US Patent 7256712 Encoder having a signal elimination unit

An encoder includes an encoder scale having a predetermined cyclic pattern, and at least one detection unit configured to detect a cyclic displacement according to movement of the encoder scale. The encoder further includes a signal elimination unit configured to subtract, from an output signal of the at least one detection unit, one of an entirety of a DC signal component, which is free from dependency on a relative displacement of the encoder scale, and a signal component that is proportional to the DC signal component.