Nozzle arrangement with an actuator having iris vanes

Abstract

A nozzle arrangement for an inkjet printhead includes a substrate; a plurality of posts extending from the substrate; a roof portion defining an ejection port, the roof portion supported by the plurality of posts; a plurality of vanes extending from the substrate and arranged to define a chamber with the substrate and the roof portion; and a plurality of thermal bend actuators respectively positioned at a base of each vane, each thermal bend actuator including a rigid arm and an expandable arm attached to an end of the rigid arm. Each expandable arm contains therewithin a heater element. The plurality of thermal bend actuator are adapted to bend the vanes inwards with respect to the chamber in response to an electrical signal applied to each heater element, the plurality of thermal bend actuators bending the vanes in an iris-type manner to reduce a volume of the chamber.

1 . A nozzle arrangement for an inkjet printhead, said nozzle arrangement comprising:
 a substrate;   a plurality of posts extending from the substrate;   a roof portion defining an ejection port, the roof portion supported by the plurality of posts;   a plurality of vanes extending from the substrate and arranged to define a chamber with the substrate and the roof portion; and   a plurality of thermal bend actuators respectively positioned at a base of each vane, each thermal bend actuator including a rigid arm and an expandable arm attached to an end of the rigid arm, wherein   each expandable arm contains therewithin a heater element, and   the plurality of thermal bend actuator are adapted to bend the vanes inwards with respect to the chamber in response to an electrical signal applied to each heater element, the plurality of thermal bend actuators bending the vanes in an iris-type manner to reduce a volume of the chamber.   
     
     
         2 . The nozzle arrangement of  claim 1 , wherein the rigid arm is fixed at one end to the substrate in the vicinity of one of the plurality of posts, and attached at an opposite end to the expandable arm. 
     
     
         3 . The nozzle arrangement of  claim 1 , wherein the substrate include a CMOS layer for supplying an electrical current to the heater element. 
     
     
         4 . The nozzle arrangement of  claim 3 , wherein the rigid arm of one thermal bend actuator is anchored to the substrate proximate a displaceable end of an adjacent thermal bend actuator. 
     
     
         5 . The nozzle arrangement of  claim 4 , wherein the CMOS layer supplies electrical current to the serpentine heater to cause thermal expansion of the expanding arm. 
     
     
         6 . The nozzle arrangement of  claim 1 , wherein the ink inlet in the substrate supplies the chamber with ink. 
     
     
         7 . The nozzle arrangement of  claim 2 , wherein the expanding arm is made from PTFE.