Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Electric switch inside evacuated or gas filled envelope
Reexamination Certificate
2000-05-02
2001-11-13
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Electric switch inside evacuated or gas filled envelope
C315S071000, C315S074000, C315S106000
Reexamination Certificate
active
06316878
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electric-light bulb, more precisely relates to an electric-light bulb, which is capable of automatically adjusting an electric current passing through a filament.
A conventional electric-light bulb is shown in
FIGS. 7A and 7B
. A base
52
is provided to a glass bulb body
54
. A pair of lead lines
56
a
and
56
b
are provided in the bulb body
54
and vertically extended from a pitch
58
with a separation. A filament
60
is spanned between upper ends of the lead lines
56
a
and
56
b
. The base
52
acts as terminals for supplying an electric current to the lead lines
56
a
and
56
b.
When the electric current is supplied to the lead lines
56
a
and
56
b
via the base
52
, the filament
60
is red-heated by the electric current supplied and radiates light, so that the electric-light bulb
50
is turned on.
In the room temperature, resistance of the filament
60
is low, so an inrush current, which is 13-16 times as great as a rated current, instantaneously passes through the filament
60
when the electric-light bulb
50
is turned on. By turning on and off the electric-light bulb
50
, a great load is applied to the filament
60
, so that a span of life of the electric-light bulb
50
must be shorter.
In the case of an electric-light bulb which is used at a place where the electric-light bulb cannot be easily exchanged, etc. and which must have a long span of life, a resistance (not shown) is provided in a bulb body and connected to a filament in series so as to limit intensity of electric current passing through the filament. Further, a thermistor, whose resistance is reduced when temperature of the filament rises, is provided so as to limit the inrush current passing through the filament.
The conventional electric-light bulbs, which include various types of bulbs in which filaments radiate light, are used for decorating show windows, Christmas trees, etc. and calling people's attention at construction sites, etc. Further, in some cases, a plurality of electric-light bulbs are connected and automatically turned on and off.
To automatically turned on and off the electric-light bulb, a bimetal element is provided in a bulb body and connected to a filament in series. The bimetal elements turns on and off the electric-light bulb as a thermoswitch.
In an initial state, temperature in the bulb body is low, so contact points of the thermoswitch are closed by the bimetal element. An electric current can be supplied to the filament.
When the filament radiates heat and temperature of the bimetal element reaches prescribed temperature, the contact points are opened, so that the electric current passing through the filament is stopped.
By stopping the current supply, the temperature in the bulb body gradually goes down, then the contact points are closed again and the electric current can be supplied to the filament again.
By repeating above described actions, the electric-light bulb can be automatically turned on and off.
However, the conventional electric-light bulb has following disadvantages.
Firstly, in the case of the electric-light bulb having the thermistor for limiting the inrush current, manufacturing cost must be increased because the thermistor is expensive.
Secondly, in the case of using the electric-light bulbs for decorating windows, etc. and calling attention, the conventional electric-light bulbs can be merely turned on and off. These days, electric-light bulbs, which is capable of changing brightness, are required so as to more effectively decorating or calling attention. But the conventional electric-light bulbs cannot automatically change their brightness.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electric-light bulb capable of automatically control an electric current passing through a filament so as to limit an inrush current.
Another object of the present invention is to provide an electric-light bulb capable of automatically periodically changing brightness.
To achieve the objects, the present invention has following basic structures.
A first basic structure of the electric-light bulb of the present invention comprises:
a bulb body;
a filament being provided in the bulb body;
a resistance being provided in the bulb body, the resistance being connected to the filament in series; and
a thermoswitch being provided in the bulb body, the thermoswitch being connected to the resistance in parallel, the thermoswitch including a bimetal element and contact points,
wherein the bimetal element is deformed by heat radiated from the filament and closes the contact points when temperature of the bimetal element reaches prescribed temperature so as to short the resistance.
With this structure, the temperature of the bimetal element is low and the contact points of the thermoswitch are closed when the electric-light bulb is turned on. Namely, the resistance, which is connected to the filament in series, is not shorted, so an inrush current can be limited. By limiting the inrush current, a span of life of the electric-light bulb can be extended. Since the resistance is not shorted, a brightness of the electric-light bulb is low. When the temperature in the bulb body reaches the prescribed temperature, the resistance is shorted by the bimetal element, so that the brightness of the electric-light bulb is made higher. After the brightness is made higher, the high Brightness State can be continued as far as the electric current is supplied. The bimetal element is inexpensive, so manufacturing cost of the electric-light bulb can be reduced.
A second basic structure of the electric-light bulb of the present invention comprises:
a bulb body;
a filament being provided in the bulb body;
a resistance being provided in the bulb body, the resistance being, connected to the filament in series; and
a thermoswitch being provided in the bulb body, the thermoswitch being, connected to the resistance in parallel, the thermoswitch including a bimetal element and contact points,
wherein the bimetal element is deformed by heat radiated from the filament and opens the contact points when temperature of the bimetal element reaches prescribed temperature so as to reduce an electric current passing through the filament by the resistance, and
wherein the bimetal element returns to an initial state and recloses the contact points after the contact points are opened and the heat radiated from the filament is reduced.
With this structure, the contact points of the thermoswitch are closed until the temperature in the bulb body reaches the prescribed temperature, so that the resistance is shorted and the electric current is supplied to the filament. Thus, the brightness of the electric-light bulb is made high. When the temperature of the bimetal element reaches the prescribed temperature, the bimetal element deforms and opens the contact points. By opening the contact points, the electric current passing through the filament is limited by the resistance, so that the brightness of the electric-light bulb is made lower. By limiting the current passing through the filament, the temperature in the bulb body goes down. When the temperature reaches to the prescribed temperature, the bimetal element returns to an initial state, so that the contact points are closed again and the brightness of the electric-light bulb is made high again.
The current passing through the filament can be automatically periodically changed, so that the electric-light bulb can alternately change the brightness. With this action, the electric-light bulb can effectively decorate windows, etc. and effectively call attention. Since the current intensity is always changed, the filament is not overloaded and a durability of the electric-light bulb can be improved.
A third basic structure of the electric-light bulb of the present invention comprises:
a bulb body;
a filament being provided in the bulb body;
a resistance being provided in the bulb body, the resistance being connected to the filament in series;
a first thermoswitch bei
Birch & Stewart Kolasch & Birch, LLP
Philogene Haissa
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