Patent ID: 9234772
Filing Date: 2016-01-12
CPC Classification: G01D

Claim Text:
1. An optical encoder comprising; a scale provided with a periodic pattern in which an optical portion reflecting or transmitting light is periodically formed with a first period in a first direction; and a light receiver configured to photoelectrically convert a detection light emitted from a light source and then passing via the scale into an output signal having a change period corresponding to the first period, wherein the scale and the light receiver are relatively movable in the first direction, wherein the optical portion is configured to direct the light from the light source to the light receiver, wherein, when a direction orthogonal to the first direction in the periodic pattern is defined as a second direction, the optical portion periodically has a pattern, which is formed pattern portions mutually adjacent in the second direction and mutually shifted in the first direction, in the second direction with a second period of t, and wherein a width w of the light source in the second direction satisfies the following condition: where n represents a natural number, and a:b represents a ratio of a distance from the light source to the periodic pattern and a distance from the periodic pattern to the light receiver.