JPS583625B2 - high speed fax machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmission system for transmitting facsimile signals with reduced redundancy in band-compressed facsimile, particularly thermal facsimile.

Among the band compression methods used in thermal facsimile, the block skip method is generally used.

The block skip method divides one main scanning line into a large number of blocks, determines whether or not image information exists for each block, and sets blocks with no image information (i.e., only the base paper of the original) as skip blocks. A block only transmits a skip code indicating that it is a skip block (for example, 1 bit of "0"), and if a block has image information of 1 bit or more (referred to as a skip block), all the image information of that block is transmitted and printed.

This makes it possible to shorten the transmission time for documents with little image information.

In general, facsimiles that use telephone lines for office purposes have a resolution in the main scanning direction of 4 to 6 dots/mm.
A transmission speed of 1000 to 6000 bps is used.

In addition, when the above-mentioned band compression is applied based on a survey of frequently used manuscripts, the total number of bits per line (the sum of the skip code of the skip block and the image information of the non-skip block) is the smallest in one block. It is known that the length on the original is 2-3 mm.

If the resolution is 5.33 dots/mm and the length (number of bits) of one block is 16 bits, the length on the original will be 3 mm and the band compression ratio will be the highest.

Therefore, if a transmission with a speed of 4800 bps is used, it takes 3.33 ms to transmit 16 bits.

However, in the thermal printing method, it takes 5 to 8 ms to print one time, so printing 16 bits at the same time is a waste of time.

Therefore, if two blocks (32 bits) are printed at the same time, the transmission time is 6.67 ms, which is equal to the printing time, so there is no wasted time.

When printing two blocks simultaneously in this manner, since the skip block is located in the middle of one line, it is necessary to notify the receiver side of information regarding which block and which block are to be printed.

Further, the thermal head of the printing section of the receiver is made up of a large number of heat generating resistive elements arranged in a straight line, and the heat generating resistive elements are arranged at a fineness determined by the main scanning resolution.

A current is passed through this heating resistor element, and the generated Joule heat is transferred to the heat-sensitive recording paper for color printing.

The heating resistor element is divided into blocks to reduce the number of terminals and is driven by a diode matrix.

When printing two blocks at the same time, there is a method in which a row of heating resistive elements is divided into two groups, left and right, and each group is driven by a diode matrix.

A block diagram of the printing section of the receiver in that case is shown in FIG.

The facsimile signal 1 is input to shift registers 2 and 3 with serial and manually operated parallel outputs, and the respective outputs are connected to input terminals of shift registers 4 and 5 with parallel input/output.

The outputs of shift registers 4 and 5 cause switches 6-1,
6-2, ......, 6-n and 7-1, 7-
2, . . . , 7-n are opened and closed.

Switch 6-1, 6-2, 6-n
One terminal is grounded and the other terminal is connected to the diode matrix 8.

Switches 7-1, 7-2, 7-n
is likewise connected to ground and to the diode matrix 9.

The diode matrices 8 and 9 each consist of m blocks each including n heating resistive elements 10 as one block.

Each block of the heating resistor element 10 has a switch 11-1.1.
1-2, ......, 11-m, 12-1, 1
2-2, .

The negative pole of the power supply 14 is grounded. switch 11,1
The opening and closing of the openings 2 are controlled by the distribution control circuit 15.

Note that the group of heating resistive elements connected to the diode matrix 8 is called group A, and the group of heating resistive elements connected to the diode matrix 9 is called group B.

Next, the operation of the block diagram in FIG. 1 will be explained.

When the image information of one block belonging to group A is sent from the transmitter side as a facsimile signal 1, the read clock 16 of the shift register 2 is outputted, and the image information of that block is stored in the shift register 2.

Then, the image information of one block belonging to group B is stored in the shift register 3 by the clock 17 as well.

When data is stored in the two shift registers 2 and 3, one clock pulse 18 is output and the data is stored in the shift registers 2 and 3.
data are transferred to shift registers 4 and 5, respectively.

The outputs of shift registers 4 and 5 control switch 6 so that the bit to be printed is closed and the others are open.

In addition, the image information sent from the transmitter as described above includes information about what block in group A it is (for example, x-th) and what block in group B (for example, y-th). is also being sent, the distribution control circuit 15 closes the switches 11-x and 12-y and opens the others.

When the opening/closing settings of the switches 6, 7, 11, and 12 are completed, the switch 13 is closed for the printing time, and the power supply 14 is closed.
The current from switch 13→switch 11→x and switch 12-y
→ Heat generating resistor element → Closed switch among switches 6 and 7 →
Grounding and current, the X-th block belonging to group A and the y-th block belonging to group B perform heat-generating printing at the same time.

In the above description, an example has been shown in which one line is divided into two groups, but it is also possible to divide the line into an arbitrary number of two or more groups and simultaneously print blocks of that number or less.

Next, a specific example of the case where an actual facsimile signal is transmitted and printed in the above example will be described.

FIG. 2 is an explanatory diagram showing a document, block division, group division, etc.

Main scanning is performed on the portion of the document 19 indicated by the arrow 20 from the left to the right in the figure.

A pulse train of waveform 21 is obtained by quantizing the obtained image signal, and the upper level indicates black and the lower level indicates white.

One main scanning line is divided into two groups, group A and group B, as shown in 22, and each group is divided into 12 blocks, and each group is assigned a number from 1 to 12 as shown in 23. do.

Therefore, when specifying a specific block within one line, the group name and block number within the group name are displayed.

Waveform 24 shows the block in which image information exists based on waveform 21.

That is, in group A, image information exists in blocks 4, 5.6, and 12, and in group B, image information exists in blocks 1 to 5, 7.
, 9 and 10 have image information.

On the transmitter side, the data of the waveform 21 is edited so that data transmission and printing are performed in a minimum amount of time.

As is clear from the waveform 24, there are 4 blocks in group A and 8 blocks in group B of one line of image information in the above example.

Here, even if data of different blocks belonging to one group are successively sent, it is impossible to print them at the same time.

Therefore, it is necessary to select blocks so as to span the two groups A and B.

That is, the fourth block from group A and the fourth block from group B are continuously extracted and their image data is transmitted, and the data of the two blocks are printed at the same time.

Next, the fifth block of group A and the second block of group B are similarly taken out, transmitted, and printed.

Continue until all non-skip blocks of the group with the smaller number of blocks (non-skip blocks) in which image information belonging to the group exists are completed.

In this example, group A has 4 blocks and group B has 8 blocks.
Since there is a skipped block, the data is transmitted and printed four times as described above.

Here, for group A, for all skip blocks,
Also, in group B, blocks 1, 2, 3, and 4 were transmitted and printed.

Also, there are 4 skipped blocks left only in group B, but even if you continue to send them 2 blocks at a time, they cannot be printed, so add 4 dummy image information blocks corresponding to group A. Transmit, print.

That is, when transmitting and printing the image information of the fifth block of group B, the arbitrary numbered block of group A and one block's worth of image information having all white content are transmitted and printed together.

In this case, the receiver side can perform printing operations in exactly the same way as in other cases, but group A does not print at all (
Alternatively, it may be considered that one block of white is printed.

). In the above example, dummy information for four blocks belonging to group A is required.

This results in a decrease in the efficiency of band compression and an increase in wasted time.

That is, even if the transmission speed is doubled, the transmission time is not halved.

In order to eliminate the above-mentioned drawbacks, the present invention provides a method for dividing groups so that adjacent blocks belong to different groups.

According to a survey of manuscripts generally used for facsimile transmission, when the image signal of one scan is divided into blocks equivalent to a length of several millimeters on the manuscript, the blocks containing image information (not skipped blocks) are continuous. It is known that in manuscripts in which characters are written horizontally, they are often unevenly distributed on either the left or right side.

When using such a document, if you divide the blocks into two groups, dividing them left and right as in the example in Figure 1 will increase the number of dummy blocks during transmission and printing. If you take out every other block and group them, you can reduce the number of dummy blocks.

FIG. 3 shows the printed section of a receiver according to an embodiment of the present invention, in which a row of heating resistive elements is divided into two groups, odd-numbered blocks and even-numbered blocks, and each group is driven by a diode matrix. It is a block diagram.

The facsimile signal 1 is input to serial input/parallel output shift registers 2 and 3, and the respective outputs are provided by drivers 25 and 2, each consisting of a parallel input/output shift register and a switch.
Connected to 6.

Driver 25, 260 outputs are connected to diode matrices 8, 9, respectively.

The diode matrices 8 and 9 each consist of m blocks each including n heating resistive elements 10 as one block.

Each block of the heating resistor element 10 has a switch 11-1, 1
1-2, 11-3, 11-m, 1
2-1, 12-2, .

The negative pole of the power supply 14 is grounded.

The switches 11-, 12- are connected to each distribution control circuit 15-1,
15-2 respectively control opening and closing.

Note that the group of heating resistive elements connected to the diode matrix 8 is called group A, and the group of heating resistive elements connected to the diode matrix 9 is called group B.

The operation of the block diagram in FIG. 3 is different from that shown in the block diagram of FIG. 1 only in the arrangement, so a description of the operation will be omitted.

Transmitting the actual facsimile IJ signal for the example in Figure 3,
A specific example of printing will be explained using FIG. 2 above.

One main scanning line is divided into 24 blocks as shown at 27, and every other block is divided into group A and the remaining every other block is grouped into group B as shown at 28.

Blocks within each group range from 1 to 1 as shown in 27.
Assign numbers up to 2.

As is clear from waveform 24, in group A, block 3
, 7, 8, 9, 10, and 11 are non-skip blocks in which image information exists, and in group B, six blocks, blocks 2, 3, 6, 7, 8, and 11 are non-skip blocks. be.

Therefore, the third block from group A and the second block from group B are continuously taken out and their image data is transmitted, and the data of these two blocks are respectively input to shift registers 2 and 3 in Fig. 3, and then printed simultaneously. do.

Next, the seventh block of group A and the third block of group B are similarly extracted and processed.

The process continues until all the skipped blocks in the group with the smaller number of skipped blocks belonging to the group are completed.

In this example, the number is the same for groups A and B, 6, so if the above-described transmission and printing is performed six times, the transmission and printing of all non-skip blocks will be completed.

If there is a difference in the number of non-skip blocks belonging to each group A and group B, dummy blocks must be added, as in the conventional method.

However, as is clear from this example, due to the transmission and printing method in which adjacent blocks belong to different groups,
Image information having all-white content that must be added as a dummy can be significantly reduced, and a thermal facsimile machine having twice the speed can be constructed without reducing the efficiency of band compression.

In the above example, the method of dividing one scanning line into two groups was explained, but as shown in FIG. It is possible to assign numbers from 1 to 8 to the blocks, and to extract and print the non-skip blocks one by one from each of the three groups.Furthermore, it is also possible to similarly divide one scanning line into any number of blocks. It is clearly possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the printing section of a conventional receiver, FIG. 2 is an explanatory diagram of block division, etc. in the conventional and the present invention, and FIG. 3 is an example of the printing section of the receiver in the present invention. It is a block diagram. 1...Facsimile signal, 2,3...
Shift register, 8, 9... Diode matrix, 10... Heat generating resistor element, 11-1 to 1
1-m, 12-1 to 12-m...Switch, 1
3... Switch, 14... Power supply, 15
-1, 15-2...Distribution control circuit, 19...
...Manuscript, 20...Arrow, 25, 26...
... Driver, 27 ... Signal block, 2
8, 29...Group of signals, 30...
- Signal block.

Claims (1)

[Claims] 1 means for scanning and photoelectrically converting the original to be transmitted and dividing the image signal for one main scanning line into m blocks; ) a means for performing a sample operation every other block and grouping the blocks extracted by the sample operation; A means for inspecting image information in blocks included in a group to detect blocks containing image information (information other than background), and extracting blocks containing image information obtained by the detection means one by one for each group. and means for transmitting the image signals summarized by the means to a receiving side, and simultaneously printing the transmitted image signals for each of the summarized image signals on the receiving side. high-speed facsimile machine.