JPH06168652A - Distance setting type photoelectric switch - Google Patents

Abstract

PURPOSE:To set a distance without changing a setting distance by enlarging a lens area to a case. CONSTITUTION:A worm gear 13 is rotated, and a cam 12 meshed with this is rotated. A holder 7 is arranged so as to come into contact with one end of the cam 12, and the holder 7 is rotated, and an angle between the light projecting axis 2a and the light receiving axis 5a is changed. Thereby, a setting distance L is changed. The division to show the setting distance is arranged in the cam 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance setting type photoelectric switch used for discriminating whether the distance to a detection target is before or after.

[0002]

2. Description of the Related Art A distance setting type photoelectric switch is a photoelectric switch for determining whether an object to be detected is closer or farther than a set distance, and a triangulation method is generally used. FIG. 11 is a diagram showing a configuration of an optical system of a general distance setting type photoelectric switch. In the figure, a light emitting diode 101 is a light projecting element, which irradiates a light beam to an object detection region via a light projecting lens 102. Then, the light receiving lens 10 is inclined at a predetermined angle with respect to the light beam.
3 and a light receiving element 104 such as a position detecting element.
The set distance L is on the extension of the line connecting the centers of the light receiving lens 103 and the light receiving element 104 and the intersection of the center line of the light projecting light beam.

In order to change the set distance, for example, as shown in Japanese Utility Model Laid-Open Nos. Sho 63-187237 and Sho 63-102135, the distance between the light emitter and the light receiver is moved. A configuration has been proposed in which the set distance is changed. In such a photoelectric switch, in order to change the set distance, a groove is provided in a cylindrical operation member, and the light receiving portion is moved in parallel to set the distance.
Further, Japanese Patent Application Laid-Open No. 61-241616 proposes a structure in which a mirror for reflecting the received light is rotated by a screw to change the light receiving position on the light receiving element.

However, in such a first conventional example, since the distance is set by rotating the operating member, a stronger force is applied while the operating member is rotating to the end of the movable range. If this happens, the moving member may be destroyed. Further, there is a drawback in that it is necessary to secure a moving area of the lens for moving the lens, and the area of the lens cannot be made larger than the outer shape of the case. Further, since the rotation angle of the operating member is displayed as the set distance as it is, the operating member cannot be rotated many times, which makes it difficult to finely adjust the set distance.

Further, in the second conventional example, since the operation member for setting the distance is of the multi-rotation type and has the endless structure, the area of the lens can be increased, but the endless structure is provided by the springs of the worm and the gear. Therefore, the mirror may move and the set distance may change before the gear leaves the worm and meshes again. Therefore, there is a drawback that the set distance cannot be recognized. Further, since there is no display means for displaying the number of rotations, it is difficult to know how many rotations the operating member has been made, and thus it is difficult for the operator to clearly determine the set distance.

[0006]

The invention of claim 1 of the present application has been made in view of the above problems of the prior art, in which the lens area is increased with respect to the case, and the set distance varies. The purpose is to be able to set up to the end. In addition to this problem, an object of the invention of claim 2 of the present application is to make it possible to display the set distance. It is another object of the inventions of claims 3 and 4 to display the set distance even in the case of multiple rotations.

[0007]

According to a first aspect of the present invention, there is provided a light projecting portion fixed in a case, having a light projecting element, and irradiating a parallel light beam toward a detection region, a lens and a light receiving part. It has a light receiving part that holds the element and holds it rotatably, a worm gear that is rotatably held in the case, and a gear part that has one end meshing with the worm gear, and one end of which is the contact piece of the holder. And a cam that abuts and rotates the light-receiving shaft of the holder by its rotation.

According to the invention of claim 2 of the present application, the cam has a scale for displaying the distance on the outer periphery thereof, and the case has an opening whose position corresponding to the scale of the cam is open. It is a feature.

According to a third aspect of the present invention, a light projecting portion having a light projecting element for irradiating a parallel light beam toward a detection region and a light receiving axis intersect at a constant angle from the light projecting portion. A lens disposed on the lens and a light receiving portion having a holder to which the lens is fixed, an adjusting screw rotatably held in a case, and a female screw meshing with the adjusting screw. A frame that holds the light receiving element at one end, a rack formed on the outer periphery of the frame, a pinion gear that holds one end of the rack and is rotatably held in the case, and a pinion gear. Display means for displaying the position of the light receiving portion by being rotated.

According to the invention of claim 4 of the present application, a light projecting portion having a light projecting element for irradiating a parallel light beam toward a detection region and a light receiving axis intersect at a constant angle from the light projecting portion. A lens disposed on the lens and a light receiving portion having a holder to which the lens is fixed, an adjusting screw rotatably held in a case, and a female screw meshing with the adjusting screw. A frame that is held movably up and down and holds a light receiving element at one end, and a display means that is composed of a thin plate that has one end connected to the frame and the other end that is curved to a position close to the inner surface of the case, It is characterized by including.

[0011]

According to the invention of claim 1 of the present application having such a feature, the cam meshing with the worm gear is rotated by rotating the worm gear. Then, the angle of the holder whose one end abuts on the cam is changed, thereby changing the crossing angle of the light emitting / receiving unit and changing the set distance. Therefore, even if the worm gear is rotated to the end of the rotation range of the cam, the worm gear can be further rotated and the device is not damaged. According to the invention of claim 2, the set distance corresponding to the turning angle can be displayed by the scale provided on the cam. Further, in the inventions of claims 3 and 4, the frame is moved up and down by the adjusting screw, and the distance can be displayed in correspondence with the position of the frame.

[0012]

1 is a longitudinal sectional view showing the structure of a distance setting type photoelectric switch according to an embodiment of the present invention. In this figure, a light projecting element 3 and a light projecting lens 4 for irradiating light to an object detection area along an optical axis thereof are fixed to a light projecting section 2 below a case 1. A light receiving section 5 is arranged above the light projecting section 2. The light receiving section 5 has a conical holder 7 having a light receiving lens 6 on the front surface as shown in the figure. The holder 7 is rotatably held around the shaft 1a of the case 1 by an arcuate protrusion provided on the upper portion of the figure. A torsion coil spring 8 is attached to the shaft 1a of the case 1. One end of the torsion coil spring 8 is fixed to the printed circuit board 9, and the other end is engaged with the L-shaped protruding piece 6b of the holder 7. A position detecting element (position sensitive device, hereinafter referred to as PSD) 10 which is a light receiving element is attached to the top of the holder 7. Since the light receiving position of the PSD 10 differs depending on the reflection angle of the reflected light of the light beam from the light projecting unit 2, the position to the object is detected by the difference or ratio of the current outputs obtained at both ends.

A contact piece 11 having an arcuate curved portion on its upper surface is fixed to the holder 7. And this contact piece 11
The cam 12 is rotatably held by the case 1 so that one end of the cam 12 contacts with the case 1. As shown in the detailed front view and cross-sectional view of FIG. 2, the cam 12 has a structure in which a cylindrical member having a through hole and an annular groove in the center is integrated, and the outer peripheral portion thereof gradually increases as shown. It is configured to have a large radius. Further, a gear portion 1 having a plurality of teeth similar to those of a gear formed on a part of the outer circumference.
2a. A scale corresponding to the set distance is engraved on the outer periphery of the portion of the cam other than the gear portion 12a as described later.

The cam 12 is rotatably held by the shaft 1b of the case 1. Further, the case 1 is provided with a rectangular opening at a position corresponding to the scale of the cam 12, and a transparent lid is attached. A worm gear 13 is attached at a position adjacent to the cam 12 and in contact with the gear 12a of the cam. The head of the worm gear 13 is exposed to the outside of the case 1, and is rotatably held by rotating a slit (not shown) provided on the head. The case 1 is provided with a U-shaped torsion coil spring 14 around the shaft 1c. One end of the torsion coil spring 14 is fixed to the case 1, and the other end of the torsion coil spring 14 abuts on one end of the cam 12 depending on the rotation position of the cam 12 to regulate the rotation range of the cam 12. Further, a stopper 15 is provided on the case 1 at a position facing the holder 7. One end of the stopper 15 is inclined with respect to the case, and the inclined surface contacts with the rotation angle of the holder 7 to regulate the rotation range.

Next, the operation of this embodiment will be described. First, when the set distance is closest, as shown in FIG. 1, the angle θ formed by the light projecting axis 2a of the light projecting section 2 and the light receiving axis 5a of the light receiving section 5 is the largest. At this time, the rotation speed n of the worm gear 13 is assumed to be the minimum. At this time, for example, the scale provided on the cam 12 is in a state as shown in FIG. 5A when viewed from the rectangular window formed in the case 1.

When the worm gear 13 held by the case 1 is rotated clockwise, the contact position of the contact piece 11 comes into contact with the arcuate portion of the cam.
As shown in FIGS. 1 to 3, the holder 7 rotates rapidly.
Further, the rotation speed gradually increases, and accordingly, the cam 12 also gradually rotates as shown in FIG. Therefore, the scale of the cam 12 gradually changes from the state shown in FIG. 5A to the state shown in FIG. 5B. When the worm gear 13 is further rotated clockwise, the position of contact with the contact piece 11 is changed as shown in FIG. 3, whereby the holder 7 is rotated by being attracted by the torsion coil spring 8. In this state, the scale of the cam 12 is as shown in FIG. 5 (c), for example. Worm gear 1
If 3 is rotated, the worm portion of the worm gear 13 and the gear portion 12a of the cam 12 are disengaged, and the worm gear 13 stops at the position shown in FIG. In this state, the cam 12
Of the scale changes, for example, as shown in FIG. 5 (d) to (e).

Now, assuming that the rotation speed of the worm gear 13 is n and the angle formed by the light projecting axis 2a of the light projecting section 2 and the light receiving axis 5a of the light receiving section 5 is .theta., The change of the angle .theta.
Depending on the shape of the outer circumference of 2, for example, the curve A shown in FIG. This shows a state in which the angle θ sharply decreases as the rotation speed n increases. Then Figure 6
As shown by the curve A in (b), the change in the set distance L with respect to the rotation speed n becomes substantially a straight line.

On the other hand, if the change in the angle θ with respect to the rotational speed n changes linearly as shown by a straight line B in FIG. 6A, the projection axis 2a and the light receiving axis 5a intersect each other. The distance up to, that is, the set distance L to the object is shown in FIG.
As shown in (b), it changes significantly as shown by the curve B according to the change in the rotation speed n. Therefore, in the present invention, the rotation speed n and the set distance L are substantially linearized by greatly changing the angle θ while the rotation speed n is small. Therefore, as shown in FIG. 5, the scales marked on the cam 12 can be marked at substantially equal intervals, and the distance can be easily adjusted.

Next, FIGS. 7 and 8 are sectional views of a distance setting type photoelectric switch according to a second embodiment of the present invention. In this embodiment, the angle of the holder is constant, the distance is set by moving the holder in parallel from the light projecting portion, and an indicator mechanism for displaying the set distance is provided. In the figure, a case 21 has a light projecting portion 24 composed of a light projecting element 22 and a lens 23.
A light receiving unit 25 is provided on the upper part of the position 4. The light receiving unit 25 has a convex lens 27 on the front surface of a holder 26, and a position detecting element (PSD) 28 is provided at the focal position thereof. Then, an L-shaped frame 29 holding the PSD 28 is formed with a thread groove 29a of a female screw on the back as shown in the drawing.
By rotating the adjusting screw 30 from the outside of the case 21, the frame 29 can be slid up and down along the axis of the adjusting screw as shown in FIG. A rack is formed on the inner side wall of the frame 29, and a pinion gear 31 meshing with the rack is rotatably held by the case 21. An arm 32 is provided on the pinion gear 31, and a colored marker 32a is provided on the tip of the arm 32 so that the rotation angle can be identified from the outer circumference of the case. In this way, as shown in FIG.
Since the set distance changes depending on the vertical position of, the position of the marker 32a serves as a display unit that simultaneously displays the set distance.

9 and 10 are sectional views of a distance setting type photoelectric switch according to a third embodiment of the present invention. In this embodiment, a thin colored thin plate is arranged as the display means instead of the worm gear of the second embodiment, and the same parts as those in the second embodiment are designated by the same reference numerals and detailed description thereof will be omitted.
In this embodiment, the frame 41 has the PSD 2 at one end thereof.
8 and the other has a female thread 41a. The frame 41 is held movably up and down by rotating the adjusting screw 30 as in the first embodiment. Then, a colored thin thin plate 42 is attached to the frame 4 with its upper portion curved. When the frame 41 is moved up and down by the adjusting screw 30 as shown in FIGS. 9 and 10, the bending position of the thin plate 42 changes accordingly.
Therefore, as shown in FIGS. 9 and 10, the set distance can be displayed by the position of the thin plate 42 which can be recognized from the outside of the case 21.

If the substrate on which the PSD 28 is mounted is a flexible substrate, the thin plate 42 can be shared with the flexible substrate. In this case, the effect that the structure can be simplified is also obtained.

[0022]

As described in detail above, according to the invention of claim 1 or 2, the light receiving portion is rotatably held and the worm gear is rotated, so that the angle of the light receiving portion can be adjusted via the cam. It is rotating. For this reason, even if the worm gear rotates to the end, it does not damage the device merely by idling. Further, the lens area can be made larger than that of the case, and the effect of being able to eliminate the fluctuation of the set distance even when the worm gear is rotated to the end is obtained. Further, according to the invention of claim 2, since the cam is provided with the scale, the set distance can be identified from the scale.

Further, in the inventions of claims 3 and 4, the frame having the light receiving element is moved in parallel by the adjusting screw. By providing the display means at the position corresponding to the adjusting screw, the effect that the set distance can be displayed can be obtained. In this case, since the adjusting screw is a multi-rotation type, there is an effect that the set distance can be accurately adjusted.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the configuration of a distance setting type photoelectric switch according to a first embodiment of the present invention.

FIG. 2 is a front view and a cross-sectional view showing a configuration of a cam used in the first embodiment.

FIG. 3 is a sectional view showing a state in which a worm gear of the photoelectric switch according to the first embodiment is rotated.

FIG. 4 is a sectional view showing a state in which a worm gear of the photoelectric switch according to the first embodiment is rotated.

FIG. 5 is a diagram showing a display state of a display window when the worm gear is rotating according to the first embodiment.

FIG. 6 is a graph showing changes in the rotation angle of the worm gear, the angle of the optical axis of the light emitting / receiving unit, and the set distance according to the first embodiment.

7A and 7B are a sectional view and a front view showing a configuration of a distance setting type photoelectric switch according to a second embodiment of the present invention.

FIG. 8 is a sectional view and a front view showing the structure of a distance setting type photoelectric switch according to a second embodiment of the present invention.

9A and 9B are a sectional view and a front view showing a configuration of a distance setting type photoelectric switch according to a third embodiment of the present invention.

FIG. 10 is a sectional view and a front view showing the configuration of a distance setting type photoelectric switch according to a third embodiment of the present invention.

FIG. 11 is a diagram showing an optical system of a general distance setting type photoelectric switch.

[Explanation of symbols]

 1, 21 Case 2, 24 Light emitting part 3, 22 Light emitting element 4, 23 Light emitting lens 6, 27 Light receiving lens 5, 25 Light receiving part 7 Holder 8, 14 Torsion coil spring 10, 28 PSD 11 Contact piece 12 Cam 13 Worm gear 29,41 Frame 29a, 41a Female thread 30 Adjusting screw 31 Pinion gear 32 Arm 32a Marker 42 Thin plate

Claims (4)

[Claims] 1. A holder, which is fixed in a case, has a light projecting element, irradiates a parallel light beam toward a detection region, and a lens and a light receiving element are fixed and rotatably held. A light receiving portion including a worm gear, a worm gear rotatably held in a case, and a gear portion whose one end meshes with the worm gear, and one end of which abuts against a contact piece of the holder and rotates to receive light from the holder. A distance setting type photoelectric switch, comprising: a cam for rotating a shaft. 2. The cam has a scale for displaying a distance on an outer periphery thereof, and the case has an opening portion opened at a position corresponding to the scale portion of the cam. Item 1. A distance setting type photoelectric switch according to item 1. 3. A light projecting section having a light projecting element for irradiating a parallel light beam toward a detection region, and a lens arranged such that the light receiving axes intersect at a constant angle from the light projecting section. And a light receiving portion having a holder to which the lens is fixed, an adjusting screw rotatably held in a case, and a female screw meshing with the adjusting screw, and are vertically movable along the axis by the rotation of the adjusting screw. A frame that is held and holds the light receiving element at one end, a rack formed on the outer periphery of the frame, a pinion gear that meshes with one end of the rack and is rotatably held in a case, and fixed to the pinion gear And a display unit that displays the position of the light receiving unit by the rotation thereof. 4. A light projecting portion having a light projecting element for irradiating a parallel light beam toward a detection region, and a lens arranged such that the light receiving axes intersect at a certain angle from the light projecting portion. And a light receiving portion having a holder to which the lens is fixed, an adjusting screw rotatably held in a case, and a female screw meshing with the adjusting screw, and are vertically movable along the axis by the rotation of the adjusting screw. A display unit comprising a frame which is held and holds the light receiving element at one end, and a thin plate which is connected to the frame at one end and is bent so that the other end is close to the inner surface of the case. Distance setting type photoelectric switch.