Joints and connections – Distinct end coupler – Interrupted periphery – e.g. – split or segmental – etc.
Reexamination Certificate
1999-05-06
2001-03-06
Kim, Harry C. (Department: 3629)
Joints and connections
Distinct end coupler
Interrupted periphery, e.g., split or segmental, etc.
C403S335000, C403S329000, C359S819000
Reexamination Certificate
active
06196755
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to projection television lens assemblies and, in particular, to a locking device employed in such assemblies.
BACKGROUND OF THE INVENTION
Projection televisions are well known. In general, a projection television set or projector includes three cathode ray tubes (CRTs), corresponding to the primary colors, red, blue, and green. Associated with each of the CRTs is a projection lens assembly, which is comprised of a plurality of optical lens units. Overall, a CRT has an attached faceplate, and the function of the lens assembly is to magnify the image appearing on the faceplate of the CRT, and thereby project it onto a viewing screen, which is much larger than the faceplate of the CRT. For a typical layout of the optical lens units in a projection television lens assembly see U.S. Pat. No. 4,776,681.
An illustrative, prior art lens cell
10
used in a projection television lens assembly is shown in FIG.
1
. Basically, it comprises a plastic tubular member, generally referred to as a lens cell
10
. As shown therein, the lens cell
10
itself is further comprised of two corresponding cell halves
12
and
14
. The lens cell
10
has grooves which hold the optics or the optical lens units. After the optics are mounted within one of the corresponding cell halves, the other of the cell halves is used to lock in the optics. In the past, cantilever snaps, referred to by reference numeral
13
, have been employed to fasten the two cell halves
12
and
14
together, thus ensuring the retention of the optical lens units within the lens cell
10
. The most commonly used cantilever snap design has an undercut molded onto the “male” flexing member for engagement with the “female” component, shown in
FIGS. 1 and 1A
. The cell halves
12
and
14
of the lens cell
10
are assembled together by the use of an assembly fixture that exerts an external force on the cell halves
12
and
14
to engage the cantilever snaps
13
. Upon engagement of the cantilever snaps
13
, the external force is released and the optics within the lens cell
10
react by pushing back on each of the cell halves
12
and
14
. The problem with such a cantilever snap design is that once the optics are mounted within the lens cell
10
, the cantilever snaps
13
are usually constantly under load due to the force F
e
exerted by the optics. As such, the cantilever snap design fails to provide a retention force that opposes the internal force F
e
exerted by the optics, which pushes outwardly against each of the lens cell halves
12
and
14
, tending to separate the cell halves
12
and
14
. Thus, the constant load causes the cantilever snaps
13
to disengage, resulting in a separation of the cell halves
12
and
14
of the lens cell
10
.
An object of the invention is to provide a locking device that ensures retention of the optical lens units within the lens cell. Another object of the invention is to provide a locking device that provides a retention force that opposes the force exerted outward against each of the lens cell halves by the optics within the lens cell. Yet, a further object of the invention is to provide a locking device that can be easily unlocked or disengaged.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a projection television lens assembly that substantially obviates one or more of the limitations and disadvantages of the related art. The present invention provides a solution to the problems described above relating to lens cell assemblies in a projection television. Specifically, the invention provides a locking device for locking two matching lens cell halves of a lens cell.
In accordance with the broadest aspect of the present invention, the invention resides in clips which are located at the joint where the two cell halves mate. The clips, which are molded as part of each cell half, are each comprised of a male member which is inserted into a female member. The male member includes a flexible tab which is deflected when inserted into the female member. After insertion, it is maintained in a deformed state, that is the tab is maintained by the female member so that it is bent from its original position. As a result, a bending moment is induced and maintained in the tab and that moment pushes the tab against an outer wall of the female member. Consquently, forces are established which lock the male member in place. Additionally, the wall of the female member exerts a force on the tab and that force, which is inwardly directed, serves to lock together the two halves and ensures retention of the lens units within the lens cell.
To ensure that the forces described above are properly directed, the surface at the end of the tab and the surface of the female member against which it abuts are appropriately selected. When properly selected, there will be sufficient inwardly directed forces that the cell halves are held together. Specifically, when the angle of the surface of the tab with respect to a radial line through that surface equals &bgr; and &bgr; is appropriately selected, for example about 15°.
The basic construction of the male member includes a wall which extends from the cell half and an inverted flexible portion which is connected to it. The flexible portion is the part which deforms when the male member is inserted into the female member. The angle between the flexible portion of the male member and the wall that extends from the cell half is equal to &thgr;. In particular, &thgr; is appropriately selected, such that, the retention force, F
r
, will be related to the deforming force, F
i
, by the expression F
r
=F
i
Cos (90−&thgr;). In a preferred embodiment, &thgr; is chosen to be approximately 15°. The female member includes an integral tab having an interior surface. The male member is received between the tab and the exterior of cell half to which the tab is connected.
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Okorocha Livyn Obiajuru
Purvis Wilton Ray
Corning Incorporated
Kim Harry C.
Murphy Silvy
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