U.S. patent application number 12/134296 was filed with the patent office on 2009-12-10 for artificial playground surface with grass.
This patent application is currently assigned to MATTA IP LIMITED. Invention is credited to Paul Harris.
Application Number | 20090305798 12/134296 |
Document ID | / |
Family ID | 41400819 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090305798 |
Kind Code |
A1 |
Harris; Paul |
December 10, 2009 |
ARTIFICIAL PLAYGROUND SURFACE WITH GRASS
Abstract
A multi-layered surface suitable for a playground, including a
top layer of perforated resilient mats is also provided with a
bottom shock-absorbing layer having pockets or perforations capable
of supporting the growth of grass or other plant material from
under the mats. A middle mesh layer helps distributes forces
sideways. This invention overcomes the inherent absence of
resilience in grassed playgrounds and is compatible with formal
tests for impact resistance. The resulting playground environment
is more natural in appearance than that of an undressed plastics
mat surface.
Inventors: |
Harris; Paul; (Auckland,
NZ) |
Correspondence
Address: |
YOUNG & THOMPSON
209 Madison Street, Suite 500
ALEXANDRIA
VA
22314
US
|
Assignee: |
MATTA IP LIMITED
Auckland
NZ
|
Family ID: |
41400819 |
Appl. No.: |
12/134296 |
Filed: |
June 6, 2008 |
Current U.S.
Class: |
472/92 ;
428/22 |
Current CPC
Class: |
E01C 9/004 20130101;
E01C 13/083 20130101 |
Class at
Publication: |
472/92 ;
428/22 |
International
Class: |
E01C 13/08 20060101
E01C013/08 |
Claims
1. An artificial surface for a children's playground wherein the
artificial surface is resilient and is further comprised of a
plurality of layers; the layers providing for the support of a
plurality of living plants namely grass plants; the layers being
perforated thereby forming an array of apertures over the surface
extending downwards to a lower layer bearing soil; said apertures
allowing the plants to grow upwards through the apertures in the
mats and above the artificial surface.
2. An artificial surface for a children's playground as claimed in
claim 1 wherein the plurality of layers comprises a first,
uppermost layer made of a flexible, moulded or cast material in the
form of a plurality of cast, laterally joinable modular mats; each
mat including a plurality of perforations and an embossed upper
surface, a second layer comprising a stiff, perforated sheet or
mesh, supported upon a third layer comprising a thick resilient
weight-bearing layer including a plurality of cavities; each cavity
being capable of holding at least one living plant within a support
matrix, so that the living plants can, when in use, grow upwards
through the perforations in the mats and above the artificial
surface.
3. An artificial surface for a playground as claimed in claim 2,
wherein the mats of the first layer are comprised of a plastics
composition including polyvinyl chloride, at least one plasticiser,
and at least one filler.
4. An artificial surface for a playground as claimed in claim 3,
wherein the composition of the first layer further includes a
coloring material.
5. An artificial surface for a playground as claimed in claim 3,
wherein the first layer is spaced apart from the mesh layer by the
provision of a plurality of downwardly projecting pegs forming part
of the first layer all of which pegs, when in use, rest upon the
middle layer.
6. An artificial surface for a playground as claimed in claim 5,
wherein the second (mesh) layer is relatively stiff so that a load
applied from the uppermost surface over a small area is at least
partially distributed in a sideways direction yet the second layer
includes sufficient perforations to allow plant material to grow
through the middle layer.
7. An artificial surface for a playground as claimed in claim 6,
wherein, when in use, the surface has sufficient impact absorbtion
capacity characteristics for use as a children's` playground (as
determined by an appropriate standard test method) and includes
structural modifications providing for the germination and growth
of grass so that the grass emerges through the artificial
surface
8. An artificial surface for a playground as claimed in claim 1,
wherein the third layer is water-resistant and water-permeable and
is resilient.
Description
FIELD
[0001] This invention relates to artificial surfaces for
recreational use; more particularly to surfaces having a
predetermined "resilience" characteristic and especially to
artificial playground surfaces compatible with the growth of
vegetable material especially grass.
BACKGROUND
[0002] Natural playground surfaces are well-known. One of the most
common is earth (soil) that may or may not have at least one grass
species growing in it. The present invention is particularly
concerned with children`s` playgrounds, where children run about
and interact with playground equipment. Note that some of these
sports may from time to time involve hard physical impacts by
children with the ground. At times a natural earth (soil) surface
may become quite hard and the risk of actual injury becomes
high.
[0003] There is such a material as "artificial turf". However
sliding contact by (for example) children`s` knees almost always
results in a form of cutting damage to the skin because the strips
of plastics material of which the artificial turf "leaves" are made
is capable of cutting skin.
[0004] Artificial playground surfaces are becoming common,
particularly for unstructured play by children involving swings,
slides and similar apparatus. Children can fall off such apparatus,
and even when landing from an ordinary slide, a child may sustain
injury such as head or neck injury and long bone (femur, tibia,
fibula etc) fractures if the surface causes a sudden stop.
Problem to be Solved
[0005] Given the aforesaid, it would be useful to somehow combine a
grass surface (which has the property of regeneration) with an
artificial surface that meets or exceeds the Standards so that at
any given time, a player can make impact with the surface yet be
relatively unlikely to be injured. The general public is becoming
aware of a need to ensure that artificial playground surfaces are
as safe as possible. The American Society for Test Methods (ASTM)
has published a Standard: Impact attenuation of surface systems
under and around playground equipment, no F 1292 2004. It would be
desirable to provide a playground surface that meets standards of
this type.
Object
[0006] The object of this invention may be stated as to provide (in
combination) a grass surface with an artificial surface for
exercising or play, or at least to provide the public with a useful
choice.
STATEMENT OF INVENTION
[0007] In a first broad aspect this invention provides a resilient,
play-compatible artificial surface also capable of supporting
vegetation; wherein the resilient artificial surface includes a an
array of pockets capable of supporting germination and growth of at
least one species of plant so that the surface is more natural than
a surface lacking controlled vegetation.
[0008] Preferably the artificial surface for a children's
playground wherein the artificial surface is resilient and is
comprised of a plurality of layers; the artificial surface
including means for the husbandry or support of a plurality of
living plants; the layers being perforated thereby forming
apertures extending downwards from an uppermost or first surface
and to a lower layer bearing soil; said apertures allowing the
plants to grow upwards through the apertures in the mats and above
the artificial surface.
[0009] Preferably the living plants are comprised of at least one
species of plant including a type of grass (Order: Graminale--the
grasses, sedges and rushes); and more particularly the at least one
species is selected from Family Poaceae: the grasses.
[0010] In a related aspect, the resilient artificial surface
includes a plurality of layers, including (from the top) a
sculpted, perforate, resilient surface comprised of repeating units
called "mats" each including a border carrying interlocking means
about all sides (for locking into adjacent mats), an upper or first
surface including a plurality of relatively large perforations, and
a plurality of supporting legs each of which supports an adjacent
portion of the surface above a lower layer, then a middle or second
force-distributing layer comprised of a relatively rigid mesh
having a plurality of holes, that lies over a third or lower
relatively thick shock pad layer, made of a resilient fibrous
substance, including pockets or perforations approximately aligned
with the relatively large perforations of the mats.
[0011] Preferably the third layer is water-permeable and
water-resistant, since it will often be wet.
[0012] Optionally the second layer may be replaced by a layer of
geotechnical cloth which is perforated in places aligned with the
cavities of the third or shock pad layer.
[0013] Optionally; depending on the local weather patterns, the
type of soil underlying an area to be covered, and the
configuration of the land, the third or shock pad layer may be laid
upon a substrate or layer capable of providing adequate drainage,
such as a layer of gravel or a combination of soil including
drainage tiles or pipes.
[0014] When in use, the perforations/cavities of the third or shock
pad layer are filled with soil and grass seeds, from which grass
will or does grow upwards and eventually though the perforations of
the mats above.
[0015] In a second broad aspect the invention provides a method of
using the plurality of layers, comprising preparing a substrate,
laying the shock pad layer (which may be provided as a roll)
optionally on the substrate, at least partially filling each of the
perforations/cavities in the shock pad layer with a
growth-compatible matrix and then of adding a mixture of matrix and
grass seeds into each perforation; then laying the mesh (which may
be provided as a roll) on top, and then laying a plurality of mats
on top of the mesh, locking the sides of the mats to each other by
one or more means including interdigitating lugs, welding or
gluing, fixing the periphery of the array of mats to a bordering
object, and then of watering the resulting playground surface from
time to time so that the grass will germinate and grow and emerge
through the apertures in the mats.
[0016] The periphery of the array of mats may be fixed using
concealed plastics pins or spikes or by other means, including
burying the outer mats under soil.
[0017] In a related aspect the grass may be mowed, fertilised and
watered from time to time, since contact wear by human activity
will vary from place to place.
[0018] In a further related aspect new seed may be distributed over
the surface from time to time, in order to sow new grass. For
example, extremely cold or dry weather conditions may have killed
the grass.
Preferred Embodiment
[0019] The description of the invention to be provided herein is
given purely by way of example and is not to be taken in any way as
limiting the scope or extent of the invention.
[0020] Throughout this specification unless the text requires
otherwise, the word "comprise" and variations such as "comprising"
or "comprises" will be understood to imply the inclusion of a
stated integer or step or group of integers or steps but not the
exclusion of any other integer or step or group of integers or
steps.
DRAWINGS
[0021] FIG. 1: is an "exploded" diagram showing a section through a
portion of a resilient playground surface before grass growth has
commenced.
[0022] FIG. 2: is an "exploded" diagram showing a section through a
portion of a resilient playground surface after the grass has grown
and has been mown.
[0023] FIG. 3: is a top view of part of a preferred artificial mat,
including the apertures.
[0024] FIG. 4: is an elevation cross-sectional diagram of part of a
preferred artificial mat in plan view, along the line A-A in FIG.
3.
[0025] FIG. 5: is a diagram of part of a preferred mesh in plan
view.
[0026] FIG. 6: is a plan view of part of a preferred shock mat
material.
[0027] Note that FIGS. 3-6 are approximately to scale.
EXAMPLE 1
[0028] The American Society for Test Methods (ASTM) has published a
Standard Test Method for impact attenuation of surface systems
under and around playground equipment: F 1292 2004. According to
the invention to be described in this specification, it is now
possible to fabricate a playground surface that meets or exceeds
the Standards, and which includes real grass.
[0029] The natural appearance of the artificial surface of this
invention relies in part on the inherent capability of grass leaves
to grow throughout their length, not just at a growing tip as is
the case for most other plants. Hence damage to the protruding tips
of the grass plants does not prevent further growth. This
characteristic may have evolved during grazing pressure from
animals, because those types of plants that lose their growing tips
will not survive grazing. Grass (the Family Poaceae: the grasses)
as a botanical class evolved relatively recently. In this
application this property allows the grass beneath the surface to
keep on growing despite damage from time to time at the protruding
tip. The term "grass" includes all those species and strains that
are already used as "turf" in playgrounds, but is not limited to
those species and strains. It may be found that tougher leaves are
required and this requirement may apply more particularly in areas
that experience higher wear.
[0030] Please note that the elevation sections--diagrams FIGS. 1
and 2 are "exploded" diagrams in which layers 101, 102 and 103 are
separated for purpose of clarity. The layers are normally in
contact with each other and with the ground or other substrate
(120) below.
[0031] The artificial surface (100) which is the basis of this
invention is shown in FIGS. 1 to 6. It is comprised of a plurality
of layers, the topmost of which is a sculpted, perforate surface
(112) made of repeating units herein called "mats" each including a
peripheral border 113 (in FIG. 3) that is provided with
interlocking (interdigitating) means about all sides for locking
into adjacent mats. Suitable interlocking means are for example
pegs and sockets, and other joining devices and the use of gluing
or welding, separately or together. Such joining means are not
shown, being known to those skilled in the relevant arts. The upper
surface of each mat 101A includes a plurality of relatively large
perforations 107 (for example the size of each perforation is about
1 inch square, with rounded corners), and a plurality of hollow
supporting legs 105 having central apertures 106 each of which
supports an adjacent portion of the surface above a separate, lower
layer. Some of the legs may be only half-cylinders (as referred
along the cylinder axis) in order to be more flexible. In one
practical embodiment, the legs are connected to each other by
under-surface "beams" 114 moulded from the composition used to make
the mats. FIG. 4, a section taken along the line A-A in FIG. 3,
shows the heights of the beams. The top surface of the mats layer
is preferably provided with extra grip or frictional areas that
grip against the soles of children's footwear, such as by means of
small, slightly raised (typically 0.5 inch) sharp-edged shapes such
as the squares 112 best shown in FIG. 3. The total thickness of the
mats layer is--as shown by indicator 101--typically about one inch.
The mat structure includes (a) an upper surface 101A which is
typically 0.2 inch thick, which includes integral strengthening
beams 114 of about 0.16 inch thickness that are formed beneath the
upper surface where they form connections between one supporting
leg and any adjacent supporting leg. The strengthening beams
surround apertures 107 which in one example (see FIG. 3) are about
1 inch square spaced apart from each other by about 0.8 inches.
Four supporting legs 105 at 2.2 inch centre spacing surround each
aperture. Each leg extends 1 inch down from the upper surface, has
a diameter of 0.65 inches and an internal aperture 106 of 0.3
inches diameter. Since the legs are hollow, they can support the
underside of the mat at about 0.7 inches above the layer below,
hence creating a space, while having more inherent resilience than
a solid rod in case of direct impact.
[0032] The resilience that is required of the playground surface
arises from: [0033] a) flexibility of the mat material itself,
leading to deflection on impact of the material around the legs;
[0034] b) presence of voids such as apertures 106 and 107; [0035]
c) the height of the space beneath the mat surface; [0036] d)
compressibility or "bendability" of the legs 105, some of which may
be only half-round; [0037] e) stiffness of the screen-like layer
103; and [0038] f) compressibility of the underlying shock pad
layer 104.
[0039] All of these characteristics may be determined at the time
of manufacture, taking environmental temperatures and ageing and
like parameters into account, so as to satisfy the standards that
may be imposed by the relevant authorities or by common sense.
According to this invention, the impact properties are relatively
independent of the quality of an installer's work. At the tile of
preparing this specification the inventors do not expect the plant
material to contribute much to the impact test properties of the
entire surface, but will wait to see what the properties will be
over time.
[0040] Flexibility of the material itself is provided by a
combination of detailed structural configuration, and selection of
suitable materials. The mats are preferably made of a plastics
material by casting into a mould, and a composition including
polyvinyl chloride plus suitable plasticisers and other additives
(as is known to those skilled in the relevant art) is currently the
preferred plastics material. Rubber, and synthetic rubber are
optional compositions. Alloys or mixtures of those materials, or
other options also exist or may be developed. As is well known in
the art, colouring matter and/or weathering resistance-promoting
materials are examples of additives to the composition of the
mats.
[0041] The underlying layer (102) see FIG. 5, on which the mats are
placed preferably comprises a relatively rigid, tough sieve or
mesh-like sheet comprised in this Example of an array of about 0.32
inch holes (102A) separated on average by about 0.12 inch of 0.05
inch thick solid polypropylene material. FIG. 5, from a photograph,
serves to show the relative proportions of holes to material. This
relatively rigid mesh (commonly called "oyster mesh") helps to
distribute any load applied from the mats above in a sideways
direction so that the underlying layer 103 is not broken down or
ruptured and so that the playground characteristics remain
consistent. The relatively smaller holes of the mesh help to
exclude larger foreign bodies from the layer below yet allow growth
of the plant material from below. The shock pad layer 103 comprises
a relatively thick (in one example; about 1.4 inches thick) layer,
made of a resilient fibrous substance including an array of
cavities or perforations 108 of about 0.8 inch diameter at about 2
inch spacing, that is preferably placed in approximate alignment
with the relatively large perforations of the mats 107. Preferably
these cavities are partially open to the surface below, so that
soil and other materials placed within tends to remain, but plant
roots can travel down into the substrate 120. Even if the
perforations of and above the shock pad layer are not aligned, the
inherent phototrophic nature of grass growth confers the growing
tips with an ability to seek out nearby apertures 107 and grow up
through them, as shown in FIG. 2. One example material used for the
shock pad layer 103, (see FIG. 6, which is derived from a
photograph) comprises a randomly oriented, loose array of adherent
rubber shavings which altogether occupy about 40% of the volume of
the shock pad (the spaces being filled with air--or water when in
use) that are adhered together by a glue such as a vinyl-based
material. The deformability of the shock pad layer has not been
measured, but a strong squeeze by a thumb approximately halves the
thickness of the shock pad layer. The cavities or perforations 108
may be made at the time of manufacture of the shock pads, or may be
cut afterwards.
[0042] The invention is installed by a method of placing each of
the plurality of layers over an area of ground which is to receive
the artificial playground. This area may even be an old playground
surface that requires upgrading. Optionally, depending on the local
weather patterns, the type of soil underlying an area to be
covered, and the configuration of the land, the shock pad layer may
be supported upon a substrate layer 104 capable of providing
drainage, such as a levelled layer of gravel or a combination of
soil or sand that may include drainage tiles or pipes 111. It is
likely that the roots (202) of the grass plants will in time invade
the soil in layer 104, or enter the soil beneath.
[0043] Then, the shock pad material (typically supplied in a roll)
is placed on the substrate so as to cover the substrate surface and
each of the perforations 108 in the shock pad is at least partially
filled with a growth-compatible soil 109 (including fertiliser as
required) and then a mixture of soil (or other matrix known in the
horticultural arts, such as a water-absorbent jelly) and grass
seeds (110) is added on top, into each perforation. In FIG. 1, only
one of the perforations 108 is shown with the added mixture of
seeds and soil. This process may be sped up using an array of
funnels pressed into a metal sheet (for example); the inter-funnel
spacing matching the spacing of the array of perforations 108. Then
the oyster mesh 102 is laid on top, and finally a plurality of mats
101 are placed on top of the oyster mesh and locked together by
their sides using one or more means (such as interlocking
processes, glue, or welding. The periphery of the array of mats (A)
is fixed to the ground by methods such as pinning with stakes (such
as a provided type of concealed plastic stakes, burying the edge
under soil, or fixing the mats overall edge to a perimeter wall, so
that the top surface does not creep over time or come loose and
present a hazard. Finally, the resulting playground surface is
watered according to standard turf management practice so that the
grass 110 will germinate and grow and in time its leaves 201 will
emerge through the apertures 105, 106 in the mats. Meanwhile the
roots 202 will emerge below the shock pad material
[0044] The impact properties of the surface should be tested at the
time of installation by an approved standard method, in order to
demonstrate that the desired amount of resilience is present.
[0045] From time to time the grass leaves 201 may be mowed,
fertilised and watered so as to provide a controlled height 200,
just as for any other turf. Contact wear by human activity will
vary from place to place such as at the ends of slides or under
swings. It is possible that over time the space beneath the mats
and above the mesh will become filled with foreign matter so that
the resilience properties of the surface are altered. The mats
layer 101 could be pulled up for cleaning a few times during the
working life of the surface, or a form of vacuum cleaning or water
hosing may be used. The apertures 108 may be seeded or re-seeded
from above, through the mat apertures.
Variations
[0046] Preferably the at least one species of plant is a type of
grass (Order: Graminale--more particularly the grasses, sedges and
rushes). Some pockets may instead be filled with clover or a
grass/clover mixture, in order to fix nitrogen and provide a
self-fertilising function. More than one kind of grass seed may be
planted, so that a combination of quick (re)growth and a durable
surface is provided.
[0047] The layers may be supplied separately or together, as is
convenient.
[0048] The mats may be pre-connected into larger rectangles or into
rolled strips.
[0049] The soil and the grass may be locally sourced.
[0050] The invention may be further developed for use in grounds
where team sports such as football are played and a controlled set
of impact properties are required.
INDUSTRIAL APPLICABILITY AND ADVANTAGES
[0051] The playground surface looks more natural at least from a
horizontal aspect because of the presence of many tufts of grass
growing up through the holes.
[0052] The surface will be less likely to injure users than the
commonly used alternatives (such as an ordinary lawn, with grass
growing from soil, or artificial turf), because it includes a
designed component of resilience: the layer of mats in co-operation
with the shock pad layer below. More particularly, the incidence of
such injuries as head and long bone injuries should be reduced.
[0053] The lawn surface will regenerate more quickly after damage
than a plain grass/soil lawn, since some of the length of each of
the leaves of the grass is always protected from damage as a result
of being under the plane of the layer of mats.
[0054] The surface may be designed in order to meet certain
national or international standards, which may be an at least
partial defence against personal injury law suits.
[0055] Finally, it will be understood that the scope of this
invention as described by way of example and/or illustrated herein
is not limited to the specified embodiments. Where in the foregoing
description, reference has been made to specific components or
integers of the invention having known equivalents, then such
equivalents are included as if individually set forth. Those of
skill will appreciate that various modifications, additions, known
equivalents, and substitutions are possible without departing from
the scope and spirit of the invention as set forth in the following
claims.
* * * * *