Source: http://www.google.com/patents/US20060002149?ie=ISO-8859-1&dq=6,563,928
Timestamp: 2015-03-05 07:35:36
Document Index: 23741142

Matched Legal Cases: ['art 350', 'art 350', 'art 410', 'art 410', 'arts 512', 'arts 512', 'art 410', 'art 410', 'art 410', 'art 410', 'art 410']

Patent US20060002149 - Prism sheet of liquid crystal display device and backlight unit using the same - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA prism sheet of an LCD includes a body part made of a transparent resin material and a plurality of polypyramid-shaped optical unit structures formed in a intaglio type on the body part. The plurality of optical unit structures have intaglio-type polypyramid shapes in an inside of their polygonal structure....http://www.google.com/patents/US20060002149?utm_source=gb-gplus-sharePatent US20060002149 - Prism sheet of liquid crystal display device and backlight unit using the sameAdvanced Patent SearchPublication numberUS20060002149 A1Publication typeApplicationApplication numberUS 11/024,767Publication dateJan 5, 2006Filing dateDec 30, 2004Priority dateJul 2, 2004Also published asCN1716027A, CN1716027B, US7252428Publication number024767, 11024767, US 2006/0002149 A1, US 2006/002149 A1, US 20060002149 A1, US 20060002149A1, US 2006002149 A1, US 2006002149A1, US-A1-20060002149, US-A1-2006002149, US2006/0002149A1, US2006/002149A1, US20060002149 A1, US20060002149A1, US2006002149 A1, US2006002149A1InventorsSang Lee, Chang Kim, Young Kim, Yun Choi, Ho Chin, Bong Hong, Kab Hwang, Ung Lee, Chul KimOriginal AssigneeLee Sang G, Kim Chang J, Kim Young G, Choi Yun H, Chin Ho S, Hong Bong T, Hwang Kab J, Lee Ung S, Kim Chul YExport CitationBiBTeX, EndNote, RefManReferenced by (8), Classifications (6), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetPrism sheet of liquid crystal display device and backlight unit using the same
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings. FIGS. 3A and 3B are cross-sectional views illustrating a construction of a backlight unit of an LCD according to the present invention. Referring to FIGS. 3A and 3B, a backlight unit 300 according to the present invention includes a lamp unit 310 for generating light, and a light guide unit for guiding the light from the lamp unit 310 toward a liquid crystal display panel. Here, the light guide unit has a plurality of optical sheets 340. Among those optical sheets 340, a prism sheet 344 is configured in such a way that a plurality of polypyramid-shaped optical unit structures 360 made of PMMA (Polymethylmethacrylate) are arranged on a body part made of a transparent resin material, such as PET (polyethyleneterephthalate) or PC (Polycarbonate). At this point, the plurality of optical unit structures 360 arranged and formed on the prism sheet 344 is configured such that a polypyramid shape is formed in an intaglio or recessed type in an inside of their polygonal structure and a center of the intaglio portion, which corresponds to a vertex of the polypyramid, forms a point. Further, when a light-concentrating degree of the prism sheet 344 and a viewing angle characteristics need to be adjusted or compromised, it is possible to obtain such an adjustment compromise by changing a shortest distance between central points of the optical unit structures formed in plural on the body part 350 and a depth of the optical unit structure. For example, in case one side of the prism sheet 344 on which the optical unit structures 360 are formed becomes a light outputting surface, the light-concentrating degree may be designed such that the depth of the optical unit structure 360 is smaller than a shortest distance between central points of the intaglio-type optical unit structures 360. That is, the depth of the optical unit structure 360 may be determined in a range of about 0.3-0.6 times the shortest distance between the central points. Further, even in case one side of the prism sheet 344 on which the optical unit structures 360 are formed becomes a light receiving surface, the light-concentrating degree may be designed such that the depth of the optical unit structure 360 is smaller than a shortest distance between central points of the intaglio-type optical unit structures 360. At this point, the depth of the optical unit structure may be determined in a range of about 0.5-0.8 times the shortest distance between the central points. The transparent resin material constituting the body part 350 may have a transmittance of more than about 70%. The transparent resin material may be formed on one side of the body part, i.e., a surface opposite to the surface where the optical unit structures 360 are formed, by embossing small-sized protuberances acting as structures for diffusing light or by providing grains made of PMMA, which is a material for diffusing light into an inside of the body part. Further, the lamp unit 310 includes: a lamp 312 for generating light; and a lamp reflector 314 enclosing the lamp 312. Light emitted from the lamp 312 is incident into a light guide plate 312 and the lamp reflective plate 330 improves an amount of light incident to the light guide plate 320 by reflecting the light emitted from the lamp 312 toward the light guide plate 320, which are the same as the construction of the general lamp unit. Here, the light guide unit includes: the reflective plate 330; the light guide plate 320; and the optical sheets 340. The light guide plate 320 is provided to one side of the lamp unit 310 to guide the light emitted from the lamp unit 310. At this point, the light guide plate 320 changes a path of the light emitted from the lamp unit 310 to guide the light toward the liquid crystal display panel. The reflective plate 330 is disposed beneath the light guide plate 320 and reflects light leaked from the light guide plate 320 back to the light guide plate 320. The plurality of optical sheets 340 are disposed on the light guide plate 320 to enhance efficiency of the light that has passed through the light guide plate 320. Specifically, the optical sheets 340 include a diffusion sheet 342; a prism sheet 344; and a protective sheet 346. Those sheets are sequentially stacked on the light guide plate 320. The diffusion sheet 342 scatters the light that is incident from the light guide plate 320, thereby making uniform the brightness distribution of the light. Further, the above-described prism sheet 344 of the present invention may be arranged such that the plurality of intaglio-type optical unit structures is opposite to the diffusion sheet 342 as shown in FIG. 3A, or may be arranged such that the other surface on which the protrusion parts are not formed is opposite to the diffusion sheet 342, that is, the other surface becomes a light outputting surface as shown in FIG. 3B. However, in case small-sized protuberances acting as structures for diffusing light are embossed on a surface of the body part of the prism sheet, i.e., a surface opposite to the surface where the optical unit structures are formed, the diffusion sheet may be omitted. Further, the protective sheet 346 provided on the prism sheet 344 diffuses the light in order to make uniform a distribution of the light incident from the prism sheet 346 as well as protects a surface of the prism sheet 344. The protective sheet 346 may be removed depending on cases. FIGS. 4A and 4B are a perspective view and a cross-sectional view illustrating a prism sheet of an LCD according to the present invention. Here, the prism sheet explained with reference to FIG. 4 is the same as the prism sheet provided to the backlight unit explained earlier with reference to FIG. 3 As illustrated in FIG. 4, the prism sheet according to the present invention is configured in such a way that a plurality of intaglio-type polypyramid-shaped optical unit structures 420 made of PMMA(polymethylmethacrylate) is arranged on a body part made of a transparent resin material, such as PET(polyethyleneterephthalate) or PC(Polycarbonate). Here, the transparent resin material constituting the body part may have a transmittance of more than 70%. The transparent resin material can be formed on one side of the body part, i.e., a surface opposite to the surface where the optical unit structures are formed, by embossing small-sized protuberances acting as structures for diffusing light or by providing grains made of PMMA, which is a material for diffusing light into an inside of the body part. A thickness of the body part 410 may be at least more than 25 μm. At this point, the plurality of optical unit structures 420 arranged and formed on the prism sheet 400 is configured such that a polypyramid shape is formed in an intaglio type in an inside of their polygonal structures and a center of the intaglio portion, which corresponds to a vertex of the polypyramid, forms a point. That is, the intaglio-type polypyramid shape is of an intaglio cubic structure in which vertexes of more than three isosceles triangles meet at one point, i.e., a center of the intaglio portion, and the isosceles triangle's plane acts as a refraction plane of light. For example, the optical unit structure 420 may be realized in form of an intaglio type quadrangular pyramid formed in an inside of a quadrangular structure as shown in FIG. 4. Further, when a light-concentrating degree of the prism sheet and a viewing angle characteristics need to be compromised, it is possible to obtain such a compromise by adjusting a shortest distance p between central points of the optical unit structures 420 formed in plural on the body part 410 and a depth h of the optical unit structure. For example, in case one side of the prism sheet on which the optical unit structures 420 are formed becomes a light outputting surface, the light-concentrating degree may be designed such that the depth of the optical unit structure 420 is smaller than a shortest distance between central points of the intaglio-type optical unit structures 420. That is, the depth h of the optical unit structure 420 may be determined in a range of about 0.3-0.6 times the shortest distance p between the central points. Further, even in case one side of the prism sheet on which the optical unit structures 420 are formed becomes a light receiving surface, the light-concentrating degree may be designed such that the depth h of the optical unit structure 420 is smaller than a shortest distance p between central points of the intaglio-type optical unit structures 420. At this point, the depth h of the optical unit structure may be determined in a range of about 0.5-0.8 times the shortest distance p between the central points. In addition, the depth h of the optical unit structure may be greater than at least about one fourth of the shortest distance p between the central points and may be greater than at least about 10 μm. Further, since the optical unit structures formed in an intaglio type on the prism sheet of the present invention has a plurality of isosceles triangular planes, a viewing angle characteristics can be considerably improved using each of the isosceles triangular planes as a light receiving plane. FIGS. 5A through 5C are perspective views illustrating part of a backlight unit according to an embodiment of the present invention. Referring to FIGS. 5A through 5C, an edge-type backlight assembly adopting an �L�-shaped lamp 500 is illustrated. A plurality of protrusion parts 512 are formed on a surface of a light guide plate 510, so that about 80% of light incident to the light guide plate 510 is emitted at a specific angle (about 60-80�). Here, the protrusion parts 512 formed on the surface of the light guide plate 510 may be formed in a stripe type of a prism shape as illustrated in FIG. 5A, or may be formed in a relief or an intaglio-type triangular pyramid as illustrated in FIGS. 5B or 5C. The lamp 500 is formed in an �L� shape so as to simultaneously provide light to two non-facing sides of the light guide plate 510. More than one lamp 500 may be provided. In that case, the prism sheet 400 of the present invention described with reference to FIG. 4 is inversely arranged, namely, optical unit structures 420 formed in an intaglio type on the prism sheet are arranged to face the light guide plate 510, whereby the light incident at a specific angle is refracted to various directions by a plurality of isosceles triangular planes constituting the optical unit structures 420 formed on the prism sheet 400 and uniform optical characteristics can be obtained over a wide range. That is, a viewing angle characteristics can be improved for all directions including up, down, left, and right. Further, the plurality of intaglio-type polypyramid-shaped optical unit structures 420 formed on the body part 410 is formed such that liquid PMMA material is made into a intaglio through a relief mold and formed on the body part 410 and then hardened by an ultraviolet hardening method to be finally combined with the body part 410. That is, for manufacturing of the prism sheet according to the present invention, a relief mold having almost the same size as the intaglio-type polypyramid-shaped optical unit structures formed on the prism sheet is used. For the mold, a metallic material may be used or a material having a property that can be bent, such as a resin, may be used depending on case. The mold may be prepared by forming a relief on a metal surface basically having a curved surface or by forming a relief on resin surface that can be bent, considering its exfoliation (extraction) property and handling property. By manufacturing the prism sheet on which the intaglio-type polypyramid-shaped optical unit structures are formed using the relief mold as described above, it is possible to efficiently produce, with high productivity, the optical unit structures contributing to reflection and refraction of light. That is, it is possible to raise a manufacturing speed and improve optical characteristics maximally by forming the optical unit structures of the prism sheet according to the present invention, using an intaglio method. FIG. 6 is a view explaining a manufacturing of the prism sheet according to the present invention. Referring to FIG. 6, the prism sheet according to the present invention is manufactured such that a transparent resin material 420 of liquid state is injected between a relief mold 500 and a body part 410 made of a transparent resin material, and an appropriate pressure is applied thereon; the liquid resin material is hardened by an ultraviolet apparatus 510 so as to be combined with the body part 410, so that the prism sheet is finally obtained by being exfoliating (extracting) from the relief mold 500. A method for manufacturing a first mold having an excellent uniformity in its shape through a machine process using a ultra-hardness tool such as a diamond is already known in the art and the prism sheet of the present invention can be manufactured using the first relief mold obtained through the above-mentioned machine process. At this point, for a material used in manufacturing the first mold, a resin material may be used, and more preferably, a metal material my be used considering durability. Further, to lengthen even more a life of the first mold obtained through the above-mentioned machine process, a second mold having an intaglio may be duplicated from the first mold and then a third mold having a relief may be again duplicated from the second mold and used for manufacturing the prism sheet. If necessary, after the second molds are duplicated through mass production, the third molds are duplicated from the second molds and may be used as relief molds for producing the prism sheet of the present invention. As described above, according to the present invention, polypyramid-shaped optical unit structures are provided in form of an intaglio type on one side of the prism sheet, whereby light from all directions including up, down, left, and right is concentrated and a brightness increase/decrease can be achieved. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. Referenced byCiting PatentFiling datePublication dateApplicantTitleUS7220026Dec 30, 2004May 22, 20073M Innovative Properties CompanyOptical film having a structured surface with offset prismatic structuresUS7320538Dec 30, 2004Jan 22, 20083M Innovative Properties CompanyOptical film having a structured surface with concave pyramid-shaped structuresUS7416309Dec 30, 2004Aug 26, 20083M Innovative Properties CompanyOptical film having a surface with rounded structuresUS7466373 *Jan 3, 2006Dec 16, 2008Polytronix, Inc.Flat panel displays with primary viewing envelopes away from displyay panel normalUS7545569Nov 8, 2006Jun 9, 2009Avery Dennison CorporationOptical apparatus with flipped compound prism structuresUS7936411May 29, 2008May 3, 2011Samsung Electronics Co., Ltd.Light guide plate, backlight assembly including the same, and liquid crystal display device including the sameEP1998197A1 *Mar 29, 2008Dec 3, 2008Samsung Electronics Co., Ltd.Light guide plate, backlight assembly including the same, and liquid crystal display device including the sameWO2007081632A1 *Dec 12, 2006Jul 19, 2007Optical Res AssociatesOptical apparatus with flipped compound prism structures* Cited by examinerClassifications U.S. Classification362/627International ClassificationF21V7/04Cooperative ClassificationG02B6/0065, G02B6/0053European ClassificationG02B6/00L6O8P, G02B6/00L6PLegal EventsDateCodeEventDescriptionDec 27, 2010FPAYFee paymentYear of fee payment: 4Aug 5, 2008CCCertificate of correctionDec 30, 2004ASAssignmentOwner name: LG ELECTRONICS, INC., KOREA, REPUBLIC OFFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LEE, SANG GON;CHOI, YUN HO;HWANG, KAB JIN;AND OTHERS;REEL/FRAME:016141/0182Effective date: 20041125RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services