Samsung Electronics Co., Ltd.

Fairchild Korea Semiconductor Ltd.

Fairfield Korea Semiconductor Ltd.

Nak-Choon Choi

Maeng-Ho Seo

Dae-Bong Kim

Kyung-Hee Jang

Maeong-Ho Seo

An electronic ballast for use in illuminating a lamp includes a voltage reference generator that uses a plurality of current amplifiers and resistors having substantially identical resistance characteristics to remain stable in response to temperature variations and despite resistance process dispersion. The reference voltage generator further includes an ON/OFF controller and a dimming function that may be controlled via a single input terminal. Additionally, the dimming function uses a capacitor to prevent abrupt changes in an input signal from causing abrupt changes in a feedback signal that controls an output frequency of the ballast.

Electronic ballast having a stable reference voltage and a multifunction input for soft dimming and ON/OFF control

An electronic ballast for use in illuminating a lamp includes a lamp driving circuit having a pulse-width modulated signal generator, a timing capacitor coupled to the lamp driving circuit, and a power controller. The power controller uses a current sense resistor to detect a current flowing through the lamp and an operational amplifier circuit to compare a signal associated with the detected current to a reference voltage associated with a desired lamp current. Based on the comparison, the power controller provides a correction current to the timing capacitor to control a duty cycle of an output of the pulse-width modulated signal generator.

Electronic ballast system

Disclosed is an electric ballast system. The system comprises a voltage source for supplying power to the electric ballast system; a lamp driving circuit having a first terminal, a second terminal, and a third terminal, the power of the voltage source being supplied through the first terminal to begin the driving of the electric ballast system, and the lamp driving circuit outputting PWM waves through the second and third terminals; a half bridge converter, a first end of which is connected to the second terminal of the lamp driving circuit and a second end of which is connected to the third terminal of the lamp driving circuit, the half bridge converter receiving input through the second and third terminals of the lamp driving circuit, and the half bridge converter performing output of a current which changes flow directions according to the PWM waves output by the lamp driving circuit; a lamp portion, a first end of which is connected to an output end of the half bridge converter, the lamp operating according to the current output by the half bridge converter; and a lamp protector connected between a second end of the lamp and the first terminal of the lamp driving circuit, the lamp protector discontinuing the operation of the lamp driving circuit if there is no bulb installed in the lamp.

Electric ballast system

A Power Factor Correction (PFC) circuit according to the present invention includes a boost converter which outputs a predetermined voltage according to control of a switch. The switch is coupled to a resistor and a capacitor which, by forming a current detector, detect the current flowing through an inductor of the boost converter. The output voltage of the boost converter is divided by resistors, and the voltage difference between the divided voltage and a reference voltage is amplified by an error amplifier. The output voltage of the error amplifier and a reverse sawtooth waveform provided from an oscillator are input in a multiplier so as to be multiplied by a gain, and output voltages of the multiplier and of the current detector are provided to a switching driver. The switching driver turns off the switch when the output voltages of the current detector and of the multiplier are equal, and turns on the switch when the state of the reference clock signal is changed.

Power factor correction circuit using reverse sawtooth waves

Disclosed is a Power Factor Correction (PFC) controller which comprises a boost converter, an error amplification unit, a calculator, and a switching driver. The error amplification unit reduces the error voltage of the output voltage of the boost converter to a specific reference voltage. The calculator receives first and second input voltages proportional to the input power of the converter and the output voltage of the error amplification unit, and outputs the voltage proportional to the first input voltage and the output voltage of the error amplification unit and inversely proportional to the second input voltage. The switching driver controls the switch to OFF when the voltage which detects the current flowing to switch of the boost converter becomes equal to the output voltage of the calculator, and controls the switch to ON when the zero current of the coil of the boost converter is detected.

Power factor correction (PFC) controller

A sequential feedback control system for an electronic ballast provides feedback control during soft start and dimming operations. The system includes a feedback control portion that generates a feedback signal responsive to the power consumption of the ballast and receives a control signal for controlling the power consumption of the ballast. A dimming controller generates a dimming signal responsive to a time signal, and a soft start controller generates a soft start signal responsive to the time signal. An adder generates the control signal by adding the feedback signal and the dimming signal. The dimming controller includes a first resistor for setting the steady state power level during dimming operations and a second resistor for setting the rate of change of the power level.

Sequential feedback control system for an electronic ballast

A power factor correction circuit for a boost converter includes a current feedforward loop that senses the input voltage by detecting variations in the rate of change of current in an inductor, thereby eliminating the need for a voltage feedforward loop. A current sense circuit generates a current signal responsive to the input current flowing through the inductor when a switching transistor is turned on. A comparator compares the current signal to a sawtooth signal, thereby generating a control signal for turning the transistor off. The output of the converter is controlled by a voltage feedback loop which includes an error amplifier that generates an error signal responsive to the output voltage. The error signal is then multiplied by the current signal before the current signal is compared to the sawtooth signal.

Power factor correction circuit having an error signal multiplied by a

The present invention relates to a feedback control system and method for controlling an electronic ballast for driving a lamp where the lamp requires preheating of a cathode of the lamp in order for the electronic ballast to successfully discharge into the lamp and initiate arcing operation in the lamp. The system detects the power consumption level of the lamp and, when the power consumption level indicates that the lamp is not arcing, performs a restart of the lamp wherein the restart function includes preheating the cathode with a preheating current. The present invention reduces production cost and increases safety by detecting operation in the lamp without using external elements.

Feedback control system of an electronic ballast which detects arcing of

A power factor correction circuit for a boost-type voltage converter determines the input voltage by sensing the rate at which the current through an inductor changes when a switching transistor is turned on. The circuit includes a current sense circuit which generates a control signal in response to the current flowing in the inductor. The control signal is compared with a sawtooth signal to control the input current waveform. An output detecting circuit generates a comparison reference signal for regulating the output voltage of the converter. The comparison reference signal is summed with the control signal to provide a comparison signal. A comparison circuit compares the comparison signal with the sawtooth signal and generates a pulse width modulated signal for controlling the switch. A compensation signal generator generates a compensated comparison signal in response to a ripple component in the output signal of the converter. The compensated comparison signal is summed with the sawtooth signal to compensate for distortion in the input current, thereby increasing the power factor. An amplifier in the sense circuit allows a low value sense resistor to be used.

Power factor correction circuit having indirect input voltage sensing

A power factor correction circuit in which an inductor current is detected separately as a charging current indication signal and a discharging current indication signal by using a current sense resistor and a current sense circuit. A scaled-down output DC voltage is compared with a predetermined reference DC voltage by using an error amplifier which serves to produce an output voltage error signal. The output voltage error signal is then multiplied with a divided-down rectified input line voltage through the use of the multiplier to generate a sinusoidal reference signal. The sinusoidal reference signal is used by peak and valley comparators which also receive the charging and the discharging current indication signals. The outputs from the peak and the valley comparators are used to control a FET transistor which controls the input line current. As a result, the power factor correction circuit is capable of effectively eliminating a dead time and thereby achieving a near unity power factor.

Growing community of inventors

Kyungki-do, South Korea

Nak-Choon Choi