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Publication numberUS2530251 A
Publication typeGrant
Publication dateNov 14, 1950
Filing dateAug 9, 1945
Priority dateAug 9, 1945
Publication numberUS 2530251 A, US 2530251A, US-A-2530251, US2530251 A, US2530251A
InventorsLouis Luberoff
Original AssigneeLouis Luberoff
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Piano construction for sound amplification
US 2530251 A
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Description  (OCR text may contain errors)

L LUBEROFF Nov. 14, 1950 Filed Aug. 9, 1945 nunk Nov. 14,` 1950 LuBERoFF PIANO CONSTRUCTION FOR SOUND AMPLIFICATION 6 Sheets-Shet 2 Filed Aug. 9, 1945 Nov. 14, 1950 L. LUBEROFF 2,530,251

PIANO CONSTRUCTIN FOR SOUND AMPLIFICATION Filed Aug. 9, 1945 l 6 Sheets-Sheet 3 i F/Q.

Nov. 14, 1950 |m LUBEROFF PIANO CONSTRUCTION FOR SOUND AMPLIFICATION Filed Aug. 9, 1945 6 Sheets-Sheet 4 Nov. 14, 1950 l.. LUBEROFF 2,530,251

PIANO CONSTRUCTION FOR SOUND AMPLIFICATION Filed Aug. 9, 1945 6 Shets-Sheet 5 N O' @Miam/5f I z5 HW??? Lg www Nov. 14, 1950 L. LUBEROFF 2,530,251

PIANO CONSTRUCTION FOR SOUND AMPLIFICATION 6 Sheets-Sheet 6 Filed Aug. 9, 1945 ,57gl 7.. g 65 a 5 Patented Nov. 14, l9'50 UNITED STATES PATENT OFFICE PIANO CONSTRUCTION FOR SOUND AMPLIFICATION 3 Claims.

This invention relates to musical instruments, and more particularly toa novel piano-type instrument having the various characteristics and features hereinafter described.

One object of the invention is to provide a novel piano which has the appearance and tone quality of a grand piano, but which differs from the usual grand piano in that it has a vertical sounding board of relatively small dimensions.

Another object of the invention is to provide a high-quality piano-type instrument which may be manufactured at substantially lower cost and may be sold at a correspondingly lower price than a conventional grand piano having comparable tone quality.

A further object of the invention is to provide a piano having a vertical chamber in which is disposed a vertical sounding board, and also having a horizontal chamber and at least one air passage between the two chambers, whereby sounds generated by the sounding board are conveyed to the horizontal chamber for amplification by the latter.

Still another object of the invention is to provide such a piano which further includes means for electrically reproducing sounds from the vibrations of the sounding board, such means including a loud speaker within the horizontal chamber.

' A further object of the invention is to provide a multi-section sounding boardin 'such a piano. Other objects of the invention will become apparent as the description proceeds.

In the accompanying drawings, Fig. 1 is a pictorial perspective View of the \musical instrument provided by thepresent in,- vention, with the lid or cover raised; Fig. 2 is a planfview of the instrument wit the lid or cover removed to show the various mounting arrangement-employed according to l the invention; Y

Fig. 7 is an enlarged perspective view illustrate' ing one of the knee-operated volume control de`r vices employed according to the invention;

- Fig. 8 is an enlarged fragmentary"perspective` view showing the preferred form of the volume control devices;

Fig. 9 is an enlarged fragmentary sectional view of one of the knee-operated volume control levers, showing the mounting thereof; and

Fig. 10 is a diagrammatic illustration of the electrical system employed in the instrument, illustrating certain novel features thereof.

Referring first to Figs. 1 to 4, the musical instrument provided by the invention comprises a piano i and a tail section 2 removably attached together as will be described in further detail hereinafter. The piano I is a complete instrument in itself and comprises a keyboard 3, a vertical sounding board 4 (see Fig. 4), and keyactuated striking devices, one of which is shown in Fig. 4 and is designated generally by reference character 5. The various components are mounted within or on the piano casing which is designated generally by reference character 6, and which is provided with supporting legs 1. As may be seen in Figs. 1 and 4 the casing has a vertical rear portion 8 to accommodate the sounding board and the associated striking mechanisms. The sounding board is vertically disposed at the rear within the casing portion 8 which has a removable rear panel 8a, as shown in Fig. 3. The sounding board 4 is mounted in the customary manner, extending downwardly from the pin block 9, and has the usual supporting ribs I0 on its rear face or side, and the usual bridge I I on its front face. The strings I2 extend between the upper and lower pins I3 and I4 over the bridge I I. The piano section is also provided with the usual foot pedals I5, which perform their customary functions through suitable associated mechanism.

While the piano is of the vertical type, i. e. it has a vertical sounding board, its height is substantially the same as that,` of the usual grand piano. As clearly shown in Figs. l and 2, the tail section 2, which is removably attached to the piano section, has substantially the shape and dimensions of the tail section of the usual baby grand piano. Therefore, the instrument as a whole has the general appearancek of a grand piano.

Thertail section 2 is of shallow depth and large horizontal area, and'it extends rearwardly from e the kupper partfof the piano section, as shown inv Fig. 3'. The tail section comprises a Vertical for' ward wall"l6,'a curved wall Il joined to the forward'wall, a floor 18, Yand ahinged lid I9. I' 'The forward wall IG- is removablysecured tol the'pin blockl -9 "by 'means of'y suitable screws 2o, yand "isf also secured to the casing or housing structure of the piano section by additional screws 2l. The wall I6 has openings 22 therein through which sounds are conveyed from the sounding board 4 into the chamber formed by the hollow tail section. The latter serves as a sound-amplifying chamber as will be further described later. Thus, the portion 3 of the piano casing or housing constitutes a sound-generating chamber by reason of the presence of the sounding board therein, while the hollow tail section constitutes a sound-amplifying chamber which receives the generated sounds through the openings 22. The hollow tail section is supported at its rear by means of a supporting leg 23, which is removably secured to the tail section.

It will be noted that by virtue of the detachability of the piano section, the hollow tail section, and the rear supporting leg, the instrument may be readily moved or transported in secl tions.

As shown in Figs. 2 and 3, a rail 24 extends adjacent to the curved wall ll. The purpose of this rail is to strengthen the entire tail section and also to support certain components of the instrument as described hereinafter. The rail 24 is preferably formed of laminated material so as to increase its rigidity.

In order to produce sounds from the piano electronically as well as mechano-acoustically, a plurality of electrical pick-up devices 25 and 25a (see Fig. 3) are mounted on the rear face of the sounding board li. These pick-up devices are mounted in a special manner, as will be described later. In the specific illustration, two pick-up devices are employed and are located so as to respond to vibrations in the low and high frequency portions of the operating frequency range. The pick-up devices (see Fig. 6) preferably take the form of conventional electro-magnetic pick-ups comprising an electromagnet and a movable magnetic armature, but any other suitable type may be employed. A suitable pick-up is that manufactured and sold by Amperite Co. under the trade name of Kontak Mike. The pick-ups serve to generate electrical currents which are supplied to electronic amplifying devices mounted within the hollow tail section. As described hereinafter, the pick-ups are preferably mounted on dilferent sections of the sounding board for response to different frequencies.

Referring to the components or devices disposed within the hollow tail section, an audio frequency amplifier 25 (see Fig. 2) is mounted on suitable supports 2l and 38 carried by the supporting rail 2li and an auxiliary rail 29. A radio receiver is also mounted on the said supports. A phonograph 3l and recorder 32 are mounted on a platform 33 (see Fig. 3). A loud speaker 34 is mounted on the iioor !8 which serves as a baille and which is free of the other devices mounted Within the hollow casing. A grill 35 serves to cover the loud speaker and the amplifier 26 as may be seen in Fig. l, and a second grill 36 serves to cover the radio receiver The electrical connections of the various devices will be described later.

The vertical panel 31 (see Figs. 1 and 4) at the front of the piano section l and immediately adjacent the keyboard 3 is made to serve as a control panel on which various control elements are mounted. At the extreme left-hand end of this panel (Fig. 1) there is provided a rotatable knob 38 which is connected by means of a flexible cable 39 (Fig. 2) to the tuning condenser gang 40 of the radio receiver 30. Adjacent to the `knob 38 of the person playing the piano.

there are provided a plurality of push buttons 4l and an associated tuner 42 which is electrically connected to the radio receiver and provides for remote push button tuning. Adjacent the push buttons there are a plurality of knobs designated generally by reference character 43, and at the right-hand side of the control panel there are other control knobs designated generally by reference character 44. These various knobs are employed to effect switching and volume control operations, which will be described hereinafter. Finally there is provided a control knob 45 which enables micro-tuning of the phonograph speed control mechanism 46 (Fig. 2) by means of a shaft 41 and suitable gearing 48. The shaft 4l extends through an opening in the pin block 9, as may be seen in Fig. 3. The specific purpose of this phonograph tuning control will be described later. Thus it will be seen that all the Various hand controls are within easy reach of a person seated in the piano playing position.

In addition to the above-mentioned hand controls there are also provided two levers 49 and 50 (see Fig. l) which are operable by the knees These knee control levers are adapted to operate volume control devices so as to control the volume of sounds reproduced by the loud speaker 34 during the playing of the piano either alone or in conjunction with the radio or phonograph. Figs. '7 to 9 illustrate the left knee control lever and the associated volume control device, it being understood that the knee control mechanisms are similar, being arranged for actuation in opposite directions. As shown in Fig. 9 each knee control lever is pivotally mounted at the underside of the key bed 5| (see Fig. 4), which also serves to support the piano keys. A suitable mounting arrangement is shown in Fig. 9, wherein an inner cylindrical member 52 is iixedly secured to the panel 5l, and an outer cylindrical member 53 is secured to the lever 49. The lower end of the cylindrical member 53 is closed by a disc 54 which is interlocked with the cylindrical member 53. A bolt 55 is supported within the hollow cylindrical structure, and a helical spring 56 encircles the bolt and has its ends anchored at 57 and 58 to the relatively movable parts of the hollow cylindrical structure. The lever 49 carries a gear sector 59 which is arcuately slotted at 6D to accommodate a stop pin 5| mounted on panel 5l. Thus the stop pin and the associated slot SU serve to limit the range of rotary movement of the gear sector about the pivot axis of the lever 49. The spring `56 serves to maintain the lever normally in the position for minimum volume.

The teeth 62 on gear sector 59 mesh with a pinion t3 mounted on the rotatable shaft of the associated volume control device 64. The latter is also secured to the panel 5|, as shown in Fig. 4 by means of screws 65. Preferably the volume adjustment is effected in steps or increments, and to this end the volume control device has a plurality of stationary contacts 66 (see Fig 8) which are engaged by a wiping contact arm 6T carried by the rotatable shaft 68.

Mention has been made previously that at least two pick-up devices are employed, one for the lowY frequency or bass notes, and the other for the high frequency or treble notes. Fig. 5 shows the rear face of the sounding board with the pick-up devices attached thereto. In accordance with a further feature of the invention, a division of the bass and treble sections 'I0 and Il s effected by splitting the sounding board 4 and/,or the bridge I I. Preferably both the sounding board and the bridge are split, as shown at 69. In the illustration, the split 69 does not extend the full height of the board, but it may do so if desired. The purpose of this feature is to prevent the bass and treble overtones from running together objection-ably when the loud sustaining pedal is used and the piano is being played electronically. This objection is very pronounced in the ordinary electronic piano. By dividing the sounding board and/or the bridgeinto sections, I have found that the running together of the treble and bass overtones can be controlled or substantially eliminated. Contrary to the prevailing notion that splitting the sounding board and/or the bridge of a piano will deleteriously aect its tone quality, I have found that the splitting of the board enhances the tone quality of an electric piano employing pick-ups on the sounding board.

As previously mentioned, I prefer to employ a certain method of attaching the pick-up devicesv to the sounding board. In any electronic piano employing one or more pick-up devices attached to thesounding board, it is very important that each pick-up shall remain in a fixed position and shall be maintained at all times in iirm engagement with the board. This has been difficult of achievement owing to the fact that the sounding board tends to swell or move with changes in weather and climatic conditions and with Variations in temperature. In accordance with the present disclosure, this diiculty is overcome by attaching each pick-up device to the sounding board by means of an adhesive material, consisting of rubber, a resin derived from gum or wood rosin, a filler such as zinc oxide, and a softener such as lanolin. As shown in Figs. 5 and 6, each pick-up device is secured to the sounding board by placing the adhesive material 12 about and over the pick-up device and over a substantial area of the sounding board. I have found that this adhesive material becomes hardened and effectively becomes a part of the sounding board, which is due to a chemical reaction between the shellac or other coating on the sounding board and the chemicals with which the adhesive material is treated. This method of attaching the pick-up devices is very effective in providing permanent xation of said devices despite any swelling or moving of the board that may takel place.

Reference may now be had to Fig. `which is a diagrammatic illustration of the electric system embodied in the instrument. In addition to the aforementioned devices, the system includes a microphone 13 and a recording meter 14, these devices being shown in Fig. I. The radio receiver hereinbefore mentioned is of conventional form, and for convenience its components are represented in Fig. 10 by the blocks of rectangles 30a and 38h'. The block 38a represents the radio frequency and detector stages, while the block 38D represents the audio amplifier section of the receiver. The phonograph 3l, hereinbefore mentioned, is also of conventional form and is represented by a block or rectangle. The same is true of the amplifier 26' and the recorder 32. The necessary power for operating the various devices is supplied in accordance with'conventional vpractice, and for convenience n the power supply is represented in Fig. 10 by means of the rectangle 15, The diagram of Fig. l0 is a simplified single line diagram of the various electrical connections.

The various switches shown and the various p6- tentiometers are controlled by means of the knobs 43 and 44 hereinbefore mentioned.

The pick-ups 25 and 25a are connected to a double-throw switch 16, as is also the microphone 13. The pick-ups are preferably connected to the switch through individual potentiometers or voltage dividers 11 and 11a, by means of which the outputs of the pick-ups may be relatively varied. Thus the amplitude of the electrical signal derived from each section of the sounding board may be controlled as desired. By means of the switch 16, either the pick-ups or the microphone may be connected to the pre-amplifier 26, which in turn may be connected to the audio amplifier 30h through the ganged double-throw switches 18 and 19. The left-hand knee-operated volume control device, hereinbefore described, is shown at 64, and an associated hand-operated Volume control device is shown at 80. By means of the ganged switches 18 and 19, either of these volume control devices may be rendered operative, re-v gardless of the position of the hand-operated volume control device 80.

The phonograph 3| and the portion 30a of the radio receiver are connected to a doublethrow switch 8l, by means of which either of the said devices may be connected to the audio amplifier 38h through the ganged switches 82` and 83. The latter serve to control the righthand knee-operated volume control device 84 and the associated hand-operated volume control device 85. That is to say, by means of the ganged switches 82 and 83, either of the said volumeL control devices may be rendered operative, regardless of the previous position of either volume control device.

The output of the audio amplifier 30h may be supplied to either the loud speaker 34 or the recorder 32 by means of ganged double-throw switches 86 and 81 (or a double-pole doublethrow switch). The connections to the recorder may include a transformer 88. The recording meter 14 may be connected across the secondary winding of the transformer, as shown. In accordance with a further feature of the invention, provision is made for using the loud speaker 34 as an audible indicator during recording. To this end, there are provided resistors 89 and 90 connected to the switches 86 and 81 in the manner illustrated. When the switches are in the upper manner to reproduce sounds emanating from one or more of the various devices employed in the instrument. When the switches 86 and 81 are in the lower positions, the recorder is connected to the audio amplifier 30D, and the loud speaker is also connected to the amplier through the resistors 89 and 90. The values of these resistors are such that they permit a small percentage, preferably about 5%, of the sound currents to pass into the loud speaker, which thus serves as an audible indicating device and enables the operator to tell when the recording should be started and stopped. volume of sound emanating from the loud speaker is insufficient to cause mechanical feedback to the recorder. volume control devices and the recording meter 14, enables the operator to control the recording any sound recording operation, the amplitude of At the same time, the

This feature, together with the 7 thesoundsgnals must be accurately controlled to prevent under-cutting or over-cutting of the sound grooves in the recording disc, and this necessitates proper variation of the amplitude throughout the recording operation. The necessary accurate control is enabled by means of the arrangement provided by the present invention.

The power supply unit 'l5 is energized-by means of the main power switch el, and it supplies the necessary power and voltages to the various devices through the connections S2, 93, 94- and S5, Switches 9E and Si serve to control the operation of the radio receiver and the phonograph respectively.

Referring new to the operation of the musical instrument, it may be assumed rst that it is desired to play the piano by itself and not as an accompanimentto any of the other devices. In such case, the switches 96 and Gl will be opened. The piano may be operated with or without the operation of its associated electronic system. I the latter case, the main power switch SI1 will be opened. The casing or enclosure formed by the hollow tail section 2 serves as asound-receiving chamber and it functions in the manner of a megaphone to amplify the sounds emitted by the sounding board. The casing or enclosure thus functions as an acoustic amplifier and it also functions as a box-type baffle for the loud speaker 34. The acoustic output of the loud speaker is very substantially increased by reason of its being disposed within the said enclosure. Further, the shape of the enclosure, and the location of the speaker adjacent the rear curved wall thereof, contribute greatly to the effects produced.

Usually it will be desired to utilize the electronic system associated with the piano in order to obtain the improved tone quality resulting therefrom. In such case, the main power switch 9i will be closed, and the switch 75 will be closed in its upper position to connect the pick-ups and 25a to the preamplifier 26. The switches 8S and 8'! will also be closed in their upper position to connect the loud speaker directly to the amplifier 36h. The switches 'i3 and i@ may be closed in either position, depending upon whether or not it is desired to use the knee-operated volume control device 6G. With the electronic system in operation, the piano operates both mechano-acoustically and electronically. Although the piano itself it relatively small, the

instrument as a whole is comparable to a high quality concert grand piano from the standpoint of both volume and tonal quality. rhis has been demonstrated by an instrument constructed as illustrated and described herein.

The selective knee-hand volume control arrangement is a highly desirable feature. If it is desired to play the piano electronically without electrical variation of the volume, the ganged switches 'I8 and le may be adjusted to their right-hand position merely by turning one of the control knobs on the control panel, and the volume control device B may be set to a desired volume level merely by adjusting another of the control knobs. If it should be desired to vary the volume electrically during the playing of the piano, the ganged switches 'i8 and 19 may be thrown to their left-hand position simply by turning the appropriate control knob. Thereafter the volume may be controlled by actuating the left knee lever so as to produce any desired volume variation. Moreover, the pianist may switch from hand volume control to knee volume to the desired volume level.

control', or vice versa, during the playing of a'- selection, since this merely requires the turning of a single control knob, which can be done very quickly and without interrupting the playing ofl thev piano selection.

Whenever desired, the piano may be played as an-accompaniment to either the radio or the phonograph, simply by closing one or the other of the switches 96 and 91 and by properly positioning the switch 8l. In such case, the volume of the radio or phonograph reproduction may be set at a desired level, by throwing the switches 82A and 83 to their right-hand position and by setting handV volume control device 85 according If desired, however, the volume level of radio or phonograph reproduction may be varied by means of the knee-operated volume control device 84, merely by throwing the switches 82 and 83 to their left-hand position. Thus it is possible for one. to play the piano as an accompaniment to either the radio or phonograph, and at the same time vary the respective volume levels of the piano and the accompanying instrument by operating the right and left knee control levers. It is possible in this way to obtain desirable and artistic musical interpretation.

When it is desired to play the piano as an accompaniment to the phonograph, the latter may be tuned to they pitch of the piano by means of the knob d5. Rotation of this knob varies the speed of the. phonograph turntable and thus varies the pitch of the phonograph reproduction. Since the knob 45 is located within easy reach of the player, the phonograph may be easily adjusted to the same pitch as the piano by aural comparison while adjusting the said control knob. Since there is substantial resistance to the turning of knob 45, due to inherent friction in the actuating mechanism between the knob and the speed control mechanism 46, this tuning arrangement not only enables line exact tuning of the phonograph to the pitch of the piano while in playing position, but also serves to maintain the steady desired pitch or tone of the phonograph, preventing the latter from getting out of tune."

With respect to the piano and phonograph and the associated controls, the instrument has utility features which might not be apparent to the casual observer. There are now available recordings of piano concertos, and other compositions involving a piano part, in which the piano part is omitted so that it may be supplied as an accompaniment by the user. Such recordings, known as Add-a-Part records, are sold with printed music` showing the parts recorded and the part omitted. The volume control and phonograph tuning features of the present instrument especially adapt it for the use of such recordings in conjunction with the piano, since the pianist has absolute control of the reproduction bothA as to volume and pitch and he also has control of the piano volume.

Moreover, by virtue of the features above mentioned, the instrument may be used to advantage in the teaching or learning of piano. The piano pupil or student may practice with special recordings of the type above-mentioned whichV may be adapted for various degrees of advancement of the. pupil. In such case, the recording will serve as a musical metronone.

Whenever desired, the recorder 32 (Fig. 10) may be connected for recording by throwing the ganged switches 86 and 81 to their lower position. A recording may be made during the playing of any of the several instruments or devices individually or in combination, by proper positioning of the switches, as will be apparent from the foregoing description. In addition it is also possible to reproduce or record voice from the microphone 13 either alone or as an accompaniment to the radio or phonograph by proper positioning of the switches. During any recording operation, the knee-operated volume control devices may be utilized to advantage, as previous- 1y described.

It is important to note that recording of piano is effected directly from the sounding board by means of the pick-ups and the amplifier system. This is much more satisfactory than the conventional method of recording piano by means of a microphone, which has never been very ysatisfactory, especially since piano recording is most difilcult. The present invention provides a solution of this problem.

From the foregoing description, it will be seen that the invention provides a novel musical instrument which is fundamentally an electronic piano, but which combines various features that greatly extend its utility and make it an al1-pur pose instrument. It will be apparent, of course, that the invention is not limited to the various structural details but is susceptible to modification within the scope of the appended claims.

I claim:

1. A piano comprising a walled structure forming a vertical chamber, said structure having front and rear vertical walls of substantial width and height, and relatively narrow side walls extending between the front and rear walls, whereby the vertical chamber defined by said walls is of substantial width and height but is of relatively narrow dimension from front to rear, a vertical sounding board and associated vertical strings disposed within said chamber, a hammer mechanism also disposed within said chamber in cooperative relation with said strings, a key board extending forwardly from the front of said chamber at the upper part thereof and including keys operatively connected with said hammer mechanism, a second walled structure forming a horizontal chamber extending from the rear of said first chamber at the upper part thereof, Said horizontal chamber being f substantial horizontal area but of relatively small vertical dimension, supporting means for said second structure at the rear thereof, and at least one air passage between said vertical chamber and said horizontal chamber, whereby sounds generated by the sounding board in said vertical chamber are conveyed by said passage to said horizontal chamber for amplification by the latter.

2. A piano comprising a walled structure forming a vertical chamber, said structure having front and rear vertical Walls of substantial width and height, and relatively narrow side walls extending between the front and rear walls, whereby the vertical chamber defined by said walls is of substantial width and height but is of relatively narrow dimension from front to rear, a vertical sounding board and associated vertical strings disposed within said chamber, a hammer mechanism also disposed within said chamber in cooperative relation with said strings, a key board extending forwardly from the front of said charnber at the upper part thereof and including keys operatively connected with said hammer mechanism, a second walled structure forming a horizontal chamber extending from the rear of said first chamber at the upper part thereof, said horizontal chamber being of substantial horizontal area but of relatively small vertical dimension, supporting means for said second structure at the rear thereof, at least one air passage between said vertical chamber and said horizontal chamber, whereby sounds generated by the sounding board in said vertical chamber are conveyed by said passage to said horizontal chamber for amplification by the latter, and means for electrically reproducing sounds from the vibrations of the vertical sounding board, said last means including a loud speaker mounted within the horizontal chamber on a part of said second walled struc-` ture which acts as a baffle.

3. A piano according to claim 2, wherein the Vertical sounding board comprises a plurality of sections which are vibrational substantially independently of each other, each section covering a predetermined portion of the audio frequency range covered by the entire sounding board, and wherein individual Vpick-ups are provided on the respective sections of the sounding board.

LOUIS LUBEROFF.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,681,161 Baldwin Aug. 21, 1928 1,739,680 La Joie Dec. 17, 1929 1,915,177 Berghane June 20, 1933 2,001,722 Hammond, Jr May 21, 1935 2,078,385 Kato Apr. 27, 1937 2,200,718 Miessner May 14, 1940 2,219,539 Riechers Oct. 29, 1940 FOREIGN PATENTS Number Country Date 491,985 Great Britain of 1938 OTHER REFERENCES Pub., Radio-Craft for January 1939 (pages 398 and 433)

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2974555 *Mar 18, 1955Mar 14, 1961Wurlitzer CoElectronic piano
US3001431 *Sep 22, 1954Sep 26, 1961Wurlitzer CoMusical instrument system
US3070671 *Jul 1, 1959Dec 25, 1962Morch Hans HenrikCombined record player and gramophone amplifier
US3721148 *Nov 15, 1971Mar 20, 1973E GossPiano
US3969970 *Nov 8, 1974Jul 20, 1976Libbey-Owens-Ford CompanyTransparent grand piano tops
US4201895 *Jul 15, 1977May 6, 1980Hill Harold W JrPassive audio signal mixing apparatus
US4656913 *Jan 27, 1986Apr 14, 1987Nippon, Gakki Seizo, Kabushiki KaishaElectronic musical instrument with keyboard and cover
US7140588 *May 7, 2003Nov 28, 2006Yamaha CorporationBrace rotating mechanism
US7267316Nov 17, 2004Sep 11, 2007Yamaha CorporationBrace rotating mechanism
US7479591 *Aug 29, 2007Jan 20, 2009Wheeler Ray LMobile music entertainment systems
Classifications
U.S. Classification84/743, 84/744, 369/80, 84/170, 369/69, 984/367, 84/177, 84/192
International ClassificationG10H3/18, G10H3/00
Cooperative ClassificationG10H3/18
European ClassificationG10H3/18