Electronic musical instrument

• US 4,348,928 A
• Filed: 09/19/1977
• Issued: 09/14/1982
• Est. Priority Date: 09/24/1976
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaishi Kawai Gakki Seisakusho
• Original Assignee: Kabushiki Kaishi Kawai Gakki Seisakusho
• Inventors: Kitagawa, Hiroshi, Watanabe, Hironori, Sakashita, Noriji, Kugisawa, Toshio
• Primary Examiner(s): Truhe, J. V.
• Assistant Examiner(s): Isen, Forester W.
• Application Number:
  US05/834,427
• Time in Patent Office: 1,821 Days
• Field of Search: 84/1.01, 84/1.03, 84/1.11, 84/1.19, 84/1.24, 84/1.26, 84/DIG. 7, 84/DIG. 8, 364/718, 364/723
• US Class Current: 84/604
• CPC Class Codes: G10H 1/0575 using a data store from which the envelope is synthesized tones synthesized from a data store G10H7/00
• CPC Class Codes: G10H 1/18 Selecting circuits
• CPC Class Codes: G10H 7/045 using an auxiliary register or set of registers, e.g. a shift-register, in which the amplitudes are transferred before being read

Abstract

An electronic musical instrument of digital processing in which required musical waveshape data are calculated by a tone control device to obtain a complex musical waveshape and the complex musical waveshape is read out at a read frequency produced by a key closure to generate the selected musical note. The electronic musical instrument has a calculator for calculating a musical waveshape in association with the operation of the tone control device in a period of time independent of the period of the generated musical note, a read-out signal generator for producing a memory read-out signal based on the closure of the key switch, a period detector for detecting by one period of each channel resulting from the closure of the key switch, first and second memories for storing the musical waveshape from the calculator, the stored musical waveshape being read out by the read-out signal, and means for achieving such a control that while the first memory is read out, the musical waveshape is stored in the second memory, that the read output signal from the first memory is sequentially written in the second memory by the output signal from the period detector in synchronism with the period of the generated musical note and that after completion of reading out of a new first memory, the musical waveshape from the calculator is stored in the first memory.

Claims

1. An electronic musical instrument for digital processing having a tone control in which required musical waveshape data are computed to obtain a complex waveshape, a keyboard having key switches on which a musical note having a frequency and a period is selected by closure of a key switch, and in which the complex waveshape is read out by a read-out frequency of the selected note to produce the selected musical note, the electronic musical instrument comprising:

a calculator coupled to the tone control for calculating the musical waveshape in association with the operation of the tone control in a period of time independent of the period of the selected musical tone;

a read out signal generator for generating a memory read-out signal based on the closure of the key switch;

a period detector for detecting the read-out signal period resulting from the closure of the key switch;

first and second memories storing the musical waveshape from the calculator and read out by the read-out signal; and

means for controlling the first and second memories to be written into and read out alternately with each other so that while the first memory is read out by the read-out signal, the musical waveshape from the calculator is written into the second memory, the read out operation is then switched to the second memory by a signal from the period detector in synchronism with the period of the musical note, and after completion of the read out of the first memory, the waveshape from the calculator is written into the first memory while the second memory is read out by the read-out signal, and further comprising;

a memory having stored therein quantized amplitude values of an envelope waveshape, the different values between successive amplitude values of the envelope waveshape, and sign bits representing the positive or negative of the difference values, and for providing high-order and low-order count values of the envelope waveshape, an envelope waveshape generator provided with a high-order and a low-order envelope counter for executing at all times and read-out of said memory;

a coincidence circuit for detecting the coincidence between the count value of the high-order envelope counter and an address signal of the memory;

a gate circuit opened by a coincidence signal from the coincidence circuit;

a first multiplier having two inputs, the amplitude values stored in the memory being applied to one input of the first multiplier and a multiplier value dependent on the number of bits of the low-order envelope counter being applied to the other input of the first multiplier;

a second multiplier having two inputs, the difference values stored in the memory being applied to one input of the second multiplier and the count value of the low-order envelope counter being applied as a multiplier value to the other input of the second multiplier;

an adder-subtractor clock, the outputs from the first and second multipliers being applied to the adder-subtractor clock;

a plurality of channels corresponding to the maximum number of sounds to be simultaneously produced, each channel having a key-code detector;

a main oscillator providing a signal to said adder-subtractor clock, said adder subtractor clock producing pulses to the key code detectors of the respective channels based on the signal from the main oscillator;

time division clocks for time dividing note signals identifying the note of the closed key switch;

a note clock generator circuit having a decoder for distributing the time divided note signals from the time division clocks;

note clock generator pulsed by said decoder for variably frequency-dividing the signal from the main oscillator based on the stored data of the first and second memories to thereby generate frequencies within desired sound ranges in a sample period of the musical waveshape written in the first and second memories and read out therefrom, and gate circuit means for gating output signals from the note clock generators for addition or subtraction depending upon the sign bits being positive or negative.

2. An electronic musical instrument as in claim 1, and further comprising a note clock generating device provided with key code detectors for detecting depression and release of a key switch and for generating the note signal identifying the note of the closed key switch and an octave signal identifying the octave thereof for each of the channels;

a sequential pulse generator for applying time division to the channels by means of the time division clock, and an octave frequency selector for selecting octave frequencies of the output signals from the gate circuits of the note clock generator circuit by the time divided octave signals of the respective channels for the key code detectors.

3. An electronic musical instrument as in claim 1, wherein said tone control produces a set value and a feet rate, and further comprising divider means for dividing the musical waveshape data into a desired number of periods, each of which is represented by a period number having a desired function and a coefficient value;

a memory for storing each period number and the coefficient value;

a multiplier for multiplying the coefficient value from the memory by the set value from the tone control;

an accumulator for accumulating the multiplied coefficient value from the multiplier based on the period number from the memory;

means for developing a shift pulse corresponding to the feet rate from the tone control; and

means for sequentially writing the output signal from the accumulator in a shift register through an adder by means of said shift pulse.