| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a lighting monitoring method for a discharge tube capable of accurately detecting the lighting state of a discharge tube, and to provide a lighting monitoring device with a simple circuit configuration and simple wiring and capable of performing the lighting monitoring method. <P>SOLUTION: The lighting monitoring device 10 comprises a first zero cross detecting circuit 24 and a second zero cross detecting circuit 30 which are connected with a lighting circuit 100 through band pass filters 22, 28. When a rising zero cross of a current waveform is detected by the first zero cross detecting circuit 24, a zero-clear signal for carrying out the zero clear of a counter 34 counting a clock signal of a clock circuit 32 is sent to a counter 34. The clock signal is counted by the zero cleared counter 34, a falling zero cross of a voltage waveform is detected by the second zero cross detecting circuit 30, and count data are latched by a sent latch signal. The phase difference of the current waveform and the voltage waveform is detected from the latch data, and the lighting state of a sodium lamp is grasped. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
