Patent ID: 7119765

Claim:
A circuit for producing light at a plurality of gray scale values, the circuit comprising: a photoluminescence quenching device (PQD) having an anode and a cathode, and defined as a pixel, the PQD being connected to a driving circuit at a crossing of a scan line and a data line, the driving circuit comprising: an activation transistor having a control electrode connected to the scan line and an input electrode connected to the data line, the activation transistor being turned on in response to potential of the scan line, and, when turned on, outputting potential of the data line; and a driver transistor having a control electrode connected to an output electrode of the activation transistor, the driver transistor being connected between a reference voltage terminal of the circuit and the PQD and, when the activation transistor is turned on, applying to the anode of the PQD the potential that is applied to the reference voltage terminal, according to the potential of the data line, wherein in an emissive mode of operation of the PQD, when the driver transistor is turned on, a forward voltage is applied between the anode and the cathode of the PQD so that the PQD emits light according to a gray scale value, and in a re-emissive mode of operation of the PQD in which the PQD can produce light by photoluminescence, when the driver transistor is turned off, a reverse voltage is applied between the anode and the cathode of the PQD to produce light according to a gray scale value.