Tektronix, Inc.

Douglas M Stanley

Joy Roy

James D Buehler

Ronald L Adams

Howard V Goetz

Jeffrey J Anderson

Nasser Alavizadeh

Susan C Schoening

Bryan F Johnson

A multiple-orifice phase-change ink-jet print head (28, 44) is heated by a composite laminate heater (29, 58) having multiple heating zones (31-31K, Z1-Z28) spanning the X- and Y-directions of the print head. The print head has multiple rows of ink-jet orifices (34, 46) spread across its face in the Y-direction with the ink in each orifice in each row requiring substantially the same temperature to ensure a uniform jetting velocity from every orifice. In one embodiment, the print head is in fluid communication with a thermally massive multicolor ink reservoir (52) that conducts heat through a region of contact (92) with the print head. A rotating drum (32), spaced across a gap (90) from the print head, draws air through the gap thereby cooling the print head differentially in the Y-direction. Radiation and convection are further thermal transfer mechanisms that contribute to a nonuniform temperature throughout the print heads. The heating zones of the print head heaters compensate for the various thermal transfer mechanisms to cause a uniform temperature throughout the print heads. A temperature controller ( 16) requires only a single temperature sensor (18, 104) to regulate print head temperature.

Apparatus and method for heating ink to a uniform temperature in a

A drop-on-demand ink jet print head (9) has an ink pressure chamber (22) coupled to a source of ink (11) and an ink drop ejecting orifice (103) with an ink drop ejection orifice outlet (14). An acoustic driver (36), in response to a drive signal (100), produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop ejecting orifice (103) and the ink jet ejection orifice outlet (14) of the ink jet print head (9). In accordance with the present invention, controlling the operation of the ink jet print head (9) with a particular drive signal reduces print quality degradation resulting from rectified diffusion, which is the growth of .air bubbles dissolved in the ink from the repeated application of pressure pulses to the ink residing within the ink pressure chamber (22) of the ink jet print head (9), such pressure pulses causing the application of pressures below ambient pressure. This method of controlling the operation of the ink jet print head (9) applies pressure below ambient pressure to the ink residing within the ink pressure chamber (22) of the ink jet print head (9) at magnitudes less than the threshold pressure magnitude that leads to the air bubble growth.

Method of operating an ink jet to reduce print quality degradation

A multi-orifice ink jet print head array (32) includes multiple drive circuits that drive respective PZTs (16) to cause ink drops to be ejected from respective orifices (28). Each drive circuit includes a voltage divider (36) having a resistor R.sub.S. The ink drop ejection velocity is controlled by selecting an appropriate value of R.sub.S for each voltage divider, thereby compensating for imperfections in manufacturing of the print head array. The value of a particular R.sub.S is selected by temporarily connecting the corresponding voltage divider (36A), in which the value of R.sub.S is R.sub.I, to assessment circuit (56). The assessment circuit includes a potentiometer (66) with resistance value R.sub.POT. Ink drops are ejected at a rapid periodic rate as a camera (102) records the position of the ink drops with respect to a graticule (94) at the time a strobe (100) flashes. The value of R.sub.POT is adjusted until the ink drops are on the graticule as viewed on a monitor (108), at which time R.sub.POT =R.sub.T. R.sub.S is then laser trimmed by an amount R.sub.T, so that R.sub.S =R.sub.F, where R.sub.F =R.sub.I +R.sub.T.

Array jet velocity normalization

A drop-on-demand ink jet has an ink chamber coupled to a source of ink, and an ink drop orifice with an outlet. An acoustic driver produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop orifice and outlet. The driver is driven with bipolar drive pulses having a refill pulse component and an eject pulse component of a polarity which is opposite to the refull pulse component. The refill and eject pulse components are separated by a wait period. The drive pulses may be adjusted to minimize their energy content at a frequency corresponding to the dominant acoustic resonance frequency of the ink jet. This will accelerate drop breakoff, optimize drop shape and minimize drop speed variations over the range of drop printing rates. The ink jet printer of the present invention may be used to print with a wide variety of inks, including phase change inks to achieve high print quality at high print rates.

Method of operating an ink jet to achieve high print quality and high

A drop-on-demand ink jet print head (9) has an ink pressure chamber (22) coupled to a source of ink (11) and an ink drop ejecting orifice (103) with an ink drop ejection orifice outlet (14). An acoustic driver (36), in response to a driver signal (100), produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop ejecting orifice (103) and the ink jet ejection orifice outlet (14) of the ink jet print head (9). In accordance with the present invention, controlling the operation of the ink jet print head (9) with a particular drive signal reduces print quality degradation resulting from rectified diffusion, which is the growth of air bubbles dissolved in the ink from the repeated application of pressure pulses to the ink residing within the ink pressure chamber (22) of the ink jet print head (9), such pressure pulses causing the application of pressures below ambient pressure. This method of controlling the operation of the ink jet print head (9) applies pressure below ambient pressure to the ink residing within the ink pressure chamber (22) of the ink jet print head (9) at magnitudes less than the threshold pressure magnitude that leads to the air bubble growth.

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Tigard, OR, United States of America

Douglas M Stanley