Road marker or light based warning device
A road marker and related light based warning device are described. The road marker or device includes a thermal sensor that triggers the illumination of at least one light-emitting diode at a predetermined temperature. The temperature may be associated with ice formation. The light-emitting diode(s) may flash to alert motorists to hazardous road conditions. The road marker or device utilize simple components to increase reliability, particularly when the device is subjected to high heat such as when the device is mounted into hot tar seal. The device further includes a switching element that prevents rapid on/off cycling.
1. A road marker including a housing enclosing passive electrical components including at least one light-emitting diode coupled with at least one thermal sensor;
wherein the at least one thermal sensor has at least 0.5° C. of hysteresis to prevent rapid on/off cycling of the at least one light-emitting diode; and
wherein the at least one light-emitting diode illuminates when the thermal sensor detects a predetermined temperature.
2. The road marker as claimed in claim 1 wherein a surface of the housing is transparent.
3. The road marker as claimed in claim 1 wherein the road marker further includes a circuit board coupled with the at least one thermal sensor and at least one of the at least one light-emitting diode.
4. The road marker as claimed in claim 1 wherein the road marker further includes a photovoltaic (PV) module.
5. The road marker as claimed in claim 1 wherein the road marker further includes at least one energy storage element.
6. The road marker as claimed in claim 1 wherein the at least one thermal sensor and the at least one light-emitting diode are located within the housing and there are no external parts outside the housing.
7. The road marker as claimed in claim 1 wherein the at least one thermal sensor is at least one bimetallic switch.
8. The road marker as claimed in claim 1 where in the degree of hysteresis is biased towards the at least one light-emitting diode remaining illuminated until at least 0.5° C. or higher than the set temperature so as to ensure that temperature conditions are suitably warmer than a temperature considered hazardous.
9. The road marker as claimed in claim 1 wherein the housing is biased to a position where the at least one light-emitting diode in the housing sits proud of a surface to which the road marker is applied and wherein, when a force is applied against the bias direction, the housing is depressed into the surface.
10. The road marker as claimed in claim 1 wherein the road marker further includes:
a circuit board coupled with the at least one thermal sensor and at least one of the at least one light-emitting diode;
a photovoltaic (PV) module;
at least one energy storage element; and
a forward biased diode between the PV module and the at least one energy storage element preventing energy leakage from the at least one energy storage element when light energy is insufficient to power the PV module.
11. The road marker as claimed in claim 1 wherein the at least one light-emitting diode flashes when the at least one thermal sensor detects a predetermined temperature.
12. The road marker as claimed in claim 11 wherein the at least one light-emitting diode flashes at a frequency of 1-5 Hz.
13. The road marker as claimed in claim 1 wherein the predetermined temperature is less than or equal to an ambient and/or surface temperature of 5° C.
14. The road marker as claimed in claim 1 wherein the road marker is a cat's eye.
15. The road marker as claimed in claim 1 wherein the road marker is placed or fixed to a road surface.
16. The road marker as claimed in claim 1 wherein the road marker is placed or fixed to an intermediate structure.