JPH0690050B2 - Optical displacement sensor - Google Patents

Description

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

[Prior Art] Various sensors have been proposed in the past as a sensor for detecting the positional displacement of a displaced or moving object.

The optical displacement detection sensor differs from the conventional one that uses an electrical contact method such as a limit switch, etc., and because the detection means is a non-contact type, there is no problem of contact part wear and the life is greatly extended. It has many advantages such as being able to contribute to the improvement of reliability as well as being able to obtain reliability as well as being less likely to malfunction due to induction and noise, and has recently attracted attention with the progress of optical related systems. .

19 to 21 show three embodiments of this kind of conventional optical displacement sensor.

FIG. 19 shows an example in which the prism 4 is used for reflecting light, and the light emitted from the light emitting element (not shown) is guided by the optical fiber 1a and emitted by the rod lens 2 as parallel light. 3a is reflected by the prism 4 to form reflected light 3b, which is input from the rod lens 2'and the optical fiber 1a '
The light is received by a light receiving element (not shown) via the. The light path portion of the reflected light 3b is provided with a light shielding plate 5 which is displaced in the direction of the arrow in the figure according to the displacement of the detection object (not shown), and the light shielding plate 5 is displaced to move to the dotted line position. The optical path of the reflected light 3b is blocked by and the displacement of the detected object is detected by detecting the presence of the reflected light 3b by opening the optical path of the reflected light 3b by displacing again and returning to the solid line position. Detect.

FIG. 20 shows an arrangement in which two reflecting mirrors 6 and 6'having a reflection surface of 45 ° are installed in place of the prism 4 shown in FIG.
In the case of this embodiment, the shading plate 5 is provided between the two reflecting mirrors 6 and 6 '.
Is arranged so that the optical path between the reflecting mirrors can be blocked, and it is selected when it is more efficient to install the light shielding plate 5 in such a position depending on the sensor installation conditions.

Further, FIG. 21 shows still another embodiment, in which two optical fibers 1a and 1a ′ are arranged in an end face butted state, and when both the optical fibers 1a and 1a ′ are on the same line, the conduction of light does not occur. Be configured as possible. Here, when an external force P is applied by the displacement of the object to be detected, the optical fibers 1a and 1a 'are configured so that the axes are displaced as shown by the dotted lines so that the light is not conducted. The displacement of the object to be detected is detected.

However, the conventional sensor shown in FIGS. 19 to 21 has the following problems.

First, there is a problem that the displacement movement of the light shielding plate 5 is performed by mechanical contact with the detected body. Certainly, the displacement detection means is performed in an optical non-contact state, but if the light shielding plate is moved by a contact method, it will not change much from the conventional electrical contact method and wear of the contact part is unavoidable. However, it is still difficult to avoid the risk of malfunction.

Second, it is often desirable to store the sensor part in the case in order to protect the sensor part from dust, humidity, external force, radiation, etc. There is a problem that it cannot be completely sealed.

Further, with the method shown in FIG. 21, it is easy to cause an axis deviation of the optical path, but it is difficult to restore this to the original position. Moreover, even if the curvature is large, it is not preferable to repeatedly bend the optical fiber as described above in terms of material fatigue.

In order to solve the above-mentioned problems, the applicant first stored the sensor portion in a case capable of being completely sealed, and the movement of the light shielding body was performed by moving the light shielding body to a magnetic body on the light shielding body by an external magnet outside the sealed case. We have proposed an optical displacement sensor that is configured so that it can be induced by the movement induction of. (Japanese Patent Application Sho 63-6223
4) FIG. 18 is a sectional view showing a specific example of the optical displacement sensor according to the proposal.

Arranged in a sealed case 9 made of a non-magnetic material are two receiving mirrors 6 and 6'for reflecting light emitted from and emitted from the light emitting and receiving ends 2 and 2a in a direction parallel to the emitted light 3a. At least a part of the light shield 5 housed in the closed case 9 has a ferromagnetic body 7 and is movable back and forth in a direction parallel to the emitted / reflected light. The light-shielding piece 5a is constructed so as to shield light between the two reflecting mirrors 6 and 6 ', and when the detected body is displaced, the external magnet 8 outside the hermetically sealed case does not contact the case. It is configured so that displacement movement can be induced in the ferromagnetic body 7 of the light shield 5 inside.

[Problems to be Solved by the Invention] According to the hermetically-sealed displacement detection sensor described above, since displacement is detected in a non-contact state, long-term stability can be established because there is no wear, and it is housed in a hermetically sealed case. With this, it is possible to maintain the accuracy by preventing dust and moisture, and there is a great merit that external noise can be sufficiently eliminated.

However, the basic configuration is to displace the external magnet 8 to induce the light-shielding body side magnetic body 7 to be displaced, thereby causing the light-shielding body 5 to move.
However, if the displacement of the external magnet 8 is within a certain range, there is no problem.
Is no longer within the range of the binding force of the external magnet 8,
The light-shielding body 5 is in a state in which it moves halfway freely due to vibrations from the outside, which may result in a great decrease in reliability as a sensor.

An object of the present invention is to solve the above-mentioned problems, and in a displacement detection sensor that moves a light shield by an external magnet to detect the displacement of an object to be detected, the external magnet restrains the light shield side magnetic body. It is intended to provide a new optical displacement detection sensor that does not cause the internal light shield to move arbitrarily even if it moves beyond the obtainable range,
Further, another object of the present invention is to provide an optical displacement detection sensor in which the reflection / reflectance system is improved so that the reflection of the optical path in such an optical sensor can be simplified and only one reflection is required.

[Means for Solving the Problems] In the present invention, an internal magnetic body or a magnet is separately arranged between an external magnet and a light shielding body side magnetic body or a magnet, and the displaced light shielding body side magnetic body is attracted by the internal magnetic body or the magnet. It is designed so that it can be locked.

At this time, lock magnets are preferably installed on both sides of the moving range of the internal magnetic body or the magnet.

Also, regarding the optical path blocked by such a light shield,
The lens for receiving light has an angle so that the reflected light from one reflecting surface can be directly received by the light receiving lens, thereby simplifying the structure.

[Operation] If the internal magnetic body or the magnet is configured to move within a certain range in accordance with the movement of the magnetic body on the side of the light shield, the external magnet moves largely and deviates from the range where the light shield can be restrained. However, the light shielding body in which the internal magnetic body or the magnet is displaced is locked in the displaced state. When the external magnet returns to its original state, the light shield also returns to its original state, and malfunction is prevented. By providing magnets capable of temporarily locking the internal magnetic body or the magnet on both sides of the moving range of the magnet, the malfunction preventing effect can be further ensured.

[Examples] Hereinafter, the present invention will be sequentially described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention.

1,1 'is an optical fiber kale with an optical fiber inside, 1
0,10 'is a connector attached to the end of the optical fiber cable, 11,11' is a receptacle paired with the connector 10,10 ', 12 and 12' is an end of the optical fiber in the receptacle 11,11 '. It is a rod lens provided in.

Light emitted by a light emitting element (not shown) is emitted as parallel emission light 3a from the rod lens 12 via the optical fiber of the optical fiber cable 1. 45 ahead of the outgoing light 3a
There is a first reflecting mirror 6 having a reflecting surface in the direction of °, and the light whose direction is changed by 90 ° by the reflecting mirror 6 is again changed by 90 ° by the second reflecting mirror 6 ', and emitted light 3a and All of the parallel reflected light 3b enters the rod lens 12 'and is received by a light receiving element (not shown) via the optical fiber cable 1'.

On the other hand, in this embodiment, there is a light shield 5 which can move back and forth in a direction parallel to the outgoing / reflected light 3a, 3b, and a part of the light shield 5 is formed on the light shield 5a, and the light shield 5a is shown in FIG. The optical path between the reflecting mirrors 6 and 6'can be cut off by displacing to the position of the middle dotted line. Reference numeral 13 is a holder for holding the light shield 5, and reference numeral 7 is a ferromagnetic material or a magnet (hereinafter simply referred to as a magnetic material) attached to the outer surface of the light shield 5. Outside the magnetic body 7, there is a separate external magnet 8 attached to the side of the detected body (not shown), and the external magnet 8 moves as indicated by the dotted line 8'in FIG. 1 due to the displacement of the detected body. The magnetic body 7 on the light shield 5 side is attracted and moved in a non-contact manner, whereby the light shield piece 5a is moved, and the optical path between the reflecting mirrors 6 and 6'is blocked as shown by the dotted line in FIG. To be configured.

Therefore, in the present invention, there is a separate inner magnetic body (or magnet) 14 between the light-shielding body side magnetic body 7 and the outer magnet 8, and the inner magnetic body (or magnet) 14 is tracked as the outer magnet 8 moves. The magnet) 14 is also configured to be movable within a certain range.

Regarding the selection of whether the light-shielding body side magnetic body 7 is made of a ferromagnetic body or a magnet, or whether the internal magnetic body 14 is made of a ferromagnetic body or a magnet, the above operation should be carried out smoothly. You can choose to. Therefore, in the following, the internal magnetic body or magnet 14 will be referred to simply as the internal magnetic body 14
However, it goes without saying that it includes the selectivity with respect to the magnet as described above.

FIG. 3 is an explanatory cross-sectional view for explaining the relationship between the behavior of the magnetic bodies 7 and 14 and the external magnet 8 in more detail.

When the external magnet 8 moves to 8'shown by the dotted line, the light-shielding body side magnetic body 7 and the internal magnetic body 14 also move to 8'shown by the dotted line. Therefore, it is assumed that the external magnetic body 8 is moved further in the direction of the white arrow. Conventionally, there is no longer any means for restraining the magnetic material 7 on the light-shielding body side, the magnetic material 7 is in a so-called dangling state, and can freely move due to vibrations from the outside. Therefore, if the light blocking body 5 moves and the light blocking state is released, the reliability of the sensor will be greatly impaired.

In the sensor according to the present invention, even if the external magnet 8 largely moves, the internal magnetic body 14 still remains at that position, and the light shield side magnetic body 7 continues to operate at high speed.
In other words, the magnetic body 7 is temporarily locked.

After that, when the external magnet 8 returns and returns to the original position, the light shielding body side magnetic body 7 is returned to the original position together with the internal magnetic body 14, and the light blocking by the light shielding piece 5a is released.

From the above, the reliability as the displacement sensor is sufficiently established.

Since it is necessary for the internal magnetic body 14 to be able to move within a certain range as described above, it is necessary to coat the sliding portion with Teflon or to dispose an appropriate material that reduces the friction coefficient in order to improve sliding. Is preferred.

It is desired that the inner magnetic body 14 has good slipperiness as described above, but in a state where the outer magnet 8 moves to 8 ″ as shown in FIG. However, there is a risk that the slippery inner magnetic body 14 may move due to vibrations and the like, which may cause a malfunction of the light shield 5. In order to prevent this, as shown in FIGS. Locking magnets 18,18 'on both sides
Should be provided.

By disposing the locking magnets 18 and 18 ', even if the external magnet 8 moves excessively and the constraint force against the internal magnetic body 14 is not exerted, the internal magnetic body 14 is locked by the magnets 18 or 18 for locking. It is possible to prevent the internal magnetic body 14 from moving due to the locking of ′. Locking magnet 18,18 '
Since it has the above-mentioned action, when a magnet is used as the internal magnetic body 14, the locking magnets 18 and 18 'are not limited to magnets and a ferromagnetic material can be used. is there. Therefore, it goes without saying that the expression "locking magnet" includes the case where such a ferromagnetic material is used.

FIG. 5 is an explanatory diagram showing an example in which the sensor according to the present invention is applied to position detection of an object within a distance L. The sealed cases 9 and 9'are set apart by a distance L, and the external magnet 8
Is moved from the solid line in FIG. 5 to the dotted line along the outer peripheral surface of the closed case 9, 9 '.
The optical path is blocked and the optical path is conducted inside, and the position of the moving object can be detected by the change. It is also possible to install the required number of cases 9 and then detect the movement of the moving body.

FIG. 6 shows another embodiment of the displacement sensor according to the present invention, and shows an example in which the external magnet 8 and the internal magnetic body 14 are arranged in a part of the case 9. As such, these do not necessarily have to be arranged all around. Also in this case,
If desired, it is preferable to arrange locking magnets 18, 18 'as shown in FIG.

In the embodiment shown in FIG. 1 above, a pair of reflecting mirrors 6 and 6'is installed and the optical path is reflected by 90 degrees each, but two reflecting mirrors are installed in pairs. This means that it requires a large amount of space, resulting in a large size and complicated axis alignment.

FIGS. 8 to 15 show respective embodiments according to the present invention in which one reflecting mirror is used and light can be emitted and received by one reflecting mirror.

In the present invention, either one or both of the collimating lenses 12 and 12 'attached to the ends of the optical fibers 1 and 1'have an angle or a curvature so as to match the incident / reflection angle of one reflecting mirror 6. It is configured such that light can be emitted and incident in directions, and an optical path can be formed by one reflecting mirror 6 without using two reflecting mirrors. Therefore,
It goes without saying that the technical idea of the present invention is not limited to the case where the external magnet 8 is installed, but can also be applied to the sensor having the conventional structure as shown in FIG.

Therefore, in FIG. 8, one lens 12 is angled, and at the same time, the reflecting mirror 6 is also angled so that the light emitted by the emitting lens is reflected by the reflecting mirror 6 only once, and the condensing lens 12 is immediately turned on. An example is shown in which the light is focused on ′. In FIG. 8, 5 is a light shield (in the drawings of the following embodiments, the light shield side magnetic body 7 is not shown, but the movement of the light shield is not different from the above), 8 is an external magnet, and 14 is an internal magnet. It is a body, and light is conducted and blocked by moving as shown by arrows.

FIG. 10 is a longitudinal sectional view showing another embodiment, and FIG. 11 is a transverse sectional explanatory view thereof. In the present embodiment, the external magnet 8 and the internal magnetic body 14 are arranged directly below the light shield 5 to facilitate the interlocking of the light shield 5 with the object to be detected.

FIG. 13 shows another embodiment, in which not only the exit lens 12 but also the condenser lens 12 'have an angle, and the reflecting mirror 6 is installed parallel to the wall surface of the case 9 without an angle. It is a thing. The assembly of the device can be simplified without the need to adjust the reflector.

In any of the above embodiments, as shown in FIG. 12 and FIG. 14 which are sectional views taken along the line AA of FIG. 9 or FIG. 11, the locking magnets 18, 18 are provided on both sides of the moving range of the internal magnetic body 14. 1
By disposing 8 ', the above-mentioned internal magnetic body 14 can be locked.

FIG. 15 is a cross-sectional explanatory view showing another embodiment in which the sensor shown in FIG. 13 is used to form a sensor having another light shield 5.

In the present embodiment, the light shield 5 is not configured to completely block light as in the previous embodiments, but is configured to allow partial light transmission.

FIG. 16 (a) is a perspective view showing an embodiment of such a light shield 5, and the attenuated transmission in which the emitted light 3a is attenuated and transmitted to the light shield 5 which is guided by the shaft 15 and can move back and forth as shown by an arrow. The window T is formed by the length l. The transmission window T is configured so that the attenuation amount α of light continuously changes from one end to the other end of the length 1 as shown in FIG. 16B, and the displacement is detected by detecting the attenuation amount. It is structured so that the quantity can be known. That is, if the object to be detected is a valve, it is possible to monitor the state of the valve such as fully open, half open, fully closed, or in the middle thereof according to the amount of attenuation.

FIG. 17A shows another embodiment of the light shield 5.
An example is shown in which the attenuation windows are arranged at intervals such as A, B, C, D, E, F, ... Instead of the continuous attenuation windows.

In this embodiment, as shown in FIG. 17B, each window A, B, C, D, F,
Although the case where the attenuation amount α of F, is the same is shown, this attenuation amount may be different. The displacement can be easily monitored even by such an intermittent window.

Furthermore, in the sensor of FIG.
There is provided a partition member 16 which can pass through the pass-through window 17 'of 17 and the reflected light 3b and optically separate the collimator lenses 12, 12' side from the reflecting mirror 6 side. This prevents the light reflected by the light shield 5 from entering the light-receiving side and causing a malfunction due to the reflected light when the light is shielded by the light shield 5, thereby significantly improving the reliability of the sensor. It is a thing. Therefore, in order to further reduce the scattering of the reflected light, it is more preferable that the inside of the case 9 is subjected to appropriate diffused reflection prevention treatment such as matte coating.

Such a partition member 16 is not particularly shown in other embodiments, but it is needless to say that it can be widely applied to other than the embodiment shown in FIG.

[Effects of the Invention] As described above, according to the displacement detection sensor of the present invention, since displacement movement can be detected in a non-contact state with respect to the object to be detected, there is no damaged portion due to abrasion, etc. There is no failure as seen, the stable state is maintained for a long time, and not only the reliability is greatly improved, but also
Since it is a non-contact type, the entire detection system can be housed in a sealed case, dust and moisture can be prevented, and light is shielded even if the external magnetic body moves greatly and the binding force is not reached. It has a great industrial significance, such as the possibility of causing a malfunction in the body.

[Brief description of drawings]

1 and 2 are cross-sectional views of an embodiment according to the present invention, FIG.
4 and 5 are longitudinal sectional views showing the operation thereof, FIG. 5 is an explanatory view showing an example in which the embodiment according to the present invention is applied to position detection of a moving body, and FIGS. 6 and 7 are vertical cross sections showing another embodiment. FIGS. 8 and 9 are transverse sectional explanatory views showing another embodiment, FIG. 10 is a longitudinal sectional explanatory view showing another embodiment, and FIG. 11 is a transverse sectional explanatory view of FIG. The drawing is a sectional view taken along the line AA of FIG.
FIG. 16 is a cross-sectional explanatory view showing another embodiment, FIGS. 16 and 17 are perspective views showing two different embodiments of the light shield and attenuation diagrams of transmitted light, and FIG. 18 is a concrete example of the already proposed sensor. And FIG. 19 to FIG. 21 are explanatory views showing a configuration of a conventional optical displacement sensor. 1,1 ': Optical fiber, 3a: Emitted light, 3b: Reflected light, 5: Light shield, 5 ₁ : Slit, 5a: Light shield, 6,6': Reflector, 7: Light shield side magnetic material, 8: External magnet, 9: hermetically sealed case, 2, 2 ', 12, 12': rod lens, 14: internal magnetic material, 18, 18 ': locking magnet.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeo Okada 5-1-1, Hidaka-cho, Hitachi-shi, Ibaraki Hitachi Cable Co., Ltd. Hidaka factory (56) Reference JP-A-59-147290 (JP, A) ) JP-A-55-52910 (JP, A) JP-A-50-149025 (JP, A) JP-A-61-118613 (JP, A) Actual development Sho-60-68473 (JP, U)

Claims (4)

[Claims] 1. A light shield, which is movable according to the displacement of a detected object, is arranged in the middle of an optical system path for receiving light emitted from a light emitting element by a light receiving element, and at least a part of the light shield is strengthened. A displacement detection sensor comprising a magnetic body or a magnet, wherein the movement of the light shield due to the displacement of the detected body can be performed in a non-contact manner by an external magnet separately provided on the detected body side, An optical displacement sensor comprising an internal magnetic body or a magnet, which can move within a certain range according to the movement of the external magnet, between the external magnet and the magnetic body on the side of the light shield or the magnet. 2. The optical displacement according to claim 1, wherein a magnet or a ferromagnetic material capable of temporarily locking the inner magnetic body or the magnet is arranged on both sides of a range in which the inner magnetic body or the magnet can move. Sensor. 3. The optical displacement sensor according to claim 1, wherein the light shielding body is provided with an attenuating portion for attenuating the incident light continuously or intermittently at a position where the light path is blocked. 4. One or both of the collimating lenses for emitting and receiving light have an angle or a curvature, and the light emitted from the light emitting element side lens is reflected by one reflecting surface to receive the reflected light as it is. The optical displacement sensor according to claim 1, wherein the element side lens is configured to be capable of receiving light.