| 摘要 |
PURPOSE:To detect degradated degree of an illumination light source to recommend the operator to replace said light source, by comparing the voltage value from a brightness detecting means and the voltage value from a brightness memory circuit with each other to generate alarm. CONSTITUTION:When recording medium A is irradiated by a pair of illumination light sources 1 and 1', reflection lights are focused onto photoelectric conversion element 3 through focusing lens 2. The output of photoelectric conversion element 3 is led to video signal processing circuit 4, and the output signal is led to peak value detecting circuit 5 and is held. Brightness memory circuit 6 stores preliminarily the limit value of brightness of illumination light sources 1 and 1' as a voltage value, and the output of peak value detecting circuit 5 is compared with the output of brightness memory circuit 6 by comparing circuit 7; and if the output of circuit 5 is lower than the voltage value of circuit 6, the output signal of logic ''low'' is input to alarm generating circuit 8 to generate alarm. |
