Panasonic Corporation

Tetsuya Hamana

Masafumi Yamamoto

Hiroyuki Asano

Takashi Kambara

A lighting device includes: a power conversion unit which converts a direct current (DC) power into a power required by a load; an output current detection unit which detects an output current of the power conversion unit; and a source voltage detection unit which detects a source voltage. Further, the lighting device includes an operation unit which calculates an output current command value so as not to exceed an upper limit of the output current command value set according to a resistance value of an externally connected resistor; and a control unit which controls the power conversion unit such that the output current thereof the power conversion unit becomes the output current command value.

Lighting device, headlamp lighting device, and headlamp unit and vehicle having same

A control means has an adjustment function in a microprocessor to adjust variations in an output to a discharge lamp due to variations in components by correcting a duty ratio of a PWM signal for varying an operating frequency of an inverter circuit so that a detected value of a second detection circuit falls within a target range. The microprocessor switches paths to transmit the PWM signal between a path passing through a feedback circuit and a path passing through a voltage follower circuit by switches a switch circuit to supply the signal through the path passing through the voltage follower circuit in adjusting output variations in the preheating mode and the starting mode.

Electronic ballast with multimode lamp power control

An electronic ballast A includes an inverter circuit for converting a DC voltage into a high-frequency voltage, a resonant circuit which is connected between outputs of the inverter circuit and lights a discharge lamp at a high frequency by a resonant action, a dimming circuit for changing an output voltage to the discharge lamp by changing an operating frequency of the inverter circuit, a DC component detecting circuit for detecting a DC voltage component of the discharge lamp and a control operating circuit which detects an output signal of the DC component detecting circuit for every predetermined period to reduce or stop an output to the discharge lamp in the case where the output signal exceeds a predetermined reference value and to prohibit the protection operation when periodic change amount in the output signal reaches a predetermined value or higher.

Electronic ballast with lamp end of life detection and protection circuits

A electronic ballast includes an inverter circuit for converting a DC voltage into a high-frequency voltage, a resonant circuit connected between outputs of the inverter circuit so as to light a discharge lamp by a resonant action, a control circuit for controlling the inverter circuit, a dimming circuit for continuously changing an output voltage to the discharge lamp by changing an operation frequency in the inverter circuit, a DC component detection circuit and a voltage comparator for detecting whether or not the discharge lamp is at the end of the life at predetermined intervals and outputting an end of life detection signal upon detection of the end of the life state, and a frequency control circuit and a driving circuit for reducing or stopping an output to the discharge lamp by controlling switching elements in response to a life end detection signal inputted from the voltage comparator.

Growing community of inventors

Nara, Japan

Tetsuya Hamana