   thumb|right|vfd display, all segments are visible due to external ultraviolet illumination a vacuum fluorescent display (vfd) is a display device used commonly on consumer-electronics equipment such as video cassette recorders, car radios, and microwave ovens. the first vfd was the single indication dm160 by philips in 1959.http://www.radiomuseum.org/tubes/tube_dm160.html the first multi-segment vfd was the 1962 japanese single-digit, seven-segment device. the displays became common on calculators and other consumer electronics devices.joseph a. castellano (ed), handbook of display technology gulf professional publishing, 1992 isbn 0-12-163420-5 page 9 unlike liquid crystal displays, a vfd emits a very bright light with high contrast and can support display elements of various colours. vfds can display seven-segment numerals, multi-segment alpha-numeric characters or can be made in a dot-matrix to display different alphanumeric characters and symbols. in practice, there is little limit to the shape of the image that can be displayed: it depends solely on the shape of phosphor on the anode(s). hundreds of millions of units are made yearly.joseph a. castellano (ed), handbook of display technology gulf professional publishing, 1992 isbn 0-12-163420-5 page 176 == design == the device consists of a hot cathode (filaments), anodes (phosphor) and grids encased in a glass envelope under a high vacuum condition. the cathode is made up of fine tungsten wires, coated by alkaline earth metal oxides, which emit electrons when heated by an electric current. these electrons are controlled and diffused by the grids, which are made up of thin metal. if electrons impinge on the phosphor-coated plates, they fluoresce, emitting light. unlike the orange-glowing cathodes of traditional vacuum tubes, vfd cathodes are efficient emitters at much lower temperatures, and are therefore essentially invisible.joseph a. castellano (ed), handbook of display technology, gulf professional publishing, 1992 isbn 0-12-163420-5 chapter 7 vacuum fluorescent displays pp. 163 and following the principle of operation is identical to that of a vacuum tube triode. electrons can only reach (and "illuminate") a given plate element if both the grid and the plate are at a positive potential with respect to the cathode. this allows the displays to be organized as multiplexed displays where the multiple grids and plates 
Vacuum_tube_displays