JPH0145270B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a facsimile control system, and particularly to a control system for inserting dummy bits into compressed data.

Generally, in facsimile machines, dummy bits (fill bits) are added to the compressed data according to the data compression rate when transmitting encoded data, that is, compressed data, in order to harmonize the reading and recording speed with the transmission speed. It is inserted.

For example, the I/O speed is 20mS/line (A4 size
For fax machines that record 1728 bits/216 mm in 20 mS, set the modem speed to
When transmitting compressed data at 9600BPS, 1
The number of bits that can be sent on a line is calculated using the following formula.

9600×20BPS・mS/l=192BITS (1) When transmitting compressed data with the modem speed set to 4800BPS, the number of bits that can be sent in one line is calculated using the following formula.

4800×20BPS・mS/l=96BITS...(2) If data is transmitted faster than these modem speeds, the recording section will not be able to record it, so the number of bits shown in equations (1) and (2) above Adjustments are made by inserting dummy bits (filter bits) so that

Usually, a synchronization code (EOL) is included in one line.
, data (modifier-Hoffman code), and dummy bits (FILL) are transmitted.

Conventionally, when searching for dummy bits in compressed data, they are inserted into each line as shown in Figure 1a.
FILL is inserted for EOL and DATA. That is, as mentioned above, a certain minimum transmission time per line is determined from the relationship of reading and recording speeds, and if the transmission time for one line of compressed data is shorter than the minimum transmission time, one line is A fill bit is inserted for each line, and the transmission time for each line is guaranteed to be longer than the minimum transmission time.

Therefore, a considerable amount of fill bits must be transmitted while transmitting one page of encoded data, and even if data is compressed, the compression function cannot be utilized.

Therefore, as shown in Fig. 1b, a method has been proposed in which fill bits are inserted every 32 lines at once instead of inserting fill bits every line ((A) Japanese Patent Laid-Open No. 52-48423). Publication, (B) Unexamined Japanese Patent Publication 1983-
(See Publication No. 14767).

Both of these are 20mS x 32 = 640mS/
It is adjusted at the end of the 32 line so that it becomes 32 line.

In the above publication (A), the number of bits is counted for each encoded output corresponding to a predetermined number of scanning line pixel information, and if the result is smaller than a predetermined reference bit based on the sub-scanning time on the receiving side. , insert a file bit.

Further, in the above publication (B), when T ₁ is the recording time of block pixel information on the receiving side and T ₂ is the time required to transmit encoded data after compressing the block pixel information, T ₂ ≧T _1. Insert the file bits so that

However, these conventional control methods use a counter that counts the number of bits for each encoded output corresponding to a predetermined number of scanning line pixel information, or a counter that counts the number of bits received from the number and position of black pixels in block pixel information. In the apparatus, it is necessary to provide means for calculating the time required to record block pixel information.

An object of the present invention is to eliminate these drawbacks by creating a dummy image for each block using a simple method without requiring a special circuit for counting the number of bits or calculating the time to record block pixel information. - To provide a facsimile control system that can insert bits.

The facsimile control method of the present invention includes a buffer memory that temporarily stores pixel information read by a reading device, an encoding means that encodes the pixel information read from the buffer memory for each scanning line, and In a facsimile apparatus having means for adding dummy bits for each predetermined number of scanning lines, and control means for controlling each means,
When the buffer memory no longer contains the read pixel information, the control means controls the buffer memory for a period of time while receiving empty information from the buffer memory.
A feature of the present invention is that it instructs the encoding means to insert dummy bits.

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

FIG. 2 is an operational block diagram of a facsimile control system showing an embodiment of the present invention.

4 is reading and scanning section, 5 is (32 lines)
an input buffer memory having a storage capacity of ×2;
6 is an encoding unit that performs data compression for each line; 7
8 is an output buffer memory, and 10 is a system control unit for controlling each device.

During transmission, pixel information of 32 bits each in the sub-scanning direction output from the reading scanning section 4 is stored in one 32-line memory block in the input buffer memory 5, and is stored in the other 32-line memory block. One line at a time is sequentially taken out from the memory block and output to the encoder 6.

The system control unit 10 outputs a reading scanning command 11 to the reading scanning unit 4, receives sense information 12 from the reading scanning unit 1, and receives sense information 13 from the buffer memory 5, and then outputs a reading scanning command 11 to the encoding unit 6. An encoding start command 14 is sent to the encoder. The sense information 13 includes information indicating whether data in the buffer memory 5 is free or occupied, and the system control unit 10 stores valid data (dummy bits) in both memory blocks of the buffer memory 5. When there is no more readable data (other than readable data), a dummy bit insertion command is sent to the encoding unit 6 for that period, and the dummy bit insertion unit 7 inserts the dummy bits.
Send the bit.

FIG. 3 is an explanatory diagram of each interface signal in FIG. 2, and FIG. 4 is an operational flowchart of the buffer memory.

At the time of transmission, the system control unit 10 outputs a clear signal _S1 to the buffer memory 5 to initialize the internal register, and outputs the transmission mode set signal.
Output S ₂ to set transmit mode. Additionally, the system control section 10 outputs a clear signal _S3 to the encoding section 6 to initialize the status register of the encoding section 6, and outputs a transmission mode set signal _S4 to start the compression operation. output the fill bit control signal _S5 or _S6 .

When the buffer memory 5 and the encoding unit 6 have been initialized, the system control unit 10
starts reading operation in units of 32 lines.

At the same time, the system control section 10 outputs a buffer start signal _S7 to the buffer memory 5, so that one of the 32 lines of memory blocks inside the buffer memory is read by the scanning section 4.
When it is filled with the pixel information S ₈ output from the encoder 6, it outputs a start signal S ₉ to the encoder 6.

When the buffer memory 5 is started in this manner, as shown in FIG. If there is a buffer ready signal S10, the buffer ready signal _S10 is outputted to the encoder 6 (operation 22).

Furthermore, when both memory blocks in the buffer memory are empty and no pixel information _S8 is input from the reading scanning section 4, a buffer empty signal _S11 is output to the system control section 10. (Actions 24, 25).

The system control section 10 includes a buffer
Only during the period when the empty signal S ₁₁ is output,
A fill bit control signal _S5 or _S6 is sent to the encoder 6.

The encoding unit 6 includes a system control unit 10
According to the file bit control signal _S5 from
Instructs bit insertion. During this period, the buffer ready signal _S10 from the buffer memory 5 is no longer output.

The encoder 6 outputs the binary strobe signal S ₁₂ to the buffer memory 5 when the fill bit control signals S ₅ and S ₆ are gone and the output of the buffer ready signal S ₁₀ is turned on. One line of pixel information _S13 is taken in from the buffer memory 5 in synchronization with the clock _S14 . At the same time, an EOL code indicating the line separation is generated. Then, the captured pixel information for one line is encoded and data compressed using the Modified Hoffman method. Then, the next binary strobe signal _S12 is output to the buffer memory 5, and the next line of pixel information _S13 is taken in. In this way, the encoding unit 6 performs _one
Pixel information _S13 is continuously captured line by line and encoded.

On the other hand, the system control unit 10 controls the reading scanning unit 4 to read the 32 lines in a scanning time of 640mS.
After reading 32 lines of data, the reading is interrupted and as a result, there is no valid pixel information in the buffer memory 5. This allows the system
The control section 10 receives a buffer empty signal.
While S ₁₁ is being output, fill bit control signals S ₅ and S ₆ are sent out.

In this way, when all one page of the original is read and the data compression is completed, the system control unit 10 gives an instruction to stop the compression operation (operation 27), generates an EOL code, and starts a series of operations. end.

Note that the decode data go signal S ₁₅ to the buffer memory 5 shown in FIG.
S ₁₆ and an end-of-writing signal S ₁₇ indicating a break between lines are both output during decoding processing.

FIG. 5 is an operation time chart of the reading scanning section.

FIG. 5a is a time chart showing the speed of the carriage of the reading scanning section, and FIGS. 5b, c, and d are time charts showing the detected slit and sub-scan feed.

A reading head, a recording head, and a slit detector are provided on the carriage to detect each slit as the carriage moves.

The carriage is driven from its home position and increases in speed in response to the output from the slit detector, as shown in FIG. 5a, until it reaches a constant speed.

When the carriage reaches a certain speed and the detector detects the slit 12s shown in FIG. 5b, the reading head is driven in response to the slit 12a shown in FIG. I do. As the carriage moves, when it detects the slit 12e, the carriage is decelerated, turns around at the end, and returns to the home position at high speed. During this time, the document is fed in the sub-scanning direction as shown in FIG. 5d.

In this case, if the effective scanning time is small compared to the reading scanning time of 32 lines, that is, if the effective scanning time is
Even if the time T ₂ for actually reading data is shorter than the scanning time, the memory data presence/absence flag is set and reset at the end of the scanning time t ₂ .

The memory data presence/absence flag is
one for each block, and when both are reset, the system buffer memory 5 is
A buffer empty signal _S11 is output to the control section 10.

As explained above, according to the present invention, it is sufficient to simply detect that there is no valid pixel information in the input buffer memory and insert dummy bits for that period. Alternatively, there is no need to provide means for calculating the recording time of block pixel information, and dummy bits can be transmitted for each block using an extremely simple method.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional dummy bit insertion method, FIG. 2 is an explanatory diagram of the operation of a facsimile control system showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram of each interface signal in FIG. FIG. 4 is an operational flow chart of the buffer memory shown in FIG. 3, and FIG. 5 is a time chart of the reading scanning section. 4: reading scanning unit, 5: input buffer memory, 6: encoding unit, 7: dummy bit insertion unit,
8: Output buffer memory, 10: System control unit, 11: Reading scan command, 12,
13: Sense information, 14: Encoding start command,
15: Encoded data transmission command.

Claims (1)

[Claims] 1. A buffer memory that temporarily stores pixel information read by a reading device;
A facsimile device having an encoding means for encoding pixel information read from a memory for each scanning line, means for adding dummy bits for each predetermined number of scanning lines, and a control means for controlling each means. In this case, when the buffer memory no longer contains the read pixel information, the control means sends a dummy signal to the encoding means only during the period of time while receiving empty information from the buffer memory.
A facsimile control method characterized by instructing bit insertion. 2. The facsimile control system according to claim 1, wherein the control unit controls a predetermined reading scanning time of a scanning line to a predetermined time. 3. If the effective scanning time is smaller than the predetermined reading scanning time of the scanning line, the buffer memory
The facsimile control system according to claim 1, characterized in that a data presence/absence flag is set or reset.