Real-time measurement of pressure inside field-emission displays

We present a method for nondestructive, real-time measurement of pressure inside sealed flat-panel field-emission displays. Analogous to an ion gauge, field-emitted electrons were used to ionize residual gases within the interelectrode region and the resulting ion current was measured. The procedure was calibrated in a vacuum chamber with known gas pressure. Next, we demonstrated the pressure measurement method inside sealed field-emission displays outfitted with spinning rotor gauge attachments for comparison. We found good correlation between the spinning rotor gauge measurement and the pressure measured by our method. In addition, we observed that the operation of the field-emission display resulted in a rapid drop in pressure similar to ion pumping effects observed in other vacuum electron tubes.