GB2332466A - Road reflectors - Google Patents

Abstract

A road reflector comprises a thermochromic plastics material which indicates the presence of icy conditions, the reflective portion being made of the thermochromic plastics material, which would change colour then be reflected back to the driver of an oncoming vehicle, indicating the presence of ice and hopefully save lives.

Description

(1) road reflectors 2332466 This invention concerns road reflectors and

particularly road reflectors for giving a warning of icy conditions.

Road reflectors are widely used to give a visual warning to drivers at night, for example of road layout, such studs including a reflective portion which reflects incident light from the headlights of a vehicle. as a result, the driver can be made aware on unlit roads of changes in direction of the road and also of entries to and exits from the carriageway on which the vehicle is being driven.

It has been proposed in GB2121460-A to provide road marker studs which also provide an indication of the formation of ice on the road, the studs including glass reflex reflectors mounted in a depressible housing located in the road, the reflectors having a hollow lens' containing a crystal of liquid which changes colour as its temperature approaches the freezing point of water. the change in colour of the crystal or liquid which occurs at such temperatures results in a change in the colour of light which is reflected back to the driver indicating the possibility of ice on the road (2) According to the present invention there is provided a road reflector the reflective portion comprising a thermochromic plastics material which changes colour at about the freezing point of water.

The temperature at which reflectors in accordance with the present invention change colour will in general be selected to provide drivers with a warning of ice before it forms, for example at a temperature of about 5'C.

The thermochromic plastics material, which is preferably durable is reflective to provide drivers with an indication of it's presence, the colour of the reflected light depending on the colour of the themochromic plastics material and thereby its temperature.

An embodiment of the road reflector in accordance with the present invention will be described, by way of example, with reference to the accompanying diagrammatic drawings in which:- Fig, 1 is a perspective view of the road reflector and road reflectors.

Fig. 2 is a perspective view of a road with a plurality of road reflectors disposed along it's centre line.

The road reflector shown in Fig. 1 is of generally known construction and it consists of a block 1 of durable material having reflectors 2 and 3 mounted thereon. In use, as shown in Fig. 2, the block 1 is built into a road surface so that one or other of the reflectors 2 and 3 can reflect light from an approaching vehicle back to the driver of the vehicle. At night, drivers of vehicles approaching the road reflectors 10 from opposite directions are made aware of the presence of the road reflector 10 by light reflected back to them by lights on their respective vehicles.

Unlike prior reflectors of the type shown in Fig. 1, the reflective portion of the present invention is of a durable thermochromic plastics material so that it changes colour according to the ambient temperature to which it is exposed.

(3) Thermocromic plastics materials which can be used for the purpose known in the plastics art, different materials being used to obtain different colour changes at different temperatures.

The temperature at which the reflectors change colour is preferably above the freezing point of water because, as will be appreciated, the block 1 inevitably has a thermal capacity which results in changes in it's temperature lagging behind changes in that of surrounding air, As a result, if the colour change of the reflector is to provide a reliable indication of the possible formation or ice on a road in which the road reflector is located, it will almost inevitably have to occur at a temperature above the freezing point of water.

Fig. 2 shows a plurality of road reflectors 10 in accordance with the present invention built into the centre line of a road, the air temperature being such that patches of ice 11 are beginning to form on the road surface.

Although the present invention has been particularly described with reference to the use of a durable plastics material for the block 1, it should be appreciated that the reflectors 2 and 3 can be of a thermochromic plastics material and the durable block 1 can then, if desired, be of a thermochromic: or non-thermochromic plastics material, for example a durable material which has been proposed for use in road marker studs.

(4)

Claims (6)

Claims

1. A road reflector comprising a thermochromic plastics material which changes colour at about the freezing point of water.

2. A road reflector according to claim 1, wherein the temperature at which the thermochromic plastics material changes colour will be selected to provide drivers with a warning of ice before it forms, for example at a temperature of about 5'C.

3. A road reflector according to either of the preceding claims, wherein the thermochromic plastics material is reflective to provide drivers with an indication of it's presence, the colour of the thermochromic plastics material and thereby it's temperature.

4. A road reflective according to either of claims 1 and 2, wherein the thermochromic plastics material is substantially reflective and the road reflector includes at least one reflector which reflects incident light of a colour which depends on the colour of the thermochromics; plastics material and thereby its temperature.

5. A road reflector according to any of the preceding claims, wherein the thermochromic plastics material is durable.

6. A road reflector according to claim 1, substantially as herein described with reference to the accompanying drawings.