Electromagnetic musical pickup using main and auxiliary permanent magnets

• US 5,389,731 A
• Filed: 07/13/1993
• Issued: 02/14/1995
• Est. Priority Date: 10/10/1990
• Status: Expired due to Fees

• 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:
  US08/090,318
• Time in Patent Office: 581 Days
• Field of Search: 84/723, 84/725, 84/726, 84/728
• 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 assembly for a musical instrument, such as a guitar, strung with ferromagnetic strings, comprises two elongated high permeability ferromagnetic (steel or iron) cores each long enough to span some but not all of the strings; preferably, there are several thin steel laminations in the core. Two electrically conductive pickup coils are wound in coil forms, usually plastic; one such coil form encompasses each core. There are two vertically magnetized main permanent magnets, each having a high energy product (BxH); each main magnet engages the bottom edge of one core and maintains that core at a given polarity. A housing or other mounting members mount the cores, the coils, and the main permanent magnets in spaced relation to the strings so that the pickup generates two magnetic fields that, together, encompass all of the strings, whereby movement of any string or combination of strings generates electrical signals in the coils. Auxiliary permanent magnets of low energy product (BxH) material shield the sides of the cores and their coils; one such auxiliary permanent magnet may shield both cores.

Claims

1. An electromagnetic pickup for a musical instrument, such as a guitar, having a given number of ferromagnetic strings, the pickup comprising:

an elongated high permeability ferromagnetic core, having a length L1 sufficient to span a plurality of less than all of the musical instrument strings, a height H1, and a width W1;

an elongated electrically conductive pickup coil disposed in encompassing relation to the ferromagnetic core;

a main permanent magnet, formed of a first permanent magnet material having a first high energy product, disposed in alignment with one elongated edge of the core, the main permanent magnet being magnetized in a direction transverse to the core height to maintain a given constant magnetic polarity in the core;

auxiliary permanent magnet means, comprising at least one elongated auxiliary permanent magnet, formed of a second permanent magnet material having an energy product materially lower than the first energy product, disposed immediately adjacent one side of the pickup coil, the auxiliary permanent magnet having a length L2 greater than L1 and a height H2 at least as large as H1;

and means for mounting the core, the coil, the main permanent magnet, and the auxiliary permanent magnet on the musical instrument with the core and the coil spanning a plurality of less than all of the ferromagnetic strings, in spaced relation thereto, and with that plurality of strings passing through a magnetic field afforded by the main permanent magnet and the core so that movement of any string of the plurality of strings generates an electrical signal in the coil.

2. An electromagnetic pickup for a ferromagnetic string musical instrument, according to claim 1, in which the core includes a plurality of ferromagnetic sheet steel laminations each having a thickness no greater than about 0.025 inch (0.06 cm).

3. An electromagnetic pickup for a ferromagnetic string musical instrument, according to claim 1, in which the electrical pickup coil is formed of 46 gauge or larger copper wire.

4. An electromagnetic pickup for a ferromagnetic string musical instrument, according to claim 1, in which the auxiliary permanent magnet means comprises a plurality of auxiliary permanent magnets.

5. An electromagnetic pickup for a ferromagnetic string musical instrument, according to claim 1, in which the auxiliary permanent magnet means covers both long sides of the pickup coil.

6. An electromagnetic pickup for a ferromagnetic string musical instrument, according to claim 1, in which the auxiliary permanent magnet means covers all sides of the pickup coil.

7. A dual coil electromagnetic pickup assembly for a musical instrument, such as a guitar, having a given number of ferromagnetic strings, the pickup assembly comprising:

first and second elongated high permeability ferromagnetic cores, each core having a length L1 sufficient to span a plurality of less than all the ferromagnetic strings, and a smaller height H1, the cores spanning all of the strings of the instrument;

first and second elongated electrically conductive pickup coils, each coil disposed in encompassing relation to one of the ferromagnetic cores;

first and second main permanent magnets, each formed of a first permanent magnet material having a first high energy product, each main permanent magnet disposed in alignment with one elongated edge of one of the cores and magnetized in a direction transverse to its associated core height, for maintaining a given constant magnetic polarity in the associated core;

auxiliary permanent magnet means, comprising at least one elongated auxiliary permanent magnet formed of a second permanent magnet material having an energy product materially lower than the first energy product, the auxiliary permanent magnet having a height H2 at least as large as H1 and being disposed immediately adjacent one side of each pickup coil;

and means for mounting the core, the coil, the main permanent magnet, and the auxiliary permanent magnet means on the musical instrument with each core and its associated coil spanning a plurality of less than all of the ferromagnetic strings in spaced relation thereto and with each plurality of strings passing through a magnetic field afforded by the main permanent magnet and the core related to that plurality of strings so that movement of any string of the plurality generates an electrical signal in the associated coil.

8. A dual-coil electromagnetic pickup assembly for a ferromagnetic string musical instrument, according to claim 7, in which each core includes a plurality of ferromagnetic sheet steel laminations, each lamination having a thickness no greater than about 0.025 inch (0.06 cm).

9. A dual-coil electromagnetic pickup assembly for a ferromagnetic string musical instrument, according to claim 7, in which the auxiliary permanent magnet means includes a plurality of auxiliary permanent magnets, each magnetized transversely and each presenting a surface, facing its associated core and pickup coil, having the same polarity as the polarity of the main permanent magnet engaging the edge of the core encompassed by that coil, so that each core is enclosed by surfaces of the same magnetic polarity on all sides.

10. A dual-coil electromagnetic pickup assembly for a ferromagnetic string musical instrument, according to claim 9, in which one auxiliary permanent magnet serves both pickup coils.

11. An electromagnetic pickup assembly for a ferromagnetic string musical instrument, according to claim 7, in which the polarities of the first and second main permanent magnets are oriented oppositely to each other.

12. A dual coil electromagnetic pickup assembly for a musical instrument, such as a guitar, having a plurality of ferromagnetic strings, the pickup assembly comprising:

first and second elongated ferromagnetic cores, each core having a length L1 sufficient to span a plurality of the musical instrument strings and a smaller height H1;

first and second electrically conductive pickup coils, each disposed in encompassing relation to one of the ferromagnetic cores;

the first core and coil being displaced longitudinally from the second coil and core, transversely of the strings, with each string aligned with at least one coil;

first and second permanent magnet means, each including a main permanent magnet disposed immediately adjacent one elongated edge of a respective one of the cores and magnetized in a direction transverse to the height of its associated core, for maintaining a given constant polarity in the associated core;

and auxiliary permanent magnet means, including at least a first auxiliary permanent magnet adjacent a side of the first coil and first core and a second auxiliary magnet adjacent a side of the second coil and second core, each auxiliary magnet being magnetized transversely and presenting a surface, facing its associated pickup coil, having the same polarity as the polarity of the main permanent magnet adjacent the edge of the core encompassed by that coil.

13. An electromagnetic pickup assembly for a ferromagnetic string musical instrument, according to claim 12, in which the first coil and core is further displaced longitudinally of the strings relative to the second coil and core.

14. An electromagnetic pickup assembly for a ferromagnetic string musical instrument, according to claim 12, in which the first and second auxiliary permanent magnets constitute a single permanent magnetic member that is aligned adjacent both the first coil and core and the second coil and core.

15. An electromagnetic pickup assembly for a ferromagnetic string musical instrument, according to claim 12, in which the first and second main permanent magnets are oriented so that they are polarized oppositely to each other.