US3215766A

US3215766A - Fixed-free-reed electronic piano with electrodynamic translating means controlling the odd and even partialfrequency components

Info

Publication number: US3215766A
Application number: US418716A
Authority: US
Inventors: Benjamin F Miessner
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-12-16
Filing date: 1964-12-16
Publication date: 1965-11-02
Anticipated expiration: 1982-11-02

Description

Nov. 2, 1965 B. F. MIESSNER 3,215,766

FIXED-FREE-REED ELECTRONIC PIANO WITH ELECTRODYNAMIC TRANSLATING MEANS CONTROLLING THE ODD AND EVEN PARTIAL-FREQUENCY COMPONENTS Filed Dec. 16, 1964 2 Sheets-Sheet 1 A TTO/P/VEV s 3L0 1 x JINVENTOR.

Nov. 2, 1965 B. F. MIESSNER 3,215,766

FIXED-FREE- EED ELECTRONIC PIANO WI ELECTRODYNAMIC TRANSL NG OLLING THE ODD AND MEA CO EVEN TIAL-FREQ CY COMPO TS Filed Dec. l 4 Sheets-Sheet 2 BENJA IN F. M/ESSNER A T TORNE V United States Patent FIXED-FREE-REED ELECTRONIC PIANO WITH ELECTRODYNAMIC TRANSLATING MEANS CONTROLLING THE ODD AND EVEN PARTIAL- FREQUENCY COMPONENTS Benjamin F. Miessner, 680 NE. 105th St., Miami Shores, Fla. Filed Dec. 16, 1964, Ser. No. 418,716 15 Claims. (Cl. 841.14)

This invention relates to an electronic piano, and more specifically to such a piano of the type wherein electric oscillations are translated from the decadent free vibrations of fixed-free reeds which are respectively provided for the several note-s of the pianos scale. As to each reed the vibration of importance is its first-partial or fundamental vibration; in the translation of the electric oscillations from that vibration there are introduced into those oscillations multiple-frequency oscillation components harmonically related to that vibration, thereby to achieve pianistic tonal quality. Excitation and/ or translation of upper-partial vibrations of the reed not harmonically related to its fundamental vibration is or are contemplated to be minimized or avoided; techniques for this purpose, being elsewhere disclosed or otherwise known, are not specially dealt with herein.

An important aspect of the present invention concerns the means employed for the translation above referred to. In a number of earlier patents issued on applications of mine I have shown electrostatic, or capacitative, translating means which, in order to perform the function of introducing the multiple-frequency oscillation compo nents, has been positioned so as to be swept past by the reed in at least its higher-amplitude vibrations. This structure has the advantage of great simplicity. But it produces in the translated oscillations an electric wavefront of the same polarity each time the reed passes it, whichever be the direction of that passage; thus were that means to have been centered with respect to the reeds vibratory swing (i.e. aligned with the reeds rest position) the oscillations would have been of fundamental frequency double that of the reed, and would have contained harmonic partials restricted to even-numbered multiples of the reed frequency.

To avoid this obviously undesirable effect those disclosures have shown the electrostatic translating means slightly decentered with respect to the reeds vibratory swing (i.e. displaced from alignment with the reeds rest position), and this has of course resulted in the appearance in the translated oscillations of components corresponding to the fundamental frequency of the reed vibration and to odd-numbered multiples thereof. Each of these, however, is of small amplitude at large amplitudes of reed vibration, and actually increases as the vibrational amplitude decays from those large amplitudes to an intermediate one; this not only results in an excessive shift of harmonic structure in the early portions of a louder tone but also, because the fundamental is of especial importance in the impression created by the tone, renders the louder tones organesque rather than percussive or pianistic in character. Moreover in the later portions of the tones the multiple-frequency components decay at an excessive rate, and each tone tends to end with little excepting fundamental-which is in itself abnormal, and furthermore in the case of very low-frequency tones results in an excessively rapid falling of the tone below the threshold of audibility. These shortcomings, which constitute a significant blemish on the pianistic quality of the output tones, are the direct result of the fact that the simple electrostatic translating means above referred to translates wavefronts of the same polar- 3,215,766 Patented Nov. 2, 1965 ity in response to oppositely directed sweeps of the reed, and of the reliance on the abovementioned decentering (or displacing) expedient for the elicitation of the basically important fundamental component (as well as oddnumbered multiple-frequency components) of the oscillations.

I am aware that, among translating means which may be bidirectionally swept past by the reed in each cycle of its higher-amplitude vibration in order to achieve the introduction of multiple-frequency components, there are some which produce in the translated oscillations wavefronts of opposite polarity in response to the oppositely directed sweeps of the reed. Thus for example in one earlier patent issued on an application of mine (No. 3,038,363, in which, see Sheet 9 of the drawings) I among other things disclosed, for a fixed-free-reed electronic piano, various electromagnetic translating means of which those shown in FIGURES 49, 50, 51, 53 and 54 are bidirectionally swept past by the reed in the above stated manner and do introduce multiple-frequency components-among which in turn that one shown in FIG- URE 53, if used with longitudinal magnetization of the reeds (as alternatively disclosed in column 31 of the patent), will translate oscillations containing the fundamental and odd-numbered multiple-frequency components. (The others of the several figures above referred to will produce only double-frequency and other evennumbered partials.) I have also become aware, however, that the oscillations translated by that FIGURE 53 structure (with longitudinal reed magnetization) from the fundamental reed vibration wholly fail to include any components whatever at even-numbered multiples of the reeds fundamental vibrational frequency. The result of this failure is an output tone which, while not suffering the shortcomings mentioned in the preceding paragraph, sufiers another serious shortcoming: the unpianisticfhollowness characteristic of tones which contain only oddtions of components at even-numbered multiples of the reeds fundamental frequencyand will do so in a manner well suited to the achievement of a pianistic output-tone quality. This is not without a considerable element of surprise, in view of the fact that with the other type of translating means (first above discussed) it was that same decentering (or displacing) of the translating means which:

served to introduce components at odd-numbered multiples of the reeds vibrational frequency. I have, furthermore, found it to be a procedure which does not suffer from any shortcoming comparable to the above-discussed limitation on the amplitude of fundamental (and odd-numbered multiple-frequency) components which can be added in the case of the other type of translating means. (While I do not undertake to present a complete explanation for this observation, it appears to me on analysis to be related to the proposition that both the presence and the rate of change of the fundamental component in the output tone are of elementaryjmportance in pianistic quality, cannot be compromised, and can only be assured as a result of some basic, rather than a secondary, aspect of the structurewhile the presence and rate of change of the even-numbered multiple-frequency components, while qualitatively important, are not of great quantitative, criticality. It may well also and independently be due to the facts that the introduction of even-numbered multiple-frequency components by decentering involves a desymmetricalizing of the waveform and that this geometrically increases at the lower vibrational amplitudes at which the degree of multiple-frequency introduction is inherently the least, so that an inherent compensation-quite absent in the converse caseis automatically achieved.)

In the above-discussed aspect the invention comprises the use with the fixed-free reed of an electronic piano of an electric translating means, having a portion located adjacent to and influenced by an edge portion of the reed and bidirectionally swept past by the reed in each cycle of the reeds higher-amplitude vibration, for translating from the reed vibrations electric oscillations comprising wavefronts of respectively opposite polarity in response to the oppositely directed sweeps of the reed, whereby the oscillations are caused to contain components of the fundamental frequency of the reed vibration and odd-numbered multiples thereof, that translating-device portion being displaced from alignment with the rest position of the reed whereby to cause those oscillations also to contain components of even-numbered multiples of the reeds fundamental frequency.

In another aspect the invention concerns a preferred translating means of the type first mentioned in the preceding paragraph (i.e. of the type which translates oscillations comprising wavefronts of respectively opposite polarity in response to the oppositely directed sweeps of the reed). I have found especially favorable, from the viewpoints both of simplicity and effectiveness, an electrodynamic form of translating means comprising an electrical' conductor adjacent a free edge portion of the reed and bidirectionally swept past by that edge portion in each cycle of the reeds higher-amplitude vibration, means creating a magnetic field transverse to the conductor in the region adjacent that edge portion, an electrically conductive loop in which the conductor is serially included, and output means responsive to the current generated in the loop by the vibrating reedthe reed comprising magnetic, if not also magnetized, material.

Subordinately as to the aspect last stated, the abovementioned edge portion of the reed may be the reeds free end. The field-creating means may be a magnet fonming the free-end portion of the reed. Alternatively the field-creating means may comprise a magnet disposed on the opposite side of the conductor from the free end of the reed; in that case, to avoid undesirable reaction from the magnet on the reed vibrations in the case of a lowerfrequency reed, the surface of the magnet facing the free end of the reed may be arcuate and substantially equispaced from that free end as the reed vibrates. Still alternatively the reed may be of magnetizable material and may be magnetized to itself constitute the fieldcreating means; in that case, to achieve good magnetization without risk of reed breakage at or near its fixed end, the reed may be of harder material in its free-end portion and may there be magnetized. To maximize the introduction of multiple-frequency components throughout the scale in spite of progressively diminishing maximum vibrational amplitudes toward the upper end of the scale, the thickness of the conductor, and of the magnets forming the free-end portions of the reeds (when employed), may be progressively reduced toward that upper end.

Still another aspect of the invention is related to the first. It may be desired very precisely to predetermine the general balance between evenand odd-numbered partials in the output oscillations of the system; on the other hand it may be desired from time to time to vary that balance for deliberate variation of tonal effects. To achieve either of those and/or other possible objectives the invention optionally contemplates the use, with the reed, of two translating means each of the type (above referred to) which translates from the reed vibrations electric oscillations comprising wavefronts of respectively opposite polarity in response to the oppositely directed higher-amplitude sweeps of the reed, the respective portions of-those two means adjacent to and influenced by the edge portion of the reed being spaced from each other in the direction of the reed vibration, together with means connected with the two translating means for combining oscillations from each in a selected relationship. Typically, though not necessarily limitatively, the abovementioned portion of one (of course, one only) of those translating means may be aligned with the rest position of the reed.

The aspect set forth in the preceding paragraph will ordinarily be embodied in a structure wherein each of the respective portions of the two translating means adjacent to and influenced by an edge portion of the reed is bidirectionally swept past by the reed in each cycle of the reeds higher-amplitude vibration but at least one of those respective portions is not thus swept past during useful lower-amplitude vibration of the reed. In such an embodiment that aspect does not necessarily depend for its novelty on the limitation that either or both of the translating means be of the type which translates from the reed vibration electric oscillations comprising Wavefronts of respectively opposite polarity in response to the oppositely directed sweeps of the reed; itmay accordingly be re-stated without that limitation as another, though related, aspect.

Various objects of the invention have been made apparent by the foregoing brief description. Allied and other objects will be apparent from the following detailed description and the appended claims.

General objects are the provision of an improved electronic piano of the type wherein electric oscillations are translated from the decadent free vibrations of fixedfree reeds, and the provision of improved translating means for such a piano. Another object is the provision of an improved reedor vibrator-exciting action.

In the detailed description of the invention reference is had to the accompanying drawings, in which FIGURE 1 is a bottom plan view of the reed-and-translating-means assembly of an electronic piano according to the invention, together with a schematic showing of certain electrical apparatus associated therewith;

FIGURE 2 is a vertical cross-sectional view taken along the line 2-2 of FIGURE 1 (the line 11 in FIG- URE 2 indicating the plane along which FIGURE 1 is taken) and also fractionally illustrating a reed-exciting hammer action for the reed appearing in FIGURE 2;

FIGURE 3 is a vertical cross-sectional view taken along the line 3-3 of FIGURE 1;

FIGURE 3a is an enlarged view of a small portion of FIGURE 3;

FIGURE 4 is a vertical cross-sectional view taken along the line 44 of FIGURE 1;

FIGURE 4a is an enlarged view of a small portion of FIGURE 4;

FIGURE 5 is a vertical cross-sectional view taken along the line 55 of FIGURE 1;

FIGURE 6 is a vertical cross-sectional view taken along the line 6-6 of FIGURE 1;

FIGURE 7 is a View generally similar to FIGURE 4 but illustrating a modification in respect of the magnetic field-creating means;

FIGURE 8 is a view generally similar to FIGURE 4 but illustrating a further modification of the magnetic field-creating means; and FIGURE 9 is a plan view alternative to FIGURE 1 illustrating a modification of the layout of the reeds and reed-supporting frames.

In the description of the electronic piano shown in FIGURES 1 through 6 of the drawings reference may first conveniently be had to FIGURE 2, which is a vertical cross section through the lowest-frequency reed R Herem there will be seen a generally L-cross-sectioned frame 1 of relatively hard metal (such as a suitable aluminum alloy) of which the shorter leg 2 is a downhanging vertical one through which there passes a horizontal hole 7. The fixed end of the reed K, may be fitted into l a longitudinal slot 8 formed in one end portion of a generally cylindrical plug 9 of deformable metal, and that plug may then be axially force-fitted (its other end first) into the hole 7 to provide a rigid clamping of the reeds fixed end to the frame 1. The longer leg 3 of the frame extends forwardly above the reed R typically to a little further than the reed itself extends; to its end face there may be secured a downhanging member 4 of non-magnetic and preferably insulating material, which may be used as a support for elements hereinafter de scribed.

Below and to the rear of the frame 1 there may be pivotally mounted to a suitable support the butt 18 of a hammer 10 whose shank 17 extends from the butt and at its free extremity carries a hollow cylindrical hammer head 11 which is directed upwardly toward the reed and at its upper end carries a reed-contacting pad 12 hereinafter further referred to. The hammer may be rocked about its pivotal mounting, so that the pad will strike the reed to set the reed into decadent vibration, by a conventional piano key 20 coupled to the hammer butt 18 by an elongated capstan 21. The geometry of the system may be so arranged that the mean point of strik ing of the reed by the pad 12 is at approximately onequarter of the length of the reed away from the plug 9.

Reference being had to FIGURE 1 (in which one looks upwardly at frame and reeds) it will be seen that the frame 1 is laterally extended to carry a number of reedsfor example thirty-one, of which the lowest-frequerrcy reed is R; and the highest frequency reed R In this lateral extension the thickness of the vertical leg 2 is tapered in a linearly increasing manner and the length of the horizontal leg 3 is tapered in a linearly decreasing manner; this, done in view of the progressively diminishing lengths of the reeds for successively higher frequencies, is carried out with the forward surface of the vertical leg 2 and the forward edge of the horizontal leg 3 each angled with respect to the front of the piano, and with the mean points of striking of the several reeds by their respective hammers forming a straight line (designated as L) parallel to that front.

For a succeeding group of reeds, typically the next twenty-four, there may be provided a second frame having vertical leg 2a and horizontal leg 3a, the thickness of the former and the length of the latter again being linearly tapered but in reduced degree. For a further succeeding group of reeds, typically the next eighteen, there may be provided a third frame having Vertical leg 2b and horizontal leg 3b, the thickness of the former and the length of the latter again being linearly tapered but in further reduced degree. And for a final group of reeds, typically the last twelve, there may be provided a fourth frame having vertical leg 20 and horizontal leg 30, the thickness of the former and the length of the latter being still again linearly tapered but in still further reduced degree.

Downhanging members

4a, 4b and 4c, corresponding to member 4, may be provided for the second, third and fourth frames respectively.

Each of the reeds (K; through R carried by the first frame and each of those (R through R carried by the second frame is shown as having a free end portion comprising a magnet which is magnetized longitudinally of the reed. These magnets may be of the ceramic variety; they may for example first be copper-plated, and then butt-soldered to the end of the reed proper. All these magnets may for example have a width (i.e. dimension transverse of the reed) of about and a thickness of about ,4 (contrasting with typical reed-proper width and thickness of about A3" and & respectively); Those magnets which are comprised in the first thirteen reeds may for example have a length (ie dimension longitudinal of the reed) of about A", those comprised in the next nine reeds a length of about A3", and those comprised in the remaining ones ga e 6 of the magnet-comprising reeds a length of about 6 Tuning of the magnet-comprising reeds may be accomplished by the incorporation of appropriate amounts of extra solder secured to the reed, preferably at the region of juncture of the magnet with the reed proper. Thus with respect to the reeds carried by the first frame, FIGURE 1 by way of example shows at that region on reed R.,, a substantial fillet R; of extra solder, but no substantial extra solder on reed R at that region on reed R a substantial fillet F of extra solder, but no substantial extra solder on reed R and at that region on reed R a substantial fillet F of extra solder, but no substantial extra solder on reed R On the reeds carried by the second frame no substantial extra solder is actually illustrated, as the progressive lengths of its reeds are nearly enough correct to avoid the need for substantial extra amounts.

Each of the magnets comprised in the reeds R through R is designated by the letter M followed by the same numerical subscript as used for the respective reed.

The reeds carried by the third and fourth frames are shown as simple reeds, not comprising any magnets; they are, however, of magnetic material (as the reeds proper in the case of the earlier-described reeds preferably also are). In the case of each of those two frames the progressive lengths of its reeds are nearly enough correct to avoid the need for major tuning expedients, and they may be tuned by the usual finetuning techniques. It may also be noted that the lowest-frequency reed (R carried by the third frame is shown as somewhat longer than the highest-frequency reed (R carried by the second frame in view of its being the first reed without the loading effect of a contained magnet.

FIGURE 2, illustrating the reed R and the exciting means therefor, has already been referred to. FIGURES 3, 4, 5 and 6 respectively illustrate the reeds R R R and R For simplicity FIGURES 3 and 5 omit any showing of exciting means, and FIGURES 4 and 6 show such means only fractionally; it will of course be understood, however, that a respective key-and-hammer action will be provided for each reed of the piano, in accordance with conventional practice.

The reeds and their mounting and their exciting means having been thus described, attention may be directed to the preferred translating means according to the inventions second aspect introductorily stated above.

Adjacent a free edge portion of the reedtypically the reeds free cndI place an electrical conductor bidirectionally swept past by that edge portion in each cycle of (at least) the higher-amplitude vibration of the reed; such a conductor is shown in FIGURES 1 through 6 as 30, lying in the plane of the reeds, supported in any convenient manner or manners (not illustrated) to

members

4 and 4a and in manner hereinafter described to

members

4b and 4c, and formed into close adjacency to the free end of each reed. I provide an electrically conductive loop in which that conductor is serially included; FIGURE 1 shows this loop as formed by the conductor 30 with the one or fewturn primary 31 of a transformer 33, the portion of frame 3c intervening between connecting screws 50 and 6c, the conductive jumper 290, the portion of frame 3b intervening between connecting screws 5b and 6b, the conductive jumper 2915, the portion of frame 3a intervening between screws 5a and 6a, the conductive jumper 29a, and the portion of frame 3 intervening be tween connecting screws 5 and 6 (at which latter the conductor 30 may be considered as beginning). And with respect to each reed I provide means creating a magnetic field transverse to the conductor in the region adjacent the reeds edge portion (e.g. free end); with respect to each of the reeds carried by the first and second frames this means consists in the respective magnet already described as comprised in that reed.

With respect to each of the reeds carried by the third and fourth frames the field-creating means is shown in FIGURES 1, and 6, as consisting of a magnet disposed on the opposite side (e.g. forwardly) of the conductor 30 from the free end of the respective reed and magnetized in a direction longitudinal of the reed. For each such reed the respective magnet is designated by the letter M together with the same numerical subscript as used in the designation of that reed. Each magnet may be secured in any convenient manner to the bottom of the

downhanging member

4b or 4c (as the case may be), and may in turn form a means supporting the conductor 30. By way of example these magnets are shown as each approximately long and A" wide, with those carried on memlber 417 (see FIGURE 5) each about A" thick and those carried on member 4c (see FIGURE 6) each about /8" thick.

It will be understood that, in the case either of the reedincluded magnet or of the stationary separate magnet, a field is created transverse to the conductor 30 and longitudinal of the reed. In the case of each of the magnet-including reeds this field will pass through the conductor 30 without concentration; in the case of each of the other reeds it will converge, in passing through the conductor, to concentrate itself in the free end of the reed in view of the magnetic nature and hence low reluctance of the reed material. In either case the vibration of the reed will cause the lines of force (which make up the field) to cut the conductor 30, the effect of which is to induce an oscillatory current in the conductor and thus in the abovedescribed loop in which it is included.

The electric oscillations of which that oscillatory current consists are of course translated from the reeds vibration (which will here be assumed to be essentially only at its fundamental frequency). Because the direction of instantaneous current flow in the conductor 30 depends on the direction in which the magnetic field cuts the conductor, the wavefronts respectively produced in the translated oscillations by the up and down sweeps of the reed will be of opposite polarities, with the result that the translated oscillations will contain a substantial component at the fundamental frequency of the reed vibration. Because the reed sweeps by the conductor 30at higher vibrational amplitudes, very rapidly and through two very restricted portions only of its cyclethere will be introduced into the oscillations components at frequencies which are multiples of that fundamental frequency. But, with the conductor 30 in its described and illustrated position of alignment with the rest position of the reed so that it is centered with respect to the reeds vibratory swing, those multiple-frequency components will be at odd-numbered multiples onlyusually a distinct disadvantage of which mention was made above.

I have found that if instead of the conductor 3t) there be employed a conductor 40 somewhat decentered with respect to that swing, or displaced from alignment with the rest position of the reed, components at even-numbered as well as at odd-numbered multiples will be introduced.

Such a conduct-or 40 will be seen in FIGURES 1 through 6, positioned somewhat above but otherwise similarly to the conductor 30. It is serially included in a loop which, in addition to the conductor 40, includes the oneor few-turn primary 41 of a transformer 43 and a conductor 39 leading from that primary to the lefthand end of the piano (where the conductor 40 may be considered to start) and there merging with that conductor 40.

It may be mentioned that in order to acco-modate the showing of the conductor 30-whose presence jointly with the conductor 40 is contemplated according to aspects of the invention yet to be detailed describedthe conductor 40 has beenillustrated in a higher poistion than the preferred one which it would occupy if the conductor 30 were not present. In general, that preferred position of the conductor 40' when used alone would be one displaced from alignment with the reeds rest position by a fraction only of the degree by which that conductor has been shown as displaced in the figures.

With the conductor 40 occupying its preferred position as just described, there are produced in it oscillations representing excellent pianistic quality, with thoroughly satisfactory even-numbered (as well as odd-numbered) multiple-frequency components and without any of the deficiencies as to fundamental component which were introductorily described.

The separate magnets shown in connection with the reeds carried by the third and fourth frames should in general be of thickness sufficient so that the swing of any reed does not carry its free end appreciably above or below the respective magnet. Accordingly for the highestfrequency reeds (whose maximum swing is small) the use of a thin magnet as in FIGURE 6 is permissible, while for somewhat lower-frequency reeds (whose swing is greater) a somewhat thicker magnet as in FIGURE 5 is called for.

The separate-magnet structure may be carried on downwardly in the scale, but then not only is a quite considerable thickness required in order to obey the specification of the preceding paragraph, but also another phenomenon manifests itself and requires attention-Le. a pull of the magnet on the reed which, although the reed is still opposite the magnet to be pulled, diminishes at the extreme swings of the reed because of the arcuate nature of the locus of the reeds free end. This phenomenon will result (just as would an appreciable overshooting of the magnet by the reed) in a shifting effect on thereeds vibrational frequency as between highand low-amplitude vibration, and is quite intolerable. Accordingly when it is desired to utilize the separate magnet for a lower-frequency reed it is desirable not onlyto make it sufficiently thick, but also to make its reed-facing surface arcuate and substantially equispaced from the free end of the reed as the reed vibrates. This has been illustrated in FIGURE 7, for a reed R not itself containing any magnet but otherwise of a length corresponding to that of iced R (shown in FIGURE 4), by the magnet M which obeys the specifications of the preceding sentence.

There is an alternative, to both the magnet comprised in the reed and the separate magnet, which may be employed at any or all regions of the scale; this comprises a reed of magetizable material magnetized to itself constitute the field-creating means. I have found, however, that it is desirable to embody this in a particular manner, lest the hardness which is requisite for good magnetic retentivity result in too great brittleness of the reed at and near its fixed extremity and in consequent propensity to reed breakage there. According to this manner I form the reed of a material such as a relatively hard cobalt steel (e.g. having a Rockwell hardness of about 65 RC); I anneal the fixed-end approximate half of the reed, but leave the other or free-end half at its normal hardness magnetizing (longitudinally) the latter half only. FIG- URE 8 illustrates as R a reed (otherwise similar to the reed R of FIGURE 7) treated in this manner.

In connection with the introduction of multiple-frequency components into the translated oscillations, I have observed that this is enhanced, especially in the middle and higher portions of the scale, by reducing the thickness of the conductor 30 or 40 (or both when employed) and, when magnets form the free-end portions of the reed, the free-end thickness of those magnets, and that best results are achieved by making such thickness reductions progressive with increasing frequency. Accordingly in FIGURES 2 through 6 it will be seen that the thicknesses of the

conductors

30 and 40 have been progressively reduced, and in FIGURES 2 through 4 that the reed-contained magnets have been progressively bevelled to result 9 in a progressive reduction of their free-end thicknesses (the enlarged FIGURES 3a and 4a facilitating an observation of the latter).

It is also to be observed that when the

conductors

30 and 40 are jointly used it is desirable progressively to reduce the inter-center spacings of those conductors with progressively higher reed frequency. This technique, illustrated in FIGURES 2 through 6, is of course facilitated by the progressive reductions of the thicknesses of those conductors, just mentioned.

Each loop which is employed is provided with output means responsive to the current generated in that loop by the vibrating reeds. Accordingly each of the transformers 33 and 43 has been shown as provided with a many-turn secondary (32 or 42), which constitute such means for the respective loops.

Attention may now be turned to the joint use of the two

conductors

30 and 40. It has already been pointed out that the conductor 30, aligned with the rest positions of the reeds, will not introduce any even-numbered multiplefrequency components into the translated oscillations; on the other hand the conductor 40, being substantially displaced from such alignment, will tend to introduce a very ample, if not excessive, quantity of such components. Advantage may be taken of these opposite characteristics, for such purposes as relatively precise predetermination of the general balance between evenand odd-numbered multiple-frequency components or deliberate variation from time to time of that balance for special tonal effects, by the joint use of the two conductors together with means for combining the oscillation outputs therefrom in one or another selected relationship. To provide such means the

secondaries

32 and 42 may be connected across respective potentiometers 34 and 44 which may have respective fixed center-taps 35 and connected together, and which have respective variable contacts 36 and 46 (each for example movable over the whole potentiometer); these variable contacts may form the output terminals of the translating system, across which terminals will appear oscillations from each of the two translating means combined in a relationship selectedboth as to amplitude and as to phase-by the adjustments of the

contacts

36 and 46. From these terminals (or directly from the transformer secondary if only one of the translating means and thus one transformer be employed) the oscillations may typically be applied to the input of an electronic amplifier 50, whose amplified output in turn feeds a loudspeaker or other electro-acoustic translating device 51.

It will be appreciated that when both the

conductors

30 and 40 are employed, together with such means as the potentiometers 34 and 44, there are associated with each reed two translating means each of the type which translates from the reed vibrations electric oscillations comprising wavefronts of respectively opposite polarities in response to the oppositely directed higher-amplitude sweeps of the reed, and that the reed-influenced portions of those two means are spaced from each other in the direction of reed vibration. From another point of view there are then associated with each reed two translating means each bidirectionally swept past by the reed in each cycle of-its higher-amplitude vibration but of which at least one is not swept past during useful lower-amplitude vibrations of the reed. The structure according to either of the two preceding sentences I have found of great value, in a decadent-tone instrument such as an electronic piano, for such purposes as dealt with in the preceding paragraph.

Attention may be re-directed to the reed-exciting action shown in FIGURE 2 and briefly described above as being provided for each of the several reeds. In it there may be incorporated techniques broadly similar to those disclosed in Patent No. 2,271,460 heretofore issued on an application of mine, including in particular the partial filling of the hollow cylindrical hammer head 11 with individual solid particles 13for which I have now found metallic shot to be an excellent choice. Upon depression of the front end of the key 20 the hammer 10 will be propelled upwardly toward the reed; this propulsion will go on until the rear end of the key has been brought upwardly into impingement against the adjustable up-stop 23, at which time the hammer head 11 and its reed-striking pad will have been brought upwardly to such a position as is indicated in either of FIGURES 4 and 6. Further propulsion of the hammer and the shot 13 contained in the head 11 is then terminated, but both will move on under the influence of momentum so that the pad 12 strikes the reed; there is then foreclosed further upward movement of the head 11, which instead rebounds downwardly, but the contained shot 13 may and does continue to move upwardly-the shot impinging against the upper-end inner surface of the rebounding head 11 and largely neutralizing or absorbing the energy of its rebound. Furthermore when the butt 18 of the rebounding hammer impinges on the top of the still-raised capstan 21, at which time it and the hammer tend to execute a re-bound, the shot 13, still elevated within the head 11, flies on downwardly into impingement against the lower-end inner surface of the head and neutralizes or absorbs the energy of the re-rebound.

In the present structure the hammer head is propelled at many times as great a velocity as in the disclosure of the patent, and I have found that problems arise in connection with the timing or phasing of the neutralizing or energy-absorbing impacts of the shot against the end inner surfaces of the head 11 (particularly the upper inner surface). These problems I have found it possible to solve by progressively reducing the stroke' of the shot 13 for progressively higher-frequency reeds (with which the speed of rebound of course becomes progressively greater). This I have illustrated in FIGURES 4 and 6, taken in comparison with FIGURE 2. Thus in FIGURE 4 I show a plug 14 of moderate thickness underneath the shot 13 and serving to reduce the free length of the space within the hollow hammer head 11 of that figure, while in FIGURE 6 I show a plug 14" of substantially greater thickness in a similar position and serving to reduce still further the free length of the space within the hollow hammer head 11" of that figure.

In connection with the hammers I may point out another technique which I have found of value in setting the reeds into decadent vibration both efliciently and principally at their fundamental frequencies. This is the use of reed-contacting pads (typically of medium felt) which for the lowest-frequency reeds are of relatively substantial length longitudinally of the reed, but which are progressively reduced in such length for progressively higher-frequency reeds, as seen in the comparison of

pads

12, 12' and 12" in FIGURES 2, 4 and 6 respectively. This technique may be supplemented by that of some progressive diminution of thickness of those pads, also illustrated in those figures.

An electronic piano with the translating means above disclosed may be voiced, or adjusted for proper relative tone amplitudes from its several reeds when correspondingly excited, by adjustment of the separation between the conductor or conductors (30 and/or 40) and the vibrational locus of the end of each reed-it being understood that maximum tone amplitude from any reed for a given vibratory amplitude of that reed is achieved with the closest possible such spacing which does not interfere with the reed vibration. (This spacing also has some effect on the degree of introduction of multiple-frequency components into the translated oscillations, and in order not unnecessarily to reduce that degree excessive spacings should be avoided.) Voicing in the manner just indicated can readily be employed to adjust out or eliminate any breaks in the tone amplitudes as between successive reeds which are provided with quantitatively or qualitatively ditferent field-creating means (such as the successive reeds R -R or R -R or R R It may be pointed out that in the figures the separation discussed in the preceding paragraph has been exaggerated in order clearly to show the separate parts; ordinarily it will be of the order of a few thousandths of an inch only. Thus the relationship of the conductor or conductors 30 and/or 40 to the reeds free edge portion (e.g. end) is one of close adjacency; it is also one of immediate adjacency-Le. there is no object intervening between the conductor or conductors and the reeds free edge portion.

In the layout according to FIGURE 1 there is a necessity to angle the

conductors

30 and 40 between successive reeds. To avoid such a necessity, at least within each one of the several frames, recourse may be had to the slightly modified layout of FIGURE 9. Herein each of the four frames 1, 1a, 1b and has been replaced by a frame (61, 61a, 61b or 610) modified as by rocking the quardilateral representing its outline, so as to increase two and decrease two of its four angles-so that the free ends of the reeds within that frame lie in a straight line which is at right angles to each of those reeds. The several frames are in turn so related to each other that the line L of striking of the several reeds by their hammers is a straight one across the entire instrument, which results in some (but very slight) tie-alignments as between the four lines respectively formed by the reed ends in the four frames. In FIGURE 9 the vertical legs or portions of the four frames are designated as 62, 62a, 62b and 620, and the horizontal portions as 63, 63a, 63b and 63c, respectively. For simplicity of the figure only a limited number of reeds are shown, with little detail, and the magnets and conductors have been omitted.

While I have disclosed my invention in terms of particular embodiments thereof it will be understood that I thereby intend no unnecessary limitations. Modifications in many respects will be suggested by my disclosure to those skilled in the art, and such modifications will not necessarily constitute departures from the spirit of the invention or from its scope, which I undertake to define in the following claims.

I claim:

1. An electronic piano of the type wherein electric oscillations are translated from the decadent free vibration of a fixed-free reed and wherein multiple-frequency oscillation components harmonically related to that vibration are introduced in that translation into those oscillations, including in combination a fixed-free reed, means for setting the reed into decadent vibration in the direction of its thickness, and electric translating means, having a portion located adjacent to and influenced by a free edge portion of the reed and bidirectionally swept past by that edge portion in each cycle of the higher-amplitude vibration of the reed, for translating from the reed 'vibrations electric oscillations comprising wavefronts of respectively opposite polarities in response to the oppositely directed sweeps of the reed, whereby said oscillations are caused to contain components of the fundamental frequency of the reed vibration and odd-numbered multiples thereof, said translating-means portion being displaced from alignment with the rest position of the reed whereby to cause said oscillations also to contain components of even-numbered multiples of said fundamental frequency.

2. An electronic piano of the type wherein electric oscillations are translated from the decadent free vibration of a fixed-free reed and wherein multiple-frequency oscillation components harmonically related to that vibration are introduced in that translation into those oscillations, including in combination a fixed-free reed compris- :ing magnetic material and vibratable in the direction of its thickness, an electrical conductor passing along and in immediate adjacency to a free edge portion of the reed and bidirectionally swept past by that edge portion in each cycle of the higher-amplitude vibration of the reed means, creating in the immediate vicinity of said edge portion a magnetic field which when said conductor is swept past by the reed passes transversely through said conductor along the plane of the reed, an electrically conductive loop in which said conductor is serially included, and output means responsive to the current generated in the loop by the vibrating reed.

3. The subject matter claimed in claim 2 wherein said edge portion is the free end of the reed.

4. The subject matter claimed in claim 3 wherein the reed is of magnetic material and said field-creating means comprises a magnet disposed on the opposite side of said conductor from said free end of the reed.

5. The subject matter claimed in claim 4 wherein the surface of said magnet facing said free end of the reed is arcuate and substantially equispaced from said free end of the reed as the reed vibrates.

6. The subject matter claimed in claim 2 wherein said field-creating means is :a magnet forming the free-end portion only of the reed.

7. The subject matter claimed in claim 2 wherein the reed is of magnetizable material and is magnetized to itself said field-creating means.

-8. The subject matter claimed in claim 2 wherein the free-end portion of the reed is of magnetizable material and is relatively hard and is magnetized to constitute said field-creating means, and wherein the fixed-end portion of the reed is of relatively softer material.

9. The subject matter claimed in claim 2 further including a second electrical conductor, spaced from said firstrecited conductor in the direction in which the reed vibrates, also adjacent said free-edge portion and also bidirectionally swept past by that edge portion in each cycle of the higher-amplitude vibration of the reed, a second electrically conductive loop in which said second conductor is serially included, second output means responsive to the current generated in the second loop by the vibrating reed, and means connected with said two output means, for combining oscillations from each in a selected relationship.

10. An electronic piano of the type wherein electric oscillations are translated from the decadent free vibrations of fixed-free reeds and wherein multiple-frequency oscillation components harmonically related to those vibrations are introduced in that translation into those oscillations, including in combination a series of progressively tuned fixed-free reeds each comprising magnetic material and vibratable in the direction of its thickness, an electrical conductor passing along and in immediate adjacency to a free edge portion of each of the reeds and bidirectionally swept past by that edge portion of each reed in each cycle of the higher-amplitude vibration of that reed, means creating in the immediate vicinity of said edge portion of each reed a magnetic field which when said conductor is swept past by that reed passes transversely through said conductor along the plane of that reed, an electrically conductive loop in which said conductor is serially included, and output means responsive to the currents generated in the loop by the vibrating reeds.

11. The subject matter claimed in claim '10 wherein the thickness of said conductor is progressively diminished in its portions adjacent progressively higher-frequency reeds.

12. The subject matter claimed in claim 10 wherein said field-creating means for each reed of said series is a respective magnet forming the free-end portion of that reed, and wherein the free-end thicknesses of said magnets in progressively higher-frequency reeds are progressively diminished.

13. The subject matter claimed in claim 12 wherein the thickness of said conductor is progressively diminished in its portions adjacent progressively higher-frequency reeds.

14. An electronic piano of the type wherein electric oscillations are translated from the decadent free vibration of a fixed-free reed and wherein multiple-frequency oscillation components harmonically related to that vibration are introduced in that translation into those oscillations, including in combination a fixed-free reed, means for setting the reed into decadent vibration in the direction of its thickness, two electric translating means, each having a portion adjacent to and influenced by a free edge portion of the reed and 'bidirectionally swept past by that edge portion in each cycle of the higher-amplitude vibration of the reed, each for translating from the reed vibrations electric oscillations comprising wavefronts of respectively opposite polarities in response to the oppositely directed sweeps oft-he reed, said portions of said two translating means being spaced from each other in the direction of reed vibration, and means connected with said two translating means for combining oscillations from each in a selected relationship.

15. An electronic piano of the type wherein electric oscillations are translated from the decadent free vibration of a fixed-free reed and wherein multiple-frequency oscillation components harmonically related to that vibration are introduced in that translation into those oscillations, including in combination a fixed-free reed, means for setting the reed into decadent vibration in the direction of 20 its thickness, two electric translating means each having a portion adjacent to and influenced by a free edge portion of the reed and bidirectionally swept past by that edge portion in each cycle of the higher-amplitude vibration of the reed, said portions of said two translating means being spaced from each other in the direction of reed vibration and at least one of them being not swept past by said edge portion of the" reed during useful lower-amplitude vibration of the reed, and means connected with said two translating means for combining oscillations from each in a selected relationship.

References Cited by the Examiner UNITED STATES PATENTS 2,581,963 1/52 Langloys 841.15 X 2,704,957 3/55 Miessner 841.l5 2,881,651 4/59 Andersen 84- l.14 2,901,936 9/59 Scherer et al 841.14 X 2,948,178 8/ 60 Jacobson 84-1.04 3,038,363 6/62 Miessner 841.l4

ARTHUR GAUSS, Primary Examiner.

Claims

2. AN ELECTRONIC PIANO OF THE TYPE WHEREIN ELECTRIC OSCILLATIONS ARE TRANSLATED FROM THE DECADENT FREE VIBRATION OF A FIXED-FREE REED AND WHEREIN MULTIPLE-FREQUENCY OSCILLATIN COMPONENTS HARMONICALLY RELATED TO THAT VIBRATION ARE INTRODUCED IN THAT TRANSLATION INTO THOSE OSCILLATIONS, ICNLUDING IN COMBINATION OF FIXED-FREE REED COMPRISING MAGNETIC MATERIAL AND VIBRATABLE IN THE DIRECTION OF ITS THICKNESS, AN ELECTRICAL CONDUCTOR PASSING ALONG AND IN IMMEDIATE ADJACENCY TO A FREE EDGE PORTION OF THE REED AND BIDIRECTIONALLY SWEPT PAST BY THAT EDGE PORTION IN EACH CYCLE OF THE HIGHER-AMPLITUDE VIBRATION OF THE REED MEANS, CREATING IN THE IMMEDIATE VICINITY OF SAID EDGE PORTION A MAGNETIC FIELD WHICH WHEN SAID CONDUCTOR IS SWEPT PAST BY THE REED PASSAGES TRANSVERSELY THROUGH SAID CONDUCTOR ALONG THE PLANE OF THE REED, AN ELECTRICALLY CONDUCTIVE LOOP IN WHICH SAID CONDUCTOR IS SERIALLY INCLUDED, AND OUTPUT MEANS RESPONSIVE TO THE CURRENT GENERATED IN THE LOOP BY THE VIBRATING REED.