JPS6031143Y2 - photoelectric switch - Google Patents

Description

[Detailed Description of the Invention] An object of the present invention is to provide a photoelectric switch that allows accurate optical axis adjustment with ease.

As is well known, in order to use a photoelectric switch in good condition, it is necessary to adjust the optical axis so that the optical axes of the light emitter and light receiver coincide. A method has been proposed in which the optical axis is adjusted with the sensitivity lowered, and then the sensitivity is increased.

In other words, when the sensitivity is lowered, it is necessary to adjust the optical axis with a high degree of precision. The sensitivity margin is large and stable operation can be expected.

Conventionally, as a means for reducing the sensitivity of a photoelectric switch during optical axis adjustment, a switch means is connected to a light receiving circuit or a light projecting circuit, and the sensitivity of the light receiving section is increased or decreased or the amount of light emitted is increased or decreased by electrically switching.

However, changing the sensitivity using electrical switching means has drawbacks such as reduced reliability and complicated electrical circuitry.

For example, if a tangential switch is used,
The operation of the entire photoelectric switch was sometimes affected by poor contact of the switch.

In other words, a contact switch can achieve the desired operation when a certain amount of current is passed through it, but recent photoelectric switches tend to consume very little current, and the current in the circuit that switches sensitivity is reduced. The number is even smaller and has reached the point where a contact switch cannot operate stably.

Furthermore, the photoelectric switch itself is installed in a location with fairly harsh environmental conditions, and the switches incorporated therein are also placed under the same environmental conditions.

These factors combine to reduce the reliability of the switch, that is, the reliability of the photoelectric switch.

If a non-contact type switch was adopted as the switch means, the above-mentioned drawbacks would be eliminated, but the electric circuit would become far more complex, and the number of circuit components that had little to do with the original performance of the photoelectric switch would increase, which would increase costs and reduce reliability. Problems arise from a sexual perspective.

In view of these points, the present invention attempts to achieve the same effect by switching the sensitivity by mechanical means at the light stage, without making any changes to the electric circuit.

That is, when adjusting the optical axis, the light intensity is decreased to lower the sensitivity of the photoelectric switch, and when the adjustment is completed, the light intensity is increased to increase the sensitivity of the photoelectric switch, and from then on, it is used with a high light intensity. The aim is to obtain stable operation.

This will be explained below with reference to the drawings.

In FIG. 1, a photoelectric element 1, a mask 2, and a lens 3 are arranged in this order on the optical axis xX, and the mask 2 has a hole 21 in the center that is larger than the photoelectric element 1 and smaller than the lens 3.
is provided, and the mask 2 is movable back and forth in the direction of the optical axis XX.

In this configuration, when the mask 2 is brought sufficiently close to the photoelectric element 1, the optical path between the lens 3 and the photoelectric element 1 is not cut at all by the mask 2, and when the photoelectric element 1 is a light receiving element, the optical path enters the lens 3. All light rays are incident on the photoelectric element 1, and when the photoelectric element 1 is a light projecting element, the light rays emitted from the photoelectric element 1 are effectively projected onto the lens 3.

When the mask 2 is brought close to the lens 3 as shown by the dotted line in FIG.
The closer the lens is to the lens 3, the larger it becomes.

That is, the closer the mask 2 is to the lens 3, the lower the sensitivity of the photoelectric switch becomes, and conversely, the closer the mask 2 is to the photoelectric element 1, the higher the sensitivity becomes.

Therefore, if you move the mask 2 close to the lens 3 to adjust the optical axis so that it can operate normally, then fix the photoelectric switch, and then move the mask 2 close to the photoelectric element 1 and actually use it, the photoelectric switch will have enough room. Since it is operated under the amount of light, the stability of operation is not hindered by slight deviation of the optical axis due to vibration or the like or a decrease in the amount of light due to dirt on the lens surface.

As can be seen from this example, the present invention does not require any modification to the electrical circuit, and there is no concern that the reliability of the photoelectric switch will deteriorate in this respect.

The above-mentioned basic configuration can be applied in the same way to a normal photoelectric switch having a condensing optical system other than a lens, such as a concave mirror or a parabolic mirror.

Furthermore, the movement of the mask 2 does not have to be parallel to the optical axis XX,
It is not necessary to make holes 21 in the mask 2, and the same effect can be obtained by making only this part transparent.

Furthermore, if it is possible to simultaneously move the mask 2 and act on other mechanisms that must be used during use,
The mask 2 can be automatically moved to a position with low sensitivity during optical axis adjustment and high sensitivity during use without paying special attention to handling.

Figure 2 shows such an embodiment, in which a light emitter and a light receiver are housed in one case, and the present invention is applied to the light emitter of a reflective light emitter/receiver that operates using reflected light from an object to be detected. The optical system uses a concave mirror, the mask does not move parallel to the optical axis, and the hole in the mask is circular (the mask can be moved, the terminal cover can be attached and removed, and the optical axis can be fixed after adjustment at the same time). This is an example of how to do this.

That is, when the set screw 4 is removed together with the rotated terminal cover 5 during installation, the slide fitting 6 slides to the right, and the tapered part of the upper part of the connecting rod 7 slides into the six 61, and the connecting rod 7
moves upward, the mask fitting 8 is pulled by the governor spring 82 and rotates counterclockwise about the fulcrum 91, and the 681 of the mask fitting 8 moves away from the light projecting element 10.

681 is an ellipse that is long in the vertical direction so that the mask metal fitting 8 does not deviate from the optical axis YY too much when it rotates around the fulcrum 91.

When the light beam 681 moves away from the light projecting element 10, among the light beams projected from the light projecting element 10 onto the concave mirror 9, only those close to the optical axis YY pass through the light beam 681, reach the concave mirror 9, and are projected in the target direction. The light beams away from the mask fitting 8 are even cut off by the mask fitting 8, and as a result, the amount of light projected from the light projecting section is reduced.

In this state, the terminal fitting 11 is exposed, and the action of the set screw 4 to prevent the light emitting/receiving section 12 from rotating around @AA is also released.

Therefore, in this state, the optical axis can be adjusted by wiring the terminal fitting 11 and rotating the light emitting/receiving section 12 around the axis AA.

After that, when the terminal cover 5 is put on and the setscrew 4 is tightened, the slide fitting 6 slides to the left and the connecting rod 7 is pushed down by the action of a part of the taper at its upper part.
The mask metal fitting 8 rotates clockwise about the fulcrum 91, the 681 approaches the light projecting element 10, and the amount of light projected from the light projecting element 10 onto the concave mirror 9 is increased.

If the set screw 4 is further tightened, its tip will align with the light emitting/receiving section 12.
The light emitting/receiving part 12 is fixed so that it does not rotate by hitting the rotation stopper 13 of the light emitting/receiving part 12.

That is, in this example, in the process of wiring to the terminal fitting 11, adjusting the direction of the light emitting/receiving section 12, and fixing it, which are necessary for a normal photoelectric switch, the sensitivity of the photoelectric switch is automatically raised or lowered, making it difficult to handle. It's extremely convenient.

As explained above, according to the present invention, a photoelectric element, a mask having a light-transmitting part, and an optical system are arranged in this order, and the light-transmitting part of the mask can be moved back and forth approximately along the optical axis. By doing so, it is possible to obtain a photoelectric switch in which the sensitivity can be raised or lowered without any modification to the electric circuit, and the optical axis can be adjusted appropriately.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts of a basic embodiment suitable for explaining the principle of the present invention, and FIG. 2 is a partially cutaway side view of another embodiment of the present invention. 1...Photoelectric element, 2...Mask, 21
...Small hole, 3...Lens, XX...Optical axis.

Claims (1)

[Scope of utility model registration request] A mask provided with a light-transmitting part is provided between the photoelectric element and the optical system so as to be movable in conjunction with attachment and detachment of the terminal cover, and when the terminal cover is attached, the light-transmitting part is close to the photoelectric element, and the other A photoelectric switch characterized in that the transparent part moves away from photoelectrons when the terminal cover is removed.