JP2000267121A - Liquid crystal display - Google Patents

Abstract

(57) [Problem] To provide a liquid crystal display device capable of improving display performance. In a reflection type liquid crystal display device, a pixel electrode is provided.
The metal reflective film constituting the first organic insulating film 51 is further provided on the first organic insulating film 191 having a light-absorbing property.
2 are formed on at least two layers of insulating films. For this reason, the surface of the insulating film can be smoothed as compared with the case where the insulating film as the base of the pixel electrode 151 has only one layer.

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, and more particularly to a reflection type liquid crystal display having a reflection type pixel electrode.

[0002]

2. Description of the Related Art A reflection type liquid crystal display device comprises an array substrate having a switching element formed on one main surface and a pixel electrode formed by a metal reflection film, and a transparent conductive member such as indium tin. A counter electrode having a counter electrode formed of oxide, ie, ITO, and a liquid crystal composition sandwiched between these substrates. These substrates are fixed around the periphery thereof by a sealing material printed except for a liquid crystal sealing opening, and the liquid crystal sealing opening is sealed with a sealing agent. Further, around these substrates, an electrode transfer material for applying a voltage from the array substrate to the opposite substrate, that is, a silver paste as a transfer is arranged.

[0003] A reflective liquid crystal display device for color display is provided with a red, green, or blue color on an array substrate or a counter substrate.
It has a color filter that is colored in the three primary colors of blue or cyan, magenta, and yellow.

The pixel electrode is formed on an organic insulating film formed on the switching element, and is electrically connected to the switching element via a through hole formed in the organic insulating film.

[0005]

In the above-mentioned reflection type liquid crystal display device, since the pixel electrode as the reflection film is formed directly on the single-layer organic insulating film, the unevenness of the underlying organic insulating film causes It becomes difficult to smooth the surface of the pixel electrode. In a reflection type liquid crystal display device, when irregularities are formed on the surface of a pixel electrode as a reflection film, light incident from the counter electrode side is irregularly reflected. As a result, light irregularly reflected on adjacent pixels may cause a display defect such as color bleeding, or may cause a problem of lowering the brightness of each pixel.

Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a liquid crystal display device capable of improving display performance.

[0007]

In order to solve the above-mentioned problems and to achieve the object, a liquid crystal display device according to the first aspect of the present invention comprises a scanning line arranged in a row direction on one main surface, and a plurality of scanning lines. A signal line arranged in a column direction so as to be orthogonal, a switching element arranged at an intersection of the scanning line and the signal line, and a reflective pixel electrode electrically connected to the switching element. A liquid crystal display device comprising: one substrate; a second substrate having a counter electrode disposed on one main surface; and a liquid crystal composition sandwiched between the first substrate and the second substrate. The pixel electrode is formed on a light absorbing first organic insulating film formed on one main surface of the first substrate and a transparent second organic insulating film formed on the first organic insulating film. It is characterized by being formed.

According to the liquid crystal display device of the present invention, the pixel electrode is formed on at least two layers of the light absorbing first organic insulating film and on the transparent second organic insulating film. Have been. Therefore, the surface of the two-layer insulating film can be smoothed as compared with the case where the insulating film as the base of the pixel electrode has only one layer.

Therefore, the surface of the reflective film formed on the insulating film can be smoothed, and the light incident from the counter electrode can be reflected with good directivity without causing a decrease in reflectance. Become. As a result, it is possible to provide a liquid crystal display device which can solve the problems such as the occurrence of display defects and the decrease in luminance and can improve the display performance.

[0010] Further, by smoothing the surface of the insulating film serving as the base of the pixel electrode, pattern defects that may occur when patterning the reflective film can be reduced.

Further, when the insulating film has a two-layer structure, pinholes which may be generated when the insulating film is formed are reduced, and the reliability can be improved.

[0012]

Embodiments of a liquid crystal display device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view schematically showing one example of a liquid crystal display panel applied to the liquid crystal display device of the present invention.

A liquid crystal display device according to an embodiment of the present invention is a reflection type liquid crystal display device of an active matrix type, and includes a liquid crystal display panel 10 as shown in FIG.

As shown in FIG. 1, the liquid crystal display panel 10 has an array substrate 100 as a first substrate, an opposing substrate 200 as a second substrate disposed opposite to the array substrate 100, and an opposing substrate. A liquid crystal composition disposed between the substrate and the substrate. In such a liquid crystal display panel 10, a display area 1 for displaying an image is provided.
Numeral 02 is formed in a region surrounded by a seal material 106 for bonding the array substrate 100 and the counter substrate 200, and a peripheral area 104 having various wiring patterns drawn from the display area 102 is located outside the seal material 106. Area.

The display area 102 of the array substrate 100 is
As shown in FIGS. 2 and 3, mxn pixel electrodes 151 are arranged in a matrix on a transparent insulating substrate, for example, a glass substrate having a thickness of 0.7 mm.
M scanning lines Y1 to Y formed along one row direction
m, n signal lines X1 to Xn formed along the column direction of these pixel electrodes 151, and near the intersection of the scanning lines Y1 to Ym and the signal lines X1 to Xn corresponding to the mxn pixel electrodes 151. It has mxn thin film transistors or TFTs 121 arranged as non-linear switching elements, a scanning line driving circuit 18 for driving the scanning lines Y1 to Ym, and a signal line driving circuit 19 for driving these signal lines X1 to Xn.

The scanning lines are formed of a low-resistance material such as aluminum or a molybdenum-tungsten alloy. The signal line is formed of a low-resistance material such as aluminum, and is provided via an insulating film 113 formed on the glass substrate 101 and formed of a multilayer film of silicon oxide and silicon nitride.

The pixel electrode 151 is formed of a reflective film made of metal such as aluminum.

As shown in FIG. 3, the TFT 121 has a portion protruding from the scanning line as a gate electrode 112, and has a gate insulating film 113 laminated thereon. On the gate insulating film 113, a semiconductor film 115 formed of an amorphous silicon film, that is, an a-Si: H film is laminated.

The semiconductor film 115 is electrically connected to the pixel electrode 151 via the source electrode 131. Also,
The semiconductor film 115 is electrically connected to the drain electrode 132 extending from the signal line. The TFT 121 has a passivation film 1 made of an insulating film such as a silicon nitride film.
71.

On the passivation film 171, a light shielding film 191 functioning as a first organic insulating film is provided. On this light-shielding film 191, a transparent insulating film 192 as a second organic insulating film is provided.

The reflection film constituting the pixel electrode 151 is provided on the transparent second organic insulating film. This pixel electrode 1
51 denotes a passivation film 171, a first organic insulating film 1
It is electrically connected to the source electrode 131 of the TFT 121 via a through hole 195 penetrating the second organic insulating film 192 and the second organic insulating film 192.

As described above, the reflection film functioning as the pixel electrode 151 is formed on the light absorbing first organic insulating film 191.
Further, since the pixel electrode 15 is formed on at least two layers of the transparent second organic insulating film 192, the pixel electrode 15
Compared to a case where only one insulating film is used as a base,
The surface of the insulating film can be smoothed.

Therefore, the surface of the pixel electrode 151 formed on the second organic insulating film 192 can be smoothed, and the light incident from the counter substrate 200 can be made highly directional and the reflectivity can be reduced. It becomes possible to reflect without. As a result, problems such as occurrence of display defects and reduction in luminance can be solved, and display performance can be improved.

Further, by smoothing the surface of the insulating film 192 as a base of the pixel electrode 151,
Pattern defects that can occur when patterning the substrate can be reduced.

Further, by forming the insulating film into a two-layer structure, pinholes that may be generated when the insulating film is formed are reduced, and the reliability can be improved.

The surface of the pixel electrode 151 is
Are covered with an alignment film 141 for aligning the liquid crystal composition 300 interposed between the liquid crystal composition 300 and the liquid crystal composition 300.

Each of the thin film transistors 121 has a corresponding one of the signal lines X1 to Xn driven by the signal line driving circuit 19 when the corresponding scanning line is driven by the scanning line driving circuit 18 to select the pixel electrode 151 in the corresponding row. It is used as a switching element for applying a potential to the pixel electrodes 151 in the corresponding rows.

The scanning line driving circuit 18 supplies a scanning voltage to the scanning lines Y1 to Ym sequentially in a horizontal scanning cycle, and the signal line driving circuit 19 supplies a pixel signal voltage to the signal lines X1 to Xn in each horizontal scanning cycle. I do.

In the liquid crystal display panel 10, as shown in FIG. 1, although not shown in detail in order to reduce the external dimensions of the liquid crystal display device, particularly, the frame size, signal lines are formed around the array substrate 100. The X-TAB 401-is pulled out only to the first end side 100X side of the area 104X and is connected to the X control circuit board 421 including the signal line driving circuit 19 for supplying video data to the signal lines on the first end side 100X side.
1, 401-2, 401-3, and 401-4.

The scanning lines are also drawn out only to the second side 100Y of the peripheral area 104X of the array substrate which is orthogonal to the first side 100X, and a scanning pulse is supplied to the scanning lines at the second side 100Y. The Y-TAB 411- is mounted on the Y control circuit board 431 including the scanning line driving circuit 18 and the like.
1, 411-2.

The display area 10 of the array substrate 100
2 and non-pixel portions in the peripheral area 104 (X, Y),
That is, as shown in FIG. 3, a gap having a predetermined width is formed between the array substrate 100 and the counter substrate 200 on the wiring patterns such as the signal lines 103 and the scanning lines 111, the TFT 121, the pixel electrode 151, the peripheral frame portion, and the like. A spacer 400 to be formed is arranged. This spacer 400
Has a height of 5 μm and is formed of a single layer of resin having a column shape of 10 μm square.

As a result, the gap between the array substrate 100 and the counter substrate 200 is set to about 5 μm.

As shown in FIG. 3, the display area 102 of the counter substrate 200 has a transparent insulating substrate, for example, having a thickness of 0.1 mm.
A color filter 203 is provided on a 7 mm glass substrate 201. This color filter 203
It is a region facing the pixel electrode 151 of the counter substrate 200, and is arranged in a region corresponding to each of a red pixel (R) region, a green pixel (G) region, and a blue pixel (B) region. The color filter 203 is formed of, for example, a resin in which pigments of each color component are dispersed.

The surface of the color filter 203 is formed of a transparent conductive member which forms a potential difference with the pixel electrode 151,
For example, indium-tin-oxide or ITO
Is covered by the counter electrode 204 formed by the above. The surface of the counter electrode 204 is
00 is covered with an alignment film 205 for aligning the liquid crystal composition 300 interposed therebetween.

The counter electrode 204 includes a plurality of pixel electrodes 151.
Are set to the reference potential. An electrode transfer material, that is, a silver paste as a transfer, disposed around the substrate is provided to supply a voltage from the array substrate 100 to the counter substrate 200, and the counter electrode 204 is connected to the counter electrode drive connected via the transfer. Driven by the circuit 20.

The liquid crystal capacitance CL is formed by the liquid crystal layer 300 sandwiched between the pixel electrode 151 and the counter electrode 204.

The array substrate 100 includes a pair of electrodes for forming an auxiliary capacitance CS electrically in parallel with the liquid crystal capacitance CL. That is, the storage capacitor CS is connected to the pixel electrode 15
1 is formed by a potential difference formed between the storage capacitor electrode 61 having the same potential as 1 and the storage capacitor line 52 set to a predetermined potential.

On the front and back surfaces of the liquid crystal display panel 10, that is, on the outer surface of the glass substrate 201, a polarizing plate having a deflecting surface selected according to the display mode of the liquid crystal display device and the twist angle of the liquid crystal composition is required. It is arranged according to.

Next, a method of manufacturing the liquid crystal display device shown in FIG. 3 will be described.

That is, the scanning lines Y and T are placed on a 0.7 mm thick # 1737 glass substrate 101 manufactured by Corning.
Aluminum, molybdenum-tungsten alloy, gate insulating film 113 for forming gate electrode 112 of FT 121
, A multilayer film of a silicon oxide film and a silicon nitride film, an amorphous silicon film 115 as a semiconductor film of the TFT 121, aluminum for forming the signal line X, the source electrode 131 and the drain electrode 132, and a silicon nitride film for forming the passivation film 171. Are formed and patterned.

As a result, a plurality of scanning lines Y arranged in a row direction on one main surface of the glass substrate 101, and the scanning lines Y
The signal lines X, the switching elements 121 arranged at the intersections of the scanning lines Y and the signal lines X, and the passivation film 171 covering these are formed.

Subsequently, the passivation film 171 has T
A through hole 195 penetrating through the source electrode 131 of the FT 121 is formed.

Subsequently, on the passivation film 171,
A light absorbing first organic insulating film 191 is formed. That is, a photosensitive carbonless black resin containing an organic pigment is coated on one main surface of the array substrate 100 by using a spinner.
Coat with a thickness of 0 μm and dry at 90 ° C. for 10 minutes. Thereafter, the photosensitive resin was applied at a wavelength of 365 nm to 300 mJ / cm using a photomask having a predetermined pattern shape.
After the exposure with the exposure amount of ² , development is performed with an aqueous alkaline solution having a pH of 11.5. Then, by baking at 200 ° C. for 60 minutes, a first organic insulating film 191 as a light-shielding film having a thickness of 2.0 μm is formed.

At this time, a through hole 195 penetrating through the source electrode 131 of the TFT 121 is formed at the same time.

In this embodiment, the first organic insulating film 191 is made of a black photosensitive resin, but may be blue as long as the light absorbing property is sufficient.

Subsequently, a transparent second organic insulating film 192 is formed on the first organic insulating film 191. That is, a photosensitive transparent resin is applied on one main surface of the array substrate 100 with a thickness of 2.0 μm using a spinner, and dried at 80 ° C. for 2 minutes. After that, the photosensitive resin is coated with a photomask having a predetermined pattern at a wavelength of 365 nm and a thickness of 50 nm.
After exposure at an exposure of 0 mJ / cm ² , pH 11.5
Develop with an aqueous alkali solution. And 200 ° C
For 60 minutes to form a second organic insulating film 192 as a transparent insulating film having a thickness of 1.5 μm.

At this time, a through hole 195 penetrating through the source electrode 131 of the TFT 121 is formed at the same time.

Subsequently, a metal reflection film, that is, a pixel electrode 151 is formed on the second organic insulating film 192. That is, aluminum is formed on one main surface of the array substrate 100 by a sputtering method. At this time, the through hole 195 is also filled with aluminum, and is electrically connected to the source electrode 131 of the TFT 121. Thereafter, the aluminum thin film is patterned into a predetermined pixel electrode shape. Thus, a reflective pixel electrode 151 is formed.

Subsequently, an acrylic negative resist is applied on one main surface of the array substrate 100, and is applied with a wavelength of 365 nm at a wavelength of 365 nm through a photomask having a predetermined pattern shape.
After exposure at an exposure amount of 0 mJ / cm ² , development is performed with TMAH, that is, an aqueous solution of tetramethylammonium hydroxide for 50 seconds, and baking is performed to form a columnar spacer 400 at a predetermined position.

Subsequently, an alignment film 141 is formed by applying polyimide as an alignment film material over the entire surface and performing a rubbing process.

On the other hand, a color filter 20 was placed on a Corning # 1737 glass substrate 201 having a thickness of 0.7 mm.
3. The counter electrode 204 and the alignment film 205 are respectively formed, and the counter substrate 200 is formed.

In this embodiment, the counter substrate 20
Although the color filter 203 is provided on the 0 side, the array substrate 1
It may be provided on the 00 side.

Subsequently, the sealing material 106 is printed along the periphery of the alignment film 205 of the counter substrate 200 except for the liquid crystal injection port. Further, from the array substrate 100 side, the counter substrate 20
An electrode transfer material for supplying a voltage to the 0-side counter electrode 204 is formed on the electrode transfer electrode around the seal member 106.

Subsequently, the glass substrates 101 and 201 are arranged so that the alignment films 141 and 205 face each other.
Heat is applied to cure the sealing material 106, and the two substrates are bonded to each other.

Subsequently, the liquid crystal composition 30 was injected through the liquid crystal injection port.
A reflection type liquid crystal display device is formed by injecting a mixture obtained by adding 0.1 wt% of chiral agent S811 to ZLI-1565 (manufactured by E. Merck) as 0, and sealing the liquid crystal injection port with an ultraviolet curing resin. I do.

In the reflection type liquid crystal display device manufactured as described above, the insulating film serving as the base of the reflective pixel electrode is formed of at least two insulating films made of a light absorbing organic insulating film and a transparent organic insulating film. Thus, the surface of the insulating film can be smoothed, and the surface of the pixel electrode itself can be smoothed. Therefore, it is possible to reflect light incident from the counter electrode side with good directivity and without lowering the reflectance.

Further, since the gap formed between the reflective pixel electrodes is shielded from light by the light-absorbing organic insulating film, it is possible to prevent light from leaking between the pixels and always perform black display. Become.

As a result, it is possible to provide a liquid crystal display device which can solve the problems such as the occurrence of display defects and the decrease in luminance and can improve the display performance.

[0060]

As described above, according to the present invention, it is possible to provide a liquid crystal display device capable of improving display performance.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing an example of a liquid crystal display panel applied to a liquid crystal display device of the present invention.

FIG. 2 is a diagram schematically showing a configuration of a liquid crystal display device of the present invention.

FIG. 3 is a sectional view schematically showing a structure of the liquid crystal display device of the present invention.

[Explanation of symbols]

 Reference Signs List 10 liquid crystal panel 100 array substrate 121 thin film transistor 151 pixel electrode 191 first organic insulating film 192 second organic insulating film 195 through hole 200 counter substrate 204 counter electrode 300 liquid crystal composition 400 spacer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H092 JA26 JA29 JA35 JA36 JA38 JA42 JA44 JA46 JB13 JB23 JB32 JB33 JB38 JB52 JB57 JB63 JB69 KA05 KA07 KA12 KA16 KA18 KB25 MA05 MA08 MA14 MA15 MA16 MA18 MA19 MA35 MA32 NA19 NA25 NA29 PA12

Claims (8)

[Claims] 1. A scanning line arranged in a row direction on one main surface, a signal line arranged in a column direction orthogonal to these scanning lines, and arranged at an intersection of the scanning line and the signal line. A first substrate having a switching element and a reflective pixel electrode electrically connected to the switching element; a second substrate having a counter electrode disposed on one principal surface; A liquid crystal composition sandwiched between two substrates, wherein the pixel electrode comprises: a light-absorbing first organic insulating film formed on one main surface of the first substrate; A liquid crystal display device formed above the first organic insulating film and the second organic insulating film. 2. The liquid crystal display device according to claim 1, wherein the first organic insulating film contains an organic pigment. 3. The liquid crystal display device according to claim 1, wherein the first organic insulating film is black. 4. The liquid crystal display device according to claim 1, wherein the first organic insulating film is blue. 5. The liquid crystal display according to claim 1, wherein the first organic insulating film is transparent. 6. The liquid crystal display device according to claim 1, wherein the second substrate includes a color filter formed on one main surface. 7. The device according to claim 1, wherein the first substrate includes a color filter formed on the pixel electrode.
3. The liquid crystal display device according to 1. 8. The liquid crystal display device, wherein the first substrate and the second substrate
2. The liquid crystal display device according to claim 1, further comprising a columnar spacer for forming a predetermined gap between the substrate and the substrate.