JPH07212525A - Reader - Google Patents

Abstract

PURPOSE:To provide a reader which can obtain a satisfactory read picture while the scanning speed of an image scanner is held constant even in a through up period. CONSTITUTION:At the time of starting the feeing of an original, the feeding of the original by a motor 22 in an auxiliary scanning direction is set to 1/4 of regular speed and read data for one line is obtained by main scanning for four times by the image scanner 12. Thus, the feeding of the original by the motor 22 is synchronized with the reading of the original by the image scanner 12. At that time, a data arithmetic circuit 16 executes logical operation and obtains data corresponding to one picture element in a present line based on picture element data in a previous line, which is held by a shift register 18, and binary data by main scanning for four times by the image scanner 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reading device used for reading a document in a facsimile device or the like.

[0002]

2. Description of the Related Art In a reading device such as a facsimile, a method is adopted in which information of a document is photoelectrically converted and electrically read by an image scanner such as a CCD while feeding the document by a motor. In this type of reading device, a stepping motor is used as a motor for feeding a document, and the document is fed at a constant speed from the start. The stepping motor and the image scanner are synchronized by synchronizing the time for main scanning one line of information by the image scanner with the feeding speed of the original for one line by the stepping motor.

In this type of reading device, a higher reading speed is required. In order to meet this demand, it is necessary to increase both the scanning speed of the image scanner and the document feeding speed, but the scanning speed of the image scanner can be easily increased by improving the performance of the CCD. It was difficult to start the motor at high speed. For this reason, so-called acceleration drive (through-up drive) has been adopted in which the motor is driven at a low speed at the start and then switched to the high speed drive, that is, the stepping motor is accelerated stepwise.

When this slew-up drive is adopted, the speed of feeding the original by one line becomes low while the low-speed driving by the slew-up is performed, and the speed of feeding the original and the speed of scanning the original by one line are reduced. Will be out of sync with. As a result, the number of lines read becomes larger than the number of lines sent from the document, for example,
When the read data is transferred to the recording device and recorded, there arises a problem that an image is formed by extending the read area in the sub-scanning direction at the time of through-up. For this reason, conventionally, in order to maintain synchronization with the image scanner even when the speed of the motor is changed, a method has been adopted in which the scanning speed of the image scanner is switched to a low speed while the motor is driven at a low speed.

[0005]

However, in the conventional method, the level adjusting circuit is required to change the scanning speed of the image scanner as described above. That is, for example, when the scanning speed of the image scanner is doubled, the charge accumulation time in photoelectric conversion is halved and the level of the read image signal decreases, so even if the scanning speed of the image scanner is changed A level adjustment circuit has become essential in order to keep the signal level constant. However, even if this level adjusting circuit is used, before and after the switching timing of the scanning speed of the image scanner, the image signal photoelectrically converted at a low speed (for example, 10 ms) immediately before switching is stored at high speed after switching. For example, in order to take out in 5 ms, only one scanning is performed at the level set for low speed (that is, 10 ms is accumulated in 10 ms).
At the level for judging whether the image signal taken out in is white or black, or at the level set for high speed (that is, the level for judging whether the image signal accumulated in 5 ms and taken out in 5 ms is white or black). As a result, the gray part of the original corresponding to the one scan that should be judged to be white is judged to be black and horizontal lines are generated in the image, and conversely the gray part to be judged to be black is white. It was judged that there was a problem such as a white horizontal line in the black line.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to obtain a good read image while keeping the scanning speed of the image scanner constant even during the slew-up period. The object of the present invention is to provide a reading device capable of reading.

[0007]

In order to achieve the above-mentioned object, the reading apparatus of the present invention has an image scanner for reading data by main-scanning a document, and a motor for feeding the document in the sub-scanning direction. The original is fed by the motor in the sub-scanning direction at a constant speed, and the M of the image scanner is moved.
The reading data for one line is obtained by (integer) times of main scanning, and at the same time the original feeding by the motor in the sub-scanning direction is set to M / N (M <N) of the steady speed,
A reading device for obtaining read data for one line by N (integer) main scans of the image scanner, further comprising data holding means for holding read data of pixels in the immediately preceding line in the sub-scanning direction, and the motor. Is a data calculation means for calculating data corresponding to one pixel of the current line when the feeding speed of the data is set to 1 / N, and the pixel data of the immediately preceding line held in the data holding means,
And a data calculation unit for performing theoretical calculation on the basis of data obtained by N times of main scanning by the image scanner to obtain data corresponding to the one pixel.

[0008]

In the reading apparatus constructed as described above, when the feeding of the original is started, the feeding of the original in the sub-scanning direction by the motor is set to M / N of the steady speed, and at the same time the image scanner is operated N times. By obtaining the read data for one line by the main scanning, the feeding of the original by the motor and the reading of the original by the image scanner are kept in synchronization. At this time, the data calculation means performs theoretical calculation on the data corresponding to one pixel of the current line based on the pixel data of the previous line held in the data holding means and the data of N times of main scanning by the image scanner. Ask. As described above, in the reading device of the present invention, even when the motor is started at a low speed, it is possible to maintain the synchronization between the document feeding speed by the motor and the scanning of the image scanner. Further, since the data corresponding to one pixel on the current line is obtained by the theoretical calculation using the pixel data on the immediately preceding line, a good read image can be obtained.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an electrical configuration of a reading device according to an embodiment of the present invention. The reading control circuit 20 sends a drive pulse of the image sensor to the image scanner 12, and sends a drive pulse to the motor 22 in synchronization with the drive pulse.
It is configured to send out bit control signals (SEL1, SEL2).

The image scanner 12 is composed of a one-dimensional image sensor having 1728 pixel reading pixels corresponding to one line of an A4 size document, and the reading control circuit 2
Driven by drive pulses from 0, the original is read while photoelectrically converting it in pixel units in the main scanning direction. The reading speed of the image scanner 12 is 5 msec per scanning, and the read analog signal corresponding to the original image is continuously output. The read analog signal output is
It is compared with the set level by the binarization circuit 14, converted into binary data, and sequentially sent to the data operation circuit 16.

The data operation circuit 16 reads the binary data from the binarization circuit 14 during the steady speed of the motor 22 and outputs a 2-bit control signal (SEL1,
Based on SEL2), it is directly output as read data. On the other hand, the data operation circuit 16 is provided with the binarization circuit 1 during the slew-up period of the motor 22, as described later.
Based on the binary data from 4 and the reference data from the shift register 18, a data operation designated by a 2-bit control signal (SEL1, SEL2) from the read control circuit 20 is performed, and the operation result is read data. Output as. This read data is also input to the shift register 18. The shift register 18 is a register that holds read data corresponding to 1728 pixels described above, that is, one scan, and delays the input read data by one scanning time (5 msec) and returns it to the data arithmetic circuit 16 side.

The motor 22 for feeding the original is composed of a four-phase stepping motor, and its speed is controlled by the A, B, C, and D phase drive pulses from the reading control circuit 20. The control system of this motor 22 is a 2-2 phase excitation system,
The document can be sent in 1 line in 4 steps.
When a drive pulse of 0 pps is given, the one line is 5
Send in msec.

In the reading apparatus of this embodiment, the motor 22 is driven through in order to increase the reading speed. That is, first, the motor 22
Is started, and then the speed is gradually increased to one-third of the speed, and then the motor 22 is driven at a steady speed.

That is, in synchronization with one scanning time (5 msec) of the image scanner 12, a drive pulse of 800 pps is given to the motor 22 so as to feed the original by one line at a constant speed (that is, at 5 msec). (1 line is sent), and when the motor 22 is started, a drive pulse of 200 pps is given to start from a speed of 1/4 of the steady speed (that is, 1 line is sent in 20 msec), and then 267 pp.
The driving pulse of s is given to increase the speed to one-third of the steady speed (that is, one line is sent in 15 msec), and then
The motor 22 is driven at the steady speed. At this time, the reading control circuit 20 maintains a synchronous relationship with the document feeding speed (which can be changed stepwise) by the motor 22 while fixing the main scanning time of information by the image scanner 12 to 5 msec.

The synchronous relationship between the feed speed of the motor 22 and the scanning of the image scanner 12 will be described in more detail with reference to FIG. FIG. 3 is a binary data group D11, D12 ... In which the analog signal read from the image scanner 12 is digitized by the binarizing circuit 14 in the reading apparatus of the present embodiment, and A, B to the motor 22.
6 is a timing chart showing the relationship with C- and D-phase drive pulses. The reading control circuit 20 includes the image scanner 12
A driving pulse is applied to the document to repeat scanning of the document at a constant cycle (5 msec), whereby binary data groups D11, D12 ... For one scan are output from the binarization circuit 14 at a cycle of 5 msec. At this time, the reading control circuit 20 applies A, B, C, and D phase drive pulses to the 2-2 phase excitation type motor 22 to rotate the motor 22.

As described above, first, at the time of starting the motor, a drive pulse of 200 pps, which is a quarter of the steady speed, is applied, and one line is sent in 20 msec. During this time, the image scanner 12 scans four times. The binary data groups for each scan in the four scans are converted to D11, D12, D13, D
14, the data operation circuit 16 performs an operation on the basis of these four binary data groups to obtain read data for one line. Although FIG. 3 shows only the case where four binary data groups (that is, one line) are obtained, this 200 pps slew-up drive is performed for eight lines.

Next, in order to accelerate the motor 22, a drive pulse of 267 pps, which is one-third of the steady speed, is applied for 15 ms.
Send one line with ec. During this time, the image scanner 12 scans three times, and two times each scan in the three scans is performed.
The value data group is D21, D22, D23, and these 3
Based on one binary data group, the data operation circuit 16 performs an operation as described later to obtain read data for one line. In FIG. 3, three binary data groups (that is, one line)
However, this 267 pps slew-up drive is performed for 8 lines.

Thereafter, the motor 2 is further accelerated to a steady speed.
Drive pulse of 800pps to send 2
Send lines. The image scanner 12 scans once every one line is sent in 5 msec.
The value data is directly output as read data from the data calculation circuit 16 as described later. In the reading apparatus of this embodiment, for example, every time the memory 22 (not shown) becomes full and the motor 22 is stopped to interrupt the reading of the original, the motor 22 is started by the above-mentioned slew-up drive and then the steady speed is reached. Scan the original with.

Next, the data arithmetic processing in the slew-up period of this embodiment will be described with reference to FIGS. 2, 3, 4, and 5. FIG. 2 is a data operation circuit 1 shown in FIG.
6 is a circuit diagram showing a specific configuration of No. 6. Data operation circuit 1
6 is an AND circuit 52, an OR circuit 54, and a selector 5
It is composed of 0 and 0. The read data from the binarization circuit 14 is supplied to the A terminal of the selector 50 and the AND circuit 52.
Is input to one terminal and one terminal of the OR circuit 54. Further, the output from the shift register 18, that is, the output obtained by delaying the output from the data operation circuit 16 by one scanning time (5 msec) by the shift register 18 is ANDed.
The other inverted terminal of the circuit 52 and the OR circuit 54
To the D terminal of the selector 50. The output of the AND circuit 52 is input to the B terminal of the selector 50, and the output of the OR circuit 54 is input to the C terminal of the selector 50. The selector 50 selects the data input to the A, B, C and D terminals based on the 2-bit control signals SEL1 and SEL2 from the read control circuit 20 and outputs it from the X terminal.

FIG. 4 and FIG. 5 are diagrams schematically showing the positional relationship of the read pixels related to the calculation on the original, and FIG. 4 corresponds to one line by scanning at 200 pps and four times of scanning. FIG. 5 shows a case where four binary data are obtained, and FIG. 5 shows a case where three binary data corresponding to one line are obtained by driving at 267 pps and scanning three times. X represents the pixel read data of the current line, and x in FIG.
1, x2, x3, and x4 represent binary data from the binarization circuit 14 obtained by scanning four times, and x in FIG.
1, x2, and x3 represent binary data from the binarization circuit 14 obtained by scanning three times. Further, Y represents read data on the line immediately before X in the sub-scanning direction. Note that this X is the binary data x1, x2,
It is a value obtained by a theoretical calculation described later based on x3 and x4.

In this reading device, the data operation circuit 16 shown in FIG. 2 outputs the output of the shift register 18 (corresponding to Y in this case) and the binary data of the binarization circuit 14 (here, x1, x2, x3, x4 or x1, x2, x
3) is used to determine the value of the read data X by the theoretical calculation of inverted Y · x2 + x3. In this embodiment, black data is "1" and white data is "0".

Here, first, the motor 22 shown in FIG. 3 is driven at 200 pps and four scans are performed to generate binary data groups D11, D12, D13, D14 (here, binary data x1, respectively). x2, x3, and x4 are obtained), a theoretical calculation for determining read data from these four binary data will be described. When the binary data belonging to x1 is output from the binarization circuit 14 (included in the binary data group D11 of FIG. 3), the read control circuit 20 outputs <0,0> as the control signals SEL1 and SEL2.
Then, the selector 50 outputs the output from the shift register 18 input to the D terminal (the shift register 18 reads the read data one line before, that is, the read data on the line immediately before X and the sub-scanning direction). Since Y is held, the output Y) is output from the X terminal as it is.
As a result, the output Y from the shift register 18 is input to the shift register 18 again as reference data.

Next, when the binary data belonging to x2 is output from the binarization circuit 14, the binary data group D1 in FIG.
2), the read control circuit 20 controls the control signal SEL.
<1,0> is output as 1 and SEL2.
The selector 50 outputs the input (that is, AN
The output of the inverted circuit Y * x2 calculated by the D circuit 52) is output from the X terminal. As a result, the output Y of the shift register 18 is inverted and inverted Y and x.
The theoretical product with 2 is input to the shift register 18 side.

Furthermore, when the binary data belonging to x3 is output from the binarization circuit 14, the binary data group D1 in FIG.
3), the read control circuit 20 controls the control signal SEL.
<0,1> is output as 1 and SEL2.
The selector 50 outputs the output (that is, OR
The output of the inverted Y * 2 + x3 calculation by the circuit 54 is output from the X terminal. As a result, the theoretical sum of the previous calculation result at x2 (output from the shift register 18) and the value at x3 is input to the shift register 18.

When the binary data belonging to x4 is output from the binarization circuit 14, the binary data group D in FIG.
14), the read control circuit 20 controls the control signal SEL.
<0,0> is output as 1 and SEL2.
The selector 50 is the shift register 18 input to the D terminal.
Is output from the X terminal as it is. As a result, the output from the shift register 18 is obtained as the result of the above-mentioned theoretical operation of inverted Y · x2 + x3, that is, as the value of the read data X determined based on the binary data obtained by the four scans. Is output. Note that this value is held in the shift register 18 and used as the data Y of the previous line when scanning the next line. The reading apparatus of this embodiment repeats the above calculation while driving the motor 22 at 200 pps and obtaining binary data x1, x2, x3, and x4 corresponding to one line by scanning four times.

Next, the theoretical calculation in the case of increasing the rotation speed of the motor 22 to drive the motor 22 at 267 pps shown in FIG. 3 and obtain the read data corresponding to one line by scanning three times will be described. When the binary data belonging to x1 is output from the binarization circuit 14 (included in the binary data group D21 of FIG. 3), the read control circuit 20 controls the control signal SEL1, as in the case of 200 pps described above. SE
<0,0> is output as L2, whereby the selector 50 outputs the output from the shift register 18 input to the D terminal as it is from the X terminal.

Next, when the binary data belonging to x2 is output from the binarization circuit 14, the binary data group D2 in FIG.
2), the read control circuit 20 is the above-mentioned 200 pp
As in the case of s, as the control signals SEL1 and SEL2,
1, 0> is output, whereby the selector 50 outputs the output input to the B terminal (that is, the output that the AND circuit 52 performs the operation of inverted Y · x2) from the X terminal.

Further, when the binary data belonging to x3 is output from the binarization circuit 14, the binary data group D2 in FIG.
3), the read control circuit 20 includes the above-mentioned 200
As in the case of pps, <0, 1> is output as the control signals SEL1 and SEL2, which causes the selector 50 to output C
The output input to the terminal (that is, the output obtained by the operation of inverted Y · x2 + x3 by the OR circuit 54) is output from the X terminal. As a result, the theoretical result of the previous calculation at x2 (output from the shift register 18) and x3 is input to the shift register 18 and determined based on the binary data obtained by three scans. It is output as the value of the read data X.

Next, the processing in the case where the speed of the motor 22 is further improved and the motor 22 is driven at a steady speed of 800 pps shown in FIG. 3 and one scan is performed every time one line is sent will be described. The read control circuit 20 controls the control signals SEL1 and SEL.
<1,1> is output as 2 and the selector 5
0 is the output (that is, the binarization circuit 14
(Binary data output from) is output as it is as read data X from the X terminal. That is, D3 in FIG.
The binary data corresponding to D4 is directly output as the read data of the data calculation circuit 16. In this way, in this embodiment, pixel data (read data) is calculated by calculation during the slew-up period while maintaining the synchronous relationship with the motor 22 while fixing the scanning time.

FIG. 6 and FIG. 7 are diagrams showing the results of a test of how the reading apparatus of this embodiment reads a thin diagonal line of a document in the slew-up period. Figure 6
The diagonal line in FIG. 7 indicates the reading line density of 7.7 lin which is generally used in facsimiles and the like.
This corresponds to a thinness of about 0.1 mm width when e / mm is set.

FIG. 6 shows a case in which read data corresponding to one line is obtained by driving at 200 pps and scanning four times, and FIG. 7 corresponds to one line by driving at 267 pps and scanning three times. The case where read data is obtained is shown. 6A and 7A show lines placed on the original, FIGS. 6B and 7B show binary data of the binarization circuit 14 in each pixel, and FIGS. 6C and 7C show logical operations of each pixel. The result of is shown. That is, in FIG. 6A, for convenience of description, it is considered that the first pixel to the twelfth pixel are arranged side by side on the original from left to right, and the first line on the original from the top to the bottom, 2nd line, 3rd
Lines are lined up, and x1 scanned for the first time, x2 scanned for the second time, x3 scanned for the third time, and x4 scanned for the fourth time are lined up on each line. To be. In the reading apparatus according to the present exemplary embodiment, FIG.
As shown in FIG.
In the scan corresponding to x1 of the third line corresponding to the first pixel, 0 is obtained as binary data, x2 is set to 1, x3 is set to 1, and x4 is set to 1. Then, the first pixel is determined to be 1, that is, black data by the theoretical calculation of the inverted Y · x2 + x3 described above, and is output as shown in FIG. 6C. 7A, 7B, and 7C also show the same processing steps, and thus description thereof will be omitted. By this test, it was proved that the reading apparatus of the present example could read a thin diagonal line on the original without interruption between the reading lines even during the slew-up period.

In this embodiment, the value of X is determined by the theoretical calculation of inverted Y · x2 + x3.
Here, the reason why the values of x1 and x4 are not referred to when performing four scans is to cut off the influence of adjacent lines, and the value of x1 is not referred to immediately before when performing three scans. This is to cut off the influence of the line. That is, x
If a value of 1 is used to determine this read data,
When the previous line (Y) is black, it is easy to determine that the value of X is 1, that is, black, even if part of this black is applied to x1,
This is to avoid such a judgment. Further, inverted Y, that is, the value (Y) of the pixel of the previous line is inverted and used for the theoretical calculation, when the value (Y) of the previous line is black,
This is because it is easy to determine the current line (X) to be white, and the thin line is picked up as much as possible.

As described above, in the reading apparatus of the present embodiment, stable output can be obtained from the image scanner 12 by scanning at a constant speed even during the through-up drive period of the motor 22. Also, 1
Scans four or three times when feeding originals for a line,
Since binary data is obtained and read data for one line is calculated by the above calculation, a good read image can be obtained. Further, in the reading apparatus of the present embodiment, when reading data for one line is obtained by scanning four times or three times, the holding capacity of the shift register 18 is not binary data for four or three scans but 1 Since it is sufficient to hold the binary data for the scan, there is also an advantage that the cost of holding the data can be minimized.

Next, another embodiment of the present invention will be described. In the above-described embodiment, the image scanner 1
One line of read data is obtained by performing the main scanning once, and at the same time the original feed in the sub-scanning direction is set to 4 or 1/3 of the steady speed when the motor is started, and at the same time the main scanning of the image scanner is performed 4 or 3 times. One line of read data was obtained by scanning. On the other hand, in this embodiment, read data for one line is obtained by M (integer) main scans of the image scanner, and when the motor is started, the original is fed in the sub-scanning direction at a constant speed of M / N (M <N)
At the same time, the read data for one line is obtained by N (integer) main scans of the image scanner. For example, when a document is being sent at a constant speed by a motor, read data is generated by two main scans. Then, when the motor is started, the feeding of the document in the sub-scanning direction is set to 2/4 of the steady speed, and at the same time, the read data for one line is obtained by the four main scans of the image scanner, that is, as described above. Similarly, binary data (x1, x2,
x3, x4) and the pixel value is inverted Y · x2
Determined by theoretical calculation of + x3. Then, when the start of the motor is completed, the feeding of the document in the sub-scanning direction is increased to 3/4 of the steady speed, and at the same time, the read data for one line is converted into binary data ( x1, x2, x3), and the pixel value is determined by the theoretical operation of inverted Y · x2 + x3.
After that, the process shifts to the constant speed feeding of the document for generating the read data by the two main scans. The mechanical structure of this embodiment is substantially the same as that of the above-mentioned embodiment, and therefore the description thereof is omitted.

In the above-described embodiment, as a slew-up method, a method of stepwise switching between ¼ and ⅓ of the steady speed to reach high-speed operation (steady speed) is taken as an example. As described above, the reading device of the present invention can also adopt a system in which any one of the speeds is directly switched to the high speed operation. In addition, although the facsimile reading device is described in the present embodiment, the present invention can be suitably applied to other reading devices such as a reading device of a copying machine.

[0036]

As described above, in the reading apparatus of the present invention, it is possible to obtain a read image while keeping the scanning speed of the image scanner constant even during the slew-up period. Further, in the present invention, since the value of the pixel in the slew-up period is determined by the theoretical calculation,
A good read image can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a reading device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration of the arithmetic circuit shown in FIG.

FIG. 3 is a timing chart showing an operation example of the reading apparatus of the present embodiment.

FIG. 4 is a diagram showing a positional relationship of read pixels by the reading device according to the embodiment of the present invention.

FIG. 5 is a diagram showing a positional relationship of read pixels by the reading device according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing how diagonal lines on a document can be read during a slew-up period by the reading device of the present embodiment.

FIG. 7 is an explanatory diagram showing how a diagonal line on a document can be read during a slew-up period by the reading apparatus of the present embodiment.

[Explanation of symbols]

 12 image scanner 14 binarization circuit 16 arithmetic circuit 18 shift register 20 reading control circuit 22 motor

Claims (3)

[Claims] 1. An image scanner for reading data by main-scanning an original, and a motor for sending the original in the sub-scanning direction. The motor sends the original in the sub-scanning direction at a constant speed.
The read data for one line is obtained by M (integer) main scans of the image scanner, and at the same time the original feed by the motor in the sub-scan direction is set to M / N (M <N) at a constant speed, A reading device for obtaining read data for one line by N (integer) main scans of the image scanner, further comprising data holding means for holding read data of pixels in the immediately preceding line in the sub-scanning direction; Is a data calculation means for calculating the data corresponding to one pixel of the current line when the feeding speed of N is 1 / N, and the pixel data of the immediately preceding line held in the data holding means and the image scanner Data calculation means for performing theoretical calculation on the basis of data obtained by N times of main scanning to obtain data corresponding to the one pixel. That reading device. 2. When the read data for one line is obtained by four main scans of the image scanner, the data calculation means sets the read data of the pixel on the immediately preceding line to Y, and the read data for the current line is read four times. The data corresponding to the main scanning is set to x1, x2, x3, and x4 from the upstream side, and the data corresponding to the one pixel is inverted Y.
The reading device according to claim 1, wherein the reading device is operated based on a theoretical formula of x2 + x3. 3. When obtaining read data for one line by three main scans of the image scanner, the data calculation means sets the read data of the pixel of the immediately preceding line to Y, and the read data for the current line is read three times. The data corresponding to the main scanning is x1, x2, and x3 from the upstream side,
The data corresponding to the one pixel is converted to inverted Y × 2
The reading device according to claim 1, wherein the reading device is operated based on a theoretical formula of + x3.