JPS6329221A - Optical temperature sensor - Google Patents

Abstract

PURPOSE:To reduce the passage loss of light and to enable assembly without any adjustment by controlling the movement of a movable member which supports the tip parts of two optical fibers arranged in the same groove so as to have their end surfaces opposite each other by shape memory alloy, and controlling the operation of the shape memory alloy by an inversion plate. CONSTITUTION:The two optical fibers 8a and 8b are arranged in the V groove 9 so as to have their end surfaces opposite and their optical axes are aligned with each other. The tip of the optical fiber 8a is supported by the movable member 10 through a leaf spring 13 and a coil spring 11. The movable member 10 is supported by the coil-shaped shape memory alloy 12. When the ambient temperature rises above constant temperature, the movable member 10 is pushed up with the restoring force of the shape memory alloy 12. Consequently, an end of the inversion plate 14 contacts a projection 15a and when force larger than a constant value is applied, the inversion plate 14 is turned over and deforms from a shape shown by a dotted line to a shape shown by a solid line to push up the movable member 10. The tip of the optical fiber 8a is pushed up to cut off the transmission of light between the optical fibers 8a and 8b, so that this device functions as an optical temperature sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a temperature sensor using an optical fiber for detecting heating temperature.

BACKGROUND OF THE INVENTION Conventionally, this type of optical temperature sensor has had a configuration as shown in FIG. In FIG. 3, 1a.

1b is an optical fiber, 2a and 2b are rod lenses, 3 is the original shielding plate, 4 is a coil-shaped shape memory alloy, and 5 is a spring. In the figure, light emitted from an optical fiber 1a is converted into parallel light rays 6 by a rod lens 2a, and a shielding plate 3
After passing through the hole 7 provided in the rod lens 2b,
The light is again focused and enters the optical fiber 1b. When the outside temperature rises, the shape memory alloy 4 shrinks, for example, so the shielding plate 3 blocks the parallel light rays 6, and no light enters the optical fiber 1b. When the outside temperature falls, the shrinking force of the shape memory alloy 4 disappears, the spring 6 contracts and the shielding plate 3 returns to its original position, so the parallel light ray 6 passes through the hole again and enters the original fiber 1b. .

The problem that the invention aims to solve In such a conventional configuration, the mouth and drain lens 21L.

Since two 2b's are used, the transmission loss of light is large, the number of twisted parts is large, and complicated optical axis adjustment is required during assembly. In addition, shape memory alloys move slowly in response to temperature changes, and there is a problem in that light cannot be blocked quickly. The present invention is intended to solve these problems, and aims to provide a device with low light transmission loss, without the use of lenses, and with almost no adjustment required.

To solve this problem, the present invention aligns the optical axes of two optical fibers with their end faces facing each other using a groove, and the tip of at least one original fiber. A movable member that moves the part outward of the groove is operated using a shape memory alloy, and the
The motion of the shape memory alloy is controlled using an inversion plate that rapidly deforms or restores itself when a force is applied.

Function: With this configuration, there are fewer components because no opening or lens is used, and no optical axis adjustment is required because a groove is used. Furthermore, temperature can be detected with a simple configuration in which the original fiber is moved using a shape memory alloy that changes shape due to temperature and an inversion plate that rapidly deforms or restores itself when a force above a certain value is applied, and can be used as an optical temperature sensor. Functional 1° Embodiment FIG. 1 is a block diagram of an optical temperature sensor according to an embodiment of the present invention. In FIG. 1, sa and sb are optical fibers,
9 is a V groove, 1o is a movable member, 11 is a coil spring, 12 is a coil-shaped shape memory alloy, 13 is a leaf spring, 14 is an inversion plate fixed with the position of the movable member 1o as a fulcrum, and 16 is one side of the inversion plate 14 It is a protrusion that hooks the end of the

FIG. 2 is an explanatory diagram of the main parts of this embodiment. The configuration and operation will be explained below using FIG. 2. The optical fiber 8b is fixed in the V-groove 9. The optical fiber 8a has its tip facing the optical fiber 8b with an interval of about 30 μm, and
It is pressed into groove 9. In this way, the V-groove 9 is used to form the optical fiber 8a.

By abutting 8b, the optical axes of the optical fibers can be mechanically aligned.

Reference numeral 14 in the same figure is, for example, a metal reversal plate, which deforms rapidly when a force of more than a certain value is applied in a certain direction, and the force disappears.
It has the property of rapidly restoring itself when a certain amount of force is applied in the opposite direction. Note that the coil-shaped shape memory alloy 12 in the figure has a property of returning to its original shape after being deformed when the temperature exceeds a certain level.

At room temperature, the temperature of the shape memory alloy 12 is also at room temperature, and since the coil spring 11 has a stronger compressive force than the shape memory alloy 12, the movable member 10 receives a downward force in the figure. At this time, the reversing plate 14 also tries to move downward following the movable member 10, but one end hits the position of the protrusion 15b and cannot be moved. However, when a force exceeding a certain value is applied, the shape memory alloy 12 deforms and comes off the protrusion isb, moving the movable member 1o downward, so that the shape memory alloy 12 receives the pressure and becomes deformed. In this state, the original fiber &

8b, the optical axes are aligned in the V groove 9, and the light is transmitted to the original fiber 8.
is transmitted from a to 8b.

Returning to FIG. 1 again, the explanation will be continued. When the ambient temperature rises to a certain level or higher, the coil-shaped shape memory alloy 12 generates a force that returns to its original shape and pushes the movable member 10 upward, causing the end of the reversing plate 14 to collide with the protrusion 15''a. When a force exceeding a certain value is applied, the reversing plate 14 is rapidly deformed (restored) and detached from the projection 15ia, pushing the movable member 1o upward and compressing the coil spring 11. When the movable member 1° is pushed up, , as shown in the figure, the movable member 1
0 protrudes upward, and the plate spring 13 and the original fiber 8a
As a result, the original axis with respect to the original fiber 8b is shifted, and the transmission of light between the two optical fibers 8a and 8b is interrupted.

When the temperature decreases again, the coil-shaped shape memory alloy 12
The force gradually disappears and the movement returns to the previous one.

As described above, in this embodiment, a temperature rise over a certain scale can be detected by a rapid change in the presence or absence of an optical signal with a simple configuration without using a lens, and functions as an optical temperature sensor.

In this embodiment, the V-groove 9 is used as the groove in which the optical fibers 8a and 8b are placed, but any groove shape, including a U-shape, may be used as long as the groove can fix the optical fibers. Further, although only one original fiber 8a was moved out of the groove, two optical fibers 8a and 8b may be moved.

Shape memory alloy 12 used a coil shape, but 7.
7 Any shape may be used, and furthermore, the reversing plate 14 rapidly deforms when a force of a certain value or more is applied, and rapidly deforms when the force is removed or a force of a certain value or more is applied in the opposite direction. The material may be metal or plastic, and any structure may be used as long as it returns to its shape.

Effects of the Invention As described above, according to the present invention, two optical fibers can be placed in the same groove and their original axes can be made to coincide, so there is no need for optical parts such as lenses, and the number of parts is small. 1. It has the effect of not requiring base axis adjustment.

Furthermore, since the reversal plate is used to control the operation of the shape memory alloy, rapid light blocking operation can be obtained, and temperature detection can be achieved quickly.

Since the light-blocking structure is simple, it is highly reliable and can be miniaturized, making it possible to provide a light temperature sensor that is superior to conventional ones.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an optical temperature sensor according to an embodiment of the present invention, FIG. 2 is a perspective view of essential parts of an embodiment of the invention, and FIG. 3 is a sectional view of a conventional optical temperature sensor. 8a, 8b...Original fiber, 9...V groove,
1゜...Movable member, 11...Coil spring, 12...Coil-shaped shape memory alloy, 13
...Plate spring, 14...Reverse plate.

Claims (1)

[Claims] two optical fibers provided in the same groove with their end faces facing each other; a movable member that allows the tip of at least one of the optical fibers to move freely outside the groove; a shape memory alloy that controls the movement of movable members;
and an inversion plate that controls the operation of the shape memory alloy by rapidly deforming or returning to its original shape when a force exceeding a certain value is applied.