We propose a new plasma display panel cell structure, called the dual ignition discharge electrodes (DIDE) structure, with a long electrode gap to realize high luminous efficacy. The proposed DIDE structure has a long electrode gap $(200\ \mu\hbox{m} \sim 400\ \mu\hbox{m})$ but can nevertheless be driven at relatively low voltage because of auxiliary electrodes that are formed on the front panel. The discharge characteristic of the DIDE structure is much different from the characteristic of the conventional structure, and it was analyzed through infrared emission images that are taken by an intensified charge-coupled device camera and discharge current waveforms. These studies explain the unique discharge characteristics of the DIDE structure, which originate in the ignition discharge that is generated by its own electrode structure and driving waveform. The proposed long electrode gap and low voltage effect of the DIDE structure resulted in a very high luminous efficacy of 7.5 lm/W in a monochrome green test with Ne−Xe (12%) mixture at 400 torr.