JPH0134425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a facsimile transmission apparatus in which the generation time of an image signal is variable and in which a file code is added to code information obtained by encoding the image signal and transmitted.

In facsimile, the redundancy of image signals is suppressed by encoding to efficiently transmit them. In such encoding, the encoding efficiency changes depending on the redundancy of the image signal, and the amount of codes generated per unit time changes depending on the image signal.
For this reason, on the transmitting side, when transmitting codes at a constant speed, the transmission speed exceeds the generation speed of the image signal, making it impossible to properly transmit the codes. Also, on the receiving side, since the recording time of one line is constant, if the image signal is transmitted at a speed exceeding the recording time, recording becomes impossible.

Therefore, in facsimile, a line synchronization signal (hereinafter referred to as EOL) is inserted for each line as shown in FIG. If the number of codes for one line of image signals is small, a necessary number of fill codes are added between the image signal and EOL. This ensures the minimum number of codes required for one line of signals (hereinafter referred to as minimum guaranteed bits). For example, if the image signal generation time on the transmitting side and the recording time on the receiving side are both 10ms/line, the transmission speed is
At 9600 bps, 96 bits are required as the minimum guaranteed bits, and if the sum of the EOL and code is less than 96 bits, a fill code is added for the missing bit. Furthermore, in a typical facsimile, the user does not simply transmit an image signal, but also generates the necessary character information himself, combines the image information and the character information, and then transmits the result. In this case, both the image information and the character information are encoded as an image signal for each line in the main scanning direction, but the generation time of the image signal may differ between the image information and the character information. When determining the minimum guaranteed number of bits, it is necessary to match the slowest generation time, so when the image signal has a fast generation time,
This resulted in the transmission of a large number of file codes, leading to problems such as higher communication costs.

The present invention eliminates such problems, and even if the generation time of the image signal on the transmitting side facsimile changes significantly, the code is always sent out at a constant speed, so that the receiving side facsimile can record normally, and the reduction in transmission efficiency is avoided. It is an object of the present invention to provide a facsimile machine that can add an optimal amount of file codes that can minimize the number of files.

The present invention is characterized by a counting circuit that counts codes and stops counting when an arbitrarily set reference value is reached and indicates that the reference value has been reached, and a counting circuit that performs EOL generation, image signal encoding, and fill code generation. It has a first-in/first-out function that reads the code in synchronization with the writing and transmission timing of the code output by the coding circuit and the code output by the coding circuit, and indicates this to the outside when the internal code amount falls below a certain value. It consists of a memory circuit (abbreviated as FIFO) with
The encoding circuit finishes encoding one line, and
The facsimile uses this counting circuit only when the amount of codes in the FIFO falls below a specified value, and sends out a file code so that the receiving facsimile does not become unable to record.

The present invention will be explained in detail below with reference to Examples.

FIG. 2 shows a block diagram of an embodiment of the present invention, in which 1 is an image signal generation circuit, 2 is an encoding circuit, 3 is a counting circuit, and 4 is a FIFO. The first image signal generation circuit generates an image signal for the second encoding circuit in units of one line.

FIG. 3 is a time chart showing the state of image signal generation from the first image signal generation circuit. The image signal generation circuit 1 indicates to the encoding circuit 2 that there is a request for encoding and an image signal by turning the image signal control signal ON, and indicates the initial state or a request to finish encoding by turning the image signal control signal OFF. show. During the period when the image signal control signal is ON, one line of encoding processing is performed, and during the period when the image signal control signal is OFF, the image signal generation time is
Time is indeterminate and changes.

The encoding circuit No. 2 has the functions of generating EOL, encoding an image signal, and generating a file code, and the generation speed of each code is set to be sufficiently faster than the transmission speed.

The counting circuit 3 has a minimum guaranteed number of bits set to 2, which is determined by the product of the recording time on the receiving side and the transmission speed.
This can be done according to the instructions of the encoding circuit, and 2
When encoding circuit 4 writes codes to FIFO 4, it simultaneously counts the codes written, and when the count reaches the minimum guaranteed bit number set earlier, it is determined that encoding circuit 2 has reached the number of bits. It has a function to indicate and stop further counting.

FIFO 4 writes the code output by the encoding circuit 2, reads the code in synchronization with the transmission timing, and when the internal code amount falls below the specified value, it can indicate this to the encoding circuit 2. This is a memory circuit with a first-in first-out function.

The specified value is the minimum amount of code necessary to prevent the code in FIFO 4 from running out while encoding circuit 2 is performing encoding processing (referred to as an underflow state). 1 in the encoding circuit
The amount of encoded code for a line is determined by the product of the minimum image signal encoding processing time and the transmission speed.

The memory capacity of FIFO 4 shall be greater than the specified value.

Next, the operation of this embodiment will be explained.

When the image signal control signal is turned ON from the first image signal generation circuit to the second encoding circuit, encoding of one line is started. After the encoding circuit 2 instructs the counting circuit 3 to set the minimum guaranteed bit,
Performs EOL generation, image signal encoding, and 4 FIFO
write to. Further, the counting circuit 3 counts the codes written. When the encoding circuit 2 finishes encoding one line, the counting circuit 3 determines whether it has reached the set value, and if it has reached the set value, no fill code is generated, and if it has not reached the set value, Write the file code to FIFO 4 until it reaches 4. Through the above processing, the number of codes for one line becomes greater than the minimum guaranteed number of bits, and the recording time for one line on the receiving side can be guaranteed.

Next, the second encoding circuit determines the image signal control signal, and if it is ON, starts encoding one line.
If it is OFF, the code amount in the FIFO in step 4 is monitored while waiting for the image signal control signal to turn ON, and if the code amount is above the specified value, nothing is done, and when it is below the specified value, a file code is generated. .

This process continues until the image signal control signal is turned ON.

Therefore, even if the image signal generation time fluctuates, the amount of film codes that correspond to the fluctuations will be transmitted, so the amount of film codes generated can be optimized.

As explained above, the present invention performs file code generation using two types of processing, guarantees the recording time on the receiving side, and maintains the transmission speed according to the amount of code generation no matter how the generation cycle of the image signal changes. It is possible to send out an optimal amount of file codes that do not exceed .

[Brief explanation of drawings]

FIG. 1 is a diagram showing the format of a code transmitted by facsimile, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a time chart showing how an image signal is generated. It is. In the figure, 1... image signal generation circuit, 2...
...encoding circuit, 3...counting circuit, 4...memory circuit.

Claims (1)

[Claims] 1. The time at which the image signal is generated changes, the image signal is collectively encoded for each scan, a synchronization signal is inserted for each scan, and the code length of the image signal for each scan is fixed. A facsimile transmission device that does not have a synchronous signal, and an encoding circuit including an element that generates a code for the synchronization signal, an element that encodes the image signal and generates an image signal code, and an element that generates a file code; a counting circuit that counts the generated codes, stops further counting when the counted value reaches a predetermined reference value, and indicates to the encoding circuit that the counted value has reached the reference value;
A first-in-first that writes the code generated by the encoding circuit, reads the written code in synchronization with the transmission timing, and indicates when the internal code amount becomes less than a specified value. and a memory circuit having an out function, and if the count value of the counting circuit does not reach the reference value after one scan of encoding is completed, the encoding circuit continues to read the count value of the counting circuit until it reaches the reference value. A facsimile transmission characterized in that the file code is generated and the file code is generated when the next image signal is not generated and the internal code amount in the memory circuit becomes less than the prescribed value. Device.