Electrostatic coating methods and apparatus

Claim 1

THE METHOD OF ELECTROSTATICALLY SPRAY COATING A GROUNDED ARTICLE SURFACE PORTION OF SUBSTANTIAL AREA WITH COMPRISES CREATING AN ELECTROSTATIC DEPOSITNG FIELD HAVING SAID SURFACE PORTION AS ONE TERMINUS WITH THE LINES OF FORCE DISTRIBUTED THEREOVER, THE DEPOSITING FIELD AT ITS OTHER TERMINUS HAVING SUBSTANTIALLY ALL OF THE LINES OF FORCE FROM SAID SURFACE PORTION CONCENTRATED AT A SINGLE SHARP ELECTRODE TIP FACING TOWARD THE ARTICLE, SAID ELECTRODE BEING NEGATIVE WITH RESPECT TO SAID ARTICLE AND THE ELECTROSTATIC FIELD AT SAID ELECTRODE TIP HAVING AN AVERAGE PORTENTIAL GRADIENT AT LEAST OF THE ORDER OF 5,000 VOLTS PER INCH PROVIDING A HIGHLY IONIZED ZONE IMMEDIATELY ADJACENT SAID ELECTRODE TIP, ATOMIZING COATING MATERIAL ISSUED AS A SOLID LIQUID STREAM FROM A SMALL ORIFICE BY INTERACTION WITH AIR INTO A SPRAY OF FINE COATING MATERIAL PARTICLES PROJECTED TOWARD THE ARTICLE FROM A LOCATION MORE REMOTE FROM THE ARTICLE THAN SAID ELECTRODE TIP AND WITH THE AXIS OF THE SPRAY PATTERN NEAR SAID TIP, AND SHAPING THE SPRAY PATTERN BY AIR ISSUING FROM ANOTHER ORIFICE IN A MEMBER SO CONSTRUCTED AND LOCATED RELATIVE TO THE ELECTRODE TIP AS NOT TO DETRACT FROM THE HIGH FIELD CONCENTRATION THEREAT, THE FIELD CREATING CONNECTION TO SAID ELECTRODE BEING COMPLETED THROUGH A RESISTOR OF AT LEAST ABOUT ONE MEGOHM PER KILOVOLT OF A HIGH POTENTIAL SOURCE, THE ZONE OF ATOMIZATION BEING SO LOCATED RELATIVE TO THE ELECTRODE TIP THAT THE PARTICLES ARE PROJECTED IN PATHS GENERALLY COINCIDING WITH THOSE OF THE LINES OF FORCE EXTENDING FROM SAID ELECTRODE TIP TO SAID SURFACE PORTION, SAID SPRAY PARTICLES HAVING VELOCITIES NOT IN EXCESS OF ABOUT 3,000 FEET PER MINUTE ADJACENT SAID SURFACE, THE DISTANCE OF THE ARTICLE FROM THE ELECTRODE TIP BEING SUFFICIENT TO PERMIT DISPERSION OF THE SPRAY PARTICLES AND THE AVERAGE POTENTIAL GRADIENT OF THE CHARGING AND DEPOSITING FIELD EXTENDING FROM SAID ELECTRODE TIP TO THE ARTICLE SURFACE PORTION BEING MATERIALLY GREATER THAN THE AVERAGE POTENTIAL GRADIENT OF ANY OTHER ELECTROSTATIC FIELD EXTENDING TO SAID SURFACE PORTION FROM ANY OTHER POINT WITHIN SAID DEPOSITING FIELD.

Claim 2

THE METHOD OF ELECTROSTATICALLY SPRAY COATING A GROUNDED ARTICLE SURFACE PORTION OF SUBSTANTIAL AREA WITH COMPRISES CREATING AN ELECTROSTATIC DEPOSITNG FIELD HAVING SAID SURFACE PORTION AS ONE TERMINUS WITH THE LINES OF FORCE DISTRIBUTED THEREOVER, THE DEPOSITING FIELD AT ITS OTHER TERMINUS HAVING SUBSTANTIALLY ALL OF THE LINES OF FORCE FROM SAID SURFACE PORTION CONCENTRATED AT A SINGLE SHARP ELECTRODE TIP FACING TOWARD THE ARTICLE, SAID ELECTRODE BEING NEGATIVE WITH RESPECT TO SAID ARTICLE AND THE ELECTROSTATIC FIELD AT SAID ELECTRODE TIP HAVING AN AVERAGE PORTENTIAL GRADIENT AT LEAST OF THE ORDER OF 5,000 VOLTS PER INCH PROVIDING A HIGHLY IONIZED ZONE IMMEDIATELY ADJACENT SAID ELECTRODE TIP, ATOMIZING COATING MATERIAL ISSUED AS A SOLID LIQUID STREAM FROM A SMALL ORIFICE BY INTERACTION WITH AIR INTO A SPRAY OF FINE COATING MATERIAL PARTICLES PROJECTED TOWARD THE ARTICLE FROM A LOCATION MORE REMOTE FROM THE ARTICLE THAN SAID ELECTRODE TIP AND WITH THE AXIS OF THE SPRAY PATTERN NEAR SAID TIP, AND SHAPING THE SPRAY PATTERN BY AIR ISSUING FROM ANOTHER ORIFICE IN A MEMBER SO CONSTRUCTED AND LOCATED RELATIVE TO THE ELECTRODE TIP AS NOT TO DETRACT FROM THE HIGH FIELD CONCENTRATION THEREAT, THE FIELD CREATING CONNECTION TO SAID ELECTRODE BEING COMPLETED THROUGH A RESISTOR OF AT LEAST ABOUT ONE MEGOHM PER KILOVOLT OF A HIGH POTENTIAL SOURCE, THE ZONE OF ATOMIZATION BEING SO LOCATED RELATIVE TO THE ELECTRODE TIP THAT THE PARTICLES ARE PROJECTED IN PATHS GENERALLY COINCIDING WITH THOSE OF THE LINES OF FORCE EXTENDING FROM SAID ELECTRODE TIP TO SAID SURFACE PORTION, SAID SPRAY PARTICLES HAVING VELOCITIES NOT IN EXCESS OF ABOUT 3,000 FEET PER MINUTE ADJACENT SAID SURFACE, THE DISTANCE OF THE ARTICLE FROM THE ELECTRODE TIP BEING SUFFICIENT TO PERMIT DISPERSION OF THE SPRAY PARTICLES AND THE AVERAGE POTENTIAL GRADIENT OF THE CHARGING AND DEPOSITING FIELD EXTENDING FROM SAID ELECTRODE TIP TO THE ARTICLE SURFACE PORTION BEING MATERIALLY GREATER THAN THE AVERAGE POTENTIAL GRADIENT OF ANY OTHER ELECTROSTATIC FIELD EXTENDING TO SAID SURFACE PORTION FROM ANY OTHER POINT WITHIN SAID DEPOSITING FIELD.