Classifications

• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10H—ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE
  • G10H3/00—Instruments in which the tones are generated by electromechanical means
  • G10H3/12—Instruments in which the tones are generated by electromechanical means using mechanical resonant generators, e.g. strings or percussive instruments, the tones of which are picked up by electromechanical transducers, the electrical signals being further manipulated or amplified and subsequently converted to sound by a loudspeaker or equivalent instrument
  • G10H3/14—Instruments in which the tones are generated by electromechanical means using mechanical resonant generators, e.g. strings or percussive instruments, the tones of which are picked up by electromechanical transducers, the electrical signals being further manipulated or amplified and subsequently converted to sound by a loudspeaker or equivalent instrument using mechanically actuated vibrators with pick-up means
  • G10H3/18—Instruments in which the tones are generated by electromechanical means using mechanical resonant generators, e.g. strings or percussive instruments, the tones of which are picked up by electromechanical transducers, the electrical signals being further manipulated or amplified and subsequently converted to sound by a loudspeaker or equivalent instrument using mechanically actuated vibrators with pick-up means using a string, e.g. electric guitar
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10H—ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE
  • G10H3/00—Instruments in which the tones are generated by electromechanical means
  • G10H3/12—Instruments in which the tones are generated by electromechanical means using mechanical resonant generators, e.g. strings or percussive instruments, the tones of which are picked up by electromechanical transducers, the electrical signals being further manipulated or amplified and subsequently converted to sound by a loudspeaker or equivalent instrument
  • G10H3/14—Instruments in which the tones are generated by electromechanical means using mechanical resonant generators, e.g. strings or percussive instruments, the tones of which are picked up by electromechanical transducers, the electrical signals being further manipulated or amplified and subsequently converted to sound by a loudspeaker or equivalent instrument using mechanically actuated vibrators with pick-up means
  • G10H3/18—Instruments in which the tones are generated by electromechanical means using mechanical resonant generators, e.g. strings or percussive instruments, the tones of which are picked up by electromechanical transducers, the electrical signals being further manipulated or amplified and subsequently converted to sound by a loudspeaker or equivalent instrument using mechanically actuated vibrators with pick-up means using a string, e.g. electric guitar
  • G10H3/185—Instruments in which the tones are generated by electromechanical means using mechanical resonant generators, e.g. strings or percussive instruments, the tones of which are picked up by electromechanical transducers, the electrical signals being further manipulated or amplified and subsequently converted to sound by a loudspeaker or equivalent instrument using mechanically actuated vibrators with pick-up means using a string, e.g. electric guitar in which the tones are picked up through the bridge structure
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10H—ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE
  • G10H2220/00—Input/output interfacing specifically adapted for electrophonic musical tools or instruments
  • G10H2220/461—Transducers, i.e. details, positioning or use of assemblies to detect and convert mechanical vibrations or mechanical strains into an electrical signal, e.g. audio, trigger or control signal
  • G10H2220/465—Bridge-positioned, i.e. assembled to or attached with the bridge of a stringed musical instrument
  • G10H2220/471—Bridge-positioned, i.e. assembled to or attached with the bridge of a stringed musical instrument at bottom, i.e. transducer positioned at the bottom of the bridge, between the bridge and the body of the instrument
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10H—ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE
  • G10H2220/00—Input/output interfacing specifically adapted for electrophonic musical tools or instruments
  • G10H2220/461—Transducers, i.e. details, positioning or use of assemblies to detect and convert mechanical vibrations or mechanical strains into an electrical signal, e.g. audio, trigger or control signal
  • G10H2220/465—Bridge-positioned, i.e. assembled to or attached with the bridge of a stringed musical instrument
  • G10H2220/495—Single bridge transducer, common to all strings
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10H—ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE
  • G10H2220/00—Input/output interfacing specifically adapted for electrophonic musical tools or instruments
  • G10H2220/461—Transducers, i.e. details, positioning or use of assemblies to detect and convert mechanical vibrations or mechanical strains into an electrical signal, e.g. audio, trigger or control signal
  • G10H2220/525—Piezoelectric transducers for vibration sensing or vibration excitation in the audio range; Piezoelectric strain sensing, e.g. as key velocity sensor; Piezoelectric actuators, e.g. key actuation in response to a control voltage
  • G10H2220/531—Piezoelectric transducers for vibration sensing or vibration excitation in the audio range; Piezoelectric strain sensing, e.g. as key velocity sensor; Piezoelectric actuators, e.g. key actuation in response to a control voltage made of piezoelectric film
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10H—ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE
  • G10H2220/00—Input/output interfacing specifically adapted for electrophonic musical tools or instruments
  • G10H2220/461—Transducers, i.e. details, positioning or use of assemblies to detect and convert mechanical vibrations or mechanical strains into an electrical signal, e.g. audio, trigger or control signal
  • G10H2220/525—Piezoelectric transducers for vibration sensing or vibration excitation in the audio range; Piezoelectric strain sensing, e.g. as key velocity sensor; Piezoelectric actuators, e.g. key actuation in response to a control voltage
  • G10H2220/531—Piezoelectric transducers for vibration sensing or vibration excitation in the audio range; Piezoelectric strain sensing, e.g. as key velocity sensor; Piezoelectric actuators, e.g. key actuation in response to a control voltage made of piezoelectric film
  • G10H2220/535—Piezoelectric polymer transducers, e.g. made of stretched and poled polyvinylidene difluoride [PVDF] sheets in which the molecular chains of vinylidene fluoride CH2-CF2 have been oriented in a preferential direction

Definitions

• This invention relates to contact microphones for guitars and like instruments, that is instruments having strings stretched over a bridge, and principally those where the strings are plucked, for example guitars, banjos and mandolins.
• contact microphones on instruments has been known for some time, but hitherto they have been subject to a number of disadvantages with respect to sound quality when compared with good quality conventional microphones. Also, the noises of the player handling the instrument and moving his fingers on the strings would often seriously interfere with the sound desired; this makes the instrument very hard to play. Nevertheless, contact microphones are commonly used because of their convenience when compared with separate microphones with supporting stands etc.
• the present invention deals with a contact microphone system which addresses . he problems outlined above with a view to producing a contact microphone which is actually superior to conventional (non-contact) microphones.
• the invention provides a contact microphone for a guitar or like instrument, comprising a sheet of polymeric piezoelectric material adapted to be interposed between the bridge and the body of the instrument and having electrode areas arranged to sense voltages induced in ⁇ aid sheet by deformation thereof caused by predetermined modes of vibration while being insensitive to other modes of vibration.
• the required sensitivity may be achieved by shaping of the electrode areas, by the use of a piezoelectric material having a predominantly uniaxial response aligned with the strings of the instrument, or both of these.
• the invention provides two types of embodiment which can be used separately or together depending on the fidelity required.
• the first is applied to the bridge of . the instrument in such a manner as to produce an output corresponding to vibration perpendicular to the strings but no output for vibration axially of the strings.
• the second is applied to the saddle plate of the instrument to give an output reproducing low frequencies associated with body resonance.
• Fig. 1 shows a microphone of the first type of embodiment
• Fig. 2 is a side view of the microphone of Fig. 1 applied to the bridge of a guitar;
• Fig. 3 is a perspective view showing the assembly of Fig. 2 in position on the saddle plate of the guitar.
• Fig. is a plan view illustrating a microphone of the second type applied to the saddle plate of a guitar.
• the microphone comprises a shaped sheet 10 of a polymeric piezoelectric material, preferably/ polyviny/lidene fluoride (PVDF).
• PVDF polyviny/lidene fluoride
• the sheet 10 is most suitably of uniaxial PVDF having its axis of piezoelectric activity .in the direction A-A whereby in use said axis is aligned with the strings of the guitar.
• An electrode pattern 12 is printed on the sheet 10, suitably with silver ink, the pattern 12 consisting of a central bar 12a and oppositely-extending truncated triangles 12b at each string position.
• the reverse of the sheet 10 is covered with a continuous metallised conductive ground plane and conductors (not shown) are connected to the pattern 12 and to the ground plane to provide the output signal.
• Fig. 1 The assembly of Fig. 1 is wrapped around the bridge 1 as seen in Fig. 2, and this is then inserted in the customary slot in the saddle plate 16 of the guitar (Fig. 3).
• the sahped conductor 12 may be positioned next the bridge 14 with the ground plane to the outside, or the continuous ground plane may be replaced by another conductor of the same shape and positioning as the conductor 12.
• the base film is prepared from vinylidene fluoride homo olymer, film grade resin (YNAR (trade mark) 9816-30 from Pennwalt Corporation) by melt extrusion.
• the base film is uniaxially stretch oriented at a stretch ratio ranging between about 4 and 5 to 1 to produce a film having a thickness of about 28 microns. This thickness is not critical but is preferred for the present use.
• the film is then electrically polarized (poled) in known manner by subjecting the film to a pressure of about 300 psi, a temperature of about 65 C, and voltage of
• the poled film is then electroded, with silver ink, by silk screen painting multiple patterns of the type shown in Fig. 1 on one side of the film and then repeating this painting process on the other side of the film to provide a corresponding and aligned pattern of silver ink on the opposite side of the film.
• Electrodes are attached to the electrode pattern on each side of the film and two-side-coated adhesive plastic film is applied to the electrically positive side of the film.
• the laminate is die cut over the electrode patterns to provide a transducer which is about as long as the bridge and about as wide as the total width of the two sides and the base of the bridge to which it is to be attached.
• the pickup is connected through the leads to a power source and amplifier, as is conventionally arranged.
• the bridge 14 be at least thicker than one-third the thickness of the thickest string, and preferably thicker than the thickest string, passing over it.
• Fig. 4 The saddle plate of the guitar (such as the saddle plate 16 of Fig. 3) has secured between it and the guitar body a relatively large sheet of uniaxial PVDF, suitably the same material as that described in detail above, with the axis of sensitivity aligned with the strings. Holes are provided at A or B for passage of the strings; in the example shown both are provided to enable the pickup to fit various guitars.
• a conductive pattern 22 is printed on the top surface of the sheet 20 to act as a sensing electrode, and the rear surface again is provided over its whole surface with a conductive ground plane. Holes 24 through the sheet are plated through to provide electrical interconnection at these points between the pattern 22 and the ground plane. This has the effect that the areas of the conductive pattern act as individual pickups connected in series.
• a suitable pattern 22 consists of four strips transverse to the strings, together with printed connectors.
• these strips are each 8.5 n_ wide and are spaced 3.0 mm apart.
• both sides of the sheet 20 could be provided with a continuous metallised conductive layer.
• a transducer would have a very large capacit- ance, and the pattern described is preferred to reduce the capacitance and produce an impedance similar to that of the bridge pickup of Figs. 1-3.
• the sheet 20 produces signals resulting from compression under the bridge and stretching in the string direction, and its sensitivity is approximately equal between the change in length caused by the swing of a node and the compression signal from the bridge.
• the signal is largely defined by the load rather than actual movement of the guitar body, and thus the output from handling is still relatively low as the bridge acoustic impedance is higher than any other similar area of the body.
• the pickup of Fig. 4 ma be used on its own, but the damping of transients by the significant masses in the way makes it less suitable than the pickup of Figs. 1-3.
• the bridge pickup provides the transient and major harmonic information and the second pickup provides the low frequency information which gives the instrument its solidity.
• the second pickup canbe dispensed with for all but the most critical applications such as the amplification and recording of classical guitar or for solo work on record. It is probably not necessary for most group work on record or stage work.
• the combination of the two pickups can produce a sound which by all practical means of observation is identical to the unamplified guitar but louder (assuming, of course, that the amplification and speaker systems are of top quality).
• the invention can be used with other stringed instruments having a bridge resting in a slot.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Stringed Musical Instruments (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10580420

Family Applications (1)

Country Status (8)

Cited By (3)

Citations (2)

• 1985
  • 1985-06-08 GB GB858514542A patent/GB8514542D0/en active Pending
• 1986
  • 1986-06-06 EP EP86903508A patent/EP0225365A1/en not_active Withdrawn
  • 1986-06-06 WO PCT/GB1986/000320 patent/WO1986007484A1/en not_active Application Discontinuation
  • 1986-06-06 JP JP61503251A patent/JPS63500270A/ja active Pending
  • 1986-06-06 BR BR8606715A patent/BR8606715A/pt unknown
  • 1986-06-06 AU AU59672/86A patent/AU5967286A/en not_active Abandoned
• 1987
  • 1987-02-02 DK DK053287A patent/DK53287A/da not_active Application Discontinuation
  • 1987-02-06 KR KR870700104A patent/KR880700385A/ko not_active Application Discontinuation

Patent Citations (2)

Non-Patent Citations (1)

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