# US 2009/0262284 A1 · Transflective liquid crystal display > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0262284 A1 - Document ID: US20090262284A1 - Status: Published application - Kind: A1 - Application number: 11/721,878 - Filed: 2005-11-22 - Published: 2009-10-22 - Earliest claimed: 2004-12-18 - Assignees: Merck Patent GmbH - Inventors: Rick Hamilton - Web page: https://patentgrep.com/patent/US20090262284A1 ## CPC - G02F 1/133555: {Transflectors} - G02F 1/13363: Birefringent elements, e.g. for optical compensation - G02F 1/133528: {Polarisers} - G02F 1/133565: {inside the LC elements, i.e. between the cell substrates} - G02F 1/133631: {with a spatial distribution of the retardation value} - G02F 1/133633: {using mesogenic materials} - G02F 1/133638: {Waveplates, i.e. plates with a retardation value of lambda/n} - G02F 1/1337: Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers - G02F 2413/01: Number of plates being 1 - G02F 2413/08: with a particular optical axis orientation - 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 The invention relates to a transflective liquid crystal display (LCD) comprising a patterned quarter wave foil (QWF) and having improved chromaticity. ## Claims ### Claim 1 Transflective liquid crystal display (LCD) comprising one or more pixels that are divided into a reflective and a transmissive subpixel and comprise an LC layer sandwiched between a front and a back electrode, being switchable between different orientations upon application of an electric field and having a twist angle φ when no field is applied, a front and a back polariser sandwiching the LC layer and having front and back polarisation directions, at least one quarter wave retardation film (QWF) between the front polariser and the LC layer, which has an optical axis parallel to its film plane, comprises a pattern of regions with quarter wave (λ/4) retardation and regions with substantially no retardation, and is arranged such that the λ/4-regions do essentially cover only the reflective subpixels, characterized in that the optical axis of the QWF is oriented at an angle of approximately 45° to the front and back polariser direction, the director of the LC layer at the surface facing the front electrode is oriented at an angle θ1 of from 5 to 45° relative to the polarisation direction of the front polariser, and the director of the LC layer at the surface facing the back electrode is oriented at an angle θ2 of from 5 to 45° relative to the polarisation direction of the back polariser. ### Claim 2 (depends on 1) LCD according to claim 1, characterized in that it has a twist angle φ from 40° to 110°. ### Claim 3 (depends on 1) LCD according to claim 1, characterized in that it has a twist angle φ of 90°. ### Claim 4 (depends on 1) LCD according to claim 1, characterized in that θ1 and θ2 are from 10° to 20°. ### Claim 5 (depends on 1) LCD according to claim 1, characterized in that θ1 and θ2 are 15°. ### Claim 6 (depends on 1) LCD according to claim 1, characterized in that the thickness of the QWF is from 0.5 to 3.5 microns. ### Claim 7 (depends on 1) LCD according to claim 1, characterized in that the on-axis retardation of the QWF is from 100 to 175 nm. ### Claim 8 (depends on 1) LCD according to claim 1, characterized in that it comprises a liquid crystal (LC) cell comprising the following elements a first and a second substrate plane parallel to each other, at least one of which is transparent to incident light, an array of nonlinear electric elements provided on one of said substrates which can be used to individually switch individual pixels of said LC cell, like transistors, a colour filter array provided on one of said substrates, and having a pattern of different pixels transmitting one of the primary colours red, green and blue (R, G, B), said colour filter optionally being covered by a planarisation layer, a first electrode layer provided on the inside of said first substrate, optionally a second electrode layer provided on the inside of said second substrate, optionally first and second alignment layers provided on said first and second electrodes, an LC layer sandwiched between the electrodes or alignment layers, which is switchable between different orientations by application of an electric field and has a twist angle φ when no field is applied, a first linear polariser on the first side of the LC cell, a second linear polariser on the second side of the LC cell, and at least one QWF as defined in the preceding claims, wherein the orientation directions of the polarisers, QWF and LC layer are as defined in the preceding claims. ### Claim 9 (depends on 1) LCD according to claim 1 characterized in that the QWF is positioned between the colour filter and the proximate electrode. ### Claim 10 (depends on 1) LCD according to claim 1, characterized in that it comprises a colour filter having a pattern of R-, G-, B-pixels, and the QWF exhibits a pattern of R-, G- and B-pixels having different retardation that is adjusted such that the efficiency of converting linearly polarised light into circularly polarised light is optimised for the colour R, G and B, respectively, said QWF being positioned such that each of its R-, G- and B-pixels covers the corresponding R-, G- and B-pixels of the colour filter.