US2542611A

US2542611A - Pickup for electric organs

Info

Publication number: US2542611A
Application number: US714334A
Authority: US
Inventors: Victor I Zuck
Original assignee: Wurlitzer Co
Current assignee: Wurlitzer Co
Priority date: 1946-12-05
Filing date: 1946-12-05
Publication date: 1951-02-20
Anticipated expiration: 1968-02-20

Description

Feb. 20, 1951 v. l. zUcK 2,542,611

PICKUP FOR ELECTRIC ORGANS Filed Deo. 5, 1946 2 Sheets-Sheet 1 INVENTR.

Feb. 20, 1951 v, ZUCK 2,542,611

PICKUP FOR ELECTRIC ORGANS Filed Dec.- 5, 1946 2 Sheets-Sheet 2 7a g/a, INVENTOR.

Patented Feb. 20,A 1,951

UNITED STATES PATENT OFFICE 2,542,611 p PICKUP FOR ELECTRIC oRGANs Victor I. Zuck, Kenmore, Y., assigner to The Rudolph Wurlitierr Company. f North Tonawanda, N. Y., a corporation of Ohio" Appucatiim December 5, 194e, serial. No. 714,334-

14 Claims. (C1. S11-1.14)'

The present invention pertains inl gene-ral to electric organs, andi in particular, to organs of the air-driven reed type employing capacitative pickup elements to translate the reed movements into corresponding electrical signals whichv are amplied and reproduced. by aloudspeaken n In general, the amplitude of vibration of thereeds in an organ of the type described is relativelysmall. Consequently, it is convenient to employ pickup elements in the form of small condenser plates disposed substantially parallel to the reeds. and located. a short distance therefrom es a satisfactory means for generating electrical signals inresponse to the vibration of thereeds. In the case of very low tones, however, the usual construction of the pickup elements has been found unsatisfactory because the relatively large amplitude of vibration of thev reeds tends to produce such abrupt and` erratic changesv in capacity throughout each cycle of vibration that the desired relation between reed movement and pickup voltage is impaired. Under such conditions the low tones present in a given gamut or stop of similarly produced notes are reproduced less faithfully than are ther higher tones, causing the low tones to bel out. of character with the' remainder of theI notes` in the selected stop.

It is an object of this invention to improve the design and construction of the capacitative pickup elements in a vibrating reed type' of electric organ in such manner as will greatly facilitate the production of notes having uniform tone' quality throughout' each selected sto-p'. To this end I provide stationary condenser plates of novel form whichare adapted to maintain the desired capacitativ'e relation. with their cooperating reeds notwithstanding the large amplitude of vibration. ofthe reeds in the-lower tones.

A further objectI is to provide an improved condenser plateI or shell of channel cross-section Within which. the: vibrating reed may swing. whereby the constrast betweensignal intensities at different portions of the cycle of vibration is kept within certain desired limits. Y s

A still further object is to provide improved. pickup means for a vibrating reed type of electric organ wherein the distribution of capacity between a vibrating reed-and its stationary condenser. plate may be conv.eniently adjusted by varying the shape of the-Y'plate,Y thereby toY vary the tone quality of the note produced.

The above and other objects, features and advantages of the invention will be apparent from a study ofthe following specification, when taken inoonjunction `with the accompanying drawings, wherein:

f 2 Fig. 1 is a partial side elevational view of an airdrivenreedtype electric organl to which the principles of the present invention are applicable; n' s u o Fig.v 2 is an enlarged transverse sectional view o f the wind chest and reed frame of the organ shown i-n Fig. 1-; o Y o l, Fig; 3 is a perspectiveview of one of a number ofblocks of reedcells which are included in the reedf-rame; V Fig. 4 is a transverse sectional View' vof aoreed cellill-ustrati-ng details of the capacitative pickup elements whichnaredisposed therein; o V y .s Fig.Y 5 is a fragmentary sectional view taken along thevline 5--5 of Fig. 4; v Y o s Fig-6 is a transverse sectional view of a reed cell equipped with a niodied pickup arrangement; and l Fig. 'l is a Vfragmentary sectional view taken alongthe line 1 1 in Fig. 6. s

The electricA organ l0 shown in Fig. 1 comf prises one or morev keyboards l2, a` pedal board I4 anda set of stop' tablets I6; The keys and pedals of the organ are mechanically connected to* groupsof multi-contact electrical switches-,or coupler board assemblies, -Iiiv extending length- Wise ofthe organ rearwardly of the keyboard and pedal board. The coupler board assemblies I8- are interconnected with the stop tablets in such manner as to energize pallet operating magnets, disposed within a wind chest-2Min accordance withthe joint operation of the stop tablets and the organkeys or pedals. The pallets opera-tedby the magnets control the flow of air from the wind chest 2e to the reeds, which are disposedwithin areedframe 2-2. The wind chest 20- is continuously supplied with compressed air from a compressor 24 during operation of the organ. Thev reeds disposed in the reed frame 22 each have acapacitative pickup element associated therewith, which elements are connected toA the input circuit of al thermionicl amplifier 26 so as to deliver electric signals Ythereto corresponding to the reed vibrations; They output circuit of the amplie'r 2t is connected to a loii'dspeaker (not shown), which converts the elc'- tricalnsignals into audibletones'. w lReferring now more in particular to FigsIwZ through 5,. the wind chest 20` and reed frame 2`2` are separatedA by a pallet board 28 having" h'rizontalV rows of openings 30` extending therethrough. rieedrblocks 32. are" alignedswitn the horizontal rows of openings in tlie pallet board 2li", each` of the reedu blocksvv having a row 'ffree'd cells 3'4 formed therein'andT respectively aligned with the .openings 30'. The pallet board openings 36 normally are closed by pallets 36 which are attached to the armatures o1"- pallet magnets 38.

Whenever one of the pallet magnets is energized, through the joint operation of a stop tablet and an organ key, it attracts its armature to uncover its associated opening or port 30. Air then flows from the wind chest 20 into the reed cell 34 which corresponds to the operated stop tablet and organ key. The air thus admitted to the selected reed cell 34 fiows out through an opening 40 in a reed board 42 and thence through an acoustically lined passage 44 extending lengthwise of the organ to an exit port (not shown). In its passage through the reed cell 34 and opening 40, the air passes over a reed 46, causing it to be set into vibration. The vibration of the reed 46 produces a Variation in capacity between the reed and a pickup element 48 mounted in the reed cell 34, this effect being then utilized to produce electrical signals which are fed to the amplifier 26 of the organ.

'I'he construction of the capacitative pickup elements and the reed cells in which they are disposed is shown in detail in Figs. 4 and 5. The reed cells 34 may be formed by cutting a row of transverse grooves in a wooden member 50, which extends lengthwise of the organ and is glued or otherwise secured to the pallet board 28 with the aforesaid grooves in alignment with the openings 3U in the pallet board. The lower surface of the wooden member 56 is glued or otherwise secured to the reed board 42, with the aforesaid grooves in the member 50 aligned with the openings 40 provided in the reed board. The reed board'42 may be recessed into the pallet board 28, as shown, for added rigidity. The reed board 42 is adapted to receive the reed pouches which carry the reeds 46. A mute strip 52 is secured to the member 50 in any preferred manner so as to close the reed cells 34 formed therein and to hold the reed pouches firmly in place. The mute strip 52, being in contact with the pickup elements, is formed of Suitable insulating material such as plastic.

For the sake of compactness and economy, the

reed blocks 32 preferably are arranged in vertically stacked pars, Fig. 2, with the lowermost reed block of each pair disposed in inverted position. Wooden strips 55 extend lengthwise of and are glued or otherwise secured to the reed boards 42 of each pair of reed blocks 32 to form exhaust passages 44, each of which is common to a pair of reed blocks. The exhaust passages 44 are lined with sound-absorbing material 45 to absorb'the acoustical energy in the exhaust air. A baille board 54, Figs. 2 and 4, is provided between each pair of reed blocks 32 to avoid interference between the reeds included therein. The baille boards 54 are provided with transversely extending grooves 56, Fig. 5, in their upper and lower surfaces, which grooves form passages for conveying air from the openings 48 in the reed boards 42 to the exhaust passages 44. f

Each of the reeds 46 comprises an elongated vibratory element which is anchored at one end thereof as by being riveted to the reed frame or pouch 5I. In accordance with common practice the reeds 46 are electrically conductive in order that each reed may be employed as one element of a condenser, and hence the reeds usually are made of metal such as brass. These reeds 46 are electrically connected to a suitable source of potential through the reed pouches 5l, which also are conductive, and through metallic strips 64, the latter extending lengthwise of the reed boards' 4, 42 and being provided with contact arms to engage the undersides of the reed pouches 5I at the heel ends thereof.

The capacitative pickup elements 48 comprise channel-like members, or shells, which are formed of sheet metal, preferably phosphor bronze suitably plated to prevent corrosion, and which constitute stationary condenser plates for cooperation with the movable condenser plates afforded by the reeds 46. Each of the shells 48 includes a rectangular web or body portion 66 and a pair of flanges 68 extending normally thereto along the longer sides thereof. The flanges 68 are spaced apart a distance slightly greater than the width of the cooperating reed 46. The pickup shells 48 are positioned in the reed cells 34 in alignment with the reeds with which they are associated and with the edges of the flanges 68 disposed in close proximity to and extending along the edges of the reeds 46, whereby the reeds are enabled to vibrate between the flanges 68 without interference.

The shells 48 are biased toward the reeds 46 by bowed leaf springs 16, which are attached to the web portions 66 by rivets l2 and bear against the ceilings of the reed cells 34. To insure adequate insulation such as might not be afforded by the Wooden member alone, non-conductive strips 14 of insulating material such as plastic are disposed within the reed cells 34 between the pickup elements and the member 58. The insulating strips 14 are formed over at one end and extend through notches provided along one edge of the member 50 for a purpose to be described hereinafter.

The pickup shells 48 are supported by adjusting screws 16 each of which is provided with a head 11 that is attached to the shell 48 by soldering or the like. The screws 16 extend through clearance openings in the leaf springs 10, the insulating strips 14, the member 58, and a second insulating strip I8 covering the outer surface of the member 50. Adjusting nuts 88 threaded on the exposed portions of the screws 16 bear against lock washers 8| which are seated on the strip 18. This arrangement enables the position of each pickup shell 48 to be adjusted individually relative to its reed 46.

The pickup elements are supported also by resilient metal strips 82, which are secured thereto between the leaf springs 'I0 and the web portions 66 by the rivets 12. These metal strips 82 vextend over the insulating strips 14 and through the notches provided in the edge of member 50, thence extending over the insulating strip 18 to which they are secured by screws 84 that are threaded into the insulating strip. The strips 82 are employed to connect the pickup elements to the amplifier circuit 26 through a bus bar 86 (Fig. 3) which may consist of a plurality of links, each extending between an adjacent pair of the screws 84. It will be understood that Fig. 3 depicts only a few of the terminal screws 84 and adjusting screws 16 that actually are mounted on a reed block 32.

The form of pickup element herein shown and described enables a considerable variation to be obtained in the characteristics of the electrical signals which are produced in response to Vibra-r tions of the reeds. Thus, the shapes of the flanges 68 are important in determining the waveform of the electrical signal which is generated through a variation of the capacity between each pickup shell 48 and its reed 46.

These flange portions may be shaped in a variety even-harmonic distortion.

of forms such as indicated by broken lines in Fig". 4 to determine the'tone qualityv of the reproduced musical note in accord-ance with the character of the organ stop to which the note corresponds. The quality of the tone also may be regulated to some extent by rotating the adjusting nut 8B to move the pickupr shell d8 closer to or farther from the reed. Further variations of4 tone quality may be obtained by forming the strip' 82 supporting 'the pickupv shell 48 near the fixed end of the reed. These additional adjustments will aiford a small variation of tone duality' toY compensate for manufacturing variations.l

One of the advantages of my invention isthat it enables tones of uniform quality to bev reproduced from all of the vibrating reeds in each organ stop. It also enables tones of predetermined quality to be obtainedV simply by shaping a stationary condenser plate in lieu of more complicated methods heretofore regarded as necessary. The difficulty which formerly attended the production of satisfactory low tones in the vibrating reed type of electric organ is hereby eliminated. The invention further serves to increase the number of tone combinations which can be made available in the design of the orden.

A modied fornrof the invention wherein each reed cooperates with a pair of oppositely arranged pickup shells for the purpose of further reducing tone distortion is illustrated in Figs. 6 and 7. The reed block 32d, shown in these views, is constructed in a manner very similar to the block.. 32 described hereinabove. There'- fore, similar reference characters distinauished by the suffix letter a have been employed to denote corresponding parts in the second embodiment of the invention. Two pickup shells ifa are symmetrically located with respect to each of the reeds lita. These pickup shells are formed in the same manner as the pickup shells is in u Fig. 4 and are mounted in the reed cells 34a in a manner similar to that heretofore described. The baille board 511 and the resilient strips 82 of Figs. 4 and 5 have been omitted in the ern bodiment of Figs. 6 and '2. Pins 88, each of which anchors a leaf sprintf 'ma at one end thereof to a wooden member 5ta, serve to maintain the pickup shells 48a in alignment with the reeds 46a.; also, in Fig. 6, the bug bars 86a are electr-h cally connected to the pickup shells 48a through the screws 75d, thereby eliminating the need for the resilient stripsl 82 of Fia. 4. Thus, it is not necessary to notch an edge of each wooden member 50a, and the mute strip 52a may be formed of a material such as wood which is cheaper or more convenient to use than materials such as plastic having better insulating properties.

Where a pair of pickup elements is associated with each reed, as illustrated in Figs. 6 and 7, the pickup elements may be coupled to the amplifier 26, Fig. l, through a push-pull type of input circuit. Such circuits are familiar to those skilled in the art and are employed to eliminate In the present instance, such an arrangement is effective to reduce the distortion which results from the discrepancy between the actual variation of capacity with reed movement as compared with a true linear relationship. rIhis enables a Wider tonal range to be covered, particularly in the lower tones, without sacrificing uniformity of timbre of all the notes included in a stop. As in the case of the embodiment shown in Figs. 4 and 5, the pickup shells 48a have flanges 58d that may be shaped to produce the desired tone 6. quality of the musical note which is reproduced from the vibrationof the reed.

While particular embodiments;A cf theinvention have been shown and described herein, other modifications obviously can be made, and therefore it is intended that the appended claims cover all such variations as come within theV true spirit and scope of the invention'. y

The invention is hereby claimed as follows:

1. In an electric' organ, a reed comprising a conductive strip secured at one end thereof, and a pickup element capacitatively coupled to said reed, said' element having a surface spaced from and lying substantially parallel to the reed and intersecting. a plane of vibration of said reed and a at surface disposed substantially parallel to the direction of vibration of said reed and positioned to one side thereof, said surfaces dis# posed at an angle less than a straight angle. A

2. In an electric organ, a reed comprising a conductive strip secured atone end thereof', and a pickup element capacitatively coupled to said reed, said element having a surface spaced from and lying substantially parallel to the reed and intersecting a plane of vibration of said reed and a pair of spaced flat surfaces each disposed substantially parallel to the direction of' vibration of said reed and positioned on either side thereof, said spaced surfaces disposed relative to said first named surface at an angleles's than a. straight angle.

3. In an electric organ, a reed comprising a conductive strip secured at one end thereof, and a channel-shaped pickup shell capacitatively coupled to said reed, saidA shell being positioned in alignment with said reed and with the direction of vibration thereof and having flanged p0rtions the edges of which are disposed in proximity to the edges of said reed.

4. In an electric organ, a conductive vibratory reed, and a pickup element capacitatively coupled to said reed, said element having a body portion the area of which overlaps the area of said reed and a ange portion angular thereto extending substantially parallel to the direction of vibration of said reed and adapted to be shaped for producing a predetermined tone quality in the musical note reproduced from vibration 'of said reed.

5. In an electric organ having an amplifier, a reed comprising a conductive strip secured at one end thereof, and a pair of pickup elements of channel shape capacitatively coupled to said reed and adapted to cooperate in feeding pickup signals to said amplifier.

6. In an electric organ, a reed comprising a conductive strip secured at one end thereof, and a pair of pickup elements formed of sheet material capacitetively coupled to said reed and lying on opposite sides thereof substantially in the direction of vibration of the reed, said elements having dat surfaces disposed substantially co-planar and parallel to the direction of vibration of said reed and positioned to one side thereof.

'7. In an electric organ, a reed comprising a conductive strip secured at one end thereof, and a pair of pickup shells capacitatively coupled to said reed, each of said shells including a pair of spaced flange portions disposed substantially parallel to the direction of Vibration of said reed and positioned on either side thereof, and a body portion joining said flange portions intermediate the ends thereof and substantially parallel to said reed.

`In an electric organ, a reed comprising a conductive strip secured at one end thereof, and a pair of channel-shaped pickup shells capacitatively coupled to said reed, said shells being symmetrically positioned relative to said reed on opposite sides thereof and each having anged portions located in proximity to the edges of the reed.

9. In an electric organ, a conductive vibratory reed, and a pair of channel-shaped pickup 1i shells capacitatively coupled in opposed relation to said reed, each of said shells being adapted to embrace said reed during a portion ol each cycle of vibration thereof.

10. Irran electric organ having an amplifier,

a pair of channel-like stationary condenser shells, means supporting said shells in opposed spaced relation, and a conductive vibrator-y reed mounted intermediate said shells and capacitatively coupled thereto, said shells being adapted to cooperate in feeding pickup signals to said amplifier and being shaped to produce a predetermined tone quality of the musical note reproduced from the vibration of said reed.

11. In an electric organ, a conductive vibratory reed, and a pair of pickup shells capacitatively coupled to and partially overlying said reed in mutually opposed relation thereto, each of said shells having a body portion and an angularly disposed flange portion extending substantially parallel to the direction of vibration of said reed and adapted to be shaped for producing a predetermined tone quality in the musical not-e reproduced from vibration of said reed.

12. In an electric organ, a reed comprising a conductive strip secured at one end thereof, and a pickup element capacitatively coupled to said reed, said element having a relatively flat body portion lying spaced from and substantially parallel to and co-extensve with the reed, and a relatively nat flange portion depending from one edge of the body portion and lying in a plane substantially parallel to the direction of vibration of said reed and positioned adjacent one edge thereof.

13. In an electric organ, a conduct-ive vibratory reed supported at one end of its longitudinal axis, and a pickup shell capacitatively coupled to said reed, said shell having a body portion spaced from and lying substantially parallel to the longitudinal axis of the reed, and flange portions ext-ending from the body portion and angularly disposed in respect thereto adapted to be shaped for producing a predetermined tone quality of the musical note reproduced from the'vibration of said reed.

14. In an electric organ, a conductive Vibratory reed supported at one end of its longitudinal axis, and a fianged pickup shell capacitatively coupled to said reed, said shell being channelshaped in transverse cross section, the longitudinal axes of the shell and reed being parallel, and the shell being arranged to embrace said reed during at least a portion of each cycle of vibration thereof.

VICTOR I. ZUCK.

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

UNITED sTATEs PATENTS Number Name Date 2,318,936 Fisher May 1l, 1943 2,368,842 Kealoha Feb. 6, 1945 2,462,531 Minshall Feb. 22, 1949 FOREIGN PATENTS Number Country Date 434,421 Great Britain Aug. 27, 1935 524,619 Great Britain Aug. 12, 1940