Monolithic print head structure and a manufacturing process therefor using anisotropic wet etching

A monolithic print head structure for a drop on demand printer, said structure comprising:

• a silicon substrate;
• a silicon dioxide layer formed on a front surface of said substrate:
• a plurality of drop-emitter nozzles including a plurality of nozzle tip hole arrays formed through said silicon dioxide layer, a plurality of ink ingress channels extending from the back surface of said substrate partially therethrough in respective alignments with said nozzle tip hole arrays, and means defining ink passages from the bottom surfaces of said channels through the silicon substrate to respective nozzle tip holes;
• 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 nonselected nozzles.

A monolithic print head structure for a drop on demand printer, said structure comprising:

• a silicon substrate;
• a silicon dioxide layer formed on a front surface of said substrate;
• a plurality of drop-emitter nozzles including a plurality of nozzle tip hole arrays formed through said silicon dioxide layer, a plurality of ink ingress channels extending from the back surface of said substrate partially therethrough in respective alignments with said nozzle tip hole arrays, and means defining ink passages from the bottom surfaces of said channels through the silicon substrate to respective nozzle tip holes;
• 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 monolithic print head structure for a drop on demand printer, said structure comprising:

• a silicon substrate;
• a silicon dioxide layer formed on a front surface of said substrate;
• a plurality of drop-emitter nozzles including a plurality of nozzle tip hole arrays formed through said silicon dioxide layer, a plurality of ink ingress channels extending from the back surface of said substrate partially therethrough in respective alignments with said nozzle tip hole arrays, and means defining ink passages from the bottom surfaces of said channels through the silicon substrate to respective nozzle tip holes;
• a body of ink associated with said nozzles, said body of ink forming a meniscus with an air/ink interface at each nozzle and 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.