JP2000065654A - Optical fiber touch sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of the optical fiber of an optical fiber touch sensor. SOLUTION: In the touch detecting section 10A of an optical fiber touch sensor 10, the conventional cladding section is not formed in the outer peripheral section of an optical fiber 12 except the contacting section of the fiber 12 with a bridge 34 and the air plays the role of the cladding section. In addition, a rubber cover 30 is put around the fiber 12 and the inner peripheral surface of the cover 30 is colored in black. Therefore, when the inner peripheral surface of the cover 30 comes into contact with the outer peripheral surface of the fiber 12, the quantity of transmitted light abruptly decreases even when the optical fiber 12 is not deformed, because a large quantity of light is absorbed from the contacting section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber touch sensor, and more particularly to an optical fiber touch sensor for detecting contact with another member based on a decrease in the amount of light transmitted through an optical fiber.

[0002]

2. Description of the Related Art Conventionally, an electric motor is disposed on an outer peripheral portion of an automobile body.
An example of an optical fiber touch sensor for detecting contact with another vehicle is disclosed in Japanese Patent Application Laid-Open No. 5-116592.

As shown in FIG. 12A, in this optical fiber touch sensor, an optical fiber in which a core 72 made of a high-refractive-index silicone rubber and a clad 74 made of a low-refractive-index silicone rubber are covered with a fluorine-based rubber 76 is used. 70 is used.

As shown in FIG. 12B, in this optical fiber touch sensor 78, an optical fiber 70 is inserted into a flexible cylindrical base 80 formed in a tubular shape. When an external force (arrow F in FIG. 12 (B)) is applied, an inner peripheral portion of the cylindrical base portion 80 is formed.
The optical fiber 70 is locally bent and deformed by the projection 82 and the projection 84 facing each other. As a result, the condition of total reflection of the optical fiber 20 is broken, and the amount of transmitted light is extremely reduced. By detecting the decrease in the amount of light, contact with another vehicle is detected.

[0005]

However, in this optical fiber touch sensor 78, in order to detect contact with another vehicle, the optical fibers 7 are formed by the projections 82 and 84.
Since it is necessary to forcibly bend and deform 0, the optical fiber 70 is easily deteriorated and has poor durability.

An object of the present invention is to provide an optical fiber touch sensor capable of improving the durability of an optical fiber in consideration of the above fact.

[0007]

According to a first aspect of the present invention, there is provided an optical fiber touch sensor according to the first aspect of the present invention, wherein the optical fiber has an uncladded optical fiber, a light emitting portion disposed at one end of the optical fiber, and the optical fiber. A light receiving unit disposed at the other end of the optical fiber, and a light absorbing unit disposed at an outer peripheral portion of the optical fiber and absorbing a part of the transmission light by contacting the optical fiber. I do.

Accordingly, when the light absorbing means is deformed by an external force caused by contact with another member and the light absorbing means comes into contact with the surface of the optical fiber, a part of the light transmitted from the light emitting portion to the light receiving portion is absorbed at the contact portion. In this case, the amount of light detected by the light receiving unit is extremely reduced. That is, when the light absorbing means comes into contact with the surface of the optical fiber, contact with another member can be detected. As a result, the load on the optical fiber can be reduced as compared with the related art in which the optical fiber is deformed, so that the durability of the optical fiber can be improved.

According to a second aspect of the present invention, in the optical fiber touch sensor according to the first aspect, the light absorbing means is an elastic body whose inner peripheral surface has a light absorbing color.

Therefore, in addition to the contents of the first aspect, by making the inner peripheral surface of the light absorbing means a light absorbing color, the transmission loss of the optical fiber due to contact with the light absorbing means increases, and the detection accuracy is improved. I do. Further, when the inner peripheral surface of the light absorbing means comes into contact with the surface of the optical fiber, the contact area of the light absorbing means with the optical fiber is elastically deformed, thereby increasing the contact area between the light absorbing means and the optical fiber. For this reason, transmission loss increases and detection accuracy improves. Further, when the external force is removed, the light absorbing means returns to its original shape, so that there is no need to repair and replace the light absorbing means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an optical fiber touch sensor according to the present invention will be described with reference to FIGS.

As shown in FIG. 5, the touch detecting section 10A of the optical fiber touch sensor 10 of the present embodiment is provided at the outer periphery of the vehicle body 14, in the present embodiment, the front bumper 14 is provided.
A, the side door 14B, the rear bumper 14C and the like are stretched in a loop.

As shown in FIG. 1, the touch detecting section 10A of the optical fiber touch sensor 10 includes an optical fiber 12
It has.

As shown in FIG. 4, both ends 12A and 12B of the optical fiber 12 are inserted into the vehicle body 14, and one end 12A serves as a light emitting unit for transmitting light to the optical fiber 12. LED 16 is connected. Also, at the other end 12B of the optical fiber 12,
A photodiode 18 is connected as a light receiving unit that receives light transmitted through the optical fiber 12 and converts the light into an electric signal.

The LED 16 and the photodiode 1
Reference numeral 8 is connected to a control unit 20, to which a well-known acceleration sensor 22 for detecting a collision of the vehicle body is connected. The control unit 20 includes a driver airbag device 26 as a well-known safety device disposed on the steering 26.
Is connected. Therefore, the control unit 20
In the air bag device 26, based on a detection signal from the acceleration sensor 22 generated at the time of a collision with another vehicle or the like,
When the airbag device 26 is operated, the operation threshold value is changed based on an input signal from the optical fiber touch sensor 10 to reliably operate the airbag device 26.

As shown in FIG. 1, in the touch detecting section 10A of the optical fiber touch sensor 10, a cover 30 is provided as a light absorbing means with a predetermined space opened (non-contact) around the optical fiber 12. ing. The cover 30 is made of rubber as an elastic body, the inner peripheral surface 30A is black as a light absorbing color, and the upper portion is thick.

As shown in FIG. 2, the cover 30 has an opening on the vehicle body side, and flanges 30C and 30D are formed at both ends of the opening 30B so as to extend outward from the opening 30B. On the other hand, a resin base 32 is fixed to the vehicle body 14 with an adhesive tape 33 or the like. This base 32
, An opening 32A is formed outward, and flanges 32B, 32C are formed at both ends of the opening 32A toward the inside of the opening 32A. Accordingly, by engaging the flanges 30C and 30D of the cover 30 with the insides of the flanges 32B and 32C of the base 32, the cover 30
Can be attached to the base 32.

A base 32D is provided on the bottom 32D of the base 32.
The bridges 34 are integrally formed at predetermined intervals along the longitudinal direction of the bridge. A through hole 36 is provided in the upper part of the bridge 34.
The optical fiber 1 is inserted into the through hole 36.
2 has been inserted. The bridge 34 has an optical fiber assembling slit 35 communicating with the through hole 36. Further, at the outer peripheral portion of the optical fiber 12 which is to be in contact with the bridge 34, there is formed a grad portion 38 whose refractive index is set to be lower than the refractive index of the optical fiber 12. , So that light is not absorbed.

That is, as shown in FIG. 6, in the present embodiment, no conventional glad portion is formed on the outer peripheral portion of the optical fiber 12 except for the contact portion with the bridge, and the atmosphere serves as the glad. I have. As a result, the loss light L1 of the transmitted light L is slightly increased as compared with the case where there is a grad portion. However, as shown in FIG. 7, when the inner peripheral surface 30 </ b> A of the cover 30, which is black as the absorption color, comes into contact with the outer peripheral portion of the optical fiber 12, a large amount of light L <b> 2 is absorbed from the contact portion. , Inner peripheral surface 30A of cover 30
As shown in FIG. 8, the amount of transmitted light rapidly decreases with an increase in the contact area S between the optical fiber 12 and the outer peripheral portion of the optical fiber 12. As a result, it is possible to detect contact with the touch detection unit 10A of another vehicle or the like with high sensitivity without applying too much load to the optical fiber 12.

Next, the operation of the present embodiment will be described.

In the present embodiment, as shown in FIG. 3, the cover 30 is elastically deformed by an external force (arrow F in FIG. 3) due to contact with another vehicle or the like, and the inner peripheral surface 30A of the cover 30 is blackened. When light comes into contact with the surface of the optical fiber 12, even if the optical fiber 12 is not deformed, a part of the transmitted light is absorbed from the contact portion and transmission loss is increased, and the photodiode 1
The amount of light detected at 8 is extremely reduced. That is, the contact between the inner peripheral surface 30A of the cover 30 and the outer peripheral portion of the optical fiber 12 can detect contact with another vehicle or the like. As a result, the load on the optical fiber can be reduced as compared with the related art in which the optical fiber is deformed, so that the durability of the optical fiber 12 can be improved.

In this embodiment, since the cover 30 is formed of rubber as an elastic body, the inner peripheral surface 3 of the cover 30 is formed.
When 0A comes into contact with the surface of the optical fiber 12, the contact area between the cover 30 and the optical fiber 12 is elastically deformed, so that the contact area between the cover 30 and the optical fiber 12 is increased. For this reason, transmission loss increases and detection accuracy improves. Further, when the external force is removed, the cover 30 that has been elastically deformed returns to its original shape, so that there is no need to repair and replace the cover 30.

Next, a second embodiment of the optical fiber touch sensor according to the present invention will be described with reference to FIGS.

The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 9, in the present embodiment, the cover 40 as the light absorbing means has a tubular shape, and the optical fiber 12 is inserted into the cover 40. The cover 40 is formed of rubber as an elastic body, and the inner peripheral surface 40A is black as a light absorbing color.

As shown in FIG. 10, the cover 40 has
Along the longitudinal direction of the cover 40, a ring-shaped concave bridge 40B is integrally formed on the inner peripheral side at a predetermined interval. The optical fiber 12 is inserted through the center of the bridge 40B. In addition, the outer peripheral portion of the optical fiber 12 which is the contact portion with the bridge 40B is formed with a gladd portion 38 so that light is not absorbed by the contact with the bridge 40B.

In the present embodiment, a groove 44 having a C-shaped cross section is formed in the outer plate 42 of the vehicle body. The detection unit 10A can be attached to a vehicle body.

Next, the operation of the present embodiment will be described.

In the present embodiment, as shown in FIG.
Due to external force (arrow F in FIG. 11) due to contact with other vehicles, etc.
When the cover 40 is elastically deformed and the inner peripheral surface 40A of the black cover 40 comes into contact with the surface of the optical fiber 12, even if the optical fiber 12 is not deformed, a part of the transmitted light is absorbed from the contact portion and transmission loss is reduced. And the amount of light detected by the photodiode is extremely reduced. That is, the contact between the inner peripheral surface 40A of the cover 40 and the outer peripheral portion of the optical fiber 12 can detect contact with another vehicle. As a result, the load on the optical fiber can be reduced as compared with the related art in which the optical fiber is deformed, so that the durability of the optical fiber 12 can be improved.

In this embodiment, since the cover 40 is formed of rubber as an elastic body, the inner peripheral surface 4 of the cover 40 is formed.
When 0A comes into contact with the surface of the optical fiber 12, the contact area between the cover 40 and the optical fiber 12 is elastically deformed, so that the contact area between the cover 40 and the optical fiber 12 is increased. For this reason, transmission loss increases and detection accuracy improves. Further, when the external force is removed, the cover 40 that has been elastically deformed returns to its original shape, so that there is no need to repair and replace the cover 40.

The cover 40 can also prevent the transmission light from decreasing with time due to dust or the like adhering to the optical fiber surface.

In the above, the present invention has been described in detail with respect to a specific embodiment. However, the present invention is not limited to such an embodiment, and various other embodiments are included in the scope of the present invention. It is clear to a person skilled in the art that is possible. For example, the light emitting unit is not limited to the LED 16, but may be another light emitting body such as a lamp. Further, the light receiving section is not limited to the photodiode 18 and may be another light receiving element. Further, the safety device is not limited to the driver's seat airbag device 26, but may be another airbag device for a passenger seat or another safety device such as a pretensioner. The elastic body is not limited to rubber, but may be another elastic body such as a soft resin. Further, the light absorption color is not limited to black, but may be another dark color. Also,
A configuration in which a plurality of optical fiber touch sensors 10 are provided in one vehicle body may be adopted. Further, the present invention can be used as a general touch sensor other than for a vehicle.

[0033]

According to the first aspect of the present invention, there is provided an optical fiber touch sensor according to the present invention, comprising: an uncladded optical fiber having an atmosphere as a clad; a light emitting portion disposed at one end of the optical fiber; A light receiving unit provided, and a light absorbing unit provided on an outer peripheral portion of the optical fiber and absorbing a part of the transmission light by contacting the optical fiber,
Has an excellent effect that durability can be improved.

According to a second aspect of the present invention, in the optical fiber touch sensor according to the first aspect, the light absorbing means is an elastic body whose inner peripheral surface is a light absorbing color. In addition, there is an excellent effect that the detection accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view, partially in section, showing a main part of an optical fiber touch sensor according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view with a partial cross section showing a main part of the optical fiber touch sensor according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of an operation of the optical fiber touch sensor according to the first embodiment of the present invention.

FIG. 4 is a schematic plan view showing a vehicle body to which the optical fiber touch sensor according to the first embodiment of the present invention is applied.

FIG. 5 is a perspective view showing a vehicle body to which the optical fiber touch sensor according to the first embodiment of the present invention is applied.

FIG. 6 is an explanatory diagram showing a main part of the optical fiber touch sensor according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a main part of the optical fiber touch sensor according to the first embodiment of the present invention.

FIG. 8 is a graph showing a change in the amount of transmitted light of the optical fiber touch sensor according to the first embodiment of the present invention.

FIG. 9 is a perspective view, partially in section, showing a main part of an optical fiber touch sensor according to a second embodiment of the present invention.

FIG. 10 is a side sectional view showing a main part of an optical fiber touch sensor according to a second embodiment of the present invention.

FIG. 11 is an operation explanatory view of the optical fiber touch sensor according to the second embodiment of the present invention.

12A is a cross-sectional view of an optical fiber according to a conventional embodiment, and FIG. 12B is a side cross-sectional view of a touch detection unit of the optical fiber touch sensor according to the conventional embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical fiber touch sensor 10A Touch detection part 12 Optical fiber 14 Body 16 LED (Light emitting part) 18 Photodiode (Light receiving part) 26 Airbag device 30 Cover (Light absorbing means) 32 Base 34 Bridge 38 Glad part 40 Cover (Light absorbing means) 40B Bridge 42 Body panel 44 Groove

Claims (2)

[Claims] 1. An optical fiber without cladding having an atmosphere as a cladding, a light emitting portion disposed at one end of the optical fiber, a light receiving portion disposed at the other end of the optical fiber, An optical fiber touch sensor, comprising: a light absorbing means disposed on an outer peripheral portion and absorbing a part of transmission light by contacting the optical fiber. 2. The optical fiber touch sensor according to claim 1, wherein said light absorbing means is an elastic body whose inner peripheral surface is light absorbing color.