A planar waveguide speaker with controllable directivity

Abstract

This invention discloses a planar waveguide speaker with controllable directivity, comprising a speaker body. The speaker body is characterized by having a waveguide horn containing at least one sound outlet cavity. The inner surface of the sound outlet cavity includes two opposing parabolic arc surfaces and two opposing planes. By eliminating excessive transmission paths, sound pressure loss is reduced. Simultaneously, by modifying a portion of the waveguide horn's internal shape to a parabolic shape, the waveguide horn can generate cylindrical waves, improving harmful sound interference within the horn and between horns, and avoiding comb filtering in the audience's listening area.

Description

Technical Field

[0001] This invention relates to the field of speaker technology, and in particular to a planar waveguide speaker with controllable directivity. Background Technology

[0002] With social development, people's entertainment activities are increasing in number and scale. When long-distance sound reinforcement is required in large venues, line array speakers must be used to couple sound into cylindrical waves. Utilizing the principle that cylindrical waves attenuate 3dB less than spherical waves over equal distances, long-distance transmission can be achieved.

[0003] Different line array speakers use different drivers, but they are all basically composed of woofers and tweeters. Because woofers operate at lower frequencies and have longer wavelengths, they are more likely to couple with adjacent speakers to form cylindrical waves. Tweeters operate at higher frequencies and have shorter wavelengths; multiple speakers can easily generate comb filtering, making it difficult to form cylindrical waves. This necessitates that each individual speaker can generate a cylindrical tweeter wave while minimizing vertical diffusion and reducing interference between adjacent speakers.

[0004] Line array speakers typically use compression tweeters, which usually have a circular outlet and can be considered a point source. Through horn diffusion, the tweeter matches the external radiating acoustic impedance to increase sound pressure level and control the tweeter's radiation angle. Currently, most array speaker horns use the same-path method, establishing multiple transmission paths within the waveguide horn and bending some paths to make the transmission distances of each path nearly equidistant, achieving a near-cylindrical wave effect. However, to provide sufficient sound pressure, the cross-sectional size of each path cannot be too small, preventing the generated wavefront from closely resembling a cylindrical wave. The actual effect is not ideal; the tweeter's vertical radiation angle is large, the sound energy is dispersed and not concentrated, and interference between adjacent speakers cannot be effectively reduced. Comb filtering can easily occur at the speaker-to-speaker junctions, affecting the sound reinforcement effect.

[0005] Patent CN201020246532 discloses a structure that uses a parabolic structure to gather ultrasonic waves, but the patent does not disclose how to set up the speaker structure so that the speaker can emit cylindrical waves. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a planar waveguide speaker box that can generate cylindrical waves, achieve high-frequency radiation angle with small, concentrated energy and long-distance projection in the vertical direction.

[0007] The technical solution adopted in this invention is a planar waveguide speaker with controllable directivity, comprising a speaker body, characterized in that the speaker body is provided with at least one waveguide horn containing a sound outlet cavity, and the inner surface of the sound outlet cavity includes two opposing parabolic arc surfaces and two opposing planes.

[0008] The beneficial effects of this invention are: by eliminating excessive transmission paths, sound pressure loss is reduced; at the same time, by changing the shape of a part of the waveguide horn to a parabolic shape, the waveguide horn can generate cylindrical waves, and can improve harmful sound interference inside the horn and between horns, avoiding comb filtering in the audience's listening area.

[0009] As a preferred embodiment, the opening of the waveguide horn is located on one side of the speaker body, and a compression tweeter driver mounting plate is fixedly connected to the other side of the speaker body. A compression tweeter driver, connected to the waveguide horn, is mounted on the mounting plate. The output port of the compression tweeter driver is positioned at the focal point of the parabolic arc. By positioning the output port of the compression tweeter driver at the focal point of the parabolic arc, the characteristic of high-frequency sound waves propagating as rays in a large space, and the focusing principle of the parabolic focal point, are utilized. This ensures that the sound waves input from the throat of the compression tweeter unit are reflected by the upper and lower walls of the waveguide horn, outputting parallel-propagating cylindrical waves, thus minimizing the vertical radiation angle of the tweeter.

[0010] As a preferred option, the waveguide horn includes a detachably connected left horn and a right horn obtained by rotating the left horn, using a horn with rotational invariance as the connection structure, so that only one type of component needs to be manufactured during production.

[0011] As a preferred embodiment, the waveguide horn includes an upper sound-emitting cavity and a lower sound-emitting cavity arranged vertically. The left horn and the right horn are connected by a tenon and mortise joint. The left horn has a tenon structure in the upper sound-emitting cavity portion, and the right horn has a mortise structure in the upper sound-emitting cavity portion. The left horn has a mortise structure in the lower sound-emitting cavity portion, and the right horn has a tenon structure in the lower sound-emitting cavity portion; or the left horn has a mortise structure in the upper sound-emitting cavity portion, and the right horn has a tenon structure in the upper sound-emitting cavity portion, and the left horn has a tenon structure in the lower sound-emitting cavity portion, and the right horn has a mortise structure in the lower sound-emitting cavity portion. The two sound-emitting cavities and the corresponding tenon and mortise structures can achieve good rotational invariance and produce good sound output.

[0012] As a preferred option, the equation of the parabolic curve is y = ax 2 +bx+c, where a, b, and c are determined by the throat size of the compression tweeter at the focal point of the parabolic surface and the outlet size of the sound cavity. The generalized equation of the conic section is Ax. 2 +Bxy+Cy 2+Dx+Ey+F=0. The parabola needs to satisfy B²-4AC=0, and we can also assume the parabola's axis of symmetry is parallel to the y-axis. Therefore, the equation of the parabola has only 3 degrees of freedom, simplified to y=ax. 2 +bx+c. Considering that the input position of the waveguide horn needs to be located at the focal point of the parabola, and that the throat size of the matching compression tweeter and the output size of the matching speaker can be determined, the unique equation of the parabola that meets the requirements can be found. Attached Figure Description

[0013] Figure 1 This is a side perspective view of the present invention;

[0014] Figure 2 This is a schematic diagram of the overall structure of the present invention;

[0015] Figure 3 This is a schematic diagram of the longitudinal section structure of the waveguide horn of the present invention;

[0016] As shown in the figure: 1. Speaker body; 2. Waveguide horn; 3. Parabolic arc surface; 4. Sound outlet cavity; 5. Compression tweeter driver mounting plate; 6. Compression tweeter driver; 7. Left horn; 8. Right horn; 9. Throat. Detailed Implementation

[0017] The invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can implement it based on the description. The scope of protection of the invention is not limited to these specific embodiments.

[0018] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0019] This invention discloses a planar waveguide speaker with controllable directivity, comprising a speaker body 1, on which a waveguide horn 2 containing at least one sound outlet cavity 4 is disposed. The inner surface of the sound outlet cavity 4 includes two opposing parabolic arc surfaces 3 and two opposing planes. By eliminating excessive transmission paths, sound pressure loss is reduced; at the same time, by changing the shape of a portion inside the waveguide horn 2 to a parabolic shape, the waveguide horn 2 can generate cylindrical waves, and can improve harmful sound interference inside the horn and between horns, avoiding comb filtering in the audience's listening area.

[0020] The opening of the waveguide horn 2 is located on one side of the speaker body 1. A compression tweeter driver mounting plate 5 is fixedly connected to the other side of the speaker body 1. A compression tweeter driver 6, connected to the waveguide horn 2, is mounted on the compression tweeter driver mounting plate 5. The throat 9 of the compression tweeter driver 6 is positioned at the focal point of the parabolic arc surface 3. By positioning the output port of the compression tweeter driver 6 at the focal point of the parabolic arc surface, and utilizing the characteristic of high-frequency sound waves propagating in a large space as rays, and the focusing principle of the parabolic focal point, the sound waves input from the throat 9 of the compression tweeter unit are reflected by the upper and lower walls of the waveguide horn 2, outputting parallel propagating cylindrical waves, thus minimizing the vertical radiation angle of the tweeter.

[0021] The waveguide horn 2 includes a detachably connected left horn 7 and a right horn 8 obtained by rotating the left horn 7. Using a rotationally invariant horn as the connecting structure allows for the production of only one type of component. The waveguide horn 2 includes an upper and lower sound outlet cavity positioned vertically. The left horn 7 and right horn 8 are connected by a tenon and mortise joint. The left horn 7 has a tenon structure in the upper sound outlet cavity, while the right horn 8 has a mortise structure in the upper sound outlet cavity; the left horn 7 has a mortise structure in the lower sound outlet cavity, and the right horn 8 has a tenon structure in the lower sound outlet cavity; or the left horn 7 has a mortise structure in the upper sound outlet cavity, while the right horn 8 has a tenon structure in the upper sound outlet cavity; the left horn 7 has a tenon structure in the lower sound outlet cavity, and the right horn 8 has a mortise structure in the lower sound outlet cavity. The two sound outlet cavities and their corresponding tenon and mortise structures effectively achieve rotational invariance and produce good sound output. Waveguide horns require assembly of two parts, left and right. Traditional horns, due to the need for a tenon-and-mortise joint seal, have tenons and mortises on each part, with the tenons and mortises interlocking to form a seal. To address this issue, this invention employs structural optimization, using tenons and mortises at the top and bottom of the left and right parts respectively. This ensures that the two parts have completely identical shapes, requiring only two identical parts for assembly. This saves on mold costs and simplifies factory production management.

[0022] The equation of the curve of the parabolic arc 3 is y = ax 2 +bx+c, a, b, c are determined by the size of the throat 9 of the compression tweeter at the focus of the parabolic arc surface 3 and the size of the outlet of the sound cavity 4. The generalized equation of the conic section is Ax 2 +Bxy+Cy 2+Dx+Ey+F=0. The parabola needs to satisfy B²-4AC=0, and the axis of symmetry of the parabola can be set to be parallel to the y-axis. Therefore, the equation of the parabola only has 3 degrees of freedom, simplified as y=ax²+bx+c. Considering that the input position of the waveguide horn needs to be located at the focus of the parabola, and the throat size of the matching compression tweeter driver and the output size of the matching speaker can be confirmed, the unique equation of the parabola that meets the requirements can be obtained. When drawing the curve, because ordinary 3D software is difficult to draw a quadratic curve accurately, it can only calculate the coordinates of some points through the equation, and then connect these points with spline curves to obtain an approximate parabola. The accuracy of the fitting is affected by the number of sampling points and the spline curve algorithm of the software. It is impossible to draw accurately. To address this problem, this invention uses SolidWorks engineering design software, which has the function of driving curves by equations, to accurately draw the parabola shape that meets our requirements on the graph.

Claims

1. A directional controllable flat waveguide speaker comprising a speaker body (1), characterized in that, The speaker body (1) is provided with a waveguide horn (2) containing at least one sound outlet cavity (4), and the inner surface of the sound outlet cavity (4) includes two opposing parabolic arc surfaces (3) and two opposing planes. The opening of the waveguide horn (2) is located on one side of the speaker body (1). A compression tweeter fixing plate (5) is fixedly connected to the other side of the speaker body (1). A compression tweeter fixing plate (5) is provided on the compression tweeter fixing plate (5) and connected to the waveguide horn (2). The throat (9) of the compression tweeter (6) is located at the focal position of the parabolic arc surface (3). The curve equation of the parabolic curved surface (3) is y=ax 2 +bx+c, wherein a, b, and c are determined by the throat (9) size of the compression tweeter and the sound outlet size of the sound cavity (4). The waveguide horn (2) includes an upper sound cavity and a lower sound cavity arranged vertically. The waveguide horn (2) includes a detachably connected left horn (7) and a right horn (8) obtained by rotating the left horn (7). The left horn (7) and the right horn (8) are mortised and tenoned. The left horn (7) has a tenon structure in the upper sound cavity part, and the right horn (8) has a mortise structure in the upper sound cavity part. The left horn (7) has a mortise structure in the lower sound cavity part, and the right horn (8) has a tenon structure in the lower sound cavity part. Alternatively, the left horn (7) has a mortise structure in the upper sound cavity part, and the right horn (8) has a tenon structure in the upper sound cavity part. The left horn (7) has a tenon structure in the lower sound cavity part, and the right horn (8) has a mortise structure in the lower sound cavity part.

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