JPS6342467B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning control method for high speed facsimile transmission.

In high-speed facsimile, there is a well-known scanning method that changes the scanning line density between parts of the document to be transmitted, where the information is coarse and does not require high resolution, and parts where the information is dense and requires high resolution. A method is also known that further develops this and makes the resolution in the scanning line direction variable.

In the conventional method, the density of information in a certain scanning line (this is referred to as the Nth scanning line) is checked and the next (N+1)th scanning line is set to either 8 lines/mm or 4 lines/mm. so that the scanning line density is
Controls the pitch of sub-scanning. Also, N, N+
Check the density of information in the three scanning lines 1 and N+2, and if it is coarse, skip N+1 and change the information to N and N.
+2 two scanning lines, and if dense, N and N+1
N+2, in which the information of the two scanning lines is transmitted after that, is also known.

However, these conventional sub-scanning control methods have the following problems. As shown in FIG. 1, the first problem is how to send information regarding this scanning interval to the receiving side. Second
When encoding the Nth scanning line,
Since the photoelectric conversion result of the N+1 scanning line has already been read and encoded, and the density of the information is detected from the encoded signal, it is difficult to change the scanning line density (pitch).

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems in controlling the sub-scanning of a facsimile apparatus, to appropriately control the scanning line density of the sub-scanning according to image information by a simple means, Accordingly, it is an object of the present invention to realize a method for efficiently transmitting sub-scanning information, that is, information regarding scanning intervals to a receiving side.

The present invention relates to a facsimile device that encodes and transmits information obtained by scanning an image. Where the number of bits is less than a certain number, scanning line control is performed, and sub-scanning control information is extracted from the received image data to control the sub-scanning spacing of the receiver. .

Here, image data refers to the number of bits of the encoded signal,
Defined as the number of bits when decoding an encoded signal.

According to the present invention, sub-scanning control on the transmitting side and the receiving side can be matched without the need to create a special code using code signals prepared in conventional facsimile machines.

FIG. 2 shows the configuration of a transmitting section in a conventional sub-scanning control system, and its operation is as follows. That is, information read from the original 1 by the Nth scanning line and photoelectrically converted by the detector 2 passes through the changeover switch 3 located at the solid line position shown in the figure, and is stored in the line memory 4. When the scanning of the Nth scanning line is completed, the changeover switches 3 and 5 are switched to the dotted line positions, and the information stored in the line memory 4 is sent from the switch 5 to the encoder 6 and encoded. At the same time, information read out by the N+1 scanning line and photoelectrically converted by the detector 2 is stored in the line memory 7 through the changeover switch 3. Note that the information stored in the line memory is a binary image signal of one scanning line, which is the same as the number of pixels of one line, which is a specified number of bits. As is generally well known, the encoded signal is a code that compresses the redundancy of information, such as a run-length code or a modified Huffman (MH) code, and generally the number of bits is reduced where there are many changes in the image. will increase.

The information bit signal 8 of the Nth scanning line encoded by the encoder 6 is applied to a bit counting circuit 9, where the number of bits is counted. When the scanning of the Nth scanning line is completed, a scanning line end signal 10 is applied to the bit counting circuit 9. At this time, if the number of encoded bits per scanning line is less than the specified value, the bit counting circuit 9 is In response to a command, useless information, that is, a dummy signal (Fill code) 12 is sent out from the dummy signal generation circuit 11;
It is applied to the OR circuit 14 together with the encoded information signal 13 from the encoder 6, where they are combined and sent out. In this case, the data is normally sent to the modem 16 via a FIFO (first-in, first-out) memory 15. Note that the bit counting circuit 9 receives the scanning line end signal 10.
When this is applied, the output 17 is sent out, and the pulse motor 18 is driven to move the document 1 by one scanning line (sub-scanning is performed).

In the embodiment of the present invention, this dummy signal 1
When it is necessary to add 2, that is, when the number of bits of the encoded signal is small, it is assumed that the image information of the original is coarse and the scanning line density should also be coarse.
More pulse signals than usual are sent to the pulse motor 18 for moving the original 1, and the scanning line density of the N+2th scanning line to be photoelectrically converted thereafter is made coarser. FIG. 3 shows an embodiment of the present invention in which scan line density is controlled by such means.

A feature of this case is that an OR circuit 19 is newly provided, and the output of this OR circuit 19 is applied to the pulse motor 18 to move the document. That is, the total number of bits of the encoded signal of one scanning line (Nth scanning line) is determined in the counting circuit 20 using the signal 8 indicating the sign bit of the information of one scanning line (in this case, the Nth scanning line), and this number is calculated. When the count value is less than a predetermined value, the signal 21 is sent out to operate the dummy signal generation circuit 11, and the dummy signal 12 is sent out and added to the OR circuit 14 together with the encoded information signal 13 output from the encoder 6. .

On the other hand, in the conventional case, the pulse motor 1
However, in the present invention, if the count value of the sign bits in one scanning line in the counting circuit 20 is less than a predetermined value, the output 21 of the counting circuit 20 drives the dummy signal generating circuit 11 as described above. is operated, and the output 21 is applied to the OR circuit 19, and the pulse motor 18 is driven by the signal 22 combined with the scanning line end signal 10 from the encoder 6.
The scanning line density is reduced by increasing the amount of movement of the original 1. In this way, the scanning line density can be controlled in accordance with the number of encoded bits per scanning line, that is, the density of information on the document.

In the receiving section, the operation opposite to that of the transmitting section is performed. This is easily inferred, so I will only explain the gist as follows. That is, if a dummy code as described above is detected in the signal related to the Nth scanning line sent from the transmitter, in other words, if the number of encoded bits is less than a predetermined value, when recording the N+2nd scanning line, In addition, as in the case of the transmitter, the amount of drive of the recording paper movement monitor may be made larger than usual. That is, the scanning line density is made coarser. However, in this case, the recording surface becomes rough, so the same information is usually recorded twice. That is, a means is used for recording the information of the previous scanning line again as is.

Note that the transmission method of information regarding the scanning line pitch to the receiver, that is, the N+2th
In addition to detecting the dummy code, the following means can be used to indicate that the scanning density of the scanning lines is coarse and that the N+1th scanning line should be recorded coarsely (that is, twice in some cases). It is also possible to apply

(1) Determine whether the number of code bits per scanning line is greater or less than the specified value. This method of determining based on the number of bits is particularly effective in two-dimensional successive approximation coding.

(2) Also, as has been proposed in the past, a generally known coarseness/fineness determination circuit is provided in the receiving decoder, separate from the encoder, to perform the determination.

(3) A method of tentatively sending one scanning line information (dummy information) after the N+1 scanning line may be applied. However, in this case, only the synchronization signal (EOL) and some codes if necessary (ie, if the number of bits is insufficient to ensure the minimum time) are sent by the virtual scan line. In this way, when the information between the synchronization signals is decoded,
Since it does not reach the specified number of bits (for example, 1728 for A4 size), it is determined that an error occurred during transmission, and a normal receiver automatically records the N+1th scanning line instead of this virtual scanning line. Also, the scanning line density is automatically switched in the receiving section according to the transmitting section.

In addition to providing a dedicated device to perform each of the above-mentioned processing operations, it is also possible to implement them using a general-purpose processing device.

As mentioned above, as shown in the three methods in the embodiment and "Revisiting", the feature of the present invention is to extract information regarding the scanning line pitch from the received image data.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the temporal relationship between reading, encoding, and transmitting information in the N-th scanning line and the N+1-th scanning line, Fig. 2 is a block diagram showing this type of conventional device, and Fig. 3 is an illustration of the present invention. FIG. 1 is a configuration diagram showing an embodiment of the invention. 8... Information bit signal, 10... Scanning line end signal,
DESCRIPTION OF SYMBOLS 11... Dummy signal generation circuit, 18... Pulse motor, 19... OR circuit, 20... Counting circuit.

Claims (1)

[Claims] 1. In a facsimile device that encodes and transmits information obtained by scanning an image using a run-length code or a modified Huffman code, sub-scanning on the transmitter side is performed using a method in which the number of bits of the encoded signal is constant. Where the number of bits is greater than the number of bits, the scanning line spacing is controlled closely, and where the number of bits is less than the certain number, the scanning line spacing is coarsely controlled.
A scanning control method characterized in that sub-scanning control information is extracted from image data received on the receiver side to control the density of sub-scanning of the receiver. 2 In the scanning control method described in item 1, the sub-scanning control information is the number of bits of a decoded signal obtained by decoding a code signal between two synchronization signals (EOL) representing the end of a scanning line, and A scanning control method characterized by coarsening the receiver's sub-scanning when the number of signal bits does not reach a fixed number. 3 In the scanning method described in paragraph 1, the sub-scanning control information is the number of bits of the encoded signal for one scanning line, and where the number of bits of the encoded signal is greater than the certain number, the sub-scanning control information of the receiver is A scanning control method that closely controls the sub-scanning of the receiver when the number of bits of the encoded signal is less than the predetermined number.