Liquid Crystal Displays (LCDs)

Arduino circuits can take inputs from sensors or a human interaction device such as a switch or a keypad. They then process the data and either send it to a processor for analysis or to a database to store. In many case, the data also needs to be displayed for a human to read. There are a few types of electronic displays available for use with Arduino boards, the most commonly used one being liquid crystal displays (LCDs).

An LCD is a flat-panel display that uses the light-modulating properties of liquid crystals. Liquid crystals do not emit light directly, instead of that use a backlight or reflector to produce images in color or monochrome. LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images with low information content, such as preset words, digits, and seven-segment displays (as in a digital clock). They use the same basic technology, except that arbitrary images are made up of several tiny pixels, while other displays have a smaller number of pixels.

LCDs can either be on (positive) or off (negative). For example, a character-positive LCD with a backlight will have black lettering on a background that is the backlight color, and a character-negative LCD will have a black background with the letters being of the same color as the backlight.

LCDs are used in various applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in portable consumer devices, such as digital cameras, watches, calculators, and mobile telephones, including smartphones. LCD screens are also used on consumer electronics products, such as DVD players, video game devices, and clocks.

LCDs come in various sizes, with multiple rows and columns. A single character is displayed on one cell (intersection of column and row), thus allowing up to 32 characters to be displayed on the screen at one time. Of course, the amount of data you can display on an LCD is far lesser than what you can output on your computer.