Electrophotographic reproduction apparatus and method with selective screening

In an electrophotographic reproduction apparatus for reproducing an original document sheet having a continuous tone image on a portion thereof wherein the image is to be reproduced as a halftone reproduction, the apparatus including means for supporting the original document sheet at an exposure station, means including a photoconductive member for forming a developable electrostatic latent image when subjected to imaging radiation from the original document sheet;

• means for illuminating the original document sheet and for imaging light from the original document sheet onto an area of the photoconductive member;
• and the improvement which comprises:
• first means providing signals related to the position of the continuous tone image area relative to a reference element on the original document sheet;
• and
• programmable second means responsive to said signals for forming a developable electrostatic latent halftone pattern image on the portion of the area of the photoconductive member which is to form the reproduction of the continuous tone image area.

In a method for making electrophotographic reproductions, the method including the steps of providing from a first source light modulated with image information onto an electrostatically charged photoconductive member to form a developable electrostatic latent image of the image information on an area of the photoconductive member;

• and the improvement which comprises:
• (a) providing signals related to the position of an image area to be screened relative to a reference element;
• and
• (b) forming in response to said signals an electrostatic latent halftone pattern image using a source independent of the first source on the portion of the area of the photoconductive member which is to form the reproduction of the image information to be screened.

In an apparatus for making electrophotographic reproductions from an electrostatically charged photoconductive member for forming a developable electrostatic latent image when subjected to imaging radiation;

• first means for exposing an area of the photoconductive member with light modulated with image information;
• and the improvement which comprises:
• means providing signals related to the position of an image area to be screened relative to a reference element;
• and
• second means independent of the first means and responsive to said signals for forming a developable electrostatic latent halftone pattern image on the portion of the area of the photoconductive member which is to form the reproduction of the image information.

In a method for electrophotographically reproducing an original document sheet having a multicolor continuous tone image on an area portion thereof within the image is to be reproduced as a halftone reproduction, the method including the steps of supporting the original document sheet at an exposure station, repeatedly illuminating the original document sheet, imaging light reflected from or transmitted through the original documet sheet onto a photoconductive member to form a plurality of developable electrostatic latent color-separation images of the document sheet on different image frames of the photoconductive member;

• and the improvement which comprises:
• (a) providing signals related to the position of the continuous tone image area relative to a reference element on the original document sheet;
• and
• (b) forming in response to said signals electrostatic latent halftone-pattern color separation images on the portions of the image frames which are to form the reproductions of the continuous tone image area.

In a method for electrophotographically reproducing an original document having a continuous tone image on an area thereof, wherein the image is to be reproduced as a halftone reproduction, the method including the steps of supporting the original document at an exposure station, illuminating the original document, imaging light reflected from or transmitted through the original document onto a photoconductive member to form a developable electrostatic latent image of the document on a predetermined area of the photoconductive member;

• developing the developable image and the improvement which comprises:
• automatically sensing the relative position(s) of areas of continuous tone information on the document and generating signals relative thereto;
• and
• forming in response to said signals an electrostatic latent halftone pattern image on the portion(s) of the predetermined area(s) which is (are) to form the reproduction(s) of the continuous tone image area(s).

In a method for electrophotographically reproducing an original document sheet having both a continuous tone image information content on an area thereof and image information content of another kind that is of non-continuous tone such as line-type information, the method including the steps of:

• a. illuminating the original document sheet;
• b. exposing a photoconductive member having a uniform electrostatic charge thereon to light reflected from or transmitted through the original document sheet to form a developable latent electrostatic image of the information on the document sheet;
• c. exposing the photoconductive member to light modulated by a halftone screen pattern before, during or subsequent to said first exposing step to form a screened latent electrostatic image of the information on the document sheet;
• d. developing the latent electrostatic image, and
• e. transferring the developed image to a copy sheet, the improvement which comprises:
• the step of automatically sensing the relative position(s) of areas of continuous tone information, on the document sheet and generating signals relative thereto and
• wherein in step c., the electrostatic latent image is formed, in response to said signals, with a halftone screen pattern only in those areas which comprise reproductions of continuous tone information found in the original document sheet.

In an electrophotographic reproduction apparatus for reproducing an original document sheet having a continuous tone image on an area thereof wherein the image is to be reproduced as a halftone reproduction, the apparatus including means for supporting the original document sheet at an exposure station, means including a photoconductive member for forming a developable electrostatic latent image when subjected to imaging radiation from the original document sheet;

• means for illuminating the original document sheet and for imaging light from the original document sheet onto a predetermined area of the photoconductive member to form the developable image;
• means for developing the developable image and the improvement which comprises:
• means for automatically sensing the relative positions of areas of continuous tone information on the document sheet and for generating signals relative thereto;
• means responsive to said signals for forming a developable electrostatic latent halftone pattern image on the portion of the predetermined area which is to form the reproduction of the continuous tone image area.