Mattress structure having a foam mattress core

BACKGROUND SUMMARY OF THE INVENTION

This application is a continuation in-part of co-pending U.S. application Ser. No. 08/565/409, filed Nov. 30, 1995 now U.S. Pat. NO. 5,669,757.

The present invention relates to mattress structures and particularly to a mattress structure having a foam mattress core. The mattress structure may be configured as a stand-alone unit for use on any deck for a bed or the mattress structure may be configured for use with an associated base. More particularly, the present invention relates to a mattress structure having a foam core that is shaped and configured to provide support and firmness characteristics similar to those provided by mattresses having air bladders.

It is well know to provide foam support pads or mattresses for supporting a user reclining on the pad. For example, U.S. Pat. Nos 4,879,776; 5,038,433; 5,077,849; 5,111,542; and 5,172,439, all to Farley, disclose mattress overlays and pads for supporting a user. In addition, U.S. Pat. Nos. 4,449,261 to Magnusson and 4,991,244 to Walker disclose mattress borders for receiving core mattresses and U.S. Pat. Nos. 5,105,488 to Hutchinson et al.; 4,803,744 to Peck et al.; and 4,424,600 and 4,435,864 to Callaway disclose supporting surfaces having selectively adjustable firmness. Finally, U.S. patent application Ser. No. 08/565,409 to Washburn et al. filed Nov. 30, 1995 and assigned to an affiliate of the assignee of the present invention, the specification of which is herein incorporated by reference, discloses a mattress kit and mattresses constructed therefrom that can include a plurality foam core elements

What is needed is a mattress structure having a foam core provided with longitudinally spaced and transversely extending zones providing the support and firmness characteristics typically provided by a mattress including a core having longitudinally spaced-apart air bladders. In addition, users would appreciate such a mattress having a foam mattress core of unitary construction and which is compatible with a bed having an articulating deck. Such a mattress should also include a mechanism for minimizing the sheer forces directed against the user when the bed carrying the mattress articulates.

According to the present invention, an elongated mattress core for a mattress structure is provided. The mattress core includes a foam core. The foam core has an upwardly-facing top surface, a bottom surface spaced apart from the top surface, and first and second spaced-apart elongated sides connecting the top and bottom surfaces.

The foam core is formed to include a plurality of longitudinally spaced-apart transverse slits extending downwardly from the top surface. Each slit terminates at a lower end which is spaced apart from the bottom surface by a first distance. In addition, each slit extends transversely from a first slit end spaced apart from the first side of the foam core to a second slit end spaced apart from the second side of the foam core. Each adjacent pair of slits defines a foam column. Thus, the foam core has a plurality of longitudinally spaced apart and transversely extending foam columns, each foam column having a pair of generally vertical column side walls defining the slits.

In preferred embodiments, the mattress structure includes a mattress cover defining an interior region and a foam core received in the interior region. A shear layer made from a material having a low coefficient of friction preferably covers the top and sides of the foam core and is positioned between the foam core and the mattress cover so that the mattress cover can slide relative to the foam core. Thus, if the mattress structure is used on a bed having an articulating deck, the mattress cover can slide relative to the foam core as the deck articulates to minimize the shear forces acting between the mattress cover and the user during articulation of the deck and mattress structure and instead expend those shear forces by having the mattress cover slide relative to the foam core.

The foam core also includes a plurality of longitudinally spaced apart and transversely extending foam columns. Each foam column includes a top, a bottom, and generally vertically extending and transversely extending side walls connecting the top and the bottom. The side walls of adjacent foam columns cooperate to define a plurality of longitudinally spaced-apart and transversely extending slits.

The side walls of each foam column include a low-friction coating so that each column can compress and decompress without being hindered by drag forces resulting from frictional engagement with adjacent foam columns. Preferably, the low-friction coating is a fabric or material having a low coefficient of friction which is received by the slit defined by the adjacent side walls of adjacent foam columns. Thus, the unitary foam core is in effect provided with longitudinally spaced-apart zones of foam that operate independently to provide the mattress structure with longitudinal zones similar to the zones that can be provided by air bladders.

As mentioned above, the foam core is of unitary construction. In addition, however, the foam core can be configured so that the firmness and support characteristics of each foam column is individually selected prior to manufacture. Individually selecting the support and firmness characteristics of each foam column of the mattress structure allows the mattress structure to provide support and firmness characteristics that vary along the length of the sleeping surface of the mattress structure. Having varied support and firmness characteristics allows the mattress structure to achieve a profile along the length of the mattress structure of support and firmness characteristics similar to the support and firmness characteristics that can be provided by a mattress structure having a plurality of air bladders.

The mattress structure in accordance with the present invention can be provided in a “stand-alone” first embodiment for use on any bed deck or other generally horizontal surface or a second embodiment including a separate base for supporting the mattress. With each embodiment, the foam core includes a foam frame made from relatively stiff foam bonded to a perimeter defined by the plurality of foam columns. In the first embodiment, the entire frame is attached to the plurality of columns. In the second embodiment, the frame includes an upper portion attached to the plurality of columns and a lower portion attached to the base to form a base frame so that the second embodiment of the mattress structure provides the advantages of a step deck and a mattress for a step deck as described in U.S. patent application Ser. Nos. 08/511,546 to Kramer et al. and 08/511,547 to Weismiller et al., both filed on Aug. 4, 1995 and both assigned to an affiliate of the assignee of the present invention.

Additional objects, features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figures in which:

FIG. 1

is a perspective view of a “stand-alone” mattress structure in accordance with the present invention showing a mattress cover including a bottom cover having handles and a top cover connected to the bottom view of the zipper;

FIG. 2

is an exploded perspective view of the mattress structure of

FIG. 1

showing a mattress core received between the top cover and the bottom cover of the mattress cover, the bottom cover having a portion broken away to reveal a foam bottom, the mattress core comprising a foam core including a core frame having foam side members and foam end members made from relatively stiff foam and defining a central opening therein containing a plurality of longitudinally spaced apart and transversely extending foam columns attached to the core frame so that the foam core is of unitary construction, the foam columns defining a plurality of longitudinally spaced-apart and transversely extending slits receiving shear panels made from slip fabric sandwiched between the foam columns to permit independent movement of each foam column so that each foam column compresses and decompresses without interference due to drag forces resulting from frictional engagement against adjacent foam columns, and a shear layer wrapped around the foam core and positioned to lie between the foam core and the top cover of the mattress cover so that the mattress cover can slide relative to the foam core;

FIG. 3

is a top plan view of the mattress structure of

FIG. 1

with portions broken away showing one of the foam side members of the foam frame, foam columns attached to the side member, the foam columns defining transverse slits therebetween, slots (in phantom) cooperating with the transverse slits to define openings extending from the top surface of the foam core to the bottom surface of the foam core, shear panels made from slip fabric sandwiched between the foam columns and extending therebetween across the top of the foam columns, the shear layer positioned to lie on top of the shear panels and on top of the foam core, and the top cover of the mattress cover covering the mattress core;

FIG. 4

is a sectional view taken along line

4

—

4

of

FIG. 3

showing the mattress received in the base cover and including foam columns defining a head zone, a shoulder zone, a seat zone, a thigh zone, and a foot zone, slit fabric including tabs received in the slots formed between the foam columns and folding against the bottom surface of the foam core, and each foam column in the foot zone including an upper column portion made from relatively soft foam to minimize the interface pressure against the heal of the user and a lower column portion beneath the upper column portion, the lower column portion being made from relatively stiff foam to provide additional support;

FIG. 5

is an exploded perspective view of the underside of the foam core of the stand-alone mattress showing the shear panel made from slip fabric at various stages of installation, each shear panel including first and second tabs received by the slots formed between the foam columns of the foam core, first and second side panels received by the slits formed between the foam columns and separating adjacent side walls of adjacent foam columns, and a top panel covering a top surface of the foam column, the first and second tabs folding underneath and against the bottom surface of the foam core and being connected to one another by I-shaped connectors to hold each shear panel to its respective foam column;

FIG. 6

is a sectional view taken along line

6

—

6

of

FIG. 3

showing first and second side panels of the shear panel positioned in the slit defined between adjacent side walls of adjacent foam columns, the adjacent foam columns being attached to one another beneath the slit, first and second tabs of the shear panels folded against the bottom surface of the foam core and connected by one of the I-shaped connectors penetrating both of the first and second tabs, and a shallow slit extending downwardly from the top surface of the foam column to adjust the surface tension across the foam column and thereby “fine-tune” the firmness and support characteristics of the foam column;

FIG. 7

is a sectional view taken along line

7

—

7

of

FIG. 3

showing the foam end member on the head end of the foam core including an upper foam end member having a top surface adjacent to the top surfaces of the foam columns and a lower foam end member having a bottom surface adjacent to the bottom surfaces of the foam columns, two foam columns adjacent to the foam end member, slip fabric including a shear panel wrapped around the foam end member and the foam column adjacent to the foam end member, slots between the foam columns cooperating with slits to define openings extending from the top surface of the foam core through to the bottom surface of the foam core, and shear panels including first and second side panels and tabs extending through the slits, the tabs extending through the slots and being folded against the bottom surface of the foam core;

FIG. 8

is a perspective view of a second embodiment of a mattress structure in accordance with the present invention showing a mattress cover including a bottom cover having handles and defining a base and a top cover connected to the bottom cover by a zipper so that the mattress structure is ready for use by a user;

FIG. 9

is an exploded perspective view of the mattress structure of

FIG. 8

showing a mattress core received between the top cover and the bottom cover of the mattress cover, the bottom cover of the mattress cover covering a base, the base including a perimetral rectangular base frame defining a central opening therein and receiving a foam bottom therein, a storage cover above the base used for storing the mattress core, a foam core having a rectangular core frame defining a central opening therein receiving a plurality of foam columns, a shear layer for covering the foam core, and the top cover of the mattress cover having a zipper with meets with a zipper on the top of the bottom cover to attach the top and bottom covers of the mattress cover together;

FIG. 10

is a sectional view taken along line

10

—

10

of

FIG. 9

showing the mattress core received in the base and including foam columns defining a head zone, a shoulder zone, a seat zone, a thigh zone, and a foot zone, slip fabric including tabs received in the slots formed between the foam columns and folding against the bottom surface of the foam core, and each foam column in the foot zone including an upper column portion made from relatively soft foam to minimize the interface pressure against the heel of the user and a lower column portion beneath the upper column portion, the lower column portion being made from relatively stiff foam to provide additional support; and

FIG. 11

is a view of the mattress core of

FIG. 8

sandwiched between the top cover of the mattress cover and the storage cover, the storage cover including a perimetral zipper that meets with the zipper on the mattress cover to attach the storage cover to the top cover of the mattress cover for use in storing the foam core.

DETAILED DESCRIPTION OF THE DRAWINGS

A first embodiment of an illustrative mattress structure

50

in accordance with the present invention is shown in FIGS.

1

-

7

and an illustrative second embodiment of a mattress structure

250

is shown in

FIGS. 8-11

. Illustrative first embodiment of mattress structure

50

in accordance with the present invention includes a mattress cover

52

having a top cover

54

and a bottom cover

58

connected to top cover

54

by a zipper

60

. Top cover

54

includes an upwardly-facing sleeping surface

56

above which a user will rest. Handles

62

can be provided on either top cover

54

or bottom cover

58

as shown in

FIG. 1

or on any portion of top or bottom covers

54

,

58

as desired to facilitate transport of mattress structure

50

.

Top and bottom covers

54

,

58

of mattress cover

52

cooperate to define an interior region

64

of mattress cover

52

as shown in FIG.

2

. Interior region

64

of mattress cover

52

receives a mattress core

76

including a foam core

66

, shear panels

94

carried by foam core

66

, and a shear layer

68

as shown in FIG.

2

. In preferred embodiments, foam core

66

is made from a foam rubber material such as urethane foam, although any suitable material providing similar support and firmness characteristics to those described below for foam core

66

can be used without exceeding the scope of the invention as presently perceived.

Shear layer

68

includes a top panel

60

, downwardly-extending sides

72

appended to the perimeter of top panel

70

, and a fitted portion

74

appended to sides

72

and extending at least partially beneath top panel

70

. Top panel

70

cooperates with sides

72

and fitted portion

74

of shear layer

68

to define an interior region (not shown) which receives foam core

66

. Fitted portion

74

includes edge

78

defining an opening (not shown) beneath top panel

70

allowing for movement of foam core

66

into and out of the interior region of shear layer

68

. Preferably, fitted portion

74

is provided with an elastic band (not shown), a drawstring (not shown), or other structure drawing the opening of fitted portion

74

closed to facilitate wrapping shear layer

68

snugly around foam core

66

.

Mattress structure

50

may be used with a bed or table including an articulating deck (not shown) having pivoting head, shoulder, seat, thigh, or leg sections. As portions of mattress structure

50

bend during articulation of the deck, the movement of mattress structure

50

will cause mattress structure

50

to slide relative to the user resting on sleeping surface

56

. If the mattress cover were to slide relative to the user and thus rub against the user during articulation of the deck, this rubbing and sliding could irritate the user's skin.

Shear layer

68

is preferably made from material having a low coefficient of friction such as nylon or “parachute” material, or any other suitable material that will allow top cover

54

of mattress cover

52

to slide relative to foam core

66

. Top cover

54

will frictionally engage the user lying on sleeping surface

56

so that when mattress core

76

includes shear layer

68

, top cover

54

will tend to move with the user rather than moving with foam core

66

during articulation of the deck. Thus, use of shear layer

68

will minimize the rubbing of mattress structure

50

against the user during articulation of the deck.

Foam core

66

includes a generally rectangular foam core frame

80

having an elongated foam first side member

82

, an elongated foam second side member

84

spaced apart from first side member

82

, a foam end member

86

abutting first and second side members

82

,

84

on a head end

46

of foam core

66

, and a foam end member

88

abutting first and second side members

82

,

84

on a foot end

48

of foam core

66

as shown in FIG.

2

. Core frame

80

defines a generally rectangular central opening

90

above which the user will rest.

A plurality of foam columns

92

is received in central opening

90

as shown in FIG.

2

and foam columns

92

are attached to core frame

80

. Each foam column

92

extends transversely from a first end

96

of foam column

92

abutting first side member

82

to a second end

98

of foam column

92

abutting second side member

84

. Preferably, first end

96

of each foam column

92

is attached to first side member

82

and second end

98

of each foam column

92

is attached to second side member

94

.

Each foam column

92

includes first and second spaced-apart side walls

100

as shown best in

FIGS. 3 and 4

. Side walls

100

extend transversely between first and second side members

82

,

84

of core frame

80

. Side walls

100

also extend generally vertically from a top surface

110

to a bottom surface

112

. In addition, each foam column

92

includes a top portion

114

and a bottom portion

116

. In preferred embodiments, side walls

100

adjacent to bottom portion

116

of each foam column

92

are attached to bottom portions

116

of adjacent side walls

100

of both adjacent foam columns

92

so that foam core

66

including core frame

80

and foam columns

92

is of unitary construction.

Top portion

114

of each side wall

100

of each foam column

92

extends downwardly from top surface

110

by a first distance

118

as shown best in

FIGS. 6 and 7

. Bottom portion

116

extends upwardly from bottom surface

112

a second distance

120

to meet top portion

114

at an interface

122

. In preferred embodiments, bottom portion

116

of each side wall

100

is integrally appended to bottom portion

116

of each abutting side wall

100

. Preferably, the bottom portions

116

of abutting side walls

100

are joined by R.F. welding, although any suitable method for joining foam columns

92

such as gluing side walls

100

together, attaching adjacent side walls

100

using plastic rivets or other fastening devices (not shown), or starting with a unitary block of foam and sculpting the block to include a plurality of longitudinally spaced-apart and transversely extending slits defining foam columns therebetween, can be used without exceeding the scope of the invention as presently perceived.

Longitudinally spaced-apart foam columns

92

define a plurality of zones along foam core

66

which provide support and firmness characteristics for a user carried on sleeping surface

56

of mattress structure

50

as shown in

FIG. 4

Illustratively, foam columns

92

define a head zone

146

adjacent to head end

46

of foam core

66

, a shoulder zone

148

adjacent to head zone

146

, a set zone

150

adjacent to shoulder zone

148

, a thigh zone

152

adjacent to seat zone

150

, and a foot zone

154

adjacent to thigh zone

152

and foot end

48

of foam core

66

. Foot zone

154

of illustrative and preferred foam core

66

includes three foam columns

92

, each of which include an upper column portion

156

and a lower column portion

158

as shown best in FIG.

4

. Likewise, illustrative and preferred frame end members

86

,

88

each include an upper end member

160

and a lower end member

162

.

The firmness and support characteristics provided by each foam column

92

depend in part upon the indention load deflection (ILD) of the foam from which each foam column

92

is made. The ILD is a well-known industry-accepted index indicating the “firmness” of materials such as urethane foam and other foam rubber materials. The ILD indicates the amount of deflection exhibited by a block of foam when subjected to a specified force distributed over a specified area of foam. It is within the scope of the invention as presently perceived to provide foam core

66

wherein each of the plurality of foam columns

92

has the same ILD or to provide foam core

66

wherein the ILD of at least one foam column

92

is different from the ILD of at least one other foam column

92

. For example, preferred foam core

66

can be constructed so that foam columns

92

of head zone

146

have an ILD of 11, foam columns

92

of should zone

148

have an ILD of 11, foam columns

92

of seat zone

150

have an ILD of 17, foam columns

92

of thigh zone

152

have an ILD of 11, foot zone

154

lower column portions

158

have an ILD of 11, and foot zone

154

upper column portions

156

have an ILD of 7. Although it is preferred that foam columns

92

be made from foam having ILDs as described above, foam columns

92

can be made from foam rubber portions of various ILDs to provide the desired support and firmness characteristics for mattress structure

50

. For example, it is sometimes desirable to provide foam columns

92

made from foam having an ILD of 17 in shoulder zone

148

to provide additional firmness and support characteristics to mattress structure

50

adjacent to shoulder zone

148

.

Foot zone

154

is provided with upper and lower column portions

156

,

158

to relieve interface pressure against the heel of the user while also providing sufficient support for the user's feet. This is achieved by providing upper column portions

156

made from foam having a relatively low ILD and relatively plush support and firmness characteristics, and lower column portions

158

made from foam having a higher ILD to provide additional firmness and support.

It can also be seen that head end and foot end members

86

,

88

are each provided with upper and lower end members

160

,

162

to achieve a similar result. Each upper end member

86

of illustrative and preferred foam core

66

is made from foam having an ILD matching the ILD of the adjacent foam column

92

. For example, upper end member

160

of head end foam member

86

of illustrative foam core

66

is made from foam having an ILD of 11 just as foam columns

92

of head zone

46

are made from foam having an ILD of 11. Similarly, upper end member

160

of foot end member

88

of illustrative form core

66

is made from foam having an ILD of 7, just as upper column portions

156

of foam columns

92

of foot zone

154

are made from foam having an ILD of 7. However, lower end members

162

are preferably made from urethane foam having an ILD of 41 which provides significantly greater support and firmness characteristics than upper end members

160

. Thus, by forming head end and foot end members

86

,

88

from upper end members

160

made from foam having ILDs similar to those of the adjacent foam columns

92

and lower end members

162

providing significantly greater support and firmness characteristics, head end and foot end members

84

,

86

provide support and firmness characteristics to a user lying on sleeping surface

56

that are substantially similar to other portions of sleeping surface

56

while also providing additional support to a user entering or exiting mattress structure

50

from either head end

46

or foot end

48

.

First and second side members

82

,

84

include longitudinally extending upper side member

164

and longitudinally extending lower side member

166

as shown in

FIGS. 1 and 5

. In preferred mattress structure

50

, upper and lower side member

164

,

166

of foam core

66

are each made from foam having an ILD of 41 to provide additional support and firmness characteristics along sides of mattress structure

50

. The additional support and firmness characteristics along side of mattress structure

50

assist users entering or exiting sleeping surface

56

along the sides of mattress structure

50

. If desired, first and second side members

82

,

84

can each be unitary members.

Although upper and lower side members

164

,

166

of illustrative and preferred core frame

80

of foam core

66

are both made from urethane foam having an ILD of 41, it is within the scope of the invention as is presently perceived to provide upper and lower side members

164

,

166

providing different support and firmness characteristics. For example, upper side member

164

could be made from foam having an ILD of 17 and lower side member

166

could be made from foam having an ILD of 41 so that aide members

82

,

84

of core frame

80

provide additional support to users egressing or ingressing onto sleeping surface

56

while also providing a user on sleeping surface with support and firmness characteristics that are similar to the support and firmness characteristics of other portions of sleeping surface

56

. Thus, the foam materials and the firmness and support characteristics resulting therefrom can be varied without exceeding the scope of the invention as presently perceived.

Each side wall

100

adjacent to top portion

114

of side wall

100

cooperates with top portion

114

of abutting side wall

100

to define a transversely-extending slit

130

. Side walls

100

of the plurality of foam columns

92

thus cooperate to define a plurality of longitudinally spaced-apart and transversely-extending slits

130

as shown in

FIGS. 2-4

,

6

, and

7

. Each slit

130

has an upper end adjacent to top surface

110

of foam core

66

and a lower end

130

adjacent to interface

122

between top and bottom portions

114

,

116

. In addition, each side wall

100

adjacent to bottom portion

116

of side wall

100

cooperates with bottom portion

116

of abutting side wall

100

to define a transversely extending slot

132

beneath slit

130

. Side walls

100

of the plurality of foam columns

92

thus cooperate to define a plurality of longitudinally spaced-apart and transversely-extending slots

132

, each slot

132

being beneath a slit

130

as shown best in

FIGS. 3

,

5

, and

7

. Illustratively, each slot

132

is associated with a slit

130

which is defined by the same adjacent side walls

100

as slot

132

. Each slot

132

includes a first end

138

spaced apart from the first end

134

of its associated slit

130

and a second end

140

spaced apart from the second end

136

of its associated slit

130

so that illustrative slots

132

do not extend the full transverse length of slits

130

.

In illustrative and preferred foam core

66

, three transversely spaced-apart slots

132

are associated with each slit

130

as shown in FIG.

3

. Slots

132

are transversely spaced apart from one another and are transversely spaced apart from first side member

82

and second side member

84

of core frame

80

. In preferred embodiments, bottom portions

116

of adjacent side walls

100

are attached to one another along portions of bottom portion

116

between slots

132

.

As described above, slits

130

extend downwardly from top surface

110

of foam core

66

as shown best in

FIGS. 6 and 7

. Slots

132

extend upwardly from bottom surface

112

and cooperate with slits

130

to define openings extending from top surface

110

to bottom surface

112

of foam core

66

as shown best in FIG.

7

.

If desired, each foam column

92

can also be formed to include a shallow slit

172

as shown best in

FIGS. 4

,

6

, and

7

. Each shallow slit

172

extends downwardly from top surface

110

to a lower end

174

of shallow slit

172

, the lower end

174

being spaced apart from bottom surface

112

a distance

176

. Typically, distance

176

is greater than distance

120

between lower end

142

of slit

130

and bottom surface

112

of foam core

66

. Thus, slit

130

extends downwardly from top surface

110

into foam core

66

a distance greater than shallow slit

172

extends from top surface

110

into foam core

66

.

Shallow slits

172

are formed in foam columns

92

to “fine-tune” the support and firmness characteristics provided by each foam column

92

. Shallow slits

172

operate to relieve surface tension formed across top surface

110

of each foam column

92

. Shallow slit

172

relieves surface tension from top surface

110

of foam column

92

and allows foam column

92

to provide columnar support from below instead of “hamocking” and providing sideways support through surface tension in top surface

110

.

As described above, support and firmness characteristics provided by each zone

146

,

148

,

150

,

152

,

154

of foam core

66

can be altered by making foam columns

92

of each zone

146

,

148

,

150

,

152

,

154

from foam having an ILD that is different from the ILD of foam columns

92

of other of zones

146

,

148

,

150

,

152

,

154

. In addition, the support and firmness characteristics provided by foam columns

92

can be further adjusted by forming foam columns

92

to include shallow slits

172

. Illustrative and preferred foam core

66

is formed so that each foam column

92

is formed with a shallow slit

172

and so that a distance

176

between a lower end

174

of shallow slit

172

and bottom surface

112

of foam core

66

is equivalent for each shallow slit

172

within each zone

146

,

148

,

150

,

152

,

154

.

However, as shown best in

FIG. 4

, distance

176

for shallow slits

172

varies from zone to zone

146

,

148

,

150

,

152

,

154

. For example, distance

176

for shallow slits

172

of seat zone

150

is greater than distance

176

for shallow slits

172

of thigh zone

152

. Thus, while the support and firmness characteristics provided by foam columns

92

of seat zone

150

are adjusted slightly by reducing the hamocking effect in seat zone

150

, the support and firmness characteristics provided by foam columns

92

of thigh zone

152

are adjusted even further by providing shallow slits

172

that extend deeper into foam core

66

from top surface

110

to provide even further adjustment of thigh zone

152

so that thigh zone

152

provides even softer, plusher support and firmness characteristics than would otherwise be provided.

Side walls

100

of foam columns

92

are provided with an “anti-friction” shear coating so that each top surface

110

of each foam column

92

can move upwardly and downwardly relative to bottom surface

112

of foam core

66

independently of the upward and downward movement of top surfaces

110

of adjacent foam columns

92

as each foam column

92

compresses and decompresses relative to adjacent foam columns

92

. Producing foam core

66

without the shear coating on side walls

100

would limit the independent movement of each foam column

92

. Instead, each foam column

92

would interact with each adjacent foam column

92

as each side wall

100

frictionally engages each adjacent side wall

100

. This interaction due to the frictional engagement of abutting side walls

100

would significantly reduce the ability of adjacent foam columns

92

to compress and decompress independently of one another, thus reducing the ability of mattress structure

50

to provide support and firmness characteristics similar to those provided by mattress structures having longitudinally spaced-apart air bladders.

In preferred embodiments, the “anti-friction” shear coating is provided by shear panels

94

of mattress core

76

as shown best in FIG.

5

. Each shear panel

94

includes a generally horizontal top panel

186

having two spaced-apart side edges, a first side panel

184

appended to the first edge of top panel

186

and extending downwardly therefrom, a first tab

182

appended to first side panel

184

and extending downwardly therefrom, a second side panel

188

appended to the second edge of top panel

186

and extending downwardly therefrom, second side panel

188

being spaced apart from first side panel

184

, and a second tab

190

appended to second side panel

188

and extending downwardly therefrom.

First and second side panels

184

,

188

are received in slits

130

as shown best in

FIGS. 5-7

to separate the abutting side walls

100

so that adjacent foam columns

92

are free to compress and decompress without interference due to frictional engagement with side walls

100

of adjacent foam columns

92

. First and second tabs

182

,

190

are received in slots

132

and have exposed ends

192

that extend therethrough as shown best in

FIGS. 5 and 7

. In preferred embodiments, exposed end

192

of first tab

182

is attached to exposed end

192

of second tab

190

to connect shear panel

94

to foam core

66

. Although the preferred installation of shear panel

94

includes joining exposed ends

192

of first and second tabs

182

,

190

to hold shear panel

182

to form core

66

, other methods of connecting shear panel

94

to foam core

66

can be employed without exceeding the scope of the invention that is presently perceived. For example, first and second side panels

184

,

188

can each be directly attached to a side wall

100

of foam columns

192

.

In preferred embodiments, exposed ends

192

of first and second tabs

182

,

188

are connected to one another using I-shaped connectors

194

as shown in

FIGS. 5-7

. Each I-shaped connector

194

includes an upper bar

196

, a lower bar

198

, and a connecting post