JP2001111785A - Image reader and image reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader of a type reading an image of an original for each part of the image through repetition of movement and stop of an optical unit that enhances the image quality by making joints of parts of the image inconspicuous so as to eliminate a color change appearing in the joints of the color image as well as a black/white image. SOLUTION: The optical unit 3 is returned opposite to the subscanning direction from the stop position and brought into a standby state when the scanning is stopped and a change in the light quantity of a light source 11 caused for the standby period of the optical unit 3 is measured. When the movement is restarted, a correction value for black/white balance is set on the basis of this change amount, and the original image in the scanning after the standby state is read on the basis of the correction value and image data are generated and stored in an image data memory 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus provided in an image forming apparatus such as a copying machine or the like, and more particularly, to an image reading apparatus which intermittently scans a document.

[0002]

2. Description of the Related Art Conventionally, as an image reading device for reading a document image provided in a copying machine or the like, a light source moving type device for performing reading scanning by moving a light source with respect to a stopped document has been provided. I have. Such an image reading device is
Platen glass that serves as a document table, a movable optical unit that reads and scans a document image, a motor that drives the optical unit (such as a stepping motor), and a CCD (Charge Coupled Device) that generates image data from reflected light of the document image
e), and a memory for storing image data. The copying machine main body reads out the image data in the memory and forms an image on a predetermined recording material in the image forming apparatus.

[0003] Among such copying machines, in particular, in a compact type apparatus provided with an image forming apparatus composed of ink jet, an original image is read a little at a time and image data is generated for each part. This is used to form an image. With such a configuration, a memory for storing image data can be reduced in size.

An image reading apparatus provided in this type of copying machine scans a document intermittently while repeatedly moving and stopping the optical unit in the sub-scanning direction. If the moving speed of the optical unit in the sub-scanning direction during the reading scan changes, the process of generating image data becomes complicated. Therefore, in the image reading apparatus of the type described above, the optical unit is temporarily returned to the reverse direction in the sub-scanning direction, the movement of the scanning unit is started from the already scanned area, and the optical unit reaches a position where the scanning should be restarted. In some cases, reading scanning can be restarted at a predetermined moving speed.

That is, as shown in FIG.
When reading and scanning are performed in each of areas b, b to c, c to d, and de to e, the optical unit is first stopped after reading and scanning a to b, and moves to the vicinity of c 'by inertia. After that, it is returned to the position b 'which has already been scanned, and waits at this position. The optical unit starts moving from b ′ and accelerates to a predetermined moving speed when a state where scanning can be performed, for example, when there is a sufficient free space in a memory for storing image data, occurs. Bc
Is read and scanned.

On the other hand, in an image reading apparatus, a shading correction and a black-and-white level based on the light amount of a light source in an optical unit are performed on a CCD which receives reflected light of a document and converts the reflected light into an electric signal before starting scanning. Is set.

However, in the image reading apparatus of the type which performs intermittent reading scanning as described above, the scanning time becomes extremely long, and the light amount changes due to a rise in the temperature of the light source. There is a problem that the setting of the black and white level is not appropriate.

[0008] That is, as shown in FIG.
Immediately after lighting, it starts to rise rapidly, gradually increases with time, and becomes saturated after a considerable time has elapsed. In order to eliminate the influence of such a change in light amount, it is conceivable to start reading scanning after the light source light amount reaches a saturated state.
Then, it takes too much time from the start of copying to the output of the copy. Therefore, conventionally, reading scanning is started after a rapid increase area immediately after lighting.

FIG. 9 shows the light source light quantity at each position of the optical unit. As shown in FIG. 9, the light amount of the light source is
Although it is almost constant during the reading scan, it shows a remarkable increase during the standby time longer than the reading scanning time, and the scanning is performed for each of the areas a to b, b to c, cd, and de to e. The amount of light increases. As a result, if the correction is performed only before the start of scanning, the joints between image blocks having different scanning periods can be visually recognized. In particular, in the case of a color image in which a plurality of color images are superimposed, the color changes at the joints. As a result, the image quality is significantly reduced.

To solve the problem of the seam caused by the change in the light amount of the light source, for example, Japanese Patent Laid-Open No. 6-233 discloses
No. 068 discloses a signal for detecting the amount of reflected light from the image line at the scan resuming position immediately after the stop of scanning and immediately after resuming the scanning, and when the difference between the two reflected light amounts is equal to or more than a predetermined value, a signal indicating the fact. Is transmitted to the image reading apparatus main body side, and the image data stored in the memory is corrected.
Alternatively, a configuration for performing processing such as rereading a document from the beginning is described. It also describes that if correction is possible, the data is automatically rewritten to shading correction data that minimizes the difference.

[0011]

However, in the configuration of the above-mentioned conventional publication, the difference between two reflected light amounts obtained from the image line at the scanning restart position immediately after the scanning is stopped and immediately after the scanning is restarted is equal to or larger than a predetermined value. When the seam is conspicuous, a process of correcting image data stored in the memory or a process of rereading a document from the beginning is performed.

Therefore, when the correction processing of the stored image data is selected and the image formation is continued without re-reading, the image data is read out from the memory on the image forming apparatus immediately after the restart of the scanning, and is sequentially printed. Since the configuration cannot be adopted, it is necessary to wait for the image forming operation while the image data in the memory is subjected to the correction processing, and there is a problem that a copy cannot be provided quickly.

If the image forming apparatus reads out the image data from the memory and forms an image immediately after the restart of the scanning, the correction processing of the image data is not suitable for several lines, and the image in that portion becomes bright. Such a phenomenon occurs. In the case of a black-and-white image, even if the image for several lines becomes bright, it is invisible enough to cause no problem,
As described above, in the case of a color image, the image appears as a change in the color tone instead of the color density, so that the image quality is significantly reduced.

Further, in the configuration of the above-mentioned conventional publication, when the difference between the two reflected light amounts is equal to or more than a predetermined value and the joint is conspicuous, if the correction is possible, the shading correction data is rewritten. There is no description about the case where the light amount has changed to such an extent that the shading correction cannot be rewritten, and in that case, there is no choice but to select rereading of the original.

[0015]

In order to solve the above-mentioned problems, an image reading apparatus according to the present invention comprises: a scanning operation for reading an original image while moving an optical unit in a sub-scanning direction orthogonal to a scanning direction; A scanning operation is performed in an image reading apparatus in which the original image is read for each part by repeating the standby operation in which the movement of the unit is stopped and the original image is not read, and the image data for each part is sequentially generated and stored in the memory. The optical unit movement control means for returning the optical unit to the reverse direction in the sub-scanning direction from the stop position when the optical unit is stopped, and a change in the amount of light of the optical unit occurring during a standby period of the optical unit is measured. Reading control means for controlling reading of a document image in a subsequent scanning operation to generate image data.

According to this, the optical unit movement control means returns to the already scanned position in the sub-scanning direction opposite to the position where the scanning operation of the optical unit is stopped, and makes the read control means wait. A change in the amount of light of the optical unit that occurs while the optical unit is on standby is measured, and reading of a document image in a scanning operation after standby is controlled based on the amount of change. That is, when the reading of the document image is restarted in the scanning operation after the standby, the reading is already performed in consideration of the light amount change, and this is stored in the memory.

Therefore, even if the image forming apparatus reads out the image data from the memory immediately after the restart of the scanning to form the image, the image data is already corrected before being stored in the memory. As in the configuration of the conventional publication, there is no phenomenon that the correction of several lines cannot be made in time, the image of the portion becomes bright, and a high-quality image with no seamlessness in the case of a color image as well as a monochrome image. Can be obtained.

In the above image reading apparatus, the reading control means controls the reading in consideration of the change in the amount of light when reading the original image.

As the light source light amount increases, the area determined to be white becomes wider, while the area determined to be black becomes narrower, so that it becomes impossible to determine black at last. By correcting the white level and the black level accordingly, the read image can be generated as image data with an appropriate black and white balance.

In the above image reading apparatus, the reading control means may be configured to move the optical unit to the reference plate to perform shading correction when the change in light amount exceeds a predetermined value. As a result, even if a large light amount change that cannot be dealt with only by the correction based on the black and white balance occurs, the shading correction is performed again, so that the image formation can be continued without interruption.

In this case, in particular, a reference plate used for shading correction is provided at least on the starting end side and the end end side in the moving direction of the optical unit, and the reading control means sets the reference plate close to the standby position of the optical unit. By using the configuration to perform shading correction, the time required for shading correction performed in the middle of reading scan (time required for the optical unit to move to a position where the reference plate can be read)
Is shortened, image formation is completed earlier, and a copy can be provided quickly.

In order to solve the above-mentioned problems, the original reading method of the present invention includes a scanning operation for reading an original image while moving the optical unit in a sub-scanning direction orthogonal to the scanning direction, and a movement of the optical unit. In the image reading method in which the original image is read for each part by repeating the standby operation in which the original image is not read and the operation is stopped, and the image data for each part is sequentially generated, the optical unit is moved from the stop position together with the stop of the scanning operation. Return to the sub-scanning direction in the reverse direction, wait for standby, measure the change in light amount of the optical unit during this standby period, and read the original image in the scanning operation after standby taking into account the change in light amount. It is characterized by.

According to this, the optical unit is returned to the already-scanned position in the sub-scanning direction opposite to the position where the scanning operation of the optical unit is stopped, and is made to stand by. The reading of the original image in the scanning operation after the standby is controlled based on the amount of change in the optical unit, and the reading of the original image in the scanning operation after the standby is restarted. The reading takes into account the change, and this is stored in the memory.

Therefore, even if the image forming apparatus reads out the image data from the memory and forms an image immediately after the restart of the scanning, the image data is already corrected before being stored in the memory. As in the configuration of the conventional publication, there is no phenomenon that the correction for several lines cannot be made in time and the image of the portion becomes bright, and a high-quality image without a seamless color image as well as a monochrome image. Can be obtained.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described below with reference to FIGS.

An image reading apparatus according to an embodiment of the present invention is provided for an image forming apparatus such as a copying machine or a facsimile machine.

First, the configuration of the image reading apparatus will be described. As shown in FIG. 1, the image reading apparatus mainly includes a platen glass 1, first and second shading / black and white balance plates (hereinafter, referred to as correction plates) 2a and 2b, an optical unit 3, and an optical lens. 4. CCD (Charge Coupled)
Device 5).

The platen glass 1 is a document placing table on which a document G whose image is to be read by the image reading apparatus is placed, and is made of a transparent glass or the like. First and second correction plates 2a and 2
Reference numeral b denotes a reference plate used for shading correction and setting of a black-and-white level. The first correction plate 2a is provided on the starting end side of the platen glass 1 in the sub-scanning direction (the moving direction of the optical unit 3). Are provided on the end end side. The area where the first and second correction plates 2a and 2b are arranged is outside the original image reading area.

The optical unit 3 includes a light source 11 composed of, for example, a rod-shaped halogen lamp and an elliptical reflector, and the light source 11.
Guiding the reflected light of the emitted light to the optical lens 4;
It has first to third reflection mirrors 12 to 14. The light source 11 and the first reflection mirror 12 constitute a first scanning unit, and the second and third reflection mirrors 13 and 14 constitute a second scanning unit.
Are configured.

As shown in FIGS. 2A to 2D, the optical unit 3 moves along the platen glass 1 into first and second optical units.
Are individually moved from the left (starting end) to the right (end end) in the figure to expose the original G,
The reflected light is guided to the optical lens 4.

The optical lens 4 forms an image of the reflected light from the third reflection mirror 14 on the CCD 5. CC
D5 converts the light imaged by the optical lens 4 into an electric signal.

The analog electric signal obtained by the CCD 5 is converted into digital image data and then stored in an image data memory 16 provided in the image reading apparatus. The image data stored in the image data memory 16 is sequentially read out by the image processing unit 15 provided on the image forming apparatus side, subjected to predetermined image processing, and then printed out using the image forming apparatus. After that, the image data memory 1
6 is deleted.

Although the image data memory 16 is provided in the image reading apparatus and the image processing section 15 is provided in the image forming apparatus main body on which the image reading apparatus is mounted, the image processing apparatus has been described. The configuration of the unit 15 and the image data memory 16 on the image forming apparatus main body side or vice versa may be considered.

The reading of the original image by the image reading apparatus is performed by controlling the above-described functional parts by a control unit (not shown).

Next, the image reading operation of the image reading apparatus will be described with reference to the flowchart of FIG. FIG. 3 is a flowchart showing a flow of the operation of the image reading apparatus.

The original G is placed on the platen glass 1,
When a reading start instruction is input from the user, the control unit first irradiates the light of the light source 11 in the optical unit 3 to the first correction plate 2a on the starting end side to perform initial correction (S1). The initial correction performed in S1 includes shading correction using the first correction plate 2a, setting of a black and white level,
And other gain adjustments.

Here, the setting of the black and white level will be described. As shown in FIG. 4, in the present image reading apparatus, the reflected light is recognized by being divided into 8 bits (0 to 255 gradations). Then, by shading correction, 0
The amount of light corresponding to the first and 255th gradations is set, and the white level W1 and the black level B1 are set within the 255 gradations by setting the black and white level.

The white level W1 is the maximum amount of reflected light of a white original obtained in reading scanning, and the black level B1 is the minimum amount of reflected light of a black original. That is, in the present image reading apparatus, the image data of the document G enters between the white level W1 and the black level B1 obtained as the reflected light from the first correction plate 2a.

In the initial correction of S1, the pixels having the maximum light amount and the pixels having the minimum light amount obtained by irradiating the first correction plate 2a with light are detected, and the light amount of the pixel having the maximum light amount is determined by the white level W1 and the minimum light amount. The light amount of the light amount pixel is set as the black level B1. At that time, between the 0th gradation and the white level W1,
A margin is provided between the gray level 255 and the black level B1.

After the initial correction in S1, the control unit starts moving the optical unit 3 in the sub-scanning direction, starts reading scanning of the original image, and sets the monochrome level W1 set in S1.
Generate image data in B1 and sequentially store it in memory. In the meantime, it is checked whether all the scans in the sub-scanning direction have been completed or the image data memory 16 is not full (S2).
~ S4). Then, in S4, the image data memory 1
When the control unit 6 detects that the full state has been reached, the control unit stops reading and scanning of the original image and returns the optical unit 3 to a predetermined standby position (S5).

The stand-by position is a position at which the reading is interrupted this time, and is returned by a predetermined distance in consideration of the speed rise of the optical unit 3 in a direction opposite to the sub-scanning direction from the reading scanning restart position to be read next. It is. In this image reading apparatus, the moving speed in the sub-scanning direction during scanning is made constant by securing the distance from the standby position to the scanning restart position as the approach path of the optical unit 3.

Then, the control section performs black and white balance correction at this standby position. That is, first, at the standby position, the original G is irradiated with light from the light source 11 of the optical unit 3, a bright portion is detected in the main scanning direction of a certain line of the original G, and the reflected light amount of the portion is detected. Measurement is performed, and the reflected light amount is stored in the memory of the control unit (S6; first light amount measurement). Thereafter, the data is deleted by the image forming apparatus having the image reading apparatus, and the image data is stored in the image data memory 16.
(S7), and waits until the image data memory 16
Is detected, and when the scanning can be resumed, the control unit performs the second light quantity measurement (second light quantity measurement) at the standby position, similarly to S6 (S8). . At this time, the line of the original G to be read is
This is the same as the line read in S6.

In S8, when the second light quantity measurement is completed, a difference from the light quantity obtained in S6, which is stored in the memory of the control unit, is calculated to obtain a correction value, and based on the correction value, First, it is determined whether correction of the black and white balance is necessary (S9).

Here, when it is determined that the light amount difference is an allowable value and no correction is necessary, the process returns to S2, and reading scanning is started from the next original line.

On the other hand, when it is determined in S9 that the correction of the black and white balance is necessary, it is determined whether or not the correction value is usable (S10). Move to S12.

Here, the case where the correction value of the black-and-white balance cannot be used means that, as shown in FIG. 4, the overall light quantity shifts upward as the light quantity of the light source 11 increases, and is actually obtained. This is the case where the light amount becomes extremely close to the black level B1 and the number of pixels determined to be black becomes extremely small, or the actually obtained light amount far exceeds the white level W1 and the margin with the white level W1. Is too wide, and the number of items determined to be white becomes extremely large.

In S10, where it is determined that the correction value can be used, in S11, the black and white balance is corrected as follows.

That is, for example, when the optical unit 3 is stopped for the nth time, if correction is required in S10, the image data obtained in S6 is D6n, and the image data obtained in S8 is D8n.
Assuming that the image data obtained from the initial correction value of S1 is Gn, Dn + 1 which is the image data after resumption after the nth stop is Dn + 1 = (D6n / D8n) × Gn, and the light amount increases. It is possible to correct the black and white balance after a change in the amount of light by lowering the light amount. (D6n
/ D8n) is a correction value of the black and white balance.

However, in such a correction, S6, S
If all the image data detected in step 8 is dark, it is desirable to avoid the correction.
After the scanning is stopped, when returning to the standby position, the image line returns to the image line having the bright data, and the image data in S6 and S8 is detected again to avoid that all the image data comes from a dark area. .

In addition, the data of S6 and S8 may be obtained by increasing the sensitivity of the CCD 5 by, for example, increasing the exposure time of the CCD 5 only during the measurement of S6 and S8. When the original cover (not shown in FIG. 1) covering the upper portion of the platen glass 1 is white and the original G is smaller than the platen glass 1, the image data of S6 and S8 is obtained from the original cover to obtain a white level. You may.

As described above, when the optical unit 3 stops in a dark portion of the document G and correction is impossible, it is necessary to stop the movement of the optical unit 3 for correction. After the optical unit 3 reads the original G,
The distance to stop and return in the normal reading process is shown in FIG.
, The data of the line of the original G returned by a distance between bb 'from the position at the time of reading is stored in memory, and a scan stop for correction occurs. In this case, by returning the optical unit 3 from the stop position by a distance of bb ', the data obtained in S8 can be compared with the stored data to perform correction. At this time, D6
Naturally, the image data at the position b 'stored in place of n is used as comparison data.

When the setting of the correction value in S11 is completed, the control unit returns to S2 and starts reading scanning with the corrected black and white balance from the next line.

On the other hand, in S12, when it is determined in S10 that the black and white balance cannot be corrected, the re-initialization process shown in the flowchart of FIG. 5 is performed, and the shading correction and the setting of the black and white level are performed again.

That is, as shown in FIG. 5, the control unit first determines whether or not the standby position of the optical unit 3 has exceeded the intermediate point (center) of the platen glass 1 in the sub-scanning direction (S21). When it is determined that the intermediate point has been exceeded, the optical unit 3 is moved to the end end side of the platen glass 1 and
The initial correction is performed again using the second reference plate 2b provided on the end end side (S23, S24).

On the other hand, if the standby position has not reached the intermediate point of the platen glass 1, the control unit returns the optical unit 3 to the starting end side of the platen glass 1 and the first correction plate 2a located on the starting end side. To execute the initial correction again (S2
2, S24).

By this reinitialization, as shown in FIG. 4, the light amount allocated to the 8 bits is changed from 0 to 255 to 0 'to 255' corresponding to the increase in the light amount of the light source 11, and the black and white level is changed. It is reset to B2 and W2,
Reading scanning can be resumed.

As described above, the present image reading apparatus returns the optical unit 3 from the stop position in the sub-scanning direction in the opposite direction with the stop of the scanning operation, and makes the optical unit 3 stand by. Is measured, and the monochrome data of the image data of the document G in the scanning operation after the standby is corrected and read based on the amount of change. Therefore, when the reading of the original image is restarted in the scanning operation after the standby, the image data is already in the image data memory 16 in consideration of the change in the light amount, and is stored in the image data memory 16.

Thus, even if the image forming apparatus reads out image data from the image data memory 16 and forms an image immediately after the restart of scanning, the image data is already corrected before being stored in the image data memory 16. Since it is performed, not only a monochrome image but also a color image can be obtained without a seamless high-quality image.

FIG. 6 is a graph showing the relationship between the position of the optical unit of the image reading apparatus and the amount of light. In the image reading apparatus of the type that performs correction based on the change in the amount of light at the position where the reading scan is stopped, in this figure, after scanning from the point ○ to the point ●, returns to the point △, and starts the optical unit 3 at the point ▲. When the point reaches the point (scan restart position), the correction value of the black and white balance is reset based on the light amount difference between the point and the point. Therefore, before the resetting of the correction value is completed, the reflected light from the vicinity of the point ○ is received.
The image data for the first few lines cannot be completely corrected, and a color seam occurs.

On the other hand, in this image reading apparatus, the light amount difference between the point （(at the start of standby) and the point ▲ (at the end of standby) is detected, and based on this, a correction value of the black and white balance is set. ○ The light quantity at the point is read. Therefore, the image data after the restart of scanning is generated using the new correction value and stored, so that a seamless image can be formed.

In this image reading apparatus, the light source 1
If it is determined that the change in the amount of light exceeds the predetermined value and the correction value cannot be used, the optical unit 3 is moved to the reference plate 2a or 2b to perform the shading correction. Even if the light amount changes, image formation can be continued without interruption.

In particular, in the present image reading apparatus, reference plates 2a and 2b used for shading correction are provided at the start end side and the end end side in the moving direction of the optical unit 3, and are close to the standby position of the optical unit 3. Since the shading correction is performed using one of the reference plates, the time required for performing the shading correction again during the scanning (eg, the time required for the optical unit to move to a position where the reference plate can be read) is reduced, and the image can be read more quickly. Upon completion of formation, copies can be provided quickly.

In the present embodiment, S shown in FIG.
In 7, the scanning is set to restart when the image data memory 16 becomes empty, but the operation of the image reading apparatus is not limited to this. For example, the reading scan may be restarted when a sufficient free area is generated in the image data memory 16.

[0064]

As described above, according to the image reading apparatus of the present invention, the optical unit movement control means for causing the optical unit to return to the reverse direction in the sub-scanning direction from the stop position and stand by when the scanning operation is stopped, A reading control unit that measures a change in the amount of light of the optical unit that occurs during the period, and controls reading of a document image in a scanning operation after standby based on the change amount.

Further, as described above, according to the original reading method of the present invention, when the scanning operation is stopped, the optical unit is returned from the stop position in the sub-scanning direction in the opposite direction to stand by, and the optical unit generated during this standby period is stopped. Measure the light intensity change,
In the scanning operation after the standby, the original image is read in consideration of the change in the light amount.

Thus, when the reading of the original document is restarted in the scanning operation after the standby, the reading is already performed in consideration of the change in the light amount, and this is stored in the memory. Even when the image data is read from the memory on the device side to form the image, the image data is already corrected before being stored in the memory.

As a result, unlike the configuration of the above-mentioned conventional publication, the correction for several lines cannot be made in time, and there is no phenomenon that the image in that portion becomes bright. There is an effect that a seamless high-quality image can be obtained.

In the image reading apparatus of the present invention,
One example of the reading control unit that controls reading in consideration of a change in light amount when reading a document image is correction of black and white balance.

When the amount of light from the light source increases, the area determined to be white increases while the area determined to be black narrows, and finally the determination of black becomes impossible. There is an effect that image data can be generated with an appropriate black and white balance.

Also, in the image reading apparatus of the present invention,
When the change in the light amount exceeds a predetermined value, the reading control unit may move the optical unit to the reference plate to perform shading correction.

Even if a large light amount change that cannot be dealt with only by the correction based on the black-and-white balance occurs, the shading correction is performed again, so that there is an effect that the image formation can be continued without interruption.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a schematic diagram illustrating a configuration of an image reading apparatus.

FIGS. 2A to 2D are explanatory views showing the movement of an optical unit in the image reading apparatus of FIG. 1;

FIG. 3 is a flowchart illustrating a procedure of a document image reading operation in the image reading apparatus of FIG. 1;

FIG. 4 is an explanatory diagram showing a state where it is necessary to change shading correction data and reset a black-and-white level in accordance with a change in light source light amount in the image reading apparatus of FIG.

FIG. 5 is a flowchart showing a procedure of a reinitialization correction process in the flowchart of FIG. 3;

FIG. 6 is an explanatory diagram showing a relationship between start / stop of an optical unit and an irradiation light amount in the image reading apparatus of FIG. 1;

FIG. 7 is an explanatory diagram illustrating a relationship between a lapse of time after the start of movement in the sub-scanning direction and a movement speed of the optical unit in the image reading apparatus.

FIG. 8 is an explanatory diagram showing a relationship between a lighting time of a light source provided in an optical unit of the image reading apparatus and a light amount.

FIG. 9 is an explanatory diagram showing a relationship between a position in a sub-scanning direction and a light amount of a light source provided in an optical unit of the image reading apparatus.

[Explanation of symbols]

 Reference Signs List 1 platen glass 2a first reference plate (reference plate) 2b second reference plate (reference plate) 3 optical unit 4 optical lens 5 CCD 11 light source 16 image data memory (memory)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 1/401 G06F 15/64 400D H04N 1/40 101A (72) Inventor Yoshihiro Mizuguchi 22nd Nagaikecho, Abeno-ku, Osaka-shi, Osaka No. 22 F-term in Sharp Corporation (reference) 2H108 AA01 CB01 FA02 FA17 FA29 FA34 GA01 GA11 2H110 AA01 AA16 AA22 AC14 BA13 CD02 5B047 AA01 AB01 AB04 BA02 BB02 BC15 CA08 CA17 CB09 CB23 DA04 DC01 DC07 5C072 LA12BA08 MB01 MB05 MB06 RA06 RA16 UA03 UA11 XA01 5C077 LL19 MM27 MP08 PP06 PP44 PP45 PP58 PQ12 PQ22 SS01 TT06

Claims (5)

[Claims] A scanning operation for reading a document image while moving an optical unit in a sub-scanning direction orthogonal to a scanning direction, and a standby operation for stopping the movement of the optical unit and not reading a document image are repeated. In an image reading apparatus that reads an image for each part, sequentially generates image data for each part, and stores the image data in a memory, an optical unit that stops the scanning operation and returns the optical unit from the stop position to the reverse direction in the sub-scanning direction and waits. Movement control means, and reading control means for measuring a change in the light amount of the optical unit occurring during a standby period of the optical unit, and controlling reading of a document image in a scanning operation after the standby to generate image data based on the change amount An image reading apparatus comprising: 2. The image reading apparatus according to claim 1, wherein said reading control means corrects a black-and-white balance when reading an original image. 3. The reading control device according to claim 1, wherein the reading control means moves the optical unit to a reference plate to perform shading correction when the light amount change exceeds a predetermined value. Image reading device. 4. A reference plate used for shading correction is provided at least on a start end side and an end end side in a moving direction of the optical unit, and the reading control means determines that the light amount change exceeds a predetermined value. 2. The method according to claim 1, wherein the shading correction is performed using a reference plate near the standby position of the optical unit.
Or the image reading device according to 2. 5. The method according to claim 1, wherein a scanning operation for reading the original image while moving the optical unit in a sub-scanning direction orthogonal to the scanning direction and a standby operation for stopping the movement of the optical unit and not reading the original image are repeated. In an image reading method for reading an image for each part and sequentially generating image data for each part, the optical unit is returned from the stop position in the sub-scanning direction in a reverse direction with the stop of the scanning operation, and the standby is performed. An image reading method comprising: measuring a change in the amount of light of an optical unit that occurs; and reading a document image in the scanning operation after standby in consideration of the change in the amount of light.