CA3009511A1 - Contour sheet and method of making thereof - Google Patents

Abstract

A contour sheet comprising a mattress cover surface and a plurality of side surfaces, wherein at least a portion of the side surfaces is configured to be resilient and extendible along a depth of a mattress such that said contour sheet is releasably secured to the mattress, wherein one resilient member is sewn along at least one edge of an opening with at least two edges of a generally polygon shaped cutout at one or more comers of the sheet, said one resilient member configured to be extendible along the depth of the mattress, said one resilient member being encased in a protective sleeve or channel, and adjacent edges of said opening are sewn together. Having at least a portion of the side surfaces resilient ensures that the contour sheet is releasably secured in position on the mattress.

Description

CONTOUR SHEETS AND METHODS OF MAKING THEREOF
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This non-provisional patent application claims priority of U.S. Provisional Patent Application No. 62/273,483 titled "Contour Sheets and Methods of Making Thereof' filed on December 31, 2015, the entire contents of which is incorporated herein by reference.
FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to the field of bedding, and particularly to contour sheets or fitted sheets that may be used to cover a mattress.
BACKGROUND

[0003] Bedding sets typically include bed skirts, contour sheets or fitted sheets that cover the mattress, top sheets or flat sheets, blankets or duvets and pillow shams among other items. Contour sheets, which are also known as fitted sheets in some countries, not only provide comfort, but also provide the advantage of the contour sheets being washed regularly instead of frequently washing mattresses, thereby providing equivalent effect of cleanliness and hygiene, which in turn increases user convenience and reduces associated costs and resources on a recurring basis, Additionally, these items also provide an appealing bed presentation especially with apt color combinations and designs. However, an important aspect from the point of view of aesthetic appeal, comfort and safety is how well the bedding items are laid and avert accidents due to overhanging portions that may cause tripping, loose contour sheets that come off from frequent use and fail to serve the intended purpose.

[0004]
Mattresses are generally available in standard sizes such as King, Queen, Twin, Full and the like. A lot of research has been put into modifying mattress quality to meet consumer demand for improved sleep experiences. Accordingly, the market has been flooded with different types of mattresses that have different types of fillers and thicknesses and aim to provide individualized comfort to consumers. It is noteworthy that the size of the mattress continues to be standard but these innovations have resulted in mattresses with varying depths. Likewise, sofas, couches, love seats and tuffets can have standard sized cushions but with varying depth depending on consumer preferences directed at firmness, softness, bounce, and the like. A contour sheet or fitted sheet is a critical and basic item in bedding sets that is laid over the mattress and is intended to snugly fit the mattress.
Contour sheets can

5 also find application in seat cushions and tuffets. With varying depths of mattresses and seat cushions available in the market today, there is a need to ensure that contour sheets are standardized for a particular size and are yet able to cater to the varying depths of mattresses or cushions available for each size.
[0005] Contour sheets are required to be durable enough to support weight of the person(s) sleeping on the mattress or sitting on the cushion. Sleeping or sitting entails a lot of movement, tossing or turning that tend to ruffle the intended fitted look and feel of contour sheets. Loosening can result in contour sheets coming off the mattress and entangle with the top sheet causing discomfort and hazard. Elasticity provided to secure contour sheets around mattresses and cushions also become un-effective over repeated wash and use.
SUMMARY

[0006] The present invention in its various embodiments addresses the above and other possible needs relating to the field of contour sheets or fitted sheets.

[0007] Aspects of present disclosure relate to contour sheets, which are also known as fitted sheets in some countries, and methods of making thereof. In accordance with an aspect of the present disclosure, a contour sheet having a top surface and a plurality of side surfaces can be characterized by at least one of the side surfaces being configured to be resilient and extendible in a vertical direction, along the depth of a mattress on which the contour sheet may be spread. Having at least a portion of the side surfaces resilient ensures that the contour sheet is releasably secured in position on the mattress.

[0008] In accordance with an embodiment, at least a portion of the side surfaces can be provided with at least one resilient member that can be configured to be extendible along the depth of the mattress.

[0009] In accordance with an embodiment, the at least one resilient member can be sandwiched between one or more layers of fabric to evade exposure of the resilient members to external factors such as high temperature during laundry cycles and increase durability and effectiveness of the same.

[00010] In accordance with an embodiment, at least a portion of the mattress side surfaces can be provided with sets of resilient members, each of the sets can include a plurality of resilient members configured to be extendible in a vertical direction, along the depth of a mattress on which the contour sheet may be spread.

[00011] In accordance with an embodiment, each of the plurality of resilient members constituting the sets of resilient members can be further sandwiched between one or more layers of fabric for minimizing exposure to external factors such as high temperature that can be detrimental to the durability and effectiveness of the resilient members.

[00012] In accordance with an aspect, a method of making a contour sheet having a top surface and a plurality of side surfaces can include the step of coupling at least a portion of the side surfaces with at least one resilient member that can be configured to be extendible in a vertical direction, along the depth of a mattress on which the contour sheet may be spread.

[00013] In accordance with an embodiment, the step of coupling can include the step of sewing the at least one resilient member sandwiched between one or more layers of fabric.

[00014] In accordance with another embodiment, the method of making a contour sheet can further comprise cutting a generally polygonal shaped cutout at the corners of the fabric to form an opening with at least two edges, coupling at least one resilient member along at least one edge of the opening and sewing adjacent edges of the opening together.

[00015] In accordance with an embodiment, the step of coupling can include the step of sewing a fabric attachment that generally conforms to the shape of the opening; the fabric attachment having at least one resilient member along at least one edge of the fabric attachment.

[00016] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
BRIEF DESCRIPTION OF THE DRAWINGS

[00017] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[00018] FIG. 1 illustrates a schematic representation of an exemplary contour sheet provided with a plurality of resilient members disposed along mattress side surfaces in accordance with an embodiment of the present disclosure.

[00019] FIG. 2A
illustrates a schematic representation of an exemplary contour sheet with polygonal shaped cutouts forming openings at the corners with at least two edges before sewing in accordance with an embodiment of the present disclosure.

[00020] FIG. 2B
illustrates a schematic representation of an exemplary contour sheet with polygonal shaped cutouts forming openings at the corners with at least two edges before sewing in accordance with an embodiment of the present disclosure.

[00021] In the Figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
DETAILED DESCRIPTION

[00022] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

[00023] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.

[00024] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. "such as") provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[00025] All publications herein, if incorporated, are by reference to the same extent as if each individual publication or patent applications were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

[00026] Various terms as used herein are shown below. To the extent a term used in the instant application is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.

[00027] The expression "mattress" referred to in the instant application refers to a fabric case filled with fillers including but not limited to one or more combinations of cotton, hair, feathers, foam, rubber, springs, and the like. All embodiments claimed and described herein with regards to "mattress" are understood to include "mattress" used as a bed by itself, on a bedstead, water beds, air beds, "seat cushions" used on a sofa, couch, love seat, chair and the like and tuffets.

[00028] The expression "contour sheets" referred to in the instant application refers to sheets configured to fit snugly over mattresses, as defined herein above, of different depths.
The expression "contour sheets" may also be interpreted to include "fitted sheets" or "bottom sheets". Contour sheets may also include one or more layers of fabric, stiffeners, resilient material and the like in at least some portions of the sheets.

[00029] The expression "resilient" referred to in the instant application refers to a property of a material that enables it to return to its original shape after being pulled or stretched.

[00030] The expression "resilient member" referred to in the instant application may include elastomeric materials that are inherently resilient by nature, such as elastic and also materials that can be pulled or tugged and released by means of ropes, cords, drawstrings configured therein to achieve desired tensioning or release effect. The expression "resilient member" may also include fabric configured with resilience by techniques such as but not limited to smocking and shirring. "Resilient member" in the instant application can take any form including but not limited to bands, tapes, strips, threads, and the like.

[00031] The expressions "sew" and "stitch" may be used interchangeably to imply fastening or joining by stitching or other forms of bonding, as known in the art and may be a manual process or may involve use of machines.

[00032]
Embodiments of the present disclosure relate to contour sheets and methods of making thereof. For ease of explanation, the embodiments shall now be explained with reference to a non-limiting exemplary application to mattresses used in beddings, although the embodiments can be applied to cushions as per definition of the expression "mattress" in the context of the instant application. Contour sheets fit mattresses snugly and facilitate good bed presentation. Contour sheets are subjected to a lot of stress because of it nature of being fitted around the mattress with continuous vertical pressure due to moving weight. Contour sheets must not only support its own weight in stretched condition, but also withstand external force that may be applied by weight of the person(s) lying or sitting on or tossing and turning on the mattress. The present disclosure aims to provide durable and effective contour sheets that can address these requirements and at the same time cater to mattresses of different depths.

[00033] FIG. 1 illustrates a schematic representation of exemplary contour sheet 100 having a top surface 102 and a plurality of side surfaces 104. To facilitate flexibility and ensure that contour sheets cater to varying depths of mattresses, at least a portion of the side surfaces 104 can be configured to be resilient and extendible in a vertical direction along the depth of the mattress. Resilient mattress side surfaces 104 ensure that contour sheet 100 can be releasably secured in position on the mattress.

[00034] The present disclosure provides various embodiments to achieve resilience and meet the intended objects of the disclosure. In an embodiment, at least a portion of the side surfaces 104 can be configured to be resilient. For instance, at least a portion of the side surfaces 104 can be made of stretchable material such as Lycra or Spandex and the like.
In an embodiment, corners 108 of the side surfaces 104 that conform to the four comers of the mattress on which the contour sheet may be spread can be made of such resilient material.
Alternatively, spaced apart portions of the side surfaces 104 can be made of such resilient material. In another embodiment, the side surfaces 104 can be monolithic and made entirely of such resilient material.

[00035] In an embodiment, at least a portion of the side surfaces can be provided with at least one resilient member configured to be extendible along the depth of the mattress or at an angle relative to the depth of the mattress. In a non-limiting example, the at least one resilient member may be attached in a vertical direction along the depth of the mattress or at an angle relative to the vertical direction. In accordance with the illustrated embodiment of FIG. 1, the side surfaces 104 can be provided with a plurality of resilient members 106.
The resilient members 106 can be any elastomeric or elastic material and can take any form including but not limited to bands, strips, tapes, threads and the like. Alternatively, in accordance with the present disclosure, the at least one resilient member 106 can also be in the form of drawstrings configured to be pulled or tugged and locked by any means known in the art including cord lock or cord toggle to restrain the drawstring and create the desired tensioning or release effect in the drawstrings. In accordance with another embodiment, the resilient member can be fabric configured with resilience using techniques such as but not limited to smocking and shirring.

[00036] In accordance with an embodiment, contour sheets can also be configured with at least one resilient member sandwiched between one or more layers of fabric to prevent direct exposure of the resilient members to heat during laundry cycles and increase longevity thereof. In an embodiment, the at least one resilient member can be configured along corners of side surfaces that conform with corners of the mattress. Alternatively, resilient members 106 can be configured in a spaced apart manner along the side surfaces, as illustrated in Fig.
1, for example.

[00037] Repeated use involving removal, washing and replacement of contour sheets cause the resilient members to lose their elastic properties. This can prove detrimental since the contour sheets can be inadvertently removed during use and can get entangled in the bedstead or with the top sheet and cause discomfort to the person(s) using the mattress. In accordance with an embodiment, at least a portion of the side surfaces of the contour sheet can be provided with a set of resilient members. Each set of resilient members can include a plurality of resilient members configured to be extendible along the depth of the mattress or at an angle relative thereto. In another embodiment, each of the plurality of resilient members can be sandwiched between one or more layers of fabric to ensure minimum exposure to heat during various processes the contour sheets may be subjected to. Providing a plurality of layers of resilient members also ensures that in the event of failure of the outermost resilient member(s) in a set due to excessive wear, at least the innermost resilient member(s) can provide the intended resilience. Also, providing a plurality of layers of resilient members helps in distribution of load which otherwise would have been concentrated on the single resilient members thereby subjecting the same to excessive wear and reducing its longevity.

[00038] In an embodiment, sets of resilient members 106 can be configured either at the corners 108 that conform with corners of the mattress and/or in a spaced apart manner along the mattress side surfaces.

[00039] In an exemplary embodiment of the present disclosure, a contour sheet having one or more resilient members of approximately 9 inches un-extended length can provide an extended length of at least 16 inches or more depending on the type of resilient member and its application. Accordingly, the exemplary contour sheet can cater to mattresses having depth ranging from 9 inches to 16 inches or more. In accordance with the present disclosure, the resilient members can be configured to provide an elongation ratio of the un-extended to extended length of the side surfaces along the depth of the mattress in the order of about 1:3 or more.

[00040] One example embodiment is a method of making a contour sheet including the step of coupling at least a portion of at least one of the side surfaces with at least one resilient member that can be configured to be extendible in a vertical direction, along the depth of the mattress. In an embodiment, the step of coupling can include the step of sewing at least one resilient member sandwiched between one or more layers of fabric. In another embodiment, the step of coupling can include the step of sewing at least one resilient member either at the corners that conform with the comers of the mattress or in a spaced apart manner along the mattress side surfaces.

[00041] In an example embodiment, the method of the present disclosure can include steps of cutting a generally polygonal shaped cutouts at the comers to form openings with at least two edges, coupling the at least one resilient member along at least one edge of the opening and sewing adjacent edges of the opening together.

[00042] In an embodiment, the step of coupling can include the step of sewing the at least one resilient member along at least one edge of the opening. In another embodiment, the at least one resilient member can be encased in a protective sleeve or channel. In an embodiment, the protective sleeve or channel can be a stiffener. In an embodiment, the step of coupling at least one resilient member along at least one edge of the opening can include the step of sewing at least one resilient member sandwiched between one or more layers of fabric.

[00043] In another embodiment, the at least one resilient member can be disposed proximate another resilient member such that each of the resilient members are sandwiched between one or more layers of fabric to form at least a set of resilient members to improve durability and maintain effectiveness of the resilient members.

[00044] FIGS. 2A
and 2B illustrate schematic representations of exemplary contour sheets 200A and 200B, respectively, with openings at the corners before sewing in accordance with an embodiment of the present disclosure. The illustrated phantom lines serve to indicate corners of contour sheets prior to cutting out of the openings.
FIG. 2A illustrates contour sheet 200A having openings with generally L-Shaped edges 202 whereas FIG. 2B
illustrates contour sheet 200B having openings with generally V-Shaped edges 204. The exemplary embodiment of FIG. 2A illustrates a resilient member 106 provided on one edge of each of the L-Shaped cut corners and then seams are created overlapping the resilient members 106 necessitating only a single seam at each corner. In an embodiment, the step of coupling at least one resilient member along at least one edge of the opening can include the step of sewing a fabric attachment that conforms generally to the shape of the opening wherein, the fabric attachment can be configured with at least one resilient member sewed along at least one edge of the fabric attachment. FIG. 2B illustrates such an embodiment wherein resilient members 106 are provided on two edges of the generally V-Shaped edges of triangular fabric attachment 206 that conforms generally with the V-shaped edges 204 of contour sheet 200B. Besides providing a better fit by use of two resilient members, the triangular shape does not easily deform and can balance the stretching and compressive forces that the contour sheet is subjected to by the weight of person(s) lying down sitting, tossing or turning on the mattress. The resilience provided by the resilient members ensures that the net force or stretch along the depth of the mattress is zero and the contour sheet does not fail at the corner seams. The contour sheets of the present disclosure maintain tautness of the sheet and flexibility to cater to varying depths of the mattress and thereby provide simple and inexpensive means to releasably secure contour sheets over the mattress.

[00045] Although example embodiments described herein illustrate the top surface 102 of the contour sheet 100 as covering the entire top surface of the mattress, the invention is not limited as such. In a non-limiting example, the top surface 102 may cover only a portion of the top surface of the mattress, and the resilient members 106 may be stretched in such instances to cover the entire side surfaces of the mattress.

[00046] Example embodiments disclosed provide contour sheets that make optimum use of resilient members to provide the desired flexibility for catering to varying depths of mattresses. Example embodiments also provide contour sheets that facilitate taut and stretched mattress cover surface for aesthetic bed presentation. Example embodiments also provide simple and cost effective contour sheets that are easy to manufacture, and more durable than the existing sheets.

[00047] In addition to the embodiments and examples shown, numerous variants are possible, which may be obvious to a person skilled in the art relating to the aspects of the invention. In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term "about." Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[00048] As used in the description herein and throughout the claims that follow, the meaning of "a," "an," and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of "in"
includes "in" and "on" unless the context clearly dictates otherwise.

[00049] The recitation of ranges of values, if used herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range.
Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. "such as") provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[00050]
Groupings of alternative elements or embodiments of the invention, if any, disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[00051] The terms "comprises," "comprising," "including," and "having," are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[00052] The use of the expression "at least" or "at least one" suggests the use of one or more elements, as the use may be in one of the embodiments to achieve one or more of the desired objects or results.

[00053] The aim of this specification is to describe the invention without limiting the invention to any one embodiment or specific collection of features. A person skilled in the relevant art may realize the variations from the specific embodiments that will nonetheless fall within the scope of the invention.

[00054] It may be appreciated that various other modifications and changes may be made to the embodiment described without departing from the spirit and scope of the invention.

Claims (25)

1. A method of making a contour sheet having a top surface and a plurality of side surfaces, said method comprising:
coupling at least a portion of one of the side surfaces with at least one resilient member configured to be extendible along a depth of a mattress.

2. The method of claim 1, wherein the step of coupling comprises the step of sewing said at least one resilient member between one or more layers of a fabric.

3. The method of claim 1, wherein the step of coupling comprises the step of sewing said at least one resilient member in a spaced apart manner along at least one of the side surfaces.

4. The method of claim 1, wherein the step of coupling comprises the step of sewing said at least one resilient member along corners that conform with corners of the mattress.

5. The method of claim 1, further comprising:
cutting a generally polygon shaped cutout at one or more corners of the sheet to form an opening with at least two edges;
(ii) coupling said at least one resilient member along at least one edge of said opening, said at least one resilient member configured to be extendible along the depth of the mattress; and (iii) sewing adjacent edges of said opening together.

6. The method of claim 5, wherein said opening has a generally L-shaped edge.

7. The method of claim 5, wherein said opening has a generally V-shaped edge.

8. The method of claim 5, wherein the step of coupling comprises the step of sewing said at least one resilient member along at least one edge of said opening.

9. The method of claim 5, wherein the step of coupling comprises the step of sewing said at least one resilient member along at least one edge of said opening, said at least one resilient member being encased in a protective sleeve or channel.

10. The method of claim 5, wherein the step of coupling comprises the step of sewing a fabric attachment conforming generally to the shape of said opening thereon, said fabric attachment having at least one resilient member sewed along at least one edge of said fabric attachment.

11. The method of claim 5, wherein the step of coupling comprises the step of sewing said at least one resilient member sandwiched between one or more layers of a fabric.

12. The method of claim 1, wherein said at least one resilient member is disposed proximate to at least one other said resilient member such that each of said resilient members are sandwiched between one or more layers of a fabric to form at least one set of resilient members.

13. A contour sheet comprising a mattress cover surface and a plurality of side surfaces, wherein at least a portion of the side surfaces is configured to be resilient and extendible along a depth of a mattress such that said contour sheet is releasably secured to the mattress.

14. The contour sheet of claim 13, wherein at least a portion of the side surfaces is provided with at least one resilient member configured to be extendible along the depth of the mattress.

15. The contour sheet of claim 14, wherein said at least one resilient member is further configured to be sandwiched between one or more layers of a fabric.

16. The contour sheet of claim 14, wherein said at least one resilient member is attached along corners that conform with corners of the mattress.

17. The contour sheet of claim 14, wherein said resilient members are provided in a spaced apart manner along the side surfaces.

18. The contour sheet of claim 13, wherein at least a portion of the side surfaces is provided with sets of resilient members, each of said sets of resilient members comprising a plurality of resilient members configured to be extendible along the depth of the mattress.

19. The contour sheet of claim 18, wherein each of said plurality of resilient members constituting said sets of resilient members is further configured to be sandwiched between one or more layers of fabric.

20. The contour sheet of claim 18, wherein said sets of resilient members are attached along corners that conform with corners of the mattress.

21. The contour sheet of claim 18, wherein said sets of resilient members are provided in a spaced apart manner along the side surfaces.

22. The contour sheet of claim 18, wherein said sets of resilient members are configured to provide an elongation ratio of about 1:3 or more of the un-extended to extended length of the side surfaces along the depth of the mattress.

23. The contour sheet of claim 14, wherein the at least one resilient member is attached in a vertical direction along the depth of the mattress or at an angle relative to the vertical direction.

24. The contour sheet of claim 14, further comprising L-shaped or V-shaped edges at the corners that conform with corners of the mattress.

25. The contour sheet of claim 24, wherein the at least one resilient member is attached to one or both edges of the L-shaped or V-shaped edges.