JPH03211403A - Fluorescent fiber sensor - Google Patents

Abstract

PURPOSE:To accurately detect the number and size of bodies to be detected by arranging a fluorescent fiber in the passing area of the body to be detected and arranging light sources parallel to the fiber and a photodetector on the fiber end surface. CONSTITUTION:The fluorescent fiber 5 whose core 51 is made of resin containing fluorescent coloring matter is arranged in the passing area of the bodies 1 to be inspected which are mounted on a conveyor, etc. The light sources 6 which make parallel light beams incident on the fluorescent fiber 5 are arranged and the photodetector 7 which detects variation in the quantity of light pertaining to the intrusion of the bodies 1 to be detected is provided on the fiber end surface. When the bodies 1 to be detected enter the passing area to cut of K of N incident light beams, the photodetector 7 detects variation in the intensity of projection light and the number and size of the bodies 1 to be detected are detected from a specific arithmetic expression; and the detection accuracy is improved and the fiber is easily connected to a signal processing circuit.

Description

[Detailed Description of the Invention] [Summary] An optical sensor that detects objects mounted on a conveyor or other conveyance device, particularly a fluorescent fiber sensor that enables improved detection accuracy, to improve the detection accuracy of size and count value. With the aim of providing a low-cost optical sensor that can be easily connected to a signal processing circuit, etc., the fluorescent fiber consists of a core and a gland surrounding the outer periphery of the core, and the core is made of a resin containing a fluorescent dye. and a light source that is arranged parallel to the fluorescent fiber through the passage area of the detected object and makes a parallel beam of light enter the fluorescent fiber, and detects a change in the amount of light due to the penetration of the detected object into the passage area. A photodetector is arranged on the end face of the fluorescent fiber.

[Industrial application field]

The present invention relates to an optical sensor that detects an object mounted on a conveyor or other transport device, and particularly to a fluorescent fiber sensor that enables improved detection accuracy.

For example, in a manufacturing process, various products that are conveyed together on the same conveyor may be classified by product based on height and size using optical sensors provided along the way. Further, the number of products or parts that are irregularly placed over a wide area and transported may be counted by optical sensors provided along the way.

However, if the number of light-receiving elements is reduced in an optical sensor used for such applications, the spacing between the light-receiving elements becomes wider, and the detection accuracy of size and count value decreases. Although the detection accuracy is improved, there is a problem that the connection between the light receiving element and the signal processing circuit etc. becomes extremely complicated.

Therefore, there is a demand for an optical sensor that can improve the detection accuracy of size and count value without complicating the connection between the light receiving element and the signal processing circuit.

[Conventional technology]

FIG. 5 is a schematic diagram showing a conventional optical sensor.

In the figure, the conventional optical sensor has a plurality of light emitting elements 2 and a plurality of light receiving elements 3 facing each other through the passage area of the detected object 1, and the output signals of the plurality of light receiving elements 3 are sent to a signal processing circuit 4. It has been entered. For example, an optical sensor that detects the height of a detected object 1 has a plurality of light emitting elements 2 and a plurality of light receiving elements 3 arranged on both sides of an area through which the detected object 1 passes, as shown in FIG. 5(a). The light incident on the light receiving element 3 from the light emitting element 2 forms a parallel grid at equal intervals. That is, the approximate height of the detected object 1 can be detected based on how many lights are blocked by the detected object 1 that has entered the passage area.

In addition, as shown in FIG. 5(b), the optical sensor that counts the detected objects 1 that are irregularly placed and transported and the optical sensor that detects the planar size of the detected object I are A light-emitting element 2 and a plurality of light-receiving elements 3 are arranged one above the other, and light incident from the light-emitting element 2 to the light-receiving element 3 forms a parallel grid at equal intervals. That is, when the detected object 1 that is irregularly placed and transported blocks at least one beam of light, the detected object 1 has entered the passage area and is counted. Furthermore, the planar size of the detected object 1 can be detected based on how many lights are blocked by the detected object 1 that has entered the passage area.

[Issue 8 to be solved by the invention] However, in conventional optical sensors, when the number of light receiving elements is reduced,
As the spacing between the light receiving elements becomes wider, the detection accuracy of size and count value decreases.If the spacing between the light receiving elements becomes wider, the detection accuracy of size and count value improves, but the connection between the light receiving element and the signal processing circuit, etc. However, the problem was that it was extremely complicated and costly.

An object of the present invention is to provide a low-cost optical sensor that can improve the detection accuracy of size and count value, is easy to connect to a signal processing circuit, etc.

Means for Solving 1 Problem] FIG. 1 is a schematic diagram showing a fluorescent fiber sensor according to the present invention. The same objects are represented by the same symbols throughout the figures.

The above problem consists of a core 51 and a cladding 52 surrounding the outer periphery of the core 51, and the core 51 is parallel to the fluorescent fiber 5 through the passage area of the detected object 1. It has a light source 6 which is arranged at S and makes parallel light beams incident on the fluorescent fiber 5,
The photodetector 7 that detects a change in the amount of light due to the intrusion of the detected object 1 into the passage area is achieved by the fluorescent fiber sensor of the present invention, which is disposed on the end face of the fluorescent fiber 5.

[For production]

In Fig. 1, a core and a gland surrounding the outer periphery of 17 are arranged in parallel with the fluorescent fiber, the core of which is made of resin containing a fluorescent dye, and the fluorescent fiber through the passage area of the object to be detected. The fluorescent fiber of the present invention has a light source that makes parallel light rays enter the fiber, and a photodetector that detects a change in light amount due to the entry of an object to be detected into the passage area is disposed on the end face of the fluorescent fiber. In the sensor, the elements connected to the signal processing circuit etc. are I to 2.
With only one photodetector, there is no need to complicate the connection between the photodetector and the signal processing circuit, etc., and since the parallel light from the light source can be incident on any position of the fluorescent fiber, the size and count value can be reduced. It is possible to realize an optical sensor that can improve detection accuracy.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a cross-sectional view showing the structure of a fluorescent fiber, FIG. 3 is a diagram showing the propagation of light within the fluorescent fiber, and FIG. 4 is a section for explaining the principle of the fluorescent fiber sensor according to the present invention.

In FIG. 2, for example, a fluorescent fiber 5 is formed of a core 51 made of polycarbonate resin containing a fluorescent dye and a cladding 52 made of a fluorine resin surrounding the outer periphery of the core 51. 53
As shown in FIG. 3, absorbs light incident from the outside through the ground 52 and emits fluorescence. The fluorescent fiber has a refractive index n2 of the crand 52 compared to a refractive index n2 of the core 51.
Since the fluorescence is small, part of the fluorescence emitted by the fluorescent dye 53 is emitted to the outside from the side, but the remaining fluorescence is reflected at the interface between the core 51 and the cladding 52, and the fluorescence in the proportion calculated by the following formula is emitted from the core 51. Propagated internally.

X=1 nz/n+ The fluorescent fiber sensor according to the present invention has such a fluorescent fiber 5 and, for example, a plurality of light sources 6 arranged in parallel with the fluorescent fiber 5, as shown in the fourth part, and the fluorescent fiber is connected from the light source 6 to The light incident on 5 constitutes a parallel grid at equal intervals. For example, there is a strength ■ at a position Z distance away from the output end face.

, when light with a width W is incident, the intensity of the light emitted from the fiber end face I is
.

is determined by the following formula.

Assuming that the object to be detected 1 enters the passage area and the book is blocked among the N incident lights, the change in the intensity of the emitted light due to the intrusion of the object to be detected 1 is determined by the following equation.

That is, by disposing a photodetector on the end face of the fluorescent fiber 5 and detecting changes in the intensity of the emitted light, it is possible to detect the presence, size, etc. of the object to be detected entering the passage area.

Such a fluorescent fiber sensor requires only one or two photodetectors to be connected to a signal processing circuit, etc., without complicating the connection between the photodetector and the signal processing circuit, and moreover, it can detect parallel light from a light source. can be incident on any position of the fluorescent fiber, making it possible to closely space the light sources and improve the detection accuracy of size and count values.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to improve the detection accuracy of size and count value, and it is possible to provide a low-cost optical sensor that can be easily connected to a signal processing circuit or the like.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a fluorescent fiber sensor according to the present invention, Fig. 2 is a cross-sectional view showing the structure of the fluorescent fiber, Fig. 3 is a diagram showing the propagation of light within the fluorescent fiber, and Fig. 4 is a diagram showing the present invention. Figure 5 is a diagram explaining the principle of a fluorescent fiber sensor, which is a conventional optical sensor. In the figure, 1 represents an object to be detected, 6 represents a light source, 51 represents a core, and 53 represents a fluorescent dye. 5 is a fluorescent fiber, 7 is a photodetector, 52 is a cladding, FIG. 1 is a front view showing 41 of the fluorescent fiber. Ibar rj' If) Maru's propagation ε shown below Japanese map gona 2 books Sada Moe (: '26 Hall Fufuibasenbu's agency ε RBR
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Claims (1)

[Claims] A fluorescent fiber (5) consisting of a core (51) and a cladding (52) surrounding the outer periphery of the core (51), the core (51) being made of a resin containing a fluorescent dye, and an object to be detected (1). The fluorescent fiber (5
) and a light source (6) that is arranged parallel to the fluorescent fiber (5) and makes parallel light beams incident on the fluorescent fiber (5), and a light detection device that detects a change in the amount of light due to the entry of the object to be detected (1) into the passage area. A fluorescent fiber sensor characterized in that a container (7) is disposed on an end surface of the fluorescent fiber (5).