Image reading device, image reading method, and control program

Abstract

To provide an image reading device, an image reading method, and a control program capable of suppressing occurrence of moire within image data.SOLUTION: The image reading device comprises: a reading unit which comprises a line sensor for reading a reading object line by line and reads the reading object with a first resolution to generate image data with the first resolution; and an image processing unit which converts the image data with the first resolution to image data with a second resolution lower than the first resolution and outputs the image data. The reading unit makes an exposure time per a single line in a case of reading the reading object with the first resolution shorter than an exposure time in a case of reading the reading object with the second resolution.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an image reading apparatus, an image reading method, and a control program. [Background technology]

[0002] In image reading devices such as scanners that read an object and generate image data, there is a demand for improving the quality of the image data. Image data generated by image reading devices may have moire (interference fringes).

[0003] A color image reading device has been disclosed that reads an original image by sequentially lighting multiple color light sources along a scanning line (see Patent Document 1). This color image reading device sets the ratio of the number of times each color light source is turned on so that it is not the same for all of the light sources, performs thinning control of the lighted lines according to the ratio of the number of times the light sources are turned on, and synthesizes the read data for each color obtained by the thinning control in a predetermined combination. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-319138 A Summary of the Invention [Problem to be solved by the invention]

[0005] In an image reading device, it is desirable to suppress the occurrence of moire in generated image data.

[0006] An object of the present invention is to provide an image reading device, an image reading method, and a control program that are capable of suppressing the occurrence of moire in image data. [Means for solving the problem]

[0007] An image reading device according to one aspect of the present invention includes a line sensor that reads an object to be read line by line, and has a reading unit that reads the object to be read at a first resolution and generates image data at the first resolution, and an image processing unit that converts the image data at the first resolution into image data at a second resolution lower than the first resolution and outputs the image data, and the reading unit makes the exposure time per line when reading the object to be read at the first resolution shorter than the exposure time when reading the object to be read at the second resolution.

[0008] An image reading method according to one aspect of the present invention includes converting image data of a first resolution generated by reading the object to be read at a first resolution using a reading unit including a line sensor that reads the object line by line, into image data of a second resolution lower than the first resolution, and outputting the image data, wherein the reading unit makes the exposure time per line when reading the object to be read at the first resolution shorter than the exposure time when reading the object to be read at the second resolution.

[0009] A control program according to one aspect of the present invention is a control method for an image reading device having a reading unit that includes a line sensor that reads an object to be read line by line and that reads the object at a first resolution to generate image data at the first resolution, and causes the image reading device to convert the image data at the first resolution into image data at a second resolution lower than the first resolution and output the image data, and the reading unit sets the exposure time per line when reading the object to be read at the first resolution to be shorter than the exposure time when reading the object to be read at the second resolution. Effect of the Invention

[0010] According to the present invention, the image reading device, the image reading method, and the control program are capable of suppressing the occurrence of moire in image data. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view showing an image reading device according to an embodiment; [Diagram 2]FIG. 2 is a diagram for explaining a transport path inside an image reading device according to an embodiment. [Diagram 3] FIG. 1 is a schematic diagram for explaining an imaging device according to an embodiment. [Figure 4] 1 is a block diagram showing a schematic configuration of an image reading apparatus according to an embodiment; [Diagram 5] FIG. 1 is a diagram showing a schematic configuration of a storage device and a processing circuit according to an embodiment. [Figure 6] FIG. 4 is a schematic diagram illustrating an example of a data structure of a setting table. [Figure 7] 1A and 1B are schematic diagrams for explaining the colors of light irradiated onto a medium. [Figure 8] FIG. 4 is a schematic diagram for explaining a control signal. [Figure 9] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 10] 13A and 13B are diagrams illustrating an example of a configuration of an image reading device according to another embodiment. [Figure 11] FIG. 11 is a cross-sectional view of an image reading device according to another embodiment. [Figure 12] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 13] FIG. 13 is a diagram showing a schematic configuration of a processing circuit in an image reading device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an image reading device, an image reading method, and a control program according to one aspect of the present invention will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to the embodiments, but extends to the inventions described in the claims and their equivalents.

[0013] 1 is a perspective view showing an image reading device configured as an image scanner according to one embodiment. The image reading device 100 conveys a medium, which is an original, and captures an image. The medium is an example of an object to be read, and is paper, cardboard, a card, or the like. The image reading device 100 may be a facsimile, a copier, a multifunction printer (MFP, Multifunction Peripheral), or the like.

[0014] The image reading device 100 includes a lower housing 101, an upper housing 102, a placement table 103, a discharge table 104, an operation device 105, a display device 106, and the like.

[0015] The upper housing 102 is disposed at a position that covers the top surface of the image reading device 100, and engages with the lower housing 101 by a hinge so as to be openable and closable when loading a medium or cleaning the inside of the image reading device 100, for example.

[0016] The placement stage 103 is engaged with the lower housing 101 so that the medium to be transported can be placed thereon. The ejection stage 104 is engaged with the upper housing 102 so that the ejected medium can be held thereon. The ejection stage 104 may be engaged with the lower housing 101.

[0017] The operation device 105 has an input device such as a button and an interface circuit for acquiring a signal from the input device, accepts an input operation by a user, and outputs an operation signal according to the input operation by the user. The display device 106 has a display including a liquid crystal, an organic EL (Electro-Luminescence), or the like, and an interface circuit for outputting image data to the display, and displays the image data on the display.

[0018] 1, arrow A1 indicates the medium transport direction, arrow A2 indicates the width direction perpendicular to the medium transport direction, and arrow A3 indicates the height direction perpendicular to the medium transport direction and the width direction. In the following, upstream refers to the upstream side of the medium transport direction A1, and downstream refers to the downstream side of the medium transport direction A1.

[0019] FIG. 2 is a diagram for explaining a transport path inside the image reading device according to an embodiment.

[0020] The transport path inside the image reading device 100 includes a medium sensor 111, a feed roller 112, a separation roller 113, a first transport roller 114, a second transport roller 115, an imaging device 116, a third transport roller 117, and a fourth transport roller 118. The feed roller 112, the separation roller 113, the first transport roller 114, the second transport roller 115, the third transport roller 117, and the fourth transport roller 118 are an example of a transport unit that transports a medium. The number of each roller is not limited to one, and each roller may be multiple. In this case, the rollers are arranged side by side at intervals in the width direction A2.

[0021] The image reading device 100 has a so-called straight path. The top surface of the lower housing 101 forms a lower guide 107a of the medium transport path, and the bottom surface of the upper housing 102 forms an upper guide 107b of the medium transport path. The lower guide 107a is an example of a guide portion that guides the medium.

[0022] The media sensor 111 is disposed upstream of the feed roller 112 and the separation roller 113. The media sensor 111 has a contact detection sensor and detects whether or not a medium is placed on the placement table 103. The media sensor 111 generates and outputs a first media signal whose signal value changes depending on whether or not a medium is placed on the placement table 103. Note that the media sensor 111 is not limited to a contact detection sensor, and any other sensor capable of detecting the presence or absence of a medium, such as a light detection sensor, may be used as the media sensor 111.

[0023] The feed roller 112 is provided in the lower housing 101, and feeds the media placed on the placement table 103 from the bottom up. The separation roller 113 is a so-called brake roller or retard roller, and is provided in the upper housing 102, and is disposed opposite the feed roller 112. The feed roller 112 and the separation roller 113 function as a separation unit that separates the media.

[0024] The first transport roller 114 and the second transport roller 115 are disposed downstream of the feed roller 112 and the separation roller 113 so as to face each other, and transport the medium fed by the feed roller 112 and the separation roller 113 to the imaging device 116.

[0025] The third conveyor roller 117 and the fourth conveyor roller 118 are disposed downstream of the imaging device 116 and facing each other, and discharge the medium conveyed by the first conveyor roller 114 and the second conveyor roller 115 onto the discharge table 104.

[0026] The medium placed on the mounting table 103 is transported between the lower guide 107a and the upper guide 107b in the medium transport direction A1 by the rotation of the feed roller 112 in the direction of the arrow A4 in Fig. 2. The separation roller 113 rotates in the direction of the arrow A5 in Fig. 2 or stops when transporting the medium. When multiple media are placed on the mounting table 103, the feed roller 112 and the separation roller 113 function to separate only the media placed on the mounting table 103 that is in contact with the feed roller 112. This limits the transport of media other than the separated media (preventing double feeding).

[0027] The medium is fed between the first conveyor roller 114 and the second conveyor roller 115 while being guided by the lower guide 107a and the upper guide 107b. The medium is fed between the first imaging device 116a and the second imaging device 116b by the first conveyor roller 114 and the second conveyor roller 115 rotating in the directions of the arrows A6 and A7 in Fig. 2, respectively. The medium read by the imaging device 116 is discharged onto the discharge tray 104 by the third conveyor roller 117 and the fourth conveyor roller 118 rotating in the directions of the arrows A8 and A9 in Fig. 2, respectively.

[0028] FIG. 3 is a schematic diagram for explaining an imaging device according to an embodiment.

[0029] The imaging device 116 is an example of a reading unit, and reads a medium to generate read image data. The read image data is an example of image data generated by the reading unit. As shown in Fig. 2, the imaging device 116 is disposed downstream of the first conveying roller 114 and the second conveying roller 115 and upstream of the third conveying roller 117 and the fourth conveying roller 118. The imaging device 116 includes a first imaging device 116a and a second imaging device 116b. The first imaging device 116a and the second imaging device 116b are disposed near the conveying path of the medium, facing each other across the conveying path.

[0030] 3, the first imaging device 116a includes a first light emitting device 121a, a first line sensor 122a, and a first backing member 123a, etc. The second imaging device 116b includes a second light emitting device 121b, a second line sensor 122b, and a second backing member 123b, etc.

[0031] The first light emitting device 121a is provided on the opposite side of the second backing member 123b across the medium transport path. The first light emitting device 121a is a light source that irradiates light onto the transported medium, and includes a first red light emitting device 124a, a first green light emitting device 125a, and a first blue light emitting device 126a. The first red light emitting device 124a, the first green light emitting device 125a, and the first blue light emitting device 126a irradiate red, green, and blue light, respectively, onto the transported medium. The first light emitting device 121a irradiates light onto the surface of the medium transported to the position of the imaging device 116.

[0032] Similarly, the second light emitting device 121b is provided on the opposite side of the first backing member 123a across the medium transport path. The second light emitting device 121b is a light source that irradiates light onto the transported medium, and includes a second red light emitting device 124b, a second green light emitting device 125b, and a second blue light emitting device 126b. The second red light emitting device 124b, the second green light emitting device 125b, and the second blue light emitting device 126b irradiate light having red, green, and blue colors, respectively, onto the transported medium. The second light emitting device 121b irradiates light onto the back side of the medium transported to the position of the imaging device 116.

[0033] The first line sensor 122a is provided on the opposite side of the second backing member 123b across the medium transport path. The first line sensor 122a has an imaging sensor based on a CIS (Contact Image Sensor) of a life-size optical system type having imaging elements based on CMOS (Complementary Metal Oxide Semiconductor) linearly arranged in the main scanning direction. Each imaging element outputs an electrical signal having a signal value corresponding to each RGB color. In order to ensure processing performance, it is preferable that the first line sensor 122a has an output port of six or more channels. In addition, the first imaging device 116a has a lens that forms an image on the imaging element, and an A / D converter that amplifies and converts the electrical signal output from the imaging element into analog / digital (A / D). At the imaging position L1, the first line sensor 122a reads the surface of the transported medium line by line and generates read image data.

[0034] Similarly, the second line sensor 122b is provided on the opposite side of the first backing member 123a across the medium transport path. The second line sensor 122b has a line sensor based on a CIS of a life-size optical system type having CMOS imaging elements linearly arranged in the main scanning direction. Each imaging element outputs an electrical signal having a signal value corresponding to each RGB color. In order to ensure processing performance, the second line sensor 122b preferably has an output port of six or more channels. In addition, the second imaging device 116b has a lens that forms an image on the imaging element, and an A / D converter that amplifies and analog-to-digital converts the electrical signal output from the imaging element. The second line sensor 122b reads the back side of the transported medium line by line at the imaging position L2, and generates read image data.

[0035] The first line sensor 122a and the second line sensor 122b are one-line monochrome sensors, and identify the component values ​​of each RGB color of the object to be read while switching the color of light irradiated by the first light-emitting device 121a and the second light-emitting device 121b. The one-line monochrome sensor is less expensive than a three-line color sensor having three line sensors corresponding to each RGB color. Therefore, the image reading device 100 can reduce the device cost by using the one-line monochrome sensors as the first line sensor 122a and the second line sensor 122b.

[0036] In addition, instead of the line sensor based on a CIS of the equal magnification optical system type having an imaging element based on a CMOS, a line sensor based on a CIS of the equal magnification optical system type having an imaging element based on a CCD (Charge Coupled Device) may be used. Also, a line sensor based on a reduced optical system type having an imaging element based on a CMOS or a CCD may be used. Also, either one of the set of the first light emitting device 121a, the first line sensor 122a, and the second backing member 123b or the set of the second light emitting device 121b, the second line sensor 122b, and the first backing member 123a may be omitted.

[0037] The first backing member 123a is provided at a position facing the second light emitting device 121b and the second line sensor 122b. The surface of the first backing member 123a facing the second line sensor 122b has, for example, a white color, and the first backing member 123a functions as a white reference member for performing image correction such as shading based on an image signal captured by the first backing member 123a.

[0038] Similarly, the second backing member 123b is provided at a position facing the first light emitting device 121a and the first line sensor 122a. The surface of the second backing member 123b facing the first line sensor 122a has, for example, a white color, and the second backing member 123b functions as a white reference member for performing image correction such as shading based on an image signal captured by the second backing member 123b.

[0039] Hereinafter, first light emitting device 121a and second light emitting device 121b may be collectively referred to as light emitting device 121. Also, first red light emitting device 124a and second red light emitting device 124b may be collectively referred to as red light emitting device 124. Also, first green light emitting device 125a and second green light emitting device 125b may be collectively referred to as green light emitting device 125. Also, first blue light emitting device 126a and second blue light emitting device 126b may be collectively referred to as blue light emitting device 126. Also, first line sensor 122a and second line sensor 122b may be collectively referred to as line sensor 122.

[0040] FIG. 4 is a block diagram showing a schematic configuration of an image reading apparatus according to an embodiment.

[0041] In addition to the above-mentioned components, the image reading device 100 further includes a drive source 131, an interface device 132, a storage device 140, a processing circuit 150, and the like.

[0042] The driving source 131 includes one or more motors. The driving source 131 rotates the feed roller 112, the separation roller 113, the first conveyor roller 114, the second conveyor roller 115, the third conveyor roller 117, and / or the fourth conveyor roller 118 in response to a control signal from the processing circuit 150 to convey the medium. Note that one of the first conveyor roller 114 and the second conveyor roller 115 may be a driven roller that rotates following the other roller. Also, one of the third conveyor roller 117 and the fourth conveyor roller 118 may be a driven roller that rotates following the other roller.

[0043] The interface device 132 has an interface circuit conforming to a serial bus such as a Universal Serial Bus (USB). The interface device 132 is electrically connected to an information processing device (such as a personal computer, a portable information terminal, etc.) to transmit and receive a scanned image and various information. Instead of the interface device 132, a communication unit having an antenna for transmitting and receiving a wireless signal and a wireless communication interface device for transmitting and receiving a signal through a wireless communication line according to a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network).

[0044] The storage device 140 includes a memory device such as a RAM (Random Access Memory) or a ROM (Read Only Memory), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or an optical disk. The storage device 140 also stores computer programs, databases, tables, and the like used for various processes of the image reading device 100. The computer programs may be installed in the storage device 140 from a computer-readable portable recording medium using a known setup program or the like. The portable recording medium is, for example, a CD-ROM (Compact Disc Read Only Memory) or a DVD-ROM (Digital Versatile Disc Read Only Memory). The computer programs may be distributed from a server or the like and installed in the storage device 140. The storage device 140 also stores a setting table as data. The setting table will be described in detail later.

[0045] The processing circuit 150 operates based on a program previously stored in the storage device 140. The processing circuit 150 is, for example, a CPU (Central Processing Unit). As the processing circuit 150, a DSP (digital signal processor), an LSI (large scale integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like may be used.

[0046] The processing circuit 150 is connected to the operation device 105, the display device 106, the medium sensor 111, the imaging device 116, the driving source 131, the interface device 132, the storage device 140, etc., and controls each of these components. The processing circuit 150 performs driving control of the driving source 131, image capture control of the imaging device 116, etc., acquires an input image, and transmits it to the information processing device via the interface device 132.

[0047] FIG. 5 is a diagram showing a schematic configuration of a storage device and a processing circuit according to an embodiment.

[0048] 5, the storage device 140 stores a control program 141, a setting program 142, an image processing program 143, etc. Each of these programs is a functional module implemented by software that runs on a processor. The processing circuit 150 reads each program stored in the storage device 140 and operates according to the read programs, thereby functioning as a control unit 151, a setting unit 152, and an image processing unit 153.

[0049] FIG. 6 is a schematic diagram illustrating an example of a data structure of the setting table.

[0050] The setting table specifies the operation settings of the light emitting device 121, the line sensor 122, the driving source 131, etc., when the imaging device 116 reads a medium and generates read image data. As shown in Fig. 6, the setting table stores in advance the resolution, reading interval, exposure time, movement speed, etc. of the read image data in association with each other for each combination of the resolution of the output image data and the reading mode.

[0051] The output image data is an example of image data output by an image processing unit described later. The output image data is image data output from the image reading device 100. The reading mode is an operation mode of the image reading device 100 for generating output image data of each resolution. The reading mode includes, for example, a normal mode and a moire suppression mode. The normal mode is an example of a second mode, and the moire suppression mode is an example of a first mode. In the normal mode, the line sensor 122 reads the medium at the same resolution as the resolution of the output image data. The moire suppression mode is a mode for suppressing the occurrence of moire in the output image data. In the moire suppression mode, the line sensor 122 reads the medium at a higher resolution than the resolution of the output image data. In the moire suppression mode, the line sensor 122 reads the medium in the sub-scanning direction (medium conveying direction A1) at a higher resolution than the resolution of the output image data, and reads the medium in the main scanning direction (width direction A2) at the same resolution as the resolution of the output image data. In the moire suppression mode, the line sensor 122 may read the medium at a resolution higher than the resolution of the output image data, even in the main scanning direction. The reading mode may not be set commonly for all resolutions, but may be set individually for each resolution. For example, when the resolution of the output image data is 600 dpi, the reading mode may be fixed to the normal mode, and when the resolution of the output image data is 300 dpi, the reading mode may be fixed to the moire suppression mode.

[0052] The read image data is image data generated by the line sensor 122 reading the medium. The read interval is the interval in the sub-scanning direction between each line read by the line sensor 122 on the medium. The exposure time is the exposure time per line in the medium, and is the time that the light emitting device 121 irradiates light onto one line in the medium. The moving speed is the relative moving speed of the medium with respect to the imaging device 116. In this embodiment, the moving speed is the moving speed of the medium conveyed by the conveying unit. As the moving speed, for example, the circumferential speeds of the feed roller 112, the separation roller 113, the first conveying roller 114, the second conveying roller 115, the third conveying roller 117, and the fourth conveying roller 118 are set. Instead of the moving speed, the rotation speed or the driving interval of each motor for rotating each roller included in the driving source 131 may be set.

[0053] The settings of the resolution of the read image data, the read interval, the exposure time, and the movement speed will be described below.

[0054] The resolution of the read image data in the normal mode is set to the same resolution as the resolution of the output image data. On the other hand, the resolution of the read image data in the moiré suppression mode is set to a resolution higher than the resolution of the output image data. The resolution of the read image data in the moiré suppression mode is set to a resolution higher than the resolution of the output image data in the sub-scanning direction, and is set to the same resolution as the resolution of the output image data in the main scanning direction. The resolution of the read image data in the moiré suppression mode may be set to a resolution higher than the resolution of the output image data in the main scanning direction.

[0055] FIG. 7 is a schematic diagram for explaining the color of light irradiated by a light emitting device according to an embodiment onto a medium being transported.

[0056] In FIG. 7, the vertical direction indicates the sub-scanning direction (medium transport direction A1), and the horizontal direction indicates the main scanning direction (width direction A2). Medium M1 indicates a medium on which output image data of a first resolution is generated in normal mode. Medium M2 indicates a medium on which output image data of a second resolution is generated in normal mode. Medium M3 indicates a medium on which output image data of a second resolution is generated in moire suppression mode. The second resolution is lower than the first resolution. FIG. 7 shows an example in which the second resolution is 1 / 2 the first resolution. For example, the first resolution is 600 dpi (dots per inch) and the second resolution is 300 dpi.

[0057] The color of the light emitted by the light emitting device 121 is switched as each medium moves, and thus the color of the light emitted by the light emitting device 121 is switched for each position in the medium in the sub-scanning direction.

[0058] In the example shown in FIG. 7, the reading interval (i.e., the length per line in the sub-scanning direction) in the case where the medium is read at a first resolution in the sub-scanning direction (i.e., when the resolution of the read image data is the first resolution) is set to a first interval D. In this case, on a medium M1 for which output image data of the first resolution is generated in normal mode, the color of light (red, green, blue) emitted by the light-emitting device 121 is switched every time the medium moves a distance D / 3, which is 1 / 3 of the first interval D, in the sub-scanning direction. As a result, an area R on the medium M1 that is illuminated with red, green, and blue lights, respectively, is switched. R , R G , R B The length in the sub-scanning direction is D / 3.

[0059] On the other hand, when the medium is read in the sub-scanning direction at a second resolution that is half the first resolution (i.e., when the resolution of the read image data is the second resolution), the read interval is a second interval 2D that is twice the first interval D. In the medium M2 for which output image data of the second resolution is generated in the normal mode, the color of light irradiated by the light emitting device 121 is switched every time the medium moves a distance 2D / 3, which is 1 / 3 of the second interval 2D, in the sub-scanning direction. As a result, an area R on the medium M2 that is irradiated with red, green, and blue colors is formed. R , R G , R B The length in the sub-scanning direction is 2D / 3.

[0060] In the example shown in FIG. 7, the resolution for reading the medium in the moiré suppression mode in the sub-scanning direction (i.e., the resolution of the read image data) is twice the resolution for reading the medium in the normal mode. In this case, in order to generate output image data with a second resolution in the moiré suppression mode in the sub-scanning direction, the medium needs to be read at the first resolution, which is twice the resolution of the second resolution, and the reading interval is the first interval D. Therefore, in the medium M3 on which output image data with the second resolution is generated in the moiré suppression mode, the color of light irradiated by the light emitting device 121 is switched every time the medium moves a distance D / 3, which is 1 / 3 of the first interval D, in the sub-scanning direction. As a result, an area R on the medium M3 that is irradiated with red, green, and blue colors is formed. R , R G , R B The length in the sub-scanning direction is D / 3.

[0061] FIG. 8 is a schematic diagram for explaining a control signal that defines the emission timing of light of each color by a light emitting device according to an embodiment.

[0062] In FIG. 8, the horizontal axis indicates time, and the vertical axis indicates the signal value (ON / OFF). R is a control signal input to the red light emitting device 124, and signal S G is a control signal input to the green light emitting device 125, and signal S Bare control signals input to blue light emitting device 126. Light emitting device 121 emits light of the corresponding color at the timing when the signal value of each control signal is ON.

[0063] 8, the exposure time that can ensure sufficient amounts of red, green, and blue light to read one line in the sub-scanning direction when reading a medium at a first resolution in normal mode is set to the first exposure time T. In this case, the color of light (red, green, blue) emitted by the light emitting device 121 is switched every time T / 3, which is 1 / 3 of the first exposure time T.

[0064] On the other hand, when the medium is read at the second resolution, the resolution in the main scanning direction may be 1 / 2 of the first resolution. Therefore, the image reading device 100 can generate an electrical signal for one pixel of the second resolution by synthesizing electrical signals output from two-pixel imaging elements at the first resolution in the main scanning direction. The total amount of light obtained at each pixel is the value obtained by multiplying the sensor area by the exposure time. Therefore, the image reading device 100 can obtain the amount of light required to image one pixel in half the normal exposure time by obtaining an electrical signal for one pixel using two-pixel imaging elements in the main scanning direction. Therefore, the exposure time that can ensure sufficient amounts of red, green, and blue light to read one line when reading a medium at the second resolution in the sub-scanning direction in the normal mode is the second exposure time T / 2, which is 1 / 2 of the first exposure time T. In this case, the color of light (red, green, blue) emitted by the light emitting device 121 is switched every time T / 6, which is ⅓ of the second exposure time T / 2.

[0065] In the example shown in FIG. 8, the resolution for reading the medium in the moiré suppression mode is twice the resolution for reading the medium in the normal mode in the sub-scanning direction, and is the same as the resolution for reading the medium in the normal mode in the main scanning direction. Considering the user's work efficiency, it is desirable that the time required to read the entire medium in the second resolution in the moiré suppression mode is the same as the time required to read the entire medium in the second resolution in the normal mode. Therefore, when generating output image data with the second resolution in the moiré suppression mode, that is, when reading the medium in the first resolution in the sub-scanning direction in the moiré suppression mode, the exposure time per line required is the third exposure time T / 4, which is 1 / 2 of the second exposure time T / 2. In this case, the color of light (red, green, blue) emitted by the light emitting device 121 is switched every time T / 12, which is 1 / 3 of the third exposure time T / 4.

[0066] When generating output image data of the second resolution in the moiré suppression mode, the image reading device 100 can use an image sensor of two pixels of the first resolution to capture one pixel of the second resolution in the main scanning direction, as in the normal mode. However, the number of lines read when generating output image data of the second resolution in the moiré suppression mode is twice the number of lines read when generating output image data of the second resolution in the normal mode. Therefore, sufficient exposure time is not ensured for the line sensor 122 to read each line. Therefore, in the process described below, the image reading device 100 corrects the image so that the luminance value of each pixel in the image is approximately the same as the luminance value when sufficient exposure time is ensured. Note that in the moiré suppression mode, when the line sensor 122 reads the medium at the first resolution in the main scanning direction, the exposure time per line may be the third exposure time T / 4. In this case, since the image reading device 100 cannot utilize the two-pixel image sensor of the first resolution, in the process described below, the image is corrected so that the luminance value of each pixel in the image is approximately the same as the luminance value when sufficient exposure time is secured.

[0067] 7 and 8, for a first setting in which the resolution of the output image data is set to the first resolution and the reading mode is set to the normal mode, the resolution of the read image data is set to the first resolution. Also, for the first setting, the reading interval is set to a first interval D, the exposure time per line is set to a first exposure time T, and the moving speed is set to a first moving speed D / T obtained by dividing the first interval D by the first exposure time T.

[0068] Also, for the second setting in which the resolution of the output image data is set to the second resolution and the reading mode is set to the normal mode, the resolution of the read image data is set to the second resolution. Also, for the second setting, the reading interval is set to the second interval 2D, the exposure time per line is set to the second exposure time T / 2, and the moving speed is set to the second moving speed 4D / T obtained by dividing the second interval 2D by the second exposure time T / 2. That is, the reading interval in the second setting is set to twice the reading interval in the first setting. The exposure time in the second setting is set to 1 / 2 the exposure time in the first setting. The moving speed in the second setting is set to four times the moving speed in the first setting.

[0069] In addition, for the third setting in which the resolution of the output image data is set to the second resolution and the reading mode is set to the moire suppression mode, the resolution in the sub-scanning direction of the read image data is set to the first resolution, and the resolution in the main scanning direction is set to the second resolution. In addition, for the third setting, the reading interval is set to the first interval D, the exposure time is set to the third exposure time T / 4, and the moving speed is set to the second moving speed 4D / T obtained by dividing the first interval D by the third exposure time T / 4. That is, the reading interval in the third setting is set to the same as the reading interval in the first setting and is set to 1 / 2 of the reading interval in the second setting. The exposure time in the third setting is set to 1 / 4 of the exposure time in the first setting and is set to 1 / 2 of the exposure time in the second setting. The moving speed in the third setting is set to 4 times the moving speed in the first setting and is set to the same as the moving speed in the second setting.

[0070] 7 and 8 are merely examples, and the first resolution and the second resolution may be set in any way as long as the second resolution is higher than the first resolution. In either case, when the reading mode is the same, the reading interval when the resolution of the output image data is low is set to a value larger than the reading interval when the resolution of the output image data is high. Also, when the reading mode is the same, the exposure time per line when the resolution of the output image data is low is set to a time shorter than the exposure time per line when the resolution of the output image data is high. Also, when the reading mode is the same, the movement speed when the resolution of the output image data is low is set to a speed higher than the movement speed when the resolution of the output image data is high.

[0071] In addition, when the resolution of the output image data is the same, the reading interval when the reading mode is the moire suppression mode is set to a value smaller than the reading interval when the reading mode is the normal mode. In addition, when the resolution of the output image data is the same, the exposure time per line when the reading mode is the moire suppression mode is set to a time shorter than the exposure time per line when the reading mode is the normal mode. In addition, when the resolution of the output image data is the same, the movement speed when the reading mode is the moire suppression mode may be set to the same as the movement speed when the reading mode is the normal mode.

[0072] FIG. 9 is a flowchart showing an example of the operation of the medium reading process.

[0073] An example of the operation of the medium reading process of the image reading device 100 will be described below with reference to the flowchart shown in Fig. 9. Note that the flow of the operation described below is executed mainly by the processing circuit 150 in cooperation with each element of the image reading device 100 based on a program stored in advance in the storage device 140.

[0074] First, the control unit 151 waits until a user inputs an instruction to read a medium using the operation device 105 or an information processing device, and an operation signal instructing the user to read a medium is received from the operation device 105 or the interface device 132 (step S101).

[0075] The operation signal may include job information specified by the user. The job information is a setting related to the image reading process. The job information includes settings such as the type of medium (paper / card / business card / photo, etc.), color setting of the output image data (color / grayscale / black and white, etc.), resolution (200 dpi / 300 dpi / 600 dpi, etc.), reading side (double-sided / single-sided), or reading mode.

[0076] Next, control unit 151 acquires a medium signal from medium sensor 111, and determines whether or not a medium is placed on mounting table 103 based on the acquired medium signal (step S102). If no medium is placed on mounting table 103, control unit 151 ends the series of steps.

[0077] On the other hand, when a medium is placed on the placement table 103, the setting unit 152 sets the resolution and reading mode of the output image data (step S103). The setting unit 152 identifies the resolution and reading mode of the output image data from, for example, the job information included in the operation signal, and sets (stores) them in the storage device 140. Note that the job information may not be included in the operation signal, but may be set by the user using the operation device 105 or an information processing device before the operation signal is transmitted, and may be stored in the storage device 140 in advance.

[0078] 7 and 8 as the resolution of the output image data, and can set the normal mode and the moire suppression mode as the reading mode. This allows the user to obtain output image data having the desired resolution that is generated according to the desired reading mode.

[0079] The initial reading mode may be set to the moiré suppression mode, so that the image reading device 100 can generate output image data in the moiré suppression mode that can suppress the occurrence of moiré when the reading mode is not set by the user.

[0080] Next, the setting unit 152 sets the resolution of the read image data (step S104). The setting unit 152 refers to the setting table and specifies the resolution of the read image data corresponding to the resolution of the output image data and the reading mode set in step S103. The setting unit 152 sets the specified resolution in the imaging device 116 so that the medium is read at the specified resolution.

[0081] Next, the setting unit 152 sets the exposure time (step S105). The setting unit 152 refers to the setting table and specifies the exposure time corresponding to the resolution of the output image data and the reading mode set in step S103. The setting unit 152 sets the specified exposure time in the imaging device 116 so that the color of the light irradiated to the medium is switched according to the specified exposure time and the medium is read.

[0082] Next, the setting unit 152 sets the moving speed (step S106). The setting unit 152 refers to the setting table and specifies the moving speed corresponding to the resolution of the output image data and the reading mode set in step S103. The setting unit 152 sets the rotation speed or the drive interval, etc. according to the specified moving speed for each motor of the drive source 131 so that the medium moves (is transported) at the specified moving speed.

[0083] Next, the control unit 151 drives the driving source 131 to rotate each roller to feed and transport the medium (step S107), whereby the transport unit transports the medium at the movement speed set in step S106.

[0084] When a first resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the control unit 151 moves the medium at a first moving speed. On the other hand, when a second resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the control unit 151 moves the medium at a second moving speed higher than the first moving speed. Also, when a second resolution is set as the resolution of the output image data and the moire suppression mode is set as the reading mode, the control unit 151 moves the medium at a second moving speed higher than the first moving speed. In this way, the image reading device 100 can reduce the reading time when reading a medium at the second resolution, thereby improving the work efficiency of the user.

[0085] Next, the image processing unit 153 causes the imaging device 116 to capture an image of the medium, and acquires read image data from the imaging device 116 (step S108). As a result, the imaging device 116 reads the medium at the resolution set in step S104 while irradiating the medium with light of each color according to the exposure time set in step S105, thereby reading the medium at the corresponding reading interval and generating read image data of that resolution.

[0086] When a first resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the imaging device 116 reads the medium at the first resolution and generates read image data at the first resolution. On the other hand, when a second resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the imaging device 116 reads the medium at the second resolution and generates read image data at the second resolution. Also, when a second resolution is set as the resolution of the output image data and the moire suppression mode is set as the reading mode, the imaging device 116 reads the medium at the first resolution and generates read image data at the first resolution.

[0087] In the moire suppression mode, the image reading device 100 can reduce the length of one line in the sub-scanning direction to be read by reading the medium at a resolution higher than the resolution of the output image data. For example, if the size of each printed dot printed on the medium is smaller than the second interval 2D shown in FIG. 7, when the medium is read at the second resolution in the normal mode, each printed dot passes the imaging position before being irradiated with all the colors of red, green, and blue. In this case, color unevenness occurs in the read image data and the output image data. Then, moire occurs due to the color unevenness occurring periodically in the read image data and the output image data.

[0088] On the other hand, if the size of each printed dot printed on the medium is smaller than the second interval 2D but equal to or larger than the first interval D, when the medium is read at the first resolution in the moiré suppression mode, each printed dot is reliably irradiated with light of all colors, red, green, and blue. Therefore, in the moiré suppression mode, the image reading device 100 can suppress the occurrence of color unevenness in the output image data by reading the medium at a resolution higher than the resolution of the output image data, and as a result, can suppress the occurrence of moiré in the output image data.

[0089] In order to prevent the occurrence of moire, it is necessary to read the medium at a resolution that is at least twice the print resolution (output line number) of the medium. For example, when the resolution when reading the medium is 300 dpi, moire is likely to occur when reading a medium with an output line number of about 150 lines. Also, when the resolution when reading the medium is 600 dpi, moire is likely to occur when reading a medium with an output line number of about 300 lines. However, the print resolution (output line number) of a general medium is often 200 lines or less. Therefore, when the resolution of the output image data is 300 dpi, the image reading device 100 is likely to be able to prevent the occurrence of moire in the output image data by reading the medium at a resolution of 600 dpi in the moire suppression mode. That is, when the first resolution is 600 dpi, the image reading device 100 is likely to be able to prevent the occurrence of moire in the output image data.

[0090] Also, when the first resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the imaging device 116 reads the medium at a first interval in the sub-scanning direction. On the other hand, when the second resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the imaging device 116 reads the medium at a second interval in the sub-scanning direction that is larger than the first interval. Also, when the second resolution is set as the resolution of the output image data and the moire suppression mode is set as the reading mode, the imaging device 116 reads the medium at a first interval in the sub-scanning direction. That is, the image reading device 100 sets the reading interval when reading the medium at the second resolution in the moire suppression mode to be the same as the reading interval when reading the medium at the first resolution in the normal mode. The image reading device 100 can suppress the occurrence of moire in the output image data by reducing the length in the sub-scanning direction of one line read in the moire suppression mode.

[0091] Also, when the first resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the image capture device 116 sets the exposure time per line to the first exposure time. On the other hand, when the second resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the image capture device 116 sets the exposure time per line to the second exposure time, which is shorter than the first exposure time. Also, when the second resolution is set as the resolution of the output image data and the moire suppression mode is set as the reading mode, the image capture device 116 sets the exposure time per line to the third exposure time, which is shorter than the second exposure time. That is, the image reading device 100 sets the exposure time when reading a medium at the first resolution in the moire suppression mode to be shorter than the exposure time when reading a medium at the second resolution in the normal mode. As a result, the image reading device 100 can reduce the reading time when reading a medium in the moire suppression mode, thereby improving the work efficiency of the user.

[0092] Also, when the first resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the imaging device 116 sets the exposure time per line to the first exposure time. That is, in this case, the imaging device 116 reads the medium under the first exposure condition in which the exposure time per line is the first exposure time. On the other hand, when the second resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the imaging device 116 sets the exposure time per line to the second exposure time that is shorter than the first exposure time. That is, in this case, the imaging device 116 reads the medium under the second exposure condition in which the exposure time per line is the second exposure time. Also, when the second resolution is set as the resolution of the output image data and the moire suppression mode is set as the reading mode, the imaging device 116 sets the exposure time per line to the third exposure time that is even shorter than the second exposure time. That is, in this case, the imaging device 116 reads the medium under the third exposure condition in which the exposure time per line is the third exposure time.

[0093] In this way, the image reading device 100 makes the exposure time when reading a medium at the first resolution in the moiré suppression mode shorter than the exposure time when the second resolution is set as the resolution of the output image data in the normal mode and the medium is read at the second resolution. This allows the image reading device 100 to reduce the reading time when reading a medium in the moiré suppression mode, thereby improving the user's work efficiency.

[0094] Furthermore, the image reading device 100 sets the exposure time when the second resolution is set as the resolution of the output image data and the medium is read at the first resolution to be shorter than the exposure time when the first resolution is set as the resolution of the output image data and the medium is read at the first resolution. Furthermore, the image reading device 100 sets the exposure time when the second resolution is set as the resolution of the output image data and the medium is read at the second resolution to be shorter than the exposure time when the first resolution is set as the resolution of the output image data and the medium is read at the first resolution. This allows the image reading device 100 to reduce the reading time when reading a medium at the second resolution, thereby improving the work efficiency of the user.

[0095] Next, the image processing unit 153 generates output image data based on the acquired read image data (step S109). If the normal mode is set as the reading mode, the image processing unit 153 does not correct the read image data, but uses it as it is as output image data.

[0096] On the other hand, when the moire suppression mode is set as the reading mode, the image processing unit 153 converts the resolution of the acquired read image data to the resolution of the output image data set in step S103. As described above, in the moire suppression mode, the imaging device 116 reads the medium at a resolution higher than the resolution of the output image data to generate the read image data. The image processing unit 153 reduces the read image data (thinning out pixels in the read image data) using a known image processing technique such as nearest neighbor interpolation or linear interpolation, and converts the resolution of the read image data to the resolution of the output image data. The image processing unit 153 corrects the read image data so that the number of lines in the output image data is less than the number of lines in the read image data to generate the output image data. Note that in the moire suppression mode, when the line sensor 122 reads the medium at a resolution higher than the resolution of the output image data in the main scanning direction, the image processing unit 153 thins out pixels in the read image data in the main scanning direction as well to generate the output image data.

[0097] That is, when the first resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the image processing unit 153 does not correct the read image data and outputs the read image data as it is. When the second resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the image processing unit 153 does not correct the read image data and outputs the read image data as it is. This allows the image reading device 100 to appropriately generate output image data having a resolution designated by the user. On the other hand, when the second resolution is set as the resolution of the output image data and the moire suppression mode is set as the reading mode, the image processing unit 153 converts the image data of the first resolution into image data of a second resolution lower than the first resolution. This allows the image reading device 100 to generate output image data of the second resolution in which the occurrence of moire is suppressed.

[0098] Furthermore, when the moire suppression mode is set as the reading mode, the image processing unit 153 corrects the luminance of each pixel in the read image data. As described above, when the read image data is generated in the moire suppression mode, sufficient exposure time is not ensured for the line sensor 122 to read each line. The image processing unit 153 uses a known image processing technique such as a product-sum operation in which the luminance value of each pixel is multiplied by a predetermined coefficient and / or a predetermined offset is added, or gamma correction, to correct the luminance value of each pixel in the read image data so that the luminance value of each pixel in the read image data is approximately the same as the luminance value when sufficient exposure time is ensured. For example, the image processing unit 153 corrects the luminance value of each pixel so that the maximum and minimum values ​​of the luminance value of each pixel are approximately the same when sufficient exposure time is ensured and when sufficient exposure time is not ensured. The image processing unit 153 corrects the read image data to generate output image data so that the luminance value of each pixel in the output image data is higher than the luminance value of each pixel in the read image data.

[0099] That is, when the second resolution is set as the resolution of the output image data and the moire suppression mode is set as the reading mode, the image processing unit 153 further corrects the luminance of the read image data, so that the image reading device 100 can generate output image data having appropriate luminance while suppressing an increase in the reading time when reading a medium in the moire suppression mode.

[0100] Furthermore, when the exposure time is shortened, there is a possibility that noise occurring in the read image data increases. Therefore, when the moire suppression mode is set as the reading mode, the image processing unit 153 may apply a known noise removal filter such as a smoothing filter to the read image data to remove noise in the read image data.

[0101] Next, the image processing unit 153 outputs the generated output image data by transmitting it to the information processing device via the interface device 132, or by displaying it on the display device 106 (step S110).

[0102] Next, control unit 151 determines whether or not a medium remains on mounting table 103 based on the medium signal received from medium sensor 111 (step S111). If a medium remains on mounting table 103, control unit 151 returns the process to step S108, and repeats the processes of steps S108 to S111.

[0103] On the other hand, if there are no media remaining on the mounting table 103, the control unit 151 controls the driving source 131 to stop each roller (step S112), and ends the series of steps.

[0104] As described above in detail, the image reading device 100 shortens the exposure time, reads the medium at high resolution, and converts the generated image data to low resolution. This makes it possible for the image reading device 100 to suppress the occurrence of moire in the generated image data while suppressing an increase in the medium reading time.

[0105] Furthermore, the image reading device 100 can suppress the occurrence of moire in the read image data without reducing the resolution or color reproducibility. Furthermore, since the image reading device 100 can suppress the occurrence of moire in the read image data, it is not necessary to execute a filter process such as a smoothing filter to reduce moire, and the entire output image data can be suppressed from becoming blurred. As a result, the image reading device 100 can suppress a decrease in the character recognition rate in OCR (Optical Character Reader) processing.

[0106] In addition, because a CIS is low-cost but has high resolution, it is highly likely to clearly read the halftone dots printed on the medium, causing moire in the read image data. Image reading device 100 can suppress the occurrence of moire in the read image data, so a low-cost CIS can be used as line sensor 122, and the cost of the device can be reduced.

[0107] In addition, while a one-line monochrome sensor is less expensive than a three-line color sensor, there is a high possibility that moire will occur in the read image data due to misalignment of the positions where the light of each color is irradiated within the medium. Since the image reading device 100 can suppress the occurrence of moire in the read image data, a low-cost one-line monochrome sensor can be used as the line sensor 122, and the device cost can be reduced.

[0108] 10A and 10B are diagrams illustrating an example of a configuration of an image reading device according to another embodiment. Fig. 10A is a perspective view of the image reading device 200 with the cover 202 open, and Fig. 10B is a perspective view of the image reading device 200 with the cover 202 closed.

[0109] 10A and 10B, the image reading device 200 is, for example, a flatbed type scanner device, etc. The image reading device 200 has a housing 201, a cover 202, etc.

[0110] The housing 201 has a glass plate 203 and the like. The glass plate 203 is a member on which a medium is placed, and is provided on the upper surface of the housing 201. The glass plate 203 forms a surface on which the medium is placed.

[0111] The cover 202 has a backing member 204 and the like. The cover 202 is provided so as to be openable and closable with respect to the housing 201. When the cover 202 is open, a medium can be placed on the glass plate 203 of the housing 201, and when the cover 202 is closed, the backing member 204 faces an imaging device provided below the glass plate 203 (inside the housing 201). The surface of the backing member 204 facing the imaging device has a white color, similar to the first backing member 123a, and the image reading device 200 performs image correction such as shading based on an image signal captured by the backing member 204.

[0112] Fig. 11 is a cross-sectional view of an image reading device according to another embodiment of the present invention, taken along line AA' in Fig. 10(A) of the image reading device 200 with the cover 202 closed.

[0113] 11, the housing 201 has an imaging device 205. The imaging device 205 is provided at a position facing a backing member 204 provided on the cover 202 in a closed state, sandwiching the glass plate 203 therebetween. The imaging device 205 extends in parallel with the glass plate 203 and in a direction perpendicular to the direction of the arrow A10 (main scanning direction) so as to be able to capture an image from one end of the glass plate 203 to the other end. The imaging device 205 is also provided movably along the direction of the arrow A10 (sub-scanning direction) so as to be able to capture an image from one end of the glass plate 203 to the other end.

[0114] The imaging device 205 is an example of a reading unit, and generates read image data by reading a medium placed on the glass plate 203. The imaging device 205 includes a light emitting device 206, a line sensor 207, and the like.

[0115] The light emitting device 206 has a structure similar to that of the first light emitting device 121a. The light emitting device 206 irradiates red, green, and blue light onto a medium placed on the glass plate 203. The line sensor 207 has a structure similar to that of the first line sensor 122a. The imaging device 205 also has a lens that forms an image on an imaging element, and an A / D converter that amplifies and analog-to-digital (A / D) converts an electrical signal output from the imaging element. The line sensor 207 reads the medium placed on the glass plate 203 line by line, and generates read image data.

[0116] Image reading device 200 has the same components as image reading device 100 shown in Fig. 4. However, image reading device 200 has imaging device 205 instead of imaging device 116. In image reading device 200, driving source 131 is provided so as to move imaging device 205 via a moving mechanism such as a pulley, a belt, a gear, a rack, and a pinion, rather than rotating a roller for transporting a medium.

[0117] FIG. 12 is a flowchart showing an example of the operation of the medium reading process according to the present embodiment.

[0118] An example of the operation of the medium reading process of the image reading device 200 will be described below with reference to the flowchart shown in Fig. 12. Note that the flow of the operation described below is executed mainly by the processing circuit 150 in cooperation with each element of the image reading device 200 based on a program stored in advance in the storage device 140.

[0119] The processes in steps S201, S202 to S204, and S207 to S209 in Fig. 12 are similar to the processes in steps S101, S103 to S105, and S108 to S110 in Fig. 9, and therefore will not be described below. Only the processes in steps S205, S206, and S210 will be described below.

[0120] In step S205, the setting unit 152 sets the moving speed (step S205). In this embodiment, the moving speed is the relative moving speed of the medium with respect to the imaging device 205, and the moving speed of the imaging device 205 is set in the setting table as the moving speed. Instead of the moving speed, the rotation speed or driving interval of a motor included in the driving source 131 for moving the imaging device 205 may be set. The setting unit 152 refers to the setting table and specifies the moving speed corresponding to the resolution of the output image data and the reading mode set in step S202. The setting unit 152 sets the rotation speed or driving interval according to the specified moving speed to each motor of the driving source 131 so that the imaging device 205 moves at the specified moving speed.

[0121] In step S206, the control unit 151 drives the driving source 131 to move the imaging device 205 (step S206), whereby the imaging device 205 moves at the movement speed set in step S205.

[0122] When a first resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the control unit 151 moves the imaging device 205 at a first moving speed. On the other hand, when a second resolution is set as the resolution of the output image data and the normal mode is set as the reading mode, the control unit 151 moves the imaging device 205 at a second moving speed higher than the first moving speed. Also, when a second resolution is set as the resolution of the output image data and the moire suppression mode is set as the reading mode, the control unit 151 moves the imaging device 205 at a second moving speed higher than the first moving speed. This allows the image reading device 200 to reduce the reading time when reading a medium at the second resolution, thereby improving the user's work efficiency.

[0123] In step S210, the control unit 151 controls the driving source 131 to stop the imaging device 205 (step S210), and ends the series of steps. Note that the control unit 151 may stop the imaging device 205 at the timing when the input image is acquired in step S207.

[0124] As described above in detail, the image reading device 200 is capable of suppressing the occurrence of moire in the generated image data while preventing an increase in the medium reading time, even when the imaging device 205 is moved to read the medium.

[0125] FIG. 13 is a diagram showing a schematic configuration of a processing circuit of an image reading device according to still another embodiment.

[0126] The processing circuit 350 is used in place of the processing circuit 150 of the image reading device 100 or the image reading device 200, and executes the medium reading process and the like in place of the processing circuit 150. The processing circuit 350 has a control circuit 351, a setting circuit 352, an image processing circuit 353, and the like. Note that each of these units may be composed of an independent integrated circuit, microprocessor, firmware, and the like.

[0127] The control circuit 351 is an example of a control unit, and has the same functions as the control unit 151. The control circuit 351 receives an operation signal from the operation device 105 or the interface device 132, and a medium signal from the medium sensor 111. The control circuit 351 outputs the resolution and reading mode of the output image data contained in the operation signal to the setting circuit 352. The control circuit 351 also controls the drive source 131 based on each piece of information received or read.

[0128] The setting circuit 352 is an example of a setting unit, and has the same function as the setting unit 152. The setting circuit 352 receives the resolution and reading mode of the output image data from the control circuit 351, and sets them in the storage device 140. The setting circuit 352 also reads a setting table from the storage device 140, and sets the imaging device 116 or 205 and the driving source 131 based on each piece of information received or read.

[0129] The image processing circuit 353 is an example of an image processing unit, and has the same function as the image processing unit 153. The image processing circuit 353 acquires read image data from the imaging device 116, generates output image data based on the read image data, and outputs the output image data to the interface device 132.

[0130] As described above in detail, even when the processing circuit 350 is used, the image reading device 100 is able to suppress the occurrence of moire in the generated image data while preventing an increase in the medium reading time.

[0131] Although the preferred embodiments have been described above, the embodiments are not limited to these. For example, a separation pad may be used instead of the separation roller 113. The image reading device 100 may also have a so-called U-turn path, and may feed and transport the media placed on the placement table in order from the top, and discharge the media onto the discharge table. [Explanation of symbols]

[0132] 100 Image reading device, 116 Imaging device, 151 Control unit, 152 Setting unit, 153 Image processing unit

Claims

1. a reading unit including a line sensor that reads the reading object line by line, reading the reading object at a first resolution and generating image data at the first resolution; an image processing unit that converts the image data of the first resolution into image data of a second resolution lower than the first resolution and outputs the image data; the reading unit sets an exposure time per line when reading the object at the first resolution to be shorter than the exposure time when reading the object at the second resolution; 1. An image reading apparatus comprising:

2. Further comprising a setting unit capable of setting a resolution, 2. The image reading device according to claim 1, wherein when the second resolution is set, the reading unit generates image data of the first resolution, and the image processing unit converts the image data of the first resolution into image data of the second resolution.

3. When the first resolution is set, the reading unit generates image data of the first resolution, The image reading device according to claim 2 , wherein the reading section sets the exposure time when the second resolution is set to be shorter than the exposure time when the first resolution is set.

4. Further comprising a control unit for moving a reading object or the reading unit, 3. The image reading device of claim 2, wherein the control unit moves the object to be read or the reading unit at a first movement speed when the first resolution is set, and moves the object to be read or the reading unit at a second movement speed higher than the first movement speed when the second resolution is set.

5. Further comprising a control unit for moving a reading object or the reading unit, 3. The image reading device according to claim 2, wherein the reading unit reads the object at a first interval in the sub-scanning direction when the first resolution is set, and reads the object at the first interval in the sub-scanning direction when the second resolution is set.

6. When the second resolution is set in the first mode, the reading unit generates image data of the first resolution, and the image processing unit converts the image data of the first resolution into image data of the second resolution; The image reading device according to claim 2 , wherein when the second resolution is set in the second mode, the reading unit generates image data at the second resolution.

7. 3. The image reading device according to claim 1, wherein the image processing section converts the image data of the first resolution into image data of the second resolution and corrects brightness.

8. a reading unit including a line sensor that reads the object line by line, converting image data of a first resolution generated by reading the object at a first resolution into image data of a second resolution lower than the first resolution, and outputting the image data; the reading unit sets an exposure time per line when reading the object at the first resolution to be shorter than the exposure time when reading the object at the second resolution; 13. An image reading method comprising:

9. A method for controlling an image reading device having a reading unit including a line sensor that reads an object line by line, and that reads the object at a first resolution and generates image data of the first resolution, comprising: causing the image reading device to convert the image data of the first resolution into image data of a second resolution lower than the first resolution and output the image data; the reading unit sets an exposure time per line when reading the object at the first resolution to be shorter than the exposure time when reading the object at the second resolution; A control program comprising:

Images