KR20070080441A - Backlight unit and liquid crystal display apparatus having the same - Google Patents

Abstract

A backlight unit and an LCD(Liquid Crystal Display) having the same are provided to simplify the arrangement structure of control lines connected to the backlight unit, by forming the backlight unit to have a plurality of emission regions arranged in a matrix type so as to control the brightness of the backlight unit according to the emission regions. A plurality of data lines(DL1-DLm) transmit dimming signal. A plurality of gate lines(GL1-GLn) cross the data lines to transmit gate signal. A plurality of switching elements(110) are connected to the data lines and the gate lines, and switched by the gate signal. Voltage controllers(120) are connected to the switching elements. The voltage controllers receive electric power from the outside and output a driving voltage. A plurality of power supply lines(PL1-PLm) supply the electric power the voltage controllers. A plurality of emitting parts(130) are arranged in a matrix type. The emitting parts emit lights by the driving voltage.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY APPARATUS HAVING THE SAME}

1 is a conceptual diagram illustrating a configuration of a backlight unit according to an embodiment of the present invention.

2 is a waveform diagram illustrating a driving signal of a backlight unit according to an exemplary embodiment of the present invention.

3 is a block diagram illustrating a signal controller of a backlight unit according to an exemplary embodiment of the present invention.

4 is a perspective view illustrating a light emitting area of a backlight unit according to an exemplary embodiment of the present invention.

5 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

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

110: switching unit 120: voltage control unit

122: signal storage unit 124: transformer

130: light emitting part DL1-DLm: data line

GL1-GLn: Gate line PL1-PLm: Voltage supply line

200: signal controller 210: luminance signal detector

220: sync signal detector 230: gate signal controller

240: dimming signal control unit

The present invention relates to a backlight unit and a liquid crystal display having the same, and more particularly, to a backlight unit and a liquid crystal display having the same, which can simplify the control wiring of the backlight unit and reduce power consumption.

A liquid crystal display device is a display device that obtains a desired image by applying an intensity-controlled electric field to a liquid crystal material having an anisotropic dielectric constant injected between two substrates, thereby controlling a quantity of light transmitted by the liquid crystal material. In the liquid crystal display device, the magnitude of the signal voltage transmitted to the liquid crystal through the data line is controlled by the gate voltage applied to the gate electrode, and the variable data voltage changes the polarization state of the liquid crystal in stages. It can express various gray levels.

The liquid crystal display requires light in order to display an image as a non-light emitting device. Accordingly, the liquid crystal display device includes a backlight unit disposed on the rear surface of the liquid crystal panel to obtain the light. The backlight unit includes a line light source method using a cold cathode fluorescent lamp (CCFL) and a surface light source using a flat-format fluorescent lamp in which a substrate on which a phosphor layer is distributed is assembled. An expression is being used. In addition, a method using a light emitting diode (LED) is used.

According to the prior art, light is continuously supplied to a portion displaying a dark screen, that is, a portion where a light source is not required. This is one of the causes of increasing the power consumption of the liquid crystal display and shortening the life of the lamp. Therefore, in order to solve this problem, a method of partially adjusting the brightness by dividing the backlight unit into several areas has been studied.

However, currently researched technologies require a separate wiring corresponding to each region in order to adjust the brightness of each region. In this case, the formation of wiring becomes complicated and there is a limit to dividing the backlight unit into more regions.

      SUMMARY OF THE INVENTION The present invention has been made in view of the above, and it is to provide a backlight unit that simplifies the formation of control wiring and reduces power consumption.

      Another object of the present invention is to provide a liquid crystal display device having the above-described backlight unit.

According to an embodiment of the present invention, a backlight unit includes a plurality of data lines, a plurality of gate lines, a plurality of switching units, a plurality of voltage controllers, a plurality of power supply lines, and a plurality of light emitting units. . Each data line carries a dimming signal. Each gate line crosses a plurality of data lines and carries a gate signal. Each switch is connected to a data line and a gate line. It is connected to each switching part and outputs driving voltage by receiving power from outside. Each power supply line supplies power to each voltage control unit. Each light emitting unit is arranged in a matrix form, and emits light by a driving voltage output from each voltage control unit.

      The backlight unit may further include a signal controller configured to provide a dimming signal to each of the data lines and a gate signal to each of the gate lines, and the signal controller may include a luminance signal detector, a sync signal detector, a dimming signal controller, and a gate signal controller. It may include. The luminance signal detector detects a luminance signal from an externally provided image signal. The sync signal detector detects a sync signal from an externally provided video signal. The dimming signal controller generates a dimming signal from the luminance signal and the synchronization signal. The gate signal controller generates a gate signal from the synchronization signal.

The voltage controller may include a signal storage unit and a transformer unit. The signal storage unit may be a capacitor, and the transformer unit may include an OPAMP.

The plurality of power supply lines may be arranged parallel to the data line or the gate line.

Each of the light emitting units may include a light emitting diode, a cold cathode fluorescent lamp, or a flat fluorescent lamp.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a backlight unit and a liquid crystal display panel. The backlight unit includes a plurality of data lines, a plurality of gate lines, a plurality of switching units, a plurality of voltage controllers, a plurality of power supply lines, and a plurality of light emitting units. Each data line carries a dimming signal. Each gate line intersects the plurality of data lines and carries a gate signal. Each switch is connected to a data line and a gate line. It is connected to each switching part and receives the power from the outside to output the driving voltage. Each power supply line supplies power to each voltage control unit. Each light emitting unit is arranged in a matrix form, and emits light by a driving voltage output from each voltage control unit. The liquid crystal display panel includes a liquid crystal layer and controls the transmittance of light provided from the backlight unit.

The backlight unit may further include a signal controller configured to provide a dimming signal to each of the data lines and a gate signal to each of the gate lines, and the signal controller may include a luminance signal detector, a sync signal detector, a dimming signal controller, and a gate signal controller. It may include. The luminance signal detector detects a luminance signal from an externally provided image signal. The sync signal detector detects a sync signal from an externally provided video signal. The dimming signal controller generates a dimming signal from the luminance signal and the synchronization signal. The gate signal controller generates a gate signal from the synchronization signal.

       The voltage controller may include a signal storage unit connected to the switching unit to store a dimming signal, and a transformer unit to convert a voltage of power supplied from the outside based on the signal stored in the signal storage unit.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the scope of the invention to those skilled in the art will fully convey. As described above, when the drawings are described from an observer's point of view, when a part such as a layer, an area, a plate, and the like is located above another part, this includes not only the case where the part is directly above the other part but also another part in the middle. On the contrary, when a part is just above another part, it means that there is no other part in the middle. In each embodiment, descriptions of overlapping components and the same reference numerals may be omitted.

1 is a conceptual diagram illustrating a configuration of a backlight unit according to an embodiment of the present invention. 2 is a waveform diagram illustrating a driving signal of a backlight unit according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the backlight unit includes a plurality of data lines DL1-DLm, a plurality of gate lines GL1-Gln, a switching unit 110, a voltage controller 120, and a plurality of power supply lines PL1-PLm. ), A plurality of light emitters 130, a power supply 140, and a signal controller 200. Each of the data lines DL1 to DLm carries a dimming signal. The dimming signal is output from the signal controller 200 and sequentially transmitted to each data line. Each gate line GL1 -Gln intersects the data lines DL1 -DLm and transfers a gate signal. The gate signal is output from the signal controller, and is sequentially transmitted to each gate line GL1 -Gln. The switching unit 110 is formed in an area defined by a plurality of adjacent data lines and a plurality of adjacent gate lines. The switching unit 110 is connected to a data line and a gate line, and is switched by a gate signal. The switching unit 110 is a thin film transistor (TFT) including a source electrode and a drain electrode.

The voltage controller 120 receives power from the power supply lines PL1 -PLm and outputs a driving voltage based on the dimming signal. The voltage controller 120 includes a signal storage unit 122 and a transformer unit 124. The signal storage unit 122 is connected to the switching unit 110 and stores a dimming signal transferred from each data line to the switching unit 110. The signal storage unit 122 stores the dimming signal, thereby providing a dimming signal to the transformer even after the switch is turned off. As the transformer 124, an OPAMP or a transistor may be used. The signal storage unit 122 may be a capacitor. One end of the signal storage unit 122 is connected to the switching unit, that is, the drain electrode of the thin film transistor, and receives a dimming signal from the switching unit 110.

The light emitting unit 130 receives the driving voltage from the voltage control unit 120 and emits light, and is arranged in a matrix form. The light emitting unit 130 includes at least one light emitting diode. When the light emitting unit 130 includes a plurality of light emitting diodes, each light emitting diode is connected to the voltage controller 120 in parallel and driven simultaneously. In addition to the light emitting diode, a cold cathode fluorescent lamp or a flat fluorescent lamp may be used as the light emitting member of the light emitting part.

The signal controller 200 processes an image signal provided from an image signal source and outputs a dimming signal of each light emitting unit to each data line, and outputs a gate signal corresponding to the gate signal. The dimming signal may have any one of a plurality of preset values. For example, assuming that the maximum luminance of the light emitting unit is 300, a signal corresponding to any one of 100, 200, and 300 or a signal having a value corresponding to non-emission may be output.

Referring to FIGS. 1 and 2, driving of the backlight unit will be described. The gate-on signal output from the signal controller 200 is sequentially transmitted to each transistor along the first gate line GL1, and the gate voltage ( Vg). Each transistor is turned on in turn by the gate-on signal. The dimming signal is transmitted to each data line from the signal controller in accordance with the turn on of the transistor. The dimming signal is provided to the capacitor of the signal storage unit 122 through the drain electrode. The capacitor is stored by the difference ΔV between the voltage Vd of the dimming signal and the reference voltage Vc. In the same way, transistors connected to the first gate line are sequentially turned on, and capacitors connected to each transistor are stored. Next, a gate signal is transferred to the second gate line. By repeating the above steps, each capacitor is stored in turn. The capacitance stored in each capacitor becomes a drive voltage signal that determines the driving voltage supplied to the light emitting portion, that is, determines the luminance of each light emitting portion.

The power supply unit 140 supplies power to each power supply line PL1 -PLm. The power supply unit 140 may convert the DC voltage input from the outside into an AC voltage having a predetermined frequency and amplitude, and provide the converted voltage to each voltage controller 120 through the power supply line. As shown, one power supply line is connected to a plurality of voltage controllers. Therefore, the same voltage is supplied to the plurality of voltage controllers connected to one power supply line. The power supply may be a method of sequentially supplying power in conjunction with a dimming signal or a driving signal of a liquid crystal display panel.

The transformer 124 of the voltage controller 120 transforms the voltage of the power supplied from the power supply line according to the driving voltage signal provided from the signal storage 122. The voltage converted and output may be one of a plurality of preset voltages. In this case, the dimming signal provided to the voltage controller 120 has a value corresponding to one of the preset plurality of voltages. There is no limitation on the number of the plurality of voltage values, but as the number increases, a logic circuit capable of converting the voltage is required.

3 is a block diagram illustrating a schematic configuration of a signal controller of a backlight unit according to an exemplary embodiment of the present invention. 4 is a perspective view illustrating a divided light emitting area of a backlight unit according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the signal controller 200 receives an image signal from an external image signal source. The video signal source is, for example, a signal source for supplying a computer video signal output from a video controller of a computer system or a television video signal output from a television broadcast receiver, the video signal including a video signal and a horizontal / vertical synchronization signal. To supply. The video signal supplied from the video signal source is also input to the driving unit of the liquid crystal display panel to perform driving control of the conventional liquid crystal display panel.

The video signal input from the video signal source has a predetermined number of horizontal scanning lines per frame. For example, in the case of an NTSC system video signal, the number of horizontal scanning lines per frame is 525, and the number of horizontal pixels displayed in one scanning line is 700. Here, the number of horizontal effective scanning lines is 493, and the number of effective horizontal pixels is 658. The image signal supplied to the signal controller 200 is divided into groups corresponding to the light emitting units and processed.

Referring to FIG. 4, the backlight unit has a plurality of light emitting parts arranged in a horizontal and vertical matrix form, and thus the light emitting surface 300 of the backlight unit is divided into light emitting regions 310 corresponding to each light emitting part. . The display surface 400 of the display panel has a plurality of virtually divided image display regions 410 corresponding to each of the light emitting regions. The light emitting parts of the light emitting areas 310 are individually controlled in response to brightness characteristics of each image displayed in the plurality of image display areas of the liquid crystal display panel.

The image display regions 410 correspond one-to-one to the emission region 310 of the backlight unit. The size of the image display area 410 is determined according to the size of the light emitting area. That is, in FIG. 4, the number of pixels included in one image display area is 'a * b (a: number of horizontal pixels, b: number of vertical pixels, and a, b is a positive integer greater than 1)'. . When the number of pixels of one image display area included in the liquid crystal display panel is a * b (a is the number of horizontal pixels, b is the number of vertical pixels, a, b is a positive integer greater than 1), a = (number of horizontal pixels) / (number of horizontal light emitting portions) and b = (number of vertical scanning lines) / (number of water quality emitting portions), respectively.

Referring back to FIG. 3, the signal controller 200 includes a luminance signal detector 210, a sync signal detector 220, a gate signal controller 230, and a dimming signal controller 240. 3 is logically separated for convenience of description but not hardware. For example, the signal controller 200 may be configured as a micom or a digital signal processor (DSP).

The luminance signal detector 210 detects a luminance signal from an externally provided image signal and provides the detected luminance signal to the dimming signal controller 240. The luminance signal detector 210 may be configured as a low pass filter (LPF). The low pass filter removes a high frequency signal in which a color signal component exists and passes only a low frequency signal in which a luminance signal component exists as an image signal is input.

The sync signal detector 220 detects horizontal and vertical sync signals from the image signal, and provides the detected horizontal and vertical sync signals to the dimming signal controller and the gate signal controller.

The gate signal controller 230 generates a gate signal based on the horizontal and vertical synchronization signals detected by the synchronization signal detector.

The dimming signal controller 240 receives the luminance signal from the luminance signal detector 210 and receives the synchronization signal from the synchronization signal detector 220 to generate a dimming signal. The dimming signal controller 240 determines the luminance value of each light emitting unit, that is, the voltage of the dimming signal from the provided luminance signal. For example, the luminance signal of the corresponding light emitting unit may be determined based on an average value of the plurality of luminance signals corresponding to each emission region in one frame. The average value of the detected luminance signals is stored in a register or the like. The average value of the detected luminance signals may not correspond one-to-one with the voltage value of the dimming signal. For example, if the maximum luminance of the light emitting unit is assumed to be 300, the interval is divided into more than 0, less than 100, more than 100, less than 200, more than 200, less than 300, etc., and if the average value of the detected luminance signal is 70, it corresponds to 100 In the case of 120, a dimming signal corresponding to 200 may be generated, and in the case of 230, a dimming signal corresponding to 300 may be generated.

Alternatively, the luminance signal of the corresponding light emitting unit may be determined based on the maximum luminance signal value among the luminance signals corresponding to each emission region instead of the average value of the luminance signals corresponding to each emission region.

The signal detection method for each section as described above will be determined in more detail according to the sequential scanning method, interlaced scanning method, surface division scanning method and the like. However, a more detailed process will be well known to those skilled in the art based on the present invention.

The liquid crystal display according to the exemplary embodiment of the present invention includes a liquid crystal display panel 500 and a backlight unit 600. The liquid crystal display panel 500 includes a lower substrate 510, an upper substrate 520, a liquid crystal layer 530, a printed circuit board 540, and a flexible circuit film 550.

The lower substrate 510 is disposed in a matrix, and includes a plurality of transparent and conductive pixel electrodes, thin film transistors applying a driving voltage to the pixel electrodes, and signal lines for operating the thin film transistors, respectively.

The upper substrate 520 is disposed to face the lower substrate 510. The upper substrate 520 includes a common electrode which is disposed on the front surface and is transparent and conductive.

The liquid crystal layer 530 is interposed between the lower substrate 510 and the upper substrate 520, and is rearranged by an electric field formed between the pixel electrode and the common electrode. The rearranged liquid crystal layer 530 adjusts the light transmittance of light provided from the backlight unit from the outside.

The backlight unit 600 is disposed under the liquid crystal display panel 500 and includes a driving substrate 610, a light emitting diode 620, a storage container 630, and a signal controller.

The driving substrate 610 includes a plurality of data lines, a plurality of gate lines, a plurality of switching units, a plurality of voltage controllers, and a plurality of power supply lines. Each data line carries a dimming signal. Each gate line is arranged to cross the data line and transmits a gate signal. The switching unit is formed in an area defined by a plurality of adjacent data lines and a plurality of adjacent gate lines. The switching unit is connected to the data line and the gate line, and is switched by a gate signal. The voltage controller is connected to each switching unit and receives power from a power supply line to output a driving voltage of the light emitting diode. The power supply line supplies power to each voltage control unit.

The driving substrate 610 may be a printed circuit board (PCB) or a metal coated substrate (MCPCB) coated with a metal having excellent thermal conductivity on the printed circuit board.

The light emitting diodes 620 are disposed in plural on the driving substrate 610, and the entire light emitting diodes are divided into a plurality of light emitting units arranged horizontally and vertically. Each light emitting unit is connected to a voltage controller of the driving substrate 610 and controlled respectively. The light emitting diode 620 may be, for example, a combination of a red light emitting diode, a green light emitting diode, and a blue light emitting diode. Alternatively, the light emitting diode 620 may be a light emitting diode that generates white light.

The storage container 630 defines a storage space by a bottom portion and a side portion extending from an edge of the bottom portion.

The signal controller outputs a dimming signal to a data line of the driving substrate 610 by processing an image signal provided from an external image signal source, and outputs a gate signal to a gate line.

Driving and specific configuration of the backlight unit is a backlight unit according to an embodiment of the present invention described above. In the present exemplary embodiment, the light emitting unit is a light emitting diode. For example, the light emitting unit may be applied to a backlight unit using a cold cathode fluorescent lamp or a flat fluorescent lamp.

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.

As described above in detail, the backlight unit according to the present invention has a matrix structure. Therefore, in controlling the luminance of the backlight unit for each of the plurality of light emitting regions, it is possible to simplify the control wiring connected to each light emitting region. Accordingly, the backlight unit may have more detailed light emitting regions and may reduce overall power consumption by adjusting the luminance of each of the light emitting regions.

Claims (11)

A plurality of data lines carrying a dimming signal; A plurality of gate lines intersecting the plurality of data lines and transferring gate signals; A plurality of switching units connected to the data line and the gate line and switched by a gate signal; A voltage control unit connected to each of the switching units and receiving power from an outside to output a driving voltage; A plurality of power supply lines for supplying power to the voltage controller; And And a plurality of light emitting units arranged in a matrix and emitting light by driving voltages output from the voltage control units. The backlight unit of claim 1, further comprising a signal controller configured to provide a dimming signal to each of the data lines and a gate signal to each of the gate lines.        The method of claim 2, wherein the signal control unit,        A luminance signal detector for detecting a luminance signal from an externally provided image signal; A sync signal detector for detecting a sync signal from the video signal; A dimming signal controller configured to generate a dimming signal from the luminance signal and the synchronization signal; And And a gate signal controller configured to generate a gate signal from the synchronization signal. The voltage controller of claim 1, wherein the voltage controller includes a signal storage unit connected to the switching unit to store a dimming signal, and a transformer unit configured to convert a voltage of power supplied from the outside based on a signal stored in the signal storage unit. The backlight unit characterized by the above-mentioned. The backlight unit of claim 4, wherein the signal storage unit is a capacitor.        The backlight unit of claim 4, wherein the transformer unit comprises an OPAMP. The backlight unit of claim 1, wherein the plurality of power supply lines are arranged in parallel to the data line or the gate line. The backlight unit of claim 1, wherein each of the light emitting units comprises a light emitting diode, a cold cathode fluorescent lamp, or a flat fluorescent lamp. A plurality of data lines transferring a dimming signal, a plurality of gate lines crossing the plurality of data lines and transferring a gate signal, and a plurality of switching units connected to the data lines and the gate lines and switched by a gate signal. A plurality of voltage controllers connected to the unit and outputting a driving voltage by receiving power from an external device, a plurality of power supply lines supplying power to the voltage control units, and a plurality of light emitting diodes arranged in a matrix form by emitting light by the driving voltages output from the respective control units A backlight unit having a light emitting unit; And And a liquid crystal display panel having a liquid crystal layer and controlling a transmittance of light provided from the backlight unit. The method of claim 9, further comprising a signal controller configured to provide a dimming signal to each of the data lines and a gate signal to each of the gate lines.        A luminance signal detector for detecting a luminance signal from the video signal; A sync signal detector for detecting a sync signal from the video signal; A dimming signal controller configured to generate a dimming signal from the luminance signal and the synchronization signal; And And a gate signal controller configured to generate a gate signal from the synchronization signal.        The method of claim 9, wherein the voltage controller includes a signal storage unit connected to the switching unit to store a dimming signal, and a transformer unit to convert a voltage of a power supplied from the outside based on a signal stored in the signal storage unit. A liquid crystal display device.

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