PROBLEM TO BE SOLVED: To save power consumption of a device and to improve the precision of measurement by making a peak value of a driving current of a light source smaller than that of the conventional one and by making a peak value of a light receiving level of a light-receiving element smaller than that of the conventional one.SOLUTION: Codes of which bits of the Hadamard codes are shifted by the same bit for each code series having the same bit cycle, or codes of which the bits of a PN code are shifted are used as different codes.COPYRIGHT: (C)2009,JPO&INPIT【課題】光源駆動電流の尖頭値を従来のものより小さくし、受光素子の受光レベルの尖頭値を従来のものより小さくして、装置の省電力化を図り、計測精度を向上する。【解決手段】符号として、アダマール符号を同一のビット周期を有する符号系列毎に同じビットだけビット移動した符号、あるいは一つのPN符号をビット移動した符号を異なる符号として用いる。【選択図】図7
