US 5,396,550 AGranted

Radio and land-line telephones with hands-free operation

AssigneeSamsung Electronics Co., Ltd.

InventorKyoung-Jun Kim

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Abstract

Disclosed are hands-free land-line and radio telephones comprising a public telecommunication network connection part for transmitting a signal from the transmission signal input terminal to the public telecommunication network connection terminal and a reception signal from the public telecommunication network connection terminal to the reception signal output terminal, a first voltage controlled attenuator for controlling an output of the microphone by a given loss corresponding to a first control voltage level, a second voltage controlled attenuator for controlling a reception signal by a given loss corresponding to a second control voltage input level, a first detection circuit for generating a rectified voltage proportional to a magnitude of an input audio signal by rectifying an output signal of the microphone, a second detection circuit for generating a rectified voltage proportional to a magnitude of an input audio signal by rectifying an output signal of the reception signal output terminal, a control voltage output means for generating a gradient voltage signal corresponding to the difference of a transmission signal and a reception signal, and an inverting amplifier for inverting an output of the control voltage output means, wherein attenuation rates of the first and the second voltage controlled attenuators are controlled automatically in a complementary fashion, by the difference between a transmission signal and a reception signal.

Claims26

Dependent claims

A hands-free telephone comprising:

a microphone for converting an input audio signal into an electric signal;
a speaker for converting an electric signal into an output audio signal;
a public telecommunication network connection part installed between a public telecommunication network connection terminal, a transmission signal input terminal and a reception signal output terminal to transmit a transmission signal from said transmission signal input terminal to said public telecommunication network connection terminal, and a reception signal from said public telecommunication network connection terminal to said reception signal output terminal;
a first voltage controlled attenuator installed between said microphone and said transmission signal input terminal to control an output of said microphone by a given gain corresponding to a level of a first control voltage;
a second voltage controlled attenuator installed between said speaker and said reception signal output terminal to control the reception signal by a given gain corresponding to a level of second control voltage;
a first detection circuit for rectifying said output of said microphone to generate a rectified voltage proportional to a magnitude of said input audio signal;
a first output path for providing a first output signal exhibiting a plurality of states determined by said rectified voltage from said first direction circuit:
a second detection circuit for rectifying said reception signal to generate a rectified voltage proportional to a magnitude of said reception signal;
control voltage output means for comparing and amplifying outputs of said first detection circuit and said second detection circuit corresponding to a difference between said transmission signal and said reception signal, to generate a gradient voltage smaller than a given voltage in case of said transmission signal being larger than said reception signal and to generate a gradient voltage larger than said given voltage in case of said transmission signal being smaller than said reception signal, and for applying said gradient voltage to said second voltage controlled attenuator as said second control voltage;
a gate for applying a control signal of a first one of said plurality of states to said first and second voltage controlled attenuators when both outputs of said first output path and said second detection circuit exhibit a same one of said plurality of states:
and
an inverting amplifier coupled between an output port of said control voltage output means and said first voltage controlled attenuator, for inverting said control signal transmitted to said first voltage controlled attenuator so that the attenuation rate of said first and second voltage controlled attenuators are controlled automatically according to the amount of the difference between said transmission signal and said reception signal.

9 more elements

A hands-free telephone for transmitting a transmission signal and receiving a reception signal, comprising:

first voltage controlled attenuation means for attenuating an audio input signal in response to a first control voltage signal to generate said transmission signal;
second voltage controlled attenuation means for attenuating said reception signal in response to a second control voltage signal to generate an audio output signal;
first detection means for detecting and rectifying said audio input signal to generate a first rectified voltage signal;
second detection means for detecting and rectifying said reception signal to generate a second rectified voltage signal;
control voltage output means for comparing said first and second rectified voltage signals to generate said first and second voltage control signals, with said first and second voltage control signals based on a difference between said first and second rectified voltage signals and being complementary to each other;
rectifying means for rectifying said first voltage control signal and said second voltage control signal received from said control voltage output means;
and
means for generating third and fourth voltage control signals having a first state in response to said first and second rectified voltage signals having a second state, said third and fourth voltage control signals being combined with said first and second voltage control signals to control attenuation of said audio signal and said reception signal.

5 more elements

A hands-free telephone system, comprising:

microphone, responsive to audible sounds, for converting the audible sounds into first electrical signals:
a speaker, responsive to second electrical signals, for converting the second electrical signals into audible sounds;
first attenuator means for controlling attenuation of said first electrical signals from said microphone in dependence upon a first voltage control signal to generate transmission signals;
means, connected to communication lines, for transmitting said transmission signals to communication lines and receiving reception signals from the communication lines;
second attenuator means for controlling attenuation of said reception signals to said speaker in dependence upon a second voltage control signal to generate said second electrical signals;
first detector means for detecting and rectifying said first electrical signals to generate a first detected signal having a first voltage proportional to a magnitude of said first electrical signals;
second detector means for detecting and rectifying said reception signals to generate a second detected signal having a second voltage proportional to a magnitude of said reception signals;
noise detector means for generating resultant a signal by enabling transmission of one of a third voltage and said first detected signal exhibiting said first voltage, in dependence upon detection of noise from said first detected signal:
and
voltage control generator means for generating said first and second voltage control signals to control attenuation of said first electrical signals from said microphone and said reception signals to said speaker, in dependence upon a comparison of said resultant signal and said second detected signal:
said voltage control generator means comprising:
means for logically combining said resultant signal and said second detected signal to generate a logic signal;
means for comparing said resultant signal and said second detected signal having said second voltage to generate a compared signal;
means for inverting said compared signal to generate an inverted signal;
means for generating a first combined signal by combining said inverted signal and said logic signal, and for rectifying the first combined signal to generate said first voltage control signal for controlling attenuation of said first electrical signals from said microphone;
and
means for generating a second combined signal by combining said compared signal and said logic signal and rectifying the second combined signal to generate said second voltage control signal for controlling attenuation of said reception signals to said speaker.

14 more elements

A hands-free telephone system, comprising:

microphone, responsive to audible sounds, for converting the audible sounds into first electrical signals:
a speaker, responsive to second electrical signals, for converting the second electrical signals into audible sounds:
first attenuator means for controlling attenuation of said first electrical signals from said microphone in dependence upon a first voltage control signal to generate transmission signals:
means, connected to communication lines, for transmitting said transmitting said transmission signals to the communication lines and receiving reception signals from the communication lines;
second attenuator means for controlling attenuation of said reception signals to said speaker in dependence upon a second voltage control signal to generate said second electrical signals:
first detector means for detecting and rectifying said first electrical signals to generate a first detected signal having a first voltage proportional to a magnitude of said electrical signals;
second detector means for detecting and rectifying said reception signals to generate a second detected signal having a second voltage proportional to a magnitude of said reception signals;
noise detector means for generating a resultant signal by enabling transmission of one of a third voltage and said first detected signal exhibiting said first voltage, in dependence upon detection of noise from said first detected signal;
and
voltage control generator means for generating said first and second voltage control signals to control attenuation of said first electrical signals from said microphone and said reception signals to said speaker in dependence upon a comparison of said resultant signal and said second detected signal;
said voltage control generator means comprising:
a NAND gate for logically combining said resultant signal and said second detected signal to generate a first operational signal;
an operational amplifier for comparing said resultant signal and said second detected signal having said second voltage to generate a second operational signal;
an inverter for inverting said second control signal to generate an inverted signal;
a first diode interposed between said inverter and said first attenuator means;
a second diode interposed between said gate and said second attenuator means;
a third diode interposed to convey said first operational signal to said first attenuator means;
and
a fourth diode interposed to convey said second operational signal to said second attenuator means;
a first rectifier for rectifying said inverted signal and said first operational signal via said third diode to generate said first voltage control signal for controlling attenuation of said electrical signals from said microphone;
and
a second rectifier for rectifying said first operational signal and said second operational signal via said fourth diode to generate said second voltage control signal for controlling attenuation of said reception signals to said speaker.

19 more elements

Dependencies are inferred from the claim text.