JP2001305534A - Reflector and reflective display element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve pattern deviation and to enhance productivity when a rugged structure of a reflecting layer of a reflection type liquid crystal display element is formed from a plurality of layered patterns. SOLUTION: The rugged structure of the reflecting layer 106 is composed by making a plurality of belt-like projecting parts 102...103, etc., into a mesh shape. By making the projecting parts 102...103, etc., into the mesh shape, even if pattern deviation is generated in an upper and lower layer, a convex shape of an intersection point does not change but uniform reflexivity is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a reflection plate and a reflection type display device capable of realizing high luminance.

[0002]

2. Description of the Related Art With the rapid spread of mobile terminals and the like, reflective panels are receiving attention. As a technique for increasing the brightness of the reflective panel, a scattering reflector having an uneven structure on the surface of the reflective layer has been proposed (Japanese Patent Laid-Open No. Hei 5-232465). A stacked configuration was used.

Japanese Patent Application Laid-Open No. H11-258596 discloses a method of forming a concavo-convex structure using a process of forming a TFT element and a peripheral wiring in order to reduce the number of production steps. An uneven structure was formed by laminating a plurality of columnar projections.

[0004]

In order to increase the brightness of the panel, it is important to control the uneven structure. The average inclination angle distribution of the inclined surface of the uneven structure is a maximum of about 6 ° to 15 °. Need to design.

Conventionally, after a flattening layer is formed on an array substrate, one convex portion is formed with a photosensitive resist, and further, a flattening layer whose shape is changed by thermal annealing is laminated to control the shape.

As described above, conventionally, a TFT is provided on an array substrate.
Since the peripheral wiring such as an element, a gate, and a source is formed and then a resist is laminated, the manufacturing process is complicated and there is a problem in productivity (Japanese Patent Laid-Open No. Hei 5-232465).

On the other hand, when a concavo-convex structure is formed by using a process for forming a TFT element and a peripheral wiring (11-25)
No. 8596), it is necessary to laminate a plurality of convex portions depending on the process. However, misalignment of the mask is inevitably caused during the manufacturing. Therefore, if independent columnar projections are used, the projections are not evenly stacked, and it is difficult to obtain a desired uneven structure.

[0008]

Means for Solving the Problems In order to solve the above problems, the present invention takes the following measures in a display element having a reflective layer having an uneven structure.

That is, the invention according to claim 1 is a reflection plate, comprising a substrate and a reflection layer having an uneven structure formed on the substrate, wherein the uneven structure is provided on the substrate. It is characterized by being formed by a plurality of formed strip-shaped thin film patterns crossing each other.

According to a second aspect of the present invention, there is provided the reflector according to the first aspect, wherein convex portions are laminated at intersections where the thin film patterns intersect each other.

With the above structure, the strip-shaped thin film patterns are configured to intersect each other, so that a desired uneven structure can be obtained. If a vertex is formed, a more desired uneven structure can be obtained.

According to a third aspect of the present invention, there is provided the reflector according to the first aspect, wherein the shape of the intersection where the thin film patterns intersect each other is a concave portion.

With the above-described configuration, a desired uneven structure can be obtained.

According to a fourth aspect of the present invention, there is provided the reflector according to the first aspect, wherein the thin film pattern has a mesh shape.

As described above, when the thin film pattern has a mesh shape, even if the strip-shaped thin film pattern is displaced between the upper and lower layers due to misalignment of the mask or the like, the intersection point moves only slightly, but the intersection of the thin film pattern does not move. The shape itself is kept substantially constant. Therefore, even if a mask shift occurs, the reflection plate can exhibit substantially uniform reflection characteristics, and productivity is greatly improved.

According to a fifth aspect of the present invention, there is provided the reflector according to the first aspect, wherein an interval between the thin film patterns is not constant.

According to the above configuration, by setting the interval between adjacent strip-shaped thin film patterns at random, diffraction and interference of reflected light are suppressed, and a good display is obtained.

The invention according to claim 6 is the reflector according to claim 1, wherein an active element is further formed on the substrate, and the thin film pattern is formed by a thin film constituting the active element. It is characterized by being formed.

The invention according to claim 7 is the reflector according to claim 1, wherein an active element is further formed on the substrate, and the thin film pattern is formed by a step of forming the active element. It is characterized by being formed simultaneously.

With this configuration, the strip-shaped thin film pattern can be formed by using a process for forming the TFT elements on the array substrate and the peripheral wiring, and in this case, the productivity is further improved. .

According to an eighth aspect of the present invention, there is provided a reflection type display device, wherein the reflection plate according to any one of the first to seventh aspects, and a light control means provided on the reflection plate for controlling a light absorption amount. , Is characterized by having.

By adopting the above-described structure, the productivity of the reflective display device is greatly improved, and a low-cost, high-brightness reflective display device can be realized.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a reflection type display device (reflection type liquid crystal display device) of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a top view of an array substrate 110 constituting a liquid crystal display device according to Embodiment 1. FIG. The reflection layer 106 is formed on the gate line 100 and the source line 101.

Below the reflective layer 106, a first convex portion 102 and a second convex portion 103, which are thin film patterns, are formed in a mesh shape crossing each other. In addition, concave portions 104 exist between the meshes. Also, the mesh spacing is random, so that light diffraction, interference and the like do not occur.

The first convex portion 102 and the second convex portion 1
At the intersection with 03, two layers are stacked to form the highest convex intersection 107 on the reflection surface. FIG. 2 is a conceptual diagram showing where the first convex portion 102 and the second convex portion 103 intersect. Two layers are stacked at the convex intersection point 107, and the step becomes the largest.

Then, as shown in FIG. 3, after a planarizing layer 108 is laminated on the same structure, and a reflective layer 106 is provided on the planarizing film 108, the convex and concave portions are smoothly formed by the planarizing layer 108. Thus, an uneven structure is formed around the peaks 107 and the recesses 104, and the unevenness of the reflective layer 106 is formed.

When the convex portion of the reflecting surface is formed as a band-shaped convex portion as described above, and a plurality of layers are laminated and formed in an intersecting shape, the intersection of the highest convex portion from the reflecting surface must be 10 at the intersection.
7 is formed. In this configuration, even if the mask is misaligned, the shape of the intersection of the convex portions is kept substantially the same, and the productivity is improved. For example, with respect to the first convex portion 102, the second convex portion 10 in the upper layer
Consider a case where 3 moves rightward in FIG. 1 due to misalignment. At this time, since the position of the convex intersection 107 does not change, the reflection performance is the same. Further, even if it shifts upward, the intersection of the convex portions only shifts upward as a whole, and the reflection performance of the entire reflecting surface is almost the same. Therefore, defects due to misalignment of the mask are greatly reduced, and productivity is improved.

FIG. 4 is a diagram showing another embodiment of the first embodiment. The first and second convex portions 112 and 113 are characterized by being formed in a belt shape formed of a curved line. When the convex portion is curved, the shape of the concave portion 114 is particularly diversified, so that desired reflection characteristics can be more easily realized. This is because if the shape of the concave portion is various, it becomes easier to control the inclination angle distribution after the flattening layer is laminated. Further, even if the convex portion is formed by a curved line, the first convex portion 112 and the second convex portion 113 are formed.
If the ridges do not intersect with each other, the reflection performance will be substantially the same even if a mask shift occurs as described above. Further, when the convex portions are curved, diffraction and interference of reflected light are less likely to occur. This is because the contrast of the belt-shaped convex portion in the vertical, horizontal, and oblique directions is significantly reduced.

Naturally, if the interval between the convex portions is made random, an effect that diffraction and interference of the reflected light are more unlikely to be obtained can be obtained.

Next, a specific example of the first embodiment of the present invention will be described.
This will be described with reference to FIGS.

Using a process for forming a TFT element, a gate wiring, a source wiring and the like on an array substrate,
Protrusions were formed on the substrate 110. At this time, the first convex structure 102 is formed to have a width of 1 by using the same process as that for forming the gate oxide film.
It was formed in a stripe shape of 0 μm and 0.5 μm in height. Next, the second convex structure 103 was formed in a stripe shape having a width of 10 μm and a height of 0.5 μm by using the same process as the formation of the source wiring. At this time, two layers were stacked at the projection intersection, and the step was 1 μm. When the belt-like convex portions are formed using the same material as the TFT element and the peripheral wiring by using the process of preparing the array substrate, the manufacturing process is simplified and the productivity is improved.

Next, a flattening layer 108 was laminated with a layer thickness of 0.5 μm, the shape was melted by thermal annealing to a desired inclination angle, and then a reflective layer 106 was formed using Al. At this time, the average inclination angle of the reflective layer 106 was about 11 ° at the maximum.

A liquid crystal display device was prepared using the array substrate and the counter substrate. The reflectivity of the device was 36%, and a high-luminance panel was realized.

In order to examine a margin for mask alignment, the reflectance at the time of forming the second convex structure 103 was intentionally shifted, and the reflectance was compared with that of the related art.

In the case of the conventional columnar convex portion, the first convex structure 10
In the case where the diameter of No. 2 was 10 μm, if the deviation was 2 μm or more, the columnar shape became asymmetric, and as a result, a desired inclination angle distribution could not be obtained. For this reason, the reflection performance was greatly reduced. In addition, since the displacement was different in the panel, luminance unevenness occurred in the panel.

Further, when a large-sized glass substrate is formed on a production line, the mask shift is further increased at the position of the panel piece in the glass, and a panel having the same display performance cannot be obtained.

On the other hand, according to the structure of the present invention, even if the mask position is shifted by about 10 μm, only the position of the convex intersection 107 moves, but the reflection performance is almost the same. As a result, productivity has been greatly improved.

The convex structure can be formed not only in the above-mentioned example but also in combination with the formation of an arbitrary layer in the array process. For example, it may be used also as an a-Si layer. The number of layers may be two or more.

The same display performance can be obtained by forming a planarization layer on a source, a gate, and the like without using the array process, and then forming a projection using a photosensitive resist.

The convex structure may have a curved structure shown in FIG. 4 or a mixture of a stripe and a curve in addition to the above-mentioned stripe structure. For example, if the inside of the pixel is a curve and only the vicinity of the contact hole 105 is a stripe configuration, the convex portions can be efficiently arranged. Further, in the case of a curved configuration, the convex portions can be efficiently arranged even if the shape of the contact hole 105 is configured by a curve according to the adjacent curved configuration. Efficiently arranging the convex portions reduces the flat region having a small inclination angle and improves the reflectance.

The thickness of the flattening layer can be formed to be about 2 μm or less in addition to the above-mentioned 0.5 μm. The layer thickness can be arbitrarily selected according to the size of the maximum step of the convex portion, the size and shape of the concave portion, and the top shape of the convex portion.

In the above example, the reflection type liquid crystal display device has a reflection layer formed on the entire surface. However, this may be a transflective type liquid crystal display device having an opening window in the reflection layer. At this time, the shape of the opening window can be efficiently arranged by changing the contour according to the configuration of the adjacent band-shaped convex portion in addition to the circular, square, or rectangular shape.

In the above example, the concavo-convex structure is formed using the band-shaped convex portions. However, a concavo-convex structure having a configuration as shown in FIG. 5 may be used. FIG. 5A is a conceptual diagram showing another configuration of the array substrate, and FIG. 5B is a partial cross-sectional view of FIG. 5A. That is, for example, a gate insulating film 121 is formed on the substrate 120, and the gate insulating film 121 is formed into a matrix by using photolithography and etching techniques.
(Having the band-shaped concave portions 121b ...). Also, a band-shaped convex portion and a concave portion may be used in combination.

In the above example, the concavo-convex structure is formed by combining the band-shaped protrusions, but this may include a concavo-convex structure having a shape other than the band-shaped protrusions. For example, an independent convex portion may be formed in the concave portion. If there are more independent projections (for example, columnar and polygonal columns) in the recesses, the inclination angle of the recesses can be more easily controlled, and the reflectance can be improved.

Further, the belt-shaped convex portions need not necessarily be continuous, and may have a partially cut structure. If the deviation is small in accordance with the expected mask deviation, a similar effect can be obtained even if the belt-shaped convex portion is formed in a cross shape from the center of the convex portion around the standard intersection position.

(Embodiment 2) A reflection type liquid crystal display device is obtained by adding a backlight system, a drive circuit section, a housing and the like to the liquid crystal display element of Embodiment 1.

By forming the intervals of the convex portions at random, a favorable display without coloring and without generation of diffraction or interference terms was obtained.

(Embodiment 3) The same structure as that of the reflection layer used in the liquid crystal display element of Embodiment 1 was formed on a substrate to form a reflection plate. With this configuration of the reflector, even when a plurality of protrusions or recesses are laminated to form a concavo-convex structure, a pattern displacement due to mask displacement does not occur, and a scattering reflector having uniform reflection performance even in a large area can be obtained. Was done.

(Other Matters) In the above embodiment, the reflection type liquid crystal display device using liquid crystal was described. However, the reflection type display device of the present invention is not limited to the display device using liquid crystal. . For example, it can be applied to an electrophoretic display that controls light absorption and transmission by moving fine particles dispersed in a solution by an electric field, and can be used for a reflective display element other than a liquid crystal display element. Can be.

[0051]

As described above, according to the present invention, when a plurality of band-shaped convex portions having intersections are used as the concave-convex structure of the reflective layer, the reflection due to the pattern shift when the plural layers are laminated to form the concave-convex structure. The rate fluctuation is eliminated and productivity is greatly improved.

[Brief description of the drawings]

FIG. 1 is a top view of an array substrate constituting a liquid crystal display element according to a first embodiment.

FIG. 2 is a conceptual diagram of a concavo-convex structure on an array substrate.

FIG. 3 is a partial sectional view of the array substrate.

FIG. 4 is a top view of another configuration of an array substrate constituting the liquid crystal display element according to the second embodiment.

FIG. 5 is a conceptual diagram showing another configuration of the array substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 Gate line 101 Source line 102 1st convex part 103 2nd convex part 104 concave part 105 contact hole 106 reflective layer 107 convex part vertex 108 planarization film 110 board 112 1st convex part 113 2nd convex part 114 concave part 116 reflection layer 117 convex part vertex 120 substrate 121a convex part 121b concave part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Naohide Wakita 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 2H042 BA03 BA15 BA20 DA02 DA22 DB01 DC00 DC08 DD01 DE00 2H091 FA16Z FA34Z FC01 FD06 GA13 LA12

Claims (8)

[Claims] 1. A substrate comprising: a substrate; and a reflective layer having an uneven structure formed on the substrate, wherein the uneven structure is such that a plurality of strip-shaped thin film patterns formed on the substrate intersect with each other. A reflecting plate characterized by being formed by: 2. The reflector according to claim 1, wherein convex portions are laminated at intersections where the thin film patterns intersect each other. 3. The reflector according to claim 1, wherein the shape of the intersection where the thin film patterns intersect each other is a recess. 4. The reflector according to claim 1, wherein the thin film pattern has a mesh shape. 5. The reflector according to claim 1, wherein an interval between the thin film patterns is not constant. 6. The reflector according to claim 1, wherein an active element is further formed on the substrate, and the thin film pattern is formed by a thin film constituting the active element. 7. The reflector according to claim 1, wherein an active element is further formed on the substrate, and the thin film pattern is formed simultaneously by a step of forming the active element. . 8. A reflection-type display device, comprising: the reflection plate according to claim 1; and light control means provided on the reflection plate for controlling an amount of light absorbed.