JP2841612B2 - Displacement detection sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a displacement detection sensor that optically detects the presence or absence of a displacement of an object to be detected.

[Prior Art] As one of optical displacement detection sensors, the one shown in FIG. 3 has been proposed.

In FIG. 3, reference numeral 3 denotes a cylindrical drum, and shafts 18 at both ends of the drum 3 are rotatably supported by the main body housing 4 and the reflection mirror 7 via bearings 13, respectively. The drum 3, the main body housing 4, and the reflection mirror 7 are housed and fixed in the case 2, and are all made of a non-magnetic material such as Al or an Al alloy. Light emitted from a light emitting element (not shown) outside the case 2 is guided by an optical fiber 12a, and is converted into parallel incident light 8 by a rod lens 5a via an FC type optical connector 10a and a receptacle 11a. In the position, the light passes through the through hole 16 of the drum 3 and is reflected by the mirror 7. The reflection holes 19 and 20 reflected by the mirror 7 pass through the other through holes 17 of the drum 3 and are condensed by the rod lens 5b, and then connected to the optical fiber 12b connected via the receptacle 11b and the FC connector 10b. The light enters, is guided to the outside of the case 2 by the optical fiber 12b, and is received by a light receiving element (not shown).

Reference numeral 1 denotes an external magnet attached to a displacement detection target or an object to be detected. The external magnet 1 moves almost linearly from 1A to 1B as the object to be detected is displaced. The drum 3 is installed such that its rotating shaft 18 is parallel to the moving direction of the external magnet 1 and at an appropriate distance. The outer peripheral surface of the drum 3 is spirally wound with iron tape 9 at a constant pitch.
Is installed.

Next, the operation of rotating and shielding the drum 3 with the movement of the external magnet 1 will be described with reference to FIG. When the external magnet 1 moves from 1A to 1B in the direction of the rotation axis of the drum 3 with the displacement of the object to be detected, the magnetic force of the external magnet 1 attracts the drum 3
The portion of the iron tape 9 spirally attached to the outer magnet 1 is strongly attracted and pivots from 9A to 9B. That is, the drum 3 rotates. Thereby, the through holes 16A, 17
A rotates to 16B, 17B, through holes 16, 17 and rod lenses 5a, 5b
Are no longer opposed, and the paths of the lights 8, 19 and 20 are blocked. Conversely, when the external magnet 1 moves from 1B to 1A, the drum 3 reverses, the through holes 16, 17 and the rod lenses 5a, 5b face each other, and the light 8,1
9,20 routes are opened and connected. The amount of light received by the light receiving element fluctuates due to the continuation of the optical path by the drum 3, and the presence or absence of displacement of the detection target is detected.

[Problem to be Solved by the Invention] In the displacement detection sensor proposed above, since the iron tape 9 is spirally mounted on the outer peripheral surface of the drum 3, the rotation axis of the drum 3 is parallel to the moving direction of the detection target. Sensors must be installed so that For this reason, for example, when a plurality of the above-mentioned sensors are used in order to detect the upper limit and the lower limit of the movement amount of the detection object, the size becomes large, and it is difficult to apply the sensor to a narrow space.

Also, since the external magnet 1 and the iron tape 9 are attracted at one point and the drum 3 is rotated by this attractive force, the external magnet 1
When the distance between the sensor and the sensor increases, the attraction force may decrease and switching may not be performed, so that the installation and adjustment of the external magnet 1 and the sensor may be delicate. Further, in such magnetic attraction, there is a limit to shortening the helical pitch of the iron tape 9 in order to reduce the axial dimension of the drum 3, and if the amount of movement of the object to be detected is small, displacement detection is not possible. It tends to be impossible.

Further, there is a problem that it is difficult to attach the iron tape 9 to the outer peripheral surface of the drum 3 in a spiral at a predetermined pitch and the cost is increased.

An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art,
An object of the present invention is to provide a displacement detection sensor that is small, has good detection sensitivity, and is easy to install.

[Means for Solving the Problems] A displacement detection sensor according to the present invention includes: an external magnet attached to an object to be detected, which linearly moves in accordance with the linear motion displacement of the object to be detected, and a moving direction of the external magnet. A rotation axis is arranged in a direction substantially perpendicular to the rotation direction, and a light-shielding body that interrupts an optical path from the light-emitting element to the light-receiving element by the rotation thereof, and an iron provided on the outer surface of the light-shielding body in a band shape along the rotation axis direction. A tape is provided, and the light-shielding body is rotated by magnet attraction between the iron tape and the external magnet to detect the displacement of the linear motion of the detection target.

As the light shielding body, for example, a cylindrical body having a hole serving as an optical path is used.

The iron tape provided in a belt shape includes an iron tape provided in a linear shape.

[Operation] When the external magnet moves in a direction substantially perpendicular to the rotation axis of the light shield with the displacement of the object to be detected, the iron tape provided on the outer surface of the light shield is attracted by the magnetic force of the external magnet, Moves following the external magnet. This movement rotates the light shield, and opens or closes the optical path from the light emitting element to the light receiving element. Therefore, the optical signal input to the light receiving element is turned on / off, and the presence or absence of the displacement of the detection target is detected.

Here, the iron tape is provided on the outer surface of the light shield in a band along the rotation axis direction, and the entire magnet strip is attracted by the movement of the external magnet, so that the light shield rotates. Unlike the case where the light shield rotates by moving a part of the spiral iron tape so that it is closest to the external magnet, the length of the strip of iron tape is directly Since it does not contribute, it may be short, and therefore the axial thickness of the light shield provided with the strip-shaped iron tape may be small.

Also, when trying to make the light-shielding body thinner in the axial direction in order to reduce the size of this sensor, if the iron tape is helical and a part of it is attracted, the detection sensitivity will decrease as the pitch becomes narrower. However, as in the present invention, the entire belt-like iron tape is attracted,
Even if the light shield is made thin, the detection sensitivity does not decrease.

In addition, since the moving direction of the external magnet is orthogonal to the rotation axis of the light shield, when installing a plurality of the sensors in the moving direction of the external magnet, the sensor is not arranged in series in the rotation axis direction but in parallel with the rotation axis direction. It can be installed.

Example An example of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a disk-shaped external magnet attached to the object to be detected, and the external magnet 1 moves almost linearly from 1A to 1B as the object to be detected is displaced. Reference numeral 2 denotes a case in which the sensor body is stored.
A cylindrical drum 3, a main body housing 4, a reflection mirror 7, and the like are housed, all of which are made of a nonmagnetic material such as Al or an Al alloy. The shafts 18 at both ends of the drum 3 are rotatably supported by the main body housing 4 and the reflection mirror 7 via bearings 13, respectively. The rotation axis of the drum 3 is disposed so as to be substantially perpendicular to the moving direction (1A1B) of the external magnet 1 and at an appropriate distance from the external magnet 1. On the outer peripheral surface of the drum 3, an iron tape 21 is attached in a belt shape along the rotation axis direction. It should be noted that the thickness of the illustrated drum 3 is smaller than that of the conventional drum.

The drum 3 also has two through holes 1 parallel to the rotating shaft 18.
6,17 are formed. The through holes 16 and 17 can face the rod lenses 5a and 5b at predetermined rotation positions of the drum 3, respectively, and the rod lenses 5a and 5b can be optically connected via the reflection mirror 7. The rod lens 5a has a receptacle
11a, one end of the optical fiber 12a is coupled via the FC type optical connector 10a, and the rod lens 5b also has a receptacle 11b,
One end of an optical fiber 12b is connected via an FC-type optical connector 10b. The optical fibers 12a and 12b are led out of the case 2 by a waterproof connector 6 in a liquid-tight state.
A light emitting element (not shown) is provided at the other end of the optical fiber 12a, and a light receiving element (not shown) is provided at the other end of the optical fiber 12b. An upper lid 15 is detachably and liquid-tightly attached to an upper opening of the case 2 by a set screw 14.

Next, rotation of the drum 3 due to movement of the external magnet 1 and opening and closing of the optical path between the rod lenses 5a and 5b will be described with reference to FIG.

When the external magnet 1 is at 1A, the rod lens
5a, 5b and the through holes 16A, 17A face each other. Therefore, the light emitted by the light emitting element passes through the optical fiber
At a, the incident light 8 becomes parallel light 8, passes through the through hole 16A, is reflected twice by the reflecting mirror 7, and the reflected light 20 is coupled to the rod lens 5b through the through hole 17A and guided to the optical fiber 12b. The light is received by the light receiving element.

Now, when the external magnet 1 moves from 1A to 1B in the direction orthogonal to the rotation axis 18 of the drum 3 with the displacement of the object to be detected, the strip-shaped iron tape 21 mounted in the axial direction of the drum 3 is moved. It is attracted by the magnetic force of the external magnet 1 and moves following the external magnet 1. The drum 3 is rotated by the movement of the iron tape 21 by the attraction force of the external magnet 1. When the drum 3 rotates, the through holes 16A and 17A move to 16B and 17B, and the through holes 16B and 17B no longer face the rod lenses 5a and 5b. Therefore, light 8,19,
The optical path 20 is blocked by the drum 3 so that no light enters the light receiving element. On the contrary, the external magnet 1 is
When the drum 3 moves from 1B to 1A, the drum 3 rotates in reverse with the iron tape 21, and the through holes 16A and 17A face the rod lenses 5a and 5b,
The paths of the lights 8, 19, and 20 are opened, and light from the light emitting element enters the light receiving element. Therefore, the presence or absence of the displacement of the detection target can be detected from the on / off signal of the light incident on the light receiving element.

As described above, according to the present embodiment, the shaft of the drum is arranged in a direction substantially perpendicular to the direction of movement of the external magnet accompanying the displacement of the object to be detected, and provided on the outer surface of the drum in parallel with the shaft direction. Due to the magnetic attraction between the band-shaped iron tape and the external magnet, the movement of the external magnet is displaced to the rotation of the drum, and the displacement is detected. For this reason, unlike the conventional method in which the shaft of the drum is arranged in parallel to the movement direction of the external magnet and the movement of the external magnet is converted into drum rotation, the drum thickness in the shaft direction for conversion is unnecessary. Therefore, the sensor size in the direction of the shaft of the drum can be shortened,
The size of the sensor can be reduced. Furthermore, even when a plurality of the present sensors are installed in the moving direction of the external magnet, unlike the conventional one in which the sensors are installed in series in the shaft direction, they can be installed in parallel with the shaft direction. It can be easily stored in space.

Also, instead of detecting the movement of the external magnet in the direction parallel to the drum shaft as in the conventional method, the system detects the movement of the external magnet in the direction perpendicular to the drum shaft, so the displacement of the object to be detected is small. Even small is detectable,
Detection sensitivity can be improved.

Furthermore, since the external magnet and the strip-shaped iron tape on the outer surface of the drum attract linearly, even if the distance between the external magnet and the sensor is slightly larger than that of the conventional one that attracts in a point-like manner, There is little reduction in the attractive force, the installation and adjustment of the external magnet and the sensor become easy, and the reliability can be improved without malfunction.

Further, since a strip-shaped iron tape is simply mounted in the direction of the shaft of the drum, processing and mounting are easier and cost is reduced as compared with a conventional spiral iron tape.

[Effects of the Invention] According to the present invention, a light shield is provided by attracting an iron tape provided in parallel with the rotation direction of the light shield by the movement of an external magnet that moves in a direction substantially perpendicular to the rotation axis of the light shield. Because it is rotated, the external magnet that moves parallel to the axis of rotation of the light shield pulls the spirally provided iron tape to rotate the light shield. Good sensitivity and easy installation.

[Brief description of the drawings]

1 is a plan sectional view showing one embodiment of a displacement detection sensor according to the present invention, and FIG. 2 is for explaining the operation of the sensor. FIG. 1 (a) is a plan view and FIG. (B) is a side view, FIG. 3 is a plan sectional view of a conventional displacement detection sensor, and FIG.
The drawings are for explaining the operation of the sensor, and FIG. 14A is a side view and FIG. 14B is a side view. 1 is an external magnet attached to an object to be detected, 2 is a case,
3 is a drum as a light shield, 4 is a main body housing, 5a, 5
b is a rod lens, 6 is a waterproof connector, 7 is a reflection mirror, 8 is incident light, 9 is an iron tape, 10a and 10b are FC connectors, 11a and 11b are receptacles, 12a and 12b are optical fibers, 13
Is a bearing, 14 is a set screw, 15 is an upper lid, 16 and 17 are through holes, 19 is a shaft which is a rotating shaft, 19 and 20 are reflected light, and 21 is an iron tape.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 11/00-11/30 G01D 5/26-5/38

Claims (1)

(57) [Claims] An external magnet attached to the object to be detected and moving linearly in accordance with the displacement of the linear movement of the object to be detected, and a rotation axis arranged substantially perpendicular to the direction of movement of the external magnet. A light-shielding body that interrupts an optical path from the light-emitting element to the light-receiving element by the rotation thereof, and an iron tape provided on an outer surface of the light-shielding body in a band along the rotation axis direction, A displacement detection sensor for detecting a displacement of a linear motion of a detected body by rotating the light shielding body by magnetic attraction with the external magnet.