JP2008262224A - Reflective liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a reflective liquid crystal display for both external light and illumination which is easy to manufacture thin and lightweight, and has superior display quality. <P>SOLUTION: The reflective liquid crystal display includes a reflective liquid crystal display panel (1) comprising a liquid cell, in which a viewing side substrate (21) having a transparent layer (22) with a lower refractive index than that of a transparent substrate, and having a transparent electrode (24) and a back-side substrate (43) having an electrode (42) are arranged on the transparent substrate so that the electrode sides are opposed to each other and a liquid crystal (31) held between the electrodes; and at least a reflecting layer (42) on the back side substrate side. The reflective liquid crystal display further includes a lighting device on one or more sides of the reflective liquid crystal display panel (1); and an optical path control layer (11), having a repeated structure of a light path conversion slanted face (A1), having 35-48° angle with respect to the reference plane of the viewing side substrate, provided outside the viewing-side substrate and having a refractive index higher than that of the transparent layer. While the side surface incident light is transmitted backward, the transmitted light is efficiently subjected to optical path conversion to the panel viewing direction via the optical path control layer and the reflecting layer and is used for the liquid crystal display. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reflection type liquid crystal display device that can be easily reduced in thickness and weight, has excellent display quality, and is used for both external light and illumination.

In order to reduce the thickness and weight of a reflection type liquid crystal display device for the purpose of reducing the size and weight of a portable personal computer, a cellular phone, etc., a front light with a conventional sidelight type light guide plate is provided (Japanese Patent Laid-Open No. 11-1990). 250715), making it thin and light is difficult. Incidentally, the side light type light guide plate has a thickness of about 2 mm or more due to the necessity of light transmission, and when an optical member such as a light diffusion plate is disposed on the side light type light guide plate, the thickness is usually 3 mm or more.
JP-A-11-250715

  It is an object of the present invention to develop an external light / illumination type reflection type liquid crystal display device that is easy to reduce the thickness and weight and has excellent display quality.

  In the present invention, a liquid crystal is sandwiched between a transparent substrate having a lower refractive index than that substrate and a substrate on the viewing side having a transparent electrode, and a substrate on the back side having the electrodes facing each other. A reflective liquid crystal display panel having at least a reflective layer on the side of the liquid crystal cell and the back side substrate, and having a lighting device on one or more side surfaces, and a reference plane of the substrate outside the viewing side substrate A reflection type liquid crystal display device having a repeating structure of an optical path conversion slope with an inclination angle of 35 to 48 degrees with respect to the optical path control layer having a refractive index higher than that of the low refractive index transparent layer. It is to provide.

  According to the present invention, the incident light from the lighting device disposed on the side surface of the panel using the liquid crystal cell substrate is efficiently transmitted in the direction of the opposite side surface, while the optical path control layer disposed on the viewing side and the rear surface side. The light transmitted through the reflective layer can be used for liquid crystal display by efficiently changing the optical path in the viewing direction of the liquid crystal display panel, and the front light mechanism can be formed with the light path control layer having excellent lateral arrangement and thinness of the lighting device, and An external light / illumination type reflective liquid crystal display device which can display even in the external light mode, is excellent in thinness and light weight, is bright and excellent in display quality can be obtained.

  This is because a transparent layer having a low refractive index and a slope reflection type optical path control layer provided on the viewing side substrate are used. In other words, the confinement effect due to total reflection based on a transparent layer with a low refractive index enables efficient transmission of incident light from the side of the panel in the direction of the opposite side, improving brightness uniformity across the entire screen and providing good display quality. Achieved. Without a transparent layer having a low refractive index, the rearward transmission efficiency is poor, and the screen becomes darker and harder to see as the distance from the illumination device increases. On the other hand, it is possible to change the optical path with good directivity by reflecting incident light or its transmitted light from the side surface through the optical path changing slope, and in the scattering reflection method through the rough surface as in JP-A-5-158033, the above-mentioned effect is obtained. Is difficult to achieve.

  That is, the above publication teaches a reflection type liquid crystal display device in which illumination light is incident from the side surface of a liquid crystal display panel and totally reflected by a cell substrate on the viewing side, and the reflected light is scattered by a rough surface type reflection plate and used for display. However, in that case, the light that can be used for display is light that is out of the total reflection condition due to scattering and is emitted from the panel. Generally, since the scattered light has a normal distribution with a peak in the regular reflection direction, the display light is The light that is difficult to effectively use for the display tilted larger than the front (vertical) direction is dark in the front direction. Increasing the scattering by the rough reflector is disadvantageous for display by reducing the amount of light in the front direction in the external light mode. Therefore, in such a rough surface scattering reflection method, it is necessary to adjust the scattering intensity so that it is balanced in both the external light and illumination modes. However, since the balance relationship is contradictory, it is possible to make the scattering intensity advantageous to both. Have difficulty.

  On the other hand, the slant reflection type optical path control layer according to the present invention mainly uses light in the regular reflection direction showing a peak, and controls the optical path of the reflected light. The directivity in the front direction can be easily provided, and a bright illumination mode can be achieved. Further, even in the external light mode, since a flat portion other than the inclined surface of the optical path control layer can be used, it is possible to easily balance the state advantageous to both the illumination and external light modes.

  In the reflection type liquid crystal display device according to the present invention, a transparent substrate having a lower refractive index than the substrate and a viewing side substrate having a transparent electrode and a back side substrate having an electrode are arranged with their electrode sides facing each other. A liquid crystal cell having a liquid crystal sandwiched between them and a reflective liquid crystal display panel having at least a reflective layer on the back substrate side and having an illuminating device on one or more side surfaces; And an optical path control layer having a repetitive structure of an optical path changing slope with an inclination angle of 35 to 48 degrees with respect to a reference plane of the substrate, and an optical path control layer having a refractive index higher than that of the low refractive index transparent layer.

  Examples of the reflection type liquid crystal display device described above are shown in FIGS. 1, 2, and 4 to 6. 1, 2, 3, 4, and 5 are liquid crystal display panels, 11 is an optical path control layer, A1 is an optical path conversion slope, 21 is a transparent substrate (viewing side substrate), 22 is a low refractive index transparent layer, and 24 is a transparent electrode. 43 and 45 are back side substrates, 42 and 44 are electrodes thereof, 31 is a liquid crystal, 16 and 42 are reflection layers, and 51 and 53 are illumination devices. Therefore, the electrode 42 also serves as a reflective layer. In addition, 12 and 15 are polarizing plates, 13 and 14 are retardation plates, 23 is a color filter, and 25 and 41 are alignment films.

  As a liquid crystal display panel, as shown in the figure, a transparent substrate (21) has a transparent layer 22 having a refractive index lower than that of the substrate and a viewing side substrate 21 having a transparent electrode 24, a back side substrate 43 having electrodes 42 and 44, 45 and a liquid crystal cell sandwiching the liquid crystal 31 between the electrodes 24, 42, 44 facing each other, and at least a reflective layer 42, 16 on the back substrate 43, 45 side. Thus, it is necessary to use an appropriate reflective type that emits incident light from the viewing side on which the optical path control layer 11 is disposed as display light through reflection inversion by the reflective layers 42 and 16 and control by the liquid crystal 31 or the like. There is no particular limitation on the type. In the figure, reference numeral 32 denotes a sealing material for enclosing the liquid crystal 31 between the substrates 21, 43 and 45.

  Incidentally, specific examples of the liquid crystal cell described above include twisted and non-twisted types such as TN liquid crystal cell, STN liquid crystal cell, vertical alignment cell, HAN cell, and OCB cell, guest host type, and ferroelectric based on the alignment mode of the liquid crystal. For example, a liquid crystal system and a liquid crystal display utilizing light diffusion, and the liquid crystal drive system may be an appropriate one such as an active matrix system or a passive matrix system. The liquid crystal is typically driven through transparent electrodes 24 and 44 or reflective electrodes 42 provided inside a pair of cell substrates 21 and 42 as shown in the figure.

  A transparent substrate is used for the viewing side substrate in order to allow transmission of display light. The transparent substrate can be formed of an appropriate material such as glass or resin, and in particular, is preferably made of an optically isotropic material from the viewpoint of suppressing birefringence as much as possible and reducing optical loss. . In addition, from the viewpoint of improvement in luminance and display quality, those having excellent colorless transparency such as an alkali-free glass plate with respect to a blue glass plate are preferable, and a resin substrate is more preferable in terms of lightness and the like.

  The low refractive index transparent layer provided on the viewing side substrate is provided as a layer having a lower refractive index than the transparent substrate forming the viewing side substrate, so that the incident light from the illumination device 51 is incident as indicated by the broken line arrow α2 in FIG. When the light is transmitted through the viewing side substrate 21, the transmitted light is totally reflected through the difference in refractive index between the substrate 21 and the transparent layer 22 to efficiently confine the light within the viewing side substrate, thereby confining the transmitted light. Aims to improve the uniformity of the brightness of the entire display screen by efficiently transmitting backward and supplying the transmitted light evenly to the light path change slope of the light path control layer at a position far from the illuminating device and through the light path change by reflection. And

  In the transparent layer having a low refractive index, the transmission light is incident on the liquid crystal layer and is subjected to birefringence or scattering, whereby the transmission state is partially changed to reduce or make the transmission light nonuniform. It is also intended to prevent the display from becoming darker and to prevent the display in the vicinity of the illumination device from becoming ghosted in the rear to deteriorate the display quality. It is another object of the present invention to prevent a decrease in transmitted light by preventing sudden absorption of transmitted light when a color filter or the like is disposed. In the case where incident light from an illuminating device is transmitted through the liquid crystal layer, such as a reflection type liquid crystal display device taught in Japanese Patent Laid-Open No. 5-158033, the transmitted light is scattered by the liquid crystal layer, resulting in an uneven transmission state. The display image tends to be difficult to see due to uneven illumination and ghosting.

  The low refractive index transparent layer has a lower refractive index than the transparent substrate forming the viewing side substrate, such as a vacuum deposition method or a spin coating method using an appropriate material such as an inorganic or organic low refractive index dielectric. There are no particular limitations on the material and the formation method. The difference in refractive index between the transparent layer and the transparent substrate is more advantageous from the viewpoint of the transmission efficiency to the rear due to the total reflection described above, and is more preferably 0.05 or more, especially 0.1 to 0.5. preferable. Such a difference in refractive index hardly affects the display quality in the external light mode. Incidentally, when the difference in refractive index is 0.1, the reflectance of external light at the interface is 0.1% or less, and the reduction 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 determined as appropriate, but it is preferably located between the transparent substrate and the transparent electrode from the viewpoints of the confinement effect of the transmission light and the prevention of intrusion into the liquid crystal layer. Further, when a color filter is disposed between the transparent substrate and the transparent electrode, it is preferable that the color filter is positioned closer to the substrate 21 than the color filter 23 as shown in the figure from the viewpoint of preventing transmission light from being absorbed by the color filter. . Therefore, the transparent layer 22 having a low refractive index is usually provided directly on the viewing side substrate 21. In that case, the smoother the surface on which the transparent layer is provided on the substrate, the smoother the transparent layer is, the more advantageous for preventing scattering of transmitted light, and more preferable for preventing the influence on display light.

  If the thickness of the transparent layer having a low refractive index is too thin, it may be more advantageous to maintain the total reflection effect than the above-described confinement effect due to the phenomenon of wave oozing. The thickness can be appropriately determined from the point of total reflection effect and the like. Generally, from the point 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, the refractive index × layer The thickness is preferably ¼ wavelength (95 nm) or more, especially ½ wavelength (190 nm) or more, particularly 1 wavelength (380 nm) or more, more preferably 600 nm or more, based on the optical path length calculated by the thickness. It is preferable that it is the thickness of this.

  On the other hand, for the back side substrate, for example, when the electrode serving as the reflective layer is provided in the liquid crystal cell as in the example of FIG. 1, it is not necessary to be light transmissive, so that an arbitrary substrate 43 can be used. It may be. In that case, when the liquid crystal cell is a type that realizes display by light scattering or transmission / absorption difference, a black substrate can be preferably used from the point of black display. On the other hand, as shown in the example of FIG. 2, the transparent substrate 45 is used when it is necessary to have the reflective layer 16 outside the cell and to make the back substrate transparent. About the transparent substrate, it can follow the above-mentioned visual recognition side board | substrate.

  The thicknesses of the viewing side substrate and the back side substrate are not particularly limited and can be appropriately determined according to the sealing strength of the liquid crystal. In general, the thickness is 10 μm to 5 mm, especially 50 μm to 2 mm, especially 100 μm to 1 mm, in view of the balance between light transmission efficiency and thin and light weight. In particular, when the viewing-side substrate is used as a transmission substrate for incident light from the illumination device as described above, it is advantageous that the cross-sectional area is larger than the incident efficiency, transmission efficiency, and the like. On the other hand, it is more advantageous that the back side substrate is thinner than the point of reducing the thickness and weight. Therefore, the thickness of the visual recognition side board | substrate and the back side board | substrate may be the same, and may differ. The substrate may be the same thickness, and in particular, the viewing side substrate is partially thick like a wedge-shaped cross section for the purpose of improving the incident efficiency of the transmitted light to the optical path conversion slope by the inclined arrangement of the optical path control layer. It may be different.

  The viewing-side substrate and the back-side substrate may have the same or different planar dimensions. When the viewing side substrate is used as a transmission substrate for incident light from the illuminating device, at least the side surface on the side where the illuminating devices 51 and 53 are arranged, as shown in the figure, is more visible than the side surface formed by the back side substrates 43 and 45. It is preferable that the side surface formed by the substrate 21 protrudes from the viewpoint of incident efficiency and the like when the lighting device is disposed on the protruding side surface.

  The transparent electrodes 24, 44 provided on the viewing side substrate 21, the back side substrate 45, etc. can be formed of an appropriate material according to the prior art such as ITO. On the other hand, the reflective layer electrode 42 provided on the back-side substrate 43 or the like can be formed of, for example, an appropriate reflective metal or the like, and is preferably formed as a thin film of a metal having high reflectivity and good electrical conductivity such as aluminum. . In this case, when the viewing side substrate is a transmission substrate for incident light from the illumination device, the transmission light in the substrate is difficult to reach the reflection layer until it is reflected by the light path conversion slope of the optical path control layer. Therefore, a scattering reflective layer can be obtained. The same applies when a reflective layer is provided outside the cell as in the example of FIG.

  As described above, the reflective layer provided on the inner side or the outer side of the back side substrate in the liquid crystal cell reflects the incident transmission light from the illumination device by the optical path conversion slope A1 of the optical path control layer 11 as shown by the broken line arrow in FIG. The optical path is changed to the side substrate side, and the light is reflected and inverted to obtain the display light α1 in the illumination mode, and the incident external light through the optical path control layer 11 is reflected and inverted to obtain the display light β in the external light mode. Accordingly, an external light / illumination type reflection type liquid crystal display device is formed.

  The reflective layer, particularly the reflective layer provided outside the cell, can be formed of an appropriate material such as a white sheet according to the prior art. In particular, for example, a coating layer in which a powder of a highly reflective metal such as aluminum, silver, gold, copper, or chromium or an alloy thereof is contained in a binder resin, and the metal or dielectric multilayer film is vacuum-deposited. A layer formed by an appropriate thin film forming method such as a sputtering method, a reflective sheet in which the coating layer or the attached layer is supported by a substrate made of a film, a reflective layer having a high reflectivity made of a metal foil, etc. preferable.

  The reflective layer to be formed may exhibit a light scattering function as described above. It is possible to improve the directivity in the front direction by diffusing the reflected light on the scattering reflection surface, and to improve the visibility by preventing the generation of Newton rings due to adhesion when roughening the surface. Can do. Therefore, the reflective layer provided outside the cell may be in a state where it is simply placed on top of each other, or may be in a state of being in close contact with an adhesive method or a vapor deposition method.

  The light-scattering type reflective layer is formed on a film substrate having a surface with a fine concavo-convex structure by an appropriate method such as a surface roughening method such as sand blasting or matting, or a particle addition method. This can be done by a method of providing a reflective layer reflecting the above. The reflective layer of the fine concavo-convex structure reflecting the fine concavo-convex structure on the surface is formed by, for example, applying a metal film to the film substrate by an appropriate method such as a vacuum deposition method, an ion plating method, a sputtering method, or a deposition method. It can be performed by a method of attaching to the surface of the like.

  When forming the liquid crystal cell, one or two or more appropriate functional layers such as an alignment film composed of a rubbing treatment film for aligning liquid crystals and a color filter for color display can be provided as necessary. . As shown in the figure, the alignment films 25 and 41 are usually formed on the electrodes 24, 42 and 44, and the color filter 23 is usually provided between the substrate and the transparent electrode on one of the cell substrates 21 and 45. . In the illustrated example, a color filter 23 is provided on the viewing side substrate 21.

  The liquid crystal display panel may be one in which one or two or more appropriate optical layers such as polarizing plates 12 and 15, retardation plates 13 and 14, and a light diffusion layer are added to a liquid crystal cell as shown in the figure. . The purpose of the polarizing plate is to achieve display using linearly polarized light, and the purpose of the retardation plate is to improve display quality by compensating for the phase difference due to the birefringence of the liquid crystal. The light diffusion layer also 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 controls the optical path by diffusing the transmitted light in the liquid crystal display panel The purpose is to increase the amount of light incident on the layer.

  As the polarizing plate, any suitable one can be used and there is no particular limitation. Higher hydrophilicity such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, ethylene / vinyl acetate copolymer partially saponified film, etc. A highly polarizing film such as an absorbing polarizing film formed by adsorbing and stretching a dichroic substance such as iodine or a dichroic dye on a molecular film or a transparent protective layer provided on one or both sides thereof. It can be preferably used.

  For the formation of the transparent protective layer, those excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, etc. are preferably used. Examples thereof include acetate resins, polyester resins, polyethersulfone resins, Polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins, polyether resins, polyvinyl chloride, polymers such as styrene resins, norbornene resins, acrylic resins, urethane resins, acrylic urethane resins And epoxy- and silicone-based thermosetting or ultraviolet curable resins. The transparent protective layer can be applied by a bonding method of a film or a coating method of a polymer liquid or the like. The polarizing plate can be provided on both sides of the liquid crystal cell as shown in the figure, or can be provided only on one side of the liquid crystal cell.

  On the other hand, as a retardation plate, for example, a birefringent film obtained by stretching a film made of an appropriate polymer such as those exemplified in the transparent protective layer by an appropriate method such as uniaxial or biaxial, nematic or disco An appropriate film such as an alignment film of an appropriate liquid crystal polymer such as a tick system or an alignment layer of which an alignment layer is supported by a transparent substrate can be used. Those having a controlled refractive index may be used. Compensation phase difference plates 13 and 14 are usually arranged between the viewing side and / or back side polarizing plates 12 and 15 and the liquid crystal cell as required, as shown in the figure. An appropriate one can be used according to the above. The retardation plate can be used by superposing two or more layers for the purpose of controlling optical characteristics such as retardation.

  The illuminating device disposed on the side surface of the liquid crystal display panel is intended to make light used as illumination light of the reflective liquid crystal display device incident from the side surface of the liquid crystal display panel. Thus, the reflective liquid crystal display device can be reduced in thickness and weight in combination with the optical path control layer disposed on the viewing side of the panel. From the viewpoint of preventing the incident light from the illuminating device from entering the liquid crystal layer, the preferred arrangement method of the illuminating device is that the viewing side substrate protrudes from the side surface of the viewing side substrate, particularly the side surface formed by the back side substrate as described above. It is a method of arranging with respect to the side surface.

  An appropriate lighting device can be used. For example, a linear light source such as a (cold, hot) cathode tube, a point light source such as a light emitting diode, an array body in which the light source is arranged in a linear or planar shape, or a point An illuminating device that combines a light source and a linear light guide plate to convert incident light from a point light source into a linear light source via the linear light guide plate can be preferably used. As in the example of FIGS. 1 and 2, the illumination devices 51 and 53 can be arranged on one or more side surfaces of the liquid crystal display panel. When the lighting device is arranged on two or more side surfaces, the plurality of side surfaces may be a combination of opposing side surfaces as in the example of FIG. 2 or a combination of side surfaces that intersect vertically and horizontally. It may be a combination of three or more side surfaces used in combination.

  The illuminating device enables visual recognition in the illumination mode by lighting thereof, and does not need to be lit when visually confirming in the external light mode, and thus can be switched on / off. As the switching method, any method can be adopted, and any of the conventional methods can be adopted. Note that the illumination device may be of a different color light emission type capable of switching the emission color, or may be capable of emitting different color light through different types of illumination devices.

  As shown in the figure, for the lighting devices 51 and 53, a combination body in which appropriate auxiliary means such as light source holders 52 and 54 surrounding the light devices 51 and 53 are arranged to guide the diverging light to the side surface of the liquid crystal display panel as necessary. You can also As the light source holder, for example, a suitable reflection sheet that reflects light at least on the side of the illumination device can be used, such as a resin sheet provided with a highly reflective metal thin film, a white sheet, or a metal foil. The light source holder can also be used as a holding means that also serves as an enclosure for the illumination device by bonding its end to the cell substrate of the liquid crystal display panel, in particular, to the upper and lower ends of the viewing side substrate.

  As illustrated in FIG. 1, the optical path control layer converts the incident light from the illuminating device 51 arranged on the side surface of the liquid crystal display panel or its transmitted light through the optical path converting slope A1 toward the back side substrate of the panel, and reflects it. It is intended to be used as illumination light (display light) through reflection reversal by the layer 42, and is disposed outside the viewing side substrate 21 of the liquid crystal display panel, generally on the viewing side.

  For the above purpose, the optical path control layer 11 reflects the incident light from the illuminating devices 51 and 53 and changes the optical path in a predetermined direction as in the examples of FIGS. An optical path conversion slope A1 with an inclination angle of 35 to 48 degrees with respect to is assumed. The optical path control layer has a repeating structure of the optical path conversion slope for the purpose of thinning. Furthermore, the optical path control layer is formed as a layer having a higher refractive index than the low refractive index transparent layer provided on the viewing side substrate. If the refractive index of the optical path control layer is lower than that of the transparent layer, the incident light from the illuminating device or the transmitted light is easily confined in the viewing side substrate, and the incidence to the optical path control layer is hindered and used as display light. It becomes difficult.

  The optical path control layer can be formed in an appropriate form except that the optical path control layer has a repeated structure of the predetermined optical path conversion slope. Rather than having display light with excellent directivity in the front direction through optical path conversion or the like, the optical path conversion means A has a repeating structure including an optical path conversion slope A1 facing the side surface on which the illumination device is arranged, that is, the incident side surface. An optical path control layer, particularly an optical path control layer having a repeating structure of the optical path conversion means A having an optical path conversion slope A1 made of prismatic irregularities is preferable.

  3A to 3E show examples of the optical path changing means having the above-described optical path changing slopes or prism-like irregularities. In (a) to (c), the optical path changing means A has a substantially triangular cross section, and in (d) and (e), it has a substantially square cross section. Further, (a) has two optical path conversion slopes A1 of isosceles triangles, and (b) has optical path conversion means A having a steep slope A2 having an inclination angle with respect to the optical path conversion slope A1 and the reference plane larger than the slope A1. Consists of things. In (c), the optical path conversion means A in units of the optical path conversion slope A1 and the gentle slope A2 having a small inclination angle with respect to the reference plane is formed on the entire surface of one side of the optical path control layer as an adjacent continuous state repeating structure. In (d), it has optical path changing means A consisting of convex parts (protrusions), and in (e) it has optical path changing means A consisting of concave parts (grooves).

  Therefore, as in the above-described example, the optical path changing means can be formed on a convex portion or a concave portion having an equilateral surface or an inclined surface having the same inclination angle, or an optical path changing inclined surface and a steep slope or a gentle inclined surface or an inclined surface having different inclination angles. It can also be formed in a convex part or a concave part, and the slope form can be appropriately determined by the number and position of incident side surfaces. From the viewpoint of maintaining the slope function by improving the scratch resistance, it is advantageous that the slope or the like is not easily damaged because it is formed as a light path changing means including a concave portion rather than a convex portion.

  A more preferable optical path control layer, such as the above-mentioned characteristics such as directivity in the front direction, has an optical path conversion slope A1 having an inclination angle of 35 to 48 degrees with respect to the reference plane facing the incident side as shown in the figure. Is. Accordingly, when the lighting device is disposed on two or more side surfaces of the liquid crystal display panel and has two or more incident side surfaces, an optical path control layer having an optical path conversion slope A1 corresponding to the number and position is preferably used. .

  Incidentally, in the case where the illuminating devices 51 and 53 are arranged on the two opposing side surfaces of the liquid crystal display panel as in the example of FIG. 2, the two surfaces by the optical path changing means A having a substantially isosceles triangle cross section as shown in FIG. Optical path control having optical path conversion slope A1 and two optical path conversion slopes A1 by optical path conversion means A having a substantially trapezoidal cross section as shown in FIGS. 3D and 3E in a state where the ridge line is in a direction along the incident side surface. Layer 11 is preferably used. Further, when the illuminating device is arranged on two side surfaces adjacent to each other in the vertical and horizontal directions of the liquid crystal display panel, an optical path control layer having an optical path conversion slope A1 in a state in which the ridge line extends in both the vertical and horizontal directions corresponding to the side surfaces is preferably used. Furthermore, when arrange | positioning an illuminating device on three or more side surfaces including opposing and vertical and horizontal, the optical path control layer which has optical path conversion slope A1 which consists of said combination is used preferably.

  The optical path changing slope A1 reflects the incident light from the incident side face through the lighting device or the transmitted light, and reflects the light incident on the face A1, changes the optical path, and supplies it to the back side of the liquid crystal display panel. do. In this case, by changing the inclination angle of the optical path conversion slope A1 with respect to the reference plane to 35 to 48 degrees, the side incident light or its transmitted light is optically converted with good perpendicularity to the reference plane as illustrated by the broken line arrow in FIG. Thus, it is possible to efficiently obtain display light having excellent directivity toward the front. If the tilt angle is less than 35 degrees, the optical path of the reflected light through the reflective layer is greatly deviated from the front direction, making it difficult to effectively use for display, and the brightness in the front direction is poor. As a result, the leakage light from the optical path changing slope increases and the light utilization efficiency of side incident light becomes poor.

  The preferable inclination angle of the light path conversion inclined surface A1 from the viewpoint of the optical path conversion excellent in directivity to the front and the suppression of leaking light is the total reflection condition based on the refraction by Snell's law of light transmitted through the liquid crystal display panel. Considering 38 to 45 degrees, and especially 40 to 44 degrees. Incidentally, the general total reflection condition of the glass plate is 42 degrees. Therefore, in this case, the incident light on the side surface is incident on the light path converting slope while being transmitted in a state of being gathered in a range of ± 42 degrees.

  The optical path changing means A having the optical path changing slope A1 is formed as a repetitive structure as illustrated in FIGS. 4, 5, and 6 for the purpose of reducing the thickness of the optical path control layer as described above. In view of the fact that incident light from the incident side is reflected rearward and efficiently transmitted to the opposite side to emit light as uniformly as possible on the entire surface of the liquid crystal display as shown in FIG. It is preferable to have a structure including a gentle slope A2 of 10 degrees or less, especially 5 degrees or less, particularly 3 degrees or less, or a flat surface A3 having an inclination angle of approximately 0 degrees. Therefore, the optical path changing means A including the steep slope A2 illustrated in FIG. 3B has a structure that can widen the flat surface A3 by setting the angle of the steep slope to 35 degrees or more, especially 50 degrees or more, particularly 60 degrees or more. It is preferable.

  Further, the gentle slope A2 or flat surface A3 includes the display light α1 in the illumination mode as shown in the example of FIG. 1, and the reflected display light β through the incident portion of the external light in the external light mode and the reflection layer 42 of the incident light. Thus, a reflection type liquid crystal display device for both external light and illumination is achieved. In this case, in particular, when the optical path changing means A is composed of adjacent repeating structures with the slopes A1 and A2 as shown in FIG. 3B, the angle difference of the inclination angle of the gentle slope A2 with respect to the reference plane is set to 5 degrees for the entire optical path control layer. Within 3 degrees, especially within 3 degrees, and the difference in inclination angle between the nearest gentle slopes is preferably within 1 degree, within 0.3 degrees, especially within 0.1 degrees. The purpose of this is to prevent the optimum viewing direction of the reflective liquid crystal display device, especially, the optimum viewing direction in the vicinity of the front direction from changing greatly by the transmission of the gentle slope A2, and not to change greatly between the nearest gentle slopes. And From the viewpoint of obtaining a bright display in the external light mode, it is preferable that the projected area of the gentle slope A2 with respect to the reference plane is 5 times or more, especially 10 times or more, especially 15 times or more that of the optical path conversion slope A1. This is intended to improve the incident efficiency of external light and the transmission efficiency of reflected display light through the reflective layer.

  As shown in FIGS. 4 to 6, the optical path changing means A is provided so that its ridge line is parallel or inclined along the incident side surface of the liquid crystal display panel on which the illumination device 51 is arranged. 4 and 5 may be formed continuously from one end to the other end of the optical path control layer, or may be formed intermittently discontinuously as shown in FIG. In the case of discontinuous formation, the length in the direction along the incident side surface of the irregularities formed by the grooves or protrusions is set to be 5 times or more of the depth or height in terms of the incident efficiency of transmission light, the optical path conversion efficiency, and the like. The length is preferably 500 μm or less, more preferably 10 to 480 μm, especially 50 to 450 μm from the viewpoint of uniform light emission on the panel display surface.

  There is no particular limitation on the cross-sectional shape of the optical path conversion means A and the repetitive pitch of the optical path conversion slope A1 through the optical path conversion means A, and the optical path conversion slope A1 becomes a luminance determining factor in the illumination mode. It can be determined appropriately according to the uniformity of light emission on the panel display surface, and the optical path conversion light quantity can be controlled by the distribution density. Accordingly, the inclination angle of the slopes A1 and A2 may be a constant shape over the entire surface of the optical path control layer, or the light emission on the panel display surface is made uniform by dealing with attenuation of transmitted light due to absorption loss and previous optical path conversion. In order to achieve the above, the optical path changing means A may be enlarged as the distance from the incident side surface increases as illustrated in FIG.

  Further, as shown in FIG. 7, the optical path changing means A having a constant pitch can be used, or as shown in FIG. 8, as the distance from the incident side surface is increased, the pitch is gradually narrowed to increase the distribution density of the optical path changing means A. It is also possible to make light emission uniform on the panel display surface at a random pitch. In addition, in the case where the optical path changing means A has irregularities composed of discontinuous grooves or protrusions, the irregularities in size and shape, distribution density, ridge line direction, etc. are irregular or irregular or regular. Or uniform unevenness can be arranged at random to make the light emission on the panel display surface uniform. Therefore, as in the example described above, uniform light emission on the panel display surface can be achieved by applying an appropriate method to the optical path conversion means A. 7 and 8, the direction of the arrow is the transmission direction of incident light from the incident side surface.

  If the light path changing slope A1 overlaps with the pixels of the liquid crystal cell, the display light may be insufficiently transmitted, resulting in an unnatural display, and the overlap area is made as small as possible to prevent this. It is preferable to ensure sufficient light transmittance through the gentle slope A2 or the flat surface A3. Considering that the pixel pitch of the liquid crystal cell is generally 100 to 300 μm from this point, the optical path conversion slope A1 is 40 μm or less, especially 3 to 20 μm, especially 5 to 15 μm based on the projection width with respect to the reference plane. It is preferable to form as follows. Such a projection width is more preferable than the point of preventing deterioration of display quality due to diffraction, for example, because the coherent length of the fluorescent tube is generally about 20 μm.

  On the other hand, it is preferable that the distance between the optical path conversion slopes A1 is larger than the above point, but on the other hand, the optical path conversion slope is a functional part of substantial illumination light formation by optical path conversion of side incident light as described above. If the interval is too wide, the lighting at the time of lighting may be sparse, resulting in an unnatural display. In view of these, the repetitive pitch of the optical path conversion slope A1 is 5 mm or less, especially 20 μm to 3 mm, especially 50 μm. It is preferable to be set to ˜2 mm.

  Further, in the case of an optical path changing means having a repeated structure of irregularities, moire may occur due to interference with the pixels of the liquid crystal cell. Although moiré can be prevented by adjusting the pitch of the repeating structure, there is a preferable range for the pitch of the repeating structure as described above. Therefore, a solution in the case where moire occurs in the pitch range becomes a problem. In the present invention, a method of preventing moire by forming an uneven ridge line in an inclined state with respect to the incident side surface so that a repeating structure of unevenness can be arranged in an intersecting state with respect to a pixel. 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 plane A1 is deflected and a large deviation occurs in the direction of the optical path conversion, which tends to cause deterioration in display quality. The inclination angle with respect to is preferably within ± 30 degrees, and more preferably within ± 25 degrees. Note that the sign of ± means the inclination direction of the ridge line with respect to the incident side surface. When the resolution of the liquid crystal cell is low and moire is not generated or when moire can be ignored, it is preferable that the ridge line be parallel to the incident side surface.

  The optical path control layer can be made of an appropriate material that exhibits transparency according to the wavelength range of the illumination device and has a higher refractive index than the low refractive index transparent layer. Incidentally, in the visible light region, the polymer exemplified in the above-mentioned transparent protective layer or the like, curable resin, glass 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. Moreover, the low refractive index is transparent because it suppresses the amount of lost light that cannot be emitted by being confined inside the panel due to the above-mentioned interface reflection, and efficiently supplies the side incident light or the transmitted light to the optical path control layer, particularly the optical path conversion slope A1. It is preferable that the optical path control layer has a refractive index of 0.05 or more, especially 0.08 or more, particularly 0.1 to 0.5 higher than the layer. Further, the incident light from the illuminating device or its transmitted light is efficiently incident on the optical path control layer from the viewing side substrate to achieve bright display through the optical path conversion slope, so that the refractive index difference from the viewing side substrate is 0.15. In particular, it is preferable that the optical path control layer has a refractive index higher than that of the substrate.

  The optical path control layer can be formed by a cutting method and can be formed by an appropriate method. As a preferable production method from the viewpoint of mass productivity, for example, a method of transferring a shape by pressing a thermoplastic resin to a mold capable of forming a predetermined shape under heating, a heat-melted thermoplastic resin or heat or a solvent is used. A method of filling a mold that can be molded into a predetermined shape with a fluidized resin, filling or casting a liquid resin that can be polymerized with heat, ultraviolet rays, radiation, or the like into a mold that can form a predetermined shape And a polymerization method. Therefore, the optical path control layer can be formed by directly applying the predetermined form to the viewing side substrate or the like, or can be formed as a transparent sheet or the like having the predetermined form.

  The thickness of the optical path control layer can be determined as appropriate, but is generally 300 μm or less, especially 5 to 200 μm, especially 10 to 100 μm from the viewpoint of thinning. When the optical path control layer is formed independently as a transparent sheet or the like, the transparent sheet or the like is as high as possible with an adhesive layer having a higher refractive index than the low refractive index transparent layer, especially the transparent sheet or the like. Adhesion to the liquid crystal display panel through an adhesive layer having a refractive index, in particular an adhesive layer having an intermediate refractive index between the transparent sheet or the like and the viewing side substrate, allows incident light or the like to be efficiently incident on the optical path control layer from the viewing side substrate. It is more preferable that a bright display is achieved. Therefore, the refractive index of the adhesive layer can be the same as that of the optical path control layer described above.

  The adhesive layer can be formed with an appropriate transparent adhesive, and the type of the adhesive is not particularly limited. An adhesive system using an adhesive layer is preferred from the standpoint of simplicity of the adhesive treatment work. For the formation of the adhesive layer, for example, an adhesive having a base polymer of an appropriate polymer such as rubber, acrylic, vinyl alkyl ether, silicone, polyester, polyurethane, polyether, polyamide, styrene, etc. Etc. can be used. In particular, those having excellent transparency, weather resistance, heat resistance and the like can be preferably used, such as acrylic pressure-sensitive adhesives based on polymers mainly composed of alkyl esters of acrylic acid or methacrylic acid.

  The optical path control layer is arranged on the viewing side of the liquid crystal display panel. In this case, as shown in FIGS. 1 and 2, the slope forming surface, that is, the surface on which the optical path changing means A is formed is arranged outside (viewing side). It is more preferable that the reflection efficiency through the optical path conversion inclined surface A1 of the optical path conversion means A, and the brightness improvement by effective use of side incident light, and the like.

  The outer surface of the optical path control layer may be subjected to non-glare treatment or antireflection treatment for the purpose of preventing visual obstruction due to surface reflection of external light. The non-glare treatment can be performed by making the surface a fine concavo-convex structure by various methods such as a roughening method such as a sand blasting method or an embossing method, a blending method of transparent particles such as silica, It can be applied by a method of forming a coherent vapor deposition film. Further, the non-glare treatment and the antireflection treatment can also be applied to the above-described surface fine uneven structure and the adhesion method of the film provided with the interference film.

  In the reflective liquid crystal display device according to the present invention, a light diffusion layer can be disposed as described above. The light diffusing layer can be provided by an appropriate method using a coating layer or a diffusion sheet having a surface fine concavo-convex structure according to the non-glare layer. The arrangement position of the light diffusion layer can be determined as appropriate, but in general, the arrangement between the optical path control layer and the viewing side substrate is preferable from the viewpoint of stability of display quality. In that case, the light diffusing layer is formed as a light diffusing adhesive layer by blending transparent particles, and used as a light diffusing layer that also serves as an adhesive for the transparent sheet that forms the optical path control layer or an adhesive between the polarizing plate and the retardation plate. It can also be made thinner. Therefore, one layer or two or more layers can be arranged in the light diffusion layer.

  In addition, as the transparent particles to be blended in the adhesive layer, for example, a conductive material composed of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, or the like having an average particle diameter of 0.5 to 20 μm. One kind or two kinds of suitable inorganic particles, organic particles composed of a crosslinked or uncrosslinked polymer, and the like can be used.

  According to the reflection type liquid crystal display device of the present invention, most of the incident light from the incident side surface is transmitted backward through the liquid crystal display panel, particularly the reflection side substrate, through reflection according to the law of refraction, and emitted from the panel surface ( Leakage) is prevented, and light incident on the optical path conversion slope A1 of the optical path control layer is efficiently optically path-converted in the vertical direction in the back direction, and other transmitted light is further transmitted rearward by total reflection. It is possible to achieve display with excellent brightness uniformity on the entire surface of the panel display surface by being incident on the light path changing slope A1 and being efficiently changed in the vertical direction in the back direction. Therefore, it is possible to form an external light / illumination type reflective liquid crystal display device that efficiently uses light and external light from the illumination device and is bright, easy to see, and excellent in display quality.

  In the present invention, optical elements or components such as an optical path control layer, a liquid crystal cell, a polarizing plate and a retardation plate forming the reflection type liquid crystal display device described above are bonded together in whole or in part. Alternatively, they may be arranged in an easily separated state. It is preferable to be in a fixed state from the viewpoint of preventing a decrease in contrast due to suppression of interface reflection. An appropriate transparent adhesive such as a pressure-sensitive adhesive can be used for the adhesion and adhesion treatment, and the transparent adhesive layer can contain the above-described transparent particles and the like to form an adhesive layer exhibiting a diffusion function. In addition, the above-mentioned optical elements or parts, particularly those on the viewing side, may be treated with ultraviolet rays such as salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, etc. Absorbency can also be given.

Reference example 1
Magnesium fluoride is 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, on which red, blue After forming a green striped color filter layer and an ITO transparent conductive layer in turn, the transparent electrode is etched and divided, and a polyvinyl alcohol solution is spin-coated thereon, and the dried film is rubbed to be viewed side A substrate was obtained. On the other hand, an ultraviolet curable resin layer is formed on a non-alkali glass plate similar to the above, and after roughening it, aluminum is vapor-deposited to form a diffuse reflection type electrode, and a rubbing film is provided thereon according to the above. A back side substrate was obtained.

  Next, a gap adjusting material is arranged with the rubbing surfaces of the viewing side substrate and the back side substrate facing each other so that the rubbing directions are orthogonal to each other, and the periphery is sealed with an epoxy resin, followed by liquid crystal (ZLI-4792 manufactured by Merck). To form a TN-based reflective liquid crystal cell, and a polarizing plate (NPF EGW1225DU, manufactured by Nitto Denko Corp.) with antireflection treatment and non-glare treatment on both sides is attached to a normally white reflective liquid crystal panel. Got. The panel size is 45 mm in width and 34 mm in length, and one side surface of the viewing side substrate in the length direction protrudes 2 mm from the back side substrate. Next, a cold cathode tube was placed on the protruding side surface of the viewing side substrate, surrounded by a silver-deposited polyester film, and the film ends were bonded to the upper and lower surfaces of the substrate with double-sided adhesive tape, and the cold cathode tube was held and fixed.

Reference example 2
A normally white reflective liquid crystal panel in which a cold cathode tube was held on the side surface was obtained according to Reference Example 1 except that the thickness of the low refractive index transparent layer made of magnesium fluoride was 300 nm.

Reference example 3
A normally white reflective liquid crystal panel in which a cold cathode tube was held on the side surface according to Reference Example 1 was obtained except that the thickness of the low refractive index transparent layer made of magnesium fluoride was 100 nm.

Reference example 4
A normally white reflective liquid crystal panel in which a cold cathode tube was held on the side surface according to Reference Example 1 was obtained except that a low refractive index transparent layer made of magnesium fluoride was not provided on the viewing side substrate.

Reference Example 5
The cold cathode fluorescent lamps are held on both side surfaces according to Reference Example 1 except that the opposite side surface of the viewing side substrate in the length direction has a panel size of 45 mm wide and 36 mm long protruding 2 mm from the back side substrate. A normally white reflective LCD panel was obtained.

Reference Example 6
A normally white reflective liquid crystal panel in which cold cathode tubes were held on both sides according to Reference Example 5 was obtained except that a low refractive index transparent layer made of magnesium fluoride was not provided on the viewing side substrate.

Reference Example 7
An acrylic UV curable resin (Aronix UV-3701, manufactured by Toagosei Co., Ltd.) is dropped into a mold that has been processed into a predetermined shape with a dropper, and a triacetyl cellulose (TAC) film (thickness 80 μm) ( The surface saponification product, refractive index 1.49) is allowed to stand and adhered with a rubber roller to remove excess resin and bubbles, and cured by irradiating with a metal halide lamp with ultraviolet rays, and then peeled off from the mold to a predetermined dimension. A transparent sheet having an optical path control layer having a refractive index of 1.51 was obtained, and an adhesive layer having a refractive index of 1.47 was provided on the surface not having the optical path control layer.

  The transparent sheet has a width of 40 mm and a length of 30 mm, and has prism-like concave portions whose ridgelines are inclined at an angle of 21 degrees across the width direction at a pitch of 210 μm (FIG. 3c), and its optical path changing slope The inclination angle of A1 is 42 degrees, the inclination angle of the gentle slope A2 is 1.8 to 3.5 degrees, the inclination angle change of the nearest gentle slope is within 0.1 degree, and the projection to the reference plane of the optical path conversion slope The width is 10 to 16 μm, and the projected area ratio of the gentle slope / optical path conversion slope to the reference plane is 12 times or more.

Reference Example 8
An optical path control layer having a refractive index of 1.51 is formed in accordance with Reference Example 7 using a polycarbonate film having a thickness of 60 μm instead of a TAC film, and a transparent sheet made of the optical path control layer itself is peeled off from the polycarbonate film. Thus, an adhesive layer having a refractive index of 1.51 was provided on the surface not having the optical path control layer. The transparent sheet has a width of 40 mm and a length of 30 mm, and has prism-shaped concave portions whose ridgelines are inclined at an angle of 21 degrees across the width direction at a pitch of 210 μm (FIG. 3 b). The tilt angle of A1 is 42 degrees, the apex angle with the steep slope A2 is 70 degrees, the projection width of the optical path conversion slope with respect to the reference plane is 10 to 16 μm, and the area of the flat portion (A3) is with respect to the reference plane of the optical path conversion slope and the steep slope It consists of more than 10 times the total projected area.

Reference Example 9
Using a different mold, a transparent sheet with an adhesive layer comprising the optical path control layer itself was obtained according to Reference Example 8. This transparent sheet has an optical path conversion means (FIG. 3b) having a length of 80 μm, comprising an optical path conversion slope A1 having an inclination angle of about 42 degrees and a projection width of 10 μm with respect to the reference plane, and a steep slope A2 having an inclination angle of about 65 degrees. The optical path changing means is arranged in a state where the vertical direction is parallel to the incident side surface and the density is gradually increased as the distance from the incident side surface in the length direction increases (FIGS. 6 and 8). The area of A3) 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 10
Using a different mold, a transparent sheet with an adhesive layer comprising the optical path control layer itself was obtained according to Reference Example 9. This transparent sheet has an optical path changing means (FIG. 3a) having an isosceles triangle formed of an isosceles triangle with an inclination angle of about 42 degrees and a projection width with respect to a reference plane of 10 μm, and whose length direction is on the incident side surface. The optical path changing means are arranged in a parallel state and are randomly arranged so as to gradually increase in density from the incident side surface in the length direction toward the central portion (FIG. 6), and the flat portion (A3) Is at least 10 times the projected total area of the optical path conversion slope and the steep slope with respect to the reference plane.

Reference Example 11
A transparent sheet with an adhesive layer consisting of the optical path control layer itself was obtained in accordance with Reference Example 8 except that the surface of the mold was roughened by sandblasting.

Reference Example 12
Using a different mold, a transparent sheet with an adhesive layer comprising the optical path control layer itself was obtained according to Reference Example 8. This transparent sheet has prism-shaped concave portions continuously at a pitch of 210 μm (FIG. 3 b), the inclination angle of the optical path conversion slope A 1 is 30 degrees, the apex angle with the steep slope A 2 is 70 degrees, and the reference of the optical path conversion slope The projected width with respect to the plane is 10 to 16 μm, and the area of the flat portion (A3) is more than 10 times the total projected area of the optical path conversion slope and steep slope with respect to the reference plane.

Example 1
The transparent sheet of Reference Example 7 was bonded to the surface on the viewing side of the reflective liquid crystal panel of Reference Example 1 via the adhesive layer to obtain an external light / illumination type reflective liquid crystal display device.

Comparative Example 1
The transparent sheet of Reference Example 7 was adhered to the viewing-side surface of the reflective liquid crystal panel of Reference Example 4 via the adhesive layer to obtain an external light / illumination reflective liquid crystal display device.

Example 2
The transparent sheet of Reference Example 8 was bonded to the viewing-side surface of the reflective liquid crystal panel of Reference Example 1 via the adhesive layer to obtain an external light / illumination type reflective liquid crystal display device.

Example 3
The transparent sheet of Reference Example 8 was bonded to the surface on the viewing side of the reflective liquid crystal panel of Reference Example 2 via the adhesive layer to obtain an external light / illumination type reflective liquid crystal display device.

Example 4
The transparent sheet of Reference Example 8 was adhered to the viewing-side surface of the reflective liquid crystal panel of Reference Example 3 via the adhesive layer to obtain an external light / illumination reflective liquid crystal display device.

Comparative Example 2
The transparent sheet of Reference Example 8 was bonded to the viewing side surface of the reflective liquid crystal panel of Reference Example 4 via the adhesive layer to obtain an external light / illumination reflective liquid crystal display device.

Comparative Example 3
The transparent sheet of Reference Example 11 was adhered to the viewing side surface of the reflective liquid crystal panel of Reference Example 1 via the adhesive layer to obtain an external light / illumination type reflective liquid crystal display device.

Comparative Example 4
The transparent sheet of Reference Example 12 was bonded to the viewing side surface of the reflective liquid crystal panel of Reference Example 1 via the adhesive layer to obtain an external light / illumination reflective liquid crystal display device.

Example 5
The transparent sheet of Reference Example 9 was bonded to the viewing-side surface of the reflective liquid crystal panel of Reference Example 1 via the adhesive layer to obtain an external light / illumination reflective liquid crystal display device.

Comparative Example 5
The transparent sheet of Reference Example 9 was adhered to the viewing-side surface of the reflective liquid crystal panel of Reference Example 4 via the adhesive layer to obtain an external light / illumination reflective liquid crystal display device.

Example 6
The transparent sheet of Reference Example 10 was bonded to the viewing-side surface of the reflective liquid crystal panel of Reference Example 5 via the adhesive layer to obtain an external light / illumination reflective liquid crystal display device.

Comparative Example 6
The transparent sheet of Reference Example 10 was bonded to the surface on the viewing side of the reflective liquid crystal panel of Reference Example 6 via the adhesive layer to obtain an external light / illumination type reflective liquid crystal display device.

Evaluation Test Regarding the reflective liquid crystal display devices obtained in the examples and comparative examples, the cold cathode tube was turned on without applying voltage to the liquid crystal cell in the dark room, and the position was 5 mm from the incident side, 5 mm from the center and the opposite end. The front luminance at was measured with a luminance meter (BM7, manufactured by Topcon). Moreover, the display quality when the display by the illumination mode was observed in the front direction, the incident side surface side, and the opposite end side at 15 degrees was evaluated. The evaluation was ○ when the light was bright and excellent in uniformity and light was emitted well, Δ when the brightness and uniformity were slightly inferior, and × when it was dark and non-uniform.

The results are shown in the following table.
Front luminance (cd / m ² ) display quality
Incident side face Center part Opposite end incident side face Front direction Opposing end side
Example 1 34 31 29 ○ ○ ○
Comparative Example 1 30 8 4 × × ×
Example 2 35 32 36 ○ ○ ○
Example 3 38 30 26 Δ ○ ○
Example 4 34 25 21 Δ Δ ○
Comparative Example 2 29 8 5 × × ×
Comparative Example 3 4 6 6 × × ×
Comparative Example 4 10 8 12 × × Δ
Example 5 36 37 34 ○ ○ ○
Comparative Example 5 31 10 4 × × ×
Example 6 68 51 54 ○ ○ ○
Comparative Example 6 41 35 39 × △ ×

  From the table, it can be seen that bright and uniform display is achieved in the illumination mode in the example, but the display is very dark or non-uniform in the comparative example. Further, it can be seen that, as the thickness of the low refractive index transparent layer is larger than in Examples 2, 3, and 4, the characteristics at the incident side surface are improved and the brightness uniformity is increased. However, in Comparative Examples 1, 2, 5, and 6 that do not have a low refractive index transparent layer, it becomes darker as it gets farther from the incident side surface, and it can be seen that there is a large nonuniformity of brightness that seems to be absorbed by the color filter layer, The display was very difficult to see. In Comparative Example 6, the luminance appears to be uniform on the table, but the uniformity greatly changed due to the change in the viewing angle in the direction of the incident side surface, and it was difficult to see with a very unnatural display. Also, the luminance itself is inferior to that of Example 6.

  Furthermore, in Comparative Example 3 in which the surface of the transparent sheet was roughened and in Comparative Example 4 in which the angle of the prism slope was small, light was not emitted effectively and was dark. In the case of the example, the voltage was applied to the liquid crystal display device and the display was observed, but the display was satisfactory with no particular problem in both the illumination mode and the external light mode. However, in the comparative example, there was no problem in the outside light mode, but it was difficult to see in the illumination mode. As described above, in the present invention, it is possible to form a reflective liquid crystal display device with good display quality by achieving thin and light weight by the optical path control layer method while avoiding bulkiness and heavy weight by using the light guide plate. Recognize.

Cross-sectional view of an example of a reflective liquid crystal display device for both external light and illumination Cross-sectional view of another example of reflection type liquid crystal display device for both external light and illumination Side view of optical path changing means in optical path control layer Still another perspective view of a reflective liquid crystal display device example Still another perspective view of a reflective liquid crystal display device example Still another perspective view of a reflective liquid crystal display device example Side surface explanatory diagram of an example of an optical path control layer Side view of another example of optical path control layer

Explanation of symbols

11: Optical path control layer A: Optical path conversion means (A1: Optical path conversion slope)
1, 2, 3, 4, 5: Liquid crystal display panel 12, 15: Polarizing plate 13, 14: Phase difference plate 21: Transparent substrate (viewing side substrate)
22: Low refractive index transparent layer 23: Color filter 24: Transparent electrode 25, 41: Alignment film 43, 45: Back side substrate 42, 44: Electrode 31: Liquid crystal 16, 42: Reflective layer 51, 53: Illumination device

Claims (19)

A liquid crystal cell in which a liquid crystal is sandwiched between a transparent substrate having a transparent layer having a refractive index lower than that of the substrate, a transparent substrate having a transparent electrode, and a rear substrate having an electrode facing each other with the electrodes facing each other; The reflective liquid crystal display panel having at least a reflective layer on the back substrate side has an illumination device on one or more side surfaces, and an inclination angle with respect to a reference plane of the substrate is outside the viewing side substrate. A reflective liquid crystal display device having an optical path changing slope of 35 to 48 degrees and an optical path control layer having a refractive index higher than that of the low refractive index transparent layer. 2. The reflective 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 transparent electrode, and the refractive index difference from the transparent substrate is 0.05 or more. 3. The reflective liquid crystal display device according to claim 1, wherein at least the viewing side substrate of the liquid crystal cell is made of an optically isotropic material. 4. The reflective liquid crystal display device according to claim 1, wherein the liquid crystal display panel has a polarizing plate on one side or both sides of the liquid crystal cell. 5. The reflective liquid crystal display device according to claim 4, wherein the liquid crystal display panel has one or more retardation plates between the liquid crystal cell and the polarizing plate. 6. The reflective liquid crystal display device according to claim 1, wherein the optical path control layer has a repetitive structure of prismatic irregularities, and the optical path conversion slope faces the illumination device. 7. The reflection type liquid crystal display device according to claim 6, wherein the prismatic irregularities of the optical path control layer are concave portions having a substantially triangular cross section. 8. The reflective liquid crystal display device according to claim 7, wherein the prism-shaped concave portion includes a continuous groove extending from one end to the other end of the optical path control layer in a ridge line direction parallel to or inclined to the side surface of the liquid crystal display panel on which the illumination device is disposed. 8. The reflective liquid crystal display device according to claim 7, wherein the prism-shaped concave portion is a discontinuous groove, and the length of the groove is five times or more the depth. 10. The reflective liquid crystal display device according to claim 9, wherein the length direction of the discontinuous grooves of the prism-shaped recess is substantially parallel to the side surface of the liquid crystal display panel on which the illumination device is disposed. 10. The reflective liquid crystal display device according to claim 7, wherein the prism-shaped concave portion is formed of a discontinuous groove, and the discontinuous grooves are randomly arranged. The reflective liquid crystal display device according to claim 6, wherein the prism-like unevenness of the optical path control layer has two or more optical path conversion slopes facing the illuminating device. The reflective liquid crystal display device according to claim 12, wherein the liquid crystal display panel includes an illumination device on two or more side surfaces. 14. The reflection type 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. 15. The reflection type liquid crystal display device according to claim 1, wherein the optical path control layer is made of a transparent sheet and is adhered to the liquid crystal display panel through an adhesive layer having a higher refractive index than that of the transparent layer having a low refractive index. 16. The reflective liquid crystal display device according to claim 15, wherein the adhesive layer is an adhesive layer. 17. The reflective liquid crystal display device according to claim 1, wherein the refractive index of the optical path control layer and the adhesive layer is 0.05 or more higher than that of the transparent layer having a low refractive index. 18. The reflective liquid crystal display device according to claim 1, wherein a side surface formed by the viewing side substrate protrudes from a side surface formed by the back side substrate, and the lighting device is disposed on the projecting side surface of the viewing side substrate. The lighting device according to any one of claims 1 to 18, wherein the illumination device is surrounded by a light reflection type light source holder, and is attached to the end portions of the upper and lower surfaces of the viewing side substrate through the end portions of the light source holder. A reflection type liquid crystal display device which is arranged and held.

Images