JPH0347691B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical rotary encoder, and more particularly to a slit plate for an optical rotary encoder.

[Prior art and problems]

For example, as a rotary slit plate for an incremental optical rotary encoder, as shown in FIGS. 4 and 5, a metal vapor deposition film 3 is formed on the surface of a transparent glass disk 1 having a hole 2 in the center, and then a radial pattern is formed. A pattern in which a large number of slit patterns 4 are formed by etching is widely used. This type of slit plate has the advantage of being able to form a large number of narrow optical slits in the circumferential direction with high precision.
There is a disadvantage that the cost is high because expensive materials are used, and the processing cost is also high.

As an inexpensive rotary slit plate for an incremental type optical rotary encoder, a metal disc with a large number of radial slit holes formed by etching from both sides is known. However, it is difficult to form deep narrow slit holes in the thick metal plate of this type of rotary slit plate due to etching technology, and if the slit holes are made shallow, the light transmission performance will deteriorate. This has the disadvantage of deteriorating the encoder function, and therefore, for a metal plate of a certain thickness, the slit width must be selected to be at most about the thickness of the metal plate. Therefore, if the slit width is kept at about the thickness of the plate, the number of slits that can be formed in the circumferential direction is reduced. Furthermore, if the overall thickness of the metal disk is reduced in order to narrow the slit width, a problem arises in that the strength of the metal disk decreases.

[Means for solving problems]

In view of the problems of the prior art described above, the present invention provides an inexpensive slit plate for an optical rotary encoder that is provided with a large number of narrow slits. That is, according to the present invention, the above problem is solved in the slit plate of an optical rotary encoder, the slit plate is made of a metal disc, and the through hole formed in the center of the metal disc and the through hole of the metal disc are A metal disc is formed on at least one surface concentrically with the through hole, has a width in the radial direction between the outer peripheral edge of the metal disk and the inner peripheral edge of the through hole, and has a thin wall thickness. It comprises an annular recess and a number of slit holes formed by etching on the surface of the annular recess and arranged sequentially in the circumferential direction, the slit holes having a length in the radial direction on the surface of the recess. This is achieved by a slit plate of an optical rotary encoder characterized in that the outer peripheral edge is formed into a reinforcing ring.

[Effect]

According to the above means according to the present invention, the slit hole is formed by etching in the annular thin wall portion between the inner circumference and the outer circumference of the metal disk, so that the slit width is made as thin as the thickness of the thin wall portion. be able to.
In addition, since the inner and outer circumferential parts of the metal disc have a larger wall thickness than the thinner part, the inner circumferential part in particular forms a flange for attaching the slit plate to the rotation axis of the optical rotary encoder. Therefore, if this portion is formed with a large thickness, sufficient strength can be ensured from the top to form the rotating slit disk of the rotary encoder. Further, since the annular recess is formed by etching, the thickness of the annular thin portion can be made uniform. Therefore, the width accuracy of the slit hole is improved.
Furthermore, since the metal disk itself is inexpensive and can be easily processed into a disk shape, a highly accurate rotary slit plate can be provided at a low cost.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3 of the drawings.

1 and 2 show one embodiment of the present invention. Referring to these figures, the rotary slit plate of the incremental optical rotary encoder comprises a metal disk 11 with a hole 12 in the center. The metal disk 11 is, for example, a stainless steel plate,
It can be formed by punching a brass plate, copper plate, etc. A hole 12 is formed on one surface of the metal disk 11.
An annular recess 13 extending annularly around the is formed by a common etching process. This recess 1
3, an annular thin wall portion 14 is formed between the inner circumferential portion and the outer circumferential portion of the metal disk 11. The thin portion 14 can be formed to have a thickness of about 30 to 50 μm, for example. A large number of radially extending slit holes 15 are formed in the thin wall portion 14 by a general etching process. In the case of etching treatment,
It is difficult to make the width of the slit hole 15 narrower than the wall thickness of the plate material. However, in this embodiment, since the slit hole 15 is formed in the thin wall portion 14 formed in advance on the metal disk 11, the width of the slit hole 15 can be made as small as the thickness of the thin wall portion 14.

In the rotating slit plate having the above configuration, the slit holes 15 are formed by etching in the annular thin interior 14 between the inner and outer peripheries of the metal disk 11, so the slit width can be adjusted to approximately the thickness of the thin part. It can be made thinner. Further, since the inner circumferential portion and the outer circumferential portion of the metal disk 11 have a wall thickness greater than that of the thin wall portion 14, sufficient strength can be ensured. Furthermore, since the annular recess 13 is formed by etching, the thickness of the annular thin portion 14 can be made uniform. Therefore, the width accuracy of the slit hole 15 is improved. Furthermore, since the metal disk 11 itself is inexpensive and can be easily processed into a disk shape, it can be manufactured at low cost.

FIG. 3 shows another embodiment of the invention. In the figures, the same reference numerals are given to the same components as in the above embodiment. Here, annular recesses 13 are formed on both sides of the metal disk 11 by etching, thereby forming an annular thin wall portion 1 between the inner and outer peripheries of the metal disk 11.
4 is formed. The slit hole 15 is formed in this annular thin-walled portion 14 by etching as in the above embodiment.

Although the embodiments have been described above, the present invention is not limited to the embodiments described above; for example, the present invention can be similarly applied to a slit plate of an absolute type optical rotary encoder.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the slit hole is formed by etching in the annular thin-walled portion between the inner and outer circumferential portions of the metal disk. It becomes possible to make it as thin as the wall thickness. In addition, since the inner and outer peripheral parts of the metal disc have a larger wall thickness than the thinner parts, even if the annular recess is partially thin, the strength of the metal itself can be ensured, and Particularly thick on the inner periphery ensures that the flange part that attaches the slit plate to the rotating shaft of the rotary encoder is thick and strong, ensuring sufficient strength as the rotary slit plate of the rotary encoder. I can do it. Furthermore, as is clear from the above, the slit plate of the optical rotary encoder according to the present invention is provided with a reinforcing ring having a wall thickness larger than the thin wall portion in which the slit holes are formed at the outer peripheral edge. The rigidity of the slit plate is increased, and therefore, the slit plate does not cause any wavering phenomenon even when rotating, especially when rotating at high speed. Therefore, the rotation detection waveform becomes a stable output waveform that is inexpensive to electrically process. It is also effective. Further, since the annular recess is formed by etching, the thickness of the annular thin portion can be made uniform. In short, only the portion where a narrow slit hole is to be formed is formed into an annular recessed structure and the wall is made thinner, and the slit hole is bored on the surface of the recess after the thinner wall, so that the slit width can be narrowed. At this time, etching the thinned portion increases the width accuracy of the slit hole. Furthermore, since the metal disk itself is inexpensive and can be easily processed into a disk shape, a highly accurate rotary slit plate can be provided at a low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view taken along the line - in FIG.
The figure is a schematic front view of the rotating slit plate shown in Figure 1;
FIG. 3 is a schematic sectional view of a rotary slit plate showing another embodiment of the present invention, FIG. 4 is a schematic front view of a rotary slit plate of a conventional incremental optical rotary encoder, and FIG. FIG. 3 is a schematic cross-sectional view of the rotating slit plate shown in FIG. 11... Metal disc, 12... Hole, 13... Annular recess,
14...Thin wall part, 15...Slit hole.

Claims (1)

[Claims] 1. In a slit plate for an optical rotary encoder, the slit plate is made of a metal disc, and has a through hole formed in the center of the metal disc, and a through hole formed concentrically with the through hole on at least one surface of the metal disc. an annular recess having a width in the radial direction and a thin wall thickness between the outer peripheral edge of the metal disk and the inner peripheral edge of the through hole; and a surface of the annular recess. a plurality of slit holes formed by etching and arranged sequentially in the circumferential direction, the slit holes having a length in the radial direction on the surface of the recess, and an edge of the outer periphery forming a reinforcing ring. This is a slit plate for an optical rotary encoder.