A. c. plasma display panel interrogating apparatus

Claim 2

Apparatus for interrogating an A.C. plasma panel wherein information storage is represented by the ionization condition of each of a plurality of gas discharge cells, said apparatus comprising means for applying to each cell a sustaining signal having an amplitude in the range between the extinction and ionizing levels whereby any cell activated to a lighted state as a consequence of the cell voltage momentarily exceeding the ionization level thereafter remains lighted under the influence of the sustaining signal, and means for applying an interrogate signal to prescribed cells of said plurality of cells, the interrogate signal having one component which effectively cancels the sustaining signal in at least one of said prescribed cells and an additional component which thereafter maintains the state of said one prescribed cell as it existed prior to application of the interrogate signal.

Claim 3

The apparatus of claim 1 wherein the additional component has an amplitude substantially the same as the sustaining signal and is further related thereto in one or two respects, one being a 180* phase shift from the sustaining signal and the other being a frequency which is a harmonic of the sustaining signal.

Claim 4

The apparatus of claim 1 wherein the panel includes respective sets of electrodes arranged transversely to one another on opposite sides of the cells and in superimposed relation therewith and further including an interrogate signal source, and means in said interrogate signal applying means for selectively connecting said interrogate signal source to individual electrodes of one set.

Claim 5

Apparatus for interrogating an A.C. plasma panel incorporating a plurality of gas discharge cells, comprising means for applying to each cell a sustaining signal having an amplitude intermediate the extinction and ionization levels of the cells, and means for simultaneously applying first and second components of an interrogate signal to first and second groups respectively of the plurality of cells, one cell being common to both groups and the interrogate signal being operative to maintain the voltage at the common cell above the extinction level while simultaneously reducing the voltage across the other cells of said groups below the extinction level.

Claim 6

Apparatus for interrogating an A.C. plasma panel incorporating a plurality of gas discharge cells, comprising means for applying to each cell a sustaining signal having an amplitude intermediate the extinction and ionization levels of the cells, and means for simultaneously applying first and second components of an interrogate signal to first and second groups respectively of the plurality of cells, one cell being common to both groups and the interrogate signal being operative to maintain the voltage at the common cell above the extinction level while simultaneously reducing the voltage across the other cells of said groups below the extinction level.

Claim 7

The apparatus of claim 4 wherein the means for applying the interrogate signals includes means for selectively applying the interrogate signal components to different groups such that the common cell can be selected as any one of the plurality of cells.

Claim 8

The apparatus of claim 4 further including means for sensing the output signal provided by said common cell in response to the interrogate signal.

Claim 9

The apparatus of claim 4 wherein the interrogate signal is of the same frequency and inverted in phase relative to the sustaining signal.

Claim 10

The apparatus of claim 4 wherein the one component of the interrogate signal includes a frequency which is a first harmonic of the sustaining signal frequency.

Claim 11

Apparatus for interrogating an A.C. plasma panel incorporating a matrix of gas discharge cells disposed between first and second sets of transversely oriented electrodes having cross-over points defining the location of the respective cells, said apparatus comprising an A.C. signal source coupled to the first and second sets of electrodes to establish a sustaining signal across each cell whereby any cell activated to a lighted stAte as a consequence of the cell voltage momentarily exceeding the ionization level thereafter remains lighted under the influence of the sustaining signal, and means for applying one component of an interrogate signal to a selected electrode of said first set of electrodes and applying an additional component of the interrogate signal to a selected electrode of said second set of electrodes simultaneously with the sustaining signal such that the cell located at the cross-over of the selected electrodes has a resultant signal applied thereto exceeding the extinction level of the cell whereas at the remaining cells associated with the selected electrodes the resultant signal applied to the cells is less than the extinction level.

Claim 12

Apparatus for interrogating an A.C. plasma panel incorporating a matrix of gas discharge cells disposed between first and second sets of transversely oriented electrodes having cross-over points defining the location of the respective cells, said apparatus comprising an A.C. signal source coupled to the first and second sets of electrodes to establish a sustaining signal across each cell whereby any cell activated to a lighted stAte as a consequence of the cell voltage momentarily exceeding the ionization level thereafter remains lighted under the influence of the sustaining signal, and means for applying one component of an interrogate signal to a selected electrode of said first set of electrodes and applying an additional component of the interrogate signal to a selected electrode of said second set of electrodes simultaneously with the sustaining signal such that the cell located at the cross-over of the selected electrodes has a resultant signal applied thereto exceeding the extinction level of the cell whereas at the remaining cells associated with the selected electrodes the resultant signal applied to the cells is less than the extinction level.

Claim 13

The apparatus of claim 9 wherein the interrogate signal is of the same frequency but inverted in phase relative to the sustaining signal and approximately twice the amplitude thereof.

Claim 14

The apparatus of claim 9 wherein the interrogate signal includes one frequency component equivalent to the sustaining signal frequency and other frequency component which is a first harmonic of the sustaining signal frequency.

Claim 15

The apparatus of claim 9 further including means for sensing the output signal provided by the selected cross-over cell in response to the interrogate signal.

Claim 16

The apparatus of claim 12 wherein each component of the interrogate signal is of substantially the same amplitude and frequency as the sustaining signal but phase shifted 180* therefrom.

Claim 17

The apparatus of claim 12 wherein each component of the interrogate signal includes respective subcomponents of half the amplitude of the sustaining signal, one subcomponent having a frequency equal to but inverted in phase relative to the sustaining frequency and another subcomponent, having a frequency which is a first harmonic of the sustaining frequency.