KR20060041025A - Display device and backlight apparatus - Google Patents

Abstract

The present invention relates to a backlight device including a plurality of light sources connected in parallel. Each of the plurality of light sources includes a high voltage electrode terminal connected to a high voltage and a low voltage electrode terminal connected to a ground. At this time, the high voltage electrode stage and the low pressure electrode stage are alternately arranged in the column direction. The backlight device also includes an inverter unit for applying an alternating voltage to the plurality of light sources to blink the light source, and the inverter unit includes a plurality of transformers connected to the high voltage electrode side of the light source. For this reason, since it is arrange | positioned at the high voltage | voltage electrode terminal and the low voltage electrode terminal in one column, the average amount of current which leaks in the high voltage | voltage electrode terminal and the voltage electrode terminal of both rows is the same, respectively. Therefore, the average brightness of the light irradiated from the light source is kept uniform regardless of the position of the light source.

LCD, LCD, Backlight, Light Source, CCFL, Drift

Description

Display and Backlight Device {DISPLAY DEVICE AND BACKLIGHT APPARATUS}

1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

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

3 is an equivalent circuit diagram of one pixel of a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a connection state of a transformer of a transformer unit and a lamp of a light source unit according to an exemplary embodiment of the present invention.

The present invention relates to a display device and a backlight device.

Display devices used in monitors and TVs of computers include light emitting diodes (LEDs), electroluminescence (EL), vacuum fluorescent displays (VFDs), and electroluminescent devices (fields). emission display (FED), plasma display panel (PDP), and the like, a liquid crystal display (LCD) that does not emit light by itself and requires a light source.                         

A general liquid crystal display device includes two display panels provided with a field generating electrode and a liquid crystal layer having dielectric anisotropy interposed therebetween. A voltage is applied to the field generating electrode to generate an electric field in the liquid crystal layer, and the voltage is changed to adjust the intensity of the electric field, thereby adjusting the transmittance of light passing through the liquid crystal layer to obtain a desired image.

In this case, the light may be a separate artificial light source or natural light.

A light source for a liquid crystal display, that is, a backlight device, uses a plurality of fluorescent lamps such as a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL) as a light source and includes an inverter for driving the lamp. . The inverter converts the DC power input into AC power according to the brightness control voltage input from the outside and applies it to the lamp to light it, adjusts the brightness of the lamp, senses the voltage related to the current flowing through the lamp and based on the detected voltage. To control the voltage applied to the lamp.

For such lamp control, in the case of CCFL, a high voltage is applied to a hot electrode of a lamp by using a separate transformer for each lamp, and a low voltage (cold) electrode is connected to ground with a current sensing resistor in common.

In general, since a leakage current is generated when a high voltage is applied rather than when a low voltage is applied, a difference between the leakage current generated at the high voltage electrode side and the leakage current generated at the low voltage electrode side is applied to the CCFL. Severe occurrences cause large temperature differences. Therefore, the operating state of the lamp is unstable, resulting in an unbalance of brightness, resulting in deterioration of image quality.

To reduce this difference in leakage current, transformers can be installed across the lamp, but this is costly.

Therefore, the technical problem to be achieved by the present invention is to compensate for the difference in luminance between the both ends of the light source.

Another technical problem to be achieved by the present invention is to maintain the brightness of the light source unit uniformly without increasing the manufacturing cost.

According to an aspect of the present invention, a backlight device includes a plurality of light sources arranged in parallel and having first and second terminals, and applying an alternating voltage to the plurality of light sources to blink the light sources. And an inverter unit, wherein the first and second terminals are alternately arranged in the column direction.

The inverter unit receives a DC voltage from the outside and outputs an AC voltage, a transformer unit for changing the AC voltage from the switching unit and applying it to the light source, and connected to the switching unit, thereby operating the switching unit. It is preferable to include a switching control unit for controlling.

The transformer may include a plurality of transformers connected to the first terminals of the respective light sources.

The first terminal may be a high voltage electrode terminal, and the second terminal may be a low voltage electrode terminal.                     

In the above feature, the plurality of light sources may be CCFLs.

According to another aspect of the present invention, a display device includes a plurality of pixels, at least two lamps supplying light to the pixels based on a blinking control signal, and applying the blinking control signal using a direct current voltage from the outside. An inverter unit for blinking a light source, wherein the lamp is provided with a high voltage electrode end and a low pressure electrode end, and the high voltage electrode end and the low pressure electrode end are alternately arranged in the column direction.

The inverter unit receives a DC voltage from the outside and outputs it as an AC voltage, a transformer unit for changing the AC voltage from the switching unit and applying it to the lamp, and connected to the switching unit to control the operation of the switching unit. And a switching control unit, and the transformer unit may include at least two transformers connected to the high voltage electrode ends of the lamps.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a portion of a layer, film, region, plate, etc. is said to be "on top" of another part, this includes not only when the other part is "right on" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.                     

A liquid crystal display, which is an embodiment of a display device according to an embodiment of the present invention, will now be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view of a liquid crystal display according to an embodiment of the present invention, FIG. 2 is a block diagram of a liquid crystal display according to an embodiment of the present invention, and FIG. 3 is a liquid crystal according to an embodiment of the present invention. It is an equivalent circuit diagram of one pixel of a display device. 4 is a diagram illustrating a connection state of a transformer of a transformer unit and a lamp of a light source unit according to an exemplary embodiment of the present invention.

As shown in FIG. 1, an LCD according to an exemplary embodiment of the present invention may include a liquid crystal module 350 including a display unit 330 and a backlight unit 900, and an upper portion and a lower portion accommodating the liquid crystal module 350. Chassis 361 and 362 and mold frame 366.

The display unit 330 includes a liquid crystal panel assembly 300, a plurality of gate carrier package (TCP) 410 and data TCP 510 attached thereto, and a gate printed circuit board attached to the corresponding TCPs 410 and 510. A printed circuit board (PCB) 450 and a data PCB 550.

The liquid crystal panel assembly 300 includes a lower panel 100, an upper panel 200, and a liquid crystal layer 3 interposed therebetween.

The lower panel 100 includes a plurality of display signal lines G ₁ -G _n , D ₁ -D _m , and the lower and upper panel 100, 200 includes display signal lines G ₁ -G _n , D ₁ -D _m ) and includes a plurality of pixels arranged in a substantially matrix form.

The display signal lines G ₁ -G _n and D ₁ -D _m are a plurality of gate lines G ₁ -G _n for transmitting a gate signal (also called a “scan signal”) and a data line D for transmitting a data signal. ₁ -D _m ). The gate lines G ₁ -G _n extend substantially in the row direction and are substantially parallel to each other, and the data lines D ₁ -D _m extend substantially in the column direction and are substantially parallel to each other.

Each pixel includes a switching element Q connected to a display signal line G ₁ -G _n , D ₁ -D _m , and a liquid crystal capacitor C _LC and a storage capacitor C _ST connected thereto. It includes. The holding capacitor C _ST can be omitted as necessary.

The switching element Q, such as a thin film transistor, is provided in the lower panel 100, and the control terminal and the input terminal are three-terminal elements, respectively, with gate lines G ₁ -G _n and data lines D ₁ -D _m . The output terminal is connected to a liquid crystal capacitor (C _LC ) and a holding capacitor (C _ST ).

The liquid crystal capacitor C _LC has two terminals, the pixel electrode 190 of the lower panel 100 and the common electrode 270 of the upper panel 200, and the liquid crystal layer 3 between the two electrodes 190 and 270. It functions as a dielectric. The pixel electrode 190 is connected to the switching element Q, and the common electrode 270 is formed on the front surface of the upper panel 200 and receives a common voltage V _com . Unlike in FIG. 3, the common electrode 270 may be provided in the lower panel 100. In this case, at least one of the two electrodes 190 and 270 may be linear or rod-shaped.

The storage capacitor C _ST , which serves as an auxiliary part of the liquid crystal capacitor C _LC , is formed by overlapping a separate signal line (not shown) and the pixel electrode 190 provided on the lower panel 100 with an insulator interposed therebetween. A predetermined voltage such as the common voltage V _com is applied to this separate signal line. However, the storage capacitor C _ST may be formed such that the pixel electrode 190 overlaps the front end gate line directly above the insulator.

On the other hand, to implement color display, each pixel uniquely displays one of the three primary colors (spatial division) or each pixel alternately displays the three primary colors over time (time division) so that the desired color can be selected by the spatial and temporal sum of these three primary colors. To be recognized. 3 illustrates an example of spatial division, in which each pixel includes a red, green, or blue color filter 230 in a region corresponding to the pixel electrode 190. Unlike FIG. 3, the color filter 230 may be formed above or below the pixel electrode 190 of the lower panel 100.

A polarizer (not shown) for polarizing light is attached to an outer surface of at least one of the two display panels 100 and 200 of the liquid crystal panel assembly 300.

As shown in FIG. 1, the gate TCP 410 is attached to one edge of the lower panel 100 of the liquid crystal panel assembly 300, and a gate driving integrated circuit constituting the gate driver 400 is formed on the chip. Equipped with. The data TCP 510 is attached to the other edge of the lower panel 100 of the liquid crystal panel assembly 300, and a data driver integrated circuit constituting the data driver 500 is mounted in the form of a chip. The gate driver 400 and the data driver 500 may include the gate lines G ₁ -G _n and the data lines of the liquid crystal panel assembly 300 through signal lines (not shown) formed in the TCPs 410 and 510. D ₁ -D _m ) are each electrically connected.

The gate driver 400 applies a gate signal formed of a combination of the gate on voltage V _on and the gate off voltage V _off to the gate lines G ₁ -G _n , and the data driver 500 applies the data voltage. It is applied to the data lines D ₁ -D _m .

Alternatively, the integrated circuit chip that forms the gate driver 400 and the data driver 500 may be integrated on the display panel without using TCP (chip on glass, COG mounting method), and the gate driver 400 or the data driver 500 may be formed directly on the liquid crystal panel assembly 300 together with the switching element Q and the display signal lines G ₁ -G _n and D ₁ -D _m .

The gate PCB 450 is attached to the TCP 410 in the longitudinal direction in parallel to the lower panel 100, and a plurality of signal lines (not shown), electronic components, and the like for transmitting signals are formed thereon.

The data PCB 550 is attached to the TCP 510 in the longitudinal direction in parallel to the lower panel 100, and a plurality of signal lines (not shown), electronic components, and the like for transmitting signals are formed thereon.

The gray voltage generator 800 generates two sets of gray voltages related to the transmittance of the pixel and provides them to the data driver 500 as data voltages. One of the two sets has a positive value for the common voltage (V _com ) and the other set has a negative value.

As shown in FIGS. 1 and 4, the backlight unit 900 is fixed to the lower chassis 362, and is disposed on the lower chassis 362 at a predetermined distance from the light source unit 960, the assembly 300, and the light source unit. Located between the 960 and a plurality of optical instruments 910 for processing light from the light source unit 960, and an inverter unit 920 for controlling the light source unit 960.

The light source unit 960 includes a plurality of lamps LP1, LP2, LP3, ... such as fluorescent lamps, and lamps LP1, LP2, LP3, .. Lamp holder 365 for holding and holding, lamp holder 364 for preventing damage caused by sag of lamps LP1, LP2, LP3, ..., and lamps And a reflective sheet 363 reflecting light emitted from LP1, LP2, LP3, ... toward the liquid crystal panel assembly 300.

The plurality of lamps LP1, LP2, LP3,... Are arranged in parallel and include a high voltage electrode terminal connected to a high voltage and a low voltage electrode terminal connected to the ground. The high voltage electrode stage and the low voltage electrode stage are alternately arranged in the column direction.

In this embodiment, the lamps LP1, LP2, LP3, ... use CCFLs but may use other kinds of light sources. The number of lamps LP1, LP2, LP3,... Of the light source unit 960 shown in FIGS. 1 and 4 may be added or subtracted as necessary.

The inverter unit 920 is connected to the inverter control unit 921, the inverter control unit 921, the switching unit 922, the transformer unit 923 connected to the switching unit 922 and the light source unit 960, and the light source unit 960. And a current detector 924 connected to the inverter controller 921.

As shown in FIG. 4, the transformer 923 includes a plurality of transformers T1, T2, T3,..., Connected to the lamps LP1, LP2, LP3,... These transformers T1, T2, T3, ... are connected to the high voltage electrode ends of the corresponding lamps LP1, LP2, LP3, ....

Therefore, the mounting position of the transformers T1, T2, T3, ... also depends on the position of the high voltage electrode terminals of the corresponding lamps LP1, LP2, LP3, ..., and the lamps LP1, LP2, LP3 in the column direction. , ...) alternately on the left or right side. In Fig. 4, the transformers T1, T3, ... connected to the odd-numbered lamps LP1, LP3, ... are mounted on the left side of the lamps LP1, LP3, ..., and the even-numbered lamps LP2. Transformers (T2, T4, ...) connected to, LP4, ... are mounted on the right side of the lamps (LP2, LP4, ...), but these lamps (LP1, LP2, LP3, ...) Alternatively, the mounting position or the connection position of the transformers T1, T2, T3, ... may be changed.

The inverter unit 920 may be provided in a separately mounted inverter PCB (not shown) or may be provided in the gate PCB 450 or the data PCB 550.

In FIG. 1, the optical apparatus 910 is positioned between the assembly 300 and the light source unit 960 and includes a diffuser plate 902 and a plurality of optical sheets that guide and diffuse light from the light source unit 960 to the assembly 300. 901).

As shown in FIG. 1, a method in which the lamps LP1, LP2, LP3,... Of the light source unit 960 are disposed below the lower panel 100 is called a direct type, and the lamps LP1, LP2. , LP3, ...) is disposed at the lower edge of the liquid crystal panel assembly 300 and a light guide is disposed in place of the diffuser plate 902, which is called an edge type.

Although not shown in FIG. 1, an upper case and a lower case are positioned at an upper portion of the upper chassis 361 and a lower portion of the lower chassis 362, respectively, to form a liquid crystal display device by combining them.

The signal controller 600 controls operations of the gate driver 400 and the data driver 500.

The display operation of such a liquid crystal display device will now be described in detail.

The signal controller 600 is configured to control the input image signals R, G, and B and their display from an external graphic controller (not shown), for example, a vertical synchronization signal Vsync and a horizontal synchronization signal ( Hsync, main clock MCLK, and data enable signal DE are provided. The signal controller 600 properly processes the image signals R, G, and B according to the operating conditions of the liquid crystal panel assembly 300 based on the input image signals R, G, and B and the input control signal, and controls the gate control signal. After generating the CONT1 and the data control signal CONT2, the gate control signal CONT1 is sent to the gate driver 400, and the data control signal CONT2 and the processed image signal DAT are transmitted to the data driver 500. Export to

The gate control signal (CONT1) is such as at least one clock signal for controlling the output time and the output voltage of the start scan to indicate the start of output of a gate-on voltage (V _on) signal (STV), a gate-on voltage (V _on) Include.

The data control signal CONT2 includes a horizontal synchronous start signal STH indicating the start of transmission of the image data DAT, a load signal LOAD for applying a data voltage to the data lines D ₁ -D _m , and a common voltage ( An inversion signal RVS and a data clock signal HCLK for inverting the polarity of the data voltage with respect to V _com (hereinafter, referred to as the polarity of the data voltage by reducing the polarity of the data voltage with respect to the common voltage).

The data driver 500 sequentially receives and shifts the image data DAT for one row of pixels according to the data control signal CONT2 from the signal controller 600, and the gray voltage from the gray voltage generator 800. The grayscale voltage corresponding to each image data DAT is selected to convert the image data DAT into a corresponding data voltage, and then apply the grayscale voltage to the corresponding data lines D ₁ -D _m .

The gate driver 400 applies the gate-on voltage V _on to the gate lines G ₁ -G _n in response to the gate control signal CONT1 from the signal controller 600, thereby applying the gate lines G ₁ -G _n. ) Turns on the switching element Q connected thereto, so that the data voltage applied to the data lines D ₁ -D _m is applied to the corresponding pixel through the turned-on switching element Q.

The difference between the data voltage applied to the pixel and the common voltage V _com is shown as the charging voltage of the liquid crystal capacitor C _LC , that is, the pixel voltage. The liquid crystal molecules vary in arrangement depending on the magnitude of the pixel voltage.

The inverter unit 920 converts and transforms a DC voltage applied from the outside into an AC voltage and applies the voltage to the light source unit 960. The light source unit 960 blinks according to the voltage, and the brightness of the light source unit 960 is controlled.

The operation of the inverter unit 920 will be described in more detail as follows.

First, the operation of the switching unit 922 is determined according to a signal from the inverter control unit 921, and converts a direct current (DC) voltage from the outside into an alternating current (AC) voltage of a corresponding frequency to convert each of the transformers 923. Applied to transformers T1, T2, T3, ..

The transformers T1, T2, T3, .. of the transformer 923 boost the AC voltage applied from the switching unit 922 to a high voltage based on the turns ratio, so that the corresponding lamps LP1, LP2, LP3, ...), each of the lamps LP1, LP2, LP3, ... of the light source unit 960 is turned on.

When the light source unit 960 is turned on, the current detector 924 applies a voltage proportional to the current flowing through the lamp of the light source unit 960 to the inverter controller 921 using a current sensing resistor (not shown). .

Based on the signal from the current sensing unit 924, the inverter control unit 921 lights up each lamp LP1, LP2, LP3, ... of the light source unit 960, and then the current of the current sensing unit 924. The operation of the switching unit 922 is adjusted based on the detection signal. The driving voltage applied to the light source unit 960 via the transformer 923 is adjusted according to the operating state of the switching unit 922 so that the current flowing through the lamps LP1, LP2, LP3,. It is controlled to be constant.

When the lamps LP1, LP2, LP3, ... are turned on through this operation, the high and low voltage electrodes of the lamps LP1, LP2, LP3, ... are alternately positioned in the column direction. Averaging the amount of current leaking from both side ends of the unit 960 is equal to each other, so that the average temperature difference between both ends of the lamp unit 960 hardly occurs. Therefore, since the average brightness of both ends of the light source unit 960 is the same, the brightness of the light irradiated from the light source unit 960 is uniformly maintained regardless of the positions of the lamps LP1, LP2, LP3,.

According to the operation of the inverter unit 920, the light emitted from the light source unit 960 passes through the liquid crystal layer 3, and its polarization changes according to the arrangement of the liquid crystal molecules. This change in polarization is represented by a change in the transmittance of light by the polarizer.

After one horizontal period (or 1H) (one period of the horizontal synchronization signal Hsync) passes, the data driver 500 and the gate driver 400 repeat the same operation for the pixels in the next row. In this manner, the gate-on voltages V _{on are} sequentially applied to all the gate lines G ₁ -G _n during one frame to apply data voltages to all the pixels. When one frame ends, the next frame starts and the state of the inversion signal RVS applied to the data driver 500 is controlled so that the polarity of the data voltage applied to each pixel is opposite to that of the previous frame (frame inversion). . In this case, the polarities of the data voltages flowing through one data line may be changed (row inversion and point inversion) or the polarities of the data voltages applied to one pixel row may be different according to the characteristics of the inversion signal RVS within one frame. (Invert columns, invert points).

According to the embodiment of the present invention, since the positions of the high pressure electrode and the low pressure electrode of each lamp are alternately positioned in the column direction, the average leakage current amounts at both ends of the light source part are equalized. As a result, since the amount of current leaking from both ends of the light source unit is the same, and the luminance of both ends of the light source unit is the same, light of uniform brightness is irradiated onto the display device, thereby reducing the deterioration of the image quality of the display device due to the difference in luminance of the light source unit.

In addition, since the difference in the amount of leakage current generated between the high voltage electrode and the low voltage electrode is eliminated even without installing a transformer at each end of each lamp, it is possible to reduce the manufacturing cost and greatly reduce the size of the product.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (9)

 At least two light sources arranged in parallel and having first and second terminals, and At least two inverter units respectively connected to first terminals of the at least two light sources and applying a driving signal to the first terminal to blink the light sources; The at least two inverter units are alternately arranged in the column direction Backlight device. In claim 1, Each of the inverter units, Switching unit for receiving a DC voltage from the outside and outputting an AC voltage, A transformer unit for changing the AC voltage from the switching unit and applying it to the light source, and A switching control unit connected to the switching unit to control an operation of the switching unit Backlight device comprising a. In claim 2, The transformer unit includes a plurality of transformers connected to the first terminal of each light source. The method of claim 1 or 3, The first terminal is a high voltage electrode terminal. In claim 4, And the plurality of light sources is a CCFL. A plurality of pixels, At least two lamps arranged in parallel and supplying light to the pixels based on a blinking control signal, and At least two inverter units connected to one end of each of the at least two lamps and flashing the lamps by applying the blink control signal using a voltage from an external source Including, The inverter units are alternately arranged in the row direction Display device. In claim 6, Each of the inverter units, Switching unit for receiving a DC voltage from the outside and outputting the AC voltage, A transformer unit for changing the AC voltage from the switching unit and applying it to the lamp, and A switching control unit connected to the switching unit to control an operation of the switching unit Including, The transformer unit includes at least two transformers connected to the high voltage electrode ends of the respective lamps. Display device. In claim 6, The inverter unit is connected to the high voltage electrode of the lamp. In claim 8, The lamp is a CCFL.

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