Abstract:
A gas discharge lamp ballast with an indicator of operability of the ballast is disclosed. The ballast circuit comprises circuitry for providing a d.c. bus voltage on a bus conductor with respect to a ground, and a resonant load circuit. The resonant load circuit includes lamp terminals for connecting to a removable gas discharge lamp, a resonant inductor, and a resonant capacitor. The resonant inductor and resonant capacitor are selected to set a magnitude, and resonant frequency, of a bidirectional current in the lamp. Further included is a converter circuitry, including first and second serially connected switches coupled between the bus conductor and the ground, and providing to the resonant load circuit, at a node coupled between the first and second switches, a voltage that alternates between first and second voltage levels. Circuitry for generating first and second switch control signals for alternately switching into conduction the first and second switches, including circuitry responsive to a feedback signal representing a current in the resonant load circuit, are further included. The ballast circuit, moreover, includes overload detection circuitry for detecting if voltage applied to the lamp terminals exceeds an overload level; and circuitry for indicating, in response to such an overload condition being detected by the overload detection circuitry, probable operability of the ballast circuit.
Abstract:
Disclosed is an electrodeless, low pressure gas discharge lamp (10). The lamp (10) includes a vitreous envelope (12) containing a metal vapour and an inert gas. The envelope (12) is shaped with an external chamber (14) for receiving an electrical excitation circuit. The excitation circuit is effective for exciting the metal vapour to emit light with electromagnetic fields that are passed through the vitreous envelope (12) from outside, to inside, the envelope (12). A circuit supplies electrical power from power mains to the excitation circuit. A transparent, electrically conductive coating (26) is disposed on the inner surface of the vitreous envelope (12) for suppressing electromagnetic interference on the power mains. An electrically conductive coating (30) is disposed on the outer surface of the vitreous envelope (12); it is capacitively coupled to the inner conductive coating (26), via a wall of the vitreous envelope (12), and is maintained at a suitable potential for suppressing electromagnetic interference on the power mains. The outer conductive coating (30) comprises a matrix (40) of a contiguous, inorganic, glass layer bonded to an exterior surface of the vitreous envelope (12), and conductive particles (42) embedded in the matrix (40) in a sufficiently dense manner to form a conductive coating.
Abstract:
An electrodeless fluorescent lamp includes a coil assembly which comprises a hollow ferrite core (30), and a coil (31). The core is retained on a base (32) by a coil former (34) surrounding the core. The core (30) is retained in the former (34) by a circlip (33) or by projections. The coil (31) is wound on the former. Pins (36) to which the coil is soldered connect the coil to an energising circuit.
Abstract:
A gas discharge lamp ballast with an indicator of operability of the ballast is disclosed. The ballast circuit comprises circuitry for providing a d.c. bus voltage on a bus conductor with respect to a ground, and a resonant load circuit. The resonant load circuit includes lamp terminals for connecting to a removable gas discharge lamp, a resonant inductor, and a resonant capacitor. The resonant inductor and resonant capacitor are selected to set a magnitude, and resonant frequency, of a bidirectional current in the lamp. Further included is a converter circuitry, including first and second serially connected switches coupled between the bus conductor and the ground, and providing to the resonant load circuit, at a node coupled between the first and second switches, a voltage that alternates between first and second voltage levels. Circuitry for generating first and second switch control signals for alternately switching into conduction the first and second switches, including circuitry responsive to a feedback signal representing a current in the resonant load circuit, are further included. The ballast circuit, moreover, includes overload detection circuitry for detecting if voltage applied to the lamp terminals exceeds an overload level; and circuitry for indicating, in response to such an overload condition being detected by the overload detection circuitry, probable operability of the ballast circuit.
Abstract:
A gas discharge lamp ballast (10) circuit comprises circuitry for providing a d.c. bus voltage (V B ) on a bus conductor (16) with respect to a ground, and a resonant load circuit (18). The resonant load circuit includes lamp terminals for connecting to a removable gas discharge lamp, a resonant inductor (L R ), and a resonant capacitor (C R ). The resonant inductor and resonant capacitor are selected to set a magnitude, and resonant frequency, of a bidirectional current in the lamp. Further included is a converter circuitry, including first (S 1 )and second (S 2 ) serially connected switches coupled between the bus conductor and the ground, and providing to the resonant load circuit, at a node (12) coupled between the first and second switches, a voltage that alternates between first and second voltage levels. Circuitry (24,26) for generating first and second switch control signals for alternately switching into conduction the first and second switches, including circuitry responsive to a feedback signal representing a current in the resonant load circuit, are further included. The ballast circuit includes, a starter circuit arrangement (48) coupled to the converter circuit arrangement to generate a pulse to start conduction of one of said first and second switches. The starter pulse circuit arrangement includes an electric switch coupled between the d.c. bus conductor and ground to switch into a conducting state whenever the bus conductor is initially brought to a rated bus voltage. The electrical switch is a latch-type switch that remains conducting until such time as the bus voltage falls substantially towards the potential of ground.
Abstract:
An electrodeless fluorescent lamp includes a coil assembly which comprises a hollow ferrite core (30), and a coil (31). The core is retained on a base (32) by a coil former (34) surrounding the core. The core (30) is retained in the former (34) by a circlip (33) or by projections. The coil (31) is wound on the former. Pins (36) to which the coil is soldered connect the coil to an energising circuit.
Abstract:
Disclosed is an electrodeless, low pressure gas discharge lamp (10). The lamp (10) includes a vitreous envelope (12) containing a metal vapour and an inert gas. The envelope (12) is shaped with an external chamber (14) for receiving an electrical excitation circuit. The excitation circuit is effective for exciting the metal vapour to emit light with electromagnetic fields that are passed through the vitreous envelope (12) from outside, to inside, the envelope (12). A circuit supplies electrical power from power mains to the excitation circuit. A transparent, electrically conductive coating (26) is disposed on the inner surface of the vitreous envelope (12) for suppressing electromagnetic interference on the power mains. An electrically conductive coating (30) is disposed on the outer surface of the vitreous envelope (12); it is capacitively coupled to the inner conductive coating (26), via a wall of the vitreous envelope (12), and is maintained at a suitable potential for suppressing electromagnetic interference on the power mains. The outer conductive coating (30) comprises a matrix (40) of a contiguous, inorganic, glass layer bonded to an exterior surface of the vitreous envelope (12), and conductive particles (42) embedded in the matrix (40) in a sufficiently dense manner to form a conductive coating.