At a wire crossover portion, extension wires, which are electrically connected
to scanning electrode connecting wires, extend so as to cross over the other scanning
electrode circuitous wires without having contact with the other scanning electrode
circuitous wires and to be electrically connected to the corresponding scanning
electrode circuitous wire. Thus, it is possible to ensure routes for leading out
respective scanning electrodes without having contact with other wires, and it
is possible to collectively apply a voltage for an aging treatment to the respective
routes. Portions, where the extension wires extend so as to cross over, are formed
in the same step as a step for forming a cathode layer as the scanning electrodes.