JP2003066445A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-illuminative and outside light-illuminative (dually illuminative) liquid crystal display device provided with a translucent and reflective layer, which is made so thin and lightweight that it is difficult to be achieved in the case of the liquid crystal display having a side light type light guide plate and has excellent display quality. SOLUTION: This liquid crystal display device has a liquid crystal display panel (1) provided with at least a liquid crystal cell formed by using a rear side substrate and a visible side substrate each of which is prepared by forming at least a transparent layer (14 or 24) of the refractive index lower than that of a transparent substrate (10 or 20) and the translucent and reflective layer (11) for transmitting and reflecting light or a transparent electrode (21) on the substrate (10 or 20). This display has also illuminators (5) arranged on two or more side faces of the panel (1) and optical path controlling layers (4, 41). The layer (4 or 41) has the refractive indexes higher than that of the layer (14 or 24) and a plurality of optical path changing slopes (A1, B1) which are formed on the outsides of the rear side substrate or the visible side substrate and each of which has 35-48 deg. angle of inclination with respect to the reference plane of the rear side substrate or the visible side substrate. The illuminators (5) are arranged at least on the different side faces of the panel (1), namely, on the side face of each of the substrates (10 and 20).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external light / illumination type liquid crystal display device which is easy to be thin and lightweight and has excellent display quality.

[0002]

BACKGROUND OF THE INVENTION External light / illumination type liquid crystal display devices incorporating a semi-transmissive reflective layer such as a half mirror have been widely used as portable devices such as portable personal computers and mobile phones. In such portable devices, there is a strong demand for weight reduction by downsizing, thinning, and the like in order to further enhance portability. However, even if a sidelight type light guide plate, which has been excellent in thinness in the past, is used as an example of a backlight that can be visually recognized in an illumination mode, the thickness is usually 2 mm or more, and the overall thickness and weight of the device can be reduced. This is the limit.

In view of the above, light is made incident from the side surface of a liquid crystal display panel provided with an optical film having a light emitting means on the viewing side surface of a liquid crystal cell, and the transmitted light in the panel is transmitted by the light emitting means. A reflection type liquid crystal display device for both external light and illumination which is adapted to illuminate the panel through reflection has been proposed (Japanese Patent Laid-Open No. 2000-147499). This is an illumination system for a liquid crystal display panel realized by using an optical film much thinner than the side light type light guide plate, thereby achieving a reduction in thickness and weight.

However, with the recent thinning of the cell substrate, the incident efficiency of light from the side surface of the panel is significantly reduced, and there is a problem that the display brightness is poor. There is also a problem that it is difficult to make the luminance distribution uniform when the light transmission distance in the lateral direction is long with respect to the thickness of the cell substrate, that is, when the area is relatively large. Such a problem also applies to an external light / illumination type liquid crystal display device incorporating a semi-transmissive reflective layer.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides an external light provided with a semi-transmissive reflective layer, which can realize a thin and lightweight structure which is difficult to achieve with a sidelight type light guide plate, and which is excellent in display brightness and its uniformity and has good display quality.・ Developing a dual-purpose lighting LCD device.

[0006]

According to the present invention, there is provided a transparent substrate having at least a transparent layer having a refractive index lower than that of the substrate and a semi-transmissive reflective layer for transmitting and reflecting light, and a transparent substrate having a transparent substrate more than the substrate. Two or more side surfaces in a liquid crystal display panel including at least a liquid crystal cell in which a liquid crystal cell is sandwiched between a viewing-side substrate having at least a transparent layer having a low refractive index and a transparent electrode, the electrode sides facing each other. And a plurality of optical path changing slopes having an inclination angle of 35 to 48 degrees with respect to a reference plane of the substrates on the outside of the back side substrate and the viewing side substrate, and the nearest low refractive index transparent substrate. An optical path control layer having a higher refractive index than the layer is provided,
The present invention provides a liquid crystal display device, characterized in that the illuminating device is arranged at least on the side surfaces of the back side and the viewing side of the respective substrates, and on different side surfaces of the liquid crystal display panel.

[0007]

According to the present invention, a backlight mechanism can be formed by an optical path control layer which is excellent in side surface arrangement and thinness of an illuminating device, and can be arranged on the side surface of a panel by utilizing both the visible side and rear side cell substrates. While efficiently transmitting the incident light from the lighting device in the opposite side direction, the transmitted light is efficiently converted to the viewing side of the liquid crystal display panel through the optical path control layer disposed on the viewing side and the back side for illumination. It can be used for mode liquid crystal display, and it can also achieve liquid crystal display in the external light mode through the semi-transmissive reflective layer. It is excellent in thinness and lightness, and it is bright and excellent in its uniformity, and it has excellent display quality. It is possible to obtain an illumination type liquid crystal display device.

The above are low-refractive-index transparent layers provided on both the viewing-side and back-side cell substrates, an oblique-path-type optical path control layer,
And by using the semi-transmissive reflective layer. That is, the incident light from the side surface of the panel can be efficiently transmitted to the opposite side surface by the confinement effect by the total reflection based on the low refractive index transparent layer, the uniformity of the brightness on the entire screen is improved, and the good display quality is obtained. To be achieved. If the transparent layer with a low refractive index is not provided, the rearward transmission efficiency is poor, and the farther away from the lighting device, the darker the screen becomes and the display becomes difficult to see.

On the other hand, the optical path control layer can reflect the incident light or the transmitted light from the side surface through the optical path conversion slope, can change the optical path with good directivity, and can achieve a thin structure. It is difficult to achieve the above-mentioned directivity by the scattering reflection method via a rough surface or the like. Further, by combining the optical path control layer and the liquid crystal display panel, it is possible to provide an extremely thin light emitting means which is difficult to achieve with the conventional sidelight type light guide plate.
Incidentally, it is also possible to form an optical path control layer having a thickness of 200 μm or less, especially 100 μm or less.

On the other hand, by using the semi-transmissive reflective layer, it is possible to achieve a liquid crystal display having excellent brightness in both the illumination mode and the external light mode by balancing the transmittance and the reflectance.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display device according to the present invention includes a transparent substrate, a rear substrate having at least a transparent layer having a refractive index lower than that of the transparent substrate, and a semi-transmissive reflective layer for transmitting and reflecting light. A liquid crystal display panel including at least a liquid crystal cell in which a liquid crystal cell is sandwiched between a viewing side substrate having at least a transparent layer having a lower refractive index than that substrate and a transparent electrode, and the electrode sides thereof are opposed to each other. Two
The illuminating device is provided on the above side surface, and a plurality of optical path changing slopes having an inclination angle of 35 to 48 degrees with respect to the reference plane of the substrates are provided outside the back side substrate and the viewing side substrate, and the nearest low refractive index. An optical path control layer having a refractive index higher than that of a transparent layer having a refractive index is provided, and the lighting device is disposed at least on the side surfaces of the respective substrates on the back side and the viewing side, and on different side surfaces of the liquid crystal display panel. It is a thing.

An example of the above-mentioned liquid crystal display device is shown in FIG. Reference numeral 1 is a liquid crystal display panel, and 4 and 41 are optical path control layers.
1, B1 is an optical path changing slope, and 10 is a rear transparent substrate,
Reference numeral 11 is a semi-transmissive reflective layer that may also serve as an electrode, 14 is a low refractive index transparent layer, 20 is a transparent substrate on the viewing side, 21 is a transparent electrode, 24 is a low refractive index transparent layer, 30 is a liquid crystal, 5 5,
2 is a lighting device. In addition, 12 and 22 are alignment films, 15,
Reference numeral 25 is a polarizing plate, 16 and 26 are retardation plates, 23 is a color filter, and 6 is a light reflection layer.

As the liquid crystal display panel 1, as shown in the drawing, a rear substrate (10) having at least a transparent substrate 10 having a transparent layer 14 having a lower refractive index than the substrate and a semi-transmissive reflective layer 11 for transmitting and reflecting light. ), And a viewing-side substrate (20) having at least a transparent layer 24 having a lower refractive index than the transparent substrate 20 and the transparent electrode 21 on the transparent substrate 20.
At least a liquid crystal cell having a liquid crystal 30 sandwiched between the first and the second side facing each other is provided, and incident light from the back side is emitted as display light from the other viewing side through control by the liquid crystal or the like. Any suitable material can be used, and the type thereof is not particularly limited. Note that reference numeral 31 in the figure is a sealing material for enclosing the liquid crystal 30 between the transparent substrates 10 and 20.

Incidentally, specific examples of the above-mentioned liquid crystal cell include twist type, non-twist type, guest host type such as TN liquid crystal cell, STN liquid crystal cell, vertical alignment cell, HAN cell, OCB cell based on the alignment form of liquid crystal. And ferroelectric liquid crystals, and those that utilize light diffusion.
The liquid crystal drive system may be an appropriate system such as an active matrix system or a passive matrix system.

A transparent substrate is used for the cell substrate on the viewing side or the back side in order to allow transmission of illumination light or display light. The transparent substrate can be made of an appropriate material such as glass or resin, and is preferably made of an optically isotropic material in view of suppressing birefringence as much as possible and reducing optical loss. . Further, from the viewpoint of improving the brightness and display quality, it is preferable to use one having excellent colorless transparency such as a non-alkali glass plate with respect to a blue glass plate, and a resin substrate is preferable from the viewpoint of lightness and the like.

The low-refractive-index transparent layers provided on both the back-side substrate and the viewing-side substrate are intended to improve the uniformity of brightness on the entire display screen. That is, by providing a layer having a lower refractive index than the transparent substrate forming the substrate on the back side or the viewing side, the incident light from the illumination devices 5, 52 is reflected on the back side as shown by broken line arrows β1 and β2 in FIG. When transmitted inside the substrate 10 or the viewing-side substrate 20, the transmitted light is totally reflected through the refractive index difference between the back-side substrate 10 and the transparent layer 14 or the viewing-side substrate 20 and the transparent layer 24 to cause the back surface. Efficiently confined within the substrate on the viewing side or the viewing side.

As a result, the transmitted light is efficiently transmitted to the opposite side surface (rear side), and the transmitted light is evenly distributed to the optical path conversion slopes A1 and B1 of the optical path control layers 4 and 41 at positions far from the illumination device. It is supplied well and the light path is changed through the reflection by the inclined surface as shown by the polygonal arrows α1 and α2 to improve the uniformity of brightness on the entire display screen.

Further, in the low refractive index transparent layer, the transmitted light is incident on the liquid crystal layer and is subjected to birefringence and scattering, whereby the transmitted state is partially changed and the transmitted light is reduced or nonuniform. It is also intended to prevent the display from being darkened and to prevent the display near the lighting device from becoming a ghost in the rear to deteriorate the display quality.

Further, the transparent layer having a low refractive index is also intended to prevent abrupt attenuation due to absorption of transmitted light due to the arrangement of a color filter or the like, thereby avoiding a decrease in transmitted light. In the case where the incident light from the lighting device is transmitted through the liquid crystal layer, the transmitted light is scattered in the liquid crystal layer and becomes a non-uniform transmission state, making the output light non-uniform and ghosts, making the displayed image difficult to see. Cheap.

The low-refractive-index transparent layer is formed by vacuuming an appropriate material such as an inorganic or organic low-refractive-index dielectric material having a lower refractive index than the transparent substrate forming the backside or viewing side substrate. It can be formed by an appropriate method such as a vapor deposition method or a spin coating method, and there is no particular limitation on the material and the forming method. The larger the difference in refractive index between the transparent layer and the transparent substrate is, the more advantageous it is from the viewpoint of the rearward transmission efficiency due to the above-mentioned total reflection. Particularly, it is preferably 0.05 or more, particularly 0.1 to 0.4. preferable.

The above-mentioned difference in refractive index has almost no effect on the display quality in the external light mode. By the way, when the refractive index difference is 0.1, the reflectance of external light at the interface is 0.1% or less, and the decrease in brightness and contrast due to the reflection loss is extremely small.

The arrangement position of the transparent layer having a low refractive index can be appropriately determined, but in view of the effect of confining the transmitted light and the prevention of intrusion into the liquid crystal layer, the transparent substrates 10 and 20 as shown in FIG.
It is preferably located between the semi-transmissive reflective layer 11 and the transparent electrode 21. When the color filter 23 is arranged between the transparent substrates 10 and 20 and the semi-transmissive reflective layer 11 or the transparent electrode 21, the substrate 1 is more preferable than the color filter because it prevents absorption loss of transmitted light due to the color filter.
It is preferably located on the 0, 20 side. Therefore, as a rule,
The low refractive index transparent layers 14 and 24 are directly provided on the rear transparent substrate 10 or the visible transparent substrate 20.

In the above case, the smoother the surface of the substrate on which the transparent layer is attached, and the smoother the transparent layer is, the more advantageous in preventing the scattering of transmitted light, and the more preferable in terms of preventing the influence on the display light. In the case of the above-mentioned point, it is preferable that the color filter 23 is located on the viewing side substrate 20 side as in the example of FIG.

If the thickness of the transparent layer having a low refractive index is too thin, the confinement effect described above may be diminished due to the phenomenon of wave bleeding. Therefore, it is more advantageous to maintain the total reflection effect. The thickness can be appropriately determined in view of the total reflection effect and the like. In general, from the viewpoint of total reflection effect on visible light having a wavelength of 380 to 780 nm, particularly light having a wavelength of 380 nm on the short wavelength side, a quarter wavelength (95 nm) based on the optical path length calculated by the refractive index x layer thickness. Above all, half wavelength (19
The thickness is preferably 0 nm) or more, more preferably 1 wavelength (380 nm) or more, and further preferably 600 nm or more.

The thickness of the cell substrate 10 or 20 on the back side or the viewing side is not particularly limited and can be appropriately determined according to the strength of liquid crystal filling. Generally, from the viewpoint of the balance between the incident efficiency and the transmission efficiency of the incident light from the lighting device as a transmission substrate and the thinness and lightness, 10 μm to 5 mm, especially 50
The thickness is from μm to 2 mm, especially from 100 μm to 1 mm.

The thickness of the transparent substrate on the back side and the thickness of the transparent substrate on the viewing side may be the same or different. The transparent substrate may be the same thickness plate, or for the purpose of improving the incidence efficiency of the transmitted light on the optical path conversion slope by the inclined arrangement of the optical path control layer,
It may have a partially different thickness such as a wedge-shaped cross section.

Further, the transparent substrate on the rear side and the transparent substrate on the visible side may have the same plane dimension or may have different plane dimensions. Rather than using the back side and viewing side substrates as transmission substrates for incident light from the lighting device, the back side substrate 10 (or the viewing side substrate 20) is provided on the side surface on which the lighting devices 5 and 52 are arranged as shown in the figure. It is preferable that the side surface formed by the viewing-side substrate (or the back-side substrate) is projected more than the side surface formed by (1) from the viewpoint of incidence efficiency when the illumination device is arranged on the protruding side surface.

The semi-transmissive reflection layer provided on the transparent substrate on the rear side transmits the backlight light α2 from the rear side in the illumination mode and reflects the front light light α1 from the viewing side as in the example of FIG. At the same time, it is intended to reflect incident external light in the external light mode. This makes it possible to realize a liquid crystal display device for both external light and illumination.

The semi-transmissive reflective layer can be formed as an appropriate layer that transmits and reflects light, such as a half mirror or a reflective layer having an opening. Above all, a metal thin film such as a half mirror or a metal layer provided with an opening is preferable from the viewpoint of maintaining the function in the liquid crystal cell.

The ratio between the light transmittance and the reflectance of the semi-transmissive reflective layer can be appropriately determined by the balance of brightness in the illumination mode and the external light mode. Generally, the transmittance is 5 to 95%, especially 15 to 85%, and particularly 25 to 75%. By the way, in the half mirror system described above, the film thickness is controlled, and in the aperture system, the occupancy of the aperture is controlled, whereby the ratio of the light transmittance and the reflectance can be changed.

When the semi-transmissive reflective layer is formed by the above-mentioned aperture method, the pixel size of the liquid crystal cell is 5 to 95.
%, Especially 15 to 85%, especially 25 to 75% of the openings are preferably distributed in correspondence with the arrangement of pixels as much as possible from the viewpoint of improving the uniformity of brightness on the display screen.
The semi-transmissive reflective layer having an opening can be formed by an appropriate method such as a punching method of a reflecting plate, an etching method of a reflecting layer, or a method of depositing a reflecting material through a mask provided with a predetermined opening.

The semi-transmissive reflective layer is formed so as to scatter and reflect incident external light on the uneven surface in order to improve the utilization efficiency of external light or improve the uniformity of brightness in the external light mode. It is preferable. When the semi-transmissive reflective layer is made of a thick film such as a metal foil, the uneven light-scattering surface can be formed by a method of treating the surface by a roughening method such as buffing.

On the other hand, in the case of a semi-transmissive reflective layer formed of a thin film by a vapor deposition method or the like, for example, a method of forming a thin film reflecting the unevenness by using the surface of a transparent substrate as a light-scattering surface of the uneven surface is used. A semi-transmissive reflective layer capable of being scattered and reflected can be formed. At this time, from the viewpoint of maintaining the smoothness of the low-refractive-index transparent layer, it is preferable to provide the low-refractive-index transparent layer using a transparent substrate having a smooth surface, and to provide the layer having the surface uneven structure thereon.

In the case of the latter method described above, the front and back surfaces of the semi-transmissive reflection layer are scattering reflection surfaces, and therefore, there is an advantage that the display quality can be improved. That is, in the illumination mode, when the transmission light inside the substrate undergoes optical path conversion and reaches the semi-transmissive reflection layer, it is scattered and reflected by the front and back surfaces thereof, and the transmission distance is shortened. Also, most of the transmitted light transmitted through the semi-transmissive reflective layer is
It is confined inside the substrate on the side opposite to the viewing side or the back side to prevent emission, or is prevented from being emitted due to absorption by the liquid crystal layer, the color filter layer, or the like and generation of a phase difference.

As a result of the above, it is possible to prevent the transmitted light from abruptly decreasing due to absorption by the semi-transmissive reflective layer and the drive circuit. In addition, the display becomes dark due to the reduction of transmitted light and the occurrence of non-uniformity due to the partial change due to the birefringence of the liquid crystal layer due to the transmission of the semi-transmissive reflective layer and the light scattering. It is possible to suppress the occurrence of a ghost phenomenon that affects the rear side. The same applies to the case of the aperture type semi-transmissive reflective layer.

The semi-transmissive / reflecting layer can be provided also as an electrode forming a circuit for driving a liquid crystal. FIG. 1 shows an example thereof. Further, a transparent electrode forming a circuit for driving a liquid crystal can be provided separately from the semi-transmissive reflective layer. In the latter case, when a transparent electrode is provided on the semi-transmissive reflective layer having an uneven light-scattering surface, it is preferable that the transparent electrode is not uneven.

To prevent the above-mentioned unevenness of the transparent electrode, for example, a transparent insulating layer having a smooth surface for leveling is provided on a semi-transmissive reflective layer having an uneven light-scattering surface, and the transparent electrode is provided thereon. It can be performed by a forming method or the like.
The transparent insulating layer can be formed by an appropriate method such as a transparent resin coating layer. In addition, the liquid crystal display device,
It can also be formed by providing a liquid crystal driving circuit between the transparent layer having a low refractive index and the semi-transmissive reflective layer on the rear substrate.

The transparent substrate on the visible side and, if necessary, the transparent electrode provided on the transparent substrate on the back side can be formed of an appropriate material in accordance with the prior art such as ITO. When forming a liquid crystal cell, one or more layers of suitable functional layers such as an alignment film made of a rubbing film for aligning liquid crystals and a color filter for color display may be provided, if necessary. .

As shown in the drawing, the alignment films 12 and 22 are usually formed on the electrodes 11 and 21 so as to be in contact with the liquid crystal, and the color filter 23 is usually formed on the cell substrate 1.
It is provided between the transparent substrate and the electrode on one of 0 and 20. In the illustrated example, the color filter 23 is provided on the viewing side substrate 20.
Is provided.

The liquid crystal display panel includes one or more suitable optical layers such as polarizing plates 15 and 25, retardation plates 16 and 26, and a light diffusing layer in the liquid crystal cell as shown in the examples of FIGS. It may be added if necessary. The polarizing plate is intended to achieve display using linearly polarized light, and the retardation plate is intended to improve display quality by compensating for retardation due to birefringence of liquid crystal.

The light diffusing layer expands the display range by diffusing the display light, equalizes the brightness by leveling the bright line emission through the optical path conversion slope of the optical path control layer, and diffuses the transmitted light in the liquid crystal display panel. The optical path control layer 4 on the back side and the polarizing plate 2 on the viewing side for the purpose of increasing the amount of light incident on the optical path control layer due to
One layer or two or more layers can be arranged at an appropriate position between 5.

As the polarizing plate, an appropriate one can be used without any particular limitation. Rather than obtaining a good contrast ratio display due to the incidence of highly linearly polarized light,
For example, a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene / vinyl acetate copolymer partially saponified film is adsorbed with a dichroic substance such as iodine or a dichroic dye and stretched. An absorptive polarizing film made of the above, or a film having a high degree of polarization such as a film having a transparent protective layer provided on one side or both sides thereof can be preferably used.

For forming the transparent protective layer, those having excellent transparency, mechanical strength, thermal stability and moisture shielding property are preferably used. Examples include acetate-based resins and polyester-based resins, polyethersulfone-based resins and polycarbonate-based resins, polyamide-based resins and polyimide-based resins, polyolefin-based resins and acrylic-based resins, polyether-based resins, polyvinyl chloride, and styrene-based resins. Examples thereof include polymers such as and norbornene resins, and thermosetting or ultraviolet curing resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone resins.

The transparent protective layer can be provided by an adhesive method of a film or a coating method of polymer liquid or the like. Therefore, the technique for forming such a transparent protective layer can be applied to the formation of the above-mentioned transparent insulating layer.

On the other hand, as the retardation plate, a birefringent film or a nematic film obtained by subjecting a film made of a suitable polymer such as those exemplified in the above-mentioned transparent protective layer to a stretching treatment by a suitable method such as uniaxial or biaxial. An appropriate film such as an oriented film of an appropriate liquid crystal polymer such as a system or discotic type, or an oriented film in which the oriented layer is supported by a transparent substrate can be used. It may be one in which the refractive index in the thickness direction is controlled under the action of the heat shrinkage force of the heat shrinkable film.

The retardation plates 16 and 26 for compensation are usually arranged between the polarizing plates 15 and 25 on the viewing side and / or the rear side and the liquid crystal cell as necessary as shown in the drawing, and the retardation plates are provided on the retardation plates. May be appropriately selected depending on the wavelength range and the like. Further, the retardation plate may be used by superposing two or more layers for the purpose of controlling optical characteristics such as retardation.

The light diffusing layer can also be provided by an appropriate method using a coating layer having a surface fine uneven structure or a diffusing sheet. The light diffusing layer can be formed as a pressure-sensitive adhesive layer containing transparent particles and also as a layer that also serves as an adhesive for a polarizing plate and a retardation plate, thereby making it possible to reduce the thickness. To form the adhesive layer, a rubber-based, acrylic-based, vinyl alkyl ether-based, silicone-based, polyester-based, polyurethane-based, polyether-based, polyamide-based, styrene-based, or other suitable polymer-based adhesive is used as a base polymer. Can be used.

Among them, those having excellent transparency, weather resistance, heat resistance and the like are preferably used, such as an acrylic pressure-sensitive adhesive whose base polymer is a polymer mainly composed of an alkyl ester of acrylic acid or methacrylic acid. The transparent particles that may be added to the adhesive layer include, for example, silica or alumina having an average particle size of 0.5 to 20 μm, titania or zirconia, tin oxide or indium oxide, conductive material such as cadmium oxide or antimony oxide. One kind or two kinds of appropriate particles such as inorganic particles which may have properties and organic particles composed of a crosslinked or uncrosslinked polymer can be used.

The illuminating device arranged on the side surface of the liquid crystal display panel aims to make light used as illumination light of the liquid crystal display device incident from the side surface of the liquid crystal display panel. This makes it possible to reduce the thickness and weight of the liquid crystal display device in combination with the optical path control layers arranged on both sides of the panel. Any appropriate lighting device can be used. By the way, as an example, a linear light source such as a (cold, heat) cathode tube, a point light source such as a light emitting diode, an array body in which they are arranged in a linear or planar shape, or a combination of a point light source and a linear light guide plate Illumination device and the like which converts incident light from a point light source into a linear light source through a linear light guide plate.

As shown in the example of FIG. 1, the illuminating devices 5 and 52 are arranged at least on two or more different side surfaces of the liquid crystal display panel, and are arranged separately from the viewing side substrate and the rear side substrate. . The plurality of side surfaces may be a combination of side surfaces that face each other as in the example of FIG. 1, a combination of side surfaces that intersect in the vertical and horizontal directions, or a combination of three or more side surfaces that use them in combination. . This different side surface arrangement method can prevent mechanical interference of the light source position. Further, by turning on / off the illumination devices independently, it is possible to control the illumination or extinction of each illumination device to change the brightness stepwise. Note that the lighting device can be arranged on a plurality of side surfaces of the same substrate.

The method of arranging the illuminating device on the opposite side surfaces as in the example of FIG. 1 mutually complements the angular characteristics of the emitted light, and also complements the phenomenon of brightness on the opposite end side farther from the illuminating device. Therefore, it is more advantageous in terms of improving the brightness and improving the uniformity of the brightness on the entire screen. Further, in that case, by making the side surface of the substrate on which the lighting device is arranged project more than the side surface formed by the other substrate as shown in the above-described example, the workability of arranging the lighting device and the work of surrounding and holding by the light source holder are also improved. It is also possible to prevent incident light from the lighting device from entering the liquid crystal layer.

The lighting device enables visual recognition in the lighting mode by turning on the lighting device. Since the external light / illumination dual type does not require lighting when visually recognized in the external light mode by external light, it is possible to switch between lighting and extinguishing. As the switching method, any method can be adopted, and any conventional method can be adopted. The illuminating device may be of a different color emission type capable of switching emission colors, or may be of a type capable of emitting different color light through different types of illuminating devices.

As shown in the figure, for the lighting devices 5 and 52,
In order to guide the divergent light to the side surface of the liquid crystal display panel as required, a combination body in which an appropriate auxiliary means such as a light source holder 51 surrounding it is arranged may be used. As the light source holder, for example, a resin sheet or a white sheet provided with a metal thin film having high reflectance, a metal foil, a resin molded product, or the like, and an appropriate reflection sheet at least the light reflecting the light can be used.

The light source holder can also be used as a holding means that also serves as an enclosure for the lighting device. In that case, the illumination device can be surrounded and held by a method of adhering the end portion of the light source holder to the end portions of the upper and lower surfaces of the substrate on the back side or the viewing side. It is also possible to apply a method of surrounding and holding the illuminating device, such as a method of adhering in a state of extending from the end of the upper surface of the viewing side substrate to the end of the lower surface of the back side substrate through the end of the light source holder.

The optical path control layer 4 arranged on the rear surface side makes incident light from the illuminating device 5 arranged on the side surface of the liquid crystal display panel 1 or transmitted light thereof, as shown by an arrow α2 in FIG. For the purpose of converting the optical path to the viewing side of the panel through and using it as illumination light (display light),
It is arranged outside the rear substrate 10 of the liquid crystal display panel 1.

On the other hand, the optical path control layer 41 arranged on the viewing side.
As shown by the arrow α1 in FIG. 1, the incident light from the illumination device 52 arranged on the side surface of the liquid crystal display panel 1 or its transmitted light is converted to the rear surface side of the panel via the optical path conversion slope B1. It is arranged on the outside of the viewing side substrate 20 of the liquid crystal display panel 1 for the purpose of being reflected and moved backward by the semi-transmissive reflection layer 11 and used as illumination light (display light).

For the above-mentioned purpose, the optical path control layers 4 and 41 are substrates on the back side or the viewing side in order to reflect the incident light from the illuminating devices 5 and 52 and change the optical path in a predetermined direction as in the example of FIG. Angle of inclination with respect to the reference plane (virtual horizontal plane) of 35 to 4
It is assumed to have the optical path changing slopes A1 and B1 of 8 degrees.

The optical path control layer has a plurality of the optical path conversion slopes for the purpose of thinning. Further, the optical path control layer is formed as a layer having a higher refractive index than the nearest transparent layer having a low refractive index provided on the back side or the viewing side substrate.
When the refractive index of the optical path control layer is lower than that of the transparent layer, the incident light from the lighting device or its transmitted light is easily trapped in the substrate on the back side or the viewing side, and the incidence on the optical path control layer is hindered and displayed. It becomes difficult to use it as light.

The optical path control layer can be formed in an appropriate form except that it has a plurality of predetermined optical path conversion slopes. From the point of obtaining the display light having excellent directivity in the front direction through the optical path conversion or the like, the light emitting means A and B including the optical path conversion slopes A1 and B1 facing the side surface on which the illuminating device is arranged, that is, the incident side surface is provided. Light emitting means A and B having a plurality of optical path control layers 4 and 41, in particular, optical path conversion slopes A1 and B1 formed of prismatic irregularities.
An optical path control layer having a plurality of

An example of the light emitting means having the above-mentioned optical path changing slope or prismatic unevenness is shown in FIGS. 3 (a) to 3 (e). In (a) to (c), the light emitting means A has a triangular cross section, and in (d) and (e), it has a quadrangular cross section. Further, (a) has two optical path conversion slopes A1 formed by an isosceles triangle, and (b) has optical path conversion slopes A1.
1 and a light emitting means A having a steep slope A2 whose inclination angle with respect to the reference plane is larger than the slope A1.

In (c), the light emitting means A, which is composed of the optical path changing slope A1 and the gentle slope A2 having a small inclination angle with respect to the reference plane, is formed on the entire surface on one side of the optical path control layer in the adjacent continuous state. (D) has a light emitting means A consisting of convex portions (protrusions), and (e) has a light emitting means A consisting of concave portions (grooves). In FIG. 3, the optical path conversion slope A1 and the steep slope or gentle slope A2 based on the light emitting means A are used.
However, the light emitting means B, and hence the optical path conversion slope B1 and the steep slope or the gentle slope B2 can be formed according to the light emitting means A (the same applies hereinafter).

Therefore, as in the above example, the light emitting means is
It can be formed on a convex portion or a concave portion that is an equilateral surface or a slope having the same inclination angle, or can be formed on a convex portion or a concave portion that is formed by an optical path conversion slope and a steep slope or a gentle slope or a slope having a different inclination angle. The form can be appropriately determined according to the number and position of the incident side surfaces. From the viewpoint of maintaining the slope function by improving scratch resistance, it is advantageous that the slope is less likely to be scratched because the light emitting means is formed of concave portions rather than convex portions.

An optical path control layer more preferable in terms of achieving the above-mentioned characteristics such as directivity in the front direction is an optical path conversion slope A having an inclination angle of 35 to 48 degrees with respect to a reference plane as shown in the figure.
1 and B1 are faced to the incident side surface. Therefore, when the illuminating device is arranged on two or more side surfaces of the same substrate and has two or more incident side surfaces, an optical path control layer having the optical path conversion slopes A1 and B1 corresponding to the number and the position thereof is preferably used. To be

By the way, when the illuminating device is arranged on the two opposite side surfaces of the same substrate, the two light path changing slopes A1 by the light emitting means A and B having the cross section of an isosceles triangle as shown in FIG. B1 and an optical path having two optical path conversion slopes A1 and B1 formed by the light emitting means A and B each having a trapezoidal transverse cross section as shown in FIGS. 3D and 3E, with their ridges extending along the incident side surface. Control layers 4, 41 are preferably used.

Further, when the illuminating device is arranged on the two side surfaces adjacent to each other in the vertical and horizontal directions of the liquid crystal display panel, the optical path conversion slopes A1 and B are formed with the ridge lines corresponding to the side surfaces in both the vertical and horizontal directions.
An optical path control layer having 1 is preferably used. Furthermore, when arranging the illuminating device on three or more side surfaces including facing and vertical and horizontal directions, the optical path conversion slopes A1 and B1 composed of the above combinations are provided.
An optical path control layer having is preferably used.

The above-mentioned optical path changing slopes A1 and B1 reflect the light incident on the surfaces A1 and B1 of the incident light or the transmitted light from the incident side surface through the illuminating device, and the viewing direction of the liquid crystal display panel. It serves to supply light that can be used for panel display by changing the optical path. In that case, the optical path conversion slope A
By setting the inclination angles of 1 and B1 with respect to the reference plane to 35 to 48 degrees, the side incident light or its transmitted light can be converted into a light path with good perpendicularity to the reference plane, as illustrated by the broken line arrows α1 and α2 in FIG. Thus, it is possible to efficiently obtain display light having excellent directivity to the front.

When the inclination angle of the optical path conversion slope is less than 35 degrees, the optical path of the reflected light is largely deviated from the front direction and it is difficult to effectively use it for display, and the brightness in the front direction is poor. When it exceeds 48 degrees, side incident light or its transmission is transmitted. The condition for totally reflecting the light deviates from the condition for causing total reflection of light, and the amount of leaked light from the optical path conversion slope increases, resulting in poor light utilization efficiency of side incident light.

The preferable inclination angles of the optical path conversion slopes A1 and B1 are based on the refraction of the light transmitted through the liquid crystal display panel according to Snell's law from the viewpoints of the optical path conversion excellent in the directivity to the front and the suppression of leakage light. 38-
It is 45 degrees, especially 40 to 44 degrees. By the way, the general condition for total reflection of a glass plate is about 42 degrees. Therefore, in this case, the side incident light is incident on the optical path changing slope while being transmitted while being collected in a range of ± 42 degrees.

A plurality of light emitting means A and B having the optical path changing slopes A1 and B1 are provided as shown in FIGS. 3 and 4 for the purpose of thinning the optical path control layer as described above. In that case,
From the point that the incident light from the incident side surface is reflected backward and is efficiently transmitted to the opposite side surface side to emit light as uniformly as possible over the entire surface of the liquid crystal display, the inclination angle with respect to the reference plane is 10 degrees or less, especially 5 It is preferable that the structure includes gentle slopes A2 and B2 having a degree of 3 degrees or less, or flat planes A3 and B3 having an inclination angle of substantially 0 degree.

Therefore, the steep slope A2 (B) illustrated in FIG. 3 (b) is used.
In the light emitting means A (B) including 2), it is preferable to make the angle of the steep slope 35 degrees or more, particularly 50 degrees or more, and particularly 60 degrees or more so that the width of the flat surface A3 (B3) can be widened. .

As shown in FIGS. 3 and 4, the light emitting means A (B) is provided such that its ridge line is parallel or inclined to the incident side surface of the liquid crystal display panel 1 in which the illuminating device 5 (52) is arranged. . In that case, the light emitting means A (B) may be formed continuously from one end to the other end of the optical path control layer as in the example of FIG. 3, or intermittently discontinuous as in the example of FIG. It may be formed.

When the light emitting means A (B) is discontinuously formed, the depth in the direction along the incident side surface of the unevenness formed by the grooves or protrusions is made deep in view of the incident efficiency of the transmitted light and the optical path conversion efficiency. Alternatively, it is preferable that the height is 5 times or more, and the length is 500 μm in view of uniform light emission on the panel display surface.
Hereafter, it is preferably 10 to 480 μm, particularly preferably 50 to 450 μm. The semi-transmissive reflective layer is omitted in FIGS.

The cross-sectional shape of the light emitting means A and B and the pitch of the optical path changing slopes A1 and B1 passing through them are not particularly limited. Since the optical path conversion slopes A1 and B1 are the factors that determine the brightness in the illumination mode, the optical path conversion slopes A1 and B1 can be appropriately determined according to the uniformity of light emission on the panel display surface, and the optical path conversion light amount can be controlled by the distribution density. .

Therefore, the slope angle and the like of the slope may be constant over the entire surface of the optical path control layer, or the light emission on the panel display surface can be made uniform by coping with absorption loss and attenuation of transmitted light due to the previous optical path conversion. For the purpose of achieving the above, the light emitting means A (B) may be made larger as the distance from the incident side surface is increased as illustrated in FIG.

Further, as shown in FIG. 5, the light emitting means A (B) having a constant pitch can be used, or as shown in FIG. It is also possible to increase the distribution density of the means A (B). Further, the light emission on the panel display surface can be made uniform at random pitches.

In addition, in the case where the light emitting means A and B are unevenness formed of discontinuous grooves or protrusions, the size and shape of the unevenness, the distribution density, the direction of the ridge line, etc. may be irregular.
It is also possible to randomly arrange the irregular or regular or uniform irregularities to achieve uniform light emission on the panel display surface. Therefore, uniform light emission on the panel display surface as in the above example can be achieved by applying an appropriate method to the light emitting means A and B. In addition, in FIGS.
The arrow direction is the transmission direction of the incident light from the incident side surface.

As described above, the light path changing slope is a functional portion for substantially forming illumination light by changing the light path of the side incident light. Therefore, if the interval is too wide, the illumination at the time of lighting becomes sparse and unnatural. It may be displayed. From the viewpoint of prevention, the pitch of the optical path conversion slopes A1 and B1 is 2 mm or less, especially 20.
The thickness is preferably 1 μm to 1 mm, and more preferably 50 μm to 0.5 mm.

On the other hand, the illuminating light passing through the plurality of optical path converting slopes, particularly the optical path converting slopes continuous in the incident side surface direction, may interfere with the pixels of the liquid crystal cell to cause moire. Moire can be prevented by adjusting the pitch of the optical path conversion slope, and the pitch has a preferable range as described above. Therefore, a solution when moire occurs in the above-mentioned preferable pitch range becomes a problem.

In the above case, it is preferable to form moire by forming the ridge lines of the unevenness in a state of being inclined with respect to the incident side surface so that the optical path conversion slopes can be arranged in an intersecting state with respect to the pixels. In that case, if the inclination angle with respect to the incident side surface is too large, the reflection through the optical path conversion inclined surface is deflected, and a large deviation occurs in the direction of the optical path conversion, which is likely to cause deterioration of display quality.

From the viewpoint of preventing the display quality from deteriorating due to the deviation of the optical path changing direction, it is preferable that the inclination angle of the ridge line of the unevenness with respect to the incident side surface is within ± 30 degrees, especially within ± 25 degrees. The sign ± means the inclination direction of the ridgeline with respect to the incident side surface. When the resolution of the liquid crystal cell is low and moiré does not occur or when moiré can be ignored, it is preferable that the ridge line be parallel to the incident side surface.

From the above point, considering that the pixel pitch of the liquid crystal cell is generally 100 to 300 μm, the optical path conversion slope is 40 μm based on the projection width to the reference plane.
In the following, it is preferable that the thickness is 3 to 20 μm, especially 5 to 15 μm. Such a projection width is more preferable than the point that the deterioration of display quality due to diffraction is prevented because the coherent length of the fluorescent tube is generally about 20 μm.

The optical path control layer may be formed of an appropriate material that exhibits transparency depending on the wavelength range of the illuminating device and has a higher refractive index than the transparent layer having a low refractive index. By the way, in the visible light range, the polymers, the curable resins, and the glass exemplified in the above transparent protective layer and the like can be mentioned. An optical path control layer formed of a material that does not exhibit birefringence or has low birefringence is preferable.

Further, from the point of suppressing the amount of lost light that is confined inside the panel due to interface reflection and cannot be emitted, and efficiently supplies the side incident light or its transmitted light to the optical path control layer, especially the optical path conversion slope, the above low refractive index is obtained. The refractive index is 0.05 or more, more preferably 0.08 or more, especially 0.1 to 0.
It is preferably a high optical path control layer.

Further, the incident light from the illuminating device or its transmitted light is efficiently incident on the nearest optical path control layer from the substrate on the rear side or the viewing side to achieve a bright display through the optical path conversion slope, and thus the rear side. Alternatively, the difference in refractive index from the closest substrate on the viewing side is within 0.15, particularly within 0.10, and particularly, 0.
It is preferable that the optical path control layer is within 05, and in particular, the optical path control layer having a refractive index higher than that of the nearest transparent substrate.

As described above, by disposing the optical path control layer and the illuminating device on both the back side substrate and the viewing side substrate, the amount of incident light in the entire liquid crystal display panel can be increased in response to the thinning of the cell substrate. A bright display can be achieved. The optical path control layers arranged on the back side or the viewing side substrate may be the same or different types having the light emitting means of the same form, or different types having the light emitting means of different forms. It may be one.

The optical path control layer can be formed by a cutting method and can be formed by an appropriate method. As a preferable manufacturing method from the viewpoint of mass productivity and the like, for example, a method of transferring a shape by pressing a thermoplastic resin under heat to a mold capable of forming a predetermined shape, a heat-melted thermoplastic resin or heat or a solvent is used. A method of filling a resin that has been fluidized through a mold that can be molded into a predetermined shape, a monomer or oligomer that can be polymerized by heat, ultraviolet rays or radiation, or a liquid resin is filled into a mold that can form a predetermined shape. Or a method of polymerizing by casting.

Further, a method in which the above-mentioned liquid resin or the like which can be polymerized with ultraviolet rays or radiation is applied to the support film in advance, and the coating layer is molded with a mold capable of forming a predetermined shape and polymerized, There is also a method in which a mold capable of forming a predetermined shape is filled with the above liquid resin or the like, a support film is placed on the mold, and ultraviolet rays or radiation is irradiated to perform a polymerization treatment.

In the above case, a transparent support film can be used to form an optical path control layer integrated with the film, or after formation, the optical path control layer can be peeled off from the support film to form a molding layer based on the coating layer or the filling layer. It is also possible to form an optical path control layer consisting of only. In that case, it need not be a transparent film. Peeling can be achieved by, for example, a method of surface-treating the support film with a release agent.

Therefore, the optical path control layer can be formed by directly giving a predetermined form to the back side or the viewing side substrate, or can be formed as a transparent sheet or the like having a predetermined form. Although the thickness of the optical path control layer can be appropriately determined, it is generally 300 μm or less, preferably 5 to 200 μm, and particularly 10 to 100 μm in view of reduction in thickness. The shape such as a trigonal to pentagonal shape based on the cross section of the light emitting means does not mean a strict polygonal shape, and the roundness of the corners and the angle change of the surface based on the manufacturing technology and the like are allowed.

The optical path control layer is disposed on the back side and the viewing side of the liquid crystal display panel. In that case, the slope forming surface, that is, the surface on which the light emitting means A and B are formed is the outer surface side as illustrated in FIG. It is preferable to dispose the light emitting means A and B in terms of the reflection efficiency through the optical path conversion slopes A1 and B1 of the light emitting means A and B, and further from the viewpoint of improving the brightness by effectively utilizing the side incident light.

The optical path control layer, particularly the optical path control layer on the viewing side,
A non-glare treatment or an anti-reflection treatment may be performed for the purpose of preventing visual inhibition due to surface reflection of external light. The non-glare treatment is to make the surface a fine concavo-convex structure by various methods such as a surface roughening method such as a sand blast method or an embossing method, a method of mixing transparent particles such as silica or a method of coating a resin containing transparent particles. The antireflection treatment can be performed by a method of forming an interfering vapor deposition film or the like.

The non-glare treatment and the antireflection treatment can also be applied by the above-mentioned method of adhering a film provided with a surface fine uneven structure or an interference film. The polarizing plates may be provided on both sides of the liquid crystal cell as shown in the figure, or may be provided on only one side of the liquid crystal cell. Further, the above-described surface fine unevenness structuring technique can be applied when the surface of the light diffusion layer, the semi-transmissive reflective layer, and / or the transparent substrate described above is used as the uneven light scattering surface. Further, the above-mentioned transparent particles mixed in the adhesive layer can be used for the above-mentioned non-glare treatment and the like.

When the optical path control layer is independently formed as a transparent sheet or the like as described above, the transparent sheet or the like has a refractive index higher than that of the nearest transparent layer 14 or 24 having a low refractive index as described above. Through the adhesive layers 18 and 28, and in particular, the adhesive layer having the same refractive index as that of the transparent sheet or the like, especially the intermediate adhesive layer between the transparent sheet or the like and the transparent substrate on the back side or the viewing side. Adhesion to the liquid crystal display panel is preferable from the standpoint of improving brightness by effectively utilizing side incident light.

Therefore, the refractive index of the adhesive layer can be similar to that of the optical path control layer described above. Therefore, the refractive index of the optical path control layer and the adhesive layer is preferably higher than that of the nearest transparent layer having a low refractive index by 0.05 or more. The adhesive layer can be formed with an appropriate transparent adhesive, and the type of the adhesive is not particularly limited. The adhesive method using an adhesive layer is preferable from the viewpoint of simplicity of the adhesive treatment work. The adhesive layer can be based on the above, and the above-mentioned light diffusion type adhesive layer can also be used.

As in the example shown in FIG. 1, a light reflection layer 6 can be disposed outside the optical path control layer 4 on the back side, if necessary. Such a light-reflecting layer is reflected and inverted again by the light-reflecting layer that the light reflected through the optical path control layer on the back side is reflected and inverted by the semi-transmissive reflecting layer inside the liquid crystal cell and cannot be emitted. The purpose is to return to the direction of the liquid crystal cell to improve the light utilization efficiency and thus the brightness.

Further, the light transmitted through the semi-transmissive reflective layer of the reflected light through the optical path control layer on the viewing side and the external light transmitted through the semi-transmissive reflective layer in the external light mode are reflected and inverted to return to the liquid crystal cell direction, It is also effective in improving the light utilization efficiency and, in turn, the brightness. Further, it is also effective in improving the light use efficiency by reflecting and inverting the leaked light from the optical path control layer on the back side and re-incident it.

The light-reflecting layer can be formed of an appropriate material such as a white sheet according to the related art. Above all, for example, a coating layer in which a powder of a metal or an alloy thereof having a high reflectance such as aluminum, silver, gold, copper, chromium, etc. is contained in a binder resin, the above metal, etc. and a dielectric multilayer film are vacuum deposited. Layer with a thin metal film attached by an appropriate thin film forming method such as a sputtering method or a sputtering method, a reflection sheet in which the coating layer or the additional layer is supported by a base material such as a film, and a high reflectance including a metal foil The light-reflecting layer, particularly, the light-reflecting layer having at least a metal thin film is preferable in terms of reflection efficiency. The technique for forming such a light reflection layer can be applied to the formation of the above-mentioned semi-transmissive reflection layer.

The light reflecting layer may be closely attached to the back surface of the optical path control layer on the back surface side without a gap. The formation of the light-reflecting layer in close contact with no space is performed by, for example, a method of vacuum-depositing a metal thin film on the optical path control layer, a method of adhering a film-like flexible light-reflecting layer in accordance with the shape of the optical path control layer, and the like. be able to. In the latter case, the refractive index of the adhesive layer is preferably smaller than that of the optical path control layer, because transmitted light can be efficiently transmitted by total reflection based on the difference in the refractive index of the interface.

Further, the light reflection layer is in a state in which it is in close contact with the back surface of the light path control layer apart from the light emitting means A of the light path control layer 4 on the back surface side as in the example of FIG. Can also be provided. In order to form the light-reflecting layer in such a manner that the air layer is interposed between the light-path control layer and the light-reflecting layer, a metal sheet having a high reflectance or a metal thin film having a high reflectance is provided on a supporting substrate such as a film. A reflective sheet and a white film such as a foamed plastic film are preferably used.

By the way, in the example of FIG. 1, the light reflection layer 6b is made of a metal thin film attached to the supporting base material 6a, and it has an adhesive layer 6c having a refractive index lower than that of the optical path control layer 4 for the purpose of improving the light utilization efficiency. Are glued through. It is also possible to use the light source holder as described above by closely surrounding the lighting device arranged on the back side and / or the side surface on the viewing side with the light reflecting layer made of the above-mentioned reflecting sheet or the like. This method is advantageous in that the light from the lighting device can be highly concentrated on the side surface of the substrate and the brightness is improved.

The light reflecting layer may be a mirror surface, but from the viewpoint of preventing moire, a layer having a light diffusing function is preferable.
As described above, the light reflecting layer may be simply placed on the outside of the optical path control layer on the back side, or may be closely attached by an adhesive method or a vapor deposition method. When the light reflecting layer is closely arranged on the slope of the light emitting means as in the example of FIG. 1, there is an advantage that the leaking light can be almost completely prevented by the improvement of the reflection effect and the viewing angle characteristics and the brightness can be further improved.

The formation of the above-mentioned light diffusion type reflection layer is carried out by supporting a film having a fine uneven structure on the surface by an appropriate method such as a surface roughening method by sandblasting or matting, or a particle addition method. It can be carried out by a method of providing a light reflecting layer reflecting the fine concavo-convex structure on a substrate or the like. The formation of the light-reflecting layer can be performed by a method of attaching a metal to the surface of the supporting substrate or the like by an appropriate method such as a vapor deposition method such as a vacuum vapor deposition method, an ion plating method, a sputtering method, or a plating method. it can. The technique for forming such a light diffusion type reflection layer can be applied to the formation of the above-mentioned semi-transmissive reflection layer.

According to the liquid crystal display device of the present invention, in the illumination mode, most of the incident light from the incident side surface is transmitted rearward through the substrates on the back side and the viewing side and through the reflection according to the law of refraction to the rear side of the panel. The light incident on the optical path conversion slopes A1 and B1 of the optical path control layer is efficiently converted to the front and back directions of the panel with good vertical directivity, and other transmitted light is also totally reflected backward. Is further transmitted to the optical path changing slopes A1 and B1 at the rear side, and the optical path is efficiently changed in the front and back directions of the panel with good vertical directivity.

Next, the light whose light path has been changed by the above-mentioned light path changing slope reaches the semi-transmissive reflection layer, and the light transmitted through it (back side) and the light reflected by it (viewing side) enter the liquid crystal cell. As a result, display light is formed to achieve display with excellent brightness uniformity over the entire display surface of the panel. On the other hand, in the external light mode, external light incident from the viewing side reaches the semi-transmissive reflective layer, and the light reflected by it is used as display light in the liquid crystal cell,
A display with excellent brightness uniformity is achieved on the entire panel display surface.

When the light reflection layer is provided outside the optical path control layer on the back side, the light utilization efficiency is improved and the brightness is further improved as described above. Therefore, it is possible to form an external light / illumination type liquid crystal display device which is bright and easy to see and is excellent in display quality by efficiently utilizing external light or light from the lighting device.

In the present invention, the optical elements or parts such as the optical path control layer, the liquid crystal cell, the polarizing plate and the retardation plate forming the above-mentioned liquid crystal display device are wholly or partially laminated and fixed integrally. Alternatively, they may be arranged in an easily separable state. The fixed state is preferable from the standpoint of preventing the reduction of the contrast by suppressing the interface reflection. An appropriate transparent adhesive such as a pressure-sensitive adhesive can be used for the fixing and adhesion treatment, and the transparent adhesive layer can be made to contain the above-mentioned transparent particles or the like to form an adhesive layer having a diffusion function.

The above-mentioned optical elements or parts, especially those on the viewing side, are treated with an ultraviolet absorber such as a salicylate compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex salt compound. For example, it is possible to have an ultraviolet absorbing ability.

[0108]

EXAMPLES Reference Example 1 Magnesium fluoride was vacuum-deposited on a non-alkali glass plate having a thickness of 0.7 mm and a refractive index of 1.52 to form a low refractive index transparent layer having a thickness of 600 nm and a refractive index of 1.38. Then, a resin layer having a surface fine uneven structure was provided thereon. Next, aluminum is vacuum-deposited on it, and openings of 250 μm square are formed by etching so as to be evenly distributed with an opening ratio of 20% to provide a semi-transmissive reflective layer which also serves as an electrode, on which a polyvinyl alcohol solution is provided. Was spin-coated and the dried film was rubbed to obtain a backside substrate. On the other hand, a low-refractive-index transparent layer and an ITO transparent conductive layer are formed on an alkali-free glass plate similar to the above, the transparent electrode is etched and divided into two, and a rubbing treatment film is provided on the transparent electrode to form the viewing side substrate. Obtained.

Then, the back side substrate and the viewing side substrate are made to face each other so that the rubbing surfaces thereof are orthogonal to each other, a gap adjusting material is arranged, and the periphery is sealed with an epoxy resin, and then liquid crystal (ZLI manufactured by Merck & Co., Inc.) is used. -4792) was injected to form a TN liquid crystal cell, and polarizing plates with retardation plates were attached to both surfaces thereof to obtain a normally white liquid crystal panel. The panel size is 25 mm in width and 37 mm in length, and one side surface of the substrate on the back side and the viewing side in the length direction protrudes by about 3 mm from the substrate on the other side. Next, a cold cathode tube having a diameter of 1.8 mm is arranged so as to correspond to the center on the rear side of the opposite side of the panel and the protruding side of each substrate on the viewing side.
The film was surrounded by a silver vapor-deposited polyester film, and the ends of the film were adhered to the front and back ends of each substrate with double-sided adhesive tape to hold and fix the cold cathode tube.

Reference Example 2 A liquid crystal panel was obtained in the same manner as in Reference Example 1, except that the low-refractive-index transparent layers made of magnesium fluoride were not provided on the back and viewing side substrates.

Reference Example 3 Acrylic UV curable resin (Aronix UV-3701, manufactured by Toagosei Co., Ltd.) was applied to a mold which had been processed into a predetermined shape in advance.
After dropping and filling with a dropper, a polycarbonate (PC) film with a thickness of 60 μm was left standing and adhered with a rubber roller to remove excess resin and bubbles, and after being irradiated with ultraviolet rays with a metal halide lamp and cured. Then, the PC film is peeled off from the mold and cut into a predetermined size to obtain an optical path control layer (transparent sheet) having a refractive index of 1.51, and an acrylic film having a refractive index of 1.51 is provided on the surface having no optical path controlling layer. A system adhesive layer was attached.

The transparent sheet has a width of 22 mm and a length of 28 mm, and has prism-shaped concave portions whose ridge lines are inclined at an angle of 21 degrees over the width direction in a continuous manner at a pitch of 190 μm. The inclination angle is 42 degrees, the apex angle with the steep slope is 70 degrees (FIG. 3b), the projection width of the optical path conversion slope with respect to the reference plane is 7 to 12 μm, and the area of the flat portion (A3) is between the optical path conversion slope and the steep slope. It consists of 10 times or more of the total projected area with respect to the reference plane.

Reference Example 4 A transparent sheet with an adhesive layer was obtained according to Reference Example 3 using different molds. This transparent sheet has a light emitting means (FIG. 3b) having a length of 80 μm, which comprises an optical path changing slope having a slope of about 42 ° and a projection width of 10 μm on a reference plane and a steep slope having a slope of about 75 °. Is parallel to the incident side surface, and the light emitting means is arranged at a higher density as the distance from the incident side surface in the longitudinal direction increases (FIGS. 5 and 7), and the flat portion (A3). Area is 10 times or more the total projected area of the optical path conversion slope and the steep slope with respect to the reference plane.

Reference Example 5 A transparent sheet with an adhesive layer was obtained according to Reference Example 3 except that a mold whose surface was roughened by sandblasting was used.

Reference Example 6 A transparent sheet with an adhesive layer was obtained according to Reference Example 3 using different molds. This transparent sheet has a prism-shaped recess 190
It has continuously at a pitch of μm (FIG. 3b), the inclination angle of the optical path conversion slope is 30 degrees, the apex angle with the steep slope is 70 degrees, and the projection width of the optical path conversion slope with respect to the reference plane is 7 to 12 μm.
The flat part (A3) has an area of 10 times or more of the total projected area of the optical path conversion slope and the steep slope with respect to the reference plane.

Reference Example 7 Aluminum was vacuum-deposited on the light emitting means forming surface of the optical path control layer formed according to Reference Example 3 to obtain a transparent sheet provided with a light reflecting layer.

Reference Example 8 Aluminum was vacuum-deposited on the surface of a transparent plastic film to obtain a light reflecting sheet.

Reference Example 9 Aluminum was vacuum-deposited on the surface of a transparent plastic film, and an adhesive layer having a refractive index of 1.41 was formed thereon to obtain a light reflecting sheet.

Example 1 The transparent sheet of Reference Example 3 was adhered to the rear side and the viewing side of the liquid crystal panel of Reference Example 1 via the adhesive layer so that the optical path conversion slope faces the corresponding illuminating device, and the back side thereof. The light-reflecting sheet of Reference Example 8 was adhered to the side only through the adhesive layer to obtain a liquid crystal display device.

Example 2 A liquid crystal display device was obtained in the same manner as in Example 1 except that the light reflecting sheet of Reference Example 9 was used.

Example 3 A liquid crystal display device was obtained in the same manner as in Example 1 except that the transparent sheet of Reference Example 4 was used in place of the transparent sheet of Reference Example 3.

Example 4 A liquid crystal display device was prepared in the same manner as in Example 1 except that the transparent sheet on the back side was replaced with that of Reference Example 7 and the light reflecting sheet of Reference Example 8 was not used. Obtained.

Example 5 A liquid crystal display device was obtained in the same manner as in Example 1 except that the transparent sheet on the back side was replaced with that of Reference Example 3 instead of that of Reference Example 4.

Comparative Example 1 A liquid crystal display device was obtained in the same manner as in Example 1 except that the liquid crystal panel of Reference Example 2 was used instead of the liquid crystal panel of Reference Example 1.

Comparative Example 2 A liquid crystal display device was obtained in the same manner as in Example 2 except that the liquid crystal panel of Reference Example 2 was used instead of the liquid crystal panel of Reference Example 1.

Comparative Example 3 A liquid crystal display device was obtained in the same manner as in Example 1 except that the transparent sheet of Reference Example 5 was used instead of the transparent sheet of Reference Example 3.

Comparative Example 4 A liquid crystal display device was obtained in the same manner as in Example 1 except that the transparent sheet of Reference Example 6 was used instead of the transparent sheet of Reference Example 3.

Comparative Example 5 A liquid crystal display device was obtained in the same manner as in Example 1 except that the transparent sheet of Reference Example 3 was not placed on the viewing side.

Comparative Example 6 A liquid crystal display device was obtained in the same manner as in Example 1 except that the transparent sheet of Reference Example 3 was not arranged on the back side.

Evaluation Test Regarding the liquid crystal display devices obtained in Examples and Comparative Examples, the cold cathode tube was turned on in a dark room with no voltage applied to the liquid crystal cell, and the front luminance at the center position was measured by a luminance meter (manufactured by Topcon Corporation). , B
M7). Further, the display quality was evaluated when the display in the illumination mode was observed at the incident side surface end, the central part, and the opposite end. The evaluation was evaluated as ◯ when the light was bright and excellent in uniformity and satisfactorily emitted, and Δ when the brightness and the uniformity were slightly inferior, and x when dark and non-uniform.

The above results are shown in the following table. Front luminance display Quality (cd / m ² ) Incident side edge Central part Opposite edge Example 1 89 ○ ○ ○ Example 2 80 ○ ○ ○ Example 3 84 ○ ○ ○ Example 4 78 ○ ○ △ Example 5 82 ○ ○ △ Comparative Example 1 33 ○ × × Comparative Example 2 29 ○ × × Comparative Example 3 28 △ △ × Comparative Example 4 33 ○ △ × Comparative Example 5 52 ○ △ △ Comparative Example 6 48 ○ △ △

From the table, it can be seen that bright and uniform display is achieved in the illumination mode in the example, but very dark or non-uniform display is achieved in the comparative example. Further, in Examples 1 and 2 having the low refractive index transparent layer, the brightness and the uniformity thereof are high, but in Comparative Examples 1 and 2 not having the low refractive index transparent layer, the distance becomes farther from the incident side surface, and the light becomes sharper and the semi-transmission occurs. It was found that there was a large degree of non-uniformity in brightness, which was probably due to the effect of the reflective layer, and the display was extremely difficult to see.

Furthermore, even if the light reflecting layer of Example 4 is in close contact with the optical path control layer without a gap, or the type of the optical path control layer on the viewing side and the back side of Example 5 is different, bright and good illumination is obtained. It can be seen that Further, in Comparative Examples 5 and 6, it can be seen that the brightness is greatly reduced as compared with the Examples by disposing only one side of the optical path control layer. In addition, in Comparative Example 3 in which the optical path control layer was a rough surface and Comparative Example 4 in which the slope angle of the optical path control layer was small, light was not effectively emitted and it was dark.

On the other hand, when one of the cold cathode tubes was turned on and observed in the example, the angle characteristics of light emission were completely different between the viewing side and the back side. That is, in each case, the light was strongly emitted in the direction opposite to the illuminating device and was asymmetric. This also applies to the case where the optical path control layer is formed on either side as in Comparative Examples 5 and 6, and more light is emitted to the side opposite to the light source side with respect to the viewing angle. . On the other hand, in the embodiment, when both lights are turned on, each emits at an angle that complements each other,
It turns out that it can effectively illuminate a wider angle.

In both the examples and the comparative examples, the appearance was good in the external light mode, and no influence of the low refractive index transparent layer was observed. From the above, it is understood that the present invention realizes a thin and lightweight external light / illumination type liquid crystal display device capable of emitting light only by providing a light source device on an end face of a liquid crystal panel without using a light guide plate.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view of an embodiment.

FIG. 2 is a side view of a light emitting means in the optical path control layer.

FIG. 3 is a perspective explanatory view of still another embodiment.

FIG. 4 is an explanatory perspective view of still another embodiment.

FIG. 5 is an explanatory side view of an example of an optical path control layer.

FIG. 6 is a side view for explaining another example of the optical path control layer.

[Explanation of symbols]

1: Liquid crystal display panel 10, 20: Transparent substrate 11: Semi-transmissive reflective layer 21: Transparent electrode 12, 22: Alignment film 14, 24: transparent layer with low refractive index 15, 25: Polarizing plate 16, 26: Retardation plate 23: Color filter 30: Liquid crystal 4, 41: Optical path control layer A, B: Light emitting means A1, B1: Optical path conversion slope 5, 52: Lighting device 6: Light reflection layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/00 313 G09F 9/00 313 324 324 336 336B 336J 348 348C 9/30 310 9/30 310 330 330 330Z 349 349Z 9/35 9/35 // F21Y 103: 00 F21Y 103: 00 (72) Inventor Ryoji Kinoshita 1-2-1, Shimohozumi Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Inventor Ichiro Amino Nitto Denko Co., Ltd. 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture (72) Inventor Toshihiko Ariyoshi 1-2 1-2 Shimohozumi Shimohozumi, Ibaraki City, Osaka Prefecture F-Term (reference) 2H042 DA02 DA12 DA15 DA17 DA21 DB01 DB08 DC02 DE04 2H091 FA02Y FA08X FA08Z FA11X FA11Z FA15X FA15Y FA16Y FA41Y FD06 GA01 GA06 LA11 5C094 AA02 AA0 6 AA10 BA43 DA11 EA05 EA06 EB02 ED01 ED14 ED20 5G435 AA02 AA03 BB12 BB15 BB16 DD09 DD11 DD13 EE22 EE27 EE33 EE37 FF01 FF02 FF03 FF05 FF08

Claims (26)

[Claims] 1. A back side substrate having at least a transparent layer having a refractive index lower than that of the transparent substrate and a semi-transmissive reflective layer transmitting and reflecting light, and a transparent substrate having a refractive index lower than that of the transparent substrate. An illuminating device is provided on two or more side surfaces of a liquid crystal display panel including at least a liquid crystal cell in which a liquid crystal cell is sandwiched between a viewing side substrate having at least a layer and a transparent electrode, the electrode sides facing each other. And a plurality of optical path changing slopes having an inclination angle of 35 to 48 degrees with respect to the reference plane of the rear side substrate and the viewing side substrate, and having a refractive index higher than that of the nearest transparent layer having a low refractive index. A liquid crystal display panel characterized by being provided with a high optical path control layer, and wherein the lighting device is arranged at least on the side surfaces of the back side and the viewing side of the respective substrates, and on different side surfaces of the liquid crystal display panel. Indicating device. 2. The liquid crystal display device according to claim 1, wherein the transparent layer having a low refractive index is located between the transparent substrate and the semi-transmissive reflective layer or the transparent electrode, and the semi-transmissive reflective layer also serves as an electrode. 3. The semi-transmissive reflection layer having a concave-convex light-scattering surface via a transparent layer having a low refractive index on a transparent substrate forming the back-side substrate, and the semi-transmissive reflection thereof. A liquid crystal display device having a transparent electrode on a layer through a transparent insulating layer having a smooth surface. 4. The liquid crystal display device according to claim 1, further comprising a light reflection layer outside the optical path control layer arranged on the rear substrate side. 5. The liquid crystal display device according to claim 4, wherein the light reflection layer has at least a metal thin film. 6. The liquid crystal display device according to claim 4, wherein the light reflection layer is in close contact with the optical path control layer without a gap. 7. The liquid crystal display device according to claim 4, wherein an air layer is interposed between the light reflection layer and the optical path control layer. 8. The liquid crystal display according to claim 4, wherein the light reflection layer is made of a film, and the light reflection layer is adhered to the light path control layer by an adhesive means having a refractive index smaller than that of the light path control layer. apparatus. 9. The liquid crystal display device according to claim 8, wherein the light reflection layer comprises at least a base film provided with a metal thin film. 10. The liquid crystal display device according to claim 1, wherein a difference in refractive index between the transparent substrate forming the rear side or the viewing side substrate and the nearest transparent layer having a low refractive index is 0.05 or more. 11. The liquid crystal display device according to claim 1, wherein the transparent substrate forming the substrate on the back side or the viewing side of the liquid crystal cell is made of an optically isotropic material. 12. The liquid crystal display device according to claim 1, wherein the liquid crystal display panel has polarizing plates on one side or both sides of the liquid crystal cell. 13. The liquid crystal display device according to claim 12, wherein the liquid crystal display panel has one or more layers of retardation film between the liquid crystal cell and the polarizing plate. 14. The liquid crystal display device according to claim 1, wherein the optical path control layer has a plurality of prism-shaped concavities and convexities provided with an optical path conversion inclined surface facing the lighting device. 15. The liquid crystal display device according to claim 14, wherein the prismatic irregularities of the optical path control layer are concave portions having a triangular cross section. 16. The liquid crystal display device according to claim 15, wherein the prismatic concave portion is a continuous groove extending from one end to the other end of the optical path control layer in a ridge direction parallel or inclined to a side surface of the liquid crystal display panel on which the illumination device is arranged. 17. The liquid crystal display device according to claim 14, wherein the prismatic concave portion is a discontinuous groove, and the length of the groove is 5 times or more the depth. 18. The liquid crystal display device according to claim 17, wherein the lengthwise direction of the discontinuous groove of the prismatic concave portion is parallel or inclined to the side surface of the liquid crystal display panel on which the illumination device is arranged. 19. The lighting device according to claim 14, wherein the illuminating device is arranged on two opposite side faces of at least one of the rear side and the viewing side substrate, and the optical path control is provided on the substrate on which the illuminating device is arranged on the two side faces. A liquid crystal display device, wherein the prismatic irregularities of the layer are concave or convex portions having a triangular cross section or a quadrangular cross section having two optical path conversion slopes facing the illuminating device. 20. The liquid crystal display device according to claim 1, wherein the inclination angle of the optical path conversion slope in the optical path control layer is 38 to 45 degrees. 21. The optical path control layer according to claim 1, comprising a transparent sheet, which is adhered to the outer surface side of the liquid crystal display panel via an adhesive layer having a higher refractive index than the nearest transparent layer having a low refractive index. Liquid crystal display device. 22. The liquid crystal display device according to claim 21, wherein the adhesive layer is an adhesive layer. 23. The liquid crystal display device according to claim 1, wherein the optical path control layer and the adhesive layer have a refractive index higher than that of the nearest transparent layer having a low refractive index by 0.05 or more. 24. The lighting device according to any one of claims 1 to 23, wherein the lighting device is surrounded by a light-reflecting light source holder, and is bonded to an end portion of an upper surface and a lower surface of a viewing-side substrate or a rear-side substrate through an end portion of the light source holder. Liquid crystal display device which is arranged and held on the side surface of the viewing side substrate or the back side substrate by the above method. 25. The liquid crystal display device according to any one of claims 1 to 24, wherein the lighting device is arranged at least on a side surface of each of the back side and the viewing side of the substrate and on an opposite side surface of the liquid crystal display panel. 26. The liquid crystal display device according to claim 1, wherein a circuit for driving a liquid crystal is formed between the transparent layer having a low refractive index and the semi-transmissive reflective layer on the rear substrate.