JPH11142627A - Prism type translucent reflecting plate and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device capable of forming a reflection and transmission both use type liquid crystal display device which shows brightness being equal to that of a conventional reflection type exclusive reflecting plate in a reflection mode and shows sufficient brightness and is superior in visibility even in a transmission mode by obtaining a translucent reflecting plate with a large degree of freedom for balancing reflectivity and transmissivity. SOLUTION: A metal vapor-deposited layer 12 is installed on the prismatic uneven surface of a transparent base material 11 having a structure where the prismatic unevenness is repeated, a prism type translucent reflecting plate which has a reflecting surface 13 and a transmission surface 14 for light is arranged based on the projection parts of the prismatic unevenness and a surface light source which shows directivity to the light transmission surface of the prismatic uneven surface is arranged on the opposite surface to the prismatic unevenness formation surface of the reflecting plate. Consequently, the areas of the light reflecting surface and light transmitting surface can individually be set with a large variation width by sharing reflection and transmission through the formation surface of the prismatic uneven structure and the reflectivity and transmissivity can be balanced individually with a large degree of freedom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prism type semi-transmissive reflector and an illuminating device suitable for forming a reflection type or a reflection / transmission type liquid crystal display device.

[0002]

BACKGROUND OF THE INVENTION Conventionally, as a transflective plate which can be used for forming a reflective / transmissive liquid crystal display device, a resin sheet containing scale-like reflective particles such as mica, or a metal vapor-deposited layer on a resin sheet is used. It has been known that the thickness is controlled so as to exhibit reflectivity and transmissivity. However, since the balance between reflectivity and transmissivity is determined uniquely by the blending amount of the flaky reflective particles and the thickness of the metal deposition layer, the relationship between reflectivity and transmissivity is opposite, so that reflectivity and transmissivity are There is a problem that the degree of freedom for balancing is small.

[0003]

SUMMARY OF THE INVENTION The present invention provides a semi-transmissive reflector having a high degree of freedom to balance the reflectivity and the transmissivity, and in a reflection mode, exhibits a brightness comparable to that of a conventional reflector dedicated to a reflection type. It is an object of the present invention to provide an illumination device which can form a reflection-transmission type liquid crystal display device exhibiting sufficient brightness even in a transmission mode and having excellent visibility.

[0004]

According to the present invention, there is provided a transparent base material having a repeating structure of prismatic irregularities, wherein a metal deposition layer is provided on the prismatic irregularities, and light is transmitted based on the convexities of the prismatic irregularities. A prism type semi-transmissive reflector characterized by having a reflective surface and a transmissive surface, and a directivity to the light transmitting surface of the prismatic irregular surface on a side of the reflector opposite to the prism-shaped irregular surface. The present invention provides a lighting device characterized by arranging a surface light source indicating the following.

[0005]

According to the present invention, the reflection / transmission can be shared through the formation surface of the prismatic uneven structure, and the areas of the light reflection surface and the light transmission surface can be independently set with a large variation width, and the reflection and transmission characteristics can be improved. The transparency can be uniquely balanced with great freedom,
It is possible to obtain reflected light and transmitted light that are excellent in light quantity.

[0006] As a result, a reflection area comparable to that of the conventional reflection-type dedicated reflection plate can be easily secured, and in the reflection mode, the brightness is comparable to that of the conventional reflection-type dedicated reflection plate, and the light transmission surface is also large. The lighting system combined with a surface light source that shows sufficient brightness even in the transmission mode and shows directivity with respect to the light-transmitting surface is bright and has excellent visibility.
A transmissive liquid crystal display device can be formed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The prism type semi-transmissive reflection plate of the present invention comprises a transparent base material having a repeating structure of prismatic irregularities, wherein a metal deposition layer is provided on the prismatic irregularities, and the prismatic irregularities are provided. It has a light reflection surface and a light transmission surface based on the convex portion. Examples are shown in FIGS. 1 is a prism type transflective plate, 11 is a transparent substrate,
12 is a metal deposition layer, 13 is a light reflection surface, and 14 is a light transmission surface. Further, 2 and 21 are buried layers, and 22 is light scattering particles.

The illumination device according to the present invention is further characterized in that the surface of the prism type semi-transmissive reflection plate has directivity with respect to the light transmitting surface of the prismatic irregular surface on the side opposite to the prismatic irregularity forming surface. Are arranged. An example is shown in FIG. 3 is a surface light source, 31 is a light guide plate, 32 is a light source, 3
3 is a reflective layer. FIG. 3 shows a liquid crystal display device for both reflection and transmission, and 4 is a liquid crystal cell.

The transparent substrate can be formed of an appropriate transparent substance such as glass or polymer, and the material for forming the transparent substrate is not particularly limited. Generally, it is formed of a polymer exhibiting good transparency to incident wavelength light, particularly visible light. Examples of such polymers include polyolefins and various synthetic rubbers,
Polycarbonate and polystyrene, polyimide and polyamide, cellulosic polymer and polyvinyl alcohol,
Polyacrylates and polymethacrylates,
Examples include polyurethane, polyurethane acrylate, polyvinyl chloride and polyester, epoxy resin and epoxy acrylate.

The prismatic irregularities on the transparent base material are provided as a repetitive structure of a large number of irregularities. The form of the prismatic irregularities is not particularly limited. Appropriate forms such as a form consisting of a curved surface or a circular surface, a form consisting of a triangular prism, a triangular pyramid or a dome, a step form or a multi-step form having a step portion can be adopted. Further, the prism-shaped irregularities may be formed as a continuous surface or as a discontinuous surface.

Further, the repeating structure of the prism-shaped unevenness may be formed by the same shape of the unevenness, or may be formed by the different shape of the unevenness. Further, the repeating structure may be one in which prismatic irregularities are regularly arranged,
They may be arranged irregularly. A repetitive structure in which prism-shaped irregularities having substantially the same form are regularly arranged is preferable to unifying the emission direction over the entire surface.

The above-mentioned regular arrangement state may be, for example, a column, a row, a diagonal row, a diagonal row, a diagonal row, a diagonal row, a diagonal row, a diagonal row, a diagonal row, or a diagonal row. An array composed of a combination with a column is exemplified. Therefore, a stripe-like arrangement, a polygonal arrangement such as a triangular or lattice-like arrangement and the like are also included. Therefore, the prismatic irregularities may be one-dimensionally arranged in one direction, or two-dimensionally arranged in a predetermined arrangement state in which concave portions are formed in multiple directions such as vertical and horizontal, and discontinuous convex portions are formed. They may be arranged.

By controlling the form such as the inclination angle of the above-mentioned prismatic irregularities and its repetitive structure, the angle of emission of reflected light through the light reflecting surface and the angle of emission of transmitted light through the light transmitting surface are controlled. Can be adjusted. Therefore, the inclination angle of the light reflecting surface is appropriately determined according to the emission direction of the target reflected light, the light use efficiency, the cut angle of the obliquely incident light, and the like. Generally, the inclined surface is 45 degrees or less, preferably 1 to 30 degrees, particularly 5 to 20 degrees with respect to the horizontal plane of the transparent substrate.

Incidentally, in FIG. 1, the inclination angles θ ₁ , θ ₂ , and θ ₃ of the light reflecting surface 13 are set to 30 degrees, 20 degrees, and 10 degrees, and the inclination angles θ ₁ , θ ₂ , and θ ₃ are combined. By using a repetitive structure, it is possible to obtain a reflector plate having reflected light peaks at three different emission angles as shown in FIG. By diffusing the reflected light through a light scattering layer or the like, a trapezoidal emission characteristic as shown in FIG. 5 can be obtained, and the trapezoidal emission characteristic has a small difference in brightness when the viewing angle is changed,
It has the advantage that good visibility can be achieved with a wide viewing angle. The emission characteristic in which the emission direction of the reflected light is constant can be achieved by making the inclination angle of the light reflection surface constant.

On the other hand, as shown in FIG. 1, the inclination angle θ ₄ of the light transmitting surface 14 is also appropriately determined according to the emission direction of the transmitted light, the light use efficiency, the cut angle of the obliquely incident light, and the like. You. In addition, the inclination angle of the light reflection surface and the light transmission surface cannot be set completely independently because of the prism-shaped unevenness. Even if the reflection surface and the light transmission surface have a wide degree of freedom in adjusting the height of the unevenness, etc. Tilt angles affect each other.

In the present invention, taking into consideration that the intensity of transmitted light can be controlled by the luminance of a surface light source, etc., the balance between the reflected light characteristics in the reflection mode and the transmitted light characteristics in the transmission mode is considered. Thus, the inclination angle of the light transmitting surface is 45 degrees or more, particularly 70 degrees or more, based on the horizontal plane of the transparent substrate,
In particular, it is preferable that the angle be 80 degrees or more. In addition, it is also acceptable that the light transmission surface has a prismatic unevenness with an inclination angle of 90 degrees or more.

The width (pitch) of the prismatic irregularities can be appropriately determined according to the purpose of use and the like, and is generally 5 mm or less, preferably 1 μm to 1 mm or less, particularly 5 to 500 μm. When used in a liquid crystal display device, a structure in which a repetitive structure of prismatic irregularities is formed at a pitch smaller than the pixel pitch of the liquid crystal cell, particularly 以下 or less, particularly １ ／ or less,
It is particularly preferable in terms of prevention of moiré and expansion of a viewing angle. In order to improve the vertical and horizontal viewing angle characteristics in a reflection mode in a liquid crystal display device or the like, it is advantageous to form a triangular or trapezoidal uneven pattern in a regular pattern with a constant pitch such as a stripe or grid.

The production of a transparent substrate having a repeating structure of prismatic irregularities is carried out, for example, by preparing a liquid substrate which can be polymerized by heat, radiation or the like onto a mold on which a predetermined shape (repeating structure of prismatic irregularities) is transferred and formed. A method of casting a material forming material and performing a polymerization treatment, a method of pressing a thermoplastic resin onto a mold or the like in which a predetermined shape is formed, and transferring a surface shape of the mold or the like, or a method in which the predetermined mold or the like is used. A method of filling and molding a thermoplastic resin,
A method in which a polymer, such as a solvent solution or a melt, is extruded from a nozzle having a molding opening of a predetermined shape onto a table and solidified,
It can be formed by an appropriate method such as a method of attaching a repeating structure of prism-shaped irregularities separately formed on a base material, or a mask exposure method of irradiating a polymer layer with ultraviolet rays or the like through a mask.

The repeating structure of prismatic irregularities can also be formed by a method of attaching prismatic irregularities made of the same or different material to a transparent base material. From the viewpoint of improving the light use efficiency by preventing reflection loss and the like, it is preferable that the entire transparent substrate including the repeating structure of prismatic irregularities is integrally formed of the same material.

The thickness of the transparent substrate provided with the prismatic irregularities can be appropriately determined according to the purpose of use, etc., but is generally preferably as thin as possible, usually 3 mm or less, especially 10 μm to 1 m.
m, especially 30 to 500 μm. The height or depth of the prismatic irregularities can also be appropriately determined according to the purpose of use and the balance of the amount of reflected light and transmitted light, and is generally 3 mm or less, particularly 0.1 μm to 1 mm, particularly 1 to 500 μm. .

The transflective plate can be formed by providing a metal vapor deposition layer on the light reflecting surface of the prismatic irregular surface of the transparent substrate. That is, usually, when the vapor deposition process is performed under the condition that the vapor deposition layer having the thickness d is formed on the surface parallel to the vapor deposition source, the thickness becomes d on the surface having the inclination angle θ.
A cos θ deposited layer is formed.

Therefore, the vapor deposition source and the surface serving as the light reflecting surface of the prismatic irregularities are disposed so as to be as parallel as possible, and the vapor deposition treatment is performed so that the vapor deposition on the surface serving as the light transmitting surface of the prismatic irregularities is achieved. Can be suppressed, and an evaporation treatment showing light reflectivity and light transmittance can be performed. When the transparent base material is arranged so that the surface serving as the light reflecting surface of the prismatic irregularities is parallel to the vapor deposition source, and the angle of the surface serving as the light transmitting surface of the prismatic irregularities with respect to the vapor deposition source is 90 degrees or more. The above d
From the relationship of cos θ, it is theoretically possible to prevent the deposition layer from being formed on the surface that becomes the light transmitting surface, and a surface excellent in light transmittance is formed in practice.

The vapor deposition may be performed by a suitable method such as a vacuum vapor deposition method or a sputtering method, and an appropriate metal such as aluminum or silver may be used as a metal for vapor deposition. In addition, the metal deposition layer on the light reflecting surface can be formed as a single layer or as a superimposed layer of two or more layers, and if necessary, provides reflected light having polarization characteristics such as linearly polarized light having a multilayered structure of the metal deposition layers. It can also be done.

The thickness of the metal deposited layer on the light reflecting surface is preferably 80 nm or more, more preferably 100 nm or more, from the viewpoint of light reflectivity and the like.
In particular, the thickness is preferably 200 nm or more. On the other hand, the thickness of the metal vapor-deposited layer on the light transmitting surface is preferably 800 nm or less, more preferably 400 nm or less, and particularly preferably 200 nm or less from the viewpoint of light transmittance and the like.

On the prism-shaped uneven surface provided with the metal deposition layer, a burying layer for filling at least the concave portion of the prism-shaped unevenness can be provided as required, as shown in FIGS. The buried layer can be formed as a layer having an appropriate purpose, such as a resin layer for controlling the emission direction through refraction or the like, or an adhesive layer for bonding to a liquid crystal cell or the like.

For the formation of the resin layer, an appropriate light-transmitting substance such as the polymer exemplified for the transparent substrate can be used, and the type thereof is not particularly limited. Also in the formation of the adhesive layer, for example, a transparent adhesive made of an appropriate polymer such as an acrylic polymer or a silicone polymer, polyester or polyurethane, polyether or synthetic rubber can be used. There is no limitation. Buried with a material with a refractive index larger than the refractive index of the material that forms the prismatic irregularities, such as to prevent a reduction in the amount of emitted light due to total reflection based on the difference between the refractive index of the prismatic irregularities of the transparent resin and the embedded layer Preferably, a layer is formed.

The buried layer may be formed by an appropriate method such as a fitting arrangement of a buried base material having an uneven shape corresponding to the prismatic unevenness of the transparent base material, or a method of applying and solidifying a fluid such as a burying layer forming material solution. It can be formed in a manner. The thickness of the buried layer is
The thickness can be appropriately determined by controlling the emission direction by refraction, the adhesive force, and the like, and can be made to have a thickness exceeding the convex portion of the prismatic irregularities of the transparent substrate as shown in the figure.

When the reflected light via the light reflecting surface of the prismatic irregularities shows a strong peak as described above, a display having a large difference in brightness due to a change in the viewing angle is displayed as it is. Preferably scatters the reflected light. The light scattering is performed by, for example, roughening the prism-shaped uneven surface by an appropriate method such as matting to give a fine uneven structure to the metal deposition layer, and / or providing a light scattering layer on the prism-shaped uneven surface. It can be performed by an appropriate method such as.

The light scattering layer can be used as the above-mentioned buried layer, or can be provided as a separate layer from the buried layer. Incidentally, the light scattering layer which is also used as the buried layer is made of, for example, a phase separation method of the buried layer, transparent fine particles made of an appropriate inorganic substance such as silica particles or calcium oxide particles having different refractive indexes in the buried layer, and / or polymethyl methacrylate or polyureta. Formed by an appropriate method such as a method of including crosslinked or uncrosslinked transparent fine particles made of an appropriate polymer such as a method of imparting a fine uneven structure to the surface of the burying layer by an appropriate method such as embossing roll, sandblasting or etching. can do.

On the other hand, the light-scattering layer separate from the buried layer may be formed by a method of providing a layer according to the light-scattering layer also serving as the buried layer on the buried layer or a method of providing an adhesive layer containing transparent fine particles. It can be formed by any method. The light scattering layer is
Two or more layers may be provided as the buried layer or the separate arrangement layer.

The transparent fine particles contained in the light scattering layer have an average particle diameter of 50 μm in view of light transmittance and scattering properties, and when used in a liquid crystal display device, in consideration of prevention of moire and the like. Hereinafter, those having a particle size of 20 μm or less, particularly 10 μm or less can be preferably used. Measures for light scattering
The present invention can also be applied to a method in which a light scattering layer such as an antiglare layer is provided on a display device such as a liquid crystal cell.

In the case where the above-mentioned reflected light shows a polarization characteristic, it is difficult to cancel the polarization state, especially, the polarization state is 95% or more, particularly 99% or more, and further 99.5.
% Is preferable. A reflector exhibiting such a polarization maintaining property can be obtained, for example, as a reflective layer having excellent specular reflectivity or a layer having a small phase difference due to birefringence, particularly having a buried layer having a phase difference of 100 nm or less, particularly 50 nm or less. Can be.

The transflective plate of the present invention can provide the reflected light via the light reflecting surface and the transmitted light via the light transmitting surface, and is used for a reflection type or a reflection / transmission type liquid crystal display device. It can be preferably used for formation. A reflective or transflective liquid crystal display device can be obtained by arranging a liquid crystal cell 4 on a transflective reflector 1 as illustrated in FIG.
In the case of a transmissive type liquid crystal display device, it is arranged as a lighting device provided with a surface light source 3 on the side of the semi-transmissive reflection plate 1 opposite to the surface on which the prismatic irregularities are formed.

As the above-mentioned surface light source, an appropriate one known in a transmissive liquid crystal display device such as a side light type light guide plate or an EL lamp can be used. By the way, the light guide plate has a reflective layer on the back surface as necessary and emits light to the front side, and guides a linear light source such as a (cold, hot) cathode tube or a light source such as a light emitting diode. A side light type backlight known in liquid crystal display devices, which is disposed on the side surface of the light plate 31 and emits light transmitted through the light guide plate to one side of the plate by diffusion, reflection, diffraction, interference, or the like. Is an example.

The light guide plate which emits the internal transmission light to one side includes, for example, a transparent or translucent resin plate having a light emitting surface or a diffuser provided in a dot or stripe shape on the back surface thereof, It can be obtained as a resin plate having a concave and convex structure, particularly, a fine prism array-shaped concave and convex structure on the back surface.

The surface light source 3 illustrated in FIG. 3 includes a light source 32 disposed on a side surface of a light guide plate 31 and a reflection layer 33 provided on a back surface. The light is incident, exits from the surface of the light guide plate via reflection on the back surface, etc., and enters the transflective plate 1. The reflection layer 33 on the back surface of the light guide plate is intended to prevent light leakage from the back surface.

In the present invention, a surface light source which can be used more preferably, for example, to obtain bright transmitted light by efficient light emission, exhibits directivity to the light transmitting surface 14 of the prism-shaped uneven surface of the transflective reflector 1. Things. A surface light source exhibiting such directivity can be obtained, for example, as a sidelight-type backlight using a light guide plate having an uneven structure on the back surface, particularly, a fine prism array-shaped uneven structure.
According to the concave / convex structure in the form of a fine prism array, good directivity with respect to the light transmitting surface by controlling the inclination angle and arrangement state of the prism surface, such as the prismatic concave / convex surface of the transflective plate according to the present invention. Can be easily obtained.

When forming the illumination device, a prism array layer composed of a prism sheet or the like for controlling the light emission direction, a diffusion plate for obtaining uniform light emission, a reflection means for returning leaked light, a linear light source Auxiliary means such as a light source holder for guiding the light emitted from the light guide plate to the side surface of the light guide plate may be appropriately combined with one or more layers by arranging one or more layers at predetermined positions such as upper and lower surfaces and side surfaces of the light guide plate. You can also.

Each component such as a semi-transmissive reflector, a surface light source, and a light guide plate associated therewith, which form the lighting device, can be laminated and integrated via an adhesive layer as necessary. The lamination and integration of the formed components is effective for suppressing reflection loss at each interface, preventing deterioration of display quality or the like by preventing foreign matter or the like from entering each interface, and preventing displacement of an optical system. An appropriate adhesive such as an adhesive can be used for the lamination and integration.

As described above, the illuminating device of the present invention combines the light from the surface light source with the light having the prismatic irregularities in the semi-transmissive reflection plate by combining the transflective plate with an appropriate surface light source such as a sidelight type light guide plate. The light is emitted from the transmission surface. In that case,
Since the direction of light emitted from the light transmission surface is not usually perpendicular to the semi-transmissive reflection plate, one or more light scattering layers are provided between the transparent substrate and a display device such as a liquid crystal cell. It is more preferable to emit the transmitted light from the light transmitting surface in a direction perpendicular to the transflective plate as shown by the arrow in FIG. 3 from the viewpoint of improving the visibility of the display device in the transmission mode.

It should be noted that the prism type semi-transmissive reflection plate and the illuminating device of the present invention may be provided with an adhesive layer for the purpose of bonding to the adherend as described above. The attachment of the adhesive layer can be performed by an appropriate method such as a method of applying an adhesive using an appropriate coating machine or a method of transferring an adhesive layer provided on a separator. The thickness of the adhesive layer can be determined according to the purpose of use. Until the attached adhesive layer is put to practical use,
It is preferable to temporarily attach and protect a separator or the like.

Further, the surface of the prism type semi-transmissive reflection plate or the lighting device may be subjected to anti-glare treatment or anti-reflection treatment for preventing visual disturbance due to reflected light, if necessary. The anti-glare treatment and the anti-reflection treatment can be performed according to the conventional method. Incidentally, the anti-reflection layer is made of, for example, magnesium fluoride or a fluorine-based resin having a refractive index of 1.38 or less, and has a thickness of 50 to 300 nm. As a low refractive index transparent film or a multilayer thin film.

The prism type semi-transmissive reflector and the lighting device of the present invention control the emission direction of reflected light or transmitted light by the shape and size of the prismatic irregularities, the arrangement and pitch, and the refractive index difference from the buried layer. By using a prism type semi-transmissive reflector that is suitable for the purpose of improving the visibility characteristics, it is possible to improve the visibility characteristics such as adjusting and enlarging the viewing angle in the reflection mode and the transmission mode, and improving the brightness. . It should be noted that the prism type semi-transmissive reflection plate, based on the outer surface on which the buried layer and the like are provided, is in a planar state except for fine irregularities due to the light diffusion layer, and in particular, it is in a parallel plane state on the front and back sides of reflected light and transmitted light It is more preferable to make the emission direction constant.

Therefore, the prism type semi-transmissive reflector and the lighting device of the present invention can be used for various purposes such as improvement of visibility in a display device such as a reflection type or a reflection / transmission type liquid crystal display device. When it is applied to various devices, it can be arranged at an appropriate position of a display main body such as a liquid crystal cell.

[0045]

EXAMPLE 1 Trifluoroethyl acrylate 90 having a refractive index of 1.40
Parts (parts by weight, hereinafter the same) and a crosslinking agent 10 having a refractive index of 1.48
Parts and a photoreaction initiator in 5 parts are cured by an ultraviolet ray, and the sheet having a refractive index of 1.41 has a tilt angle (θ ₁ , θ ₄ ) of 10 ° and 87 ° on one surface. Aluminum was vacuum-deposited to a thickness of 100 nm, which is equivalent to a plane, on the prism-forming surface of a prism array sheet in which triangular prisms are formed adjacently at a pitch of 30 μm in stripes. At that time, as a result of disposing the polycarbonate sheet parallel to the evaporation source,
A vapor deposition layer having a thickness of about 100 nm was formed on a surface having a tilt angle of 10 degrees, showing good light reflectivity, and a vapor deposition layer having a thickness of only a few nm was formed on a surface having a tilt angle of 87 degrees. One showing light transmissivity was obtained.

When the prism type semi-transmissive reflection plate is arranged on the back of a commercially available super twist type liquid crystal display device and vertical light is incident from the liquid crystal display device side, the brightest reflected image in the direction inclined by 20 degrees is obtained. It was visually recognizable, and was in a good visual recognition state without being affected by surface reflection.

Further, a commercially available EL type backlight is disposed on the back of the above-mentioned prism type semi-transmissive reflection plate to form an illumination device,
When it was turned on, it was confirmed that light was transmitted from the surface having an inclination angle of 87 degrees, and it was confirmed that the device functioned well as a transflective reflector.

Example 2 A prism type transflective plate was obtained in the same manner as in Example 1 except that silver was vapor-deposited instead of aluminum, and an illuminating device was obtained using the same. This means that the reflectance in the reflection mode is excellent due to the improvement of the reflectivity of about 10% by silver, and also in the transmission mode, light is transmitted from the surface having an inclination angle of 87 degrees and functions well as a transflective reflector. Was confirmed.

Example 3 A commercially available light guide plate type backlight, in which emitted light shows directivity in the direction of a surface having an inclination angle of 87 degrees of prismatic irregularities, was used in place of the EL type backlight in Example 1 A lighting device was obtained according to the procedure. In this case, light emitted by the light guide plate type backlight was incident on the surface at an inclination angle of 87 degrees in a state almost perpendicular to the surface, and the brightness in the transmission mode was excellent.

Example 4 A buried layer having a refractive index of 1.60, a haze of 30%, and a thickness of 300 μm made of polycarbonate containing silica fine particles having an average particle size of 5 μm was provided on the prism surface of the semi-transmissive reflection plate. A lighting device was obtained according to Example 3. This is because the transmitted light due to the 87-degree plane was diffused in the buried layer, the directivity was reduced, and the luminance in the vertical direction of the reflector in the transmission mode was excellent. Further, even in the reflection mode, the directivity of the reflected light was reduced, and the luminance in the vertical direction of the reflector was excellent.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a sectional view of another embodiment.

FIG. 3 shows still another embodiment (a liquid crystal display device).
Cross section of

FIG. 4 is a graph showing the reflection characteristics of the transflector.

FIG. 5 is a graph showing reflection characteristics when a light scattering layer is added to the transflective plate.

[Explanation of symbols]

 1: Transflective reflector 11: Transparent substrate 12: Metallized layer 13: Light reflecting surface 14: Light transmitting surface 2, 21: Buried layer 22: Light scattering particles 3: Surface light source 4: Liquid crystal cell

Claims (6)

[Claims] 1. A transparent substrate having a repeating structure of prismatic irregularities, wherein a metal deposition layer is provided on the prismatic irregularities, and a light reflecting surface and a light transmitting surface are formed based on the projections of the prismatic irregularities. And a prism type semi-transmissive reflector. 2. The prism type semi-transmissive reflection plate according to claim 1, wherein the light transmission surface has an inclination angle of 45 degrees or more with respect to a horizontal plane of the transparent substrate. 3. A prism according to claim 1, further comprising: a buried layer on the prism-shaped uneven surface to fill the concave portion, wherein the refractive index of the embedded layer is larger than the refractive index of the material forming the prism-shaped unevenness. Type transflective reflector. 4. The prism type semi-transmissive reflection plate according to claim 3, further comprising a light scattering layer as a buried layer on the prismatic uneven surface or as an arrangement layer on the buried layer. 5. The prism type transflective plate according to claim 4, wherein the light scattering layer is a resin layer or an adhesive layer containing particles having an average particle size of 50 μm or less. 6. A surface light source which exhibits directivity to the light transmitting surface of the prismatic irregular surface on the side of the prism type semi-transmissive reflecting plate according to claim 1 opposite to the prismatic irregularity forming surface. A lighting device, comprising: