# US 7,407,317 B2 · Prism sheet and backlight unit using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,407,317 B2 - Document ID: US7407317B2 - Status: Granted - Kind: B2 - Application number: 11/314,342 - Filed: 2005-12-22 - Published: 2007-01-04 - Granted: 2008-08-05 - Earliest claimed: 2005-06-29 - Assignees: LG Display Co., Ltd. - Inventors: Man Hoan Lee; Jae Kyung Kang; Ji Su Yoon; Sung Keun Lee; Won Taek Moon - Web page: https://patentgrep.com/patent/US7407317B2 ## CPC - G02B 6/0053: {Prismatic sheet or layer; Brightness enhancement element, sheet or layer} - G02F 1/133606: {including a specially adapted diffusing, scattering or light controlling members} - G02F 1/133607: {the light controlling member including light directing or refracting elements, e.g. prisms or lenses} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract A prism sheet capable of achieving an enhancement in light efficiency and viewing angle characteristics and a backlight unit using the prism sheet are disclosed. The prism sheet includes: a condensing film which transmits light incident to the condensing film; a plurality of prism crests on the condensing film having apexes; and a plurality of reflection patterns formed on the condensing film such that each of the reflection patterns faces a boundary of adjacent prism crests associated with the reflection pattern to reflect light incident onto the reflection patterns. ## Claims ### Claim 1 A prism sheet comprising: a condensing film which transmits light incident to the condensing film; a plurality of prism crests on the condensing film, each prism crest having a pair of sloping sides that intersect to form an apex of the prism crest, and wherein facing sloping sides of adjacent ones of the prism crests define valleys between the adjacent ones of the prism crests on the condensing film; and a plurality of reflection patterns formed on the condensing film such that each of the reflection patterns faces and overlaps a valley between adjacent prism crests to reflect light incident onto the reflection patterns, wherein there is a one to one correspondence between the reflection patterns and the valleys between adjacent prism crests. ### Claim 2 (depends on 1) The prism sheet according to claim 1, wherein each of the prism crests has one of a strip shape and a pyramid shape. ### Claim 3 (depends on 1) The prism sheet according to claim 1, wherein the reflection patterns are formed on one of an upper surface and a lower surface of the condensing film. ### Claim 4 (depends on 1) The prism sheet according to claim 1, wherein the reflection patterns are arranged in the form of one of stripes and a matrix array. ### Claim 5 (depends on 1) The prism sheet according to claim 1, wherein the reflection patterns are made of one of titanium oxide (TiO2) and magnesium oxide (MgO). ### Claim 6 A backlight unit comprising: a lamp that emits light; a light guide plate that receives the light emitted from the light, and changes a path direction of the light to a direction substantially perpendicular to an upper surface of the light guide plate; and a prism sheet that condenses the light emerging from the light guide plate, wherein the prism sheet includes: a condensing film that transmits the light emerging from the light guide plate; a plurality of prism crests on the condensing film, each prism crest havina a pair of sloping sides that intersect to form an apex of the prism crest, and wherein facing sloping sides of adjacent ones of the prism crests define valleys between the adjacent ones of the prism crests on the condensing film; and a plurality of reflection patterns formed on the condensing film such that each of the reflection patterns faces and overlaps a valley between adjacent prism crests associated with the reflection pattern to reflect light incident onto the reflection patterns, wherein there is a one to one correspondence between the reflection patterns and the valleys between adjacent prism crests. ### Claim 7 (depends on 6) The backlight unit according to claim 6, wherein the lamp includes one of a lamp arranged at one side of the light guide plate and a pair of lamps respectively arranged at opposite sides of the light guide plate. ### Claim 8 (depends on 6) The backlight unit according to claim 6, further including: at least one lamp housing arranged at one of one side and opposite sides of the light guide plate to enclose an incidence face of the light guide plate and the lamp; a diffusion sheet arranged between the light guide plate and the prism sheet to diffuse the light emerging from the light guide plate; and a reflection plate arranged beneath a lower surface of the light guide plate. ### Claim 9 (depends on 6) The backlight unit according to claim 6, wherein each of the prism crests has one of a strip shape and a pyramid shape. ### Claim 10 (depends on 6) The backlight unit according to claim 6, wherein the reflection patterns are formed on one of an upper and a lower surface of the condensing film. ### Claim 11 (depends on 10) The backlight unit according to claim 10, wherein the reflection patterns are arranged in the form of one of stripes and a matrix array. ### Claim 12 (depends on 6) The backlight unit according to claim 6, wherein the reflection patterns are made of one of titanium oxide (TiO2) and magnesium oxide (MgO). ### Claim 13 A backlight unit comprising: a plurality of lamps that emit light; a bottom cover that receives and supports the lamps; a diffusion plate that covers an upper surface of the bottom cover and diffuses light emitted from the lamps; and a prism sheet that condenses light emerging from the diffusion plate, wherein the prism sheet includes: a condensing film that transmits the light emerging from the light guide plate; a plurality of prism crests on the condensing film, each prism crest having a pair of sloping sides that intersect to form an apex of the prism crest, and wherein facing sloping sides of adjacent ones of the prism crests define valleys between the adjacent ones of the prism crests on the condensing film; and a plurality of reflection patterns formed on the condensing film such that each of the reflection patterns faces and overlaps a valley between adjacent prism crests associated with the reflection pattern to reflect light incident onto the reflection patterns, wherein there is a one to one correspondence between the reflection patterns and the valleys between adjacent prism crests. ### Claim 14 (depends on 13) The backlight unit according to claim 13, wherein each of the prism crests has one of a strip shape and a pyramid shape. ### Claim 15 (depends on 13) The backlight unit according to claim 13, wherein the reflection patterns are formed on one of an upper or a lower surface of the condensing film. ### Claim 16 (depends on 15) The backlight unit according to claim 15, wherein the reflection patterns are arranged in the form of one of stripes and a matrix array. ### Claim 17 (depends on 13) The backlight unit according to claim 13, wherein the reflection patterns are made of one of titanium oxide (TiO2) and magnesium oxide (MgO). ### Claim 18 A prism sheet comprising: a condensing film that transmits light incident to the condensing film; a plurality of prism crests on the condensing film, each prism crest having a pair of sloping sides that intersect to form an apex of the prism crest, and wherein facing sloping sides of adjacent ones of the prism crests define valleys between the adjacent ones of the prism crests on the condensing film; and a plurality of reflection patterns formed on the condensing film such that each of the reflection patterns is aligned with and overlaps each valley defined between adjacent prism crests associated with the reflection pattern to reflect light incident onto the reflection patterns, wherein there is a one to one correspondence between the reflection patterns and the valleys between adjacent prism crests.