KR20070087277A - Display apparatus - Google Patents

Abstract

A display device is provided to generate a first luminance voltage for light emitting diodes by a driving voltage generating part, thereby removing a circuit such as a clock generating part and a charging pump circuit required for generating the first luminance voltage from a backlight driving part. A display device includes a display panel for displaying images, light emitting diodes(LED1-LED4) for emitting light to the display panel, a control part, a driving voltage generating part, and a backlight driving part(400). The control part generates driving signals for driving the display panel and luminance clock signals corresponding to luminance control data(EN/SET) input from the outside. The driving voltage generating part generates driving voltages for driving the display panel, and a first luminance voltage(VL1) for driving the light emitting diodes in response to the luminance clock signals. The backlight driving part applies the first luminance voltage to an end(OUT1) of each of the light emitting diodes equally, and generates second luminance voltages(VL2) corresponding to the luminance control data, wherein the second luminance voltages are applied to the other ends(OUT2) of the light emitting diodes.

Description

Display device {DISPLAY APPARATUS}

1 is an exploded perspective view illustrating a display device according to an exemplary embodiment of the present invention.

FIG. 2 is a plan view of the display panel illustrated in FIG. 1.

3 is a block diagram of the driving unit shown in FIG. 2.

4 is a block diagram of a backlight driver.

<Description of the symbols for the main parts of the drawings>

410: interface 420: memory unit

430: LED digital / analog converter: light emitting diode

VL1: first luminance voltage VL2: second luminance voltage

EN / SET: luminance control data OUT1: first output terminal

OUT2: second output terminal

The present invention relates to a display device, and more particularly, to a display device for reducing the size of a backlight driver.

In general, the liquid crystal display device is one of the flat panel display device that displays an image by using the light transmittance of the liquid crystal that changes according to the intensity of the electric field, attracting attention because of the light weight, thinness and low power consumption.

The liquid crystal display device includes a display panel including an array substrate and a counter substrate bonded to each other at a predetermined interval, and a liquid crystal panel in which light transmittance is controlled according to an electric field interposed between the array substrate and the counter substrate, and driving signals for driving the liquid crystal. And a driving unit provided to the display panel.

Since the liquid crystal display is a non-light emitting display device, the liquid crystal display includes a backlight assembly having a separate light source for supplying light to the display panel to display an image.

For example, the backlight assembly may include a light source that generates light, a light guide plate for converting light emitted from the light source into a surface light source, and disposed between the light guide plate and the display panel to improve luminance characteristics of light emitted from the light guide plate. Include them.

Representative light sources used in the backlight assembly include a cold cathode fluorescent lamp (CCFL) and an external electrode fluorescent lamp (EEFL). Recently, a light emitting diode (LED) is attracting attention as a light source, and since the light emitting diode is a semiconductor device, it has a long life, a fast lighting speed, and low power consumption.

When the light emitting diode is used as a light source, a backlight driver (for example, a driving chip) that controls the driving of the light source is required. As a result, the backlight driver serves as a disadvantage when a light emitting diode is used as a light source in a small display device.

Accordingly, the technical problem of the present invention is to solve the above disadvantages, and an object of the present invention is to provide a display device for reducing the size of the backlight driver.

A display device according to an exemplary embodiment for realizing the object of the present invention includes a display panel, light emitting diodes, a controller, a driving voltage generator, and a backlight driver. The display panel includes a display area and a peripheral area surrounding the display area, and displays an image by adjusting light transmittance. The light emitting diodes irradiate light to the display panel, and the controller generates driving signals for driving the display panel, and generates a luminance clock signal corresponding to luminance control data provided from an external device. The driving voltage generator generates driving voltages for driving the display panel, and generates a first luminance voltage for driving the light emitting diodes in response to the luminance clock signal. The backlight driver equally provides the first luminance voltage to one end of the light emitting diodes, generates second luminance voltages corresponding to the luminance control data, and provides the second luminance voltages to the other ends of the light emitting diodes, respectively.

According to such a display device, since a first luminance voltage for driving light emitting diodes is generated and provided by a driving voltage generation unit of a driving circuit unit, the backlight driver eliminates a circuit required to generate the first luminance voltage, thereby reducing the size of the backlight driving unit. Can be reduced.

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

1 is an exploded perspective view illustrating a display device according to an exemplary embodiment of the present invention, and FIG. 2 is a plan view of the display panel illustrated in FIG. 1.

1 and 2, a display device according to an exemplary embodiment of the present invention provides light to the display panel 170, the driving circuits 200 and 175 mounted on the display panel 170, and the display panel 170. The backlight assembly 100 is irradiated, and the driving circuits 200 and 175 and the backlight assembly 100 are connected to the printed circuit board 140, the first flexible circuit board 174, and the second flexible circuit board 160. Is electrically connected through.

The display panel 170 includes an array substrate 171 and an opposing substrate 172 (for example, a color filter substrate) facing each other at a predetermined interval, and a liquid crystal layer interposed between the array substrate 171 and the opposing substrate 172. It is divided into an area DA and a peripheral area PA surrounding the display area DA.

In detail, a plurality of pixel parts are formed in the display area DA of the display panel 170 by gate lines GL1 to GLn and data lines DL intersecting each other. Each pixel unit includes a thin film transistor TFT that is a switching element, a liquid crystal capacitor CLC and a storage capacitor CST connected to the thin film transistor TFT. Specifically, the gate electrode and the source electrode of the thin film transistor TFT are electrically connected to the gate line GL and the data line DL, respectively, and the liquid crystal capacitor CLC and the storage capacitor CST are electrically connected to the drain electrode. do.

The driving circuit unit 200 includes the driving unit 200 and the gate driving unit 175, and is mounted in the peripheral area PA of the display panel 170, and the driving unit 200 is the first flexible printed circuit board 174. It is electrically connected to the printed circuit board 140 through.

Specifically, the driving unit 200 is a single chip mounted in the first peripheral area PA1 positioned at one end of the data lines DL1 to DLm, and the data signal received through the first flexible printed circuit board 174. And the display area DA0 is driven based on the synchronization signals. In addition, the driver 200 provides gate control signals and a gate driving voltage for driving the gate driver 175, and generates and provides driving voltages required in the display area DA.

The gate driver 175 is an integrated circuit integrated in the second peripheral area PA2 positioned at one end of the gate lines GL1 to GLn. The gate driver 175 is a turn-on signal of the thin film transistor TFT on the gate lines GL1 to GLn based on the gate control signals and the gate driving voltage provided from the driver 200. The gate signals are output sequentially. The gate control signals include a vertical start signal and a gate clock signal, and the gate driving voltage includes a gate on voltage and a gate off voltage.

The backlight assembly 100 includes a light source 110, a light guide plate 120, and a backlight driver (not shown), and irradiates light to the display panel 170.

Specifically, the light source 110 is composed of one or more light emitting diodes for generating light having a predetermined brightness, in the case of the embodiment includes four light emitting diodes. In the case of the light source, a method of mounting on the second printed circuit board 160 is generally used.

The light guide plate 120 includes an entrance surface formed at one side or both sides and an exit surface formed at an upper side or a lower side thereof. A light source is disposed on the incident surface so that light emitted from the light source is incident through the incident surface and exits through the emission surface. On the other hand, in order to provide light to a plurality of display devices as in a dual clamshell mobile phone, it is also possible to form an emission surface on both the upper side and the lower side so as to emit light.

The backlight driver (not shown) is a driving chip mounted on the printed circuit board 140 and emits light by applying a voltage to the light source. In addition, the voltage provided to the light source is controlled to control the brightness of light emitted from the light source.

Hereinafter, luminance control of a light source according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

3 is a block diagram of the driver shown in FIG. 2, and FIG. 4 is a block diagram of the backlight driver.

1 to 4, the driving unit of the display device according to the exemplary embodiment includes a controller 210, a driving voltage generator 230, a gate controller 220, and a data driver 240.

The controller 210 may externally synchronize the synchronization signals CONT and the data signals DATA including the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, the main clock signal MCLK, and the data enable signal DE. ) And luminance control data (EN / SET). The gate control signal 210a for controlling the gate driver 175, the data control signal 210b for controlling the data driver 240, and the driving voltage generator 230 based on the input synchronization signals CONT. Generates and provides a driving voltage control signal 210d for controlling the control signal, and generates and provides a luminance clock signal 210e based on the luminance control data EN / SET.

Specifically, the gate control signal 210a includes the vertical start signal STV and the gate clock signals CK and CKB, and the data control signal 210b includes the horizontal start signal STH, the load signal LOAD, and the data clock. The signal DCLK is included, and the driving voltage control signal 210d includes a clock signal CLK and an inverted signal POL. In addition, a luminance clock signal 210e having a period and a pulse width corresponding to the luminance control data EN / SET is generated and provided to the driving voltage generator 230.

The driving voltage generator 230 generates driving voltages for driving the display area DA using an externally applied power supply voltage (eg, a battery voltage of about 3V). That is, a gate driving voltage including the gate on voltage VDD and the gate off voltage VSS is generated and provided to the gate controller 220, and a common voltage Vcom is generated to generate a common electrode (eg, the display electrode DA). The gamma voltage VREF is generated and provided to the data driver 240. In addition, the first luminance voltage VL1 is generated in response to the luminance clock signal 210e.

For example, the driving voltage generator 230 includes a charge pump circuit, and the charge pump circuit boosts a power supply voltage input by a switching method. That is, by the on / off operation of the switching element, the accumulation of energy to the inductance and the release of energy are repeated to boost the input voltage (for example, the power supply voltage). The step-up rate of the boosted voltage output by the charge pump circuit is determined by the duty ratio Ton / T defined by the ratio of the switching cycle T of the on / off switching element to the on-operation section Ton of the switching element. Therefore, since the step-up ratio of the first luminance voltage VL1 to the input voltage is determined by the period and the pulse width of the luminance clock signal 210e, the controller generates the luminance clock signal 210e in consideration of this. .

Meanwhile, the first luminance voltage VL1 level generated by the driving voltage generator 230 is boosted to a level 1.5 times or 2 times the input voltage level, and in some cases, 1 times the input voltage level (for example, the input voltage). May be boosted to the same level).

The gate controller 220 provides the gate control signal 210a and the gate driving voltages VDD and VSS to the gate driver 175.

The data driver 240 converts the data signal 210c into a corresponding data voltage based on the gamma voltage VREF and provides the data lines DL1 to DLm.

The backlight driver 400 according to an exemplary embodiment of the present invention receives the luminance control data EN / SET from an external device and receives the first luminance voltage VL1 from the driving voltage generator 230. The luminance control data EN / SET provided to the backlight driver 400 is the same signal as the luminance control data EN / SET provided to the driver 200. That is, the luminance control data EN / SET is provided to the backlight driver 400 and the driver 200.

The provided first luminance voltage VL1 is equally applied to one end of the light emitting diodes LED1 to LED4 configured in parallel through the first output terminal OUT1. That is, one end of the light emitting diodes LED1 to LED4 is connected in parallel to the first output terminal OUT1 to receive the first luminance voltage VL1. The luminance control data EN / SET is converted into the corresponding second luminance voltage VL2 and applied to the other ends of the light emitting diodes LED1 to LED4 through the second output terminals OUT2, respectively.

In detail, the backlight driver 400 may convert the luminance control data EN / SET into a corresponding second luminance voltage VL2, and may include the interface 410, the memory 420, and the digital / analog converter 430. It includes.

The interface 410 receives luminance control data EN / SET from an external device and transfers the luminance control data EN / SET to the memory unit 420.

The memory unit 420 is configured as a memory device for storing luminance data. The memory unit 420 receives luminance control data EN / SET through an interface 410 and outputs corresponding luminance data.

The digital / analog converter 430 converts the luminance data provided from the memory unit 420 into a corresponding analog second luminance voltage VL2 and outputs the converted luminance data. The digital / analog converter 430 includes a number of converters DACs corresponding to the number of light emitting diodes. Here, the second luminance voltage VL2 applied to the other ends of the light emitting diodes LED1 to LED4 is controlled by the output of the converters DACs. That is, the second luminance voltage VL2 provided at the other end of each light emitting diode is controlled by the luminance control data EN / SET, and the second luminance voltage VL2 having the same level as the light emitting diodes LED1 to LED4. May be applied, or the second luminance voltage VL2 of different voltage levels may be applied.

As such, the backlight driver 400 applies the same first luminance voltage VL1 boosted by a predetermined ratio to one end of the light emitting diodes LED1 to LED4, and is applied to the other end of each of the light emitting diodes LED1 to LED4. By adjusting the level of the applied second luminance voltage VL2, the light emitting diodes LED1 to LED4 emit light of the same brightness or emit light of different brightness.

As described above, according to the present invention, the driving voltage generation unit generates and provides the first luminance voltage provided to one end of the light emitting diodes to drive the plurality of light emitting diodes, thereby generating the first luminance voltage in the backlight driver. By eliminating the clock generator and the charge pump circuit used, it is possible to reduce the size of the backlight driver of the chip type.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (5)

A display panel including a display area and a peripheral area surrounding the display area, and configured to display an image by adjusting light transmittance; Light emitting diodes emitting light to the display panel; A controller configured to generate driving signals for driving the display panel and to generate a luminance clock signal corresponding to luminance control data provided from an external device; A driving voltage generator configured to generate driving voltages for driving the display panel and to generate a first luminance voltage for driving the light emitting diodes in response to the luminance clock signal; And a backlight driver configured to equally provide the first luminance voltage to one end of the light emitting diodes and to generate second luminance voltages corresponding to the luminance control data and to provide the second luminance voltages to the other ends of the light emitting diodes, respectively. Device. The display device of claim 1, wherein the second luminance voltages are individually controlled. The display device of claim 2, wherein the first luminance voltage is a voltage obtained by boosting a power supply voltage at a predetermined boost rate. The display device as claimed in claim 3, wherein the boost ratio is one selected from 1, 1.5, and 2 times. The method of claim 1, wherein the backlight driver An interface for receiving and transmitting the luminance control data from an external device; A memory unit for storing luminance data and outputting luminance data corresponding to the luminance control data; And And a digital / analog converter configured to convert the luminance data into a second luminance voltage in an analog form and output the converted luminance data to the light emitting diode.

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