Thermal ink jet printhead with heaters formed from low atomic number elements
View Patent ↗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 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 ( 16 ) of an ejectable liquid (such as ink) through the respective corresponding nozzle, to effect printing. Each heater element is formed of solid material, more than 90% of which, by atomic proportion, is constituted by at least one element, from the periodic table of elements, having an atomic number below 50.
1. An ink jet printhead comprising:
a plurality of nozzles; and
at least one respective heater element corresponding to each nozzle, wherein
each heater element is formed of solid material more than 90% of which, by atomic proportion, is constituted by at least one periodic element having an atomic number below 50,
each heater element is arranged for being in thermal contact with a bubble forming liquid;
each heater element is configured to receive a pulse of actuation energy that the heater element uses to heat at least part of the bubble forming liquid to a temperature above its boiling point to form a gas bubble therein thereby to cause the ejection of a drop of the bubble forming liquid through the nozzle corresponding to that heater element, the pulse of actuation energy having a duration less than 0.5 microseconds; and
wherein the bubble which each heater element is configured to form is collapsible and has a point of collapse, and wherein each heater element is configured such that the point of collapse of a bubble formed thereby is spaced from that heater element.
2. The printhead of claim 1 being configured to support the bubble forming liquid in thermal contact with each said heater element.
3. The printhead of claim 1 being configured to print on a page and to be a page-width printhead.
4. The printhead of claim 1 wherein said atomic number is below 30.
5. The printhead of claim 1 wherein said atomic number is below 23.
6. The printhead of claim 1 wherein each heater element is in the form of a suspended beam, that is suspended over at least a portion of the bubble forming liquid so as to be in thermal contact therewith.
7. The printhead of claim 1 wherein each heater element is configured such that an actuation energy of less than 500 nanojoules (nJ) is required to be applied to that heater element to heat that heater element sufficiently to form said bubble in the bubble forming liquid thereby to cause the ejection of said drop.
8. The printhead of claim 1 configured to receive a supply of the bubble forming liquid at an ambient temperature, wherein each heater element is configured such that the energy required to be applied thereto to heat said part to cause the ejection of said drop 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 said boiling point.
9. The printhead of claim 1 comprising a substrate having a substrate surface, wherein each nozzle has a nozzle aperture opening through the substrate surface, and wherein the areal density of the nozzles relative to the substrate surface exceeds 10,000 nozzles per square cm of substrate surface.
10. The printhead of claim 1 wherein each heater element has a pair of planar surfaces on opposite sides of the element, that element being suspended such that each of the planar surfaces is in thermal contact with the bubble forming liquid such that the bubble is formed at both of the element surfaces.
11. The printhead of claim 1 comprising a structure that is formed by chemical vapor deposition (CVD), said nozzles being incorporated on the structure.
12. The printhead of claim 1 comprising a structure which is less than 10 microns thick, said nozzles being incorporated in the structure.
13. The printhead of claim 1 comprising a plurality of nozzle chambers each corresponding to a respective nozzle, and a plurality of said heater elements being disposed within each chamber, the heater elements within each chamber being formed in different respective layers.
14. The printhead of claim 1 wherein each heater element includes solid material and has a mass of less than 10 nanograms of the solid material of that heater element to be heated to a temperature above said boiling point thereby to heat said part of the bubble forming liquid to a temperature above said boiling point to cause the ejection of said drop.
15. The printhead of claim 1 wherein each heater element is substantially covered by a conformal protective coating, the coating of each heater element having been applied substantially to all sides of the heater element simultaneously such that the coating is seamless.
16. A printer system incorporating a printhead, the printhead comprising:
a plurality of nozzles; and
at least one respective heater element corresponding to each nozzle, wherein
each heater element is formed of solid material more than 90% of which, by atomic proportion, is constituted by at least one periodic element having an atomic number below 50,
each heater element is arranged for being in thermal contact with a bubble forming liquid;
each heater element is configured to receive a pulse of actuation energy that the heater element uses to heat at least part of the bubble forming liquid to a temperature above its boiling point to form a gas bubble therein thereby to cause the ejection of a drop of the bubble forming liquid through the nozzle corresponding to that heater element, the pulse of actuation energy having a duration less than 0.5 microseconds; and
wherein the bubble which each heater element is configured to form is collapsible and has a point of collapse, and wherein each heater element is configured such that the point of collapse of a bubble formed thereby is spaced from that heater element.
17. The system of claim 16 being configured to support the bubble forming liquid in thermal contact with each said heater element.
18. The system of claim 16 being configured to print on a page and to be a page-width printhead.
19. The system of claim 16 wherein said atomic number is below 30.
20. The system of claim 16 wherein said atomic number is below 23.
21. The system of claim 16 wherein each heater element is in the form of a suspended beam, that is suspended over at least a portion of the bubble forming liquid so as to be in thermal contact therewith.
22. The system of claim 16 wherein each heater element is configured such that an actuation energy of less than 500 nanojoules (nJ) is required to be applied to that heater element to heat that heater element sufficiently to form said bubble in the bubble forming liquid thereby to cause the ejection of said drop.
23. The system of claim 16 , wherein the printhead is configured to receive a supply of the bubble forming liquid at an ambient temperature, and wherein each heater element is configured such that the energy required to be applied thereto to heat said part to cause the ejection of said drop 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 said boiling point.
24. The system of claim 16 comprising a substrate having a substrate surface, wherein each nozzle has a nozzle aperture opening through the substrate surface, and wherein the areal density of the nozzles relative to the substrate surface exceeds 10,000 nozzles per square cm of substrate surface.
25. The system of claim 16 wherein each heater element has a pair of planar surfaces on opposite sides of the element, the element being suspended such that each of the planar surfaces is in thermal contact with the bubble forming liquid such that the bubble is formed at both of the element surfaces.
26. The system of claim 16 comprising a structure that is formed by chemical vapor deposition (CVD), said nozzles being incorporated in the structure.
27. The system of claim 16 comprising a structure which is less than 10 microns thick, said nozzles being incorporated in the structure.
28. The system of claim 16 comprising a plurality of nozzle chambers each corresponding to a respective nozzle, and a plurality of said heater elements being disposed within each chamber, the heater elements within each chamber being formed in different respective layers.
29. The system of claim 16 wherein each heater element includes solid material and has a mass of less than 10 nanograms of the solid material of that heater element to be heated to a temperature above said boiling point thereby to heat said part of the bubble forming liquid to a temperature above said boiling point to cause the ejection of said drop.
30. The system of claim 16 wherein each heater element is substantially covered by a conformal protective coating, the coating of each heater element having been applied substantially to all sides of the heater element simultaneously such that the coating is seamless.
31. A method of ejecting a drop of a bubble forming liquid from a printhead, the printhead comprising a plurality of nozzles, the method comprising the steps of:
providing the printhead wherein the printhead comprises at least one respective heater element corresponding to each nozzle, each heater element being formed of solid material more than 90% of which, by atomic proportion, is constituted by at least one periodic element having an atomic number below 50;
providing a heater clement with a pulse of actuation so as to heat at least part of a bubble forming liquid which is in thermal contact with the at least one heated heater element to a temperature above the boiling point of the bubble forming liquid, the pulse of actuation energy having a duration less than 0.5 microseconds;
generating a gas bubble in the bubble forming liquid by said step of heating;
causing the drop of bubble forming liquid to be ejected through the nozzle corresponding to the at least one heated heater element by said step of generating a gas bubble, and
collapsing the bubble to a point of collapse spaced from the heated heater element.
32. The method of claim 31 comprising, before said step of heating, the steps of:
disposing the bubble forming liquid in thermal contact with the heater elements.
33. The method of claim 31 wherein, in said step of providing the printhead, said atomic number is below 30.
34. The method of claim 31 wherein, in said step of providing the printhead, said atomic number is below 23.
35. The method of claim 31 wherein each heater element is in the form of a suspended beam, the method further comprising, prior to the step of heating at least one heater element, of disposing the bubble forming liquid such that the heater elements are positioned above, and in thermal contact with, at least a portion of the bubble forming liquid.
36. The method of claim 31 wherein the step of heating at least one heater element is effected by applying an actuation energy of less than 500 nJ to each such heater element.
37. The method of claim 31 , comprising, prior to the step of heating at least one heater element, the step of receiving a supply of the bubble forming liquid, at an ambient temperature, to the printhead, wherein the step of heating is effected by applying heat energy to each such heater element, wherein said applied heat energy is less than the energy required to heat a volume of said bubble forming liquid equal to the volume of said drop, from a temperature equal to said ambient temperature to said boiling point.
38. The method of claim 31 wherein, in the step of providing the printhead, the printhead includes a substrate in which said nozzles are disposed, the substrate having a substrate surface, and the areal density of the nozzles relative to the substrate surface exceeding 10,000 nozzles per square cm of substrate surface.
39. The method of claim 31 wherein each heater element has a pair of planar surfaces on opposite sides of the element and wherein, in the step of generating a gas bubble, the bubble is generated at both of said planar surfaces of each heated heater element.
40. The method of claim 31 wherein the step of providing the printhead includes forming a structure by chemical vapor deposition (CVD), the structure incorporating the nozzles therein.
41. The method of claim 31 wherein, in the step of providing the printhead, the printhead has a structure which is less that 10 microns thick and which incorporates said nozzles therein.
42. The method of claim 31 wherein the printhead has a plurality of nozzle chambers each chamber corresponding to a respective nozzle and wherein the step of providing the printhead includes forming a plurality of said heater elements in each chamber, such that the heater elements in each chamber are formed in different respective layers to one another.
43. The method of claim 31 wherein each heater element includes solid material and has a mass less than 10 nanograms, and wherein the step of heating at least one heater element includes heating the solid material of each such heater element to a temperature above said boiling point.
44. The method of claim 31 wherein the step of providing the printhead includes applying to each heater element, substantially to all sides thereof simultaneously, a conformal protective coating such that the coating is seamless.
45. The printhead of claim 1 wherein each nozzle has a nozzle aperture and defines an axis extending through the nozzle aperture, wherein the point of collapse is disposed on the axis and wherein the element is configured so that the element is spaced from the axis.
46. The system of claim 16 wherein each nozzle has a nozzle aperture and defines an axis extending through the nozzle aperture, the nozzle being disposed about the axis, wherein the point of collapse is disposed on the axis and wherein the element is configured so that the element is spaced from the axis.
47. The method of claim 31 wherein each nozzle has a nozzle aperture and defines an axis extending through the nozzle aperture, the nozzle being disposed about the axis, and the element being spaced from the axis, and wherein, the gas bubble is collapsed to a point of collapse disposed on the axis.