JPS6235237Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an optical transmission device used in an optical fiber type photoelectric switch, etc., which uses an optical fiber and transmits and receives light between the ends of the optical fiber.

A fiber optic photoelectric switch uses an optical fiber to guide light so that it can perform light detection even in narrow spaces where even a small photoelectric switch cannot fit. Therefore, it is often used in narrow spaces by bending the tip of the optical fiber to determine the direction of the light. However, if the bending diameter is bent to a small value, light transmission loss may occur, so the bending diameter cannot be made very small, and eventually it cannot be applied to narrow spaces. Therefore, as shown in FIG. 1A, the optical fiber 1
It is conceivable to provide an inclined reflective surface 12 at the tip of the prism to convert the direction of the light as shown by the solid line, but light that is not parallel is transmitted without being reflected and is lost as shown by the dotted line. becomes. In order to prevent this loss, a reflecting plate 13 may be further attached to the reflecting surface 12 as shown in FIG. The disadvantage is that object detection becomes difficult.

In view of the above, an object of the present invention is to provide an optical transmission device equipped with a light projection direction converter that is easily and detachably attached to the tip of an optical fiber to simultaneously focus and change the direction of light. do.

An embodiment of the present invention applied to an optical fiber type photoelectric switch will be described below with reference to FIG. In FIG. 2, a light emitting direction converter 22 and a light receiving direction converter 32 are attached to the tips of the light emitting optical fiber 21 and the light receiving optical fiber 31, respectively. And these converters 2
2 and 32 have substantially the same structure, and are made of a rod-shaped light guide made of plastic or the like, and have recesses 23 and 33 at one end into which the tip of the optical fiber fits. Protrusions 24, 34 forming convex lenses are provided within the recesses 23, 33. At the other end, recesses 25 and 3 are provided with inclined reflective surfaces 26 and 36 forming prisms.
5 is provided. Each converter 22, 32 is detachably attached by inserting and fitting the tips of the optical fibers 21, 31 into the recesses 23, 33.

Even if the light from the projecting optical fiber 21 is emitted from the end and diffused, it is focused by the convex lens and becomes a parallel light beam, which travels through the light guide of the converter 22 and is reflected by the reflective surface 26 to change its direction. Projected. Therefore, the projected light is substantially parallel light rays, there is no diffusion of the light, and all the light is reflected by the reflecting surface 26, so there is little loss. The thus projected light enters the light-receiving direction converter 32, is reflected by the reflecting surface 36, is focused by a convex lens, and enters the tip of the light-receiving optical fiber 31. Similarly to the light emitting direction converter 22, this light receiving direction converter 32 can change the direction of light with less loss, and can prevent the light receiving direction from expanding.

In this way, converters 22 and 32 are installed on the light emitting side and the light receiving side.
As shown in FIG. 2, by attaching this, it is possible to easily perform optical detection within a narrow space sandwiched between walls 41 and 42.

As described above, according to the configuration of the embodiment, the direction of light can be changed with less light loss, and the light can be prevented from being diffused. Furthermore, the light projection direction converter has a simple structure and can be made by integral molding of synthetic resin, making it easy to manufacture and also easy to attach to or remove from the tip of the optical fiber.

Note that in the above embodiment, converters are installed on the light emitting side and the light receiving side, but it is possible to obtain sufficient effects by simply installing a converter on the light emitting side, so the direction of the light can be adjusted on the light receiving side. If it is not necessary to convert the light source, it is sufficient to install a converter only on the light emitting side.

In the optical transmission device of the present invention, a recess is provided at one end of the light projection direction converter made of a rod-shaped light guide so that the tip of the light projection optical fiber can be attached and detached, and a protrusion forming a convex lens is provided within the recess. It is characterized by having a reflective surface forming a prism at the other end. Since the protrusion forming the convex lens is provided near the tip of the light emitting optical fiber in this manner, a detection distance can be obtained with a small amount of light emitted. That is,
The light emitted from the tip of the optical fiber is diffused, so if it is not focused by a convex lens, then
The light incident on the optical fiber on the light receiving side is at a part of the output angle, and the amount of light received is reduced. In such a case, to increase the amount of light received, either increase the amount of light emitted or shorten the distance between the emitting optical fiber and the receiving optical fiber so that light from all emission angles enters the receiving optical fiber. However, increasing the amount of light emitted will increase the power consumption of the light emitting element and increase costs, and shortening the distance between the emitting and receiving optical fibers will reduce the distance required to change the direction of light emitting. This results in the inability to maintain sufficient distance for objects to pass.
In any case, this is a problem, but the optical transmission device of the present invention solves this problem and allows a long detection distance with a small amount of projected light.

[Brief explanation of the drawing]

1A and 1B are sectional views of a conventional example, and FIG. 2 is a side view of an embodiment of the present invention. 11, 21, 31...optical fiber, 12, 2
6, 36... Reflective surface, 13... Reflective plate, 22...
Light emitting direction converter, 32...Light receiving direction converter.

Claims (1)

[Scope of utility model registration request] In an optical transmission device having a light emitting optical fiber and a light receiving optical fiber, and transmitting and receiving light between the tips of these optical fibers, a light emitting direction converter is provided at the tip of the light emitting optical fiber. This light projection direction converter is formed of a rod-shaped light guide, and one end thereof is provided with a recess into which the tip of the light projection optical fiber is fitted, and a protrusion forming a convex lens is provided in the recess. What is claimed is: 1. An optical transmission device characterized in that a reflective surface forming a prism is provided at the other end.