Hewlett-packard Company

Gerald L Meyer

Steven L Webb

David W Boyd

Greg A Degi

A system and method for improving the signal to noise ratio of a CCD sensor within an optical scanner varies the exposure time of the CCD sensor. Exposure time is varied by clocking the CCD sensor a number of times equal to the number of pixels in the CCD sensor plus an additional number of clock cycles to create a delay. The additional exposure time maximizes the magnitudes of the charges produced by the CCD sensor. The required delay is computed during a pre-scan calibration step.

System and method for improving the signal to noise ratio of a CCD

The density of pixel samples across a document is determined by employing a constant scanner sensing head sampling rate and driving the scanner head movement at a rate directly correlated to the preselected density level. The scanner operator determines the particular density and introduces a signal to motor drive controls to cause it to move across the image at the preselected rate.

Direction scaling method and apparatus for image scanning resolution

A counter of modulus n counts the oscillations of a variable frequency oscillator whose center frequency is n-times the nominal frequency of digital data having phase variations. The occurrence of a selected value of the count may be taken as a phase corrected clock for the digital data. Differences between successive values in the counter as pulses of the digital data occur indicate shifts in phase thereof, while the modularity prevents absent data pulses from contributing to the phase error. Successive counts are captured, made available as phase error information in digital form, and used to drive a digital-to-analog converter whose output controls the variable frequency oscillator.

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Loveland, CO, United States of America

Gerald L Meyer