Drop-on-demand method and apparatus using converging nozzles and high viscosity fluids

Claim 3

The method of claim 1 wherein said ink cavity is filled with a marking fluid having a viscosity within the range of from about 20 to about 40 centipoises, said signals for energizing said transducer are produced at a base frequency up to 80 kHz, and said method produces high resolution printing.

Claim 4

The method of claim 1 wherein said nozzle passage has an included or apex angle of about 70 degrees.

Claim 5

Drop-on-demand ink jet printing apparatus comprising a print head having a fluid chamber supplied with a marking fluid, an orifice in fluid communication with the fluid chamber, an electromechanical transducer mounted in mechanical communcation with the fluid chamber, and a series of signals to selectively energize the transducer to eject one drop of the marking fluid from the orifice only when the amplitude of the signal exceeds a predetermined threshold amplitude, characterized in that: said orifice comprises a nozzle passage having an entrance dimension and an exit dimension, the ratio of said entrance dimension to said exit dimension being at least four, thereby producing a nozzle passage which converges strongly toward the exit orifice of the nozzle and in which the effective viscous length of said nozzle passage is short with respect to the physical length of said nozzle passage; said marking fluid has any selected viscosity in the range of 15 to 100 centipoises at the normal operating temperature of said print head; and said series of signals for selectively energizing said electromechanical transducer comprises signals at a base frequency up to 120 kHz, whereby said printing apparatus is capable of operating with a marking fluid at each one of said viscosities throughout the stated range at any given time and with signals at any frequency within the stated range at any given time to produce reliable drop-on-demand printing operation.

Claim 6

Drop-on-demand ink jet printing apparatus comprising a print head having a fluid chamber supplied with a marking fluid, an orifice in fluid communication with the fluid chamber, an electromechanical transducer mounted in mechanical communcation with the fluid chamber, and a series of signals to selectively energize the transducer to eject one drop of the marking fluid from the orifice only when the amplitude of the signal exceeds a predetermined threshold amplitude, characterized in that: said orifice comprises a nozzle passage having an entrance dimension and an exit dimension, the ratio of said entrance dimension to said exit dimension being at least four, thereby producing a nozzle passage which converges strongly toward the exit orifice of the nozzle and in which the effective viscous length of said nozzle passage is short with respect to the physical length of said nozzle passage; said marking fluid has any selected viscosity in the range of 15 to 100 centipoises at the normal operating temperature of said print head; and said series of signals for selectively energizing said electromechanical transducer comprises signals at a base frequency up to 120 kHz, whereby said printing apparatus is capable of operating with a marking fluid at each one of said viscosities throughout the stated range at any given time and with signals at any frequency within the stated range at any given time to produce reliable drop-on-demand printing operation.

Claim 7

The apparatus of claim 4 further characterized in that said marking fluid has a viscosity within the range of from about 20 to about 40 centipoises, said signals are produced at a base frequency up to 80 kHz, and high resolution printing is produced.

Claim 8

The apparatus of claim 4 further characterized in that a plurality of print heads are arranged in an array comprising offset columns and rows and said signals are produced at a base frequency up to 40 kHz so that a line of high resolution printing can be produced as the array is moved relative to a print medium.

Claim 9

The apparatus of claim 1 wherein said nozzle passage has an included or apex angle of about 70 degrees.

Claim 10

The apparatus of claim 7 wherein said nozzle passage is anisotropically etched in a silicn substrate formed from single crystal material oriented with the (100) plane parallel to the major substrate surfaces.