CA2112895C

CA2112895C - Multilayer mattress

Info

Publication number: CA2112895C
Application number: CA002112895A
Authority: CA
Inventors: Jack Schwartz
Original assignee: ANATA SYSTEMS INTERNATIONAL Inc
Current assignee: ANATA SYSTEMS INTERNATIONAL Inc
Priority date: 1991-08-20
Filing date: 1992-08-11
Publication date: 1998-08-04
Anticipated expiration: 2012-08-11
Also published as: AU2438692A; EP0599922A1; AU690889B2; CA2117000A1; US5513402A; US5819349A; GB2313051B; AU1703395A; WO1993003654A1; GB9717289D0; ATE134114T1; WO1995022272A1; BR9207151A; NO950430D0; NO950430L; CA2112895A1; DE69208364T2; JPH07509376A; GB2313051A; ES2086133T3

Abstract

A mattress system is disclosed which permits the, or each, user to select readily the mattress firmness either for a single bed, or independently for each half of a bed to be used by two people. Regardless of the firmness chosen, the overall thickness is maintained constant. The mattress (11) comprises a plurality of foam mattress elements (12-16, 22-26), of different firmnesses together with a substantially rigid core (17, 27) element; alteration of the sequence in the set changes the firmness. A two person mattress includes two sets of mattress elements. Additionally, a torso board can be included to provide a localized firmer surface.
The system also provides an essentially smooth transition between two sets when used, for example, in a double bed.

Description

W093/~3654 21i 2 ~ 9 5 PCI/CA92/0034B

MUI.TILAYER ~TTRESS ~ -This invention is concerned with a mattress and a combination system including the mattress for use on a bed frame which will provide the user, or users, with a ~:
choice of mattress firmness without disturbing the overall height of the sleeping surface from the floor. ~:

In the following discussion two terms are used to~'-have meanings somewhat different to those commonly a~tributed to them. ~-By a "single" bed, mattress, or the like, is meant a unit of a size commonly used by o~e person; thus, ~.
it can range upwardly from a crib or child' s bed, at least to the size known in North America as twin ~that is, up to about 1 meter in width and about 1.8 meters in length). ~;~

- By a "double" bed, mattress, or the :like, is ~-~
meant a unit of a size commonly used by two persons; thus, it can range upwardly from the size known in North America as double ~abQut 1.8 meters in width and about 2.1 meters in length).

Generally speaking, the hardness, or firmness, of a conventional bed comprising a mattress supported by a ~:
base is determined by the choice of materials made during the cons~ruction of each of the mattress and the base. ~;
Consequently, beds are available in which the firmness can vary at different p~ints within a particular bed, and in which th~ overall firmness varies between separate beds.
However, the only choice of flrmness which a user can make with such a conuentional be~ or mattress is made when the bed or mattress is purchased. Thereafter, the user has lit~le further choice, other than to replace the item.
Choice on purchase is apparently simple, and is usually a matter of trial and error. Generally, the choice is made ~:

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WO 93/03~54 PCr/CAg2/0034 by sittirlg or lying briefly on the mattress, for example in a bedding store. This is not an adequate or very reliable test method. A further significant prsblem can arise if either a need is encountered to change the firmness of an existing bed (either temporarily or permanently) r or if two - persons using a double bed require radically different firmnesses. For example, one person may require a very firm support for orthopaedic reasons, whilst the other may find such a level of firmness uncomfortable to the point that sleep is not possible.

There are also problems of deflection transmission sideways:across a bed, especially if one user is of sig~ificantly different weight to thè other.
~ ~, This invention seek5 to mitigate and:to overcome ~-these problems by providing ~ mattress for use on a bed .-frame support system in~which the firmness can be chosen at ..
will, even on a~:dai~ly:basis. :~Consequently, this invent~ion seeks to provide a mattress:for a single person in which :the hardness can~:~ be~ changed, either temporarily or permanen~ly, in response to a perceived:need.

Additionally, a :mattress according ~to :this~
invention can:~be maintained at a given level:of firmness~on:~
an on-going basis: over~ a pe:riod of time. C~onsequently, ;
such a mattress is~ not subject to the loss of:~firmness : encountered with a c:onventional~mattress:~after an extende~d period of use. Further, this invention seeks to provide a mattress for two people which permits èach person to select: --~
a desirëd level of firmness, and also to b~ able to chan~e each persons'~part of the mattress, either permanently or temporarily, in:response to a perceived need. Furthermore,~
this aspe~t of the; invention also seeks: to provide a mattress for two people in which the top 5urfac~ is~always :
at the same height across its full width, regardless of the - 2 ~

~ 3~ ;H~

2;12895 ,~ W093/03654 PCT/CA92/00 fixmness~es) selected, in which there is a smooth transition from one part of the mattress to the other, and also no signific~nt intervening gap.

It is known that by using various combinations of the currently available elastomeric foam materials tin the past, these were either natural or synthetic rubber; in more modern practice, polyurethanes are used), a level of variation of firmness can be obtained. Thus Hood, in U.S.

3,118,153 describes an upholstery construction wherein corners.:are strength ned by using two~ layers of soft foam with a layer of harder foam in bètweèn thëm.~ Boyles, U . S .
3, 534, 417 applies similar concep~s to a mattress, to provide some level of choice. A different level of firmness is obtained by turning over either the whole mattress, or an intermediate portion thereof extending across the full width of the bed. A11 of the mattress portions are enclosed within a: common easing. Whilst this does give a flat sleeping surface, on~ly a very: limited number of choices of firmness~ are provided.

Johnson, : U.S. 2,121~339 describes a more complicated system. The mattress consists of:two layers of foam of dif~ering firmness with a hard board layer in between them. The firmness is c~anged by reversing the elements making up the mattress. Thus, although a constant thickn~ss results, few choices o~ firmness are allowed.
For a double bed, it appears that the whole surface would have to have the same firmness. A similar mattress utilizing two layers of dissimilar foam is ~escribed by Slemmons, U.S. 3,110,4~2. In thiS mattress, two stacked resilient members are used of dif~erent firmness, with a provision to insert firming slats, èither at pr~determined points, or more or less anywhere, across the width of :the mattress. A mat:tress usin~ a plurality of foam pad elements is described by Betten-Zellekens in German SUB~ JTE SHEET

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W093/03654 ~ PCTJCA92/00 1,940,763. This mattress is somewhat similar to that ;~
described by Slemmons, in that a stiff, preferably plywood, panel i~5 included into the stack~ ~hus, although a '' plurality of foam elements is used, the only way to adiust the firmness is to reposition the plywood insert within the stack.
':, It has now been reali~ed that a mattress can be provided which both provides a uniform and constant sleeping surface height at substantially~the same level as a conventlonal bed, and~ yet~which pro~ides the,~:or each, :user with a high degree of choice of firmness. ~ ::
~ ', .
Thus, in its broadest aspect,~ this invention provides a mattress comprising ' combina~ion an assembly of mattress components chose~ from the group con~isting of:
(i) a plurality o~ foam mattress elements, at least one of which has a different hardness:to the ~thers;
,..
: : (ii) a plurality of first separa~ion~mean:s, i~
at least one of which is associated with~ each~ of the ~ foam mat~tress eleme~ts, permitting each mattress : element~ to: compLess and to lex:
separa~ely;~
(iii) at least one lightweight~substantiall~
rigid core element of substant~ially~th~
same length and wi~th as at least one of the plurality of foam mattress elements;
ti~~~ at least one:second~:separation means -~
between the rigid core element and the~
f~am mattress elements permitti~ng the' foam mattress elements adjacent the c~re element to compress and to flex :
separately; ~ ~:

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, .. .,,,,, , . ~, .. . . ... ............. .. ....... . ....

IW093/036~4 2 1 1 2 8 ~ ~ PCT/CA92/OO~X ~:, (v~ a ligh~weight substantially stiff torso ~',,.
board, substankially smaller in width -'' and length than at least one of the .~,"
plurality of foam mattress elements;
(vi) at least one surface element~on~the torso board constructed and adapted to retain the torso board in a chosen ~'' position in between two adjacent ~oam ' mattress elements, and .
~vii~, a contai~ment means adapted :a~d ~, ...
construc~ed ~to ensure :.~that~; the : ~ :
pluràlity of foam mattress,~;e~ements~
remain situated in their chosen order ; i :
in a substantially vertical stack, and to subject the plurality of~mattress ~ elements~to slight lateral compressio~
proYided that the ;mattress assembly includes ~t~ least .~,, components~ and ;Thus, ~in a :first ~more detailed~ aspect~ this~
invention: ~provides a~ ~mattress ~ which comprlses in combination~
a plur~ality of'foam;~mattress~elements~
at~least:~one:of which~has a~ dif~ferent ~
;hardness~t~o the others,~ ;,h~:
(ii) a~separation~means:between each':of the~
: mattress elements permit:ting~ ~e~ch~
mattress element~to~compress:;~an:d~to: ~ O
flex ~eparately; and ~iii) a containment~ means adapted~ and~
:''' co~structed to:~ ensure that: ~the~
plurality of:mattre:ss,elements~remain~
situated~in thei,r~chosèn order~:in~ a~
:~:substantially:~vertical ~stack,~and~:ta:~
: ~ subject the~plurality~ of mattress ~eleme~ts to slight lateral compression.: ~
: ~ 5 -~ :

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In a second more detailed aspect, this in~ention provides a mattress which comprises in combination:
~i) a plurality of ~oam mattress elements, at least one of which has a different ';
hardness to the others; --:
(ii) a lightweight substantially rigid core element of substantially the same ~' length and width as the foam mattress elements;
(iii3 a separation means between each of the :
mattress' elementsi and bètween the mattress elements and the rigid core element, permitting each mattress element to compress and to flex separately; and (iv) a containment means adapted and constructed to ensure th:at the plurality of mattres~s:elements~together : with the core element remain situated in : their chosan order ;in a :
.
s~bstantially vertical ~stack,~ and to -su~ject the plura:lity~ of ~mattress ~ ;~
elements:togethe;r~with the core~element ~ ~ :
to slight lateral~ compression.~ ;

In a third~more detailed aspeçt, this invention provides a mattress unit which comprises in combi~ation:
(i) a plurality of foam~mattress~elements, : ~
at least one of which has a different ~-hardness to the others;
(ii) a lightw~ight substantially rigid orso -~
board, substantially smaller in length :~
and width than the mat~:ress elements;
~iii) at least one surface element on the :
torso board constructed and adapted to retain th~ torso board in a chosen -SUE~ JTE~ SHIEET

. . W093/03654 ~ ~ 1 2 8 ~ 5 PCT/CA92/00~8 ,~
.~.
position in between two adjacent foam ~';
mattress elemen~s;
(iv) a separation means between each of the ~.
mattress elements, and between the mattress elements and the torso board, -:~
permi~ti~g each mattress element to move and to flex separately; and (~) a containment means adapted and ~;-constructed to ensure that the:
plurality of mattress elements togeth~r with :the torso board remain -in their chosen order in a substantia~ly ~ ~-vertical stack, and :to subject the plurality of mattress elements together with the core element to slight lateral compression.

In a further more detailed aspec~,:this inv~ntion provides a ~oam ma~tress comprising a foam~mattres-~ elem~nt of suitable length~ width, thickness,: and hardness, ~':
together: with~two lengthwise modulator panels along each lengthwise edge o~ the mattress~element, of medium hardness :~
foam.

~hus, in its broadest aspect, this invention provides a mattress comprising a plurality of foam mattress ;~
elements, which themselves provide a significant:range-o~
choices of firmness to the, or each, user.~ To this can ~e added a higher le~el of firmness, either o~er a partial :
area o~ the mattress by means of the torso-board, or o~er substan~ially the whole area of tbe mattress by means of the rigid core element. If deemed desirable,:both~a~torso board and a core element could be~ used toge~her. .
Additionally, all o~ these choices are availa~le ~o thet or each, user of the mattress. In the case o~:a doubl~ bed, if these choices are exercised in the manner set Xorth .;
-- 7 .
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bel~w, a substantially cons~ant top sheet height is maintained. Thus, although the two halves of a double bed may have remarkably different properties, the bed coverings present a flat top surface.

Alternati~ely, the preferred form of foam mattress element, used in the mattress sets, i~self, when used alone as a mattress, presents improved properties over ::
the commonly used simple foam slab mattxess. '2'.' ~ Preferably, ~ the ~plurality of foam mattress elements comprises a set of foam mattréss elements, sever~l of which have a different degree of firmness.
~, .
Preferably, at least one foam mattress element includes at least one lengthwise modulator paneI~:of medium ~:~
~ hard~ess foam. :-'':
:Preferably, in ~ mattress or mattress element :~
including modulator panels, the panels have a wedge-shaped ~:~
cross section, and~:are attached to a corresponding bevelled edge of the mattress or mattress element.

Preferably, the rigid core element has a layer of -~.
:: foam on its upper surface and a layer of foam on its lower sur~ace, and most preferably, the upper and lower layers of :~
foam are of different firmness. ~ ;i Preferably, the mattress elements comprising a single bed include one:rigid core element, or one: torso ~:~
: board, or both.

Preferably, the mattress elements comprising a double bed include two set8 0~ foam mattre~s elements, each about haI~ the width of the bed; with which may be combined ~
~, - 8 - ~.
~ ~, ~..
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W093f03654 211~ 8 9 5 PCT/CA92/00348 one or two rigid core elements each about half the width of the bed, and if desired, one or two torso boards.

Preferably, a torso board is used alone, vr separately for the, or eachl user of the mattress.
'''':'' Additionally, a torso board may be uséd in combination with a rigid core element, preferably placed above the c~re eIement and separated from it by at least one mattress element~

Preferably, the separatiQn means comprises at least one layer of fabric associated with at leas~ one face, of two contacting faces, o~ the mattress elements, a core element, and a torso ~oard, if presen~

Preferably,: the containment means~ comprises a ~itted sheet::means, which may further includs bo~h an:
additional lower surface, and openable closure mean~ to enable lau~derin~. ~Preferably,~ ~he: containment means includes a cradle: means adapted to retain, and to ensure~
~constan~ lateral pressure upon the ~attress elements.

In a further pxeferred alternative~combination, both a fitted sheet and; a cradle~ are used as the containment. ~f a cradle is used, a flat sheet tucked-in ~an also be used, rather than a fitted one.

Thus, for a double bed, the containment means can comprise one fitted~sheet means which contains the~two sets of mattress elements. In a further~optionl:~he cont~ainmen~
means ~can~compri~se in combination a first-~ and a~ second fitted sheet ~means each containing o~e set of mattress .
elements together w th a third fi~ted sheet means ~:
containing t~e two sets of mattress elements encased in the~;
fi:rst an~ the second :fitted sheet means. For each of these g _ :
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options, the assembled mattress can also be contained in a cradle means. ~

The invention will now be described by way of -reference to the attached Figures, in which: ~:
Figure 1 shows a single mattress, partly sectioned; ~:~
Figure ~ shows a double mattress and a cradle;
Figure 3 shows a detail of the cradle;
~ Figure 4 shows a mattress set for a double bed;
Figures 5, 6, 7, 8, 9, and lO show detail~ of ;~
mattress elemen~ construc,tion;
Figures 11, 12, 13, and 14 show detail~ of core element construction; .
Fi~ures 15, 16, and 17 show details of a second cradle construction to those shown in Figures 2, -~
3, and 4.
Figures 18 and 19 show details of a third cradle construction to those shown in Figures ~, 3 and 4; and Figure 20~shows a mattress incl~ding a torso board.
~; ""'~
In Figure 1 is shown perhaps the simplest form o~
construction for a mattress according to this invention.
: ~ The mattress shown generally as l consists~of five mattress ~;~: elemen~s 2, ~3, ~, ~, and 6, which are sized to be a snug ~ ~
fi~ into the containment means 8 which ensures~some ~' constant lateral pressure on all the mattress elements.
The elements can be ~rearranged in order to ~alter ~he ~:
hardnes's of the sleepin~ surface, since at least one::of~
them, for example 4, ~has a differe~t hardness; to the ~.
others. This aspect~of this invention wIll: be discussed ~urther, below. In Figure l, the co~tainment 8 is a fitted ~
sheet but, as discussed in detail later, other me~hods may also be used. In practice, the overall thickness of the '~:

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group of foam mattress elements is chosen so that the overall vertical thic~ness, as at x in Figure 1, is substantially the same as that of a conventional mattress. ;~
Hence, the containment means 8 comprising a fitted sheet -:
~ can be a conventional, readily available, ordinary fitted sheet. ~
~ ~ :
Two further optional features of this invention are shown in Figure 1. At the bottom of the set, there is present.a rigid rore elemènt 7,- the construction of which is discuss~d below. As shown,- lt~ls~ at the bottom, but it .
can be placed anywhere in the set, including at thé top, if a very hard surface is needed. At the top of the stack, within the fitted sheet 8, there is shown (partly cut away for clarity) a mattress pad 9. Generally this pad - which is commonly used on top of a~conventional:mattress - is a layer of cotton ~or synthet:ic) wool:;:batt, about 1 cm.
t~ick~ and is contained in a fabric cover. The mattress .- .
~over, if used, ~both adds to the overall comfort of the:
bed,~ and serves to protect the mattress~ elements: from soillng. Commercially available mattress ~ covers are commonly attached in much the same way as~a fitted sheet, as at 9A and 9B.

; As shown~in:Figure 1, the fitted sheet lncludes : a bottom retaining portion lO.: The mattress pad 9, when it incorporates the ~etaining parts 9A and 9B, will also:
include a bottom portion 9C. This provides some choice as to which of the~e will provide the containment means~ If it is ~hosen to: make use of the mattress pad ~assembl~y~as the:containment,~then the sides 9A, 9B and bottom 9C are so sized as to place th ~mattress elements under the required slight lataral compression. In that case, it is convenient~
to have the bo~tom portion 9C extend over the full area of the mattress; it i5 also then necessary to pro~ide ;a closure, such as a zipper, so that the containment can be SUE~STITUTE S~FEr .

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opened in order to change the sequence in the stack. The sheet 8 can then be an ordinary commercial fitted shee~, or it may even be a flat sheet tucked-in, although a fitted sheet is preferred.
.'; ~
Alternatively, the mattres~ pad need not provide the containment, which can be provided by the sheet alone, in which ~ase the sheet bottom portion 10 preferably extends over the full area of the mattress, and a closure, such as a zipper, is needed. In a third optiont--;both the sheet 10 and mattress pad;~assembly-9, 9A, 9B~ and- 9~ can contribute to the containment me~ns.

A further feature of Figure 1 should also be -~
noted. It can he seen that the mattress eIements 2, 3, 4, ~

5, and 6 are not all the same thickness. Hence, the i-overall firmness in such an arrangement is a ~unction of both the firmness of the foam used in each separate mattres-~ element, and the thickness of each element. A
thick,~irm element will hav~ more effect than a thi~ one.
For a single bedl variation in mattress elem~nt thickness presents no difficulties, slnce reg~rdless of~the sequence, ~' the set is always the same height. However, for a double ~ , ~ . . .
bed, problems might arise if the bed uses two sets of ~"
mattress elements. Interchanging elements between the sets could result in~ ~he two sets~ having different overall heights, which is inconvenient. It is therefore preferred, at least for a double bed, that all of the foam mattress .
elements be of essentially the same thickness.

The construction of each of the mattress elements is discussed in more detail below. ~
- ':
In Figure 2, a more complex arrangement is shown ~-representing a double bed mattress. The mattress shown generally at 11 comprlses two sets of mattress elements 12, SUt~ )Tl~ IEFI~

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13, 14, 15, 16, and 22, 23, 24, 25, and 26, and two rigid core elements 17 and 27. As shown, these are not in the same place. When both sets are assembled into the cradle 21 with the overall fitted sheet 8 ~shown cut away for clarity), the top surface of the sheet 8 is substantially flat.

Figure 2 also shows some further d~tails concexning various options in the separation means and the cont~;nment means.

The purpose of the~ separation means is to allow each foam mattress element to compress and to flex under the load imposed by the user. If no separation is provided, it appears that foam-to-foam friction relatively rapidly degrades the foam elements, especially in the main load areasJ which are usually~ substantially along the center of the mattress. To eliminate this ~riction~and to ensure that the mattress~elements are free to compress~and . :
to flex independ~ntly, the simple way is to encase eaeh i~
mattress element,~the~core element, and a torso board, ~as discussed below~, in~an individual fabric case, as at 20 ~or~
the element 12. A mattress pad as at 19 ;can~b~e provided '~
within such a case,~ or~it can be incorporated into the case. If such a~pad is used, it is~preferred~that ~it~ is included on both sides ~of~ the mattress, thus~avoiding the mattress elements becoming one-si~ded. Alternatively, the ~ ~' separation means can comprise a sheet of~fabric as at 29 glued or otherwise attached to at least one face of each mattress element, to the core element, and, if required, to ~a torso~board.; Again, to~avoid the elements becoming one~
sided, it is preferred to provide such~a sheet on both ;~
faces of ach~mattress element, gf the core~element, and of the torso board. ~

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If such an attached sheet is used, it need not be the full size of the mattress, and an edge border as at 29A, can be left unco~ered. It appears that leaving this edge area open to foam-to-foam fxiction is beneficial, particularly in a double bed having two mattress sets, as i~ helps in eliminating any separation between the two sets along the mattress centerline. Further, it is also possible to inclu~e a mat~ress pad, as at l9, either wi~h and as paxt o~ the sheet 29, or in conjun~ction~with it, so that the pad is somewhat smaller than the mat~ress element with whic~ it is associated. In that case:, it has beèn found beneficial to provide a shallow recess in the mattress element to receive the pad, so that the mattress element retains an essentially flat sur~ace.
, -.-.
For such ~ double~bed, it is also possible to use one, or more, mattress elements which are the~full size of ~he bed.

There:are several choices for the containment for ,:
a doub~e be~d, which;are much the same as those discussed above for Figure 1:. :~If:~a ~radle is used, ~s;is discussed -~.
below, then the overall ~sheet B:may be~omitted,~and each: ~
:mattress contained in~its own :sheet, a;s ~at 33 on the :~' element 12.

: It is also~possible to incLude a~ mattress pad ~ ;~
into the separation means,~ especially when this is an :
attached sheet,;such as 29 in FigurP 2.

The containment means, in addition to the overall ~.
fittéd sheet 8, and the pad:9~ may include a ~cradle. : One possibIe cradle arrangement, 21, shown in F~igures 2, 3,:and :
4, comprises a base 18, and corner .elements 28. These corners include a flex niche 28~allowing the corner to deflect, for example, when sat upon, as can be seen from . St)Bgl lTU~ IEE~
,~
, -2112~

Figure 3. The corners 28 are so spaced that when all of the mattress elements are stacked into the cradle, the two - sets will be under some slight lateral compression, in addition to any provided by a fitted sheet, such as 8. As ~ a consequence of the lateral compression, the corner elements also serve to substantially eliminate centerline separation. If a cradle is used, as is preferred for a double bed, then although a sheet will be needed usually, it does not have to be a fitted one forming part of the cont~ t.
., . , ,: .................................................... ~ .
.. , ,. , i . ,.
The manner of construction of the cradle depends upon the nature of the base to be used undernea~h it. If it is to be used on top of an existing boX spring base to replace an existing mattress, then the base 18 of the cradle can be relatively light material, for example the 3mm. thick hardboard known as masonite, and perhaps need not~be continuous coverin~ th~e whole area:of the bed~ It is also advantageous to provide some anchoring ~f the cradIe 18 to a box spring b:ase. Conveniently, this can ~e done by the use of cooperating velcro patches, as at 18A in Figure 3. Alternatively, if the cradle is to be placed on a~base, which provides adequate support only at the~ edges together with one or: two cross beams, such as a steel bed frame, th~n a much heavier material for the base~I8 will be ne~ded. For example, for a single bed it could be a sheet of 20mm. plywood of suitable size~ ~

As shown, the double bed of Figure 2 uses two sets of mattress elements. This is not necessary, as a perfec~y useable be~ can be made in the same way as in Figure 1, by using adequately:sized elements. However, in such an arrangement~, individual choice for each user is lost. Altexnatively, a mix of full width and half width mat~ress elements could be used, but again, the level of : personal choice is diminished, as shown in Figure 4. In ~ ~ - 15 -SUE~ UTE SHEET

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Figure 4 an end view is shown much the same as Figure 3, from which the containment, such as 8 in Figure 2, is omitted for clarity. The double bed mattress can be seen to be assembled from three sets of mattress elements, as ~:
follows:

(i) a first group of one person wide elements ~
14, 15, 16 and 17, in which the core element ~B
17 is roughly midway;
~ii) a second group of one:person wide elements ~--. 23, 24, 26 and 27, in which:the core element 27 is near the bot~om; and (iiil two full width elements 44 :and 45, one at ~
the top and the other lower down. .. :~:
~, Thus, the firmness of each of the user surfaces will depend to a degree on the firmnesses o~ the e.lements :' 44, 45 and the order in which:both:~they:~and~he remaining A
elem ts are~:assembled.

~ ~ In Figures 5, 6, 7, and ~ various methods of construction for~ each~ of the foam mattres:s elements are ~ ~ .
~ :shown. It is in:~the various available choices for::each of ~' the foam matt~esses making up a set that the flexibility to :~ .~
choose and~to vary the ~irmn;ess:of the overall :assemblage:~ '' is to be found. Each mattress~can differ:as to~its overall ~firmness, the inc.lusion of~modulator side~pane~ls, and'head and foot comfort panels.

An interesting feature in this~invention~is that .~-a;ma~tress element including modulator panels is useful of itself~ either as an additional overlay upon a conventional mattress, or if thick~enough as a foam mattress.

I~ :foam: mattress: construction, the inherent .~
firmness~ of ~ the foam material used is :important. :' , : ~;lJlB~ I I I UTE 8.1~

W093/03~54 211~ PCT/CA92/00 Unfortunately, commercial foam makers do not have a uniform :~
. .;
standard used in describing this attribu~e of a given foam. ~ .
The following information is given as a guide to the various levels of firmness used.
~. ';
Table 1 .!
,~.
Foam Characteristic (l) Com~ression:~2) , ;,...

~: . VS Very Soft ~ ' 1; 82 S : Soft -- ~ ~ 2.27 M : M~dium ~ . 22.7 H Hard 27.3 '~:
(l) VS, S, and ~are open cell foams; H may be open or closed cell foam.
(2) The~compression is measured by~determining : ~the~weight~ 'in: kg, required~t;o compress a 305mm:square'~piece of foam from~a~thickn~ss :of 102mm down to 76mm; hence, a hard:, stiff, foam :has a~::high~compression, and a~soft oam, a~low compression. ~

hil~t o~ten ~uoted,::: foam density is not overly important, as it is;~no~directly:related~to foam~firmness.
Genera1ly, foams with~a~;density of greater~than~3~2 kg/cubic metre are used. ~ Densit~ is more an indicat~ion of foam uality and;longevity, as low~ density foams ar~e general~ly~
s~ructurally weaker materials. These tend to fail under repeated ~ompression. ~A hiqher density~foam is generally : more resilient to~impàct, is structurally stronger, ~::and retains its properties better.

In ~he~drawings of:Fiq~res 5 through 9 both~the :casing, shown a5 20 in Figure 2, and any mattress pads, ; ~ ~ such as 19 or 29 in Figure 2, are omitted ~or clarity. In :; 17 -:
.
$UB~ii 111 UTE SHEET ~ ' 21128~i WO 93/03654 P~/CA92/003 use~ eac:h foam mattress element is provided with a separation means/ as described above.

The simplest form of foam mattress element, which '~
is suitable for a single bed but has certain disadvantages ~:
in a double bed, is shown in Figure 5 and comprises a simple foam slab 30 of the correct length, width, and thickn~ss. For all of the mattress elements (single or ~.
double) the length and width are chosen to fit the bed in ;.
question. The thickness is a separate variable~ We prefer that there are at least three, preferably five, possibly six, and perhaps even seven, separate mattress elements. :~
Thus~ the five mattress elements, plùs the core element, ~:
preferably will have a total thickness that fits a standard commercial sheet, and is equivalent to a normal mattress.
In North America, as this thickness is co~mo~ly 15 ~o '.
20cms., each foam mattress ls thus of the order of 3cms. ~;
thick. As ls discussed aboveD it is preferred that all of ~-~
the foam mattress elements should be of the same thickness, at least for a double bed. ~ :

In Figures 6 through 10 more complex constructions are shown. Figure 6 sh.ows an element inclu~ing a single modulator side panel 31 on one side of the main part 30 of the mattress, and Figure 7 shows two such modulator paneIs 31 and 32. As can be seen from Figure 9 which shows the top face of the mattress of Fi~ure ~.-7, the modulator panels 31 and 32 extend for the full ;' length of the mattress. The part section in Figure 10, on the line A in Figure 9, shows that these pan ls are tapered inwardly toward the center of the mattress, an~ the outer edge of the main part of the mattress has a corresponding bevelled face. ~.

The modulator panels are usually made from a medium foam. They serve in a single bed to provide an area - 18 - :
, .

$~ SHI~ ~

W093/036S4 2112 ~ PCT/CA92/00 of edge stiffness. In a double bed, the modulator panels, in addition to providing an area of edge stiffness, serve severa~ other functions, most of which are as a result of the wedge-shaped cross section used (see Figure 10). They help to minimize variation vertically in two sets of mattress elemen~s in a side-by-side relationship under compression due to body weight. They help to provide a smooth transition from the central area of each mattress element to the edge areas, thus avoiding an a~rupt change.
They help ~;n; m;Z~ sheet height variation on t~e center line, for example when two users are of significantly different weights. This: last is impossible with a conventional mattress.

As the modulator panels are usually made of medium foam, they are often not used with a medium foam mattress element, as in Figure 5. If only one~modul~tor is present, as in Figure 6, this would be used in a double bed, with the modulator panel at the center of the bed.
Generally it is~more~ convenient to include two modulator side panels 31 and 32. ' ~

Figure: 8 shows a more compl~ex five part mat mainly useful as the top mattress element in the set. The center panel 38 is chosen to be the desired hardness. ~The , ~
two side panels, 3~, 35, which can also be tapered as in -~
FigurP 10~ serve as moduIator panels. In this case, the ~;
side panels 34, 35 generally:are wider than the modulator panels. The two insert panels 36 and 37 are head and foot comfort panels. ~For example, 33 will be a relatively hard ~;~
..
foam, 34 and 35 both medium foaml and 36 and 37 a soft foam, but other combinations are contemplated.

When used as a mattress on its own, :and not as part of a set, the construction of Figures 7 and 8 offers -- 1 9 ~

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significant advantages over a simple foam slab, as is commonly used.
~ ',.
Figures 11, 12, 13 and 14 show the construction of the rigid core element, such as 17 and 27 in Figure 2.
The coxe element is s~own in part cut away plan in Figure 11, as an exploded diagram in Figure 12, and sectioned along the line B in Figure 13. An alternative partial section corresponding ~o the section in Figure I3 is shown in Figure 14.: The core element comprises a top first c~shion layer of ~oam 39, edge foam~pàn~ls ~0, a ce~tral stiff core 41, and a second cushion layer of foam 42. The central stiff corP is suitably lightweight compressed board, such as 3mm. hardboard (Masonite). Alternatively a suitably sti~f plastics board, such as ABS, could be used.
The edye foam panels 40 serve as a cushion to soften the edge of the element, and also in the same way as the modulator panelis described above. The two foam cushion layers 39 and 42 provide a:level of :softness in use~
Preferably, in ~hese layers the upper layer is of a medium foam, and the lower layer i5 a relatively so~t foam, and, as shown in Figure 13, one may be thicker than the other, thus providing two different levels of cushloning.
Preferably, the core element i5 also encased in its own suitable fabric casing, 43. In Figure 13 the edge foam panels 40 are shown as being of substantially rectangular cross-section. It is also convenient, as is shown in ~igure 14, to construct these as at 46 with ~ similar tapered shape/ as is used for the modula~or panels. In that case, the side edges of the cushion layers 39, 42 are also bevelled to accommodate the ~aper in the edge panels.

In Figures 15, 1~ and 17 is shown an alternative form of cradle for either a single bed, as in Figure 15, or a double bed, as in Figure 16. Details of the cor~er construction are shown in Figure 17. In these Figures, - 20 ~
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W093/03654 2 1 1 2 8 ~ S PCT/C~g2/00~

details of the mattress element construction are omitted for clarity. Further, the support options in Figures 15 and 16 can be interchanged.

Referring to Figure 15 first, a mattre~s shown generally at 50 is supported on an existing conventional b~x spring, 51~ The cradle comprises four corner elements 52, and four linking strap elements 53. The corners, 52, are attached to t~e box spring 51 by cooperating velcro patches, as at 54 Figure 16 shows a similar ~arrangement for a double bed with two mattress element sets, 50A and 50B.
Four corner elements 52 are connected by four linking strap elements 53/ and are attached to the ~ase by the cooperating velcro units 54. Other fix1ng means, such as a strap, could also be used. Two options for supporting ~he mattress are: shown; in practice, only one would be used, for the full width of the bed. On the left, as at 55~, a one piece relatively thick cradle bas~e is used, such as a sheet of~plywood. On the right, as at S6, a~sectioned ;cradle base compris:ing a plurality af support beams is used. Either of these bases could be used:~supported by~ a suitable bed frame.

:Figure 16 shows the corner in more detail~.~ The main body 52 of ~the: corner is made of a stiff, or stiffened, fabric, for example two layers of a decorative fabric with a layer ~f stiffening bonded therebetween. The bottom angle is strengthened with a plastic insert 58 this face rests:on~the underlying cradle support. Each vertical part of the corner includes a plurality of ,.
horizoIltal, 59, and vextical, 60, ~61, ~1exible stays. Gaps are pxovided~ between these ~ stays so: that the corner is ~-flexible, and will: bend, for example if the user sits down on the corner of the mattress. The linkin~ strap elements SUIE3~ ~ 1 1 UTE SHEET - ~
, . . . . .... ......... . .. . . . .

~ 1 1 2 ~
W093/03654 PCT/CAg2/00 53 are releasably joined to the corners 52 by ~asteners, as at 62, such as a snap. The corners and the lining strap "~
elements are so sized that when the mattress elements are inserted they are placed under slight lateral compression. ~:
In order to change the sequence in a ma~tress setr ei~her the set is removed and replaced, or ~ne of the linking straps is detached~ in order to free the set.
,~ ,' In Figures 18 a~d 20 a third form of cradle is shown; Figuxe 18 is a double bed, and Figu~e 20 is a single ~
bed... The arrangement of the mattress elements within the ~:
cradle is shown in Figure l9,~whicb is a part section on line C-C in Figure 18. Referring ~irst to Figure 18, the cradle shown generally at 63 is suppoxted on a support ~.
shown schematically at 64. The same considerations apply to the support 64 as have been discussed earlier.
~ ,~
The cxadle comprises ~a base, 65, with an :-.
upstanding core 66 around i:ts four edges. Agai:n, the nat~ure of the base chosen will be in large part determined by ~he nature of~the support 64~. The~outer face of ~he core is co~ered with a layer of upholstery foam 67, and then cased in suitable~ uph~lstery ~material 68. A filler layer, 69, may be included as:~well. The top'edge of the foam 67 extends inwardly up :above the co~e 66, on all four sides, tG provide an inward facing upholstered upper horizontal lip element 70. On the inner face of:the core similarly constructed lower vertical :lip eleme:nts: are provid~d, as at 71. As can be seen from Figure l9, the lower lip elements project inwardly the same:distance as the ~ppér one. These lip assemblies serve three i~terrelat d~purposes. First, they provlde an upholstered rim :all around the bed. Secondj they serve to hold the foam m~ttres9 elements in place, and to pro~ide the small amount of lateral compression needed, as the space inside ., -them ie a little small0r than the foam mattress elements.

~ .
;::
~UB~ UTE SHEEr ~;:

! W093/03654 21 1~ ~ ~ a PCT/CA92/00~8 Third, by being flexible, and by having free spaces as at 72 in between them, space is provided for tucking in - bedclothes, such as sheets and blankets.

A cradle of this type can be made as one pieee, as shown in Figure 20 for a single bed, or in two pieces if desired as shown in Figure 18 for a double bed.
, A further problem that can arise for the user of a bed is that it i5 desirable, on either a shor~ term ~asis as the result of injury,~for example,' hr on a~long term basis, to be able to make one area of a sleeping surface significantly stiffer than the remainder. With a normal mattress this is not easily achieved in any way that is comfortable. As is shown in Figure 20 this is easily achieved with a mattress according to ~this invention.
Although illustrated in Figure 20 for a single bed, the same procedure can be used in a double bed, when ssembled;
according to either of Figures 2 or 4. Suitable locations are indicated~at Y in:Figure 2l and Z in Figure 4.

: In Figure 20 is shown a:single bed using: the same form of cradle as is shown in Figure 18. ~Inserted into:the cradle shown generally~at:73 is a set of mattress~elements;
74, 75, 76, 77, 78, an~ 79. ~These mattress elements:are ~al~l constructed as~iscussed above, and:~generally will~be of differing firmness and will include a core:element.
Included in the set of elements is a torso board, 80. :As shown it is between elements 75 and 76. If placed higher, as at Y in Figure 2, a greater degree of firmnes~s is obtained. If placed lower, as at Z in Figure 4, a lesser degree of firmne5s is obtained. As shown in Figure 20, the torso: board, unlike the core element, is significantly smaller than the remainder of the elements ma~ing up the mattress, and consequently it will provide increased firmness over only a limited area of the mattress. Also as ~ - 23 -SUE~ UTE SHEI~

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a consequence of the smaller size, it can be located wherever it is needed. Thus unlike the core element the torso board can provide a harder area to support the spine, and yet still leave the remainder of the sleeping area acceptably soft.
~' The torso board is fabrica~ed from thin light weight material~ and generally is not padded like the core element. It is necessary to ensure that the torso board will remain where it is placed whilst the bed is in use.
Hence.it is desirable to have at least-one~relatively non-~kid surface. How this is achieved depends on the material use~ for the torso board. If it is fabricated from a thin stiff fibre board, such as masonite or hardboard, a fahric casing ~much the same as those used on the foam mattress elements as described ear~ier) is convenient. If it is fabricated from a plastic sheet, such as ~BS, thon no fabric casing appears to be needed. As the toxso board is relat$~ely thin, of the order of 5-l0mm, it can be added:to an existing mattres~ without materially affecting the overall thickness. Generally a torso board will be up to about l.7 m in length, and up to about l.0 m in width.
:~, I~ is also contemplated that both a torso board ~nd a ri~id ~ore element can be used together. Obviously, the core element would not be placed above the torso board, and likely would not be immediately below it. Thus in Figure 20 one of the mattress elements 77, 78, or 79 could comprise a core element.
,~
Exactly how the mattress is assembled depends on the desired level of firmness. For a very hard support surface, the core element, such as 17, 27 in Figure 2, is located on top of the mattress elements within: the .
containment means. To get a softer suxface, the core element is mo~ed d~wnward in the stack and one or more ::

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mattress elements are placed above it. This allows for a constant sleeping surface height, even in a double bed, with varying levels of firmness between the two sides.

If six mattress elements are available, which may include a rigid core element, each of which is of a different firmness, then there are up to 7~ possible combinations for the mattress. It should also be noted that where a plurality o* mattress elements are used, the firmness can be varied simply by changing~ the:sequence in which the mattress elements are stacked in the mattress co~tainment means abvve any base, such as~l8:in Figure 2.
~; ....
The foam mattress as disclosed herein/ and comprising at least a plurality of foam~mat~ress elements, is meant to act as a substitute or a replacement for a onventional mat~ress. In this sense, it requires a flat ~ , ~
substantially rigid base on which to rest. In:the absence of a flat substantially rigid sur~a.ce, the~màttress:herein described would require at least~one bed board to~act as ---the support surface. Thus,:the mattress herein described could rest on a conventional box spring or on a f~ame wi~h at least one:bed board thereon. If it;is:to be us~ed on a '' frame, khen it is convenient to use' a const~uction:
including a cradle,:such as is shown in Figt1res~2~ :15,~19, and 20. In that' case,~ the base of the cradle rather than i being a relatively light stif~ board material~such as~
masonite, advantageously is construct:ed~to provide a: : ~ f substantially rigid support surface for the mattress ~-~
elements. A cradle can also be constructed on a~box unit, suitabl~ upholstered~on its sides, to~ rep;lace the box .
spring ~nit commonly used beneath a conventional mattress. - .
It is thus apparent that the construction o~ the base part of the cradle is adapted to suit the properties of the sur~ace onto which ~he mattress unit and cr~dle will be '~
laid when in use.
- 25 ~
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SUESSl ITI)TE ~HE~T

21i~
WOg3/036~ PCT/CA92/003 : ". ' -~ .'~' ' As is discussed at same length above, it is very desirable to provide a containment means for a mattress according to this invention. The containment means can be chosen in several ways, in part by the mattress user and in part by the mattress ma~er. One option is to use a ~ conventional commercial fitted sheet, upon which the user lies, and whîch is removed for laundering. Such a fitted sheet generally encas s both the top, the sides, and a proportion of the ~nderside of the mattress, ~nd is elasticized at the edge in the head and foot areas to keep it in place. It is thus under some overall tension when installed on to a mattress, and therefor exerts a level of lateral compression on the mattress elements.

Altern~tively it is convenient to use a ma~tress pad assemb~y, either as the containment or in conjunction with a fitted sheet. Commercially a~ailable mattress pads are constructed in th~ same way as a fitted shèet and thus will provide the required lateral ~ressure on the mattress elements. This method has :the advantages thaè the pad will hold the stack as a coherent:assembly whilst the bed sheet is being changed.
In the preceding discussion the mattress elements, and the core element, are referred to as bein~
made fromJ or incorporate, "~oam". This term is weli understood in the upholstery art. It is used to refer to foam rubber, but latterly refers ~ ~oam materials made from synthetic polymers, including synthetic rubbers and other polymers. In modern practice, polyurethane materials are commonly used. These can be either open cell or:closed cell m~t-érials. Further, :it is also known to control the firmness of a fvam material by including deliberate voids within it, and to contour its surface. The voids commonly are deliberately shaped holes, such as cylindrical one~
The use of such procedures is within the concepts of this invention.

Sl)E~ JTE SHE~

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A multi-layer mattress comprising:
at least two mattress elements, at least one of which being a foam mattress element and having a different hardness from the others; and separation means for permitting each of said mattress elements to compress and flex separately when stacked one above the other.

2. The mattress according to claim 1, further comprising at least one substantially rigid core element of substantially the same length and width as at least one of said mattress elements.

3. The mattress according to claim 1, further comprising a substantially stiff torso board, smaller in width and length than at least one of said mattress elements.

4. The mattress according to claim 3, wherein said torso board is made of rubber.

5. The mattress according to claim 4, further comprising at least one surface element on the torso board constructed and adapted to retain the torso board in a chosen position in between two adjacent ones of said mattress elements.

6. The mattress according to claim 1, 2, 3 or 5, further comprising a containment means adapted and constructed to ensure that said mattress elements remain situated in their chosen order in a substantially vertical stack, and to subject said mattress elements to slight lateral compression.

7. The mattress according to claim 1, comprising two sets of said mattress elements, each of which being of the same length, width and thickness, and at least one further mattress element, said at least one further element being substantially twice as wide as the others, said mattress elements forming two side by side vertical stacks with said at least one further element spanning between said stacks, whereby a two-person bed is formed in which said at least two mattress elements can be interchanged between said two sets.

8. The mattress according to claim 1, comprising at least three said mattress elements each of which having a different hardness from the others, whereby by rearranging an order of said elements in said stack, more than two different hardness states of said mattress can be obtained.

9. The mattress according to claim 6, wherein the containment means comprises at least one standard fitted sheet, said stack having a height substantially equal to a height of a standard mattress normally receiving said standard fitted sheet.

10. The mattress according to claim 1, wherein the separation means comprises a sheet of fabric attached to one side of each said mattress element.

11. The mattress according to claim 10, wherein the separation means comprises a sheet of fabric attached to both sides of each said mattress element.

12. The mattress according to claim 1, wherein the separation means comprises a fabric casing around each said mattress element.

13. A mattress comprising:
a first foam mattress having a given hardness and at least one lengthwise edge modulator panel of a different hardness foam, the panel bordering between two sleeping zones; and a second mattress having a hardness other than said given hardness of said first foam mattress and being adjacent said modulator panel, said different hardness foam being selected to permit a firmness of said first foam mattress at said edge to substantially match said hardness of said second mattress at a corresponding edge thereof.

14. The mattress according to claim 13, wherein said first foam mattress includes two lengthwise modulator panels.

15. The mattress according to claim 13 or 14, wherein said at least one modulator panel is of a wedge-shaped cross-section, and said foam mattress has at least one corresponding bevelled edge.

16. The mattress according to claim 13, wherein said first foam mattress comprises a center panel, and a head and a foot comfort panel.

17. The mattress according to claim 13, 14, 15 or 16, wherein said second mattress is made of foam and includes at least one lengthwise edge modulator panel of a medium hardness foam adjacent said modulator panel of said first mattress, said modulator panel of said first mattress also being of a medium hardness foam.

18. The mattress according to claim 17, wherein said first and second mattresses comprise two sets of foam mattress elements arranged in side by side vertical stacks of substantially equal height, each said element being of the same length, width and thickness, whereby a two-person bed is formed in which said elements can be exchanged between said two sets.

19. A multi-layer mattress comprising:
at least two foam mattress elements; and separation means for permitting each of said mattress elements to compress and flex separately when stacked one above the other and subjected to use.

20. The mattress according to claim 19, further comprising at least one substantially rigid core element of substantially the same length and width as at least one of said mattress elements.

21. The mattress according to claim 19, further comprising a substantially stiff torso board, smaller in width and length than at least one of said mattress elements, whereby an overall firmness quality of said mattress can be changed by positioning said board at different levels.

22. The mattress according to claim 21, wherein said torso board is made of rubber.

23. The mattress according to claim 22, further comprising at least one surface element on the torso board constructed and adapted to retain the torso board in a chosen position in between two adjacent ones of said mattress elements.

24. The mattress according to claim 19, 20, 21, 22 or 23, further comprising a containment means adapted and constructed to ensure that said mattress elements remain situated in their chosen order in a substantially vertical stack, and to subject said mattress elements to slight lateral compression.

25. The mattress according to claim 19, comprising two sets of said mattress elements, each of which being of the same length, width and thickness, and at least one further mattress element, said at least one further element being substantially twice as wide as the others, said mattress elements forming two side by side vertical stacks with said at least one further element spanning between said stacks, whereby a two-person bed is formed in which said at least two mattress elements can be interchanged between said two sets.

26. The mattress according to claim 19, comprising at least three said mattress elements each of which having a different hardness from the others, whereby by rearranging an order of said elements in said stack, more than two different hardness states of said mattress can be obtained.

27. The mattress according to claim 24, wherein the containment means comprises at least one standard fitted sheet, said stack having a height substantially equal to a height of a standard mattress normally receiving said standard fitted sheet.

28. The mattress according to claim 19, wherein the separation means comprises a sheet of fabric attached to one side of each said mattress element.

29. The mattress according to claim 28, wherein the separation means comprises a sheet of fabric attached to both sides of each said mattress element.

30. The mattress according to claim 19, wherein the separation means comprises a fabric casing around each said mattress element.