A grayscale inkjet printing method including the steps of: a) supplying a pigmented inkjet ink to a grayscale print head having nozzles with an outer nozzle surface area smaller than 500 ?m.sup.2 and having an acoustic resonance period ARP of not more than 5.5 ?s; and b) applying a voltage wave form for ejecting pigmented inkjet ink from a nozzle of the grayscale print head within one jetting cycle; wherein the pigmented inkjet ink has a viscosity of at least 3.8 mPa.Math.s at jetting temperature and a shear rate of 1,000 s.sup.?1; wherein the voltage wave form for ejecting the largest ink droplet includes, in chronological order, a first ejecting pulse having an amplitude A1 and a second ejecting pulse having an amplitude A3 with the amplitude A1 complying with the relationship: 0.50?A3<A1<1.40?A3; and wherein a time period between the end time of the first ejecting pulse and the end time of the second ejecting pulse defines an idle time period including no other ejecting pulse, the time period having a duration between 1.5 to 2.5 times the acoustic resonance period ARP; and wherein any non-ejecting pulse having an amplitude A2 present during the idle time period complies with the relationship: A2?0.15?A3. An inkjet printing system is also disclosed.

An acoustic droplet ejection apparatus comprises an acoustic actuator and a fluid well having abase and at least one side wall. The actuator is arranged to couple acoustic energy into the fluid well through the side wall.

Methods of ejecting droplets containing a non-Newtonian fluid by an acoustic droplet ejector can include applying a tone burst of focused acoustic energy to a fluid reservoir containing a non-Newtonian fluid at sufficient amplitude to effect droplet ejection according to a tone burst pattern. The tone burst pattern may include three discrete tone burst segments, the first tone burst segment having greater duration than the second and third segments, and third segment having greater duration than the second segment. The exact durations and amplitudes of the tone burst segments can be tuned to influence the ejection properties.

An inkjet printhead including an inkjet configured to eject drops of ink in response to receiving an electrical signal, a memory configured to store image data, and a processor operatively coupled to the inkjet and the memory. The processor receives the image data and determines a period of latency of the inkjet printhead. When the period of latency is within a predetermined timeframe, the processor increases a voltage of the electrical signal to a second voltage for an initial number of drops to eject the drops of ink in a pattern of printed ink drops with reference to at least a portion of the image data and reduce the voltage of the electrical signal after the initial number of drops to eject drops of ink in a pattern of printed ink drops with reference to a remaining portion of the image data, and generates the electrical signal.

An inkjet printhead including an inkjet configured to eject drops of ink in response to receiving an electrical signal, a memory configured to store image data, and a processor operatively coupled to the inkjet and the memory. The processor receives the image data and determines a period of latency of the inkjet printhead. When the period of latency is within a predetermined timeframe, the processor increases a voltage of the electrical signal to a second voltage for an initial number of drops to eject the drops of ink in a pattern of printed ink drops with reference to at least a portion of the image data and reduce the voltage of the electrical signal after the initial number of drops to eject drops of ink in a pattern of printed ink drops with reference to a remaining portion of the image data, and generates the electrical signal.

Devices and methods are provided for ejecting a droplet from a reservoir using focused acoustic radiation having a plurality of nonsimultaneous and discrete frequency ranges. Such frequency ranges may be used to control droplet volume and/or velocity. Optionally, satellite fluid ejection from the reservoir is suppressed.

An inkjet recording apparatus 100 which records on a transferred recording medium X by an inkjet scheme, wherein the inkjet recording apparatus 100 includes guide rolls R for guiding the recording medium X, the recording medium X being negatively charged, recording units 1, 2, 3, and 4 formed of a plurality of recording heads 1a, 2a, 3a, and 4a for spraying ink onto the recording medium X, and a conductive frame unit 11 for supporting the recording heads 1a, 2a, 3a, and 4a, the recording heads 1a, 2a, 3a, and 4a and the conductive frame unit 11 having a continuity relation and the recording heads 1a, 2a, 3a, and 4a being grounded via the conductive frame unit 11.

An inkjet recording apparatus 100 which records on a transferred recording medium X by an inkjet scheme, wherein the inkjet recording apparatus 100 includes guide rolls R for guiding the recording medium X, the recording medium X being negatively charged, recording units 1, 2, 3, and 4 formed of a plurality of recording heads 1a, 2a, 3a, and 4a for spraying ink onto the recording medium X, and a conductive frame unit 11 for supporting the recording heads 1a, 2a, 3a, and 4a, the recording heads 1a, 2a, 3a, and 4a and the conductive frame unit 11 having a continuity relation and the recording heads 1a, 2a, 3a, and 4a being grounded via the conductive frame unit 11.

The invention provides apparatuses and methods for acoustically ejecting the fluid from a reservoir contained in or disposed on a substrate. The reservoir has a portion adapted to contain a fluid, and an acoustic radiation generator is positioned in acoustic coupling relationship to the reservoir. Acoustic radiation generated by the acoustic radiation generator is transmitted through at least the portion of the reservoir to an analyzer. The analyzer is capable of determining the energy level of the transmitted acoustic radiation and raising the energy level of subsequent pulses to a level sufficient to eject fluid droplets from the reservoir. The invention is particularly suited for delivering fluid from a plurality of reservoirs in an accurate and efficient manner.

An electronic circuit for driving an individual print element in a print head is disclosed. The print head comprises an array of print elements, each print element having a piezo-electric actuator that is capable of generating an acoustic wave in an ink chamber of the print element, resulting in the ejection of an ink drop out of a nozzle that is in fluid connection with the ink chamber. The electronic circuit comprises a number of analog drivers for amplifying an output current at a voltage level in-between two source voltage levels, wherein the drivers can be switched into a tristate condition at a voltage level that does not equal one of the source voltage levels.