Color electrophotographic process, apparatus and recording element useful therein

An electrophotographic process for reproducing a multicolored image pattern of a multicolor original, said process comprising the steps of:

• (a) providing a layered imaging element having a developer-receiving surface and a thickness comprised of at least an insulating layer, a first photoconductive layer sensitive to radiation in a first spectral range, a second photoconductive layer sensitive to radiation in a second spectral range and a conducting layer on the opposite side of said element from said surface, said photoconductive layers and said conductive layer being disposed so as to allow charge migration therebetween;
• (b) applying a uniform electrostatic charge to said element;
• (c) exposing said element to a color image pattern of the original to form a variation in interlayer charge distribution across the thickness of said element in a pattern which corresponds to the color image pattern;
• (d) uniformly flooding said element successively with radiation of said first and second spectral ranges, each such flooding being of an intensity sufficient to discharge portions of said element sensitive to the exposing radiation and create net charge differentials at said developer-receiving surface in an imagewise pattern;
• and
• (e) after each such uniform exposure, electrographically applying a developer having a predetermined subtractive color characteristic to portions of said developer-receiving surface in accordance with said net charge differentials.

A process for producing a multicolored image from a multicolored original comprising the steps of:

• (a) providing a recording element comprising an electrically conducting layer, an electrically insulating layer and at least first and second photoconductive layers sandwiched between said conducting and insulating layers;
• said photoconductive layers and said conductive layer being disposed so as to allow charge migration therebetween, each of said photoconductive layers being sensitive to a different wavelength of the optical spectrum and at least one of said conducting and insulating layers being at least partially transparent to radiation in the optical spectrum;
• (b) uniformly electrostatically charging said insulating layer;
• (c) exposing said recording element, through said transparent layer, to an image radiation pattern representative of said original that comprises wavelengths to which said first and second photoconductive layers are sensitive thereby forming an inter-layer charge distribution pattern which is representative of the original;
• (d) uniformly exposing said recording element through said transparent layer to radiation of wavelength and intensity that will substantially discharge one of said photoconductive layers thereby providing a first surface charge pattern on said element;
• (e) applying marking particles having a first subtractive color characteristic to said insulating layer while establishing across said element and said first toner an electrical field of a first potential;
• (f) uniformly exposing said recording element through said transparent layer to radiation of wavelength and intensity that will substantially discharge at least the other of said photoconductive layers thereby providing a second surface charge pattern on said element;
• and
• (g) applying marking particles having a second subtractive color characteristic to said insulating layer while establishing across said element and said second toner an electrical field of a second potential whereby a multicolored self-registered particle image of said original is formed on said insulative layer.

A process for producing a multicolored image from a multicolored original comprising the steps of:

• (a) providing a recording element having an imaging surface and including a first photoconductive layer sensitive substantially only to light in a first wavelength range, a second photoconductive layer sensitive substantially only to light in a second wavelength range and an electrically insulating layer, said photoconductive layers being disposed so as to allow charge migration therebetween and one of said photoconductive layers being adapted for electrical contact with an electrically conductive surface;
• (b) uniformly electrostatically charging said imaging surface of said recording element;
• (c) in the presence of an electrical field, imagewise exposing said recording element to a light pattern corresponding to the multicolored original, thereby forming, within said element, a pattern of inter-layer charge distribution that is representative of the color information on the original;
• (d) uniformly exposing said recording element to light of wavelength and intensity selected to substantially discharge one of said photoconductive layers and provide a first image charge pattern on said imaging surface;
• (e) applying marking particles of a first subtractive color characteristic to said imaging surface in the presence of a first biasing electrical potential to produce a first particle image on said imaging surface in accordance with said first image charge pattern;
• (f) uniformly exposing said recording element to light of wavelength an intensity selected to substantially discharge at least the other of said photoconductive layers and provide a second image charge pattern on said imaging surface;
• and
• (g) applying marking particles of a second subtractive color characteristic to said imaging surface in the presence of a second biasing electrical potential to produce a second particle image on said imaging surface which is superimposed on said first particle image in accordance with said second image charge pattern.

A process for producing a multicolored image from a multicolored original comprising the steps of:

• (a) providing a recording element having an imaging surface and including (1) an electrically conducting layer, (2) a first photoconductive layer sensitive to light of a first color, (3) a second photoconductive layer sensitive to light of a second color, (4) a third photoconductive layer sensitive to light of a third color and (5) an electrically insulating layer, said photoconductive layers and said conducting layer being disposed so as to allow charge migration therebetween and at least one of said conducting and insulating layers being substantially transparent to light in the visible region of the spectrum;
• (b) uniformly electrostatically charging said imaging surface of said recording element;
• (c) imagewise exposing the recording element through said transparent layer to a light pattern comprising said colors and representative of said original, thereby forming in said element an inter-layer charge distribution pattern that is representative of said light pattern;
• (d) uniformly flood exposing said recording element through said transparent layer with light of a color to which at least said first photoconductive layer is sensitive to substantially discharge said first layer and thereby provide a first developable pattern;
• (e) applying marking particles of a first subtractive color characteristic to said imaging surface while establishing a first biasing potential across said layers and said particles to develop said first pattern and produce a first particle image on said surface;
• (f) uniformly flood exposing said recording element through said transparent layer with light of a color to which at least said second photoconductive layer is sensitive to substantially discharge said second layer and thereby provide a second developable pattern;
• (g) applying marking particles of a second subtractive color characteristic to said imaging surface while establishing a second biasing potential across said layers and said particles to develop said second pattern and produce a second particle image on said surface;
• (h) uniformly flood exposing said recording element through said transparent layer with light of a color to which at least said third photoconductive layer is sensitive to substantially discharge said third layer and thereby provide a third developable pattern;
• and
• (i) applying marking particles of a third subtractive color characteristic to said imaging surface while establishing a third biasing potential across said layers and said particles to develop said third pattern and produce a third particle image on said imaging surface;
• whereby a multicolored self-registered particle image of the multicolored original is formed on the imaging surface.