KR101221210B1 - Hybrid backlight unit of LCD and drive method thereof - Google Patents

Abstract

The present invention provides a hybrid backlight unit that can arbitrarily adjust the color temperature of a liquid crystal display device generated by light emitting diodes, the light emitting diode driver for converting an input voltage into a light emitting diode driving voltage and supplying it; A plurality of light emitting diode strings driven by the light emitting diode driving voltages supplied from the light emitting diode drivers to emit light; Color temperature control means for controlling the color temperature of the plurality of light emitting diode strings to generate a color temperature corresponding to a color temperature level set by a user; And a driving voltage varying means for varying a level of a light emitting diode driving voltage output from the light emitting diode driver and supplying the plurality of light emitting diode strings under the control of the color temperature control means. A first driving voltage varying unit configured to vary a level of a light emitting diode driving voltage output from the light emitting diode driver and to supply one end of the plurality of light emitting diode strings according to a control of a color temperature control means; And a second driving voltage varying unit configured to vary the level of the light emitting diode driving voltage output from the light emitting diode driver according to the control of the color temperature control means and to supply the other end of the plurality of light emitting diode strings.

LCD, backlight, light emitting diode, color temperature

Description

Hybrid backlight unit of liquid crystal display device and driving method thereof

1 is an equivalent circuit diagram of a pixel formed in a general liquid crystal display device.

2 is a block diagram of a general liquid crystal display device.

3 is a block diagram of a hybrid backlight unit of a conventional liquid crystal display device.

4 is a view showing an arrangement of light emitting diode strings provided in a hybrid backlight unit of a conventional liquid crystal display device.

5 is a block diagram of a hybrid backlight unit of a liquid crystal display device according to an exemplary embodiment of the present invention.

6 is a view showing an arrangement of light emitting diode strings provided in a hybrid backlight unit of a liquid crystal display of the present invention.

7 is a flowchart illustrating a method of driving a hybrid backlight unit of a liquid crystal display according to an exemplary embodiment of the present invention.

The present invention relates to a hybrid backlight unit of a liquid crystal display device, and more particularly, to a hybrid backlight unit capable of arbitrarily adjusting the color temperature of a liquid crystal display device generated by light emitting diodes and a driving method thereof.

The liquid crystal display device displays an image by adjusting the light transmittance of the liquid crystal cells according to the video signal, and the active matrix type liquid crystal display device in which the switching elements are formed for each liquid crystal cell enables active control of the switching elements. This is advantageous for video implementation. As a switching device used in the active matrix liquid crystal display device, a thin film transistor (hereinafter, referred to as TFT) is mainly used as shown in FIG. 1.

Referring to FIG. 1, an active matrix type liquid crystal display device converts digital input data into an analog data voltage based on a gamma reference voltage and supplies it to the data line DL and simultaneously supplies scan pulses to the gate line GL. The liquid crystal cell Clc is charged.

The gate electrode of the TFT is connected to the gate line GL, the source electrode is connected to the data line DL, and the drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell Clc and one electrode of the storage capacitor Cst. Connected.

A common voltage Vcom is supplied to the common electrode of the liquid crystal cell Clc.

The storage capacitor Cst serves to charge the data voltage applied from the data line DL when the TFT is turned on to maintain the voltage of the liquid crystal cell Clc constant.

When a scan pulse is applied to the gate line GL, the TFT is turned on to form a channel between the source electrode and the drain electrode to apply a voltage on the data line DL to the pixel electrode of the liquid crystal cell Clc Supply. At this time, the liquid crystal molecules of the liquid crystal cell Clc modulate the incident light by changing the arrangement by the electric field between the pixel electrode and the common electrode.

A configuration of a conventional liquid crystal display device having pixels having such a structure will be described with reference to FIG. 2.

2 is a configuration diagram of a general liquid crystal display device.

Referring to FIG. 2, the liquid crystal display device 100 includes a thin film transistor TFT for driving data lines DL1 to DLm and gate lines GL1 to GLn and driving the liquid crystal cell Clc at an intersection thereof. A liquid crystal display panel 110 having a thin film transistor, a data driver 120 for supplying data to the data lines DL1 to DLm of the liquid crystal display panel 110, and a gate of the liquid crystal display panel 110. A gate driver 130 for supplying scan pulses to the lines GL1 to GLn, a gamma reference voltage generator 140 for generating a gamma reference voltage and supplying it to the data driver 120, and a liquid crystal display panel 110. ), The backlight assembly 150 for irradiating light, the inverter 160 for applying an alternating voltage and current to the backlight assembly 150, and the common voltage Vcom are generated to generate the liquid crystal of the liquid crystal display panel 110. A common voltage generator 170 for supplying the common electrode of the cell Clc, A timing for controlling the gate driving voltage generator 180 for generating the high voltage VGH and the gate low voltage VGL and supplying the gate voltage 130 to the gate driver 130, and for controlling the data driver 120 and the gate driver 130. The controller 190 is provided.

In the liquid crystal display panel 110, liquid crystal is injected between two glass substrates. On the lower glass substrate of the liquid crystal display panel 110, the data lines DL1 to DLm and the gate lines GL1 to GLn are orthogonal. TFTs are formed at intersections of the data lines DL1 to DLm and the gate lines GL1 to GLn. The TFT supplies the data on the data lines DL1 to DLm to the liquid crystal cell Clc in response to the scan pulse. The gate electrodes of the TFTs are connected to the gate lines GL1 to GLn, and the source electrodes of the TFTs are connected to the data lines DL1 to DLm. The drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell Clc and the storage capacitor Cst.

The TFT is turned on in response to the scan pulse supplied to the gate terminal via the gate lines GL1 to GLn. When the TFT is turned on, video data on the data lines DL1 to DLm is supplied to the pixel electrode of the liquid crystal cell Clc.

The data driver 120 supplies data to the data lines DL1 to DLm in response to the data driving control signal DDC supplied from the timing controller 190, and digital video data supplied from the timing controller 190. After sampling and latching the RGB, the liquid crystal cell Clc of the liquid crystal display panel 110 is converted into an analog data voltage capable of expressing gray scale based on the gamma reference voltage supplied from the gamma reference voltage generator 140. Supply to the data lines DL1 to DLm.

The gate driver 130 sequentially generates scan pulses, that is, gate pulses, in response to the gate driving control signal GDC and the gate shift clock GSC supplied from the timing controller 190, thereby providing the gate lines GL1 to GLn. To feed. In this case, the gate driver 130 determines the high level voltage and the low level voltage of the scan pulse based on the gate high voltage VGH and the gate low voltage VGL supplied from the gate driving voltage generator 180.

The gamma reference voltage generator 140 receives the highest high potential power voltage VDD among the power voltages supplied to the liquid crystal display panel 110 to generate a positive gamma reference voltage and a negative gamma reference voltage to generate a data driver. 120).

The backlight assembly 150 is disposed on the rear surface of the liquid crystal display panel 110 and emits light by an AC voltage and a current supplied from the inverter 160 to irradiate light to each pixel of the liquid crystal display panel 110.

The inverter 160 converts the square wave signal generated therein into a triangular wave signal and compares the triangular wave signal with a DC power supply voltage (VCC) supplied from the system to generate a burst dimming signal proportional to the comparison result. . When a burst dimming signal determined according to an internal square wave signal is generated, a driving IC (not shown) for controlling the generation of AC voltage and current in the inverter 160 is supplied to the backlight assembly 150 according to the burst dimming signal. Control the generation of alternating voltage and current.

The common voltage generator 170 receives the high potential power voltage VDD to generate the common voltage Vcom and supplies the common voltage Vcom to the common electrodes of the liquid crystal cells Clc of each pixel of the liquid crystal display panel 110.

The gate driving voltage generator 180 receives the high potential power voltage VDD to generate the gate high voltage VGH and the gate low voltage VGL to supply the gate driver 130 to the gate driver 130. Here, the gate driving voltage generation unit 180 generates a gate high voltage VGH that is greater than or equal to the threshold voltage of the TFTs provided in each pixel of the liquid crystal display panel 110, and the gate low voltage that is less than or equal to the threshold voltage of the TFT. VGL). The gate high voltage VGH and the gate low voltage VGL thus generated are used to determine the high level voltage and the low level voltage of the scan pulse generated by the gate driver 130, respectively.

The timing controller 190 supplies digital video data RGB, which is supplied from a digital video card (not shown), to the data driver 120, and also horizontal / vertical synchronization signals H and V according to the clock signal CLK. The data driving control signal DDC and the gate driving control signal GDC may be generated and supplied to the data driver 120 and the gate driver 130, respectively. The data driving control signal DDC includes a source shift clock SSC, a source start pulse SSP, a polarity control signal POL, a source output enable signal SOE, and a gate driving control signal GDC. ) Includes a gate start pulse (GSP) and a gate output enable (GOE).

The conventional liquid crystal display having the configuration as described above includes a hybrid backlight unit having a plurality of light emitting diode strings and a plurality of lamps, and the conventional hybrid backlight unit will be described as follows.

3 is a configuration diagram of a hybrid backlight unit of a conventional liquid crystal display device, and shows a plurality of light emitting diode strings and a driving device thereof. However, the lamps of the hybrid backlight unit are omitted because they do not contrast with the features of the present invention.

Referring to FIG. 3, the conventional hybrid backlight unit 200 includes a rectifier 210 and a rectifier 210 for converting a commercial power supply (for example, AC voltage 220V) into a DC voltage DC. Smoothing unit 220 to remove the ripple carried on the DC voltage changed by the power factor correction factor 230 to output a DC voltage (DC) 400V by correcting the power factor of the DC voltage output from the smoothing unit 220 And a DC / DC converter 240 for converting the DC voltage DC 400V output from the power factor correcting unit 230 into a DC voltage 24V and outputting the same to the inverter 160, and the DC / DC converter 240. And a light emitting diode driver 250 for converting the DC 400V applied from the light emitting diode into a light emitting diode driving voltage to supply the plurality of light emitting diode strings 260.

Here, each of the plurality of light emitting diode strings 260 is composed of a plurality of light emitting diodes LED1 connected in series. In particular, the plurality of light emitting diodes LED1 have the same peak wavelength but have a 490 nm peak wavelength. . The plurality of light emitting diode strings 260 are spaced apart at regular intervals in the horizontal direction as shown in FIG. 4, and the plurality of light emitting diodes LED1 are also spaced apart at regular intervals in the horizontal direction. do.

The rectifier 210 converts a commercial power supply (for example, AC voltage 220V) into a DC voltage DC to supply the smoothing unit 220. Since the boosting is performed during the rectification, the commercial power source is AC. In the case of 220V, approximately DC 331V is supplied to the smoothing unit 220.

The smoothing unit 220 removes the ripple on the DC voltage (DC 331V) rectified by the rectifying unit 210 and applies DC 331V including only the DC component to the power factor correcting unit 230. In this smoothing process, the DC component Pass the bay and absorb and remove the alternating current components.

The power factor correcting unit 230 removes the phase difference between the voltage and the current by correcting the power factor of the DC voltage (DC 331V) applied from the smoothing unit 220 and supplies DC 400V to the LED driver 250. The power factor correcting unit 230 is used to supply a constant DC voltage (DC 400V) to the LED driver 250 at all times, regardless of the size of the commercial power source because the commercial power source used in each country is different.

The DC / DC converter 240 converts the DC voltage 400V output from the power factor correcting unit 230 into a DC voltage 24V and supplies the same to the light emitting diode driver 250.

The LED driver 250 converts the DC high voltage (400 V) supplied from the DC / DC converter 240 into a DC low voltage (DC 35V) and supplies the same to the plurality of LED strings 260.

Here, the rectifier 210, the smoothing unit 220, the power factor correcting unit 230, and the DC / DC converter 240 are not provided in the liquid crystal display device 100, but are provided with a monitor to which the liquid crystal display device 100 is applied. On the power board (not shown) of a system such as a television receiver, a plurality of light emitting diode strings 260 are provided in the liquid crystal display device 100.

As described above, since the plurality of light emitting diode strings 260 are made of light emitting diodes having the same peak wavelength and the plurality of light emitting diode strings 260 are always supplied with a constant voltage, the plurality of light emitting diode strings The color temperature on the screen represented by fields 260 is always constant. For this reason, the conventional hybrid backlight unit is not only able to provide a color temperature suitable for the consumer's taste, but also requires a new installation of light emitting diodes having different peak wavelengths when buyers request a change in color temperature.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a hybrid backlight unit and a driving method thereof that can arbitrarily adjust the color temperature of the liquid crystal display device generated by the light emitting diodes.

An object of the present invention is to provide a hybrid backlight unit and a driving method thereof capable of displaying a color temperature suitable for a user's taste by arbitrarily adjusting the color temperature of a liquid crystal display device generated by light emitting diodes.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hybrid backlight unit and a driving method thereof, by which a color temperature of a liquid crystal display device generated by light emitting diodes is arbitrarily set in a manufacturing step, so that a color temperature required by a buyer or the like can be easily set.

The present invention for achieving the above object is a light emitting diode driver for converting the input voltage into a light emitting diode driving voltage to supply; A plurality of light emitting diode strings driven by the light emitting diode driving voltages supplied from the light emitting diode drivers to emit light; Color temperature control means for controlling the color temperature of the plurality of light emitting diode strings to generate a color temperature corresponding to a color temperature level set by a user; And a driving voltage varying means for varying a level of a light emitting diode driving voltage output from the light emitting diode driver and supplying the plurality of light emitting diode strings under the control of the color temperature control means.

The driving voltage varying means may include: a first driving voltage varying part configured to vary a level of a light emitting diode driving voltage output from the light emitting diode driver and to supply one end of the plurality of light emitting diode strings under the control of the color temperature control means; And a second driving voltage varying unit configured to vary the level of the light emitting diode driving voltage output from the light emitting diode driver and to supply the other end of the plurality of light emitting diode strings under the control of the color temperature control means.

The first driving voltage variable part includes a first variable resistor connected between a first output terminal of the light emitting diode driver and one end of the plurality of light emitting diode strings.

The second driving voltage variable part includes a second variable resistor connected between the second output terminal of the light emitting diode driver and the other end of the plurality of light emitting diode strings.

The color temperature control means reduces the variable resistance values of the first and second variable resistors when the color temperature level higher than the current color temperature is set, and sets the color resistance levels of the first and second variable resistors when the color temperature level lower than the current color temperature is set. It is characterized by increasing the variable resistance value.

Each of the plurality of light emitting diode strings may include a plurality of first light emitting diodes and a plurality of second light emitting diodes connected in series, and the first and second light emitting diodes may be alternately disposed.

The first light emitting diode has a longer peak wavelength than the second light emitting diode.

The first light emitting diode is characterized in that it has a 490nm peak wavelength.

The second light emitting diode is characterized in that it has a 430nm peak wavelength.

The present invention provides a light emitting diode driver for converting an input voltage into a light emitting diode driving voltage and supplying the same; A plurality of light emitting diode strings driven by the light emitting diode driving voltages supplied from the light emitting diode drivers to emit light; A first variable resistor connected between the first output terminal of the light emitting diode driver and one end of the plurality of light emitting diode strings to vary a level of the light emitting diode driving voltage output from the light emitting diode driver; And a second variable resistor connected between the second output terminal of the light emitting diode driver and the other end of the plurality of light emitting diode strings in order to vary the level of the light emitting diode driving voltage output from the light emitting diode driver. Herein, when the variable resistance of the first and second variable resistors is decreased, the color temperature of the plurality of light emitting diode strings is increased, and when the variable resistance of the first and second variable resistors is increased, the plurality of light emitting diode strings is increased. Their color temperature is reduced.

The present invention provides a light emitting diode driver for converting an input voltage into a light emitting diode driving voltage and supplying the same; A plurality of light emitting diode strings are driven by the light emitting diode driving voltage supplied from the light emitting diode driver and emits light. The plurality of light emitting diode strings each include a plurality of first LEDs and a plurality of second LEDs connected in series. The light emitting diodes may be configured such that the first and second light emitting diodes having different peak wavelengths are alternately arranged. The first light emitting diode has a peak wavelength of 490 nm, and the second light emitting diode has a peak wavelength of 430 nm.

According to the present invention, when a color temperature level different from the currently set color temperature level is newly input while the LED strings are driven by the LED driving voltage, the input color temperature level is deleted and the newly input color temperature level is set. step; Determining whether the newly set color temperature level is higher than the deleted color temperature level; If the newly set color temperature level is higher than the deleted color temperature level according to the determination result, increasing the level of the LED driving voltage in proportion to the newly set color temperature level to supply the plurality of LED strings; And if the newly set color temperature level is lower than the deleted color temperature level, reducing the level of the LED driving voltage in proportion to the newly set color temperature level and supplying the LED string to the plurality of LED strings.

In the step of supplying by increasing the level of the light emitting diode driving voltage, it is characterized in that to reduce the variable resistance value of the variable resistors connected to both ends of the plurality of light emitting diode strings.

In the reducing and supplying of the level of the LED driving voltage, the variable resistance of the variable resistors connected to both ends of the plurality of LED strings is increased.

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

5 is a configuration diagram of a hybrid backlight unit of a liquid crystal display device according to an exemplary embodiment of the present invention. However, the hybrid backlight unit 300 of the present invention also includes a rectifier 210, a smoother 220, a power factor corrector 230, and a DC / DC converter 240, but the technical features of the present invention are more clearly revealed. 5, the rectifier 210, the smoother 220, the power factor corrector 230, and the DC / DC converter 240 are omitted.

Referring to FIG. 5, the hybrid backlight unit 300 of the present invention includes a light emitting diode driver 250 for converting a DC 400V applied from the DC / DC converter 240 into a light emitting diode driving voltage, and a light emitting diode. A plurality of light emitting diode strings 310 driven by a light emitting diode driving voltage supplied from the driver 250 to emit light, and a plurality of light emitting diode strings 310 to generate a color temperature corresponding to a color temperature level set by a user. The color temperature controller 320 for controlling the color temperature of the plurality of light emitting diode strings 310 by varying the level of the LED driving voltage output from the LED driver 250 under the control of the color temperature controller 320 and the color temperature controller 320. The first driving voltage variable part 330 supplied to one side and the color temperature controller 320 are output from the LED driver 250 under the control of the color temperature controller 320. A second driving voltage variable part 340 is provided to vary the level of the light emitting diode driving voltages and to supply the other side of the plurality of light emitting diode strings 310.

The LED driver 250 converts the DC high voltage (DC 400V) supplied from the DC / DC converter 240 to DC low voltage (DC 35V) and supplies the same to the plurality of LED strings 310, wherein the LED driver The light emitting diode driving voltage output through the first output terminal of 250 is supplied to one end of the plurality of light emitting diode strings 310 through the first driving voltage variable unit 330 and the light emitting diode driver 250 of the light emitting diode driver 250. The LED driving voltage output through the second output terminal is supplied to the other end of the plurality of LED strings 310 through the second driving voltage variable unit 340.

Each of the plurality of light emitting diode strings 310 includes a plurality of first light emitting diodes LED2 and a plurality of second light emitting diodes LED3 connected in series, respectively, as shown in FIG. 6. (LED2) and the second light emitting diode (LED3) are alternately arranged, in particular, the plurality of first light emitting diodes (LED2) has a 490nm peak wavelength, the plurality of second light emitting diodes (LED3) has a 430nm peak wavelength. Have Thus, the present invention is characterized in that the first light emitting diode (LED2) having a relatively long peak wavelength (490nm) and the second light emitting diode (LED3) having a relatively short peak wavelength (430nm) are alternately arranged.

The plurality of light emitting diode strings 310 are driven by the light emitting diode driving voltage which is simultaneously supplied to both ends through the first and second driving voltage variable parts 330 and 340 to emit light. In particular, in the present invention, since the levels of the LED driving voltages are varied by using the first and second driving voltage variable parts 330 and 340, the color temperature of the plurality of LED strings 310 is increased by the first and second driving voltages. The driving voltage is changed according to the level of the light emitting diode driving voltage which is changed by the driving voltage variable parts 330 and 340.

In addition, the present invention alternately arranges the first light emitting diode LED2 having a long peak wavelength (490 nm) and the second light emitting diode LED3 having a short peak wavelength (430 nm), thereby providing a plurality of light emitting diode strings 310. ), The color temperature can be varied more efficiently.

The color temperature controller 320 sets the color temperature level input by the user and displays the color temperature corresponding to the color temperature level so that the variable resistors of the first and second driving voltage variable parts 330 and 340 are changed according to the set color temperature level. Change the value. Here, the user may input the color temperature level by using a remote controller (not shown) that generates a remote control signal, and may also input the color temperature level by pressing a user button (not shown).

The first driving voltage variable part 330 includes a variable resistor VR1 connected between the first output terminal of the LED driver 250 and one end of the plurality of LED strings 310. The variable resistor VR1 is variable by the color temperature controller 320 or by the user. If the product is variable by the consumer while the product is sold to the consumer, the variable resistor value of the variable resistor VR1 is the color temperature controller ( And the variable resistance value of the variable resistor VR1 when the product is changed at the manufacturing stage of the product.

The second driving voltage variable part 340 is composed of a variable resistor VR2 connected between the second output terminal of the LED driver 250 and the other end of the plurality of LED strings 310. The variable resistance VR2 is variable by the color temperature controller 320 or by the user. If the product is variable by the consumer while the product is sold to the consumer, the variable resistance value of the variable resistor VR2 is the color temperature controller ( And the variable resistance value of the variable resistor VR2 when the product is changed at the manufacturing stage of the product. However, the variable resistance values of the variable resistors VR1 and VR2 are equally variable.

More specifically, when the user inputs a color temperature level higher than the current color temperature and sets it to the color temperature controller 320, the color temperature controller 320 decreases the variable resistance values of the variable resistors VR1 and VR2. When the variable resistance values of the variable resistors VR1 and VR2 are reduced in this way, since the level of the LED driving voltage passing through the variable resistors VR1 and VR2 is increased in proportion to the reduced variable resistance value, The color temperature of the diode strings 310 is increased in proportion to the level of the light emitting diode driving voltage.

On the contrary, when the user inputs a color temperature level lower than the current color temperature and sets it to the color temperature controller 320, the color temperature controller 320 increases the variable resistance values of the variable resistors VR1 and VR2. When the variable resistance values of the variable resistors VR1 and VR2 are increased in this way, since the level of the LED driving voltage passing through the variable resistors VR1 and VR2 is reduced in proportion to the increased variable resistance value, a plurality of light emission signals are generated. The color temperature of the diode strings 310 is lowered in proportion to the level of the reduced LED driving voltage.

The operation of the hybrid backlight unit of the present invention having the configuration and function as described above will be described with reference to the flowchart.

7 is a flowchart illustrating a method of driving a hybrid backlight unit of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 7, first, in a state in which the LED strings 310 are driven by the LED driving voltage supplied from the LED driver 250 (S710), the color temperature controller 320 may generate a new color temperature by the user. It is determined whether the level is input (S720).

As a result of determination, if a color temperature level higher than the current color temperature is input, the color temperature controller 320 deletes the current color temperature level and sets a newly input high color temperature level (S730). The variable resistance values of the devices VR1 and VR2 are reduced (S740). Accordingly, since the level of the LED driving voltage passing through the variable resistors VR1 and VR2 is increased in proportion to the decreased variable resistor value, the LED driving voltage with increased color temperature of the plurality of LED strings 310 is increased. It is increased in proportion to the level of (S750).

As a result of determination, if a color temperature level lower than the current color temperature is input, the color temperature controller 320 deletes the current color temperature level and simultaneously sets a newly input low color temperature level (S760). The variable resistance is proportional to the newly set color temperature level. The variable resistance values of the fields VR1 and VR2 are increased (S770). Accordingly, since the level of the LED driving voltage passing through the variable resistors VR1 and VR2 decreases in proportion to the increased variable resistance value, the LED driving voltages with reduced color temperatures of the plurality of LED strings 310 are reduced. It is increased in proportion to the level of (S780).

On the other hand, if a new color temperature level is not input in the determination process (S720), the color temperature controller 320 maintains the variable resistance values of the current variable resistors VR1 and VR2.

As described above, the present invention allows the user to watch a screen having a desired color temperature by allowing the user to arbitrarily adjust the color temperature of the liquid crystal display device generated by the light emitting diodes, and to easily set the color temperature requested by the buyer. Can be.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

Claims (22)

A light emitting diode driver for converting an input voltage into a light emitting diode driving voltage and supplying the light source; A plurality of light emitting diode strings driven by the light emitting diode driving voltages supplied from the light emitting diode drivers to emit light; Color temperature control means for controlling the color temperature of the plurality of light emitting diode strings to generate a color temperature corresponding to a color temperature level set by a user; And And a driving voltage varying means for varying a level of a light emitting diode driving voltage output from the light emitting diode driver and supplying the plurality of light emitting diode strings under the control of the color temperature control means. The driving voltage varying means may include: a first driving voltage varying unit configured to vary a level of a light emitting diode driving voltage output from the light emitting diode driver and to supply one end of the plurality of light emitting diode strings under the control of the color temperature control means; And A hybrid backlight of the liquid crystal display device including a second driving voltage varying part configured to vary a level of a light emitting diode driving voltage output from the light emitting diode driver according to the control of the color temperature control means and to supply the other end of the plurality of light emitting diode strings unit. delete The method of claim 1, The first driving voltage variable part, A first variable resistor connected between the first output terminal of the light emitting diode driver and one end of the plurality of light emitting diode strings Hybrid backlight unit of the liquid crystal display device comprising a. The method of claim 3, wherein The second driving voltage variable part, A second variable resistor connected between the second output terminal of the light emitting diode driver and the other end of the plurality of light emitting diode strings; Hybrid backlight unit of the liquid crystal display device comprising a. 5. The method of claim 4, The color temperature control means decreases the variable resistance values of the first and second variable resistors when the color temperature level higher than the current color temperature is set, and sets the color temperature levels lower than the current color temperature. A hybrid backlight unit of a liquid crystal display device, characterized by increasing the variable resistance value. 6. The method according to any one of claims 1 to 5, The plurality of light emitting diode strings may include a plurality of first light emitting diodes and a plurality of second light emitting diodes, respectively, and the first and second light emitting diodes are alternately arranged. Hybrid backlight unit. The method of claim 6, And the first light emitting diode has a peak wavelength longer than that of the second light emitting diode. The method of claim 7, wherein And said first light emitting diode has a peak wavelength of 490 nm. 9. The method of claim 8, And the second light emitting diode has a peak wavelength of 430 nm. A light emitting diode driver for converting an input voltage into a light emitting diode driving voltage and supplying the input voltage; A plurality of light emitting diode strings driven by the light emitting diode driving voltages supplied from the light emitting diode drivers to emit light; A first variable resistor connected between the first output terminal of the light emitting diode driver and one end of the plurality of light emitting diode strings to vary a level of the light emitting diode driving voltage output from the light emitting diode driver; And A second variable resistor connected between the second output terminal of the light emitting diode driver and the other end of the plurality of light emitting diode strings in order to vary the level of the light emitting diode driving voltage output from the light emitting diode driver; Hybrid backlight unit of the liquid crystal display device comprising a. 11. The method of claim 10, When the variable resistance of the first and second variable resistors is decreased, the color temperature of the plurality of light emitting diode strings is increased. And a color temperature of the plurality of light emitting diode strings is decreased when the variable resistance values of the first and second variable resistors are increased. 11. The method of claim 10, The plurality of light emitting diode strings each include a plurality of first light emitting diodes and a plurality of second light emitting diodes connected in series, and the first and second light emitting diodes are alternately arranged. Hybrid backlight unit. 13. The method of claim 12, And the first light emitting diode has a peak wavelength longer than that of the second light emitting diode. The method of claim 13, And said first light emitting diode has a peak wavelength of 490 nm. 15. The method of claim 14, And the second light emitting diode has a peak wavelength of 430 nm. A light emitting diode driver for converting an input voltage into a light emitting diode driving voltage and supplying the light source; A plurality of light emitting diode strings are driven by the light emitting diode driving voltage supplied from the light emitting diode driver and emits light. Each of the plurality of light emitting diode strings includes a plurality of first light emitting diodes and a plurality of second light emitting diodes connected in series, and the first and second light emitting diodes having different peak wavelengths are alternately disposed. The hybrid light emitting unit of the liquid crystal display device, characterized in that the first light emitting diode has a 490nm peak wavelength. 17. The method of claim 16, And the first light emitting diode has a peak wavelength longer than that of the second light emitting diode. delete The method of claim 17, And the second light emitting diode has a peak wavelength of 430 nm. In the state where the LED strings are driven by the LED driving voltage, when a color temperature level different from the currently set color temperature level is newly input, deleting the currently set color temperature level and setting a newly input color temperature level; Determining whether the newly set color temperature level is higher than the deleted color temperature level; If the newly set color temperature level is higher than the deleted color temperature level according to the determination result, increasing the level of the LED driving voltage in proportion to the newly set color temperature level to supply the plurality of LED strings; And If the newly set color temperature level is lower than the deleted color temperature level, reducing the level of the LED driving voltage in proportion to the newly set color temperature level and supplying the plurality of LED strings to the plurality of LED strings; And the level of the driving voltage is increased or decreased by adjusting the variable resistance of the variable resistors connected to both ends of the plurality of LED strings. 21. The method of claim 20, In the step of supplying by increasing the level of the LED driving voltage, And a variable resistance value of the variable resistors connected to both ends of the plurality of light emitting diode strings. 21. The method of claim 20, In the step of supplying by reducing the level of the LED driving voltage, And a variable resistance value of the variable resistors connected to both ends of the plurality of light emitting diode strings.

Images