US2871745A - Keyboard operated electrical musical instrument - Google Patents

Description

2,871,745 KEYBOARD oPER'ATED ELECTRICAL MUSICAL INSTRUMENT Filed Dec. 2o, 1956 R. SCOTT Feb. 3, 1959 2 Sheets-Sheet 1 Feb. 3, 1959 l R. scor'r 2,871,745 y KEYBOARD OPERATED ELECTRICAL MUSICAL INSTRUMENT Filed Dec. 20, 1956 2 Sheets-Sheet 2 INVENTOR. MT

- @fu/fm United States Patent O KEYBOARD OPERATED ELECTRICAL MUSICAL INSTRUMENT Raymond Scott, Manhasset, N. Y.

Application December 20, 1956, Serial No. 629,505

15 Claims. (Cl. 84-1.25)

This invention relates to electronic musical instruments and more particularly to such an instrument operated by a keyboard of the piano type.

The invention provides a keyboard instrument of simple and reliable operation where a melody may be produced which smoothly and accurately slides in pitch from any note on the keyboard to any other note on the keyboard, whether higher or lower, without having to press any intervening notes. In general, the present musical instrument combines a tunable oscillator device of the type known asa Theremin, as disclosed in U. S. Patent No. 1,661,058, with a piano keyboard in such a way as to provide positive control of the pitch of the emitted note.

The Theremin is played by slight variations in capacitance produced by moving one hand of the operator toward and away from a control electrode. The other hand may be used for volume control. The Theremin, however, is extremely difficult to play. It is particularly difficult to obtain accurate pitch because extremely slight variations in the position of the hand of the operator will cause a particular note to sound off key. In fact, and although the Theremin has been known and greatly appreciated for more than 30 years, there are hardly more than about a half-dozen artists in the country who are capable of rendering satisfactory performances on the instrument.

With the foregoing in mind, the present invention provides a form of piano keyboard for pitch control of a Theremn instrument which is arranged to effect mechanical variations of predetermined magnitudes thus avoiding the inaccuracies of pitch which result when the instrument is played by body capacitance effects involving changes in the position of the hand of the artist. A particular advantage of my instrument is that each note is reached by smooth, sliding, predetermined ascents or descents, through predetermined increments of pitch, this action resulting in an extremely pleasing musical effect. Moreover, the gliding change from one note to another may be effected at varying rates at the will of the artist although the final pitch of the note is always true regardless of any particular technique or expression employed by the artist.

Adjustable means are further provided for individually mechanically tuning the particular note produced by each of the keys without affecting the over-all mechanical action of the instrument.

Additionally, means are provided for obtaining a con-v trollable vibrato effect which is electro-mechanical so as to simulate and derive the benefit of manual operation while obtaining the advantages of electrically controlled precision. The combination of a gliding change in pitch with the vibrato of this invention produces musical effects of an unusual tonal quality.

Various objects, features and advantages of the invention will become apparent upon reading the following specification together with the accompanying drawing forming a part hereof.

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Referring to the drawing:

Figure l is a schematic diagram illustrating an embodiment of the invention;

Figure 2 is an enlarged fragmentary sectional view in elevetion taken substantially along the line 2-2 of Figure Figure 3 is a fragmentary view similar to Figure 2 but illustrating the keyboard action;

Figure 4 is a view similar to Figure 3 but illustrating the tuning effect in mechanically shifting the keyboard members; and

Figure 5 is an enlarged fragmentary plan view illustrating a movable pitch control bar and guide means for the free end of the control bar.

Referring to Figure 1, there is shown an oscillator 10 of fixed frequency which may be 500 kilocycles, for example. There is also a tunable oscillator 11 which normally emits a frequency of 500 kilocycles, this frequency being reducible by increasing the capacitance between ground and a control terminal 12. The outputs of the oscillators 11 and 12 are connected to a heterodyne mixer 13. A filter 14 is connected to the output of the mixer 13 and passes frequencies in the audible range, up to 20 kilocycles, for example. The beat frequency between oscillators 1f)l and 11 which is produced in mixer 13, after passing through the filter l5 is applied to the input of an audio frequency amplifier 15. The output of the amplifier 15 is connected to a loudspeaker 16 which produces the audible note.

The amplifier l5 includes a gain control circuit illustratively indicated as a single line 17, the amplification of the amplifier 15 being varied by means of a foot pedal 18 connected to the gain control circuit 17. The pedal 18 may be arranged to operate a foot-controlled potentiometer (not shown), or may be otherwise connested to vary the amplification of the amplifier l5 in conventional manner. However, such means of amplification control is only representative of many suitable types. In fact, the well-known Theremin volume control is satisfactory, such control involving hand produced capacity changes which are used to control volume instead of pitch. I have determined that this action is not disadvantageous because precise control of volume is not critical while it certainly is so as regards pitch.

The frequency control terminal 12 of the oscillator 11 is connected as through an adjustable trimmer capacitor 20 to a stationary pitch control electrode 21 which is in the form of a flat plate insulated from ground and which is mounted on a supporting structure comprising a metal upright member 22 which for all practical purposes, is a part of the control electrode. The plate electrode 21 is secured to the upright 22 by a bolt comprising a wing nut 23 which serves to permit pivotal shifting of the position of electrode 21 for purposes of overall adjustment and tuning of the instrument.

The configuration of electrode 21 is not critical but, in the form shown, its lower edge 24 is inclined so that the electrode becomes gradually wider from bottom to top. This varies the capacitative reaction as will be shown hereinafter. In fact, edge 24 is shown to have two degrees of angularity or inclination, i. e., sections 24a and 24b, section 24b being fiatter so as to effect greater 'capacity changes at the upper range of the instrument.

The capacitance to ground of the stationary, plate electrode 21 is varied by means of a movable control bar 25 which carries a grounded electrode 26. Preferably, the control bar 25 is formed of light material such as balsa wood. The grounded electrode 26 may be formed of aluminum foil vsecured to the bar although substantially any form of metal member such as a rod may be employed. The control bar 25 is of cantilever construction, being pivoted at 27, the pivot 27 being shown connected to ground. A conductor 28 connects the grounded pivot 27 to the grounded electrode 26.

The control bar 25 is arranged so that it may selectively move through predetermined angular displacements in a clockwise direction by means of the keys of a piano type keyboard designated generally as 30. Only a single octave is shown in the drawing although the finished instrument will of course comprise a greater range.

The piano keys for progressively higher notes are located progressively nearer to the pivot 27 so that the depression of a key corresponding to a high note produces a greater clockwise displacement of the control bar 25 than the depression of a key for a low note.

It will be seen from Figure 1 that the configuration of the control electrode 21 provides a greater etective area in proximity to the grounded electrode 26 when the control bar 25 is swung through a large angular displacement than when it is swung through a small angular displacement. This is because it is wider at its upper portion'than at its lower portion. As the capacitance to ground of the control electrode 21 is increased, the frequency of oscillator 11 is correspondingly decreased. As a result, the beat frequency or difference frequency between the frequencies of the fixed frequency oscillator and the variable frequency oscillator 11 increases and the note emitted by the loudspeaker 16 rises in pitch. This variation in capacitance to ground s extremely small. It is estimated that it need be only of the order of less than 10 micromicrofarads in order to cover the entire audible range of pitch. As in the conventional manually played 'l`heremin, the frequency varies continuously in changing from note to note and the note is sustained at the same intensity during changes in pitch except insofar as its volume may be varied by the artist.

In Figure 2 isjillustrated means by which the angular displacement of the control bar 25 which is produced by the depression of each key may be individually adjusted for each key so that each key will produce a note of correct pitch when it is fully depressed. This is accomplished by the interaction of the keys and a series of individual fingers as will hereinafter be described.

The keys themselves are substantially conventional, each key comprising an elongated bar 31 which is pivoted inbar 31 longitudinally fixedly positioned. The pin 32 t is mounted on a fixed supporting member 34 and a felt washer 35 underlies the key bar 31 to prevent noise.

A series of felt lcovered fingers 36 is arranged with eachl finger in engagement with the free end of one of the key bars 31. Each finger 36 is connected to a horizontally adjustable mounting block 37 by a pivot pin 38. The pivotal axis provided by the pivot pin 38 is spaced from and parallel to the pivotal axis of the key bar 31 which is provided by the upright pin 32. Near its pivoted end, the finger 36 is provided with an upright portion 39 which is arranged to engage the mounting block 37 and act as a stop for limiting clockwise movement of the finger 36. The free end portions of all of the fingers 36 are aligned in a common horizontal plane for reasons which will be explained hereinafter.

The pivotal movement of each key bar 31 is limited in conventional manner as in a standard piano keyboard. Accordingly, when a key is pressed to the limit of its travel, it free end 40 rises to a predetermined height and elevates the pivotally mounted finger 36. This in turn swings the control bar 25 upwardly as illustrated in Figure 3 and in broken lines in Figure l.

This invention also includes a simple and effective individual tuning system which does not interfere with the normal operation of the instrument as will be shown slot 41 through which a screw passes and secures the block 37 to a fixed supporting member 43.

When the screw 42 is loosened, the supporting block 37 may move axially in thelongitudinal direction of the key bar 31 so that the free end 36a of linger 36 is moved nearer to or farther away from the free end 40 of the key bar 31. If the free end 36a is moved rearwardly so that it is closer to the free end 40 of the key bar 31, then the amount of angular displacement of the felt covered finger 36 will be decreased when the key bar 31 pivots to its limit of travel by depressing the key portion of the key bar 31. When the free end 36a is moved forwardly or to a more overlapping position on the free end 40, the amou'nt of angular displacement of the felt covered linger 36 will be increased for the same upward movement of the free end 40. In other words, the free end 40 produces greatest angular displacement of the finger 36 when it is closest the pivot point 38 and it produces least displacement when it is closest the free end 36a. This is clearly illustrated in Figure 4 where the finger 36 is far less angularly displaced and the'control bar lifted less because the free ends of the finger and key bar respectively are closer. The amount of angular displacement of the free end 36a of the felt covered linger 36 may thus be adjusted by varying the position of the pivot pin 38 relativeV to the free end 40 of its associated key bar 31. The desired adjustment may be retained by tightening the screw 42.

since the greater such displacement, the greater the lift imparted to the control bar 25. The elevation of control bar 25 determines the pitch. Thus, the simple longitudinal adjustment of each linger 36 can be employed to effect individual tuning of the keys.

A particular advantage is derived by the above described' tuning method in that the normal relationship of the free end 36a with the underside of the control bar remains completely unaffected and all the free ends 36a Will remain in the same horizontal plane. Accordingly, the normal position of control bar 25 will be as shown m Figure l where it is resting liatly on all the fingers 36. It will be recognized that if the fingers 36 were at varying levels, the bar 25 would rest on the highest one and the others would have to rise before engaging the bar. Such lost motion would disturb proper operation of the instrument since the musician would not know how far to depress each key to sound the note. This is avoided by having all the lingers in horizontal alignment notwithstanding their tuning function.

In order to return finger 36 to a normally downward, horizontal position, the spring 44 extends between block 37 and finger 36. It is stressed when the finger 36 is elevated so that it tends to restore the finger to normal position.

inasmuch as the spacing between the grounded electrode 26 and the stationary control electrode 21 must be carefully maintained, the free end of the control bar 25 is guided between theA upright 22 and another upright 45. Headed pins 46 are carried by the lfree end of the control bar 25 and engage the confrontingI faces of the spaced uprights 22 and 45, the pins 46 being disposed at opposite sides of the control bar 25. The heads of the pins 46 serve to reduce friction. However, I have produced an embodiment which eliminates one of the pins 46 and its corresponding support 45. This has been done by making the control bar so light that it oats gracefully on its pivot 27 and does not tend to quiver. Thus, a control bar of balsa wood was made 27 inches long and it weighed about 1l grams. This bar was guided only by one support.

The desirability of the instrument has been increased greatly by adding a vibrato or tremolo which is unusually effective. This isaccomplished by simulating hand operation rather than by simply employing conventional electronic tremolos. I have discovered that tremolo is best produced by vibrating a condenser plate in proximity to a control electrode. This effectively reproduces conventional Theremin action but with precision, selectivity and eect that was not possible to achieve by the human hand. l

As shown in Figure 1, a vibrato effect is provided by varying the capacitance to ground of'an auxiliary control electrode 50 which isconnected to terminal 12 of oscillator 11 through the trimmer capacitor 20 along with the main control electrode 21. The auxiliary electrode 50 cooperates with a movable grounded electrode. The

grounded electrode 51 is mounted at the free end of a grounded electromagnet armature 52. A spring 53 urges the armature 52 to a ixed predetermined position from which it may be displaced by energizing the operating winding 54.0f an electromagnet 55. The operating winding 54 of electromagnet 55 is connected to the output terminals 56 of a low frequency vibrato or tremolo oscilof the output voltage at the output terminals 56 of oscillator 57 bmay be varied by means of a foot pedal 60 connected to the output control circuit 58. Another foot pedal 61 which is connected to the frequency control circuit 59 is used to vary the output frequency of the oscillator 57 from its minimum to its maximum output frequency.

By means of the foot pedals 60 and 61, mechanical oscillations of controllable frequency and amplitude may be imparted to the movable grounded electrode 51 and these oscillations will produce slight variations in the pitch of any note being played. This rhythmic variation in pitch gives the desired vibrato eiect.

Briefly, the operation of th'e instrument is essentially as follows:

The musician will depress selected keys successively to produce a tune. During such rendition, the control bar 25 will rise and fall depending on whether the notes are high or low. The high notes will produce a greater rise.

The successive notes will glide easily and pleasantly from one to another. Each no te will rise or fall to the next one, resulting in a smooth and flowing rendition.

It will be observed that the rectilinear edge section 24b serves the higher notes of the range. The slope thereof is less steep than that of edge section 24a so that for like changes in the elevation of bar 25, more capacity change is realized. The greater capacity effects at the high frequencies may be further enhanced by thickening the upper end of plate 21 or bending it inwardly, these expedients simply bringing the plate 21 closer to the control bar electrode 26 and thus increasing capacity.

Volume will be controlled either by pedal 1B or by Theremin type volume control as explained above.

The tremolo is most important to maximum effectiveness. This may either be pre-set, or controlled during the rendition by operating pedal 61 while the amplitude thereof may be controlled by pedal 60.

While an electrostatic type of variable reactance frequency control device has been specifically vdisclosed for varying the frequency of oscillation of the oscillator, it is to be understood that other types of conventional variable reactance means may be substituted for controlling the pitch of the emitted note, said variable reactance means being provided with a mechanically displaceable keyboard-controlled movable element for determining the frequency of oscillation as disclosed herein. Regardless of the type 'of frequency control device which may be employed, the frequency of oscillation will vary continuously during keyboard-controlled movement of the displaceable member from one position to another as when different keys are operated in sequence.

It will be apparent to those skilled in the art that changes and modifications may be made in the specific embodiments of the invention which have been herein shown and described without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A musical instrument comprising loudspeaker means for emitting an audible note, an oscillator of controllable frequency connected to energize said loudspeaker means for producing said note, said oscillator comprising a terminal for controlling the frequency of oscillation of said oscillator by variation of the capacitance to ground of said terminal, a fixed control electrode connected to said terminal, a movable grounded electrode cooperating with said control electrode for varying the pitch of said note by changes in the relative positions of said electrodes, a control bar by which said grounded electrode is carried, an end portion of said control bar being pivoted to supporting means for angular movement of said control bar, a keyboard comprising series of parallel elongated key bar members extending perpendicularly with respect to said control bar, and means'individually interconnecting each of said key bar members and said control bar whereby those key bar members which are located nearer to said pivoted end portion of said control bar will produce greater angular displacements of said control bar than those of said key bar members which are more remote from said pivoted end portion.

2. A musical instrument according to claim l in which each of said key bar members is pivoted intermediate its ends and comprises a manually depressable key portion at one end and a free portion at itsother end, and wherein said means interconnecting each key bar member with said control bar comprises a finger member interposed between said free end portion of each key bar member and said control bar.

v 3. A musical instrument according .to claim 2 wherein each of said finger members is pivotally connected to supporting means, said pivotal connection including means for adjusting the distance between said pivotal connection and said free end portion of its associated key bar member.

`4. A musical instrument according to claim l further comprising an auxiliary electrode connected to said terminal for producing changes in the frequency of oscillation of said oscillator independently of said control bar, a source of low frequency oscillations of controllable frequency and amplitude, an electromagnet connected for energization from said source of low frequency oscillations, a spring biased armature included in said electromagnet, said armature being displaceable in accordance with the frequency and amplitude of oscillation of said low frequency source, and a grounded electrode carried by said armature and cooperating with said auxiliary electrode for producing a tremolo effect.

5. A musical instrument according to claim l in which said control bar extends generally horizontally when none of said key bar members is operated, said grounded electrode extending along portions of said control bar which are spaced from said pivoted end portion thereof, said control electrode having an upperportion of increased area which cooperates with said grounded electrode in response to increased angular displacements of said control bar from said horizontal position.

6. A musical instrument according to claim 5 in which said upper portion of said control electrode is defined by a generally rectilinear edge which is less steeply inclined than the corresponding edge of the lower portion of said control electrode.

7. A musical instrument of the class described, comprising an oscillator of controllable frequency, means connected to said oscillator for producing an audible note having a pitch determined by the frequency of oscillation of said oscillator, means connected to said oscillator and including an an ularly movable control bar for varying the frequency ci oscillation of said oscillator in accordance with the position of said control bar, a keyboard comprising a series of key bar members, all of said key bar members having free end portions aligned along said control bar in spaced relationship with respect thereto, and a series of pivotally mounted finger members each associated with one of said key bar members and interposed between said free end portion of its associated key bar'member and said control bar, all of said finger members having free end portions which are aligned substantially in a common plane when none of said key bar members is operated, operation of any one of said key bar members causing one of said finger members to move said control bar to a predetermined position for causing said oscillator to oscillate at a frequency corresponding to the pitch of the note associated with the particular key bar which is operated.

8. A musical instrument as in claim 7 wherein said control bar is substantially horizontal when none of said key bar members is operated and in which said plane in which said free'end portions of said finger members are aligned is a horizontal plane.

9. A musical instrument according to claim 8, in which the bottom surface of thefree end portion of each finger member touches the free end portion of one of said key bar members, said control bar resting on the top surfaces of all of said free end portions of said finger members when none of said key bar members is operated.

10. A musical instrument according to claim 9 further comprising a return spring acting on each of said finger members for yieldingly urging it into its position of alignment in said horizontal plane.

11. A musical instrument of the class described, comprising loudspeaker means for producing an audible tone, an oscillator of controllable frequency connected to energize said loudspeaker means for generating said tone, electrostatic means connected to said oscillator for controlling the frequency of oscillation thereof, said electrostatic means including a physically movable electrode, a keyboard comprising a series of individually movable keys, a movable control member by which said movable electrode is carried, means operatively associated with each key and engageable with said control member upon operation of said associated key tor imparting a predetermined displacement to said control member in response to said operation of said key to cause said oscillator to oscillate at a predetermined frequency for generating a tone of predetermined pitch, and auxiliary electrostatic means connected to said oscillator for producing supplemental variations in the frequency of oscillation thereof independently of said keyboard, said auxiliary electrostatic means including a further physically movable electrode, electromagnetic means for displacing said further movable electrode, and a source of low frequency, vibrato oscillations of controllable frequency and amplitude connected to energize said electromagnetic means for producing a tremolo effect.

l2. A musical instrument of the class described, comprising loudspeaker means for producing an audible tone. an oscillator of controllable frequency connected to energize said loudspeaker means for generating said tone, electrostatic means connected to said oscillator for controlling the frequency of oscillation thereof, said electrostatic means including a physically movable electrode, a keyboard comprising a series of'individually movable keys, a movable control member by which said movable electrode is carried, means operatively associated with each key and engageable with said control member upon operation of said associated key for imparting a predetermined displacement to said control member in response to said operation of said key to cause said oscillator to oscillate at 'a predetermined frequency for generating a tone of predetermined pitch, and said electrostatic means comprising a further electrode in addition to said physically movable electrode, operation of any of said keys producing relative movement between said movable electrode and said further electrode, said electrodes being shaped to provide a greater change in capacitance therebetween for a predetermined amount of relative movement therebetween for displacements corresponding to the higher notes of the frequency range of said instrument than for the lower notes thereof.

13. A musical instrument of the class described, comprising an oscillator of controllable frequency and adapted to have a loudspeaker connected thereto to produce an audible note, said oscillator comprising a terminal for controlling the frequency of oscillation of said oscillator, a fixed control electrode connected to said terminal, a movable electrode cooperating with said control electrode for varying the pitch of said note by changes in the relative physical positions of said electrodes, a control bar by which said movable electrode is carried, a keyboard comprising a series of parallel, elongated key bar members extending perpendicularly with respect to said control bar, a series of finger members each associated with one of said key bar members, all of said finger members having free end portions which are aligned substantially in a common horizontal plane when none of said key bar members is operated, said control bar normally resting on all of said free end portions when none of said key bar members is operated, operation of any one of said key bar members causing one of said finger members to move said control bar to a predetermined position for causing said oscillator to oscillator at a frequency corresponding to the pitch of the note associated with the particular key bar which is operated.

14. A musical instrument according to claim 13 and I wherein said control bar is pivoted at one end thereof and is angularly movable about said pivot by said finger members, the finger members closer to said pivot' producing a greater angular movement of said control bar than the finger members further away from said pivot.

l5. A musical instrument according to claim 14 and wherein said key bar members have a free end which actuate the underside of said free end of said linger members, said finger members being adjustable along the longitudinal axis of said key bar members so as to vary the point at which said free end of said key bar members contact said free end of said finger members, said finger members being pivoted at their ends oppositeto their i free ends thereof whereby the extent of actuation of said finger members by lsaid key bar members is controlled by said adjustment.

References Cited in the file of this patent UNITED STATES PATENTS 2,193,060 Davis Mar. 12, 1940 2,308,051 Cahill Ian. 12, 1943 2,3 14,496 Hammond Mar. 23, 1943 2,328,282 Kock Aug. 3l, 1943

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