US2201232A

US2201232A - Electrical musical instrument

Info

Publication number: US2201232A
Application number: US203241A
Authority: US
Inventors: Helberger Bruno
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-04-21
Filing date: 1938-04-21
Publication date: 1940-05-21
Anticipated expiration: 1957-05-21

Description

May 21, 1940. B. HELBERGER ELECTRICAL MUSICAL INSTRUMENT Filed April 21, 1938 3 Sheets-Sheet 1 Amplifier ENTOR ATTORNEYS May 21, 1940. B. HELBERGER ELECTRICAL MUSICAL INSTRUMENT Filed April 21, 1938 3 Sheets-Sheet 2 TOR BY 7' V 7 TToRNEYs May 21., '1940. a. HELBERGER ELECTRIC AL MUSICAL INSTRUMENT 3 Sheds-Sheet 3 Filed Apt-1141', 1939;

ENTOR Patented May 21, 1940 OFFICE ELECTRICAL MUSICAL INSTRUMENT Bruno Helberger, Frankfort-on-the-Main, Germany Application April 21, 1938, Serial No. 203,241

6 Claims.-

This invention relates to musical instruments and pertains more particularly to improvements in electronic musical instruments of the type illustrated in Lertes and Helberger Patent No. 1,847,119, dated March 1, 1932.

It is an object of the invention to provide an improved playing manual by means of which the performer may secure improved musical effects.

Other objects and advantages of the invention will appear hereinafter.

A preferred embodiment of the invention selected for purposes of illustration is shown in the accompanying drawings, in which:

Figure 1 is a perspective view showing the instrmnent as it may be applied as an attachment for a piano. 1

Figure 2 is a circuit diagram.

Figure 3 is a top plan view of the playing manual.

Figure 4 is a section on the line 4-4 of Figure 3.

Figure-5 is a section on the line 55 of Figure 3.

Figure 6 is an enlarged perspective view resistance bar.

Figure 7 is an enlarged section on the line 1-4 of Figure 4.

Figure 8 is a section on the line 8--8 of Figure 4.

Figure 9 is an enlarged top plan view of. one of the playing strips.

Figure 10 is a section on the line Ill-I0 of Figure 9.

Figure 11 is a section on the line I IH of Figure 9.

Figure 12 is an enlarged perspective view of one of the end blocks.

Figure 13 is an enlarged perspective view of a playing strip.

Figure 14 is an enlarged perspective view of the supporting strip assembly.

In the musical instrument .disclosed in the prior of the patent referred to, a thermionic tube oscillator is employed, and the pitch of the sound produced by said oscillator is controlled by varying the frequency of the said oscillator by varying the resistance of a circuit including said oscillator. The sai'd'resistance is varied by the performer by operating the fingers along a playing strip which short circuits more or less of the resistance. In addition, the playing strips were so arranged that it was possible for the performer to control the volume of the sound produced by varying the pressure applied to the playing strips by the fingers. Thus the performer is able to control with a single finger both pitch and volume of the sound produced.

According to the present invention all of the advantages of the previous instrument are retained, and certain improvements are added which facilitate the operation of the instrument. Referring to Figure l, the instrument is illustrated as it may be employed as an attachment to a piano, in order that the performer may be able to use one hand to play on the piano keyboard and the other hand to play on the manual of my instrument. In this form, as illustrated, the manual designated generally by numeral I may be mounted on the piano keybed, immediately in front of the keyboard. It will be understood, however, that the manual may be embodied in a separate instrument if desired.

In the manual illustrated for use as an attachmentfor a piano only two playing strips are provided, but it will be understood that as few as one or as many as ten playing strips may be provided depending on the purpose intended to be served.

The playing strips, designated by numeral 2, are preferably made of metal such as brass or stainless steel, and are provided with transverse ridges 3 forming frets which indicate to the performer the proper playing intervals. If desired, the upper surface of each playing strip may be painted with black and white markings, as shown in Figure 3, corresponding to the black and white keys of the piano. This facilitates the playing of the instrument by a pianist accustomed to a piano keyboard. The left end of. the playing strip is firmly anchored by bending it around a fixed strip 4, while the right hand end is tensioned by the leaf spring 5 which holds the strip taut and takes up any expansion.

The playing strips are yieldingly supported above the resistance bars 6 by means of rubber strips I and sponge rubber cushions 8 of such construction as to provide the desired touch" for the playing strips. For maximum facility in playing it is desirable that when the performer depresses a playing strip to make contact with the resistance bar, a moderate, but not excessive, finger pressure he required. It is also desirable that when the finger is lifted, the playing strip return quickly to normal position so that rapid successions of notes may be played. Finally it is desirable that the playing strips be restrained against transverse movement, or movement above normal playing level.

For these purposes the rubber strips I extend longitudinally parallel to the playing strips,

strips 1a and 12) being associated with the outer playing strip and strips 1c and 1d being associated with the inner playing strip. As illustrated in Figure 7 the opposed flanges 9 and I0 of rubber strips 10 and Id lie beneath the playing strip, while the other flanges II and I2 lie beneath the flange l3 of the casing and'the flange [4 of the fixed T-shaped bar l5 which separates the two playing strips. Similarly, the flanges l5 and ll of strips Ia and lb lie beneath the playing strip, and the flange l8 lies beneath the flange IQ of bar I5. In this case, however, the flange is extended outwardly and downwardly to form an apron 2|, which is preferably backed, for stiffness, by a strip 22 of canvas or other suitable material. This construction is desirable because the outer playing strip is frequently operated by the thumb of the performer and the outside panel 23 of the casing must be depressed, as shown, in order not to interfere with proper p y The rubber strips are each provided with vertical ridges 24 and the edges of the playing strips fit into grooves 25 formed in the sides of ridges 24. In order to provide even more positive connection between the playing strips and the rubber strips, the playing strips may be provided with ears 25 which fit into apertures in the rubber strips.

Preferably, the ridges 24 are provided with humps 21, located opposite the positions on the playing strips corresponding to the black keys of a piano keyboard, in order that these positions may be located by sense of touch without actually looking at the strips.

Located beneath the rubber strips, and preferably secured thereto are cushion strips 8, preferably made of relatively soft sponge rubber. If desired, the cushion strips may be made even softer by cutting out portions thereof, as at 29. The said cushion strips are supported in U- shaped channels 3|, the upper edges of which serve to limit the downward movement of the playing strips. The said channels are supported at their ends in suitable recesses 32 in the end blocks 33, the intermediate recesses 34 being provided in said blocks to receive and guide the ends of the resistance bars 6.

The construction of the resistance bars is best illustrated in Figure 6. The said bars may be made of any suitable insulating material, but I prefer to use a relatively soft wood so that the windings of the resistance wire, when applied under tension, may be caused to embed themselves slightly at the edges of the bar so that they retain their positions. If the bar is made of wood, however, I find it advisable to laminate the bar as illustrated in Figures 6 and 7 to prevent warping.

The method of winding the bar is also illustrated in Figure 6, and it will be observed that there are groups of windings 35 spaced from and separated by other groups of windings 36. The individual windings of each group 35 are spaced and therefore insulated from one another, but the windings of groups 36 are in contact and uninsulated. The windings of groups 35 are of such nature, having regard to number of windings, resistance of wire, etc., that the resistance interposed between successive groups 35 are such as to provide a tempered scale when the playing strip is depressed by pressing the flnger against one of the frets. This is illustrated in Figure 11. In this connection, referring to Figure 2 it will be understood that the effective resistance interposed in the line is determined by the extreme left hand point of contact between the playing strip and the resistance bar. Thus, referring to Figure 11, and assuming finger pressure applied to fret 3a, there is contact between the playing strip and some of the windings 35a and there is contact with the windings 35a, but there is no contact with the windings 35b. Since, therefore, the extreme left hand point of contact is between the playing strip and the windings 36a, the pitch of the sound produced by the oscillator will be the previously determined tempered pitch for that specific group of windings. It will also be observed that if now, the performer rolls his finger rapidly to the left and right of the fret in the manner in which a violinist uses his finger to obtain a vibrato effect, the performer here may also obtain a vibrato effect, for in this case the extreme left hand point of contact shifts across the windings 36a, alternately to the

windings

35a and 35b, thus varying the resistance sufficiently for the purpose.

It will be noted in Figure 6 that the connecting windings 31 which join groups 35 with groups 36 are connected thereto at different points as indicated by the soldering points 38. This is done to enable exact pitches to be obtained in the groups 35, the efiective resistance, and hence the pitch, being determined by these connecting points. At the treble end of the scale it may be desirable to form the windings, of heavier wire, of low resistance, in order that the number of turns per group may be approximately the same throughout the scale.

The upper edge of the resistance bar is preferably rounded as shown, in order to provide good contact between the playing strip and the windings on the bar. A coating of insulation 40 may be applied to the sides of the bar to protect the windings from contact with the adjacent channels, but; the windings along the upper edge of the bar are uninsulated, of course.

As previously explained, the ends of the resistance bar are guided in recesses 34 in the end blocks 33, but the bar is yieldingly supported by leaf springs 42, 43 and 44. Each of the springs 142 and 44 is provided with an adjusting screw 45 by means of which the tension of the spring may be adjusted, and the spring 43 is provided with two adjusting screws 45 and 41 by which a double adjustment may be effected, one for the first part of the downward movement of the bar and the other for the latter part of such movement.

Immediately below each resistance bar is 10- cated a variable resistance element of any known type, that shown herein comprising a block having embedded therein alternate carbon and steel elements 52 contacted by a spring pressed bar 53 carrying an adjusting screw 54 in contact with the lower edge of the resistance bar. Downward movement of the resistance bar decreases the resistance imposed by element It, so that the greater the pressure applied by the performer's finger, the less the resistance and the greater the volume of tone produced.

In the drawings, certain stops 58 have been illustrated, Figures 1 and 3, projecting forwardly from the front panel. The said stops are intended to be used to controlthe quality or timbre of the tones produced by controlling a filter interposed between the oscillator and amplifier. In this manner the tones of many well-known instruments may be simulated, as for example,

violin, clarinet, saxophone, French horn, etc.,

' connections must However, since this mechanism is not claimed in this application, it will not be described herein.

It will be understood that the circuit diagram, Figure 2, shows only one oscillator 51 and only one playing strip, and that when additional playing strips are used, additional oscillators and also be used, all of the oscillators being connected to a single amplifier 58 and speaker 59, however.

For purposes of tuning, three variable resistances BI, 62 and 63 are provided, the resistance 8| serving to adjust the entire scale, while the resistance 62 may be used to'adjust the bass end of the scale and the resistance 63 may be used to adjust the treble end. In this manner very accurate tuning may be secured. If desired, a knob 64 may be mounted at any convenient part of the instrument, as illustrated, for example in Figure 1, said knob being connected to control the variable resistance 6!, so that the instrument may be quickly brought into time with other instruments or with It will be understood that the invention may be variously modified and embodied within the scope of the subjoined claims.

I claim as my invention:

1. In an electrical musical instrument in combination, a flexible contact strip of electricallyconductive material, a rigid bar wound with electrical resistance material, said bar extending substantially parallel to said strip and adapted to be contacted thereby at a multiplicity of different points to provide diflerent effective resistances, yielding means supporting said bar and adapted to any point along said contact strip, and a variable resistance located between the ends ofsaid bar and operated by said movements of said bar.

2. In an electrical musical instrument, in combination, a flexible contact strip of electrically conductive material, and cushion means extending parallel to said contact strip, said cushion an orchestra, for example.

means being adapted to support said flexible contact strip in normal position, and to yield to pressure applied to said contact strip by the fingers of the operator.

3. In an electrical musical instrument, in combination, a flexible contact stripof electrically conductive material, yielding cushion means extending parallel to said contact strip, and nonyielding means also extending parallel to said contact strip and adapted to limit the movement of said contact strip when pressed by the fingers of the operator.

4. In an electrical musical instrument, in combination, a flexible contact strip of electrically conductive material, cushion means extending parallel to said contact strip, said cushion means being adapted to support said flexible contact strip in normal position, and to yield to pressure applied to said contact strip by the fingers of the operator, and means connecting said contact strip to said cushion means.

5. In an electrical musical instrument, in combination, a flexible contact strip of electrically conductive materiaL'parallel cushion means extending parallel to said contact strip along the edges thereof, said cushion means being adapted to support said flexible contact strip in normal tions of said contact strips corresponding to the black keys 01' a piano.

BRUNO HEX-BERGER.