US2254840A - Electric musical instrument - Google Patents

Description

p 1941- G. w. DEMUTH 2,254,840

ELECTRIC MUSICAL INSTRUMENT Filed Sept. 30, 1939 Enventor (Ittorneg Patented Sept.

Galan w. Demuth, N. 1., assignor to Radio Corporation of America, a corporation of Delaware Application September 30,1939, Serial no; 291,230

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This invention relates to an electric musical instrument and more particularly to an instrument of the general type oi a vibraharpor chime in which a vibrating "bar is used as a source of the tone. Y In the present apparatus,

provided. v

In prior art ,apparatus of the type described, vibrating .members .have been provided from which the vibrations could be picked up electrii cally and the vibrations were produced either mechanically or electrically. The iorm'of pickups-used were either electromagnetic or electrostatic. The sounding the vibrating member was accomplished by striking it with a hammer orplucking \itwith an appropriate pick or, in some instances, by means of an electric driver which caused regenerative oscillations. In 'the latter form or the deviceflthe" tone builds up gradually and no sharp attack can be secured.

In the striking or pluckingqorms of sounding mechanism, the sharp attack can be secured, but, when used in conjunction with an electrical pickup and an amplifier, the note sounded at the time oistriking is usually quite harsh and containsmany dissonant harmonics.

In, the present apparatus, I provide two me chanically coupled vibrating members, one oi which is struck or plucked and the other of which is adapted to operate the electrical pickup. The mechanical coupling between the elements is so constructed, preferably by providing consider- Another object oittheinvention is to provide.

animproved method of actuating the vibrating element'in an instrument oi the class described. Another object of the invention is to provide a double vibrating element the segments of which may betuned'to' diiierentclosely adiacent irequencies so-..tha.t beats may be secured.

Another. object of the invention is to provide an improved striking. mechanism for electrically striking the-vibratable member with a predetermined force. W, Other and incidental objects of the invention v The a novel form of vi- 1 brating element is used and a novel method of striking or sounding the vibrating element is.

-a readingbi the specification and an inspection V of the accompanying drawing in which Figure l is a side view partly in section ,0! one form of the inventionwith a mechanical pluck- 5 ing mechanism; and

Figure 2 is a similar view 6: a second form oi the invention with an electrical striking mecha-' nism 10 shown in Fig. 1:

The vibrating member is composed of two segments of a bar l0 and H, which are respectively tuned by the adjustable weights 12 and i3 adapt ed to be secured in appropriate locations on the 15 posed of segments 10 and H, is secured in the block II by the screw It or, if desired, the bar may be soldered into the 'block l4 after being located in the proper position. The block I 4 is in turn secured to the relatively heavy members l5 and I6 which are rigidly securedto the side plates ll and the base i8. Y

when the member I0 is vibrated transverselm;

a'suflicient quantity of the vibration is transmitted through the block it to the segment to cause the segment II to vibrate. If the members Ill and II are exactly in tune with each othenthe member Ill may be plucked or struck quite'sharply and the member II, in vibrating in sympathytherewith, will produce a uniform vibration without the'sharply. struck note or the dissonant harmonics of the plucked member Hi being( produced thereby. If, however, the members I 0 and II are slightly out of tune with each other, the 'same efiectis produced as far as the strike note is concerned, but the continued vibrations produce the well-known effect of beatand the pickup coil 22 willpick up the viebrations oi the segment II as modified by these 40 beats. r The tone in this caseis similar to that 0! a vibraharp or vibraphone. In either case,

' the objectionableefiects of the strike note are avoided.

In order to cause vibration of the segment It,

I have provided a cam I! which deflectsand'then suddenly releases the end of the segment ll.

' This cam is may be mounted on an appropriate mounted side by side with appropriate cams ll mounted in such angular relation on the sh'ait 'ilasto sired.

produce the tones in any sequenceydemagnetic pickup mechanism is duite simiwill be apparent'to those skilled in the art upon lar to that shown and' described in my 1 Referring first to the form of the invention bars by the screws in the weights The bar, comtion Serial No. 248,542, filed December 30, 1938 (RCV D-6515). In this pickuparrangement, the pickup coil 22 is mounted on a soft iron member 23, which is magnetically connected with and mounted on a small bar magnet 24, preferablyof an appropriate magnetizable alloy. This -magnet 24 is carried 'in a supporting tube 25,

is immediately withdrawn, preventing striking the member ID a second time, by the springs 39, carried by. the member 40, and the spring 15,

. which lifts the member 40 when the current ment ll of the vibratable member may be substantially the same as shown in Fig. 1 and tuned in the same way by the weight [2. Likewise, the supporting block M, the clamp screw l4, and the massive supporting block l are substantially the same. chanical and electrical shielding, however, I pro-' vide a more massive partition 32 carried by the side wall l1 and the base 3. The magnetic pickup elements 22 to Mi inclusive are likewise similar to those illustrated in Fig. 1 and require no further description.

The vibrating element the vibrating element ll. made from an appropriate springy magnetic material, such as piano wire, and is secured to the end of the segment by means of the block 42 and the screws 43 and 44. This member 3i is made very thin in relation to the member ill in order that vibrations of a considerably greater amplitude may be caused therein. Likewise, the mounting of the block 42 at a slight distance from the rigid block l4 tends to increase the amplitude of the vibrations of the member 3|. This member 3|, being very light, is not tuned in the 3| is substituted for same manner as the segment I I in Fig. 1, but is preferably tuned by grinding oi the end until the frequency of vibration is sufiiciently sharpened. If a little too much should happen to be ground from the end of the member 3|, the pitch may be slightly flattened by, for example, afiix ing a small drop of solder which may then be scraped until it has lowered the pitch only the required amount. The entire connection including the block 42, the screw 44 and the screw 43 should, after assembly, be covered with a layer of wax fused into place in order to prevent any buzzes or other undesired noises due to the rela: tive vibration of any of these parts.

The striking mechanism for this form of the invention includes a heavy magnet 34 supportedon appropriate posts 35 and adapted toattract an armature ,3 6. This magnet and armature may be of the type commercially used in relays.

' The armature 36 carries a. bent arm 40 which in turn supports the hammer 33 and the hammer arm 31 by the pivot 38. The hammer arm 31 is held up against the felt block by an appropriate spring 39. When the circuit is closed, passing current through the magnet 34, the armature 33' is drawn forcibly toward the' magnet, throwing the hammer 33 downwardly. When the armature 36 strikes the face of the magnet, the hammer 33, due to its momentum, continues tomove downwardly against the pressure of the spring 39 until it hits the striking member ID. When the hammer 33- strikes the member ID, it bounces and In order to secure more adequate meversely.

This element 3! is 1. Apparatus of the .class described including a vibratable tone-producing member, an electric pickup in cooperative relation with said member, a second vibratable member in substantial alignment with and coupled to said tone-producing member, massive means rigidly coupled to said members adjacent their junction point, and means for vibrating said second member trans- 2. Apparatus of 'the class described including a vibratable tone-producing member, an electric pickup in cooperative relation with said member, a second vibratable member coupled to said toneproducing member, and means for vibrating said second member transversely, said members being substantially in alignment coupled at their adjacent ends and'having theirouter ends free to vibrate transversely.

3. Apparatus of the class described including a vibratable tone-producing member, an electric pickup in cooperative relation with said member, a second vibratable member coupled to said toneproducing manner, and means for vibrating said second member transversely, the member in 00- operative relation with said pickup being thirmer than the other member.

4. Apparatus of the class described including a' vibrate transversely, the member in cooperative relation with said pickup being thinner than the.

other member. a

5. Apparatus of the class described including a vibratable tone-producing member, an electric pickup in cooperative relation with said member,

a second vibratable member coupled to said toneproducing member, means for vibrating said second member transversely, the member in cooperative relation with said pickup being thinner ber, and massive means rigidly coupled tosaid members adjacent their junction point.

GALAN W. DEMUTH.

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