Magnetic drive systems and methods for a micromachined fluid ejector

Abstract

The systems and methods of the present invention operate by magnetically driving a fluid ejector. In various exemplary embodiments, a primary coil and a secondary coil are situated in the ejector. The ejector has a movable piston usable to eject fluid through a nozzle hole. The piston may be resiliently mounted and biased to an at-rest position. A drive signal is applied to cause current to flow in the primary coil. The current flow generates a magnetic field that induces a current in the secondary coil. Either the primary coil or the secondary coil or associated with the piston and the other is associated with a fixed structure of the ejector. As a result, a magnetic force is generated that pushes the piston either toward a faceplate so that a drop of fluid is ejected through the nozzle hole in the faceplate or away from the faceplate so that fluid fills in a fluid chamber between the piston and the faceplate. When the drive signal is turned off, the piston resiliently returns to its at-rest position, thereby either refilling the ejected fluid or ejecting a drop of fluid through the nozzle hole in the faceplate. In various other embodiments, the faceplate is made of a magnetic material, such as a ferrous material, or is coated with or connected to a magnetic material. A second primary coil or a permanent magnet may be included in various other embodiments. In various embodiments, switching the direction of the current changes the magnetic force between attraction and repulsion.