Directional loudspeaker box with directional acoustic transmission holes

A directional loudspeaker box with directional acoustic transmission holes includes a hollow housing and a loudspeaker. The hollow housing is provided with a front opening at the front end and has a peripheral portion adjacent to the front opening and formed with a plurality of directional acoustic transmission holes. The loudspeaker is fixed in the hollow housing and generates sound that can propagate out of the hollow housing through the front opening and the directional acoustic transmission holes. The angle at which each directional acoustic transmission hole is formed with respect to the central axis of the loudspeaker is a function of the axial distance between the directional acoustic transmission hole and the loudspeaker, wherein the smaller the axial distance, the larger the angle, and the larger the axial distance, the smaller the angle. Thus, the directional loudspeaker box effectively deals with near- and far-field sound effects.

FIELD OF THE INVENTION

The present invention relates to loudspeaker boxes and more particularly to one provided with a plurality of directional acoustic transmission holes whose angles with respect to the central axis of the loudspeaker vary with their respective axial distances to the loudspeaker so that sound can propagate out of the loudspeaker box in different directions to cater for listeners in both the near and far fields.

BACKGROUND OF THE INVENTION

The great leaps forward in industrial technology and continual development of multimedia products have enabled tremendous satisfaction of our senses of sight and hearing. In particular, many music companies nowadays have launched online music services that allow users to listen to music and songs directly through the Internet without having to buy CDs or vinyl records. As listening to music with earphones incurs compression, and hence discomfort, of the ears and keeps the listener from lying on one side of the body or making large movements at will, a desirable alternative is to play music through a stereo system, whose loudspeaker quality is also far superior to that of earphones and therefore ensures better enjoyment of music.

Generally, a stereo system designed to make the most of acoustic resonance to create a satisfactory sound field has a loudspeaker mounted in a loudspeaker box. The cavity in the box serves as a resonance chamber, which amplifies the sound output from the loudspeaker. Referring toFIG. 1, a conventional loudspeaker box L includes a hollow housing L1, a loudspeaker L2, and a cover L3. The hollow housing L1is provided with an opening L11at the front side and a receiving space L12in its interior. The receiving space L12is in communication with the opening L11in order to receive a sound source control circuit L13. The loudspeaker L2is mounted to the cover L3and is electrically connected to the sound source control circuit L13in order for the membrane of the loudspeaker L2to vibrate according to audio signals transmitted from the sound source control circuit L13and thereby produce the corresponding sound effects. The cover L3is mounted to the hollow housing L1to cover the opening L11. When the membrane of the loudspeaker L2applies a rearward pushing force to the air in the hollow housing L1by instantaneous vibrations, the hollow housing L1resonates at a low frequency.

Since stereo systems can be used for different purposes and in different places (e.g., in the living room of a residence, in an outdoor plaza, at a concert venue, on an athletic field, etc.), people's requirements of such systems are not exactly the same, and in light of this, structural improvements have been made to loudspeaker boxes to meet user needs. The applicant of the present invention has found that the existing loudspeaker boxes can be roughly divided into two major categories: household loudspeaker boxes, whose range of sound projection is relatively small, and those for use with public address (PA) loudspeakers, which feature relatively far sound projection; and that a loudspeaker box that takes into account both near-field and far-field sound effects has yet to be developed. For example, a PA loudspeaker will produce an undesirable sound effect to those who are close to it (i.e., in the near field). After all, the placement of a loudspeaker box requires various spatial acoustic conditions to be considered. The issue to be addressed by the present invention, therefore, is to design a novel loudspeaker box structure configured for both the near and far fields in order to provide users with a better listening experience.

BRIEF SUMMARY OF THE INVENTION

In view of the fact that the conventional loudspeaker boxes may result in a less-than-satisfactory listening experience due to failure to accommodate both the near and far fields, the inventor of the present invention incorporated years of practical experience in the industry into extensive research and repeated trials and finally succeeded in developing a directional loudspeaker box with directional acoustic transmission holes as disclosed herein. It is hoped that the invention can furnish a more satisfactory listening experience and be favored by users.

It is an objective of the present invention to provide a directional loudspeaker box having directional acoustic transmission holes. The loudspeaker box includes a hollow housing and a loudspeaker. The hollow housing is barrel-shaped, is provided therein with a receiving space, and has a front end provided with a front opening in communication with the receiving space. A peripheral portion of the hollow housing that is adjacent to the front opening is formed with a plurality of directional acoustic transmission holes. Each directional acoustic transmission hole penetrates the hollow housing, is open on both the inner and outer walls of the hollow housing, and is in communication with the receiving space. The loudspeaker is fixed in the hollow housing and divides the receiving space into a front acoustic cavity and a rear acoustic cavity. The front opening and the directional acoustic transmission holes correspond to the front acoustic cavity. The central axis of the front opening coincides with that of the loudspeaker. The central axis of each directional acoustic transmission hole forms an included angle with the central axis of the loudspeaker, wherein the included angle is a function of the axial distance between the directional acoustic transmission hole and the loudspeaker along the axial direction of the hollow housing. More specifically, the smaller the axial distance, the larger the included angle, and the larger the axial distance, the smaller the included angle. Thus, the sound generated by the loudspeaker can travel through the front acoustic cavity and then propagate out of the front acoustic cavity in different directions via the front opening and the directional acoustic transmission holes. The barrel-shaped configuration of the directional loudspeaker box helps project the sound generated by the loudspeaker to a great distance while the directional acoustic transmission holes enhance the near-field sound effect.

Another objective of the present invention is to provide the foregoing directional loudspeaker box, wherein the hollow housing is provided therein with a spoiler portion. The spoiler portion is located between the front opening and the membrane of the loudspeaker along the same central axis thereof to form a compression channel in the front acoustic cavity. Thus, the sound generated by the loudspeaker can propagate out of the front acoustic cavity through the front opening under compression of the compression channel. The spoiler portion and the compression channel are designed to generate a turbulent flow in, reflect, compress, concentrate, and then release the air (or sound) in the hollow housing, thereby increasing the distance of acoustic transmission effectively.

Still another objective of the present invention is to provide the foregoing directional loudspeaker box, wherein the inner wall of the hollow housing is protrudingly provided with a plurality of spoiler plates respectively adjacent to the directional acoustic transmission holes. Each spoiler plate surrounds the inner periphery of the corresponding directional acoustic transmission hole such that a directional spoiler channel is formed between each spoiler plate and the corresponding directional acoustic transmission hole. Each directional spoiler channel is in communication with the front acoustic cavity at one end and with the corresponding directional acoustic transmission hole at the opposite end. The sound generated by the loudspeaker can travel through the front acoustic cavity, be reflected by the directional spoiler channels, and then propagate out of the front acoustic cavity in different projection directions via the directional acoustic transmission holes, wherein the projection direction varies with the axial distance between each directional acoustic transmission hole and the loudspeaker. More specifically, the smaller the axial distance, the larger the projection angle, and the larger the axial distance, the smaller the projection angle. Due to compression by the spoiler plates, the sound generated by the loudspeaker can propagate out of the front acoustic cavity in different directions, and the distance of acoustic transmission through each directional acoustic transmission hole is increased.

Yet another objective of the present invention is to provide the foregoing directional loudspeaker box, wherein the hollow housing is provided with a spoiler blade between each two adjacent directional acoustic transmission holes that are arranged along the axial direction of the hollow housing. Each spoiler blade is so configured that the central axes of two corresponding adjacent directional acoustic transmission holes form different included angles with the central axis of the loudspeaker respectively, wherein the smaller the axial distance between a directional acoustic transmission hole and the loudspeaker, the larger the included angle formed by the central axis of the directional acoustic transmission hole with the central axis of the loudspeaker, and the larger the axial distance, the smaller the included angle. Due to compression by the spoiler blades and the walls of the directional acoustic transmission holes, the sound generated by the loudspeaker can propagate not only out of the hollow housing but also in different directions through the directional acoustic transmission holes.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a directional loudspeaker box having directional acoustic transmission holes. To facilitate description, the direction facing the lower left corner ofFIG. 2is defined as the front direction of a component; the direction facing the upper right corner ofFIG. 2, as the rear direction of the component; the direction facing the upper left corner ofFIG. 2, as the leftward direction of the component; and the direction facing the lower right corner ofFIG. 2, as the rightward direction of the component. As shown inFIGS. 2, 3A, and 3B, the directional loudspeaker box1includes a hollow housing11and a loudspeaker13. In the first embodiment, the hollow housing11is slightly barrel-shaped and is provided therein with a receiving space110for receiving the electronic elements (e.g., a sound source control circuit) required for normal operation of the directional loudspeaker box1. As the arrangement of such electronic elements is well known in the art, no further description is provided herein, and the drawings omit such electronic elements for the sake of simplicity.

With continued reference toFIGS. 2, 3A, and 3B, the front end of the hollow housing11is provided with a front opening111, and a peripheral portion of the hollow housing11that is adjacent to the front opening111is formed with a plurality of directional acoustic transmission holes12. Each directional acoustic transmission hole12penetrates the hollow housing11and is open on the inner and outer walls of the hollow housing11. Thus, the directional acoustic transmission holes12as well as the front opening111are in communication with the receiving space110. It should be pointed out that while the directional acoustic transmission holes12are depicted inFIG. 2as slits, they may in other embodiments of the present invention be circular, triangular, polygonal, wavy, or of other shapes to meet design requirements. Moreover, the directional acoustic transmission holes12may be arranged separately from one another or in an interconnected manner. The loudspeaker13is fixed in the hollow housing11and divides the receiving space110into a front acoustic cavity110A and a rear acoustic cavity110B. The front opening111and the directional acoustic transmission holes12correspond to the front acoustic cavity110A. As shown inFIGS. 3A and 3B, the front opening111has the same central axis as the loudspeaker13(i.e., the axis A1inFIG. 3B). Also, the loudspeaker13is electrically connected to the electronic elements in the hollow housing11in order to receive audio signals from the electronic elements and generate the corresponding sounds. In the first embodiment, the loudspeaker13has a membrane131facing the front acoustic cavity110A. The membrane131has a central axis coinciding with that of the front opening111and is located behind the directional acoustic transmission holes12so that the sound generated by the loudspeaker13can propagate out of the front end of the hollow housing11through the front opening111and the directional acoustic transmission holes12. As the hollow housing11is barrel-shaped and the loudspeaker13is located in the hollow housing11, an inner wall portion of the hollow housing11that is adjacent to the front opening111will compress the air flowing through the front opening111, and this compression enables the sound generated by the loudspeaker13to project outward over a great distance. Meanwhile, the directional acoustic transmission holes12contribute to enhancing the near-field sound effect.

The structure of the directional acoustic transmission holes12of the present invention is detailed below with reference toFIGS. 2 and 3A-3C. As shown in the drawings, the central axis of each directional acoustic transmission hole12and the central axis of the loudspeaker13form an included angle therebetween, wherein the included angle is a function of the axial distance between the acoustic transmission hole12and the loudspeaker13in the axial direction of the hollow housing11. InFIG. 3B, for example, the directional acoustic transmission holes12in the upper half of the hollow housing11are symmetric to and have the same structure as those in the lower half of the hollow housing11, and the directional acoustic transmission holes12in the left half of the hollow housing11are symmetric to and have the same structure as those in the right half of the hollow housing11. The axis A2inFIGS. 3B and 3Cis the central axis of the directional acoustic transmission hole12A. The axis A2of the directional acoustic transmission hole12A forms an included angle θ1with the axis A1of the loudspeaker13. The axis A3inFIG. 3Bis the central axis of the directional acoustic transmission hole12B. The axis A3of the directional acoustic transmission hole12B forms another included angle θ2with the axis A1of the loudspeaker13. As illustrated inFIGS. 3B and 3C, the axial distance between the central axis of the directional acoustic transmission hole12A and the central axis of the loudspeaker13is relatively small, so the included angle θ1corresponding to the directional acoustic transmission hole12A is relatively large (about 75˜90 degrees); the axial distance between the central axis of the directional acoustic transmission hole12B and the central axis of the loudspeaker13is relatively large, so the included angle θ2corresponding to the directional acoustic transmission hole12B is relatively small (about 30 degrees). When the sound generated by the loudspeaker13propagates outward through the front acoustic cavity110A, therefore, the directional acoustic transmission holes12A and12B guide the sound out of the front acoustic cavity110A in different directions respectively.

To increase the distance of sound projection from the directional loudspeaker box1, referring toFIGS. 2, 3A, and 3B, the hollow housing11has a larger inner diameter at the juncture between the front acoustic cavity110A and the rear acoustic cavity110B than in the other regions. In the first embodiment, the middle section of the hollow housing11has a larger inner diameter than the front section of the hollow housing11in order for the change in inner diameter to have the intended effect on the speed of airflow. The hollow housing11in the first embodiment is further provided therein with a spoiler portion15lying between the front opening111and the membrane131along the central axes thereof so as to form at least one compression channel150(i.e., the gap between the periphery of the spoiler portion15and the inner wall of the hollow housing11) in the front acoustic cavity110A. Thus, the airflow generated by vibrations of the membrane131will be compressed while passing through the space between the spoiler portion15and the corresponding inner wall portion of the hollow housing11and consequently be forced outward at high speed. In other words, the sound generated by the loudspeaker13will, together with the high-speed airflow, be subjected to such actions of the at least one compression channel150as reflection, compression, concentration, and release and propagate out of the front acoustic cavity110A through the front opening111; accordingly, the distance of acoustic transmission is effectively increased. It should be pointed out that, referring back toFIGS. 2, 3A, and 3B, the spoiler portion15may be a second loudspeaker having a smaller diameter and higher frequency than the loudspeaker13. The second loudspeaker is provided with a plurality of connecting plates151that are connected to the inner wall of the front acoustic cavity110A to form a plurality of compression channels150. The sound generated by both the loudspeaker13and the second loudspeaker will propagate out of the front acoustic cavity110A via the front opening111of the hollow housing11to satisfy user needs.

In the first embodiment, referring toFIGS. 2-4, each directional acoustic transmission hole12can be made in advance and then provided therein with at least one spoiler blade123to form the directional acoustic transmission hole12A or12B inFIG. 3B, wherein the spoiler blade123is configured in such a way (e.g., as having the inclined surface1231shown inFIGS. 3C and 4) that the central axes of two adjacent directional acoustic transmission holes12A and12B form different included angles with the central axis of the loudspeaker13. More specifically, the smaller the axial distance between a directional acoustic transmission hole to the loudspeaker, the larger the included angle between the central axes of the directional acoustic transmission hole and of the loudspeaker, and the larger the axial distance, the smaller the included angle. As air flowing through each directional acoustic transmission hole12is compressed jointly by the hole wall and the corresponding spoiler blade123and is guided by the inclined surface1231of the corresponding spoiler blade123, the sound propagating through each directional acoustic transmission hole12travels not only farther than without the corresponding spoiler blade123, but also in a different direction outward of the front acoustic cavity110A. In other embodiments of the present invention, however, it is feasible for each spoiler blade123to dispense with the inclined surface1231. Thanks to the angle between the direction in which each directional acoustic transmission hole12opens and the opening direction of the front opening111, the overall design of the directional loudspeaker box1provides higher sound quality by giving depth and transparency to the sound output from the directional loudspeaker box1and by projecting the sound farther and wider.

In the second embodiment of the present invention, referring toFIGS. 5 and 6, the directional loudspeaker box2includes a hollow housing21, a loudspeaker23, and a spoiler portion25, wherein the hollow housing21is slightly barrel-shaped and is provided therein with a receiving space210. In the second embodiment, the hollow housing21is assembled from a front housing21A and a rear housing21B, and yet the number of parts of the hollow housing21in other embodiments may vary according to product requirements. The front housing21A is provided with a front opening211at the front end and is peripherally provided with a plurality of directional acoustic transmission holes22each penetrating the front housing21A and opening on both the inner and outer walls thereof. The spoiler portion25is provided in the front housing21A and forms a plurality of compression channels in the front housing21A. The front opening211is in communication with the compression channels and the receiving space210while each directional acoustic transmission hole22is in communication with the corresponding compression channel and the receiving space210.

As shown inFIGS. 5 and 6, the loudspeaker23is provided in the rear housing21B and divides the receiving space210into a front acoustic cavity and a rear acoustic cavity. That is to say, in the second embodiment, the front acoustic cavity is formed in the front housing21A, and the rear acoustic cavity is formed in the rear housing21B. Once the front housing21A and the rear housing21B are assembled together, the membrane231of the loudspeaker23is located behind the directional acoustic transmission holes22. Moreover, in the second embodiment as shown inFIGS. 7 and 8, the inner wall of the hollow housing21is protrudingly provided with a spoiler plate221adjacent to each directional acoustic transmission hole22. Each spoiler plate221extends toward the front acoustic cavity and surrounds the inner periphery of the corresponding directional acoustic transmission hole22such that a directional spoiler channel221A is formed between each spoiler plate221and the corresponding directional acoustic transmission hole22. Each directional spoiler channel221A has one end in communication with the front acoustic cavity and the opposite end in communication with the corresponding directional acoustic transmission hole22. Thus, the sound generated by the loudspeaker23can travel through the front acoustic cavity into the directional spoiler channels221A and then propagate out of the front acoustic cavity in different projection directions (as indicated by the letter J inFIG. 8) through the directional acoustic transmission holes22, depending on the axial distance between each directional acoustic transmission hole22and the loudspeaker23, wherein the smaller the axial distance, the larger the angle of the projection direction with respect to the central axis of the loudspeaker23, and the larger the axial distance, the smaller the angle. In order to apply the directional acoustic transmission holes22of the present invention to various types of loudspeaker boxes, however, it is feasible for the directional acoustic transmission holes22in other embodiments to dispense with additional elements or structures.

The embodiment described above is but a preferred one of the present invention and does not impose limitation on the technical features of the invention. All equivalent changes based on the technical contents disclosed herein and readily conceivable by a person of ordinary skill in the art should fall within the scope of the present invention.