JP4312342B2 - Photoelectric switch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photoelectric switch capable of projecting light output from a light emitting unit through a lens and adjusting the position of the lens with respect to the light emitting unit.
[0002]
[Prior art]
Conventionally, a photoelectric switch has been used to detect the presence or absence of an object in a production line of a factory. This photoelectric switch adjusts the distance between the photoelectric switch and the object so that the object is located within the detection area of the photoelectric switch, projects light onto the detection area of the object, and receives feedback light from the object, The presence or absence of an object is determined.
[0003]
In one of such conventional photoelectric switches, a laser diode as a light emitting part is fixed to a cylindrical light emitting part holder having an internal thread formed on the inner peripheral surface so that the detection distance to an object can be adjusted. There is a type in which a lens is fixed to a lens holder in which an external thread is formed on an outer peripheral surface, and a male screw of a lens holder is screwed to an internal thread of a light emitting unit holder. In this photoelectric switch, the position of the lens with respect to the light emitting unit is moved by rotating the lens holder relative to the light emitting unit holder, the spot shape and the spot position of the light projected from the lens are varied, and the object and The spot is adjusted according to the distance from the photoelectric switch.
[0004]
Further, in the above-described conventional photoelectric switch, a nut-like lock member having a female thread portion similar to the light emitting portion holder formed on the inner peripheral surface is screwed into the female thread portion of the lens holder, and the lock portion is tightened. The position of the lens with respect to the light emitting part is locked by bringing the end face of the lock part into contact with the end face of the light projecting part holder.
[0005]
[Problems to be solved by the invention]
In the above-described conventional photoelectric switch, the lens holder is moved by the screw mechanism, so that the lens is displaced with respect to the light emitting portion due to the backlash of the screw mechanism due to the clearance between the male screw and the female screw, and the projected light. The spot shape on the object changes or the spot position changes.
[0006]
Further, since the lens holder is rotated by the screw mechanism, the lens itself fixed to the lens holder also rotates, and the lens holder rotates when the center of the lens is deviated from the optical axis of the light output from the light emitting unit. Accordingly, the center of the lens rotates around the optical axis, and in this case, the spot shape on the object of the projected light changes or the spot position changes.
[0007]
Furthermore, if the lens holder is tightened with the nut-shaped lock member to lock the lens position, the position of the lens moves by the backlash of the screw mechanism before and after the locking operation, and the position of the lens from the adjusted position. As a result, the spot shape on the object of the projected light changes or the spot position changes.
[0008]
In order to solve the above-mentioned problem, it is conceivable that the tolerance of lens displacement with respect to the optical axis can be relaxed by increasing the distance between the light emitting unit and the lens. Therefore, the amount of light incident on the lens surface with respect to the amount of light emitted from the light emitting unit is reduced, and the light incident efficiency into the lens is reduced. In addition, if the area of the lens is increased in order to increase the light incident efficiency to the lens, the light projecting portion becomes larger.
[0009]
An object of the present invention is to provide a photoelectric switch capable of moving a lens in the optical axis direction with high accuracy with respect to the light emitting unit while maintaining the center position of the lens with respect to the optical axis of light output from the light emitting unit with high accuracy. Is to provide.
[0010]
[Means for Solving the Problems and Effects of the Invention]
(1) photoelectric switch according to the first invention the first invention, the light receives the reflected light as well as projecting light, a photoelectric switch for detecting the object based on the received reflected light, the apparatus main body A light emitting unit that outputs light, a lens that receives light output from the light emitting unit, a lens holding unit that holds the lens, and a device that is fixed to the device body and does not rotate with respect to the device body A support portion that supports the lens holding portion in a state that allows the light output from the light emitting portion to be slidable in the optical axis direction, and is rotatable to the apparatus main body and protrudes outward from the apparatus main body along the optical axis direction. A rotating unit having an inner peripheral surface that is screwed with the lens holding unit, an urging unit that urges the lens holding unit in the optical axis direction of the light output from the light emitting unit, and And a lock portion for locking rotation Is.
[0011]
In the photoelectric switch according to the present invention, the light emitting unit that outputs light is fixed to the apparatus main body, and the lens holding unit that holds the lens that receives the light output from the light emitting unit is provided by the support unit fixed to the apparatus main body. It is supported so that it can slide in the optical axis direction of the light output from the light emitting unit without rotating with respect to the main body. Therefore, the lens holding portion, that is, the lens is lighted with respect to the light emitting portion in a state in which the support portion functions as a slide bearing with respect to the lens holding portion and there is no large play like a screw mechanism in the direction perpendicular to the optical axis. The lens can be slid in the axial direction, and the lens can be moved with high accuracy with respect to the light emitting unit.
[0012]
In addition, since the rotating unit having an inner peripheral surface screwed with the lens holding unit is supported by the apparatus main body in a state that it can rotate to the apparatus main body and protrudes outward from the apparatus main body along the optical axis direction , By rotating the rotating part, the lens holding part screwed into the rotating part can be moved in the optical axis direction. At this time, the rotating unit rotates and the lens holding unit slides according to the rotation of the rotating unit, so that the lens holding unit, that is, the lens moves in the optical axis direction without rotating. Therefore, the lens can be moved in a state in which the center position of the lens with respect to the optical axis direction of the light output from the light emitting unit is held at the position adjusted with high accuracy at the time of assembly.
[0013]
As a result, it is possible to move the lens with high accuracy in the optical axis direction with respect to the light emitting unit while maintaining the center position of the lens with respect to the optical axis of the light output from the light emitting unit with high accuracy.
In addition, since the lens holding portion is biased in the optical axis direction of the light output from the light emitting portion, it is possible to eliminate backlash in the optical axis direction at the screwing portion between the lens holding portion and the rotating portion, and to increase the height. It can be moved by sliding in the optical axis direction with high accuracy.
[0016]
(2) The photoelectric switch according to the second aspect the second invention, in the configuration of the photoelectric switch according to the first invention, the rotation section, a plurality of engaging portions formed in the rotation direction of the rotating part And the locking part is interposed between the adjacent locking parts of the plurality of locking parts by moving in the optical axis direction of the light output from the light emitting part or rotating around the direction intersecting the optical axis direction. also the in which you lock the rotation of the rotating part is.
[0017]
In this case, the lock unit is moved in the optical axis direction of the light output from the light emitting unit, or rotated about the direction intersecting the optical axis direction as a rotation center, so that a plurality of engagements formed along the rotation direction of the rotary unit are formed. A lock part is interposed between the adjacent locking parts among the stop parts, and the rotation of the rotating part is locked. Thus, since the lock portion is interposed along the optical axis direction of the light, that is, along the rotation center axis of the rotation portion, the rotation portion can be locked without substantially rotating the rotation portion. In addition, even if the lock part comes into contact with the engaging part when the lock part is interposed between the engaging parts, the rotating part can be slightly rotated to release the stress from the lock part, Unnecessary stress is not applied to the lens holding part and the lens from the part through the rotating part. As a result, the lens can be locked in a state in which the lens is adjusted with high accuracy without substantially changing the position of the lens with respect to the light emitting unit before and after the locking operation.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter will be described the present invention engaging Ru photoelectric switch. This photoelectric switch has a light emitting means for generating light and a light receiving means for receiving the light and outputting a light reception signal corresponding to the amount of light received, and projects the light generated by the light emitting means to the detection area and from the detection area. Is detected by the light receiving means to detect the presence or absence of an object in the detection region.
[0019]
FIG. 1 is an external perspective view of a photoelectric switch according to an embodiment of the present invention viewed from one direction, and FIG. 2 is an external perspective view of the photoelectric switch of FIG. 1 viewed from another direction.
[0020]
In the photoelectric switch 1 of FIGS. 1 and 2, a light projecting unit 2 serving as a light emitting unit that projects light is provided on a case 11 serving as a housing, and light is projected from the light projecting unit 2 next to the light projecting unit 2. A light receiving unit 3 is provided as a light receiving unit that receives reflected light reflected by an object that receives the received light. The photoelectric switch 1 receives the light incident on the light receiving unit 3 among the light reflected by the object that receives the light projected from the light projecting unit 2, detects the presence or absence of the object based on the amount of received light, and outputs the detection result To do.
[0021]
A display unit 4 is provided on the side opposite to the light emitting / receiving surface where the light projecting unit 2 and the light receiving unit 3 of the case 11 of the photoelectric switch 1 are provided, that is, on the back surface of the light receiving / emitting surface. The display unit 4 is provided with an LED (light emitting diode) or the like, and displays the amount of light received by the light receiving unit 3 or the like.
[0022]
Further, the light projecting unit 2 rotates the lens barrel cover 20 in the direction of the arrow in the drawing, thereby changing the position of the light projecting lens with respect to the laser diode serving as the internal light emitting unit as described below. By changing the distance, the shape and position of the spot on the object can be adjusted.
[0023]
FIG. 3 is a partial cross-sectional view mainly showing a portion of the light projecting unit 2 of the photoelectric switch shown in FIG. 1, and FIG. 4 is a partial cross-sectional view of the light projecting unit shown in FIG.
[0024]
As shown in FIGS. 3 and 4, the laser holder 12 is integrally formed on the side surface of the case 11 provided substantially perpendicular to the light emitting / receiving surface. A through hole is formed at the center of the laser holder 12, and a laser diode 13 serving as a light emitting unit is fitted into the through hole, and the laser diode 13 is fixed to the laser holder 12.
[0025]
The laser holder 12 is fitted with a guide portion 14 serving as a support portion for slidably supporting a lens holder 15 serving as a lens holding portion. A light projection lens 16 is fixed inside the lens holder 15. A lens holder 15 is inserted into the cylindrical guide portion 14 in a highly accurate fitting state (for example, the clearance between the inner diameter of the guide portion 14 and the outer diameter of the lens holder 15 is about 10 to 20 μm). The guide portion 14 functions as a slide bearing, and the lens holder 15 is held in a state in which the lens holder 15 can be smoothly slid along the optical axis direction of the light output from the laser diode 13.
[0026]
Thus, the case 11, the laser holder 12, and the guide part 14 become a fixed part (apparatus main body). The case 11, the laser holder 12, and the guide part 14 may be formed integrally with all or part of them.
[0027]
A coil spring 17 serving as an urging means is interposed between the laser holder 12 and the lens holder 15, and the lens holder 15 is separated from the laser diode 13 along the optical axis direction by the coil spring 17. Is biased in the direction.
[0028]
A male screw is formed on the outer peripheral surface of the lens holder 15 on the light projecting lens 16 side, a female screw that engages with the male screw of the lens holder 15 is formed on the inner peripheral surface of the lens barrel portion 18, and the lens barrel portion 18 is the lens holder. 15 is screwed. A lens barrel cover 20 is fitted on the outer peripheral surface of the lens barrel portion 18. An antireflection plate 21 for preventing regular reflection is fixed near one end of the inner peripheral portion of the lens barrel portion 18. A lens barrel holding portion 19 is fitted to the other end portion of the inner peripheral portion of the lens barrel portion 18.
[0029]
The case 11 is interposed between the end of the lens barrel cover 20 on the laser diode 13 side and the end of the lens barrel holding portion 19 on the light projecting lens 16 side, and the lens barrel cover 20, the lens barrel portion 18, and The lens barrel holding portion 19 is supported so as to be rotatable with respect to the case 11.
[0030]
Therefore, by rotating the lens barrel cover 20, the lens barrel cover 20, the lens barrel portion 18, the lens barrel holding portion 19 and the antireflection plate 21 are rotated together, and the lens barrel cover 20, the lens barrel portion 18 and the mirror are rotated. The cylinder holding part 19 becomes a rotating part. The lens barrel cover 20, the lens barrel portion 18, and the lens barrel holding portion 19 may be formed integrally with all or a part thereof.
[0031]
A plurality of locking portions 25 are formed in a gear shape at a constant pitch along the rotation direction of the lens barrel holding portion 19 on the outer peripheral surface of the lens barrel holding portion 19, and each locking portion 25 has a substantially triangular cross section. It has a raised shape, and a substantially inverted triangular valley is formed between adjacent locking portions 25. The shape and number of the locking portions 25 are not particularly limited to the illustrated example, and may be other shapes and numbers.
[0032]
A multi-stage columnar lock portion 22 is disposed on the side of the lens barrel holding portion 19. Both ends of the lock portion 22 are supported by the case 11 and the upper lid 26 fixed to the case 11, and the lock portion 22 is rotatable. Supported by the state. Slots 24 are provided at both ends of the lock part 22, and a tip of a screwdriver is inserted into the slot 24 to rotate the lock part 22 around the direction of the arrow in the figure, that is, the direction orthogonal to the optical axis direction. Can do.
[0033]
In addition, two convex portions 23 having a substantially triangular cross section are formed in the middle portion of the lock portion 22 so as to protrude in one direction (downward in FIG. 3). The state shown in FIGS. 3 and 4 shows a state in which the lens barrel holding part 19, that is, the rotating part is not locked by the lock part 22. The shape and number of the convex portions 23 are not particularly limited to the illustrated example, and may be other shapes and numbers.
[0034]
In the light projecting portion 2 of the photoelectric switch 1 configured as described above, the laser diode 13 is fixed to the laser holder 12, the guide portion 14 is fixed to the laser holder 12, and the light output from the laser diode 13 is received. A lens holder 15 that holds the optical lens 16 is supported by the guide portion 14 so as to be slidable in the optical axis direction of the light output from the laser diode 13.
[0035]
At this time, since the lens holder 15 is inserted into the guide portion 14 with a high-precision fitting state, the lens holder 15, that is, the light projecting lens 16 is placed on the laser diode 13 with no backlash in a direction perpendicular to the optical axis direction. Can be slid in the direction of the optical axis.
[0036]
In addition, since the lens barrel portion 18 that is screwed into the lens holder 15 is supported by the case 11 so as to be rotatable around the optical axis direction together with the lens barrel holding portion 19 and the lens barrel cover 20, the lens barrel cover 20 By rotating the lens holder 15, it is possible to move the lens holder 15 screwed into the lens barrel portion 18 in the optical axis direction.
[0037]
At this time, the lens barrel portion 18 rotates and the lens holder 15 slides according to the rotation of the lens barrel portion 18, so that the lens holder 15, that is, the light projecting lens 16 moves in the optical axis direction without rotating. Therefore, the light projection lens 16 can be moved in a state where the center position of the light projection lens 16 with respect to the optical axis direction of the light output from the laser diode 13 is held at a position adjusted with high accuracy at the time of assembly.
[0038]
As a result, the projection lens 16 is moved with high accuracy in the optical axis direction relative to the laser diode 13 while maintaining the center position of the projection lens 16 with respect to the optical axis of the light output from the laser diode 13 with high accuracy. be able to.
[0039]
Further, since the lens holder 15 is urged by the coil spring 17 in the optical axis direction of the light output from the laser diode 13, the play in the optical axis direction at the threaded portion between the lens holder 15 and the lens barrel portion 18 is prevented. It can be eliminated, and can be moved by sliding in the optical axis direction with higher accuracy. The biasing means is not particularly limited to the above-described coil spring, and other springs such as a leaf spring and a disc spring or an elastic member such as elastic rubber may be used.
[0040]
FIG. 5 is a partial cross-sectional view mainly showing a portion of the light projecting portion 2 of the photoelectric switch shown in FIG. 1 in a locked state in which the lens barrel holding portion 19 is locked by the lock portion 22. FIG. It is the partial cross section figure which looked at the light projection section which is shown from back.
[0041]
When the user inserts the screwdriver into the slot 24 and rotates the lock portion 22 by 90 degrees, the convex portion 23 of the lock portion 22 becomes the locking portion of the lens barrel holding portion 19 as shown in FIGS. 25. Even if the lens barrel cover 20 is to be rotated in this state, the locking portion 25 of the lens barrel holding portion 19 comes into contact with the convex portion 23 of the lock portion 22, so that the lens barrel cover 20 does not rotate and the lock portion 22 The tube holding part 19 is locked, and the position of the light projection lens 16 with respect to the laser diode 13 is fixed.
[0042]
Here, in the locked state shown in FIGS. 5 and 6, a predetermined clearance can be formed in the rotation direction of the lens barrel holding portion 19 between the convex portion 23 of the lock portion 22 and the locking portion 25 of the lens barrel holding portion 19. Thus, the cross-sectional shape of both is set. Therefore, when the convex part 23 is interposed just in the middle between the latching parts 25, the convex part 23 and the latching part 25 do not contact. As a result, unnecessary stress is not transmitted from the lock portion 22 to the light projecting lens 16 through the lens barrel holding portion 19, and the lens barrel holding portion 19 does not rotate. The position of the projection lens 16 with respect to 13 does not change at all, and the projection lens 16 can be locked as it is with the projection lens 16 being adjusted with high accuracy.
[0043]
In addition, when the position of the locking part 25 is slightly shifted and the convex part 23 is interposed between the locking part 25 while the convex part 23 and the locking part 25 are in contact, the lens barrel holding part 19 is Since there is no member that restricts the rotation other than the lock portion 22, unnecessary stress from the convex portion 23 can be released by slightly rotating the lens barrel holding portion 19. Therefore, also in this case, unnecessary stress is not transmitted from the lock portion 22 to the light projecting lens 16 via the lens barrel holding portion 19. In this case, the lens barrel holding portion 19 rotates slightly, but the amount of movement in the optical axis direction with respect to the amount of rotation of the lens barrel holding portion 19 is very small. Therefore, the light projection lens 16 for the laser diode 13 before and after the locking operation. The projection lens 16 can be locked in a state in which the position of the projection lens 16 is adjusted with high accuracy.
[0044]
Thus, in this embodiment, the focal length can be adjusted while maintaining the center position of the light projection lens 16 with respect to the optical axis of the light output from the laser diode 13 with high accuracy. Further, since the position of the light projection lens 16 with respect to the laser diode 13 hardly changes before and after the lock operation after the focus adjustment, the light projection lens 16 can be locked without changing the spot. Further, since the light projecting lens 16 is locked after the locking, the spot does not change during the detection of the object. Accordingly, the focal length adjustment operation, the lock operation, and the detection operation are facilitated, and the presence or absence of a desired object can be easily detected in a short time.
[0045]
In the present embodiment, the lock portion 22 that rotates around the direction orthogonal to the optical axis direction is used as the lock mechanism. However, the lock portion 22 moves linearly along the optical axis direction and moves between the locking portions 25. You may use the lock part interposed in. Moreover, although the latching | locking part 25 was provided in the outer peripheral surface of the lens-barrel holding | maintenance part 19, the locking | rocking part is formed in the inner peripheral surface of the lens-barrel holding | maintenance part 19, and the locking part interposed between this latching | locking part It may be used.
[0046]
The photoelectric switch to which the present invention is applied is not particularly limited to the above-described photoelectric switch as long as it projects light, and is a reflection type or transmission type, a built-in amplifier type or an amplifier separation type, and a projection optical system. Can be applied to any photoelectric switch such as a separation optical system in which a light receiving optical system is separated or a coaxial optical system using a beam splitter, etc., and a photoelectric sensor for measuring a distance to an object, etc. The present invention can be similarly applied to other optical devices such as an optical displacement meter, a color discrimination sensor for identifying color shading, and the like, and the same effect can be obtained. Further, although a laser diode is used as the light emitting unit, an LED or the like may be used.
[Brief description of the drawings]
FIG. 1 is an external perspective view of a photoelectric switch according to an embodiment of the present invention viewed from one direction.
2 is an external perspective view of the photoelectric switch of FIG. 1 as viewed from the other direction.
3 is a partial cross-sectional view mainly showing a light projecting portion of the photoelectric switch shown in FIG. 1;
4 is a partial cross-sectional view of the light projecting unit shown in FIG. 3 as viewed from the back.
5 is a partial cross-sectional view showing mainly a light projecting portion of the photoelectric switch shown in FIG. 1 in a locked state in which the lens barrel holding portion is locked by the lock portion. FIG.
6 is a partial cross-sectional view of the light projecting unit shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photoelectric switch 2 Light projection part 3 Light reception part 4 Display part 11 Case 12 Laser holder 13 Laser diode 14 Guide part 15 Lens holder 16 Light projection lens 17 Coil spring 18 Lens barrel part 19 Lens barrel holding part 20 Lens barrel cover 21 Antireflection Plate 22 Locking portion 23 Convex portion 24 Slot 25 Locking portion 26 Upper lid

Claims (2)

A photoelectric switch that projects light and receives reflected light, and detects an object based on the received reflected light ,
A light emitting unit that is fixed to the apparatus body and outputs light;
A lens that receives light output from the light emitting unit;
A lens holding part for holding the lens;
A support unit that is fixed to the apparatus main body and supports the lens holding unit in a state that it can slide in the optical axis direction of the light output from the light emitting unit without rotating with respect to the apparatus main body;
A rotating part that is rotatable to the apparatus main body and is supported in a state of protruding outward from the apparatus main body along the optical axis direction, and having an inner peripheral surface that is screwed with the lens holding part ;
An urging means for urging the lens holding unit in an optical axis direction of light output from the light emitting unit;
A photoelectric switch comprising: a lock portion that locks rotation of the rotation portion . The rotating part includes a plurality of locking parts formed along the rotating direction of the rotating part,
The locking part moves between the adjacent locking parts of the plurality of locking parts by moving in the optical axis direction of the light output from the light emitting part or rotating around the direction intersecting the optical axis direction. the photoelectric switch according to claim 1 Symbol mounting features a lock to Turkey the rotation of the rotating portion is interposed.

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