Portable bar code scanning device and method

Abstract From the Canadian patent

A compact, portable bar code scanner employing, as a light source a light-emitting diode consumes, extremely low input power. The scanner which, detects the reflectances from bars and spaces of the bar code symbol, uses optical beam-shaping methods to attain a large depth-of-focus for a non-laser system. A shaped illuminating light beam is caused to blink when the symbol is outside the depth-of-focus range and a signature imposed upon the light beam enables the scanner to substantially reject light interference. A scanning version employs an optical assembly mounted upon a bimorph leaf spring that is caused to vibrate at its natural mechanical resonance. The scanner operates with bar code …