Vacuum fluorescent display

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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.[1] 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.[2] 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.[3]





The light emitted by most VFDs contains many colours and can often be filtered to enhance the colour saturation providing a deep green or deep blue, depending on the whims of the product's designers. Phosphors used in VFDs are different from those in cathode-ray displays since they must emit acceptable brightness with only around 50 volts of electron energy, compared to several thousand volts in a CRT.[7]



A digital dashboard cluster in an American automobile.

During the 1980s, this display began to be used in automobiles, especially where car makers were experimenting with digital displays for vehicle instruments such as speedometers and odometers. A good example of these were the high-end Subaru cars made in the early 1980s (referred to by Subaru enthusiasts as a digi-dash, or digital dashboard). The brightness of VFDs makes them well suited for use in cars. Current models of Renault MPV, Scenic and Espace both use VFD panels to show all functions on the dashboard including the radio and multi message panel. They are bright enough to read in full sunlight as well as dimmable for use at night. This panel uses four colours; the usual blue/green as well as deep blue, red and yellow/orange.

This technology was also used from 1979 to the mid-1980s in portable electronic game units. These games featured bright, clear displays but the size of the largest vacuum tubes that could be manufactured inexpensively kept the size of the displays quite small, often requiring the use of magnifying Fresnel lenses.[citation needed] While later games had sophisticated multi-colour displays, early games achieved colour effects using transparent filters to change the colour of the (usually light blue) light emitted by the phosphors. High power consumption and high manufacturing cost contributed to the demise of the VFD as a videogame display. LCD games could be manufactured for a fraction of the price, did not require frequent changes of batteries (or AC adapters) and were much more portable. Since the late 1990s, backlit colour active-matrix LCD displays have been able to cheaply reproduce arbitrary images in any colour, a marked advantage over fixed-colour, fixed-character VFDs. This is one of the main reasons for the decline in popularity of VFDs, although they continue to be made. Many low-cost DVD players still feature VFDs.





Emission may usually be restored by raising filament voltage. Thirty-three percent voltage boost can rectify moderate fade, and 66% boost severe fade. This can make the filaments visible in use, though the usual green-blue VFD filter helps reduce any such red or orange light from the filament.


The first VFD was the single indication DM160 by Philips in 1959. It could easily be driven by transistors, so was aimed at computer applications as it was easier to drive than a neon and had longer life than a light bulb. This was made obsolete by LEDs. The 1962 Japanese single digit seven segment display in terms of anode was more like the Philips DM70 / DM71 Magic Eye as the DM160 has a spiral wire anode. The Japanese seven segment VFD meant that no patent royalties needed to be paid on desk calculator displays as would have been the case using Nixies or Planaplex neon digits. In the UK the Philips designs were made and marketed by Mullard (almost wholly owned by Philips even before WWII). The Russian iv-15 VFD tube is very similar to the DM160. The DM160, DM70/DM71 and Russian iv-15 can like a VFD panel be used as triodes. The DM160 is thus the smallest VFD and smallest triode valve. The iv-15 is slightly different shape. Photo of DM160 and iv-15.

Of the three prevalent display technologies, VFD, LCD, and LED, the VFD was the first to be developed. It was used in early handheld calculators. LED displays displaced VFDs in this use as the very small LEDs used required less power, thereby extending battery life, though early LED displays had problems achieving uniform brightness levels across all display segments. Later, LCDs displaced LEDs, offering even lower power requirements.


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