KR20070009294A - Display device - Google Patents

Abstract

A display device is provided to improve brightness uniformity by controlling a switching device corresponding to brightness distribution of light. A light generating unit generates light. A display panel(600) includes a liquid crystal layer controlling transmittance of light according to an arrangement change, a switching device switching arrangement of the liquid crystal layer, and a brightness controller controlling the switching device according to the brightness distribution of light to improve the brightness uniformity of light. The brightness controller includes a control circuit controlling the switching device in order to change a transmission time of the light.

Description

Display {DISPLAY DEVICE}

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

FIG. 2 is a graph illustrating a cross-sectional view and a luminance distribution cut along the line II ′ of FIG. 1.

3 is a block diagram illustrating a display panel in accordance with a signal flow of the display device of FIG. 1.

4 is a plan view illustrating some of the unit pixels of the display panel of FIG. 3.

5A through 5C are waveform diagrams illustrating scan signals and pixel voltages of the display panel of FIG. 4.

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

100: storage container 200: lamp

300: lamp support member 350: sheet support member

400: lamp fixing mold 500: optical member

600: display panel 660: timing controller

670: data driver 675: scan driver

677: luminance distribution memory 680: driving voltage generator

690: display unit 700: top chassis

The present invention relates to a display device, and more particularly, to a display device with improved display quality of an image.

In general, a liquid crystal display (LCD) displays an image by using electrical and optical characteristics of a liquid crystal. The liquid crystal display (LCD) is thinner and lighter than other display devices, and has a low power consumption and a low driving voltage.

The liquid crystal display (LCD) includes a liquid crystal display panel for displaying an image using a light transmittance of liquid crystal and a backlight assembly for providing light to the liquid crystal display panel.

The backlight assembly employed in the liquid crystal display is classified into an edge type backlight assembly and a direct type backlight assembly according to the position of the light source.

The edge type backlight assembly includes one or two light sources and a storage container accommodating the light sources on side surfaces of the transparent light guide plate, and reflects the light generated from the light source through one surface of the light guide plate to the liquid crystal display panel. .

The direct type backlight assembly includes a plurality of lamps disposed below the liquid crystal display panel, a storage container accommodating the lamps, a diffusion plate disposed on the upper surface of the lamps, and a reflecting plate disposed on the lower surface of the lamps. Light emitted from the lamps is reflected by the reflecting plate, diffused by the diffusion plate, and then emitted to the liquid crystal display panel.

Generally, the lamps employed in the direct backlight assembly have a rod shape and are arranged in parallel in the receiving container. Looking at the luminance distribution of the light of the direct type backlight assembly having such an arrangement, the light generated from the lamp is directly emitted to the shortest distance directly to the upper portion of the lamps, while having a high luminance, while the interspace of the lamps The upper portion of the light has a relatively low luminance as the light proceeds obliquely.

As such, as the direct backlight assembly includes the lamps arranged in parallel, a non-uniformity of luminance occurs corresponding to the positions of the lamps, and as a result, display quality of the liquid crystal display (LCD) is deteriorated. There is this.

Accordingly, the technical problem of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a display device in which the display quality of an image is improved by controlling the switching element to improve the uniformity of luminance.

In order to achieve the above object of the present invention, a display device according to an embodiment includes a light generating unit and a display panel. The light generating unit generates light. The display panel includes a liquid crystal layer for controlling the transmittance of the light according to the change of the arrangement, a switching element for changing the arrangement of the liquid crystal layer, and controlling the switching element according to the luminance distribution of the light to improve the luminance uniformity of the light. And a luminance control unit.

Optionally, the luminance controller includes a control circuit for controlling the switching element to change the transmission time of the light. The control circuit controls the switching element to reduce the transmission time of the light corresponding to the region where the brightness of the light is relatively high, and increases the transmission time of the light corresponding to the region where the brightness of the light is relatively low. Control the switching device.

According to such a display device, by controlling the switching element corresponding to the luminance distribution of the light generated by the light generating unit, the luminance uniformity of the display device can be improved to further increase the display quality of the image.

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

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

Referring to FIG. 1, the display device includes a storage container 100, a lamp 200, a lamp support member 300, a sheet support member 350, a lamp fixing mold 400, an optical member 500, a display panel, and the like. Including the top chassis 700, an image is displayed upward.

The storage container 100 includes a bottom part 110 and side parts 120 extending from an edge of the bottom part 110 to define an accommodating space, wherein the accommodating space includes a lamp 200 and a lamp support member ( 300, the sheet support member 350, the lamp fixing mold 400, and the optical member 500 are accommodated.

The lamp 200 generates light. For example, the lamp 200 is a cold cathode fluorescent lamp (CCFL) having a long rod shape along the Y-axis, low heat dissipation, and long life. The lamp 200 is accommodated in the storage container 100, and a plurality of the lamps 200 are arranged in parallel along the X-axis direction. Alternatively, the lamp 200 may be a U-shaped lamp having a U-shaped bar, or an external electrode fluorescent lamp (EEFL) having a rod shape and having an electrode disposed outside thereof.

A plurality of lamp support members 300 are disposed on the bottom part 110 to correspond to the lamps 200. Each lamp support member 300 has a U-shape and supports the lamp 200 having a cylindrical bar shape.

The sheet supporting member 350 has a conical shape and a plurality of the sheet supporting members 350 are disposed on the bottom portion 110. The sheet support member 350 supports the optical member 500 so that the intermediate portion is not sag under load.

The lamp fixing mold 400 is disposed in a pair to face each other in the receiving container 100, and covers both ends of the lamps 200. Fixing grooves 410 are formed in the lamp fixing mold 400 to couple with the lamps 200 having the cylindrical shape. As the fixing grooves 410 are combined with the lamps 200, the lamps 200 are fixed in the storage container 100. In this case, since the electrodes are disposed at both ends of the lamps 200, the lamp fixing molds 400 surround the electrodes.

The optical member 500 is disposed above the lamp 200 to improve optical characteristics of light generated by the lamp 200. At this time, the edge of the optical member 500 is seated on the upper surface of the lamp fixing molds. The optical member 500 includes, for example, a diffusion plate 510 for diffusing light to improve luminance uniformity, and at least one prism sheet 520 for improving front luminance of light through reflection and refraction. .

The display panel 600 is disposed above the optical member 500, and converts light passing through the optical member 500 into image light including information. The display panel 600 includes a first substrate 610, a second substrate 620, a liquid crystal layer 630, a printed circuit board 640, and a flexible printed circuit board 650.

The first substrate 610 includes a plurality of pixel electrodes arranged in a matrix, thin film transistors (TFTs) for applying a driving voltage to the pixel electrodes, and the thin film transistors. Signal lines for operating the respective TFTs.

The second substrate 620 is disposed to face the first substrate 610. The second substrate 620 includes a common electrode which is disposed on the front surface of the second substrate 720 and is transparent and conductive, and color filters disposed to face the pixel electrodes. .

The liquid crystal layer 630 is interposed between the first and second substrates 610 and 620 and rearranged by an electric field formed between the pixel electrode and the common electrode. The rearranged liquid crystal layer 630 adjusts the light transmittance of the light transmitted through the optical member 500, and the light whose light transmittance is adjusted passes through the color filters to display an image.

The printed circuit board 640 includes a driving circuit unit for processing an image signal, and the driving circuit unit converts an image signal input from the outside into a driving signal for controlling the thin film transistor TFT.

The printed circuit board 640 includes a data printed circuit board and a gate printed circuit board. The data printed circuit board is bent by the flexible printed circuit board 650 to be disposed on the side or the back of the receiving container 100, and the gate printed circuit board is bent on the flexible printed circuit board 650 to provide the data printed circuit board. It is disposed on the side or the back of the storage container (100). Meanwhile, the gate printed circuit board may be removed by forming separate signal lines on the first substrate 610 and the flexible printed circuit board 650.

The flexible printed circuit board 650 electrically connects the printed circuit board 640 and the first substrate 610 to receive the driving signal generated from the printed circuit board 640 by the first substrate 610. ) The flexible printed circuit board 650 is, for example, a tape carrier package (TCP) or a chip on film (COF).

The top chassis 700 surrounds an edge of the display panel 600 and is coupled to side portions 120 of the storage container 100 to fix the display panel 600 to an upper portion of the storage container 100. . The top chassis 700 prevents the display panel 600 from being damaged or damaged by brittleness due to external shocks and vibrations, and the display panel 600 is separated from the storage container 100. Prevent it.

The display device may further include a panel fixing member (not shown). The panel supporting member is disposed between the optical member 500 and the display panel 600 to fix the optical member 500 and to support the display panel 600.

FIG. 2 is a graph illustrating a cross-sectional view and a luminance distribution cut along the line II ′ of FIG. 1.

Referring to FIG. 2, the lamp 200 generates light having different luminance according to a position.

In more detail, the luminance distribution of the light is specifically described, light having a relatively low luminance is generated in the a-area a corresponding to the upper portion of the lamp 200, and between the lamp 200 and the lamp 200. Light having a relatively low luminance is generated in the c-region (c) corresponding to, and is approximately intermediate in the b-region (b) located between the a-region (a) and the c-region (c). Light with luminance of is generated.

3 is a block diagram illustrating a display panel in accordance with a signal flow of the display device of FIG. 1.

Referring to FIG. 3, the display panel 600 includes a timing controller 660, a data driver 670, a scan driver 675, a driving voltage generator 680, a display 690, and a luminance controller 677. Include.

The timing controller 660 receives an image signal, which is a digital signal, from an external graphic controller (not shown). The timing controller 660 controls the image signal according to the timing, provides the image data signal DATA2 and the data control signal to the data driver 670, and provides the scan control signal to the scan driver 675. In addition, the driving voltage generator 680 provides a voltage driving signal Pcon.

The image signal provided from the graphic controller includes, for example, a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a main clock MCK, a data enable signal DE, an external data signal DATA1, and the like. There is this.

The vertical synchronization signal Vsync indicates the start or end of each field. The horizontal synchronization signal Hsync indicates the start or end of a row line in the display panel 500. The main clock MCK is a signal for synchronizing the external data signal DATA1. The data enable signal DE defines an effective range of the external data signal DATA1 between the horizontal synchronization signal Hsync and the horizontal synchronization signal Hsync. The external data signal DATA1 includes RGB image information for displaying an image.

The data driver 670 receives the image data signal DATA2 and the data control signal generated by the timing controller 660, and converts the image data signal DATA2 into the data driving signal by the data control signal. Is converted and applied to the data lines D1, D2, ..., D2m of the display unit 690 (where m is a natural number).

The data control signal includes a data start signal STH for notifying the start of the image data signal DATA2, a data load signal Load for notifying the output of the data driving signal after the transmission of the image data signal DATA2 is completed. And a data synchronizing signal DOT for synchronizing the image data signal DATA2.

The scan driver 675 receives the scan control signal generated by the timing controller 660 and is controlled by the scan control signal to scan lines G1, G2,..., Gn of the display unit 690. The scan driving signal is sequentially applied. (Where n is a natural number.) The scan control signal is used to synchronize the scan driving signal and the scan driving signal indicating the start of the output of the scan driving signal. It includes a scan clock GCK. In this case, the scan driver 675 receives an on / off reference voltage Von / Voff that provides a reference voltage of the scan driving signal from the driving voltage generator 680.

The driving voltage generator 680 is driven by receiving power Vcc from an external source, and is controlled by receiving the voltage driving signal Pcon from the timing controller 660 to control the scan driver 675 and the display unit ( 690 outputs a driving voltage necessary for driving.

For example, the on / off reference voltage Von / Voff applied to the scan driver 675, the common voltage Vcom applied to the common electrode formed on the display unit 690, and the display unit include the driving voltage. And a storage reference voltage Vst applied to the reference voltage line formed at 690.

The display unit 690 may include the first substrate 610 having a plurality of switching elements, a second substrate 620 disposed to face the first substrate 610, and having a plurality of color filters, and the first substrate 610. And a liquid crystal layer 630 interposed between the second substrates 610 and 620. The switching elements are, for example, thin film transistors.

A plurality of data lines D1, D2,..., D2m are disposed in parallel along the first direction on the first substrate 610, and a plurality of scan lines G1, G2,. It is disposed in parallel along a second direction perpendicular to the first direction. The data lines D1, D2, ..., D2m and the scan lines G1, G2, ..., Gn cross each other to define pixel regions, and unit pixels are formed in each of the pixel regions. .

Each unit pixel includes a thin film transistor, a liquid crystal capacitor Clc, and a storage capacitor Cst, which are switching elements. Each thin film transistor includes a gate electrode, a source electrode and a drain electrode. The gate electrode is connected to the scan lines G1, G2, ..., Gn, the source electrode is connected to the data lines D1, D2, ..., D2m, and the drain electrode is the liquid crystal. It is connected to the pixel electrode which is the first electrode of the capacitor Clc.

The second substrate 620 includes color filters including color pixels corresponding to each unit pixel, and a common electrode applied with the common voltage Vcom and a second electrode of the liquid crystal capacitor Clc.

The liquid crystal capacitor Clc is defined by the pixel electrode connected to the drain electrode and the common electrode applying the common voltage Vcom. In addition, the storage capacitor Cst is defined by a reference voltage line applying the storage reference voltage Vst and the pixel electrode.

The luminance controller 677 generates a luminance control signal Gcon and applies it to the scan driver 675. The scan driver 675 is controlled by the luminance control signal Gcon applied to change the characteristics of the scan driving signal.

The luminance controller 677 includes a luminance distribution memory (not shown) and a scan control circuit (not shown).

The luminance distribution memory stores information on the luminance distribution of the light generated by the lamp 200. The luminance distribution memory controls the scan control circuit based on the information stored in the luminance distribution memory.

The scan control circuit changes and outputs the scan driving signal based on the information stored in the luminance distribution memory. For example, the scan control circuit is applied to the scan driver 675 to change the time of the high level of the scan driving signal.

Specifically, the scan control circuit changes the time of the high level of the scan driving signal relatively long corresponding to the a-region a with the low luminance, and the c-region c with the high luminance. Corresponding to), the time of the high level of the scan driving signal is changed relatively short.

4 is a plan view illustrating some of the unit pixels of the display panel of FIG. 3.

Referring to FIG. 4, for example, three scan lines are arranged along the X-axis and four data lines are disposed along the Y-axis in the unit pixel of the display panel 600. The scan lines include a first scan line Ga, a second scan line Gb, and a third scan line Gc, and the data lines include a first data line Do and a second data line Dp. ), A third data line Pq and a fourth data line Pr.

The pixel electrodes driven by the first scan line Ga and the data lines are defined as a first pixel electrode Pa, and are driven by the second scan line Ga and the data lines. The pixel electrodes are defined as a second pixel electrode Pb, and the pixel electrodes driven by the third scan line Gc and the data lines are defined as a third pixel electrode Pc. In this case, the first pixel electrode Pa is disposed corresponding to the a-region a of the lamp 200, and the second pixel electrode Pb is the b-region b of the lamp 200. The third pixel electrode Pc is disposed corresponding to the c-region c of the lamp 200.

5A through 5C are waveform diagrams illustrating scan signals and pixel voltages of the display panel of FIG. 4. Specifically, FIG. 5A is a waveform diagram showing a scan signal and a pixel voltage for a high luminance distribution, FIG. 5B is a waveform diagram showing a scan signal and a pixel voltage for an intermediate luminance distribution, and FIG. 5C is a scan for a high luminance distribution. A waveform diagram showing signals and pixel voltages.

3 and 5A, the luminance controller 677 generates a first luminance control signal corresponding to an a-region a having a relatively low luminance of the light. The first luminance control signal is applied to the scan driver 675 to output a first scan driving signal having a first high level time t1.

The first scan driving signal is applied to the gate electrode along the first scan line Ga to electrically connect the source electrode and the drain electrode during the first high level time t1. As a result, charge is charged in the first pixel electrode Pa, which is electrically connected to the drain electrode, and an electric field is formed between the first pixel electrode Pa and the common electrode. During t1), light is transmitted through the liquid crystal layer 630.

3 and 5B, the luminance controller 677 generates a second luminance control signal corresponding to the b-region b in which the luminance of the light is relatively intermediate. The second luminance control signal is applied to the scan driver 675 to output a second scan driving signal having a second high level time t2 less than the first high level time t1.

The second scan driving signal is applied to the gate electrode along the second scan line Gb to electrically connect the source electrode and the drain electrode during the second high level time t2. As a result, charge is charged in the second pixel electrode Pb electrically connected to the drain electrode, and an electric field is formed between the second pixel electrode Pb and the common electrode, and thus the second high level time ( During t2), light is transmitted through the liquid crystal layer 630.

3 and 5C, the luminance controller 677 generates a third luminance control signal corresponding to the c-region c having a relatively high luminance of the light. The third luminance control signal is applied to the scan driver 675 to output a third scan driving signal having a third high level time t3 smaller than the second high level time t2.

The third scan driving signal is applied to the gate electrode along the third scan line Gc to electrically connect the source electrode and the drain electrode during the third high level time t3. As a result, a charge is charged in the third pixel electrode Pc electrically connected to the drain electrode, and an electric field is formed between the third pixel electrode Pc and the common electrode, so that the third high level time ( During t3), light is transmitted through the liquid crystal layer 630.

As such, the relatively high luminance reduces the transmission time of the light to control the switching element to lower the luminance relatively, while the relatively low luminance increases the transmission time of the light to increase the luminance relatively. By controlling the switching element, the display device can display an image having improved luminance uniformity of light.

In the drawing, the pixel electrode is charged when the scan driving signal rises, and the pixel electrode is discharged when the scan driving signal falls. That is, the pixel electrode is charged and discharged by the scan driving signal.

Alternatively, the pixel electrode may be charged by the scan driving signal and discharged by a separate discharge signal. That is, the discharge signal is applied to the switching element separately from the scan driving signal, and thus the pixel electrode transmits light through the liquid crystal layer 630 during the time between the scan driving signal and the discharge signal. As such, as the transmission time of the light is changed by the difference in the application time between the scan driving signal and the discharge signal, the display device may display an image having a more improved brightness uniformity.

As described above, according to the present invention, in response to the luminance distribution of the light generated in the light generating unit, the transmission time of the light is reduced to a place having a relatively high brightness, and the light is transmitted to a place having a relatively low brightness. By controlling the switching element to increase the time, the display device can display an image with more improved luminance uniformity.

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 (6)

A light generating unit for generating light; And A liquid crystal layer for controlling the transmittance of the light in accordance with the change of arrangement, a switching element for changing the arrangement of the liquid crystal layer, and a brightness control unit for controlling the switching element in accordance with the luminance distribution of the light to improve the luminance uniformity of the light And a display panel having a display panel. The display device of claim 1, wherein the luminance controller comprises a control circuit that controls the switching element to change a transmission time of the light. The method of claim 2, wherein the control circuit Controlling the switching element to reduce the transmission time of the light in response to a region where the brightness of the light is relatively high; And the switching element is controlled to increase the transmission time of the light in response to a region where the brightness of the light is relatively low. The display device of claim 1, wherein the display panel further comprises a data line transmitting a data signal to the switching element, and a scan line crossing the data line to transmit a scan signal to the switching element. And the brightness control unit includes a scan control circuit for changing the scan signal to control the switching element. The method of claim 4, wherein the scan control circuit Controlling the switching element to reduce an application time of the scan signal corresponding to a region where the brightness of the light is relatively high; And controlling the switching element to increase an application time of the scan signal in response to a region where the brightness of light is relatively low. The display apparatus of claim 1, wherein the luminance controller comprises a luminance distribution memory configured to store information on the luminance distribution of the light.

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