JP2007243353A - Optical detection mechanism and image reader provided therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical detection mechanism for suppressing effects of external light without increasing the number of components, and also, improving a design flexibility of an original-platen, and an image reader provided with the same. <P>SOLUTION: In the optical detection mechanism, an optical detector 112 is provided with a light emitter 112a for supporting a light-emitting element, and a light receiver 112b for supporting a light-receiving element. The light-emitting element and the light-receiving element are arranged opposite to each other for support. The light emitter 112a and light receiver 112b are formed so as to be protruded toward a light shield part 111a of a guide bar 111 with a prescribed space between them. An eaves-like external-light shield part 111d is integrally formed to the upper end of the light shield part 111a. The external-light shield part 111d shields incidence of the external-light into the light-receiving element when the light shield part 111a is moved between the light emitter 112a and the light receiver 112b when moving for plug in/off. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus which can be applied to an image forming apparatus such as a copying machine or a facsimile apparatus and which can read an original, and a light detection mechanism which can be applied to the image reading apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus equipped with an automatic document feeder (ADF), a sheet fixing type in which an original is conveyed by a conveying belt and positioned on a platen glass, and a scanner moves under the platen glass to read the original. A sheet-through type is known in which a scanner is stopped below a platen glass and the original is read while being conveyed on the platen glass at a constant speed.

In the sheet-through type, a document to be read can be set on a document placing table such as a hopper and automatically conveyed one by one to read the document. Such a document placing table is provided with a detection mechanism for detecting the size of the document. As the detection mechanism, for example, a light detection unit using a light emitting element and a light receiving element is used. However, it is necessary to prevent external light other than the light emitting element from entering the light receiving element and causing erroneous detection. For example, in Patent Document 1, in a document separating and conveying apparatus that separates documents one by one from a plurality of documents set in a document setting unit and conveys them to a document reading unit or a document stack unit, A reflective photosensor that detects the size of the standard paper is provided facing the paper set surface upward, and disturbs the ambient light from above the photosensor to the extent that the photosensor does not falsely detect it. The point that the light shielding means is detachably attached to the apparatus main body is described. Further, in Patent Document 2, a document reading apparatus configured to guide scanning light on a document surface to an image sensor attached to a sensor support member through a lens unit provided in an optical housing and an opening provided in the sensor support member. An image sensor light blocking structure for preventing disturbance light from entering the image sensor in the optical system is described. Further, in Patent Document 3, a base material having a light-transmitting portion that partially transmits light from a light source, and a layer that is provided on a surface of the base material that faces a reading surface of a document and shields ambient light are formed. There is described an image reading apparatus having a sensor substrate that includes an electric circuit layer that is formed and a light receiving sensor that is mounted on the electric circuit layer and receives an image formed by a lens.
JP-A-10-293366 Japanese Utility Model Publication No. 5-31446 Japanese Patent Laid-Open No. 9-284475

  In the above-described prior art, external light is shielded to prevent false detection and noise of the photosensor due to external light. For this reason, the photosensor is installed in an interior where the influence of external light is as small as possible. Need to be isolated from outside light.

  The document table mounted on the image reading device is arranged on the upper part of the device that is most susceptible to the influence of external light. Therefore, the light detection mechanism that detects the size of the document mounted on the document table is influenced by the external light. It is necessary to take measures to avoid as much as possible. However, if such measures are taken, the number of parts for that purpose will increase, and the degree of freedom in designing the document placement table will be limited.

  Therefore, the present invention provides a light detection mechanism capable of suppressing the influence of external light without increasing the number of parts and increasing the degree of freedom in design design of the document placement table, and an image reading apparatus including the same. It is intended to provide.

  The light detection mechanism according to the present invention includes a support member in which a pair of light emitting elements and a light receiving element are arranged so as to face each other, and a light shielding member that moves between the light emitting element and the light receiving element, and the light shielding member Is characterized in that an external light shielding portion covering the light receiving element is integrally formed. Further, the outside light shielding portion is formed in an eaves shape at an end portion of the light shielding member.

  An image reading apparatus according to the present invention is an image reading apparatus that includes a document placement table and a main body that rotatably holds the document placement table, and a pair of light emitting elements is provided on a bottom surface of the document placement table. And a support member arranged so that the light receiving elements are opposed to each other, and a light shielding member that moves in and out between the light emitting element and the light receiving element in conjunction with a document guide, An external light shielding portion that covers the light receiving element is integrally formed. Further, the outside light shielding portion is formed in an eaves shape along the bottom surface of the document table at the lower end of the light shielding member.

  Since the light detection mechanism according to the present invention has the above-described configuration, the external light shielding portion is integrally formed on the light shielding member that is inserted and removed between the light emitting element and the light receiving element. There is no need for parts and there is no burden of installation work. In addition, by providing the light shielding member with the function of shielding external light, the light detection mechanism can be arranged even in a place that is easily affected by external light, and the light detection mechanism can be made compact. It becomes possible to increase the degree of freedom of design.

  If the external light shielding portion is formed in an eaves shape at the end of the light shielding member, the external light can be reliably shielded with a simple configuration.

  Further, the image reading apparatus according to the present invention has the above-described configuration, so that a supporting member having a pair of light emitting elements and light receiving elements arranged on the bottom surface of the document placing table so as to face each other, and a document guide When a light shielding member that moves in and out between the light emitting element and the light receiving element in conjunction with each other is provided, an external light shielding portion that covers the light receiving element can be integrally formed on the light shielding member to reliably shield external light. In particular, the document table is placed in the upper part of the apparatus and is in an environment that is susceptible to the influence of external light, such as rotating. However, by forming an external light shielding part on the light shielding member, erroneous detection can be prevented, and separate parts Therefore, the design of the document table is not limited.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  FIG. 1 is a schematic sectional view of an entire image forming apparatus to which an image reading apparatus according to the present invention can be applied. An image reading apparatus A having a document conveying section 1 and a document reading section 2 for reading a document is arranged in the upper part of the image forming apparatus, a recording section 3 for recording an image in the lower section, and a sheet for conveying a sheet for recording an image. A transport unit 4 and two paper feed units 5 and 6 are arranged.

  In the document transport unit 1, a document is carried in by a document tray 10, a pickup roller 11, a separation roller 12, and a retard roller 13 that are document placement tables. In other words, the document placed on the document tray 10 is drawn by the pickup roller 11, and the leading end of the document is sandwiched between the separation roller 12 and the retard roller 13. The separation roller 12 rotates clockwise to pull in the document, but the retard roller 13 also rotates clockwise to prevent the document from being pulled in. Therefore, the double feeding of the document is prevented and the document is It is carried in one by one. Next, the document is nipped and conveyed by the feed roller 14 and the press roller 15, and the leading end of the document reaches between the feed roller 16 and the press roller 17 along the guide. Here, when the leading edge of the document is detected by the document detection sensor, the feed roller 16 starts transporting, the leading edge of the document is sandwiched between the feed roller 18 and the press roller 19, and the document is transported at a constant speed. . Meanwhile, the document is read by the document reading unit 2 on the platen 23. The document thus conveyed and read is conveyed between the discharge roller 20 and the press roller 21 and is carried out to the document discharge tray 22.

  In the document reading unit 2, light is irradiated toward the platen 23 by the lamp 24, and reflected light from the document is guided to the CCD 25 by a mirror and converted into an electrical signal.

  In the recording unit 3, a toner container 26, a charging brush 29, a photosensitive drum 30, a transfer roller 31, an exposure head 32, and a fixing roller 33 are provided for recording on the sheet conveyed by the sheet conveying unit 4. First, the surface of the photosensitive drum 30 is uniformly charged by the charging brush 29, and an electrostatic latent image is formed by exposing the charged photosensitive drum 30 according to an image recording signal by the exposure head 32. Next, the toner in the toner container 26 is transferred from the supply roller 27 to the electrostatic latent image formed on the photosensitive drum 30 via the developing roller 28 to be visualized, and the surface of the photosensitive drum 30 is transferred by the transfer roller 31. The toner image formed on the sheet is transferred to a sheet. The transferred toner image is sandwiched between the fixing roller 33 and the press roller 34 and heated and pressed to be fixed on the paper.

  In the paper transport unit 4, the paper loaded in the paper feed cassettes 43 of the paper feed units 5 and 6 is drawn by the pickup roller 35 and is sandwiched and transported between the feed roller 36 and the press roller 37. The transported paper is transported along the paper guide, and is sandwiched between the feed roller 38 and the press roller 39 and transported to the recording unit 3. As described above, the sheet conveyed to the recording unit 3 is conveyed between the transfer roller 31 and the photosensitive drum 32 to transfer the toner image, and is sandwiched between the fixing roller 33 and the press roller 34 so that the toner image is transferred. After being fixed, the paper is sandwiched between the discharge roller 40 and the press roller 41 and is carried out to the paper discharge tray 42.

  2 is an external perspective view showing a state in which the document tray 10 of the image reading apparatus A is opened, and FIG. 3 is a top view in a state in which the document tray 10 is closed. A document is set on the upper surface of the document tray 10 with the document tray 10 closed. However, when a read document discharged to the document discharge tray 22 is taken out, the document tray 10 is rotated upward to open the document. To take out. The outer periphery of the document tray 10 needs to be able to confirm the presence or absence of the document discharged to the discharge tray. Therefore, a translucent bottom cover 10 a formed integrally with the outer peripheral portion of the document tray 10 is detachably attached to the bottom surface of the document tray 10.

  A pair of bearing bodies (not shown) are formed in a protruding shape on both sides of the document tray 10 on the upper portion of the main body portion 7 of the image reading apparatus A. Rotating shaft bodies 100 and 101 are formed on both sides of the document tray 10. Is protruded to the side, and the rotary shaft bodies 100 and 101 are respectively attached to the bearing bodies, so that the document tray 10 is rotatably attached to the upper portion of the main body portion 7. Document guides 102 and 103 are attached to the upper surface of the document tray 10, and projecting portions 102a and 103a on the bottom surface are slidably provided in the guide grooves 104 and 105, respectively.

  FIG. 4 is a bottom view of the document tray 10 with the translucent bottom cover 10a removed. A gear 106 that is rotatably attached is provided at a substantially central portion of the bottom surface of the document tray 10. Narrow rack plates 107 and 108 are disposed on both sides of the gear 106. The rack plates 107 and 108 are arranged along the axial direction of the rotation axis of the document tray 10, and rack teeth having a predetermined length are formed at the side end portions facing the gear 106.

  The rack plate 107 is fitted into guide rail portions 109a to 109d formed in a convex shape along the axial direction of the rotation axis of the document tray 10, and slides in the axial direction. The guide rail portions 109a and 109b are formed in parallel with the rack plate 107 at substantially the same interval, and a guide groove 105 is drilled in parallel along the guide rail portions 109a and 109b. The guide rail portions 109c and 109d are formed in parallel with the extension of the guide rail portions 109a and 109b.

  When the rack plate 107 slides between the guide rail portions 109a to 109d, the rack teeth are arranged so as to mesh with the gear 106, and when the rack plate 107 is slid, the gear 106 rotates accordingly. . Further, an engagement protrusion 103a that is suspended from the bottom surface of the document guide 103 is fitted into one end portion of the rack plate 107. When the document guide 103 is moved along the guide groove 105, the rack is interlocked with it. The plate 107 slides.

  The rack plate 108 is fitted in guide rail portions 110a to 110d formed in a convex shape along the axial direction of the rotation axis of the document tray 10, and slides in the axial direction. The guide rail portions 110a and 110b are formed in parallel at substantially the same interval as the rack plate 108, and a guide groove 104 is drilled in parallel along the guide rail portions 110a and 110b. And the guide rail parts 110c and 110d are formed in parallel on the extension of the guide rail parts 110a and 110b.

  When the rack plate 108 slides between the guide rail portions 110a to 110d, the rack teeth are arranged so as to mesh with the gear 106. When the rack plate 108 is slid, the gear 106 also rotates accordingly. . Further, an engagement protrusion 102a suspended from the bottom surface of the document guide 102 is fitted into one end portion of the rack plate 108. When the document guide 102 is moved along the guide groove 104, the rack is interlocked therewith. The plate 108 slides.

  With the configuration described above, when one of the document guides 102 and 103 is moved in accordance with the size of the document, one of the rack plates 107 and 108 slides in conjunction with the movement. Since the plates 107 and 108 are connected via a gear 106, when one document guide is moved toward the center, the other document guide is also moved toward the center in conjunction therewith. Conversely, when one document guide is moved in a direction away from the center, the other document guide is also moved in a direction away from the center, so that the document can be easily aligned.

  Since the size of the document can be detected by detecting the setting position of the document guide, a detection mechanism for detecting the setting position of the rack plate interlocked with the document guide is provided on both sides of the gear 106.

  As a detection mechanism for the setting position of the rack plate 107, a guide bar 111 and a light detection unit 112 are provided. The guide bar 111 is disposed along a direction orthogonal to the longitudinal direction of the rack plate 107, and although not shown, the guide bar 111 is fitted in a rail portion formed on the frame of the document tray 10 and orthogonally crossed. It comes to slide on. A light shielding portion 111a is integrally formed at the end portion on the light detection portion 112 side, and an engaging protrusion 111b is provided on the rack plate 107 side. A guide groove 107 a is formed in the rack plate 107 in the longitudinal direction, and the engagement protrusion 111 b is engaged with the guide groove 107. Therefore, when the rack plate 107 slides, the engagement protrusion 11b relatively moves in the guide groove 107a.

  The guide groove 107a is formed with a straight line portion close to the rack teeth and a straight line portion separated from the rack teeth. When the engaging protrusion 111b reaches the straight line portion close to the rack teeth, the guide bar 111 is lighted. Moving to the detection unit 112 side (downward in the drawing in FIG. 4), the light shielding unit 111a is set to a position where the light detection unit 112 is shielded. Further, when the engaging protrusion 111b reaches a linear portion separated from the rack teeth, the guide bar 111 moves to the rack plate 107 side (upward in the drawing in FIG. 4), and the light shielding portion 111a is separated from the light detecting portion 112. The position is set so as not to block light.

  FIG. 5 is an explanatory diagram regarding the operation of the guide bar 111 and the light detection unit 112. The state where the light blocking unit 111 a of the guide bar 111 is separated from the light detection unit 112 (FIG. 5A) and the light detection unit 112 are blocked. The state (FIG. 5B) is shown. The light detection unit 112 includes a light emitting unit 112a that supports a light emitting element and a light receiving unit 112b that supports a light receiving element. The light detecting unit 112 and the light receiving element are arranged and supported so as to face each other. The light emitting unit 112a and the light receiving unit 112b are formed so as to protrude toward the light shielding unit 111a, and a predetermined interval is provided between them.

  The light shielding part 111a of the guide bar 111 is formed in a plate-like body standing on a support part 111c protruding in a direction orthogonal to the longitudinal direction of the guide bar 111, and has an eaves-like external light shielding at its upper end part. The part 111d is integrally formed. By moving the light shielding part 111a of the guide bar 111 as described above, the light shielding part 111a is moved between the light emitting part 112a and the light receiving part 112b, and the light of the light emitting element is blocked or allowed to pass through. ing.

  By projecting the light emitting portion 112a and the light receiving portion 112b toward the light shielding portion 111a, the protruding length can be increased, and therefore the width of the light shielding portion 111a can be set wide, so that light can be reliably shielded. become able to. When the light emitting unit 112a and the light receiving unit 112b are set to stand up from the bottom surface of the document tray 10, it is necessary to make the document tray 10 thicker by that amount. However, as described above, the document tray 10 is laid on the bottom surface. By setting, the thickness of the document tray 10 can be set thin.

  In addition, the external light shielding part 111d formed in an eave shape at the upper end of the light shielding part 111a is formed to have a size covering the entire upper surface of the light emitting part 112a and the light receiving part 112b, and the light shielding part 111a is formed as a light emitting part. When the light of the light emitting element is blocked by being inserted between the light 112a and the light receiving part 112b, the external light incident direction of the light emitting part 112a and the light receiving part 112b is covered to reliably shield the light from entering the light receiving element. Prevents false detection of the light receiving element.

  Since the external light shielding part 111d is integrally formed with the light shielding part 111a in this way, the detection operation can be performed reliably without using a separate part for shielding the external light, and the detection mechanism can be made compact. It becomes possible. In the present embodiment, the semi-transparent bottom cover 10a is used. However, even when external light is incident on the inside due to the semi-transparency, the external light shielding unit reliably shields the document. Will not occur. Therefore, the material used for the cover of the document tray 10 can be freely selected, and the degree of freedom of design such as design and shape can be increased.

  The detection mechanism of the setting position of the rack plate 108 is the same as the detection mechanism of the rack plate 107 described above, and a guide bar 113 and a light detection unit 114 are provided. Then, the engaging projection 113b of the guide bar 113 slides relatively in the guide groove 108a of the rack plate 108, so that the light shielding portion 113a of the guide bar 113 closes the light detecting portion 114 and shields the light and the position. It moves away from the detection unit 114 to a position where it is not shielded from light.

  The document size is detected by a combination of detection signals from the light detection units 112 and 114.

  FIG. 6 shows a modified example of the external light shielding part integrally formed with the light shielding part 111a. Side wall parts 111e are vertically provided on both sides of the eaves-like external light shielding part 111d, and both side wall parts 111e are further provided. A front wall 111f is formed between the two. Therefore, when the light shielding unit 111a is inserted between the light emitting unit 112a and the light receiving unit 112b, not only the upper surface of the light emitting unit 112a and the light receiving unit 112b but also the side surface and the front surface are covered. Therefore, it is possible to prevent the incidence of external light from various directions, and it is possible to more reliably exhibit the effect of shielding external light.

1 is a schematic sectional view of an entire image forming apparatus to which an embodiment according to the present invention can be applied. FIG. 3 is an external perspective view of the image reading apparatus showing an open state of the document tray. FIG. 3 is a top view relating to an image reading apparatus showing a state where a document tray is opened. FIG. 6 is a bottom view of the document tray with the bottom cover removed. It is explanatory drawing regarding operation | movement of a guide bar and a light detection part. It is explanatory drawing regarding the modification of an external light shielding part.

Explanation of symbols

A Image Reading Apparatus 1 Document Conveying Unit 2 Document Reading Unit 3 Recording Unit 4 Paper Conveying Unit 5 Paper Feeding Unit 6 Paper Feeding Unit 7
10 Document tray
100 rotating shaft
101 Rotating shaft
102 Document guide
103 Document Guide
104 Guide groove
105 Guide groove
106 gears
107 Rack board
108 rack board
109 Guide rail
110 Guide rail
111 Guide bar
111a Shading part
111d Outside light shield
112 Light detector
113 Guide bar
114 Light detector

Claims (4)

  A support member arranged so that a pair of the light emitting element and the light receiving element are opposed to each other; and a light shielding member that moves between the light emitting element and the light receiving element, wherein the light shielding member is external light that covers the light receiving element. A light detection mechanism in which a shielding part is integrally formed.   The light detection mechanism according to claim 1, wherein the outside light shielding portion is formed in an eaves shape at an end portion of the light shielding member.   An image reading apparatus including a document placement table and a main body that rotatably holds the document placement table, wherein a pair of light emitting elements and light receiving elements are opposed to each other on the bottom surface of the document placement table. An arranged support member and a light shielding member that moves in and out between the light emitting element and the light receiving element in conjunction with the document guide are disposed, and the light shielding member has an external light shielding portion that covers the light receiving element. An image reading apparatus which is integrally formed.   The image reading apparatus according to claim 3, wherein the external light shielding portion is formed in an eaves shape along a bottom surface of the document placing table at a lower end of the light shielding member.

Images