US 2252708 A
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Description (OCR text may contain errors)
Aug. 19, 1941. w. L. DOUDEN ELECTRIC PIANO CONSTRUCTION Filed Dec. so, 1958 Patented Aug; 19, 1941 ELECTRIC PIANO CONSTRUCTION William L. Douden, Philadelphia, Pa, assignorfto Radio Corporation of America, a corporation of Delaware Application December 30, 1938, Serial No. 248,563
This invention relates to the construction of electric pianos or pianos in which the vibration of the strings is electrically converted into sound, and pertains particularly to the frame construction of such devices.
In the prior art, it has been thought necessary to mount the bridge of an electrical piano in such a manner that it could vibrate more or less freely or somewhat in the fashion of the vibration of the bridge of a conventional piano. Such a mounting of'the piano bridge has been found unnecessary and, in fact, a comparatively rigid mounting of the bridge is described and claimed in Demuths application Serial No. 237,001, filed October 26, 1938 (RCV D6348). The said Demuth application points out the advantages of rigid mounting of the bridge, such as greater time of vibration of strings, etc. In the said Figure 1 is a rear view of a piano frame casting with the bridge and pickup units attached in accordance with the invention, and
Figure 2 is a section taken along the line 22 of Figure 1.
The usual castiron piano frame is indicated at 10. The particular frame shown in the drawing is one adapted to use in the small upright type of pianos. "This frame carries the usual wrest plank II which carries the tuning pins l3 connected to the strings l2. As shown in Figure 2, the strings I! are supported by the bridge l5. This bridge, instead of being supported upon a sounding board as .in conventional piano construction, is supported directly upon the brackets i6 and H. Both the bracket l6 and the bracket therefore, not adjustable in relation to the frame.
Demuth application, the bridge is shown and de- 1 scribed as mounted on metal brackets secured-to the piano frame, and the mounting of magnetic pickups is disclosed as being accomplished on somewhat similar brackets.
In the said Demuth construction, the frame andbracket assembly is more or less built up. In a piano construction in accordance with the present invention, the brackets for supporting the bridge and also for supportingthe electromagnetic pickups are cast integral with the piano frame, in order to prevent any possibility of their vibration or displacement in relation to the piano frame. This arrangement not only accomplishes all the results of the Demuth construction but, in addition, it provides a predetermined fixed location for the bridge and for the pickup units and positively precludes their subsequent displacement or disarrangement.-
One object of the invention'is to provide an improved piano construction;
Another object of the invention is to provide a piano frame construction ofgreater rigidity than heretofore provided;
Another object of the invention is to provide a comparatively simple and inexpensive construction of an electric piano.
Another object of the invention is to provide means for positively holding the strings, bridge and electrical pickups of a piano in predetermined fixed relation to each other;
Other and incidental objects 01' the invention will be apparent to those skilled inthe art from a reading of the following specification and an inspection of the accompanying drawing, in which The faces of these brackets toward the strings and bridge may, if desirable or necessary, be finished off uniformly by planing or milling their surfaces into a single plane, but thisis usually unnecessary. The bridge i5 is as usual composed of one or more strips of hardwood and is firmly secured to the brackets l6 and I1 by appropriate screws 20. It will be apparent that, due to the fact that the brackets I6 and I! are cast integral with the frame i0 and the bridge is secured firmly to these brackets, the bridge will be incapable of any material vibration and, therefore, the energy of the vibrating strings will not be dissipated through the bridge.
The strip 18 supporting the pickup elements i9 may be mounted on the brackets I6 and il in the same manner as the bridge IS. The pickup strips i8 may be divided into as many sections as is convenient, as illustrated, for example, in Figure 1. Since these pickup strips are mounted rigidly upon the same brackets as the bridge i 5, it will be apparent that it will be substantially impossible for the pickups and the bridge to get out of adjustment in relation to each other. Since the bridge l5 supports the strings I2 and the pickup strip. i8 is supported by the bracket [8 near to the bridge ii, the relation between the pickups and the strings I! will be predetermined by the construction of the pickup strips and by the height of the bridge. The construction prevents any tampering with the relation between the pickups and the strings by persons tuning the piano or by others who may have occasion to handle the instrument. The pickups used are preferably of the type shown and described in Demuth application Secent to and spaced from said bridge and adja cent to the plane of strings supported by said bridge.
2. In a piano, a cast frame, bracket members integral with said frame and extending inwardly therefrom at spaced intervals, a bridge immovably fixed to said bracket members for supporting piano strings, and electrical pickup devices immovably supported on said bracket members adjacent to and spaced from said bridge and adjacent to the plane of strings supported by said bridge.
WILLIAM L. DOUDEN.