JP2003270625A - Reflection type liquid crystal display device, method of manufacturing the same, and portable apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device which obtains a bright display image in a prescribed angular range. <P>SOLUTION: The reflection type liquid crystal display device is provided with a liquid crystal layer, first and second electrodes for applying a voltage to the liquid crystal layer, and a reflection plate arranged on the side being the rear side of the liquid crystal layer when observed, and the reflection plate has many rectangular main slopes 1a, 1b, and 1c inclined in a specific direction arranged at prescribed intervals, of which the main slopes 1a and 1b and the main slopes 1a and 1c adjacent in a direction crossing the inclination direction x are shifted from each other in the inclination direction, and is provided with auxiliary slopes 2b and 2c for connecting main slopes adjacent in the direction crossing the inclination direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal display device and a method for manufacturing the same. The present invention also relates to a mobile device such as a mobile phone, a personal digital assistant, an electronic notebook, etc., which is equipped with the reflective liquid crystal display device.

[0002]

2. Description of the Related Art Reflective liquid crystal display devices have been installed as display devices for mobile devices such as mobile information terminals and mobile phones, which are required to display bright images with low power consumption, and have recently been required to have higher performance. Has been done.

The conventional problems of the reflection type liquid crystal display device are that it is difficult to see the original image due to the influence of an unintended reflection component such as regular reflection from the surface of the liquid crystal display device to the viewing direction.
There was a point that the displayed image was dark. As a method of improving the former, it is known that random unevenness is created on the surface of the reflection plate and diffuse reflection is performed at a wide angle in the reflection direction of the image, but it is difficult to improve the latter with this method. Was known. As a method of improving the latter, it is known to form a reflector having an asymmetrical shape.

FIG. 14 is a diagram showing the shape of a conventional reflector disclosed in Japanese Patent Laid-Open No. 9-80426. FIG. 14A shows the cross section of the reflector, and FIG. 14B shows the surface. In FIG. 14, 101 is a reflector,
101a is a protrusion, 102 is a substrate, α is the inclination angle of the protrusion inclined surface on the upper side of the panel (reflector 101) in use, β
Is the inclination angle of the protrusion inclined surface which is the lower side of the panel when in use.

As shown in FIG. 14B, this reflector 1
A large number of fan-shaped convex portions 101 a are formed on the surface of 01. As shown in FIG. 14A, the apex of the convex portion 101a is unevenly distributed in the lower part of the panel in the used state, and both upper and lower side surfaces thereof are inclined. In use, the inclination angle α of the inclined surface on the panel upper side is smaller than the inclination angle β of the inclined surface on the panel lower side, and the inclined surface on the panel upper side is inclined more gently than the inclined surface on the panel lower side. ing.

In Japanese Patent Application Laid-Open No. 9-80426, FIG.
A stripe-shaped convex portion 101a having a cross section of (a)
There is also disclosed a reflecting plate formed so as to extend parallel to the left and right sides of the panel when in use.

By using these reflectors, it is possible to fabricate a reflection type liquid crystal display device capable of concentrating the direction of reflected light in a specific direction and displaying a bright image.

A method of manufacturing these reflectors will be described with reference to FIG. FIG. 15 is a diagram showing a conventional method for manufacturing a reflector, and such a manufacturing method is disclosed in, for example, Japanese Patent Laid-Open No. 10-1.
It is disclosed in Japanese Patent No. 77106. In FIG.
Reference numeral 115 denotes a reflector, 111 denotes a glass substrate, and 112.
Is a resist film, 112a is a convex portion, 113 is a photomask, 114 is a metal thin film, and Q is light exposure.

In FIG. 15A, a resist film 112 is formed on the glass substrate 111. Next, as shown in FIG. 15B, a photomask 113 was set, and exposure and development were performed to form a striped resist film 112 shown in FIG. 15C. After that, as shown in FIG. 15D, the glass substrate 111 is tilted and heat treatment is performed. By the heat treatment, as shown in FIG. 15 (e), a smooth and asymmetric convex portion 112a having a bias in the distribution of the inclination angle is obtained. A metal thin film 114 was formed on the surface in FIG.

By using this method, a reflector having an asymmetric inclination angle distribution can be manufactured relatively easily.

[0011]

The conventional reflection plate is constructed as described above, and a stripe-shaped convex portion 101a having a cross section of FIG. 14A is used as a reflection plate of a reflection type liquid crystal display device. When using a reflector that is formed so as to extend parallel to the left and right sides of the panel in use, it is possible to concentrate the direction of reflected light in a specific direction and display a bright image. Since the direction is limited to a narrow range, there is a problem that only a very dark image can be obtained by slightly changing the viewing angle in the vertical direction. Further, there is a problem that the light from the left and right directions cannot be effectively used.

Further, as shown in FIG. 14B, when a reflecting plate having a large number of fan-shaped convex portions 101a formed on its surface is used, the light from the left and right directions is effectively utilized to some extent. However, the problem that only a very dark image can be obtained by slightly changing the viewing angle has not been solved because the collection direction of reflected light is limited to a narrow range. . Further, the large number of fan-shaped convex portions 101a are arranged at a predetermined interval, and the reflecting surface interposed between the adjacent convex portions 101a does not have a function of condensing the reflected light in a specific direction. Since it becomes a dead space, there is also a problem that the efficiency of collecting reflected light is low and a very bright image cannot be displayed.

Further, in the above-described conventional method for manufacturing a reflection plate, it is difficult to control the shape because an arbitrary inclination angle is obtained by applying a resist film and then inclining it to cause the film to flow. There is a problem that an optimum reflector shape cannot be obtained.

The present invention has been made to solve the above-mentioned problems of the conventional ones, and it is an object of the present invention to provide a reflective liquid crystal display device capable of obtaining a bright display image in a predetermined angle range. The first purpose. Also,
A second object is to provide a reflective liquid crystal display device that can effectively use light from the left and right directions. A third object is to provide a manufacturing method capable of easily manufacturing a reflector having a desired shape with good shape controllability. A fourth object is to provide a portable device that can obtain a bright image display with low power consumption.

[0015]

A reflective liquid crystal display device according to the present invention comprises a liquid crystal layer and a first liquid crystal layer for applying a voltage to the liquid crystal.
In a reflective liquid crystal display device including a second electrode and a reflection plate arranged on the back side when the liquid crystal layer is observed, the reflection plate has a rectangular shape inclined in a specific direction on its reflection surface. A large number of main inclined surfaces adjacent to each other in a direction intersecting the inclination direction are arranged at predetermined intervals so that the main inclined surfaces are displaced from each other in the inclination direction, and are adjacent to each other in a direction intersecting the inclination direction. An auxiliary inclined surface that connects the main inclined surfaces is arranged.

Further, in a reflective liquid crystal display device comprising a liquid crystal layer, first and second electrodes for applying a voltage to the liquid crystal, and a reflecting plate arranged on the back side when observing the liquid crystal layer, The reflection plate has a rectangular main inclined surface inclined in a specific direction on its reflection surface, and the main inclined surfaces adjacent to each other in a direction intersecting the inclination direction are arranged at predetermined intervals so that the main inclined surfaces are aligned in the inclination direction. A large number of them are arranged apart from each other, and a line segment having the same inclination as the main inclined surface is arranged between the main inclined surfaces adjacent to each other in the direction intersecting the inclination direction so that the main inclined surface is displaced in the inclination direction. An auxiliary inclined surface connecting the main inclined surface and the line segment is arranged.

Further, the average inclination angle of the rectangular main inclined surface inclined in a specific direction is in the range of 3 to 13 degrees.

Furthermore, the first and second electrodes are opposed to each other with the liquid crystal layer interposed therebetween, and the reflector also serves as the first electrode or the second electrode.

Further, the first and second electrodes are opposed to each other with the liquid crystal sandwiched therebetween, and a reflection plate is arranged on the opposite side of the first electrode or the second electrode from the liquid crystal layer with a planarizing layer interposed therebetween. is there.

Further, on the side which becomes the surface when observing the liquid crystal layer,
A front light having an outgoing light in an oblique direction corresponding to the inclination direction of the main inclined surface is arranged.

The method of manufacturing a reflective liquid crystal display device according to the present invention is the method of manufacturing a reflective liquid crystal display device according to any one of the above, wherein the step of forming a photosensitive material on the substrate and the main inclination are performed. Exposing the photosensitive material using a photomask in which a stripe pattern corresponding to the main inclined surface and a stripe pattern corresponding to the auxiliary inclined surface are combined to form a surface and an auxiliary inclined surface,
And a step of developing the photosensitive material exposed in the exposure step.

A portable device according to the present invention is equipped with the reflection type liquid crystal display device described in any one of the above.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 and 2
FIG. 1 is a diagram for explaining the shape of a reflection plate used in the reflection type liquid crystal display device according to the first embodiment of the present invention, and FIG. 1 (a) is a diagram in which a part of the reflection plate is observed obliquely from above.
(B) is a cross-sectional view taken along line BB of (a), (c) is C of (a).
-C line sectional view, (d) is a DD line sectional view of (a), FIG.
FIG. 2 is a sectional view taken along line EE of FIG. When incorporated in a reflective liquid crystal display device, that is, a liquid crystal panel and actually viewed, the left side of FIG. 1 is located above the liquid crystal panel and the right side is located below the liquid crystal panel. The lower side of FIG. 2 is located on the left side of the liquid crystal panel and the upper side is located on the right side of the liquid crystal panel.

1 and 2, 1a, 1b, 1
Reference numeral c (hereinafter, may be represented as 1 as a representative) is a rectangular main inclined surface inclined in a specific direction, and x is an arrow indicating the inclination direction. These main inclined surfaces 1a, 1
The main inclined surfaces (for example, the main inclined surfaces 1a and 1b) adjacent to each other in the direction intersecting the inclined directions (indicated by the arrow x) of b and 1c are displaced from each other in the inclined direction (for example, the main inclined surface 1a is A large number of them are arranged at a predetermined interval on the right side of the main inclined surface 1b).

As shown in FIG. 1 (b), the reflection plate BB
In a line cross section (a cross section obtained by cutting the reflection plate vertically through the main inclined surface 1a in the used state), its apex is unevenly distributed below the liquid crystal panel in the used state and both upper and lower side surfaces thereof are inclined. In use, the tilt angle of the tilted surface (main tilted surface 1a) on the upper side of the liquid crystal panel is smaller than the tilt angle of the tilted surface on the lower side of the liquid crystal panel, and the tilted surface on the upper side of the liquid crystal panel is the lower side of the liquid crystal panel. It inclines more gently than the inclined surface. That is, it has an asymmetrical zigzag shape.

Further, as shown in FIG. 1 (d), in the DD line cross section of the reflection plate (the cross section of the reflection plate cut vertically in the used state through the main inclined surface 1c), the use is similarly performed. In this state, the inclination angle of the inclined surface (main inclined surface 1c) on the upper side of the liquid crystal panel is smaller than the inclination angle of the inclined surface on the lower side of the liquid crystal panel, and the inclined surface on the upper side of the liquid crystal panel is the inclination of lower side of the liquid crystal panel. It is inclined more gently than the plane. That is, it has an asymmetrical zigzag shape. This is
The same applies to a cross section of the reflection plate cut vertically through the main inclined surface 1b in use.

Reference numerals 2b and 2c (hereinafter sometimes referred to as "2" as a representative) are auxiliary inclined surfaces for connecting the main inclined surfaces 1a and 1b and 1a and 1c which are adjacent to each other in a direction intersecting the inclination direction. As shown in FIG. 1C, also in the cross section taken along the line C-C of the reflection plate (a cross section of the reflection plate cut vertically through the auxiliary inclined surface 2c in the use state), similarly in the use state, the liquid crystal panel upper side. Inclined surface (auxiliary inclined surface 2
The inclination angle of c) is smaller than the inclination angle of the inclined surface on the lower side of the liquid crystal panel, and the inclined surface on the upper side of the liquid crystal panel is inclined more gently than the inclined surface on the lower side of the liquid crystal panel. That is, it has an asymmetrical zigzag shape. Note that this is the same in the cross section of the reflection plate that is cut vertically in the used state through the auxiliary inclined surface 2b.

Further, as shown in FIG. 2, the reflection plate EE
In a line cross section (a cross section of the reflection plate cut through in the use state through the main inclined surfaces 1a, 1b, 1c), the main inclined surfaces 1a, 1b, 1a adjacent to each other in the direction intersecting the inclination direction (lateral direction).
And 1c have different heights, and auxiliary inclined surfaces 2b and 2c connecting the main inclined surfaces 1a and 1b and 1a and 1c, respectively, are inclined. That is, the auxiliary inclined surfaces 2b and 2c
Is inclined in both a vertical section and a horizontal section in which the reflector is used.

Although not shown in the drawing, in the present embodiment, the inclined concavo-convex forming layer having the shape as shown in FIG. 1 is formed on the glass substrate, and the surface of the inclined concavo-convex forming layer is reflected. The reflective surface is formed by covering with a reflective layer made of a material. Therefore, the shape of the reflecting surface is as shown in FIG. The inclined concavo-convex forming layer is made of, for example, a photosensitive resin, and the reflective layer is made of a reflective material such as a metal containing aluminum as a main component and a trace amount of copper or silicon, or a metal containing silver as a main component and a trace amount of copper or palladium.

As an example, the length of the rectangular main inclined surface 1 in the inclination direction is 5 μm to 15 μm, and the length in the direction orthogonal to the inclination direction is 3 μm to 20 μm.

When light is incident on the reflection plate having such a shape from the upper left direction of FIG. 1B (the direction along the inclination direction x of the main inclined surface 1, that is, the upward direction in the used state), the main inclined surface is formed. Light is incident on and reflected on the auxiliary inclined surface 1 and the auxiliary inclined surface 2. At this time, the reflection direction of the light incident on the main inclined surface 1 is
The auxiliary inclined surface 2 has a specific direction corresponding to the inclination angle of
The reflection direction of the light incident on is slightly deviated from the specific direction according to the inclination direction of the auxiliary inclined surface 2. Therefore, the direction of the reflected light reflected by the reflection plate is not only the above-mentioned specific direction but also the direction spreading in the predetermined angular range around it as a whole.

Further, when light is incident on the reflection plate having such a shape from the upper left direction in FIG. 2 (direction orthogonal to the inclination direction x of the main inclined surface 1, that is, the left-right direction in use), the main inclined surface 1 And light is incident on the auxiliary inclined surface 2 and reflected.
At this time, the reflection direction of the light incident on the main inclined surface 1 is a direction symmetrical to the direction of the incident light. Therefore, light incident on the main inclined surface 1 at an angle close to vertical is reflected at an angle close to vertical as well and can be used for image display, but light incident at a shallow angle should be used. I can't. However, since the light incident on the auxiliary inclined surface 2c has a component that is closer to vertical than that of the case of the main inclined surface 1, it can be used for image display.

A specific target value of the inclination angle of the main inclined surface 1 will be described with reference to FIG. FIG. 3A is a diagram schematically showing a cross section of the reflection type liquid crystal display device according to the present embodiment, and FIG. 3B is an enlarged view of an X portion thereof. In FIG. 3, 50 is a back glass substrate, 51 is a reflection plate, and 5
Reference numeral 2 is a liquid crystal layer, 53 is a front glass substrate, 54 is a polarizing plate and a retardation plate, 60 is incident light, 61 is reflected light B, and 62 is reflected light A. The first and second electrodes for applying a voltage to the liquid crystal are arranged between the liquid crystal layer 52 and the front glass substrate 53 and between the liquid crystal layer 52 and the reflector 51, but they are omitted here. ing.

As shown in FIG. 3, when the direction R of the incident light 60 is 30 °, in order to direct the reflected light B61 to the direction of 0 ° which is the front surface of the reflective liquid crystal display device, the polarizing plate and the position are set. When the refractive index of the phase difference plate 54, the front glass substrate 53, and the liquid crystal layer 52 are approximated to be isotropic at 1.52 and calculated using Snell's law, the optimum value of the inclination angle γ of the main inclined surface 1 is calculated. Is 10 °.

It can be considered that the external light that actually enters the reflection type liquid crystal display device from outside has not only -30 degrees but also a distribution of about -10 degrees to -40 degrees. The optimum value of the inclination angle γ is 3 degrees to 13 degrees. Actually, it is difficult to manufacture a product having a completely uniform inclination angle, but if the average inclination angle is within the above range, a target can be obtained. By defining the average tilt angle in this way, light can be reflected in the most effective direction.

It should be noted that if the cross-sectional shape of the reflection plate cut vertically through the main inclined surface 1 shown in FIGS. 1B and 1D in a used state is symmetrical, the side opposite to the main inclined surface 1 Since the surface of 1 is an ineffective reflection surface and is not desirable, an asymmetrical shape in which the opposite side has a vertically raised triangular shape is desirable.

Note that FIG. 1 shows a part of the reflection plate, and shows the main inclined surface 1 in the inclination direction (vertical direction when the reflection plate is used: row direction) and the direction intersecting the inclination direction (reflection plate). Shows a state in which 3 rows and 3 columns are arranged in the left-right direction (column direction) in the use state. As an example of the overall arrangement of the main sloping surface 1, the main sloping surfaces 1 are arranged linearly in the inclination direction (row direction). In the direction (column direction) intersecting the tilt direction, for example, as shown in the plan view of a part of one column in FIG.
It may be shifted in two steps as shown in (b). Further, it may be shifted in three or more steps. It may also be offset in the tilt direction.

In the above description, the case where the reflection plate has a two-layer structure of a sloped concavo-convex forming layer made of, for example, a photosensitive resin and a reflection layer made of a reflective material such as metal formed thereon is described. Alternatively, the reflective material may be used alone.

The main inclined surface 1 and the auxiliary inclined surface 2 may be convex curved surfaces or concave curved surfaces instead of being flat surfaces.

Embodiment 2. 5 and 6 are views for explaining a method of manufacturing a reflective liquid crystal display device according to a second embodiment of the present invention. More specifically, FIG. 5 shows a general method of forming an inclined surface. 6 is a plan view showing a part of a photomask used for forming the main inclined surface and the auxiliary inclined surface in the present embodiment. Figure 5
In the figure, 15 is a photomask and 16 is light for exposure.

A general method of forming an inclined surface will be described with reference to FIG. First, as shown in FIG. 5A, a photosensitive resin as a photosensitive material is applied on the entire surface of the glass substrate 20 to form a photosensitive resin layer (gradient unevenness forming layer) 12.
At this time, a transistor or a wiring to be a driving circuit may be arranged in a part between the glass substrate 20 and the photosensitive resin layer 12. Next, as shown in FIG. 5B, the photosensitive resin layer 12 is exposed using a photomask 15, and
As shown in (c), it is partially removed by immersing it in a developing solution. When using a positive type photosensitive material, a photomask 1
The portion where the light 16 has passed through 5 is selectively scraped off by the developing solution. As an example of a specific material, as a photosensitive material, P which is a positive photosensitive material manufactured by JSR Corporation is used.
Using C335 (trade name) as a developing solution, TMAH (tetra-methyl-ammonium-hydroxide:
Tetramethyl ammonium hydr
oxide) 0.4 wt. It becomes possible if a% aqueous solution is used. At this time, the portion irradiated with the light 16 is moved to the glass substrate 20.
By carrying out the exposure and development processes under the condition that the film is not completely removed until it is exposed, the photomask 15 can be processed into a slightly deformed shape instead of the shape itself. Finally, as shown in FIG. 5D, the reflective layer 11 is formed on the photosensitive resin layer 12. By forming a shape having an arbitrary reflection characteristic by the method as described above, it becomes possible to manufacture the reflection plate with high mass productivity. Although the case where the positive photosensitive material is used has been described above, a negative photosensitive material may be used.

Next, the photomask used for forming the main inclined surface 1 and the auxiliary inclined surface 2 according to this embodiment will be described with reference to FIG. FIG. 6A is a plan view showing a part of a photomask in which a stripe pattern corresponding to the main inclined surface and a stripe pattern corresponding to the auxiliary inclined surface are combined, and FIGS. 6B to 6D show each stripe pattern. FIG. 5 is a diagram showing a distribution of the amount of light passing through the light (distribution of light on the photosensitive resin layer). FIG. 6B is a diagram showing the distribution on the line BB, FIG. 6C is a diagram showing the distribution on the line C-C, and FIG. 6D is a diagram showing the distribution on the line D-D. In FIG. 6, 15a and 15c are stripe patterns for forming the main inclined surface, and 15b is a stripe pattern for forming the auxiliary inclined surface. In FIG. 6, a black-painted portion is a light-shielding area (light-shielding area), specifically, a Cr film or the like is formed on a glass plate, and a non-filled portion is a light-transmitting area. (Translucent area), specifically, an area constituted only by a glass plate. In FIG. 6A, the stripe pattern is enlarged and shown for easy understanding.

The photomask shown here is formed by a zigzag combination of stripe patterns having slightly different line widths. Looking at one unit shown in FIG. 6A, the light-transmitting region is slightly larger on the left side, and the light-transmitting region is reduced toward the right side. As the stripe pattern width is made smaller, the light cannot completely pass through the photomask. Therefore, when the inclined surface is formed by exposure and development by the method described with reference to FIG. 5, the unevenness changes little by little. A gentle shape can be obtained.

Regarding the size of the stripe used here, for example, in an exposure apparatus using a wavelength of 436 nm, the numerical aperture NA (numerical) of the objective lens is
Aperture) is 0.15, the partial coherence factor of the illumination is 0.7, and the ratio of the pattern size on the photomask to the pattern size on the substrate is 1,
The width of each stripe is approximately 1.5 μm or less,
A desired shape can be obtained by forming by the method shown in FIG. If the size is larger than 1.5 μm, the inclined surface cannot be obtained. However, the mask (light-shielding area) line width is 0.3μ
Since it is difficult to manufacture a mask having a very small value such as m, the specific mask shape is, for example, a line width of 0.
What has been gradually changed between 8 μm and 1.2 μm may be combined.

Specifically, as shown in FIG. 6A, a photosensitive resin is used by using a photomask in which stripe patterns 15a and 15c corresponding to the main inclined surface and a stripe pattern 15b corresponding to the auxiliary inclined surface are combined. Expose the layers,
Then, by developing, a photosensitive resin layer (inclined concavo-convex forming layer) having a main inclined surface 1 and an auxiliary inclined surface 2 as shown in FIG. 1 is obtained, and a reflective layer is formed on the photosensitive resin layer. A reflective plate is obtained by forming.

Although FIG. 6 shows the case where the photosensitive resin 12 is a positive type, when the photosensitive resin 12 is a negative type, the photomask 1 shown in FIG.
In 5, the light-transmitting area and the light-shielding area are reversed.

Although the unit having the same mask pattern is repeatedly arranged in the example shown in FIG. 6, it may be a mask in which different units having different mask patterns with which the same characteristics are obtained are combined and arranged.

Embodiment 3. 7 and 8 are views for explaining the shape of the reflection plate used in the reflection type liquid crystal display device according to the third embodiment of the present invention, and FIG. 7 (a) shows a part of the reflection plate diagonally above. 7B is a sectional view taken along line BB of FIG. 7A, FIG. 8C is a sectional view taken along line CC of FIG. 7A, and FIG. 8 is a sectional view taken along line DD of FIG. 7A. Is. When incorporated in a reflective liquid crystal display device, that is, a liquid crystal panel and actually viewed, the left side of FIG. 7 is located above the liquid crystal panel and the right side is located below the liquid crystal panel. The lower side of FIG. 8 is located on the left side of the liquid crystal panel and the upper side is located on the right side of the liquid crystal panel.

In FIGS. 7 and 8, 3 is the main inclined surface 1.
Is a line segment having the same inclination as. 1 and 2 of the first embodiment, the present embodiment does not include the main inclined surface 1a, but instead, a line segment 3 having the same inclination as the main inclined surface 1a is placed at the same position as the main inclined surface 1a. The auxiliary inclined surfaces 2b and 2c connect the main inclined surface 1b and the line segment 3 and the main inclined surface 1c and the line segment 3 respectively. Since other configurations are the same as those in the first embodiment, the differences from the first embodiment will be mainly described below.

That is, the reflector according to the present embodiment is
The rectangular main inclined surfaces 1b and 1c inclined in a specific direction are
The main inclined surfaces 1b and 1c adjacent to each other in the direction intersecting with the inclination direction (indicated by the arrow x) are arranged at predetermined intervals so that the main inclined surfaces 1b and 1c are aligned with each other in the inclination direction. The main inclined surface 1b adjacent to each other in the direction intersecting
Line segment 3 having the same inclination as that of the main inclined surfaces 1b and 1c is arranged between the main inclined surfaces 1b and 1c such that the main inclined surfaces 1b and 1c are displaced in the inclination direction (shifted to the right in FIG. 7). Auxiliary inclined surface 2 that connects the main inclined surfaces 1b and 1c and the line segment 3, respectively
It is provided with b and 2c.

As shown in FIG. 7B, the reflection plate BB
In a line cross section (a cross section obtained by vertically cutting the reflector through the main inclined surface 1b in the used state), its apex is unevenly distributed below the liquid crystal panel in the used state and both upper and lower side surfaces thereof are inclined. In use, the tilt angle of the tilted surface (main tilted surface 1b) on the upper side of the liquid crystal panel is smaller than that of the tilted surface on the lower side of the liquid crystal panel, and the tilted surface on the upper side of the liquid crystal panel is the lower side of the liquid crystal panel. It inclines more gently than the inclined surface. That is, it has an asymmetrical zigzag shape. Note that this is the same in the cross section of the reflection plate that is cut vertically through the main inclined surface 1c in the used state.

In addition, as shown in FIG. 7 (c), also in the CC line cross section of the reflection plate (the cross section of the reflection plate which is cut vertically through the auxiliary inclined surface 2c in the used state), it is similarly used. The inclined surface (auxiliary inclined surface 2c) on the upper side of the liquid crystal panel in the state
Is smaller than the tilt angle of the tilted surface on the lower side of the liquid crystal panel, and the tilted surface on the upper side of the liquid crystal panel is tilted more gently than the tilted surface on the lower side of the liquid crystal panel. That is, it has an asymmetrical zigzag shape. Note that this is the same in the cross section of the reflection plate that is cut vertically in the used state through the auxiliary inclined surface 2b.

Also, as shown in FIG. 7D, in the DD line cross section of the reflection plate (the cross section of the reflection plate cut vertically in the usage state through the line segment 3), the usage state is also the same. , The inclination angle of the line segment 3 on the upper side of the liquid crystal panel is smaller than the inclination angle of the line segment on the lower side of the liquid crystal panel, and the line segment 3 on the upper side of the liquid crystal panel is gentler than that of the line segment on the lower side of the liquid crystal panel. It is inclined. That is, it has an asymmetrical zigzag shape.

Further, as shown in FIG.
In a line cross section (a cross section obtained by cutting the reflector horizontally through the main inclined surfaces 1b and 1c in use), the main inclined surfaces 1b and 1c adjacent to each other in the direction intersecting the inclination direction (lateral direction) have the same height. The line segment 3 disposed between the main inclined surfaces 1ab and 1c has a different height from the main inclined surfaces 1ab and 1c, and an auxiliary inclination connecting the main inclined surfaces 1b and 1c and the line segment 3 respectively. The surfaces 2b and 2c are inclined. That is, the auxiliary inclined surfaces 2b and 2c are inclined in both a vertical section and a horizontal section of the reflection plate in the use state.

Even the reflecting plate having such a shape has the same operation as that of the first embodiment, and the same effect can be obtained. That is, the reflection plate having such a shape is formed as shown in FIG.
When the light is incident from the upper left direction (the direction along the inclination direction x of the main inclined surface 1, that is, the upper direction in the use state), the light is incident on the main inclined surface 1 and the auxiliary inclined surface 2 and reflected. At this time, the reflection direction of the light incident on the main inclined surface 1 is a specific direction corresponding to the inclination angle of the main inclined surface 2, but the reflection direction of the light incident on the auxiliary inclined surface 2 is the same as that of the auxiliary inclined surface 2. It deviates a little from the above specific direction depending on the inclination direction. Therefore,
As a whole, the direction of the reflected light reflected by the reflector is not only the above-mentioned specific direction but also the direction that spreads around it in a predetermined angle range.

Further, when light is incident on the reflection plate having such a shape from the upper left direction in FIG. 8 (direction orthogonal to the inclination direction x of the main inclined surface 1, that is, the left-right direction in use), the main inclined surface 1 And light is incident on the auxiliary inclined surface 2 and reflected.
At this time, the reflection direction of the light incident on the main inclined surface 1 is a direction symmetrical to the direction of the incident light. Therefore, light incident on the main inclined surface 1 at an angle close to vertical is reflected at an angle close to vertical as well and can be used for image display, but light incident at a shallow angle should be used. I can't. However, since the light incident on the auxiliary inclined surface 2c has a component that is closer to vertical than that of the case of the main inclined surface 1, it can be used for image display.

Further, the reflection plate having such a shape has the stripe pattern 15 in FIG. 6A of the second embodiment.
It can be manufactured by a method similar to that of the second embodiment using a photomask shown in FIG. 9 in which c is omitted. Figure 9
FIG. 3 is a plan view showing a part of a photomask used for manufacturing the reflection type liquid crystal display device according to the present embodiment.

Fourth Embodiment FIG. 10 is a sectional view showing a reflective liquid crystal display device according to Embodiment 4 of the present invention.
This embodiment is characterized by a structure in which a voltage is directly applied to a reflection plate (reflection layer). In FIG. 10, 21 is a gate electrode, 22 is a gate insulating film, 23 is amorphous silicon, 24 is a source / drain electrode, 26 is a reflector,
30 is a back side glass substrate, 31 is a front side glass substrate, 32 is an alignment film, 33 is a black matrix, 34 is a transparent electrode, 35 is a color filter, 37 is a liquid crystal layer, 38 is a retardation plate, and 39 is a polarizing plate. In the present embodiment, the transparent electrode 34 corresponds to the first electrode that applies a voltage to the liquid crystal, and the reflection plate 26 (reflection layer 11) also serves as the second electrode. The first electrode (transparent electrode 34) and the second electrode (reflection layer 11) are arranged to face each other with the liquid crystal layer 37 in between.

The source / drain electrodes 24 of the TFT element and the reflection layer 11 of the reflection plate 26 are electrically connected to each other, and the alignment film 32, the liquid crystal layer 37, the alignment film 32, the transparent electrode 34, and the color layer are formed thereon. Filter 35, color filter side (front side) glass substrate 31, retardation plate 38, polarizing plate 39
It is configured as. When the guest-host type is used for the liquid crystal layer 37, the retardation plate 38 and the polarizing plate 39 are unnecessary.

When a voltage is applied to the liquid crystal, the reflective layer 26 and T
Since the source / drain electrodes 24 of the FT element are directly electrically connected, no voltage loss occurs and the liquid crystal can be driven at a low voltage.

Embodiment 5. 11 is a sectional view showing a reflective liquid crystal display device according to Embodiment 5 of the present invention.
In this embodiment, the transparent electrode 40 is arranged after the reflective layer 11 is flattened so that no voltage is directly applied to the reflective layer 11, and a voltage is applied to the liquid crystal between the transparent electrodes 34 and 40. It is characterized by a structure.

In FIG. 11, 36 is a flattening layer, and 40 is a transparent electrode corresponding to the second electrode. The first electrode (transparent electrode 34) and the second electrode (transparent electrode 40) are the liquid crystal layer 37.
The reflection plate 26 is arranged opposite to the liquid crystal layer 37 of the second electrode (transparent electrode 40) with the flattening layer 36 interposed therebetween. In the present embodiment, the arrangement is the same as that of the fifth embodiment described with reference to FIG. 10, except for the reflective layer 26, the flattening layer 36, and the transparent electrode 40.

Consider a problem that occurs when the surface of the reflection plate 26 (reflection layer 11) is not flattened. The thickness of the liquid crystal layer 37 is generally about 4 μm, and the reflective layer 1
If the height difference of 1 is 1 μm, the layer thickness of the liquid crystal has a distribution of center value plus or minus 0.5 μm. Since the optical characteristics of the liquid crystal are clearly different between the thin portion and the thick portion of the liquid crystal layer 37 even when the same voltage is applied, a distribution is generated in the brightness, which causes, for example, a decrease in contrast. In order to improve this, as shown in FIG. 11, the surface of the reflective film 26 is flattened by the flattening layer 36, and then the transparent electrode 40 for voltage application is applied.
Should be formed. As a result, it is possible to obtain the reflection plate 26 in which the optical adverse effect due to the unevenness of the reflection layer 11 is eliminated.

Sixth Embodiment FIG. 12 is a sectional view showing a reflective liquid crystal display device according to a seventh embodiment of the present invention.
In FIG. 12, 29 is a front light as an auxiliary light source. The front light 29 is disposed on the front side of the liquid crystal layer 37 and has an outgoing light in an oblique direction corresponding to the inclination direction of the specific inclined surface of the reflection plate 26.

For example, when the average inclination angle γ of the specific inclined surface of the reflection plate 26 is 3 degrees and the emission angle δ of the light from the front light 29 (shown by the arrow k ₁ ) is 10 degrees, the front light 29 is shown. The light (shown by the arrow k ₂ ) emitted from the light and reaching the specific inclined surface of the reflection plate 26 is reflected in the front direction of the reflective liquid crystal display device as shown by the arrow k ₃ . Therefore, it is possible to obtain a very bright image. At this time, a component (indicated by an arrow k ₄ ) unrelated to the display that is reflected on the surface of the reflective liquid crystal display device and a signal component (indicated by an arrow k ₃ ) that is reflected by the reflection plate 26 inside the reflective liquid crystal display device. It is possible to obtain an image in which the contrast of the signal component is high, because the directions do not overlap.

In each of the above-described first to sixth embodiments, the case where the first and second electrodes for applying a voltage to the liquid crystal are opposed to each other with the liquid crystal layer interposed is shown, but the present invention is not limited to this. , The first and second electrodes are both disposed on one side of the liquid crystal layer, and the liquid crystal is driven by an electric field having a component parallel to the glass substrate surface formed by the first electrode and the second electrode. Good. Such a liquid crystal display device is described in, for example, Japanese Patent Publication No. 63-21907, and is usually called an IPS (IN Plane Switching: lateral electric field application) type liquid crystal display device.

Embodiment 7. FIG. 13 is a diagram for explaining a mobile device according to a seventh embodiment of the present invention, and more specifically, is a diagram showing a state in which the above-described reflective liquid crystal display device is mounted on a mobile phone. . In FIG. 13, 4
1 is a mobile phone, 42 is a numeric keypad, 43 is a function key, 4
Reference numeral 4 is a liquid crystal display unit. The liquid crystal display section 44 has a large number of stripe-shaped convex portions having side surfaces inclined in a specific direction, which are described in any one of the first to sixth embodiments of the present invention, and arranged irregularly on the side surfaces. There is used a reflection type liquid crystal display device including a reflection surface having an island-shaped concave portion or an island-shaped convex portion formed therein, and a reflection plate made of a reflection material at least on the surface of the reflection surface.

The reflection type liquid crystal display device used here can obtain a bright image with low power consumption, and enables a long-time operation of a mobile phone driven by a built-in battery.

Further, not only the mobile phone shown in the above example but also other mobile devices such as a mobile information terminal and an electronic notebook, a bright display with low power consumption can be obtained.

[0070]

As described above, in the reflective liquid crystal display device according to the present invention, the liquid crystal layer and the first liquid crystal display device for applying a voltage to the liquid crystal are provided.
In a reflective liquid crystal display device including a second electrode and a reflection plate arranged on the back side when the liquid crystal layer is observed, the reflection plate has a rectangular shape inclined in a specific direction on its reflection surface. A large number of main inclined surfaces adjacent to each other in a direction intersecting the inclination direction are arranged at predetermined intervals so that the main inclined surfaces are displaced from each other in the inclination direction, and are adjacent to each other in a direction intersecting the inclination direction. Since the auxiliary inclined surface that connects the main inclined surfaces is arranged, it is possible to reflect light in a specific direction corresponding to the inclination direction of the main inclined surface and a predetermined angular range around it, and as a result, a predetermined angle is obtained. A very bright display image can be obtained in the range. Also,
Light from a direction orthogonal to the inclination direction of the main inclined surface can also be effectively used.

Further, in a reflective liquid crystal display device comprising a liquid crystal layer, first and second electrodes for applying a voltage to the liquid crystal, and a reflection plate arranged on the back side when observing the liquid crystal layer, The reflection plate has a rectangular main inclined surface inclined in a specific direction on its reflection surface, and the main inclined surfaces adjacent to each other in a direction intersecting the inclination direction are arranged at predetermined intervals so that the main inclined surfaces are aligned in the inclination direction. A large number of them are arranged apart from each other, and a line segment having the same inclination as the main inclined surface is arranged between the main inclined surfaces adjacent to each other in the direction intersecting the inclination direction so that the main inclined surface is displaced in the inclination direction. Since the auxiliary inclined surface connecting the main inclined surface and the line segment is arranged, it is possible to reflect light in a specific direction corresponding to the inclination direction of the main inclined surface and in a predetermined angular range around it. As a result, the non- Bright display image can be obtained. Further, the light from the direction orthogonal to the inclination direction of the main inclined surface can also be effectively used.

Furthermore, since the average inclination angle of the rectangular main inclined surface inclined in a specific direction is in the range of 3 to 13 degrees, it is possible to effectively utilize the external light and to make the vicinity of the front of the reflection type liquid crystal display device. In, a bright display image can be obtained.

Further, since the first and second electrodes are arranged so as to face each other with the liquid crystal layer interposed therebetween, and the reflecting plate also serves as the first electrode or the second electrode, the reflecting plate serves as the electrode as it is,
It is possible to drive the liquid crystal at a low voltage without causing a voltage loss.

Further, since the first and second electrodes are arranged to face each other with the liquid crystal sandwiched therebetween, and the reflection plate is arranged on the side opposite to the liquid crystal layer of the first electrode or the second electrode via the flattening layer, It is possible to obtain a reflection type liquid crystal display device in which the optical adverse effect due to the unevenness of the reflection surface of the reflection plate is eliminated.

Further, on the side which becomes the surface when the liquid crystal layer is observed,
Since the front light with the emitted light in the diagonal direction corresponding to the inclination direction of the main inclined surface is arranged, when the front light is turned on by optimizing the inclination angle of the side surface of the stripe-shaped convex portion and the emission angle of the front light. In addition, a bright and high-contrast display can be obtained in the front direction of the reflective liquid crystal display device.

Further, the method of manufacturing a reflective liquid crystal display device according to the present invention is the method of manufacturing a reflective liquid crystal display device described in any one of the above, in which a step of forming a photosensitive material on a substrate and a main inclination are performed. Exposing the photosensitive material using a photomask in which a stripe pattern corresponding to the main inclined surface and a stripe pattern corresponding to the auxiliary inclined surface are combined to form a surface and an auxiliary inclined surface,
Since the method includes the step of developing the photosensitive material exposed in the exposure step, the target reflector can be easily manufactured with good shape controllability. Moreover, the main inclined surface and the auxiliary inclined surface can be formed by one exposure step and one development step.

Further, since the portable device according to the present invention is equipped with the reflection type liquid crystal display device described in any one of the above,
Bright images can be obtained with low power consumption, and long-term operation is possible with a built-in battery.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the shape of a reflector used in a reflective liquid crystal display device according to Embodiment 1 of the present invention, FIG. 1 (a) is a diagram in which a part of the reflector is observed obliquely from above;
(B) is a cross-sectional view taken along line BB of (a), (c) is C of (a).
-C line sectional drawing, (d) is the DD sectional view taken on the line of (a).

FIG. 2 is a sectional view taken along the line EE of FIG.

FIG. 3 is a diagram illustrating the relationship between the tilt angle of a specific tilted surface of a reflection plate and reflected light according to the present invention.

FIG. 4 is a plan view showing an arrangement example in a direction intersecting with an inclination direction of a main inclined surface.

FIG. 5 is a diagram illustrating a method for manufacturing the reflective liquid crystal display device according to the second embodiment of the present invention.

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

FIG. 7 is a diagram for explaining the shape of a reflection plate used in the reflection-type liquid crystal display device according to the third embodiment of the present invention, (a) of FIG.
(B) is a cross-sectional view taken along line BB of (a), (c) is C of (a).
It is a -C line sectional view.

8 is a cross-sectional view taken along the line DD of FIG. 7 (a).

FIG. 9 is a plan view showing a part of a photomask used for manufacturing a reflective liquid crystal display device according to a third embodiment of the present invention.

FIG. 10 is a sectional view showing a reflective liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 11 is a sectional view showing a reflective liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 12 is a sectional view showing a reflective liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 13 is a diagram for explaining a mobile device according to a seventh embodiment of the present invention.

FIG. 14 is a diagram illustrating a reflector according to a conventional technique.

FIG. 15 is a diagram for explaining a method of manufacturing a reflection plate having an asymmetric reflection surface according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 main inclined surface, 2 auxiliary inclined surface, 3 line segments, 11 reflective layer, 12 photosensitive resin layer (inclined concavo-convex forming layer), 15 photomask, 15a, 15b, 15c stripe pattern, 20 glass substrate, 21 gate electrode, 22 gate insulating film, 23 amorphous silicon, 24 source / drain electrodes, 26 reflector, 29 front light, 30 back glass substrate, 31 front glass substrate, 3
2 alignment film, 33 black matrix, 34 transparent electrode (first electrode), 35 color filter, 36 flattening layer, 37 liquid crystal layer, 38 retardation plate, 39 polarizing plate, 40 transparent electrode (second electrode), 41 mobile phone Telephone,
42 numeric keys, 43 function keys, 44 LCD display,
50 back glass substrate, 51 reflector, 52 liquid crystal layer,
53 front glass substrate, 54 polarizing plate + retardation plate, 6
0 incident light, 61 reflected light B, 62 reflected light A, 101
Reflector, 101a convex portion, 102 substrate, 111 glass substrate, 112 resist film, 112a convex portion, 1
13 Photomask, 114 Metal thin film, 115 Reflector.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mitsuo Inoue             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Yasushi Orita             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F-term (reference) 2H042 DA02 DA04 DA07 DA11 DB08                       DC02 DC08 DE00                 2H091 FA16Y FA41X FD04 FD07                       FD23 GA02 GA16 LA03 LA12                       LA13 LA17

Claims (8)

[Claims] 1. A reflection type liquid crystal display device comprising a liquid crystal layer, first and second electrodes for applying a voltage to the liquid crystal, and a reflection plate arranged on the back side when observing the liquid crystal layer, The reflection plate has a rectangular main inclined surface inclined in a specific direction on its reflection surface, and the main inclined surfaces adjacent to each other in a direction intersecting the inclination direction are displaced at predetermined intervals so as to be displaced from each other in the inclination direction. The reflective liquid crystal display device is characterized in that a large number of auxiliary tilted surfaces are arranged to separate main tilted surfaces adjacent to each other in a direction intersecting the tilting direction. 2. A reflective liquid crystal display device comprising a liquid crystal layer, first and second electrodes for applying a voltage to the liquid crystal, and a reflection plate arranged on the back side when observing the liquid crystal layer, The reflection plate has a rectangular main inclined surface inclined in a specific direction on its reflection surface, and the main inclined surfaces adjacent to each other in a direction intersecting the inclination direction are arranged at predetermined intervals so that the main inclined surfaces are aligned in the inclination direction. A large number of them are arranged apart from each other, and a line segment having the same inclination as the main inclined surface is arranged between the main inclined surfaces adjacent to each other in the direction intersecting the inclination direction so that the main inclined surface is displaced in the inclination direction. A reflection type liquid crystal display device, characterized in that an auxiliary inclined surface for connecting the main inclined surface and a line segment is arranged. 3. The reflection type liquid crystal display device according to claim 1, wherein an average tilt angle of the rectangular main tilt surface tilted in a specific direction is in the range of 3 degrees to 13 degrees. 4. The reflective liquid crystal according to claim 1, wherein the first and second electrodes are arranged to face each other with a liquid crystal layer interposed therebetween, and the reflector also serves as the first electrode or the second electrode. Display device. 5. The first and second electrodes are arranged to face each other with a liquid crystal sandwiched therebetween, and a reflector is arranged on the opposite side of the first electrode or the second electrode from the liquid crystal layer with a flattening layer interposed therebetween. The reflective liquid crystal display device according to claim 1 or 2. 6. A front light having an emission light in an oblique direction corresponding to the inclination direction of the main inclined surface is arranged on the front side when observing the liquid crystal layer.
The reflective liquid crystal display device described. 7. The method of manufacturing a reflective liquid crystal display device according to claim 1 or 2, wherein a step of forming a photosensitive material on a substrate, and a main inclined surface and an auxiliary inclined surface are formed. Exposing the photosensitive material using a photomask in which a stripe pattern corresponding to the main inclined surface and a stripe pattern corresponding to the auxiliary inclined surface are combined; and developing the photosensitive material exposed in the exposing step. The manufacturing method of the reflection type liquid crystal display device, comprising: 8. A portable device comprising the reflection type liquid crystal display device according to claim 1.