HK1154058B - Knitted bed sheet - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a bed sheet constructed of high gauge circular knitted fabrics that accommodates and maintains optimum thermal conditions for sleep, which in turn can lead to faster sleep initiation and deeper, more restorative sleep.

2. Description of Related Art

Sleep problems in the United States are remarkably widespread, affecting roughly three out of four American adults, according to research by the National Sleep Foundation (NSF). Consequently, a great deal of attention has been paid to the circumstances surrounding poor sleep, along with strategies for how to improve it.

The implications are not merely academic. Sleep - not only the right amount of it but also the right quality - impacts not just day-to-day performance, but also "the overall quality of our lives," according to the NSF. Addressing the causes of poor quality sleep, therefore, has ramifications for millions.

Though many factors contribute to sleep quality, the sleep environment itself plays a critical role, and sleep researchers routinely highlight temperature as one of the most important components in creating an environment for optimal sleep. As advised by the University of Maryland Medical Center, "a cool (not cold) bedroom is often the most conducive to sleep." The National Sleep Foundation further notes that "temperatures above 24C (75 degrees Fahrenheit) and below 12C (54 degrees) will disrupt sleep," with 18C (65 degrees) being the ideal sleep temperature for most individuals, according to the NSF.

A lower environmental temperature is not the only thermal factor associated with improved sleep. Researchers have noted a nightly drop in body temperature among healthy, normal adults during sleep. This natural cycle, when inhibited or not functioning properly, can disrupt sleep and delay sleep onset, according to medical researchers at Cornell University. Conversely, the researchers noted, a rapid decline in body temperature not only accelerates sleep onset but also "may facilitate an entry into the deeper stages of sleep."

Therefore, maintaining an appropriately cool sleep environment and accommodating the body's natural tendency to cool itself at night should be a top priority for individuals interested in optimizing their sleep quality. Performance fabrics crafted into bedding applications would be uniquely capable of promoting cool, comfortable - and therefore better - sleep, as these advanced fabrics maximize breathability and heat transfer. Performance fabrics are made for a variety of end-use applications, and can provide multiple functional qualities, such as moisture management, UV protection, anti-microbial, thermo-regulation, and wind/water resistance.

There has been a long felt need in several industries to provide improved bedding to help individuals get better sleep. Such improved bedding would include beneficial wicking among other properties. For example, in marine, boating and recreational vehicle applications, bedding should resist moisture, fit odd-shaped mattresses and beds, and reduce mildew. Particularly with watercraft, there is a need to protect bedding, and specifically sheets, from moisture and mildew accumulation.

An additional problem with bedding, not just with marine and recreational vehicles, is the sticky, wet feeling that can occur when the bedding sheets are wet due to body sweat, environmental moisture, or other bodily fluids. In particular, when bedding is used during hot weather, or is continuously used for a long time by a person suffering from an illness, problems can arise in that the conventional bed sheet of cotton fiber or the like cannot sufficiently absorb the moisture. All of these issues lead to poor sleep.

To date, large circular knit performance fabric bed sheets are not known. There are width limitations in the manufacturing of high gauge circular knit fabrics, because the finished width of bedding fabrics are dictated by the machine used in its construction. At present, performance fabrics are manufactured with a maximum width of under 229 cm (90 inches) wide, given present manufacturing and technical limitations, along with the inability of alternate manufacturing processes to produce a fabric with identical performance attributes. Yet, normal bed sheet panels can be 259 by 231 cm (102 by 91 inches) or larger. Thus, performance fabrics cannot yet be used for bed sheets.

Some conventional solutions for the above issues that hinder a good night's sleep include United States Patent 4,648,186 , which discloses an absorbent wood pulp cellulose fiber that is provided in a variety of sizes and is placed under a mattress. The wood pulp is water absorbent and acts to capture moisture to prevent such moisture from being retained by the bedding or the bedding sheets. However, this proposed solution does not interact with the bedding or the bedding sheets, but merely acts as a sponge for moisture that is in proximity to the target bedding.

United States Patent 5,092,088 discloses a sheet-like mat comprised of a mat cover, the inside of which is divided into a plurality of bag-like spaces, and a drying agent packed into a bag and contained in the bag-like spaces in such a manner that the drying agent cannot fall out of the bag-like spaces. A magnesium sulfate, a high polymer absorbent, a silica gel or the like can be used as the drying agent. As can be seen, this proposed solution to moisture in bedding is cumbersome and chemically-based.

In the athletic apparel industry, moisture wicking fabric has been used to construct athletic apparel. For example, United States Patent 5,636,380 discloses a base fabric of CoolmaxQ high moisture evaporation fabric having one or more insulating panels of ThermaxB or ThermastatQ hollow core fiber fabric having moisture wicking capability and applied to the inner side of the garment for skin contact at selected areas of the body where muscle protection is desired. However, this application cannot be applied to bedding sheets due to the limitations of the size of the performance fabrics manufactured. Further, performance fabric such as this type cannot be easily stitched together as the denier is so fine that stitching this fabric results in the stitching simply falling apart.

A fitted bed sheet formed from a circular kaitted fabric is disclosed in US 5765 241A .

Circular knitting is typically used for athletic apparel. The process includes circularly knitting yarns into fabrics. Circular knitting is a form of knitting where the knitting needles are organized into a circular knitting bed. A cylinder rotates and interacts with a cam to move the needles reciprocally for knitting action. The yarns to be knitted are fed from packages to a carrier plate that directs the yarn strands to the needles. The circular fabric emerges from the knitting needles in a tubular form through the center of the cylinder. This process is described in United States Patent 7,117,695 . However, the machinery presently available for this method of manufacture can only produce a fabric with a maximum width of approximately 229 cm (90 inches). Therefore, this process has not been known to manufacture sheets having dimensions of 231 cm by 259 cm (91 inches by 102 inches) or greater.

Further, the machinery that is used for bedding is very different than for athletic wear. For example, bedding manufacturing equipment is not equipped to sew flatlock stitching . Bed sheets ean be knit using a flat bed process known as warp knitting, a

process capable of producing finished fabrics in the widths required for bedding. This method, however, cannot be employed to produce high-quality performance fabrics. Warp knitting is not capable of reproducing these fabrics' fine tactile qualities nor their omni-direction stretch properties, for example.

Circular knitting must be employed to produce a performance fabric that retains these fabric's full range of benefits and advantages. However, in order to produce a fabric of the proper width for a large bed sheet, a circular knit machine of at least 122 cm (48 inches) in diameter would be necessary. Manufacturing limitations therefore preclude the construction of a performance fabric at proper width for a large bed sheet. The industry is unsure if it could actually knit and then finish performance fabrics at these large sizes, even if the machinery were readily available.

Further, athletic sewing factories are typically not equipped to sew and handle large pieces of fabrics so that equipment limitations do not allow for the manufacture of bedding sheets.

A Large bed sheet of joined discrete fabrics according to the preamble of 1 is known from US 2008/002813A1 .

What is needed, therefore, is a large bed sheet that utilizes circular knitted performance fabric and its beneficial properties, which acknowledges and addresses limitations in the manufacture of the fabric. It is to such a bed sheet that the present invention is primarily directed.

BRIEF SUMMARY OF THE INVENTION

The present invention is a bed sheet according to present claim 1, and a method for manufacturing a bed sheat according to claim 8. The bed sheet has superior performance properties, while allowing for manufacture by machinery presently available and in use.

The first and second discrete performance fabrics can have different fabric characteristics. Fabric characteristics as used herein include, among other things, moisture management, UV protection, anti-microbial, thermo-regulation, wind resistance and water resistance.

The bed sheet can be used in, among other applications, residential settings, or in marine, boating and recreational vehicle environments.

The present bed sheet offers enhanced drape and comfort compared to traditional cotton bedding, and are as fine as silk, yet provide the benefits of high elasticity and recovery along with superior breathability, body-heat transport, and moisture management as compared to traditional cotton bedding.

The high gauge circular knit fabrics of the present bed sheet stretch to fit and offer superior recovery on the mattress allowing the sheet to conform to fit the mattress without popping off the corners of the mattress or billowing. The performance fabric includes pandex, the bed sheet offers a better fit than conventional bedding products, can accommodate larger or smaller mattress sizes with a single size sheet, and can conform to mattresses with various odd dimensions.

Spandex - or elastane - is a synthetic fiber known for its exceptional elasticity. It is stronger and more durable than rubber, its major non-synthetic competitor. It is a polyurethane-polyurea copolymer that was invented by DuPont. "Spandex" is a generic name, and an anagram of the word "expands." "Spandex" is the preferred name in North America; elsewhere it is referred to as "elastane." The most famous brand name associated with spandex is Lycra, a trademark of Invista.

The present bed sheet comprising gauge circular knit fabric offers durability in reduced pilling and pulling when compared to other knit technologies, and offer reduced wrinkles and enhanced color steadfastness

In a preferred embodiment, a one-size fitted bed sheet can actually fit two different size mattresses. For example, a full fitted bed sheet of the present invention can fit on both a full and queen size bed. A twin fitted bed sheet of the present invention will also fit an XL twin. In a boating application, the present invention can be produced to fit almost every large boat mattress.

Testing of the present invention conducted at the North Carolina State University (NCSU) Center for Research on Textile Protection and Comfort confirms that the present bed sheet provides a cooler sleeping environment than cotton. Performance bedding was tested side-by-side with commercially available cotton bed sheets in a series of procedures designed to measure each product's heat- and moisture-transport properties, as well as warm/cool-to-touch thermal transport capabilities.

Across all tests, the performance fabrics in bedding outperformed cotton, demonstrating the performance fabric's superiority in establishing and maintaining thermal comfort during sleep. This advantage is evident to users from the very onset, as NCSU testing indicates that, on average, The bed sheet of the present invention offers improved heat transfer upon initial contact with the skin, resulting in a cooler-to-the-touch feeling.

During sleep, a bed sheet of the present invention helps to maintain thermal comfort by trapping less body heat and breathing better than cotton. Testing has demonstrated that a bed sheet made out of performance fabrics transfers heat away from the body up to two times more effectively than cotton. This is critically important not only for sustained comfort during sleep, but also in terms of enabling the body to cool itself as rapidly as possible to facilitate sleep onset. In addition to trapping less heat, the bed sheet breathes better than cotton - up to 50% better, giving a strong advantage in terms of ventilation and heat and moisture transfer.

The performance advantage over cotton holds true for simulated dry and wet skin conditions, confirming that certain bed sheets are better suited than cotton at managing moisture (e.g., sweat) to maintain thermal comfort. In addition to wicking moisture away from the skin through capillary action, the bed sheet's advanced breathability further enables heat and moisture transfer through evaporative cooling. As a result, the user is kept cooler, drier and more comfortable than with cotton.

The present bed sheet holds a distinct advantage over cotton in enabling, accommodating and maintaining optimum thermal conditions for sleep, which in turn can lead to faster sleep initiation and deeper, more restorative sleep.

These and other objects, features and advantages of the present invention will become more apparent upon reading the following specification in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

• Fig. 1 illustrates a preferred embodiment of the present invention.
• Fig. 2 illustrates another preferred embodiment of the present invention.
• Fig. 3 illustrates a further preferred embodiment of the present invention.
• Fig. 4 illustrates another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Although preferred embodiments of the invention are explained in detail, it is to be understood that other embodiments are contemplated. Accordingly, it is not intended that the invention is limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, in describing the preferred embodiments, specific terminology will be resorted to for the sake of clarity.

It must also be noted that, as used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to a sheet or portion is intended also to include the manufacturing of a plurality of sheets or portions. References to a sheet containing "a" constituent is intended to include other constituents in addition to the one named.

Also, in describing the preferred embodiments, terminology will be resorted to for the sake of charity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

Ranges may be expressed herein as from "about" or "approximately" one particular value and/or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value.

By "comprising" or "containing" or "including" is meant that at least the named compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, method steps, even if the other such compounds, material, particles, method steps have the same function as what is named.

It is also to be understood that the mention of one or more method steps does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Similarly, it is also to be understood that the mention of one or more components in a fabric or system does not preclude the presence of additional components or intervening components between those components expressly identified.

Referring now in detail to the drawing figures, wherein like reference numerals represent like parts throughout the several views, the present invention of Figs. 1 and 4 provides a bed sheet 10 shown having dimensions of 259 cm (102 inches) in length and 231 cm (91 inches) in width. The material is manufactured from performance fabric, which includes Lycra, and for example, varying amounts of one or more of Coolmax, Thermax and Thermastat. In a preferred embodiment, the fabric is treated so that the fabric has antimicrobial properties. By using circular-knit performance fabric, the fabric is able to provide elasticity in all four directions. This property allows for the sheet to fit extraordinary mattress, cushion and bedding shapes, as well as providing better fits for traditional rectangular sheets. By using performance fabrics, the sheet has elastic properties that allow stretching in the directions shown as 30. In addition, by using circular-knit performance fabric, the resulting bedding retains an exceptionally fine tactile quality critical for providing maximum levels of enhanced comfort.

Circular knitting, is less expensive, as it requires less set-up time. Circular knitting also provides greater multidirectional stretch.

In order to provide a bed sheet that exceeds the maximum dimensions of fabric that can be produced by available circular knitting machines, flat lock stitching 12 is used to join a plurality of portions resulting in a sheet that is 231 cm (91 inches) wide (as shown). In an exemplary embodiment, piping 11 can be included in close proximity to the stitching. The stitching can be the same color as the fabric of the sheet portions, or different color(s). The piping can be 1,9 cm (3/4 inch) straight piping without a cord or other filler. In one preferred embodiment, the stitching is 16 stitches per inch. Piping 11 can be included at one end of the sheet and can be the same or a different color as the sheet fabric.

For a fitted bed sheet, the sheet can include an elastic portion surrounding the edge of the fitted sheet to better keep the fitted sheet in place when placed on a mattress or other sleeping surface. A cord can be sewn into the edge of the fitted sheet and cinched around the mattress or other sleeping surface to better hold the fitted sheet in place.

Referring to Fig. 2 , a bed sheet is shown having dimensions of 231 cm (91 inched wide and 259 cm (102 inches) in length. In this embodiment, stitching 14 is shown 86 cm (34 inches) from an interior edge 18 of a main portion 16 and another stitch 14 at edge 20 of the sewn-on portion. Flat lock stitching can be used for the stitching. Piping can be applied at or in proximity to the stitching.

Referring to Fig. 3 , a non-rectangular shaped bed sheet is shown. In this exemplary embodiment, elastic can be included around the edge of the fitted sheet to better maintain the fitted sheet in position when placed on a sleeping surface. In one embodiment, pull ties 24 can be installed at various locations around the edge of the fitted sheet in order to assist in maintaining the fitted sheet secured to the sleeping surface. The pull tie can be cinched to increase tension around the edge of the fitted sheet as shown by 26.

Stitching used for securing the portions of the sheet together can include that shown as 28a. In another embodiment, the stitching used for securing the portion of fabric together is shown as 28b.

Referring to Fig. 4 , yet another preferred embodiment of the invention is shown. In this embodiment, the bed sheet can be assembled through stitching of differing fabrics for generating performance zones in the sheet. For example, zone 32 can have higher wicking properties than the other zones since this area is where the majority of the individual body rests. Areas 34a through 34d can have higher spandex or other elastic fabric properties so that the fit around a sleeping surface is improved. Area 36 may have thermal properties such as increased cooling since this area is generally where the individual's head lies. The pillow covers of pillows used by the individual also have differing properties from the remainder of the sheet, e.g., thermal properties.

The present invention encompasses a bed sheet that has superior performance properties while allowing for manufacture by machinery presently available and in use. Further, the invention is related to a method for making a bed sheet. When using a circular knitting machine, a high gauge performance fabric can only be made to a maximum width of 184cm (72.5 inches) without losing the integrity of the spandex in the fabric. Yet, normal sheet panels are 259 x 231cm (102 x 91 inches). This presents problems when manufacturing a bed sheet from performance fabric.

Additionally, special stitching techniques must be used given the thread density of the fabric. Using this special stitching, panels are sewn together to produce a bed sheet that is the proper size for standard bed sheets. Because discrete fabric portions/panels are used in the manufacture of the present bed sheet, panels can be selected that provide different properties for different areas of the bed sheet ( Fig. 4 ). Stitching or seams on the bed sheet can also allow for the ease of making the bed. Because the bed sheet is made from performance fabric with spandex, it stretches to permit multiple and custom sizing for applications in cribs, recreational vehicles and boats.

Circular knitting machines used for high gauge performance bedding fabrics are called high-gauge circular knitting machines, because of dense knitting with thin yarn. High gauge generally denotes 17 gauges or more. Seventeen gauges indicate that 17 or more cylinder needles are contained in one inch. Circular knitting machines of less than 17 gauges are referred to as low-gauge circular knitting machines. The low-gauge circular knitting machines are often used to knit outerwear.

"Yarn count" indicates the linear density (yarn diameter or fineness) to which that particular yarn has been spun. The choice of yarn count is restricted by the type of knitting machine employed and the knitting construction. The yarn count, in turn, influences the cost, weight, opacity, hand and drape of the resulting knitted structure. In general, staple spun yarns tend to be comparatively more expensive the finer their count, because finer fibers and a more exacting spinning process are necessary in order to prevent the yarn from showing an irregular appearance.

A top width in the 229 cm (90-inch) range is currently possible using a circular knit fabric formed on a 91-97 cm (36-38-inch) diameter machine, although higher levels of spandex in the performance fabric tend to pull the width in. In just one example, on a 76 cm (30-inch) diameter machine, the spandex can reduce an otherwise 239 cm (94-inch) circumference fabric tube to one with a 152-165 cm (60-65) inch) finished width.

A major limitation in finished width is not strictly a knitting concern but also concerns finishing. With performance fabric, it tends to sag in the middle - increasingly so with greater widths - making finishing difficult to impossible above a certain threshold. A possible 229 cm (90-inch) finished width is contingent upon having a good finishing set-up capable of handling the present performance fabric. This potential for difficulties would only become compounded at the larger widths required for bed sheets.

In a preferred process, the present bed sheet undergoes a heat setting finishing process. Applying a moisture-wicking finish to another bed sheet-like cotton - that can be produced at larger widths appears unlikely to match the moisture-control properties of the present bed sheet, as polyester itself is naturally moisture-resistant and there are physical actions (e.g. capillary action) at play. Further, the use of cotton comes at the expense of breathability and heat-transfer capabilities (as confirmed by laboratory testing) and stretchability.

Numerous characteristics and advantages have been set forth in the foregoing description, together with details of structure and function. While the invention has been disclosed in several embodiments, it will be apparent to those skilled in the art that many modifications, additions, and deletions, especially in matters of shape and arrangement of parts, can be made therein without departing from the invention as set forth in the following claims.

Claims (12)

1. A bed sheet at least 228.6 cm (90 Inch) wide comprising:

   a first fabric; and

   a second fabric;

   wherein the first and second fabrics are discrete and made of performance fabric which includes polynrethanepolynrea copolymere fiber;

   wherein the first and second fabrics are joined to form the bed sheet;

   characterized in that the first and second fabrics are circular knitted at a gauge of at least 17 gauges.
2. The bed sheet of claim 1, further comprising piping.
3. The bed sheet of claim 1, wherein the first and second performance fabrics have different fabric characteristics.
4. The bed sheet of claim 3, wherein fabric characteristics are selected from the group consisting of moisture management, UV protection, anti-microbial, thermo-regulation, wind resistance and water resistance.
5. The bed sheet of one of the claims 1 to 4, wherein the bed sheet provides superior breathability, body-heat transport, and moisture management as compared to traditional cotton bedding.
6. The bed sheet of one of the claims 1 to 5, wherein the performance fabric has omnidirectional stretch properties.
7. The bed sheet of one of the claims 1 to 6, wherein the performance fabric allows for a one-size fitted bed sheet to fit two different size mattresses.
8. A method of making a bed sheet at least 228.6 cm (90 Inch) wide comprising:

   circular knitting at least two discrete performance fabric portions, the performance fabric including polyurethanepolyurea copolymere fiber ; and

   stitching at least two discrete performance fabric portions together to form the bed sheet;

   wherein the performance fabric portions are knit at a gauge of at least 17 gauges.
9. The method according to claim 8, further comprising heat setting finishing the bed sheet.
10. The method according to claim 8, further comprising providing piping to the bed sheet.
11. The method according to claim 8, wherein the at least two discrete performance fabric portions have different fabric characteristics.
12. The method according to claim 11, wherein fabric characteristics are selected from the group consisting of moisture management, UV protection, anti-microbial, thermo-regulation, wind resistance and water resistance.