JP5716156B2 - Linear light source device using point light source and illumination device for optical reader using the same - Google Patents

Description

  The present invention relates to a linear light source device, and more specifically, a linear light source device that uses a highly directional point light source as a light source, and converts the point light from the point light source into linear light, and the linear light source device. The present invention relates to an illumination device for an optical reader.

  In recent years, research and development of light-emitting diodes (hereinafter referred to as “LEDs”) have rapidly progressed, and various types of LEDs have been developed and commercialized and used in a wide range of fields. It ’s coming. In the field of illumination, in addition to uses replacing fluorescent lamps and light bulbs, they are also used for light sources of image sensors in optical readers, for example.

  However, compared with fluorescent lamps and halogen lamps, LEDs have a strong directivity of light, and if they are simply arranged, the light amount distribution in the light irradiation portion varies and it is difficult to read an image. For this reason, various ideas have been made in order to make the light amount distribution in the light irradiated portion uniform.

  For example, Patent Document 1 below describes an invention of an image reading apparatus and an image forming apparatus. In the invention of this image reading apparatus, a plurality of LEDs are arranged along the main scanning direction, and a diffusion member for diffusing the light from the LEDs with a uniform light quantity distribution in the main scanning direction is provided between the LEDs and the original glass plate. I have. An image sensor used in this image reading apparatus will be described with reference to FIG. The light emitted from the LED 22 passes through the convex lens-shaped diffusing portion 24a of the diffusing member 24, and is once converged, then diffused, irradiates the original D, becomes reflected light, and is received by the slit. The Thus, even if the LED 22 diverges and emits less light, the light is diffused by the diffusing unit 24a, so that the document can be irradiated with a uniform light amount distribution.

  Patent Document 2 below describes an invention of a linear light source unit. The invention of this linear light source unit has a translucent resin rod provided with a reflecting mirror on one end surface, and a high-refractive-index diffuse reflector attached to the outer peripheral surface of the translucent resin rod in the form of straight strips in the axial direction. It is comprised by the formed diffusion stripe and the light source provided integrally with the rod at the other end surface of the translucent resin rod. As the distance from the light source increases, the amount of light decreases. Therefore, in order to make the luminance of the light irradiation surface uniform, diffusion fringes are provided on the resin rod. As shown in FIG. 9, the width of the diffusion stripe 61 provided in the linear light source device 6 becomes wider as the distance from the light source 62 increases. By using the present invention, the number of point light sources used in the linear light source device can be reduced and energy saving can be achieved.

JP 2008-271158 A Japanese Utility Model Publication No. 6-21940

  However, since the number of LEDs used in the light source device described in Patent Document 1 is large, the amount of heat generation is large, and it is difficult to reduce the weight, and it is difficult to increase the reading speed. Further, in the linear light source unit as described in Patent Document 2, since the LED is attached to the end, the length of the resin rod depends on the LED power, that is, if the LED power is low, the length is short. Only the distance could be illuminated.

  In view of the above problems, the present inventor arranges a plurality of point light sources at regular intervals and at equal intervals, and converts the light from each point light source into a linear light source, thereby obtaining uniform linear illumination light. In addition, we have developed a linear light source device that can handle linear illuminations of various lengths.

  Accordingly, an object of the present invention is to provide a lightweight linear light source device that uses a highly directional point light source and can convert light from the point light source into a linear light source without sealing the LED with a resin or the like. The purpose is to provide.

In order to achieve the above object, a linear light source device of the present invention includes a point light source, a bottom portion having a long side and a short side, in which a hole for installing the point light source is formed, and the bottom portion. A long side surface portion having a predetermined length standing vertically from a long side and a short side surface portion having a predetermined length standing vertically from the short side of the bottom surface portion A linear light source device having a casing and a light conducting reflector supported by the short side surface and the long side surface, wherein the light conducting reflector is centered on the optical axis of the point light source. The central reflection light guide unit and a plate-like body provided with an outer reflection light guide unit around the central reflection light guide unit are provided so as to extend outward from the side surfaces of the long sides. a pair of a light irradiation direction regulating unit, other light irradiation mounted in parallel at a said light irradiation direction regulating portion and the predetermined width A direction adjusting portion, and having a.

  In the linear light source device of the present invention, a plurality of rectangular holes whose lengths of sides parallel to the short sides are unchanged are formed in the outward reflecting portion.

  In the linear light source device of the present invention, the point light source is a light emitting diode or a laser diode.

  In the linear light source device of the present invention, the long side surface portion of the housing has an arc shape.

  In the linear light source device of the present invention, the casing, the light conducting reflection plate, and the light irradiation direction adjusting portion are formed of an ultrafine foamed light reflecting member.

  In the linear light source device of the present invention, a diffusion sheet or a diffusion plate for diffusing light is attached to the opening portion of the light irradiation direction adjusting unit.

  In the linear light source device of the present invention, the light irradiation direction adjusting portion and the housing are integrally formed.

  Furthermore, in order to achieve the above object, a linear illumination device used in the optical reading device of the present invention includes the linear light source device according to any one of the above, a mounting table, and a condensing device, and the line The reflector is provided so that the light irradiated from the planar light source device and reflected by the mounting table is condensed to the condensing device.

  According to the linear light source device of the present invention, the light from the point light source that has been converted into a uniform linear light source by the light-conducting reflector is applied to the line of uniform brightness with a desired thickness by the light irradiation direction adjusting unit. It is possible to illuminate a desired direction.

  If the angle of the point light source with respect to the optical axis is smaller than 45 degrees, the reflected light from the point light source is converged at the connecting portion between the side wall portion and the irradiation direction adjusting portion, and the light use efficiency is reduced. . Further, if the angle of the point light source with respect to the optical axis is larger than 60 degrees, the height of the linear light source device becomes high and the installation range of the linear light source device has to be widened.

  By making the shape of the light conduction reflection hole a rectangular hole whose length parallel to the short side is unchanged, the longitudinal direction of the illumination range and the direction of the light interference fringes formed by the light conduction reflection hole can be obtained. Since they are orthogonal to each other, it is difficult for shadows of the holes provided in the light conducting reflection plate to appear, and uniform illumination light is easily obtained. Moreover, the ratio of an opening part can be raised compared with a round hole.

  Both light-emitting diodes and laser diodes are well-known point light sources with high directivity and high emission intensity. Therefore, according to the linear light source device of the present invention, a bright linear light source device can be obtained even if the size is large.

  By making the light irradiation direction adjustment portion into a curved plate shape, the connection between the side surface portion and the light irradiation direction adjustment portion is smoothly connected, so that the reflected light from the point light source converges toward the connection portion. It is possible to increase the light utilization efficiency.

  By making the long side surface portion into an arc shape, not only linear illumination light but also curved illumination light can be provided.

  The ultrafine foamed light reflecting member can obtain more uniform scattered light in all directions as compared with, for example, a case where light scattering particles are dispersed in a plastic material. Therefore, according to the linear light source device of the present invention, illumination light with a more uniform illuminance distribution can be obtained. Furthermore, since the ultrafine foamed light reflecting member is lightweight, the weight of the linear light source device can be suppressed.

  By attaching a diffusion sheet or a diffusion plate, the illumination light can be made more uniform.

  According to the linear illumination device of the present invention, it is possible to obtain linear illumination light with uniform brightness, so that clearer optical reading can be performed.

1A is a perspective view of a linear light source device according to Embodiment 1 of the present invention, and FIG. 1B is a cross-sectional view taken along line IB-IB in FIG. 1A. It is a disassembled perspective view of the linear light source device which concerns on Example 1 of this invention. FIG. 3A is a plan view of a photoconductive reflector used in the linear light source device according to Embodiment 1 of the present invention, and FIG. 3B is a modification of the photoconductive reflector. 4A to 4F are cross-sectional views of a portion corresponding to FIG. 1B of the linear light source device of each modification. FIG. 5A is a perspective view of a linear light source device according to Embodiment 2 of the present invention, and FIG. 5B is a plan view of a light conducting reflector used in the linear light source device according to Embodiment 2 of the present invention. 6A is a perspective view of a linear light source device according to Embodiment 3 of the present invention, and FIG. 6B is a side view of the linear light source device according to Embodiment 3 of the present invention. FIG. 7A is a plan view of an optical reading apparatus according to the fourth embodiment of the present invention, and FIG. 7B is a sectional view taken along line VIIB-VIIB in FIG. 7A. 1 is a cross-sectional view of an image reading device disclosed in Patent Document 1. FIG. It is a perspective view of the linear light source unit currently disclosed by patent document 2. FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the embodiments described below exemplify linear light source devices for embodying the technical idea of the present invention, and are not intended to specify the present invention. It is equally applicable to those of other embodiments within the scope.

  First, with reference to FIGS. 1-3, the linear light source device which concerns on Example 1 of this invention is demonstrated. 1A is a perspective view of a linear light source device according to Embodiment 1 of the present invention, FIG. 1B is a cross-sectional view taken along line IB-IB in FIG. 1A, and FIG. 2 is a linear shape according to Embodiment 1 of the present invention. 3A is an exploded perspective view of the light source device, FIG. 3A is a plan view of the light conducting reflector used in the linear light source device according to Embodiment 1 of the present invention, and FIG. 3B is a modification of the light conducting reflector.

  The linear light source device 1 used in the present embodiment includes a point light source 2 with strong directivity, a rectangular casing 3 to which the point light source 2 is attached, a light conducting reflection plate 4, and a light irradiation direction adjusting unit 5b. 5c. The point light source 2 uses an LED having one light emitting element or a plurality of light emitting elements.

  The casing 3 has a long side and a short side, and has a rectangular bottom surface portion 3a provided with a plurality of holes 30 for attaching the point light source 2, and stands vertically from the long side and the short side of the bottom surface portion 3a. The long side surface portions 3b and 3c and the short side surface portions 3d and 3e are provided, and an opening 3f is provided on the surface facing the bottom surface portion 3a. The opening 3f of the casing 3 is covered with the light conducting reflection plate 4, and the light conducting reflection plate 4 is fixed to the edge of the opening. The casing 3 and the light conducting reflecting plate 4 can be formed separately, and the light conducting reflecting plate 4 can be fixed to the opening edge of the casing 3. In addition, you may assemble with the casing 3 and the light conduction reflective plate 4 by cutting out the part corresponded to the casing 3 and the light conduction reflection plate 4 from one board body, and bending it.

  The bottom surface portion 3a has a rectangular shape with a long side of 10 cm and a short side of 2.5 cm, and holes 30 for attaching the point light sources 2 are provided at equal intervals on a line connecting the midpoints of the short sides. From the long side and the short side of the bottom surface portion 3a, long side surface portions 3b and 3c having a height of 3 cm and short side surface portions 3d and 3e having a height of 5 cm are vertically erected.

  As shown in FIG. 3A, the photoconductive reflector 4 is provided with a central photoconductive reflector 4a around the optical axis of the point light source 2 and an external photoconductive reflector 4b around the central photoconductive reflector 4a. Yes.

  The central light conducting / reflecting part 4a is formed to have a high light reflectance, reflects strong light emitted from the point light source 2, and the reflected light is reflected by the inner wall surface of the casing and the light conducting reflecting plate 4 in a multiple reflection manner. ing. The light reflectivity of the central light conducting / reflecting portion 4a is appropriately set by selecting an optical reflecting plate material and processing the material (eg, forming a half groove, adjusting the plate thickness), thereby efficiently using light. Will be able to.

  An outer light conducting / reflecting part 4b is provided on the outer periphery of the central light conducting / reflecting part 4a. The outer light conducting / reflecting portion 4b is provided with a hole 4c that increases as the distance from the point light source increases.

  As shown in FIG. 3B, the holes 4c are provided so as to be parallel to the long side and the short side of the light conducting reflection plate 4, and all the sides parallel to the short side direction have the same length. It is good also as the square holes 4c1-4cn by which the magnitude | size is adjusted by making only a parallel side different. By using such a square hole, a large opening area can be obtained, and a large amount of light from the point light source 2 can be used. In addition, the illuminance can be easily made uniform by changing only the side parallel to the long side direction.

  The light irradiation direction adjusting portions 5b and 5c have the same rectangular shape, and are attached to the upper portions of the long side surface portions 3b and 3c in a state of being inclined 45 degrees toward the point light source 2 symmetrically with respect to the optical axis of the point light source. ing. The lengths of the long sides of the light irradiation direction adjusting portions 5b and 5c are the same as those of the long side surface portions 3b and 3c, and a gap 5a having a constant width h is formed between the light irradiation direction adjusting portions 5b and 5c. Is provided. A uniform linear light source is obtained by irradiating the light passing through the light conducting reflection plate 4 from the gap h. In the present embodiment, the light irradiation direction adjusting units 5b and 5c are attached with an inclination of 45 degrees. However, by reducing this angle and reducing the width h of the gap 5a, it is possible to obtain a narrower uniform linear light source light. Further, the amount of light can be increased by increasing the angle and increasing the width h of the gap 5a. However, if the angle is too small, the angle of the connecting portion between the long side surface portions 4b and 4c and the light irradiation direction adjusting portions 5b and 5c becomes too acute, and the reflected light focused on the connecting portion increases, resulting in light loss. Becomes larger. In addition, if the angle is too large, the height of the linear light source device 1 itself is increased.

  The casing 3, the light conducting reflection plate 4, and the light direction adjusting portions 5b and 5c forming the linear light source device 1 are members having high reflectivity, for example, light reflectivity 98%, light transmittance 1%, and light absorption rate 1 % Of a material such as an ultrafine foamed light reflecting plate. Since this ultrafine foamed light reflecting material can reflect the light from the point light source 2 on the inner wall surface of the casing 3 with high light reflectance, it can be used efficiently. Further, since the ultrafine foamed light reflecting plate is lightweight, the weight of the linear light source device 1 can be suppressed. Furthermore, since the ultrafine foamed light reflecting plate is easily available and relatively inexpensive, the cost can be reduced even when the linear light source device 1 is manufactured.

  A modification of the linear light source device according to the first embodiment of the present invention will be described with reference to FIG. 4A to 4F are cross-sectional views of a portion corresponding to FIG. 1B of the linear light source device of each modification.

  As shown in FIG. 4A, a light irradiation direction adjusting unit 51b that is longer than the light irradiation direction adjusting unit 51c may be used. Further, as shown in FIG. 4B, the long side surface portion 3b is longer than the long side surface portion 3c, and the irradiation direction adjusting portions 52b and 52c are parallel to the bottom surface portion 3a. 3c may be attached. By setting it as the above structures, the irradiation direction of light can be changed from the optical axis of the point light source 2 to another direction.

  Further, as shown in FIGS. 4C and 4D, the light irradiation direction adjusting units 53b, 53c, and 53d may be attached so that light is irradiated in two directions. The light irradiation direction adjusting portions 53b and 53c are attached to the long side surface portions 3b and 3c, and the light irradiation direction adjusting portion 53d is attached in parallel to each of the light irradiation direction adjusting portions 53b and 53c with a certain width h. .

  In the above-described embodiment and modification, a flat plate is used as the light irradiation direction adjusting unit, but a curved plate obtained by cutting a part of a cylinder as shown in FIG. 4E may be used. By using the curved plate, the corner portion is eliminated, so that the reflected light does not converge toward the corner portion, the amount of light irradiated from the gap 5a increases, and the illuminance increases. Further, as shown in FIG. 4F, the point light source 2 may be attached to the long side surface portion 3b or 3c instead of the bottom surface portion 3a. Even if the location where the linear light source device 1 is installed is low and installation is difficult, the height of the linear light source device 1 can be reduced and installed by attaching the point light source 2 to the side surface of the long side. .

  With reference to FIG.5 and FIG.6, the linear light source device which concerns on Example 2 of this invention is demonstrated. 5A is a perspective view of the linear light source device according to the second embodiment of the present invention, and FIG. 5B is a plan view of a light conducting reflector used in the linear light source device according to the second embodiment of the present invention. 6A is a perspective view of a linear light source device according to Embodiment 3 of the present invention, and FIG. 6B is a side view of the linear light source device according to Embodiment 3 of the present invention.

  In the above embodiment, the shape of the long side surface portion is a flat rectangular shape. However, as shown in FIG. 5, the long side surface portion is shaped as an arc having a circle center on a plane parallel to the bottom surface portion. It is good also as a shape. As shown in FIG. 5, as the long side surface portions 31b and 31c have an arc shape, the bottom surface portion 31a and the light conducting reflection plate 41 also have an arc shape, and by connecting a plurality of the linear light source devices 1B, Instead of straight linear illumination light, so-called donut-shaped circular illumination light can be obtained. Further, as shown in FIG. 6, the shape of the long side surface portion may be an arc shape having a center of a circle on a plane parallel to the long side surface portion. By connecting a plurality of linear light source devices 1C each having an arc shape with a circle center on a surface parallel to the long side surfaces 32b and 32c in the longitudinal direction, linear illumination light can be obtained even on a curved surface. .

Next, an optical reading apparatus according to Embodiment 3 of the present invention will be described with reference to FIG. In addition,
FIG. 7A is a plan view of an optical reading apparatus according to the fourth embodiment of the present invention, and FIG. 7B is a sectional view taken along line VIIB-VIIB in FIG. 7A.

The image forming apparatus 6 includes an apparatus main body and an image reading device 7 provided on the apparatus main body. The image reading apparatus 7 may be incorporated in the apparatus main body.

  The image forming apparatus 6 includes an original glass table G on which an original is placed or an original is fed by an automatic original feeder (not shown), a linear light source device 1D for reading the original, and an image sensor. Guide shafts 61a and 61b for guiding in the sub-scanning direction are provided. For example, a document glass table G which is a document table through which light passes is partitioned by a stay S. The main scanning direction is the arrow A direction, and the sub-scanning direction is the arrow B direction.

  The linear light source device 1 </ b> D is connected to a belt 63 that circulates by a motor 62. The linear light source device 1D is normally detected by a sensor (not shown) and stands by at the home position.

  The linear light source device 1D is supported by one guide shaft 61a, is guided to move in the sub-scanning direction B, and is simply supported on the other guide shaft 61b. Therefore, the linear light source device 1D can smoothly reciprocate at a uniform speed in the sub-scanning direction B without being pinched with respect to the guide shafts 61a and 61b. For this reason, the image reading device 7 can read the document uniformly without unevenness.

  The operation of the image reading apparatus will be described. There are two types of document reading operations: flow reading and fixed reading. First, the flow reading will be described. In the flow reading, the original is moved and the linear light source device 1D is fixed to read the original.

  The automatic document feeder supplies the document on the document tray to the document discharge tray through the document glass table G. At this time, the linear light source device 1 </ b> D is moved and stopped under the original glass table G, and the original passing through the original glass table G is irradiated with the light of the LED 2 to read the original. The operation of reading the document will be described later. The document glass table G is a glass table that allows the linear light source device 1D to read the document through the document, and is therefore a document glass table for flow reading.

  Next, fixed reading will be described. In the fixed reading, the original is fixed and the linear light source device 1D is moved to read the original.

  The user opens the automatic document feeder and opens the original glass table G. Then, the user places a document on the document glass table G and closes the automatic document feeder. As a result, the document is pressed and brought into close contact with the document glass table G by the automatic document feeder. Thereafter, the linear light source device 1D reads the document by irradiating the document with the light of the LED 2 while moving in the sub-scanning direction B. The operation of reading the document will be described later. As described above, the document glass table G is a glass table on which a document is placed and which moves the linear light source device 1D to read the document.

  The document reading operation of the linear light source device 1D will be described. Regardless of whether it is flow reading or fixed reading, the original and the image sensor are moved relative to each other to read the original, and the reading operation itself of the linear light source device 1D is the same. Therefore, the reading operation of the linear light source device 1D in the fixed reading will be described.

  The LED 2 irradiates the document. In the linear light source device 1D, the respective reflected lights irradiated by the respective LEDs 2 arranged in the main scanning direction A in the main scanning direction A are condensed in the main scanning direction A by the condenser lens 71 and are electrically generated by a CCD (not shown). Converted to a signal.

  While reading the main scanning direction A, the linear light source device 1D moves under the original glass table G by a predetermined pitch in the sub-scanning direction B by guiding the guide shafts 61a and 61b and pulling the belt. Read. As described above, the linear light source device 1D moves while performing the reading operation in the main scanning direction A and the reading operation in the sub-scanning direction B, and uses the electric signal obtained thereby as the image signal as the image forming apparatus 6 main body. Send to. The apparatus main body copies the document on the sheet based on the image signal from the image reading apparatus 7.

  When this linear light source device is used in an optical reading device, linear illumination light with uniform luminance can be obtained, so that clearer optical reading can be performed. Further, when the linear light source device is formed of an ultrafine foamed light reflecting member, since it is lightweight, the reading speed can be increased, and the reading speed can be increased.

DESCRIPTION OF SYMBOLS 1 Linear light source device 2 Point light source 3 Casing 4 Light conduction reflective plate 5 Light irradiation direction adjustment part 6 Image forming apparatus 7 Image reader

Claims (8)

A point light source, a hole having a hole for installing the point light source, a bottom surface portion having a long side and a short side, and a length having a predetermined length erected vertically from the long side of the bottom surface portion A casing composed of a side surface portion, a short side surface portion having a predetermined length that is erected vertically from the short side of the bottom surface portion, and the short side surface portion and the long side surface portion. A linear light source device having a supported light conducting reflection plate,
The light conducting reflection plate is composed of a central reflection light guide portion centered on the optical axis of the point light source and a plate-like body provided with an outer reflection light guide portion around the central reflection light guide portion,
A pair of light irradiation direction adjusting portions provided to extend outward from the long side surface portions;
Other light irradiation direction adjusting units attached in parallel with a predetermined width from the light irradiation direction adjusting unit,
A linear light source device comprising:   2. The linear light source device according to claim 1, wherein a plurality of rectangular holes whose length of a side parallel to the short side is invariant are formed in the outward reflecting portion.   The linear light source device according to claim 1, wherein the point light source uses a light emitting diode or a laser diode.   The linear light source device according to claim 1, wherein the long side surface portion of the housing has an arc shape.   The linear light source device according to claim 1, wherein the casing, the light conducting reflection plate, and the light irradiation direction adjusting portion are formed of an ultrafine foamed light reflecting member.   The linear light source device according to claim 1, wherein a diffusion sheet or a diffusion plate for diffusing light is attached to an opening portion of the light irradiation direction adjusting unit.   The linear light source device according to claim 1, wherein the light irradiation direction adjusting portion and the housing are integrally formed. A linear light source device according to claim 1-7, the mounting table, and a condenser, the light reflected on the mounting table is irradiated from the linear light source device is condensed into the condenser unit A linear illumination device used in an optical reading device, characterized in that a reflector is provided.

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