Image reading device and image formation apparatus

Abstract

To provide an image reading device and an image formation apparatus capable of reducing deviation between a center position for reading of a light source in a visible light region and a center position for reading of a light source in an invisible region, and thereby reducing loss of an image in the visible light region.SOLUTION: An image reading device for reading an original comprises: a light source unit including a first light source that irradiates red light onto the original, a second light source that irradiates green light, a third light source that irradiates blue light, and a fourth light source that irradiates light in an invisible region; a sensor that reads reflected light of the light irradiated onto the original; a signal processing unit that performs A / D conversion of an image signal read by the sensor and outputs image data; and a control unit that controls switching between a normal reading mode and a special reading mode as reading modes and controls operation of the light source unit. In the special reading mode, deviation between center positions for reading of the first light source, the second light source and the third light source and a center position for reading of the fourth light source is reduced as compared with the normal reading mode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image reading device and an image forming device. [Background technology]

[0002] Image reading devices that scan images typically read images in the visible light range, which is the wavelength range of visible light. However, image reading devices that read patterns or characters in the invisible range, which is outside the visible light range, are also known. One known method for reading such invisible images is to pass light outside the invisible range through a spectral filter, disperse it, and receive it with a sensor to extract image data in the invisible range. This method requires a spectral optical system, such as a filter, and a signal processing system, such as a light receiving element and an A / D converter, for each color to be dispersed, resulting in a problem of expensive and large equipment. A known solution to this problem is to sequentially pulse multiple light sources onto the document to extract image data. This eliminates the need for a spectral optical system, such as a filter, and consolidates the signal processing system, such as a light receiving element and an A / D converter, while maintaining the same accuracy as previous methods, resulting in a device with a simpler and more inexpensive structure.

[0003] As a technique for reading an image using such a plurality of light sources, a configuration has been disclosed in which a plurality of LEDs (Light Emitting Diodes) are used and light is selectively emitted in pulses from these LEDs (for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology described in Patent Document 1, the central position of the light source for reading the visible light region within one line is misaligned from the central position of the light source for reading the invisible light region, which causes a problem in that the image in the visible light region cannot be acquired and is lost while reading the image from the light source for the invisible light region.

[0005] The present invention has been made in consideration of the above, and aims to provide an image reading device and an image forming device that can reduce the deviation between the center position of reading with a light source in the visible light range and the center position of reading with a light source in the invisible light range, thereby reducing image loss in the visible light range. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention provides an image reading device for reading an original, comprising: a light source unit having a first light source that irradiates the original with red light, a second light source that irradiates green light, a third light source that irradiates blue light, and a fourth light source that irradiates light in the invisible range; a sensor that reads the reflected light of the light irradiated onto the original from the light source unit; a signal processing unit that performs A / D conversion on the image signal read by the sensor and outputs image data; and a control unit that controls the reading mode of the image reading device to be switchable between a normal reading mode and a special reading mode and controls the operation of the light source unit, wherein in the special reading mode, the deviation between the central position of reading of the first light source, the second light source, and the third light source and the central position of reading of the fourth light source is reduced more than in the normal reading mode. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce the deviation between the center position of reading with a light source in the visible light range and the center position of reading with a light source in the invisible light range, thereby reducing image loss in the visible light range. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an image reading apparatus according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the operation of the image reading apparatus according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example of the configuration of an image reading apparatus according to the second embodiment. [Figure 4]FIG. 4 is a diagram illustrating the operation of the image reading apparatus according to the second embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of an image reading apparatus according to the third embodiment. [Figure 6] FIG. 6 is a diagram illustrating the operation of the image reading apparatus according to the third embodiment. [Figure 7] FIG. 7 is a diagram showing an example of the configuration of an image reading apparatus according to the fourth embodiment. [Figure 8] FIG. 8 is a diagram illustrating the problems of the conventional technology. [Figure 9] FIG. 9 is a diagram illustrating the problems of the conventional technology. [Figure 10] FIG. 10 is a side view showing an outline of the image reading device according to each embodiment. [Figure 11] FIG. 11 is a diagram showing an example of the hardware configuration of an image forming apparatus having the functions of the image reading apparatus according to each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of an image reading device and an image forming device according to the present invention will be described in detail with reference to the drawings. Furthermore, the present invention is not limited to the following embodiments, and the components in the following embodiments include those that would be easily conceived by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, various omissions, substitutions, modifications, and combinations of the components can be made without departing from the spirit of the following embodiments.

[0010] [Problems with the prior art] 8 and 9 are diagrams for explaining the problems of the conventional technology. The problems of the conventional technology will be explained with reference to FIGS.

[0011] Conventional techniques use multiple light sources, such as R (red), G (green), B (blue), and IR (infrared), and sequentially turn on each light source to emit pulsed light. However, as shown in Figure 8(a), this method suffers from the problem that the center position of the RGB light source reading within one line during a reading operation is misaligned in the sub-scanning direction from the center position of the invisible light source (IR light source). In this case, as shown in Figure 8(a), when an image is read at the edge of the image, image data for the hatched area in the figure is obtained using the RGB light source, but image data for the hatched area cannot be obtained when the invisible light source is irradiated. In other words, although these image data are reading the same area, the resulting image data are completely different, as shown in Figure 8(b). This results in a degradation of the quality of the read image.

[0012] Furthermore, with conventional technology, there is a problem of image loss because image data from the RGB light source cannot be obtained during the reading period of the invisible light source. For example, when attempting to read an image such as that shown in Figure 9(a), image data from the RGB light source cannot be obtained during the reading period of the invisible light source, resulting in an image with missing edges as shown in Figure 9(b). However, Figure 9(b) is an illustration for easy visual understanding, and in reality, the image will not be as shown in Figure 9(b) because it is within one line. In reality, problems caused by such image loss include, for example, in the case of a high-density halftone dot document, image loss occurs during the reading period of the invisible light source, making the halftone dots periodically unreadable, resulting in moire.

[0013] In each embodiment below, we will explain the configuration and operation of an image reading device that can reduce the deviation between the center position of reading with a light source in the visible light range and the center position of reading with a light source in the invisible light range, thereby reducing image loss in the visible light range.

[0014] [First embodiment] (Configuration of image reading device) 1 is a diagram showing an example of the configuration of an image reading apparatus according to the first embodiment, with reference to which the configuration of the image reading apparatus 1 according to this embodiment will be described.

[0015] As shown in FIG. 1, the image reading device 1 includes a light source unit 10, a sensor 20, a signal processing unit 30, and a control unit 40.

[0016] The light source unit 10 is a unit that irradiates light (e.g., LED light) onto the document P. As shown in Fig. 1, the light source unit 10 has a light source 11 (first light source) that irradiates red light, a light source 12 (second light source) that irradiates green light, a light source 13 (third light source) that irradiates blue light, and a light source 14 (fourth light source) that irradiates light in the invisible range (e.g., infrared light or ultraviolet light).

[0017] 1 includes a light source 14 that emits one invisible light, but the light source unit 10 is not limited to this and may include two or more invisible light sources. In the following, red light or red color may be referred to as "R," green light or green color as "G," blue light or blue color as "B," and invisible light or invisible color may be referred to as "IR."

[0018] The sensor 20 is a monochrome sensor for reading the reflected light of the light emitted from the light source unit 10 onto the document P. The sensor 20 outputs an image signal based on the read reflected light.

[0019] The signal processing unit 30 is a unit that performs signal processing on the image signal output from the sensor 20. The signal processing unit 30 has an A / D conversion unit 31 that A / D converts the analog image signal output from the sensor 20 into digital image data and outputs the digital image data.

[0020] The control unit 40 is a unit that controls the light irradiation operation from the light source unit 10 and the reading operation by the sensor 20. The control unit 40 includes, for example, a CPU (Central Processing Unit) that executes programs, a ROM (Read Only Memory) that stores programs and data, and a RAM (Random Access Memory) that serves as a work area. The control unit 40 has a mode selector 41 that switches between various reading modes, which will be described later.

[0021] The reading modes include a reading mode using a light source in the invisible range and a reading mode not using a light source in the invisible range. The reading modes using a light source in the invisible range include a normal reading mode and a special reading mode. The special reading mode is a reading mode that reduces the deviation between the reading center position of the RGB light sources (light sources 11 to 13), i.e., the reading center position of the light source in the visible range, and the reading center position of light source 14, i.e., the reading center position of the light source in the invisible range. Any method may be used to reduce the deviation between the reading center position of the light source in the visible range and the reading center position of the light source in the invisible range. For example, there is a method of acquiring an image by increasing the resolution in the sub-scanning direction compared to the normal reading mode. This method will be described in detail below.

[0022] (Image reader operation) 2 is a diagram illustrating the operation of the image reading device according to the first embodiment. The operation of the image reading device 1 according to this embodiment will be described with reference to FIG.

[0023] FIG. 2 illustrates an example of a method for reducing the deviation between the center of reading of a visible light source and the center of reading of an invisible light source in the special reading mode. FIG. 2(a) illustrates operation in a reading mode that does not use an invisible light source, FIG. 2(b) illustrates operation in a normal reading mode, and FIG. 2(c) illustrates operation in the special reading mode. In the special reading mode, the signal processing unit 30 outputs image data with a higher resolution in the sub-scanning direction based on the image signal from the sensor 20 compared to the normal reading mode. For example, in the normal reading mode, the signal processing unit 30 outputs image data with a resolution of 300 dpi in the sub-scanning direction based on the image signal from the sensor 20, and in the special reading mode, the signal processing unit 30 outputs image data with a resolution of 600 dpi in the sub-scanning direction based on the image signal from the sensor 20. In this case, the light source unit 10, under control of the control unit 40, irradiates light from each light source at the timing shown in FIG. 2 according to the respective reading modes. As a result, the resolution is doubled in the special reading mode shown in Figure 2(c) compared to the normal reading mode shown in Figure 2(b), so the width of one line of image data in the sub-scanning direction is halved, and the amount of deviation between the center position of reading with the light source in the visible light range and the center of reading with the light source in the invisible light range is also halved. Furthermore, because the width in the sub-scanning direction is also halved, image loss in the visible light range is also narrowed.

[0024] In the example shown in Figure 2, the resolution of the normal reading mode is 300 [dpi] and the resolution of the special reading mode is 600 [dpi], but this is not limited to this. For example, the resolution of the normal reading mode can be 200 [dpi] and the resolution of the special reading mode can be 500 [dpi], so that the resolution of the special reading mode is higher than the resolution of the normal reading mode.

[0025] Furthermore, when the signal processing unit 30 outputs image data with a higher resolution in the sub-scanning direction based on the image signal from the sensor 20 compared to the normal reading mode, it may also output image data with a lower resolution in the main scanning direction. In other words, to increase the resolution in the sub-scanning direction, it is necessary to slow down the speed at which the document P is read, but by lowering the resolution in the main scanning direction, the time required to read one line can be shortened, and the same productivity as in the normal reading mode can be achieved.

[0026] As described above, in the image reading device 1 according to this embodiment, the light source unit 10 includes the light source 11 that irradiates the document P with red light, the light source 12 that irradiates the document P with green light, the light source 13 that irradiates the document P with blue light, and the light source 14 that irradiates the document P with light in the invisible region. The sensor 20 reads the reflected light of the light irradiated from the light source unit 10 onto the document P. The signal processing unit 30 performs A / D conversion on the image signal read by the sensor 20 to output image data. The control unit 40 controls the image reading device 1 so that the reading mode can be switched between a normal reading mode and a special reading mode, and controls the operation of the light source unit 10. In the special reading mode, the deviation between the center position of the reading of the light sources 11 to 13 and the center position of the reading of the light source 14 is reduced more than in the normal reading mode. Specifically, in the special reading mode, the signal processing unit 30 outputs image data with a higher resolution in the sub-scanning direction based on the image signal from the sensor 20 compared to the normal reading mode. This reduces the deviation between the center position of reading with a light source in the visible light range and the center position of reading with a light source in the invisible light range, thereby reducing image loss in the visible light range.

[0027] [Second embodiment] The image reading device according to the second embodiment will be described, focusing on the differences from the image reading device 1 according to the first embodiment. In this embodiment, a method for reducing the deviation between the center position of reading with a light source in the visible light range and the center position of reading with a light source in the invisible range will be described, in which image data of a light source in the invisible range and image data of a light source in the invisible range of the immediately preceding line are used to output new image data.

[0028] (Configuration of image reading device) 3 is a diagram showing an example of the configuration of an image reading apparatus according to the second embodiment, with reference to which the configuration of an image reading apparatus 1a according to this embodiment will be described.

[0029] 3, the image reading device 1a includes a light source unit 10, a sensor 20, a signal processing unit 30a, and a control unit 40. The operations of the light source unit 10, the sensor 20, and the control unit 40 are the same as those in the first embodiment.

[0030] The signal processing unit 30a has an A / D conversion unit 31 and an image conversion unit 32. The operation of the A / D conversion unit 31 is the same as in the first embodiment.

[0031] In the special reading mode, the image conversion unit 32 outputs image data that is an average value between two lines of the image signal of the light source 14 in the invisible region.

[0032] (Image reader operation) 4 is a diagram illustrating the operation of the image reading device 1a according to the second embodiment, and the operation of the image reading device 1a according to this embodiment will be described with reference to FIG.

[0033] Figure 4 explains an example of a method for reducing the deviation between the center position of the light source for reading in the visible light range and the center position of the light source for reading in the invisible light range in the special reading mode. Of these, Figure 4(a) shows the reading position of the image before processing by the image conversion unit 32, and Figure 4(b) shows the reading position of the image before processing by the image conversion unit 32.

[0034] First, in the special reading mode, the control unit 40 controls the lighting order of the light sources 11-14 when reading an image so that the invisible light source 14 is first or last. In the example shown in FIG. 4, the lighting order of the light sources 11-14 when reading an image in the special reading mode is red → green → blue → invisible color. Furthermore, as shown in FIG. 4(b), the image conversion unit 32 calculates the average value between the image data of the invisible light source and the image data of the previous invisible light source, and outputs the average value as new image data. Furthermore, the image conversion unit 32 is used only for the image data of the invisible light source in the special reading mode, and the image data of the visible light source is output directly without passing through the image conversion unit 32. As a result, as shown in FIG. 4(b), the image data after processing by the image conversion unit 32 becomes image data in which the center position of the reading of the invisible light source is near the center position of the reading of the visible light source, thereby reducing the amount of positional deviation.

[0035] The order in which the light sources 11 to 14 are turned on may be any order as long as the light sources in the invisible area are turned on first or last. For example, the order may be invisible area color → blue → red → green. The calculation method in the image conversion unit 32 may be an average value, or a weighted average weighted by the preceding and following lines.

[0036] As described above, in the image reading device 1a according to this embodiment, in the special reading mode, the control unit 40 controls the lighting order of the light sources 11 to 14 so that the light source 14 is turned on first or last, and the signal processing unit 30 calculates the average value of the image data of the light source 14 and the image data of the previous light source 14, and outputs new image data. As a result, the image data processed by the image conversion unit 32 has a center position of the reading of the light source in the invisible region near the center position of the reading of the light source in the visible light region, and the amount of positional deviation can be reduced.

[0037] [Third embodiment] The image reading device according to the third embodiment will be described, focusing on the differences from the image reading device 1 according to the first embodiment. In this embodiment, the operation including a color mode and a monochrome mode as reading modes will be described.

[0038] (Configuration of image reading device) 5 is a diagram showing an example of the configuration of an image reading apparatus according to the third embodiment. The configuration of an image reading apparatus 1b according to this embodiment will be described with reference to FIG.

[0039] 5, the image reading device 1b includes a light source unit 10, a sensor 20, a signal processing unit 30, and a control unit 40b. The operations of the light source unit 10, the sensor 20, and the signal processing unit 30 are the same as those in the first embodiment. The signal processing unit 30 may also include an image conversion unit 32, as in the second embodiment.

[0040] The control unit 40b has a mode selector 41 that switches between various reading modes. In this embodiment, the reading modes include a color mode and a monochrome mode. As shown in FIG. 5, the color mode and the monochrome mode include a reading mode that uses a light source in the invisible range and a reading mode that does not use a light source in the invisible range, respectively. In addition, the reading mode that uses a light source in the invisible range in the color mode includes a normal reading mode and a special reading mode. In the special reading mode in the color mode, for example, the same operation as the special reading mode in the first or second embodiment described above is performed. This can reduce the deviation between the center position of reading with a light source in the visible range and the center position of reading with a light source in the invisible range.

[0041] The operation in the reading mode using a light source in the invisible region of the monochrome mode will be described later with reference to FIG.

[0042] (Image reader operation) 6 is a diagram illustrating the operation of the image reading device according to the third embodiment. The operation of the image reading device 1b according to this embodiment in a reading mode using a light source in the invisible region of the monochrome mode will be described with reference to FIG.

[0043] FIG. 6(a) shows operation in a reading mode using a color mode invisible light source, in which the control unit 40 sequentially turns on the visible light sources 11-13 separately, and the signal processing unit 30 outputs image data for each of the RGB light sources. On the other hand, in a monochrome mode reading mode using an invisible light source, the control unit 40 simultaneously turns on any of the visible light sources 11-13, and turns on the invisible light source 14 before or after that. The signal processing unit 30 outputs image data for any of the simultaneously turned on light sources as one color, and also outputs image data for the invisible light source. In the example shown in FIG. 6(b), the lighting times of the R light source 11 and the B light source 13 are compressed, so that the G light source 12 is essentially turned on. The light sources that are simultaneously turned on may be the RGB light sources 11-13, any two of these light sources, or any one color light source. The lighting widths of the RGB light sources may be equal, or the lighting widths of each color may be different.

[0044] As a result, when acquiring image data for a light source in the visible light range, if image data for each of RGB is acquired (the example shown in Figure 6(a)), it is necessary to acquire image data for three colors, but in a reading mode using a monochrome invisible light source (the example shown in Figure 6(b)), it is sufficient to acquire image data for only one color as image data for a light source in the visible light range. This shortens the time required to acquire image data, reduces the deviation between the center position of reading for a light source in the visible light range and the center position of reading for a light source in the invisible range, and reduces image loss in the visible light range.

[0045] [Fourth embodiment] The image reading device according to the fourth embodiment will be described, focusing on the differences from the image reading device 1 according to the third embodiment. In this embodiment, the operation will be described in terms of a reading mode that uses a light source in the invisible region of the monochrome mode, including a normal reading mode and a special reading mode.

[0046] (Configuration of image reading device) 7 is a diagram showing an example of the configuration of an image reading apparatus according to the fourth embodiment. The configuration of an image reading apparatus 1c according to this embodiment will be described with reference to FIG.

[0047] 7, the image reading device 1c includes a light source unit 10, a sensor 20, a signal processing unit 30, and a control unit 40c. The operations of the light source unit 10, the sensor 20, and the signal processing unit 30 are the same as those in the first embodiment. The signal processing unit 30 may also include an image conversion unit 32, as in the second embodiment.

[0048] The control unit 40c has a mode selector 41 that switches between various reading modes. In this embodiment, the reading modes include a color mode and a monochrome mode. As shown in FIG. 7, the color mode and the monochrome mode include a reading mode that uses a light source in the invisible range and a reading mode that does not use a light source in the invisible range, respectively. In addition, the reading modes that use a light source in the invisible range in the color mode and the monochrome mode include a normal reading mode and a special reading mode, respectively.

[0049] In this embodiment, the special reading mode in the monochrome mode performs the same operation as the reading mode using the light source in the invisible region in the monochrome mode in the third embodiment described above.

[0050] On the other hand, the normal reading mode in the monochrome mode may be configured to operate in the same manner as either the normal reading mode or the special reading mode in the reading mode using a light source in the invisible range in the color mode, for example.

[0051] As a result, in a reading mode using a light source in the invisible region in monochrome mode, by switching to a special reading mode using the mode selector 41, an operation can be performed to reduce the deviation between the center position of reading with the light source in the visible light region and the center of reading with the light source in the invisible region.

[0052] In each of the above-described embodiments, the reading mode has been described as including a reading mode that does not use a light source in the invisible range, but it may not include a reading mode that does not use a light source in the invisible range.

[0053] [Overview of the Image Reading Device of Each Embodiment] Fig. 10 is a side view showing an outline of an image reading device according to each embodiment. Although Fig. 10 shows the outline configuration of the image reading device 1, the same applies to the image reading devices 1a to 1c described above.

[0054] The image reading device 10 is, for example, a sheet-through type, and includes a reading unit main body 100 (flatbed scanner) and an automatic document feeder (ADF) 102.

[0055] The reading unit main body 100 includes a contact glass 104, a reference white plate 106, a first carriage 108, a second carriage 110, a lens 118, a light receiving element array 122 provided on a light receiving element substrate 120, and a scanner motor 124. The first carriage 108 includes a light source 109 and a mirror 112. The second carriage 110 includes mirrors 114 and 116. The reading unit main body 100 also includes a reading window 134 for reading a document transported by the automatic document feeder 102.

[0056] The automatic document feeder 102 is disposed above the reading unit main body 100 and automatically feeds and transports documents. The automatic document feeder 102 includes a document tray 130, a transport drum 132, a paper discharge roller 136, and a paper discharge tray 138. The automatic document feeder 102 transports documents placed on the document tray 130 toward the transport drum 132, which then transports the documents toward the reading window 134. When the documents pass through the reading window 134, they are exposed to light from the light source 109. Light reflected from the documents is reflected by a mirror 112 of the first carriage 108 and mirrors 114 and 116 of the second carriage 110, passes through a lens 118, and is reduced and imaged on the light receiving surface of the light receiving element array 122 on the light receiving element substrate 120.

[0057] In flatbed scanning, in which an original is fixed on contact glass 104 and scanned by first carriage 108 and second carriage 110, a light source 109 illuminates the original on contact glass 104 from below contact glass 104. Light reflected from the original is reflected by mirror 112 of first carriage 108 and mirrors 114 and 116 of second carriage 110, passes through lens 118, and forms a reduced image on the light receiving surface of light receiving element array 122 on light receiving element substrate 120. At this time, in image reading device 10, first carriage 108 moves in the sub-scanning direction of the original at speed V, and second carriage 110 moves in conjunction with first carriage 108 at half the speed of first carriage 108, 1 / 2V, to read the entire original.

[0058] [Hardware configuration of image forming device] FIG. 11 is a diagram showing an example of the hardware configuration of an image forming apparatus having the functions of the image reading apparatus according to each embodiment.

[0059] As shown in FIG. 11, the image forming device 5 is, for example, a copier or an MFP (Multifunction Peripheral), and includes a scan processing unit 531 that performs the functions of any of the image reading devices 1, 1a to 1c described above, and a print processing unit 532 that forms images.

[0060] The image forming apparatus 5 includes a controller 510, a short-range communication circuit 520, an engine control unit 530, an operation panel 57, and a network I / F 550.

[0061] Of these, the controller 510 has a CPU 501 which is the main part of the computer, a system memory (MEM-P) 502, a north bridge (NB) 503, a south bridge (SB) 504, an ASIC (Application Specific Integrated Circuit) 506, a local memory (MEM-C) 507 which is a storage unit, an HDD controller 508, and an HD 509 which is a storage unit. Note that an SSD (Solid State Drive) may be used as the storage unit.

[0062] The NB 503 and the ASIC 506 are connected via an AGP (Accelerated Graphics Port) bus 521 .

[0063] Of these, the CPU 501 is a control unit that performs overall control of the image forming apparatus 5 including the image reading device 1. The NB 503 is a bridge that connects the CPU 501 with the MEM-P 502, the SB 504, and the AGP bus 521, and includes a memory controller that controls reading and writing to the MEM-P 502, a PCI (Peripheral Component Interconnect) master, and an AGP target.

[0064] The MEM-P 502 includes a ROM (Read Only Memory) 502a, which is memory for storing programs and data that realize the functions of the controller 510, and a RAM (Random Access Memory) 502b, which is used for expanding the programs and data and as a drawing memory during memory printing. The programs stored in the RAM 502b may be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM, CD-R, or DVD.

[0065] The SB 504 is a bridge for connecting the NB 503 with PCI devices and peripheral devices. The ASIC 506 is an integrated circuit (IC) for image processing purposes that has hardware elements for image processing, and serves as a bridge connecting the AGP bus 521, PCI bus 522, HDD controller 508, and MEM-C 507.

[0066] The ASIC 506 includes a PCI target and AGP master, an arbiter (ARB) that forms the core of the ASIC 506, a memory controller that controls the MEM-C 507, a plurality of DMACs (Direct Memory Access Controllers) that perform image data rotation and the like using hardware logic, and a PCI unit that transfers data between the scan processing unit 531 and the print processing unit 532 via a PCI bus 522. Note that the ASIC 506 may be connected to an interface such as a USB (Universal Serial Bus) interface or IEEE1394 (Institute of Electrical and Electronics Engineers 1394).

[0067] MEM-C507 is a local memory used as an image buffer for copying and a code buffer. HD509 is a storage for storing image data, font data used during printing, forms, etc. HD509 controls the reading and writing of data from and to HD509 under the control of CPU501.

[0068] The AGP bus 521 is a bus interface for a graphics accelerator card proposed to speed up graphics processing. The AGP bus 521 can speed up the graphics accelerator card by directly accessing the MEM-P 502 at high throughput.

[0069] Further, the short-range communication circuit 520 includes a short-range communication antenna 520a. The short-range communication circuit 520 is a communication circuit such as NFC or Bluetooth (registered trademark).

[0070] The engine control unit 530 is further configured with a scan processing unit 531 and a print processing unit 532. The operation panel 57 includes a panel display unit 57a, such as a touch panel, that displays current setting values, selection screens, etc. and accepts input from the operator, and operation keys 57b, such as a numeric keypad that accepts setting values ​​for image formation conditions such as density settings and a start key that accepts a copy start command. The panel display unit 57a accepts touch input from the user, and the user can use a finger or a pen to enter numbers into input boxes displayed on the screen, select from pull-down menus, turn check boxes on / off, etc. The operation keys 57b may include input means such as a trackball or touchpad in addition to the numeric keypad, etc.

[0071] The controller 510 controls the entire image forming apparatus 5, for example, controlling drawing, communication, input from the operation panel 57, etc. The scan processing unit 531 performs image reading using one of the image reading devices 1, 1a to 1c described above to generate image data. The print processing unit 532 includes a transfer unit that transfers an image using color materials such as a toner image onto a conveying medium such as paper, a fixing unit that fixes the image, a heating unit or a drying unit, etc., and forms an image on paper. The scan processing unit 531 or the print processing unit 532 also performs image processing such as error diffusion and gamma conversion.

[0072] The paper is an example of a transport medium. The transport medium may be a material other than paper, such as a film or a plastic sheet, as long as it can be placed in a paper feed tray provided in the image forming device 5 and transported and output in response to a paper output instruction.

[0073] The network I / F 550 is an interface for performing data communication using a communication network. The short-range communication circuit 520 and the network I / F 550 are electrically connected to the ASIC 506 via a PCI bus 522.

[0074] Although FIG. 11 shows an example in which the image forming apparatus 5 has an electrophotographic image forming mechanism, the image forming apparatus 5 may have another image forming mechanism such as an inkjet type.

[0075] Each function of each embodiment described above can be realized by one or more processing circuits. Here, the term "processing circuit" includes a processor programmed to perform each function by software, such as a processor implemented by an electronic circuit, as well as devices such as an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field-Programmable Gate Array), and conventional circuit modules designed to perform each of the functions described above.

[0076] The programs executed by the control unit 40 (40b, 40c) of the image reading device 1 (1a to 1c) of each of the above-described embodiments may be provided by being pre-installed in a ROM or the like. The programs executed by the control unit 40 (40b, 40c) of the image reading device 1 (1a to 1c) of each of the above-described embodiments may be provided as a computer program product by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), a flexible disk (FD), a CD-R (Compact Disk-Recordable), or a DVD (Digital Versatile Disk). The programs executed by the control unit 40 (40b, 40c) of the image reading device 1 (1a to 1c) of each of the above-described embodiments may be stored on a computer connected to a network such as the Internet and downloaded via the network. The programs executed by the control unit 40 (40b, 40c) of the image reading device 1 (1a to 1c) of each of the above-described embodiments may be provided or distributed via a network such as the Internet.

[0077] Furthermore, the program executed by the control unit 40 (40b, 40c) of the image reading device 1 (1a to 1c) in each of the above-mentioned embodiments has a modular structure including each of the above-mentioned functional units, and in actual hardware, the CPU (processor) reads the program from the storage device and executes it, thereby loading each of the above-mentioned functional units onto the main storage device, and each functional unit is generated on the main storage device.

[0078] The aspects of the present invention are as follows. <1> An image reading device that reads a document, a light source unit having a first light source that irradiates the document with red light, a second light source that irradiates with green light, a third light source that irradiates with blue light, and a fourth light source that irradiates with light in the invisible range; a sensor that reads reflected light of light irradiated onto the document from the light source unit; a signal processing unit that performs A / D conversion on the image signal read by the sensor and outputs image data; a control unit that controls the image reading device so that the reading mode can be switched between a normal reading mode and a special reading mode, and that controls the operation of the light source unit; Equipped with In the special reading mode, the image reading device reduces the deviation between the central reading positions of the first light source, the second light source, and the third light source and the central reading position of the fourth light source more than in the normal reading mode. <2> In the special reading mode, the signal processing unit outputs the image data with a higher resolution in the sub-scanning direction based on the image signal from the sensor compared to the normal reading mode. <1> The image reading apparatus is described in <3> In the special reading mode, the signal processing unit outputs the image data with a lower resolution in the main scanning direction based on the image signal from the sensor, compared to the normal reading mode. <2> The image reading apparatus is described in <4> In the special reading mode, the control unit controls a lighting order of the first light source, the second light source, the third light source, and the fourth light source so that the lighting order of the fourth light source is first or last, the signal processing unit calculates an average value of the image data of the fourth light source and the immediately preceding image data of the fourth light source, and outputs new image data. <1> The image reading apparatus is described in <5> the control unit is capable of switching the reading mode between a color mode and a monochrome mode, the color modes include the normal reading mode and the special reading mode; In the monochrome mode, the control unit simultaneously turns on any one of the first light source, the second light source, and the third light source, and turns on the fourth light source before or after the any one of the first light source, the second light source, and the third light source; the signal processing unit outputs image data of one color as image data corresponding to the arbitrary light source. <1> ~ <4> 1 is an image reading apparatus according to any one of claims 1 to 9. <6> the monochrome mode includes a normal reading mode and a special reading mode; In the special reading mode of the monochrome mode, the control unit simultaneously turns on any one of the first light source, the second light source, and the third light source, and turns on the fourth light source before or after the any one of the first light source, the second light source, and the third light source; the signal processing unit outputs image data of one color as image data corresponding to the arbitrary light source. <5> The image reading apparatus is described in <7> In the normal reading mode of the monochrome mode, the same operation as in the normal reading mode or the special reading mode of the color mode is performed. <6> The image reading apparatus is described in <8> The aforementioned <1> ~ <7> 10. An image forming apparatus including the image reading device according to claim 9. [Explanation of symbols]

[0079] 1, 1a to 1c Image reading device 5. Image forming device 10 Light source section 11~14 Light source 20 sensors 30, 30a Signal processing section 31 A / D conversion section 32 Image conversion section 40, 40b, 40c control section 41 Mode Selector 57 Operation Panel 57a Panel display 57b Operation keys 100 Reading unit body 102 Automatic document feeder 104 Contact Glass 106 Standard white board 108 1st Carriage 109 Light source 110 2nd Carriage 112, 114, 116 Mirror 118 Lens 120 Photodetector substrate 122 Photodetector array 124 Scanner Motor 130 Document tray 132 Transport drum 134 Reading window 136 Paper ejection roller 138 Paper output tray 501 CPU 502 system memory 502a ROM 502b RAM 503 Northbridge 504 Southbridge 506 ASIC 507 Local Memory 508 HDD controller 509 HD 520 Near field communication circuit 520a short-range communication antenna 521 AGP Bus 522 PCI bus 530 Engine control unit 531 Scan processing section 532 Print processing unit 550 Network I / F P Manuscript [Prior art documents] [Patent documents]

[0080] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-266449

Claims

1. An image reading device that reads a document, a light source unit including a first light source that irradiates the document with red light, a second light source that irradiates the document with green light, a third light source that irradiates the document with blue light, and a fourth light source that irradiates the document with light in an invisible region; a sensor that reads reflected light of light irradiated onto the document from the light source unit; a signal processing unit that performs A / D conversion on the image signal read by the sensor and outputs image data; a control unit that controls the image reading device so that the reading mode can be switched between a normal reading mode and a special reading mode, and that controls the operation of the light source unit; Equipped with In the special reading mode, the image reading device reduces the deviation between the central positions of the readings of the first light source, the second light source, and the third light source and the central position of the readings of the fourth light source more than in the normal reading mode.

2. 2. The image reading device according to claim 1, wherein in the special reading mode, the signal processing unit outputs the image data with a higher resolution in the sub-scanning direction based on the image signal from the sensor than in the normal reading mode.

3. 3. The image reading device according to claim 2, wherein in the special reading mode, the signal processing unit outputs the image data with a lower resolution in the main scanning direction based on the image signal from the sensor compared to the normal reading mode.

4. In the special reading mode, the control unit controls a lighting order of the first light source, the second light source, the third light source, and the fourth light source so that the lighting order of the fourth light source is first or last, 2. The image reading device according to claim 1, wherein the signal processing unit calculates an average value of the image data of the fourth light source and the immediately preceding image data of the fourth light source, and outputs new image data.

5. the control unit is capable of switching the reading mode between a color mode and a monochrome mode, the color modes include the normal reading mode and the special reading mode; In the monochrome mode, the control unit simultaneously turns on any one of the first light source, the second light source, and the third light source, and turns on the fourth light source before or after the any one of the first light source, the second light source, and the third light source; 5. The image reading device according to claim 1, wherein the signal processing unit outputs image data of one color as the image data corresponding to the arbitrary light source.

6. the monochrome mode includes a normal reading mode and a special reading mode; In the special reading mode of the monochrome mode, the control unit simultaneously turns on any one of the first light source, the second light source, and the third light source, and turns on the fourth light source before or after the any one of the first light source, the second light source, and the third light source; 6. The image reading device according to claim 5, wherein the signal processing unit outputs image data of one color as the image data corresponding to the arbitrary light source.

7. 7. The image reading device according to claim 6, wherein in the normal reading mode of the monochrome mode, the same operation as in the normal reading mode or the special reading mode of the color mode is performed.

8. An image forming apparatus comprising the image reading device according to claim 1.

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