| 摘要 |
PURPOSE:To perform sure self-checking and to prevent malfunction, by counting the number of punched signal holes, and discriminating whether film data is read correctly or not from the results of the counting and the signal by the presence or absence of the punching of the signal holes for parity. CONSTITUTION:Cl3 is a constant current source which supplies constant current to a resistor VR. Sliding terminals PM1 and PM2 are provided with the resistor VR, and the potential from the terminal PM1 is kept higher than the potential of the terminal PM2. The terminal PM1 is connected to the inverted input terminal of a comparator AC1 and the terminal PM2 to the inverted input terminal of a comparator AC2. The output of an operational amplifier OA1 is connected to the noninverted input terminal of the comparator AC1 and the output of an operational amplifier OA2 to the noninverted input terminal of the comparator AC2. The period while the output from the comparator AC2 is ''high'' when the two detecting parts for signal holes and sprocket holes detect the sprocket hole simultaneously is made longer than the period while the output from the comparator AC1 is ''High''. |
