Apparatus for point-by-point reading of documents using photodetector matrix

In an apparatus for the point-by-point reading of a document including:

• (a) a matrix of photodetector elements, said matrix comprising p groups of q basic elements aligned along a first axis, each of said basic elements having an input terminal and an output terminal;
• (b) a circuit having p connections, each of said connections being connected to the input terminal of each of the q basic elements in a corresponding one of said p groups;
• and
• (c) an output circuit having q connections, each of said connections being connected to the output terminal of each of the basic elements occupying a corresponding position within said p groups,
• each of said basic elements comprising a photodiode and an associated diode which is insensitive to light radiation, said photodiodes and associated diodes each having a first electrode of one polarity and a second electrode of opposite polarity, said first electrode of each photodiode being connected to said first electrode of said associated diode, said second electrode of each photodiode serving as the output terminal of a corresponding one of said basic elements, and said second electrode of each associated diode serving as the input terminal of said corresponding one of said basic elements, said circuit comprising a shift register for supplying a polarization voltage pulse to each of said p connections in sequence in order to render the basic elements connected thereto conductive, the improvement wherein in each basic element the arrangement of layers of material in the interelectrode space of said photodiode is the same as the arrangement of layers of material in the interelectrode space of said associated diode.