Linear encoder for position measurement in e.g. milling machine, has main grid scale arranged along preset arrangement direction, where incident angle of light is inclined at direction that is orthogonal to arrangement direction

摘要

The encoder (8) has a scale (10) comprising a main grid scale (16) arranged along a preset arrangement direction. Another scale (13) has a lower grid scale moved along the arrangement direction. A phototransducer device (14) is placed over the two scales at a side opposite to a light source device, receives light emitted from the device and converts the light into electrical signals. An incident angle of the light is inclined about a preset value at a direction that is orthogonal to the arrangement direction with respect to an incident direction perpendicular to a plane of the former scale.