Musical stringed instrument capable of being played with one hand

A musical stringed instrument including a control circuit that provides a means for playing with one hand. The control circuit is either integral with or external to the musical stringed instrument. One hand operation is accomplished by selectively bringing one or more of the strings into electrical contact with any one or more electrical contacts or frets or by depressing any one or more switches corresponding to each string. A striker pad impacts the chosen string causing it to vibrate. Variation in the notes is accomplished in a manner consistent with two handed operation of the musical stringed instrument.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates, in general, to musical stringed instruments and 
more particularly to electrical guitars and the like that include a 
control circuit that permits playing with one hand. 
2. Description of the Prior Art 
Conventional stringed instruments, such as guitars and banjos, require the 
use of two hands to operate. A first hand causes one or more strings to 
come into contact with a fret to change its effective length thereby 
changing the sound pitch created when a second hand causes one or more 
strings to vibrate. Difficulty arises when an operator has only one 
functioning hand or desires to use one of their hands to perform other 
tasks while playing a musical stringed instrument, such as the playing of 
more than one instrument at the same time. 
Attempts have been made to permit an operator to play a musical stringed 
instrument with one hand by providing a means to simultaneously vibrate 
one or more chosen strings and change their effective length with one 
hand. Other inventions that enable a player to operate a musical stringed 
instrument with one hand require either the use of one's foot to provide 
the function of the second hand or a means to turn the electronic pickups 
either on or off for individual strings. 
The present invention enables a player to operate a musical stringed 
instrument with one hand only and does not require any other external 
input and can be used on musical stringed instruments that do not have 
electronic pickups. Further, the present invention is simple to install 
and less costly than other attempts to create a musical stringed 
instrument capable of being played with one hand. 
SUMMARY OF THE INVENTION 
In carrying out this invention, in one form thereof, a musical stringed 
instrument is provided which includes an instrument body having a fret 
board. The fret board includes a plurality of electrically common and 
electrically conductive frets spaced along the fret board. One or more 
electrically isolated and electrically conductive vibratory strings are 
connected to the instrument body in laterally spaced relationship and are 
held in tension over and in close proximity to the plurality of frets. An 
identifying means generates a string signal when any one or more of said 
strings have been placed in electrical contact with any one or more of 
said frets or when an electrical switch corresponding to each of the 
strings is operated. A means for striking each of the strings responds to 
the string signal by causing each respective string to be struck, thereby 
vibrating the string. In one form of the invention, the identifying means 
is an electrical circuit that includes a schmitt trigger, a monostable 
multivibrator and a solid state relay and generates the string signal and 
includes an electromagnetic solenoid connected to a rocker arm that 
strikes each string. In another modified form of the invention, the 
operator can cutoff lower string operation by triggering a predetermined 
combination of solenoids. A multiple input handgate could be used to 
predetermine the combination that would prevent one or more of the lower 
strings from being operated or cutoff as it is referred to here.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the Figures where like reference numerals have been used 
throughout to designate like parts, FIG. 1 shows an electrical guitar B of 
conventional design with the present invention A installed thereon. The 
guitar B comprises a fret board D connected to and extending outwardly 
from a body C. Strings G1 to G4 extend along and are connected to fret 
board D and are connected to first side 10 of body C through bridge E. The 
installation of the present invention A is illustrated in FIG. 1 and shows 
striker pads H1 to H4 located in close proximity to strings G1 to G4 
respectively. Rocker arm relays J1 to J4 are connected to and operate 
striker pads H1 to H4 respectively. When any one or more of strings G1 to 
G4 are depressed and brought into electrical contact with any one or more 
of frets 68, a string signal is generated corresponding to the depressed 
string. The string signal activates the corresponding rocker arm relay J1 
to J4 causing striker pads H1 to H4 to impact upon strings G1 to G4 
respectively, thereby causing strings G1 to G4 to vibrate. Outboard 
control circuit F is connected to and powers rocker arm relays J1 to J4 
through interface cable 12. Outboard control circuit F is connected to 
conventionally available electrical power through power cable 14. Outboard 
control circuit F can be turned off or on by manipulation of foot switch 
16. Thumb buttons 20 are mounted on top side 22 of fret board D and are 
described in FIG. 5. 
FIG. 2 shows an exploded view of rocker arm relays J1 to J4, mounting 
bracket 26 and striker pad H1. Mounting bracket 26 is secured to first 
side 10 of guitar body C. Rocker arm relays J1 to J4 are mounted to 
mounting bracket 26 by screws 40. Rocker arm relays J1 to J4 are identical 
and are shown in various stages of disassembly and comprise rocker arm 28, 
coil 96 and coil core 32. Coil 96 comprises a plurality of turns of wire 
and coil core 32 is comprised of magnetic material and is of conventional 
design. Rocker arm 28 is pivotally connected to rocker arm J4. Rocker arm 
28 pivots to make contact with coil core 32 at point 30 where a thin layer 
of damping material is located. Referring now to rocker arm relay J1, 
striker pad H1 is connected to rocker arm 28 and upon activation of rocker 
arm relay J1 in response to a string signal, striker pad H1 will impact 
string G1 and cause string G1 to vibrate. Elastic material 34 .acts as a 
return spring for rocker arm 28 and can be made of rubber or spring wire. 
FIG. 3 illustrates an alternate means for striking strings G1 to G4. 
Alternate solenoids K1 to K4 are used when a lateral strike of the strings 
is needed such as when modifications to an existing musical stringed 
instrument is not practical or desired. In FIG. 3, alternate solenoids K1 
to K4 are identical and K4 is illustrated in an exploded view. Solenoid K4 
comprises solenoid body 50, actuator 46, coil spring 48, striker arm 44 
and striker pad 62. Solenoid body 50 is attached to mounting bracket 42 
through spacer 54, mounting bracket 56 and mounting block 64 by machine 
screw 52 and is positioned adjacent string G4 (not shown). Striker arm 44 
is attached perpendicular to actuator 46. Striker pad 62 is attached to a 
first end of striker arm 44 and a second end of striker arm 44 is located 
under spacer 54 upon assembly and is free to slide thereunder. Machine 
screw 52 is adjusted to position striker pad 62 next to but not touching 
string G4 (not shown). Upon activation of solenoid K4 in response to a 
string signal, actuator 46 is pulled into solenoid body 50 causing striker 
pad 62 to impact string G4 (not shown). Coil spring 48 returns striker arm 
44 to its starting position. 
FIG. 4 illustrates the electrical control circuit F of the present 
invention. Fret board D comprises a plurality of electrically conductive 
frets 68 spaced along its length and a plurality of strings G1 to G4 
spaced in lateral relationship along fret board D and perpendicular to and 
in close proximity to frets 68. Frets 68 are electrically common and are 
held at ground potential 70. A string signal for strings G1 to G4 is 
generated when any one or more of strings G1 to G4 is brought into 
electrical contact with any one or more of frets 68. Response to string 
signals from strings G2 to G4 is identical and the response for one string 
signal is described herein with the intent to describe the response to the 
string signal for each string G2 to G4. Response to a string signal from 
string G1 is slightly different as is described below. Strings (G1 to G4 
are electrically energized by separate power supply 94 through resistors 
T1 to T4. Strings G1 to G4 are each connected to separate schmitt triggers 
72 and to multiple input nandgate 74 through signal shaping resistors R1 
to R4 and capacitors U1 to U4. A string signal from strings G1 to G4 
initiate schmitt triggers 72 which drive monostable multivibrators L1 to 
L4, or one shots as they are sometimes referred to in the industry. 
Monostable multivibrators L1 to L4 generate one pulse with a constant 
pulse width, Potentiometers 88 control the pulse width of each monostable 
multivibrator L1 to L4 and is adjustable. Output Q of monostable 
multivibrators L2 to L4 are connected to the input of buffer/drivers N2 to 
N4 respectively. Output "Q not" of monostable multivibrator L1 is 
connected to one of the inputs of multiple input nandgate 74. String 
signals from other strings G2 to G4 enter multiple input nandgate 74 
through signal shaping resistors R1 to R4 and capacitors U1 to U4. The 
output of multiple input nandgate 74 is connected to the input of 
buffer/driver N1. The output of buffer/drivers N1 to N4 energize solid 
state relays P1 to P4 that drive rocker arm solenoids J1 to J4 or 
alternatively solenoids K1 to K4. The function of multiple input nandgate 
74 is to deactivate string G1 when strings G2 to G4 are simultaneously in 
electrical contact with any one or more of frets 68. Diodes X1 to X4 are 
connected between the input of each solenoid and ground 70 and capacitors 
Y1 to Y4 are connected between the output of each solid state relay P1 to 
P4 and power supply 92, respectively, to suppress electrical noise. Power 
supply 92 provides the energy for solid state relays P1 to P4 and rocker 
arm relays J1 to J4, or alternatively for solenoids K1 to K4. 
FIG. 5 illustrates a section of fret board D with thumb buttons 20. Frets 
68 are laterally spaced perpendicular to and along fret board D and are 
electrically common. Copper tape, 76 or other conductive material extends 
along the length of fret board D and is electrically connected to each 
fret 68 by solder joint 78 or other suitable means. Thumb buttons 20 are 
provided for each string G1 to G4 and are attached to fret board D with 
hook and loop tape or other suitable means. Wire 84 illustrates a 
functional electrical connection between one thumb button 20 and 
electrical output connection 83. Wire 85 illustrates a functional 
electrical connection between one thumb button 20 and string G4. Thumb 
buttons 20 are electrically connected in similar fashion between each 
string G1 to G4 and multiple input nandgate 74 as illustrated in FIG. 4. 
Thumb buttons 20 are electrical switches 90 that when depressed generate a 
string signal that causes each respective string to be impacted by striker 
pad H1 to H4 as illustrated of FIGS. 4, 3 and 2. 
In the specific embodiment illustrated in FIGS. 1 through 5, a musical 
stringed instrument can be operated with one hand. An operator creates a 
note when a string signal is created which causes striker pad 62 to impact 
the desired string. A string signal is generated by either depressing a 
desired string G1 to G4 in such a manner that it comes into electrical 
contact with any one or more frets 68 or by depressing a thumb button 20 
corresponding to a desired open string G1 to G4. When all strings are 
selected at the same time, string G1 is prevented from being struck by the 
function of multiple input nandgate 74. It should be understood that other 
arrangements for deselecting a given one or more strings is contemplated 
by the inventor herein and the deselecting of string G1 is simply an 
illustration of the scope of the control option anticipated herein. Thumb 
buttons 20 can also function to generate multiple impact on a given string 
G1 to G4 by depressing it more than once whether string G1 to G4 is in 
electrical contact with frets 68 or is open. 
The invention described herein provides a reliable, simple, safe and easy 
method for playing a musical stringed instrument, such as an electrical 
guitar, with one hand. It is intended that the description should not act 
as a limitation on the scope of the invention disclosed, but rather is an 
exemplification of one embodiment thereof. Many other embodiments and 
variations are anticipated such as use on an acoustic guitar, variations 
in the control circuitry and use with more or less than four (4) strings. 
The scope of the invention should be limited only be the appended claims 
and not by the examples given.