Ricoh Company, Ltd.

Ricoh Systems, Inc.

Arthur C Lutus

Victor B Van Blerk

In an electrophotographic copying system designed according to the present invention, a transparent conducting plastic layer is placed between the drum surface and the red/green electroluminescent panel. This layer is either grounded or is biased to repel the electrically charged toner.

Dust control method and apparatus

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.

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Redwood City, CA, United States of America

Arthur C Lutus