Electronic musical instrument

• US 4,306,480 A
• Filed: 03/29/1977
• Issued: 12/22/1981
• Est. Priority Date: 03/29/1977
• Status: Expired due to Term

• Current Assignee: Frank Eventoff, Serge A. Tcherepnin
• Original Assignee: Frank Eventoff, Serge A. Tcherepnin
• Inventors: Tcherepnin, Serge A., Eventoff, Frank
• Primary Examiner(s): Truhe, J. V.
• Assistant Examiner(s): Isen, Forester W.
• Application Number:
  US05/782,431
• Time in Patent Office: 1,729 Days
• Field of Search: 84/1.01, 84/1.14, 84/1.15, 84/1.16, 84/1.24, 84/1.25, 84/DIG. 7, 84/DIG. 9, 84/1.19, 84/DIG. 10, 84/DIG. 24
• US Class Current: 84/672
• CPC Class Codes: G10H 1/02 Means for controlling the tone frequencies, e.g. attack or decay; Means for producing special musical effects, e.g. vibratos or glissandos
• CPC Class Codes: G10H 1/34 Switch arrangements, e.g. keyboards or mechanical switches specially adapted for electrophonic musical instruments
• CPC Class Codes: G10H 2210/211 Pitch vibrato, i.e. repetitive and smooth variation in pitch, e.g. as obtainable with a whammy bar or tremolo arm on a guitar non-repetitive smooth pitch variation, e.g. glissando G10H2220/221; repeatedly alternating stepwise in pitch between two notes G10H2210/191
• CPC Class Codes: Y10S 84/09 Filtering
• CPC Class Codes: Y10S 84/24 Piezoelectrical transducers

Abstract

An electronic musical instrument having a fret board and a plurality of conductive frets may be coupled to a resistance ladder of discrete resistive elements. A conductive wire or a plurality of such wires selectively making contact with at least one of the conductive frets forms, together with the resistance ladder, part of a tone generating circuit. The circuit includes an oscillator which generates a tone in response to the conductive fret with which the wire makes contact. The circuit may also include a wave shaping circuit which selectively alters the shape of the generated tone and through a series of gradations alters its operating characteristics from that of a full wave rectifier to a linear voltage follower. Another embodiment modulates the phase of the generated tone by exploiting the dynamic impedance of a diode. One or more unique pressure sensitive touch pads may be employed for a glissando effect and/or for volume and/or tone glides. The instrument includes a single chromatic semitone switch and may be tuned to any key by a variable control. The circuit may also include variable vibrato, timbrato and tremolo effects. Inclusion of an octave switch and variable tuning between frets is also possible.

Claims

1. An electronic musical apparatus comprising:

a sound box;

a fret board coupled to said sound box;

a plurality of discrete conductive frets disposed on said fret board;

a plurality of discrete resistive elements coupled to said plurality of discrete conductive frets;

first means coupled to said plurality of resistive elements for generating a first signal having a selected one of a plurality of fundamental frequencies within a range of fundamental frequencies, first signal having a waveshape definable by the sum of a plurality of sine waves having a frequency spectrum;

second means having its input coupled to the output of said first means for selectively modifying the frequency spectrum of sine waves defining the waveshape of the first signal for modifying the waveshape of the first signal without substantially altering the amplitude of the first signal regardless of the fundamental frequency of said first signal within the range of fundamental frequencies;

means for biasing the input of the second means in a range between a first bias extreme and a second bias extreme, said second means selectively obtaining the output characteristics of a full wave rectifier at the first extreme, obtaining the output characteristics of a voltage follower at the second extreme, and obtaining gradations between said first and second extremes;

a source of electrical power; and

conductive means disposed on said fret board and adapted to selectively couple said source of electrical power to at least one of said plurality of discrete conductive frets, whereby musical tones may be audibly generated according to a fixed musical scale in a manner functionally equivalent to conventional stringed instruments.

2. An electronic musical apparatus comprising:

a sound box;

a fret board coupled to said sound box;

a plurality of discrete conductive frets disposed on said fret board;

a plurality of discrete resistive elements coupled to said plurality of discrete conductive frets;

first means for generating a plurality of tones coupled to said plurality of resistive elements, said first means generating a periodic current;

a constant amplitude phase shifter having a first node, the periodic current from the first means being coupled to the first node, the phase shifter comprising;

a current differential amplifier,

second means coupled between ground and the node for providing a low-resistance path to said periodic current when said periodic current has a first polarity and a high resistance path when said periodic current has a second polarity opposite to said first polarity,

third means for providing a selective resistance path coupling the input of said amplifier to said node, and

fourth means coupled between the node and the input of the current differencing amplifier for reflecting the periodic current passing through the second means to the input of the amplifier as a periodic signal which is out-of-phase with the periodic current passing through the second means,

fifth means for biasing said node to shift said periodic current by a bias current;

second means having its input coupled to the output of said first means for selectively modifying the frequency spectrum of said plurality of tones generated by said first means and for modifying the waveshape, without substantial alteration of amplitude regardless of the frequency of said plurality of tones, said second means selectively obtaining the output characteristics of a full wave rectifier at a first extreme, obtaining the output characteristics of a voltage follower at a second extreme, and obtaining gradiations between said first and second extremes;

a source of electrical power; and

conductive means disposed on said fret board and adapted to selectively couple said source of electrical power to at least one of said plurality of discrete conductive frets, whereby musical tones may be audibly generated according to a fixed musical scale in a manner functionally equivalent to conventional stringed instruments.

3. The apparatus of claim 2 wherein said third means is a diode.

4. The apparatus of claim 2 wherein said third means is a capactive element.

5. The apparatus of claim 2 wherein a plurality of said constant amplitude phase shifters and at least one fifth means are employed in an ordered series of cascaded unit circuits, the output of each said constant amplitude phase shifters being coupled to the input of the next higher ordered constant amplitude phase shifter.

6. The apparatus of claim 2 wherein said bias current is audio frequency modulated.

7. In a musical instrument, a circuit comprising:

a plurality of discrete resistive elements, each having a contact node coupled thereto;

conductive wire means for selectively coupling with at least one of said contact nodes;

an oscillator coupled to said plurality of discrete resistive elements and said conductive wire means to selectively generate a plurality of periodic electric signals each having a distinct principal frequency and a distinct waveshape definable by a combination of a plurality of sine waves having a frequency spectrum;

tone enhancement means for selectively altering the frequency spectrum of the plurality of sine waves defining the waveshape for modifying the waveshape without substantially altering the amplitude of the periodic electrical signals regardless of the principal frequency, said tone enhancement means having an input coupled to the output of said oscillator and including;

an amplifier having an input,

an input diode having a frequency dependent impedance and coupled between ground and the input of the tone enhancement means,

and a capacitor coupled between the inputs of the tone enhancement means and the amplifier wherein said periodic electrical signals tend to be frequency split across the impedance of said capacitor and the frequency dependent impedance of said diode means, for inverting and coupling said periodic electrical signals across said diode to said amplifier input; and

audio means for generating an audible signal in response to said altered periodic signal coupled to said tone enhancement means.

8. In a musical instrument, a circuit comprising:

a plurality of discrete resistive elements, each having a contact node coupled thereto;

conductive wire means for selectively coupling with at least one of said contact nodes;

an oscillator coupled to said plurality of discrete resistive elements and said conductive wire means to selectively generate a plurality of periodic electrical signals each having a distinct principal frequency; and

a distinct waveshape definable by a combination of a plurality of sine waves having a frequency spectrum;

tone enhancement means for selectively altering the frequency spectrum of the plurality of sine waves defining the waveshape for modifying the waveshape of the periodic electrical signals without substantially altering the amplitude of the periodic electrical signals regardless of the principal frequency, said tone enhancement means having an input coupled to the output of said oscillator and including;

an amplifier having an input,

a first input diode coupled between ground and the input of the tone enhancement means and having a first preferred direction of conductivity, and

a second input diode coupled between the input of the amplifier and the tone enhancement means input, said second input diode having a second preferred direction of conductivity opposite to said first direction, a source of variable bias voltage coupled to the input of the tone enhancement means, and

means coupled between the first diode and the amplifier input for inverting and coupling the voltage across said first diode to said amplifier; and

audio means for generating an audible signal in response to said altered periodic signal coupled to said tone enhancement means.

9. In a musical instrument, a circuit comprising:

a plurality of discrete resistive elements, each having a contact node coupled thereto;

conductive wire means for selectively coupling with at least one of asid contact nodes;

an oscillator coupled to said plurality of discrete resistive elements and said conductive wire means to selectively generate a plurality of periodic electrical signals each having a distinct principal frequency; and

a distinct waveshape definable by the combination of a plurality of sine waves having a frequency spectrum;

tone enhancement means for selectively altering the frequency spectrum of the plurality of the sine waves defining the waveshape of the periodic electrical signals for modifying the waveshape without substantially altering the amplitude of the periodic electrical signal regardless of the principal frequency, said tone enhancement means having an input coupled to the output of said oscillator; and

audio means for generating an audible signal in response to said altered periodic signal coupled to said tone enhancement means;

said enhancement means including;

a voltage controlled waveshaping circuit coupled to said oscillator;

a voltage controlled phase shifting circuit coupled to said waveshaping circuit; and

a voltage controlled amplifier coupled to said phase shifting circuit; and

a variable modulating oscillator having an input selectively coupled to said waveshaping circuit for timbrato, to said phase shifting circuit for phasing, to said voltage controlled amplifier for tremolo and to said oscillator for vibrato modulation.

10. The circuit of claim 9 wherein said waveshaping and voltage controlled amplifier and said oscillator may includes a pressure sensitive means for producing random glides of tone, volume and pitch respectively.

11. The circuit of claim 10 wherein said variable modulation oscillator generates a sub-audio output.