Patent ID: 8675008

Claim:
A calculation device comprising: a determination unit arranged to receive a plurality of reflected light intensity information for indicating the intensity of each reflected light which reaches a single light receiver via a reflecting object, the reflected light having been emitted in sequence from a plurality of light emitters provided in mutually different positions, the determination unit further arranged to compute a phase difference of an intensity variation which occurs among the reflected light, and to determine a movement of the reflecting object on the basis of the computed result, wherein said plurality of reflected light intensity information includes first reflected light intensity information for indicating the intensity of a first reflected light that reaches said light receiver from a first light emitter via said reflecting object; second reflected light intensity information for indicating the intensity of a second reflected light that reaches said light receiver from a second light emitter via said reflecting object; and third reflected light intensity information for indicating the intensity of a third reflected light that reaches said light receiver from a third light emitter via said reflecting object; the first, second and third reflected light intensity information being generated by moving-average processing of the most recent L samples respectively; and wherein said determination unit acquires the absolute values of each of at least two phase differences among the phase difference of an intensity variation between the first reflected light and the second reflected light, the phase difference of an intensity variation between the first reflected light and the third reflected light, and the phase difference of an intensity variation between the second reflected light and the third reflected light, and determines the movement axis of said reflecting object on the basis of a size relationship between the acquired absolute values.