| 摘要 |
PURPOSE:To relieve trouble of a call tone given to a surrounding party by providing a sound quantity control circuit to the receiver so as to reduce a tone volume of a ring tone generated from a speaker stepwise or continuously. CONSTITUTION:A radio signal received by an antenna 1 is sent to a control section 4 through an RF section 2 and a decode section 3. When the control section 4 detects the number of a concerned station, call is made by sound, light, character display or the like. An output from a ring tone oscillator OSC 8 generating a call tone signal is inputted to a transistor(TR) Q1 and fed to a speaker 7 via a variable resistor circuit comprising TRs Q2-Q4 and resistors R1-R3. A control signal according to a preset program is outputted from output DTO-DT2 of the control section and the resultant resistance of the resistors R1-R3 is stepwise changed by applying on/off control to the TRs Q2-Q4 so as to vary the sound pressure of the speaker 7 thereby reducing stepwise the call tone. |
