U.S. patent number 3,593,341 [Application Number 05/000,219] was granted by the patent office on 1971-07-20 for sound-attenuating earcups.
This patent grant is currently assigned to Gentex Corporation. Invention is credited to Jackson A. Aileo.
United States Patent |
3,593,341 |
Aileo |
July 20, 1971 |
SOUND-ATTENUATING EARCUPS
Abstract
A sound-attenuating earcup device adapted for use either with or
without a safety helmet, comprising a rigid cup with a resilient
seal attached to the rim of the cup. The seal has an annular
surface for engaging the wearer's head, and has a dimension between
the cup rim and the outermost head-engaging portion of this surface
that varies around the periphery of the cup in accordance with the
contours of a human head. In one form, the surface of the seal
which comes into contact with the wearer's head includes inner and
outer flanges defining a channel having diverging side flanges.
When the seal is pressed into engagement with the side of the
wearer's head, the flanges spread apart and the material between
the flanges is stressed in tension, thereby improving the
effectiveness of the seal at the flanges and, hence, the
sound-attenuating properties. The outer flange is contoured to
follow the contours of a human head. A tortuous,
pressure-equalizing, sound-attenuating fluid path is provided
through the wall of the earcup, for use in situations where the
ambient pressure is subject to variation. In another form, the seal
has a wide contact surface arranged to engage the wearer's head
essentially continuously between its outer and inner annular edges;
the contact surface, which may be smooth or corrugated, slopes
inwardly toward the center of the earcup with a pitch that varies
around the cup to follow the head contours.
Inventors: |
Aileo; Jackson A. (Carbondale,
PA) |
Assignee: |
Gentex Corporation (Carbondale,
PA)
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Family
ID: |
21690462 |
Appl.
No.: |
05/000,219 |
Filed: |
January 2, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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730264 |
May 20, 1968 |
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Current U.S.
Class: |
2/209;
381/372 |
Current CPC
Class: |
A42B
3/166 (20130101) |
Current International
Class: |
A42B
3/04 (20060101); A42B 3/16 (20060101); A42b
001/06 () |
Field of
Search: |
;2/209,174,6,3,8
;128/152 ;179/156,182 ;181/31,23 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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796,004 |
|
Jan 1936 |
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FR |
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1,341,336 |
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Sep 1963 |
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FR |
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Primary Examiner: Franklin; Jordan
Assistant Examiner: Krizmanich; George H.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of applicant's copending
U.S. Pat. application, Ser. No. 730,264, filed May 20, 1968 now
abandoned for Sound-Attenuating Earcups.
Claims
I claim:
1. An earcup adapted to be pressed against the head of a wearer in
surrounding relation to the wearer's ear, including
a. a rigid cup-shaped shell with a rim having an elliptically
annular plane surface facing away from said shell and defining an
elliptically annular opening into the shell interior, dimensioned
to surround the wearer's ear;
wherein the improvement comprises:
b. a softly resilient sound-attenuating pad adapted for engagement
with the head of a wearer along an area encircling the wearer's
ear, comprising:
i. an elliptically annular base having one side secured to said
shell rim and engaging said plane surface, and
ii. an elliptically annular sealing portion projecting from the
base in a direction away from said one side, and having a sealing
surface for engaging the wearer's head with elliptically annular
outer and inner peripheries surrounding said opening and being
spaced apart substantially equidistantly from each other at all
points around the periphery of said opening, said sealing portion
having a dimension between the rim-engaging base and said sealing
surface outer periphery which varies around the periphery of the
earcup, said dimension increasing toward the front from the top to
a first maximum in the front portion of said sealing surface outer
periphery, then decreasing gradually to a minimum adjacent the
bottom, then increasing upwardly toward the back to a maximum in
the rear portion of said sealing surface outer periphery and then
decreasing gradually to another minimum adjacent the top.
2. An earcup as defined in claim 1, wherein said sealing surface
includes an elliptically annular channel disposed between said
outer periphery and said inner periphery thereof, and said sealing
portion comprises outer and inner flanges respectively projecting
radially outward and radially inward with respect to the axis of
said shell, and said outer and inner peripheries of said sealing
surface respectively comprising head-engaging surfaces of said
outer and inner flanges.
3. An earcup as defined in claim 1, wherein said sealing surface
extends substantially rectilinearly from any given point on said
outer periphery thereof to the nearest adjacent point on said inner
periphery thereof.
4. An earcup as defined in claim 3, wherein said sealing surface
slopes inwardly with respect to the axis of said shell, toward said
opening, with a pitch that varies smoothly and continuously around
the periphery of the earcup between maxima and minima respectively
positioned at the localities of said maxima and minima of the
sealing portion dimension between the rim-engaging base and said
sealing surface outer periphery.
5. An earcup as defined in claim 1, wherein said sealing portion
has a dimension between the rim-engaging base and said sealing
surface inner periphery such that at each said minimum sealing
portion dimension between said rim-engaging base and said sealing
surface outer periphery, said sealing surface outer periphery is
spaced at least as far from the rim-engaging base as is the nearest
adjacent point on said sealing surface inner periphery, and every
other point on said outer periphery is spaced farther from the
rim-engaging base than is said sealing surface inner periphery.
6. An earcup adapted to be pressed against the head of a wearer in
surrounding relation to the wearer's ear, including
a. a rigid cup-shaped shell with a rim having an elliptically
annular plane surface facing away from said shell and defining an
elliptically annular opening into the shell interior, dimensioned
to surround the wearer's ear;
wherein the improvement comprises:
b. a softly resilient sound-attenuating pad adapted for engagement
with the head of a wearer along an area encircling the wearer's
ear, comprising:
i. an elliptically annular base having one side secured to said
shell rim and engaging said plane surface, and
ii. outer and inner elliptically annular flanges projecting from
the base in a direction away from said one side, said flanges
surrounding said opening and being spaced apart substantially
equidistantly from each other at all points around the periphery of
said opening, said outer and inner flanges respectively projecting
in a radially outward direction and in a radially inward direction
with respect to the axis of said shell, so that said flanges are
deflected from their respective unstressed positions when in
engagement with the wearer's head, said flanges defining between
them a channel which is stressed in tension by said deflection of
said flanges so as to hold the flanges firmly but lightly against
the wearer's head, said flanges having smooth rounded contours, the
surface of said channel extending in a smooth continuous curve from
said outer flange to said inner flange, and said outer flange has a
head-engaging surface and a dimension between the rim-engaging base
and said head-engaging surface which varies around the periphery of
the earcup, said dimension increasing rapidly toward the front from
a first minimum at the top to a first maximum in the front portion
of said outer flange, then decreasing gradually to a minimum at the
bottom, then increasing gradually upwardly toward the back to a
maximum about two-thirds of the way to the top and then decreasing
gradually to another minimum at the top.
7. An earcup as defined in claim 6, wherein said inner flange has a
head-engaging surface and a dimension between the rim-engaging base
and said head-engaging surface of said inner flange which is
substantially constant around the periphery of said opening and is
less than the corresponding dimension of said outer flange at every
point around the periphery of said earcup.
8. An earcup as defined in claim 6, wherein the improvement further
comprises means for equalizing the pressure inside the earcup with
the external pressure, said pressure-equalizing means including a
grommet of resilient material inserted in an aperture in said
shell, said grommet having a helically threaded hole extending
therethrough from the inside to the outside of the shell, and a
helically threaded spool within said hole, the helical threads on
the spool loosely fitting the threads on the grommet so as to
provide a tortuous open passage of small cross section for flow of
air between the inside and outside of said shell, said passage
being effective to equalize pressure inside and outside the shell
and to attenuate sound waves passing therethrough from the outside
to the inside of the shell.
9. An earcup as defined in claim 6, wherein said base is hollow,
defining an elliptically annular chamber.
10. An earcup as defined in claim 6, wherein said channel includes
a third elliptically annular flange with smoothly rounded contours
intermediate said outer and inner flanges and projecting from said
channel in a direction away from said rim-engaging side of said
base.
11. An earcup as defined in claim 6, wherein said shell rim
comprises an elliptically annular discrete rigid rim member mounted
on the edge of said shell, and wherein said pad further includes an
annular flap projecting from said base in a direction away from
said outer and inner flanges and overlying the junction between
said rim member and said shell.
12. An earcup as defined in claim 11, wherein said rim member
includes an annular lip projecting outwardly from the edge of said
shell, and further including an annular resilient member including
a helical spring carried by said flap and adapted to surround and
grip the outer surface of said shell on the side of said lip away
from the wearer's head to retain said pad in position on said shell
rim.
13. A softly resiliently sound-attenuating pad adapted to be
secured to an elliptically annular rim of a rigid earcup shell for
engagement with the head of a wearer along an area encircling the
wearer's ear, wherein said rim defines an opening dimensioned to
surround the wearer's ear, said pad comprising:
a. an elliptically annular base having one side adapted to be
secured to said shell rim in engagement with an elliptically
annular plane surface thereof; and
b. outer and inner elliptically annular flanges projecting from the
base in a direction away from said one side, said flanges
surrounding said opening and being spaced apart substantially
equidistantly from each other at all points around the periphery of
said opening, said outer and inner flanges respectively projecting
in a radially outward direction and in a radially inward direction
with respect to the axis of said shell, so that said flanges are
deflected from their respective unstressed positions when in
engagement with the wearer's head, said flanges defining between
them a channel which is stressed in tension by said deflection of
said flanges so as to hold the flanges firmly but lightly against
the wearer's head, said flanges having smooth rounded contours, the
surface of said channel extending in a smooth continuous curve from
said outer flange to said inner flange, said outer flange having a
head-engaging surface and a dimension between the rim-engaging base
and said head-engaging surface which varies around the periphery of
the earcup, said dimension increasing rapidly toward the front from
a first minimum at the top to a first maximum in the front portion
of said outer flange, then decreasing gradually to a minimum at the
bottom, then increasing gradually upwardly toward the back to a
maximum about two-thirds of the way to the top and then decreasing
gradually to another minimum at the top.
14. An earcup adapted to be pressed against the head of a wearer in
surrounding relation to the wearer's ear, including
a. a rigid cup-shaped shell with a rim having an elliptically
annular plane surface facing away from said shell and defining an
elliptically annular opening into the shell interior, dimensioned
to surround the wearer's ear;
wherein the improvement comprises:
b. a softly resilient sound-attenuating pad adapted for engagement
with the head of a wearer along an area encircling the wearer's
ear, comprising
i. an elliptically annular base having one side secured to said
shell rim and engaging said plane surface, and
ii. an elliptically annular sealing portion projecting from the
base in a direction away from said one side, and having a sealing
surface for engaging the wearer's head with elliptically annular
outer and inner peripheries surrounding said opening and being
spaced apart substantially equidistantly from each other at all
points around the periphery of said opening, said sealing surface
being adapted to engage the wearer's head substantially
continuously at all points between said outer and inner peripheries
and extending substantially rectilinearly between any given point
on said outer periphery thereof to the nearest adjacent point on
said inner periphery thereof, said sealing portion having a
dimension between the rim-engaging base and said sealing surface
outer periphery which varies around the periphery of the earcup,
said dimension increasing toward the front from the top to a first
maximum in the front portion of said sealing surface outer
periphery about one-third of the way to the bottom, then decreasing
gradually to a minimum just forwardly of the bottom, then
increasing upwardly toward the back to a maximum about one-third of
the way to the top and then decreasing gradually to another minimum
just rearwardly of the top, said sealing portion further having a
dimension between the rim-engaging base and said sealing surface
inner periphery such that at each said minimum sealing portion
dimension between said rim-engaging base and said sealing surface
outer periphery, said sealing surface outer periphery is spaced at
least as far from the rim-engaging base as is the nearest adjacent
point on said sealing surface inner periphery, and every other
point on said outer periphery is spaced farther from the
rim-engaging base than is said sealing surface inner periphery.
15. An earcup adapted to be pressed against the head of a wearer in
surrounding relation to the wearer's ear, including
a. a rigid cup-shaped shell with a rim having an elliptically
annular plane surface facing away from said shell and defining an
elliptically annular opening into the shell interior, dimensioned
to surround the wearer's ear;
wherein the improvement comprises:
b. a softly resilient sound-attenuating pad adapted for engagement
with the head of a wearer along an area encircling the wearer's
ear, comprising:
i. an elliptically annular base having one side secured to said
shell rim and engaging said plane surface, and
ii. an elliptically annular sealing portion projecting from the
base in a direction away from said one side, and having a sealing
surface for engaging the wearer's head with elliptically annular
outer and inner peripheries surrounding said opening and spaced
apart, said surface extending substantially rectilinearly between
any given point on said outer periphery thereof to the nearest
adjacent point on said inner periphery thereof, said sealing
portion having a dimension between the rim-engaging base and said
sealing surface outer periphery which varies smoothly and
continuously around the periphery of the earcup between maxima and
minima, and said sealing surface sloping inwardly with respect to
the axis of said shell, toward said opening, with a pitch that
varies smoothly and continuously around the periphery of the earcup
between maxima and minima respectively positioned at the localities
of said maxima and minima of the sealing portion dimension between
the rim-engaging base and said sealing surface outer periphery.
16. A softly resilient sound-attenuating pad adapted to be secured
to an elliptically annular rim of a rigid earcup shell for
engagement with the head of a wearer along an area encircling the
wearer's ear, wherein said shell defines an elliptically annular
opening dimensioned to surround the wearer's ear, said pad
comprising:
a. an elliptically annular base having one side adapted to be
secured to said shell rim in engagement with an elliptically
annular plane surface thereof; and
b. an elliptically annular sealing portion projecting from the base
in a direction away from said one side, and having a sealing
surface for engaging the wearer's head with elliptically annular
outer and inner peripheries surrounding said opening and being
spaced apart substantially equidistantly from each other at all
points around the periphery of said opening, said sealing portion
having a dimension between the rim-engaging base and said sealing
surface outer periphery which varies around the periphery of the
earcup, said dimension increasing toward the front from the top to
a first maximum in the front portion of said sealing surface outer
periphery, then decreasing gradually to a minimum adjacent the
bottom, then increasing upwardly toward the back to a maximum in
the rear portion of said sealing surface outer periphery and then
decreasing gradually to another minimum adjacent the top.
17. A pad as defined in claim 16, wherein said sealing surface
extends substantially rectilinearly from any given point on said
outer periphery thereof to the nearest adjacent point on said inner
periphery thereof, and slopes inwardly with respect to the axis of
said shell, toward said opening, with a pitch that varies smoothly
and continuously around the periphery of the earcup between maxima
and minima respectively positioned at the localities of said maxima
and minima of the sealing portion dimension between the
rim-engaging base and said sealing surface outer periphery.
18. A pad as defined in claim 17, wherein said first maximum of
said sealing portion dimension is positioned about one-third of the
way to the bottom of the shell, said minimum adjacent the bottom is
positioned just forwardly of the bottom of the shell, said maximum
in the rear portion of said sealing surface outer periphery is
positioned about one-third of the way to the top of the shell, and
said minimum adjacent the top is positioned just rearwardly of the
top.
19. A softly resilient sound-attenuating pad adapted to be secured
to an elliptically annular rim of a rigid earcup shell for
engagement with the head of the wearer along an area encircling the
wearer's ear, wherein said rim defines an opening dimensioned to
surround the wearer's ear, said pad comprising:
a. an elliptically annular base having one side adapted to be
secured to said shell rim in engagement with an elliptically
annular plane surface thereof; and
b. an elliptically annular sealing portion projecting from the base
in a direction away from said one side, and having a sealing
surface for engaging the wearer's head with elliptically annular
outer and inner peripheries surrounding said opening and spaced
apart, said surface extending substantially rectilinearly between
any given point on said outer periphery thereof to the nearest
adjacent point on said inner periphery thereof, said sealing
portion having a dimension between the rim-engaging base and said
sealing surface outer periphery which varies smoothly and
continuously around the periphery of the earcup between maxima and
minima, and said sealing surface sloping inwardly with respect to
the axis of said shell, toward said opening, with a pitch that
varies smoothly and continuously around the periphery of the earcup
between maxima and minima respectively positioned at the localities
of said maxima and minima of the sealing portion dimension between
the rim-engaging base and said sealing surface outer periphery.
20. An earcup as defined in claim 1, wherein said sealing surface
is corrugated and slopes inwardly with respect to the axis of said
shell, toward said opening, with a pitch that varies smoothly and
continuously around the periphery of the earcup between maxima and
minima respectively positioned at the localities of said maxima and
minima of the sealing portion dimension between the rim-engaging
base and said sealing surface outer periphery.
21. An earcup as defined in claim 20, wherein the corrugated
sealing surface comprises plural parallel elliptically annular ribs
defining plural parallel elliptically annular grooves between them.
Description
BACKGROUND OF THE INVENTION
This invention relates to sound-attenuating earcup devices, such as
those worn by personnel working in environments where protection of
the ears from ambient noise is necessary. In many such environments
a protective helmet is also highly desirable. Consequently, it is
desirable for the earcups to be adaptable for wear either with a
safety helmet, or with some other suitable supporting structure.
Whether the supporting structure is a helmet or not, it is commonly
provided with some means for pressing the earcup against the
wearer's head. A resilient sealing pad is mounted on the rim of the
earcup, so as to engage firmly and resiliently the human head in
the area about the ear. The pressing means and the resilient pad
are intended to cooperate in closing all leakage paths by which
external sound waves might reach the wearer's ear.
Certain persons have duties to perform in environments subject to
high-intensity sounds, e.g. in the vicinity of jet engines. As the
engine power outputs become greater, the sound intensities
encountered increase, creating a demand for more effective
sound-attenuating devices.
The attempts to meet this demand have in the past taken one or both
of two directions. One direction has been to increase the force of
the pressing means to close more completely the sound leakage
paths. The other direction has been to increase the mass, or the
volume, or the flexibility of the resilient pad on the rim of the
earcup. Increasing the force of the pressing means necessarily
detracts from the comfort of the wearer, and thereby tempts him to
remove the earcups under conditions which may be dangerous to his
hearing. Increasing the mass or volume of the pad also detracts
from the wearer's comfort.
SUMMARY OF THE INVENTION
The present invention resides in a novel sealing pad mounted on the
rim of the earcup and so constructed as to close substantially all
leakage paths, thereby attenuating external sounds to a degree
greater than has heretofore been attained, with a relatively light
pressure against the wearer's head.
To this and other ends, the invention broadly contemplates an
earcup adapted to be pressed against the head of a wearer in
surrounding relation to the wearer's ear, including a rigid
cup-shaped shell with a rim having an elliptically annular plane
surface facing away from the shell and defining an elliptically
annular opening into the shell interior, dimensioned to surround
the wearer's ear, and a softly resilient sound-attenuating pad
adapted for engagement with the wearer's head along an area
encircling the wearer's ear, and having a particular contoured
configuration as hereinafter described.
More specifically, in accordance with the invention, and as a
particular feature thereof, the sound-attenuating pad comprises an
elliptically annular base having one side engaging the plane
surface of the shell rim, and an elliptically annular sealing
portion projecting from the base in a direction away from the
aforementioned one side, and having a sealing surface for engaging
the wearer's head with elliptically annular outer and inner
peripheries surrounding the opening and being spaced apart
substantially equidistantly from each other at all points around
the periphery of the opening, wherein the sealing portion has a
dimension between the rim-engaging base and the sealing surface
outer periphery which varies around the periphery of the earcup,
this dimension increasing rapidly toward the front from the top to
a first maximum in the front portion of the sealing surface outer
periphery, then decreasing gradually to a minimum adjacent the
bottom, then increasing upwardly toward the back to a maximum in
the rear portion of the sealing surface outer periphery and then
decreasing gradually to another minimum adjacent the top.
In one form of the invention, the novel resilient sealing pad
includes three distinctive features. Any of these features may be
used alone, but best results are secured by using them all.
One of the features is the transverse cross-sectional contour of
the pad. The head-engaging surface of that contour has a broad
channel shape, with divergent flanges at the sides of the channel,
the flanges terminating in smoothly curved surfaces. Those surfaces
engage the wearer's head first when the earcup is put in place, and
are spread apart by the force of that engagement. This spreading
stretches the material at the bottom of the channel, and this
tensioning of the resilient material is effective to hold the
flanges of the channel firmly against the wearer's head.
Another feature is the contour of the profile of the outer flange.
This contour follows the average humps and hollows of a human head
along a path encircling the ear. Two specifically different
contours for the outer flange are disclosed, and others are
suggested.
The head-engaging surfaces of the outer and inner flanges
respectively constitute the outer and inner peripheries of the pad
sealing surface (which also includes the channel) in this
embodiment, and the two flanges themselves comprise the sealing
portion of the pad. Thus the outer flange is contoured in
accordance with the sealing portion dimension described above.
Pressure-equalizing structures are illustrated which allow the
pressure within the earcup to follow variations in the ambient
pressure. The airflow paths in these pressure-equalizing structures
are tortuous so that sound waves moving through these pads are
attenuated, even though the flow of air is sufficiently rapid to
equalize the pressures.
In one modification, a coil spring is molded into the periphery of
a flange on the sealing pad which engages the outer side of the
earcup. The spring length is selected so that the spring is
stretched when the sealing pad is in place on the earcup. The
spring is thereby effective to hold the sealing pad in place.
In another form of the invention, the sealing surface of the pad
extends substantially rectilinearly from any given point on the
outer periphery thereof to the nearest adjacent point on the inner
periphery thereof, and slopes inwardly with respect to the axis of
the earcup shell, toward the shell opening, with a pitch that
varies smoothly and continuously around the periphery of the earcup
between maxima and minima respectively positioned at the localities
of the maxima and minima of the sealing portion dimension between
the rim-engaging base of the pad and the outer periphery of the
sealing surface.
In a modification of the last-described embodiment, the sealing
surface may be corrugated, with plural parallel elliptically
annular ribs defining plural parallel elliptically annular grooves
between them.
In each of the described embodiments, the aforementioned varying
dimension of the sealing portion, in combination with either the
flange and channel arrangement or the inwardly sloping sealing
surface, affords substantial conformity of the seal to the
hump-and-hollow contours of the average human head, and thus
enables attainment of sealing engagement between the pad and the
wearer's head in a region completely encircling the ear, without
gaps that might provide paths for transmission of sound,
notwithstanding minor variations in head contour between one wearer
and another; and at the same time, again because of the generalized
head-conforming contour of the pad, this desired sealing engagement
is achieved with advantageously light pressure on the earcup.
Further features and advantages of the invention will be apparent
from the detailed description hereinbelow set forth, together with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a vertical sectional view taken along the centerline of
an earcup embodying the invention, looking toward the front;
FIG. 2 is a vertical sectional view taken along the centerline of
the earcup of FIG. 1, but looking toward the rear;
FIG. 3 is a fragmentary cross-sectional view, illustrating the
position of the flanges when the seal is pressed against the
wearer's head;
FIG. 4 is a fragmentary view illustrating a modification of the
seal attached to the earcup;
FIG. 5 is a fragmentary view illustrating a further modification of
the seal;
FIG. 6 is a fragmentary view illustrating a modification in the
contacting surface of the seal;
FIG. 7 illustrates on an enlarged scale a pressure-equalizing
device which may be used with the earcup of the present
invention;
FIG. 8 illustrates, also on an enlarged scale, a modified form of
pressure-equalizing device;
FIG. 9 is a fragmentary elevational view of a modified form of
earcup looking from the sealing pad side;
FIG. 10 is a sectional view taken on the line 10-10 of FIG. 9;
FIG. 11 is a sectional view taken on the line 11-11 of FIG. 10;
FIG. 12 is an elevational view of a further modified form of earcup
embodying the invention, looking from the sealing pad side;
FIG. 13 is a side elevational view of the earcup of FIG. 12,
looking from the rear;
FIG. 14 is a top view of the earcup of FIG. 12;
FIG. 15 is an enlarged sectional view taken along the line 15-15 of
FIG. 12;
FIG. 16 is an enlarged sectional view taken along the line 16-16 of
FIG. 12;
FIG. 17 is an enlarged sectional view taken along the line 17-17 of
FIG. 12;
FIG. 18 is an enlarged sectional view taken along the line 18-18 of
FIG. 12;
FIG. 19 is a fragmentary elevational view of a modified form of the
earcup of FIGS. 12--18, looking from the sealing pad side; and
FIG. 20 is a sectional view taken along the line 20-20 of FIG.
19.
DETAILED DESCRIPTION
FIGS. 1--3
The sound-attenuating earcup illustrated may be supported by means
disclosed in U.S. Pat. No. 3,470,564 and is intended to be biased
lightly against the head of the wearer. For example, the biasing
means may be that disclosed in said copending application. It will
be understood, of course, that this is simply one convenient way of
biasing the earcup and is not to be taken as a limitation on the
present invention.
The earcup comprises a rigid cup-shaped shell 20 which may be of
plastic or other suitable material. The open end of the shell is
provided with an inwardly extending flange 24. This flange can be
an integral part of the shell or can be a separate element suitably
attached to the rim of the shell 20, for example, by bonding. The
principal function of the flange is to provide a broader base then
the rim of shell 20 for supporting a resilient sealing pad 30.
The shell 20 is provided with an outwardly extending pair of spaced
flanges 26, which extend peripherally around the shell 20. These
flanges 26 define a channel for receiving a shield 14 on which the
shell is supported.
The resilient sealing pad 30, which embodies the essential features
of the present invention, is elliptically annular in shape, like
the rim of the earcup 20, so as to encircle the ear of the wearer.
The pad 30 is formed of a softly resilient, preferably moldable
material, such as a sponge plastic. While many of the sponge
rubbers are suitable, it is presently preferred to use a resilient
sponge silicone. The term "sponge plastic" as used in this
specification is intended to be a generic term inclusive of sponge
rubbers and sponge silicones, as well as other sponge plastic
materials.
As seen in cross section, the pad 30 comprises a base 30a adapted
for attachment, as by bonding, to the flange 24 of the shell 20,
and divergent inner and outer head-engaging flanges 30b and 30c.
Each of the flanges 30b and 30c terminates in a smoothly curved
surface, so that it may engage the head comfortably. The flanges
30b and 30c define a broad, smoothly curved channel 30d between
them. The flanges 30b and 30c respectively extend beyond the inner
and outer peripheral walls of the base 30a to which it is attached,
as shown at 30e in FIG. 2, so that when the flanges 30b and 30c are
pushed into engagement with the wearer's head, as shown in FIG. 3,
the material at the bottom of the channel 30d is stretched, and
thereby stressed in tension. This tension of the material at 30d
pulls the flanges 30b and 30c more firmly into engagement with the
wearer's head, and greatly improves the seal against external
sounds, without increasing the wearer's discomfort. This effect may
be achieved with a total biasing force acting against the earcup of
the order of 6 to 8 ounces. This force is spread around both
flanges and around the entire periphery of the earcup, so that the
pressure felt by the wearer is extremely light.
The pad 30 is preferably provided with a flap 30f which overlies
the outer edge of the flange 24 and the outer rim of the cup 20.
This flap is particularly desirable when the flange 24 is formed
separately from the cup 20, as shown, so as to guard against
possible sound leakage paths through the connection between cup 20
and flange 24.
In order to conform to the head of a wearer, the head-engaging
surface of the pad 30 is contoured as shown in FIGS. 1 and 2. The
tip of the inner flange 30b lies in a single plane, but the outer
flange 30c follows the average humps and hollows of a human head
along a path encircling the ear. Starting from the top and
proceeding toward the front, the thickness of the flange, measured
from the rim of the earcup to the flange tip, at first increases
sharply and then decreases gradually in a downward direction along
the front of the ear, reaching a minimum at the bottom. Proceeding
upwardly along the flange behind the ear, the flange thickness
increases gradually until it reaches a maximum thickness about
two-thirds of the way to the top, and then decreases more rapidly
to another minimum at the top.
At each point around the periphery of the earcup, the thickness of
the inner flange 30b, measured from the flange 24 to the tip of
flange 30b, is less than the corresponding thickness of the outer
flange 30c at the same point. Furthermore, the thickness of flange
30b is substantially constant around the entire periphery. While
this is the presently preferred construction, it is within the
scope of the invention to make the inner flange 30b of varying
thickness, or even to make it thicker than the outer flange, at
least at some points.
In some cases, the inner flange 30b may be omitted.
The pad 30, constructed as described above, is not only more
comfortable to the wearer of the earcup than previous pad
structures, but is also more effective in attenuating external
sounds.
FIG. 4
This figure illustrates a modified pad 32, which may be used in
place of the pad 30. While the pad 30 of FIGS. 1--3 is shown as
being formed of the same material throughout, the pad 32 has an
internal space 32a filled with a core or insert 34 of a different
material, e.g. foam rubber.
FIG. 5
Here, the internal space 32a is filled with air instead of foam
rubber.
FIG. 6
This figure shows at 34 an alternative form of resilient,
head-engaging pad having two separate channels 34a, 34b, defined
between adjacent pairs of three flanges 34c, 34d and 34e.
FIG. 7
Under some conditions of use (e.g., widely varying ambient
pressures), of the earcup as described in the preceding figures, it
may be found that the earcup is too tightly sealed, so that it may
be difficult to disengage it from the head. In such circumstances,
it may be desirable to incorporate a pressure equalizer device in
the earcup.
As shown in FIG. 7, the shell 20 is provided with an aperture at a
convenient location, in which a grommet 40 of suitable material,
e.g. rubber, is inserted. The grommet 40 is itself provided with a
central aperture 40a on the periphery of which are formed helical
ridges 40b. A spool 42 having similar helical ridges 42a is
inserted in the aperture 40a. There is thus formed between the
spool 42 and the grommet 40 a tortuous passage, through which air
may slowly leak in either direction, in order to equalize pressure
differences. Nevertheless, sound waves cannot move through the
passage without substantial attenuation.
FIG. 8
This figure illustrates a modified form of pressure-equalizing
device including a grommet 50 and a spool 52, corresponding
generally to grommet 40 and spool 42 of FIG. 7. In this figure, the
helical ridges on the grommet and spool are much higher than in
FIG. 7.
In either of FIGS. 7 and 8, the spool may be assembled in the
grommet simply by threading it in, and the parts may be held
together by any suitable means, e.g. bonding.
FIGS. 9--11
These figures illustrate an earcup 20, which may be structurally
the same as the earcup 20 of FIGS. 1 to 8, on which is mounted a
modified form of sealing pad generally indicated by the reference
numeral 60. The pad 60 includes a base surface 60a adapted for
attachment, as by bonding, to the flange 24 of the shell 20 and
diverging inner and outer head-engaging flanges 60b and 60c. Except
as specifically mentioned hereinafter, the pad 60 is structurally
the same as the pad 30 of FIGS. 1 to 8.
The outer flange 60c of the pad 60 is contoured somewhat
differently than the outer flange 30c of the sealing pad 30.
Starting at the top of the outer flange and proceeding toward the
front, i.e. toward the left in FIG. 9, the thickness of the flange
60c, measured from the rim of the earcup to the flange tip,
increases gradually, reaching a maximum about two-thirds of the way
down the front side of the pad. From there, the flange thickness is
substantially constant to the bottom of the pad. Just to the rear
of the bottom, there is a pronounced valley 60d in the profile of
the pad, as seen in FIG. 10. The valley 60d is intended to
accommodate a part of the human head which protrudes just below and
behind the ear. From the valley 60d, the thickness of the flange
60c increases gradually in an upward direction, reaching a maximum
about two-thirds of the way to the top of the pad and then
decreasing gradually again until the top is reached.
The pad 60c is provided with a flap 60e, corresponding to the flap
30f of FIGS. 1 to 8. Flap 60e engages the outer surface of the cup
20 and holds the pad 60 in place on the cup. Within the flap 60e,
preferably at its innermost cup-engaging surface, there is molded a
coil spring 61. The unstressed length of coil spring 61 is smaller
than the periphery of the earcup, so that the spring 61 is
effective to hold the pad 60 firmly in position on the earcup. Note
that the spring 61 engages the earcup inside of a lip 24a formed on
the outer edge of the flange 24.
The coil spring 61 may extend continuously around the periphery of
the pad 60. Alternatively, an embedded wire may be used in place of
one or more portions of the coil spring, with the ends of such
embedded wire or wires connected by coil springs.
FIGS. 12--18
These figures illustrate a modification of the invention again
including an earcup shell 20, substantially identical in structure
to the shell 20 described above, but shown as having only a single
outwardly projecting peripheral flange 26 for attachment to
supporting structure. Thus the shell 20 has an inwardly extending
flange 24 constituting the shell rim, having an elliptically
annular planar surface and defining a generally elliptical opening.
On this shell, there is mounted a softly resilient sealing pad 63
having an elliptically annular base 63a, one side of which is
secured to the shell rim (flange 24) in engagement with the plane
surface of flange 24. The pad further includes an elliptically
annular sealing portion 63b formed integrally with base 63a and
projecting therefrom in a direction away from the shell rim, for
engagement with the head of a wearer in encircling relation to the
wearer's ear.
As shown in the sectional views (FIGS. 15--18), the pad 63 may
comprise an elliptically annular body 65 of a softly resilient
material such as a sponge plastic, e.g. of the type employed in the
pads shown in FIGS. 1--11 and described above. By way of further
illustration, a so-called "self-foaming" material (for example, a
self-foaming polyurethane composition) may be used to form the body
65, being poured into an appropriately shaped mold and caused to
expand by self-foaming action to fill the mold cavity; such
materials, and the molding procedure used to form articles from
them, are well known and accordingly need not be described in
detail. The body is encased in a flexible layer 66 of plastic
material or the like, having a flap 66a that projects outwardly
from the pad (i.e. away from the wearer's head) over the outer
surface of the cup 20 and over the lip 24a of flange 24, to aid in
holding the pad in place on the shell.
The sealing portion 63b of the pad has a sealing surface 68 which
faces away from the cup 20, in position for contact with the
wearer's head. The outer and inner peripheries of this surface,
respectively designated 70 and 71, are elliptically annular in
configuration, disposed in surrounding relation to the earcup
opening, and spaced apart substantially equidistantly from each
other at all points around the periphery of the opening, i.e. as
viewed in FIG. 12. In the form shown, the outer sidewall of the pad
sealing portion 63b diverges radially outward (with respect to the
axis of the shell 20) from the base 63a to the sealing surface
outer periphery 70, while the inner sidewall of portion 63b
projects in the direction of the shell axis from the base 63a to
the sealing surface inner periphery 71; hence the sealing surface
defined between peripheries 70 and 71 is somewhat greater in width
than the base.
In accordance with the invention, the outer thickness of the pad
sealing portion 63b (i.e. the dimension of portion 63b between the
base 63a and the sealing surface outer periphery 70) varies
smoothly and continuously around the periphery between successive
maxima and minima. FIGS. 12--18 illustrate a specific embodiment of
this dimensional variation, in an earcup for enclosing a wearer's
right ear; decreases corresponding left earcup would be a mirror
just of that shown. Starting at the top of the earcup and
proceeding initially downwardly toward the front, in FIGS. 12--18,
the sealing portion outer thickness increases rapidly to a first
maximum 70a about one-third of the way to the bottom of the shell,
then decreases gradually to a minimum 70b just forwardly of the
bottom of the shell, then increases upwardly toward the back to a
maximum 70c in the rear about a third of the way to the top of the
shell, and decreases gradually to a further minimum 70d just
rearwardly of the top of the shell.
The inner thickness of the sealing portion 63b (i.e. the dimension
of portion 63b between the base 63a and the sealing surface inner
periphery 71) is shown in FIGS. 12--18 as substantially constant at
all points around the periphery of the earcup opening and about
equal to the minimum value of the aforementioned outer thickness.
In practice, it may be desirable to provide some moderate degree of
variation in the inner thickness of the pad portion 63b, following
generally the variation in outer thickness; but in any event, the
inner thickness is such that at each minimum point (70b, 70d) of
the outer thickness the sealing surface outer periphery 70 is
spaced at least as far from the base 63a as is the nearest adjacent
point on the sealing surface inner periphery 71, and every other
point on the outer periphery 70 is spaced farther from the base 63a
than is the inner periphery 71.
Unlike the sealing surfaces of the pads of FIGS. 1--11, which are
channel-shaped in cross-sectional profile, the surface 68 of pad 63
extends substantially rectilinearly from any given point on the
outer periphery 70 to the nearest adjacent point on the inner
periphery 71. Thus the pad 63 presents a single, wide annular
head-engaging surface rather than (as in the embodiments of FIGS.
1--11) two spaced annular head-engaging surface portions
constituting the rounded crests of inner and outer flanges
separated by a channel.
Owing to the above-described relative dimensions of the outer and
inner thicknesses of the pad portion 63b (i.e. as measured at the
outer and inner peripheries of the sealing surface, respectively)
the sealing surface 68 slopes inwardly with respect to the axis of
the shell, toward the earcup opening, with a pitch that varies
smoothly and continuously around the periphery of the earcup
between maxima and minima respectively positioned at the localities
of the maxima (70a, 70c) and minima (70b, 70d) of the
aforementioned outer thickness. In other words, the surface 68
slopes relatively steeply inward from the outer periphery from
points 70a and 70c corresponding to the outer thickness maxima
(FIG. 18), and this slope flattens out as the distance between the
outer periphery 70 and base 63a decreases, until at the localities
of the outer thickness minima 70b and 70d, the surface 68 (as
viewed in cross section, FIG. 16) may be substantially parallel to
the plane of the rim flange 24. It will be understood that as
herein used, the term "pitch" refers to the angle between the
last-mentioned plane and a line, tangent to the surface 68,
projecting radially with respect to the earcup shell axis.
In use, when the earcup of FIGS. 12--18 is pressed against the
wearer's head in surrounding relation to his ear, the surface 68
engages the head (at, and at least for a substantial distance
inwardly of, the outer periphery 70 across the width of the
surface) with continuous sound-attenuating sealing contact over a
region completely encircling the ear. The described variations in
outer thickness and surface slope of the pad portion 63b follow
generally the hump-and-hollow contours of the average human head,
so that the desired complete sealing contact can be achieved with
advantageously light inward pressure. Such pressure effects
moderate outward deformation of the outer peripheral edge portion
of the pad (i.e. adjacent the outer surface periphery 70), as a
result of the described outwardly diverging configuration of the
pad outer wall, to enhance the sealing effect.
FIGS. 19--20
The sealing surface 68 of pad 63, which is shown in FIGS. 12--18 as
extending substantially rectilinearly from any given point on the
outer periphery 70 to the nearest adjacent point on the inner
periphery 71, may instead be corrugated as shown in FIGS. 19--20.
The corrugations comprise plural parallel elliptically annular ribs
74 with smoothly curved contours defining plural parallel
elliptically annular grooves 75 (also having smoothly curved
contours) between them. At any given point around the periphery of
the earcup, the crests of all the ribs 74 (across the full width of
the sealing surface) are tangent to a common line 76 extending
radially with respect to the axis of the earcup shell.
Except for the surface corrugations, the structure, configuration,
and dimensions of the pad 63 in FIGS. 19--20, including the pitch
and slope of the sealing surface, may be exactly as described above
with reference to FIGS. 12--18. It will be understood that the
terms "pitch and slope of the sealing surface," as applied to the
corrugated surface of FIGS. 19--20, refer to the pitch and slope of
the common tangent to the crests of the ribs 74.
The corrugations may conveniently be formed integrally with the
annular body 65, by molding. Use of a "self-foaming" material as
mentioned above to produce the annular body is especially effective
for forming these corrugations. The outer layer 66 is shaped to
conform closely to the corrugations of the annular body, as
illustrated in FIG. 20. In use, when the seal is pressed against
the wearer's head, the grooves 75 provide dead air spaces that
contribute to the sound-attenuating effect of the seal.
In any of the earcup devices illustrated, an earphone may be
incorporated so that the wearer may receive communications.
It is to be understood that the invention is not limited to the
features and embodiments hereinabove specifically set forth, but
may be carried out in other ways without departure from its
spirit.
* * * * *