JPH0336883Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a laser receiver for position detection, and is particularly suitable for detecting the position of an object by detecting when a laser beam is interrupted by an object. Regarding laser receivers.

(Prior art) Conventionally, it has been known that the light from a lamp is optically shaped into a beam, the beam is received by an optical sensor, and the position of the object is detected by detecting that the beam is blocked by an object. ing.

However, with this method, when the beam length is increased, the beam diameter increases at a high rate, making it difficult to obtain positional accuracy.

Therefore, it has been proposed to use laser light instead of lamp light. In this case, even if the beam length is increased, the rate at which the beam diameter expands is small, and positional accuracy can be increased.

On the other hand, even if improvements have been made on the light beam side as described above, no corresponding improvements have been made on the light receiving side. In other words, we only have the same photo receiver as when we were unable to increase the beam length.

However, as we increase the beam length,
Since the influence of external light increases, it is conceivable that unless the defense function against external light is enhanced, it will not be possible to increase the beam length in practice, despite the efforts made on the light beam side.

(Purpose of the invention) The present invention was made in view of the above circumstances, and aims to improve the defense function of the photoreceptor against external light, and to be able to suitably cope with the case where the beam length is increased using laser light. The purpose is to

(Configuration to achieve the purpose) Thus, the position detection laser receiver of the present invention has the following features:
A light selective introduction means for selectively introducing light of the same wavelength as a laser beam, a light diffusion means for diffusing the light introduced by the light selective introduction means, and a diffused light of the laser beam introduced by the light selective introduction means. an external light sensor that primarily detects the diffused light of the external light introduced by the light selective introduction means; an output difference signal between the laser beam sensor and the external light sensor; and a difference signal output means.

(Function) The light selective introduction means first eliminates the influence of external light of a different wavelength by selectively introducing only the laser beam and external light of the same wavelength. This method focuses on the fact that laser light has a single wavelength.

The light diffusion means applies the influence of external light that has not been eliminated by the light selective introduction means evenly to the laser light sensor and the external light sensor, and by diffusing the external light, the laser light sensor and the external light This eliminates the difference in the position of the optical sensor. Since laser light is a beam with an extremely narrow diameter compared to external light, the rate of diffusion is small, and it is mainly detected by a laser beam sensor and only slightly detected by an external light sensor.

Therefore, by calculating the difference in the outputs of both sensors using the difference signal output means, the influence of external light can be canceled and only the information contained in the laser beam can be extracted.

(Embodiment) 1 shown in FIG. 1 is an embodiment of the laser receiver for position detection of the present invention, which includes an interference filter 2 as a light selective introduction means, a milky white translucent acrylic plate 3 as a light diffusion means, and a laser beam. It basically consists of a solar cell 4 as a sensor for external light, a solar cell 5 as a sensor for external light, and a differential amplifier 6 as a difference signal output means.

The laser beam L is, for example, a He-Ne laser beam with a diameter of about 0.3 to 3 mm, and the laser beam L is a beam of about 0.3 to 3 mm in diameter.
The beam is incident at a position directly above the beam.

The interference filter 2 transmits the wavelength of the laser beam, and the laser beam L is transmitted to the milky white semi-transparent acrylic plate 3.

The milky white semi-transparent acrylic plate 3 receives the laser beam L.
However, since the diameter of the laser beam L is small, most of the light remains in the upper part 7 of the solar cell 4.

The proportion of the upper part 7 in the field of view seen from the solar cell 4 is large, but the proportion of the upper part 7 in the field of view seen from the solar cell 5 is small. Therefore, it may be considered that the laser light is mainly detected by the solar cell 4.

On the other hand, out of the external light G, light having a wavelength different from that of the laser beam is excluded by the interference filter 2, and only the external light having the same wavelength is incident on the milky-white translucent acrylic plate 3. For example, the external light G is the light of an illumination light,
Even if it were in the form of a beam, the beam diameter would be significantly larger than the diameter of the laser beam L, so if it was diffused by the milky white translucent acrylic plate 3,
It is detected by solar cell 4 and solar cell 5 with almost no difference.

Therefore, by calculating the output difference between the solar cells 4 and 5 using the differential amplifier 6, the influence of external light is canceled and only the information possessed by the laser beam L is extracted.

Therefore, according to this position detection laser receiver 1, interruption of the laser beam L can be detected without being adversely affected by external light.

Another example is one in which photodiodes or the like are used in place of the solar cells 4 and 5.
Also, in place of the interference filter 2, a colored glass filter,
In place of the milky white translucent acrylic plate 3, a red translucent acrylic plate or the like may be used.

(Effects of the invention) According to the position detection laser receiver of the invention, the laser beam can be detected without being affected by external light, so malfunctions due to increased mixing of external light when the beam length is increased can be prevented. I can do it. By the way
When the effectiveness of the present invention was tested using a He-Ne laser, no malfunctions due to external light occurred even when the beam length was 10 m.

[Brief explanation of drawings]

FIG. 1 is a schematic structural explanatory diagram of an embodiment of a laser receiver for position detection according to the present invention. 1... Laser receiver for position detection, 2... Interference filter, 3... Milky white translucent acrylic plate, 4, 5
...Solar cell, 6...Differential amplifier.

Claims (1)

[Claims for Utility Model Registration] 1 (a) Light selective introduction means for selectively introducing light of the same wavelength as a laser beam. (b) A light diffusion means for diffusing the light introduced by the light selective introduction means. (c) A laser beam sensor that mainly detects the diffused light of the laser beam introduced by the light selective introduction means. (d) an external light sensor that mainly detects the diffused external light introduced by the light selective introduction means; and (e) a difference signal output that outputs an output difference signal between the laser light sensor and the external light sensor. 1. A position detection laser receiver, comprising a means for detecting a position. 2. The laser receiver for position detection according to claim 1, wherein the light selective introduction means is an interference filter. 3. Utility model registration claim 1 or 2, in which the light diffusing means is a milky-white translucent synthetic resin plate.
Laser receiver for position detection as described in . 4 Utility model registration claim 1 in which both the laser light sensor and the external light sensor are solar cells
3. The position detection laser receiver according to any one of items 3 to 3.