Abstract: 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.

Abstract: The invention provides an LED backlight drive circuit, an LCD device and a driving method. The LED backlight drive circuit comprises a plurality of LED lightbars which are arranged in parallel connection, and a detection module; a comparison unit is arranged in said detection module, the comparison ends of the comparison unit are respectively coupled to the output ends of the LED lightbars, and the reference end thereof is coupled with an adjustable reference voltage module. In the invention, because the comparison unit is used, and the reference end of the comparison unit is coupled to an adjustable reference voltage module, different reference voltages are selected in accordance with different output end voltages of the LED lightbars of the LCD device. If the voltage difference between the output end voltage of the LED lightbar and the reference voltage is controlled within a reasonable range, the comparison accuracy can be effectively improved.

Abstract: 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.

Abstract: 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.

Abstract: The present invention provides a driving circuit of a backlight module and a display apparatus using the same. The driving circuit comprises at least one transistor connected to light-emitting diodes (LEDs), a constant-current circuit connected to the transistor, a power resist connected to the transistor in parallel; and a power switch connected between the transistor and the power resist, wherein a switch signal is transmitted to the power switch, and a signal level of the switch signal in a three-dimensional (3D) image mode is higher than another signal level of the switch signal in a two-dimensional (2D) image mode. The present invention can be applicable to the display apparatus for raising a brightness of the backlight module in the 3D image mode.

Abstract: 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.

Abstract: The present invention discloses a LED backlight driving method, a LED backlight driving circuit and a liquid crystal display (LCD) device, wherein said LED backlight driving method comprises the following steps: detecting the voltage and the current of each LED string, calculating the power of each LED string, and determining the reference power; and regulating the output power of each LED string until the output power is equal to said reference power. Because the present invention uses the constant power control mode, the LED brightness decline caused by heat can be compensated on the one hand; on the other hand, by automatically regulating the voltage and the current of the light bar, the current at high voltage drop becomes low, and the current at low voltage drop becomes high. Thus, there is a reduction of the consumption of the constant-current control circuit caused by different voltage drops and a reduction of the temperature.

Abstract: An LED backlight drive circuit comprises a plurality of LED lamp strings connected in parallel, a constant-current control circuit for controlling magnitudes of currents flowing through the LED lamp strings to be the same, and a plurality of constant-voltage units. The number of the constant-voltage units is the same as that of the LED lamp strings. The constant-voltage units are connected between the LED lamp strings and the constant-current control circuit respectively. Each constant-voltage units comprises an MOS transistor and a first operational amplifier. The MOS transistor has a drain connected to a cathode of a corresponding LED lamp strings, a gate connected to an output terminal of the first operational amplifier and a source connected to the constant-current control circuit. The first operational amplifier has a positive input terminal connected to a reference voltage and an inverting input terminal connected to the source of the MOS transistor.

Abstract: 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.

Abstract: 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.

Abstract: 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.