JPH09265880A - Area sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve reduction of wiring and miniaturization and cost reduction of the sensor head of a two-dimensional area sensor by decreasing the number of photoelectric sensors, etc., that are in use. SOLUTION: This area sensor is designed so that light projected from a projecting part 2 is transmitted to a receiving part 3 as it undergoes multiple reflections between two opposite reflectors 4, 6 that use one-dimensional prisms. If an object advances into the optical path leading from the projecting part 2 to the receiving part 3 and blocks the light, the advance of the object is detected on the basis of fluctuation of the signal input to the receiving part 3. Only one unit having photoelectric sensor functions is enough, and miniaturization of the sensor, etc., can be achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is based on a fluctuation of a light receiving signal in a light receiving section when an object enters a light propagation path of a light emitted from a light projecting section and reaching a light receiving section to block the light. , A two-dimensional area sensor for detecting the presence or absence of an object.

[0002]

2. Description of the Related Art Conventionally, a sensor called an area sensor has been used for prevention of danger in a manufacturing line of a factory and detection of intrusion of a suspicious person in a house or the like. FIG. 15 is a diagram schematically illustrating the appearance and operation of a conventional area sensor. As shown in the figure, this conventional area sensor 100
Is a light emitting system head 102 having a plurality of light emitting elements 101 arranged on a straight line, and a light receiving system head 104 having a plurality of light receiving elements 103 arranged on a straight line, facing each other with a detection distance D therebetween. It monitors two-dimensional areas.

When the opaque object 105 enters so as to block the detection area A of the area sensor 100 having such a structure, a part of the light L projected from the projection system head 102 is blocked by the opaque object 105. Therefore, the opaque object 105
Can be detected.

[0004]

However, the conventional area sensor as described above has a plurality of light emitting elements 101.
Also, since the light receiving element 103 is used, not only the cost becomes high, but also there are problems such as a limit in downsizing the sensor heads 102 and 104 and complication of wiring. Especially when the detection area A is large or the detection resolution S is high,
These problems are more serious because a larger number of light emitting elements 101 and light receiving elements 103 are required.

The present invention has been made to solve the above-mentioned problems, and is based on the multiple reflection principle of a one-dimensional prism.
The light emitted from the light projecting section is propagated in the direction of the light receiving section between two opposing reflecting plates and is incident on the light receiving section, so that the number of light projecting elements and photoelectric sensors used is greatly reduced. It is an object of the present invention to provide an area sensor capable of saving wiring, downsizing a sensor head, and reducing costs.

[0006]

In order to achieve the above object, the present invention provides a light projecting section for emitting light, and a light receiving section for receiving the light emitted from the light projecting section and converting it into an electric signal. In an area sensor that detects the presence or absence of an object based on a change in a light reception signal at the light receiving unit due to an object entering the light path from the light emitting unit to the light receiving unit and blocking light, A first reflecting plate arranged between the light receiving units and a second reflecting plate arranged so as to face the reflecting plate are provided, and light is emitted from the light projecting unit toward the second reflecting plate. The second reflecting plate reflects the light toward the first reflecting plate, so that the light is propagated while being multiply reflected between the two reflecting plates and is incident on the light receiving portion.

In the above structure, the light emitted from the light projecting portion toward the second reflection plate is further reflected by the second reflection plate toward the first reflection plate, and is continuously reflected by both. It propagates while being multiple-reflected between the plates and enters the light receiving portion. For this reason, when some light opaque object enters the light propagation path, the light does not reach the light receiving unit, and the entry of the object is detected. Moreover, in this configuration, since the light projecting section and the light receiving section are only one set, it is possible to greatly reduce the number of light projecting elements and photoelectric sensors used and to reduce wiring.

Further, in the present invention, at least one of the reflectors may have a regressive reflection characteristic in at least one axial direction. In this configuration, the light emitted from the light projecting unit is propagated while being accurately reflected multiple times due to the recursive reflection characteristic in the uniaxial direction, and is incident on the light receiving unit, so that the same operation as described above can be obtained.

Further, according to the present invention, the light projecting section has an element that emits visible light and an element that emits infrared light, and these lights are combined and projected by a half mirror. Good. With this configuration, the attachment adjustment becomes easy.
In addition, since an element that emits infrared light generally has higher emission power, the detection distance of the sensor can be extended. In addition, the glare of light rays during sensor operation is reduced,
Moreover, the operation sensitivity does not decrease.

Further, the present invention may be such that an element that emits visible light is caused to emit light only when the area sensor is attached and adjusted. In this configuration, adjustment at the time of mounting adjustment is easy, and since visible light is not normally emitted, a passerby or a user may feel uncomfortable or suspicious due to glare of light rays during sensor operation. Absent.

Further, the present invention can be an intruder detection system for detecting an intruder using the area sensor.

The present invention also provides a danger prevention system which detects an object or the like using the area sensor and stops the operation of the apparatus when the detection is performed.

Further, the present invention can be a part removal forgetting monitoring system for detecting whether or not a part is taken out by using the area sensor.

The present invention can also be applied to a fallen object detection system for detecting a falling object using the area sensor.

Further, according to the present invention, when a plurality of sets of the above area sensors are used side by side, a reflecting plate is provided on the back side of the sensor head provided with the light projecting portion, the light receiving portion and the reflecting plate. Good. In this configuration, the reflector on the back surface side of one of the sensor heads of the two adjacent area sensors can be used for the other sensor head, and the efficiency of attaching the reflector can be improved.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining the appearance and operation of the area sensor of the present invention. As shown in the figure, the area sensor 1 includes a light projecting unit 2 that emits light L.
And a light receiving section 3 for receiving the light L emitted from the light projecting section 2 and converting it into an electric signal, and the light projecting section 2, the light receiving section 3,
And a sensor head 5 composed of the first reflecting plate 4 provided between them, and further, a second reflecting plate 6 provided so as to face the first reflecting plate 4. Then, the light L emitted from the light projecting unit 2 toward the second reflection plate 6 is reflected by the second reflection plate 6, and this reflected light L is incident toward the first reflection plate 4, and further, , So that the light L is reflected by the first reflection plate 4 and is incident on the second reflection plate 6, that is, the light L is multiply reflected between the first and second reflection plates 4 and 6, and this multiple reflection is The light L is propagated while repeating, and is incident on the light receiving unit 3. In the area sensor 1 having such a configuration, an optical path from the light projecting section 2 to the light receiving section 3 serves as a detection area for an object or the like. The amount of received light varies, and based on this, the entry of an object or the like can be detected.

FIG. 2 is a diagram showing the structure of the reflectors 4 and 6 used in the embodiment of the present invention. FIG. 2A shows the relationship between the incident angle and the output angle and the xz plane, and FIG. Indicates the mode of incidence and emission on the plane (A plane) that cuts the y-axis. As shown in the figure, the reflectors 4 and 6 have a one-dimensional prism 10 whose cross-sectional shape is an isosceles right triangle, and the light L
Are emitted at an emission angle θ ′ (−θ with respect to the z axis) that is the same as the incident angle θ, and sequentially propagate along the y axis. Further, when the spread light L is incident, it is reflected and then condensed, so that the light intensity of the light projecting portion can be effectively used,
The light L is efficiently multiple-reflected and reaches the light receiving portion.

FIG. 3 is a circuit block diagram of an embodiment of the area sensor of the present invention. As shown in the figure, the circuit in this embodiment includes a light projecting unit 2, a light receiving unit 3, and a signal processing circuit 11. Light L emitted from the light projecting unit 2
Is propagated after being multiple-reflected between the two reflection plates, is incident on the light receiving section 3, and is processed by the signal processing circuit 11. For example, the output becomes Hi or Lo with and without light input.

4 (a) and 4 (b) are a sectional view of the sensor head 5 and a plan view of the light projecting section 2 in an embodiment of the area sensor of the present invention. As shown in the figure, the sensor head 5 includes a light emitting diode 2a, a collimator lens 2b, and an emission angle (tilt) adjusting mechanism 2c built in a housing 5a.
A light projecting section 2 including a light receiving section 3 including a photodiode 3a and an imaging lens 3b, a signal processing circuit 11, and a first reflecting plate 4 provided between the light projecting section 2 and the light receiving section 3.
And a protective cover 5b for protecting them. In the emission angle adjusting mechanism 2c, the substrate 2d to which the light emitting diode 2a and the collimating lens 2b are attached is attached to the housing 5a.
It is configured to be attached to the back plate by using screws or the like at at least two points in the emission angle adjusting direction.

According to this structure, only one set of the light projecting section 2 and the light receiving section 3 is built in the housing 5a of the sensor head 5. Therefore, as compared with the conventional area sensor 100 that uses a plurality of light projecting elements 101 and light receiving elements 103, the inside of the housing 5a is not occupied by the plurality of light projecting elements 101 and light receiving elements 103. . Therefore, the sensor head 5 can be downsized.

Light emitting diode 2 as a light source of the light projecting section 2.
As for a, a small light emitting portion is preferable from the viewpoint of effectively utilizing the light intensity. For example, the emission spot diameter is 3
0 micron surface emitting diode 2a, diameter 3.8m
When combined with the lens 2b having an m and a focal length of 3.65 mm, a full divergence angle of 0.47 degrees (a spot diameter of 1 mm ahead of 8.22 mm) can be obtained. Incidentally, spread angle = ta
n ⁻¹ (emission spot diameter / lens focal length), spot diameter = ((observation distance cf. 1000 mm) × emission spot diameter) / lens focal length. Further, the imaging lens 3b of the light receiving unit 3 has a larger numerical aperture (NA) and a larger lens diameter, and is preferable, but from the viewpoint of downsizing, a diameter of 10 mm to 20 mm is preferable.

Further, since one-dimensional prisms are used for the reflecting plates 6 and 4, in this case, since the spread of the beam after reflection is particularly small, the light utilization efficiency is improved. Further, it is preferable that the period (pitch) of the prism is small, for example, about several hundreds of microns. However, when the period is less than several tens of microns, interference also occurs in the light emitting diode, so that the spread occurs. Incidentally, the period of the prism ≧ coherence length, coherence length = (wavelength of light source) ² / (2π × refractive index × emission spectrum width).

The resolution can be improved by reducing the diameter of the lens 3b and the divergence angle of the light from the light source, particularly when the diameter of the lens 3b of the light receiving section 3 is used. Further, the detection distance can be lengthened by reducing the beam optical axis angle of the light projecting unit 2, improving the light emission intensity of the light source, and reducing the reflection loss of the reflection plates 4 and 6.

FIGS. 5A and 5B are views for explaining an example of forming a reflection plate in one embodiment of the area sensor of the present invention. FIG. 5A shows a triangular prism and a substrate, and FIG. Each prism shape has a pentagonal structure in cross section, the apex angle portion is a right angle, and the adjoining sides have the same length. As a method for manufacturing the reflection plates 4 and 6, a 2P (photopolymerization) method using an ultraviolet curable resin or the like can be used. Incidentally, in the case shown in (a), the substrates 4b, 6
If glass is used for b and is integrated with the prism parts 4a and 6a made of resin, it is possible to prevent the reflection plates 4 and 6 from being warped by an external force. Further, in the structure shown in (b), the reflectors 4 and 6 are strong against external stress due to their integrated thickness. Furthermore, if the entire reflectors 4 and 6 are formed into a film and the back side is an adhesive sheet, the work of assembling as a sensor becomes easy.

FIG. 6 is a view for explaining an example of forming the reflection plates 4 and 6 in the embodiment of the area sensor of the present invention.
(A) is a combination of the biconvex cylindrical lens arrays 4c, 6c and the mirrors 4d, 6d, (b) is a single convex cylindrical lens array 4e, 6e and the mirror 4
It is a combination of d and 6d. In any case, since both are molded and adhered with a material having a refractive index smaller than that of the lens material, miniaturization can be achieved.
The mirror is installed at the focal position of the lens.

7A and 7B are views for explaining the structure of the light projecting portion 2 in the embodiment of the area sensor according to the present invention. FIG. 7A is a plan view and FIG. 7B is a longitudinal sectional view. As shown in the figure, the light projecting section 2 has two elements, a semiconductor laser (which may be a visible light emitting diode) 21 which emits visible light and an infrared light emitting diode 22 which emits infrared light, in a housing 20. The light is projected through the half mirror 23 and the light projecting lens 24. According to this configuration, when the sensor is normally used, it is possible to prevent discomfort or suspiciousness due to glare during sensor operation by using infrared light. By using it, the optical axis can be easily adjusted. Further, when laser light is used as the light projecting light source, the spread of the beam is smaller than that of the light emitting diode and the light emitting power is large, so that it is possible to easily increase the detection distance and increase the resolution.

FIG. 8 shows a modification of the area sensor 1 of the present invention. In this example, the sensor heads 5 arranged to face each other
The second reflection plate 6 and the second reflection plate 6 are provided in an integrated housing 25. With this configuration, when the sensor itself is small, the housing 2
By setting 5 appropriately, the optical axis adjusting mechanism of the reflectors 4 and 6 and the light emitting and receiving parts 2 and 3 becomes unnecessary.

FIG. 9 shows still another modified example of the area sensor 1, in which each of the separate sensor heads 27 and 28 is provided with a light projecting section 2 and a light receiving section 3, respectively. In this configuration, the reflection plate 4 is provided between the light projecting unit 2 and the light receiving unit 3.
6 is provided, which is the same as in the above-described embodiment, but since the light projecting unit 2 and the light receiving unit 3 are provided in separate sensor heads 27 and 28, parts are provided in each sensor head 27, 28. Can be distributed over the housing.

FIG. 10 is a diagram showing an embodiment of an intruder detection system using the area sensor of the present invention. This intruder detection system 31 is one in which the area sensor 1 is installed at a doorway 32 of a precious metal store or the like, and the light L is blocked by an intrusion of a suspicious person 33 or the like, and the intrusion can be detected. Then you can ring an alarm bell.

FIG. 11 shows an area sensor of the present invention,
It is a figure which shows the danger prevention system of a sputtering device. This danger prevention system 41 has an area sensor 1 installed in the opening on the operator side of the sputtering device 42, and when the hand or the like enters, the light L is blocked and the operation of the device is stopped.

FIG. 12 is a view showing a part removal forgetting monitoring system using the area sensor of the present invention. The part-forgetting monitoring system 51 monitors an area sensor corresponding to an opening of each parts shelf 52 in order to monitor whether all kinds of parts 53 are taken out from the parts shelf 52 divided into a plurality in a manufacturing factory or the like. 1 is arranged. Each time a component is taken out (picked) by using this sensor, it is detected, and the detection signal is used to manage the number of components by the counter 54 to issue a predetermined warning.
By adopting this system 51, in assembling a product composed of a large number of parts, it is effective in forgetting to take out the parts and eventually preventing defective products. Furthermore, since the area sensor 1 is designed to be compact and have reduced wiring, it can be compactly installed on each component shelf 52.

FIG. 13 shows an example of a structure suitable when a plurality of area sensors of the present invention are arranged and used. This sensor head 65 has the same structure as that of FIG.
A reflector 6 ′ is integrally provided on the plate 6. By using a plurality of sets of sensor heads 65 having such a configuration as a set, it is not necessary to separately install a member corresponding to the second reflection plate, and the mounting efficiency can be improved. In particular, like the component shelf 52 described above, the area sensor 1
It is possible to significantly reduce the cost when using a plurality of lining up.

FIG. 14 is a diagram showing a falling object detection system using the area sensor of the present invention. The falling object detection system 71 has the area sensor 1 arranged so that the number of objects 73 conveyed on the belt conveyor 72 can be counted. Accurate counting is possible even if the position is indefinite. Further, since the area sensor 1 is suitable for downsizing and wiring saving, the area sensor 1 can be easily configured even when the belt conveyor 72 is located near a wall or when it is difficult to obtain power.

The area sensor of the present invention is arranged between the light projecting section for emitting light, the light receiving section for receiving the light emitted from the light projecting section and converting it into an electric signal, and between the light projecting section and the light receiving section. However, the present invention is not limited to the above-mentioned embodiment, as long as it includes two reflecting plates for propagating the light emitted from the light projecting section to the light receiving section by multiple reflection. For example, a Fresnel lens may be used as the imaging lens for further size reduction. Further, as a system using the area sensor of the present invention, for example, a system that accurately stops the manufacturing line when a hand or the like enters a wafer transfer process in a semiconductor manufacturing line that requires a strict clean state is possible. .

[0035]

As described above, according to the area sensor of the present invention, the light emitted from the light projecting portion is propagated to the light receiving portion while being multiply reflected between the two reflecting plates.
When an object enters the optical path, the object can be detected based on the fluctuation of the light receiving signal of the light receiving unit. For this reason,
Compared with a conventional area sensor that uses a plurality of units having a photoelectric sensor function, the number of photoelectric sensors can be reduced and the wiring can be saved accordingly, and the size of the device can be reduced.

Further, according to the present invention, when the area sensor is incorporated in various devices and systems, the installation space can be made smaller and the wiring process can be made simpler. The system can be easily configured as a system for risk prevention in the process, management for taking out parts, intrusion monitoring of a suspicious person, and the like.

[Brief description of drawings]

FIG. 1 is an external view of an area sensor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a reflector used in an embodiment of the present invention, in which (a) is an incident angle and an outgoing angle and x−.
FIG. 3B is a perspective view showing the relationship with the z-plane, and FIG. 3B is a side view showing the mode of incidence and emission on the plane cutting the y-axis.

FIG. 3 is a circuit block diagram according to an embodiment of an area sensor of the present invention.

4A and 4B are respectively a cross-sectional view of a sensor head and a plan view of a light projecting unit according to an embodiment of an area sensor of the present invention.

5 (a) and 5 (b) are perspective views each showing an example of forming a reflection plate according to an embodiment of the area sensor of the present invention.

6 (a) and 6 (b) are perspective views showing an example of forming a reflection plate according to the embodiment of the area sensor of the present invention.

7 (a) and 7 (b) are respectively a plan view and a vertical cross-sectional view of a light projecting section in an embodiment of the area sensor of the present invention.

FIG. 8 is a perspective view showing a modified example of the area sensor of the present invention.

FIG. 9 is a perspective view showing another modification of the area sensor of the present invention.

FIG. 10 is a diagram showing an embodiment of an intruder detection system using the area sensor of the present invention.

FIG. 11 is a diagram showing an embodiment of a danger prevention system using the area sensor of the present invention.

FIG. 12 is a diagram showing an embodiment of a part removal forgetting monitoring system using the area sensor of the present invention.

FIG. 13 is a perspective view showing an embodiment of a sensor head suitable when a plurality of area sensors of the present invention are arranged and used.

FIG. 14 is a diagram showing an example of a falling object detection system using the area sensor of the present invention.

FIG. 15 is an external view of a conventional area sensor.

[Explanation of symbols]

 1 Area Sensor 2 Light Emitting Section 3 Light Receiving Section 4 First Reflector 5 Sensor Head 6 Second Reflector L Light

Claims (9)

[Claims] 1. A light projecting unit that emits light and a light receiving unit that receives the light emitted from the light projecting unit and converts the light into an electric signal, and is provided in an optical path from the light projecting unit to the light receiving unit. In an area sensor for detecting the presence or absence of the object based on a change in a light reception signal in the light receiving section due to an object entering and blocking light, a first reflection arranged between the light projecting section and the light receiving section. A board,
A second reflecting plate arranged so as to face the reflecting plate, and emits light from the light projecting section toward the second reflecting plate,
By reflecting light toward the first reflector by the second reflector, the light is propagated while being multiple-reflected between the two reflectors and is incident on the light receiving portion. Area sensor to do. 2. The area sensor according to claim 1, wherein at least one of the reflectors has a recursive reflection characteristic in at least one axis direction. 3. The light projecting unit has an element that emits visible light and an element that emits infrared light, and these lights are combined and projected by a half mirror. 1
Area sensor described in. 4. The area sensor according to claim 3, wherein the element that emits the visible light is caused to emit light only when the area sensor is attached and adjusted. 5. An intruder detection system, which uses the area sensor according to claim 1 to detect an intruder. 6. A danger prevention system characterized by detecting an object or the like by using the area sensor according to claim 1, and stopping the operation of the apparatus when the detection is performed. 7. A part removal forgetting monitoring system, which detects whether or not a part is taken out by using the area sensor according to claim 1. 8. A fallen object detection system, which detects a fallen object using the area sensor according to claim 1. 9. When a plurality of area sensors according to claim 1 are used side by side, a reflecting plate is provided on the back side of the sensor head provided with the light projecting portion, the light receiving portion and the reflecting plate. Characteristic area sensor.