| 摘要 |
Three light emitting elements (3) to (5) and one light receiving element (6) are provided on a surface (2A) of a substrate (2). An arithmetic processing portion (15) of a signal processing circuit (11) separates three reflected light signals (Sr1) to (Sr3) from a light detection signal (SO) from the light receiving element (6). The arithmetic processing portion (15) calculates a square sum of the difference between the entire waveforms of the reflected light signals (Sr1) and (Sr2) while the reflected light signal (Sr2) is shifted. The arithmetic processing portion (15) calculates a phase difference (T21) between the reflected light signals (Sr1) and (Sr2) on the basis of a shift amount (X21) with which the calculated value is minimum. On the basis of similar processing, the arithmetic processing portion (15) calculates a phase difference (T32) between the reflected light signals (Sr2) and (Sr3). The arithmetic processing portion (15) identifies a movement direction of a detection object (Obj) on the basis of the phase differences (T21) and (T32). |
