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US 4,067,295 AGranted
Magnetic microfield donor system
AssigneeXerox Corporation
InventorsDelmer G. Parker, Lawrence J. Fraser, Joseph L. Scaletta
Life of this patent
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Abstract
A magnetizable donor is magnetized to define a microfield with a characteristic spacing between pole centers of about 0.010 inches. The strong short range fields between poles pick up and hold a thin uniform and continuous layer of magnetic toner. The layer of toner is then electrostatically charged and brought into close proximity to a receptor, without touching the same, where only latent image areas of the receptor attract toner from the donor layer.
Claims4
An apparatus for developing a latent electrostatic image on a receptor member by directing toner material thereto, comprising:
- a magnetically recordable donor member having a path of travel spaced apart from said receptor member by a distance of from about 0.005 to about 0.010 inches;
- means for magnetically recording a multiplicity of magnetic poles on said magnetically recordable donor member, adjacent magnetic poles being spaced apart on the order of about 0.010 inches and of opposite magnetic polarity;
- means for contacting the magnetically recorded donor member with magnetic toner to form thereon an about 1 to about 2 mils thick uniform layer of magnetic toner on said magnetically recorded donor member;
- and means for substantially uniformly maintaining the separation distance of from about 0.005 to about 0.010 inches between said receptor member and said donor member to define a development zone.
1 more element
Dependencies are inferred from the claim text.