United States Patent 3851558

A mechanical fretting device is detachably placed over a predetermined number of frets and extends across all strings of the finger board of a guitar or other stringed fretted instrument. A card contains slots which determine which strings are to be engaged with each fret to determine a chord, different cards being used for different chords. The user can press a single button with his fingers and move a lever with his wrist whereby when he strikes the strings with his other hand in conventional manner, the chord is sounded.

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International Classes:
G10D3/08; (IPC1-7): G10D3/00
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US Patent References:
1853999Musical instrument1932-04-12Solenberger

Foreign References:
Primary Examiner:
Wilkinson, Richard B.
Assistant Examiner:
Gonzales, John F.
Attorney, Agent or Firm:
Jay Jr., Theodore
Having thus described this invention, what is asserted as new is

1. A mechanical chord fretter for use with a string carrying fretted finger board of a musical instrument such as guitar, said fretter comprising:

2. The fretter of claim 1 wherein the push buttons are spring loaded.

3. The fretter of claim 2 wherein said cards have holes and slots therein, the pattern of holes and slots determining which assemblies are selected for actuation.

4. The fretter of claim 3 wherein each card has circular holes and slots with semi-circular ends.


My invention is directed towards a device which makes it possible for an individual to play chords on a fretted stringed instrument, typically a guitar, even though this individual is unwilling or unable to learn to play chords by proper manual finger placement.

In accordance with the invention, a device is detachably secured to the finger board to cooperate with a selected group of frets and all strings.

The device has a first main section containing a plurality of buttons, each of which enables the user to select a different chord to be fretted.

The device has a second main section containing a plurality of spring loaded plunger assemblies which can be actually pressed down upon the strings to fret the desired chord.

The device has a third main section containing a plurality of differently perforated cards with cords attached, the arrangement of perforations in each card uniquely determining a different chord.

Each plunger assembly includes a vertical hollow tube, closed at one end, in which a tension spring and a plunger are disposed. Typically there are 24 assemblies, one for each of the first four fret positions for each of the six strings of a guitar.

Each assembly passes through an aligned column of perforations in a vertical stack of horizontal cards. Each card has a pattern of 24 perforations in an arrangement of circular holes and semi-circularly ended slots.

To one end of these cards is attached a tension spring in the form of an elastic cord and at the other end is an inelastic cord. Each of these last cords is connected to a single vertical pushbutton labelled with a coded name identifying a chord. Each pushbutton is held in the up position by a compression spring. Thus, when a pushbutton is pushed, the card whose perforation pattern corresponds to the chord on the button is moved along its own horizontal plane. When the button is released, it returns to its original position and the card is drawn back to its original position.

The plunger assemblies which pass through the perforations can be moved horizontally and are spring loaded in vertical positions. Whenever a card is moved horizontally, the assemblies passing through the holes in that card will also move horizontally. The assemblies which pass through the slots in that card will remain vertical.

Thus, the act of depressing a chord button moves a perforated card horizontally and forces a certain pattern of plunger assemblies corresponding to the chord to be moved horizontally in the direction of motion of the card. Releasing the button allows the card and the displaced assemblies to return to their original vertical positions, the undisplaced assemblies remaining fixed.

A predetermined number of comb-like assemblies, typically four, one for each fret, are disposed underneath the cards, each assembly being disposed with its long axis parallel to the frets and associated with the corresponding fret. Each assembly can be rotated about its long axis and is held in horizontal position by torsion springs. Inelastic cords are connected to each assembly at one end and at the other end to a wrist operated lever. When the lever is pressed, tension on the cords forces the assemblies to rotate together. Each of these combs have a number of depressions, typically six, one for each string, capable of engaging the plungers.

Normally the plunger assemblies are out of the rotational range of the combs, but when a cord button is pushed, some plunger assemblies are brought into the range of the depressions in the combs. When the wrist lever is pushed, the depressions of the combs engage the displaced plungers and these last are pressed down upon the strings of the instrument to fret the desired chord. Releasing the wrist lever allows the combs to return to their original positions, whereby the plungers are pulled back up into the assembly tubes away from the strings.


In the drawings:

FIG. 1 is a side view of the invention in use;

FIG. 2 is a top view thereof;

FIG. 3 is a side view of a chord button assembly;

FIG. 4 is a top view of a single perforated card;

FIG. 5 is a side view of a plunger assembly as engaged by a comb; and

FIG. 6 is a top view of a comb.


Referring now to FIGS. 1-6, chord buttons 1 normally held in raised positions by springs 2 are attached to cords 3. Cords 3 pass over rollers 4 to perforated cards 5. Each card has a pattern of circular holes 6 and slots with semi-circular ends 7. Through these perforations pass plunger assemblies 8 consisting of hollow elongated tubes 8A closed at one end with torsion springs 9 and plungers 10 disposed therein.

When a button is depressed, an appropriate card moves horizontally to the left and carries with it only those plunger assemblies which passed through holes in the card.

Depression of wrist operated lever 11 pulls cords 12 which are attached to combs 13, causing these combs to rotate. Those plungers which have been displaced by the horizontal motion of the card are now engaged by the depressions of the combs and are pressed down upon the strings 14 of the instrument, fretting them.

When the lever is released, the combs return to original horizontal position and the plungers are pulled up into the tubes.

Release of the button enables the cards to move back, carrying the plunger assemblies back to their original positions, the process being aided by plunger assembly tension springs 16.

While I have described my invention with particular reference to the drawings, such is not to be considered as limiting its actual scope.