| 摘要 |
PURPOSE:To automatically set an appropriate slicing level by optimally amplifying outputs of individual photoelectric elements with synchronous driving of a plurality of light sources facing opposite to each other and said elements. CONSTITUTION:While no sheet paper is between photoelectric conversion elements 1 and light emitting elements 2, two selectors 3 are switched in the range of Kl-Kn. Outputs of the number n of photoelectric conversion elements 1 are amplified sequentially with an amplifier 4, digitally converted with an A/D converter 6 and taken into a microcomputer 8 as data. Based on this data information, simultaneously with the time-sharing switching of the selector 3, an automatic gain control circuit AGC5 switches the amplification gain for each detector to maintain the output of the amplifier 4 for n sets of Kl-Kn. A slice level is previously set for each of Kl-Kn. This enables detection of the existence of the sheet paper between the photoelectric conversion elements 1 and the light emitting elements 2. |
