Patent ID: 6605176
Filing Date: 2003-08-12
Classification: H01J,H01L

Abstract:
A mechanism for linearly controlling pressure of a vacuum chamber comprising: an aperture diaphragm defining a contractible and expandable aperture for controlling the pressure of the vacuum chamber;a plurality of aperture blades rotatably mounted on the aperture diaphragm, such that rotation of the plurality of aperture blades in a first direction contracts the aperture, increasing the pressure of the vacuum chamber, and such that the rotation of the plurality of aperture blades in a second direction opposite to the first direction expands the aperture, decreasing the pressure of the vacuum chamber; and a rotatable circular frame around the aperture diaphragm having a plurality of inward-facing gear teeth, wherein each aperture blade is rotatably mounted to the aperture diaphragm by a circular gear having a number of gear teeth there around that interlock with the inward-facing gear teeth of the frame, such that rotation of the frame in the first direction causes the rotation of the plurality of aperture blades in the first direction, and such that the rotation of the frame in the second direction causes the rotation of the plurality of aperture blades in the second direction, said rotatable circular frame comprises a plurality of magnets situated there around in a substantially equally spaced configuration, such that application of a magnetic field around the frame causes rotation of the frame.