WO1992013336A1

WO1992013336A1 - Electromagnetic transducer

Info

Publication number: WO1992013336A1
Application number: PCT/GB1992/000109
Authority: WO
Inventors: Alan Entwistle
Original assignee: M Hohner Limited
Priority date: 1991-01-18
Filing date: 1992-01-17
Publication date: 1992-08-06
Also published as: GB2253509A; GB9101141D0; GB9200974D0; GB2253509B

Abstract

An electromagnetic transducer for a musical instrument, such as a guitar, has ceramic magnets (10a, 10b), a laminated core (11) and insulated wire (12) wound around said core. In use, the transducer is placed in magnetic proximity to, for example, the strings on an electric guitar, and the laminations in the core reduce eddy currents in the transducer and produce a high apex magnetic field.

Description

ELECTROMAGNETIC TRANSDUCER

The present invention relates to an electromagnetic transducer for a musical instrument, having a core and at least one insulated conductive winding wound around said core.

Electric guitars employ electromagnetic transducers for converting the mechanical vibrations of the strings into electrical signals. In known transducers, the core is made from one or a plurality of magnets arranged such that the magnetic field generated by said magnets passes through the vibrating strings which modify the magnetic field and induce a current in the insulated windings.

It is known that the nature and configuration of the electromagnetic transducer affects the tonal content of the output signal, which usually requires several stages of amplification before being supplied to an audible loud speaker. Furthermore, the quality of the output signal, in terms of its noise content, will also be significantly affected by the signal to noise ratio of the transducer itself and attempts have been made to increase the output level of transducers whilst minimising noise. For example, a known technique for increasing the output of a transducer is to increase the number of insulated windings wound around the core, which in turn necessitates a reduction in the diameter of the winding wire. Unfortunately, the use of very thin wire in order to achieve an increased number of windings also introduces disadvantages, particularly in connection with the tonal content of the output signal, which can be very important if the level of active filtering and amplification, which in turn introduce noise, is to be minimised.

It is an object of the present invention to provide an improved electromagnetic transducer. In particular, it is an object of the present invention to provide an electromagnetic transducer arranged to have a high output while maintaining good tonal qualities.

According to a first aspect of the present invention, there is provided an electromagnetic transducer of the aforesaid type, characterised in that said core is fabricated from a plurality of laminations.

In a preferred embodiment, the laminations are molecularly aligned steel plates and a core may be fabricated from between three and thirty of said plates. Preferably, the conductive windings are insulated copper wire which may have a diameter of between 0.04mm and 0.10mm. Preferably, a magnetic field is created around and through said core and said magnetic field may pass through said core in a direction substantially parallel to said laminations. In a preferred embodiment, the magnetic field is created by a pair of magnets placed along side of said core and said magnets may be of the ceramic type. According to a second aspect of the invention, there is provided an electromagnetic transducer, comprising at least two ceramic magnets and a portion of high-carbon copper wire; the high-carbon copper wire being operatively wound around a core, said core having a plurality of laminations; wherein said ceramic magnets are operatively positioned with respect to the core, such that at least some lines of flux extending from said magnets pass through the core and extend substantially parallel to at least one of the laminations.

Preferably, the electromagnetic transducer may be used with an electric guitar and in a preferred embodiment, said guitar has tone control means as described in the present applicant's co-pending United Kingdom patent application number 9101105, filed on 18 January 1991.

The invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows, schematically, a side view of a preferred transducer for a guitar; figure 2 shows an end view of the transducer of Figure 1 ; figure 3 is a view from above of the transducer of Figures 1 and 2; figure 4 is a perspective view of a transducer without winding; figure 5 shows a flux field pattern of the transducer of Figures 1 to 3; and figure 6 shows two adjacent laminations of the transducer of Figures 1 to 3.

Referring particularly to Figures 1 to 4, elongate ceramic magnets 10a and 10b are positioned adjacent to a laminated core 11 which comprises a plurality of laminations, the laminations comprising transformer steel plates which are molecularly aligned (each plate being orientated in an opposite sense to its nearest neighbours as shown in Figure 6).

A winding 12 of 0.06mm high-carbon copper (not shown in its entirety) is wound on a bobbin 13 around the core 11.

When the transducer is used with an electric guitar, the movement of the strings of the electric guitar disturb the magnetic field associated with the transducer, the pattern of flux lines of the transducer being shown in Figure

5. These disturbances in the magnetic field of the transducer give rise to current signals in the winding 12, which current signals may be processed and amplified to provide sound. The nature of the winding 12 around the core 11 may be varied to obtain different results. For example, a winding of 5.5KΩ would provide a very high frequency transducer with the resulting sound produced by the guitar having a tight bass range of frequencies and very little in the middle range of frequencies. However, a winding of 7KΩ would give a very high output, there being a good high and low frequency response with mimmal mid range.

The laminated core 11 reduces the effect of eddy currents in the transducer, as it would in a conventional transformer. However, an additional benefit of the laminated core is that it results in a high magnetic apex field. The effects of this in a guitar are that an extended range of frequencies are sensed by the magnetic field of the transducer and also the guitar's sound possesses added clarity. An advantage of using a heavy winding, such as high-carbon copper in the above described embodiment, is that relatively few turns of wire are needed to produce an effective transducer.

Ceramic magnets are chosen because of their strength in relation to their size. The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiments). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. An electromagnetic transducer for a musical instrument, having a core and at least one insulated conductive winding wound around said core; characterised in that said core is fabricated from a plurality of laminations.

2. An electromagnetic transducer according to Claim 1, characterised in that said laminations are molecularly aligned steel plates.

3. An electromagnetic transducer according to Claim 1 or Claim 2, characterised in that said core is fabricated from between 3 and 30 laminations.

4. An electromagnetic transducer according to any of the Claims 1 to 3, characterised in that said at least one conductive winding is of insulated copper wire.

5. An electromagnetic transducer according to Claim 4, characterised in that said copper wire is between 0.04mm and 0.10mm in diameter.

6. An electromagnetic transducer according to any of Claims 1 to 5, characterised in that a magnetic field is created around and through said core.

7. An electromagnetic transducer according to Claim 6, characterised in that said magnetic field passes through said core in a direction substantially parallel to said laminations.

8. An electromagnetic transducer according to Claim 6 or Claim 7, characterised in that said magnetic field is created by a pair of magnets placed along side said core.

9. An electromagnetic transducer according to Claim 8, characterised in that said magnets are ceramic magnets.

10. An electromagnetic transducer, comprising at least two ceramic magnets and a portion of high carbon copper wire; the high carbon copper wire being operatively wound around a core, said core having a plurality of laminations; wherein said ceramic magnets are operatively positioned with respect to the core, such that at least some lines of flux extending from said magnets pass through the core and extend substantially parallel to at least one of the laminations.

11. An electromagnetic transducer substantially as described herein with reference to the accompanying drawings.

12. An electric guitar having an electromagnetic transducer according to any of Claims 1 to 10.