JP2009171376A - Illumination unit, image reader with the same, and image forming apparatus equipped with the unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination unit which suppresses color-tone variations in a plurality of light sources, using a simple constitution, and to provide an image reader, equipped with the same and image forming apparatus equipped with the same. <P>SOLUTION: In the illumination unit 62, in which a plurality of light sources 76 irradiating a document surface 64a with illumination light are arrayed into a line shape, between neighboring light sources 76, a regulation member 88 is disposed which regulates the emission angle α1 of illumination light, emitted from the light sources 76 directed toward the document surface 64a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an illumination unit in which a plurality of light sources are arranged in a line, an image reading apparatus including the same, and an image forming apparatus including the same.

  Conventionally, an image reading apparatus irradiates a document surface on which a document is placed on a contact glass with illumination light from a light source, and inputs reflected light from the document to a CCD (Charge Coupled Devices) image sensor. Image information is converted into a digital electrical signal and read. As a light source, a tubular light source such as a xenon lamp or a cathode ray lamp is adopted. However, in recent years, an LED (Light Emitting Diode) having a low price and high illuminance is used as a light source in an image reading apparatus. White light of a light source using a light emitting diode is realized by adding a plurality of lights. Specifically, the blue light from the light emitting element of the light emitting diode has passed through the phosphor in the red to green wavelength band obtained as fluorescence by passing through the phosphor in the yellow wavelength band. The blue color is combined and emits white light. Here, since the proportion of blue light transmitted through the phosphor slightly varies depending on the amount of blue light emitted and the distance of the blue light passing through the phosphor, the color tone such as spectral characteristics or chromaticity is different for each white light emitting diode. You will end up with something different. When image reading is performed without taking into account the color tone variation of this light source, color tone variations such as pure white, yellowish white, blueish white, etc. occur, and color tone variations also occur for each light source module as the illumination means. Reading quality may be degraded.

  Therefore, in Patent Document 1, a light source module in which a plurality of light sources that irradiate a subject image such as a document is arranged, a photoelectric conversion unit that reads the subject image irradiated by the light source module and outputs the read signal, and a plurality of light sources Rank setting means for setting the tone rank of the light source, signal correction means for correcting the signal output from the photoelectric conversion means, and control means for switching the matrix color calculation parameters by the signal correction means in accordance with the tone rank. Have. As a result, the difference in color tone can be absorbed, and any of a plurality of light source modules can read a color original image with the same color tone.

However, in the above-described conventional technique, the operator sets the color tone rank of the light source module from the operation panel or the like, and the operation becomes complicated. Alternatively, instead of setting the color tone rank from the operation panel or the like, there is a method in which the color tone rank information is set in advance magnetically, electrically, or optically for each light source module. Since the color tone rank information is set for each light source module, it takes time, and the correction calculation to be controlled is complicated based on the setting information. As a result, there has been a problem that the cost of assembling modules such as software development and measurement / setting is increased.
JP 2003-8911 A (paragraph [0110]-[0115], FIG. 16)

  The present invention has been made to solve the above-described problems, and has a simple configuration and an illumination unit that suppresses variations in color tone of a plurality of light sources, an image reading apparatus including the illumination unit, and an image including the illumination unit. An object is to provide a forming apparatus.

  In order to achieve the above object, the present invention provides an illumination unit in which a plurality of light sources that irradiate illumination light toward a document surface are arranged in a line, and between the adjacent light sources, the light source faces the document surface. A restriction member for restricting the emission angle of the emitted illumination light is provided.

  According to this configuration, the illumination light emitted from the plurality of light sources is restricted from being irradiated on the document surface with light having an angle exceeding a predetermined emission angle.

  In the second aspect of the invention, the color difference of the illumination light according to the emission angle in the chromaticity coordinate X of the XY coordinate system is ΔX, and the illumination according to the emission angle in the chromaticity coordinate Y of the XY coordinate system. When the color difference of light is represented by ΔY, the restriction member is disposed so that illumination light having ΔX and ΔY of 0.02 or less illuminates the original surface continuously in the light source arrangement direction. It is said. According to this configuration, the original surface in the light source array direction is continuously illuminated with illumination light having color differences ΔX and ΔY of 0.02 or less.

  The invention according to claim 3 is provided with a substrate for holding the light source, and the regulating member is characterized in that the one end portion is held by the substrate and the other end portion intersects with the emission angle. . According to this configuration, the light from the light source exceeding the predetermined emission angle is restricted from irradiating the document surface.

  According to a fourth aspect of the present invention, the restricting member includes a reflecting surface that reflects light from the light source between the one end and the other end. According to this configuration, when light from the light source exceeding the emission angle hits the reflecting surface, it is irregularly reflected, and the irregularly reflected light is scattered on the document surface.

  According to a fifth aspect of the present invention, a lens that diverges light in the light source arrangement direction is disposed between the plurality of light sources and the document surface. According to this configuration, the illumination light emitted from the light source is diverged in the light source arrangement direction by the lens, and the diverged illumination light is overlapped in the adjacent illumination area on the document surface, so that the light amount distribution from the center to the periphery of this illumination area Becomes uniform.

  According to a sixth aspect of the present invention, the plurality of light sources are light emitting diodes.

  In the invention according to claim 7, the plurality of light sources emit white light.

  In the invention according to claim 8, the original is irradiated by irradiating illumination light from the illumination unit having the above structure onto the original surface, and the reflected light from the original surface is incident on the image sensor via a mirror. An image reading apparatus that reads an image.

  According to a ninth aspect of the present invention, there is provided an image forming apparatus equipped with the image reading apparatus having the above configuration.

  According to the first aspect of the present invention, the illumination light emitted from a plurality of light sources is restricted from being irradiated on the document surface with light having a angle exceeding a predetermined emission angle. Thus, variation in the color tone of the illumination light on the document surface in the light source arrangement direction can be suppressed.

  According to the second aspect of the invention, the original surface in the light source arrangement direction is continuously illuminated by the illumination light having the color differences ΔX and ΔY of 0.02 or less. The variation in the color tone of the illumination light can be suppressed.

  According to the third aspect of the present invention, it is possible to reliably restrict the light from the light source exceeding the predetermined emission angle from being irradiated on the document surface.

  According to the fourth aspect of the present invention, when light from a light source exceeding a predetermined emission angle hits a reflection surface between one end and the other end, the light is diffusely reflected, and the irregularly reflected light is converted into a document. Since the light is scattered on the surface, the illumination efficiency of the original surface can be increased without causing variations in the color tone of the illumination light.

  According to the fifth aspect of the present invention, the illumination light emitted from the light source is diverged in the light source arrangement direction by the lens, and the diverged illumination light is overlapped in the adjacent illumination areas on the document surface, whereby each illumination area The light quantity distribution is uniform from the center to the periphery, and the illuminance unevenness of the illumination light can be suppressed on the document surface in the light source arrangement direction.

  According to the invention described in claim 6, the illumination unit or the image reading apparatus can be reduced in size and the cost can be reduced.

  According to the seventh aspect of the invention, color unevenness of the illumination light can be suppressed on the document surface.

  According to the eighth aspect of the present invention, when the document surface is illuminated with illumination light emitted from the illumination unit, an image reading apparatus in which deterioration of read image quality is suppressed can be obtained.

  According to the ninth aspect of the present invention, when the original surface is illuminated with the illumination light emitted from the illumination unit, an image forming apparatus can be obtained in which deterioration of the read image quality is suppressed.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. The embodiment of the present invention shows the most preferable form of the invention, and the use of the invention and the terms shown here are not limited thereto.

(First embodiment)
FIG. 1 is a schematic sectional view showing an image forming apparatus according to an embodiment of the present invention. Note that solid arrows in the figure indicate the transport path and transport direction of the paper or document.

  As shown in FIG. 1, a cassette type paper feeding unit 20 is disposed at the lower part of the main body 2 of the image forming apparatus 1. The cassette type paper supply unit 20 includes a general general-purpose paper cassette 21 and a large capacity paper cassette 22. Two large-capacity paper cassettes 22 having the same capacity are arranged in the horizontal direction at the same height, a large-capacity paper cassette 22A is disposed on the upstream side, and a large-capacity paper cassette 22B is disposed on the downstream side. In these paper cassettes, paper P such as cut paper before printing is stacked and stored, and the paper P is separated and sent out one by one.

  A manual paper feed unit 3 is disposed on the upper right side of the cassette type paper feed unit 20. The manual paper feed unit 3 feeds sheets and OHP sheets that are not in the cassette type paper feed unit 20 one by one.

  A vertical conveyance path 4 is disposed on the right side of the cassette type paper feeding unit 20. The vertical conveyance path 4 conveys the paper P sent out from the cassette type paper feeding unit 20 vertically upward along the right side surface of the main body 2 and the paper P sent out from the manual paper feeding unit 3 horizontally leftward. . Of the two large-capacity paper cassettes 22, the paper P sent out from the large-capacity paper cassette 22A is fed right above the large-capacity paper cassette 22B horizontally and then along the right side of the main body 2. And is conveyed vertically upward.

  A registration roller 5 is disposed between the downstream end of the vertical conveyance path 4 in the sheet conveyance direction and the transfer unit 8. The registration roller 5 corrects the oblique feeding of the paper P and sends the paper P toward the transfer unit 8 in synchronization with the timing at which the image forming unit 7 forms a toner image.

  On the other hand, a document conveying unit 30 exposed to the outside is arranged on the upper surface of the main body 2 of the image forming apparatus 1, and a document reading unit 60 is arranged inside the main body 2 below the document conveying unit 30. The document conveying unit 30 and the document reading unit 60 constitute an image reading apparatus. In addition, an operation panel 6 on which the user confirms the display and performs button operations is arranged on the front surface of the main body 2.

  In response to an input instruction to start copying (copying), the document conveying unit 30 automatically conveys the documents placed on the document placing tray 31 one by one toward the document reading unit 60, When the original passing through the reading unit 60 is exposed and its image is read, the original is then discharged onto the original discharge tray 32, so-called sheet-through type original reading is performed. When the user performs copying for each original document, the original transport unit 30 is opened upward, the original document is placed on the original reading unit 60, and a print start operation is performed. The original 60 is exposed and scanned by the unit 60, and the image is read.

  The document reading unit 60 irradiates the document transported by the document transport unit 30 or the document placed on the contact glass, reads the document image from the reflected light, and converts the read image into an electrical signal. As a result, image data corresponding to the document image is generated. The document conveying unit 30 and the document reading unit 60 will be described in detail later.

  The image forming unit 7 forms an electrostatic latent image on the surface of the photosensitive drum by irradiating the photosensitive drum with laser light based on the image data of the original read by the original reading unit 60. The electrostatic latent image is developed with toner to form a toner image on the surface of the photosensitive drum. The transfer unit 8 transfers the toner image on the surface of the photosensitive drum to the paper P sent from the vertical conveyance path 4. Incidentally, when the electrostatic latent image on the surface of the photosensitive drum is successively developed with four toners of black, yellow, cyan and magenta and transferred onto the paper P, a color image is formed.

  The fixing unit 9 presses and heats the paper P onto which the toner image has been transferred by the transfer unit 8 between the heating roller and the pressure roller, thereby fixing the toner image on the paper P.

  A branching portion 10 is disposed in the vicinity of the left side surface of the main body 2 on the downstream side of the fixing portion 9. The branching unit 10 branches and conveys the paper discharged outside the apparatus and the paper for duplex printing. When performing double-sided printing, the paper P discharged from the fixing unit 9 is sent again from the branching unit 10 to the transfer unit 8 through the double-sided printing conveyance path 12 and the vertical conveyance path 4 in order, and the toner image is transferred to the sheet. Transfer to the back of P. When duplex printing is not performed, the fixed paper P is discharged from the branching unit 10 to the paper receiving tray 11 outside the apparatus.

  Next, a detailed configuration of the document conveying unit 30 of the image forming apparatus 1 will be described with reference to FIG. 2 in addition to FIG. FIG. 2 is a schematic cross-sectional view showing a main part of the document conveying unit 30. A solid arrow shown in FIG. 2 indicates the document conveyance direction.

  As shown in FIG. 1, the document transport unit 30 includes a document placement tray 31, a document supply unit 40, and a document discharge tray 32. The documents loaded on the document placement tray 31 are sent into the document supply unit 40, and after the image is read by the document reading unit 60, the document is discharged to the document discharge tray 32.

  The document supply unit 40 has a document insertion port 41 provided at the downstream end of the document loading tray 31 in the document conveyance direction, and extends substantially horizontally from the document insertion port 41, and has a U-shaped path toward the document discharge tray 32. A first document conveyance path 43 is provided.

  As shown in FIG. 2, on the first document conveyance path 43, a first conveyance roller pair 44, a second conveyance roller pair 48, and a first conveyance roller 43 that are in pressure contact with each other in the order in which the document is conveyed. A pair of three transport rollers 49 is provided. The document that has passed through the third conveyance roller pair 49 is sent to the document guide unit 50.

  The document guide 50 is provided immediately downstream of the third conveyance roller pair 49. While the document fed into the document guide unit 50 is moved further downstream on the first document transport path 43, the document image is formed by the first optical carriage 61 of the document reading unit 60 provided below the document guide unit 50. It is captured.

  A downstream side of the document guide unit 50 is provided with a fourth conveying roller pair 51 composed of rollers and rollers that come into pressure contact with each other, and further on the downstream side, a document discharge roller pair 56 is provided. The document that has passed through is discharged from the document discharge port 55 to the document discharge tray 32 by the document discharge roller pair 56.

  In the document supply unit 40, switching guides 46 and 53 are provided on the first document transport path 43 so as to be swingable so that the document transport direction is switched. When performing double-sided reading of a document, the document whose surface image has been read by the document guide unit 50 is guided to the second transport path 54 by the switching guide 53 and further guided to the third transport path 47 by the switching guide 46. When transported, the document is placed on the document tray 31 (see FIG. 1) with the back side up, so that the back side of the document can be read.

  FIG. 3 is a schematic cross-sectional view showing a document reading unit of the image reading apparatus. The document reading unit 60 includes contact glasses 63 and 64 for placing a document, and a scanner unit 70 that reads a document image and generates image data from the read document image. The contact glass 63 passes the original when reading a sheet-through type original, and the contact glass 64 is placed when the original is read by exposure scanning.

  The scanner unit 70 includes a first optical carriage 61 disposed below the contact glasses 63 and 64, a second optical carriage 72 disposed on the left side of the first optical carriage 61, and a lower part in the scanner unit 70. The image pickup unit 80 is disposed at an appropriate position.

  The first optical carriage 61 and the second optical carriage 72 are connected to a scanning mechanism section, and the scanning mechanism section moves at a predetermined speed in the arrow direction (left-right direction) shown in FIG. It is possible to scan the entire surface of the document placed on the scanner and read an image on the entire surface of the document.

  The first optical carriage 61 includes a frame body 75 connected to the scanning mechanism unit, a light source 76 such as a light emitting diode that irradiates light on a document placed on the contact glass 64, and light from the contact glass 64. 2 includes a mirror 78 that reflects toward the optical carriage 72.

  The second optical carriage 72 is provided with a pair of mirrors 72a and 72b disposed so as to face each other in the vertical direction, and the light from the mirror 78 of the first optical carriage 61 is sequentially reflected by the mirrors 72a and 72b. Guide to unit 80.

  The imaging unit 80 includes an imaging lens 73 and an image sensor 74 disposed on the right side of the imaging lens 73. The imaging lens 73 has a plurality of lenses for imaging the reflected light from the original that has entered via the mirror 72 b of the second optical carriage 72, and is fixed at a predetermined position of the imaging unit 80. The The image sensor 74 is an image sensor such as a CCD arranged on the optical axis Z of the optical system extending from the light source 76 to the imaging lens 73 in a direction perpendicular to the document transport direction (main scanning direction, depth direction in FIG. 3). The optical image of the original image formed on the image sensor by the imaging lens 73 is converted into an electrical signal.

  In the document reading unit 60 configured as described above, light is irradiated onto the contact glass 64 by the light source 76, and reflected light from the document on the contact glass 64 is reflected by the mirror 78 of the first optical carriage 61, and the reflected light is reflected. The light is sequentially reflected by the mirrors 72 a and 72 b of the second optical carriage 72, and an optical image of the document is formed on the image sensor 74 via the imaging lens 73. Thereby, a part of the document image is read. The scanning mechanism moves the first optical carriage 61 and the second optical carriage 72 at a predetermined speed, thereby scanning the entire surface of the document image and reading the entire surface of the document image to form a read image. .

  When reading a document image by the sheet-through type, the first and second optical carriages 61 and 72 shown in FIG. 3 move leftward in the scanner unit 70 and enter the mirror 78 of the first optical carriage 61. The optical axis Z is held at a position facing the contact glass 63. Then, in the document transport unit 30 (see FIG. 1), when the document is separated and transported one by one and passes over the contact glass 63, the document image is transferred to the first and second optical carriages 61 and 72 and the combined images. It is read by the image sensor 74 through the image lens 73.

  Next, an illumination unit including the light source will be described with reference to FIGS. FIG. 4 is a sectional plan view showing the first optical carriage, and FIG. 5 is a sectional view schematically showing a light source of the illumination unit.

  As shown in FIG. 4, the first optical carriage 61 includes a frame 75 formed in a plate shape, and an illumination unit 62 fixed and held toward the contact glass 64 in a bent portion extending above the frame 75. And a mirror 78 that is fixedly supported below the frame 75 and reflects reflected light from the document surface.

  The illumination unit 62 includes a circuit board 85 extending in a direction perpendicular to the moving direction of the first optical carriage 61 (main scanning direction, depth direction in FIG. 4), and a plurality of light sources mounted on the circuit board 85. 76. The illumination unit 62 is adjusted and fixed to the frame 75 so that the center of the light source 76 is positioned on the optical axis Z.

  Each light source 76 includes a light emitting diode, is arranged in a line in the main scanning direction at a predetermined interval, and has illumination that spreads around the optical axis Z toward the document surface 64a on which the document on the contact glass 64 is placed. Irradiate light. When the light emitting diodes emit light all at once, the plurality of light sources 76 illuminate the document surface 64a of the contact glass 64 in the main scanning direction.

  Each light source 76 emits white light. As shown in FIG. 5, a light emitting diode chip 76b that emits blue light is included in a resin package 76a, and a phosphor 76c having a yellow wavelength band covers the light emitting diode chip 76b. When a current is passed through the light emitting diode chip 76b, the light emitting diode chip 76b emits light, and when the blue light is transmitted through the phosphor 76c, the light in the red to green wavelength band obtained as fluorescence and the blue light are combined. White light including a wavelength in the visible light range of 400 nm to 700 nm is emitted from the light source 76.

  However, a uniform light emission color is not obtained depending on the light emission amount of the light emitting diode chip 76b, the angle emitted from the light emitting diode chip 76b, and the like.

  FIG. 6 is a diagram illustrating the spectral characteristics of white light emitted from the light source 76 in the present embodiment, where the X axis indicates the wavelength (unit: nm) and the Y axis indicates the spectral distribution (unit:%). 6 shows the spectral characteristics of light emitted at a half angle (unit: °) of the emission angle α with the optical axis Z of the light source 76 shown in FIG. 5 as the center, and the line shown at C in FIG. The spectral characteristic of the light radiate | emitted toward is shown. In the spectral characteristics shown in the figure, the peak of the spectral distribution near 450 nm on the short wavelength side is due to the blue light emitting diode chip 76 b, and the portion of the wavelength band of about 520 to 650 nm (green to red) on the right side is due to the phosphor 76 c. Light converted from blue. Here, in the wavelength range of approximately 520 to 650 nm (from green to red), the spectral distribution increases as the half angle of the emission angle α increases, and greatly deviates from those at other emission angles at −11.31 °, − Even at 9.93 °, it is deviated from other emission angles. This is because, as the emission angle increases, the distance passing through the phosphor 76c increases, so that the spectral distribution in the wavelength band from green to red increases in the spectral characteristics in the visible range, and yellowish white light is emitted. Light is emitted from the light source 76. As described above, the color tone of the white light varies depending on the emission angle from the light source 76.

  FIG. 7 shows the variation in the color tone of the white light on the chromaticity diagram. FIG. 7 is a diagram showing chromaticity coordinates in the XY coordinate system of the CIE (International Commission on Illumination), and according to the half angle (unit is °) of the emission angle α around the optical axis Z as in FIG. Chromaticity. As shown in FIG. 7, in the half angle of the irradiation angle α, the chromaticity coordinate X is in the chromaticity area from 0.28 to 0.288, and the chromaticity coordinate Y is from 0.267 to 0.288. The color difference ΔX in the degree area is approximately 0.008, and the color difference ΔY is approximately 0.021. When the color differences ΔX and ΔY are evaluated based on the color reproducibility of the read image with respect to the original image, if the color differences ΔX and ΔY are both within 0.02, the color tone varies as illumination light. Specifically, when a plurality of light sources 76 are arranged in a line in the main scanning direction and the original is illuminated by moving the light sources 76 in the sub-scanning direction, reading is performed due to variations in the color tone of the illumination light in the main scanning direction. In the image, striped white to gray shades are generated in the sub-scanning direction, and the quality of the read image is deteriorated. Therefore, when the original surface 64a is illuminated with illumination light having an emission angle α such that the color differences ΔX and ΔY are both 0.02 or less, it is possible to suppress deterioration in read image quality. From the chromaticity diagram of FIG. 7, the half angle of the emission angle α1 where the color differences ΔX and ΔY correspond to 0.02 or less is within approximately 9.9 °. Further, more preferable color differences ΔX and ΔY for suppressing variations in color tone are 0.01 or less, and the half angle of the emission angle α1 corresponding to the color differences ΔX and ΔY is approximately 8.5 ° or less.

  FIG. 8 shows a configuration of an illumination unit that satisfies the relationship of the emission angles. FIG. 8 is a cross-sectional side view in the main scanning direction showing an illumination unit provided with a plurality of light sources.

  As shown in FIG. 8, among the illumination lights emitted from the light source 76, the illumination light emitted at the emission angle α1 is a region in the main scanning direction centering on the optical axis Z on the document surface 64a of the contact glass 64. The luminous flux spreads at A. When the original image is illuminated so that the luminous flux in the region A is continuous in the main scanning direction, the original surface 64a in the main scanning direction is continuously illuminated by illumination light having color differences ΔX and ΔY of 0.02 or less. Variations in the color tone of light can be suppressed.

  A regulating member 88 is provided between the adjacent light sources 76 so that the region A is continuous in the main scanning direction. The restricting members 88 are disposed on both sides in the arrangement direction of the light sources 76 to restrict the light with an angle exceeding the emission angle α1 from being irradiated onto the document surface 64a. When the pair of regulating members 88 are provided in each light source 76, the illumination light having the emission angle α1 from each light source 76 continuously illuminates the document surface 64a in the main scanning direction.

  The regulating member 88 is formed of a plastic plate material, one end portion 88a is fixed to the circuit board 85, and the other end portion 88b intersects with the light having the emission angle α1 to regulate the light flux. The reflection surface 88c on the light source 76 side between the one end portion 88a and the other end portion 88b is formed with minute irregularities such as white and gray, and diffusely reflects when light exceeding the emission angle strikes. The light irregularly reflected by the reflecting surface 88c reaches the region A, and the illumination efficiency of the region A is increased. The light exceeding the emission angle illuminates the original surface 64a, but the light irregularly reflected by the reflecting surface 88c is scattered on the original surface 64a, so that the color tone of the illumination light does not vary. The reflective surface 88c may be subjected to a surface treatment such as white or gray coating, and the regulating member 88 may be a plastic material colored white or gray. In addition, the restricting member 88 is configured to restrict the light flux of each light source by a pair of plate members. However, the present invention is not limited to this, and a rectangular body integrated with the restricting member 88 for the adjacent light source 76 is provided between the light sources 76. It may be arranged. In this case as well, variation in the color tone of the illumination light can be suppressed as described above. Further, if the light flux is restricted so that the tip end portion 88b intersects the light having the emission angle α1 near the light source 76, the length to the tip end portion 88b of the regulating member 88 can be shortened.

  According to the illumination unit of the first embodiment, in the illumination unit 62 in which a plurality of light sources 76 that irradiate illumination light toward the document surface 64a are arranged in a line, between the adjacent light sources 76, the light source 76 and the document surface 64a. Since the restricting member 88 for restricting the emission angle α1 of the illumination light emitted toward the light source is restricted, the light source 76 is restricted from being irradiated with light having an angle exceeding the emission angle α1. Variations in the color tone of the illumination light on the document surface 64a in the arrangement direction are suppressed. In addition, variation in the color tone of the illumination light can be suppressed by a simple configuration in which the regulating member 88 is simply provided.

  Further, according to the illumination unit of the first embodiment, the regulating member 88 is arranged so that illumination light having color differences ΔX and ΔY of 0.02 or less illuminates the document surface 64a continuously in the direction of the light source 76. As a result, the original surface 64a in the light source 76 arrangement direction is continuously illuminated by the illumination light having the color differences ΔX and ΔY of 0.02 or less, so that the illumination light is irradiated on the original surface 64a in the light source 76 arrangement direction. Variation in color tone is suppressed.

  Further, according to the illumination unit of the first embodiment, the circuit board 85 on which the light source 76 is mounted is provided. The regulating member 88 has one end 88 a held by the circuit board 85 and the other end 88 b from the light source 76. By intersecting with the emission angle α1, it is possible to surely regulate the irradiation of the original surface 64a with light exceeding the predetermined emission angle α1.

  Further, according to the illumination unit of the first embodiment, the regulating member 88 includes the reflection surface 88c that reflects the light from the light source 76 between the one end portion 88a and the other end portion 88b, thereby exceeding the emission angle. When the light from the light source 76 hits the reflection surface 88c, it is irregularly reflected, and this irregularly reflected light is scattered on the original surface 64a. be able to.

  Further, according to the illumination unit of the first embodiment, by using light emitting diodes for the plurality of light sources 76, the illumination unit or the image reading device can be reduced in size and the cost can be reduced.

  Further, according to the image reading apparatus of the first embodiment, the original surface 64a is irradiated with illumination light from the illumination unit 62, and the original surface via the mirrors 78, 72a, 72b by exposure scanning or sheet through type. By causing the reflected light from 64a to enter the image sensor 74 and reading the original image, it is possible to suppress degradation of the read image quality.

(Second Embodiment)
FIG. 9 is a cross-sectional plan view showing the first optical carriage in the image reading apparatus according to the second embodiment of the present invention, and FIG. 10 is an illumination provided with a plurality of light sources according to the second embodiment of the present invention. It is a cross-sectional side view of the main scanning direction showing the unit. A description will be given of a configuration in which the illumination unit 62 includes a light guide lens, which is different from the first embodiment.

  As shown in FIG. 9, a light guide lens 86 is arranged on the optical axis Z with a predetermined distance between the light source 76 and the contact glass 64. The circuit board 85 on which the light source 76 is mounted and the light guide lens 86 are configured as a unit that is integrally held, and the unit is fixed to the frame body 75.

  On the sub-scanning surface (FIG. 9), the light guide lens 86 condenses illumination light emitted from the light source 76 toward the document surface 64a, for example, like a convex lens, and illuminates only a predetermined document image reading area. On the other hand, as shown in FIG. 10, the illumination light emitted from the light source 76 is diverged toward the document surface 64a on the main scanning surface like a concave lens, for example. Each light guide lens 86 is arranged to face each light source 76 and is formed in an array shape continuous in the main scanning direction.

  The regulating member 88 has one end 88a fixed to the circuit board 85 and the other end 88b intersecting with the light having the emission angle α1 of the light source 76 to regulate the light flux, and the other end 88b provided on the opposite side is also adjacent. The light flux is regulated by intersecting with the light having the emission angle α1 of the light source 76. The reflection surface 88c between the one end portion 88a and the other end portion 88b is formed with white or gray minute irregularities, and diffusely reflects when light exceeding the emission angle strikes. The light irregularly reflected by the reflecting surface 88c reaches the area A, and increases the illumination efficiency of the area A as in the first embodiment. On the upper surface of the regulating member 88, the light guide lens 86 is fixedly held at a predetermined distance from the light source 76 on the optical axis Z. The light guide lens 86 and the regulating member 88 may be configured as one block for each light source 76 and attached to the circuit board 85 so that each block corresponds to each light source 76. The light guide lens 86 may be formed of a flat lens such as a Fresnel lens, a gradient index lens, or a liquid crystal lens, and may be attached to the contact glass 64. If it is composed of a flat lens, the apparatus becomes compact.

  According to the illumination unit of the second embodiment, the light guide lens 86 that diverges the light in the light source 76 arrangement direction is disposed between the plurality of light sources 76 and the document surface 64a, so that the light is emitted at the emission angle α1. The illumination light is diverged by the light guide lens 86 in the light source 76 arrangement direction, and the illumination area A overlaps the adjacent illumination area A on the document surface 64a in the light source 76 arrangement direction. In general, the amount of light is reduced in the vicinity of the illumination area as compared with the center of the optical axis. However, as in the second embodiment, the illumination axis is overlapped with each other in the adjacent illumination area A, thereby the optical axis Z of the illumination area A. The light amount distribution is uniform from the center to the periphery, and unevenness in illuminance is suppressed on the original surface 64a in the direction of the light source 76. When the original surface 64a is illuminated with this illumination light, deterioration of the read image quality can be suppressed.

  The present invention can be used for an illumination unit in which a plurality of light sources are arranged in a line, an image reading apparatus including the illumination unit, and an image forming apparatus including the illumination unit.

1 is a cross-sectional plan view schematically showing an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a cross-sectional plan view showing a main part of a document conveying portion of the image reading apparatus in the image forming apparatus according to the first embodiment of the present invention. FIG. 2 is a cross-sectional plan view schematically showing a document reading unit of the image reading apparatus in the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional plan view showing a first optical carriage in the image reading apparatus according to the first embodiment of the present invention. These are sectional drawings which show typically the light source in the lighting unit concerning a 1st embodiment of the present invention. These are figures which show the spectral characteristics with respect to the output angle from the light source in the illumination unit which concerns on 1st Embodiment of this invention. These are figures which show chromaticity with respect to the emission angle from the light source in the illumination unit which concerns on 1st Embodiment of this invention. These are cross-sectional side views which show the structure of the illumination unit which concerns on 1st Embodiment of this invention. These are sectional top views which show the 1st optical carriage in the image reading apparatus which concerns on 2nd Embodiment of this invention. These are sectional side views which show the structure of the illumination unit which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 30 Original conveyance part 40 Original supply part 43 First conveyance path 50 Original guide part 60 Original reading part 61 First optical carriage 62 Illumination unit 63, 64 Contact glass 64a Original surface 70 Scanner part 72 Second optical carriage 73 Imaging lens 74 Image sensor 75 Frame 76 Light source 78 Mirror 80 Imaging unit 85 Circuit board 86 Light guide lens (lens)
88 restriction member 88a one end 88b other end 88c reflective surface

Claims (9)

In an illumination unit in which a plurality of light sources that irradiate illumination light toward the document surface are arranged in a line,
An illumination unit, wherein a regulating member that regulates an emission angle of illumination light emitted from the light source toward the document surface is disposed between the adjacent light sources.   When the color difference of the illumination light according to the emission angle in the chromaticity coordinate X of the XY coordinate system is represented by ΔX, and the color difference of the illumination light according to the emission angle in the chromaticity coordinate Y of the XY coordinate system is represented by ΔY, ΔX 2. The illumination unit according to claim 1, wherein the regulating member is disposed so that illumination light having ΔY of 0.02 or less continuously illuminates the document surface in the light source arrangement direction.   3. The illumination according to claim 1, further comprising: a substrate that holds the light source, wherein the one end portion of the regulating member is held by the substrate, and the other end portion intersects the emission angle. unit.   The lighting unit according to claim 3, wherein the restricting member includes a reflecting surface that reflects light from the light source between the one end and the other end.   The illumination unit according to claim 1, wherein a lens that diverges light in the light source arrangement direction is disposed between the plurality of light sources and the document surface.   The lighting unit according to claim 1, wherein the plurality of light sources are light emitting diodes.   The illumination unit according to claim 1, wherein the plurality of light sources emit white light.   The original image is formed by irradiating the original surface with illumination light from the illumination unit according to claim 1 and causing reflected light from the original surface to enter the image sensor via a mirror. An image reading apparatus for reading.   An image forming apparatus on which the image reading apparatus according to claim 8 is mounted.

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