Fluid ejection device with inner and outer arms
View Patent ↗A microelectromechanical fluid ejection device, comprising a mechanical actuator ( 28 ), an outer arm portion ( 31 ) and an inner arm portion ( 32 ), the actuator ( 28 ) being displaceable upon receipt of an electrical current in the inner arm portion ( 32 ), the outer arm portion ( 31 ) electrically isolated from the inner arm portion ( 32 ), said displacement causing ejection of fluid from an aperture ( 26 ) in the device, and, drive circuitry for supplying the electrical current to the inner arm portion ( 32 ).
1. A microelectromechanical fluid ejection device, said device comprising:
a mechanical actuator comprising an outer arm portion and an inner arm portion, said actuator being displaceable upon receipt of an electrical current in said inner arm portion, said outer arm portion electrically isolated from said inner arm portion, said displacement causing ejection of fluid from an aperture in the device; and,
drive circuitry for supplying the electrical current to said inner arm portion;
wherein the current causes heating of said inner arm portion, and the heating causes elongation of said inner arm portion, inducing bending of said actuator.
2. The device as claimed in claim 1 , wherein said drive circuitry causes a pulsed current to flow in said inner arm portion.
3. The device as claimed in claim 1 , wherein said outer arm portion is electrically isolated from said inner arm portion by posts.
4. The device as claimed in claim 1 , wherein the device further comprises:
a switch device for determining an extent of displacement of the actuator, said switch device comprising:
a contact element positioned for contact with the actuator at a predetermined extent of displacement; and,
processing circuitry for detecting when the actuator makes contact with said contact element.
5. The device as claimed in claim 4 , wherein the current is directed to the processing circuitry when the actuator makes contact with the contact element.
6. The device as claimed in claim 4 , wherein the processing circuitry is configured for registering a fault condition when the actuator makes contact with the contact element.
7. The device as claimed in claim 1 , further comprising a paddle connected to the actuator, the paddle being displaced upon actuation of the actuator, thereby ejecting fluid from the aperture.
8. The device as claimed in claim 1 , wherein the paddle is suspended in an ink chamber.