Patent ID: 8742322

Claim:
An optical encoder comprising: a grating scale configured to be movable; a light-receiving device configured to receive light via the grating scale irradiated with light, to generate N-phase signals that have respective phases different from each other, where N is an integer not smaller than 6; and an amplifier configured to: multiply the generated N-phase signals by M coefficient sets that are different from each other, where M is an integer not smaller than 2; and obtain a sum of the multiplied values with respect to each of the M coefficient sets to generate M-phase signals, wherein the M coefficient sets are represented by following expressions: G ⁢ ⁢ 1 ⁢ ( k ) = { 1 + sin ⁡ ( 1 / N × 2 ⁢ π + π × ( k - 1 ) / M ) ] / 2 , ⁢ G ⁢ ⁢ 2 ⁢ ( k ) = { 1 + sin ⁡ ( 2 / N × 2 ⁢ π + π × ( k - 1 ) / M ) } / 2 , ⁢ G ⁢ ⁢ 3 ⁢ ( k ) = { 1 + sin ⁡ ( 3 / N × 2 ⁢ π + π × ( k - 1 ) / M ) ] / 2 , ⁢ … G ⁢ ⁢ N ⁡ ( k ) = { 1 + sin ⁡ ( N / N × 2 ⁢ π + π × ( k - 1 ) / M ) } / 2 , ⁢ where ⁢ ⁢ k = 1 , 2 , … ⁢ , M .