JPH07280951A - Reflection type optical sensor - Google Patents

Abstract

PURPOSE:To provide a reflection type optical sensor which can accurately detect even an object having a mirror characteristic as metal has and an object with a high reflection factor, for example, white paper by lights different in wavelength projecting onto a reflector, reflector having a characteristic of reflecting light with some wavelength intensely, and detecting changes in the quantity of the light received as caused when the object intercepts the reflected light to judge the object. CONSTITUTION:Lights different in wavelength from each other are emitted separately from light emitting elements 1a and 1b and the outgoing lights are combined to be projected to a reflector 3 or an object 8. The reflector 8 has a characteristic with the reflection factor thereof different for each of the outgoing lights with the different wavelengths from the light emitting elements and thus, when the object 8 intercepts the reflected light in the optical path of the light projected and reflected, the quantity of reflected light with the respective wavelengths changes as received with a photodetecting part 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type optical sensor for determining the type or presence of a target object by projecting light on the target object and receiving the reflected light.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 27, as a reflection type optical sensor, a light projecting portion a and a light receiving portion b are provided, and light is projected from a light projecting portion a to a reflector c and the reflected light is reflected. There is a structure in which the light receiving unit b receives light, and it detects that the amount of light received by the light receiving unit b changes due to light being blocked when the detection object d enters the optical path, and thus detects the detection object d. .

[0003]

However, in the optical sensor as described above, when the detection object d has a mirror surface characteristic like metal, the light from the light projecting portion a is reflected by the detection object d, Since the light is received by the light receiving section b, the detected object d
There was a problem that it could not be detected even though it passed. In order to solve this, the light projecting unit uses a polarizing filter to project light having only a certain polarization component to the reflection plate, and the reflection plate has the polarization component of the reflected light perpendicular to the polarization component of the incident light. A corner cube or an assembly of corner cubes is used, and the light receiving unit is configured to receive only the polarization component perpendicular to the polarization component projected by the polarization filter, and the reflected light from the reflector is received by the light receiving unit. However, there is an apparatus that does not receive the reflected light from the detection object having the mirror surface characteristic in which the polarization component of the reflected light is the same as that of the incident light.
However, even in such a device, there is a problem that the reflected light of the detection object, which has a high reflectance like white paper and the polarization component of the reflected light is random, is received by the light receiving unit, and malfunctions. . Further, in recent years, it has been desired to increase the distance of the reflective photoelectric sensor. However, when the distance between the light emitting unit or the light receiving unit and the reflector is increased, when the distance reaches a certain limit, it becomes smaller than the reflected light amount of a highly reflective detection object such as white paper at a short distance. Therefore, there is a problem that the detection object and the reflection plate cannot be distinguished.

The present invention solves the above-mentioned problems by projecting light onto a reflector using an element that emits light of different wavelengths and an optical filter that synthesizes the light, and the reflector can emit light of any wavelength. , Which has the property of strongly reflecting the light of
By detecting changes in the reflected light of multiple wavelengths at the light receiving part when the detected object blocks the reflected light, the detected object can be distinguished, so that it is a detected object having mirror-like characteristics such as metal. In addition, it is an object of the present invention to provide a reflective optical sensor that can reliably detect an object such as a white paper that has a high reflectance and that can reliably detect the object even if the distance to the reflector is long.

[0005]

In order to achieve the above object, the invention of claim 1 is such that a light projecting portion, a reflecting plate for reflecting the light projected from the light projecting portion, and the reflecting plate or the object. A light receiving unit for receiving the reflected light, and by detecting that the reflected light amount received by the light receiving unit changes when the object shields the reflected light in the optical path between the projected light and the reflected light In the reflection type optical sensor for detecting, the light projecting unit includes a first light emitting element that emits light of a certain wavelength, and a second light emitting element that emits light of a wavelength different from the first light emitting element, First and second
And a light combining means for synthesizing light emitted from the light emitting element of the first light emitting element, wherein the reflection plate has a characteristic that the reflectance with respect to the light emitted from the first light emitting element and the reflectance with respect to the light emitted from the second light emitting element differ. I have. According to a second aspect of the present invention, in the reflection-type photosensor according to the first aspect, one of light emitted from the first and second light emitting elements is transmitted and the other light is reflected, as the light combining means. A flat plate-shaped optical member synthesized by the above method is used. According to a third aspect of the present invention, in the reflection type optical sensor according to the second aspect, a dichroic mirror as a two-wavelength separation filter is used as the light combining means. According to a fourth aspect of the present invention, in the reflection type optical sensor according to the third aspect, the dichroic mirror is arranged in the divergent optical path. Claim 5
In the reflection type optical sensor according to any one of claims 1 to 3, the light emitting section alternately emits two light emitting elements, and the light receiving section receives light reflected from the reflector or the object by one light receiving element. To do. The invention of claim 6 relates to claims 1 to 3.
In the reflective optical sensor described above, the light receiving section includes a light separating unit that separates the light into two lights having different wavelengths, and at least two light receiving elements that respectively receive the two lights separated by the light separating unit. It is a thing. According to a seventh aspect of the present invention, in the reflection type optical sensor according to the first to third aspects, the light receiving section includes a color sensor having two sensitivities having different wavelengths. According to an eighth aspect of the present invention, in the reflection-type photosensor according to the second aspect, the flat plate-shaped optical member that constitutes the light synthesizing means is reflected on the surface on the side on which the light having the wavelength with the higher reflectance of the reflection plate is incident. A film is formed and an antireflection film is formed on the other surface. According to a ninth aspect of the present invention, in the reflection-type optical sensor according to the first to third aspects, the divergence angle of the emitted light of the wavelength having a higher reflectance at the reflecting plate in the light projecting portion is set to the output of the other wavelength. It is set to be smaller than the divergence angle of the emitted light. According to a tenth aspect of the present invention, in the reflective optical sensor according to the first to third aspects,
A light receiving element for monitoring the light emission output of the first and second light emitting elements is provided. According to an eleventh aspect of the present invention, in the reflection-type optical sensor according to the first to third aspects, the reflection plate is composed of a corner cube or an assembly of corner cubes. According to a twelfth aspect of the present invention, in the reflection-type photosensor according to any of the first to third aspects, the first and second light emitting elements respectively project light of two wavelengths, red light and infrared light, and the reflector is It is designed to absorb infrared light.
According to a thirteenth aspect of the present invention, in the reflection type optical sensor according to the first to third aspects, the light receiving section transmits the light in the wavelength band emitted by the first and second light emitting elements, and transmits the light in the other wavelength bands. It is equipped with a filter that reflects or absorbs.

[0006]

According to the reflection type optical sensor of the present invention, lights having different wavelengths are respectively emitted from the first and second light emitting elements, and the emitted lights are combined and projected onto the reflector or the object. It Since the reflection plate has characteristics that the reflectances with respect to the emitted lights of different wavelengths from the first and second light emitting elements are different, when the object shields the reflected light in the optical path of the projected light and the reflected light, The amount of reflected light of each wavelength received by the light receiving unit changes. The presence of the object can be detected by detecting the change in the reflected light amount.

[0007]

【Example】

(Embodiment 1) The configuration of Embodiment 1 of the present invention is shown in FIG. The optical sensor includes a light projecting section 1 and a light receiving section 2, two different lights are projected from the light projecting section 1 to the reflector 3, and the reflected light is received by the light receiving section 2. The light projecting unit 1 is provided with two light emitting elements 1a (wavelength λ1) and a light emitting element 1b (wavelength λ2) that emit light alternately and collimate each light by the light projecting lenses 5a and 5b. ), The two lights are combined by a dichroic mirror 6 having a characteristic of reflecting the light of wavelength λ1 and transmitting the light of wavelength λ2, and projecting the two lights toward the reflecting plate 3. The reflector 3 is shown in FIG.
As shown in (b), it has a characteristic of reflecting light of wavelength λ1 and absorbing light of wavelength λ2. Further, the light receiving section 2 is configured to receive the reflected light from the reflecting plate 3 via the light receiving lens 7 by the light receiving element 2a. When the detection object 8 enters the optical paths of the projected light and the reflected light, this is detected.

FIG. 3 shows a processing circuit of the signal obtained by the light receiving element 2a. The processing circuit is a main oscillation circuit, an oscillation circuit,
Amplifier, sample hold circuit (S / H), subtraction circuit,
It consists of an adder circuit, a comparator, and an AND circuit. This processing circuit synchronizes with the respective light emission signals of the two light emitting elements 1a and 1b to obtain the reflected light signals of the respective wavelengths.
The detection object 8 and the reflector 3 are discriminated by the difference and sum of the two reflected light amounts. The discriminant logic is as follows.

[0009]

[Table 1]

In FIG. 3, V1: received light signal of wavelength λ1, V2: received light signal of wavelength λ2 (which is absorbed by the reflector 3), Vth1: threshold value of the comparator 11 (there is no detection object 8) Case and a value between V1 and V2 when the detected object 8 is a mirror surface), Vth2: threshold value of the comparator 12 (a value slightly smaller than V1 + V2 when the detected object 8 is not present) output of the comparator 11: V1 -V2> Vth1 H output of comparator 12: H when V1 + V2> Vth2

Assuming that the projection power and the directivity of the wavelengths λ1 and λ2 are equal, if there is no detection object 8, the reflector 3
Since the component of the wavelength λ1 of the reflected light from is larger than the wavelength λ2, the output of the comparator 11 is H and the output of the comparator 12 is also H.
Therefore, it is determined that there is no detected object. Also, FIG.
As shown in, when the detection object 8'is a mirror surface or when there is a detection object with a high reflectance such as a white paper in a short distance, the wavelength λ
1, the amounts of reflected light of the wavelength λ2 are equal, the output of the comparator 11 becomes L, and it is determined that “there is a detected object”. On the other hand, in the case of a detection object having a low reflectance, the output of the comparator 12 becomes L regardless of the magnitude of the reflected light amount of the wavelengths λ1 and λ2 (the output of the comparator 11), and “there is a detection object” as in the conventional case. Determine.

Therefore, even when the detection object has a mirror surface characteristic like metal, and even when a detection object having a high reflectance such as white paper is in a short distance, there is a detection object depending on the amount of reflected light of two wavelengths. Since the discrimination can be made and the threshold value of the comparator 12 can be lowered, the installation distance of the reflection plate 3 can be made longer and the reflection plate 3 and the detection object 8 can be discriminated even if the amount of received light becomes small, and the long distance can be achieved. Can be achieved.

Another example of the processing circuit is shown in FIGS. FIG. 5 is a ratio (V1 / V2) of the amount of received light of wavelengths λ1 and λ2, and FIG.
Is detected by the difference / sum (V1−V2 / V1 + V2), and the same result as that of the above processing circuit can be obtained by comparing each with an appropriate threshold value. The wavelength selection of the two light emitting elements is generally 900 nm (infrared light) and 700
A combination of degrees (red light) is good. Further, since the green or blue detection object has a higher reflectance of infrared light than the red light, it is necessary for the reflector to have characteristics opposite to those of the detection object. Therefore, the wavelength of light reflected by the reflector may be 700 nm of red light. The dichroic mirror is formed with an optical multilayer film and has two characteristics: a characteristic of transmitting a long wavelength and a characteristic of reflecting a short wavelength, and a characteristic opposite thereto. If the number of film layers is about the same, the former has higher transmittance in the transmission wavelength region and higher reflectance in the reflection region, so that the characteristics of sharp rise of the boundary between transmission and reflection can be obtained. Therefore, performance,
It is desirable to use the former dichroic mirror in terms of cost.

(Embodiment 2) Embodiment 2 of the present invention is shown in FIG. Example 2 is a modification of the configuration of the light projecting unit 1 of Example 1, in which a dichroic mirror 6 is arranged in the divergent light path of the light emitted from the light emitting elements 1a and 1b, and two lights are combined, The light is projected onto the reflecting plate 3 via the light projecting lens 5. The transmittance and the reflectance of the dichroic mirror 6 at the wavelengths λ1 and λ2 are substantially constant in the incident angle range of the light incident on the light projecting lens 5. According to this configuration,
Compared to the first embodiment, one light projecting lens can be omitted,
It is possible to reduce the size and cost of the light projecting unit 1.

(Embodiment 3) Embodiment 3 of the present invention is shown in FIG. In the third embodiment, the two light emitting elements 1a and 1b of the light projecting unit 1 in the second embodiment are made to emit light at the same time, the light receiving unit 2 separates the light of two wavelengths by the dichroic mirror 9, and receives the light of each wavelength. The light is received by the elements 2a and 2b. The processing circuit of this embodiment is as shown in FIG.

(Embodiment 4) A fourth embodiment of the present invention will be described with reference to FIGS.
It shows in FIG. The fourth embodiment is the same as the second embodiment except that the light projecting unit 1 is used.
The two light emitting elements 1a and 1b are simultaneously made to emit light, and instead of the light receiving element 2a in the light receiving section 2, the color sensor 20 is used to receive light. The processing circuit shown in FIG. 11 is used, and the color sensor 20 having sensitivity peaks (PD-a, PD-b) at two wavelengths λ1 and λ2 as shown in FIG. 12 is used. Good.

(Fifth Embodiment) FIG. 13 shows a fifth embodiment of the present invention. The fifth embodiment is a dichroic mirror 6 of the light projecting unit 1.
It is characterized by the structure of. This dichroic mirror 6
Is an optical multi-layer film having a property of synthesizing wavelengths formed on the incident surface of the light of the light emitting element 1a having the wavelength λ1 reflected by the reflection plate (not shown). An antireflection film 6a (non-reflection coating) is formed on the incident surface of light of the light emitting element 1b of the wavelength λ2 to be absorbed (the rear surface of the surface of the substrate on which the optical multilayer film is provided).
When a parallel plate optical element (here, the dichroic mirror 6) is arranged in the divergent light path, the light transmitted through it has coma and astigmatism, and thus the intensity distribution of the projected beam is distorted. Therefore, when the light having the wavelength λ1 is reflected on the incident surface, the projected beam having the wavelength λ1 reflected and received by the reflection plate (not shown) is not distorted, so that a stable received light amount can be obtained. Further, since the antireflection film 6a is formed on the incident surface of the wavelength λ2, Fresnel reflection is prevented and the loss of projection power is reduced.

(Embodiment 6) Embodiment 6 of the present invention is shown in FIG. In the present embodiment, as shown in FIG. 14A, the sensor main body is so arranged that the projection beam of wavelength λ1 having the higher reflectance on the reflection plate 3 is included in the projection beams of the other wavelength λ2. The divergence angle of the projection beam of the 10 projection parts is designed. The optical axes and divergence angles of the projected light beams of two wavelengths vary due to the deviation of the outer shape of the light emitting element and the chip, the relative positional deviation of the light projecting lens and the two light emitting elements, and the angular deviation of the dichroic mirror. Occurs, and Fig. 1
As shown in FIG. 4 (b), a part where the two projected beams do not overlap occurs. When the reflecting plate is installed only in the range of wavelength λ1, and the mirror-like detection object 8 ′ is blocked between the sensor body 10 and the reflection plate 3, the light reflected by this detection object 8 ′ is reflected by the reflection plate 3. As in the case, only the wavelength λ1 is present, and the detection object 8 ′ cannot be detected. Therefore, in consideration of the variation in the case where there is a positional deviation in the above manufacturing, the projection beam of the wavelength λ1 is always included in the projection beam of the wavelength λ2 as shown in FIG. Design the divergence angle of the two projection beams.

That is, the divergence angle of the projection beam of the wavelength λ1 is θ1, the divergence angle of the projection beam of the wavelength absorbed by the reflector 3 is θ2, and the angular deviation between the optical axes of the wavelengths λ1 and λ2 is θ.
When d is set, the condition is such that (θ2 / 2)> (θ1 / 2) + θd. Therefore, there is no region in which only the projection beam of the wavelength λ1 exists, so that the detection object cannot be detected. FIG. 15 shows a configuration in which the divergence angles of the projection beams of wavelengths λ1 and λ2 are made different in the light projecting section. By making the optical path length between the light emitting element 1b having the wavelength λ2 and the light projecting lens 5 shorter than the optical path length between the light emitting element 1a having the wavelength λ1 and the light projecting lens 5, the wavelength λ
The divergence angle of the second projected beam can be made larger than the divergence angle of the projected beam of wavelength λ1.

(Embodiment 7) Embodiment 7 of the present invention is shown in FIG. Light emitting elements such as LEDs generally have different rates of change in luminous efficiency with temperature when the wavelengths are different. Therefore, when the ambient temperature changes, the ratio of the projection power of the two wavelengths changes, and the difference in the amount of received light of the two wavelengths in the light receiving unit changes, which may cause a malfunction. Therefore, in the seventh embodiment shown in FIG. 16, the wavelength λ1 as shown in FIG.
Of the light emitting element 1a using the dichroic mirror 6 having the characteristics that the transmittance of 5% and the transmittance of wavelength λ2 are 95%.
The transmitted light from and the reflected light from the light emitting element 1b are received by the light receiving element 21 for monitoring, and feedback is applied to each light emitting element according to the amount of each received light. FIG. 18 shows the processing circuit. By doing so, the light emission power can be stabilized and the above-mentioned malfunction can be prevented.

FIG. 19 shows another configuration example of the seventh embodiment. In this example, the dichroic mirror 6 shown in FIG.
As shown in 0, the incident angle θ1 that does not enter the projection lens 5
In the following, one having characteristics that the transmittance curve for wavelength λ1 is increased and the transmittance curve for wavelength λ2 is decreased, and the light from the light-emitting elements 1a and 1b is used in a range that does not enter the projection lens 5, respectively. The monitor light-receiving element 21 receives the transmitted and reflected light. According to this configuration, the loss of projection power is eliminated as compared with the configuration of FIG.

(Embodiment 8) FIG. 21 shows various configurations of the reflector 3 according to Embodiment 8. The reflector of this embodiment is based on an aggregate of corner cubes made of resin or glass. (A) is obtained by molding the corner cube 3a itself with a resin having a characteristic of absorbing the wavelength λ2.
In (b), a filter 3b that absorbs the wavelength λ2 is attached to the entrance surface of the corner cube 3a.
(C) shows an optical multilayer film 3c having the same characteristics as the dichroic mirror formed on the reflecting surface of the corner cube 3a. The absorber 3d prevents the light transmitted through the optical multilayer film 3c from returning to the corner cube again. Is provided. (D) is the optical multilayer film 3c on the reflecting surface as in (c).
And a member 3e having a surface for reflecting the light transmitted through the optical multilayer film 3c in a direction different from the light receiving portion so as not to return to the corner cube 3a again.

(Embodiment 9) An embodiment of the present invention is shown in FIGS. Some photoelectric sensors include a bandpass filter BPF that transmits only the wavelength band of the light emitting element 2a in the light receiving unit as a measure against ambient light. As shown in FIG. 23B, the conventional bandpass filter has a certain 1
It transmits only one wavelength band, and cannot be used for a sensor using two different wavelengths like this sensor. It is also possible to use a BPF that transmits all the bands including the wavelength bands of the two light emitting elements, but in that case,
It is not possible to cut the noise of the band component between the two wavelength bands,
S / N may not be sufficient.

Therefore, the above problem can be solved by using an optical filter having two wavelength transmission bands as shown in FIG. 23 (a). In FIG. 24, an optical filter BPF having the above-mentioned characteristic of having small incident angle dependency is arranged between the light receiving lens 7 and the light receiving element 2a. In addition, FIG.
An example in which the filter BPF is integrated with a light receiving element is shown in FIG. (A) of the figure is an example of a can type, and the light receiving element 2a
The optical filter BPF is used for the window of
(B) is an example of a resin mold type in which an optical filter BPF is attached in front of the light receiving element. Such integration can reduce the number of parts and the manufacturing process, and can reduce the cost.

FIG. 2 shows an example of the structure of the above optical filter BPF.
6 (a). The optical filter BPF is a transparent substrate 3
The optical multi-layered films 31 and 32 are formed on both surfaces of 0, and the optical multi-layered film 31 on one side has the wavelength band of the light emitting element 1a and the wavelength band of the light emitting element 1b as shown in FIG. The optical multi-layer film 32 on the other surface has one transmission band (characteristic 1) included therein and has a transmission band (characteristic 2) that transmits light having a wavelength other than the band between the bands of the two light emitting elements. It was formed in.

The present invention is not limited to the configuration of the above-described embodiment, but can be modified in various ways. In short, at least two light beams having different wavelengths λ1 and λ2 are projected onto a reflecting plate having a different reflectance depending on the wavelength, and the optical path thereof is changed. By utilizing the fact that the amount of reflected light received at each wavelength changes depending on whether or not there is a detection target object, it is to determine whether or not there is a detection target object. , P1 is the amount of light received at wavelength λ1 and P is the amount of light received at wavelength λ2 (which is absorbed by the reflector).
2, when P1> P2, there is no target object, P1
A determination method such that the target object is present when ≦ P2 is given, but the determination method is not limited to this.

[0027]

As described above, according to the reflection type optical sensor of the present invention, two light beams having different wavelengths are projected onto the reflection plate, and the reflection light beams from the reflection plate having different reflectances for the respective wavelengths of light. It is designed to distinguish between the reflector and the detection object based on the change in the amount of reflected light of each wavelength when the detection object intercepts the optical path. Even if you have
Since the reflected light amounts of the two wavelengths are almost equal to each other, it is possible to detect the presence of the detection object. Even when a high reflectance detection object such as a white paper is in a short distance, the presence of the detection object can be similarly detected. From the above, it is possible to distinguish the reflector and the detection object even if the amount of received light is reduced by increasing the installation distance of the reflection plate, so there is no malfunction for any detection object, and moreover,
A reflection type optical sensor capable of long-distance detection can be realized.

In addition to the above effects, particularly when a dichroic mirror for photosynthesis is arranged in the divergent optical path,
It is possible to reduce the size and cost of the light projecting unit. Further, in the dichroic mirror, a reflecting film is formed on the surface on the side where the light of the wavelength to be reflected by the reflecting plate is incident, and an antireflection film is formed on the surface on the side where the light of the wavelength to be transmitted is incident. Even in the case of arranging in the divergent light path, the projection beam is not distorted and the projection power loss is eliminated. Also, of the light emitted from the light projecting part, the divergence angle of the light of the wavelength having the higher reflectance on the reflecting plate is set to be smaller than the divergence angle of the light of the other wavelength, so that the former only Since there is no area, there is no possibility that an object cannot be detected. Moreover, malfunctions can be prevented by receiving the light emission output for light emission from the monitor and stabilizing the light emission power. Further, by providing a filter that allows light in the wavelength band emitted from the light emitting element to pass, there is an effect that a sufficient S / N can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a reflective photosensor according to a first embodiment of the present invention.

2A and 2B are characteristic diagrams of transmittance and reflectance of the dichroic mirror and the reflector used in Example 1. FIG.

FIG. 3 is a circuit diagram of a processing circuit of the reflective photosensor according to the first embodiment.

FIG. 4 is a diagram of a case where a detection object has a mirror surface characteristic in the reflective optical sensor.

FIG. 5 is a circuit diagram showing another example of a processing circuit.

FIG. 6 is a circuit diagram showing still another example of the processing circuit.

FIG. 7 is a configuration diagram of a reflective photosensor according to a second embodiment.

FIG. 8 is a configuration diagram of a reflective photosensor according to a third embodiment.

FIG. 9 is a circuit diagram of a processing circuit according to a third embodiment.

FIG. 10 is a configuration diagram of a reflective photosensor according to a fourth embodiment.

FIG. 11 is a circuit diagram of a processing circuit according to a fourth embodiment.

12A, 12B, and 12C are a cross-sectional view, a circuit diagram, and a characteristic diagram of a color sensor used in Example 4.

FIG. 13 is a configuration diagram of a light projecting unit of a reflective photosensor according to a fifth embodiment.

14A is a diagram showing a configuration of a reflective photosensor of Example 6, showing a case where no malfunction occurs, and FIG. 14B is a diagram showing a case where malfunction occurs.

FIG. 15 is a configuration diagram of a reflective photosensor according to a sixth embodiment.

FIG. 16 is a configuration diagram of a light projecting unit of a reflective photosensor according to a seventh embodiment.

FIG. 17 is a characteristic diagram of the transmittance of the dichroic mirror of Example 7.

FIG. 18 is a circuit diagram of a processing circuit according to a seventh embodiment.

FIG. 19 is a configuration diagram showing another example of the light projecting unit of the reflective photosensor of the seventh embodiment.

20 is a characteristic diagram of the transmittance of the dichroic mirror used in the example of FIG.

FIG. 21 is a diagram showing various examples of a reflector according to Example 8.

FIG. 22 is a configuration diagram of a light receiving portion of a reflective photosensor according to a ninth embodiment.

23A is a characteristic diagram of the optical filter used in Example 9, and FIG. 23B is a characteristic diagram of a conventional optical filter.

FIG. 24 is a configuration diagram showing another example of the light receiving unit of the reflective photosensor according to the ninth embodiment.

25A and 25B are a configuration diagram and a characteristic diagram of an optical filter.

26A and 26B are perspective views showing an example of integration of a light receiving element and an optical filter.

FIG. 27 is a configuration diagram of a conventional reflective photosensor.

[Explanation of symbols]

 1 Light emitting part 1a, 1b Light emitting element 2 Light receiving part 2a, 2b Light receiving element 3 Reflector 3a Corner cube 6 Dichroic mirror 8 Detecting object 20 Color sensor 21 Light receiving element for monitor BPF Optical filter

Claims (13)

[Claims] 1. A light projecting unit, a reflecting plate for reflecting light projected from the light projecting unit, and a light receiving unit for receiving reflected light from the reflecting plate or an object, and the light projecting unit and the reflected light. In the reflective optical sensor for detecting the object by detecting that the amount of reflected light received by the light receiving unit changes by blocking the reflected light by the object in the optical path of, A first light emitting element that emits light of a certain wavelength, a second light emitting element that emits light of a wavelength different from that of the first light emitting element, and light emitted from the first and second light emitting elements A light synthesizing means for synthesizing light, wherein the reflection plate has a characteristic in which the reflectance with respect to the light emitted from the first light emitting element and the reflectance with respect to the light emitted from the second light emitting element have different characteristics. Characteristic reflection type optical sensor. 2. The light combining means is a flat plate-shaped optical member that combines the light emitted from the first and second light emitting elements by transmitting one of the lights and reflecting the other light. The reflective optical sensor according to claim 1, wherein 3. The reflection type optical sensor according to claim 2, wherein the photosynthesis means is a dichroic mirror as a two-wavelength separation filter. 4. The reflective photosensor according to claim 3, wherein the dichroic mirror is arranged in a divergent optical path. 5. The light projecting section causes two light emitting elements to alternately emit light, and the light receiving section receives the reflected light from the reflector or the object with one light receiving element. The reflective optical sensor according to any one of 3 to 3. 6. The light receiving unit includes a light separating unit that separates the light into two lights having different wavelengths, and at least two light receiving elements that respectively receive the two lights separated by the light separating unit. The reflective optical sensor according to claim 1, wherein the reflective optical sensor is a reflective optical sensor. 7. The reflection type photosensor according to claim 1, wherein the light receiving unit includes a color sensor having two sensitivities having different wavelengths. 8. The flat plate-shaped optical member constituting the light combining means has a reflection film formed on the surface on the side on which light of the wavelength with the higher reflectance of the reflection plate is incident, and is reflected on the surface on the other side. The reflective optical sensor according to claim 2, wherein an anti-reflection film is formed. 9. The divergence angle of the emitted light of the wavelength having a higher reflectance at the reflection plate in the light projecting portion is set to be smaller than the divergence angle of the emitted light of the other wavelength. The reflection type optical sensor according to claim 1. 10. The reflection type photosensor according to claim 1, further comprising a light receiving element for monitoring the light emission output of the first and second light emitting elements. 11. The reflection-type photosensor according to claim 1, wherein the reflection plate is composed of a corner cube or an assembly of corner cubes. 12. The first and second light emitting elements respectively project light of two wavelengths, red light and infrared light, and the reflection plate absorbs infrared light. The reflection type optical sensor according to claim 1. 13. The light receiving unit includes a filter that transmits light in a wavelength band emitted by the first and second light emitting elements and reflects or absorbs light in other wavelength bands. The reflective optical sensor according to claim 1.