Inkjet printhead having a thermal actuator coil
View Patent ↗An inkjet printhead comprises an array of nozzles each having an ink chamber and a nozzle opening through which ink is ejected. A paddle moves within the chamber between first and second positions to cause ink ejection, the paddle being actuated by a thermal actuator having a resistive heating member of relatively high Young's modulus operatively connected to a passive member of relatively low Young's modulus such that heating of the resistive heating member by electrical current from drive circuitry causes deformation of the passive member and subsequent movement of the paddle.
1. An inkjet printhead comprising an array of nozzles, at least one nozzle actuated by a thermal actuator, the thermal actuator comprising:
a resistive heating member of relatively high Young's modulus operatively connected to a passive member of relatively low Young's modulus such that heating of said resistive heating member by electrical current from drive circuitry causes deformation of said passive member;
wherein said thermal actuator is a coil and wherein the coil includes a first coil formed by the resistive heating member and a second coil formed by the passive member.
2. An inkjet printhead according to claim 1 wherein said at least one nozzle comprises at least one wall defining an ink chamber; a nozzle opening in said chamber through which ink is ejected from said chamber; an ink ejection mechanism disposed within said chamber and actuatable between at least first and second positions by said thermal actuator.
3. An inkjet printhead according to claim 2 further comprising an actuator opening in said wall of said chamber; wherein said thermal actuator is disposed outside of said chamber and operatively connects to said ink ejection mechanism through an opening in said at least one wall.
4. An inkjet printhead according to claim 1 wherein the coil is a substantially planar coil.
5. An inkjet printhead according to claim 1 wherein the resistive heating coil comprises a first resistive heating coil disposed in substantial contact with the passive member and a second resistive heating coil disposed in substantial contact with the passive member, the first and second coils being electrically connected to each other at an end of the coil.
6. An inkjet printhead according to claim 1 wherein the first and second resistive heating coils include contact pads for connection to the drive circuitry, the contact pads being disposed at a centre of said coil and wherein said first and second coils are electrically connected to each other at an outer end of said coil.