KR20080050043A - Display - Google Patents

Abstract

A display device including a direct backlight unit is provided. The display device includes a display panel and a light generator. The display panel includes a first display area and a second display area. The light generating unit includes a first and a second lamp group consisting of a plurality of lamps connected in parallel. The light generation unit provides light having different brightnesses to the first display area and the second display area based on an image signal provided to the display panel from the outside. According to this display device, the brightness can be adjusted for each area of the screen, so that a character image such as a caption displayed at the top and bottom of the screen is more clearly seen, thereby improving the display quality of the display device.

Description

Display device {DISPLAY APPARTUS}

In order to more fully understand the drawings used in the detailed description of the invention, a brief description of each drawing is provided.

1 is a block diagram of a general display device.

2 is a block diagram of a display device according to an exemplary embodiment of the present invention.

3 is a block diagram of the light generator illustrated in FIG. 2.

4 is a diagram illustrating an internal circuit configuration of the first inverter illustrated in FIG. 3.

5 is a view for explaining in detail the connection structure between the inverter unit and the lamp shown in FIG.

The present invention relates to a display device, and more particularly, to a display device including a backlight unit of a direct type.

In general, a liquid crystal display device displays an image by precisely controlling a liquid crystal having a characteristic of changing light transmittance corresponding to an electric field. This liquid crystal display requires light in order to display an image as a non-light emitting element. Therefore, the liquid crystal display device includes a backlight unit in which a liquid crystal panel is disposed on the rear surface to obtain light.

The backlight unit is mainly used a cold cathode fluorescent lamp (CCFL) method, and a surface light source device of the flat-format fluorecent lamp method of assembling the substrate on which the phosphor layer is distributed. In addition, as fluorescent lamps used for backlights, external electrode fluorescent lamps (EEFL) in which both electrodes are disposed outside the tube, and electrodeless fluorescent lamps which do not form electrodes are used. In such a fluorescent lamp, a phosphor is coated on an inner surface of the discharge space, and discharge valences such as xenon, neon, and mercury (hg) are filled in the discharge space.

1 is a block diagram of a general display device.

Referring to FIG. 1, a display device includes a liquid crystal panel 2 having a liquid crystal layer (not shown) formed between two substrates, and a rear surface of the liquid crystal panel 2, the backlight being disposed on the liquid crystal panel 2. It includes a backlight device (4) for supplying. The contrast ratio of the optical image displayed on the display device is affected by the brightness of the backlight and the illuminance of the surrounding environment. It is also affected by the scene characteristics of the displayed optical image.

In particular, a character image such as a caption displayed at the top and bottom of the screen has a value similar to the contrast ratio of the image displayed at the middle of the screen. Therefore, a character image such as a subtitle, which should be highly visible, is not well recognized.

Accordingly, an object of the present invention is to provide a display device capable of increasing the visibility of a text image such as a subtitle.

The display device of the present invention for achieving the above technical problem includes a display panel and a light generating unit. The display panel includes a first display area and a second display area. The second display area is an area adjacent to an upper side and a lower side of the first display area. The light generating unit includes a first and a second lamp group consisting of a plurality of lamps connected in parallel. The light generation unit provides light having different brightnesses to the first display area and the second display area based on an image signal provided to the display panel from the outside. Here, the video signal includes image information and text information, the image information is displayed on the first display area, and the text information is displayed on the second display area.

According to the display device according to the present invention, luminance can be adjusted for each area of the screen, so that a character image such as a caption displayed at the end of the screen is more clearly seen, and as a result, the display quality of the display device is improved.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings. In understanding the drawings, it should be noted that like parts are intended to be represented by the same reference numerals as much as possible. In addition, in the following description, numerous specific details, such as specific processing flows, are described to provide a more general understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the present invention may be practiced without these specific details. Incidentally, detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

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

2 is a block diagram of a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the display device 500 according to an exemplary embodiment of the present invention includes a liquid crystal display panel 100 and a light generator 400. In addition, the display device 500 further includes a driver 220, 250, a signal controller 310, a driving voltage generator 330, a gray voltage generator 340, and an image data analyzer 350.

Specifically, the liquid crystal display panel 100 includes an array substrate (not shown) with a thin film transistor, a color filter substrate (not shown) with a curl pearl filter layer, and a liquid crystal layer provided between the array substrate and the color filter substrate. It includes.

The array substrate includes a plurality of data lines DL1, DL2, ..., DLm, a plurality of gate lines GL1, GL2, ..., GLn, and a plurality of thin film transistors (not shown). The plurality of data lines DL1, DL2,..., DLm extend in the first direction D1, and are arranged side by side at a predetermined distance in the second direction D2. The plurality of gate lines GL1, GL2,..., GLn extend in the second direction D2, and are disposed side by side at a predetermined distance in the first direction D1. That is, the plurality of gate lines GL1, GL2, ..., GLn and the plurality of data lines DL1, DL2, ..., DLm are formed to cross each other insulated.

A plurality of pixel regions defined by the data line and a gate line are formed on the array substrate, and the thin film transistor and the pixel electrode are provided in each of the plurality of pixel regions.

The thin film transistor may include a gate voltage (VON / VOFF) that controls the data line and the gate line to be electrically connected to supply the data voltage and the data voltage corresponding to the image signal to the pixel electrode through the data line. It is input via the line.

Meanwhile, the liquid crystal display panel 100 displays a predetermined image based on an image signal provided from the graphic controller 320 by using light emitted from the light generator 400 described in detail below. The liquid crystal display panel includes a first display area DA1 and a second display area DA2 for displaying the predetermined image.

In the first display area DA1, a predetermined image corresponding to normal image information is displayed. Here, the predetermined image corresponding to the image information refers to a predetermined image including no video, a graphic image, or the like. In the second display area DA2, a predetermined image corresponding to character information is displayed. For example, the predetermined image corresponding to the character information refers to a predetermined image including character information such as a caption displayed on a general screen. Here, the second display area DA2 refers to an area adjacent to an upper side and a lower side of the first display area DA1, respectively.

The drivers 220 and 250 include a data driver 220 and a gate driver 250. The gate driver 220 may also be referred to as a scan driver. The gate driver 220 may be connected to the gate lines GL1, GL2,. A gate signal composed of a combination of (VOFF) is applied to the gate lines GL1, GL2, ..., GLn. The data driver 220 is also referred to as a source driver. The data driver 220 receives a gray voltage from the gray voltage generator 340 and controls the data line data lines DL1, DL2, ... under the control of the signal controller 310. The gray level voltage is selected for each DLm and applied to the data lines DL1, DL2, ..., DLm as data voltages.

The driving voltage generator 330 generates a gate-on voltage VON for turning on the thin film transistor, a gate-off voltage VOFF for turning off the thin film transistor, and a common voltage VCOM applied to the common electrode.

The gray voltage generator 340 generates a plurality of gray scale voltages related to the luminance of the liquid crystal display 1 and supplies them to the data driver 220.

The signal controller 310 generates control signals for controlling operations of the drivers 210 and 220, the driving voltage generator 330, the gray voltage generator 340, and the like. Supply to the generation unit 330.

The image data analyzer 350 receives the image signals R, G, and B from the graphic controller 320, and analyzes shape information of the input image signals R, G, and B. As described above, the shape information of the video signal is classified into image information and character information. The image data analyzer 350 extracts a first luminance value corresponding to the image signal classified as the image information and a second luminance value corresponding to the image signal classified as the character information to the light generator 400. to provide.

Subsequently, the light generator 400 includes an inverter controller 420, an inverter unit 440, and a light generator unit 460. The inverter controller 420 outputs an on / off signal (ON / OFF) and a dimming signal (DIM) based on the first luminance value and the second luminance value from the image data analyzer 350. The inverter unit 440 provides a driving voltage for driving the light generating unit 460 based on the on / off signal ON / OFF and the dimming signal DIM. The light generating unit 460 receives the driving voltage and provides light having different brightnesses to the first display area DA1 and the second display area DA2 of the liquid crystal display panel 100, respectively.

Hereinafter, the light generating unit 400 will be described in more detail with reference to FIG. 3.

3 is a block diagram illustrating an internal configuration of the light generating unit illustrated in FIG. 2 in more detail.

Referring to FIG. 3, the inverter controller 420 outputs a dimming signal DIM and an ON / OFF signal based on first and second luminance values from the image data analyzer 350. do. The dimming signal includes a first dimming signal dim1 and a second dimming signal dim2.

The inverter unit 440 includes a first inverter 440a and a second inverter 440b. The first inverter 440a outputs a first driving voltage Vlamp1 based on the first dimming signal dim1. The second inverter 440b outputs a second driving voltage Vlamp2 based on the second dimming signal dim2.

4 is a diagram illustrating an internal circuit configuration of the first inverter 440a shown in FIG. 3.

Referring to FIG. 4, the first inverter 440a includes a power transistor Q1, a diode D1, an inverting unit 442, a transformer unit 444 formed of a transformer, and a sensing disposed close to an output terminal of the transformer. The unit 446, the detector 447, and the controller 450 are included.

The first inverter 440a converts DC (Vin (DC)) provided from the outside into AC power and provides the same to the first lamp group 460a, that is, a plurality of fluorescent lamps connected in parallel. Preferably, each of the fluorescent lamps is a cold cathode fluorescent lamp.

Here, although the EEFL type lamp having an extra-electrode electrode on both sides of the lamp tube as an example, the EIFL type lamp having an extra-electrode electrode on one side of the lamp tube and an internal electrode on the other side of the lamp tube is applicable. Although not shown, a ballast capacitor may be placed at one end or both ends of the lamps.

The power transistor Q1 is turned on in response to the switching signal SW input from the controller 450 through the gate terminal, and the DC power source Vin (DC) input through the source terminal is inverted through the drain. Switching control is output to 442. The DC power source Vin (DC) is provided from the driving voltage generator 330.

The diode D1 has a cathode terminal connected to the drain terminal of the power transistor Q1, and an anode terminal is grounded to block inrush current flowing back from the inverting unit 442.

The inverting unit 442 includes an inductor L, a resonant capacitor C1, third and fourth resistors R3 and R4, and first and second transistors Q2 and Q3. The second AC power connected to the drain terminal of Q1) and outputted from the power transistor Q1 converts the intermittent DC power into the first AC power, and boosts the converted first AC power to the plurality of lamps LAMP. It is provided to the transformer 444 to provide to each.

In the embodiment of the present invention, the inverting unit 442 is shown to be implemented by a resonant Royer inverter circuit.

Specifically, one end of the inductor L is connected to the drain of the power transistor Q1, and removes an impulse component included in the DC power source Vin (DC) and outputs the other end. Here, the inductor L performs a kind of switching regulating operation of charging energy and averaging the counter electromotive force to the diode D1 during the off period of the power transistor Q1.

The transformer provided in the transformer unit 444 has the first and second windings T1 and T2 constituting the primary winding and the third winding T3 constituting the secondary winding. The AC power inputted through the inductor L of the first winding T1 is transferred to the third winding T3 which is the secondary winding by the electromagnetic induction action to convert the high voltage, and the converted high voltage is converted into the first lamp group ( 460a). Here, the first winding T1 receives a DC power supply from the inductor L through the intermediate tap.

In addition, the second winding T2 selectively turns on either one of the first transistor Q2 and the second transistor Q3 in response to an AC power applied to the first winding T1.

The resonant capacitor C1 is connected in parallel between both ends of the first winding T1 of the transformer to form an LC resonant circuit together with the inductance component of the first winding T1. Here, the second winding T2 connected to the input terminal of the transformer selectively turns on any one of the first transistor Q2 and the second transistor Q3.

The base of the first transistor Q2 is connected to a DC power source input through the third resistor R3, and the collector is connected to one end of the resonant capacitor C1 and the primary winding T1 connected in parallel to the transformer 444. ), The base of the second transistor (Q3) is connected to the DC power input through the fourth resistor (R4), the collector is connected to the other end of the resonant capacitor (C1) and the primary winding (T1) in parallel To drive the transformer, and the emitter is commonly grounded with the emitter of the first transistor Q2.

The sensing unit 446 includes an antenna 446a in which power output through the transformer, that is, the power output through the third winding T3 is disposed close to the wire supplied to the lamp, and senses a voltage flowing through the wire. The supplied voltage is provided to the detection unit 447.

The control unit 450 includes a PWM control unit 452 and a MOSFET driving unit 454, the first dimming signal dim1 provided from the inverter control unit 420 as activated by an on / off signal (ON / OFF), In response to the detection signal 447a provided from the detection unit 447, a switching signal for adjusting the AC power level is provided to the power transistor Q1.

The first dimming signal dim1 is a signal input by a user's operation or the like to adjust the brightness of the lamp and is a digital value having a certain duty ratio. That is, by adjusting this duty ratio, the brightness of the lamp is adjusted. In addition, the detection signal is a signal obtained by comparing the signal sensed from the output terminal of the transformer for supplying the boosted power to the lamp with a predetermined reference signal.

The MOSFET driver 454 amplifies the signal for adjusting the level of the AC power supplied from the PWM controller 452, and provides the amplified level adjusting signal to the power transistor Q1. That is, since the signal output from the PWM controller 452 is a low level signal, the level of the signal is small to be directly applied to the power transistor. Therefore, the MOSFET driver 454 is used to amplify the low level signal.

Referring to FIG. 3 again, the second inverter 440b has the same internal configuration as that of the above-described first inverter 440a, except that the second inverter 440b has a second configuration generated separately from the first dimming signal dim1. The only difference is that the dimming signal dim2 is input.

Subsequently, the light generating unit 460 includes first and second lamp groups 460a and 460b made up of a plurality of lamps. A plurality of lamps included in each of the first and second lamp groups 460a and 460b are connected in parallel.

5 is a view for explaining a connection structure between the inverter and the lamp shown in FIG.

Referring to FIG. 5, each of the first and second lamp groups 460a and 460b may include first common terminals CE1 and CE1 ′ that connect one terminal of the plurality of lamps in common, and the plurality of lamps. And second common terminals CE2 and CE2 'that connect the other terminals in common.

The first common terminal CE1 of the first lamp group 460a is electrically connected to the first terminal E1 of the first inverter 440a to correspond to a high voltage from the first inverter 440a. The driving voltage Vlamp1 is provided. In addition, the second common terminal CE1 ′ of the first lamp group 460a is electrically connected to the second terminal E2 of the first inverter 440a to be connected to a low voltage from the first inverter 440a. The corresponding first driving voltage Vlamp1 is provided.

The first common terminal CE2 of the second lamp group 460b is electrically connected to the third terminal E3 of the second inverter 440b so that the second driving voltage corresponding to the high voltage is increased from the second inverter. Vlamp2) is provided. The second common terminal CE2 ′ of the second lamp group 460b is electrically connected to the fourth terminal of the second inverter 440b to correspond to a low driving voltage from the second inverter. (Vlamp2) is provided.

As such, the first lamp group and the second lamp group receive a driving voltage having a different voltage level from the inverter unit 440. That is, the first lamp group 460a and the second lamp group 460b output light having different brightnesses. In this case, the first lamp group 460a is positioned under the first display area DA1 of the liquid crystal display panel 100, and the second lamp group 460b is located in the second display area (ie, the liquid crystal display panel 100). It is located under the DA2).

Therefore, the first display area DA1 and the second display area DA2 of the liquid crystal display panel 100 display predetermined images at different luminance.

As such, when the screen is divided and luminance is adjusted for each region, the contrast ratio is improved on the entire screen, so that an image displayed in a specific region may be displayed more clearly. For example, the luminance value appearing in the second display area DA2 is set higher than the luminance value appearing in the first display area DA1, and the image appearing in the second display area DA2 is visually recognized more clearly. Therefore, a character image such as a caption mainly displayed at the top and bottom of the screen (corresponding to the second display area DA2) is displayed more clearly, and as a result, the display quality of the display device is improved as a whole.

As such, when the screen is divided and luminance is adjusted for each region, the overall contrast ratio (or also referred to as 'contrast ratio') may be improved to implement clear image quality. Meanwhile, the above-described image data analyzer 350 and the inverter controller 420 may be manufactured by being one-chip or may be designed to be included in the signal controller 310.

According to the present invention as described above, it is possible to adjust the brightness for each area of the screen, so that the text image, such as the caption displayed on the top and bottom of the screen is more clearly seen, resulting in improved display quality of the display device .

As described above, the optimum embodiment has been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not intended to limit the scope of the present invention as defined in the claims or the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (10)

A display panel in which a first display area and a second display area are defined; And A first lamp group corresponding to the first display area and a second lamp group corresponding to the second display area, wherein the first display area and the second lamp group are based on an image signal provided from the outside to the display panel. And a light generator configured to provide light having different brightness to the second display area. The display device of claim 1, wherein each of the first and second lamp groups comprises a plurality of lamps, each of the plurality of lamps being a cold cathode fluorescent lamp. The display device of claim 1, wherein the second display area is an area adjacent to an upper side and a lower side of the first display area. The display apparatus of claim 1, wherein the video signal includes image information and text information. And the image information is displayed on the first display area, and the text information is displayed on the second display area. The method of claim 4, wherein the light generating unit, A controller configured to generate a first dimming signal corresponding to the image information and a second dimming signal corresponding to the text information; And Outputting a first driving voltage to the first lamp group based on the first dimming signal, and generating a second driving voltage having a voltage level different from the first driving voltage based on the second dimming signal; It further includes an inverter unit for output to the lamp group, The first and second driving voltages may be adjusted according to duty ratios of the first and second dimming signals. The display device of claim 5, wherein a duty ratio of the second dimming signal is greater than a duty ratio of the first dimming signal, and a magnitude of the second driving voltage is greater than a magnitude of the first driving voltage. 6. The lamp of claim 5, wherein each of the first and second lamp groups has a first common terminal for commonly connecting one terminals of the plurality of lamps and a second common terminal for commonly connecting the other terminals of the plurality of lamps. And a terminal. The method of claim 7, wherein the power supply unit, First and second terminals electrically connected to the first and second common terminals, respectively, and the first driving voltage corresponding to a high voltage through the first terminal based on the first dimming signal; A first inverter providing the first common terminal of the first lamp group and providing the first driving voltage corresponding to the low voltage to the second common terminal of the second lamp group through the second terminal; And And third and fourth terminals electrically connected to the first and second common terminals, respectively, and supplying the second driving voltage corresponding to the high voltage through the third terminal based on the second dimming signal. And a second inverter configured to provide a first common terminal of the second lamp group, and to provide the second driving voltage corresponding to the low voltage to the second common terminal of the second lamp group through the fourth terminal. Display. The display device of claim 8, wherein the first inverter and the second inverter are electrically separated from each other. The display apparatus of claim 1, wherein the display panel has two substrates facing each other, and a liquid crystal layer provided between the two substrates to control transmission of light provided from the light generator.

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