U.S. patent number 3,557,901 [Application Number 04/856,268] was granted by the patent office on 1971-01-26 for sound diffuser for loudspeaker and loudspeaker incorporating same.
Invention is credited to Richard Owen Young.
United States Patent |
3,557,901 |
Young |
January 26, 1971 |
SOUND DIFFUSER FOR LOUDSPEAKER AND LOUDSPEAKER INCORPORATING
SAME
Abstract
A sound diffuser unit comprising a plurality of spaced radially
arranged, spokelike members which lie in a common plane. The unit
is adapted to be supported in front of, or mounted directly on a
loudspeaker. In the preferred embodiment, each of the spokelike
members has tapered, angularly positioned, sound impinging surfaces
which converge toward the loudspeaker cone and come together along
a sound wave dividing line so that a portion of the sound emanating
from the loudspeaker will impinge on the surfaces and will be
deflected in different directions thereby to provide a greater
sound dispersion pattern than can normally be obtained from the
loudspeaker.
Inventors: |
Young; Richard Owen (Oak Park,
IL) |
Family
ID: |
25323204 |
Appl.
No.: |
04/856,268 |
Filed: |
September 9, 1969 |
Current U.S.
Class: |
181/176 |
Current CPC
Class: |
H04R
1/345 (20130101) |
Current International
Class: |
H04R
1/34 (20060101); H04R 1/32 (20060101); G10k
013/00 (); H04r 001/28 () |
Field of
Search: |
;181/31A,31.1,31 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Tomsky; Stephen J.
Claims
I claim:
1. A sound diffuser unit adapted to be supported in front of a
loudspeaker, or to be mounted directly on a loudspeaker at the base
or mouth thereof, in spaced proximity to the movable cone thereof,
said diffuser unit comprising: a plurality of radially arranged,
spokelike members to be positioned in front of the movable cone of
a loudspeaker with the inner ends thereof spaced axially from and
in substantial registry with the center of the movable cone of the
loudspeaker, the outer ends of said spokelike members extending to
the periphery of the movable cone and being spaced therefrom, said
radially arranged, spokelike members including at least one sound
wave impinging surface which faces the cone and defines a sound
wave dividing line which acts to divide and deflect sound waves
emitted by the cone in different directions thereby to increase the
dispersion pattern of the sound from the loudspeaker into an area
greater than would otherwise be obtained by the loudspeaker without
the diffuser unit.
2. The sound diffuser unit of claim 1 wherein said plurality of
radially arranged, spokelike members are joined together at their
inner ends to form a hub portion which is positioned in substantial
registry with the center of the cone of the loudspeaker.
3. The sound diffuser unit of claim 1 wherein said radially
arranged, spokelike members cover an area in front of the base or
mouth of the loudspeaker cone which is a fractional part of the
total area of the base or mouth of the cone.
4. The sound diffuser unit of claim 1 wherein said radially
arranged, spokelike members are circular or ovate in cross
section.
5. The sound diffuser unit of claim 4 wherein said radially
arranged, spokelike members are tapered, diverging outwardly from
their inner ends to the outer ends thereof.
6. The sound diffuser unit of claim 1 wherein said radially
arranged, spokelike members are triangular in cross section with
two sides thereof forming sound wave impinging surfaces which
converge to form a sound wave dividing line facing the movable cone
of the loudspeaker.
7. The sound diffuser unit of claim 6 wherein the angle between
said two sides at their point of convergence is about
90.degree..
8. The sound diffuser unit of claim 6 wherein said radially
arranged, spokelike members are tapered, diverging outwardly from
their inner ends to the outer ends thereof.
9. The sound diffuser unit of claim 1 including mounting means for
supporting the radially arranged, spokelike members in a fixed
position in front of and spaced from a loudspeaker.
10. The sound diffuser unit of claim 1 wherein the outer ends of
the radially arranged, spokelike members are provided with
extensions for securing the unit to a loudspeaker.
11. In a loudspeaker connectable to a source of audio frequency
electrical signals and including a movable diaphragm controllably
energizable in response to audio frequency electrical signals from
said source to generate sound waves both in a forward and rearward
direction, the improvement comprising: a sound diffuser unit
mounted on the loudspeaker, said unit having a plurality of
radially arranged, spokelike members positioned in front of the
movable diaphragm of the loudspeaker with the inner ends thereof
spaced axially from and in substantial registry with the center of
the movable diaphragm and the outer ends thereof extending to the
periphery of the movable diaphragm and being spaced therefrom, said
spokelike members including at least one sound wave impinging
surface which faces the movable diaphragm and defines a sound wave
dividing line which acts to divide and deflect sound waves emitted
by the diaphragm in different directions thereby to increase the
dispersion pattern of the sound from the loudspeaker into an area
greater than would otherwise be obtained by the loudspeaker in the
absence of the diffuser unit.
Description
This invention relates, generally, to apparatus for dispersing
sound emanating from a loudspeaker, and more particularly to sound
diffuser units adapted to be supported in front of loudspeakers by
separate support means, or by direct attachment to the
loudspeaker.
In the development of high fidelity loudspeakers and loudspeaker
systems, much effort has been directed to reproducing sounds which,
as faithfully as possible, simulate the sounds which were
originally produced and recorded. However, despite the greatly
improved fidelity response of present loudspeakers their inherent
sound dispersion patterns are rather narrow as compared to sound
dispersion patterns produced by musical instruments. Generally
speaking, sound dispersion patterns of loudspeakers are
substantially cone shaped diverging outwardly from the loudspeaker
with the loudest sounds being within the periphery of the base of
the cone and the diminishing sounds being outside the periphery of
the base of the cone. The cone shaped dispersion patterns become
more narrow with increasing frequency of sounds so that the high
pitch sounds appear to be within narrow beams extending in the
direction of the axis of the loudspeaker, a phenomenon called
beaming.
The beaming effect produced by loudspeakers is undesirable in that
it causes the listener to sense the direction of the sound, i.e.
from where it is coming, rather than giving the feeling that the
sound is coming from all directions. Where loudspeakers are used in
pairs to reproduce stereophonic sound much of the true stereo
illusion is destroyed. That is, before a good stereo illusion can
exist, it must seem to the listener that the reproduced sound is
not coming from any specific direction. If the ear, or the eye and
ear together, can pick out the sound source, as for example the
loudspeaker cabinet, the stereo illusion is lost or seriously
degraded. This problem is compounded by the fact that
directionality of sound, i.e. the ease with which one can detect
its source, increases with increases in audio frequency.
Prior art devices to decrease the beaming effect of loudspeakers by
diffusing the sound into larger dispersion patterns have been used.
However, such devices are either relatively complex, and,
therefore, expensive, or they substantially decrease the
loudspeaker efficiency. One such prior art device is an inverted
cone-shaped diffuser which is mounted in front of the loudspeaker,
in alignment with the cone thereof. The loudspeaker and the
inverted cone-shaped diffuser are positioned to have their axes
vertical so that the sound will be directed in a circle around the
loudspeaker thereby to fill the listening area with omnidirectional
sound. Another type of diffuser device comprises a slot formed in a
rigid wall positioned in front of the loudspeaker cone with a
substantial portion of the cone area covered. This type of
diffuser, however, decreases the efficiency of the loudspeaker
because only a small portion of the sounds produced will pass
through the slot. Yet another type of diffuser device is an
acoustic lens which delays the sound waves coming from the outer
peripheral region of the loudspeaker to form a substantially
hemispherical sound dispersion pattern. Generally this is the most
complex of the diffuser devices.
In accordance with the present invention, sound dispersing or
diffusing apparatus is provided which effectively substantially
overcomes the beaming effect produced by conventional loudspeakers.
The apparatus is relatively simple and inexpensive to manufacture,
and can be readily adapted for use with existing loudspeaker
installations. The device is usable and effective with all types of
loudspeakers, including simple and duplex cones, coaxials and
triaxials; small horns; dome radiators; planar diaphragm types; and
electrostatics.
Briefly, the apparatus of this invention comprises a loudspeaker
sound diffuser unit having a plurality of radially arranged,
spoke-like members preferably joined together at one of their ends
to form a central hub. The unit is adapted to be positioned in
front of the movable cone of a loudspeaker with the hub in registry
with the center of the cone, and is spaced therefrom a sufficient
distance to prevent the cone from making contact with the diffuser
unit when the cone is in its full forward position. The radially
arranged spoke-like members advantageously cover an area in front
of the loudspeaker cone which is only a fractional part of the
total area of the base or mouth of the cone. Thus, while the area
covered may be as high as one-half that of the base or mouth of the
cone, it preferably is less than one-half thereof. Each of the
radially arranged spoke-like members includes one, or more, sound
wave impinging surfaces. In the preferred embodiment of the
invention, the sound wave impinging surfaces comprise a pair of
elongated, tapered, or triangularly shaped, surfaces disposed at an
angle to one another which converge toward the loudspeaker cone and
come together along a sound wave dividing line which faces the
loudspeaker cone so that sound waves impinging upon each of the
surfaces will be divided and deflected in different directions to
increase the dispersion pattern of the sound waves, particularly of
the high frequency sound waves.
The radially arranged spoke-like members can take any of several
forms in cross section, as for example, ovate or round, in which
case the sound wave dividing line is the elongated portion of the
member closest the loudspeaker cone, or, they may have a triangular
cross section, in which case, as indicated above, the apex formed
by the converging sides constitutes the sound wave dividing line.
Also, the radially arranged spokelike members may be either the
same size adjacent the hub region of the diffuser unit as they are
near their outer ends, or they may be tapered, increasing in cross
section outwardly of the hub region.
The diffuser unit of this invention can be readily mounted in front
of, or directly on, a loudspeaker in any one of the several ways
disclosed hereinafter, it being understood that other methods of
mounting the diffuser unit can be effected without departing from
the broad aspects of this invention.
The above and other features and advantages of the invention will
be more fully realized and understood from the following detailed
description when taken in conjunction with the accompanying
drawings wherein like reference numerals throughout the various
views of the drawings are intended to designate similar elements or
components. In the drawings:
FIG. 1 is a front elevational view of a loudspeaker with an
embodiment of a diffuser unit of this invention mounted
thereon;
FIG. 2 is a side view of the loudspeaker and diffuser unit of FIG.
1;
FIG. 3 is a perspective view of one form of a radial member for a
diffuser unit of this invention;
FIG. 4 is a perspective view of another form of radial member for a
diffuser unit of this invention;
FIG. 5 is a front elevational view of a loudspeaker with another
embodiment of the diffuser unit of this invention mounted
thereon;
FIG. 5A is a side view of the loudspeaker and diffuser unit of FIG.
5;
FIG. 5B is a perspective view of one of the radial members of the
diffuser unit shown in FIGS. 5 and 5A;
FIG. 6 is a front elevational view of a loudspeaker with still
another embodiment of the diffuser unit mounted thereon;
FIG. 6A is a side view of the loudspeaker and diffuser unit of FIG.
6;
FIG. 6B is a perspective view of one of the radial members of the
diffuser unit shown in FIGS. 6 and 6A;
FIG. 7 is a perspective view of a loudspeaker enclosure having a
portion of the grille cloth broken away to expose several
embodiments of diffuser units of the present invention mounted in
front of the respective loudspeakers within the enclosure;
FIG. 8 is a side view, partly in section, of one arrangement for
mounting the diffuser unit and loudspeaker to a mounting board;
FIG. 9 is a side view, partly in section, of another arrangement
for mounting the diffuser unit and loudspeaker to a mounting
board;
FIG. 10 is a fragmentary side view, partly in section, showing the
radial members fastened to the rear of the grille cloth and in
front of the mouth of a loudspeaker;
FIG. 10A is a fragmentary side sectional view similar to FIG. 10
but showing the radial members mounted on the front of the grille
cloth;
FIG. 11 is a fragmentary side view, partly in section, showing the
radial members mounted to the outside of a loudspeaker mounting
board without a grille cloth interposed between the radial members
and the mounting board;
FIG. 12 is a perspective view of a loudspeaker with still another
embodiment of a diffuser unit of this invention mounted directly to
a loudspeaker; and
FIG. 13 is an enlarged fragmentary side view, partly in section,
taken along line 13-13 of FIG. 12 showing one way to mount the
diffuser unit to a loudspeaker.
Referring, now, to FIGS. 1 and 2 of the drawing, there is shown a
loudspeaker 10 having an embodiment of the sound diffuser unit,
designated generally by reference numeral 12, mounted thereon. The
loudspeaker 10 may be of conventional construction and design, and
includes a support frame 14, a magnet and coil element 16, and a
loudspeaker cone 18. The base or mouth 20 of the cone 18 is
resiliently mounted to an annular portion 14a of the support frame
14 in such a manner as to facilitate controllable forward and
rearward movement of the cone 18 under the influence of the magnet
and coil element 16.
The sound diffuser unit 12, as illustrated, comprises a plurality
of spaced apart, radially arranged, triangularly-shaped, spokelike
members 22. The members 22 may be fabricated of wood, plastic,
metal, or other rigid or semirigid material, and preferably are
symmetrically spaced with relation to one another. The members 22
advantageously are joined at their inner ends 22a to form a hub 24
which is positioned in substantial alignment with the central axis
of the loudspeaker cone 18. The outer ends 22b of the members 22,
as shown, are attached to a mounting ring 26 provided with spaced
openings 28 therethrough for receiving screws 30 for securing the
unit 12 on the annular portion 14a of the frame 14 of the
loudspeaker 10. The screws 30 desirably are of sufficient length to
enable the entire assembly to be fastened to a loudspeaker mounting
board, not shown. The combined area of the members 22, as
represented by the outer, triangularly-shaped surface 22c thereof,
advantageously is less than half of the area of the base or mouth
20 of the loudspeaker cone 18.
As shown in FIG. 3, the radial members 22 comprising the sound
diffuser unit 12 can take the form of an elongated tapered
tetrahedron having a triangular cross section. The tetrahedron has
a pair of sound impinging surfaces 22d-22d which converge in the
direction of the loudspeaker cone 18 and come together along a
sound wave dividing line 22e so that sound waves impinging upon
each of the radial members 22 will be divided and directed in
different directions substantially to increase the sound wave
dispersion pattern of the loudspeaker 10. In the preferred
embodiment of this form of the radial members, the angle A defined
by the surfaces 22d-22d is approximately 90.degree..
Referring, now, to FIG. 4 there is illustrated another form of
radial member. The radial member, designated by reference numeral
32, is shaped like an elongated one having a circular or ovate
cross section. The sound wave dividing line of the member 32 is
that portion 34 thereof closest to the loudspeaker cone 18.
FIGS. 5, 5A and 5B illustrate an alternate form of the sound
diffuser unit of this invention. As shown, the unit 40, as in the
case of the unit 12, is mounted in front of a loudspeaker 10. Here,
the radial members 42 are arranged substantially as shown in FIGS.
1 and 2. However, each of the radial members 42 are of uniform
triangular cross section from the inner end 42a to the outer end
42b thereof, except for a small tapered portion 42c joined to the
inner end 42a which forms part of a central hub 44. The tapered
portions 42c can be fastened together in any convenient manner, as
by gluing, or the like, it being understood that any of the forms
of sound diffuser unit shown herein may be molded as a unitary
structure. The radial members 42, as in the case of the members 22,
have a pair of sound wave impinging surfaces 42d-42d which converge
toward the loudspeaker cone 18 and come together along a sound wave
dividing line 42e.
FIGS. 6, 6A and 6B illustrate a diffuser unit 50 wherein the radial
members 52 are essentially circular in cross section. The members
52 are of uniform diameter, and are joined at their inner end to a
tapered portion 52c. The portions 52c advantageously are secured to
one another, as before, to form a hub 54. The sound wave dividing
line of each of the members 52 is that portion 52e thereof closest
to the loudspeaker cone 18.
Referring, now, to FIGS. 7 and 8, there is shown a bookshelf type
loudspeaker enclosure 60 with a major portion of a grille cloth 62
broken away to show a plurality of loudspeakers each having a sound
diffuser unit, such as unit 12, mounted thereon. A pair of smaller
loudspeakers 64 and 66, and a larger loudspeaker 68, are shown in
the enclosure 60 to illustrate a common combination of large and
small loudspeakers. The loudspeakers, with the diffuser units
mounted thereon, are secured to a mounting board 70 by means of
screws 72-72. As best shown in FIG. 8, the mounting board 70 has an
aperture 74 which is of a diameter substantially equal to the
diameter of the base or mouth 20 of the loudspeaker cone so that
the annular portion 14a and the support ring 26 extend beyond the
aperture 74 and can be secured to the rear of the mounting board 70
by the screws 72.
In FIG. 9, a loudspeaker 80 is fastened directly to a mounting
board 82 by, for example, screws 84-84. However, the diffuser unit
86 has an outside diameter which is the same as, or slightly less
than that of the aperture 88 in the board 82, and snugly fits
therein where it can be held in place by glue, or the like. In this
embodiment of the invention, it is preferred that the mounting
board 82 have the same thickness as the support ring 90 of the unit
86 so that the unit 86 will not interfere with either the forward
movement of the loudspeaker cone 18 of the loudspeaker 80, or the
grille cloth 92.
FIG. 10 illustrates an arrangement for mounting a diffuser unit 100
to the rear surface of a grille cloth 102. Here, the annular
support ring is eliminated and only the radial members 104 are
used. As shown, the members 104 are secured, as by glue or staples,
to the rear of the grille cloth 102 so that they lie within
aperture 106 in the mounting board 108 and are in registry with the
loudspeaker cone 18. Preferably, the outer ends 104b of the radial
members 104 are tapered, or slanted outwardly so that they will
conform to the diverging inner wall of the loudspeaker cone 18.
This is especially desirable in those instances where the
loudspeaker cone has a relatively large forward movement in that it
prevents the outer edges of the cone from making contact with the
radial members. After the radial members 104 are fastened to the
grille cloth 102, the loudspeaker 110 is mounted in the usual
manner over the aperture 106.
FIG. 10A shows an alternate form of the mounting arrangement of
FIG. 10. Here, the radial members 104 are fastened to the front
surface of the grille cloth 102 to increase the dispersion pattern
of the sound wave from a loudspeaker 110, and to serve as an
ornamental design on the front of the enclosure involved. When
mounting the radial members 104, as shown in FIG. 10A, the sound
wave dividing lines 104e of the members 104 are parallel to the
plane of the base or mouth loudspeaker cone, similar to that of the
sound wave dividing lines 42e of the diffuser unit 40 shown in FIG.
5A.
In FIG. 11, the radial members 120 are shown to be of a length
greater than the radius of the aperture 122 in a mounting board
124, whereby the outer ends 120b thereof extend beyond the
periphery of the aperture 122 and are fastened to the mounting
board 124 as by gluing. Here, a grille cloth may or may not be used
as desired. Also, in the embodiments shown in FIGS. 10, 10A and 11,
the inner ends of the radial members may or may not be joined, as
desired.
Referring, now, to FIGS. 12 and 13 a loudspeaker 130 has a diffuser
unit 132 mounted thereto to form an integral structure. In this
instance, the diffuser unit 132 has eight radial members 134 which
are fastened together at their inner ends 134a, it being understood
that less than, or more than, that number of radial members may be
used. The outer ends 134b of the radial members 134 are fastened to
the annular mounting flange 136 of the loudspeaker 130 by any
suitable means. FIG. 13 illustrates one preferred form of mounting
the ends 134b on the flange. As shown, a bracket 140 extends
outwardly and rearwardly of each radial member 134. The outer end
140a of the bracket 140 is bent to extend substantially parallel to
the plane of the base or mouth of the loudspeaker 130 and is
embedded in an annular gasket 142. The manner in which the end 140a
of the bracket 140 is secured at the mounting flange may, of
course, vary. Thus, for example, the end 140a may be placed behind
the gasket 142, in which case an annular inner portion of the
gasket may be cut away to accommodate a bracket which extends
rearwardly to a lesser degree so as to maintain a suitable distance
between the radial members 134 and the loudspeaker cone 18 when the
cone is in its full forward position.
While for purposes of illustration preferred forms of the present
invention have been described, it should be understood that
variations and modifications may be effected therein without
departing from the spirit and scope of the novel concepts disclosed
and claimed herein.
* * * * *