JPH0153477B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light-receiving type electro-optical element that is easy to see even when light is incident from an oblique direction.

Light-receiving electro-optical elements have been used in many applications such as watches, calculators, and game consoles. A typical example of this is a liquid crystal element, which is normally used under both electric light and sunlight, using light that comes from directly above or slightly obliquely to the liquid crystal element, and the display is viewed using the reflected light. It was hot. For this reason,
A reflector was used on the back side of the liquid crystal element, but as mentioned above, this reflector improves the reflection characteristics from directly above, so it has high reflection characteristics in the direction directly above, for example, as shown in Figure 1. Reflection characteristics (horizontal axis inclination angle, vertical axis reflected light ratio (arbitrary units)) were used. When using a reflector with such characteristics, it has the advantage of being easy to see due to its good reflection performance when it receives light from directly above or at an angle of about ±20°, but on the other hand, it has the advantage of being easy to see when receiving light from directly above or at an angle of about ±20°. It was extremely difficult to see under the bright light.

In recent years, consideration has begun to be given to the use of such electro-optical elements in automobiles, but since light enters automobiles only from very oblique directions unless they are used in a fully transmissive type, it is difficult to actually use conventional reflectors. If it were installed, it would be extremely difficult to see.

The present invention aims to improve such drawbacks and provide an electro-optical element for use in automobiles that is easy to see even when light is incident from an oblique direction.
In an electro-optical device that consists of a cell made up of substrates with electrodes facing each other and a reflector, the depth is
This is an electro-optical element characterized in that it uses a reflecting plate formed by forming substantially spherical curved concave or convex portions with a pitch of 50 to 500 μm, with a diameter of more than 5 μm and less than 30 μm.

The electro-optical element of the present invention has good reflection characteristics even for light incident from an oblique direction, and there is almost no change in the amount of reflected light up to about ±50 degrees, and when used for applications such as automobiles, it A high-quality display can be obtained even when light is incident from an angle.

A typical example of the electro-optical device of the present invention is a liquid crystal device (LCD), and it can also be applied to an electrochromic display device (ECD), but in the following explanation, the LCD will be described as a typical example.

To explain this LCD in more detail,
A polarizing film, a color polarizing film, a color filter, a mask printing, an antireflection layer, etc. may be provided on the substrate surface, and an undercoat layer such as SiO ₂ or an oriented overcoat layer such as polyimide or SiO ₂ may be provided on the inner surface of the substrate. , a vertical alignment treatment agent layer such as silane, etc. may be provided, and configurations such as multilayer electrodes, multilayer cells, film electrodes, etc. may be used together, and nematic liquid crystal,
Cholesteric liquid crystals, as well as pleochroic dyes, optically active substances, fluorescent substances, etc. can be added as necessary and used, as long as the reflective plate of the present invention can be placed on the back side. Can be used.

FIG. 2 is a cross-sectional explanatory diagram of a typical example.
For the sake of clarity, the thickness in the cross-sectional direction is shown partially thickened, and the electrodes and liquid crystal layer are actually extremely thin.

A front substrate 2 having an electrode 1 and a rear substrate 4 having an electrode 3 are placed facing each other, the periphery thereof is sealed with a sealant 5, a liquid crystal 6 is injected inside, and a sealant (not shown) is sealed on both sides. Polarizing plates 7 and 8 are arranged, and a reflecting plate 9 of the present invention is further arranged on the back side. This example only shows a very basic structure, and various applications as mentioned above are possible.
It is also possible to use EPID, LED, fluorescent display tube, etc. in combination.

Further, the reflector plate 9 may be adhered to the back surface of the element, may simply be in close contact with it, or may be placed a little apart.

The reflector of the present invention is not limited to a perfect reflector, but may also be a semi-transmissive reflector, and is formed by forming concave or convex portions of a substantially spherical curved surface with a depth of at least more than 5μ and 30μ or less with a pitch of 50 to 500μ. This makes it possible to better reflect light from oblique directions than conventional reflectors with irregularities. Particularly preferred is a depth of 10 to 25 μm and a pitch of 100 to 400 μm for easy visibility.

Figure 3 shows a cross-sectional view of a reflector plate with concave portions, and Figure 4 shows a cross-sectional view of a reflector plate with convex portions. 1 is assumed to be 50 to 500μ. The concave or convex portions of this approximately spherical curved surface may be any substantially uniform curved surface such as a spherical surface or a paraboloid, and the reflection angle θ of incident light from the vertical direction may be used.
It is sufficient if the angle is set to about 30 to 65 degrees on average.

When viewed in a plan view, the concave portions or convex portions are arranged alternately like a face-centered cubic structure in a crystal structure, so that incident light from many directions can be accommodated. Also, by arranging them in a specific direction, for example,
By arranging them vertically and horizontally and changing the pitch in the vertical and horizontal directions, it is possible to increase the reflectance for incident light from a specific direction.

Further, although a portion without a concave portion or a convex portion may be provided as appropriate, as the number of flat portions increases, the reflectance for incident light from directly above increases.

Furthermore, when the pitch is increased, it is also preferable to increase the depth.

The electro-optical element of the present invention is easy to see when light is incident from an oblique direction, such as in an automobile, and by applying color polarizing plates, color filters, guest-host elements, etc., beautiful color display can be achieved. By using a transmissive and semi-reflective plate, it is possible to use a transmissive type and a reflective type in combination, and various applications are possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the reflected light ratio of a conventional reflector.
FIG. 2 is a sectional view of the liquid crystal element of the present invention. FIG. 3 and FIG. 4 are cross-sectional explanatory views of the reflector of the present invention. 1, 3: electrode, 2, 4: substrate, 9: reflection plate.

Claims (1)

[Scope of Claims] 1. An electro-optical element in which substrates with electrodes are opposed to each other to form a cell, and a reflective plate is disposed,
An electro-optical element characterized in that it uses a reflecting plate formed by forming substantially spherical curved concave or convex portions with a depth of more than 5μ and 30μ or less with a pitch of 50 to 500μ. 2 The depth of the concave or convex portion of the reflector is 10 to 25μ,
The electro-optical element according to claim 1, wherein the electro-optical element has a pitch of 100 to 400μ. 3. The electro-optical element according to claim 1 or 2, wherein the concave portion or convex portion of the reflector plate has an average reflection angle of 30 to 65 degrees for vertically incident light.