JP2005221619A - Optical sheet, back-light, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet, back-light, and a liquid crystal display device, which can be improved in control of a diffusion angle of outgoing light from a light source and in a utilization factor of the outgoing light to realize high luminance, an appropriate viewing angle, and high contrast without using a diffuser having strong diffuseness. <P>SOLUTION: The optical sheet is a light transmissive member having a lens surface where two or more lenses formed convex at a predetermined pitch and a flat surface, which is provided with a light reflecting part 5 and a light transmissive part 6 in an area including non-condensing surfaces of the lenses, and as to the light made to exit from a linear light source 8 to the optical sheet 1, the light reflected by the light reflecting part 5 is reflected by a reflecting layer 10 of the inner surface of the case 9, and goes to the light reflecting part 5 or the light transmissive part 6 again, and the light passing through the light transmissive part 6 is made incident to the lenses and made to exit from the back-light 50 with the exit angle controlled by the condensing action of the lenses, and made incident to a liquid crystal panel 60. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical sheet that diffuses emitted light from a light source such as a cold cathode fluorescent lamp (CCFT) or an LED (Light Emitting Diode), and a back that transmits the emitted light from the back side of a transmissive image display panel such as a liquid crystal display device. The present invention relates to a light and a liquid crystal display device.

  In recent years, liquid crystal display devices using liquid crystal panels have been used as image display means for notebook personal computers in the OA field, displays for personal computers, information terminal devices, etc., information display equipment for information appliances such as large-screen TVs, and mobile phones. In addition, it has been used in various fields as an image display means for personal digital assistance (PDA). Such a liquid crystal display device is a transmissive type, and a light source is provided on the back side of the liquid crystal panel, and a surface light source device that irradiates the liquid crystal panel by converting light from the light source into surface light emission, a so-called backlight is provided. It has been adopted. Such a backlight method is roughly divided into a light source such as a cold cathode fluorescent tube (CCFT) along a side end portion of a flat light guide plate made of acrylic resin having excellent light transmittance. There are a light guide plate light guide method (edge light method) in which light from the light source is multiply reflected within the light guide plate, and a direct type method in which a light source is arranged on the back of a liquid crystal panel that does not use the light guide plate.

  Recently, for a small-sized liquid crystal display device of 20 inches or less used for a notebook personal computer or a portable information terminal, a light guide light guide system which can achieve low power consumption and can be easily thinned has become mainstream. The direct type is used.

  A liquid crystal display device equipped with a general light guide plate light guide type backlight has, for example, a color filter sandwiched between a transparent substrate and a polarizing plate at the top, a liquid crystal panel composed of a liquid crystal layer, and a backlight on the lower surface side. Is provided.

  The backlight has a light guide plate made of transparent PMMA (polymethyl methacrylate) or the like having a substantially rectangular plate shape, a diffusion film (diffusion layer) on the light emission surface on the upper surface side of the light guide plate, A scattering / reflection pattern part (printing pattern, groove, dot, etc.) that scatters and reflects light introduced into the light guide plate efficiently and uniformly in the direction of the liquid crystal panel 31 is formed. (Reflective layer) is provided. A light source is attached to the light guide plate along the side edge, and a high-reflectance lamp reflector is provided so as to cover the back side of the light source that allows light from the light source to enter the light guide plate efficiently.

The scattering reflection pattern part is formed by printing a mixture of white titanium dioxide (TiO ₂ ) powder mixed with a transparent resin in a dot shape, for example, a cone shape, a convex lens shape, a Mt. Fuji dot or a V-shaped groove. It can be formed by injection molding or hot pressing together with the molding of the light guide plate. This scattering reflection pattern portion imparts directivity to the light incident on the light guide plate and guides the light toward the light exit surface, and is one means for increasing the brightness.

  Furthermore, it has been proposed to provide a prism film (prism layer) having a light condensing function between the diffusion film and the liquid crystal panel in order to improve the light utilization efficiency and increase the luminance. This prism film collects the light emitted from the light exit surface of the light guide plate and diffused by the diffusion film with high efficiency on the effective display area of the liquid crystal panel.

  A liquid crystal display device equipped with a general direct type backlight has, for example, a color filter sandwiched between a transparent substrate and a polarizing plate at the top, a liquid crystal panel composed of a liquid crystal layer, and a backlight on the lower surface side. It has been.

  The backlight is composed of a plurality of light sources extending in a columnar shape in a housing having an opening on the front surface, a highly reflective reflective layer disposed inside the housing, and a diffusion plate that diffuses emitted light. Yes.

  The direct type method consumes more power by using multiple light sources than the light guide plate light guide method, but the light guide is unnecessary and the surface brightness can be kept high even if the screen is enlarged. Therefore, a direct type is often used as a backlight of a large liquid crystal display device.

  However, in the direct type, light directed directly from the light source to the viewer side (liquid crystal panel side) is emitted as diffused light, so that it is recognized that the directivity of the light from the light source 47 is reduced, and the viewing angle dependency There is a problem that it does not lead to improvement. The viewing angle dependency is, for example, what is supposed to be displayed in black when the liquid crystal display device is observed from a direction of a certain angle or more, or a decrease in contrast due to gradation inversion, contrast inversion, etc. , It means that there is a state where the observer cannot see the image accurately. The reason why this viewing angle dependency occurs is mainly due to the twist of the liquid crystal molecules, the refractive index anisotropy of the liquid crystal molecules, the polarization characteristics of the polarizing plate, and the surface light source.

  Furthermore, the cold cathode tube (CCFT) or LED (Light Emitting Diode) as a light source can directly recognize the shape of the emitted light source through the diffusion plate that diffuses the emitted light. A strong resin plate is used. This diffuser plate usually needs to have a thickness of about 1 mm to 3 mm in order to give strong diffusibility, and because of its thickness, there is not a little light absorption, and the amount of light from the light source is reduced and the liquid crystal display is displayed. There is a problem of darkening.

  The diffuser plate has a high total light reflectance of about 30 to 50% due to its strong light diffusivity, and it can be reused for light reflected by the reflective layer disposed on the lower surface of the light source. Since the reflectance of the layer is not 100%, the amount of light that can be reused decreases with each reflection between the reflective layer and the diffuser, and the total amount of light from the light source does not reach the liquid crystal panel side. There is a problem that the liquid crystal display screen becomes dark.

  Furthermore, because of the strong light diffusibility, the diffuser has a characteristic of diffusing light in a direction that is not used for actual display (generally, an angle deeper than ± 60 degrees in both the top, bottom, left and right). In addition, the light emitted at such a deep angle is not effectively used for displaying a liquid crystal image, but also leads to a decrease in contrast of the display image.

  For the purpose of narrowing the angle of the light emitted from the light source, one to several light scattering films obtained by treating the surface of a resin film called a diffusion sheet on a normal diffusion plate in a mat shape, the mat surface Is arranged at a position facing the opposite side of the diffusion plate. This diffusion sheet forms a matte surface on the surface of the resin film by physical treatment such as sand blasting or chemical treatment such as dissolution treatment, and controls the light scattering by the surface roughness. It is difficult to control. In addition, since the diffusion angles cannot be different from each other up and down, left and right, even if this diffusion sheet is used, light that is effective for display cannot be obtained, and the problem that the liquid crystal display screen becomes dark due to a decrease in the amount of light remains.

  If the above diffusion sheet alone is not sufficient, when one or two prism sheets are used orthogonally, the direct-type backlight has the highest intensity light emitted vertically from the light source directly on the prism surface. Although the light reflected and reflected by the reflective layer on the lower surface of the light source can be reused, the reflectance of the reflective layer on the lower surface of the light source is not 100%, so the reusable amount of light is reflected between the reflective layer and the diffuser. Since the total light quantity from the light source does not reach the liquid crystal panel, the liquid crystal display screen becomes dark due to the decrease in the light quantity.

In addition, when a prism sheet is used, there is a disadvantage that about 10% of emitted light is emitted at a deep angle that cannot be used for displaying a liquid crystal image.
Japanese Patent Laid-Open No. 2-118518 JP-A-8-136923 JP-A-10-104622 JP 2002-278470 A JP-A-8-122774 JP 2002-284268 A Japanese Patent Laid-Open No. 6-18707

  By the way, a large-sized liquid crystal display device of 20 inches or more is required to be thinner, have a low viewing angle dependency, have high luminance, and have low power consumption, and is mounted on the liquid crystal display device. Backlights are also required to deal with that realization.

  In particular, as described above, the configuration of the conventional direct type backlight needs to have a strong diffusivity for the emitted light from the surface light source to the diffuser plate, and the diffuser plate absorbs and reflects the emitted light. The problem of a decrease in the amount of transmitted light due to generation, the problem of a decrease in the amount of transmitted light due to an increase in the thickness of the entire backlight, including the thickness of the diffuser plate and the thickness of laminated diffusion sheets, prism sheets, etc. There is a problem of direct image generation of the light source through the light, and the light is diffused in such a direction that the emitted light is not used for the display of the liquid crystal display device (generally an angle deeper than ± 60 degrees in both the top, bottom, left and right). There are problems such as a problem that the efficiency is low and the contrast is lowered.

  Therefore, the present invention has been made in view of the above-described problems. In order to realize high luminance, an appropriate viewing angle, high contrast, and the like without using a diffuser plate having strong diffusibility, the present invention has been made. An object of the present invention is to provide an optical sheet and a backlight, and a liquid crystal display device capable of controlling the diffusion angle of the emitted light and improving the utilization efficiency of the emitted light.

  The present invention solves such a problem, and the invention according to claim 1 is a light transmissive material having a lens surface and a flat surface in which a plurality of lenses formed in a convex shape at a predetermined pitch are arranged. An optical sheet, wherein the flat surface is provided with a light reflecting portion in a region including a non-light condensing surface of the lens and a light transmitting portion in a region other than the light reflecting portion. .

  The invention according to claim 2 is a light-transmitting member having a lenticular lens surface and a flat surface in which a plurality of convex cylindrical lenses formed at a predetermined pitch are arranged in parallel, and the flat surface The optical sheet is characterized in that a longitudinally striped light reflecting portion is provided in a region including a non-light-condensing surface of the cylindrical lens, and a light transmitting portion is provided in a region other than the light reflecting portion. .

  According to a third aspect of the present invention, in the optical sheet according to the second aspect, a plurality of sets in which a plurality of cylindrical lenses of the lenticular lens are arranged in parallel are arranged at intervals.

  According to a fourth aspect of the present invention, there is provided a cross lenticular lens surface in which a plurality of convex cylindrical lenses formed at a predetermined pitch are arranged in parallel in the vertical and horizontal directions so as to intersect on the same plane in the longitudinal direction. A light transmitting member having a flat surface, wherein the flat surface is provided with a light reflecting portion in a region including a non-condensing surface of the cylindrical lens and a light transmitting portion in a region other than the light reflecting portion. An optical sheet characterized by the above.

  According to a fifth aspect of the present invention, in the optical sheet according to the fourth aspect, a set in which a plurality of cylindrical lenses in any one of the longitudinal and transverse directions intersecting on the same plane of the cross lenticular lens are arranged in parallel is spaced apart. In this case, a plurality of sets are arranged.

  According to a sixth aspect of the present invention, in the optical sheet of the fourth or fifth aspect, any one of the cylindrical lens diameters in the vertical and horizontal directions intersecting on the same plane of the cross lenticular lens is larger than the diameter of the other cylindrical lens. It is large.

  According to a seventh aspect of the present invention, in the optical sheet according to the fourth to sixth aspects, the light transmission portion is included in a region where the cylindrical lens of the cross lenticular lens intersects in the vertical and horizontal directions.

  The invention according to claim 8 is a light-transmitting member having a microlens array having a plurality of fine convex microlenses and a flat surface, and the flat surface has a non-light-collecting surface of the microlens. An optical sheet comprising: a light reflecting portion in a region including the light reflecting portion; and a light transmitting portion in a region other than the light reflecting portion.

  According to a ninth aspect of the present invention, in the optical sheet according to any one of the first to eighth aspects, the light transmissive member has a lens portion formed on a light transmissive substrate.

  According to a tenth aspect of the present invention, in the optical sheet according to the first to eighth aspects, the light transmitting portion is an opening of the light reflecting portion.

  The invention according to claim 11 is the optical sheet according to any one of claims 1 to 8, wherein a vapor deposition part is provided between the light reflecting part and the flat surface.

  According to a twelfth aspect of the present invention, in the optical sheet according to the first to eighth aspects, the reflecting portion is located inside the light transmissive member with respect to the flat surface.

  A thirteenth aspect of the present invention is the optical sheet according to the first to eighth aspects, wherein a protective layer is formed on the light reflecting portion and the light transmissive member including the light reflecting portion.

  According to a fourteenth aspect of the present invention, in the optical sheet according to the first to eighth aspects, the protective layer has an ultraviolet absorbing function.

  According to a fifteenth aspect of the present invention, in the optical sheet according to the first to eighth aspects, the protective layer has a fluorescent substance.

  A sixteenth aspect of the invention is an optical sheet obtained by laminating an inflexible resin sheet on the optical sheet of the first to fifteenth aspects.

  The invention described in claim 17 is characterized in that, in the optical sheet described in claim 16, a filler is mixed into the resin sheet.

  The invention according to claim 18 is characterized in that, in the optical sheet according to claim 16, the resin sheet is composed of multiple layers, and fillers are mixed in all or a part of the layers.

  The invention according to claim 19 is the optical sheet according to any one of claims 16 to 18, wherein the resin sheet is composed of a plurality of layers, and the surface of all or a part of the layers is subjected to a mat treatment. .

  The invention according to claim 20 has one or more linear light source devices and a lens surface and a flat surface formed by arranging a plurality of convexly formed lenses at a predetermined pitch, and The flat surface is formed by superimposing a reflection portion in a region including the non-light-condensing surface of the lens and an optical sheet provided with a light transmission portion in a region other than the reflection portion, from the linear light source device. The backlight is characterized in that irradiation light is emitted through the light transmission part.

  The invention according to claim 21 is the backlight according to claim 20, wherein the optical sheet is the optical sheet according to claims 2 to 19.

  The invention according to claim 22 is the backlight according to claim 20 or 21, wherein the linear light source of the linear light source device and the cylindrical lens formed in the longitudinal direction of the optical sheet are parallel or have an angle. It is characterized by that.

  The invention according to claim 23 has one or a plurality of linear light source devices, a lens surface having a plurality of lenses formed in a convex shape at a predetermined pitch, and a flat surface. Is formed by superimposing an optical sheet, a liquid crystal panel, and a color filter, each of which includes a reflection portion in a region including a non-light-condensing surface of the lens and a light transmission portion in a region other than the reflection portion. The liquid crystal display device is characterized in that irradiation light from a light source device is emitted toward the liquid crystal panel through the light transmission portion.

  According to a twenty-fourth aspect of the present invention, in the liquid crystal display device according to the twenty-third aspect, the optical sheet is the optical sheet according to any one of the second to nineteenth aspects.

  The invention according to claim 25 is the liquid crystal display device according to claim 23 or 24, wherein the linear light source of the linear light source device and the cylindrical lens formed in the longitudinal direction of the optical sheet are parallel or at an angle. It is characterized by having.

  According to the present invention, the direction of the lens of the lens sheet constituting the optical sheet is arranged substantially parallel to the direction of the linear light source or at a predetermined angle, so that the emitted light from the light source is reduced and imaged by each lens. As a result, the same number of thin light source images as the number of lenses are arranged on the optical sheet, so that the direct image of the light source cannot be seen from the observer side, and a planar light source, that is, a surface light source can be obtained. it can. Accordingly, it is not necessary to use a thick diffuser plate having a strong diffusivity as in the prior art, and light loss can be suppressed.

  In the backlight and liquid crystal display device using the optical sheet of the present invention, the display image is bright (high luminance), power consumption can be reduced, and the viewing angle is widened with the same brightness (low viewing angle dependency). Play.

  Further, in the present invention, the diffusion of the emitted light is controlled by controlling the lens interval of the lens sheet constituting the optical sheet, the refractive index of the resin constituting the lens, the base sheet, and the size of the light transmission part (opening). The angle can be controlled, and the emitted light is diffused and emitted only within the range that can be effectively used for image display. Therefore, in the backlight and liquid crystal display device using the optical sheet, the display image is bright (high brightness), high contrast, and consumption There is an effect that the power can be reduced and the viewing angle is widened with the same brightness (low viewing angle dependency).

  Furthermore, in the present invention, most of the emitted light from the linear light source has the highest intensity, and the emitted light is perpendicular to the observer, and most of the emitted light directly passes through the light transmitting portion (opening) of the lens sheet and the lens directly. Since light is transmitted, loss of light due to repeated reflection of the conventional diffuser can be suppressed, and thus, in a backlight and a liquid crystal display device using an optical sheet, a display image is bright (high luminance) and power consumption can be reduced. The effect is that the viewing angle widens (low viewing angle dependency) with the same brightness.

  In the present invention, since the light reflecting portion of the optical sheet has a two-layer structure with the vapor deposition portion, the reflectance of light in the optical sheet in the region other than the light transmitting portion (opening portion) is increased, thereby suppressing light loss. Therefore, in a backlight and a liquid crystal display device using an optical sheet, the display image is bright (high luminance), power consumption can be reduced, and the viewing angle is widened with the same brightness (low viewing angle dependency). The effect to do.

  In the present invention, the protective layer is provided on the light transmissive member including the light reflecting portion of the optical sheet, thereby improving the abrasion resistance of the optical sheet and reducing the occurrence of defects such as damage to the optical sheet in the backlight manufacturing process. The effect is to increase the rate and lower the cost.

  In the present invention, by containing an ultraviolet absorber in the protective layer of the optical sheet, the ultraviolet light from the light source is reduced and the light resistance of the optical sheet of the present invention is increased, thereby protecting the observer and the optical sheet. The effect of prolonging the product life of the backlight and the liquid crystal display device using this is achieved.

  In the present invention, by including a fluorescent substance in the protective layer of the optical sheet, it becomes possible to convert the ultraviolet light contained in the light emitted from the cold cathode tube, which is the light source, into visible light. Since the amount of light can be used effectively without increasing it, the display image is bright (high luminance) and the power consumption can be reduced.

  Embodiments of the present invention will be described.

  FIG. 1 is a schematic cross-sectional view showing one structural example of the optical sheet 1 of the present invention. FIG. 15 is a schematic sectional view showing a configuration example of the backlight 50 of the present invention, and FIG. 16 is a schematic sectional view showing a configuration example of the liquid crystal display device 60 of the present invention.

  The optical sheet 1 diffuses the emitted light from the linear light source 48 in the backlight 50 and the liquid crystal display device 60 incorporating the backlight 50 as a surface light source, and diffuses the emitted light so that the emitted light is emitted in a planar shape. The emitted light can be diffused and emitted only within a range that can be effectively used for image display.

  The configuration of the optical sheet 1 is a light transmissive member 7 having a lens surface 3 and a flat surface 4 in which a plurality of lenses 2 formed in a convex shape at a predetermined pitch are continuously arranged. In this embodiment, the light reflecting portion 5 and the light transmitting portion 6 are provided in a region other than the light reflecting portion 5 in a region including the non-condensing surface of the lens 2. The light emitted from the linear light source 48 shown in FIG. 15 or 16 toward the optical sheet 1 is divided into light reflected by the light reflecting portion 5 and light transmitted through the light transmitting portion 6 in the flat portion 4. It is done. The light reflected by the light reflecting portion 5 is reflected by the reflecting layer 10 on the inner surface of the housing 9 and travels again toward the light reflecting portion 5 or the light transmitting portion 6. On the other hand, the light transmitted through the light transmitting portion 6 enters the lens 2, the emission angle is controlled by the condensing function of the lens, the light is emitted from the backlight 50, and enters the liquid crystal panel.

  At this time, the light emitted from the light source is directly reduced and formed on each lens 2 by the lens 2, and the same number of thin light source images as the number of the lenses 2 are arranged on the optical sheet 1. The optical sheet 1 becomes a planar light source that emits light uniformly without any direct image being reflected. As a result, it is not necessary to use a conventional thick and highly diffusible diffusion plate, and light loss can be suppressed.

  The light-transmitting member 7 is light-transmitting, preferably an acrylic acid ester such as polymethyl methacrylate and polymethyl acrylate having a refractive index of about 1.4 to 1.7, or a single methacrylic acid ester. Or it consists of materials, such as a copolymer, polyesters, such as a polyethylene terephthalate and a polybutylene terephthalate, resin, such as a polycarbonate and a polystyrene, glass, ceramics. The thickness of the light transmissive member 7 is about 50 to 500 μm, and the pitch of the lenses 2 is appropriately selected according to the application, but is about 20 to 1000 μm. Examples of the method for forming the light transmissive member 7 including the lens surface 3 include extrusion molding or hot press molding of a thermoplastic resin, and injection molding.

  FIG. 2 is a schematic cross-sectional view showing another configuration example of the optical sheet 1 of the present invention. After the lens 2 is formed on the base sheet 8, an ultraviolet curable resin or an electron beam curable resin is applied to the base sheet 8, and embossing is performed with a roll embossing plate in which a lens-shaped mold is formed. Then, the resin is cured by irradiating ultraviolet rays or an electron beam to form the lens 2. The thickness of the base sheet 8 is about 30 to 300 μm, the height of the lens 2 is about 5 to 200 μm, and the pitch of the lenses 2 is appropriately selected according to the application, but is about 20 to 1000 μm. .

  Types of the lens 2 include a lenticular lens array 11 that is a semi-cylindrical cylindrical lens shown in FIG. 3, a cross lenticular lens array 12 that intersects a semi-cylindrical cylindrical lens shown in FIG. 4, a spherical surface shown in FIG. There is a microlens array 13 in which a large number of convex unit lenses having an aspherical surface, different curvatures in the vertical and horizontal directions, or an aspheric toric shape are arranged on a sheet surface.

  Further, the lenticular lens array 14 in which a plurality of sets of cylindrical lenses shown in FIG. 6 are arranged in parallel is arranged at intervals, and the cross and lenticular lenses shown in FIG. Cross lenticular lens array 15 in which a plurality of sets of cylindrical lenses of any one of the directions arranged in parallel are arranged at intervals, on the same plane of the cross lenticular lenses shown in FIGS. 7B and 7C There are cross lenticular lens arrays 16 and 17 in which one of the cylindrical lens diameters in the vertical and horizontal directions intersecting with each other is larger than the diameter of the other cylindrical lens.

  The light emitted from the linear light source 48 passes through the light transmission part 6 that is an opening and enters the lens 2. Light emitted from the vicinity including the lens condensing surface is emitted from the lens surface 3 as light in a certain direction by the lens 2. Thereby, the direction of the light emitted from the lens surface 3 can be controlled by the size of the light transmission part 6 (opening part).

  That is, the smaller the size of the light transmitting portion 6 (opening), the stronger the directivity of the light emitted from the light source. Conversely, if the light transmitting portion 6 (opening) is increased, the directivity is reduced and the degree of diffusion is increased. Further, by changing the shape of the opening, it is possible to control the diffusibility according to the direction. For example, if an opening that is large in the horizontal direction and small in the vertical direction is used, a wide observation area can be taken in the horizontal direction with respect to the vertical direction. Since the viewing area in the vertical direction is generally small as a liquid crystal characteristic, the light utilization efficiency can be further enhanced by setting the backlight characteristic to be a narrow viewing area in the vertical direction in advance. Furthermore, the observation region of the liquid crystal panel can be divided by setting the number of openings for one lens to a plurality. In this way, the observation area can be freely controlled by various aperture shapes.

  The shape of the light reflecting portion 5 is appropriately determined based on specifications required according to the shape of the lens 2 and the use of the optical sheet. For example, in the case of the lenticular lens array 11 of FIG. 3, it is formed in a predetermined region in a stripe shape parallel to the longitudinal direction of the cylindrical lens as shown in FIG. Further, in the case of the cross lenticular lens array of FIG. 4, as shown in FIG. 9 (a), each crossed cylindrical lens is provided in a stripe shape parallel to the longitudinal direction and has a predetermined area in a crossed grid shape. Formed. Note that the present invention is not limited to these, and the light reflecting portion 6 may be provided in a region including the non-light-condensing surface of the lens 2. As another example of FIG. 9A, the shape shown in FIG. It can be.

  The light reflecting portion 5 can be formed by forming a white reflective layer by coating a fine particle such as titanium dioxide, barium sulfate, or zinc oxide with a resin by a coating method, a printing method, a transfer method, or the like. Further, it can be formed by vapor deposition of metal such as Al or Ag which is silver, or a dielectric multilayer film.

  It is also possible to use an organic coloring material that develops color from colorless to white or a color close to white.

  The light reflecting portion 5 is arranged on the flat surface 4 as shown in FIG. 1 or inside the light transmissive member 7 or inside as shown in FIGS. 10 (a) and 10 (b). be able to.

  Further, as shown in FIG. 11, for the purpose of preventing the light emitted from the light source from passing through the light reflecting portion 6 and increasing the reflectance of light in the light reflecting portion 6 and the optical sheet, A vapor deposition part 18 made of a metal such as Al or Ag can also be provided on the back surface, that is, between the light reflection part 6 and the flat surface 4. Thereby, the light loss can be suppressed, and the backlight and the liquid crystal display device have a wide viewing angle with high brightness, low power consumption, and the same brightness.

  Next, as shown in FIG. 12, a protective layer 19 can be provided on the flat surface 4 including the light reflecting layer 6. The protective layer 19 is light-transmitting and excellent in physical properties such as wear resistance, solvent resistance, and heat resistance, and improves the abrasion resistance of the optical sheet 1 so that the optical sheet 1 in the backlight manufacturing process can be improved. The occurrence of defects such as surface damage can be reduced, yield can be increased, and cost can be reduced.

  Further, by providing the protective layer 19 with an ultraviolet ray absorbing action, the ultraviolet ray from the light source is absorbed by the protective layer 19, thereby reducing the ultraviolet ray transmitted through the optical sheet 1 and improving the light resistance of the optical sheet 1. In addition to protecting the observer, it is possible to extend the product life of the backlight using the optical sheet 1 and the liquid crystal display device.

  Furthermore, by providing the protective layer 19 with an ultraviolet absorbing function containing a fluorescent substance, it becomes possible to convert ultraviolet rays contained in light emitted from a cold cathode tube, which is one of the light sources, into visible light. The amount of light can be used effectively without increasing the light emitted from the light source. This results in high brightness and low power consumption.

  As shown in FIG. 13, an inflexible or small resin plate 20 made of a transparent resin can be laminated on the optical sheet 1. This resin plate 20 can be used as a support means for stabilizing the thin optical sheet 1. Alternatively, a filler can be mixed in the resin plate 20 to scatter light incident from the light source, and can be used as a diffusing means. The thickness of the resin plate 20 is 250 μm to 5 mm, and examples thereof include polycarbonate and polyethylene terephthalate.

  The resin plate 20 can be a multilayer of two or more layers within the above thickness range. For example, in the case of three layers, any one of the resin layers 21 to 21 as shown in FIGS. 23 can be mixed with a filler. Further, one or both of the outermost layers of the resin plate 20 or, in the case of multiple layers, either of the intermediate layer surfaces can be matted (roughened).

  FIG. 15 is a schematic cross-sectional view of a backlight 50 of the present invention using the optical sheet 1 described above, that is, a surface light source device.

  In the backlight 50 of the present invention, a plurality of (or one) linear light sources 48 such as a cold cathode tube, a hot cathode tube, and an LED are attached to a housing 9 having a reflection layer 10 provided on the inner surface thereof, and the upper surface thereof. The diffusing plate 24 and the optical sheet 1 are sequentially disposed.

  FIG. 16 is a schematic cross-sectional view of a liquid crystal display device 60 using the optical sheet 1 described above. The support substrates 25 and 26, which are transparent substrates, are provided above the backlight 50, that is, above the optical sheet 1, respectively. A liquid crystal panel 30 including polarizing plates 27 and 28 and a liquid crystal layer 29 sandwiched between them is provided outside. The support substrates 25 and 26 are an active matrix substrate and a counter substrate, and a thin film transistor (TFT) and a transparent pixel electrode are provided in a matrix on the liquid crystal layer 29 side of the active matrix substrate, and on the liquid crystal layer 29 side of the counter substrate. Are provided with a transparent electrode and a color filter.

The light emitted from the linear light source 48 passes through the diffusion plate 24 and the light transmission part 5 (opening), and the light incident on the light reflection part 6 is reflected and passes through the diffusion plate 24 to reflect the reflection layer 10 in the housing 9. The light is re-entered, reflected again, and repeatedly reflected until it passes through the light transmission part 5 (opening) and reused. The light emitted from the optical sheet 1 enters the liquid crystal panel 30, and the observer observes the image by modulating the intensity of the light through the liquid crystal panel 30.
A lens surface 3 having a lens 2 corresponding to the light transmission portion 5 (opening portion) is disposed. At this time, the diffusibility of the light emitted from the lens unit 3 is controlled according to the size of the light transmission unit 5 (opening) by positioning the light reflection unit 5 outside the focal plane of the lens surface 3. Is possible. When the lens surface 3 and the light reflecting portion 6 are arranged so as to form an image in the liquid crystal layer 29 of the liquid crystal panel 30 through the light transmitting portion 5 (opening portion), the light is condensed in the liquid crystal layer 29. By matching the arrangement of the lenses 2 with the pitch of the liquid crystal, the energy of light lost by the black matrix of the liquid crystal can be reduced, and light can be used more efficiently.

It is a schematic sectional drawing which shows one structural example of the optical sheet 1 of this invention. It is a schematic sectional drawing which shows the other structural example of the optical sheet 1 of this invention. 2 is a schematic cross-sectional view showing a configuration example of a lens 2. FIG. 2 is a schematic cross-sectional view showing a configuration example of a lens 2. FIG. 2 is a schematic cross-sectional view showing a configuration example of a lens 2. FIG. 2 is a schematic cross-sectional view showing a configuration example of a lens 2. FIG. (A)-(c) is a schematic sectional drawing which shows one structural example of the lens 2. FIG. It is the schematic which shows one structural example of the shape of the light reflection part. (A) And (b) is the schematic which shows one structural example of the shape of the light reflection part 5. FIG. (A) And (b) is a schematic sectional drawing which shows the other structural example of the optical sheet 1 of this invention. It is a schematic sectional drawing which shows the other structural example of the optical sheet 1 of this invention. It is a schematic sectional drawing which shows the other structural example of the optical sheet 1 of this invention. It is a schematic sectional drawing which shows the other structural example of the optical sheet 1 of this invention. (A)-(c) is a schematic sectional drawing which shows the other structural example of the optical sheet 1 of this invention. It is a schematic sectional drawing which shows one structural example of the backlight 50 of this invention. It is a schematic sectional drawing which shows the example of 1 structure of the liquid crystal display device 60 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical sheet 2 Lens 3 Lens surface 4 Flat surface 5 Light reflection part 6 Light transmission part 7 Light transmissive member 8 Base material sheet 9 Housing | casing 10 Reflective layer 11, 14 Lenticular lens array 12, 15, 16, 17 Cross lenticular array DESCRIPTION OF SYMBOLS 13 Micro lens array 18 Evaporating part 19 Protective layer 20 Resin plates 21, 22, 23 Resin layer 24 Diffusion plates 25, 26 Support substrates 27, 28 Polarizing plate 29 Liquid crystal layer 30 Liquid crystal panel 48 Linear light source 50 Backlight 60 Liquid crystal display device

Claims (25)

  A light transmissive member having a lens surface and a flat surface formed by arranging a plurality of lenses formed in a convex shape at a predetermined pitch, wherein the flat surface includes a non-light-collecting surface of the lens. An optical sheet comprising a light reflecting portion and a light transmitting portion in a region other than the light reflecting portion.   A light transmissive member having a lenticular lens surface and a flat surface in which a plurality of convex cylindrical lenses formed at a predetermined pitch are arranged in parallel, and the flat surface has a non-condensing portion of the cylindrical lens. An optical sheet comprising: a stripe-shaped light reflecting portion in a longitudinal direction in a region including a surface; and a light transmitting portion in a region other than the light reflecting portion.   The optical sheet according to claim 2, wherein a plurality of sets of cylindrical lenses of the lenticular lens arranged in parallel are arranged at intervals.   A light transmitting member having a cross lenticular lens surface and a flat surface in which a plurality of convex cylindrical lenses formed at a predetermined pitch are arranged in parallel in the vertical and horizontal directions so as to intersect on the same plane in the longitudinal direction. The optical sheet is characterized in that the flat surface is provided with a light reflecting portion in a region including a non-condensing surface of the cylindrical lens and a light transmitting portion in a region other than the light reflecting portion.   5. The set according to claim 4, wherein a plurality of sets in which a plurality of cylindrical lenses in any one of vertical and horizontal directions intersecting on the same plane of the cross lenticular lens are arranged in parallel are arranged at intervals. Optical sheet.   The optical sheet according to claim 4 or 5, wherein one of the cylindrical lens diameters in the vertical and horizontal directions intersecting on the same plane of the cross lenticular lens is larger than the diameter of the other cylindrical lens.   7. The optical sheet according to claim 4, wherein the light transmission part is included in a region where the cylindrical lens of the cross lenticular lens intersects in the vertical and horizontal directions.   A light transmissive member having a microlens array having a plurality of fine convex microlenses and a flat surface, wherein the flat surface has a light reflecting portion in a region including a non-light condensing surface of the microlens, An optical sheet comprising a light transmission part in a region other than the light reflection part.   The optical sheet according to claim 1, wherein the light transmissive member has a lens portion formed on a light transmissive substrate.   The optical sheet according to claim 1, wherein the light transmission part is an opening of the light reflection part.   The optical sheet according to claim 1, wherein a vapor deposition part is provided between the light reflection part and the flat surface.   The optical sheet according to any one of claims 1 to 8, wherein the reflecting portion is located inside the light-transmitting member from a flat surface.   The optical sheet according to claim 1, wherein a protective layer is formed on the light reflection member and the light transmissive member including the light reflection portion.   The optical sheet according to claim 1, wherein the protective layer has an ultraviolet absorbing function.   The optical sheet according to claim 1, wherein the protective layer includes a fluorescent material.   16. An optical sheet obtained by laminating an inflexible resin sheet on the optical sheet according to claim 1.   The optical sheet according to claim 16, wherein a filler is mixed into the resin sheet.   The optical sheet according to claim 16, wherein the resin sheet is composed of multiple layers, and fillers are mixed in all or a part of the layers.   The optical sheet according to any one of claims 16 to 18, wherein the resin sheet is composed of multiple layers, and the surface of all or a part of the layers is subjected to a mat treatment. One or more linear light source devices;
A reflecting surface and a reflecting portion in a region including a lens surface and a flat surface in which a plurality of lenses formed in a convex shape at a predetermined pitch are arranged, and the flat surface includes a non-condensing surface of the lens. An optical sheet provided with a light transmission part in a region other than
, And the irradiation light from the linear light source device is emitted through the light transmission part.   The backlight according to claim 20, wherein the optical sheet is the optical sheet according to claim 2.   The backlight according to claim 20 or 21, wherein a linear light source of the linear light source device and a cylindrical lens formed in a longitudinal direction of the optical sheet have a parallel or an angle. One or more linear light source devices;
A reflecting surface and a region other than the reflecting portion in a region including a non-light-condensing surface of the lens, the lens surface having a plurality of lenses formed in a convex shape at a predetermined pitch and a flat surface; An optical sheet provided with a light transmitting portion,
LCD panel,
A liquid crystal display device comprising a color filter and an irradiation light emitted from the linear light source device through the light transmission portion toward the liquid crystal panel.   The liquid crystal display device according to claim 23, wherein the optical sheet is an optical sheet according to claim 2.   The liquid crystal display device according to claim 23 or 24, wherein a linear light source of the linear light source device and a cylindrical lens formed in a longitudinal direction of the optical sheet have a parallel or an angle.