JPH0442603B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for attaching a slit plate to an optical rotation detection device that detects rotation of a rotating body such as a motor with high precision.

Conventional Structure and Problems In recent years, since motors used in audio equipment and video equipment require highly accurate speed control, it has become important to obtain a highly accurate frequency generator.

A conventionally proposed optical single-point detection type frequency generator will be described below. In FIG. 1, to briefly explain the configuration of an optical single-point detection type frequency generator, light 1a emitted from a light emitting element 1 passes through a plurality of slits 3a of a slit plate 3 attached to a rotating shaft 2. The light is projected onto the photoelectric conversion element 4. Since this slit plate 3 rotates together with the rotating shaft 2, the photoelectric conversion element 4 is irradiated with light 1a from the light emitting element 1, as shown in FIG.
As shown in FIG. 3B, cases in which light is blocked by the rotating slit plate 3 occur alternately. Therefore, the photoelectric conversion element 4 outputs an AC signal. However, it is well known that the AC signal obtained by this method is directly affected by eccentricity, warpage, and inclination when the slit plate 3 is attached to the rotating shaft 2, as well as the accuracy of the slit 3a. There is.

FIG. 3 shows a conventional example of a method for attaching a slit plate to the above-mentioned optical rotation detection device. In Fig. 3, 2 is the rotating shaft, 5 is the rotor boss, and 3 is n
A slit plate 6 has a number of slits 3a, and 6 is a holding plate for the slit plate. In the same figure, the method of attaching the slit plate 3 is explained by press-fitting the rotating shaft 2 into the rotor boss 5, then inserting the slit plate 3 into the rotating shaft 2, holding it down with the slit plate holding plate 6, and fixing it with a mounting screw or welding. It is then installed and fixed.

However, in the above configuration, a clearance d is generated between the mounting hole 3b of the rotating shaft 2 provided at the center of the slit plate 3 and the outer diameter of the rotating shaft 2, as shown in FIGS. 4a and b. However, the slit 3a of the slit plate 3 is eccentric with respect to the rotating shaft 2 corresponding to this clearance d, which deteriorates the detection accuracy of the frequency generator, as explained in FIGS. 1 and 2. It had some problems.

FIG. 5 shows a cross-sectional view of another conventional example of a slit plate mounting method for an optical rotation detection device, in which a rotary shaft mounting hole smaller than the outer diameter of the rotary shaft 2 is provided in the center of the rotary slit plate 7. 7b, and is press-fitted into the rotating shaft 2, so that the rotating shaft 2 can be attached with the clearance d as described above.
The eccentricity of the slit 7a of the slit plate 7 can be reduced based on the slit plate 7, but since the slit plate 7a is made of a very thin plate, the slit plate 7 may warp or be irregular as shown by the broken line 7c during press-fitting. Therefore, as explained in FIGS. 1 and 2, there is a problem in that the detection accuracy of the frequency generator is deteriorated.

Purpose of the invention The present invention solves the above-mentioned conventional problems.
The purpose is to improve the warpage and irregular inclination of the slit plate or the warp of the slit plate based on the rotation axis when press-fitting the rotation shaft mounting hole formed in the center of the slit plate onto the rotation shaft. be.

Composition of the Invention The present invention relates to a method for attaching a slit plate to an optical rotation detection device that includes a rotating shaft, a rotor boss, a slit plate, and a slit plate holding plate. By forming a rotating shaft mounting hole where the thickness of the plate becomes thinner towards the end, making the rotating shaft mounting hole equal to or smaller than the outer diameter of the rotating shaft, and fixing it by press-fitting onto the rotating shaft,
This is to improve the eccentricity of the slit plate with respect to the rotating shaft, the warpage and irregular inclination of the slit plate.

DESCRIPTION OF THE EMBODIMENTS FIGS. 6 and 7 are sectional views showing a method of attaching a slit plate to an optical rotation detection device according to an embodiment of the present invention. In FIGS. 6 and 7, 2 is a rotating shaft, 5 is a rotor boss, and 8 is a rotor having n slits 8a, and is formed by etching in the center so as to become thinner toward the rotating shaft 2. Slit plate 6 having shaft mounting hole 8b
is the slit plate holding plate. Referring to the figure, a method for attaching the slit plate 8 will be explained. As described above, the slit plate 8 is etched to form a rotating shaft mounting hole 8b in the center thereof, which has a portion 8c where the plate thickness becomes thinner toward the rotating shaft 2. It is attached by press-fitting and fixing the slit plate 8 to the rotating shaft 2 using the thinner portion 8c of the slit plate 8 so that the diameter is equal to or less than the diameter.

As described above, according to this embodiment, the rotating shaft 2 formed at the center of the slit plate 8 is formed by etching.
The following effects can be achieved by press-fitting and fixing the rotary shaft 2 to the rotary shaft 2 by utilizing the thinning portion 8c of the rotary shaft mounting hole 8b. That is, (a) since there is no clearance d between the rotating shaft 2 and the rotating shaft mounting hole 8b, the eccentricity of the slit plate with respect to the rotating shaft corresponding to the ratio of the clearance d is improved.

(b) Since the thinner part 8c of the slit plate 8 is used to press-fit and fix it to the rotating shaft 2, only a small press-fitting load is required, so there is no possibility of warpage or irregular inclination of the slit plate 8 with respect to the rotating shaft 2. can be improved.

Effects such as this can be obtained.

In the above embodiment, the slit plate 8 has n slits 8a, but it may have a plurality of types of slits. The portion 8c that becomes thinner in the direction does not remain in the shape shown in FIG.
It goes without saying that any material having the same function as the part 8c that tapers toward the end is sufficient.

Effects of the Invention As is clear from the above description, the present invention forms a rotating shaft mounting hole in the center of a slit plate by etching a portion where the thickness of the plate becomes thinner toward the rotating shaft. Since the thinner part is press-fitted and fixed to the rotary shaft 2 so that the outer diameter is equal to or less than the outer diameter of the shaft, the following effects are achieved.

(a) Since there is no clearance between the rotating shaft and the rotating shaft mounting hole, eccentricity of the slit plate due to the clearance can be eliminated, and the detection accuracy of the frequency generator can be improved.

(b) Since the thin part of the rotary shaft mounting hole in the center of the slit plate is used to press fit onto the rotary shaft, warping or irregular tilting of the slit plate can be improved, and the detection accuracy of the frequency generator can be improved. can be improved.

This makes it possible to realize an excellent method for attaching a slit plate to an optical rotation detection device that can achieve the following effects.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view showing a conventional optical single-point detection type frequency generator, Fig. 2 a and b are explanatory diagrams of the same operation, and Fig. 3 shows how to attach a slit plate of a conventional optical rotation detection device. 4a and 4b are cross-sectional views showing an example of poor mounting in the slit plate mounting method of the same optical rotation detection device, and FIG. 5 is a slit plate mounting method of another conventional optical rotation detection device. FIG. 6 is a cross-sectional view showing how to attach the slit plate of the optical rotation detection device according to the embodiment of the present invention, and FIG. 7 is an enlarged cross-sectional view showing the relationship between the slit plate and the rotation axis in FIG. 6. It is. 2... Rotating shaft, 8... Slit plate, 8a... Slit, 8b... Rotating shaft mounting hole, 8c... Portion where the plate thickness becomes thinner toward the rotating shaft.

Claims (1)

[Claims] 1. A rotating shaft mounting hole is formed in the center of a slit plate having n slits by etching, and the plate thickness becomes thinner toward the rotating shaft. A method for attaching a slit plate of an optical rotation detection device, the slit plate being press-fitted to the rotating shaft with the same or smaller diameter.