Self-ballasted fluorescent lamp

Details Self-ballasted fluorescent lamp Self-ballasted fluorescent lamp

2002-09-10

2004-04-27

Vo, Tuyet T. (Department: 2821)

Electric lamp and discharge devices: systems

Periodic switch in the supply circuit

Silicon controlled rectifier ignition

C315S2090SC, C315S291000, C315S224000

Reexamination Certificate

active

06727661

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to self-ballasted fluorescent lamps.
Fluorescent lamps, which have lower power consumption and a longer life than light bulbs, have become the subject of interest in recent years as energy-efficient light sources for homes and hotels, for example, because they are better for the global environment and more economic, and the ease with which they can be used as a substitute for light bulbs in lighting fixtures employing light bulbs without requiring any changes has lead to their increasingly widespread use.
Moreover, in addition to conventional self-ballasted fluorescent lamps with electrodes, electrodeless self-ballasted fluorescent lamps have recently also started to become widespread. Because they lack electrodes, electrodeless fluorescent lamps have a 5 to 10 times longer lamp life than fluorescent lamps with electrodes, which are the major factor that determines the lamp life in conventional fluorescent lamps with electrodes, and as a result they are expected to become even more widespread in the future.
To produce the most suitable lighting environment to correspond to the TPO, light is dimmed using the light bulb. A light bulb is normally dimmed through the use of a light bulb dimmer that controls the phase of the alternating current commercial power source in order to control the power that is input to the light bulb and change the brightness. However, when a self-ballasted fluorescent lamp is connected to an ordinary light bulb dimmer, there is a significant increase in the current that is input to the self-ballasted fluorescent lamp compared to when it is not connected to a light bulb dimmer, so that when the light bulb dimmer is operated the current may increase twofold or more.
Therefore, when a self-ballasted fluorescent lamp is connected to a light bulb dimmer, the stress on the electric components due to this increase in input current can significantly shorten the life of the ballast circuit.
This makes it difficult to ensure the reliability of a self-ballasted fluorescent lamp when it is inserted into the socket of a lighting fixture provided with a light bulb dimmer and used, and thus there is a need for technology to solve this problem.
A prior art related to this issue is disclosed in JP H09-129383A, which reports a discharge lamp ballast circuit device and a small scale discharge lamp including this circuit device. In its ballast circuit for operating the discharge lamp, the circuit device is provided with a means for detecting that the current input to the ballast circuit is a periodic current pulse that has a larger amplitude than the applied value, and with a means for blocking the supply of power to the ballast circuit based on the signal detected from said detection means.
FIG. 6
shows the circuit device of the discharge lamp disclosed in JP H09-129383A. As shown in
FIG. 6
, the circuit device disclosed therein is provided with a rectifier circuit D
1
to D
4
, a storage means constituted by a capacitor C
2
joined to the rectifier circuit D
1
to D
4
, a DC/AC converter III for converting DC power from the rectifier circuit D
1
to D
4
into AC power and supplying it to a lamp LA, a means I(R
1
to R
6
, T
1
, T
2
, C
1
) for detecting a periodic current pulse that has a larger amplitude than an applied value W
1
, and a means II(IIA, S
1
) joined to the means I, which alters/stops the state of operation of the circuit device.
When a power source is connected between K
1
and K
2
, the voltage from the rectifier circuit, which is constituted by a resistor R
7
and a diode bridge made of diodes D
1
to D
4
, is smoothed out by the capacitor C
2
and the direct current from the capacitor C
2
is converted into alternating current at the DC/AC converter III and supplied to the lamp LA. If this circuit device were carelessly or otherwise connected to a commercial power source via a light bulb dimmer, then a pulse current with a larger amplitude than if it were not connected via the dimmer would flow periodically. As a consequence of this large amplitude pulse current, the amplitude of the voltage pulse generated in the resistor R
6
is increased, the transistor T
2
becomes conducting in response to the signal from the resistor R
6
, and as a result the transistor T
1
also becomes conducting and the capacitor C
1
is charged by the auxiliary power source (not shown), which is connected to the K
3
, via the resistor R
3
and the transistor T
1
. The charge in the capacitor C
1
is discharged through the resistor R
4
, however, if the current pulse is larger than the given value W
1
, the amount of charge that is charged from the auxiliary power source via the terminal K
3
is larger than the amount of charge that is discharged via the resistor R
4
, and as a result the voltage is stepped up at both ends of the capacitor C
1
and reaches the value for activating the circuit portion IIA of the means II. When this occurs, the circuit portion IIA puts the switching element S
1
into an off state, and supply of the voltage is blocked.
However, with the circuit device shown in
FIG. 6
, even if the fact that the circuit device has been connected to the light bulb dimmer is detected by the means I for detecting periodic current pulses and the switching element S
1
subsequently is turned off, there is a risk that the switching element S
1
cannot be maintained (latched) in an off state. In other words, even if the switching element S
1
is turned off, power is necessary to latch the switching element S
1
in an off state, and if the auxiliary power source is provided at a stage after the rectifier circuit D
1
to D
4
, then the voltage of the auxiliary power will gradually decrease because the line for supplying power to the auxiliary power source is blocked after the switching element S
1
is turned off, and thus it is conceivable that the switching element S
1
will eventually turn back on. The switching element S
1
will then be repeatedly turned on and off, which will cause the lamp LA to repeatedly flicker. The auxiliary power source would be able to latch the switching element S
1
in an off state if a rectifier circuit D
1
to D
4
other than the output power portion of the rectifier circuit D
1
to D
4
were provided, however, such a configuration would increase the size of the circuit device and would also be disadvantageous in terms of cost.
Also, the circuit device disclosed in JP H09-129383A is configured so that the supply of power to the circuit is always blocked when a self-ballasted fluorescent lamp has been inadvertently connected to a lighting fixture provided with a light bulb dimmer. In the case of a home, however, if the fluorescent lamp could continue to be operated at a maximum level of the dimmer, that is, without being dimmed, even if the lamp were used in this way, a new lighting fixture would not have to be purchased, which is preferable not only in terms of convenience but is also economical.
Also, when a self-ballasted fluorescent lamp does not operate because it has been inadvertently connected to a lighting fixture that is provided with a light bulb dimmer, a lamp that makes it clear to the user whether it is not operated because it has burnt out or because it has been connected to a light bulb dimmer is desirable.
SUMMARY OF THE INVENTION
The present invention is for solving these problems, and provides a self-ballasted fluorescent lamp provided with a function for operating normally when the self-ballasted fluorescent lamp is inadvertently connected to a lighting fixture provided with a light bulb dimmer if the dimmer is at the maximum level, and for detecting an increase in input current and reliably stopping operation of the ballast circuit if the dimmer is in a dimmed state, so as to latch the lamp in an unlit state and protect the ballast circuit.
It is a further object of the present invention to provide a self-ballasted fluorescent lamp capable of displaying via a display element, so that when the self-ballasted fluorescent lamp is inadvertently connected to a light

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