Television base casting

Details Television base casting Television base casting

2001-07-02

2004-02-10

Wilkens, Janet M. (Department: 3637)

Supports: cabinet structure

Having particular cabinet support

Single pedestal

C312S007200, C348S836000

Reexamination Certificate

active

06688713

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to projection television sets, and more particularly to an integrally weighted base that facilitates structural and operational stability in a projection television enclosure.
BACKGROUND
Projection televisions (PTVs) or “big screen” TVs are a popular alternative to traditional picture tube televisions because they provide comparably larger viewable screens that cannot be efficiently produced using conventional picture tubes. PTV cabinets are presently designed to hold electrical and optical components, as required, to decipher and project a television picture on a screen generally on the front of the cabinet. The most common PTV on the market today projects pictures created via appropriate electrical and optical components onto a mirror within a box containing the entire apparatus so that the picture reflected to a screen is as large as possible for the volume occupied by the cabinet enclosing it. Currently, PTV screens typically range in size from about 45 to about 73 inches along their diagonal, while the cabinets typically range in size from about 48 inches to over 65 inches in height, from about 38 inches to over 65 inches in width, and from about 22 inches to over 29 inches in depth. The cabinets are assembled in an aesthetically appealing manner as required to hold the electrical components, light generator(s), and lenses, mirror and screen in the relationship required to obtain the desired televised picture.
Most PTVs marketed today include a cabinet constructed from multiple pieces of particleboard cut and glued together. Some cabinets also have plastic components held to the basic cabinet structure with screws or other fasteners. The number of plastic components and particleboard pieces needed to form such cabinets typically range in excess of fifty (50) pieces. Because of the size of PTVs, and the particleboard from which the cabinets are typically constructed, PTVs tend to be quite heavy and difficult to maneuver.
Alternative methods of manufacture are available that may reduce the overall weight of these cabinets and the number of components necessary to construct such cabinets. For instance, injection molding could be used to form such cabinets out of plastic. Another alternative would be to vacuum form the cabinetry out of plastic. A further alternative would be to form the cabinet out of molded plastic foam.
The use of lighter weight materials to manufacture PTV cabinets leads to an additional problem in that the newer, light weight cabinets are easier to tip over relative to the traditional particle board cabinets. For example, in addition to being lighter in weight, newer PTV cabinets are also increasingly shallower in depth relative to traditional cabinets. The shallower depth cabinets have a smaller footprint but still generally maintain the same height as traditional PTV cabinets. Consequently, tip over for the newer cabinets becomes more likely when compared with the traditional cabinets.
In order to ensure that they produce PTVs that are not likely to tip over, PTV manufacturers typically strive to meet certain safety standards with respect to PTVs and PTV enclosures. One current standard is the Underwriters Laboratories (“UL”) load standard. The UL load standard requires that a PTV cabinet must be able to withstand 25 lbs of force applied to any extremity of the cabinet without tipping over. Without the addition of some weight to the lower portion of the lighter, shallower PTV cabinets, these cabinets are more likely to fail the UL tip over test when compared with traditional particle board cabinets. To address this problem, those skilled in the art currently add counterweights to the base or lower portions of the lighter weight and shallower cabinets in order to enable these cabinets to withstand at least 25 lbs of force applied to any of their extremities without tipping over. Using one example calculation, the total weight for a PTV cabinet to avoid tip over is determined using the following formula:
Minimum Weight=(25 lbs)(Height of the Cabinet/Depth of the Cabinet).
Turning to
FIG. 1
, a conventional enclosure
10
of a PTV
50
is illustrated. The conventional enclosure
10
includes top
12
, bottom
14
, front
16
, and rear
18
panels. Side panels connecting the front
16
and rear
18
panels are also included, but not illustrated. The conventional enclosure
10
is typically divided by an internal wall
24
into two compartments, i.e., an upper
20
and a lower
22
compartment. Cathode ray tubes (CRTs)
26
and printed wiring boards (PWBs)
30
are typically mounted in the lower compartment
22
, while a mirror M and a screen S are mounted in the upper compartment
20
. At least one projection lens
28
typically extends from the lower compartment
22
into the upper compartment
20
through the internal wall
24
. The upper compartment
20
is typically tightly sealed from the lower compartment
22
to protect the inside of the upper compartment
20
from dust and other foreign materials. The lower compartment
22
typically includes one or more sets of ventilation holes to exhaust heat radiating from the CRTs
26
and the PWBs
30
. As shown, the lower compartment
22
may include a first set of ventilation holes
32
positioned adjacent the top of the lower compartment
22
and a second set of ventilation holes
34
positioned adjacent the bottom of the lower compartment
22
. When the enclosure
10
is made shallower and/or is constructed using lighter weight materials and methods, such as those previously discussed, counterweights
36
are typically positioned in the lower compartment
22
, and normally on top of the bottom panel
14
. The counterweights
36
increase the enclosure's total weight and lower the enclosure's center of gravity. As a result, the counterweights
36
increase the amount of force required to tip over the enclosure
10
. Currently, counterweights
36
, which may be metal, clay, or concrete bricks, additional particle board base pieces, or any other suitable counterweights, are tied or otherwise physically attached to the bottom panel
14
of the enclosure
10
. The number of counterweights
36
used in the cabinet
10
, to enable the enclosure
10
to pass the UL tip over test, may be determined with the aforementioned formula.
The current methods for balancing a shallower, lighter PTV cabinet result in several disadvantages. For example, the use of additional particle board bases to increase the weight and stability of these cabinets often requires the additional use of forest products, thereby contributing to long term environmental deleterious effects. Also, the additional step of adding a separate weight to a cabinet increases the complexity and cost of manufacturing the lighter weight PTV cabinets. There is also a danger that the weights may not be properly secured to the cabinet during construction, thereby resulting in safety issues should the weights become dislodged during transport of the cabinet, or during the lifetime of the cabinet. For example, the weights may become dislodged and repositioned in an area that causes the cabinet to become unbalanced and more likely to tip over.
Those skilled in the art have failed to provide for a light weight PTV cabinet capable of passing standard load tests without the addition of costly counterweights. Thus, it would be desirable to provide for a PTV cabinet or an integrally weighted base suitable for attachment to a PTV cabinet that is easy and less costly to manufacture, mitigates environmental damage by decreasing the reliance on wood as a material for counterweights, is less vulnerable to manufacturing irregularities, and results in a cabinet that meets any applicable load or tip over standards for PTV cabinets.
SUMMARY OF THE INVENTION
The present invention is directed to an integrally weighted base for use with an enclosure to form an integrally weighted PTV cabinet. The base acts to stabilize the cabinet and enables the cabinet to satisfy load and tip over standards. The bas

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