I think the PLANON was actually invented in 1998 and discontinued recently. I have read this in the history of Osram Disply/Optic. Here is the link:
www.osram.com/osram_com/Professionals/DisplayOptic_Lighting/DisplayOptic_History/index.html . under the invention of PLANON in 1998 they writted that the product discontinued. also the use of xenon instead of mercury slow the degeneration of the phosphor because there is no mercury absorbed. and the electrodes in this lamp is preservesd because it is not in contact to the discharges therefore improves the lumen maintenance.