Shenzhen China Star Optoelectronics Technology Co., Ltd.

Xinming Gao

Xiang Yang

Fei Li

The invention discloses an LED backlight drive circuit, an LCD device and a driving method. The LED backlight drive circuit includes a power source; an output capacitor and an LED lightbar which is connected in series with a first controllable switch are in parallel connection, and then are arranged between the output terminal and the ground terminal of the power source. The LED backlight drive circuit further includes a first comparator; a cathode of the first comparator is connected to a first reference voltage, an anode of the first comparator is coupled with the output terminal of the power source, and the output terminal of the first comparator is coupled with a control end of the first controllable switch; when the anode voltage of the first comparator exceeds the cathode voltage, the output terminal of the first comparator drives the first controllable switch to be conducted. In the invention, the LED lightbar only can be conducted at the predetermined voltage. Thus, the LED will be unable to be lighted even if the electric quantity is stored in the output capacitor; only when the output voltage achieves the predetermined voltage in the complete ON operation, the first controllable switch is able to be conducted, which solves the problem of LED blinking in the ON operation.

LED backlight drive circuit, liquid crystal display device and driving method

The present invention discloses an LCD backlight module, which includes a backlight source and a backlight source control device, the backlight source control device comprising: a first switch; a boost module; a control module, utilized to control the first switch, so that the backlight source is switched on off under the control of the control module, and utilized to control the boost module, so that the boost module keeps outputting the voltage after the backlight source is turned off by the first switch.

LCD backlight module and method for controlling the same

The present invention proposes a liquid crystal display device and a transforming circuit thereof. One terminal of a first coil connects to input voltage. One terminal of a energy-storage unit connects to the other terminal of the first coil. One terminal of a second coil connects to the other terminal of the energy-storage unit, and the other terminal of the second coil connects to the light source. An input terminal of a unidirectional unit connects to the one terminal of the first coil which is connected to the input voltage, and the output terminal connected to the one terminal of the second coil which is connected to the light source. A driving signal is fed into a controlling terminal of a switch unit. A first terminal of the switch unit is grounded, and the second terminal of the switch unit is connected a medial point between the first coil and the energy-storage unit.

LCD device and a transforming circuit thereof

The present disclosure discloses a light emitting diode (LED) backlight driving circuit, a backlight module, and a liquid crystal display (LCD) device. The LED backlight driving circuit includes an LED lightbars. An output end of the LED lightbar is connected with a control integrated circuit (IC) in series, and is also connected with a shunt controllable switch. The shunt controllable switch is switched on when a voltage of the output end of the LED lightbar exceeds a preset value and is switched off when the voltage is less than the preset value. In the present disclosure, because a shunt controllable switch is connected in parallel in the control IC, when the LED lightbars are short-circuited, the shunt controllable switch is switched on, a part of current flows towards the shunt controllable switch, and the burden of the control IC is alleviated. Thus, the temperature of the control IC is reduced.

LED backlight driving circuit, backlight module, and LCD device

The invention provides an LED backlight driving circuit, a backlight module, and an LCD device. The LED backlight driving circuit includes an LED light string; an input end of the LED light string is directly connected with an input end of a power source, and an output end of the LED light string is coupled with a buck module. In the invention, because the output end of the LED light string is in series connected with the buck module, the LED light string is connected in series between an input voltage and an output voltage, and a part of LEDs are directly supplied by the input voltage without the first stage conversion. Thus, the energy supplied by the buck module is reduced, the conversion efficiency is improved, the energy efficiency is increased, the requirement of the buck module to withstand voltage is reduced, and the device standard is decreased, thereby favoring cost reduction.

The present invention provides an LED backlight system and display device. Backlight system includes power source module, LED array, master switch module, current detection module, current equalizer module and current shunt module. LED array is connected to power source module and includes LED strings with common anode. Master switch module includes first switch transistors for receiving switch control PWM signal of LED strings. Current detection module outputs current feedback signals corresponding to currents of LED strings. Current equalizer module is connected to current detection and includes equalizer control unit and equalizer switch unit. Based on current feedback signal, equalizer control unit controls on-and-off of equalizer switch unit. Current shunt module is connected in parallel with current equalizer module and performs current shunt on current equalizer module. As such, the present invention reduces energy-consumption of current equalizer module and temperature of LED drive chip.

LED backlight system and display device

A boost converter is disclosed in the present disclosure. The boost converter includes a switching element, a first diode, a second diode, a first inductor, a second inductor, a DC voltage input terminal and a DC voltage output terminal. The first inductor, the second inductor and the second diode are connected in sequence between the DC voltage input terminal and the DC voltage output terminal. The second diode has an anode connected to the second inductor and a cathode connected to the DC voltage output terminal. The switching element includes a first end, a second end and a third end for controlling connection or disconnection between the first end and the second end. The first end is connected between the first and the second inductor. The boost converter of the present disclosure is convenient to use and features high inductance coupling efficiency.

Boost converter

A method for driving the backlight unit of the liquid crystal display includes: comparing the strength of a soft start signal with a predetermined signal through a comparator circuit, and generating a first comparison signal or a second comparison signal according to the comparison result; outputting a first frequency from a frequency modulation circuit according to the first comparison signal; and increasing the rising rate of the output voltage of a boost converter according to the first frequency. Therefore, the rising rate of the output voltage is increased, thereby solving the screen-flickering problem.

Driving method for backlight unit of liquid crystal display and system thereof

A pulse width modulation (PWM) dimming circuit comprises a switch unit, a current generation unit, a mirror current source, a multi-path output unit, a plurality of current balance units and a plurality of LED lamp strings. The switch unit receives a PWM signal which controls the switch on or off. The current generation unit is connected with the switch unit and generates a current of a predetermined magnitude when the switch unit is on. The mirror current source is connected with the current generation unit and receives the current to generate a mirror current. The multi-path output unit is connected with the mirror current source and receives and output the mirror current in multiple paths. The current balance units are connected between the multi-path output unit and the LED lamp strings respectively. The PWM dimming circuit decreases both the difficulty and the manufacturing cost and is easy to operate.

PWM dimming circuit with multiple outputting paths of current for multiple LED strings

The invention discloses an LED backlight driving circuit, an LCD device and a driving circuit. The LED backlight driving circuit includes a power supply module, an LED lightbar coupled with an output terminal of the power supply module, a dimming module coupled with the output terminal of the LED lightbar, and the LED backlight driving circuit further includes a transfer switch. A first input terminal of the transfer switch is coupled to the output terminal of the LED lightbar, and a second input terminal of the transfer switch is coupled to a feedback voltage. The output terminal of the transfer switch is coupled to the power supply module. The transfer switch is switched to the first input terminal when the dimming module is ON, and the transfer switch is switched to the second input terminal when the dimming module is OFF. Therefore, the LEDs of the invention can operate normally within the short dimming cycle. The invention only adds one transfer switch, the circuit is simple and does not increase the circuit area, and the cost is low.

LED backlight driving circuit, liquid crystal display device and driving circuit

A light emitting diode (LED) backlight driving circuit is disclosed in the present disclosure. The LED backlight driving circuit in configured to power an LED backlight module, and comprises: a voltage stabilizing circuit, being configured to receive an input voltage and filter the input voltage to output a stabilized direct current (DC) voltage; a first boost circuit and a second boost circuit connected with the voltage stabilizing circuit respectively, being configured to receive the stabilized DC voltage and boost the stabilized DC voltage for output to the LED backlight module; and a selection control circuit, being configured to alternately select one of the first boost circuit and the second boost circuit to power the LED backlight module. The LED backlight driving circuit of the present disclosure can improve the voltage boosting efficiency and reduce the cost, so it is of great utility.

LED backlight driving circuit

The present invention discloses a LED backlight driving method, a LCD device and a LED backlight driving circuit, wherein the LED backlight driving method comprises the following steps: regulating the current of each LED string so that the voltages of all LED strings are equal; and regulating the duty cycle of the current of the corresponding LED string so that the effective value of the current of each LED string meets the preset requirement of brightness. The present invention solves the problem of consumption caused by voltage difference by regulating the current through the current regulation module to ensure that the voltages of all the LED strings are equal, and ensures the brightness consistency by regulating the duty cycle through the duty-cycle regulation module so that the effective value of the currents of all the LED strings are equal.

Growing community of inventors

Shenzhen, China

Xinming Gao