Tetsuo Nishimoto

Electronic musical instrument using amplitude modulation with feedback loop

In a musical tone synthesizer in which an amplitude-modulated carrier wave delivered from an amplitude modulator is used to form a musical tone signal, the amplitude-modulated carrier wave is fed back to the input side of the amplitude modulator as a modulation signal, a portion thereof, a portion of a carrier wave or a composite signal of the modulation signal and the carrier wave. The amount of feedback may be controlled by multiplying the amplitude-modulated carrier wave with a predetermined modulation index. Furthermore, the modulation index may be charged with time so that the control of spectrum construction of the musical tone signal is readily performed. According to a modified embodiment, a plurality of amplitude-modulators are provided which are connected in a ring form feedback loop in which the modulated outputs of preceding amplitude modulators are supplied respectively to succeeding amplitude modulators.

Digital touch response circuit of electronic musical instrument

In a digital touch response circuit or touch signal processing circuit for producing a control waveform signal to control a musical tone to be produced in response to a players finger touch on a key, digital touch data representing a players instantaneous finger touch on a key is compared in a comparison circuit with digital output data from an operation circuit such as an adder circuit, which varies at a rate as the result of addition of a rate value to input data applied to the adder. A selection circuit is responsive to the comparison circuit to selectively couple the output data of the adder and the digital touch data to a temporary memory circuit such as shift registers. The output data from the memory circuit is coupled to the adder as the input data thereto. When the pressure applied to the key is increasing (crescendo) the digital touch data is fed to the memory through the selection circuit, and, when the pressure applied to the key is decreasing (diminuendo) at a rate larger than the rate at which the output data of adder varies, the output data of the adder is coupled to the memory circuit via the selection circuit to thereby obtain a decaying control waveform signal. The output data of the memory is utilized to form the control envelope.

Electronic musical instrument capable of producing a musical tone by varying tone color with time

Each one of a plurality of harmonic components is multiplied with a first amplitude coefficient to form a plurality of harmonic components corresponding to a musical tone signal having a desired waveform. Each of the harmonic components is varied with time by a first envelope waveform signal in accordance with a second amplitude coefficient corresponding to each harmonic to form a harmonic component of a spectrum varying with time in a desired manner. By using a second envelope waveform signal, amplitudes of respective harmonic components are varied in a predetermined manner and then the harmonic components are synthesized to form a musical tone.

Parameter setting system for electronic musical instrument

A parameter setting system for an electronic musical instrument has a predetermined number of panel switches to which desired parameters can be selectively assigned by the player. The system comprises a RAM having a parameter area in which a group of parameters determining characteristics of a tone are stored, the number of parameters being greater than the number of the panel switches. The RAM also has an identification-number area for storing identification numbers of those parameters which are assigned respectively to the panel switches. When a reassignment switch is depressed with an entry switch, the system is brought into a reassignment mode. In this condition, the player selects a desired one of the parameters using up and down switches for changing the identification number and a display unit for displaying the identification number. The player then depresses one of the panel switches to which the selected parameter is to be assigned, whereupon the displayed identification number is stored into the identification-number area of the RAM at a position corresponding to the depressed panel switch.

Control waveform generating apparatus for an electronic musical instrument

A control waveform generating apparatus for an electronic musical instrument generates a control waveform having at least a rising portion and a falling portion whose levels vary in a lapse of time. The control waveform is divided into a plurality of segment waveforms each of which includes a constant level portion (an interval portion) and at least one of the rising portion and the falling portion therein. The rising rates and falling rates and interval durations of the respective segment waveforms are selected by a player so that the control waveform having an arbitrary waveform can be obtained. When generating the control waveform, each of the plural segment waveforms is sequentially designated and outputted as a part of the entire control waveform. When the present segment waveform next to the preceding segment waveform is designated, the last level of the preceding segment waveform is maintained in a selected interval period. After this predetermined interval period is passed, the level of the present segment waveform increases or decreases according to a selected rising rate or falling rate.

Keying system for an electronic musical instrument

A keying system for an electronic musical instrument in which the absolute value of the amplitude of a musical tone signal generated with a predetermined periodicity is detected so that gating of the musical tone signal is allowed only when the amplitude of the musical tone signal is small, thereby to prevent the occurrence of click noises accompanying the keying of the musical tone signal in correspondence to depression and release of a key in a keyboard.