KR101350887B1 - Liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a liquid crystal display device in which driving power consumption is reduced while forming a vertical electric field.

The present invention includes a first substrate having a plurality of liquid crystal pixels and a plurality of common voltage transfer pads to which a common voltage is applied; A second substrate on which a plurality of common electrodes are formed; A liquid crystal layer formed between the first substrate and the second substrate; And a plurality of conductive spacers disposed between the first substrate and the second substrate and electrically connecting the plurality of common voltage transfer pads and the plurality of common electrodes and spaced apart from each other. Common voltage inversion can be performed even in TN mode or VA mode liquid crystal display forming an electric field, and power consumption is reduced, and a separate common voltage supply unit can reduce power consumption and provide a stable common voltage. There is an advantage.

Description

[0001] Liquid crystal display device [0002]

1 is a view for explaining a common voltage inversion driving method used in a conventional transverse electric field type liquid crystal display device

2 is a perspective view schematically showing a liquid crystal display device according to a first embodiment of the present invention;

3 is a cross-sectional view taken along the line III-III of FIG. 2

4A and 4B are a plan view of a TFT substrate 10 and a plan view of a color filter substrate 20, respectively, to explain in more detail the liquid crystal display device according to the first embodiment of the present invention.

5 is a perspective view schematically showing a liquid crystal display according to a second embodiment of the present invention.

6 is a cross-sectional view taken along the line VI-VI of FIG. 5.

7A and 7B are a plan view of a TFT substrate 50 and a plan view of a color filter substrate 60, respectively, to explain in more detail the liquid crystal display according to the second embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

10,50: TFT substrate 12,52: First substrate

14,54: common voltage transfer pad 20,60: color filter substrate

22,62: second substrate 24,64: common electrode

30,70: Conductive Spacer 32,72: Sealant Composition

40, 80: liquid crystal layer 90: common voltage supply

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a liquid crystal display device in which driving power is reduced by performing a swing of a common voltage while forming a vertical electric field.

In general, an IPS (In-Plane Switching) mode liquid crystal display is a liquid crystal display having a wide viewing angle developed to solve the problem of narrow viewing angle, which is a major disadvantage of the TN mode liquid crystal display. In the IPS mode (hereinafter, referred to as a transverse electric field method) liquid crystal display, the common electrode and the pixel electrode are formed together on the same substrate (that is, the TFT substrate), and the liquid crystals are driven by a horizontal electric field generated between the electrodes. Has a larger viewing angle than the LCD.

In the lateral liquid crystal display device, since the common electrode is formed on the TFT substrate and the common electrode can be formed by separating the horizontal pixels in units of horizontal pixels, different common voltages are applied to the common electrodes in units of horizontal pixels. Therefore, a common voltage inversion driving method has been proposed to reduce power consumption.

Thus, the common voltage inversion driving method in the transverse electric field liquid crystal display will be briefly described with reference to FIG.

Referring to FIG. 1, a pixel is formed including a thin film transistor TFT, a liquid crystal capacitor C _LC , and a storage capacitor Cst in an area formed by a plurality of data lines DL1 to DL4 and gate lines GL1 to GL4. do.

In addition, the common lines CL1 to CL4 are configured to supply the common voltage Vcom to the liquid crystal capacitor C _LC and the storage capacitor Cst of each pixel, and the common lines CL1 to CL4 are odd lines. (CL1, CL3) and even lines (CL2, CL4) are separated and different common voltages (Vcom (+), Vcom (-)) are applied. The common wirings CL1 to CL4 are wirings connecting common electrodes formed in respective horizontal pixel columns.

In one frame, Vcom (+) having a potential higher than the reference common voltage Vcom is applied to the first and third common lines CL1 and CL3, and the second and fourth common lines CL2 and CL4 are applied thereto. Vcom (-) having a potential lower than the reference common voltage Vcom is applied. Of course, negative polarity (-) data is applied to the pixel to which Vcom (+) is applied, and positive polarity (+) data is applied to the pixel to which Vcom (+) is applied, so that the common voltage and The liquid crystal C _LC is driven by increasing the potential difference.

Subsequently, in the next frame, Vcom (−) is applied to the first and third common interconnections CL1 and CL3, Vcom (+) is applied to the second and fourth common interconnections CL2 and CL4, and the Vcom Positive data is applied to a pixel to which (-) is applied, and negative data is applied to a pixel to which Vcom (+) is applied.

As described above, the polarities of the common voltages applied to the odd-numbered common lines CL1 and CL3 and the even-numbered common lines CL2 and CL4 are inverted every frame, thereby applying the common voltage in driving the liquid crystal display. It is possible to reduce the power consumed for.

However, the common voltage inversion driving method performed in the above-described manner can reduce the power consumed by the common voltage, but the liquid crystal of the horizontal electric field formation method that can divide the common electrode in each horizontal pixel column unit or pixel unit. There is a drawback that can be applied only to the display device. Accordingly, the present invention aims to reduce power consumption by realizing common voltage inversion in a liquid crystal display device that forms a vertical electric field and forms only one common electrode, for example, a twisted nematic (TN) mode liquid crystal display device. .

In addition, another object of the present invention is to provide a liquid crystal display device capable of supplying a stable common voltage by minimizing the influence of the load of the common wiring to which the common voltage is applied.

In order to achieve the above object, the present invention includes a plurality of liquid crystal pixels and a first substrate having a plurality of common voltage transfer pads to which a common voltage is applied; A second substrate on which a plurality of common electrodes are formed; A liquid crystal layer formed between the first substrate and the second substrate; A liquid crystal display device is provided between the first substrate and the second substrate, and includes a plurality of conductive spacers electrically connected to the plurality of common voltage transfer pads and the plurality of common electrodes and spaced apart from each other.

The plurality of liquid crystal pixels are formed in a display area, and the plurality of common voltage transfer pads are formed in a non-display area around the display area.

The plurality of common electrodes may be configured in a bar shape.

The plurality of common electrodes may be formed in parallel with each other.

Each of the plurality of common electrodes may be connected to the common voltage transfer pad using at least one conductive spacer.

The plurality of common electrodes may be formed to correspond to the horizontal pixel rows of the first substrate.

The common voltage transfer pad is characterized in that the metal or ITO.

The common voltage applied to the plurality of common voltage transfer pads is characterized in that its potential changes every frame display period.

The apparatus may further include a plurality of common voltage supply units supplying a common voltage to each of the plurality of common voltage transfer pads.

Each common voltage supply unit is configured to simultaneously apply a common voltage to two or more common voltage transfer pads among the plurality of common voltage transfer pads.

The plurality of common voltage supplies may be integrated circuits or circuits composed of polysilicon thin film transistors.

The conductive spacer may be a metal ball spacer.

The conductive spacer is characterized in that the spacer formed of gold or silver.

The conductive spacer is characterized by being included in the sealant composition.

The first substrate further includes a plurality of liquid crystal pixels including a plurality of data lines and a gate line, the thin film transistor connected to the data lines and the gate line, and the second substrate further includes a color filter and a black matrix. It is characterized by.

The plurality of common electrodes are all formed on the same layer.

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

First Embodiment

FIG. 2 is a perspective view schematically showing a liquid crystal display device according to a first embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 2, wherein the TFT substrate 10, the color filter substrate 20, and the conductive film are conductive. A sealant composition 32 including a spacer (30 in FIG. 3) is shown.

In the configuration, the TFT substrate 10 and the color filter substrate 20 face each other, and a plurality of common voltage transfer pads 14 are formed on the TFT substrate 10. In addition, the color filter substrate 20 is provided with a bar-shaped common electrode 24 separated from each other at positions corresponding to the positions of the common voltage transfer pad 14, respectively. ) And a conductive spacer 30 in the form of a ball is formed between the common electrode 24 and the common electrode 24 to electrically connect the common voltage transfer pad 14 and the common electrode 24. In this case, as shown in the cross-sectional view of FIG. 3, the conductive spacer 30 may be mixed with the sealant composition 32.

Accordingly, common voltages applied to the plurality of common voltage transfer pads 14 from an external circuit are respectively applied to the common electrodes 24 at opposite positions through the conductive spacers 30. In this case, the common voltages applied to the common voltage transfer pads 14 may be all the same or may be different voltages.

3, a conductive spacer 30 for electrically connecting the common voltage transfer wiring 14 of the TFT substrate 10 and the common electrode 24 of the color filter substrate 20 will be described. Explain.

The TFT substrate 10 and the color filter substrate 20 face each other with the liquid crystal layer 40 interposed therebetween, and the common voltage transfer pad 14 and the common electrode 24, which face each other, are formed of a conductive metal. Electrically connect using the conductive spacer 30.

In this case, an alignment layer may be formed under the common electrode 24.

The conductive spacer 30 is preferably a ball spacer, and gold (Au) or silver (Ag) may be utilized. In addition, the conductive spacer 30 is preferably mixed with the sealant composition 32 to fix the position.

4A and 4B are views for explaining a liquid crystal display device according to a first embodiment of the present invention in more detail. Particularly, FIG. 4A is a plan view of the TFT substrate 10 and FIG. 4B is a view of the color filter substrate 20. Top view.

Referring to FIG. 4A, a display area DA in which a plurality of data lines and gate lines are formed, and a plurality of liquid crystal pixels (not shown) including thin film transistors connected to the data lines and gate lines, and dummy lines or driving lines are formed. A plurality of common voltage transfer pads 14 are preferably formed in the non-display area NDA on the first substrate 12 divided into the non-display area NDA in which a driver or the like may be mounted.

The common voltage transfer pad 14 is made of metal, but may be ITO, and the common voltage transfer pad 14 is applied with a common voltage output from an external circuit unit (not shown). In this case, all of the common voltages applied to the common voltage transfer pads 14 may be the same or different voltages.

In addition, the common voltage transfer pad 14 is preferably configured at both ends of the display area DA, respectively, so as to be electrically connected to each other through a connection line 16. A description will be given together with the description of the substrate 20. In this case, the connection line 16 may be formed through the display area DA as shown, and may also be formed as a path covering the display area DA.

Although not shown on the second substrate 22, the color filter substrate 20 illustrated in FIG. 4B includes a black matrix BM and a color filter C / F. A plurality of common electrode 24 having a bar shape is formed. Each of the common electrodes 24 is an electrode for forming an electric field between pixel electrodes of liquid crystal pixels formed on the TFT substrate 10 by applying a common voltage. In the present invention, the common electrodes 24 are connected to the horizontal pixel rows of the TFT substrate 10. Each of the corresponding positions is formed to be parallel to each other, and formed on the upper layer of the color filter (C / F) and the black matrix (BM), but both are formed on the same layer.

In addition, the dotted line box 26 shows the position connected to the conductive spacer (30 in FIG. 3) when the TFT substrate 10 and the liquid crystal are opposed to each other, and the conductive spacer (30 in FIG. 3). Each of the common electrodes 24 is electrically connected to a common voltage transfer pad (16 in FIG. 4A) of the TFT substrate 10.

In addition, the common electrode 24 having a bar shape may be attenuated while the common voltage applied to one end is transferred to the other end by a load thereof, and thus, the common electrode 24 may be attenuated at two or more places including both ends as shown. The connection with the common voltage transfer pad 14 reduces the common voltage. Accordingly, the TFT substrate 10 may also be configured to have a common voltage transfer pad 14 electrically connected to one common electrode 24 at both ends of the display area DA.

According to the liquid crystal display device according to the first embodiment of the present invention having the features of the above-described configuration and structure, a plurality of liquid crystal pixels are arranged in a matrix so that a plurality of horizontal pixel rows are defined in the TFT substrate. A conductive spacer is formed by forming a common voltage transfer pad 14 and forming a plurality of bar-type separated and parallel common electrodes 24 on the color filter substrate at positions corresponding to the horizontal pixel rows. By performing electrical connection to 30, different common voltages may be applied to each horizontal pixel column.

Therefore, the common voltage inversion driving can be performed in the liquid crystal display device that forms the vertical electric field like the TN or VA mode liquid crystal display device as in the transverse electric field type liquid crystal display device, thereby reducing the power consumption for applying the common voltage. Will be provided.

Second Embodiment

FIG. 5 is a perspective view briefly illustrating a liquid crystal display according to a second exemplary embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 5, wherein the TFT substrate 50, the color filter substrate 60, and the conductive layer are conductive. A sealant composition 32 including a spacer (70 in FIG. 6) is shown.

In the following description of the second embodiment of the present invention, there is provided a configuration of the common voltage supply unit 90 together with the same components as the first embodiment.

In the configuration, the TFT substrate 50 and the color filter substrate 60 face each other, and a plurality of common voltage transfer pads 54 are formed on the TFT substrate 50. In addition, the color filter substrate 60 is provided with a bar-shaped common electrode 64 separated from each other at positions corresponding to the positions of the common voltage transfer pad 54, and the common voltage transfer pad 54. ) And a common conductive spacer 70 in the form of a ball is formed between the common electrode 64 and the common electrode 64 to electrically connect the common voltage transfer pad 54 and the common electrode 64. As shown in the cross-sectional view of FIG. 6, the conductive spacer 70 may be mixed with the sealant composition 72.

In addition, the TFT substrate 50 is provided with a common voltage supply unit 90 for applying a common voltage to each of the common voltage transfer pads 54 connected in pairs.

Accordingly, the common voltages respectively applied from the common voltage supply unit 90 to the plurality of common voltage transfer pads 54 are applied to the common electrodes 64 at opposite positions through the conductive spacers 70. In this case, all of the common voltages applied to the common voltage transfer pads 54 may be the same, or different voltages may be output and supplied for each common voltage supply unit 90.

6, a conductive spacer 70 for electrically connecting the common voltage transfer pad 54 of the TFT substrate 50 to the common electrode 64 of the color filter substrate 60 is further described. Explain.

The TFT substrate 50 and the color filter substrate 60 face each other with the liquid crystal layer 80 interposed therebetween, and the common voltage transfer pad 54 and the common electrode 64 which face each other also have a conductive metal. Electrically connect using the conductive spacer 70. In this case, an alignment layer may be formed under the common electrode 24.

In addition, the conductive spacer 30 is preferably a ball spacer, a gold (Au) or silver (Ag) is available. In addition, the conductive spacer 70 is preferably configured by mixing with the sealant composition 72 for fixing the position.

7A and 7B are views for explaining a liquid crystal display device according to a second embodiment of the present invention in more detail. In particular, FIG. 7A is a plan view of the TFT substrate 50 and FIG. 7B is a view of the color filter substrate 60. Top view.

Referring to FIG. 7A, a display area DA in which a plurality of data lines and gate lines are formed, and a plurality of liquid crystal pixels (not shown) including thin film transistors connected to the data lines and gate lines, and a dummy line or Preferably, a plurality of common voltage transfer pads 54 are formed in the non-display area NDA on the first substrate 52 divided into the non-display area NDA in which a driving driver or the like may be mounted.

The common voltage transfer pad 54 may be formed of metal, but may be ITO, and the common voltage transfer pad 54 may receive a common voltage output from the common voltage supply unit 90. In this case, the common voltage applied to each common voltage transfer pad 54 depends on the voltage output from the common voltage supply unit 90. In this case, a plurality of common voltage supply units 90 are configured and all common voltage output units ( In 90, the same common voltage may be output or different voltages may be output.

In addition, the common voltage transfer pad 54 is preferably configured at both ends of the display area DA, respectively, so as to be electrically connected to each other through a connection line 56, and thus, the common voltage supply unit 90. ) Is configured between two common voltage transfer pads 54 connected to each other through the connection wiring 56 to simultaneously supply the same common voltage to the two common voltage transfer pads 54 connected to each other. Of course, the common voltage supply unit 90 is also preferably configured in the non-display area (NDA).

As shown in the drawing, the connection line 56 may be formed through the display area DA, and may also be formed as a path covering the display area DA.

Here, the common voltage supply unit 90 is to improve the common voltage potential reduction problem, which is a disadvantage of the liquid crystal display according to the first embodiment described above, and all common voltages applied from the external circuit unit as in the first embodiment are all common. When applied to the voltage transfer pad 54 and supplied to the common electrode 64 of the color filter filter substrate 60, the load component included in the connection wiring 56, the conductive spacer 70, the common electrode 64, and the like. The potential may be reduced by supplying a common voltage separately for each common voltage transfer pad 54. Thus, since the supply path is significantly reduced compared to that supplied from an external circuit unit, the common voltage transfer pad ( Up to 54, the common voltage potential attenuation occurring during the transmission of the common voltage is also significantly reduced.

The common voltage supply unit 90, which provides such an advantage, is mounted on the non-display area NDA in the form of an integrated circuit IC or is formed of a thin film transistor using polysilicon on the TFT substrate 50. Naturally, it may be manufactured together when forming a thin film transistor (TFT), and the selection thereof depends on the application of the user.

Although not shown on the second substrate 62, the color filter substrate 60 shown in FIG. 7B is formed with a black matrix BM and a color filter C / F. A plurality of common electrodes 64 are formed. Each of the common electrodes 64 is an electrode for forming an electric field between pixel electrodes of liquid crystal pixels formed on the TFT substrate 50 by applying a common voltage. In the present invention, the common electrodes 64 are connected to the horizontal pixel rows of the TFT substrate 50. Each of the corresponding positions is formed to be parallel to each other, and formed on the upper layer of the color filter (C / F) and the black matrix (BM), but both are formed on the same layer.

In addition, the dotted line box 66 shows a position where the TFT substrate 50 is connected to the conductive spacer (70 in FIG. 6) when the TFT substrate 50 and the liquid crystal are interposed therebetween, and the conductive spacer (70 in FIG. 6). Each of the common electrodes 64 is electrically connected to a common voltage transfer pad (54 in FIG. 7A) of the TFT substrate 50.

In addition, since the common electrode 64 having a bar shape may be attenuated while the common voltage applied to one end is transferred to the other end by its load, the common electrode 64 may be attenuated at two or more places including both ends as shown. Performing a connection with the common voltage transfer pad 54 reduces the reduction of the common voltage. Therefore, it is preferable that the common substrate 54 is also electrically connected to one common electrode 54 in the TFT substrate 50 at both ends of the display area DA.

According to the liquid crystal display device according to the second embodiment of the present invention having the features of the above-described configuration and structure, a plurality of liquid crystal pixels are arranged in a matrix so that a plurality of horizontal pixel rows are defined in the liquid crystal display device. A conductive spacer is formed by forming a common voltage transfer pad 54 and forming a plurality of bar-type separated and parallel common electrodes 64 on a color filter substrate at a position corresponding to each horizontal pixel column. By performing electrical connection to 70, a different common voltage can be applied to each horizontal pixel column. In addition, a common voltage is supplied to each common electrode 64, but a plurality of common voltage supply sources (ie, the common voltage supply unit 90) are provided to improve common voltage attenuation, thereby providing a stable common voltage supply and high quality. Has the advantage of ensuring the display quality.

 In addition, the common voltage inversion driving can be performed in the same liquid crystal display device that forms a vertical electric field as in the TN or VA mode liquid crystal display device, thereby reducing the power consumption for applying the common voltage. It is natural to be offered.

As described above, the liquid crystal display device according to the first and second embodiments of the present invention can perform common voltage inversion even in a TN mode or a VA mode liquid crystal display device forming a vertical electric field, thereby reducing power consumption. In addition, by adding a separate common voltage supply unit, there is an advantage in that the power consumption can be reduced and a stable common voltage can be supplied.

Claims (16)

A first substrate having a plurality of liquid crystal pixels and a plurality of common voltage transfer pads to which a common voltage is applied; A second substrate on which a plurality of common electrodes are formed; A liquid crystal layer formed between the first substrate and the second substrate; A plurality of conductive spacers disposed between the first substrate and the second substrate and electrically connected to each of the plurality of common voltage transfer pads and the plurality of common electrodes; And a plurality of common electrodes each having two or more ends thereof connected to a common voltage transfer pad. The method according to claim 1, The plurality of liquid crystal pixels are formed in a display area, and the plurality of common voltage transfer pads are formed in a non-display area around the display area. The method according to claim 1, The plurality of common electrodes are all formed in the form of a bar (bar) liquid crystal display device The method according to claim 1, The plurality of common electrodes may be formed in parallel to each other. The method according to claim 1, Each of the plurality of common electrodes is connected to the common voltage transfer pad using at least one conductive spacer. The method according to claim 1, The plurality of common electrodes may be formed to correspond to the horizontal pixel rows of the first substrate. The method according to claim 1, The common voltage transfer pad is a liquid crystal display device, characterized in that the metal or ITO The method according to claim 1, A common voltage applied to the plurality of common voltage transfer pads is characterized in that the potential thereof changes every frame display period. The method according to claim 1, A plurality of common voltage supply units supplying a common voltage to each of the plurality of common voltage transfer pads A liquid crystal display device delete The method according to claim 9, The plurality of common voltage supply units may be integrated circuits or circuits composed of polysilicon thin film transistors. The method according to claim 1, The conductive spacer is a liquid crystal display device, characterized in that the metal ball (ball) spacer The method according to claim 1, The conductive spacer is a liquid crystal display device, characterized in that the spacer formed of gold or silver The method according to claim 1, The conductive spacer is included in the sealant composition, characterized in that the liquid crystal display device The method according to claim 1, The first substrate may further include a plurality of liquid crystal pixels including a plurality of data lines and gate lines and including a thin film transistor connected to the data lines and gate lines, and the second substrate may further include a color filter and a black matrix. Liquid crystal display device characterized in that The method according to claim 1, Liquid crystal display device characterized in that the plurality of common electrodes are all formed on the same layer

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