Compact imaging apparatus for a pen-shaped handheld scanner

A compact imaging system is proposed for electronic document input. In this configuration, a linear image sensor formed on a glass substrate is coupled with an optical fiber array plate. There are multiple apertures in each photodiode of this sensor. Light from a linear light emitting diode array is transmitted through the glass, the apertures and the fiber successively and illuminates a document. The scattered light comes back in the same fiber and is detected by the sensitive part of the photodiode. Experiment with a 200dpi sensor shows a good spatial resolution. With a white paper illuminated at 100(mu) W/cm2, a signal yield of 0.75 pC is obtained with 1msec storage time. The depth of field is 70 micrometers . A prototype hand-held scanner has been developed by housing this imaging system in a 10mm-wide pen-shaped speed of 12cm/sec.