JP2854605B2 - Photoelectric sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric sensor having a light-collecting optical system and a photoelectric conversion element.

[Prior Art] A photoelectric sensor is used for automation of various machines, detection of a conveyed object by a conveyor line, detection of approach of a person at an automatic door or the like since it can detect a person or an object without contact.

And the light emitter and light receiver of such a photoelectric sensor are:
In each case, a convex lens is fixed by drilling a circular hole in the wall of the box-shaped case, and a light emitting element such as a light emitting diode or a photoelectric element such as a light receiving element such as a phototransistor is provided at the focal point. Lighting drive circuit, signal amplifier circuit, operation indicator lamp, variable resistor, and other parts are fixed to the inner wall of the case so as not to obstruct the path of the light reaching, and the parts are electrically connected to each other. And the output terminal are connected to a wire cord and led out of the case, and the lid is closed.

FIG. 13 is a view showing such a conventional photoelectric sensor. In the figure, A is a converging convex lens provided on the front surface of a casing B, and 61 is a photoelectric converging lens set at a converging point position of the convex lens A. A conversion element, 62 is a wiring board, 63 is various electronic components provided on the wiring board 62, and 64 is an operation indicator light.

Reference numeral 65 denotes a back panel of the casing B, and C denotes a wiring between the operation indicator light and the wiring board 62. Then, for mounting to a machine or the like, a bracket or the like is used and fixed with screws or the like.

[Problems to be Solved by the Invention] Recently, the demand for miniaturization of photoelectric sensors has been increasing from users, and miniaturization has been performed year by year. However, there are two problems that hinder miniaturization in structure.

The first problem is that a driver, tweezers,
The work must be performed by inserting a tool such as a soldering iron, and the smaller the case is, the more difficult the work becomes.

Thus, the miniaturization of the photoelectric sensor and the efficiency of the assembling work are mutually contradictory.

A second problem is that since a convex lens is used for the condensing optical system, a considerably large conical space is required in the path of light reaching the photoelectric conversion element. In other words, in order to improve the performance of the photoelectric sensor, it is desirable to increase the aperture of the lens to increase the amount of incident light and to appropriately lengthen the focal length of the lens to reduce the influence of disturbance light.

Therefore, a lens having a large aperture and a long focal length is required, so that a large conical space is required.

As described above, miniaturization of the photoelectric sensor and improvement of the optical characteristics are mutually contradictory.

Further, one of the drawbacks of the conventional photoelectric sensor is that handling is inconvenient. In other words, since the device is large in size and takes up space even when attached to a machine or the like, it easily touches a person or an object, and the optical axis shifts, which causes a malfunction. In addition, there is a problem that it is difficult to clean even if dust or oil adheres.

In recent years, for example, in order to prevent malfunction due to the influence of external electromagnetic radiation noise generated by opening and closing a magnet switch when starting an inverter motor, the photoelectric conversion element itself is plated with metal vapor deposition. The disadvantage is that the transmission is reduced.

The present invention has been made in view of the above-mentioned problems, and solves the above-mentioned problems, has good assembling workability, good optical characteristics, and is hardly affected by external electromagnetic radiation noise, and is small and easy to handle. It is an object to provide a photoelectric sensor.

[Means for Solving the Problems] The photoelectric sensor according to this application is formed of a transparent body, the front surface (objective surface) forms a circular flat surface, and the rear surface (the circuit block surface) forms a circular convex surface. An optical element having a substantially half-moon shape, a circuit block disposed on the rear surface of the optical element, a cylindrical casing housing the optical element and the circuit block and opening one side, and fitted into the casing opening And a lock nut screwed onto a circular outer peripheral surface of the casing. A first concave portion having a diameter of about 1/3 of the front surface is formed at the center of the front surface of the optical body. A second concave portion having a convex bottom surface or a Fresnel bottom surface facing the first concave portion and having a diameter slightly smaller than that of the first concave portion is formed in the center of the rear surface side to form a condensing lens facing the photoelectric element. With The concave bottom surface of the first concave portion is mirror-finished by vacuum deposition plating means to form a second reflecting portion, and the portion of the optical body except the second concave portion on the rear surface is mirror-finished by vacuum deposition plating means. (1) forming a reflection portion, and further, a skirt portion on the periphery of the rear surface of the optical body;
An indicator light condensing lens portion for transmitting the light flux of the operation indicator light to the front side of the optical body is formed at an appropriate position of the reflecting portion, and the circuit block includes a photoelectric conversion element and an operation indicator light on the front surface. An electronic component is mounted on both front and rear surfaces, and the terminal is formed of a circular circuit board abutting on the end surface of the skirt portion.

Further, another photoelectric sensor according to the present application is formed of a transparent body, and has a front surface (object surface) having a circular flat surface and a rear surface (corresponding to a circuit block surface) having a circular convex shape, and having an almost half-moon cross section. A body, a circuit block disposed on the rear surface of the optical body, a cylindrical metal casing that accommodates the optical body and the circuit block and opens one side, and a transparent protector that fits into the casing opening. In the center of the front surface of the optical body, approximately 3
A first concave portion having a diameter of about one-half the diameter of the first concave portion;
A second concave portion having a convex bottom surface or a Fresnel bottom surface slightly smaller in diameter than the concave portion is formed as a condensing lens facing the photoelectric element, while the concave spherical bottom surface in the first concave portion is made a mirror surface by vacuum evaporation plating means. A second reflecting portion is formed by removing the second concave portion from the rear surface of the optical body to form a mirror surface by vacuum evaporation plating means to form a first reflecting portion; Part, also the first
An indicator light condensing lens portion for transmitting the light flux of the operation indicator light to the front side of the optical body is formed at an appropriate position of the reflecting portion, and the circuit block includes a photoelectric conversion element and an operation indicator light on the front surface. Electronic components are mounted on both front and rear surfaces, and the periphery thereof is formed of a circular circuit board whose peripheral edge is in contact with the end surface of the skirt portion. Further, the first and second recesses block electromagnetic radiation noise from outside. A first shield and a second shield are provided, and these are respectively connected to the ground terminal of the power supply. The first shield is formed of a circular metal plate that fits into the opening of the first recess, and the second shield is formed of a metal cylinder that fits in the second recess.

[Operation] The signal light such as infrared light or red light incident through the transparent protector is reflected first by the first reflecting portion of the optical body, reaches the second reflecting portion, and is reflected by the second time. The light passes through the condenser lens and is received by the photoelectric conversion element located at the focal point of the condenser lens.

The signal light received by the photoelectric conversion element is converted into an electric signal and output.

Then, since the change in the light quantity of the incident signal light is immediately captured as an electric signal, it is possible to accurately detect an object in the optical path in front of the photoelectric sensor. As described above, the light passage path has been described in the case of the light receiver, but the reverse is true in the case of the light projector.

The optical body has a plurality of reflectors, so that the optical path from the incident on the photoelectric sensor to the focal point of the photoelectric conversion element can be housed in a thin plate-like optical body in a so-called folded state. Thus, a compact photoelectric sensor can be obtained as a whole.

In addition, when a metal casing and a shield are provided, it is particularly effective in an environment in which external electromagnetic radiation noise adversely affects the detection function.

Embodiment An embodiment of the present invention will be described with reference to the drawings. First
FIG. 4 to FIG. 4 are diagrams showing an embodiment of the invention according to claims 1 to 3 of this application.

FIG. 1 is a longitudinal sectional view of the photoelectric sensor, FIG.
FIG. 3 is a side view of the same, and FIG. 4 is an explanatory view of an optical body.
(A) is a side view, (b) is a front view, (c) of FIG.
FIG. 2B is a cross-sectional view taken along the line cc in FIG. 2B, and FIG.

In the figure, reference numeral 1 denotes an optical body formed of a transparent resin material;
Is a casing made of resin material and forms a cylindrical body with one opening.A screw part 2a is formed on the outer peripheral surface, and an annular stopper 2b is formed integrally with the casing at the outer peripheral end on the object side. Have been. The stopper 2b has a groove on its inner peripheral surface for fitting an engaging claw of a transparent protector described later.

Reference numeral 3 denotes a disk-shaped protector fitted and mounted in the opening of the casing 2 and is formed of a transparent resin material, and has an engaging claw 3a at an edge thereof so as to fit into the groove of the stopper 2b. It has become.

Reference numeral 4 denotes a circuit board installed in the casing 2 so as to face the rear surface of the optical body 1. The photoelectric conversion element 4 a and the operation indicator light 4 b are provided on the surface facing the optical body 1, and the electronic components are provided on the back surface. 4c, respectively, and these circuit boards 4,
The photoelectric conversion element 4a and the operation indicator light 4b constitute a circuit block.

Reference numeral 5 denotes a resin material such as epoxy injected between the circuit board 4 and the bottom surface of the casing 2 as a measure against water, vibration and moisture of the circuit block.

Reference numeral 6 denotes a lock nut screwed into the screw portion 2a and a washer 7
The mounting panel 8 is fixedly held between the mounting panel 8 and the stopper 2b via the. Reference numeral 9 denotes an annular rubber packing inserted between the protector 3 and the casing 2, and reference numeral 10 denotes input / output lead wires connected to the circuit board 4.

 Next, the configuration of the optical body 1 will be described with reference to FIG.

FIGS. 4 (a), (b), (c), and (d) are a side view, a front view, a longitudinal sectional view, and a rear view of the optical body, respectively.

In the figure, reference numeral 1 denotes an optical body for a photoelectric sensor integrally formed of a transparent resin material and has a semicircular shape having a diameter of 20 mm. Reference numeral 21 denotes a front surface, that is, an object surface of the optical body 1 facing the detection target object, and is formed in a circular plane. (Diameter 18 mm) When the optical body 1 is used for detecting an object at a position closer than about 1 m, the objective surface is preferably formed as a gentle convex surface.

Reference numeral 31 denotes a rear surface, that is, a surface facing a photoelectric conversion element, which is a surface facing a circuit block, and is formed in a circular convex shape having a diameter of 18 mm (R = 13.4 mm and an aspheric surface).

As shown in FIGS. 4 (b) and 4 (c), the central part of the front surface (objective surface) 21 has a concave spherical bottom surface (R) having a diameter (7 mm) slightly more than one third of the front surface (objective surface) 21. = 7.7mm and aspheric)
Is formed. This first recess 41
A mirror surface is formed on the concave spherical bottom surface by vacuum evaporation plating to constitute a second reflecting portion 41a. Reference numeral 51 denotes a second concave portion formed at the center of the rear surface 31 (the surface facing the circuit block) so as to face the first concave portion 41, and the bottom surface portion has a diameter slightly smaller than the concave bottom surface of the first concave portion 41 ( 1.5: 1) convex bottom (R =
8.5 mm and a spherical surface) to form the condenser lens portion 51a.

Then, the photoelectric conversion element 4a of the circuit block 4 faces or fits in the second concave portion 51. 1a is a skirt portion (approximately 3 mm in height) formed over the entire periphery of the edge of the rear surface 31, 1b
Indicates that the luminous flux of the operation indicator light 4b is directed in the direction of the circular
Operation indicator light on rear face 31 to radiate through 21
A convex portion as an operation indicator light condensing lens portion formed at a position facing 4b. The surface of the convex portion 1b is a convex surface,
Alternatively, if it is formed on the Fresnel surface, the irradiation light becomes parallel light, which makes it easy to view from a long distance.

Reference numeral 1c denotes a first reflecting portion formed of a mirror surface formed on the convex spherical surface (excluding the second concave portion 51) of the rear surface 31 by means such as vacuum deposition plating.

In addition, each component other than the optical body 1 is formed in a size corresponding to the above-mentioned size of the optical body 1. In this embodiment (FIG. 8), the outer diameter of the photoelectric sensor is 20 mm and the thickness is about 14 mm. ing.

 Next, the operation of this embodiment will be described.

The signal light incident from the front surface 21 side of the optical body 1 through the protector 3 is reflected by the first reflecting portion 1c to reach the second reflecting portion 41a, passes through the condenser lens portion 51 by the second reflection, and performs photoelectric conversion. The light is condensed at the position of the element 4a, converted into an electric signal, and output.

Since the change in the amount of incident light is immediately detected as an electric signal, it is possible to accurately detect an object on the front surface of the sensor, that is, on the optical path toward the front surface 21 of the protector 3 or the optical body 1. The optical body 1 has a first reflecting portion and a second reflecting portion, so that the optical path from the circular objective surface of the lens A to the focal point of the photoelectric conversion element 61 as shown in the conventional example of FIG. It can be stored in the thin optical member 1 in a folded state. Light from the light emitting diode as the operation indicator light 4b is emitted toward the front surface 21 of the optical body 1 via the convex portion 1b as the indicator light condensing lens.

Most of the electromagnetic radiation noise from the outside is shielded by the metal film formed on the first reflection portion 1c and the second reflection portion 41a, and the accurate operation of the electronic component 4c on the circuit board 4 is ensured. In this way, the first reflection unit 1c and the second reflection unit 41a have a function of shielding electromagnetic radiation noise. The metal coating is electrically connected to the ground side of the power supply, but is not shown.

Next, an embodiment of the invention according to claim 4 will be described with reference to FIGS. 5 to 7.

The same parts as those in the above-described embodiment are denoted by the same reference numerals, and duplicate description will be omitted.

FIG. 5 is a longitudinal sectional view of the photoelectric sensor, FIG. 6 is a front view,
FIG. 7 is a side view.

This embodiment is completely the same as the above-described embodiment except that the configurations of the casing 2 and the protector 3 are slightly different.

That is, in this embodiment, the screw portion 2a is formed on the entire peripheral surface of the casing 2, and the stopper 2b in the above-described embodiment is not provided.

On the other hand, the protector 3 has a shallow cylindrical shape and a bottom surface portion facing the front surface 21 of the optical body 1. An inner screw for screwing to the screw portion 2a (outer screw) is provided on a portion of the protector 3 having no peripheral wall. Are formed. Since the mounted panel 8 is sandwiched between the peripheral wall end of the protector 3 and the lock nut 6 via the washer 7, the peripheral wall end of the protector 3 constitutes a stopper portion. Can be.

The operation and effect of this embodiment are the same as those of the above-described first embodiment, but in this embodiment, the assembling of the protector 3 to the casing 2 becomes easier than in the above-mentioned embodiment.

Next, an embodiment of the invention according to claims 5 to 8 will be described with reference to FIGS. 8 to 12.

8 is a longitudinal sectional view of the photoelectric sensor according to this embodiment, FIG. 9 is a front view thereof, FIG. 10 is a side view thereof, FIG. 11 is a rear view thereof, and FIG. is there. The same portions as those in the above-described embodiment are denoted by the same reference numerals, and redundant description will be omitted.

In the figure, reference numeral 2 denotes a cylindrical casing having one opening, which is formed of a metal material. Reference numeral 3 denotes a protector made of a transparent material for cutting visible light, and a display light transmitting portion 3b is fitted at a position facing the convex portion 1b of the optical body 1.

41b is a first shield fitted into the opening end of the first concave portion 41 of the optical body 1, and 51b is a second shield similarly fitted into the second concave portion of the optical body 1 and is formed of a metal material. I have. Twelfth
As shown in the figure, the first shielding body 41b has a disk shape, and the second shielding body 51b has a cylindrical shape and includes a belonging shielding plate 51c having a through hole 51c1 inside the cylindrical body. This through hole 51c1 serves as a light passage. The other configuration is not different from the above-described embodiment.

In this embodiment, the circuit block is a metal casing 2
Shielded against electromagnetic radiation noise from the rear and side directions, and the first shield 41b against the front.
However, the second shield 51b effectively shields electromagnetic radiation noise from the front obliquely. Therefore, the photoelectric sensor according to this embodiment is suitable for incorporation into various devices used in factories or the like where electromagnetic radiation noise is full.

[Effects of the Invention] As described above, the photoelectric sensor according to the present application eliminates the need for a complicated manual operation such as inserting a tool into a narrow inside of a case and performing an assembling operation as in the related art, and eliminates the need for automatic component mounting. It can be mounted on mass production processes using machines and automatic assembling machines, etc., and significant cost reduction is possible.

In addition, since a conical space necessary for the light path is folded and contained inside itself by a half-moon shaped optical body, the shape is extremely thin and small. (For example, compared to the prior art, the thickness is about one third or less.) Therefore, when installing in a factory, office, store, home, etc., even if it is directly mounted on a wall surface or the like, the mounting work is not spoiled. Is also easy.

In addition, both the projector and the light receiver are small in size, but the aperture of the optical system is large and the focal length is long, so the amount of light incident on the light receiver increases, sensitivity is improved, and the influence of disturbance light is small, and this synergistic effect is achieved. Therefore, in the case of the transmission type, the facing distance between the light emitter and the light receiver becomes extremely long, and similarly, in the case of the reflection type, the detection interval distance between the photoelectric sensor and the target object becomes extremely long, and the detection range of the target object is wide. Become.

Furthermore, the photoelectric sensor according to the present invention can effectively block external electromagnetic radiation noise and perform accurate object detection.

[Brief description of the drawings]

1 to 4 are views showing an embodiment of a photoelectric sensor according to claims 1 to 3 of the present application. FIG. 1 is a longitudinal sectional view of the photoelectric sensor, FIG. 3 is a side view of the same, FIG. 4 is an explanatory view of the optical body, FIG. 3A is a side view of the optical body, FIG. 3B is a front view thereof, and FIG. A cross-sectional view taken along the line cc, FIG.
5 to 7 are views showing an embodiment of the photoelectric sensor according to claim 4 of the present application. FIG. 5 is a longitudinal sectional view, FIG. 6 is a front view thereof, and FIG. Side view, FIGS. 8 to 12
The drawings show an embodiment of the photoelectric sensor according to claims 5 to 8 of the present application, FIG. 8 is a longitudinal sectional view of the photoelectric sensor, FIG. 9 is a front view thereof, FIG. 10 is a side view thereof, FIG. 11 is a rear view, FIG. 12 is an external perspective view of a first shield and a second shield, and FIG. 13 is a longitudinal sectional view showing a conventional technique. In the drawing, 1 ... optical body 2 ... casing 3 ... protector 4 ... circuit block 41 ... first concave portion 41a ... second reflecting portion 51 ... second concave portion 51a ... first reflecting portion 41b ... First shield 51b Second shield

Claims (8)

(57) [Claims] 1. An optical body which is formed of a transparent body and whose front surface (objective surface) has a circular flat surface and whose rear surface (surface facing a circuit block) has a circular convex shape and has a substantially half-moon cross section. A circuit block disposed on the rear surface, a cylindrical casing housing the optical body and the circuit block and opening one side, a transparent protector fitted into the casing opening, and screwed into a circular outer peripheral surface of the casing. A first concave portion having a diameter of about one third of the front surface is formed at the center of the front surface of the optical body; and the first concave portion is formed at the center of the rear surface side of the optical body. Opposite
A second concave portion having a convex bottom surface or a Fresnel bottom surface slightly smaller in diameter than the first concave portion is formed as a condenser lens facing the photoelectric element, and the concave spherical bottom surface in the first concave portion is formed by vacuum evaporation plating means. A second reflecting portion is formed as a mirror surface, a portion of the optical body excluding the second concave portion on the rear surface is formed as a mirror surface by vacuum deposition plating means to form a first reflecting portion; In addition, a skirt portion is formed, and an indicator light condensing lens portion for transmitting the light flux of the operation indicator light to the front side of the optical body is formed at an appropriate portion of the first reflecting portion. A photoelectric conversion element and an operation indicator light, electronic components are mounted on both front and rear sides, and a circular circuit board whose peripheral end abuts directly on the end face of the skirt portion or via a spacer. Support. 2. A casing according to claim 1, wherein a screw portion and a stopper portion are formed on an outer peripheral surface of the casing, and a lock nut is screwed into the casing. The lock nut and the stopper portion sandwich an object to be mounted. The photoelectric sensor according to claim 1. 3. The photoelectric sensor according to claim 1, wherein a resin material is filled between the bottom of the casing and the circuit block. 4. The photoelectric sensor according to claim 1, wherein said transparent protector is screwed into a screw formed on an outer peripheral surface of a casing. 5. An optical body which is formed of a transparent body and whose front surface (objective surface) has a circular flat surface and whose rear surface (surface facing the circuit block) has a circular convex shape and has a substantially half-moon cross section. A circuit block provided on the rear surface, a cylindrical casing housing the optical body and the circuit block and opening one side, and a transparent protector fitted into the casing opening, and a front center of the optical body. A first concave portion having a diameter of about one third of the front surface is formed, and a center of the optical body on the rear surface side is opposed to the first concave portion and has a diameter slightly smaller than the first concave portion. A second concave portion having a convex bottom surface or a Fresnel bottom surface is formed as a condensing lens facing the photoelectric element, while the concave spherical bottom surface in the first concave portion is made a mirror surface by vacuum evaporation plating means to form a second reflecting portion. Of the optical body A portion of the rear surface excluding the second concave portion is mirror-finished by vacuum evaporation plating means to form a first reflecting portion, and further, a skirt portion is provided on a peripheral edge of the rear surface of the optical body, and an appropriate portion of the first reflecting portion is provided. In addition to forming an indicator light condensing lens unit for transmitting the light flux of the operation indicator light to the front side of the optical body, the circuit block includes a photoelectric conversion element and an operation indicator light on the front surface, and has front and rear surfaces. A photoelectric sensor, comprising a circular circuit board on which an electronic component is mounted and whose peripheral edge abuts directly on the end face of the skirt portion or via a spacer. 6. The photoelectric sensor according to claim 5, wherein the casing is formed of a metal material, and the first and second recesses are provided with a first shielding body for shielding electromagnetic noise from outside. A photoelectric sensor, wherein a second shield is provided. 7. The first shield is formed of a circular metal plate fitted to the opening of the first recess, and the second shield is formed of a metal cylinder fitted to the second recess. The photoelectric sensor according to claim 6, wherein: 8. The photoelectric sensor according to claim 7, wherein said second shielding body includes a metal shielding plate having a through hole therein.