JP2005207768A - Impact detecting optical fiber sensor, and system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impact detecting optical fiber sensor system of high precision robust against an electromagnetic noise, and reduced in mechanical deterioration due to impact. <P>SOLUTION: In this impact detecting optical fiber sensor 10, an impact sensitive part 11 deflected by receiving the impact is formed by embedding a plastic optical fiber 2, and a spiral wire 7 wound preliminarily onto the plastic optical fiber 2, into a protection body 8 having prescribed hardness. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an impact detection optical fiber sensor system for sensing an impact received by a measurement object.

  In a conventional impact detection sensor, an electric sensor generally uses a pressure sensor, an acceleration sensor, and a strain gauge to detect pressure, acceleration, and strain due to impact.

  In the optical fiber type sensor, a sensor that detects the light in the optical fiber by changing the amount of light by bending loss and compression loss by applying an impact such as pressure, acceleration and strain to the optical fiber made of quartz or plastic material. is there.

  The optical fiber method is generally considered to be a loss of light due to a decrease in the bend radius of the optical fiber when the optical fiber is spirally wound around a soft cylindrical tube and the tube is deformed by the external force of the collision. There is a method of detecting collision and impact by increasing.

  The prior art document information related to the invention of this application includes the following.

Japanese Patent Laid-Open No. 9-26370 JP-A-5-249352 JP-T-2002-531812

  However, in the case of the electric shock sensor in the above-described prior art, since the shock is detected by an electric signal, the sensor itself is vulnerable to electromagnetic noise, and there is a problem that it is difficult to distinguish the signal to be detected from the noise.

  In addition, when transmitting the detection signal, there is a problem that the transmission line is susceptible to electromagnetic noise from the outside, and the influence of this noise cannot be ignored.

  There is also a problem that the electrical signal has a large transmission loss in the transmission path.

  In the case of an optical fiber type using quartz, loss occurs due to bending and compression, but due to the characteristics of the material quartz, the optical fiber causes mechanical strength deterioration due to bending and compression, and the quartz fiber does not move when an impact is applied. There is also a problem that there is a possibility of cutting.

  In the case of a plastic optical fiber, the possibility of being cut by bending or compression is low, but since the rigidity is strong, there is a problem that loss is hardly caused by bending or compression and the accuracy of the sensor is lacking.

  Accordingly, an object of the present invention is to provide a highly accurate impact detection optical fiber sensor system which is resistant to electromagnetic noise and has little mechanical deterioration due to impact.

  The present invention has been devised to achieve the above object, and the first invention is that an impact sensing member that is bent by impact is a plastic optical fiber, and a spiral wire that is wound around the plastic optical fiber in advance. Is an impact detection optical fiber sensor formed by embedding in a protective body having a predetermined hardness.

  In the second invention, the end portion of the plastic optical fiber extends longer than the impact sensing member, the end portions of the plastic optical fiber are gathered in one place, and the end portion gathered in one place The plastic optical fiber up to the impact sensing member is continuously embedded with the protective body.

  According to a third aspect of the present invention, a hollow portion without the protective body is formed in a loop inner peripheral portion of the plastic optical fiber formed by collecting the end portions of the plastic optical fiber in one place.

  According to a fourth aspect of the present invention, the plastic optical fiber has a cross-linked acrylic resin as a core material and a fluorine resin that does not transmit moisture as a cladding material.

  In a fifth aspect of the invention, the protector is ethylene propylene rubber.

  6th invention connects a light emitting element to one of the edge parts of the said plastic optical fiber extended from the impact detection optical fiber sensor of any one of the 1st-5th invention, and a light receiving element to the other of the edge part, The light from the light emitting element is input to the plastic optical fiber, the light is received by the light receiving element, and the change in the amount of received light is detected to detect the distortion of the plastic optical fiber. An impact detection optical fiber sensor system that detects the impact received by the sensing member.

  7th invention connects a light emitting element to one side of the end part of the said plastic optical fiber extended from the impact detection optical fiber sensor of any one of the 1st-5th invention, and a light receiving element to the other end part, Measurement object to which the impact detection optical fiber sensor is attached by inputting the light from the light emitting element into the plastic optical fiber, receiving the light with the light receiving element, and detecting the temporal change in the amount of the received light. The light loss pattern corresponding to the speed, weight, and stiffness of the light is determined in advance from the change in the amount of light, and the light loss pattern when shocked is compared with the previously determined light loss pattern to determine the speed, weight, and stiffness. An impact sensing optical fiber sensor system for identifying.

  According to the present invention, it is possible to obtain a highly accurate impact detection optical fiber sensor that is resistant to electromagnetic noise and has little mechanical deterioration due to impact, and a system using the same.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram showing an impact detection optical fiber sensor system 1 using an impact detection optical fiber sensor 10 according to a preferred embodiment of the present invention. FIG. 1 (a) is a front view of the impact detection optical fiber sensor system 1. FIG. 1B shows a right side view, and FIG. 1C shows a bottom view.

  In FIG. 1, an impact detection optical fiber sensor 10 is wound around a protective body 8 such as rubber or plastic, a plastic optical fiber (hereinafter referred to as an optical fiber) 2 embedded in the protective body 8, and the optical fiber 2. And a spiral metal wire (hereinafter referred to as a wire) 7.

  The impact detection optical fiber sensor 10 includes an impact sensing member 11 formed in a straight line as shown in the figure, a bent portion 8d that is provided on both sides of the impact sensing member 11, and supports the impact sensing member 11, and light from the bent portion 8d. Each part of the base 8b in which the fibers 2 are bundled at one place is formed continuously.

  The optical fiber 2 passes through one of the bent portions 8d from the base portion 8b, passes through the impact sensing member 11, passes through the other bent portion 8d, and is embedded in the protector 8 up to the base portion 8b.

  A wire 7 is wound around the optical fiber 2c for a predetermined length in advance. The optical fiber 2c is covered with the protector 8 together with the wire 7, so that the impact sensing member 11 is configured.

  The end of the optical fiber 2 extends longer than the impact sensing member 11, and the extension of the optical fiber 2 is gathered in one place by bending the extension part in a round shape, and the optical fiber 2 gathered in one place. From the end to the impact sensing member 11 is continuously embedded in the protector 8. The protector 8 also has a function of a cushion layer for removing the external force when the impact detection optical fiber sensor 10 receives an unnecessary external force.

  Since the end portions of the optical fiber 2 are gathered in one place, the optical fiber 2 forms a loop shape together with the protective body 8 covering the optical fiber 2.

  The protector 8 is formed in a flat plate shape as shown in FIG. In plan view, as shown in FIG. 1 (a), the impact sensing member 11 and the subsequent bent portion 8d are wide, and the base portion 8b is narrowed. For example, the whole is formed in an inverted flask shape. ing. A hollow portion (hereinafter referred to as a space) 8 a having no protective body 8 is formed at the inner periphery of the loop of the optical fiber 2 and the protective body 8 in the approximate center in the plan view. In the present embodiment, an oval space 8a is formed.

  The base portion 8b supports the impact sensing member 11 and the bent portion 8d, and has a shape that can be easily fixed to a frame such as an automobile. An impact sensing member 11 that is bent by receiving an impact is formed in a linear portion across the space 8a, and both ends of the impact sensing member 11 are supported by the base portion 8b via a bent portion 8d. The impact sensing member 11 may be provided, for example, in contact with the back surface of the automobile bumper.

  For example, the protective body 8 is made of ethylene propylene rubber having a predetermined hardness of about 45 to 95 degrees, and the thickness of the protective body 8 is preferably about 5 to 6 mm.

  The protector 8 may be integrally molded together with the optical fiber 2 and the wire 7 that is a spiral wire.

  Further, a protective body 8 that is divided and molded in advance is prepared, and the optical fiber 2 and the helical metal wire 7 are fitted inside the protective body 8, and the protective body is fitted with the optical fiber 2 and the helical metal wire 7. 8 may be assembled to form the impact detection optical fiber sensor 10.

  As shown in FIG. 1A, the protector 8 has a width W of about 10 to 12 mm of the impact sensing member 11 of the protector 8, and a thickness t of the impact sensing member is about 5 as shown in FIG. It is ~ 6mm. The protector 8 is formed as shown in the figure, and the optical fiber 2 is embedded in the protector 8. For this reason, the optical fiber 2 maintains the inverted flask shape as it was when embedded in the protective body 8.

  The base portion 8b is a portion in which the end portions of the optical fiber 2 guided from the respective bent portions 8d are gathered and bundled in one place and embedded in the protective body 8. The shape of the base 8b facilitates attachment workability to a measurement object such as a bumper of an automobile.

  The impact detection optical fiber sensor 10 is not limited to the shape of the protector 8 shown in FIG. In the figure, the impact sensing member 11 is formed in a substantially linear shape, and is easily bent toward the space 8a in a direction perpendicular to the longitudinal direction of the impact sensing member 11, and the impact sensing member 11 is most susceptible to an impact in this direction. The structure is easy to detect.

  For example, by providing the impact sensing member 11 in an arc shape, the impact may be detected not only from one direction but also from multiple directions orthogonal to the arc.

  The wire 7 is spirally wound around a part of the outer periphery of the optical fiber 2, so that when the impact detection optical fiber sensor 10 receives an impact, the force applied to the impact sensing member 11 due to the impact is applied to the optical fiber 2. On the other hand, it has a structure that conveys it as bending strain or compression strain. The impact sensing member 11 has a structure in which a force is applied by being concentrated on a portion where the wire 7 is in contact with the optical fiber 2 by winding the wire 7.

  The so-called microbend effect of the spirally wound wire 7 improves the optical loss sensitivity of the optical fiber 2c due to the bending strain of the optical fiber 2c generated by an external force, and makes the impact detection of the impact sensing member 11 more sensitive. Can be.

  When the optical fiber 2 is used for the wire 7, for example, the thickness of the wire 7 is preferably φ0.5 to 1.0 mm, and the winding pitch around the optical fiber 2 is preferably about 5 to 10 mm.

  An optical fiber 2f extending from the impact detection optical fiber sensor 10 extends to a control box of an automobile, and a light emitting element LD1 made of a laser diode or an LED is connected to one of the optical fibers 2f. The other end of the optical fiber 2f is connected to a light receiving element PD3 such as a photodiode for detecting light passing through the optical fiber 2c.

  For example, a heat resistant plastic optical fiber (HPOF) is used as the optical fiber 2.

  As shown in FIG. 2, the optical fiber 2 includes a core 5 portion having a high refractive index and a clad 6 portion having a low refractive index provided around the core 5, and light is transmitted through the core 5 portion. The structure is such that light does not easily leak from the clad 6 to the outside. For example, the optical fiber 2 may have a core 5 having a core diameter of 1.5 mm and a clad diameter of 2.2 mm. The core 5 is formed of a core material such as a cross-linked acrylic resin (thermosetting acrylic resin) or silicone resin, and the clad 6 is formed of a clad material such as a fluorine resin that does not transmit moisture.

  Since the optical fiber 2 is made of a fluororesin that does not transmit moisture as a clad material, it is used as a good member of the impact detection optical fiber sensor 10 that is resistant to moisture and the like.

  As shown in FIG. 1, the light emitting element LD1 is connected to a power source (not shown) via an electric signal line 4, and the light receiving element PD3 is connected to an impact detection device (not shown) via an electric signal line 4. The

  The light emitting element LD1 is an optical component such as an LD or an LED, for example, and emits light by a power source connected to the electric signal line 4 and sends the emitted light to the connected optical fiber 2.

  The light receiving element PD3 is an optical component for receiving light using, for example, a photodiode. The light receiving element PD3 converts an optical signal received from the connected impact detection optical fiber sensor 10 into an electric signal and sends it to the electric signal line 4. is there.

  Next, the operation of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the light output from the light emitting element LD1 enters the optical fiber 2, and the light is received by the light receiving element PD3. The light intensity detected by the light receiving element PD3 is transmitted as an electric signal by the electric signal line 4 to an impact detection device (not shown). In the present invention, since the impact received by the intensity change of the light passing through the optical fiber 2c is detected, the impact can be detected without being affected by electromagnetic noise in the vicinity of the impact detection optical fiber sensor 10.

  Since the light emitting element LD1 and the light receiving element are optical components that perform electro-optical conversion, it is difficult to eliminate the influence of electromagnetic noise, but the optical fiber 2f that is not affected by electromagnetic noise. By extending the light emitting element LD1 and the light receiving element PD3 at a location away from the impact detection optical fiber sensor 10, the influence of electromagnetic noise can be ignored.

  Furthermore, the light emitting element LD1, the light receiving element PD3, and the impact sensing member 11 can be provided at different positions. For this reason, electromagnetic noise can be shielded by covering light emitting element LD1 and light receiving element PD3 with a metal plate or the like.

  The impact detection optical fiber sensor 10 has the highest sensitivity for impact detection when an impact is applied by the impact sensing member 11 in a direction perpendicular to the longitudinal direction of the optical fiber 2c. This is because the impact sensing member 11 is easily supported by the bent portion 8d, so that bending strain or compression strain is likely to occur in the impact sensing member 11.

  Further, the bending strain and the compressive strain are applied to the wire 7 through the protector 8. The portion in contact with the optical fiber 2c is significantly bent by the bending strain applied to the wire 7, and the bending strain or the like is efficiently transmitted to the optical fiber 2c.

  FIG. 3 is a diagram showing a state when the impact sensing member is bent due to impact.

  The case where the impact sensing member 11 bends due to impact will be described in detail as follows.

  Due to the impact received by the impact detection optical fiber sensor 10, the impact sensing member 11 bends in the direction of the arrow 31 as shown in the figure, and a force is applied to the wire 7 and the optical fiber 2c. At this time, the force due to the bending of the protector 8 concentrates on the wire 7 wound around the optical fiber 2c, and the force concentrated on the wire 7 causes the optical fiber 2c to bend locally by the wire 7 bending the optical fiber 2. Added to.

  By providing the space 8a, the protector 8 is easily bent when receiving an impact, and the impact detection sensitivity of the impact sensing member 11 is improved.

  For this reason, a remarkable bending strain is generated in the optical fiber 2c by the wire 7, and the transmission loss of the optical fiber 2c increases due to this bending strain. Due to this increase in bending strain, the amount of light passing through the optical fiber 2c decreases.

  When the light receiving element PD3 receives this light amount via the optical fiber 2f, the increase or decrease of the received light amount can be known. This temporal change in the amount of light appears as shown in FIG.

  FIG. 5 is a diagram showing a change with time of the amount of light passing through the optical fiber 2 c of the impact detection optical fiber sensor 10. In the figure, the horizontal axis indicates time, and the vertical axis indicates the amount of light received by the light receiving element PD3.

  At time t1 in the figure, an impact is applied to the impact detection optical fiber sensor 10, and the impact sensing member 11 of the impact detection optical fiber sensor 10 is bent. The impact reaches the maximum at time t2, and at this time, the optical fiber 2c has the maximum bending strain and the transmission loss of the optical fiber 2c becomes the maximum.

  As the impact applied to the impact detection optical fiber sensor 10 is relaxed, the deflection of the impact sensing member 11 is reduced, the bending strain of the optical fiber 2c is also relaxed, and the transmission loss of the optical fiber 2c is reduced.

  When the impact disappears at time t3, the impact sensing member 11 is not bent and returns to the shape of the impact sensing member 11 before the impact is applied. At this time, the bending strain caused by the optical fiber 2c returning to the state before the impact application is eliminated, and the transmission loss of the optical fiber 2c also returns to the state before the impact application.

  Thus, by inputting light to the optical fiber 2c and detecting the change in the amount of light received by the light receiving element PD3, the strain of the optical fiber 2c is detected, and the impact received by the impact sensing member 11 from the strain is detected. Can be detected.

  Here, the speed, weight, stiffness, and the like at the time of different impacts applied to the measurement object can be identified from the state of change in light quantity (light loss pattern) at times t1 to t3.

  For example, even when an impact of the same magnitude is applied to an automobile, the change in the amount of light detected by the impact detection optical fiber sensor 10 mounted on the automobile is the slope of the change in the amount of light in the figure depending on the traveling speed of the automobile. The size is different or the time t2 until reaching the peak is different. That is, the change in the amount of light obtained becomes a unique light loss pattern corresponding to the speed.

  Even when an impact of the same magnitude is applied to an automobile, in the case where the mass of the automobile is different, the change in the amount of light detected by the impact detection optical fiber sensor 10 is caused by the inclination or magnitude of the change in the amount of light in the figure depending on the mass of the automobile. Or the time t2 until reaching the peak is different. That is, the change in the amount of light obtained becomes a unique light loss pattern corresponding to the mass of the automobile.

  In addition, even when the same impact is applied to the car, if the bumper or the body of the car is different, the change in the amount of light obtained will be a unique pattern corresponding to the firmness of the car body, etc. .

  In this way, by inputting light into the optical fiber 2c and detecting a temporal change in the amount of light received by the light receiving element PD3, the speed, weight, and rigidity of the measurement object attached with the impact detection optical fiber sensor 10 are detected. A light loss pattern corresponding to the thickness can be obtained in advance from a change in the amount of light, and the speed, weight, and stiffness can be identified by comparing the light loss pattern upon impact with the light loss pattern obtained in advance.

  When the impact sensing member 11 is compressed by an impact, the situation is substantially the same as described above.

  FIG. 4 is a diagram illustrating a state when the impact sensing member is impacted and compressed.

  As shown in FIG. 4, the impact sensing member 11 is compressed in the direction of the arrow 31 by the impact received by the impact detection optical fiber sensor 10, and the force is applied to the wire 7 and the optical fiber 2c through the compression of the protector 8. Join. A force due to compression of the protector 8 is concentrated on the wire 7 wound around the optical fiber 2c, and this force is applied to the optical fiber 2c.

  For this reason, remarkable compressive strain is generated in the optical fiber 2c by the wire 7, and the transmission loss of the optical fiber 2c increases due to this compressive strain. The amount of light passing through the optical fiber 2c decreases due to the increase in compression strain. When this light quantity change is received by the light receiving element PD3 through the connected optical fiber 2f, this temporal change in the quantity of light appears in the same manner as the temporal change pattern shown in FIG.

  By using the present invention, it is possible to eliminate the influence of electromagnetic noise and transmission loss, which were problems with conventional electric shock sensors.

  In addition, compared to an impact detection sensor using a silica glass optical fiber, the impact detection optical fiber sensor 10 according to the embodiment in which a spiral wire is mounted is less likely to cause fatigue cutting of the silica glass optical fiber due to bending and compression. A highly reliable sensor system can be configured.

  Compared to a conventional impact detection sensor using an optical fiber, the impact detection optical fiber sensor 10 efficiently causes bending or compression of the optical fiber due to the impact. Therefore, the impact detection optical fiber sensor 10 is a high-sensitivity sensor that can accurately detect an applied impact.

  An optical fiber 2 having a cross-linked acrylic resin as a core material and a fluorine resin that does not transmit moisture as a cladding material is used as a good member of the impact detection optical fiber sensor 10 that is not affected by electromagnetic noise and is resistant to moisture and the like. be able to.

  The protector 8 retains the shape of the optical fiber 2 embedded in the protector 8, and bends when the impact sensing member 11 receives an impact due to the loop shape (reverse flask shape). It effectively transmits the bending stress caused by the impact to the surface. The protector 8 also has a function of a cushion layer that removes unnecessary external force, and the base 8b of the protector 8 has a shape that can be easily attached to the measurement object.

FIG. 1A is a front view of an impact detection optical fiber sensor system. FIG. 1B is a right side view of the impact detection optical fiber sensor system. FIG. 1C is a bottom view of the impact detection optical fiber sensor system. It is sectional drawing which shows the cross section of a plastic optical fiber. It is a state figure which shows a state when an impact sensing member receives an impact and bends. It is a state figure which shows a state when an impact sensing member receives an impact and is compressed. It is a time change figure which shows the change of the light quantity which passes an impact detection optical fiber sensor.

Explanation of symbols

1 Shock detection optical fiber sensor system 2 Optical fiber (plastic optical fiber)
2c Optical fiber (plastic optical fiber)
2f Optical fiber (plastic optical fiber)
4 Electrical signal line 7 Spiral metal wire (wire)
8 Protective body 8a Space 8b Base 8d Bend 10 Impact detection optical fiber sensor 11 Impact sensing member LD1 Light emitting element PD3 Light receiving element t Thickness W Width

Claims (7)

  The impact sensing member that is bent upon impact is formed by embedding a plastic optical fiber and a spiral wire wound around the plastic optical fiber in a protective body having a predetermined hardness. Detection optical fiber sensor.   The end portion of the plastic optical fiber extends longer than the impact sensing member, the end portions of the plastic optical fiber are gathered in one place, and the plastic from the gathered end portion to the impact sensing member The impact detection optical fiber sensor according to claim 1, wherein the optical fiber is continuously embedded with the protective body.   The impact detection light according to claim 1 or 2, wherein a hollow portion without the protective body is formed in an inner peripheral portion of the loop of the plastic optical fiber formed by collecting end portions of the plastic optical fiber at one place. Fiber sensor.   The impact detection optical fiber sensor according to any one of claims 1 to 3, wherein the plastic optical fiber includes a cross-linked acrylic resin as a core material and a fluorine resin that does not transmit moisture as a cladding material.   The impact detection optical fiber sensor according to any one of claims 1 to 4, wherein the protective body is ethylene propylene rubber.   A light emitting element is connected to one end of the plastic optical fiber extended from the impact detection optical fiber sensor according to any one of claims 1 to 5, and a light receiving element is connected to the other end of the plastic optical fiber. Is input to the plastic optical fiber, the light is received by a light receiving element, and a change in the amount of received light is detected to detect distortion of the plastic optical fiber, and the impact sensing member receives the distortion from the distortion. An impact detection optical fiber sensor system for detecting the impact. A light emitting element is connected to one end of the plastic optical fiber extended from the impact detection optical fiber sensor according to any one of claims 1 to 5, and a light receiving element is connected to the other end of the plastic optical fiber. Is input to the plastic optical fiber, the light is received by the light receiving element, and the temporal change in the amount of the received light is detected, so that the speed, weight, A light loss pattern corresponding to the stiffness is obtained in advance from the change in the amount of light, and the speed, weight, and stiffness are identified by comparing the light loss pattern upon impact with the previously obtained light loss pattern. Shock detection optical fiber sensor system.

Images