Thermal ink jet printhead with unintentional boiling prevention
AssigneeSilverbrook Research Pty Ltd
InventorKia Silverbrook
Life of this patent
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Abstract
There is disclosed an ink jet printhead which has a plurality of nozzles 3 and one or more heater elements 10 corresponding to each nozzle 3. Each heater element 10. is configured to heat a bubble forming liquid 11 in the printhead to a temperature above its boiling point to form a gas bubble 12 therein. The generation of the bubble 12 causes the ejection of a drop 16 of an ejectable liquid (such as ink) through an ejection aperture 5 in each nozzle 3, to effect printing. The heat energy difference between an ejected drop of the ejectable liquid and an equivalent volume of the ejectable liquid supplied to the nozzle to replace the ejected drop, is substantially equal to the electrical energy required by the heater to eject the drop.
Claims51
An ink jet printhead comprising:
- a plurality of nozzles adapted for supply with an ejectable liquid;
- and,
- a heater corresponding to each of the nozzles respectively, the heater having at least one heater element configured for thermal contact with a bubble forming liquid;
- such that,
- heating the heater element to a temperature above the boiling point of the bubble forming liquid forms a gas bubble that causes the ejection of a drop of the ejectable liquid from the nozzle;
- wherein,
- the heater element is configured so that the heat energy of an ejected drop differs from the heat energy of an equivalent volume of the ejectable liquid supplied to the nozzle to replace the drop, the heat energy difference being substantially equal to the electrical energy the heater requires to eject the drop, and the nozzle and an inlet though which the ejectable liciuid is supplied to the nozzle are configured so that the outgoing heat energy due to the net effect of the ejected and replacement quantities of ejectable liquid is substantially equal to the amount of heat energy added to the ejectable liquid by the heater element;
- such that,
- after the gas bubble collapses and before the heater subsequently activates, the temperature of the bubble forming liquid is at least 10 degrees C. cooler than its boiling point.
A printer system which incorporates a printhead, the printhead comprising:
- an ink jet printhead comprising:
- a plurality of nozzles adapted for supply with an ejectable liquid;
- and,
- a heater corresponding to each of the nozzles respectively, the heater having at least one heater element configured for thermal contact with a bubble forming liquid;
- such that,
- heating the heater element to a temperature above the boiling point of the bubble forming liquid forms a gas bubble that causes the ejection of a drop of the ejectable liquid from the nozzle;
- wherein,
- the heater element is configured so that the heat energy of an ejected drop differs from the heat energy of an equivalent volume of the ejectable liquid supplied to the nozzle to replace the drop, the heat energy difference being substantially equal to the electrical energy the heater requires to eject the drop, and the nozzle and an inlet though which the ejectable liquid is supplied to the nozzle are configured so that the outgoing heat energy due to the net effect of the ejected and replacement quantities of ejectable liquid is substantially equal to the amount of heat energy added to the ejectable liciuid by the heater element;
- such that,
- after the gas bubble collapses and before the heater subsequently activates, the temperature of the bubble forming liquid is at least 10 degrees C. cooler than its boiling point.
A method of ejecting drops of an ejectable liquid from a printhead, the printhead comprising a plurality of nozzles adapted for supply with an ejectable liquid;
- and, a heater corresponding to each of the nozzles respectively, the heater having at least one heater element configured for thermal contact with a bubble forming liquid;
- wherein,
- the heater element is configured so that the heat energy of an ejected drop differs from the heat energy of an equivalent volume of the ejectable liquid supplied to the nozzle to replace the drop, the heat energy difference being substantially equal to the electrical energy the heater requires to eject the drop, and the nozzle and an inlet though which the ejectable liquid is supplied to the nozzle are configured so that the outgoing heat energy due to the net effect of the ejected and replacement quantities of ejectable liquid is substantially equal to the amount of heat energy added to the ejectable liquid by the heater element;
- such that,
- after the gas bubble collapses and before the heater subsequently activates, the temperature of the bubble forming liquid is at least 10 degrees C. cooler than its boiling point;
- the method comprising the steps of:
- heating the heater elements to a temperature above the boiling point of the bubble forming liquid to form a gas bubble that causes the ejection of a drop of the ejectable liquid from the nozzle;
- and
- supplying the nozzle with a replacement volume of the ejectable liquid equivalent to the ejected drop.
Dependencies are inferred from the claim text.