Variable Thickness Face Plate for a Golf Club Head

This is a continuation of U.S. patent application Ser. No. 18/392,439, filed on Dec. 21, 2023, which is a continuation of U.S. patent application Ser. No. 17/087,462, filed on Nov. 2, 2020, which issued as U.S. Pat. No. 11,850,479 on Dec. 26, 2023, which claims the benefit of U.S. Provisional Patent Application No. 62/928,986, filed on Oct. 31, 2019 and is a continuation-in-part of U.S. patent application Ser. No. 15/973,386, filed on May 7, 2018, which issued as U.S. Pat. No. 11,161,019 on Nov. 2, 2021, which claims the benefit of U.S. Provisional Patent Appl. No. 62/608,363, filed on Dec. 20, 2017 and U.S. Provisional Patent Appl. No. 62/502,482, filed on May 5, 2017, the contents of all of which are fully incorporated herein by reference.

Characteristic time (CT) of a golf club head is a measurement used by the United States Golf Association (USGA) to determine the “spring-like effect” of the face plate on a golf ball. A golf club head having a high CT has increased flexibility and transfers greater energy to a golf ball on impact, compared to a golf club head having a low CT. However, the USGA limits the CT of the face plate of a golf club head.

Face plates or striking surfaces of hollow body style golf club heads generally have structural constraints creating regions of high CT towards the upper, toe end of the face plate, and regions of low CT towards the low and heel end of the face plate. Examples of structural constraints that affect the CT can include the stiffness of the hosel, or the weldline created while coupling the face plate to the club head body. The regions of high CT are generally located further away from structural constraints, while the regions of low CT are generally located in a closer proximity to structural constraints. Regions of high CT can generally be referred to as regions having “inherently high CT,” and regions of low CT can generally be referred to as regions having “inherently low CT.”

As discussed above, generally regions of inherently high CT exist towards in region extending from the center of the face plate towards the upper toe end of the face plate. Further, regions of inherently low CT exist around the perimeter of the face plate along with a region extending from the geometric center point towards the lower heel end of the club head. Discrepancies in the CT across the face plate can result in inconsistent ball flight characteristics imparted on the ball after impact.

Golf club manufacturers must ensure that all regions on the face plate, including regions having inherently high CT values, remain below the USGA limit. Typically, to ensure the highest CT regions remain at or below the USGA limit, manufacturers increase the thickness of the face plate. However, the thicker face plate also decreases the CT in the regions on the face plate having an inherently low CT. As such, these regions having inherently low CT are decreased further and have a CT well below the USGA limit. The result is a club head having large variation in CT values across the face plate surface, resulting in an inconsistent and/or lower performing club head. Accordingly, there is a need in the art for a golf club head having improved flexibility and consistency, while remaining within USGA conformance limits on characteristic time.

Other aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.

For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the present disclosure. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present disclosure. The same reference numerals in different figures denote the same elements.

Described herein is a hollow body golf club head comprising a face plate having a variable thickness to normalize characteristic time (CT) for different impact locations across the face. In many embodiments, the variable thickness face plate comprises a central region, a transition region, and a peripheral region. The thickened region can comprise an oval, ellipse, or ovoid shape, and can be symmetric about a major axis extending along the length of the thickened region. The thickened region can extend over the geometric center of the face plate and can be positioned such that the major axis is angled or tilted with respect to the ground plane, thereby defining an angled variable face thickness or angled VFT.

The club heads described herein address regions of inherently high and low CT, as described above, by increasing face plate thickness in regions of having inherently high CT to lower the regional CT value, while reducing the face plate thickness in regions having inherently low CT to raise the regional CT value. Accordingly, the club heads described herein have a more consistent and greater overall CT of the face plate, compared to similar club heads devoid of the angled VFT described herein, while remaining within USGA conformance guidelines.

The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “include,” and “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus.

The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the apparatus, methods, and/or articles of manufacture described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.

Disclosed herein are exemplary embodiments of a hollow bodied golf club head having normalized characteristic time (CT). The golf club head having normalized CT includes a body and a face plate having a variable thickness profile or variable face thickness (VFT).

The body comprises a crown, a sole, a toe end, a heel end and rear end defining an interior cavity. The body includes an opening into the interior cavity. The opening is configured to receive the face plate. The variable thickness profile of the face plate comprises a central region, a transition region and a peripheral region. In many embodiments, as described below, the central region is thickened, the peripheral region is thinned, and the transition region decreases in thickness from an outer perimeter of the central thickened region to the peripheral region.

In many embodiments, the variable thickness profile or variable face thickness is positioned at an angle relative to a ground plane, generating an angled variable thickness profile or angled VFT. Further, in many embodiments, the variable thickness profile comprises an oval shape positioned such that an area of maximum or increased thickness is greater near the crown and/or toe end than near the heel and/or sole.

The hollow body golf club head can be a driver, a fairway wood, a hybrid or a cross-over type club head. The club head can have a volume in the range of 75 cc to 500 cc. For example, the volume of the golf club head can be in the range of 75 cc to 150 cc, 200 cc to 300 cc, 250 cc to 350 cc, 400 cc to 440 cc, 430 cc to 450 cc, 440 cc to 460 cc, 450 cc to 470 cc, 460 cc to 480 cc, 470 cc to 490 cc, or 480 cc to 500 cc. In other embodiments, the volume of the golf club head can be 75 cc, 100 cc, 150 cc, 200 cc, 250 cc, 300 cc, 350 cc, 400 cc, 440 cc, 445 cc, 450 cc, 455 cc, 460 cc, 465 cc, 470 cc, 475 cc, 480 cc, 485 cc, 490 cc, 495 cc, or 500 cc.

Further, the loft of the club head can be in the range of 5 degrees to 40 degrees. For example, the golf club head can have a loft of 5 degrees to 15 degrees, 10 degrees to 20 degrees, 15 degrees to 25 degrees, 20 degrees to 30 degrees, 25 degrees to 35 degrees, or 30 degrees to 40 degrees. In other embodiments, the golf club head 10 can have a loft of 5 degrees, 6 degrees, 7 degrees, 8 degrees, 9 degrees, 10 degrees, 11 degrees, 12, degrees, 13 degrees, 14 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, or 40 degrees.

The club head may further include a hoselconfigured to receive a first end of a shaft (not shown). The shaft may be secured to the golf club head by an adhesive bonding process (e.g., epoxy) and/or other suitable bonding processes (e.g., mechanical bonding, soldering, welding, and/or brazing). Further, a grip (not shown) may be secured to a second end of the shaft (not shown) to form a usable golf club.

Referring to, an exemplary embodiment of a golf club headhaving normalized CT is illustrated. The club headcomprises a bodyand a face plate or strike facehaving a variable thickness profile or variable face thickness. The face plateand the bodytogether form the club headhaving a hollow interior or void or inner cavity.

Referring to, the bodyof the club headis displayed. The bodycomprises a crown portion, a sole portion, a toe portion, a heel portion, and a rear portiondefining an inner cavity. In the illustrated embodiment, the bodyincludes an openingpositioned on a forward most portion of the club head. The openingis configured to receive the face plate. In some embodiments, the opening can be positioned on a front end of the club head and can be configured to receive an insert style face plate. In other embodiments, the opening can be positioned along the crown portion and/or sole portion of the club head and can be configured to receive a cup-face style face plate or a face plate having a return portion or cup-like geometry.

The club head bodycan comprise a strong, light weight material. For example, the club head bodycan be formed from stainless steel, titanium, aluminum, steel alloys (e.g. 455 steel, 475 steel, 431 steel, 17-4 stainless steel, maraging steel), titanium alloys (e.g. Ti-7-4, Ti-8-1-1, or Ti-6-4), composite materials such as, for example, plastic polymers, thermoset polymers, thermoplastic polymers, co-polymers, carbon fibers, fiberglass fibers, metal fibers, or any combination thereof.

Referring to, the face plateof the club headis displayed. The face platecomprises a top or top portion, a bottom or bottom portion, toe or toe portion, a heel or heel portion, a front surface, a rear surface, and a variable face thickness (VFT) or variable thickness profile. The face platecan be a planar surface or the face platecan have a slight bulge and/or roll curvature.

Referring to, a side cross-sectional view taken along the line-ofis shown. The face platefurther includes a loft angle, measured as the angle between a loft plane and a vertical plane. The loft plane extends through, and is tangent to, a geometric centerof the face plate. The vertical planeextends through the geometric centerof the face plate, perpendicular to the ground plane when the club headis held in a neutral or address position.

Further referring to, the geometric centerof the face platecan be located at a geometric midpoint of the face plate. In the same or other examples, the geometric centeralso can be centered with respect to an engineered impact zone, which can be defined by a region of grooves of the face plate. As another approach, the geometric centerof the face platecan be located in accordance with the definition of a golf governing body such as the United States Golf Association (USGA). For example, geometric centerof the face platecan be determined in accordance with Section 6.1 of the USGA's Procedure for Measuring the Flexibility of a Golf Clubhead (USGA-TPX3004, Rev. 1.0.0,May 1. 2008) (available at http://www.usga.org/equipment/testing/protocols/Procedure-For-Measuring-The-Flexibility-Of-A-Golf-Club-Head/) (the “Flexibility Procedure”)

The geometric centerof the face platedefines an origin of a coordinate system having an x-axis or horizontal axis, and a y-axis or vertical axis. The x-axisextends horizontally through the geometric centerof the face platefrom near the heel portionto near the toe portionof the club headin a direction parallel to a ground plane when the club headis at an address position. The y-axisextends vertically through the geometric centerof the face platefrom near the crown portionto near the sole portionof the club headin a direction perpendicular to the x-axis and to the ground plane when the club headis at an address position.

In some embodiments, the face plate or strike facemay be formed separately from the bodyand subsequently coupled to the bodyto form the hollow body club head. In these or other embodiments, the face plate or strike facemay be coupled to the bodyvia a weld bond, a brazed bond, a co-molded bond, an adhesive bond, a mechanical fastener, or any other suitable attachment method.

The face platecan comprise a strong, light weight material. For example, the club head bodycan be formed from stainless steel, titanium, aluminum, steel alloys (e.g. 455 steel, 475 steel, 431 steel, 17-4 stainless steel, maraging steel), titanium alloys (e.g. Ti-7-4, Ti-8-1-1, or Ti-6-4), composite materials such as, for example, plastic polymers, thermoset polymers, thermoplastic polymers, co-polymers, carbon fibers, fiberglass fibers, metal fibers, or any combination thereof. The face platecan comprise the same material as, or a different material than the body.

Referring to, the face plateof the club headcomprises a thickness T measured as the distance between a front surfaceand a rear surface. The thickness T of the face platevaries at different locations across defining a variable face thickness (VFT) or variable thickness profile. The variable thickness profileof the face platecomprises a central region, a transition region, and a peripheral regionformed by the variation in thickness of the face plate.

Referring to, the central regionextends over or is positioned on or near the geometric centerof the face plate, such that the geometric centerof the face plateis located in the central region. The central regioncomprises a maximum thickness of the face plate. In many embodiments, the thickness of the central regionis substantially constant. Further, the peripheral regionis positioned around the perimeter of the face plate and comprises a minimum thickness of the face plate. In many embodiments, the thickness of the peripheral regionis substantially constant. The thickness of the face platein the central regionis greater than the thickness of the face platein the peripheral region. Further, in many embodiments, the transition regionincludes a varying thickness that creates a smooth transition between the central regionand the peripheral region. In the illustrated embodiment, the thickness of the face platein the transition regiontapers between the maximum face plate thickness in the central regionand the minimum face plate thickness in the peripheral region. In other embodiments, the thickness of the face platein the transition region can vary according to any profile including straight and/or curved geometries.

i. Central Region

In the illustrated embodiment, the central regionof the variable thickness profilecomprises an ellipse, oval (or ovoid), or egg-like shape. The central regionis generally oblong and extends from a portion of the face platenear the bottomand heelto a portion of the face platenear the toeand top. In other embodiments, the central regioncan comprise any other shape having a single axis of symmetry. The shape of the central regiondefines a major axisextending in a general heelto toedirection and a minor axisextending generally in a topto bottomdirection. The major axisand the minor axisintersect at a center of the central region. The major axisextends along a length of the central region, and the minor axisextends along a maximum width of the central region.

In the illustrated embodiment of, the central regionof the variable thickness profileis symmetric about a single axis. In the illustrated embodiment, the central regionis symmetric about the major axis, and is not symmetric about the minor axis. Accordingly, the width of the central regionvaries along the length of the central regionfrom the heelto the toe. In the illustrated embodiment, the width of the central regionis greater near the heelthan near the toe, when measured at locations equidistant from the minor axis. By way of non-limiting example, the width of the central region measured 0.25 inch from the minor axistoward the heelis greater than the width of the central regionmeasured 0.25 inch from the minor axistoward the toe.

In the illustrated embodiment of, the center of the central regioncorresponds to the geometric centerof the face plate. In other embodiments, the center of the central regioncan be in a different location than the geometric centerof the face plate. In the illustrated embodiment, the central regionis symmetric about an axis that passes through the geometric center. In other embodiments, the central regioncan be asymmetrical over any axis passing through the geometric centerof the face plate.

The central regioncomprises a first side or toe sideand a second side or heel side. The first sideand second sideof the central regionare separated by the minor axis. The first side is positioned between the minor axisand the toe portion, and the second side is positioned between the minor axisand the heel portion. The first sidecan be formed by a portion of (or by half of) a first ellipse, and the second sideof the central regioncan be formed by a portion of (or by half of) a second ellipse. The length of the first ellipse, measured along the major axis, is greater than the length of the second ellipse.

In many embodiments, the central regionof the variable thickness profileof the club headcomprises a ratio measured as the surface area of the first sideto the surface area of the second sidebetween 1.2 and 2.0. In some embodiments, the ratio of the surface area of the first sideto the surface area of the second sideof the central regionis greater than 1.0, greater than 1.1, greater than 1.2, greater than 1.3, greater than 1.4, greater than 1.5 greater than 1.6, greater than 1.7, greater than 1.8, greater than 1.9, greater than 2.0, or greater than 2.5. For example, in some embodiments, the ratio of the surface area of the first sideto the surface area of the second sideof the central regioncan be between 1.0 and 2.0, between 1.1 and 2.0, between 1.2 and 2.0, between 1.3 and 2.0, between 1.4 and 2.0, or between 1.5 and 2.5.

In the illustrated embodiment, the central regioncomprises a toe-side length TL, a heel-side length HL, a top-side length PL, and a bottom-side length BL. The toe-side length TL is measured along the major axisfrom the center of the central regiontoward the toe. The heel-side length HL is measured along the major axisfrom the center of the central regiontoward the heel. The top-side length PL is measured along the minor axisfrom the center of the central regiontoward the top. The bottom-side length BL is measured along the minor axisfrom the center of the central regiontoward the bottom.

In the illustrated embodiment, the top-side length PL and the bottom side length BL are 0.285 inches. In other embodiments, the top-side length PL and/or the bottom side length BL can be between 0.05 and 1.0 inches. For example, in some embodiments, the top-side length PL and/or the bottom side length BL can be between 0.05 and 0.25, 0.15 and 0.35, 0.25 and 0.45, 0.35 and 0.55, 0.45 and 0.65, 0.55 and 0.75, 0.65 and 0.85, or 0.75 and 0.1 inches. In the illustrated embodiment, the top-side length PL and the bottom-side length BL are the same. In other embodiments, the top-side length PL can be greater than the bottom-side length BL, or the bottom-side length BL can be greater than the top-side length PL.

In the illustrated embodiment, the toe-side length TL is 0.546 inches, and the heel-side length HL is 0.312 inches. In other embodiments, the toe-side length TL can range from 0.2 to 1.5 inches. For example, in some embodiments, the toe-side length TL can range from 0.2 to 0.4, 0.3 to 0.5, 0.4 to 0.6, 0.5 to 0.7, 0.6 to 0.8, 0.7 to 0.9, 0.8 to 1.0, 0.9 to 1.1, 1.0 to 1.2, 1.1 to 1.3, 1.2 to 1.4, or 1.3 to 1.5 inches. Further, in other embodiments, the heel-side length HL can range from 0.1 to 0.7 inches. For example, in some embodiments, the heel-side length HL can range from 0.1 to 0.3, 0.2 to 0.4, 0.3 to 0.5, 0.4 to 0.6, or 0.5 to 0.7 inches. The toe-side length is greater than the heel-side length. The difference in between the toe-side length TL and the heel-side length HL generates or forms the ovoid, ellipsoidal, or egg-shaped contour displayed inand enables normalization of CT across the face plate.

In the illustrated embodiment, the central regionhas a thickness of 0.135. In other embodiments, the thickness of the central regioncan vary from 0.070 to 0.25 inches. For example, in some embodiments, the thickness of the central regioncan be from 0.07 to 0.1, 0.09 to 0.1, 0.095 to 0.105, 0.1 to 0.12, 0.105 to 0.115, 0.11 to 0.12, 0.115 to 0.125, 0.12 to 0.13, 0.125 to 0.135, 0.13 to 0.14, 0.135 to 0.145, 0.14 to 0.15, 0.145 to 0.155, 0.15 to 0.17, 0.16 to 0.18, 0.17 to 0.2, 0.19 to 0.22, or 0.21 to 0.25 inches. Further, in the illustrated embodiment, the central regioncomprises 6% of the total surface area of the face plate. In other embodiments, the central regioncan comprise less than 5%, less than 10%, less than 15%, less than 20%, less than 25%, or less than 30% of the total surface area of the face plate. For example, the central regioncan comprise 2-10%, 5-10%, 2-15%, 5-15%, or 5-20% of the total surface area of the face plate.

In many embodiments, the central regionis disposed at an angle on the rear surfaceof the face plateof the club head. Specifically, the major axisof the central thickened regionis disposed at an angle with respect to the x-axis. The angle can be configured such that the first sideor long portion of the central regionextends from the geometric centerof the face platetowards the upper-toe portion of the face plate, wherein the regions of inherently high CT exist.

In the illustrated embodiment, the minor axisof the central regionforms an angle of 20 degrees with the y-axis. In other embodiments, the minor axisof the central regioncan form an angle of 2 to 60 degrees with the y-axis. For example, in some embodiments, the minor axisof the central regionand the y-axiscan create an angle between 2 to 20, 2 to 30, 5 to 40, 10 to 50, or 15 to 60 degrees. In other embodiments, the minor axisof the central thickened regioncan create an angle of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 degrees with the y-axis.

Further, in the illustrated embodiment, the major axisof the central regionforms an angle ofdegrees with the x-axis. In general, the angle formed between the major axis of the central regionand the x-axisis the same as the angle formed between the minor axisof the central regionand the y-axis. For example, the angle formed between the major axisof the central regionand the x-axiscan vary from 0 to 60 degrees. In some embodiments, the angle formed between the major axisof the central regionand the x-axiscan vary from 2 to 20, 2 to 30, 5 to 40, 10 to 50, or 15 to 60 degrees. In other embodiments, the major axisof the central regioncan create an angle of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 degrees with the x-axis. By disposing the central thickened regionon an angle it further allows the elongated portion of the egg-shape to extend towards the upper-toe portion if the face platewherein high CT values exist.

Further, illustrated in, the central regioncan be shifted from the y-axis, towards the toe portionof the golf club head. In most embodiments, the central regionis shifted toward the toe portionby at least 0.05 inches, by at least 0.10 inches, by at least 0.15 inches, by at least 0.20 inches, by at least 0.25 inches, or by at least 0.30 inches. In some embodiments, the central region 50 is shifted toward the toe portion 33 by 0.05 inches, 0.06 inches, 0.07 inches, 0.08 inches, 0.09 inches, 0.10 inches, 0.11 inches, 0.12 inches, 0.13 inches, 0.14 inches, 0.15 inches, 0.16 inches, 0.17 inches, 0.18 inches, 0.19 inches, 0.20 inches, 0.21 inches, 0.22 inches, 0.23 inches, 0.24 inches, 0.25 inches, 0.26 inches, 0.27 inches, 0.28 inches, 0.29 inches, or 0.30 inches.

ii. Transition Region

Referring to, the transition regionof the variable face thicknessextends from the perimeter of the central thickened regionto the peripheral region. In the illustrated embodiment, the transition regiongradually tapers from a thickest portion near the perimeter of central thickened regiontowards a thinnest region near or adjacent to the peripheral region. The thickest region of the transition regioncan be equal to or slightly less than the thickness of the central thickened region, while the thinnest region of the transition regioncan be equal to, or slightly greater than the peripheral region.

In many embodiments, the transition regioncan comprise a shape similar to or corresponding to the shape of the central region. In the illustrated embodiment, the transition regionextends a constant or fixed distance of 0.45 inches from the perimeter of the central thickened regionto the peripheral region. In other embodiments, the transition region can extend from 0.15 to 0.75 inches from the perimeter of the central thickened regionto the peripheral region. For example, in some embodiments, the transition regioncan extend between 0.15 to 0.35, 0.25 to 0.45, 0.35 to 0.55, 0.45 to 0.65, or 0.55 to 0.75 inches from the perimeter of the central thickened regionto the peripheral region. In yet another embodiment, the distance the transition regionextends from the perimeter of the central thickened regioncan vary. For example, the length of the transition regionextending towards the top portionof the face platecan be greater or less than the length of the transition regionextending towards the bottom portionof the face plate. In other embodiments, the length of the transition regionextending in any direction from the central thickened regioncan be greater than, less than or the same as the length of the transition regionextending in any other direction from the central thickened region.

Further, in the illustrated embodiment, the transition regioncomprises 27% of the total surface area of the face plate. In other embodiments, the transition regioncan comprise between 10% and 70% of the total surface area of the face plate. For example, in some embodiments, the transition regioncan comprise between 10% to 30%, 20% to 40%, 30% to 50%, 40% to 60%, or 50% to 70% of the total surface area of the face plate.

iii. Peripheral Region

Referring again to, the peripheral regionof the variable thickness profileextends from the perimeter of the transition regionto the perimeter of the face plate. In the illustrated embodiment, the thickness of the peripheral regionis 0.85 inches. In other embodiments, the thickness of the peripheral regioncan be less than 0.15 inches. For example, in some embodiments, the peripheral regioncan be less than 0.15 inches, less than 0.1 inches, less than 0.09 inches, less than 0.08 inches, less than 0.07 inches, less than 0.06 inches, less than 0.05 inches, or less than 0.04 inches.

Further, in the illustrated embodiment, the peripheral regioncomprises 67% of the total surface area of the face plate. In other embodiments, the peripheral regioncan comprise 30% to 90% of the total surface area of the face plate. For example, in some embodiments, the peripheral regioncan comprise between 30% to 50%, 40% to 60%, 50% to 70%, 60% to 80%, or 70% to 90% of the total surface area of the face plate.