Flat bed scanner system and method

Abstract

A flat bed scanner system for optically sensing a transparent original image and producing three channels of binary digital data representing the densities of the original image. Each channel produces data in response to one sensing color and sensing of the original image occurs by directing a focused image of a beam of white light onto and across the original image in a pattern of parallel scan lines there being a plurality of sensing positions along each scan line, and producing the digital output data in response to the modulated beam of light transmitted by the original image. There is an optical system which provides for the directing of the beam of white light across the original image and which directs the modulated beam onto sensors. The optical system includes color correction and field flattening of the beam of white light and provides a cylinder condenser lens for the modulated beam of white light. An electronic system receives signals from the sensors and converts them into the desired digital data through analog to digital and logarithmic conversion circuits, base line correction circuits and references compensation circuits. The electronic system also provides a sample clock signal synchronizing the locations of the sensing beam with the locations of the sample positions by way of an optical grating system. An electromechanical system is provided to maintain the optical system in focus from scan line to scan line on both the original image and the optical grating system.