Method and apparatus for electrically controlling coating layer dimensions

Apparatus for controlling the deposition of coating material on a moving substrate, comprising:

• a coating applicator mounted in a fixed position and adapted for coupling to a source of coating material;
• means for movably supporting a substrate in a spaced relation from said coating applicator to thereby form a coating gap between said applicator and said substrate;
• means for establishing an electrostatic field in said coating gap for charging coating material flowing from said coating applicator and for subsequently transporting said charged coating material to the substrate;
• an electrode assembly including a pair of electrodes mounted in an opposed relation adjacent said coating gap and means for establishing an electrical potential of predetermined magnitude and polarity on each of the electrodes forming said electrode pair, said electrode potential establishing means including means for establishing an electrical potential on each electrode of said electrode pair whose magnitude and/or polarity can be varied independently of one another;
• and
• means for moving the substrate through said coating gap whereby the electric potential on said pair of electrodes interacts with the charged coating material to thereby control the deposition of coating material on the moving substrate.

Apparatus for controlling the width and edge portion thickness of a layer of coating material electrostatically deposited on a moving substrate, comprising:

• an extrusion-type coating applicator mounted in a fixed position and adapted for coupling to a source of coating material, said applicator having an opening therein formed of dielectric material from which coating material flows for substrate coating purposes;
• means for pressurizing coating material within said coating applicator to a pressure level that will maintain a substantially constant volume of coating material at the output of said dielectric applicator opening;
• means for movably supporting a substrate in a spaced relation from said applicator opening output to thereby form a coating gap between said output and said substrate;
• means for applying a vibratory force to coating material at said applicator opening to thereby cause coating material to flow to a selected portion of the output of said applicator opening;
• means for establishing an electrostatic field in said coating gap between coating material at said applicator opening output and a substrate spaced therefrom to charge said coating material and to extract minute coating material particles from coating material at said applicator opening output and subsequently deposit said extracted particles on said substrate;
• an electrode assembly including a pair of electrodes mounted in an opposed relation on opposite sides of said coating gap and means for establishing an electrical potential, of predetermined magnitude and polarity, on each of the electrodes forming said electrode pair;
• and
• means for moving said substrate through said coating gap, at a constant rate, whereby a relatively thin, uniform thickness layer of coating material is deposited on said substrate and whereby the electric potential on each of said electrodes interacts with said charged coating material to thereby cause coating material layer edge portions, of constant thickness, to be deposited along selected paths and thereby produce a coating layer of controlled width on said moving substrate.

A method of controlling the width and edge portion thickness of a layer of coating material electrostatically deposited on a moving substrate, comprising the steps of:

• providing a coating applicator, in a fixed position, adapted for coupling to a source of coating material;
• movably supporting a substrate in a spaced relation from said coating applicator to thereby form a coating gap between said applicator and said substrate;
• establishing an electrostatic field in said coating gap for charging coating material flowing from said coating applicator and for subsequently transporting said charged coating material to said substrate;
• providing an electrode assembly including an electrode mounted adjacent said coating gap and means for establishing an electrical potential, of predetermined magnitude and polarity, on said electrode;
• and
• moving said substrate through said coating gap whereby the electric potential on said electrode interacts with said charged coating material to thereby cause a coating material layer edge portion, of constant thickness, to be deposited along a selected path and thereby produce a coating layer of controlled width on said moving substrate.