Samsung Electro-mechanics Co., Ltd.

Sang Cheol Shin

Byoung Own Min

Jung Chul Gong

Chang Woo Ha

Yu Jin Jang

Seung Kon Kong

Jeong In Cheon

Bon Ahm Goo

Deuk Hee Park

Bo Hyun Hwang

Kyoung Soo Kwon

Yun Jin Jang

An apparatus for driving a light emitting device according to an aspect of the invention may include: a DC/DC converter unit generating driving power on the basis of an input voltage and supplying the generated driving power to an anode of a light emitting unit including a plurality of light emitting devices; a current source controlling to keep current flowing through the light emitting unit constant; a feedback circuit unit detecting voltage at a cathode of the light emitting unit; and a feedback coupling circuit unit coupling the output of the feedback circuit unit and the input of the DC/DC converter unit to supply the input voltage of the DC/DC converter unit according to the voltage detected by the feedback circuit unit and an output voltage of the DC/DC converter unit.

Apparatus for driving light emitting device

An apparatus for driving multi-light emitting devices that drives a multi-channel light emitting unit having a plurality of light emitting channels connected in parallel with each other, each of which has a plurality of light emitting devices connected in series with each other according to an aspect of the invention may include: a DC/DC converter generating a driving voltage; a current control unit having a plurality of current sources connected between cathodes of the plurality of light emitting channels and a ground; a minimum voltage selection unit detecting a minimum detection voltage among the plurality of detected voltages at the cathodes of the plurality of light emitting channels; a first error detection unit detecting an error voltage determined by the difference between the minimum detection voltage and a predetermined first reference voltage; and a feedback coupling unit supplying the input voltage according to the error voltage and the driving voltage.

Apparatus for driving multi-light emitting devices

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.

LCD backlight inverter

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.

Apparatus for driving light emitting element

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. The frequency-variable oscillator includes: a voltage-to-current converter circuit for converting a voltage level of an input signal into a current level within a predetermined range; and an oscillator circuit for varying a frequency according to the current level from the voltage-to-current converter circuit and oscillating the varied frequency.

Variable-frequency oscillator

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.

Inverter driver integrated circuit

An inverter driving circuit for an LCD is switched on/off more stably to improve heating radiation characteristics and drive efficiency. In the driving circuit, a controller supplies a first driving signal. A level shifter provides a second driving signal. A first delay circuit delays a rising section of the first driving signal to provide the first driving signal. A second delay circuit delays a falling section of the second driving signal to provide the second driving signal. Also, a power switching circuit is provided. The inverter driving circuit for the LCD, when a switching device thereof is turned off, has less current flowing in the switching device, thereby generating less heat. In addition, the inverter driving circuit prevents heat generation caused by current flowing reversely in the switching device, thereby enhancing drive efficiency.

Inverter driving circuit for LCD backlight

In a time control circuit, a capacitor is connected between a connecting pin and a ground. A first current source supplies a first current to the connecting pin. A first comparator element has a non-inverse terminal connected to a voltage of the capacitor and a pre-set first reference voltage, and controls the initial startup time. A second comparator element has an inverse terminal connected to the voltage of the capacitor and a pre-set second reference voltage, and controls the soft start time. Further, a current bypass controller includes a current bypass path between the connecting pin and the ground, which connects the current bypass path after the soft start time and blocks it at an input of a protective signal. Additionally, a third comparator element has an inverse terminal connected to the voltage of the capacitor and a pre-set third reference voltage, and controls the shutdown time.

Time control circuit for backlight inverter

Disclosed herein is a drive device of a color light emitting diode (LED) backlight, which is capable of precisely adjusting the forward voltages of color LED arrays for each channel. The drive device for driving the color light emitting diode (LED) backlight which includes a plurality of color LED arrays includes an I/O interface for inputting/outputting a signal, a control unit for controlling a driving voltage and driving current according to a brightness control signal output from the I/O interface, a DC/DC converter for converting an operation voltage into the driving voltage according to the driving voltage control of the control unit, a voltage regulator for regulating the driving voltage output from the DC/DC converter to a reference voltage without ripple, a multi-channel driving unit for converting the reference voltage output from the voltage regulator into forward voltages of the plurality of color LED arrays according to a plurality of control signals, and a current source for adjusting the amount of the driving current flowing in the color LED backlight according to the driving current control of the control unit.

Drive device of color LED backlight

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.

Phase detection apparatus

An LCD backlight inverter includes a soft starter for generating a soft-start reference voltage gradually increasing as the driving power begins to be supplied. The LCD backlight inverter also includes a first error detector for receiving a first feedback voltage indicating the magnitude of driving current of the lamp and for comparing a smaller value out of a predetermined first reference voltage and the soft-start reference voltage with the first feedback voltage to generate a first error signal corresponding to the difference between the smaller value and the soft-start reference voltage. The LCD backlight inverter further includes a pulse width modulation comparator for comparing the first error signal and a triangle wave oscillation signal to output the pulse width modulation control signal with a predetermined duty ratio. The LCD backlight inverter prevents application of over-current and over-voltage to the LCD backlight to prolong the lifetime of the backlight.

Liquid crystal display backlight inverter

In a driving circuit for an LCD backlight, a fundamental wave generator generates a triangle wave signal and a square wave signal in accordance with time constant of a time constant circuit including a time constant capacitor. A PWM comparator compares a difference signal between a feedback voltage and a preset reference voltage with the triangle wave signal to generate a PWM signal in response to the comparison result. A signal synchronizer sets a connection node between the time constant capacitor and the fundamental wave generator and an output terminal of the square wave signal in accordance with a power level of the LCD backlight. Also, a driving signal generator generates a driving signal in response to the square wave signal from the fundamental wave generator and the PWM signal from the PWM comparator. The driving circuit enables PWM controlling integrated circuits to be synchronized together.

Driving circuit for LCD backlight

A voltage controlled oscillator (VCO) for generating a clock of a 50% duty includes a VCO unit and a duty correction unit. The VCO unit generates first and second signals having a 180&#xb0; phase difference to each other with an oscillation frequency according to a control voltage to output the first and second signals through first and second oscillation output terminals. The duty correction unit generates a clock signal of a 50% duty according to the first and second signals through the first and second oscillation terminals.

Voltage controlled oscillator with duty correction

The present invention relates to a frequency-control-type piezo actuator driving circuit. The frequency-control-type piezo actuator driving circuit includes a piezo actuator that is driven by a constant amplitude of driving voltage pulse; a piezo driver that is connected to the piezo actuator so as to drive the piezo actuator; a frequency controller that is connected to the piezo driver so as to measure currents consumed when the piezo driver drives the piezo actuator, to detect a frequency corresponding to the maximum current among the measured currents, and to generate a frequency control signal corresponding to the detected frequency; and a frequency synthesizer that fixes a frequency of the piezo actuator in accordance with the frequency control signal of the frequency controller and generates the fixed frequency to the piezo driver.

Frequency-control-type piezo actuator driving circuit and method of driving the same

A liquid crystal display backlight inverter including a first error amplifying unit receiving and comparing a first detection voltage corresponding to a current flowing through a lamp with a first preset reference voltage and outputting a first error voltage corresponding to an error therebetween; a second error amplifying unit receiving and comparing a second detection voltage corresponding to a voltage applied to the lamp with a second preset reference voltage and outputting a second error voltage corresponding to an error therebetween; a feedback selector selecting one of the outputs of the first and second error amplifying unit according to an error between the second detection voltage and a third preset reference voltage; and a lamp control pulse generator generating a pulse signal having a duty controlled according to one of the first error voltage and second error voltage.

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Gyunggi-do, South Korea

Sang Cheol Shin