CN101183196B - Pixel - Google Patents

Abstract

The present invention discloses a pixel suitable for being arranged between a first scanning line and a second scanning line of a multi-domain vertical alignment liquid crystal display panel. The pixel comprises a first active element, a second active element, a first pixel electrode, a second pixel electrode and a plurality of alignment components. The first active element is electrically connected to the first scanning line and a data line of the display panel, and the second active element is also electrically connected to the first scanning line and the data line. The first pixel electrode is electrically connected to the first active element, and the first pixel electrode covers a portion of the second scanning line to form a compensation capacitor. The second pixel electrode is electrically connected to the second active element, and there is a voltage difference between the second pixel electrode and the first pixel electrode. The plurality of alignment components are arranged on the first pixel electrode and the second pixel electrode.

Description

pixel

technical field

The present invention relates to a pixel structure of a liquid crystal display panel, and in particular to a pixel of a multi-domain vertical alignment (MVA) liquid crystal display panel.

Background technique

Existing liquid crystal displays tend to develop towards high brightness, high contrast, large area display and wide viewing angle. In order to improve the viewing angle of liquid crystal displays, various wide viewing angle technologies have been proposed. Wide-viewing-angle liquid crystal displays are currently common such as multi-domain vertical alignment liquid crystal displays, in-plane switching (IPS) liquid crystal displays, fringe field switching (FFS) liquid crystal displays, and the like.

FIG. 1 is a schematic top view of a conventional pixel applied to a multi-domain vertical alignment liquid crystal display. Please refer to FIG. 1, the pixel 100 is disposed on a thin film transistor array substrate (thin film transistor array substrate, TFT array substrate), the pixel 100 includes a scan line (scan line) 110, a data line (data line) 120, a thin film A transistor (thin film transistor, TFT) 130 , a pixel electrode (pixel electrode) 140 and a protrusion (protrusion) 150 . The thin film transistor 130 includes a gate 132 , a semiconductor layer 134 , a source 136 a , a drain 136 b and a contact window 138 . The gate 132 is electrically connected to the scan line 110 , and the semiconductor layer 134 is disposed above the gate 132 . The source electrode 136 a and the drain electrode 136 b are disposed on the semiconductor layer 134 , wherein the source electrode 136 a is electrically connected to the data line 120 .

The pixel electrode 140 is electrically connected to the drain electrode 136 b through the contact window 138 . In addition, in order to achieve multi-domain vertical alignment of the liquid crystal molecules, the protrusion 150 is disposed on the pixel electrode 140, and a plurality of protrusions (not shown) are disposed on the opposite color filter substrate (not shown). not shown). Therefore, through the combination of the protrusions 150 and the protrusions, the liquid crystal molecules disposed between the thin film transistor array substrate and the color filter substrate can be tilted in multiple directions, thereby achieving the effect of wide viewing angle display.

Although the above-mentioned multi-domain vertical alignment liquid crystal display can increase the viewing angle range, when the viewing angle changes from 0 degrees to 90 degrees, the light transmittance (transmission) of the multi-domain vertical alignment liquid crystal display is relative to the gray scale (gray level) will have a different gamma curve. To put it simply, as the viewing angle changes, the degree of distortion of the color tone and brightness distribution of the picture provided by the multi-domain vertical alignment liquid crystal display will become more obvious.

Contents of the invention

In view of this, the object of the present invention is to provide a pixel to reduce the degree of distortion of hue and brightness distribution caused by the change of viewing angle.

In addition, another object of the present invention is to provide another pixel to improve display quality.

To achieve the above or other objectives, the present invention proposes a pixel, which is suitable for being disposed between a first scanning line and a second scanning line of an active element array substrate of a multi-domain vertical alignment liquid crystal display panel, And it is controlled by the first scanning line and a data line of the active element array substrate. The pixel includes a first active device, a second active device, a first pixel electrode, a second pixel electrode and a plurality of alignment units. The first active device is electrically connected to the first scan line and the data line, and the second active device is also electrically connected to the first scan line and the data line. The first pixel electrode is electrically connected to the first active device, and the first pixel electrode covers part of the second scan line to form a compensation capacitance. The second pixel electrode is electrically connected to the second active element, and there is a voltage difference between the second pixel electrode and the first pixel electrode. A plurality of alignment members are disposed on the first pixel electrode and the second pixel electrode.

In an embodiment of the present invention, the pixel further includes a common line disposed under the first pixel electrode and the second pixel electrode.

In an embodiment of the present invention, the channel aspect ratios of the first active device and the second active device may be the same.

In an embodiment of the present invention, the first active device and the second active device may have a common source.

In an embodiment of the present invention, the alignment members mentioned above may be protrusions or slits.

Based on the above, since the pixel of the present invention uses two pixel electrodes, and one of the pixel electrodes covers part of the scanning line to form a compensation capacitor, a voltage difference can be generated between the two pixel electrodes. The voltage difference can cause the liquid crystal molecules on the two pixel electrodes to have different inclination angles, thereby reducing the extent to which the gamma curve of the light transmittance of the multi-domain vertical alignment liquid crystal display panel changes with the viewing angle relative to the gray scale.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are exemplified below and described in detail with accompanying drawings.

Description of drawings

FIG. 1 is a schematic top view of a conventional pixel applied to a multi-domain vertical alignment liquid crystal display.

FIG. 2 is a schematic top view of a pixel according to an embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of the pixel shown in FIG. 2 .

FIG. 4A is a schematic waveform diagram of the first pixel electrode and the second pixel electrode shown in FIG. 2 in the case of positive charging.

FIG. 4B is a schematic waveform diagram of the first pixel electrode and the second pixel electrode shown in FIG. 2 in the case of negative polarity charging.

Detailed ways

FIG. 2 is a schematic top view of a pixel according to an embodiment of the present invention. Please refer to FIG. 2 , the pixel 200 of this embodiment is suitable to be arranged between a first scanning line 210 and a second scanning line 220 of an active element array substrate of a multi-domain vertical alignment type liquid crystal display panel, and is controlled by the active The device array substrate is controlled by a first scan line 210 and a data line 230 . The pixel 200 includes a first active device 240 , a second active device 250 , a first pixel electrode 260 , a second pixel electrode 270 and a plurality of alignment components 280 . Wherein, the first active device 240 is electrically connected to the first scan line 210 and the data line 230 , and the second active device 250 is also electrically connected to the first scan line 210 and the data line 230 . The first pixel electrode 260 is electrically connected to the first active device 240 , and the second pixel electrode 270 is electrically connected to the second active device 250 . In addition, the first pixel electrode 260 partially overlaps the second scan line 220 to form a compensation capacitor in the area A where the two overlap. A plurality of alignment members 280 are disposed on the first pixel electrode 260 and the second pixel electrode 270 .

In this embodiment, the first active element 240 and the second active element 250 are, for example, thin film transistors or other switching elements with three terminals. In addition, in order to make the flicker effect generated by the first pixel electrode 260 and the second pixel electrode 270 similar, preferably the electrical properties of the first active device 240 and the second active device 250 are the same. For example, when the first active device 240 and the second active device 250 are thin film transistors, their channel aspect ratios may be the same. As far as the present embodiment is concerned, the first active device 240 and the second active device 250 having the same electric property can charge the first pixel electrode 260 and the second pixel electrode 270 electrically connected thereto to the same potential at the same time. Due to the effect of the compensation capacitance formed by the overlapping area A, there is a voltage difference between the first pixel electrode 260 and the second pixel electrode 270 after the first pixel electrode 260 and the second pixel electrode 270 are charged.

In more detail, since there is a voltage difference between the first pixel electrode 260 and the second pixel electrode 270, the inclination angles of the liquid crystal molecules above the first pixel electrode 260 and the second pixel electrode 270 can be made different, so as to reduce the The degree to which the gamma curve of light transmittance versus gray scale changes with viewing angle. Therefore, the multi-domain vertical alignment liquid crystal display using the pixel 200 of this embodiment can provide better display quality.

In addition, in this embodiment, the pixel 200 further includes a common line 290 disposed under the first pixel electrode 260 and the second pixel electrode 270 to form a storage capacitor. In other words, the architecture of the storage capacitor disclosed in this embodiment is that the storage capacitor is formed on a common line (Cs on common). However, the present invention does not limit the structure of the storage capacitor to the fact that the storage capacitor is formed on a common line (Cs on common). In other embodiments, the structure of the storage capacitor can also be that the storage capacitor is formed on the scan line (Cs on gate). For example, it is formed by partially overlapping the second pixel electrode 270 with the second scan line 220 .

In this embodiment, the first active device 240 and the second active device 250 have a common source 245 . However, in another embodiment, the first active device 240 and the second active device 250 may also have independent sources. In addition, in this embodiment, the alignment member 280 is a protrusion, but in another embodiment, the alignment member 280 may also be a slit. The equivalent circuit diagram of this embodiment will be described below.

FIG. 3 is an equivalent circuit diagram of the pixel shown in FIG. 2 . Please refer to FIG. 3 , C _lc1 represents the first liquid crystal capacitance (liquid crystal capacitance) formed by the first pixel electrode 260 and the common electrode (not shown) on the opposite substrate, and C _st1 represents the liquid crystal capacitance formed by the first pixel electrode 260 and the common line. 290 forms the first storage capacitance (storage capacitance), C _add represents the compensation capacitance formed by the first pixel electrode 260 and the second scanning line 220, C _gd1 represents the compensation capacitance formed by the first active element 240 and the first scanning line 210 The formed first parasitic capacitance (parasitic capacitance), _Clc2 represents the second liquid crystal capacitance formed by the second pixel electrode 270 and the common electrode, and C _st2 represents the second storage capacity formed by the second pixel electrode 270 and the common line 290. Capacitors C _st2 and C _gd2 represent the second parasitic capacitance formed by the second active device 250 and the first scan line 210 . In order to have similar flicker effects generated by the first pixel electrode 260 and the second pixel electrode 270 , preferably the first active device 240 and the second active device 250 are electrically identical. In other words, the first parasitic capacitance C _gd1 and the second parasitic capacitance C _gd2 are preferably the same.

FIG. 4A is a schematic waveform diagram of the first pixel electrode and the second pixel electrode shown in FIG. 2 when they are positively charged, wherein the horizontal axis represents time, the vertical axis represents potential, and the scanning line adopts a three-level driving method. Please refer to FIG. 3 and FIG. 4A, in order that the flicker effect produced by the first pixel electrode 260 and the second pixel electrode 270 can be similar, the first active element 240 and the second active element 250 can be designed to be electrically identical, and C _add +C _lc1 +C _st1 =C _lc2 +C _st2 , so the feedthrough voltage ΔV _p of the first pixel electrode 260 and the second pixel electrode 270 will be the same, where ΔV _p =ΔV _p1 −ΔV _p2 . In this way, the flicker effect generated by the first pixel electrode 260 and the second pixel electrode 270 can be made the same.

In more detail, when the first pixel electrode 260 and the second pixel electrode 270 are charged with positive polarity, they are charged to the same potential within the same time. However, the potential of the second scan line 220 will increase at the time t, and the increased amount is generally referred to as a kick-back voltage (kick-back voltage) _Ve . The kickback voltage V _e increases the potential of the first pixel electrode 260 by ΔV through the compensation capacitor C _add , where ΔV=C _add *V _e /(C _st1 +C _lc1 +C _add +C _gd1 ). In this way, there is a voltage difference ΔV between the first pixel electrode 260 and the second pixel electrode 270 after time t, so that the inclination angles of the liquid crystal molecules above the first pixel electrode 260 and the second pixel electrode 270 are different. .

4B is a schematic waveform diagram of the first pixel electrode and the second pixel electrode shown in FIG. 2 in the case of negative polarity charging, wherein the horizontal axis represents time, the vertical axis represents potential, and the scanning line adopts a three-level driving method. Please refer to FIG. 3 and FIG. 4B, after the time t', there will be a voltage difference ΔV between the first pixel electrode 260 and the second pixel electrode 270, the principle of forming this voltage difference ΔV is the same as the voltage difference in FIG. 4A The principle of ΔV is the same and will not be repeated here. The feedback voltage ΔV _p in FIG. 4B =ΔV _p1 '+ΔV _p2 ', and the voltage difference between the first pixel electrode 260 and the second pixel electrode 270

ΔV=C _add *V _e /(C _st1 +C _lc1 +C _gd1 +C _add ).

It should be noted that although the present embodiment uses the three-level driving mode as an example for illustration, the scanning line in this embodiment also adopts the fourth-level driving mode or other driving modes.

To sum up, since the pixel of the present invention uses two pixel electrodes, and one of the pixel electrodes covers part of the scanning line to form a compensation capacitor, a voltage difference can be generated between the two pixel electrodes. The voltage difference can cause the liquid crystal molecules on the two pixel electrodes to have different inclination angles, thereby reducing the extent to which the gamma curve of the light transmittance of the multi-domain vertical alignment liquid crystal display panel changes with the viewing angle relative to the gray scale. Therefore, the multi-domain vertical alignment liquid crystal display adopting the pixel of the present invention can provide better display quality.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The protection scope of the invention should be defined by the claims.

Claims (5)

1. pixel, be suitable for being disposed between one first sweep trace and one second sweep trace of an active component array base board of a multi-field vertical assigned LCD panel, and controlled by this first sweep trace and a data line of this active component array base board, this pixel comprises:

One first active member electrically connects with this first sweep trace and this data line;

One second active member electrically connects with this first sweep trace and this data line;

One first pixel electrode electrically connects with this first active member, and this this second sweep trace of first pixel electrode cover part, to form a building-out capacitor;

One second pixel electrode electrically connects with this second active member, and has a voltage difference between this second pixel electrode and this first pixel electrode; And

A plurality of orientation members are disposed on this first pixel electrode and this second pixel electrode.

2. pixel as claimed in claim 1 is characterized in that, also comprises a bridging line, is disposed at this first pixel electrode and this second pixel electrode below.

3. pixel as claimed in claim 1, it is characterized in that, this first active member and this second active member are thin film transistor (TFT), and this first active member and this second active member have a passage respectively, and this first active member is identical with the length breadth ratio of the passage of this second active member.

4. pixel as claimed in claim 1, it is characterized in that, this first active member and this second active member are thin film transistor (TFT), and this first active member and this second active member have one source pole respectively, and the source electrode of this first active member and this second active member is a common-source.

5. pixel as claimed in claim 1 is characterized in that, those orientation members comprise protrusion or slit.

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