Abstract:
A strengthened cover lens is disclosed to include a substrate, including an upper surface, a lower surface substantially parallel to the upper surface, a side surface located between the upper surface and the lower surface, and the side surface being substantially perpendicular to the upper surface and the lower surface, an upper chamfer surface formed between the upper surface and the side surface and the upper chamfer surface being adjacent the side surface, a concave portion formed between the upper surface and the upper chamfer surface, and a protection layer covering at least the concave portion and the upper chamfer surface, and a method for strengthening a cover lens being durable for abrasive condition by rigid body such as metal in common use is also provided.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The disclosure relates to a strengthened cover lens and methods for strengthening a cover lens. More particularly, the disclosure relates to a strengthened cover glass with a polymer coating layer partially covering a side of substrate in a specific way to increase strength of edges of cover lens. 
         [0003]    2. Description of the Related Art 
         [0004]    Because of touch glasses are vulnerable to be broken from chippings, cracks and flaws at the edge caused by strong contacts with rigid bodies such as hard metals or the similar hard material which leads function loss of the touch glasses. 
         [0005]    Various structures have been used to increase the strength of glass surfaces by modifying the shape and size, and generally coated a layer to side surfaces of a glass article to protect the glass from external impact. 
         [0006]    In addition, conventionally coated polymer covers sides without an upper part of the edges, and the protection effect increased as the thickness of coated polymer increased. However, the protection ability might be better at 100 μm or more of the thickness of the coated polymer, but process capability index Cpk may not meet 1.33 under the situation. 
       SUMMARY OF THE INVENTION 
       [0007]    In view of the aforementioned existing technical problems, one purpose of the present invention is to provide a strengthened cover lens and a method for strengthening a cover lens. 
         [0008]    According to an aspect of the present invention, a strengthened cover lens is provided, comprising a substrate, comprising: an upper surface; a lower surface substantially parallel to the upper surface; a side surface located between the upper surface and the lower surface, and the side surface being substantially perpendicular to the upper surface and the lower surface; an upper chamfer surface formed between the upper surface and the side surface and the upper chamfer surface being adjacent the side surface; a concave portion formed between the upper surface and the upper chamfer surface; and a protection layer may cover at least the concave portion and the upper chamfer surface. 
         [0009]    Preferably, the substrate may further comprise a lower chamfer surface between the lower surface and the side surface. 
         [0010]    Preferably, the protection layer may further cover the side surface. 
         [0011]    Preferably, the protection layer may comprise polymer resin, and a resin hardness of the protection layer is durometer hardness of A80 to A100. 
         [0012]    Preferably, an angle between the upper chamfer surface and the side surface may be about 135 degree. 
         [0013]    Preferably, a first thickness from an outer periphery of the protection layer straight to the upper chamfer surface may be within a range between about 30 μm to about 40 μm. 
         [0014]    Preferably, a second thickness from an outer periphery of the protection layer straight to the side surface may be within a range between about 60 μm to about 80 μm. 
         [0015]    Preferably, a distance from an inner edge of the concave portion straight to an imaginary line through an outermost point on the outer periphery may be in a range of about 100 μm to about 150 μm. 
         [0016]    Preferably, an edge of the cover lens may have a value of B10 above 550 MPa in 4-point bending test. 
         [0017]    According to another aspect of the present invention, a method for strengthening a cover lens is provide, the method comprising: providing a substrate, the substrate comprising an upper surface, a lower surface substantially parallel to the upper surface, and a side surface locating adjacent to the upper surface and the lower surface, and substantially perpendicular to the upper surface and the lower surface; forming an upper, chamfer surface between the upper surface and the side surface; covering acid-resistant layers on the upper surface and the lower surface, wherein the acid-resistant layer on the upper surface have defined a region for a concave portion on the edge of the upper surface which is predetermined to be etched; acid-etching the upper surface of the glass article to form a concave portion between the upper surface and the upper chamfer surface; and coating a protection layer to cover at least the concave portion and the side surface using a coating source in a coating direction. 
         [0018]    Preferably, the coating direction is tilted with an tilt angle relative to an imaginary line from the lower surface straight to the upper surface in a cross-section view, a horizontal component of the coating direction is from the outside to the inside of the upper surface, and a vertical component of the coating direction is from the upper surface to the lower surface, and the tilt angle is in a range from about 30 degree to about 60 degree. 
         [0019]    Preferably, the using of the coating source may comprise a needle injection, a jet spray, or drum type coating. 
         [0020]    Preferably, the forming of the upper chamfer surface may further comprise the forming of a lower chamfer surface between the lower surface and the side surface. 
         [0021]    Preferably, the protection layer further covers and the side surface. 
         [0022]    Preferably, the protection layer comprising polymer resin, and a resin hardness of the protection layer is durometer hardness of A80 to A100. 
         [0023]    Preferably, an angle between the upper chamfer surface and the side surface is about 135 degree. 
         [0024]    Preferably, a first thickness from an outer periphery of the protection layer straight to the upper chamfer surface is up to a range between about 30 μm to about 40 μm. 
         [0025]    Preferably, a second thickness from an outer periphery of the protection layer straight to the side surface may be within a range between about 60 μm to about 80 μm. 
         [0026]    Preferably, a distance from an inner edge of the concave portion straight to an imaginary line through an outermost point on the outer periphery the side surface may be in a range of about 100 μm to about 150 μm. 
         [0027]    Preferably, an edge of the cover lens may have a value of B10 above 550 MPa in 4-point bending test. 
         [0028]    As the aforementioned description, the present invention provides a strengthened cover lens and a method for strengthening a cover lens solve the problems concerning that conventional side-coated glass such as 6 face strengthening glass for cover lens and 2 face strengthening glass, one glass sensor, glass-glass structure, was apt to be broken due to stress caused by cracks and defects created during chipping process of glass substrates. The method for strengthening a cover glass also provide a cover lens with a specific profile for side surface to ensure the shape of the protection layer is firmly served as a buffer on the side of the cover lens. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a perspective view schematically illustrating a strengthened cover lens according to exemplary embodiments. 
           [0030]      FIG. 2  is a cross-sectional view from a side of the strengthened cover lens in  FIG. 1 . 
           [0031]      FIG. 3  is a flow chart subsequently illustrating an edge shaping method for polymer coating to strengthen a cover lens. 
           [0032]      FIG. 4A  to  FIG. 4G  are cross-sectional views schematically illustrating each step of the method for strengthening a cover lens, according to the present invention. 
           [0033]      FIG. 5  is a cross-sectional view from a side of a strengthened cover lens according to another exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can realize the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
         [0035]    In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various exemplary embodiments. It is apparent, however, that various exemplary embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring various exemplary embodiments. 
         [0036]    In the accompanying figures, the size and relative sizes of layers, films, panels, regions, etc., may be exaggerated for clarity and descriptive purposes. Also, like reference numerals denote like elements. 
         [0037]    When an element or layer is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or layers may be present. When, however, an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. For the purposes of this disclosure, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be constructed as X only, Y only, Z only, or any combination of two or more of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0038]    Although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, and/or section from another element, component, region, layer, and/or section. Thus, a first element, component, region, layer, and/or section discussed below could be termed a second element, component, region, layer, and/or section without departing from the teachings of the present disclosure. 
         [0039]    Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for descriptive purposes, and, thereby, to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the drawings. Spatially relative terms are intended to encompass different orientations of an apparatus in use, operation, and/or manufacture in addition to the orientation depicted in the drawings. For example, if the apparatus in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and, as such, the spatially relative descriptors used herein interpreted accordingly. 
         [0040]    The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms, “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Moreover, the terms “comprises,” “comprising,” “includes,” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0041]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense, unless expressly so defined herein. 
         [0042]    A strengthened cover lens and a method for strengthening a cover lens are provided. The strengthened cover lens includes a substrate with an upper surface, a lower surface, and a side surface, wherein an upper chamfer surface forms between the upper surface and the side surface. A concave portion is formed between the chamfer surface and the side surface of the substrate, and a protection layer covers at least the concave portion and the side surface to strengthen the edge of the cover lens. The method comprises providing a cover lens including a substrate, the substrate having a side surface, modifying the side surface by acid-etching portions without acid-resistant, coating a protection layer to cover at least a portion of the surface using a coating source with an angle relative to a vertical imaginary line, thereby strengthening the edge of the cover lens. Although only one surface of the may be described herein, it is understood that, unless otherwise specified, the method described herein is applicable to one or more surfaces of a cover lens. 
         [0043]      FIG. 1  is a perspective view schematically illustrating a strengthened cover lens according to exemplary embodiments, and  FIG. 2  is a cross-sectional view from a side of the strengthened cover lens in  FIG. 1 . 
         [0044]    One embodiment of the strengthened cover lens is schematically shown in  FIG. 1  and  FIG. 2 . As shown in  FIG. 1 , a strengthened cover lens  1  including a substrate  100 . The substrate  100  comprises an upper surface  101 , a lower surface  102  which is substantially parallel to the upper surface  101 , and a side surface  103  located between the upper surface  101  and the lower surface  102 . Here, the substrate  100  may include various type of cover glass or touch sensor fabricated by transparent materials, such as, but not limit to, glass or plastic substrate. The substrate  100  can further include electrically active layers, such as those comprising dielectric or conductive materials used in the manufacture of touch screens, panels, or displays. The substrate  100  can also be used as a touch screen, a touch panel, a display panel, a window, a display screen, a cover plate, a casing, or an enclosure for electronic communication and entertainment devices, such as games, cell phones, music, and DVD players and the like, as well as for information terminal devices, such as laptop computers and the like. 
         [0045]    The substrate  100  further comprises an upper chamfer surface  104  formed between the upper surface  101  and the side surface  103  with an angle θ 1  formed between the upper chamfer surface  104  and the side surface  103 . And a concave portion  105  is formed between the upper surface  101  and the upper chamfer surface  104 . In a preferable embodiment in the present invention, the angle θ 1  may be about 135 degrees, but not limited to, the angle θ 1  may be various appropriate angles. The concave portion  105  is formed between the upper surface  101  and the upper chamfer surface to provide a space for a protective coating to protect an upper edge of the substrate. 
         [0046]    A protection layer  106  is arranged to cover the concave portion  105 , the upper chamfer surface  104 , and the side surface  103 . The protection layer  106  has an outer periphery  108 . The distance between the outer periphery  108  and the upper chamfer surface  104  is denoted as a first thickness T 1 . The distance between the outer periphery  108  and the side surface  103  is denoted as a second thickness T 2 , the distance from an edge point straight to an vertical imaginary line L 1  through the outermost point on the outer periphery  108  is denoted as a third thickness T 3  in  FIG. 2 . The Amount of the first thickness T 1  and second thickness T 2  depends on viscosity and hardness of material used for the protection layer  106 . Temperature, humidity, and surface tension during processes for forming the protection layer  106 , in other words, the above properties control the shape of the protection layer  106 . Although effects in strengthening the cover lens increase as the first thickness T 1  and the second thickness T 2 , however, a process capability index Cpk of the cover lens  1  will be limited by the thickness of the protection layer  106 . For example, when an average thickness of a coating layer on a round shape side surface on edges of a glass article generally used in conventional glass strengthening structure is about 100 μm, the cover lens can&#39;t meet the process capability index Cpk 1.33. In one preferable embodiment of the present invention, the first thickness T 1  may be within a range of about 30 μm to about 40 μm. In another preferable embodiment of the present invention, the second thickness T 2  may be within a range of about 60 μm to about 80 μm. In a still another preferable embodiment, the third thickness T 3  may be within a range of about 100 μm to about 150 μm. 
         [0047]    Materials for the protection layer  106  according to the present invention may be selected from various themo-polymerizable resins, such as acrylic thermosetting resins, thermo-curable PU resins, or thermo-curable epoxy resins. The thermo-polymerizable resins are not described in detail here as they are well-known in the art. Other materials may also be used to produce the protection layer  106  according to the present invention, as long as it has appropriate viscosity and hardness and can be affixed to the substrate  100 , and may be utilized in the coating process. The protection layer  106  not only serves as a buffer for edges of the cover lens  1  to avoid edge effect, but also reduces or even eliminate the focus of micro-cracks as a starting point where the stress affects. The protection layer  106  may be effective to absorb vibration generated by external force and to reduce the impact. In one preferable embodiment of the present invention, a resin hardness of the protection layer  106  is durometer hardness of A80 to A100. 
         [0048]      FIG. 3  is a flow chart subsequently illustrating an edge shaping method for polymer coating to strengthen a cover lens, and  FIG. 4A  to  FIG. 4G  are cross-sectional views schematically illustrating each step of the method for strengthening a cover lens, according to the present invention. 
         [0049]    Referring to  FIG. 3  and  FIG. 4A  to  FIG. 4G , subsequently shows steps of a method for strengthening a cover lens a method for strengthening a cover lens according to the present invention. The method includes the step of: providing a substrate  400 , the substrate  400  comprising an upper surface  401 , a lower surface  402  substantially parallel to the upper surface  401 , and a side surface  403  locating between the upper surface  401  and the lower surface  402 , wherein the side surface  403  is substantially perpendicular to the upper surface  401  and the lower surface  402  (Step S 31 ); forming an upper chamfer surface  404  between the initial upper surface  401  with an angle θ 2  between the upper chamfer surface  404  and a chamfered side surface  403 ′, and forming a lower chamfer surface  407  between the initial lower surface  402  and the initial side surface  403  (Step S 32 ), wherein a chamfered upper surface  401 ′ and a chamfered lower surface  402 ′ are formed after the forming of the upper chamfer surface  404  and the lower chamfer surface  407  is completed. Here, the forming of the upper chamfer surface  404  and the lower chamfer surface  407  may use those means known in the art, such as scribing and breaking, mechanical cutting, laser cutting, or the like. In a preferable embodiment in the present invention, the angle θ 2  may be about 135 degree to provide a suitable tilt angle for subsequent process, but not limited to, the angle ν 2  may be various appropriate angles. 
         [0050]    Next, covering a upper acid-resistant layer  410  on the chamfered upper surface  401 ′ and a lower acid-resistant layer  420  on the chamfered lower surface  402 ′ (step S 33 ), wherein the upper acid-resistant layer  420  on the chamfered upper surface  401 ′ have defined a region R 1  for a concave portion on the edge of the upper surface which is predetermined to be etched. The acid resistant layers may include acid-resistant material generally for protecting glass from being etched by etchant, and may be changed in accordance with material of the substrate and corresponding etchant. The acid-resistant material may be formed on the processing surface by spin coating, chemical vapor deposition (CVD), atomic layer deposition (ALD), molecular layer deposition (MLD), and the like. The acid-resistant layers on the chamfered upper surface  401 ′ and the chamfered lower surface  402 ′ each with different lengths to define the start-point of etching. 
         [0051]    Acid-etching the chamfered upper surface  401 ′ of the substrate  400  is then be performed to form a concave portion  405  between the chamfered upper surface  401 ′ and the upper chamfer surface  404  (step S 34 ), an etched upper surface  401 ″ and an etched upper chamfer surface  404 ′ are formed after the forming of the concave portion  405  is completed. The lowest point of concave portion  405  may preferable be higher than the etched upper chamfer surface  404 ′ to provide a smooth portion for subsequent process. The acid-etching may be performed using any suitable acid such as an etchant comprised hydrofluoric acid, a mineral acid, an organic acid, combination thereof, and the like, and the etchant should be suitable for the material of the substrate  400 . 
         [0052]    Next, coating a protection layer to cover the concave portion  405  and the chamfered side surface  403 ′ by a coating source  430  arranged in a coating direction Dc (step S 35 ), the coating direction Dc is tilted with an tilt angle θ 3  relative to an imaginary line L 2  from the chamfered lower surface  402 ′ straight to the etched upper surface  401 ″ in a cross-sectional view. The horizontal component Dch of the coating direction is from the outside to the inside of the substrate  400  along a horizontal direction D 1 , and the vertical component Dcv of the coating direction is from the etched upper surface  401 ″ straight to the chamfered lower surface  402 ′. In a preferable embodiment of the present invention, the tilt angle θ 3  is in a range from about 30 degree to about 60 degree to form an initial protection layer  406 , and an inner side of the concave portion  405  may be starting point for coating of the initial protection layer  406 . Here, the coating source  430  is a needle injection. In another exemplary embodiment of the present invention, the coating source  431  is a jet spray as shown in  FIG. 4F , moreover, the coating source may also be a drum type coating (not shown). Material for the initial protection layer  406  according to the present invention may be selected from various themo-polymerizable resins, such as acrylic thermosetting resins, thermo-curable PU resins, or thermo-curable epoxy resins. Other materials may also be used to produce the initial protection layer  406  according to the present invention, as long as it has appropriate viscosity and hardness and can be affixed to the substrate  400 , and may be utilized in the coating process. The material of the present invention has a photocurable property, and a cured product thereof shows a high adhesive strength without being influenced by e.g. cutting water. Here, the process temperature may be controlled to insure sufficient viscosity for the material before curing of the initial protection layer  406 . Here, resin hardness of the material for the initial protection layer  406  may be durometer hardness of A80 to A100. 
         [0053]    The  FIG. 4G  showed a completed cover lens strengthened by the method of the present invention. A cured protection layer  406 ′ eventually formed to cover the concave portion  405 , the etched upper chamfer surface  404 ′, and the chamfered side surface  403 ′ without covering the lower chamfer surface  407  (step S 36 ). Shape of the cured protection layer  406 ′ shaped in accordance with viscosity and hardness of material used for the protection layer  106 , temperature, humidity, and surface tension during processes for forming the cured protection layer  406 ′. An edge between the lower chamfer surface  407  and the chamfered side surface  403 ′ may also provide surface tension during the forming of the cured protection layer  406 ′. The curing of the initial protection layer  406  may include hardening by heat or ultraviolet light. Definition of first thickness T 1 , second thickness T 2 , and the third thickness T 3  are similar to the definition in  FIG. 2 , where the upper chamfer surface  104  corresponds to the etched upper chamfer surface  404 ′, the side surface  103  corresponds to the chamfered side surface  403 ′, and the outer periphery  108  of the protection layer  106  corresponds to an outer periphery  408  of the cured protection layer, as shown in  FIG. 2  and  FIG. 4G . The first thickness T 1  may be within a range of about 30 μm to about 40 μm. In another preferable embodiment of the present invention, the second thickness T 2  may be within a range of about 60 μm to about 80 μm. In a still another preferable embodiment, the third thickness T 3  may be within a range of about 100 μm to about 150 μm. 
         [0054]      FIG. 5  is a cross-sectional view from a side of a strengthened cover lens according to another exemplary embodiment of the present invention. A cover lens  5  includes an upper surface  501 , a lower surface  502 , a side surface  503 , an upper chamfer surface  504 , a concave portion  505 , a protection layer  506  with an outer periphery  508 , and a lower chamfer surface  507  are similar to the cover lens  1  in  FIG. 1 , therefore the detail description is omitted for conciseness. An electronic member  540  is disposed on the lower surface, the electronic member  540  may be any electronic members in the handheld electronic device and may include, but are not limited to communication devices; entertainment devices such as music players, game consoles, etc.; video camera means; and/or information terminal device (IT), such as laptop computers, etc., the cover lens  5  may serve as a cover glass, display screens, touch screens or glass with black matrix and back light modules utilized in liquid crystal display (LCD), light-emitting diode (LED), and organic light-emitting diode (OLED) display under thereof, and may be suitable for various type touch glass such as one glass sensor (OGS), cover glass-film, or glass-glass structures. 
         [0055]    In some embodiments, the strengthened cover lens according to the present invention has a value of B10 above 550 MPa, based on four point horizontal bend testing (4 pb). To create real-environment to test strength of the edge of the strengthened cover lens, the strengthened cover lens is fixed slantly at 45 degree, be pressed with 250 gr, and be scratched 10 mm by sand paper with roughness of #320, while using a computer numerical control (CNC) machine coupled to a jig. The processed samples of cover lens is placed between four point bending testing device, and be pressed with speed 5-10 mm/min. Here, the testing data comprising applied pressure and corresponding testing numbers is statistically analyzed by Weibull Distribution to get a value of B10, where the value of B10 means a testing pressure with 10% samples will break among a batch of testing samples. The obtained value of B10 of the strengthened cover lens samples of the present invention are above 550 MPa. Moreover, the strengthened cover lens also passes drop test and pendulum impact test. Samples of the strengthened cover lens of the present invention are safe from vertical free drop of 6 gr steel ball, and after pendulum impact of 168 gr steel cylinder stroke at 90 degree, only the protection layer made of polymer was torn. 
         [0056]    In accordance with aforementioned description, the present invention provides a strengthened cover lens and a method for strengthening a cover lens solve the problems concerning that conventional side-coated glass is broken under 300 MPa due to stress caused by cracks and defects created during processing of glass substrates. The method for strengthening a cover glass also provide a cover lens with a specific profile for side surface to ensure the shape of the protection layer is firmly served as a buffer on the side of the cover lens. 
         [0057]    Obviously, the present invention has made a breakthrough and definitely accomplished the desired improved effect which is not easily to think of by a skilled person in the art; moreover, the present invention has not been published prior to the file of the patent application, and the inventiveness, practicability thereof both conform with the patentability, and the patent application is hereby provided in accordance with the regulations. 
         [0058]    While the means of specific embodiments in present invention has been described by reference drawings, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims. The modifications and variations should in a range limited by the specification of the present invention.