US20010015892A1 - Image reading apparatus and light guide member used therefor - Google Patents
Image reading apparatus and light guide member used therefor Download PDFInfo
- Publication number
- US20010015892A1 US20010015892A1 US09/785,178 US78517801A US2001015892A1 US 20010015892 A1 US20010015892 A1 US 20010015892A1 US 78517801 A US78517801 A US 78517801A US 2001015892 A1 US2001015892 A1 US 2001015892A1
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- Prior art keywords
- light
- guide member
- light guide
- exit surface
- read line
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Images
Classifications
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/024—Details of scanning heads ; Means for illuminating the original
- H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
- H04N1/03—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array
- H04N1/031—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array the photodetectors having a one-to-one and optically positive correspondence with the scanned picture elements, e.g. linear contact sensors
- H04N1/0311—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array the photodetectors having a one-to-one and optically positive correspondence with the scanned picture elements, e.g. linear contact sensors using an array of elements to project the scanned image elements onto the photodetectors
- H04N1/0312—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array the photodetectors having a one-to-one and optically positive correspondence with the scanned picture elements, e.g. linear contact sensors using an array of elements to project the scanned image elements onto the photodetectors using an array of optical fibres or rod-lenses
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/024—Details of scanning heads ; Means for illuminating the original
- H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
- H04N1/03—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array
- H04N1/031—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array the photodetectors having a one-to-one and optically positive correspondence with the scanned picture elements, e.g. linear contact sensors
- H04N1/0314—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array the photodetectors having a one-to-one and optically positive correspondence with the scanned picture elements, e.g. linear contact sensors using photodetectors and illumination means mounted in the same plane on a common support or substrate
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/024—Details of scanning heads ; Means for illuminating the original
- H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
- H04N1/03—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array
- H04N1/031—Details of scanning heads ; Means for illuminating the original for picture information pick-up with photodetectors arranged in a substantially linear array the photodetectors having a one-to-one and optically positive correspondence with the scanned picture elements, e.g. linear contact sensors
- H04N1/0318—Integral pick-up heads, i.e. self-contained heads whose basic elements are a light-source, a lens array and a photodetector array which are supported by a single-piece frame
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- H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
- H04N2201/024—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted
- H04N2201/028—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up
- H04N2201/03—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted
- H04N2201/031—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted deleted
- H04N2201/03104—Integral pick-up heads, i.e. self-contained heads whose basic elements are a light source, a lens and a photodetector supported by a single-piece frame
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- H04N2201/024—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted
- H04N2201/028—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up
- H04N2201/03—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted
- H04N2201/031—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted deleted
- H04N2201/03104—Integral pick-up heads, i.e. self-contained heads whose basic elements are a light source, a lens and a photodetector supported by a single-piece frame
- H04N2201/03108—Components of integral heads
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- H04N2201/024—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted
- H04N2201/028—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up
- H04N2201/03—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted
- H04N2201/031—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted deleted
- H04N2201/03104—Integral pick-up heads, i.e. self-contained heads whose basic elements are a light source, a lens and a photodetector supported by a single-piece frame
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- H04N2201/024—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted
- H04N2201/028—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up
- H04N2201/03—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted
- H04N2201/031—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted deleted
- H04N2201/03104—Integral pick-up heads, i.e. self-contained heads whose basic elements are a light source, a lens and a photodetector supported by a single-piece frame
- H04N2201/03108—Components of integral heads
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- H04N2201/024—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted
- H04N2201/028—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up
- H04N2201/03—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted
- H04N2201/031—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted deleted
- H04N2201/03104—Integral pick-up heads, i.e. self-contained heads whose basic elements are a light source, a lens and a photodetector supported by a single-piece frame
- H04N2201/03108—Components of integral heads
- H04N2201/03145—Photodetector
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
- H04N2201/024—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted
- H04N2201/028—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up
- H04N2201/03—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted
- H04N2201/031—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof deleted for picture information pick-up deleted deleted
- H04N2201/03104—Integral pick-up heads, i.e. self-contained heads whose basic elements are a light source, a lens and a photodetector supported by a single-piece frame
- H04N2201/0315—Details of integral heads not otherwise provided for
- H04N2201/0317—Shape
Definitions
- the present invention relates to an image reading apparatus. It also relates to a light guide member used for an image reading apparatus.
- a typical image reading apparatus incorporating a linear image sensor is designed to illuminate an image read line of a document with light emitted from a light source.
- the light reflected at the image read line is received by a plurality of light receiving elements.
- Each of the light receiving elements outputs signals corresponding to the received amount of light.
- JP-A-9-307696 discloses an image reading apparatus in which a light guide member (prism) is arranged in facing relationship to a light source for guiding light emitted from the light source toward an image read line.
- a light guide member pris
- light from the light source can be directed toward the image read line even if the light source is not disposed in facing relationship to the image read line.
- the light guide member has a flat light incidence surface. Light entering the light guide member through the light incidence surface is emitted through a light exit surface toward the image read line.
- the light guide member with the flat light incidence surface has the following problems.
- the prior art image reading apparatus needs to be improved to enhance efficiency in illuminating the image read line.
- An object of the present invention to provide a light guide member which may be advantageously incorporated in such an image reading apparatus.
- an image reading apparatus comprises at least one light source, an elongate light guide member for guiding light emitted from the light source toward an image read line, and a plurality of light receiving elements for receiving light reflected at the image read line.
- the light guide member includes a first portion, a second portion, and a connecting portion for connecting the first portion and the second portion.
- the first portion includes a light incidence surface facing the light source for entry of light emitted from the light source, and the light incidence surface is convexly curved widthwise of the light guide member.
- the second portion includes a light exit surface oriented toward the image read line for emitting light toward the image read line.
- the connecting portion is narrower than the first portion and the second portion.
- the first portion of the light guide member further may include additional light exit surfaces each of which is convexly curved, whereas the second portion of the light guide member may further include an additional light incidence surface facing each light exit surface of the first portion.
- the first portion, the second portion and the connecting portion may be formed of transparent resin as one piece.
- the connecting portion may be located on a widthwise center axis of the first portion, and the widthwise center axis of the first portion may be located directly above the light source.
- the light exit surface of the second portion may be convexly curved at least partially.
- the light exit surface of the second portion may be offset widthwise toward the image read line relative to the light incidence surface of the first portion.
- an image reading apparatus which comprises at least one light source, an elongate light guide member for guiding light emitted from the light source toward an image read line, and a plurality of light receiving elements for receiving light reflected at the image read line.
- the light guide member includes a first portion, a second portion, and a connecting portion for connecting the first portion and the second portion.
- the first portion includes a first light incidence surface facing the light source for entry of light emitted from the light source, and at least one first light exit surface facing the second portion and convexly curved.
- the second portion includes at least one second light incidence surface facing the first light exit surface of the first portion for reentry of light, and a second light exit surface oriented toward the image read line for emitting light toward the image read line.
- the connecting portion is narrower than the first portion and the second portion.
- an elongate light guide member which comprises a first portion, a second portion, and a connecting portion connecting the first portion and the second portion.
- the first portion includes a light incidence surface oriented away from the second portion for entry of light and convexly curved widthwise of the light guide member.
- the second portion includes a light exit surface oriented away from the first portion for emitting light.
- the connecting portion is narrower than the first portion and the second portion.
- the first portion of the light guide member may further include additional light exit surfaces each of which is convexly curved, and the second portion of the light guide member may further include an additional light incidence surface facing each light exit surface of the first portion.
- the first portion, the second portion and the connecting portion may be formed of transparent resin as one piece.
- the connecting portion may be located on a widthwise center axis of the first portion.
- the light exit surface of the second portion may be convexly curved at least partially.
- the second portion includes a pair of side surfaces which are inclined with respect to a widthwise center axis of the first portion.
- an elongate light guide member which comprises a first portion, a second portion, and a connecting portion connecting the first portion and the second portion.
- the first portion includes a first light incidence surface oriented away from the second portion for entry of light, and at least one first light exit surface facing the second portion and convexly curved.
- the second portion includes at least one second light incidence surface facing the first light exit surface of the first portion for reentry of light, and a second light exit surface oriented away from the first portion for emitting light.
- the connecting portion is narrower than the first portion and the second portion.
- FIG. 1 is a sectional view showing an image reading apparatus embodying the present invention.
- FIG. 2 is a sectional view taken along lines II-II in FIG. 1.
- FIG. 3 a is a plan view of a light guide member incorporated in the image reading apparatus shown in FIG. 1.
- FIG. 3 b is a front view of the same light guide member.
- FIG. 3 c is a left side view of the same light guide member.
- FIG. 3 d is a sectional view taken along lines III-III in FIG. 3 b.
- FIGS. 1 and 2 illustrate an example of image reading apparatus in accordance with the present invention.
- FIG. 3 illustrates an example of light guide member in accordance with the present invention.
- the present invention is applied for a so-called flat bed type image reading apparatus for reading an image of a document disposed on a transparent document supporting panel.
- the illustrated image reading apparatus A is elongate in a primary scanning direction indicated by an arrow Na in FIG. 2.
- the image reading apparatus A generally comprises a plurality of light sources 2 , a light guide member 3 , a lens array 4 , a row of light receiving elements 5 , a substrate 6 , a housing 1 for accommodating these components, and a document supporting panel 7 .
- the housing 1 is made of a synthetic resin.
- the housing 1 is supported by a non-illustrated movable member below the document supporting panel 7 for movement in a secondary scanning direction indicated by an arrow Nb in FIG. 1.
- the substrate 6 is mounted at the bottom of the housing 1 .
- the lens array 4 comprises a row of image forming lenses 40 extending in the primary scanning direction, and a holder 41 made of a synthetic resin for holding the lenses 40 .
- Each of the lenses 40 may be a selfoc lens (self focusing lens) capable of forming an actual size erect image of a document D. Alternatively, use may be made of other lenses such as a convex lens.
- an image read line S extending in the primary scanning direction is defined in alignment with the row of lenses 40 .
- the row of light receiving elements 5 for photoelectric conversion is disposed directly below the lens array 4 on the substrate 6 in alignment with the lens array 4 .
- the light receiving element 5 outputs signals corresponding to the received amount of light.
- the light sources 2 are arranged on the substrate 6 at a predetermined pitch in a row extending in the primary scanning direction.
- Each of the light sources 2 may comprise an LED for example.
- the light guide member 3 may be formed by molding a transparent resin such as PMMA (polymethyl methacrylate (methacrylate resin)) or polycarbonate.
- the light guide member 3 which is elongate in the primary scanning direction, generally comprises a body 30 c having a uniform cross section, and a pair of engaging portions 30 a , 30 b provided at longitudinally opposite ends of the body 30 c . All surfaces of the light guide member 3 are mirror-finished. Therefore, when light traveling within the light guide member 3 impinges on the mirror surfaces of the light guide member 3 at an angle larger than the total reflection critical angle (which is determined depending on the material of the light guide member), it is totally reflected.
- PMMA polymethyl methacrylate (methacrylate resin)
- mirror surfaces of the light guide member 3 need not necessarily be polished to serve as mirror surfaces.
- mirror surfaces may be provided by resin-molding the light guide member 3 to have smooth surfaces.
- the body 30 c of the light guide member 3 comprises a first or lower portion 31 , a second or upper portion 32 and a connecting neck portion 33 .
- the lower portion 31 has a first light incidence surface 35 which is downwardly convex, and a pair of first light exit surfaces 37 a each of which is laterally and upwardly convex.
- the connecting neck portion 33 connects the lower portion 31 and the upper portion 32 .
- the provision of the connecting neck portion 33 allows the lower portion 31 and the upper portion 33 to be integrally formed.
- the light guide member 3 as a whole is formed as one piece.
- the connecting neck portion 33 is arranged so that a widthwise center of the connecting neck portion 33 coincides with a widthwise center axis C1 of the lower portion 31 .
- the connecting neck portion 33 has a smaller width s1 than the lower and the upper portions 31 , 32 .
- a pair of recesses 36 opposed widthwise of the light guide member 3 are formed between the lower portion 31 and the upper portion 32 .
- the upper portion 32 comprises a second light exit surface 38 , a pair of side surfaces 39 a , 39 b , and a pair of second light incidence surfaces 37 b .
- the second light incidence surfaces 37 b face the first light exit surfaces 37 a of the lower portion 31 , respectively.
- Each second light incidence surface 37 b is flat in this embodiment but may be convex.
- the side surface 39 a is inclined so that light entering the upper portion 32 from the lower portion 31 is totally reflected at the side surface 39 a toward the second light exit surface 38 .
- the second light exit surface 38 emits the light reflected by the side surface 39 a to the outside.
- the second light exit surface 38 is made entirely or generally entirely convex laterally upward.
- the light guide member 3 is arranged in the housing 1 with the widthwise center axis C1 of the lower portion 31 positioned directly above the light sources 2 so that the first light incidence surface 35 faces the light sources 2 .
- the second light exit surface 38 is oriented toward a reverse surface of the document supporting panel 7 .
- each of the engaging portions 30 a , 30 b is formed with a projection 34 a which fits into a non-illustrated recess of the housing 1 , thereby positioning the light guide member 3 relative to the housing 1 .
- the side surface 39 b of the upper portion 32 is formed with a plurality of projections 34 each of which fits into a corresponding recess 19 a formed in a partition member 19 of the housing 1 .
- the light guide member 3 is positively positioned relative to the housing 1 .
- the image reading apparatus A having the above-described structure operates as follows.
- the light entering the upper portion 32 reaches the side surface 39 a .
- the entire or almost entire portion of light is totally reflected by the side surface 39 a .
- a large amount of light can be directed toward the light exit surface 38 , and hence to the image read line S.
- the connecting neck portion may be a transitional portion indistinguishable from the lower portion and the upper portion.
- the lower and the upper portion may be connected directly.
- the portion at which the lower and the upper portions are connected may be regarded as a connecting neck portion.
- the present invention is applied to a flat bed type image reading apparatus.
- the present invention is applicable to other type of image reading apparatus such as a sheet feed type image reading apparatus in which image reading is performed with the document transferred in the secondary scanning direction by a platen roller, or an image reading apparatus for reading images on an electronic white board to make a copy of the image thereon.
- a cold cathode tube may be employed as a light source instead of LEDs.
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- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Facsimile Scanning Arrangements (AREA)
- Facsimile Heads (AREA)
- Light Guides In General And Applications Therefor (AREA)
- Lenses (AREA)
- Image Input (AREA)
Abstract
An image reading apparatus includes a light source, an elongate light guide member for guiding light emitted from the light source toward an image read line, and a plurality of light receiving elements for receiving light reflected at the image read line. The light guide member includes a first portion, a second portion, and a connecting portion for connecting the first portion and the second portion. The first portion includes a light incidence surface facing the light source for entry of light emitted from the light source, and the light incidence surface is convexly curved widthwise of the light guide member. The second portion includes a light exit surface oriented toward the image read line for emitting light toward the image read line. The connecting portion is narrower than the first portion and the second portion.
Description
- 1. Field of the Invention
- The present invention relates to an image reading apparatus. It also relates to a light guide member used for an image reading apparatus.
- 2. Description of the Related Art
- As is well known, a typical image reading apparatus incorporating a linear image sensor is designed to illuminate an image read line of a document with light emitted from a light source. The light reflected at the image read line is received by a plurality of light receiving elements. Each of the light receiving elements outputs signals corresponding to the received amount of light.
- With such an image reading apparatus, if the image read line is not illuminated sufficiently, the image reading quality may be deteriorated. Therefore, light emitted from the light source needs to be effectively directed to the image read line. For this purpose, JP-A-9-307696 for example discloses an image reading apparatus in which a light guide member (prism) is arranged in facing relationship to a light source for guiding light emitted from the light source toward an image read line. In this image reading apparatus, light from the light source can be directed toward the image read line even if the light source is not disposed in facing relationship to the image read line.
- In the above-described image reading apparatus, the light guide member has a flat light incidence surface. Light entering the light guide member through the light incidence surface is emitted through a light exit surface toward the image read line. However, the light guide member with the flat light incidence surface has the following problems.
- Generally, light emitted from the light source has a tendency to diverge as it travels. Since the light incidence surface of the prior art light guide member is flat, the light entering the light guide member through the light incidence surface continues to diverge within the light guide member. Therefore, the amount of light directed toward the light exit surface is reduced. Specifically, most of the light entering the light guide member travels toward the light exit surface while being totally reflected by the surfaces of the light guide member. However, since light disperses in various directions within the light guide member, a large amount of light impinges on the surfaces of the light guide member at an angle smaller than the total reflection critical angle, thereby passing through the light guide member. As a result, the amount of light guided toward the light exit surface is reduced, resulting in deterioration of the image reading quality.
- Moreover, even if a large amount of light is guided toward the light exit surface, it is difficult to efficiently illuminate the image read line because the light is not converged.
- Thus, the prior art image reading apparatus needs to be improved to enhance efficiency in illuminating the image read line.
- It is therefore an object of the present invention to provide an image reading apparatus which is capable of effectively illuminating an image read line of a document.
- An object of the present invention to provide a light guide member which may be advantageously incorporated in such an image reading apparatus.
- In accordance with a first aspect of the present invention, an image reading apparatus comprises at least one light source, an elongate light guide member for guiding light emitted from the light source toward an image read line, and a plurality of light receiving elements for receiving light reflected at the image read line. The light guide member includes a first portion, a second portion, and a connecting portion for connecting the first portion and the second portion. The first portion includes a light incidence surface facing the light source for entry of light emitted from the light source, and the light incidence surface is convexly curved widthwise of the light guide member. The second portion includes a light exit surface oriented toward the image read line for emitting light toward the image read line. The connecting portion is narrower than the first portion and the second portion.
- Preferably, the first portion of the light guide member further may include additional light exit surfaces each of which is convexly curved, whereas the second portion of the light guide member may further include an additional light incidence surface facing each light exit surface of the first portion.
- Preferably, the first portion, the second portion and the connecting portion may be formed of transparent resin as one piece.
- Preferably, the connecting portion may be located on a widthwise center axis of the first portion, and the widthwise center axis of the first portion may be located directly above the light source.
- Preferably, the light exit surface of the second portion may be convexly curved at least partially.
- Preferably, the light exit surface of the second portion may be offset widthwise toward the image read line relative to the light incidence surface of the first portion.
- According to a second aspect of the present invention, there is provided an image reading apparatus which comprises at least one light source, an elongate light guide member for guiding light emitted from the light source toward an image read line, and a plurality of light receiving elements for receiving light reflected at the image read line. The light guide member includes a first portion, a second portion, and a connecting portion for connecting the first portion and the second portion. The first portion includes a first light incidence surface facing the light source for entry of light emitted from the light source, and at least one first light exit surface facing the second portion and convexly curved. The second portion includes at least one second light incidence surface facing the first light exit surface of the first portion for reentry of light, and a second light exit surface oriented toward the image read line for emitting light toward the image read line. The connecting portion is narrower than the first portion and the second portion.
- According to a third aspect of the present invention, there is provided an elongate light guide member which comprises a first portion, a second portion, and a connecting portion connecting the first portion and the second portion. The first portion includes a light incidence surface oriented away from the second portion for entry of light and convexly curved widthwise of the light guide member. The second portion includes a light exit surface oriented away from the first portion for emitting light. The connecting portion is narrower than the first portion and the second portion.
- Preferably, the first portion of the light guide member may further include additional light exit surfaces each of which is convexly curved, and the second portion of the light guide member may further include an additional light incidence surface facing each light exit surface of the first portion.
- Preferably, the first portion, the second portion and the connecting portion may be formed of transparent resin as one piece.
- Preferably, the connecting portion may be located on a widthwise center axis of the first portion.
- Preferably, the light exit surface of the second portion may be convexly curved at least partially.
- Preferably, the second portion includes a pair of side surfaces which are inclined with respect to a widthwise center axis of the first portion.
- According to a fourth aspect of the present invention, there is provided an elongate light guide member which comprises a first portion, a second portion, and a connecting portion connecting the first portion and the second portion. The first portion includes a first light incidence surface oriented away from the second portion for entry of light, and at least one first light exit surface facing the second portion and convexly curved. The second portion includes at least one second light incidence surface facing the first light exit surface of the first portion for reentry of light, and a second light exit surface oriented away from the first portion for emitting light. The connecting portion is narrower than the first portion and the second portion.
- Other features and advantages of the present invention will become clearer from the detailed description given below with reference to the accompanying drawings.
- FIG. 1 is a sectional view showing an image reading apparatus embodying the present invention.
- FIG. 2 is a sectional view taken along lines II-II in FIG. 1.
- FIG. 3a is a plan view of a light guide member incorporated in the image reading apparatus shown in FIG. 1.
- FIG. 3b is a front view of the same light guide member.
- FIG. 3c is a left side view of the same light guide member.
- FIG. 3d is a sectional view taken along lines III-III in FIG. 3b.
- Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
- FIGS. 1 and 2 illustrate an example of image reading apparatus in accordance with the present invention. FIG. 3 illustrates an example of light guide member in accordance with the present invention. In this embodiment, the present invention is applied for a so-called flat bed type image reading apparatus for reading an image of a document disposed on a transparent document supporting panel.
- The illustrated image reading apparatus A is elongate in a primary scanning direction indicated by an arrow Na in FIG. 2. The image reading apparatus A generally comprises a plurality of
light sources 2, alight guide member 3, a lens array 4, a row of light receiving elements 5, a substrate 6, ahousing 1 for accommodating these components, and adocument supporting panel 7. - The
housing 1 is made of a synthetic resin. Thehousing 1 is supported by a non-illustrated movable member below thedocument supporting panel 7 for movement in a secondary scanning direction indicated by an arrow Nb in FIG. 1. The substrate 6 is mounted at the bottom of thehousing 1. - The lens array4 comprises a row of
image forming lenses 40 extending in the primary scanning direction, and aholder 41 made of a synthetic resin for holding thelenses 40. Each of thelenses 40 may be a selfoc lens (self focusing lens) capable of forming an actual size erect image of a document D. Alternatively, use may be made of other lenses such as a convex lens. On thedocument supporting panel 7, an image read line S extending in the primary scanning direction is defined in alignment with the row oflenses 40. - The row of light receiving elements5 for photoelectric conversion is disposed directly below the lens array 4 on the substrate 6 in alignment with the lens array 4. When each of the light receiving elements 5 receives light reflected on the image read line S and collected by the lens array 4, the light receiving element 5 outputs signals corresponding to the received amount of light.
- The
light sources 2 are arranged on the substrate 6 at a predetermined pitch in a row extending in the primary scanning direction. Each of thelight sources 2 may comprise an LED for example. - The
light guide member 3 may be formed by molding a transparent resin such as PMMA (polymethyl methacrylate (methacrylate resin)) or polycarbonate. Thelight guide member 3, which is elongate in the primary scanning direction, generally comprises abody 30 c having a uniform cross section, and a pair of engagingportions body 30 c. All surfaces of thelight guide member 3 are mirror-finished. Therefore, when light traveling within thelight guide member 3 impinges on the mirror surfaces of thelight guide member 3 at an angle larger than the total reflection critical angle (which is determined depending on the material of the light guide member), it is totally reflected. On the other hand, light impinging on the mirror surfaces of thelight guide member 3 at an angle smaller than the critical angle passes therethrough. The surfaces of thelight guide member 3 need not necessarily be polished to serve as mirror surfaces. In the present invention, mirror surfaces may be provided by resin-molding thelight guide member 3 to have smooth surfaces. - As clearly shown in FIGS. 1 and 3d, the
body 30 c of thelight guide member 3 comprises a first orlower portion 31, a second orupper portion 32 and a connectingneck portion 33. - The
lower portion 31 has a firstlight incidence surface 35 which is downwardly convex, and a pair of first light exit surfaces 37 a each of which is laterally and upwardly convex. - The connecting
neck portion 33 connects thelower portion 31 and theupper portion 32. The provision of the connectingneck portion 33 allows thelower portion 31 and theupper portion 33 to be integrally formed. In this embodiment, thelight guide member 3 as a whole is formed as one piece. The connectingneck portion 33 is arranged so that a widthwise center of the connectingneck portion 33 coincides with a widthwise center axis C1 of thelower portion 31. The connectingneck portion 33 has a smaller width s1 than the lower and theupper portions recesses 36 opposed widthwise of thelight guide member 3 are formed between thelower portion 31 and theupper portion 32. - The
upper portion 32 comprises a secondlight exit surface 38, a pair of side surfaces 39 a, 39 b, and a pair of second light incidence surfaces 37 b. The second light incidence surfaces 37 b face the first light exit surfaces 37 a of thelower portion 31, respectively. Each secondlight incidence surface 37 b is flat in this embodiment but may be convex. The side surface 39 a is inclined so that light entering theupper portion 32 from thelower portion 31 is totally reflected at theside surface 39 a toward the secondlight exit surface 38. The secondlight exit surface 38 emits the light reflected by theside surface 39 a to the outside. The secondlight exit surface 38 is made entirely or generally entirely convex laterally upward. - As clearly shown in FIG. 1, the
light guide member 3 is arranged in thehousing 1 with the widthwise center axis C1 of thelower portion 31 positioned directly above thelight sources 2 so that the firstlight incidence surface 35 faces thelight sources 2. The secondlight exit surface 38 is oriented toward a reverse surface of thedocument supporting panel 7. As clearly shown in FIG. 3, each of the engagingportions projection 34 a which fits into a non-illustrated recess of thehousing 1, thereby positioning thelight guide member 3 relative to thehousing 1. Further, theside surface 39 b of theupper portion 32 is formed with a plurality ofprojections 34 each of which fits into a corresponding recess 19 a formed in apartition member 19 of thehousing 1. As a result, thelight guide member 3 is positively positioned relative to thehousing 1. - The image reading apparatus A having the above-described structure operates as follows.
- Referring to FIG. 1, when the
light sources 2 are turned on, light emitted from thelight sources 2 enters thelower portion 31 through the firstlight incidence surface 35. At this time, since the firstlight incidence surface 35 is convexly curved, it works to refract the light substantially in the same way as a convex lens. As a result, the light diverging from thelight sources 2 converges widthwise in entering thelower portion 31. - After the light enters the
lower portion 31, a portion of light traveling at or near the widthwise center axis C1 of thelower portion 31 directly enters theupper portion 32 through the connectingneck portion 33. On the other hand, a portion of light traveling away from the widthwise center axis C1 exits thelower portion 31 through the first light exit surfaces 37 a, passing through therecesses 36 and the reentry surfaces 37 b before entering theupper portion 32. At this time, since each of the first light exit surfaces 37 a is convexly curved, the diverging portion of light impinging on the firstlight exit surface 37 a is again refracted inwardly widthwise. In this way, the widthwise light is twice refracted inwardly. As a result, the light emitted from thelight sources 2 can be reliably guided into theupper portion 2 generally along the widthwise center axis C1 of thelower portion 1. - The light entering the
upper portion 32 reaches theside surface 39 a. At this time, since the light travels in parallel or generally parallel with the center axis C1, the entire or almost entire portion of light is totally reflected by theside surface 39 a. Thus, a large amount of light can be directed toward thelight exit surface 38, and hence to the image read line S. As a result, it is possible to effectively illuminate the image read line S, thereby enhancing the image reading quality. - By contrast, light emitted from the
light sources 2 diverges longitudinally of thelight guide member 3. However, light is not converged in this direction so that the image read line S can be effectively illuminated over its entire length. - The specific structure of the image reading apparatus and the light guide member of the present invention is not limited to the embodiment described above but may be modified in various ways.
- For example, the connecting neck portion may be a transitional portion indistinguishable from the lower portion and the upper portion. In other words, the lower and the upper portion may be connected directly. In this case, the portion at which the lower and the upper portions are connected may be regarded as a connecting neck portion.
- In the embodiment described above, the present invention is applied to a flat bed type image reading apparatus. However, the present invention is applicable to other type of image reading apparatus such as a sheet feed type image reading apparatus in which image reading is performed with the document transferred in the secondary scanning direction by a platen roller, or an image reading apparatus for reading images on an electronic white board to make a copy of the image thereon.
- Further, a cold cathode tube may be employed as a light source instead of LEDs.
Claims (15)
1. An image reading apparatus comprising:
at least one light source;
an elongate light guide member for guiding light emitted from the light source toward an image read line; and
a plurality of light receiving elements for receiving light reflected at the image read line;
wherein the light guide member includes a first portion, a second portion, and a connecting portion for connecting the first portion and the second portion;
wherein the first portion includes a light incidence surface facing the light source for entry of light emitted from the light source, the light incidence surface being convexly curved widthwise of the light guide member;
wherein the second portion includes a light exit surface oriented toward the image read line for emitting light toward the image read line; and
wherein the connecting portion is narrower than the first portion and the second portion.
2. The image reading apparatus according to , wherein the first portion of the light guide member further includes additional light exit surfaces each of which is convexly curved, the second portion of the light guide member further including an additional light incidence surface facing each light exit surface of the first portion.
claim 1
3. The image reading apparatus according to , wherein the first portion, the second portion and the connecting portion are formed of transparent resin as one piece.
claim 1
4. The image reading apparatus according to , wherein the connecting portion is located on a widthwise center axis of the first portion.
claim 1
5. The image reading apparatus according to , wherein the widthwise center axis of the first portion is located directly above the light source.
claim 4
6. The image reading apparatus according to , wherein the light exit surface of the second portion is convexly curved at least partially.
claim 1
7. The image reading apparatus according to , wherein the light exit surface of the second portion is offset widthwise toward the image read line relative to the light incidence surface of the first portion.
claim 1
8. An image reading apparatus comprising:
at least one light source;
an elongate light guide member for guiding light emitted from the light source toward an image read line; and
a plurality of light receiving elements for receiving light reflected at the image read line;
wherein the light guide member includes a first portion, a second portion, and a connecting portion for connecting the first portion and the second portion;
wherein the first portion includes a first light incidence surface facing the light source for entry of light emitted from the light source, and at least one first light exit surface facing the second portion, the first light exit surface being convexly curved;
wherein the second portion includes at least one second light incidence surface facing the first light exit surface of the first portion for reentry of light, and a second light exit surface oriented toward the image read line for emitting light toward the image read line; and
wherein the connecting portion is narrower than the first portion and the second portion.
9. An elongate light guide member comprising:
a first portion;
a second portion; and
a connecting portion connecting the first portion and the second portion;
wherein the first portion includes a light incidence surface oriented away from the second portion for entry of light, the light incidence surface being convexly curved widthwise of the light guide member;
wherein the second portion includes a light exit surface oriented away from the first portion for emitting light; and
wherein the connecting portion is narrower than the first portion and the second portion.
10. The light guide member according to , wherein the first portion of the light guide member further includes additional light exit surfaces each of which is convexly curved, the second portion of the light guide member further including an additional light incidence surface facing each light exit surface of the first portion.
claim 9
11. The light guide member according to , wherein the first portion, the second portion and the connecting portion are formed of transparent resin as one piece.
claim 9
12. The light guide member according to , wherein the connecting portion is located on a widthwise center axis of the first portion.
claim 9
13. The light guide member according to , wherein the light exit surface of the second portion is convexly curved at least partially.
claim 9
14. The light guide member according to , wherein the second portion includes a pair of side surfaces which are inclined with respect to a widthwise center axis of the first portion.
claim 9
15. An elongate light guide member comprising:
a first portion;
a second portion; and
a connecting portion connecting the first portion and the second portion;
wherein the first portion includes a first light incidence surface oriented away from the second portion for entry of light, and at least one first light exit surface facing the second portion, the first light exit surface being convexly curved;
wherein the second portion includes at least one second light incidence surface facing the first light exit surface of the first portion for reentry of light, and a second light exit surface oriented away from the first portion for emitting light; and
wherein the connecting portion is narrower than the first portion and the second portion.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000046012A JP2001238048A (en) | 2000-02-23 | 2000-02-23 | Image reader and light guiding member used for the same |
JP2000-046012 | 2000-02-23 |
Publications (2)
Publication Number | Publication Date |
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US20010015892A1 true US20010015892A1 (en) | 2001-08-23 |
US6455834B2 US6455834B2 (en) | 2002-09-24 |
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Application Number | Title | Priority Date | Filing Date |
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US09/785,178 Expired - Fee Related US6455834B2 (en) | 2000-02-23 | 2001-02-20 | Image reading apparatus and light guide member used therefor |
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US (1) | US6455834B2 (en) |
JP (1) | JP2001238048A (en) |
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US20100129116A1 (en) * | 2008-11-25 | 2010-05-27 | Ricoh Company, Ltd. | Light projecting device, image reading device including same, and image forming apparatus including the image reading device |
US20130221205A1 (en) * | 2012-02-29 | 2013-08-29 | Fuji Xerox Co., Ltd. | Light amount detector and image forming apparatus |
US8870435B2 (en) | 2012-07-03 | 2014-10-28 | Konica Minolta, Inc. | Light guide |
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US11330134B2 (en) | 2017-04-12 | 2022-05-10 | Mitsubishi Electric Corporation | Image reading device having a rectangular-shaped opening on a side of a reading target, wherein long sides of the rectangular shaped opening including a first layer, a second layer and an interface between the first layer and the second layer that has an arched shape warping from a center portion of the rectangular-shaped opening |
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WO1997023991A1 (en) * | 1995-12-26 | 1997-07-03 | Rohm Co., Ltd. | Contact-type image sensor |
JP3727718B2 (en) | 1996-05-10 | 2005-12-14 | ローム株式会社 | Contact image sensor |
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US6195183B1 (en) * | 1997-07-15 | 2001-02-27 | Rohm Co., Ltd. | Image reading apparatus and image sensor chip thererfor |
US6259082B1 (en) * | 1997-07-31 | 2001-07-10 | Rohm Co., Ltd. | Image reading apparatus |
-
2000
- 2000-02-23 JP JP2000046012A patent/JP2001238048A/en active Pending
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US20100129116A1 (en) * | 2008-11-25 | 2010-05-27 | Ricoh Company, Ltd. | Light projecting device, image reading device including same, and image forming apparatus including the image reading device |
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US8798500B2 (en) | 2008-11-25 | 2014-08-05 | Ricoh Company, Ltd. | Light projecting device, image reading device including same, and image forming apparatus including the image reading device |
US20130221205A1 (en) * | 2012-02-29 | 2013-08-29 | Fuji Xerox Co., Ltd. | Light amount detector and image forming apparatus |
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US11330134B2 (en) | 2017-04-12 | 2022-05-10 | Mitsubishi Electric Corporation | Image reading device having a rectangular-shaped opening on a side of a reading target, wherein long sides of the rectangular shaped opening including a first layer, a second layer and an interface between the first layer and the second layer that has an arched shape warping from a center portion of the rectangular-shaped opening |
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Also Published As
Publication number | Publication date |
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JP2001238048A (en) | 2001-08-31 |
US6455834B2 (en) | 2002-09-24 |
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