GB2093591A - Electronic magnetic compass using hall effect sensor - Google Patents

Abstract

A Hall-signal probe 2 detects the direction and orientation of a magnetic field especially that of the earth. The magnetic field is concentrated onto and around the Hall-signal probe by shaped pole pieces 1 of high permeability, low reluctance materials such as silicon ferrite. The voltage induced in the Hall- signal probe is amplified so that it can activate audio, audio-visual, visual or other electrically activated devices to indicate the direction and orientation of the magnetic field. <IMAGE>

Description

SPECIFICATION Electronic compass I Richard Michael Kerslake of 21 Compton Road Shepton Mallet Somerset do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is performed to be accurately described in and by the following statement.

The present invention relates generally to the use of a Hall-signal probe to detect the direction and orientation of a magnetic field. More particularly this invention is concerned with the detection of the earth's magnetic field. The magnetic field induces a small voltage in the Hall-signal probe.

The magnetic field can be concentrated onto and around the Hall-signal probe by suitable devices, for example shaped ferromagnetic materials, and in particular those of high permeability and low reluctance. The shape and use of these materials gives the compass described herein good vertical stability and makes the instrument less sensitive to the inclination of the compass and the angle of dip of the earth's magnetic field. The invention described in this application requires no dampening devices nor elaborate mechanisms associated with existing compasses.

As the invention is an electromagnetic device it is possible to use visual, audio, audiovisual or other means of indication which can be activated by an electric current or potential. With appropriate design of electronic amplification and electrical power source the electronic compass described can be made in a compact robust form suitable for use by walkers and for use in small boats, dingies and light aeroplanes.

Indication of the magnetic field's orientation and direction can be made by a changing audible pitch or amplitude thus eliminating the need for the user to be able to see the invention described herein. The indication can also be by electrically activated lightemitting or liquid crystal devices which can be different in shape, size, colour number or position which would be visible irrespective of the general lighting conditions.

The number of indicating devices operated by the Hall-signal probe can be one or more depending on the design of the electronic amplifier used.

Example The Hall-signal probe (Siemens SU230S) (2) is mounted between the two high permeability, low reluctance silicon ferrite pole pieces (1) shaped as in Figure 1 at right-angles to the plane of the pole pieces as in Figure 2.

The electronic circuit used in the solid state compass is shown in Figure 4. The circuit boards (15) containing the circuits are mounted in the slots (4) in the support disc (3) on either side of the pole-pieces/ Hall-signal probe assembly. See Figure 3. The holes (6) in the support disc enable wires to pass to the rechargeable Nickel-Cadmium batteries (7) and the on/off switch (10). The rechargeable batteries (7) are housed in the lower portion of the body (8) and can be connected to an external power supply by terminals (9) in the base of the body (11). See Figure 5. The light-emitting diodes (13) are sited in the upper body (12) which can be rotated under a perspex cover (14) marked in degrees.

As the compass is rotated relative to the magnetic field the potential induced in the Hall-signal probe changes from positive to negative when the polepieces/Hall signal probe is perpendicular to the magnetic field. This change is used to switch one light-emitting diode off and another on.

1. The use of a Hall-signal probe to detect the direction and orientation of a magnetic field.

2. The use of that claimed in 1 to detect the direction and orientation of the earth's magnetic field.

3. The use of high permeability, low reluctance materials to concentrate the magnetic field onto and around the Hall-signal probe when used as claimed in 1 and 2.

4. The use of that claimed in 1 and 2 with or without that claimed in 3 to activate audio, audiovisual visual or otherer on.

CLAIMS 1. The use of a Hall-signal probe to detect the direction and orientation of a magnetic field.

2. The use of that claimed in 1 to detect the direction and orientation of the earth's magnetic field.

3. The use of high permeability, low reluctance materials to concentrate the magnetic field onto and around the Hall-signal probe when used as claimed in 1 and 2.

4. The use of that claimed in 1 and 2 with or without that claimed in 3 to activate audio, audio

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electronic compass I Richard Michael Kerslake of 21 Compton Road Shepton Mallet Somerset do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is performed to be accurately described in and by the following statement. The present invention relates generally to the use of a Hall-signal probe to detect the direction and orientation of a magnetic field. More particularly this invention is concerned with the detection of the earth's magnetic field. The magnetic field induces a small voltage in the Hall-signal probe. The magnetic field can be concentrated onto and around the Hall-signal probe by suitable devices, for example shaped ferromagnetic materials, and in particular those of high permeability and low reluctance. The shape and use of these materials gives the compass described herein good vertical stability and makes the instrument less sensitive to the inclination of the compass and the angle of dip of the earth's magnetic field. The invention described in this application requires no dampening devices nor elaborate mechanisms associated with existing compasses. As the invention is an electromagnetic device it is possible to use visual, audio, audiovisual or other means of indication which can be activated by an electric current or potential. With appropriate design of electronic amplification and electrical power source the electronic compass described can be made in a compact robust form suitable for use by walkers and for use in small boats, dingies and light aeroplanes. Indication of the magnetic field's orientation and direction can be made by a changing audible pitch or amplitude thus eliminating the need for the user to be able to see the invention described herein. The indication can also be by electrically activated lightemitting or liquid crystal devices which can be different in shape, size, colour number or position which would be visible irrespective of the general lighting conditions. The number of indicating devices operated by the Hall-signal probe can be one or more depending on the design of the electronic amplifier used. Example The Hall-signal probe (Siemens SU230S) (2) is mounted between the two high permeability, low reluctance silicon ferrite pole pieces (1) shaped as in Figure 1 at right-angles to the plane of the pole pieces as in Figure 2. The electronic circuit used in the solid state compass is shown in Figure 4. The circuit boards (15) containing the circuits are mounted in the slots (4) in the support disc (3) on either side of the pole-pieces/ Hall-signal probe assembly. See Figure 3. The holes (6) in the support disc enable wires to pass to the rechargeable Nickel-Cadmium batteries (7) and the on/off switch (10). The rechargeable batteries (7) are housed in the lower portion of the body (8) and can be connected to an external power supply by terminals (9) in the base of the body (11). See Figure 5. The light-emitting diodes (13) are sited in the upper body (12) which can be rotated under a perspex cover (14) marked in degrees. As the compass is rotated relative to the magnetic field the potential induced in the Hall-signal probe changes from positive to negative when the polepieces/Hall signal probe is perpendicular to the magnetic field. This change is used to switch one light-emitting diode off and another on. CLAIMS

1. The use of a Hall-signal probe to detect the direction and orientation of a magnetic field.

2. The use of that claimed in 1 to detect the direction and orientation of the earth's magnetic field.

3. The use of high permeability, low reluctance materials to concentrate the magnetic field onto and around the Hall-signal probe when used as claimed in 1 and 2.

4. The use of that claimed in 1 and 2 with or without that claimed in 3 to activate audio, audio

4. The use of that claimed in 1 and 2 with or without that claimed in 3 to activate audio, audiovisual visual or otherer on.

1. The use of a Hall-signal probe to detect the direction and orientation of a magnetic field.

2. The use of that claimed in 1 to detect the direction and orientation of the earth's magnetic field.

3. The use of high permeability, low reluctance materials to concentrate the magnetic field onto and around the Hall-signal probe when used as claimed in 1 and 2.