Seven-segment display

In 1910, a seven-segment display illuminated by incandescent bulbs was used on a power-plant boiler room signal panel.

[12][13] The seven-segment pattern is sometimes used in posters or tags, where the user either applies color to pre-printed segments, or applies color through a seven-segment digit template, to compose figures such as product prices or telephone numbers.

Unlike LEDs, the shapes of elements in an LCD panel are arbitrary since they are formed on the display by photolithography.

However, the easy recognition of seven-segment displays, and the comparatively high visual contrast obtained by such displays relative to dot-matrix digits, makes seven-segment multiple-digit LCD screens very common on basic calculators.

Using a restricted range of letters that look like (upside-down) digits, seven-segment displays are commonly used by school children to form words and phrases using a technique known as "calculator spelling".

For gasoline price totems and other large signs, electromechanical seven-segment displays made up of electromagnetically flipped light-reflecting segments are still commonly used.

[14] In USSR, the first electronic calculator "Vega", which was produced from 1964, contains 20 decimal digits with seven-segment electroluminescent display.

Some of these integrated displays incorporate their own internal decoder, though most do not: each individual LED is brought out to a connecting pin as described.

[17] Often in pocket calculators the digit drive lines would be used to scan the keyboard as well, providing further savings; however, pressing multiple keys at once would produce odd results on the multiplexed display.

The digit changes at a high enough rate that the human eye cannot see the flashing (on earlier devices it could be visible to peripheral vision).

In most applications, the segments are of nearly uniform shape and size (usually elongated hexagons, though trapezoids and rectangles can also be used); though in the case of adding machines, the vertical segments are longer and more oddly shaped at the ends, to try to make them more easily readable.

[18][16] A single byte can encode the full state of a seven-segment display, including the decimal point.

The following are some real world English word examples seen on actual electronic equipment (first line appeared on some CD players): There are also fourteen- and sixteen-segment displays (for full alphanumerics); however, these have mostly been replaced by dot matrix displays.