Abstract:
An infant mattress fits safely in a crib without any gap between the mattress and the walls or bars of the crib. A ring of memory foam surrounds the supporting foam layers of the mattress and forms a snug fit with the vertical bars of the crib regardless of whether the dimensions of the particular crib or mattress vary from their standard sizes. The memory foam ring intentionally renders the infant mattress somewhat larger than the inner dimensions of the crib. The ring compresses when the mattress is placed in a crib in which opposing side bars are separated by a distance that is smaller than the mattress width. The ring is formed by pouring foam into a rectangular mold around the supporting foam layers. Where the mattress includes pocket coils on the supporting foam layers, the ring of memory foam conforms to the outer row of pocket coils.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to mattresses, and in particular to infant mattresses that provide safe sleeping surfaces in cribs. 
       BACKGROUND INFORMATION 
       [0002]    Mattresses used in cribs for infants have conventionally resembled adult mattresses built to a smaller scale. For various reasons, however, the requirements of a crib mattress are different than what is required for adult sized mattresses, such as single, twin, queen and king sizes. For example, the weight of an infant is so much less than the weight of an adult that a regular mattress simply built to a smaller scale is too stiff and unyielding for a recumbent infant. Mattress designs that provide additional edge support to compensate for the effects of people sitting on the edge of their beds actually detract from the quality of a crib mattress. Fitting within the side bars or walls of a crib is another requirement that is not critical for an adult sized mattress that simply sits on top of a box spring. 
         [0003]    A stiff crib mattress cannot be forced to fit inside the crib if the mattress is too large. Even a conventional foam mattress, as opposed to an innerspring mattress, that is too large will bulge if the mattress is forced into a crib with smaller dimensions. Thus, crib mattresses are typically manufactured to be smaller than the standard crib size in order to provide some tolerance to compensate for variations in manufacturing processes of the crib and the mattress. For example, sizes vary even among individual cribs of the same model manufactured by the same company. Sizes of individual mattresses also vary even among the same model of crib mattress manufactured by the same company. Thus, to ensure that a crib mattress fits any particular crib, the typical conventional crib mattress can be a couple of inches too short and too narrow. 
         [0004]      FIG. 1  (prior art) shows a conventional crib assembly  10  including a crib  11  and an infant mattress  12 . The outer dimensions of infant mattress  12  are smaller than the inner dimensions of the bars  13  that form a frame around the mattress. Consequently, there is a gap  14  between the edges  15  of mattress  12  and bars  13 . Gap  14  is dangerous because an infant could become trapped in gap  14  between mattress  12  and bars  13 . The baby&#39;s hands, legs or even head could become wedged between crib  11  and ill fitting mattress  12 . 
         [0005]      FIG. 2  (prior art) shows a conventional way of trying to prevent an infant from becoming trapped between an ill fitting infant mattress and the crib. Crib assembly  16  includes crib  11 , infant mattress  12  and a bumper assembly  17 . Bumper assembly  17  can be made of four connected side pieces that fit around the inside edges of crib  11  above mattress  12 . Bumper assembly  17  is intended to cover any gap between mattress  12  and bars  13 . In addition, bumper assembly  17  covers bars  13  to a height that a recumbent infant is likely to reach. A twisting and turning infant, however, invariably manages to insert a limb under bumper assembly  17  that can become lodged between a bar of the crib  11  and mattress  12 . In  FIG. 2 , an infant has lodged his left foot in a gap  14  between mattress  12  and a bar  18 . 
         [0006]    An infant mattress and a crib assembly are sought that prevent infants from becoming trapped between the mattress and a standard crib. 
       SUMMARY 
       [0007]    An infant mattress includes a first foam layer and a ring of visco-elastic foam. The first foam layer of the infant mattress is no greater than fifty-two inches long and twenty-eight inches wide. The ring of visco-elastic foam surrounds the mattress and abuts the four side surfaces of the first foam layer. The ring forms a snug fit with the vertical bars or walls of a crib regardless of whether the dimensions of the particular crib or mattress vary from their standard sizes. Thus, the infant mattress fits safely in the crib without any gap between the mattress and the bars of the crib. 
         [0008]    The ring of visco-elastic foam has a width of at least one inch and extends in a vertical dimension at least from the bottom surface to the top surface of the first foam layer. The ring is no more than two inches thick. The memory foam ring intentionally renders the infant mattress somewhat larger than the inner dimensions of the crib. The ring of visco-elastic foam is adapted to compress when the mattress is placed horizontally in a crib having opposing side bars separated by a distance that is smaller than the width of the mattress. The ring is formed by pouring foam into a rectangular mold around the first foam layer. Where the mattress includes pocket coils on the supporting foam layers, the ring of memory foam conforms to the outer row of pocket coils. 
         [0009]    In one embodiment, the mattress has a second foam layer whose bottom surface is in contact with the top surface of the first foam layer. The first and second foam layers have equal length dimensions and equal width dimensions. The first foam layer is made of high-density polyurethane foam, and the second foam layer is made of visco-elastic foam. 
         [0010]    In another embodiment, the mattress has rows of metal coils in fabric pockets on the top surface of the first foam layer. The fabric pockets of the outer row form an outer surface of half cylinders. Where the ring is formed by pouring foam into a rectangular mold around the first foam layer, the ring of visco-elastic foam conforms to the outer surface of half cylinders. 
         [0011]    A crib assembly includes an infant mattress resting on the mattress platform of a crib. Vertical bars are positioned peripherally around the mattress platform. The mattress includes a first foam layer and a ring of visco-elastic foam that abuts the four side surfaces of the first foam layer. The ring of visco-elastic foam has an uncompressed width of at least one inch and extends in a vertical dimension from at least the bottom surface to the top surface of the first foam layer. The width of the mattress is compressed between the vertical bars on one side of the mattress platform and the vertical bars on the opposing side of the mattress platform when the ring of visco-elastic foam is compressed by the vertical bars on opposite sides of the mattress. There is no gap between the mattress and any of the vertical bars positioned peripherally around the mattress platform. 
         [0012]    A method includes placing an infant mattress having a ring of memory foam on the support platform of a crib having vertical bars positioned peripherally around the platform. The mattress has a foam layer and a ring of visco-elastic foam that abuts the four side surfaces of the foam layer. The ring has a width of at least one inch and extends in a vertical dimension at least from the bottom surface to the top surface of the foam layer. The width of the ring of visco-elastic foam is compressed by the vertical bars when the mattress is placed on the platform. Moreover, the width of the mattress is compressed between the vertical bars on one side of the platform and the vertical bars on the opposing side of the platform. After the mattress is placed on the platform there is no gap between the mattress and any of the vertical bars positioned peripherally around the platform. 
         [0013]    In another embodiment, a crib assembly includes a foam layer of a mattress, a rectangular mattress platform with vertical bars positioned peripherally around the platform, and means for preventing a gap between the mattress and any of the vertical bars. The mattress rests on the mattress platform between the vertical bars. The means abuts the four side surfaces of the foam layer and is compressed by the vertical bars. The inner width of the crib extends from the vertical bars on one longer side of the rectangular platform to the vertical bars on the opposing longer side of the platform. The width of the foam layer is less than the inner width of the crib. 
         [0014]    A novel mattress cover adapts a conventional infant mattress to fit snuggly into a crib despite small variations in the dimensions of the infant mattress. The mattress cover includes a ring of visco-elastic foam that surrounds the perimeter of the conventional infant mattress when the mattress cover is placed over the infant mattress. A single piece of visco-elastic foam that forms the ring is glued to the insides of a fabric cover of the mattress cover. Alternatively, the fabric cover includes pockets that contain four foam side pieces that make up the foam ring. The mattress cover is held in place over the infant mattress by an elastic band that pulls the bottom edges of the fabric cover tight and maintains a stretched, flat top surface of the fabric cover over the mattress. 
         [0015]    Further details and embodiments are described in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The accompanying drawings illustrate embodiments of the invention. 
           [0017]      FIG. 1  (prior art) is a perspective view of a conventional crib assembly showing a gap between the edges of an infant mattress and the bars of the crib. 
           [0018]      FIG. 2  (prior art) is a perspective view of a bumper assembly that fits above a conventional infant mattress and around the inside edges of a crib and that is unsuccessful at preventing an infant from trapping a limb between the mattress and the bars of the crib. 
           [0019]      FIG. 3  is a cut-away perspective view of a novel infant mattress that fits snuggly into a crib despite variations in crib and mattress dimensions cause by inconsistent manufacturing processes. 
           [0020]      FIG. 4  is a top-down view of the novel infant mattress in a crib showing how a memory foam ring conforms around crib bars to absorb the excess width and length of the mattress compared to the inner dimensions of the crib. 
           [0021]      FIG. 5  is a cut-away perspective view of a novel infant mattress with pocket springs that fits safely into a crib despite variations in crib and mattress dimensions. 
           [0022]      FIG. 6  is a cut-away perspective view of the memory foam ring that conforms to the outer row of pocket coils. 
           [0023]      FIGS. 7A-C  are views of a novel mattress cover that includes a foam ring inside a fabric cover and that adapts a conventional infant mattress to fit snuggly into a crib. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 3  shows a cross-sectional view of an infant mattress  20  that fits snuggly into a crib despite variations from the stated crib dimensions cause by inconsistent manufacturing processes. In addition, infant mattress  20  fits snuggly into a crib despite small variations in the dimensions of the mattress cause by inconsistent manufacturing processes. Infant mattress  20  has a ring  21  of visco-elastic foam that surrounds the perimeter of the mattress. Visco-elastic foam is sometimes called memory foam. Typically, mattresses do not have a single layer of soft memory foam that extends from the sleeping surface through to the bottom of the mattress. A single layer of memory foam that extends from top to bottom around the perimeter of an adult size mattress would exacerbate the problem of poor edge support caused by people sitting on their mattresses. In a crib mattress, however, ring  21  of memory foam is squeezed into bars  13  of the crib and leaves no gap between infant mattress  20  the bars. Consequently, a crib assembly that includes infant mattress  20  is safer because there is no gap  14  in which an infant&#39;s limb could become lodged. 
         [0025]    The embodiment of  FIG. 3  is a foam mattress that includes a plurality of foam layers whose length and width dimensions are nearly as large as the support surface for the mattress. Ring  21  of visco-elastic foam abuts each of the foam layers on all four sides.  FIG. 3  shows an underlying layer  22 , a middle layer  23 , and a topper layer  24 . Underlying layer  22  is made of regular high-density polyurethane foam and provides the stability and underlying support for infant mattress  20 . Middle layer  23  is made of memory foam and provides a first cushioning interface of mattress  20 . In this embodiment, the memory foam of middle layer  23  has a high density, for example, greater than three pounds per square foot. Memory foam middle layer  23  has an egg crate pattern on its bottom surface. Utilizing an egg crate pattern on at least one surface provides a softer feel normally associated with lower density foam even when higher density foam is used that is inherently more stable. 
         [0026]    Topper layer  24  is a fibrous padding layer above the foam middle layer  23 . As noted above, foam mattresses are typically produced from polymeric compounds. Sleeping on these polymeric compounds is not unlike sleeping on a plastic tarp. It may not be healthy for an infant to lie on a non-breathable foam surface. For example, it may be that sudden infant death syndrome (SIDS) is caused by the accumulation of carbon dioxide in bedding. If the upper layer of an infant mattress is air impermeable, carbon dioxide is more likely to build up around an infant&#39;s face as the infant exhales while lying on her stomach. Fibrous top padding layer  24  is air permeable and is more likely to allow exhaled carbon dioxide to dissipate. Infant mattress  20  has a quilted cover  25  made of terry cloth or some other natural fiber weave. Cover  25  covers all sides of mattress  20 , including the outer surfaces of ring  21 . 
         [0027]    The length and width dimensions of middle layer  23  and topper layer  24  are the same as those of underlying layer  22 . In one embodiment, underlying layer  22  is three inches thick, middle layer  23  is two inches thick, and topper layer  24  is one inch thick. The foam of middle layer  23  is glued to the top of underlying layer  22 . Likewise, the bottom of topper layer  24  is glued to the top of middle layer  23 . The quilting of cover  25  is stitched into topper layer  24 . Ring  21  of visco-elastic foam is glued to the sides of layers  22 - 24 . In one embodiment, ring  21  is made of four separate pieces resembling a picture frame. In another embodiment, layers  22 - 24  are placed in a mold, and memory foam is poured around the layers forming a ring that is a single piece of foam. In one embodiment, the width of ring  21  around layers  22 - 24  is about one inch. Thus, there is a total of about two inches of squeezable space in each of the length and width dimensions of infant mattress  20 . In other embodiments, the width of ring  21  is more than one inch. Inasmuch as memory foam is more costly than HD foam, cost can be reduced by not making ring  21  thicker than required to compensate for the largest probable variations in the manufactured dimensions of mattress  20  and crib  11 . It is unlikely that a mattress will be more than one inch too long or too wide, and it is unlikely that the interior dimensions of a crib will be more than one inch too short or too narrow. 
         [0028]    The standard inner dimensions of a crib as defined by the Juvenile Products Manufacturers Association are 51⅝ inches by 27¼ inches. Thus, the total dimensions of infant mattress  20  can be slightly larger and will still fit within a standard size crib without bowing or buckling. Ring  21  of visco-elastic foam is compressed at the location of the bars  13  of the crib and absorbs any excess length or width of the mattress. For example, an infant mattress  20  that is twenty-nine inches by fifty-three inches fits within the standard size crib leaving no gap between ring  21  and the crib bars or walls. For the safety of the baby, mothers are advised that no more than two of their fingers should fit between the mattress and the crib. In comparison, there is no room for even one finger between ring  21  and the crib. 
         [0029]      FIG. 4  illustrates how the memory foam of ring  21  conforms around crib bars  13  to absorb the excess width and length of infant mattress  20  compared to the inner dimensions of crib  11 . The boundary  26  of memory foam ring  21  around the layers  22 - 24  is indicated with a dashed line.  FIG. 4  shows that there is no gap between infant mattress  20  and the bars of crib  11 , even if the particular mattress  20  is manufactured somewhat smaller than the stated dimensions and even if the inner dimensions of crib  11  are manufactured somewhat larger than the stated dimensions. 
         [0030]      FIG. 5  shows a cross-sectional view of another embodiment of an infant mattress  27  that fits safely into a crib despite variations from the stated dimensions of the mattress and the crib. Infant mattress  27  is an innerspring mattress with a ring  21  of visco-elastic foam that surrounds underlying layer  22  as well as rows of metal spring coils  28  in fabric pockets  29 . The metal coils  28  are supported by underlying layer  22 . Each of the metal coils  28  is made of a separate piece of metal instead of one wire being bent to form multiple metal coils. Each of the metal coils  28  is enclosed in a separate fabric pocket  29 . Fiber padding may be inserted into each fabric pocket  29  inside of each metal coil  28 . The fabric of one row of pockets  29  is glued to the fabric of the next row of pockets  29 . In embodiments in which memory foam ring  21  is formed by pouring foam in a mold into which underlying layer  22  and coils  28  have been placed, the foam flows around the outer row of fabric pockets  29  and provides stability to infant mattress  27 . As the liquid memory foam cures it naturally affixes itself to both the periphery of the fabric pockets and to the sides of underlying layer  22 . Infant mattress  27  has a quilted cover  30  that is thicker than the cover  25  of mattress  20 . Cover  30  includes filler material that lies on top of the metal coils  28 . The filler material is quilted to the fabric of cover  30  and can be visco-elastic foam, high density (HD) foam or fiber padding. 
         [0031]      FIG. 6  shows a cut-away view of just ring  21  in the embodiment in which ring  21  is formed in a mold around underlying layer  22  and coils  28  in fabric pockets  29 . The outer row of fabric pockets  29  forms an outer surface of half cylinders.  FIG. 6  shows that ring  21  of visco-elastic foam conforms to the outer surfaces of layer  22  and of the half cylinders and forms a complementary outline  31 . 
         [0032]      FIGS. 7A-C  show a novel mattress cover  32  that adapts a conventional infant mattress  12  to fit snuggly into a crib despite small variations in the dimensions of the mattress  12  cause by inconsistent manufacturing processes. Mattress cover  32  enables a consumer to achieve a safe fit between an existing infant mattress and a crib and obviates the need to buy a new better fitting mattress. Mattress cover  32  includes a ring  21  of visco-elastic foam that surrounds the perimeter of conventional infant mattress  12  when mattress cover  32  is placed over mattress  12 . In one embodiment, a fabric cover  33  of mattress cover  32  includes stitched fabric pockets that contain four foam side pieces that make up ring  21 . In another embodiment, a single piece of visco-elastic foam forming ring  21  is glued to the insides of fabric cover  33 , as shown in  FIG. 7A . In the embodiment in which a single piece of foam is glued to the fabric cover, the entire mattress cover  32  can be folded, compressed, rolled and air-sealed for shipment and sale. When the consumer unseals the package, mattress cover  32  expands to its normal size and is ready to place over a conventional infant mattress. 
         [0033]      FIG. 7B  is a cut-away perspective view showing how mattress cover  32  is held in place over infant mattress  12  by an elastic band  34  that pulls the bottom edge  35  of fabric cover  33  tight. The top fabric surface of fabric cover  33  is not shown in the cut-away view of  FIG. 7B . The top fabric surface of fabric cover  33  is stretched flat when the bottom edges are tightened by elastic band  34 .  FIG. 7C  shows mattress cover  32  from the bottom of conventional infant mattress  12 . The memory foam of ring  21  of mattress cover  32  conforms around the crib bars to absorb any deficient width or length of infant mattress  12  compared to the inner dimensions of the crib in a manner similar to that described in relation to the embodiment of  FIG. 4 . 
         [0034]    Although certain specific embodiments are described above for instructional purposes, the teachings of this patent document have general applicability and are not limited to the specific embodiments described above. Accordingly, various modifications, adaptations, and combinations of various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.