(19)
(11)EP 1 220 220 A3

(12)EUROPEAN PATENT APPLICATION

(88)Date of publication A3:
31.08.2005 Bulletin 2005/35

(43)Date of publication A2:
03.07.2002 Bulletin 2002/27

(21)Application number: 01310629.9

(22)Date of filing:  19.12.2001
(51)Int. Cl.7G11B 20/24, G05F 1/10, H04B 1/10, H04B 3/56, G11B 5/027
(84)Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR
Designated Extension States:
AL LT LV MK RO SI

(30)Priority: 28.12.2000 JP 2000402231
15.01.2001 JP 2001006609

(71)Applicant: SONY CORPORATION
Tokyo 141 (JP)

(72)Inventors:
  • Yata, Toru, c/o Sony Corporation
    Tokyo 141 (JP)
  • Hanagata, Tsutomu, c/o Sony Corporation
    Tokyo 141 (JP)
  • Itayama, Osamu, c/o Sony Corporation
    Tokyo 141 (JP)
  • Miyamoto, Takuya, c/o Sony Corporation
    Tokyo 141 (JP)
  • Arihara, Akihiro, c/o Sony Corporation
    Tokyo 141 (JP)
  • Takehara, Shintaro, c/o Sony Corporation
    Tokyo 141 (JP)
  • Takano, Naoto, c/o Sony Corporation
    Tokyo 141 (JP)

(74)Representative: Pratt, Richard Wilson et al
D Young & Co 120 Holborn
London EC1N 2DY
London EC1N 2DY (GB)

  


(54)Filtering and interference removal


(57) An audio signal playback circuit includes an operational amplifier having an equalizer amplifier for amplifying a signal from a head, and filters, particularly a T-filter formed of coils and a capacitor, for detecting and attenuating the 900 MHz frequency band. The filters are provided at or before ports of a signal line and a power supply line which are electrically connected to the operational amplifier. A servo-control CTL signal playback circuit includes an amplifier circuit for amplifying a signal generated by playing back a CTL signal using a control head, the CTL signal being recorded in a recording medium, a servo control unit for controlling a servo in response to the signal amplified by the amplifier circuit, and a filter for detecting and attenuating the 900 MHz frequency band. The filter is provided at or before a port of a signal line for inputting the signal played back by the control head to the amplifier circuit. The filter in the audio signal playback circuit or the servo-control CTL signal playback circuit allows an interference signal having a low-frequency component in the 900 MHz band to be removed before it is amplified.