Analog-to-digital converter with automatic range and sensitivity adjustment
First Claim
1. A bar code reading apparatus for reading decodable bar code indicia, said bar code reading apparatus comprising:
- an M×
N sensor that senses an excitation carrying information representing an encoded symbol and that provides an analog signal responsive to said excitation at an output terminal;
an analog-to-digital converter configured to receive said analog signal from said sensor output terminal at an analog data input terminal, and to provide optimized digital data in an N-bit representation, where N is a positive integer greater than 1, said analog-to-digital converter being controlled so that an N-bit range of said analog-to-digital converter substantially spans a dynamic range of said excitation as sensed by said sensor;
a microprocessor that manipulates said optimized digital data, thereby providing accurate decoding of said digital data under a range of illumination conditions; and
a display capable of displaying an indicia being read.
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Accused Products
Abstract
The invention is a system and method for providing optimized accuracy and precision in analog-to-digital conversions of data. In an embodiment of the invention, an AID converter is configured by setting two separately definable reference voltages that are controlled by a microprocessor. The A/D converter range is as wide as, or slightly greater than, a dynamic range of the analog signal to be converted. The microprocessor adjusts at least one reference voltage. The A/D converter receives analog signals from a sensor. The dynamic range of the signal from the sensor, or the sensor operating conditions, are used to define the reference voltages. The converted data is provided to a data processor at a rate controlled by a clocking signal. In a method according to the invention, the A/D converter is operated using the features described above. The accuracy and the precision of the converted data are thereby optimized.
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Citations
20 Claims
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1. A bar code reading apparatus for reading decodable bar code indicia, said bar code reading apparatus comprising:
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an M×
N sensor that senses an excitation carrying information representing an encoded symbol and that provides an analog signal responsive to said excitation at an output terminal;
an analog-to-digital converter configured to receive said analog signal from said sensor output terminal at an analog data input terminal, and to provide optimized digital data in an N-bit representation, where N is a positive integer greater than 1, said analog-to-digital converter being controlled so that an N-bit range of said analog-to-digital converter substantially spans a dynamic range of said excitation as sensed by said sensor;
a microprocessor that manipulates said optimized digital data, thereby providing accurate decoding of said digital data under a range of illumination conditions; and
a display capable of displaying an indicia being read. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification