JPS5919664B2 - Sub-scanning method of facsimile transmitter - Google Patents

Description

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

Conventionally, in a facsimile machine using redundancy reduction encoding technology, the number of encoded bits generated per line is small in simple parts of a document, and is not constant in complex parts.

Therefore, in order to transmit coded signals at a constant transmission speed, it is necessary to smooth out the amount of coded signals generated over time. was configured to do so. Therefore, there were the following drawbacks. 1. It is difficult to increase the speed of sub-scanning because reading cannot be performed until the step response of starting and stopping is stabilized.

2. The transmission system such as gears, the transmitted document, etc. vibrate as the device starts and stops, generating noise.

3. Feed unevenness occurs due to disturbances in step response due to load fluctuations, etc.

This invention was made in order to eliminate the above-mentioned drawbacks. N sub-scanning speeds are set in advance, and one of the N sub-scanning speeds is selected depending on the number of encoded bits generated. and without stopping sending originals, etc.
This allows continuous sub-scanning.

This invention will be explained in detail below. In a facsimile that uses redundancy reduction encoding technology, the number of encoded bits generated for each line differs as described above, so the transmission time for one line varies.

Therefore, it is necessary to set the sub-scanning speed to a value commensurate with the transmission time. FIG. 1 is a diagram showing a general example of the sub-scanning speed of the present invention, in which the number of encoded bits per line B,
..., VsNCline/sec to correspond to BsNCbiO]
Determine in advance.

Here, Bs1<Bs2<...<B5N, V5
1>V52...>V5N) The minimum sub-scanning speed VsNCline/sec] is determined by the equation (1) based on the maximum transmission time of one line TsmaxCsec/line]. Here, the maximum transmission time for one line T8max
is the maximum number of encoded bits BC! of one line of image signal. 0v in r (--'C>(1V1ノ}》555Cl.A transfer J1 feed rate FCbit/Sec)] is determined by the equation (2).

Next, the maximum sub-scanning speed Vs, [1ine/SeO] is determined by the minimum transmission time TSmiO[Sec/1ine] for one line by the equation (3). Here, the minimum transmission time Tsmin for one line is the minimum number of encoded bits for one line BSmiO [Bit/1
ine] (0 x BSmin≦Bsi) and the transmission speed f, it is determined by equation (4).

−′ 8. SIA ~ As described above, the sub-scanning speed Si is set in advance to correspond to the number of encoded bits of one line B8l, and in the range where the number of encoded bits of one line Bs is BS(11) x Bs≦81, Select sub-scanning speed Vsi.

It is assumed that the number of encoded bits Bs includes a synchronization signal for each line. FIG. 2 is a block diagram of an apparatus for explaining an embodiment of the present invention, 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, 6
1 is an encoding circuit, 7 is a buffer memory, 8 is a modem, 9 is an encoding bit number detection circuit, 10 is an encoding bit number detection signal, 11 is a sub-scanning control circuit, 12 is a sub-scanning speed control signal, and 13 is a sub-scanning , a drive circuit, and 14 a sub-scanning motor. Next, the operation will be explained.

The transmission document 1 is pinched by rollers 2 and pinch rollers 3 and sent at a preset sub-scanning speed, and the portion to be scanned is irradiated with a light source such as a fluorescent lamp (not shown) to scan The reflected light is reduced in size by the imaging lens 4, and is received by the photoelectric conversion section of the reading element 5 to generate an image signal. After the image signal is encoded by the encoding circuit 6, it becomes an encoded signal,
The data is sent to the buffer memory 7, and further sent to the modem 8, where it is sent out to the transmission line at a constant transmission rate.

Here, since the number of encoded bits generated from the encoding circuit 6 for each line changes as described above, the transmission time required for one line also changes. Therefore, it is necessary to set the sub-scanning speed to a value commensurate with the transmission time. Therefore, the encoded signal from the encoding circuit 6 is sent to the buffer memory 7 and also to the encoded bit number detection circuit 9. The encoded bit number detection circuit 9 detects the number of encoded bits generated for each line. Then, a coded bit number detection signal 10 indicating the detected number of coded bits is sent to the sub-scanning control circuit 11.

As shown in FIG. 1, when the number of encoded bits becomes large, the sub-scanning control circuit 11 reduces the sub-scanning speed (per unit time) so that the arrival time to the next scanning line becomes long. Also, when the number of encoded bits is small, the sub-scanning speed is increased so that the time required to reach the next scanned line is reduced (the number of encoded bits generated per unit time v) is increased. increase the number of bits), buffer memory 7
In order to prevent underflow and overflow of the sub-scanning speed control signal 1, a sub-scanning speed control signal 12 corresponding to the number of encoded bits is set in advance.
2 is sent to the sub-scanning drive circuit 13. Sub-scanning drive circuit 1
Reference numeral 3 drives the sub-scanning motor 14, and the roller 2 and pinch roller 3 feed the transmission original 1.

Therefore, by setting N sub-scanning speeds in advance, the sub-scanning speed of the next line can be determined depending on the number of encoded bits of the previous line, and the amount of generated encoded signals can be determined. It becomes possible to smooth out temporally.

3A and 3B are functional explanatory diagrams of the embodiment shown in FIG. 2, with FIG. 3A showing changes in the sub-scanning speed, and FIG. 3B showing changes in the sub-scanning position.

Both horizontal axes indicate time, and numbers 1 to 5 indicate speed. Third
As can be seen from the figure, in the present invention, recording is performed while the recording paper is moving.

As shown in FIG. 3a, when the number of encoded bits for one line is small, a high sub-scanning speed is used, and when the number of encoded bits is large, a small sub-scanning speed is used. and,
Depending on this sub-scanning speed, the sub-scanning position also changes as shown in FIG. 3b. In this case, if there is a sudden change in the sub-scanning speed, there will be an effect of inertia, but since continuous recording is performed, the effect is less than in intermittent feed. In addition, Fig. 3b (7I)L
indicates the displacement of one line. Note that in this invention, the number of encoded bits is detected and the sub-scanning speed is selected; however, the encoding method used is not limited to a one-dimensional encoding method, and a two-dimensional encoding method may also be used. good.

Further, in the above description, the number of encoded bits is detected for each line, but it goes without saying that directly detecting the transmission time required for each line is completely equivalent to detecting the number of encoded bits.

Furthermore, it is natural that the sub-scanning may be temporarily stopped depending on the capacity of the buffer memory. As established above, this invention sets N sub-scanning speeds corresponding to the transmission time required for one line in advance, and
Since the number of encoded bits generated for each line is detected and one of N sub-scanning speeds is selected, smooth operation can be achieved without stopping sub-scanning.

Therefore, it is possible to reduce the noise, speed up, and increase the accuracy of sub-scanning in facsimile using redundancy suppression coding technology, and furthermore, it is possible to reduce uneven feeding and improve image quality. It has the advantage of being able to

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a general example of the sub-scanning speed of this invention, FIG. 2 is a block diagram of an apparatus for explaining an embodiment of this invention, and FIGS. 3A and 3B are diagrams showing the embodiment of FIG. 2. FIG. 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 is an encoding circuit, 7 is a buffer memory, 8 is a modem, 9 is an encoding bit number detection circuit, 10 is an encoding bit number detection signal, 11 is a sub-scanning control circuit, 12 is a sub-scanning speed increasing signal, 13 is a sub-scanning drive circuit, and 14 is a sub-scanning motor.

Claims (1)

[Claims] 1 An encoding circuit that encodes the read image signal, a buffer memory that stores the encoded signal from this encoding circuit, and a sub-scanning motor that is used as a drive source to perform scanning in a direction perpendicular to the main scanning direction. A sub-scanning mechanism, a sub-scanning control circuit that controls the sub-scanning motor, and a sub-scanning drive circuit that drives the sub-scanning motor in accordance with a sub-scanning speed control signal sent from the sub-scanning control circuit. In a facsimile transmitter, the minimum sub-scanning speed is set in advance to correspond to the maximum transmission time of one line, the maximum sub-scanning speed is set in advance to correspond to the minimum transmission time of one line, and the minimum sub-scanning speed and maximum sub-scanning speed are The sub-scanning speed is divided into (N-1) and N sub-scanning speeds are set, and one of the N sub-scanning speeds is selected depending on the number of encoded bits generated for each line. A sub-scanning method for a facsimile transmitter, characterized in that reading is performed while continuously driving the sub-scanning motor.