JPH09200437A - Double-sided document reader - Google Patents

Abstract

(57) Abstract: A double-sided original in which the image data of each side of a double-sided original can be encoded by a single encoder and the encoded image data for each side can be obtained without increasing the size of the device. Providing a reader. A first side for reading each side of a double-sided original
And the line data from the second reading means are alternately encoded by the encoding means, and the encoded line data is separated into the first reading means side encoded line data and the second reading means side encoded line data, By sequentially accumulating the respective encoded line data in the first and second encoded image data accumulating means, the encoded image data on one side and the encoded image data on the other side of the double-sided original are respectively obtained. It is characterized by obtaining.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided document reading device for reading both sides of a document to obtain image data for each side, and more particularly to one side of both sides of a document which is relatively sub-scanned. Image data obtained by reading in line units by the first reading unit and image data obtained by reading the other face of the document in line units by the second reading unit are coded to encode each face. The present invention relates to a double-sided document reading device for obtaining image data.

[0002]

2. Description of the Related Art In a conventional apparatus for simultaneously reading both sides of a document to be sub-scanned, as disclosed in Japanese Patent Laid-Open No. 2-124680, both sides of the document are read for each screen, so that reading is performed for each screen. It is necessary to have a section. Image data obtained by reading each side of the document is output from the reading unit for each side.

Generally, the information amount of the image data output by the reading section of the document reading apparatus is enormous, and if it is processed as it is, a memory for storing the image data and a transmission capacity for transmitting the image data. Must be secured in large quantities. Therefore, it is usually encoded to compress the information amount of the image data output by the reading unit, converted into encoded image data in page units, and the encoded image data is stored in a memory in page units or transmitted. By doing so, we are trying to save memory and transmission capacity.

[0004]

However, in the above-mentioned conventional apparatus for reading a double-sided original, when the reading portions for each side of the double-sided original are arranged with a difference within the length of the original (sub-scanning range), Since there is a period in which those reading units are reading each side of the double-sided original at the same time,
There is a period in which the image data output from each reading unit must be simultaneously encoded.

Therefore, there is a problem that two encoders are required to encode the image data from the reading unit for each surface, which increases the cost.

On the other hand, in the above-mentioned conventional apparatus for reading a double-sided original, when the reading units for each side of the double-sided original are arranged with a difference of not less than the length of the original, both sides of one double-sided original are simultaneously printed. Since there is no reading period, it is not necessary to encode the image data output from each reading unit at the same time, but because of the sub-scanning of the document that is required to cause each reading unit to read the document. However, since the transport path of the device becomes long, the device becomes large in size, and there is a problem that the cost also increases.

The present invention has been made in view of such circumstances, and the image data of each side of a double-sided original is encoded by one encoder without increasing the size of the apparatus, and the encoded image of each side is encoded. An object of the present invention is to provide a double-sided document reading device that can obtain data.

[0008]

In order to achieve the above object, a double-sided document reading device according to a first aspect of the present invention is characterized in that one side of both sides of a document that is relatively sub-scanned is lined by the first reading means. A double-sided original in which the image data obtained by reading in units and the image data obtained by reading the other side of the original in line units by the second reading unit are respectively encoded to obtain encoded image data in each side. In the reading device, the first and second reading means are provided such that their reading positions in the sub-scanning direction substantially coincide with each other across the document, while the first and second reading means sequentially output the reading positions. Line selection means for alternately switching and outputting line data for the sub-scanning range of the document, and line data output from the line selection means are sequentially encoded to obtain an encoded line data. Encoding means for outputting the data, encoding line data output from the encoding means, encoded line data read by the first reading means and encoded by the first reading means, and the second encoding means. Encoding line separating means for separating the second reading means side encoded line data read and encoded by the reading means, and first and second reading means side codes respectively separated by the encoding line separating means. First and second encoded image data accumulating means for sequentially accumulating the encoded line data to obtain the encoded image data on one side and the encoded image data on the other side of the original, respectively. Is characterized by.

According to another aspect of the present invention, there is provided a double-sided document reading device, in which image data obtained by reading one surface of both sides of a document to be relatively sub-scanned by the first reading means in line units.
In the double-sided original reading device, the other side of the original is coded with the image data obtained by reading the other side by the second reading unit to obtain the encoded image data for each side. The reading unit is provided with reading positions in the sub-scanning direction that are different from each other across the document, and includes a sub-scanning range of the document in accordance with a deviation of each reading position in the sub-scanning direction. While outputting line data for a common sub-scanning range wider than the scanning range, line selection means for alternately switching and selectively outputting line data sequentially output from the first and second reading means, and the line thereof. Of the line data for the common sub-scanning range output from the selecting means, a predetermined number of leading lines corresponding to the displacement of the arrangement position of the first and second reading means Encoding means for outputting the encoded line data by sequentially encoding only the line data included in the sub-scanning range of the document after the predetermined number of lines without outputting the encoded line data for the line data for the IN portion. The coded line data output from the coding means is coded by the first reading means and is coded by the first reading means, and the coded line data read by the second reading means is coded. The encoding line separation means for separating the encoded line data into the encoded second line data on the second reading means side, and the encoded line data on the first and second reading means sides separated by the encoding line separation means are sequentially accumulated. And a first and second encoded image data storage means for respectively obtaining encoded image data on one side of the original and encoded image data on the other side. To.

A double-sided document reading device according to a third aspect of the present invention is the double-sided document reading device according to the second aspect, further comprising head invalid line number setting means for setting the predetermined number of lines.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described in detail.

FIG. 1 shows a G3 facsimile apparatus including a double-sided document reading apparatus according to the present invention as a part of its construction.

In FIG. 1, the scanner unit 3 is for reading a double-sided original, and the contact sensors 1a and 1b for reading the front and back surfaces of the original on a line-by-line basis and the contact sensors, respectively. From a front surface reading unit 2a and a back surface reading unit 2b that binarize the read analog line signal and output line data, and a document conveying unit (not shown) that subscans the document relative to the contact sensors 1a and 1b. It is configured.

The encoding / decoding unit 4 converts the line data from the front surface reading unit 2a and the back surface reading unit 2b into MH, MR, and M.
It encodes line by line by an encoding system such as MR system and outputs encoded line data, while decoding received image data. The image memory 5 sequentially stores encoded line data encoded in line units in the encoding / decoding unit 4 and accumulates received image data to accumulate encoded image data in page units. .

The plotter 6 records and outputs the encoded image data for each page, which is decoded by the encoding / decoding unit 4 and is accumulated in the image memory 5. That is, if the encoded image data stored in the image memory 5 is received image data, the facsimile apparatus performs a recording / output operation, and the encoded image data stored in the image memory 5 is output from the scanner unit 3. If there is, a recording output operation as a copying machine is performed.

The CPU 7 controls each part of the apparatus. The ROM 8 stores the operation procedure of the CPU 7 and various data in advance. The RAM 9 stores temporary data as a work area of the CPU 7, and is interposed between the scanner unit 3 and the encoding / decoding unit 4 to buffer a variation in processing speed thereof. (This will be described later) is secured.

The modem 10 converts and demodulates a transmission / reception signal, and the network control unit 11 is for connecting a facsimile machine to a line by a predetermined procedure. The operation display unit 12 is for receiving various inputs from the user and displaying the operation status and messages of the apparatus to the user.

FIG. 2 shows a schematic configuration of the facsimile apparatus shown in FIG. 1 when viewed as a double-sided document reading apparatus according to the present invention.

In the figure, the front side reading section 2a and the back side reading section 2b respectively output the line data of the front side and the back side of one double-sided original that is sub-scanned relative to them in parallel. There is.

The line data output in parallel are read alternately by the CPU 7 from the front to the back, and are stored in the line buffer group 9a secured in the RAM 9 in the order of reading. If this operation is schematically described, as shown in FIG. 2, the CPU 7 causes the switch S to output line data output from the front surface reading unit 2a and the back surface reading unit 2b.
It can be said that W1 is alternately switched and selectively output and input to the line buffer group 9a.

The line buffer group 9a is composed of ten line buffers from line buffer 0 to line buffer 9. The write pointer Pw determines which line buffer the CPU 7 stores the line data read from the front surface reading unit 2a or the back surface reading unit 2b.
Is determined by the value of The write pointer Pw is a decimal counter that is incremented by the CPU 7 every time line data is written in the line buffer indicated by the write pointer Pw at the present time, and is 0, 1, 2, ...
When it counts up to 8 and 9, in the next count,
The carry is ignored, the value returns to 0 again, and the same count-up is repeated.

The line data stored in the line buffer group 9a are read by the CPU 7 in the order in which they are written and input to the encoding / decoding unit 4. At this time, which line buffer to read from depends on the value of the read pointer Pr. Like the write pointer Pw, the read pointer Pr is a decimal counter that is incremented by the CPU 7 each time line data is read from the line buffer indicated by the current read pointer Pr, and is 0, 1, 2, ... When the count is incremented to 8 and 9, the carry is ignored in the next count, the count returns to 0 again, and the same count up is repeated.

As described above, the front surface reading unit 2a and the back surface reading unit 2b are provided by interposing the line buffer group 9a.
While buffering the fluctuation of the processing speed with the encoding / decoding unit 4,
The front side line data and the back side line data that are alternately input to the encoding / decoding unit 4 are encoded by the encoding / decoding unit 4 and output as encoded line data.

The coded line data output from the coding / decoding section 4 is the front side coded line data obtained by coding the front side line data read by the front side reading section 2a.
The back side encoded line data obtained by encoding the back side line data read by the back side reading unit 2b is mixed, and the mixed encoded line data is the CPU 7
Are separated by the front side encoded line data and the back side encoded line data, the front side encoded line data is stored in the front side image data storage memory 5a, and the back side encoded line data is stored in the back side image data storage memory 5b. Are sequentially stored in. If this operation is schematically described, as shown in FIG. 2, by the CPU 7 switching the switch SW2, the encoded line data output from the encoding / decoding unit 4 and the encoded line data on the front side, It can also be said to be separated into the back side encoded line data and input to the front side image data storage memory 5a and the back side image data storage memory 5b, respectively.

In this way, the encoded line data sequentially output from the encoding / decoding unit 4 is separated by the front side encoded line data and the back side encoded line data,
The encoded line data is divided into the front image data storage memory 5a and the back image data storage memory 5b, respectively, and sequentially stored, so that the front image data storage memory 5a stores the encoded images of the front page of the document. The data is,
In the back side image data storage memory 5b, the coded image data of the back side page of the document is obtained.

The encoded image data for each page of the double-sided original obtained in the front side image data storage memory 5a and the back side image data storage memory 5b are transmitted to the other facsimile machine as described above. And post-processing such as recording and outputting by the plotter 6 are performed.

With the configuration shown in FIG. 2 briefly described above, the front side reading section 2a corresponds to the front and back sides of a double-sided original.
The front side line data and the back side line data respectively output from the back side reading unit 2b and the back side reading unit 2b are encoded by the encoding / decoding unit 4 which is one encoder, and then the front side encoded line data and the back side line data. Since it is separated into side encoded line data and collected into encoded image data for each of the front and back pages of a double-sided original, as in the conventional case,
Even if the reading unit for each side of the double-sided document is arranged within the sub-scanning range of the document, it is not necessary to provide two encoders corresponding to the respective reading units. Therefore, one encoder can be provided without increasing the size of the device.

Next, a specific encoding processing procedure in the double-sided document reading apparatus according to the present invention shown in FIG. 2 will be described.

The processing procedure is as follows:
Then, there are two procedures depending on the relative reading position of the document in the sub-scanning direction with respect to the back surface reading section 2b. That is, there are cases where the relative reading positions of the document in the sub-scanning direction of the front surface reading unit 2a and the back surface reading unit 2b match, and where they do not match.
The relative reading position of the front surface reading unit 2a and the back surface reading unit 2b in the sub-scanning direction is the difference between the positions in the sub-scanning direction of the main scanning lines read by the respective reading units. Is the contact sensors 1a and 1b corresponding to each reading unit.
Of the photoelectric conversion elements arranged in a line in the main scanning line direction, respectively, in the sub scanning direction. When the image sensor for reading the original is a contact sensor as in the present embodiment, the position of the photoelectric conversion element is the reading position as it is, but for other image sensors (CCD), the image sensor It can be generalized and considered as the position of the input main scanning line image in the sub-scanning direction in the document conveyance path.

FIG. 3 shows the front side reading section 2a and the back side reading section 2b.
6 shows the arrangement of the contact sensors 1a and 1b when the relative reading positions of the document in the sub-scanning direction coincide with each other. In the figure, the contact sensors 1a and 1b are arranged such that their respective reading positions 1a and 1b in the sub-scanning direction substantially coincide with each other with a document interposed therebetween. The sensor S2 provided in front of the contact sensors 1a and 1b and the sensor S1 provided further in front of the sensor S2 are included in the configuration of the scanner unit 3, and are arranged in the moving direction shown in FIG. This is a known document edge detection sensor that optically detects the leading edge and the trailing edge of the document when the document to be read moves. The sensor S1 is provided far in front of the contact sensors 1a and 1b and detects that the document to be read is approaching by detecting the leading edge of the document. When the approach is detected, the document is prepared for reading. The sensor S2 is provided in the vicinity of the contact sensors 1a and 1b, and the contact sensor 1a
1b and 1b provide a reference for allowing the reading to be accurately started from the leading edge of the document.

FIG. 4 shows the front side reading section 2a and the back side reading section 2b.
6 shows the arrangement of the contact sensors 1a and 1b when the relative reading positions of the originals in the sub-scanning direction are different from each other. In the figure, the contact sensors 1a and 1b are arranged such that their reading positions 1a and 1b in the sub-scanning direction are different from each other with a document interposed therebetween. The sensor S2 provided in front of the contact sensors 1a and 1b and the sensor S1 provided further in front of the sensor S2 are included in the configuration of the scanner unit 3, and are arranged in the moving direction shown in FIG. This is a known document edge detection sensor that optically detects the leading edge and the trailing edge of the document when the document to be read moves. The sensor S1 is provided far in front of the contact sensors 1a and 1b and detects that the document to be read is approaching by detecting the leading edge of the document. When the approach is detected, the document is prepared for reading. The sensor S2 is provided in the vicinity of the contact sensors 1a and 1b, and the contact sensor 1a
1b and 1b provide a reference for allowing the reading to be accurately started from the leading edge of the document.

First, in the double-sided document reading apparatus according to the present invention shown in FIG. 2, as shown in FIG. 3, the relative reading positions of the front side reading section 2a and the back side reading section 2b in the sub-scanning direction of the original. A specific encoding process procedure in the case of matching will be described with reference to FIGS. 5 and 6. In addition, CPU
7 performs the document reading process by controlling the scanner unit 3 in parallel with the encoding process procedure described below by way of the line buffer group 9a. The document reading process will be described below. In the description of the encoding processing procedure, it will be described as needed.

In these figures, the CPU 7 initializes various flags and the encoding / decoding unit 4 in the initialization processing 101. Then, the total number of lines Lmax indicating the sub-scanning range (the number of main scanning lines required to read the document in the sub-scanning direction) of the double-sided document to be read by the scanner unit 3 cannot be a normal document. A large tentative value FFFFH (process 102), 0 is assigned to the line number counter Cl indicating the number of lines that have been subjected to the encoding process (Scheme 103), and 0 is assigned to the read pointer Pr. (Processing 104), 1 is assigned to the front surface flag Fh (Processing 105), and the respective storage addresses of the front and back image data storage memories 5a and 5b are set to their respective initial values (Processing 106).

Then, it is checked whether or not there is data in the line buffer (decision 107). The fact that there is data in the line buffer means that the line data from the front surface reading unit 2a and the back surface reading unit 2b of the scanner unit 3 has been input to the line buffer by the document reading process and has not been encoded yet. Since there is data, it can be determined by counting the number of unprocessed line buffers and checking if the count value is 0.

While there is no data in the line buffer, it waits until there is data in the line buffer (No loop of decision 107). The line buffer may have data because the contact sensor from the position of the sensor S2 which is known in advance after the sensor S2 detects the leading edge of the document in the document reading process in which the document subscanning is sequentially performed. The surface when the document is sub-scanned by the sub-scanning width (which can be converted into the number of main scanning lines) required for the leading edge of the document to be displaced to the reading positions 1a and 1b of 1a and 1b (these positions are the same). Reading unit 2a and back side reading unit 2b
At the same time, the reading of the original is started.

When the line buffer has data in this way (Yes in decision 107), it is next checked whether the total line number LMAX has been notified from the document reading process (decision 108). This total number of lines LMAX
Is a value obtained by converting the sub-scanning width (sub-scanning range of the document) from the detection of the front end of the document to the detection of the rear end of the document in the document reading process into the number of main scanning lines.
Since the sensor S2 is in front of the contact sensors 1a and 1b, the total line number LMAX is always notified from the document reading process by the end of this encoding process.

When the total line number LMAX is notified from the document reading process (Yes in determination 108), the LMAX notified to the total line number Lmax in the encoding process is notified.
(By this, the encoding process thereafter knows the sub-scanning range of the document being read), and the routine proceeds to the judgment 110. When not notified (N of judgment 108)
In the case of o), the process moves to the judgment 110 with or without.

In the judgment 110, the CPU 7 checks whether the front surface flag Fh is 1, and if it is 1 (front surface), the processing 1
The front side encoding process from 11 to process 114 is sequentially executed, and the process proceeds to process 120. If 0 (back side), process 115
To the processing 119, the back surface encoding processing is sequentially executed, and the processing proceeds to the processing 120.

First, in the surface coding process, line data is read from the line buffer indicated by the read pointer Pr and input to the coding / decoding unit 4 to perform one-line coding (in this embodiment, the MH system is used). (Processing 111), the coded coded line data is stored in the storage address of the front image data storage memory 5a (Process 112), and the last of the coded line data newly stored in Process 112 is stored. The address next to the address of the data is updated as a new storage address (process 113).
Then, 0 is substituted for the front surface flag Fh (Processing 11
4). In the encoding process, the line data is read from the line buffer indicated by the read pointer Pr, but in the document reading process, the line data from the front surface reading unit 2a is written in the line buffer indicated by the write pointer Pw.
Line data from the back surface reading unit 2b is alternately input. In the input order, the line data from the front surface reading unit 2a comes first and the line data from the back surface reading unit 2b comes later. Therefore, also in the line data read from the line buffer, the data from the front surface reading unit 2a comes first and the data from the back surface reading unit comes later.

On the other hand, in the back side encoding process, the line data is read from the line buffer indicated by the read pointer Pr and input to the encoding / decoding unit 4 to obtain 1
Line coding (process 115) is performed, the coded coded line data is stored in a storage address of the backside image data storage memory 5b (process 116), and the last coded line data newly stored in process 116 is stored. The address next to the data address is updated as a new storage address (process 117). Then, 1 is assigned to the front surface flag Fh (process 118), and the line number counter Cl is incremented by 1 (process 119).

After the above-described front side encoding processing or back side encoding processing is performed, the read pointer Pr is incremented by 1 (step 120), and then the line number counter C is obtained.
It is checked whether the value of 1 has reached the total number of lines Lmax (decision 121). If it has reached (Yes in judgment 121), it means that the encoding has been completed for the entire sub-scanning range of the document to be encoded, and therefore the RTC code is stored in the respective storage addresses of the front and back image data storage memories. (Process 123). If not reached (N of judgment 121)
o), it is judged that the encoding has not been completed for all of the sub-scanning range of the original document to be encoded.
Returning to 07, the encoding process is repeated.

By the above encoding procedure, each line data on the front and back sides of the document in the sub-scanning range is encoded starting from the front side line data and then the front side line data and the back side line data in this order. , The front side encoded line data and the back side encoded line data that have been encoded are front and back side image data storage memories 5a and 5 respectively.
Then, the encoded image data for each of the front and back pages is finally stored in the front and back image data storage memories 5a and 5b.

FIG. 7 shows the processing order of each line data on the front and back surfaces of the original in the sub-scanning range, which is processed by the above encoding procedure. In the above coding procedure, the front side line data is processed first, and the back side data is processed next. However, whether the front side or the back side is simply a symbolic meaning for distinguishing each side of a double-sided original. Needless to say, since it has only that, it can be processed in the reverse order.

Next, in the double-sided document reading apparatus according to the present invention shown in FIG. 2, as shown in FIG. 4, the relative reading position of the document in the sub-scanning direction between the front side reading section 2a and the back side reading section 2b is determined. A specific encoding processing procedure when different is described with reference to FIGS. 8 and 9. The CPU 7 performs the document reading process by controlling the scanner unit 3 in parallel with the encoding process procedure described below by way of the line buffer group 9a. Regarding the document reading process, In the following description of the encoding procedure,
I will explain from time to time.

In these figures, the CPU 7 initializes various flags and the encoding / decoding unit 4 in the initialization processing 201. Then, the total number of lines Lmax indicating the sub-scanning range (the number of main scanning lines required to read the document in the sub-scanning direction) of the double-sided document to be read by the scanner unit 3 cannot be a normal document. Substitute a temporary value FFFFH, which is a large value (process 202), and set the value L to the surface line number counter Clh.
Substituting a (process 203), the back side line number counter Cl
The value Lb is substituted for u (processing logic 204). The value La
And Lb are, as shown in FIG. 4, the document edge detection sensor S2.
From the read position 1 of the contact sensors 1a and 1b in the sub-scanning direction
It is a value obtained by converting the distances to a and 1b into the number of main scanning lines required to perform sub-scanning by that distance, and it is a value to know in advance.

Then, 0 is assigned to the front surface addition flag Fkh (process 205), 0 is assigned to the back surface addition flag Fku (process 206), and 0 is assigned to the above-mentioned read pointer Pr (process 207) to obtain the front surface flag. 1 is substituted for Fh (process 208), and the storage addresses of the front and back image data storage memories 5a and 5b are set to their respective initial values (process 209).

Then, it is checked whether or not there is data in the line buffer (decision 210). The fact that there is data in the line buffer means that the line data from the front surface reading unit 2a and the back surface reading unit 2b of the scanner unit 3 has been input to the line buffer by the document reading process and has not been encoded yet. Since there is data, it can be determined by counting the number of unprocessed line buffers and checking if the count value is 0.

While there is no data in the line buffer, it waits until there is data in the line buffer (No loop of decision 210). The line buffer may be in a state of having data in the original reading process in which the sub-scanning of the original is sequentially performed when the sensor S2 detects the leading edge of the original in the front reading unit 2a and the back reading unit 2b at the same time. After starting to read.

When the line buffer has data in this way (Yes in judgment 210), it is next checked whether or not the total number of lines LMAX has been notified from the document reading process (judgment 211). This total number of lines LMAX
Is a value obtained by converting the sub-scanning width (sub-scanning range of the document) from the detection of the front end of the document to the detection of the rear end of the document in the document reading process into the number of main scanning lines.
Since the sensor S2 is in front of the contact sensors 1a and 1b, the total line number LMAX is always notified from the document reading process by the end of this encoding process.

When the total line number LMAX is notified from the document reading process (Yes in determination 211), the LMAX notified to the total line number Lmax in the encoding process is notified.
(By this, the encoding process thereafter knows the sub-scanning range of the document being read), and the process proceeds to the determination 213. When not notified (N of judgment 211)
In the case of o), the process moves to the determination 213 with or without.

In the determination 213, the CPU 7 checks whether the front surface flag Fh is 1, and if it is 1 (front surface), the determination 2
The front surface encoding processing after 14 is sequentially executed and then the processing proceeds to step 232. If the value is 0 (back surface), the back surface encoding processing after determination 223 is sequentially executed and then the processing proceeds to processing 232.

First, in the surface encoding processing, it is checked whether the surface line number counter Clh is 0 (decision 214), and 0 is determined.
If not (No in determination 214), it is further checked whether the front surface addition flag Fkh is 1 (determination 215), and if 1 (Yes in determination 215), the process proceeds to determination 235 and if it is not 1 (No in determination 215). ), The surface line number counter Clh is counted down by 1 (process 222), and process 232
Move on to

If the front surface line number counter Clh is 0 (Yes in judgment 214), 1 is substituted into the front surface addition flag Fkh (step 216), and then the front surface line number counter C is obtained.
It is checked whether lh has reached the total number of lines Lmax (decision 235), and if it has already been reached (Yes in decision 235).
Moves to process 232. If it has not reached yet (decision 2
No. 35) reads the line data from the line buffer indicated by the read pointer Pr, and the encoding / decoding unit 4
1-line encoding (in the present embodiment, the MH system is assumed) (processing 217) and the encoded line data thus encoded is stored in the storage address of the surface image data storage memory 5a. (Process 218), Process 2
The address next to the address of the last data of the encoded line data newly stored in 18 is updated as a new storage address (process 219). Then, the front surface flag Fh
0 is substituted for (process 220), and the surface line number counter C
lh is incremented by 1 (process 221) and the process moves to step 232. In the encoding process, the line data is read from the line buffer indicated by the read pointer Pr, but in the document reading process, the write pointer Pw.
The line data from the front surface reading unit 2a and the line data from the back surface reading unit 2b are alternately input to the line buffer indicated by. In the input order, the line data from the front surface reading unit 2a comes first and the line data from the back surface reading unit 2b comes later. Therefore, also in the line data read from the line buffer, the data from the front surface reading unit 2a comes first and the data from the back surface reading unit comes later.

On the other hand, in the back side encoding process, it is checked whether the back side line number counter Clu is 0 (determination 22).
3), if it is not 0 (No in decision 223), it is further checked whether the back surface addition flag Fku is 1 (decision 224), and if it is 1 (Yes in decision 224), the process proceeds to decision 236, and if it is not 1 ( Judgment 224 No), rear surface line number counter C
The lu is counted down by 1 (process 231) and the process moves to step 232.

If the back surface line number counter Clu is 0 (Yes in judgment 223), 1 is substituted into the back surface addition flag Fku (process 225), and then the back surface line number counter C
It is checked whether or not lu has reached the total number of lines Lmax (decision 236), and if already reached (Yes in decision 236).
Moves to process 232. If it has not reached yet (decision 2
No of 36) reads the line data from the line buffer indicated by the read pointer Pr, and the encoding / decoding unit 4
1-line encoding by inputting
6) The encoded coded line data is stored in the storage address of the backside image data storage memory 5b (process 22).
7), the address next to the address of the last data of the encoded line data newly stored in the process 227 is updated as a new storage address (process 228). Then, 1 is assigned to the front surface flag Fh (processing 229), and the back surface line number counter Clu is incremented by 1 (processing 23).
0) and the process moves to step 232.

After the above-mentioned front surface encoding processing or back surface encoding processing is performed, the read pointer Pr is incremented by 1 (processing 232), and then both the values of the front surface line number counter Clh and the back surface line number counter Clu are determined. Has reached the total number of lines Lmax (decision 23
3). If it has reached (Yes in judgment 233), it means that the encoding has been completed for all of the respective sub-scanning ranges on the front and back sides of the document to be encoded, so that the respective storage addresses of the front and back image data storage memories are stored. RTC
The code is stored (process 234). If not reached (No in the determination 233), it means that the encoding of both or any one of the sub-scanning ranges of the front and back surfaces of the original to be encoded has not been completed yet, so the determination 210.
Then, the encoding process is repeated.

Through the above encoding procedure, the document edge detection sensor S2 detects the leading edge of the document to be read, and at the same time, the reading by the front surface reading section 2a and the back surface reading section 2b is started. On the front side of the document, for the main scanning lines of the number La of main scanning lines after the start of reading, those line data are invalid line data that do not belong to the sub-scanning range on the front side of the document. Then, the line data for the total number of lines LMAX belonging to the sub-scanning range on the front side of the document is sequentially encoded after the main scanning lines for the number La of main scanning lines are discarded without being encoded. Thus, the encoded image data on the front side of the document is obtained.

On the other hand, with respect to the main scanning lines of the number Lb of main scanning lines after the reading is started on the back side of the document, those line data are invalid because they do not belong to the sub scanning range on the back side of the document. Line data for the total number of lines LMAX belonging to the sub-scanning range on the back side of the document after the main scanning lines of the number Lb of main scanning lines are discarded without being encoded as line data and sequentially encoded Then, the encoded image data on the back side of the document is obtained.

Until all the line data for the total number of lines LMAX respectively belonging to the front side and the back side of the original document are all coded, they belong to the one side of the original document. Even after the encoding of the line data for the total number of lines LMAX is completed, on the one surface side,
Since invalid main scanning lines following the sub-scanning range of the document are continuously read and only valid line data is encoded by determining whether the line data read in the encoding process is valid or invalid, The symmetry of the reading process on the front surface side and the back surface side can be maintained.

FIG. 10 shows a common sub-scanning range including the sub-scanning range of an original processed by the above encoding procedure and wider than the sub-scanning range of the original in the front surface reading section 2a and the back surface reading section 2b. The processing order of each line data on the front and back sides obtained by reading is shown.

In the figure, for the line data on the front side, the line data for the main scanning lines from the beginning to La-1 are invalid dummy data, and the line data from La to LMAX + La are: This is valid line data that belongs to the sub-scanning range of the document, and LMA
X + La + 1th to LMAX + Lb are dummy data read for reading the entire sub-scanning range on the back side of the document.

Regarding the line data on the back surface side, the line data for the main scanning lines from the beginning to the Lb−1th is invalid dummy data, and the Lbth to LMAX.
The line data up to the + Lbth line is valid line data belonging to the sub-scanning range of the document. Since Lb> La, if the entire sub-scanning range on the back side of the document is read, the reading of the sub-scanning range on the front side of the document has already been completed at that time. After the reading of the sub-scanning range is completed, it is not necessary to read the dummy data in accordance with the reading of the sub-scanning range on the front side of the document.

As described above, even if the reading positions of the contact sensors 1a and 1b cannot be arranged at the same position with the original sandwiched between them due to the arrangement of parts, one encoder can read each side of a double-sided original. Since it is possible to obtain the encoded image data for each surface by encoding the line data from the section,
The degree of freedom in arranging parts can be increased.

In the procedure shown in FIG. 8, La as the initial value of the front surface line number counter Clh and Lb as the initial value of the back surface line number counter Clu are fixed as known values. Their values La and Lb
4 corresponds to the respective distances between the document edge detection sensor S2 and the contact sensors 1a and 1b as shown in FIG. 4, the document edge detection sensor S2 and the contact sensor 1a are provided for each device.
If there is a variation in the respective distances from the positions 1 and 1b (such a variation is likely to occur due to a variation in the component mounting position for each device during device assembly), the values La and L
If b is fixed, those values La and Lb
Of the document edge detection sensor S2 and the contact sensors 1a and 1b
It may not correspond to the respective distances between and, and some of the leading edge and the trailing edge of the document may be unreadable.

On the other hand, the document edge detection sensor S2 for each device,
If the variations in the distances from the contact sensors 1a and 1b are suppressed to be small, the work of assembling the parts with high accuracy is required, and the cost of the apparatus increases.

To solve such a problem, the value L
It suffices that a and Lb be variable for each device instead of being fixed. That is, for example, the value La
RA, which is a rewritable memory for the storage areas of L and Lb
The storage addresses secured on the M9 and indicating their storage areas are input by the user from the operation display unit 12, and
The values La and Lb may be rewritten by inputting a value to be stored in the storage area indicated by the storage address and further by inputting a rewrite permission command for the values La and Lb.

By doing so, the user can obtain the values La and L.
By executing the encoding procedure shown in FIGS. 8 and 9 while rewriting b, the image data of the double-sided original read by the scanner unit 3 is encoded, and the encoded image data is plotted by the plotter 6.
By recording and outputting on both sides of the document and comparing the scanned double-sided document with the one on which the scanned image data was recorded and output, it is possible to confirm whether the document is scanned without cutting the leading edge or trailing edge of the document. Since the values La and Lb suitable for the assembling state can be set for each device, it is not necessary to assemble parts with high precision, and the device cost can be reduced.

In the encoding of the line data in the encoding / encoding unit 4 of the double-sided original reading apparatus according to the embodiment of the present invention described above, the MH system is used in which the encoding can be performed only on the encoding target line. Although the coding is performed, the coding is not limited thereto, and coding by the MR or MMR coding method is also possible.
However, in that case, it is necessary to refer to not only the encoding target line but also the line immediately before the encoding target line. That is, when the encoding / decoding unit 4 encodes the line data stored in the line buffer having the value indicated by the read pointer Pr at the current point in the line buffer by the MR or MMR encoding method, the read operation is performed. Pointer P
It is necessary to reference and encode the line data stored in the line buffer that is two values before the value indicated by r. Because
The line data stored in the previous line buffer is
This is because it is line data of a different surface from the line data stored in the line buffer having the value indicated by the read pointer Pr at the current point.

Further, in the above-described embodiment of the present invention, the case where the present invention is applied to the facsimile device has been described. However, the present invention is not limited to this, and other document reading devices such as a copying machine and a scanner. Can be similarly applied to.

[0070]

According to the first aspect of the present invention, the reading positions in the sub-scanning direction are sequentially output from the first and second reading means which are arranged so as to substantially match each other across the document. The line data for the sub-scanning range of the document is alternately switched by the line selection means, is selectively output, is input to the encoding means, is sequentially encoded, and is output as encoded line data. And
The encoded line data output from the encoding means is
The coded line separation means reads the coded line data by the first reading means and is coded by the first reading means, and the code read by the second reading means and coded by the second reading means. Is separated into
The separated encoded line data on the side of the first and second reading means is sequentially accumulated in the first and second encoded image data accumulating means, respectively, so that the encoded image data on one side of the original document is obtained. And the encoded image data of the other surface are obtained. Therefore, since a double-sided document can be read with the sub-scanning amount having the same width as when reading a single-sided document, the size of the device does not increase and one encoder encodes image data on each side of the double-sided document. Since the coded image data for each surface can be obtained by converting the data into a single-sided document reading apparatus, a low-cost double-sided document reading apparatus can be realized.

According to the second aspect of the invention, the reading positions of the respective reading positions in the sub-scanning direction are different from those of the first and second reading means provided at different positions with the original document sandwiched therebetween. Line data for a common sub-scanning range that includes the sub-scanning range of the original document and is wider than the sub-scanning range of the original document is output according to the deviation in the sub-scanning direction. It is switched, selectively output, and input to the encoding means. The encoding means includes a predetermined predetermined number of lines corresponding to the deviation of the reading position of the first and second reading means in the sub-scanning direction from the input line data for the common sub-scanning range. No encoded line data is output for the line data, and only the line data included in the sub-scanning range of the document after the predetermined number of lines are sequentially encoded and output as encoded line data. The encoded line data output from the encoding unit is encoded line data read by the first reading unit and encoded by the encoding line separation unit, and the encoded line data on the first reading unit side and the second line. The first reading section is separated into the second reading section side encoded line data read and encoded by the reading section, and the separated first section
And the coded line data on the side of the second reading means are sequentially stored in the first and second coded image data storage means, respectively, so that the coded image data on one side of the original and the code on the other side of the original are coded. Each of the chemical image data is obtained. Therefore, even if the arrangement positions of the first and second reading means are deviated in the sub-scanning direction due to the arrangement of parts, the line data of a predetermined predetermined number of lines corresponding to the deviation is not encoded. Then, the image data on each side of the double-sided original is encoded by one encoder as in the double-sided original reading apparatus according to claim 1, by discarding the line data and encoding only the line data belonging to the sub-scanning range of the original. Since it is possible to obtain the coded image data for each of the surfaces, it is possible to obtain the same effect as that of the double-sided document reading apparatus according to the first aspect, while increasing the degree of freedom of component arrangement.

According to the third aspect of the present invention, the head invalid line number setting means sets the head of the first and second reading means, which should be set according to the actual deviation of the reading position in the sub-scanning direction. Since it is possible to arbitrarily set the predetermined number of lines indicating how many lines of line data are to be discarded without being encoded, the reading in the sub-scanning direction of the first and second reading means is caused by the variation of the assembly position for each device. Even if the displacement amount of the position varies from device to device, the variation in the displacement amount can be easily corrected by changing the setting of the predetermined number of lines. That is, it is not necessary to keep the deviation amount of the reading position constant and highly accurate for each device in order to prevent the leading edge or the trailing end of the original from being damaged. It can be reduced as compared with the document reading device.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic block configuration diagram of a double-sided document reading device according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a mutual positional relationship between a document edge detection sensor and a contact sensor for each side of a double-sided document in the double-sided document reading device according to the embodiment of the present invention.

FIG. 4 is another schematic diagram showing a mutual positional relationship between a document edge detection sensor and a contact sensor for each side of a double-sided document in the double-sided document reading device according to the embodiment of the present invention.

5 is a flowchart showing an encoding processing procedure of the double-sided document reading apparatus according to the present invention when the contact sensors for each side of a double-sided document are arranged as shown in FIG.

FIG. 6 is a flowchart showing an encoding process procedure of the double-sided document reading apparatus according to the present invention in the case where the contact sensor for each side of the double-sided document is arranged as shown in FIG. 3 together with FIG.

FIG. 7 is a diagram showing a processing order of line data processed by the encoding processing procedure shown in FIGS. 5 and 6;

8 is a flowchart showing an encoding processing procedure of the double-sided document reading apparatus according to the present invention when the contact sensor for each side of the double-sided document is arranged as shown in FIG.

9 is a flowchart showing an encoding processing procedure of the double-sided document reading apparatus according to the present invention in the case where the contact sensor for each side of the double-sided document is arranged as shown in FIG. 4 together with FIG.

FIG. 10 is a diagram showing a processing order of line data processed by the encoding processing procedure shown in FIGS. 8 and 9;

[Explanation of symbols]

 1a, 1b Contact sensor 2a Front-side reading unit 2b Back-side reading unit 3 Scanner unit 4 Encoding / decoding unit 5 Image memory 5a Front-side image data storage memory 5b Back-side image data storage memory 6 Plotter 7 CPU 8 ROM 9 RAM 9a Line buffer group 10 Modem 11 Network control unit 12 Operation display unit 13 System bus S1, S2 Document edge detection sensor SW1, SW2 switch

Claims (3)

[Claims] 1. Image data obtained by reading one surface of both sides of an original that is relatively sub-scanned by the first reading means in line units, and the other surface of the original by the second reading means. In a double-sided document reading device that obtains coded image data for each side by encoding image data obtained by reading in line units, the first and second reading means include reading positions in respective sub-scanning directions. Are arranged so as to be substantially coincident with each other across the original document, and line selection for alternately outputting and selectively outputting line data for the sub-scanning range of the original document sequentially output from the first and second reading means, respectively. Means and
Encoding means for sequentially encoding the line data output from the line selecting means to output encoded line data, and encoded line data output from the encoding means can be read by the first reading means. Encoding line separating means for separating the encoded first reading means side encoded line data and the second reading means side encoded line data read and encoded by the second reading means, and the code thereof. The first and second reading means side encoded line data separated by the encoded line separating means are sequentially accumulated to obtain encoded image data on one side of the original and encoded image data on the other side. A double-sided document reading device comprising first and second coded image data accumulating means for obtaining. 2. Image data obtained by reading one surface of both sides of a document that is relatively sub-scanned by the first reading means in line units, and the other surface of the document by the second reading means. In a double-sided document reading device that obtains coded image data for each side by encoding image data obtained by reading in line units, the first and second reading means include reading positions in respective sub-scanning directions. Are arranged in mutually different positions with the original document sandwiched therebetween, and a common sub-scanning range wider than the sub-scanning range of the original document includes the sub-scanning range of the original document according to the deviation of each reading position in the sub-scanning direction. Line data which is output while the line data sequentially output from the first and second reading means are alternately switched and selectively output. Of the line data for the common sub-scanning range, the encoded line data is output for the line data for a predetermined number of lines at the beginning according to the displacement of the arrangement positions of the first and second reading means. Without encoding, the encoding means for sequentially encoding only the line data included in the sub-scanning range of the original after the predetermined number of lines and outputting the encoded line data, and the encoded line data output from the encoding means. Is read by the first reading means and encoded.
Encoding line separating means for separating the reading means side encoded line data and the second reading means side encoded line data read and encoded by the second reading means, and the encoding line separating means, respectively. First and second coded line data on the first and second reading means sides, which are separated from each other, are sequentially accumulated to obtain coded image data on one side and coded image data on the other side of the original. And a coded image data accumulating unit. 3. The double-sided document reading apparatus according to claim 2, further comprising head invalid line number setting means for setting the predetermined number of lines.