Patent Application
20160337749
The invention relates to a housing of a loudspeaker, and in particular, a high frequency transducer housing (“tweeter housing”) for use in a coaxial loudspeaker system.
Typically, a coaxial loudspeaker system consists of a high frequency transducer and one or more lower frequency transducers. The high frequency transducer can be mounted in front of or even within a lower frequency transducer.
Coaxial loudspeaker transducers make it possible to build 2 or 3 way loudspeaker system with smaller frontal area than conventional side by side transducers. The coaxial loudspeaker transducers also have an advantage of sound radiating from acoustically a single source for more even directivity pattern.
Disadvantage of the typical coaxial loudspeaker system is diffraction around the edges of the high frequency transducer housing. Diffraction of sound waves occurs when a sound wave encounter an obstacle that is comparable in size to the length of the sound wave. In a coaxial loudspeaker system, when a sound wave radiated from the diaphragm of a lower frequency transducer reaches the edge of high frequency transducer housing and is reflected by the edge of high frequency transducer housing, if the wavelength of the sound wave is comparable to the edge of the high frequency transducer housing, the reflected sound wave interferes with a subsequent sound wave with a similar wavelength propagating from the diaphragm of the lower frequency transducer. This interference between sound waves causes diffraction. The diffraction in turn causes irregular frequency response.
An objective of the present invention is to provide a high frequency transducer housing for a coaxial loudspeaker system to mitigate edge diffraction and to improve frequency response and sound radiation pattern of the sound waves radiated from a lower frequency transducer.
In an embodiment, there is provided a high frequency transducer housing for use in a coaxial loudspeaker system wherein at least one high frequency transducer is configured to be mounted with a second frequency transducer, the housing comprising:
a polygon having a plurality of sides;
a least one opening on the polygon for allowing sound waves radiated from the at least one high frequency loudspeaker pass through the housing; and
at least one edge on a side of polygon,
wherein the at least one edge is eccentric with a diaphragm of the second transducer.
In a further embodiment, there is provided a coaxial loudspeaker system, the coaxial loudspeaker system comprising at least one high frequency transducer that is configured to be mounted with a second frequency transducer, and a high frequency transducer housing for use in the coaxial loudspeaker system, the housing comprising:
a polygon having a plurality of sides;
a space on the polygon for allowing sound waves radiated from a high frequency loudspeaker pass through the housing; and
Particular embodiments of the present invention will now be described with reference to the drawings. It will be understood by the skilled reader, however, that various modifications to the embodiments described herein are possible. Such modifications are intended to fail within the scope of the present invention, which is described by the claims.
In the example of
As shown in
The edges 108 of the housing 104 have irregular shapes. The edges are arranged to have substantially continuously varying distances from the centre of the diaphragm 102 of the second frequency transducer 103 to different points of the edges, so that reflection of the sound wave does riot occur simultaneously, but is spread in time. This arrangement of the shapes of edges 108 reduces the effect of reflected wave superposition over direct wave and thus improves frequency response. The edges 108 of high frequency transducer housing 104 are eccentric with the diaphragm 102 of the low frequency transducer 103. The edges 108 may also be arranged asymmetrically to each other, for example, one edge of the housing 104 has no an opposing edge. The shape of the housing 104 may be a polygon 107 with substantially rounded edges 108. The edges 108 may be substantially concave or convex from the side of the polygon 107. In the example of
Due to the irregular shape of the edges 108 of the housing 104, some of the sound waves propagating from the diaphragm 102 of the second frequency transducer 103 reach the edges 108 at different times. As a result, the sound waves reached the edges 108 are also reflected from the edges 108 at different times. These differences in times reduce the effect of diffraction and improves frequency response and sound radiation pattern.
Dimensions of the edges 108 are substantially comparable in size to a quarter of the wavelength of the sound wave that is affected by the diffraction. For example, if anomaly due to diffraction appears around 3 kHz, the quarter wavelength is about 2.86 centimetres, and dimensions of the edges 108 of the housing are substantially around 2.86 centimetres.
The number of the edges 108 depends on the size of the sides of the polygon 107 of the high frequency transducer housing 104, and the wavelength of the sound wave that diffraction is required to be mitigated. The more sides the polygon 107 of the housing 104 has, the more edges the housing 104 may have. If the size of a side of the polygon 107 is big enough, the side of the polygon may have more than one rounded edges 108. As well, the high frequency transducer housing 104 may have more edges 108 if a sound affected by the diffraction has a shorter wavelength.
The numbers of the edges 108 can be determined after the shape of the housing 104, the size of the high frequency transducer housing 104, and the wavelength of the sound wave that is affected by the diffraction have been determined. The number of the edges 108 may be varied. On one hand, if the housing 104 has too few edges 108, the housing 104 will provide uneven directivity pattern; on the other hand, if the housing 104 has too many edges 108 so that the undulations become acoustically close to round edge baffle, the housing 104 will become less effective to reduce edge diffraction and to improve the frequency response and sound radiation pattern. Generally, odd number of edges 108 helps reduce addition of opposing edges reflections. For example, in
In another embodiment according to
The materials used to make the housing 104 may be metals that allow for adequate heat dissipation. For example, metals such as magnesium, aluminum, zinc, alloys thereof, etc. can be used to make the housing 104. The materials of the housing 104 may also be polymers. In the example of
The scope of the claims should not be limited by the embodiments set forth in the examples, but should be given the broadest interpretation consistent with the specification as a whole.
This application claims priority based on U.S. patent application Ser. No. 62/160,993 entitled “LOW DIFFRACTION TWEETER HOUSING” filed May 13, 2015, the subject matter of which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62160993 | May 2015 | US |
