JP2003005190A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the dislocation between substrates and the variation of a cell gap caused by the variation of the position of a columnar spacer due to the application of external force. SOLUTION: The top part of the columnar spacer SOC fixedly formed on the inner surface of one substrate of a pair of substrates SUB1 and SUB2 is positioned in a recessed part LYB of a multi-layered structure film LY that the other substrate has.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and in particular, a columnar spacer fixedly formed on one of a pair of substrates regulates a gap in which liquid crystal is sealed so that fluctuation of the gap due to application of an external force. The present invention relates to a suppressed liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device widely used as a thin, lightweight, and low power consumption display device has a liquid crystal sealed in a bonding gap between a pair of substrates having various wirings and electrodes for forming pixels formed on the inner surface thereof. Configured. Various types of liquid crystal display devices of this type are known depending on the pixel selection method. One of them is a simple matrix type in which a large number of parallel electrodes are laid on the inner surfaces of a pair of substrates and the electrodes of both substrates are laminated so as to intersect with each other. The other is an active matrix type in which a switching element represented by a thin film transistor (TFT) is formed on the inner surface of at least one of the pair of substrates.

The active matrix type includes, for example, a TDT type using a thin film diode or a MIM type in addition to a thin film transistor as its switching element.
Various other formats are known. In addition, for example, in the thin film transistor type, a so-called TN type in which electrodes and wirings for pixel formation are provided on both inner surfaces of a pair of substrates, and an electrode and wiring for pixel formation are formed only on one inner surface of the pair of substrates. The so-called IPS type is known.

FIG. 5 is a sectional view for explaining an example of the main structure of a TN type liquid crystal display device using a thin film transistor as a switching element. In the figure, SUB1 is a lower substrate,
The SUB 2 is an upper substrate, and has a multilayer structure film including wiring for forming pixels, an electrode, an insulating layer, and other functional films on the inner surface of each substrate. A thin film transistor TFT is provided on the inner surface of the lower substrate SUB1, and the upper substrate SUB
A common electrode COM and three color filter layers FIL (FIL (R), FIL (G), FIL (B),
.. FIL (B) is not shown).

The thin film transistor TFT has a scan electrode (gate electrode) GT connected to a scan wiring (not shown), a semiconductor layer AS, a source electrode SD1 and a drain electrode SD2, and a pixel electrode ITO1 is formed in connection with the source electrode SD1. ing. Besides, it has a gate insulating layer GI, a passivation layer PSV1, etc., and is a thin film transistor TFT.
An alignment film ORI1 is applied to the entire surface including the above to form a multilayer structure film. In the figure, reference numerals d0, d1, d2, d
Reference numeral 3 is a metal film forming each layer.

Further, on the inner surface of the upper substrate SUB2, color filter layers FIL (FIL (R), FIL (G), FIL (R), FIL (G), which are divided by a black matrix BM as a light shielding layer, are formed.
FIL (B)), passivation layer PSV2, ITO
A common electrode (COM) shown by 2 and a multi-layer structure film including the alignment film ORI2 are formed. As shown in the figure, unevenness is formed on the surface of the multi-layered structure film on the lower substrate SUB1 and the upper substrate SUB2. The liquid crystal LC is sealed between the pair of substrates to form a liquid crystal display device.

Then, the pixel electrode ITO1 and the common electrode IT
By applying an electric field between O2, the liquid crystal LC in between
Of the polarizing plate PO attached to the outer surface of the upper substrate SUB2 by modulating the polarization axis of light incident through the polarizing plate POL1 attached to the outer surface of the lower substrate SUB1.
An image is displayed by the light emitted from L2. At this time, if the cell gap, which is the layer thickness of the liquid crystal layer LC, changes, a predetermined display characteristic cannot be obtained. Therefore, a gap regulating member called a spacer is inserted in the bonding gap (so-called cell gap) between the pair of substrates. ing.

Glass or plastic beads (spacer beads) have been widely used as the spacers. The spacer beads are sprayed on the inner surfaces of the substrates by a spray method or the like before the pair of substrates are bonded together. Therefore, the spacer beads are also present in the area including the pixel area, which is one of the causes of deterioration of display quality such as light leakage. Instead of such spacer beads, there has been developed one in which a gap regulating member is fixedly formed on the inner surface of one of a pair of substrates and in a portion avoiding the pixel region. This gap regulating member is called a columnar spacer, and is formed by a photolithography technique so as to have a top on one inner surface of a pair of substrates that abuts on the other inner surface.

When the columnar spacer is in the pixel region, a part of the light that is incident from the lower substrate SUB1 and passes through the liquid crystal is transmitted through the columnar spacer, so-called light leakage occurs, and the display quality such as contrast is deteriorated. Cause of. Therefore, the installation position of the columnar spacer is a portion avoiding the pixel region.

FIG. 6 is a plan view of an essential part for explaining an example of the installation position of the columnar spacer in the conventional liquid crystal display device.
FIG. 6 shows a state in which the lower substrate is viewed from the upper substrate, and the multilayer structure film of the upper substrate shows the opening of the black matrix BM as an outline. In the figure, SUB1 is a lower substrate, and scanning lines GL, signal lines DL, thin film transistors TFT, and pixel electrodes ITO1 are formed on the inner surface thereof. The columnar spacer SOC is the scanning line GL which is a portion avoiding the pixel region.
Alternatively, it is fixedly formed on the inner surface of the upper substrate so as to be located above the signal line DL.

[0011]

The scanning wiring GL and the signal wiring DL on which the columnar spacer SOC is formed are formed on the lower substrate SB.
In this arrangement of columnar spacers, a pair of substrates are bonded together, and then the wiping operation for cleaning the substrate surface is performed as follows. The phenomenon is likely to occur.

FIG. 7 is a cross-sectional view of an essential part for schematically explaining a substrate displacement phenomenon caused by a conventional columnar spacer formation position. FIG. 7A shows the arrangement of columnar spacers before pressurization in a cell gap forming step. 9B shows the positional variation of the columnar spacer due to the displacement of the substrate during wiping. Here, the columnar spacer SOC is fixedly formed on the inner surface of the upper substrate SUB2. As described above, the multi-layered structure film LY has irregularities (recesses are indicated by LYB and convex portions are indicated by LYT). The conventional columnar spacer SOC is likely to be located near the convex portion LYT of the multilayer structure film LY included in the lower substrate SUB1 as a portion avoiding the pixel region, particularly near the upper portion of the scanning wiring or the signal wiring.

In the process of assembling such a liquid crystal display device, liquid crystal is sealed between a pair of substrates as shown in FIG. 7A, and a predetermined cell gap is obtained through a pressurizing process for producing a cell gap. After setting, there is a step of wiping the surface with a cloth for cleaning. At this time,
When an external force is applied in a direction parallel to the substrate surface as indicated by arrows F1 and F2 in (b) and in a direction of pressing in the substrate surface direction, the columnar spacer SOC provided on the inner surface of the upper substrate SUB2.
Is slid down from the convex portion LYT of the multilayer structure film LY of the lower substrate SUB1 to the concave portion LYB.

After that, even if the external forces F1 and F2 are removed, the columnar spacer SOC is fitted in the concave portion LYB of the multilayer structure film LY and does not return to the previous convex portion LYT. Therefore, the positions of the upper and lower substrates deviate from a predetermined relationship and the set cell gap fluctuates, making it impossible to maintain desired display characteristics. This has been one of the problems to be solved in the past.

An object of the present invention is to solve the above-mentioned problems in the prior art and to suppress fluctuations in the inter-substrate position and cell gap caused by the fluctuations in the position of the columnar spacer due to the application of an external force to maintain desired display characteristics. Another object of the present invention is to provide the liquid crystal display device.

[0016]

In order to achieve the above object, the present invention provides a concave portion of a multilayer structure film having a top of a columnar spacer fixedly formed on one inner surface of a pair of substrates on the other substrate. It is characterized by being located. The typical configuration of the present invention is as follows.

At least one of a pair of substrates, a lower substrate and an upper substrate, has a multilayer structure film having an uneven surface formed of wiring and electrodes for forming pixels and one or more insulating layers on the inner surface of at least one of the substrates. A liquid crystal display device in which a liquid crystal is sealed in a bonding gap between the pair of substrates, the liquid crystal display device being fixedly formed on the inner surface of the lower substrate or the upper substrate and applied to the multilayer structure film of the opposing substrates. The columnar spacer is projected so as to have a contacting top, and the top of the columnar spacer is seated in the recess of the uneven surface of the multilayer structure film to suppress the movement of the pair of substrates in the substrate surface direction. did.

The present invention is not limited to the TN type thin film transistor type liquid crystal display device described in the above-mentioned prior art, and various modifications can be made without departing from the technical idea of the present invention. That is, what kind of liquid crystal display device can use at least the columnar spacer, and is a liquid crystal display device having a multilayer structure film having irregularities on at least the inner surface on the side where the top of the columnar spacer abuts? The same can be applied to a liquid crystal display device of any type or method.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings of the embodiments. FIG. 1 is a schematic cross-sectional view of the formation position of columnar spacers for explaining one embodiment of the liquid crystal display device of the present invention. In the figure, the lower substrate SUB
On the inner surface of 1, a multilayer structure film LY having a concavo-convex surface formed of wiring and electrodes for forming pixels and one or more insulating layers
Have. The convex portions of the multilayer structure film LY are indicated by LYT, and the concave portions are indicated by LYB. A multilayer structure film is also formed on the inner surface of the upper substrate SUB2, but the illustration is omitted.

The columnar spacer SOC for regulating the gap (cell gap) between the pair of substrates SUB1 and SUB2 is fixedly formed on the inner surface of the upper substrate SUB2 by the photolithography technique. And the columnar spacer SO
The top of C is the multilayer structure film LY of the lower substrate SUB1.
It is in a position to be seated in the recess LYB. The multilayer structure film LY is not limited to a portion formed by overlapping wirings, electrodes, and insulating layers, but is a portion having a stacked structure including only a plurality of insulating layers. By arranging the top of the columnar spacer SOC at such a position, the columnar spacer SOC returns to the original position even if the external force as described in FIG. 7 is applied. Therefore, the positional displacement between the upper and lower substrates does not occur, the cell gap does not change, and the desired display characteristics can be maintained.

FIG. 2 is a schematic sectional view of a columnar spacer forming position for explaining another embodiment of the liquid crystal display device of the present invention. In the figure, reference numeral L indicates wiring, and the same reference numerals as those in FIG. 1 correspond to the same functional portions. The present embodiment is particularly applied to a liquid crystal display device of a type in which one or both of scanning wirings and signal wirings per pixel have a multi-line structure in a multilayer structure film formed on the lower substrate SUB1. And
The columnar spacer S is provided in the recess formed between the electrodes L of the double-line structure.
The top of the OC is seated. Also in this embodiment, the columnar spacer SOC returns to the original position even when the external force described in FIG. 7 is applied. Therefore, the cell gap does not change, and desired display characteristics can be maintained.

FIG. 3 is a schematic plan view for explaining a specific example of the formation position of the columnar spacer in the liquid crystal display device of the present invention. Here, the columnar spacers SOC are arranged at the positions apart from the upper portions of the scanning wirings GL and the signal wirings DL and at the positions hidden by the black matrix BM of the multilayer structure film provided on the upper substrate SUB2. In FIG. 3, the columnar spacer SO
Although only three Cs are shown around one pixel, this is an example, and more columnar spacers S are provided at similar positions.
OC may be arranged. On the contrary, one columnar spacer SOC may be arranged for every plurality of pixels.

FIG. 4 is a schematic plan view for explaining another specific example of the formation position of the columnar spacer in the liquid crystal display device of the present invention. FIG. 4 shows, for example, Japanese Patent Laid-Open No. 2000-162646.
Scan electrodes GL and signal lines DL as disclosed in
The case where the columnar spacer SOC is arranged in the liquid crystal display device having the holding wiring HLHD in parallel with is described.
As shown in FIG. 4, when the wiring is formed in multiple lines around the pixel, a recess is formed between the multiple lines of the multilayer structure film formed on the lower substrate.

In this case, by arranging the top of the columnar spacer SOC in the recess formed between the above-mentioned double-line wirings, an external force is applied and the upper and lower substrates are moved in the substrate surface direction as described in the above embodiment. Even when the columnar spacer SOC is displaced, when the external force is removed, the columnar spacer SOC returns to the original position. Therefore, the relative positions of the upper and lower substrates are not displaced, the cell gap is not changed, and desired display characteristics can be maintained.

Although the columnar spacers are provided on the upper substrate or the color filter substrate side in each of the above embodiments, the columnar spacers may be provided on the lower substrate or the thin film transistor substrate side. The top may be seated in the recess of the multi-layered structure film which the upper substrate faces.

[0026]

As described above, according to the present invention,
By positioning the tops of the columnar spacers fixedly formed on one inner surface of the pair of substrates in the recesses of the multi-layered structure film on the other substrate, the cells caused by the position variation of the columnar spacers due to the application of external force It is possible to provide a liquid crystal display device that can suppress fluctuations in the gap and maintain desired display characteristics.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a formation position of a columnar spacer for explaining one embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a schematic cross-sectional view of a columnar spacer formation position for explaining another embodiment of the liquid crystal display device of the present invention.

FIG. 3 is a schematic plan view illustrating a specific example of the formation position of a columnar spacer in the liquid crystal display device of the present invention.

FIG. 4 is a schematic plan view illustrating another specific example of the formation position of the columnar spacer in the liquid crystal display device of the present invention.

FIG. 5 is a cross-sectional view illustrating an example of a main part structure of a TN type liquid crystal display device using a thin film transistor as a switching element.

FIG. 6 is a plan view of relevant parts for explaining an example of the installation position of columnar spacers in a conventional liquid crystal display device.

FIG. 7 is a cross-sectional view of relevant parts for schematically explaining a substrate displacement phenomenon caused by a conventional columnar spacer formation position.

[Explanation of symbols]

SUB1 ... Lower substrate, SUB2 ... Upper substrate, SOC ... Columnar spacer, LY ... Multilayer structure film, LYB ... Recessed portion, LYT ... Relieved portion, L・
···wiring.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshio Sato             Hitachi Device, 3681 Hayano, Mobara-shi, Chiba             Engineering Co., Ltd. (72) Inventor Masaaki Matsuda             Hitachi, Ltd. 3300 Hayano, Mobara-shi, Chiba             Factory Display Group F-term (reference) 2H089 LA09 NA15 QA14 TA02 TA09                       TA12

Claims (4)

[Claims] 1. A multi-layered structure film having a concavo-convex surface composed of wiring and electrodes for forming pixels and one or a plurality of insulating layers on the inner surface of at least one of a pair of substrates consisting of a lower substrate and an upper substrate. A liquid crystal display device having a liquid crystal enclosed in a bonding gap between the pair of substrates, the multilayer structure film of a substrate fixedly formed on an inner surface of the lower substrate or the upper substrate and facing each other. A columnar spacer that protrudes so as to have an apex that abuts against each other, and the apex of the columnar spacer is seated in the concave portion of the uneven surface of the multilayer structure film to move the pair of substrates in the substrate surface direction. A liquid crystal display device characterized in that 2. A thin film transistor and the thin film transistor are selectively turned on / off in a multilayer structure film formed on the lower substrate.
It has a scanning wiring for turning off, a signal wiring, and a pixel electrode, and a common electrode facing the pixel electrode, a color filter layer partitioned by a black matrix, and a columnar spacer are provided on the multilayer structure film formed on the upper substrate. The top of the columnar spacer is seated in a recess formed between the scanning wiring, the signal wiring, and the pixel electrode in the multilayer structure film of the lower substrate. Liquid crystal display device. 3. The scanning wiring and the signal wiring per pixel, which are included in the multilayer structure film formed on the lower substrate, each have a double-line structure, and the columnar spacers are formed in the recesses formed between the double-line structures. The liquid crystal display device according to claim 2, wherein the top is seated. 4. A thin film transistor and the thin film transistor are selectively turned on / off in a multilayer structure film formed on the lower substrate.
Scan line for turning off, signal line, pixel electrode and counter electrode, color filter layer partitioned by a black matrix in a multilayer structure film formed on the upper substrate, and columnar spacers, the lower substrate 2. The top of the columnar spacer fixedly formed on the upper substrate is seated in the concave portion between the scanning wiring, the signal wiring, and the pixel electrode included in the multilayer structure film. The described liquid crystal display device.