Patent application number | Description | Published |
20090009256 | VARIABLE-FREQUENCY OSCILLATOR - There is provided a frequency-variable oscillator that varies, even when a frequency of an input signal is varied, a frequency of an oscillation signal according to the varied frequency of the input signal. A frequency-variable oscillator according to an aspect of the invention includes: a voltage-to-current converter circuit converting a voltage level of an input signal into a current level within a predetermined range; and an oscillator circuit varying a frequency according to the current level from the voltage-to-current converter circuit and oscillating the varied frequency. | 01-08-2009 |
20090058467 | PHASE DETECTION APPARATUS - There is provided a phase detection apparatus that can accurately detect a phase difference between an input signal and a reference signal even when the input signal and the reference signal have different duty cycles. A phase detection apparatus according to an aspect of the invention may include: a pulse generation unit generating a first pulse signal on an edge of an input pulse signal, and a second pulse signal based on an edge of a reference pulse signal having a predetermined phase; and a detection unit detecting a phase difference between the first pulse signal and the second pulse signal from the pulse generation unit. | 03-05-2009 |
20090058793 | BACKLIGHT UNIT FOR SYNCHRONIZATION WITH AN IMAGE SIGNAL FOR LIQUID CRYSTAL DISPLAY - A backlight unit for synchronization with an image signal for a liquid crystal display (LCD), which can synchronize frequencies of a lamp driving signal and a lamp brightness signal with frequencies of a horizontal synchronization signal and a vertical synchronization signal, which are image signals used in an LCD panel. The backlight unit includes a synchronization part generating a first synchronized signal synchronized with a horizontal synchronization signal having a preset frequency, and a second synchronized signal synchronized with a vertical synchronization signal having a frequency different from the frequency of the horizontal synchronization signal, and a signal generation part generating a lamp driving signal for driving a lamp according to the first synchronized signal and a lamp brightness signal for controlling brightness of the lamp according to the second synchronized signal. | 03-05-2009 |
20090128055 | APPARATUS FOR DRIVING LIGHT EMITTING ELEMENT - Provided is an apparatus for driving a light emitting element. The apparatus includes a power unit, a light emitting element array, a constant-current circuit unit, and a voltage limiting circuit unit. The power unit supplies driving power. The light emitting element array includes a plurality of light emitting elements connected in series between an anode terminal connected to the power unit and a cathode terminal. The constant-current circuit unit maintains a constant current flowing through the light emitting element array according to a first tuning voltage. The voltage limiting circuit unit is connected between the cathode terminal of the light emitting element array and the constant-current circuit unit, and divides a total voltage applied between the cathode terminal of the light emitting element array and a ground according to a second tuning voltage to limit a voltage applied to the constant-current circuit unit below a predetermined voltage. | 05-21-2009 |
20100102750 | LIGHT EMITTING DIODE HAVING PROTECTION FUNCTION - The present invention relates to a light emitting diode driver having a protection function that activates hiccup mode for a predetermined period of time when a light emitting diode performs an abnormal operation to thereby protect the light emitting diode. A light emitting diode driver having a protection function according to an aspect of the invention may include: a light emitting unit emitting light; a reference signal generating unit generating a reference signal having pulses with a predetermined period when the light emitting unit performs an abnormal operation; a control unit controlling operating time in hiccup mode according to the reference signal from the reference signal generating unit, the hiccup mode where output is switched on and off at a predetermined period; and a driving unit driving the light emitting unit in the hiccup mode for the operating time determined by the control unit. | 04-29-2010 |
20100109547 | LCD BACKLIGHT INVERTER - Disclosed is a liquid crystal display (LCD) backlight inverter. The LCD backlight inverter includes a lamp open detection unit outputting a first open detection voltage for a preset time period when it is determined that a predetermined lamp is open, based on a current voltage corresponding to the current of the predetermined lamp of a plurality of lamps, a first open determination unit outputting an open detection signal when the first open detection voltage is input, a second open determination unit outputting a protection signal when it is determined that all of the plurality of lamps are open based on detection voltages of the plurality of lamps, a temporary protection determination unit outputting a frequency change signal when both the open detection signal and the protection signal are input, and an operating frequency control unit changing an operating frequency to a preset protective frequency according to the frequency change. | 05-06-2010 |
20100134450 | DRIVER FOR DISPLAY - A driver for display provides a driving signal having a frequency synchronized with that of an image signal when the image signal is normal and provides a driving signal having a predetermined frequency when the image signal is abnormal, thereby performing a stable operation. The driver includes a frequency detection unit detecting a frequency difference between a frequency of an inputted image signal and a frequency of a frequency-divided driving signal, a driving signal generation unit generating the driving signal having a frequency synchronized with the frequency of the image signal according to a detection result of the frequency detection unit, and a control unit stopping a frequency detection operation of the frequency detection unit when the detection result of the frequency detection unit shows an abnormal operation. | 06-03-2010 |
20100141300 | INVERTER DRIVER INTEGRATED CIRCUIT - An inverter driver integrated circuit (IC) includes a control signal generator generating a first control signal and a second control signal by use of a pulse width modulation oscillator signal, a comparator comparing a half-wave rectified signal of a lamp feedback signal fed back from a lamp with a preset reference signal to output a lamp state signal, a first sensor receiving the lamp state signal and the second control signal to output a first sensing signal, and a second sensor receiving the first sensing signal and the first control signal to output a second sensing signal. | 06-10-2010 |
20110062884 | REFERENCE SIGNAL GENERATOR AND PWM CONTROL CIRCUIT FOR LCD BACKLIGHT - There are provided a reference signal generator and a PWM control circuit for LCD backlight. The reference signal generator and the PWM control circuit for LCD backlight may be configured to respectively include: a current control unit that controls generation of a variable current sequentially changing; a current generating unit that generates a variable current changing sequentially; and a reference signal generating unit that controls charging until a charged voltage charged by the variable current generated by the current generating unit reaches a first reference voltage level, starts discharging when the charged voltage reaches the first reference voltage level, controls discharging until the charged voltage reaches a second reference voltage level, and generates a triangular wave reference signal that has a frequency buffering interval in which a frequency sequentially changes when the initial driving completion signal or the protection signal is input. | 03-17-2011 |
20120086515 | RELAXATION OSCILLATOR - There is provided relaxation oscillator. The relaxation oscillator includes: a ramp wave generator generating ramp waves by a complementary operation between a first capacitor module charged and discharged according to a first switching signal and a second capacitor module charged and discharged according to a second switching signal; a negative feedback circuit unit generating a compensation voltage for compensating errors with reference voltage by being fedback with the ramp waves; and a switching signal generator generating the first switching signal controlling the charging and discharging of the first capacitor module and the second switching signal controlling the charging and discharging of the second capacitor module from the compensation voltage and the ramp waves. As a result, the present invention can generate ramp waves having a stable frequency while preventing a frequency from being changed due to a delay or an offset of the comparator. | 04-12-2012 |
20120229042 | INVERTER FOR CONTROLLING BACKLIGHT USING VARIABLE FREQUENCY OSCILLATOR - There is provided an inverter for controlling a backlight using a variable frequency oscillator, the inverter including: a variable frequency oscillator generating a reference waveform having a variable frequency through voltage charged in a first capacitor and voltage discharged therefrom by a current; and a main switching signal generator generating a switching signal for driving a plurality of lamps based on a first error voltage between output voltages corresponding to currents flowing in the lamps and a first reference voltage and the reference waveform, whereby damage of circuit elements such as the lamps, or the like, may be prevented and the brightness of the lamps may be constantly maintained. | 09-13-2012 |
20140176089 | PHASE SHIFT CIRCUIT AND POWER FACTOR CORRECTION CIRCUIT INCLUDING THE SAME - There are provided a phase shift circuit and a power factor correction circuit including the same. The phase shift circuit includes a ramp generation unit charging or discharging a capacitor connected to a switch device to generate a ramp signal, a reference signal generation unit generating a predetermined reference signal from the ramp signal, and a comparison unit comparing the ramp signal with the reference signal to generate a clock signal, wherein at least one of the reference signal generation unit and the comparison unit changes a negative or positive value of offset components included in the reference signal or the ramp signal within every operating period of the switch device. | 06-26-2014 |
20140177295 | PHASE SHIFT CIRCUIT AND POWER FACTOR CORRECTION CIRCUIT INCLUDING THE SAME - There are provided a phase shift circuit and a power factor correction circuit including the same. The phase shift circuit includes a switching circuit unit charging power in or discharging power from a capacitor through a plurality of switching devices and comparing a voltage of the capacitor with a predetermined reference voltage, and a clock generating unit generating a reference clock signal based on an output of the switching circuit unit, wherein the switching circuit unit turns the plurality of switching devices on or off, based on currents from inductors respectively included in a main circuit and a sub-circuit of a power factor correction circuit to determine a polarity of the voltage of the capacitor. | 06-26-2014 |
20140185339 | POWER FACTOR CORRECTION CIRCUIT - There is provided a power factor correction circuit including: a power conversion circuit unit controlling an inductor current according to a switching signal applied to a main switch to convert an external input voltage into an output voltage having a predetermined range; an imbalance detection circuit outputting an imbalance state signal when the external input voltage is in an unbalanced state by using the inductor current; and a soft start circuit unit performing soft starting by adjusting the switching signal when the imbalance state signal is output by the imbalance detection circuit unit. | 07-03-2014 |