Image reader capable of calculating the real focal length of a p

Details Image reader capable of calculating the real focal length of a p Image reader capable of calculating the real focal length of a p

1988-09-09

1990-05-01

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Photocell controls its own optical systems

355 56, 358497, G01J 120, H04N 140

Patent

active

049220870

ABSTRACT:
An image reader having a mechanism for varying the reading magnification optically by adjusting relative positions of a projection lens and an image sensor is disclosed. The image reader provides a pattern plate on which black or white patterns are formed for detecting a distance defined between two edges of the patterns wherein the distance is read by the image sensor through the projection lens at a predetermined magnification to determined the real focal distance of the projection lens.

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patent: 4728984 (1988-03-01), Daniele
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