Electromagnetic musical pickups with central permanent magnets

• US 5,408,043 A
• Filed: 12/30/1992
• Issued: 04/18/1995
• Est. Priority Date: 10/10/1990
• Status: Expired due to Term

• Current Assignee: DORN, THOMAS E. - 25%
• Original Assignee: Thomas E. Dorn
• Inventors: Lace, Melvin A.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): DONELS, JEFFREY
• Application Number:
  US07/998,734
• Time in Patent Office: 839 Days
• Field of Search: 84/723, 84/725, 84/726, 84/743, 84/727-729
• US Class Current: 84/726
• CPC Class Codes: G10H 2220/515 Staggered, i.e. two coils side by side
• CPC Class Codes: G10H 3/181 Details of pick-up assemblies

Abstract

An electromagnetic pickup for a musical instrument (e.g. a guitar) having a plurality of ferromagnetic strings coplanar and parallel with each other, the pickup being adapted to be mounted adjacent to but spaced from the strings includes an elongated electrical pickup coil having a longitudinal central opening, the opening having a length at least as great as the span S of the strings. The pickup also includes an elongated main permanent magnet having a length L such that L>S and an elongated ferromagnetic shell having a length at least as great as S. The main permanent magnet, the pickup coil, and the shell are assembled together in an electromagnetic pickup assembly in which at least one side of the pickup coil is enclosed by the shell, and the main permanent magnet is parallel to the central opening of the coil; the assembly generates a magnetic field which encompasses at least one portion of the pickup coil. A housing mounts the pickup assembly on the musical instrument with the top of the coil facing the instrument strings, which intercept a portion of the magnetic field.

Claims

1. An electromagnetic pickup for a musical instrument, such as a guitar, having a plurality of ferromagnetic strings disposed in spaced relation to each other and extending parallel to each other over a predetermined span S, the pickup being adapted to be mounted adjacent the strings in spaced relation thereto, the pickup comprising:

an elongated electrical pickup coil having two elongated portions on opposite sides of a longitudinal central opening, the opening having a length at least as great as S, and the coil having a predetermined height H;

an elongated main permanent magnet having a length L such that L>

S;

and an elongated ferromagnetic shell having a length at least as great as S and a height greater than H;

the ferromagnetic shell including two elongated shell members of J-shaped cross-sectional configuration, each shell member having a base, a long leg projecting normal to the base from one edge of the base, and a short leg projecting normal to the base from the opposite edge of the base, the shell members being disposed with the short leg of each shell member facing the short leg of the other at the center of the assembly and with the short leg of each shell member having an upper edge facing toward the instrument strings; and

the main permanent magnet, the pickup coil, and the shell being assembled together in an electromagnetic pickup assembly with the pickup coil disposed in encompassing relation to the two short legs of the shell members, in which assembly;

at least one elongated portion of the pickup coil is enclosed on three sides by the shell;

the main permanent magnet extends parallel to the central opening of the coil; and

the assembly generates a magnetic field which encompasses at least the one portion of the pickup coil;

and mounting means for mounting the pickup assembly on the musical instrument with the top of the coil facing but spaced from the strings of the instrument and with those strings intercepting a portion of the magnetic field.

2. An electromagnetic pickup for a plural ferromagnetic string musical instrument, according to claim 1 in which:

the main permanent magnet is aligned with and extends along the upper edges of the shorter legs of the two shell members; and

the main permanent magnet is magnetized in a direction perpendicular to the instrument strings and perpendicular to the bottoms of the two shell members.

3. An electromagnetic pickup for a plural ferromagnetic string musical instrument, according to claim 2 and further comprising:

a thin, elongated secondary permanent magnet interposed between the shorter legs of the two shell members;

the secondary permanent magnet being magnetized transversely, in a direction transverse to the legs of the shell members and parallel to the instrument strings.

4. An electromagnetic pickup for a plural ferromagnetic string musical instrument, according to claim 2, in which:

the main permanent magnet includes a plurality of elongated layers, all of the same configuration and all made of permanent magnet material, stacked in the direction of magnetization for the main permanent magnet.

5. An electromagnetic pickup for a plural ferromagnetic string musical instrument, according to claim 4, and further comprising:

an elongated, thin, ferromagnetic member, having the same configuration as the main permanent magnet layers, interposed between two layers of the main permanent magnet.

6. An electromagnetic pickup for a musical instrument, such as a guitar, having a plurality of ferromagnetic strings disposed in spaced relation to each other and extending parallel to each other over a predetermined span S, the pickup being adapted to be mounted adjacent the strings in spaced relation thereto, the pickup comprising:

an elongated electrical pickup coil having two elongated portions on opposite sides of a longitudinal central opening, the opening having a length at least as great as S, and the coil having a predetermined height H;

an elongated main permanent magnet having a length L such that L>

S;

and an elongated ferromagnetic shell having a length at least as great as S and a height greater than H;

the ferromagnetic shell includes two elongated J-shaped shell members of J-shaped cross-sectional configuration, each shell member having a base, a long leg projecting normal to the base from one edge of the base, and a short leg projecting normal to the base from the opposite edge of the base, the shell members being disposed with the short leg of each shell member facing the short leg of the other at the center of the assembly and with the short leg of each shell member having an upper edge facing toward the instrument strings;

the pickup further comprising a second elongated pickup coil, the two pickup coils having approximately the same size and configuration; and

each of the two electrical pickup coils are disposed in encompassing relation to the long leg of a respective one of the shell members.

7. An electromagnetic pickup for a plural ferromagnetic string musical instrument, according to claim 6 in which:

the main permanent magnet is disposed between the two short legs of the two shell members; and

the main permanent magnet is magnetized transversely to present a north pole facing the short leg of one shell member and a south pole facing the short leg of the other shell member.

8. An electromagnetic pickup for a plural ferromagnetic string musical instrument, according to claim 7 in which:

the main permanent magnet has a height greater than H and projects beyond the short legs of the shell members in at least one direction perpendicular to the plane of the strings.

9. An electromagnetic pickup for a plural ferromagnetic string musical instrument, according to claim 8 in which:

the main permanent magnet projects beyond the short legs of the shell members in two directions perpendicular to the strings.

10. An electromagnetic pickup for a musical instrument, such as a guitar, having a plurality of ferromagnetic strings disposed in spaced relation to each other and extending parallel to each other over a predetermined span S, the pickup being adapted to be mounted adjacent the strings in spaced relation thereto, the pickup comprising:

an elongated electrical pickup coil having two elongated portions on opposite sides of a longitudinal central opening, the opening having a length at least as great as S, and the coil having a predetermined height H;

an elongated main permanent magnet having a length L such that L>

S;

and an elongated ferromagnetic shell having a length at least as great as S and a height greater than H;

the main permanent magnet, the pickup coil, and the shell being assembled together in an electromagnetic pickup assembly in which at least one elongated portion of the pickup coil is enclosed on three sides by the shell, the main permanent magnet is aligned with the central opening of the coil, and the assembly generates a magnetic field which encompasses at least the one portion of the pickup coil;

an elongated ferromagnetic core aligned with and extending along the top of the main permanent magnet, the core having a width sufficient to overlap a part of the coil at both sides of the central opening of the coil;

and mounting means for mounting the pickup assembly on the musical instrument with the top of the coil facing but spaced from the strings of the instrument and with those strings intercepting a portion of the magnetic field.

11. An electromagnetic pickup for a plural ferromagnetic string musical instrument, according to claim 10, and further comprising:

an elongated secondary permanent magnet disposed adjacent to the core and magnetized transversely to present a surface of given uniform magnetic polarity facing the core, that given polarity matching the magnetic polarity of the uppermost surface of the main permanent magnet.

12. An electromagnetic pickup for a musical instrument, such as a guitar, having a plurality of ferromagnetic strings disposed in spaced relation to each other and extending parallel to each other over a predetermined span S, the pickup being adapted to be mounted adjacent the strings in spaced relation thereto, the pickup comprising:

two elongated electrical pickup coils each having two elongated portions on opposite sides of a longitudinal central opening, each opening having a length at least as great as S, and each coil having a predetermined height H;

an elongated main permanent magnet having a length L such that L>

S;

and an elongated ferromagnetic shell having a length at least as great as S and a height greater than H;

the main permanent magnet, the pickup coils, and the shell being assembled together in an electromagnetic pickup assembly in which at least one elongated portion of each pickup coil is enclosed on three sides by the shell,

the main permanent magnet is aligned with the central opening of the coils and is magnetized in a direction parallel to the instrument strings, and the assembly generates a magnetic field which encompasses at least the one portion of each pickup coil;

and mounting means for mounting the pickup assembly on the musical instrument with the tops of the coils facing but spaced from the strings of the instrument and with those strings intercepting a portion of the magnetic field.