WO2000056131A1

WO2000056131A1 - Loudspeaker with differentiated energy distribution in vertical and horizontal planes

Info

Publication number: WO2000056131A1
Application number: PCT/US2000/006000
Authority: WO
Inventors: Richard W. Lehman
Original assignee: Clair Brothers Audio Enterprises, Inc.
Priority date: 1999-03-12
Filing date: 2000-03-09
Publication date: 2000-09-21
Also published as: AU3871000A

Abstract

A loudspeaker horn, loudspeaker and a loudspeaker system wherein at least one loudspeaker includes a horn composed of a wave guide (15), a plurality of throats (14a-14d) acoustically coupled to a single wave guide (15) at their mouths and to respective drivers of a plurality of drivers (13a-13d) at their inlets. The axis of the throats form an arc in the plane of the long axis of the wave guide (15) to optimize energy distribution in this plane.

Description

LOUDSPEAKER WITH DIFFERENTIATED ENERGY DISTRIBUTION IN VERTICAL AND HORIZONTAL PLANES

BACKGROUND OF THE INVENTION

(1) Field of the Invention The present invention relates to the field of high power loudspeakers and in particular, to a loudspeaker system, a loudspeaker and a loudspeaker horn providing a predefined coverage pattern fed by an optimally shaped wave front created by an array of multiple drivers.

(2) Description of Related Art In the field of generating and distributing acoustic energy and in particular where the acoustic energy is to be received and recognized by a large number of listeners who are distributed over a given area, many loudspeaker arrangements use multiple horns. Horns generally have an expanding cross-sectional area moving away from the acoustic source such that, in general terms, the horn is used to direct the acoustical energy along the axis of the horn.

Horns have very specific directional acoustical energy distribution characteristics. These characteristics are utilized in applications where the listeners are within a predetermined area relative to the arrangement of the horns. Such applications include but are not limited to open and closed sports arenas, for example.

One conventional directional loudspeaker is disclosed in U.S. Patent No. 4,344,504 issued to Bruce Howze on August 17, 1998. In this patent, a loudspeaker is disclosed to allegedly have uniform horizontal sound dispersion characteristics in a design angle while having minimal vertical sound dispersion. It utilizes multiple sound energy sources which form an elongated line source of sound energy, and a waveguide having an elongated input portion coextensive with the elongated line source. The planar side walls of the waveguide minimize sound dispersion in a direction parallel to the line source while expanding the sound dispersion in a direction perpendicular to the axis of the line source, thereby differentiating the sound dispersion between vertical and horizontal planes.

In the Howze directional loudspeaker, the line source is formed in a single plane and the mouths of the horns are also in a single plane.

The Howze directional loudspeaker suffers from a number of drawbacks. For instance, vertical sound dispersion is not constant with frequency over the intended bandwidth. Additionally, vertical sound dispersion is preferred in some environments, thus making the Howze directional loudspeaker inappropriate.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a tightly controlled energy distribution pattern in a horizontal plane over a broad frequency range. It is another object of the present invention to provide a tightly controlled energy distribution pattern in a vertical plane over a broad frequency range.

It is still another object of the present invention to significantly increase the amount of acoustic energy in a defined area, as compared to a commonly used single driver horn. It is still yet another object of the present invention to provide a coherent acoustical wave front that mimics a single idealized point source with a defined energy distribution pattern.

It is still yet a further object of the present invention to eliminate or ameliorate to insignificance the interference patterns caused by multiple time arrivals in horn arrangements which are specifically designed to increase the energy density over a defined area by overlap of multiple single driver horn patterns on the defined area. It is still yet another object of the present invention to optimize the amount of acoustical energy delivered by an array of multiple driver horns to a defined area by adjustment of the vertical and/or horizontal coverage angles of the individual multiple driver horns in the array. These and other objects and advantages are achieved by providing a horn including a plurality of electroacoustical drivers for generating sound waves over a range of frequencies and each having a sound outlet port; a plurality of throat sections each having an axis and each extending from an inlet to a mouth, wherein inlets of respective throat sections of said plurality of throat sections are acoustically coupled to said outlet ports of respective drivers of said plurality of drivers; and a single waveguide, wherein said mouths of respective throats of said plurality of throat sections are acoustically coupled to said single waveguide, whereby the axes of said plurality of throat sections form an arcuate array in a first plane. The present invention may also be embodied in a loudspeaker including a housing and at least one of the above described inventive horns.

The present invention may further be embodied in a loudspeaker system including a plurality of loudspeakers, at least one of the plurality of loudspeakers having a housing and at least one inventive horn. Further, the loudspeaker system may include a plurality of loudspeakers in the form of an array wherein at least one loudspeaker is at an angle (greater than 0°, and less than 180° ) relative to an adjacent loudspeaker.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of exemplary embodiments to which it is not limited as illustrated in the accompanying drawings, in which:

Figure 1 is a perspective drawing of one embodiment of a full range loudspeaker system incorporating the present invention; Figure 2 is a perspective drawing of the center horn with four center throats and the waveguide which controls the horizontal energy distribution pattern of the loudspeaker shown in Figure 1 ;

Figure 3 is a side view of the center horn with four center throats shown in Figure 2 illustrating the vertical angle of coverage of the present invention;

Figure 4A is a top view of a small array showing the horizontal coverage of the loudspeaker within an array;

Figure 4B is a side view of three of the center horns arrayed in a vertical plane; Figures 5A and 5B are graphic representations of the vertical and horizontal energy distributions, respectively, of the array shown in Figures 4A and 4B;

Figure 6 is an array of loudspeakers incorporating the present invention; and Figure 7 is an oblique view of the array of loudspeakers shown in Figure 6.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 illustrates a loudspeaker of a high fidelity speaker system. It includes a shell or housing 10. In the housing 10 are a woofer, mid-range speakers, and tweeters. The woofer mount 11 with an aperture for the woofer is shown in Figure 1. The woofer and four conventional mid-range speakers are shown in each of the twelve loudspeaker cabinets of Figure 7. As is conventional, the woofer produces sound in the range of 200Hz or less.

Adjacent to the mount 11 for the woofer is a center horn 12 in accordance with the present invention which provides sound in a much higher and broader range (e.g. , 1.5 - 20 kHz range), and can be considered a mid-range to tweeter speaker. The center horn 12 consists of a plurality of center array drivers (e.g. , four drivers) 13a-13d which are acoustically coupled to respective center throats of an array of center throats 14a-14d. These center throats are offset relative to an immediately neighboring throat by a given angle in a direction perpendicular to a plane of symmetry between the throats as shown. Hence, a sum of the individual widths of the several drivers in a first direction can be greater than the total height of the drivers in the array in the illustrated embodiment. However, they can be placed in a single plane.

The output ports of the center array drivers 13a- 13d are acoustically coupled to the inlets of the center throats 14a-14d. The mouths of the center throats 14a-14d are acoustically coupled to a single center array waveguide 15. The array drivers 13a-13d, the throats 14a-14d, and the single waveguide 15 thus constitute the center horn 12.

As illustrated in Figures 2 and 3, the axis of the throats 14a-14d of the center horn 12 form an arcuate array in the vertical plane. It should be noted that, while the terms vertical and horizontal are used as points of reference, these terms can be interchanged without affecting the invention. In fact, any orientation of the various elements with respect to a reference plane is contemplated.

The center array waveguide 15 is shaped as an arc in the vertical plane. Similarly, the small horn 16 includes a plurality (e.g., 12) of drivers 17a- 17m acoustically coupled to small array throats 18a-18m. As with the center array waveguide 15, the small array throats 18a- 18m are acoustically coupled to a single small array waveguide 19. The operation and construction of the small horn 16 is much the same as the center horn 12 but for the inclusion of additional drivers 17a- 17m which provide extra power in the high frequency ranges, as well as smaller throats 18a- 18m and waveguide 19 dimensions to generate sounds in the range of 6 kHz and up. The small horn 16 may be considered a tweeter. It should be noted that on either side of the small horn 16 can be placed mid-range speakers (shown in Figure 7), such as four evenly spaced mid-range speakers, two on either side of the small horn 16 in stacked relationship. The mounts for the two sets of two mid-range speakers may form a chevron shape with the center of the chevron on either side of the small horn 16 and extending to the outer surface of the housing 10. The center horn 12 can have an overlapping range to the tweeter 16, and hence the tweeter 16 can be omitted under some circumstances.

With respect to center horn waveguide 15 and the similar construction of the small horn waveguide 19, these waveguides' outer surfaces on the sides 15a, 15b (and 19a, 19b) have two angles relative to the central plane of the throats 14a- 14d (and 18a- 18m). The center plane is referred to as the "0" line in Figures 4A and 4B, for instance.

The waveguides 15 and 19 of the center and small horns 12 and 16 can include complete top and bottom sides 19c (only one shown as the top side of the housing 10 is omitted for illustration) as shown with respect to the waveguide 19 of the small array 16 or have vestigial top and bottom side walls 15c, e.g. , with a chevron cut out at an angle matching the more posterior side surface of the waveguides 15a, 15b, 19a, 19b, for optimum sound quality. Alternatively, the waveguide top and bottom side walls may be omitted.

Figure 4A is a top view of the center horn 12 showing the horizontal coverage. The angle is the angle of propagation relative to a center, vertical plane of the array. The angle α may be slightly different than the innermost surface of the waveguide 12 (or 16). An outer edge of sound distributed by the horn is approximately in a horizontal plane and approximates the angle of the inner surface (e.g. , 15a') of side surface (e.g. , 15). This line of intersection 40 is to the rear of the mouths of the throats 14a- 14d.

Figure 4B illustrates use of three horns 12, one stacked upon the other with each horn maintaining the arcuate relationship of the individual throats 14a- 14d of each horn 12 in the vertical plane in a proper array.

Figure 5A is a polar plot of the vertical energy distribution, whereas Figure 5B is a polar plot of the horizontal energy distribution of the arrays shown in Figures 4A and 4B. Marks for and 360 - in the plot of Figures 4A correspond to similar marks in Figure 5A and likewise marks β and 360 - β of Figure 4B correspond to similar marks in Figure 5B. As illustrated, it can be seen that the energy distribution is very efficient.

Figures 6 and 7 illustrate arrays of loudspeakers 60, each loudspeaker or at least one of the loudspeakers being in accordance with the present invention. As illustrated in Figure 6, four such loudspeakers 61 are at nearly 90° in the horizontal planes and at nearly 0° in the vertical plane to project the sound a long distance (i.e., a long throw). Figure 6 also shows four speakers 62 in an arcuate array each being offset from its neighbor by 5 ° . This arrangement projects sound a medium distance or a medium throw. The last set of four speakers 63 are offset from one another by 10° and projects sound a relatively short distance or short throw. Figure 7 is an oblique view of the array shown in Figure 6 wherein all of the speakers are in accordance with the present invention.

From the forgoing, it can be seen that the present invention to provide a tightly controlled energy distribution pattern in a horizontal plane over a broad frequency range by means of a plurality of drivers respectively coupled to respective horizontally offset throat sections, which are in turn coupled to a single waveguide.

The present invention also provides a tightly controlled energy distribution pattern in a vertical plane over a broad frequency range by means of aligning axes of the plurality of throat sections to form an arcuate array in the vertical plane.

The present invention further significantly increases the amount of acoustic energy in a defined area, as compared to a commonly used single driver horn by this inventive arrangement.

By this arrangement, the present invention additionally provides a coherent acoustical wave front that mimics a single idealized point source with a defined energy distribution pattern.

By this arrangement, the present invention eliminates or ameliorates to insignificance the interference patterns caused by multiple time arrivals in horn arrangements which are specifically designed to increase the energy density over a defined area by overlap of multiple single driver horn patterns on the defined area.

The present invention optimizes the amount of acoustical energy delivered by an array of multiple driver horns to a defined area by adjustment of the vertical and/or horizontal coverage angles of the individual multiple driver horns in the array.

The present invention has been described by way of exemplary embodiments to which it is not limited. Modifications and variations will occur to those skilled in the art without departing from the scope and spirit of the invention as reflected in the appended claims.

Claims

Claims:

1. A horn comprising: a plurality of electroacoustical drivers for generating sound waves over a range of frequencies, each having a sound outlet port; a plurality of throat sections each having an axis and each extending from an inlet to a mouth, wherein inlets of respective throat sections of said plurality of throat sections are acoustically coupled to said outlet ports of respective drivers of said plurality of drivers; and a single waveguide, wherein said mouths of respective throats of said plurality of throat sections are acoustically coupled to said single waveguide, and wherein said mouths of said plurality of throat sections are disposed on an arcuate line in a first plane.

2. The horn according to claim 1, wherein said axes of said plurality of throat sections form an arcuate array with a point of convergence on the driver side of the horn.

3. The horn according to claim 1 , wherein alternating throat sections are in a plane which is offset by a given angle relative to a plane in which adjacent throat sections appear, in a direction perpendicular to said first plane.

4. The horn according to claim 3, wherein said plurality of throat sections are in said first plane.

5. The horn according to claim 3, wherein a sum of individual widths of said plurality of drivers in a first direction is greater than the total height of said plurality of drivers in the array.

6. The horn according to claim 5, wherein an imaginary zig-zag line interconnects center points of said drivers of said plurality of drivers.

7. The horn according to claim 1, wherein an angle in said first plane between axes of individual throat sections of said arcuate array is greater than 0° .

8. The horn according to claim 1, wherein said waveguide includes a slot each side of which is formed by an anterior surfaces and a posterior surfaces, the anterior surfaces forming a smaller angle to said first plane than said posterior surfaces.

9. The loudspeaker according to claim 1, wherein said waveguide includes top and bottom sides.

10. The loudspeaker according to claim 1, wherein said waveguide includes vestigial top and bottom sides.

11. The horn according to claim 1, wherein an outer edge of sound distributed by said horn is approximately in a second plane perpendicular to said first plane and intersects a surface of said waveguide and an axial line of respective throat sections within said respective throat sections.

12. A horn array comprising: a plurality of horns in an array, each horn including: a plurality of electroacoustical drivers for generating sound waves over a range of frequencies, each having a sound outlet port; a plurality of throat sections each having an axis and each extending from an inlet to a mouth, wherein inlets of respective throat sections of said plurality of throat sections are acoustically coupled to said outlet ports of respective drivers of said plurality of drivers; and a single waveguide, wherein said mouths of respective throats of said plurality of throat sections are acoustically coupled to said single waveguide, and wherein said mouths of said plurality of throat sections are disposed on an arcuate line in a first plane.

13. The horn array according to claim 12, wherein at least one horn of said array is at an angle relative to an adjacent horn.

14. The horn array according to claim 12, wherein said axes of said plurality of throat sections form an arcuate array with a point of convergence on the driver side of the horn.

15. The horn array according to claim 12, wherein each throat section is offset relative to an adjacent throat section by a given angle in a direction perpendicular to said first plane.

16. A loudspeaker comprising: a housing; and at least one horn including a plurality of electroacoustical drivers for generating sound waves over a range of frequencies, each having a sound outlet port; a plurality of throat sections each having an axis and each extending from an inlet to a mouth, wherein inlets of respective throat sections of said plurality of throat sections are acoustically coupled to said outlet ports of respective drivers of said plurality of drivers; and a single waveguide, wherein said mouths of respective throats of said plurality of throat sections are acoustically coupled to said single waveguide, and wherein said mouths of said plurality of throat sections are disposed on an arcuate line in a first plane.

17. The loudspeaker according to claim 16, further comprising a conventional woofer.

18. A loudspeaker system comprising: a plurality of loudspeakers, at least one of said plurality of loudspeakers including: a housing; and at least one horn including a plurality of electroacoustical drivers for generating sound waves over a range of frequencies, each having a sound outlet port; a plurality of throat sections each having an axis and each extending from an inlet to a mouth, wherein inlets of respective throat sections of said plurality of throat sections are acoustically coupled to said outlet ports of respective drivers of said plurality of drivers; and a single waveguide, wherein said mouths of respective throats of said plurality of throat sections are acoustically coupled to said single waveguide, and wherein said mouths of said plurality of throat sections are disposed on an arcuate line in a first plane.

19. The loudspeaker according to claim 18, wherein said plurality of loudspeakers form an array wherein at least one loudspeaker is at an angle relative to an adjacent loudspeaker.

20. The loudspeaker according to claim 19, wherein said angle is greater than 0°.

21. The loudspeaker according to claim 19, wherein said angle is 180° or less.

22. The loudspeaker according to claim 19, wherein said angle is about

5° .

23. The loudspeaker according to claim 18, wherein said at least one loudspeaker includes a conventional woofer.