U.S. patent number 3,746,125 [Application Number 05/179,485] was granted by the patent office on 1973-07-17 for protective speaker back-can.
This patent grant is currently assigned to Lowell Manufacturing Company. Invention is credited to Josef J. Hammes.
United States Patent |
3,746,125 |
Hammes |
July 17, 1973 |
PROTECTIVE SPEAKER BACK-CAN
Abstract
An integral organic plastic back-can for protection of loud
speakers against damage and which is mildew and corrosion proof.
The back-can encloses and protects a loud speaker and may simply be
connected to a loud speaker baffle by a peripheral flange. In order
to prevent vibration and minimize resonance and sound distortion
the back-can is provided with a dish-shaped body having relatively
steep frustoconical side walls joined by a gentle radius of
curvature to a flat bottom. The flat bottom is provided with
protruding diammetrical ribs which strengthen the bottom and
prevent vibration and serve to diffuse the sound waves and minimize
resonance.
Inventors: |
Hammes; Josef J. (St. Louis,
MO) |
Assignee: |
Lowell Manufacturing Company
(St. Louis, MO)
|
Family
ID: |
22656784 |
Appl.
No.: |
05/179,485 |
Filed: |
September 10, 1971 |
Current U.S.
Class: |
181/199 |
Current CPC
Class: |
H04R
1/025 (20130101); H04R 1/021 (20130101) |
Current International
Class: |
H04R
1/02 (20060101); G10k 013/00 (); H04r 001/28 () |
Field of
Search: |
;181/31B,31R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tomsky; Stephen J.
Claims
What is claimed is:
1. In a back can for connection with a loud speaker: a molded
plastic, unitary body having steeply sloping continuous side walls
spanned by a bottom wall, the body being open at the top, the side
walls converging from the open end toward the bottom wall, the side
walls and bottom wall being connected by a curving connecting
portion integral with both bottom and side walls, the bottom wall
having integral reinforcing ribs projecting outwardly therefrom,
the sloping side walls merging by the curved connecting portion
into a rigidified bottom wall affording a back can with reduced
vibration characteristics of the kind that interfere with the
delivery of acoustical vibrations from a speaker connected with the
back can, and means for attaching a loud speaker to the open end of
the back can.
2. The back-can of claim 1 in which said ribs protrude on the
interior of said body.
3. The back-can of claim 1 in which ribs extend radially from the
center of said flat bottom and intersect with one another.
4. The back-can of claim 1 in which the body has steep
frustoconical side walls joined to the flat bottom with a gentle
radius of curvature.
5. In the back can of claim 1, the means for attaching a loud
speaker including an integral flange around the sloping side walls
of the body at their open end.
6. The back-can of claim 5 in which a speaker baffle is connected
to the peripheral flange of the back-can and extends across the
open end of the body.
7. The back-can of claim 6 in which said ribs protrude on the
interior of said body and extend radially from the center of said
flat bottom and intersect with one another.
8. The back-can of claim 6 in which the body has steep
frustoconical side walls joined to the flat bottom with a gentle
radius of curvature.
Description
SUMMARY OF THE INVENTION
By means of this invention there has been provided an integral
organic plastic back-can as an improvement over existing metallic
protective back-cans for loud speakers. Such metallic back-cans are
subject to vibration unless specially coated or covered by sound
deadening material and are subject to corrosion.
The back-can of the instant invention can be made by casting
conventional plastic materials to provide a mildew and corrosion
proof back-can without the requirement of any special coatings. A
special dish-shaped body is provided to minimize vibration and
inhibit resonance and sound distortion. This is achieved through
relatively steep frustoconical side walls joined by a gentle radius
of curvature to a flat base of the back-can body. The bottom of the
body is provided with exposed and protruding radial extending or
diammetric ribs which serve to strengthen the body against
vibration and also to minimize sound distortion and resonance by
diffusion of the sound waves from the rear of the speaker.
By means of a mounting flange the back-can can easily be connected
to a loud speaker baffle and loud speaker in a wall attached
configuration.
The above features are objects of this invention and other objects
will appear in the detailed description which follows and will be
otherwise apparent to those skilled in the art.
For purpose of illustration of this invention there is shown in the
accompanying drawings a preferred embodiment thereof. It is to be
understood that these drawings are for the purpose of example only
and that the invention is not limited thereto.
In the drawings:
FIG. 1 is a top plan view of the back-can.
FIG. 2 is a view in side elevation of the back-can.
FIG. 3 is a bottom plan view of the back-can.
FIG. 4 is an enlarged view in section taken on the line 4--4 of
FIG. 1.
FIG. 5 is a bottom plan view showing the attachment of the back-can
to a loud speaker and a baffle supported on a wall.
FIG. 6 is an enlarged view in section taken on the line 6--6 of
FIG. 5.
DESCRIPTION OF THE INVENTION
The back-can of this invention is generally identified by the
reference numeral 10. It is molded from high impact polystyrene or
other conventional organic plastic material in the form of a
dish-shaped body 12 having a peripheral mounting flange 14.
The particular configuration of the dish-shaped body is best shown
in FIGS. 2 and 6 where it will be seen that the body is comprised
of relatively steep frustoconical sidewalls 16 joined to a bottom
wall 18 by a gentle radius of curvature 20. The dish-shaped body is
connected to the peripheral mounting flange or rim 14 which is
provided with screw holes 22 for mounting to speaker baffles or
other connection.
As best shown in FIGS. 1, 3, 4, 6 the bottom wall of the back-can
is provided with inwardly protruding ribs 24. These ribs extend
radially and protrude above the surface of the bottom wall and are
criss-crossed in nature. By means of these ribs which have a
hemispherical cross section as shown in FIG. 4 strengthening of the
bottom is provided to minimize vibration and also to reduce
resonance and sound distortion by diffusion of backwardly directed
sound waves from a loud speaker cone which otherwise might bounce
off the bottom wall and distort.
The dish-shaped body of the back-can is further provided with knock
out openings 28 for ready access to electrical leads for connection
to a loud speaker.
The mounting of the back-can is shown in FIGS. 5 and 6 where a
speaker baffle is connected to the mounting flanges of the back-can
to speaker baffle 30 by screws 32. The speaker baffle is
conventionally fastened to a wall 34 or ceiling provided with an
opening receiving the back-can. A loud speaker 36 is mounted upon
the speaker baffle and extends interiorly within the opening of the
dish-shaped body of the protective back-can.
Use:
The protective speaker back-can is simply employed by connecting it
to the speaker baffle 30 shown in FIGS. 5 and 6. The speaker
extends within the dish-shaped body and is connected to the rear of
the speaker baffle. Connection of the necessary electrical leads to
the speaker 36 is accomplished by knocking out any of the necessary
knock out openings 28 for insertion of the electrical leads.
When installed the protective speaker back-can prevents moisture
damage by way of corrosion and is mildew resistant. Further,
vibration is minimized by the reinforcing and strengthening ribs
24. Distortion and resonance is minimized also by the strengthening
ribs which protrude from the inside face of the bottom of the
back-can body to diffuse and break up any bouncing and waves. The
structure of the plastic back-can obviates the necessity of a
protective or sound deadening coating or covering through the
combination of the structure of the specially shaped body with a
gentle radius of curvature of the sidewalls with the bottom and the
strengthening and sound wave diffusions ribs as afore
described.
Various modifications and changes may be made within this invention
as will be readily apparent to those skilled in the art. Such
changes and modifications are within the scope and teaching of this
invention as defined by the claims appended here to.
* * * * *