JP6497944B2 - Image reading device, light guide, irradiation device - Google Patents

Description

  The present invention relates to an irradiation apparatus that is provided in an image reading apparatus and irradiates a target such as a document with light when reading the image.

  The image reading device reads characters and images (hereinafter simply referred to as “images”) drawn on the object by irradiating the object with light and receiving the reflected light. For this purpose, the image reading apparatus includes an irradiation device that irradiates light and a light receiving device. FIG. 7 is a structural example diagram of a conventional irradiation apparatus. The irradiation device 7 includes an LED (Light Emitting Diode) element 700 and a light guide 702 that are light emitting units. The LED elements 700 are arranged in an array on the LED substrate 701. The light guide 702 has a main deflection surface 705. A light beam 707 emitted from the LED element 700 is incident from the incident surface 703 of the light guide 702 and guided to the main deflection surface 705 while repeating total reflection on the inner wall of the light guide 702. The main deflection surface 705 deflects the light beam 707 and emits it from the emission surface 706. A light beam 708 emitted from the emission surface 706 irradiates the object (document D in FIG. 7).

  Patent Document 1 discloses an invention of such an irradiation device (light source device). The irradiation device of Patent Document 1 forms a plurality of microlenses on a main deflection surface (reflection surface). This makes it possible to uniformly diffuse light inside the light guide (light guide) and read a glossy object or an object with high reflectivity.

JP 2011-65864 A

  In the irradiation apparatus having such a configuration, it is desirable that the main deflection surface 705 deflects the light beam 707 by total reflection. However, the light beam 707 generally has a light distribution characteristic represented by a Gaussian intensity distribution. Accordingly, a part of the light beam 707 may leak from the main deflection surface 705 to the outside of the light guide 702 without satisfying the critical angle, which is a condition that the incident angle to the main deflection unit causes total reflection. In this specification, light leaking from the surface other than the emission surface 706 to the outside of the light guide 702 is referred to as “leakage light”.

  The leaked light 711 becomes harmful light when it reaches the document D or the light receiving device, and causes a defective read image such as stray light (ghost) or flare. In order to prevent such image defects, conventionally, for example, leakage light 711 is shielded by a light shielding member 709 so as not to be harmful light. However, since the light shielding member 709 cannot make the reflectance 0%, it is difficult to completely eliminate the influence of the leakage light 711. In addition, a low reflection member such as flocking paper can be used for the light shielding member 709. However, in this case, the cost is high and it is not a practical solution. Further, the amount of light that irradiates the object is reduced by the leakage light 711.

The present invention, in order to solve the above problems, and an object thereof to reduce the loss of light quantity you illuminating the object.

The image reading apparatus of the present invention for solving the above problems, the object has a light guide for deflecting toward the object light from the plurality of light emitting elements and the plurality of light emitting elements arranged in an array comprising an irradiation unit for irradiating, with a light receiving means for receiving reflected light reflected by the object, said light guide includes an incident surface, the entering slope light from said plurality of light emitting elements is incident an exit surface, and the light guide portion having a main deflecting surface for deflecting toward the light incident from the incident surface to the exit surface of the incident the light emitted toward the object from the main deflection A plurality of light emitting elements arranged in an array , the second light guide unit configured to deflect the leaked light that has passed through the surface and leaked to the outside of the light guide toward the object. Arranged to face the incident surface provided in the longitudinal direction of the body, 2 The light guide part is integral with the light guide part, forms a rib shape extending in the longitudinal direction of the light guide, and an incident boundary surface on which leaked light leaks outside the light guide characterized Rukoto to have a an exit boundary surface to polarize the incident light from the incident surface and.

According to the present invention, by deflected toward the object by the main deflecting surface passes through the main deflecting surface without being deflected by the second light guiding unit the leakage light leaking to the outside of the light guide, the object the loss of the irradiated light intensity low lessen can Rukoto.

1 is a configuration diagram of an image reading apparatus. The block diagram of an optical unit. (A)-(c) is a block diagram of an irradiation part. (A), (b) is explanatory drawing of the deflection | deviation of the leakage light beam by a sub deflection | deviation part. (A), (b) is another example figure of an irradiation part. Another example of an irradiation part. The structural example figure of the conventional irradiation apparatus.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of an image reading apparatus according to the present embodiment. The image reading apparatus 1 includes a reader unit 10 and an original table glass 20. The image reading apparatus 1 can be used for a copying machine, an image scanner, a multifunction printer, and the like. On the platen glass 20, a document D as an object is placed with the reading surface on which an image is formed facing down. The reader unit 10 includes an irradiation unit 30, an optical unit 40, a light receiving unit 50, and a moving unit 60.

  The irradiating unit 30 irradiates the document D placed on the document table glass 20 with light. The optical unit 40 condenses the reflected light of the light irradiated on the document D on the light receiving surface of the light receiving unit 50. The light receiving unit 50 includes a CCD (Charge Coupled Device) element or the like. The light receiving unit 50 performs photoelectric conversion of the reflected light received by the light receiving surface and outputs an electrical signal. The electric signal is a signal generated by reading an image of the document D. The moving unit 60 is driven by the motor 70 to move the optical unit 40 in the scanning direction represented by the arrow in FIG. Since the optical unit 40 and the irradiation unit 30 are integrally formed, the irradiation unit 30 moves in the scanning direction as the optical unit 40 moves.

  When reading an image from the document D, the light emitted from the irradiation unit 30 is reflected by the document D. The light receiving unit 50 receives the reflected light reflected by the document D via the optical unit 40. The light receiving unit 50 generates and outputs an electrical signal from the received reflected light. The image reading apparatus 1 reads the image from the entire reading surface of the document D by performing the above processing while the irradiation unit 30 and the optical unit 40 reciprocate in the scanning direction by the moving unit 60.

  FIG. 2 is a configuration diagram of the optical unit 40. The optical unit 40 includes a plurality of plane mirrors 401 a to 401 d and a condenser lens 402. The plane mirrors 401 a to 401 d are optical systems that guide reflected light from the document D to the condenser lens 402. The condensing lens 402 focuses the reflected light guided by the plane mirrors 401 a to 401 d on the light receiving surface of the light receiving unit 50 to form an image.

  FIG. 3 is a configuration diagram of the irradiation unit 30. FIG. 3A shows the overall configuration of the irradiation unit 30. The irradiation unit 30 includes a light emitting unit 31 serving as a light source and a light guide 32. FIG. 3B is a view of the irradiation unit 30 as viewed from the document table glass 20 side, and FIG. 3C shows the configuration of the light guide 32.

  The light emitting unit 31 is configured by arranging LED elements 100 as light emitting elements on an LED substrate 101 in an array. In the example of FIG. 3A, a plurality of LED elements 100 are linearly arranged in the depth direction in the drawing. The LED element 100 is a side irradiation type LED. The LED substrate 101 is attached to the light guide 32.

  The light guide 32 is made of a highly transmissive material such as acrylic resin. The light guide 32 includes an incident surface 103 on which light is incident, a main deflection surface 105 that deflects light, a light guide unit 104 that guides light from the incident surface 103 to the main deflection surface 105, an exit surface 106 that emits light, and It has the sub deflection | deviation part 110 used as a 2nd light guide part. Since the LED elements 100 are arranged in an array, light enters from the incident surface 103 as a linear light flux 107. The light guide unit 104 guides the light beam 107 to the main deflection surface 105 while repeating total reflection. The main deflection surface 105 deflects the light beam 107 toward the emission surface 106 as a main light beam 108. The main light beam 108 is emitted from the emission surface 106 toward the document D. The sub-deflecting unit 110 deflects the leaked light beam 111 that is the leaked light leaked without being deflected by the main deflection surface 105 toward the document D.

In general, the light beam 107 has a light distribution characteristic of a Gaussian distribution, and most of the main deflection surface 105 is deflected toward the emission surface 206 and emitted as the main light beam 108, and the remaining portion is deflected by the main deflection surface 105. Without passing through the main deflection surface 105 and leaking as a leaked light beam 111. The leakage light beam 111 is incident on the sub deflection unit 110. The sub-deflecting unit 110 is configured integrally with the light guide 32 and has a rib shape extending in the longitudinal direction of the light guide 32. FIG. 4 is an explanatory diagram of the deflection of the leaked light beam 111 by the sub deflection unit 110. As shown in FIG. 4A, the sub-deflecting unit 110 leaks the light flux at the incident interface 112 where the light flux 111 is incident, depending on the incident angle and the refractive index n determined according to the material of the light guide 32. 111 is deflected (refracted) according to the following relational expression.
sin θ2 = sin θ1 / n
θ1: Incident angle, θ2: Output angle, n: Refractive index of light guide

  As shown in FIG. 4B, the sub-deflecting unit 110 similarly deflects (refracts) the leaking light beam 111 on the output boundary surface 113 that emits the leaking light beam 111. The sub-deflecting unit 110 refracts the leakage light beam 111 to return to the main light beam 108 deflected by the main deflection surface 105 by the deflection at the entrance boundary surface 112 and the exit boundary surface 113. As a result, the leakage light beam 111 irradiates the same part as the part on the original D irradiated by the main light beam 108.

  The document D is irradiated linearly by the main light beam 108 and the leakage light beam 111. Therefore, the image reading apparatus 1 can read the document D line by line with the arrangement direction of the LED elements 100 as the scanning direction and the moving direction of the irradiation unit 30 and the optical unit 40 as the sub-scanning direction.

  The irradiation unit 30 having such a configuration can improve the illumination efficiency in order to use the leakage light beam 111 that has been conventionally removed as light for irradiating the document D. Therefore, the irradiation unit 30 can ensure a sufficient amount of light for reading an image even if the number of LED elements 100 is reduced. Since the image reading apparatus 1 prevents stray light and flare due to the leaked light beam 111, the image reading apparatus 1 can read the document D while suppressing the occurrence of image defects.

  FIG. 5 is another example of the irradiation unit. FIG. 5A shows the overall configuration of the irradiation unit 33. FIG. 5B is a perspective view of the light guide 34. The irradiation unit 33 in FIG. 5 is different from the irradiation unit 30 in FIG. 3 in that the configuration of the light guide 34 and the reflection plate 116 are used.

The light guide 34 is provided with the main deflection surface 105 so that a part of the light beam 107 passes through the light guide 104 and leaks as it is without reaching the main deflection surface 105. A light beam that passes through the light guide unit 104 and leaks as it is is referred to as a second leakage light beam 115. The second leakage light beam 115 is guided to the reflection plate 116. The leakage surface 117 from which the second leakage light beam 115 is emitted is a toric surface in order to reduce irradiation unevenness caused by the bright spot interval of the LED element 100, and fine irregularities are formed.
5 is configured to deflect (refract) the leaked light beam 111 in the direction of the reflecting plate 116, not in the direction of the document D. The sub-deflecting unit 114 returns the leakage light beam 111 to the second leakage light beam 115 by such a configuration.

  The reflector 116 is disposed at a position facing the light guide 34 with a gap 118 serving as an optical path for the reflected light reflected by the document D being guided to the flat mirror 401a of the optical unit 40. The reflector 116 reflects the second leaked light beam 115 and the leaked light beam 111 incident from the sub deflection unit 114 toward the document D. As described above, the sub-deflecting unit 114 and the reflecting plate 116 serve as a second light guiding unit that deflects the light flux leaking from the light guiding unit 104 toward the document D.

  5 irradiates the document D by deflecting a part of the light beam 107 emitted from the LED element 100 by the main deflection surface 105 and reflecting the remaining part by the reflecting plate 116. Therefore, the irradiation unit 33 can improve the illumination efficiency and ensure a sufficient amount of light for image reading even if the number of LED elements 100 is reduced. Since the image reading apparatus 1 prevents stray light and flare caused by the leakage light beam 111 and the second leakage light beam 115, the image reading apparatus 1 can read the document D while suppressing the occurrence of image defects. Further, since the leakage surface 117 that leaks the second leakage light beam 115 out of the remaining portion of the light beam 107 is formed to be uneven, it is possible to reduce irradiation unevenness due to the second leakage light beam 115.

  FIG. 6 is another exemplary diagram of the irradiation unit. The irradiation unit 35 in FIG. 6 differs from the irradiation unit 30 in FIG. 3 in the configuration of a sub deflection unit 119 that is a second light guide unit configured integrally with the light guide 36.

  The sub-deflecting unit 119 may deflect the leakage light beam 111 toward the document D in the same manner as the sub-deflecting unit 110 in FIG. 4, but deflects it toward the reflecting plate 116 like the sub-deflecting unit 114 in FIG. It may be a configuration. At least one of the incident boundary surface 120 on which the leaked light beam 111 of the sub-deflecting unit 119 is incident and the output boundary surface 121 that emits the leaked light beam 111 is subjected to graining. The leakage light beam 111 is optically diffused by the surface subjected to the texture processing. The leakage light beam 111 irradiates the document D through an optical path different from that of the main light beam 108 deflected by the main deflection surface 105. Since the leakage light beam 111 does not pass through the leakage surface 117 which is the toric surface in FIG. 5B, the leakage light beam 111 reaches the document D while the irradiation unevenness caused by the arrangement interval of the LED elements 100 remains. In FIG. 6, irradiation unevenness caused by the arrangement interval of the LED elements 100 can be reduced by subjecting at least one of the incident boundary surface 120 and the emission boundary surface 121 of the sub-deflecting unit 119.

  DESCRIPTION OF SYMBOLS 1 ... Image reading apparatus, 10 ... Reader unit, 20 ... Original plate glass, 30, 33, 35 ... Irradiation part, 40 ... Optical unit, 50 ... Light receiving part, 60 ... Moving part, 70 ... Motor, 31 ... Light emission part, 32, 34, 36 ... light guide, 100 ... LED element, 104 ... light guide, 110, 114, 119 ... sub deflection part, 116 ... reflector, D ... document

Claims (6)

An irradiation unit for irradiating said object with a light guide for deflecting toward the object light from the plurality of light emitting elements and the plurality of light emitting elements arranged in an array,
Light receiving means for receiving the reflected light reflected by the object ,
The light guide is
Emitting surface, and the exit surface is incident the light from the incident surface for emitting incident surface which light from the plurality of light emitting elements is incident, a front the light incident from the entry slope toward the object A light guide having a main deflection surface that deflects toward the
A second light guide part that deflects the leaked light that has passed through the main deflection surface and leaked to the outside of the light guide toward the object ,
The plurality of light emitting elements arranged in the array are arranged to face the incident surface provided in the longitudinal direction of the light guide,
The second light guide part is integral with the light guide part, has a rib shape extending in the longitudinal direction of the light guide, and enters the leaked light leaked to the outside of the light guide. characterized Rukoto to have a boundary surface and an exit boundary surface to polarize the incident light from the incident surface,
Image reading device. The second light guide unit deflects the leaked light toward the object by refracting the leaked light at the incident interface and the output interface.
The image reading apparatus according to claim 1. The second light guide unit is characterized in that at least one of the incident boundary surface and the emission boundary surface is textured.
  The image reading apparatus according to claim 2.   The emission surface and the emission boundary surface are continuous,
  The image reading apparatus according to claim 1. A plurality of light emitting elements arranged in an array, an incident surface on which light from the plurality of light emitting elements is incident, an exit surface that emits the light incident from the entrance slope toward an object, and the incident surface A light guide unit having a main deflection surface for deflecting the light incident from the light source toward the exit surface;
A second light guide part that deflects leaked light that has passed through the main deflection surface and leaked to the outside toward the object, and a light guide comprising:
The incident surface provided in the longitudinal direction of the light guide is arranged to face the plurality of light emitting elements arranged in the array,
The second light guide part is integral with the light guide part, has a rib shape extending in the longitudinal direction of the light guide, and enters the leaked light leaked to the outside of the light guide. characterized Rukoto to have a boundary surface and an exit boundary surface to polarize the incident light from the incident surface,
Light guide. A plurality of light emitting elements arranged in an array, and a light guide that deflects light from the plurality of light emitting elements toward an object,
The light guide is
An incident surface on which light from the plurality of light emitting elements is incident, an exit surface that emits the light incident from the entrance slope toward an object, and the light incident from the incident surface on the exit surface A light guide having a main deflection surface that deflects toward the
A second light guide part that deflects the leaked light that has passed through the main deflection surface and leaked to the outside of the light guide toward the object,
The plurality of light emitting elements arranged in the array are arranged to face the incident surface provided in the longitudinal direction of the light guide,
The second light guide part is integral with the light guide part, has a rib shape extending in the longitudinal direction of the light guide, and enters the leaked light leaked to the outside of the light guide. It has a boundary surface and an output boundary surface that polarizes light incident from the incident surface,
Irradiation device.