U.S. Philips Corporation

Paulus P Arts

Everaard M Aendekerk

Arnold Willem Buij

Wilhelmus H Langeslag

Marcel Beij

Pawel M Gradzki

Jerzy Janczak

Machiel A Hendrix

Etienne N Eberson

Jurgen M Willaert

In a circuit arrangement for operating a lamp comprising a power feedback and an antiboost switch disabling the power feedback for part of the time, the control of the antiboost switch is realized by means of a very simple and, hence, inexpensive control circuit.

Circuit arrangement

A circuit for supplying a discharge lamp, comprising a converter for generating a high-frequency current at a frequency f from a supply voltage and a circuit portion I for adjusting the power consumed by the discharge lamp through adjustment of the frequency. The circuit portion I is provided with a circuit portion II for low-frequency square-wave modulation of the frequency f and for the adjustment of the duty cycle of the square-wave modulation. As a result, the discharge lamp can be dimmed over a very wide range without striations or moding occurring and without undesirable shifts in the color point of the light.

Discharge lamp ballast circuit with duty cycle dimming control

A circuit for operating a discharge lamp from input terminals of a low frequency (f) supply voltage source with a rectifier coupled to the input terminals for rectifying the low-frequency supply voltage. A capacitor is coupled to the output of the rectifier. A DC-AC converter is coupled to the capacitor for generating a lamp current which comprises a DC component and a high-frequency AC component, the amplitude of the high-frequency AC component being modulated with a low frequency which is equal to twice the frequency f. An apparatus (V) adjusts the lamp power. The circuit parameters are chosen such that during operation the average amplitude of the high-frequency lamp current component is at least 500 times the amplitude of the low-frequency modulation of the high-frequency lamp current component with the power set for its maximum adjustable value. As a result, the discharge lamp can be dimmed over a wide range without striations occurring.

Ballast circuit for reducing striations in a discharge lamp

A circuit arrangement for high-frequency operation of a discharge lamp comprises a low-frequency rectifier for generating a DC voltage (buffer voltage) across a first capacitor (C1) from a low-frequency supply voltage. A DC/AC converter generates a high-frequency AC voltage from the buffer voltage. A load branch is coupled to the DC/AC converter and is provided with coupling terminals for coupling the discharge lamp to the load branch. A high-frequency rectifier (HR) converts the high-frequency voltage generated by the DC/AC converter into a DC voltage and comprises a series arrangement of first and second diodes (D5, D6) which have the same orientation. A control circuit (CR) controls the power consumed by the discharge lamp to a level which is dependent on a control signal (Sg). The high-frequency rectifier further comprises a switching device and a further control circuit (CR1). The switching device shunts at least one of the diodes of a feedback unit. The further control circuit controls the switching device dependent on the control signal.

Dimmable ballast with active power feedback control

The invention relates to a circuit arrangement for operating a discharge lamp with a high frequency current comprising a power feedback circuit and a electrode preheater. The circuit arrangement comprises an antiboost switch for disabling the power feedback circuit before the lamp has ignited and enabling the power feedback circuit after the lamp has ignited- In accordance with the invention the antiboost switch is also used to enable the electrode preheater before the lamp has ignited and to disable the electrode preheater after the lamp has ignited.

Discharge lamp device having a preheating electrode circuit

The invention relates to a circuit arrangement for operating a discharge lamp with a high frequency current comprising a power feedback circuit and an electrode preheater. The circuit arrangement comprises an antiboost switch for disabling the power feedback circuit before the lamp has ignited and enabling the power feedback circuit after the lamp has ignited. In accordance with the invention the antiboost switch is also used to enable the electrode preheater before the lamp has ignited and to disable the electrode preheater after the lamp has ignited.

Discharge lamp with heating electrode circuit

A circuit arrangement for the high-frequency operation of a discharge lamp comprises a first rectifying circuit (D1-D4) for generating a DC voltage across a first capacitor (C1) from a low-frequency supply voltage. A DC/AC converter (IV) for generating a high-frequency AC voltage at a frequency f from the DC voltage is coupled to a load branch (B) provided with coupling means (T3, T4) for coupling the discharge lamp (Li) to the load branch. The load branch connects a junction point N1 of the DC/AC converter to a junction point N2 between the first rectifying circuit and the first capacitor. A second rectifying circuit for converting a high-frequency voltage generated by the DC/AC converter into a DC voltage is coupled to the first capacitor and to a junction point N3 in the load branch. A control circuit controls the power consumed by the discharge lamp through variation of the frequency f. The coupling means are connected between the junction point N2 and the junction point N3 in the load branch.

Growing community of inventors

Eindhoven, Netherlands

Paulus P Arts