Patent Application
20150128783
This invention relates generally to stringed instruments, and more especially to guitars and fretted instruments.
In fretted stringed musical instruments, one or more strings are stretched under tension across the main body of the instrument, which amplifies the sound of the vibrating string. One end of the string is anchored at one side of the main body (often referred to as the ‘bridge’), and the other end is anchored at the end of the neck furthest from the main body (often referred to as the ‘nut’). A series of ridges (or ‘frets’) running transverse to the neck (the ‘fretboard’) are positioned at various intervals, underneath the strings. The strings do not touch the frets, even during vibration.
The pitch of a plucked string is determined by the relationship of the tension of the string, its mass per unit length (which is a function of the string's diameter), and the length of the string available for vibration (effective length). This length is the distance between the bridge and the nut.
On fretted stringed musical instruments, one of the player's hands is used for plucking or striking the strings while the other one may press upon one or more strings of the instrument with one or more fingers to cause the string to engage the frets along the neck of the guitar or other musical instrument. This procedure reduces the effective string length to the distance between the bridge and the fret, allowing the musician to change the pitch as called for by the musical score.
Stringed instruments are normally played in a standard tuning; when no strings are depressed upon frets (termed ‘open’ strings, played without fingering), they are under defined tension to produce a standard series of pitches. A device called a ‘capo’ (or ‘capotasto’) is often used to mechanically depress the strings onto a fret, effectively shortening the length of the strings. Most capos depress all strings, though there is occasionally a need for only a selection of stings to be depressed. This makes a greater variety of sounds available to the musician.
There are a great number of patents issued for innovative capo designs, though fewer for capos that allow only a selection of strings to be depressed (e.g. U.S. Pat. No. 5,623,110, NL8900025). One major drawback of such designs is that although they allow a selection of strings to be depressed, the capo is only fitted across one fret, and so it is impossible to depress different strings at different frets without using multiple capos, which would impede playing. One capo design allows different strings to be depressed at different frets (GB2349010), but this would also impede the fretting hand as it moves across the device.
Further innovations have involved the use of a multitude of individual capo elements that depress only one string each, and can be positioned anywhere along the neck of the instrument (U.S. Pat. No. 6,998,526, CA2244647, CA2213187, U.S. Pat. No. 6,013,868, GB2393315, U.S. Pat. No. 5,056,397). These designs all focus on the mechanical means of depressing the string onto the fret, and all require the modification of the instrument itself, by requiring magnets within the instrument neck (U.S. Pat. No. 6,998,526, CA2244647, CA2213187, U.S. Pat. No. 6,013,868), mechanical fixings (GB2393315), or specially profiled frets (U.S. Pat. No. 5,056,397).
There remains a need for a means of mechanically altering the pitch of selected individual strings, at different positions along the instrument neck, which does not impede the fingering hand movement along the neck, and does not require any modification of the instrument itself.
The invention relates to a device for mechanically altering the pitch of selected individual strings of a fretted stringed musical instrument such as a guitar. This is accomplished by shortening one or more strings of the musical instrument to produce a pitch different than its usual unaltered frequency.
According to one embodiment, the mechanical devices, or fixed capo elements, of the invention which are the means to mechanically alter the pitch of a string, comprise a multitude of specially designed blocks placed upon the fretboard, abutting the appropriate fret to give the desired pitch. Each block has a groove formed into the top into which the string is wedged, thus preventing vibration. In the preferred embodiment, each capo element has a groove corresponding to the diameter of the specific string for which it is to be used. Each block is secured temporarily to the fretboard using an appropriate adhesive. The string is secured at that position until the capo element is removed. The capo elements can be placed at any point along the fretboard. To remove the capo element from the fretboard, it is pulled away and the string removed from its groove. In the preferred embodiment, the capo elements may be reapplied, though it may be that these elements are disposable, and a new set must be used every time the positions are changed.
It is an object of the subject invention to provide a device for mechanically altering the pitch of selected individual strings of a fretted stringed musical instrument such as a guitar.
It is another object of the subject invention to provide a mechanical device such that various lengths of a string of a stringed instrument can be fixed for different pitches.
It is still a further object of the subject invention to provide a mechanical device for each individual string of the instrument, and to provide a complete pitch selection for the strings of a fretted stringed instrument.
It is still another object of the subject invention to provide a mechanical device for varying string pitch of a fretted stringed instrument that is affordable, does not impede the musician's playing hand motion and does not require any modification to the instrument.
For a more complete explanation of the present invention and the technical advantages thereof, reference is now made to the following description and the accompanying drawing in which:
a shows an isometric projection of an alternative embodiment of the capo element.
Embodiments of the present invention and their technical advantages may be better understood by referring to
The capo element (1) is made of a hard plastic so as not to dampen any vibration and deaden the tone. The element has an adhesive base with minimal thickness, in order to transfer string vibrations through the fretboard and back to the instrument body.
The proximal portion of the capo element (1) is so shaped as to overhang the raised fret (2). This ensures correct positioning of the capo element, so trapping the string at the same length as would otherwise have been achieved by fretting the string in the regular manner. Thus the overhanging portion is located nearest the bridge with the remaining part of each capo element extending towards the nut.
The groove (5) in the top of each capo element is so shaped as to trap the string with friction alone. Different strings have different diameters, and so the groove (5) must be correctly sized to each string to create an interference fit, and not allow any movement of the string. As such, a different width groove is necessary for each string, particularly when used for acoustic guitars where the diameter difference is relatively large.
Each capo element (1) is wide enough to allow multiple elements to be used side by side on the same fret. Each capo element (1) has sufficient length to allow a strong adhesive fixing to the fretboard, but is short enough to be used further up the neck of the instrument where the frets are closer together.
a shows an alternative embodiment of the capo element whereby the string is secured by three small blades (6) arranged along the line of the string to replicate the groove (5). This replaces the narrow groove, which can be difficult to manufacture.
Strings for instruments are sold either singly or in sets. Sets of strings contain all the strings or a subgroup of strings used in the instrument. Strings are available in different weights from light to heavy and the gauges of the strings in a set of a given weight are often standard. Likewise the capo elements can be sold singly or in sets. When sold in a set, each element of the set may have grooves may have the same widths as the gauges of the corresponding standard string set. When sold singly, the width of the groove of a capo element should correspond to the standard gauge of a string.
Usually the capo elements will be marked in accordance with the strings they are to be used with. Thus, a set of capo elements may be marked for use with a given weight of strings for a given instrument. By way of example, a set of capo elements might be sold for use with light weight steel strings for an acoustic guitar and obviously the individual capo elements in that set will have grooves of a width corresponding to the gauges of the various light weight steel strings. When sold individually, the capo element may be marked with either the width of the groove (or the gauge of the string it is to be used with) or with both the type of string (e.g. the A string, the G string etc) and the weight of the string.
Instead of being marked, the capo elements may be coded, e.g. colour coded, or may be contained in packaging that is marked or coded.
Although the capo element so far described has a groove of fixed width, it is possible for the walls of the groove to move towards and away from each other to allow the easy fitting of the string within the groove and the subsequent clamping of the string. This can be achieved by making one of the sidewalls spring-loaded so that it is biased by a spring towards the other wall but can be moved away to release the string. A further alternative is for one wall to be moved by a screw thread towards or away from the other. A still further possibility is that the wall is movable by means of a slider and an associated sloping cam surface attached to the movable wall; the slider can be moved along the length of the cam surface in one direction the slider to cause the cam surface to urge the walls together while pushing the slider in the other direction allows the walls to be moved apart.
While a preferred embodiment has been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather it is intended to cover all modifications and alternate constructions falling within the spirit and the scope of the invention as defined in the appended claims.
