Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Kazuhiko Harada

Jun Kumagai

Akira Nakajo

Nobuo Ukita

Naoki Komatu

Jun Kamagai

The lighting device includes a power conversion circuit and a control circuit. The power conversion circuit includes a high voltage side output terminal and a low voltage side output terminal to be connected to a light source, and a step-down chopper circuit. The control circuit performs a lighting operation of controlling the power conversion circuit to develop a DC output voltage between the high voltage side output terminal and the low voltage side output terminal. The control circuit starts a protective operation of limiting a current to be supplied to the light source when the output voltage is equal to or higher than a threshold value. The threshold value is in a range of 1.2 to 1.3 times a rated voltage of the light source.

Lighting device and illuminating fixture

A discharge lamp ballast and method of operation are provided for generating a DC component in an output voltage during a lamp starting operation having a predetermined duration. The ballast includes an inverter having four switches arranged in a full-bridge configuration, a resonant circuit having a resonant frequency, and a control circuit. The method includes a step of sweeping an inverter operating frequency within a predetermined frequency range including the resonant frequency, wherein a high voltage is generated for igniting the lamp. The method further includes periodically and alternately repeating a first state of turning on a first set of diagonally positioned switching elements and turning off a second set of diagonally positioned switching elements, and a second state of turning on only one of the second set of switching elements and turning off the remaining three switching elements, respectively.

Electronic ballast and method for providing a DC voltage component during lamp startup

Growing community of inventors

Hyogo, Japan

Kazuhiko Harada