JP2004046249A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of achieving high luminance, high contrast ratio and high quality image display by simultaneously increasing the open area ratio of pixel parts and upgrading display quality. <P>SOLUTION: In the liquid crystal display, auxiliary capacitance lines 103 are arranged in such a way that they overlap pixel electrodes 105 at both ends of the pixel electrodes, and auxiliary capacitance (Cs) 106 is disposed in the space between pixels, that is, a so-called non-pixel part. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a liquid crystal display device, and particularly to an active matrix type liquid crystal display device having a high aperture ratio of a pixel portion.

(4) Liquid crystal display devices are actively used as display elements such as televisions and graphic displays, taking advantage of features such as thinness and low power consumption.

Among them, an active matrix type liquid crystal display device using a thin film transistor (hereinafter abbreviated as TFT) as a switching element is excellent in high-speed response, suitable for high definition, high image quality of a display screen, large size. And color imaging are attracting attention.

The display element portion of this active matrix type liquid crystal display device is generally provided with an active element array substrate on which a switching active element such as a TFT and a pixel electrode connected thereto are disposed, and an active element array substrate opposed thereto. The main part is composed of a counter substrate on which counter electrodes are formed, a liquid crystal composition sandwiched between these substrates, and a polarizing plate stuck on the outer surface side of each substrate.

In such an active matrix type liquid crystal display device, a liquid crystal pixel cell is formed for each pixel by a pixel electrode, a counter electrode, and a liquid crystal layer sandwiched between these electrodes.

(4) By changing the voltage applied to the pixel electrode, the optical state of the liquid crystal molecules of the liquid crystal pixel cell is changed to display an image on a screen. An electric field corresponding to a video signal voltage is not applied to a liquid crystal layer existing in a so-called non-pixel portion outside a pixel electrode. Therefore, these non-pixel regions are optically shielded.

(4) As described above, by changing the electric field of the pixel portion where the pixel electrode is formed, the optical state of the liquid crystal layer of the pixel portion is changed to perform display.

In the liquid crystal layer, the liquid crystal molecules of the part involved in display sandwiched between the pixel electrode and the counter electrode theoretically receive only the electric field applied from the pixel electrode as described above, and are in an optical state. Should change.

However, such a liquid crystal pixel cell for each pixel is actually affected by an electric field generated between the pixel electrode and a signal line or a scanning line disposed around the pixel electrode. There is a problem that a so-called edge reverse phenomenon occurs in which liquid crystal molecules in the vicinity are inverted.

That is, the liquid crystal molecules existing near the peripheral portion of the pixel electrode (that is, the peripheral portion of each pixel portion) have an electric field precisely corresponding to the video signal voltage applied from the pixel electrode in response to the video signal. In addition, since an image is affected by an electric field generated between the signal line and the scanning line, the optical state does not accurately correspond to a video signal when an image is displayed. For this reason, there is a problem that the contrast is reduced due to light leakage at the peripheral portion of the pixel portion, and the display quality of the screen is significantly reduced.

In order to prevent a decrease in contrast due to a phenomenon such as light leakage at the peripheral portion of the pixel portion, as shown in FIG. A gap of about several μm is provided between the scanning line 3 and the pixel electrode 1, and a black matrix 4 is formed outside the pixel electrode 1, that is, in a non-pixel region and a region where edge reverse occurs, so as to overlap. , Has been proposed. The black matrix 4 optically shields an area that does not accurately function as an optical shutter, thereby improving the display quality of the screen.

However, the black matrix 4 formed for the purpose of improving the display quality also has another aspect that the light use efficiency of the display device is reduced by increasing the light shielding area. Therefore, increasing the area of the black matrix 4 tends to increase the overall power consumption of the liquid crystal display device. Therefore, in order to simultaneously improve the display quality and the light use efficiency, while increasing the effective area of the pixel electrode 1 for driving (controlling) each liquid crystal pixel cell, the light shielding area is ensured while securing a sufficient light shielding effect. Needs to be small. In this way, it is necessary to increase the aperture ratio of the pixel portion as much as possible.

(4) As one of the measures for improving the aperture ratio of the pixel portion, a method has been proposed in which two adjacent storage capacitor lines are shared by one storage capacitor line 5. FIG. 11 is a diagram showing an outline of such a conventional liquid crystal display device, and FIG. 12 is an equivalent circuit diagram thereof.

As a result, the total number of wirings in the direction parallel to the scanning lines 3 in the display area, that is, the total number of the scanning lines 3 and the auxiliary capacitance lines 5 is 3/4 of that in the liquid crystal display device shown in FIG. The aperture ratio can be improved.

However, even in the above configuration, in order to avoid the influence of the electric field generated between the pixel electrode 1 and the scanning lines 3 and the signal lines 2 around the pixel electrode 1, especially between the pixel electrode 1 and the scanning line 3. It is necessary to provide a certain interval. Further, since the scanning lines 3 are arranged so as to be adjacent to each other every two rows, it is necessary to avoid short-circuit failure and the like. In some cases, there is a problem that the aperture ratio of the pixel portion is reduced by the distance between the scanning lines 3.

As another measure for improving the aperture ratio of the pixel portion, a method has been proposed in which the auxiliary capacitance line 5 and the scanning line 3 are shared by one wiring 6, as shown in FIGS.

As a result, the total number of wirings in the scanning line direction (that is, the horizontal direction in FIG. 13) in the display area is の that of the conventional method, so that the aperture ratio of the pixel portion is further reduced as compared with the above-described liquid crystal display device. It is thought that it can be improved.

However, in the case of the above-described liquid crystal display device, the auxiliary capacitance Cs for one row attached to the wiring 6 all acts as a parasitic capacitance when a scanning pulse is applied. However, there is a problem that a practical switching speed for switching the driving of the pixel unit TFT element 7 as a pixel switching element for each row during the horizontal blanking period cannot be obtained.

Further, a scanning line 3 to which a sharp scanning pulse for repeating the ON / OFF operation of the pixel portion TFT element 7 is applied is disposed at the left and right ends of the pixel electrode 1 in FIG. The liquid crystal molecules (not shown) are likely to cause edge reverse due to the interaction between the electric field and the pixel electrode 1. Therefore, it is necessary to provide a certain interval between the scanning line 3 (also serving as the auxiliary capacitance line 5 as described above) and the pixel electrode 1, and it is not possible to make them closer to each other. Therefore, even when such a wiring 6 serving as both the scanning line 3 and the auxiliary capacitance line 5 is employed, the improvement of the aperture ratio has already reached its limit, and there is a problem that further improvement is difficult.

Further, since the scanning line 3 and the auxiliary capacitance line 5 are also used, the dual-purpose wiring 6 functions as the auxiliary capacitance Cs in a state where the OFF signal of the pixel TFT element 7 is applied to the wiring 6. Must-have.

For example, when a MOS-type capacitor formed of a semiconductor layer having the same polarity as that of the pixel portion TFT element 7 is used as the auxiliary capacitance Cs, a sufficient gate voltage cannot be secured by the OFF signal of the pixel TFT element 7, so that the insulating capacity is not increased. It is difficult to form an inversion layer at the interface between the film and the semiconductor layer, and it becomes impossible to make this MOS type capacitor function effectively. Therefore, in a conventional liquid crystal display device having a structure as shown in FIG. 11, a MOS-type capacitor which requires application of a driving voltage cannot be used. Therefore, there is a problem that the capacity of another material and structure must be adopted, and the structure and the manufacturing process are greatly complicated.

Furthermore, as a problem common to the above three conventional liquid crystal display devices, there is a problem that when designing a black matrix, it is necessary to design in consideration of various precisions in each step.

In particular, in the case of a liquid crystal display device in which a black matrix is formed on a counter substrate, it is necessary to consider not only the processing accuracy of the black matrix but also the alignment accuracy of the active element array substrate and the counter substrate in the cell manufacturing process. The black matrix must be designed by expanding the area in advance from the minimum required area in consideration of a margin in which an error is considered. As a result, there is a problem that the aperture ratio of the liquid crystal display device is unnecessarily reduced.

The present invention has been made in order to solve such a problem, and an object of the present invention is to achieve high luminance, high contrast ratio, and high quality by simultaneously improving the aperture ratio of the pixel portion and the display quality. It is an object of the present invention to provide a liquid crystal display device capable of realizing an image display.

The liquid crystal display device of the present invention includes a plurality of rows of scanning wirings and a plurality of columns of signal wirings arranged so as to intersect with each other on a substrate, switching elements connected to the scanning wirings and the signal wirings, and each of the switching elements. A switching element array substrate on which a connected pixel electrode and an auxiliary capacitor connected to an output terminal of the switching element are formed; and a counter electrode disposed to face the switching element array substrate with a gap therebetween. And a liquid crystal composition sealed between the switching element array substrate and the counter substrate, wherein the scanning line is formed at a position crossing the pixel electrode, The capacitor has an electrode layer connected to the output terminal of the switching element, and an electrode layer facing the electrode layer via an insulating layer and the same layer as the scanning wiring. The storage capacitor line is formed at a portion opposing a storage capacitor line disposed along the scanning line, and the storage capacitor line is arranged in a row along the signal line and overlaps with one side of each of the pixel electrodes adjacent to each other. By doing so, the gap between the adjacent pixel electrodes is shielded from light.

In addition, in the above liquid crystal display device, the switching element is formed at a planar position overlapping with the signal wiring via an insulating layer.

In addition, in the above liquid crystal display device, a row of the scanning wiring connected to the switching element and a row of the pixel electrode connected to the switching element are different rows.

Further, in the liquid crystal display device according to any one of the above, the signal wiring is formed to face an end of the pixel electrode including a side in a direction parallel to the signal wiring via an insulating layer. It is characterized by:

The liquid crystal display device according to any one of the above, further comprising a liquid crystal drive circuit connected to the scanning wiring and the signal wiring and switching and writing the polarity of a video signal voltage for each pixel electrode for each row or each pixel electrode. It is characterized by doing.

(Function) According to the present invention, the auxiliary capacitance line is formed so as to partially overlap with the end of the pixel electrode, and this can be used as a part of the black matrix. Can reduce the decrease in the aperture ratio of the pixel portion due to the misalignment.

In addition, the posture of the liquid crystal molecules at the peripheral portion (peripheral edge portion) of the generally rectangular pixel electrode can be maintained in a stable state at a constant potential by the auxiliary capacitance line, resulting in the occurrence of edge reverse. This can prevent the display quality from deteriorating.

In addition, by arranging a pixel-port switching element, for example, a p-SiTFT or an a-SiTFT so as to block light with a signal wiring, it is possible to eliminate adverse effects such as light leakage caused by light incident on the switching element. Can be. In addition, it is possible to prevent the switching element from protruding into the pixel opening, and it is possible to further improve the pixel opening ratio.

In addition, by setting the row of the scanning line connected to the switching element and the row of the pixel electrode connected to the switching element to different rows, the pixel electrode being written and the scanning line being operated overlap. Thus, it is possible to avoid the state of being a single wiring, prevent the generation of a punch-through voltage due to the driving of the scanning line, and realize an improvement in display quality and an improvement in reliability.

In addition, by using the signal wiring as part of the black matrix, it is possible to prevent a decrease in the aperture ratio of the pixel area due to misalignment in the array process and the cell process, and to function as a black matrix with the signal wiring and auxiliary capacitance lines. Can be achieved, and it is not necessary to newly form a light shielding layer. Therefore, the manufacturing process of the liquid crystal display device can be greatly simplified.

In addition, when supplying a video signal to the pixels in the display area, by switching the polarity in units of rows or dots and supplying a signal, the potential of the signal wiring in the display area is averaged over one field period to assist. It is possible to maintain the same potential as the potential of the capacitor line or the potential of the counter substrate. Therefore, the potential of each wiring group in the display area becomes constant on average in one field period, and the occurrence of edge reverse and crosstalk can be prevented, so that the display quality of the liquid crystal display device can be greatly improved.

According to the present invention, it is possible to provide a liquid crystal display device capable of realizing a high-luminance, high-contrast ratio, and high-quality image display while achieving both an improvement in the aperture ratio of the pixel portion and an improvement in the display quality.

Hereinafter, embodiments of the liquid crystal display device of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a view mainly showing a pixel portion of a liquid crystal display device according to a first embodiment of the present invention. In each of the following drawings, a pixel opening is indicated by a bold line for the purpose of simplifying the illustration. Further, a portion where the scanning line 102 overlaps with the pixel electrode 105 and an auxiliary capacitance line 103 are shown with diagonal lines.

A signal wiring 101, a scanning wiring 102, and an auxiliary capacitance line 103 are arranged in a matrix. At each intersection of the signal wiring 101 and the scanning wiring 102, a TFT 104 as a switching element, a pixel electrode 105 connected to the TFT 104, and an auxiliary A capacitance (Cs) 106 is formed. The scanning lines 102 and the auxiliary capacitance lines 103 are alternately arranged from top to bottom in FIG. The upper and lower ends of the pixel electrode 105 are overlapped with the auxiliary capacitance line 103, and their respective parts are arranged so that the center thereof overlaps with the scanning wiring 102. This is a characteristic point of the structure of the liquid crystal display device of this embodiment.

FIG. 2 shows a cross section taken along line AA ′ of FIG. A liquid crystal 204 is sealed between a matrix substrate 201 made of a transparent insulating film and a counter substrate 203 on which a color filter 202 is formed to form a liquid crystal cell.

(4) On the matrix substrate 201, a TFT 104, an auxiliary capacitor 106, and the like are formed as pixel portion switching elements by using a low-temperature polysilicon process.

Next, a method of manufacturing the matrix array substrate 201 will be briefly described.

(4) An amorphous silicon thin film is formed on the transparent insulating substrate 205 by a plasma CVD method, patterned, and then recrystallized by excimer laser irradiation to obtain a polycrystalline silicon film 206.

Next, a silicon oxide film 207 for forming a gate insulating film and an insulating film of an auxiliary capacitor is formed by using a normal pressure CVD method.

Next, a Mo (molybdenum) -W (tungsten) thin film is formed by a sputtering method, and is patterned to obtain a gate electrode 208 of the TFT 104 and an upper electrode 209 of the storage capacitor (Cs) 106. The upper electrode 209 is shown as the upper electrode 209 in the cross-sectional view of FIG. 2 as a portion of the auxiliary capacitance line 103 that forms the auxiliary capacitance (Cs) 106 in particular.

Then, using the gate electrode 208 and the upper electrode 209 as a mask, impurities are added by an ion doping method to form a source region 210a and a drain region 210b of the TFT 104.

Then, an interlayer insulating film 211 is formed by a normal pressure CVD method, a contact hole is opened, and an aluminum film is formed by a sputtering method. Then, by patterning this aluminum film, a source electrode 212a and a drain electrode 212b are formed.

(4) After forming a second interlayer insulating film 213 and opening a contact hole, an ITO film is formed as a transparent conductive film, and the ITO film is patterned to form the pixel electrode 105.

It goes without saying that the method of manufacturing the TFT 104 as the pixel switching element is not limited to the above-described method of forming a p-Si TFT.

On the other hand, on the opposing substrate 203, an opposing electrode 215 made of a color filter 202, a black matrix 214, and a transparent conductive film is formed.

Further, a polyimide film is formed on the uppermost layer of both substrates to control the alignment direction of the liquid crystal, and an alignment process is performed on the surface thereof to form alignment films 216a and 216b. To form a liquid crystal cell.

In the above embodiment, the auxiliary capacitance 106 is of the MOS type. However, in order to set the potential of the auxiliary capacitance line 103 to an arbitrary potential, an impurity is implanted into the lower electrode 218 of the auxiliary capacitance 106 and the MIM type It is desirable to form the capacitor.

(4) The switching element has a structure for alleviating an electric field near the drain, for example, an LDD structure, so that a tunnel current near the drain can be suppressed and a leak current can be reduced.

As the impurity for forming the source region 210a / drain region 210b, an n-type impurity such as P (phosphorus) may be used, or a p-type impurity such as B (boron) may be used. Even if it is used, the same effect as the above embodiment can be obtained.

When a liquid crystal driver circuit (not shown) is integrally formed on the matrix array substrate 201, the liquid crystal driver circuit is configured as a CMOS structure, thereby realizing high-speed driving with low power consumption. Can be.

With the above structure, the auxiliary capacitance line 103 functions as a light shielding member for covering the non-pixel portion and the TFT 104 in addition to the black matrix 214. The portion in the same direction as above is not required. As a result, with respect to the direction parallel to the scanning wiring 102, the alignment accuracy in the cell assembling step, which is a problem when the black matrix 214 is formed on the counter substrate, and the case where the black matrix 214 is formed on the matrix array substrate 201 Since there is no need to consider the alignment accuracy between the black matrix 214 and each wiring, the processing accuracy of the black matrix 214 itself, and the like, the pixel portion aperture ratio can be significantly improved.

In the present embodiment, the auxiliary capacitance lines 103 are disposed so as to overlap each other at both ends of the pixel electrode 105, and the auxiliary capacitance (Cs) 106 is provided in a space between pixels, that is, in a so-called non-pixel portion. Even when the capacitance value of the auxiliary capacitance 106 has to be increased due to the change of the shape of the TFT 104 or the like, the influence on the pixel portion aperture ratio due to the increase in the capacitance value is small. It can be suppressed.

Further, in this embodiment, the auxiliary capacitance lines 103 are arranged so as to overlap with both ends of the pixel electrode 105, respectively, so that the state of the liquid crystal molecules existing in the regions at both ends of the pixel electrode 105 is assisted. It is possible to always maintain a stable state by the potential of the capacitor line 103. This makes it possible to eliminate the occurrence of edge reverse in the liquid crystal layer at the periphery of the pixel, as compared with the case where the scanning wiring 102 that repeats the ON / OFF operation of the TFT 104 is wired at the same position, and shields the edge reverse. The area of the black matrix 214 for the purpose of (1) can be omitted. As a result, the pixel unit aperture ratio and display quality can be significantly improved. This is most effective when the potential of the auxiliary capacitance line 103 is set to the same value as the central value of the positive and negative video signal amplitudes.

In addition, in this embodiment, the scanning wiring 102 has a structure in which it is electrically shielded from liquid crystal molecules by the pixel electrode 105. This makes it possible to prevent a change in the time constant of the scanning wiring 102 due to the influence of the dielectric constant of the liquid crystal molecules, thereby increasing the degree of freedom in designing and selecting the liquid crystal material, and adopting more optimal settings. There is also an advantage that you can do it.

Further, in this embodiment, the auxiliary capacitance line 103 and the scanning wiring 102 are formed independently, and the MOS-type capacitance element which cannot be used when the scanning wiring 102 and the auxiliary capacitance line 103 are shared is impossible. Is applied, so that the degree of freedom in designing the element structure is further increased as compared with a liquid crystal display device having a conventional configuration.

In this embodiment, the auxiliary capacitance 106 is formed by opposing the lower electrode 218 and the upper electrode 209 of the auxiliary capacitance line 103 via the silicon oxide film 207 as a dielectric layer. The upper and lower ends of the pixel electrode 105 in FIG. 1 and the upper electrode 209 of the auxiliary capacitance line 103 are opposed to each other via the interlayer insulating film 211 to form an electric capacitance. It has become part of the electrical capacity that helps. In this case, the auxiliary capacitance 106 is not limited to the case of this embodiment, for example, the lower electrode 218 is omitted, and the pixel electrode 105 and the upper electrode 209 of the auxiliary capacitance line 103 are interposed via the interlayer insulating film 211. Only the electric capacitance formed by facing the auxiliary capacitance line may be used as the auxiliary capacitance 106, or conversely, the pixel electrode 105 and the upper electrode 209 of the auxiliary capacitance line 103 are prevented from overlapping with each other. The upper electrode 209 and the lower electrode 218 may be formed so as to overlap each other, and only the electric capacitance formed by this may be used as the auxiliary capacitance 106.

As described in the above embodiment, the auxiliary capacitance lines 103 are arranged at both ends of the pixel electrode 105 in the direction along the signal wiring, and the portions function as a part of the light shielding film instead of the black matrix 214, By forming the scanning wiring 102 so as to overlap with the pixel electrode 105, the degree of freedom in design, process, design and selection of a liquid crystal material, etc., high display quality, large aperture ratio, and light utilization efficiency are improved. A liquid crystal display device with high power consumption and small power consumption can be obtained.

Note that the present invention is not limited to only the above embodiments. In addition, the auxiliary capacitance lines 103 are disposed so as to overlap the upper and lower ends of the pixel electrode 105, and the auxiliary capacitance lines 103 function as light shielding films in place of the black matrix 214 at those portions. Are arranged so as to cross the pixel electrode 105, the structure and the forming method of the TFT may be of any type, and any material may be used for each wiring material. good. Further, the channel portion of the TFT 104 may be made of amorphous Si, or may be formed of a material other than Si. An element other than the TFT may be used as the pixel switching element.

FIG. 3 is a view mainly showing a pixel portion of a liquid crystal display device according to a second embodiment of the present invention.

(3) By arranging the TFT 104 at a position overlapping with the signal wiring 101 as shown in FIG. 3, the signal wiring 101 can be used as a light shielding film of the TFT 104. In particular, generation of light leakage current of the TFT 104 due to light incident from a backlight or a projection light source can be eliminated.

Therefore, it is not necessary to increase the auxiliary capacitance 106 for the purpose of holding the video signal of the pixel electrode 105. As a result, it is possible to improve the aperture ratio of the pixel portion and the display quality of the screen.

FIG. 4 shows that the auxiliary capacitance line 103 also overlaps the upper and lower ends of the pixel electrode 105 below the signal line 101 in the liquid crystal display device of the second embodiment shown in FIG. FIG. 13 is a diagram showing a liquid crystal display device according to a third embodiment in which the aperture ratio is further improved by being arranged in a shape.

(4) As shown in FIG. 4, by forming the auxiliary capacitance line 103 below the signal wiring 101, a region where the auxiliary capacitance line 103 functions as a light shielding film like the black matrix 214 is expanded. In addition, since the auxiliary capacitance 106 can be formed in the lower layer of the signal wiring 101 in accordance therewith, the aperture ratio of the pixel portion can be further improved as compared with the second embodiment.

FIG. 5 is a diagram mainly showing a pixel portion of the liquid crystal display device of the fourth embodiment.

One terminal of the source / drain of the TFT 104 is connected to the signal line 101, and the other terminal passes through a lower layer of the auxiliary capacitance line 103 while forming the auxiliary capacitance 106, and is connected to a previous or next row. , Are connected to a pixel electrode 105 formed in a shape overlapping with the scanning wiring 102.

As shown in FIG. 5, by avoiding the overlap between the scanning wiring 102 for supplying a scanning pulse for controlling the TFT 104 and the pixel electrode 105 on which writing is performed, the scanning wiring 102 and the pixel electrode 105 are conventionally connected to each other. It is possible to suppress the generation of the punch-through voltage due to the parasitic capacitance formed therebetween. As a result, the writing error of the video signal can be eliminated, and the display quality can be improved.

FIG. 6 is a diagram mainly showing a pixel portion of the liquid crystal display device of the fifth embodiment.

The left and right ends in the drawing of the pixel electrode 105 are formed so as to overlap the signal wiring 101 via an insulating film (not shown), and the signal wiring 101 functions as a light shielding film instead of a black matrix. Can be.

The upper and lower ends of the pixel electrode 105 in the drawing are formed in the same structure as in the fifth embodiment and the like, and are shielded from light. Therefore, the black matrix 214 described in each of the above embodiments becomes completely unnecessary.

By adopting such a structure, the formation of the black matrix, which is essential in the conventional liquid crystal display device, becomes unnecessary, and the alignment accuracy in the cell process and the processing accuracy in the black matrix formation process are taken into consideration. Since the necessity is eliminated, the aperture ratio of the pixel portion can be further improved as compared with the conventional liquid crystal display device, and the display quality can be improved.

FIG. 7 is a diagram illustrating a liquid crystal display device according to a sixth embodiment in which the pixel electrodes 105 in the liquid crystal display device according to the fifth embodiment illustrated in FIG. 6 are arranged closer to the signal wiring 101. It is. By further reducing the area of the signal wiring 101 functioning as a black matrix, the aperture ratio of the pixel portion can be further improved as compared with the liquid crystal display device of the fifth embodiment.

FIG. 8 is a diagram showing a liquid crystal display device of a seventh embodiment in which the corner portion of the auxiliary capacitance line 103 is formed at an angle of 45 ° in the liquid crystal display device of the sixth embodiment shown in FIG. .

Thus, the loss area of the opening due to the auxiliary capacitance line 103 can be reduced without reducing the electric capacitance value of the auxiliary capacitance 106. That is, the area of the opening can be further increased, and the aperture ratio of the pixel portion can be further improved.

FIG. 9 is a diagram showing an example of a method for driving the liquid crystal display device according to the present invention.

As shown in the drawing, at the time of writing a video signal to the pixel electrode 105, the polarity of the video signal is inverted and supplied for each row or dot, so that the potential of the signal wiring 101 is averaged over one frame period. It is always located at the center of the drive amplitude of the video signal. Therefore, vertical crosstalk caused by the parasitic capacitance between the signal wiring 101 and the pixel electrode 105 can be suppressed, and the display quality of the liquid crystal display device can be significantly improved.

Note that the present invention is not limited to only the above embodiment, and both ends of the pixel electrode in a direction parallel to the signal wiring are formed so as to overlap with the auxiliary capacitance line via the insulating film, and the scanning wiring is If the pixel has a structure formed so as to overlap with the electrode, the aspect ratio of the pixel does not need to be 3: 1, and the same effect can be obtained even if the shape and interval of each wiring are different.

Further, particularly when the above-mentioned liquid crystal display device is used as a direct-view type display, further display is performed by shielding the wiring in the display area with a temporary reflection material typified by chromium oxide, a light absorbing black resin material, or the like. It is possible to improve the quality. In addition, the above-described low-reflection material has the same effect of preventing reflection of external light whether it is formed on the opposing substrate or the array substrate, and also on the matrix array substrate. For example, by forming the film through a back surface exposure step using each wiring in the display area as a mask, complication of the step accompanying the addition of the low reflection material can be prevented.

FIG. 3 is a diagram mainly showing a pixel portion of the liquid crystal display device of the first embodiment. FIG. 2 is a diagram showing a cross section taken along line AA ′ of FIG. 1. FIG. 9 is a diagram mainly showing a pixel portion of a liquid crystal display device of a second embodiment. FIG. 9 is a diagram illustrating a liquid crystal display device according to a third embodiment. FIG. 14 is a diagram mainly illustrating a pixel portion of a liquid crystal display device of a fourth embodiment. FIG. 14 is a diagram mainly illustrating a pixel portion of a liquid crystal display device according to a fifth embodiment. It is a figure showing the liquid crystal display of a 6th example. It is a figure showing the liquid crystal display of a 7th example. FIG. 4 is a diagram illustrating an example of a driving method of the liquid crystal display device according to the present invention. FIG. 11 is a diagram illustrating a conventional liquid crystal display device. FIG. 11 is a diagram illustrating a conventional liquid crystal display device. FIG. 10 is an equivalent circuit diagram of a conventional liquid crystal display device. FIG. 11 is a diagram illustrating a conventional liquid crystal display device. FIG. 10 is an equivalent circuit diagram of a conventional liquid crystal display device.

Explanation of reference numerals

101: signal wiring 102: scanning wiring 103: auxiliary capacitance line 104: TFT
105 pixel electrode 106 auxiliary capacitance (Cs)
214 Black matrix

Claims (5)

A plurality of rows of scanning lines and a plurality of columns of signal lines arranged so as to intersect with each other on a substrate, switching elements connected to the scanning lines and the signal lines, and pixel electrodes connected to the switching elements; A switching element array substrate on which an auxiliary capacitor connected to an output terminal of the switching element is formed; a counter substrate on which a counter electrode is disposed facing the switching element array substrate with a gap; A liquid crystal display device having a liquid crystal composition sealed between an array substrate and the counter substrate,
The scanning wiring is formed at a position crossing the pixel electrode,
The auxiliary capacitance is formed of an electrode layer connected to the output terminal of the switching element, and an auxiliary capacitance line opposed to the electrode layer via an insulating layer and arranged along the scanning wiring as the same layer as the scanning wiring. The storage capacitor lines are formed in opposing portions, and the storage capacitor lines are arranged in a row along the signal wiring and overlap with one side of each of the adjacent pixel electrodes to shield a gap between the adjacent pixel electrodes. A liquid crystal display device characterized by the above-mentioned. The liquid crystal display device according to claim 1, wherein the switching element is formed at a planar position overlapping the signal line via an insulating layer. 3. The liquid crystal display according to claim 1, wherein a row of scanning lines connected to the switching element and a row of pixel electrodes connected to the switching element are different rows. apparatus. 4. The liquid crystal display device according to claim 1, wherein the signal line faces an end of the pixel electrode including a side parallel to the signal line via an insulating layer. 5. A liquid crystal display device characterized by being formed. 5. The liquid crystal display device according to claim 1, wherein the liquid crystal is connected to the scanning wiring and the signal wiring, and writes by switching the polarity of a video signal voltage for each pixel electrode for each row or for each pixel electrode. A liquid crystal display device comprising a driving circuit.

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