JP2016048875A - Linear light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear light source device which includes two light sources emitting lights of a different wavelength range at both ends of a light guide body and is capable of obtaining light distribution shaped approximately symmetrical to the longitudinal center of the light guide body in each light source.SOLUTION: The linear light source device includes two light sources emitting the lights of the different wavelength range at both ends of the light guide body. A first prism part comprising a prism element including a transmission surface transmitting the light from a first light source and a reflection surface reflecting the light from a second light source, among a plurality of prism elements formed between adjacent recessed grooves by forming a plurality of recessed grooves in a longitudinal direction side by side in the outer peripheral surface of the light guide body is provided on the side of the first light source. A second prism part comprising the prism element including the transmission surface transmitting the light from the second light source and the reflection surface reflecting the light from the first light source is provided on the side of the second light source.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a linear light source device for a document reading device used in devices such as a facsimile, a copying machine, and a scanner.

  2. Description of the Related Art Conventionally, for example, facsimile machines, copiers, scanners and the like are equipped with a document reading device that includes a light source device that illuminates the document surface and reads character information and image information on the document surface by reflected light from the document surface. ing.

  As a light source device for an original reading device, for example, an LED light source provided with an LED element is disposed at least one end of a rod-shaped light guide made of a translucent resin or the like, and light emitted from the LED light source Can be applied in the longitudinal direction of the light guide to irradiate the document surface. For example, Patent Document 1 discloses a linear light source device in which LED light sources are disposed at both ends of a rod-shaped light guide.

On the other hand, in recent years, development of a linear light source device that includes both a light source that emits ultraviolet light and a light source that emits infrared light is progressing without being limited to using a light source that emits visible light. .
For example, Patent Document 2 discloses a linear light source device that uses an LED element that emits visible light as a first light source and an LED chip that emits infrared light as a second light source. According to this linear light source device, it is possible to improve the accuracy of authenticity determination such as image reading accuracy and banknote identification.

JP 2011-151440 A JP 2007-164385 A

In the linear light source device disclosed in Patent Document 1, the light distribution in the longitudinal direction of the light guide is obtained by combining light from one LED light source and light from the other LED light source. It is.
On the other hand, in a linear light source device that is used by selectively turning on one of two light sources that emit light in different wavelength ranges, it is necessary to design the light distribution distribution related to each light source to be substantially the same. . Specifically, it is necessary to design the light distribution in the longitudinal direction of the light guide so that it is symmetrical with respect to the central position in the longitudinal direction. For example, in the apparatus disclosed in Patent Document 2, two light guides corresponding to the respective light sources are mounted. However, such a configuration has a problem of increasing the number of parts and increasing the size of the apparatus.

  The present invention has been made based on the above circumstances, and an object thereof is a linear light source device including two light sources that emit light in different wavelength ranges on both end faces of a light guide. Thus, it is an object of the present invention to provide a linear light source device capable of obtaining a light distribution having a substantially symmetrical shape with respect to the longitudinal center of the light guide for each light source.

The linear light source device of the present invention is opposed to each of a rod-shaped light guide having a reflecting portion and a light emitting portion formed along the longitudinal direction so as to face each other, and both end faces in the longitudinal direction of the light guide. And a second light source that emits light in a wavelength region different from that of the first light source, and the reflective portion of the light guide has a plurality of concave grooves on the outer peripheral surface. In a linear light source device formed by a plurality of prism elements formed between adjacent concave grooves by being formed side by side in the longitudinal direction,
Of the plurality of prism elements, a first prism comprising a plurality of prism elements each having a transmission surface that transmits light from the first light source and a reflection surface that reflects light from the second light source. A portion is provided on the first light source side from the longitudinal center,
Of the plurality of prism elements, a second prism composed of a plurality of prism elements each having a transmission surface that transmits light from the second light source and a reflection surface that reflects light from the first light source. The portion is provided on the second light source side from the center in the longitudinal direction.

  In the linear light source device according to the present invention, it is preferable that the pitch of the concave grooves increases toward the center in the longitudinal direction.

  In the linear light source device of the present invention, it is preferable that the inclination angle of the reflecting surface in the adjacent prism element with respect to the longitudinal direction becomes smaller toward the center in the longitudinal direction.

The linear light source device of the present invention reflects the light from the light source on the proximal side and the light from the light source on the distal side to the side of each light source from the longitudinal center in the reflection part of the light guide. Prism portions each including a prism element having a reflecting surface are provided. Thereby, in each prism element, the light from the proximal light source is transmitted and the light from the distal light source is actively reflected. As a result, even if the light guide has a configuration including two light sources that emit light in different wavelength ranges at both ends, when these are switched and turned on, each light source is guided. A light distribution having a substantially symmetrical shape with respect to the center in the longitudinal direction of the light body can be obtained.
Furthermore, by using a common light guide for guiding light emitted from each light source, the apparatus can be reduced in size.

(A), (b) is sectional drawing which shows the outline of the structure in an example of the linear light source device of this invention, (c) is an expanded sectional view which shows the outline of the structure of the reflection part in a light guide. It is sectional drawing perpendicular | vertical to the longitudinal direction of a light guide of the linear light source device shown in FIG. It is a figure which shows the light distribution curve of the linear light source device produced in Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail.

FIGS. 1A and 1B are cross-sectional views showing an outline of the configuration of an example of the linear light source device of the present invention, and FIG. 1C is an enlarged cross-sectional view showing an outline of the configuration of the reflecting portion in the light guide. is there. 2 is a cross-sectional view of the linear light source device shown in FIG. 1 perpendicular to the longitudinal direction of the light guide.
This linear light source device includes a rod-shaped light guide 10 in which both end faces 10a and 10b in the longitudinal direction are light-receiving surfaces, and a first light source 10 disposed opposite to one end face 10a of the light guide 10. 1 light source 30 a, a second light source 30 b disposed to face the other end surface 10 b of the light guide 10, and a light guide support base 40 for supporting the light guide 10.

The first light source 30a is a flat substrate 31a disposed opposite to the one end surface 10a of the light guide 10 in the longitudinal direction, and a first light emitting element mounted on one surface of the substrate 31a. The LED element 32a and the reflector 33a provided so as to surround the space between the one end face 10a of the light guide 10 and the LED element 32a.
The second light source 30b includes a flat substrate 31b disposed opposite to the other end surface 10b of the light guide 10 in the longitudinal direction and a second light emitting element mounted on one surface of the substrate 31b. The LED element 32b and the reflector 33b provided so as to surround the space between the other end face 10b of the light guide 10 and the LED element 32b.

  The light guide 10 is a substantially cylindrical rod-like body, and an emission portion 11 having an arc-shaped light emission surface is formed along the longitudinal direction, and a reflection portion is formed on a circumferential surface facing the light emission surface. 15 is formed along the longitudinal direction. The light guide 10 is supported and fixed by the light guide support base 40 disposed so as to extend along the light guide 10 in a state in which the emitting portion 11 faces a predetermined direction.

As a material constituting the light guide 10, for example, a light-transmitting material such as quartz glass, acrylic resin, polycarbonate resin, cycloolefin copolymer (COC), and cycloolefin polymer (COP) is used. When using what emits ultraviolet light as the 1st light source 30a or the 2nd light source 30b, it is preferable to use what consists of quartz glass as the light guide 10. FIG.
Moreover, as a material which comprises the light guide support stand 40, the light radiate | emitted outside the light guide 10 from places other than the output part 11 of the light guide 10 can be absorbed and shielded. For example, a polycarbonate resin or the like can be used. Moreover, what applied the coating which has a light absorptivity to the surface of a suitable base material can also be used.

  The reflecting portion 15 of the light guide 10 is formed with a plurality of prism elements formed between adjacent grooves by forming the plurality of grooves on the outer peripheral surface of the light guide 10 at positions spaced apart from each other in the longitudinal direction. 20. In this example, the concave groove is constituted by, for example, a V-shaped groove 16 having a substantially V-shaped cross section, and each prism element 20 has a trapezoidal cross section or a triangular cross section.

And in said linear light source device, the permeation | transmission surface 21 which permeate | transmits the light from the light source of a proximal side, and the distal to each side of light source 30a, 30b from the longitudinal direction center in the reflection part 15 of the light guide 10 Prism portions 27 and 28 each including a prism element 20 including a reflection surface 22 that reflects light from the light source on the side are provided.
Specifically, among the plurality of prism elements 20, a plurality of prism elements 20 including a transmission surface 21 that transmits light from the first light source 30a and a reflection surface 22 that reflects light from the second light source 30b. The 1st prism part 27 comprised from these is provided in the 1st light source 30a side from the longitudinal direction center. Of the plurality of prism elements 20, the prism element 20 includes a plurality of prism elements 20 each having a transmission surface 21 that transmits light from the second light source 30b and a reflection surface 22 that reflects light from the first light source 30a. The second prism portion 28 is provided on the second light source 30b side from the center in the longitudinal direction.

  The pitch of the V-shaped grooves 16 for forming the plurality of prism elements 20 constituting the prism portions 27 and 28 is preferably increased from the end of the light guide 10 toward the center in the longitudinal direction.

Further, the depth of the V-shaped groove 16 for forming the plurality of prism elements 20 constituting the prism portions 27 and 28 is determined based on the wavelength range of the light from each of the light sources 30a and 30b. It is preferable that the size is such that the light from the light source on the distal side can be totally reflected according to the refractive index. Therefore, the depth of the V-shaped groove 16 is asymmetric with respect to the longitudinal center of the light guide 10.
The depth of the V-shaped groove 16 is, for example, in the range of 0.05 to 0.2 mm.

In the present invention, the transmission surface 21 facing the light source on the proximal side preferably has an inclination angle α (see FIG. 1C) with respect to the longitudinal direction in the range of (90 ° −θ) to 90 °. . However, (theta) is the critical angle of the light ray which injects into the air from the light guide 10. FIG.
The critical angle θ of the light beam incident on the air from the light guide 10 is expressed by the following formula (1).
Formula (1): Critical angle θ = arcsin (1 / n)
[In said Formula (1), n is the refractive index of the light guide 10 with respect to the light of arbitrary wavelength ranges. ]
Specifically, when quartz glass is used as the light guide 10, the inclination angle α with respect to the longitudinal direction of the transmission surface 21 is preferably, for example, 80 to 90 °.

In the present invention, the reflecting surface 22 facing the light source on the distal side has an inclination angle β (see FIG. 1C) with respect to the longitudinal direction so that the light from the light source on the distal side is totally reflected. It is.
Specifically, when quartz glass is used as the light guide 10, the inclination angle β with respect to the longitudinal direction of the reflecting surface 22 is preferably 5 to 15 °, for example.

  In the adjacent prism element 20, it is preferable that the inclination angle β with respect to the longitudinal direction of the reflecting surface 22 facing the light source on the distal side becomes smaller toward the central side in the longitudinal direction.

In this linear light source device, the light from the LED element 32a of the first light source 30a is reflected directly or by the reflector 33a as shown in FIG. Is incident on one end face 10a. The light incident on the one end face 10 a of the light guide 10 is guided in the longitudinal direction by the light guide 10. At this time, the light incident on the transmission surface 21 of the prism element 20 constituting the first prism portion 27 located at one end side from the center position is transmitted through the prism element 20 to the outside of the light guide 10. It is emitted and diffused by the light guide support base 40. Further, the light incident on the prism element 20 constituting the second prism portion 28 located on the other end side from the center position is reflected by the reflecting surface 22 of the prism element 20, and the reflected light is guided to the light guide. The light is emitted from the light emission surface of the 10 emission portions 11.
On the other hand, the light from the LED element 32b of the second light source 30b is reflected directly or by the reflector 33b and enters the other end face 10b of the light guide 10 as shown in FIG. Light incident from the other end surface 10 b of the light guide 10 is guided in the longitudinal direction by the light guide 10. At this time, the light incident on the transmission surface 21 of the prism element 20 constituting the second prism portion 28 located on the other end side from the center position is transmitted through the prism element 20 to the outside of the light guide 10. And is diffused by the light guide support base 40. Further, the light incident on the prism element 20 constituting the first prism portion 27 located on the one end side from the center position is reflected by the reflecting surface 22 of the prism element 20, and the reflected light is guided by the light guide 10. The light is emitted from the light emission surface of the emission part 11.

As described above, according to the linear light source device having the above-described configuration, transmission from the light source on the proximal side is transmitted from the center in the longitudinal direction of the reflecting portion 15 of the light guide 10 toward the light sources 30a and 30b. Prism portions 27 and 28 each including a prism element 20 including a surface 21 and a reflection surface 22 that reflects light from a light source on the distal side are provided. Thereby, in each prism element 20, the light from the light source on the proximal side is transmitted and the light from the light source on the distal side is positively reflected. As a result, even if the two light sources 30a and 30b that emit light in different wavelength ranges are provided on the both end faces 10a and 10b of the single light guide 10, they are switched and turned on. For each of the light sources 30a and 30b, a light distribution having a substantially symmetrical shape with respect to the longitudinal center of the light guide 10 can be obtained.
Furthermore, by using a common light guide 10 that guides the light emitted from each of the light sources 30a and 30b, the apparatus can be reduced in size.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be added.

  Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

<Example 1>
With reference to the structure shown in FIGS. 1-2, the linear light source device which concerns on this invention which has the following specification was produced.
[Light guide support base (40)]
Material: Polycarbonate resin [Light source (30a, 30b)]
LED element (32a): emitting ultraviolet light with an emission wavelength of 365 nm LED element (32b): emitting infrared light with an emission wavelength of 950 nm [light guide (10)]
Dimensions: Full length 340 mm, outer diameter 5 mm, cylindrical material: quartz glass concave groove: V-shaped groove, gradually changing within 0.05 mm to 0.2 mm depth depending on longitudinal position of light guide, pitch 1 mm
Cross-sectional shape of prism element: trapezoidal or triangular shape, transmission surface inclination angle (α) in the range of 80 to 90 °, reflection surface inclination angle (β) in the range of 5 to 25 °

  In this linear light source device, the first light source (30a) is turned on alone, and the light guide (10) is arranged in the longitudinal direction at a position 12 mm away from the central axis of the light guide (10) in the vertical direction. When the light distribution was measured, a light distribution curve shown by a solid line (a) in FIG. 3 was obtained. Further, when the light distribution in the longitudinal direction of the light guide (10) when the second light source (30b) is lit alone is measured by the same method as described above, it is indicated by a broken line (b) in FIG. The light distribution distribution curve shown was obtained.

As is clear from the above results, according to the linear light source device according to the present invention, the light distribution distribution curves related to the first light source (30a) and the second light source (30b) are respectively light guides ( 10) It was confirmed that it has a substantially symmetrical shape with respect to the longitudinal center.
Further, the light distribution distribution curve obtained when the first light source (30a) is lit alone and the light distribution distribution curve obtained when the second light source (30b) is lit alone are substantially the same. It was confirmed to have a shape.

DESCRIPTION OF SYMBOLS 10 Light guide 10a One end surface 10b Other end surface 11 Output part 15 Reflection part 16 V-shaped groove 20 Prism element 21 Transmission surface 22 Reflection surface 27 First prism part 28 Second prism part 30a First light source 30b Second Light source 31a, 31b Substrate 32a, 32b LED element 33a, 33b Reflector 40 Light guide support base

Claims (3)

A rod-shaped light guide having a reflection portion and an emission portion formed along the longitudinal direction so as to face each other, a first light source disposed opposite to both end faces in the longitudinal direction of the light guide, and A second light source that emits light in a wavelength range different from that of the first light source, and the reflecting portion of the light guide is formed with a plurality of concave grooves arranged in the longitudinal direction on the outer peripheral surface. In the linear light source device constituted by a plurality of prism elements formed between adjacent concave grooves,
Of the plurality of prism elements, a first prism comprising a plurality of prism elements each having a transmission surface that transmits light from the first light source and a reflection surface that reflects light from the second light source. A portion is provided on the first light source side from the longitudinal center,
Of the plurality of prism elements, a second prism composed of a plurality of prism elements each having a transmission surface that transmits light from the second light source and a reflection surface that reflects light from the first light source. The linear light source device is characterized in that the portion is provided on the second light source side from the longitudinal center.   The linear light source device according to claim 1, wherein the pitch of the concave grooves increases toward the center in the longitudinal direction. 3. The linear light source device according to claim 1, wherein an inclination angle with respect to a longitudinal direction of a reflection surface in an adjacent prism element becomes smaller toward a central side in the longitudinal direction.

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