Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1990-04-20
1992-09-08
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
250237G, 427232, G01D 534
Patent
active
051460840
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
BACKGROUND OF THE INVENTION
The present invention relates to a structure for mounting a rotary code disk on a rotary shaft of an optical encoder for use in combination with a servomotor, a machine tool or a measuring apparatus.
FIG. 4A is a schematic sectional view of a conventional rotary code disk mounting structure, FIG. 4B is an enlarged sectional view of an essential portion of the same rotary code disk mounting structure, and FIG. 4C is an exploded perspective view of the same rotary code disk mounting structure. Referring to FIGS. 4A, 4B and 4C, when mounting rotary code disk 3 made from 3 mm thick glass and having a central hole 30 on a spindle 2, the rotary code disk 3 is placed on the lapped support surface 20 of the spindle 2, a ring 4 is put on the head 25 of the spindle 2 projecting through the central hole 30 of the code disk 3, the ring 4 is depressed with a jig so that the tongues 41 of the ring 4 are bent to fasten the code disk 3 temporarily on the support surface 20, the code disk 3 is centered with a microscope while the spindle 2 is rotated, and then the ring 4 is buried in an adhesive J to fasten the code disk 3 to the spindle 2.
This conventional rotary code disk mounting structure fastens the code disk 3 to the spindle 2 by bonding a portion of the upper surface of the code disk 3 around the central hole 30 and the outer circumference of the projecting head 25 with the adhesive J. Therefore, the diameter D.sub.0 of the head 25 must be comparatively large to secure a desired fastening strength, and thus the diameter of the center hole 30 of the code disk 3 must be comparatively large. The center hole 30 reduces the impact strength of the glass code disk 3, and thus the code disk 3 provided with the center hole 30 must be comparatively thick. Furthermore, the code disk 3 provided with the center hole 30 requires an additional process for forming the center hole 30.
The present invention is intended to eliminate the foregoing disadvantages by employing a novel mounting structure.
SUMMARY OF THE INVENTION
As shown in FIGS. 1 and 2A, by way of example, a rotary code disk 3 having no center hole is placed on the top surface 20 of a spindle 2 provided with a central recess 21 and a plurality of peripheral cuts 22, and the central portion of the backside of the rotary code disk 3 is bonded to the top surface 20 by an adhesive J contained in the recess 21.
Since the rotary code disk is not provided with a center hold such as the center hole 30 of the conventional rotary disk (FIG. 4C), the strength of the rotary disk of the present invention is higher than the conventional rotary code disk having a thickness the same as that of the former.
Also the omission of a process of forming a central hole in the code disk 3 and the ring 4 for temporarily fastening the code disk to the spindle rationalizes the, code disk fabricating and assembling processes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation showing a rotary code disk mounting structure embodying the present invention;
FIG. 2A is an exploded perspective view of the rotary code disk mounting structure of FIG. 1;
FIG. 2B is a sectional view of an essential portion of the rotary code disk mounting structure of FIG. 1;
FIG. 3 is a view of assistance in explaining a manner of centering in accordance with the present invention;
FIG. 4A is a side elevation of a conventional rotary code disk mounting structure;
FIG. 4B is a sectional view of an essential portion of the rotary code disk mounting structure of FIG. 4A; and
FIG. 4C is an exploded perspective view of the rotary code disk mounting structure of FIG. 4A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Example 1
As shown in FIGS. 1 and 2A, rotary code disk 3 has the same size and shape as the conventional rotary code disk, except that the rotary code disk 3 is not provided with a center hole.
A flange 1 is of a conventional type. A spindle 2 has a lapped mounting surface 20 of 20 mm in diameter provided with a central circular recess 21 of 14 mm i
REFERENCES:
patent: 1747678 (1930-02-01), Neely et al.
patent: 2319657 (1943-05-01), Brown
patent: 4295573 (1981-10-01), Terry et al.
Asaba Eiki
Tanabe Yoshihito
Davenport T.
Fanuc Ltd.
Nelms David C.
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