JPH0723222U - Optical encoder - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an optical encoder that is resistant to damage, can reduce manufacturing costs, can obtain high resolution, and is resistant to temperature and humidity. [Structure] Since the coating material 8 of silicone is applied to the entire pulse disk 6, the coating material 8 protects the lattice pattern of the pulse disk 6 from high temperature and high humidity when used under high temperature or high humidity. It is possible to prevent a change in the pattern shape and a partial dropout of the pattern, which enables stable and highly accurate measurement. As a result, the weakness of the film disk, which is weak against temperature and humidity, is overcome, the film is hard to break, the manufacturing cost can be reduced, and high resolution can be achieved to the maximum.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical encoder, and more particularly to an optical encoder having a pulse disc formed of film.

[0002]

[Prior art]

 FIG. 3 is a vertical sectional view of a conventional optical encoder.

As shown in FIG. 3, the conventional optical encoder includes a pulse disk 106 having a lattice pattern 111 along the circumferential direction, and a light source 110 for irradiating the pulse disk 106 with light. It is provided with a light receiving element 109 which is arranged to face the light source 110 via the pulse disk 106 and receives the passing light from the pulse disk 106.

The pulse disk 106 is often formed of glass or metal, but in the case of glass, it is easily broken and the manufacturing cost is high, and in the case of metal, fine slits cannot be formed by etching. There is a problem of low resolution.

Therefore, as disclosed in Japanese Utility Model Publication No. 60-127510, a polyester film is conventionally used as a material for a pulse disc.

The polyester film pulse disk disclosed in Japanese Utility Model Laid-Open No. 60-127510 is constructed by laminating a disk made of a transparent organic material (polyester or glass) on a polyester film having slits. It is a thing.

[0007]

[Problems to be solved by the device]

 Generally, the grid pattern of this polyester film pulse disc is formed by a method such as the following photo printing.

Specifically, a transparent polyester serving as a base is coated with a photosensitive emulsion, and an original plate having a reference lattice pattern on the coated surface of the photosensitive emulsion (hereinafter referred to as emulsion surface) is exposed (or printed).

After exposure of the reference lattice pattern, a photographic process such as development is performed to form a polyester film pulse disc having a lattice pattern.

In the conventional poly-ester film pulse disc, a disc made of a transparent organic material (polyester, glass, etc.) is attached to a polyester film having a lattice pattern on the back side of the lattice pattern forming surface, so It has the advantage that surface run-out can be reduced by increasing the mechanical strength of the plate, and it can be attached to machine tools, etc. that vibrate.

However, when an encoder equipped with a polyester film pulse disk is used under a place of high temperature or high humidity, the emulsion surface is easily affected by temperature and humidity, and the emulsion surface is deteriorated. Part of the lattice pattern formed on the emulsion surface may be peeled off from the base polyester.

The present invention has been made in view of such circumstances, and an object thereof is to provide an optical encoder provided with a polyester film pulse disk having a lattice pattern that is resistant to environment, particularly high temperature or high humidity. It is to be.

[0013]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the optical encoder of the present invention is formed of a film, is attached to a rotary shaft, and has a pulse disc with a lattice pattern along the circumferential direction, and an optical disc on this pulse disc. And a light receiving unit that is arranged to face the light source through the pulse disc and receives the passing light from the pulse disc. Based on a signal from the light receiving unit, the rotation shaft In an optical encoder for detecting the amount of rotation, at least the surface of the pulse disk lattice pattern is coated with a transparent coating material having moisture resistance.

[0014]

[Action]

 Even when used under high temperature or high humidity, the transparent and moisture-resistant coating protects the pulse disc grid pattern from high temperature and high humidity, so the pattern does not deteriorate and is stable and highly accurate. It becomes possible to measure. As a result, the weakness of the film disc, which is weak against temperature and humidity, is overcome.

[0015]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of an optical encoder according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a pulse disc.

The rotating shaft 1 is rotatably supported by bearings 3 and 4 attached to a housing 2. A collar portion 1a is provided on the outer periphery of the upper end portion of the rotating shaft 1, and a cylindrical boss portion 1b is provided on the upper end surface 5 of the rotating shaft 1.

An annular polyester film pulse disk (hereinafter referred to as a pulse disk) 6 is bonded to the upper end surface 5 of the rotating shaft 1. The inner diameter of the pulse disc 6 is slightly larger than the outer diameter of the cylindrical boss portion 1b, and when the pulse disc 6 is adhered to the upper end surface 5 of the rotating shaft 1, the boss portion 1b of the rotating shaft 1 has the pulse disc 6 Escape upward from the hole 6a.

A holding ring 7 is attached to the boss portion 1b of the rotating shaft 1, and the pulse disk 6 is held so as to be pressed against the upper end surface 5 of the rotating shaft 1.

As described above, the pulse disk 6 has a transparent polyester serving as a base coated with a photosensitive emulsion, and the coated surface of the photosensitive emulsion (hereinafter referred to as an emulsion surface) is provided with a reference lattice pattern. Expose the master plate.

After the exposure of the reference lattice pattern, the pulse disc 6 having the lattice pattern 12 is formed by performing photographic processing such as development.

The lattice pattern 12 has light-transmitting portions and light-shielding portions arranged alternately, and is formed along the circumferential direction of the pulse disk 6.

Then, as shown in FIG. 2, a transparent coating agent 8 of, for example, low-viscosity silicone is applied to the lattice pattern 12 of the pulse disk 6 by dipping, spraying, brushing or the like. The thickness t of the coating agent 8 is several microns.

As a condition of the coating agent, an epoxy resin (epoxy resin) or a silicone resin (silicone resin) having moisture resistance and adhesive strength is preferable.

A light emitting element 10 such as a light emitting diode is disposed below the pulse disk 6, and the light emitting element 10 faces a part of the lattice pattern of the pulse disk 6. A light receiving element 9 such as a photodiode is provided above the pulse disk 6, and the light receiving element 9 and the light emitting element 10 face each other with the pulse disk 6 interposed therebetween. A fixed slit 11 is arranged between the light emitting element 10 and the pulse disk 6.

The light from the light emitting element 10 is applied to the pulse disk 6 via 11, and the light transmitted through the pulse disk 6 is received by the light receiving element 9 and photoelectrically converted, and the detection signal is output from the light receiving element 9. To be done. Then, the rotation amount of the rotary shaft 1 is detected from the light receiving element 9 based on the detection signal.

According to the optical encoder of this embodiment, the pulse disk 6 is coated with the low-viscosity silicone coating agent 8. Therefore, the optical encoder is used, for example, under high temperature and humidity in a rainy season factory. As a result, the lattice pattern formed on the emulsion surface of the pulse disk 6 is melted, and the pattern shape does not change or a part of the pattern falls off. It becomes possible to measure. That is, by fixing the lattice pattern 12 formed on the emulsion surface of the coating agent to the polyester which is the base, it is possible to prevent the lattice pattern from separating from the polyester base. Therefore, the weakness of the film disc, which is weak against temperature and humidity, can be overcome, it is less likely to be damaged, the manufacturing cost can be reduced, and the features of the film disc that can obtain high resolution can be fully utilized.

In the above-mentioned embodiment, the case where the coating agent 8 is applied to one side of the pulse disk 6 has been described. However, instead of this, the coating agent 8 is applied to both sides of the lattice pattern of the pulse disk 6. You may do it. Further, the thickness t of the applied coating agent 8 is preferably thin in view of the light transmittance and the surface deviation due to the uneven thickness.

Further, in the above-mentioned embodiment, the case where the low-viscosity silicone resin is used as the coating agent 8 has been described, but instead of this, the epoxy resin may be used as described above. However, it can be said that the silicone resin is superior to the epoxy resin in mass productivity or workability because it is harder to be solidified during depping.

Further, in the above-mentioned embodiment, the case where the coating material 8 is applied to the pulse disk 6 has been described, but instead of this, a thin transparent plate may be attached to one surface of the pulse disk 6.

The fixed slit 11 may also be formed of a film, and the coating agent 8 may be applied to the surface thereof.

[0032]

[Effect of device]

 As described above, according to the optical encoder of the present invention, since the coating agent is applied to the pulse disc, it is not easily affected by changes in temperature and humidity, and stable and highly accurate measurement is possible. . Therefore, it is less likely to be damaged even under high temperature or high humidity, the manufacturing cost can be reduced, and the advantage of the film disk that high resolution can be obtained can be utilized.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an optical encoder according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a pulse disc.

FIG. 3 is a vertical cross-sectional view of a conventional optical encoder.

[Explanation of symbols]

 1 Rotation axis 6 Pulse disk 8 Coating agent 9 Light receiving element 10 Light emitting element

Claims (1)

[Scope of utility model registration request] 1. A pulse disc formed of a film, attached to a rotary shaft, and provided with a lattice pattern along the circumferential direction, a light source for irradiating the pulse disc with light, and the pulse disc. An optical encoder which is arranged to face the light source via the light receiving means for receiving the passing light from the pulse disc, and which detects the rotation amount of the rotating shaft based on a signal from the light receiving means, An optical encoder, characterized in that a transparent and moisture-resistant coating agent is applied to the surface of the lattice pattern of the pulse disk.