. In order to do so, one-line divided recording is performed in which the paper is fed by one line. In this case, the recording speed of the recording of one line is slow because it takes about twice as long as the one-line batch recording. On the other hand, when the remaining buffer memory is within a certain number (that is, when the remaining buffer memory is small),
Since the recording speed is slow in the one-line division recording, the buffer memory becomes full and the transmission speed of the pixel signal on the transmission side must be reduced. Therefore, when the black pixel ratio exceeds 1/2 and the buffer memory remaining amount is small, there are a line for ignoring even pixels and recording only odd pixels, and a line for ignoring odd pixels and recording only even pixels. The checkered pattern division recording is performed by alternately setting and recording. As a result, the recording speed becomes the same as the one-line batch recording, and the state in which the buffer memory is full is avoided without reducing the data transmission speed. However, if the checkered pattern division recording is simply performed, even in the case of solid black recording, for example, white pixels exist between each black pixel, and the recording quality deteriorates. Therefore, the power supply amount per pixel is increased, the recording range of one pixel is enlarged, and the white portion is reduced. In order to print in a checkerboard pattern, the paper is fed by one line between the printing of the lines that record only odd pixels and the lines that record only even pixels. In this way, a solid black original or the like can be recorded at high speed without significantly deteriorating the recording quality.

FIG. 3 shows an embodiment in which the recording apparatus according to the present invention is applied to a facsimile apparatus, and is a block diagram of a receiving section of the facsimile apparatus. The data sent from the sending facsimile machine through the telephone line is NC.
Input to the modem 14 via the U (network control device) 12.
The NCU 12 is a telephone line interface, and the modem 14 demodulates the received analog signal into an original digital signal. This received data is temporarily stored in the buffer memory 16. The memory counter 18 counts the remaining buffer memory. The decoding unit 19 decodes the signal from the buffer memory 16. The decoding unit 19 uses the MH method (Modified H
uffman method) to restore the compressed data to the original data. This is once stored in the line memory 20. The line memory 20 can store data for a plurality of lines. The parallel / serial conversion unit 22 converts the output from the line memory 20 into a serial pixel signal and sends it to the 1-line counter 24 and the control circuit 40. The 1-line counter 24 counts the number of pixels for one line, and the black-pixel counter 26 counts the number of black pixels in the line and sends it to the control circuit 40. Further, data is sent from the 1-line counter 24 to the odd pixel memory 30 and the even pixel memory 32 from the selection unit 28 that divides the pixel signal into the odd pixel and the even pixel. Then, the odd pixel and the even pixel are sent from the odd pixel memory 30 and the even pixel memory 32 to the control circuit 40.

The control circuit 40 includes a first judgment means 42, a second judgment means 44, a device control section 47 having a recording mode switching means 46, a thermal head control section 49 having a power switching means 48, and a paper feed motor control. Unit 50, transmission control unit 5
It consists of two. The number of black pixels counted by the black pixel counter 26 is input to the first determination means 42, and one line is collectively recorded from the number of black pixels, or an odd number /
It is determined whether or not the even-numbered pixels are divided and recorded, and in the case of one-line batch recording, the recording mode switching means 4 of the device control unit 47.
6 is sent to the second determination means 44 in the case of division recording.
Send a command to. The remaining amount of the buffer memory 16 counted by the memory counter 18 is input to the second determination means 44,
Depending on the remaining amount, the odd-numbered pixels are recorded for one line, and then the even-numbered pixels are recorded in one-line division recording, or the line for recording only the odd-numbered pixels and the line for recording only the even-numbered pixels are alternated. It is determined whether the checkered pattern division recording to be set and recorded is performed, and the recording mode switching means 4
Send command to 6. The device control unit 47 uses the thermal head 5
6, a thermal head control unit that controls energization to 6, and a paper feed motor control unit 50 that sends a paper feed pulse to the motor 57.
And a transmission control unit 52 that controls the data reception speed.

In the case of one-line batch recording, one line is collectively recorded by the pixel signal from the parallel / serial conversion section 22. At this time, the paper feed motor control unit 50 drives the motor 57 to feed the paper every time one line of recording is completed. An example of the recording state of pixels is shown in FIG. 4A.

In the case of 1-line division recording, first, odd pixel data is sent from the odd pixel memory 30 to the thermal head controller 49 for recording, and then even pixel data is transferred from the even pixel memory 32 to the thermal head controller 49. Send out and record the same line. Then, a recording end command is sent from the device control unit 47 to the paper feed motor control unit 50, and the paper is sent to the next recording line (see FIG. 4B). Therefore, in this case, it is necessary to drive the thermal head twice for recording one line.

In the case of checkered pattern division recording, odd-numbered pixel data is sent from the odd-numbered pixel memory 30 to the thermal head controller 49 to record one line. Here, a command is sent from the device control unit 47 to the paper feed motor control unit 50,
The paper is sent to the next recording line. On the other hand, the pixel data of the next line is input to the odd pixel memory 30 and the even pixel memory 32. The even pixel data of the next line is sent from the even pixel memory 32 to the thermal head controller 49 to record one line. At this time, the power switching means of the thermal head controller 49 increases the power supplied to the heating element. The recording range is expanded compared to normal power supply,
Since the unrecorded portion is reduced, the recording quality is improved (see FIG. 4C).

[0021]

As described above, according to the present invention, the number of black pixels for one line is counted, and when the line where the black pixel ratio exceeds the set value of 1/2 or less continues, only odd pixels are recorded. The checkered pattern division recording is performed by alternately setting the lines and the lines for recording only even pixels, and when the black pixel ratio is less than or equal to the set value, one line batch recording is performed. High-speed recording is possible while suppressing the capacity of the power supply for use.

In the case of checkered pattern division recording, by switching the electric power supplied to the heating elements of the thermal head so as to be increased within an allowable range, the recording range of one pixel is expanded and the recording quality can be improved. If the facsimile device has a buffer memory for received data, check the remaining amount and if the remaining amount is large, switch to 1-line division recording instead of checkered pattern division recording. A high recording quality speed can be maintained and an increase in the capacity of the recording power supply can be suppressed while preventing a decrease in transmission speed. Therefore, according to the present invention, the power source does not become large, the cost is low, and high-speed recording is possible as a whole.

[Brief description of drawings]

FIG. 1 is a basic flowchart of the method of the present invention.

FIG. 2 is a flowchart showing an embodiment of a recording method according to the present invention.

FIG. 3 is a block diagram showing an embodiment of a receiving section of a facsimile apparatus using the recording apparatus according to the present invention.

FIG. 4 is an explanatory diagram for recording pixels according to the present invention.

[Explanation of symbols]

 16 buffer memory 18 memory counter 26 black pixel counter 28 means for selecting odd and even pixels 30 odd pixel memory 32 even pixel memory 42 first judging means 44 second judging means 46 recording mode switching means 48 power switching means

Claims (4)

[Claims] 1. A method of supplying and recording an image signal to a thermal head in which a large number of heating elements corresponding to the number of pixels of one line are arranged to record, and black pixels are counted from the pixel signals of one line to obtain black pixels. When the ratio is less than the set value (1/2 or less), one line of pixels are simultaneously recorded to perform one-line batch recording, and when the line where the black pixel ratio exceeds the set value is continuous, one line is recorded. Pixel is divided into an odd pixel and an even pixel, and a line for ignoring the even pixel and recording only the odd pixel and a line for ignoring the odd pixel and recording only the even pixel are alternately set and recorded. A recording method characterized by performing divided recording. 2. The recording method according to claim 1, wherein when the divided recording is performed in a checkerboard pattern, the electric power supplied per pixel is increased according to the margin of the power supply capacity to perform the thermal recording. 3. A pixel signal to be recorded is temporarily stored in a buffer memory, and the pixel signal is sequentially supplied to a thermal head. When the black pixel ratio of one line exceeds the set value, the pixels of one line are recorded. When the remaining amount of the buffer memory is large by dividing into the odd number pixel and the even number pixel, one line divided recording is performed in which one of the odd number pixel and the even number pixel is recorded first and then the other is recorded, and the remaining amount of the buffer memory is small. 3. A checkered pattern division recording in which a line for ignoring even pixels and recording only odd pixels and a line for ignoring odd pixels and recording only even pixels are alternately set and recorded at this time.
Recording method described. 4. A recording device equipped with a thermal head in which a large number of heating elements corresponding to the number of pixels for one line are arranged and a buffer memory for temporarily storing the received pixel signal, wherein the pixel signal for one line is an odd number. A selection means for dividing the pixel into an even pixel, an odd pixel memory and an even pixel memory for separately retaining the selected odd pixel and even pixel, a black pixel counter for counting black pixels from a pixel signal for one line, and a black pixel When the pixel ratio exceeds the set value (1/2 or less), command 1-line batch recording to record 1-line pixels at the same time. First determination means for instructing divided recording to be recorded separately, a memory counter for counting the remaining amount of the buffer memory, and a case where divided recording is determined by the first determination means. In this case, according to the output of the memory counter, when the remaining amount of the buffer memory is large, one-line division recording is instructed to record one of the odd pixel and the even pixel first and then the other, and When the remaining amount is small, the checkered pattern division recording is instructed in which lines for ignoring even pixels and recording only odd pixels and lines for ignoring odd pixels and recording only even pixels are alternately set 2 determination means and 1-line batch recording from the 1st and 2nd determination means,
Recording mode switching means for switching the recording mode in response to a command for line division recording or checkered pattern division recording, and for 1-line batch recording or 1-line division recording, the thermal head is supplied with normal recording electric power. A recording apparatus having a power switching unit for increasing the recording power supply to the thermal head only when pattern-shaped divided recording is performed.