Active matrix electroluminescent display

1. An active matrix display, comprising an array of pixels ( 2 ) arranged in rows and columns,

wherein each pixel includes:

a display element ( 22 ) for producing a visual output when the display element is driven with a constant current;

drive circuitry for controllably driving a substantially constant current through the display element, the drive circuitry including a two transistor inverter ( 14 , 30 ) having an input node ( 28 ) and a drive node ( 20 ),

wherein the common node output of the inverter is connected, directly or indirectly, to supply or control the current passing through the corresponding display element;

wherein the active matrix display further comprises a plurality of data lines ( 10 ) for carrying a digital signal,

a plurality of address lines ( 8 );

wherein the drive circuitry of each pixel comprises an input mode ( 28 ) and an address transistor ( 12 ) for inputting a digital signal to the input node, the address transistor being connected to one of the address lines ( 8 ), one of the data lines ( 10 ), and the input node ( 28 ); and

wherein a single common line ( 50 , 60 ) constitutes a power line of one row and the address line of an adjacent row.

2. An active matrix display according to claim 1 wherein the display element ( 22 ) is an organic light emitting diode.

3. An active matrix display according to claim 1 ,

wherein:

the drive circuitry includes a drive transistor ( 16 ) connected between a first power ( 4 ) line and a drive node ( 20 ) to drive the display element ( 22 ), the drive transistor being controlled for inverting operation by the input node ( 28 ); and

the inverter ( 30 ) is a feedback inverter having its input connected to the drive node and its common node output connected to the input node.

4. An active matrix display according to claim 3 further comprising a discharge transistor ( 18 ) of opposite conductivity type to the drive transistor ( 16 ) connected between the drive node ( 20 ) and a second power line ( 6 ), the discharge transistor and the drive transistor ( 16 ) forming an inverter ( 14 ).

5. A active matrix display according to claim 1 , wherein the common node ( 20 ) is connected to drive the display element and the input of the inverter is connected to the input node.

6. An active matrix display according to claim 1 wherein the address transistor is a p-type transistor ( 12 ), and the common line ( 50 ) is the high power line of one row and the address line of an adjacent row.

7. An active matrix display according to claim 1 wherein the address transistor ( 12 ) is an n-type transistor, and the common line ( 60 ) is the low power line of one row and the address line of an adjacent row.