JPS6028470B2 - Facsimile sub-scanning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a facsimile sub-scanning method using redundancy suppression coding technology.

Conventionally, in a facsimile machine using redundancy reduction coding technology, the number of coded bits generated in one line is not constant; it is small in simple parts of a document, and increases in complex parts. Therefore, when transmitting and receiving encoded signals at a constant transmission speed, the generation of encoded signals for each line fluctuates over time, so sub-scanning is configured to be sent intermittently by repeatedly starting and stopping it. Ta. Therefore, there were the following drawbacks. ■ It is difficult to increase the speed of sub-scanning because recording is not possible until the step response of starting and stopping is stabilized.

■ The transmission system such as gears, the transmitted document, etc. vibrate with the start and stop operations, and noise is generated.

■ Feed irregularities occur due to disturbances in the step response of starting and stopping due to load fluctuations, etc.

In order to eliminate these drawbacks, the present invention divides one line of sub-scanning into P blocks, and selects the driving speed of each block of the divided sub-scanning based on the amount of encoded information. The purpose of this is to smooth the sub-scanning drive to reduce noise and increase speed.

This invention will be explained below. FIG. 1 shows an example of setting the driving speed of P divided sub-scans (hereinafter referred to as sub-scan blocks) in the present invention, and shows the number of encoded bits Bi/P generated for each sub-scan block. [bit
/bl ratio k] and the driving speed of the sub-scanning block Vi [bIM
k/sec].

A method of setting the driving speeds of N sub-scanning flocks will be described below. In facsimile, maximum number of encoded bits generated per line Bmax [bit/lin
e] to the minimum value Bmin[bit/li ship/] is determined by the encoding method, the maximum length of the facsimile machine, the transmission time, etc.

Therefore, the maximum number of encoded bits generated for each sub-scanning block is the number of encoded bits of 1 line Bmax [bit/
line] divided by the sub-scanning division number P, Bmax/
It is represented by P [bit/bIMk]. Also, the maximum number of encoded bits generated for each sub-scanning block is calculated from the minimum number of encoded bits of one line Bmin [bit/li ship].
It is approximately represented by n/P [bit/block]. Here, the driving speed of the sub-scanning blocks is
The maximum sub-scanning block drive speed V, [block/sec], the minimum sub-scanning block drive speed VN [block /sec] are shown by the following formulas {1) and '2', respectively.

V, = f・P no Bmin [block/sec],
．． ．． ．． ．． ．． [1}VN=f・P/Amax[bIMk/
sec]. ．． ．． ．． ．． ．． ■Also, drive speeds V2, V3, ..., V(N
-, ) settings take into account the tracking characteristics of the mechanical system, and even if the drive speed of the sub-scanning block changes by one step (V, → (...) or Vi → V (i-,)), smooth sub-scanning can be achieved. It is only necessary to set the driving operation so that the driving operation can be realized, there is little unevenness in feeding, a certain level of image quality can be obtained, and no noise or the like is generated. FIG. 2 shows an embodiment of the present invention applied to a facsimile transmitter, in which 1 is a transmission document, 2 is a roller, 3 is a pinch roller, 4 is an imaging lens, 5 is a reading element, and 6 and 7 are Launch memory or block memory (hereinafter referred to as line memory), 8a and 8b are interlocking changeover switches, 9 is an encoding circuit, 10 is a buffer memory, 11 is a modem, 12 is a buffer memory storage bit number detection circuit, 13 is a sub-scanning The control circuit 14 is a sub-scanning motor such as a pulse motor.
Next, the operation of this invention will be explained.

The transmission document 1 is pinched by rollers 2 and pinch rollers 3, and is sent at a preset drive speed for each sub-scanning block. The reflected light of 1 is reduced by an imaging lens 4, and is received by a photoelectric conversion section of a cross-cutting element 5 to generate an image signal. The image signal is temporarily stored in the line memory 6 via the changeover switch 8a. At the same time as the image signal to be stored in the line memory 6 is read, the image signal already stored in the line memory 7 is sent to the encoding circuit 9 via the changeover switch 8b and encoded, and then stored in the buffer memory 0. The data is then sent to the modem 11, and sent out to the transmission line at a constant transmission rate. Further, the line memories 6 and 7 are alternately switched by changeover switches 8a and 8b to determine the end of sub-scanning for one line. Here, since the number of encoded bits generated changes as described above, in order to prevent overflow and underflow of the buffer memory 10, sub-scanning is performed at a driving speed of the sub-scanning block corresponding to the number of encoded bits generated. There is a need.

That is, the P steps of the sub-scanning motor 14 correspond to one line of sub-scanning, and the driving speed of the sub-scanning motor 14 is varied for each step. Therefore, reference values K, , K2 are provided for each buffer memory 1, and the buffer memory accumulated bit number detection circuit 12 is set at the end of driving the previous block.
The number of accumulated bits in the buffer memory 10 is detected, and a buffer memory accumulated bit number signal is sent to the sub-scanning control circuit 13.

The sub-scanning control circuit 13 stores the drive speed pattern of the block shown in FIG. KUK KUK, the drive speed V(i-
.
i+,)<V. <V(;-,)). Here, the values of the reference values K, , K2 are determined by the driving speed Vi of the sub-scanning block, the transmission speed, etc. As described above, depending on the number of accumulated bits in the buffer memory 10, the driving speed of the sub-scanning block can be made one step slower than the driving speed of the previous block, maintained as it is, or made one step farther. By controlling scanning, the generated encoded signal can be temporally smoothed without stopping sub-scanning in principle, and matching with the transmission path becomes possible.

Here, if the reading element 5 is a one-line batch reading method such as a CCD, two line memories (memory of 172 & it for phantom/skin in A4 size) are required, but the image for each sub-scanning block is If signal control is possible, block memory (1728/12=144b if P=12)
It is only necessary to provide two However, if the encoding speed is high, three or more line memories or block memories will be required, and if a two-dimensional encoding method is used, line memory I for reference during encoding will be required.
Books will be added. Further, in the embodiment shown in FIG. 2, a pulse motor is used as the drive source, but other drive sources such as a DC motor may be used. Furthermore, when this invention is applied to a facsimile receiver, if the number of accumulated bits K of the buffer memory 10 is K, SKSK2, contrary to the case of a transmitter, the driving speed Vi of the previous block is maintained as it is, and
If K<K, then select the drive speed V(,) which is one step slower than the drive speed Vi of the previous block, and if K2<K, select the drive speed V(,) which is one step farther than the drive speed Vi of the previous block. By selecting i-,), the same effect as in the case of the transmitter can be obtained.

Also, depending on the capacity of the buffer memory 10,
Naturally, the sub-scanning may be temporarily stopped. Further, in the present invention, since the discussion and recording are performed during the sub-scanning operation, no settling time is required and speeding up can be achieved. FIG. 3 illustrates the relationship between the drive pulse a of the sub-scanning motor 14, the drive speed b of each block, and the sub-scanning position c in the present invention, in the case where 5 steps of the pulse motor are assigned to one line. oc indicates displacement for one line in sub-scanning.

As shown in the figure, one line of sub-scanning is divided into five blocks, and changes in the drive speed of each block are determined by the mechanism system as shown in the block drive speed setting method in Figure 1. The settings are designed to reduce feed unevenness, noise, etc., taking into consideration Smooth operation can be achieved, and lower noise and uneven feed can be expected. In the above embodiment, the selection of the drive speed of the N blocks was changed one step at a time, but the present invention is not limited to this, and if uneven feeding is allowed, it may be changed by two or more steps. Needless to say, this is a good thing.

As explained above, this invention allows one line of sub-scanning to be
Since the sub-scanning blocks are divided into N sub-scanning blocks, the driving speeds of the N sub-scanning blocks are set in advance, and one of the N driving speeds is selected sequentially, the sub-scanning is stopped. Smooth operation can be achieved without any friction.

Furthermore, since any one of the N drive speeds is selected one step at a time, uneven feeding can always be kept below a certain value, and noise can be reduced.

Therefore, it is possible to reduce the noise, speed up, and increase the accuracy of sub-scanning in a facsimile machine that uses redundancy reduction coding technology, and it is also possible to reduce uneven feeding and improve image quality. It has advantages.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of setting the driving speed of a block divided into P blocks according to the present invention, FIG. 2 is a block diagram showing an embodiment when the present invention is applied to a facsimile transmitter, and FIG. 3a to 3c are diagrams for explaining recording examples according to the present invention, FIG. 3a is a diagram showing drive pulses, FIG. 3b is a diagram showing the driving speed of the sub-scanning block, and FIG. It is a figure which shows the displacement of a scan. In the figure, 1 is the original to be sent, 2 is the roller, 3 is the pinch roller,
4 is an imaging lens, 5 is a reading element, 6 and 7 are line memories or block memories, 8a and 8b are changeover switches,
9 is an encoding circuit, 10 is a buffer memory, 11 is a modem, 12 is a buffer memory storage bit number detection circuit, 13 is a sub-scanning control circuit, and 14 is a sub-scanning motor. Figure 1 Figure 3 Figure N Ship

Claims (1)

[Claims] 1. In a facsimile machine that uses redundancy reduction coding technology, one line of sub-scanning is divided into P blocks, and driving speeds of N different blocks corresponding to the number of encoded bits are set in advance, and buffer memory is The reference values K_1, K_2 (K_1≦
K_2) and the number of encoded bits K stored in this buffer memory, and select the driving speed for the next block.
When transmitting, the driving speed is one step faster when 0≦K≦K_1, the same speed as the previous block's driving speed when K_1≦K≦K_2, and one step slower when K_2<K. When receiving, 0≦K When ≦K_1, the driving speed is one step slower, K
A facsimile sub-scanning method characterized by limiting the driving speed to the same speed as the previous block when _1≦K≦K_2, and to one step higher driving speed when K_2<K.