|Publication number||US3530228 A|
|Publication date||Sep 22, 1970|
|Filing date||Apr 23, 1968|
|Priority date||Apr 23, 1968|
|Publication number||US 3530228 A, US 3530228A, US-A-3530228, US3530228 A, US3530228A|
|Inventors||Robert C Scherer|
|Original Assignee||Baldwin Co D H|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (29), Classifications (11), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Sept. 22, 1970 R, c. sc 3,530,228
ELECTRIC GUITAR PIEZOELECTRIC TRANSDUCER BRIDGE WITH REPLACEABLE STRING HEIGHT ADJUSTORS Filed April 23, 1968 INVENTOR 16 ROBERT C. SCHERER 1 2 I BYM/ ATTORNEYS United States Patent O 3,530,228 ELECTRIC GUITAR PIEZOELECTRIC TRANS- DUCER BRIDGE WITH REPLACEABLE STRING HEIGHT ADJUSTORS Robert C. Scherer, Cincinnati, Ohio, assignor to D. H. Baldwin Company, Cincinnati, Ohio, a corporation of Ohio Continuation-impart of application Ser. No. 483,679, Aug. 30, 1965. This application Apr. 23, 1968, Ser. No. 723,535
Int. Cl. G10d 3/04, /00
U.S. Cl. 84-116 Claims ABSTRACT OF THE DISCLOSURE CROSS REFERENCES This application is a continuation-in-part of my application, Ser. No. 483,679, entitled Electric Guitar Bridge, filed Aug. 30, 1965, now US. Pat. No. 3,396,284 issued Aug. 6, 1968, and assigned to the assignee of this application.
BACKGROUND OF THE INVENTION Electric guitars are conventionally provided with transducers, capable of providing output in response to the vibrations of the strings when the latter are picked or plucked. In such guitars the modes of vibrations of the strings vary with time, from initial excitation to final decay, and, in particular, picking or plucking a string may induce a vibration in one plane in space while the free vibration in one plane in space while the free vibrations of the string may be in another plane, or the plane may oscillate in space, depending on the precise character of the excitation.
Guitar players desire that the sound of an electric guitar be similar to that of an acoustic guitar, but the conventional electromagnetic transducers employed in electric guitars are not capable of responding to all planes of vibration of a string, and usually can respond only to vertical vibrations, whereby the initial excitation of the string, which is predominately horizontal, is lost. Nor can such transducers operate in conjunction with nylon or other non-metallic strings.
It is a function of the present invention to provide a string transducer, especially for an electric guitar, which responds to vibrations of a string occurring in any plane, and which responds equally well to metallic and nonmetallic strings.
My prior application discloses an aluminum extrusion of U-shaped transverse cross section, one arm of which is supported on a guitar body, and the other arm of which has slots to define separate cantilevers for each string of the guitar. Piezoelectric transducers are provided under each cantilever. The slots acoustically isolate the several strings, and the several cantilevers. Provision is made for string length adjustment, and each cantilever is provided with a string locating notch.
It is found that the sophisticated musician desires individual adjustment of string heights. Such adjustment can be provided by filing the bone to adjust individual string heights. The difiiculty ensues that if the bone is overfiled the entire bridge must be discarded. The present invention concerns itself with providing a nylon or other acoustically isolating readily filable element, as part of the bridge, which can have its height individually formed, to adjust string heights on an individual or group basis, and which can be readily replaced if desired. Provision is additionally made for closely coupling the bridge acoustically to the body of the guitar via a wooden spacer, while providing for screw adjustment of the extrusion bridge with respect to the spacer.
Briefly describing a preferred embodiment of the invention, an elongated metallic extrusion is provided, having the cross section of a U. One arm of the U forms a base which is supported on the body of a guitar, at the usual bridge location. The other arm is arranged to provide plural cantilever arms, for separately supporting each string of the guitar. Considering one string only, for simplicity of explanation, a piezoelectric crystal is placed between the base and a cantilever arm. Overlying the crystal is a thin sheet copper; i.e. shim stock or the like. Underlying the crystal is a further shim and under the latter is a sheet of insulation whichhas acoustic damping properties. The two copper sheets then make contact with the electrodes of the crystal and can be conveniently connected to output leads.
SUMMARY OF THE INVENTION A transducer string bridge includes provision for string length adjustment while enabling close acoustic coupling of the transducer to the body of the guitar, and also provision for individual string height adjustment in terms of a readily replaceable nylon filament on which the strings rest, the filament providing operatively negligible acoustic coupling between strings. o
BRIEF DESCRIPTION OF THE DRAWINGS The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is a view in perspective of a guitar having a transducer bridge according to the invention;
FIG. 2 is a view in perspective of a transducer bridge assembly according to the invention;
FIG. 3 is a view in plan of the transducer bridge assembly of FIG. 2;
FIG. 4 is a view in transverse cross section taken on the line 4-4 of FIG. 3; and
FIG. 5 is a view in transverse cross section taken on the line 55 of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the accompanying drawings, 10 is an elongated extrusion, which may be made of aluminum, brass, or the like, and which has a U-shape when taken in cross section. Arm 11 of the U is a base arm. The further or upper arm 14 of the extrusion is provided with transverse slots 15, which extend into the end wall 10a, of the U, and form plural cantilever arms 14a. An in verted V-shaped riser 17 is provided near the forward edge of each arm 14a.
The cantilever arms form individual supports for the strings, which are acoustically largely isolated from one another by the slots 15.
Located under each cantilever arm 14a is a piezoelectric crystal 20. Under the crystals is a strip of thin shim stock 21. Under each strip of shim stock 21 is a strip 22, of
insulation, which is resilient mechanically and which damps acoustic vibrations. Overlying crystal 20 is a further strip of shim stock 23. Strip 21 thus forms one electrode for all of crystal 20, and strip 23, grounded to the extrusion, forms the other electrode. Leads 25 are connected to strips 21 and 23.
The use of acoustic damping material 22 is particularly important because it serves to damp out undesirable highs, as clicks, pops, finger noise and the like, and also serves to acoustically isolate the crystals 20 from one another.
The transducer bridge is slidably mounted on a wooden base plate 16, which is in turn glued to the instrument. Screw adjusting means 41, 41a are provided for longitudinally adjusting the position of the transducer bridge 10 with respect to the base plate 16, by turning nuts 41a on bolts 41.
Longitudinal grooves 42, of generally rectangular crosssection, are cut in the cantilevers 14a, in which is fitted a nylon filament 43. The latter is about A in width, and snugly fits the grooves 42. The filament 43 is sometimes called a bone. It possesses a high degree of acoustic insulation longitudinally, so that crystals remain acoustically isolated from each other. In the thickness mode, however, the filament 43 closely couples the strings 44 to the cantilever 14a, and thence to the body of the guitar.
A wooden string support 40 includes two wings 45, 46 which are cemented to the body of the guitar G. The extrusion 10 extends between the wings 45, 46, resting on a wooden spacer 16, which in turn rests on the body of the guitar, and behind the extrusion 10 is located a wooden bridging member 47, integral with wings 45, 46, resting on and cemented to the body of guitar G. Extending rearwardly of the extrusion 10 are the two bolts 41, which are immovable with respect to the extrusion. The bridging member 47 includes horizontal apertures 50, through which bolts 41 extend, into a rearward slot 51. The bolts 41 are immovably secured to the extrusion 10 by means of vertical pins 52, extending through the extrusion 10 and also through the bolts 41.
Nut 41a, pertaining to the screws 41, extend into the slot 51. By turning the nuts 41a the screws 41, and similarly the extrusion 10, may be moved longitudinally of the guitar G, to adjust string length.
The bridging member 47 also includes openings 55 for the strings 44, through which the strings extend and are knotted around the bridging member 47.
The extrusion 10 may be potted with soft rubbery material, which does not appreciably reduce amplitude of vibrations of the crystals 20, but which does maintain the elements of the transducer in place and enhance its aesthetic appeal. Suflicient pressure exists on the crystals 20 to assure that these will operate linearly with respect to vibrations imparted thereto.
While I have described and illustrated one specific embodiment of my invention, it will be clear that variation of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.
What is claimed is:
1. In a transducer bridge for a stringed instrument,
an aluminum extrusion of U-shaped transverse crosssection, said aluminum extrusion providing a base,
means for supporting said base on said stringed instrument,
said aluminum extrusion providing discrete cantilever arms extending parallel to said base, there being one cantilever arm for each string of said stringed instrument,
a separate piezoelectric element located between each cantilever arm and said bridge and compressed therebetween,
means for deriving voltages from said piezoelectric elements which are developed in response to vibrations of said strings and are communicated to said piezoelectric elements via said cantilever arms, and
a filament extending lengthwise of said cantilever arms and located between said strings and said cantilever arms,
said filament having operatively negligible lengthwise acoustic coupling and being sufficiently soft that string height may be readily adjusted by removing material from the filament,
said cantilevers including lengthwise of said extrusion a groove for locating and retaining said filament.
2. The combination according to claim 1 wherein is provided a non-metallic separator located between said base and said stringed instrument, and
screw means for adjusting the longitudinal position of said transducer bridge with respect to said string instrument.
3. In a transducer bridge for a stringed instrument,
a U-shaped elongated metallic member,
one of the arms of said member providing a flat base,
the other of the arms of said member being slotted to provide a plurality of cantilever arms extending parallel to said base,
a piezoelectric crystal element located intermediate each of said cantilever arms and said base and in contact with both one of said cantilever arms and said base,
a layer of electrically conductive material underlying and in contact with said piezoelectric elements,
an electric and acoustic insulating layer underlying said layer of electrically conductive material,
a further layer of electrically conductive material overlying said crystal and in contact with said cantilever arms, and
string loacting filamentary means extending longitudinally of said cantilever arms and supported thereby and separable therefrom.
4. The combination according to claim 3, wherein said filamentary means is a single filament.
5. The combination according to claim 3, wherein said filamentary means is a nylon filament.
'6. The combination according to claim 3, wherein said filamentary means is sufliciently soft that string height may be readily selected by removing material from said filamentary means to desired extends individual to each string.
7. The combination according to claim '6, wherein said cantilever arms include longitudinal grooves for locating said filamentary means.
'8. In a transducer assembly for a stringed instrument,
a wooden element extending transversely of said instrument and cemented thereto,
said wooden element including two wings separated by a bridging element,
an acousto-electric transducer bridge for said strings extending between said wings and movable with respect to said instrument, and
screw threaded means engaging said transducer bridge and said bridging element for moving said transducer With respect to said bridging element, thereby to adjust the eifective lengths of the strings of said stringed instrument,
wherein said acousto-electric transducer bridge includes an extrusion of U-shape in transverse section, and
acousto-electric transducers positioned between the arms of said extrusion, the strings of said instrument resting on one arm of said extrusion and the other arm resting on said instrument, and
slots in said one arm defining individual cantilevers for each of said strings.
9. The combination according to claim 8 wherein is provided filamentary interposer means located between said string and said one of said arms.
10. The combination according to claim 8, wherein said bridging element includes apertures through which said 6 strips extend, ends of said strings being secured to said 3,301,936 1/1967 Carman et a1 841.16 bridging element. 3,396,284 8/1968 Scherer 3108.3
References Cited 931689 s/l ggj G PATENTS UNITED STATES PATENTS 5 2,764,052 9/ 1956 McBride 84-1.15 WARREN E. RAY, Primary Examiner 3,066,567 12/1962 Kelley 84l.16 3,073,203 1/1963 Evans 841.16
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|U.S. Classification||84/731, 984/371, 84/DIG.240, 84/743|
|Cooperative Classification||G10H2220/485, Y10S84/24, G10H2220/525, G10H3/185, G10H2220/471|
|Feb 13, 1985||AS02||Assignment of assignor's interest|
Owner name: FRED W. GRETSCH ENTERPRISES, LTD., 715 GRAYS HIGHW
Owner name: GRETSCH COMPANY THE
Effective date: 19850102
|Feb 13, 1985||AS||Assignment|
Owner name: FRED W. GRETSCH ENTERPRISES, LTD., 715 GRAYS HIGHW
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:GRETSCH COMPANY THE;REEL/FRAME:004361/0184
Effective date: 19850102