Handsfree communication apparatus

• US 5,546,458 A
• Filed: 03/02/1995
• Issued: 08/13/1996
• Est. Priority Date: 05/18/1994
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Iwami, Akiko
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): SAINT SURIN, JACQUES M
• Application Number:
  US08/397,835
• Time in Patent Office: 530 Days
• Field of Search: 379/390, 379/387, 379/395, 379/419, 379/433, 379/58, 379/57, 381/92, 381/94
• US Class Current: 379/392.01
• CPC Class Codes: H04M 1/19 Arrangements of transmitters, receivers, or complete sets to prevent eavesdropping, to attenuate local noise or to prevent undesired transmission; Mouthpieces or receivers specially adapted therefor circuit arrangements for preventing eavesdropping H04M1/68; telephone cabinets E04H1/14
• CPC Class Codes: H04M 1/6041 Portable telephones adapted for handsfree use
• CPC Class Codes: H04M 1/6075 adapted for handsfree use in a vehicle H04M1/6058 takes precedence; arrangements for holding telephones in a vehicle B60R11/0241
• CPC Class Codes: H04M 9/08 Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A handsfree communication apparatus utilizing a plurality of microphones to allow simultaneous communication by a plurality of persons. The plurality of microphones are separately provided apart from one another. An amplifier section (or a noise canceller) includes a plurality of operational amplifiers for signal amplification individually corresponding to the plurality of microphones, and differential amplifier circuit for executing a differential amplification. Through the differential amplification, simultaneously input noise components are canceled out and reduced, and at the same time speech components are extracted.

Claims

1. A handsfree communication apparatus intended to be connected to a wireless telephone set, comprising:

a plurality of microphones individually provided apart from one another and being spaced apart and positioned with respect to each other for receiving separate speech inputs from different persons for allowing a plurality of persons to take part in simultaneous handsfree communication;

a plurality of amplifiers each for amplifying output signals from said plurality of microphones; and

a speech extraction circuit for receiving output signals from said plurality of amplifiers to cancel out common signal components among the output signals.

2. A handsfree communication apparatus according to claim 1, wherein

said speech extraction circuit includes differential amplifier for executing a differential amplification between output signals from said plurality of amplifiers.

3. A handsfree communication apparatus according to claim 2, wherein

said differential amplifier is comprised of an operational amplifier.

4. A handsfree communication apparatus according to claim 1, wherein

said speech extraction circuit includes one or a plurality of operational amplifiers each serving as a differential amplifier, the number of said operational amplifiers depending on the number of said plurality of microphones.

5. A handsfree communication apparatus according to claim 4, wherein

said plurality of operational amplifiers are connected with one another in a tournament arrangement, and wherein

among said plurality of operational amplifiers, one positioned at the final stage in said tournament arrangement provides as its output a noise-canceled speech signal.

6. A handsfree communication apparatus according to claim 1, further comprising:

a switch section for individually changing over on/off actions of said plurality of microphones.

7. A handsfree communication apparatus intended to be connected to a wireless telephone set installed in a vehicle, said communication apparatus comprising:

a plurality of microphones individually provided apart from one another and being spaced apart and positioned with respect to each other for receiving separate speech inputs from different persons for allowing a plurality of persons to take part in simultaneous handsfree communication;

a plurality of amplifiers each for amplifying output signals from said plurality of microphones; and

a speech extraction circuit for inputting output signals from said plurality of amplifiers to cancel out noise components common among the output signals and to extract speech components different among the output signals.

8. A handsfree communication apparatus according to claim 7, wherein

said speech extraction circuit includes a differential amplifier for executing differential amplification between output signals from said plurality of amplifiers.