JPH07270185A - Optical encoder - Google Patents

Abstract

PURPOSE:To prevent a deformation by balancing an amount of thermal expansion of both surfaces of a rotary disc by applying a photosensitive material of the same material to the surfaces of the rotary disc or the like manner. CONSTITUTION:A rotary disc 3 consists of a transparent first film disc 33 and a transparent second film disc 34. A photosensitive material is applied to one surface of the first film disc 33 and a slit surface 31 is formed by a photographic printing method. The same photosensitive material as used for the first film disc 33 is applied to one surface of the second film disc 34 to form a transparent surface 32 all over the one surface. A transparent adhesive 35 is applied to the other surfaces of the discs not coated with the photosensitive material, thereby bonding the discs. The rotary disc 3 is thus integrated. Since the components of the rotary disc are symmetric to each other to a center line in a thicknesswise direction, an amount of thermal expansion is kept balanced even at high temperatures, so that no deformation is brought about.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical encoder for detecting a rotation angle of a rotating body and a moving position of a moving body.

[0002]

2. Description of the Related Art Conventionally, an optical encoder for detecting a rotation angle has a rotating disk provided with a plurality of slits in the circumferential direction, and a fixed slit portion provided on one side of the rotating disk with a gap therebetween. A light emitting element and a light receiving element are provided so as to sandwich both the rotating disk and the fixed slit, and a signal processing circuit that processes a detection signal detected by the light receiving element. The rotating disk is
There is a method in which chromium is vapor-deposited on one side of a glass substrate and a slit is formed by a photo printing method, and a method in which a slit is formed on a metal disk by using an etching method, but the cost is high and the dimensional accuracy cannot be obtained. I have a problem. In order to solve this problem, a thin metal film is attached to one surface of a transparent film base made of a plastic resin, and a slit is formed in the thin metal film by a photo printing method (for example, Japanese Patent Laid-Open No. Sho 60). No. 119415), or one in which a photosensitive material is applied to one side of a transparent film base material and slits are formed by a photographic printing method (for example, Japanese Patent Laid-Open No.
No. 210822) is disclosed.

[0003]

However, in the prior art, the rotating disk is formed by sticking a metal thin film on one side of the film substrate or coating a photosensitive material. Alternatively, there is a difference in coefficient of thermal expansion between the film base material and the photosensitive material containing gelatin as a main component. Therefore, at the time of high temperature during use, there is a problem that a phenomenon of bending like a bimetal occurs due to a difference in thermal expansion amount, and the rotating disk comes into contact with the light emitting element or the fixed slit portion. Further, once the temperature becomes 100 ° C. or higher, there is a drawback that the original planar shape is not restored even if the temperature is returned to room temperature. It is an object of the present invention to provide an optical encoder that has a small amount of deformation and high accuracy.

[0004]

In order to solve the above problems, the present invention provides a slit surface having a plurality of slits in the circumferential direction by applying a photosensitive material to a transparent film disk having a plastic resin as a base material. A rotating disc formed, a fixed slit portion provided on one side of the rotating disc with a gap, and a light emitting element and a light receiving element arranged so as to sandwich both the rotating disc and the fixed slit portion. In the optical encoder including a signal processing circuit that processes a detection signal detected by the light receiving element, the rotating disk is the same as the first film disk having the slit surface and the slit surface. A second film disk having a transparent surface made of a material is integrally formed by adhesion so that the slit surface and the transparent surface are on the outside. The rotating disk may be formed by inserting and adhering one or more intermediate film disks between the first film disk and the second film disk.

[0005]

By the above means, the photosensitive material of the same material is applied to both surfaces of the rotating disk, so that the constituent elements are symmetrical with respect to the center line in the thickness direction and rotate even at high temperature. The thermal expansion amounts on both sides of the disk are balanced, and no deformation such as bending occurs.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first example of an optical rotary encoder of the present invention.
FIG. 3 is a schematic side sectional view showing the embodiment of FIG. In the figure, a rotating disk 3 is fixed to a rotating body 1 via a hub 2. A fixed slit portion 4 is provided on one side of the rotating disc via a gap, and a light emitting element 5 and a light receiving element 6 are provided so as to sandwich the rotating disc 3 and the fixed slit portion 4, and the light receiving element 6 has The signal processing circuit 7 is connected. The rotating disk 3 is composed of a transparent first film disk 33 and a transparent second film disk 34, and one surface of the first film disk 33 is coated with a photosensitive material to photograph. The slit surface 31 is formed by the printing method. The same photosensitive material as the photosensitive material in which the slit surface 31 is formed on the first film disk 33 is applied to one surface of the second film disk 34 to form a transparent surface 32 which is transparent on the entire surface. The first film disc 33 and the second film disc 34 are coated with a transparent adhesive 35 on the surface not coated with the photosensitive material and adhered to each other to form an integral rotating disc 3. is there. Therefore, since the photosensitive material of the same material is applied to both surfaces of the rotary disk 3, the first film disk 33 and the second film disk 34 are formed.
The constituent elements are symmetric with respect to the bonding surface of the rotating disk, that is, with respect to the center line in the thickness direction of the rotating disk, and even if the temperature rises, the thermal expansion amount is balanced and no deformation occurs. In order to increase the strength of the rotating disc 3, as shown in FIG. 2, one or a plurality of intermediate film discs 36 are provided between the first film disc 33 and the second film disc 34. May be inserted and fixed to each other with an adhesive 35 to form an integral rotating disc 3. In addition, although the above-described embodiment has described the optical rotary encoder, instead of the rotating disk, a moving slit plate in which a plurality of slits are arranged in a linear direction is configured by a plurality of film plates, and one of the moving slit plates is used. By forming a slit surface on the surface and a transparent surface on the other surface,
It is also applicable to an optical linear encoder that detects the position of a moving body that moves in a linear direction.

[0007]

As described above, according to the present invention, the components are symmetrical with respect to the center line in the thickness direction of the rotating disk so that the thermal expansion amount is balanced even at high temperatures. As a result, no deformation occurs, so that there is little deformation of the rotating disk and there is an effect that an optical encoder with high accuracy can be provided.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a side sectional view showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 rotating body, 2 hub, 3 rotating disk, 31 slit surface, 32 transparent surface, 33 1st film disk, 34
2nd film disk, 35 adhesive, 36 intermediate film disk, 4 fixed slit part, 5 light emitting element, 6 light receiving element, 7 signal processing circuit

Claims (2)

[Claims] 1. A rotating disk having a slit surface having a plurality of slits in a circumferential direction formed by applying a photosensitive material to a transparent film disk having a plastic resin as a base material, and one side of the rotating disk. A fixed slit portion provided with a space in between, a light emitting element and a light receiving element arranged so as to sandwich both the rotating disk and the fixed slit portion, and a signal processing circuit for processing a detection signal detected by the light receiving element. In the optical encoder provided with, the rotating disk includes a first film disk having the slit surface and a second film disk having a transparent surface made of the same material as the slit surface. Is integrally formed by bonding so that the slit surface and the transparent surface are on the outside. 2. The rotating disc is integrally formed by bonding by inserting one or a plurality of intermediate film discs between the first film disc and the second film disc. The optical encoder described.