Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
STEREO HEADSET WITH NOISE SUPPRESSION
FIELD OF THE INVENTION
The invention relates to a headset for enjoying audio sounds and in particular
to
a stereo headset for enjoying high fidelity audio sound signals, incorporating
stereophonic speakers and signal separation components and electronic noise
reduction circuits in both sides of the headset.
BACKGROUND OF THE INVENTION
Headsets for listening to audio signal sounds have been available since almost
as early
as the invention of radio, or morse code. Most headsets simply incorporate a
simple
miniature speaker in each side. Each speaker -eceives exactly the same audio
signal
and attempts to reproduce the signal in both sides simultaneously. Generally
speaking
the quality of such miniaturized speakers is not as great as could be desired.
The
speakers receive audio signals containing the full spectrum of wave lengths
from low to
high. It has been considered to be impractical to incorporate speakers similar
to full
size speaker systems which incorporate two or three speakers, and a cross over
circuit,
which systems can then reproduce high, medium and low frequencies in a
stereophonic
manner. Cross over circuits could only be desk,.;ned with difficulty in such
headsets.
Even with such a cross-over there would still be noise signals generated in
the circuit.
Clearly it is desirable from the viewpoint of both clarity, and also enjoyment
of the
quality of the sound signals, that sounds shall be reproduced in such headsets
in a
stereophonic manner. Preferably such result will be achieved by providing a
headset
which is of compact design and not excessively large or cumbersome. In
addition, it is
desirable to provide such a system which can be made in an economical manner,
and
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which is as far as possible free from servicing problems, which might result
from
providing multiple frequency speakers in opposite sides of a headset. It is
well known
that the fidelity of simple speakers is impaired by the development of
electronic noise
signals generated in the speaker coils themselves. Clearly it is desirable if
possible to
provide a headset with stereophonic speaker systems for each ear and in which
the
signal separation circuits incorporate circuits which reduce or substantially
eliminate the
electronic noise generated within the circuits, so as to greatly increase the
clarity of
reproduction.
BRIEF SUMMARY OF THE INVENTION
With a view to providing a headset, having ear phones for respective ears, and
reproducing audio signals in a stereophonic manner, the invention comprises:
two ear components; a head band connected between the two ear components, by
which the two ear components can be fitted over the ears; a hi frequency
speaker and a
low frequency speaker in each ear component; a signal separator circuit in
each ear
component; and, two bifilar noise reduction coil assemblies in each ear
component.
Preferably, the invention provides such a head set, wherein there are two such
speakers namely a high frequency speaker and a low frequency speaker in each
ear
component, and a respective noise reduction assembly in respective ear
component
which effectively suppress electronic noise developed in the system.
Preferably the invention further provides such a head set wherein the high
frequency
speaker and the low frequency speaker are secured on a common mounting plate,
and
in which the common mounting plate is secured to the interior of the headset
itself.
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Preferably, the invention provides such a headset in which the mounting plate
defines a
central opening and a series of radial arms extending inwardly and supporting
an inner
mounting disc, and wherein the high frequency speaker is mounted on the
mounting
disc on one side of the mounting disc, and wherein the low frequency speaker
is
mounted on the opposite side spaced from the high frequency speaker.
Preferably the invention provides a circuit support member separate from the
mounting
plate wherein the noise reduction and signal separation circuit is mounted on
the
support member.
Preferably each ear phone has a shell defining a hollow space behind the low
frequency speaker...
The various features of novelty which characterize the invention are pointed
out
with more particularity in the claims annexed to and forming a part of this
disclosure.
For a better understanding of the invention, its operating advantages and
specific
objects attained by its use, reference should be made to the accompanying
drawings
and descriptive matter in which there are illustrated and described preferred
embodiments of the invention.
IN THE DRAWINGS
Figure 1 is a perspective illustration of a typical headset illustrating the
invention;
Figure 2 is an exploded view of one ear component of Figure 1;
Figure 3a is a perspective of a bifilar coil noise reduction and signal
separator, in a
protective housing;
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Figure 3b is an end elevation of Figure 3b;
Figure 3d is a side elevation of Figure 3b;
Figure 3e is a circuit diagram of the separator circuit;
Figure 4 is a schematic diagram showing the arrangement of a bifilar coil; and
Figure 5 is a side elevation of a bifilar coil, partly cut away.
DESCRIPTION OF A SPECIFIC EMBODIMENT
The following detailed description is merely exemplary in nature and is not
intended to
limit the described embodiments or the application and uses of the described
embodiments. As used herein, the word "exemplary" or "illustrative" means
"serving as
an example, instance, or illustration." Any implementation described herein as
"exemplary" or "illustrative" is not necessarily to be construed as preferred
or
advantageous over other implementations. All of the implementations described
below
are exemplary implementations provided to enable persons skilled in the art to
make or
use the embodiments of the disclosure and are not intended to limit the scope
of the
disclosure, which is defined by the claims. For purposes of description
herein, the
terms 'upper", "lower", "left", "rear", "right", "front", "vertical",
"horizontal", and derivatives
thereof shall relate to the examples as oriented in the drawings. Furthermore,
thereis
no intention to be bund by an expressed or implied theory presented in the
preceding
technical field, background, brief summary or the following detailed
description. It is
also to be understood that the specific devices and processes illustrated in
the attached
drawings, and described in the following specification, are simply exemplary
embodiments (examples), aspects and / or concepts defined in the appended
claims.
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Hence, specific dimensions and other physical characteristics relating to the
embodiments disclosed herein are not to be considered as limiting, unless the
claims
expressly state otherwise. It is understood that "at least one" is equivalent
to "a".
Referring first of all to Figure 1, it will be seen that this illustrates what
appears to
be at first sight to a conventional headset, having two ear phone components
(10 and
12) , and a resilient band (14) connecting the two ear components and a wire
harness
(16) , which would be adapted to be connected to a source of audio signals
(not
shown). The resilient band (14) is flexible, and permits the two ear
components (10 &
12) to be spread apart and fitted over the head. The resilient band (14)
incorporates
sliders (18) which enable the user to extend the band or retract it, depending
upon the
size of the head. Each of the ear components (10 & 12) is substantially
identical
with its main components being similar.
Thus each ear component has a housing shell (20) (Fig 2) supported in a
generally
semi circular shaped spring support (22). Studs (24) engage recesses (26).
Supports
(22) are connected to the resilient band (14). The shell (20) is of generally
cup shaped
formation, typically being formed of thermo plastic material in known manner.
A wire
harness opening (28) (in one shell) permits wire harness (16) to enter the
shell. Shell
(20) has an oval shape and a circumferential rim (29).
A hole (30) is formed in shell (20), for reasons to be described .below.
A harness extension wire (32) (Fig 1) extends from the one shell, around the
resilient
band (14), and in to the opposite shell.
Each ear component (10 & 12) is as explained above, substantially identical,
although
with minor variations. Accordingly only the contents of one such ear component
will be
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described, it being understood that the same components will be contained in
the
opposite component.
Within the shell (20), an annular circuit support member (34) is secured by
screws (36),
received in suitable screw receiving recesses in the shell. The support member
(34)
has a collar (38 ) formed thereon, around an opening, and a notch (40) is
formed in the
collar (38). Collar (38) forms a funnel, allowing low frequency sound waves to
flow in
and out of the shell (20).
A speaker mounting plate (42) is provided, which will also be secured by
screws (36).
Speaker mounting plate (42 ) defines a central opening and has a spider
formation
defining spokes (44) and a central support ring (46). A high frequency speaker
(48) is
mounted on the forward side of the ring (46) and faces forwardly . A low
frequency
speaker (50) is mounted adjacent the rearward side of plate (42) and faces
reawardly
Both speakers define central axes which are aligned with one another
Forward and rearward simply refer to delivery of sound to the ear of the user.
An annular ear pad (52) , encloses the exterior of the circuit support member
( 34) and
the speaker mounting plate (42) and fits directly over the rim (29) of the
shell (20) . The
pad is typically made of resilient soft material The high frequency speaker
(48) and the
low frequency speaker ( 50) are connected to a noise reduction and signal
separator
circuit (54). The circuit (54 ) is secured in the notch (40) by a screw.
The circuit (54) has a housing (56) (Fig 3), and a circuit board (58), held
together by
means of screw (60). Each circuit board (58 ) supports noise reduction
assemblies
namely a low frequency bifilar coil (62) and a high frequency bifilar coil
(64). Each
circuit board also supports a high frequency input capacitor ( 66) and high
frequency
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return capacitor (68).
It will be understood from the following explanation that bifilar coils are
coils which are
two lengths of wire, wound together side by side, carrying signals in the same
direction.
Bifilar coils are described in U.S. Patents:
11/260,458 (pending ; 08/555,187 - Patent 5615272; 08/784,065 - Patent
5917922;
07/917985 - Patent 5373563;
Such a bifilar coil is illustrated in Figures 4 and 5.
As will be seen from Figure 4, a bifilar coil is two lengths of wire, which
have been
wound together side by side on a common core forming an input coil (IC) and a
return
coil (RC).
Figure 5 merely illustrates the way in which the input and return coils are
wound
together, with the windings of the two coils being side by side on a common
core.
The input coil is connected to receive the input signal from the signal
source. The
signal passes through the input coil (IC) and then into the speaker (Sp) and
then
returns from the speaker to the return coil (RC) and then to ground. It will
thus be seen
that the signals pass through both the input coil and the return coil in the
same
direction. However the return signal will be slightly delayed relative to the
input signal
due to its passage through the speaker coil. This ensures that the unwanted
electromagnetic fields created by the passage of the signals through the
speaker and
the two coils are substantially suppressed thus reducing electronic noise.
For the sake of simplicity the circuit board illustration , (Figure 3e),
illustrates what
appear to be four separate coils namely a low frequency input coil (62a) and a
low
frequency return coil (62b), and a high frequency input coil (64a) and a high
frequency
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return coil (64b). In fact however, the coils form two bifilar coils
illustrated in Figures
3b, 3c and 3d namely low frequency bifilar coil (62) and high frequency
bifilar coil (64).
The design of the circuit board ( Fig 3e) is of such a compact nature that the
entire
circuits consisting of high frequency bifilar coil and low frequency bifilar
coil and the two
capacitors can all be contained within a housing (56) (Figure 3d.)
It will be noted that the two bifilar coils (62, 64) are secured to the board,
with their
central axes lying parallel to the board. This provides for secure attachment
of each
coil at each end, thereby ensuring that the coils remain securely fastened
notwithstanding the development of electromagnetic fields around them.
On the other side the two capacitors are supported on the board on end, so
that their
central axes are normal to the board, thereby enabling the provision of the
circuit which
is compact and easily contained within the housing and secured within the
interior of
each ear component.
The function of the capacitors in the high frequency side of the circuit is
simply to block
the incoming low frequency signals from passing through the high frequency
bifilar
coils (64). This provides effective separation of the high frequencies from
the low
frequencies.
An annular flexible resilient pad (52 ) is provided and adapted to rest
against the head
of the wearer around the ear. In this way, extraneous exterior sounds are
reduced or
excluded as far as possible.
The operation of the foregoing circuits is believed to be self evident and
proceeds by
the supply of a regular audio signal to wire harness (16 ) and to the first
ear component.
The signal is communicated to the second ear component by the harness
extension
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(32). The operation in both ear components is the same.
The input signal is supplied to the circuit board (58)( Fig 3e) and is
communicated to
the input side (62a) of the respective low frequency bifilar coil (62 ) and
the input side
(64a) of the high frequency bifilar coil (64). The signals from the input side
(62a) of the
low frequency bifilar coil (62), pass directly to the speaker (50).
From the speaker (50 ) the low frequency signals pass back through the return
side
(62b) of the low frequency bifilar coil (62) and to ground.
The signals from the input side (64a) of the high frequency bifilar coil (64),
pass
through input capacitor (66) to the speaker ( 48)
The high frequency signals, after passing through the speaker (48 ) pass back
to the
return capacitor (68 ) and then through the return side (64b) of the high
frequency bifilar
coil (64), and then to ground.
As the sounds in the low frequency speaker (50) are reproduced, low frequency
sounds
will flow rearwardly ie. away from the ear of the user, into the hollow space
of the shell
where the sounds can reverberate and develop full volume and will then flow
back
through the funnel defined by the collar. They will pass around the spokes
(44), around
the high frequency speaker (48) and into the ears of the user. The high
frequency
sound signals reproduced in the high frequency speaker (48) will pass directly
to the
ear of the user. The net result is a great increase in clarity, since the low
frequency
sounds and high frequency sounds are reproduced in separate speakers,
resulting in
three-dimensional sound.
The resulting sounds will be considerably amplified in comparison with the
sounds
generated by conventional circuits and speakers. This is because the sound
waves as
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they pass through their respective bifilar coils, are formed into regular wave
forms with
abrupt definition.
In addition the noise signals normally produced by audio signals passing
through
speaker coils at the lower frequencies will be greatly reduced, by the
cooperation of the
input and return sides of the low frequency bifilar coil with one another.
Similarly, the
noise normally created by the high frequency signals going the through speaker
coil,
although of a less aggravating nature than the low frequency noise signals,
will also be
greatly reduced by passage of the high frequency signals through the high
frequency
bifilar coils.
The shell (20) provides a chamber in which the low frequency sounds can
resonate.
The hole (30) functions to allow greater resonation. This result is a greater
volume and
greater clarity of sound. The sounds are not merely stereophonic, but, since
they are
communicated to each ear simultaneously, the sound appears to surround the
listener.
The hole (30) can optionally be covered over (eg. by tape) if the user desires
less low
frequency or bass sound development.
The foregoing is a description of a preferred embodiment of the invention
which is given
here by way of example only. The invention is not to be taken as limited to
any of the
specific features as described, but comprehends all such variations thereof as
come
within the scope of the appended claims.
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