1997 Volume 81 Issue 5 Pages 415-419
We analyzed the heat transfer characteristics of a new type of road traffic signal head developed to prevent the phantom illumination. A spherical multi-lenses-unit (lens-unit) is mounted in the traffic signal head. TS OR bulb with band mirror is employed as a signal lamp. The distribution of temperature in radial direction has a peak value at nearby 50mm on both surfaces of the lens-unit. The temperature at the position of 3 mm aparting from the surface of the lens-unit inside the signal lamp has a maximum at nearby 85mm. The distance of 50 or 85mm is measured from the center of the lens-unit. The rising curve of the temperature with time shows good agreements between experiment and calculation on surface side of the lens-unit inside the signal lamp. For a sheet of vertical flat-plate assumed for the lens-unit, a calculation shows that the temperature in axial direction rapidly decreases within the distance of 5 mm from the outside surface of the lens-unit.