Abstract: A thermal inkjet printhead with heater elements disposed in respective bubble forming chambers for heating a water-based printing fluid to form a gas bubble for ejecting a drop of the printing fluid from the nozzle. The heater is separated from the nozzle by less than 5 ?m at their closest points and the nozzle length is less than 5 ?m. The volume of liquid between the heater and the nozzle determines the inertia of the liquid and its acceleration in response to bubble formation. Moving the heater closer to the nozzle reduces the inertia of the liquid and increases its acceleration, so a lower bubble impulse is needed to eject a drop. This allows the printhead to use smaller heater elements with lower power requirements. Viscous drag in the nozzle reduces the momentum of fluid flowing through the nozzle. The viscous drag increases as the nozzle length (in the direction of fluid flow) increases. By reducing the nozzle length, a lower bubble impulse is needed to eject a drop.

Abstract: An inkjet printhead that has a plurality of nozzles and respective heater elements, together with drive circuitry that can send a pulse of electrical energy to each heater element to form a vapor bubble in the printing fluid that ejects a drop of printing fluid through the nozzle. The pulse of electrical energy is less than 200 nanoJoules so that the power consumption of the printhead is low. This configuration provides for very efficient operation.

Abstract: A MEMS vapor bubble generator with a chamber for holding liquid and a heater positioned in the chamber for heating the liquid above its bubble nucleation point to form a vapour bubble; wherein, the heater is formed from a superalloy.

Abstract: A MEMS vapor bubble generator with a chamber for holding liquid and a heater positioned in the chamber for heating the liquid above its bubble nucleation point to form a vapour bubble; wherein, the heater has a microstructure with a grain size less than 100 nanometres.

Abstract: A fluid sensor for detecting fluid in a chamber, has a MEMS sensing element of conductive material with a resistance that is a function of temperature, and electrical contacts for connection to an electrical power source for heating the sensing element with an electrical signal, so that control circuitry can measure the current passing through the sensing element during heating of the sensing element; and determine the temperature of the sensing element from the known applied voltage, the measured current and the known relationship between the current, resistance and temperature. As the temperature of the element will be greater if it is in the presence of gas rather than liquid, the sensor determines if there is liquid or gas in the chamber. This is particularly useful to detect if the chambers of an inkjet printhead are primed with ink.

Abstract: A thermal inkjet printhead with heater elements formed from a self passivating transition metal nitride, but it oxidizes readily. By introducing an additive that allows the metal nitride to self passivate, the heater element forms a surface oxide layer, where the oxide has a low diffusion coefficient for oxygen so as to provide a barrier to further oxidation. With enhanced oxidation resistance, coatings to protect the heater from oxidative failure become unnecessary and the energy needed to form a bubble is reduced.

Abstract: A thermal inkjet printhead with a heater element disposed in each of the bubble forming chambers wherein, the heater element has a protective surface coating that is less than 0.1 ?m thick while still being capable of ejecting more than 1 billion drops without failure. Removing most or all of the protective coatings from the heater reduces or eliminates the thermal insulation between the heater and the ink. Nucleating a bubble in the ink chamber requires a much shorter pulse of less energy thereby improving printhead efficiency.

Abstract: A thermal inkjet printhead with bubble forming heater elements formed from a material with a nanocrystalline composite structure. Nanocrystalline composite films can be superhard and can facilitate removal of the SiC and Ta anti-cavitation wear coatings. Improved oxidation resistance can also be achieved with some nanocrystalline composites, facilitating removal of the Si3N4 oxidation prevention coating. By removing or reducing the protective coatings, the heater element requires much less energy to form a bubble in the ink. A further benefit is improved crack resistance, which can extend the lifetime of uncoated heaters.

Abstract: A thermal inkjet printhead with generally planar heater elements disposed in respective bubble forming chambers such that they are bonded on one side to the chamber so that the other side faces into the chamber. Each heater element receives an energizing pulse to heat ejectable liquid above its boiling point to form a gas bubble on the side facing into the chamber, whereby the gas bubble causes the ejection of a drop of the ejectable liquid from the nozzle. The chamber has a dielectric layer proximate the side of the heater element bonded to the chamber. The dielectric layer has a thermal product less than 1495 Jm?2K?1s?1/2, the thermal product being (?Ck)1/2, where ? is the density of the layer, C is specific heat of the layer and k is thermal conductivity of the layer. The present invention reduces the drop ejection energy and the heat dissipation into the printhead IC by improving the thermal isolation between the heater and the substrate.

Abstract: An inkjet printhead with a plurality of nozzles, a bubble forming chamber corresponding to each of the nozzles respectively, the bubble forming chambers adapted to contain ejectable liquid, a heater element positioned in each of the bubble forming chambers respectively for heating the ejectable liquid to form a gas bubble that causes the ejection of a drop of the ejectable liquid from the nozzle; and, a print engine controller for controlling the operation of the heater elements; wherein during use, the print engine controller heats the ejectable liquid with the heater element to lower its viscosity prior to a print job; and during printing, the print engine controller ensures that the time interval between successive actuations of each of the heater elements is less than a predetermined time in which the viscosity of the ejectable liquid in the increases to a threshold.

Abstract: There is disclosed an ink jet printhead which comprises a plurality of nozzles (3) and one or more heater elements (10) corresponding to each nozzle. Each heater element is configured to heat a bubble (12) forming liquid in the printhead to a temperature above its boiling point to form a gas bubble therein. The generation of the bubble causes the ejection of a drop (16) of an ejectable liquid (such as ink) through respective corresponding nozzle, to effect printing. Each heater element is in the form of a beam suspended over at least a portion of the bubble forming liquid so as to be in thermal contact therewith. This configuration of printhead provides for a relatively high efficiency of operation.

Abstract: There is disclosed an inkjet printhead which comprises a plurality of nozzles (3) and one or more heater elements (10) corresponding to each nozzle (3). Each heater element is configured to heat a bubble forming liquid in the printhead to a temperature above its boiling point to form a gas bubble (12) therein. The generation of the bubble causes the ejection of a drop of an ejectable liquid (such as ink) through the respective corresponding nozzle, to effect printing. Each heater element is configured such that an actuation energy of less than 500 nanojoules (nJ) is required to be applied to that element to heat it sufficiently to form such a bubble (12) in the bubble forming liquid (which liquid can also be the ink). This configuration thus provides for a high efficiency printhead.

Abstract: An inkjet printhead (1) which a plurality of nozzles (3) and one or more heater elements (10) corresponding to each nozzle. Each heater is configured to heat a bubble forming liquid in the printhead to a temperature above its boiling. Each heater element has two opposite sides and is suspended within the chamber (7) below the nozzle. The gas bubble is formed at both sides of the heater.

Abstract: There is disclosed an ink jet printhead which comprises a plurality of nozzles (3) and one or more heater elements (10) corresponding to each nozzle (3). Each heater element is configured to heat a bubble forming liquid in the printhead to a temperature above its boiling point to form a gas bubble (12) therein. The generation of the bubble causes the ejection of a drop of an ejectable liquid (such as ink) though the respective corresponding nozzle, to effect printing. Each heater element is substantially covered by a conformal protective coating (77) which has been applied to all sides of the heater element (10) simultaneously so that the coating is seamless.

Abstract: There is disclosed an inkjet printhead integrated which comprises drive circuitry, a plurality of nozzles and one or more heater elements corresponding to each nozzle. Each heater element is configured to heat a bubble forming liquid in the printhead to a temperature above its boiling point to form a gas bubble therein. The generation of the bubble causes the ejection of a drop of an ejectable liquid (such as ink) through respective corresponding nozzle, to effect printing. Each heater element has a surface area to volume ratio greater than 4:1. This configuration ensures that heat is quickly transferred from the elements to the ink for efficient operation and minimal heating of the printhead substrate.

Abstract: A thermal inkjet printhead with heater elements disposed in respective bubble forming chambers whereby each heater element is configured for receiving an energizing pulse to form a gas bubble in an ejectable liquid that causes the ejection of a drop of the ejectable liquid from the nozzle. The energizing pulse has duration less than 1.5 micro-seconds (?s) and the nozzles are “self cooling”, in the sense that in the sense that the only heat removal required by the chip is the heat removed by ejected droplets. The printhead is designed for operation with reduced pulse duration, so the amount of heat that diffuses into the liquid and the substrate prior to nucleation of the vapor bubble is reduced. This facilitates self cooling operation.

Abstract: A thermal inkjet printhead with heater elements disposed in respective bubble forming chambers for heating part of the ejectable liquid above its boiling point to form a gas bubble that causes the ejection of a drop of the ejectable liquid from the nozzle, wherein, the heater is separated from the nozzle by less than 5 ?m at their closest points; the nozzle length is less than 5 ?m; and the ejectable liquid has a viscosity less than 5 cP. The volume of liquid between the heater and the nozzle determines the inertia of the liquid and its acceleration in response to bubble formation. Moving the heater closer to the nozzle reduces the inertia of the liquid and increases its acceleration, so a lower bubble impulse is needed to eject a drop. This allows the printhead to use smaller heater elements with lower power requirements. Viscous drag in the nozzle reduces the momentum of fluid flowing through the nozzle. The viscous drag increases as the nozzle length (in the direction of fluid flow) increases.

Abstract: A thermal inkjet printhead with generally planar heater elements disposed in respective bubble forming chambers, whereby the area of each heater is less than 300 ?m2. The heater area influences: 1. the energy required to heat the heater volume up to the fluid superheat limit; 2. the energy required to heat the protective coatings covering the heater to the superheat limit; 3. the heat that diffuses into the underlayer prior to bubble nucleation; and, 4. the heat that diffuses into the ink prior to bubble nucleation. Reducing the surface area of the heater reduces all of these terms and has a significant impact on the energy required to form a bubble and eject ink.