a large area multi - channel flat fluorescent lamp with improved efficiency consists of two groups of closed hollow electrodes which are printed on the inner surfaces of the opposing ends of two flat glass substrates . the substrates are sealed together and have wave - guiding spacers which protect the lamp from implosion and also maintain a fixed spacing between the two substrates . a dielectric reflective layer is coated on the inner side of one of the substrates with an over - coat of phosphor , and the inner opposing surface of the other substrate is coated with only the phosphor . the space between the substrates is first evacuated and then filled with an inert gas and mercury vapor . the multi - channel closed hollow electrode structure with wave - guiding spacers , in combination with a reflective dielectric layer produces greater brightness with better brightness uniformity over a large area . in addition , the large area multi - channel flat fluorescent lamp maintains high efficiency and has a long life .