KR101469988B1 - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device is disclosed. A liquid crystal display device includes a first substrate and a second substrate facing each other; A plurality of pixel electrodes interposed between the first substrate and the second substrate; A plurality of common electrodes spaced apart from the pixel electrodes and forming an electric field with the pixel electrodes; A liquid crystal layer interposed between the first substrate and the second substrate; A common driver for applying first voltage signals to the common electrodes; And a power supply unit for applying a second voltage signal to the common electrodes.

Ferroelectric, liquid powder, ferroelectric, passive, matrix

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

The embodiment relates to a liquid crystal display device.

As information processing technology is developed, flat panel display devices such as LCD, PDP, and AMOLED are widely used.

In particular, a liquid crystal display device displays an image by forming an electric field, aligning the liquid crystal layer, and changing optical characteristics of the liquid crystal layer.

At this time, in driving a liquid crystal display device, an electric field formed by a high potential difference may be required.

Embodiments provide a liquid crystal display device capable of driving with a low voltage and reducing noise.

A liquid crystal display according to an embodiment includes a first substrate and a second substrate facing each other; A plurality of pixel electrodes interposed between the first substrate and the second substrate; A plurality of common electrodes spaced apart from the pixel electrodes and forming an electric field with the pixel electrodes; A liquid crystal layer interposed between the first substrate and the second substrate; A common driver for applying first voltage signals to the common electrodes; And a power supply unit for applying a second voltage signal to the common electrodes.

The liquid crystal display according to another embodiment includes first pixel electrodes arranged in a plurality of first pixel regions; Second pixel electrodes disposed in the plurality of second pixel regions; First common electrodes disposed in the first pixel regions and electrically connected to each other and facing the first pixel electrodes; Second common electrodes disposed in the second pixel regions and electrically connected to each other and facing the second pixel electrodes; A common driver for sequentially applying first voltage signals to the first common electrodes and the second common electrodes; And a power supply unit for applying a second voltage signal to the first common electrodes and the second common electrodes at the same time.

A liquid crystal display according to an embodiment includes a common driver for applying first voltage signals to common electrodes and a power supply unit for applying a second voltage signal.

Therefore, in the liquid crystal display according to the embodiment, when displaying one frame, the second voltage signal of high voltage is used in the reset period in which the optical characteristics of the entire liquid crystal layer are implemented in the same manner.

Also, the liquid crystal display according to the embodiment uses the first voltage signals of low voltage in the display period for displaying the image of the frame.

Therefore, the liquid crystal display according to the embodiment is driven by using a common driver driven at a low voltage.

Also, in the liquid crystal display device according to the embodiment, the first voltage signals of low voltage can be used in the display period, thereby reducing the noise.

In the description of the embodiments, each panel, member, portion, film, substrate, or electrode is formed "on" or "under" of each panel, member, Quot; on "and " under" encompass both being formed "directly" or "indirectly" In addition, the upper or lower reference of each component is described with reference to the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation and does not mean the size actually applied.

1 is an exploded perspective view showing a liquid crystal panel according to an embodiment. 2 is a circuit diagram showing a liquid crystal display according to an embodiment. 3 is a waveform diagram showing a first data signal, a reset voltage signal, and a common voltage signal.

1 to 3, the liquid crystal display includes a liquid crystal panel 100, a common IC 200, a power supply unit 300, and a segment IC 400.

1, the liquid crystal panel 100 includes data signals applied from the common IC 200 and the segment IC 400, a reset voltage signal RS, and common voltage signals CS1, CS2,. ..) to display an image. The liquid crystal panel 100 includes an upper substrate 110, a lower substrate 120, pixel electrodes 140, common electrodes 130, and a liquid crystal layer 150.

The upper substrate 110 is a glass substrate. The upper substrate 110 may include a black matrix pattern having openings and a color filter disposed in the openings.

The lower substrate 120 is disposed below the upper substrate 110. The lower substrate 120 is a glass substrate, and is opposed to and spaced from the upper substrate 110.

Pixel regions P11 to Pnm in the form of a matrix are defined in the upper substrate 110 and the lower substrate 120. [ The pixel regions P11 to Pnm are units in which the image is displayed on the liquid crystal panel 100. [

The pixel regions P11 to Pnm may be divided into a plurality of columns Col1 to Coln and a plurality of rows Row1 to Rowm.

The pixel electrodes 140 are arranged in the pixel regions P11, .., Pnm, respectively. The pixel electrodes 140 are disposed on the lower substrate 120. The pixel electrodes 140 receive the data signals from the Seg IC 400.

The pixel electrodes corresponding to the respective columns of the pixel electrodes 140 are electrically connected to each other.

For example, the pixel electrodes of the first column COL1 are all electrically connected, and the pixel electrodes of the second column COL2 are electrically connected to each other.

At this time, the pixel electrodes of the first row (Row1) and the pixel electrodes of the second row (Row2) are not electrically connected.

Accordingly, the pixel electrodes 140 receive the data signals for each column. For example, the first data signal DS1 is applied to the pixel electrodes of the first column COL1.

The common electrodes 130 are arranged in the pixel regions P11, ..., Pnm, respectively. The common electrodes 130 are disposed under the upper substrate 110. The common electrodes 130 receive the common voltage signals CS1, CS2, ... from the common IC 200 and receive the reset voltage signal RS from the power supply unit 300.

Common electrodes corresponding to each row among the common electrodes 130 are electrically connected to each other.

For example, the common electrodes of the first row (Row1) are all electrically connected, and similarly, the common electrodes of the second row (Row2) are all electrically connected.

At this time, common electrodes of the first row (Row1) and common electrodes of the second row (Row2) are selectively electrically connected.

Accordingly, the common electrodes 130 receive the common voltage signals CS1, CS2, ... for each row. For example, the first common voltage signal CS1 is applied to the common electrodes of the first row Row1, and the second common voltage signal CS2 is applied to the common electrodes of the second row Row2 do.

In addition, the reset voltage signal RS is applied to all the common electrodes 130.

The pixel electrodes 140 and the common electrodes 130 are transparent conductors. Examples of the materials used for the pixel electrodes 140 and the common electrodes 130 include indium tin oxide, indium zinc oxide, and the like. .

The liquid crystal layer 150 is interposed between the upper substrate 110 and the lower substrate 120. More specifically, the liquid crystal layer 150 is interposed between the common electrodes 130 and the pixel electrodes 140.

The optical characteristics of the liquid crystal layer 150 are changed by an electric field formed between the common electrode 130 and the pixel electrode 140.

For example, the optical characteristics of the liquid crystal layer 150 vary depending on the electric field of the critical value, and the optical properties of the liquid crystal layer 150 may not change below the electric field of the critical value.

For example, the liquid crystal layer 150 may be a ferroelectric liquid crystal (FLC) or a liquid crystal powder (LP).

For example, the liquid crystal layer 150 is changed in optical characteristics by an electric field caused by a potential difference of a high voltage (VH) or more.

The common IC 200 is mounted on the liquid crystal panel 100. More specifically, the common IC 200 is mounted on the lower surface of the upper substrate 110.

The common IC 200 applies common voltage signals CS1, CS2, ... to the common electrodes 130. [ The common IC 200 includes a common driver 210, first transistors T11, T12, ..., a second transistor T2, third transistors T31, T32, 220).

The common driver 210 applies common voltage signals CS1, CS2, ... to the common electrodes 130. [ The common driver 210 includes a plurality of common voltage generators 211, 212, ....

Each of the common voltage generators applies the respective common voltage signals to the common electrodes corresponding to the respective rows by the operation of the first transistors T11, T12, ....

For example, the first common voltage generator 211 applies the first common voltage signal CS1 to the common electrodes corresponding to the first row Row1.

The first transistors T11, T12, ... electrically couple the common voltage generating units 211, 212, ... and the common electrodes 130 to each other.

For example, the first transistor T11 selectively connects common voltages of the first common voltage generator 211 and the first row Row1.

The second transistor T2 electrically connects the common electrodes of the first row Row1 and the power supply unit 300 selectively.

The third transistors T31, T32, ... selectively and electrically connect the common electrodes corresponding to the respective rows.

For example, the first third transistor T31 selectively electrically connects common electrodes of the first row Row1 and common electrodes of the second row Row2.

Likewise, the second third transistor T32 selectively electrically connects the common electrodes of the second row Row2 and the common electrodes 130 of the third row.

The controller 220 controls the first transistors T11, T12, ..., the second transistor T2 and the third transistors T31, T32, ....

At this time, the controller 220 reversely operates the second transistor T2 and the third transistors T31, T32, ... with respect to the first transistors T11, T12, .

Also, the controller 220 operates the second transistor T2 and the third transistors T31, T32, ... in the same manner.

More specifically, when the control unit 220 turns on the first transistors T11, T12, ..., the second transistor T2 and the third transistors T31, T32, ... are turned on. . ≪ / RTI >

In addition, when the control unit 220 turns off the first transistors T11, T12, ..., the second transistor T2 and the third transistors T31, T32, ... are turned off. ).

The power supply unit 300 applies the reset voltage signal RS to the common electrodes 130 by the switching operation of the second transistor T2 and the third transistors T31, .

The Seg IC 400 applies the data signals to the pixel electrodes 140. At this time, the pixel electrodes corresponding to the respective columns are electrically connected to each other, and the segment IC 400 applies data signals to the pixel electrodes corresponding to the respective columns.

For example, the Seg IC 400 applies the first data signal DS1 to the pixel electrodes 140 of the first column COL1. Similarly, the Seg IC 400 applies a second data signal to the pixel electrodes 140 of the second column COL2.

Referring to FIG. 4, the data signals and the reset voltage signal RS include a reset period (RSP).

In the reset period RSP, the optical characteristics of the liquid crystal layer 150 disposed on the screen on which the image of the liquid crystal display device is displayed are the same.

That is, in the reset period RSP, the potential difference formed between the common electrodes 130 and the pixel electrodes 140 is all the same.

Accordingly, the same brightness can be realized over the entire screen.

In the reset period RSP, the data signals have a reference voltage, that is, a ground voltage VG.

On the other hand, in the reset period RSP, the reset voltage signal RS has a positive high voltage VH +.

That is, in the reset period RSP, a ground voltage VG is applied to all the pixel electrodes 140, and a positive high voltage VH + is applied to the common electrodes 130.

More specifically, the ground voltage VG is applied to the entire pixel electrodes 140 by the segment IC 400 in the reset period RSP.

In the reset period RSP, the first transistors T11, T12, ... are turned off and the second transistor T2 and the third transistors T31, T32, ... are turned off. Is turned on. Accordingly, the positive high voltage (VH +) is applied to the common electrodes by the power supply unit (300).

Accordingly, a potential difference of a high voltage (VH), which is a threshold voltage at which the optical characteristic of the liquid crystal layer 150 is changed, is formed between the pixel electrodes 140 and the common electrodes 130, (150) have the same optical characteristics.

Further, after the reset period RSP, the data signals and the common voltage signals CS1, CS2, ... have a display period.

During the display period, the first transistors T11, T12, ... are turned on and the second transistor T2 and the third transistors T31, T32, do.

Accordingly, the optical characteristics of the liquid crystal layer 150 are changed by the electric field formed by the data signals and the common voltage signals CS1, CS2,...

For example, a negative medium voltage VM- is applied to the common electrodes of the first row Row1 by the first common voltage signal CS1, The data signals are applied.

At this time, a part of the data signals has a medium voltage (VM +) of positive polarity, and a medium voltage (VM +) of positive polarity is applied to a part of the pixel electrodes 140. Also, the high voltage VH is twice the medium voltage VM.

A high voltage VH is applied between the pixel electrodes 140 and the corresponding common electrodes 130 to which a medium voltage VM + of positive polarity is applied among the pixel electrodes 140 of the first row Col1. And the optical characteristics of the liquid crystal layer 150 are changed.

For example, when a medium positive voltage VM + is applied to the pixel electrodes 140 of the first column COL1 and a negative medium voltage VM- is applied to the common electrodes of the first column Col1, Is applied.

At this time, a potential difference of a high voltage (VH) is formed between the first row (Row1), the pixel electrode (140) of the first column (COL1) and the common electrode (130). The optical characteristics of the liquid crystal layer 150 are changed in the pixel regions of the first row Row1 and the first column COL1 and the optical characteristics of the liquid crystal layer 150 are changed in the pixel regions of the first column Col1 and the first row Row1 The image is displayed.

Here, the high voltage VH may be at least two times the medium voltage VM.

When an image of one frame is displayed in this manner, the image of the next frame is displayed after resetting the screen with the reset period (RSP) in the next frame.

The high voltage VH is applied to the common electrode 130 by the power supply unit 300 only during the reset period RSP and the common IC 200 applies the high voltage VH to the common electrode 130 during the display period. A medium voltage VM- is applied.

Therefore, the common IC 200 can be driven at a low voltage (e.g., VM).

Therefore, the liquid crystal display according to the embodiment can reduce the noise generated when the common IC 200 is driven at a high voltage.

4 is an exploded perspective view illustrating a liquid crystal panel according to another embodiment. In this embodiment, the common electrodes and the pixel electrodes are further described with reference to the above-described embodiments.

Referring to FIG. 4, the pixel electrodes 140 extend in a first direction, and the common electrodes 130 extend in a second direction.

That is, in the embodiment described above, one common electrode and one pixel electrode, which are common electrodes of each row and common electrodes of each column, are integrally formed.

At this time, the pixel regions are defined corresponding to overlapping regions of the common electrodes 130 and the pixel electrodes 140.

In addition, the liquid crystal layer 150 is changed in optical characteristics by the electric field formed between the overlapping portions of the common electrodes 130 and the pixel electrodes 140, thereby displaying an image.

Since the common electrodes and the pixel electrodes do not need to be formed separately for each pixel region in this embodiment, the liquid crystal display according to the present embodiment can more easily form the common electrodes 130 and the pixel electrodes 140 can do.

In the liquid crystal display device according to the present embodiment, one common electrode is arranged corresponding to pixel regions of one row, and one pixel electrode is arranged corresponding to pixel regions of one column.

Accordingly, the liquid crystal display device according to the present embodiment can prevent a short circuit as compared with the case where the common electrodes and the pixel electrodes are formed separately for each pixel region.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

1 is an exploded perspective view showing a liquid crystal panel according to an embodiment.

2 is a circuit diagram showing a liquid crystal display according to an embodiment.

3 is a waveform diagram showing a first data signal, a reset voltage signal, and a common voltage signal.

4 is an exploded perspective view illustrating a liquid crystal panel according to another embodiment.

Claims (12)

A first substrate and a second substrate facing each other; A plurality of pixel electrodes interposed between the first substrate and the second substrate; A plurality of common electrodes spaced apart from the pixel electrodes and forming an electric field with the pixel electrodes; A liquid crystal layer interposed between the first substrate and the second substrate; A segment driver for applying data signals to the pixel electrodes; A common driver for applying first voltage signals to the common electrodes during a display period; And And a power supply for applying a second voltage signal to the common electrodes during a reset period, Wherein a potential difference between the data signal and the first voltage signal in the display period corresponds to a potential difference between the data signal in the reset period and the second voltage signal. The liquid crystal display according to claim 1, wherein the liquid crystal layer has an optical characteristic changed by an electric field exceeding a threshold value. The liquid crystal display of claim 1, further comprising switching elements for selectively electrically connecting the common electrodes and the power supply unit. The liquid crystal display of claim 1, wherein the second voltage signal is at least twice as large as the first voltage signal. The liquid crystal display according to claim 1, wherein the liquid crystal layer is interposed between the pixel electrodes and the common electrodes, The data signals are applied to the pixel electrodes to form the electric field, Wherein during the reset period the liquid crystal layer has the same optical properties Liquid crystal display device. The liquid crystal display of claim 1, wherein the pixel electrodes extend in a first direction, and the common electrodes intersect the pixel electrodes and extend in a second direction. The liquid crystal display of claim 1, wherein the first substrate and the second substrate define pixel regions in a matrix form, Wherein the pixel electrodes and the common electrodes correspond to the pixel regions, The pixel electrodes disposed in the respective columns are electrically connected to each other, And the common electrodes disposed in the respective rows are electrically connected to each other. First pixel electrodes disposed in a plurality of first pixel regions; Second pixel electrodes disposed in the plurality of second pixel regions; A segment driver for applying data signals to the pixel electrodes; First common electrodes disposed in the first pixel regions and electrically connected to each other and facing the first pixel electrodes; Second common electrodes disposed in the second pixel regions and electrically connected to each other and facing the second pixel electrodes; A common driver sequentially applying first voltage signals to the first common electrodes and the second common electrodes in a display period; And And a power supply for simultaneously applying a second voltage signal to the first common electrodes and the second common electrodes during a reset period, Wherein a potential difference between the data signal and the first voltage signal in the display period corresponds to a potential difference between the data signal in the reset period and the second voltage signal. The plasma display apparatus of claim 8, further comprising: a first switching device for selectively electrically connecting the first common electrodes and the common driver; And And a second switching element for selectively electrically connecting the second common electrodes and the common driver. The liquid crystal display of claim 9, further comprising a third switching device for selectively electrically connecting the first common electrodes and the power supply unit. The liquid crystal display of claim 10, further comprising a fourth switching device for selectively electrically connecting the first common electrodes and the second common electrodes. 12. The liquid crystal display of claim 11, further comprising a control unit for controlling the first switching device, the second switching device, the third switching device, and the fourth switching device.

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