Image reading device

Abstract

The present invention provides an image reading device that produces a clear shadow on the leading edge side in the document transport direction. [Solution] The image reading device includes a reading unit 109A which is a reading means for reading a document being transported along a transport path, an illumination unit 110A which is a first illumination means that irradiates light from upstream of the reading position of the reading unit 109A toward the reading position in the transport direction of the document, an illumination unit 110B which is a second illumination means that irradiates light from downstream of the reading position toward the reading position, and a control means that controls the emission of light from the illumination unit 110A and the illumination unit 110B such that the amount of light from the first illumination means is greater than the amount of light from the second illumination means in a first range within the range of the transport path in the width direction perpendicular to the transport direction.

Description

Technical Field

[0001] The present invention relates to an image reading device that optically reads an image of a document being conveyed.

Background Art

[0002] An image reading device having an automatic document feeder (Auto Document Feeder: hereinafter, ADF) is used. The ADF feeds the documents placed on the document tray one by one into the conveyance path of the image reading device. The image reading device optically reads the image of the document while conveying the document along the conveyance path. In the image reading device, skew may occur in which the posture of the document during conveyance deviates from the ideal posture due to various factors. The ideal posture of the document during conveyance is, for example, a posture in which the side on the leading end side in the conveyance direction of the document coincides with the width direction orthogonal to the conveyance direction. When skew occurs, the image read by the image reading device also tilts obliquely.

[0003] For this reason, Patent Document 1 discloses a technique for detecting the angle of the side on the leading end side of the document with respect to the width direction by detecting the shadow generated by the side on the leading end side of the document in the conveyance direction, and correcting the read image based on the detected angle. Further, Patent Document 2 discloses a configuration in which a Laplacian filter is applied to the image data obtained by reading the document in order to detect the shadow generated by the side on the leading end side of the document.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] If the shadow cast by the leading edge of the document in the transport direction is blurred, applying a Laplacian filter to the image data obtained by scanning the document will not accurately detect the shadow.

[0006] This invention provides a technique for creating a clear shadow on the leading edge side in the document's transport direction. [Means for solving the problem]

[0007] According to one aspect of the present invention, an image reading device is a reading means for reading a document being transported along a transport path, the reading means having a first irradiating means that irradiates light toward the reading position of the reading means from an upstream side of the reading position in the transport direction of the document, and a second irradiating means that irradiates light toward the reading position from a downstream side of the reading position, and a control means that controls the emission of light from the first irradiating means and the second irradiating means such that in a first range within the range of the transport path in a width direction perpendicular to the transport direction, the amount of light from the first irradiating means is greater than the amount of light from the second irradiating means. [Effects of the Invention]

[0008] According to the present invention, a clear shadow can be produced on the leading edge side in the document transport direction. [Brief explanation of the drawing]

[0009] [Figure 1] Cross-sectional view of an image reading device. [Figure 2] Diagram of the reading unit's configuration. [Figure 3] This diagram shows an example of the relationship between the position in the width direction and the amount of light emitted by each of the two illumination sections of the reading unit. [Figure 4] A diagram illustrating the relationship between the amount of light emitted from each of the two illumination sections of the reading unit and the accuracy of shadow detection. [Figure 5] Control block diagram of the image reading device. [Figure 6] A flowchart for the process of setting control information. [Figure 7]A diagram illustrating the process of setting control information. [Figure 8] Diagram illustrating the edge detection process. [Figure 9] This figure shows an example image using image data after edge extraction processing. [Figure 10] Diagram illustrating the correction process. [Modes for carrying out the invention]

[0010] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0011] <First Embodiment> Figure 1 is a cross-sectional view of the image reading device 100 according to this embodiment. In the following description, unless it is clear from the context that it is not the transport direction, or unless it is explicitly stated that it is not the transport direction, "leading edge of the document" means the leading edge of the document in the transport direction. One or more documents 101 are placed on the document tray 102. The side regulating plate 123 has two regulating members configured to be movable in the width direction. The two regulating members are configured so that the distance from the center of the document tray 102 in the width direction is the same regardless of their position in the width direction. By regulating the positions of two sides of the document 101 placed on the document tray 102 that are parallel to the transport direction with the two regulating members, the center of the document 101 placed on the document tray 102 in the width direction coincides with the center of the document tray 102 in the width direction. At that time, the leading edge side of the document 101 placed on the document tray 102 coincides with the width direction.

[0012] The pickup roller 103 feeds the uppermost document 101 placed on the document tray 102 into the transport path of the image reading device 100. Separation rollers 104 and 105 are provided to prevent double feeding of documents 101. The documents 101 fed into the transport path are transported by rollers provided along the transport path.

[0013] The reading unit 109A reads the first side of the document 101 at reading position A. Reading position A is the position of the document 101 in the transport direction. The reading unit 109A has an illumination unit 110A that irradiates light toward reading position A from upstream of reading position A in the transport direction, and an illumination unit 110B that irradiates light toward reading position A from downstream of reading position A. A guide plate 116, which is a white material, is provided at reading position A. The guide plate 116 is a background material that serves as the background for the document 101 when the reading unit 109A reads the document 101. When the document 101 is not at reading position A, the light irradiated by illumination units 110A and 110B is reflected by the guide plate 116, and when the document 101 is at reading position A, the light irradiated by illumination units 110A and 110B is reflected by the document 101. The irradiation units 110A and 110B irradiate the original document 101 or the guide plate 116 with light via the glass 108.

[0014] The optical element 112 causes the reflected light, illuminated by the illumination unit 110A and illumination unit 110B and reflected by the document 101 or guide plate 116, to form an image on the image sensor 111. The image sensor 111 in this embodiment has 7500 pixels along the width direction, and each pixel has three different light-receiving elements that receive light of three colors: R (red), G (green), and B (blue). The image sensor 111 reads the document 101 as it is being transported in units of one line (7500 pixels) in the width direction. By repeatedly reading the document 101 with the image sensor 111 while the document 101 is passing through reading position A, image data corresponding to the document 101 is read.

[0015] The pressing rollers 114 and 115 stabilize the distance between the reading unit 109A and the document 101 by pressing the document 101. The reading unit 109B reads the second side of the document 101 through the glass 118 at a reading position B downstream of the reading position A. The configuration of the reading unit 109B is the same as that of the reading unit 109A. A guide plate 119, which is a white member, is provided at the reading position B. The sensor 113 detects the document 101 upstream of the reading position A. The timing when the sensor 113 detects the document 101 is used to determine the reading timing of the document 101 by the reading unit 109A and the reading unit 109B. The document 101 that has passed through the reading position B is placed on the tray 121 by the roller 120. The white reference plate 122, which is a white member, is a measuring member or a reference member that is measured by the reading unit 109A to obtain the shading data of the reading unit 109A. The reading unit 109A is configured to be movable to a position where it can read the white reference plate 122. That is, the reading unit 109A is configured to be movable between a position where its reading position is the reading position A and a position where its reading position is the white reference plate 122.

[0016] Figure 2(A) is an enlarged view of the area around reading position A. As shown in Figure 2(A), when the reading unit 109A irradiates light, a shadow is cast by the document 101 on the leading edge side of the document 101. Figure 2(B) is a detailed configuration diagram of the reading unit 109A. The irradiation unit 110A has a light source 132A and a light guide 133A. The irradiation unit 110B has a light source 132B and a light guide 133B. The light sources 132A and 132B are, for example, light-emitting diodes (LEDs). The light guide 133A propagates the light emitted by the light source 132A along the width direction, irradiating light toward reading position A in the process. Similarly, the light guide 133B propagates the light emitted by the light source 132B along the width direction, irradiating light toward reading position A in the process. Note that the direction in which light propagates through the light guide 133A is opposite to the direction in which light propagates through the light guide 133B. Ideally, the light guides 133A and 133B should irradiate light uniformly along the width direction, but in reality, the amount of light irradiated onto the document 101 changes depending on the position in the width direction. Specifically, the amount of light irradiated by the light guide 133A decreases as the distance from the light source 132A increases in the width direction. Similarly, the amount of light irradiated by the light guide 133B decreases as the distance from the light source 132B increases in the width direction. By making the light propagation directions of the light guides 133A and 133B opposite to each other, the difference in the amount of light irradiated depending on the position in the width direction can be reduced.

[0017] Figure 3 shows an example of the relationship between the position in the width direction and the amount of light emitted by the irradiating units 110A and 110B. The solid line in Figure 3 represents the amount of light emitted by irradiating unit 110A, and the dotted line represents the amount of light emitted by irradiating unit 110B. Irradiating unit 110A emits light from upstream of reading position A toward reading position A, while irradiating unit 110B emits light from downstream of reading position A toward reading position A. As is clear from Figure 2(A), the light from irradiating unit 110A creates the shadow on the leading edge of the document 101, while the light from irradiating unit 110B acts to eliminate the shadow on the leading edge of the document 101. Therefore, the intensity of the shadow on the leading edge of the document 101 changes depending on the position in the width direction. Specifically, the greater the amount of light emitted by irradiating unit 110A compared to the amount of light emitted by irradiating unit 110B, the darker the shadow becomes.

[0018] The upper part of FIG. 4 shows an image (hereinafter referred to as a read image) based on the image data read by the reading unit 109A. Since the reading by the reading unit 109A starts before the original document 101 reaches the reading position A, the guide plate 116, the shadow generated on the leading end side of the original document 101, and the original document 101 are read. The second from the top in FIG. 4 shows an image (hereinafter referred to as an edge image) obtained by performing edge extraction processing (binarization processing) on the image data read by the reading unit 109A. Note that the white part indicates the extracted edge. Also, the lower part of FIG. 4 shows the amount of irradiation light by the irradiation unit 110A and the amount of irradiation light by the irradiation unit 110B when the reading unit 109A performs reading. As shown in FIG. 4, in the range B where the amount of irradiation light by the irradiation unit 110A is higher than the amount of irradiation light by the irradiation unit 110B, the edge between the guide plate 116 and the shadow (hereinafter referred to as a shadow edge) is accurately extracted. On the other hand, in the range A where the amount of irradiation light by the irradiation unit 110A is lower than the amount of irradiation light by the irradiation unit 110B, the edge between the guide plate 116 and the shadow is not accurately extracted.

[0019] [[ID=,6]] Therefore, in order to accurately detect the shadow edge, it can be understood that the light emission of the light sources 132A and 132B should be controlled so that the amount of irradiation light by the irradiation unit 110A is larger than the amount of irradiation light by the irradiation unit 110B at least within the range where the original document 101 passes (hereinafter referred to as the original document range) within the range of the conveyance path in the width direction.

[0020] Figure 5 is a control block diagram of the image reading device 100. The controller 200 controls the entire image reading device 100. When the CPU 203 of the controller 200 receives a document reading instruction via the operation unit 202, it controls the transport motor 201 to control the feeding and transport of the document 101 placed on the document tray 102. The CPU 203 then controls the reading of the document 101 by the reading unit 109A and the reading unit 109B based on the detection result of the document 101 by the sensor 113. The reading unit 109A outputs digital first image data as the reading result of the first side of the document 101, and the reading unit 109B outputs digital second image data as the reading result of the second side of the document 101.

[0021] The first image data is transmitted to the shading circuit 204A, and the second image data is transmitted to the shading circuit 204B. The shading circuits 204A and 204B perform addition, subtraction, multiplication, and division on the image data to correct for the non-uniformity of the illumination light intensity from the illumination units 110A and 110B, and the effects of the sensitivity unevenness of each pixel of the image sensor 111, thereby generating image data that is uniform in the width direction.

[0022] The first image data after shading correction is stored in the image memory 205. The second image data after shading correction undergoes a widthwise inversion process in the inversion circuit 210 so that its width direction is the same as the first image data, and is then stored in the image memory 205. The first image data after shading correction is also transmitted to the edge extraction unit 206. The edge extraction unit 206 performs edge extraction processing on the first image data after shading correction to generate the edge image data described in Figure 4. The calculation unit 207 generates document information based on the edge image data and outputs it to the CPU 203. Details of the processing in the edge extraction unit 206 and the calculation unit 207 will be described later.

[0023] The CPU 203 outputs the original document information to the correction unit 208. The correction unit 208 corrects the first image data and the second image data stored in the image memory 205 based on the original document information. The non-volatile memory 209 stores control information indicating the emission conditions of the light sources 132A and 132B. The CPU 203 causes light source 132A to emit light based on the first emission condition indicated by the control information stored in the non-volatile memory 209, and light source 132B to emit light based on the second emission condition. The first emission condition is a condition for controlling the amount of light emitted by light source 132A, and the second emission condition is a condition for controlling the amount of light emitted by light source 132B. The emission conditions are, for example, conditions indicating the emission intensity and emission time of the light source. The emission intensity can be specified by the drive current flowing through the light source.

[0024] Figure 6 is a flowchart of the setting process for the first and second light emission conditions, indicated by the control information stored in the non-volatile memory 209. The setting process is executed when instructed by the user via the operation unit 202 or when predetermined conditions are met. In S10, the CPU 203 moves the reading unit 109A to a position where it can read the white reference plate 122.

[0025] In S11, the CPU 203 illuminates only the light source 132A based on the third light emission condition, causing the reading unit 109A to read the white reference plate 122. The third light emission condition is a predetermined condition stored in the non-volatile memory 209 beforehand. As an example, the third light emission condition is a condition where the light emission time is 300 μs and the drive current is 50 mA. The reading result of the white reference plate 122 is the amount of light received by each pixel of the image sensor 111, that is, the amount of irradiated light at each position in the width direction, and can also be referred to as a brightness value. In S12, the CPU 203 saves the reading result from S11 as the first reading result in the image memory 205. In S13, the CPU 203 illuminates only the light source 132B based on the third light emission condition, causing the reading unit 109A to read the white reference plate 122. In S14, the CPU 203 saves the reading result from S13 as the second reading result in the image memory 205.

[0026] In S15, the CPU 203 generates a fourth light emission condition based on the first and second reading results. The fourth light emission condition is a condition that makes the amount of light emitted at each position within the document range, when the white reference plate 122 is read with only the light source 132B emitting light based on the fourth light emission condition, smaller than the amount of light emitted at the same position indicated by the first reading result. Figure 7 shows an example of the relationship between the first, second, and third reading results. The third reading result is the reading result when the white reference plate 122 is read with only the light source 132B emitting light based on the fourth light emission condition. The third reading result is basically the second reading result shifted by the difference between the amount of light emitted by the light source 132B based on the third light emission condition and the amount of light emitted by the light source 132B based on the fourth light emission condition.

[0027] Returning to Figure 6, in S16, the CPU 203 causes light source 132A to emit light based on the third emission condition and light source 132B to emit light based on the fourth emission condition, causing the reading unit 109A to read the white reference plate 122 and obtain the fourth reading result. The CPU 203 determines whether the total amount of irradiated light at each position in the width direction indicated by the fourth reading result is below a predetermined threshold. If the total amount of irradiated light at each position is below the predetermined threshold, in S19, the CPU 203 stores the third emission condition as the first emission condition and the fourth emission condition as the second emission condition in the non-volatile memory 209.

[0028] If the total amount of irradiated light at each position is not below a predetermined threshold, the CPU 203 determines that the image sensor 111 is saturated. In this case, in S18, the CPU 203 adjusts the third and fourth emission conditions to reduce the amount of light emitted from light source 132A and light emitted from light source 132B by the same proportion, and repeats the process from S16. The CPU 203 can reduce the amount of light emitted by controlling one or both of the emission time and drive current.

[0029] In S17, when the total amount of irradiated light at each position in the width direction indicated by the fourth reading result falls below a predetermined threshold, the CPU 203 stores the adjusted third emission condition as the first emission condition and the adjusted fourth emission condition as the second emission condition in the non-volatile memory 209 in S19. Note that instead of setting the total amount of irradiated light at each position in the entire width direction range read by the reading unit 109A below a predetermined threshold, the configuration may also be such that the total amount of irradiated light at each position within the document range falls below a predetermined threshold.

[0030] When scanning a document, the CPU 203 illuminates light source 132A based on a first emission condition and light source 132B based on a second emission condition. This configuration allows a dark shadow, or a clear shadow, to be created on the leading edge of the document 101. Furthermore, the document 101 can be scanned without saturating the image sensor 111.

[0031] In Figure 6, based on the first and second reading results, a fourth light emission condition was determined, which is to make the amount of light illuminating each position within the document range less than the amount of light illuminating the same position indicated by the first reading result when the white reference plate 122 is read with only the light source 132B illuminating. However, it is also possible to configure the system to determine a fifth light emission condition, which is to make the amount of light illuminating each position within the document range greater than the amount of light illuminating the same position indicated by the second reading result when the white reference plate 122 is read with only the light source 132A illuminating. In this case, the CPU 203 illuminates the light source 132B based on the third light emission condition and illuminates the light source 132A based on the fifth light emission condition, and then has the reading unit 109A read the white reference plate 122 to obtain the fourth reading result. If the CPU 203 finds that the total amount of irradiated light at each position in the width direction indicated by the fourth reading result is not below a predetermined threshold, it adjusts the third and fifth emission conditions to reduce the amount of light emitted from light source 132B and light emitted from light source 132A by the same proportion. Then, the CPU 203 sets the third emission condition as the second emission condition and the fifth emission condition as the first emission condition.

[0032] Furthermore, in Figure 6, the first and second reading results were acquired, and the fourth control information was determined based on the first and second reading results. However, after acquiring the first reading result, the fourth emission condition may also be determined by repeatedly acquiring reading results while emitting light from the light source 132B under various conditions so that the amount of light irradiated at each position within the document range is smaller than the amount of light irradiated at the same position in the first reading result. Similarly, after acquiring the second reading result with the third emission condition, the fifth emission condition can also be determined by emitting light from the light source 132A under various conditions so that the amount of light irradiated at each position within the document range is larger than the amount of light irradiated at the same position in the second reading result.

[0033] Furthermore, in Figure 6, the first and second light emission conditions were set using the third light emission condition. However, if it is possible to set a second light emission condition that does not saturate the image sensor 111 based on the first light emission condition, the configuration can also be such that the second light emission condition is set based on the first light emission condition.

[0034] For example, the CPU 203 obtains a first reading result by illuminating only the light source 132A according to the first light emission condition, and obtains a second reading result by illuminating only the light source 132B according to the first light emission condition. Then, based on the first and second reading results, the CPU 203 may set a second light emission condition that makes the amount of illumination light at each position within the document range when the white reference plate 122 is read with only the light source 132B illuminated smaller than the amount of illumination light at the same position indicated in the first reading result.

[0035] Alternatively, after acquiring the first reading result, the CPU 203 can set a second illumination condition by repeatedly reading the white reference plate 122 while only the light source 132B is emitting light, while changing the amount of light emitted by the light source 132B.

[0036] Similarly, if it is possible to set a first light emission condition that does not saturate the image sensor 111 based on the second light emission condition, a configuration can also be used in which the first light emission condition is set based on the second light emission condition.

[0037] For example, the CPU 203 obtains a first reading result by illuminating only light source 132A according to the second light emission condition, and obtains a second reading result by illuminating only light source 132B according to the second light emission condition. Then, based on the first and second reading results, the CPU 203 may set a first light emission condition such that the amount of illumination light at each position within the document range when the white reference plate 122 is read with only light source 132A illuminated is greater than the amount of illumination light at the same position indicated by the second reading result.

[0038] Alternatively, the CPU 203 can set the first illumination condition by acquiring only the second reading result and then repeatedly reading the white reference plate 122 while only the light source 132A is illuminated, while changing the amount of light emitted by the light source 132A.

[0039] Furthermore, in Figure 6, a white reference plate 122 was used as the measuring element, and the first and second emission conditions were determined based on the reading results. However, it is also possible to use a white guide plate 116 as the measuring element and determine the first and second emission conditions based on the reading results of the guide plate 116. Moreover, in this embodiment, the fourth emission condition was a condition in which the amount of irradiated light at each position within the document range when only the light source 132B is lit is smaller than the amount of irradiated light at the same position in the first reading result. However, the fourth emission condition can be a condition in which the total amount of irradiated light within the document range when only the light source 132B is lit, that is, the integral value of the amount of irradiated light at each position, is smaller than the total amount of irradiated light within the document range indicated by the first reading result. The same applies to the fifth emission condition. In other words, the fifth emission condition can be a condition in which the total amount of irradiated light within the document range when only the light source 132A is lit is greater than the total amount of irradiated light within the document range indicated by the second reading result.

[0040] Figure 8 shows an example of a filter used in the edge extraction process in the edge extraction unit 206. The edge extraction process is also a binarization process. The filter shown in Figure 8 is a 3x3 pixel filter. The edge extraction unit 206 applies the filter shown in Figure 8 to the first image data from the shading circuit 204A and determines the amount of light (luminance value) of the pixels corresponding to the filter in the first image data. As is clear from the upper image in Figure 4, if an edge exists within the area to which the filter is applied, the maximum difference in luminance values ​​of the 9 pixels becomes large. On the other hand, if no edge exists within the area to which the filter is applied, the maximum difference in luminance values ​​of the 9 pixels becomes small. Therefore, if the maximum difference in luminance values ​​of the 9 pixels is greater than the threshold, the edge extraction unit 206 determines the central pixel, that is, the pixel of the first image data corresponding to P4 in Figure 8, to be an edge pixel. The edge extraction unit 206 determines edge pixels while shifting the area to which the filter is applied within the document area. As described above, the edge extraction unit 206 outputs the edge image data after the edge extraction process to the calculation unit 207.

[0041] Figure 9 shows the image represented by the edge image data. As described above, since the reading unit 109A performs reading before the document 101 reaches reading position A, the calculation unit 207 receives the edge image data of the image within the range shown by the dotted line in Figure 8. As described above, the image sensor 111 has 7500 pixels, so the number of pixels in the width direction is 7500. According to Figure 9, the number of pixels in the transport direction is 12000. In the following explanation, the upper left pixel in Figure 9 is taken as the origin, and the position of the x-th pixel along the width direction from the origin, and the y-th pixel along the direction opposite to the transport direction from the origin, is denoted as position (x-1, y-1).

[0042] The calculation unit 207 determines the leading edge angle θ1 and the pixel position (x1, y1) in the edge image data on the left side of the leading edge of the original document 101 based on the shadow on the leading edge of the original document 101, and transmits original document information indicating the leading edge angle θ1 and position (x1, y1) to the CPU 203. The CPU 203 transmits the original document information to the correction unit 208.

[0043] The correction unit 208 performs rotational correction on the first image data and the second image data stored in the image memory 205 based on the document tip angle θ1. Figure 10(A) shows the image after rotational correction of the first image data. Next, the correction unit 208 performs shift correction on the first image data and the second image data after rotational correction, shifting the document position so that the position on the left side of the tip (x1, y1) becomes the origin. Figure 10(B) shows the image after shift correction of the first image data.

[0044] [Other embodiments] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0045] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0046] 109A: Reading unit, 110A, 110B: Irradiation unit, 200: Controller

Claims

1. A reading means for reading a document being transported along a transport path, comprising: a first irradiation means for irradiating light from upstream of the reading position of the reading means toward the reading position in the transport direction of the document; and a second irradiation means for irradiating light from downstream of the reading position toward the reading position. In a first range within the range of the transport path in the width direction perpendicular to the transport direction, a control means controls the emission of light from the first and second irradiating means such that the amount of light from the first irradiating means is greater than the amount of light from the second irradiating means. An image reading device equipped with [a specific feature].

2. The image reading device according to claim 1, wherein the first range includes the range in the transport path through which the document passes.

3. The first irradiation means comprises a first light source and a first light guide that irradiates the reading position while propagating the light from the first light source in the width direction, The second irradiation means comprises a second light source and a second light guide that irradiates the reading position with light from the second light source while propagating it in the width direction in the opposite direction to the first light guide. The image reading device according to claim 1, wherein the control means controls the emission of light from the first light source and the second light source, thereby controlling the emission of light from the first irradiation means and the second irradiation means.

4. The image reading device according to claim 3, wherein the control means controls the amount of light emitted from the first light source and the second light source by controlling at least one of the light emission intensity and light emission time of the first light source and the second light source.

5. The system further includes storage means for storing control information, The image reading device according to claim 3, wherein the control means controls the emission of light from the first light source in accordance with the first emission condition indicated by the control information when reading the original document, and controls the emission of light from the second light source in accordance with the second emission condition indicated by the control information.

6. The image reading device according to claim 5, wherein the control means reads a measuring member while only the first light source is emitting light according to a third light emission condition to obtain a first reading result indicating the relationship between the position in the width direction and the amount of light, reads a measuring member while only the second light source is emitting light according to a third light emission condition to obtain a second reading result indicating the relationship between the position in the width direction and the amount of light, and sets the first light emission condition and the second light emission condition based on the first reading result and the second reading result.

7. The control means is Based on the first and second reading results, a fourth light emission condition is determined such that the light intensity in the first range when the measuring member is read while only the second light source is emitting light is less than the light intensity in the first range indicated by the first reading result. The image reading device according to claim 6, wherein the first light source is made to emit light according to the third light emission condition and the second light source is made to emit light according to the fourth light emission condition, and the measuring member is read while the first light source is made to emit light according to the fourth light emission condition, thereby obtaining a third reading result that shows the relationship between the position in the width direction and the amount of light, and the amount of light emitted from the first light source according to the third light emission condition and the amount of light emitted from the second light source according to the fourth light emission condition are adjusted in the same proportion so that the amount of light at each position in the width direction shown in the third reading result is less than or equal to a predetermined threshold, and the adjusted third light emission condition is set as the first light emission condition and the adjusted fourth light emission condition is set as the second light emission condition.

8. The control means is Based on the first and second reading results, a fifth light emission condition is determined such that the light intensity in the first range when the measuring member is read while only the first light source is emitting light is greater than the light intensity in the first range indicated by the second reading result. The image reading device according to claim 6, wherein the first light source is made to emit light according to the fifth light emission condition and the second light source is made to emit light according to the third light emission condition, and the measuring member is read while the light is being read, thereby obtaining a third reading result that shows the relationship between the position in the width direction and the amount of light, the amount of light emitted from the first light source according to the fifth light emission condition and the amount of light emitted from the second light source according to the third light emission condition are adjusted in the same proportion so that the amount of light at each position in the width direction shown in the third reading result is less than or equal to a predetermined threshold, the adjusted fifth light emission condition is set as the first light emission condition and the adjusted third light emission condition is set as the second light emission condition.

9. The control means is By reading the measuring member while only the first light source is emitting light according to the third emission condition, a first reading result showing the relationship between the position in the width direction and the amount of light is obtained, and by repeatedly reading the measuring member while only the second light source is emitting light, while changing the amount of light emitted by the second light source, a fourth emission condition is determined in which the amount of light in the first range is smaller than the amount of light in the first range shown in the first reading result. The image reading device according to claim 5, wherein the first light source is made to emit light according to the third light emission condition and the second light source is made to emit light according to the fourth light emission condition, and the measuring member is read while the light is being read, thereby obtaining a third reading result that shows the relationship between the position in the width direction and the amount of light, and the amount of light emitted from the first light source according to the third light emission condition and the amount of light emitted from the second light source according to the fourth light emission condition are adjusted in the same proportion so that the amount of light at each position in the width direction shown in the third reading result is less than or equal to a predetermined threshold, and the adjusted third light emission condition is set as the first light emission condition and the adjusted fourth light emission condition is set as the second light emission condition.

10. The control means is By reading the measuring member while only the second light source is emitting light according to the third emission condition, a second reading result showing the relationship between the position in the width direction and the light intensity is obtained, and by repeatedly reading the measuring member while only the first light source is emitting light, while changing the amount of light emitted by the first light source, a fifth emission condition is determined in which the light intensity in the first range is greater than the light intensity in the first range shown in the second reading result. The image reading device according to claim 5, wherein the first light source is made to emit light according to the fifth light emission condition and the second light source is made to emit light according to the third light emission condition, and the measuring member is read while the member is being read, thereby obtaining a third reading result that shows the relationship between the position in the width direction and the amount of light, and the amount of light emitted from the first light source according to the fifth light emission condition and the amount of light emitted from the second light source according to the third light emission condition are adjusted in the same proportion so that the amount of light at each position in the width direction shown in the third reading result is less than or equal to a predetermined threshold, and the adjusted fifth light emission condition is set as the first light emission condition and the adjusted third light emission condition is set as the second light emission condition.

11. The image reading device according to claim 5, wherein the control means reads the measuring member while only the first light source is emitting light according to the first light emission condition, thereby obtaining a first reading result indicating the relationship between the position in the width direction and the amount of light; reads the measuring member while only the second light source is emitting light according to the first light emission condition, thereby obtaining a second reading result indicating the relationship between the position in the width direction and the amount of light; and based on the first reading result and the second reading result, sets a second light emission condition such that the amount of light in the first range when the measuring member is read while only the second light source is emitting light is less than the amount of light in the first range indicated by the first reading result.

12. The image reading device according to claim 5, wherein the control means reads a measuring member while only the first light source is emitting light according to the first light emission condition, thereby obtaining a first reading result indicating the relationship between the position in the width direction and the amount of light, and sets a second light emission condition by repeatedly reading the measuring member at the reading position while only the second light source is emitting light, while changing the amount of light emitted by the second light source, thereby making the amount of light in the first range smaller than the amount of light in the first range indicated by the first reading result.

13. The image reading device according to claim 5, wherein the control means reads the measuring member while only the second light source is emitting light according to the second emission condition, thereby obtaining a second reading result indicating the relationship between the position in the width direction and the amount of light; reads the measuring member while only the first light source is emitting light according to the second emission condition, thereby obtaining a first reading result indicating the relationship between the position in the width direction and the amount of light; and based on the first reading result and the second reading result, sets a first emission condition such that the amount of light in the first range when the measuring member is read while only the first light source is emitting light is greater than the amount of light in the first range indicated by the second reading result.

14. The image reading device according to claim 5, wherein the control means reads a measuring member while only the second light source is emitting light according to the second light emission condition, thereby obtaining a second reading result indicating the relationship between the position in the width direction and the amount of light, and sets a first light emission condition by repeatedly reading the measuring member while only the first light source is emitting light, while changing the amount of light emitted by the first light source, thereby making the amount of light in the first range greater than the amount of light in the first range indicated by the second reading result.

15. The image reading device according to any one of claims 6 to 10, wherein the third emission condition is a predetermined condition.

16. The image reading device according to any one of claims 6 to 10, wherein the measuring member is a white member.

17. The image reading device according to any one of claims 6 to 14, wherein the measuring member is a background member when the reading means reads the document.

18. The image reading device according to any one of claims 6 to 14, wherein the control means moves the reading means so that the measuring member is at the reading position of the reading means when the reading means reads the measuring member.

19. The image reading device according to any one of claims 5 to 14, wherein, at each position within the first range, the amount of light emitted by the first irradiating means when the first light source is emitted according to the first emission condition is greater than the amount of light emitted by the second irradiating means when the second light source is emitted according to the second emission condition.

20. The image reading device according to any one of claims 5 to 14, wherein the total amount of light in the first range irradiated by the first irradiation means when the first light source is emitted according to the first emission condition is greater than the total amount of light in the first range irradiated by the second irradiation means when the second light source is emitted according to the second emission condition.

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