Electric lamp and discharge devices: systems – Current and/or voltage regulation – Automatic regulation
Reexamination Certificate
2001-03-30
2003-02-04
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
Current and/or voltage regulation
Automatic regulation
C315S219000, C315S224000
Reexamination Certificate
active
06515436
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a discharge lamp lighting apparatus and a lighting appliance employing the same for lighting the discharge lamp in which an inert gas-dominated discharge agent is filled.
BACKGROUND OF THE INVENTION
The inert gas discharge lamp has an advantage of a luminous flux start-up property at a low temperature since in the inert gas discharge lamp the phosphor is emitted by an ultraviolet radiation which is generated by the inert gas discharge and the luminous energy does not depend on the temperature. However, it also has a drawback that the luminous efficiency is lower than that of a mercury-vapor discharge lamp.
On the other hand, the discharge lamp which radiates a visible light by the fluorescent substance layer excited by the ultraviolet radiation generated by the inert gas discharge is improved the luminous efficiency by pulsive-lighting is described in the Japanese Patents, Tokkai-sho 58-135564, Tokkai-Hei 2-174097, Tokko-Hei 8-12794, and Tokkai-Hei 9-199285.
Further, a discharge lamp lighting apparatus having such effects those of the prior arts by applying a high frequency AC voltage whose waveform is adjusted by superposing DC voltages so that a lamp current having a pause period flows across a pair of the electrodes of the discharge lamp, at least one of which is placed on the outer surface of the discharge vessel, is also proposed.
By the way, since a discharge lamp having a pair of the electrodes, in which at least one of the electrodes is placed on the outer surface of the discharge vessel, uses a dielectric barrier discharge, there is a tendency of that generally a starting voltage and a lamp voltage become very high.
Accordingly there is a problem that a high frequency generator breaks down due to the high voltage generated by the high frequency generator itself, if the high frequency generator keeps on operating at a no-loaded state. Further, the insulation of the discharge lamp, a harness wire for feeding power, or a high voltage part of the high frequency generator are easy to be breakdown since the above-described high voltage is applied. When the insulation has been breakdown, it progresses to a serious problem of causing an abnormal discharge.
On the other hand, in the dielectric barrier discharge lamp, it is supplied with a power of a high voltage and a high frequency. Therefore, an abnormal discharge at a high voltage and a high-frequency in different from those of normal discharge occurring between a pair of electrodes in a discharge vessel is relatively easy to occur, even when it is not in a no-load state. Such an abnormal discharge may occur in any of an electrode, a high frequency generator, and a harness connecting the electrode and the high frequency generator with each other. Abnormal discharge at an electrode may also occur in any of between different polarity points and between same polarity points. Abnormal discharge between different polarity points occurs, for example, along the external surface of a discharge vessel. The abnormal discharge between same polarity points occurs in such a case that there is a crack on one electrode. Abnormal discharge at the harness occurs in such as a case when the insulation of the harness is damaged. Abnormal discharge in a high frequency generator occurs in such cases that there are an insulation degradation of an output transformer, an insulation degradation of a high voltage pattern on a printed-wiring board, and a crack or a poor contact at a soldering of a high voltage pin of an output connector.
Once such an abnormal discharge has been occurred, an abnormal discharge occurring region will evolve heat. As a result, there is a danger of that a smoking or a firing may occur at the discharge lamp, the harness, or the high frequency power supply. Furthermore, by such abnormal discharges the near-by materials of abnormal discharge occurring region is degraded, or potentially causes a smoking or firing. Such a smoking or firing must be prevented before it happens.
On the other hand, the Japanese Patent Application Tokkai 2001-15827 which was filed before the present application, but published after the publication of the original application of the present application discloses a technology in that an abnormal discharge detection circuit is provided in a dielectric barrier discharge lamp device for detecting the abnormal discharge based on an electrical behavior of a power supply so as to suspend feeding of a high voltage AC current from the power supply to the dielectric barrier discharge lamp device. However, it is not a particular technology to detect an abnormal discharge of a discharge lamp based on such an electrical behavior of the power supply. By the way, if taking note on FIG.
7
and its associated description in the Tokkai 2001-15827, there is disclosed a circuitry for exclusively extracting the high frequency components
31
in the output amount detection signal detected upon an abnormal discharge so as to suspend the power supply.
That is, the circuitry of the Tokkai 2001-15827 has a resistor
120
for detecting a discharge current connected in series a dielectric barrier discharge lamp and a high pass filter
29
for exclusively extracting the high frequency components
31
in the output amount detection signal detected upon an abnormal discharge from a voltage drop across the resistor
120
. The circuitry has a diode
124
for rectifying the high frequency components
31
outputted from the high pass filter
29
, and an integrator comprised of a capacitor
125
and a resistor
126
for integrating the rectified output so as to extract a fluctuation
34
of the high frequency components
31
. The circuitry also has a comparator
87
for comparing the fluctuation
34
of the output amount detection signal with a preset fluctuation limit
36
. When the fluctuation
34
is higher than the limit
36
, a low level signal
18
which indicates that an abnormal state has been detected is applied to a latch circuit
127
. The latch circuit
127
generates and then holds a low level latch signal in response to the low level signal
18
. In this state, since the output of the comparator
57
cannot pass through a gate
119
, a power supply comes to be suspended.
Also disclosed in FIG.
5
and its associated description of the Tokkai-2001-15827, a circuitry which detects an output voltage of a voltage boosting type chopper DC source
49
for feeding a push-pull type inverter to produce a chopper output voltage signal
52
, and suspends the chopper DC source
49
when the chopper output voltage signal
52
has been off the upper or lower limitation preset for the push-pull type inverter.
That is, the device of the Tokkai 2001-15827 detects an output voltage of the voltage boosting chopper type DC power supply
49
by the diode
50
and capacitor
51
, and generates the chopper output voltage signal
52
. When an excessive electric power has been consumed due to the abnormal discharge and the like, the chopper output voltage signal
52
fails to reach a target defined by a dividing ratio according to two resistors
101
and
102
. In this occasion, the primary clock signal
63
is suspended and thus the power supply is also suspended. Furthermore, in a case of the abnormal discharge whereat a target power fails to be consumed, the primary clock signal
63
fails to be generated, and thus the power supply is also suspended.
Furthermore, the Tokkai-2001-15827 describes that the circuitry of
FIG. 5
may further incorporate therein the resistor
120
, the diode
121
and the abnormal discharge detection circuit
14
, as shown in
FIG. 7
, so that it is possible to deactivate a transistor
106
when the output of the comparator
27
is in a low level, too.
1: Disadvantages in the circuitry of FIG.
7
and its associated descriptions of the Tokkai 2001-15827:
The circuitry can carried out a protection operation if an abnormal discharge is developed even in a no-load state. However, since the protection operation is carried out after that the insulation of the harn
Hara Yoshiaki
Kobayashi Masami
Pillsbury & Winthrop LLP
Toshiba Lighting & Technology Corporation
Vu David
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