PATENT DOCUMENT

Publication Number: US-9223349-B2
Application Number: US-201213528789-A
Country: US
Kind Code: B2

Title: Low-force dust seal

Abstract:
An electronic device may have polarizer layers, color filter layers, thin-film-transistor layers, and other display layers. A display layer may be separated from structures such as a display cover layer formed from clear glass or plastic and a touch sensor layer mounted on an inner surface of the display cover layer by an air gap. Cavities within an electronic device housing may serve as a source of dust and other contaminants. The air gap may be sealed against dust intrusion from a cavity within an electronic device using a dust sealing structure. The dust sealing structure may have a rectangular ring shape that runs around a rectangular peripheral portion of a display layer. The dust sealing structure may be formed from a tape-based structure, an elastomeric structure, a compressible foam structure, or a cured liquid structure.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a display layer; 
 a structure that is separated from the display layer by an air gap; and 
 a tape-based dust seal that is configured to span the display layer and the structure to seal the air gap against dust intrusion, wherein the display layer comprises a color filter layer, and wherein the tape-based dust seal is attached to the color filter layer. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the structure comprises a housing structure. 
     
     
       3. The electronic device defined in  claim 2  wherein the tape-based dust seal comprises a strip of tape having one portion that is attached to the housing structure and another portion that is attached to the display layer. 
     
     
       4. The electronic device defined in  claim 3  wherein the strip of tape has an S-shaped cross-sectional shape. 
     
     
       5. The electronic device defined in  claim 1  wherein the tape-based dust seal comprises a strip of tape with a C-shaped cross-sectional shape. 
     
     
       6. The electronic device defined in  claim 1  wherein the structure comprises a display cover layer. 
     
     
       7. The electronic device defined in  claim 6  wherein the tape-based dust seal comprises a strip of tape having one portion that is attached to the color filter layer and another portion that is attached to the display cover layer. 
     
     
       8. An electronic device, comprising:
 a display layer; 
 a structure that is separated from the display layer by an air gap; and 
 an elongated dust seal structure that seals the air gap against dust infiltration, wherein the elongated dust seal structure comprises a foam member surrounded at least partially by a dust barrier layer that is interposed between the foam member and the display layer. 
 
     
     
       9. The electronic device defined in  claim 8  wherein the structure comprises a touch sensor layer and wherein the dust barrier layer comprises a layer of fabric. 
     
     
       10. The electronic device defined in  claim 8  wherein the dust barrier layer comprises a layer selected from the group consisting of: a plastic layer, a metal layer, and a resolidified layer of melted foam. 
     
     
       11. The electronic device defined in  claim 8  wherein the display layer comprises a color filter layer. 
     
     
       12. The electronic device defined in  claim 11  wherein the structure comprises a touch sensor layer. 
     
     
       13. The electronic device defined in  claim 11  wherein the display layer comprises a display cover layer. 
     
     
       14. The electronic device defined in  claim 8  wherein the dust barrier layer has a C-shaped cross-sectional shape. 
     
     
       15. The electronic device defined in  claim 8  wherein the dust barrier layer has an O-shaped cross-sectional shape. 
     
     
       16. An electronic device, comprising:
 a display layer; 
 a structure that is separated from the display layer by an air gap; and 
 an elastomeric dust sealing structure that seals the air gap against dust, wherein the elastomeric air sealing structure is formed from a solid elastomeric material that is configured to at least partly surround an air cavity that is at least partially interposed between a portion of the elastomeric dust sealing structure and the display layer. 
 
     
     
       17. The electronic device defined in  claim 16  wherein the solid elastomeric material comprises silicone. 
     
     
       18. The electronic device defined in  claim 16  wherein the solid elastomeric material has a Shore A hardness of less than 70. 
     
     
       19. The electronic device defined in  claim 16  wherein the elastomeric dust sealing structure has a C-shaped cross-sectional shape having a first portion that contacts the display layer and having a second portion that contacts the structure. 
     
     
       20. The electronic device defined in  claim 16  wherein the elastomeric dust sealing structure has a rectangular ring shape. 
     
     
       21. The electronic device defined in  claim 20  wherein the display layer comprises a color filter layer. 
     
     
       22. The electronic device defined in  claim 21  wherein the structure comprises a touch sensor layer. 
     
     
       23. The electronic device defined in  claim 16  wherein the display layer comprises a color filter layer having a rectangular periphery and wherein the elastomeric dust sealing structure has a rectangular ring shape that runs along the rectangular periphery of the color filter layer. 
     
     
       24. The electronic device defined in  claim 16  wherein the display layer comprises a color filter layer, the electronic device further comprising a polarizer layer on the color filter layer, wherein the elastomeric dust sealing structure has a first portion that contacts the color filter layer, a second portion that contacts the polarizer layer, and a third portion that contacts the structure. 
     
     
       25. The electronic device defined in  claim 24  wherein the structure comprises a touch sensor layer. 
     
     
       26. The electronic device defined in  claim 16  wherein the structure comprises a touch sensor layer and wherein the elastomeric sealing structure has a C-shaped cross section with opposing portions that bear against the touch sensor layer. 
     
     
       27. The electronic device defined in  claim 16  wherein the elastomeric dust sealing structure has a rectangular ring shape that runs along a rectangular periphery of the display layer and wherein the elastomeric dust sealing structure has protruding alignment structures with holes.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to dust sealing structures in electronic devices. 
     Electronic devices such as computers and cellular telephones have displays, touch sensors, housings, and other structures. It may sometimes be desirable to form dust seals between these structures. For example, it may be desirable to form a dust seal between a touch sensor array and a display module. 
     Conventional dust sealing structures are based on foam gaskets. A satisfactory dust seal may be created when a foam gasket is compressed between a touch sensor and a display. However, a restoring force is produced by the compressed foam gasket that may tend to push apart structures in the electronic device. Variations in the flatness of device components and the separation between components may cause variations in foam compression. These variations may in turn lead to variations in the load that is impressed on device components, giving rise to a potential for light leakage and undesired stresses. 
     It would therefore be desirable to be able to provide improved seals between structures in an electronic device. 
     SUMMARY 
     An electronic device may have display structures such as polarizer layers, color filter layers, thin-film-transistor layers, and other display layers. A display layer may be separated by an air gap from structures such as a display cover layer formed from clear glass or plastic and a touch sensor layer mounted on an inner surface of the display cover layer. 
     Cavities within an electronic device housing may serve as a source of dust and other contaminants. The air gap may be sealed against dust intrusion from the cavities using a dust sealing structure. The display layer may have a rectangular periphery. The dust sealing structure may have a rectangular ring shape that runs around the rectangular periphery of the display layer. 
     The dust sealing structure may be formed from a tape-based structure. The tape-based structure may have a C-shaped cross-sectional shape, an S-shaped cross-sectional shape, or may have other cross-sectional shapes. 
     Solid (non-foam) elastomeric materials may be used in forming dust sealing structures. An elastomeric dust sealing structure may, for example, be formed from a material such as silicone. An elastomeric dust sealing structure may have a cross-sectional shape such as a C-shape that at least partly surrounds an air cavity. 
     Dust sealing structures may also be formed from compressible foam members. Initially, a foam member may have a first thickness. Following compression of the foam member between a display layer and another structure such as a touch sensor layer or a display cover layer, the thickness of the foam member may be reduced to a second thickness. Processing operations such as operations involving application of heat, application of ultrasonic signals, exposure to humid environments and other environments, and other operations may be used to set the compressed foam member in its compressed state, so that the foam member retains the second thickness without exerting outward forces that might otherwise tend to disassemble device structures. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with dust sealing structures in accordance with an embodiment of the present invention. 
         FIG. 2  is a cross-sectional side view of an illustrative electronic device with dust sealing structures in accordance with an embodiment of the present invention. 
         FIG. 3  is a cross-sectional side view of an electronic device with an illustrative C-shaped tape dust sealing structure in accordance with an embodiment of the present invention. 
         FIG. 4  is a cross-sectional side view of an electronic device with an illustrative S-shaped tape dust sealing structure in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional side view of electronic device structures that have been sealed using a foam gasket wrapped with an O-shaped dust barrier layer in accordance with an embodiment of the present invention. 
         FIG. 6  is a cross-sectional side view of electronic device structures that have been sealed with a foam gasket wrapped with a C-shaped dust barrier layer in accordance with an embodiment of the present invention. 
         FIGS. 7 ,  8 , and  9  are cross-sectional side views of display structures that have been sealed using illustrative elastomeric sealing structures in accordance with an embodiment of the present invention. 
         FIG. 10  is a top view of an illustrative dust sealing structure with positioning structures in accordance with an embodiment of the present invention. 
         FIG. 11  is a top view of the illustrative dust sealing structure of  FIG. 10  following removal of the positioning structures on the dust sealing structure in accordance with an embodiment of the present invention. 
         FIG. 12  is a side view of a portion of a dust sealing structure showing how the dust sealing structure may accommodate pressure fluctuations without breaking a seal in accordance with an embodiment of the present invention. 
         FIG. 13  is a cross-sectional side view of an illustrative injection molding tool being used to create a dust sealing structure in accordance with an embodiment of the present invention. 
         FIG. 14  is a cross-sectional side view of an illustrative dust sealing structure that is mounted on a release liner in accordance with an embodiment of the present invention. 
         FIG. 15  is a diagram showing how a sealing structure may be formed by compressing a compressible member between opposing structures and processing the compressed member to set the member in the compressed state in accordance with an embodiment of the present invention. 
         FIG. 16  is a flow chart of illustrative steps involved in forming a compressed dust sealing structure using a compressible member of the type shown in  FIG. 15  in accordance with an embodiment of the present invention. 
         FIG. 17  is a diagram showing how a dust sealing structure material may be formed from a highly cohesive material in accordance with an embodiment of the present invention. 
         FIG. 18  is a side view of an illustrative dust sealing structure material that is sufficiently viscous to form a bead of material on a surface in accordance with an embodiment of the present invention. 
         FIG. 19  is a cross-sectional side view of a portion of an electronic device showing how a dust sealing structure may be formed by dispensing a liquid sealing structure material from a nozzle in accordance with an embodiment of the present invention. 
         FIG. 20  is a flow chart of illustrative steps involved in forming a sealing structure using a curable liquid sealing structure material in accordance with an embodiment of the present invention. 
         FIG. 21  is a cross-sectional side view of display structures that have been sealed using a sealing structure before being mounted into an electronic device enclosure in accordance with an embodiment of the present invention. 
         FIG. 22  is a cross-sectional side view of an illustrative electronic device in which a curable liquid potting material has been used to form a dust sealing structure between a display and other structures in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Dust sealing structures may be formed from tape structures, from elastomeric members, from compressible materials such as polymer foams that are set in their compressed state, or from cured liquid materials (as examples). Dust sealing structures such as these may form low-force seals that do not tend to push apart device structures following assembly. 
     Low-force dust sealing structures may be used to form an environmental seal (i.e., a dust seal) between two or more adjacent structures in an electronic device. As an example, dust sealing structures may be used in forming a dust seal between a touch sensor array on a display cover glass and display structures such as liquid crystal display structures. Dust sealing structures may also be used in forming water resistant seals and other seals in an electronic device. The structures that are sealed may include housing structures, display structures, touch sensor structures, or other device structures. Illustrative configurations in which sealing structures are used to form dust seals between structures such as a touch sensor layer, a display cover layer, display layers such as polarizer layers, color filter layers, and thin-film transistor layers, housing structures, and combinations of any two or more of these structures are sometimes described herein as an example. This is, however, merely illustrative. Any suitable type of structures and, in particular, structures associated with an electronic device, may be sealed, if desired. 
     An illustrative electronic device of the type that may be provided with dust sealing structures is shown in  FIG. 1 . Electronic device  10  may be a computer such as a computer that is integrated into a display such as a computer monitor, a laptop computer, a tablet computer, a somewhat smaller portable device such as a wrist-watch device, pendant device, or other wearable or miniature device, a cellular telephone, a media player, a tablet computer, a gaming device, a navigation device, a computer monitor, a television, or other electronic equipment. 
     As shown in  FIG. 1 , device  10  may include a display such as display  14 . Display  14  may be a touch screen that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components or may be a display that is not touch-sensitive. Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. Configurations in which display  14  includes display layers that form liquid crystal display (LCD) pixels may sometimes be described herein as an example. This is, however, merely illustrative. Display  14  may include display pixels formed using any suitable type of display technology. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass or clear plastic. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16 . An opening may also be formed in the display cover layer to accommodate ports such as speaker port  18 . 
     Device  10  may have a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. 
     Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). The periphery of housing  12  may, if desired, include walls. For example, housing  12  may have a peripheral conductive member such as a metal housing sidewall member that runs around some or all of the periphery of device  10  or may have a display bezel that surrounds display  14 . Housing  12  may have sidewalls that are curved, sidewalls that are planar, sidewalls that have a combination of curved and flat sections, and sidewalls of other suitable shapes. One or more openings may be formed in housing  12  to accommodate connector ports, buttons, and other components. 
     A cross-sectional side view of electronic device structures associated with display  14  is shown in  FIG. 2 . As shown in  FIG. 2 , display  14  may include display backlight structures  20 , display layers (structures)  38 , and an associated touch sensor array such as touch sensor layer  40 . Touch sensor layer  40  (and, if desired, portions of an associated display cover layer) may be separated from display layers  38  by an air gap such as air gap  42 . A sealing structure such as dust sealing structure  44  may be used to prevent dust and other environmental contaminants from entering air gap  42  in direction  48  from cavity  46  (i.e., dust sealing structure  44  may seal air gap  42  against intrusion by dust). 
     Touch sensor layer  40  may be formed from an array of transparent conductive capacitive touch sensor electrodes such as indium tin oxide electrodes. A display cover layer such as display cover layer  50  may be mounted in electronic device housing  12  using a gasket such as gasket  52  (e.g., an elastomeric gasket, adhesive, or other suitable structures). One or more air-filled cavities such as cavity  46  may be formed between and within housing  12 , internal housing structures, and other internal structures in device  10 . Cavities such as cavity  46  may serve as a potential source of dust. Using sealing structures such as dust sealing structure  44  of  FIG. 2 , the dust and other contaminants may be prevented from intruding into display  14  between layers such as touch sensor layer  40  and display layers  38 . Sealing structures such as sealing structure  44  may also be used to form environmental seals between other structures in device  10  (e.g., between structures such as housing  12 , one or more of the layers in display  14 , touch sensor layer  40 , display cover layer  50 , etc.). 
     Display cover layer  50  may be formed from a layer of glass or plastic may be used to cover the surface of display  14  (e.g., the front face of device  10  of  FIG. 1 ). The structures of touch sensor layer  40  may be formed on the cover layer or may be formed on a touch sensor substrate such as a layer of glass or plastic. For example, the touch sensor layer may be implemented as a touch sensor array that is attached to display cover layer  50  or other layers in display  14  using adhesive or other attachment mechanisms or may be implemented as a layer that is incorporated elsewhere in display  14 . 
     Display backlight structures  20  may include a light source, a light guide plate, a reflector, and optical films. The light guide plate may be formed from a rectangular planar layer of plastic. The light source may be a light-emitting diode array or a lamp (as examples). Light that is emitted from the light-emitting diode array or lamp may be coupled into the light guide plate through the edge of the light guide plate. Light from the light source may be distributed laterally within the light guide plate throughout the display in accordance with the principal of total internal reflection. Light that scatters vertically upwards through backlight structures  20  in direction  54  may pass through display layers  38 , touch sensor array layer  40 , and display cover layer  50  and may serve as backlight that helps a viewer such as user  56  to view images on display  14 . The reflector in backlight structures  20  may be located below the light guide plate and may be used to direct light that has escaped from the light guide plate in the downwards direction back up in upwards direction  54 , thereby enhancing backlight efficiency. Optical films such as brightness enhancing films, diffusing films, and other films may be included in backlight structures  20  (e.g., above the light guide plate), if desired. 
     Display structures  38  may include liquid crystal display structures or structures associated with other suitable types of display. In an illustrative liquid crystal display configuration, a layer of liquid crystal material may be sandwiched between color filter layer  32  and thin-film transistor layer  34 . Layer  32  may contain an array of color filter elements for providing display  14  with the ability to display color images for viewer  56 . Layer  34  may contain an array of display pixels electrodes. The display pixel electrodes may be used to impose electric fields on portions of the liquid crystal layer, thereby creating an image on display  14 . Thin-film transistor circuitry on layer  34  may be used to route control signals from a display driver circuit (e.g., a display driver integrated circuit) to display pixel thin-film transistors and electrodes on layer  34 . Layers  32  and  34  may be sandwiched between upper polarizer layer  30  and lower polarizer layer  36 . 
     One or more chassis structures such as chassis structures  58  may be used in forming display  14 . Chassis structures  58  may include a plastic chassis structure (sometimes referred to as a p-chassis) and/or a metal chassis structure (sometimes referred to as an m-chassis). These chassis structures may be used in supporting the structures of display  14  such as backlight structures  20  and display layers  38  (as an example). Structures such as structure  38  may be mounted on a planar internal housing structure such as internal housing structure  60  (sometimes referred to as a mid-plate member or sheet metal structures). Sealing structures  44  may be used in forming a seal between structures such as cover glass  50 , touch sensor layer  40 , display layers  38  (e.g., upper polarizer  30 , color filter layer  32 , thin-film transistor layer  34 , and/or lower polarizer layer  36 ), backlight structures  20 , chassis structures  58 , internal housing structures such as structures  60 , housing  12 , and/or other structures in device  10 . 
     Device  10  may include internal components such as components  62 . Components  62  may include integrated circuits, connectors, switches, resistors, capacitors, and inductors, and other circuit components. Components  62  may be mounted on one or more support structures such as substrate  64 . Substrates such as substrate  64  may be formed from a rigid printed circuit board material (e.g., fiberglass-filled epoxy material such as FR4) or a flexible printed circuit substrate material such as polyimide or a sheet of other flexible polymer. Substrate  64  may be mounted within housing  12 . 
     As shown in the cross-sectional diagram of  FIG. 3 , sealing structure  44  in device  10  may be formed from a tape-based structure having a C-shaped cross-sectional shape. Sealing structure  44  may be used to seal air gap  42  against dust (i.e., to form a dust barrier between cavity  46  and air gap  42 ). Structure  44  may have an elongated strip shape that extends along the edges of display  14  (i.e., into the page in the orientation of  FIG. 3 ). In a rectangular display, there may be, for example, four strips of C-shaped tape  44 , forming dust seals for each of the four air gaps around the periphery of rectangular air gap region  42 . 
     Tape-based sealing structure  44  may be formed from a strip of fabric, a strip of plastic, a strip of flexible metal foil, strips of other materials, or combinations of these structures. Adhesive may be embedded within the tape of sealing structure  44  (e.g., within the fibers of a fabric tape) or separate layers of adhesive may be used in attaching tape sealing structure  44  to the structures of device  10  (e.g., layers of adhesive on one or both sides of a plastic or metal tape substrate). 
     In the example of  FIG. 3 , tape-based sealing structure  44  has been used to form a seal between inner surface  66  of display cover layer  50  and exposed surface  68  of color filter layer  30 . This is merely illustrative. C-shaped tape sealing structure  44  of  FIG. 3  may be attached between any two or more structures in device  10 , if desired. As an example, the upper portion of tape  44  may be attached to inner surface  70  of touch sensor  40 , whereas the lower portion of tape  44  may be attached to uppermost surface  72  of thin-film transistor layer  34 . Tape  44  may be bowed outwards (as shown in the example of  FIG. 3 ) or may be bowed inwards. 
     In the illustrative configuration of  FIG. 4 , tape-based sealing structure  44  has an S-shaped cross section. Tape-based sealing structure  44  may have one end that is attached to display cover layer  50  and housing  12  and an opposing end that is attached to surface  68  of color filter layer  32 . 
     As shown in the cross-sectional end view of sealing structure  44  of  FIG. 5 , sealing structure  44  may be based on a compressible structure having an inner biasing structure such as biasing structure  74  and an outer environmental sealing layer such as layer  76 . Sealing structure  44  may have an elongated shape (e.g., an elongated tube shape) that has a longitudinal axis that extends into the page (in the orientation of  FIG. 5 ). Biasing structure  74  may be optimized for providing a weak outwards biasing force, so the amount of restoring force that is generated when sealing structure  44  is compressed between opposing device structures such as structures  78  and  80  is relatively small. Biasing structure  74  may be formed, as an example, from foam (e.g., a weak foam that potentially has relatively large voids), from plastic or metal fibers, or other structures that weakly press outwardly when compressed. Structures  78  and  80  may include a display cover layer, a touch sensor layer, display layers such as polarizer layers, color filter layers, thin-film transistor layers, backlight structures, housing structures such as housing walls and internal planar mid-plate structures, other structures in device  10  and combinations of these structures. 
     Because the materials that form biasing structure  74  are configured to provide only a relatively small amount of outwards force when compressed, the addition of one or more dust barrier layers such as layer  76  may be used to help enhance the dust sealing capabilities of sealing structure  44 . Layer  76  may be formed from plastic (e.g., a sheet of a thin flexible polymer that has been wrapped fully or partly around the core structure formed from biasing structure  74 ), fabric, flexible metal foil, portions of foam  74  that have been locally melted and resolidified using heat and/or chemicals, or other structures that serve as dust barriers. In the example of  FIG. 5 , there is a single dust barrier layer surrounding biasing structure  74 . If desired, two or more layers such as layer  76  may be wrapped around biasing structure  74 . The configuration of  FIG. 5  is merely illustrative. 
     With an arrangement of the type shown in  FIG. 5 , layer  76  has an O-shaped cross-sectional shape that completely surrounds the periphery of biasing structure  74 .  FIG. 6  is a cross-sectional view of an illustrative dust sealing structure in a configuration in which dust barrier layer  76  extends only partly around the biasing structure. As shown in  FIG. 6 , dust sealing layer  76  may have a C-shaped cross-sectional shape that covers both the upper and lower surface of biasing structure  74 . Other cross-sectional shapes may be used for dust sealing layers such as layer  76 , if desired. 
     As shown in  FIG. 7 , dust sealing structure  44  may be formed from a compressible structure formed from an elastomeric material such as silicone or other elastomeric polymers (i.e., a solid non-foam polymer structure having a Shore A hardness of 15 to 70, less than 70, less than 50, less than 30, less than 20, more than 15, etc.). During assembly operations, layers such a display cover layer  50  and touch sensor layer  40  may be moved in direction  86  while display layers  38  such as upper polarizer layer  30 , color filter layer  32 , thin-film transistor layer  34 , and lower polarizer  36  are moved in direction  88 . When device structures are moved towards each other in this way, dust sealing structures  44  may be compressed between a layer such as touch sensor layer  40  and a layer such as color filter layer  32  (as an example). Portion  82  of dust sealing structure  44  may press upwards in direction  88  against touch sensor layer  40 , whereas portion  84  of dust sealing structure  44  may press downwards in direction  86  against color filter layer  32 , thereby sealing off air gap  42  of display  14  from dust and other contaminants in the external environment. 
     When compressed towards each other, portions  82  and  84  may move towards each other slightly, thereby narrowing the air gap formed by dust sealing air cavity  85 . As shown in  FIG. 7 , air cavity  85  may be partly surrounded by the upper and lower portions of dust sealing structure  44  (i.e., the protruding portions of structure  44  that are formed from the solid elastomeric material may partly enclose air cavity  85 ). 
     The cross-sectional shape of dust sealing structure  44  of  FIG. 7  has an open P-shape (C-shape). Another cross-sectional shape that may be used by an elastomeric member for dust sealing structure  44  is shown in  FIG. 8 . As shown in the example of  FIG. 8 , dust sealing structure may have an upper portion such as portion  90  that bears against touch sensor layer  40  and may have lower portions such as lower portion  92  that bears against polarizer  30  and lower portion  94  that bears against a different layer in display layers  38  such as color filter layer  32 . As with the example of  FIG. 7 , the material that forms dust sealing structure  44  of  FIG. 8  may be a solid (non-foam) elastomeric polymer such as silicone and may be configured to partly surround air cavity  85 . 
     In the illustrative configuration of  FIG. 9 , elastomeric dust sealing structure  44  has been formed from portions of solid (non-foam) elastomeric material having a C-shaped (U-shaped) cross section with opposing upper portions such as portions  96  and  98  that bear against touch sensor layer  40  (as an example) and a lower portion such as portion  100  that bears against a display layer such as color filter layer  32  of display structures  38 . As shown in  FIG. 9 , dust sealing structure  44  may partly surround air cavity  85 . When display cover layer  50  and touch sensor layer  40  are pressed inwardly against display layers  38 , sealing structure  44  may be compressed, thereby forming a dust seal for air gap  42 . A wiping motion may be created in which protrusion  96  of structure  44  moves along the lower surface of touch sensor layer  40  in direction  102  while protrusion  98  of structure  44  moves along the lower surface of touch sensor layer  40  in opposing direction  104 . Wiping motions such as these may help create a satisfactory dust seal without imposing excessive restoring force that might press apart structures such as touch sensor layer  40  and display layers  38 . Protrusions such as protrusion  82  of dust sealing structure  44  of  FIG. 7  and protrusion  90  of dust sealing structure  44  may also exhibit a wiping motion when the structures between which they are located are moved towards each other. 
     Elastomeric members such as the illustrative dust sealing structures  44  of  FIGS. 7 ,  8 , and  9  and other dust sealing structures  44  may have rectangular shapes when viewed in direction  106  of  FIG. 2 . A top view of an illustrative configuration that may be used for dust sealing structure  44  is shown in  FIG. 10 . As shown in  FIG. 10 , dust sealing structure  44  may have a main rectangular portion such as portion  108  having four edges. Each edge in portion  108  may have a cross-sectional shape such as one of the shapes of  FIG. 7 ,  8 , or  9  or other cross-sectional dust sealing structure shapes. If desired, integral positioning structures such as protrusions  110  may be formed on structure  108 . Positioning structures  110  in the example of  FIG. 10  have the shape of protrusions with openings such as openings  112 . During assembly, an assembly tool (e.g., a fixture with a position that is adjusted by a computer-controlled positioner) may insert pins into openings  112  to control the position of dust sealing structure  44  relative to other structures in device  10 . 
     If desired, a cutting tool, laser-based cutter, or other assembly equipment may be used in trimming off protrusions  110  following use of protrusions  110  in aligning dust sealing structure  44  relative to structures in device  10  such as display layers  38 , touch sensor layer  40 , and other structures. 
     As shown in  FIG. 12 , an elastomeric sealing structure or other sealing structure that forms a bowed-out shape of the type shown in  FIG. 12  may satisfactorily accommodate changes in air pressure on either side of the seal (e.g., when a display or device is flexed during use). Air pushing in direction  120  from the left side of dust sealing gasket  44  of  FIG. 12  may press portion  114  of sealing structure  44  sufficiently to cause portion  114  to expand from position  116  outwards in directions  118 . When the air pressure in direction  120  subsides, portion  114  of dust sealing structure  44  can return to position  116 . Allowing dust sealing structure  44  to expand and contract in this way (with or without an accompanying wiping motion along the surfaces of structures  78  and/or  80 ) may help avoid damage to device  10  and/or dust sealing structures  44  during events that give rise to changes in internal air pressure adjacent to dust sealing structure  44 . 
     An elastomeric dust sealing structure such as structure  44  may be formed by polymer molding operations. As shown in  FIG. 13 , for example, a tool such as plastic molding tool  122  may have a number of portions such as portions  124 ,  126 , and  128  that mate to form a cavity having a desired shape for structure  44 . Injection molding operations or other plastic molding operations may be used in forming dust sealing structure  44  using equipment  122 . 
       FIG. 14  shows how dust sealing structures  44  may be temporarily mounted on a support structure such as release liner  132  using adhesive  130 . When it is desired to mount dust sealing structure  44  in device  10 , dust sealing structure  44  may be peeled away from release liner  132  (manually or using an assembly tool). 
     If desired, dust sealing structure  44  may be formed from a compressible material such as a compression-set foam. The foam may initially have a thickness T 1 , as shown in  FIG. 15 . Following compression of the foam between structures  78  and  80  to reduce the thickness of dust sealing structures  44  to thickness T 2  (i.e., a thickness that is less than thickness T 1 ), processing operations may be performed by assembly tools  134  to set the foam in its compressed state. As an example, the compressed foam may be subjected to heat (thermal energy) and/or ultrasonic signals (acoustic energy) in the presence of a humid ambient environment (e.g., an environment with water vapor and/or chemicals to encourage the foam to set and remain at or near its compressed thickness). By processing the compressed foam in this way, the foam may be maintained at its compressed thickness T 2  and the restoring force that is exhibited by the compressed foam may be reduced significantly. 
     Illustrative steps involved in forming an electronic device having a dust sealing member formed from a material such as a compression-set foam are shown in  FIG. 16 . 
     At step  136 , a compressible polymer foam material that is configured to accept a set when processed may be installed in a portion of device  10 . For example, a compression-set foam member having the shape of a rectangular ring or other suitable shape may be installed along the four peripheral edges of a rectangular display (e.g., display layers  38 ). The foam member may, as an example, be placed on top of a layer such as color filter layer  32  or thin-film-transistor layer  34 . An optional layer of adhesive (e.g., pressure sensitive adhesive) may be used in attaching the foam member to display layers  38 . 
     At step  138 , additional components of device  10  may be assembled. As an example, display layers  38  may be mounted in housing  12  and additional layers such as display cover layer  50  and touch sensor layer  40  may be mounted within housing  12 . When mounting display cover layer  50  and touch sensor layer  40  within device  10 , the undersides of one or both of these layers may press against the upper surface of the compressible foam member. For example, the lower surface of touch sensor layer  40  and/or the inner surface of display cover layer  50  may press against the compressible foam member. As described in connection with  FIG. 15 , this may compress the foam member until its thickness is reduced from initial thickness T 1  to reduced thickness T 2 , thereby ensuring a satisfactory dust seal for device  10 . A dust seal that is formed in this way may be used to seal air gap  42  against dust from other portions of device  10  such as cavity  46  ( FIG. 2 ). If desired, an optional layer of adhesive such as a layer of pressure sensitive adhesive may be used to help secure the foam member to the touch sensor layer and/or the display cover layer. 
     At step  140 , the assembled device structures may be processed using assembly equipment  134  of  FIG. 15 . Assembly equipment  134  may include equipment for applying pressure (e.g., computer-controlled positioners for compressing structures in device  10  together to compress the foam), equipment for applying energy in the form of heat (e.g., an oven, heat lamp, laser, hot bar, or other heat source), equipment for applying energy in the form of acoustic signals such as an ultrasonic signal generator that applies ultrasonic acoustic signals, equipment for exposing the device structures to an atmosphere that contains an elevated amount of water vapor (e.g., as part of a humid air environment) or other liquid or gaseous chemicals, and other tools for processing and treating the structures of device  10  and the compressed foam. Applying heat in the range of 50° C. to 80° C. may be helpful in setting the foam in its compressed state. Restricting applied heat levels to less than about 60° C. may be helpful in scenarios in which device  10  includes sensitive components such as magnets that might demagnetize with prolonged exposure to temperatures above 60° C. (as an example). 
     When processed during the operations of step  140 , the energy and/or chemicals that are applied to the compressed foam cause the compressed foam to become fixed in its compressed state, thereby relieving the structures of device  10  from the restoring force that would otherwise be generated by the compressed foam attempting to regain its original uncompressed shape. Setting the compressed foam in its compressed state may therefore cause the compressed foam to form a low-force dust seal for device  10 . 
     If desired, a low-force dust seal may be formed by applying the dust seal material to the structures of device  10  in liquid form followed by curing operations to solidify the liquid material. For satisfactory processing, it may be desirable to use a relatively cohesive material such as a two-part silicon adhesive with a 5-30 minute cure time in forming the low-force dust seal. This material (e.g., material  44 M of  FIG. 17 ) may be placed between opposing device structures such as structures  78  and  80  of  FIG. 17 . Structures  78  and  80  of  FIG. 17  may include a display cover layer, a touch sensor layer, display layers such as polarizer layers, color filter layers, thin-film transistor layers, backlight structures, housing structures such as housing walls and internal planar mid-plate structures, other structures in device  10  and combinations of these structures. By using a cohesive material, undesirable wicking effects which might result in damage to expensive display structures can be avoided. Cohesive materials such as material  44 M may also make it possible to rework or repair device  10 . 
     As shown in  FIG. 17 , when a sufficiently cohesive material is used such as material  44 M, material  44 M will tend to stick to itself and either structure  78  or  80  when structures  78  and  80  are pulled apart. For example, in some situations, separation of structures  78  and  80  will result in material  44 M becoming stuck to structure  78 , as shown by arrow  142 , whereas in other situations, separation of structures  78  and  80  will result in material  44 M becoming stuck to structures  80 . 
     In addition to being formed from a highly cohesive material, it may be desirable for material  44 M to be sufficiently viscous to form a shape of the type shown in  FIG. 18  in which material  44 M maintains a height that is equal to or greater than its width when placed on a support structure (i.e., support  146  of  FIG. 18 ). When formed from a material that sustains an aspect ratio of greater than or equal to 1:1 (width X and height X being equal), a dust seal structure may be assembled without wicking or leaking into undesired portions of device  10 . In an illustrative configuration, the value of X may be about 1 mm for sealing an air gap such as air gap  42  with a size of about 0.3 to 0.7 mm. 
     Material  44 M may also be formed from a low durometer material (i.e., a material that is sufficiently soft that it does not impose strain on display layers  38  and other components of display  14  that would lead to light leakage). An example of a soft material that may be used for material  44 M is a material that has Shore A hardness of 15 to 70 (or less than 70, less than 50, less than 30, less than 20, more than 15, etc.). 
     Using a two-part mixture for material  44 M or other suitable formulation, material  44 M may be configured to cure at a relatively low temperature (e.g., room temperature or a slightly elevated temperature). Material  44 M preferably exhibits low outgassing (e.g., sufficiently low outgassing to avoid creating obstructions that lead to visible artifacts during the operation of display  14 ). If desired, absorbing structures may be incorporated into display  14  to reduce or eliminate fogging from outgassing material  44 M. 
     Equipment of the type that may be used to dispense material  44 M in liquid form is shown in  FIG. 19 . As shown in  FIG. 19 , liquid dust sealant dispensing equipment  148  may include a computer-controlled positioner such as computer-controlled positioner  150  and a liquid sealant dispensing nozzle such as nozzle  152 . During operation, computer-controlled positioner  150  may be used to run nozzle  152  along the edges of display  14 , thereby dispensing liquid material  44 M between display layers such as touch sensor layer  40  and color filter layer  32  or other layers (e.g., cover layer  50 , layers among display structures  38 , housing structures, etc.). A spacer structure such as spacer  162  of  FIG. 19  may be used to ensure that the thickness of air gap  42  (i.e., the separation between touch sensor layer  40  and display layers  38 ) is accurately maintained at a desired value during curing operations. Following curing, material  44 M may form low-force dust sealing structure  44  of  FIG. 19 . 
     Illustrative steps involved in forming low-force dust sealing structures using liquid materials such as material  44 M are shown in  FIG. 20 . 
     At step  154 , display components such as backlight structures  20  and display layers  38  may be installed within housing  12  of device  10  (e.g., by mounting these structures on an internal support structures such as internal housing structure  60  of  FIG. 2 ). 
     At step  156 , a liquid bead of material  44 M may be dispensed to form a liquid ring of material that runs around the rectangular periphery of display layers  38  in display  14 . As an example, equipment  148  of  FIG. 19  may be used to dispense a bead of material along the edge of display layers (e.g., a bead of material that runs along the rectangular periphery of color filter layer  32  or other suitable display layers). If desired, the liquid bead of material may be dispensed on display layers  38  prior to assembly of layers  38  into housing  12 . 
     At step  158 , additional device structures may be attached to the display layers. As an example, display cover layer  50  and touch sensor layer  40  may be lowered on top of display layers  38 , thereby compressing liquid material  44 M between opposing structures such as touch sensor layer  40  and color filter layer  32 . Because material  44 M is liquid, no significant restoring force will generally be created by material  44 M following compression. 
     At step  160 , assembly tools such as assembly tools  134  of  FIG. 15  may be used in curing material  44 M to form dust sealing structure  44 . In curing material  44 M, heat may be applied (e.g., heat that elevates the temperature of material  44 M above room temperature) or material  44 M may be cured by waiting for a specified amount of time at room temperature. The environment to which material  44 M is exposed may, if desired, be adjusted to promote curing. As an example, material  44 M may be exposed to an atmosphere with a humidity that is elevated with respect to the ambient atmosphere, an environment that contains liquid and/or gaseous chemicals that promote curing, etc. 
     Once material  44 M has cured, dust sealing structure  44  may be used to prevent dust and other environmental contaminants from entering sensitive portions of device  10  such as air gap  42  within display  14 . Because liquid material  44 M was used in forming sealing structure  44 , the structures that form sealing structure  44  will not generally resist compression during the assembly operations of step  158 . As a result, following curing operations at step  160 , dust sealing structure  44  will not produce forces that tend to disassemble the sealed structures in device  10 . 
       FIG. 21  shows how dust sealing structure  44  may be formed as part of a display assembly such as display assembly  164 . Dust sealing structure  44  may be formed using a tape-based sealing structure, using an elastomeric sealing structure, using a compression-set foam structure, or using a cured liquid structure (as examples). Assembly  164  may be formed by assembling the components of assembly  164  such as display cover layer, touch sensor layer  40 , display layers  38 , and dust sealing structure  44  prior to mounting assembly  164  in device housing  12  in direction  166 . 
     As shown in  FIG. 22 , dust sealing structures such as dust sealing structure  44  may be formed by injecting potting compound  44 P into device  10 . Potting compound  44 P may be formed from a curable liquid such as liquid material  44 M or other suitable material that can be cured (e.g., at room temperature, using an elevated temperature, under ultraviolet light exposure, etc.). Potting compound  44 P may be injected into device  10  using equipment such as equipment  148  of  FIG. 19 . Assembly tools such as tools  134  of  FIG. 15  may be used in curing potting compound  44 P following injection into device  10 . A spacer such as spacer  162  may be used to help regulate the separation between touch sensor layer  40  and display layers  38  (i.e., the size of air gap  42 ). Following curing, material  44 P may form a solid dust sealing structure such as dust sealing structure  44 . In the example of  FIG. 22 , dust sealing structure  44  has been formed between opposing structures such as display cover layer  50  (and touch sensor layer  40 ), display layers  38 , and housing  12 . This is merely illustrative. Seals such as dust seal  44  of  FIG. 22  may be formed between any two or more structures in device  10 . 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20120620
Publication Date: 20151229
Grant Date: 20151229
Priority Date: 20120620
Inventors: FRANKLIN JEREMY C.
AI JIANG
QIAN AMY
RAPPOPORT BENJAMIN M.
GIBBS KEVIN D.
WRIGHT DEREK
TERNUS JOHN P.
RAFF JOHN
MCCLURE STEPHEN R.
Assignee: APPLE INC
CPC Classifications: [{"code": "Y10T29/49863", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1658", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1656", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1643", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49865", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49865", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1643", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1656", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49863", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1658", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 49774255