| 摘要 |
<p>PROBLEM TO BE SOLVED: To remove influence of flickering, and perform highly accurate sampling by sampling output of a light sensor in the timing of a sampling waveform in synchronism with an AC frequency measured by a frequency detecting circuit. SOLUTION: An Ac frequency of an AC power source 1 is measured by a frequency detecting circuit 4 connected to the AC power source (a commercial AC power source) 1, and a reference waveform of sampling is formed from the measured AC frequency by a waveform forming circuit 6. A sampling circuit 5 samples output of a light sensor 3 in the timing of this reference waveform. In this case, output of the light sensor 3 shows a waveform changing in a flickering frequency of a light source (a fluorescent lamp) 2, and since the reference waveform of sampling is the same frequency as flickering, when sapling is performed on output of the light sensor in the timing of this sampling waveform, output of a smooth output waveform can be obtained.</p> |
