Optical media monitoring device

An optical media monitoring device that detects presence of light-interrupting media between photoemitter component and a photoreceptor component of a sensor provided to operate in cooperation with each other, the optical media monitoring device comprising:

• means for driving the photoemitter component at a predetermined level of light emission;
• a comparator receiving as one input thereof an output of the photoreceptor component;
• means for generating a reference signal at a predetermined level, the reference signal being input to the other input to said comparator;
• means for controlling said driving means to cause the photoemitter component to emit a level of light lower than a level normally used for media detection;
• and
• means for determining the degree of dust degradation of the sensor by checking, in a state of no media present and the light emission of the photoemitter component reduced by said controlling means, whether the output of the photoreceptor component is greater than the reference signal level.