KR20070062748A - Liquid crystal display device - Google Patents

Abstract

An LCD(Liquid Crystal Display) is provided to prevent the error operation of a driving circuit due to instability of a ground voltage, thereby improving the display defect such as flickering, shifting, and line defect. A display panel(1002) displays an image. A panel driving circuit part drives the display panel. A circuit part(242) includes a timing controller(241) for controlling the panel driving circuit part. The circuit part is mounted on a PCB(Printed Circuit Board)(280). The PCB includes a ground layer for supplying a ground voltage to the circuit part and a ground pad(220) formed in the same layer as the ground layer and distanced from the ground layer.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

1 is an exploded perspective view briefly showing a conventional liquid crystal display.

Figure 2 is a simplified view showing the back of the conventional assembled liquid crystal display device.

3 is an exploded perspective view briefly showing a liquid crystal display according to the present invention.

4 is a schematic view showing a rear surface of the assembled liquid crystal display device according to the first embodiment of the present invention.

5 is a cross-sectional view of a portion of FIG. 4.

FIG. 6 is a schematic view illustrating a rear surface of an assembled liquid crystal display device according to a second exemplary embodiment of the present invention. FIG.

FIG. 7 is a sectional view of a portion of FIG. 6; FIG.

8 is a view briefly showing a rear surface of an assembled liquid crystal display according to a third embodiment of the present invention.

FIG. 9A shows a first embodiment of FIG. 8; FIG.

9b shows a second embodiment of FIG. 8;

9C shows a third embodiment of FIG. 8;

9D shows a fourth embodiment of FIG. 8;

<Explanation of Signs of Major Parts of Drawings>

2,1002: liquid crystal panel 101,201,301,401: support main

110, 210, 310, 410: case 180, 280, 380, 480: printed circuit board

120,220,320,420: Ground pads 130,230,330,430: Ground floor

150,250,350,450: Connector 142,242,342,442: Circuit part

190,290,390,490: insulating tape

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device that can improve image quality defects caused by static electricity.

As the information society develops, the demand for display devices is increasing in various forms, and in recent years, liquid crystal display devices (LCDs), plasma display panels (PDPs), electro luminescent displays (ELD), and vacuum fluorescent (VFD) Various flat panel display devices such as displays have been studied, and some of them are already used as display devices in various devices.

Among them, LCD is the most widely used as the substitute for CRT (Cathode Ray Tube) for mobile image display device because of its excellent image quality, light weight, thinness, and low power consumption. In addition to the use of the present invention has been developed in various ways such as a television and a computer monitor for receiving and displaying broadcast signals.

In order to use such a liquid crystal display as a general screen display device in various parts, it is a matter of how high quality images such as high definition, high brightness and large area can be realized while maintaining the characteristics of light weight, thinness and low power consumption. Can be.

FIG. 1 is an exploded perspective view briefly showing a conventional liquid crystal display, and FIG. 2 is a view briefly showing a rear surface of a conventional assembled liquid crystal display.

1 and 2, a conventional liquid crystal display device includes a liquid crystal panel 2 for displaying an image by adjusting a light transmittance of a liquid crystal, and a backlight unit 20 for irradiating light to the liquid crystal panel 2 ( A back light unit, a board assembly unit for driving the liquid crystal panel 2, and a casing for casing them.

The liquid crystal panel 2 includes a liquid crystal layer formed in a space between the first substrate 4 on which the TFT array is formed, the second substrate 6 on which the color filter array is formed, and the first and second substrates 4 and 6 ( Not shown).

The first substrate 4 includes a plurality of gate wires arranged in the first direction to have a predetermined interval, a plurality of data wires formed in the second direction so as to have a predetermined interval and arranged to cross each gate wire, and each gate wire. And a liquid crystal cell formed for each pixel region where the data lines cross each other. Here, each of the liquid crystal cells includes a thin film transistor (TFT) connected to a gate wiring and a data wiring, and a pixel electrode connected to the thin film transistor.

The second substrate 6 includes a light blocking layer for blocking light in portions other than the pixel area, a color filter layer for expressing color colors, and a common electrode. In this case, the common electrode may be formed on the first substrate 4 according to the mode of the liquid crystal layer.

The liquid crystal panel 2 further includes an upper polarizing plate attached to the front surface of the second substrate 6 and a lower polarizing plate attached to the rear surface of the first substrate 4.

The backlight unit 20 includes a lamp for generating light, a light guide plate 16 for advancing light incident from the lamp through the incident surface toward the liquid crystal panel 2, and a light guide plate 16 disposed on a rear surface of the light guide plate 16. Reflection sheet 22 reflecting light incident from the light guide plate and a plurality of optical sheets 18 disposed on the light guide plate 16 to improve the light efficiency from the light guide plate 16 and advance to the liquid crystal panel 2. do.

The casing includes a support main 101 in which the backlight unit and the liquid crystal panel 2 are sequentially received, and a case 110 surrounding the front edge of the liquid crystal panel 2 and the side surface of the support main 101. It is provided.

The support main 101 includes a plurality of stepped surfaces for accommodating each of the backlight unit and the liquid crystal panel 2.

The case 110 is manufactured in the form of a rectangular band so as to have a flat portion and a side portion bent with a metal material. The flat part of the case 110 surrounds the front edge of the liquid crystal panel 2 accommodated in the support main 101, and the side part of the case 110 surrounds the side of the support main 101.

The board assembly unit includes a plurality of gate tape carrier packages 102 mounted with a gate driver integrated circuit 103 for supplying a gate signal to each gate wiring, and a data driver integrated circuit for supplying an image signal to each data wiring ( A circuit portion including a plurality of data tape carrier packages 104 mounted thereon and a timing controller 141 connected to the plurality of data tape carrier packages 104 and controlling gates and data driver integrated circuits 103 and 105 ( 142 is provided with a printed circuit board 180 mounted.

Each of the plurality of gate tape carrier packages 102 is attached to a gate pad portion electrically connected to each gate wiring of the liquid crystal panel 2. The plurality of gate tape carrier packages 102 are folded along the side of the support main 101 to the back of the support main 101.

Each of the gate driver integrated circuits 103 generates a gate signal in accordance with a gate control signal from a timing controller, and sequentially supplies the gate signal to each gate wiring. In this case, each of the gate driver integrated circuits 103 may be timingd through a line on glass (LOG) line formed on one side of the printed circuit board 180, one of the plurality of data tape carrier packages 104, and the liquid crystal panel 2. The gate control signal is supplied from the controller.

One side of each of the plurality of data tape carrier packages 104 is attached to the printed circuit board 180, and the other side is attached to a data pad part electrically connected to each data line of the liquid crystal panel 2.

Each of the data driver integrated circuits 105 converts the digital data from the timing controller into an image signal, which is an analog signal, in accordance with the data control signal from the timing controller, and supplies them to the respective data wires.

The printed circuit board 180 includes a timing controller 141 for controlling the driving of the liquid crystal panel 2 and a power supply unit 140 for generating a driving voltage including a ground voltage for driving the liquid crystal panel 2. The circuit unit 142 and a connector 150 for connecting to an external drive system are mounted.

When the connector 150 is installed on one side of the printed circuit board 180, the connector 150 is electrically connected to an external cable to supply a data signal supplied from the cable to the timing controller, and includes a ground voltage to supply the driving voltage to the circuit unit 142. To feed.

On the other hand, the printed circuit board 180 is a multi-layer printed circuit board at least two insulated by an insulating film to electrically connect the ground layer 130 to which the ground voltage is applied through the connector 150 and the circuit unit 142. The signal wiring layer of the layer is formed. In this case, each signal wiring layer and the circuit unit 142 are electrically connected to each other through a via hole.

The ground layer 130 is formed above or below the printed circuit board 180. In this case, a protective film such as a solder resist is formed on the ground layer 130.

In addition, a portion of the passivation layer is removed on one side of the printed circuit board 180 to form a ground pad 120 in which the ground layer 130 is exposed to the outside.

The printed circuit board 180 is electrically connected to the plurality of data tape carrier packages 104 and is folded along the side of the support main 101 along the support main 101.

Meanwhile, the liquid crystal display according to the related art has a conductive tape 190 connected between the ground pad 120 and the case 150 of the printed circuit board 180 folded on the back surface of the support main 101 as shown in FIG. 2. It is further provided.

The conductive tape 190 is electrically connected between the printed circuit board 180 and the case 110 to serve to ground the ground layer of the printed circuit board 180 to the case 110.

In the conventional liquid crystal display, when static electricity generated from the outside is induced in the case 110, the static electricity is transferred to the connector 150 through the conductive tape 190 and the ground pad 120 of the printed circuit board 180. Static electricity, which is retained in the connector 150, is removed through the ground of the drive system.

However, in the conventional liquid crystal display device, static electricity induced in the case 110 flows into the ground layer 130 through the ground pad 120, thereby making the ground voltage unstable.

Therefore, in the conventional liquid crystal display device, due to instability of the ground voltage, screen defects such as flickering, shifting, and line defect due to malfunction of the driving circuit are increased, and display characteristics and electrical The problem is that the characteristic is weakened.

Therefore, in order to solve the above problems, the present invention improves the screen defects such as flickering, shifting, and line defect due to malfunction of the driving circuit due to instability of the ground voltage. It is to provide a liquid crystal display device that can be.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a display panel for displaying an image, a case surrounding an edge of the display panel, and a printed circuit mounted with a circuit unit for driving the display panel. And a ground layer formed on the printed circuit board to supply a ground voltage to the circuit portion, and a ground pad formed on the printed circuit board to be separated from the ground layer and electrically connected to the case. do.

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

FIG. 3 is an exploded perspective view schematically illustrating a liquid crystal display according to a first embodiment of the present invention, and FIG. 4 is an assembled rear view of the liquid crystal display according to the first embodiment of the present invention.

3 and 4, a liquid crystal display device according to a first embodiment of the present invention includes a liquid crystal panel 1002 for displaying an image by adjusting a light transmittance of a liquid crystal; A backlight unit 200 for irradiating light onto the liquid crystal panel 1002; A support main 201 for accommodating the backlight unit 200 and the liquid crystal panel 1002; A case 210 surrounding the edge of the liquid crystal panel 1002 and the side surface of the support main 201; A panel driving circuit section for driving the liquid crystal panel 1002; A circuit portion 242 including a timing controller 241 for controlling the panel driving circuit portion; The circuit unit 242 is mounted and the ground layer 230 for supplying a ground voltage to the circuit unit 242 and the ground pad 220 formed on the same layer to be separated from the ground layer 230 and electrically connected to the case 210. There is a printed circuit board 280 having a).

The liquid crystal panel 1002 includes a liquid crystal layer formed in a space between a first substrate 1004 having a TFT array, a second substrate 1006 having a color filter array, and first and second substrates 1004 and 1006. Not shown).

The first substrate 1004 includes a plurality of gate wires arranged in the first direction to have a predetermined interval, a plurality of data wires formed in the second direction so as to have a predetermined interval and arranged to cross each gate wire, and each gate wire. And a liquid crystal cell formed for each pixel region where the data lines cross each other. Here, each of the liquid crystal cells includes a thin film transistor (TFT) connected to a gate wiring and a data wiring, and a pixel electrode connected to the thin film transistor.

The second substrate 1006 includes a light blocking layer for blocking light in portions other than the pixel region, a color filter layer for expressing color colors, and a common electrode. In this case, the common electrode may be formed on the first substrate 1004 according to the mode of the liquid crystal layer.

The liquid crystal panel 1002 further includes an upper polarizing plate attached to the front surface of the second substrate 1006 and a lower polarizing plate attached to the rear surface of the first substrate 1004.

The backlight unit 200 includes a lamp for generating light, a light guide plate 1016 for advancing light incident from the lamp through the incident surface toward the liquid crystal panel 1002, and a light guide plate 1016 disposed on a rear surface of the light guide plate 1016. Reflection sheet 1022 reflecting the light incident from the light guide plate and a plurality of optical sheets 1018 disposed on the light guide plate 1016 to improve the light efficiency from the light guide plate 1016 to advance to the liquid crystal panel 1002. do.

The support main 201 includes a plurality of stepped surfaces for accommodating the backlight unit and the liquid crystal panel 1002, respectively.

The case 210 is manufactured in the form of a rectangular band so as to have a flat portion and a side portion bent with a metal material. The flat part of the case 210 surrounds the front edge of the liquid crystal panel 1002 accommodated in the support main 201, and the side part of the case 210 surrounds the side of the support main 201.

The panel driving circuit unit includes a plurality of gate tape carrier packages 202 mounted with a gate driver integrated circuit 203 for supplying a gate signal to each gate wiring, and a data driver integrated circuit for supplying an image signal to each data wiring ( 204 has a plurality of data tape carrier packages 204 mounted thereon.

Each of the plurality of gate tape carrier packages 202 is attached to a gate pad portion electrically connected to each gate wiring of the liquid crystal panel 1002.

Each of the gate driver integrated circuits 203 generates a gate signal according to a gate control signal from the timing controller 241 and sequentially supplies the gate signal to each gate wiring. In this case, each of the gate driver integrated circuits 203 may be timingd through a line on glass (LOG) wiring formed on one side of the printed circuit board 280, the plurality of data tape carrier packages 204, and the liquid crystal panel 1002. The gate control signal is supplied from the controller 241.

One side of each of the plurality of data tape carrier packages 205 is attached to the printed circuit board 280, and the other side is attached to a data pad part electrically connected to each data line of the liquid crystal panel 1002.

Each of the data driver integrated circuits 204 converts digital data from the timing controller 241 into an image signal, which is an analog signal, in accordance with a data control signal from the timing controller 241 and supplies them to respective data wires.

The circuit unit 242 includes a timing controller 241 for controlling the driving of the liquid crystal panel 1002 and a power supply unit 240 for generating a driving voltage including a ground voltage for driving the liquid crystal panel 1002. The circuit unit 242 is mounted on the printed circuit board 280.

The timing controller 241 aligns data from the outside and supplies the data to each of the data driver integrated circuits 204 and controls each of the data driver integrated circuits 204 and the gate driver integrated circuits 203.

The power supply unit 241 generates a driving voltage required for the panel driving circuit and a driving voltage necessary for the circuit unit 242 using input power supplied from the outside.

The printed circuit board 280 is a multilayer printed circuit board on which the ground layer 230, the ground pad 220, the connector 250, and the circuit unit 242 are mounted.

When the connector 250 is installed on one side of the printed circuit board 280, the connector 250 is electrically connected to an external cable to supply a data signal supplied from the cable to the timing controller 250, and includes a ground voltage to supply a driving voltage to the circuit unit. Supply to 242.

The ground layer 230 is formed on or under the printed circuit board 280. At this time, a protective film such as a solder resist is formed on the ground layer. The ground layer 230 is electrically connected to a ground pin to which a ground voltage is applied among the plurality of pins provided in the connector 250.

The ground pad 220 is formed on the same layer as the ground layer 230 on one side of the printed circuit board 280 adjacent to the case 210 so as to be separated from the ground layer 230 and exposed to the outside. The ground pad 220 is applied with a ground voltage among a plurality of pins provided in the connector 250 through a signal line 270 formed to be separated from the ground layer 230 along one edge of the printed circuit board 280. Is electrically connected to the ground pin.

The printed circuit board 280 is electrically connected to the plurality of data tape carrier packages 204 to fold the support main 201 along the side thereof to the rear surface of the support main 201.

The liquid crystal display further includes a conductive tape 290 connected between the ground pad 220 and the case 210 of the printed circuit board 280 folded on the back surface of the support main 201.

The conductive tape 290 is electrically connected between the printed circuit board 280 and the case 210 to serve to ground the ground pad 220 of the printed circuit board 280 to the case 210.

Therefore, the liquid crystal display according to the first exemplary embodiment of the present invention is formed by separating the ground layer 230 and the ground pad 220 formed on the same layer of the printed circuit board 280 as shown in FIG. 5. Static electricity introduced into the case 250 may be prevented from being transferred to the ground layer 230. As a result, the present invention can prevent the malfunction of the circuit unit 242 due to the instability of the ground voltage to prevent screen defects such as flickering, shifting, and line defect, and the display. Properties and electrical properties can be improved.

FIG. 6 is a schematic view illustrating an assembled rear surface of a liquid crystal display according to a second exemplary embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along a cutting line of II-II ′ of FIG. 6.

6 and 7, in the liquid crystal display according to the second exemplary embodiment of the present invention, another configuration except for the signal wiring 370 for electrically connecting the ground pad 220 and the connector 250 is illustrated in FIG. 3. And the same configuration as the first embodiment of the present invention shown in FIG. Accordingly, the description of the other components except for the signal wiring 370 will be replaced with the description of the first embodiment of the present invention.

The signal wiring 370 is formed on a layer different from the ground pad 320 and the ground layer 330 formed on the printed circuit board 380. For example, the signal wiring 370 may be additionally formed on the bottom surface of the printed circuit board 380.

One side of the signal line 380 opposite to the ground pad 320 is electrically connected to the ground pad 320 through the first via hole 300 passing through the printed circuit board 380. In addition, the other side of the signal line 370 facing the connector 350 is electrically connected to the ground pin through which the ground voltage is supplied among the plurality of pins of the connector 350 through the printed circuit board 380.

In the liquid crystal display according to the second exemplary embodiment of the present invention having the signal wiring 370, the static electricity introduced into the case 350 may be the ground pad 320, the first via hole 300a, and the signal wiring 370. And through the ground pin of the connector 350 through the second via hole 300b and through the ground of the external system.

Accordingly, the liquid crystal display according to the second exemplary embodiment of the present invention is formed by separating the ground layer 330 and the ground pad 320 formed on the same layer of the printed circuit board 380 as shown in FIG. 7. The static electricity introduced into the case 310 may be prevented from being transferred to the ground layer. As a result, the present invention can prevent the malfunction of the driving circuit due to the instability of the ground voltage to prevent screen defects such as flickering, shifting, and line defect, and can improve display characteristics and electrical characteristics.

8 is a view briefly illustrating a rear surface of a liquid crystal display according to a third exemplary embodiment of the present invention.

8, the liquid crystal display according to the third embodiment of the present invention comprises a liquid crystal panel 1002 for displaying an image by adjusting the light transmittance of the liquid crystal; A backlight unit 200 for irradiating light onto the liquid crystal panel 1002; A support main 401 for housing the backlight unit 200 and the liquid crystal panel 1002; A case 410 surrounding the edge of the liquid crystal panel 1002 and the side surface of the support main 401; A panel driving circuit section for driving the liquid crystal panel 1002; A circuit portion 442 including a timing controller 441 for controlling the panel driving circuit portion; The circuit part 442 is mounted and the ground layer 430 for supplying a ground voltage to the circuit part 442, and the ground pad 420 formed on the same layer to be separated from the ground layer 430 and electrically connected to the case 410. And a printed circuit board 480 having a connection part 400 connecting the ground layer 430 and the ground pad 420.

The liquid crystal display according to the third exemplary embodiment of the present invention has the same configuration as the first exemplary embodiment of the present invention shown in FIGS. 3 and 4 except for the printed circuit board 480. Accordingly, the description of the other components except for the printed circuit board 480 will be replaced with the description of the first embodiment of the present invention.

The printed circuit board 480 is a multilayer printed circuit board on which the ground layer 430, the ground pad 420, the connector 450, and the circuit unit 442 are mounted.

When the connector 450 is installed at one side of the printed circuit board 480, the connector 450 is electrically connected to an external cable and supplies a driving voltage to the circuit unit 442 including a data signal and a ground voltage supplied from the cable.

The ground layer 430 is formed on or under the printed circuit board 480. In this case, a protective film such as a solder resist is formed on the ground layer 430. The ground layer 430 is electrically connected to a ground pin to which a ground voltage is applied among the plurality of pins provided in the connector 450.

The ground pad 420 is formed on the same layer as the ground layer 430 on one side of the printed circuit board 480 adjacent to the case 410 so as to be separated from the ground layer 430 and exposed to the outside. The ground pad 420 is electrically connected to the case 410 through the conductive tape 490.

The connection part 400 includes a resistor 400a electrically connected to a portion between the ground pad 420 and the ground layer 430 as shown in FIG. 9. At this time, the resistance value of the resistance element 400a has a value so small that it is close to 0Ω. The connection part 400 is connected to a portion between the ground pad 420 and the ground layer 430 to ground the ground layer 430 to the case 410 through the ground pad 420 and the conductive tape 490. In addition, the static electricity introduced into the case 410 is prevented from flowing into the ground layer 430 through the conductive tape 490 and the ground pad 420. That is, since the connection part 400 has a very small value close to 0 Ω, the connection 400 blocks the static electricity introduced into the ground pad 420 from entering the ground layer 430.

On the other hand, in the liquid crystal display according to the third embodiment of the present invention, the connection portion 400 is a straight line 400b, a zigzag on a portion between the ground layer 430 and the ground pad 420 as shown in 9b to 9d. The wiring may be patterned in any one of the shape 400c and the curve 400d.

Accordingly, in the liquid crystal display according to the third exemplary embodiment, the ground layer 430 and the ground pad 420 formed on the same layer of the printed circuit board 480 are separated from each other, and the separated ground layer 430 is separated from the ground layer 430. By connecting a portion of the ground pad 420 to the connection part, static electricity introduced into the case 410 may be prevented from being transferred to the ground layer 430. As a result, the present invention prevents malfunction of the circuit unit 480 due to instability of the ground voltage, thereby preventing screen defects such as flickering, shifting, and line defects, and improving display characteristics and electrical characteristics.

On the other hand, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

As described above, the liquid crystal display according to the exemplary embodiment of the present invention has a screen defect such as flickering, shifting, line defect, etc. due to malfunction of the driving circuit due to instability of the ground voltage. This is improved and enhances display characteristics and electrical characteristics.

Claims (9)

A display panel which displays an image; A panel driving circuit unit for driving the display panel; A circuit unit including a timing controller to control the panel driving circuit unit; And a printed circuit board on which the circuit unit is mounted and including a ground layer configured to supply a ground voltage to the circuit unit, and a ground pad formed on the same layer so as to be separated from the ground layer. The method of claim 1, And a connector provided on the printed circuit board and configured to supply a driving signal including the ground voltage to the circuit unit. The method of claim 2, And a connection wiring formed on the printed circuit board so as to be separated from the ground layer and electrically connecting the ground pad and the connector. The method of claim 3, wherein And the connection line is formed on the same layer as the ground pad. The method of claim 3, wherein And the connection wiring is formed on a layer different from the ground pad and is electrically connected to the ground pad and the connector through at least one via hole. The method of claim 1, And a connection part for electrically connecting the ground layer and a part of the ground pad. The method of claim 6, And the connection part is a resistance element. The method of claim 6, And the connection part is a wire patterned in any one of a straight line, a zigzag and a curved shape. The method of claim 1, A case casing the display panel; And a conductive tape for electrically connecting the case and the ground pad to each other.

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