(19)
(11) EP 0 966 178 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
21.03.2001 Bulletin 2001/12

(43) Date of publication A2:
22.12.1999 Bulletin 1999/51

(21) Application number: 99304612.7

(22) Date of filing: 14.06.1999
(51) International Patent Classification (IPC)7: H04R 1/00, H04R 1/10, G10K 11/178
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 18.06.1998 JP 17186598

(71) Applicants:
  • MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
    Kadoma-shi, Osaka (JP)
  • Riko, Yasuhiro
    Yokohama-shi (JP)

(72) Inventors:
  • Yasuno, Yoshinobu
    Tokyo (JP)
  • Riko, Yasuhiro
    Yokohama-shi (JP)

(74) Representative: Hallybone, Huw George 
CARPMAELS AND RANSFORD 43 Bloomsbury Square
London WC1A 2RA
London WC1A 2RA (GB)

   


(54) Digital electro-acoustic transducer


(57) A digital electro-acoustic transducer for improving the speech quality of sound under noisy circumstances is disclosed. A plurality of sound generating units A (22) constituted by electrostatic electro-acoustic transducers (condenser earphones) and a sound receiving unit B (23) constituted by an electrostatic acousto-electric transducer (condenser microphone) are disposed in a cavity of a soundproof housing (21). The units A (22) are provided in a feedback loop and an output level of the unit B (23) is adjusted by an preamplifier (24). An output of the preamplifier is sampled by a sample-and-hold circuit (25) and an output thereof is delta-modulated by a delta modulation circuit (26). The number of pulses produced by the circuit (26) is subjected to arithmetic operation in an arithmetic circuit (27) to produce a drive signal for the units A. Vibration of a vibration film of the unit B (23) is detected and arithmetical control is made to be always maintained to zero. On the other hand, an audio signal supplied from a signal terminal (28) is superposed on a drive signal for the units A and is emitted into the cavity.






Search report