Discharge lamp operating circuit with frequency control of dimming and lamp electrode heating
First Claim
1. A circuit arrangement for high-frequency operation of a discharge lamp, comprising:
- input terminals for connection to a supply voltage source,a load branch including terminals for connecting to the discharge lamp and an electrode heating transformer provided with a primary winding and secondary windings, each secondary winding being shunted by a branch comprising an electrode of the discharge lamp,at least one switching element for generating a high-frequency current through the load branch from a supply voltage delivered by the supply voltage source,a control circuit for generating and supplying to said switching element a control signal for rendering the switching element conducting and non-conducting at a high frequency,a dimmer circuit coupled to the control circuit for adjusting the frequency of the control signal, and wherein each branch shunting a secondary winding of the transformer comprises inductive means and capacitive means and has a resonance frequency which is different from the resonance frequency of the load branch.
1 Assignment
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Accused Products
Abstract
A circuit for high-frequency operation of a discharge lamp. The circuit includes a load branch provided with terminals for connection to the discharge lamp and with an electrode heating transformer having a primary winding and secondary windings. Each secondary winding is shunted by a branch comprising an electrode of the discharge lamp. At least one switching element generates a high-frequency current through the load branch from a supply voltage. A control circuit generates a control signal for rendering the switching element conducting and non-conducting at a high frequency. A dimmer circuit is coupled to the control circuit for adjusting the frequency of the control signal. Each branch shunting a secondary winding of the transformer also includes an inductive element and a capacitive element and has a resonance frequency which is different from the resonance frequency of the load branch. Thus, a discharge lamp operated by this circuit can be dimmed over a wide range and provides a comparatively long electrode life and with very little blackening at the ends of the discharge vessel.
45 Citations
11 Claims
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1. A circuit arrangement for high-frequency operation of a discharge lamp, comprising:
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input terminals for connection to a supply voltage source, a load branch including terminals for connecting to the discharge lamp and an electrode heating transformer provided with a primary winding and secondary windings, each secondary winding being shunted by a branch comprising an electrode of the discharge lamp, at least one switching element for generating a high-frequency current through the load branch from a supply voltage delivered by the supply voltage source, a control circuit for generating and supplying to said switching element a control signal for rendering the switching element conducting and non-conducting at a high frequency, a dimmer circuit coupled to the control circuit for adjusting the frequency of the control signal, and wherein each branch shunting a secondary winding of the transformer comprises inductive means and capacitive means and has a resonance frequency which is different from the resonance frequency of the load branch. - View Dependent Claims (2, 3, 4)
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5. A discharge lamp operating apparatus having a dimming function comprising:
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input terminals for connection to a source of supply voltage, a load circuit comprising terminals for connection to respective electrodes of the discharge lamp and an electrode heating transformer including a primary winding and first and second secondary heater windings for coupling to first and second electrodes of the discharge lamp, respectively, said load circuit having a resonant frequency, at least one controlled switching element coupled to said input terminals and arranged to supply an alternating current to said load circuit, a control circuit having an output coupled to a control electrode of the controlled switching element and arranged to generate a control signal for switching the controlled switching element on and off so as to derive said alternating current for the load circuit, a dimmer circuit coupled to a control input of the control circuit for adjusting the frequency of the control signal, and inductive means and capacitive means coupled to said first and second secondary winding so as to form first and second resonant circuits each having a resonant frequency that is different than the resonant frequency of the load circuit. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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Specification