JPH02269990A - Optical switch device - Google Patents

Abstract

PURPOSE:To enable body detection with high accuracy and to prevent an operation point from shifting with time by providing knife edges which are associated with actuators movably at right angles to an optical axis of projection and discriminating the level of a photodetection signal which passes an image formation position. CONSTITUTION:Two actuators 21 and 22 which are provided in a case 10 movably are arranged on one straight line and knife edges 21a - 24a provided at their internal ends are so arranged that projection light travels to a focus position where the light is converged by a ball lens 15. Then when the edges 21a and 22a or 23a and 24a move toward a spot SP, the projection light is cut off, the quantity of photodetection by a photodiode 16 decreases, and the output signal of the photodiode 16 varies in level with the movement quantities of the edges 21a - 24a, so the variation is discriminated by using a proper threshold value to obtain a switch output. This device can have repetition accuracy of about 0.1mum of a light emission diameter and the mechanism for obtaining the switch output includes no contact part, so a switch operation point which never shifts with time can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention A knife edge that moves in conjunction with the movement of an actuator is provided so that the focal position of the converging projection light moves back and forth in a direction perpendicular to the optical axis of the projection light, and the focal position Receives the light that has passed through it. By discriminating the level of the light reception signal, the presence or absence of an object that moves the actuator is detected. Thereby, it is possible to improve the accuracy of object detection. Further, by eliminating contact parts such as contacts, it is possible to eliminate changes in the operating point over time.

In addition, in those equipped with three or more actuators,
These actuators are provided with respectively interlocking knife edges, and these three or more knife edges are shifted in the optical axis direction and arranged so that they partially overlap. This prevents the knife edges from colliding with each other, and also prevents errors from occurring due to vibration.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch device that optically detects, inside a switch, an object that comes into contact with an actuator and moves the actuator.

A conventional switch device has a contact that is linked to an actuator, and detects the presence or absence of an object based on whether or not the contact is in contact. Since it is a contact type, the repeatability of the switch operating point was about 1 μm. In addition, deterioration over time due to deformation of the contact portion is another problem that cannot be avoided in principle.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical switch device that is highly accurate and exhibits almost no change over time.

The optical switch device according to the present invention includes a light source that emits projected light, a lens system for forming an image of the projected light from the light source, and a lens system that is movably supported in a direction perpendicular to the optical axis of the projected light, and an actuator that moves the light source. a knife edge that advances and retreats from the imaging position of the projected light, a light receiving element that receives the light that has passed through the imaging position, and a processing circuit that generates a switch output in response to a change in the output signal of the light receiving element. It is characterized by having

When the knife edge moves in a direction perpendicular to the optical axis of the projection light to the image formation position of the projection light, part or all of the projection light is blocked by the knife edge, so The rear light intensity varies depending on the position of the knife edge. This light intensity change is detected by the photoelectric conversion element, and the output signal of the photoelectric conversion element is compared with a predetermined value by a comparator or the like, and a switch output is generated.

According to this invention, when a light source with a sufficiently small one light emitting area (for example, 100 μm in diameter) is used, the spot of the projected light can also be narrowed down to about the size of this light emitting area. A repeatability of 1/1000 or less (about 0.1 μm) of the emission diameter can be obtained, and a highly accurate switch device can be realized.

Further, in this invention, since there is no contact part in the mechanism for obtaining the switch output, a switch operating point that hardly changes over time can be obtained.

The knife edge can be moved forward and backward from any direction, and since it is possible to provide multiple knife edges that move forward and backward from multiple directions, it is also possible to obtain switching outputs from multiple actuators that move in multiple directions. becomes possible.

The invention further includes a plurality of actuators.

At least three knife edges each driven by these actuators advance and retreat from different directions to the imaging position of the projected light, wherein the three or more knife edges move toward the imaging position of the projection light. The actuators are arranged at different positions in the optical axis direction so as not to collide with each other when they enter the actuator, and the ones located in the middle are formed thinner than those located at both ends. - A feature is that the tips of the edges are arranged so that a part of them overlaps in the optical axis direction.

If multiple knife edges approach the imaging position from different directions and move back and forth on the same plane, these knife edges
If the edges enter the imaging position at the same time, there is a risk that the knife edges will collide with each other. According to this invention,
Since the plurality of knife edges are arranged with their positions shifted in the optical axis direction, the knife edges do not collide with each other. Furthermore, among the three or more knife edges, the one located in the middle is formed thinner than the one located at both ends, so all of these knife edges must be placed at the imaging position and very close to it. All knife edges block the projected light at approximately the same position.

Furthermore, according to the present invention, the tips of the knife edges are arranged so as to partially overlap each other at the original position (initial position) of the actuator. Knife located in the middle
Since the edges are thin, they tend to vibrate, or, according to the present invention, the tips of the knife edges are partially sandwiched between thicker knife edges, which are less likely to vibrate, located at both ends, so that vibrations are prevented.

Description of examples FIG. 1 shows an embodiment of the invention.

Inside the case 10 of the optical switch device, a light emitting diode (LED) 11 is installed as a light source. Ball lens +2.1
5. Half mirror 13, monitor photodiode 14
and a signal photodiode 1G are arranged.

The LED II has a light emitting diameter of, for example, 100 μm, and is placed at the focal point of the ball lens 12 (eg, 5 mm in diameter). The emitted light of LED II is collimated by ball lens 12. A portion of this collimated emitted light is deflected by a half mirror 13 and received by a monitoring photodiode 14. The remaining portion of the collimated output light travels straight and is focused by a ball lens L5C (eg, 5 mm in diameter). The light spot diameter of this convergent light is 1001 mm, which is the same as the emission diameter of LED II. tm
becomes. After the convergent light passes the focal point, it is diffused and received by the signal photodiode 1G.

In a plane perpendicular to the optical axis of the above projected light.

Two actuators 21 and 22 are provided inside the case 10 of the optical switch device so as to be able to move forward and backward. The portions of the actuators 21 and 22 exposed outside the case 10 are surrounded by a bellows 25. Moreover, the actuator 21. 22 is urged outward by a spring 26, and its protrusion amount is regulated by a stopper.

The two actuators 21, 22 are arranged in a straight line and are provided with knife edges 21a, 22a at their inner ends. These knife edges 21a, 22
a is arranged so that the projected light travels towards its focal point where it is focused by the ball lens 15. Further, the knife φ edges 21a and 22a are slightly shifted in the optical axis direction.

FIG. 2 shows the relationship between the projected light spot (image formation of the light emitting area of LEDll) SP, the knife edges 21a and 21b that advance and retreat from this spot position, and the light receiving area lea of the photodiode 16. .

When the knife edge 21a or 21b advances toward the spot SP, the projected light is blocked and the photodiode IG
The amount of light received decreases. Knife edge 21a or 22b (i.e. actuator 21 or 22)
For the amount of movement (push amount).

The level of the output signal of photodiode IB changes as shown in FIG. As will be discussed below, the switch output can be obtained by discriminating the output signal of photodiode 16 by an appropriate (eg, intermediate level) threshold level. Since the switching resolution is about 1/1000 of the diameter of the optical spot SP, a switching accuracy of about 0.1 μm can be obtained.

In the optical switch device shown in FIGS. 1 and 2, since two actuators 21 and 22 are provided, it is possible to deal with moving objects (sensing objects) coming from two directions. Actuators are provided in four directions, and the chain lines 2 in Fig. 2 are attached to the inner ends of these actuators.
By providing knife edges, including those shown at 3a and 24a, detection in four directions becomes possible. Also in this case, all the knife edges 21a to 24a are slightly shifted in the optical axis direction.

3 and 4 show the electrical configuration of the optical switch device. This electric circuit is assembled on a printed circuit board built into the case 10.

In FIG. 3, the output signal of the monitor photodiode 14 is transferred to a buffer circuit (amplifier, I/V conversion circuit, etc.) 33.
The light is supplied to the light emission amount control circuit 32 through the. On the other hand, the reference potential generated from the high-precision reference potential generation circuit 31 is also given to the control circuit 32. The control circuit 32 responds to the comparison result of these two inputs.

LEDII so that the amount of light emitted from LEDII is always constant
control.

The output signal of the signal photodiode 16 is sent to the buffer 34.
The signal is applied to the comparator circuit 35 via the. The comparison circuit 35 is supplied with a reference potential (threshold level) output from a high precision reference potential generation circuit 36.

The comparison circuit 35 compares the level of the output signal of the photodiode 16 with the threshold level and provides the result to the output circuit 37, so that the output circuit 37 outputs a switch output converted into an appropriate format. Ru.

In FIG. 4, LED II is driven by a constant current circuit 41. The output signals of the signal photodiode 1B and the monitor photodiode 14 are applied to the comparison circuit 44 through buffer circuits 42 and 43, respectively. The output signal of the monitor photodiode 14 is sent to the buffer circuit 4.
3 is converted to an appropriate level accordingly and used as a threshold level. Comparison circuit 44
The comparison result is given to the output circuit 45, and the output circuit 45 generates a switch output. According to the circuit shown in Fig. 4, the LE is
Even if the output of DII fluctuates, the threshold level changes accordingly, so it is possible to achieve high accuracy and to simplify one circuit configuration.

FIG. 6 shows an example in which a semiconductor laser 51 is used as the light source. The light emitting point of the semiconductor laser 51 is approximately 1 μm x 4 μm
Therefore, the condensed spot by the optical system 52 is also approximately the same, and the characteristics of the output signal of the photodiode 16 show a rapid change as shown in FIG. As a result, 1n11
An optical switch device with an unprecedented high precision of ~4 nm will be realized. It is desirable to increase the area of the light receiving portion of the photodiode so that the photodiode 16 can receive all of the light diffracted by the knife edges 21a and 22a.

FIG. 8 shows yet another embodiment. All of the above-mentioned optical switch devices are of the transmission type.

The device of FIG. 8 is of the reflective type.

The signal photodiode 16 is provided to face the monitor photodiode I4. Additionally, four knife edges 21a to 24a are provided, allowing detection in four directions. Knife edge 21a-24a
As shown enlarged in FIG. 9, they are arranged one on top of the other in the optical axis direction, and the middle two (22a and 23a) are formed thin. Further, the knife edges 21a to 24a are formed in black so as to absorb light. A concave surface m27 is provided at the rear of these knife edges 21a to 24a.

Of the light focused by the ball lens 15, the light that hits any of the knife edges 21a to 24a is absorbed by that knife edge. Only the light not blocked by the knife edge is reflected by the concave mirror 27 and reflected by the ball lens 15. The light passes through the second mirror 13 and enters the signal photodiode 16 . The characteristics of the output signal of the signal photodiode 16 are the same as those shown in FIG. 5, and the electric circuits shown in FIGS. 3 and 4 can be used.

FIGS. 10 to 12 show still other examples. This optical switch device is of the same transmission type as that shown in FIG. 1, and the same components as shown in FIG. 1 are given the same reference numerals. Actuators movable in four orthogonal directions are provided (only actuators 21, 22 are shown), and these actuators are provided with knife edges 2La, 21b,
21c and 21d are provided, respectively. These knives/tools/soldiers 21a to 21d are arranged slightly shifted in the optical axis direction.

Moreover, the two intermediate knife edges 23a and 22a are formed thin. Furthermore, when the actuators 21, 22, etc. are in their original positions (initial position: a position in which the sensing object is not acting, a position in which the spring 26 protrudes outward and the amount of protrusion is regulated by the stopper), the first 12
As shown in the figure, knife edges 21a, 22a,
23a and 24a are arranged so as to partially overlap each other. When the actuator is actuated by a sensing object from this state, the knife edge 21a moves toward the center, as shown by the chain line. Then, when the sensing object leaves the actuator, the knife edge returns to the position shown by the solid line.

In this embodiment as well, the output signal of the signal photodiode 16 is the same as that shown in FIG. 5, and the electric circuit shown in FIG. 3 or 4 can also be used. Since it has four actuators and four knife edges, it can detect objects in four directions.

If a plurality of knife edges 21a to 24a advance and retreat on the same plane, these knife edges 21a to 24a move back and forth on the same plane.
When the knife edges 24a simultaneously enter the spot position of the projected light (the imaging position of the light emitting area of the LED II), there is a possibility that the knife edges will collide with each other. According to this embodiment, the plurality of knife edges 21a to 24a are arranged with their positions shifted in the optical axis direction.
24a will not collide with each other. Moreover, the knife edge 22a located in the middle among the knife edges 21a to 24a,
Since knife 23a is formed thinner than those located at both ends 21a and 24a, these knives φ edges 21
a to 24a can all be placed at and in close proximity to the projected light spot position, with all knife edges 21a to 24a blocking the projected light at approximately the same location. Further, according to this embodiment, the tip ends of the knife edges 21a to 24a are arranged so as to partially overlap each other at the original position (initial position) of the actuator. The knife edges 22a and 23a located in the middle are thin and easily vibrate, but according to this embodiment, the knife edges 2
Part of the tips of 2a and 23a are always held between knife edges 21a and 24a located at both ends, which are thick and therefore less likely to vibrate, so that vibrations are prevented.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the invention; FIG. 2 is a plan view of a knife edge; FIGS. 3 and 4 are block diagrams showing electrical circuits of the optical switch device;
FIG. 5 is a graph showing the output characteristics of the signal photodiode. FIG. 6 is a partial sectional view showing another embodiment, and FIG. 7 is a graph showing the output characteristics of the signal photodiode. FIG. 8 is a sectional view showing still another embodiment, and FIG. 9 is an enlarged sectional view showing the arrangement of the knife edge. FIG. 10 is a sectional view showing still another embodiment, FIG. 11 is an enlarged sectional view showing the arrangement of the knife edges, and FIG. 12 is a plan view showing the arrangement of the knife edges in an enlarged manner. 11...LED. 12, 15...Ball lens. 16...Signal photodiode. 21, 22...Actuator. 21a, 22a, 23a, 24a...knife edge. 35, 44... Comparison circuit. 37, 45... Output circuit. 52...Lens. that's all

Claims (2)

[Claims] (1) a light source that emits projection light; a lens system for forming an image of the projection light from the light source; supported movably in a direction perpendicular to the optical axis of the projection light;
A knife edge that advances or retreats from the imaging position of the projected light by movement of an actuator, a light receiving element that receives the light that has passed through the imaging position, and a switch output generated in response to a change in the output signal of the light receiving element. An optical switch device equipped with a processing circuit. (2) comprising a plurality of actuators and at least three knife edges that are each driven by these actuators and move forward and backward from different directions to the imaging position of the projected light, and these knife edges move toward the imaging position of the projection light; The actuators are arranged at different positions in the optical axis direction so as not to collide with each other when the actuator enters the actuator, and the actuator located in the middle is thinner than the actuator located at both ends. The optical switch device according to claim 1, wherein the knife edges are arranged so that a portion of their tips overlap in the optical axis direction.