| 摘要 |
PROBLEM TO BE SOLVED: To determine a commercial power source frequency in a district area by simple constitution, and to precisely regulate a temperature, in an analyzer provided with a heater for controlling supplied electric power by phase control of commercial alternating current power to regulate the temperature. SOLUTION: A pulse signal is generated in response to the zero cross of a commercial alternating current voltage waveform by a zero-cross detecting circuit 10, a prescribed width of reset pulse is generated after 8.7ms counted from an edge of a zero-cross detecting signal, using a pulse signal generation function incorporated in a PWM control signal generation part 11 used for the phase control. In a flip-flop circuit 12, "H" is read in synchronized with the edge of the zero-cross detecting signal, and an output is "L" all the time because the "L" of a reset input terminal RST has priority when the power source frequency is 50 Hz. The output of the flip-flop circuit 12 is "H" all the time, because a signal level of an output terminal PWM2 is not brought into the "L" in 60 Hz. COPYRIGHT: (C)2005,JPO&NCIPI |
