Title:
WALL HANGING SPEAKER SYSTEM
United States Patent 3848090


Abstract:
A loudspeaker system comprising a thin square or rectangular housing to be hung on the wall of a room. The housing has an acoustically sealed chamber and an acoustically open chamber which are separated by a vertical rigid partition. The top, bottom and side walls of the sealed chamber are rigid and are connected to the partition. The front of the sealed chamber is covered with an acoustically sealed, flexible member preferably a canvas painting or a decorative panel, secured to the top, bottom and side walls of the sealed chamber. The open chamber has rigid side walls, a rigid top wall spaced below the top wall of the sealed chamber, and a rigid rear wall. The top and side walls of the open chamber are secured to the partition. The bottom of the open chamber is covered with an acoustically transparent grille cloth. A plurality of low frequency loudspeakers are mounted in and extend through the partition wall, facing into the open chamber, spaced about equidistant between the top and the bottom of the sealed chamber. A high frequency loudspeaker is mounted in the top wall of the open chamber facing upwardly and communicating with the outside of the housing. The housing is to be hung on the wall of a room so that the high frequency loudspeaker is spaced about equidistant between the ceiling and the floor of the room.



Inventors:
WALKER J
Application Number:
05/199867
Publication Date:
11/12/1974
Filing Date:
11/18/1971
Assignee:
WALKER J,US
Primary Class:
Other Classes:
381/349, 381/388
International Classes:
H04R1/28; (IPC1-7): H04R5/02
Field of Search:
179/1E,1GA,111E,115.5R 181
View Patent Images:
US Patent References:
3696885DECORATIVE LOUDSPEAKERS1972-10-10Grieg
3517769QUADRUPLE SOUND OUTPUT LOUDSPEAKER ENCLOSURE1970-06-30Broussard
3360072Sound reproducing apparatus1967-12-26Carlsson
3291251Divided panel board for hi-fi speaker systems1966-12-13Zemrowski
3240289Sound system1966-03-15Kishi
3236958Loudspeaker system1966-02-22Cohen
3233695Speaker enclosure1966-02-08Hutchins
3164221Low frequency loudspeaker system1965-01-05Rich
3115208Speaker systems and sound chambers therefor1963-12-24Smith
2757751Small extended-low-frequency-response loudspeaker enclosure1956-08-07Tavares
1771266Radio loud-speaker1930-07-22McConnel



Foreign References:
JP45008074A
DE1291790B1969-04-03
Primary Examiner:
Stewart, David L.
Attorney, Agent or Firm:
Bissell, Henry M.
Claims:
The invention claimed is

1. A loudspeaker system, comprising in combination:

2. A loudspeaker system as defined in claim 1 further comprising a second loudspeaker mounted in a wall of said open chamber and directed upwardly in communication with the outside of said open chamber.

3. A loudspeaker system as defined in claim 2 wherein said loudspeaker system is adapted to be mounted on the wall of a room about equidistant between the floor and the ceiling of the room with said flexible member facing the room and said second loudspeaker facing upwardly.

4. A loudspeaker system as defined in claim 3 wherein the sealed chamber is enclosed on five sides by rigid acoustically sealed walls, the sixth side of said sealed chamber comprising the front of the speaker system and being covered by said flexible member.

5. A loudspeaker system, comprising in combination:

6. A loudspeaker system as defined in claim 5 wherein the decorative panel comprises a canvas painting which is sealed to be non-porous.

7. A loudspeaker system as defined in claim 5 further including releasable latching means for securing the panel to the side walls of the sealed chamber in acoustic sealing relationship.

8. A loudspeaker system comprising in combination:

9. A loudspeaker system as defined in claim 8 wherein said flexible member is a canvas which is acoustically sealed with paint.

10. A system in accordance with claim 9 further including molding extending about the periphery of the canvas and spaced laterally therefrom.

11. A system in accordance with claim 8 wherein the securing means comprise releasable latching members regularly spaced about the periphery of the flexible member.

Description:
BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a loudspeaker system, and more particularly to a loudspeaker system of thin silhouette construction for use primarily in stereophonic and high fidelity systems.

2. Description of the Prior Art

Conventional stereophonic and high fidelity speakers generally use relatively deep and large enclosures which are not sufficiently versatile to be advantageously placed for the most effective stereophonic sound reproduction. Very high quality systems utilize large cabinets especially designed to transmit sound with extreme fidelity. Unfortunately, they are also very expensive and very cumbersome. Less expensive systems may give up some fidelity in sound and come in smaller cabinets but may still present a space accommodation problem. Combining a speaker enclosure with a decorative panel may permit it to be hung on the wall as a picture. Accordingly, it is desirable to provide a relatively thin silhouette speaker system for stereophonic and high fidelity systems so that the speakers may be conveniently placed on the wall of a room or the like. However, difficulty is encountered in obtaining the natural low tones when using such thin silhouette speakers. This problem becomes particularly acute at the low audio frequency range, that is, at frequencies of approximately 200 cycles per second.

Others have recently attempted to solve this problem. For example, Sechrist U.S. Pat. No. 3,160,225 discloses a porous cloth secured to a picture frame. A special bass or low tone sound chamber is provided behind the cloth. A speaker is mounted behind and facing the cloth and below the sound chamber. The sound chamber is open at its lower end in order to permit sound and air vibrations created by the speaker to enter the sound chamber. The sound is transmitted up through the chamber and discharged from a slot in the upper end of the sound chamber.

Rich U.S. Pat. No. 3,164,221 discloses a construction which employs two chambers. A speaker is flexibly mounted in a partition wall between the two chambers facing a rigid radiator diaphragm. The radiator diaphragm is flexibly mounted in an outside wall of one of the chambers. This latter chamber is hermetically sealed so that a column of air is enclosed in the chamber between the speaker and the radiator diaphragm. This column of air is employed to couple the driver diaphragm of the loudspeaker to the radiator diaphragm.

SUMMARY OF THE INVENTION

I have discovered, however, that, contrary to the teachings of the prior art, the sound reproduction quality of a less expensive system may be improved, especially at low frequencies, by providing a flexible rather than a rigid radiator diaphragm, by using an acoustically impermeable panel, and by providing other improvements which will be described hereinafter. Accordingly, the present invention comprises a loudspeaker system having an acoustically sealed chamber in front of and adjacent to an acoustically open chamber. A loudspeaker is mounted partly in one chamber and partly in the other chamber in the partition between the two. The loudspeaker faces into the open chamber. A flexible, acoustically sealed member, adapted to transmit vibrations of the loudspeaker, covers the front side of the sealed chamber. The entire enclosure is of substantial height and width but of minimal depth from front to back, thus adapting it for wall hanging without taking appreciable space in a room.

In accordance with an aspect of the invention, the front member consists principally of a decorative panel, preferably a canvas painting, which may be easily removed for replacement by a different panel--thus permitting a change of the art work displaced in association with the speaker enclosure. In a canvas or some other panel of normally open mesh, the material is acoustically sealed during preparation. For example, a canvas painting is prepared by sealing the mesh by painting. Releasable latches may be employed for securing the panel with an acoustic seal while admitting of a change of panel on the front of the enclosure.

Arrangements in accordance with the invention, used as intended, result in higher frequency sound being directed upwardly to reflect off the upper wall and ceiling of a room, thus being transformed from substantially unidirectional to generally omnidirectional in character. The portion of the sound energy in the low and mid ranges which travels downwardly and out the bottom is then directed forwardly from the lower wall to join with phase reinforcement the portion initially directed forwardly.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

A better understanding of the present invention will become apparent to those skilled in the art upon reading the following detailed description of the drawing wherein:

FIG. 1 is an elevational view of one embodiment of this invention;

FIG. 2 is a cross-sectional elevational view of the embodiment of this invention shown in FIG. 1 taken along the line 202 of FIG. 1;

FIG. 3 is a cross-sectional elevational view of the embodiment of this invention shown in FIG. 1 taken along the line 303 of FIG. 2; and

FIG. 4 is an expanded view of a portion of the section shown in FIG. 2.

DETAILED DESCRIPTION

In a preferred embodiment of the invention, the loudspeaker system has the appearance of a picture and frame when hung on the wall of a room. The rest of the speaker system is mounted behind the picture. As is shown in FIG. 1, the radiator diaphragm or flexible member 10 is surrounded by molding 12. Flexible member 10 forms the front of an acoustically sealed chamber. Loudspeakers such as 40 (FIG. 2) are mounted partly within the acoustically sealed chamber behind flexible member 10, and a short column of air or other compressible fluid is enclosed in the sealed chamber between the loudspeakers 40 and the flexible member 10.

The flexible member 10 may be decorated with a picture or the like, but in any event, the flexible member 10 is acoustically sealed. This invention will be described primarily with reference to a flexible member comprising a painted canvas. However, it will be understood that other types of flexible members and other methods of sealing the flexible member may be employed, all within the scope of this invention.

Where flexible member 10 is a canvas, the canvas is sealed by substantially filling the weave or mesh with paint or the like so that it will be parasitically driven by the driver diaphragms of the loudspeakers 40 through means of the column of air coupling the flexible member and the driver diaphragms. Thus, as used herein, the flexible member 10 is acoustically sealed when it operates as a flexible radiator diaphragm which is parasitically driven by loudspeakers. The short column of enclosed air couples the radiator diaphragm 10 to driver diaphragms of the loudspeakers 40 so that the radiator diaphragm vibrates in accordance with the vibrations of the driver diaphragms.

The area of the radiator diaphragm 10 can be the same as or different from the area of the driver diaphragms. The driver diaphragm may be the cone of a commercially available loudspeaker and the radiator diaphragm 10 may have any desired shape, including that of a planar rectangular sheet, or a dome-shaped sheet.

In the preferred embodiment of the invention, the radiator diaphragm 10 comprises a sheet of canvas or the like on which a design is painted. The entire diaphragm 10 is acoustically sealed by paint, sealer, or the like, as has been described, so that the short column of air behind the radiator diaphragm couples the driver diaphragms of the loudspeakers 40 to the radiator diaphragm 10.

As is shown in FIG. 2, which is a side sectional view of the enclosure of FIG. 1, the loudspeaker system comprises two chambers 14 and 16. The chamber 14 is acoustically sealed while the chamber 16 is acoustically open or transparent at the bottom. In accordance with what has been stated above, the chamber 14 is acoustically sealed when the flexible member 10 is adapted to be parasitically driven by the driver diaphragms of the loudspeakers 40.

The chambers 14 and 16 are separated by a common rigid partition wall 18, constructed of plywood or the like. Canvas 10 is stretched on a four-sided open frame 20. The edges of canvas 10 are folded over the sides of the frame 20 and may be secured to the inside of the frame 20 in conventional fashion. Preferably, the canvas 10 is also glued to the frame 20. All four sides of the canvas 10 are secured to the frame 20 in this manner in order to form an acoustic seal around the periphery of the canvas 10 where the front of the canvas joins the frame 20.

The canvas frame 20 is spaced from and connected to the partition wall 18 by a four-sided open spacer 22. The frame 20 is secured to the spacer 22 by means of releasable latch assemblies 24 which are accessible through the partition 18 and spacer 22 into the canvas frame 20 to lock the frame 20 in sealing juncture to the spacer 22. The spacer 22 is secured to all four sides of the frame 20 by means of these assemblies 24 suitably spaced about the entire periphery of the enclosure and, together with the canvas 10 and the frame 20, forms a rigid unit. This rigid unit may be secured to the partition wall 18 in conventional fashion by means of screws and adhesive, so as to maintain an acoustic seal therebetween. The frame 20 and spacer 22 together form the acoustically sealed top, bottom and side walls of the chamber 14. The partition wall 18 forms the back wall and the canvas panel 10 covers the front of the chamber 14.

Molding 12 may be secured around the outside of the enclosure by suitable means, such as by nails and glue. A space 23 is provided around the four sides of the canvas 10 between the sides of the canvas 10 and the molding 12 so that the canvas 10 will vibrate without interference or bias from the molding 12 bearing against the frame 20.

The molding 12, the partition wall 18, the frame 20, and the spacer 22 are all composed of a rigid material, such as plywood or the like. Since the partition wall 18, the frame 20, and the spacer 22 provide four of the walls of the chamber 14, they are also acoustically sealed. Plywood satisfies this need. At the juncture between the frame 20 and the spacer 22, a resilient seal 21 is provided in order to insure the integrity of the seal effected by the releasable latches 24 and thereby maintain the efficiency of the transfer of radiation from the loudspeakers 40 to the canvas 10 and thence into the room.

The open chamber 16 is enclosed on five sides by two rigid side walls 32, top wall 34, partition wall 18, and rear wall 36. The side walls 32 extend above and below the chamber 16 and are contiguous with the molding 12 in order to provide continuous sides for the speaker system. The top wall 34 is spaced below the top of the sealed chamber 14 and the rear wall 36 terminates short of the bottom of the sealed chamber 14.

Side walls 32, top wall 34, and rear wall 36 are constructed of rigid acoustically sealed material, such as plywood or the like. The bottom of the chamber 16 is covered with an acoustically open or transparent material 38, such as porous grille cloth, through which sound readily passes. The partition wall 18, side walls 32, top wall 34, and rear wall 36 are all secured together by nails, glue or the like. The grille cloth 38 is preferably both tacked and glued to the partition wall 18, the side walls 32, and the rear wall 36 across the open bottom of chamber 16.

In one preferred embodiment of the invention, the sealed chamber 14 is about 30 inches high by 30 inches wide by 11/8 inches deep, and the open chamber 16 is about 26 inches high by 30 inches wide by 21/2 inches deep.

In the embodiment of the invention shown in FIGS. 2 and 3, four low frequency loudspeakers 40 are mounted in the partition wall 18 about midway between the top and the bottom of the chamber 14. The loudspeakers 40 communicate with both the sealed chamber 14 and the open chamber 16 and their driver diaphragms or cones face into the open chamber 16. The loudspeakers 40 are mounted in a substantially horizontal line and are spaced about equidistant from each other and from the side walls 32. A seal (not shown) is provided between the sides of the loudspeakers 40 and partition wall 18 in order to acoustically seal the partition wall 18.

One loudspeaker 40 which has been employed in this invention is a thin rectangular speaker about 81/2 inches long by about 41/2 inches high by about 13/16 inches deep. This speaker weighs about 1 pound. Such a speaker has the advantage over the conventional cone-type speaker in that it has a shallower depth and therefore allows the chambers 14 and 16 to be of lesser depth.

One or more high frequency loudspeakers (tweeter) 42 may be mounted in the top wall 34 of the chamber 16. The loudspeaker 42 faces upwardly and the front of the loudspeaker 42 is outside the chamber 16. When the speaker system is mounted in an upright position, as is shown in FIG. 2, the speaker 42 projects high frequency sound upward against the upper wall and ceiling of the room, where it is reflected outwardly and downwardly in the room. By means of this arrangement, sound from the tweeter, which is conventionally unidirectional, is rendered omnidirectional. The speakers 40 and 42 may be connected to the output of an amplifier through a cross-over network (not shown), as is well known to those skilled in the art.

FIG. 4 shows in further detail the latching assemblies 24 present in FIG. 2. These may comprise a latch pin 25 for engagement by a receptacle 26. The pin 25 has an angled groove 27 which latches to a wire bar 28 in the receptacle 26 to pull the two tightly together and lock them in position. The receptical 26 is affixed to the frame 20 while the head 29 of the pin 25 bears against a recessed surface of the spacer 22. The canvas frame can be easily removed by releasing the assemblies 24. The slotted heads 29 of the pins 25 are readily accessible from the rear of the unit.

As may be seen in FIGS. 1 and 2, the loudspeaker system is mounted on the wall W of a room by means of fasteners 44, such as nailed hooks or the like, secured to the wall W and to the rear wall 36 of the speaker system. A wire 46 is stretched between the two fasteners 44, thus securing the speaker system to the wall W.

In the preferred embodiment of the invention, the speaker system is hung on the wall W with the high frequency loudspeaker 42 facing upwardly and positioned about halfway between the floor and the ceiling of the room. With such an arrangement, the sound from the upwardly directed high frequency loudspeaker 42 will bounce off the wall and ceiling of the room and back down into the room. The high frequency sound thus becomes dispersed throughout the room so that the sound reaches the persons listening to the music from many directions at the same time.

In operation, the low frequency sound emitted by the speakers 40 is projected into chambers 14 and 16. The sound projected into chamber 16 is directed downward and out through the acoustically transparent bottom of chamber 16. The sound projected into the chamber 14 is transmitted, in the form of vibrations, to the flexible member 10 by means of the short column of air within the chamber 14. The flexible member 10 is parasitically driven by the speakers 40 and thus serves to project sound from the speaker system with improved efficiency. The high frequency sound emitted from speaker 42 is directed upward towards the ceiling of the room and bounces off the wall and ceiling of the room at various angles, thus reducing, if not eliminating, the impression that the high frequency sound is coming from a point source.

It will be understood that this invention may be embodied in many forms other than that specifically described herein and may be employed in other ways than that specifically described herein. For example, other types of speakers and construction materials than those specified herein could be employed. It will therefore be understood that other physical configurations, components, and securing means may be employed in practicing the invention, all within the scope of the claims.