 As with any multiplexing, there is a requirement to cycle through the in-use LEDs rapidly so that the persistence of the human eye perceives the display to be lit as a whole.Multiplexing can generally be seen by a strobing effect and skewing if the eye's focal point is moved past the display rapidly.The method, however, was known and utilized by various parties much earlier in the 1980s, and has been described in detail as early as in 1979 in a patent by Christopher W. Malinowski, Heinz Rinderle, and Martin Siegle of Department of Research and Development, AEG-Telefunken, Heilbronn, Germany for what they called a "three-state signaling system".