Portable bar code scanning device and method
AssigneeNuma Corporation
InventorRichard E. Williams
Life of this patent
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Abstract
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 symbols responsive to red light and is of sufficiently low weight to be easily hand-held.
Claims12
A device for measuring at a variable throw distance the reflectance of a zone in a bar code symbol, comprising:
- a housing normally supportable by a user at said variable throw distance from said symbol;
- an optical assembly attached to said housing by coupling means;
- a light-emitting diode affixed to said assembly for providing a radiant light beam of constant average energy;
- optical condensing means affixed to said assembly for directing said radiant light beam to intersect said zone;
- telescope means affixed to said assembly and having a field-of-view falling within the intersection of said radiant beam and said zone:
- and
- sensor means affixed to said telescope means for detecting the intensity of reflected light within said field-of-view and for generating an electrical signal indicative of said intensity, whereby said signal characterizes said measurement.
A method for indicating at a distance the reflectance of a zone in a bar code symbol comprising the steps of:
- irradiating an area of said symbol encompassing said zone with a predetermined-energy radiant light beam;
- shaping said beam to force its cross-section area transverse to distance to vary substantially inversely with distance;
- and
- detecting at said distance through a fixed aperture the reflected light within a substantially constant field-of-view contained within said zone, whereby the detected amplitude is indicative of said reflectance.
A device for characterizing at a distance the reflectance of a zone in a bar code symbol comprising:
- a housing positioned said distance from said symbol;
- an optical assembly attached to said housing by coupling means;
- a light-emitting diode affixed to said assembly to provide a radiant light beam of constant average energy;
- beam controlling means to shape said beam's cross-section area transverse to distance to vary substantially inversely with said distance, and to direct said beam to irradiate on area of said symbol that encompasses said zone;
- telescope means having a fixed aperture stop and a field-of-view falling within said zone;
- and
- detector means affixed to said telescope means for detecting the intensity of reflected light within said field-of-view and for generating an electrical signal indicative of said intensity, whereby said signal characterizes said reflectance.
Dependencies are inferred from the claim text.