Bar code reader with closed-loop scan beam focusing
AssigneeAllen-Bradley Company, Inc.
InventorRichard J. Huhn
Life of this patent
Estimating the term…
Abstract
A bar code reader including automatic scan beam focusing based upon decoding performance is disclosed herein. The bar code reader includes a focusing lens which is movably supported along the light path of the scanning beam. An electric motor is coupled to the lens support to move the lens relative to the light beam source in response to control signals. The control signals are produced based upon the data error rate for the data produced by the decoding circuit of the reader from the signals produced by the photodetector therein. Based upon the data error rate, the electric motor is controlled to move the lens to focus the light beam and reduce or eliminate the data error.
Claims20
An optical code reader for reading a code located at a distance from the reader, the reader comprising:
- a light source configured to produce a light beam;
- a lens;
- a lens support assembly configured to movably support the lens in the path of the light beam and move the lens in response to movement control signals to produce a focused light beam;
- a scanner configured to cyclically scan the focused light beam over the surface of a code;
- a photodetector configured to produce electrical signals representative of a portion of the focused light beam reflected from the code;
- a decoding circuit coupled to the photodetector, the decoding circuit being configured to convert the electrical signals into digital data, determine the presence of invalid data in the digital data, and produce an error signal in the presence of invalid data;
- and
- a control circuit coupled to the lens support assembly and the decoding circuit, the control circuit applying movement control signals to the assembly based upon the error signal.
An optical code reader for reading a code located at a distance from the reader, the reader comprising:
- a light source configured to produce a light beam;
- a focusing lens;
- a lens support assembly configured to guide the lens in and along the path of the light beam;
- an electric motor operatively coupled to the lens support to move the lens along the path in response to movement control signals to produce a focused light beam;
- a photodetector configured to produce electrical signals representative of the light reflected thereon;
- a pair of oscillating mirrors located in the path to cyclically scan the focused light beam over a two-dimension area within which the code may reside, and direct a portion of the focused light beam reflected from the code to the photodetector;
- a decoding circuit coupled to the photodetector, the decoding circuit being configured to convert the electrical signals into digital data, determine the presence of data errors in the digital data, and produce an error signal in the presence of data errors;
- and
- a control circuit coupled to the electric motor and the decoding circuit, the control circuit applying movement control signals to the electric motor based upon the error signal.
An optical code reader for reading a code, the reader comprising:
- light means for producing a light beam;
- focusing means for focusing the light beam;
- movement means for movably supporting the focusing means in the path of the light beam and moving the focusing means in response to movement control signals to produce a focused light beam;
- means for cyclically scanning the focused light beam over the surface of a code;
- means for producing electrical signals representative of a portion of the focused light beam reflected from the code;
- means for converting the electrical signals into digital data, determining the presence of data errors in the digital data, and applying movement control signals to the movement means based upon the number of data errors.
Dependencies are inferred from the claim text.