| 摘要 |
PURPOSE:To decrease the number of buttons for selecting a function by detecting a signal of a specified frequency of the surface of a function button, connecting it to a tuning circuit, and assigning a different function to the function button in accordance with whether a detecting output exists or not, by a controlling circuit. CONSTITUTION:When a button 19 is depressed by an electric conductor 23 of a telephone receiver 21, a voltage of a prescribed value is applied to an input port Q through a switch S of a key matrix circuit 11 from an output port P of a controlling circuit 11, and a depression of the button is detected. Also, from an oscillating circuit 15 which has been started by a control signal of the controlling circuit 11, an oscillating signal is inputted to a tuning circuit 17 through the electric conductor 23 of the telephone receiver 21 and through a switch S and a capacitor C of a key matrix circuit 16. The controlling circuit 11 analyzes the voltage of the prescribed value which has been inputted to the input port Q and the oscillating signal which has been inputted to an input port R, and discriminates them from the case when the button 19 has been depressed by a hand H, two kinds of functions can be selected by one button and the number of buttons can be decreased. In this way, the design aspect and the operability are improved.
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