PATENT DOCUMENT

Publication Number: US-9060418-B2
Application Number: US-201213607530-A
Country: US
Kind Code: B2

Title: Systems and methods for improved window mounting on an electronic device

Abstract:
Systems and methods for improved window mounting on electronic devices are provided. A window mounting assembly can include a heat activated adhesive, such as a heat activated film (“HAF”), which can be used to secure a window to an enclosure. In some embodiments, heated air can be blown in from a bottom side of the window, which can provide better offset control in the assembly. In some embodiments, an undercut can be made in the enclosure that can act as a trap for HAF overflow. An overhang that is created by the undercut can reduce the visibility of HAF overflow from a user. In addition, the heated air that is applied to the window can create a high pressure region in an area underneath the window. The high pressure region can direct the HAF overflow away from this area and towards the undercut in the enclosure.

Claims:
What is claimed is: 
     
       1. A method for using a heat activated adhesive for mounting a window on an electronic device, the window comprising first, second, and third sides, the method comprising:
 applying the first side of the window to an enclosure, wherein the enclosure surrounds the window on at least a portion of the first side and the second side, and at least the portion of the first side comprises the heat activated adhesive; 
 applying the third side of the window to an unmoving assembly fixture datum; and 
 applying heated air to the first side of the window such that the third side of the window is biased against the unmoving assembly fixture datum, wherein the application of the heated air cures the heat activated adhesive and secures the first side of the window to the enclosure. 
 
     
     
       2. The method of  claim 1 , wherein the heat activated adhesive is a heat activated film (“HAF”). 
     
     
       3. The method of  claim 1 , further comprising pressing a side of the enclosure against the unmoving assembly fixture datum. 
     
     
       4. The method of  claim 3 , wherein the side of the enclosure is pressed against the unmoving assembly datum surface until both the third side of the window and the side of the enclosure are touching the unmoving assembly fixture datum. 
     
     
       5. The method of  claim 3 , wherein pressing the side of the enclosure comprises using a fixture to press the side of the enclosure against the unmoving assembly fixture datum. 
     
     
       6. The method of  claim 5 , wherein the fixture is a ring. 
     
     
       7. The method of  claim 5 , wherein the fixture is spring-loaded. 
     
     
       8. The method of  claim 1 , wherein the heated air creates a high pressure region underneath the window. 
     
     
       9. The method of  claim 8 , wherein pressure of the high pressure region directs overflow of the heated activated adhesive away from the high pressure region. 
     
     
       10. The method of  claim 1 , wherein the heat activated adhesive is a thermoset. 
     
     
       11. The method of  claim 1 , wherein the heat activated adhesive cures into a solid material. 
     
     
       12. The method of  claim 1 , wherein the heat activated adhesive cures into plastic. 
     
     
       13. A method for using a heat activated adhesive for mounting a window on an electronic device, the window comprising first and second opposing sides connected by a third and fourth opposing sides, the method comprising:
 placing the first side of the window on an enclosure, wherein the enclosure partially surrounds the window, and wherein the heat activated adhesive is formed on the first side of the window; 
 placing an unmoving assembly fixture on the second side of the window; and 
 applying heated air to the first side of the window to bias the second side of the window against the unmoving assembly fixture, wherein the application of the heated air cures the heat activated adhesive and secures the first side of the window to the enclosure. 
 
     
     
       14. The method of  claim 13 , wherein the enclosure surrounds only a portion of the first side of the window, the entire third side of the window, and the entire fourth side of the window. 
     
     
       15. The method of  claim 13 , wherein the first side of the window has a periphery, and wherein the heat activated adhesive is formed on the periphery of the first side of the window. 
     
     
       16. The method of  claim 13 , wherein placing the unmoving assembly fixture on the second side of the window comprises the entire second side of the window being placed in direct contact with the unmoving assembly fixture. 
     
     
       17. The method of  claim 13 , further comprising monitoring the temperature of the heated air with one or more temperature sensors. 
     
     
       18. The method of  claim 1 , wherein the second side of the window has first portion that is directly adjacent to a side of the enclosure. 
     
     
       19. The method of  claim 18 , wherein the second side of the window has a second portion that is not directly adjacent to the side of the enclosure. 
     
     
       20. The method of  claim 19 , wherein overflow of the heat activated adhesive flows into a recess formed in between the second portion of the second side of the window and the side of the enclosure.

Description:
FIELD OF THE INVENTION 
     This can relate to systems and methods for improved window mounting on an electronic device. 
     BACKGROUND OF THE DISCLOSURE 
     Many electronic devices (e.g., media players and cellular telephones) often include one or more transparent windows as protective covers for functional components. For example, an electronic device can have a camera lens and/or a display that needs to be protected by transparent windows. An adhesive, typically a liquid adhesive or a pressure sensitive adhesive (“PSA”), may be used to mount a window to the electronic device. 
     These conventional adhesives, however, can present multiple challenges during the mounting process. In particular, the thicknesses of PSAs are not precisely controllable. Liquid adhesives require both a significant time to cure and large amounts of assembly equipment and space during mass production. Furthermore, both PSAs and liquid adhesives have overflow issues during mounting. 
     SUMMARY OF THE DISCLOSURE 
     Systems and methods are disclosed for improved window mounting on electronic devices. A window mounting assembly can include a heat activated adhesive, such as a heat activated film (“HAF”), which can be used to secure a window to an enclosure of an electronic device. 
     In some embodiments, heated air can be blown in from a bottom side of the window. This can provide better offset control in the assembly, which can allow the window to be set to a precise height relative to the enclosure. As used herein, an “offset” can refer to the normal distance between a window and the surrounding enclosure. As a result of the application of heated air, a zero offset between the window and the surrounding enclosure can be achieved. This can improve both the cosmetics and overall reliability of the assembly. 
     In some embodiments, an undercut can be made in an enclosure that can act as a trap for HAF overflow. An overhang that is created by the undercut can reduce the visibility of the HAF overflow from a user. 
     In addition, the heated air that is applied to the bottom side of the window can create a high pressure region in an area underneath the window. This area can be open to one or more functional components, which may need to be protected from HAF overflow. The high pressure region can direct the HAF overflow away from this area and towards the undercut in the enclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects of the invention, its nature, and various features will become more apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
         FIG. 1  is a cross-sectional view of a conventional window mounting of an electronic device assembly; 
         FIG. 2  is a cross-sectional view of a system with another window mounting assembly; 
         FIGS. 3A-3C  are perspective views of a window mounting assembly of an electronic device in accordance with some embodiments of the invention; 
         FIG. 4  is a cross-sectional view of a system for creating the window mounting assembly of  FIGS. 3A-3C  in accordance with some embodiments of the invention; and 
         FIG. 5  is a flowchart of an illustrative process for creating a window mounting assembly in accordance with some embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Systems and methods for window mounting assemblies on electronic devices are provided and described with reference to  FIGS. 1-5 . 
       FIG. 1  is a cross-sectional view of a conventional window mounting assembly  100  of an electronic device. The electronic device can be any suitable electronic device having one or more windows. The term “electronic device” can include, but is not limited to, music players, video players, still image players, game players, other media players, music recorders, video recorders, cameras, other media recorders, radios, medical equipment, domestic appliances, transportation vehicle instruments, musical instruments, calculators, cellular telephones, other wireless communication devices, personal digital assistants, remote controls, pagers, computers (e.g., desktops, laptops, tablets, servers, etc.), monitors, televisions, stereo equipment, set up boxes, set-top boxes, boom boxes, modems, routers, keyboards, mice, speakers, printers, and combinations thereof. In some embodiments, the electronic device may perform a single function (e.g., a device dedicated to playing music) and, in other embodiments, the electronic device may perform multiple functions (e.g., a device that plays music, displays video, stores pictures, and receives and transmits telephone calls). 
     The one or more windows can serve as protective covers for one or more functional components such as, for example, displays or cameras. Persons skilled in the art will appreciate that the windows can be used as protective covers for any suitable functional component of an electronic device (e.g., any component that requires an optical view to the exterior of the electronic device). Thus, the windows can be any suitable size and can be made of any suitable material (e.g., a transparent material such as polished glass, plastic, and/or polished ceramic). In some cases, for example, the window can be a lens. In some embodiments, the windows can have a cosmetic mask (e.g., ink) on one or more portions. 
     Various characteristics of the window can pose challenges for the mounting process. For example, the window can be made of glass that do not have any features that are suitable for mounting. As a result, the window can only be mounted on a device using an adhesive. In addition, because the window made be made of glass and/or ceramic, the window may be sensitive to impact. In addition, if the window is transparent, any overflow from an adhesive may be easily visible. 
     In order to ensure that a window is mounted properly on the device, the offset and the bond strength of the window mounting assembly can be particularly important. As used herein, the “offset” can refer to the normal distance between a window and the surrounding enclosure. Furthermore, as used herein, the “bond strength” can refer to the minimum force required to push or pull the window off the enclosure. 
     In particular, a zero or negative offset (e.g., where the window is lower than the surrounding enclosure) can provide a more robust design. That is, if the window is made of a fragile material, a flush or sub-flush design can reduce the likelihood that the window will be the initial strike surface in a drop. Rather, another portion of the housing of the electronic device, which may be made from a more robust material such as metal or plastic, can take the initial impact. 
     In addition, in terms of cosmetics, zero offsets can provide a more uniform and precise surface. Moreover, zero offsets may allow the electronic device to have fewer steps and gaps. These steps and gaps are undesirable because they may catch on fabrics, edges, etc., and can collect dust, dirt, or grime. Thus, being able to control the height of an adhesive (e.g., ensuring evenness of the adhesive during application) is important for producing a zero offset in a window mount. 
     In addition, a maximized bond strength can improve the reliability of the electronic device during drop testing and rough handling. Thus, adhesive strength is also important when considering various mounting alternatives. 
     For example, as shown in  FIG. 1 , adhesive  102  can be used to mount window  104  to enclosure  106  of the electronic device. Adhesive  102  can be a pressure sensitive adhesive (“PSA”) or a liquid adhesive (e.g., liquid glue). Enclosure  106  (e.g., housing) can be a cosmetic trim, and can be made of any suitable material such as, for example, plastic (e.g., molded plastic) and/or metal. Window  104  can serve as a protective cover for functional component  108 , which can be a display and/or a camera. In some cases, window  104  can have cosmetic mask  110 , which can be printed or silk screened ink. Offset  112  can vary depending on the thickness of window  104 , the thickness of adhesive  102 , and/or the size tolerances of enclosure  106 . 
     Die-cut PSAs can have a soft or spongy texture, and thus may spring back once assembled. As a result, window  104  may move relative to other components over time. In addition, the thicknesses of PSAs are not precisely controllable. Hence, offset  112  between window  104  and enclosure  106  may vary for different assemblies. Offset  112  may also vary based on temperature fluctuations. Furthermore, PSAs contain a tacky surface, which can collect foreign materials if the PSA is misaligned. PSAs also have relatively weak bonding strengths as compared to other adhesives. 
     Liquid adhesives, on the other hand, can be used along with assembly fixtures to set precise offsets. However, these adhesives require significant time to cure and large amounts of assembly equipment and space during mass production. 
     For both PSAs and liquid adhesives, there can be overflow (e.g., squeeze out). For example, liquid adhesive dispensation volumes can vary during manufacturing, which can lead to undesirable overflow in cosmetic area  114  and functional area  116  for a certain percentage of assemblies. This can either result in production loss or necessitate re-work. 
     Thus, in some cases, heat activated film (“HAF”) adhesives can be used instead of PSAs or liquid adhesives. HAF is a thermoset, which can be a heat-activated resin (e.g., phenolic resin) in its initial form. Following a curing (e.g., activation) process, during which heat and pressure are jointly applied to the heat-activated resin, the HAF can be set to its final adhesive form (e.g., a solid material such as plastic). After the HAF has been cured, the HAF can be die-cut. 
     HAFs can offer higher bonding strengths (e.g., five to ten times higher) than PSAs. In addition, unlike PSAs, HAFs can cure to a solid state. Thus, HAFs can allow some control over final offset. Moreover, unlike liquid adhesives, HAFs do not need complex dispensation equipment during the mounting process because HAFs are solid. 
     For example, referring now to  FIG. 2 , a cross-sectional view of system  200  is shown with window mounting assembly  201 . In particular, HAF  202  can be used to mount window  204  to enclosure  206 . Window  204  and enclosure  206  can be the same as or similar to window  104  ( FIG. 1 ) and enclosure  106  ( FIG. 1 ), respectively. In some cases, enclosure  206  can be placed on assembly fixture datum  213 . 
     During assembly, heated block  208  (e.g., a heated head) can be applied to side  210  of window  204 . Heated block  208  can be pressed down for both a pre-determined period of time and a pre-determined distance. Heat from heated block  208  can conduct through window  204 , which can then heat up mask  212  and HAF  202 . 
     Unfortunately, heat conduction losses through the various components (e.g., window  204  and mask  212 ) may cause variations in the temperature of heat that actually reaches HAF  202  (e.g., varying degrees of temperature drops). As a result, experiments are needed in order to estimate the actual temperature of heat that reaches HAF  202 . This unpredictability can complicate the manufacturing process. 
     In addition, during the curing process, HAF  202  can ooze and flow in a manner that is similar to a liquid adhesive. Thus, HAF  202  can create similar cosmetic and functional challenges such as, for example, overflow in cosmetic area  214  and functional area  216 . 
     Furthermore, the reliability of assembly  201  can vary based on the various tolerances of components that are stacked up against heated block  208 . For example, if window  204  and HAF  202  are relatively thick in comparison to enclosure  206 , there may be a large amount of HAF squeeze out. In contrast, if window  204  and HAF  202  are relatively thin in comparison to enclosure  206 , there may not be enough of HAF squeeze out, which can lead to a weak mount. 
     As another example, if enclosure  206  is plastic or has a heat tolerance that is below the temperature of heat applied during the HAF curing process, enclosure  206  cannot be used as a touch-off surface for heated block  208 . As yet another example, offset  218  can vary as a result of press head location during assembly. In some cases, in order to create a controlled offset, the press head can be designed to bottom against enclosure  206  (e.g., press against side  220  of enclosure  206 ). This, however, may cause heat damage to the enclosure material. Moreover, there can still be variability in offset  218  depending on the tolerances of components of assembly  201 . 
     Accordingly, in order to obtain greater precision in window mounting applications that use HAFs, several improvements can be made over existing assemblies. In particular, instead of using a heated block to press into a window from a top side, heated air can be blown in from a bottom side of the window. This can provide better offset control in the assembly, which can allow the window to be set to a precise height relative to an enclosure. In addition, an undercut can be created in the enclosure that can act as a trap for HAF overflow. 
     Referring now to  FIGS. 3A-3C , perspective views of a window mounting assembly  300  of an electronic device are shown.  FIG. 3A  shows a perspective view of assembly  300 . Assembly  300  can include window  302 , cosmetic mask  304 , and enclosure  306 . 
     Enclosure  306  can include undercut  312 , which can be formed on enclosure  306  using any suitable technique(s). For example, if enclosure  306  is metal, undercut  312  can be cut into inner surface  314 . 
       FIG. 3B  shows an exploded perspective view of assembly  300 , which can include HAF  308  between window  302  and enclosure  306 . Window  302  can include bottom side  310 , top side  320 , and surrounding side  330 . In some embodiments, window  302  can include cosmetic mask  304  on side  310 . In some cases, cosmetic mask  304  can be printed or silk screened on side  310 . 
       FIG. 3C  shows an exploded cross-sectional view of assembly  300 . 
     Turning now to  FIG. 4 , a cross-sectional view of system  400  is shown for creating window mounting assembly  300  of  FIGS. 3A-3C . In addition to assembly  300 , system  400  can include assembly fixture datum  402  and additional fixture  404 . Because assembly  300  has a circular shape, fixture  404  can be a ring that is pressing up against side  403  of enclosure  306 . However, persons skilled in the art will appreciate that fixture  404  can have any suitable shape. 
     Enclosure  306  can include undercut  312  between sides  403  and  406 . Side  403  can be located in the interior of an electronic device, and side  406  can be located in the exterior of an electronic device. Side  406  of enclosure  306  and side  320  of window  302  can be arranged underneath fixture datum  402 . In addition, window  302  can be coupled to HAF  308  on side  310 . 
     HAF  308  can be cured by directly applying forced heated air  410 . For example, as shown in  FIG. 4 , heated air  410  can be supplied to both side  310  of window  302  and HAF  308  by air heater  412 . Once HAF  308  reaches a final solid state via the curing process, window  302  can be secured to enclosure  306 . 
     In some cases, system  400  can include one or more temperature sensors (e.g., temperature sensors  414  and  416 ) configured to monitor the temperature of heated air  410 . The one or more temperature sensors can be thermocouples, which can be arranged below side  310  of window  302 . As shown, temperature sensors  414  and  416  can be standalone components. Persons skilled in the art will appreciate that the temperature sensors can be located in any suitable location in system  400  (e.g., attached to air heater  412 ). 
     In some embodiments, air heater  412  can adjust the temperature of heated air  410  based on one or more outputs of the temperature sensors. For example, air heater  412  can increase or decrease the temperature of heated air  410  until it reaches an optimal temperature for curing HAF  308 . 
     Because heated air  410  only needs to travel in a small functional area  420 , there may be very little temperature drop between when heated air  410  leaves air heater  412  and when it reaches HAF  308 . In addition, because heated air  410  is supplied directly to HAF  308 , the temperature of heated air  410  can be controlled more precisely than the temperature of heat applied to HAF  202  in system  200  ( FIG. 2 ). This can lead to better process control during assembly. 
     While heated air  410  is supplied to HAF  308 , fixture  404  can be used to bias (e.g., press) side  320  of window  302  and side  406  of enclosure  306  directly against fixture datum  402 . In particular, fixture  404 , which can be non-heated, can apply pressure to assembly  300  until side  320  of window  302  and side  406  of enclosure  306  are both touching the bottom surface of fixture datum  402 . In some cases, fixture  404  can be spring loaded. 
     Because assembly  300  can be biased directly against a flat, unmoving surface of fixture datum  402 , offset  422  can be more precisely controlled than offset  218  of system  200  ( FIG. 2 ). In particular, offset  422  can be controlled by a single flat surface (e.g., the flat bottom surface of fixture datum  402 ) rather than being dependent on the motion tolerances of heated block  208 . 
     Because offset  422  can be manufactured to be zero (e.g., side  406  of enclosure  306  can be co-planar with side  320  of window  302 ), there can be better reliability during drop tests. In addition, a zero offset can eliminate any gaps and steps that can catch on various objects. Cosmetics can also be improved because the outer surface of assembly  300  can appear as one clean uniform surface rather than several components that are pieced together. 
     While assembly  300  is being pressed against fixture datum  402  during the curing process, HAF  308  will need to flow and ooze out. Undercut  312  of enclosure  306  can form a trap for the HAF overflow in cosmetic area  423 . In addition, because overhang  424  is created in enclosure  306  by undercut  312 , overhang  424  can obscure the overflow from a user&#39;s line of sight. This reduced visibility of overflow can improve the overall cosmetics of assembly  300 . 
     The application of forced heated air  410  to side  310  of window  302  can also create a high pressure region in functional area  420  (e.g., an area directly underneath side  310  of window  302 ). Functional area  420  can be open to one or more functional components (e.g., camera and/or display) that are underneath window  302 . In some cases, the functional component(s) can be the same as or similar to functional component  108  of  FIG. 1 . 
     While HAF  308  cures to a solid state, the pressure of the high pressure region can direct the HAF overflow to cosmetic area  423  (e.g., flow into undercut  312 ) and away from functional area  420 . Thus, HAF overflow can be found only in a region (e.g., region  430 ) below cosmetic mask  304  of window  302  and in undercut  312 , and not in functional area  420 . As a result, functional components can be protected from HAF overflow. 
       FIG. 5  is a flowchart of an illustrative process  500  for creating a window mounting assembly (e.g., window mounting assembly  300  of  FIGS. 3A-3C  and  FIG. 4 ) in accordance with some embodiments of the invention. Process  500  may start at step  502 , and, at step  504 , a first side (e.g., side  310  of  FIG. 4 ) of a window (e.g., window  302  of  FIG. 4 ) can be applied to an enclosure (e.g., enclosure  306  of  FIG. 4 ), where the enclosure surrounds the window on at least a portion of the first side and a second side (e.g., side  330  of  FIG. 3B ), and at least the portion of the first side includes heat activated adhesive (e.g., heat activated adhesive  308  of  FIG. 4 ). In some cases, the heated activated adhesive can be a HAF. 
     At step  506 , a third side (e.g., side  320  of  FIG. 4 ) of the window can be applied to an unmoving assembly fixture datum (e.g., assembly fixture datum  402  of  FIG. 4 ). Continuing to step  508 , heated air (e.g., heated air  410  of  FIG. 4 ) can be applied to the first side of the window such that the third side of the window is biased against the unmoving assembly fixture datum, where the application of heated air cures the heat activated adhesive and secures the first side of the window to the enclosure. 
     In addition, a side (e.g., side  406  of  FIG. 4 ) of the enclosure can also be pressed against the unmoving assembly fixture datum. The biasing of the enclosure and the window can occur until both the third side of the window and the side of the enclosure are touching the assembly fixture datum. In some cases, a fixture (e.g., fixture  404  of  FIG. 4 ) can be used to press the side of the enclosure against the assembly fixture datum. Process  500  may then end at step  510 . 
     While there have been described assemblies for improved window mounting on an electronic device, it is to be understood that many changes may be made therein without departing from the spirit and scope of the invention. It is also to be understood that various directional and orientational terms such as “up” and “down,” “front” and “back,” “top” and “bottom” and “side,” “below” and “underneath,” and the like are used herein only for convenience, and that no fixed or absolute directional or orientational limitations are intended by the use of these words. For example, the devices of this invention can have any desired orientation. If reoriented, different directional or orientational terms may need to be used in their description, but that will not alter their fundamental nature as within the scope and spirit of this invention. 
     It is further to be understood that process  500  of  FIG. 5  is merely illustrative. Any of the steps may be removed, modified, or combined, and any additional steps may be added, without departing from the scope of the invention. 
     The described embodiments of the invention are presented for the purpose of illustration and not of limitation.

Metadata:
Filing Date: 20120907
Publication Date: 20150616
Grant Date: 20150616
Priority Date: 20120907
Inventors: SHUKLA ASHUTOSH Y.
LOUCHARD THOMAS R.
YAN VINCENT
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/1656", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/0017", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1656", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K5/0017", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1656", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 50233076