Compact fluorescent lamp and method for manufacturing

Details Compact fluorescent lamp and method for manufacturing Compact fluorescent lamp and method for manufacturing

1998-12-04

2002-11-26

Patel, Vip (Department: 2879)

Electric lamp and discharge devices

With luminescent solid or liquid material

With gaseous discharge medium

C313S485000

Reexamination Certificate

active

06486598

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to a compact fluorescent lamp and a method for manufacturing such lamp and more particularly, relates to a compact fluorescent lamp that can be fabricated by adhesively bonding planar glass plates together forming a hermetically sealed chamber having interior partitions therein dividing a chamber cavity into a plurality of sub-chambers with fluid communication thereinbetween such that a maximum length of passageway for an electrical discharge may be achieved resulting in an improved brightness of the lamp, and a method for manufacturing such lamp.
BACKGROUND OF THE INVENTION
Fluorescent lamps that utilize a fluorescent coating in a glass tube and a gas filling capable of being charged to produce ultraviolet energy in order to energize the fluorescent coating have been used for a long time. The conventional fluorescent lamps are normally supplied in the form of elongated tubes of significant length, for instance, between 2 ft and 4 ft, that require a large installation space and large fixtures for holding such lamps. Due to the bulkiness of the lamps and the fixtures, conventional fluorescent lamps have only been used in industrial or commercial applications where available space for installation is not a problem. The consumer or home usages of the fluorescent lamps are limited to the 1 ft length lamps normally used in a reading lamp fixture, or the 4 ft lamps normally used in a shop light fixture. The energy saving aspect of the fluorescent lamps has therefore not been fully utilized in the consumer market, mainly due to its bulkiness and its low light intensity (or low lumen output), when the lamps are fabricated in a package that is small enough to fit inside a consumer-type light fixture.
In more recent years, there is a significant push for the use of more compact fluorescent lamps for replacing the conventional incandescent lamps caused by a high awareness of energy savings. One other benefit for using the fluorescent lamps is the longer life time of the lamps when compared to the incandescent lamps. More compact fluorescent lamps became available which are shaped in a plurality of parallelly extending tubes from a base at a predetermined length.
One obvious drawback of the compact fluorescent lamps that must be overcome before the lamps can be widely used in the consumer market is the low lumen output when compared to that from the incandescent lamps. For instance, in a conventional 20 watt straight tube fluorescent lamp which produces approximately the same lumen output as a 100 watt incandescent bulb, 4 ft length of the fluorescent lamp is required. This is the type of straight tube fluorescent lamps that are normally used in shop light fixtures. In order to produce a higher lumen output, the arc discharge length (or simply known as the discharge length), required for producing such lumen output must be maximized which leads to the problem of packaging a long tube within a small package size such that it fits in a conventional incandescent lamp fixture.
Lamp manufacturers have extended the length of the respective tube portions in a lamp envelope, or alternatively increased the number of the tube portions to as many as eight such tube portions arranged side-by-side. One example of such application produced fluorescent lamps by bending segments of glass tubings into U-shapes and sealing of one or both legs and then connecting two or more of such bent tubes with glass bridges by simultaneously blowing out a small hole near one end of the tube and then fusing them together. For instance, in a dual U-shaped lamp, the arc discharge passageway goes up one leg, down the other and then through the glass bridge into a second bent tube arrangement.
One of such designs for fluorescent lamps is shown in U.S. Pat. No. 5,252,890 and in FIGS.
1
A~
2
B. FIGS.
1
A~
1
B shows a compact type fluorescent lamp device that has a crooked arc path. A reversed W-shaped arc bulb
10
which includes a first U-shaped bulb
12
and a second U-shaped bulb
14
. The reverse W-shaped arc bulb
10
is fabricated in the following manner. First, the outside surface of one of the ends
16
of the first U-shaped bulb
12
and the corresponding surface of one of the ends
18
of the second U-shaped bulb
14
are heated. The heated portions are closely opposed and connected to one another in a blow-off process to fluidly communicate to each other. As shown in
FIG. 1B
, a first electrode
20
is disposed in one end
22
of the first U-shaped bulb
12
, and a second electrode
24
is arranged in the other end
26
. A substantially W-shaped arc path is thus formed in the connected first and second U-shaped bulbs
12
and
14
.
As shown in
FIG. 1B
, a wide recess
28
is formed at the center of the pedestal portion
30
of the base
32
. To house the connected portion of the first and second U-shaped bulbs
12
and
14
. The process further requires the formation of a pair of holes
32
and
34
at the opposite sides of the wide recess
28
in the pedestal portion
30
. The other ends
22
and
26
of the first and second U-shaped bulbs
12
and
14
in which the first and second electrodes
20
and
24
are disposed are respectively inserted into the corresponding holes
32
and
34
, and are further supported with an elastic bonding agent which is later filled in the pedestal portion
30
. The reversed W-shaped arc bulb
10
therefore requires elaborate manufacturing steps for blowing-off portions of the glass tubes and then reconnecting them to provide fluid communication between the two U-shaped bulbs. It is an expensive manufacturing process and the product produced must be marketed at a high cost basis.
In another embodiment, also disclosed in U.S. Pat. No. 5,252,890, a first, second, third and fourth straight bulbs
36
,
38
,
40
and
42
are rectangularly arranged on pedestal portion
30
of the base
32
extending perpendicularly from the pedestal portion
30
. The extended end portion
36
a
of the first bulb
36
is connected to the extended end portion
38
a of the second bulb
38
by a first connecting tube
44
to provide fluid communication between the two bulbs. This is shown in FIG.
2
B. The base portion
36
b
of the first bulb
36
is disposed in a first hole
46
a
formed in the pedestal section
30
of the base
32
. The base end portion
38
b
of the second bulb
38
which is opposite to the extended end portion
38
a
is disposed in a second hole
46
b
formed in the pedestal portion
30
. The inner side surface of the second bulb
38
, facing the third bulb
40
, in the vicinity of base end portion
38
b
is connected to the corresponding portion of the third bulb
40
by a second connecting tube
48
. This is shown in FIG.
2
B. The second bulb
38
and the third bulb
40
are thus in fluid communication with each other. The extended end portion
40
a
of the third bulb
40
is connected to the corresponding portion
42
a
of the fourth bulb
42
by a third connecting tube
50
to enable fluid communication with each other. The base end portion
40
b
of the third bulb
40
is disposed in a third hole
46
c
formed in the pedestal portion
30
, while the base end portion
42
b
of the fourth bulb
42
is disposed in a fourth hole
46
d
in the pedestal portion
30
. A first electrode
52
is supported in the base end portion
36
b
of the first bulb
36
, and a second electrode
54
is supported in the base end portion
42
b
of the fourth bulb
42
. A relatively long arc path is therefore established through the first bulb
36
, the first connecting tube
44
, the second bulb
38
, the second connecting tube
48
, the third bulb
40
, the third connecting tube
50
and the fourth bulb
42
.
In this conventional construction of multiple-tube design, three separate passageways must be provided in connecting the four tubes together such that a single arc path can be obtained. The building of the four individual tubes and the connections must be made thereinbetween render the manufacturing process difficult and costly.

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