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Tone generation system for electronic musical instrument

  • US 4,333,377 A
  • Filed: 03/03/1981
  • Issued: 06/08/1982
  • Est. Priority Date: 08/17/1979
  • Status: Expired due to Fees
First Claim
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1. In an electronic musical instrument of the type wherein an audible tone is generated electronically in response to an actuation of tone initiating means of the instrument by a player, an envelope generation system for producing a plurality of envelope signals which define a preselected envelope waveform, said envelope generation system comprising:

  • input circuit means responsive to player actuation of said tone-initiating means for producing envelope control signals and for producing a series of envelope count signals, clock means for generating a series of timing signals, envelope control circuit means responsive to said envelope control signals and to said timing signals for generating a series of predetermined digital increment defining signals, arithmetic circuit means for performing predetermined arithmetic functions utilizing said increment defining signals and said envelope count signals to produce therefrom a series of digital envelope signals collectively defining said envelope waveform wherein said arithmetic circuit includes means for producing said series of digital envelope signals Yx in accordance with the equation Yx =Yx -1±

    Δ

    Y where x represents one of said series of envelope count signals, Yx and Yx -1 represent ones of said digital envelope signals produced in response to envelope count signals x and x-1, and Δ

    Y represents one of said digital increment defining signals, said envelope generation system further including scaling means for producing a digital scaling signal corresponding to the intensity of player actuation of said tone initiating means and wherein said arithmetic circuit means further includes means for producing said series of digital envelope signals Yx in accordance with the equation Yx =Yx -1±



    Δ

    Yx, where S represents said digital scaling signal.

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