Signal processing apparatus and method, and displacement detecting apparatus using the same

A signal processing method, comprising steps for:

• the reception of original two-phase signals each having the possibility of amplitude fluctuation;
• the formation of new two-phase signals from said received original two-phase signals, the formation of said new two-phase signals being executed by the parallel formation of intermediate stage two-phase signals and a phase component eliminated signal having the phase components of said original signals eliminated therefrom from said original two-phase signals, and the eliminating process of the fluctuation component of amplitude by the offsetting process of respective ones of said intermediate stage two-phase signals and said phase component eliminated signal, said new two-phase signals having a predetermined phase relation with said original two-phase signals;
• and
• the output of said new two-phase signals.

A displacement detecting apparatus, comprising:

• a sensor portion for outputting the displacement of a movable portion as two-phase signals corresponding to said displacement;
• and
• a signal processing portion for forming new two-phase signals from the two-phase signals from said sensor portion, said signal processing portion forming intermediate stage two-phase signals from the two-phase signals from said sensor portion and a signal having the phase component of an original signal eliminated therefrom in parallel, and dividing respective ones of said intermediate stage two-phase signals and said phase component eliminated signal to thereby eliminate the fluctuation component of amplitude and form said new two-phase signals, said new two-phase signals having a predetermined phase relation with the two-phase signals from said sensor portion,
• the displacement information of said movable portion being detected by said new two-phase signals.