Apparatus for controlling an operational panel

An apparatus for controlling an operational panel on which keyboards or change over switches are arranged, comprising:

• switches arranged at each intersection of a switch matrix;
• a driving circuit for transferring driving signals to common lines of the switch matrix;
• a receiving circuit for receiving switch input signals via said data lines of said switch matrix;
• switch discriminating elements for transferring switch discriminating signals to said receiving circuit via switch discriminating data lines, said switch discriminating signals indicating whether said switches should sound a buzzer when receiving said driving signals arranged on each of said common lines;
• an ON/OFF state discriminating means for discriminating the ON/OFF state of said switches after reading the states of said driving signals and said switch input signals;
• a buzzer driving discriminating means for discriminating whether said buzzer should be sounded by reading said switch discriminating signals via said switch discriminating elements when any of said switches are determined to be in an ON state by said ON/OFF state discriminating means;
• and
• a buzzer driving means for sounding said buzzer when said buzzer driving discriminating means determines that said buzzer should be sounded,
• wherein said buzzer sounds when said switches arranged at each intersection of said switch matrix are flat key type switches, and does not sound said buzzer when they are rotary switches or change over switches and wherein said switch discriminating elements comprise diodes when said switch discriminating elements are arranged on said common lines where switches for sounding said buzzer are arranged, while said common lines and said switch discriminating data line are cut off when said switch discriminating elements are arranged on said common lines where switches for not sounding said buzzer are arranged.