KR20110071429A - Apparatus and method for driving of light emitting diode, and liquid crystal display device using the same - Google Patents

Abstract

PURPOSE: A light emitting diode driving device, a driving method thereof, and a liquid crystal display device using the same are provided to prevent the damage of a driving device due to the overcurrent by detecting at least one of feedback voltages to turn off a driving power generation unit. CONSTITUTION: A light emitting diode array(100) includes a plurality of light emitting diodes which are serially connected to each other. A driving power generation unit(200) supplies a driving power source to a light emitting diode array. A switching element(Q) controls the current which flows from the light emitting diode array to a base power source. A light emitting diode driving unit(300) generates a current control signal for controlling the switching of the switching element. The light emitting diode driving unit controls a driving operation of the driving power generation unit according to a voltage level of the current control signal.

Description

A driving device and a driving method of a light emitting diode, and a liquid crystal display device using the same {APPARATUS AND METHOD FOR DRIVING OF LIGHT EMITTING DIODE, AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device and a liquid crystal display of a light emitting diode, and more particularly, to detect an overcurrent flowing in a light emitting diode array and to stop driving of the driving power generation unit, thereby preventing damage caused by overcurrent. A driving device and a driving method, and a liquid crystal display device using the same.

The Back Light Unit is a device that illuminates a liquid crystal display panel. In the past, a cold cathode ray tube lamp (CCFL) was used as a light source. The response speed is about 15ms and the color reproducibility is about 75% lower than that of NTSC. In addition, since various problems, such as generating a predetermined white light occurs, in recent years, a light emitting diode (LED) element has been in the spotlight as a light source.

Compared with the cold cathode tube lamp, the light emitting diode is environmentally friendly, has a response speed of several nanoseconds, enables high-speed response, impulse driving, and color reproducibility of 80% to 100% or more. In addition, the light emitting diode has an advantage that the brightness and color temperature of the backlight can be arbitrarily adjusted by adjusting the amount of light.

The driving device for turning on such a light emitting diode includes a light emitting diode array in which a plurality of light emitting diodes are electrically connected in series.

1 is a circuit diagram schematically showing a driving device of a light emitting diode according to the prior art.

Referring to FIG. 1, the LED array driving apparatus according to the related art includes a light emitting diode array 10, a driving power generator 20, a switching element Q, a resistor Rs, and a light emitting diode driver 30. Equipped.

The light emitting diode array 10 includes a plurality of light emitting diodes (LEDs) electrically connected in series. Since the LED array 10 has a forward voltage deviation for each LED connected in series, the LED array 10 must be driven with a constant current.

The driving power generation unit 20 generates driving power Vd necessary for driving the LED array 10 under the control of the LED driving unit 30 using the input power Vin, and generates the generated driving power ( Vd) is supplied to the light emitting diode array 10.

The switching element Q is connected between the other end of the LED array 10 and the first node N1. The switching element Q is switched according to the current control signal CCS output from the light emitting diode driver 30 to control the amount of current flowing from the light emitting diode array 10 to the first node N1.

The resistor Rs is connected between the first node N1 and the base power source GND so that a voltage corresponding to a current flowing from the switching element Q to the base power source GND via the first node N1 is zero. One node N1 is detected.

The LED driver 30 controls the driving power generator 20 according to a light emitting diode dimming signal supplied from the outside, thereby controlling the driving power Vd supplied from the driving power generator 20 to the LED array 10. Control the level.

In addition, the LED driver 30 senses the current i1 flowing in the LED array 10 by using the feedback voltage Vfb applied to the first node N1 by the resistor Rs and switching device Q. The current i1 flowing through each light emitting diode array 10 is controlled by controlling the switching of.

However, according to the LED array driving apparatus according to the related art, the current flowing through the LED array 10 is controlled by using the switching element Q. When the switching element Q is shorted, the LED is short. As the current flows through the array 10, the lifetime of the light emitting diode is shortened, and the driving device may be damaged due to the overcurrent and overheating of the light emitting diode (LED).

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a driving device and a driving method of a light emitting diode capable of detecting an overcurrent flowing in a light emitting diode array and stopping driving of the driving power generation unit to prevent damage caused by an overcurrent, and the same. It is a technical subject to provide the used liquid crystal display device.

According to an aspect of the present invention, there is provided a light emitting diode driving apparatus including: a light emitting diode array in which a plurality of light emitting diodes are connected in series; A driving power generator for supplying driving power to the light emitting diode array; A switching element for controlling a current flowing from the light emitting diode array to a ground power source; And generating a current control signal for controlling switching of the switching element by using a feedback voltage corresponding to the current flowing to the base power, and controlling driving of the driving power generation unit according to the voltage level of the current control signal. It comprises a light emitting diode driver.

According to another aspect of the present invention, there is provided a method of driving a light emitting diode, the method comprising: driving a driving power generator to supply driving power to an electrically connected LED array; Controlling switching of a switching element connected between the other end of the light emitting diode array and a base power source to allow a current to flow in the light emitting diode array; Generating a current control signal using a feedback voltage corresponding to the current flowing to the base power source and a first reference voltage, and controlling switching of the switching element according to the current control signal; And controlling driving of the driving power generator in accordance with the voltage level of the current control signal.

According to an aspect of the present invention, there is provided a liquid crystal display device including: a display panel including a plurality of liquid crystal cells formed in respective regions defined by intersections of a plurality of gate lines and a plurality of data lines; A panel driver which displays an image corresponding to input data from outside on the display panel; And a backlight unit having a driving device for emitting light to the display panel, wherein the driving device includes: a light emitting diode array in which a plurality of light emitting diodes are connected in series; A driving power generator for supplying driving power to the light emitting diode array; A switching element for controlling a current flowing from the light emitting diode array to a ground power source; And generating a current control signal for controlling switching of the switching element by using a feedback voltage corresponding to the current flowing to the base power, and controlling driving of the driving power generation unit according to the voltage level of the current control signal. It comprises a light emitting diode driver.

As described above, the driving apparatus and driving method of the light emitting diode according to the present invention, and the liquid crystal display device using the same, are connected to the base power supply through a current control signal and a switching element for switching the switching element controlling the current flowing in the LED array. By detecting at least one of the feedback voltages corresponding to the flowing current and turning off the driving power generation unit, damage to the driving apparatus due to overcurrent can be prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view for schematically explaining a driving device of a light emitting diode according to a first embodiment of the present invention.

2, a driving apparatus of a light emitting diode according to a first embodiment of the present invention includes a light emitting diode array 100 and a driving power generator 200; It includes a switching element (Q), a resistor (Rs) and the light emitting diode driver 300.

The light emitting diode array 100 includes a plurality of light emitting diodes (LEDs) electrically connected in series.

The driving power generation unit 200 generates and generates driving power Vd for driving the LED array 100 under the control of the driving control unit 240 using the input power Vin supplied from the outside. The supplied driving power supply Vd to the LED array 100.

The switching element Q is connected between the other end of the LED array 100 and the ground power source GND. The switching element Q is switched according to the current control signal CCS supplied from the light emitting diode driver 200, and the amount of current flowing from the light emitting diode array 100 to the base power supply GND through the resistor Rs. To control.

The resistor Rs is connected between the first node N1 connected to the switching element Q and the base power source GND to the base power source GND via the first node N1 from the switching element Q. The voltage corresponding to the flowing current is detected at the first node N1.

Although not shown, the LED driver 300 controls the driving power generator 200 according to a light emitting diode dimming signal supplied from the outside, thereby driving power supplied from the driving power generator 200 to the LED array 100. Control the level of (Vd).

In addition, the LED driver 300 generates a current control signal CCS for controlling switching of the switching element Q by using a feedback voltage Vfb corresponding to the current flowing to the base power source GND. The driving of the driving power generation unit 200 is controlled according to the voltage level of the current control signal CCS. To this end, the LED driver 300 includes a current controller 310 and a driving power controller 320.

The current controller 310 generates a current control signal CCS using the first reference voltage V1 and the feedback voltage Vfb. To this end, the current controller 310 includes a non-inverting terminal (+) to which the first reference voltage V1 is supplied, an inverting terminal (-) to which a feedback voltage Vfb detected to the first node N1 is supplied, and The output terminal connected to the control terminal of the switching element Q is comprised.

The current controller 310 operates as a voltage follower having a first reference voltage V1, and according to a voltage level of the first reference voltage V1 and the feedback voltage Vfb, By generating the CCS and outputting it to the control terminal of the switching element Q, the switching of the switching element Q is controlled to control the current flowing in the LED array 100.

The driving power control unit 320 turns on / on driving of the driving power generation unit 200 by using the voltage level of the second reference voltage V2 and the current control signal CCS output from the current control unit 310. Off. To this end, the driving power control unit 320 includes a non-inverting terminal (+) to which the second reference voltage V2 is supplied, an inverting terminal (-) to which a current control signal CCS output from the current control unit 310 is supplied, And an output terminal connected to the driving power generator 200. Here, the second reference voltage V2 may be set to a voltage lower than a current flowing during normal light emission of the LED array 100. For example, the second reference voltage V2 may be set to the base power supply GND or 0.1V.

The driving power control unit 320 operates as a voltage follower having a second reference voltage V2 and supplies a power on / off signal according to the voltage level of the second reference voltage V2 and the current control signal CCS. It generates and turns on / off the driving of the driving power generation unit 200. For example, only when the voltage level of the current control signal CCS is lower than the second reference voltage V2, the power on / off signal in the first logic state is generated to turn off the driving of the driving power generator 200. . That is, when overcurrent flows to the LED array 100 due to a short of the switching element Q, the voltage of the first node N1 becomes higher than the base power supply GND, and accordingly, from the current controller 310, The voltage level of the output current control signal CCS drops to the base power supply GND or less. Accordingly, the driving power control unit 320 detects a case where the voltage level of the current control signal CCS is lower than the second reference voltage V2 and turns off the driving power generation unit 200.

As such, the driving device of the LED according to the first embodiment of the present invention detects the voltage level of the current control signal CCS output from the current controller 310 even when the switching element Q is not properly operated. By turning off the driving power generator 200, damage to the driving device due to overcurrent can be prevented.

3 is a diagram for schematically describing a driving device of a light emitting diode according to a second exemplary embodiment of the present invention.

Referring to FIG. 3, a driving device of a light emitting diode according to a second embodiment of the present invention includes a light emitting diode array 100 and a driving power generator 200; It includes a switching element (Q), a resistor (Rs) and the light emitting diode driver 300, the rest of the configuration except for the light emitting diode driver 300 is the same as the driving device of the light emitting diode according to the first embodiment described above Therefore, the description of the same configuration will be replaced by the above description, and the same reference numerals will be given.

The LED driver 300 includes a current controller 310 and first to third drive power controllers 320, 330, and 340.

The current controller 310 generates a current control signal CCS using the first reference voltage V1 and the feedback voltage Vfb. To this end, the current controller 310 includes a non-inverting terminal (+) to which the first reference voltage V1 is supplied, an inverting terminal (-) to which a feedback voltage Vfb detected to the first node N1 is supplied, and The output terminal connected to the control terminal of the switching element Q is comprised.

The current controller 310 operates as a voltage follower having a first reference voltage V1 and generates a current control signal CCS according to the voltage levels of the first reference voltage V1 and the feedback voltage Vfb. By controlling the switching of the switching element (Q) by outputting to the control terminal of the switching element (Q) to control the current flowing through the light emitting diode array (100).

The first driving power control unit 320 generates the first power on / off signal PS1 using the voltage level of the second reference voltage V2 and the current control signal CCS output from the current control unit 310. . To this end, the driving power control unit 320 includes a non-inverting terminal (+) to which the second reference voltage V2 is supplied, an inverting terminal (-) to which a current control signal CCS output from the current control unit 310 is supplied, And an output terminal connected to the third driving power control unit 340. Here, the second reference voltage V2 may be set to a voltage lower than a current flowing during normal light emission of the LED array 100. For example, the second reference voltage V2 may be set to the base power supply GND or 0.1V.

The first driving power control unit 320 operates as a voltage follower having a second reference voltage V2. The first driving power control unit 320 operates the first power on according to the voltage level of the second reference voltage V2 and the current control signal CCS. Generate the on / off signal PS1. For example, the first power on / off signal PS1 of the first logic state is generated only when the voltage level of the current control signal CCS is smaller than the second reference voltage V2. That is, when overcurrent flows to the LED array 100 due to a short of the switching element Q, the voltage of the first node N1 becomes higher than the base power supply GND, and accordingly, from the current controller 310, The voltage level of the output current control signal CCS falls below the base power supply GND. Therefore, the first driving power control unit 320 generates the first power on / off signal PS1 in the first logic state only when the voltage level of the current control signal CCS is lower than the second reference voltage V2. .

The second driving power control unit 330 generates the second power on / off signal PS2 using the third reference voltage V3 and the feedback voltage Vfb detected at the first node N1. To this end, the second driving power control unit 330 is an inverting terminal (-) to which the third reference voltage V3 is supplied and a non-inverting terminal (+) to which the feedback voltage Vfb detected to the first node N1 is supplied. ) And an output terminal connected to the third driving power control unit 340. Here, the third reference voltage V3 may be set to a voltage higher than a current flowing during normal light emission of the LED array 100.

The second driving power control unit 330 operates as a voltage follower having a third reference voltage V3, and according to the voltage levels of the third reference voltage V3 and the feedback voltage Vfb, the second power supply on / off is controlled. Generate off signal PS2. For example, the second power on / off signal PS2 of the first logic state is generated only when the voltage level of the feedback voltage Vfb is higher than the third reference voltage V3. That is, when overcurrent flows through the LED array 100 due to a short of the switching element Q, the voltage of the first node N1 becomes higher than the base power supply GND. Accordingly, the second driving power control unit 330 generates the second power on / off signal PS2 in the first logic state only when the feedback voltage Vfb is higher than the third reference voltage V3.

The fourth driving power controller 340 is the first power on / off signal PS1 supplied from the second driving power controller 320 and the second power on / off signal supplied from the third driving power controller 330. According to PS2, the driving of the driving power generator 200 is turned on / off. Here, the fourth driving power control unit 340 may be formed of an AND gate having two input terminals and one output terminal. Accordingly, the fourth driving power controller 340 is supplied with the first and second power on / off signals PS1 and PS2 in the first logic state to the second and third driving power controllers 320 and 330, respectively. Only when the drive of the power generator 200 is turned off.

As described above, the driving device of the LED according to the second embodiment of the present invention detects the voltage level of the current control signal CCS output from the current controller 310 even when the switching element Q is not properly operated. In addition, by detecting the overcurrent flowing in the first node N1 and turning off the driving power generator 200, damage to the driving apparatus due to the overcurrent can be prevented. That is, according to the second embodiment of the present invention, the driving power generator 200 only when the voltage level of the current control signal CCS drops to the base power supply GND and an overcurrent of a predetermined current or more flows in the LED array 100. Will be turned off.

Therefore, the driving apparatus of the LED according to the second embodiment of the present invention can efficiently control the stopping of the driving power generator 200 while maintaining a constant current flowing in the LED array 100.

Meanwhile, in the above-described embodiment of the present invention, a single light emitting diode array 100 in which a plurality of light emitting diodes (LEDs) are electrically connected is illustrated, but not limited thereto, but is not limited thereto. The plurality of LEDs may be connected in parallel to correspond to the number of channels according to the driving capability of the LED driver 300.

4 is a view for explaining a liquid crystal display device using a driving device of a light emitting diode according to an exemplary embodiment of the present invention.

Referring to FIG. 4, a liquid crystal display according to an exemplary embodiment of the present invention includes a display panel 400, a panel driver 500, and a backlight unit 600.

The display panel 400 includes a plurality of pixels P formed in each region defined by the plurality of gate lines GL and the plurality of data lines DL.

Each of the plurality of pixels P includes a thin film transistor (not shown) connected to the gate line GL and the data line DL, and a liquid crystal cell connected to the thin film transistor.

The display panel 400 displays a predetermined image by forming an electric field in the liquid crystal cell according to the pixel voltage supplied to each pixel P to adjust the transmittance of light emitted from the backlight unit 600.

The panel driver 500 includes a data driver circuit 510, a gate driver circuit 520, and a timing controller 530.

The data driving circuit unit 510 latches the data signals R, G, and B input from the timing control unit 530 according to the data control signal DCS supplied from the timing control unit 530, and performs analog positive / negative polarity. After the latched data signal is converted to the positive / negative analog pixel voltage using the gamma voltage, a pixel voltage having a polarity corresponding to the polarity control signal is generated and supplied to the data lines DL.

The gate driving circuit unit 520 generates gate pulses according to the gate control signal GCS supplied from the timing controller 530 and sequentially supplies the gate pulses to the gate lines GL. Here, the gate driving circuit unit 520 may be formed on the substrate at the same time as the thin film transistor is formed.

The timing controller 530 arranges the input data RGB, which is input from the outside, to be suitable for driving the display panel 400 and supplies the input data RGB to the data driver circuit 510.

In addition, the timing controller 530 controls the operation timing of the data driver circuit unit 510 and the gate driver circuit unit 520 by using the input timing synchronization signal TSS. GCS).

The timing synchronization signal TSS is a vertical synchronization signal Vsync; Horizontal synchronization signal (Hsync); A data enable signal; And a dot clock DCLK.

The data control signal DCS includes a source start pulse; A source sampling clock; Source Output Enable; And a polarity control signal POL.

The gate control signal GCS may include a gate start pulse; Gate Shift Clock; And a gate output enable.

The backlight unit 600 irradiates light to the display panel 400 using a light emitting diode. To this end, the backlight unit 600 is configured to include a light emitting diode driving apparatus according to an embodiment of the present invention shown in Figs. 2 and 3 will be replaced with the above description.

The liquid crystal display according to the exemplary embodiment of the present invention detects an overcurrent flowing in the LED array 100 and stops driving of the backlight unit 600, thereby preventing damage caused by the overcurrent.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

1 is a circuit diagram schematically showing a driving device of a light emitting diode according to the prior art.

2 is a view for schematically explaining a driving device of a light emitting diode according to a first embodiment of the present invention.

3 is a diagram for schematically describing a driving device of a light emitting diode according to a second exemplary embodiment of the present invention.

FIG. 4 is a diagram schematically illustrating a liquid crystal display using a driving device of a light emitting diode according to an exemplary embodiment of the present disclosure.

<Explanation of Signs of Major Parts of Drawings>

100: LED array 200: driving power generation unit

300: light emitting diode driver 310: current control unit

320: driving power control unit 330: second driving power control unit

340: third driving power control unit 400: display panel

500: panel driver 510: data driver circuit

520: gate driving circuit unit 530: timing control unit

600: backlight unit

Claims (10)

A light emitting diode array in which a plurality of light emitting diodes are connected in series; A driving power generator for supplying driving power to the light emitting diode array; A switching element for controlling a current flowing from the light emitting diode array to a ground power source; And Light emission for generating a current control signal for controlling the switching of the switching element using a feedback voltage corresponding to the current flowing to the base power and controlling the driving of the driving power generation unit according to the voltage level of the current control signal. Driving device for a light emitting diode comprising a diode driving unit. The method of claim 1, The light emitting diode driver, A current controller configured to generate the current control signal using a first reference voltage and the feedback voltage; And And a driving power controller configured to turn on / off driving of the driving power generator by using a second reference voltage and a voltage level of the current control signal output from the current controller. Driving device of light emitting diode. The method of claim 2, And the driving power control unit turns off the driving of the driving power generation unit when the voltage level of the current control signal is lower than the second reference voltage. The method of claim 1, The light emitting diode driver, A current controller configured to generate the current control signal using a first reference voltage and the feedback voltage; And A first driving power controller configured to generate a first power on / off signal using a second reference voltage and a voltage level of the current control signal output from the current controller; A second driving power controller configured to generate a second power on / off signal using a third reference voltage and the feedback voltage; And And a third driving power control unit configured to turn on / off driving of the driving power generation unit in response to the first and second power on / off signals. The method of claim 4, wherein The first driving power control unit generates a first power on / off signal in a first logic state when the voltage level of the current control signal is lower than the second reference voltage. The second driving power controller generates a second power on / off signal in a first logic state when the voltage level of the feedback voltage is higher than the third reference voltage. And the third driving power control unit turns off the driving of the driving power generation unit according to the first and second power on / off signals in the first logic state. Supplying driving power to a light emitting diode array in which a plurality of light emitting diodes are connected in series by driving the driving power generator; Controlling switching of a switching element connected between the other end of the light emitting diode array and a base power source to allow a current to flow in the light emitting diode array; Generating a current control signal using a feedback voltage corresponding to the current flowing to the base power source and a first reference voltage, and controlling switching of the switching element according to the current control signal; And And controlling the driving of the driving power generator in accordance with the voltage level of the current control signal. The method of claim 6, The controlling of driving of the driving power generation unit may include driving off the driving power generation unit when the voltage level of the current control signal is lower than a second reference voltage. The method of claim 6, Controlling the driving of the driving power generation unit Generating a first power on / off signal using a second reference voltage and a voltage level of the current control signal; Generating a second power on / off signal using a third reference voltage and the feedback voltage; And And driving on / off the driving of the driving power generation unit in response to the first and second power on / off signals. The method of claim 8, The turning on / off of the driving power generator may include a first power on / off signal of a first logic state generated when the voltage level of the current control signal is lower than the second reference voltage, and the feedback voltage. And driving off the driving power generator in accordance with a second power on / off signal in a first logic state generated when the voltage level is higher than the third reference voltage. A display panel including a plurality of liquid crystal cells formed in respective regions defined by intersections of the plurality of gate lines and the plurality of data lines; A panel driver which displays an image corresponding to input data from outside on the display panel; And A backlight unit for irradiating light to the display panel; The backlight unit includes a driving device of the light emitting diode according to any one of claims 1 to 5, characterized in that the liquid crystal display device.

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