JPH1048595A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] [Object] To provide a liquid crystal display device in which, when divided driving is performed, there is no display defect at a boundary and an entire screen is displayed uniformly. SOLUTION: The scanning direction is made different for each divided group,
In addition, each pixel electrode is arranged before the scanning line for switching the switching element connected to the pixel electrode in the scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device, and more particularly, to a scanning direction when divided driving is performed and an arrangement of pixel electrodes.

[0002]

2. Description of the Related Art Currently, liquid crystal display devices are being developed with a view to increasing their size. To increase the size of a liquid crystal display device, it is necessary to increase the number of scanning lines. However, if the number of scanning lines increases, the frequency of one frame decreases and flicker occurs, and the display contrast decreases. There is a problem.

Therefore, a technique is known in which the number of scanning lines is doubled without lowering the frequency of one frame by performing a so-called divided drive in which a screen is divided into upper and lower parts and driven independently of each other. Is being developed.

For example, as shown in FIG. 8, when each pixel electrode is arranged between the scanning line of the own stage and the scanning line of the next stage,
Each pixel electrode comes close to the next scanning line, and there is a problem that when a selection voltage is applied to the next scanning line, it is affected by the selection voltage and a display failure occurs. FIG. 9 shows a driving waveform of the scanning voltage. Specifically, for example, the pixel electrodes in the first row are affected by the selection voltage in the second row, and hold the voltage in the affected state for one frame. Further, the pixel electrode on the n / 2-th row is affected by the selection voltage on the n / 2 + 1-th row, but since the scanning line on the n / 2 + 1-th row belongs to the second group, the scanning on the n / 2-th row is performed. N / 2 + after a blanking period after the selection voltage is applied to the line
Since the selection voltage is applied to the first row, it is affected by a shift in timing as compared with the pixels in the other rows. As a result, there is a problem that only the pixel electrode in the n / 2-th row performs display different from that of the other pixels, and a linear defective display is performed when the entire screen is viewed.

When the pixel electrodes are arranged between the scanning line of the current stage and the scanning line of the preceding stage as shown in FIG. 10, each pixel electrode is separated from the scanning line of the next stage. It is not affected by the selection voltage applied to the scanning line.
(Depending on the selection voltage applied to the previous scanning line, in this case, it is immediately rewritten to the correct signal voltage,
In this state, there is no problem because it is held for one frame. However, there is a problem that the pixel electrode on the n / 2-th row in the same drawing is affected by the selection voltage applied to the (n / 2 + 1) -th scanning line and causes display failure.

As described above, when the division driving is performed, there is a problem that a difference in contrast is conspicuous at a boundary between the divisions. To solve this problem, Japanese Patent Laid-Open Publication No.
In Japanese Patent Application Laid-Open Publication No. H11-264, a method is disclosed in which an upper half screen and a lower half screen are respectively scanned toward the center, or are respectively scanned upward and downward from the center.

[0007]

However, even with the above-described method, the difference between the boundaries cannot be completely eliminated. that is,
Each pixel electrode is affected by the scanning voltage applied to the next scanning line, but only the pixel electrode at the boundary is different from the other pixel electrodes in the timing of the scanning voltage applied to the adjacent scanning line. It is. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a liquid crystal display device that can display a good image at a boundary even when divided driving is performed.

[0008]

The present invention comprises a first substrate,
An array substrate including: a plurality of scanning lines formed in parallel on the first substrate; a switching element that is switched by a scanning voltage applied to the scanning line; and a pixel electrode connected to the switching element. , A second substrate,
A counter substrate having a counter electrode formed on the second substrate; and a liquid crystal interposed between the array substrate and the counter substrate. The scanning lines are divided into n groups (m is 2
In a liquid crystal display device which is divided into the above natural numbers and is simultaneously scanned for each group, the k-th group (k = 1,
The scanning direction in (2,..., M-1) and the scanning direction in the (k + 1) th group are different, and among the two scanning lines sandwiching an arbitrary scanning line excluding the scanning lines at both ends in each group, A liquid crystal display device in which a capacitance formed between a pixel electrode switched by a switching element connected to an arbitrary scanning line is scanned from a larger scanning line to a smaller scanning line. It is.

Further, according to the present invention, a pixel electrode which is switched by a switching element connected to any one of the two scanning lines sandwiching an arbitrary scanning line except for the scanning lines at both ends in each group is provided. The liquid crystal display device is characterized in that scanning is performed from a scanning line having a short distance to a scanning line having a long distance. According to this configuration, it is possible to perform high-quality display without causing display unevenness in the pixel electrodes on the boundary of the division when performing the division driving.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing a pattern of the liquid crystal display device of the present embodiment. FIG. 2 is a sectional view showing one pixel. The configuration of the liquid crystal display device will be described with reference to FIG. On the array substrate 1, n scanning lines 4 are formed in a row direction, and a plurality of signal lines 5 are formed in a column direction so as to be orthogonal to the scanning lines 4. At each intersection of the scanning line 4 and the signal line 5, a thin film transistor 6 (TF
A thin film transistor (T: Thin Film Transistor) is formed, and a pixel electrode 7 is formed in connection with the TFT 6.

Next, referring to FIG. 2, the structure of the counter substrate 2 is such that a counter electrode 9 is formed on a glass substrate 8. The liquid crystal 10 is sandwiched between the array substrate 1 and the opposing substrate 2. Further, polarizing plates 11 and 12 are formed on the outer surfaces of the array substrate 1 and the counter substrate 2, respectively.

In this embodiment, the scanning line 4 performs a so-called two-division driving in which the upper half is a first group and the lower half is a second group, and each group is separately scanned. FIG. 3 shows a driving waveform of the scanning voltage in this embodiment. First
The group is scanned upward from the center of the screen, and the second group is scanned downward from the center of the screen. At this time, with respect to the first group of scanning lines 4, each pixel electrode 7
, And each pixel electrode 7 is arranged above the scanning line 4 in the second stage with respect to the second group of scanning lines 4. In other words, the pattern is symmetrical about the vertical center of the panel. Considering the respective scanning directions, each pixel electrode 7 is arranged before the scanning line 4 of the corresponding stage in the scanning direction with respect to any group of the scanning lines 4. (Here, the scanning line of the own stage is a scanning line for sending a scanning voltage to the TFT connected to the pixel electrode 7.) That is, an arbitrary scanning line among two scanning lines sandwiching the arbitrary scanning line The scanning is performed in a direction from the scanning line closer to the pixel electrode switched by the switching element connected to the line to the scanning line farther from the pixel electrode. Alternatively, scanning is performed in a direction from the larger scanning line to the smaller scanning line formed between the pixel electrode and the pixel electrode.

Here, in this embodiment, the pixel electrode is approximately square, one side is 100 μm, the scanning line width is 7 μm, and the width between the pixel electrode and the scanning line adjacent to the pixel electrode is 5 μm.
Therefore, the distance between any pixel electrode and the preceding scanning line is 5 μm.
m, on the other hand, the distance between this pixel electrode and the next scanning line is (the distance to the own scanning line + the own scanning line width + the distance to the next pixel electrode + the next pixel electrode) Width + distance to the next scanning line) = (5 μm + 7 μm + 5 μm + 100 μ)
(m + 5 μm) = 122 μm.

Further, regarding a capacitance formed between a pixel electrode and a scanning line, a capacitance C = εS / d (ε = dielectric constant, S
= Area, d = distance). S is an area where the cross section of the pixel electrode end face and the cross section of the scanning line end face each other.

Accordingly, the capacitance formed between an arbitrary pixel electrode and the preceding and next scanning lines is inversely proportional to the distance. Therefore, the capacitance formed between this pixel electrode and the preceding scanning line is Is larger than the capacitance formed between the pixel electrode and the next scanning line.

By arranging the pixel electrodes 7 and the scanning lines 4 in the above-described manner and in the scanning direction, it is possible to reduce a difference in the boundary at the center of the panel, which is a problem in the case of divided driving. Specifically, it is possible to reduce a display defect in which the n / 2-th row and the n / 2 + 1-th row shown in FIG. it can.

The operation of the embodiment of the present invention will be described.
In the present invention, since the pixel electrode 7 is arranged before the scanning line 4 of the own stage in the scanning direction, the distance from the next scanning line is increased. For example, n / 2 as an arbitrary scanning line
It is assumed that the first scanning line is a scanning line, and two scanning lines sandwiching an arbitrary scanning line are the n / 2-2 and n / 2 scanning lines. Considering the pixel electrode 7 switched by the switching element connected to the n / 2-1 row scanning line, the n / 2-2 row scanning line is the next scanning line, and n
The scanning line in the / 2 row is the preceding scanning line. As described above, the pixel electrode 7 is separated from the next scanning line by one pixel or more, so that the pixel electrode 7 is not affected by the selection voltage applied to the next scanning line. Conversely, since the distance from the preceding scanning line, that is, the scanning line 4 in the n / 2-th row is short, each pixel electrode 7 is affected by the selection voltage applied to the n / 2-th row. However, immediately after the selection voltage is applied to the preceding scanning line, the selection voltage is applied to the scanning line of the own stage, and the correct signal voltage is applied to each pixel electrode 7. Almost no problem. Here, the preceding scanning line is a scanning line to which the selection voltage is applied immediately before the selection voltage is applied to the own scanning line, that is, one scanning line in the scanning direction viewed from the own scanning line. This is the scanning line in front. The next scanning line is a scanning line to which the selection voltage is applied immediately after the selection voltage is applied to the scanning line of the own stage, that is, one scanning line in the scanning direction viewed from the scanning line of the own stage. This is the scanning line behind the book.

Further, in addition to the present embodiment, as shown in FIG. 4, the pixel electrode on the n / 2th row and the n
It is preferable that the dummy wiring 41 be provided between the pixel electrode of the (/ 2 + 1) th row and the pixel electrode of the other row since the appearance of the screen becomes the same as that of the other rows.

Further, as shown in FIG. 5, a modification of the pattern shown in FIG. In this case, the scanning direction of the first group is from the upper side of the screen, and the scanning direction of the second group is from the lower side of the screen.

Further, according to the present invention, as shown in FIG. 6, a metal-insulator-metal laminated MI is used as a switching element.
The present invention can also be applied to a liquid crystal display device using an M (Metal-Insulator-Metal) element. Figure 6 shows the MIM
This is an example in which two elements are used in series for one pixel. FIG.
(A) is AA ′ in FIG. 6, and (b) is B-B in FIG.
B ′ and FIG. 7C are cross-sectional views taken along CC ′ in FIG. FIG. 6 does not show the counter substrate.

A liquid crystal display device using this MIM element will be described with reference to FIGS. The array substrate has a first electrode 62 formed on a substrate 61 made of glass. Further, an insulator 63 is coated on the first electrode 62. A plurality of scanning lines 64 and a second electrode 65 protruding from the scanning lines 64 are formed in the row direction. Further, a third electrode 66 is formed on the insulator 63 so as not to contact the second electrode 65, and the third electrode is connected to the transparent pixel electrode 67.

The opposing substrate has a stripe-shaped opposing electrode 69 formed on a glass substrate 68 in a column direction with a width covering the pixel electrode. The liquid crystal 70 is sandwiched between the array substrate and the opposing substrate.

Further, the present invention can be applied to a liquid crystal display device in which the pixel electrode 7 overlaps the scanning line 4 as shown in FIG. In this case, when viewed two-dimensionally, at least half of the total area of each pixel electrode 7 is arranged before the scanning line of the own stage in the scanning direction. In this case, the front in the scanning direction is closer to the center of the width of the scanning line.

FIG. 9 shows an example of a configuration in which the pixel electrode 7 overlaps the scanning line 4 in this manner. The configuration of the array substrate 1 is such that a light shielding film 91 made of a-Si is formed on a glass substrate 3.
And an undercoat film 92 made of a silicon nitride film or the like.

Further, p-type
An Si layer is formed, and this p-Si layer is divided into a source region 93 (s), a drain region 93 (d), and a channel region (c). A gate insulating film 94 is covered so as to cover the p-Si layer. The gate insulating film 9
4, a gate electrode 95 made of molybdenum / tungsten or the like is formed in a region above the channel region 93 (c). Further, a first interlayer insulating film 96 made of a silicon oxide film or the like is covered so as to cover gate electrode 95.
Then, the source electrode 9 formed on the first interlayer insulating film
7 (s) and the drain electrode 97 (d)
4 and the first interlayer insulating film 96, the source region 93 (s) and the drain region 9 are respectively formed by through holes.
3 (d). Further, a second interlayer insulating film 98 made of an acrylic resin or the like is formed so as to cover them, and the pixel electrode 7 made of ITO formed thereon is formed.
Are connected to the source electrode 97 (s) by through holes formed in the second interlayer insulating film. An alignment film 99 made of polyimide or the like is formed on the uppermost layer.

On the other hand, the structure of the opposing substrate 2 is a glass substrate 8
A color filter 100, a counter electrode 9, and an alignment film 101 are provided thereon.
Are formed. The liquid crystal 10 is sandwiched between the array substrate 1 and the opposing substrate 2 to form a liquid crystal display device. With such a configuration, the pixel electrode 7 can overlap the scanning line 4, and the present invention can be applied to this case as well.

[0027]

According to the present invention, there is a problem of divided driving by dividing the scanning direction for each group by divided driving and arranging the pixel electrodes before the scanning line of the own stage in the scanning direction. It is possible to eliminate display defects at boundaries and to perform uniform display over the entire screen.

[Brief description of the drawings]

FIG. 1 is a plan view of a liquid crystal display device using a thin film transistor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a liquid crystal display device using a thin film transistor according to an embodiment of the present invention.

FIG. 3 is a driving waveform of a scanning voltage in the embodiment of the present invention.

FIG. 4 is an enlarged plan view of a vertical center portion of the liquid crystal display device according to the embodiment of the present invention.

FIG. 5 is a plan view of the liquid crystal display device according to the embodiment of the present invention.

FIG. 6 is a plan view of a liquid crystal display device using an MIM element according to an embodiment of the present invention.

FIG. 7A is a sectional view taken along line AA ′ in FIG. 6;
FIG. 7B is a cross-sectional view taken along the line BB ′ in FIG. 6, and FIG. 7C is a cross-sectional view taken along the line CC ′ in FIG.

FIG. 8 is a plan view of the liquid crystal display device according to the embodiment of the present invention.

FIG. 9 is a sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 10 is a plan view of a conventional liquid crystal display device.

11 is a diagram showing a driving waveform of a scanning voltage in FIG.

FIG. 12 is a plan view of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Array board | substrate 2 ... Counter substrate 3, 8, 61, 68 ... Glass substrate 4, 64 ... Scan line 5 ... Signal line 6 ... Thin film transistor 7, 67 ... Pixel electrode 9 ... Counter electrode 10, 70 ... Liquid crystal 41 ... Dummy wiring

Claims (6)

[Claims] A first substrate, a plurality of scanning lines formed in parallel on the first substrate, a switching element switched by a scanning voltage applied to the scanning line, and a switching element connected to the switching element. An array substrate having a pixel electrode, a second substrate, a counter electrode formed on the second substrate,
And a liquid crystal sandwiched between the array substrate and the counter substrate, wherein the scanning lines have m groups (m is a natural number of 2 or more) in equal numbers.
And the scanning directions in the k-th group (k = 1, 2,..., M−1) are different from the scanning directions in the k + 1-th group. A capacitance formed between a pixel electrode that is switched by a switching element connected to any one of the two scanning lines sandwiching any one of the scanning lines except for the scanning lines at both ends in each group; The liquid crystal display device is scanned from the larger scanning line to the smaller scanning line. 2. A first substrate, a plurality of scanning lines formed in parallel on the first substrate, a switching element switched by a scanning voltage applied to the scanning line, and a connection to the switching element. An array substrate having a pixel electrode, a second substrate, a counter electrode formed on the second substrate,
And a liquid crystal sandwiched between the array substrate and the counter substrate, wherein the scanning lines have m groups (m is a natural number of 2 or more) in equal numbers.
And the scanning directions in the k-th group (k = 1, 2,..., M−1) are different from the scanning directions in the k + 1-th group. Of the two scanning lines sandwiching an arbitrary scanning line except for the scanning lines at both ends in each group, the scanning having a shorter distance from a pixel electrode switched by a switching element connected to the arbitrary scanning line. A liquid crystal display device, which is scanned toward a scanning line far from the line. 3. The liquid crystal display according to claim 1, wherein the scanning line is divided into two groups, and the scanning direction of each group is repeatedly scanned from a side closer to the other group to a side farther from the other group. apparatus. 4. The liquid crystal display device according to claim 1, wherein a dummy wiring is formed at a boundary of each group in parallel with the scanning line. 5. The liquid crystal display device according to claim 1, wherein the switching element is a thin film transistor. 6. The liquid crystal display device according to claim 1, wherein the switching element is an MIM element in which a metal, an insulator, and a metal are stacked.