Electric lamp and discharge devices: systems – Condenser in the supply circuit – Electric switch in the condenser circuit
Reexamination Certificate
2000-02-29
2001-02-20
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
Condenser in the supply circuit
Electric switch in the condenser circuit
C315S177000, C315S225000, C315S243000, C315S283000
Reexamination Certificate
active
06191538
ABSTRACT:
The invention relates to a high-pressure discharge lamp having a base at one end in accordance with the preamble of patent claim
1
.
I. PRIOR ART
Such a high-pressure discharge lamp is disclosed, for example, in the international patent application having the publication number WO 98/53647. This laid-open patent application describes a high-pressure discharge lamp having a base at one end and a pulse starting device arranged in the base. Accommodated additionally in the base is at least one radio interference suppression reactor which is connected via a supply lead to a gas discharge electrode of the high-pressure discharge lamp. One of these supply leads is constructed as a return conductor led back to the base from the end of the discharge vessel remote from the base. This return conductor runs outside the lamp vessel and has in part no electric insulation. The high voltage required to start the gas discharge in the discharge vessel is fed to the high-pressure discharge lamp, for safety reasons, via the supply lead near the base, which lead is completely surrounded by the lamp vessels or by the base. The gas discharge electrode remote from the base is connected to the frame potential via the return conductor during operation of the lamp so that no high electric voltages occur on the return conductor, which is only partially electrically insulated, during the operation of the lamp.
However, high electric voltages do occur during the starting phase in the radio interference suppression reactors, which serve to suppress radio interference of the lamp current. As a result, high-voltage pulses of up to 6 kV are applied, in particular, to the insufficiently electrically insulated return conductor during the starting phase, despite its connection to the frame potential.
II. SUMMARY OF THE INVENTION
It is the object of the invention to provide a high-pressure discharge lamp having a base at one end and a starting device integrated in the base, which ensures a substantial reduction in the voltage present on the return conductor during the starting phase.
According to the invention, this object is achieved by the characterizing features of patent claim
1
. Particularly advantageous designs of the invention are described in the subclaims.
The high-pressure discharge lamp having a base at one end according to the invention has a base with at least two electric terminals for supplying voltage to the high-pressure discharge lamp, and a discharge vessel which is sealed at both ends and has a sealed end near the base and a sealed end remote from the base. Enclosed in the discharge vessel is an ionizable filling for producing a light-emitting gas discharge. Moreover, at least one radio interference suppression reactor and a starting device for starting a gas discharge in the discharge vessel are arranged in the base. Furthermore, the high-pressure discharge lamp according to the invention has at least two gas discharge electrodes arranged inside the discharge vessel, at least one first gas discharge electrode being connected to one first electric terminal of the high-pressure discharge lamp via a return conductor led out from the end remote from the base and via the at least one radio interference suppression reactor, and at least one second gas discharge electrode being connected to a second electric terminal of the high-pressure discharge lamp by means of a supply lead led out from the end near the base. According to the invention, the return conductor is connected to the second electric terminal of the high-pressure discharge lamp via a bidirectional trigger arranged in the base, and the first electric t erminal is connected to the second electric terminal of the high-pressure discharge lamp via the at least one radio interference suppression reactor and via the bidirectional trigger. The bidirectional trigger advantageously makes thermal contact with a heat sink.
The voltage drop across the return conductor during the starting phase is limited to at most 1 kV by the abovementioned features according to the invention, thus avoiding electric flashovers from the return conductor onto electrically conducting components arranged in the environment, in particular onto the metallized reflector surface, and, furthermore, thus preventing damage owing to voltage overloading of the operating unit connected to the high-pressure discharge lamp. It is advantageous to make use as bidirectional trigger of a varistor or a bidirectional diode circuit, since these components are particularly suitable for high voltages and high currents. If the breakdown voltage of these components is exceeded, they can convert into heat the electric energy released, even in the case of relatively high short-circuit currents. The bidirectional diode circuit is advantageously designed in such a way that it has two oppositely series-connected Zener diodes as equivalent circuit. It is particularly well suited to limiting high-frequency voltages and/or for limiting voltage pulses both of negative and of positive polarity. This diode circuit is, for example, a bidirectional diode arrangement marketed by the SGS Thomson company under the tradename of Transil™ diode.
The bidirectional trigger is advantageously dimensioned such that it has a breakdown voltage of at least 600 V and a clamping voltage of at least 800 V, without incurring damage.
REFERENCES:
patent: 4890041 (1989-12-01), Nuckolls et al.
patent: 9853647 (1998-11-01), None
Hirschmann Guenther
Rupp Arnulf
Bessone Carlo S.
Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen MBH
Vu David
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