JPH05141960A - Optical rotation angle detecting device - Google Patents

Abstract

PURPOSE:To provide a small-sized optical rotation angle detecting device having a long life and capable of precisely detecting the rotation angle regardless of the magnitude of the detection angle. CONSTITUTION:An optical fiber 29 faced with its incidence end face to a light source 25 arranged on the rotation center axis of a rotary member 28 rotated interlockingly with a rotary shaft 23 is supported on the rotary member 28. The radiation end face of the optical fiber 29 is located near and faced to the light reception section of a light position detecting element 27 circularly arranged centering on the rotation center axis of the rotary member 28, and a condensing means is provided on either one or both of the incidence face side and radiation end face side of the optical fiber 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical rotation angle detection device, and more particularly to an optical position detection type optical rotation angle detection device using an optical position detection element as a light receiving element.

[0002]

2. Description of the Related Art In recent years, in order to detect the rotation angle of an object with high durability and reliability, a rotation angle detection device using a variable resistor utilizing electrical contact has been replaced by Japanese Patent Laid-Open No. 61- No. 246620 and Japanese Patent Laid-Open No. 61-12482.
The light radiated from the rotating object or reflected and transmitted by the rotating object as shown in Japanese Patent No. 1 is received by an optical position detecting element provided with a resistance layer, and the light receiving position of the optical position detecting element causes non-contact. Optical rotation angle detection devices have been used to detect the rotation angle of a rotating object.

These conventional optical rotation angle detectors are constructed as shown in FIGS. 13 and 15, respectively. That is, in FIG. 13 showing the optical rotation angle detecting device disclosed in Japanese Patent Laid-Open No. 61-246620, 1 is a rotating shaft connected to a rotating object (not shown), and 2 is an interlocking with the rotating shaft 1. Each of the rotating slit plates is shown. The rotating slit plate 2 is formed with a spiral slit 2a whose radius changes according to its rotation angle.

A light source 3 and an optical position detecting element 4 are arranged on both sides of the rotary slit plate 2 so as to extend in the radial direction of the rotary slit plate 2 with a light emitting portion and a light receiving portion, respectively. A fixed slit plate 5 is arranged on the optical axis of the light source 3. The fixed slit plate 5 is formed with a fixed slit 5a which is parallel to the light receiving portion of the optical position detection element 4 and intersects with the spiral slit 2a of the rotary slit plate 2.

From the optical position detecting element 4, three lead wires 6 are provided.
Outputs a, 6b, and 6c are connected to each circuit forming the detection circuit 7. That is, the detection circuit 7 includes current-voltage conversion circuits 7a and 7b.
The current outputs i ₁ and i ₂ from the leads 6a and 6c of the optical position detecting element 4 are input to each of 7b. The detecting circuit 7 further includes an adding circuit 7c, a comparing and integrating circuit 7d, a light emitting circuit 7e and an amplifying circuit 7f.

According to such an optical rotation angle detector, the light source 3 rotates the light by the light emitting circuit 7e.
When projected in the direction of, only the light of the projected light that passes through the intersection region of the spiral slit 2a of the rotary slit plate 2 and the fixed slit 5a of the fixed slit plate 5 reaches the light position detection element 4. Therefore, when the rotary slit plate 2 rotates in conjunction with the rotary shaft 1, the intersecting region moves in the radial direction, and the light receiving position on the optical position detection element 4 moves in the radial direction to rotate the rotary slit plate 2. Since it changes depending on the rotation angle of
The rotation angle of the rotary shaft 1 can be detected by detecting the light receiving position.

As shown in FIG. 14, this optical position detecting element 4 holds a photoelectric conversion layer 4a between a transparent resistance layer 4b and a bias electrode 4c, and a detection electrode 4d is provided at both ends of the transparent resistance layer 4b.
And a detection electrode 4d.
Leads 6a and 6c are connected to the bias electrode 4
A predetermined bias potential (here, the case of grounding is shown) is applied to c from the lead 4b.

When a light beam enters the optical position detecting element 4, the incident light beam passes through the transparent resistance layer 4b and the photoelectric conversion layer 4
The photoelectric currents i ₁ and i ₂ are photoelectrically converted by a and flow through the transparent resistance layer 4b toward the detection electrodes 4d at both ends thereof. At this time, the magnitudes of the currents i ₁ and i ₂ differ depending on the distances to the detection electrodes 4d. Therefore, the light receiving position x from the detection electrode 4d on the lead 6a side is x = L × from the currents i ₁ and i _2. It is calculated by i ₂ / (i ₁ + i ₂ ).

Here, L is the light receiving length of the optical position detecting element 4. Therefore, in the detection circuit 7 of FIG. 13, such currents i ₁ and i ₂ are applied to the voltage V by the current-voltage conversion circuits 7a and 7b, respectively.
₁ , V ₂ is converted, and (V ₁ + V ₂ ) is obtained by the adder circuit 7c. The comparison and integration circuit 7d passes through the light emitting circuit 7e so that the addition result (V ₁ + V ₂ ) becomes a predetermined constant value. The light emission intensity of the light source 3 is controlled, and the voltage V ₂ corresponding to one of the currents i ₂ is multiplied by a predetermined gain in the amplifier circuit 7f and output, so as to correspond to the light receiving position x of the light position detecting element 4,
A rotation angle output Vθ corresponding to the rotation angle θ of the rotary slit plate 2 is obtained.

Next, the conventional rotation angle detecting device disclosed in Japanese Patent Laid-Open No. 61-124821 is constructed as shown in FIG. In FIG. 15, 10 is a case, 11 is a bearing that rotatably supports the rotating shaft 12, and 1 is a bearing.
Reference numerals 3 denote rotating slit members that are supported at one end of the rotary shaft 12 and that rotate together with the rotary shaft 12. The rotating slit member 13 is configured to include a light transmitting body 14 and a light reflecting layer 15 that covers the light transmitting body 14.

The light reflection layer 15 of the rotary slit member 13 is
The rotating slit member is provided with a light source side slit 15a and a light receiving side slit 15b formed by removing a portion facing the light source 16 and a portion facing the light position detection element 17. The light source 16 is fixed to the case 10 and arranged on an extension line of the rotary shaft 12 on one end side. On the other hand, on the surface of the inner wall surface of the case 10 orthogonal to the rotating shaft 12 on the opposite side across the light source 16 and the rotating slit member 13, as shown in FIG. The optical position detection element 17 having the above is disposed and installed on the element substrate 18.

According to such an optical rotation angle detecting device, when light is projected from the light source 16 in the direction of the rotary shaft 12, a part of the light source side slit 15a of the rotary slit member 13 is projected.
The light is further incident on the light-transmitting body, is radially deflected by the first reflecting surface formed by the light-reflecting layer 15, is further transmitted through the light-transmitting body, and is also formed by the second light-reflecting layer 15. After being deflected in the direction of the optical position detecting element 17 by the reflection surface of, the light passing through the light receiving side slit 15b among the transmitted light enters the optical position detecting element 17. Therefore, the light incident position on the light position detecting element 17 changes with the rotation of the rotary slit member 13, and this is detected by the detection circuit 7 described in FIG. 12 to obtain the rotation angle output Vθ of the rotary shaft 12.

[0013]

However, in the above-mentioned conventional optical rotation angle detecting device, since the slit optical system is used in the rotation angle detecting portion, there are the following problems. That is, in the slit optical system shown in FIG. 13, the rotary slit 2 of the projection light from the light source 3 is used.
Since only the light passing through the intersection area of a and the fixed slit 5a is made incident on the light position detection element 4, the light flux utilization efficiency of the light source 3 is extremely low, and therefore the illuminance at the light position detection element 4 is low. Becomes low and the current signals i ₁ , i ₂
Was very small.

As a result, the dark current component due to the temperature change of the light position detecting element 4 cannot be ignored, the S / N ratio of position detection is very bad, and conversely, if the radiant intensity of the light source 3 is increased to increase the illuminance. There is a problem that the life of the light source 3 becomes short. Further, since the change in the rotation angle is detected by the light receiving position in the radial direction of the optical position detecting element 4, if the accuracy is increased without making the slits fine, the detection distance cannot but be extended in the radial direction. There was also a problem that the diameter would be large.

Further, the slit optical system in the conventional optical rotation angle detecting device shown in FIG. 15 has a better luminous flux utilization rate than the slit optical system of the device shown in FIG. At the same time, the spot diameter at the light receiving portion of the light position detecting element 17 becomes considerably larger than that at the light receiving side slit 15b as indicated by reference numeral 19 in FIG. 16 due to the presence of obliquely transmitted light passing through the light receiving side slit 15b. There is also a problem that the light receiving length of the position detection element 17 cannot be effectively used, and it is not suitable for measurement when the detection angle range is narrow or conversely when the detection angle range is close to 2π.

The object of the present invention is to solve the problems in the conventional optical rotation angle detecting device, and it is a small and long device capable of accurately detecting the rotation angle regardless of the size of the angle detection range. It is to provide an optical rotation angle of life and a detection device.

[0017]

The optical rotation angle detecting device of the present invention comprises a light source, an optical position detecting element formed in an annular shape around the optical axis of the light source, and one end of which is directed to the light source. Therefore, the optical fiber is arranged on the optical axis and has the other end directed to the optical position detecting element and an optical fiber having the other end movably supported along the optical position detecting element in conjunction with a rotation axis. It is configured to include a light means and a light collecting means arranged on one or both of one end side and the other end side of the light guide means.

[0018]

According to the optical rotation angle detecting device of the present invention, the light emitted from the light source enters the inside from one end of the light guide means formed of an optical fiber. The other end of the light guide means made of this optical fiber moves along the annular optical position detection element while being directed to the light receiving surface along with the rotation of the rotating shaft, and the light of the light source is moved to the movement stop position at the other end. The light is projected onto the light-receiving surface of the optical position detecting element which faces it. At that time, the light collecting means arranged on one or both of the one end side or the other end side of the light guiding means collects the light from the light source, the light emitted from the other end of the light guiding means, or both the light. To form spot light.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical rotation angle detecting device of the present invention will be described in more detail with reference to the embodiments shown in the drawings. FIG. 1 shows an optical rotation angle detection device 20 according to a first embodiment of the present invention. The optical rotation angle detection device 20 of this embodiment includes a rotation shaft 23 rotatably supported by a bearing 22 provided on a wall of a case 21. A detection circuit board 24 is attached to the inner wall surface of the case 21 facing the end of the rotary shaft 23.

On the detection circuit board 24 on the rotation center axis of the rotation shaft 23, a light source (eg, LED) is arranged so that the optical axis coincides with the rotation center axis and emits light toward the end of the rotation shaft 23. ) 25 is installed. An annular element support substrate 26 is provided on a circle centered on the light source 25 on the detection circuit board 24.
An optical position detecting element 27 is provided on the position 6.

The optical position detecting element 27 has basically the same configuration as that shown in FIG. 14 except that it has an annular shape, and has a width of about 1 to 2 mm on the bias electrode 27c.
The photoelectric conversion layer 27a is provided to some extent, and the transparent electrode 2 is provided on the surface thereof.
It is formed by polymerizing 7b. Detection electrodes 27d are attached to both ends of the circular transparent electrode 27b, and the electrodes 27d and the bias electrode 27c are connected to the conventional detection circuit 7 shown in FIG. 13 by leads 6a, 6b, 6c. There is. As such a light position detecting element 27, one in which the photoelectric conversion layer 27a is made of amorphous silicon is suitable for inexpensively manufacturing an element having such an annular light receiving portion. In this case, the LED as the light source 25 receives light. From the viewpoint of sensitivity and luminous efficiency, it is preferable to use green or red visible light.

A rotating member 28 connected to the end of the rotating shaft 23 is arranged in the case 21, and the rotating member 28 is u.
It supports an optical fiber 29 bent in a V shape (in this embodiment, an example using a multimode optical fiber is shown). A concave portion 30 having a size into which the light source 25 is inserted is formed on a surface of the rotating member 28 facing the light source on the central axis of rotation, and a conical reflective concentrator 31 is formed on the inner wall of the concave portion 30. The reflective concentrator 31 is formed by finishing the surface of a conical hole formed on the inner wall of the recess of the rotating member 28 to a mirror surface by plating or vapor deposition.

The light incident end face 2 which is one end of the optical fiber 29
9a is positioned in the condensing part of the reflector 31 so as to be substantially perpendicular to the optical axis of the light source 25, and the light emitting end face 29b at the other end is supported at a position facing the optical position detecting element 27 in close proximity. Has been done. Such an optical fiber 29 is formed by coating the periphery of the core 29c with a glad 29d. The optical fiber 29 can be inexpensively formed by using a plastic fiber formed of optical plastic, and can be bent with a small diameter.

According to the optical rotation angle detecting device 20 of the first embodiment having the above structure, the LE which is the light source 25 is used.
The light projected from D is reflected and condensed by the reflective condenser 31, and the condensed light enters the core 29c from the light incident end surface 29a of the optical fiber 29 supported by the rotating member 28. Light incident on the optical fiber 29 passes through the core 29c, changes its direction by 180 ° due to the u-shaped bending of the optical fiber 29, and exits from the light emitting end surface 29d at the other end, and the light receiving portion of the optical position detecting element 27. The spot light 32 is focused on the upper side.

The spot light 32 moves on the light receiving portion of the optical position detecting element 27 by the rotation of the rotating member 28 associated with the rotary shaft 23. Therefore, the light incident position on the light receiving portion of the light position detecting element 27 becomes equal to the rotation angle of the rotating member 28, that is, the rotating shaft 23, and its current outputs i ₁ and i ₂ are transmitted to the detecting circuit 7 on the detecting circuit board 24. The rotation angle output Vθ corresponding to the light incident position x is output.

In the first embodiment, the spot light diameter on the light position detecting element 27 is the core 29 of the optical fiber 29.
It is determined by the diameter of c and the numerical aperture NA at the end face of the optical fiber. Therefore, by bringing the end face of the optical fiber on the optical position detecting element side close to the optical position detecting element 27, the optical fiber 2
Since the spot light whose core diameter is substantially the same as that of 9 is projected on the optical position detecting element 27, most of the emitted light from the light source 25 is condensed on the optical position detecting element 27 as a minute spot.

Therefore, the luminous flux utilization efficiency is extremely high, and the illuminance on the light position detecting element 27 can be made sufficiently large without increasing the drive current of the LED which is the light source 25. Error can be ignored and the S / N ratio of position detection is improved. As a result, the position detection accuracy can be improved and the life of the LED can be extended,
Position can be detected with high accuracy over a long period of time.

Further, in the first embodiment, no optical lens component is used, the cost can be reduced, and the spot light diameter is determined by the core diameter and the numerical aperture of the optical fiber 29. It can be made minute by selecting a small number. That is, in such an embodiment, the spot light diameter on the light position detecting element 27 can be made minute and the end to end of the light receiving portion can be effectively detected, so that even if the detection angle range is narrow, it is possible to accurately detect and the maximum detection angle. The range can be set to approximately 2π, and even the light position detecting element of the light receiving portion having a small diameter can be detected accurately, so that the device can be made small and small in diameter.

Next, FIG. 3, FIG. 4 and FIG. 5 show the condensing means which can be used in the optical rotation angle detecting device 20 in the above-mentioned embodiment and condense the emitted light from the light source 25 into the optical fiber. Another example is shown. The light collecting means shown in FIG. 3 has a microball lens 33 arranged on an LED chip which is a light source, and collects light from the light source 25 on an incident end face of the optical fiber light.

The light condensing means shown in FIG. 4 has a condensing lens 34 arranged on the LED which is the light source 25. In this example, the condenser lens 34 is separated from the LED and the optical fiber 2
Although it is arranged between one end of 9 and LED, a lensed LED in which a condenser lens is built in the LED may be used. Also, FIG.
The condensing means shown in (1) uses a spherical optical fiber in which the tip of the core of the optical fiber 29 is melted into a spherical shape, and the spherical portion 35 acts as a lens to condense light. By using such an optical system, the emitted light from the light source can be more efficiently condensed in the optical fiber 29, and the light utilization efficiency is improved.

FIG. 6 shows an optical rotation angle detecting device 40 according to the second embodiment of the present invention. In FIG. 6 showing the second embodiment, the same or corresponding parts as those of the optical rotation angle detecting device 20 of the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals and described. Is omitted. This second
In the optical rotation angle detection device 40 of this embodiment, the spiral optical position detection element 41 whose radius changes according to the rotation angle is provided on the ring-shaped element support substrate 26.

As an optical system, an optical system for converging the strip-shaped focused light 42 at the light emitting side end portion, for example, as shown in FIGS. 7 and 8, the light emitting side end portion has cores 43a aligned in a radial direction. The optical fiber 43 arranged in the above is used. The 2π rotation angle can be detected by using the optical position detecting element 41 and the optical fiber 43. 6 and 7, reference numeral 41a is a photoelectric conversion layer, 41b is a transparent electrode, 41c is a bias electrode, 41d is a detection electrode, and 4d.
3b shows the clad, respectively.

FIG. 9 shows an optical rotation angle detecting device 50 according to the third embodiment of the present invention. The optical rotation angle detecting device 50 of the third embodiment is the first embodiment shown in FIG.
Unlike the embodiment of FIG.
It is arranged on the inner wall of the case 21 on the side of the rotating shaft facing the. The optical fiber 29 is also supported by the rotating member 28 in an S-shape accordingly. Except for these points, it is the same as the optical rotation angle detection device of the first embodiment.

According to the optical type rotation angle detecting device 50 of the third embodiment, the light source 25 and the optical position detecting element 27 are arranged so as to face each other, so that the optical fiber 29 can be made short and the circle can be reduced. When the annular optical position detection element 27 is formed to have a small diameter and is brought close to the rotary shaft 23, the radius of curvature of the bent portion of the optical fiber 29 becomes small, the optical system resolution is increased, and the optical position can be detected accurately and the device can be used. It can be made smaller.

Further, FIGS. 10, 11 and 12 show the position of the radiated light from the optical fiber 29 which can be used in the optical rotation angle detecting devices 20 and 50 in the first and third embodiments. A light collecting means for collecting light on the sensing element 27 is shown. FIG. 10 shows an example in which a condenser lens 36 is arranged between the light emitting end face of the optical fiber 29 and the light position detecting element 27. FIG. 11 shows an example in which a spherical optical fiber having a spherical core is formed at the light emitting end of the optical fiber 29, and the spherical portion 37 acts as a lens to emit light emitted from the optical fiber 29. The light is focused on the position detection element 27.

Finally, FIG. 12 shows an example in which a microball lens 38 is arranged on the light emitting end surface of the optical fiber 29. Instead of the micro ball lens 38, a micro drum lens may be used. In addition, these light collecting means 36, 3
7, 38 rotate together with the radiation end of the optical fiber 29.
If the radiated light from the optical fiber 29 is condensed on the optical position detecting element 27 with such a configuration, the optical fiber diameter, that is, the core diameter can be increased to improve the light utilization efficiency and detect the optical position. The spot light 32 condensed on the element 27 can be made smaller.

In FIGS. 10 to 12 showing such a light collecting means, the reflection type light collector 31 described in the first embodiment is arranged at the light incident end of the optical fiber 29. Instead of such a condenser 31, a condenser as shown in FIGS. 3 to 5 may be used, or the optical fiber 2
It is possible to obtain a predetermined effect without specially installing a light condensing unit at the light incident end of 9. Further, as the condensing means provided at the light incident end of the optical fiber, the reflection type concentrator 31 shown in FIG. 1 and various condensing means shown in FIGS. 3 to 5 are illustrated. It goes without saying that the light means can be used for the second embodiment shown in FIG. 6 as well as the light collecting means arranged at the optical fiber light emitting end shown in FIGS. 10 to 12.

In each of the above-mentioned embodiments, the light source 25 is L
The ED and the optical position detecting element 27 are separately provided in the detection circuit board 2
Although the LED and the optical position detecting element 27 may be simultaneously formed on a supporting substrate such as glass, the LED may be formed by processing a part of the surface of the detecting circuit board 24. The light position detection element 27 may be formed on the detection substrate. Further, the optical system including the first condensing unit and the second condensing unit can be configured by combining various lenses, reflecting mirrors, and the like other than those shown in the drawings, and the optical fiber can also have various shapes.

[0039]

As described above, according to the optical rotation angle detecting device of the present invention, the light guide means for guiding light from the light source to the annular optical position detecting element is an optical fiber, and its light incident end. Alternatively, by providing the light condensing means at either one or both of the light emitting ends, the rotation angle can be accurately detected regardless of the size of the angle detection range, and a small-sized and long-life rotation angle detection device can be obtained. ..

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an optical rotation angle detection device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing an optical position detecting element in the optical rotation angle detecting device shown in FIG.

FIG. 3 is a structural explanatory view showing a first condensing unit that condenses and makes the light from the light source enter the optical fiber in the optical rotation angle detection device of the present invention.

FIG. 4 is a structural explanatory view showing another first condensing unit that condenses and makes the light from the light source incident on the optical fiber in the optical rotation angle detection device of the present invention.

FIG. 5 is a structural explanatory view showing still another first condensing means for condensing and making the light from the light source enter the optical fiber in the optical rotation angle detecting device of the present invention.

FIG. 6 is a plan view showing an optical position detection element in an optical rotation angle detection device according to a second embodiment of the present invention.

FIG. 7 is a front view of an optical fiber used in the optical rotation angle detection device shown in FIG.

FIG. 8 is a side view of the optical fiber shown in FIG.

FIG. 9 is a sectional view schematically showing an optical rotation angle detection device according to a third embodiment of the present invention.

FIG. 10 is a structural explanatory view showing a second condensing means installed at a light emitting end of an optical fiber in the optical rotation angle detecting device of the present invention.

FIG. 11 is a structural explanatory view showing another second light condensing means installed at the light emitting end of the optical fiber in the optical rotation angle detecting device of the present invention.

FIG. 12 is a structural explanatory view showing still another second light converging means installed at the light emitting end of the optical fiber in the optical rotation angle detecting device of the present invention.

FIG. 13 is a structural explanatory view schematically showing a conventional optical rotation angle detection device.

FIG. 14 is a partial cross-sectional view showing a structure of an optical position detecting element in a conventional optical rotation angle detecting device.

FIG. 15 is a structural explanatory view schematically showing another conventional optical rotation angle detection device.

16 is a plan view showing an optical position detection element and a rotation stopper member in the conventional optical rotation angle detection device shown in FIG.

[Explanation of symbols]

 20 Optical Rotation Angle Detection Device 21 Case 23 Rotation Axis 24 Detection Circuit Board 25 Light Source 27 Optical Position Detection Element 28 Rotating Member 29 Optical Fiber 31 Reflective Condenser 36 Condenser Lens

Claims (1)

[Claims] 1. A light source, an optical position detecting element formed in an annular shape around the optical axis of the light source, one end arranged on the optical axis so as to be directed to the light source, and the other end being the optical position. A light guide means, which is directed to the detection element and is formed of an optical fiber whose other end is movably supported along the optical position detection element in conjunction with a rotation axis, and one end side or the other end side of the light guide means. An optical rotation angle detection device including a light condensing unit disposed on either one or both of the above.