Receptacles – Closures – Pivotable
Reexamination Certificate
1999-06-07
2001-10-02
Newhouse, Nathan J. (Department: 3727)
Receptacles
Closures
Pivotable,
C220S264000, C220S827000, C206S710000, C049S386000, C016S277000, C016S286000, C016S289000
Reexamination Certificate
active
06296142
ABSTRACT:
BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
The invention relates to a lid closure and lift mechanism and, more particularly, to a counter balance spring assembly.
2. Description of the Background Art
In a wafer processing system, a lid assembly for a processing chamber is typically rather heavy. To ensure safety for operating personnel, various mechanisms have been used to facilitate the closing or opening of the lid—for example, by reducing the force necessary to effect movement of the lid. In one arrangement, gas springs, or cylinders, are mounted onto a lid assembly to provide a force to assist lifting the lid during opening. Another arrangement uses a spring mechanism which generates a restoring force in response to an external torsional force exerted on the spring during closing or opening of the lid. Typically, a spring is housed inside a hinge-like structure, and is subjected to a torsional force when the lid is opened or closed. This torsional force leads to a compression of the spring, which in turn generates a restoring force resulting in an opposite torsional component. However, the torsional motion in such a mechanism causes particulate contamination due to friction between the spring and its housing. For wafer processing applications, such particulate contamination has to be minimized to avoid decreasing yields on the wafers.
Therefore, there is an ongoing need for alternative counter balance mechanisms which facilitate the opening and closing of lids, while minimizing particulate contamination for wafer processing systems.
SUMMARY OF THE INVENTION
The present invention is a counter balance assembly for a lid assembly. The counter balance assembly (or mechanism) comprises a spring inside a housing assembly which is mounted on a lid of a chamber. When the lid is opened and the counter balance assembly is engaged, an external force is generated which acts along a longitudinal axis of the spring. The external force compresses the spring such that a restoring force is generated. This restoring force increases with increasing lid displacement, and acts in a direction opposite to that of lid displacement.
In one embodiment of the invention, the counter balance assembly is used in a lid assembly for a wafer processing system. The housing assembly is mounted on a lid, which is hingedly mounted over a wafer processing chamber. The housing assembly comprises a top housing member and a bottom housing member, which are connected at a certain distance apart from each other by a screw, which allows relative movement between the two housing members. The top housing member is attached to the lid. When the lid is opened to a predetermined angular displacement, the bottom housing member presses against a chamber wall. An external force is generated such that the bottom housing member is pushed closer to the top housing member, thus compressing the spring inside the housing assembly. A restoring force resulting from the compression of the spring acts in a direction opposite to that of the lid displacement, and reduces the force necessary to keep the lid from falling backwards under its own weight. The use of the counter balance assembly promotes safe operation of the lid assembly by ensuring that the force needed for lid closing stays below a prescribed safety limit.
REFERENCES:
patent: 1930841 (1933-10-01), Miniere
patent: 2046892 (1936-07-01), Blum
patent: 3307734 (1967-03-01), Campbell
patent: 3712248 (1973-01-01), Floehr
patent: 3737947 (1973-06-01), Little
patent: 3906587 (1975-09-01), Little
patent: 4091502 (1978-05-01), Little
patent: 5465862 (1995-11-01), Devlin
Applied Materials Inc.
Newhouse Nathan J.
Thomason Moser & Patterson LLP
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