JPH07151563A - Optical fiber energy feeding sensor - Google Patents

Abstract

PURPOSE:To eliminate an electromagnetic hazard, by converting the light received from the end of an optical fiber into electric power, detecting the external data by a sensor by using the above electric power and converting into an electric signal, and furthermore, converting the electric signal into an optical signal. CONSTITUTION:An optical fiber 20 is used to connect between a sensor 10 and a control circuit 30, and the light received to a light receiver 17 from the end of the fiber 20 is converted into an electric power by a light-power converter 11. A sensor 13 detects the external data by using the above electric power, the output electric signal of the sensor 13 is converted into an optical signal by a power-light converter 15, and the light is input to the end of the fiber 20. Consequently, the circuit 30 and the censor 10 can be connected by a single line of the fiber 20, so as to realize a light weight. Furthermore, since there is no electric line between the circuit 30 and the sensor 10, the possibility to receive an electromagnetic noise is also reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for detecting external information and can be used in various fields such as automobiles, railroads and ships.

[0002]

2. Description of the Related Art Conventionally, a sensor converts various kinds of energy such as mechanical energy, thermal energy and magnetic energy into electric energy by using a variable resistor, a strain gauge, an electric contact, a thermoelectric conversion element, a magnetoresistive element and the like. It was configured to send to the control circuit via an electric wire. 61-21
Japanese Patent No. 967 discloses an example of a rotation sensor using a magnetoresistive element.

FIG. 6 shows an example of a vehicle-mounted speed sensor. The sensor chip section 6 and the control circuit 8 are connected by an electric wire 7. In the sensor chip portion 6, the magnet ring 61 is magnetized along the outer circumference and rotates in conjunction with the axle of the vehicle. The magnetic resistance element 62 is arranged in the vicinity of the magnet ring 61, and the sensor IC 63 fixed to the vehicle detects a change in the resistance value of the magnetic resistance element 62,
An electric signal is emitted to the electric wire 7. On the other hand, the control circuit 8 receives an electric signal from the electric wire 7 and performs various controls. Here, the power supply of the sensor IC 63 is received from the control circuit 8 via the electric wire 7.

The magnetic resistance element 62 is a magnet ring 61.
When is rotated, its internal resistance changes. Sensor IC6
3 receives the electric power from the control circuit 8, and the magnetoresistive element 62
Since the resistance change of is converted into an electric signal, the control circuit 8 can obtain the rotation speed of the axle of the vehicle from the state of the electric signal.

The electric wire 7 requires three electric wires of two power lines of + and- (or ground) and a signal line. In a vehicle, the electric wire can be omitted by connecting the sensor chip 6 and the control circuit 8 to the body of each place by using the body ground, so at least two electric wires 7 are required. Becomes However, since the important signal line does not generate a potential difference, three electric wires are required.

On the other hand, recently, a technique for transmitting and receiving an optical signal through an optical fiber has been developed. here,
The signal lines are replaced with optical fibers, and signals are transmitted and received by light.

[0007]

The electric wire is heavy because it uses a copper wire inside. Two to three heavy wires are required for one sensor. For example, as shown in FIG. 7, in a vehicle, wheel speed sensors 91 to 94 that detect the wheel speeds of four wheels are arranged near each wheel. On the other hand, the control circuit 95 is fixed to one place of the vehicle. The distance between the control circuit 95 and each wheel speed sensor 91-94 is 1.5 meters or more. If there are three electric wires between the control circuit 95 and the wheel speed sensors 91 to 94, the total length of the electric wires is 18 meters or more. The weight of the electric wire is about 4.8 g / m, though it depends on the thickness of the electric wire.
Therefore, the electric wire for the wheel speed sensor alone weighs 86.4 g. In the vehicle, dozens of other sensors are used in addition to these, and the total weight of the electric wires connecting the control circuit and the sensor of the entire vehicle is considerable.

Further, if an electric wire is used, the electric wire itself serves as an antenna, which may cause electromagnetic interference. Therefore, it is necessary to remove electromagnetic noise on the control circuit side.

Here, replacing the signal line connecting the sensor and the control circuit with an optical fiber has a considerable effect on electromagnetic interference, but the power line is still necessary,
Although the optical fiber is slightly lighter in weight, it is not as effective as expected because an optical-electrical converter and an electric-optical converter are required for both the sensor and the control circuit.

Therefore, it is an object of the present invention to eliminate the electromagnetic interference and to reduce the weight of the connecting wire between the sensor and the control circuit.

[0011]

In order to solve the above-mentioned problems, in the invention of claim 1, a light-receiving portion for connecting a sensor and a control circuit with an optical fiber and receiving light from an end portion of the optical fiber, A light-power converter that converts the light received by the light-receiving unit into electric power, a sensor unit that detects external information using the electric power generated by the light-power converter and converts it into an electric signal, and an electric signal of the sensor unit To an optical signal, and an electro-optical converter that emits light toward the end of the optical fiber constitutes an optical fiber energy supply sensor.

In the invention of claim 2, in claim 1, the electro-optical converter emits an optical signal having a wavelength different from the wavelength of the light received from the optical fiber.

[0013]

According to the invention of claim 1, when light is supplied to the optical fiber, the light is guided to the light receiving portion. The light guided to the light receiving section causes the light-power converter to generate electric power, and the electric power causes the sensor section to operate. The sensor unit detects external information and emits an electric signal.

This electric signal is converted into an optical signal by the electro-optical converter, and emits light toward the end of the optical fiber. Therefore, when the control circuit side supplies light to the optical fiber, external information can be obtained from the same optical fiber by an optical signal. At this time, there is only one optical fiber between the sensor and the control circuit, and the sensor does not require any other power line.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, an embodiment of the present invention includes a fiber-optic energy supply sensor 10 for a light-power converter 1.
1, power supply circuit 12, sensor unit 13, and sensor element 1
4 and an electro-optical converter 15 having a light emitting diode 16
Equipped with. An optical fiber 20 is attached to the optical fiber energy supply sensor 10 by an attachment portion 21.
The tip of the optical fiber 20 is directed to the light receiving unit 17. The light-power converter 11 uses, for example, a solar cell,
It is arranged so as to face the light receiving unit 17. The power supply circuit 12 adjusts the power output from the light-power converter 11 so as to be suitable for supplying to the sensor unit 13. The sensor unit 13 receives electric power from the power supply circuit 12, detects a change in the sensor element 14, and outputs a pulse signal from the output terminal, which alternately switches the high level voltage and the low level voltage. The duty ratio of the pulse signal is changed according to the state of the sensor element 14. The pulse signal is sent to the electro-optical converter 15. The electro-optical converter 15 causes the light emitting diode 16 to blink according to the pulse signal. The light emitting diode 16 has directivity,
As shown in FIG. 3, it faces the tip of the optical fiber 20. In this embodiment, the light emitting diode 16 is a visible light emitting diode with a lens and emits visible light (center wavelength of about 0.63 to 0.64 microns) toward the optical fiber 20.

The other end of the optical fiber 20 is connected to the control circuit 30. The control circuit 30 operates by receiving power from the battery 40. The control circuit 30 includes a power supply circuit 31, a microcomputer 32, and an optical input / output device 33. The power supply circuit 31 converts the voltage of the battery 40 into the rated voltage of the microcomputer 32. The microcomputer 32 receives the voltage from the power supply circuit 31 and receives the optical input / output device 33.
And receives a signal from the optical input / output device 33. As shown in FIG. 2, the optical input / output unit 33 includes a lens 35, a pedestal 36, and a lens 35 in a housing 34 having one end opened.
A light emitting diode 37 and a photodiode 38 provided on the pedestal 36 are provided. The open end of the housing 34 faces the other end of the optical fiber 20. The light emitting diode 37 receives a signal from the microcomputer 32,
It emits light. The internal resistance of the photodiode 38 changes according to the amount of light received, and the change is detected by the micro-computer 32. The light emitting diode 37 is arranged to emit light to the optical fiber 20 via a lens.
The photodiode 38 is arranged to receive the light from the optical fiber 20 through the lens. In this embodiment, the light emitting diode 37 is an infrared light emitting diode having a center wavelength of about 0.85 μm.

The power supply circuit 12 of the above-described optical fiber energy supply sensor 10 is composed of a capacitor C1 connected to both ends of the light-power converter 11, as shown in FIG. Further, the electro-optical converter 15 includes a transistor Tr.
1, a resistor R1. Light emitting diode 16, resistance R1
The transistor Tr1 is connected in series between both ends of the light-power converter 11. The transistor Tr1 opens and closes according to a signal from the sensor unit 13. As described above, the sensor unit 13 detects the change in the sensor element 14 and outputs the pulse signal at which the high level voltage and the low level voltage are alternately switched from the output terminal.
Blinks in response to the pulse signal.

In the above example, when the microcomputer 32 of the control circuit 30 sends an electric signal to the optical input / output device 33, the light emitting diode 37 of the optical input / output device 33 emits light, and the optical fiber energy supply sensor via the optical fiber 20. The light-power converter 11 of 10 is irradiated with infrared light. As a result, the light-power converter 11 generates electric power and stores the electric power in the capacitor C1 of the power supply circuit 12. This electric power is given to the sensor unit 13, and the sensor unit 13 outputs the sensor element 14
Change is detected, and a pulse signal corresponding to this change is output. The electro-optical converter 15 receiving this pulse signal causes the light emitting diode 16 to blink in response to the pulse signal. When the light emitting diode 16 emits light, this light is sent to the optical input / output device 33 of the control circuit 30 via the optical fiber 20. In the light input / output device 33, this light is applied to the photodiode 38 by the lens 35. The internal resistance of the photodiode 38 changes according to the amount of received light, and the micro computer 32 detects this change. Therefore, the microcomputer 32 can determine whether or not the light emitting diode 16 is emitting light. The microcomputer 32 can see the change of the sensor element 14 by looking at the light emission period, the on / off time and the duty ratio, and can control another device according to the detected value of the sensor element 14.

Here, in the optical fiber 20, the light from the light emitting diode 37 of the optical input / output device 33 and the light from the light emitting diode 16 of the optical fiber energy supply sensor 10 are simultaneously transmitted and received.
Since 7 emits infrared light and the light emitting diode 16 of the optical fiber energy supply sensor 10 emits visible light, there is no interference.

When the light emitted from the light emitting diode 37 is infrared light, power can be generated particularly efficiently when a solar cell is used as the light-power converter 11.

As another means for avoiding interference,
The light emission of the light emitting diode 37 may be stopped during the light emission of the light emitting diode 16. However, in this case, the power generated by the light-power converter 11 is reduced, so that the power consumption of the sensor unit 13 is limited to a small case.

In the above embodiment, only the optical fiber 20 connected to the control circuit 30 is connected to the optical fiber energy supply sensor 10. Usually, the weight per unit of electric wire is 4.8 g / m and the weight per unit of optical fiber is 3.8 g / m. In order to connect the control circuit and the sensor with electric wires, usually three electric wires are required.
[(4.8 × 3) −3.8] / (4.8 × 3) × 100
This means that the weight has been reduced by 73.6%.

Although the capacitor C1 is used as the power supply circuit 12 of the optical fiber energy supply sensor 10 in the above embodiment, a rechargeable storage battery may be used instead of the capacitor C1.

When the power consumption of the sensor unit 13 is large, the sensor unit 13 may be operated only when necessary. In order to send a signal to the sensor unit 13, as shown in FIG. 5, a resistor R2 is arranged between the capacitor C1 and the light-power converter 11, and the light-power converter 11 is connected to the capacitor C2.
It is advisable to connect to the input terminal of the sensor unit 13 via. According to this, the capacitor C1 is charged via the resistor R2. Further, when the light applied to the light-power converter 11 is temporarily cut off, the capacitor C2 transmits only the change to the sensor unit 13. A change in the input terminal is used as a trigger to switch between stopping and performing the operation of the sensor unit 13. According to this, the microcomputer 3
When the output of 2 is cut off momentarily, a signal is input to the input terminal of the sensor unit 13 and the operation of the sensor unit is stopped. After that, the light-power converter 11 continues to receive light and continues to charge the capacitor C1. When the output from the microcomputer 32 is momentarily cut off again when information from the sensor unit 13 is needed, a signal is input to the input terminal of the sensor unit 13 and the sensor unit starts to operate.
The microcomputer 32 can obtain the sensor signal. As described above, according to the configuration of FIG. 5, the capacitor C1 is always charged, and the sensor unit 13 receives power only when necessary, and operates, so that the light-power converter 11 is constantly generated. The optical fiber energy supply sensor 10 can be operated even if the power consumption of the sensor unit 13 is larger than the electric power.

As described above, in this embodiment, the optical fiber 2 is provided between the sensor 10 and the control circuit 30.
It is generated by the light receiving unit 17 connected with 0 and receiving light from the end of the optical fiber 20, the light-power converter 11 converting the light received by the light receiving unit 17 into electric power, and the light-power converter 11. A sensor unit 13 that detects external information using electric power and converts it into an electric signal; and an electro-optical converter 15 that converts the electric signal of the sensor unit 13 into an optical signal and emits light toward the end of the optical fiber 20. An optical fiber energy supply sensor 10 was constructed from the above.

Therefore, since the control circuit 30 and the sensor 10 can be connected with one of the optical fibers 20, the weight can be significantly reduced as compared with the case of connecting with three electric wires. Further, since there is no electric wire between the control circuit 30 and the sensor 10, the possibility of receiving electromagnetic noise is reduced, and it becomes stronger against electromagnetic interference.

Further, in the present embodiment, the electro-optical converter 15 is adapted to emit an optical signal having a wavelength (visible light) different from the wavelength of light received from the optical fiber 20 (infrared light).

Therefore, the light for power supply and the light for signal transmission do not interfere in the optical fiber 20, and the power and signal can be transmitted at the same time. Therefore, the power generated by the light-power converter 11 is large, which is efficient.

[0029]

According to the invention of claim 1, since the control circuit and the sensor can be connected with one optical fiber, the weight can be reduced. Further, since there is no electric wire in the control circuit and the sensor, it is strong against electromagnetic interference.

According to the second aspect of the invention, the light for power supply and the light for signal transmission do not interfere in the optical fiber, and the power and signal can be transmitted at the same time. Therefore,
The light-power converter generates a large amount of power, which is efficient.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of an optical fiber energy supply sensor and control circuit of the present invention.

FIG. 2 is a sectional view of an optical input / output device of a control circuit.

FIG. 3 is a perspective view of a light-to-power converter of an optical fiber energy supply sensor.

FIG. 4 is a circuit diagram of an embodiment of an optical fiber energy supply sensor of the present invention.

FIG. 5 is a circuit diagram of another embodiment of the optical fiber energy supply sensor of the present invention.

FIG. 6 is a circuit diagram of a conventional sensor.

FIG. 7 is a circuit wiring diagram of a wheel speed sensor in a vehicle.

[Explanation of symbols]

 10 Optical Fiber Energy Supply Sensor 11 Light-Power Converter 12 Power Supply Circuit 13 Sensor Section 14 Sensor Element 15 Electric-Optical Converter 16 Light Emitting Diode 20 Optical Fiber 21 Mounting Section 17 Light-Receiving Section 30 Control Circuit 40 Battery 31 Power Supply Circuit 32 Microcomputer 33 Optical Input / output device 34 Housing 35 Lens 36 Base 37 Light emitting diode 38 Photodiode C1, C2 Capacitor Tr1 Transistor R1, R2 Resistance 91-94 Wheel speed sensor 95 Control circuit

Claims (2)

[Claims] 1. A light receiving unit for receiving light from an end of an optical fiber, a light-power converter for converting light received by the light receiving unit into electric power, and electric power generated by the light-power converter. Optical fiber including a sensor unit for detecting external information by converting the electric signal into an electric signal, and an electro-optical converter for converting the electric signal of the sensor unit into an optical signal and emitting light toward the end of the optical fiber. Energy supply sensor. 2. The optical fiber energy supply sensor according to claim 1, wherein the electro-optical converter emits an optical signal having a wavelength different from a wavelength of light received from the optical fiber.