in a contact - type image sensor for use in a facsimile equipment or the like , the surface of the sensor is provided with a transparent film which is electroconductive and of which the surface that is in contact with the sensor elements is formed as a roughened surface capable of scattering light . by virtue of the provision of this film , static electricity generated during the running of the original is prevented from causing fluctuations in the sensor output voltage . in addition , light reflected by the surface of the transparent film is prevented from becoming directly incident on the sensor elements and , hence , from causing abnormal increases in the sensor output .