JP5618637B2 - Document reading light source device - Google Patents

Description

  The present invention relates to a document reading light source device, and more particularly to a document reading light source device used as a light source in a document reading device such as a scanner.

  Conventionally, reading of a document in a reduction optical system, a contact optical system scanner, or the like is performed by scanning and irradiating linear light having a predetermined width on an image surface of a document to be read placed on a contact glass, The transmitted light is imaged on a linear solid-state image sensor (line CCD) through an optical system composed of optical elements such as a mirror and a lens, and an image signal output from the linear solid-state image sensor is processed by signal processing. The image is read.

  At this time, when the document image is a color image, in order to read the color document image with high definition, linear light that irradiates the image surface of the read document with high illuminance and uniform illuminance distribution is required. A light source device for realizing a linear light is required.

  As a conventional example of a light source device, as shown in FIG. 11, light emitted from a small area of each of a plurality of LED light sources 80 is reflected by a mirror 81 and reflected light is contact glass 82 and a read original 83. The reflected light (reflected light including the document image) reflected on the image surface of the document 83 to be read is reflected by the mirror 85 on the imaging surface of the line sensor 86 as a photoelectric conversion element. Is formed as a reduced image of the original image (see, for example, Patent Document 1).

JP 2008-304860 A

  By the way, since the optical element (mirror 81) is arrange | positioned in the light source apparatus which consists of the said structure in the optical path until the light radiate | emitted from the LED light source 80 is irradiated to the to-be-irradiated part 84, the optical path length between them is long. Thus, the optical loss in the optical path increases. As a result, the utilization efficiency of the light emitted from the LED light source 80 is reduced, the amount of irradiation light contributing to the reading of the original is reduced, and a clear original image may not be formed on the imaging surface of the line sensor 86. is there.

  Accordingly, the present invention has been made in view of the above problems, and the object of the present invention is to irradiate light to be read with high illuminance and good illuminance distribution with good light utilization efficiency. An object of the present invention is to provide a document reading light source device.

In order to solve the above-described problem, the invention described in claim 1 of the present invention is a long flat plate-like light guide body and a predetermined interval along one end face along the longitudinal direction of the light guide body. And it has a plurality of LED light sources arranged with the irradiation direction facing the end face, and the light guide has a flat plate-like one surface with respect to the central axis along the short direction of the light guide. A plurality of mirror-inclined surfaces rising in a predetermined angle toward the end face side and extending along the longitudinal direction of the light guide are provided side by side , and a plurality of triangular prisms or arc column prisms are provided on the other flat surface. The cut is a prism cut surface arranged in parallel in the short direction of the light guide, and is specularly reflected parallel to the extending direction of the prism cut surface at a position facing the prism cut surface with a gap of a predetermined width. A surface is provided.

Further, the invention described in claim 2 of the present invention is characterized in that the long flat plate-like light guide and the end face with the irradiation direction at a predetermined interval along one end face along the longitudinal direction of the light guide. A plurality of LED light sources arranged toward the front surface, and the light guide has a flat plate-like one surface with the end surface at a predetermined angle with respect to a central axis along a short direction of the light guide. A plurality of mirror inclined surfaces rising in the longitudinal direction of the light guide are provided in parallel, and a plurality of triangular prisms or arc-shaped prism cuts are formed on the other surface of the flat plate. A prism cut surface arranged side by side in the short direction, and a mirror reflection surface is disposed in parallel to the extending direction of the prism cut surface at a position facing the prism cut surface with a gap having a predetermined width , A plurality of triangular prisms are provided on the end surface opposite to the end surface on which the plurality of LED light sources are disposed. Or characterized in that the arc columnar prisms cut are juxtaposed in the thickness direction of the light guide body.

Moreover, the invention described in claim 3 of the present invention is that in claim 1 or claim 2, of the plurality of mirror surface inclined surfaces, the mirror surface inclined surfaces adjacent to each other are in the short direction of the light guide. The rising inclination angle with respect to the central axis along the axis is the same, or the mirror surface inclined surface located on the LED light source side has a smaller inclination angle .

Moreover, the invention described in claim 4 of the present invention is any one of claims 1 to 3, wherein the light guide is made of a transparent resin, and the short-side direction of the light guide on the mirror surface is inclined. The rising inclination angle with respect to the central axis along the axis is in the range of 24 ° to 25 ° .

  The document reading light source device of the present invention has a plurality of LED light sources arranged in the vicinity of one end surface along the longitudinal direction of a long flat light guide, and rises toward the LED light source side on at least one flat surface. A plurality of mirror-surface inclined surfaces extending along the longitudinal direction are arranged side by side, and a structure is provided in which a mirror-reflection surface is disposed at a position facing the other flat surface with a gap.

  As a result, the light condensing performance is enhanced by the highly condensing light emitted from the LED light source and guided without being reflected in the light guide, and reflected by the mirror inclined surface and emitted to the gap. Therefore, it is possible to realize a document reading light source device that is capable of irradiating high-illuminance linear light onto an image surface of a document to be read.

1 is a schematic perspective view of an embodiment according to the present invention. Similarly, it is a schematic sectional drawing of the embodiment concerning the present invention. It is an optical path explanatory drawing concerning a light guide. Similarly, it is an optical path explanatory drawing concerning a light guide. Similarly, it is an optical path explanatory drawing concerning a light guide. Similarly, it is an optical path explanatory drawing concerning a light guide. Similarly, it is an optical path explanatory drawing concerning a light guide. It is explanatory drawing of a light guide. Similarly, it is explanatory drawing of a light guide. It is explanatory drawing of the original reading apparatus using the light source device for original reading of this invention. It is explanatory drawing of a prior art example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 10 (the same parts are denoted by the same reference numerals). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

    1 and 2 schematically show a schematic structure of a document reading light source device according to the present embodiment. FIG. 1 is a perspective view, and FIG. 2 is a cross-sectional view.

  The document reading light source device 1 mainly includes a substrate 2, an LED light source 5, a light guide 10, a reflecting member 20, and a lamp house 30. Among them, the substrate 2 has a long shape, and a conductive pattern (not shown) is formed on at least one surface of the substrate 2 and extends from the conductive pattern to be electrically connected to the electrode of the LED light source 5 ( (Not shown) is formed.

  The LED light source 5 is a so-called side view type that irradiates the irradiation light substantially parallel to the surface of the substrate when mounted on the substrate 2, and is a blue LED element that emits blue light to the light emission source. (Hereinafter abbreviated as an LED element) 6, and a resin-sealed structure in which the LED element 6 is covered with a sealing resin 7 in which a phosphor is mixed in a translucent resin.

  In this case, the phosphor mixed in the translucent resin is a yellow or yellow-green phosphor that is wavelength-converted into yellow or yellow-green light that is excited by blue light emitted from the LED element 6 and has a blue complementary color. A part of the blue light emitted from the LED element, and a part of the blue light emitted from the LED element, and a part of the blue light emitted from the LED element. Pseudo white light is generated by additive color mixing.

  As for the phosphor, a mixed phosphor obtained by mixing a green phosphor and a red phosphor, which are excited by blue light and wavelength-converted into green light and red light, respectively, is used, and one of the blue light emitted from the LED element 6 is used. It is also possible to generate white light by additive color mixture of green light and red light whose wavelengths have been converted by exciting the mixed phosphor and a part of the blue light emitted from the LED element 6.

  The light guide 10 is made of a transparent resin material such as acrylic and has a long flat plate shape. Of the end faces facing each other along the longitudinal direction, one end face is a light incident face 11 and the other end face is light. The light exit surface 12 is used.

  In addition, one of the opposing flat surfaces of the light guide 10 is a mirror flat surface 13 and the other surface is incident at a predetermined angle with respect to the central axis Z along the short side direction. Each of the plurality of specular inclined surfaces 14 rising toward the surface 11 is a prism surface 15 extending in parallel along the longitudinal direction.

  The reflecting member 20 has a specular reflecting surface 21, and the reflecting surface 21 is entirely formed of a reflecting metal film such as silver (Ag), or a resin film such as silver (Ag). The reflective metal film is provided.

  The lamp house 30 is preferably made of a highly light-shielding material, and in the present embodiment, a white polycarbonate resin material having light shielding properties as well as light shielding properties is used, and has a cross-sectional shape in the short direction and a bottomed opening. It has a long shape that is substantially U-shaped, and has a recess 31 inside.

  The document reading light source device 1 is assembled in the structure described below using the above-described components.

  That is, a plurality of side view type LED light sources 5 are mounted at a predetermined interval along the longitudinal direction of the substrate 2 on one side in the short direction of the long substrate 2. It arrange | positions so that irradiation light may be irradiated to the other side substantially parallel to a substrate surface.

  Further, on the other side of the substrate 2 in the short direction, a long light guide 10 is disposed along the longitudinal direction of the substrate 2 so that the prism surface 15 side is in contact with the substrate 2. At this time, the relationship between the LED light source 5 and the light guide 10 is such that a plurality of LED light sources 5 are arranged in the vicinity of the light incident surface 11 of the light guide 10 and at predetermined intervals along the light incident surface 11. The light emitting surface 8 of each LED light source 5 and the light incident surface 11 of the light guide 10 are opposed to each other. In addition, the height of the light emitting surface 8 of each LED light source 5 and the height of the light incident surface 11 of the light guide 10 are substantially the same, and the optical axis of the LED light source 5 and the short direction of the light guide 10 are set. The central axis Z of the light guide 10 along the thickness direction is positioned on a substantially straight line.

  And the board | substrate 2 with which the several LED light source 5 was mounted and the light guide 10 was arrange | positioned is accommodated in the recessed part 31 of the lamp house 30, and is being fixed. In this case, the substrate 2 is fixed in a state where the surface of the substrate 2 opposite to the mounting surface of the LED light source 5 is in contact with the inner surface 32 of the recess 31 of the lamp house 30.

  The light emitting surface 12 of the light guide 10 and the opening end 33 of the lamp house 30 are in a substantially flush relationship. Further, the reflecting member 20 is disposed above the mirror surface flat surface 13 of the light guide body 10 with the mirror surface reflection surface 21 facing the mirror surface flat surface 13 side of the light guide body 10. A gap 40 having a predetermined width is provided between the mirror surface 13 and the mirror surface 21 of the reflecting member 20.

  In addition, the mirror surface flat surface 13 and the mirror surface inclination surface 14 show a shape, and all process the shape of a transparent resin material. That is, a reflective film or the like is not formed as a mirror surface, but has a function of total reflection due to a difference in refractive index between resin and air.

  The above is the schematic structure of the light source device for document reading according to the present embodiment. Next, the optical path formation until the light emitted from the LED light source is emitted to the outside from the light source device for document reading, the optical system of the document reading device in which the light source device for document reading is used, and the document Description will be made based on further details of the reading light source device.

  FIG. 3 shows that light emitted from the LED light source 5 and incident into the light guide 10 from the light incident surface 11 of the light guide 10 is directly reflected from the light output surface 12 without being reflected in the light guide 10. It shows the optical path formation of the light emitted to the outside.

As described above, the light guide 10 is made of a transparent resin material and has a long flat plate shape. The specific dimensions of the long flat plate are as follows. The width w (distance between the light incident surface 11 and the light output surface 12) in the short direction is 4 mm, the thickness d is 0.8 mm, and the refractive index n of the transparent resin material. ₁ is 1.49.

Therefore, the light emitted from the LED light source 5 and incident from the light incident surface 11 of the light guide 10 is directly reflected on the light emitting surface 12 without being reflected in the light guide 10 in the thickness direction of the light guide 10. to reach, (the normal line N to a line perpendicular to the light entrance surface 11) of the incident light at the light incident surface 11 of the light guide 10 when the incident angle and theta _1, theta ₁ is theta ₁ ≦ tan ⁻¹ (d / 2 · w) is sufficient. Substituting the above d = 0.8 mm and w = 4 mm into this equation results in a range of θ ₁ ≦ 5.71 °.

  That is, light emitted from the LED light source 5 and incident from the light incident surface 11 of the light guide 10 at an angle of 5.71 ° or less with respect to the normal N is emitted without being reflected in the light guide 10. Reach plane 12.

Further, when the light reaching the light emitting surface 12 is emitted from the light emitting surface 12 into the atmosphere having a refractive index n ₂ of 1, the light is guided at the boundary surface between the light emitting surface 12 of the light guide 10 and the air. the angle of incidence of the guided light body 10 is theta _1, and the refractive angle of the refracted light is refracted emitted into the air and θ _2, θ ₂ is ^{_{θ 2 = sin -1 (n ·}} sinθ ₁ ). Substituting the above θ ₁ ≦ 5.71 ° into this formula results in θ ₂ ≦ 8.525 °.

  That is, the emitted light (refracted light) emitted from the light emitting surface 12 of the light guide 10 is emitted at an angle of 8.525 ° or less with respect to the normal line N. By the way, in order to efficiently read the original image with the reflected light of the irradiation light applied to the read original, it is necessary that the reflected light is imaged with a predetermined width on the light receiving surface of the CCD serving as the light receiving element. In order to secure this imaging width, it is required to set the irradiation width of the irradiation light on the image surface of the document to be read within 3 mm.

Therefore, in FIG. 3, the distance from the light emitting surface 12 of the light guide 10 is s, and the width of the irradiation light emitted from the light emitting surface 12 of the light guide 10 at an angle of θ ₂ or less with respect to the normal N. If a, then s = ((ad) / 2 · tan θ ₂ ). Substituting the irradiation width of 3 mm into a in this equation and substituting d = 0.8 and θ ₂ = 8.525 yields s = 7.338.

  Accordingly, the read original is positioned at a distance of 7.338 mm or less from the light emitting surface 12 of the light guide 10, so that the reflected light from the read original forms a clear image on the light receiving surface of the CCD. become.

  However, in the actual document reading apparatus, the document to be read 45 is placed on the contact glass 46 as shown in FIG. Therefore, the image surface 47 of the read original 45 is irradiated with refracted light that has passed through the contact glass 46. Therefore, the distance from the light emitting surface 12 of the light guide 10 to the image surface 47 of the document 45 to be read with respect to the irradiation width b of the irradiation light on the image surface 47 of the document 45 to be read is the optical distance of each document reader. It is set based on the system.

  The above is the description of the optical path formation of the light that has directly entered the light exit surface 12 without being reflected through the light guide 10 while being guided through the light entrance surface 11 of the light guide 10. If both surfaces of the light guide 10 are mirror-flat surfaces, the light incident on the light guide 10 and reflected (totally reflected) once or more during the light guide in the light guide 10 reaches the light exit surface 12. When the light exit surface 12 emits air to the atmosphere, the exit angle emitted from the light exit surface 12 of the light guide 10 into the air is the same as the incident angle at the light entrance surface 11. The angle with respect to the normal line N of the outgoing light emitted from the light exiting light emitted from the light outgoing face 12 is the light that has directly reached the light outgoing face 12 without being reflected in the light guide 10 while being guided. It becomes larger than the angle with respect to the normal N.

  Therefore, when both the flat plate-like surfaces of the light guide 10 are mirror-flat surfaces, the irradiation range of the irradiation light in the thickness direction of the light guide 10 is expanded, so that the light is appropriately condensed on the image surface of the document to be read. It becomes difficult to irradiate the irradiation light, and it becomes difficult to form a clear original image on the light receiving surface of the CCD by the reflected light from the read original.

Therefore, in the present invention, incident light having an incident angle θ _{1 on} the light incident surface 11 of the light guide 10 in a range of θ ₁ > tan ⁻¹ (d / 2 · w) is guided in the light guide 10. The condensed irradiation light is irradiated onto the image surface of the original to be read by reducing the emission angle when the light is reflected (total reflection) at least once and emitted from the light emission surface 12 into the atmosphere. .

  As a specific method, as described above, one surface of the light guide 10 is formed with a plurality of inclined mirror surfaces 14 rising toward the light incident surface side at a predetermined angle with respect to the central axis Z along the short direction. Each of them is a prism surface 15 extending along the longitudinal direction, and a specular reflection surface 21 is disposed above the specular flat surface 13 on the opposite side of the prism surface 15 of the light guide 10. A gap 40 having a predetermined width was provided between the surface 21 and the surface 21.

5 to 7 show specific detailed structures and light ray trajectories of the light guide 10, and α _{1 to 3} in the drawing are inclination angles at which the mirror inclined surface 14 rises with respect to the central axis Z, and β _{1. to 3} is when reflected by the mirror surface inclined surface 14 is incident from the light incident surface (total reflection) reflected light reaches the mirror flat surface 13, the angle of incidence relative to the normal N of said mirror surface flat surface 13, gamma _{1 ˜3} is a refraction angle with respect to the normal N when the reflected light that has reached the specular flat surface 13 is emitted to the gap 40.

  In any case, the light incident from the light incident surface 11 of the light guide 10 and reaching the mirror inclined surface 14 is set to be guided in the light guide 10 parallel to the central axis Z. .

Then, as shown in FIG. 5, when the inclination angle α ₁ of the mirror surface inclined surface 14 is set to 24 °, the reflected light incident from the light incident surface and reflected by the mirror surface inclined surface 14 has an incident angle β ₁ of 42 °. The light enters the specular flat surface 13, exits from the specular flat surface 13 to the gap 40 with a refraction angle γ ₁ of 85.56 °, and is directly irradiated from the original reading light source device or reflected by the specular reflection surface 21. Then, the reflected light is irradiated to the outside from the original reading light source device.

Further, as shown in FIG. 6, when the inclination angle α ₂ of the mirror inclined surface 14 is set to 24.5 °, the reflected light incident from the light incident surface and reflected by the mirror inclined surface 14 has an incident angle β ₂ of 41. The light enters the mirror surface flat surface 13 at an angle, exits from the mirror surface flat surface 13 to the gap 40 with a refraction angle γ ₂ of 77.83 °, and is irradiated as it is from the original reading light source device, or the mirror reflection surface 21. And the reflected light is irradiated to the outside from the original reading light source device.

Further, as shown in FIG. 7, when the inclination angle α ₃ of the mirror surface 14 is set to 25 °, the reflected light incident from the light incident surface and reflected by the mirror surface 14 has an incident angle β ₃ of 40 °. The light enters the specular flat surface 13 and exits from the flat specular surface 13 to the gap 40 at a refraction angle γ ₃ of 73.28 ° and is directly irradiated from the original reading light source device or reflected by the specular reflecting surface 21. Then, the reflected light is irradiated to the outside from the original reading light source device.

At the interface between the mirror-surface flat surface 13 of the light guide 10 having a refractive index n ₁ of 1.49 and the gap 40 having a refractive index n ₂ of 1, incident light incident on the interface from the light guide 10 side passes through the gap 40 from the interface. Τ = 42.155 °, where τ is the critical angle when emitting to the side. Therefore, the light directed toward the interface from the light guide 10 side is made incident at an incident angle β smaller than the critical angle τ and as close to the critical angle τ as possible, so that the light refracted at the interface and emitted to the gap 40 is refracted. The angle γ can be as close to 90 ° as possible.

  The fact that the refraction angle γ of the outgoing light exiting from the interface to the gap 40 approaches 90 °, in other words, the inclination angle of the outgoing light with respect to the central axis Z of the light guide 10 becomes smaller, and the outgoing light becomes the central axis Z. It means that the light is condensed to the side.

  Therefore, based on such a ray tracing result, the inclination angle α rising from the central axis Z of the mirror inclined surface 14 formed on the prism surface 15 of the light guide 10 is preferably in the range of 24 ° to 25 °. . However, the mirror inclined surface 14 does not necessarily have the same inclination angle α, and may be continuously changed between the light incident surface 11 and the light emitting surface 12, or the light incident surface 11 and the light emitting surface. 12 may be divided into a plurality of areas, and the inclination angle α may be different for each section.

  Further, when the mirror surface inclined surface 14 positioned on the light incident surface 11 side of the light guide 10 is compared with the mirror surface inclined surface 14 positioned on the light emitting surface 12 side, the mirror surface inclined surface 14 on the light incident surface 11 side is more preferable. However, light having a large incident angle α at the light incident surface 11 arrives. For this reason, the refraction angle γ of the light reflected (totally reflected) by the mirror inclined surface 14 on the light incident surface 11 side and emitted from the mirror flat surface 13 to the gap 40 is increased to increase the mirror inclined surface on the light emitting surface 12 side. In order to approximate the refraction angle γ of the light that is reflected (totally reflected) 14 and emitted from the mirror surface flat surface 13 to the gap 40, the inclination angle α of the mirror surface 14 on the light incident surface 11 side is reduced. This is possible.

  That is, among the plurality of mirror surface inclined surfaces, the mirror surface inclined surfaces adjacent to each other have the same rising inclination angle α with respect to the central axis along the short direction of the light guide or are positioned on the light incident surface (LED light source) side. It is preferable that the inclination angle α of the mirror inclined surface is small. In any case, the inclination angle α and the pitch of the mirror inclined surface 14 on the prism surface 15 are appropriately set in consideration of various requirements such as the shape, size, and optical characteristics of the light guide 10.

  Further, as much as possible, the angle α of the light emitted from the mirror flat surface 13 of the light guide 10 to the gap 40 and reflected by the mirror reflection surface 21 is irradiated outside the light source device before reaching the mirror flat surface again. It is preferable to set the angle as described above. This is because the light reflected by the specular reflection surface 21 and returning to the specular flat surface 13 is unlikely to become irradiation light that again enters the light guide 10 and contributes to the reading of the document to be read.

  The light guide 10 is not limited to the shape in which one surface is a mirror flat surface 13 and the other surface is a prism surface as described above. It is also conceivable to increase the direction scattering property so that a linear light having a high illuminance and a uniform illuminance distribution is irradiated onto the image surface of the document to be read.

  8 and FIG. 9 are specific examples thereof, in which FIG. 8 shows that one surface of the light guide 10 is a first prism surface 16 having a plurality of specular inclined surfaces 14 and the other surface is A plurality of triangular prisms or circular arcs (FIG. 8 triangular prisms) prism cuts 17a are arranged side by side in the short direction of light guide 10 (the direction connecting light incident surface 11 and light emitting surface 12). The prism surface 17 is used.

  Thereby, the light emitted from the LED light source is guided through the light guide 10 and reflected by the mirror inclined surface 14 of the first prism surface 16, and the reflected light is emitted from the second prism surface 17 to the gap. Refracted in the longitudinal direction of the light guide 10. For this reason, diffused light traveling in the longitudinal direction is irradiated from the gap of the document reading apparatus, and the illuminance distribution in the longitudinal direction is made uniform.

  In FIG. 9, it is assumed that one surface of the light guide 10 is a first prism surface 16 having a plurality of specular inclined surfaces 14, and the other surface is a plurality of triangular prisms or circular arcs (FIG. 9 is triangular prisms). ) Prism cut 17a is the second prism surface 17 arranged in parallel in the short direction of the light guide 10 (the direction connecting the light incident surface 11 and the light emitting surface 12), and at the same time, the light emitting surface 12 A plurality of triangular prisms or circular arcs (FIG. 9 triangular prisms) prism cuts 18 a are used as the third prism surface 18 arranged in parallel in the thickness direction of the light guide 10.

  Thereby, the light emitted from the LED light source is guided through the light guide 10 and reflected by the mirror inclined surface 14 of the first prism surface 16, and the reflected light is emitted from the second prism surface 17 to the gap. Refracted in the longitudinal direction of the light guide 10. At the same time, the light is emitted from the LED light source, enters the light guide 10, and is directly reflected by the third prism surface 18 (light emitting surface 12) without being reflected in the light guide 10 in the thickness direction of the light guide 10. Is refracted in the longitudinal direction of the light guide 10 when it exits from the prism surface 18 into the atmosphere.

  Therefore, the diffused light directed in the longitudinal direction is irradiated from both the gap of the light source device for reading the document and the light emitting surface 12 of the light guide 10, and the illuminance distribution in the longitudinal direction is further uniformized.

  If the light exit surface of the light guide is not a prism surface, light diffusing means such as applying light diffusion processing such as embossing or blasting to the light exit surface or providing a light diffusion sheet on the light exit surface Accordingly, it is possible to make the illuminance distribution uniform by using diffused light as irradiation light emitted from the light emitting surface of the light guide to the atmosphere.

    FIG. 10 is an explanatory view showing a reduction optical system of a general scanner in the case where the original reading light source device is used.

  A document reading light source device 1 and a first mirror 50 are accommodated below the contact glass 46, and are arranged so as to be movable along the contact glass 46. A second carriage 56, which accommodates the third mirror 52 and is movably disposed in conjunction with the first carriage 55, a condenser lens 60, a line CCD linear sensor 61, and a signal processing unit 62 are provided. Is provided.

  Then, the light emitted from the document reading light source device 1 accommodated in the first carriage 55 moving along the contact glass 46 is an image surface 47 of the document 45 to be read placed on the contact glass 46. Are transmitted through the contact glass 46 and scanned, and the original image by the reflected light is sequentially reflected by the first mirror 50, the second mirror 51, and the third mirror 52 to reach the condenser lens 60, A reduced image of the original image condensed by the condenser lens 60 is formed on the imaging surface of the line CCD linear sensor 61. Then, the CCD data (original image data) output from the line CCD linear sensor 61 is sent to the signal processing unit 62, subjected to image processing, and output to an external device.

  By using the document reading light source device of the present invention that irradiates the image light surface of the document to be scanned with linear light having a high luminance and a uniform illuminance distribution, the original image on the image surface can be accurately obtained. Can be read.

  Further, the document reading light source device of the present invention has a simple structure for irradiating linear light with high illuminance and uniform illuminance distribution, and thus can be reduced in size and cost. This contributes to the reduction in size and cost of an original reading apparatus such as a scanner incorporating the original reading light source device.

DESCRIPTION OF SYMBOLS 1 ... Document reading light source device 2 ... Board | substrate 5 ... LED light source 6 ... LED element 7 ... Sealing resin 8 ... Light emission surface 10 ... Light guide 11 ... Light incident surface 12 ... Light emission surface 13 ... Mirror surface flat surface 14 ... Mirror surface inclined surface 15 ... Prism surface 16 ... First prism surface 17 ... Second prism surface 17a ... Prism cut 18 ... Third prism surface 18a ... Prism cut 20 ... Reflective member 21 ... Specular reflection surface 30 ... Lamp house 31 ... Recessed part 32 ... Inner side surface 33 ... Open end 40 ... Air gap 45 ... Document to be read 46 ... Contact glass 47 ... Image plane 50 ... First mirror 51 ... Second mirror 52 ... Third mirror 55 ... First Carriage 56 ... Second carriage 60 ... Condensing lens 61 ... Line CCD linear sensor 62 ... Signal processor

Claims (4)

A long flat light guide,
A plurality of LED light sources arranged at a predetermined interval along one end surface along the longitudinal direction of the light guide and with the irradiation direction facing the end surface;
The light guide rises toward the end face at a predetermined angle with respect to the central axis along the short direction of the light guide on one surface of the flat plate and extends along the longitudinal direction of the light guide A plurality of inclined mirror surfaces extending in parallel are arranged in parallel, and a prism cut surface in which a plurality of triangular prisms or circular arc prisms are arranged in parallel in the lateral direction of the light guide is formed on the other flat surface. ,
An original reading light source device, wherein a specular reflection surface is disposed in parallel with an extending direction of the prism cut surface at a position facing the prism cut surface with a gap having a predetermined width. A long flat light guide,
A plurality of LED light sources arranged at a predetermined interval along one end surface along the longitudinal direction of the light guide and with the irradiation direction facing the end surface;
The light guide rises toward the end face at a predetermined angle with respect to the central axis along the short direction of the light guide on one surface of the flat plate and extends along the longitudinal direction of the light guide A plurality of inclined mirror surfaces extending in parallel are arranged in parallel, and a prism cut surface in which a plurality of triangular prisms or circular arc prisms are arranged in parallel in the lateral direction of the light guide is formed on the other flat surface. ,
A specular reflection surface is disposed in parallel with the extending direction of the prism cut surface at a position facing the prism cut surface with a gap having a predetermined width.
A document reading, wherein a plurality of triangular prisms or arc column prism cuts are arranged in parallel in the thickness direction of the light guide on an end surface opposite to an end surface on which the plurality of LED light sources are arranged. Light source device. Among the plurality of mirror-surface inclined surfaces, the mirror-surface inclined surfaces adjacent to each other have the same rising inclination angle with respect to the central axis along the short direction of the light guide, or the mirror-surface inclined surfaces located on the LED light source side. document reading light source device according to claim 1 or claim 2, wherein the inclination angle is small. The light guide is made of a transparent resin, and the rising inclination angle of the mirror inclined surface with respect to the central axis along the short direction of the light guide is in the range of 24 ° to 25 °. The document reading light source device according to claim 3 .

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