Note: Descriptions are shown in the official language in which they were submitted.
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PRESSURE RING FOR EAR COVER
BACKGROUND OF THE INVENTION
The present invention rela~es to a pressure
ring for an ear cover, like an earmuff, earphones, or
the like product, which is designed to include a seal-
ing ring.
Known earmuffs, earphones, or the like, in-
clude an ear covering cup that is provided with a seal-
ing ring to provide tight contact against the head in
the region of the wearer's ear. The sealing ring is
supported by a flat pressure ring behind the sealing
ring. The pressure ring is in the form of a separate
ring or is an integrated part of ~he ear covering cup.
Rressure is applied on the earmuff by a headband, so
that the sealing ring and the pressure ring behind it
are elastically deformed into contacting the wearer's
head. It has been found that the contact pressure has
caused certain persons discomfort when they wear the
above described earmuffs for long periods of time. It
has also proven difficult to obtain sufficiently ti~ht
contact against the head. One solution to these prob-
lems has been to increase the thickness of the sealing
ring. But this has resulted in a deteriorated dampen-
ing effect.
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SUMM~RY OF THE INVENTION
~ . . _ _
The object of the present invention is to
eliminate the above drawbacks of known ear covers, like
earmuffs, or the like, and to provide a pressure ring
of the type described in the introduction which satis-
factorily fits against the head without causing discom-
fort or deteriorating the properties of the earmuff.
According to the invention, a pressure ring
has an arched, concave contact sur~ace to effect sub-
stantially tight contact against the head in the region
around the wearer's ear. The con~act surface has an
inner peripheral edge and an outer peripheral edge
which are located at different heights above the base
surface of the pressure ring creating the concavity.
The height of at least the outer peripheral
edge and also perhaps of the inner peripheral edge
above the base surface are suitably higher at the upper
and lower ends of the pressure ring than in the central
region of the pressure ring between those ends.
According to the invention, the pressure ring
may also be provided with a channel extending into the
pressure ring from the inside or sealing ring facing
side toward the outside of the pressure ring. This
channel runs along a substantial portion of the circum-
ference of the pressure ring. The channel suitably
runs once or several times around the pressure ring.
The channel is designed to produce one or more sound
traps.~
According to a preferred embodiment, the
channel may be comprised of a number of concentric
grooves located between the contact surface and base
surface of the sealing ring. Each of the grooves is
~Z92~
provided with a barrier blocking the groove from ex-
tending around the entire circumference of the pressure
ring and an opening connec~ing that groove to adjacent
grooves. The barrier and opening are arranged so as to
make the channel as long as possible.
Other ob]ects and features of the invention
are described with reference to the accompanying draw-
ings.
~RIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plan view of a pressure ring
according to the invention.
Fig. 2 shows a cross-section through the
pressure ring in Fig. 1.
Fig. 3 shows a cross-section through an
alternative embodiment of the pressure ring according
to the invention, also shown here schematically fitted
into an earmuff.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The Figures show two embodiments of a pres-
sure ring for an ear cover. For each embodiment, a
pressure ring 2 and a sealing ring 3 (shown in Fig. 3)
designed for an earmuff 1 (also shown in Fig. 3) are
shown. The pressure ring 2 is suitably oval in shape,
comprising an upper end 4 to the right in Fig. 1, a
lower end 5 to the left and a central region 6 between
them. The annular pressure ring 2 is provided with a
base surface 7 at its outside or bottom in Fig. 2, a
contact surface 8 at its inside or top and an outer
surface 9 beneath the base. The outer surface 9 is
provided with attachment means 10 for attaching the
base to the earmuff, cup, or the like.
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The annular pressure ring 2 also comprises a
radially inner or peripheral edge 11 at its contact
surface and a radially outer or peripheral edge 12 also
at its contact surface.
A channel 13 extends from the radial inside
of the pressure ring at an opening 14 ~o its radial
outside at a hole 15. The channel 13 may comprise con-
centric grooves 16 communicating with each other via
radially ext~nding, narrow width openings 17. Each
groove 16 is lim;ted by a barrier 18 which prevents
each groove from closing upon itself. The channel 13
may also be provided with a number of short circumfer-
ential length sound traps 19, where a groove 16 pro-
jects past a respective radial opening 17 into that
groove.
The pressure ring 2, according to the inven-
tion, may be made as a homogenous unchanneled unit, but
is preferably provided with the channel 13. From a
manufacturing point of view, this is very suitable and
also reduces the weight of the pressure ring, as com-
pared with a homogeneous one. The pressure ring 2 may
~hus suitably be produced from a plastic material by
means of injection molding. However, other materials
and fabrication methods are of course feasible.
An additional advantage of the channel 13 is
that pressure is equalized between the inside and out-
side of the earmuff. Known earmuffs are provided with
a small hole in their cup to achieve pressure equaliza-
tion. But; some sound has been found to penetrate
through the hole, deteriorating the protective quali-
ties of ~he earmuff. In the present invention, pene-
tration of sound is limited by the channel 13 being
99
-- 5 --
made as long as possible. This is achieved by the
channel 13 running along a substantial portion of the
circumference of the pressure ring 2, and preferably
around once or possibly even several times as shown in
Fig. ~. The channel may be in the form of a spiral or
zig-æag pattern. However, the embodiment shown in Fig.
1 has proven advantageous from the manufacturing point
of view and has also enabled one or more sound traps 19
to be inclùded.
The proposed channel may thus be designed
with concentric grooves 16, each having a height dimen-
s,ion in the direction between the contact surface 8 and
the base surface 7 of the sealing ring. Each of the
grooves 16 is provided with its own barrier 18 which
blocks the groove 16 and prevents it making a full cir-
cuit around the pressure ring. A radially directed
opening 17 joins the groove 16 to adjacent grooves.
The barrier 18 and opening 17 are thus substantially
arranged to make the channel 13 as long as possible.
In the embodiment shown, the barrier 18 and opening 17
have been spaced from each other in order to form a
sound trap 19 at the end of each groove lS for further
inhib;ting spreading of the sound.
A number of measurements have been performed
on several people to determine the dimensions of the
pressure ring 2 so that the contac~ surface 8 will fit
as tightly against the head as possible. It has been
found-that the topography of the head is most uniform
closest to the ear, has recesses at the temple and be-
hind the jaw which are located diagonally opposite each
other, and is raised close to the ear, and is more
prominent in women than in men. Based on these mea-
~Z92~9
-- 6 --
surements, it is possible to adjust the pressure ring
to fit the left or right ear, the upper or lower side
and also to fit for men or women. The shape of the
ring can be adjusted to the topo~raphy of the region
around the ear, thus reducing the con~act pressure
without the earmuff falling off or giving increased
dampening effect, especially by allowing the use of a
thinner ring.
According to the invention, the inner edge 11
and outer edge 12 at the contact surface 8 are located
at different levels or heights above the base surface 7
of the pressure ring. Although it is advisable to
shape the pressure ring 2 to fit the right or left ear,
from a practical point of view it may be advanta~eous
to shape the pressure rinys 2 symmetrically. To this
end, the levels or heights of the inner edge 11 and of
the outer edge 12 above the base surface 7 are located
higher at the upper and lower ends 4, 5 than at the
central region 6 of the pressure ring. This height
difference in edge 12 can be seen in Fig. 2. The
accompanying table illustrates it also. The average
height difference between the level of the inner edge
11 and the level of the outer edge 12 is 2.5 + 0.9 mm.
As a result, the pressure ring is arched or concave,
giving the sealing ring above it a concave inside sur-
face and making the surface of the ear cover against
the head concave.
To obtain the required information for shap-
ing the pressure ring around the entire ear cover, a
number of measurements were taken around the ear at a
distance corresponding to the limit of the inner edse
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and also at a distance corresponding to the limit of
the outer edge. Ten measurements were performed around
each ear and the results are shown in the following
table where U denotes the top of the ear; N denotes the
bottom of the ear; A-D denote points measured evenly
around each side of the ear; i denotes the inner mea-
surement path; and y denotes the outer measurement
path.
The sealing ring 3 for any embodiment is
shown in Fig. 3. It may be of foam plastic covered
with a non-porous protective layer. The protective
layer may also extend along the inside of the foam
plastic ring in order to increase the dampening func-
tion of the channels. The pressure ring in Fig. 3 is
of shorter height at its outer edge than that of Fig.
2.
Of course, the invention can be modified with
respect to the fit if~ for instance, measurements in
other countries give different average values. Certain
adjustments may also be required for extra equipment
such as audio headphones, walkie-talkies, etc.
Although the present invention has been de-
scribed in connection with a plurality of preferred em-
bodiments thereof, many other variations and modifica-
2S tions will now become apparent to those skilled in the
art. It is preferred, therefore, that the present in-
vention be limited not by the specific disclosure here-
in, but only by the appended claims.
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