Patent ID: 8415610
Filing Date: 2013-04-09
Classification: G01D

Abstract:
1. An optical encoder comprising: a light source; a single signal track arranged on a subject of measurement and configured to modulate a luminous flux from the light source in accordance with a movement of the subject of measurement; an optical detecting part configured to receive the luminous flux from the signal track and convert the luminous flux to an electrical signal, and output the electrical signal; and an operating unit configured to operate on the output signal of an optical detector; the signal track including a configuration configured to sinusoidally modulate an intensity of the light from the light source and give the sine-wave a phase modulation which is repeated for every mλ=Λ (the m being a natural number), where the λ being a fundamental period, the optical detecting part extracting a sine signal and a cosine signal from the luminous flux modulated sinusoidally by the signal track giving the phase modulation, and wherein by the operating unit, signals with two periods from the single signal track are obtained, one of which is a fundamental period signal with the fundamental period λ and the other is a phase-modulated signal with the period Λ.