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Color Copy Camera Assembly

This project was the mechanical design and packaging of a high resolution color copy camera for use in a teleconferencing projector.  Low cost was achieved by an architecture composed of 2 monochrome CCD units coupled through a polarizing beamsplitter and liquid crystal sequential color filter.  The LC filter also served as one of a pair of crossed polarizers used to remove reflected glare from the copy bed, the other polarizer being applied to the flash assembly supplying illumination to the copy platen.

Because the efficiency of the flash and uniformity of illumination were both critical for this application I designed a reflector with an optically powered surface tailored to compensate for the cosine squared roll off resulting from the approximately point source nature of the flash tube.

Alignment of the camera axis normal to the platen was also important as were centering and rotation so my team and I designed a 5 axis molded plastic stage to compensate for assembly tolerance across the copy stand structure and mitigating the image rectification required in software.  Translations and tilts were by manipulation of PT thread screws acting in opposition to small coil springs.  Once the calibration procedure was completed the setting was locked by injecting epoxy at strategic points in the assembly.  This multipart plastic molded assembly enhanced the performance of the system while reducing manufacturing labor during test and calibration at very low part cost.

© 2019 Donna Kelley

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