JPH0238891B2 - ROOTARIIENKOODANOSAKUSEIHOHOOYOBISORENYORISAKUSEISARETA ROOTARIIENKOODA - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a rotary encoder in which strong optical energy such as a laser is applied via an optical fiber, and a rotary encoder produced by the method.

[Conventional technology]

Conventionally, as means for detecting this type of angular position information, there has been an optical disk in which a plurality of micro holograms are arranged in a line along the circumference [Japanese Patent Application Laid-open No. 105156/1983], and a laser beam has also been used. A device that records information by evaporating an optically opaque layer at the location hit by a laser beam.
No. 40479], and a photoelectric device in which a light emitting element and a light receiving element are disposed opposite to a concave part of a base body, and information about a member passing through the concave part can be obtained [Utility Model No. 51-
No. 40272] is known.

[Problem to be solved by the invention]

By the way, in conventional rotary encoders, the rotary disk after the slit is made is attached to the shaft, so the difference in the center of the slit from the rotation center of the shaft, that is, the eccentricity at the time of installation, causes a detection error.
Especially in rotary encoders with a large number of slits that require high resolution, the amount of eccentricity causes a detection error.

In order to reduce the influence of eccentricity, the center diameter of the slit must be made large.
The outer diameter of the encoder becomes larger.

It takes time to install and adjust the rotating disk.

It is very difficult to reduce the amount of eccentricity to zero.

There were other drawbacks. Furthermore, when attaching a rotary encoder directly to a motor shaft, current rotary encoders have integrated electronic components such as light emitting and receiving elements and waveform shaping circuits, which limits the operating temperature range and requires measures against motor noise. There was a drawback that it did not work.

To give an example of these, when manufacturing a high-precision rotary encoder such as a 6000-slit rotary encoder, in order to attach the rotary disk to the shaft, the eccentricity must be 5 micrometers (μm) or less using a microscope and jigs. The drawback was that it took time to install and adjust as it had to be installed while adjusting it to the correct value.

In addition, when the number of slits is 6000 or more, the mounting accuracy is approaching the limit if the same method used for mounting with a small number of slits is used, and it is necessary to use new technical means to exceed that limit. It was hot.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new method for creating a rotary encoder that overcomes the drawbacks of the conventional example as described above, and furthermore, it is an object of the present invention to provide a method for creating a new rotary encoder that overcomes the drawbacks of the conventional example. The purpose is to provide a rotary encoder that eliminates all problems.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention includes a transparent disk attached to a motor shaft, and a rotating disk provided with a light-shielding thin film that can be dissolved and evaporated by laser light on at least one surface of the transparent disk, and arranged so as to be freely rotatable. (b) forming an optical fiber support body by molding the straight part including the straight part with a plastic material; cutting the fiber support together with the optical fiber to form a groove; inserting a part of the rotating disk into the groove formed by cutting the fiber support; and irradiating the laser beam from the optical fiber; A method for manufacturing a rotary encoder, characterized in that slits are created in the rotating disk, and the creation of one or more slits by irradiation with laser light is performed while sequentially rotating the rotating disk, and , an optical fiber having an optical fiber support formed by forming a straight part in the middle part and molding the straight part including the straight part with a plastic material; On the other hand, the fiber support is cut out along with the optical fiber to have a predetermined width that is perpendicular and slightly larger than the thickness of the rotary disc of the encoder, and as the part of the rotary disc rotates, the optical fiber is constantly cut off. The rotary circle is a transparent disk having a groove formed to allow passage through the part and is fixedly disposed on a motor shaft of a motor that drives a load, and a light-shielding thin film that can be dissolved and evaporated by laser light is provided on at least one surface of the rotating circle. A plate is inserted into the groove, and one or more slits are created by irradiating the laser beam from one end of the optical fiber introduced from the outside of the optical fiber support while sequentially rotating the rotating disk. a light emitting element that emits a laser beam and a light receiving element that receives the laser beam through the slit; This is a rotary encoder characterized by comprising:

[Effect]

The present invention is a method for producing the above-mentioned rotary encoder and a rotary encoder formed by the method, so an optical fiber support is formed by molding with a plastic material, and the optical fiber support is perpendicular to the straight part and has a predetermined width. Since the optical fiber support is cut out along with the optical fiber to form a groove, the optical axes of the optical fibers on the emitting side and the receiving side can be aligned, making it possible to create a high-precision rotary encoder with extremely low optical loss. , Also, such a high-precision rotary encoder can be obtained.

〔Example〕

FIG. 1 is a block diagram of a circuit configuration representing one embodiment of the present invention, showing an apparatus for creating a slit for a rotary encoder using an optical fiber and a laser beam.

1 is a bismuth thin film, 2 is a glass disk, 3 is a shaft, 4 is a hub, 5 is a fixed side detection part, 6,
Reference numeral 6' indicates an optical fiber, 7 indicates a laser device, and 8 indicates a mounting motor, that is, an original motor for operating as a rotary encoder, and in the case of a single rotary encoder, a bracket.

9 is a coupling, 10 is a control circuit, 11 is a reference angle signal generator (angle standard), 12 is a drive circuit, 13 is a drive motor that rotates the shaft 3 for processing, 14 is a drive signal, and 15 is an angle signal ,
16 is a laser control signal.

The glass disk 2 has a bismuth thin film deposited with bismuth but without slits, and a drive motor 13 is rotated via the drive circuit in response to a drive signal 14 from a control circuit 10, and its rotation angle is controlled by an angle signal 15. It is fed back to the circuit 10, and this rotation angle is controlled in a closed loop.

Following the controlled rotation angle via the coupling 9, the glass disk 2 is rotated.

On the other hand, the laser control signal 16 from the control circuit 10
is applied to the laser device 7 in such a way that it is related to the angle signal 15.

In this way, the optical laser generated from the laser device 7 passes through the optical fiber 6 and spots the bismuth thin film 1 deposited on the glass disk 2 at the fixed detection unit 5 with the energy of the optical laser. Create a slit by melting and evaporating it. In this case, the optical fiber 6' is not required.

Here, the bismuth-deposited glass disk 2
In addition to metal thin films formed by vapor deposition, it may be any material whose physical properties change with light energy and this change can be detected by some means, such as by exposing it to light and then developing it by applying heat. Any film such as this may be used.

By the way, the optical fibers 6, 6' and the fixed side detection section 5 are manufactured as follows.

That is, a straight part is formed in the middle part of the optical fiber, and the straight part is molded with a plastic material to constitute the optical fiber support [solid-side detection part 5]. A groove is formed by cutting out the fiber support [fixed side detection section 5] along with the optical fibers 6, 6' with a predetermined width, and a part of the rotating disk [glass disk 2] is cut out from the fiber support [solid side detection section]. 5] is cut and inserted into the groove formed, and slits are created by irradiating laser light from the optical fibers 6, 6'.The creation of one or more slits by the irradiation of this laser light is achieved by inserting the rotating disc [glass disk 2] is performed while sequentially rotating.

The state of the fiber support body [fixed side detection unit 5] together with the formed optical fibers 6, 6' constitutes a rotary encoder as it is, and a laser beam is applied to one of the optical fibers 6, 6'. A light emitting element is disposed on the other side and a light receiving element is disposed on the other side, and one or more optical fibers 6, 6' are disposed in parallel as required.

FIG. 2 is an explanatory diagram of the operation of the apparatus shown in FIG. 1.

For example, when creating 6000 slits, the drive motor 13 rotates (360°/2×6000).

In the meantime, the optical laser generated from the laser generator 7 passes through the optical fiber 6 and passes through the glass disk 2.
A slit 20 is formed by melting and evaporating the bismuth thin film 1 on top.

Do this operation every other time (360°/2×6000) In this case, a 6000-slit disk will be completed.

However, the number of optical fibers 6 is not limited to one; if a plurality of thin optical fibers 6 are bundled together as shown in FIGS. 3 and 4, the shape and dimensions of the slit 20 can be changed arbitrarily. can.

FIG. 5 is a schematic diagram of the configuration of a rotary encoder according to the present invention.

This represents the case where the rotary encoder produced in the embodiment of FIG. 1 is used as a rotation angle detector.

That is, as shown in FIG.
A low-energy light that does not melt and evaporate the bismuth thin film 1 is irradiated from below, and the optical fiber 6 used when manufacturing the slit 20 is used as it is.
The control circuit 21 converts the strength of the transmitted light from the slit portion into an electric signal, and 17 is a light emitting element;
Reference numeral 8 indicates a light receiving element, and reference numeral 19 indicates an output signal.Since the motor 8 can be controlled at a location distant from the motor 8 through the optical fiber 6, problems such as temperature noise are eliminated.

FIG. 6 is a block diagram of another embodiment of the invention.

This is a method for creating slits 20 using an optical laser, in which the drive motor 13 is
It is rotated by a constant speed rotation drive means such as the Lockcd Loop system.

When the pulse has a duty cycle of 50%, the pulse signal 27 with the frequency shown by the laser control pulse frequency F [hertz/Hz] = rotational speed of the drive motor 13 (rps) × number of slits 20 is used. It is sufficient to generate the pulse frequency from the laser control pulse frequency generator 26 and add it as a control signal to the laser device 28. 22 is a PLL control circuit, 23 is a PLL detector,
24 is its detection signal, and 25 is a motor rotation speed signal.

This embodiment is a slit making means that does not use the reference angle signal generating device 11, and if the rotation is performed at high speed, the slit can be made in a short time.

7 to 11 are explanatory views of optical fiber fixing means as another embodiment of the present invention.

When using the optical fiber 6, if the optical axes of the light-emitting side optical fiber and the light-receiving side optical fiber do not match, a light output loss will occur.

Therefore, the following can be considered as a method for forming the fixed side detection (sensor) section 5 whose optical axes coincide.

One or more optical fibers 6 as shown in FIG.
The middle part is molded with a plastic material such as resin, and the eighth
As shown in Figure 9, an air hole 29 perpendicular to the straight part of the optical fiber and narrow enough to allow the disc to rotate therein is cut between the molds together with the fiber, and the cut surfaces 30 By polishing and 31, it is possible to create a detection unit 5 with zero deviation of the optical axis, and the optical axes of the human-powered light 32 and the output light 33 match. This is precisely the feature of the present invention.

FIGS. 10 and 11 are cross-sectional diagrams showing different shapes of the optical fiber 6 in the embodiment of the present invention.

Fig. 10 shows a triangular cross-section made up of optical fibers 6 with different diameters, and Fig. 11 shows one in which spacers 36 and 37 are inserted between the optical fibers 6 and molded. It becomes possible to increase the density and arrange the optical fibers 6 with accurate dimensions.

〔Effect of the invention〕

Thus, according to the present invention, (a) an optical fiber support is formed by molding with a plastic material, and a groove is formed by cutting the optical fiber support together with the optical fiber perpendicular to the straight portion and having a predetermined width; This makes it possible to match the optical axes of the optical fibers on the emitting side and the receiving side, making it possible to create a highly accurate rotary encoder with extremely low optical loss. Since a slit is created, detection errors due to eccentricity that occur when mounting the disk are eliminated.

(b) No adjustment time is required to make the amount of eccentricity zero.

(c) Since there is no eccentricity, the center diameter of the slit in the rotating disk can be made small, making it possible to manufacture a rotary encoder smaller than conventional ones.

(d) Since the same optical fiber used when making the slit is used, there is no need to integrate the emitting/light receiving elements and circuit components, such as the control circuit, with the encoder, so there is no effect on the elements due to the temperature rise of the motor. From this point of view as well, it can be made smaller and there is no interference from noise generated by the motor.

(e) By bundling the optical fibers in a triangular cross section, the amount of light can be increased, it is easy to process, and the S/N is low.
This has the effect of improving accuracy by averaging errors and improving accuracy.

In particular, since the present invention uses a rotating disk with slits created by this method, the optical axes of the light emitting side and the light receiving side can be aligned quite easily.
It is possible to obtain a highly accurate rotary encoder with particularly low optical loss.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the circuit configuration of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the device shown in FIG. 1,
3 and 4 are diagrams of the formation of an optical fiber in one embodiment of the present invention, FIG. 5 is a schematic diagram of the configuration of a rotary encoder in one embodiment of the present invention, and FIG. 6 is a diagram of another embodiment of the present invention. The block diagrams showing the circuit configuration and FIGS. 7 to 11 are explanatory diagrams of the optical fiber fixing means in another embodiment of the present invention. 1...Bismuth thin film, 2...Glass disk,
3... Shaft, 4... Hub, 5... Fixed side detection unit, 6, 6'... Optical fiber, 7, 28... Laser device, 8... Mounting motor, 9... Coupling, 10... Control Circuit, 11... Reference angle signal generator (angle standard), 12... Drive circuit, 13
... Drive motor, 14 ... Drive signal, 15 ... Angle signal, 16 ... Laser control signal, 17 ... Light emitting element, 18 ... Light receiving element, 19 ... Output signal, 2
0...Slit, 21...Control circuit, 22...
PLL (Phase Locked Loop) control circuit, 23...
...PLL detector, 24...detection signal, 25...
Motor rotation speed signal, 26...Pulse frequency generator for laser control, 27...Pulse signal, 29...
Sky = 30, 31...Cut and polished surface, 3
2...Input light, 33...Output light, 36, 37...
Spacer.

Claims (1)

[Scope of Claims] 1. A rotary disk is provided with a light-shielding thin film that can be dissolved and evaporated by laser light on at least one surface of a transparent disk attached to a motor shaft, and is arranged so as to be freely rotatable. A straight part is formed in the middle part of the fiber, and the straight part is molded with a plastic material to constitute an optical fiber support, and the straight part is perpendicular to the straight part and has a predetermined width. cutting out the fiber support to form a groove; inserting a portion of the rotary disk into the groove formed by cutting out the fiber support; and irradiating the laser beam from the optical fiber to cut the slit into the rotation circle; 1. A method for producing a rotary encoder, comprising: forming one or more slits on a plate, and forming one or more slits by irradiating the laser beam while sequentially rotating the rotating disk. 2. An optical fiber having an optical fiber support formed by forming a straight part in the middle part and molding the straight part including the straight part with a plastic material, wherein the optical fiber support has a straight part contained in the optical fiber support. On the other hand, the fiber support is cut out along with the optical fiber to have a predetermined width that is perpendicular and slightly larger than the thickness of the rotary disc of the encoder, and as the part of the rotary disc rotates, the optical fiber is constantly cut away. The rotary disk is provided with a light-shielding thin film that can be dissolved and evaporated by laser light on at least one surface of a transparent disk that is fixedly disposed on a motor shaft of a motor that drives a load. The one prepared by inserting the rotating disk into the groove and sequentially rotating the rotating disk while irradiating the laser beam from one end of the optical fiber introduced from the outside of the optical fiber support. The above slit is provided, and a light emitting element that emits a laser beam and a light receiving element that receives the laser beam through the slit are provided at one end of the optical fiber and the other end of the optical fiber that passes through the fiber support. A rotary encoder characterized by: