Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-03-24
2001-09-04
Gandhi, Jayprakash N. (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S759000, C361S802000, C361S807000, C439S327000, C403S024000
Reexamination Certificate
active
06285564
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to retainer assemblies, and more specifically to circuit board retainer assemblies.
BACKGROUND OF THE INVENTION
Retainer assemblies have been developed for a broad range of applications, such as for reversibly clamping panels and circuit boards attached to the panels within a housing.
With some applications, it is important that the circuit board retainer insulate and dampen the circuit board from shock and vibration. For other applications, an important feature of the circuit board retainer is to effectively transfer heat generated by the circuit board through the panel and to the housing to which the panel is mounted. In these applications, the retainer assembly and the panel are made from heat conductive materials. The heat transfer is effective only between surfaces of the retainer assembly and the housing that are in direct contact, and the amount of heat transfer is directly proportional to the amount of shared surface area. Additionally, the heat transfer is more effective when a greater amount of force is applied between the housing and the retainer assembly.
A problem with prior art retainer assemblies is that they have a discontinuous surface that abuts against the housing slot. The surface is discontinuous because these prior art retainer assemblies have a plurality of wedge components that expand within the housing slot upon engaging an actuator screw that causes the wedge components to slide together. The wedge components form a rough and discontinuous surface that tends to catch against the housing slot as the panel slides into and out of the slot. This makes installation and servicing of the panels within the housing difficult because the panels do not smoothly slide in and out of the housing slots.
Another problem with prior art retainer assemblies is that they distribute heat unevenly because the wedge components form a discontinuous surface having only partial segments in direct contact with the housing assembly. This can cause the panel to have a discontinuous heat distribution pattern which can adversely effect electronic circuitry attached to the panel.
Still another drawback with prior art retainer assemblies is that they are not self contained when attached to a panel. Prior art retainer assemblies have a plurality of individual components that are interconnected but which are not encased by a housing or analogous structure. Accordingly, if a prior art retainer assembly is damaged and its individual components become disengaged, the components will be free to move about within the housing. Additionally, prior art retainer assemblies can become disengaged if the actuator screw is unscrewed too much. Again, the components will be free to move about within the housing. In either of the above scenarios, the disengaged retainer assembly components may disrupt the operation of the circuit boards within the housing.
There is therefore a need for a retainer assembly that, when attached to a panel and placed in a slot in a housing, provides a smooth and continuous surface that allows the panel to slide freely in and out of the housing. There is also a need for a retainer assembly that provides a more uniform heat transfer surface when abutted against the housing slot. There is also a need for a retainer assembly that is self-contained such that, if damaged, the components are not free to move out of the assembly. Finally, there is a need for a retainer assembly that has a mechanism to prevent it from accidentally disassembling.
SUMMARY
The invention satisfies this need. The invention is a retainer assembly adapted to attach to a panel that reversibly mounts within a housing slot. The retainer assembly has an elongated guide rail having a slot abutment wall. The slot abutment wall has a continuous external surface and an opposed internal surface. The retainer assembly includes an expansion assembly having a forward wail and a rearward wall. The forward wall is spaced apart from the rearward wall of the expansion assembly by a width. The forward wall of the expansion assembly is disposed proximate to the internal surface of the guide rail. The rearward wall of the expansion assembly includes means for attaching the rear wall to a panel that is adapted to having a circuit board attached thereto. The retainer assembly further comprises an expansion actuator for alternatively expanding and contracting the width between the forward wall and the rearward wall of the expansion assembly.
In a preferred embodiment, two retainer assemblies are attached to a panel with the rearward wall of the expansion assembly disposed in abutment with the panel. The panel is slid into a housing slot with the external surface of the guide rail disposed proximate to the housing slot. The panel can be firmly retained within the housing slot by expanding the width between the forward wall and the rearward wall of the expansion assembly until the external surface of the slot abutment wall of the guide rail is pressed tightly against the housing slot.
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Article entitled “Camioc Fastener Technology Sets New Standards for P.C. Board Access” from P.C. Board Fasteners, Selector Guide (date unknown).
Anderson Denton L.
Gandhi Jayprakash N.
Keystone Electronics Packaging, Inc.
Sheldon & Mak
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