Passive matrix addressing

Passive matrix addressing is an addressing scheme used in early liquid crystal displays (LCDs). It is a matrix addressing scheme, meaning that only m + n control signals are required to address an m × n display. A pixel in a passive matrix must maintain its state without active driving circuitry until it can be refreshed again.

The signal is divided into a row or select signal and a column or video signal. The select voltage determines the row that is being addressed and all n pixels on a row are addressed simultaneously. When pixels on a row are being addressed, a Vsel potential is applied, and all other rows are unselected with a Vunsel potential. The video signal or column potential is then applied with a potential for each m columns individually. An on-switched (lit) pixel corresponds to a Von, an off-switched (unlit) corresponds to a Voff potential.[1]

The potential across pixel at selected row i and column j is

Vij=Vsel−Von|off

and

Vij=Vunsel−Von|off

for the unselected rows.[2]

This scheme has been expanded to define the limits of this type of addressing typical LCDs.[3][4]

Passive matrix addressed displays, such as ferroelectric liquid crystal displays, do not need the switch component of an active matrix display, because they have built-in bistability. Technology for electronic paper also has a form of bistability. Displays with bistable pixel elements are addressed with a passive matrix addressing scheme, whereas TFT LCD displays are addressed using active addressing.

## See also

* Active matrix addressing
* Pixel geometry
* Liquid crystal display

## References

1. ↑ Wild, Peter J. "First-Hand Histories: Liquid Crystal Display Evolution - Swiss Contributions". Engineering and Technology History Wiki. ETHW. http://ethw.org/First-Hand:Liquid_Crystal_Display_Evolution_-_Swiss_Contributions#Venture:_BBC_&_ROCHE. Retrieved June 30, 2017.
2. ↑ P. M. Alt, P. Pleshko Scanning limitations of liquid-crystal displays, IEEE Trans. Electron Devices, vol. ED-21, pp. 146–155, Feb. 1974.
3. ↑ J. Nehring, A. R. Kmetz: Ultimate limits for matrix addressing of RMS-responding liquid-crystal displays. IEEE Transactions on Electron Devices. Vol. 26, issue 5, pp. 795–802, May 1979.
4. ↑ T. N. Ruckmongathan, V. Arun, Babu Hemanth Kumar: Line-by-Line Addressing of RMS Responding Matrix Displays With Wavelets. Journal of Display Technology. Vol. 3, issue 4, pp. 413–420 December 2007.

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