Bar code scanner positioning

A method of reading a two-dimensional bar code symbol, each symbol including a plurality of encoded data characters encoded along the rows of the symbol, using a bar code reader having a scanning head including a scanning light beam generator, and a light detector for receiving light from a symbol being read and for producing electrical signals corresponding to data represented by the symbol, the method comprising:

• (a) positioning the reader relative to an item carrying a symbol to be read, with the scanning light beam arranged to scan across the rows of the symbol;
• (b) moving the reader in a direction about perpendicular to the direction in which information is encoded in the rows;
• (c) determining, from the electrical signals, a relative current row scan rate of the reader with respect to the symbol;
• (d) producing via a dynamically varying relative rate of motion indicator a dynamically varying relative suitability signal representative of the relative suitability of the current rate of motion of the reader;
• and
• (e) adjusting the current relative rate of motion of the reader in dependence upon the dynamically varying relative suitability signal.

A bar code reader for reading two-dimensional bar code symbols, each symbol including a plurality of encoded data characters, said reader being moved by a user in a first of the two bar code dimensions while scanning in a second bar code dimension, said reader comprising:

• a scan head including a laser scanner and a CCD scanner combination for scanning the bar code in the second dimension;
• a light detector for receiving reflected light from the symbol to produce electrical signals corresponding to data represented by the symbol;
• and
• a dynamically varying indicator responsive to the electrical signals and arranged in use to dynamically provide a varying indication to the user during scanning of the relative suitability of a current rate of motion of the reader with respect to the symbol in the first bar code dimension for optimal reading of the symbol.

A bar code reader for reading two-dimensional bar code symbols, each symbol including a plurality of encoded data characters and row indicators, said reader being moved by a user in a first of the two bar code dimensions while scanning in a second bar code dimension, said reader comprising:

• a scan head including a light beam generator for generating a scanning light beam for scanning in the second bar code dimension;
• a light detector for receiving reflected light from the symbol to produce electrical signals corresponding to data represented by the symbol;
• and
• a dynamically varying indicator responsive to the electrical signals and arranged in use to dynamically provide a varying indication to the user during scanning of the relative suitability of a current rate of motion of the reader with respect to the symbol in the first bar code dimension for optimal reading of the symbol based on the information explicitly encoded in the symbol's row indicators.

A bar code reader for reading two-dimensional bar code symbols, each symbol including a plurality of data characters encoded in rows using encoding clusters, said reader being moved by a user in a first of the two bar code dimensions while scanning in a second bar code dimension, said reader comprising:

• a scan head including a light beam generator for generating a scanning light beam for scanning in the second bar code dimension;
• a light detector for receiving reflected light from the symbol to produce electrical signals corresponding to data represented by the symbol;
• and
• a dynamically varying indicator responsive to the electrical signals and arranged in use to dynamically provide a varying indication to the user during scanning of the relative suitability of a current rate of motion of the reader with respect to the symbol in the first bar code dimension for optimal reading of the symbol based on the determination of the cluster changes.