JPH03268576A - Band compressing/extending circuit for facsimile equipment - Google Patents

Abstract

PURPOSE:To improve the performance of the whole system by connecting a serial interface means between reading and recording parts and a line memory and reducing the load of an MPU for controlling the data transfer of image data. CONSTITUTION:Image data read out from the line memory 7 based upon the address A terminal of the memory 7 are transferred to a recording part 4 through the route of a data Q terminal and a data RQ terminal. On the other hand, the effective section of image data outputted from an one-line length control circuit 513 is transmitted to the recording part 4 through the route of a signal E terminal and a signal RE terminal. Thus, the image data are not directly outputted to a system bus 2 and only coded data are inputted/ outputted from/to the band compressing/extending circuit 5 to/from the system bus 2. Thereby, an MPU 1 directly controls the data transfer of only the coded data whose data volume is compressed from that of the image data, so that the load of the MPU 1 required for data transfer can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to Group 3 facsimile equipment (rG3F
In order to reduce the amount of data sent and received in MH (Modified AXJ), image data is
ed Hoffman), MR (Modified
Relative Edge Address Dif
ference), MMR (Modified
The present invention relates to a band compression/expansion circuit that compresses or expands using an encoding method such as MR).

[Conventional technology]

The configuration of a conventional 03 FAX is shown in FIG. In the same figure, 1 indicates each block described below as a system hash line 2.
Controlled through MPU (Micro Processor Unit)
, 3 uses an optical reading device such as a contact image sensor to read the white and black of the document, and for example, white is at rLJ level,
A reading section 4 converts black into an rHJ level digital electric signal, a recording section 4 outputs the image data received and restored by a band compression/expansion circuit 5 to be described later to a printer, etc., and 5 a recording section which outputs image data to reduce the amount of data. 6 is a memory that stores the data when each block processes the data; 7 stores the image data read by the reading section 3 line by line; A line memory stores the image data expanded by the compression/expansion circuit 5 line by line, and a modem 8 modulates the data to be transmitted in analog form and sends it out to the telephone line, and also digitally demodulates the data received from the telephone IL. , 9 is a direct memory access controller.

The band compression/expansion method performed by the band compression/expansion circuit 5 includes a one-dimensional encoding method such as MH method, MR
Two-dimensional encoding methods such as M'MR method and CCIT
Recommended by T (International Telegraph and Telephone Advisory Committee).

FIGS. 6 and 7 are explanatory diagrams showing how data flows through each block when transmitting and receiving data in G3 FAX. FIGS. 8 and 9 are flowcharts of a part of the program executed by the MPUI at the time of transmission and reception, respectively.

In FIGS. 6 and 7, 8 indicates image data,
↓ indicates encoded data.

Hereinafter, the time of transmission and the time of reception will be explained in order.

First, we will explain the time of transmission (see Figures 6 and 8).
. The reading unit 3 optically reads the original to be transmitted and converts it into white-rLJ and black-rHJ digital electrical signals (image data) depending on whether the original is white or black. The converted image data is stored in the line memory 7. A facsimile machine treats each line of a document as one unit.

The reading section 3 converts the original into image data of usually 8 bits per 1 mm. Therefore, image data of 1728 bits per line in A4 size and 2048 bits per line in B4 size is generated.

The transmission speed of current telephone lines is 9600 bits/second. If one line of image data is transmitted as it is over a telephone line, it will take 180 m5/line for A4 size data. Currently, this takes too much time, and faster processing is required. Therefore, methods are being used to increase the transmission speed by compressing the image data to reduce the amount of data. For example, G3FAX uses this method.

As for this compression method, as mentioned above, one-dimensional encoding methods such as the MH method, two-dimensional encoding methods such as the MR method, the MMR method, etc. are recommended as internationally unified methods by the CCTTT. By using these methods, the amount of data to be transmitted is reduced to about 1/10 or less. Therefore, the transfer speed improves as the amount of data decreases.

The band compression/expansion circuit 5 converts image data into encoded data using an encoding method. The amount of encoded data is reduced compared to the original image data and is stored in the memory 6.

The operation of the program when encoding data will be described below with reference to FIG. In step S1, data for one line is read from the line memory 7. In step S2, it is determined whether reading of one line of data is completed. If the answer is NO,
Control returns to step S1, and if the answer is YES, control proceeds to step S3.

In step S3, the read data for l lives is encoded. The encoded data is temporarily stored in memory 6 and sent to the telephone line by modem 8.

In step S4, it is determined whether to encode the next line. That is, it is determined whether to continue transmission. If the answer is YES, control returns to step S1, and if the answer is No, the program ends.

The modem 8 reads the encoded digital signal data from the memory 6 and converts it into an analog signal. The converted analog signal is sent to the telephone port [L and transmitted to the other party.

Next, the case of reception will be explained (see FIG. 7 and FIG. 9).

The analog signal transmitted through the telephone line is converted into coded digital signal data by the modem 8 and stored in the memory 6.

The band compression/expansion circuit 5 expands the encoded data compressed by the aforementioned encoding method and decodes it back to the original image data. The decoded image data is stored line by line in the line memory 7.

The decoded image data stored in the line memory 7 is
The data is output to a recording unit 4 such as a printer. The recording unit 4 records image data line by line on recording paper. By recording multiple lines while gradually feeding the recording paper, the original image is formed on the recording paper.

Referring to FIG. 9, the general operation of the MPUI program when decoding encoded data will be described. In step Sll, data for one line is read from the line memory 7.

In step 512, it is determined whether reading of one line of data has been completed. If the answer is NO, control returns to step Sll; if the answer is YES, control proceeds to step S13.

In step S13, one line of data is output to the recording section 4.

In step S14, it is determined whether or not to record and output the next line. If the answer is YES, control returns to step 311; if the answer is No, the program ends.

[Problem to be solved by the invention]

In the case of G3 FAX, a document is transmitted or received through the series of flows described above. At the time of transmission, the reading section 3
The data converted into image data using the optical reading device is temporarily stored in the line memory 7 via the system bus 2. Thereafter, the band compression/expansion circuit 5 reads the image data line by line from the line memory 7 via the system path 2, compresses it, and converts it into coded data.

Further, at the time of reception, the image data decoded from the encoded data by the band compression/expansion circuit 5 is temporarily stored in the line memory 7 via the system lot 2. Thereafter, it is output line by line to the printer in the recording section 4 via the system hub 2.

In this way, reading section 3Q line memory 7, line 7C=
==6 All image data exchange between the band compression/expansion circuit 5, line memory 7-5 and recording section 4 is done through system path 2.
This data transfer is normally controlled by the MPU.
I or a direct memory access controller (hereinafter referred to as rDMAcJ) 9 performs this.

This image data is 1728 bits/line in A4 size and 2048 bits/7 bits/line in B4 size, so the amount of data is enormous. When transferring data between memories (MPUI is 1106-), it can only be done in units of the number of bits of the MPUI data bus (16 bit units), so when transferring image data, Read and write operations must be repeated hundreds of times, and the MPUI takes most of its time controlling the image data transfer, leaving no room for other processing, making it difficult to improve the overall system performance. be. Furthermore, even if data transfer is performed by DMAC9, which is dedicated to controlling data transfer instead of MPUI, data transfer still takes about half the time compared to MPUI, and while data transfer is in progress, Since DMAC9 has the right to use system bus 2, MPUI cannot use system bus 2. Therefore, since MPU1 cannot access peripheral devices, the data transfer is completed and the right to use system bus 2 returns to MPUI. Even if you use this method, the performance of the entire system cannot be improved as much as expected because there is always a period of time when nothing is done.

Conventionally, as a means of increasing the usage efficiency of the MPUI, a method has been adopted in which the system path 2 and the image data bus 2a are separated, as shown in FIG.

In the configuration diagram shown in FIG. 10, the flow of data during transmission and reception is the same as in FIGS. 6 and 7. The difference from the system in Figure 5 is the reading section 3Q that exchanges image data.
The line memory 7, line memory 7O-=O band compression/expansion circuit 5, line memory 7) recording section 4 is separated from the system hash 2, and its control is entrusted to the sub-MPU10.

Therefore, the system has 2 controlled by the main MPUI.
Since there is only compressed encoded data with a smaller amount of data than the image data, there is no need to control the transfer of the image data, so the MPU
The load on I is extremely reduced, and by performing other processing in proportion to the reduced load, the performance of the system as a whole can be improved.

However, in the multi-bus system as shown in FIG.
10 is required separately, the system configuration becomes large-scale, and there is a problem that the manufacturing cost increases.

The present invention has been made in view of these points, and its purpose is to provide a band compression/expansion circuit for a facsimile machine that does not require a large-scale system configuration, has an inexpensive configuration, and improves MPU usage efficiency. It's about getting.

[Means to solve the problem]

In order to achieve such an object, the present invention provides a serial interface means between the reading section, the recording section, and the line memory.

[Effect]

In the band compression/expansion circuit for facsimile devices according to the present invention, since image data does not appear on the system bus, the load on the MPU for controlling the data transfer of image data can be extremely reduced, and the reduced load can be By imitating other processes, it is possible to improve the performance of the entire system.

〔Example〕

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 2 is a configuration diagram showing a G3 FAX using an embodiment of the band compression/expansion circuit according to the present invention, and FIG. 1 is a system diagram showing an embodiment of the band compression/expansion circuit according to the present invention.
This embodiment uses a serial bus as an interface between the band compression/expansion circuit 5, the reading section 3, the recording section 4, and the line memory 7. In FIG. 2, reference numeral 51 indicates an interface section as serial interface means, 52 a band compression/expansion section, 511 a selector, 512 an address counter, and 513 a 1-line length control circuit.

In FIG. 1, SD is the image data input from the reading section 3, SC is the image data transfer lock input from the reading section 3, SE is the signal input from the reading section 3 and defining the data transfer section, and RQ is the image data input from the reading section 3. Image data output to the recording unit 4, RC is the image data transfer lock input from the recording unit 4, RE is a signal output to the recording unit 4 and defining the data transfer section, and CD is input from the band compression/expansion unit 52. The image data to be processed, CC is the band compression/expansion unit 5
CQ is the image data output to the band compression/expansion section 52, CE is a signal that defines the data transfer section between the band compression/expansion section 52, and D.
is the image data output to the line memory 7, W is the write signal output to the line memory 7, Q is the image data input from the line memory 7, A is the address of the line memory 7, and C is the address of the line memory 7. The clock signal E of the address counter that generates is a signal that defines the length of one line of the line memory 7. Furthermore, WR, RD
, D, ~Dn are write signals, read signals, and data for exchanging data between the MPUs 1, and DB is a data bus. Furthermore, the selector 511
, the recording section 4, and the band compression/expansion section 52. This circuit connects to the line memory 7 and selects a signal for each operation.

In FIG. 1, an interface section 51 surrounded by a dotted line is an interface section between the reading section 3, recording section 4, line memory 7, and band compression/expansion section 52, which is newly added this time.

In the 03 FAX shown in FIG. 2, the data flow during transmission and reception is the same as in the conventional example, and can be shown in FIGS. 6, 7, 8, and 9.

In the 03 FAX shown in FIG. 2, when exchanging image data during transmission and reception shown in FIGS. 6 and 7, a data transfer control circuit is newly added to the band compression/expansion circuit 5, and the data bus is By providing it separately from the system bus, the need for the MPU 1 to control data transfer via the data bus is eliminated.

The band compression/expansion circuit shown in FIG. 1 uses a serial bus in which a data transfer control circuit can be easily constructed.

3 and 4 show the timing of reading and writing data to the line memory 7 of the serial bus shown in FIG. 1. 2 using Figures 1, 3, and 4.
The operation of the figure will be explained.

First, the transmission from the reading section 3 to the line memory 7 at the time of transmission will be explained (see FIG. 3).

One line of image data (1 line on A4) generated by the reading unit 3
728 bits, 2048 bits in B4) SD (Figure 3 (
C)) is serially input to the selector 511. At this time, a synchronous clock SC (FIG. 3(b)) for transferring the image data SD and a signal SE (FIG. 3(a)) defining one line of valid data section are input. Regarding these three signals, the selector 511 shown in FIG.
The terminal of the cup), the terminal of the clock SC, the terminal of the clock C (Fig. 3 (d)) and the terminal of the write signal W (Fig. 3 (f)) are connected, and D and W are input to the line memory 7, and the terminal of the clock SC is connected. is input to the address counter 512 and generates the address A of the line memory 7 (FIG. 3(e)). Image data is written into the line memory 7 by these signals.

Next, the transmission from the line memory 7 to the band compression/expansion circuit 5 during transmission will be explained (see FIG. 4). The band compression/expansion unit 52 outputs a synchronous clock CC (
The terminal of the selector 511 to which the signal (FIG. 4(b)) is input is connected to the terminal of the clock C (FIG. 4(d)), and the address counter 512 inputs the address A of the line memory 7 (FIG. 4(e)). Occur. With this address A, the line memory 7 performs a read operation, data Q - data CQ.
(The image data is transferred to the band compression/expansion unit 52 through the routes shown in FIG. The effective interval for one line of the image data to be processed is calculated by multiplying the signal E by the signal E (Figure 4 (a)).
The information is transmitted to the band compression/expansion section 52 via the route .

Next, from the band compression/expansion section 52 at the time of transmission, the memory 6
We will explain the transmission to. The image data read by transmission from the line memory 7 to the band compression/expansion circuit 5 is
The data is compressed according to the encoding method such as the MH, MR or MMR method described above and converted into encoded data. This converted encoded data is read from the band compression/expansion unit 52 via the system bus 2 by the MPUI, and further written to the memory 6.

Next, the transmission from the memory 6 to the modem 8 at the time of transmission will be explained. The MPUI transfers the encoded data from the memory 6 to the modem 8 via the system bus 2, puts the data on the telephone line L, and ends the transmission.

Next, the transmission from the modem 8 to the memory 6 at the time of reception will be explained. The MPUI stores the encoded data sent from the telephone line from the modem 8 to the memory 6 via the system bus 2.

Next, from the memory 6 at the time of reception, the band compression/expansion unit 52
We will explain the transmission to. MPUI is system bus 2
The encoded data is transferred from the memory 6 to the band compression/expansion unit 5 via
Transfer to 2.

Next, the transmission from the band compression/expansion unit 52 to the line memory 7 at the time of reception will be explained (see FIG. 3). The encoded data read in by transmission from the memory 6 to the band compression/expansion section 52 is expanded according to an encoding method such as MH, MR or MMR method, and converted into original image data. This converted image data is sent to the line memory 7 via the route data CD-data D (FIG. 3(c), fg)). Furthermore, the clock C for data transfer
Address A (Fig. 3 (e)) by C (Fig. 3 (b))
, a write signal W (FIG. 3(f)) is generated, and the image data is written to the line memory.

Next, the transmission from the line memory 7 to the recording unit 4 at the time of reception will be explained (see FIG. 4).

The terminal of the synchronized clock RC (FIG. 4(b)) and the clock C (FIG. 4(d)) for data transfer from the recording unit 4 are connected, and the address A of the line memory 7 (FIG. 4(e)
)) occurs. The image data read from the line memory 7 by this address is data Q - data RQ.
(The image data is transferred to the recording unit 4 through the routes (cl, (fl) in FIG. The information is transmitted to the recording section 4 via the route shown in Figure (a).

As described above, image data is not directly output to the system bus 2, and only encoded data is input to and output from the band compression/expansion circuit 5 to the system bus 2.

Data transfer of image data between reading section 3 → line memory 7, line memory 7 ← - band compression/expansion section 52, line memory 7 and recording section 4 is in serial format, so basically it is used for data transfer. This is possible if there is a clock, and the control circuit can be realized with a simple configuration.

Therefore, it is only necessary for MPUI to directly control data transfer for encoded data whose data amount is more compressed than image data;
Since the load on the system can be reduced and other processing can be performed by the reduced load, the performance of the system as a whole can be improved.

〔Effect of the invention〕

As explained above, the present invention provides the serial interface means between the reading section, the recording section, and the line memory, so that the image data does not appear on the system bus, and the MPU is able to transfer the image data. Since the control load can be extremely reduced, the reduced load can be applied to other processes, thereby improving the performance of the entire system.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the band compression/expansion circuit according to the present invention, FIG. 2 is a block diagram showing a G3 FAX using an embodiment of the band compression/expansion circuit according to the invention, and FIGS. The figure is a time chart for explaining the operation of the system in Figure 1 during transmission and reception, and Figures 5 and 10 are for the conventional 0
FIG. 6 and FIG. 7 are explanatory diagrams showing the flow of data in the facsimile machine, and FIGS. 8 and 9 are flowcharts for explaining the operation of the facsimile machine. DESCRIPTION OF SYMBOLS 1... MPU, 2... System hash, 3... Reading part, 4... Recording part, 5... Bandwidth compression/expansion circuit, 6...
...Memory, 7...Line memory, 8...Modem,
L...Telephone line.

Claims (1)

[Claims] A facsimile device comprising a band compression/expansion circuit for transmitting/receiving a reduced amount of data by compressing or expanding image data, and comprising a serial interface means between a reading section, a recording section, and a line memory. band compression/expansion circuit.