Image Number 4 for United States Patent #6127780.
A flat photoluminescent lamp has external walls and a plurality of internal walls designed to form a serpentine channel having first and second ends. First and second electrodes, positioned in proximity with the first and second ends of the serpentine channel generate a plasma discharge therebetween in response to the application of power to the electrodes. A heater element, comprising a thick film cermet material is disposed on the bottom external surface of the lamp. The heater element is serpentine in shape and substantially follows the path of the serpentine channel. Disposed on opposite sides of the heater element are serpentine conductors, also comprising a thick film cermet material. A DC voltage is applied to the heater element to maintain the internal temperature of the lamp at a desired temperature value. A temperature sensing element may also be used to control the power applied to the heater element. For operation in a low intensity mode, an AC signal is applied to the serpentine conductors causing the generation of an electric field within the interior portion of the lamp throughout the serpentine channel. A low level electric discharge field within a serpentine channel results in the generation of visible light at low intensity levels.