Active matrix addressing

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Active matrix addressing is an addressing scheme used in video displays. Given a n × m matrix, the number of connectors needed to address the display is n + m.

Each pixel is attached to a switch-device, which actively maintains the pixel state while other pixels are being addressed, which also prevents crosstalk from inadvertently changing the state of an unaddressed pixel. The most common switching devices are Thin Film Transistors (TFT), i.e. a FET based on either the cheaper non-crystalline thin-film silicon (a-Si), polycrystalline silicon (poly-Si), or CdSe semiconductor material. The latter is rarely used any longer in favour of the former two.

Another variant is to use diodes or resistors, but neither diodes (e.g. Metal insulator metal diodes), nor non-linear voltage dependent resistors (i.e. varistors) are currently used. The latter of which is not yet economical when compared to TFT.

See also: passive matrix addressing, pixel geometry, LCD