US 5,689,291 A · Method and apparatus for producing dot size modulated ink jet printing

Abstract

An ink jet (10, 200) provides high-resolution gray scale printing or switchable resolution printing by providing PZT drive waveforms (100, 110, 120, 360, 370), each having a spectral energy distribution that excites a modal resonance of ink in an ink jet print head orifice (14, 208). By selecting the particular drive waveform with selectable energy inputs that concentrates spectral energy at frequencies associated with a desired oscillation mode and that suppresses energy at the other oscillation modes, an ink drop (170, 180, 190, 210) is ejected that has a diameter proportional to a center excursion size of the selected meniscus surface oscillation mode. The center excursion size of high order oscillation modes is substantially smaller than the orifice diameter, thereby causing ejection of ink drops smaller than the orifice diameter. Conventional orifice manufacturing techniques may be used because a specific orifice diameter is not required. Jetting reliability and contaminant susceptibility are, thereby, improved by eliminating the need for an unconventionally small orifice. Changing a selected PZT drive waveform amplitude changes drop ejection velocity without substantially changing drop volume. This invention, therefore, provides for selection of ejected ink drop volumes having substantially the same ejection velocity over a wide range of drop ejection repetition rates.

Claims25

Dependent claims

In an ink jet printing apparatus, having a transducer and a transducer driver, said transducer coupled to a pressure chamber that is fluidicallly coupled to an orifice in which an ink forms a meniscus and the orifice and an image receiving medium move at selectable scanning speeds relative to one another, and the orifice deposits at a first resolution on the image receiving medium ink dots of a first diameter by moving the orifice and the image receiving medium at a first scanning speed relative to one another and ejecting from the orifice ink drops each having a first volume, an improvement comprising:

the transducer driver generating at least a first and a second selectable energy input that actuates a transducer coupled to the pressure chamber to excite in the meniscus at least respective first and second mode shapes, the at least first and second selectable energy inputs causing ejection of ink drops having respectively at least the first volume and a second volume, the first energy input generated in association with the first scanning speed further having at least a first spectral energy distribution that excites the meniscus in a first mode shape to eject from the orifice ink drops having the first volume;
and
the transducer driver further selecting the second energy input in association with a second scanning speed, the second energy input having at least a second spectral energy distribution that excites the meniscus in a second mode shape to eject from the orifice ink drops having at least a second volume less than the first volume, the second energy input and the second scanning speed cooperating to deposit ink dots of the second diameter on the image receiving medium at a second resolution.

Dependencies are inferred from the claim text.

Method and apparatus for producing dot size modulated ink jet printing

Life of this patent

Method and apparatus for producing dot size modulated ink jet printing

Life of this patent

Abstract

Claims25