Encoder and apparatus using the same

Patent metadata

Field	Value
Publication number	US-9103699-B2
Application number	US-201313873476-A
Country	US
Kind code	B2
Filing date	Apr 30, 2013
Priority date	May 2, 2012
Publication date	Aug 11, 2015
Grant date	Aug 11, 2015

Abstract

The encoder includes a scale having a first periodic pattern and a second periodic pattern, a sensor relatively movable with the scale. The sensor outputs in a first detection state a first periodic signal changing with a change period corresponding to the first periodic pattern and outputs in a second detection state a second periodic signal changing with a longer change period corresponding to the second periodic pattern than that of the first periodic signal. A processor calculates a position in a relative movement direction of the scale and sensor by using both the first and second periodic signals. The processor takes in the second periodic signal, the first periodic signal and the second periodic signal in this order at mutually different times, calculates phases of the second, first and second periodic signals at a specific time and calculates the position at the specific time by using the calculated phases.

First claim

What is claimed is:

1. An encoder comprising:
a scale provided with a first periodic pattern and a second periodic pattern whose period is different from that of the first periodic pattern;
a sensor relatively movable with the scale and switchable to a first detection state to read the first periodic pattern and a second detection state to read the second periodic pattern, the sensor being configured to output in the first detection state a first periodic signal that changes wit…

Assignees

• Canon Kk

Inventors

• Nakamura Hitoshi

Classifications

• G01D5/34776 Primary

  Physics · mapped topic

• G01D5/34746

  Physics · mapped topic