JPH10197899A - Active matrix type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the active matrix type liquid crystal display device which is improved in aperture rate. SOLUTION: The aperture rate of pixel opening parts 43R and 43G corresponding to colored layers 44R and 44G of red and green adjacent to a coupling part 59 is smaller than that of a pixel opening part 43B corresponding to a nonadjacent colored layer 44B of blue, so while a sufficient coupling area for a seal area is secure, the mean aperture rate is improved. The said pixel opening parts 43R and 43G are offset to the side of the said pixel opening part 43B and pitches by dots as minimum unit become equal intervals. The aperture rate of the said pixel opening part 43B is made large, so colors which are close to natural colors are obtained even when a three-wavelength type fluorescent lamp which has relatively low luminance of blue is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, a display device using liquid crystal has been put to practical use as a flat panel display replacing a cathode ray tube (CRT). Among them, an active matrix type liquid crystal display device provided with a thin film transistor as a switching device is excellent. In particular, attention has been paid to achieving high display quality, large area and high definition.

The active matrix type liquid crystal display device has a small size, light weight and low power consumption, and has been widely used in displays for notebook type personal computers. A response is urgently needed, and a large display screen area is indispensable for a response to multimedia.

[0004] However, in general, the active matrix type liquid crystal display device has an unavoidable increase in cost because the yield of non-defective products decreases with an increase in display area.

Therefore, Japanese Patent Application Laid-Open No. 7-5613 discloses an active matrix type liquid crystal display device which suppresses an increase in cost.
A configuration described in Japanese Patent Application Publication No. 6-206 is known. This Japanese Patent Laid-Open No. 7-
Japanese Patent No. 56136 describes an active matrix type liquid crystal display device in which the yield is improved even on a large screen by forming a display region by combining two or more liquid crystal displays and disposing them without gaps.

A configuration for forming a display area by combining the liquid crystal displays will be described with reference to FIGS.

As shown in FIGS. 11 to 13, a counter electrode substrate 2 is disposed so as to face an active matrix substrate 1, and a liquid crystal layer having been subjected to an alignment treatment is provided between the active matrix substrate 1 and the counter electrode substrate 2. Hold 3
The liquid crystal display panel 4 is configured. On the active matrix substrate 1, thin film transistors 5 as switching elements are arranged in a matrix, and pixel electrodes 6 such as ITO are arranged corresponding to the thin film transistors 5. Further, the counter electrode substrate 2 is provided with a counter electrode 7 facing the pixel electrode 6 and a black matrix 8. The black matrix 8 has pixel openings 9 corresponding to the pixel electrodes 6 in a matrix. These pixel openings 9 are provided with red, green or blue colored layers 11R, 11G and 11B. A seal region 12 for sealing the liquid crystal layer 3 is formed around the active matrix substrate 1 and the counter electrode substrate 2.

[0008] Then, the first liquid crystal display panel 4 ₁ on the left side has a connection terminal to an external driving circuit (not shown) on the left side, the second liquid crystal display panel positioned on the right side 4
_2, includes a connection terminal to an external driving circuit (not shown) on the right side, the free side between the connection terminals of the first liquid crystal display panel 4 ₁ of the right side and the second liquid crystal display panel 4 ₂ on the left side of the A large display area is formed by the combination.

[0009]

However, in the above-mentioned conventional example, since the sealing region 12 cannot be formed in the pixel opening 9, the aperture ratio of the pixel opening 9 adjacent to the coupling portion is lower than that of the other portions. Becomes As described above, when the aperture ratio of the pixel opening 9 is set to be low only in the vicinity of the joint 15,
It appears as if a line defect occurred on the display along. Therefore, as shown in FIG. 13, the width W1 of the coupling portion 15 is made equal to the width W2 of the other portion, and the aperture ratio is reduced in the portion including the coupling portion 15 and the peripheral portion, so that the aperture ratio decreases. However, there is a problem that it is difficult to increase the aperture ratio, and as the pixel pitch of the pixel openings 9 becomes smaller, the aperture ratio decreases significantly.

The present invention has been made in view of the above problems, and has as its object to provide an active matrix liquid crystal display device having an improved aperture ratio.

[0011]

According to the present invention, there are provided a plurality of scanning lines, a plurality of signal lines intersecting the scanning lines, switching elements connected to the scanning lines and the signal lines, and electrically connected to the switching elements. An active matrix substrate having a pixel electrode formed thereon, a counter substrate disposed to face the active matrix substrate, and having a counter electrode facing the pixel electrode, and at least one of the active matrix substrate and the counter substrate. An active matrix comprising: a black matrix provided with a pixel opening; a coloring layer provided in the pixel opening; and a liquid crystal layer that has been subjected to an alignment process and is sandwiched between the active matrix substrate and the counter substrate. An active matrix matrix liquid crystal display panel that is continuously joined at the joint to form a display area In Torikusu type liquid crystal display device, than the aperture ratio of the pixel opening portion adjacent to said coupling unit,
The display area has a larger average aperture ratio. Since the average aperture ratio of the display region is larger than the aperture ratio of the pixel opening adjacent to the coupling portion, the average aperture ratio of the display region is improved while the coupling region is sufficiently secured at the coupling portion.

Further, the pixel openings of the colored layers corresponding to the colors not adjacent to the joint are larger than the pixel openings corresponding to the colored layers of the color adjacent to the joint. Then, the opening ratio of the pixel opening of the coloring layer of the color adjacent to the coupling portion is
Since the pixel opening of the colored layer corresponding to the color that is not adjacent to the joint is large, the average aperture ratio of the display area is improved while the joint is sufficiently secured at the joint.

Further, the coloring layer has red, green and blue, and the coloring layer corresponding to the large pixel opening is blue. Then, by increasing the size of the pixel opening corresponding to the blue colored layer for which it is difficult to obtain relatively large luminance,
Balancing the red, green and blue intensities to approximate the desired color.

Still further, the pixel opening is minimum at a portion adjacent to the joint, and continuously increases as the distance from the joint increases. The average aperture ratio of the display area is improved while the coupling area is sufficiently secured by continuously increasing the pixel aperture as the distance from the coupling section increases.

Further, a backlight is provided on the back surface of the active matrix type liquid crystal display panel, and the light distribution characteristics of the backlight are changed according to the change of the pixel aperture ratio. By making the light distribution characteristics of the backlight correspond to changes in the pixel aperture ratio, power consumption can be suppressed and brightness can be balanced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the active matrix type liquid crystal display device of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 to 3, for example, a tantalum gate electrode 22, a storage capacitor electrode line and a gate electrode (not shown) are formed on a glass substrate 21 which is a light-transmitting insulating substrate.
A scanning line 23 connected to the gate electrode 22 is formed.
The glass substrate 21 including the scan lines 23 and the gate lines 22 is covered with a gate insulating film 24 of silicon oxide (SiO _x ).

The gate electrode 22 of the gate insulating film 24
Above the channel layer 25, an amorphous silicon (a-Si) channel layer 25 is formed. Above the channel layer 25, an etching protection film 26 of silicon nitride (SiN _x ) is formed. On the side, a drain region 27 of n ⁺ type amorphous silicon (n ⁺ type a-Si) is formed, and on the other end side, a source region 28 is formed.
On the other hand, on the gate insulating film 24, ITO (Indium Tin Oxi
The de) pixel electrodes 31 are arranged in a matrix. On the drain region 27, for example, an aluminum drain electrode 32 and a signal line 33 connected to the drain electrode 32 are formed, and between the source region 28 and the pixel electrode 31, an aluminum source electrode 34 is formed. Inverted staggered thin film transistor (Thin F)
ilm Transistor) 35 is formed. Further, a protective insulating film 36 of silicon nitride (SiN _x ) is formed so as to cover these thin film transistors 35, and an active matrix substrate 37 is formed.

On the other hand, a glass substrate 41 which is a light-transmitting insulating substrate
A black matrix 42 of chromium (Cr) is formed on the top, and pixel openings 43R, 43B, 43G in a matrix are formed in the black matrix 42. Red (R), blue (B), and green (G) coloring layers 44R, 44B, and 44G are formed in the pixel openings 43R, 43B, and 43G, respectively, and are formed on these coloring layers 44R, 44B, and 44G. In
A counter electrode 45 of ITO is formed, and a counter substrate 46 is formed.

Further, low-temperature cure type polyimide alignment films 51 and 52 are provided on opposite surfaces of the active matrix substrate 37 and the counter substrate 46 at different light distribution axes at an angle of about 90 °.

Then, the active matrix substrate 37 and the opposing substrate 46 are opposed to each other, the liquid crystal layer 53 is sandwiched, and a sealing region 54 is formed around the liquid crystal layer 53 and sealed.

Further, polarizers 56 and 57 are respectively provided on the surfaces of the active matrix substrate 37 and the counter substrate 46 which are not opposed to each other.
Are formed, and the liquid crystal display panel 58 is formed.

At one end of each of the liquid crystal display panels 58, connection terminals for an external drive circuit (not shown) are provided. As shown in FIG. 4, a plurality of, for example, two first liquid crystal display panels 58 _{1 are provided.} and a second liquid crystal panel 58 ₂ are connected at the junction 59 such as an adhesive, it is disposed a backlight large screen active matrix type liquid crystal display of having such back (not shown) on the side of for example 3-wavelength type fluorescent lamps Device 60
Is completed.

The two liquid crystal display panels 58 ₁ , 58 ₁ ,
58 ₂ of the pixel opening portion 43R, 43B, the 43G, as shown in FIGS. 1, 2 and 5, although any length in the length direction are equal, the colored layer 44R red adjacent to the coupling portion 59 and the The pixel openings 43R and 43G corresponding to the green coloring layer 44G are formed to be narrower than the pixel openings 43B corresponding to the blue coloring layer 44B not adjacent to the joint 59, and the red color adjacent to the joint 59 is formed. The aperture ratio of the pixel openings 43R and 43G corresponding to the layer 44R and the green coloring layer 44G is smaller than the average aperture ratio including the pixel opening 43B corresponding to the blue coloring layer 44B not adjacent to the coupling portion 59. Further, the aperture ratio of the pixel opening 43B corresponding to the blue coloring layer 44B is formed larger than the aperture ratio of the pixel openings 43R and 43G corresponding to the red coloring layer 44R and the green coloring layer 44G. Further, pixel openings 43R and 43G corresponding to the red coloring layer 44R and the green coloring layer 44G, respectively.
Are offset by the pixel openings 43B corresponding to the blue colored layers 44B.

Next, the manufacturing process of the above embodiment will be described.

First, a 300 nm tantalum film is formed on one main surface of a glass substrate 21 by sputtering, and this tantalum film is photo-etched into a predetermined shape to form a gate electrode 22, a scanning line 23, and an auxiliary capacitance electrode (not shown). Form a line.

Next, a silicon oxide film is formed to a thickness of 350 nm.
An amorphous silicon film having a thickness of 50 nm and a silicon nitride film having a thickness of 150 nm are each formed by a plasma CVD method. After that, first, the silicon nitride film is etched into a predetermined shape to process the etching protection film 26 into a predetermined shape, and the n ⁺ -type amorphous silicon film is
Then, the n ⁺ -type amorphous silicon film and the amorphous silicon film are processed into a predetermined shape to form a channel layer 25, a drain region 27, and a source region 28.
To form

Then, the ITO film is coated with a thickness of 100 nm by the Spack method, and processed into a predetermined shape by the photo etching method to form the pixel electrode 31.

Further, an aluminum film is coated with a thickness of 500 nm by a sputtering method, and the drain electrode 32, the signal line 33 and the source electrode 34 are processed into a predetermined shape by a photo etching method. At this time, one ends of the drain electrode 32 and the source electrode 34 are brought into contact with the drain region 27 and the source region 28, and a thin film transistor 35 is formed.

Further, a silicon nitride film having a thickness of, for example, 200 nm is formed on the thin film transistor 35 by plasma CVD.
An active matrix substrate 37 is completed by forming a protective insulating film 36 over the entire surface by a method.

On the other hand, on one main surface of the glass substrate 41, a chromium film is formed and pixel openings 43R, 43B, 43G are formed to form a black matrix 42. In addition, coloring layers 44R, 44B, 44G are formed corresponding to the pixel openings 43R, 43B, 43G of the black matrix 42, and further, a counter electrode is formed.
The counter substrate 46 is completed by forming 45.

On one main surface of each of the active matrix substrate 37 and the counter substrate 46, an alignment film is formed on the entire surface.
An alignment process is performed by forming 51 and 52 and rubbing the surfaces of the alignment films 51 and 52 in a predetermined direction with a cloth or the like.

Furthermore, one main surface of each of the active matrix substrate 37 and the counter substrate 46 faces each other, and
Combination such that the orientation axes of 51 and 52 are almost 90 °,
A liquid crystal layer 53 is formed by forming a seal region 54 around the periphery and sealing and sandwiching liquid crystal in a gap between the active matrix substrate 37 and the counter substrate 46, thereby completing a liquid crystal display panel 58.

When a large-screen active matrix type liquid crystal display device 60 is formed by joining a plurality of, for example, two, liquid crystal display panels 58, as shown in FIG. First connection terminal provided with a connection terminal
The liquid crystal display panel 58 _1, and a liquid crystal display panel 58 ₂ second in which a connection terminal with an external drive circuit to the right side of the display area, without the side of the display area end of the connection terminal to an external driving circuit, respectively Facing each other, a bonding portion 59 is formed with an adhesive and bonded.

[0035] In addition, the first liquid crystal display panel 58 ₁ and the second
After combining the liquid crystal display panel 58 _{and second,} in the other main surface of the active matrix substrate 37 and the counter substrate 46, respectively attached polarizing plates 56 and 57, an active matrix type liquid crystal display device 60 is completed with a large screen .

Next, the operation of the above embodiment will be described.

As described above, the aperture ratios of the pixel openings 43R and 43G corresponding to the red coloring layer 44R and the green coloring layer 44G adjacent to the joint 59 are different from those of the blue coloring layer 44B not adjacent to the joint 59. Since the aperture ratio of the pixel aperture 43B corresponding to the pixel aperture 43B is smaller than that of the related art, the average aperture ratio of the entire pixel apertures 43R, 43B, and 43G is improved while securing a sufficient coupling area of the seal area 54. I have.

The red colored layer 44 adjacent to the joint 59
R and the pixel openings 43R corresponding to the green colored layer 44G,
43G is offset toward the pixel opening 43B corresponding to the blue coloring layer 44B, so that the pixel openings 43R, 44R, 44G, 44G corresponding to the red, blue, and green coloring layers 44R, 44G, 44B.
The pitch of each dot having the combination of 43B and 43G as the minimum unit is equal.

Further, the aperture ratio of the pixel opening 43B corresponding to the blue coloring layer 44B is formed larger than the aperture ratio of the pixel opening 43R, 43G corresponding to the red coloring layer 44R and the green coloring layer 44G. This makes it possible to easily obtain a color close to nature even if a three-wavelength fluorescent lamp having a relatively low blue luminance is used.

A three-wavelength fluorescent lamp used for a backlight is a blue colored layer whose luminance is difficult to increase.
Although the aperture ratio of the pixel opening 43B corresponding to 44B is selectively improved, the aperture ratio may be improved by selecting another color according to the luminance of each color of the light source to be used.

Next, another embodiment will be described with reference to FIGS.

The embodiment shown in FIGS. 6 to 8
In the embodiment shown in FIGS. 1 to 5, the opening ratio of the opening pattern of the black matrix 42 is minimized in the portion adjacent to the connecting portion 59, and the opening ratio continuously increases as the distance from the connecting portion 59 increases. At the maximum aperture ratio. That is, the first liquid crystal display panel 58 _first, the blue from the coupling portion 59 side, green and red colored layers 44B, 44G, the pixel opening 43B corresponding to 44R on the left side
, 43G, the aperture ratio increases in the order of 43R, the second liquid crystal panel 58 _2, red from the coupling portion 59 side located on the right side,
The aperture ratios increase in the order of the pixel openings 43R, 43G, 43B corresponding to the green and blue coloring layers 44R, 44G, 44B.
Therefore, it is possible to improve the average aperture ratio of the pixel openings 43R, 43B, and 43G while securing a sufficient coupling region.

The aperture ratio distribution in this case is lower at the center of the coupling portion 59 as shown by the broken line A in FIG. Since the aperture ratio is high, the overall aperture ratio can be reduced by combining the backlight with the light distribution characteristic having the highest luminance at the center indicated by the broken line A in FIG. Power consumption can be reduced as compared with the case where the power consumption is suppressed low.

In the above-described embodiment, the two liquid crystal display panels 58 ₁ and 58 ₂ are combined to increase the size. However, the same effect can be obtained by combining four or a plurality of other liquid crystal display panels. be able to.

The red, blue and green colored layers 44R
, 44G, 44B and the black matrix 42 to the opposite substrate 4
Although the case where it is provided on the sixth side has been described, the same effect can be obtained by providing it on the active matrix substrate 37 side.

Further, the matrix array substrate 37 having the inverted staggered type thin film transistor 35 using amorphous silicon as the semiconductor has been described. However, even when the polycrystalline silicon is used as the semiconductor or the forward staggered type thin film transistor is used. The same effect can be obtained.

[0047]

According to the present invention, since the average aperture ratio of the display area is larger than the aperture ratio of the pixel opening adjacent to the joint, the average of the display area can be sufficiently secured at the joint. The aperture ratio can be improved, and a large screen active matrix type liquid crystal display device in which a plurality of liquid crystal display panels are combined can increase display luminance and reduce power consumption with a good yield.

Further, since the pixel opening of the color layer corresponding to the color not adjacent to the coupling portion is larger than the aperture ratio of the pixel opening of the coloring layer of the color adjacent to the coupling portion, the coupling portion can sufficiently cover the coupling region. While improving the average aperture ratio of the display area.

Further, by increasing the size of the pixel opening corresponding to the blue colored layer for which it is difficult to obtain a relatively large luminance, it is possible to balance the luminances of red, green, and blue and to approach a desired color.

Furthermore, the average aperture ratio of the display area can be improved while securing a sufficient coupling region at the coupling portion by continuously increasing the pixel aperture as the distance from the coupling portion increases.

Further, by making the light distribution characteristics of the backlight correspond to changes in the pixel aperture ratio, it is possible to suppress power consumption and balance brightness.

[Brief description of the drawings]

FIG. 1 is a partially cutaway plan view of an embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG. 1;

FIG. 4 is an explanatory view showing coupling of two liquid crystal display panels according to the first embodiment.

FIG. 5 is a schematic diagram showing a state of the liquid crystal display device.

FIG. 6 is a plan view of the liquid crystal display device according to another embodiment of the present invention, with a portion cut away.

FIG. 7 is a sectional view taken along the line VII-VII of FIG. 6;

FIG. 8 is a schematic diagram showing a state of the liquid crystal display device.

FIG. 9 is a graph showing an aperture ratio distribution of the liquid crystal display device.

FIG. 10 is a light distribution characteristic diagram showing a luminance distribution of the backlight.

FIG. 11 is a plan view of a conventional liquid crystal display device with a part cut away.

FIG. 12 is a sectional view taken along the line XII-XII of FIG. 11;

FIG. 13 is a schematic diagram showing a state of the liquid crystal display device.

[Explanation of symbols]

 23 Scanning line 31 Pixel electrode 33 Signal line 35 Thin film transistor as switching element 37 Active matrix substrate 42 Black matrix 43R, 43G, 43B Pixel opening 44R, 44G, 44B Color layer 45 Counter electrode 46 Counter substrate 53 Liquid crystal layer 59 Coupling part

Claims (5)

[Claims] An active matrix having a plurality of scanning lines, a plurality of signal lines intersecting the scanning lines, switching elements connected to the scanning lines and the signal lines, and pixel electrodes electrically connected to the switching elements. A substrate, a counter substrate disposed to face the active matrix substrate and having a counter electrode facing the pixel electrode, and a black having a pixel opening provided in at least one of the active matrix substrate and the counter substrate. An active matrix type liquid crystal display panel comprising a matrix, a coloring layer provided in the pixel opening, and a liquid crystal layer which has been subjected to an alignment process and is sandwiched between the active matrix substrate and the counter substrate is combined. Active matrix type liquid crystal display device with a display area formed by combining The active matrix type liquid crystal display device, wherein an average aperture ratio of the display area is larger than an aperture ratio of a pixel aperture adjacent to the coupling portion. 2. The pixel opening of a colored layer corresponding to a color that is not adjacent to a coupling portion is larger than a pixel opening corresponding to a coloring layer of a color adjacent to the coupling portion. Active matrix type liquid crystal display device. 3. The active matrix type liquid crystal display device according to claim 1, wherein the colored layer has red, green and blue, and the colored layer corresponding to the large pixel opening is blue. . 4. The active matrix type liquid crystal according to claim 1, wherein the pixel opening is minimum at a portion adjacent to the coupling portion and continuously increases as the distance from the coupling portion increases. Display device. 5. The backlight according to claim 1, wherein a backlight is provided on a back surface of the active matrix type liquid crystal display panel, and a light distribution characteristic of the backlight is changed according to a change in a pixel aperture ratio. The active matrix liquid crystal display device according to any one of the above.