Coincident drop selection, drop separation printing method and system

A drop-on-demand printing system comprising:

• an ink that is attractable;
• and
• a printer having,
• (a) nozzles,
• (b) means for subjecting ink in the nozzles to pressure which is at least momentarily above ambient air pressure to form a meniscus,
• (c) an electrically controlled means for selecting a drop by acting on the meniscus to reduce the surface tension or viscosity of said drop sufficiently so that the meniscus of said selected drop moves, under said pressure, to a different position than the meniscus of unselected drops, and
• (d) drop separation means for projecting the selected drop from the printer to a recording medium.

A printer comprising:

• a plurality of drop-emitter nozzles;
• a body of ink associated with said nozzles;
• a pressurizing device adapted to subject ink in said body of ink to a pressure of at least 2% above ambient pressure, at least during drop selection and separation to form a meniscus with an air/ink interface;
• drop selection apparatus operable upon the air/ink interface to select predetermined nozzles and to generate a difference in meniscus position between ink in selected and non-selected nozzles;
• and
• drop separation apparatus adapted to cause ink from selected nozzles to separate as drops from the body of ink, while allowing ink to be retained in non-selected nozzles.

A printer comprising:

• a plurality of drop-emitter nozzles;
• a body of ink associated with said nozzles, said body of ink forming a meniscus with an air/ink interface at each nozzle;
• drop selection apparatus operable upon the air/ink interface to select predetermined nozzles and to generate a difference in meniscus position between ink in selected and non-selected nozzles;
• and
• drop separation apparatus adapted to cause ink from selected nozzles to separate as drops from the body of ink, while allowing ink to be retained in non-selected nozzles, said drop selection apparatus being capable of producing said difference in meniscus position in the absence of said drop separation apparatus.

A printer comprising:

• a plurality of drop-emitter nozzles;
• a body of ink associated with said nozzles, said body of ink forming a meniscus with an air/ink interface at each nozzle, said ink exhibiting a surface tension decrease of at least 10 mN/m over a 30.degree. C. temperature range;
• drop selection apparatus operable upon the air/ink interface to select predetermined nozzles and to generate a difference in meniscus position between ink in selected and non-selected nozzles;
• and
• drop separation apparatus adapted to cause ink from selected nozzles to separate as drops from the body of ink, while allowing ink to be retained in non-selected nozzles.

A printing method comprising:

• providing a body of ink associated with said nozzles;
• subjecting ink in said body of ink to a pressure of at least 2% above ambient pressure to form a meniscus with an air/ink interface;
• operating upon the air/ink interface of selected nozzles to generate a difference in meniscus position between ink in selected and non-selected nozzles;
• and
• causing ink from selected nozzles to separate as drops from the body of ink, while allowing ink to be retained in non-selected nozzles.

A printing method comprising:

• providing a body of ink associated with said nozzles and forming a meniscus with an air/ink interface at each nozzle;
• operating upon the air/ink interface to select predetermined nozzles and generate a difference in meniscus position between ink in selected and non-selected nozzles;
• and
• causing ink from selected nozzles to separate as drops from the body of ink, while allowing ink to be retained in non-selected nozzles, said drop selecting step being capable of producing said difference in meniscus position in the absence of the step of causing ink to separate from selected nozzles.

A printing method comprising:

• providing a body of ink associated with said nozzles and forming a meniscus with an air/ink interface at each nozzle, said ink exhibiting a surface tension decrease of at least 10 mN/m over a 30.degree. C. temperature range;
• operating upon the air/ink interface to select predetermined nozzles and generate a difference in meniscus position between ink in selected and non-selected nozzles;
• and
• causing ink from selected nozzles to separate as drops from the body of ink, while allowing ink to be retained in non-selected nozzles.