JPH0831950B2 - Facsimile transmitter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a facsimile transmitter for converting an original image into an electric signal and transmitting the electrical signal, and more particularly to a facsimile transmitter using a storage type optical line sensor.

<Prior Art> In a facsimile machine, a document is intermittently moved in order to reduce the memory capacity and to match the transmission with the other device, and charges are asynchronously stored in an optical sensor for reading the document. . However, with such a configuration, the reading range by the optical sensor or the reading interval is not constant and the resolution deteriorates.

Therefore, in the prior art, as shown in FIG. 1, there is a method in which there is a periodic relationship between the movement of the original and the reading from the optical sensor so that the data accumulated in the sensor by the light is not read while the original is moving. Alternatively, a method has been adopted in which the ratio of the moving time of the document in the storage time of the optical sensor is reduced.

In FIG. 1, time T ₁ is the moving time of the document and T ₂ is the storage time of the optical sensor.

By the way, in the case of performing high-speed reading by such a method, it is necessary to shorten the document moving time T ₁ or the photosensor storage time T ₂ . In order to reduce the moving time T _{1 of the} document, an expensive stepping motor with a large torque is required, which increases the weight of the device and increases the noise.

Further, in order to shorten the accumulation time T ₂ of the optical sensor, it is sufficient to increase the amount of light received by the optical sensor, but for that purpose, a light source with high brightness is required, which results in a high cost including power consumption.

<Purpose> In view of the above-mentioned problems, the present invention, when reading a document image, makes a relative movement between the document and the line sensor, transfers image data accumulated in the line sensor to a buffer, and stores an image stored in the buffer. An object of the present invention is to provide a facsimile transmission device capable of efficiently encoding data, and more specifically, a means for generating a pulse at a constant cycle, and a document and a line sensor which are arranged in one cycle for one cycle of the pulse. Moving means for performing relative movement of lines at a constant speed, a line sensor for repeatedly executing the accumulation of image data for one line in response to the pulse, and a plurality of lines of image data accumulated by the line sensor for three or more lines. A buffer for storing lines, a transfer unit for transferring the image data accumulated in the line sensor to the buffer, and a storage in the buffer Program control for encoding the generated image data by a main routine process according to a main program, and controlling the operation of the moving means and the transfer means by an interrupt process according to an interrupt program activated in response to the generation of the pulse. In the interrupt processing, when the pulse is generated,
If the image data that has not been encoded is not stored and there is a buffer for one line that is not in a state in which the data accumulated in the line sensor is transferred, When the moving means is caused to perform the relative movement of the constant speed for one line, and the relative movement of the constant speed for the one line is performed by the moving means in one cycle immediately before the generation of the pulse, It is an object of the present invention to provide a facsimile transmission device characterized by causing the transfer means to execute transfer of image data of one line accumulated in the line sensor.

<Examples> Hereinafter, the present invention will be described in detail based on Examples shown in the drawings.

FIG. 2 illustrates one embodiment of the present invention. In the figure, reference numeral 1 is a main control unit (CPU), which controls each part of the apparatus.

Reference numeral 2 denotes a motor control unit that controls the rotation of the motor 4 that moves the document 10 based on a command from the CPU 1.

Reference numeral 3 denotes a reading unit having an optical line sensor for accumulating the reflected light from the original 10, and the reflected light from the original illuminated by the light source 9 is condensed by the lens 11 to read the original.

The reading unit 3 is connected to the calculation unit 7 via buffers 5 and 6 having a capacity to store the data of one line of the read document, and the calculation unit 7 is connected to the memory 8.

The data in the buffer 5 and 6 to the operation unit 7 by Recommendation T ₃ of CCITT (International Telegraph and Telephone Consultative Committee) performs redundancy reduction processing by the one-dimensional encoding or two dimensional coding like. The processed read data is stored in the memory 8.

When no data is stored in the buffers 5 and 6 based on the above circuit configuration, the CPU 1 requests the motor control unit 2 to start moving one line of the original 10 for reading one line for reading one line. Issue signal a.

At the same time, the CPU 1 erases the accumulated data up to now to the reading unit 3 and outputs an accumulation start signal b for starting a new accumulation.

Upon receiving the signal a, the motor control unit gradually moves the document for one line within the accumulation time T ₃ required by the optical sensor in the reading unit 3.

When T ₃ has elapsed since the reading unit 3 started to store the reflected light, the CPU 1 issues a transfer request signal c to the reading unit 3 to transfer the read data to the buffers 5 and 6.

When the transfer to the buffer 5 is completed, the calculation unit 7 performs the redundancy suppression processing of the data in the buffer and stores it in the memory 8.

The buffers 5 and 6 are alternately used by the reading unit 3 and the computing unit 7.

When the stored read data is started to be transferred to the buffer 5 or buffer 6, if the data in the other buffer has already been processed by the arithmetic unit 7, the next line is transferred at the same time as the transfer of the read data to the buffer. Reading, that is, the movement of the original 10 and the accumulation of the original image on the optical sensor of the reading unit 3 are started. Also, when transferring to one of the buffers 5 and 6,
If the data in the other buffer is being processed by the arithmetic unit 7, the original 10 is not moved.

And the period during which the manuscript 10 has not moved (for example, period T ₃ )
The information stored in the optical sensor at 1 is not transferred to buffers 5 and 6.

Therefore, only the information stored in the optical sensor is transferred to the buffers 5 and 6 during the period when the document 10 moves.

FIG. 3 shows the amount of document displacement and the timing chart of each signal.

In FIG. 3, buffers A and B indicate buffers 5 and 6, respectively, and hatched portions indicate that valid data exists in the buffers.

The actual operation will be described below with reference to the timing chart of FIG.

First, at the time of P ₀ , since there is no valid data in the buffer 5, the movement of one line of the document is started.

On the other hand, at the point of P ₁ , the transfer of the data accumulated in the period of time t ₁ to the buffer 5 is started. This state is shown by the shaded portion l ₁ .

Further, since there is no valid data in the buffer 6 at this time, the movement of one line of the document is simultaneously started.

Furthermore, at the time of P ₂ , transfer of the data accumulated during the period of time t ₂ to the buffer 6 is started. This state is indicated by the diagonal line l ₂ .

However, at this time, since the data in the buffer 5 has not been completely processed by the arithmetic unit 7, the document is not moved.

On the other hand, the stored data of the optical sensor of this period is not used a period of time t ₃ at the time of P _3, since the movement of the original is not performed.

At this time, since there is no valid data in the buffer 5, the movement of one line of the document is started.

 The same operation is repeated thereafter to read the original.

As described above, the accumulation start signal b of the optical sensor shown in FIG. 3 is a reference signal for moving the document, the accumulation start of the optical sensor, and the transfer of the image signal to the buffer, that is, a system clock. And the cycle of this system clock t ₁ , t ₂ , t ₃ , t ₄
(All equal) is set to the minimum transmission time of one line of image data defined in the CCITT T30 standard.

Here, the above-mentioned minimum transmission time defines the minimum time required for the facsimile apparatus to perform encoding processing, move one line of the document, or move one line of recording paper. ing. In this embodiment, the system clock cycles t _{1 to} t ₄ are made to coincide with the minimum transmission time. Therefore, even though the encoding has already been completed, the accumulation of one line of the optical sensor has not been completed, or the accumulation of one line of the optical sensor has been completed even though the movement of the document has been completed. It doesn't mean you haven't. That is, the dead time is eliminated and the original can be efficiently read.

In the above example, the time required to feed the original by one line is equal to the accumulation time of the optical sensor.
Even if the difference is about 30%, the same effect can be obtained.

As described above, in the first embodiment, an example in which two buffers each containing one line of data are used has been described. However, a second embodiment in which the buffers for three lines are used to control by the microprocessor will be described below. To do. The second embodiment is a facsimile machine and its control block diagram is shown in FIG.

In the figure, 11 is a main CPU that performs encoding processing and reading control, 12 is a read-only memory (ROM) that stores the control program of the main CPU 11, 13 is a buffer memory that temporarily stores image data for 3 lines, and FiFo (Fast in Fast
out) memory and random access memory (RAM) for temporarily storing flags and the like necessary for controlling the CPU 11, 14 is a direct memory access (DMA) controller (DMAC),
15 is a sub CPU that controls the driver circuit 16 that drives the document feeding motor 17 that sends the document, 19 is a timer circuit that generates a pulse signal at a minimum transmission time of 10 msec, and 20 is a CCD for reading that reflects light from the document. It is divided into an exposure unit 21 for accumulating corresponding charges and a transfer unit 22 for transferring to the outside.

23 is an amplifier that amplifies the output of the CCD 20, 24 is a binarization circuit that binarizes the output of the amplifier 23 into black and white binary, and 25 is the output serial signal of the binarization circuit 24. A bit-to-serial (parallel-to-signal converter) 26 is a modem that modulates a transmitted signal and a received signal is demodulated. The output of the modem 26 is transmitted to another facsimile device through a telephone line.

The output pulse of the 10 mS timer circuit 19 is input to the interrupt terminal of the main CPU 11 and the CCD 20 at the same time. CPU11
Performs an interrupt process described later according to an interrupt input. CCD20
Transfers the electric charge accumulated in the exposure unit 21 to the transfer unit 22 by the output pulse of the timer circuit 19, and the exposure unit 21 starts the accumulation simultaneously with the transfer.

FIG. 5 shows the processing share of the main CPU 11. Main CPU 11
By the interrupt processing of (1), the operation of transferring the image signal read by the reading system 30 including the CCD to the buffers 32 to 34 and the operation of the drive system 31 for driving the document conveying motor 17 are controlled.

Further, the CPU 11 performs the encoding process (35) on the image data of the buffers 32 to 34 by the main routine and transfers the image data to the FiFo memory 36.

Here, the document conveyance motor 17 is driven at a low speed, and during reading, one line is always conveyed with a minimum transmission time of 10 mS.

Also, the storage time of the CCD 20 is designed to be 10 mS, and in order to make the read line density uniform, only the data stored in the CCD 20 during 10 mS during driving the motor is used.

To further explain the CCD, the accumulation operation is 10 mS
Each is unconditionally performed. On the other hand, the motor drive is judged by software, and one line drive (10 mS) is intermittently performed. The operations of both units in units of 10 mS are synchronized by the output pulse of the timer circuit 19.

Since the motor and CCD are controlled periodically, the software generates an interrupt every 10 mS. The reading of one line (up to the storage in the line buffer) is completed by three times of this interrupt.

(First interrupt) If the storage destination line buffer is empty, the motor starts driving one line.

(Second interrupt) The data stored in the exposure unit 21 of the CCD 20 is latched in the transfer unit 22, and the DMA operation is activated.

(Third interrupt) Set a flag to notify the main routine that the data in the line buffer is valid.

Before explaining the present embodiment, FIG. 6 shows the operation in the case of one line buffer.

With the 10 mS pulse n, the line buffer is "empty", so the sub CPU 15 for motor control is instructed to start driving the motor for one line.

At the 10 mS pulse n + 1, the DMAC 14 is set to start transferring the CCD data to the line buffer. this
DMA is always completed within 10mS.

With 10mS pulse n + 2, DMA started at the previous n + 1
Since the above has been completed, the main routine of the encoding process is notified that the line buffer is Full.

At 10 mS pulse n + 3, the line buffer has already become "empty", and therefore the same processing as 10 mS pulse n is performed again.

In this way, reading of one line is completed, but if this line buffer is one, reading of one line requires at least 30 mS.

By the way, if 10 mS or more is required for the encoding process, it takes 40 ms or more to read one line.

That is, if only one line buffer is used, 1
The reading speed of the line 30mS is the limit. This is one line
In this embodiment, the number of line buffers is three in order to obtain 10 mS. This operation is shown in FIG. FIG. 7 is a table of processing contents for each buffer performed in each interrupt and a data flow.

“0” in the processing content of the interrupt means that the target buffer is not “empty”, and nothing is done at this time.

As shown in FIG. 7, the above-mentioned three operations are performed in parallel for each line buffer. Therefore, if the encoding process is performed within the minimum transmission time of 10 mS,
The manuscript can be moved at all times and no waiting time is required.

FIG. 8 shows the control flow of the main routine for the encoding processing of the main CPU 11 of FIG. 4, and FIG. 9 shows the control flow of the interrupt processing routine of the CPU 11. The processing programs shown in FIGS. 8 and 9 are stored in the ROM 12 shown in FIG.

As described above, since the CCD is accumulated, the original is moved by one line, and the original is transferred to the buffer within the minimum transmission time, it is possible to read the original very efficiently.

In the present embodiment, the CCD transmission time T _S and the moving time T _M for one line of the original are matched as the minimum transmission time T _Min , but it is _sufficient if T _Min ≧ T _S , T _M. Of course the time required for DMA
T _D is preferably T _Min ≧ T _D.

By using three line buffers like this,
When the encoding process is completed within the minimum transmission time, the document can be read without stopping the document. Further, since the image data read while the document is moving is stored in the buffer memory, the document can be read at a uniform density. Furthermore, since the time required to move one line of the original is almost equal to the storage time of the optical sensor and only the data accumulated when the original is moved is read out, the original can be moved at a low speed and a small and inexpensive motor can be used. It will be possible.

Moreover, since the accumulation time of the optical sensor can be lengthened to some extent, the power of the light source can be reduced and a small light source can be used. Therefore, downsizing and labor saving of the device can be realized.

<Effect> As described above, according to the present invention, when reading a document image, the image data of the line sensor is accumulated according to the pulse generated at a constant cycle. Then, in response to the generation of the pulse, start the software interrupt program,
There is a buffer for one line that does not store image data that has not been encoded when the pulse is generated, and is not in a state in which the data accumulated in the line sensor is transferred. In this case, the moving means is caused to perform the relative movement at a constant speed for the one line, and the moving means performs one movement in one cycle immediately before the generation of the pulse.
When the relative movement at the constant speed for the line is executed, the transfer means is caused to transfer the image data of one line accumulated in the line sensor. Then, the image data accumulated in the buffer is encoded by the main routine processing according to the main program.

According to the present invention as described above, the main routine by the main program can be dedicated to the encoding process of the image data, and the relative movement between the document and the line sensor and the line sensor which need to be processed in synchronization with the accumulation operation of the line sensor. Since the transfer of the image data stored in the buffer to the buffer is controlled by the interrupt processing of the interrupt program that starts when a pulse with a fixed cycle is generated, the relative movement between the document and the line sensor and the image data stored in the line sensor are controlled. Efficient reading operation with simple control that interrupt processing is performed when the pulse is generated, without performing complicated control that executes image data encoding processing while checking the progress of transfer processing to the buffer It can be performed.

Further, according to the present invention, the original is read while the original and the line sensor are moving relative to each other by one line, and the accumulation operation of the line sensor and the relative speed of the original and the line sensor are adjusted in response to a pulse generated at a constant cycle. Since the movement and transfer of the image data accumulated in the line sensor to the buffer are performed, the reading operation during the relative movement of each line can be continuously repeated at a constant cycle, and the smooth operation with continuity can be performed. Image data can be read. As a result, the present invention can read image data that is not distorted as compared with image data that is read by a discontinuous reading operation that does not repeat the reading operation during relative movement line by line in a fixed cycle. You can

Further, normally, in order to read and encode image data of one line on a document, a moving period (one cycle is required) in which the document and the line sensor are relatively moved by one line, one line of image data is read from the line sensor. Three processing periods are required: a transfer period for transferring to the buffer (one cycle is required) and an encoding period for encoding one line of image data stored in the buffer (one cycle or more may be required). Therefore, in the case where the relative movement of the original and the line sensor is started after confirming that the buffer is empty for at least one line, the buffer of one line has three cycles from the start of the relative movement to the end of the encoding. It will be occupied over the above. Therefore, by setting the storage capacity of the buffer to 3 lines or more as in the present application, the image data of 3 lines at consecutive positions on the original are read by using different buffers and the above-mentioned 3 processing periods of each line are used. , The three processing periods can be simultaneously processed in parallel, so that it can be considered that one line of the document is apparently executed in one cycle. It is possible to perform an efficient reading operation in which the waiting operation for waiting for the buffer to become empty can be performed for the reading operation having continuity according to the pulse of the constant cycle described above as much as possible.

[Brief description of drawings]

FIG. 1 is a timing chart showing the relationship between movement of a document and accumulation / readout of an optical sensor for explaining a conventional method, FIG. 2 is a block diagram for explaining one embodiment of the present invention, and FIG. 3 is for this embodiment. FIG. 4 is a timing chart showing the relationship between document movement and accumulation / readout of the optical sensor, FIG. 4 is a control block diagram of the facsimile machine according to the second embodiment of the present invention, and FIG. 5 is a processing share of the main CPU of FIG. Fig. 6 shows the time chart when one line buffer is used, Fig. 7
The figure is a time chart for explaining the operation of the second embodiment.
FIG. 8 shows a control flow chart for the code processing of the main CPU of FIG. 4, and FIG. 9 shows a control flow chart of the interrupt processing routine.

Claims (1)

[Claims] 1. A means for generating a pulse at a constant cycle, a moving means for performing relative movement of the original and the line sensor for one line at a constant speed over one cycle of the pulse, and 1 according to the pulse. A line sensor that repeatedly executes the accumulation of image data for a line, a buffer that stores the image data accumulated by the line sensor for a plurality of lines of three lines, and the image data accumulated in the line sensor to the buffer Transfer means for encoding the image data stored in the buffer by a main routine process according to a main program, and
Program control means for controlling the operation of the moving means and the transfer means by interrupt processing according to an interrupt program activated in response to the generation of the pulse, and in the interrupt processing, when the pulse occurs, the code If there is a buffer for one line that does not store image data that has not been converted and that is not in a state allocated to transfer the data accumulated in the line sensor, move the line. In the case where the means performs the relative movement of the constant speed for one line and the relative movement of the constant speed for the one line is performed by the moving means in one cycle immediately before the generation of the pulse, the transfer is performed. A facsimile transmitting apparatus, characterized in that it causes the means to transfer the image data of one line accumulated in the line sensor.