Patent ID: 6504315
Filing Date: 2003-01-07
Classification: H05B,Y02B

Abstract:
In a ballast using a lamp system comprising a power supply for supplying power; a current controller for providing a controlled current, the current controller including a switch to control the magnitude of the power, the switch having an on/off state; a lamp section having at least one lamp for emitting light using the controlled current from the current controller, and a ballast comprising:an undervoltage protector for preventing a malfunction of the entire system, and generating an initial operating signal of the entire system upon receiving a voltage of less than a voltage capable of operating the entire system; a soft starter for gradually increasing a soft start voltage to a predetermine level to proceed with a start-up of the lamp upon receiving an initial operating signal from the undervoltage protector; a dimming controller for gradually increasing a voltage for dimming control even when an externally input dimming signal is changed in order to regulate the light intensity; a feedback section for forming a feedback voltage based on the magnitude of the current flowing through the lamp, comparing the feedback voltage with a reference voltage formed based on output signals from the soft starter and the dimming controller to perform the soft start and soft dimming operations of the lamp, and determining whether the current flowing through the lamp is an overcurrent, an undercurrent, or a normal current; a frequency controller for generating first and second frequencies for regulating the magnitude of the current input to the lamp based on a received signal from the feedback section, whereby the frequency controller generates the first frequency when the feedback voltage is greater than the reference voltage, the second frequency being generated when the feedback voltage is less than the reference voltage; and a switch driver coupled to the first and second frequencies to control the on/off state of the switch of the current controller.