JPH0927255A - Reflection type photoelectric switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small switch having an enhanced light collecting effect and good detecting accuracy by arranging a light emitting element and a photodetector in such a way that one circles the other. SOLUTION: A light emitting element 3, such as a LED, is placed in the center of the bottom surface of a recess 26 in the end 25 of a base 2 in such a way that it is aligned with the optical axis C of a lens 5. A photodetector, 4 such as a photodiode, is placed in a circle around the element 3 in the recess 26 with a cylindrical light-blocking wall 27 located between. Therefore the optical axis of the lens 5 coincides with those of the elements 3, 4, resulting in the increase in the amount of reflected light impinging on the element 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective photoelectric switch.

[0002]

2. Description of the Related Art In recent years, some reflective photoelectric switches have a diameter as small as several mm.
An example of such a reflective photoelectric switch is shown in FIG. In FIG. 8, an LED (light emitting element) 101 and a PD (light receiving element) 101 are provided on a substrate 100 housed in a sleeve 106.
102 are provided. The light L emitted from the LED 101 passes through the lens 103 and is applied to the object W,
The reflected light L passes through the lens 103 and enters the PD 102.

In this prior art, the LED 101
The light L from the LED 10 is incident on the PD 102.
The emission direction of the light L from 1 is set obliquely with respect to the optical axis C of the lens 103. However, as indicated by the chain double-dashed line, when the distance to the object W changes, the amount of light incident on the PD 102 significantly decreases. That is, in this conventional technique, since the optical axes of the LED 101 and the PD 102 and the lens 103 do not coincide with each other, it is difficult to obtain the effect of focusing by the lens 103. Therefore, there are problems that the range of detectable distance is narrow, or the detection accuracy is poor.

On the other hand, in the optical fiber type shown in FIG. 9, since the light receiving fibers 105 are arranged concentrically with respect to the central light projecting fiber 104, the light is condensed by a lens (not shown). The effect is easy to obtain. However, the optical fiber has a problem that mechanical strength such as bending resistance and tensile strength is small, and that connection with a connector causes a cost increase or a decrease in light amount. Further, in the optical fiber, the clad 105a is provided around the fiber 105 and arranged in a dot shape of the light receiving fiber 105, so that it is inevitable that the light receiving area becomes small.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to improve the effect of light collection in a reflection type photoelectric switch (not an optical fiber type) provided with a light emitting / receiving element.

[0006]

To achieve the above object, according to the present invention, one of the light emitting and receiving elements is formed or arranged in an annular shape, and the other element is arranged in the center of the one element. It is characterized by being set up.

According to the present invention, since the light emitting and receiving elements are concentrically arranged, the light is condensed by making the optical axes of the lens and the light emitting and receiving element coincide with each other, and the reflected light is incident on the light receiving element. The amount of light can be increased.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are enlarged views of the first embodiment. First, the connection structure between the base 2 of the reflection type photoelectric switch and the coaxial cable 1 will be described. As shown in FIG. 1, a coaxial cable 1 concentric with one axis includes a shield wire (outer conductor) 11, a core wire (center conductor) 12, and a first coating material 13 that insulates between the two wires 11 and 12. It is composed of a second covering material 14 for covering the shielded wire 11. At the tip of the coaxial cable 1, the core wire 12 is exposed, and the shield wire 11 is exposed in a state of covering the first covering material 13. Further, between the two wires 11 and 12, the first covering is provided. The material 13 is exposed. Two coaxial cables 1 are fixed to the base 2 as described later.

The base 2 is a kind of so-called three-dimensional substrate, and has a long round bar shape as a whole and is made of an insulating material such as synthetic resin (for example, liquid crystal polymer). As shown in FIGS. 2B and 2C, the base 2 has a pair of U-shaped first, second and third grooves 21, 2 on the same axis.
2, 23 are formed along the longitudinal direction A of the base 2. The shielded wire 11, the core wire 12, and the first covering material 13 are stored in the first, second, and third grooves 21, 22, and 23, respectively, in a dropped state.

As shown in FIG. 2 (c), the inner surfaces of the first and second grooves 21 and 22 of FIG. 1, that is, the side surfaces of the base 2 which face each other, serve as terminal surfaces, respectively. 1
Lands 21a, 21b and second lands 22a, 2
2b is formed integrally with the base 2. In FIG. 1, the surfaces of the lands 21a and 22a are shaded.

As shown in FIG. 2B, the groove width of the first groove 21 is slightly wider than that of the shield wire 11, while the groove width of the second groove 22 is slightly wider than that of the core wire 12. . Therefore, the groove width of the second groove 22 is narrower than that of the first groove 21. The shield wire 11 is the land 21 of the first groove 21.
a and 21b are soldered (brazed) in a posture along the longitudinal direction A of the base 2, while the core wire 12 is attached to the second groove 2
The two lands 22a and 22b are soldered (brazed) in a posture along the longitudinal direction A of the base 2 and connected. The first groove 21, the third groove 23, and the second groove 22 are arranged in this order from the base end surface 24 of the base 2 to the tip portion 2.
It is formed toward 5.

Next, the essential part of the present invention will be described.
As shown in FIG. 3A, the tip portion 25 of the base 2 is
A recess 26 is formed. On the bottom surface of the recess 26, a light projecting element 3 such as an LED and a light receiving element 4 such as a PD are housed. As shown in FIG.
The light projecting element 3 is circular and is disposed in the center of the recess 26, and is disposed on the optical axis C of the lens 5 shown in FIG. On the other hand, the light receiving element 4 of FIG.
For example, it is formed in an annular shape such as a C shape, and is arranged concentrically with the light projecting element 3. A cylindrical light shielding wall 27 is formed around the light projecting element 3.

As shown in FIG. 3A, the base 2 is formed with first and second electric paths 31 and 32 for the light projecting element 3. The light projecting element 3 is connected and fixed to the second electric path 32 by soldering, and the second electric path 32 is electrically connected to the land 22a. On the other hand, the first electric circuit 31 and the light projecting element 3 are electrically connected by a wire (gold wire) 33, so that the light projecting element 3 is connected to the land 21a.
It is electrically connected to the shielded wire 11 via (FIG. 2B). The light projecting element 3 is connected through these electric lines 31, 32, etc.
Is supplied with electric power, and the light projecting element 3 emits light.

Further, as shown in FIG. 3B, the base 2 has third and fourth electric paths 41, 41 for the light receiving element 4.
42 are formed. The light receiving element 4 is connected and fixed to the fourth electric path 42 by soldering, and the electric path 42 is electrically connected to the land 22b. On the other hand, the third electric path 41 and the light receiving element 4 are electrically connected by the wire 43, and thereby the light receiving element 4 is electrically connected to the shield wire 11 via the land 21b. The light receiving element 4 photoelectrically converts the received light and outputs an electric signal to an amplifier (not shown) via the electric paths 41 and 42 and the coaxial cable 1.

These electric lines 31, 32, 41, 42 and the lands 21a, 21b, 22a, 22b of FIG. 2 (c).
Is formed by electroless plating, electroplating, or the like. The base 2 is molded by injection molding once or plural times as required. In addition, land 21
The a, 21b, 22a and 22b may be formed by inserting thin metal plates by insert. In addition, on the outer periphery of the base 2,
A cylindrical protective sleeve (housing) not shown is mounted.

In the reflection type photoelectric switch having the above structure, as shown in FIG. 2A, the light receiving element 4 has an annular shape, and the light projecting element 3 is arranged in the center of the light receiving element 4. The optical element 3 and the light receiving element 4 are arranged concentrically on the same optical axis C of the lens 5 of FIG. Therefore, even if the distance to the object changes, the reflected light is incident on the light receiving element 4, so that the effect of focusing is improved.

Further, in this embodiment, since the light receiving element 4 is formed in an annular shape, the area ratio of the light receiving element 4 to the outer diameter of the reflection type photoelectric switch is larger than that of arranging the two elements 3 and 4 in parallel. Can be set. Also, one lens 5 may be provided. Therefore, the reflection type photoelectric switch can be downsized without deteriorating the detection accuracy of the reflection type photoelectric switch.

Further, since the reflection type photoelectric switch is provided with the light emitting / receiving elements 3 and 4 and is not of the optical fiber type, it can be wired by an electric wire cable, so that the mechanical strength is improved and the cost is reduced. The advantages of wire cables are obtained.

Further, in this embodiment, the light receiving element 4 is formed in an annular shape and has a single continuous shape. Therefore, the light receiving area becomes larger than that in which the tip end surfaces of the optical fibers are arranged in a circle, and the light collecting efficiency is improved.

By the way, in the present specification, the term "annular" means
In addition to the C-shape of FIG. 2 (a), the complete ring of FIG. 4 (a),
An arrangement of two semi-annular rings as shown in FIG.
As shown in (c), it does not limit the shape of each element 4 alone, including those in which a plurality of rectangular light receiving elements 4 are arranged. Further, the elements formed or arranged in a ring shape are shown in FIG.
As shown in FIGS. 4A and 4A, one continuous element may be used, or as shown in FIGS. 4B and 4C, a plurality of divided elements may be used. In this specification, the circular shape includes not only a perfect circle as shown in FIG. 4B but also a shape close to a circle as shown in FIG. 4A.
Further, the light projecting element 3 may have a rectangular shape as shown in FIG.

The arrangement of the light projecting element 3 and the light receiving element 4
The shapes may be interchanged. That is, the light projecting element 3 may be formed in an annular shape, and the light receiving element 4 may be arranged in the center thereof. However, when the light projecting element 3 is annular, the spot of light is annular and large, so that the detection accuracy is generally better when the circular light projecting element 3 is disposed in the center.

By the way, in this embodiment, the recess 26 is formed in the base 2 of FIG. 3, and the lens 5 is directly attached to the base 2.
Since the lens 103 is fixed or fixed and attached, unlike the case where the lens 103 is fixed to the sleeve 106 as in the conventional example of FIG. 8, a deviation of the optical axis may occur between the elements 3 and 4 and the lens 5 of FIG. Nor.

Further, in this embodiment, both elements 3, 3 are attached to the tip portion 25 in the longitudinal direction A of the long rod-shaped base 2 of FIG. 2B.
4 is provided, and the conductors 11 and 12 of the coaxial cable 1 are arranged in a posture along the longitudinal direction A of the base 2 to form the lands 21a and 21
Since the b, 22a, and 22b are soldered, the entire reflection type photoelectric switch can be formed in an elongated shape. Therefore, since the outer diameter of the reflection type photoelectric switch can be reduced, the reflection type photoelectric switch can be arranged in a narrow space.

FIG. 5 shows an essential part of the second embodiment. In FIG. 5, the base 2 has a base portion 28 and a distal end portion 25 which are separate bodies, and an engaging projection 25 a of the distal end portion 25 is fitted into an engaging groove 28 a of the base portion 28 by resin elasticity. . The light projecting element 3 is fixed to the front end surface 28b of the base portion 28, while
The tip portion 25 has a flat surface 25 different from the tip surface 28b.
The light receiving element 4 is fixed on b. The tip portion 25 forms a cylindrical light shielding wall 27 and prevents light from the light projecting element 3 from directly entering the light receiving element 4. In addition to the light projecting element 3, a cavity 26a for fixing the wire 33 is formed in the tip portion 25, whereby the area of the light projecting element 3 and the light receiving element 4 can be increased. In addition, in FIG. 5, the electric circuit is omitted.

By the way, in each of the above embodiments, the base 2
However, in the present invention, part or all of the base 2 may be formed in a long flat plate shape in the present invention, as shown in FIG. 6 or 7. Further, the cable to be soldered (brazed) to the base 2 does not have to be a coaxial cable, and may be a normal cable having two parallel conductors. In this case, as shown in FIG. 6, the lands 21a, 22a, and
21b and 22b are arranged in parallel.

Further, in the embodiments of FIGS. 1 to 6, the longitudinal direction A of the base 2 and the emission direction of light coincide with each other, but in the present invention, as shown in FIG. The emission directions may be orthogonal.

[0027]

As described above, according to the present invention,
Among the light emitting and receiving elements, one element is formed or arranged in a ring shape and the other element is arranged in the center of the ring shape element, so that both elements are arranged concentrically on the optical axis of the lens. The light effect is improved, and the size of the device can be increased without increasing the size of the reflective photoelectric switch. Therefore,
It is possible to provide a small-sized reflective photoelectric switch with high detection accuracy. Further, since the present reflection type photoelectric switch is not of the optical fiber type, it is possible to use an electric wire cable having a higher mechanical strength and a lower cost than the optical fiber.

Further, according to the invention of claim 7, since the lens is provided in the recess of the base, the lens can be easily positioned with respect to the light emitting / receiving element, so that the optical axes of the lens and the light emitting / receiving element do not easily deviate.

According to the invention of claim 8, both elements are provided at the longitudinal end of a long rod-shaped or plate-shaped base, and the conductor of the cable is placed in a posture along the longitudinal direction of the base. Since it is brazed to, the entire reflection type photoelectric switch can be formed in an elongated shape. Therefore, the diameter of the reflective photoelectric switch can be reduced.

[Brief description of drawings]

FIG. 1 is an exploded enlarged perspective view of a reflective photoelectric switch with a partial cross section showing a first embodiment of the present invention.

FIG. 2A is a front view of a reflective photoelectric switch, and FIG.
Is a side view and (c) is a bottom view.

FIG. 3 is an enlarged cross-sectional view showing an electric path of a light emitting / receiving element.

FIG. 4 is an enlarged plan view showing another shape and arrangement of the light emitting / receiving element.

FIG. 5 is an enlarged cross-sectional view showing a second embodiment.

FIG. 6 is an enlarged view showing a third embodiment.

FIG. 7 is an enlarged cross-sectional view showing a fourth embodiment.

FIG. 8 is a vertical sectional view showing a conventional reflective photoelectric switch.

FIG. 9 is a front view showing an optical fiber type reflective switch.

[Explanation of symbols]

 1: Cable 11, 12: Conductor 2: Base 21a, 22a, 21b, 22b: Land (terminal surface) 25: Tip part 26: Recessed part 3: Light emitting element 4: Light receiving element 31, 32, 41, 42: Electric path 5: Lens C: Optical axis

Claims (8)

[Claims] 1. A reflection type photoelectric switch comprising a light projecting element for emitting light and a light receiving element for photoelectrically converting the received light in a single housing, wherein one of the light projecting and receiving elements has a ring shape. A reflection type photoelectric switch characterized in that the other element is formed or arranged and the other element is arranged in the center of one element. 2. The reflection type photoelectric switch according to claim 1, wherein a lens is disposed in front of both the elements, and the other element in the center is disposed on the optical axis of the lens. 3. The reflection type photoelectric switch according to claim 2, wherein the one element is a light receiving element and the other element is a light projecting element. 4. The reflective photoelectric switch according to claim 2, wherein the one element is formed in an annular shape and the other element is formed in a circular shape. 5. The reflection type photoelectric switch according to claim 2, wherein the one element is formed by one continuous element. 6. The device according to claim 2, wherein the one element is
A reflective photoelectric switch that is divided into multiple parts. 7. The device according to claim 2, wherein the both elements are provided on a base in which an electric path is formed in an insulator, and a recess for accommodating the both elements is formed in the base, and the recess is provided in the recess. A reflective photoelectric switch in which the lens is fixed or fixed. 8. The device according to claim 2, wherein the both elements are provided on a base having an electric path formed in an insulator, and the base is formed in a long rod shape or a plate shape, and the both elements are longitudinal ends of the base. And a pair of terminal surfaces are provided on the two side surfaces of the base, and conductors of the cable are brazed to the terminal surfaces in a posture along the longitudinal direction of the base. Reflective photoelectric switch.