Patent Application
20150195629
Not Applicable
Not Applicable
1. Technical Field
The present invention generally relates to loudspeakers, and more particularly, to passive acoustic radiators.
2. Related Art
Loudspeakers are universally known and utilized in audio systems for the reproduction of sound. Essentially, loudspeakers are transducers which convert electrical energy to acoustic energy. There are a wide variety of designs employing various operational principles, though the most common is the electro-dynamic variety, in which an electrical signal representative of the desired audio is applied to a voice coil wound around a bobbin and suspended between opposite poles of a magnet. The region between the poles is known as the air gap, and the magnetic field present therein interacts with the electrical current passed through the voice coil. The electromagnetic force moves the bobbin/voice coil along the air gap, and the displacement or movement thereof is controlled by the magnitude and direction of current in the coil and the resulting axial forces. The bobbin is also attached to a cone-shaped semi-rigid diaphragm, and the vibration of the bobbin is correspondingly transferred thereto. The base of the diaphragm is generally suspended from the rim of the loudspeaker basket, and provides lateral stability. The apex of the diaphragm generally includes a damper, also known in the art as a spider, which is a ring-shaped member having an interior edge that may be secured to the bobbin and an exterior edge that may be secured to the basket. The damper resiliently supports the bobbin at the respective predetermined static positions within the air gap without the voice coil contacting the surrounding surfaces of the yoke or the magnet.
In general, loudspeaker designs aim for the faithful re-creation of the sound or acoustic waveform represented by the electrical signal. The typical acoustic waveform is a combination of continuous waveforms of different magnitudes, frequencies, and phases, and unfortunately, a single loudspeaker driver cannot reproduce sounds across the entire audible frequency range. This is understood to due to the limitations imposed by weight and size of the diaphragm and bobbin. Thus, loudspeaker systems employ multiple drivers, each being configured for a particular frequency range. There may be a tweeter for high frequency sound reproduction in the range of approximately 2,000 to 20,000 Hz, a midrange driver which is capable of reproducing frequencies in the range of 300 to 5,000 Hz, and a woofer for bass/low frequency sound in the range of 40 to 1,000 Hz. Regardless of the frequency range or driver type, that is, whether the driver is classified as a tweeter, midrange, or woofer, the basic components of an electrodynamic loudspeaker are the same as discussed generally above.
There are speaker systems in which different range drivers are integrated into a single enclosure, as well systems with dedicated units for each driver or multiple drivers in the same frequency range. Particularly for the enhanced reproduction of the lowest bass sounds that cannot be produced clearly from smaller mid-range/tweeter units, subwoofers are employed. In order to generate the needed sound pressure levels at the lower frequency ranges, the woofer drivers are larger in size, with attendant increases in weight and electrical power requirements. For this reason, most subwoofers utilize an on-board amplifier that is also integrated into the enclosure.
Depending on the desired response, the subwoofer enclosure may be configured in a variety of different ways. One possible configuration is the sealed enclosure, whereby the back wave from the woofer driver is isolated within the enclosure. Alternatively, there are ported designs in which air (and attendant pressure waves thereof generated by the woofer driver) is allowed to escape the enclosure, resulting in greater efficiency and higher output levels. The enclosure typically defines an opening, to which a hollow tube is interfaced. Compared to sealed designs, ported designs tend to have a poorer transient response, and the port diameters, enclosure volume, tube length, and driver parameters must be meticulously tuned to achieve the best response.
A variation of the ported design involves the use of passive radiators substituted for the aforementioned ports. A passive radiator can be the same driver unit as that utilized for the woofer driver, but with the voice coils and magnets removed. The reciprocating movement of the electromagnetically driven primary driver causes pressure level fluctuations from the rear of the diaphragm, which in turn induces movement of the passive radiator diaphragm. Over conventional ported designs, passive radiators can output the same sound levels but with a much smaller enclosure footprint. Furthermore, the response of the active woofer driver can be dampened and the excursion of the diaphragm/surround can be reduced.
Aside from utilizing the woofer driver without voice coils and magnets, there are dedicated passive radiator designs that are comprised of a flat diaphragm suspended from an opening in the enclosure with a suspension/surround. Tuning of the passive radiation generally involves matching the weight of the diaphragm with that of the active woofer driver. However, conventional designs tend to induce a rolling or rotation transverse to the reciprocation axis of the diaphragm, causing flutter noise and other distortion of the output. Accordingly, there is a need in the art for an improved passive radiator.
Various embodiments of the present disclosure contemplate a passive acoustic radiator. There may be a forward radiating element that is defined by a forward front face and an opposed forward rear face. Furthermore, the forward radiating element may include a forward diaphragm that may be coupled to a forward surround that is defined by an annular raised side coinciding with the forward front face and an opposed annular trough side coinciding with the forward rear face. There may be a reverse radiating element that is similarly defined by a reverse front face and an opposed reverse rear face. The reverse radiating element may include a reverse diaphragm that is coupled to a reverse surround defined by an annular raised side coinciding with the reverse front face and an opposed annular trough side coinciding with the reverse rear face. The forward radiating element and the reverse radiating element may be attached to each other with the forward rear face of the forward radiating element being in an abutting relationship to the reverse rear face of the reverse radiating element. An annular open space may be defined at least partially by the respective trough sides of the forward and reverse radiating elements.
According to another embodiment, a passive radiator is disclosed. It may have a forward surround defined by a front surround surface and an opposed rear surround surface. Additionally, there may be a forward outer gasket that is defined by a front outer gasket surface attached to the rear surround surface of the forward surround, and an opposed rear outer gasket surface. The passive radiator may further include a forward diaphragm defined by a front diaphragm surface and an opposed rear diaphragm surface. The front diaphragm surface may be attached to the rear surround surface of the forward surround. There may further be a reverse surround that is defined by a front surround surface and an opposed rear surround surface. The passive radiator may also include a reverse outer gasket defined by a front outer gasket surface attached to the rear surround surface of the reverse surround, and an opposed rear outer gasket surface attached to the rear outer gasket surface of the forward outer gasket. There may also be a reverse diaphragm that is defined by a front diaphragm surface and an opposed rear diaphragm surface. The front diaphragm surface of the reverse diaphragm may be attached to the rear surround surface of the reverse surround, while the rear diaphragm surface of the reverse diaphragm may be attached to the rear diaphragm surface of the forward diaphragm. In one variation, the surrounds may be annular and characterized by an inner flange, and outer flange, and a cross-sectionally arcuate raised section therebetween, while in another variation, the surrounds may be characterized by an outer flange, and inner planar portion, and a cross-sectionally arcuate raised section therebetween.
Another embodiment further contemplates a passive radiator. There may be a forward surround that is defined by a front surround surface, an opposed rear surround surface, an outer flange portion, and an inner planar portion. There may also be a forward outer gasket that is defined by a front outer gasket surface and an opposed rear outer gasket surface that can be attached to the outer flange portion of the forward surround. The passive radiator may further include a forward diaphragm that is defined by a front diaphragm surface and an opposed rear diaphragm surface attached to the inner planar portion of the forward surround. Moreover, there may be a reverse surround that is defined by a front surround surface, an opposed rear surround surface attached to the rear surround surface of the forward surround, an outer flange portion, and an inner planar portion. The passive radiator may include a reverse outer gasket that is defined by a front outer gasket surface and an opposed rear outer gasket surface attached to the outer flange portion of the reverse surround. There may also be a reverse diaphragm that is defined by a front diaphragm surface and an opposed rear diaphragm surface attached to the inner planar portion of the reverse surround.
The presently contemplated embodiments will be best understood by reference to the following detailed description when read in conjunction with the accompanying drawings.
These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which:
Common reference numerals are used throughout the drawings and the detailed description to indicate the same elements.
The detailed description set forth below in connection with the appended drawings is intended as a description of the presently preferred embodiments of a passive radiator, and is not intended to represent the only form in which the present apparatus may be developed or utilized. The description sets forth the functions and features of the passive radiator in connection with the illustrated embodiment. It is to be understood, however, that the same or equivalent functions may be accomplished by different embodiments that are also intended to be encompassed within the present disclosure. It is further understood that the use of relational terms such as top, bottom, forward, reverse, front, rear and the like are used solely to distinguish one from another entity without necessarily requiring or implying any actual such relationship or order between such entities.
Referring now to
In general, the passive radiator 12 is understood to respond to the back pressure waves from the active woofer drivers 16 and reciprocate along a vibration axis z. The passive radiator 12 is understood to increase the efficiency of bass output for a given electrical amplification level because a substantially greater diaphragm surface area is being used to output sound. However, conventional passive radiators tend to exhibit off-axis rotation that causes flutter and other sonic distortion, and so improvements in this regard are contemplated in the various exemplary embodiments of the passive radiator 12, including a first embodiment 12a shown in
The passive radiator 12 is generally comprised of a forward radiating element 30 and a reverse radiating element 32. Although each depiction of the various embodiments of the passive radiator 12 shows a rounded rectangle profile, this is by way of example only and not of limitation. Any other suitable profile may be substituted without departing from the present disclosure. As will be discussed in further detail, the forward radiating element 30 and the reverse radiating element 32 may be identically configured, and the terms forward and reverse are utilized for distinguishing one radiating element from the other without requiring any particular one to be facing forward/outward or reverse/inward relative to the enclosure 14. The forward radiating element 30 is defined by a forward front face 34 and an opposed forward rear face 36. Additionally, the forward radiating element 30 includes a forward diaphragm 38 that is coupled to a forward surround 40.
The forward surround 40 is understood to be defined by an annular raised side 42 coinciding with the forward front face 34, that is, the annular raised side 42 is part of what defines the forward front face 34 of the more broadly described forward radiating element 30. Furthermore, the forward surround 40 is defined by an opposed annular trough side 44 coinciding with the forward rear face 36, which, again, is understood to refer to the annular trough side 44 being a part of what defines the forward rear face 36.
The reverse radiating element 32 is similarly defined by a reverse front face 46 and an opposed reverse rear face 48. There is also a reverse diaphragm 50 that is coupled to a reverse surround 52, which in turn is defined by an annular raised side 56 and an opposed annular trough side 56. The annular raised side 56 is understood to coincide with the reverse front face 46, while the annular trough side 56 is understood to coincide with the reverse rear face 48.
In accordance with various embodiments of the present disclosure, the forward radiating element 30 is attached to the reverse radiating element 32. More particularly, the forward rear face 36 of the forward radiating element 30 is in an abutting relationship to the reverse rear face 48 of the reverse radiating element 32. The forward radiating element 30 and the reverse radiating element, and in particular the annular trough sides 44, 56 at least partially define an open space 58 within the interior of the passive radiator 12. The forward surround 40 and the reverse surround 52 are understood to be constructed of resilient yet flexible material that allows limited movement or reciprocation of the diaphragms 38, 50 along an axis z-z. In accordance with one preferred, though optional embodiment of the present disclosure, the thickness of the surrounds 40, 52 is 0.3 mm. The forward and reverse surrounds 40, 52 that face each other in the illustrated configuration are understood to minimize rotation that is transverse to the y-y axis.
Having considered the features that are common to the three disclosed embodiments of the passive radiator 12a-12c, additional features that are specific to each will now be described. Again,
As indicated above, the forward surround 40 and the reverse surround 52 have a conventional annular configuration and include an outer flange 68 and an inner flange 70 each having a top surface 72 and an opposed bottom surface 74. Interposed between the outer flange 68 and the inner flange 70 is a cross-sectionally arcuate raised section 69. The semi-circular profile of the arcuate raised section 69 as shown in this and other embodiments is by way of example only and not of limitation, and any other suitable profile known in the art may be substituted without departing from the present invention. The top surface 72 may also be referred to as a front surround surface, while the bottom surface 74 may also be referred to as a bottom surround surface. In this context, the front face 60, e.g., the front diaphragm surface of the forward diaphragm 38, attaches to the bottom surface 74 of the forward surround 40. Likewise, the front face 60, e.g., the front diaphragm surface of the reverse diaphragm 50 attaches to and abuts the bottom surface 74 of the reverse surround 52.
With the annular configuration of the forward surround 40 and the reverse surround 52, in accordance with the first embodiment of the passive radiator 12a, it is contemplated that the respective inner flange 70 is what attaches to the diaphragms 38, 50. Because the inner flange 70 does not extend the entire interior area otherwise occupied by the diaphragms 38, 50, only a limited segment thereof is understood to be attached to the inner flange 70. That is, at least a part of the front face 60, 64 is attached to the inner flange 70 of the forward and reverse surrounds 40, 52, respectively.
Besides the abutting diaphragms 38, 50, the first embodiment of the passive radiator 12a includes a forward outer gasket 76 and a reverse outer gasket 78, both of which are defined by a front outer gasket surface 80 and a rear outer gasket surface 82. More particularly, the front outer gasket surface 80 of the forward outer gasket 76 is attached to the bottom surface 74 of the outer flange 68 of the forward surround 40, while the rear outer gasket surfaces 82 of the forward and reverse outer gaskets 76, 78 are attached to each other.
Like the first embodiment 12a, the rear face 62 of the forward diaphragm 38 abuts against the rear face 66 of the reverse diaphragm 50. With the second embodiment 12b, however, a substantial entirety of the front face 60 of the forward diaphragm 38 abuts against the planar inner section 90 of the forward surround 84, and a substantial entirety of the front face 60 of the reverse diaphragm 50 abuts against the planar inner section 90 of the reverse surround 86.
The same forward and reverse outer gaskets 76, 78 are each defined by the front outer gasket surface 80 and the rear outer gasket surface 82. The front outer gasket surface 80 of the forward outer gasket 76 is attached to and abuts against the bottom surface 94 of the outer flange 88 of the second embodiment of the forward surround 84. Along these lines, the front outer gasket surface 80 of the reverse outer gasket 78 is attached to and abuts against the bottom surface 94 of the outer flange 88 of the second embodiment of the reverse surround 86. Again, the respective rear outer gasket surfaces 82 of the forward outer gasket 76 and the reverse outer gasket 78 abut against each other.
With reference to
In accordance with the third embodiment 12c, the forward surround 84 and the reverse surround 86 are attached to each other, and therefore at least partially define the abutting relationship of the forward radiating element 30 and the reverse radiating element 32. In order to secure the bottom surface 94 of the forward surround 84 and the bottom surface 94 of the reverse surround 86, glue may be utilized.
The diaphragms 38, 50 are exposed and attached only to the planar inner section 90 of the surrounds 84, 86, respectively. Again, the forward diaphragm 38 is defined by the front face 60 and the opposed rear face 62, and the reverse diaphragm 50 is defined by the front face 64 and the opposed rear face 66. The rear face 62 of the forward diaphragm 38 abuts against the top surface 92 of the forward surround 84, and the rear face 66 of the reverse diaphragm 50 abuts against the top surface 92 of the reverse surround 86. Thus, the front face 60 of the forward diaphragm 38 defines the forward front face 34 of the forward radiating element 30, while the bottom surface 94 of the forward diaphragm 38 defines the forward rear face 36 of the forward radiating element 30. Similarly, the front face 64 of the reverse diaphragm 50 defines the reverse front face 46 of the reverse radiating element 32, and the bottom surface 94 of the reverse diaphragm 50 defines the reverse rear face 48 of the reverse rear face 48 of the reverse diaphragm 50.
The forward outer gasket 76 and the reverse outer gasket 78 are likewise attached to the respective top surfaces 92 of the forward surround 84 and reverse surround 86. Both of the outer gaskets 76, 78 are further defined by the front outer gasket surface 80 and the opposed rear outer gasket surface 82. The rear outer gasket surfaces 82 thus abut against the respective top surfaces 92 of the forward surround 84 and the reverse surround 86. The front outer gasket surfaces 80 also at least partially define the forward front face 34 of the forward radiating element 30 and the reverse front face 46 of the reverse radiating element 32, respectively.
The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the passive radiator. In this regard, no attempt is made to show more details than is necessary for a fundamental understanding of the disclosure, the description taken with the drawings making apparent to those skilled in the art how the several forms of the presently disclosed methods may be embodied in practice.
