Transmitter with Improved Sensitivity and Shielding

• US 20140087659A1
• Filed: 03/12/2013
• Published: 03/27/2014
• Est. Priority Date: 08/29/2012
• Status: Active Grant

• Current Assignee: Red Tail Hawk Corporation
• Original Assignee: Red Tail Hawk Corporation
• Inventors: Parkins, John W.
• Granted Patent: US 9,083,388 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: A61F 11/08 internal, e.g. earplugs
• CPC Class Codes: H01Q 1/2291 used in bluetooth or WI-FI devices of Wireless Local Area Networks [WLAN] H01Q1/241 takes precedence; WLAN in general H04W
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 7/06 with core of ferromagnetic material H01Q7/02 takes precedence
• CPC Class Codes: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04R 1/1008 Earpieces of the supra-aural or circum-aural type
• CPC Class Codes: H04R 1/1075 Mountings of transducers in earphones or headphones
• CPC Class Codes: H04R 1/1091 Details not provided for in groups H04R1/1008 - H04R1/1083
• CPC Class Codes: H04R 2209/022 Aspects regarding the stray flux internal or external to the magnetic circuit, e.g. shielding, shape of magnetic circuit, flux compensation coils
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones
• CPC Class Codes: H04R 25/554 using a wireless connection, e.g. between microphone and amplifier or using Tcoils

Abstract

A magnetic field transmitter, especially a transmitter used in conjunction with wireless communications earplugs. In one embodiment, a plate of magnetic material is used behind a coil of electrical conductor to improve the efficiency of the transmitter and to provide electrical and magnetic shielding. The specific dimensions and characteristics of the preferred embodiment of the transmitter described herein provide for efficient wireless communications.

Claims

1. A magnetic field transmitter generating a time varying magnetic field in response to a time varying input signal, comprising:

a) a transmitter coil winding constructed of continuous conductor loops, having an inner perimeter and outer perimeter separated by a distance;

a coil winding resistance and coil winding inductance;

b) said inner perimeter circumscribing an effective coil area between 0.79 in² and 4.9 in²; and

c) said resistance and inductance producing a break frequency between 20 Hz and 2000 Hz.

2. The magnetic field transmitter of claim 1 further comprising a magnetic backing plate having an upper surface and lower surface held in close proximity to the coil winding lower surface, said backing plate having an outer perimeter that is approximately coincident with the coil winding outer perimeter.

3. The magnetic field transmitter of claim 2 where the backing plate is perforated with at least one perforation.

4. The magnetic field transmitter of claim 2 where the magnetic backing plate is cup-shaped, comprising a rim with an inner surface and outer surface, said inner surface formed in close proximity to the coil winding outer perimeter, extending from the backing plate upper surface to the coil winding upper surface.

5. The magnetic field transmitter of claim 2, in which the magnetic backing plate is grounded.

6. The magnetic field transmitter of claim 1, in which the coil has an upper surface and lower surface separated by a distance, L2, further comprising a magnetic core substantially filling a volume defined by the coil winding inner perimeter and L2.

7. The magnetic field transmitter of claim 6, where the core is perforated with at least one perforation.

8. The magnetic field transmitter of claim 6, in which the magnetic core is grounded.

9. The magnetic field transmitter of claim 1, further comprising an integrated audio acoustic speaker to produce an acoustic output from said input signal.

10. The magnetic field transmitter of claim 1, further comprising a wireless ear plug communications device magnetically coupled with said magnetic field transmitter to produce an acoustic output from said input signal at said earplug.

11. The magnetic field transmitter of claim 1, in which the loops of the transmitter coil winding are circular.

12. A magnetic field transmitter generating a time varying magnetic field in response to a time varying input signal, comprising:

a) a transmitter coil winding constructed of continuous conductor loops, having an inner perimeter and outer perimeter separated by a distance;

a coil winding resistance and coil winding inductance; and

b) a magnetic backing plate having an upper surface and lower surface held in close proximity to the coil winding lower surface, said backing plate having an outer perimeter that is approximately coincident with the coil winding outer perimeter.

13. The magnetic field transmitter of claim 12, in which said inner perimeter circumscribing an effective coil area between 0.79 in² and 4.9 in².

14. The magnetic field transmitter of claim 12, in which said resistance and inductance produce a break frequency between 20 Hz and 2000 Hz.

15. The magnetic field transmitter of claim 12 where the backing plate is perforated with at least one perforation.

16. The magnetic field transmitter of claim 12 where the magnetic backing plate is cup-shaped, comprising a rim with an inner surface and outer surface, said inner surface formed in close proximity to the coil winding outer perimeter, extending from the backing plate upper surface to the coil winding upper surface.

17. The magnetic field transmitter of claim 12, in which the magnetic backing plate is grounded.

18. The magnetic field transmitter of claim 12, in which the coil has an upper surface and lower surface separated by a distance, L2, further comprising a magnetic core substantially filling a volume defined by the coil winding inner perimeter and L2.

19. The magnetic field transmitter of claim 18, where the core is perforated with at least one perforation.

20. The magnetic field transmitter of claim 18, in which the magnetic core is grounded.

21. The magnetic field transmitter of claim 12, further comprising an integrated audio acoustic speaker to produce an acoustic output from said input signal.

22. The magnetic field transmitter of claim 12, further comprising a wireless ear plug communications device magnetically coupled with said magnetic field transmitter to produce an acoustic output from said input signal at said earplug.

23. The magnetic field transmitter of claim 12, in which the loops of the transmitter coil winding are circular.