KR20100054632A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: An LCD(Liquid Crystal Display) device is provided to prevent the defects in the lighting of an EEFL by blocking the light provided to the EEFL when the EEFL is turned on. CONSTITUTION: A BLU(Backlight Unit) provides a liquid crystal panel with light, and a BLU comprises an EEFL(External Electrode Fluorescent Lamp)(172), a bottom cover(171) receiving the EEFL, and a lamp controller(165). The lamp controller provides the EEFL with light and senses whether the EEFL is turned on or off. When the EEFL is turned on, the lamp controller blocks the light provided to the EEFL.

Description

[0001] The present invention relates to a liquid crystal display device,

An embodiment of the present invention relates to a liquid crystal display device.

With the development of information technology, the market for a display device, which is a connection medium between a user and information, is growing. Accordingly, flat panel displays (FPDs), such as liquid crystal displays (LCDs), organic light emitting diodes (OLEDs), and plasma display panels (PDPs), may be used. Usage is increasing. Among them, a liquid crystal display device capable of realizing high resolution and capable of large size as well as small size is widely used.

Here, the liquid crystal display device is classified into a light receiving display device. Such a liquid crystal display may display an image by receiving a light source from a backlight unit disposed under the liquid crystal panel.

The LCD includes a liquid crystal panel including a color filter substrate and a transistor array substrate, and a backlight unit for providing light to the liquid crystal panel. The liquid crystal layer is formed between the color filter substrate and the transistor array substrate included in the liquid crystal panel. The backlight unit may include a lamp for providing light to the liquid crystal panel, an optical sheet for guiding light emitted from the lamp to the liquid crystal panel, and the like.

Lamps included in the backlight unit include Cold Cathode Fluorescent Lamps (CCFLs), Hot Cathode Fluorescent Lamps (HCFLs), External Electrode Fluorescent Lamps (EEFLs), and Light-Emitting Diodes (CFLs). Light Emitting Diode (LED) lamp is used. On the other hand, the backlight unit employing the external electrode fluorescent lamp, there is a problem that does not turn on when not driven for a long time, the improvement of this is required.

Embodiments of the present invention for solving the problems of the above-described background, by providing light to the external electrode fluorescent lamp to turn on the external electrode fluorescent lamp, when the external electrode fluorescent lamp is turned on to block the light provided to the external electrode fluorescent lamp. By providing a liquid crystal display device that can solve the problem of poor lighting of the external electrode fluorescent lamp.

Embodiments of the present invention as a means for solving the above problems, the liquid crystal panel; And a backlight unit for providing light to the liquid crystal panel, wherein the backlight unit includes an external electrode fluorescent lamp, a cover bottom on which the external electrode fluorescent lamp is seated, and provides an external electrode fluorescent lamp to turn on the external electrode fluorescent lamp. The present invention provides a liquid crystal display including a lamp control unit which senses whether the external electrode fluorescent lamp is turned on and senses whether the external electrode fluorescent lamp is turned on to block light provided to the external electrode fluorescent lamp.

The lamp control unit may emit light based on a signal transmitted from the sensor unit when the external electrode fluorescent lamp is turned on, and a light emitting unit providing light to the external electrode fluorescent lamp, a sensor unit sensing whether the external electrode fluorescent lamp is turned on, and the external electrode fluorescent lamp is turned on. It may include a transistor for turning off the negative.

The lamp control unit includes a light emitting unit having one end connected to a first power line, a sensor unit having one end connected to a terminal to which an external control signal is supplied, a first electrode connected to the other end of the light emitting unit, and a second electrode connected to the second power line. The transistor may include a transistor connected to a gate connected to the other end of the sensor unit.

The transistor may be a reduced field effect transistor.

The light emitting unit may be a blue light emitting diode emitting blue light.

The sensor unit may be a light receiving diode that senses whether the external electrode fluorescent lamp is turned on.

The cover bottom may include a hole located in an area corresponding to the area where the external electrode fluorescent lamp is located, and the hole may expose the light emitting part and the sensor part located under the cover bottom.

According to an embodiment of the present invention, the external electrode fluorescent lamp is turned on to light the external electrode fluorescent lamp, and when the external electrode fluorescent lamp is turned on, it blocks the light provided to the external electrode fluorescent lamp to solve the problem of poor lighting of the external electrode fluorescent lamp. There is an effect of providing a liquid crystal display device that can be solved.

Hereinafter, with reference to the accompanying drawings, the specific content for the practice of the present invention will be described.

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

As illustrated in FIG. 1, the LCD may include a liquid crystal panel 183, a driver 189, and a backlight unit 178.

The liquid crystal panel 183 may have a structure in which the first substrate 110 having the thin film transistor array and the second substrate 120 having the color filter are bonded to each other with the liquid crystal layer interposed therebetween. In the liquid crystal panel 183, subpixels driven independently by a thin film transistor are arranged in a matrix form, and a difference between a common voltage supplied to each common pixel and a data signal supplied to a pixel electrode connected to the thin film transistor is provided. The image can be displayed by controlling the liquid crystal array in accordance with the voltage to adjust the light transmittance.

The backlight unit 178 may include a cover bottom 171, an external electrode fluorescent lamp (EEFL) 172, a diffusion plate 173, a diffusion sheet 174, an optical sheet 175, and a protective sheet 176. ) May be included. In the case of the optical sheet 175, a sheet such as a prism, a lenticular lens, or a micro lens may be used.

The driver 189 may include a plurality of film circuits 186 mounted on a driving chip 187 for driving the data wires and the gate wires of the liquid crystal panel 183 and connected to one side of the first substrate 110. The printed circuit board 188 connected to the other side of the first substrate 110 may be included. The film circuit 186 mounted with the driving chip 187 may be positioned in a chip on film (COF) or tape carrier package (TCP) method. However, the driving chip 187 may be directly mounted on the first substrate 110 by a chip on glass (COG) method, or may be formed and embedded on the first substrate 110 in a thin film transistor forming process.

The liquid crystal panel 183 and the backlight unit 178 displaying the abnormal image may be accommodated by the upper case 190 and the lower case 170. The upper case 190 may accommodate the liquid crystal panel 183, and the lower case 170 may receive the backlight unit 178. The liquid crystal panel 183 may be disposed on the backlight unit 178 at a predetermined interval. The liquid crystal panel 183 and the backlight unit 178 may be fixed and protected by the upper case 190 fastened to the lower case 170. Here, an opening for exposing the image display area of the liquid crystal panel 183 may be provided on the upper surface of the upper case 190.

The liquid crystal panel 183 described above may display an image on each subpixel according to a scan signal supplied through the gate lines and a data voltage supplied through the data lines. The scan signal may be, but is not limited to, a pulse signal in which the gate high voltage supplied for one horizontal time and the gate low voltage supplied for the remaining time are alternated.

The thin film transistor included in the subpixel may be turned on when a gate high voltage is supplied from the gate lines, and may supply a data voltage applied from the data lines to the liquid crystal layer. Accordingly, when the thin film transistor of each subpixel is turned on and the data voltage is applied to the pixel electrode, the liquid crystal display may display an image while charging the difference voltage between the data voltage and the common voltage to the liquid crystal layer.

On the contrary, when the gate low voltage is supplied from the gate lines, the thin film transistor may be turned off and the data voltage charged in the liquid crystal layer may be maintained by the storage capacitor for one frame period. Meanwhile, the liquid crystal panel 183 may repeat different operations according to scan signals supplied through the gate lines.

Hereinafter, the liquid crystal panel will be described in more detail.

2 is a cross-sectional view of the liquid crystal panel.

Referring to FIG. 2, the liquid crystal panel may have a structure in which the first substrate 110 and the second substrate 120 are bonded to each other with the liquid crystal layer 125 interposed therebetween.

The gate 111 may be located on one surface of the first substrate 110. The gate 111 is any one selected from the group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu). It may be made of one or an alloy thereof. In addition, the gate 111 may include molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). It may be a multilayer made of any one or alloys thereof. In addition, the gate 111 may be a double layer of molybdenum / aluminum-neodymium or molybdenum / aluminum.

The first insulating layer 112 may be positioned on the gate 111. The first insulating layer 112 may be a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or a multilayer thereof, but is not limited thereto.

An active layer 114a positioned in a region corresponding to the gate 111 may be positioned on the first insulating layer 112, and an ohmic contact layer 114b lowering a contact resistance may be disposed in the active layer 114a. have. In addition, a data pad 113 to which a data voltage is supplied may be positioned on the first insulating layer 112, but is not limited thereto.

The source 115 and the drain 116 may be positioned on the active layer 114a. The source 115 and the drain 116 may be formed of a single layer or multiple layers. When the source 115 and the drain 116 are a single layer, molybdenum (Mo), aluminum (Al), chromium (Cr), and gold may be used. (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) may be made of any one or an alloy thereof. In addition, when the source 115 and the drain 116 are multiple layers, the double layer of molybdenum / aluminum-neodymium and the triple layer of molybdenum / aluminum / molybdenum or molybdenum / aluminum-neodymium / molybdenum may be used.

The second insulating layer 117 may be positioned on the source 115 and the drain 116. The second insulating layer 117 may be a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or a multilayer thereof, but is not limited thereto. The second insulating layer 117 may be a passivation layer.

The pixel electrode 118 connected to the source 115 or the drain 116 may be positioned on the second insulating layer 117. The pixel electrode 118 may be one of indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide (ZnO).

The common electrode (not shown) may be positioned on the second insulating layer 117 to face the pixel electrode 118. The common electrode may be located on the first substrate 110 or the second substrate 120 according to the driving method.

A spacer 119 may be positioned on the first substrate 110 to maintain a cell gap with the second substrate 120 on the second insulating layer 117 corresponding to the source 115 and the drain 116. have.

The black matrix 121 may be positioned on one surface of the second substrate 120. The black matrix 121 is a non-display area and may be positioned to correspond to the area where the spacer 119 is located. The black matrix 121 is made of a photosensitive organic material to which a black pigment is added, and as the black pigment, carbon black or titanium oxide may be used.

The color filters 120R, 120G, and 120B may be positioned between the black matrices 121. The color filters 120R, 120G, and 120B may have other colors as well as red (120R), green (120G), and blue (120B).

The overcoat layer 122 may be disposed on the black matrix 121 and the color filters 120R, 120G, and 120B. The overcoating layer 122 may be omitted depending on the structure of the second substrate 120 having the black matrix 121 and the color filters 120R, 120G, and 120B.

2 is only for the understanding of the liquid crystal panel, the liquid crystal panel according to the exemplary embodiment of the present invention is not limited thereto.

Hereinafter, the backlight unit will be described in more detail.

3 is a cross-sectional view illustrating a backlight unit according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view of the region X-X of FIG. 3.

3 and 4, the backlight unit may include a cover bottom 171, an external electrode fluorescent lamp 172, and a lamp controller 165.

The lamp control unit 165 provides light to turn on the external electrode fluorescent lamp 172 and senses whether the external electrode fluorescent lamp 172 is turned on so that the external electrode fluorescent lamp 172 is turned on. A function of blocking light provided to 172 may be performed. The lamp control unit 165 includes a light emitting unit 163 providing light to turn on the external electrode fluorescent lamp 172, a sensor unit 164 sensing whether the external electrode fluorescent lamp 172 is turned on, and an external electrode. When the fluorescent lamp is turned on, it may include a circuit board 161 including a transistor (not shown) for turning off the light emitting unit based on a signal transmitted from the sensor unit.

The circuit board 161 including the light emitting unit 163, the sensor unit 164, and the transistor may be disposed under the cover bottom 171. Accordingly, the cover bottom 171 may include a light emitting part 163 positioned below the cover bottom 171 and holes H1 and H2 exposing the sensor part 164. The holes H1 and H2 formed in the cover bottom 171 may be located below the external electrode fluorescent lamp 172 located outside, but are not limited thereto.

The light emitting unit 163 may provide light to turn on the external electrode fluorescent lamp 172 through the first hole H1, and the sensor unit 164 may supply the external electrode fluorescent lamp through the second hole H2. 172 may be detected.

3 and 4, the external electrode fluorescent lamp 172 can receive light from the light emitting unit 163 when power is supplied to drive the liquid crystal display device. Even if 172 is in an undriven state for a long time, the light can be turned on. In addition, the light emitting unit 163 may be controlled to be turned off after the external electrode fluorescent lamp 172 is turned on by interlocking the sensor unit 164 with the transistor.

Hereinafter, the lamp control unit will be described in more detail.

5 is an exemplary circuit diagram of a lamp control unit, and FIG. 6 is a waveform diagram illustrating the lighting of the external electrode fluorescent lamp and the operation of the lamp control unit.

Referring to FIG. 5, the lamp control unit includes a light emitting diode LD having one end connected to the first power line VCC, a light receiving diode KD having one end connected to a terminal LED_ON to which an external control signal is supplied, and a light emitting diode. The first electrode is connected to the other end of the LD, the second electrode is connected to the second power supply line VSS, and a reduced field effect transistor TFT having a gate connected to the other end of the light receiving diode KD. .

The light emitting diode LD may provide light to the external electrode fluorescent lamp 172, and the light emitting diode KD may sense whether the external electrode fluorescent lamp 172 is turned on, and the reduced field effect transistor TFT may be used. ) May turn off the light emitting diode LD based on a signal transmitted from the light receiving diode KD when the external electrode fluorescent lamp 172 is turned on.

Referring to FIG. 6, when the power supply M_on for driving the liquid crystal display device is supplied, the lamp control unit receives an external control signal B_on for emitting the light emitting diode LD to light up the external electrode fluorescent lamp 172. Supplied. Then, light is provided to the external electrode fluorescent lamp 172 by light emission of the light emitting diode LD, so that the external electrode fluorescent lamp 172 is turned on in a specific section T1. Then, the light receiving diode KD senses that the external electrode fluorescent lamp 172 is turned on, and transmits a signal corresponding thereto to the reduced field effect transistor TFT. Then, the light emitting diode LD is turned off in the specific section T1 by the reduced field effect transistor TFT. In FIG. 6, a section in which the external electrode fluorescent lamp 172 is turned on and a section in which the light emitting diode LD is turned off occur in the same section T1. However, a substantially delay may occur in a section where the external electrode fluorescent lamp 172 is turned on and a section where the light emitting diode LD is turned off due to signal delay.

On the other hand, the time for which the external control signal B_on for emitting the light emitting diode LD is supplied may be set within about 1 second to 8 seconds when the external electrode fluorescent lamp 172 is turned on. The reason for setting the time is that the external electrode fluorescent lamp 172 does not always light at a constant time even when light is received from the light emitting die LD.

Meanwhile, in the above description, the reason why the light emitting diode LD may be turned off by the reduced field effect transistor TFT is because the signal transmitted from the light receiving diode KD is a channel of the reduced field effect transistor TFT. This is because it has a characteristic of narrowing the drain current to reduce the drain current.

According to the exemplary embodiment of the present invention, when the light emitting diode LD emits blue or other color and shows white or gray on the screen of the liquid crystal panel 183 during initial driving of the liquid crystal display, the external electrode fluorescent lamp 172 is turned off. It is possible to prevent the phenomenon that the light generated from the light emitting diode (LD) to light up to the front of the liquid crystal panel 183. In addition, the light emission time of the light emitting diode LD may be set within the time required for the external electrode fluorescent lamp 172 to light up, thereby solving the problem of poor lighting of the external electrode fluorescent lamp 172.

Embodiment of the present invention, by providing light to the external electrode fluorescent lamp to turn on the external electrode fluorescent lamp and when the external electrode fluorescent lamp is turned on the lamp control unit is automatically controlled to block the light provided to the external electrode fluorescent lamp It is possible to solve the problem of poor lighting of the external electrode fluorescent lamp, as well as to improve the reliability of the liquid crystal display device.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

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

2 is a cross-sectional view of a liquid crystal panel.

3 is a cross-sectional view of a backlight unit according to an embodiment of the present invention.

4 is a cross-sectional view of the region X-X of FIG.

5 is an exemplary circuit configuration of a lamp control unit.

6 is a waveform diagram for explaining the lighting of the external electrode fluorescent lamp and the operation of the lamp control unit;

<Explanation of symbols on main parts of the drawings>

110: first substrate 120: second substrate

111 gate 115 source

116: drain 119: spacer

121: black matrix 125: liquid crystal layer

163: light emitting unit 164: sensor unit

172: external electrode fluorescent lamp 171: cover bottom

183: liquid crystal panel 178: backlight unit

Claims (7)

A liquid crystal panel; And It includes a backlight unit for providing light to the liquid crystal panel, The backlight unit, External electrode fluorescent lamp, A cover bottom on which the external electrode fluorescent lamp is seated; And a lamp control unit configured to provide light to turn on the external electrode fluorescent lamp and to sense whether the external electrode fluorescent lamp is turned on, and to block light provided to the external electrode fluorescent lamp when the external electrode fluorescent lamp is turned on. LCD display device. The method of claim 1, The lamp control unit, A light emitting unit providing light to the external electrode fluorescent lamp; A sensor unit sensing whether the external electrode fluorescent lamp is turned on; And a transistor for turning off the light emitting unit based on a signal transmitted from the sensor unit when the external electrode fluorescent lamp is turned on. The method of claim 2, The lamp control unit, The light emitting unit having one end connected to a first power line; The sensor unit having one end connected to a terminal to which an external control signal is supplied; And a transistor having a first electrode connected to the other end of the light emitting part, a second electrode connected to the second power line, and a gate connected to the other end of the sensor part. The method of claim 2, The transistor, A liquid crystal display device comprising: a reduced field effect transistor. The method of claim 2, The light emitting unit, And a blue light emitting diode emitting blue light. The method of claim 2, The sensor unit includes: And a light receiving diode sensing whether the external electrode fluorescent lamp is turned on. The method of claim 2, The cover bottom includes a hole located in an area corresponding to an area in which the external electrode fluorescent lamp is located, The hole, And the light emitting part and the sensor part under the cover bottom.

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