US1884578A - Electrical sostenuto piano - Google Patents

Description

Oct. 25, 1932. s. COOFER I ELECTRIGAL SOSTENUTO PIANO Filed'March 25, 1927 2 Sheets-Sheet' l 001:. 25, 1932. s COOPER 1,884,578

ELECTRICAL S 05 TENUTO PIANO Filed March 25. 1927 2 Sheets-Sheet 2 Patented Oct. 25, 1932 UNITED STATES SIMON COOPER, 01? BROOKLYN, NEW YORK ELECTRICAL SOSTENUTO PIANO Application filed March 25, 1927. Serial No. 178,208.

'Ihs nventon relates to electrcal sostenuto panos of the type wherein a pulsator is provided for current fiuctuation in such accord wth the movement of the piano stfing during the Vibrtton of the latter, that a magnet in crcuit wth sad pulsator s operated tosustain the vibration of the string by magnetic pluck relative to the string during each vbmtory movement of the string toward the magneti. 7

the jnvention is to provide a pulsator end mounting meu1s for the latter, as Well a1so as a method of operatng such pulsator, adapted to nsure such ntiation of the mag netc-pluck sustentation of the string vibration; 'the nvntion being preferably carried out in ths regard by depending at least partially on the mechancal vibratlon of a nonsingng part of the string, say that part of the string beyond a bridge-pece, end preferably between the open agrffe and the bearing-bar, for operating che pulsator 'for current fluctuation.

It s well-known that un electro-magnet can be caused to alter its field of force mch more sm0othly by undulatory current flow rather than by actual make-and-break of the crcut, Whch latter emphaszes the self-nduction a nd re-actnce of the coils of the electro-mag net, and also the impedance due to che hyssteresis of the ron in the magnet core. In

varyng the magnetic fiell sufficently fast t0 synchronize wth the movement of vbraton of the string, every element for causng nonsynchronism, as above, must be considered.

In my co-pending applications Ser. Nos. 178,-

204, and others, filed March 25, 1927, I have' dsclosed end? claimed several forms of current controllers or pulsators which cause undulatoryfiow 0f current, and these pulsators are so constructed as to have no inherent period of vbraton to interfere Wth the synchronc current wave for varyng the magnetic attracton. Nevertheless, there are 0ther elements whch may have periodc vibration and which are necessary for co-ordinating the current controller wth the vibrating string, and the avodance of any eXterior or foreign vibratons in the pulsator from these elements s one of the mportant objects of the present nvention.

Another object of the invention, then, is to provide a pulsator mount so emboded that there Will be avoided any exteror or foregn vbrations, such, for instance, as would result from the inherent pitch of vibration of a part of the pulsator mount.

As the invention s preferably carried out in this latter regard, said mount ncludes the features of a support for a pulsator electrode connected to a part of the piano whch is usually designed to have no disturbng natural pitch of vbration, such as the bea1ngbar, this support ncorporatng 01 associated with a connection, preferably also somewhat rigd, drectly mechancally j oning a pulsator electrode and a non-singing part of the string.

Another object is to provide a method of end apparatus for mountng a pulsator, especially in operative relation to a non-snging nart of a strin 11 such manner that the z: current fluctuat1ons set up 1n the pulsator and the field fluctuations set up in the mag net are, certanly so far as the traned musica1 ear ean detect, pure end unadulterated duplcates, in ampltude end frequeney, and in wave for1n end relat-io'n, of the vibrations of the string, that is unafi'ected by any natural or nherent vibratons of a part or parts of the pulsator or ts mount or of a part 01' parts of the piano itself.

A further object of the present inventon s to provide a mount havng the operative advantages just noted, end wheren, as may be desrable in some cases, only one of the eleotrodes of the pulsator is connected drectly to a part of the mount.

Varous other objects end advantages of the m ention Will be specifically pointed out 01' apparent herenafter, in the course of a description of various preferred of the many possrble forms of the invent1on as shown 111 the eccompanyng drawngs; t being underi s vibrating.

stood, of course, thai; such forms are merely ilustrative of combinatons end arrangemente of parte calculated to attan the objects of the nventon, pursuant to present preference, and hence the deailed descripten of such forms now to be given is not 130 be taken as at all defining or limiting che i1wenton itself. That is to say, the Scope 0f proecaion contemplated s to be taken sciely from the appended claims, nterpreted as broadly as s consstent with the prior art, and with explanatory references 1 0 the specficaton only where a clam is a1nbguous or to be impliedly limted beyond ts express termsto avod such art in order to save the validity of sad clam. 7

In the aceompanying drawings:

F 1 is a diagrammatc vew ilh1st-rating, together wth one form of pulsator and circuit, one form of mount accordng to the i11- venton;

Fig. 2 is an enlarged debail view of certain of the parte as seen in Fig. 1, 'but wth che pulsator shown in axial secton;

Fig. 3 s a view sn11ar t0 Fig. 1, showing another form 01" the invention;

Fig. 4 s un enlmged view in sde eevaton of certan of the parts shown in Fig. 3, but

showing a modifieaton of che mount illustrated in Fig. 4; and

Fig. 5 is a view similar to Fig. 4, but showing stll another modfication of such 1nount. .Referrng to 111 the views, a piano strng s indcated at 10, stretched over the bridge pieces 11 and 12. v

Sad strng after passing over the open agraffe 11a traverses the open space 9 to the tuning pin 8; the length 10a of the srrlng constituting a non-snging part of the str-ing. The electromagnet for vbrating the string by magnetic pluck isindicated at 13, and 14 ndcates the pulsator for controlng sad magneti, sad pulsator beng located in a circuit with,the magnet, whch crcuit includes a suc-able source of energy 15 and a swtch 16 operated by the piano key 17 when che latter is depressed. 7

The hammer for the string s conventionally ndicated at H, and the bearing-bar at B.-

Thepulsator 14 is connected no that part of the length 10a of the string which extends between the agraffe 11a and the bearingr-bar B. The only vbration ths. porton of the string can have s a very minute 0ne, due io che flexure of the string when the maln portion thereof between the bridges 11 and 12 The string vibrates in a 'plane at rght angles io that of the sounding-board; and the length 19a of the string moves similarly. I have feund that ibis latter movement s suflcent to cause differences in "che conductivity of the pulsator 14 well adapted te control the action of magnet 13 to give true sostenuto.

The pulsator of Figs. 1 and 2, in the present case, includes a par 0f coactng electrodes 18 and 19, whch may be 0f squat eylindrical shape, spaced t0 form a. chamber beoween their opposng faces for a collection 20 of grzinular carbonaceous material or the like, a cylindrical s1eeve or tube 25 of fibre, felt or the lke, being applied to hold together the other pulsator parts already referred t0.

fiere, contro1 01" the magnet for true sostenuto s a funct-on of a direct meehanical connection between the string and one of the electrodes, as the connecton 26. In the form of the nventionshown in Figs. 1 and 2, further, there is a direct mechanical connection between the other electrode and the bearingbar, as the connection 27; which latter connecton acts, in combinaton wth the other parts, to prevent the sett-ng up of apprecable nherent perodic vbration in the pulsator and its mount of a nature to disturb che natural vibraton 01 the string 10.

Sad connection 26 is a somewhat rigid strip having 2111 upbent end screwed to che electrode 19, as shown, and its other end sutably secured to 01' resting on the string along the length 10a thereof between bridge 11 and bar B.

Said connection 27 is a relatively very rgd support or bracket. Ths bracket is fastened to the bearng-bar B and has a downturned length Whch suspends the outer porton of the pulsator, beng clamped to the electrode 18 by means of a threaded stud 28 set in said electrode and carrying adjustng nuts 29 and 30.

After the pulsator s properly located, the nuts 29 and 30 permit of adjustng che electrode 18 to obtan the proper conductvity througlrthe collection 20, and still permit vibratory movement of the electrode 19 as impulses are transmtted through connection 26.

Therefore, any movement imparted to the electrode 19 through the connecton 26 will cause a compactng of the granular contents of the pulsator end cause a change in the conduct-ivity of seme; the outer electrode 18 being so held by the bracket 27 as to prevent any definite moton of said electrode.

T0 avoid short-circuiting che pulsator 14, conneetion 26 or bracket 27 is desirably of nomconductng material.

Referring to the form of the invention shown in Figs. 3, 4 and 5, ths shoWs, first, that a dfierent pulsator from that of Fig. 1, and also a different mount from that of F g. 1, may be employed pursuant to the inventi0n. A pulsator 14m reste or is secured in any ordinary or convenient wa v on a suitable bar or plate marked 22m in Fig. 3, 22g in Fig. 4 and. 222 in Fig. 5. Near the inner end of such plate in.each case, the same is clamped,

wedged or otherwise stracldled abont or rested on the string between the agraffe 11a ancl bearing-bar B. The pulsator comprses in each instance a pair of cooperating electrocles with an interposed mass of carbon grannles or the like, as is shown in detail in my copencling application Serial No. 17 8,204, March 25, 1927. One of these electrodes is rigidly connected with a piano string by means shown, such means including the plate whieh is fastened to the piano string, and whichhas secured thereto a sleeve of fiber or the like in whieh che electrocle is affixed. T he con1panion electrocle is loosely contained in an envelope of felt, wool, yarn or the lil:e which fits inside the sleeve as to hold the eleetrocle in proper relationship to the granulzu mass, a wrapping of yarn being previcleel to hold the enter portion of the envelope to the supporting bar, and a pad of felt being nterposecl beneath the ot-her end of the pad and envelope as a further cnshon medium.

The non-resonant electrocle is relatively heavy; in other worcls, is 0f sufiicient mass t0 give it such ineltia that it Will operate in effect as an anvil for the lighter clirectly actuatecl hannner, ancl being supportecl as it is in a non-resonant envelope, its motion l'elative to the other electrocle, is slght end of less frequency.

In each of the variations of the form of mount shown in Figs. 3, 4 and 5, a strut 23 is secured ab its inner end to the bearingbar ancl near its outer end suspencls a thread 01 wire 24 which is fastened to the plate 22m, 22y 01 222 near its enter end, f0r instance as indicated at 24a, where the wire 2 is drawn through a hole in the plat ancl knottecl below such hole.

In F ig. 3, the main mount or plate 22m is shapecl as indicatecl ai; 22a, so it may be adjusted to i1npinge as shown against the bearing-bar.

In Fig. 4, the main mount or plate 22g is straight ancl clamps the string 10 so that the nner end 22?) of such 1nan mount may impinge upon the pin-plate 38.

In Fig. 5, the main mount or plate 222 is also sraight, bui) is. so shapecl, as by properly shaping an end fork-wedge, as to be adjust-able for impingement against tbe agrafle hacking 112).

In installation, after the main mount 22m, 22g or 222 is clampecl to the string 10, the thread 24 is tautenecl until the main monnmakes contact with the lower edge of the bearing-bar B, as in Fig. 3, or impinges upon the agraffe backing, as in Fig. 5. In Fig. 4, the th ead isn0t reliecl on to secure i1npingement of the main 1nount against the pin-plate 20 and, insteacl, proper clamping of the main monnt on the string is reliecl on for such impingement.

It Will be noted that in che variations of Figs. 3, 4 and 5, each plat-e or 1nain 1nount 2200, 22g 01 222 has what ean be termecl a threepoint suspension, in che sense that this supporting member has contacts with the bridge piece, and strng, and is supported at its fart-her end as by the cord 24; and this hree-point suspension, I have so far found, acts apparently as theicleal arrangement f01' eliminating or dulling any tendency in any part ancl particularly in the main mount to vibrate according to its own natural or inherentperiod; while, at the same time, al thongh the motion impartecl to the pulsator is very minute, because imparted from a nonsinging part of the string, I fincl that adequate and full-volume sostenuto is obtained.

It Will be further notecl that the modificatiens 0f Figs. 3, 4 and 5 difler from the form 0' ll1e invention shown in Figs. 1 and 2; in chat in Figs. 3, 4 and 5, there is no direct mechanical eonneccon fro1n either electrode to any portion of the string 10. The electrodes in this case act by inertia te produce the current varations.

Inasmuch as many changes could be made in the above construetions, and many apparently wiclely diflerent embocliments of my invention could be made withoutdeparting from the scope thereof, it is intended that all metter contained in the above description or shown in the accompanying clrawings shall be interpreted as illustrative and not in a li1niing sense.

Itis also to be understoocl thatthe langnage contained in the following claims are intenclecl to cover all the generic ancl specific features of che invention herein describecl and all statement-s of the scope of the invention which, as a matter of langnage, might be said to fall therebetween.

Vhat I clam is:

1. In an electric sostenuto piano, che combination of a string, a pulsator, a magnetin circuit with ancl actuatecl by said pulsator te sustain the vibration of a string, means f01 imparting vibrations (o tlie pulsator from vibratiens of the string, and 1neans for exclucling from the pulsator such other vibrations as Will, to an extent audibly appreciable, interfere with ti-ne sostenuto.

2. In an electric sostenuto piano, che combination of a string, a pulsator, a magnet in circuit with anc'l actuated by said pulsator te snstain the vibraion of a string, means f0r i1nparting vibrations to the pulsator f10111 vibrations of the string, a clevice for starting the string to vibrate first to sound the fundamenal and then the funclamental and the partials, ancl 1neans for insuring that mag- HG'C sustentation of the string vibration Will be initiatecl after such partials have begun to be sounclecl.

3. The piano defined in clai1n l, wherein the last-mentioned 1neans includes a suspension for the pulsator incorporating a. fixed bracket and a connection vbrat-ng wt-h the string.

4. The piano defined in clam 1, wheren thc last-mentoned means ncudes a suspension for the pulsator ncorporatng a comparatvely rigid bracket fixed to a part of the piano free of a period of vbraton apprecab1y out of phase Wfih that of the string, and a so1newhat lcss lgd mcchanica conneccon vbmting vvth the string.

5. In an electric sostenuto piano, the combination of a string, a. pusator, a magnetn circut wth and actuated by sad pulsator to sustan the vbraton of a. string, means for impartng vibratons to the pulsator from vibratons ci che strng, whlc suspending the pulsator as a unit, and means for excluding from the pulsator snch other vibratons as Wll, to an extent auclbly a.pprecable, nterfere wth true sostenuto.

6. The method 01 obtaining sostenuto ef fects in an electrcaly vibrated piano strng Whch consss in utlzing thc nomsnging part of the string for controng the current servng to cause vbration of the singng part of the string.

7. The method of obtanng sostenuto effects in a piano strng havng an electromagnetc contro for the vibratons 01 the sngng part of the string which conssts in varyng the electro-magnetc strength by means of the vbrasons induced in the nonsinging part of the string by the vbratons of the snging part of said siringa 8. The method cf ebtaning sostenuto effects in a piano srng havng an electromagnet arranged to act on the sngng part of the string as an armature whch consists in alternately ncreasing and decreasing the strength of the crcut tbrough the magnet by utlizing the vibrations of tbe non-singing part of the string to efiect changes in sa1d cnrrent strength.

9. In a 1312L110, a str1ng, an electro-magnet supported near said string to vibrate the same, a pulsator controlled by the vbration of sad string and connececl in seres wth the winding of sad magnet, and a three point suspenson of character defined for sad pulsator.

10. In a piano, a strng, an electro-magnet supported near sad strng to vbrate the same, EL pulsator controlled by the vbration 0f sad string; and connccted in scres Wth hc wnding of said magnet, and a three pont suspenscn of character defined f01 sad pulsator, sad piano havng non-vibratle parts tdwhich tw0 ponts of the suspcnson are attachecl.

11. In a piano, a. string, an electrc-magnet supported near sad strng to vibratc the same, a pulsator contnoled by the vbraton of sad string and connected in seres with the wndng ci sad magnet, and a three point suspension of character defincd for said pulsator one of which is a point upon the string.

12. In a piano, a string, an electro-magnet supported near said string to vibrate the saune, a pulsator controlled by the vbration of sad string and connected in series with the winding of sad magnet, and athrec point suspenson of character defined for said pulsator one of which s a point upon a nonsingng part of the string.

13. In a piano, a string, an electro-magnet supported near said string t0 vibrate the saune, a pulsator controllcd by the vibration of sad string and connccted in sercs wth the winding of said magnet, and a three pcint snspenson of character defined for said pulsator one of which s a point upon the string havng a relatively minute axnpltude of vbrationas compared wth another part 01: said strng.

14:. In a piano, a strng, an electro-magnet supportcd near sad strng to vibrate the same, a pulsator controlled by the vbration of said strng and connected in scries with the Wndnp; of said magnet, and a three pont suspension of character defined for sad pulsator, one mcmber of sad. suspension consisting of a suspensory filament having a bearng pointon the string.

15. In a piano, a string, an electro-magnet supported near sad string to vbmte the samc, 2L pulsator controlled by the vibration ci sad string and connected in seres with the wnding of sad magnct, a mcmbcr attached to a fixed part of the piano, a mounting mcnnbcr for sad pulsa'cor including a mcmber bearing on said strng and located beneah the last member, and a flexible filamcnt connecting the free ends of said members.

16. In a piano, a strng, an electro-magnet supported near sad strng t0 vbrate the same, a p'ulsator controlled by the vibraton of sad strng and connectcd in scres With the wndng 0f said magnet, a mcmber attached to a fixed non-vbratile part of the piano, a mounting member for said pulsator ncludng a. member bearing on sad string and located beneath the last 1ne1nber, and a flexble filament connectng the free ends of sad members.

17. In EL piano, a strng, un electro-magnet supported near sad strng to vbrate the sume, a pulsator controlled by the vibraton of sa string and connected in sercs with the wndng of sad magnet, means t o suspend the pulsator from a part of the piano other than the string, and a brace extending f'2oxn the pulsator to the string.

18. In a piano, a. strng, an electro-magnet supported near sad string to vibrate the same, a pulsa/nor controllcd by the vibration of sad string and connectcd in series wth Che windng of said 1nagnet, means to suspend the pulsator frcm a. part of the piano other than the string, a brace cxtendng from the pulsator to the string, and a second brace extending from the pulsator to a part of the piano other than the string.

19. In a piano, a string, an electro-magnet supported near said string to vibrate the same, a pulsator controlled by the vibration of said string and eonnected in series with the winding of said magnet, means to suspend the pulsator from a pari of the piano other than the string, and a brace extending from the pulsatoi to a bridge piece of tbe piano.

20. In a piano, a string, an electro-magnet supported near said string to vibrate the same, a pulsator controlled by the vibration of said string and connected in series with the winding of said magnet, and a three point suspension of charaeter defined for said pulsator, one of said points being vibratile.

21. A sostenuto piano or simiiar instrumeni: comprising in combination Wii h tbe vibratory string, bridge, and bearing bar, a pulsator including t-wo electrodes and comminuted conducting material between thenr a direct connection from one elect-rode to non-singing part of the string, and a nonresonant supporting member connected to the other electrode and to an adjacent fixed part of the piano structure.

22. A sostenuto piano or similar instrument comprising in combination with the vibratory string, bridge, and bearing bar, a pulsator including two electr0des and 001 minuced conducting material between them, an arm connected to one eieetrode and 130 a nomsinging part of the string adjacent "che bridge, and a supporting bracket connected to the bearing bar and to the other electrodes.

23. A sostenuto piano or similar instrument comprising in combination Wifh th e vibratory string, bridge, and bearing bar, a poisator, a supporting member on which the pulsator is located and engaging the bearing bar and the string at a point near the bearing bar and between the latter and the bridge, an ad ditional support connected to a stationary non-resonant part of the piano structure, and a flexible no1rresonant connection therefrom to the first named support near ics end remote from the string.

24. A sostenuto piano or similar instru ment comprising in combination with the vibratory string, bridge, and bearing bar, a

pulsator, a supporting member on wbich che pulsator is located and engaging the bearing bar and the string at a point near the bearing bar and between the latter and the bridge, an additional support eonnected to a stationary non-resonant part of the piano structure, and a thread-like element connecting the last named support to the first support at a point remote from the string.

25. A sostenuto piano or similar instrumeni; comprising in combination with the vi bratory string, bridge, and bearing bar, a pulsator, a supporting mernber on which the pulsator is located and engaging the bearing bar and the string at a point near the bearing bar and between the latter and the bridge, an additional support connected to the bearing bar, and a thread-Iike element connecting the last named support to che first support at a point remote from the string.

26. A sostenuto piano or similar instrumeni; comprising in combination with the Vibratory string, bridge, and bearing bar, a pulsator, a first support on which the pulsator is mounted and at one end engaging a nonsinging part of the string adjacent the bridge and al so at that end engaging a stationary non-resonant part of the piano structure adjacent the bridge, an auxiliary support connected to a stationary and non-resonant part of the piano structure adjacen: the bridge, and a flexible non-resonant connecion from said auxiliary support to the first support at a point near its end remote from the string.

27. A sostenuto piano or similar instrument comprising in combination with the vibracor string, bridge and bearing bar, a pul sator, a first support 011 which the pulsator is mounted and at one end engaging the string at a point adjacent the bridge and between the latter and the bearing bar and also at that end engaging the bridge, an auxiliary support connected at one end to the bearing bar, and a thread-like element connecting th-e auxiliary support to the first named support at a point near its end remote frena the string.

28. A sostenuto piano or tb.e like comprising in combination with the vibratory string, a pulsator including electrodes and comminuted conducting material betvveen them, a connection from the string to the pulsator, and a non-synchronously-resonani: supporting member connected to the pulsator and to an adjacent fixed part of the piano structure.

29. A sostenuto piano or similar instrument comprising in combination with the vibratory string, bridge, and bearing bar a pulsator including two e:.ectrodes and comminuted eon ducting material between them, a direct connection from one electrode so che string, and a non-synchronously-resonant supporting member conneeted to the other eectrode and to an adjacent fixed part of the piano structure.

In testimony whereof I afix my signature.

SIMON COOPER.

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