Printer with microelectromechanical printhead having electro-thermal actuators incorporating heatsinks
View Patent ↗A printer includes a microelectromechanical printhead incorporating a plurality of ink ejection nozzles. Each of the ink ejection nozzles includes an ink well to contain printing fluid and an electrically operated thermal ink ejection actuator assembly. The ink ejection actuator includes a pair of substantially parallel opposed activation members that extend from a substrate and define a gap therebetween. An actuator arm extends from the distal end of the paired activation members. In use an electrical driving circuit causes differential thermal expansion of the activation members that results in the free end of the actuator arm pivoting into the ink well in order to cause ink ejection. In order to maintain a relatively constant heating temperature along the length of the activation members, heat sinks are located in the gap and extend between the paired members. The heat sinks also act to provide increased strength and functional integrity.
1. A printer including a microelectromechanical printhead incorporating a plurality of ink ejection nozzles each having an electrically operated thermal ink ejection actuator, said actuator including:
opposed activation members extending from a substrate and defining a gap therebetween;
one or more struts located in the gap and extending between said activation members; and
an actuator arm extending from an end of the opposed activation members distal from the substrate; wherein
the printhead includes electrical driving circuits connected to cause differential thermal expansion of the activation members in order to pivot the actuator arm.
2. A printer according to claim 1 , wherein the one or more struts are configured to act as heat sinks for the thermal actuators.
3. A printer according to claim 2 , wherein the one or more struts are further configured to inhibit buckling of the actuator during use.
4. A printer according to claim 1 , wherein the opposed activation members comprise first and second activation members.
5. A printer according to claim 4 , wherein the first activation member is connected to the electrical driving circuits to be thermally expanded.
6. A printer according to claim 1 , wherein the first and second activation members are substantially parallel and wherein the one or more struts extend perpendicularly therebetween.
7. A printer according to claim 1 , wherein the actuator arm has a free end arranged to eject ink from an ink well of the nozzle in use.
8. A printer according to claim 7 , wherein the activation members are made from titanium nitride.