Electronic device for the starting and a.c. voltage operation of a gas and/or vapor discharge lamp
First Claim
1. An electronic device for the starting and a.c. voltage operation of at least one electric discharge lamp provided with electrodes, the device comprising, at least two input terminals one of which is intended for connection to an electrode of the discharge lamp and the other of which is intended for connection to another lamp electrode, said two input terminals being interconnected by a circuit branch comprising a first controlled semiconductor switching element provided with a control circuit, the control circuit being operative such that, in the fully operating condition of the lamp with an a.c. voltage applied to said two terminals, the semiconductor switching element is made conductive for a period in every half cycle of the applied a.c. voltage, the control of the semiconductor switching element depending on the magnitude of the voltage between the said two input terminals, a second controlled semiconductor switching element having two switching states and connected to the first switching element so that only in a first switching state of the second switching element is the current through the first switching element blocked, means connecting a control electrode of the second switching element to a second control circuit arranged in parallel with a portion of the circuit branch which interconnects the said two input terminals and comprises at least the first switching element, and wherein the second control circuit includes a rectifier and has such a small time constant that, at least immediately after switch-on of the device, the second control circuit causes the second switching element to switch to its first switching state at the beginning of each alternate half cycle of the a.c. voltage.
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Accused Products
Abstract
An electronic device (20-61) for the starting and a.c. operation of a capacitively stabilized discharge lamp (7) includes a controlled semiconductor switching element (22) which, in the operating condition of the lamp, is briefly conductive in each half cycle of the AC supply. The control circuit of the semiconductor switching element (22) includes a second switching element (25) which, during the starting procedure of the lamp, ensures that the semiconductor switching element (22) is made conductive only every alternate half cycle thereby to improve the ignition of the lamp.
16 Citations
16 Claims
- 1. An electronic device for the starting and a.c. voltage operation of at least one electric discharge lamp provided with electrodes, the device comprising, at least two input terminals one of which is intended for connection to an electrode of the discharge lamp and the other of which is intended for connection to another lamp electrode, said two input terminals being interconnected by a circuit branch comprising a first controlled semiconductor switching element provided with a control circuit, the control circuit being operative such that, in the fully operating condition of the lamp with an a.c. voltage applied to said two terminals, the semiconductor switching element is made conductive for a period in every half cycle of the applied a.c. voltage, the control of the semiconductor switching element depending on the magnitude of the voltage between the said two input terminals, a second controlled semiconductor switching element having two switching states and connected to the first switching element so that only in a first switching state of the second switching element is the current through the first switching element blocked, means connecting a control electrode of the second switching element to a second control circuit arranged in parallel with a portion of the circuit branch which interconnects the said two input terminals and comprises at least the first switching element, and wherein the second control circuit includes a rectifier and has such a small time constant that, at least immediately after switch-on of the device, the second control circuit causes the second switching element to switch to its first switching state at the beginning of each alternate half cycle of the a.c. voltage.
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11. An electronic device for starting and operating at least one electric discharge lamp provided with electrodes and connected in series circuit with a ballast device including a capacitor across a pair of a.c. voltage supply terminals, said electronic device comprising,
first and second input terminals for connection to one lamp electrode and to another lamp electrode, respectively, a controlled semiconductor switching element having a control electrode, circuit means connecting said semiconductor switching element to said first and second input terminals, a first control circuit coupled to said switching element control electrode and to the a.c. voltage supply terminals for triggering the switching element into conduction in each half-cycle of the a.c. supply voltage in the operating condition of the discharge lamp, said control circuit including means responsive to the voltage between said first and second input terminals for controlling the trigger point of the semiconductor switching element depending on the magnitude of said voltage, a second controlled semiconductor switching element coupled to the first semiconductor switching element to inhibit conduction therein when said second semiconductor switching element is in a first switching state and to allow conduction of the first semiconductor switching element when the second semiconductor switching element is in a second switching state, and a second control circuit coupled to a control electrode of the second semiconductor switching element and connected in parallel with a portion of the circuit means that includes the first semiconductor switching element, said second control circuit including a rectifier connected in circuit so that during the start-up phase of the discharge lamp said second semiconductor switching element is triggered into said first switching state during alternate half-cycles of the a.c. supply voltage.
Specification