JP2003303976A - Photodetector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photodetector whose condensing efficiency is satisfactory, and whose sensitivity is high. <P>SOLUTION: A light guide plate 10 disposed at the incident side of the light- receiving face of a photodetector 20 is provided with a corresponding area A shaped, corresponding to the light-receiving face of the photodetector 20 and a peripheral region B in the periphery of the corresponding region A. The peripheral region B is provided with a light-introducing means 3, and the corresponding region A is provided with a light outputting means 2. Lights introduced from the light-introducing means 3 in the peripheral region B to the inside part of the transparent board 1 are condensed in the corresponding region A, and outputted to the outside so as to be made incident to the light-receiving face of the light-detecting part 20 by the light-outputting means 2. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving device in which the light receiving sensitivity of a light detecting section is improved by using a light guide. 2. Description of the Related Art Various light receiving elements are used to detect optical signals and operate optical sensors. As such a light receiving element, for example, a phototransistor or a photodiode is known. [0003] These light receiving elements are:
In general, it has a characteristic of low detection sensitivity to weak light. For this reason, in order to increase the detection sensitivity, there has been a problem that the signal processing using a high-accuracy amplifier is required in the light receiving circuit, which increases the cost. In addition, there is a limit in increasing sensitivity even if circuit processing is performed, and there is a problem that desired characteristics cannot be obtained. The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a light receiving device capable of improving the light detection sensitivity of the light detection section. The light receiving device of the present invention that achieves the above object is a light receiving device that collects received light and emits it to a light detecting section, and is formed of a transparent plate. On the light guide plate
A corresponding region having a shape corresponding to the light receiving surface of the light detection unit and a peripheral region around the corresponding region, a light introducing unit is provided in the peripheral region, and a light emitting unit is provided in the corresponding region, The light introduced into the transparent plate from the light introducing means in the peripheral area is collected in the corresponding area, and is emitted to the outside so as to enter the light receiving surface of the light detection unit by the light emitting means. It is characterized by. According to the present invention, the light guide plate arranged on the incident side of the light receiving surface of the light detecting portion is a transparent plate having a corresponding region having a shape corresponding to the light receiving surface of the light detecting portion and a peripheral region around it. The light introducing means is provided in the peripheral area, the light emitting means is provided in the corresponding area, and the light introduced into the transparent plate from the light introducing means in the peripheral area is provided in the corresponding area. The light is collected and emitted to the outside so as to be incident on the light receiving surface of the light detection unit. For this reason, even if the light receiving surface of the light detection unit is small, a larger amount of light can be obtained. Therefore, the detection sensitivity of the light detection unit can be improved, and highly accurate processing by the light receiving circuit is not necessary for the detected light. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical sensor using a light guide of the present invention directly irradiates a light detection unit by combining with a light guide plate having a light introduction surface larger than the light receiving surface of the light detection unit. More light than the emitted light is taken in and made incident on the light detection unit, and the amount of light received by the light detection unit is increased. Hereinafter, the light receiving device of the present invention will be described based on embodiments. With reference to FIG. 2, a light guide plate 10 used as a light receiving device in the present invention will be described. FIG.
(A) is the top view of the light-guide plate 10, FIG.2 (b) is the sectional drawing. The light guide plate 10 is, for example, rectangular PE
It consists of a transparent plate 1 made of a transparent resin such as T, acrylic resin, polycarbonate or glass or made of glass. For example, the back surface of the center region A formed in a circular shape has a sandblasted surface (uneven surface, rough surface with surface average roughness Ra) Surface) 2. Further, the surface of the central region A is a smooth surface, and the surface (light receiving side) of the peripheral region B outside the central region A is
It is processed into a sandblasted surface (uneven surface, rough surface) 3 having a surface average roughness Ra. And the back surface of the peripheral region B is a smooth surface. Hereinafter, in this specification, the incident side is referred to as B.
The area and the emission side are displayed as area A. Here, the concavo-convex surface 3 is formed by bringing a mold into contact with a thermoplastic resin for thermal transfer or molding (such as injection molding or extrusion molding). Moreover, it is possible to employ various methods such as adding fine beads to a binder and applying them to the surface, or forming with a resist. The light guide plate 10 has such a structure, and light incident on the uneven surface 3 on the surface of the peripheral region B is scattered in the transparent plate 1 there. Most of the scattered light is incident on both surfaces of the transparent plate 1 at an angle greater than the critical angle determined by the difference between the refractive index of air and the refractive index of the transparent plate 1 and is totally reflected, and is reflected by multiple reflections in the transparent plate 1. It is converted into light guided to the optical part. Central area A
And the peripheral region B form a light guide. The guided light is guided to the central region A, and the light incident on the concave-convex surface 2 on the back surface is mostly scattered outside the transparent plate 1 and emitted. That is, light incident from the front surface side of the peripheral region B of the light guide plate 10 is taken into the light guide plate 10, collected through the light guide portion into the central region A, and emitted from the back surface of the central region A. . Further, most of the light that is directly incident from the front surface side of the central region A of the light guide plate 10 passes through the light guide plate 10 and is emitted from the back surface. Here, the light that is multiple-reflected in the transparent plate 1 and reaches the outer peripheral end face of the peripheral area B goes out and does not collect in the central area A. Therefore, the outer peripheral end face has A
A light reflecting layer 4 such as a light reflecting metal such as g, Al, Au, Pt, or Cu, or a white paint is applied, and the guided light incident on the outer peripheral end face is reflected to the opposite side to be effectively collected in the central region A. It is desirable to do so. The uneven surface 2 on the back surface of the central region A, the peripheral region B
As the surface average roughness Ra of the concavo-convex surface 3 of the surface,
It is preferable to select the range of 0.1 to 10,000 μm for efficiently introducing light, and it is more preferable to select the range of 1 to 1000 μm. Moreover, the range is 1-
The most preferable range is 100 μm. In place of the uneven surface 2 on the back surface of the central region A and the uneven surface 3 on the front surface in the peripheral region B, substantially concentric grooves, dents or protrusions may be provided. These are preferably arranged concentrically. As schematically shown in the cross-sectional view of FIG. 1, the light receiving device of the present invention faces the uneven surface 2 on the back surface of the central region A in the light guide plate 10 as described in FIG. A light detection unit 20 such as is arranged. In FIG. 1, light enters from the surface side of the light guide plate 10, and the light incident on the peripheral region B is scattered in the light guide plate 10 by the uneven surface 3, and is reflected multiple times in the light guide plate 10. Collected in the central area A. The light collected in this way is scattered and emitted from the uneven surface 2 on the back surface of the central region A, and enters the light receiving surface of the light detection unit 20. The direct light incident on the central area A of the light guide plate 10 passes through the light guide plate 10 and is similarly detected by the light detection unit 20.
Is incident on the light receiving surface. Therefore, the light incident on the light guide plate 10 having a larger area than the light detection unit 20 is collected by the light guide plate 10 and enters the light detection unit 20, which is more than when the light detection unit 20 is installed alone. A light amount of light enters the light detection unit 20. For this reason, the light receiving device using the light guide plate 10 of the present invention can efficiently condense even the weak light onto the light detection unit 20. That is, when the light detection unit 20 is used as an optical sensor, it is possible to accurately measure the light amount and the wavelength. Here, the outer shape of the light guide plate 10 is as follows:
Although not limited to a rectangle, a standardized rectangular shape or a hexagonal shape is desirable for more efficient power generation by installing a large number of light receiving devices without a dead space. The shape of the central region A of the light guide plate 10 is desirably matched to the shape of the light receiving surface of the light detection unit 20. Further, the light guide plate 10 of the light receiving device is deteriorated or deteriorated due to use over time, so that light cannot be collected efficiently, and the light collection efficiency is lowered.
In that case, it is desirable to remove the light guide plate 10 and replace it with a new one so that it can be returned to its original state. The light receiving device of the present invention uses the light guide plate 10 as described with reference to FIG. The size of this light guide plate is
It is determined appropriately according to what kind of processing is performed by the light detection unit 20. In order to collect weak light, the length of the light guide portion can be set to, for example, 1 m or more. When it is necessary to collect sunlight or the like over a wide area, the length of the light guide can be further increased. However, when the length of the light guide is too long, the attenuation of the light amount increases. For this reason, in this invention, the upper limit of the length of a light guide part is set to 200 m. That is, in the present invention, the length of the light guide is preferably selected from 1 m to 200 m. Moreover, it is desirable that the length of the light guide unit be 3 m or more and 100 m or less. Furthermore, it is desirable that the length of the light guide unit is 5 m or more and 20 m or less. 3 to 5 are front views showing other embodiments of the light guide plate used in the light receiving device of the present invention. The light guide plate 10a shown in FIG. 3 has two light emitting portions (A). As described above, by providing a plurality of light emitting portions on the light guide plate, the light detection portions 20a arranged at different positions for the light taken from the single light incident portion (B),
20b can be emitted. In the example of FIG. 3, the corresponding area A described in FIG. 1 is formed at both ends of the light guide plate 10a, and the peripheral area B is formed at the center. The light guide plate 10b shown in FIG. 4 has two light incident portions (B), but the light emitting portion (A) is formed at the same position as one of the light incident portions (B). Is.
In the configuration of FIG. 4, light is taken from the plurality of incident portions (B) into the light guide plate 10 b and guided as in the configuration of FIG. 1.
The light is emitted from a single light emitting part (A). For this reason, there exists an advantage which the light quantity condensed on the photon detection part 20 increases. The light guide 10c shown in FIG. 5 has two light incident portions (B). Moreover, it has two light emission parts (A). In this way, light taken from a plurality of incident portions is guided to the light guide, and a plurality of light emitting portions are provided to collect the increased amount of light in the light detection portions 20a and 20b arranged at different positions. Can be lighted. If a plurality of light emitting portions are provided as shown in FIGS. 3 and 5, when an optical sensor is disposed opposite to the plurality of light emitting portions, either one of the light sensors is normally used and the other is used. This optical sensor can be used for backup. For this reason, there exists an advantage that it can respond immediately when a regular optical sensor breaks. As described with reference to FIGS. 1 and 3 to 5, in the light guide applied to the light receiving device of the present invention, the number of light incident portions (B) and light emitting portions (A) can be set arbitrarily. Determined. Moreover, the installation positions of the light incident part (B) and the light emitting part (A) can be selected not only from the central part and the end part of the transparent plate but also from any position. For this reason, the optimal light-receiving device can be comprised according to the use and function of a photon detection part. FIG. 6 is an explanatory view showing another embodiment of the present invention. In this example, the light guide plate configured as shown in FIG.
It is used as a light collecting means. In FIG. 6, CCDs 21a to 21e are provided in the light detection unit 20x. Reference numerals 10p to 10t denote light guide plates having the configuration shown in FIG. 1, and each emitting portion B is opposed to the position of the CCD. In the configuration of FIG. 6, the light collected by the light guide plates 10p to 10t is emitted to the CCD, so that the operation sensitivity of the CCD can be improved. Although the light receiving device of the present invention has been described based on the embodiments, the present invention is not limited to these embodiments, and various modifications are possible. The central area A from which the light guide light is emitted does not necessarily have to be located at the center of the light guide plate 10 and may be shifted from the center or at the end. However, if the area A is located substantially at the center, the transmission efficiency can be increased. The light receiving device of the present invention described above can be configured as follows, for example. (1) A light receiving device that collects received light and emits the light to a light detection unit, and a light guide plate formed of a transparent plate has a corresponding region having a shape corresponding to the light receiving surface of the light detection unit and its periphery The peripheral area is provided with light introducing means, the corresponding area is provided with light emitting means, and the light introduced from the peripheral area light introducing means into the transparent plate is The light receiving device, which is collected in the corresponding area and emitted to the outside so as to be incident on a light receiving surface of the light detection unit by the light emitting means. (2) The light receiving device according to (1), wherein the light introducing means is provided on the front surface side of the transparent plate and the light emitting means is provided on the back surface side of the transparent plate. (3) The light-receiving device as described in (1) or (2) above, wherein the light introducing means and the light emitting means comprise an uneven surface provided on the surface of the transparent plate. (4) The light-receiving device as described in (3) above, wherein the surface roughness Ra of the irregular surface is in the range of 0.1 to 10,000 μm. (5) The light receiving device according to any one of (1) to (4), wherein a light reflecting layer is provided on an outer peripheral end face of the peripheral region of the transparent plate. (6) The light receiving device according to any one of (1) to (5), wherein the light guide plate is replaceable. As is apparent from the above description, in the light receiving device of the present invention, the light guide plate arranged on the incident side of the light receiving surface of the light detecting portion corresponds to the light receiving surface of the light detecting portion. It is formed of a transparent plate having a corresponding region of shape and a peripheral region around it, and a light introducing means is provided in the peripheral region, and a light emitting means is provided in the corresponding region. The light introduced from the light introducing means into the transparent plate is collected in the corresponding region, and is emitted to the outside so as to be incident on the light receiving surface of the light detection unit by the light emitting means. For this reason, even if the light receiving surface of the light detection unit is small, more light can be obtained. Therefore, the detection sensitivity of the light detection unit can be improved,
High-precision processing by the light receiving circuit is not necessary for the detected light.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view schematically showing a configuration of a light receiving device according to an embodiment of the present invention. FIG. 2 is a plan view (a) and a sectional view (b) of an example of a light guide plate used in the present invention. FIG. 3 is a front view showing another embodiment of the present invention. FIG. 4 is a front view showing another embodiment of the present invention. FIG. 5 is a front view showing another embodiment of the present invention. FIG. 6 is an explanatory diagram showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Transparent plate 2, 3 ... Uneven surface (sandblasted surface, rough surface) 4 ... Light reflection layer 10, 10a-10c, 10p-10t ... Light guide plate 20, 20a, 20b, 20x ... Light detection Sections 21a to 21e ... CCD A ... central region B ... peripheral region

Claims (1)

What is claimed is: 1. A light receiving device that collects received light and emits the light to a light detection unit, wherein the light guide plate formed of a transparent plate corresponds to a light receiving surface of the light detection unit. A corresponding region having a shape to be formed and a peripheral region around the corresponding region, wherein the peripheral region is provided with light introducing means, and the corresponding region is provided with light emitting means, and is transparent from the light introducing means in the peripheral region. The light introduced into the plate is collected in the corresponding region, and is emitted to the outside so as to be incident on the light receiving surface of the light detection unit by the light emitting means.