# US 2017/0287408 A1 · Black duty insertion mode liquid crystal display for virtual reality > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0287408 A1 - Document ID: US20170287408A1 - Status: Published application - Kind: A1 - Application number: 15/475,790 - Filed: 2017-03-31 - Published: 2017-10-05 - Earliest claimed: 2016-04-01 - Assignees: Oculus VR, LLC - Applicants: Oculus VR, LLC - Inventors: Jianru Shi; Fenglin Peng - Web page: https://patentgrep.com/patent/US20170287408A1 ## CPC - G09G 3/3406: {Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336)} - G02B 27/01: Head-up displays - G02B 27/017: {Head mounted} - G02C 7/101: {having an electro-optical light valve (electro-optical elements per se G02F)} - G02F 1/1336: {Illuminating devices} - G02F 1/133601: {for spatial active dimming} - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G02C: SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES (trial frames for testing the eyes A61B3/04; goggles or eyeshields not having the same features as spectacles A61F9/00) - 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 head mounted display (HMD) includes a display device that uses a black duty insertion mode. The display device includes a liquid crystal (LC) panel, a back light unit (BLU), and a data driver. In the black duty insertion mode, the BLU emits light during a portion of a frame period and does not emit light during a remaining portion of the frame period. The data driver writes data to the LC panel such that liquid crystal material in the LC panel transitions during the frame period including the portion of the frame period that the BLU emits light. The portion of the frame period the BLU emits light is less than half of the frame period and may be 20% or less of the frame period. ## Claims ### Claim 1 A display device comprising: a liquid crystal (LC) panel; a back light unit (BLU) configured to emit light; and a data driver configured to write data to the LC panel, wherein the BLU emits light during a portion of a frame period and does not emit light during a remaining portion of the frame period, and wherein the data driver writes data to the LC panel such that liquid crystal material in the LC panel transitions during the frame period including the portion of the frame period that the BLU emits light. ### Claim 2 (depends on 1) The display device of claim 1, wherein the data driver writes data to the LC panel during a beginning portion of the frame period. ### Claim 3 (depends on 1) The display device of claim 1, wherein the portion of the frame period the BLU emits light is less than half of the frame period. ### Claim 4 (depends on 3) The display device of claim 3, wherein the portion of the frame period the BLU emits light is 20% or less of the frame period. ### Claim 5 (depends on 1) The display device of claim 1, wherein the LC panel comprises a plurality of rows of pixels and the data driver writes display data to the LC panel from a first row to a last row of the pixels during the frame period and the portion of the frame period the BLU emits light is at an end portion of the frame period. ### Claim 6 (depends on 5) The display device of claim 5, wherein the data driver writes data to a row of the pixels between the first row and the last row of the pixels of the LC panel during the remaining portion of the frame period the BLU does not emit light. ### Claim 7 (depends on 5) The display device of claim 5, wherein the data driver writes data to the last row of the pixels of the LC panel during the remaining portion of the frame period the BLU does not emit light. ### Claim 8 (depends on 5) The display device of claim 5, wherein the liquid crystal material in a row of the pixels between the first row and the last row of the pixels of the LC panel transitions during the portion of the frame period the BLU emits light. ### Claim 9 (depends on 5) The display device of claim 5, wherein the liquid crystal material in the last row of the pixels of the LC panel transitions during the portion of the frame period the BLU emits light. ### Claim 10 (depends on 1) The display device of claim 1, further comprising: a controller coupled to the data driver and the BLU, the controller configured to: apply a first control signal to the data driver to write data to a plurality of rows of the LC panel during the frame period; and apply a second control signal to the BLU to emit light during the portion of the frame period and to not emit light during the remaining portion of the frame period. ### Claim 11 A display device comprising: a liquid crystal (LC) panel; a back light unit (BLU) configured to emit light; and a data driver configured to write data to the LC panel, wherein the BLU emits light during a portion of a frame period and does not emit light during a remaining portion of the frame period, and wherein the data driver writes data to the LC panel during a first portion of the frame period such that liquid crystal material in the LC panel transitions during the portion of the frame period the BLU emits light. ### Claim 12 (depends on 11) The display device of claim 11, wherein the first portion of the frame period is contained in the remaining portion of the frame period. ### Claim 13 (depends on 11) The display device of claim 11, wherein the portion of the frame period the BLU emits light is less than half of the frame period. ### Claim 14 (depends on 13) The display device of claim 13, wherein the portion of the frame period the BLU emits light is 20% or less of the frame period. ### Claim 15 (depends on 11) The display device of claim 11, wherein the LC panel comprises a plurality of rows of pixels and the data driver writes display data to the LC panel from a first row to a last row of the pixels during the first portion of the frame period and the portion of the frame period the BLU emits light is at an end portion of the frame period. ### Claim 16 (depends on 15) The display device of claim 15, wherein the liquid crystal material in a row of the pixels between the first row and including the last row of the pixels of the LC panel transitions during the portion of the frame period the BLU emits light. ### Claim 17 (depends on 11) The display device of claim 11, further comprising: a controller coupled to the data driver and the BLU, the controller configured to: apply a first control signal to the data driver to write data to a plurality of rows of the LC panel during the first portion of the frame period; and apply a second control signal to the BLU to emit light during the portion of the frame period and to not emit light during the remaining portion of the frame period. ### Claim 18 A display device comprising: a liquid crystal (LC) panel; a data driver configured to write data to the LC panel; a back light unit (BLU) configured to emit light; and a controller coupled to the data driver and the BLU, the controller controlling the data driver to write data to a plurality of rows of the LC panel during a frame period from a frame period start time to a write period end time and instructing the BLU to emit light from an illumination start time to the frame period end time, the illumination start time occurring after the write period end time and at a predetermined timing between the frame period start time and the frame period end time, wherein liquid crystal material in the LC panel transitions after the illumination start time and before the frame period end time. ### Claim 19 (depends on 18) The display device of claim 18, wherein the illumination start time occurs during a last 20% of the frame period. ### Claim 20 (depends on 18) The display device of claim 18, wherein the frame period is 11 milliseconds, and the illumination start is 2 milliseconds before the frame period end time.