Active matrix is a type ofaddressing scheme used inflat panel displays. It is a method of switching individual elements of a flat panel display, known aspixels. Each pixel is attached to atransistor andcapacitor thatactively maintain the pixel state while other pixels are being addressed, in contrast with the olderpassive matrix technology in which each pixel must maintain its state passively, without being driven by circuitry.
Active matrix technology was invented byBernard J. Lechner atRCA,[1] usingMOSFETs (metal–oxide–semiconductor field-effect transistors).[2] Active matrix technology was first demonstrated as a feasible device usingthin-film transistors (TFTs) byT. Peter Brody, Fang Chen Luo and their team at the Thin-Film Devices department ofWestinghouse Electric Corporation in 1974, and the term was introduced into the literature in 1975.[3][4][5]
Given anm × n matrix, the number of connectors needed to address the display ism + n (just like in passive matrix technology). Each pixel is attached to a switch-device, whichactively maintains the pixel state while other pixels are being addressed, also preventingcrosstalk from inadvertently changing the state of an unaddressed pixel. The most common switching devices use TFTs, i.e. aFET based on either the cheapernon-crystallinethin-filmsilicon (a-Si),polycrystalline silicon (poly-Si), orCdSesemiconductor material.
Another variant is to use diodes or resistors, but neitherdiodes (e.g. metal insulator metal diodes), nor non-linear voltage dependentresistors (i.e.varistors) are currently used with the latter not yet economical, compared to TFT.
TheMacintosh Portable (1989) was perhaps the first consumer laptop to employ an active matrix panel.[citation needed] Since the decline ofcathode-ray tubes, as a consumer display technology, virtually all TVs, computer monitors and smartphone screens that useLCD orOLED technology employ active matrix technology.[6]