US 3,942,080 A · Method and apparatus for applying a uniform electrostatic charge to electrophotographic film

Abstract

Disclosed are apparatus and method for applying a uniform electrostatic charge to an electrophotographic film through use of a corona discharge electrode positioned close to the film, a high voltage AC potential source connected to the electrode and having a potential greater than the corona threshold potential of the electrode, and a high voltage DC potential source connected to the electrode in series with the AC potential source for biasing the AC potential source, the DC potential source voltage being less than the difference between the voltages of the AC potential source and the corona threshold potential of the electrode. The film is subject to a series of first corona discharges of the desired polarity, of which each discharge is alternated with one of a series of second corona discharges having the opposite polarity and of lesser intensity than the first corona discharges.

Claims6

Dependent claims

Apparatus for applying a uniform electrostatic charge to a predetermined portion of an electrophotographic film, comprising:

means for grounding the electrophotographic film;
a lens module having an opening for charging and imaging the film, the opening being formed by a mask which confines charging of the film to the opening area, each area dimension of the opening being larger than one third of the corresponding dimension within the lens module;
a corona discharge electrode positioned within the lens module at a distance from about .2 to about 2.0 inches from the film when the film is placed against the module opening;
a high voltage AC potential source connected to the electrode and having a potential greater than the corona threshold potential of the electrode;
and
a high voltage DC potential source connected to the electrode in series with the AC potential source for biasing the AC potential source, the DC potential source being less than the difference between the voltage of the AC potential source and the corona threshold potential of the electrode.

3 more elements

Dependencies are inferred from the claim text.

Method and apparatus for applying a uniform electrostatic charge to electrophotographic film

Life of this patent

Method and apparatus for applying a uniform electrostatic charge to electrophotographic film

Life of this patent

Abstract

Claims6