Dimmer having a thermally insulated faceplate fastener

Details Dimmer having a thermally insulated faceplate fastener Dimmer having a thermally insulated faceplate fastener

2002-05-10

2004-08-10

Lee, Wilson (Department: 2821)

Electricity: circuit makers and breakers

Electric switch details

Actuators

C200S333000

Reexamination Certificate

active

06774328

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to the fastening of faceplates to heat-dissipating electrical power switching devices, and more particularly, to thermally conductive faceplate fasteners securing faceplates to electrical light dimmers.
BACKGROUND OF THE INVENTION
A typical prior art electrical light dimmer
10
, shown in
FIGS. 1 and 2
, includes a body portion
14
, that is ordinarily mounted in a wallbox
16
, that is recess-mounted in a wall or the like. To give the dimmer a neat, clean appearance, a faceplate
18
, defining a switch opening
20
therein, is usually mounted to the front of the dimmer
10
by means of fasteners
22
, which are most often threaded screws.
The dimmer
10
includes a heat generating device
30
, such as a triac, a field-effect transistor, or the like. In order to dissipate or carry away the heat generated by the heat generating device
30
, the device is often mounted in thermal communication with a yoke
32
having a relatively high thermal conductivity, and is typically made of a metal such as aluminum. In addition to acting as a heat sink for the heat generating device
30
, the yoke
32
also typically functions as a structural element to which is attached the dimmer body portion
14
and the faceplate
18
.
For attaching the faceplate
18
to the yoke
32
with screws
22
, the yoke
32
is usually provided with threaded holes
34
for receiving the screws
22
.
Because the screws
22
are typically made of metal, a thermally conducting material, heat from the heat generating device
30
can be, and often is, transferred from the heat generating device
30
, through the heat sink (or yoke)
32
, to the screws
22
.
In normal operation, this results in the screws
22
having a temperature greater than the ambient temperature of the environment in which the dimmer
10
is located. This poses no danger to any person or object that might come into contact with the screws
22
. However, some people may find undesirable the sensation of faceplate screws
22
that feel warm to the touch. Accordingly, there is a need to provide a means for fastening a faceplate to a dimmer with screws while maintaining the temperature of the screws closer in temperature to the ambient temperature.
SUMMARY OF THE INVENTION
In accordance with the present invention, a dimmer capable of having a faceplate attached thereto by means of fasteners that are thermally insulated from any heat generating devices internal to the dimmer is presented. By thermally insulating the fasteners from any heat generating devices and their associated heat sinks, the faceplate fasteners remain at a temperature closer to that of ambient.
In addition, by thermally insulating the faceplate fasteners from any heat generating devices and heat sinks, the manufacturing of the dimmer can be simplified with a resulting lower manufacturing cost because, for example, there is no longer any need to thread the yoke.
In one embodiment, the dimmer includes a heat dissipating yoke having a first aperture therethrough for allowing the fastener to extend through or past the yoke without contacting the yoke in thermal relationship. The dimmer includes a boss defining a second aperture in axial alignment with the first aperture for receiving the fastener therein. The boss is made of a thermally insulating material, preferably having a thermal conductivity no greater than a predetermined value, such as a thermoplastic, and has a portion that extends through the first aperture to a point flush with a faceplate confronting surface of the yoke.
These and other features and advantages of the present invention will be more readily apparent from the detailed description set forth below taken in conjunction with the accompanying drawings.


REFERENCES:
patent: 4924349 (1990-05-01), Buehler et al.
patent: 4939383 (1990-07-01), Tucker et al.
patent: 5359231 (1994-10-01), Flowers et al.
patent: 6459250 (2002-10-01), Davis
patent: 2003/0089587 (2003-05-01), Mayo et al.

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