US1929030A - Apparatus for the production of music - Google Patents

Description

B. F. Mxr-:ssNER 1,929,030

APPARATUS FOR THE PRODUCTION OF MUSIL Oct. 3, 1933.

Original Filed Avril 18, 1932 A// hl ANP.

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/2 frn/rams 50 A TTORNEY.

Patented Oct. l 3, 1933 1,929,030 APPARATUS Foa THE rnoDUc'rroN oF Music Benjamin F. Miessner, Millburn Township, Essex County, N. J., assignor to Miessner Inventions, Inc., a. corporation of New Jersey Application April 1s, 1932, serial No. 605,961

I Renewed July 8, 1933 15 Claims.

This invention relates -to the production of music from a plurality of tuned vibrators; and

more particularly to instruments wherein the vibration of the vibrators may be translated into 5 sound by mechanico-electro-acoustic translation,

as broadly disclosed and claimed in my co-pending applications, Serial Number 512,399, filed January 30, 1931, and Serial Number 573,319, fued November 6, 1931.

1oy It is an object of my invention to provide an instrument of the class described in which the translation of vibrator vibration into sound may be selectively effected either by mechanicoelectro-acoustic translation or by direct mechanico-acoustic translation, such as employed for 25 strument of the piano type employing mechanicoelectro-acoustic translation; of particular means for coupling and decoupling the strings to andfrom a resonator; and of improved means of securing the strings to the bridge.

, 3G lA general object is the provision of an improved instrment of the class describedi Other and allied objects will morev fully appear from the following description and the appended claims.

.f In the detailed description of my invention,

hereinafter set forth, reference is had to the accompanying drawing, of which:-

Figure 1 is a plan view of a portion of an instrument embodying my invention;

, Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1, in which certain further mechanical, and schematically-shown electrical, -components appear;

Figure 3 is a fractional cross-sectional view 45 similar to a portion of Figure 2 and illustrating a modification thereof; K

Figure 4 is an enlarged, fractional, crosssectional view of which the right-hand portion is taken along the line 4 4 and the left-hand portion along vthe line 4'-4' of Figure 1; and

Figure 5,is an enlarged plan view illustrating the detail of the arrangement I have employed for securing the strings to the bridge of the instrument shown in Figure 1. In Figure 1, I show aplan view of a portion of an instrument of the piano type, and in Figure 2 a cross-sectional view thereof taken along linefs2-2 of Figure 1. For the sake of clarity strings, bridgeand hitch-pins, the acoustic insulating member 34 of Figure 2, and the sound- 30 board-like member 10 (of Figure 2) and its reinforcements, have been omitted from Figure 1; and from both these figures have been omitted such conventional elements as frame or plate reinforcing bars, which it will be understood may be employed as customarily. A, In these figures may be seen a rim 1, a rim cross-member 2, and a plurality of rim-beams 3 angularly disposed between cross-member 2 and rim 1. All of these parts may be of the con- `70 ventional type and arrangement, except that rim land cross-member 2 may extend downwardly below the level of the bottom of rim-beams 3. Spaced above rim-beams 3, and secured to rim 1 and cross-member 2may be a plurality of 75 ribs 4, for example of the type usually employedl for reinforcement of the soundboard of the conventional piano, preferably arched toward the strings; but no soundboard or 'other resonator is immediately associated therewith. Secured thereto may be the conventional main or treble bridge 5 and bass bridge 6, over which bridges the strings 7 are strung to hitch pins 8 in frame or plate 9, which may be of the usual construction. .An improved arrangement for securing the strings to the bridge is shown and hereinafter described; but it will be understood that the strings may be secured to the bridge in the usual manner if desired. The usual hammers 19, dampers 20 and hammer action may of course 9 0 be provided for effecting and controlling string vibration-i. e., for playing the instrument.

Underneath the rim-beams 3 may be provided a 'soundboard-like member or diaphragm 10. While this diaphragm may be in general similar to the conventional soundboard, it is preferably thinner and need not be arched toward the strings. It may be reinforced by a plurality `of ribs 11, but such reinforcement is preferably materially less than that of the usual soundboard, ribs 11 to that end being smaller and more flexible than conventional ribs, such as 4. Secured to the diaphragm at each of a plurality of points preferably under bridge' 5 is seen a coupling rod 12, aiTlxed to the top of which is an armature 13. The coupling rods 12 may if desired pass through clearance holes 14 in rim-beams 3. Immediately above each armature 13', and secured to the bottom of bridge 5, is provided an electromagnet 15. While only one electromagnet 15 is shown in 110 the armature from the poles of the electromagnets to prevent intermittent contact when bridge 5 vibrates upon playing of the instrument. To facilitate adjustment the bottom ends of the coupling rods 12 may be provided with a screwdriver slot 21, the/bottom portions of the rods threaded, and their connection to diaphragm 10 made by screwing into threaded flanges 22 afiixed to the top of the diaphragm, and to the bottom either of the diaphragm or preferably of one of the ribs 11 affixed thereto. By turning of a rod 12 its vertical position, and hence that of the afxed armature 13, may thus be adjusted.

When the electromagnets 15 are energized, upon closing of switch 18, the armatures will be attracted thereto; and nal adjustment of the vertical position of the armatures is best made under these conditions, care being taken that each armature make intimate contact with both poles of the associated electromagnet.

It will be seen that upon the energization of the electromagnets 15 both the bridge 5 and the diaphragm will be moved, each toward the other. The bridge 5 is relative immobile, however, because of the resistance to downward motion provided by the arched rib structure 4, which is already sustaining a great downward pressure caused by the bearing or" the strings 7 on the bridge. On the other hand the diaphragm and its reinforcement, being made relatively flexible, is quite mobile. position of bridge 5 and diaphragm 1G upon energization of the electromagnets will be made up almost entirely of motion of the latter and negligibly of motion of the former; tuning of the strings is therefore inappreciably affected.

Thus when the electromagnets are energized, the bridge 5 is connected to the diaphragm, which then acts as a resonator, vibrating in accordance with the vibration of the bridge, as does the soundboard in a conventional piano. This is of course true for the bass bridge 6, as well as for the main bridge 5, since the latter necessarily vibrates with the former because of the support of both by ribs 4. Thus direct mechanico-acous- .tic translation of string vibration is eected.

If desired a strip 35, of the same contour as and located directly under bridge 5, may be secured to the top of the diaphragm, providing a mild reinforcement thereof in the direction of the bridge. A fragmentary cross-sectional illustration thereof appears as Figure 3, which is alternative to the similar portion of Figure 2. In Figure 3 the upper threaded ange 22 has been omitted, the coupling rod being shown threaded into the strip 35.

When the electromagnets are de-energized, as is the case with switch 13 open, the diaphragm is disconnected from the bridge 5 and is consequently unaffected by string vibration, ceasing tobe a resonator. Under this latter condition the vibration of the strings may be translated into sound by mechanico-electro-acoustic translation in accordance with the principles disclosed in the' co-pending applications above referred to. Thus adjacent each string, preferably at a constant, small fractional part of ,its length Hence the combined change of reaaoeo from the rear end thereof, may be provided a stationary insulating member 23 having a conductive surface 24 nearest the strings. The mem ber 23 may be mounted to the plate or frame 9 in any convenient manner; and the conductive surface 24 is spaced away from each string in general sufficiently to avoid contact therewith under conditions of maximum Vibration of the latter.

Conductive surface 24 may be electrically connected to the grid of a thermionic vacuum tube 25, whose iilament may be energized as by battery 26 and whose anode current may be supplied as from a tap on high voltage battery or other source 27. The filament of tube 25 may be established at a potential higher than that of the negative terminal of battery or source 27 by the flow of anode current through condensively bypassed resistance 28; and the grid of tube 25 may be biased to the potential of such negative terminal by high resistance 29. Thestrings may be established at a D. C. potential different from that of conductive surface 24 by connection of the plate 9 (with which the strings make Contact) to the positive terminal of battery or source 27. In the Output circuit of tube 25 may be provided amplifier 30, and following the latter may be volume control 31, further amplifier 32,. and loudspeaker 33.

.lt will be appreciated that between each string 7 and the conductive surface 24 a small electrostatic capacityexists, and that these capacities in parallel with each other form a total capacity between strings 'and conductive surface. This capacity is charged from battery or source 27 through resistance 29, and this charge cannot change rapidly because of the high value of the latter resistance. If now any string 7 be vibrated Jin'a vertical plane, as by striking by its hammer i9, the capacity between it and the conductive surface 24 will be varied oscillator-ily in accordance with the frequency and waveform of the point of the string opposite the conductive surface. The total capacity between the strings and the surface will be likewise varied, though in reduced degree; and by virtue of the relatively constant charge in this capacity the voltage across it will likewise vary. The oscillatory variations in this voltage will be seen to be applied to the grid of tube 25; by this tube and succeeding amplier 30 they are amplified; they may be controlled in respect of amplitude and further ampliied if desired by volume control 3l and further amplifier 32, respectively; and nally they may be translated into sound by loudspeaker 33. Thus a mechanico-electro-acoustic chain of translation is provided which may be employed in a degree fully regulated by volume control 31; this translation may thus be eifected alternatively to or coincidentally with the mechanico-acoustic translation effected by member 10 upon energization of the electromagnets 15.

It is desirable that the tube 25, the conductive Vsurface 23, and parts immediately associated therewith be protected from stray electrostatic elds. To this end there may be provided about tube 25 and its immediate circuits electrostatic shielding 36. Similar shielding may be disposed about the interior of the instrument proper; but I have found it very convenient to create an electrostatic shield by painting the inside of the rim 1, member 2 and lid 37 with one or more coats of a colloidal, conductive solution-such for example as the graphite preparation sold under the trade name of Aquadag. The thus painted dynamic type.

Vsectional view of which the right-hand portionis 1,929,oso 3 surfaces have been indicated in Figure 2 by heavy lines, and the symbol'38 used to designate the coats of such paint; Electrical contact should be made between the shielding and a member having the potential of the plate 9; this is accomplished for rim 1 and cross-member 2 (which are contiguous as seen in Figure l) by the resting of a portion 39 vof the frame on a painted ledge on the inside of rim 1. The painted surface of the lid 37 may in turn make electrical contact with the painted portion of rim 1 through the hinges customarily provided between lid and rim. To complete the shielding a wire screen 40 may be aixed to the bottom of rim-beams 3, its edges making contact with the painted surfaces of rim 1 and cross-member 2.

For use with mechanico-electro-acoustic translation, when this is to be employed alone or alternatively to mechanico-acoustic translation as' above described, I show an arrangement wherein diaphragm 10 is employed as part of a 'loudspeaker system. This arrangement may be found advantageous both in that it provides an efficient loudspeaker and in that it results in a similar sound source location for each type of translation. Thus in Figure 1, I have indicated the contour and typical location of two diaphragm-driving translating units 41 of the well-known electro- In Figure 4, a fractional crosstaken along line 4 4 and the left-hand portion along the line 4*--4 of Figure l, I show the details of these units'.

Thus in Figure 4 the shell or outer core of each unit 4l may be represented by 42, the central pole by 43, and the face plate by 44, the latter forming annular gap 45 with central 'pole 43.

.The shell 42, to which the other parts may be assembled, may be fastened to the side of rimbeam 3, and may protrude through an opening provided therefor in screening 40. Freely positioned in the gap 45" and securedgto diaphragm lo may be provided thin' cylinder 47 carrying voice-coil 48. A iield coil 46 .may be provided vabout central pole 43, such coils being shown .schematically in Figure 4. d battery or other direct current source 49 may be provided for energizing the field coils 46 ci both the units 4l. 'The voice coils 48 ci the two units 4l may be connected in series or parallel with each other and to the secondary of transformer 50, which is provided with primary terminals 5l.

. Reference being had to Figure, 2, 'there will be seen switch 52, by which the outputoi amplier 32 lmay be disconnected from schematicallyshown loudspeaker 33 and connected to terminals 5L If this is done, there will be supplied to the voice coils 48 the amplified oscillations rst translated from `string vibration. By virtue ci the placement of these coils in the gap 45 and of the high flux therein maintained by energized iield coils 46, the oscillations will be translated into vertical motion of voice coils 4S and hence oi the diaphragm 10, to which they are secured.

The diaphragm, now a part of the loudspeaker system, will be seen to be relatively near the strings '7; and it is necessary to provide acoustic insulation between it and ,the strings to prevent acoustic feed-back. Accordingly I have shown in Figure 2 a sheet 34 of wood, or preferably of a vibrationallyA dead, composition material, disposed above the rim beams 3; and between it and the screening 40 carried by the bottom of the rim beams may be stuffed soft, sounding-absorbing material 57, such as felt, whichis indicated in Figures 1 and 4.

While I have shown two translating units 41" driving the diaphragm, it will be understood that one only may be employed if desired. A plurality, with eldand voice-coils respectively poled to aid each other at each instant, is desirable, however, because of the relatively large area of the diaphragm 4to be vibrated thereby.

In Figure 5, I show a top View of the bridge 5 as engaged by two springs 7. It has been shown in the United States Patent No. 1,915,859, issued June 27, 1933, to myself and Charles T. Jacobs, that it is of great convenience in ne adjustment of the distances of the strings from the translating system (in this case conductive surface 23) to pass each string in a groove 55 in a screw such as 53, and thence around a simple pin such as 54, both screw and pin being mounted in the bridge. Fine distance adjustment is then readily effected by rotation of the screw. I have discovered that two strings may be passed in the same groove on respectively opposite sides of the screw 53, the strings then crossed and. passed on respectively opposite sides of pin 54. This provides simultaneous distance adjustment of two strings, and is particularly convenient when two strings are employed for each note of the instrument, or of its treble, as may be done in the instrument herein described. z

It will be appreciated that various modifications oi the structures and combinations of apparatus hereinabove disclosed may be made without departing from the spirit or scope of my invention as in the appended claims dened. Thus the mechanical means (rods l2) coupling the bridge (and through the latter the vibrators) to the resonator l0 may be selectively brought into and out of action in other ways than by the particularly illustrated electromagnetic control; other forms oi mechanicc-electric translating devices may be substituted for the electrostatic form shown; the switch 18 controlling the energization of the electro-magnets may be tandenied with a switch such as 56 controlling the electrical amplifying system, one being opened when the other is closed for unicontrolled selective alternation oi translating systems, etc.

I claimz'- l. In a musical instrument, the combination or" a plurality of tuned vibrators; means for vibrating said vibratorsj a diaphragm; mechanical means for coupling said diaphragm with said vibrators; and selectively operable means associated with said coupling means for controlling the operation thereof.

2. In a musical instrument, the combination of a plurality of tuned vibrators; means for vibrating said vibrators; a vibratile system coupled to all of said vibrators; a diaphragm; mechanical means for coupling said diaphragm with said vibratile system; and selectively operable means associated with said coupling means for controlling the operation thereof.

3. In a musical instrument, the combination of a plurality of tuned vibrators; means for .vibrating said vibrators; a mechanico-electrointo sound; a diaphragm; a mechanical system for coupling said diaphragm with said vibrators;

and means included in said mechanico-electroof a plurality or' tunedvibrators; means for vibrating said vibrators; a vibratile system coupled to all of said vibrators; a mechanico-electroacoustic system for translating the vibrations ci said vibrators into electric oscillations and thence into sound; a diaphragm; a mechanical system for coupling said diaphragm with said vibratile system; and means included in said mechanicoelectro-acoustic and said coupling systems for controlling their respective operations.

5. ln a musical instrument, the combination ci a plurality of tuned vibrators; means for vibrating said vibrators; a mechanico-electric system for translating the vibrations of said vibrators into electric oscillations; a diaphragm; a mechanical system for coupling said diaphragm with said vibrators; means for translating said oscillations into vibrations of said diaphragm; and means included in said mechanico-electric and said coupling systems for controlling their respective operations.

6. In a musical instrument, the combination of a plurality of tuned vibrators; means for vibrating said vibrators; a diaphragm disposed near said vibrators; mechanico-electric translating apparatus for translating the vibrations of said vibrators into electric oscillations; means for vibrating said diaphragm in accordance with said electric oscillations; and acoustic shielding disposed between said diaphragm and said vibrators.

7. lin a piano, the combination of a plurality of tuned strings; means for vibrating said strings;

a vibratile system engaging said strings and comprising at least one bridge and vibratile supporting means therefor; a diaphragm; a mechanical coupling system interposed between said vibratile system and said diaphragm; and electromagnetic means included in said coupling system for controlling the operation thereof.

8. Ina piano, the combination of a plurality o tuned strings; means for vibrating said strings; a vibratile system engaging said strings and comprising at least one bridge and vibratile supporting means therefor; a diaphragm; and selective means for effecting coupling between said vibratile system as one member and said diaphragm as the other, said means comprising at least one electromagnet secured to one of said members, at least one armature secured to the other o said members, and means operable to energize said electromagnets.

9. In a piano including rigid portions, a plurality of tuned strings and means for vibrating said strings, the combination ofv mechanico-elec-- tric 'translating apparatus for translating into electric oscillations the vibrations of said strings; a diaphragm peripherally secured to said rigid portions; electro-mechanical translating apparatus operatively connected to said diaphragm to vibrate the same; and means for supplying said electric oscillations to said electro-mechanical translating apparatus.

1G. In a piano including rigidyportions, including a plurality o tuned strings and including means for vibrating said strings, the combination of mechanico-electric translating apparatus for translating into electric oscillations the Vibrations of said strings; a diaphragm peripherally secured to said rigid portions electro-mechanical translating means operatively connected to said diaphragm to vibrate the same; and means for supplying said electric oscillations to said electromechanical translating means.

l. En a piano including rigid portions, including a plurality of tuned strings and including means for vibrating said strings,vthe combination of mechanico-electric translating apparatus for translating into electric oscillations the vibrations o said strings; a diaphragm peripherally secured to said rigid portions; at least one electro-dynamic oscillation-vibration translating unit, the moving coil of each said unit being connected to a respectively diierent portion of said diaphragm; and means for supplying' said electric oscillations to said translating units.

l2. in a musical instrument, the combination of two tuned strings; a member supporting said M strings; a screw rotatable in said member; a circumferential groove in said screw; and a pin in said member near said screw, said two strings resting in said groove on opposite sides of said,

screw,V crossing each other between said screw and said pin, and resting against respectively opposite sides of said pin.

1 3. in a musical instrument of the type including acase and therein a plurality of vibrators and mecnanico-electric translating apparatus for translating the vibrations of said vibrators into electric oscillations, an electrostatic shield for at least a portion of said translating apparatus, comprising one or more coats of conductive paint applied to surfaces of said case and an electrically conductive path from said surfaces to a point in said translating apparatus.`

14. In a musical instrument of the type including a case and therein a plurality of vibrators and mechanico-electric translating apparatus for translating the vibrations of said vibrators into electric oscillations, an electrostatic shield for at least a portion of said translating apparatus, including one or more coats of conductive paint applied to surfaces of said case and an electrically conductive path between said surfaces and said vibrators. i

l5. l'n a musical instrument, the combination of a mechanical oscillator; means for producing vibrations thereof, whereby there is produced therein a vibrating force; means for translating said vibrations into electric oscillations and said oscillations into a second vibrating force; a diaphragm; and means selective with respect to said two forces and interposed between said oscillator and said diaphragm for subjecting said diaphragm to said forces. y

` BENJANUN l?. MIESSNER.

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