JPS6036921A - Optical load detector - Google Patents

Abstract

PURPOSE:To improve resistance to noise and provide an excellent insulating characteristic and separability from other system by detecting load with light as a medium by making use of the characteristic of an optical fiber which increases a light transmission loss with a side pressure. CONSTITUTION:Light Lis is made incident into an optical fiber 1a on a load detection side from a light transmitter 2. The light Lo generating a light transmission loss by passing through a load detecting part 5 is transmitted to a light receiver 3a on the load detection side. The same light Lis as 1a is made incident into an optical fiber 1b on a reference light side from the transmitter 2 and the reference light Li generating no loss with load is transmitted to a light receiver 3b on the reference light side having the same characteristic as the receiver 3a. An arithmetic circuit 4 receives the signals Lo', Li' amplified and converted by the receivers 3a, 3b and calculates the load from the light transmission loss by operating log (Lo'/Li'). The part 5 transmits the load to a body 7 for applying a nonuniform side pressure upon receiving load W and applies the nonuniform side pressure to the fiber 1a.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a load detector that detects force applied to an object, and has particularly excellent noise resistance against strong electric currents and magnetic fields, and environmental resistance against temperature, humidity, etc. , relates to a load detector compatible with a sensor of an optical information transfer processing system.

[Background of the invention]

In order to do this, a method is used to convert the applied force into a mechanical deformation amount using a spring or the like and then detect it.

In order to convert this amount of deformation into a load, there are two methods: directly reading the amount of deformation, and converting it into an electrical quantity and displaying it.

Furthermore, when the amount of deformation due to a load is small, a method is generally used in which the strain produced in the object subjected to the force is converted into an electrical quantity by using a resistance change using a strain gauge or a magnetostrictive phenomenon.

The output value of such a strong method is about several iomv at most. Therefore, it is extremely disadvantageous to install it in a place where electromagnetic noise may occur or in a place with high humidity.

[Purpose of the invention]

An object of the present invention is to provide an optical load detector that has excellent noise resistance and insulation properties and is suitable as a sensor for an optical information transmission processing system.

[Summary of the invention]

has lateral pressure characteristics. This is a characteristic that when nonuniform lateral pressure acts on an optical fiber, microbending occurs and light transmission loss increases. For example, Figure 1 shows an example of measuring the load and increase in optical transmission loss when two sheets of sandpaper are used to apply uneven lateral pressure, and an optical fiber is inserted between them and a load is applied. . In other words, if the load is W and the optical transmission loss caused by the load W is ξ, ξ is expressed as a function of W. (ξ) (Kg) (2) That is, the load W can be known from the optical transmission loss increase ξ.

Although Fig. 1 shows a general example in which the load W and loss increase ξ are non-linear, it is possible to obtain an optical fiber in which W and ξ are linear by changing the way the coating layer is attached to the optical fiber core. . In the case of such an optical fiber, (1), (2)
The relationship between the equations is ξ=α·W (dB) (1)' W=1·ξ (Kg) (2)' α.

On the other hand, as shown in Fig. 2, one optical fiber is connected to 1.
2...n, and load wl, W in each section
2... By applying non-uniform side pressure by Wl, the loss increase in each section becomes ξ1 ξ2...ξn, the light intensity of the optical fiber input light 11+s output light at the boundary of the LO section becomes Ll, L2, respectively. ...If Lll-1, then the relationship holds true.If you take the logarithm of both sides and multiply it by 20, each term on the right side is equal to ξ1.ξ3...ξn.In other words, from the relationship of equation (1) 7, This shows that by measuring and calculating the emitted light, it is possible to determine the sum of the loads applied to the optical fiber in multiple sections. , which shows the possibility of measuring the total force exerted on the object with a single optical fiber.

In addition, as the detection principle uses the optical transmission loss increasing characteristic of optical fibers, the detector itself is not affected by electromagnetic fields.Since the detection amount is transmitted by light, the transmission path is also not affected by electromagnetic fields. Do not receive.

In addition, unlike the case of strain gauges, there is no need in principle to provide a connection between the detection section and the transmission line diagram.

Since the optical fiber itself has high resistance to environments such as temperature and humidity, it is possible to eliminate the drawbacks of the current technology. [Embodiments of the Invention] Examples of the present invention will be explained below with reference to the drawings. do.

FIG. 3 is an example of an optical load detector. 1a is the light LLs input from the optical transmitter 2, and the light Lo that has passed through the load detection unit 5 and generated optical transmission loss is sent to the load detection side optical receiver 3.
1b is the optical transmitter 2.
A reference light side optical fiber (same specifications as la) that receives the same light Lis as 18 and transmits the reference light Li to the reference light side optical receiver 3b having the same characteristics as 3a without causing loss due to load; 4 is amplified/converted L by receivers 3a, 3b
tOg(
This is a calculation circuit that performs the calculation of T7) and calculates the load from the optical transmission loss. As shown in FIG. 4, the load detection unit 5 is a load receiver that receives a load W and transmits the load to the non-uniform side pressure applying body 7, and a load detection optical fiber 7 that receives the load W. Apply uneven lateral pressure to 1a. 8 is a case that accommodates these.

In this embodiment, the reference light side optical fiber 1b and the reference light side optical receiver 3b are used, but when strict correction is not required or when no load is applied to the load detection section 5, the 38-injection If the light LO is stored in the arithmetic circuit 4 as the reference light Ll, and a circuit is added to 4 to perform the necessary calculations between the 38 incident lights Lo after applying a load to the load detection section, the result shown in FIG. The reference light side optical fiber 1b and the reference light side optical receiver can be omitted.

In the embodiment shown in FIG. 3, there is one load detection section 5, but the fifth
As shown in the figure, it is also possible to calculate the load sum by sequentially passing the load detection side optical fiber through a plurality of load detection units 5a, 5b, . . . 5n.
Other embodiments of the invention are possible.

Further, if the load receiver 6 is replaced with a diaphragm or the like that is displaced by the process pressure as shown in FIG. 4, it is possible to measure the process pressure and liquid level, and these are also examples of the present invention.

〔Effect of the invention〕

According to the present invention, the load can be detected using light as a medium by utilizing the lateral pressure-light transmission loss increase characteristic of the optical fiber. Load detection with extremely high accuracy is possible.

(2) Since optical fiber is used, insulation and isolation from other systems are excellent.

(3) Since the optical fiber itself has high resistance to high temperature and high humidity, it has excellent environmental resistance.

(4) By using the load detection units in series, there is great potential for applied measurements such as being able to determine the total load.

(5) Compatible with optical information processing systems.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram of the uneven lateral pressure load of an optical fiber and increase in optical transmission loss, Figure 2 is an explanatory diagram of various quantities when multiple loads are applied to one optical fiber, and Figure 3 is a diagram of the characteristics of the optical fiber of the present invention. Detailed explanatory drawings, Figure 4 is a structural diagram of the load detection section in Figure 3, Figure 5 is the structural diagram of the load detection section in Figure 3.
FIG. 3 is an explanatory diagram of an application example in which a plurality of load detection units are provided in the figure. 1a...Load detection optical fiber, 1b...Reference light optical fiber, 2...Optical transmitter, 3a...Load detection side optical receiver, 3b...Reference light side optical receiver, 4 ...Arithmetic circuit, 5...Load detection unit, 6...Load receiver, 7...Ununiform lateral pressure application salary. ]

Claims (1)

[Claims] 1. In an optical transmitting/receiving device consisting of an optical transmitter, an optical receiver, and an optical fiber that optically couples the two, it is known in advance that the optical transmission loss will increase when the optical fiber is subjected to uneven lateral pressure. An optical load detector is characterized in that the load is read by a circuit that uses a fiber to apply uneven lateral pressure to the optical fiber, measures the increase in loss that occurs in the optical fiber, and converts it into a load.