JP2001337323A - Reflection type liquid crystal display device, method for manufacturing the same, and portable appliance which uses the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device in which difference in brightness of display screen due to the difference in viewing angles is decreased and a display with uniform brightness is possible. SOLUTION: The reflection surface is constituted of a plurality of regions, and the depth of recesses and projections in each region is varied to generate different reflection characteristics of light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a reflection surface of a reflection type liquid crystal display device and a method of manufacturing the same.
The present invention also relates to a reflection surface of a reflection type liquid crystal display device of a portable information device such as a mobile phone, a portable information terminal or an electronic organizer, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A reflection type liquid crystal display device does not require a backlight as a light source, has characteristics of low power consumption, is lightweight and thin, and is used as a display device of a portable terminal device.

[0003] In order to obtain a bright display, a reflection type liquid crystal display device in which minute irregularities are formed on a reflection surface to reflect and scatter incident light is disclosed in JP-A-6-273800 and JP-A-8-273800. Japanese Patent Application Laid-Open No. 114797,
-153804, JP-A-11-28799
No. 0 is described in the specification.

FIG. 9 is a sectional view of a conventional reflection type liquid crystal display device. The incident light 51 incident from the light source 50 at an incident angle θi is reflected by the reflective electrode 60 of the reflective liquid crystal display device 33.
And becomes a regular reflection light 52a and a scatter reflection light 52b. The intensities of the specular reflection light 52a and the scattered reflection light 52b are as shown as arrows in the figure,
Good reflection characteristics with appropriate scattering can be obtained.

[0005]

The reflection characteristic of the reflection type liquid crystal display device shown in FIG. 9 is shown by a thick line S in FIG. FIG.
The case where the incident angle θi of the incident light 51 is 15 ° is shown.
The reflected light is specularly reflected light 5 in the direction of the light receiving angle θoa = 15 °.
The distribution has a peak at 2a.

Next, FIG. 11 shows the relationship between the direction of the reflected light and the position of the observer's eye.

[0007] Consider reflected light from positions α and β on the reflective electrode 60. The light receiving angle of the observer's eye 73 with respect to the position _α is θ _{o α} , and similarly, the light receiving angle of the observer's eye 73 with respect to the position β is θ _{o β} . The conventional reflection type liquid crystal display device 33 has a reflection surface having a reflection characteristic shown by a thick line S in FIG. 10 over the entire area of the display screen. Therefore, the intensity of the reflected light 71 that reaches the observer's eye 73 from the position α is point C on the vertical axis in FIG. 10, and the intensity of the reflected light 72 that reaches the observer's eye 73 from the position β is the vertical axis in FIG. And there is a great difference between the two. That is, in the conventional reflecting surface, the intensity of the reflected light 71, 72 received by the observer's eye 73 differs depending on the position on the display screen, and uniform brightness cannot be obtained on the entire display screen. In order to obtain uniform brightness, scattering by the reflecting surface may be strengthened and the reflection characteristics as shown by the thin line T in FIG. 10 may be obtained. However, there is a problem that the brightness of the entire display screen is reduced.

The present invention has been made to solve the above-mentioned problems, and has as its object to obtain a uniform and bright display on the entire display screen of a reflection type liquid crystal display device.

[0009]

SUMMARY OF THE INVENTION The present invention comprises an optical shutter means for controlling the amount of incident light transmitted by the electro-optic effect of a liquid crystal, and a reflecting surface for reflecting transmitted light transmitted through the optical shutter means. In the reflection type liquid crystal display device described above, the reflection surface is constituted by a plurality of regions having different light reflection characteristics.

Further, the present invention is characterized in that the reflecting surface is constituted by a plurality of regions divided in the vertical direction of the display screen, and the light reflection characteristics of each region are different.

The present invention also provides an optical shutter means for controlling the amount of incident light transmitted by the electro-optic effect of liquid crystal;
In a reflection type liquid crystal display device having a reflection surface for reflecting the transmitted light transmitted through the optical shutter means, the reflection surface is composed of a plurality of regions, and by changing the depth of the unevenness provided in each region, light is reflected. Are characterized by having different reflection characteristics.

The present invention is characterized in that the surface of the reflecting surface is constituted by arranging a plurality of regions having different light reflection characteristics in a ring shape.

According to the present invention, projections having different heights are formed on a substrate by using a photoengraving technique, and the projections are covered with an insulating film, and the insulating film is covered with a metal thin film to thereby form unevenness having different depths. And have different light reflection characteristics.

The present invention is characterized in that a reflection type liquid crystal display device having a reflection surface comprising a plurality of regions having different light reflection characteristics is mounted on a portable information device.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a sectional view showing a reflection type liquid crystal display device provided with a reflection surface according to Embodiment 1 of the present invention. The reflecting surface according to the present embodiment includes a plurality of regions having different light reflection characteristics.

In FIG. 1, a liquid crystal layer 10 is provided between a light transmitting substrate 3 and an insulating substrate 9 and
00. The retardation film 2 and the polarizing film 1 are provided on the surface of the liquid crystal display device 100 and on the transparent substrate 3.
Is provided. On the surface of the light-transmitting substrate 3 on the liquid crystal layer 10 side, a light-transmitting common electrode 4 and an alignment film 5 are provided. On the surface of the insulating substrate 9 on the liquid crystal layer 10 side, convex portions 11 and 12 made of an organic insulating film, an organic insulating film 8, a reflective electrode 7, and an alignment film 6 are provided in this order. By controlling the voltage applied to the reflective electrode 7 and the translucent common electrode 4, the alignment state of the liquid crystal molecules in the liquid crystal layer 10 is controlled, and the amount of light transmitted through the liquid crystal layer 10 is controlled by the electro-optic effect of the liquid crystal. . Light transmitted through the liquid crystal layer 10 is reflected by the reflective electrode 7.

The protrusions 11 and 12 made of an organic insulating film have different heights, and the height of the protrusion 11 is small and the height of the protrusion 12 is large. Therefore, the surface of the reflective electrode 7 provided via the organic insulating film 8 also has
12. Region 1 where convex part 11 is located
In 14, irregularities 14 formed on the surface of the reflective electrode 7
Is shallow. On the other hand, in the region 115 where the protrusion 12 is located, the unevenness 15 formed on the surface of the reflective electrode 7 is deep.

The relationship between the depth of the unevenness and the reflection characteristics will be described. Light scattering becomes stronger as the average inclination angle of the reflecting surface becomes larger. Therefore, unevenness 1 having the same size but different depths 1
In the case of providing the irregularities 4 and 15, the irregularities 14 having a small depth have a small average inclination angle and weak scattering, and the irregularities 15 having a large depth
Has a large average inclination angle and a strong scattering. That is, the reflection characteristics of the unevenness 14 and the reflection characteristics of the unevenness 15 have a relationship corresponding to the thick line S and the thin line T shown in FIG.

Therefore, the deep irregularities 15 having a large depth are formed at the position α in FIG. 11, and the small irregularities 14 are formed at the position β. The light receiving angle of the observer's eye 73 with respect to the position α is θ
_{o α} , similarly, the light receiving angle of the observer's eye 73 with respect to the position β is θ _{o β} , so the intensity of the reflected light 71 reaching the observer's eye 73 from the position α is point C on the vertical axis of FIG. The intensity of the reflected light 72 reaching the observer's eye 73 from the position β is also the point C on the vertical axis in FIG. 10, and both are almost equal. Therefore,
A display with uniform brightness can be obtained over the entire area of the display screen.

Referring to FIGS. 2 and 3, a method of manufacturing a reflection surface according to the present invention will be described.

First, as shown in FIG. 2A, a photosensitive organic insulating film 13 is formed on an insulating substrate 9 by spin coating. Here, "Nippon Synthetic Rubber PC-335" was used as the photosensitive organic insulating film, and was set at 600 rpm for 30 seconds.
Was spin-coated.

Next, as shown in FIG. 2B, the portions to be left as the protruding portions 11 and 12 are masked using a mask 18 and then exposed with light 19. Here, for example, when it is necessary to electrically connect the active element or the like to the reflective electrode 7, it is necessary to expose the photosensitive organic insulating film 13 in a portion to be a connection terminal hole.

Further, as shown in FIG. 2C, the photosensitive organic insulating film 13 is exposed with another mask 20 and light 21.
The exposure here is performed to adjust the height of the photosensitive organic insulating film 13 in a portion that will become the convex portion 11 later, and the light 21 has the desired thickness of the photosensitive organic insulating film 13. Is adjusted as follows.

When development and rinsing are performed and post-baking is performed, convex portions 11 and 12 having different heights as shown in FIG. 3A can be obtained.

As shown in FIG. 3B, an organic insulating film 8 is formed by spin-coating a photosensitive organic insulating film. Here, "Nippon Synthetic Rubber PC-3" was used as the photosensitive organic insulating film.
Using 35 ", spin coating was performed at 720 rpm for 30 seconds. Here, for example, when it is necessary to electrically connect the active element or the like and the reflective electrode 7, it is necessary to expose the organic insulating film 8 in a portion to be a connection terminal hole with a mask and light to perform development and rinsing. is there. Thereafter, post baking is performed.

As shown in FIG. 3C, a reflective metal 7 is formed by forming an aluminum metal thin film by a sputtering method. On the surface of the reflective electrode 7, irregularities 14 having a shallow depth corresponding to the convex portions 11 and irregularities 15 having a large depth corresponding to the convex portions 12 are provided.

The thickness of the photosensitive organic insulating film 13 and the mask 18
By changing the shape of the mask 20, the shape of the mask 20, and the intensity of the light 21, the projections 11 and 12 can be formed in a desired shape, height, and position. In addition, by appropriately selecting the film thickness and film quality of the organic insulating film 8, it is possible to obtain irregularities 14 and 15 having a desired shape, that is, a desired reflection characteristic.

Second Embodiment FIG. 4 is a diagram for explaining a second embodiment of the present invention.

FIG. 4 is a plan view of the reflection type liquid crystal display device of the present invention viewed from the observer's viewpoint. The upper part in the figure corresponds to the upper part of the reflective liquid crystal display device during use.

When the reflection type liquid crystal display device 100 is mounted on a portable terminal device such as a cellular phone and used, the viewpoint 73 of the observer is generally located below the screen of the liquid crystal display device as shown in FIG. . On the other hand, the incident light 70 from the light source is often incident obliquely from behind the observer. Therefore, the upper part of the display screen is a shallow uneven area 1 with little scattering.
14, and the lower part of the display screen is formed as a deep area 115 with a lot of scattering and unevenness, whereby a display screen with uniform brightness can be obtained.

Further, as shown in FIG. 6, the upper part of the display screen is a shallow uneven area 114 with little scattering, the lower part of the display screen is a deep uneven area 115 with much scattering, and the central part of the display screen is deep. However, it may be an intermediate region.

Further, as shown in FIG. 7, the display screen may be divided into a plurality of annular areas, and the unevenness may be deeper in the central area.

Third Embodiment FIG. 8 is a diagram showing a third embodiment of the present invention.

The portable telephone 39 shown in FIG.
0, and various function keys 41 such as power, hold, and redial, and a liquid crystal display section 42 for displaying a number, a message, and the like is provided further above the function keys 41.

As the liquid crystal display section 42, the reflection type liquid crystal display device having the reflection surface of the present invention is used, and a high quality display with uniform brightness can be obtained.

In the embodiment of the present invention, the example in which the reflective electrode is provided on the insulating substrate has been described. However, the present invention can be applied to an active element substrate using a TFT or the like.

In the embodiment of the present invention, aluminum is used as the material of the reflective electrode 7, but silver may be used, for example.

Although the embodiments of the present invention have been described with reference to a reflection type liquid crystal display device for monochrome display, a color liquid crystal display device may be provided by providing a color filter and a black matrix on the liquid crystal layer side of the translucent substrate 3.

[0040]

As described above, according to the present invention, since the surface of the reflection surface is constituted by a plurality of regions having different light reflection characteristics, the difference in the reflectivity in the display screen caused by the difference in the viewing angle. , And a favorable display with uniform brightness can be achieved.

Further, according to the present invention, light reflection characteristics are made different by providing irregularities having different depths on the surface of the reflection surface. Irregularities with different depths are formed by forming convex portions with different heights on the substrate using photoengraving technology, covering these convex portions with an insulating film, and covering the insulating film with a metal thin film. It can be easily formed using process technology.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a part of a reflective liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a method for manufacturing a reflection surface according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a method for manufacturing a reflection surface according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a reflective liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between a viewpoint of an observer and a reflection characteristic in the reflective liquid crystal display device according to the second embodiment of the present invention.

FIG. 6 is a diagram illustrating a reflective liquid crystal display device according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a reflective liquid crystal display device according to a second embodiment of the present invention.

FIG. 8 is a diagram for explaining Embodiment 3 of the present invention.

FIG. 9 is a diagram showing a relationship between incident light and reflected light in a conventional reflective liquid crystal display device.

FIG. 10 is a graph showing a reflection characteristic by a reflection surface.

FIG. 11 is a diagram showing a relationship between incident light and reflected light and the position of an observer's eye.

[Explanation of symbols]

1,53 polarizing film, 2,54 retardation film,
3, 55 translucent substrate, 4, 56 translucent common electrode,
5, 6, 57, 59 alignment film, 7, 60 reflective electrode, 8
Organic insulating film, 9, 62 Insulating substrate, 10, 58 Liquid crystal layer, 11, 12, 61 Convex portion, 13 Photosensitive organic insulating film, 14, 15 Unevenness, 16 Photosensitive organic photosensitive insulating film, 18, 20 Mask , 19, 21 light, 33 reflective liquid crystal display, 39 mobile phone, 40 numeric keypad,
41 function keys, 42 liquid crystal display device, 50 light source, 5
1, 70 incident light, 52a regular reflected light, 52b scattered reflected light, 71, 72 reflected light, 73 eye of observer.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinji Kawabuchi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Takao Sakamoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Rishi Electric Co., Ltd. F-term (reference) 2H042 BA04 BA15 BA20 2H091 FA16Y FB08 FD04 GA07 LA18 2H092 GA13 GA20 HA05 PA12 RA10

Claims (6)

[Claims] 1. A reflection type liquid crystal display device comprising: an optical shutter means for controlling a transmission amount of incident light by an electro-optic effect of a liquid crystal; and a reflecting surface for reflecting transmitted light transmitted through the optical shutter means. A reflection type liquid crystal display device, wherein the reflection surface comprises a plurality of regions having different light reflection characteristics. 2. A reflection type liquid crystal display device comprising: an optical shutter means for controlling a transmission amount of incident light by an electro-optic effect of a liquid crystal; and a reflection surface for reflecting transmitted light transmitted through the optical shutter means. 2. The reflection type liquid crystal display device according to claim 1, wherein the reflection surface is a plurality of regions divided in a vertical direction of the display screen, and each region has a different light reflection characteristic. 3. The reflection type according to claim 1, wherein the plurality of regions are regions having different light reflection characteristics by changing the depth of the unevenness provided in each region. Liquid crystal display. 4. The reflection type liquid crystal display device according to claim 1, wherein the plurality of regions are arranged annularly with respect to a center of a display screen. 5. A step of forming projections having different heights corresponding to the plurality of regions on a substrate by using a photoengraving technique;
2. The method according to claim 1, further comprising the steps of: covering the convex portion with an insulating film; and covering the insulating film with a metal thin film.
5. The method for manufacturing a reflective surface of a reflective liquid crystal display device according to 2, 3, or 4. 6. A portable information device comprising the reflection type liquid crystal display device according to claim 1, 2, 3 or 4.