| 摘要 |
PURPOSE:To simply check a marker detection state, by stopping a web while detecting a marker and by altering the light detection threshold value of a light detection circuit to diagnose and control the detection state and indicate it and thereafter setting the original threshold value again. CONSTITUTION:The positive input terminal of a comparator 15 is connected to a power voltage +5V through a series circuit comprising a diode D1 and a resistor R5 and another series circuit comprising a diode D2and a resistor R6. Test signals 1, 2 are applied to the connection node between the diode D1 and the resistor R5 and that between the diode D2 and the resistor R6 through TTL open colector inverter 21, 22. |
