Printhead having multiple thermal actuators for ink ejection
View Patent ↗An inkjet printhead is provided including a substrate defining chambers for storing ink, with each chamber having an ink ejection port and actuators arranged to bend upon actuation to displace the port thereby ejecting ink therefrom. Each actuator incorporates a conductive resistive heating element encased within a material having a high coefficient of thermal expansion. Each heating element is configured to cause uneven expansion of the encasing material upon heating so that the actuator bends in a predetermined direction.
1. An inkjet printhead comprising a substrate defining a plurality of chambers for storing ink, each chamber having a wall with an ink ejection port and a plurality of actuators arranged in the wall on the same plane as the port so as to bend upon actuation to displace the port thereby ejecting ink therefrom, each actuator incorporating a conductive resistive heating element having a serpentine form and encased within a material having a high coefficient of thermal expansion, each heating element being configured to cause uneven expansion of the encasing material upon heating so that the associated actuator bends in a predetermined direction.
2. An inkjet printhead according to claim 1 , wherein each heating element is configured to cause the associated actuator to bend inwards away from the centre of the chamber upon heating.
3. An inkjet printhead according to claim 1 , wherein the actuators of each chamber are arranged radially around the associated port.
4. An inkjet printhead according to claim 1 , wherein the actuators of each chamber form a membrane between the interior and exterior of the chamber.
5. An inkjet printhead according to claim 4 , wherein the heating elements of each chamber are configured to cause the associated actuators to bend away from the exterior of the chamber to cause an increase in ink pressure within the chamber thereby initiating a consequential ejection of ink from the associated port.
6. An inkjet printhead according to claim 1 , wherein each heating element is configured to cause the associated actuator to bend away from a central axis of the associated port.
7. An inkjet printhead according to claim 1 , wherein the substrate further defines a plurality of ink supply channels, each channel being in fluid communication with a respective chamber.
8. An inkjet printhead according to claim 1 , wherein each chambers has a series of struts which support the associated port in spaced relationship from the substrate.
9. An inkjet printhead according to claim 1 , wherein the chambers are defined within the substrate in an array so as to form a pagewidth printhead.