Patent ID: 7626337

Claim:
A protective film disposed on surfaces of sustaining electrode of a plasma display panel, wherein the plasma display panel includes a first panel and a second panel, a scanning electrode and a sustaining electrode being disposed on a surface of the first panel while being insulated from one another, and an address electrode being disposed on a surface of the second panel and a fluorescent film being disposed on the address electrode, wherein an inert gas is charged in between the first and second panels, and by applying voltage between the address electrode and the scanning electrode, a write discharge occurs, and by applying AC voltage between the scanning electrode and the sustaining electrode, a sustaining discharge is brought about, and ultraviolet rays discharged from the plasma which is generated by the sustaining discharge are irradiated to the fluorescent film, thereby being emitted, the protective film comprising SrO and CaO, wherein the CaO content is at least 60 mol % and at most 90 mol %, and when AC voltage is applied between the scanning electrode and the sustaining electrode, secondary electron is discharged and the sustaining discharge occurs.