Nozzle assembly incorporating a shuttered actuation mechanism
A nozzle assembly is provided for an inkjet printer. The assembly includes a wafer arrangement defining an ink supply channel. A border is constructed on the wafer arrangement and bounds the ink supply channel. A cover layer is constructed on the border to define a nozzle chamber. The cover layer also defines an ink ejection port in fluid communication with the nozzle chamber. A shutter arrangement is constructed on the wafer arrangement and within the border. The shutter arrangement includes a thermal actuator which terminates in a shutter. The thermal actuator includes a coiled heater which, in use, can move the shutter with respect to the ink ejection port.
1. A nozzle assembly for an inkjet printer, the assembly comprising:
a wafer arrangement defining an ink supply channel;
a border constructed on the wafer arrangement and bounding the ink supply channel;
a cover layer constructed on the border to define a nozzle chamber, the cover layer defining an ink ejection port; and
a shutter arrangement constructed on the wafer arrangement and within the border, the shutter arrangement comprising a thermal actuator which terminates in a shutter, the thermal actuator comprising a coiled heater which, in use, can move the shutter with respect to the ink ejection port.
2. A nozzle assembly as claimed in claim 1 , wherein the coiled heater comprises a serpentine heating element sandwiched between a pair of polytetrafluoroethylene (PTFE) layers.
3. A nozzle assembly as claimed in claim 1 , further comprising:
an ink reservoir which is in fluid communication with the ink supply channel; and
an ultrasonic transducer positioned in the reservoir.
4. A nozzle assembly as claimed in claim 1 , wherein the ultrasonic transducer is a piezoelectric transducer which oscillates at approximately 100 kHz.
5. A nozzle assembly as claimed in claim 1 , wherein the wafer arrangement comprises a silicon wafer, a Complementary Metal Oxide Semiconductor (CMOS) layer constructed on the silicon wafer and comprising CMOS circuitry, and a nitride layer constructed on top of the CMOS layer.
6. A nozzle assembly as claimed in claim 1 , wherein the border and cover layers are formed from nitride material.
7. A nozzle assembly as claimed in claim 1 , wherein the ink supply channel is wider than the ejection port.
8. A nozzle assembly as claimed in claim 1 , wherein the shutter arrangement is arranged so that the shutter is normally in alignment with the ink ejection port and, upon actuation of the thermal actuator, is moved out of alignment with the ink ejection port by uncoiling the coiled heater.