# US 2019/0169060 A1 · Selectively heat-treated glass-ceramic for an electronic device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0169060 A1 - Document ID: US20190169060A1 - Status: Published application - Kind: A1 - Application number: 15/986,778 - Filed: 2018-05-22 - Published: 2019-06-06 - Earliest claimed: 2017-12-01 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Christopher D. Jones; Matthew S. Rogers; Que Anh S. Nguyen - Web page: https://patentgrep.com/patent/US20190169060A1 ## CPC - C03B 32/02: Thermal crystallisation, e.g. for crystallising glass bodies into glass-ceramic articles {(C03B27/012 takes precedence)} - G06F 1/1637: {Details related to the display arrangement, including those related to the mounting of the display in the housing} - H04M 1/0266: {for a display module assembly} - G06F 1/1626: {with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]} - G06F 2200/1634: Integrated protective display lid, e.g. for touch-sensitive display in handheld computer - C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08) ## Abstract The embodiments disclosed herein are directed to forming selectively heat-treated glass-ceramic parts for use in an electronic device. In various embodiments, glass-ceramic parts, such as a cover sheet, may have multiple different regions having different objectives for material properties such as optical properties, strength, fracture toughness, hardness, and the like. Different regions may be selectively heat treated to achieve desired results. ## Claims ### Claim 1 A method for forming a glass-ceramic part comprising: heating a first region of a glass part to a first temperature that is at or above a crystallization temperature of the glass part; and maintaining a second region of the glass part at or below a second temperature that is below the first temperature, thereby converting the glass part to the glass-ceramic part, such that: the first region has a first median crystal size; and the second region has a second median crystal size that is less than the first median crystal size. ### Claim 2 (depends on 1) The method of claim 1, further comprising: forming a cover sheet from the glass-ceramic part; applying a mask to the first region; disposing a display adjacent to the second region; affixing the cover sheet to a housing of an electronic device; wherein: the first region has an optical haze; applying the mask conceals the optical haze; and the second region is optically transparent such that information presented on the display is free of haze induced by the cover sheet. ### Claim 3 (depends on 1) The method of claim 1, wherein the second temperature is below the crystallization temperature of the glass part. ### Claim 4 (depends on 1) The method of claim 1, wherein: the second region is optically transparent; and the first region comprises an optical haze. ### Claim 5 (depends on 1) The method of claim 1, wherein heating the first region is performed by at least one of a laser or a furnace. ### Claim 6 (depends on 1) The method of claim 1, wherein maintaining the second region at the second temperature comprises removing heat from the second region using a heat sink. ### Claim 7 (depends on 1) The method of claim 1, wherein maintaining the second region at the second temperature comprises shielding the second region from a heat source. ### Claim 8 A method for forming a glass-ceramic part comprising: heating a first region of a glass part to a first temperature that is at or above a nucleation temperature of the glass part; maintaining a second region of the glass part at or below a second temperature that is below the first temperature; and subsequently heating the first region of the glass part to a third temperature that is at or above a crystallization temperature of the glass part, thereby converting the glass part to the glass-ceramic part, such that: the first region has a first crystal density; and the second region has a second crystal density that is less than the first crystal density. ### Claim 9 (depends on 8) The method of claim 8, wherein the second temperature is below the nucleation temperature of the glass part. ### Claim 10 (depends on 8) The method of claim 8, wherein: the first region has a first median crystal size; and the second region has a second median crystal size that is less than the first median crystal size. ### Claim 11 (depends on 8) The method of claim 8, further comprising maintaining the second region of the glass part at or below the third temperature while the first region is heated at least to the third temperature. ### Claim 12 (depends on 11) The method of claim 11, wherein the second crystal density is zero. ### Claim 13 (depends on 8) The method of claim 8, further comprising applying a low-emissivity coating to the second region. ### Claim 14 (depends on 8) The method of claim 8, further comprising applying a conductive coating to the first region. ### Claim 15 An electronic device comprising: a display; a housing; a cover sheet affixed to the housing and positioned adjacent to the display, the cover sheet comprising: a first region having an optical haze and a first median crystal size; and a second region having a second median crystal size that is smaller than a crystal size that causes scattering of light. ### Claim 16 (depends on 15) The device of claim 15, further comprising: a processor configured to provide information for presentation on the display; a mask at least partially surrounding a periphery of the display; wherein: the cover sheet is positioned adjacent to the display; the first region is adjacent to the mask such that the mask conceals the optical haze; and the second region is adjacent to the display such that the information presented on the display is free of haze induced by the cover sheet. ### Claim 17 (depends on 16) The device of claim 16, wherein the mask is formed from an opaque ink. ### Claim 18 (depends on 15) The device of claim 15, wherein a strength of the first region is greater than a strength of the second region. ### Claim 19 (depends on 15) The device of claim 15, further comprising at least one camera positioned adjacent to the second region of the display such that images captured by the camera are free of haze induced by the cover sheet. ### Claim 20 (depends on 15) The device of claim 15, wherein the cover sheet comprises an opening for at least one of a button or a speaker.