Scale for photoelectric encoder

Patent metadata

Field	Value
Publication number	US-9310225-B2
Application number	US-201414284902-A
Country	US
Kind code	B2
Filing date	May 22, 2014
Priority date	Jun 14, 2013
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

A scale for a photoelectric encoder includes a scale substrate and a reflection film formed at a predetermined pitch on the scale substrate. A surface of the reflection film forms a reflection surface. A low-reflection surface is formed by etching the scale substrate between reflection films. Accordingly, a scale can be provided which is lower in cost and has favorable yield rates.

First claim

What is claimed is:

1. A scale for a photoelectric encoder comprising:
a stainless steel scale substrate;
a plurality of chrome reflection films each having a thickness of 25 nm to 200 nm and located on the substrate at a predetermined pitch, the plurality of reflection films comprising a reflection surface; and
a low-reflection surface between reflection films of the plurality of reflection films and formed by etching the scale substrate.

2. The scale for the photoelectric encoder according to claim 1 , wherein the scale substrate is Special Use Stainless Steel.

3. The scale for the photoelectric encoder according to claim 1 , wherein the scale substrate is Invar material.

4. The scale for the photoelectric encoder according to claim 1 , wherein the reflection film is adhesive with the scale substrate.

5. An encoder comprising:
a stainless steel scale substrate;
a scale arranged on the scale substrate, the scale comprising:
a low-reflection surface in which the substrate is etched at a predetermined pitch and in an orthogonal direction on top of the scale substrate; and
a light reflection surface having a chrome reflection film with a higher reflectance than the low-reflection surface formed in a region between where the low-reflection surfaces are formed and following a direction orthogonal to a measurement direction of the scale, the chrome reflection film having a thickness of 25 nm to 200 nm; and
a reader configured to read the scale.

6. A method of forming a scale having a low-reflection surface and a light reflection surface, the method comprising:
forming, on a polished surface of a stainless steel substrate, a chrome reflection film adhesive with a scale substrate and a higher reflectance than the low-reflection surface, the reflection film having a thickness of 25 nm to 200 nm;
etching a portion of the reflection film at fixed intervals and in a direction orthogonal to a measurement direction of the scale to form the light reflection surface; and
etching the reflection film, then further etching a region where a polished surface of the substrate is exposed to form the low-reflection surface.

Assignees

• Mitutoyo Corp

Inventors

• Maeda Fujio

Classifications

• G01D5/34746

  Linear encoders · CPC title

• G01D5/34707 Primary

  Scales; Discs, e.g. fixation, fabrication, compensation · CPC title