| 摘要 |
PURPOSE: A photo mark sensor is provided to obtain a pulse output signal by selectively detecting colors, which are different from a background color and overlapped on the background color, while disregarding the background color of a printing object. CONSTITUTION: A photo mark sensor includes a modulation oscillating circuit section(10) for driving an LED with a predetermined frequency. A band pass filter and an amplifying circuit section(20) are provided to allow a signal having a predetermined frequency band to pass through while amplifying the signal. An integrated circuit section(30) integrates the filtered signal. An on/off output section(40) outputs the integrated signal by comparing the integrated signal with a sensitive adjusting level. An automatic pulse output circuit(50) is provided to selectively detect colors, which are different from a background color. |
