Image sensor and optical character reader

An image sensor comprising:

• a frame having an opened top, said opened top including opposing inner tapered sidewalls;
• a first transparent covering mounted in the opened top of said frame with which an original document is brought into contact, said transparent covering including chamfers at top and bottom edges thereof, said top and bottom chamfers having different depths to change the thickness of said first transparent covering above said opened top of said frame, along the light receiving axis of said image sensor, thereby changing a focal length from a top of said first transparent covering to a light receiver when said first transparent covering is mounted on the opposing inner tapered sidewalls of said frame;
• a platen roller for moving an original document onto said first transparent covering;
• a light emitter for irradiating light onto the original document;
• and
• an optical system for condensing light reflected by the original document;
• said light receiver receiving the condensed light from said optical system.

An optical character reader comprising:

• an image sensor including,
• a frame having an opened top, said opened top including opposing inner tapered sidewalls;
• a first transparent covering mounted in the opened top of said frame with which an original document is brought into contact, said transparent covering including chamfers at top and bottom edges thereof, said top and bottom chamfers having different depths to change the thickness of said transparent covering above the top portion of said frame, along the light receiving axis of said image sensor, thereby changing a focal length from a top of said first transparent covering to a light receiver when said first transparent covering is mounted on the opposing inner tapered sidewalls of said frame;
• a platen roller for moving an original document onto said first transparent covering;
• a light emitter for irradiating light onto the original document;
• and
• an optical system for condensing light reflected by the original document;
• said light receiver receiving the condensed light from said optical system.

An optical character reader comprising:

• an image sensor, including,
• a frame, including an opening, for housing said image sensor;
• optical means for irradiating light on and receiving light reflected by a document;
• focal length changing means, including a transparent covering, for changing a focal length formed by said frame and said optical means by changing a thickness of said transparent covering above a top portion of said frame, alone a light receiving axis of said image sensor.