Photocopying – Projection printing and copying cameras – Combined with or convertible to a contact printer
Patent
1983-11-09
1985-09-03
Prescott, A. C.
Photocopying
Projection printing and copying cameras
Combined with or convertible to a contact printer
355 3CH, 355 14E, 355 15, 118652, G03G 1500
Patent
active
045389004
ABSTRACT:
This apparatus relates particularly to apparatus and method for conditioning and pre-fatiguing a photoconductive drum in an electrophotographic copying apparatus. In a preferred embodiment, a two color LED is located adjacent the photoconductive surface. The color of the emissions from these two-color LED's is controlled through the polarity of the voltage applied to the terminals; that is, reversal of the polarity of the voltage applied reverses the color displayed. Therefore, in a preferred embodiment of the present invention, means are provided for supplying an AC driving current to the LED which would inherently result in a synchronous high speed flashing of the red/green light. By combining this AC source with a controllable DC bias, it is possible to provide a drum discharge and preconditioning light which is an all red light; an all green light; or which has controllable percentages of red and green in each duty cycle. In an optimum conditioning cycle, when the machine is first turned on a maximum of two cycles of all red light are utilized to build in fatigue; it is thereafter desirable during extended use of the machine to use only green, which will reduce the light fatigue effect on the photoconductive surface. By an appropriate timing circuit, a controllable shift from all red at the beginning of use of the machine through a combined duty cycle combining both red and green to an all green light can be accomplished.
REFERENCES:
patent: 3649262 (1972-03-01), Cade et al.
patent: 3778148 (1973-12-01), Fujitsuka et al.
patent: 3838921 (1974-10-01), Sargis
patent: 4017170 (1977-04-01), Komori et al.
patent: 4244647 (1981-01-01), Fujiwara et al.
Lutus Arthur C.
van Blerk Victor B.
Prescott A. C.
Ricoh & Company, Ltd.
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