Seven-segment displays are very common and have been for quite some time. They can be found everywhere from the price signs at gas stations to the display on your microwave oven to digital wristwatches. LED seven-segment displays have become very popular in consumer electronics, mainly because of their low power usage, ease of production and cost effectiveness. Seven-segment LED displays, like all technology, have advantages and disadvantages.
Light emitting diodes (LEDs) are extremely cheap. Diodes are one of the most simple electrical components, and they are extremely easy to make. A trip to your local electronics store will reveal packages of hundreds of LEDs for only a few dollars.
Seven-segment displays are extremely simple electronic circuits. A simple seven-segment display circuit consists of four input leads; a BCD chip, which contains logic gates to translate the four leads into seven binary signals, or integrated circuit chip; and the seven-segment display itself. Most seven-segment displays are capable of displaying all 16 hexadecimal values (1 through 9 and A through F).
Since the seven-segment circuit is so simple, there is a decreased risk of circuit malfunction due to component failure. Seven-segment LED displays are used in a wide range of environments from very hot to well below freezing. As there is no liquid inside the unit to freeze, as there is in LCD displays, an LED display can operate at very low temperatures.
LED displays in general are extremely efficient. Diodes dissipate very little energy. Light-emitting diodes emit slightly more energy than a standard diode in order to produce the photons (light) that you see, but the voltage drop across a typical LED is so small that it is negligible. Because of this high efficiency, many electronics makers favour LED technology over LCD technology because it lowers power supply requirements and reduces the cost of using devices.
Most seven-segment displays are limited to displaying the 16 hexadecimal characters. Some can display only the numbers 0 through 9. Although LED technology exists to display more than this, seven-segment displays are limited to possible binary combinations of the four input leads, for a total of 16. Integrated circuit technology can increase this somewhat, but there are still a limited number of combinations for the seven segments on the display.
Because LEDs are so cheap to produce and so easy to make, many manufacturers have sprang up over the past several decades. There is very little regulation in terms of making LEDs, excluding the environmental regulations regarding pollution, and it is therefore easy to find a manufacturer that produces substandard LEDs. The only way to know for sure if a manufacturer produces quality LEDs is by recommendation or buying and testing the product yourself.