Abstract:
A duvet cover is comprised of a base sheet and a top sheet interconnected together by a peripheral stitched seam. A down feather sheet is retained between the base sheet and the top sheet. The down feather sheet has a substantially constant density of down feathers with the down feathers being retained captive by a binder thereby the duvet cover has a susbstantially constant insulating factor throughout because the down feathers are immovably retained therein. Such a duvet cover permits the creation of all sorts of stitched or quilted designs therein without concern for the propagation of the down feathers between the base sheet and the top sheet of the duvet which would create irregular insulation.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to duvet covers and more particularly to a down cover having an internal down feather sheet of substantially constant thermal efficiency, or fill power and wherein the down feathers are prevented from displacement during fabrication and use of the duvet cover. 
       BACKGROUND OF THE INVENTION 
       [0002]    Duvet covers having down insulation trapped between the base sheet and top sheet of the duvet cover are well known in the art. It is also well known that down feathers provide excellent insulating properties. The higher the fill power (fluffiness) of the down and therefore the more air trapped in the down, the more insulating ability an ounce of the down will have. Down is also a very light product that is desirable for insulation and particularly with products wherein weight is a factor, such as articles of apparel, sleeping bags, duvet covers, etc. However, down is a difficult product to work with due to its fluffy nature and unstable condition. It can also be hazardous to one&#39;s health has its fluffy miniscule filaments easily propagate into the surrounding air. For this reason work personnel are advised to wear breathing masks. 
         [0003]    Articles of apparel and bedding manufactured with down feather insulation are constructed by entrapping the down between opposed fabric sheets. To prevent the down from displacement, the fabric sheets are sewn with quilt stitched patterns. Some of these patterns are produced by cross-stitches to form small pockets in which the down feathers are trapped. See U.S. Pat. No. 5,692,245 as an example. With bedding products, such as duvet cover, the quilt stitches may be spaced apart from about 1 inch to 10 inches forming pockets with loose down therein. During use of these products, the down shifts within the pockets and form areas where the down is concentrated and other areas where there is much less down or no down. This results in areas where there is too much insulation or not enough insulation. Furthermore, because the down is loose between the fabric sheets at the time of stitching, the down is not uniformly distributed between the fabric sheets resulting in stitching being done Over heavy down underlay or no down at all creating irregularities in the stitched seams which are visible to the eye or resulting in a rejection of the manufactured product. Because duvet covers are made with large cross stitched quilt patterns and consequently large pockets for retaining the down, the down will propagate to corners of these pocket and unevenly therein. In the case of duvet covers having no quilt stitches, the down always propagate into regions and it is then necessary to shake the duvet in an attempt to distribute the down substantially evenly therein but such is near to impossible. Accordingly, the duvet cover has to be shaken constantly due to the unstable nature of the down. 
         [0004]    U.S. Pat. No. 6,025,041 addresses the problem of using the loose fluffy down feathers in the manufacture of articles and relates to a method of forming a down feather sheet of substantially constant thickness and particularly for use in the fabrication of articles of apparel such as described in U.S. Pat. No. 5,692,245. 
         [0005]    It is also desirable with duvet covers to provide different thermal properties for each sleeping side of a bed, as described and demonstrated in US Patent Publication 2005/0268399. It is also well known that the body of a person, when sleeping, requires less covering and thermal insulation in certain sections of its body. 
         [0006]    It would also be desirable to manufacture light weight duvet covers having esthetically pleasing stitch patterns and designs without concern to the size of the spaces formed between the design pattern stitch seams where loose down feathers could be unstable or the complexity of the stitch patterns. 
       SUMMARY OF THE INVENTION 
       [0007]    It is a feature of the present invention to provide a duvet cover which substantially overcomes the above mentioned disadvantages of prior art duvet covers and provides the above mentioned needs. 
         [0008]    Another feature of the present invention to provide a duvet cover having all sorts of stitched design pattern wherein the propagation of down feathers in irregular pockets formed by the stitch seam patterns is not an issue. 
         [0009]    A further feature of the present invention is to provide a duvet cover wherein pockets are formed to accommodate down feather sheets having different insulation factors. 
         [0010]    A still further feature of the present invention is to provide a duvet cover having a down feather sheet secured inside the duvet cover and which can be disposed in a deployed or stored position. 
         [0011]    According to the above features, from a broad aspect, the present invention provides a duvet cover which is comprised of a base sheet and a top sheet interconnected together by stitched seams. A down r sheet is retained between the base sheet and the top sheet. The down feather sheet has a substantially constant density of down feathers with the down feathers being retained captive by a binder. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0012]    A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which: 
           [0013]      FIG. 1  is a perspective view of a duvet cover constructed in accordance with the present invention and wherein a decorative stitched design pattern is formed in a section of the duvet cover; 
           [0014]      FIG. 2A  is a cross-section view of a down feather sheet comprised of down feathers held together by binder fibers and adhered on a backing sheet; 
           [0015]      FIG. 2B  is a cross-section view, similar to  FIG. 2A , but wherein the down feathers are held between opposed sheets; 
           [0016]      FIG. 3  is a plan view of a duvet cover wherein a down feather sheet is held captive between the base and top sheets of the duvet and a peripheral stitch seam; 
           [0017]      FIG. 4A  is a plan view of a duvet cover constructed in accordance with the prior art; 
           [0018]      FIG. 4B  is a partial cross-section view of prior art  FIG. 4A  showing the distribution of down feathers in the pockets: 
           [0019]      FIG. 5A  is a plan view of a duvet cover having large transverse pockets to retains down feather sheets having different thermal insulation factors; 
           [0020]      FIG. 5B  is a cross-section view, not to scale, of  FIG. 5A ; 
           [0021]      FIG. 5C  is a fragmented perspective view illustrating a stitched design pattern comprised of compressed stitched areas of different size and stitch line spacings; 
           [0022]      FIG. 6A  is a plan view of a duvet cover which is segmented into two half sections with the sections provided with a down feather sheet having different thermal insulation factors and wherein an irregular stitched design pattern is formed in the top sheet of the sections; 
           [0023]      FIG. 6B  is a cross-section view, not to scale, of  FIG. 6A ; 
           [0024]      FIG. 7  is a fragmented perspective view of a duvet cover wherein the down feather sheet is rolled to a bottom of the duvet cover, such as to remove the insulation factor of for ease of storage of the duvet cover; 
           [0025]      FIG. 8  is a fragmented cross-sectional view illustrating the rolled-up down feather sheet held captive in a pouch formed along the bottom edge inside the duvet cover; 
           [0026]      FIG. 9  is a plan view of the duvet cover formed of two independent longitudinal sections with each section formed in three transverse sections each having a double layer down feather sheet with the top layer being adapted to be rolled upon itself along a side edge of the duvet cover; 
           [0027]      FIG. 10  is a cross-sectional side view of the double layer down feather sheet; 
           [0028]      FIG. 11  is a plan view of a duvet cover with a single double down feather sheet with the top down layer rolled to a side and retain in a manner as shown in  FIG. 12 , and 
           [0029]      FIG. 12  is an enlarged fragmented cross-sectional view illustrating the top layer of the down sheet rolled on itself and retained by a holding flap. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0030]    Referring now to the drawings, and more particularly to  FIGS. 1 to 3 , there is shown a duvet cover  10  constructed in accordance with the present invention and disposed on a bed  11 . The duvet cover  10  is formed by a base sheet  12  and a top sheet  13  and a down feather sheet  14  disposed there between and interconnected together by stitched seams  15  or  16  or both. As shown in  FIG. 3 , stitched seams  15  are formed along the peripheral edges  16  of the duvet cover  10  to interconnect the base sheet  12  and the top sheet  13  and which forms a pocket in which the down feather sheet  14  is immovably trapped there between or sewn captive along one or more of the stitched seams  15 . As shown in  FIG. 1  the down feather sheet  14 , trapped between the base sheet  12  and the top sheet  13 , is additionally secured by irregularly disposed design pattern stitched seams  16  to give an esthetically pleasing appearance to the duvet cover without concern to the large areas or pocket, such as areas  17 , formed between stitch seams  16  spaced far apart as the down is held captive in the down feather sheet  14  and does not propagate. The stitch seams  16  extend through the top sheet  13 , the down feather sheet  14  and the base sheet  12 . Accordingly, the down heathers are not displaced when the duvet cover is manipulated during use. Also, the down feather sheet  14  provides a duvet cover with substantially uniform thermal insulating density throughout as well as uniform thickness. 
         [0031]    With reference to  FIGS. 2A and 2B , the down feather sheet  14  is comprised of loose down feathers  18  mixed with a binder herein polyethelene fibers  19  or a powder adhesive binder and deposited on a support backing sheet  20  where it is caused to bind by the application of heat to form a homogeneous down feather sheet.  FIG. 2B  shows another embodiment of the down feather sheet where the down is trapped and bound together and between opposed cover sheets  20  and  20 ′. The down feather sheet  14  may also be formed as disclosed in my above mentioned U.S. Pat. No. 6,025,041 where the down feathers are bound together to form a homogeneous sheet without the use of support fiber sheets wherein the down sheet is of very light weight. 
         [0032]    As shown in  FIG. 3 , a slit opening  21  may be formed adjacent an edge of the duvet cover, herein the top edge to remove the down feather sheet  14  when washing the duvet cover. A fabric slit cover flap  22  is formed by an over-turned edge portion of the base sheet  12  or the flap may be formed by a different fabric piece sewn on a top edge section of the duvet cover to conceal the slit. 
         [0033]      FIGS. 4A and 4B  illustrate some of the above mentioned prior art quilt pattern stitch seam designs formed in duvet cover to maintain the loose down feathers between the base sheet  25  and the top sheet  26 . As shown in  FIG. 4A , the quilt pattern stitch seams  24  produces small square pockets  27  into which down is held captive. However, the close spacing of the stitch seams makes it impossible to achieve a high loft in the down feathers trapped in these small pockets  27  and therefore limiting the insulation factor of the down in the duvet cover. As shown in  FIG. 4B , when larger pockets  27  are formed by spacing the stitch seam lines  24  further apart, the loosed down heathers  28  in the large pockets  27  are unstable, and as herein shown the down propagates unevenly in these large pockets to form down clusters  29  where the insulation factor is high, and areas  30  where there is very little or no down and wherein the insulation factor is very low. This creates a duvet cover with cold spots created by irregular distribution of the down and accordingly irregular thermal insulation. These prior art disadvantages are obviated by the duvet cover  10  manufactured according to the present invention. 
         [0034]    It is also desirable to also produce a duvet cover wherein a specific section or sections of the duvet cover has a different thermal insulating factor to form areas which are cooler on specific sections of the body or a user person. This is achievable with the present invention by different duvet designs formed by pattern stitch seams. Some of such designs are illustrated by  FIGS. 5A to 5C . As shown in  FIGS. 5A and 5B , the duvet cover  10 ′ is formed with three large transverse pocket sections  30 ,  30 ′ and  30 ″ in which there is retained a down feather sheet, with one or all of the sheets having a different thermal insulating factors or density. In the embodiment illustrated, the pocket section  30 ′ has an insulating factor inferior to the other two pocket sections  30  and  30 ″ to provide less insulation or warmth in the lower torso section of a person&#39;s body which is favourable to a person&#39;s health when asleep. The pocket sections are defined by transverse seam lines  31  extending across the duvet cover  10 ′. Slits  32  may be formed at the end of each pocket sections for insertion and removal of the down feather sheets. Each slit  32  is concealed by a flap  33  formed as previously described. 
         [0035]      FIGS. 6A and 6B  illustrate a further duvet cover  10 ″ wherein the duvet cover is sectioned longitudinally by a central stitch seam  34  to form two half pocket sections  35  and  35 ′ to receive therein a down feather sheet having different thermal insulating factors wherein a person sleeping on one side of the bed receives less warmth from the duvet cover  10 ″ than the person sleeping on the other side to suit the desire of the user persons. Again the down feather sheet is inserted and removed from these two sections through associated slits  36  and  36 ′ formed along an edge of the duvet cover and concealed by respective flaps  37  and  37 ′. If the down feather sheet is meant to be a fixed and non-removable part of the duvet cover  10 ″, deign stitch seams  38  may be formed in the duvet cover. 
         [0036]      FIG. 5C  illustrates a still further embodiment of the duvet cover of  FIG. 5A , wherein the sections  30 ,  30 ′ and  30 ″ do not contain a removable down feather sheet but a permanent down feather sheet and wherein the loft of the down feathers in their sections is modified by applying design stitch seam patterns formed by stitching. As shown the central transverse section  30 ′ has a design pattern throughout with design portions in the pattern having close stitch lines, such as portion  40 , to compress the down feathers in that section thereby reducing the loft of the down and the air trapped therein to provide down compressed zones of less thermal insulating efficiency. Other design portions are formed as small square portions  41  wherein the down is less compressed than in the portion  40  but more compressed than in the adjacent section  30  whereby to form a band or section  30 ′ having an overall reduced thermal insulation efficiency than the adjacent sections  30  and  30 ′ to achieve the same result as the embodiment illustrated in  FIG. 5A  while providing an esthetic patch design feature in a large band extending across the duvet cover  10 ′ Because the down feathers are not loosely retained between the base sheet  12  and the top sheet  13  all sorts of stitch designs can be made without concern of forming cold spots in the duvet cover due to loose down insulation. 
         [0037]    With reference now to  FIGS. 7 and 8  there is shown another embodiment of the duvet cover  10  of a type such as illustrated in  FIG. 3  wherein the down feather sheet  14  has a bottom edge section  14 ′ held captive by the peripheral seam  15 ′ formed in the lower edge of the duvet cover. The slit opening  21  provides access to the down feather sheet  14  to permit the down feather sheet to be rolled-up between the base sheet  12  and the top sheet  13  and stored in the bottom end of the duvet cover when not required during warmer weather periods. Still further a storage pouch  45  may be formed and attached in the lower peripheral seam  15 ′ to retained the down feather sheet roll captive therein. The pouch can be held closed by a zipper fastener of Velcro (Registered Trademark) fastener  46  as herein illustrated. The down feather sheet is made easily accessible by turning the base sheet and top sheet inside-out through the slit  21 . 
         [0038]    Referring now to  FIGS. 9 to 12  there is illustrated another embodiment of the present invention wherein the duvet cover  10 ″ is a two-sided duvet cover, a first side  50  and an adjacent second side  51 , such as for use on a king size bed. Each side  50  and  51  is divided into three transverse sections,  50 ′,  50 ″ and  50 ′″ for the first side and  51 ′,  51 ″ and  51 ′″ for the adjacent section  51 . In each of these sections the is secured a double layer down feather sheet  52 , as illustrated in  FIG. 10 . 
         [0039]    The bottom layer  53  of the double layer down feather sheet is secured to the base sheet  12  of the duvet cover adjacent a central longitudinal seam  56  by a snap attachment  55  or other suitable fastener or attachment. The tip layer  54  of the double layer down feather sheet  52  is detachably secured to the bottom layer  53  above the attachment  55  also by a snap attachment  56  or other suitable connection. Each down sheet layer  53  and  54  my have, for example, 50 grams/square meter of down feathers from goose or duch. Accordingly, the double layer sheet when folded provides insulation in the order of 100 grams/square meter. If the top layer  54  is rolled upon itself along the edge of the duvet cover the insulating factor in any of the transverse sections can be reduced by half. Accordingly, the user person can adapt its side of the duvet cover for its personal comfort. 
         [0040]    As shown in  FIG. 11  the top layer  54  has been rolled-up in a tight roll  60  along the edge  61  of the duvet cover and is retained in that position by one or more retaining flaps  57  sewn to the inside face of the top sheet  13  of the duvet cover  10 ′″. A Velcro (registered trademark) connector  58  is secured to the retaining flap  57  and to another like matting connector  59  secured to a predetermined location on the bottom down feather sheet  53 . Accordingly, the roll  60  is retained firmly in place. Every one of the transverse sections can be adjusted to suit the preference of each user person. 
         [0041]      FIG. 12  shows a duvet cover  10  having a double layer down feather sheet which can form a roll  65  of its top layer for storage along a side edge of the duvet cover. 
         [0042]    It is conceivable that the double layer down feather sheet can also be used in articles of apparel where the top sheet can be rolled to a concealing location and held in a pouch form with the article of apparel. Still, other applications the double layer down feather sheet are conceivable, 
         [0043]    It is within the ambit of the present invention to cover various obvious modifications of the embodiments and examples described herein provided such modifications fall within the scope of the appended claims.