Patent ID: 6194843
Filing Date: 2001-02-27
Classification: H05B,Y02B,Y10S

Abstract:
A ballast circuit for energizing a HID lamp, comprising:an inverter circuit having two switching elements for providing an AC drive signal to the lamp;a resonant inductive element coupled between said switching elements and the lamp; anda hot restart circuit coupled to the lamp when the lamp is connected in circuit for applying a voltage to the lamp that is sufficient to achieve hot restart of the lamp, the hot restart circuit including:a first inductor coupled to the lamp;a second inductor inductively coupled to the first inductor, said second inductor having first and second ends, said first end being directly connected to the lamp and said second end being connected to an end of the first inductor at a junction;a first capacitor coupled to the second inductor at said junction; anda first switching element coupled to the first capacitor, said first switching element, said first capacitor, and said second inductor selectively forming a circuit loop such that a transition of the first switching element to a first state generates a voltage pulse on the second inductor which induces a corresponding voltage pulse on the first inductor for hot restart of the lamp.