GB603153A - Stringed musical instrument - Google Patents

Abstract

603,153. Stringed musical instruments. McBRIDE, J. W. Dec. 12, 1944, No. 24923. [Class 88 (ii)] In a stringed musical instrument such as a guitar, mandolin or violin cam means are provided for selectively moving frets into and out of contact with the strings to determine the length of the vibrating string portions. In a guitar, the frets are arranged under the strings 5, 6, 7, 8 in four series, Fig. 1. The frets are guided for movement into and out of engagement with the strings by guide plates 21, 22, Fig. 9, and are normally held out of contact with the strings by springs 41 engaging the plate 21 and a pin 40 on each fret. The frets of each series are urged towards the corresponding string by means of cam rods 54 provided with steep cam surfaces with the cam crests corresponding to the respective frets falling in a helical curve. Alternatively a continuous helical crest may be provided on each rod. The cam surfaces are made steep so that the frets will contact the strings with sufficient speed to cause them to vibrate without the aid of a plectrum. The sounds may be amplified electrically by apparatus including a pick-up P and mechanism for the control of volume and tone at 15 and 16 respectively. The cam rods 54 are controlled by keys 60 arranged to slide in a direction transverse to the strings. A key 60, when pressed, rotates the cam rod 54 by means of a spiral spring connection 56, Fig. 3, which returns the key to normal when pressure is released. Only'one of the four spiral springs is shown in Fig. 3. To facilitate setting of the keys 60, a lens 80 is provided through which transverse graduation markings on the keys can be viewed. In a modification, Figs. 13, 16, the rotatable cam rods are replaced by longitudinally movable rods 122 carrying cams such as 153. Each rod 122 can be pressed against the action of a spring 142 to bring the desired fret such as 150 into contact with the corresponding string 96. A key 148 is provided for each rod 122 and the setting can be viewed through a cylindrical lens 156. In another modification, the frets take the special form shown in Fig. 30. Frets 179 are supported end to end in a series under each string 165, Fig. 21. A cylindrical projection 201 fits into a corresponding socket 202- on the adjacent fret to form a hinge. The frets are restricted against lateral movement by the engagement of flanges 186 with the sides of a slot in the body of the instrument and they normally rest on plates 195 spaced sufficiently apart to pass the narrow extension 199. Upward movement of the frets is limited by plates 188. The arcuate pointer edges 200 of the projections 199 come into engagement with the helical like crests 206 on the cam rods 205 as the rods rotate. As a cam is rotated the frets of the series are in turn raised to contact the string and are then rolled to transfer the contact along the string and thereby produce a glissando effect. In this arrangement the keys 222 rotate the cam rods through racks 229 and pinions 230 against the action of springs 234.