JPS60107973A - System for reducing uneven feeding at white skip print - Google Patents

Abstract

PURPOSE:To decrease feeding errors and to reduce uneven feeding by changing continuously the speed of a pulse motor and also printing a block print in a predetermined timing while being skipped at the same time. CONSTITUTION:Lines l1-l6 are stored in a picture memory circuit 301, the number of prints per line of the lines l1-l6 is judged by a black picture element detecting circuit 303 and stored in a print number storage memory 305. The time given per one line of a pulse motor is a product between the print number of times of one line and a print time of one block, a histogram circuit 331 generates a histogram corresponding to the print number of times per one line and a continuous variable subscanning control circuit 306 changes the speed of the pulse motor based thereupon. Furthermore, the time given to the pulse motor per one line is controlled by increasing or decreasing the speed by one block time depending on whether the histogram stored at each print time of one block to be minimized or maximized.

Description

[Detailed description of the invention] (a) Technical field to which the invention pertains Book 11? , No. 111 relates to the printing power type of facsimile machines, and more specifically, in a method in which the speed of a pulse motor is continuously changed according to the printing time of one line,
This invention relates to a method for reducing feeding unevenness by continuously changing a pulse motor and printing at a predetermined timing while skipping block printing at the same time.

(b) Printing used in prior art facsimile machines is performed line by line. The line for jlE is printed in such a way that the number of dots in one line is divided into several blocks, and the area where both the dot side and the block τill are active is printed.
Et is printed next.

When driving a print head having the configuration shown in FIG. 1, the signals -8ii are sequentially sent to the shift register 121, and when 1942 minutes have been input, they are latched into the launch registers 115-120. Lunched 11
No. 6 is driven by driver circuits 109 to 114. In order to print the corresponding dots, the HAFLOCK $111 driver is simultaneously driven sequentially to print one line.However, in this case, the dots are sequentially driven regardless of the image information, so even if the image is Even if the block is white, it takes time to print all the blocks. Conventionally, in order to improve this problem, block skip printing has been used in which printing is performed according to the number of black pixels that enter one line, and in this case, the time for one line is:
Since it changes depending on the number of blocks to be printed, the feed speed in the sub-scanning direction also changes accordingly.

The sub-scanning feed using the conventional block-skip force type will be explained below with reference to FIG.

In Figure 2, one block is 288 dots, and 6
A black pixel detection circuit 1 which counts the number of black pixels and prints the blocks up to the point where the black pixels become a dot in the number of simultaneously printed black pixels.
22, and a control circuit 123 that controls the number of print blocks and controls the pulse motor according to the information.

As shown in Figure 2, in line IS, one line was completely black, so it was printed in blocks ■, ■, ■, ■, ■, 00 cells, and in line It, it was printed from blocks ■ to ■, ■. When the blocks ■, ■, and 0 are all black, the blocks ■, ■, and ■ are printed at the same time, and the blocks ■, ■, and ■ are printed in order. In Linem, blocks ■, ■ become dots, blocks ■, ■ become dots, blocks @, ■ become dots, blocks ■, ■, blocks ■, ■, block ■.
,■ and F11 characters at the same time. The problem at this time is that the speed in the scanning direction changes dramatically depending on the number of blocks to be printed. Therefore, the pulse motor used for this must have a high self-starting frequency.

Furthermore, when looking at the printing of the same block number, 11;5, the line pitch is not constant. This causes uneven feeding in the sub-scanning direction.

For example, the error in the pitch between the centers of the printed characters in the block (2) on line 12 and the block (2) on line 12 in FIG. 2 is given by the pitch between the lines being l. Normally, the permissible feed error in facsimile is said to be within 125%1, so this method results in image quality with a lot of uneven feed.

(C) Object of the Invention The present invention has been made in consideration of the above-mentioned conventional situation.1 Therefore, the object of the present invention is to alleviate the above-mentioned drawbacks and to reduce the feed error to within 125% at the maximum. The purpose of the present invention is to provide a new method for reducing uneven feeding.

(d) Structure of the Invention In order to achieve the above object, the method for reducing unevenness in feed during white skip printing according to the present invention is provided with an image signal memory in front of the recording circuit 11, and the image signal memory is stored in the image signal memory. The black vJA elements of each blurred line are counted in block order, and the blocks until the total value of black pixels satisfies the number of black pixels for simultaneous printing are printed simultaneously, and the other blocks are printed sequentially. Create a histogram of the number of block printing times, and continuously change the sub-scanning speed according to the maximum and minimum of the accumulated histogram, and change the sub-scanning speed every one block printing time at most. The printing timing is configured such that the simultaneous printing block and the sequential printing block are printed at a predetermined timing regardless of whether the block is printed or not.

That is, in the present invention, in a method in which the speed of the pulse motor is continuously changed according to the number of black blocks to be printed according to the amount stored in the previous IiC image number memory, the speed of the pulse motor is continuously changed. When the pulse motor is changed only every 1 block printing time even if the change is large, when the block printing is less than the total printing time of that block among the accumulated lines, the specified block printing timing The printing timing of the block is determined so that it is printed at .

(e) Principle and operation of the invention When the sub-scanning speed is continuously changed in combination with white block skip, the present invention stores each image signal in the image signal memory provided immediately before the recording circuit. A histogram of the number of printing times of a line is determined by determining whether the number of simultaneously printed dots is filled, and the sub-scanning speed is changed according to the information.

Simultaneous Trap This is an attempt to reduce unevenness in feed by executing printing at predetermined timing.

(f) Embodiment of the Invention A preferred embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 3 is a block diagram showing one embodiment of the present invention. At the same time as lines 2 to 16 are stored in the image signal memory circuit 301 shown in FIG. The information is stored in the memory 305.

The time given to one line of the pulse motor is (1
It is the product of (number of times a line is printed) and (printing time of one block).

At this time, when the continuously variable sub-scanning control circuit 306 continuously changes the speed of the pulse motor, the histogram circuit 331 generates a histogram of the accumulated number of printing times per 12 inches of the line. This histogram circuit 331 can be configured by, for example, a counter and a memory. To calculate the number of times of printing when creating this histogram, first block 1 and then block 2 are used to judge whether the number of simultaneously printed dots is a pixel or not, and if it is not k pixels, add another block 2 to determine the number of pixels. If the following is true, blocks ■ and ■ are determined to be printed simultaneously. If this is not the case, the block (2) is further added to determine whether it becomes a pixel, and the same determination is made. In this way, the number of simultaneously printed dots is determined in order from block ■,
After that, the number of times is calculated as the sequential printing timing.

1 given to the pulse motor according to this histogram
At the line time, the pulse motor change within FLL is at most 1
For each block printing time, if the histogram stored in the histogram tends to the minimum, it is made faster by one block time, and conversely, if it goes to the maximum, it is made slower by one block time, and so on. Controls the time given to the motor.

In the full length example, the maximum accumulated is 6 blocks of line lx, and hv, R small is 1 block of line 16.

Therefore, when changing one line time of the pulse motor by one block time from line ll, the timing of the print block when changing the pulse motor like this is as shown by the dotted line in Figure 5. Since the change in time given to printing results in a change in the length of one block,
As shown in Fig. 4, line 11 is 6 blocks, line
Q is 5 blocks, line 13H 4 blocks, etc.
...... Line 161 is the time for one block, but the printing timing of each block is changed to line 12.
Now, be sure to print blocks ■ and ■ at the same time, and print blocks ■
Assign the timing so that , ■, ■, ■ are printed on the JVQ. Similarly, for line 15, blocks ■, ■, ■
be sure to print at the same time, and print the remaining blocks ■, ■, ■.
If the timing is determined in this way and the number of times one line is printed as shown in Figure m5, for example, and the printing is performed as described above, the printing will be as shown by the solid line in Figure 4. In this way, when printing each block at the specified timing, the difference in pitch between blocks on each line is
As shown in the table, the maximum is 25%.

Table 1 In Figure 4 and Table 1, N is the number of blocks to be printed separately, An ij is the pitch when looking at the adjacent line + 111 blocks as the center, and Bn is the distance between the same blocks in the worst case. Each pitch is shown below.

In this embodiment, the simultaneous printing blocks are grouped together from the first block based on the simultaneous printing timing of the printing blocks.
It goes without saying that there is no problem in implementing the gravity method even if the blocks are printed all at once starting from the latter half of the blocks.

(2) Effects of the Invention As explained above, the present invention has the effect of reducing feeding unevenness when white block skip printing is performed while continuously variable sub-scanning is performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional recording circuit of this type.
FIG. 2 is a diagram showing print timing and sub-scan feed timing in a conventional recording circuit, FIG. 3 is a block configuration diagram of a recording circuit in an embodiment of the present invention, and FIG. 4 is a diagram showing the printing timing in an embodiment of the present invention. Timing of the recording circuit and sub-scan feed timing diagram. FIG. 5 is a diagram showing a hinutogram of the number of times of printing of the l line in the recording circuit according to the present invention. 101.323・φ・Record printing part, 102.330ψΦ
・Block decoder, 103-108.324-329
"-' F.Tsukudriver, 109~114.317~322@proboscis・
Driver, 115-120.310-316 @ 11
11 rough F, 121, 309e em Schiff
) L-shi5 p, 122% 303 ・” ・L'
, 4 pixels] Eruption circuit, 123.30G @--Control circuit, 124.307--'・Pulse motor driver, 12
5.308...Pulse motor, 301--Line memory circuit, 3o2...@Storage lending detection circuit, 3o4...
Picture 1d memory system ji111 circuit, 305... Memo IJ for storing number of prints, 331... hinutogram circuit Patent applicant NEC Co., Ltd. Representative Patent attorney Yutabe Kumagai

Claims (1)

[Claims] A picture signal memory is provided in front of the recording circuit, and the black pixels of each line stored in the picture signal memory are counted in block order until the total value of black pixels satisfies the number of black pixels to be simultaneously printed. A histogram of the number of block printing is created so that blocks are printed simultaneously and other blocks are printed sequentially, and the sub-scanning speed is continuously changed according to the maximum and minimum of the accumulated histogram. When the scanning speed is changed by one block printing time at most, the printing timing is such that the simultaneous printing block and the sequential printing block are printed at a predetermined timing regardless of whether the block is printed or not. A method to reduce feeding unevenness in white strip Φ printing.