PATENT DOCUMENT

Publication Number: US-8958028-B2
Application Number: US-201113163570-A
Country: US
Kind Code: B2

Title: Protective film patterning

Abstract:
The patterning of objects (e.g., protective poly-films, heat-spreaders, and other components placed proximate to the backlight of an LCD) with multiple beads or raised protrusions is disclosed. The beads or protrusions can have a uniform or non-uniform size and can be arranged such that they have a uniform or non-uniform pattern density. The beads or protrusions can be patterned on a surface of the object to provide separation between a non-raised surface of the object and a surface of an adjacent item, such as a reflector film.

Claims:
What is claimed is: 
     
       1. A liquid crystal display comprising:
 a backlight assembly; 
 a reflector positioned against the backlight assembly; and 
 a protective film covering at least a portion of a surface of the reflector opposite the backlight assembly, wherein the protective film comprises a plurality of raised protrusions formed on a surface of the protective film contacting the reflector, wherein the raised protrusions comprise the same material as the protective film, and wherein the plurality of raised protrusions are operable to separate the reflector from a non-raised portion of the surface of the protective film. 
 
     
     
       2. The display of  claim 1 , wherein the reflector is coupled to the backlight assembly at one or more connection regions. 
     
     
       3. The display of  claim 2 , wherein a density of the plurality of raised protrusions is greater in a first region of the surface of the protective film than in a second region of the surface of the protective film, and wherein a distance between the one or more connection regions and the first region is greater than a distance between the one or more connection regions and the second region. 
     
     
       4. The display of  claim 2 , wherein a size of a first subset of the plurality of raised protrusions is larger than a size of a second subset of the plurality of raised protrusions, and wherein a distance between the one or more connection regions and the first subset of the plurality of raised protrusions is greater than a distance between the one or more connection regions and the second subset of the plurality of raised protrusions. 
     
     
       5. The display of  claim 1 , wherein a size of each raised protrusion in a first subset of the plurality of raised protrusions is larger than a size of each raised protrusion in a second subset of the plurality of raised protrusions. 
     
     
       6. The display of  claim 1 , wherein each raised protrusion in the plurality of raised protrusions has a height between 5-15 μm. 
     
     
       7. The display of  claim 1 , wherein the plurality of raised protrusions are uniformly distributed on the surface. 
     
     
       8. A display device, the device comprising:
 a liquid crystal display comprising:
 a backlight assembly, and 
 a reflector positioned against the backlight assembly; and 
 
 a panel positioned adjacent a surface of the reflector opposite the backlight assembly, wherein the panel comprises a plurality of raised protrusions formed on a surface of the panel adjacent the reflector, wherein the plurality of raised protrusions are operable to separate the reflector from a non-raised portion of the surface of the panel, wherein the plurality of raised protrusions are non-uniformly distributed on the surface of the panel, and wherein a top surface of at least one of the raised protrusions is in contact with the reflector. 
 
     
     
       9. The display device of  claim 8 , wherein the panel comprises a portion of at least one of a heat-spreader, support frame, battery, printed circuit board, or processor. 
     
     
       10. The display device of  claim 8 , wherein a size of each protrusion of a first subset of the plurality of protrusions is larger than a size of each protrusion of a second subset of the plurality of protrusions. 
     
     
       11. A method of manufacturing a panel of a display device, the method comprising:
 forming a plurality of raised protrusions on a first surface of the panel, wherein the plurality of raised protrusions are operable to separate a surface of an at least semi-rigid material in contact with the plurality of raised protrusions from a non-raised surface of the first surface and wherein forming the plurality of raised protrusions on the first surface of the panel comprises applying a patterned protective film to the first surface of the panel. 
 
     
     
       12. The method of  claim 11 , wherein the semi-rigid material comprises a reflector. 
     
     
       13. The method of  claim 11 , wherein the panel comprises a portion of at least one of a heat-spreader, support frame, battery, printed circuit board, or processor. 
     
     
       14. A method of manufacturing a panel of a display device, the method comprising:
 forming a plurality of raised protrusions on a first surface of the panel, wherein the plurality of raised protrusions are operable to separate a surface of an at least semi-rigid material in contact with the plurality of raised protrusions from a non-raised surface of the first surface, wherein the panel comprises metal and wherein forming the plurality of raised protrusions on the first surface of the panel comprises stamping the metal to form the plurality of raised protrusions. 
 
     
     
       15. A liquid crystal display comprising:
 a backlight assembly; 
 a reflector positioned against the backlight assembly; and 
 a protective film covering at least a portion of a surface of the reflector opposite the backlight assembly, wherein the protective film comprises a plurality of raised protrusions formed on a surface of the protective film contacting the reflector, wherein the plurality of raised protrusions are operable to separate the reflector from a non-raised portion of the surface of the protective film, and wherein the plurality of raised protrusions are non-uniformly distributed on the surface.

Description:
FIELD 
     This relates generally to liquid crystal displays (LCDs), and, more specifically, to patterning objects to protect LCD reflector films. 
     BACKGROUND 
     Conventional LCDs operate by projecting light through a layer of liquid crystals and applying varying amounts of electrical charge to the liquid crystals in order to change the color and intensity of the display. Typically, a backlight is used as a source for the light projected through the liquid crystal layer. The backlight generally includes a light source coupled to a light-guide that is oriented toward the layer of liquid crystals. 
     To increase the amount of light directed to the layer of liquid crystals, some backlights include a thin-film reflector attached to the back of the light-guide to reflect stray light toward the liquid crystal layer. While the reflector film improves the quality of the display, the reflector film is very thin and susceptible to damage. For example, the reflector film may occasionally “wet out” against materials placed against or near the reflector film (e.g., a protective poly-film applied to the reflector film or heat-spreader behind the LCD). Here, “wet out” refers to the condition that occurs when the reflector film permanently conforms to the shape of the object that it contacts. 
     Since the backlight supplies the light for an LCD, the quality of the display depends in part on the quality of light produced by the backlight assembly. As a result, damage caused to portions of the backlight assembly, such as the reflector film, may cause a reduction in performance of the LCD. Thus, it is desirable to protect the components of the LCD. 
     SUMMARY 
     This relates to patterning objects (e.g., protective poly-films, heat-spreaders, and other components placed proximate to the backlight of an LCD) with multiple beads or raised protrusions. The beads or protrusions can have a uniform or non-uniform size and can be arranged such that they have a uniform or non-uniform pattern density. The beads or protrusions can be patterned on a surface of the object to provide separation between a non-raised surface of the object and a surface of an adjacent item, such as a reflector film. This can advantageously prevent or reduce damage to the adjacent item caused by the patterned object. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a cross-sectional view of an exemplary LCD according to various embodiments. 
         FIG. 2  illustrates an exemplary connection between a reflector film and a backlight assembly according to various embodiments. 
         FIG. 3  illustrates a cross-sectional view of an exemplary LCD with a protective poly-film according to various embodiments. 
         FIG. 4  illustrates a cross-sectional view of an exemplary patterned protective poly-film according to various embodiments. 
         FIG. 5  illustrates a cross-sectional view of an exemplary LCD with an exemplary patterned protective poly-film according to various embodiments. 
         FIG. 6  illustrates a top-view of an exemplary patterned protective poly-film according to various embodiments. 
         FIG. 7  illustrates a top-view of another exemplary patterned protective poly-film according to various embodiments. 
         FIG. 8  illustrates a top-view of another exemplary patterned protective poly-film according to various embodiments. 
         FIG. 9  illustrates a top-view of another exemplary patterned protective poly-film according to various embodiments. 
         FIG. 10  illustrates a top-view of another exemplary patterned protective poly-film according to various embodiments. 
         FIG. 11  illustrates a top-view of another exemplary patterned protective poly-film according to various embodiments. 
         FIG. 12  illustrates an exemplary process for patterning a protective poly-film according to various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of example embodiments, reference is made to the accompanying drawings in which it is shown by way of illustration specific embodiments that can be practiced. It is to be understood that other embodiments can be used and structural changes can be made without departing from the scope of the various embodiments. 
     This relates to patterning objects (e.g., protective poly-films, heat-spreaders, and other components placed proximate to the backlight of an LCD) with multiple beads or raised protrusions. The beads or protrusions can have a uniform or non-uniform size and can be arranged such that they have a uniform or non-uniform pattern density. The beads or protrusions can be patterned on a surface of the object to provide separation between a non-raised surface of the object and a surface of an adjacent item, such as a reflector film. This can advantageously prevent or reduce damage to the adjacent item caused by the patterned object. 
     In some embodiments, the beads or protrusions can be patterned on a surface of a protective poly-film covering a reflector film to prevent the reflector film from experiencing wet out. In some embodiments, the beads or protrusions can be patterned on a surface of an LCD component adjacent to the reflector film, e.g., a heat-spreader, battery, printed circuit board, processor chip, or the like, to prevent the reflector film from experiencing wet out. These will be described in more detail below. 
       FIG. 1  illustrates a cross-sectional view of a block diagram of an exemplary liquid crystal display (LCD)  100 . In the example shown in  FIG. 1 , LCD  100  can generally include backlight  110  and LCD pane  120 . 
     Since liquid crystals do not emit light on their own, backlight  110  can be used to project light through the LCD crystals contained in LCD pane  120 . Backlight  110  can include light source  111  built into the sides or back of the device for providing the light projected up to LCD pane  120 . Backlight  110  can further include light-guide  113  for directing the light from light source  111  toward LCD pane  120 . In some embodiments, backlight  110  can further include diffuser  115  to disperse the light from light-guide  113  to generate a more uniform light intensity over the display surface of LCD  100 . Backlight  110  can further include one or more prismatic films  117  and  119  for refracting the light from diffuser  115  to collimate the light to the viewer of LCD  100 . 
     To improve light collection, a reflector  101  can be attached to the bottom of backlight  110 . Specifically, reflector  101  can be attached to the bottom of light source  111  and light-guide  113  to reflect light emitted away from LCD pane  120  back through light-guide  113  to LCD pane  120 . Reflector  101  can include any thin-film reflector used in LCD devices. 
     LCD  100  can further include LCD pane  120  for controlling the transmittance of light from backlight  110  to the front of the display. LCD pane  120  can include a pair of polarizers  121  and  129 , which can be separated by a layer of liquid crystals  125  contained in a cell gap between glass plates  123  and  127 . Polarizer  121  can filter the light from backlight  110  by allowing only the portions of the light vibrating in the plane of the optical axis of the polarizer to pass through. 
     While specific embodiments of LCD  100  have been described above, it should be appreciated that other devices may likewise be used, including but not limited to, multi-domain vertical alignment, patterned vertical alignment, in-plane switching, and super-twisted nematic type LCDs. 
       FIG. 2  illustrates a bottom-view of LCD  100  showing the connection regions between reflector  101  and an underlying backlight (such as backlight  110  of  FIG. 1 ) according to various embodiments. Specifically, the shaded regions  201  represent areas where an adhesive can be used to connect reflector  101  to the bottom of the backlight. The adhesive can be applied to the outer portions of the reflector  101  or the backlight to avoid placing adhesive, which can prevent light from being reflected back up to an adjacent LCD pane (such as LCD pane  120  of  FIG. 1 ), in the areas corresponding to the active area of LCD  100 . Thus, in these embodiments, the middle portion  203  of reflector  101  may not be connected to the backlight. This may, in some situations, lead to separation between reflector  101  and the backlight. For example, as illustrated in  FIG. 3 , the middle portion  203  of reflector  101  may sag due to thermal expansion of the reflector or slack in the reflector caused by manufacturing tolerances. 
     As shown in  FIG. 3 , the sag in reflector  101  can cause at least a portion of the reflector  101  (e.g., middle portion  203 ) to contact an object  301  located behind or below the reflector. Object  301  can include, for example, a protective poly-film that is applied to reflector  101  during storage or transportation of backlight  110 . Alternatively, in other examples, object  301  can include a support frame or plate, heat-spreader, battery, printed circuit board, processor chip, or the like, located behind backlight  110  in a device incorporating LCD  100 . If reflector  101  remains in contact with object  301  for a sufficiently long period of time, reflector  101  may “wet out” against object  301 . In other words, reflector  101  may permanently conform to the shape of object  301 . This can result in a reduction in performance of backlight  110 , and, consequently, LCD  100 . 
     To prevent the reflector from experiencing wet out, a patterned protective poly-film according to various embodiments can be used to cover the reflector, thereby providing separation from components adjacent thereto. 
       FIG. 4  illustrates a cross-sectional view of patterned protective poly-film  400  that can be used, for example, to cover reflector  101  during storage or transport of backlight  110  or can be used to permanently cover reflector  101 . Patterned protective poly-film  400  can include beads or raised protrusions  403  distributed on a surface of the film. Protrusions  403  can be included to separate the non-raised surface  405  of protective poly-film  403  from another surface, such as a surface of reflector  101 . For instance, as shown in  FIG. 5 , the tops of protrusions  403  can contact reflector  101  and separate the non-raised surface  405  of patterned protective poly-film  400  from reflector  101 . Since only the top portions of protrusions  403  contact reflector  101 , only small, discrete regions of reflector  101  can contact patterned protective poly-film  400 . This can eliminate, or at least reduce, the wet out effect experienced by reflector  101  when used with protective poly-films. 
     The size of the beads or raised protrusions  403  can be varied based on the specific application. For example, in some embodiments, protrusions  403  can have a width and height between 5 and 15 μm. However, it should be appreciated that protrusions of any size can be used depending on the thickness and material used to form reflector  101  and the thickness and material used to form patterned protective poly-film  400 . For instance, protrusions  403  having a larger height can be used for a reflector  101  formed of a thinner or softer material. This can be done to prevent reflector  101  from contacting the non-raised surface  405  of patterned protective poly-film  400  that would otherwise occur due to the increased amount of sag experienced by a thinner or softer reflector  101  between protrusions  403 . Alternatively, or in addition, protrusions  403  having a larger width can be used for reflectors  101  formed of a thinner or softer material to provide additional support for reflector  101 . This can reduce the amount of deformation experienced by a thinner or softer reflector  101 . Conversely, protrusions  403  having a smaller height, smaller width, or both, can be used for reflectors  101  formed of a thicker or stiffer material because less sag may occur in these reflectors  101  between protrusions  403  and less support may be needed for the reflector. 
     In some embodiments, the height and width of protrusions  403  can also be varied in a similar manner based on the thickness and material used for protective poly-film  400 . For instance, since the non-raised surface  405  of patterned protective poly-film  400  can sag towards reflector  101  in manner similar to the way that reflector  101  sags towards patterned protective poly-film  400 , protrusions  403  having a larger height, larger width, or both, can be used for a patterned protective film  400  formed of a thinner or softer material. Conversely, protrusions  403  having a smaller height, smaller width, or both, can be used for patterned protective poly-film  400  formed of a thicker or stiffer material because less sag may occur in these patterned protective poly-films  400  between protrusions  403  and less support may be needed. 
     The distributions of protrusions  403  can also be varied based on the specific application. In some embodiments, protrusions can be uniformly, or at least substantially uniformly distributed on a surface of patterned protective poly-film. For example, distances between adjacent protrusions can be within 5% of each other due to manufacturing tolerances. 
       FIG. 6  illustrates a top-view of patterned protective poly-film  600  having multiple protrusions  603  uniformly distributed across its surface. The average density of protrusions  603  can vary depending on the thickness of reflector  101 , the material used to form reflector  101 , the thickness of patterned protective poly-film  600 , the material used to form patterned protective poly-film  600 , and the size of protrusions  603 . For instance, higher densities of protrusions  603  can be used for a reflector  101  formed of a thinner or softer material. This can be done to compensate for the increased amount of sag that may occur in reflector  101  between protrusions  603 . Additionally, higher densities of protrusions  603  can be used with smaller protrusions  603  to prevent reflector  101  from contacting the non-raised surface of the patterned protective poly-film due to the reduced distance between the top of protrusions  603  and the non-raised surface of the patterned protective poly-film. Conversely, lower densities of protrusions  603  can be used for a reflector  101  formed of a thicker or stiffer material because less sag may occur in the reflector  101  between protrusions  603 . Additionally, lower densities of protrusions  603  can be used with larger protrusions to prevent reflector  101  from contacting the flat portion of patterned protective poly-film  600  due to the increased distance between the top of protrusions  603  and the non-raised surface of the patterned protective poly-film. 
     In some embodiments, the distributions of protrusions  603  can also be varied in a similar manner based on the thickness and material used for protective poly-film  600 . For instance, since the non-raised surface of patterned protective poly-film  600  can sag towards reflector  101  in manner similar to the way that reflector  101  sags towards patterned protective poly-film  600 , higher densities of protrusions  603  can be used for a patterned protective film  600  formed of a thinner or softer material. Conversely, lower densities of protrusions  603  can be used for patterned protective poly-film  600  formed of a thicker or stiffer material because less sag may occur in these patterned protective poly-films  600  between protrusions  603  and less support may be needed. 
     In other embodiments, protrusions can be non-uniformly distributed on a surface of a patterned protective poly-film. For example,  FIG. 7  illustrates a top-view of patterned protective poly-film  700  having multiple protrusions  703  that are non-uniformly distributed across its surface. In some embodiments, patterned protective poly-film  700  can attach to a reflector that is connected to a backlight in a manner similar to that shown in  FIG. 2 . Thus, in these embodiments, patterned protective poly-film  700  can have a higher density of protrusions  703  near the center of the film to compensate for the increased amount of sag expected in that area. Patterned protective poly-film  700  can have a lower density of protrusions  703  near the sides of the film since this is the region that the reflector is attached to the backlight, and, as such, less sag is expected in these areas. 
     While specific examples are provided above, protrusions  703  can be distributed in other patterns based on the connection regions between the protective film and reflector. For example, if the reflector is also connected to the backlight at the top and bottom of the film, the protrusion density near those locations can also be lower. Generally, in some embodiments, the density of protrusions can increase as the distance between the protrusion and the connection region increases. 
     In other embodiments, both the density and size of protrusions can be varied on the surface of the protective poly-film. For example, the density of the protrusions can be higher and the size of the protrusions can be larger in areas that are farther away from the connection regions between the reflector and backlight. Similarly, the density of the protrusions can be lower and the size of the protrusions can be smaller in areas that are closer to the connection regions between the reflector and backlight. Thus, in some embodiments, the density of the protrusions can become increasingly higher and the size of the protrusions can become increasingly larger as the distance between the protrusion and the connection region increases. 
     It should be appreciated that the determination of an appropriate size and pattern of beads or protrusions for a given application can be an iterative process. Using the factors described above, one of ordinary skill in the art would understand how to vary the size and pattern of protrusions to determine an effective pattern to be used on a surface for any given application. Additionally, while example patterns of protrusions have been provided above, it should be appreciated that other designs, such as circles, horizontal lines, vertical lines, diagonal lines, and the like, may be used. 
     For example, in some embodiments, the protrusions used for the patterned protective film can include ridges arranged in various patterns.  FIG. 8  illustrates a top-view of patterned protective poly-film  800  having multiple protrusions  803 . The protrusions  803  can include multiple raised ridges arranged in a uniform vertical pattern. Similarly,  FIG. 9  illustrates a top-view of patterned protective poly-film  900  having multiple protrusions  903 . The protrusions  903  can include multiple raised ridges arranged in a non-uniform horizontal pattern.  FIG. 10  illustrates a top-view of patterned protective poly-film  1000  having multiple protrusions  1003 . The protrusions  1003  can include multiple raised ridges arranged in a uniform diagonal pattern.  FIG. 11  illustrates a top-view of patterned protective poly-film  1100  having multiple protrusions  1103 . The protrusions  1103  can include multiple raised ridges arranged in concentric non-uniform ovals. 
     In some embodiments, the protrusions can be formed of the same material as the patterned protective poly-film. In these embodiments, the patterned protective poly-film can be formed by exemplary process  1200  in  FIG. 12 . At block  1201  of process  1200 , poly-film material (e.g., a roll of poly-film) can be patterned to have multiple protrusions, such as protrusions  403 . The poly-film material can be patterned by rolling a roller having a patterned surface across the poly-film or by stamping the poly-film with a press or plate having a patterned surface. In some examples, the surfaces of the roller or stamp can include protrusions configured to produce corresponding protrusions in the poly-film when pressed against the poly-film. In other examples, the surfaces of the roller or stamp can include dimples configured to produce corresponding protrusions in the poly-film when pressed against the poly-film surface. In this manner, the poly-film material can be rolled or stamped to have protrusions having a desired size, shape, and density. As a result, protrusions made of the same material as the poly-film can be formed on the surface of the poly-film material. At block  1203 , the patterned poly-film can be cut using, for example, a die cutter, to form protective poly-film sheets having a desired shape and size. The resulting patterned protective poly-film can then be applied to a reflector as described above. In other embodiments, the actions performed at blocks  1201  and  1203  can be reversed. Specifically, the poly-film can be cut into sheets having a desired shape and size and may then be patterned to generate the desired pattern of protrusions. Alternatively, pre-cut protective poly-film sheets may be patterned to generate the desired pattern of protrusions. 
     While the patterning process has been described above with respect to protective poly-films, it should be appreciated that the patterning technology can be applied to other objects. For example, objects within a device housing an LCD can be patterned to prevent wet out of the backlight reflector. Specifically, the panel behind the LCD and adjacent to the reflector can be patterned to provide separation between surfaces of the object and the reflector. Since these panels can be formed of various materials, such as metal, plastic, graphite, and the like, other patterning processes can be used. For example, depending on the material to be patterned, stamping, laser patterning, or other known processes for manipulating the surface of the material can be used to form the multiple protrusions having sizes and pattern distributions as described above for the patterned protective poly-film. In some embodiments, instead of patterning the object behind the LCD, a patterned protective poly-film, such as patterned protective poly-film  400 , can be applied to the object. 
     In these embodiments, the dimensions and distribution of protrusions on the object or patterned protective film applied to the object can further depend on the clearance desired between the reflector and the object, the material used to form the object, and the shape or design of the object. For example, larger protrusions can be used when a larger clearance is required between the reflector and the object, while smaller protrusions can be used when a smaller clearance is required. Additionally, the size and distribution pattern of protrusions can vary based on the material, shape, and design of the object in a manner similar to that described above based on the material and thickness of reflector  400 . 
     Although embodiments have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the various embodiments as defined by the appended claims.

Metadata:
Filing Date: 20110617
Publication Date: 20150217
Grant Date: 20150217
Priority Date: 20110617
Inventors: WURZEL JOSHUA G.
MARTISAUSKAS STEVEN J.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B6/0081", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49002", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0055", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0093", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0093", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0081", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/0055", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 47353418