JP2010273302A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus which can discriminate a fluorescence area included in an image with high sensitivity. <P>SOLUTION: The image reading apparatus 1-1 includes an irradiation means 10 having an R-color light source, a G-color light source and a B-color light source, and an imaging means 20 which has sensitivity to light of any of the light sources and outputs color image data of the medium based upon light from the medium S, and outputs color image data based upon RGB color data of the imaging means. Further, the image reading apparatus includes a fluorescence image data generation means of generating fluorescence image data including the fluorescence area emitting light of a second wavelength range of the visible range different from a first wavelength range different from R-color light of the visible light on receiving light of the first wavelength range, and optical sensors 51 and 52 which can receive the light from the medium, output signals indicating reception states of the light from the medium, and have higher sensitivity to the light of the second wavelength range than to the light of the first wavelength range, and the fluorescence image data generation means generates the fluorescence image data based upon the outputs of the optical sensors when the light source which emits the light of the first wavelength range is turned on. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image reading apparatus, and in particular, an image reading apparatus including an irradiating unit having an R color light source, a G color light source, and a B color light source, and an imaging unit having sensitivity to light of any of the light sources. About.

  Conventionally, a technique for discriminating a fluorescent region included in an image formed on a medium to be read is known. For example, in Patent Document 1, among a plurality of color signals obtained by reading a color document, the r signal is equal to or higher than a first threshold value, the g signal is equal to or higher than a second threshold value, and the b signal is equal to or lower than a third threshold value. There is disclosed a color image processing apparatus that determines a fluorescent color when (first and second thresholds> third threshold).

Japanese Patent No. 3347477

  Here, in the determination method of Patent Document 1, a threshold value is set between the color signal value of a color that is not a fluorescent color and the value of the color signal of the fluorescent color. It may not be possible to increase it.

  An object of the present invention is to provide an image reading apparatus capable of discriminating a fluorescent region included in an image formed on a medium to be read with high sensitivity.

  An image reading apparatus according to the present invention includes an R color light source that emits R color light, a G color light source that emits G color light, and a B color light source that emits B color light. And image data of an image formed on the medium based on light incident from the medium irradiated with light by the irradiation means. Imaging means for outputting, R color data that is the image data output from the imaging means when the R color light source is turned on, and the image data that is output from the imaging means when the G color light source is turned on. An image reading device that generates color image data of the image based on certain G color data and B color data that is the image data output from the imaging unit when the B color light source is turned on, Color of light Fluorescence image data that generates fluorescence image data that is image data of the image including a fluorescence region that receives light in the first wavelength region different from the first wavelength region and generates light in the second wavelength region in the visible region different from the first wavelength region A generating means, arranged to receive light from the medium irradiated with light by the irradiating means, outputting a signal indicating a light receiving state of the light from the medium, and sensitivity to light in the first wavelength range And a photosensor having a characteristic with high sensitivity to the light in the second wavelength range, and the fluorescence image data generating means is configured to turn on the light source that emits the light in the first wavelength range. The fluorescent image data is generated based on the output of the optical sensor.

  In the image reading apparatus of the present invention, the optical sensor is a G color light sensor having a higher sensitivity to G color light than a sensitivity to B color light, or an R color light sensor having a higher sensitivity to R color light than the sensitivity to G color light. And the fluorescence image data generation means is based on the output of the R color light sensor when the G color light source is turned on, or when the B color light source is turned on. The fluorescent image data is generated based on an output of a G color light sensor.

  In the image reading apparatus of the present invention, there are a plurality of the optical sensors, and a region corresponding to light received by each of the optical sensors in the main scanning direction of the medium corresponds to light received by the other optical sensors. It includes a region different from the region to be performed.

  In the image reading apparatus of the present invention, color correction based on an output of the photosensor is performed on an area corresponding to the fluorescent area of the fluorescent image data in the color image data.

  In the image reading apparatus according to the aspect of the invention, the color correction may include correcting the color in the color image data in a region corresponding to the fluorescent region of the fluorescent image data and having a spatial frequency equal to or lower than a predetermined value. It is performed on image data.

  In the image reading apparatus of the present invention, the light guide means for guiding light from the medium from the vicinity of the portion irradiated with light by the irradiation means in the medium to the optical sensor, or the light from the medium to the optical sensor It has at least any one of the condensing means which condenses, It is characterized by the above-mentioned.

  An image reading apparatus according to the present invention includes a fluorescent region that receives light in a first wavelength region different from R-colored light among visible region light and generates light in a second wavelength region in a visible region different from the first wavelength region. Fluorescent image data generating means for generating fluorescent image data that is image data of the image, and a signal that is arranged so as to be able to receive light from the medium irradiated with light by the irradiating means and that indicates a light receiving state of the light from the medium And an optical sensor having a characteristic that the sensitivity to light in the second wavelength region is higher than the sensitivity to light in the first wavelength region. The fluorescence image data generation means generates fluorescence image data based on the output of the optical sensor when the light source that emits light in the first wavelength region is turned on among the light sources of the irradiation means. Thereby, it can suppress receiving the influence of the reflected light of a 1st wavelength range, and can distinguish a fluorescence area | region with high sensitivity.

FIG. 1 is a schematic diagram showing a schematic configuration of a first embodiment of an image reading apparatus according to the present invention. FIG. 2 is a diagram showing the relative spectral characteristics of the aqueous fluorescent pen when the blue LED of the first embodiment of the image reading apparatus according to the present invention is turned on. FIG. 3 is a diagram showing the relative spectral characteristics of the aqueous fluorescent pen when the green LED of the first embodiment of the image reading apparatus according to the present invention is turned on. FIG. 4 is a diagram showing the relative spectral characteristics of the aqueous fluorescent pen when the red LED of the first embodiment of the image reading apparatus according to the present invention is turned on. FIG. 5 is a view showing a cross section including the fluorescent region extraction unit of the first embodiment of the image reading apparatus according to the present invention. FIG. 6 is an enlarged view of a main part of the first embodiment of the image reading apparatus according to the present invention. FIG. 7 is a diagram showing the spectral characteristics of the color filter of the first embodiment of the image reading apparatus according to the present invention. FIG. 8 shows a spectrum of light that passes through the color filter when the light that is emitted from the blue LED and reflected by each fluorescent pen and the white background is incident on the color filter in the first embodiment of the image reading apparatus according to the present invention. FIG. FIG. 9 is a diagram illustrating the output of the photosensor when light having passed through the filters of each color is incident on the photosensor in the first embodiment of the image reading apparatus according to the present invention. FIG. 10 is a block diagram showing the main configuration of the first embodiment of the image reading apparatus according to the present invention. FIG. 11 is a timing chart for reading an image in the first embodiment of the image reading apparatus according to the present invention. FIG. 12 is a view showing an original image to be read in the second embodiment of the image reading apparatus according to the present invention. FIG. 13 is a diagram showing the detection result of the fluorescent region when the photo sensor of the same color is used in the second embodiment of the image reading apparatus according to the present invention. FIG. 14 is a diagram showing the detection result of the fluorescent region in the second embodiment of the image reading apparatus according to the present invention when there are two photosensors of the same color. FIG. 15 is a diagram showing the detection result of the fluorescent region when the number of photosensors of the same color is four in the second embodiment of the image reading apparatus according to the present invention. FIG. 16 is a diagram showing the detection result of the fluorescent region in the second embodiment of the image reading apparatus according to the present invention when there are 11 photosensors of the same color. FIG. 17 is a timing chart for reading an image in the second embodiment of the image reading apparatus according to the present invention. FIG. 18 is a diagram illustrating an example of a relationship between a conventional image reading method and an image sensor output for fluorescent ink.

  Hereinafter, an embodiment of an image reading apparatus according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

(First embodiment)
The first embodiment will be described with reference to FIGS. 1 to 11. The present embodiment relates to an image reading apparatus including an irradiating unit having an R color light source, a G color light source, and a B color light source, and an imaging unit having sensitivity to light of any of the light sources. FIG. 1 is a schematic diagram showing a schematic configuration of a first embodiment of an image reading apparatus according to the present invention.

  In FIG. 1, reference numeral 1-1 denotes an image reading apparatus according to the present embodiment. The image reading device 1-1 includes the image reading unit 1 and a transport device (not shown). The image reading unit 1 is a contact image sensor, so-called CIS (Contact Image Sensor), optically scans an image on a sheet-like document S being conveyed, converts it into an electrical signal, and reads it as image data. Is. The image reading unit 1 includes a light source 10, a monoline sensor 20, and a lens 30.

  The light source 10 is an irradiating unit that irradiates a document S, which is a medium to be read, with visible light, a red LED (R color light source) 11 that radiates R color light, and a green LED (G color light source) that radiates G color light. 12) A three-color LED array having three-color LEDs of blue LEDs (B-color light source) 13 that emits B-color light. The light source 10 is a linear light source in which red LEDs 11, green LEDs 12, and blue LEDs 13 are repeatedly arranged in order in the main scanning direction. Each of the red LED 11, the green LED 12, and the blue LED 13 can be lit alone to irradiate the original S with monochromatic light.

  The lens 30 focuses reflected light from the document S. The lens 30 is a gradient-index (GRIN) lens having a cylindrical shape, and the optical axis is the normal direction of the document S. The lens 30 focuses the reflected light emitted from the light source 10 and reflected by the document S on the light receiving surface of the monoline sensor 20 to form an image.

  The monoline sensor 20 is, for example, a CCD (Charge Coupled Device), and a plurality of pixels receive light that is imaged (incident) through the lens 30 and converts the light into an electrical signal to read an image. It is. When the light emitted from the light source 10 and reflected by the document S is converged and imaged on the light receiving surface of the monoline sensor 20 by the lens 30, each pixel of the monoline sensor 20 converts the received light amount into an electrical signal and outputs it. . Each pixel of the monoline sensor 20 is arranged in the main scanning direction, and each reads an image of a different area on the document S. In FIG. 1, the depth direction in the drawing is the main scanning direction of the monoline sensor 20, and the horizontal direction in the drawing is the sub-scanning direction of the monoline sensor 20.

  The monoline sensor 20 is sensitive to light in the wavelength range irradiated by any LED 11, 12, 13 of the light source 10. In other words, the monoline sensor 20 is sensitive to light in the visible region from the blue light emitted by the blue LED 13 to the red light emitted by the red LED 11, and the light emitted by the red LED 11 and the green LED 12 are emitted. The color image data of the image formed on the document S can be generated based on the light and the light emitted from the blue LED 13.

  The transport device transports the document S in the transport direction that is the sub-scanning direction. The transport device includes, for example, a driving roller driven by a motor and a driven roller pressed against the driving roller, and transports the document S with the document S sandwiched between the driving roller and the driven roller.

  In the conventional image reading apparatus, the fluorescent region is determined based on the color difference or the relative output magnitude in the detection result of the image sensor. In this determination method, as described below, when the image sensor included in the image reading apparatus is a monoline sensor, it is difficult to determine fluorescence (or fluorescence cannot be determined) compared to the case of a three-line sensor. was there.

  First, the spectral characteristics of the fluorescent region will be described. The inventor of the present application paid attention to the spectral characteristics of the fluorescent region (fluorescent dye) and studied the relative spectral characteristics of the fluorescent region when irradiated with monochromatic light, and as a result, obtained the following knowledge. 2 to 4 are diagrams showing the relative spectral characteristics measured for the original of white recycled paper on which an image (fluorescent region) is written with the aqueous fluorescent pen. FIGS. 2 to 4 show a spectrum shown by an aqueous fluorescent pen of five colors (yellow, green, pink, blue, and magenta) and a spectrum shown by white recycled paper (background white). 2 to 4, the horizontal axis indicates the wavelength (nm) and the vertical axis indicates the spectral characteristic value.

  2, 3, and 4, the colors of the monochromatic light sources irradiated are different. FIG. 2 is a diagram showing the relative spectral characteristics of the aqueous fluorescent pen when the blue LED 13 that emits blue light (Blue) is turned on, and FIG. 3 is when the green LED 12 that emits green light (Green) is turned on. FIG. 4 is a diagram showing the relative spectral characteristics of the aqueous fluorescent pen when the red LED 11 that emits red light (Red) is turned on.

  As shown in FIG. 2, the base white spectrum (reference numeral 101) when the blue LED 13 is irradiated has a peak wavelength near 465 nm. Since the background white does not fluoresce, the spectrum 101 of the background white is almost the same as the spectrum of the blue LED 13 as the light source.

  Of the five color fluorescent pens, the peak wavelengths of the pink (symbol 104), blue (symbol 105), and magenta (symbol 106) fluorescent pens are the same peak wavelengths as the base white spectrum 101. There is no other peak wavelength. On the other hand, among the five color fluorescent pens, the yellow (reference numeral 102) and green (reference numeral 103) fluorescent pen spectra have the same peak wavelengths as the white base and other color fluorescent pens (pink, blue, red purple). In addition, it has peaks at different wavelengths. This shows the peak of the fluorescent component. In other words, when irradiated with blue light, the fluorescent areas of the yellow and green fluorescent pens reflect blue light and absorb part of the blue light, generating fluorescence with a longer wavelength than blue light. To do.

  In the yellow fluorescent pen spectrum 102 and the green fluorescent pen spectrum 103, the peak of reflected light (102a, 103a) near 465 nm decreases (lower than the peak of other color fluorescent pens), while 500 nm. Peaks (reference numerals 102b and 103b) due to fluorescence are seen in the vicinity. The fluorescent component having a peak near 500 nm overlaps the green wavelength region. Therefore, when the original S is irradiated with light including blue light and green light such as white light, the component of the reflected light of green light is present in the green wavelength region of the light from the original S, as will be described later. And a fluorescent component generated by absorbing blue light.

  As shown in FIG. 3, when the green LED 12 that emits green light is turned on, the spectrum of the base white (symbol 111) has a peak wavelength near 530 nm. The background white spectrum 111 is substantially the same as the spectrum of the green LED 12 as the light source. Among the five color fluorescent pens, the peak wavelengths of the yellow (reference numeral 112), green (reference numeral 113), and blue (reference numeral 115) fluorescent pens are the same peak wavelengths as the base white spectrum 111. There is no particular peak wavelength. In other words, it can be seen that the image with the yellow, green, and blue fluorescent pens does not generate fluorescence with green light.

  In the spectra 112 and 113 shown by the yellow and green fluorescent pens, the magnitude of the relative output is close to the spectrum 111 shown by the background white, and when the fluorescent component when blue light is irradiated is added to these, the background white The relative output of 1 is exceeded. For example, when both the blue LED 13 and the green LED 12 are lit, the spectrum of the yellow highlighter is the sum of the spectrum 102 of FIG. 2 and the spectrum 112 of FIG. In the wavelength range of green light, a fluorescent component (a component having a peak at 102b in FIG. 2) is added to the reflected light spectrum 112 (FIG. 2), so that the amount of light from the yellow fluorescent pen is reflected by the white background. It exceeds the amount of light.

  FIG. 18 is a diagram illustrating an example of a relationship between a conventional image reading method and an image sensor output for fluorescent ink. FIG. 18 shows image sensor outputs in three types of image reading methods for four-color fluorescent pens of yellow, green, pink, and magenta. (A1), (a2), (a3), and (a4) show the image sensor output in the image reading method by the combination of the white light source (3-wavelength white) of the cold cathode fluorescent tube (CCFL) and the 3-line sensor. . Here, the three-line sensor includes a red sensor having a red (R color) filter, a green sensor having a green (G color) filter, and a blue sensor having a blue (B color) filter. It is an image sensor. Further, (b1), (b2), (b3), and (b4) show image sensor outputs in an image reading method using a combination of a white light source of a white LED (blue LED + yellow phosphor) and a three-line sensor. In addition, (c1), (c2), (c3), and (c4) are image reading methods using a combination of a red LED, a green LED, a blue LED, and a monoline sensor (for example, the same configuration as in FIG. 1). Indicates the image sensor output.

  “Image sensor output” in FIG. 18 is a sensor of each color (blue sensor, green sensor, red) when white light is irradiated in the image reading method (a1 to a4, b1 to b4) using a three-line sensor. In the image reading method (c1 to c4) using a monoline sensor, it is the output of the monoline sensor when each color LED (blue LED, green LED, red LED) is irradiated.

  As shown in (a1) and (b1), in the 3-line sensor, the relative output of the green sensor for the yellow highlighter (relative output with respect to the white background) exceeds 1. This is because, in the green sensor, in addition to the green reflected light, the yellow fluorescent ink receives the green fluorescence generated by absorbing the blue light. The output of the green sensor is a value obtained by integrating the spectrum 102 (fluorescence component) in FIG. 2 and the spectrum 112 (reflection component) in FIG. 3 with respect to the wavelength range of green light, and this value is the background in FIG. Since it exceeds the integral value of the white spectrum 111, the relative output is greater than 1. In other words, in the image reading method using the three-line sensor, the relative output of the green sensor with respect to the image of the yellow fluorescent pen exceeds 1, so that the fluorescent region can be determined based on the output of the green sensor. The same applies to the green fluorescent pen. As shown in (a2) and (b2), the relative output of the green sensor exceeds 1, and the fluorescent region can be determined based on the output of the green sensor.

  On the other hand, as shown in (c1) and (c2), the relative output does not exceed 1 even if the output of the monoline sensor is for the fluorescent region. This is because the monoline sensor outputs an integrated value of not only the wavelength range of specific light but also the wavelength range of all light emitted from the light source 10.

  For example, when a blue fluorescent pen is irradiated with blue light (see FIG. 2), since blue light is absorbed and green fluorescence is generated, the reflected light peak 102a is lowered, and the fluorescence peak is obtained. 102b appears. With respect to such a spectrum 102, if it is a three-line sensor, blue light (reflected light) becomes the output of the blue sensor, and green light (fluorescence) becomes the output of the green sensor.

  However, the monoline sensor is sensitive to both blue light and green light. For example, a monoline sensor composed of a Si-based image sensor is sensitive to light from the near ultraviolet to the near infrared, and covers the entire visible light region. Thus, since the monoline sensor is sensitive to the wavelengths of the RGB LEDs, the value obtained by integrating the spectrum 102 of the yellow fluorescent pen from the reflected light (blue light) to the fluorescent (green light) region is blue. Output to LED. That is, in the integrated value, the decrease in the reflected light peak 102a due to the absorption of blue light and the fluorescence peak 102b due to the generation of fluorescence cancel each other. For this reason, generation | occurrence | production of fluorescence does not appear clearly in the output at the time of lighting of blue LED. On the other hand, when the green light is irradiated, the yellow fluorescent ink does not generate fluorescence, and the output of the monoline sensor (the integrated value of the spectrum 112 in FIG. 3) shows the output by simple reflected light. That is, the relative output of the monoline sensor does not exceed 1 both when the blue LED is irradiated and when the green LED is irradiated, and the fluorescent region cannot be determined from the relative output. In addition, since the fluorescence characteristic does not appear in the color difference at the output of the monoline sensor, it is not possible to determine the fluorescence from the color difference.

  As will be described below, it is difficult to distinguish fluorescence with a monoline sensor even for pink and red-violet fluorescent pens.

  In FIG. 3, the spectra of pink (symbol 114) and magenta (symbol 116) fluorescent pens have different wavelengths in addition to the peak wavelengths similar to those of white and other color fluorescent pens (yellow, green, blue). Has a peak. That is, when green light is irradiated, the pink fluorescent pen and the red-violet fluorescent pen reflect green light and absorb a part of the green light to generate fluorescence having a wavelength longer than that of the green light. In the pink fluorescent pen spectrum 114 and the red-purple fluorescent pen spectrum 116, the peak of reflected light (114a, 116a) near 530 nm decreases, while the peak due to fluorescence (114b, 116b) is observed near 580-600 nm. . The fluorescent component having a peak at 580 to 600 nm overlaps with the red wavelength region.

  As shown in FIG. 4, when the red LED 11 that emits red light is turned on, the spectrum of the base white (reference numeral 121) has a peak wavelength near 630 nm. It can be seen that in red light, none of the fluorescent pens are particularly fluorescent. Reference numeral 122 indicates yellow, 123 indicates green, 124 indicates pink, 125 indicates blue, and 126 indicates a spectrum indicated by a red-violet fluorescent pen. In the spectra 124 and 126 shown by the pink and red-violet fluorescent pens, the spectral characteristic value is close to the spectrum 121 shown by the white background, and when the fluorescent component when green light is irradiated is added, The spectral characteristic value of the white background will be exceeded. Actually, as shown in (a3), (b3), and (b4) of FIG. 18, the relative output of the red sensor of the three-line sensor with respect to the pink or magenta fluorescent pen exceeds 1. On the other hand, as shown in (c3) and (c4), the output of the monoline sensor does not exceed 1 for the fluorescent region.

  For example, a case where green light is irradiated on a pink fluorescent pen (see FIG. 3) will be described. Since green light is absorbed and red fluorescence is generated, the reflected light peak 114a is lowered and the fluorescence peak is reduced. 114b appears. For such a spectrum 114, if it is a three-line sensor, green light (reflected light) becomes the output of the green sensor, and red light (fluorescence) becomes the output of the red sensor, so that fluorescence can be discriminated. However, the monoline sensor has sensitivity to both green light and red light, and the value obtained by integrating the spectrum 114 of the pink fluorescent pen from the reflected light (green light) to the fluorescence (red light) region is green. Output to LED. In other words, the integrated value cancels the decrease in the reflected light peak 114a due to the absorption of green light and the fluorescence peak 114b due to the generation of fluorescence. For this reason, generation | occurrence | production of fluorescence does not appear clearly in the output at the time of lighting of green LED. On the other hand, when the red light is irradiated, the pink fluorescent ink does not generate fluorescence, and the output of the monoline sensor (the integrated value of the spectrum 124 in FIG. 4) indicates the output by simple reflected light. That is, the fluorescent region cannot be determined from the output of the monoline sensor when the green LED and the red LED are irradiated.

  As will be described below, the image reading apparatus 1-1 according to the present embodiment includes a fluorescent region extraction unit 50 that selectively detects a fluorescent component generated from the fluorescent region. Thereby, the fluorescent region can be distinguished with high sensitivity.

  FIG. 5 is a diagram illustrating a cross section of the image reading device 1-1 including the fluorescent region extraction unit 50. As shown in FIG. 5, the fluorescent region extraction unit 50 includes a photosensor (light sensor) 51, a color filter 52, and a light guide 53.

  The photosensor 51 outputs a signal (electric signal) corresponding to the amount of received light. The photosensor 51 of the present embodiment detects light in the visible region and outputs an electrical signal corresponding to the amount of light. The color filter 52 is a filter that allows light of a predetermined wavelength range to pass therethrough. FIG. 7 is a diagram showing the spectral characteristics of the color filter 52. In FIG. 7, symbol G1 indicates the spectral characteristic of a green filter that allows green light (G color light) to pass, and symbol R1 indicates the spectral characteristic of a red filter that allows red light (R color light) to pass. The fluorescent region extraction unit 50 includes a green filter 52g and a red filter 52r as the color filters 52.

  The photosensor 51 includes one green photosensor (G color light sensor) 51g that detects light that has passed through the green filter 52g and one red photosensor (R color light sensor) that detects light that has passed through the red filter 52r. 51r. Since the green photosensor 51g detects light that has passed through the green filter 52g, the green photosensor 51g has a higher sensitivity to G-color light than that to B-color light. That is, the photosensor 51 and the green filter 52g constitute an optical sensor having a characteristic that is higher in sensitivity to the G color light than the sensitivity to the B color light. Since the red photosensor 51r detects light that has passed through the red filter 52r, the red photosensor 51r has a higher sensitivity to the R color light than the sensitivity to the G color light. That is, the photosensor 51 and the red filter 52r constitute an optical sensor having a characteristic that is higher in sensitivity to R color light than that in G color light. Note that, instead of using a color sensor, the photosensor 51 itself has a characteristic that the sensitivity to the G color light is higher than the sensitivity to the B color light, or the characteristic that the sensitivity to the R color light is higher than the sensitivity to the G color light. You may make it have. These spectral characteristics G1 and R1 can be the same as the spectral characteristics of the filters included in the green sensor and red sensor of a three-line sensor, for example. 7 indicates an example of a spectral characteristic of a blue filter that allows blue light (B color light) to pass therethrough.

  The light guide 53 is a light guide that guides light from the document S to the photosensor 51. FIG. 6 is an enlarged view of a main part of the image reading apparatus 1-1. The photosensor 51 is arranged in the mirror reflection direction of the light emitted from the light source 10. The light source 10 irradiates the document S with light from a direction oblique to the normal direction of the document S, and the light A 1 irradiated from the light source 10 is diffusely reflected by the document S. Of the diffusely reflected light, the light reflected in the normal direction of the document S is converged and imaged on the light receiving surface of the monoline sensor 20 by the lens 30 as shown in FIG. Further, the light A <b> 2 reflected in the specular reflection direction enters the light guide 53. As described above, by using the light reflected in the direction different from the direction reflected toward the lens 30, the light guide 53 and the photosensor 51 can be arranged using the space effectively.

  The light guide 53 is formed with an incident surface 53b orthogonal to the traveling direction of the light A2 reflected in the specular reflection direction on the document S, and the light A2 reflected in the specular reflection direction on the document S from the incident surface 53b. The light enters the light guide 53. The incident surface 53b is provided in the vicinity of a reading target portion irradiated with light on the document S. That is, the light guide 53 guides the light from the vicinity of the portion of the document S irradiated with light from the light source 10 to the photosensor 51. The photosensor 51 receives light from the document S that has been irradiated with light from the light source 10 via the light guide 53.

  The light that has entered the light guide 53 travels by being totally reflected in the light guide 53 as indicated by reference numeral A3. A lens portion 53 a is formed in a portion of the light guide 53 that faces the photosensor 51. The lens portion 53 a has a convex shape that protrudes toward the photosensor 51, and is formed in a shape that can collect the light A <b> 3 that has traveled through the light guide 53 onto the photosensor 51. The light (line image) reflected by the image on the reading line of the document S and passing through the light guide 53 is condensed on the photosensor 51 by the lens unit 53a. In other words, the light from the light source 10 reflected at each location on the reading line of the document S is collected on one photosensor 51. As a result, reflected light in a wide range in the main scanning direction is collected on one photosensor 51, and based on the output of the photosensor 51, it can be determined whether or not a fluorescent region exists on the reading line. .

  The color filter 52 is disposed between the lens portion 53 a of the light guide 53 and the photosensor 51. The green filter 52g is disposed between the lens unit 53a and the green photosensor 51g, and among the light collected from the lens unit 53a to the green photosensor 51g, the light that has passed through the green filter 52g is green. Is incident on the green photosensor 51g and detected by the green photosensor 51g. Similarly, the red filter 52r is disposed between the lens unit 53a and the red photosensor 51r, and the light collected from the lens unit 53a to the red photosensor 51r has passed through the red filter 52r. Light enters the red photosensor 51r and is detected by the red photosensor 51r.

  In the present embodiment, as described below, based on the output of the green photosensor 51g when the blue LED 13 is irradiated or based on the output of the red photosensor 51r when the green LED 12 is irradiated, Perform fluorescence discrimination. According to this method, the fluorescence component generated from the fluorescence region can be extracted to perform fluorescence discrimination, and the sensitivity of fluorescence discrimination can be increased.

  FIG. 8 is a diagram showing a result of multiplying the relative spectral characteristics (see FIG. 2) when the blue LED 13 is irradiated and the spectral characteristics of each color of the color filter 52 shown in FIG. 7 for each wavelength. That is, FIG. 8 is a diagram illustrating a spectrum of light that passes through the color filter 52 when light emitted from the blue LED 13 and reflected by each fluorescent pen and the white background is incident on the color filter 52.

  In FIG. 8, reference numerals 201, 202, and 203 denote a product of the base white spectrum 101 and the blue filter characteristic B 1 when the blue LED 13 is irradiated, a product of the yellow fluorescent pen spectrum 102 and the blue filter characteristic B 1, respectively. The product of the spectrum 103 of the green highlighter and the blue filter characteristic B1 is shown. Reference numerals 211, 212, and 213 denote a product of the base white spectrum 101 and the green filter characteristic G 1 when the blue LED is irradiated, a product of the yellow fluorescent pen spectrum 102 and the green filter characteristic G 1, and green The product of the spectrum 103 of the highlighter and the green filter characteristic G1 is shown. Reference numerals 221, 222, and 223 denote a product of the base white spectrum 101 and the red filter characteristic R1 when the blue LED is irradiated, a product of the yellow fluorescent pen spectrum 102 and the red filter characteristic R1, and a green fluorescent pen, respectively. The product of the spectrum 103 and the red filter characteristic R1 is shown.

  FIG. 9 is a diagram showing values obtained by integrating the products of the spectrum and the filter characteristics shown in FIG. 8, and shows the output of the photosensor 51 when light having passed through the filters of the respective colors is incident on the photosensor 51. ing.

  As shown in FIG. 9, when the red filter 52r is passed, there is almost no output in any of the base white, the yellow fluorescent pen, and the green fluorescent pen. This is because reflected light (wavelength 450 to 480 nm) and fluorescence (wavelength 500 to 550 nm) when the blue LED 13 is irradiated hardly pass through the red filter 52r.

  In the output through the green filter 52g, the output to the yellow fluorescent pen and the output to the green fluorescent pen are larger than the output to the white background. This is because the green filter 52g restricts the passage of blue reflected light and extracts a green fluorescent component. In this way, the output exceeds the background white only in the fluorescent region, and if the image is made of normal ink that does not fluoresce, the output does not exceed the background white output, and the output of the background white Maximum. Therefore, if there is an output larger than the white background, it can be determined that the region is a fluorescent region. In this determination, the fluorescence region can be determined with higher sensitivity as the difference between the background white output and the fluorescence region output is larger. As shown in FIG. 9, the yellow fluorescent pen has about 6 times the output of the background white, and the green fluorescent pen has about 3 times the output of the background white. . Therefore, it is possible to discriminate an image (fluorescent region) with a yellow or green fluorescent pen with high sensitivity.

  When the blue filter is passed, the output of the background white is larger than the output of the yellow fluorescent pen and the output of the green fluorescent pen. The yellow and green fluorescent pens absorb blue light, which is excitation light, and generate green fluorescence, so the relative output of blue light decreases. Therefore, the white background is the brightest, similar to the reflection characteristic of non-fluorescent ink. For this reason, when the blue LED 13 is irradiated, the output through the blue filter cannot distinguish between the output of the image by the non-fluorescent ink and the output of the fluorescent region. Therefore, the most suitable condition for reading the fluorescent region as an image when irradiating blue light is the condition of (blue LED 13 irradiation−green filter 52g output). That is, in order to selectively extract the fluorescent component, it is sufficient to use the output of a filter that transmits light having a wavelength different from that of the excitation light to be irradiated and a wavelength corresponding to the wavelength range of the fluorescence.

  In the image reading apparatus 1-1 of the present embodiment, a fluorescent region such as yellow or green that emits green fluorescence is determined based on the output of the green photosensor 51 g that has passed through the green filter 52 g when the blue LED 13 is irradiated. To do. In other words, yellow and green fluorescent regions that receive B-color light (light in a first wavelength range different from R-color light) and generate visible G-color light (fluorescence that is light in the second wavelength range) different from B-color light. Based on the output of the green photosensor 51g when the blue LED 13 is turned on, fluorescent image data that is image data including a fluorescent region is generated. As a result, the yellow and green fluorescent regions included in the image to be read can be distinguished with high sensitivity.

  In addition, as described with reference to FIG. 3, the fluorescent component of the pink and red-violet fluorescent pen when the green LED 12 is irradiated has a wavelength range of 580 to 600 nm that overlaps with the red wavelength range (red filter characteristic R1). Have a peak. On the other hand, in the base white spectrum 111 when the green LED 12 is irradiated, the overlap size with the red filter characteristic R1 is smaller than that of the pink or red-violet fluorescent pen. Accordingly, in the output of the red photosensor 51r that has passed through the red filter 52r when the green LED 12 is irradiated, the value of the pink or red-violet fluorescent pen is larger than the value of the white background.

  In the present embodiment, based on the output of the red photosensor 51r when the green LED 12 is irradiated, a fluorescent region that emits red fluorescence, such as pink or red-violet fluorescent ink, is determined. In other words, a pink or red-violet fluorescent region that receives G-color light (light having a first wavelength range different from that of R-color light) and generates visible R-color light (fluorescence that is light in the second wavelength range) that is different from the G-color light. , Based on the output of the red photosensor 51r when the green LED 12 is turned on, fluorescent image data that is image data including a fluorescent region is generated. As a result, the pink or reddish purple fluorescent region included in the image to be read can be distinguished with high sensitivity.

  The fluorescent image data obtained in this way is image data of the entire image of the document S including the fluorescent region. In the fluorescence image data, the fluorescent region is bright (the amount of light is large), and the region other than the fluorescent region is dark (the amount of light is small, for example, the amount of light is 0). As described above, the fluorescence image data is generated as data obtained by separating only the fluorescent region based on the red and green fluorescent components (light in the second wavelength region) from the fluorescent region of the document S. In the present embodiment, based on the output of the photosensor 51, it is determined only whether the detection target region is a fluorescent region. That is, the generated fluorescence image data is generated as binary image data indicating whether it is a fluorescent region or a region other than the fluorescent region.

  FIG. 10 is a block diagram illustrating a main configuration of the image reading apparatus 1-1. The image reading apparatus 1-1 is provided with a control unit 40. The control unit 40 includes an image input unit 41, a comparator 42, and an output synchronization circuit 43.

  The image input unit 41 inputs an electric signal output from the monoline sensor 20, amplifies it, performs A / D conversion, and sends it to the output synchronization circuit 43. The image input unit 41 reads the electrical signals of the pixels sequentially output from the monoline sensor 20 and acquires line data regarding the image on the reading line of the document S. The image input unit 41 acquires line data of three colors corresponding to each LED of the light source 10 that is sequentially turned on. Specifically, when the red LED 11 is turned on, the output captured by the monoline sensor 20 is read as red line data (R color data) that is red component data related to an image on the line, and the green LED 12 is turned on. The output of the monoline sensor 20 when it is on is captured as green line data (G color data), and the output of the monoline sensor 20 when the blue LED 13 is lit is captured as blue line data (B color data). Each captured line data is sent from the image input unit 41 to the output synchronization circuit 43.

  The output of the comparator 42 is switched according to the magnitude relationship between the output of the photosensor 51 and the threshold value. The comparator 42 outputs a fluorescence signal ON when the output of the photosensor 51 is larger than a predetermined threshold value. On the other hand, when the output of the photosensor 51 is smaller than the threshold, the comparator 42 outputs a fluorescence signal OFF. The threshold value is set based on the output of the photosensor 51 when light reflected by the non-fluorescent white reference plate passes through the color filter 52 and enters the photosensor 51. For example, the threshold for the green photosensor 51g will be described. When the blue LED 13 is irradiated, the green photosensor 51g is reflected by the white reference plate, passes through the green filter 52g, and enters the green photosensor 51g. A threshold value is set based on the output value.

  The output synchronization circuit 43 synchronizes and outputs the line data sent from the image input unit 41 and the fluorescence signal sent from the comparator 42. As will be described with reference to FIG. 11, the line data sent from the image input unit 41 is delayed from the line sequential lighting of the light source 10 by the time required for the charge transfer of the monoline sensor 20. On the other hand, the output of the photosensor 51 is output simultaneously with the line sequential lighting of the light source 10. The output synchronization circuit 43 synchronizes the output of the monoline sensor 20 and the output of the photosensor 51, and outputs them as an image output and a fluorescence signal, respectively.

  FIG. 11 is a timing chart relating to reading of an image by the image reading device 1-1 of the present embodiment. FIG. 11 shows an operation of discriminating the fluorescent region of the fluorescent ink that generates red fluorescence in parallel with the image reading by the monoline sensor 20.

  11, (a) is an LED that is turned on in the light source 10, (b) is the output of the monoline sensor 20 output from the image input unit 41, and (c) is the output of the red photosensor 51 r of the photosensor 51. , (D) show the fluorescence signals synchronized with the output of the monoline sensor 20 by the output synchronization circuit 43, respectively.

  When reading an image, the light source 10 sequentially repeats (single color) lighting of the red LED 11, (single color) lighting of the green LED 12, and (single color) lighting of the blue LED 13. The output indicating the imaging result of the monoline sensor 20 during the period P2 during which the green LED 12 is lit is transferred by the monoline sensor 20 during the period P3 during which the next blue LED 13 is lit, as indicated by the arrow Y1. Sent to the unit 41. In this way, the output of the monoline sensor 20 is output with a delay corresponding to the line-sequential lighting period (one cycle) of each LED in the light source 10.

  On the other hand, the output of the photosensor 51 is output simultaneously with the lighting of the LED. When the green LED 12 is turned on in the period P2, the red photosensor 51r is simultaneously irradiated from the green LED12, reflected by the document S, passes through the light guide 53 and the red filter 52r, and enters the red photosensor 51r. The light detection result X1 is output. The comparator 42 sends a fluorescent signal ON to the output synchronization circuit 43 when the detection result X1 is larger than the threshold value. As indicated by an arrow Y2, the output synchronization circuit 43 synchronizes the fluorescence signal ON based on the detection result X1 with the output of the monoline sensor 20, and outputs it as the fluorescence signal ON in the period P3. Note that the output X2 of the red photosensor 51r when the red LED 11 is turned on shows only red reflected light and does not include a fluorescent component, and therefore is invalid even if the value exceeds the threshold. Further, the output of the red photosensor 51r when the blue LED 13 is turned on is also invalidated.

  Although not shown, the same applies to the method of discriminating the fluorescent region by the green photosensor 51g. When the output of the green photosensor 51g when the blue LED 13 is lit exceeds the threshold value, the comparator 42 outputs the fluorescence signal ON. Is done. The output synchronization circuit 43 outputs the fluorescence signal ON sent from the comparator 42 in synchronization with the imaging result of the monoline sensor 20 based on the light emitted from the blue LED 13.

  The control unit 40 synthesizes the color image line data output from the output synchronization circuit 43 to generate color image data, and generates fluorescence image data based on the fluorescence signal. Specifically, the control unit 40 has a storage unit (not shown) that temporarily stores each line data (R color data, G color data, and B color data). Generate and output image data. Further, the control unit 40 generates fluorescence image data from the fluorescence line data based on the fluorescence signal. In the present embodiment, the control unit 40 has a function as fluorescence image data generation means. In addition, by outputting each line data and fluorescence signal from the output synchronization circuit 43 to a data processing device (PC or the like) connected to the image reading device 1-1, the color image data or fluorescence of a normal image is output in the data processing device. Image data or the like may be generated.

  As described above, according to the image reading apparatus 1-1 of the present embodiment, the fluorescent region can be determined with high sensitivity based on the output of the photosensor 51 of the fluorescent region extraction unit 50. Even in the case where fluorescence from the fluorescent region is incident, the fluorescent region can be discriminated with high sensitivity in the image reading apparatus 1-1 including the monoline sensor 20 that does not easily appear as a color difference or a relative output. Further, since a special light source 10 switching method for distinguishing the fluorescent region and a special light source such as ultraviolet rays are not required, the distinction of the fluorescent region can be performed without affecting the image reading by the monoline sensor 20. It can be carried out.

  Based on the separated fluorescent region (fluorescent signal), the reading region surrounded by the fluorescent region is cropped, or the character information of the color image data (image data read by the monoline sensor 20) overlapping the fluorescent image data is subjected to OCR processing. It is possible to construct an image reading system. In this embodiment, since the fluorescent component in the fluorescent region can be selectively extracted, the fluorescent region can be distinguished with high sensitivity. Therefore, the accuracy of the image reading system that performs image processing based on the fluorescent region can be improved. In addition, since the fluorescent component can be acquired as independent fluorescent image data separated from the normal image, various image processing for combining the fluorescent component and the normal image can be performed. For example, an image in which an area marked with a highlighter is emphasized can be generated.

(First modification of the first embodiment)
A first modification of the first embodiment will be described. In the first embodiment, the light reflected by the document S is guided to the photosensor 51 by the light guide 53, but the means for condensing the light on the photosensor 51 is not limited to this. For example, instead of the light guide 53, a lens (light condensing means) that condenses the light reflected by the document S on the photosensor 51 may be provided.

(Second modification of the first embodiment)
A second modification of the first embodiment will be described. In the first embodiment, light in a predetermined wavelength range is selectively passed by the color filter 52 disposed between the light guide 53 and the photosensor 51. Instead, the light guide 53 The device itself may also serve as the color filter 52.

(Second Embodiment)
The second embodiment will be described with reference to FIGS. In the second embodiment, only differences from the first embodiment will be described.

  In the first embodiment, one red photosensor 51r and one green photosensor 51g are provided. However, in the image reading apparatus 1-2 according to the present embodiment, the red photosensor 51r and the green photosensor 51g are provided. A plurality of 51g are arranged. Thereby, it is possible to determine which region in the main scanning direction (on the reading line) is the fluorescent region.

  The relationship between the number of photosensors 51 and the detection resolution of the fluorescent region in the main scanning direction will be described with reference to FIGS. FIG. 12 shows the original image S to be read, FIG. 13 shows the detection result of the fluorescent region when there is one photosensor 51 of the same color, and FIG. 14 shows the detection result of the fluorescent region when there are two photosensors 51 of the same color. 15 shows the detection result of the fluorescent region when the number of photosensors 51 of the same color is four, and FIG. 16 shows the detection result of the fluorescent region when there are eleven photosensors 51 of the same color.

  In FIG. 12, a symbol F indicates a fluorescent region where a fluorescent image is formed on the document S. The fluorescent region F is in the center of the document S in the main scanning direction. Further, Pic1 to Pic4 in FIGS. 13 to 16 indicate the fluorescence image data of the detection result, and F1 to F4 indicate the fluorescence region of the determination result. When the number of the photosensors 51 shown in FIG. 13 is one, it is possible to determine whether or not the fluorescent region F exists on the line in the main scanning direction, but which region in the main scanning direction is the fluorescent region F. It cannot be determined whether there is any. Therefore, the width in the main scanning direction is uniform in the fluorescent region F1 as the discrimination result. For example, the entire width in the main scanning direction is determined as the fluorescent region.

  When two photosensors 51 are arranged in the main scanning direction as shown in FIG. 14, reflected light from different regions in the main scanning direction of the document S is incident on each photosensor 51. Light from one side region S1 of the document S in the main scanning direction enters one of the photosensors 51 511, and light from the other side region S2 enters the other 512 of the photosensors 51. Note that the detection target areas of the photosensors 511 and 512 may partially overlap in the main scanning direction. In other words, in the main scanning direction, the region corresponding to the light received by one of the photosensors 51 511 may include a region different from the region corresponding to the light received by the other 512 of the photosensor 51. As described above, each of the photosensors 511 and 512 receives light from different regions in the main scanning direction, so that the region S1 on one side in the main scanning direction based on the detection result of one of the photosensors 511. And the fluorescence discrimination of the region S2 on the other side in the main scanning direction can be performed based on the detection result of the other 512 of the photosensor 51. Since the fluorescent region F is in the center of the document S in the main scanning direction, both the photosensors 511 and 512 detect fluorescence. Therefore, the fluorescent region F2 as a discrimination result is applied to both the regions S1 and S2.

  When four photosensors 51 are arranged in series in the main scanning direction as shown in FIG. 15, the document S can be divided into four in the main scanning direction, and fluorescence can be determined for each region. As a result, a fluorescent region F3 as a result of discrimination obtained by appropriately discriminating the central portion of the document S in the main scanning direction as the fluorescent region is obtained.

  Similarly, when 11 photosensors 51 are arranged in the main scanning direction as shown in FIG. 16, the document S can be divided into 11 in the main scanning direction, and fluorescence can be determined for each region. The fluorescent region F4 of the discrimination result is closer to the fluorescent region F of the original document S. In this way, by increasing the number of photosensors 51, the detection resolution of the fluorescent region in the main scanning direction can be improved, and the reproducibility of the fluorescent region F can be improved.

  Regarding the arrangement of the red photosensors 51r and the green photosensors 51g, for example, the red photosensors 51r and the green photosensors 51g are alternately and serially arranged in the main scanning direction. The red filter 52 r and the green filter 52 g are alternately arranged in the main scanning direction in accordance with the arrangement of the photosensors 51.

  FIG. 17 is a timing chart relating to reading of an image by the image reading device 1-2 of the present embodiment. FIG. 17 shows a timing chart when two red photosensors 51r are arranged in the main scanning direction (see FIG. 14).

  17, (a) is an LED that is turned on by the light source 10, (b) is an output of the first red photosensor 511r that detects light from the region S1 on one side of the original S in the main scanning direction, and (c) ) Is the output of the second red photosensor 512r for detecting light from the other side region S2 in the main scanning direction of the document S, and (d) is the fluorescence synchronized with the output of the monoline sensor 20 by the output synchronization circuit 43. Each signal is shown.

  In the period P2 in which the green LED 12 is turned on in the light source 10, the first red photosensor 511r and the second red photosensor 512r are from the document S that has received light emitted from the green LED 12 simultaneously with the lighting of the green LED 12. The incident light detection results X3 and X4 are respectively output. The output synchronization circuit 43 outputs the fluorescence signal ON based on the output X3 of the first red photosensor 511r in synchronization with the output of the pixel corresponding to the region S1 on one side among the pixels of the monoline sensor 20, and the other side. The fluorescence signal ON based on the output X4 of the second red photosensor 512r is output in synchronization with the output of the pixel corresponding to the region S2. In other words, the output synchronization circuit 43 determines that the data output at the same time in the image data of the normal image read by the monoline sensor 20 and the fluorescent signal based on the output of the photosensor 51 are for the same area of the document S. Thus, the normal image data and the fluorescence signal are synchronized.

  In the case where a plurality of photosensors 51 are arranged in the main scanning direction and the reflected light from the document S is condensed on the photosensor 51 by a lens instead of the light guide 53, a lens is provided for each photosensor 51. (Microlens) may be arranged. When there are a large number of photosensors 51, the cost can be reduced by using a multi-lens system instead of the light guide 53. On the other hand, when the reflected light is guided to the photosensor 51 by the light guide 53, the image reading apparatus can be made compact. The light guide 53 is particularly effective when the number of photosensors 51 is small.

(Third embodiment)
A third embodiment will be described. In the third embodiment, only differences from the above embodiments will be described.

  In the present embodiment, color conversion processing is performed on the color image data from the monoline sensor 20 for the determined fluorescent region. Thereby, the fluorescence characteristic can be appropriately reflected in the color image data.

  As described with reference to FIG. 18, when an image is read by a combination of the monoline sensor 20 and the switching of the three-color light source, even if there is a fluorescent region, a color difference is difficult to occur. For example, when a blue LED 13 is irradiated to yellow fluorescent ink, green fluorescence is generated. However, at the output of the monoline sensor 20, this green fluorescent component is output as blue light data. For this reason, in the obtained image data, the fluorescence characteristics may not always be properly reflected.

  In the present embodiment, color conversion processing is performed on the color image data read by the monoline sensor 20 for the area determined as the fluorescent area. Specifically, color conversion processing (color correction processing) is performed on color image data of pixels having a color difference with respect to the background based on the type (characteristics) of the color filter 52 of the photosensor 51 and the output of the photosensor 51. The

  This color conversion process is executed by the control unit 40, for example. The control unit 40 determines whether or not a pixel in a region corresponding to the fluorescent region of the fluorescent image data in the color image data has a color difference compared to the background. The control unit 40 is an output when the monoline sensor 20 outputs color data of the target pixel, which is an output when the red LED 11 is exposed with the R color light, and an output when the green LED 12 is exposed with the G color light. The color difference between the green output and the blue output that is output when the blue LED 13 is exposed to the B color light is calculated. When the calculated color difference is different from the color difference of the background (for example, the background white) (has a color difference with the background), color conversion processing is performed so that the color difference is conspicuous.

  For example, when a fluorescent region is determined based on the output of the green photosensor 51g, the region is considered to be a fluorescent region with fluorescent ink that generates green fluorescence (fluorescent ink such as yellow or green). When the pixel data in this region has a color difference indicating yellow with respect to the background, the control unit 40 increases yellow by increasing the green output and decreasing the blue output. Thereby, the fluorescence characteristic of the yellow fluorescent ink can be appropriately reflected in the color image. In this color conversion, the correction intensity of the color conversion process can be made variable based on the output of the green photosensor 51g. For example, the correction intensity can be increased as the output of the green photosensor 51g increases.

  Further, in the pixel data of the region determined as the fluorescent region based on the output of the green photosensor 51g, when there is a color difference indicating green with respect to the background, the green output is increased, and the blue output and the red output are decreased. Can strengthen the green color. Thereby, the fluorescence characteristic of the green fluorescent ink can be appropriately reflected in the color image.

  Color conversion processing can also be performed on pixel data in a region determined to be a fluorescent region based on the output of the red photosensor 51r. In this case, by lowering the green output and increasing the red output, the fluorescence characteristics of the fluorescent ink that emits red fluorescence such as pink and magenta can be appropriately reflected in the color image.

  In addition, it is desirable not to perform the color conversion process when the pixel data has no color difference with the background or the color difference with the background is small even in the area corresponding to the fluorescent area in the color image data. . When the pixel data has no color difference with the background or the color difference with the background is small, the color is light or the color is detected within the error range. In such a case, if the color conversion process is executed, colors that are invisible or hardly visible to the naked eye will be emphasized more than necessary, so it is desirable not to execute the color conversion process.

  Further, in the color image data, it is not determined whether all pixels in the region corresponding to the fluorescent region have a color difference with respect to the background, but a determination target for determining whether there is a color difference with respect to the background. You may limit to the image with a low spatial frequency. This is because marking with a highlighter is often a low spatial frequency such as drawing a thick line on a character string or surrounding a text area with a thick frame line. By determining whether there is a color difference only for an image with a low spatial frequency, it is possible to reduce the load of image processing. Further, it is possible to suppress unnecessary color conversion processing on an image that does not generate fluorescence. The threshold (predetermined value) of the spatial frequency of the image to be determined whether there is a color difference with respect to the background is set based on, for example, the spatial frequency of a thick straight line or a frame line drawn with a highlighter pen.

1-1 Image Reading Device 1 Image Reading Unit 10 Light Source 11 Red LED
12 Green LED
13 Blue LED
DESCRIPTION OF SYMBOLS 20 Monoline sensor 30 Lens 40 Control part 41 Image input part 42 Comparator 43 Output synchronous circuit 50 Fluorescence area extraction part 51 Photo sensor 51g Photo sensor for green 51r Photo sensor for red 52 Color filter 52g Green filter 52r Red filter 53 Light guide 53a Lens part 53b Incident surface F Fluorescent area S Document

Claims (6)

An irradiating means for irradiating a medium to be read with an R color light source for irradiating R color light, a G color light source for irradiating G color light, and a B color light source for irradiating B color light;
Imaging means that is sensitive to the light of any of the light sources and outputs image data of an image formed on the medium based on light incident from the medium irradiated with light by the irradiation means. R color data that is the image data output from the imaging unit when the R color light source is lit, G color data that is the image data output from the imaging unit when the G color light source is lit, and An image reading device that generates color image data of the image based on B color data that is the image data output from the imaging unit when a B color light source is turned on,
Fluorescence that is image data of the image including a fluorescent region that receives light in a first wavelength region different from the R color light in the visible region and generates light in a second wavelength region that is different from the first wavelength region. Fluorescence image data generation means for generating image data;
Arranged so as to be able to receive light from the medium irradiated with light by the irradiation means, and outputs a signal indicating a light receiving state of the light from the medium, compared with the sensitivity to the light in the first wavelength range An optical sensor having a characteristic of high sensitivity to light in the second wavelength range,
The fluorescence image data generation unit generates the fluorescence image data based on an output of the photosensor when the light source that emits light in the first wavelength range is turned on. . The image reading apparatus according to claim 1,
The optical sensor has at least one of a G color light sensor having a higher sensitivity to G color light than a sensitivity to B color light and an R color light sensor having a higher sensitivity to R color light than the sensitivity to G color light. ,
The fluorescent image data generating means is based on the output of the R color light sensor when the G color light source is turned on, or based on the output of the G color light sensor when the B color light source is turned on. An image reading apparatus that generates fluorescence image data. The image reading apparatus according to claim 1 or 2,
There are a plurality of the optical sensors, and in the main scanning direction of the medium, an area corresponding to light received by each optical sensor includes an area different from an area corresponding to light received by another optical sensor. An image reading apparatus. The image reading apparatus according to any one of claims 1 to 3,
An image reading apparatus, wherein color correction based on an output of the photosensor is performed on a region of the color image data corresponding to the fluorescent region of the fluorescent image data. The image reading apparatus according to claim 4.
The color correction is performed on the color image data in the color image data in a region corresponding to the fluorescent region of the fluorescent image data and having a spatial frequency equal to or lower than a predetermined value. An image reading apparatus. In the image reading device according to any one of claims 1 to 5,
At least a light guiding unit that guides light from the medium from a vicinity of a portion irradiated with light by the irradiation unit in the medium, or a light collecting unit that collects light from the medium on the optical sensor. An image reading apparatus comprising any one of the above.

Images