Abstract: A method of selecting a data item from a memory within a first device, the method comprising the steps of evaluating within the first device a function of an input argument so as to form an output value, using the output value to select a data item from the memory and transmitting the selected data item to a second device.

Abstract: A thermal inkjet printer is operated in a spray-mode by deliberately firing ink droplets from a printhead while the meniscus of the remaining ink in the printhead is settling down. Generally, the drops will not travel in a direction perpendicular to the printing surface. By calibrating the printhead, one can determine how many drops are needed to be fired within the boundaries of a pixel to achieve any given optical density. Drops may be fired at rates above 50 kHz, and, depending on the ink, above 70 kHz. Ink with a viscosity of 10 centi-Poise or less, and even 2 centi-Poise or less, may be used. When one is printing both text and non-text images on the same surface, a digital representation of an image to be printed is analyzed and divided into non-text image fields and text fields. Each non-text image field is printed on the printing surface by projecting the corresponding ink droplets in the spray-mode.

Abstract: Selected portions of the orifice plate surfaces are formed to have wetting and non-wetting surface characteristics for minimizing the accumulation of residual ink on the outer surface of the plate and for enhancing the flow of supply ink to the orifices of the plate.

Abstract: An inkjet printhead including a flexible substrate having at least one fold therein such that a first section of the substrate overlies a second section of the substrate. Inkdrop ejection chambers are disposed between opposed surfaces of the first and second sections of the substrate. Ink inlet orifices are provided in the first section of the substrate and each of the ink inlet orifices are in fluid communication with a respective one of the inkdrop ejection chambers. Ink outlet apertures are provided in the second section of the substrate and each of the ink outlet apertures are in fluid flow communication with a respective one of the inkdrop ejection chambers.

Abstract: Selected portions of the orifice plate surfaces are formed to have wetting and non-wetting surface characteristics for minimizing the accumulation of residual ink on the outer surface of the plate and for enhancing the flow of supply ink to the orifices of the plate.

Abstract: An ink fill slot 18 can be precisely manufactured in a substrate 12 utilizing photolithographic techniques with chemical etching. N-type <100> silicon wafers are double-side coated with a dielectric layer 26 comprising a silicon dioxide layer and/or a silicon nitride layer. A photoresist step, mask alignment, and plasma etch treatment precede an anisotropic etch process, which employs an anisotropic etchant for silicon such as KOH or ethylene diamine para-catechol. The anisotropic etch is done from the backside 12b of the wafer to the frontside 12a, and terminates on the dielectric layer on the frontside. The dielectric layer on the frontside creates a flat surface for further photoresist processing of thin film resistors 16.

Abstract: A method of manufacturing a thermal ink jet printhead wherein a reusable mandrel consisting of either a metal pattern on an insulating or semiconductive substrate or an insulating pattern on a metal substrate or metal layer is used in the process of electroforming a plurality of metal substrates used for starting a batch fabrication process. Next, thin film layers of insulating, resistive, and conductive materials are formed on the surfaces of the metal substrates to thereby define heater resistors and lead-in conductors for the plurality of thermal ink jet printheads being formed. Then, a barrier layer such as Vacrel is photodefined on the surface of the thin film insulating, resistive, and conductive layers to thereby define a plurality of ink drop ejection chambers surrounding each of the previously formed heater resistors. Next, a plurality of orifice plates are secured, respectively, to the barrier layers in each of the printheads being formed.

Abstract: An orifice plate is thermally bonded to a thick film photopolymer spacer fabricated on a print head substrate using heat and compression. The compression is applied by pressurized gas to a pliable sheet covering the orifice plate and substrate assembly. Heat can be supplied through a vacuum chuck on which the assembly is mounted or from a heating element embedded in the pliable sheet. An apparatus comprising an air actuated ram with a flange having an o-ring seated within is used to seal the pliable sheet against the vacuum chuck circumferentially about the assembly. The ram includes a chamber with an open end which is sealed against the pliable sheet when in an engaged position. By filling the chamber with gas under sufficient pressure while heating the spacer forms a bond between the orifice plate and the assembly. After thermal bonding, curing of the photopolymer spacer can be completed in an oven.

Abstract: A thermal ink jet head incorporates bubble-generating resistors, each with a relatively thick layer of unpassivated resistive material, such as TaAl. The thermal ink jet head includes an ink source, ink channels, respective orifices, and circuitry for providing the electrical energy which the resistors convert to heat to form bubbles which expel ink through respective orifices. A range between 3,000 .ANG. and 5,000 .ANG. is preferred for the resistive material to minimize failure rate while avoiding thermal, electrical and manufacturing limitations of passivated resistors.

Abstract: Off-setting the orifice (20) from the resistor (10) in a thermal ink-jet printhead provides improved print quality by controlling misdirection of first drops (26), second and subsequent drops (28) in multidrop printing, and for satellite drop control.

Abstract: A three-sided barrier structure (22), comprising three walls (24a-c), is provided in conjunction with a resistor (10) used in a thermal ink-jet printhead. Placement of the structure less than about 25 .mu.m from the resistor results in longer resistor life and an improvement in the static bubble purging ability of the printhead.

Abstract: A thermal ink jet printer is disclosed in which ink droplets are ejected from an orifice by the explosive formation of a vapor bubble within the ink supply due to the application of a two part electrical pulse to a resistor within the ink supply. The electrical pulse comprises a precurser pulse and a nucleation pulse; the precurser pulse preheats the ink in the vicinity of the resistor to a temperature below the boiling temperature of the ink so as to preheat the ink while avoiding vapor bubble nucleation within the ink supply and the subsequently occuring nucleation pulse very quickly heats the resistor to near the superheat limit of the ink.

Abstract: An improved impulse jet head structure utilizing etched silicon as the body of the structure. A silicon substrate is etched so as to form a nozzle groove, cavity, and ink supply groove. A layer of glass or other material is bonded to the top of the substrate so as to enclose the cavity and define, along with the grooves, and ink supply conduit and a nozzle conduit. A second layer of glass or other material is bonded to the bottom of the substrate and comprises the bottom surface of the cavity. A piezoelectric crystal driver is bonded to the bottom layer in a position corresponding to the location of the reservoir. An ink supply tube is bonded to the upper layer in a location above the supply groove and delivers ink to the head structure. The etching process may be utilized to form either single or multiple orifice head structures.

Abstract: An improved ink jet print head structure. The print head includes a cylindrical glass rod having a bore extending along the axis of the rod. A surface is ground on the rod parallel to and near the bore. A metal organic paste is fired on the surface and a piezoelectric driver plate is soldered to the paste. A silicon nozzle plate is bonded to the front of the rod by means of an anodic bonding technique. The head structure may be attached to a charging electrode by means of an insulating support member, resulting in a prealigned and easily replaceable unit. Several alternative embodiments of the head structure and means for attaching the structure to an input line are disclosed.

Abstract: In an ink jet printing system, a single nozzle or an array of nozzles are etched in a semiconductor material such as silicon. Each nozzle has polygonal or N-sided entrance and exit apertures of different cross-sectional area. Preferably, the nozzle is in the shape of a truncated pyramid with the entrance and exit apertures being substantially square in cross-section. The corners of the apertures and wall interfaces may be rounded to reduce stress concentrations.

Abstract: The practice of this disclosure obtains a monolithic structure useful for electrohydrodynamically synchronizing the formation of droplets in a jet stream exiting from a jet nozzle. The monolithic structure is primarily adaptable for ink jet printing. The jet nozzle structure provided by the practice of this disclosure includes a jet nozzle design in a crystalline semiconductor block, e.g., of silicon (Si), germanium (Ge) or gallium arsenide (GaAs), with an electrode structure which is integrally incorporated therewith whereby a variable electric field is established proximate to the orifice of the jet nozzle structure. The electric field electrohydrodynamically perturbs the jet stream emitting from the jet nozzle structure so that formation of drops in the jet stream is controllably achieved, e.g., synchronously when the variable electric field is oscillating with a given periodicity.