PATENT DOCUMENT

Publication Number: US-9718249-B2
Application Number: US-201213679493-A
Country: US
Kind Code: B2

Title: Laminated aluminum oxide cover component

Abstract:
A cover glass for an electronic display comprises a plurality of layers of sapphire material, each of the layers having a substantially single crystal plane orientation, with adjacent layers having different substantially single crystal plane orientations. One or more interface layers are defined between adjacent layers of the sapphire material, with the adjacent layers of sapphire material bonded together at the one or more interface layers. A display window is defined in the cover glass, and configured for viewing a viewable area of the electronic display through the plurality of layers of the sapphire material bonded together at the one or more interface layers.

Claims:
I claim: 
     
       1. A cover glass for an electronic display, the cover glass comprising:
 a plurality of sapphire sheets directly bonded together by hydrogen bonds at a planar interface between adjacent sapphire sheets; and 
 a display window defined in the cover glass, the display window configured for viewing the electronic display through the plurality of sheets of substantially single crystal sapphire; wherein 
 each of the sapphire sheets has a substantially single crystal plane orientation; and 
 adjacent sapphire sheets have different crystal plane orientations. 
 
     
     
       2. The cover glass of  claim 1 , wherein the adjacent sapphire sheets have substantially orthogonal crystal plane orientations. 
     
     
       3. The cover glass of  claim 2 , wherein the adjacent sapphire sheets comprise alternating A plane and C plane orientations. 
     
     
       4. The cover glass of  claim 1 , further comprising a metal component in one or more of the sapphire sheets, the metal component selected for one or more physical properties including color, hardness, and thermal or electrical conductivity and resistivity. 
     
     
       5. The cover glass of  claim 1 , further comprising a display window layer comprising substantially opaque window border portions and a substantially transparent window portion configured to define the display window in the cover glass. 
     
     
       6. The cover glass of  claim 5 , wherein the display window layer is provided between two of the plurality of sapphire sheets. 
     
     
       7. A device comprising:
 a display; 
 a frame disposed about the display; 
 a back cover coupled to a back of the frame and positioned behind the display; 
 a front glass coupled to a front of the frame and positioned in front of the display, the front glass comprising a plurality of sapphire sheets directly bonded together by hydrogen bonds at a planar interface between adjacent sapphire sheets; wherein 
 each of the sapphire sheets has a substantially single crystal plane orientation; 
 the crystal plane orientations of adjacent sapphire sheets are different; and 
 a substantially transparent display window is defined in the front glass for viewing the display through the plurality of sapphire sheets. 
 
     
     
       8. The device of  claim 7 , further comprising a display layer disposed between two of the plurality of sapphire sheets, the display layer comprising opaque border portions and a transparent window portion defining the display window in the front glass. 
     
     
       9. The device of  claim 7 , wherein the adjacent sapphire sheets have substantially orthogonal crystal plane orientations at the one or more planar interface layers. 
     
     
       10. The device of  claim 7 , wherein the back cover comprises a back cover glass formed by bonding two or more layers of substantially single crystal sapphire together across a planar interface, wherein the planar interface defines a transition between different crystal plane orientations in the two or more layers of substantially single crystal sapphire. 
     
     
       11. A cover glass for an electronic device having a display, the cover glass comprising:
 a first sapphire sheet having a first substantially single crystal plane orientation; 
 a second sapphire sheet having a second substantially single crystal plane orientation, the second crystal plane orientation substantially orthogonal to the first crystal plane orientation; 
 an interface layer defined between the first and second sapphire sheets, bonding the first and second sapphire sheets together at a planar interface by fusing non-single crystal aluminum oxide to the first and second sapphire sheets; 
 a third sapphire sheet adjacent the second sapphire sheet; and 
 a display window defined in part by an opening in a mask that is positioned between the second sapphire sheet and the third sapphire sheet, the display window configured for viewing the display through the first and second sapphire sheets bonded together across the interface layer. 
 
     
     
       12. The cover glass of  claim 11 , further comprising a display window layer adjacent the second sapphire sheet, the display window layer comprising substantially opaque side regions and a substantially transparent window region configured for viewing a viewable area of the display through the cover glass. 
     
     
       13. The cover glass of  claim 11 , wherein the first, second and third sapphire sheets each have a thickness of about 0.2 mm to about 0.4 mm, and wherein the cover glass has a thickness of 1.0 mm or less. 
     
     
       14. The cover glass of  claim 1 , wherein the crystal plane orientations of the plurality of sapphire sheets are selected for one or more physical properties, including at least one of hardness, durability, impact resistance, and scratch resistance. 
     
     
       15. The cover glass of  claim 1 , further comprising a coating over a surface of one of the plurality of sapphire sheets, the coating comprising at least one of an optical coating, a scratch coating, an abrasion coating, an anti-reflection coating, an anti-glare coating, a photochromatic coating, and an olephobic coating. 
     
     
       16. The cover glass of  claim 2 , wherein the adjacent sapphire sheets comprise alternating M plane and C plane orientations. 
     
     
       17. The device of  claim 7 , wherein at least a portion of the front glass is configured for capacitive touch-sensing across a surface of the front glass. 
     
     
       18. The device of  claim 7 , wherein the front glass is coupled to the frame by at least one of an adhesive layer and a mechanical attachment. 
     
     
       19. The cover glass of  claim 11 , wherein the interface layer is formed by heating the first and second sapphire sheets and the non-single crystal aluminum oxide to between 2000° C. and 2100° C. and placing the first and second sapphire sheets under compressive stress. 
     
     
       20. The cover glass of  claim 11 , wherein the first sapphire sheet comprises an A plane orientation and the second sapphire sheet comprises a C plane orientation.

Description:
TECHNICAL FIELD 
     This subject matter of this disclosure relates generally to display and cover glass components for electronic devices. In particular, the disclosure relates to laminated materials suitable for use in display and cover glass components for electronic devices, including, but not limited to, cellular phones, tablet computers, personal computers, personal digital assistants, media players, and other stationary and portable electronic devices. 
     BACKGROUND 
     Electronic devices generally include a variety of different display and cover components, including front and back glasses (or cover glasses), display windows, touch screens, track pads, camera and lens covers, and other internal and external cover components where optical features, durability and reliability are design issues. In use, these components are subject to a wide range of different environmental effects, including physical and electrical contact, temperature extremes, scratching, and impact. 
     These effects raise a number of design issues, particularly where internal and external components are subject to different combinations of environmental conditions and performance requirements. Associated design and engineering considerations include tradeoffs between shock and impact resistance, machinability, temperature stability, and thermal and electromagnetic properties including resistance, conductance, and permeability. 
     SUMMARY 
     This disclosure relates to cover glass and display components for electronic devices, methods of making the cover glass, and electronic devices incorporating the cover glass and display components. In various examples and embodiments, the cover glass includes a plurality of layers of substantially single-crystal sapphire, each of the layers having a substantially single crystal plane orientation, with adjacent layers having different orientations. One or more interface layers are defined between adjacent sapphire layers, bonding the layers together. A display window is defined in the cover glass, and configured for viewing the electronic display through the sapphire and interface layers. 
     Depending on configuration, the adjacent layers of substantially single crystal sapphire may have substantially orthogonal crystal plane orientations, for example alternating A and C plane orientations defined substantially along the one or more interface layers. One or more of the sapphire layers may also include a metal component selected for physical properties including color, hardness, thermal or electrical conductivity and resistivity, and magnetic permeability. 
     The cover glass may include a display window layer comprising substantially opaque border portions and a substantially transparent window portion configured to define the display window in the cover glass. The display window layer can be provided between two of the layers of substantially single-crystal sapphire material, or in a top or bottom layer of the cover glass. 
     The one or more interface layers may define adhesive bonds or hydrogen bonds between the adjacent sapphire layers. Alternatively, the one or more interface layers may be fused together across the one or more interface layers, for example by fusing a polycrystalline or amorphous aluminum oxide material between the adjacent sapphire layers. Depending on manufacturing method, the cover glass can be formed by compressively loading the adjacent sapphire layers during thermal fusion, for example at a fusion temperature between about 2000° C. and about 2100° C. 
     In additional configurations, an electronic device includes a display, a frame disposed about the display, a back cover coupled to a back of the frame and positioned behind the display, and a front glass coupled to a front of the frame and positioned in front of the display. The front glass is formed by bonding together a plurality of sapphire layers having substantially single crystal plane orientations, where the crystal plane orientations of adjacent layers are different. 
     A substantially transparent display window is defined in the front glass, and configured for viewing the display through the plurality of sapphire layers. For example, the device may include a display layer disposed between two of the sapphire layers, where the display layer includes substantially opaque side portions and a substantially transparent window portion to define the display window in the front glass. 
     One or more interface layers may be defined between the adjacent sapphire layers, for example with the sapphire layers bonded together across the interface layers, or with adjacent sapphire layers having substantially orthogonal crystal plane orientations along the interface layers. The interface layers may also include a polycrystalline or substantially amorphous aluminum oxide material fused between the adjacent sapphire layers, or hydrogen bonds between the adjacent sapphire layers. 
     The back cover of the device can also be formed by bonding two or more substantially single crystal sapphire layers together along an interface. The interface defines a transition between different crystal plane orientations in the two or more sapphire layers. 
     Alternatively, a cover glass for an electronic device with a display may include at least first and second sapphire layers having first and second substantially orthogonal single crystal plane orientations, bonded together across an interface layer. A display window can be defined in the cover glass, configured for viewing the display through the first and second sapphire layers bonded together across the transition layer. 
     Depending on application, the interface layer may define a fusion bond between the first and second sapphire layers. A display window layer may be provided adjacent the second sapphire layer, with substantially opaque side regions and a substantially transparent window region configured for a viewing the display through the cover glass. 
     The cover glass can include a third sapphire layer adjacent the display window layer, opposite the second sapphire layer, so that the display window layer is between the second and third sapphire layers. The first, second and third sapphire layers may each have a thickness of about 0.2 mm to about 0.4 mm, with a cover glass thickness of 1.0 mm or less. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of an electronic device in a communications embodiment, showing the front cover glass. 
         FIG. 1B  is an alternate perspective view of the device, showing the back cover glass. 
         FIG. 2A  is a perspective view of the electronic device in an alternate configuration, showing the front glass. 
         FIG. 2B  is a rear view of the electronic device, showing the back cover. 
         FIG. 3A  is a front perspective view of the electronic device in a media player embodiment, showing the display window. 
         FIG. 3B  is a front perspective view of the electronic device in a tablet computer embodiment. 
         FIG. 4  is a block diagram illustrating internal and external components of the electronic device. 
         FIG. 5  is a cross-sectional view of the electronic device, taken along line A-A of  FIG. 3B . 
         FIG. 6A  is a cross-sectional view of a representative cover glass for the electronic device, illustrating the laminar structure. 
         FIG. 6B  is a schematic view of representative crystal plane orientations for the layers of the laminar cover glass. 
         FIG. 7A  is a cross-sectional view of the cover glass, illustrating a first alternate laminar structure. 
         FIG. 7B  is a cross-sectional view of the device and cover glass, illustrating a second alternate laminar structure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  is a perspective view of electronic device  10  in a communications embodiment, for example a portable phone or digital assistant, showing front cover (or cover glass)  12 A.  FIG. 1B  is an alternate perspective view of device  10 , showing rear cover (or cover glass)  12 B. 
     As shown in  FIGS. 1A and 1B , device  10  includes front cover or cover glass  12 A with display window  14 , back cover or cover glass  12 B, and housing  16 . These components of device  10  may also be configured for a range of different electronics applications, including not only portable phones, digital assistants and other communications devices, as illustrated in  FIGS. 1A and 1B , but also personal computers, tablet computers, computer displays, media players, and other portable and stationary electronic devices. 
     In this particular configuration, front cover glass  12 A and rear cover glass  12 B are coupled to housing  16  using a bezel or frame assembly  18 . One or both of front and rear cover glasses  12 A and  12 B incorporate a laminated aluminum oxide, sapphire crystal, or sapphire glass material, providing a range of different performance features including scratch and impact resistance, durability, and increased surface hardness, as described below. 
     Display window  14  is configured for viewing a display through front cover glass  12 A, for example as defined between top and bottom (or side) border regions  15 . Depending on configuration, display window  14  may also accommodate one or more interactive control features, for example an internal or external touch screen or touch-sensitive display, with capacitive or resistive coupling across the front surface of cover glass  12 A. 
     Cover glasses  12 A and  12 B may also include or accommodate additional features, including, but not limited to, additional control features  20  (e.g., a home button or other control device), audio features  22  (e.g., a speaker or microphone), sensors  24 A and  24 B (e.g., cameras or infrared sensors), and lighting or indicator features  26  (e.g., a flash unit, light emitting diode or other indicator, display or illumination device). Depending on design requirements, additional cover glass components may be provided for one or more of these features, for example a separate lens cover glass element  12 C for camera  24 B, as provided within back cover glass  12 B. 
     Housing  16  and frame  18  are typically formed of durable polymer, composite, or metal materials, for example a metal or metal alloy such as aluminum or stainless steel, or a durable plastic or composite material. Housing  16  and frame  18  may also be provided as substantially unitary or discrete components, for example bottom housing  16 A and top housing  16 B in combination with a unitary bezel or frame assembly  18 , or in other configurations, as described below. 
     Housing  16  and frame  18  may also be configured to accommodate additional accessory features, including, but not limited to, additional speaker or microphone apertures  28 , one or more connector apertures  30  for power, audio (e.g. earphone), and control connections, mechanical fasteners or coupling points  32 , and one or more access ports  34  (e.g, for a subscriber identity module, flash memory device, or other internal component). These features may be variously arranged on front and back covers  12 A and  12 B, and on the individual components of housing  16 , for example along bottom housing  16 A or top housing  16 B, or on discrete side housing or back cover structures, as described below. 
       FIG. 2A  is a perspective view of electronic device  10  in an alternate configuration, for example an advanced portable device or smart phone, showing front glass  12 A with display window  14 .  FIG. 2B  is an rear view of device  10 , showing back glass  12 B provided as one or more discrete inlays or inset components  12 D, with or without a separate cover glass element  12 C for sensor elements such as back camera  24 B. 
     As shown in  FIGS. 2A and 2B , device  10  is adaptable to a range of different front and back cover glass and housing configurations. In this particular embodiment, for example, housing  16  includes bottom housing  16 A and top housing  16 B in a beveled configuration, with beveled side housing sections  16 C coupled across middle plate  16 D, forming the back surface of device  10  between back glass components  12 D. 
     Front and back glass components  12 A and  12 B (or  12 D) also accommodate range of different arrangements and configurations for display window  14 , accessory and control features  20 , audio features  22 , camera or sensor features  24 A and  24 B, and lighting or indicator features  26 , as shown in  FIGS. 2A and 2B . Device  10  may also include additional control or accessory features, for example one or more volume, ringer, mute, or hold buttons or switches  20 A,  20 B and  20 C,  20 D, for examples as provided in bottom housing  16 A, top housing  16 B, or side housing  16 C, one or more of cover glass components  12 A,  12 B, and  12 D, or a combination thereof. 
       FIG. 3A  is a front perspective view of electronic device  10 , in a media player embodiment, showing display window  14  in front glass  12 B. As illustrated in  FIG. 3A , the various horizontal and vertical orientations of device  10  are arbitrary, and designations of the various top, bottom, and side components may be interchanged without loss of generality. 
     As shown in  FIG. 3A , housing  16  may have a substantially unitary configuration, for example with housing  16  formed together with the back cover of device  10 . Front glass  12 A may be also attached to housing  16  via adhesive coupling to frame  18 , and one or both of housing  16  and frame  18  may be formed of a plastic or other durable polymer material rather than metal, or using a combination of metal, polymer or plastic, and composite materials. 
       FIG. 3B  is a front perspective view of electronic device  10 , in a computer embodiment, for example a tablet computer, pad computer, or other computing device, or a computer monitor or display. Front glass  12  can be configured to accommodate display window  14 , a hold button or other control feature  20 , and one or more other accessory features, provided in a variety of different arrangements as described above. As shown in  FIG. 3B , housing  16  may also be coupled to front glass  12 A with a substantially internal frame assembly  18 , as described above, or via a bezel or groove arrangement  18 A formed into housing  16 , or using a combination of the two. 
       FIG. 4  is a block diagram of electronic device  10 , illustrating internal and external components. Device  10  encompasses a range of different portable and stationary electronics applications for cover glass  12 , as described above, including hybrid devices such as a mobile telephone and computing devices with media player capabilities, remote controls and game players, global positioning and telecommunications devices, and laptop, desktop, notebook, handheld or ultraportable computer and monitor display devices. 
     Cover glass  12  incorporates a laminated sapphire, crystalline aluminum oxide or sapphire glass construction, as configured for improved hardness, durability, impact and scratch resistance or other performance features selected for the particular characteristics of electronic device  10 . Particular examples of cover glass  12  include, but are not limited to, front glass  12 A, back glass  12 B, specialty (e.g., camera or lens) cover glass  12 C, or a glass insert, inset or inlay element  12 D, as described above. 
     Depending on embodiment, cover glass  12  may include display window  14  and one or more additional control features  20 , including button-type control features  20  as well as volume, ringer, and hold switches, buttons and other control features  20 A,  20 B,  20 C, or  20 D, and additional accessory features  24  including cameras (e.g., camera features  24 A or  24 B). Accessories  24  may also include audio features (e.g., microphone or speaker features  22  and  28 ), and audio/visual features (e.g., flash or indicator/display features  26 ). 
     Device  10  may also include a range of different internal components, for example a controller  42  including a microprocessor (μp), memory, and one or more input/output (IO) and interface components. Controller  42  is coupled to display  43 , as provided within display window  14  of cover glass  12 . 
     Additional sensor and internal accessory components  44  may also be provided, for example an accelerometer or motion sensor, or a haptic feedback device such as a vibration motor or actuator. External connections can be made to additional components via hard-wired connectors  30 A or wireless connections  30 B, including, but not limited to, headphones, speakers, displays and other external components  45 . Device  10  may also be connected to a host device  46  and one or more networks  47 , for example a wireless communications network, a local area network, or the internet. 
     Processor, memory, and input-output (or control) components  42  are configured to operate electronic device  10  and communicate with external components  45 ,  46 , and  47 . Control components  10  may execute operating system and application software to provide a range of functions including, but not limited to, voice communications, internet browsing, messaging, email, media playback and development, gaming, security, transactions, navigation, and scheduling, reminders, alarms, and other personal digital assistant and portable or fixed electronics device functions. Control components  10  also include communications interface and other input-output (IO) elements to support hard-wired, audio (e.g., voice control), and wireless communications, including infrared (IR), visual, and radio frequency (RF) communications. 
       FIG. 5  is a cross-sectional view of electronic device  10 , for example as taken along line A-A of  FIG. 3B , or for any of the other devices  10  as shown in  FIGS. 1A, 1B, 2A, 2B, 3A , and  4 . In the particular configuration of  FIG. 5 , device  10  comprises front glass  12 A, back glass  12 B, housing  16  with side housings  16 C, and frame  18 . Internal components of device  10  include controller  42 , display  43  and battery or other power source  49 . 
     Front glass  12 A and back glass  12 B are coupled to side housings  16 C via mechanical attachment to frame  18 . Controller  42 , display  43  and battery  49  are disposed within housing  16  and frame  18 , with frame  18  disposed about the periphery of display  43 . Front glass  12 A is coupled to the back (or bottom) portion of frame  18 , and positioned behind (or below) display  43 . Front cover glass  12 A is coupled to the front (or top) portion of frame  18 , and positioned in front of (or above) display  43 . 
     One or both of front glass  12 A and back glass  12 B are formed of a plurality of substantially single crystal sapphire layers, each having a substantially single crystal plane orientation. The sapphire layers are bonded together to form front glass  12 A or back glass  12 B, or both. The substantially single crystal plane orientations of adjacent sapphire layers are different, in order to provide improved stress and strain characteristics as described below. 
     Display window  14  is defined in front glass  12 A, and configured for viewing display  43 . Typically, display window  14  is provided as a substantially transparent feature, in order to observe a viewable area of display  43  through the layers of front glass  12 A. Substantially opaque side or border portions  15  may also be provided, in order to define the boundaries of transparent display window  14 . Back glass  12 B may be substantially opaque or transparent, and may also include one or more display windows  14 , for example to view an additional back-side display or indicator, or another internal component of electronic device  10 . 
       FIG. 6A  is a cross-sectional view of cover glass  12  for an electronic device, illustrating a laminar single-crystal layer structure, for example with one, two, three or more single-crystal layers  50 A,  50 B, and  50 C, bonded together at interface layers  51 . Additional surface coatings  52  and  53  may also be provided, for example one or more of an optical coating, a scratch or abrasion coating, an anti-reflection or anti-glare coating, a photochromatic coating, a pigmented coating, and an olephobic or other moisture or oil-resistant coating. 
     In the particular example of  FIG. 6A , layers  50 A,  50 B, and  50 C of cover glass  12  are formed of an aluminum oxide, sapphire, or sapphire glass material, where each layer  50 A- 50 C has a substantially single-crystal configuration, bonded together by fusion, adhesion, or other bonding process across interface layers  51 . The substantially single crystal plane orientations of each individual layer  50 A,  50 B, and  50 C vary, with different plane orientations selected in adjacent sapphire layers for a combination of strength, hardness, durability, scratch resistance, and ability to withstand shock, impact, thermal variation, and other stress and strain effects. 
     As used herein, the term “sapphire glass” encompasses sapphire and aluminum oxide materials in substantially single-crystal or polycrystalline form, for example corundum, sapphire, or ruby, and in fused polycrystalline or amorphous forms. Similarly, the terms “glass” and “cover glass” encompass single-crystal, polycrystalline, fused polycrystalline and amorphous sapphire, corundum and aluminum oxide materials, and components made from these materials. 
     In particular, the term “glass” as used herein is not limited to amorphous forms, for example amorphous silica glass. This reflects usage in the art, and in this disclosure, where cover glasses, front glasses, back glasses, glass inlays, glass insets, glass inserts, and other glass components may be described as glass elements or glass components, whether provided in amorphous, polycrystalline, fused polycrystalline, or substantially crystalline form, and whether formed of aluminum oxide and sapphire materials, as described herein, or whether formed of silica glass, lead crystal, quartz, or other materials, as known in the art. 
     In general, sapphire, sapphire glass, and aluminum oxide materials provide layers  50 A,  50 B, and  50 C with increased hardness and strength, as compared to other glass materials including silica glass. In addition, the different crystal plane orientations of individual sapphire layers  50 A,  50 B, and  50 C provide particular combinations of stress and strain resistance, depending on the crystal plane orientations of adjacent layers  50 A,  50 B, and  50 C. 
     Substantially single-crystal sapphire layers  50 A- 50 C are formed by sintering and fusing aluminum oxide (alumina; Al 2 O 3  or α-Al 2 O 3 ) in an inert atmosphere to produce a single crystal (or substantially single crystal) sapphire or corundum boule. Typical synthesis processes include, but are not limited to, Verneuil processes, Czochralski processes, and flux methods. The sapphire boules are then cut (e.g., using industrial diamond saws) to produce single-crystal sheets or blanks, with individual layer thickness from about 0.2 mm to about 1.0 mm, for example about 0.2 mm-0.4 mm or about 0.3 mm, or about 0.3-0.5 mm, about 0.4 mm-0.6 mm, or about 0.5 mm-1.0 mm. 
     Two, three, four or more individual single-crystal sapphire layers  50 A- 50 C may be bonded together by fusion processes to form cover glass  12 , for example by heating with individual layers  50 A- 50 C under compressive load. The melting point of sapphire is approximately 2030-2050° C., and suitable bonding temperatures may range from about 2000° C. to about 2100° C., depending on loading properties and desired fusion time and bond configuration. 
     In fused embodiments of cover glass  12 , interface layer  51  may be formed as a substantially amorphous or polycrystalline sapphire glass or aluminum oxide layer, as defined between adjacent substantially single-crystal layers  50 A,  50 B, and  50 C. For example, interface layer  51  may be formed by providing a polycrystalline or amorphous aluminum oxide material between two adjacent substantially single-crystal sapphire layers  50 A- 50 C, and bonding the adjacent substantially single-crystal sapphire layers together across interface layer  51  by thermal fusion. Alternatively, interface layer  51  may be formed by thermal fusion of adjacent substantially single-crystal sapphire layers  50 A- 50 C, without the addition of additional aluminum oxide or other materials. 
     In additional examples, hydrophilic (OH) surfaces may be formed on adjacent single-crystal layers  50 A- 50 C, in order to provide hydrogen bonding along interface layers  51 . Interface layers  51  can also be formed as adhesive bonded layers, for example using a polymer binder or other adhesive material, or as an optical coating, pigment, or other surface coating, as described above. Alternatively, adjacent layers  50 A,  50 B, and  50 C may be bonded by a cold working process layer  51 , or layers  50 A,  50 B, and  50 C may be maintained in an adjacent relationship by mechanical coupling along interfaces  51 , for example a compressive coupling along the edges of cover glass  12 . 
       FIG. 6B  is a schematic diagram illustrating the crystal plane orientation of aluminum oxide (sapphire or corundum) crystal  54 , for example in a substantially single-crystal sapphire or ruby embodiment. As shown in  FIG. 6B , sapphire  54  exhibits a multi-faceted (e.g., rhombohedral) crystal structure, with individual crystal planes oriented at different relative angles, including, but not limited to, crystal planes N, C, R, A, and M, respectively. 
     The angular orientations of the different crystal planes may be defined in terms of perpendicular vectors, for example angle θ NC  of about 61° between perpendiculars [n] and [c] to planes N and C, and angle θ CR  of about 57.6° between perpendiculars [c] and [r] to planes C and R, respectively. Additional planar orientations are also shown in  FIG. 6B , including angle θ RM  of about 32.4° between perpendiculars [r] and [m] to planes R and M, and angle θ MA  of about 30° between perpendiculars [m] and [a] to planes M and A, respectively. Some planes have substantially perpendicular orientations, for example planes A and C and planes M and C, but the relationship is not necessarily mutual or transitive; that is, plane A is perpendicular to plane C, and plane C is perpendicular to plane M, but plane M is not perpendicular to plane A, as shown in  FIG. 6B . 
     In assembling laminar cover glass  12 , different crystal planes N, C, R, A, and M (and other planar orientations) are selected for stress and strain properties, inherent strength, and scratch, impact and shock resistance. In one particular application, for example, cover glass  12  may incorporate alternating substantially single-crystal A and C (or C and A) planes, oriented along the substantially parallel surfaces of sapphire layers  50 A,  50 B, and  50 C, respectively. In this embodiment, crystal planes A and C may be selected not only for inherent planar strength, but also based on the resulting perpendicular crystal plane structures, as defined at or across interface layers  51 . 
     Alternating M and C planes may also be utilized, or any combination of A, M, and C, planes, where inherent planar strength varies but each interface  51  is formed at a perpendicular crystal plane interface  51 . In additional examples, any other combination of crystal plane orientations N, C, R, A, and M may be used for layers  50 A- 50 C, in any order, with a variety of different perpendicular and skew crystal plane intersections defined along interface layers  51 . 
       FIG. 7A  is a cross-sectional view of cover glass  12 , illustrating an alternate laminar structure. In this configuration, cover glass  12  is formed of four or more substantially single-crystal sapphire or aluminum oxides layers  50 A- 50 D, with different crystal plane structures for improved strength, impact and scratch resistance, and selected stress and strain properties, as described above. 
     Individual single-crystal sapphire layers  50 A- 50 D may be fusion bonded, adhesive bonded, or mechanically bonded to form cover glass  12 , as described above. Correspondingly, interface layers  51  may be formed as substantially polycrystalline sapphire or amorphous aluminum oxide interfaces  51  between adjacent sapphire layers  50 A- 50 D, or as adhesive or mechanically bonding interfaces  51 . Various top and bottom coatings  52  and  54  may also be applied to cover glass  12 , including optical, oleophobic, hydrophobic, and protective coatings, as described above. 
     Sapphire layers  50 A- 50 D may also be doped or implanted with a range of different materials to provide desired physical properties, including, but not limited to, color, density, hardness, thermal or electrical conductivity and resistivity, and magnetic permeability or reluctance. In particular, any one or more of single-crystal sapphire layers  50 A- 50 D may include one or more iron, titanium, chromium, copper, magnesium or other metal components, dopants, or impurities, in order to provide a desired tint or color cast, such as red, orange, yellow, green, blue, violet or purple, or a combination thereof. Where chromium impurities are present, for example, sapphire layers  50 A- 50 D may also be referred to a ruby layers, and cover glass  12  may be referred to as a ruby glass or ruby cover glass component. 
     One or more pigmentation layers  55  may also be provided, for example as an internal pigmentation layer between any two sapphire layers  50 A- 50 D, as shown in  FIG. 7A , or as an external pigmented coating layer  52  or  53 . Pigmentation layers  55  may be provided with a range of (e.g., substantially opaque) colored materials, for example red, yellow, blue, cyan, magenta, black and white, and combinations thereof, in order to shield internal components of the electronic device from external radiation (e.g., infrared sensors, cameras, and other light or radiation-sensitive components). 
     Where pigmentation layers  55  are provided as internal layers between two sapphire layers  50 A- 50 D, scratching and abrasion are reduced during shipping, assembly and use. Internal pigmentation layers  55  may also include additional coating materials, for example adhesives and conducting or resistive materials, for example to provide electrical or capacitive coupling to a touch screen or other touch-sensitive device, or to provide shielding from radio frequency radiation. 
       FIG. 7B  is a cross-sectional view of device  10  with front (or top) cover glass  12 A and back (or bottom) cover glass  12 B, illustrating an alternate laminar structure configured to define display window  14  for with display  43 . In this configuration, cover glass  12  is formed of three or more substantially single-crystal sapphire or aluminum oxides layers  50 A- 50 C separated by various interface layers  51 , with or without additional surface coating layer  52  and  53 , as described above. 
     In addition, cover glass  12  includes window layer  56  between one or more upper sapphire layers  50 A- 50 B and one or more lower sapphire layers  50 C. Window layer  56  is configured to provide display window area  14  for display  43 , for example a touch-screen or touch-sensitive (interactive) display module, as described above. 
     Display window layer  56  includes side or border regions  56 A and window or viewing region  56 B. Side regions  56 A may be substantially opaque, for example comprising substantially opaque pigmentation layers or deeply colored ruby or sapphire layers, as described above. Display window region  56 B may be substantially transparent, for example a substantially transparent single-crystal sapphire or lightly tinted aluminum oxide material. Alternatively, window region  56 B of display window layer  56  may be provides as a substantially uncoated region between borders  56 B, or a clear coating region between borders  56 B. 
     Generally, display window region  56 B is configured to define to a substantially transparent display window  14  in cover glass  12 A, with border portions  56 A selected to define the viewing area of display  43 . Alternatively, the geometry of border regions (or portions)  56 A and window region (or portion)  56 B may vary with respect to one or both of display window  14  and display  43 , depending on the desired configuration of cover glass  12 A. Display window  14  may also be defined by a bottom pigmented layer  53 , with substantially opaque side regions  53 A configured to accommodate the viewing area of display  43 . 
     While this invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof, without departing from the spirit and scope of the invention. In addition, modifications may be made to adapt the teachings of the invention to particular situations and materials, without departing from the essential scope thereof. Thus, the invention is not limited to the particular examples that are disclosed herein, but encompasses all embodiments falling within the scope of the appended claims.

Metadata:
Filing Date: 20121116
Publication Date: 20170801
Grant Date: 20170801
Priority Date: 20121116
Inventors: KWONG KELVIN
Assignee: APPLE INC
CPC Classifications: [{"code": "C30B29/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/24322", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/24322", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/0202", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/24331", "inventive": false, "first": false, "tree": "[]"}, {"code": "C30B29/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "C30B33/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/24331", "inventive": false, "first": false, "tree": "[]"}, {"code": "C30B33/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0202", "inventive": true, "first": false, "tree": "[]"}, {"code": "B32B3/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04M1/0202", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/24331", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B3/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T428/24322", "inventive": false, "first": false, "tree": "[]"}, {"code": "C30B33/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "C30B29/20", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 49620266