Abstract:
Disclosed herein are structures and methods for assembling said structures to provide a glass-based and flush implementation of a display structure for a vehicle-based context. Employing the aspects disclosed herein, an implementer is provided a structure capable of passing head-impact tests, while prevent stray shard creation and providing an aesthetically superior design to convention implementation.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This patent application claims priority to U.S. Provisional Application No. 62/351,455, filed Jun. 17, 2016, entitled “HEAD IMPACT RESISTANT GLASS LENS CONSTRUCTION METHOD,” now pending. This patent application contains the entire Detailed Description of U.S. Provisional Patent application No. 62/351,455. 
     
    
     BACKGROUND 
       [0002]    As displays are utilized more often in automotive applications, the use of touch lenses in front of the display is becoming more prevalent. These touch lenses may either have an air gap between the display and the touch lens, or be optically bonded to the display. 
         [0003]    There is also a desire to provide a flush touch lens appearance as demonstrated in many mobile devices currently available. This is superior to a “picture frame” type geometry that has a raised wide border above the surface of the touch surfaces. 
         [0004]      FIG. 1( a )  illustrates an example of a flush mobile device  100 , with a bezel  102  and a touch screen  101 . As shown, the bezel  102  and the touch screen  101  are substantially level, thereby providing a smooth interface. 
         [0005]    On the contrary,  FIG. 1( b )  illustrates a mobile device  110 , with a raised bezel  112  and a touch screen  111 . The device  110  is considered less favorable, as it is considered to be less aesthetically pleasing to an end consumer of the mobile device. 
         [0006]    Automotive touch lens applications have regulatory safety requirements depending on the location in the vehicle. In general, in order to achieve a flush appearance and pass automotive head impact testing, such as ECE21 &amp; FMVSS201, most solutions require the use of a plastic substrate lens in order to prevent hazardous glass sharp edge exposure and expulsion. However there is a desire to use a glass front lens for a thinner more rigid structure with superior optical characteristics. It is generally considered very risky to use an exposed glass lens. Although a thin plastic film has be applied to the front surface to contain glass shards under a head impact event, generally there is a problem with sharp edges or detached glass expulsion around the perimeter of the part. 
       SUMMARY 
       [0007]    The following description relates to a display structure with a flush appearance for a vehicle-based implementation. Exemplary embodiments may also be directed to any of the system, the method, or an application disclosed herein, and the manufacture and assembly of the same. 
         [0008]    Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. 
         [0009]    A display structure for a vehicle. The display includes a glass substrate with a tapered edge; an in-molded plastic part, molded to conform around the tapered edge; a laminated plastic film disposed to overlap the glass substrate and the in-molded plastic part, wherein the laminated plastic film is on a surface opposing a viewer of the display structure. 
         [0010]    In another example, the in-molded plastic part is a one-piece structure. 
         [0011]    In another example, the in-molded plastic part is a two-piece structure. 
         [0012]    In another example, the display includes a gasket, and the gasket is configured to absorb a load placed on the display. 
         [0013]    In another example, the laminated film has a coating. 
         [0014]    In another example, the laminated film may be defined as one of the following: anti-reflective (AR) coating, anti-glare (AG) coating, both anti-reflective (AR) coating and anti-glare (AG) coating, with black printing, and anti-fingerprint coating. 
         [0015]    In another example, the black printing may be further defined as one of: infrared (IR) transmissive ink or low conductive inks for capacitive touch applications. 
         [0016]    Also disclosed herein are methods for assembling the structures. 
         [0017]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0018]    The detailed description refers to the following drawings, in which like numerals refer to like items, and in which: 
           [0019]      FIGS. 1( a ) and ( b )  illustrate example mobile device according to conventional designs; 
           [0020]      FIGS. 2( a ) and ( b )  illustrate an overview of the head impact test and examples of results; 
           [0021]      FIGS. 3( a ) and ( b )  illustrate an exemplary embodiment according to the aspects disclosed herein; and 
           [0022]      FIG. 4  illustrates an example method for implementing the structures of  FIGS. 3( a ) and ( b ) . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The invention is described more fully hereinafter with references to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. It will be understood that for the purposes of this disclosure, “at least one of each” will be interpreted to mean any combination the enumerated elements following the respective language, including combination of multiples of the enumerated elements. For example, “at least one of X, Y, and Z” will be construed to mean X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g. XYZ, XZ, YZ, X). Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals are understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience. 
         [0024]    It is an object of the proposed solution to simultaneously pass the following requirements: 
         [0025]    1) Compliance with automotive safety standards; 
         [0026]    2) Satisfying craftsmanship (or aesthetic) demands;
       a. Providing a flush thin border customer perceived appearances;   b. Providing higher stiffness compared to plastic substrate solutions;       
 
         [0029]    3) Providing optical performance, such as those achieved with the implementation of glass;
       a. Low birefringence—birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive);       
 
         [0031]    4) Maintenance of linearly polarized light emission. 
         [0032]    The actual regulatory specifications for passing ECE21 &amp; FMVSS201 (or other standards not disclosed) are quite complex so a simplified explanation will be given.  FIG. 2( a )  illustrates a typical head impact test. As shown, a crash test dummy  200  is accelerated into a surface (head form)  210  to produce a shattered piece  220 . 
         [0033]    In performing the test shown in  FIG. 2( a ) , there are two primary requirements that must be satisfied: 
         [0034]    1) Energy Absorption—at the vehicle level, an accelerometer equipped device that simulates an occupant&#39;s head makes contact with the instrument panel. The deceleration of the head form shall not exceed 80 (acceleration of gravity) g continuously for more than 3 milliseconds (ms); and 
         [0035]    2) Sharp Edges: head form tested items shall not contain any dangerous roughness or sharp edges likely to increase the risk of serious injury to the occupants. This can include broken edges after test as well as detachment of pieces during the test. ECE21 has additional restriction on radius and projection heights of objects that FMVSS 201 does not specify. 
         [0036]    In general, the energy absorption criterion is satisfied by engineered deformation of the various components in the instrument panel. Ductile materials that can deform without breaking are generally used for appearance items which often favor impact resistant plastics. If more brittle materials (i.e. likely to shatter into numerous pieces) are desired like glass, the deformation must be strictly limited to avoid breakage. This reduces energy absorption of that component and places a burden on other components in the instrument panel to work within the  80   g  limit noted above as a requirement for several tests. 
         [0037]    As shown in  FIG. 2( b ) , five different permutations ( 251 - 255 ) of a head form  210  is shown. As shown, a top surface  260  is shown (e.g. a film or cover), along with a lens surface  270 . In the examples shown, cases  280  are considered passing tests, while cases  290  are seen as failed tests. The reason for this is that the cases shown in  290  results in shards being created that may be projected towards a driver or passenger in a vehicle. 
         [0038]    Disclosed herein are structures and methods for providing a flush appearance employing glass substrates for a vehicle-based display structure. The structures and the methods for implementing said structures exhibit superior qualities with regards to head-impact testing. 
         [0039]      FIGS. 3( a ) and ( b )  illustrate an example of the structures disclosed herein. These structures (which are alternate embodiments) will be described in greater detail along with the method  400  shown in  FIG. 4 . The method  400  explains the assembly of the various elements in the structures shown in  FIGS. 3( a ) and ( b ) . 
         [0040]    The method  400  first requires to the provision of a glass substrate  302  (operation  410 ). This glass substrate  302  is tapered at the edges  331  to allow fitting with an in-molded structure ( 420 ). 
         [0041]    As explained above, the tapered edges are surrounded with an adaptation of an in-mold plastic border around the perimeter of the glass substrate  302  (operation  430 ).  FIG. 3( a )  illustrates a two-piece embodiment (with in-mold resin  311  and part  310  additionally provided), while  FIG. 3( b )  illustrates a one-piece embodiment ( 330 ). In either case, a gasket  320  is provided. The gasket  320  may be of a rubber-type or elastomeric material, and be provided so as to absorb a load that may hit the plastic film during an accident or impact. 
         [0042]    In operation  440 , a plastic film  301  is laminated and provided over the in-molded plastic frame ( 311  or  330 ) and the glass interface ( 302 ). The lamination and provision of the plastic film  301  ensures that glass shards are contained in response to impact (such as those shown in  FIG. 2( a ) ). 
         [0043]    The molded plastic frame ( 311  and  330 ) and its mating with the glass substrate  302  also aids in avoiding exposure of glass edges. Alternatively, or in addition to, more impact resistant materials for the frame (elastomeric materials like TPE or others) would provide further improvement of the frame to avoid breakage during impact. 
         [0044]    As shown above, the film  301  overlaps a glass substrate  302  and a plastic element ( 311  or  330 ). The problem in conventional designs has been the edges. If film over the glass is only brought to the glass to the edge, shards explode out of the edge. The cross sections shown in  FIGS. 3( a ) and ( b )  illustrate how the frame through the introduction of ledge  332  hides the edge of the film  301 . Thus, the aesthetics are improved, as well as avoiding a film edge that could be picked at by consumers. 
         [0045]    Applicants have performed tests with the above-described structures, and have achieved no delamination problems between the border layers ( 311  or  330 ) and the glass substrate  302 . 
         [0046]    Employing the aspects disclosed herein, and especially focusing on the use of a glass substrate (as opposed to a plastic substrate) has shown improved stiffness compared to plastics due to an increased modulus of elasticity. In one example, the following results are used: 
         [0047]    Glass Modulus of Elasticity ( 302 ): 75 Gpa; 
         [0048]    Optical Plastic Modulus of Elasticity ( 310 / 311  or  330 ): 2.3 Gpa; 
         [0049]    For a given geometry and thickness, glass has 75/2.3=32.6 times the stiffness. By employing the ratio above, Applicants have discovered that said ratio prevents display push mura defects for direct bonded displays, and promotes an overall improved aesthetic display for glass lens. Furthermore, a dielectric properties and thickness of glass employed in this scenario provides for an improved touch capability of the display. 
         [0050]    The front films may be based on a TAC substrate with an optical adhesive. The optical adhesive employed achieves a passage of head impact testing with bezel protection around the edge to contain edge shards. The adhesive is aids in-head impact testing compliance. By employing the concepts disclosed, the adhesive is separate-able, and thus allows the glass to break without tearing the film. 
         [0051]    The films employed herein may have a variety of surface coatings to enhance both optical and mechanical performance such as:
       Anti-reflective (AR) coating   Anti-glare (AG) coatings with superior performance to glass AG coatings   AGAR coatings (black printing  340 )   Anti-fingerprint or anti-smudge coatings       
 
         [0056]    The black printing  340  may be of any type of ink including the use of IR transmissive ink or low conductive inks for capacitive touch applications. It should be noted that the disclosed structures optical stackup configuration provides low optical retardation (birefringence) compared to plastic lens solutions which is important for display view-ability with polarized sunglasses. Current art using high impact grade optical plastic lens either has relatively high birefringence with poor polarized sunglass view-ability or requires additional specialty optical films in the form of super retardation films (SRF) with very high retardation behind the plastic lens to scatter the plastic lens retardation to the polarized sunglass user. SRF films reduce optical transmission and disrupt the linear polarization of the display which can have adverse effects in the vehicle in the form of increased scattering of light on windshields. 
         [0057]    The proposed head impact resistant lens construction method allows the use of a glass lens which will pass automotive head impact testing. Some of the benefits are:
       Head impact compliance   Improved substrate optical properties   Improved craftsmanship   Front surface coating film flexibility   Improved glass attachment       
 
         [0063]    As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.