JP3397810B2 - Liquid crystal display - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to a liquid crystal display device having a non-linear element.

[0002]

2. Description of the Related Art Active matrix type liquid crystal display devices, which are influential flat displays, have begun to be mass-produced. The flat display occupies a small space,
Due to its light weight, it is used for display devices of portable computers and display parts of industrial machines. In the future, the screens will become larger and the definition will become higher, and it is expected that home-use televisions will be applied. In a liquid crystal display device using a thin film transistor as a drive element, there is a method of forming a drive circuit on the same substrate as a pixel as a powerful means for achieving high definition. FIG. 5 is a perspective view showing a part of the structure of a conventional liquid crystal display device with a built-in drive circuit in an easily understandable manner. FIG. 5 is an imitation view of a liquid crystal display device as if the counter substrate was partially cut away. An X-side drive circuit 502 including a thin film transistor and a Y-side drive circuit 503 are formed outside the sealing portion 504 on a glass substrate 501. From the X-side drive circuit 502, a data line 505 and a Y-side drive circuit are driven. A gate line 506 extends from the circuit 503 to the display region through the sealing portion 504, and a thin film transistor for supplying a signal to the pixel 507 is formed at the intersection of the data line 505 and the gate line 506. There is. The source region of the thin film transistor and the data line 505 are electrically connected to each other through the through hole 508, and the drain region and the pixel electrode 507 are electrically connected to each other through the through hole 509. The signal on the data line 505 is transmitted to the pixel electrode 507 by the potential of the gate electrode 510.

External terminals 511 and 512 are connected to the X-side drive circuit and the Y-side drive circuit. A video signal necessary for image display, a clock signal for driving a driving circuit, and a driving potential signal are transmitted to the external terminal.

Substrate 50 on which picture element electrodes 507 are formed
A liquid crystal is sealed between 1 and the counter substrate 513 on which the common electrode is formed to form an active matrix liquid crystal display device.

FIG. 6 is a plan view of a substrate on which the pixel electrodes of the liquid crystal display device of FIG. 5 are formed. X side drive circuit 60
2 and the data line 605 extending from 2 and the Y side drive circuit 60
The gate lines 606 extending from 3 reach the display area through the liquid crystal sealing unit 604, and the data lines 60
A thin film transistor is formed at the intersection of 5 and the gate line 606.

FIG. 7 is a schematic plan view of an active matrix substrate. Data line 705 and gate line 70
A thin film transistor 714 that switches a pixel is formed at the intersection of 6 and 6. The number of pixels required to sufficiently express a moving image is about 400 columns on the X side and about 300 rows on the Y side. Then, in the case of a liquid crystal display device having a built-in drive circuit as in the conventional art, 400 or more data lines and 300
A structure in which more than one gate line passes through the liquid crystal sealing portion 704 has been adopted.

Further, FIG. 8 shows a schematic view of a cross section taken along the line AA ′ in FIG. 6 in the vicinity of the liquid crystal sealing portion of the conventional liquid crystal display device.

A thin film transistor is formed on a glass substrate 801, and a pixel electrode 8 is formed in its drain region 816.
07 is connected. The pixel electrode 807 is deposited on the interlayer insulating film 817 made of a silicon oxide film. A liquid crystal 820 is sealed between the counter substrate 813 on which the common electrode 819 is formed and the glass substrate 801. Further, the drive circuit is formed outside the liquid crystal sealing unit 804.

[0009]

However, in the structure of the above-mentioned conventional liquid crystal display device, there are several hundreds of wirings passing through the liquid crystal sealing portion, including the data line and the gate line.
Therefore, in a high-temperature and high-humidity environment, components such as water, carbon dioxide, and nitric oxide enter from the interface between the data line or gate line and the liquid crystal encapsulation, which causes the liquid crystal to deteriorate and display characteristics to significantly deteriorate. There is a problem that the liquid crystal display device cannot be used for a long period of time.

[0010]

According to the present invention, a liquid crystal is sandwiched inside a sealing portion between a pair of substrates, and a transistor is provided inside the sealing portion of one of the pair of substrates. And an interlayer insulating film on the transistor and the interlayer insulating film
A pixel electrode arranged via the upper organic film and a drive circuit for driving the transistor are provided, and the interlayer insulating film is arranged on a region of the one substrate facing the sealing portion.
And the organic film is formed on the interlayer insulating film as the sealing portion.
The organic film is disposed in close contact with the drive circuit.
A counter electrode is disposed in a region corresponding to the pixel electrode on the other substrate of the pair of substrates, and the counter electrode is not disposed in a region facing the drive circuit. It is characterized by According to the present invention, a liquid crystal is sandwiched inside a sealing portion between a pair of substrates, a transistor is provided inside the sealing portion of one of the pair of substrates, and an interlayer insulating film is provided on the transistor. And the layer
A pixel electrode arranged via a flat film on an insulating film and a drive circuit for driving the transistor are provided, and the interlayer insulation is provided on a region of the one substrate facing the sealing portion.
An edge film is arranged, and the flat film is formed on the interlayer insulating film.
It is arranged in close contact with the sealing portion, and the
A flat film is arranged , a counter electrode is arranged in a region corresponding to the pixel electrode on the other substrate of the pair of substrates, and the counter electrode is arranged in a region facing the drive circuit. It is characterized by not being placed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic perspective view in which the internal structure of the liquid crystal display device is easy to understand and a part of the counter substrate is removed.

An X-side drive circuit 102 and a Y-side drive circuit 10 in which a thin film transistor circuit is assembled on a glass substrate 101.
3 are configured. These drive circuits are the liquid crystal sealing unit 1.
It is located inside 04. The data line 105 is from the X side drive circuit, and the gate line 1 is from the Y side drive circuit.
06 extends to the display area. The data line 105 is electrically connected to the source region of the thin film transistor for switching the pixel 107 in the display area through the through hole 108, and the drain region of the thin film transistor is electrically connected to the pixel 107 through the through hole 109. . The gate line 106 also serves as the gate electrode 110 of each thin film transistor so as to switch the display area. Liquid crystal is sandwiched between a glass substrate 101 on which a thin film transistor is formed and a counter substrate 113 on which a common electrode is formed, and the liquid crystal is sealed by a liquid crystal sealing portion 104. Further, the X side drive circuit 102 has a clock signal,
A wiring for a video signal or the like is connected, passes through the liquid crystal sealing portion 104, and is connected to the external terminal 111. Similarly, in the Y-side drive circuit as well, wirings for clock signals and the like are connected to the external terminals 112. Further, a conductive film 114 made of the same material as the pixel electrode is formed above the X-side drive circuit and the Y-side drive circuit with the organic thin film interposed therebetween.

FIG. 2 shows an enlarged plan view of a part of the active matrix substrate in which the thin film transistor of the liquid crystal display device of the invention is formed. The driving circuit is formed inside the liquid crystal sealing portion, and a thin film transistor is formed at the intersection of the data line 205 extending from the X side driving circuit 202 to the display region and the Y side driving circuit 203 and the gate line 206. Further, wirings 211 and 212 necessary for driving the drive circuit pass through the liquid crystal sealing portion 204 and extend from the drive circuit to the outside. Also, in order to increase the aperture ratio of the pixel electrode, overlap the gate line and part of the pixel electrode,
Furthermore, the source line and a part of the pixel electrode are overlapped. That is, the gate line and the data line are light-shielding films that block the light incident from the back surface of the active matrix in regions other than the pixel portion of the display region. At this time, since the organic thin film having a thickness of 1 μm or more is formed between the gate line or the source line and the pixel electrode, the distortion of the signal applied to the pixel electrode hardly occurs.

FIG. 3 is a schematic plan view of an active matrix substrate in which the pixel electrodes of the liquid crystal display device of FIG. 1 are formed.

From the X-side drive circuit 302 to the data line 30
5, a gate line 306 extends from the Y-side drive circuit 303 to the display area, and a thin film transistor and a pixel electrode 307 are formed at the intersection of the data line and the gate line.

Since the drive circuit is formed on the display area side of the liquid crystal sealing portion 304, hundreds of data lines 305 extending from the X side drive circuit 302 and the Y side drive circuit 303 are formed.
Hundreds of gate lines 306 extending from each do not pass through the liquid crystal sealing portion 304. Instead, the wirings 311 and 312 passing through the liquid crystal sealing portion are dozens of wirings necessary for driving the driving circuit from the outside. As described above, the number of wirings passing through the liquid crystal sealing portion is remarkably reduced, so that water and gas which cause deterioration of the liquid crystal entering the display area are extremely reduced. Therefore, it has become possible to use a stable and high-quality liquid crystal display device for a long period of 10 times or more than before.

Next, FIG. 4 shows a sectional view of the active matrix substrate taken along the line AA 'in FIG. In this figure, an interlayer insulating film which cannot be represented in FIG. 1 is shown. A drive circuit 402 formed of a thin film transistor is formed on a glass substrate 401 inside a liquid crystal sealing portion. A pixel to which a signal is applied by the thin film transistor in the display area is an interlayer insulating film 417 made of a silicon oxide film and an organic thin film 418.
Formed on.

By forming the organic thin film, the surface of the display region becomes flat, and the pixel electrodes are formed on this flat plane. Therefore, the interval between the common electrode and the pixel electrode of the counter substrate becomes uniform at any part. Therefore, the liquid crystal has the same degree of rotation, which enables uniform high-quality display.

[0020]

As shown in FIG. 8 of the conventional example, when the pixel electrode 807 is formed directly on the interlayer insulating film 817, the pixel electrode is stepped depending on the vertical shape of the interlayer insulating film 817. As a result, the common electrode 819 and the pixel electrode have a non-uniform spacing, resulting in uneven display characteristics. However, as in the present invention, the organic thin film 418 on the interlayer insulating film 415 has a flat surface regardless of the cross-sectional shape of the interlayer insulating film 417. Therefore, the pixel electrode 407 formed on the organic thin film 418 having a flat surface has a flat cross-sectional shape, and the distance between the pixel electrode 407 and the common electrode 419 is uniform over the entire display area. A high-contrast display can be obtained.

Further, the organic thin film 418 is used for the liquid crystal sealing portion 4.
Also formed under 04. Then, the surface of the organic thin film 418 becomes flat regardless of the cross-sectional shape of the wiring that passes through the liquid crystal sealing unit 404, so that the adhesiveness between the liquid crystal sealing unit 404 and the organic thin film 418 formed when the liquid crystal is sealed. Since it becomes extremely high, moisture and gas do not penetrate into the liquid crystal in the display area from the external environment, so that high-quality display characteristics can be maintained for a long time.

Further, a conductive film made of the material of the pixel electrode is formed simultaneously with the pixel electrode on each of the X-side and Y-side drive circuits with the organic thin film 418 interposed therebetween. This makes the top of the drive circuit of the active matrix substrate the same as the top of the display area, so when applying the liquid crystal aligning agent to the substrate and rubbing with a roll, the edge of the display area The rubbing unevenness was eliminated, and a screen with high quality display characteristics could be realized over the entire display area.

Further, in the case of the liquid crystal display device in which the conventional drive circuit is formed on the same substrate, since the drive circuit is formed outside the liquid crystal sealing portion, the number of data lines and gate lines is almost the same. Since the wiring passed through the liquid crystal encapsulation part, gas or water that deteriorates the liquid crystal enters the display area from the interface between the step part of the data line or gate line and the liquid crystal encapsulation part, and deteriorates the liquid crystal characteristics. However, there is a problem that display characteristics are deteriorated.

However, in the structure of the present invention, the number of wirings passing through the liquid crystal sealing portion is 20 at most, which is 1/40 or less of that in the conventional case, so that gas and moisture penetrating into the display area are significantly reduced. For this reason, it has become possible to manufacture a high-quality liquid crystal display device that can be used for a significantly longer period of time than ever before.

[Brief description of drawings]

FIG. 1 is a perspective structural view of a liquid crystal display device of the present invention.

FIG. 2 is a plan view of an active matrix substrate of a liquid crystal display device of the present invention.

FIG. 3 is a schematic plan view of an active matrix substrate of a liquid crystal display device of the present invention.

FIG. 4 is a cross-sectional view of a liquid crystal display device of the present invention.

FIG. 5 is a perspective structural view of a conventional liquid crystal display device.

FIG. 6 is a plan view of an active matrix substrate of a conventional liquid crystal display device.

FIG. 7 is a schematic plan view of an active matrix substrate of a conventional liquid crystal display device.

FIG. 8 is a sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

101, 201, 301, 401, 501, 601, 701, 801 ... Glass substrate 102, 202, 302, 402, 502, 602, 702, 802 ... X side drive circuit 103, 203, 303, 503, 603, 703 ... Y-side drive circuit 104, 204, 304, 404, 504, 604, 704, 804 ... Liquid crystal sealing unit 105, 205, 305, 505, 605, 705 ... Data line 106, 206, 306, 406, 506, 606, 706, 806 ... Gate lines 107, 207, 407, 507, 607, 807 ... Picture element electrodes 108, 208, 508, 608 ... Through holes 109, 209, 409, 509, 609, 809 in data lines and source regions ... Picture Through holes 110, 210, 510, 610 for element electrodes and gate lines ... Gate electrodes 111, 211, 311, 511, 611, 711 ... External wiring 112, 212, 312, 512, 612, 712 ... External wirings 113, 413, 513, 813 of the side driving circuit ... Opposing substrates 114, 414 ... Conductive thin films 315, 715 ... Thin film transistors 416, 816 ... Drain regions 417, 817 ... Interlayer insulating film 418 ... Organic Thin film 419, 819… Common power Poles 420, 820 ... Liquid crystal

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyofumi Kitawada               Seiko, 3-3-5 Yamato, Suwa City, Nagano Prefecture               -In Epson Corporation (72) Inventor Yoshiyuki Kitazawa               Seiko, 3-3-5 Yamato, Suwa City, Nagano Prefecture               -In Epson Corporation (72) Inventor Junri Shimone               Seiko, 3-3-5 Yamato, Suwa City, Nagano Prefecture               -In Epson Corporation (72) Inventor Hideyuki Akanuma               Seiko, 3-3-5 Yamato, Suwa City, Nagano Prefecture               -In Epson Corporation (72) Inventor Takashi Nakazawa               Seiko, 3-3-5 Yamato, Suwa City, Nagano Prefecture               -In Epson Corporation (72) Inventor Satoshi Inoue               Seiko, 3-3-5 Yamato, Suwa City, Nagano Prefecture               -In Epson Corporation                (56) References JP-A-58-85478 (JP, A)                 JP-A-2-42420 (JP, A)                 JP-A-4-68318 (JP, A)                 JP-A-6-118432 (JP, A)                 JP 62-251723 (JP, A)                 JP-A-2-157827 (JP, A)                 Japanese Patent Laid-Open No. 4-100022 (JP, A)                 Actual Kaihei 3-110486 (JP, U)                 Actual Kaihei 4-6030 (JP, U)

Claims (2)

(57) [Claims] 1. A liquid crystal is sandwiched inside a sealing portion between a pair of substrates, a transistor is provided inside the sealing portion of one substrate of the pair of substrates, and interlayer insulation is provided on the transistor. and the pixel electrode disposed over the film and the organic film on the interlayer insulating film, comprising a driving circuit for driving the transistor, said the opposing region on the sealing portion of the one substrate an interlayer insulating film is disposed on the interlayer insulating film <br/> disposed the organic film is adhered to the sealing portion, wherein
The organic film is disposed on a drive circuit, and a counter electrode is disposed on the other substrate of the pair of substrates in a region corresponding to the pixel electrode, and in a region facing the drive circuit. Is a liquid crystal display device in which the counter electrode is not arranged. 2. A liquid crystal is sandwiched inside a sealing portion between a pair of substrates, a transistor is provided inside the sealing portion of one substrate of the pair of substrates, and interlayer insulation is provided on the transistor. and the pixel electrode disposed over the membrane and a flat membrane on the interlayer insulating film, comprising a driving circuit for driving the transistor, on a region facing the sealing portion of the one of the substrates The interlayer insulating film is disposed, and the interlayer insulating film
The flat film is disposed on the sealing portion so as to be in close contact therewith ,
The flat film is disposed on the drive circuit, and a counter electrode is disposed on the other substrate of the pair of substrates in a region corresponding to the pixel electrode and faces the drive circuit. A liquid crystal display device, wherein the counter electrode is not arranged in a region.