| 摘要 |
PURPOSE:To obtain a suitable slice level, by interpolating a rapid signal level change, in determining the slice level by an envelope. CONSTITUTION:A light spot is irradiated on a printed where an electrode pattern is formed, the transmitted light is received at a photodetector 1 to obtain an electric signal corresponding to the electrode pattern. This signal is in A/D conversion and inputted to a shift register 3. Interpolation circuits 9a, 9b calculate the level value between two points based on the data of points inputted from the shift register 3 and the rate of change of the peak position of the signal. Thus, based on the envelope, a half value of the sum of each value of the envelope is calculated at a slice level circuit 10 and this calculated value is inputted to a comparators 11 as the slice level. |
