Image reading device

Abstract

To improve the efficiency when an image is read in two colors, in an image reading device including light sources of three or more colors.SOLUTION: An image reading device 1 including light sources (a light source unit 10) of three or more colors includes: a conveying unit 30 which conveys documents; a reading unit 20 which reads the documents; and a control unit 70 which switches between a full-color mode and a two-color image mode. In the full-color mode, a full-color image is read by the reading unit while all of the light sources are sequentially switched and turned on, and in the two-color image mode, a two-color read image is read by the reading unit while the light sources are turned on a smaller number of times than those of the full-color mode and two target colors are extracted and cut out from the two-color read image to obtain an output image. In the two-color mode, at least one time of the times is set such that the light sources of two colors are turned on.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an image reading apparatus.

Background Art

[0002] In a reading apparatus that sequentially switches a plurality of reading colors (for example, R (red), G (green), B (blue)) to read a document image, there is a technique in which, even during two-color copying (two-color reading), the reading colors are sequentially switched to R, G, and B and reading is performed in the same manner as during full-color reading. In conventional full-color reading, since lighting is performed by sequentially switching the reading colors and image processing is performed on the premise of full color, there has been a problem that the reading speed is one-third that of monochrome and copy printing takes time. For example, Patent Document 1 discloses a technique for reading an image at high speed and with low power by causing two light sources to emit light instead of all three light sources. However, there is room for improvement in the combination and control of the light sources to be lit with respect to the combination of colors to be read during two-color reading.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to improve the efficiency when reading an image in two colors in an image reading apparatus including three or more light sources.

Means for Solving the Problems

[0004] In order to solve the above-described problems, the present invention is an image reading apparatus including three or more light sources, a conveyance unit that conveys a document, a reading unit that reads the document, and a control unit that switches between a full-color mode and a two-color image mode, wherein the full-color mode is a mode in which all of the light sources are sequentially switched on and a full-color image is read by the reading unit, The two-color image mode is a mode in which the light source is turned on fewer times than in the full-color mode, the reading unit reads the two-color image, and the two desired colors are extracted and cut out from the two-color image to form the output image, and the setting is such that the two-color light source is turned on at least once out of the number of turns. death, The light source is positioned in a direction intersecting the direction in which the document is read, and the color of the light is switched for each line in which the document is read. When the two-color image mode is a two-color output image of green and black, the control unit combines two readings: one using the green light source and another using the simultaneous illumination of the red and blue light sources. It shall be considered as such. [Effects of the Invention]

[0005] According to the present invention, the efficiency of reading an image in two colors can be improved in an image reading device equipped with three or more light sources. [Brief explanation of the drawing]

[0006] [Figure 1] This figure illustrates an example of the configuration of an image reading device according to an embodiment of the present invention. [Figure 2] This is a block diagram illustrating an example of the control functions provided by the image reading device. [Figure 3] This diagram illustrates an example of two-color reading and lighting, where a red (R) light source and a green (G) light source are illuminated. [Figure 4] This diagram illustrates the timing of LED illumination in a color (three-color) system. [Figure 5] This diagram illustrates the timing of LED illumination in two-color printing. [Figure 6] This diagram illustrates an example of lighting up a G-color light source and an R-color light source as a two-color reading and lighting system. [Figure 7] This figure shows an image obtained by scanning a color patch document with the red light source turned on. [Figure 8] This figure shows an image obtained by scanning a color patch document with a G-color light source turned on. [Figure 9] This figure shows an image obtained by scanning a color patch document with a B-color light source turned on. [Figure 10] This figure shows an image obtained by scanning a color patch document with a G-color light source turned on. [Figure 11] This figure shows an image obtained by scanning a color patch document with a G-color light source turned on. [Figure 12] This figure shows an image obtained by scanning a color patch document with the red light source (RB) turned on. [Figure 13] This diagram illustrates an example of lighting up two colors, specifically an RG color light source and an RB color light source. [Figure 14] This flowchart illustrates an example of how to adjust the lighting duty cycle. [Figure 15] This diagram illustrates an example of duty cycle control (RB and G lights up twice). [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described below with reference to the attached drawings. In each drawing illustrating the embodiments of the present invention, components such as members and parts having the same function or shape will be given the same reference numerals to the extent possible so that they can be identified, and their description will be omitted after they have been described once.

[0008] The image reading device according to the present invention has a two-color image mode (also referred to as "two-color reading mode") which reads images in two colors, and which is more efficient than the full-color mode due to dedicated image processing. One embodiment of an image forming apparatus is, for example, an image reading apparatus equipped with three or more light sources (light source unit 10), comprising a transport unit (transport unit 30) for transporting a document, a reading unit (reading unit 20) for reading the document with an image sensor, and a control unit (control unit 70) for switching between a full-color mode and a two-color image mode. The full-color mode is a mode in which all light sources are sequentially switched on and lit, and the reading unit reads a full-color image. The two-color image mode is a mode in which the light sources are lit fewer times than in the full-color mode, the reading unit reads a two-color image, and the two target (selected) colors are extracted and cut out from the two-color image to form an output image. The apparatus has a setting to light up the two light sources in at least one of the above-mentioned number of times. (The part in parentheses corresponds to the configuration in Figure 1 described later as an example.)

[0009] By doing so, in an image reading apparatus including three or more light sources, it is possible to improve the productivity during two-color reading for reading an image with two colors. Further, it is possible to improve the combination and control of light sources during reading with respect to the combination of colors during two-color reading (the combination of colors for two-color printing). Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0010] First, a configuration example of an image reading apparatus according to an embodiment of the present invention will be described. FIG. 1 is a diagram for explaining a configuration example of the image reading apparatus, and shows an example of an image reading apparatus of a sequential lighting reading method. The image reading apparatus 1 includes a light source unit 10, a reading unit 20, a conveyance unit 30, a contact glass 40, a white reference plate 50, an external light prevention shutter 60, and a control unit 70. The light source unit 10 is provided with an LED array 13 serving as three or more light sources on a substrate 11. In FIG. 1, a configuration example having light sources of R (red), G (green), and B ( blue ) is shown. The reading unit 20 has an image sensor light receiving unit (also referred to as an “image sensor”) 21, switches and lights two or more light sources, and reads a document placed on the contact glass 40 with the image sensor 21. The conveyance unit 30 conveys the document. In FIG. 1, the conveyance unit 30 shows an example configured by a pair of two rollers. The white reference plate 50 is used as a reference when adjusting the light amount. A gap of length A is provided between the contact glass 40 and the white reference plate 50.

[0011] The control unit 70 controls the entire image reading apparatus 1 and executes an image reading process. The control unit 70 switches between the full-color mode and the two-color image mode described above as the image reading process. In full-color mode, the control unit 70 controls the light source unit 10 to sequentially switch and light up all the light sources of all colors so that the image sensor 21 can read a full-color image. In two-color image mode, the control unit 70 controls the light source to light up fewer times than in full-color mode so that the image sensor 21 can read a two-color image. In this case, the two-color image mode (image reading device 1) has a setting (combination of output color and lighting color) in which at least one of the aforementioned number of times the light source of two colors is lit. Furthermore, in two-color image mode, the control unit 70 extracts and cuts out the desired (target) two colors from the two-color read image to produce an output image (two-color image).

[0012] Here, the control function of the image reading device according to this embodiment will be described. Figure 2 is a block diagram illustrating an example of the control functions provided by the image reading device. The control unit 70 of the image reading device 1 comprises a processor, a CPU (Central Processing Unit) 71, and a memory 73. The control unit 70 is connected to the light source unit 10, the reading unit 20, and the operation unit 80 by a bus 90.

[0013] Memory 73 consists of volatile and non-volatile storage devices such as ROM (Read Only Memory), RAM (Random Access Memory), EEPROM (Electrically Erasable and Programmable ROM), and hard disks. Memory 73 stores the basic program of the image reading device 1, programs such as image reading programs for controlling the image reading process, and system data and other data necessary to execute these programs, and is also used as work memory for the CPU 71.

[0014] The CPU 71, for example, reads various programs stored in ROM and loads them into RAM, and controls various processes such as basic processing and image reading processing according to the loaded programs.

[0015] The image reading device 1 is preferably constructed as an image reading device that streamlines image reading processing by reading programs recorded on computer-readable recording media such as ROM, EEPROM, EPROM, flash memory, flexible disk, CD-ROM (Compact Disc Read Only Memory), CD-RW (Compact Disc Rewritable), DVD (Digital Video Disk), SD (Secure Digital) card, MO (Magneto-Optical Disc), etc., and loading them into memory 73.

[0016] The operation unit 80 is equipped with various operation keys such as a start key and function keys, as well as a display unit (for example, a liquid crystal display). Various commands necessary to cause the image reading device 1 to perform the desired operation are input to the operation unit 80 using the operation keys, and the display unit shows the contents of the various commands input by the operation keys and various information notified to the user from the image reading device 1. As an example, the control unit 70 displays a screen on the operation unit 80 prompting the user to select the output color for the two-color image mode, and receives information entered by the user via various operation keys to switch between full-color mode and two-color image mode.

[0017] The control unit 70 (CPU 71) controls the lighting of the LED array 13 (for example, red light source, green light source, blue light source) of the light source unit 10. The control unit 70 lights up the light sources of each color according to the mode and causes the image sensor 21 of the reading unit 20 to read the image. In the reading unit 20, the image sensor 21 converts the reading light of the original image formed by the 1:1 imaging lens into photoelectric light and outputs the read image data.

[0018] The image reading device 1, based on the control of the control unit 70, lights up the light source from the LED array 13 of the light source unit 10 and reads the document with the image sensor 21. At this time, in monochrome reading, the lights are lit in the order G→G→G, and in color reading, the lights are lit in the order B→G→R to form a line image. In the following embodiments, the combination of light sources to be illuminated and the control of these in relation to the color combinations during two-color reading performed by the image reading device 1 described above will be explained.

[0019] Embodiment 1. In this embodiment, the case in which the light source unit 10 is lit twice in the two-color image mode will be described. In two-color image mode, the image reading device 1 changes from three sequential illuminations of the RGB light source to two sequential illuminations to read the document. This reduces the number of LED illuminations during reading, thereby improving reading productivity. Referring to Figures 3 to 5, we will explain image reading in full-color mode and two-color image mode. Here, we will explain using the case where three colors, RGB, are used as the full-color mode, and two colors, RB, are used as the two-color image mode. Figure 3 shows an example of two-color reading and lighting, where the R and B colors are lit. The image reading device 1 lights the LED of the optimal color according to the two colors to be output.

[0020] Figure 4 illustrates the LED lighting timing for color (three colors). In sequential three-color lighting, each RGB element is lit to read one line. On the other hand, Figure 5 illustrates the LED lighting timing for two-color printing. Figure 5 shows the timing for an example of lighting in Figure 3, where one line is lit with only two colors (R and B), eliminating the need to light one color. This improves the productivity of two-color printing.

[0021] Here, we will explain an example of the process of selecting two output colors. In this embodiment, the two colors to be output are determined by user input. The control unit 70 prompts the user to select two output colors, for example via the operation unit 80, and receives the output color selected by the user. The control unit 70 sets the output color received from the operation unit 80 and determines the number of LED colors and the types of colors to light up according to this setting. At this time, the reading unit 20 also acquires shading data according to the lighting settings of the document.

[0022] Table 1 shows an example of a combination of output color selection and illumination color (illumination pattern). [Table 1]

[0023] Figure 6 shows an example of lighting up a combination of a G-color light source and two light sources (RB-color light sources) with R-color and B-color as shown in Table 1.

[0024] Next, we will explain the process of extracting the two-color scanned image obtained by the reading unit 20 from the original document. The image reading device 1 can perform more efficient control than when using full color by limiting the output to two colors. The process of extracting a desired two-color image from a two-color scanned image using the results of reading a color patch original when an arbitrary color light source is illuminated will be explained.

[0025] (1) In the case of two-color printing (black and red) (with red light source and green light source illuminated) This section explains an example of the process for printing in two colors, black and red, using two different light sources. When scanning an original image and printing it as two-color data (red / black), there are two methods for obtaining the scanned data: one using an image scanned with a red light source and another using image data scanned with a green light source. Figure 7 shows the image obtained when scanning a color patch document with the R color light source illuminated, and Figure 8 shows the image obtained when scanning a color patch document with the G color light source illuminated. Table 2 shows the luminance information (luminance of the extracted patch (R / G)) of the extracted colors in Figures 7 and 8, arranged from left to right.

[0026] [Table 2]

[0027] As shown in FIGS. 7 and 8, the control unit 70 extracts the R color patch as the extraction target color from each of the images of the R color light source lighting and the G color light source lighting. In FIGS. 7 and 8, the patches of the extraction target color are shown surrounded by a dashed line. The control unit 70 acquires luminance information (Table 2) from the R color patches of the extracted R color light source and G color light source.

[0028] In the control unit 70, by comparing the brightness of the R color light source and the G color light source at the same coordinates and performing the brightness comparison as follows, it can be simply separated into two-color data. · The image data containing the R color component is the location where the brightness of the R color light source data is greater than the brightness of the G color light source data (brightness of R color light source data > brightness of G color light source data). · The black data not containing the R color component is the location where the brightness of the R color light source data is less than the brightness of the G color light source data (brightness of R color light source data < brightness of G color light source data).

[0029] Since the data with the same brightness only needs to be separated into either image data or black data, it is advisable to preset the data with the same brightness to be either image data or black data, and the control unit 70 separates it based on the setting.

[0030] (2) In the case of two-color printing of black and blue (lighting of B color light source and G color light source) Next, a processing example in the case of performing two-color printing of black and blue with two types of light source lighting will be described. The original manuscript is read using two types of B color light source and G color light source, and by comparing the brightness of the read image, it is possible to extract the two colors of blue / black. FIG. 9 is an image when reading a color patch original manuscript with the B color light source lit, and FIG. 10 is an image when reading a color patch original manuscript with the G color light source lit. Also, Table 3 is the values arranged in order from the left of the luminance information (patch luminance (B / G) of the extraction target) of the extracted colors in FIGS. 9 and 10.

[0031]

Table 3

[0032] The control unit 70 extracts a B-color patch as the extraction target color from each of the images with the B-color light source lit and the image with the G-color light source lit. In FIGS. 9 and 10, the patches of the extraction target color are shown surrounded by a dashed line. In the control unit 70, by comparing the brightnesses at the same coordinates of the B-color light source and the G-color light source and performing the brightness comparison as follows, it can be simply separated into two-color data. · The portion where the brightness of the B-color light source data is greater than the brightness of the G-color light source data (brightness of B-color light source data > brightness of G-color light source data) is image data containing a B-color component · The portion where the brightness of the B-color light source data is less than the brightness of the G-color light source data (brightness of B-color light source data < brightness of G-color light source data) is black data that does not contain a B-color component Note that data with the same brightness may be preset so that data with the same brightness is regarded as image data or black data.

[0033] (3) In the case of two-color printing of green and black (lighting of G-color light source and R + B-color light source) Subsequently, an example of performing two-color printing of green and black with lighting of two types of light sources will be described. The G-color light source may be used in monochrome reading, and it is difficult to distinguish colors from black. Therefore, by combining two readings, namely the reading with the G-color light source and the reading with simultaneous lighting of the R-color light source and the B-color light source (RB-color light source), the discrimination accuracy can be improved. FIG. 11 is an image when reading a color patch manuscript with the G-color light source lit, and FIG. 12 is an image when reading a color patch manuscript with the RB-color light source lit. Also, Table 4 shows the luminance information of the extracted colors (patch luminance of the extraction target (G-color and RB two colors)) in FIGS. 11 and 12 arranged in order from the left.

[0034]

Table 4

[0035] The control unit 70 extracts a G-color patch as the extraction target color from each of the images of the G-color light source lighting and the RB-color light source lighting. In FIGS. 11 and 12, the patches of the extraction target color are shown surrounded by a dashed line. In the control unit 70, by comparing the brightness at the same coordinates of the G-color light source and the RB-color light source and performing the brightness comparison as follows, it can be simply separated into two-color data. · The location where the brightness of the G-color light source data is greater than the brightness of the RB-color light source data (brightness of G-color light source data > brightness of RB-color light source data) is the image data containing the G-color component · The location where the brightness of the G-color light source data is less than the brightness of the RB-color light source data (brightness of G-color light source data < brightness of RB-color light source data) is the black data not containing the G-color component Note that data with the same brightness may be preset so that data with the same brightness is either image data or black data.

[0036] As described above in (1) to (3), the control unit 70 lights the light sources of the lighting colors (Table 1) associated with the output color selected by the user twice, causes the reading unit 20 to read a two-color reading image, and receives the two-color reading images for each lighting. After that, the control unit 70 extracts and cuts out the two target colors from the two-color reading images. Therefore, from the two-color reading images for each lighting color, one of the two colors to be output is extracted, and using the luminance of the color extracted for each lighting color, a two-color image (output image) of the output color selected by the user is obtained.

[0037] As described above, the image reading apparatus of the present embodiment has a full-color mode in which, in an apparatus equipped with three or more light sources, all of the light sources are sequentially switched on and a full-color image is read by the image sensor from a document, a conveying means for conveying the document, a control means (control unit) for changing the image conversion method for the full-color mode and the two-color image mode, and in the two-color image mode, a mode (two-color image mode) more efficient than full-color by dedicated image processing, and has a method for cutting out the two extracted target colors from the two-color reading images. In addition, the image reading apparatus of the present embodiment has a control means for increasing the reading speed by reducing the number of lighting times to two in the two-color image mode.

[0038] According to the embodiment described above, in two-color image mode, the number of illumination cycles can be reduced to two, thereby increasing the reading speed. This improves the productivity of the image reading device when reading two colors.

[0039] Embodiment 2. This embodiment describes other examples of combinations of output color selection and illumination color. In Embodiment 1, the light source color that lights up twice is: • Monochromatic: R→G→R→G···(Figure 4) • Single color + multiple colors: G → RB → G → RB... (Figure 6) Table 1 shows an example of such colors, but both times multiple colors may be used. For example, the following lighting colors can be used. • Multiple colors + multiple colors: RG → RB → RG → RB... (Figure 13)

[0040] Additionally, for single-color + multiple-color combinations, other multiple-color combinations can also be used. Table 5 shows other examples of output color selection and illumination color combinations. Table 5 adds two more combinations to Table 1. [Table 5]

[0041] For example, in the case of two-color printing using red and black, if the user can select a pattern for illuminating the red (R) color light source and the GB color light source, it is possible to generate output images with different color sensitivity performance, thus providing the user with a variety of options. Furthermore, using multiple light source colors during the two-light cycle can improve the accuracy of distinguishing between the two colors. Furthermore, the control unit 70 of the image reading device 1 should have a function that limits the colors used for two-color reading (the colors to be copied in two colors), and switches to full-color mode when reading any other colors.

[0042] As described above, the image reading device of this embodiment improves color sensitivity by switching between lighting the R light and the G+B light twice when the output image is two-color (red / black). Furthermore, the image reading process in this embodiment limits the colors to be copied in two colors (colors during two-color reading), and controls the system to switch to full-color mode when copying any other colors (color combinations). In this way, complex control in the control unit 70 is avoided, and two-color images can be read efficiently.

[0043] Embodiment 3. This embodiment describes improvements related to the LED lighting duty cycle. Generally, the illumination duty cycle of the LED used as the reading light source is determined by adjusting the light intensity when the power is turned on. At this time, the image reading device 1 reads the white reference plate 50 and adjusts the duty cycle from its peak value.

[0044] In the embodiment of the present invention, the image reading device 1 is compatible with two-color image modes, and therefore, it is preferable to read the document with a lighting duty cycle specialized for distinguishing colors in two colors. This makes image processing in two-color image modes more efficient. Adjustments in full-color mode should only be made when the power is turned on; no further changes will be made after this point. Therefore, in this embodiment, the control unit 70 controls the illumination duty cycle according to the two-color reading setting (selection of two-color image mode), enabling the document to be read with the appropriate amount of light for the purpose.

[0045] Figure 14 is a flowchart illustrating an example of adjusting the lighting duty cycle. When the power is turned on in the image reading device 1 (S11), the control unit 70 prompts the user to select a scan mode (for example, full-color mode, two-color image mode, or monochrome mode) via the operation unit 80 (S12), and adjusts the light intensity of the light source unit 10 for each selected mode (for each three-color lighting and two-color lighting pattern) (S13). The control unit 70 sets the scan mode selected by the user and sets the duty cycle according to the selected mode (S14). After that, the control unit 70 lights up the light source corresponding to the selected mode and reads the document (S15).

[0046] Furthermore, the duty cycle can be freely set by the user according to the color settings. For example, the control unit 70 may display a screen prompting the user to input a duty cycle setting according to the color settings via the operation unit 80, and receive the duty cycle setting specified by the user. Figure 15 illustrates an example of duty cycle control (RB and G lights flashing twice). The control unit 70 controls the lighting intervals to be indicated by arrows according to the color setting.

[0047] As described above, the image reading device of this embodiment has a control means for changing the illumination duty cycle of the light-emitting LED. In this way, it is possible to change the illumination duty cycle according to the two-color reading setting, and the color tone and image quality of the two-color read image can be improved.

[0048] Other embodiments. In the embodiments described above, an example was explained in which the light source is turned on twice to read a two-color image. However, this is not the only example; it is possible to improve efficiency compared to the full-color mode by turning on the light source fewer times than in full-color mode to read a two-color image. Furthermore, the image reading device 1 in each of the above embodiments can be provided in an image forming apparatus. The image forming apparatus may be, for example, a color copier comprising the image reading device 1 and an imaging device, forming a single image using four toners: yellow (Y), cyan (C), magenta (M), and black (BK). The imaging device, for example, forms a toner image on a recording medium based on the image data acquired by the image reading device 1. The imaging device comprises an image forming means, a fixing device for fixing the toner image formed on the recording medium by the image forming means onto the recording medium, and a recording medium transport device for transporting the recording medium toward the image forming means. A detailed explanation is omitted here.

[0049] Examples of the present invention are as follows: <1> An image reading device equipped with three or more light sources, A transport unit that transports the manuscript, A reading unit that reads the aforementioned document, It includes a control unit that switches between full-color mode and two-color image mode, The full-color mode is a mode in which all the light sources are sequentially switched on and lit, and the reading unit reads a full-color image. The two-color image mode is a mode in which the light source is lit fewer times than in the full-color mode, the reading unit reads the two-color image, and the two target colors are extracted and cut out from the two-color image to form an output image, and the image reading device is characterized in that it has a setting to light up the two-color light source at least once out of the number of times. <2> When the two-color image mode is a two-color output image of red and black, the control unit controls the red light source and green and blue The aforementioned light source is characterized by switching between and turning on the light source. <1> This is the image reading device described in [reference]. <3> The control unit is characterized in that, in the two-color image mode, it limits the two selectable colors, and when it reads a color other than the limited two colors, it switches to the full-color mode. <1> or <2> This is the image reading device described in [reference]. <4> The control unit is characterized by changing the illumination duty cycle of the light source that emits light. <1> from <3> The image reading device is one of the devices described in any one of the following. <5> The control unit is characterized in that, in the two-color image mode, the light source is turned on twice. <1> from <4> The image reading device is one of the devices described in any one of the following. <6> The reading unit is characterized by reading the original document using an image sensor. <1> from <5> The image reading device is one of the devices described in any one of the following.

[0050] It should be noted that the present invention is not limited to the embodiments shown above. Within the scope of the present invention, each element of the above embodiments can be changed, added to, or modified in ways that would be easily conceivable to those skilled in the art. Furthermore, two or more embodiments described above can be combined as appropriate. [Explanation of Symbols]

[0051] 1. Image reading device 10 Light source section 11 circuit boards 13 LED array 20 Reading section 21 Image sensor light receiving section (image sensor) 30 Conveying section 40 Contact Glasses 50 White reference plate 60. External light-blocking shutter 70 Control Unit 71 CPU 73 memory 80 Control section 90 bus [Prior art documents] [Patent Documents]

[0052] [Patent Document 1] Japanese Patent Publication No. 2015-012353

Claims

1. An image reading device equipped with three or more light sources, A transport unit that transports the manuscript, A reading unit that reads the aforementioned document, It includes a control unit that switches between full-color mode and two-color image mode, The full-color mode is a mode in which all the light sources are sequentially switched on and lit, and the reading unit reads a full-color image. The two-color image mode is a mode in which the light source is turned on fewer times than in the full-color mode, the reading unit reads the two-color image, and the two desired colors are extracted and cut out from the two-color image to form the output image, and has a setting to turn on the two-color light source at least once out of the number of turns. The light source is positioned in a direction intersecting the direction in which the document is read, and the color of the light is switched for each line in which the document is read. When the two-color image mode is a two-color output image of green and black, the control unit combines two readings: one using the green light source and another using the simultaneous illumination of the red and blue light sources. An image reading device characterized by the following:

2. When the two-color image mode is set to output image in two colors, red and black, the control unit switches between lighting the red light source and the green and blue light sources. The image reading device according to feature 1.

3. The control unit limits the selectable two colors in the two-color image mode, and switches to the full-color mode when it detects a color other than the two limited colors. The image reading device according to feature 1 or 2.

4. The control unit changes the illumination duty cycle of the light source to be emitted. The image reading device according to feature 1 or 2.

5. The control unit shall, in the two-color image mode, turn on the light source twice. The image reading device according to feature 1 or 2.

6. The reading unit reads the original document using an image sensor. The image reading device according to feature 1 or 2.

Images