Abstract:
A mattress converts from a crib mattress with side walls and end walls surrounding an infant sleeping surface on a central mattress section therebetween to a twin mattress with a substantially planar sleeping surface to support a reclining child or adult. The end walls and side walls are tethered or hingedly connected to the central mattress section and are moveable from an upright position (crib mattress) to an open position (twin mattress). Sidewall extensions are hingedly connected to the side walls and are pivotably moveable from a first position above the side walls to a second position axially aligned with the side walls when the side walls are in the open position.

Description:
FIELD OF THE INVENTION 
     This invention relates to bedding mattresses convertible from a first size suitable for use in an infant&#39;s crib to a second size suitable for use with a twin bed. The bedding mattress has sections that are hingedly connected so that they may be pivotably moved from a first position forming a mattress combined with sidewalls or bumpers for use in an infant&#39;s crib to a second position forming a twin-size mattress. 
     BACKGROUND 
     Infants generally sleep in cribs, with structure surrounding the sleeping surface to prevent the infant from rolling or falling off the sleeping surface. Frequently, the structure surrounding the sleeping surface comprises bars or poles or solid sidewalls. Various forms of cushioning material, usually called crib bumpers, may be installed to surround the sleeping surface and cover at least a portion of the bars or poles to protect the infant from bumping his or her head, and from poking arms or legs outside of the crib. See, e.g., U.S. Pat. No. 6,957,464. 
     Toddlers and younger children usually begin to sleep on regular bedding mattresses, frequently twin-sized mattresses. The twin-sized mattresses do not fit within the crib structure. Some infant cribs are designed to be converted from a crib to a child&#39;s twin-sized bed. See, e.g., U.S. Pat. Nos. 5,754,993; 5,715,551; 4,525,883 and 4,361,919. 
     While the infant crib may be convertible to a twin-sized bed frame, parents still must purchase a twin-sized mattress to be used with the converted bed frame. Parents prefer multi-use childrens&#39; products, but the convertible cribs offered today do not come with convertible mattresses. 
     One convertible infant mattress is shown in U.S. Pat. Nos. 5,937,465 and 5,822,817. The mattress system defines a sleeping recess between upstanding walls in a configuration for use in a crib. The mattress system includes a separable accessory panel that is removed when the mattress system is installed in a crib. The accessory panel can be inserted into the recess, and the mattress system can then be inverted to provide a larger sleeping surface for a child as opposed to an infant. However, this mattress system with the accessory panel inserted still has the periphery dimensions of a crib mattress, and does not convert in size to that of a twin-size mattress. 
     A mattress that can be used in a crib for infants and converted to a twin-sized mattress for use on a standard bedding frame for toddlers and children continues to be sought. Moreover, crib mattresses that have upstanding sidewalls to serve as crib bumpers are desired by parents. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a crib mattress that is convertible to a twin-sized bedding mattress has a central mattress section defining a top surface and first and second ends and left and right sides. A first end wall is hingedly connected to the central mattress section at the first end, and the first end wall is pivotably moveable from an upright position to an open position. A second end wall is hingedly connected to the central mattress section at the second end, and the second end wall is pivotably moveable from an upright position to an open position. A first side wall is hingedly connected to the central mattress section at the left side, and the first side wall is pivotably moveable from an upright position to an open position. A second side wall is hingedly connected to the central mattress section at the right side, and the second side wall is pivotably moveable from an upright position to an open position. Each side wall may have one or more sidewall extensions hingedly connected to an end of the side wall and pivotably moveable from a first position to a second position. In the first position, the lengthwise axis of a respective sidewall extension is parallel or substantially parallel to the lengthwise axis of the respective side wall to which it is connected. In the second position, the lengthwise axis of a respective sidewall extension is generally aligned with the lengthwise axis of the respective side wall to which it is connected. When the first and second end walls are in the open position, the first and second side walls are in the open position, and sidewall extensions are in the second position, a substantially planar body-supporting surface is formed that includes the central mattress section, the first and second end walls, the first and second side walls, and, preferably, the sidewall extensions. 
     In a second embodiment, a crib mattress that is convertible to a twin-sized bedding mattress has a central mattress section defining a top surface and first and second ends and left and right sides. A first end wall is tethered to the central mattress section at the first end, and the first end wall is separable from the central mattress section and moveable from an upright position to an open position. A second end wall is tethered to the central mattress section at the second end, and the second end wall is separable from the central mattress section and moveable from an upright position to an open position. A first side wall is tethered to the central mattress section at the left side, and the first side wall is moveable from an upright position to an open position. A second side wall is tethered to the central mattress section at the right side, and the second side wall is moveable from an upright position to an open position. Each side wall may have one or more sidewall extensions hingedly connected to an end of the side wall and pivotably moveable from a first position to a second position. In the first position, the lengthwise axis of a respective sidewall extension is parallel or substantially parallel to the lengthwise axis of the respective side wall to which it is connected. In the second position, the lengthwise axis of a respective sidewall extension is generally aligned with the lengthwise axis of the respective side wall to which it is connected. When the first and second end walls are in the open position, the first and second side walls are in the open position, and sidewall extensions are in the second position, a substantially planar body-supporting surface is formed that includes the central mattress section, the first and second end walls, the first and second side walls, and, preferably, the sidewall extensions. 
     The sidewall extensions may define one or more voids therein to receive an accessory or toy when the mattress is in the crib configuration. 
     The central mattress section, first end wall, second end wall, first side wall, second side wall, and the sidewall extensions preferably are formed of foam, such as polyurethane foam, viscoelastic foam, and/or latex foam. The mattress components may be formed of multiple layers of foams of varying resiliency or support characteristic. For example, the body-contacting surfaces in the twin bed configuration may be of a more resilient or softer foam. Such more resilient or softer foam may be co-molded or bonded to a firmer foam for greater support. 
     The hinge connections between the mattress components may be formed of sheet-like materials, such as fabrics, films, laminates and elastics. The tethers between mattress components in the second embodiment may be formed of sheet-like materials, such as fabrics, films, laminates and elastics. 
     To enhance stability of the mattress in the upright configuration suitable for a crib mattress, releasable fasteners may be applied to end surfaces of the central mattress section and to surfaces of the first and second end walls to join the first and second end walls to the central mattress section in the upright position. Similarly, releasable fasteners may be applied to the top surface of the central mattress section and to surfaces of the first and second side walls to join the first and second side walls to the central mattress section in the upright position. Preferably, releasable fasteners may be applied to end surfaces of the side walls and to surfaces of the end walls to join the side walls to the end walls in the upright position. Preferably, releasable fasteners may be applied to lengthwise surfaces of the sidewall extensions and to lengthwise surfaces of the first and second side walls to join the sidewall extensions to the respective side walls. 
     To enhance stability of the mattresses in the open configuration suitable for a twin mattress, releasable fasteners may be applied to end surfaces of the central mattress section and to surfaces of the first and second end walls to join the first and second end walls to the central mattress section in the open position. Similarly, releasable fasteners may be applied to side surfaces of the central mattress section and to surfaces of the first and second side walls to join the first and second side walls to the central mattress section in the open position. Preferably, releasable fasteners may be applied to lengthwise surfaces of the sidewall extensions and to side surfaces of the first end wall to join the sidewall extensions to the first end wall when the first end wall is in the open position and the sidewall extensions are in the second position. 
     A cover may extend substantially over at least the substantially planar body-supporting surface. A cover may extend substantially over at least the central mattress section. A cover may extend over the entirety of the size convertible mattress. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described in the following detailed description with reference to the following drawings in which: 
         FIG. 1  is a perspective view of a crib configuration for a size-convertible mattress of one embodiment according to the invention; 
         FIG. 2  is a perspective view of the size-convertible mattress of  FIG. 1  in which end walls and side walls are partially disassembled from the crib configuration; 
         FIG. 3  is a perspective view of the size-convertible mattress of  FIG. 1  in which the end walls, side walls and sidewall extensions are in open position for a twin bed configuration; 
         FIG. 4  is a perspective view of the size-convertible mattress of  FIG. 1  in its twin bed configuration; 
         FIG. 5  is a longitudinal section taken along line  5 - 5  in  FIG. 1 ; 
         FIG. 6  is a transverse section taken along line  6 - 6  in  FIG. 1 ; 
         FIG. 7  is a partial perspective view of a crib configuration for a size-convertible mattress of a second embodiment according to the invention; 
         FIG. 8  is a perspective view of the size-convertible mattress of  FIG. 7  in which end walls and side walls are partially disassembled from the crib configuration; and 
         FIG. 9  is a partial perspective view of the size-convertible mattress of  FIG. 7  in its twin bed configuration. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , one embodiment of a size-convertible mattress is shown in a crib configuration  10 . The mattress in the crib configuration  10  has a central mattress section  12  surrounded by upstanding end walls  14 ,  16  and side walls  20 ,  22 . The central mattress section  12  is of a size having a generally planar sleeping surface to accommodate an infant or small child. The upstanding end walls  14 ,  16  and side walls  20 ,  22  serve as bolster cushions or protective barriers between the spindles or poles or side walls of the crib furniture and the sleeping surface of the central mattress section  12 . In its crib configuration  10  the mattress may have outer periphery dimensions comparable to a standard crib mattress, such as about 27 inches by 52 inches (69 cm by 131 cm). 
     The size-convertible mattress may be converted from its crib configuration  10  ( FIG. 1 ) to a twin mattress configuration  70  ( FIG. 4 ) upon rotating the end walls  14 ,  16  and side walls  20 ,  22  in a manner as described herein. In the crib configuration  10  ( FIG. 1 ), the side walls  20 ,  22  are removably joined to the planar top surface of the central mattress section  12  with fasteners  50 , such as hook and loop strips (sometimes referred to as Velcro® fasteners). In the crib configuration  10  ( FIG. 1 ), the end walls  14 ,  16  are removably joined to end portions of the side walls  20 ,  22  and sidewall extensions  24 ,  26 ,  28 ,  30  with fasteners  50 , such as hook and loop strips.  FIG. 6  illustrates the connections with fasteners  50  that hold the second end wall  16  to the ends of the first side wall  20  and second sidewall extension  26 . 
     The first and second end walls  14 ,  16  have hinges  40  formed at their bottom corners. For example, a first portion of a hinge  40  is joined or attached to an inner surface of the first end wall  14 , and a second portion of a hinge  40  is joined or attached to a top planar surface of the central mattress section  12 . See  FIG. 5 . Hinges  40  may be formed of a resilient material that may be repeatedly bent back and forth as desired for converting the mattress from a crib configuration  10  to a twin mattress configuration  70 . The hinges preferably are adhesively attached or flame laminated to surfaces of the mattress components. The hinges may be joined to the surfaces of the components forming the mattress with adhesive, or by flame lamination or by stitching or by other known attachment means. In flame lamination, foam surfaces may be heated to softening and the hinge material may be applied to the softened surface portion(s). Upon cooling, a bond between hinge material and foam material is formed. Possible materials to form the hinges include fabrics, such as nylons, rip-stop nylon, and CORDURA nylon. The fabrics may be woven, and may be coated with moisture-resitant barrier-coatings. 
     In the first mattress embodiment ( FIG. 1 ), the end walls may have dimensions of about 12 inches in height, 27 inches in length and 6 inches in width. The side walls may have dimensions of about 6 inches in height, 51 inches in length and 6 inches in width. The sidewall extensions may have dimension of about 6 inches in height, 20 inches in length and 6 inches in width. 
     As shown in  FIG. 2 , the first end wall  14  may be rotated about its hinge  40  and folded down in the direction of arrow  34  so as to lay flat. Compare  FIGS. 3 and 4  with  FIG. 2 . Upon rotating the first end wall  14 , the fasteners  50  holding the first end wall to end surfaces of the first and second side walls  20 ,  22  and first and third sidewall extensions  24 ,  28  are separated from one another. When fully opened, the inner side surface of the first end wall  14  forms a plane or substantially forms a plane with the planar top surface of the central mattress section  12  (See  FIGS. 3 and 4 ). 
     Similarly, the second end wall  16  may be rotated about its hinge  40  and folded down in the direction of arrow  34  so as to lay flat. Compare  FIG. 2  with  FIGS. 3 and 4 . Upon rotating the second end wall  16 , the fasteners  50  holding the second end wall to end surfaces of the first and second side walls  20 ,  22  and second and fourth sidewall extensions  26 ,  30  are separated from one another. When fully opened, the inner side surface of the second end wall  16  forms a plane or substantially forms a plane with the planar top surface of the central mattress section  12  (See  FIG. 4 ). 
     Still referring to  FIG. 2 , the first side wall  20  may be rotated about its hinge  42  in the direction of arrow  36  and folded down so as to lay flat. Compare  FIG. 2  with  FIGS. 3 and 4 . Upon rotating the first side wall  20 , the fasteners  50  holding one lengthwise side surface of the first side wall  20  to the top planar surface of the central mattress section  12  are separated from one another. In addition, the second side wall  22  may be rotated about its hinge  42  in the direction of arrow  36  and folded down so as to lay flat. Upon rotating the second side wall  22 , the fasteners  50  holding one lengthwise side surface of the second side wall  22  to the top planar surface of the central mattress section  12  are separated from one another. 
     When in the crib configuration  10 , the first and second sidewall extensions  24 ,  26  are held in contact with a side surface of the first side wall  20  with fasteners  50  (such as hook and loop fasteners). The longitudinal axes of the first and second sidewall extensions  24 ,  26  are generally in parallel with the longitudinal axis of the first side wall  20 . Once the first side wall  20  is in its open position, fasteners  50  may be released and first and second sidewall extensions  24 ,  26  may be rotated in the direction of arrows  38  ( FIG. 3 ) about hinges  44  to open positions in which the first and second sidewall extensions are axially aligned with the first side wall  20 . Alternatively, the first and second sidewall extensions  24 ,  26 , may be rotated when the first side wall  20  is in its upright position, but after the first and second end walls  14 ,  16  have been rotated to their open positions. See  FIGS. 3 and 4 . Similarly, the third and fourth sidewall extensions  28 , may be rotated about hinges  44  to open positions in which the third and fourth sidewall extensions  28 ,  30  are axially aligned with the second side wall  22 . 
     In the twin mattress configuration ( FIG. 4 ), the first and second end walls  14 ,  16  are unfolded down and aligned with surfaces generally planar with the generally planar top surface of the central mattress section  12 . In addition, the first and second side walls  20 ,  22  are unfolded down and aligned with surfaces generally planar with the generally planar top surface of the central mattress section  12 . Moreover, the first, second, third and fourth sidewall extensions  24 ,  26 ,  28 ,  30  are unfolded down and axially aligned with the first and second side walls  20 ,  22 . As so rotated and unfolded, the central mattress section  12 , first and second end walls  14 ,  16 , first and second side walls  20 ,  22  and first, second, third and fourth sidewall extensions  24 ,  26 ,  28 ,  30  together form a generally planar surface of a size of a twin bed mattress configuration  70  ( FIG. 4 ). Fasteners  50  (not shown) may be provided at facing surfaces to hold the various components together in the twin bed mattress configuration ( FIG. 4 ). 
     In the twin bed mattress configuration  70 , the mattress may have an outer periphery dimension comparable to a standard twin mattress, such as about 39 inches by 75 inches (99 cm by 191 cm). The twin bed mattress configuration  70  preferably has a thickness in the range of 6 to 18 inches (15 cm to 46 cm), more preferably about 6 inches (15 cm). The size convertible mattress may be encased in a removable cover (not shown), such as canvas, cotton sheeting, flannel or other suitable fabric, when in the twin bed mattress configuration  70  or the crib configuration  10 . 
     The size-convertible mattress may be folded back from the twin mattress configuration  70  ( FIG. 4 ) to the crib mattress configuration  10  ( FIG. 1 ) by releasing any fasteners between components and rotating the components about hinges  44 ,  42 ,  40  in the reverse direction from that shown to unfold the components from the crib configuration  10 . The components may be re-fastened together in the crib configuration  10 . 
     The mattress components are formed of one or more resilient materials suitable for holding a reclining infant, child or adult. In a preferred embodiment, the resilient material is a cellular polymer, such as polyurethane foam or latex foam. Cellular polyurethane structures (e.g., foams) typically are prepared by generating a gas during polymerization of a liquid reaction mixture generally comprised of a polyester or polyether polyol, an isocyanate, one or more surfactants, one or more catalysts and one or more blowing agents. The gas causes foaming of the reaction mixture to form the cellular structure. The surfactant(s) stabilize the structure and/or assist in cell opening. Polyurethane foams with varying density and hardness may be formed. Hardness is typically measured as IFD (“indentation force deflection”) or CFD (“compression force deflection”). Specifically, IFD 25  is the force required to compress the foam to 25% of its original thickness or height, and IFD 65  is the force required to compress the foam to 65% of its original thickness or height. Tensile strength, tear strength, compression set, air permeability, fatigue resistance, support factor, and energy absorbing characteristics may also be varied, as can many other properties. Specific foam characteristics depend upon the selection of the starting materials, the foaming process and conditions, and sometimes on the subsequent processing. 
     Viscoelastic polyurethane foams are characterized by high vibration damping, body conformance and slow recovery from compression. Most viscoelastic foams have densities in the range of from about 2.0 to 6.0 pounds per cubic foot (32 to 96 kg/m 3 ), but higher densities are sometimes desired (e.g., 8.0 pounds per cubic foot (128 kg/m 3 ) and higher). Viscoelastic foams have gained popularity for bedding applications because such foams are advertised as reducing pressure points, which are believed to cause tossing and turning during sleep. 
     Representative polyurethane foams suitable for mattresses and cushions, such as bolsters and pillows, include foams offered by FXI Foamex Innovations under brands REFLEX, REFLEX NATURAL, AERUS and AERUS NATURAL. Such foams may have densities in the range of about 1 to 10 pounds per cubic foot, preferably about 2 to 6 pounds per cubic foot, and IFD 25  in the range of 7 to 70 pounds per square inch. Representative latex foams suitable for mattresses and cushions, such as bolsters and pillows include latex foams offered by FXI Foamex Innovations under brand NATURAL LATEX FROM FXI. Such latex foams have densities in the range of about 1 pounds per cubic foot and up to about 30 pounds per cubic foot. 
     The central mattress section  12 , first and second end walls  14 ,  16 , first and second side walls  20 ,  22 , and first, second, third, fourth sidewall extensions  24 ,  26 ,  28 ,  30  are shown in  FIGS. 1-6  as dual components. In this embodiment, when the mattress is in the twin bed configuration ( FIG. 4 ), the top layer  72  forming the reclining surface of the mattress preferably comprises a resilient cellular polymer, such as polyurethane foam, or a slow-recovery foam, such as a viscoelastic foam, and the bottom layer  74  forming the supporting surface of the mattress comprises a firm polyurethane foam. For example, the top layer  72  may comprise an ENERGIA polyurethane foam with a density of 3 to 4 pounds per cubic foot, and the bottom layer  74  may comprise a REFLEX foam with a density of 3 to 4 pounds per cubic foot. As another example, the top layer  72  may comprise a polyurethane foam with a density of 4 pounds per cubic foot and an IFD 25  in the range of 35 to 65 pounds per square inch, and bottom layer  74  may comprise a viscoelastic foam with a density of 3.5 pounds per cubic foot and an IFD 25  of 12 pounds per square inch. 
     When the mattress is in the crib configuration  10  ( FIG. 1 ), preferably the firm layer  74  forms the body-supporting surface of the central mattress section  12 . When the mattress is in the twin bed configuration  70  ( FIG. 6 ), a user may position said mattress with either the firm layer  74  or the softer top layer  72  as the body-supporting surface. 
     To make a multi-layer configuration, the two different foam layers  72 ,  74  are joined together, such as by co-molding, flame lamination or adhesive bonding. Then, the components forming the central mattress section  12 , first and second end walls  14 ,  16 , first and second side walls  20 ,  22 , and first, second, third, fourth sidewall extensions  24 ,  26 ,  28 ,  30  are cut to desired size. These components are then connected by various hinges  40 ,  42 ,  44  to form the size-convertible mattress. 
     The sidewall extensions  24 ,  26 ,  28 ,  30  may be formed with one or more voids  60  therein. Voids  60  are suitable for receiving toys or accessories (not shown) when the size convertible mattress is in its crib configuration  10  ( FIG. 1 ). Such voids  60  do not detract from body-supporting characteristics of the sidewall extensions when the mattress is in its twin bed configuration  70  ( FIG. 4 ). 
     Referring next to  FIGS. 7-9 , a second embodiment of a size-convertible mattress according to the invention has a crib configuration  110  in which a central mattress section  112  is surrounded by upstanding end walls  114 ,  116  and side walls  120 ,  122 . In its crib configuration  110  the mattress of this second embodiment may have outer periphery dimensions comparable to a standard crib mattress, such as about 27 inches by 52 inches (69 cm by 131 cm). 
     In the second mattress embodiment ( FIG. 7 ), the end walls may have dimensions of about 18 inches in height, 27 inches in length and 6 inches in width. The side walls may have dimensions of about 6 inches in height, 51 inches in length and 6 inches in width. The sidewall extensions may have dimension of about 6 inches in height, 20 inches in length and 6 inches in width 
     The size convertible mattress of the second embodiment may be converted from its crib configuration  110  to a twin mattress configuration  170  ( FIG. 9 ) upon separating the first and second end walls  114 ,  116  and side walls  120 ,  122  and reattaching them to side surfaces of the central mattress section  112  in a manner as described herein. In the crib configuration  110  ( FIG. 7 ), the side walls  120 ,  122  are removably joined to the planar top surface of the central mattress section  112  with fasteners  50 , such as hook and loop strips (sometimes referred to as Velcro® fasteners). In the crib configuration  110  ( FIG. 7 ), the end walls  114 ,  116  are removably joined to end portions of the side walls  120 ,  122  and sidewall extensions  124 ,  126 ,  128 ,  130  with fasteners  50 , such as hook and loop strips. Fastener connections are similar to those used in the first embodiment described with reference to  FIGS. 1-6 . 
     The first and second end walls  114 ,  116  have tethers  100  formed at their bottom corners. For example, a first portion of a tether  100  is joined or attached to an outer surface of the first end wall  114 , and a second portion of a tether  100  is joined or attached to a bottom generally planar surface of the central mattress section  112 . See  FIG. 7 . Possible materials to form the tethers  100  include fabrics, laminates and elastics. Woven nylon or cotton that includes elastomeric stretch yarns is one example of a fabric with stretch that may be used. Resilient rubber or latex sheeting are examples elastics that may be used. The tether material may be coated with moisture-resitant barrier-coatings. The tethers  100  may be joined to the surfaces of the components forming the mattress with adhesive, or by flame lamination or by stitching or by other known attachment means. 
     As shown in  FIG. 8 , the second end wall  116  may separated from the first and second side walls  120 ,  122  and second and fourth sidewall extensions  126 ,  130  and turned 90 degrees (rotated) in the direction of arrow  134  so as to lay flat. Upon rotating the second end wall  116 , the fasteners  50  holding the second end wall to end surfaces of the first and second side walls  120 ,  122  and second and fourth sidewall extensions  126 ,  130  are separated from one another. When fully opened, the inner side surface of the second end wall  116  forms a plane or substantially forms a plane with the planar top surface of the central mattress section  112  (See  FIG. 9 ). The tethers  100  hold the second end wall  116  in proximity to or adjacent to the central mattress section  112  as the mattress is being converted or reconfigured. 
     Similarly, the first end wall  114  may be separated from the first and second side walls  120 ,  122  and first and third sidewall extensions  124 ,  128  and turned 90 degrees (rotated) so as to lay flat. Upon rotating the first end wall  114 , the fasteners  50  holding the first end wall to end surfaces of the first and second side walls  120 ,  122  and first and third sidewall extensions  124 ,  128  are separated from one another. When fully opened, the inner side surface of the first end wall  114  forms a plane or substantially forms a plane with the planar top surface of the central mattress section  112 . The tethers  100  hold the first end wall  114  in proximity to or adjacent to the central mattress section  112  as the mattress is being converted or reconfigured. 
     Still referring to  FIG. 8 , the first side wall  120  may be separated from the central mattress section  112  and turned 90 degrees (rotated) in the direction of arrow  136  and folded down so as to lay flat. Upon rotating the first side wall  120 , the fasteners  50  holding one lengthwise side surface of the first side wall  120  to the top planar surface of the central mattress section  112  are separated from one another. In addition, the second side wall  122  may be turned 90 degrees (rotated) in the direction of arrow  136  and folded down so as to lay flat. Upon rotating the second side wall  122 , the fasteners  50  holding one lengthwise side surface of the second side wall  122  to the top planar surface of the central mattress section  112  are separated from one another. The tethers  102  hold the first and second side walls  120 ,  122  in proximity to or adjacent to the central mattress section  112  as the mattress is being converted or reconfigured. 
     When the second embodiment of the mattress is in the crib configuration  110 , the first and second sidewall extensions  124 ,  126  are held in contact with a side surface of the first side wall  120  with fasteners  50  (such as hook and loop fasteners). The longitudinal axes of the first and second sidewall extensions  124 ,  126  are generally in parallel with the longitudinal axis of the first side wall  120 . Once the first side wall  120  is in its open position, fasteners  50  may be released and first and second sidewall extensions  124 ,  126  may be rotated in the direction of arrows  138  ( FIG. 8 ) about hinges  144  to open positions in which the first and second sidewall extensions  124 ,  126  are axially aligned with the first side wall  120 . Alternatively, the first and second sidewall extensions  124 ,  126 , may be rotated when the first side wall  120  is in its upright position, but after the first and second end walls  114 ,  116  have been rotated to their open positions. See  FIGS. 8 and 9 . Similarly, the third and fourth sidewall extensions  128 ,  130  may be rotated about hinges  144  to open positions in which the third and fourth sidewall extensions  128 ,  130  are axially aligned with the second side wall  122 . 
     In the twin mattress configuration ( FIG. 9 ), the first and second end walls  114 ,  116  are aligned with surfaces generally planar with the generally planar top surface of the central mattress section  112 . In addition, the first and second side walls  120 ,  122  are aligned with surfaces generally planar with the generally planar top surface of the central mattress section  112 . Moreover, the first, second, third and fourth sidewall extensions  124 ,  126 ,  128 ,  130  are unfolded down and axially aligned with the first and second side walls  120 ,  122 . As so rotated and unfolded, the central mattress section  112 , first and second end walls  114 ,  116 , first and second side walls  120 ,  122  and first, second, third and fourth sidewall extensions  124 ,  126 ,  128 ,  130  together form a generally planar surface of a size of a twin bed mattress configuration  170  ( FIG. 9 ). Fasteners  50  (not shown) may be provided at facing surfaces to hold the various components together in the twin bed mattress configuration  170  ( FIG. 9 ). 
     In the twin bed mattress configuration  170 , the mattress may have an outer periphery dimension comparable to a standard twin mattress, such as about 39 inches by 75 inches (99 cm by 191 cm). The twin bed mattress configuration  170  preferably has a thickness in the range of 6 to 18 inches (15 cm to 46 cm), more preferably about 6 inches (15 cm). 
     The size-convertible mattress may be folded back from the twin mattress configuration  170  ( FIG. 9 ) to the crib mattress configuration  110  ( FIG. 7 ) by releasing any fasteners between components and reassembling the end walls  114 ,  116 , side walls  120 ,  122  and sidewall extensions  124 ,  126 ,  128  and  130  in upright configurations, such as by turning or rotating by 90 degrees. The components may be re-fastened together in the crib configuration  110 . 
     The invention has been illustrated by detailed description and examples of the preferred embodiments. Various changes in form and detail will be within the skill of persons skilled in the art. Therefore, the invention must be measured by the claims and not by the description of the examples or the preferred embodiments.