(19)
(11) EP 0 273 447 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
07.03.1990 Bulletin 1990/10

(43) Date of publication A2:
06.07.1988 Bulletin 1988/27

(21) Application number: 87119324.9

(22) Date of filing: 29.12.1987
(51) International Patent Classification (IPC)4: G10H 7/00, G10H 1/12
(84) Designated Contracting States:
DE GB

(30) Priority: 30.12.1986 JP 311285/86

(71) Applicant: YAMAHA CORPORATION
Hamamatsu-shi Shizuoka-ken (JP)

(72) Inventor:
  • Suzuki, Hideo
    Hamamatsu-shi Shizuoka-ken (JP)

(74) Representative: Selting, Günther, Dipl.-Ing. et al
Patentanwälte von Kreisler, Selting, Werner Postfach 10 22 41
50462 Köln
50462 Köln (DE)


(56) References cited: : 
   
       


    (54) Tone signal generation device employing a digital filter


    (57) An address signal generation circuit generates an address signal which changes at a rate corresponding to tone pitch of a tone to be generated. This address signal consists of an integer section (IAD) and a decimal section (FAD). A tone waveshape data generation circuit (13) generates tone waveshape sampled data in response to the integer section (IAD) of the address signal. A filter coefficient supply circuit (24) can generate data corresponding to filter coefficients of m orders and selects and supplies n filter coefficients (where n < m) in response to the decimal section (FAD) of the address signal. In a relation n = m/d, for example, the filter coefficient supply circuit (24) selects filter coefficients corresponding to n orders which are distant sequentially with an interval of d in response to the value of the decimal section of current address signal. A digital filter operation circuit (21) performs filter operations of m orders with respect to tone waveshape data of n sample points by using these n filter coefficient data and tone waveshape data of n sample points generated by the tone waveshape data generation circuit (13). By this arrangement, despite that the actual filter operation is carried out only with respect to data corresponding to the n orders, a filter operation equivalent to performing filter operations of m orders can be realized.







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