Protective device for lighting system used in motor vehicle
AssigneeAlps Electric Co., Ltd.
InventorTakashi Murakami
Life of this patent
Estimating the term…
Abstract
A protective device for a lighting system to be used for a motor vehicle constituting a power supply and a light source energized with the power from the power supply. The power to be supplied to the light source is controlled by a driver. The driver is input with either a signal from a PWM pulse generator or a signal from a fixed duty pulse generator for the control of power to be supplied to the light source, and the changeover of these pulse generators is operated based on a detection signal from a voltage detector which monitors the voltage of the power supply.
Claims9
A protective device for a lighting system to be used in a motor vehicle comprising:
- a power supply;
- a light source energized by an amount of power supplied from said power supply;
- a driver for controlling the amount of power supplied to said light source, the driver being connected between said power supply and said light source;
- a pulse-width modulated (PWM) control circuit for generating a PWM signal;
- a fixed duty ratio pulse generator for supplying a fixed duty ratio oscillation signal;
- a voltage detector for detecting a voltage level of said power supply and for generating a detection signal in response to said detected voltage level, said voltage detector being connected to said power supply;
- a switching circuit for connecting one of said PWM signal from said PWM pulse generator and said fixed duty ratio oscillation signal from said fixed duty ratio pulse generator to said driver in response to said detection signal from said voltage detector.
A protective device for controlling an applied voltage level transmitted to a light source from a power supply in a motor vehicle, the power supply having a power supply voltage level, the protective device comprising:
- a driver connected between the power supply and the light source, the driver having a control terminal, the driver controlling the applied voltage level in response to a control signal received at the control terminal;
- a pulse-width modulated (PWM) control circuit for generating a PWM control signal, the PWM control circuit having a first output terminal;
- a fixed duty ratio pulse generator for generating a fixed duty ratio control signal, the fixed duty ratio pulse generator having a second output terminal;
- and
- a switching circuit for connecting the PWM control signal to the control terminal of the driver when the power supply voltage level is below a predetermined voltage level, and for connecting the fixed duty ratio control signal to the control terminal of the driver when the power supply voltage level is above the predetermined voltage level;
- wherein the applied voltage level is equal to or less than the predetermined voltage level.
Dependencies are inferred from the claim text.