JPH0832783A - Image reader - Google Patents

Abstract

PURPOSE:To reduce deterioration in the picture quality of a read image which is caused when an IFIO is always full of encoded data. CONSTITUTION:While image data by main scanning lines which are read by a scanner 1 are inputted to plural line buffers 2a in order, the image data inputted to the line buffer are taken out and processed by a sequential processor 3 in the input order and the processed image data are transferred to a next- stage processor through the FIFO memory 2b in order. This image reader is equipped with a 1-line control means 8 which performs control so that image data are transferred to the processor from the scanner by using one of the line buffers when the amount of untransferred data in the FIFO memory exceeds a specific upper-limit amount. Consequently, deterioration in the picture quality of the read image is reducible without increasing the cost of the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention sequentially inputs image data for each main scanning line read by a scanner into a plurality of line buffers, and the image data input to the line buffers in the order of input. The present invention relates to an image reading device that sequentially takes out the image data to a processing device, processes the image data, and sequentially transfers the processed image data to a next-stage processing device via a FIFO memory.

[0002]

2. Description of the Related Art Generally, a facsimile machine is shown in FIG.
It is configured as shown in FIG. In FIG. 1, a scanner 1 reads a document image, a photoelectric conversion element such as a CCD that reads an image for each main scanning line, a drive device that moves the document with respect to the photoelectric conversion element in a predetermined sub-scanning cycle, The photoelectric conversion element includes an image processing unit that converts the image read by the photoelectric conversion element into image data.

The RAM 2 sequentially transfers a plurality of line buffers into which image data for each main scanning line read by the scanner 1 is sequentially input and image data processed by a DCR 3 described later to a modem 4 described later. And a FIFO memory for temporarily storing the data until it is stored in a predetermined area with a predetermined capacity.
The control data of PU8 etc. are stored.

The DCR3, which is a processing device, compresses the image data input to the line buffer by a predetermined encoding method, and decodes the received image data to restore the original image information. . The modem 4 uses the F
The image data and various procedure signals stored in the IFO are modulated, while the received modulated image data and various procedure signals are demodulated. The NCU 5 is connected to a line, transmits / receives a modulated signal, and performs a predetermined line control. The plotter 6 records and outputs an image. The operation panel 7 receives various operations of a person who uses the facsimile device and displays information such as an operating state of the device.

The CPU 8 controls each of the above parts via the system bus 10 in accordance with a control program written in the ROM 9 and manages the exchange of data between the above respective parts.

When a document is transmitted by the facsimile apparatus configured as described above, the document to be transmitted is set on the scanner 1. Then, when a transmission operation is performed by the operation panel 7, the facsimile device calls the other party and transmits the document image according to a predetermined transmission control procedure. During this image transmission, the scanner 1 reads the image data for each main scanning line in the sub-scanning cycle while feeding the document in the constant sub-scanning cycle. The read image data for one line is sequentially transferred and input to one of the plurality of line buffers in the sub-scanning cycle.

Further, in parallel with the operation, the image data stored in the line buffer is sequentially taken out in the order of input, and the data is compressed and encoded by the DCR3. The encoded data is sequentially transferred to the FIFO and input.

In parallel with the operation, the data stored in the FIFO are taken out in the order of input, modulated by the modem 4, and transmitted via the NCU 5. In this case, the modulated data will be transmitted at the predetermined data transmission rate set by the predetermined transmission control procedure.

As described above, the facsimile apparatus simultaneously transmits the image of the original while reading it. However, when all of the plurality of line buffers are filled with the image data, the scanner 1 does not drop the image data of the original, so that scanning,
Image reading and image data transfer are stopped. The plurality of line buffers alleviate the influence on the operation of the scanner 1 of the change in the time required for the encoding process of the image data of one line of the DCR3 due to the information amount of the image data being different for each line. The DCR
If the encoding process of 3 is delayed, the image data will eventually fill up.

The DCR 3 continues to operate until the FIFO is filled with encoded data as long as there is image data to be processed in the plurality of line buffers.
When the IFO is full, the operation is stopped because the encoded data is not lost.

The amount of coded data stored in the FIFO is the modem 4 at a speed corresponding to the predetermined data transmission speed.
However, the amount of the new encoded data transferred from the DCR3 increases.
If the rate at which the encoded data decreases is faster than the rate at which the encoded data increases, the FIFO will not be filled with the encoded data. However, if the rate of decrease is slower than the rate of increase,
That is, when the predetermined data transmission speed is slower than the image reading speed which is taken as the amount of encoded data generated by the DCR3 per unit time, the FIFO eventually becomes full of encoded data.

In other words, due to the relative slowness of the data transmission rate, the FIFO is first filled with encoded data,
The operation of DCR3 is stopped. Then, the line buffers of the plurality of lines are filled with image data. Then, the operation of the scanner 1 is finally stopped.

The operation that occurs when the data transmission speed is much slower than the image reading speed will now be described.

Even when the operation of the scanner 1 is stopped,
Since the encoded data is processed at the predetermined communication speed, the FIFO has a space for transferring new encoded data from the DCR3, and the DCR3 performs the encoding process of the image data stored in the line buffer. Restart, FIF
Transfer the new encoded data to O. And again FIF
O is full. By repeating such an operation, the encoding process of all the image data in one line buffer which is being processed is completed at some point. That is, one of the plurality of line buffers that has been full is free.

Further, since the scanner 1 performs sub-scanning in synchronization with a constant timing which is continuous in the same cycle as the predetermined sub-scanning cycle, it also synchronizes with the timing when starting sub-scanning from the stopped state. Therefore, during the shortest time from the stop to the restart of the sub-scanning, that is, during the predetermined sub-scanning cycle, the image data of two or more line buffers is generated depending on the amount of information of the image data for each line. It may be processed and two new line buffers may be vacated.

The scanner 1, which operates as long as there is an empty line buffer, reads the image by sub-scanning only once if one line buffer is empty at the above timing, and the image data is free. Input to one line buffer. At the next timing, since the image data has been input to the line buffer that is currently vacant, only one line buffer is vacant and sub scanning and image reading are not performed. That is, the scanner 1 stops operating.

Similarly, when two or more line buffers are vacant, the sub-scanning is continuously performed the same number of times as the number of vacant lines, and the line scanning is stopped. Such an operation is repeated many times as long as the data transmission rate remains low.

[0018]

However, during such an intermittent operation of the sub-scan, specifically, an intermittent operation of a driving device which conveys an original document for the sub-scan, the sub-scan cycle is continuously performed. Due to the inertia of the entire driving device and the delay in the start-up of the motor, which is not a problem during sub-scanning, so to speak, in a steady state, the distance the document moves in the sub-scanning direction during the predetermined sub-scanning cycle It will be different for each.

This will be described with reference to FIG. 6, which shows the relationship between the sub-scanning timing during the intermittent operation and the document movement amount. In the figure, the horizontal axis of the graph is a time axis in units of the predetermined sub-scanning cycle T. The vertical axis represents the amount of movement of the document in the sub-scanning direction.

Now, in synchronism with a constant timing which continues every time T, since one line buffer is empty at the timing 2T, the drive device is restarted from the stopped state at the timing 2T. Then, the timing 3 after the time T
At T, the sub-scan is not performed because there is no space in the line buffer. Looking at the amount of original movement at this time,
The document is still moving between the timings 2T and 3T, and the movement stops between the timings 3T and 4T. The amount of movement at this time is D1. Note that this D1 is the distance that the original document should originally move per sub-scan, and the original document moves by D1 even during continuous operation rather than intermittent operation.

Now, at timing 4T, since there are two free line buffers, the driving device is restarted. Also at timing 5T, sub-scanning is performed following timing 4T. At the next timing 6T, there is no space in the line buffer, so sub-scanning is not performed. Looking at the amount of movement of the original document at this time, the movement amount of the first sub-scan for two consecutive scans, that is, the movement amount by the sub-scan at timing 4T is D2, and the second time, that is, timing 5T.
The amount of movement by the sub-scan of is D3. D2 is much smaller than D1 and D3 is much larger than D1. However, the sum of D2 and D3 is equal to twice D1. That is, the amount of movement of the document when the continuous sub-scanning is performed only twice is twice the distance to be originally moved, but the original cannot be moved in the first sub-scanning cycle T started from the stopped state. This means that only the minute is moved by the second sub-scan.

As described above, when the FIFO is chronically full of coded data, the sub-scanning is intermittently performed, and 2
The sub-scanning that continues only once, in other words, the transient state at the time of starting the drive device is also repeated many times intermittently, so the state in which the moving distance for each line is not constant occurs continuously, and it is read. There is a problem that the quality of the image deteriorates.

In order to prevent such deterioration of image quality, the capacity of the FIFO is set so that the FIFO will not be filled up regardless of the data transmission speed, that is, the processing speed of the modem 4 which is the processing device of the next stage. However, in that case, another problem that the device cost becomes high arises.

The present invention has been made in view of the above circumstances, and is a FIFO without increasing the cost of the apparatus.
It is an object of the present invention to provide an image reading device capable of reducing the deterioration of the image quality of a read image that occurs when the code is chronically full of encoded data.

[0025]

In order to achieve the above object, an image reading apparatus according to claim 1 sequentially inputs image data for each main scanning line read by a scanner into a plurality of line buffers. , The image data input to the line buffer are sequentially taken out to the processing device in the order of input and processed, and the processed image data are sequentially FIFO-processed.
In an image reading device that transfers data to a next-stage processing device via a memory, when the amount of untransferred data in the FIFO memory exceeds a predetermined upper limit amount, one line of the plurality of line buffers is used. It is characterized in that it is provided with a one-line control means for controlling so as to transfer the image data from the scanner to the processing device using only the buffer.

Further, in the image reading apparatus according to the second aspect, the image data for each main scanning line read by the scanner is sequentially input to a plurality of line buffers, while the image data input to the line buffer is input. In the image reading apparatus that sequentially fetches the processed data into the processing device in the order of input and processes the processed image data to the next processing device through the FIFO memory, the amount of untransferred data in the FIFO memory is predetermined. From the time when the amount exceeds the upper limit to the time when the amount becomes less than the predetermined lower limit, control is performed so that image data is transferred from the scanner to the processing device using only one line buffer of the plurality of line buffers. It is characterized in that it is provided with a 1-line control means.

An image reading apparatus according to a third aspect is the image reading apparatus according to the first or second aspect, in which only one line buffer among the plurality of line buffers is used to drive the scanner to the processing apparatus. When it is controlled to transfer image data to the scanner, the image is read by the scanner in the latter half of the predetermined sub-scanning cycle,
When image data is being transferred from the scanner to the processing device using the plurality of line buffers, the reading is controlled so that the image reading by the scanner is performed in the first half of the predetermined sub-scanning cycle. It is characterized in that it is provided with control switching means.

[0028]

According to the configuration of claim 1, the FIFO
When the amount of untransferred data in the memory exceeds a predetermined upper limit amount, only one line buffer of the plurality of line buffers is used to transfer the image data from the scanner to the processing device. When the untransferred data in the FIFO memory is less than the predetermined upper limit value, the image data transfer is performed using only a plurality of line buffers. When the amount of untransferred data in the FIFO memory gradually increases due to the delay in the processing of the processing device in the next stage, and the predetermined upper limit is exceeded, data transfer is actually performed using only one line buffer. To do. As a result, the image data for one main scanning line is read and transferred to the line buffer having only one line. Therefore, even if the image data of the next main scanning line is continuously read, it is transferred by that time. Successive readings are less likely to occur because there is less opportunity for the power line buffer to become empty. That is, it becomes difficult to perform continuous sub-scanning. Then, even if all the image data in the line buffer of only one line is taken out by the processing device and processed, only one line buffer is newly vacated, so the scanner repeats the same operation. In this operation state, the image reading speed is lower than that in the case where the sub-scan is continuously performed. Therefore, the time until the FIFO memory is filled with the untransferred data is greater than that in the case where all the plural line buffers are used. Becomes longer. If the processing speed of the next-stage processing device exceeds the decreased image reading speed, F
The IFO memory will not be filled with untransferred data.
Even if it is full, since there is only one line buffer, it is difficult to perform intermittent repetition of sub-scans that are continuous several times.

Further, according to the structure of the second aspect, the plurality of lines are set until the amount of untransferred data in the FIFO memory exceeds a predetermined upper limit amount and becomes equal to or less than a predetermined lower limit amount. The FIFO according to the configuration of claim 1, further comprising a one-line control unit that controls to transfer the image data from the scanner to the processing device by using only one line buffer among the buffers. When the untransferred data in the memory exceeds the predetermined upper limit amount and becomes less than or equal to the upper limit amount again, suddenly a plurality of line buffers, which had been used for transferring image data until now, are suddenly used. Therefore, the image reading speed also suddenly increases. Then, depending on the processing speed of the next-stage processing device, the F
The untransferred data in the IFO memory exceeds a predetermined upper limit,
Further, it is possible that the operation of reaching the upper limit amount or less is repeated, but in the configuration according to the second aspect, after the upper limit amount is exceeded, even if the upper limit amount is again reached, the predetermined lower limit amount is reached. Until that time, since only one line buffer is used, it is difficult for intermittent sub-scanning to occur several times in succession near the upper limit value.

According to the third aspect of the present invention, since the reading control switching means is provided, when the number of line buffers used for data transfer is only one, the image reading is performed in the sub-scanning cycle. It is much less likely that the line buffer will be vacant until the timing of the next sub-scan, which is performed in the second half, as compared with the configuration of claim 1 or 2. In addition, when data is transferred using a plurality of line buffers, that is, when images are continuously read, the image is read in the first half of the sub-scan cycle, so the timing of the next sub-scan is not reached. Since there is time to process the image data in the line buffer, the chances that the plurality of line buffers are all filled with the image data are reduced as compared with the case of reading the image in the latter half. That is, it becomes difficult to prevent continuous reading of images.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case in which the present invention is applied to a facsimile machine will be described below in detail with reference to the accompanying drawings. In the drawings referred to in the following description, the same parts as or corresponding parts to those in FIG. 5 showing an example of the configuration of a conventional facsimile apparatus are designated by the same reference numerals. In the following description of the embodiments, reference will be made to FIG.

First, referring to FIG. 1 of the first embodiment of the present invention.
Also, a detailed description will be given with reference to FIG. FIG. 1 is a block diagram of the image reading device and the next-stage processing device. The scanner 1 reads a document image and is shown in FIG.
Is similar to that shown in. Line buffer group 2
a is composed of a total of four line buffers of line buffers 1, 2, 3 and 4 each having a capacity of 256 bytes, and is arranged in a predetermined area of the RAM 2. The DCR3, which is a processing means, is for compressing the image data extracted from the line buffer group 2a to generate encoded data. The FIFO 2b temporarily stores the encoded data generated by the DCR 3, and is arranged in a predetermined area of the RAM 2 with a capacity of 2 kbytes (2048 bytes) in this embodiment. The modem 4 is a next-stage processing device, which extracts encoded data in the order input from the FIFO 2b and modulates it. The CPU 8 controls the above-mentioned units and manages various pointers and counters described later.

With the above configuration, it is shown in which of the line buffers 1, 2, 3 and 4 the image data in line units read by the scanner 1 for each main scanning line should be input. Input to the line buffer indicated by the line buffer input pointer. If the line buffer 1 is input to the line buffer 1, the line buffer input pointer indicates the line buffer 2 next. Then, the image data is transferred from the scanner 1 to the line buffer group 2a while sequentially circulating through the line buffers 3, 4, 1.

In parallel with the transfer of the image data, DCR3
Sequentially fetches and processes the line buffer image data indicated by the line buffer read pointer, which indicates which line buffer image data the DCR 3 should fetch. Assuming that the image data in the line buffer 1 is being processed, the line buffer read pointer indicates the line buffer 2 after all the processing of the image data is completed. Then, the DCR from the line buffer group 2a is sequentially cycled through the line buffers 3, 4, 1.
The image data is taken out at 3.

The line buffer counter, which counts how many line buffers have unprocessed image data, is set to 1 each time image data is transferred from the scanner 1.
DCR3 subtracts 1 every time all the image data in one line buffer is processed.

In parallel with the input and read of the line buffer, the byte-unit coded data generated by the DCR3 is stored in a FIFO input pointer indicating which address of the FIFO 2b the coded data should be stored. It is stored at the indicated address. Then, the FIFO input pointer indicates the next address each time it is stored, and the FIFO input pointer circulates like the pointer of the line buffer.

In parallel with the storing operation, the coded data stored in the FIFO 2b is indicated by a FIFO read pointer which indicates in which order the coded data stored in the FIFO 2b should be read. Read from address. The FIFO read pointer indicates the next address each time it is read, and the FIFO read pointer circulates similarly to the FIFO input pointer.

The coded data thus read is sequentially transferred to the modem 4. In addition, the FI that counts how many bytes of untransferred encoded data are present in the FIFO 2b
The FO counter is incremented by 1 each time 1 byte of coded data is transferred from the DCR 3, and decremented by 1 each time 1 byte is transferred to the modem 4.

When the FIFO 2b is filled with untransferred data, that is, when the count value of the FIFO counter reaches 2048 which is the total number of bytes of the FIFO 2b, the operation of the DCR3 is stopped. When the line buffer group 2a becomes full, that is, when the count value of the line buffer counter reaches 4, the operation of the scanner 1 is stopped.

The image reading apparatus of this embodiment which operates as described above operates according to the subroutine shown in FIG. 2 when the CPU 8 transfers the encoded data generated by the DCR 3 to the FIFO 2b. That is, the CPU 8
First, the encoded data is input to the address indicated by the FIFO input pointer (process 101). Next, 1 is added to the FIFO counter (process 102). Then, it is determined whether the count value of the FIFO counter is equal to 2048 which is the total capacity of the FIFO. (Decision 103). If they are equal, wait until they are not equal (Yes loop of decision 103). If they are not equal (No in judgment 103), it is checked whether the count value of the FIFO is equal to or larger than the predetermined upper limit amount (decision 104). This upper limit amount is set to an appropriate value in consideration of the processing speed of the next-stage processing device and whether the image reading speed is prioritized or the image quality is prioritized.

When the count value of the FIFO counter is equal to or larger than the predetermined upper limit amount (Yes in judgment 104), the 1-line control flag is turned on, and when the count value of the FIFO counter is not equal to or larger than the predetermined upper limit amount (judgment). No of 104)
Turn off the 1-line control flag. And finally FIF
The O input pointer is moved to the next address (process 107).

As described above, the 1-line control flag is ON while the amount of untransferred data in the FIFO 2b exceeds the predetermined upper limit amount. While this is ON, the CPU 8 controls the line buffer group 2a. 1 line buffer is used, and the remaining 3 are not used, from scanner 1 to DCR3
Transfer image data to.

As a result, the scanner 1 operates so that, while the 1-line control flag is ON, the sub-scan is performed only once and then the next sub-scan cycle is stopped, so that the FIFO 2b is not transferred. The chance of filling up with data is much less, and even if it fills up with untransferred data, two consecutive sub-scans occur intermittently that cause deterioration of the read image. Is almost eliminated, and deterioration of the quality of the read image can be prevented.

By the way, in the first embodiment described above,
The 1-line control flag was turned ON / OFF depending on whether or not it exceeded the predetermined upper limit amount. However, in the control by only the upper limit amount, the untransferred data amount vibrates near the upper limit amount depending on the conditions such as the processing speed of the next stage. It is possible that the ON / OFF of the 1-line control flag frequently occurs, and sub-scanning that is continuous several times occurs intermittently many times. The second embodiment solves such a problem.

In the image reading apparatus of the second embodiment, the CPU 8
The encoded data generated by the DCR3 into the FIFO2b.
When the data is transferred to, it operates according to the subroutine shown in FIG.

That is, the CPU 8 first inputs the encoded data to the address indicated by the FIFO input pointer (process 101) and adds 1 to the FIFO counter (process 10).
2) determine whether the count value of the FIFO counter is equal to 2048 which is the total capacity of the FIFO 2b (decision 103),
If they are equal, wait until they are not equal (Yes at decision 103)
s loop), if not equal (No in decision 103) FI
Until the FO count value is greater than or equal to the predetermined upper limit amount (decision 104), the process is the same as in the first embodiment. However, in the second embodiment, the FIFO counter count value is greater than or equal to the predetermined upper limit amount. If it is (Yes in judgment 104), the 1-line control flag is turned on (process 105) and the process proceeds to process 107. When the count value of the FIFO counter is not greater than or equal to the predetermined upper limit amount (No in determination 104), it is further checked whether the count value of the FIFO counter is less than the predetermined upper limit amount or less than or equal to the predetermined lower limit amount (determination). 108) and when the amount is less than or equal to the predetermined lower limit amount (Yes in determination 108), 1
When the line control flag is turned off (process 106) and is not less than or equal to the predetermined lower limit amount (No in determination 108), the process proceeds to process 107 without changing the state of the 1-line control flag. Finally, the FIFO input pointer is moved to the next address (process 107). It should be noted that this lower limit amount is set to an appropriate value in consideration of the processing speed of the next-stage processing device and the image reading speed but the image quality.

As described above, since the 1-line control flag is ON until the amount of untransferred data in the FIFO 2b exceeds the predetermined upper limit amount and becomes equal to or lower than the predetermined lower limit amount, the 1-line control flag is in the vicinity of the upper limit amount. The amount of untransferred data increases and decreases in a vibrational manner,
Sub scans that are continuous only several times do not occur intermittently many times.

According to the first and second embodiments described above, even if the FIFO 2b is filled with the untransferred data, the sub-scanning that is continuous several times occurs intermittently many times. Things almost disappear, but not at all. The third embodiment to be described next makes it more difficult to cause the sub-scanning, which has been repeated several times, as compared with the first and second embodiments, and continuously uses a plurality of line buffers for continuous image formation. It does not unnecessarily reduce the reading speed when reading.

In general, the scanner does not read an image for a predetermined sub-scanning cycle, but it reads the image in the first half or the second half of the sub-scanning cycle. The difference in operation between the former case and the latter case will be described with reference to FIG.

When an image is read within the time of 0.5T which is the first half of the sub-scanning cycle T shown in FIG. 4A, there is only one line buffer at the timing 0T, and therefore there is 1 at the timing 0T. Sub-scanning is performed twice, and an image of one line is read by the timing 0.5T and transferred to the line buffer of only one line. Then, within 0.5T until the next sub-scanning timing 1T, the DCR of the image data of the line buffer to which the image data has been transferred has been reached.
Since the processing by 3 is possible, one line buffer that was vacant at the sub-scanning timing 1T may become vacant again at the sub-scanning timing 1T. That is, even if only one line buffer is used, the sub-scan may be performed twice or more continuously. This action is used when reading images continuously using all line buffers.
That is, it is preferable in the first and second embodiments of the present invention so as not to unnecessarily reduce the reading speed while the 1-line control flag is OFF. However, while the 1-line control flag is ON, it becomes a factor of image quality deterioration when the FIFO 2b is full of untransferred data.

On the other hand, when reading at 0.5T in the latter half of the sub-scanning period T shown in FIG. 4B, there is only one line buffer at timing 0T, so there is one sub-scanning at timing 0T. Then, the reading of the image of one line is started at the timing of 0.5T, is read by the timing 1T, and is transferred to the one line buffer.
However, since the image is read just before the next sub-scanning timing 1T, the DCR 3 has no time to complete the processing of the read image data, and the sub-scanning timing 1T
, There was an empty 1 at the sub-scanning timing 0T
The book's line buffer will never be free again. That is, if only one line buffer is provided, a time period for which the sub-scanning is stopped, which is equal to or longer than the sub-scanning period T, is inserted between one sub-scanning and the next sub-scanning, and the sub-scanning is continuously performed twice or more. The sub-scan is not performed. This action does not require the reading speed when images are continuously read by using all of the plurality of line buffers, that is, while the 1-line control flag is OFF in the first and second embodiments of the present invention. It is not preferable because it lowers. However, if the 1-line control flag is O
When the FIFO 2b is filled with the untransferred data during N, the deterioration of the image quality can be reduced because the continuous sub-scanning does not occur twice or more.

Utilizing such a difference in the operation of the two read controls, the CP is used in the first and second embodiments of the present invention.
U8, as a reading control switching means, controls to read an image in the latter half of the sub-scanning cycle when the 1-line control flag is ON, and when the 1-line control flag is OFF, the sub-scanning cycle The third embodiment of the present invention controls to read an image in the latter half.

In the first, second and third embodiments of the image reading apparatus of the present invention described above, the present invention is applied to the case where the next-stage processing apparatus is a modem, that is, the facsimile apparatus. Not only the facsimile apparatus but also the next-stage processing apparatus performs some processing using the image data read by the image reading apparatus, but the processing speed becomes slower than the image reading speed of the image reading apparatus. It is needless to say that the present invention can be applied to the case where various image processing apparatuses as described above are used.

[0054]

According to the invention of claim 1, the FI
When the amount of untransferred data in the FO memory exceeds a predetermined upper limit amount, only one line buffer of the plurality of line buffers is used to transfer the image data from the scanner to the processing device. Since it has a one-line control means for controlling it to do so, the chances that the FIFO memory will be filled with untransferred data will be much less. for example,
Even if it becomes full, since there is only one line buffer, it is difficult to perform intermittent sub-scans that are repeated only several times. Therefore, the deterioration of the read image, which is apt to occur in the past due to the FIFO memory being filled with the untransferred data, does not increase the device cost,
Will be reduced.

According to a second aspect of the present invention, the plurality of line buffers are provided until the amount of untransferred data in the FIFO memory exceeds a predetermined upper limit amount and becomes equal to or less than a predetermined lower limit amount. The FIFO memory is filled with untransferred data because it is equipped with one-line control means for controlling the transfer of image data from the scanner to the processing device by using only one line buffer among them. As a result, the deterioration of the read image, which has been liable to occur in the past, is not only reduced without increasing the apparatus cost, but may occur in the invention according to claim 1.
When the amount of untransferred data in the memory is in the vicinity of the predetermined upper limit value, the intermittent repetition of the sub-scan that occurs only several times does not occur.

According to the third aspect of the invention, since the reading control switching means is provided, when only one line buffer is used for data transfer, the image reading is performed in the latter half of the sub-scanning cycle. The deterioration of the read image, which has been liable to occur in the past due to the fact that the FIFO memory is filled with untransferred data, is much reduced as compared with the invention according to claims 1 and 2, and a plurality of lines are also used. Even when data is transferred using the buffer, images can be read at a high reading speed without disturbing continuous reading of images.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an image reading apparatus according to an exemplary embodiment of the present invention and a processing apparatus of a next stage.

FIG. 2 is a flowchart showing a first embodiment of the present invention.

FIG. 3 is a flowchart showing a second embodiment of the present invention.

FIG. 4 is a diagram showing an image reading timing for explaining a third embodiment of the present invention.

FIG. 5 is a diagram showing an example of the configuration of a conventional facsimile device and also showing the configuration of a facsimile device to which the present invention is applied.

FIG. 6 is a diagram for explaining an operation when a FIFO memory is chronically filled with untransferred data in a conventional image reading apparatus.

[Explanation of symbols]

 1 Scanner 2 RAM 2a Line Buffer Group 2b FIFO 3 DCR 4 Modem 8 CPU

Claims (3)

[Claims] 1. The image data for each main scanning line read by a scanner is sequentially input to a plurality of line buffers, and the image data input to the line buffer is sequentially taken out to a processing device in the order of input. In an image reading device that sequentially processes and processes the processed image data to a next-stage processing device via a FIFO memory, when the amount of untransferred data in the FIFO memory exceeds a predetermined upper limit amount, An image reading apparatus comprising one line control means for controlling to transfer image data from the scanner to the processing apparatus using only one line buffer among the line buffers. 2. The image data for each main scanning line read by a scanner is sequentially input to a plurality of line buffers, while the image data input to the line buffer is sequentially taken out to a processing device in the order of input. In an image reading device that sequentially processes and processes the processed image data to a next-stage processing device through a FIFO memory, a predetermined lower limit amount after the amount of untransferred data in the FIFO memory exceeds a predetermined upper limit amount. Until the following, one-line control means is provided to control so that the image data is transferred from the scanner to the processing device using only one line buffer among the plurality of line buffers. An image reading device characterized by. 3. An image read by a scanner when it is controlled to transfer image data from the scanner to the processing device using only one line buffer of the plurality of line buffers. Is performed in the latter half of a predetermined sub-scan cycle, and when image data is being transferred from the scanner to the processing device using the plurality of line buffers, the scanner reads the image by the predetermined sub-scan. 3. The image reading apparatus according to claim 1, further comprising a reading control switching unit that controls to perform in the first half of the scanning cycle.