Laser scanner for reading two dimensional bar codes

An apparatus for detecting indicia including a plurality of groups of elements of different light reflectivity, comprising:

• (a) a light source for emitting a light beam;
• (b) an optical component disposed in the path of said beam for optically modifying and directing the light beam along an optical path toward a target located in the vicinity of a reference plane lying in said optical path so as to scan spatially adjacent elements of groups in said reference plane in a first scan direction;
• (c) sensor means having a field of view operative for detecting light of variable intensity reflected off said target, and for generating an electrical image of said field of view of said sensor means;
• (d) means for storing said electrical image in an addressable storage medium;
• (e) means for performing a linear scan of said electrical image in said addressable storage medium;
• and
• (f) means for changing said linear scan of said electrical image to a different linear scan if a partial but not complete group of elements is recognized by the linear scan of step (e).

A system for reading a bar code symbol, said symbol having at least one row, comprising:

• a hand-held scanning unit in a lightweight, portable housing including
• (i) a light source for generating a light beam directed toward a symbol to be read;
• (ii) means for optically modifying and directing the light beam along an optical path toward said symbol located in the vicinity of a reference plane exteriorly of the scanning trait and for scanning spatially adjacent portions of said reference plane;
• (iii) a photodetector component having a field of view and operative for detecting at least a portion of light of variable intensity reflected off the symbol and for generating electrical signals indicative of the detected intensity;
• (iv) means for converting said electrical signals into digital representations thereof, the digital representations embodying a bit-map image of the field of view of said photodetector component;
• (v) means for storing said digital representations in an addressable storage medium;
• and
• (vi) means for accessing said storage means in an address sequence corresponding to a linear scan through the bit-map image and determining if a row of the bit-map image corresponds to a row of the symbol;
• and
• (vii) means responsive to said determining for automatically changing said accessing to a second address sequence if said linear scan recognizes a partial row of said symbol.

A method for reading a symbol, the symbol comprising at least one recognizable code pattern, comprising the steps of:

• (a) directing a light beam from a light source in a scanning pattern over a symbol to be read;
• (b) detecting at least a portion of light of variable intensity reflected off the symbol over a field of view and generating digital data representative of the detected light intensity;
• (c) transferring the digital data to a memory array such that a digital bitmapped image of the field of view is obtained;
• (d) outputting a portion of the digital bitmapped image data from the memory array in such a manner that a scan of the bitmapped image of at least a portion of a scan line is obtained;
• (e) processing said outputted portion of said digital bitmapped image data to determine if a code pattern of an entire row of a bar code symbol was scanned;
• and
• (f) changing said outputting of a portion of the digital bitmapped image data if it is determined that a code pattern of a partial row of a bar code symbol was obtained in the output from the memory array.

A method of reading a symbol containing light variable elements arranged in multiple rows comprising the steps of:

• (a) directing a light beam across a target area containing said symbol in a pattern sufficient to capture all elements contained in said target area;
• (b) creating an electrical image of reflected light of varying intensity from said target area;
• (c) storing said electrical image in an addressable storage medium;
• (d) processing said electrical image by performing a linear scan of said addressable storage medium in an effort to read said symbol;
• (e) manipulating said linear scan of said addressable storage medium until the entire row of said symbol is recognized;
• and
• (f) continuing the linear scan for which an entire row of said symbol was recognized, until the entire symbol is read.

A method for scanning a bar code symbol having a plurality of discrete groups of information containing elements of different light reflectivity on a target, comprising the steps of:

• (a) directing a light beam in a scanning pattern over a target area containing a symbol to be read;
• (b) detecting reflected light of variable intensity reflected off said target area;
• (c) generating electrical signals indicative of said detected light of variable intensity;
• (d) converting said electrical signals into digital representations thereof, said digital representations comprising a bit map image of said target area;
• (e) storing said digital representations in an addressable storage medium;
• (f) accessing said addressable storage medium in a first address sequence corresponding to a first linear scan through said bit map image;
• (g) processing each pixel in said linear scan to determine the presence in said bit map image of at least a portion of one group of elements of said symbol;
• (h) changing said address sequence to create a different linear scan through said bit map image if less than all of a group of elements of said symbol was determined to be present;
• (i) processing each pixel in said different linear scan to determine the presence in said bit map image of at least a portion of one group of elements of said symbol;
• (j) repeating steps (g) and (h) until an entire group of elements of said symbol is recognized;
• and
• (k) continuing the linear scan for which an entire group of elements of said symbol was recognized.

A method for scanning a bar code symbol having a plurality of rows of data comprising the steps of:

• (a) scanning a light beam over a target area containing a symbol to be read;
• (b) creating a digital representation of reflected light from said target area;
• (c) storing said digital representation in memory;
• (d) accessing said memory in a linear scan;
• (e) determining for each scan line whether a portion of a row of said symbol has been recognized;
• (f) changing said linear scan of said memory to a different scan path if only a portion of a row of said symbol was recognized in step (e);
• (g) repeating steps (d)-(f) until an entire row of said symbol is recognized;
• and
• continuing said linear scan with which an entire row was recognized.