JP2906250B2 - Optical switch device - Google Patents

Description

Description: 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 moves an actuator by contacting 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 the presence or absence of the contact of the contact. Because of the contact type, the repeatability of the switch operating point was about 1 μm. In addition, a change with time due to deformation of the contact portion is one of the problems that cannot be avoided in principle.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical switch device which is highly accurate and hardly changes with time.

An optical switch device according to the present invention includes a light source that emits projection light, a lens system for forming an image of the projection light from the light source, an actuator that is movably supported and moves by contact with an object, and that is linked to the movement of the actuator. A knife edge for moving the image formation position of the projection light in a direction perpendicular to the optical axis of the projection light, a light receiving element for receiving light passing through the image formation position, and a level of an output signal of the light reception element And a processing circuit for generating a switch output indicating whether the amount of movement of the actuator due to contact with an object has exceeded a predetermined value.

When the object comes into contact with the actuator and the actuator moves, the knife edge moves in the direction perpendicular to the optical axis of the projected light into the image forming position of the projected light in conjunction with the movement of the actuator. Since part or all of the light is shielded by the knife edge, the light intensity behind the imaging position changes depending on the position of the knife edge. This light intensity change is detected by the light receiving element, and the level of the output signal of the light receiving element is compared with a predetermined threshold level by a comparator or the like. In accordance with the result of the comparison, a switch output indicating whether the amount of movement of the actuator due to the contact of the object has exceeded a predetermined value is generated.

According to the present invention, when a light source having a sufficiently small light emitting area (for example, a diameter of 100 μm) is used, the spot of the projection light can be reduced to about the size of the light emitting area. Therefore, a highly accurate switch device can be realized. As an example, a repetition accuracy of 1/1000 or less (approximately 0.1 μm) of the emission diameter can be obtained.

Further, according to the present invention, since there is no contact portion in the mechanism for obtaining the switch output, there is almost no change with time.

The knife edge can be moved back and forth from any direction perpendicular to the optical axis of the projected light, and a plurality of knife edges can be provided in a plurality of directions, so that a plurality of actuators moving in a plurality of directions can be provided. And a switching output can be obtained. That is, it is possible to detect the amount of movement of the actuator due to the object coming into contact with the plurality of actuators from multiple directions.

The present invention further provides at least three actuators and at least three knife edges respectively driven by these actuators and moving back and forth from different directions to the imaging position of the projection light. More than one knife edge is shifted in the direction of the optical axis so that it does not collide with each other when it enters the imaging position, and the middle one is thinner than the one located at both ends. The knife edge is arranged so that a part of the tip of the knife edge overlaps in the optical axis direction at the original position of the actuator.

If at least three knife edges entering the imaging position from different directions move back and forth on the same plane, the knife edges may collide when these knife edges enter the imaging position at the same time. According to the present invention, since the plurality of knife edges are displaced in the optical axis direction, the knife edges do not collide with each other. In addition, since the middle one of the three or more knife edges is formed thinner than the ones at both ends, all of these knife edges should be placed at the imaging position and very close to it. All knife edges block the projected light at approximately the same location.

Further, according to the present invention, at the original position (initial position) of the actuator, the distal ends of the knife edges are arranged so as to partially overlap each other. The knife edge located in the middle is thin and easily vibrated, but according to the present invention, a part of the tip of the knife edge is sandwiched between the thick and therefore hard to vibrate knife edges located at both ends, so that the vibration of the knife edge is reduced. The occurrence is prevented.

FIG. 1 shows an embodiment of the present invention.

A light emitting diode (LED) 11 as a light source, ball lenses 12, 15, a half mirror 13, a monitoring photodiode 14, and a signal photodiode 16 are arranged inside a case 10 of the optical switch device. The LED 11 has an emission diameter of, for example, 100 μm, and has a ball lens 12.
(For example, 5 mm in diameter). The light emitted from the LED 11 is collimated by the ball lens 12.
A part of the collimated light is deflected by the half mirror 13 and received by the monitoring photodiode 14. The rest of the collimated outgoing light goes straight,
The light is focused by the lens 15 (for example, 5 mm in diameter). The light spot diameter of this convergent light is 100 μm, the same as the light emission diameter of LED11.
Becomes The convergent light diffuses after passing through the focal position and is received by the signal photodiode 16.

In a plane perpendicular to the optical axis of the projection light, two actuators 21 and 22 are provided so as to be able to advance and retreat inside the case 10 of the optical switch device. The portions of the actuators 21 and 22 exposed outside the case 10 are surrounded by bellows 25. The actuators 21 and 22 are urged outward by a spring 26, and the amount of protrusion is regulated by a stopper. The two actuators 21, 22 are arranged in a straight line, and at their inner ends knife edges 21a,
22a is provided. These knife edges 21a, 22a
Are arranged so that the projected light travels toward its focal position where it is collected by the ball lens 15. The knife edges 21a and 22a are slightly shifted in the optical axis direction.

Fig. 2 shows the projected light spot (image of the light-emitting area of LDE11) SP and the knife edge moving back and forth at this spot position
This shows the relationship between 21a and 21b and the light receiving area 16a of the photodiode 16. When the knife edge 21a or 21b advances toward the spot SP, the projection light is blocked, and the amount of light received by the photodiode 16 decreases. Knife edge
The level of the output signal of the photodiode 16 changes as shown in FIG. 5 with respect to the moving amount (pressing amount) of the actuator 21a or 22b (ie, the actuator 21 or 22). As described below, a switch output can be obtained by discriminating the output signal of the photodiode 16 with an appropriate (eg, intermediate level) threshold level. Since the switching resolution is about 1/1000 of the diameter of the light 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, a moving object (detected object) coming from two directions can be dealt with. Actuators are provided in four directions, and chain lines 23a and 24a
If knife edges are provided, including those indicated by, 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 incorporated in the case 10.

In FIG. 3, the output signal of the monitoring photodiode 14 is supplied to a light emission amount control circuit 32 through a buffer circuit (amplifier, I / V conversion circuit, etc.) 33. On the other hand, the reference potential generated from the high-precision reference potential generation circuit 31 is also supplied to the control circuit 32. The control circuit 32 controls the LED 11 so that the light emission amount of the LED 11 is always constant according to the comparison result of these two inputs.

The output signal of the signal photodiode 16 is supplied to the comparison circuit 35 via the buffer 34. The comparison circuit 35 is supplied with a reference potential (threshold level) output from the high-precision reference potential generation circuit 36, and the comparison circuit 35 compares the level of the output signal of the photodiode 16 with the threshold level. The result is supplied to the output circuit 37, so that the output circuit 37 outputs a switch output converted into an appropriate form.

In FIG. 4, the LED 11 is driven by a constant current circuit 41. The output signals of the signal photodiode 16 and the monitor photodiode 14 are buffer circuits 42 and 43, respectively.
, To the comparison circuit 44. The output signal of the monitoring photodiode 14 is converted to an appropriate level by the buffer circuit 43 and used as a threshold level. The comparison result of the comparison circuit 44 is the output circuit 45
And the output circuit 45 generates a switch output.
According to the circuit shown in FIG. 4, even if the output of the LED 11 fluctuates due to changes in temperature, power supply voltage, luminous efficiency, etc., the threshold level changes accordingly, so that high accuracy can be achieved. In addition, the circuit configuration can be simplified.

FIG. 6 shows an example in which a semiconductor laser 51 is used as a light source. Since the light emitting point of the semiconductor laser 51 is about 1 μm × 4 μm, the condensed spot by the optical system 52 is almost the same, and the characteristics of the output signal of the photodiode 16 show a rapid change as shown in FIG. As a result, an optical switch device with a high accuracy of 1 nm to 4 nm, which has never been achieved before, is realized. knife·
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 diffracted light by the edges 21a and 22a.

FIG. 8 shows still another embodiment. All of the above optical switch devices are of the transmission type, while the device of FIG. 8 is of the reflection type.

The signal photodiode 16 is provided so as to face the monitor photodiode 14. In addition, four knife edges 21a to 24a are provided to enable detection in four directions. As shown in FIG. 9, the knife edges 21a to 24a are arranged so as to overlap with each other in the optical axis direction, and the middle two (22a and 23a) are formed thin. The knife edges 21a to 24a are formed in black so as to absorb light. Behind these knife edges 21a-24a are concave mirrors
27 are provided.

Of the light condensed by the ball lens 15, light hitting any of the knife edges 21a to 24a is absorbed by the knife edge. Only the light that is not blocked by the knife edge is reflected by the concave mirror 27 and the ball lens 15,
The light enters the signal photodiode 16 via the half mirror 13. 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.

10 to 12 show still another example. This optical switch device has the same transmission type as that shown in FIG. 1, and the same components as those shown in FIG. 1 are denoted by the same reference numerals. Actuators movable in four orthogonal directions are provided (only the actuators 21 and 22 are shown), and these actuators are provided with knife edges 21a, 22a, 23a and 24a, respectively. These knife edges 21a-24a
Are slightly offset in the direction of the optical axis, and
The two knife edges 23a and 22a are formed thin. Further, when the actuators 21 and 22 are at the original position (initial position: a position where the sensing object is not acting, a position where the protrusion protrudes outward by the spring 26 and the amount of protrusion is regulated by the stopper), As shown in FIG. 12, the knife edges 21a, 22a, 23a, and 24a are arranged so as to partially overlap each other. In this state, when the actuator is actuated by the sensing object, the knife edge enters the center as shown by the chain line with respect to the knife edge 21a.
When the object moves away from the actuator, the knife
The edge returns to the position shown by the solid line.

Also in this embodiment, 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 be used. With four actuators and four knife edges, object detection in four directions is possible.

If a plurality of knife edges 21a to 24a advance and retreat on the same plane, the knife edges 21a to 24a simultaneously enter the spot position of the projected light (the imaging position of the light emitting area of the LED 11). Comrades may collide. According to this embodiment, since the plurality of knife edges 21a to 24a are displaced in the optical axis direction, the knife edges 21a to 24a do not collide with each other. Also, the knife edges 21a to 24a are formed so that the middle ones 22a and 23a are formed thinner than the two ends 21a and 24a.
~ 24a can be located at and very close to the projected light spot, and all knife edges
21a to 24a block the projection light at almost the same position. Further, according to this embodiment, the tips of the knife edges 21a to 24a are arranged so as to 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 thus easily vibrate, but according to this embodiment, the knife edges 21a and 24a are thick because the ends of the knife edges 22a and 23a are located at both ends and are therefore hard to vibrate. , The occurrence of vibration is prevented.

[Brief description of the drawings]

1 is a sectional view of an optical switch device, FIG. 2 is a plan view of a knife edge, FIGS. 3 and 4 are block diagrams showing an electric circuit 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 output characteristics of a signal photodiode. FIG. 8 is a sectional view showing still another embodiment, and FIG. 9 is a sectional view showing an enlarged arrangement of knife edges. FIG. 10 is a sectional view showing still another embodiment, FIG. 11 is a sectional view showing an enlarged arrangement of knife edges, and FIG. 12 is a plan view showing an enlarged arrangement of knife edges. 11… LED, 12,15… Ball lens, 16… Signal photodiode, 21,22 …… Actuator, 21a, 22a, 23a, 2
4a: Knife edge, 35, 44: Comparison circuit, 37, 45: Output circuit, 52: Lens.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kohei Tomita Tateishi Electric Co., Ltd. (10) Hanazono Todocho, Ukyo-ku, Kyoto, Kyoto Prefecture (56) References JP-A-58-168921 (JP, A) JP-A-60-3529 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01V 8/12 G01J 1/02 G01B 11/00 H01H 35/00

Claims (2)

(57) [Claims] A light source for emitting projection light; a lens system for forming an image of the projection light from the light source; an actuator that is movably supported and moves upon contact with an object; A knife edge for moving the image forming position of the projection light in a direction perpendicular to the optical axis of the projection light, a light receiving element for receiving the light passing through the image forming position, and a level of an output signal of the light receiving element. A processing circuit that discriminates at a threshold level and generates a switch output indicating whether or not the amount of movement of the actuator due to contact with an object exceeds a predetermined value. And at least three actuators respectively driven by the actuators and moving back and forth from different directions to the image forming position of the projection light.
Knife edges, which are displaced in the direction of the optical axis so that they do not collide with each other when they enter the above-mentioned image forming position, and the intermediate ones are provided at both ends. The light according to claim 1, wherein the light is formed so as to be thinner than the one located thereon, and further, a part of the tip of the knife edge is overlapped in the optical axis direction at the original position of the actuator. Switch device.