Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Filament – electric heater – or resistance in shunt with the...
Reexamination Certificate
2001-05-10
2002-10-22
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Filament, electric heater, or resistance in shunt with the...
C315S049000, C315S050000, C315S066000, C313S037000, C313S341000, C313S271000
Reexamination Certificate
active
06469447
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluorescent lamp lighting apparatus for lighting up a fluorescent light emitting tube using an electronic lighting circuit.
2. Description of the Related Art
In recent years, as energy savings have become more and more important, an increasing number of fluorescent lamp light apparatuses have adopted a high frequency inverter type electronic lighting circuit, instead of a copper-iron stabilizer as conventionally used. Specifically for a light bulb type fluorescent lamp built in the lighting apparatus as an energy-saving light source replacing a light bulb, the use of this type of electronic lighting circuits is becoming more common in order to realize a lamp having a higher lamp efficiency or light emission efficiency and less weight.
In order to improve the lamp efficiency of the electronic lighting circuit for a light bulb type fluorescent lamp, there has been an attempt to improve the circuit conversion efficiency of the electronic lighting circuit. As a result, the circuit conversion efficiency which was about 80% has been increased to a maximum of about 92%. This has been realized by introducing a series inverter circuit system in an electronic light circuit or by using a MOS field emission power transistor as an electronic component. The value of about 92% is almost the maximum possible value for a circuit conversion efficiency. In order to further improve the lamp efficiency, a different new technique, for example, a technique for reducing a power loss caused by heat generation in an electrode filament coil in the fluorescent light emitting tube is demanded.
FIG. 4
is a diagram illustrating a basic structure of a conventional high frequency inverter type electronic lighting circuit
19
(hereinafter, referred to simply as the “electronic lighting circuit
19
”). The electronic lighting circuit
19
includes an Inverter circuit section
25
which is driven by a commercial power supply
13
. The inverter circuit section
25
lights up a fluorescent light emitting tube
20
.
The fluorescent light emitting tube
20
includes a pair of electrode filament coils
21
and
22
. The electrode filament coils
21
includes terminals
21
a
and
21
b
, and the electrode filament coils
22
includes terminals
22
a
and
22
b
. The terminals
21
a
and
22
a
are closet than the terminals
22
b
and
22
b
to the power supply
13
for applying an electric current to the fluorescent light emitting tube
20
.
The terminal
22
a
of the electrode filament coil
22
is directly connected to the inverter circuit section
25
. The terminal
21
b
of the electrode filament coil
21
is connected to the inverter circuit section
25
via an inductor
24
provided for electric current control. The inductor
24
is connected in series to the terminal
21
a
. The terminals
21
b
and
22
b
of the electrode filament coils
21
and
22
are connected to each other via a capacitor
23
. The capacitor
23
and the inductor
24
are included in a resonating circuit. In
FIG. 4
, an inductance of the inductor
24
is represented by “L”, and a capacitance of the capacitor
23
is represented by “Cs”.
The conventional electronic lighting circuit
19
performs an operation for starting and thus placing a fluorescent lamp into a constant lighting state, using a hot cathode starting system. This will be described below.
Before starting the lamp, the inverter circuit section
25
causes an electric current to flow to the electrode filament coils
21
and
22
of the fluorescent light emitting tube
20
through the capacitor
23
in order to pre-heat the electrode filament coils
21
and
22
and thus cause the electrode filament coils
21
and
22
to emit a sufficient amount of thermoelectric. The capacitor
23
is connected parallel to the fluorescent light emitting tube
20
.
When the pre-heating electric current is flown to the electrode filament coils
21
and
22
, a starting voltage is applied between the electrode filament coils
21
and
22
within about 1 second, and thus the fluorescent light emitting tube
20
is started. The starting voltage corresponds to a resonating voltage of the resonating circuit including the capacitor
23
and the inductor
24
.
The fluorescent light emitting tube
20
, after being started, goes into a constant lighting state. In this state, the electric current still flows to the electrode filament coils
21
and
22
via the capacitor
23
, and thus heat is generated in the electrode filament coils
21
and
22
.
As described above, the conventional electronic lighting circuit
19
realizes the constant lighting state of the fluorescent light emitting tube
20
after pre-heating the electrode filament coils
21
and
22
and then starting the fluorescent light emitting tube
20
. After the fluorescent light emitting tube
20
goes into the constant lighting state, the electric current is basically unnecessary. However, since an electric current is required in order to pre-heat the electrode filament coils
21
and
22
by the conventional method using the capacitor
23
, the electric current inevitably flows even after the fluorescent light emitting tube
20
goes into the constant lighting state and thus generates heat in the electrode filament coils
21
and
22
. This heat generation causes a power loss.
In a currently-used light bulb type fluorescent lamp (for example, a 14 W or 25 W light bulb) which has a luminous flux corresponding to that of a general 60 W or 100 W light bulb, the power loss caused by the heat generation is 0.4 W to 0.5 W per electrode filament coil. In the fluorescent light emitting tube
20
, the power loss caused by the heat generation is 0.8 W to 1.0 W per electrode filament coil. These values are not negligible.
FIGS. 5A through 5C
show known electronic light circuits used for reducing such a power loss caused by the heat generation In an electrode filament coil during a constant light state of the fluorescent light emitting tube
20
. Like elements as those in
FIG. 4
bear identical reference numerals.
An electronic light circuit
19
a
shown in
FIG. 5A
adopts a so-called cold cathode starting system. The electrode filament coils
21
and
22
of the fluorescent light emitting tube
20
are respectively shortcircuited by leads
26
and
27
. The leads
26
and
27
are respectively connected parallel to the electrode filament coils
21
and
22
. The fluorescent light emitting tube
20
is started in a cold cathode state with no thermoelectrons being emitted. Due to such a structure, the power lose caused by the heat generation in the electrode filament coils
21
and
22
is reduced.
An electronic lighting circuit
19
b
shown in
FIG. 5B
is disclosed in Japanese Laid-Open Publication No. 10-199686. Diodes
28
and
29
are respectively connected parallel to the electrode filament coils
21
and
22
of the fluorescent light emitting tube
20
. Due to such a structure, the amount of the electric current flowing to each of the electrode filament coils
21
and
22
is reduced to half. Thus, the power loss caused by the heat generation is also reduced to about half.
An electronic lighting circuit
19
c
shown in
FIG. 5C
is disclosed in Japanese Laid-Open Publication No. 5-13186. Capacitors
31
and
32
are respectively connected parallel to the electrode filament coils
21
and
22
of the fluorescent light emitting tube
20
., The capacitor
31
branches the electric current into the capacitor
31
and the electrode filament coil
21
, and the capacitor
32
branches the electric current into the capacitor
32
and the electrode filament coil
22
. Due to such a structure also, the amount of the electric current flowing to each of the electrode filament coils
21
and
22
is reduced. Thus, the power loss caused by the heat generation is also reduced.
Fluorescent lamps are now expected to be used in houses which is one important field of use of light bulbs, in addition to department stores, restaurants, hotels and other business settings
Nakagawa Hiroki
Tahara Tetsuya
Kelly Michael K.
Snell & Wilmer LLP
Vo Tuyet T.
Wong Don
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