To provide an AC signal phase detecting arrangement of low cost which does not require expensive transformer for insulation.
The voltage of an AC power supply 7 is converted into a rectangular form wave by a photocoupler 10 and is inverted at an inversion circuit 14 to be an output Out1, which is inputted in an AND circuit 15 and a shift register 18. The output Out1 is further inverted and inputted in an AND circuit 16; and a pulse signal A of cycle 2T is inputted in the AND circuit 15 while a pulse signal B of a cycle T is inputted in the AND circuit 16, from a pulse signal generating circuit (not shown). The outputs of the AND circuits 15 and 16 are inputted in a clock terminal of the shift resistor 18 via an OR circuit 17, and the output Out1 of the inversion circuit 14 is supplied to a data terminal. When the output Out1 goes into high level, it is fetched in the shift register 18 at the cycle 2T; and since it is compressed to half of that fetched at the cycle T, and the rise point of the output of the shift register 18 is a center point, the phase is found from this center point.
Masuo Oiwa
Takenaka Ikuo
Keigo Murakami
Next Patent: TRANSMISSION LINE ANALYTICAL METHOD