JP2009025132A - Transmission type light area sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission type light area sensor that eliminates a part not irradiated with light near the end face of a sensor head at a light transmission side and can also detect an object to be detected at any position in an inspection area. <P>SOLUTION: A light transmission side sensor head includes a light-emitting guide body 12 for allowing light generated from a light-emitting element 13 to enter one end face for guiding light and to exit the other end face. A light reception side sensor head includes a light-receiving guide body 15 that allows light transmitted through the inspection area to enter one end face for guiding light and to exit the other end face for guiding to a photodetector 16. The sensor heads at the light emission and reception sides are positioned opposingly. The light-emitting guide body 12 is a sheet-like light guide body in a laminar structure consisting of a core material and at least a layer of sheath material for covering the core material and the periphery of the core material. The light-receiving guide body 15 is a sheet-like guide body in a laminar structure comprising a core material at least a layer of sheath material for covering the core material and the periphery of the core material and includes a plurality of optical fibers arranged so that the sectional shape becomes linear on an end face where light enters. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transmissive optical area sensor, and more particularly to a transmissive optical area sensor that irradiates an inspection region having a certain width from one sensor head and receives light passing through the inspection region by the other sensor head.

Some transmissive optical area sensors are formed by forming a sensor head using an optical fiber. In this sensor head, the end portions of a plurality of optical fibers are fixed to the sensor head main body, and the end portions of the optical fibers are arranged in one or a plurality of rows over the entire inspection region width. In the optical fiber area sensor configured as described above, light is irradiated from one sensor head so as to cover the inspection area width, and the light passing through the inspection area is received by the other sensor head. As an example in which the sensor head is formed by arranging the optical fiber end portions in one row, the one described in Japanese Patent Application Laid-Open No. 60-157125 (Patent Document 1) can be cited.
JP-A-60-157125

  However, since the optical fiber has a certain opening angle, the light emitted from the end face of the optical fiber of the sensor head has a spread. Therefore, as shown in FIG. 4, in the light emitted from the emission end face of the optical fiber 41 of the light emission side sensor head, a light non-irradiation part is generated in the vicinity of the light emission side sensor head end face. When the detected object 42 passes through a part other than the non-irradiated part, the light receiving level is lowered in the light receiving side area sensor, and the presence of the detected object 42 can be detected. When the light passes through the non-light-irradiated portion, the light receiving level is not sufficiently lowered in the light receiving side area sensor, and there is a problem that the presence of the detected object 42 is missed.

  Accordingly, an object of the present invention is to provide a transmissive optical area sensor that can detect an object to be detected at any position in an inspection region by eliminating a non-irradiated portion near the end face of the light emitting side sensor head. is there.

According to the present invention, the above object is achieved as follows:
A transmissive optical area sensor that irradiates light from a light emitting side sensor head to an inspection region having a width, and receives light passing through the inspection region by a light receiving side sensor head,
The light emitting side sensor head is configured to include a light guide for emission that guides light emitted from the light emitting element to enter one end face and emits the light from the other end face,
The light receiving side sensor head is configured to include a light receiving light guide that guides the light that has passed through the inspection region to be incident on one end face and guide the light to the light detecting element.
The light-emitting side sensor head and the light-receiving side sensor head are located in a facing relationship,
The emission light guide is a sheet-shaped light guide having a layer structure including a core material and at least one sheath material covering the periphery of the core material,
Is provided.

  In one aspect of the present invention, the light receiving light guide is a sheet-like light guide having a layer structure including a core material and at least one sheath material covering the periphery of the core material. In one aspect of the present invention, the light receiving light guide includes a plurality of optical fibers arranged so that a cross-sectional shape thereof is linear on the one end surface.

  According to the transmissive optical area sensor of the present invention, it is possible to detect an object to be detected at any position in the inspection region by eliminating the non-irradiated portion near the light emitting side sensor head end face.

  Hereinafter, embodiments of a transmissive optical area sensor of the present invention will be described with reference to the drawings.

  FIG. 1a is a schematic diagram showing the configuration of the first embodiment of the transmissive optical area sensor of the present invention. In the transmissive optical area sensor of the present embodiment, the light emitting side sensor head includes a head body 11 and a light guide 12 for emission. One end of the emission light guide 12 is fixedly held by the light emitting side sensor head main body 11. An end face of one end portion of the light guide 12 for emission is a light emission end face and is exposed to the outside at the end face of the light emitting side sensor head main body 11. The light exit end face of the exit light guide 12 may be as it is, or a transparent glass plate or a resin molded plate such as acrylic may be attached to protect the end face, and the light is collected. A lens or the like may be attached.

  The end face of the other end of the light guide 12 for emission is a light incident end face, and the light emitting element 13 is disposed so as to be adjacent to and face the light incident end face. The light emitted from the light emitting element 13 enters the light incident end face of the emission light guide 12, is guided in the emission light guide, and is emitted from the light emission end face of the emission light guide 12.

  The light receiving side sensor head includes a head main body 14 and a light receiving light guide 15. One end of the light receiving light guide 15 is fixedly held by the light receiving side sensor head main body 14. One end face of the light receiving light guide 15 is a light incident end face and is exposed to the outside at the end face of the light receiving side sensor head main body 14. The light incident end face of the light receiving light guide 15 may be as it is, or a transparent glass plate or a resin molded plate such as acrylic may be attached to protect the end face, and the light is collected. A lens or the like may be attached.

  The end face of the other end of the light receiving light guide 15 is a light emitting end face, and the light detecting element 16 is disposed so as to be adjacent to and face the light emitting end face. The light incident on the light incident end face of the light receiving light guide 15 is guided through the light receiving light guide, emitted from the light emitting end face of the light receiving light guide 15, and guided to the light detection element 16.

  The light emitting side sensor head and the light receiving side sensor head are arranged to face each other. As a result, the light emitted from the light emitting end face of the light guide 12 for light emission on the light emitting side sensor head is irradiated onto the inspection area having the required width (the vertical dimension in FIG. 1a), and the light that has passed through the inspection area is emitted. The light can be received efficiently by being incident on the light incident end face of the light receiving light guide 15 of the light receiving side sensor head.

  The sheet-like light guide used as the light guide 12 for emission and the light guide 15 for light reception will be described with reference to FIG. The sheet-like light guide 12 is composed of a core material 12a and a sheath material 12b, and the core material 12a is covered with the sheath material 12b. In such a layer structure of the sheet-like light guide 12, the sheath material may be composed of two or more layers.

  As the core material 12a, a known material can be used as the light guide core material, and for example, a methyl methacrylate homopolymer (PMMA) or copolymer can be used as a main component. Among them, it is preferable to configure PMMA as a main component because it is excellent in light transmittance and durability and is inexpensive. In addition, when using the copolymer of methyl methacrylate, it is preferable that content of methyl methacrylate shall be 50 mass% or more. Further, when a polycarbonate resin is used, the refractive index is higher than that of PMMA, the numerical aperture is increased, the amount of received light can be increased, and light leakage can be suppressed low when the sheet is bent. Furthermore, when the heat resistance is required, the above-mentioned polycarbonate resin or alicyclic polyolefin resin can be used.

  As the sheath material 12b, a known material can be used as the light guide sheath material. For example, the sheath material 12b can be formed of a resin composition containing a fluorine-containing olefin resin as a main component. Examples of the fluorinated olefin resin include a vinylidene fluoride copolymer, and specifically, a binary copolymer of vinylidene fluoride and tetrafluoroethylene, vinylidene fluoride and hexafluoroacetone, and the like. And a binary copolymer of vinylidene fluoride and trifluoroethylene, a terpolymer of vinylidene fluoride, tetrafluoroethylene and hexafluoroethylene, and the like.

  The sheet-shaped light guide 12 preferably has flexibility from the viewpoint of improving its handleability. For this purpose, the thickness (t) is suitably in the range of 0.2 mm to 3 mm. The width (W) may be arbitrarily selected according to the width of the inspection area. Further, the ratio W / t between the width (W) and the thickness (t) is suitably in the range of 10 to 10,000.

  A coating may be provided to protect the sheet-like light guide 12. A known material can be used as the covering material, and examples thereof include polyethylene resins, vinyl chloride resins, chlorinated polyethylene resins, and nylon resins.

  In the case where a sheet-like light guide is used as the light-receiving light guide 15, the width (W) thereof should be less than or equal to the dimension of the light detection element 16 (the dimension corresponding to the width direction of the sheet-like light guide). Is preferred. For example, the light receiving surface size of the photodiode S2551 manufactured by Hamamatsu Photonics Co., Ltd. is preferably 29.1 × 1.2 mm, and the width of the sheet light guide is preferably 29.1 mm or less.

  As the light emitting element 13, a known light emitting element can be used, and examples thereof include a halogen lamp, a metal halide lamp, a xenon lamp, a light emitting diode (LED), and a semiconductor laser (LD). Among the light-emitting elements described above, the LED is particularly preferable as the light-emitting element 13 of the present invention because the temperature rise around the LED is small even when it is lit for a long time, the size is small, and the size can be easily reduced. When an LED is used as the light emitting element 13, there is no limitation on the color (wavelength), and an LED having any wavelength such as white, red, green, and blue may be used. One LED may be installed adjacent to the light incident end face of the light guide 12 for emission, or a plurality of LEDs may be installed.

  As the light detection element 16, a known light detection element can be used, and examples thereof include a photodiode (PD) and a phototransistor.

  FIG. 2 is a schematic diagram showing a part of the configuration of the second embodiment of the transmission type area sensor of the present invention. This embodiment is the same as the first embodiment, except that a light receiving light guide 25 of the light receiving side sensor head is made of a plurality of optical fibers. One end of the light receiving light guide 25 is fixedly held by the light receiving side sensor head main body 24. An end face of one end of the light receiving light guide 25 is a light incident end face and is exposed to the outside at the end face of the light receiving side sensor head main body 24. At the end face of the one end of the light receiving light guide 25, the plurality of optical fibers constituting the light receiving light guide have a cross-sectional shape that is linear (a straight shape extending in the width direction of the inspection region). Are lined up. The other end face of the light receiving light guide 25 is a light emitting end face, and the plurality of optical fibers are converged on the light emitting end face.

  As the optical fiber constituting the light receiving light guide 25, an optical fiber having a known composition can be used. For example, an optical fiber manufactured by Mitsubishi Rayon Co., Ltd., having a fiber diameter of 2.0 mm, CK-80 CK-60 with fiber diameter φ1.5 mm, CK-40 with fiber diameter φ1.0 mm, CK-30 with fiber diameter φ0.75 mm, CK-20 with fiber diameter φ0.5 mm, and the like.

  According to the transmissive optical area sensor of the embodiment of the present invention as described above, it is possible to eliminate the light non-irradiation portion in all the inspection areas including the vicinity of the sensor end face, and the object to be detected at any position in the inspection area Can also be detected satisfactorily.

  Examples of the present invention will be described below.

Example 1
A transmissive optical area sensor belonging to the second embodiment as shown in FIG. 3A was produced.

  Width using PMMA (manufactured by Mitsubishi Rayon Co., Ltd., Acrypet) as the core material and vinylidene fluoride resin VP-100 (manufactured by Daikin Industries, Ltd.) as the sheath material as the light guide 31a for emission. A sheet-like light guide having a thickness of 30 mm and a thickness of 1 mm was used.

  An optical fiber sheet using 30 optical fibers (manufactured by Mitsubishi Rayon Co., Ltd., CK-40) having a fiber diameter of 1 mm was used as the light receiving light guide 32a.

  As the light emitting element 33, a halogen lamp 100W (manufactured by Mitsubishi Rayon Co., Ltd., halogen lamp light source ELI-100G) was used.

  An optical power meter (manufactured by Anritsu Co., Ltd., OPTICAL POWER METER ML910A) was used as the light measuring device 34 as a light detecting element for measuring the amount of light emitted from the light receiving light guide 32a.

  A pin gauge of 0.5 mm was used as the object to be detected 35, the sheet-like light guide-pin gauge distance WD1 was 1 mm, and the sheet-like light guide-optical fiber sheet distance WD2 was 20 mm.

  The pin gauge position output was 6.35 [dB] against the average output 9.35 [dB] of the emitted light amount, and an output difference of 2.99 [dB] could be obtained.

  The measurement results are shown in Table 1 and FIG.

(Comparative example)
As the transmissive optical area sensor of the comparative example of Example 1, the one shown in FIG. An optical fiber sheet using 30 optical fibers (manufactured by Mitsubishi Rayon Co., Ltd., CK-40) having a fiber diameter of 1 mm was used as the emission light guide 31b and the light reception light guide 32b. Other configurations are the same as those of the first embodiment. The pin gauge was measured in front of the optical fiber of the light guide 31b for light emission and between adjacent optical fibers. In front of the optical fiber, the output of the pin gauge position was 6.56 [dB] with respect to the average output 8.75 [dB] of the emitted light amount, and an output difference of 2.19 [dB] was obtained. Between the adjacent optical fibers, the pin gauge position output was 7.81 [dB] with respect to the average output 8.69 [dB] of the emitted light quantity, and the output difference was only 0.88 [dB]. When an optical fiber sheet was used as the light emitting light guide, a difference of 1.31 [dB] was obtained depending on the passing position of the detected object.

  The measurement results are shown in Table 1 and FIGS.

(Example 2)
A transmissive optical area sensor belonging to the first embodiment as shown in FIG.

  As the light guide 31c for emission and the light guide 32c for light reception, PMMA (manufactured by Mitsubishi Rayon Co., Ltd., Acrypet) is used as the core material, and vinylidene fluoride resin VP-100 (Daikin Industries, Ltd.) as the sheath material. A sheet-like light guide having a width of 30 mm and a thickness of 1 mm was used.

  Measurement was performed in the same manner as in Example 1. As a result, it was possible to confirm the fluctuation in the amount of light when compared with and without the pin gauge.

It is a schematic diagram which shows the structure of 1st Embodiment of the transmissive | pervious optical area sensor of this invention. It is a figure which shows roughly the structure of the sheet-like light guide used with the transmissive | pervious optical area sensor of FIG. 1a. It is a schematic diagram which shows the structure of 2nd Embodiment of the transmissive | pervious optical area sensor of this invention. It is a figure which shows roughly the structure of the transmissive | pervious optical area sensor produced in Example 1 of this invention. It is a figure which shows roughly the structure of the transmissive | pervious optical area sensor produced by the comparative example of this invention. It is a figure which shows schematically the structure of the transmissive | pervious optical area sensor produced in Example 2 of this invention. It is a figure which shows background art roughly. It is a graph which shows the measurement result in Example 1 (output when a pin gauge is arrange | positioned to a sheet-like light guide). It is a graph which shows the measurement result (output when a pin gauge is arrange | positioned in front of an optical fiber) in a comparative example. It is a graph which shows the measurement result (output when a pin gauge is arrange | positioned between adjacent optical fibers) in a comparative example.

Explanation of symbols

11: Light emitting side sensor head main body 12: Emitting light guide 12a: Core material 12b: Sheath material 13: Light emitting element 14: Light receiving side sensor head main body 15: Light receiving light guide 16: Light detecting element 24: Light receiving side sensor Head body 25: Light guide 31a for light reception: Light guide for emission (sheet-shaped light guide)
31b: Output light guide (optical fiber sheet)
31c: Outgoing light guide (sheet-like light guide)
32a: Light guide for light reception (optical fiber sheet)
32b: Light guide for light reception (optical fiber sheet)
32c: Light guide for light reception (sheet-shaped light guide)
33: Light emitting element 34: Light measuring device 35: Object to be detected 41: Optical fiber 42: Object to be detected

Claims (3)

A transmissive optical area sensor that irradiates light from a light emitting side sensor head to an inspection region having a width, and receives light passing through the inspection region by a light receiving side sensor head,
The light emitting side sensor head is configured to include a light guide for emission that guides light emitted from the light emitting element to enter one end face and emits the light from the other end face,
The light receiving side sensor head is configured to include a light receiving light guide that guides the light that has passed through the inspection region to be incident on one end face and guide the light to the light detecting element.
The light-emitting side sensor head and the light-receiving side sensor head are located in a facing relationship,
The transmissive optical area sensor, wherein the light guide for emission is a sheet-shaped light guide having a layer structure including a core material and at least one sheath material covering the periphery of the core material. The light-receiving light guide is a sheet-like light guide having a layer structure including a core material and at least one sheath material covering the periphery of the core material. Transmissive optical area sensor. 2. The transmissive optical area sensor according to claim 1, wherein the light receiving light guide includes a plurality of optical fibers arranged so that a cross-sectional shape thereof is linear at the one end face. .

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