Patent ID: 7652433

Claim:
A method for prolonging the life span of a planar light source generating apparatus, comprising: applying a DC voltage to a plurality of cathodes of the planar light source generating apparatus, wherein the cathodes have a plurality of emitting layers formed thereon; applying a ground potential to a plurality of gates of the planar light source generating apparatus, wherein the gates have a plurality of emitting layers formed thereon; connecting a current sensor to a conductive reflection layer of an anode of the planar light source generating apparatus; obtaining a maximum electron current density shown by the current sensor once the planar light source generating apparatus starts to operate; switching the cathodes' external power source from the DC voltage to the ground, and the gates' external power source from the ground to the DC voltage, when the current sensor detects the current density dropping to a first predetermined percentage of the maximum current density; switching the cathodes' external power source from the ground to the DC voltage, and the gates' external power source from the DC voltage to the ground, when the current density detected by the current sensor is attenuated to a second predetermined percentage of the maximum value; and repeating the foregoing steps until the current density of the emitting layer disposed on the gates or the cathodes is attenuated to 50% of the maximum electron current density so that no switching between the external power sources is carried out, wherein the first predetermined percentage and the second predetermined percentages are selected from one of a group values consisting of any percentage greater than 50%.