JPS5866055A - Rotation sensor - Google Patents

Abstract

PURPOSE:To enable to narrow a gap between optical fibers and improve a SN ratio, by a method wherein a jetting end surface of an optical fiber, whose one end is connected to a light source, is caused to rock following rotation of a rotary body. CONSTITUTION:Under a condition that a rotary body is brought to a stop, a permanent magnet 22 is sucked by a magnetic pole of a disc 30, and an optical fiber 4 is bent centering around a fulcrum in the proximity of a fixed jig 24, whereby light from a light source is totally reflected at an interface between the core of the optical fiber and a clad, and a given volume of light is transferred to an optical fiber 6. Meanwhile, when the rotary body starts to turn, the disc 30 turns following rotation of a shaft 28, a jetting end surface 4a of the optical fiber 4 is caused to rock centering around a fulcrum, and an aggregate area of the jetting end surface 4a and an incident end surface 6a changes. As a resut, a light volume, transferred from the optical fiber 4 to the optical fiber 6, changes, and thereby a counting value proportioning the number of revolutions of the rotary body can be obtained by counting the number of changing times of the light volume.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotation sensor, and more particularly to an improvement in a rotation sensor that detects the rotation of a rotating body from a change in the amount of light passing between a pair of optical fibers arranged at a predetermined interval.

Conventionally, a rotation sensor as shown in FIG. 1 has been known. The anode of the light emitting diode 2 is connected to the battery B via a resistor R, and the cathode of the light emitting diode 20 is grounded. A first optical fiber 4 is arranged so that one end face faces the light emitting part of the light emitting diode 2. The second optical fiber is arranged such that one end face faces the other end face of the first optical fiber 4 and the other end face faces the light receiving part of the photodiode 8.
optical fibers 6 are arranged. In the interfilO formed by the r@l optical fiber 4 and the second optical fiber 6, a photo-inotarap j12 having a number of slits drilled in the radial direction at a predetermined interval is arranged. There is. This photointerrupter 12 is connected to a rotating body.

The anode of the photodiode 8 is grounded, and its cathode is connected to the amplifier 14, the waveform shaping circuit 16 and the counter 1.
8 to the rotation speed display device 20.

According to such a conventional rotary cell, the light beam emitted by the light emitting diode 2 enters one end surface of the first optical fiber 4 and is emitted from the other end surface. At this time, when the rotating body is rotating, the photointerrupter 12 rotates with this rotation, and the light beam is intermittently incident on one end surface of the second optical fiber 6 due to the action of the slit, and is emitted from the other end surface. The photodiode 8 is irradiated with the light. Photodiode 8 is.

The irradiated light beam is converted into an electrical signal and input to the amplifier 14. The electrical signal input to the amplifier 14 is:

After being amplified by the amplifier 14 and waveform-shaped by the waveform shaping circuit 16, the wave number is counted by the counter 18.

This wave number is proportional to the rotational speed of the rotating body and is displayed on the rotational speed display device 20 as the rotational speed.

However, in such a conventional rotation sensor, optical 7 eye per 4.
Since the photo-interrupter 12 is placed between the gaps 6 and 6, the gaps 10 are wide and approximately in width.

As a result, the 8N ratio decreases. There is a problem.

The present invention was made to solve the above problems, and an object of the present invention is to provide a rotation sensor in which the gap between the optical fibers is narrowed and the S/N ratio is made benign.

One configuration of the present invention is to achieve this objective.

a first optical fiber whose one end is connected to the light source and whose exit end face swings with the rotation of a rotating body; The second optical fiber is fixed to the second optical fiber. In the present invention, in order to swing the exit end surface of the first optical fiber with the rotation of the rotating body,
Electromagnetic force and impact force from a contact piece fixed to a rotating body are used. As a result, the exit end face of the first optical fiber is swung with the rotation of the rotating body, and the rotation of the rotating body is converted into a strength signal of the light beam emitted from the light source, and the wave number of this strength signal is counted. The rotation speed of the rotating body can be found by

According to the configuration of the present invention, the distance between the optical fibers can be narrowed compared to the conventional rotation sensor.
A unique effect of improving the 8N ratio can be obtained.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows a schematic diagram of a first embodiment of the present invention.

As shown in the figure, the exit end surface 4a of the first optical fiber 4 and the entrance end surface 6a of the second optical fiber 6 are spaced apart by a predetermined distance of 10.
They are placed opposite each other. Core 4b and cladding 4c of first optical fiber 4 and core 6 of second optical fiber 6
b and the cladding 6c have the same outer diameter.

[Permanent magnets 22 are attached to the side surface near the exit end surface 4a of the first optical fiber 4 so that the magnetic poles are arranged at predetermined intervals in the circumferential direction of the first optical fiber 4.

A position a predetermined distance apart from the exit end surface 4a of the first optical fiber 4 is fixed by a first fixing jig 24. Moreover, the other end of the first optical fiber 4 is.

It is connected to a light source (not shown) in the same manner as a conventional rotating base.

On the side surface near the input end surface 6a of the second optical fiber 6,
A second fixing jig 26 is provided, and this second fixing jig 2
6 fixes the vicinity of the input end face 6m of the second optical fiber 6. Further, the other end of the second optical fiber 6 is connected to a light receiving element (not shown) as in a conventional rotational speed sensor.

A shaft 28 connected to a rotating body (not shown) is arranged parallel to the axial direction of the optical fiber 4.6.
A disk 3o made of a magnetic material and having magnetic poles arranged at predetermined intervals in the circumferential direction so as to face the magnetic poles of the permanent magnet 22 is fixed to the disk 3o. The arrangement relationship between the permanent magnet 22 and the disk 30 is shown in FIG.

The operation of one feeding will be explained below. When the rotating body is not rotating, the permanent magnet 22 is attracted to and repelled by the magnetic pole of the 3° disc, and the first optical fiber 4 is bent around the fulcrum near the first fixing jig 24. The light beam from the light source is totally reflected at the interface between the core and cladding of the optical fiber, and the light beam with a predetermined amount of light is transmitted from the optical fiber 4 of 1111 to the second light 7.
1 is transmitted to Aipa 6. Here, when the rotating body starts rotating, the disk 3o rotates as the shaft 28 rotates.

The magnetic force acting between the permanent magnet 22 and the disk 30 changes. With this change in magnetic force, the first optical fiber 4
The injection end surface 4a is swung around the fulcrum, and the injection end surface 4a
The overlapping area between the input end face 6a and the incident end face 6a is changed. As a result,
The amount of light transmitted from the first optical fiber 4 to the second optical fiber 6 changes in accordance with the change in the single polymerization area. That is, as the disk 3o, and thus the rotating body, rotates, the first light 7
The amount of light transmitted from the eyeper 4 to the second optical fiber 6 changes. Therefore, by counting the number of changes in the amount of light in the same manner as in the prior art, a count value proportional to the number of rotations of the rotating body can be obtained, and from this count value, the number of rotations of the rotating body can be determined.

FIG. 4 shows a modification of the above embodiment.

Instead of a circular plate provided with magnetic poles, a circular plate 32 is used which is provided with a large number of teeth 32m at predetermined intervals in the circumferential direction. According to this modification, the attraction force is maximized when the tips of the permanent magnet 22 and 1i 132a face each other, and the permanent magnet 22
The attraction force is at its minimum when facing aI'14. As a result, [1 optical fiber is swung around the fulcrum, and the number of rotations of one rotating body can be determined.

In addition, although the example using a permanent magnet was explained above, it is also possible to use an electromagnet instead of a permanent magnet.
Electron &a5 may be used to form the magnetic poles of the disc. First, electric force may be used instead of magnetic force.

Figure M5 shows #g2 implementation of the present invention. In this embodiment, unlike the above-described non-contact swinging of the first optical fiber,
It is made to oscillate by contact.

As shown in the figure, a disk 34 is used on which a large number of contacts 34a are fixed at predetermined intervals in the same direction.

This contactor 34g is preferably made of a flexible member. According to this embodiment, there is no need to attach a permanent magnet or the like to the tip of the ultra-thin optical fiber, so that manufacturing can be simplified.

FIG. 6 shows an example of application of the present invention. This application example is.

This is applied to vehicle speed control.

First optical fiber 4, second optical fiber 6, permanent magnet 2
2. The rotary entertainment center, including the disc 30 and the shaft 28, is housed within the housing 36. -mK of the shaft 28 is fixed with a driven gear 40 connected to a gear of a transmission. Further, the other end of the shaft 28 is supported by a bearing 42 and a bearing 44. Furthermore, approximately the center of the shaft 28 is sealed with an oil seal 38, and the rotational
This prevents dust from getting into the water.

The present invention can be applied to crank angle sensors and the like in addition to the vehicle speed sensor described above.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a conventional rotating unit, Fig. 2 is an explanatory diagram showing a first embodiment of the present invention, and Fig. 3 is a schematic diagram showing the arrangement of permanent magnets and discs in the present invention. FIG. 5 is a plan view similar to FIG. 3 showing the second embodiment of the present invention, and FIG. 6 is a plan view similar to FIG. FIG. 2 is a sectional view showing an example of application of the present invention. 4... First optical fiber, 4a... Output end face 6... Second optical fiber, 6a... Input end face, 22... Permanent magnet, 2
4.26...Fixing jig, 30...Disc. -2= Fig. 3 4 Uul 5 r2J and 561.・1

Claims (2)

[Claims] (1) a light source, a first optical fiber whose one end is connected to the light source and whose exit end surface swings with the rotation of a rotating body; and a second optical fiber fixed so as to face the emission end surface. (2) The rotating unit according to claim 1, wherein the exit end face of the first optical fiber is swung by an electromagnetic force that changes with the rotation of a rotating body.