# US 9,519,154 B2 · Diffraction grating for use with a multi-layered display system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,519,154 B2 - Document ID: US9519154B2 - Status: Granted - Kind: B2 - Application number: 14/454,607 - Filed: 2014-08-07 - Published: 2015-11-12 - Granted: 2016-12-13 - Earliest claimed: 2014-05-09 - Assignees: Pure Depth Limited - Applicants: Pure Depth Limited - Inventors: Gareth Bell - Web page: https://patentgrep.com/patent/US9519154B2 ## CPC - G02B 27/4216: {correcting geometrical aberrations} - G02B 5/30: Polarising elements (light-modulating devices with active elements G02F1/00) - G02B 27/42: Diffraction optics {, i.e. systems including a diffractive element being designed for providing a diffractive effect}(G02B27/60 takes precedence) - G02B 27/46: Systems using spatial filters - G02B 27/60: Systems using moiré fringes - G02F 1/133504: {Diffusing, scattering, diffracting elements (associated to illuminating devices G02F1/133606)} - G02F 1/1347: Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells - 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 display device is described and includes a first display screen including a mask pattern of a pixel. The display device includes a second display screen including the mask pattern, wherein the second display screen is located further from a front of the display device than the first display screen, wherein the front of the display device is closest to a viewer. The display device includes a diffraction element configured to copy the mask pattern of the second display screen into one or more viewable copies in order to minimize moiré interference with the mask pattern of the first display screen. ## Claims ### Claim 1 A display device comprising: a first display screen comprising a mask pattern of a pixel; a second display screen comprising said mask pattern, wherein said second display screen is located further from a front of said display device than said first display screen, wherein said front of said display device is closest to a viewer; a diffraction element configured to convolve said mask pattern of said second display screen into one or more viewable copies in order to minimize moiré interference with said mask pattern of said first display screen, wherein said diffraction element is located between said first display screen and said second display screen; wherein said mask pattern comprises a first portion repeatable in a first direction, and wherein said diffraction element is configured to copy said first portion of said mask pattern in said first direction; and wherein a number of said viewable copies is based on dividing a width of said pixel by a width of said first portion. ### Claim 2 (depends on 1) The display device of claim 1, wherein said first direction comprises a horizontal direction. ### Claim 3 (depends on 1) The display device of claim 1, wherein said first direction comprises a vertical direction. ### Claim 4 (depends on 1) The display device of claim 1, wherein said number of viewable copies completely covers said pixel in said first direction, such that a spacing of said one or more viewable copies comprises said width of said first portion. ### Claim 5 (depends on 1) The display device of claim 1, wherein said one or more viewable copies are generated within a footprint of said pixel. ### Claim 6 (depends on 1) The display device of claim 1, wherein said diffraction element comprises an odd number of slits. ### Claim 7 (depends on 1) The display device of claim 1, wherein said number of copies comprises four or more orders. ### Claim 8 A method for treating moiré interference in a display device, the method comprising: providing a first display screen comprising a mask pattern of sub-pixels of a pixel, wherein said mask pattern prevents transmission of light intensity; providing a second display screen comprising said mask pattern, wherein said second display screen is located further from a front of said display device than said first display screen, wherein said front of said display device is closest to a viewer; convolving said mask pattern of said second display screen into one or more viewable copies in order to minimize moiré interference with said mask pattern of said first display screen; said convolving comprising convolving a first portion of said mask pattern in a first direction, wherein said first portion is repeatable in said first direction; and determining a number of said viewable copies based on dividing a width of said pixel by a width of said first portion, wherein said number of viewable copies completely covers said pixel in said first direction, such that a spacing of said one or more viewable copies comprises said width of said first portion. ### Claim 9 (depends on 8) The method of claim 8, further comprising: providing a diffraction element configured to convolve said first portion of said mask pattern in said first direction. ### Claim 10 (depends on 9) The method of claim 9, further comprising: configuring said diffraction element to comprise an odd number of slits. ### Claim 11 (depends on 8) The method of claim 8, wherein said first direction comprises a horizontal direction. ### Claim 12 (depends on 8) The method of claim 8, wherein said first direction comprises a vertical direction. ### Claim 13 (depends on 8) The method of claim 8, wherein said one or more viewable copies are generated within a footprint of said pixel. ### Claim 14 (depends on 8) The method of claim 8, wherein said number of copies comprises four or more orders. ### Claim 15 (depends on 8) The method of claim 8, wherein said diffraction element is nearer to said front of said display device than said first display screen and said second display screen. ### Claim 16 (depends on 1) The display device of claim 1, wherein said pixel is a subpixel. ### Claim 17 A display device comprising: a first display screen comprising a pixel; a second display screen comprising a mask pattern located further from a front of said display device than said first display screen, wherein said front of said display device is configured to be closest to a viewer; a diffraction element configured to convolve said mask pattern of said second display screen into one or more viewable copies in order to reduce moiré interference with said first display screen; wherein said mask pattern of said second display screen comprises a first portion repeatable in a first direction, and wherein said diffraction element is configured to copy said first portion of said mask pattern in said first direction; and wherein a number of said viewable copies is based on dividing a width of said pixel by a width of said first portion. ### Claim 18 (depends on 17) The display device of claim 17, wherein said pixel is a subpixel. ### Claim 19 (depends on 17) The display device of claim 17, wherein said first display screen comprises a plurality of pixels. ### Claim 20 A display device comprising: a first display screen comprising a pixel; a second display screen comprising a mask pattern located further from a front of said display device than said first display screen, wherein said front of said display device is configured to be closest to a viewer; a diffraction element configured to convolve at least part of said mask pattern of said second display screen into a plurality of adjacent copies so as to reduce moiré interference with said first display screen; and wherein said part of said mask pattern of said second display screen is repeatable in a first direction, and wherein said diffraction element is configured to copy at least said part of said mask pattern in said first direction and convolve at least said part of said mask pattern into the plurality of adjacent copies so as to reduce moiré interference with said first display screen by spreading the copies across a given pixel of the first display screen in order to cause said part of said mask pattern to substantially disappear. ### Claim 21 (depends on 20) The display device of claim 20, wherein said pixel is a subpixel. ### Claim 22 (depends on 20) The display device of claim 20, wherein said first display screen comprises a plurality of pixels.