Electronic scan methods for plasma displays

In an electronically powered threshold device light source of the type producing visible light from those segments of a two-sided interface zone therein across which a voltage difference in excess of a threshold value exists, an improvement for producing light from selected segments of the interface zone in a preselected order responsive to a control signal, and comprising:

• a. a conductor adjacent a first side of the interface zone, and having first and second points adjacent first and second segments of the interface zone respectively;
• b. an impedance adjacent a second said of the interface zone generally spaced across the interface zone from the first side, having first and second points adjacent the first and second segments respectively, and having appreciable impedance between its first and second points;
• c. a first voltage source of preselected value connected between the first and second points of the impedance;
• and
• d. a second voltage source connected between the conductor and the impedance, whose voltage output varies responsive to the control signal from a value creating a voltage difference between the first points of the conductor and the impedance at least equal to the threshold value, to a value simultaneously creating voltage differences between the first points of the conductor and the impedance and between the second points of the conductor and the impedance both at least equal to the threshold value.