A VFD or a Vacuum Fluorescent Display is a display device that was used on purchaser gadgets gear like car radios, video cassette recorders, and microwave ovens.

A VFD follows the principle of Cathodoluminescence which is much similar to that of the CRT (Cathode Ray Tube). The only difference is that they can be operated at a much lower potential difference. Each tube present in a VFD consists of an anode coated with a phosphor that is bombarded by electrons transmitted from the cathode fiber. In addition to that, each tube in a VFD has a mesh control grid.

A VFD produces an exceptionally splendid light with high contrast and can support display components of different hues. The standard illumination quantity for a VFD is around 640 cd/m². The VFDs providing high brightness operate at 4,000 cd/m² and that of the experimental components is as high as 35,000 cd/m² . The brightness of the display and the selection of color altogether influence the lifetime of the tubes. It ranges from as high as 30,000 hours for the most commonly produced green light to as low as 1,500 hours for a vivid red. In the past, cadmium was used as VFDs metal but now they are replaced by RoHS-complaint VFDs.

VFDs can display multi-segment Alpha Numeric characters or 7 segment numerals. By and by, there is little breaking point to the shape of the picture that can be shown: it depends exclusively on the state of phosphor on the anode(s).

The very first VFD was the DM160 made in 1959 by Philips. This was the single segment VFD. The 1^st multi-segment VFD was the 1967 Japanese single digit, 7 segment device. The displays started to get common on calculators as well as other purchaser gadgets gears. In the late 1980s, a huge number of units were made yearly.

Use:

Along with brightness, VFDs are inexpensive, rugged, and can be easily arranged to show a wide assortment of customized messages. In contrast to LCDs, VFDs are not restricted by the reaction time of adjusting liquid crystals. Thus, they can carry out their functions normally in cold temperatures. One of its biggest drawbacks of VFDs was that they used to consume a large amount of power than a simple LCD. This was viewed as a huge disadvantage for battery-worked gear like calculators and as a consequence, these VFDs ended up its use in devices that were given power using an AC source.

In the 1980s, VFDs found its use in automobiles for digital displays in odometers and speedometers. Their high brightness feature made them well suited for cars. From 1979 to the mid of 1980, VFDs were also used in portable electronic game units. VFDs also served a piece of good equipment for triode amplifiers.

This was all we have regarding Vacuum Fluorescent Display. Hope you like reading the article on it. Brands that manufacture them are Noritake, Matrix Orbital and Newhaven Display. Make sure to follow them using the links as provided.

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Unlike the CRT (Cathode Ray Tube), the LCDs (Liquid Crystal Display) are not able to produce light of its own. Thus it uses a backlight that provides illumination to it. Backlight provides illumination to the LCD from the back and side of the display panel. Backlight is generally used in small displays such as smartphones, LCD televisions, computer displays, wristwatches, etc.

For color screens, the LED backlighting comes under 2 categories. The first one is the RGB LED backlights and the second one is the white LED backlights.

• RGB LED backlights – The RGB LEDs are made up of red, blue and green LED which can be made to generate several color temperatures of white. RGB LED backlights are generally found in high display devices like HP EliteBook and HP DreamColor LP2480zx monitor. It has also found its use in Dell’s Studio series laptops. RGB LEDs are enabled to provide color gamut to screens. The 3 LED backlights can form a color spectrum that intently coordinates the color filters in the LCD pixels themselves. Using this technique, the filter passband is narrowed, as a result of which a narrow band of spectrum is allowed by each color component through the LCD. As there is a blockage of less amount of light, the efficiency of light is increased. In addition to that, the actual green, blue and red points can be displaced farther out such that more vivid colors can be formed by the display.

• White LED backlights – White LEDs are used frequently in the manufacture of desktop and notebook screens. A white LED is actually a blue LED with yellow phosphor to bring about the discharge of white light.

The LED backlights face several challenges as well. With the increase in the age of an LED, it's very hard to attain uniformity. As 3 different light sources are used i.e. red, green and blue, it means that with aging LED the white point of the display can get displaced at varied rates.  At higher temperature white LEDs faces blue shifts (from 3141K to 3222K for 10 degree Celsius to 80 degree Celsius). Power efficiency may also be kept as a point to note for LEDs.

To defend against the above-discussed challenges in white and RGB LED backlights, NDF Special Light Products has developed an LED technology known as 'advanced remote phosphor'. It uses blue pump LEDs in addition to a sheet having the printing of phosphorous luminescent materials. These are used in those LED applications that require a long life like Air Traffic Control displays, Cockpit display and medical displays.  The principle for this technology is similar to Quantum dots.

With time it is seen that notebook computer is using LED backlights at an immense rate. Since 2005 Sony is taking the help of LED backlights for its VAIO notebook. Asus, Apple, and Dell also made their own LED backlight notebooks by 2007. Today all screens of Apple use LED backlight, be it computer, laptops, etc.

Hope you liked the article on LED backlights. Brands that manufacture them are ELECTRONIC ASSEMBLY, Lumex and Newhaven Display. Make sure to follow them by the links as provided.

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