Half-tone imaging system
AssigneeXerox Corporation
InventorsRichard M. Bobbe, John A. Durbin, Richard F. Lehman, Frederick A. Seedhouse
Life of this patent
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Abstract
An optical system in which a movable photosensitive member is exposed to a light image of an original document. The optical system includes a light source which illuminates a screen having at least two adjacent spaced rows of opaque dots. Movement of the photosensitive member controls activation of the light source. The light source is activated periodically and responds to the photosensitive member moving a distance corresponding to the distance between adjacent rows of opaque dots on the screen.
Claims9
An optical system for exposing a movable photosensitive member to a light image of an original document, wherein the improvement includes:
- means for sensing the position of the photosensitive member and generating a signal indicative thereof;
- a screen member disposed closely adjacent to the photosensitive member, said screen member comprising a member;
- a first row of dots disposed on said member;
- a second row of dots disposed on said member, said second row of dots being spaced from said first row of dots with each dot of said second row of dots being rotated 90.degree. relative to each row of said first row of dots, and a third row of dots disposed on said member, said third row of dots being spaced from said second row of dots with each dot of said third row of dots being rotated 45.degree. relative to each dot of said second row of dots;
- a screen light source positioned to transmit light rays through said screen member onto the photosensitive member to record thereon a finely divided charge pattern;
- and
- means, responsive to the signal from said sensing means indicating that the photosensitive member moved a distance substantially equal to the distance between two adjacent rows of dots on said screen member, for actuating said screen light source.
An electrophotographic printing machine, including:
- a movable photoconductive member;
- means for charging at least a portion of said photoconductive member to a substantially uniform level;
- means for exposing the charged portion of said photoconductive member to a light image of an original document to record thereon an electrostatic latent image corresponding to the original document;
- means for sensing the position of said photoconductive member and generating a signal indicative thereof;
- a screen member disposed closely adjacent to said photoconductive member, said screen member comprising a member, a first row of dots disposed on said member, a second row of dots disposed on said member, said second row of dots being spaced from said first row of dots with each dot of said second row of dots being rotated 90.degree. relative to each dot of said first row of dots, and a third row of dots disposed on said member, said third row of dots being spaced from said second row of dots with each dot of said third row of dots being rotated 45.degree. relative to each dot of said second row of dots;
- a screen light source positioned to transmit light rays through said screen member onto said photoconductive member to record thereon a finely divided charge pattern;
- and
- means, responsive to the signal from said sensing means indicating that the photoconductive member moved a distance substantially equal to the distance between two adjacent rows of dots on said screen member, for actuating said screen light source.
Dependencies are inferred from the claim text.