CA1237302A - Electronic musical instrument - Google Patents

Electronic musical instrument

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Publication number
CA1237302A
CA1237302A CA000519926A CA519926A CA1237302A CA 1237302 A CA1237302 A CA 1237302A CA 000519926 A CA000519926 A CA 000519926A CA 519926 A CA519926 A CA 519926A CA 1237302 A CA1237302 A CA 1237302A
Authority
CA
Canada
Prior art keywords
instrument
string
control
strings
voltage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000519926A
Other languages
French (fr)
Inventor
Frank Meno
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to CA000519926A priority Critical patent/CA1237302A/en
Application granted granted Critical
Publication of CA1237302A publication Critical patent/CA1237302A/en
Expired legal-status Critical Current

Links

Abstract

Abstract An electronic stringed instrument which uses electrical resistance wires as strings to control the frequency of electrically generated sounds. By shorting a string at various points along its length a variable voltage output is obtained and converted into a known frequency. A fretted instrument provides a means to incrementally control the voltage output and a non-fretted type instrument with a conducting fingerboard can provide a means to variably control the voltage output. A separate current source may be provided for each string to faciliate chord playing and a control for the intensity and harmonic content of the signals is provided. An internal power supply and speaker may also be employed to make the instrument readily portable.

Description

~7~

This application is a division of my Canadian patent application Serial No. 44Q,085 filed October 31, 1983.
~ his invention relates to electronic, stringed musical instruments and more specifically, it relates to the use of resistance wires as strings which control the Erequency of electronically generated sounds in such instruments~
It has been known to vary the resistance in a Wienbridge oscillator in an electrical circuit associated with a musical instrument. See United States Patent No. 3,624,584.
United States Patent No. 3,626,350 discloses a means to produce a portamento chord by utilizing this principle.
United States Patent No. 3,948,137 discloses prior art which allows the player of an instrument utilizing a voltage controlled oscillator to control sound effects by providing wave form, filter and gain controls.
United States Patent No. 4,235,141 discloses an instrument wherein an apertured insulating strip is inserted between an electrically conaucting strip and a resistive strip to only allow contact points at predetermined locations, there-~0 by producing a tone at discrete selected values of frequency.
Electrically synthesized music is an increasinglypopular art form in which substantial technological advances have been made. In the past, however, most of these advances could only be utilized in a keyboard type instrument excluding musicians skilled primarily in the playing of stringed instru-ments.
A known attempt to provide a voltage controlled electronic stringed instrument is United States Patent No. 4,038,897.

~;~373~2 In this patent, a guitar or other fretted instrument is used to produce input signals for a voltage-controlled tone generator or the guitar can be used in the coventional fashion by operating a switch. Each string-fret pair has an assigned musical tone. Voltages analogous to said tones are applied to the instruments frets so as to apply such voltage to the strings when the strings contact the frets.
Such systems have several major limitations.
Firstly, the invention is limited to fretted stringed instruments. Additionally, complicated wiring of resistors to each fret is required in order to provide each with the proper voltage value. Finally, providing the voltage to electrically conducting frets appears to foreclose the possibility of playing chords without fret segmentation.
There remains, therefore, a need for a stringed electronic instrument which provides effective frequency control in either fretted or unfretted string instruments employing the strings as resistance and a means for playing chords whether or not frets are desired.

SUMMARY OF THE INVENTION
The present invention has produced a solution to the above need by providing an instrument which uses electrical resistance wires as strings to control the frequency of electrically generated sounds. The frequencies are produced by voltage to frequency converters or other suitable circuits.
More specifically, the variable voltage output that controls frequency is obtained by shorting at various points along its length a constant electrical current supplied to a string.
This shorting operation can be employed in two distinct classes :3_23i~3~

of stringed instruments. In a guitar or other fretted instru-ments the resistance strings can be shorted at any single fret providing a means to incrementally control the voltage output of the instrument~ In a violin or other non-fretted instru-ments the surface of the fingerboard facing the strings can be made of an electrical conducting material so the resistance strings can be shorted at any point providing a means to variably control voltage output.
Each string is provided with a separate current source but all strings are referenced to the same grounding point. The frets or the entire conducting surface of the neck in the case of a violin type instrument are also grounded. The non-grounded end of each string is connected to a current source. The voltage drop is detected so that the strings do not interfere with each other at the frets and consequently, chords can be played.
In the past, most voltage controlled electronic instruments employed Wien-bridge oscillators or similar circuits which required relatively high resistance values for the control element. The present invention, however, utilizes a voltage to frequency converter circuit which can be control-led by relatively low resistance values as the voltage can be amplified before conversion, making possible the use of low resistance wires as the control elements. Furthermore, the high stability of the resistance, the constant current sources, and the precision of commercial voltage to frequency converters will make this type of instrument of professional quality.
The embodiments of the present invention provide a means for controlling the intensity and harmonic content of the signals produced. More specifically, suitable attenuators and ~lZ37~30~

filters are controlled by ~ne of the player'~ han~s while the other presses the strings to produce the desired frequency.
Wound resistance wire strings may be provided for low notes as well as a method for producing the same.
In one embodiment of the present invention an internal power supply and speakér are provided to make the instrument readily portable.
In another embodiment of the present invention a frequency co~nter is integrated into the instrument's electrical circuit to facilitate tuning.
It is further contemplated that combining the electrical and mechanical strin~ produced sounds may have potential for expanding the instruments artistic possibilities.
It is an object of the present invention to provide a voltage controlled stringed musical instrument which utilizes resistance wires as strings.
It is yet another object to employ resistance wire strings in both fretted and non-fretted instruments.
It is a further object of the present invention to utilize a constant current generator in embodiments in which a linear relationship between the length of the string and the frequency is desired.
It is yet another object of this invention to provide a means to produce suitable strings for the instrument.
It is yet another object of this invention to provide a means for controlling the intensity and harmonic content of the sounds produced, It is yet another object of this invention to provide a self-contained package including a speaker and internal power source so as to make said instrument readily portable.

30;;;~

In accordance with a broad aspect of the invention of this divisional application there is provided a method for producing a wound string for a voltage controlled stringed instrument which utilizes resistance wires as strings to control the frequency of electronically generated sounds comprising the steps of: tightly winding well insula-ted resis-tance wire about a core, dipping said wound string into a suitable resin, and removing said insulation and resin from the outer surface of said wound string.

-4a-These and other objects of the invention will be fully understood from the following description of the invention on reference to the illustrations appended hereto.

BRIEF DESCRIPTION OF ri~E DRAWINGS
Figure 1 is a schematic view of one form of the invention showing an electrically insulating fingerboard and conducting frets.
Figure ~ is a cross-sectional view of the fingerboard shown in Figure 1 taken through 2-2 of Figure 1.
Figure 3 is a schematic circuit diagram of a circuit to provide a suitable constant current source for the instru-ment.
Figure 4 is a cross-sectional view of a wound resistance wire string.
Figure 5 is a block diagram of the various steps involved in converting changes in the string resistance into frequency signals of desired quality characteristics.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
As used herein, in the absence of a clear, express indication to the contrary at a specific location, the tèrms "string" and "strings" refer to either straight or wound electrically conductive resistance wires~
As used herein, in the absence of a clear, express indication to the contrary at a particular location the terms "conducting" and "insulating" refer respectively to a materials capacity to conduct or to resist the conduction of an electri-cal current.
The present invention provides a musical instrument ~%3'7~

which varies the input voltage in an electr;cal circuit and converts the voltage to a frequency to produce a responsive musical tone. The voltage (V) in the circuit is dependant upon two variables, current (I) and resistance (R) according to V=IR. It is preferred, but not required, to provide the instrument with a constant current source of power which results in a linear relationship between the voltage and resistance. The instrument's strings provide the resistance element in the circuit. By urging a string against a con-ducting surface at differenct points along the string's lengththe circuit's resistance and the resulting voltage drop can be effectively controlled and varied.
Referring more specifically to Figures 1 and 2 (wherein for clarity of illustration the strings have not been shown), one embodiment of the present invention, a guitar type fretted instrument is shownO The instrument 3 has a body 6 having any convenient shape and preferably is made of a rigid electrically insulating material. One end of neck 9 is secured to the body as by conventional means. The neck 9 is also preferably an insulator but both the neck and body may be conductors if desired. A rigid insulating fingerboard 12 is attached to neck 9u A hardwood or rigid plastic would be a suitable material to construct the fingerboard 12. An insulating bridge 15 is also secured to the body 6, so as to provide a means to elevate the strings a slight distance above the fingerboard 12.
A plurality of conducting frets 16 are embedded across the fingerboard 12 at desired points along its length.
The fret spacing may remain essentially the same as in regular guitars, and the current can be adjusted to correspond to the same notes. The frets 16 are preferably made from a hard conducting metal such as stainless steel. Embedded at the end of the fingerboard 12 farthest away from the body 6 is a rigid conducting shorting bar 18 to support the strings (not shown) a slight distance above the uppermost fret 16.
Each of the frets 16 are electrically connected together in series and connected to the electrically grounded shorting bar 18 by a conductive connecting wire 30, as shown in Figures 1 and 2. The frets 16 may be connected together and to the shorting bar by any other suitable means such as a conducting strip mounted under the insulating fingerboard 12 which contacts each of said frets 16.
The strings (not shown) are attached to the instrument by conventional means and, as mentioned, are supported above the frets on one end by the insulating bridge 15 and at the other end by the shorting bar 18. The strings are tuned mechanically by adjusting their tension by turning tuning keys 26 in the usual fashion. Electronic tuning of each string is accomplished by turning a potentiometer knob 27 suitably wired into the circuit by means well known in the art. A frequency counter 33 may also be integrated into the circuit to facilitate tuning. A constant current power source and amplifier circuit 28 ~see Figure 3) is connected to each string at or near the bridge lS by any suitable means. It is preferable to make these connections at points 29 to avoid interference with the strings mechanical vibration. Points 29 may also serve as the input to an amplifier. It is contem-plated that an internal power supply 42 and speaker 45 could also be provided to make the instrument more portable. It is preferable to keep the resistance values of the strings below r~ s ~ s J~ ~
,~ 1000 ohms so that the changes in finger contact }~i~ta~ do not play a perceptive role, unless such an effect were desired. Contacting a string to a chosen fret will complete an electrical circuit and create a desired voltage output which is then converted into a frequency signal by means well known in the art. Such voltage to frequency converters are now avail-able as commercial intergrated circuits.
It will be appreciated by those skilled the art that by eliminating the frets and replacing or covering the insul-ating fingerboard with a sheetlike conducting fingerboard, aviolin type non-fretted instrument will function essentially as described above. With this embodiment continuous variability of pitch can be achieved.
The present invention also provides a means for controlling the harmonic content and intensity of the signals produced. First, the pitch or fundamental frequency is select-ed by means of a particular string. Harmonic frequencies are then selected by color control registers 39.
It is contemplated that the loudness can be effec-tively controlled in one of two ways. In one embodiment,thestrings would be plucked or ban9ed as in conventional instru-ments Below each string would be placed an electromagnetic pickup 31 as is done in conventional electric guitars. The output of this pickup would then be amplified and rectified to derive the intensity envelope of the vibration, which is proportional to loudness. This loudness envelope voltage would then be used to control the loudness of the electronic sound by means of voltage controlled amplifiers.
In another embodiment of the present invention, it is contemplated that suitable pressure transducers 32, which can 3~2 respond properly and rapidly to ~inger pressure, could be manipulated by the players free hand to control loudness. The above mentioned pressure transducers could be in the form of buttons, perhaps one to control each string or any combination of strings. The voltage from these transducers would be applied through a voltage controlled amplifier to effectively control loudness. The separate control of the duration and loudness of each note in a chord is made possible by the use of this method, thereby, allowing for greater flexbility and creative potential.
Figure 3 shows a schematic circuit diagram of a typical circuit to provide a sui~able constant current source for this instrument and the first stage of amplification. The constant reference voltage -Vz is obtained by means of the Zener diode 80 and the resistor 81. The resistor network R3, R2 and RT apply a fraction of this voltage to the non-inverting input of the operational amplifier 82. The inverting input is connected to the resistor Rl in which the voltage drop is proportional to the current IS which flows through the control-ling field-effect transistor 83 and the string 84 with the effective resistance Rs. The voltage drop over RS is ISRs.
This is fed to the amplifier 85 with the provision to adjust the gain by means of the control 86. The value of the constant current IS can be adjusted by means of the tuning control 87 through the relationship IS = V~R3/Rl (R2+R3+RT).
Figure 4 represents a cross-sectional view of a string wound with resistance wires for low notes. A steel wire 75 of suitable diameter is used for the core. A well insulated resistance wire 77 is then tightly wound onto wire 75. The whole string 79 might then be dipped into a suitable resin ~;~373~

(such as epoxy) to tightly fixate the insulation 78 in order to prevent electrical contact towards the core and between the turns on account of abrasion due to internal flexing. The insulation 78 would then be removed as by sanding only on the string's outer surface so that the string can make contact with the frets.
Figure 5 is a block diagram of one embodiment of the present invention showing the various steps in converting voltage signals into frequency signals of desired wave char-acteristics. As string 39 is pressed to contact fret 40 an electrical circuit is completed. The resistance of the portion of the string now included in the circuit will alter the voltage in the circuit according to V=IR. By pressing the string to contact other frets (not shown) different voltage ouputs can be obtained. The voltage signal is then amplified by the operational amplifier curcuit ~5 as shown. As indicated in block 50 of Figure 5, the amplified voltage signal obtained by the above described method is then converted into a frequency signal. Depending on the type of voltage to frequency converter employed the output frequency signal may be a sine wave or some other wave form. This output frequency signal may then by inputted into a wave shape former shown in block 55. After a desired wave form is obtained, the basic frequency signal may then be filtered to remove undesired "harmonics~ in the circuit as is indicated by block 60. Block 65 shows a selectable mixer which can be used to combine the frequency signals to produce various coloration of the sound. The output of the mixer is thèn attenuated as desired by a suitable circuit to control loudness r as shown by block 70.
While I have shown and described certain present 10 .

preferred embodiments of the invention and have illustrated a present preferred method of practicing the same it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied with the scope of the following claims.

11 .

Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for producing a wound string for a voltage controlled stringed instrument which utilizes resistance wires as strings to control the frequency of electronically generated sounds comprising the steps of:
tightly winding well insulated resistance wire about a core, dipping said wound string into a suitable resin, and removing said insulation and resin from the outer surface of said wound string.
2. A method for producing a wound string according to claim 1 wherein said core is a steel wire.
3. A method for producing a wound string according to claim 1 wherein said resin is epoxy or polyurethane.
CA000519926A 1983-10-31 1986-10-06 Electronic musical instrument Expired CA1237302A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA000519926A CA1237302A (en) 1983-10-31 1986-10-06 Electronic musical instrument

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA000440085A CA1216182A (en) 1983-10-31 1983-10-31 Electronic musical instrument
CA000519926A CA1237302A (en) 1983-10-31 1986-10-06 Electronic musical instrument

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
CA000440085A Division CA1216182A (en) 1983-10-31 1983-10-31 Electronic musical instrument

Publications (1)

Publication Number Publication Date
CA1237302A true CA1237302A (en) 1988-05-31

Family

ID=4126413

Family Applications (2)

Application Number Title Priority Date Filing Date
CA000440085A Expired CA1216182A (en) 1983-10-31 1983-10-31 Electronic musical instrument
CA000519926A Expired CA1237302A (en) 1983-10-31 1986-10-06 Electronic musical instrument

Family Applications Before (1)

Application Number Title Priority Date Filing Date
CA000440085A Expired CA1216182A (en) 1983-10-31 1983-10-31 Electronic musical instrument

Country Status (1)

Country Link
CA (2) CA1216182A (en)

Also Published As

Publication number Publication date
CA1216182A (en) 1987-01-06

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