The present invention relates generally to guideposts, and more particularly, to a flexible photo-luminescent guidepost for delineating roadways and foot paths.

BACKGROUND ART

Guideposts are used to indicate the varying contours and directions of the approaching section of road to drivers. However, a problem with prior art guideposts is that they only reflect light in the direction of the light source (that is, they are retro-reflective). Thus, the contours of the road beyond a vehicle's headlights are not easily visible to the driver. This can be a safety hazard on unlit or poorly lit roads. The same problem applies to pedestrians walking or jogging on unlit or poorly lit foot paths.

Photo-luminescent guideposts have not previously been largely adopted because they do not have the intensity or duration necessary to glow overnight for up to 12 hours, or in colder conditions. Moreover, these prior art photo- luminescent guideposts do not have retro-reflectors, so that prior art photo- luminescent guideposts appear to disappear when they are directly exposed to the headlights of an oncoming vehicle. Another problem with prior art photo-luminescent guideposts and other prior art guideposts made of timber or metal, is that they are not resistant to impact. Flexible guideposts do not require replacing as often as timber and metal guideposts, and so are more cost effective to install in the long term.

Accordingly, it is an object of the present invention to provide a photo- luminescent and flexible guidepost that substantially overcomes at least some of the deficiencies of the prior art. DISCLOSURE OF INVENTION

According to a first aspect of the present invention, there is a provided a guidepost comprising a body made of a polymer integrated with phosphorescent pigment so as to make the guidepost photo-luminescent and a thermal energy storage cell within the body.

The thermal energy storage cell may be filled with a heat retaining material. The heat retaining material may take the form of a liquid, a gel or a solid. In a preferred embodiment of the invention, the gel is adapted to produce heat under compression, and the polymer is adapted to shrink with decreasing temperature, so as to excite the phosphorescent pigment in the body.

The polymer may be integrated with glass bubbles bonded to the phosphorescent pigment. Preferably, the body comprises 80 to 90% polymer, 1 to 10% phosphorescent pigment and 1 to 10% glass bubbles.

The guidepost may further include a flexible hinge attached to a base which is adapted to be attached to the ground.

At least a portion of the body may be made of a polymer which has a high level of elasticity and resilience, so as to make the body flexible and resilient.

Preferably, the guidepost includes at least one retro-reflector. According to a second aspect of the present invention, there is provided a guidepost comprising a body, a base and a flexible hinge connecting the body and the base, wherein the hinge includes a bracket adapted to be attached to the base, and wherein the body is adapted to connect with the bracket in a manner so as to align the base and the body. The flexible hinge may also include a module adapted to be attached to the body, wherein the module is adapted to connect with the bracket in a manner so as to align the base and the body.

The flexible hinge may include a plastic polymer band with resilient properties, which connects the bracket to the body or the bracket to the module.

Preferably, the body of the guidepost is photo-luminescent. More preferably, the body includes a thermal energy storage cell filled with a heat retaining material, so as to increase the photo-luminescence of the body. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of a flexible photo-luminescent guidepost according to a first preferred embodiment of the invention; Fig. 2 is an exploded view of the guidepost of Fig. 1 ; Fig. 3 is a perspective view of the guidepost of Fig. 1 , in use; Fig. 4 is a partial cut-away perspective view of the guidepost of Fig. 3;

Fig. 5 is a close-up view of the guidepost of Fig. 4; Fig. 6 is a perspective view of the guidepost of Fig. 1 , adapted for use on a roadway;

Fig. 7 is a perspective view of the guidepost of Fig. 6, in use; Fig. 8 is a perspective view of a photo-luminescent guidepost according to a second preferred embodiment of the invention; Fig. 9 is an exploded view of the guidepost of Fig. 8; Fig.10 is a perspective view of the guidepost of Fig. 8, in use; Fig.11 is a partial cut-away perspective view of the guidepost of Fig. 10; Fig. 12 is a close-up view of the guidepost of Fig. 11 ;

Fig. 13 is a close-up partial cut-away view of the guidepost of Fig. 8; Fig. 14 is a perspective view of the guidepost of Fig. 8, adapted for use on a roadway;

Fig. 15 is a perspective view of the guidepost of Fig. 14, in use; Fig. 16 is a perspective view of a guidepost according to a third preferred embodiment of the present invention;

Fig. 17 is an exploded perspective view of the guidepost of Fig. 16; Fig. 18 is a perspective view of the guidepost of Fig. 16, in use; Fig. 19 is a partial cut-away view of the guidepost of Fig. 18; Fig. 20 is a close-up view of the guidepost of Fig. 19; Fig. 21 is a close-up partial cut-away perspective view of the guidepost of Fig. 16; Fig. 22 is a perspective view of the guidepost of Fig. 16, adapted for use on a roadway; and

Fig. 23 is a perspective view of the guidepost of Fig. 22, in use. MODES FOR CARRYING OUT THE INVENTION

A guidepost 10, shown in Figs. 1 to 7, has a photo-luminescent body 12, which preferably comprises about 87% polymer, 9% phosphorescent pigment and 4% glass bubbles.

A suitable polymer is Polyethylene, which has good impact and flexural strength characteristics. A person skilled in the art will appreciate that the present invention is not limited to this particular polymer, which is provided by way of example. The polymer may contain other components or additives, such as UV stabilisers, impact modifiers, or plasticisers.

A suitable phosphorescent pigment is a rare earth doped alkaline earth metal aluminate such as "LumiNova G-300" sold by Nemoto & Co Ltd from Japan (see US 5,686,022 and US 5,424,006). LumiNova is a Strontium- Aluminate crystal doped with trace amounts of Europium and Dysprosium (SrAI ₂ O ₄ : Eu, Dy), which produces a yellowish-green glow. Other suitable phosphorescent pigments include halogenated alkaline earth metal aluminate doped with rare earth element activators, such as those available from Visionglow Pty Ltd in Australia (see PCT/AU2006/001609). These include 0.04SrO. 0396SrF ₂ . AI ₂ O ₃ : 0.002Eu, 0.008Dy which produces a green glow, 0.04CaO. 0.96CaF ₂ . AI ₂ O ₃ : 0.0025Eu, 0.010Dy which produces a blue glow and 0.04SrO. 0.96SrF ₂ . 2AI ₂ O ₃ : 0.0019Eu, 0.0009Dy which produces an aqua glow. A person skilled in the art will appreciate that the present invention is not limited to these particular phosphorescent pigments, which are provided by way of example.

Suitable glass bubbles include the K15 or S22 models of soda-lime- borosilicate glass bubbles (having particle size ranges of 30 μm to 115 μm and 20 μm to 75 μm respectively) sold by 3M Company in the USA. A person skilled in the art will appreciate that the present invention is not limited to these particular glass balloons (also known as 'ceramic balloon microspheres'), which are provided by way of example. For instance, the glass bubbles could be replaced with silica particles, such as expanded perlite.

To make, for example, 15 kilograms of photo-luminescent material suitable for use in one or more guideposts, one must firstly add 600 grams of glass bubbles to 80 grams of a 15% hydrochloric acid solution in a tumbler powder mixer having an airflow drying and vapour venting system. The mixer is then sealed and agitated for about 15 minutes. Secondly, in order to bond the pigment to the bubbles, the mixer is opened and 1400 grams of phosphorescent pigment is added to the mixer which is then sealed and agitated for about three hours or until the mixture is dry. Thirdly, 13 kilograms of polymer is melted and the mixture of phosphorescent pigment and glass bubbles is added to the surface of the heated polymer to allow integration of the mixture through the polymer. Fourthly, the melted composite of polymer, phosphorescent pigment and glass bubbles is moulded or extruded in the form of the guidepost 10 and allowed to solidify whilst cooling. A person skilled in the art will appreciate that the present invention is not limited to the particular method of manufacture described, which is provided by way of example.

A thermal energy storage cell 14 (see Figs. 4 and 5) is moulded into the photo-luminescent body 12. The cell 14 is adapted to be filled with a heat retaining material in order to enhance the excitation of the phosphorescent pigment in dark and cold conditions. The heat retaining material may be a fluid such as salt water, or glycols such as those used as engine coolants, or Dowtherm A™ which is a eutectic mixture of biphenyl and diphenyl oxide. Alternatively, the heat retaining material may be a gel (such as disclosed in US 5,006,586) comprising polyvinyl alcohol, borate glass, and water. The gel may be adapted to produce heat under compression, and a portion of the photo- luminescent body, such as the polymer, may be adapted to shrink with decreasing temperature, so as to excite the phosphorescent pigment in the photo-luminescent body 12 and thereby increase the photoluminescence of the guidepost overnight. Alternatively, the heat retaining material could also comprise a solid, such as rubber sponge, a synthetic rubber such as Neoprene, a form of foam, or even rice. A plug 16 (see Fig. 5) may be used to keep the heat retaining material within the cell 14.

A retro-reflector 18 is affixed to the photo-luminescent body 12 and reflects light in the same direction as a vehicle's headlights to indicate a driver's immediate position on a road, while the phosphorescence allows the driver to delineate the road ahead. The retro-reflector 18 may be affixed within a recess in the photo-luminescent body 12 to assist in protecting the retro-reflector 18 from damage if the guidepost 10 is struck. A base 20 of the guidepost 10 may take the form of a stake 22 (see Figs. 1 to 5) which may be made of metal or glass reinforced plastic. Alternatively, the base 20 may take the form of a mount 24 (see Figs. 6 and 7) which can be bonded to a road using bitumen, epoxy or mechanical fasteners. A hinge 26 mateably connects the photo-luminescent body 12 to the base 20. The hinge 26 is made of a flexible and resilient polymer, such as polyurethane, preferably with a hardness of around Shore A 60. If the photo- luminescent body 12 is impacted (see Fig. 3), the hinge 26 enables the body 12 to resume an upright position. As shown in Fig. 5, the inside of the hinge 26 has barbs 28 which grip barbs 30 on the base 20 and barbs 32 on the photo- luminescent body 12. Straps 30 in the form of stainless steel cable ties may be secured around the hinge 26 over the photo-luminescent body 12 and base 20. Attachment means other than the straps 30 could be used, such as plastic packaging straps, clamps, bolts, or rivets. A guidepost 32, shown in Figs. 8 to 15, has a photo-luminescent body 34 which includes a thermal energy storage cell 36 (see Fig. 11) adapted to be filled with any of the heat retaining materials referred to above. A plug 38 (see Fig. 13) may be used to keep the heat retaining material within the cell 36. A retro-reflector 40 (see Fig. 8) is affixed to the photo-luminescent body 34. The guidepost 32 has a base 42, which may take the form of a stake 44 (see Fig. 8) or a mount 46 (see Fig. 14). A hinge 48 connects the base 42 to the photo-luminescent body 34. The hinge 48 comprises a stretchable band 50 having a thread 52. The stretchable band 50 is inserted into the photo- luminescent body 34 and is held in position using a pin 62 which passes through a hole 64 in the photo-luminescent body 34 and the stretchable band 52 (see Figs. 12 and 13). The thread 52 is then passed through a bracket 54 and a washer 56 into the stake 44 (see Fig. 9) or the mount 46 (see Fig. 14) and is secured with a nut 58. As the nut 58 is tightened, the stretchable band 50 is tensioned. The bracket 54 is secured to the stake 44 using screws 60.

A guidepost 66, shown in Figs. 16 to 23, has a photo-luminescent body 68 which includes a thermal energy storage cell 70 (see Fig. 19) adapted to be filled with any of the heat retaining materials referred to above. A plug 72 (see Fig. 20) may be used to keep the heat retaining material within the cell 70. A retro-reflector 74 (see Fig. 16) is affixed to the photo-luminescent body 66. The guidepost 66 has a base 76, which may take the form of a stake 78 (see Fig. 16) or a mount 80 (see Fig. 23). A hinge 82 connects the base 76 to the photo-luminescent body 68. The hinge 82 comprises a module 84 which mateably engages the photo-luminescent body 68 and holds it using screws 86. A stretchable band 88 made of an elastic polymer is moulded into the module 84 and a bracket 90 (see Figs. 18 and 20), using an over-mould or insert-mould method of manufacture. The module 84 and the bracket 90 may be made from High Density Polyethylene (HDPE) or from die-cast alloy. The bracket 90 is fastened to the stake 78 (see Fig. 17) or the mount 80 (see Fig. 22) using screws 92.

Various modifications may be made in details of design and construction without departing from the scope and ambit of the present invention. For example, any combination of the guideposts could be used with any combination of the hinges, or bases referred to in the specification. Any design of guidepost, hinge or base similar to the embodiments of the invention described in the specification is within the scope and ambit of the present invention. INDUSTRIAL APPLICABILITY

The present invention has applications in the road and transportation industry for delineating roadways and footpaths at night.