Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Discharge device load
Reexamination Certificate
2003-09-10
2004-08-03
Tran, Thuy Vinh (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Discharge device load
C313S485000, C313S493000
Reexamination Certificate
active
06771024
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the configuration of a fluorescent lamp. In particular, the present invention relates to the configuration of a fluorescent lamp that can achieve a smaller lamp shape for the same lamp characteristics.
BACKGROUND ART
FIG. 10
shows a light-emitting tube
27
used in a conventional compact fluorescent lamp. The light-emitting tube
27
includes two straight glass tubes
32
,
33
. One end of each of glass tubes
32
,
33
is closed, and the other end is sealed with stems
31
for supporting electrodes
29
,
30
, respectively. The glass tubes
32
,
33
are connected at the one end portion by a bridge junction
34
. A discharge space is formed in the light-emitting tube
27
through the bridge junction
34
. A phosphor
28
is applied to the inside surface of each of the glass tubes
32
,
33
. The light-emitting tube
27
is filled with mercury and a buffer inert gas. A resin base
35
is attached to the end of the light-emitting tube
27
on the stem side, thus providing a so-called single-base compact fluorescent lamp as a finished product.
The conventional compact fluorescent lamp as mentioned above has a small lamp shape and is characterized by high efficiency and long life.
For example, a 36W type compact fluorescent lamp as shown in
FIG. 10
, which is a major product for a supply voltage of 200V, has a lamp length of 410 mm. This is about one third of the lamp length (1198 mm) of a 40W type straight fluorescent lamp whose luminous flux is substantially the same as that of the 36W type compact fluorescent lamp. The 36W type compact fluorescent lamp can have the lamp characteristics such as a luminous flux of 2900 lm, a lamp efficiency of 80.5 lm/W, and a lamp life of 9000 hrs. The tube outer diameter of the compact fluorescent lamp is reduced to 20 mm compared with 32 mm for the 40W type straight fluorescent lamp. The discharge path length (i.e., a distance between the electrodes) of the compact fluorescent lamp also is reduced to about 730 mm compared with about 1100 mm for the 40W type straight fluorescent lamp. Both the compact fluorescent lamp and the straight fluorescent lamp have a lamp current of 430 mA.
A 96W type compact fluorescent lamp has a lamp length of 860 mm, which is about one third of the lamp length (2367 mm) of a 110W type straight fluorescent lamp whose luminous flux is substantially the same as that of the 96W type compact fluorescent lamp. The 96W type compact fluorescent lamp can have the lamp characteristics such as a luminous flux of 8600 lm, a lamp efficiency of 89.6 lm/W, and a lamp life of 7500 hrs. The tube outer diameter is 22 mm, and the lamp current is 820 mA.
While the compact fluorescent lamps as mentioned above are made smaller than the conventional straight fluorescent lamps, they are still larger than the incandescent lamps that are almost point light source or high-pressure discharge lamps. A further reduction in size of a compact fluorescent lamp makes it possible to design a smaller lighting fixture that can facilitate light distribution control with high efficiency, which may further improve energy saving and lighting design quality. However, there is a limit to such a reduction in lamp shape of the conventional compact fluorescent lamps because they use a bending or junction process to form a continuous discharge path inside the glass tubes as described above.
Before developing the conventional compact fluorescent lamps, various kinds of light-emitting tube configurations were proposed.
For example,
FIG. 11
schematically shows the configuration of a light-emitting tube used in a so-called internally partitioned lamp (R. G. Young et al., “A compact partition fluorescent lamp,” Lighting Design & Application, May 1980, pp. 38-42). Alight-emitting tube
36
includes a straight glass tube
37
wherein the inside surface is coated with a phosphor. The internal space of the straight glass tube
37
is divided by insulating walls
38
into a plurality of portions so as to provide a continuous discharge path. A pair of electrodes
39
,
40
are located at the ends of the discharge path, respectively. This configuration can achieve a smaller lamp shape.
FIG. 12
schematically shows the configuration of a light-emitting tube used in a so-called multi-arc lamp (Mikiya YAMANE et al., “Shunt mechanism for a discharge tube having two discharge paths,” Journal of the Illuminating Engineering Society, vol. 63, No. 9 (1979), pp. 19-25). In a light-emitting tube
41
, a glass stem
43
is provided at one end of a glass bulb
41
so as to seal and support the end of a glass inner tube
44
. An electrode
45
that functions as a cathode is attached inside the glass inner tube
44
by the glass stem
43
. Two electrodes
46
,
47
that function as an anode are attached near the one end of the glass bulb
42
. This lump is turned on by the application of a direct current, and two discharge arcs are generated between the cathode
45
and each of the anodes
46
,
47
.
FIGS. 13A and 13B
schematically show two configurations of light-emitting tubes used in a multiple-tube fluorescent lamp disclosed by JP 8(1996)-315772 A. Alight-emitting tube
48
in
FIG. 13A
has a double-tube structure in which the necessary portion of an envelope
49
is coated with a phosphor, two external electrodes
50
are provided at the bottom, a transparent inner tube
51
that transmits ultraviolet rays is placed in the envelope
49
, and an internal electrode
52
is provided at the bottom of the transparent inner tube
51
. Alight-emitting tube
53
in
FIG. 13B
has a triple-tube structure in which the necessary portion of an envelope
54
is coated with a phosphor, an external electrode
55
is provided at the bottom, double transparent inner tubes
56
,
57
that transmit ultraviolet rays are placed in the envelope
54
, and an internal electrode
58
is provided at the bottom of the transparent inner tube
56
.
The studies conducted by the present inventors on various compact fluorescent lamps proposed so far with the above configurations show that it is very difficult to make those compact fluorescent lamps commercially available as products. For example, the lamp configuration in
FIG. 11
cannot reliably prevent a so-called discharge crosstalk between adjacent discharge paths that are partitioned by the insulating wall
38
. The lamp configuration in
FIG. 12
cannot easily achieve high efficiency in the lamp characteristics, and also has a limit of providing a smaller lamp shape. The lamp configuration in
FIG. 13A
cannot easily achieve high efficiency in the lamp characteristics. For this configuration, it is more difficult to place the ultraviolet-ray transmitting inner tube
51
in the envelope
49
, the inner tube
51
using a different glass material from that of the envelope
49
. Similarly, for the lamp configuration in
FIG. 13B
, it is much more difficult to place the double inner tubes
56
,
57
in the envelope
54
, the double inner tubes
56
,
57
using a different glass material from that of the envelope
54
.
Therefore, to improve energy saving and lighting design quality by promoting the spread of compact fluorescent lamps, it is a major challenge to find a novel lamp configuration that can achieve a much smaller lamp shape than the conventional technique.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a compact fluorescent lamp that can achieve a much smaller lamp shape without degrading the lamp characteristics and contribute to further improvements in energy saving lighting and lighting design quality.
A fluorescent lamp of the present invention includes two glass outer tubes, a bridge junction, and first glass inner tubes. One end of each of the glass outer tubes is closed, and the other end is sealed with stems for supporting electrodes, respectively. A phosphor is applied to the inside surface of each of the glass outer tubes. The bridge junction connects the glass outer tubes at the other end portion to form a discharge space inside the glass outer tubes. The f
Kondoh Toshifumi
Oga Toshiyoshi
Saitoh Masaru
Sudou Masatoshi
Matsushita Electric-Industrial Co., Ltd.
Merchant & Gould P.C.
Tran Thuy Vinh
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