AN IMPACT RESISTANT PAD

Abstract

An impact resistant pad, for example, for a garment such as a glove (10). The impact resistant element is formed of a plurality of upstanding interconnected walls (1) arranged in a lattice pattern, the lattice being arranged in a Penrose tiling pattern.

Description

The present invention relates to an impact resistant pad.

The pad has applications in any number of areas where there is a need to absorb an impact applied to the surface of the pad.

Such applications may, for example, be garments such as gloves, shoulder pads, kneepads, etc. or may be other devices such as cases for mobile phone devices.

Such impact resistant pads are known with various patterns of ribs and protrusions which are generally provided in order to give a localised increase in thickness of a resilient material in order to improve impact absorption, while the intermittent nature of the ribs does not unduly add material and hence cost and weight to the pad.

An example in the field of impact resistant gloves is a pad with an upstanding wall formed as a lattice. The lattice has a hexagonal honeycomb arrangement to provide impact absorption in two ways. Firstly, resilient deformation of the material in the direction of the impact causes a certain amount of energy absorption. Secondly because the walls of the lattice are connected in the honeycomb structure, the impact is transmitted from one hexagonal structure to the next via the interconnected walls thereby dissipating the impact laterally across the pad. Whilst this is reasonably successful, the symmetrical nature of the honeycomb structure means that, as the shockwave spreads out across the pad, parts of the shockwave may interfere with one another and the symmetrical arrangement increases the likelihood that at any point of interference, the wave will be in phase thereby reinforcing the localised shockwave at the point of intersection.

The present invention aims at addressing this problem.

According to the present invention, there is provided an impact resistant pad according to claim 1.

By arranging the wall of the lattice in a Penrose tiling pattern, the above mentioned problem is solved. A Penrose tiling pattern is a non-periodic pattern created by an aperiodic set of prototiles. These prototiles come in at least two different polygonal shapes which are arranged in an aperiodic manner in order to fully cover a surface without gaps.

This lattice structure, the walls of which follow the path of the junctions between the prototiles, therefore provides an efficient way of creating an impact resistant element which can cover a surface area with walls with a reasonably regular spacing. It therefore provides similar benefits to the above mentioned honeycomb structure.

However, because it does not have the symmetry of the honeycomb structure, shockwaves are not spread out across the pad in a regular manner. Thus, where a shockwave travelling through one wall meets a shockwave through an adjacent wall, there is a much higher probability that the two waves will not reinforce one another and instead cancel one another out at least to some extent. Overall, therefore, the pad of the present invention is much more efficient at dissipating a force normal to the pad in a lateral direction across the pad.

Initial tests have shown that, as compared to a hexagonal lattice of a comparable size, impact protection efficiency is improved by as much as 46%, suggesting that a significant mass saving may be made to impact protection elements by incorporating Penrose lattices. This benefit may provide significant cost savings in manufacture and transport and improved comfort for the wearer.

Penrose lattices are known in a nature at an atomic level, for example in aluminium alloys. They are also known as a mathematic phenomenon as discovered by Roger Penrose. The only practical implementation that we are aware of is as a tiling pattern, e.g. for flooring. As far as we are aware, it is not known in the prior art to make use of the practical properties of the pattern in terms of a relatively uniform spacing which is non-periodic.

The walls alone may form the pad. However, preferably the impact resistant element is connected to an underlying substrate. This may be an additional layer within the pad, but preferably the underlying substrate is part of a garment. The garment or other article may me made of a single material with the walls directly formed in that single material.

The walls of the pad may be ceramic or composite, but are preferably a deformable material for example they may be polymeric.

The mean height of the wall is preferably 1-20 mm, preferably 1-15 mm, and more preferably 1-10 mm. The mean width of the wall is preferably 0.2-5.0 mm, preferably 0.2-3.0 mm, and more preferably 0.2-2.0 mm.

The intersection between three or more walls is defined as a node, and the mean spacing between nodes is preferably 3-30 mm, preferably 3-20 mm, and more preferably 3-15 mm.

The pad is preferably incorporated into a garment. These garments may also incorporate flexible impact absorbing features formed of a plurality of interconnecting walls having auxetic properties. Walls with auxetic properties will cover a larger area in a perpendicular direction to the applied force when stretched. These can be used in regions of the garment which are required to flex to a greater degree than others, for example at the knuckle joints of a glove. In these regions, the lattice structure could limit flexibility, so the presence of the auxetic walls here will sacrifice some of the impact resistance of the lattice for the increased flexibility of the interconnecting walls.

The garment may be a glove. Alternatively the impact resistant pad may be incorporated into a case for a mobile communication device with a screen such as a mobile phone.

The pad may be moulded or extruded but is preferably 3D printed.

Examples of an impact resistant pad will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a pad with a rear wall;

FIGS. 2-4 show examples of different sizes of Penrose lattices that can be used for the pad;

FIG. 5 is a plan view of a glove showing the layout of a number of pads on the glove;

FIG. 6 is a plan view of a glove showing how the Penrose lattice is positioned on the glove; and

FIG. 7 is a perspective view of a mobile phone case incorporating a pad.

The impact resistance pad has a plurality of upstanding walls 1 with a distinctive configuration. The pad may be a self-contained pad as shown in FIG. 1, which has a rear wall 2 from which the pads are upstanding. Alternatively, it may be incorporated into an underlying structure as described below. In this case, it may still have the rear wall 2, or this may be provided by components of the underlying structure.

The walls 1 are arranged such that they follow a path which is defined by the junctions of adjacent tiles in a Penrose tiling.

The Penrose tiling is known in the art. It is a form of aperiodic tiling. The tiling covers a plane with non-overlapping polygons or other shapes such that the shifting any tiling of the shapes by a finite distance, without rotation, cannot produce the same tiling.

One form of a Penrose lattice structure is shown in FIGS. 1 to 4. The central part of the structure is shown in FIG. 2. This is based around seven kite-shaped polygons 3 having the same shape and size arranged around a central point 4. Outside of the central structure there are further rings of various kite-shaped structures, FIGS. 3 and 4 then show further rings of polygons based around the same central core as FIG. 2.

All three of these arrangements from FIGS. 2 to 4 have the same outer perimeter, such that the lattice effectively increases in the density from FIGS. 2 to 4.

Several different categories of Penrose lattice are known in the art, such as pentagonal tiling, kite and dart tiling, and rhombus tiling. Any one of these are suitable for use in the present invention.

As will be apparent from FIGS. 1 to 4, the elements making up the lattice have a reasonably uniform size meaning that they provide reasonably uniform coverage of the surface without leaving undue gaps to ensure that the surface for which impact resistance is required does not have unwanted exposed areas. The density of the lattice can be set in order to ensure that the open areas between the walls are not unduly large.

As will also be appreciated from FIGS. 1 to 3, any impact perpendicular to the plane of the page (for FIGS. 2 to 4) is transmitted along with the walls as it is spreads through the pattern structure. Although the tiles of the lattice have a relatively constant shape, the walls do not follow a regular pattern. As the impact spreads through adjacent walls, where these walls meet, it is unlikely that the shockwave at this point will be in the same phase as the shockwave from an adjacent wall. The shockwave is therefore likely to be cancelled to some extent at an intersection.

A first implementation of the pad is shown in FIG. 5 which relates to a glove 10. Such a glove is intended for applications where protection of the hands against impact is required.

The glove may be covered with a single pad having a Penrose lattice pattern. In this case, a relatively large pad 11 covers the part of the glove which, in use, will cover the back of the wearer's hand. In the part of the glove which will, in use, cover the knuckles, there is a region 13 with a number of upstanding walls 13 which have an auxetic configuration. These provide a reasonable degree of flexibility in the vicinity of the knuckle joints. However, when a wearer grips an object, the auxetic nature of walls will provide enhanced protection for the knuckle joints at that time. In the finger and thumb regions 14, a more conventional protective pad may be used.

A second implementation of the impact resistant pad is shown in FIG. 7 which represents a phone case 20. In most ways, this is conventional in that it has a generally rectangular configuration. It has four side walls 21 with a number of openings 22 to allow access to ports in the phone and a number of depressible features 23 to allow operation of the phone buttons. The case has a rear face 24 which is provided with the impact resistant pad 26 with the walls being arranged with a previously described Penrose lattice pattern. These ways may either extend internally of the case such that they contact the rear of the phone, or may be an outwardly protruding ribs protruding from the rear face of the case. The pattern shown in FIGS. 1 to 4 shows the pattern applied to a circular configuration. However, it is simply a matter of redefining the boundary of the pattern to have the rectangular configuration of the case. It is not necessarily for the tiling pattern to have the above described circular boundary.

Claims

1. An impact resistant pad comprising an impact resistant element formed of a plurality of upstanding interconnected walls arranged in a lattice pattern, the lattice being arranged in a Penrose tiling pattern.

2. The impact resistant pad according to claim 1, wherein the impact resistant element is connected to an underlying substrate.

3. The impact resistant pad according to claim 2, wherein the underlying substrate is part of a garment.

4. The impact resistant pad according to claim 1 wherein the walls are resiliently deformable

5. The impact resistant pad according to claim 1, wherein the mean height of the wall is 1-20 mm.

6. The impact resistant pad according to claim 1, wherein the mean width of the wall is 0.2-5.0 mm.

7. The impact resistant pad according to claim 1, wherein intersection between three or more walls is defined as a node, and wherein the mean spacing between nodes is 3-30 mm.

8. A garment incorporating the pad according to claim 1.

9. The garment according to claim 8 incorporating a plurality of the pads according to claim 1.

10. The garment according to claim 9, wherein further comprising flexible impact absorbing features formed of a plurality of interconnecting walls having auxetic properties.

11. The garment according to claim 8, wherein the garment is a glove.

12. A case for a mobile communication device with a screen, incorporating a pad according to claim 1.

13. A method of forming an impact resistant pad according to claim 1 by 3D printing the walls.