JPH09170935A - Optical rotary encoder and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical rotary encoder with stable output characteristic. SOLUTION: This rotary encoder is provided with a light emitting part 1, a collimator lens 2 which converts the light generated at the light emitting part 1 into parallel light, an optical disc 3 which makes the parallel light having passed the collimator lens 2 pass through or reflected, and a photodetecting element 4 which detects the light outputted through the optical disc 3. Between the collimator lens 2 and the optical disc 3, a filter 5 wherein pigment concentration becomes higher when going away from the center is provided with the optical axis between the light emitting part 1 and the photodetecting element 4 as the center.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical rotary encoder for detecting a rotational position, a rotational speed, etc. of a rotary shaft of an actuator and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, in an optical rotary encoder, for example, as shown in FIG. 4A, a light beam emitted from a light emitting section 1 is set to L1, and a collimating lens 2 sets a parallel light beam L2.
The optical disc 3 is passed through the optical disc 3, and the optical disc 3 is rotated. When the optical disc 3 is rotated, the rotational position and the rotational speed of the rotating shaft or the like on which the optical disc 3 is fixed are determined from the output signal of the light receiving device that receives the pulsed light. Is disclosed (for example, Japanese Laid-Open Patent Publication No. 63-1 / 1988).
44212).

[0003]

However, in the above-mentioned prior art, since the light rays from the light emitting portion are converted into parallel light rays by the collimator lens, the light density in the peripheral portion of the collimator lens increases, and as a result, as shown in FIG. As shown in (b),
A distribution in which the peripheral light amount far from the optical axis rises is shown.
If a processing error of the light emitting unit or lens is added to this, the light amount distribution of the light emitting unit will not be uniform with respect to the optical axis, and the light amount will vary in the irradiation range, which will adversely affect the output characteristics of the encoder. Therefore, a lot of man-hours are required,
There is a problem that the output signal processing circuit becomes complicated.
An object of the present invention is to provide an optical rotary encoder having a stable output characteristic by making the light amount distribution of light rays from a collimator lens uniform.

[0004]

In order to solve the above problems, the present invention provides a light emitting section, a collimator lens for converting light rays generated from the light emitting section into parallel light rays, and a parallel light ray passing through the collimator lens. In an optical rotary encoder including an optical disc that transmits or reflects light and a light receiving element that receives a light beam output through the optical disc, the light emitting unit and the light receiving element are provided between the collimator lens and the optical disc. A filter is provided in which the concentration of the dye increases with increasing distance from the center with the optical axis connected as the center. A method of manufacturing an optical rotary encoder, wherein a collimator lens is arranged on the front surface, an optical disc is arranged facing the collimator lens, and a light receiving element is arranged facing the optical disc, between the collimator lens and the optical disc.
A film coated with a photosensitive material that is sensitive to the light of the light emitting portion is arranged so that the center thereof coincides with the optical axis, and the light from the light emitting portion is irradiated to the film to expose it, and then the photosensitive material is developed.・ It is a method of fixing.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 is a configuration diagram showing an embodiment of the present invention. In the figure, 1 is a light emitting part, 2 is a collimator lens for converting the light beam L1 into a parallel light beam L2, 3 is an optical disk having slits at a predetermined pitch in the circumferential direction, and 4 is a parallel light beam L2 that has passed through the optical disk 3. It is a light receiving element that receives light. Reference numeral 5 denotes a filter provided between the light emitting unit 1 and the optical disc 3, and the concentration of the dye that suppresses the light intensity increases with distance from the center with the optical axis connecting the light receiving element 4 as the center. The manufacturing method of the filter 5 is as follows:
A film or glass plate coated with a photosensitive material that is exposed to the light is placed between the collimator lens 2 and the optical disc 3 with the center aligned with the optical axis, and the light beam L2 from the light emitting unit 1 is irradiated to expose the light. , Develop, and fix the dye 51. As a result, as shown in FIG. 2, the filter 5 is formed with a filter film in which the concentration of the dye 51 increases as the distance from the center coincident with the optical axis increases. As shown in the drawing, the density distribution shows the same change as the light quantity distribution of the light beam emitted from the collimator lens, and the transparency of the film automatically becomes worse in the peripheral portion far from the optical axis where the light quantity is large. Therefore, the light amount of the light ray L2 emitted from the light emitting unit 1 and transmitted through the collimator lens 2 passes through the filter 5 from the state of FIG.
As shown in (c), a uniform state is obtained around the optical axis.
It should be noted that in the above embodiment, the optical disc provided with the transmissive slit was described, but the present invention can also be applied to a reflective optical disc.

[0006]

As described above, according to the present invention, since the filter provided with the filter film in which the concentration of the dye increases as the distance from the center is increased, the filter is disposed between the collimator lens and the light receiving element. The light transmitted through the collimator lens has a uniform light amount distribution centered on the optical axis, and the complicated circuit that was conventionally required for electrical correction is simplified, the adjustment man-hours are reduced, and stable. There is an effect that an optical rotary encoder having output characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a plan view showing a filter according to an embodiment of the present invention.

FIG. 3A is a graph showing a light amount characteristic of a light ray after passing through a collimator lens, FIG. 3B is a graph showing a density characteristic of a filter, and FIG. 3C is a light amount of a light ray after passing through the filter. It is a graph which shows a characteristic.

FIG. 4A is a configuration diagram showing a conventional example, and FIG. 4B is a graph showing a light amount characteristic of a light ray after passing through a collimator lens.

[Explanation of symbols]

1: light emitting part, 2: collimator lens, 3: optical disc,
4: light receiving element, 5: filter, 51: dye

Claims (2)

[Claims] 1. A light emitting unit, a collimator lens for converting a light beam generated from the light emitting unit into a parallel light beam, an optical disk for transmitting or reflecting a parallel light beam passing through the collimator lens, and an output through the optical disk. In an optical rotary encoder having a light receiving element for receiving a light beam, the concentration of the dye increases with distance from the center, with the optical axis connecting the light emitting unit and the light receiving element as the center, between the collimator lens and the optical disc. An optical rotary encoder characterized by having a filter with a large size. 2. A method of manufacturing an optical rotary encoder, wherein a collimator lens is arranged on a front surface, an optical disc is arranged so as to face the collimator lens, and a light receiving element is arranged so as to face the optical disc. After arranging a film coated with a photosensitive material that is sensitive to the light from the light emitting unit so that the center of the film coincides with the optical axis between the optical disc and the film, the film is irradiated with light rays from the light emitting unit. A method for manufacturing an optical rotary encoder, which comprises developing and fixing the photosensitive material.