JP2003037715A - Image reader, control method therefor and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that can reduce the occurrence of image slippage and enhance the performance of reading. SOLUTION: The image reader senses an edge of a first side of an original in the main scanning direction, on the basis of an output of a CCD 209 for each reading of originals and respectively revises an output timing of a main scanning synchronization signal SYNC- CCD of the CCD 209 and an output timing of a main scanning synchronization signal SYNC- CS of a read sensor being a contact sensor for to updating each output timing of each main scanning synchronization signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image including first reading means for reading image information on a first side of an original and second reading means for reading image information on a second side of the original. The present invention relates to a reader, a control method thereof, and a program.

[0002]

2. Description of the Related Art Conventionally, as an image reading apparatus for reading a double-sided original, there is an image reading apparatus equipped with an automatic original feeder (hereinafter referred to as ADF) having an original reversing mechanism. When reading a double-sided original with this image reading apparatus, first, the ADF
The original is fed from the original, the image on the front side of the original is read, and after the reading of the image on the front is completed, the original is inverted by the original inversion mechanism of the ADF to be fed and the image on the back of the original is read.

However, in the image reading apparatus having the above configuration, A
Due to the DF, the time to reverse the original becomes dead time,
In addition to lowering the throughput, document reversal may damage the document.

In view of this problem, in recent years, a reading system is provided in the ADF, and the reading system in the ADF is used to read the front side image and the back side image by one-time document feeding operation. Readers have been proposed.

An image reading apparatus capable of 1-pass double-sided image reading will be described with reference to FIGS. 6 and 7. Figure 6
FIG. 7 is a schematic configuration diagram of an image reading apparatus capable of single-pass double-sided reading, and FIG. 7 is a top view showing a document placing table 71 of the ADF 70 in FIG.

This image reading apparatus, as shown in FIG.
AD having a document table 71 on which a plurality of documents can be stacked
An F70 and a reading unit 200 that reads an image on the front surface of the document conveyed by the ADF 70 are provided.

As shown in FIG. 7, an original is placed on the original placing table 71 of the ADF 70 such that the original is sandwiched by the original guides 31. The document guide 31 is movable in the direction indicated by the arrow in the figure, and a size sensor (not shown) generates a signal in conjunction with the movement of the document guide 31. The signal of the size sensor allows the ADF 70 to detect the size of the document placed on the document table 71. The ADF 70 and the image reading device are connected to each other via an interface (not shown) for transmitting and receiving the status of each other, and the document placed on the document table 71 on the image reading device side is also connected via this interface. Can know the size of.

The ADF 70 separates a plurality of originals placed on the original placing table 71 one by one by the separating rollers 72 and 73, and guides the separated originals in accordance with the rotation of the conveying roller 75 in the arrow direction. It is conveyed to the reading position along 74 and 77.

The reading unit 200 moves immediately below the shading correction plate 211 until the original is conveyed to the reading position, and reads the shading correction plate 211 to obtain shading correction data. When the acquisition of the shading correction data is completed, the reading unit 200
Moves to just below the flow reading window 212, and is in a reading standby state until a document is conveyed.

When the original is conveyed to the position of the flow reading window 212, the surface image of the original is read by the reading unit 200. Specifically, the original image illuminated by the lamp 201 in the reading unit 200 includes a first mirror 205, a second mirror 206, a third mirror 207, and a lens 208.
An image is formed on the CCD 209 via the, and is read by the CCD 209 line by line in the main scanning direction. Then, the document is transported by the transport roller 75 at a predetermined speed, and the image on the document surface is sequentially read in the sub-scanning direction.

As the image on the front side of the original document is conveyed, the end of the original document is conveyed to the position just below the same size reading box 250, and the image on the back side of the original document is read by the same size reading box 250. The optical system of the same size reading box 250 is
It is composed of a SELFOC lens 251, a contact sensor 252, and a lamp 253. An image on the back surface of the document illuminated by the lamp 253 is formed on the contact sensor 252 via the SELFOC lens 251. The image formed on the contact sensor 252 is an image in units of lines of the same size. Then, the document is transported by the transport roller 75 at a predetermined speed, and the image on the back surface of the document is sequentially read in the sub-scanning direction.

The originals whose both sides have been read are sequentially discharged to the discharge tray 78.

The image data of the front surface and the back surface thus read are sent to an image processing circuit (not shown) and subjected to a predetermined image processing, and then a host computer connected to the image reading apparatus or It is output to a printer or the like.

On the other hand, when reading a book-type document such as a spread book, the ADF 70 is opened and the document glass 20 is opened.
3 is placed on the reading unit 200 and the second mirror 20.
6, the third mirror 207 is scanned rightward in FIG. 6 to read the image of the original.

In such an image reading apparatus, registration adjustment of the read image is required. That is, since there is some variation in the assembly accuracy of the optical system, it is necessary to adjust, for each machine, from which pixel of the CCD 209 in FIG. 6 the reading start position of the original image. I have to. If this adjustment is not appropriate,
The image is misaligned, causing unnecessary margins, or the image is missing.

This resist adjustment also needs to be performed in the same size reading box 250, of course. For the resist adjustment, for example, as described in Japanese Patent Application Laid-Open No. 2000-151910, a system that reads a black line in a specific chart using a specific chart and performs the resist adjustment according to the read position information of the read black line. Is proposed.

Further, Japanese Patent Laid-Open No. 5-328052 discloses a method of performing resist adjustment in both the platen mode and the ADF mode using a black original. In the example of FIG. 6, the platen mode is used for adjusting the registration of the reading system of the reading unit 200, and the ADF mode is the same-size reading box 25.
This corresponds to the registration adjustment of the reading system of 0.

[0018]

Even if the registration adjustment is performed, the registration may be misaligned for each document. For example, in the ADF 70 and the reading unit 200, rough registration adjustment may be performed in advance. Further, the document width set by the document guide 31 may be strictly set to be slightly wider than the actual document width so that the document can be conveyed smoothly. Further, even if the document to be placed has a uniform A4 size, the size may be slightly different.

An object of the present invention is to provide an image reading apparatus capable of reducing the image shift and improving the reading performance, a control method thereof, and a program.

[0020]

The invention according to claim 1 is
The first reading means for reading the image information on the first side of the original and the second reading means for reading the image information on the second side of the original are provided, and are read by the first reading means. An image reading apparatus which outputs image information and outputs the image information read by the second reading means, wherein an edge portion on the first surface of the document is output based on the output of the first reading means. Edge detecting means for detecting, a range of effective image data of image information output from the first reading means based on a detection result of the edge detecting means, and an effective image of image information output from the second reading means. And a changing means for changing the range of data.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the first reading means and the second reading means are line image sensors for reading image information line by line. The main scanning synchronization signal synchronized with the first line image information on the first surface of the original is output as the main scanning synchronization signal of the first reading unit, and the original is used as the main scanning synchronization signal of the second reading unit. Second
The main scanning synchronizing signal is output in synchronization with the first line image information on the plane.

According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, the changing means determines the output timing of the main scanning synchronization signal of the first reading means based on the detection result of the edge detecting means. The output timing of the main scanning synchronization signal of the second reading means is changed.

According to a fourth aspect of the present invention, in the image reading apparatus according to the second aspect, the changing means changes the main scanning synchronizing signal of the first reading means to the effective image data based on the detection result of the edge detecting means. And the period from the main scanning synchronizing signal of the second reading means to the effective image data are changed.

The invention according to claim 5 is the invention according to claims 1 to 4.
The image reading apparatus according to any one of the items 1 to 3, further comprising a document feeding unit that feeds documents one by one, and the second reading unit is provided in the automatic document feeding device. It is arranged at a downstream side position in the sub scanning direction with respect to the reading sensor.

The invention according to claim 6 is the invention according to claims 1 to 5.
In the image reading device described in any one of the above items, when the edge detection unit cannot detect an edge,
The changing means is prohibited from changing the range of the effective image data of each image information.

The invention according to claim 7 is the invention according to claims 1 to 5.
In the image reading apparatus described in any one of the above 1, the edge detecting unit detects the edge portion and the changing unit changes the range of the effective image data of each image information every time the document is read. It is characterized by further comprising control means.

The invention according to claim 8 is the invention according to claims 1 to 7.
The image reading device described in any one of the above 1 to 3 and further includes an output unit that outputs the effective image data.

According to a ninth aspect of the present invention, there is provided first reading means for reading the image information on the first side of the original, and second reading means for reading the image information on the second side of the original. ,
A method of controlling an image reading apparatus, which outputs the image information read by the first reading unit and outputs the image information read by the second reading unit, wherein the first reading unit outputs the image information. An edge detecting step of detecting an edge portion on the first surface of the original based on the detection result, and a range of effective image data of image information output from the first reading means based on the detection result of the edge detecting step and the first range. And a change step for changing the range of the effective image data of the image information output from the second reading means.

According to a tenth aspect of the present invention, in the control method of the image reading apparatus according to the ninth aspect, the first reading unit and the second reading unit are line image sensors that read image information line by line. The main scanning synchronization signal of the second reading sensor is output as the main scanning synchronization signal of the first reading sensor, and the main scanning synchronization signal synchronized with the first line image information on the first surface of the document is output. The main scanning synchronizing signal is output in synchronization with the first line image information on the second surface of the document.

According to an eleventh aspect of the present invention, in the control method of the image reading apparatus according to the tenth aspect, in the changing step, the main scanning synchronization signal of the first reading means is based on the detection result of the edge detection process. Output timing and the second
And changing the output timing of the main scanning synchronization signal of the reading means.

According to a twelfth aspect of the present invention, in the control method of the image reading apparatus according to the tenth aspect, the first step is performed based on the detection result of the edge detecting step in the changing step.
The period from the main scanning synchronizing signal of the reading means to the effective image data and the period from the main scanning synchronizing signal of the second reading means to the effective image data are changed.

According to a thirteenth aspect of the present invention, in the method of controlling the image reading apparatus according to any one of the ninth to twelfth aspects, the image reading apparatus further includes a document feeding unit for feeding the documents one by one. However, the second reading means is provided in the automatic document feeder and is arranged at a position downstream of the first reading means in the sub-scanning direction.

According to a fourteenth aspect of the present invention, in the image reading apparatus control method according to any one of the ninth to twelfth aspects, when an edge cannot be detected in the edge detecting step, in the changing step, It is characterized in that the change of the effective image data range of each of the first and second image information is prohibited.

According to a fifteenth aspect of the present invention, in the image reading apparatus control method according to any one of the ninth to fourteenth aspects, the edge detecting step and the changing step are executed every time the original is read. It is characterized by further comprising a step of controlling so as to update the range of the effective image data of each image information.

According to a sixteenth aspect of the present invention, in the image reading apparatus control method according to any one of the ninth to fifteenth aspects, the method further comprises an output step of outputting the effective image data.

According to a seventeenth aspect of the present invention, there is provided first reading means for reading the image information on the first side of the document, and second reading means for reading the image information on the second side of the document. An image reading device that outputs the image information read by the first reading unit and outputs the image information read by the second reading unit, based on the output of the first reading unit. An edge detecting unit that detects an edge portion on the first surface, a range of effective image data of image information output from the first reading unit based on a detection result of the edge detecting unit, and the second reading unit. It functions as a changing unit that changes the range of the effective image data of the output image information.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic enlarged view showing the periphery of a conveying roller in an image reading apparatus according to an embodiment of the present invention, and FIG. 2 is a relative positional relationship between a document and a CCD and reading by the CCD. It is a figure which shows each pixel data. Here, in the figure, the same members as those in FIG. 6 are designated by the same reference numerals. Further, FIG. 1 shows a document feeding state in which the leading edge of the document is read by the CCD 209 (CCD 209 in FIG. 6).

The document conveying roller 75 is colored with a density according to a predetermined density standard. Since the background color of the original 40 is usually white in many cases, the data of the front end of the original read by each pixel of the CCD 209 (not shown) is as shown in FIG.
The data is a mixture of black data (represented by "■") and white data (represented by "□"). As can be seen from the reading state of the CCD 209 in FIG. 2, it is easy to detect that the edge portion (edge portion) of the document is at the position of the pixel A and the pixel A ′ by image data processing such as general edge enhancement. Is feasible. If the document is, for example, an A3 document, the number of pixels between pixel A and pixel A ′ is the number of pixels corresponding to the short side of 297 mm of the A3 document, but even if the document size is the same A3 size, for example, for each manufacturer. They are subtly different, and in some cases, even the same manufacturer may differ depending on the lot.

Here, the position of the pixel A (corresponding to the position of the edge portion) is the effective image start position of the front surface image in the CCD 209, and the position of the pixel A'is the back surface of the contact sensor 252 (shown in FIG. 6). This is the effective image start position of the image.

The relative positional relationship between the CCD 209 and the contact sensor 252 is, of course, different for each machine, but once the ADF 70 is incorporated in the image reading apparatus and mounted, the relative positional relationship is fixed. This relative positional relationship will be described with reference to FIG. FIG. 3 is a diagram showing a relative positional relationship among the document 40, the CCD 209, and the contact sensor 252.

When the ADF 70 is built in and attached to the image reading apparatus, as shown in FIG.
The relative amount of deviation between the last pixel and the leading edge pixel of the contact sensor 252 is determined (described as n pixels in this figure). For example, the resolution as a reading device is 600dp
i, maximum document size is A3, A3 short side 297m
Since 7016 pixels are required as the minimum number of pixels to read m, in this case, the CCD 209 and the contact sensor 252 have an effective total number of 7500 pixels.
The pixels of the front and rear pixels are provided.

Therefore, CC by mounting the ADF 70
The relative pixel shift amount n between the D209 and the contact sensor 252 is (7500-7016) / 2 = 2 at maximum.
It is designed to have 42 pixels or less, and is configured to read images on both sides.

As for the pixel shift amount n, after the ADF 70 is attached, the output states of the CCD 209 and the contact sensor 252 are measured, and the value of the pixel shift amount n is written in a non-volatile backup element (not shown), for example, EEPROM. , This backup value is read every time the power of the device is turned on.

Here, the relative pixel shift amount n after the ADF 70 is attached is 150 pixels, and the pixel A in FIG. 3 is the CCD.
If it is the 90th pixel of 209, it is originally A3 short side 2
Since 97 mm corresponds to 7016 pixels, the pixel A ′ should be 90 + 7016 = 7106 pixels, but it is assumed that the pixel A ′ is the 7086th pixel due to variations in document size.

Since the effective number of pixels of the CCD 209 and the contact sensor 252 is 7500 pixels, the position of the pixel X is before the leading edge of the document reaches the contact sensor 252.
The simple calculation of (7500-7086) -150 = 264 shows that it is the 264th pixel, and X '
Since it is also clear that = 264 + (7086-90) = 7260, it can be seen that the effective pixel range of the contact sensor 252 is from the 264th pixel to the 7260th pixel. Therefore, it is not necessary to detect the position of the leading edge of the document by the contact sensor 252 again.

In this way, when the edge of the document 40 is detected by the state of the CCD 209 reading the document leading edge,
The output timings of the main scanning synchronization signal HSYNC_CCD of the CCD 209 and the main scanning synchronization signal HSYNC_CS of the contact sensor 252 are changed. This change will be described with reference to FIGS. 4 and 5. Figure 4 shows the main scan sync signal for the CCD read state when an edge is detected.
FIG. 5 is a timing chart showing the output timings of HSYNC_CCD and HSYNC_CS, and FIG. 5 is a timing chart showing an example of updating the output timings of the main scanning synchronization signals HSYNC_CCD and HSYNC_CS in accordance with changes in the edge detection state.

When the edge of the document 40 is detected by the state of the leading edge of the document read by the CCD 209, the main scanning synchronization signal HSYNC_CCD (see FIG. 4A) of the CCD 209 and the main of the contact sensor 252 are detected as shown in FIG. The output timing of the scanning synchronization signal HSYNC_CS (see FIG. 4B) is changed, and the main scanning synchronization signal HSYNC_CCD and the main scanning synchronization signal HSYNC_CS are connected to the image reading apparatus, such as an external device such as a host computer or a printer. It is output together with the image data read in.

The external device which has received the main scanning synchronization signals HSYNC_CCD, HSYNC_CS and the image data of the CCD 209 and the contact sensor 252 is operated by the main scanning synchronization signal.
The subsequent image data is recognized as valid image data at the rising timing of HSYNC_CCD or HSYNC_CS, and the image is reproduced according to the valid image data.

When the reading of the first original is completed and the second original is fed, the second original is read in the same manner as described above. Here, when the reading state of the second original is in the state as shown in FIG. 5, the output timing of the main scanning synchronization signal HSYNC_CCD, which was synchronized with the timing of the pixel A, is changed to the timing of the pixel B (see FIG. 5). (See (a)), and changes the output timing of the main scanning synchronization signal HSYNC_CS, which has been synchronized with the pixel X, to the timing of the pixel Y (see FIG. 5B),
The main scanning synchronization signals HSYNC_CCD and HSYNC_CS are sent to an external device.

Although the originals of the same size are fed in this manner, a shift between pixels A and B occurs at the reading position on the CCD 209, and pixels X to X at the reading position on the contact sensor 252. Pixel Y
Even if a gap occurs, it is possible to always send image data having no image shift to an external device.

As described above, in the present embodiment, the edge portion of the original read every time the original is read and the registration information is updated every time the edge is detected, the original guide of the original placing table 71 is read. Image shifts due to subtle differences in settings and document sizes can be eliminated. Further, although it is necessary to perform the above-mentioned registration adjustment for each of the front side original image read by the CCD 209 and the back side original image read by the contact sensor 252, the contact sensor 252 reads it by the registration information obtained by the CCD 209. Since the registration information of the back side document is calculated, it is possible to omit the paper feed operation control and the image processing sequence for obtaining the registration information of the back side document, and it is possible to improve the reading performance.

In the above description, the case where the edge portion of the document can be detected has been described. However, when the background color of the document is a color close to the density of the document conveying roller 75, the image exists up to the edge of the document. In some cases, the edge of the document cannot be detected. In this case, the main scanning synchronization signals HSYNC_CCD and HS that were updated last time are updated without updating the output timing of the main scanning synchronization signals HSYNC_CCD and HSYNC_CS.
Control to output at the timing of YNC_CS. In this case, accurate registration adjustment is not performed, but since the approximate adjustment is performed, an extreme registration deviation does not occur.

Further, in the present embodiment, the resist adjustment is performed for each original, so that the accurate adjustment is performed. Even if the registration adjustment is not performed for each original, the registration adjustment may be performed once for a plurality of originals or for a predetermined period, so that performance is improved in exchange for accuracy. .

Further, in this embodiment, the range of effective image data is controlled by controlling the output timing of the main scanning synchronizing signal. Even if the output timing of the main scanning same signal is not controlled, for example, it may be controlled so that the pixel of any pixel after the output of the main scanning synchronization signal is determined as the effective image data. Any configuration that controls the range as effective image data is sufficient.

According to the present invention, a storage medium recording a program code of software for implementing the functions of the above-described embodiments is supplied to a system or apparatus, and the computer (CPU or MPU) of the system or apparatus is supplied.
Can also be achieved by reading and executing the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, C
D-ROM, CD-R, DVD-ROM, magnetic tape,
A non-volatile memory card, ROM or the like can be used.

[0059]

As described above, according to the present invention,
The image information read by the first reading unit includes a first reading unit that reads the image information on the first side of the document and a second reading unit that reads the image information on the second side of the document. Is output and the image information read by the second reading unit is output, it is possible to eliminate an image shift due to a subtle difference in document size and improve the reading performance.

[Brief description of drawings]

FIG. 1 is a schematic enlarged view showing a periphery of a conveyance roller in an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a relative positional relationship between a document and a CCD and CC
It is a figure which shows each pixel data read by D.

FIG. 3 is a diagram showing a relative positional relationship among a document, a CCD, and a contact sensor.

FIG. 4 is a timing chart showing output timings of main scanning synchronization signals HSYNC_CCD and HSYNC_CS with respect to a reading state of CCD when an edge is detected.

FIG. 5 is a timing chart showing an example in which the output timings of the main scanning synchronization signals HSYNC_CCD and HSYNC_CS are updated according to changes in the edge detection state.

FIG. 6 is a schematic configuration diagram of an image reading apparatus capable of 1-pass double-sided reading.

FIG. 7 is a top view showing a document table 71 of the ADF 70 shown in FIG.

[Explanation of symbols]

40 manuscripts 70 ADF 71 Document Plate 200 reading unit 209 CCD 250x magnification reading box 252 contact sensor

Claims (17)

[Claims] 1. A first reading unit for reading image information on a first side of a document, and a second reading unit for reading image information on a second side of the document. An image reading device for outputting the image information read by the means, and outputting the image information read by the second reading means, wherein the first document of the document is output based on the output of the first reading means.
Edge detecting means for detecting an edge portion on the surface of the image, a range of effective image data of image information output from the first reading means based on the detection result of the edge detecting means, and the second reading means. And an image reading device for changing the range of effective image data of image information. 2. The first reading unit and the second reading unit are line image sensors that read image information line by line, and the first reading unit of the original serves as a main scanning synchronization signal of the first reading unit. The main scanning synchronizing signal is output in synchronization with the first line image information on the first surface, and the main scanning synchronizing signal is output as the main scanning synchronization signal of the second reading unit to the first line image information on the second surface of the document. The image reading apparatus according to claim 1, wherein the image reading apparatus outputs a scan synchronization signal. 3. The changing means determines the output timing of the main scanning synchronization signal of the first reading means and the output timing of the main scanning synchronization signal of the second reading means based on the detection result of the edge detecting means. The image reading apparatus according to claim 2, wherein the image reading apparatus is changed. 4. The changing means, based on a detection result of the edge detecting means, a period from a main scanning synchronizing signal of the first reading means to valid image data and a main scanning synchronizing signal of the second reading means. The image reading apparatus according to claim 2, wherein a period until valid image data is changed. 5. A document feeding unit for feeding documents one by one, the second reading unit being provided in the automatic document feeding device, and sub-scanning with respect to the first reading sensor. The image reading apparatus according to claim 1, wherein the image reading apparatus is arranged at a downstream side position in the direction. 6. The method according to claim 1, wherein when the edge detection unit cannot detect an edge, the change unit prohibits the change of the effective image data range of each image information. The image reading device described in any one of the above. 7. The apparatus further comprises control means for controlling the edge portion to be detected by the edge detecting means and the range of the effective image data of each of the image information to be changed by the changing means every time the original is read. The image reading apparatus according to any one of claims 1 to 5. 8. The image reading apparatus according to claim 1, further comprising an output unit that outputs the effective image data. 9. A first reading unit for reading image information on a first side of a document, and a second reading unit for reading image information on a second side of the document, the first reading unit comprising: A method of controlling an image reading apparatus, which outputs image information read by a reading unit and outputs image information read by the second reading unit, wherein the document of the original is output based on an output of the first reading unit. First
Edge detection step of detecting an edge portion on the surface of the image, a range of effective image data of image information output from the first reading means based on the detection result of the edge detection step, and an output from the second reading means. And a change step of changing the range of effective image data of image information. 10. The first reading unit and the second reading unit are line image sensors for reading image information line by line, and the first scanning unit of the first reading sensor is a main scanning synchronization signal of the document. The main scanning synchronization signal that is synchronized with the first line image information on the surface of the document is output, and the second scanning of the document is performed as the main scanning synchronization signal of the second reading sensor.
10. The control method for the image reading apparatus according to claim 9, wherein the main scanning synchronizing signal is output in synchronization with the first line image information on the plane. 11. In the changing step, an output timing of a main scanning synchronization signal of the first reading means and an output timing of a main scanning synchronization signal of the second reading means are based on a detection result of the edge detection process. 11. The control method for the image reading apparatus according to claim 10, wherein: 12. In the changing step, the period from the main scanning synchronizing signal of the first reading means to the effective image data and the main scanning synchronizing signal of the second reading means are based on the detection result of the edge detecting step. 11. The method of controlling an image reading apparatus according to claim 10, wherein the period until the effective image data is changed. 13. The image reading device further includes a document feeding unit that feeds documents one by one, and the second reading unit is provided in the automatic document feeding device and is provided in the first reading unit. 13. The image reading apparatus control method according to claim 9, wherein the image reading apparatus is arranged at a downstream side position in the sub-scanning direction. 14. If the edge is not detected in the edge detecting step, the changing step prohibits the change of the effective image data range of each of the first and second image information. The control method for an image reading apparatus according to claim 9. 15. The method further comprising the step of controlling to update the range of the effective image data of each of the image information by executing the edge detecting step and the changing step every time the document is read. Item 15. The control method for the image reading device according to any one of Items 9 to 14. 16. The control method of the image reading apparatus according to claim 9, further comprising an output step of outputting the effective image data. 17. A first reading unit for reading image information on a first side of a document, and a second reading unit for reading image information on a second side of the document, wherein the first reading unit is provided. An image reading device for outputting the image information read by the means and outputting the image information read by the second reading means, the image reading device for outputting the first information of the document based on the output of the first reading means.
Edge detecting means for detecting an edge portion on the surface of the image, a range of effective image data of image information output from the first reading means based on the detection result of the edge detecting means, and the second reading means. A program for functioning as a changing unit that changes the range of effective image data of image information.