ECHO PREVENTION CIRCUIT

WIPO Patent Application WO/2004/086814

A1

An echo prevention circuit is configured in such a manner that in a telephone receiving part (11) of one communication device (1), second amplifiers (A2,A3) connected to respective speakers (SP1,SP2) are provided separately from an amplifier circuit (A1) and that a distributing circuit (12) is provided for distributing, to these second amplifiers, the magnitude of a telephone reception signal voltage, which has been supplied from a transmission system (18) and amplified by the amplifier, in an unbalanced manner at any time such that an output voltage of a microphone (MIC1) is minimum. This prevents echo effect from occurring between the telephone receiving and transmitting parts of each of two communication devices (1,2), so that the telephone receiving and transmitting parts can be located at the same place or close places and a stable two-way telephone communication can be realized.

JP2008211526	VOICE INPUT/OUTPUT DEVICE AND VOICE INPUT/OUTPUT METHOD
JP2018137531	GAIN SETTING DEVICE, LOUDSPEAKER SYSTEM, GAIN SETTING METHOD AND PROGRAM
JP3067409	[Title of Invention] Howling Prevention Processor

TANIGUCHI YASUTOSHI (JP)

PCT/JP2004/003495

October 07, 2004

March 16, 2004

Click for automatic bibliography generation  

NAP ENTPR CO LTD (JP)
SCHOOL JURIDICAL PERSON OF FUK (JP)
TANIGUCHI YASUTOSHI (JP)

H04R3/02; H04B3/23; H04M1/58; H04M1/60; H04M3/56; H04M9/08; H04M3/00; (IPC1-7): H04R3/02; H04M1/58; H04M3/56

JPH11225391A	1999-08-17
JPH05265470A	1993-10-15
JP2000261882A	2000-09-22
JPS58114555A	1983-07-07
JPH03274894A	1991-12-05
JPH0591583A	1993-04-09
JP2003174699A	2003-06-20
JPS6468006A	1989-03-14

Igarashi, Kazutoshi (K.S Bldg. 5, Kojimachi 4-chom, Chiyoda-ku Tokyo 83, JP)

View/Download PDF      PDF Help

Previous Patent: SPEAKER SYSTEM SOUND WAVE GUIDE STRUCTURE AND HORN SPEAKER

Next Patent: MINIATURISED ELECTROACOUSTIC TRANSDUCER