The Vacuum Fluorescent Display (VFD), a kind of triode electron tube, has been in the market for 21 years since it was developed first. The first feature was of a 7 segmented type and then a variety of types, 5×7 dot character type, dot matrix type, complex-pattern type, etc. were successively developed in the sequence. Today, ultra-small active-matrix VFDs using MOSFET substrates are under development. The low voltage drive is known as a distinctive feature of VFDs. However the emission color of all early VFDs was limited to blue-green only. The current VFDs are enable to emit almost all colors, such as red, orange, lemon and etc.. Thus VFDs have taken place of other display devices and occupies an important position. Problems for future VFDs developing highly efficient phosphors that can emit multi-color, fabrication of the high resolution phosphor screens, elimination of the vacuum exhaust tube, etc. are pointed out.
