JP2512775B2 - Light sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical sensor for detecting that an object has entered a detection area.

BACKGROUND ART Generally, a reflection type optical sensor of this kind for detecting an object entering a detection area is, as shown in FIG. 4, a light projecting means 1 for projecting light to the detection area. And a light receiving means 2 for receiving the reflected light from the object X in the detection area,
It is composed of a signal processing means 3 for calculating and judging the presence or absence of the object X based on the output of the light receiving means 2 and outputting an object detection signal. Conventionally, this kind of optical sensor is as shown in FIG.
An optical block 5 in which the optical system of the light projecting and receiving means 1, 2 and the light projecting and light receiving elements are integrated, an electronic circuit block 6 in which an electronic circuit part of each means is mounted on a printed circuit board 20, and both blocks 5, 6 It is formed of an operation display unit 8 and a sensor function setting unit 9 provided in the die-cast case 7 for housing the. The optical block 5 includes a printed circuit board 12 on which a light emitting element 10 for projecting light and a light receiving element 11 for receiving reflected light are mounted, a light projecting lens 13 and a light receiving lens 14, and an O-ring.
It is composed of 15a, 15b, an optical tube 16, a lens retainer 17, and a rubber cover 18, and the optical block 5 can be obtained by adjusting and assembling these parts in advance.
During this adjustment and assembly, the optical axes of both lenses 13 and 14 and the distances between both lenses 13 and 14 and light emitting element 10 and light receiving element 11 are also adjusted and fixed.

On the other hand, the electronic parts (IC, transistor, resistor, capacitor, sensitivity adjustment VR, etc.) of the optical sensor body that consists of the drive circuit of the light emitting element 10, the conversion circuit of the light receiving element 11 output, the amplification circuit, the arithmetic circuit, the output circuit The electronic circuit block 6 is formed by being mounted on the printed circuit board 20. Further, the sensor function setting portion 9 is formed by the sensitivity setting knob 21 that is engaged with the groove of the rotation shaft of the sensitivity adjustment volume VR. Furthermore, a light emitting diode LD for operation display
Corresponding to the above, the operation display portion 8 is formed by the light diffusion block 22 attached to the display window provided in the die-cast case 7. In the figure, 23 is a lower cover that is attached to the lower surface opening of the case 7, and 24 is a lead wire such as a power supply line and a signal output line.

By the way, in such a conventional example, in the comprehensive assembly, the optical block 5 in which the light emitting and receiving means 1 and 2 are integrated, the electronic circuit block 6 in which the electronic circuit part of each means is mounted, and the light diffusion An operation display unit 8 such as block 22,
Although the sensor function setting section 9 such as the sensitivity setting knob 21 is incorporated in the case 7, the light emitting element 10 of the optical book 5 and the drive circuit of the electronic circuit block 6 are electrically connected by the shield wire 25. Wiring work for connection, alignment work between the sensitivity setting knob 21 of the sensor function setting unit 9 and the volume VR on the printed circuit board 20 of the electronic circuit block 6, and work for soldering the light receiving element 11 to the predetermined position 20a of the printed circuit board 20. Since it is necessary to assemble the operation display section 8 such as the light diffusion block 22 and the operation display light emitting diode LD on the printed circuit board 20 at the same time, the number of parts is increased and the assembly is performed. There is a problem that the work becomes troublesome, the cost becomes high, and the shape becomes large. That is, in the above conventional example, the work of connecting the optical block 5, the electronic circuit block 6, the operation display unit 8 and the sensor function setting unit 9 is
Since electrical, mechanical, and optical operations were performed separately, and the connection work was not standardized, the number of parts and the assembly man-hours increased, and the connection work became complicated, resulting in miniaturization and There was a problem that the price could not be easily reduced.

Then, as a solution to the above problems, there is an optical sensor using an optical wiring board 30 as shown in FIGS. 6 to 9. That is, the operation display unit 8, for example, a sensor function setting unit 9 such as a sensitivity setting unit for setting the detection sensitivity of an object, and the electronic circuit unit of each means are formed by using optical waveguides, mirrors, and the like. It is optically connected by a plate 30.

Here, the optical wiring board 30 for optically connecting the respective parts is provided with the optical waveguide 31.
₁ to 31 _6, 31 ₁ 'to 31 _4', 31 ₄ ', 31 _0, 31 _0, 31', 31 ₀ ", is formed by a mirror, a lens, a light output portion formed of a prism, light projection, receiving Lenses L ₁ and L ₂ for use with are integrally formed. The optical waveguide 31 _{1-31 6} ...... is molded of a synthetic resin (polymer material), is adapted to be formed by patterning using a photomask exposure using a photo-curable resin, Ya precision resin molding technology Since the optical wiring board 30 can be manufactured by applying the manufacturing technique of the integrated circuit based on the photomask operation, the cost can be easily reduced by mass production.

The optical wiring board 30 formed as described above is disposed via the spacer 32a on the mount board 32 made of ceramic or epoxy resin on which the chip parts of the electronic circuit part are mounted and printed wiring is provided, Light emitting element 10 for emitting light and light emitting element 33 for function setting mounted on the mount substrate 32.
a, operation display light emitting element 33b, margin display light emitting element 33c,
It is optically connected to the light receiving element 11 that receives the reflected light from the detection area and the function setting light receiving elements 34a to 34d. Also,
In the illustrated example, the light receiving element 11 for receiving the reflected light from the object X via the lens L ₂ and the optical waveguides 31 ₀ , 31 ₁ ′ to 31 ₃ ′, 31
_The light receiving elements 34a to 34d for receiving the light output from the ₄ ″ are 1
It is mounted on the mount substrate 32 as an integrated circuit 35 formed into a chip.

By the way, the sensor function setting unit 9 transmits the light from the light emitting element 33a for function setting, which is a light emitting source, to the optical waveguides 31 _{1 to} 31 ₄ , 31 ₁ ′.
To 31 ₄ ′, a slit 36a is provided which is multi-branched and spans a plurality of multi-branched branch optical paths, and a transmitted light amount varying means 37 for adjusting the amount of light of each branch optical path transmitted through the slits 36a. Is formed in the slit 36a, the light amount varying means 37 is an elliptical shape eccentrically attached to an operating portion 37a having a driver insertion groove and an axis protruding from the operating portion 37a. It is formed of light-shielding pieces 37b and 37c. Here, the light transmitted through the slit 36a by rotating the operation portion 37a (in the illustrated example, via the branched optical path consisting of the optical waveguides 31 ₂ and 31 ₂ ′ or the optical waveguides 31 ₃ and 31 ₃ ′) The amount of light (transmitted light) shielded by the light shield piece 37c or 37b (that is, the optical path cross-sectional area) can be adjusted. In the illustrated example, the slit 36
The collimating lenses L _{11 to} L ₁₄ for converting the light transmitted through a into substantially parallel rays are provided with the optical waveguides 31 _{1 to} 31 on one side of the slit 36 a.
₄ is provided on the output end surface of the slit 36a, and at the input end surface of the optical waveguides 31 ₁ ′ to 314 ₄ ′ on the other side of the slit 36 a, a condenser lens L ₁₁ ′ to
By providing L ₁₄ ′, the amount of transmitted light can be easily adjusted. Further, the one end portion that is bundled with the optical waveguide 31 _{1-31 4,} the light emitting element
Light input from 33a propagates is branched at a predetermined ratio to the optical waveguides 31 ₁ to 31 _4, is received sensor function set by the light receiving element 34a~34d adjusts the transmission amount by the transfer quantity changing means 36 It is supposed to be done. The optical waveguides 31 ₀ , 31 ₀ ′ and 31 ₀ ″ are for extracting a part of the light emitted from the light emitting element 10 for projecting as reference light and inputting it to the light receiving element 34a. The reference light transmitted through 31 ₀ ′, 31 ₀ ″ and the reference light transmitted through the optical waveguides 31 ₁ , 31 ₀ ′ are combined and incident on the light receiving element 34 a through the optical waveguide 31 _0. I am letting you. In this case, in the light receiving element 34a, the reference light transmitted via the optical waveguide 31 ₀ ′31 ₀ ″,
The reference light for setting the sensor function, which is transmitted through the optical waveguide 31 ₁ ′, is incident. However, by making the incident timing of both lights different, the light receiving element 34 for both reference lights
It eliminates the inconvenience caused by sharing a.

FIG. 9 shows an example of the structure of a reflecting portion for reflecting the reference light transmitted through the optical waveguide 31 ₀ ′ and inputting it to the optical waveguide 31 ₀ ″. FIG. 9A shows the mirror plate M _0. And the prism P ₀ is used in FIG.

Now, the light emitted from the light emitting element 10 of the light projecting means 1 is
A light beam is formed by the light projecting lens L _{1 and} projected onto the detection area, while the reflected light from the object X in the detection area is collected by the light receiving lens L ₂ of the light receiving means 2 and received. element
It is designed to be incident on 11, and in the signal processing means 3,
Based on the output of the light receiving element 11, it is determined whether or not the object X has entered the detection area, and the determination result is displayed on the operation display unit 8. Light emitted from the light emitting elements 33b and 33c for operation display and margin display is transmitted to the light diffusion block of the operation display unit 8 through the optical waveguides 31 ₅ and 31 ₆ and is then transmitted to the light diffusion block 22. By being scattered and radiated in the direction, it is displayed that the object has entered the detection area or has entered the vicinity (margin range) of the detection area. Further, the object detection processing in the signal processing means 3 is
This is performed by general signal processing, and in this object detection processing, in order to correct the variation in the light emission amount of the light emitting element 10 for projecting light, it is taken in through the optical waveguides 31 ₀ , 31 ₀ ′, 31 ₀ ″. The reference level is used to determine the output level of the light receiving element 11 based on the output of the light receiving element 34a.

By the way, the sensor function setting unit 9 uses the optical waveguides 31 _{1 to} 3 _1.
Slit 36a in the branch optical path split by 1 ₄ , 31 ₁ ′ 31 ₄ ′
By means of the transmitted light amount varying means 37 provided in the slit 36a, the amount of light transmitted through each of the branched optical paths formed by the optical waveguides 31 ₂ and 31 ₂ ′ and the optical waveguides 31 ₃ and 31 ₃ ′ is set appropriately. The light incident on the light-receiving elements 34b and 34c is adjusted by adjusting to (1), and the sensor function (for example, the detection sensitivity of the object X) is set. In this case, by rotating the operation portion 37a, it is possible to change the transmitted light amount of the two branched optical paths by the light shielding pieces 37b and 37c in an arbitrary relationship, and therefore, it is possible to use a plurality of (two in the illustrated example) sensor functions. Each parameter can be set at the same time, and the sensor function can be set easily. For example, when it is determined whether or not the object X has entered the detection area using the amount of received light and the distance measurement (a value obtained by optically measuring the distance to the object X), two parameters of the sensor function are set. Although it is necessary to set each of them, in the illustrated example, the parameters of the two types of sensor functions can be set at the same time by simply turning the operation portion 37a appropriately, and the setting of the sensor functions can be easily performed. Here, the light transmitted through the optical waveguides 31 ₁ and 31 ₁ ′ is the reference light at the time of function setting, and the level of the light receiving elements 34b and 34c output is based on the output of the light receiving element 34a that received this reference light. By determining the above, it is possible to correct the variation in the light emission amount of the function setting light emitting element 33a.

FIGS. 10 to 12 show a branched optical path formed by using a prism P ₁ , and a plurality of first optical waveguides 31 ₁ in which light from a light emission source is incident from one end face and the other end face is arranged on the same face 31 ₁ ~ 31
₄ and a plurality of second optical waveguides 31 ₁ ′ to 314 ₄ ′, one end surface of which is disposed on the same surface and which allows the light output from the other end surface to enter the light receiving elements 34 a to 34 d, 1. Second optical waveguides 31 _{1 to} 31 ₄ and 31 ₁ ′ to 314 ₄ ′ are arranged facing each other with an appropriate distance, and the light output from the first optical waveguides 31 _{1 to} 31 ₄ is refracted or reflected to respond. Second optical waveguide 31 ₁ ′
To 31 ₄ ′ to form a plurality of branched optical paths with the reflection means 40, and the first and second optical waveguides 31 _{1 to} 3 1 arranged on the same plane.
1 _4, 31 ₁ 'to 31 _4' is obtained by forming a slit 36a between the end face and the light output surface of the reflection means 40. Here, in the illustrated example, the prism P ₁ is used as the reflecting means 40, and the light output from each of the optical waveguides 31 _{1 to} 31 ₃ is reflected twice (90 ° reflection) and the corresponding optical waveguide 31 is reflected. _The light is made incident on 1'-31 ₃ '. Further, the transmitted light amount varying means 37 includes a diaphragm plate 41 having a diaphragm hole 41a of an appropriate shape, and a rotating disk 42 around which a large number of pores 43 are formed by gradually changing the density.
And the knob 42 formed on the rotary disc 42.
By rotating a, the number of pores 43 exposed to the aperture 41a can be changed, and the amount of transmitted light can be changed.

However, in the conventional example as described above, the electronic circuit section, the operation display section 8, and the sensor function setting section 9 are
By making optical connection with the optical wiring board 30 formed by using an optical waveguide, a mirror, etc., it is possible to reduce the number of parts and simplify the assembly work, and it is possible to easily reduce the size and cost. Although it is possible to easily set a plurality of sensor functions with a simple configuration, there is a problem that malfunction may occur due to mutual interference of lights propagating in the branch optical paths. For example, thirteenth
As shown in FIG. (A), the lens L ₁₁ 'when there is aberration in the lens L _11' not coupled to the optical waveguide 31 ₁ 'is collected light corresponding with, neighboring optical waveguide In some cases, the light may directly enter the 31 ₂ ′, or as shown in FIG. 13B, the light propagating in the clad may enter the adjacent optical waveguide 31 ₂ ′.
Further, as shown in FIG. 14, the fluctuation of the refractive index of the core or cladding to form an optical waveguide 31 ₁ 'to 31 _4', interface failure, leakage light propagating through such bending of the waveguide,
In some cases, the adjacent optical waveguides 31 ₁ ′ to 314 ₄ ′ are coupled. In such a case, there is a problem in that the sensor function adjustment by the transmitted light amount varying means 37 cannot be performed in a predetermined curve, and a malfunction occurs. That is, in the case where the transmitted light amount varying means 37 is formed so that the light transmitted through the slit 36a is linearly shielded, the light receiving element 34a for receiving the reference light output from the optical waveguide 31 ₁ ′.
The ratio Ib / Ia of the light-receiving element 34b outputs Ib for receiving an output Ia, the function setting light output from the optical waveguide 31 _2, the optical waveguide 3
If there is no mutual interference due to light leakage between adjacent branch optical paths including 1 ₁ ′ and 31 ₄ ′, it changes linearly. However,
If there is mutual interference due to light leakage between adjacent branch optical paths,
Ib / Ia does not change linearly, function setting is not performed correctly, and malfunction occurs.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to reduce the number of parts to simplify the assembling work, and to reduce the size and cost. It is an object of the present invention to provide an optical sensor that can be easily realized and that can prevent malfunction due to mutual interference of lights propagating in juxtaposed optical waveguides.

DISCLOSURE OF THE INVENTION (Structure) The present invention includes a light projecting unit that projects light onto a detection area, a light receiving unit that receives direct light from the light projecting unit or reflected light from an object in the detection area, and light receiving unit. Signal processing means for calculating and determining the presence or absence of an object based on the output of the means and outputting an object detection signal, display light emitting means for displaying the determination result based on at least the object detection signal, and setting for sensor function setting Light emitting means for setting and light receiving means for setting for receiving light from the setting light emitting means, an operation display section for displaying a determination result by the light emitted by the display light emitting means, and light from the setting light emitting means. And a sensor function setting section for setting a sensor function such as detection sensitivity by causing the setting light receiving means to receive light, and an optical wiring board formed by using an optical waveguide, a mirror, etc. Configure The optical sensor constituted by the light connected to the sub-circuit portion having thereon a dummy optical waveguide for optical path separating it has almost the same depth as the optical waveguide between the optical waveguides which are juxtaposed in the optical wiring board,
Assembling work can be simplified by reducing the number of parts, and size and cost can be easily reduced.
Moreover, it is intended to provide an optical sensor capable of preventing malfunction due to mutual interference of lights propagating in juxtaposed optical waveguides.

(Embodiment) FIG. 1 and FIG. 2 show an embodiment of the present invention, but since the basic structure of this embodiment is common to the structure of the conventional example shown in FIG. 7, it is common. The same reference numerals are given to the parts, and some of them are omitted in the drawing. In the present embodiment, the light projecting means 1 for projecting light to the detection area, the light receiving means 2 for receiving the direct light from the light projecting means 1 or the reflected light from an object in the detection area, and the light receiving means 2 output. A signal processing unit 3 for calculating and determining the presence or absence of an object based on the output based on the object detection signal, an operation display light emitting element 33b for displaying a determination result based on at least the object detection signal, and a function for setting a sensor function. The setting light emitting element 33a and the function setting light receiving elements 34a to 34d that receive light from the function setting light emitting element 33a.
And a function display light receiving element 34a to modulate the light from the function setting light emitting element 33a by displaying the operation display portion 8 in which the determination result is displayed by the light emitted from the operation display light emitting element 33b.
The sensor function setting section 9 for setting the sensor function such as the detection sensitivity of the object by receiving light from the 34d and the optical wiring board 30 formed by using an optical waveguide, a mirror, etc. Optically connected to the circuit section, the light from the light source is multi-branched by the optical waveguides 31 _{1 to} 31 ₄ , 31 ₁ ′ to 31 ₄ ′, and the slit spans a plurality of multi-branched optical paths.
In the optical sensor in which the sensor function setting section 9 is formed by providing the transmission light amount varying means 37 for adjusting the light amount of each branched optical path transmitted through the slit 36a in the optical sensor, it is provided with a dummy optical waveguide 45 of the optical path separating it has almost the same depth as the optical waveguide 31 ₁ 'to 31 _4' 30 of juxtaposed optical waveguides 31 ₁ 'to 31 _4' between.

In the embodiment, it is provided with the dummy optical waveguide 45 only between the optical waveguide 31 ₁ 'to 31 _4', the other optical waveguide 31 ₁ to 31 ₄
A similar dummy optical waveguide may be provided between the two if necessary. Also, prevent mutual interference due to light leakage reliably is a dummy optical waveguide 45 it is necessary to provide the entire length or more optical waveguides 31 ₁ 'to 31 _4', in the case of reducing the light leakage The dummy optical waveguide 45 may be provided only in a place where light leakage easily occurs.

FIG. 3 shows a state in which the mutual interference of the light propagating in the branched optical path can be prevented by providing the dummy optical waveguide 45. The optical OP coupled to the adjacent optical waveguide 31 ₂ ′ by the aberration of the lens L ₁₁ ′ is shown. consider _1, and a light OP ₂ binding 'leaks from the optical waveguide 31 ₂ next' optical waveguides 31 ₁ to. Lens now
The light OP ₁ due to the aberration of L ₁₁ ′ propagates through the dummy optical waveguide 45, and then a small amount of light leaking from the dummy optical waveguide 45 is coupled to the adjacent optical waveguide 31 ₂ ′. Will act as a buffer mechanism, and the mutual interference of light will be greatly improved. According to experiments, dummy optical waveguide
The effect of improving mutual interference by providing 45 was about 10 dB. However, the optical waveguides 31 ₁ used in the experiment ', 31 _2' and the refractive index n ₂ of the refractive index n ₁ and a cladding of the core of the dummy optical waveguide 45 (the base material of the optical wiring board 30) is located at 1.56,1.49 The optical waveguides 31 ₁ ′ and 31 ₂ ′ have a cross section of 0.4 × 1.0 mm and a length of about 20 mm. Next, with respect to the light OP ₂ leaked from the optical waveguide 31 ₁ ′, the improvement of the mutual interference by the dummy optical waveguide 45 was confirmed by the same principle as the case of the above optical OP ₁ , and the improvement effect was about 15 dB. It was

Although the dummy optical waveguide 45 is formed in a rectangular cross section in the embodiment, it may be V-shaped or U-shaped. Further, the refractive index of the core of the dummy optical waveguide 45 may be higher than that of the clad (base material of the optical wiring board 30), and the other optical waveguides 31 _{1 to} 31 ₆₄ , 31 ₁ ′ to 31 ₄ ′ ... Since it can be formed in the same process as that of the core, the manufacturing process of the optical wiring board 30 can be simplified, and the mutual interference preventing mechanism can be added without increasing the cost.

[Advantages of the Invention] As described above, the present invention includes a light projecting unit that projects light to a detection area, and a light receiving unit that receives direct light from the light projecting unit or reflected light from an object in the detection area. Signal processing means for calculating and determining the presence or absence of an object based on the output of the light receiving means and outputting an object detection signal, display light emitting means for displaying the determination result based on at least the object detection signal, and sensor function setting The setting display light emitting means and the setting light receiving means for receiving the light from the setting light emitting means, the operation display section for displaying the determination result by the light emitted from the display light emitting means, and the setting light emitting means. A sensor function setting section for setting a sensor function such as detection sensitivity by modulating light and receiving it by the setting light receiving means is an optical wiring board formed by using an optical waveguide, a mirror, etc. Make up In the optical sensor that is optically connected to the electronic circuit part,
A dummy optical waveguide for optical path separation having a depth substantially equal to that of the optical waveguides is provided between the optical waveguides arranged side by side in the optical wiring board. Since the optical wiring board is used, the number of parts is reduced. As a result, the assembling work can be simplified, the miniaturization and the cost reduction can be easily performed, and since the dummy optical waveguide is provided between the optical waveguides arranged in parallel,
There is an effect that it is possible to prevent malfunction due to mutual interference of lights propagating in the optical waveguides arranged in parallel.

[Brief description of drawings]

FIG. 1 is a top view of an essential part of an embodiment of the present invention, FIG. 2 is a sectional view of the essential part of the same, FIG. 3 is an operation explanatory view of the same, FIG. 4 is a schematic configuration diagram of a conventional example, and FIG. Is an exploded perspective view of the same as above, FIG. 6 is an exploded perspective view showing a schematic configuration of another conventional example, FIG. 7 is a top view of relevant parts of the same, FIG. 8 is a sectional view of relevant parts of the same, and FIG. FIG. 10 is a top view of a main part of another conventional example, FIG. 11 is a top view of a main part of the same as above, FIG. 12 is a front view of the main part of the same, FIG. 13 and FIG. The figure is a diagram for explaining the operation of the above. Reference numeral 8 is an operation display unit, 9 is a sensor function setting unit, 30 is an optical wiring board, 31 _{1 to} 31 ₄ , 31 _{1 to} 31 ₄ ... Are optical waveguides, and 45 is a dummy optical waveguide.

Claims (1)

(57) [Claims] 1. A light projecting means for projecting light to a detection area, a light receiving means for receiving direct light from the light projecting means or reflected light from an object in the detection area, and an object of the object based on an output of the light receiving means. Signal processing means for calculating and determining presence / absence and outputting an object detection signal, display light emitting means for displaying a determination result based on at least the object detection signal, setting light emitting means for sensor function setting, and setting light A setting light receiving unit for receiving light from the light emitting unit, an operation display unit for displaying a determination result by the light emitted from the display light emitting unit, and a setting light receiving unit for modulating the light from the setting light emitting unit. A sensor function setting section for setting sensor function such as detection sensitivity by receiving light from the means and an optical wiring board formed by using an optical waveguide, a mirror, etc. Connect Light sensor in the optical sensor, characterized in that a dummy optical waveguide for an optical path separating it has almost the same depth as the optical waveguide between the optical waveguides which are juxtaposed in the optical wiring board that.