Ink jet printhead with inner and outer heating loops
View Patent ↗An ink jet printhead comprising: a substrate; a plurality of chambers supported by the substrate for receiving therewithin bubble forming liquid; a nozzle aperture formed in a surface of each chamber; a beam suspended within each chamber, the beam comprising at least one respective heater element. The at least one respective heater element heats at least part of the bubble forming liquid to a temperature above its boiling point to form a gas bubble therein, thereby causing ejection of a drop of the bubble forming liquid through the nozzle aperture corresponding to the heater element.
1. An ink jet printhead comprising:
a plurality of chambers; and
a heater beam suspended within each chamber, the heater beam comprising at least an outer heating loop and an inner heating loop.
2. The ink jet printhead according to claim 1 , wherein the plurality of chambers are formed on a planar support surface and each chamber comprises:
a planar nozzle plate having a nozzle aperture, the nozzle plate being configured to be parallel to, and spaced apart from, the planar support surface,
wherein the heater beam is parallel to both the planar support surface and the planar nozzle plate.
3. The ink jet printhead according to claim 2 , wherein the at least one nozzle plate is less than 10 microns thick.
4. The ink jet printhead according to claim 1 , wherein each heating loop has two opposite planar sides and is configured such that, when the heating loops are submerged in a bubble forming liquid and heated, a gas bubble formed is formed at both of the sides of the heating loops.
5. The ink jet printhead according to claim 1 , wherein each heating loop is substantially covered by a conformal protective coating applied substantially to all sides of the heating loop simultaneously such that the coat is seamless.
6. The ink jet printhead according to claim 1 , wherein each chamber includes a nozzle aperture and an inlet in fluid communication with a supply of bubble forming liquid, heating of the heater beam causes a drop of bubble forming liquid to be ejected from the nozzle aperture, the ejection of the drop causes a change of pressure within the chamber, and the change of pressure causes a portion of the supply of bubble forming liquid to be drawn within the respective chamber.
7. The ink jet printhead according to claim 1 , wherein the heater beam is suspended so as to be immersed when the chamber is filled with bubble forming liquid.
8. The ink jet printhead according to claim 1 , wherein the heater beam is suspended above bubble forming liquid contained within the chamber.
9. The ink jet printhead according to claim 1 , wherein each chamber receives a supply of bubble forming liquid at an ambient temperature, wherein each heating loop is configured such that the energy required to be applied thereto to heat said part of the bubble forming liquid to cause ejection of a drop of bubble forming liquid is less than the energy required to heat a volume of said bubble forming liquid equal to the volume of the said drop, from a temperature equal to said ambient temperature to a boiling point.
10. The ink jet printhead according to claim 1 wherein each heater loop forms a bubble when the chamber is filled with bubble forming liquid and the heater loop is heated, wherein the bubble is collapsible and has a point of collapse is spaced from the heating loop.