Photocopying – Contact printing – Light boxes
Patent
1991-07-08
1992-07-28
Braun, Fred L.
Photocopying
Contact printing
Light boxes
355 71, 355219, 355239, G03G 1502, G03G 2100
Patent
active
051344394
ABSTRACT:
A dual mode electrophotographic print engine. A voltage controller (25) provides operating voltage to a scorotron (27), which applies a charge to a photoreceptive medium. In a first mode a screen (40) is placed in a first position, out of the optical path between the image focusing device and the photoreceptive medium (45). This produces full exposure of the photoreceptive medium (45) to the focused image. This produces a latent image on the photoreceptive medium. Toner is then applied to the latent image to produce a developed image. In the second mode of operation, for producing half-tone copies, the screen (40) is inserted into the optical path. This reduces the exposure of the photoreceptive medium (45). To compensate for the reduced exposure the voltage controller (25) provides a second, lower voltage to the scorotron. This lower voltage compensates for the reduced exposure time so as to produce a high quality latent image. Toner is then applied to the latent image to produce a developed image. The first mode provides for high quality graphic and textual reproduction, whereas the second mode provides for high quality copying of photographs and other pictorial materials.
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Braun Fred L.
Colorocs Corporation
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