Abstract: Provided is an image reading apparatus that can read an image with highly accurate and stable density and color while illuminating the image with a color sequential projector thereof. The image reading apparatus according to the present invention includes: an image pickup unit configured to image an original that is mounted on a mounting surface; a projecting unit configured to project an image on the mounting surface by sequentially switching and emitting light of a plurality of colors; and a control unit configured to control the projecting unit so as to project a first black image, a first color image, and a second black image in this order during the imaging by the image pickup unit.

Abstract: An image reading method in the present invention includes: obtaining a pickup image by performing image pickup of an object mounted on a mounting surface with an imaging unit; and extracting an image of the object from the pickup image, based on a brightness difference between the image of the object and an image of a shadow of the object in the pickup image.

Abstract: An image reading device includes a platen on which an original is to be placed, an illuminating unit configured to illuminate the original, a linear sensor configured to receive light from the original, an optical unit configured to guide the light from the original to the linear sensor, and an aligning portion configured to determine a position of the original in a long-side direction of the linear sensor. The illuminating unit includes a light-guiding member extending in the long-side direction of the linear sensor, and a light source provided only at one long-side end of the light-guiding member. The aligning portion is provided on a side opposite to the light source in the long-side direction of the light-guiding member.

Abstract: An illumination device and an image reading apparatus having improved heat resistance and spectral characteristics are provided. An illumination device used in an image reading apparatus that moves relative to a read area of a document includes: a light source; a light guide including an incident surface on which light from the light source is incident and an exit surface from which light from the light source exits; and a spectroscopic unit that is provided between the light source and the light guide and includes, on a surface of a glass substrate facing the light source, a multi-layer film for reflecting infrared light toward the light source.

Abstract: The image reading apparatus includes a light transmissive member, a first light source causing a first light to enter the light transmissive member from a first side face of side faces thereof, a second light source illuminating a document laid on an upper face of the light transmissive member with a second light, an image sensor photoelectrically converting an optical image, and an imaging optical system forming on image sensor the object image with light exiting from the light transmissive member. The first light source is disposed such that the first light emitted therefrom and entering the light transmissive member from the first side face satisfies a total reflection condition at the upper and lower faces of the light transmissive member.

Abstract: An image reading device includes a platen on which an original is to be placed, an illuminating unit configured to illuminate the original, a linear sensor configured to receive light from the original, an optical unit configured to guide the light from the original to the linear sensor, and an aligning portion configured to determine a position of the original in a long-side direction of the linear sensor. The illuminating unit includes a light-guiding member extending in the long-side direction of the linear sensor, and a light source provided only at one long-side end of the light-guiding member. The aligning portion is provided on a side opposite the light source in the long-side direction of the light-guiding member.

Abstract: A method detects the floating amount of an original from an original table based on image information read by an image reading apparatus having the original table on which the original is placed, a line sensor, and a lens array arranged in a direction of arrangement of pixels of the line sensor. The method includes obtaining image information of the original as line image information by performing scanning in the direction of arrangement of pixels of the line sensor, extracting a distinguishing portion from the line image information, detecting a characteristic frequency by frequency analysis of image information of the distinguishing portion, and determining the floating amount of the original from the characteristic frequency.

Abstract: An illumination device and an image reading apparatus having improved heat resistance and spectral characteristics are provided. An illumination device used in an image reading apparatus that moves relative to a read area of a document includes: a light source; a light guide including an incident surface on which light from the light source is incident and an exit surface from which light from the light source exits; and a spectroscopic unit that is provided between the light source and the light guide and includes, on a surface of a glass substrate facing the light source, a multi-layer film for reflecting infrared light toward the light source.

Abstract: An inspection method for an image reading apparatus where image information of an original is imaged on light receiving element lines arranged in a main scanning direction to read the information on different colors. The method includes: acquiring a first color misregistration from image information based on a first striped pattern located at a position optically equivalent to a surface of the original with respect to the light receiving element lines, the first pattern having white and black lines aligned, and having longitudinal directions of the white and black lines aligned in a sub-scanning direction; acquiring a second color misregistration from image information based on a second striped pattern having white and black lines aligned, and having longitudinal directions of the white and black lines aligned at an angle from the main scanning direction; and calculating a color misregistration in the sub-scanning direction based on the measured color misregistrations.

Abstract: The image reading apparatus includes a light transmissive member, a first light source causing a first light to enter the light transmissive member from a first side face of side faces thereof, a second light source illuminating a document laid on an upper face of the light transmissive member with a second light, an image sensor photoelectrically converting an optical image, and an imaging optical system forming on image sensor the object image with light exiting from the light transmissive member. The first light source is disposed such that the first light emitted therefrom and entering the light transmissive member from the first side face satisfies a total reflection condition at the upper and lower faces of the light transmissive member.

Abstract: An adjusting method for a lens unit used in an image reading apparatus which images image information of an original onto an image reading unit by the lens unit and reads the image information, the lens unit including rotationally-symmetrical lenses, a lens barrel including the rotationally-symmetrical lenses and an adjusting lens, the adjusting method including: performing rotational adjustment of the lens barrel with respect to the adjusting lens; and imaging an adjusted chart onto one-dimensional photoelectric transducers via the lens unit, obtaining contrast depth characteristics of images corresponding to at least three angles of field of the lens unit among images of the adjusted chart, and, according to the obtained contrast depth characteristics, performing position adjustment of the adjusting lens in at least one of an array direction of the one-dimensional photoelectric transducers, a direction orthogonal to the array direction and an optical axis direction of the lens unit.

Abstract: An adjusting method for a lens unit used in an image reading apparatus which images image information of an original onto an image reading unit by the lens unit and reads the image information, the lens unit including rotationally-symmetrical lenses, a lens barrel including the rotationally-symmetrical lenses and an adjusting lens, the adjusting method including: performing rotational adjustment of the lens barrel with respect to the adjusting lens; and imaging an adjusted chart onto one-dimensional photoelectric transducers via the lens unit, obtaining contrast depth characteristics of images corresponding to at least three angles of field of the lens unit among images of the adjusted chart, and, according to the obtained contrast depth characteristics, performing position adjustment of the adjusting lens in at least one of an array direction of the one-dimensional photoelectric transducers, a direction orthogonal to the array direction and an optical axis direction of the lens unit.

Abstract: An inspection method for an image reading apparatus where image information of an original is imaged on light receiving element lines arranged in a main scanning direction to read the information on different colors. The method includes: acquiring a first color misregistration from image information based on a first striped pattern located at a position optically equivalent to a surface of the original with respect to the light receiving element lines, the first pattern having white and black lines aligned, and having longitudinal directions of the white and black lines aligned in a sub-scanning direction; acquiring a second color misregistration from image information based on a second striped pattern having white and black lines aligned, and having longitudinal directions of the white and black lines aligned at an angle from the main scanning direction; and calculating a color misregistration in the sub-scanning direction based on the measured color misregistrations.

Abstract: An object is to provide an imaging optical system having a very simple structure that can read image while maintaining excellent image quality without suffering from significant asymmetrical aberrations. An imaging optical system for image reading is adapted to form an image of image information on a surface of an original onto a line sensor while changing a relative position of the original surface and the line sensor to allow the line sensor to read the image information. The imaging optical system includes two off-axial reflecting surfaces, and the two off-axial surfaces are a plus deflecting surface and a minus deflecting surface, or a minus deflecting surface and a plus deflecting surface disposed in the mentioned order from the original surface side, where an off-axial reflecting surface that deflects a reference axis beam clockwise is defined as a minus deflecting surfaces and an off axial reflecting surface that deflects the reference axis beam anticlockwise is defined as a plus deflecting surface.

Abstract: A light guide optical system guides a plurality of light beams emitted from a plurality of point light sources arranged linearly to a predetermined surface. The light guide optical system has a plurality of optical surfaces arranged periodically in the arrangement direction of the plurality of point light sources. Each of the plurality of optical surfaces has power in the arrangement direction of the plurality of point light sources.

Abstract: An image reading apparatus includes a visible light source; an infrared light source; at least three one-dimensional photoelectric conversion elements extending in a main scanning direction and having respective different spectral sensitivity characteristics; an imaging optical system configured to form an image of image information of an original placed on an original holder and irradiated by the visible light source and the infrared light source on the one-dimensional photoelectric conversion elements; a driving unit configured to change relative optical positions of the imaging optical system and the original in a sub-scanning direction; and a control unit configured to obtain visible-light image information and infrared-light image information of the original by controlling turning-on operations of the visible light source and the infrared light source at every reading in the main scanning direction and by performing relative movement of the image optical system and the original in the sub-scanning direct

Abstract: An object is to provide an imaging optical system having a very simple structure that can read image while maintaining excellent image quality without suffering from significant asymmetrical aberrations. An imaging optical system for image reading is adapted to form an image of image information on a surface of an original onto a line sensor while changing a relative position of the original surface and the line sensor to allow the line sensor to read the image information. The imaging optical system includes two off-axial reflecting surfaces, and the two off-axial surfaces are a plus deflecting surface and a minus deflecting surface, or a minus deflecting surface and a plus deflecting surface disposed in the mentioned order from the original surface side, where an off-axial reflecting surface that deflects a reference axis beam clockwise is defined as a minus deflecting surfaces and an off axial reflecting surface that deflects the reference axis beam anticlockwise is defined as a plus deflecting surface.

Abstract: An image reading apparatus including a light source for illuminating an original, a plurality of mirrors for reflecting a light beam from the original illuminated by the light source, a reading device, an imaging optical system for imaging a light beam reflected by the mirrors, upon the reading device, and a scanning optical system unit which integrally accommodates theses components therein and moves in a sub-scan direction to read imagewise information of the original, wherein, in a sub-scan section, one mirror optically closest to the surface of the original is disposed in an end portion of the scanning optical system unit in the sub-scan direction, as compared with the other mirrors, and wherein the central portion of the reflection surface of one mirror optically closest to the original is disposed in a space between the central portion of the reflection surface of a mirror optically closest to the light entrance surface of the imaging optical system and central portions reflection surfaces of other mirr

Abstract: A lens unit and an image reading apparatus configured to hold an anamorphic lens precisely with a simple structure, without a lens spacing error or eccentric error: the lens unit including a barrel member configured to hold at least one rotationally symmetric lens having a rotationally symmetric shape with respect to an optical axis; an anamorphic lens having at least one anamorphic surface circumscribing an end portion of the barrel member; a coaxiality maintaining device configured to engage the anamorphic lens and the barrel member with each other to align central axes of the anamorphic lens and the barrel member with each other, and arranged relatively rotate the anamorphic lens and the barrel member relative to each other with reference to the aligned central axes of them; and an elastic member configured to push the anamorphic lens against the barrel member.

Abstract: An object is to provide an imaging optical system having a very simple structure that can read image while maintaining excellent image quality without suffering from significant asymmetrical aberrations. An imaging optical system for image reading is adapted to form an image of image information on a surface of an original onto a line sensor while changing a relative position of the original surface and the line sensor to allow the line sensor to read the image information. The imaging optical system includes two off-axial reflecting surfaces, and the two off-axial surfaces are a plus deflecting surface and a minus deflecting surface, or a minus deflecting surface and a plus deflecting surface disposed in the mentioned order from the original surface side, where an off-axial reflecting surface that deflects a reference axis beam clockwise is defined as a minus deflecting surfaces and an off-axial reflecting surface that deflects the reference axis beam anticlockwise is defined as a plus deflecting surface.