Method for controlling the formation of toner images with two distinct toners
AssigneeEastman Kodak Company
InventorRichard G. Allen
Life of this patent
Estimating the term…
Abstract
The process control method for a DAD-CAD image forming method includes forming a DAD electrostatic image of a first polarity and applying toner of the first polarity to form a first toner image and then forming a CAD electrostatic image. To provide ample voltage for formation of the CAD image and to reduce scavenging, the development completion of the first electrostatic image is preferably kept below 0.4, preferably by reducing pole transitions provided by a rotatable magnetic core in toning the first image. The process is further controlled by adjusting an initial charge on the image member which also can be trimmed after formation of the first image by a uniform light exposure and by adjustment of AC biases in both toning steps.
Claims24
An image forming method comprising:
- uniformly charging a photoconductive image member to a charge of a first polarity and a first potential V.sub.0 ;
- imagewise exposing the image member to form a first electrostatic image, said first electrostatic image having a minimum potential V.sub.e ;
- using a first toning station, applying a first toner of the first polarity to the first electrostatic image to form a first toner image of the first polarity in the presence of an electric field controlled by a bias V.sub.b associated with the first toning station, the first toner image having a maximum potential V.sub.d ;
- imagewise exposing the image member to form a second electrostatic image of the first polarity;
- using a second toning station, applying a second toner to the second electrostatic image in the presence of an electric field controlled by a bias V.sub.b ', associated with the second toning station, the second toner being of a second polarity opposite the first polarity, to form a second toner image having a potential at its maximum density of V.sub.d ';
- characterized in that the step of applying a first toner is carried out under conditions providing a development completion of the first toner image equal to less than 0.4, where development completion is equal to ##EQU4##
An image forming method comprising:
- uniformly charging a photoconductive image member to a charge of a first polarity;
- imagewise exposing the image member to form a first electrostatic image;
- applying a first toner of the first polarity to the first electrostatic image to form a first toner image of the first polarity;
- imagewise exposing the image member to form a second electrostatic image of the first polarity;
- applying a second toner to the second electrostatic image, the second toner being of a second polarity opposite the first polarity, to form a second toner image of the second polarity;
- characterized in that said steps of applying first and second toners each include moving a developer of toner and hard magnetic carrier through a development zone while subjecting the developer to a number of magnetic pole transitions per second and wherein the number of pole transitions per second for the step of applying the first toner is substantially less than that for applying the second toner.
Dependencies are inferred from the claim text.