“Despite the fact that it’s been around for a long time, the vacuum fluorescent display (VFD) is still a very attractive type of display. It’s viewable in bright light but is easily dimmable for comfortable viewing in the dark. It has the versatility of a Liquid Crystal Display in that its illuminated elements can be formed into any shape and it doesn’t need a backlight.
This photo shows three typical types of VFD. The top two have the familiar 7-segment numeric digits and include some extra elements specific to the device they’re intended for. The one on the right seems to be for a clock radio with timer and sleep functions. The one on the left is probably be for a temperature-controlled device. I picked them both up off eBay for less than 5 UKP each. Despite their obvious differences, they have one thing in common: They are “bare” displays without any control circuitry.
The display at the bottom of the photo is different. Instead of the 7-segments to form the characters, it uses a 7x5 matrix of “pixels” for each character and is, therefore, alpha-numeric. It’s identical in behaviour to a 16x2 LCD alpha-numeric display. In fact, the one shown here comes equipped with all the necessary voltage and control logic and is fully compatible with the Arduino’s Liquid Crystal Display Library. It’s also about six times more expensive than the top two!”