JPS5932028B2 - Communication device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a communication device used for transmitting calligraphy signals, etc.
In particular, it relates to a communication device for transmitting written signals as quickly as possible within a limited frequency band by encoding pixel signals.

In general, written signals have a two-dimensional correlation, so if we select nearby pixels as reference points for a pixel of interest and refer to that pattern as a "state," the amount of information for the pixel of interest will vary greatly depending on the state to which it belongs. . FIG. 1 is an explanatory diagram showing the relationship between a pixel of interest and a reference pixel, where X is the pixel of interest, A, B
, C, and D are reference pixels. Figure 2 is an explanatory diagram showing the situation in which the amount of information of It can be inferred that Since the amount of information held by the pixel of interest X varies greatly depending on the state to which it belongs, when encoding this, it is preferable from the viewpoint of information transmission efficiency to encode it in two sequences. Such a method is also used in communication devices.

An example of a conventional device will be described for comparison with the device of the present invention. When a conventional device is divided into two series, each series is called S and W, and the states belonging to each series are called S mode and W mode, respectively.

The signals Ms and Mw of each mode are determined according to the following equation (1). Ms=ABD+ABD, Mw■1-Ms・
...(1) Also, the value of X that occurs frequently in each state
・・・・・・・・・・・・・・・ (2) is determined.

Next, the code assignment format follows, for example, the format shown in FIG.

It is known that the lower the probability of appearance of the order 2m = 1 code in Fig. 3, the higher the value, the better the efficiency.In the conventional device described here, in S mode, 2m = 4
, 2m=2 in w mode. Further, a specific example of the code word is as shown in FIG. FIG. 5 is an explanatory diagram showing the signals of each part of the device when the above-mentioned code words are used to transmit image information. FIG. And the image is white (“
It is represented by a binary signal of 0゛) and black (“1”).

Assume that the bottom row is an address, and pixel information from addresses 1 to 16 is shown. From Figure 5 a, the formula (1
), the mode signal is calculated as Δ as shown in FIG. 5b, and the prediction signal X is calculated as shown in FIG. 5A, c.

Where X and X match, X is determined from X, but where A does not match, the value of the predicted conversion signal Y is set to 1 to indicate that X and X are different.

That is, Y=XeX... (3) However, 4 is a symbol indicating exclusive OR. Therefore, the predicted transformed signal Y shown in FIG. 5 d is obtained from FIG. 5 a (!: c). FIG. These predictive conversion signals are combined into symbols and encoded as shown in FIG. 4. In other words, "00
00” becomes the code word “0”, [01” indicated by S2 becomes the code word “101”, and “00” indicated by Wl, W2, W6
" becomes the code word "O", "1" indicated by W3W5 becomes the code word [10], and "O1" indicated by W4 becomes the code word [11].
” is sent. In this case, in the transmission by the conventional device, as shown in FIG. 6, the signal representing the break in the line is first transmitted, and then the S sequence is encoded, that is, in the example of FIG. Input a signal representing S2 with the code word 0101, then input a signal indicating a change from the S sequence to the W sequence, that is, a signal indicating a mode break,
Next, the signal obtained by encoding the W sequence, that is, in the example of FIG. 5, Wl, W2, W3, W4, W5, W6 is coded as
A signal represented by 01011100 is transmitted.

As described above, the conventional device transmits the writing signal as quickly as possible within a limited frequency band, but the drawback of the conventional device is that the mode cut signal is transmitted as shown in Figure 6. This is a point that needs to be transmitted, and this signal can be transmitted if there are n modes (n-1
) signals, and inserting these signals delays the transmission speed of the drawing signal accordingly.

An object of the present invention is to eliminate the above-mentioned drawbacks of conventional devices and to provide a communication device that does not require transmitting a mode switching signal.

In other words, the device of the present invention transmits signals in an order that allows the receiving side to easily determine the mode without inserting a signal indicating a mode break. The mode switching device controls the output of the encoding device of the sequence to which the unit signal with the smallest address belongs. Therefore, the device of the present invention is the same as the conventional device until the signals shown in FIG. 7th
As shown in the figure, first a signal indicating the line break is transmitted, and then the unit signal that has not been transmitted and has the youngest address is address 1, and the series to which this belongs is S, so the fifth
S1 (addresses 1, 2, 5, 8) shown in FIG. 5e are collectively transmitted as a code shown as S1 in FIG. 5g.

Next is the unsent unit signal, and the youngest address is address 3, so the series to which it belongs is W, and Fig. 5 f
W1 (addresses 3, 4) shown in FIG. 5 are collectively transmitted as the W1 code shown in FIG. 5g. Similarly, Sl
, Wl, W2, W3, S2, . . . are transmitted as shown in FIG. FIG. 9 is a block diagram showing the configuration of a conventional transmitting device for performing the transmission shown in FIG. a distributor that switches the output according to the mode signal and distributes it to the S mode encoder and the W mode encoder, 204;
2 is an S mode encoder, 205 is a W mode encoder, 206 is a memory for S mode code words, 207 is a memory for W mode code words, 208 is a switch, 209 is an address counter, 2
10 is a controller.

A reference line and a line of interest are stored in the address position of the image memory 201 designated by the address signal output from the address counter 209 as shown in FIG. The predictive conversion signal shown in FIG.
According to this mode signal, the predicted conversion signal is distributed as shown in FIG. 207 respectively.

In the example of FIG. 5, the memory 206 contains "O" (S1), "1"
01” (S2), but the memory 207 has “0” (W1),
"O" (W2), "10""W3","11" (W4)
, "10" (W5), and "O" (W6) are stored. After the controller 210 sends out the "line break" signal shown in FIG. 6, it reads out the contents of the memory 206 and sends it out, and when this reading is finished, it sends out the "mode break" signal shown in FIG. , and then reads out the contents of the memory 207 and sends them out.

The transmitter used in the present invention can be easily designed in accordance with the explanations regarding FIGS. 5 and 7 described above, if one has knowledge of the conventional transmitter shown in FIG. 9.

FIG. 10 is a block diagram showing an example of the transmitting device of the present invention. In FIG. 10, the same reference numerals as in FIG. 9 indicate the same or corresponding parts, and 214 and 215 are 204
, 205, 211 and 212 are unencoded address memories of S mode and W mode, respectively, and 213 is a comparator. The signals shown in are encoder 2 respectively.
The operation up to input to bits 14 and 215 is the same as that shown in FIG. Set in encoded address memories 211 and 212.

To explain using the example of FIG. 5, for example, S mode encoder 2
When the encoding of S1 is finished in step 14, the start address 110q of S2 is set in the S mode unencoded address memory 211, and when the encoding of W1 is finished in the W mode encoder 215, the start address 961 of W2 is set. W mode unencoded address memory 212 is set. After the sending of S and W1 is completed (Sl and W are sent in that order because 611 and t23 are set in the address memories 211 and 212 corresponding to S1 and W1, respectively), the address memories 211 and 212 Contents 110I and! 61 and comparator 2
13, the switch 208 is the W mode encoder 21
W2 is sent from 5. When W2 is sent, the W mode unencoded address memory 212 contains the start address W of W3.
9l is set. In this way, memory 2 in FIG.
without requiring memory equivalent to 06,209,
Transmission as shown in FIG. 7 can be performed by controlling the switching of the switch 208 according to the comparison of the unencoded address memories 211 and 212 in the order of encoding by the encoders 214 and 215. FIG. 8 is a block diagram showing a receiving side decoder in an embodiment of the present invention, in which 100 is a buffer memory for received and detected codes, 101 is a decoder changeover switch,
102 is an S mode decoder, 103 is a W mode decoder, 1
04 is an S mode conversion signal memory I8, and 105 is a W mode conversion signal memory.

106 is a readout switch and memory empty detector, 107 is a signal inversion circuit, 108 is a mode determiner, and 109 is a line memory for one line of decoded pixels.

Signals for predictive inverse transformation from the line memory 109, A, B,
C enters the signal inverse conversion circuit 107, and the father is created using equation (2).

Also, from line memo I river 09, signals A, B,
D enters the mode determiner 108, determines the mode according to equation (1), and sends it to the readout switch/memory empty detector 106 where it is output to the S mode conversion signal memory 104.
, W The converted signal Y is read from the memory of the designated mode in the W mode converted signal memory 105. The decoded pixel signal X is processed by the signal inverse conversion circuit 107 as follows:
4) and is output from the terminal 110 at the same time as it is written to the line memory 109. If S mode conversion signal memory 104 and W mode conversion signal memory 105
If the signal of the specified mode cannot be read out by the memory empty, a signal is given to the changeover switch 101,
It is determined that the signal read from the buffer memory 100 is the code word of the requested mode, and the S-mode decoder 10
The decoder of the designated mode, either W mode decoder 103 or W mode decoder 103, operates, and the decoded predictive conversion signal is guided to the memory of the designated mode.

Therefore, the S mode conversion memory 104 and the W mode conversion memory 105 only need to have a memory capacity equal to the number of applied code orders (2 m). As is clear from the above explanation regarding FIG. 8, by sequentially transmitting unit signals starting from the output of the encoding device of the sequence to which the address of the unit signal with the smallest address among the untransmitted unit signals belongs, mode expiration can be achieved. According to the present invention, the modes can be separated by a simple circuit without inserting a signal indicating the mode break. It is possible to obtain a communication device that quickly transmits calligraphic signals.

Further, in the above description, the present invention has been described as being used for transmitting drawing signals, but it goes without saying that the apparatus of the present invention is also effective when transmitting information other than drawing signals.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the relationship between the pixel of interest and the reference pixel, Fig. 2 is an explanatory diagram showing the situation in which the amount of information of X changes depending on the pattern of the reference pixel, and Fig. 3 is an example of the code assignment format. FIG. 4 is an explanatory diagram showing an example of a code word, FIG. 5 is an explanatory diagram showing signals of each part of the device when code words are used to transmit image information, and FIG. FIG. 7 is an explanatory diagram showing a transmission signal of the apparatus of the present invention, FIG. 8 is a block diagram showing a receiving side decoder in an embodiment of the invention, and FIG. 9 is a block diagram showing a conventional decoder. FIG. 10 is a block diagram showing an example of the transmitting apparatus of the present invention.

Claims (1)

[Claims] 1 A mode selection circuit that selects one of a plurality of modes predetermined by the pattern of each unit signal obtained from an information source by referring to surrounding signals that have a correlation with it; this mode selection circuit Each encoding device encodes each sequence selected by the circuit in accordance with the code allocation format determined by the sequence, and the address of the untransmitted unit signal among the outputs of each encoding device is A communication device comprising a mode switching device that sequentially transmits data starting from the output of a coding device of a sequence to which the youngest unit signal belongs.