Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Silicon controlled rectifier ignition
Reexamination Certificate
2001-06-14
2003-04-22
Le, Hoanganh (Department: 2821)
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Silicon controlled rectifier ignition
C315S169300
Reexamination Certificate
active
06552497
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to alight bulb type fluorescent lamp lighting apparatus for lighting up a fluorescent light emitting tube using a high frequency inverter type 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.
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 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
119
(hereinafter, referred to simply as the “electronic lighting circuit
119
”). The electronic lighting circuit
119
includes an inverter circuit section
125
which is driven by a commercial power supply
113
. The inverter circuit section
125
lights up a fluorescent light emitting tube
120
.
The fluorescent light emitting tube
120
includes a pair of electrode filament coils
121
and
122
. The electrode filament coil
121
includes terminals
121
a
and
121
b,
and the electrode filament coil
122
includes terminals
122
a
and
122
b.
The terminals
121
a
and
122
a
are closer than the terminals
121
b
and
122
b
to the power supply
113
for applying an electric current to the fluorescent light emitting tube
120
.
The terminal
122
a
of the electrode filament coil
122
is directly connected to the inverter circuit section
125
. The terminal
121
a
of the electrode filament coil
121
is connected to the inverter circuit section
125
via an inductor
124
provided for electric current control. The inductor
124
is connected in series to the terminal
121
a.
The terminals
121
b
and
122
b
of the electrode filament coils
121
and
122
are connected to each other via a capacitor
123
. The capacitor
123
and the inductor
124
are included in a resonating circuit. In
FIG. 4
, an inductance of the inductor
124
is represented by “L”, and a capacitance of the capacitor
123
is represented by “Cs”.
The conventional electronic lighting circuit
119
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
125
causes an electric current to flow to the electrode filament coils
121
and
122
of the fluorescent light emitting tube
120
through the capacitor
123
in order to pre-heat the electrode filament coils
121
and
122
and thus cause the electrode filament coils
121
and
122
to emit a sufficient amount of thermoelectrons. The capacitor
123
is connected parallel to the fluorescent light emitting tube
120
.
When the pre-heating electric current is supplied to the electrode filament coils
121
and
122
, a starting voltage is applied between the electrode filament coils
121
and
122
within about 1 second, and thus the fluorescent light emitting tube
120
is started. The starting voltage corresponds to a resonating voltage of the resonating circuit including the capacitor
123
and the inductor
124
.
The fluorescent light emitting tube
120
, after being started, goes into a constant lighting state. In this state, the electric current still flows to the electrode filament coils
121
and
122
via the capacitor
123
, and thus heat is generated in the electrode filament coils
121
and
122
.
As described above, the conventional electronic lighting circuit
119
realizes the constant lighting state of the fluorescent light emitting tube
120
after pre-heating the electrode filament coils
121
and
122
and then starting the fluorescent light emitting tube
120
. After the fluorescent light emitting tube
120
goes into the constant lighting state, the electric current for heating the electrode filament coils
121
and
122
is basically unnecessary. However, since an electric current is required in order to pre-heat the electrode filament coils
121
and
122
by the conventional method, the electric current inevitably flows even after the fluorescent light emitting tube
120
goes into the constant lighting state and thus generates heat in the electrode filament coils
121
and
122
. 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
120
, 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
120
. Like elements as those in
FIG. 4
bear identical reference numerals.
An electronic light circuit
119
a
shown in
FIG. 5A
adopts a so-called cold cathode starting system. The electrode filament coils
121
and
122
of the fluorescent light emitting tube
120
are respectively shortcircuited by leads
126
and
127
. The leads
126
and
127
are respectively connected parallel to the electrode filament coils
121
and
122
. The fluorescent light emitting tube
120
is started in a cold cathode state with no thermoelectrons being emitted. Due to such a structure, the power loss caused by the heat generation in the electrode filament coils
121
and
122
is reduced.
An electronic lighting circuit
119
b
shown in
FIG. 5B
is disclosed in Japanese Laid-Open Publication No. 10-199686. Diodes
128
and
129
are respectively connected parallel to the electrode filament coils
121
and
122
of the fluorescent light emitting tube
120
. Due to such a structure, the amount of the electric current flowing to each of the electrode filament coils
121
and
122
is reduced to half. Thus, the power loss caused by the heat generation is also reduced to about half.
An electronic lighting circuit
119
c
shown in
FIG. 5C
is disclosed in Japanese Laid-Open Publication No. 5-13186. Capacitors
131
and
132
are respectively connected parallel to the electrode filament coils
121
and
122
of the fluorescent light emitting tube
120
. The capacitor
131
branches the electric current into the capacitor
131
and the electrode filament coil
121
, and the capacitor
132
branches the electric current into the capacitor
132
and the electrode filament coil
122
. Due to such a structure also, the amount of the electric current flowing to each of the electrode filament coils
121
and
122
is reduced. Thus, the power loss caused by the heat generation is also reduced.
Fluorescent lamps a
Nakagawa Hiroki
Tahara Tetsuya
Le Hoang-anh
Snell & Wilmer LLP
Tran Chuc D
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