JPS6312916A - Absolute angle measuring instrument - Google Patents

Abstract

PURPOSE:To measure the movement quantity of a body to be measured with simple structure by rotating a cylindrical lens which varies the refractive angle of incident light according to rotation by a driving means coupled with the rotary shaft whose angle is to be measured, and detecting the angle of rotation from its outgoing light. CONSTITUTION:The hollow homogeneous cylindrical lens 1 which is so worked that the internal circle and external circle shift in center axis from each other is fitted to a holder 2. This holder 2 is coupled with the rotary shaft 3 whose angle is to be measured through a coupling 4. Consequently, the lens 1 rotates as the rotary shaft 3 rotates. Then, a prism 5 is fixed in the lens 1 independently of the lens 1, and consequently laser light outputted by a laser oscillator 6 is refracted by 90 deg., made incident on the lens 1 from its internal circle, and projected from its external circle. The output laser light is photodetected by the photodetector 7 composed of photodetecting elements 71-7n. Therefore, the photodetection position 7n of the photodetector 7 corresponding to the angle of rotation of the rotary shaft 3 and therefore lens 1 one to one is easily detected and the absolute value of the angle of rotation of the body to be measured is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an absolute angle measuring device for measuring mechanical movement or displacement, particularly rotational angular displacement.

[Conventional technology]

Conventional devices for measuring rotational angular displacement include synchro devices and shaft encoders. The output of a synchronizer is an analog quantity, and the output of a shaft encoder is a digital quantity.

There are two types of shaft encoders: an optical type that uses a code plate of a rotating disk and a light receiving element, and a magnetic type that uses a magnetic gear or a magnetic recording rotating drum and a magnetoresistive element.

A typical optical shaft encoder will be described with reference to FIG. In this optical encoder, light outputted from a light source 30 such as an incandescent lamp or a light emitting diode is converted into parallel light by a collimator lens 31, and the collimator lens 31 converts light into parallel light.
The light is manually applied to the light receiving elements 35a and 35b through the second slit 33 and the fixed slit 34.

The collimator lens 31 is for reducing the spread of light due to diffraction when the light passes through the rotating disk 32, and the fixed slit 34 allows the light that has passed through the slit 33 of the rotating disk 32 to pass through the two light receiving elements 35a.

When receiving light with 35b, shift the timing of receiving light (
As shown in the figure, this is for shifting the phase of the output signal waveform by, for example, 90 degrees. With the above configuration, when the rotating disk 32 rotates, the two light receiving elements 35a,
The output waveform from 35b is transferred to waveform shaping circuits 36a and 36b.
The waveform is shaped and converted into a digital signal, thereby making it possible to detect the rotation angle and rotation direction of the rotating disk 32.

[Problem that the invention seeks to solve]

The above-mentioned optical shaft encoder is called an incremental shaft encoder and converts the rotation angle of a rotating disk or human shaft into the number of output pulses (digital amount) to detect an increase or decrease in the amount of movement (amount of rotation). In other words, although relative positions can be measured, absolute positions cannot be measured.

Furthermore, as an optical shaft encoder for measuring the absolute position of the amount of movement, that is, the angle of rotation, there is an absolute shaft encoder that uses a code plate with a complicated configuration. This encoder detects the position by converting the rotational angular position of the human-powered shaft into a code such as pure binary or binary coded decimal. However, since this absolute shaft encoder performs complicated code conversion, the configuration itself becomes extremely complicated and therefore expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a ground angle measuring device capable of measuring an absolute position of a movement amount, such as a rotation angle, with a simple configuration.

[Means for solving problems]

The absolute angle measuring device of the present invention includes a cylindrical lens whose refraction angle of incident light changes as it rotates, a driving means that is connected to a rotating shaft to be measured and rotates the cylindrical lens, and a cylindrical lens that receives light emitted from the cylindrical lens and rotates. The present invention is characterized in that it includes means for detecting an angle, and the rotation angle is measured in absolute value.

In a preferred embodiment of the present invention, the cylindrical lens is a homogeneous hollow cylindrical lens whose inner and outer circles are eccentric, and light such as a laser is made incident from inside the hollow cylindrical lens.

Further, light such as a laser is made to enter from outside the homogeneous cylindrical lens.

Furthermore, the cylindrical lens is made a non-uniform lens to improve the resolution of angle detection.

The invention will be explained with reference to the drawings.

FIG. 1 shows a schematic configuration of the absolute angle measuring device of the present invention. In the angle measuring device of the present invention, a hollow homogeneous cylindrical lens 1, which is machined so that the central axes of the inner and outer circles are shifted from each other, is attached to a holder 2. The holder 2 is connected via a coupling 4 to a rotating shaft 3 whose angle is to be measured. As a result, when the angle-measuring rotating shaft 3 rotates, the hollow cylindrical lens 1 also rotates. A prism 5 is fixed inside the hollow cylindrical lens 1 independently of the hollow cylindrical lens 1, so that the prism 5 cannot rotate even if the hollow cylindrical lens 1 rotates, so that the output from the laser oscillator 6 is The LED light is bent by 90 degrees so that it enters the hollow cylindrical lens 1 from its inner circle and exits from the outer circle at a refraction angle of θ. The output laser beam has multiple C
Light receiving element 7, such as CD, ---7. The light is received by a light receiver 7 consisting of the following. Therefore, when the hollow cylindrical lens 1 rotates, the zero refraction angle θ of the laser beam changes, and therefore the light receiving position of the light receiver changes.

[For production]

When the angle-measuring rotation shaft 3 rotates, the hollow cylindrical lens 1 rotates via the coupling 4 and holder 2. Therefore, the laser beam from the laser oscillator 6 is transmitted through the prism 5 at 90°
° It is bent and enters the hollow cylindrical lens 1, and the light is emitted at a refraction angle of θ to the light receiving element of the light receiver 7. , ---7,, is received. Therefore, it is possible to easily detect the light-receiving position of the light-receiving element 7° of the light receiver 7, which corresponds one-to-one to the rotation angle of the angle-measuring rotation axis 3, and thus the hollow cylindrical lens l.
This allows the rotation angle of the object to be measured to be measured in absolute value.

〔Example〕

Hollow cylindrical lens 1, holder 2, prism 5 shown in Fig. 1
, the detailed structure of the laser oscillator 6'J6 and the light receiver 7 is shown in FIG. A homogeneous cylindrical lens 1 processed into a hollow shape with the center axes of the outer circle and inner circle being shifted from each other is placed in the first holder 12 and the second holder 13 so that each center axis coincides with the center axis of the outer circle of the hollow cylindrical lens 1. Install it as shown. The first holder 12 and the second holder 13 have a first bearing 14 and a second bearing 14, respectively.
The bearing 15 allows the outer cylinder 16 to rotate freely. Further, the prism 5 is attached to the third holder 19 together with the laser oscillator 6 in such a positional relationship that the prism 5 receives the laser beam output from the laser oscillator 6 and is bent by 90 degrees. This third holder 19 is attached to a holder receiver 20, and the holder receiver 20 is attached to the first cover 21, and the laser oscillator 6
The optical axis of the hollow cylindrical lens 1 is aligned with the central axis of the outer circle of the hollow cylindrical lens 1. A light receiver 7 consisting of a plurality of light receiving elements 7° such as a CCD is attached to the outer cylinder 16 using a spacer 23.
Install via. The mounting position of the receiver 7 is shown in Figure 2 (B
), (C), and (D), at the refraction angle θ that changes with the rotation of the hollow cylindrical lens 1, the position where the refracted light within the range of the minimum angle -θsin and the maximum angle +θtaax can be received. do. Further, a second cover 24 is attached to the outer cylinder 16 on the opposite side of the first cover 21. In FIG. 2, when the first holder 12 rotates, the hollow cylindrical lens 1 attached thereto also rotates.

Assuming that the hollow cylindrical lens 1 is initially in the position shown in FIG. 3(a), the laser light emitted from the prism 5 enters the hollow cylindrical lens 1 from the inner circle as shown in the figure, and is refracted from the outer circle. Angle θ. It emits light at an angle of Furthermore, in this case, CCD
It is assumed that the laser beam is received at the position of the light-receiving element 76 in the light receiver 7 .

Further, from this initial position (a), the hollow cylindrical lens 1 moves to the positions (b)-(C)-(d)-(
e) - (f) - (g) and return to the initial position (a) after one rotation.
shall return to. In this case, the light receiving position of the light receiver 7 changes from the position of the first light receiving element 76 to the light receiving element 5 → 4 → 3 as the refraction angle changes from θ1 - θ2 → θ3 - θ, → θ5.
→The position changes from 9 to 8, and when it returns to the initial position (a), the light is received again at the position of the light receiving element 76. Therefore, the light receiving position at the light receiving element can be detected as an absolute position.

In the manner described above, the rotation angle of the hollow cylindrical lens 1, that is, the first holder 12, can be detected in absolute position. Therefore, by connecting the first holder 12 and the rotational shaft to be measured, the rotation angle of the rotational shaft to be measured can be detected as an absolute value.

Next, a second embodiment of the absolute angle measuring device of the present invention shown in FIG. 2 will be explained with reference to FIGS. 4(A) and 4(B).

In this example, the cylindrical lens 1' is not hollow but is a solid homogeneous cylindrical lens. The cylindrical lens 1' is attached to the holders 12' at a position where its central axis is offset from the rotational axes of the first and second holders 12' and 13'.

Attach to 13'. First and second nelda 12', 13
' is rotatably attached to the outer cylinder 16' by first and second bearings 14' and 15'. In addition, in this example, the laser oscillator 6' is attached to the outer cylinder by the mounting base 25 at a position where its tip axis is offset from the center axis of the cylindrical lens 1'.
Attach to 6'. A light receiver 7 consisting of a light receiving element 7 such as a CCD is attached to the outer cylinder 16' using a mounting spacer 23. The mounting position of the light receiver 7 is as shown in FIGS. 4(B) and 5 at the minimum angle θ71. ．． and maximum angle θ□
The position is such that it can receive refracted light within a range of 8. The rest of the configuration is the same as that shown in the first embodiment, so a description thereof will be omitted.

The operation of the second embodiment will be explained with reference to FIG.

In FIG. 4, when the first holder 12' rotates, the cylindrical lens 1' also rotates. Cylindrical lens 1' is initially box 5TEA
Assuming that the position is in (a), the laser beam output from the laser oscillator 6' enters the cylindrical lens 1' as shown in the figure, and the refraction angle is θ. The light is emitted from the cylindrical lens 1' at an angle of . The emitted laser light is received by the light receiver 7 at the position of the light receiving element 71 thereof. First and second holder 12
Since the rotation centers of ' and 13' and the center of the cylindrical lens 1' are misaligned, (a)-(b)-(C)-(
d) - (e) - (f) - (a) (7) As the first and second holders 12' and 13' rotate in order, the refraction angle of the laser beam emitted from the cylindrical lens 1' also changes to θ.

→ θ, → θ2 → θ3 → θ, → θ, → θ1, and accordingly, the position of the light receiving element 7h of the light receiver 7 also changes from 1 → 2 →
Changes from 3 → 4 → 5 → 8 → l. Therefore, by detecting the light receiving position of the light receiving element 7°, the first holder 12
', therefore, the rotation angle of the object can be detected in absolute position.

The present invention is not limited to the examples described above, and various modifications can be made.

For example, the hollow cylindrical lens 1 shown in FIG. 2 and the cylindrical lens 1' shown in FIG. 4 can be made into inhomogeneous lenses such as selfoc lenses.

In this case, since the range of the refraction angle θ of the laser beam emitted from the inhomogeneous cylindrical lens is further expanded, the light receiver 7
The number of light receiving elements 7° can be further increased, and therefore the resolution of angle detection can be further improved. For example, the difference in refraction angle in Figures 3(a) and (b) (θ.-01)
becomes large, and as a result, the resolution when detecting the rotation angle of the cylindrical lens 1 is significantly improved.

〔Effect of the invention〕

According to the absolute angle measuring device of the present invention configured as described above, the absolute angle of the rotation axis can be detected and measured with a simple configuration without requiring a code plate and code conversion device with a complicated configuration. An inexpensive absolute angle measuring device can be provided.

[Brief Description of the Drawings] Figure 1 is a schematic diagram showing the basic configuration of the absolute angle measuring device of the present invention, Figure 2 (^) is a vertical cross-sectional view showing the detailed configuration, and Figure 2 (B) , (C) and (D) are cross-sectional views thereof, Figures 3 (a) to (areas are explanatory diagrams showing the operation of the device of the present invention shown in Figure 2, and Figure 4 (A) is a cross-sectional view of the present invention. A vertical sectional view showing another example of the absolute angle measuring device, FIG. 4(B) is a cross sectional view thereof, and FIGS. 5(a) to (f) show the operation of the device of the present invention shown in FIG. 4. Explanatory drawing, FIG. 6 is a perspective view showing the configuration of a conventional optical shaft encoder. 1... Hollow cylindrical lens 1'... Cylindrical lens 2,
12.13.12", 13', 19...Holder 3.
...Rotating shaft 4...Coupling 5...
Prism 6.6'... Laser oscillator 7... Light receiver 7I~7. ,... Light receiving element 14, 15.14', 15'... Bearing 1
6...Outer cylinder 20...Holder receiver 21.2
4-1. Cover 23.25...Mounting spacer Patent applicant: Olympus Optical Industry Co., Ltd. Kisara: / Figure 1 (A) (B) 1. Cylindrical lens 2, holder 3, rotation axis 5, prism 6, Laser oscillator 7, light receiver Fig. 2 (A) (B) (C) (D) Fig. 3 (a) (b) (c) (d) Fig. 4 (A) CB) Fig. 5 (a) ( b) (e) (f) (c) (d) (g) R' Procedural amendment (voluntary) September 18, 1985

Claims (1)

[Claims] 1. A cylindrical lens whose refraction angle of incident light changes as it rotates, a driving means connected to the angle-measuring rotation axis to rotate the cylindrical lens, and a means for detecting the rotation angle by receiving light emitted from the cylindrical lens. An absolute angle measuring device characterized in that it measures rotation angles in absolute values.