In November 1964 IBM's Advanced Systems Development Division (ASDD) announced the development of an experimental solid state optical scanning device to convert images into electrical signals. Approximately the size of a dime, the Scanistor combined high resolution and quick response with other attributes of solid state electronics, such as low power operation, small size and weight, long life and simple circuitry.

Made of silicon and sensitive to both ordinary light and near infrared radiation, IBM's Scanistor test units were tried in such applications as document and film scanning, character recognition and reading punched and mark-sense cards. The ASDD engineers anticipated future uses such as:

Scanistor an experimental solid state optical scanning device to convert images into electrical signals
Shown here is IBM technician Robert J. Lynch, co-inventor of the Scanistor, adjusting the simple circuitry that supplied bias and scanning voltages to the device and differentiated the Scanistor's output to obtain an oscilloscope display of the original text. A card bearing the typed word "Scanistor" had been placed on the rotating drum at the right. Above the drum is a light source that focused an image of the text onto the Scanistor.

The Scanistor provided on a single output wire an analog voltage that represented both the amount and position of light shining on its surface. Or, with different operating voltages, the Scanistor could provide a series of corresponding electrical pulses for entry into a digital computer.

To illustrate one approach to a character recognition application, IBM engineers assembled eight Scanistors into a special pattern to recognize constrained handwriting -- both numbers and letters. For reading, cards on which characters were written were fed into a converted card punch machine which projected each character image onto the Scanistors. Characters were recognized by determining which Scanistors their images intersected.

The experimental Scanistor shown here is one-half inch long, and contains 100 light-sensitive diodes paired with 100 switching diodes. The diode-pairs are spaced 0.005 inch apart to give a resolution of 200 image elements per inch.

The Scanistor was just one of several other handwriting recognition projects undertaken by ASDD in the 1960s. Two months before announcing the Scanistor, the division outlined in a press backgrounder various experiments and scanning techniques dating back to 1962.

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