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APPARATUS FOR ELECTROSTATIC PRINTING

  • US 3,659,936 A
  • Filed: 01/07/1970
  • Issued: 05/02/1972
  • Est. Priority Date: 01/07/1970
  • Status: Expired due to Term
First Claim
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1. Apparatus for electrostatic printing comprising:

  • a printing plate including a conductive base having a coating of a semiconductor material thereon, said semiconductor material being capable of varying its resistance from a high resistance condition to a low resistance condition in response to energy applied thereto;

    a substantially constant DC voltage source one pole of which is conductively connected to said base for providing a charge which is conducted through said semiconductor material in those areas where said semiconductor is in said low resistance condition;

    writing means for applying energy to selected regions of said coating, in an amount sufficient to vary the resistance of said semiconductor material from said high condition to said low condition to permit passage of said voltage to the surface of said semiconductor material in said selected regions;

    modulating means for varying the amount of energy applied to other regions of said coating to a level which is insufficient for varying the resistance of said semiconductor material in said other regions to said low condition, developing means for applying particles to said printing plate which cling to said coating at said selected regions; and

    transfer means for engaging said printing plate with a record medium to transfer at least a portion of said clinging particles to said record whereby an image of said selected regions is printed on said record.

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