JP5104459B2 - Optical member and backlight unit and display using it - Google Patents

Description

  The present invention illuminates, from the back side, a liquid crystal panel in which a transmissive / non-transmissive lens sheet and a display optical sheet in pixel units or a display element in which a display pattern is defined according to a transparent state / scattering state is arranged. The present invention relates to a backlight unit and a display device.

  In recent years, liquid crystal display devices using TFT liquid crystal panels and STN liquid crystal panels have been commercialized mainly for color notebook PCs (personal computers) in the OA field.

  In such a liquid crystal display device, a so-called backlight method in which a light source is arranged on the back side (observer side) of the liquid crystal panel and the liquid crystal panel is illuminated with light from the light source is employed.

  As a backlight unit employed in this type of backlight system, a light source lamp such as a cold cathode fluorescent lamp (CCFT) is roughly divided into a flat light guide plate made of acrylic resin having excellent light transmittance. There are a “light guide plate light guide method” for reflecting (a so-called edge light method) and a “direct type method” that does not use a light guide plate.

  As a liquid crystal display device on which a light guide plate light guide type backlight unit is mounted, for example, the one shown in FIG. 12 is generally known.

  This is provided with a liquid crystal panel 72 sandwiched between polarizing plates 71 and 73 at the top, and a light guide plate 79 made of a transparent base material such as a substantially rectangular plate-like PMMA (polymethyl methacrylate) or acrylic on the lower surface side. Is installed, and a diffusion film (diffusion layer) 78 is provided on the upper surface (light emission side) of the light guide plate.

  Further, a scattering reflection pattern portion for efficiently scattering and reflecting the light introduced into the light guide plate 79 in the direction of the liquid crystal panel 72 is provided on the lower surface of the light guide plate 79 by printing or the like. A reflection film (reflection layer) 77 is provided below the scattering reflection pattern portion (not shown).

Further, the light guide plate 79 is provided with a light source lamp 76 at the side end, and further covers the back side of the light source lamp 76 so that the light from the light source lamp 76 can be efficiently incident on the light guide plate 79. Thus, a high-reflectance lamp reflector 81 is provided. The scattering reflection pattern portion is formed by printing, drying, and forming a mixture of white titanium dioxide (TiO ₂ ) powder in a solution such as a transparent adhesive in a predetermined pattern, for example, a dot pattern. The light incident on the light plate 79 is imparted with directivity and guided to the light exit surface side, which is a device for increasing the brightness.

  Furthermore, recently, in order to increase the light utilization efficiency and increase the brightness, as shown in FIG. 13, a prism film (prism layer) having a light condensing function between the diffusion film 78 and the liquid crystal panel 72 is used. ) 74 and 75 are proposed. The prism films 74 and 75 are configured to collect light emitted from the light exit surface of the light guide plate 79 and diffused by the diffusion film 78 on the effective display area of the liquid crystal panel 72 with high efficiency.

However, in the apparatus illustrated in FIG. 12, the control of the viewing angle is entrusted only to the diffusibility of the diffusion film 78, which is difficult to control, and the center in the front direction of the display is bright and becomes darker toward the periphery. This characteristic is inevitable. For this reason, when the liquid crystal screen is viewed from the side, the luminance is greatly reduced, and the light utilization efficiency is reduced.
Furthermore, in the apparatus using the prism film illustrated in FIG. 13, two prism films are required, which not only greatly reduces the amount of light due to the absorption of the film but also increases the cost due to the increase in the number of members. It was also.

  On the other hand, in the direct type, a display device such as a large liquid crystal TV in which the light guide plate is difficult to use is used.

  As a direct type liquid crystal display device, a device illustrated in FIG. 14 is generally known. In this, a liquid crystal panel 72 sandwiched between polarizing plates 71 and 73 is provided on the upper side, and is emitted from a light source 51 made of a fluorescent tube or the like on the lower surface side thereof and diffused by an optical sheet such as a diffusion film 82. The light is condensed on the effective display area of the liquid crystal panel 72 with high efficiency. In order to efficiently use the light from the light source 51 as illumination light, a reflector 52 is disposed on the back surface of the light source 51.

However, even in the apparatus illustrated in FIG. 14, the control of the viewing angle is left only to the diffusibility of the diffusion film 82, which is difficult to control, and the center portion in the front direction of the display is bright and becomes darker toward the peripheral portion. This characteristic is inevitable. For this reason, when the liquid crystal screen is viewed from the side, the luminance is greatly reduced, and the light utilization efficiency is reduced. Furthermore, in the case of using a prism film, since the number of prism films is two, not only the light amount is greatly decreased due to absorption of the film but also the cost is increased due to an increase in the number of members.

If the distance between the light sources 51 is too wide, uneven brightness tends to occur on the screen, and the number of light sources 51 cannot be reduced, leading to an increase in power consumption and an increase in cost.

By the way, in such a liquid crystal display device, light weight, low power consumption, high luminance, and thinning are strongly demanded as market needs, and accordingly, a backlight unit mounted on the liquid crystal display device is also light. In addition, low power consumption and high brightness are required.

In particular, in a color liquid crystal display device that has recently made remarkable progress, the panel transmittance of the liquid crystal panel is remarkably lower than that of a monochrome-compatible liquid crystal panel. It is essential to obtain power consumption.

However, as described above, it is difficult to say that the conventional apparatus sufficiently satisfies the demand for high luminance and low power consumption, and the user has low price, high luminance, high display quality, and low power consumption. The development of a backlight unit capable of realizing a power liquid crystal display device is awaited.

In view of the above situation, for example, as disclosed in Patent Document 1, the present applicant includes a liquid crystal panel and light source means for illuminating light from the back side of the liquid crystal panel, and the light source means includes light from the light source. A liquid crystal display device has been proposed in which a lens layer for guiding the liquid crystal panel to the liquid crystal panel is provided and a light-shielding portion having an opening in the vicinity of the focal plane of the lens layer.

In the above-mentioned Patent Document 1, as shown in FIGS. 1 to 3 of the same document, a configuration in which a lens sheet having a light-shielding portion is disposed between a liquid crystal panel and a backlight unit is disclosed. 1 to 3, the lens sheet has a concavo-convex shape constituting a lens portion on the liquid crystal panel side.

The effect obtained by interposing the lens sheet described above has a concavo-convex shape that forms a lens portion on the liquid crystal panel side by modulating the diffusivity of light emitted from the light guide plate by the lens action.

The effect obtained by interposing the lens sheet described above is that the diffusibility of the light emitted from the light guide plate can be modulated into the lens action, and the liquid crystal panel can be emitted in the same direction. .

In addition, by forming an opening at a specific location, it is possible to selectively increase the amount of light incident on the pixels of the liquid crystal panel, improving the use efficiency of the backlight and controlling the shape of the opening. In this way, it is possible to control the visual field region of the display light.
JP 2000-284268 A JP 2006-106197 A

FIGS. 11A and 11B are schematic views showing a typical configuration of a conventional integrated optical member. The first optical layer 1 and the second optical layer 5 are bonded via the fixing element 3 and the adhesive / adhesive 4. Since there is the fixing element 3, a gap 2 is obtained between the first optical layer 1 and the second optical layer 5. The fixing element 3 is provided in the first optical layer 1 or the second optical layer 5. The optical layer that does not have the fixing element 3 is in contact with the adhesive / adhesive 4 over the entire surface, but the bonding area between the fixing element 3 and the adhesive / adhesive 4 is the same as that of the optical layer that does not have the fixing element 3. -Less than the bonding area with the adhesive 4, and the individual bonding area is also small. In general, the adhesive force of the adhesive / adhesive is extremely reduced due to the reduction of the joint area, so that the joint interface between the fixing element 3 and the adhesive / adhesive 4 is very easy to peel off. It does not have an adhesive strength that can withstand In addition, since the fixing element 3 causes a decrease in the light collecting function, the bonding area is small and a smaller one is preferable.

In an optical member in which a lens sheet and a diffusion plate are integrated, in order to obtain a light condensing function, it is necessary to join with a diffusion plate of the lens sheet via a gap. In addition, an adhesive / adhesive is used as a joining method. Furthermore, a method of providing a fixing element between the lens sheet and the diffusion plate as shown in FIG.
However, in this case, since the bonding area between the fixing element and the adhesive / adhesive layer is small, the adhesion is extremely low. For this reason, there exists a problem that a lens sheet and a diffuser plate will peel easily by the temperature change and impact of lighting of a backlight. Further, there is a problem that the optical properties are deteriorated when the adhesive / adhesive layer sticks to the side surface of the fixing element.

The invention according to claim 1 is used for controlling an illumination optical path for a display, and includes a first optical layer and a second optical layer, and one of the first optical layer and the second optical layer. And an optical member in which the entrance surface of the first optical layer and the exit surface of the second optical layer are partially integrated via an adhesive / adhesive layer, An optical member having the fixing element in a first optical layer, wherein the adhesive / adhesive layer is a top portion of the adjacent fixing element at a location where the distance between the adjacent fixing elements is 250 μm or less. And an optical member in contact with only the exit surface of the second optical layer.
The invention of claim 2 is used for controlling an illumination optical path for a display, and includes a first optical layer and a second optical layer, and one of the first optical layer and the second optical layer. And an optical member in which the entrance surface of the first optical layer and the exit surface of the second optical layer are partially integrated via an adhesive / adhesive layer, An optical member having the fixing element in a second optical layer, wherein the adhesive / adhesive layer is a top portion of the adjacent fixing element at a location where the distance between the adjacent fixing elements is 250 μm or less. And an optical member in contact with only the incident surface of the first optical layer.
The invention of claim 3 is characterized in that the area of the fixed element is 1% or more and 50% or less of the total area of the incident surface of the first optical layer or the exit surface of the second optical layer. The optical member according to claim 1 or 2.
According to a fourth aspect of the present invention, in the optical member according to any one of the first to third aspects, the thickness of the adhesive / adhesive layer is within 1 times the height of the fixing element. is there.
A fifth aspect of the present invention is the optical member according to any one of the first to fourth aspects, wherein the adhesive / adhesive layer is not in contact with a side surface portion of the fixing element.
A sixth aspect of the present invention is the optical member according to any one of the first to fifth aspects, wherein a shielding layer is provided on a surface of the fixing element.
In the invention according to claim 7, the adhesive / adhesive layer has a storage elastic modulus of 0.1 to 0.5 (Mpa / 25 ° C.) and a loss elastic modulus of 0.1 to 0.4 (Mpa / 25). The optical member according to any one of claims 1 to 6, wherein the optical member has a temperature of ° C.
According to an eighth aspect of the present invention, there is provided a display backlight, comprising at least a light source and the optical member according to any one of the first to seventh aspects on a back surface of an image display element that defines a display image. Is a unit.
The invention of claim 9 comprises an image display element comprising a liquid crystal display element that defines a display image in accordance with transmission / shielding in pixel units, a light source, and the backlight unit according to claim 8. It is a display.

  In the present invention, it is possible to obtain an optical member having excellent adhesion and optical characteristics while being an integrated optical member that is functionally integrated as compared with a conventional optical sheet having a laminated structure that is not integrated. That is, greater adhesion can be obtained by providing the bonding surface of the adhesive / adhesive layer in the first optical layer and the second optical layer, respectively. Moreover, it is possible to obtain an optical member having excellent optical characteristics by not bonding the adhesive / adhesive layer to the side surface of the fixing element.

Embodiments of the present invention will be described below.

FIG. 1 shows a configuration example of a display using the integrated optical member of the present invention. The light K from the light source 15 enters the second optical layer 5 of the optical member 10. Thereafter, the gap 2, the fixing element 3, and the adhesive / adhesive 4 are transmitted or reflected from the emission surface of the second optical layer 5, and finally reach the incident surface of the first optical layer 1. Then, it is emitted as light L from the emission surface of the first optical layer 1.
Here, an optical member other than the optical member 10 such as a diffusion film can be used in the backlight.
Next, after the light L is emitted from the optical member 10, the light L passes through the diffusion sheet 13 and reaches the liquid crystal layer 19 sandwiched between the polarizing plates 21. The light transmitted here exits from S and is visually recognized by an observer.

The display device according to the embodiment of the present invention is a device that includes the light source 15 and the optical member 10 described above, and further includes a liquid crystal layer 19 thereon. In this case, the display device is a liquid crystal display device. However, the display device is not limited thereto, and includes a display device that displays an image using light, such as a projection screen device, a plasma display, and an EL display. If so, it doesn't matter.

  Further, for example, in FIG. 1, the optical member 10 has a second optical layer and a first optical layer formed in order on the light source 15, but the optical member 10 is placed opposite to the light source. However, the first optical layer and the second optical layer may be sequentially disposed on the light source 15. In this case, the optical member 10 condenses and diffuses the light from the light source 15 with a lens or the like formed in the first optical layer, and the light emitted from the first optical layer is transmitted through the second optical layer. Since the lamp image of the light source 15 can be erased by being further diffused, it is particularly effective when used, for example, when the luminance of the light source 15 is extremely high or when the installation interval between the light source and the liquid crystal panel is short.

The light source 15 supplies light used for image display on the display shown in FIG.

Here, examples of the light source 15 used in the present invention include the following. The light source 15 is preferably a CCFL or an LED with good luminous efficiency.
In FIG. 2A, a blue LED element 50 that emits blue light used in a mobile device such as a cellular phone is covered with a phosphor 51 that emits yellow light applied inside the LED lens 53 to make it pseudo white. The white LED 46 emits light.
This method has an advantage that pseudo white light emission can be realized simply by covering the phosphor with a single-color LED element. In addition, the light source 1 used in the present invention is not limited to the above-described one, and may be one in which one single-color LED element is covered with at least one kind of phosphor.

Next, FIG.2 (b) adds the prism shape to the lens 53 for LED of Fig.3 (a). By using the prism, the light distribution of the light emitted from the white LED 46 can be adjusted.

FIG. 2C shows a case where a plurality of white LEDs 46 are installed. By installing a plurality of white LEDs 46, the luminance is improved as compared with the case where one white LED 46 is used. Further, the size of the light guide plate 7 can be increased as compared with the case where one white LED 46 is used.
Furthermore, by efficiently installing a plurality of white LEDs 46, the efficiency is increased in the vicinity of the tops of the regular polygons of the light emitting surface 11 having the longest distance from the light source 1 compared to the case where the white LEDs 46 are installed alone. It becomes possible to guide light well.
Therefore, the relative light amount difference between the vicinity of each apex of the regular polygon of the above-described light exit surface 11 that is the region with the least amount of light and the vicinity of the center of the light exit surface 11 that is the region with the most light amount is reduced. Therefore, luminance unevenness can be reduced.

FIG. 3 shows a method of emitting pseudo white light by combining LED devices (red LED element 48, green LED element 49, and blue LED element 50) that emit light of a single color as another method of LEDs emitting pseudo white light. In this case, as compared with the case of FIG. A as described above, the problem that the phosphor 51 deteriorates due to heat generated from the LED elements can be avoided, and an arbitrary color can be obtained by adjusting the light quantity of each LED element. Can do.

FIG. 4 shows a combination of single color LEDs (red LED 54, green LED 55, blue LED 56) that emit light in a single color. In this case, the red LED 54, the green LED 55, and the blue LED 56 may be combined one by one as shown in FIG. 4B, or a plurality of colors with weak light output (for example, the green LED 55) may be used as shown in FIG. You may arrange and install.

The light source 1 is not limited to the above-described LED. For example, as shown in FIG. 5, the light of a monochromatic semiconductor laser (red semiconductor laser 57, green semiconductor laser 58, blue semiconductor laser 59) is mixed through a fiber 60 and emitted from a semiconductor laser lens 61. Also good.

The light K incident from the light source 15 enters the second optical layer 5. The light incident on the second optical layer 5 is scattered inside and emitted as diffused light.
Here, the second optical layer 5 can be a diffusion sheet, a diffusion plate or the like imparted with diffusibility by an additive in the layer. Here, fine irregularities and lenses may be formed on the surface of the second optical layer 5. That is, an optical layer having a diffusion function can be used depending on the difference in surface shape and refractive index of the material.

Here, when the second optical layer 5 is a diffusion plate, the following materials are used.
For example, PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate), PMMA (polymethyl methacrylate), benzyl methacrylate and MS resin, PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate), acrylonitrile polystyrene Flat plate made of optically transparent resin such as polymer, PMMA (polymethyl methacrylate), benzyl methacrylate, MS resin, other acrylic resin, COP (cycloolefin polymer), AS (acrylonitrile polystyrene copolymer) It is formed by imparting light diffusibility to the shaped member. The method is not particularly limited. For example, the surface of the flat plate member is subjected to surface roughening by fine unevenness processing or polishing (hereinafter, the surface on which these are applied is referred to as “sand-rubbed surface”) to impart diffusibility. Or pigments such as silica, titanium oxide, and zinc oxide that scatter light on the surface, or beads such as resin, glass, zirconia, etc., together with a binder, or the above-mentioned pigments and beads that scatter light into the above resin It is formed by kneading a kind.

Moreover, the resin sheet which formed the void by kneading and extending | stretching a filler in PET, PP (polypropylene), etc., and raised the diffusivity may be sufficient.
In the present invention, as the diffusion plate, it is preferable to use a member having a thickness of 0.01 mm or more and 5.0 mm or less to which the above-described material is used and which imparts light diffusibility.
When rigidity is required for the diffusion plate, a diffusion plate having a thickness of 1.0 mm or more and 5.0 mm or less is preferable. When flexibility is required for the diffusion plate, a diffusion sheet having a thickness of 0.01 mm or more and 1.0 mm or less is preferable.
Furthermore, the surface of the diffusion plate may be formed with a concavo-convex shape or a mat shape. Thereby, the uniformity of the light emitted from the diffusion plate can be further improved. In this case, the concavo-convex shape is preferably a prism shape or a lens shape having a center line average roughness Ra of 3 μm to 1,000 μm. In the case of the prism shape, the prism shape is preferably polygonal, the prism apex angle is preferably 40 ° to 170 °, and the prism pitch is preferably 20 μm to 700 μm. The prism shape may be a pyramid shape or a truncated pyramid shape. The uneven shape described above may change its shape according to the illuminance or brightness of light incident on the uneven shape. For example, in the region where the illuminance or brightness of light incident on the uneven shape is large, the prism tops described above may be used. The corner may be increased.
Furthermore, the total light transmittance of the diffusion plate in this case is preferably 40% or more and 98% or less, the haze is preferably 20% to 100%, and the water absorption is preferably 0.25% or less.

Moreover, it is preferable to have transparent particles dispersed in the main material, and the refractive index of these main materials and the refractive index of the transparent particles are different. The difference between the refractive index of the main material and the refractive index of the transparent particles is preferably 0.01 or more. If the difference in refractive index is smaller than this, sufficient light scattering performance cannot be obtained. Further, the refractive index difference is 0.5 or less. The transparent particles preferably have an average particle size of 0.5 to 10.0 μm.

Moreover, as transparent particles, transparent particles made of inorganic oxide or transparent particles made of resin can be used. For example, examples of the transparent particles made of an inorganic oxide include particles made of silica, alumina or the like. The transparent particles made of resin include acrylic particles, styrene particles, styrene acrylic particles and crosslinked melamine-formalin condensate particles, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoro). Examples thereof include fluorine-containing polymer particles such as ethylene-hexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene-tetrafluoroethylene copolymer), and silicone resin particles. These transparent particles may be used as a mixture of two or more. Alternatively, the plate-like member has a structure in which a main material has a fine cavity containing air, and diffusion performance may be obtained by a difference in refractive index between the main material and air.

The second optical layer 5 may have a multilayer structure, and the multilayer structure may include a transparent resin layer that does not include transparent particles or the like.

The second optical layer 5 described above is manufactured by a casting method or an injection method.

The diffused light emitted from the second optical layer 5 described above is incident on the first optical layer 1.

Here, the first optical layer 1 is not particularly limited as long as desired light refraction, transmission, reflection, and polarization can be obtained. A specific example is shown in FIG.
FIG. 6A shows a polarization separation / reflection sheet. The light utilization efficiency can be increased by transmitting only light in a specific polarization state and separating and reflecting light in other polarization states.
FIG. 6B shows a prism sheet having a prism structure on a base material. The prism structure can retroreflect light in the front direction and increase the light utilization efficiency.
FIG. 6C shows a prism sheet having a curved surface at the apex. Wear physical properties can be improved by forming a curved surface at the apex of the prism.
FIG. 6D shows a sheet formed with a wave-shaped structure. Moire can be reduced because the shape is such that the boundary line is not generated along with the collection of light.
FIG. 6E shows a lenticular lens sheet. Compared to FIG. 6B, side lobes can be reduced.
FIG. 6F shows a lens sheet having an asymmetric cross-sectional shape. For example, a cross-sectional shape in which one side is formed in a linear shape and the other is formed in a convex curved shape on the outside, and the above-described linear shape and the curved shape are rounded and connected at the lens apex portion. In this case, the light distribution can be changed asymmetrically.
FIG. 6G shows a lens sheet in which the lens height or lens pitch is random. In this case, moire can be reduced. Random height or pitch may be applied to the prism sheet.
FIG. 6 (h) shows a double-sided lens sheet in which lenses are molded on both the back side and the viewer side. Condensing efficiency can be improved by attaching lenses to both sides.
FIG. 6I shows a double-sided lens sheet which is a double-sided lens sheet and one lens is a plurality of lenses on one side. Condensing efficiency can be improved by using a plurality of lenses on one side.
FIG. 6J shows an inverted V-shaped recess formed on the top of the lenticular lens sheet. By forming the recesses, retroreflection can be performed to improve the light utilization efficiency.

In FIG. 6, a prism sheet, a lenticular lens sheet, or the like is used, but a sheet in which optical elements similar to prisms are regularly arranged may be used instead. In addition, a sheet that regularly includes an optical element such as a concave lens, a convex lens, and a pyramid type that has a lens effect can be used instead of the prism sheet.

As long as the material of the first optical layer 1 has transparency, heat resistance, mechanical strength, solvent resistance to withstand manufacturing, and the like, various materials can be applied depending on applications. For example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate-isophthalate copolymer, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, polyethylene terephthalate / polyethylene naphthalate Polyester resins such as coextruded films, polyamide resins such as nylon 6, nylon 66 and nylon 610, polyolefin resins such as polyethylene, polypropylene and polymethylpentene, vinyl resins such as polyvinyl chloride, polyacrylates and polymetas Acrylic resins such as acrylate and polymethylmethacrylate, imide resins such as polyimide, polyamideimide, and polyetherimide, polyarylate, and polysulfone Engineering resins such as polyethersulfone, polyphenylene ether, polyphenylene sulfide (PPS), polyaramide, polyetherketone, polyethernitrile, polyetheretherketone, polyethersulfite, polycarbonate, polystyrene, high impact polystyrene, acrylonitrile polystyrene There are styrene resins such as coalescence, ABS resin, cellophane, cellulose triacetate, cellulose diacetate, cellulose films such as nitrocellulose, etc.

Further, in the case of a polarized light separating / reflecting sheet, the first optical layer 1 may be manufactured by stretching a multi-layered film in which two types of layers having different refractive indexes are alternately stacked in a single axis direction. Good.
In the case of a prism sheet, a lens sheet, etc., it is formed by an extrusion molding method, an emission molding method, a casting method, or a hot press molding method well known in the art. In this case, the base material and the lens portion may be composed of one base material made of the same material, or may be made from different base materials of different materials. In addition, a step may be provided on the non-light-condensing part on the opposite side of the lens part to mold the part. Moreover, although thickness can be used at 12 micrometers or more and 2 mm, 12 micrometers or more and 500 micrometers or less are especially preferable.
The lens portion may be molded using UV or radiation curable resin (the type is not particularly limited as long as the resin includes a material curable by UV or radiation).

The first optical layer 1 can be made of the same main material as that of the second optical layer 5 and may be configured to include the transparent particles described above. The refractive index of these main materials and the refractive index of transparent particles need to be different. The difference between the refractive index of the main material and the refractive index of the transparent particles is preferably 0.02 or more. If the difference in refractive index is smaller than this, sufficient light scattering performance cannot be obtained. Further, the refractive index difference may be 0.5 or less. In addition, since the light incident on the optical layer needs to be transmitted while being scattered, the average particle size of the transparent particles is preferably 0.5 to 10.0 μm. Alternatively, the main material may have a structure having fine cavities containing air, and the diffusion performance may be obtained by the difference in refractive index between the main material and air.

Or the 1st optical layer 1 may apply | coat the fine particle layer to the surface of the one side or both surfaces of the above-mentioned base material. Examples of the fine particle layer include transparent ink containing beads, spacers, and the like, but the thickness of the fine particle layer, the type and size of the fine particles are not limited.

The first optical layer 1 and the second optical layer 5 described above are integrated by the adhesive / adhesive layer 4 via the fixing element 3.

(A), (b) of FIG. 7 is a figure which shows the structural example of the optical member of this invention.
FIG. 7A shows a configuration example in which the first optical layer 1 includes a fixing element 3. FIG. 7B shows a configuration example in which the second optical layer 5 includes the fixing element 3.
In this case, the light source 15 is located on the side opposite to the first optical layer 1 with respect to the second optical layer 5. In the present invention, the adhesive / adhesive layer 4 is in contact with the entrance surface of the first optical layer 1 and the exit surface of the second optical layer 5. Further, in order to maintain the gap 2, the adhesive / adhesive layer 4 is partially in contact with the entrance surface of the first optical layer 1 or the exit surface of the second optical layer 5.
For this reason, compared with the case where the adhesive / adhesive layer 4 is in contact only with the fixing element 3 as in the conventional configuration, the adhesive / adhesive layer 4 is not only the fixing element but also the incidence of the optical layer having the fixing element or Since it is also joined to the emission surface, the joining area is larger than that of the conventional configuration, and strong adhesion as shown in the examples described later can be obtained.

Incidentally, in FIGS. 8A and 8B, the adhesive / adhesive layer 4 is in contact with the side surface of the fixing element, and in this case, the effect of the first optical layer 1 cannot be sufficiently obtained.

10 (a), when the adhesive / adhesive layer 4 is in contact with the side surface of the fixing element 3, the difference in refractive index between the fixing element 3 and the adhesive / adhesive layer 4 is small, so that the diffused light is not viscous. When propagating from the adhesive layer 4 to the fixing element, it is hardly refracted and propagates in the fixing element 3 as diffused light. At this time, part of the diffused light (light ray A) is incident on the optical layer 1 with a large angle with respect to the S direction. When the light is incident with a large angle with respect to the S direction, the optical layer 1 is not deflected in the S direction and becomes stray light.
On the other hand, when the adhesive / adhesive layer 4 is not in contact with the side surface of the fixing element as shown in FIG. 10B, the difference in refractive index between the fixing element 3 and the gap 2 is sufficiently large. Is incident on the angle φ. The condensed light is emitted from the fixed element 3 to the gap 2 at a position facing the incident position. For this reason, since it does not enter the first optical layer 1 with a large angle with respect to the S direction, stray light is not generated and the light use efficiency does not decrease.

Here, from FIG. 9, the side surface of the fixing element 3 refers to the height of the fixing element 3 from the light incident surface of the first optical layer 1 or the light emitting surface of the second optical layer 5 on which the fixing element is installed. The height up to 30% with respect to the height H.
Further, the top of the fixing element 3 is a portion to be joined to the adhesive / adhesive layer 4 and may be buried to a height of 5% to 70% with respect to the height H of the fixing element.
Further, when the adhesive / adhesive layer 4 is bonded to the side surface of the fixing element 3 in 60% or more of the total number of the fixing elements 3, the optical characteristics are not particularly good.

Examples of the adhesive / adhesive layer 4 include acrylic, urethane, rubber, and silicone adhesives / adhesives. In order to ensure a stable gap, transparent fine particles such as beads may be mixed in the contact / adhesive layer 4.
Depending on circumstances, the adhesive / adhesive layer 4 may be a double-sided tape or a single layer.

Furthermore, since the contact / adhesive is used in the display area, the light absorption must be within 1%. If it exceeds 1%, the integrated light quantity emitted from the optical member 10 decreases, and the front luminance decreases regardless of the optical layer. Further, the thickness of the adhesive / adhesive layer 4 must be within 1 times the height of the fixing element 3. When it exceeds 1 time, the adhesive / adhesive layer 4 fills the fixing element 3, and the gap cannot be maintained. In addition, although it becomes the tendency which is hard to be buried by increasing the degree of crosslinking of a sticky / adhesive and making it hard, the adhesive force of a sticky / adhesive falls. Although there is a composition that keeps the gap even when the thickness exceeds 1 time of the optical element, the degree of cross-linking is too high, so there is no adhesion that can withstand practical use.

Further, as shown in FIG. 7, the adhesive / adhesive layer 4 does not adhere to the side surface of the fixing element 3 and must not completely fill the fixing element 3, and therefore has the following characteristics. The adhesive / adhesive layer 4 has a storage elastic modulus of 0.1 to 0.5 Mpa at 20 ° C., and a loss elastic modulus of 0.1 to 0.4 Mpa at 20 ° C.
That is, when the storage elastic modulus is 0.1 MPa or less, the adhesive / adhesive layer 4 sticks to the side surface portion of the fixing element 3, and when the storage elastic modulus is 0.5 MPa or more, the first optical layer 1 and the second optical layer 5 are in close contact with each other. Sexuality gets worse. When the loss elastic modulus is 0.1 MPa or less, the adhesive / adhesive layer 4 is attached to the side surface portion of the fixing element 3, and when the loss elastic modulus is 0.4 MPa or more, the first optical layer 1 and the second optical layer 5 Adhesion is poor.

The method of providing the adhesive / adhesive layer 4 may be various coating apparatuses such as a comma coater, a printing method, a method using a dispenser or spray, or a manual coating using a brush or the like. Alternatively, a method may be used in which a dry film of an adhesive / adhesive is prepared in advance using these methods, and the dry film is bonded to the optical layer.

Next, the fixing element 3 secures a gap between the first optical layer 1 and the second optical layer 5. By using the fixing element 3, the air layer can be fixed uniformly with a constant thickness, so that appearance characteristics such as optical adhesion, unevenness, and Newton ring can be improved. The fixing element 3 is composed of a main material molded into a certain shape.

Examples of the main material of the fixing element 3 include polyester resin, acrylic resin, polycarbonate resin, polystyrene resin, acrylic / styrene copolymer, polymethylpentene resin, styrene / butadiene / acrylonitrile copolymer, and cycloolefin polymer. Main materials such as thermoplastic resins such as polyester acrylate, urethane acrylate, epoxy acrylate and other radiation curable resins are generally used, but in addition to the above materials, the fixing element 3 Resins that can exhibit these characteristics can also be used.

In addition, the main material may contain other effects such as diffusion and coloring by containing inorganic and organic particles and bubbles. As particles dispersed in the main material, silica, alumina, titanium oxide, carbon black, inorganic materials such as glass beads, and organic materials such as various resin beads can be used. Various particles dispersed in the transparent fixing element 3 can be locally arranged, for example, by giving the surface of the fixing element 3 a reflection characteristic. Further, bubbles can be dispersed in the resin and used instead of the particles. These particles and bubbles dispersed in the main material may be used in combination of a plurality of types or may not be used depending on the intended use.

The fixing element 3 may be integrally formed with the first optical layer 1 or the second optical layer 5. In this case, the material may be the same as each optical layer, or the ratio of the material and additives such as particles may be changed in the vicinity of the fixed element 3. Alternatively, the fixing element 3 may not be integrally formed with another optical layer.

As for the height of the fixing element 3, it is necessary to maintain a gap of 200 nm or more in order to prevent optical adhesion due to distortion of a non-rigid sheet-like member and to obtain a refractive index difference. On the other hand, when the height of the fixing element 3 exceeds 2 mm, the visibility of the fixing element 3 is increased, causing unevenness, and light leakage is liable to occur from the side.

An increase in the bonding area of the fixing element 3 causes a decrease in luminance. Therefore, the bonding area is set to 1% to 50% of the area of the first optical layer 1 or the second optical layer 5. If it is less than 1%, it is practically impossible to obtain adhesion that can withstand practical use regardless of the present invention, and if it exceeds 50%, the luminance is too low to perform the function as the original optical member 10.

In addition, as the shape of the fixing element 3, a linear structure such as a lenticular shape, a trapezoidal shape, and a prism shape extending in one direction, a polygonal cone, a cone (or a truncated cone, a truncated cone, etc.), a polygonal column, a columnar column such as a cylinder, a rectangular parallelepiped Or a point structure such as a sphere (or hemisphere) or an ellipsoid. Alternatively, a lattice shape or a combination of these shapes may be used. If the height of the fixing element 3 is constant, the shape of the side surface may be an unspecified shape or may be stepped. When securing a space | gap with these fixed elements 3, you may use said 1 type of fixed element 3 structure for the whole, or may use it combining several types of fixed element 3 structure. The arrangement of the fixing elements 3 may be periodic or random such as a stripe shape or a dotted line, and is appropriately selected according to the design.

In addition, the ground contact area of one fixed element 3 is related to a line structure such as a lenticular shape, a trapezoidal shape, and a prism shape extending in one direction in order to reduce the visibility of unevenness of the fixed element 3 during image display. The line width is preferably 200 μm or less. In addition, it is preferable that the ground contact area of a point structure such as a cone (or a truncated cone, a truncated cone or the like), a polygonal column, a cylinder, or a point structure such as a rectangular parallelepiped, a sphere (or hemisphere), or an ellipsoid is 35000 μm 2 or less.
In order to further improve the visibility, it is more preferable that the line width is 50 μm and the area is 8000 μm 2 or less.

Next, the surface of the fixing element 3 may have a shielding surface that shields light. Since the light is shielded, the light may be reflected, and a black layer that absorbs light, such as carbon black, may be provided on the surface of the fixing element 3.

The case where the fixing element 3 having a plurality of reflecting surfaces is used will be described.

In the case of the fixing element 3 having a reflective surface, it can be prepared by mixing metal particles or high refractive index transparent particles into the main material forming the fixing element 3. Further, a highly light-reflective metal such as silver, aluminum, or nickel can be formed on the surface of the fixing element 3 by dry film formation such as vapor deposition or sputtering.

Alternatively, it can also be produced by applying an ink obtained by dispersing and mixing high refractive index transparent particles on the surface of the transparent fixing element 3. In addition to the method described above, as a method for forming a reflective layer, it is possible to form a material in which metal particles or high refractive index transparent particles are kneaded in a binder, or to form a laminate of white foil or metal foil.

Here, examples of the high refractive index transparent particles include titanium oxide, barium sulfate, magnesium carbonate, zinc oxide, clay, aluminum hydroxide, zinc sulfide, silica, and silicone. Examples of the metal particles or the metal foil include aluminum and silver. One kind of these high refractive index transparent particles, metal particles or metal foil may be used, or a plurality of kinds may be used in combination.

Furthermore, the absorption of light by the layer having the function of reflecting light must be within 1%. When it exceeds 1%, the integrated light quantity emitted from the first optical layer 1 is reduced, and the on-axis luminance is lowered regardless of the light control element for condensing light.

The shape of the fixing element 3 having a reflecting function is the same as that of the fixing element 3 having no reflecting function.

The integrated optical member produced as described above has an adhesive force that can withstand practical use as compared with a conventional integrated optical member. When used in a backlight, a display having a desired display performance can be provided by using the optical member of the present invention or another optical member in combination.

Examples will be described below.

(Method for producing first optical layer)
Example 1
A first mold roll cut into a shape of a convex cylindrical lens having a pitch of 140 μm was disposed in the vicinity of the extruder. A thermoplastic polycarbonate resin sheet was melted and molded by the extruder, and was molded by the first mold roll before the sheet was cooled and cured to obtain an optical layer having a lenticular lens. The thickness was 240 um.
In addition to the first mold roll, the first optical layer 1 having the fixing element 3 is arranged with a second mold roll in which hemispherical dots are irregularly arranged, and a lenticular lens in the same manner, An optical layer having hemispherical convex dots having a diameter of 70 μm, a height of 30 μm, and an average inter-dot distance of 250 μm was obtained on the opposite surface. The bonding area occupying the area of the optical member was 8%. The thickness was 240 um. In addition, as for the optical layer having the fixing element 3, the thermoplastic polycarbonate resin is transparent, and two types of styrene particles having a refractive index of 1.49 and a particle size of 2 μm are added to give a haze. Created using.

(Method for producing second optical layer)
(Example 2)
Using MS200 of Nippon Steel Chemical, the fixing element 3 was directly formed at the time of extruding the plate material. That is, the surface of the No. 1 cooling roll or the No. 2 cooling roll of the extruder was processed to form an uneven mold on the surface of the cooling roll. At the time of extruding the plate material, the concavo-convex shape was transferred to the plate material by a mold on the surface of the cooling roll. The shape of the fixing element 3 was a hemispherical convex dot having a diameter of 70 μm, a height of 30 μm, and an average inter-dot distance of 250 μm. The bonding area occupying the area of the optical member was 8%. The thickness was 2 mm.

(Method for producing adhesive)
(Example 3)
An acrylic resin adhesive was applied by a fountain reverse method to obtain a dry film having a thickness of 10 μm. Similarly, a 20% polystyrene filler with a particle size of 15 um was prepared to prepare a dry film having a thickness of 15 um.

(Bonding of optical layer with conventional structure)
Example 4
Each optical layer is cut to 500 mm × 800 mm, and an adhesive dry film is first laminated to the optical layer without the fixing element 3, and then the optical layer having the fixing element 3 is laminated to obtain an integrated optical member. It was.
(Example 5)
Each member was cut into 500 mm × 800 mm, and an adhesive dry film was first laminated on the optical layer having the fixing element 3, and then an optical layer without the fixing element 3 was laminated to obtain an integrated optical member. . By laminating a dry film of an adhesive on the optical layer having the fixing element 3 in advance, a part of the adhesive naturally adheres between the fixing elements, and an optical member having the structure of the present invention can be obtained. . The fixing element 3 of this time has an irregular arrangement with an average distance of 250 μm, and the adhesive naturally adheres between the fixing elements 3 at a distance exceeding this distance. On the other hand, it was rare that the adhesive was in close contact between the fixing elements 3 for the portion below this distance.

(Measurement of adhesion)
(Example 6)
Samples obtained by the above method are shown in Table 1 based on combinations of materials and joining methods. The central part of these samples was cut out to 10 cm × 30 cm, the first optical layer 1 was grasped, and a peel test was performed under the conditions of 180 °, 1000 mm / min peel, and width 25 mm. The results are shown in Table 1.
From the results, it was found that the difference in the joining method was very large compared to the difference in materials. In the case where neither the first optical layer 1 nor the second optical layer 5 has the fixing element 3, an adhesive having a peel strength of 1.7 N / 25 mm or more (unmeasurable) is 0.22 N through the fixing element 3. / 25mm was found to fall. This level of adhesion was very easy to peel and handling was difficult. However, when the front luminance incorporated in the backlight is compared, when both the first optical layer 1 and the second optical layer 5 do not have the fixed element 3, the front luminance is about 40 as compared with the case where either one has the fixed element 3. %, And the function as an optical member was not expressed. That is, it can be determined that the gap 2 held by the fixing element 1 and the fixing element 3 is essential.
Next, when the combination of the first optical layer 1 and the second optical layer 5 including the fixing element 3 is compared between the conventional configuration and the configuration of the present invention, the configuration of the present invention is a number compared to the conventional configuration. Double peel strength was exhibited. This is because the contact surface is not only the fixed element 3 but also between the fixed elements 3, so that the adhesion is dramatically improved.

(Reliability check)
(Example 7)
The optical member of the present invention having high peel strength was put into an environment at 80 ° C. for 500 hours, and the state of peeling was observed. As a result, the configuration of the present invention did not peel off after the test, compared to the conventional configuration that was difficult even at room temperature handling. This is considered due to the strength of peel strength.

(Verification of adhesion area and unevenness visibility)
(Example 8)
The fixing element 3 is formed on the first optical layer 1, the shape is 70 μm in diameter, 30 μm in height, and hemispherical convex dots. By increasing or decreasing the number, adhesion to the surface having the fixing element 3 as shown in Table 2 is achieved. An optical member having a different adhesion area with the agent was prepared. This optical member was incorporated into a backlight having a CCFL light source, and a liquid crystal panel was placed on it to check whether there was any abnormality in the appearance. As a result, when the adhesion area was less than 25%, uneven distribution of the adhesion portion was visually recognized as unevenness. For this reason, the adhesion area is desirably 25% or more. However, if a diffusion film is provided between the optical member and the liquid crystal panel, unevenness becomes difficult to recognize. Therefore, it is considered that there is no problem depending on the laminated structure of the optical member.

Explanatory drawing which shows the structural example of the display using the integrated optical member of this invention. It is the schematic which shows an example of white LED as a light source It is the schematic which shows an example of white LED as a light source. It is the schematic which shows the combination of white LED as a light source. It is the schematic which shows an example of a semiconductor laser as a light source. It is the schematic which shows an example of a 1st optical layer. It is the schematic which shows the structural example of the integrated optical member of this invention. It is the schematic which shows the comparative example of the integrated optical member of this invention. FIG. 3 is a schematic view showing a fixing element 3. It is the schematic which shows the adhesion location and light ray figure of the adhesive agent layer 4. FIG. Explanatory drawing which shows the structural example of the integrated optical member which concerns on a prior art. It is explanatory drawing which shows the structural example of the liquid crystal display device by a prior art. It is explanatory drawing which shows the structural example of the liquid crystal display device by a prior art. It is explanatory drawing which shows the structural example of the liquid crystal display device by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st optical layer 2 Cavity 3 Fixing element 4 Adhesive / adhesive layer 5 2nd optical layer 10 Optical member 13 Diffusion sheet 15 Light source 17 Reflector 19 Liquid crystal layer 21 Polarizing plate 46 White LED
47 LED substrate 48 Red LED element 49 Green LED element 50 Blue LED element 51 Phosphor 53 LED lens 54 Red LED
55 Green LED
56 Blue LED
57 Red semiconductor laser 58 Blue semiconductor laser 59 Blue semiconductor laser 60 Fiber 61 Semiconductor laser lens K Light from the light source L Light emitted from the optical member S Viewing direction of the display H Fixed element height

Claims (9)

Used for lighting path control for displays ,
A first optical layer and a second optical layer;
Having a fixing element in either one of the first optical layer or the second optical layer;
An optical member in which an entrance surface of the first optical layer and an exit surface of the second optical layer are partially integrated via an adhesive / adhesive layer,
An optical member having the fixing element in the first optical layer,
In a place where the distance between the adjacent fixing elements is 250 um or less,
The adhesive / adhesive layer is
The optical member, wherein the top of the adjacent fixing element is in contact with only the exit surface of the second optical layer.
Used for lighting path control for displays ,
A first optical layer and a second optical layer;
Having a fixing element in either one of the first optical layer or the second optical layer;
An optical member in which an entrance surface of the first optical layer and an exit surface of the second optical layer are partially integrated via an adhesive / adhesive layer,
An optical member having the fixing element in the second optical layer,
In a place where the distance between the adjacent fixing elements is 250 um or less,
The adhesive / adhesive layer is
A top of the adjacent fixing element;
An optical member that is in contact with only the incident surface of the first optical layer. The area of the fixing element, according to claim 1 or claim wherein said first or less than 50% 1% of the total area of the exit surface of the incident surface or the second optical layer of the optical layer Item 3. The optical member according to Item 2. 4. The optical member according to claim 1 , wherein a thickness of the adhesive / adhesive layer is within 1 time with respect to a height of the fixing element . 5. The optical member according to any one of claims 1 to 4 , wherein the adhesive / adhesive layer is not in contact with a side surface portion of the fixing element. 6. The optical member according to claim 1, wherein a shielding layer is provided on a surface of the fixing element . The adhesive / adhesive layer has a storage elastic modulus of 0.1 to 0.5 (Mpa / 25 ° C.) and a loss elastic modulus of 0.1 to 0.4 (Mpa / 25 ° C.). An optical member according to any one of claims 1 to 6 . On the back of the image display element that defines the display image,
A display backlight unit comprising at least a light source and the optical member according to claim 1 . 9. A display comprising: an image display element comprising a liquid crystal display element that defines a display image according to transmission / shading in pixel units; a light source; and the backlight unit according to claim 8 .