| 摘要 |
PURPOSE:To achieve accurate detection of a transmitted signal with a better noise resistance through reproduction thereof, by a method wherein a video signal of an object to be inspected is converted with a sample holding circuit into an envelope waveform, differentiated after the removal of DC components and transmitted through a pulse transformer. CONSTITUTION:An object 1 to be inspected is picked up with a CCD12 through a lens 11 and a video signal S1 amplified with an amplifier 13 is converted into an envelope waveform with a sample holding circuit 14. Then, after sample hold noises and DC component are removed with a BPF16, a signal S3 containing a square pulse portion is differentiated with a differentiation circuit 18. The differentiated signal S4 is transmitted through pulse transformers 19, and 21 and the signal S5 transmitted is inputted into an operational amplifier 23 of a reproduction circuit 26. Then, a switch SW is turned ON by a clamp pulse S7 from a clamp pulse generation circuit 25 and the inverted integrated signal S5 is clampted at a reference potential. This enables accurate detection of a detection with a better noise resistance.
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