JP2003294414A - Optical fiber sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sensor adapted to various uses. <P>SOLUTION: A changeover switch 31 is changed over to a 'distance detection' side when a distance is detected. Whereupon, the light with the first wavelength and the light with the second wavelength projected from the first and second light projection elements 11 and 12 are guided to a light projection optical fiber 3 by a dichroic mirror 13. The light emitted from the light projection optical fiber 3 is again separated into the light with the first wavelength and the light with the second wavelength by a dichroic mirror 21. Further, when the sensor is desired to be utilized for a detection use other than the detection of a distance, the light projection optical fiber 3 and a light detection optical fiber 4 are drawn out of a sensor main body 1, and another detection head is connected to the sensor main body 1 to change over the changeover switch 31 to a 'detection' side. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical fiber sensor.

[0002]

2. Description of the Related Art Conventionally, a sensor for detecting a distance to an object to be detected by using an optical fiber has been known, and one of them is disclosed in Japanese Patent Laid-Open No. 2000-46516. This is because the sensor main body is provided with two light emitting elements and light receiving elements, and the light projecting light and the light receiving light are respectively received in the fiber insertion holes formed in the case of the sensor main body corresponding to these light projecting elements and light receiving elements. It has a configuration in which a fiber is inserted. Specifically, the operation is performed by arranging the tip of the light projecting optical fiber toward a region (detection region) in which the object to be detected can exist, and irradiating light from each light projecting optical fiber.
After that, after the reflected light from the predetermined position of the detected object is received by the light receiving optical fiber, the distance to the detected object is calculated by the sensor main body based on the received light amount of both reflected light.

[0003]

However, in the optical fiber sensor having the above-mentioned structure, the two kinds of light emitted from the sensor body are irradiated to the detection area by using different light projecting optical fibers. Therefore, a total of 3 optical fibers are required. This is because the structure is different from the conventional sensor body that is composed of two optical fibers.
A dedicated part such as a case having three fiber insertion holes must be used. Also, when arranging the light projecting and receiving optical fibers using a large number of optical fiber sensors,
There is a possibility that the degree of freedom in the installation will be limited.

The present invention has been made in view of the above circumstances, and an object thereof is to detect an distance to an object to be detected, but to provide an optical fiber sensor which can be constituted by two optical fibers. To provide.

As means for achieving the above object,
The invention of claim 1 comprises a sensor main body having two fiber insertion holes and a detection head provided with optical fibers for projecting and receiving light which can be attached to and detached from the fiber insertion holes. The light from the light source is guided to the detection head by the light projecting optical fiber, and the reflected light emitted from the detection head and reflected by the object to be detected is guided from the detection head to the sensor body through the light receiving optical fiber. The light receiving means provided in the sensor body is configured to receive light, and the light projecting means is configured to generate light of two different wavelengths, and the light from the light projecting means is a single light source. Separating means for guiding the light from the light projecting optical fiber to the detection head by the light projecting optical fiber and separating the light from the light projecting optical fiber according to the wavelength thereof, And a light projecting optical system for irradiating one of the light beams separated by the means to a far point of the region where the object to be detected may exist and the other to a near point, and the light receiving means is provided from the light receiving optical fiber. Receiving reflected light of each wavelength to output a light reception signal for each light of each wavelength, the sensor main body receives each wavelength from the light receiving means in accordance with the distance between the detection target and the detection head. It is characterized in that the distance detecting means that operates based on the ratio of the received light signal of the reflected light is provided.

According to a second aspect of the present invention, there is provided a sensor main body having two fiber insertion holes and a detection head provided with optical fibers for projecting and receiving light which can be attached to and detached from the fiber insertion holes. The light from the light source provided in the above is guided to the detection head by the light projecting optical fiber, and the reflected light emitted from the detection head and reflected by the object to be detected is passed from the detection head through the light receiving optical fiber to the sensor. The light source is guided to a main body and is received by a light receiving means provided in the sensor main body. The light source is configured to generate light of two different wavelengths, and the light from the light projecting means is emitted by the light emitting means. The light is guided to the detection head by an optical fiber to irradiate the region where the object to be detected is present, and the detection head has a different directional characteristic depending on the wavelength. There is provided a light-receiving optical system toward the other is a near point to the far point of the region where the object to be detected may be present,
The light combining means for combining the light from the light receiving optical system and the single light receiving optical fiber guide the light to the sensor body, and the light receiving means receives the reflected light of each wavelength from the light receiving optical fiber. A light receiving signal is output for each wavelength of light, and the sensor main body is based on the ratio of the light receiving signals of the reflected light of each wavelength from the light receiving means in accordance with the distance between the detected body and the detection head. The feature is that a distance detecting means that operates is provided.

According to a third aspect of the present invention, in the first or second aspect, the light receiving means is composed of one light receiving element, and the light receiving element has two types of wavelengths which are turned on by the light projecting means. It is characterized in that light is received for each of these two types of wavelengths and a light reception signal is output for each of the wavelengths of light in synchronism with the lighting timing of light.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the light projecting means includes first and second light projecting elements which emit lights having wavelengths different from each other.
It is characterized in that it comprises light combining means for guiding the light from these light projecting elements to the light entering end of the light projecting optical fiber.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the light receiving means is
A light separating means for separating the light from the light receiving optical fiber according to the wavelength and two light receiving elements, and the two kinds of light separated by the light separating means are respectively received by the light receiving elements, and these It is characterized in that the light receiving element outputs a light receiving signal of light of each wavelength.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the sensor main body is provided with an object detecting means that operates based on the light received by the light receiving means. At the same time, it is characterized in that selection means for selectively activating the object detection means and the distance detection means is provided.

The invention of claim 7 is characterized in that it is a detection head for constructing the optical fiber sensor of claim 1.

The invention of claim 8 is characterized in that it is a detection head for constructing the optical fiber sensor of claim 2.

[0013]

According to the present invention, the two kinds of light emitted from the light projecting means pass through a single optical fiber for projecting light and the detection head. After being separated into light of each wavelength by the light separating means, the light of one wavelength is irradiated by the light projecting optical system to the far point in the area (detection area) where the object to be detected can exist. , The other is radiated to the near point. Then, after the reflected light from the object to be detected is incident on the light receiving optical fiber and the reflected light of each wavelength is received by the light receiving means, the distance detecting means determines the distance between the object to be detected and the detection head. It operates based on the ratio of the received light signal of the reflected light of each wavelength output from the light receiving means.

Here, based on the ratio of the reflected light of each wavelength outputted from the light receiving means, specifically, when the object to be detected exists in the far point area side of the detection area, which is far from the detection head. , The reflected light based on the light of one wavelength applied to the far point area is received by the light receiving means more than the reflected light based on the light of the other wavelength applied to the near point area, and the detected object is detected. When it exists on the near point area side close to the detection head in the area, the reflected light based on the light of another wavelength emitted to the near point area is reflected based on the light of one wavelength emitted to the far point area. This means that more light is received by the light receiving means. That is, the received light signal of the reflected light of each wavelength output by the light receiving means changes depending on the position of the object to be detected, and accordingly, the ratio of the received light signals of the two reflected light changes. Works. The lights of two different wavelengths emitted from the light projecting means may be projected at the same time or may be projected alternately.

Thus, according to the first and sixth aspects of the invention, two types of light can be transmitted by one light projecting optical fiber, so that a total of two optical fibers can be used. .

<Inventions of Claims 2 and 8> In the present invention, the two kinds of light emitted from the light projecting means may pass through the optical fiber for projecting light and the object to be detected may exist from the detection head. The light receiving optical system irradiates the area (detection area), and the light of one wavelength of the reflected light from the far point of the detection area and the light of the other wavelength of the reflected light from the near point are unified. Is guided to the sensor main body by the light receiving optical fiber and is received by the light receiving means for each light of each wavelength. Then, the distance detecting means operates based on the ratio of the light receiving signals of the light of the respective wavelengths output from the light receiving means in accordance with the distance between the detected object and the detection head.

The term "based on the ratio of the received light signals output from the light receiving means" means that when the object to be detected is on the far point region side, the reflected light from the far point region is closer to the near point region. More light is reflected by the light receiving means than the reflected light from, and therefore more light of one wavelength is received by the light receiving means than light of other wavelengths. On the other hand, when the object to be detected is present on the near point area side, the reflected light from the near point area is received by the light receiving means more than the reflected light from the far point area. Is received by the light receiving means more than the light of one wavelength. That is, the light receiving amount of the reflected light of each wavelength received by the light receiving means changes depending on the position of the object to be detected, and along with this, the ratio of the received light signals of both reflected light changes, and the determining means Works. The lights of two different wavelengths emitted from the light projecting means may be projected at the same time or may be projected alternately.

Thus, according to the inventions of claims 2 and 7, two kinds of light can be transmitted by one light projecting optical fiber, so that a total of two optical fibers can be used. .

<Invention of Claim 3> By differentiating the lighting timings of light of two wavelengths and further enabling the light receiving signals from the light receiving elements in accordance with the respective lighting timings, one light receiving element can perform two operations. It is possible to distinguish between wavelengths of light. As a result, the number of parts of the sensor body can be minimized.

<Invention of Claim 4> Normally, since the light entrance end of the optical fiber is very small, it is necessary to direct the light projecting means to the light entrance end in order to enter the light there. There is. Here, for example, in the case where the light projecting means is composed of two light projecting elements which emit light of different wavelengths,
It is impossible to directly expose both light projecting elements to the light entering end of the projecting optical fiber. On the other hand, according to the third aspect of the invention, the light projected from the first and second light projecting elements is guided to the light entering end of the light projecting optical fiber by the light guiding means. The light from the light projecting element can be surely made incident on the light incident end of the light projecting optical fiber.

<Invention of Claim 5> In order to determine the distance to the object to be detected, first, in the area where the object to be detected can exist, a near point area near the detection head and a far point away from the detection head. Light of each wavelength is emitted toward the area, and the light reflected from the object to be detected among the light emitted toward both areas is received by the light receiving means. At this time, when the object to be detected is in the far point region, the reflected light of the light emitted toward the far point region is larger in amount than the reflected light of the light emitted toward the near point region. Thus, the light of one wavelength is received by the light receiving element more than the light of another wavelength. on the other hand,
When the object to be detected is present on the near point region side, the reflected light of the light emitted toward the near point region is received by the light receiving means more than the reflected light of the light emitted toward the far point region. Therefore, more light of other wavelengths is received by the light receiving means than light of one wavelength. Alternatively, the light of each wavelength is irradiated toward the region where the object to be detected may exist, and the light receiving unit receives the reflected light from the far point region and the reflected light from the near point region.
At this time, when the detected object exists on the far point area side,
The reflected light from the far point area is received by the light receiving means more than the reflected light from the near point area, and therefore, the light of one wavelength is received by the light receiving means more than the light of other wavelengths. . On the other hand, when the object to be detected is present on the near point area side, the reflected light from the near point area is received by the light receiving means more than the reflected light from the far point area. Is received by the light receiving means more than the light of one wavelength. That is, the amount of received light of each wavelength received by the light receiving means changes depending on the position of the object to be detected, and the ratio of the received light signals of the two reflected lights changes accordingly. To determine the distance. Here, for example, when one light receiving element is used as the light receiving means, even if light of both wavelengths is received at the same time, it is not possible to distinguish the amount of received light of each wavelength. Therefore, light of each wavelength is emitted alternately. The reflected light of each wavelength must be alternately received by the light receiving element. However, in such a method, it takes time until the distance detection means starts the distance detection after the light is first emitted from the light projecting element. Therefore, it is desirable that the light of both wavelengths can be received at the same time. On the other hand, in the invention of claim 4, the light from the light receiving optical fiber is separated by the light separating means according to the wavelength, and the light of each wavelength is simultaneously detected by the two light receiving elements. It is configured to be able to receive light. As a result, it becomes possible to emit light of each wavelength at the same time, thereby shortening the time until the start of distance discrimination.

<Invention of Claim 6> For example, when it is desired to detect the presence or absence of an object to be detected in the detection area, the light projecting and receiving optical fibers are pulled out from the sensor body to detect the object to be detected. After inserting the optical fiber led out of the detection head into the sensor main body, the selection means activates the detection means. Then, the detection means validates the light receiving signal from the light receiving element in accordance with the lighting timing of the light source, and operates based on the amount of light received by this light receiving element.
As a result, it is possible to detect the presence / absence of the object to be detected based on the amount of light received by the light receiving element that changes depending on the presence / absence of the object to be detected in the detection region.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION <First Embodiment> An embodiment of an optical fiber sensor according to the present invention will be described with reference to FIGS. As shown in FIG. 1, the optical fiber sensor includes a sensor body 1 and a detection head 2.
Both are connected via a light projecting optical fiber 3 and a light receiving optical fiber 22. Then, the detection head 2 is arranged so as to face an area (detection area) where the detected body can exist, and the distance from the detected body 10 to the detection head 2 is calculated.

The sensor main body 1 has a first light projecting element 11 and a second light projecting element 12 which project light of two different wavelengths as a light projecting means, and a first light projecting element 11 which transmits light of a first wavelength. A well-known dichroic mirror 13 (corresponding to the light guiding means described in the claims) that reflects light of two wavelengths, and an optical fiber 4 for receiving light.
And a first light receiving element 14 (corresponding to a light receiving unit) that receives light from. The wavelength of the light emitted from the first light projecting element is the first wavelength, and the wavelength of the light emitted from the second light projecting element is the second wavelength.

The light projected from the first light projecting element 11 passes through the dichroic mirror 13 and enters the light entering end of the light projecting optical fiber 3, while the light projected from the second light projecting element 12 is projected. The light is reflected by the dichroic mirror 13 and is incident on the light incident end of the light projecting optical fiber 3.

From the side surface of the detection head 2, the ends of the light projecting optical fiber 3 and the light receiving optical fiber 4 are introduced. Further, inside the detection head 2, the dichroic mirror 21 that transmits the light of the first wavelength and reflects the light of the second wavelength among the light from the light projecting optical fiber 3 and the light of the second wavelength are reflected. A reflecting mirror 22, a lens 23 that irradiates a region (far point region) apart from the detection head 2 with the light of the first wavelength, and a region of the detection region near the detection head 2 with the light of the second wavelength. Lens 24 for irradiating (near point region)
And a lens 25 that receives reflected light from the object to be detected. The irradiation beams from both lenses 24 and 25 are designed to partially overlap each other. Of the light from the light projecting optical fiber 3, the light of the first wavelength is the dichroic mirror 2
The light of the second wavelength is guided through the lens 23 to the lens 23 and is emitted toward the far point region.
1 is reflected by the reflection mirror 22 and guided to the lens 24,
The light is emitted from here toward the near point region. Therefore, the dichroic mirror 21 and the reflection mirror 22 compose the light separating means described in the claims, and the lens 23 and the lens 24 compose the projection optical system described in the claims.

The housing of the sensor body 1 is provided with a changeover switch 31 (corresponding to the selecting means recited in the claims). By changing over the changeover switch 31, the changeover state is transmitted to the CPU 32. It is like this. In the CPU 32, when the changeover switch 31 is switched to the "distance determination" side, the "distance determination mode" (described later) for calculating the distance of the detected object 10 is set, and when it is switched to the "detection" side, the presence or absence of the detected object 10 is detected. Is switched to the “detection mode”, and the operation state in each operation mode is displayed on the display unit 33. Further, a first light projecting circuit 34 that supplies a drive current to the first light projecting element 11 and a second light projecting circuit 35 that supplies a drive current to the second light projecting element 12 to the CPU 32, and the first light receiving element 1
4 is connected to the first light receiving circuit 36 which receives the electrical signal from the signal line 4.

The detection operation of the optical fiber sensor having the above structure will be described. <Distance Discrimination Mode> When it is desired to detect the distance to the detected object 10, the changeover switch 31 is switched to “distance discrimination”. Then, the CPU 32 switches to the "distance detection mode" and transmits the light emitting timing signals having different phases to the first light emitting circuit 34 and the second light emitting circuit 35 to pulse-light the first and second light emitting elements. At the same time, the level of the light receiving signal output from the first light receiving circuit 36 in synchronization with the light projecting timing of the first light projecting element 11, that is, the level of the light receiving signal based on the reflected light from the far point region is received as the first light receiving. The level of the light reception signal stored as the level L1 and output from the light receiving circuit 36 in synchronization with the light projection timing of the second light projecting element 12, that is, the level of the light reception signal based on the light reflected from the near point area is the second level. The light receiving level L2 is stored. Then, the ratio (L1 / L2) of the two is obtained, and the distance is calculated based on the data indicating the relationship between the ratio (L1 / L2) of both light receiving levels and the distance to the detection object 10 which is stored in advance. Display 3
The distance is displayed on 3.

<Detection Mode> On the other hand, for example, when it is desired to detect the presence or absence of the object 10 to be detected in the detection area, first, the light projecting optical fiber 3 and the light receiving optical fiber 4 are pulled out from the sensor body 1. Then, a so-called reflection type detection head (not shown) provided with a light projecting unit that projects light toward the detection region and a light receiving unit that receives light from the light projecting unit reflected by the detection target 10 are provided. Is connected to the sensor main body 1 through the light emitting and receiving optical fibers. After that, the changeover switch 31 is changed over to the "detection" side. Then, the CPU 32
Switches to the "detection mode", transmits the light emission timing signals having different phases to the first light projecting element 11 and the second light projecting element 12, and synchronizes with the light projecting timing of the first light projecting element 11. The light receiving signal output from the first light receiving circuit 36 is received. Then, the light receiving level of the light receiving signal is compared with a preset reference level to detect the presence or absence of the detected object 10, and the detection state is displayed on the display unit 33.
Therefore, the CPU 32 functions as a distance detecting means and an object detecting means.

According to the optical fiber sensor of this embodiment,
A single optical fiber 3 for projecting light of the first and second wavelengths projected from the first projecting element 11 and the second projecting element 12 provided in the sensor body 1 by the dichroic mirror 13.
To the detection head 2 and then to the detection head 2
Then, the light of the first and second wavelengths is separated by the dichroic mirror 21 and emitted to the far point region and the near point region, respectively. As a result, only one light projecting optical fiber 3 is required, and only two fiber insertion holes are provided in the case of the sensor body 1. Therefore, it is not necessary to provide the case exclusively because the case formed with the two fiber insertion holes conventionally used can be used. Further, since the CPU 32 is configured to be switched between the "distance determination mode" and the "detection mode" by switching the changeover switch 31, the light projecting optical fiber 3 and the light receiving optical fiber 4 are removed and another detecting head is connected. As a result, it can be used for detection purposes other than distance detection, and therefore, the versatility of the sensor main body 1 can be enhanced.

<Second Embodiment> A second embodiment of the optical fiber sensor according to the present invention will be described with reference to FIG.
The same parts as those in the first embodiment are designated by the same reference numerals, duplicate description thereof will be omitted, and further, the same operation and effect will be omitted. In this embodiment, the internal structure of the detection head 2 is different from that of the detection head 2 of the first embodiment. That is, the end portion of the light projecting optical fiber 3 has a patch shape in which the end portion is divided into two hands, and the respective tip portions are set toward the lenses 23 and 24. Further, a first filter 26 that transmits light of the first wavelength is disposed between the lens 23 and one of the light projecting optical fiber 3 tips, and the lens 24 and the other light projecting optical fiber 3 tip portion. A second filter 27 that transmits light of the second wavelength is disposed between and. This allows
The light of the first wavelength emitted from the light projecting optical fiber 3 passes through the first filter 26 and is emitted from the lens 23 toward the far point region, and the light of the second wavelength passes through the second filter 27 and passes through the lens. The light is emitted from 24 toward the near point region. Therefore,
The lenses 23 and 24 compose the light separating means described in the claims, and the first filter 26 and the second filter 27 compose the projection optical system described in the claims.

<Third Embodiment> An embodiment of the optical fiber sensor according to the present invention will be described with reference to FIG.
The same parts as those of the embodiment are designated by the same reference numerals, and the overlapping description will be omitted, and the description of the same operation and effect will also be omitted.

On one side surface of the detection head 5, the lens 5 for emitting the light from the light projecting optical fiber 3 toward the detection region.
1, a lens 52 that is sensitive to light from the far point region side of the detection region, and a lens 53 that is sensitive to light from the near point region side. On the other hand, inside the detection head 5, a first filter 54 that transmits the light of the first wavelength of the light from the lens 52 and a second filter 55 that transmits the light of the second wavelength of the light from the lens 53. Equipped with. Further, the light-receiving optical fiber 4 has a patch shape in which the end portion is divided into two hands, and the tip end portion thereof is provided with both filters 5.
It is set up facing 4,55.

Of the reflected light from the far point area toward the lens 52, the light of the first wavelength passes through the first filter 54 and enters the light receiving optical fiber 4, and is reflected from the near point area toward the lens 53. Of the light, the light of the second wavelength is the second filter 55.
And is incident on the light-receiving optical fiber 4. Therefore, the lenses 51 and 52, the first filter 54 and the second filter 5
5 functions as the light receiving optical system described in the claims.

<Fourth Embodiment> A fourth embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the dichroic mirror 15 for separating the light of the first wavelength and the light of the second wavelength out of the light from the light receiving optical fiber 4 in the sensor body 1 (the light of the claim) (Corresponding to a separating means), the dichroic mirror 15 and the first
A second light receiving element 16 that receives the light of the second wavelength that constitutes the light receiving means together with the light receiving element 14 is additionally provided.
Further, regarding the electrical configuration, the second light receiving circuit 37 that receives the electric signal from the second light receiving element 16 is connected to the CPU 32.

The operation of the optical fiber sensor having the above structure will be described below. When it is desired to detect the distance to the detected object 10, the changeover switch 31 is switched to the "distance determination" side. Then, the CPU 32 causes the "distance determination mode".
To the first light projecting element 11 and the second light projecting element 11 and transmit the light projecting timing signals of the same phase to each other, and in synchronization with the light projecting timing signal, the first light receiving circuit 3
The light receiving signal output from 6 and the light receiving signal output from the second light receiving circuit 37 are simultaneously received. Then, the light receiving level of the light receiving signal from the first light receiving circuit 36 is set to the first light receiving level L.
1 and the light receiving level of the light receiving signal from the second light receiving circuit 37 is set as the second light receiving level L2, and the ratio of both (L1 / L2)
Then, the ratio of both light receiving levels set in advance (L1 /
The distance is calculated based on the data indicating the relationship between L2) and the distance to the detected object 10, and the distance is displayed on the display unit 33. Further, in order to detect the presence or absence of the detected body 10 as in the first embodiment, the detection head 2 is replaced with another detection head and the changeover switch is switched to the "detection" side. Then,
The CPU 32 switches to the “detection mode”, transmits a light projecting timing signal to the first light projecting circuit 34, and receives a light receiving signal from the first light receiving circuit in synchronization with the light projecting timing of the first light projecting element 11. receive. Then, the light reception level of the light reception signal is compared with a preset reference level to detect the presence or absence of the detected object 10, and the detection state is displayed.
To display.

As a result, light of each wavelength can be emitted at the same time and reflected light from the far point region and the near point region can be received at the same time, so that the operation cycle of the discriminating means can be shortened. In the case of determining the distance of the detection object whose moving speed is fast, the distance can be determined more accurately.

<Fifth Embodiment> In this embodiment, as shown in FIG. 7, the sensor body 1 of the second embodiment has the same structure as that of the fourth embodiment.

<Sixth Embodiment> This embodiment is as shown in FIG. 8, and the sensor main body 1 in the third embodiment has the same structure as that of the fourth embodiment.

<Other Embodiments> The present invention is not limited to the above-described embodiments, and for example, the embodiments described below are also included in the technical scope of the present invention.
Other than the following, various modifications can be made without departing from the scope of the invention. (1) In the above embodiment, the ratio between the first light receiving level L1 and the second light receiving level L2 is “L1 / L2”, but it may be the opposite “L2 / L1”. In this case, the data indicating the relationship between the preset light receiving level ratio and the distance to the detected object is the light receiving level ratio (L2 / L1).
It is data showing the relationship between the distance and the distance.

(2) Further, the first light projecting element 11 and the second light projecting element 12 are used to project light of two kinds of wavelengths, and the dichroic mirror 13 projects these lights with the optical fiber 3 for projecting. However, it is also possible to project light of two different wavelengths using, for example, a light emitting diode having a chip that emits light of two wavelengths traveling in the same direction. In this case, since the lights of both wavelengths travel in the same direction, the dichroic mirror 1 is arranged by facing the light receiving end of the light projecting optical fiber.
3 can be omitted.

(3) In the first to third embodiments, when the CPU 32 is in the "detection mode", the first
Although the light projecting timing signals having different phases are transmitted to the light projecting circuit 34 and the second light projecting circuit 35, the light projecting timing signal may be transmitted to either one of the light projecting circuits. Alternatively, the light emission timing signals having the same phase as each other may be transmitted.

(4) Further, the light of the first wavelength is emitted toward the far point region and the light of the second wavelength is emitted toward the near point region. In other words, the point is that light can be emitted to the far point region and the near point region.

(5) In the fourth to sixth embodiments, when the CPU 32 is in the "detection mode", the light projecting timing signal is transmitted to the first light projecting circuit 34. The light emitting timing signals may be transmitted to the optical circuits 34 and 35 in the same phase or in different phases, and at this time, one of the first light receiving circuit 36 and the second light receiving circuit 37 receives light. It is sufficient to validate the received light signal of.

(6) Further, the light of the first wavelength is incident on the lens 51 which is sensitive to the reflected light from the far point region, and the light of the second wavelength is sensitive to the reflected light from the near point region. Although the configuration is such that the light enters the lens 52 having the above, it may be the opposite.

(7) Further, although the first light receiving element 14 receives the light of the first wavelength and the second light receiving element 16 receives the light of the second wavelength, the reverse is also possible.

[Brief description of drawings]

FIG. 1 is an overall view of an optical fiber sensor according to a first embodiment.

FIG. 2 is a diagram showing an electrical configuration of a sensor body.

FIG. 3 is an overall view of an optical fiber sensor according to a second embodiment.

FIG. 4 is an overall view of an optical fiber sensor according to a third embodiment.

FIG. 5 is an overall view of an optical fiber sensor according to a fourth embodiment.

FIG. 6 is a diagram showing an electrical configuration of a sensor body.

FIG. 7 is an overall view of an optical fiber sensor according to a fifth embodiment.

FIG. 8 is an overall view of an optical fiber sensor according to a sixth embodiment.

[Explanation of symbols]

1 ... Sensor body 2 ... Detection head 3 ... Optical fiber for projection 4 ... Optical fiber for receiving light 11 ... First light projecting element 12 ... Second light projecting element 13 ... dichroic mirror 14 ... Light receiving element 21 ... dichroic mirror 22 ... Reflective mirror 23, 24, 25 ... Lens 31 ... Changeover switch 32 ... CPU 33 ... Display

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Claims (8)

[Claims] 1. A light emitting device provided on the sensor body, comprising a sensor body having two fiber insertion holes and a detection head having detachable optical fibers for projecting light and receiving light in the fiber insertion hole. The light from the means is guided to the detection head by the light projecting optical fiber, and the reflected light emitted from the detection head and reflected by the object to be detected is guided from the detection head to the sensor body through the light receiving optical fiber. The light receiving means provided in the sensor main body receives the light, and the light projecting means is configured to generate light of two different wavelengths, and the light from the light projecting means is a single light source. While guiding to the detection head with the light projecting optical fiber,
The detection head has a separating means for separating the light from the light projecting optical fiber according to the wavelength thereof, and one of the light separated by the separating means is a far end of a region in which an object to be detected can exist. The point is provided with a light projecting optical system for irradiating the other point to the near point, and the light receiving means receives the reflected light of each wavelength from the light receiving optical fiber and outputs a light receiving signal for each light of each wavelength, The sensor body is provided with a distance detecting means that operates based on a ratio of received light signals of reflected light of each wavelength from the light receiving means according to a distance between the detected body and the detection head. And an optical fiber sensor. 2. A sensor main body having two fiber insertion holes, and a detection head having optical fibers for projecting and receiving light which can be attached to and detached from the fiber insertion holes, and a light source provided in the sensor main body. The light of the above is guided to the detection head by the light projecting optical fiber, and the reflected light that is emitted from the detection head and reflected by the object to be detected is guided from the detection head to the sensor body through the light receiving optical fiber, In the light receiving means provided in the sensor body, the light source is configured to generate light of two different wavelengths, and the light from the light projecting means is transmitted to the light projecting optical fiber. And directs it to the detection head to irradiate the area where the object to be detected is present, and the detection head has different directional characteristics depending on the wavelength, and one of the objects is the object to be detected. A light receiving optical system in which the other point toward the near point is provided at the far point in the possible area, and the sensor main body is provided with the light combining means for combining light from the light receiving optical system and the single light receiving optical fiber. The light receiving means receives reflected light of each wavelength from the light receiving optical fiber and outputs a light reception signal for each light of each wavelength, and the sensor main body is provided between the detected body and the detection head. An optical fiber sensor comprising distance detecting means that operates based on the ratio of the received light signals of the reflected light of each wavelength from the light receiving means according to the distance. 3. The light receiving means is composed of one light receiving element, and the light receiving element synchronizes with a lighting timing of light of two kinds of wavelengths to be turned on by the light projecting means, and outputs the light of the two kinds of wavelengths. The light-receiving signal is received for each light, and a light-receiving signal is output for each light of each wavelength.
The optical fiber sensor described in 1. 4. The light projecting means includes first and second light projecting elements for emitting lights having wavelengths different from each other, and light from these light projecting elements to a light incident end of the light projecting optical fiber. 4. The optical fiber sensor according to claim 1, further comprising a light synthesizing means for guiding. 5. The light receiving means comprises a light separating means for separating the light from the light receiving optical fiber according to the wavelength, and two light receiving elements, and two kinds of light separated by the light separating means are provided. 5. The optical fiber sensor according to claim 1, wherein each of the light receiving elements receives the light, and the light receiving signals of the light of each wavelength are output from these light receiving elements. 6. The sensor main body is provided with an object detecting means that operates based on the amount of light received by the light receiving means, and a selecting means that selectively enables the object detecting means and the distance detecting means. The optical fiber sensor according to any one of claims 1 to 5, further comprising: 7. A detection head constituting the optical fiber sensor according to claim 1. 8. A detection head constituting the optical fiber sensor according to claim 2.