Automatic document presence, skew and width detection method and apparatus for a document scanner

A document scanner including a document scan area and having an automatic document presence detection system, said automatic document presence detection system comprising:

• a moving light source having individual pixels extending across one side of said document scan area, said light source directing a strip of light toward said document scan area;
• a light sense means having individual pixels extending across an area corresponding to said light source, said light sense means detecting light emitted from said light source, said light sense means extending outside the strip of light of said light source, such that said light sense means comprises extra pixels relative to said light source;
• a scanner lid, said scanner lid extending across a second side of said document scan area opposing said light source, such that light from said light source that is directed toward said document scan area passes through said document scan area and toward said scanner lid when said scanner lid is shut and a document is not present;
• a means for determining whether said scanner lid is open or shut, such that said document presence system will only monitor for the presence of a document if said scanner lid is shut;
• a light pipe positioned in said scanner lid with a first end at a predetermined position adjacent said document scan area and a second end at a predetermined position outside of said strip of light of said document scan area, said light pipe being so positioned that light directed from said light source toward said document scan area impinges said first end of said light pipe, passes through said light pipe, exits said second end of said light pipe and is directed toward a predetermined number of said extra pixels in said light sense means when a document is not present in said document scan area, and when a document is present in said document scan area light does not pass through said document scan area to said light pipe and said extra pixels in said light sense means;
• and
• a controller for turning on individual pixels of said light source that correspond to the position of said first end of said light pipe at predetermined intervals, said controller being responsive to said extra pixels of said light sense means, whereby if light is detected by said extra pixels of said light sense means the controller continues turning on said light source and monitoring said light sense means at predetermined intervals and if light is not detected by said extra pixels of said light sense means the controller initiates the scanning process.