Photoelectric conversion device for use in sensing light reflected from medium surface

A photoelectric conversion device for receiving light reflected from a surface of a medium to be sensed, comprising:

• an insulating substrate;
• a photoelectric conversion layer having a receiving surface to which the light reflected from the surface of the medium to be sensed is supplied, said photoelectric conversion layer being for converting the received light into an electric signal;
• a light shield layer, provided on the insulating substrate, which is made of a first material for shading a portion of the received light passing through the insulating substrate toward a reverse surface of the photoelectric conversion layer so that the portion of received light cannot reach the reverse surface of the photoelectric conversion layer directly;
• an insulating layer provided between the light shield layer and the photoelectric conversion layer;
• a pair of electrodes provided on the photoelectric conversion layer;
• and
• a layer of a second material provided between the photoelectric conversion layer and the pair of the electrodes for ohmic-connecting the electrodes to the photoelectric conversion layer;
• wherein said first material includes one of nonconductive organic high molecular and oxidized metal;
• and
• wherein said device is adapted (a) to have a response time of less than 1.0 msec for each of an on state and an off, and (b) to have a ratio of photocurrent to dark current of greater than 1000.