PURPOSE: To reduce the number of components, reduce cost, and save space without damaging operating capability of an operating switch by recognizing individual signals as different signals not as single receiving when a plurality of signals are received at the same time.

CONSTITUTION: A concentration up key 11, a concentration down key 12, and an AE key 10 are arranged as a mechanical switch concerning concentration adjustment in an operation panel 1, and a concentration up switch 21 and a concentration down switch 22 are arranged as an electric switch (contact surface). A foot of the AE key 10 extends right and left directions, a right side tip 10a positions in the upper part of a switch contact surface 21 at the tip of the foot of the key 11, and a left side tip 10b positions in the upper part of a switch contact surface 22 at the tip of the foot of the key 12. When the key 10 is pushed, the switches 21/22 are pushed, and a plurality of signals are dispatched at the same time. In this case, it is recognized that switching from a manual concentration adjusting mode to an automatic concentration adjusting mode is instructed. Thereby, the number of switch components is reduced without damaging operating capability.