JPH06265370A - Optical rotation-angle detection apparatus - Google Patents

Abstract

PURPOSE:To obtain an apparatus wherein it can detect a rotation angle with high accuracy, its double axis can be formed easily, it is made small-sized and its light source can be made long-life by a method wherein the distance between an optical diffusion face formed on one face of a rotary member and a reference face perpendicular to a shaft is constituted so as to be different according to the rotation angle. CONSTITUTION:An optical diffusion face 16 is formed spirally in one part on the surface of a rotary member 15 in such a way that its height from a reference face perpendicular to a shaft 1 is different according to a rotation angle. The diffusion face 16 is irradiated with a beam of light from a light source 3, a beam of reflected light is condensed by an optical position-detection element 21, output currents from electrodes 21a, 21b are converted into voltages by a detection circuit 17, the voltages are added, the light-emitting amount of the light source 3 is controlled in such a way that an added voltage becomes a prescribed voltage, and an angle detected value is found. Thereby, the rotation angle of an object to be measured can be detected with high accuracy irrespective of the magnitude of an angle detection range, an optical system 19 can be formed to be compact near the shaft 1, and a double axis can be constituted easily. In addition, since the diffusion face 16 can be irradiated directly with the light source 3, the light-emitting amount is small and the life of the light source can be made long.

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 for detecting the rotation angle of an object in a non-contact manner, and more particularly to an optical rotation angle detection type optical rotation angle using, for example, an optical position detection element as a light receiving element. The present invention relates to a detection device.

[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 for detecting the rotation angle of the object while being in electrical contact with the object using a variable resistor. Radiation from a rotating object instead of an angle detector
Alternatively, a non-contact type optical system in which light reflected and transmitted by a rotating object is received by an optical position detection element equipped with a resistance layer and the rotation angle of the rotating object is detected according to the light receiving position of this optical position detection element. A rotation angle detection device is used. As such an optical rotation angle detecting device, for example, FIGS.
The one shown in 7 has been proposed. FIG. 16 is a block diagram showing a conventional optical rotation angle detecting device disclosed in Japanese Patent Laid-Open No. 61-246620, and FIG. 17A is a conventional optical rotation angle detecting device disclosed in Japanese Patent Laid-Open No. 61-124821. 17B is a configuration diagram of the angle detection device, and FIG. 17B is a top view of the optical position detection unit of the conventional optical rotation angle detection device shown in FIG. 17A.

First, referring to FIG. 16, Japanese Patent Laid-Open No. 61-24
A conventional optical rotation angle detection device disclosed in Japanese Patent No. 6620 will be described. In the figure, 1 is a rotary shaft connected to a rotating object, which is not shown, and 2 is a rotary slit plate which is inserted into and attached to the rotary shaft 1 and which rotates with the rotary shaft 1. 2a is a rotary slit plate. The rotary slit plate 2 is formed in a spiral shape on the slit plate 2.
A spiral slit whose radius changes according to the rotation of
Is a light source, 4 is a fixed slit plate arranged within the range of the optical axis of the light source 3 and parallel to the rotary slit plate 2,
4a is a spiral slit 2a formed on the rotary slit plate 2.
The fixed slits 5 formed on the fixed slit plate 4 so as to intersect with the light are emitted from the light source 3 and supplied with the light supplied through the spiral slit 2a of the rotary slit plate 2 and the fixed slit 4a of the fixed slit plate 4. In order to receive light, the light position detecting elements 6 and 8 arranged so that the light receiving axis thereof is in the radial direction of the rotary slit plate 2, 6 and 8 are connected to the respective electrodes of the light position detecting element 5, and the light position detecting element 5 Is connected to the bias voltage applying electrode of the optical position detecting element 5, and a power supply for supplying a bias voltage from a power supply circuit (not shown) to the optical position detecting element 5. It is a terminal.

Next, the operation will be described. When the light is emitted from the light source 3 in the direction of the rotary slit plate 2, the emitted light is projected onto the projection range S on the rotary slit plate 2, and of the projected light, the spiral slit 2a of the rotary slit plate 2 is projected. Only light passing through the intersection of the fixed slit 4a of the fixed slit plate 4 and the fixed slit plate 4 is incident on the light receiving surface of the optical position detecting element 5. Therefore, when the rotary slit plate 2 rotates together with the rotary shaft 1,
The intersecting range of the spiral slit 2a of the rotary slit plate 2 and the fixed slit 4a of the fixed slit plate 4 is the rotary slit plate 2
On the optical position detecting element 5 because the light receiving position on the optical position detecting element 5 moves in the radial direction of the rotating slit plate 2 and changes according to the rotation angle of the rotating slit plate 2. The rotation angle of the rotary shaft 1 is detected by detecting the output current ratio of the output currents from the output terminals 6 and 8 connected to the both end electrodes of the light position detection element can do. Therefore, it is possible to detect the rotation angle of the measured object to which the rotation shaft 1 is connected.

Next, referring to FIG. 17, Japanese Patent Laid-Open No. 61-12
A conventional optical rotation angle detection device disclosed in Japanese Patent No. 4821 will be described. 17, parts corresponding to those in FIG. 16 are designated by the same reference numerals, and detailed description thereof will be omitted. In the figure, 9 is a case whose shape is cylindrical as shown in FIG. 17B, 10 is a rotary bearing for supporting the rotary shaft 1, 11 is the inside of the case 9, and the rotary bearing of this case 9 is shown. An annular element support substrate attached to the 10 side, an annular optical support 12 attached to the inside of the case 9, and an annular element support substrate 10 attached to the inside of the case 9 in the same manner as the element support substrate 10. It is a position detection element. Further, numeral 13 directs its light emission direction to the inside of the case 9, and makes light from the light source 3 attached to the hole of the case 9 incident on the optical position detection element 12 so that the optical axis coincides with the axis of the rotating shaft 1. It is a rotary slit member for making it. The rotary slit member 13 includes a light-transmitting body 13a having a light-reflecting layer 13d formed therein, and the light-transmitting body 13a includes a light source side slit 13b for passing light from the light source 3 and a light source side. Slit 13b
A first reflection surface 13c for reflecting the light incident from the second reflection surface 13c, a second reflection surface 13e for reflecting the light reflected by the first reflection surface 13c, and a light position detection element for the light reflected by the second reflection surface 13e. Light-receiving side slit 13 for making light incident on 12
f is formed.

Next, the operation will be described. When light is emitted from the light source 3, a part of the emitted light enters the light transmitting body 13a from the light source side slit 13b of the rotary slit member 13, and the light is transmitted as shown by a dashed line in FIG. The light is reflected by the first reflecting surface 13c formed inside the body 13a, passes through the light transmitting body 13a, reaches the second reflecting surface 13e, is reflected by the second reflecting surface 13e, and is further transmitted by the light transmitting body 13a. After passing through the light receiving side slit 13f, the light enters the light receiving surface of the optical position detecting element 12. in this case,
As the rotary slit member 13 rotates, the optical position detecting element 12
Since the projection range S (spot) of the light with respect to changes,
The light receiving position on the light position detecting element 12 is determined by the light position detecting element 1
The rotation angle of the rotary shaft 1 can be detected by detecting the output current ratio of the output currents from the output terminals 6 and 8 connected to the two end electrodes of No. 2 by a detection system (not shown). Therefore, it is possible to detect the rotation angle of the measured object to which the rotation shaft 1 is connected.

[0007]

Since the conventional optical rotation angle detecting device is constructed as described above, it has the following problems. That is, in the optical rotation angle detection device described with reference to FIG. 16, the rotation angle change is detected at a one-to-one correspondence with the slit position change at the light receiving position in the radial direction of the light position detection element 5. Therefore, if it is attempted to improve the detection accuracy without making the spiral slit 2a and the fixed slit 4a small, the detection distance has to be extended in the radial direction, the diameter of the device becomes large, and moreover, the light source 3 passes through the slit. Since the predetermined spot diameter is obtained, it is necessary to increase the light emission amount of the light source 3, and there is a problem that the life of the light source 3 is shortened accordingly.

In the optical rotation angle detecting device described with reference to FIG. 17, the diameter of the spot on the light receiving surface of the light position detecting element 12, that is, the diameter of the light projection range S (spot) shown in FIG. 17B. However, since the diameter of the obliquely transmitted light that passes through the light-receiving side slit 13f is larger than the diameter of the light-receiving side slit 13f, the light-receiving length of the optical position detection element 12 cannot be effectively used, and the detection angle range is reduced. It is not suitable for measurement when the detection angle range is narrow or close to 2π, and there is a problem that the two-axis configuration cannot be adopted because the light source 3 is arranged coaxially with the rotating shaft 1. It was

The present invention has been made in order to solve such a problem, and it is possible to detect the rotation angle of the object to be measured with high accuracy regardless of the size of the angle detection range, and it is possible to easily realize the double axis. It is an object of the present invention to provide an optical rotation angle detection device that is compact, and that can extend the life of a light source.

[0010]

An optical rotation angle detecting device according to a first aspect of the present invention includes a rotary shaft that is attached to a part to be measured or a part of the rotary shaft, and is integrally attached to the rotary shaft. A rotating member that rotates is provided, and at least a part of at least one of an upper surface and a bottom surface of the rotating member is an optical diffusion surface, and a distance between the optical diffusion surface and a reference plane perpendicular to the rotation axis is a rotation angle. Further, the light source for irradiating the optical diffusing surface of the rotating member with light, and the reflected light from the optical diffusing surface of the rotating member at a distance from the reference surface of the rotating member. A condensing optical system for condensing at a corresponding incident position, and a light position detecting element arranged at a substantially condensing position of this condensing optical system, based on the light incident position on the light position detecting element, The rotation angle of the object to be measured is detected. It is obtained by the.

An optical rotation angle detecting device according to a second aspect of the present invention is a rotary shaft attached to or part of an object to be measured, and a rotary member attached to the rotary shaft and rotating integrally. And a part of at least one of the upper surface and the bottom surface of the rotating member is an optical diffusing surface, and the distance H between the optical diffusing surface and the reference surface perpendicular to the rotation axis is relative to the rotation angle θ. H = 1 / (a × θ + b)
(Where a and b are predetermined constants), the optical diffusing surface is formed. Further, a light source for irradiating the optical diffusing surface of the rotating member with light and a light source from the optical diffusing surface of the rotating member. A condensing optical system that condenses the reflected light at an incident position corresponding to a distance from the reference surface of the rotating member, and an optical position detection element disposed at a substantially condensing position of the condensing optical system,
The rotation angle of the object to be measured is detected based on the light incident position on the light position detecting element.

[0012]

According to the first aspect of the invention, the light is reflected from the optical diffusing surface of the rotating member at a substantially condensing position of the condensing optical system for condensing it at an incident position corresponding to the distance from the reference surface of the rotating member. The rotation angle of the measured object is detected based on the light incident position on the arranged light position detecting element. As a result, a rotation angle can be accurately detected regardless of the size of the angle detection range, a biaxial configuration is easy, and the light source has a long life.

According to the second aspect of the invention, the distance H from the reference plane perpendicular to the rotation axis is relative to the rotation angle θ,
H = 1 / (a × θ + b) (where a and b are predetermined constants) The incident position of reflected light from the optical diffusion surface formed on the rotating member according to the distance from the reference surface of the rotating member The light is condensed by the condensing optical system, and the rotation angle of the object to be measured is detected based on the light incident position on the light position detecting element arranged at the substantially condensing position of the condensing optical system. As a result, a linear output proportional to the rotation angle can be obtained, and the rotation angle can be accurately detected regardless of the size of the angle detection range, the two-axis configuration is easy, and the light source is small and inexpensive. A device with a long life can be obtained.

[0014]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.
In the figure, parts corresponding to those in FIGS. 16 and 17 are designated by the same reference numerals, and detailed description thereof will be omitted. Reference numeral 15 is a rotating member that is locked to the object to be measured (not shown), or is fixed to the rotary shaft 1 forming a part of the object to be measured or integrally formed with the rotary shaft 1 so as to rotate together with the rotary shaft 1. . Reference numeral 16 denotes an optical diffusing surface formed in a spiral shape on a part of the upper surface of the rotating member 15 such that the height from the lower surface perpendicular to the rotation axis 1 varies depending on the rotation angle. The height of the rotating member 15 from the lower surface is formed so as to be different depending on the rotation angle in the angle range of 360 degrees.

Reference numeral 17 supplies a drive current to the light source 3 via the input terminal 18 of the optical system 19 to cause the light source 3 to emit light, and an output current supplied via the output terminals 22 and 23 of the optical system 19. Is a detection circuit for detecting the rotation angle of the object to be measured based on the above, and outputting the detection result via the output terminal 24. The optical system 19 includes, for example, a light source 3 such as an LED whose emission optical axis is substantially parallel to the rotation axis 1 and which has a narrow directivity angle.
And a condenser lens 20 for condensing the light emitted from the light source 3 and reflected by the optical diffusion surface 16, and an optical system 19 for receiving the light condensed by the condenser lens 20.
Of the electrodes 21a and 2 on both ends thereof.
1b is formed by the optical position detecting elements 21 respectively formed.

Here, for example, a semiconductor one-dimensional optical position detecting element is used as the optical position detecting element 21. When a semiconductor one-dimensional optical position detecting element is used as the optical position detecting element 21,
The LED used as the light source 3 is, for example, about 800 to 900 n.
A near infrared LED having a wavelength of m is advantageous in terms of sensitivity. However, when the periphery of the rotating member 15 is sealed, the amorphous one-dimensional light position detecting element and the visible light LE are
The use of D is cost effective. Further, when using the semiconductor one-dimensional light position detection element in a natural light atmosphere, the semiconductor one-dimensional light position detection element has sensitivity in the visible light region,
It is necessary to provide a visible light cut filter in front of the detection element. In the following example, the optical position detecting element 21
As an example, it is assumed that a uniform resistance layer is formed on the photodiode and electrodes are provided at both ends thereof.

FIG. 2 is a sectional view taken along line AA of the optical rotation angle detecting device shown in FIG. In this figure, FIG.
6 and parts corresponding to those in FIG. 17 are designated by the same reference numerals, and detailed description thereof will be omitted. Reference numeral 25 denotes an annular substrate for mounting the detection circuit 17 (see FIG. 4) described later and the optical system 19 shown in FIG. 1, and the substrate 25 is attached to the upper surface of the inside of the case 9. Reference numeral 26 is a disc spring, and the disc spring 26 is attached between the upper portion of the rotary member 15 and the rotary bearing 10 on one side. The attached disc spring 26 acts to press the rotary member 15 against the rotary bearing 10 by its biasing force, so that rattling in the axial direction can be eliminated.

The optical system 19 is mounted on the substrate 25 as described above. That is, as shown in the drawing, the light source 3 is mounted on the left side of the substrate 25 so that the light emission direction is downward in the drawing, and the light source 3 is mounted so as to surround the light source 3 mounted on the substrate 25.
A diaphragm member 27 for narrowing the light emitted from is mounted, the light position detecting element 21 is mounted on the right side of the substrate 25, and the light receiving surface of the light position detecting element 21 is at a position where light can be substantially focused. As described above, the diaphragm lens 27 and the support member 28 support the condenser lens 20. Here, the rotating member 1
5 is made of, for example, a plastic material having a small coefficient of thermal expansion, and is manufactured by integrally performing injection molding with the rotary shaft 1 inserted in the injection molding portion of the injection molding machine. The optical diffusion surface 16 is formed by roughening the upper surface of the rotating member 15. FIG. 3 is a top view of the optical system shown in FIGS. As shown in FIG. 3, the major axis direction of the optical system 19 connecting the light source 3 and the optical position detection element 21 is arranged so as to coincide with the radial direction of rotation of the rotary member 15.

FIG. 4 is a diagram showing the configuration of the optical system and the electrical configuration of the detection circuit 17 of the optical rotation angle detecting device shown in FIG. 4, parts corresponding to those in FIGS. 1 to 3 are designated by the same reference numerals, and detailed description thereof will be omitted. In the figure, reference numerals 29 and 34 denote electrodes 21a and 21b on one side and the other side of the optical position detecting element 21 and input terminals 22 and 2 respectively.
A current / voltage conversion (I / V) circuit for converting the output currents respectively supplied via 3 into voltages V1 and V2, 30 adds the output voltages V1 and V2 from these current / voltage conversion circuits 29 and 34 It is an adder circuit. Reference numeral 31 connects the power supply terminal 32 to which the comparison voltage Vs for comparison is supplied to the non-inverting input terminal (+), and connects the inverting input terminal (-) and the output terminal with a capacitor 33 for integration, and performs addition. A comparison and integration circuit for comparing the added output from the circuit 30 with the comparison voltage Vs, 35 is connected to a power supply terminal 36 to which the gain voltage K is supplied to one of its input terminals, and this gain voltage K is input to the other input. A division circuit for dividing by the output voltage V2 from the current / voltage conversion circuit 34 supplied to the terminal, 37 has a power supply terminal 38 to which the bias voltage Vb is supplied connected to one of its input terminals, and a division circuit 35. Is a summing circuit for adding the K / V2 supplied to the other input terminal and the bias voltage Vb to obtain the output voltage Vout as the angle detection value.

Next, the operation will be described. When radiated light with a narrow directivity angle is projected from the light source 3 through the diaphragm member 27 onto the projection area S (see FIG. 1) on the optical diffusion surface 16 on the upper surface of the rotating member 15, the projection area S of the optical diffusion surface 16 is projected. Of the diffuse reflected light, the diffuse reflected light having a solid angle facing the condenser lens 20 is condensed by the condenser lens 20 on the light receiving surface on the optical position detection element 21. The light flux incident on the light position detection element 21 is converted into a photocurrent by a photoelectric conversion layer including a photodiode. This photocurrent shunts through the resistance layer at a shunt ratio corresponding to the incident position of the light flux, and the electrodes 21a and 21b formed at both ends thereof
Are output as currents I1 and I2 (see FIG. 4), respectively, and the currents I1 and I2 are input to the current / voltage conversion circuit 2 via the input terminals 22 and 23 of the detection circuit 17, respectively.
9 and 34 respectively. At this time, the light beam incident position X (see FIG. 4) on the light position detecting element 21 is equal to the current I
From 1 and I2, it can be obtained as follows.

X = L × I2 / (I1 + I2) (1)

However, in the above equation (1), L is the light receiving length of the light position detecting element 21.

Further, as the rotary shaft 1 rotates, the rotary member 1
When 5 rotates, the distance H between the projection range S on the optical diffusion surface 16 on the upper surface of the rotating member 15 and the condenser lens 20 (see FIG. 4).
Changes according to the rotation angle θ of the rotating member 15, and the distance H
(Θ) can be calculated as follows based on the principle of triangulation.

H (θ) = f × B / X = f × B × (I1 × I2) / (L × I2) (2)

However, in the above equation (2), f is the focal length of the condenser lens 20, and B is the reference distance between the emission optical axis of the light source 3 and the optical axis of the condenser lens 20 (see FIG. 4).

Next, in the detection circuit 17, the detection currents I1 and I2 from the optical position detection element 21 are converted into voltages V1 and V2 by the current / voltage conversion circuits 29 and 34, respectively, and the voltage V1 obtained by the conversion is obtained. And V2 are added by the adder circuit 30 to become a voltage (V1 + V2), and the addition result of this adder circuit 30 is supplied to the comparison and integration circuit 31.
In the comparison and integration circuit 31, the light emission amount of the light source is controlled so that it becomes a predetermined constant voltage Vs. As a result, the numerator of the equation (2) is set to a constant value, K / V2 is obtained from the predetermined gain K in the division circuit 35 for the voltage V2 corresponding to one of the currents I2, and the addition circuit 37 determines the predetermined value. Bias voltage Vb is added, and this is output from the output terminal 24 as the addition result Vout, that is, the angle detection value. This addition result Vout can be expressed by the following equation.

Vout (θ) = (K / V2) + Vb (3)

FIG. 5 is an output characteristic diagram of the optical rotation angle detecting device described with reference to FIGS.
The output characteristics are shown with an angle θ (angle range of 360 degrees) on the out and x axes. From the expressions (2) and (3), the output voltage Vout is proportional to the distance. Since the spiral optical diffusion surface 16 of the rotating member 15 is formed so that the distance H is directly proportional to the rotation angle θ, the output voltage Vo is thereby obtained.
As shown in FIG. 5, ut is a very linear output proportional to the rotation angle θ of the rotary shaft 1.

As described above, in this embodiment, the light source 3 is provided on the optical diffusion surface 16 formed in a spiral shape on the upper surface of the rotating member 15.
From the optical diffusing surface 16 is condensed by the condenser lens 20 on the optical position detecting element 21, and the output current I1 from the electrodes 21a and 21b at both ends of the optical position detecting element 21 is I2 is a current / voltage conversion circuit 29 and 34
Are converted into voltages V1 and V2, respectively, and these two voltages V1 and V2 are added by the adder circuit 30. The light emission amount of the light source 3 is controlled so that the added output becomes a predetermined constant voltage Vs, and the current / current Since the gain K is divided by the output voltage V2 from the voltage conversion circuit 34 and a predetermined bias voltage Vb is added to the output to obtain the output voltage Vout, that is, the angle detection value, the rotation angle detection range. The rotation angle of the object to be measured can be detected with high accuracy regardless of the size of the optical axis, and the optical system 19 can rotate the rotary shaft 1 on one side of the rotary member 15.
Since it can be formed in a compact size in the vicinity, it is possible to easily realize a dual shaft and to make the device small (the rotating member 15 and the case 9 have a small diameter). Also, the light source 3
Can directly irradiate the optical diffusion surface 16 without interposing a slit, so that the amount of light emission can be reduced and the life can be extended.

Example 2. In the above embodiment, the light source 3
The case where the long axis direction of the optical system 19 connecting the optical position detecting element 21 and the optical position detection element 21 is arranged so as to coincide with the rotation radius direction of the rotating member 15 has been described (see FIG. 3), but as shown in FIG. The major axis direction of the optical system 19 may be arranged tangentially. In this case, the device can be made smaller (the rotating member 15 and the case 9 have a smaller diameter).

Example 3. FIG. 7 is a diagram showing a configuration of an optical system of an optical rotation angle detection device according to still another embodiment of the present invention and an electrical configuration of a detection circuit 17A. 7, parts corresponding to those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted. In the figure, reference numeral 40 is an amplifier circuit for applying a predetermined gain K. In this example, as shown in the figure, the output terminal of the current / voltage conversion circuit 34 is connected to the inverting input terminal (−) of the adder circuit 30 and the comparison and integration circuit 31, and the output terminal of the adder circuit 30 is amplified. It is connected to the input terminal of the adder circuit 37 via the circuit 40.

In this case, the comparison and integration circuit 31 controls the light emission amount of the light source 3 so that the voltage V2 corresponding to the one detection current I2 of the light position detecting element 21 becomes a predetermined constant voltage Vs, and the voltage V1 And V2 are added by the adder circuit 30 to obtain a voltage (V1 + V2), and this voltage (V1 + V
After a predetermined gain K is applied to 2) by the amplification circuit 40, a predetermined bias voltage Vb is added to this output by the addition circuit 37 to obtain the output voltage Vout. The output voltage Vout at this time can be expressed as follows.

Vout (θ) = K × (V1 + V2) + Vb (4)

Even when the optical rotation angle detecting device is constructed in this way, it is possible to obtain a linear output as described with reference to FIG. 5, and the division circuit 35 described with reference to FIG. 4 is not necessary. The circuit configuration can be simplified and the cost of the device can be reduced.

Example 4. FIG. 8 is a diagram showing the configuration of the optical system of the optical rotation angle detection device of yet another embodiment of the present invention and the electrical configuration of the detection circuit 17B. In this FIG. 8, parts corresponding to those in FIG. 4 and FIG.
Detailed description thereof will be omitted. In this example, the output terminal of the current / voltage conversion circuit 29 is connected to one input terminal of the addition circuit 30, the output terminal of the current / voltage conversion circuit 34 is connected to the other input terminal of the addition circuit 30, and The output terminal of the current / conversion circuit 34 is connected to the input terminal of the adder circuit 37 via the amplifier circuit 40.

In this case, the optical diffusion surface is adjusted so that the distance H between the optical diffusion surface 16 on the upper surface of the rotation member 15 and the condenser lens 20 has the characteristic shown in FIG. 9 with respect to the rotation angle θ of the rotation member 15. 16 are formed. This can be expressed as follows.

H = 1 / (aθ + b) (5)

Therefore, the light beam incident position X of the light position detecting element 21 with respect to the rotation angle θ of the rotating shaft 1 can be expressed by the following equation (2).

X = f × B × (aθ + b) (6)

That is, as is apparent from the equation (6), the light beam incident position X changes linearly with the rotation angle θ, so that the addition result (V1 + V2) becomes a predetermined constant voltage Vs in FIG. The light amount of the light source 3 is controlled by the comparison and integration circuit 31, and the voltage V corresponding to one detection current I2
After a predetermined gain is applied to 2 by the amplifier circuit 40, a predetermined bias voltage Vb is added by the adder circuit 37 to output the output voltage Vo.
Output as ut. This makes it possible to obtain a linear output proportional to the rotation angle θ, as in the case described with reference to FIG. Even when the optical rotation angle detecting device is configured in this way, it is possible to obtain a linear output as described in FIG. 5 and the division circuit 35 described in FIG. And the cost of the device can be reduced.

Example 5. FIG. 10 is a diagram showing an optical system of an optical rotation angle detecting device according to still another embodiment of the present invention, FIG.
1 is an output characteristic diagram of the optical system shown in FIG. This Figure 1
0, parts corresponding to those in FIGS. 1 to 9 are denoted by the same reference numerals, and detailed description thereof will be omitted. In this example, the upper surface of the cylindrical rotating member 45 is cut obliquely to form the optical diffusion surface 46. The distance H between the optical diffusion surface 46 and the optical system 19 becomes a 2π periodic function of the rotation angle θ, and the output Vout
Changes in a cycle of 360 degrees as shown in FIG. In this example, the optical diffusing surface 4 is adjusted so that the output period becomes 2π.
Although the case where 6 is formed is shown, by changing the shape of the upper surface of the rotating member 45, it is possible to obtain those having various cycles.

Example 6. FIG. 12 is a diagram showing a configuration of an optical system of an optical rotation angle detecting device according to still another embodiment of the present invention, and FIG. 13 is an output characteristic diagram of the optical system shown in FIG.
12, parts corresponding to those in FIGS. 1 to 11 are designated by the same reference numerals, and detailed description thereof will be omitted. In this example, spiral optical diffusion surfaces 48 and 49 having different rotation angle detection ranges are formed on the upper and lower surfaces of the rotating member 47, and the optical diffusion surfaces 48 and 49 are formed on the upper and lower surfaces of the rotating member 47, respectively. The optical systems 19a and 19 corresponding to
Use two b's. With this configuration,
When the outputs of the two optical systems 19a and 19b are ma and mb, the respective output characteristics are as shown in FIG. In this example, since it is possible to obtain two outputs having different sensitivities with respect to the rotation angle θ, an output characteristic having high sensitivity is used in an angular range where accuracy is required, and an output having low sensitivity is used in other regions. The usage such as using the property becomes possible. Although ma and mb are shown separately as the output Vout in FIG. 13, the addition result of the outputs ma and mb may be the actual output Vout.

Example 7. FIG. 14A is a diagram showing a configuration of an optical system of an optical rotation angle detecting device according to still another embodiment of the present invention, and FIG. 14B is a top view of the optical system shown in FIG. 14A.
14, parts corresponding to those in FIGS. 1 to 12 are designated by the same reference numerals, and detailed description thereof will be omitted. In this example, an area is radially divided on the upper surface of the rotating member 50 to form a spiral optical diffusion surface 5 having different rotation angle detection ranges.
0a and 50b are formed. Then, two condenser lenses 52 are provided corresponding to these two optical diffusion surfaces 50a and 50b.
And 53 (or a converging lens integrally molded), and an optical system 51 having two optical position detecting elements 53a and 53b. Then, the light from the light source 3 is divided into two optical diffusion surfaces 50a and 50b and irradiated, and the reflected light is condensed by the two condenser lenses 52 and 53 onto the two optical position detection elements 53a and 53b. The distance to each of the optical diffusion surfaces 50a and 50b is detected based on the light collection position.

With this configuration, when the outputs of the two optical position detecting elements 53a and 53b are ma and mb, their output characteristics are as shown in FIG. 13 as in the optical system shown in FIG. become. In this example, since it is possible to obtain two outputs having different sensitivities with respect to the rotation angle θ, an output characteristic having high sensitivity is used in an angular range where accuracy is required, and an output having low sensitivity is used in other regions. The usage such as using the property becomes possible. Further, since only one light source 3 is required, and if the condenser lenses 52 and 53 are integrally molded, it is not necessary to divide the substrate, so that only one optical system 51 is required. Can be reduced. In FIG. 13, the output Vo
Although ma and mb are shown separately as ut, the output m
The result of addition of a and mb may be used as the actual output Vout.

Example 8. FIG. 15 is a view showing the arrangement of the optical system of an optical rotation angle detector according to yet another embodiment of the present invention. 15, parts corresponding to those in FIGS. 1 to 14 are designated by the same reference numerals, and detailed description thereof will be omitted. In this example, the optical position detecting element 21 is provided on the left side of the substrate 57.
Is mounted, the light source 3 is mounted slightly downward to the right of the center, and a diaphragm member 59 for confining the light emitted from the light source 3 is mounted so as to surround the light source.
The condenser lens 20 is supported by the left portion of the support member 58 and the diaphragm member 59 so that the light can be substantially focused on the light receiving surface of the. A support member 60 is attached to the right end of the substrate 57, and a light receiving element (for example, a photodiode) 61 is attached to the support member 60 with its light receiving surface facing left. Here, the light receiving element 61 is provided on the right side of the diaphragm member 59.
A slit 59a for receiving light is formed.

On the other hand, an optical diffusion surface 55a whose distance H changes periodically with respect to the rotation angle is formed on the upper surface of the rotating member 55, and the light receiving element 61 is made to receive light at the upper end portion of its outer peripheral portion 55b. A slit 55c for forming is formed. In this case, the light emitted from the light source 3 is reflected by the optical diffusion surface 55a, and the reflected light is condensed by the condenser lens 20 on the optical position detecting element 21 to obtain the rotation angle θ and the light source 3
Of the light output from the slit 59a of the diaphragm member 59
Also, the reference angular position can be obtained by detecting the light passing through the slit 55c of the outer peripheral portion 55b of the rotating member 55 with the light receiving element 61.

Example 9. In the above eighth embodiment, the outer peripheral portion 55b
Although the description has been given of the case where the single slit 55c is used, the rotary encoder can be configured by providing the slits 55c at every predetermined angle, and various angle detection ranges shown in the above respective embodiments can be obtained. When combined with the optical diffusing surface that it has, it is possible to obtain a variety of rotation angle detection devices that can obtain both analog and digital rotation angle outputs.

Example 10. In each of the above embodiments, the case where a light source having a narrow directional angle characteristic is used has been described, but for example, if a parallel light source is used, the irradiation area on the optical diffusion surface does not change depending on the distance. There is an advantage that the change of the condensing diameter can be reduced and the angular resolution can be further improved.

Example 11. Further, in each of the above embodiments, the case where the optical diffusion surface is obtained by roughening the upper and lower surfaces of the rotating member has been described. For example, a seal or a sheet whose surface is an optical diffusion surface on the upper and lower surfaces of the rotating member. May be attached.

[0050]

As described above, according to the first aspect of the present invention, the rotary shaft that is attached to the object to be measured or is a part thereof, and the rotary member that is attached to the rotary shaft and rotates integrally. At least one of the top surface and the bottom surface of the rotating member is an optical diffusing surface, and the distance between the optical diffusing surface and the reference surface perpendicular to the rotation axis is different depending on the rotation angle. Further, a light source for irradiating the optical diffusing surface of the rotating member with light, and reflected light from the optical diffusing surface of the rotating member at an incident position corresponding to a distance from the reference surface of the rotating member. A light collecting optical system for collecting light and a light position detecting element arranged at a substantially light collecting position of the light collecting optical system are provided. Based on the light incident position on the light position detecting element, Since the rotation angle is detected, angle detection Can accurately detect the rotation angle regardless of the size of circumference, both axes configuration easier, and, in a small, light source there is an effect that it is possible to obtain a device of long lifetime.

According to the second aspect of the present invention, there is provided a rotating shaft attached to or part of the object to be measured, and a rotating member attached to the rotating shaft and rotating integrally. At least one of the top surface and the bottom surface of the member is an optical diffusing surface, and the distance H between the optical diffusing surface and the reference plane perpendicular to the rotation axis is H = 1 / (a × θ + b) (where a and b are predetermined constants), the optical diffusion surface is formed, and further, a light source for irradiating the optical diffusion surface of the rotating member with light and the optical diffusion of the rotating member. A condensing optical system for condensing the reflected light from the surface at an incident position corresponding to the distance from the reference surface of the rotating member, and an optical position detecting element arranged at a substantially condensing position of the condensing optical system. Based on the light incident position on the light position detecting element, Since the rotation angle of the DUT is detected, a linear output proportional to the rotation angle can be obtained, and the rotation angle can be detected accurately regardless of the size of the angle detection range. There is an effect that it is possible to obtain a device that is easy and small, has a long light source life, and is inexpensive.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an optical rotation angle detection device according to the present invention.

FIG. 2 is a sectional view taken along line AA of the optical rotation angle detection device according to the present invention shown in FIG.

FIG. 3 is a top view showing an optical system of an embodiment of the optical rotation angle detecting device according to the present invention.

FIG. 4 is a configuration diagram showing a configuration of an optical system and an electrical configuration of a detection circuit of an embodiment of an optical rotation angle detection device according to the present invention.

FIG. 5 is an output characteristic diagram for explaining one embodiment of the optical rotation angle detection device according to the present invention.

FIG. 6 is a top view showing an optical system of another embodiment of the optical rotation angle detecting device according to the present invention.

FIG. 7 is a configuration diagram showing a configuration of an optical system and an electrical configuration of a detection circuit of still another embodiment of the optical rotation angle detection device according to the present invention.

FIG. 8 is a configuration diagram showing a configuration of an optical system and an electrical configuration of a detection circuit of still another embodiment of the optical rotation angle detection device according to the present invention.

FIG. 9 is a diagram for explaining the relationship between the rotation angle θ and the distance between the diffuse reflection surface and the condensing optical system in still another embodiment of the optical rotation angle detection device according to the present invention.

FIG. 10 is a configuration diagram showing an optical system of still another embodiment of the optical rotation angle detecting device according to the present invention.

FIG. 11 is an output characteristic diagram for explaining yet another embodiment of the optical rotation angle detection device according to the present invention.

FIG. 12 is a configuration diagram showing an optical system of still another embodiment of the optical rotation angle detecting device according to the present invention.

FIG. 13 is an output characteristic diagram for explaining still another embodiment of the optical rotation angle detecting device according to the present invention.

14A and 14B are a structural view and a top view showing an optical system of still another embodiment of the optical rotation angle detecting device according to the present invention.

FIG. 15 is a configuration diagram showing an optical system of still another embodiment of the optical rotation angle detecting device according to the present invention.

FIG. 16 is a configuration diagram showing a conventional optical rotation angle detection device.

FIG. 17 is a configuration diagram showing a conventional optical rotation angle detection device.

[Explanation of symbols]

1 Rotation axis 3 Light source 15, 45, 47, 50, 55 Rotating member 16, 46, 48, 49, 50a, 50b, 55a Optical diffusion surface 17, 17A, 17B Detection circuit 20, 52, 53 Condensing lens 21, 22 , 53a, 53b Optical position detection elements 21a, 21b Electrodes

[Procedure amendment]

[Submission date] September 6, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

First, referring to FIG. 16, Japanese Patent Laid-Open No. 61-24
A conventional optical rotation angle detection device disclosed in Japanese Patent No. 6620 will be described. In the figure, 1 is a rotary shaft connected to a rotating object, which is not shown, and 2 is a rotary slit plate which is inserted into and attached to the rotary shaft 1 and which rotates with the rotary shaft 1. 2a is a rotary slit plate. The rotary slit plate 2 is formed in a spiral shape on the slit plate 2.
A spiral slit whose radius changes according to the rotation of
Is a light source, 4 is a fixed slit plate arranged within the range of the optical axis of the light source 3 and parallel to the rotary slit plate 2,
4a is a spiral slit 2 formed on the rotary slit plate 2.
Fixed slits 5 formed on the fixed slit plate 4 so as to intersect a are emitted from the light source 3 and
To receive light supplied through the spiral slit 2a and the fixed slit 4a of the fixed slit plate 4, the light receiving axis is arranged so that its light receiving axis is in the radial direction of the rotary slit plate 2, And 8 are the optical position detecting elements 5
An output terminal connected to each electrode of the optical position detecting element 5 for outputting a detection current of the optical position detecting element 5;
Is a power supply terminal connected to the bias voltage applying electrode of and supplying a bias voltage from a power supply circuit (not shown) to the optical position detecting element 5.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

Next, referring to FIG. 17, Japanese Patent Laid-Open No. 61-12
A conventional optical rotation angle detection device disclosed in Japanese Patent No. 4821 will be described. 17, parts corresponding to those in FIG. 16 are designated by the same reference numerals, and detailed description thereof will be omitted. In the figure, 9 is a case whose shape is cylindrical as shown in FIG. 17B, 10 is a rotary bearing for supporting the rotary shaft 1, 11 is the inside of the case 9, and the rotary bearing of this case 9 is shown. An annular element support substrate attached to the 10 side, an annular optical support 12 attached to the inside of the case 9, and an annular element support substrate 10 attached to the inside of the case 9 in the same manner as the element support substrate 10. It is a position detection element. Further, numeral 13 directs its light emission direction to the inside of the case 9, and makes light from the light source 3 attached to the hole of the case 9 incident on the optical position detection element 12 so that the optical axis coincides with the axis of the rotating shaft 1. It is a rotary slit member for making it. The rotary slit member 13 has its field
The light transmissive body 13a has a light reflection layer 13d formed on its surface . The translucent body 13a includes a light source side slit 13b and a light source side slit 13b for passing light from the light source 3.
A first reflection surface 13c for reflecting the light incident from the second reflection surface 13c, a second reflection surface 13e for reflecting the light reflected by the first reflection surface 13c, and a light position detection element for the light reflected by the second reflection surface 13e. Light-receiving side slit 13 for making light incident on 12
f is formed.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

According to the second aspect of the invention, the distance H from the reference plane perpendicular to the rotation axis is relative to the rotation angle θ,
H = 1 / (a × θ + b) (where a and b are predetermined constants) The incident position of reflected light from the optical diffusion surface formed on the rotating member according to the distance from the reference surface of the rotating member in is condensed by the condensing optical system, based on the light incident position on the optical position detecting element which is disposed substantially converging position of the converging optical system, that detect the rotation angle of the object to be measured. As a result, a linear output proportional to the rotation angle can be obtained, and the rotation angle can be accurately detected regardless of the size of the angle detection range, the two-axis configuration is easy, and the light source is small and inexpensive. A device with a long life can be obtained.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

FIG. 4 is a diagram showing the configuration of the optical system and the electrical configuration of the detection circuit 17 of the optical rotation angle detecting device shown in FIG. 4, parts corresponding to those in FIGS. 1 to 3 are designated by the same reference numerals, and detailed description thereof will be omitted. In the figure, reference numerals 29 and 34 denote electrodes 21a and 21b on one side and the other side of the optical position detecting element 21 and input terminals 22 and 2 respectively.
A current / voltage conversion (I / V) circuit for converting the output currents respectively supplied via 3 into voltages V1 and V2, 30 adds the output voltages V1 and V2 from these current / voltage conversion circuits 29 and 34 It is an adder circuit. 31 connects the power supply terminal 32 to compare the voltage Vs for comparison to the non-inverting input terminal (+) is supplied, an inverting input terminal (-) connected and between the output terminal by a capacitor 33 for integrating further
The inverting input terminal (-) is connected to the adder circuit 30 and a comparison and integration circuit for comparing the added output from the adder circuit 30 with the comparison voltage Vs, and 35 is a gain voltage K at one of its input terminals.
Is connected to the power supply terminal 36, and the gain voltage K
Is divided by the output voltage V2 from the current / voltage conversion circuit 34 supplied to the other input terminal, 37 is connected to the power supply terminal 38 to which the bias voltage Vb is supplied to one of the input terminals. , The result of division from the division circuit 35, that is, K / V2 supplied to the other input terminal and the bias voltage Vb are added, and the output voltage V as the angle detection value is obtained.
It is an adder circuit for obtaining out.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

H (θ) = f × B / X = f × B × (I1 + I2) / (L × I2) (2)

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

FIG. 5 is an output characteristic diagram of the optical rotation angle detecting device described with reference to FIGS.
The output characteristics are shown with an angle θ (angle range of 360 degrees) on the out and x axes. From the expressions (2) and (3), the output voltage Vout is proportional to the distance H. Since the spiral optical diffusion surface 16 of the rotating member 15 is formed so that the distance H is directly proportional to the rotation angle θ, the output voltage V
out is the rotation angle θ of the rotary shaft 1 as shown in FIG.
The output is very linear in proportion to.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

Even when the optical rotation angle detecting device is constructed in this way, from the above equations (2) and (4),
Since the output voltage Vout is also proportional to the distance H,
Similar to the embodiment of FIG. 5 , a linear output as shown in FIG. 5 can be obtained, and since the division circuit 35 described in FIG. 4 is not necessary, the circuit configuration can be simplified and the cost of the device can be reduced. You can

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

[Procedure Amendment 9]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 11

[Correction method] Change

[Correction content]

FIG. 11

[Procedure Amendment 10]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 16

[Correction method] Change

[Correction content]

FIG. 16

Claims (2)

[Claims] 1. A rotary shaft, which is attached to a part to be measured or is a part thereof, and a rotary member which is attached to the rotary shaft and rotates integrally with the rotary shaft. The rotary member has at least one of a top surface and a bottom surface thereof. A part of the optical diffusion surface is formed so that the distance between the optical diffusion surface and the reference plane perpendicular to the rotation axis is different depending on the rotation angle. And a condensing optical system for condensing the reflected light from the optical diffusion surface of the rotating member at an incident position corresponding to the distance from the reference surface of the rotating member, and the condensing optical system An optical system characterized by comprising a light position detecting element arranged at a substantially condensing position, and detecting a rotation angle of the measured object based on a light incident position on the light position detecting element. Rotation angle detection device. 2. A rotary shaft that is attached to or a part of a body to be measured, and a rotary member that is attached to the rotary shaft and rotates integrally. The rotary member has at least one of a top surface and a bottom surface. A part is an optical diffusion surface, and a distance H between the optical diffusion surface and a reference plane perpendicular to the rotation axis is relative to a rotation angle θ.
The optical diffusion surface is formed so that H = 1 / (a × θ + b) (where a and b are predetermined constants), and further, a light source that irradiates the optical diffusion surface of the rotating member with light, A condensing optical system that condenses the reflected light from the optical diffusion surface of the rotating member at an incident position corresponding to the distance from the reference surface of the rotating member, and is arranged at a substantially condensing position of this condensing optical system. And an optical position detecting element, and the rotation angle of the object to be measured is detected based on the light incident position on the optical position detecting element.