Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Discharge device load
Reexamination Certificate
2000-06-20
2001-04-17
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Discharge device load
C315S2090SC, C315SDIG001, C362S260000, C362S221000
Reexamination Certificate
active
06218782
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to electrical lighting assemblies, and more particularly to an improved fluorescent lighting assembly utilizing the fixture for transferring current between electronic ballast and lamp components of the assembly.
BACKGROUND OF THE INVENTION
Fluorescent lighting assemblies are well known and their use has been well established. Conventional fluorescent lighting assemblies, such as the prior art assembly depicted in
FIG. 1
, include a plurality of fluorescent lamps mounted in a lighting fixture, wherein opposite ends of each lamp are electrically connected via conductive wires to one or more electronic ballast subassemblies. Generally, energizing current from the ballast is directed to a first end of each lamp through a first set of wires, and subsequently returned to the ballast from a second end of each lamp through a second set of wires.
As the popularity of fluorescent lighting assemblies has increased in recent years, manufacturers and designers have strived to reduce the costs associated with lighting assembly production. In particular, these efforts have focused primarily on reducing the manufacturing cost of the electronic ballast sub-assembly. Consequently, only limited attention has been directed toward cost reduction of other components of such assemblies.
U.S. Pat. No. 5,907,128 to Altman et al. discloses a fluorescent lighting assembly having a simplified wiring arrangement aimed at reducing the labor associated with installation of the electronic ballast. More specifically, Altman et al. disclose a lighting assembly wherein each lamp has one end connected to a ballast socket, and an opposite second end electrically connected to the second end of an adjacent lamp through a common socket connector. Consequently, the disclosed assembly requires the return of electrical current to the ballast via one of each pair of lamps. Although the assembly disclosed by Altman results in a reduced wiring requirement, it has inherent limitations. For instance, the disclosed assembly incorporates specially designed electrical connectors for electrically shorting the adjacent remote lamp ends. In an alternate embodiment, Altman discloses the use of conventional sockets in lieu of the specially designed connector. However, in that instance connection of adjacent connector pairs requires conventional wiring. A further limitation results from the disclosed electrical configuration in which current is returned to the ballast via the fluorescent lamps. Namely, the required lamp pairing configuration limits the use of the disclosed assembly to mounting an even quantity of fluorescent lamps.
Accordingly, there is a well-established need for a fluorescent lighting assembly having a reduced wiring requirement which overcomes the limitations of known lighting assemblies.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a fluorescent lighting assembly incorporating wireless electronic connection between electronic ballast and fluorescent lamp components of the assembly.
It is another object of the present invention to provide a fluorescent lighting assembly in which current flowing from the ballast to the fluorescent lamps is returned to the ballast via the assembly fixture.
It is a further object of the present invention to provide a fluorescent lighting assembly incorporating electrical circuitry for minimizing the risk of electrical shock during human contact with the assembly, and for minimizing the risk of fire in the event of excessive heating at an electrical connection within the lamp circuit due to a high resistance electrical contact.
These and other objects are achieved by the present invention in which conventional fluorescent lamps
14
, an electrical socket bar
20
, an electronic ballast
30
, and lamp-receiving electrical sockets
28
are mounted on the electrical conductive inner surface
12
of a troffer
11
. Preferably, the lighting assembly
10
is designed for use with conventional off-the-shelf tubular fluorescent lamps having pairs of conventional contact pins
17
,
19
extending from opposite first and second ends
16
,
18
of each lamp.
In the preferred embodiment of the invention, socket bar
20
includes both conventional lamp sockets
22
configured for receiving standard fluorescent lamp contact pins
17
, and ballast sockets
24
for electrically coupling the internal lamp ballasting circuitry to the socket bar. Furthermore, the socket bar preferably includes power supply sockets
26
for electrically coupling input power supply wires
42
to internal ballast wires
31
electrically connected to ballast inverter circuitry
32
. The socket bar
20
is provided with pre-wired electrical connections
25
between the ballast sockets
24
and the lamp sockets
22
. Wire leads
42
extend from one end of the socket bar for connection to an external power supply
40
, such as a conventional source of 120 VAC or 277 VAC power commonly used in lighting circuits, and terminate at ballast power supply sockets
26
.
A second plurality of conventional fluorescent lamp sockets
28
are provided mechanically mounted at an opposite end of the troffer
11
. These lamp sockets
28
are configured and positioned for receiving contact pins
19
extending from the second end
18
of fluorescent lamp
14
. Significantly, each of the lamp sockets
28
is electrically grounded to conductive surface
12
of troffer
11
. In this manner, current traveling through lamp pins
19
is returned to lamp ballasting circuitry
34
contained in electronic ballast
30
via the fixture
10
. Preferably, the sockets are electrically connected in series such that only one lamp socket has to be grounded to the fixture. The directly grounded lamp socket is grounded to the fixture using a self-tapping screw. Alternatively, the sockets
28
can be combined in a unitary structure such as the socket bar
20
mounted at the opposite end of troffer
11
.
Referring now to
FIGS. 3 and 5
, the electronic ballast
30
includes three circuits in tandem; namely, inverter circuitry
32
and lamp ballasting circuitry
34
separated by an isolating transformer
38
. Furthermore, lamp ballasting circuit
34
includes a safety circuit
36
which continuously monitors the lamp circuitry for unusual lamp loads that could lead to an unsafe condition. In particular, safety circuit
36
renders the lamp circuit inoperable in instances where there is simultaneous human contact with exposed lamp pins
19
and the lighting fixture
10
, or where there is an increased load due to a high resistance electrical contact.
Lamp ballasting circuit
34
is electrically grounded to conductive fixture surface
12
. Preferably, electrical grounding is achieved by providing a wire lead (not shown) attached at one end to the ballasting circuit
24
and at an opposite end to an electrically conductive ballast mounting component, such as a metal bolt (not shown), in electrical contact with surface
12
.
The inverter circuitry is conventional and well known in the art. Generally, the standard alternating current (AC) voltage from power supply
40
is rectified and converted to a direct current (DC) voltage, which may be regulated or not. In the preferred embodiment of the present invention, the DC voltage is subsequently applied to a pair of power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs)
54
arranged in a standard half-bridge circuit and driven by a standard off-the-shelf half bridge driver
52
. The output of the half-bridge circuit is preferably on the order of about 35 KHz and is controlled by a setting on the half-bridge driver
52
. This output is coupled to a standard lamp ballasting circuit
34
by an isolating transformer (T
2
)
38
preferably of the ferrite-core type. Isolating transformer
38
electrically isolates the output of the lamp ballast circuit
34
from the input power supply
40
.
Referring now to
FIG. 4
, in an alternate embodiment of the present invention socket bar
20
is eliminated and lamp pins
17
are direct
Gold Glenn E.
Vo Tuyet T.
Wong Don
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