Electricity: conductors and insulators – Insulators – Special application
Reexamination Certificate
1999-02-22
2001-05-01
Kincaid, Kristine (Department: 2831)
Electricity: conductors and insulators
Insulators
Special application
C174S13800J, C361S742000, C361S758000, C361S770000, C428S034100, C411S546000
Reexamination Certificate
active
06225566
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to spacer arrangements, and more particularly, it is directed to spacers for mounting printed circuit boards, discrete components, fans, etc. and method of making the same.
2. Description of the Prior Art
Electronic devices are present in modern equipment from telecommunications to advanced avionics to medical industries. Society has become accustomed to more innovative and sophisticated electronic products, year after year, and advancements in these products have become common place. Such products or devices may have hundreds or even thousands of electrical components mounted on electronic circuit boards. While each circuit board can accommodate a large number of electronic components such as transistors, semiconductor chips, resistors, capacitors, for example, as more functionality is added to electronic assemblies, several circuit boards may be needed to provide the necessary circuitry for the particular electronic product. In such cases, multiple circuit boards are typically mounted together in a stacked arrangement, one board on top of the other. In addition, there is a need to mount accessory items such as descrete devices, cooling fans etc. on a supporting structure within a cabinet.
Conventional spacers, such as the tubular spacer
12
shown in
FIG. 1
may be used to structurally separate stacked circuit boards or to mount accessory items on a supporting surface. The conventional spacer
12
has a cylindrical shaped body with a bore
14
therethrough and is typically made from a hard plastic material, such as nylon. It comes in a variety of heights to provide the desired amount of board separation. Conventional spacers also readily slide on and off the shaft of a screw. While conventional spacers provide good structural separation support, they are not assembler friendly, as they easily slide off the screw they have been mated with, prior to or during the assembly process. Production time is therefore wasted and the cost of assembling an electronic product increases. When hundreds or thousands of products are being assembled, the increased production can be significant. With the ever-present pressure to drive costs down in order to be competitive in the consumer electronic market other spacers have evolved.
One such spacer is illustrated in
FIG. 2
, in which a screw spacer
16
includes a ribbed inner wall
18
. A screw inserted into the spacer is held therein by the ribs. However, in order to provide the spacer with sufficient rigidity to provide the necessary mechanical separation support, this spacer
16
as with the conventional spacer described above, must be made of hard plastic material. Accordingly, while spacer
16
provides an improvement over the above-described conventional spacers, screws with a wide range of thread diameter tolerances may either be difficult to insert into spacer
16
or slip out of the spacer altogether. As such, there is still a need for a versatile spacer that provides a dependable solution for quick mechanical assembly and reduced assembly time that is simple to manufacture in large quantities. Additionally, it may be desirable to have a spacer arrangement that accommodates a variety of screws with different thread sizes.
SUMMARY OF THE INVENTION
The foregoing mentioned disadvantages are avoided by a spacer made of two different materials, including an outer sleeve portion made of a rigid material and an inner sleeve portion made of softer material. The through-hole of the softer inner sleeve portion is sized to resiliently accept and snugly hold the shaft of a screw inserted therein.
In one preferred embodiment of the spacer, the softer inner sleeve portion through-hole has a plurality of ridges that extend inwardly to resiliently grasp the shaft portion of a screw. The ridges of the softer inner sleeve portion provide a snug fit to the screw with a low insertion force. This allows spacers to be presassembled with screw and remain mated together during handling and assembly. In another preferred embodiment, the outer sleeve portion has a plurality of inwardly projecting ridges and the softer inner sleeve is disposed over the inner surface of the outer sleeve including these ridges. The soft inner sleeve portion disposed on the ridges resiliently holds a screw shaft inserted through the spacer. In both these spacer embodiments, the outer sleeve portion provides the rigid structure of the spacer providing for mechanical separation.
The relative simplicity of these spacer arrangements allows the spacers to be made in large quantities, being suitably adaptable for the variety of screw sizes, tolerances and/or configurations.
The construction and operation of the preferred embodiments of the spacer of the present invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which like components are designated by the same primed reference numbers.
REFERENCES:
patent: 2395785 (1946-02-01), Klingler et al.
patent: 2681378 (1954-06-01), Skwarek
patent: 2936015 (1960-05-01), Rapata
patent: 3362276 (1968-01-01), Gould
patent: 4640639 (1987-02-01), Matsui
patent: 4975008 (1990-12-01), Wagner
Bivar
Jackson Harold L.
Kincaid Kristine
Nino Adolfo
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