Patent Grant
10708694
An embodiment of the invention is directed to a transducer surround with improved performance, more specifically a surround having continuous corner corrugations with a particular orientation to achieve improved linear stiffness and reduced fatigue. Other embodiments are also described and claimed.
Whether listening to an MP3 player while traveling, or to a high-fidelity stereo system at home, consumers are increasingly choosing intra-canal and intra-concha earphones for their listening pleasure. Both types of electro-acoustic transducer devices have a relatively low profile housing that contains a receiver or driver (an earpiece speaker). The low profile housing provides convenience for the wearer, while also providing very good sound quality.
These devices, however, do not have sufficient space to house high fidelity speakers. This is also true for portable personal computers such as laptop, notebook, and tablet computers, and, to a lesser extent, desktop personal computers with built-in speakers. Such devices typically require speaker enclosures or boxes that have a relatively low rise (e.g., height as defined along the z-axis) and small back volume, as compared to, for instance, stand alone high fidelity speakers and dedicated digital music systems for handheld media players. Many of these devices use what are commonly referred to as “micro-speakers.” Micro-speakers are a miniaturized version of a loudspeaker, which use a moving coil motor to drive sound output. The moving coil motor may include a low profile diaphragm (or sound radiating surface) assembly, including a sound radiating surface and a suspension (or surround), a voice coil suspended from the sound radiating surface and a magnet assembly positioned within an enclosure. The input of an electrical audio signal to the moving coil causes the sound radiating surface to vibrate axially thereby creating pressure waves outside the driver enclosure. The suspension surrounds and suspends the sound radiating surface within the enclosure and allows it to vibrate axially.
An embodiment of the invention is a surround for suspending a diaphragm within a transducer which has a geometry that results in improved acoustic performance of the transducer. More specifically, the surround geometry results in improved linear stiffness with less likelihood of fatigue over time due to stress created by the pistonic (or z-axis) motion of the diaphragm. Representatively, in the case of a single suspension transducer, a surround performs many functionalities such as positioning the voice coil within the air gap of the magnet assembly, sealing the diaphragm to the enclosure to acoustically isolate the front side from the back side, contributing to the stiffness and influencing the resonance frequency of the transducer. Thus, during operation, it is important that the surround deform in a controlled way to, for example, prevent the voice coil from hitting rigid components within the transducer and to maintain the most linear stiffness possible within the displacement extremes of the diaphragm. The material stiffness and the stiffness defined by the surround geometry contribute to the stresses occurring within the material, and therefore play an important role in both fatigue and stiffness linearity. In the case of a micro-speaker, the surround may be rectangular to increase the radiating surface. Due to this rectangular shape, however, different sections of the surround have different deformation characteristics as the surround moves away from the rest position (e.g. due to diaphragm vibrations), which in turn, subjects certain areas of the surround to more stress than others. For example, the most complicated deformation occurs at the corners of the surround. In the corners, as the voice coil moves out of the air gap (coil-out direction), the highest point of the surround (in the case of a surround having an arcuate shape) tries to increase in radius and move away from the center of the surround. As the voice coil moves into the air gap (coil-in direction) the highest point of the surround tries to reduce in radius and moves toward the center of the surround. These radial changes introduce circumferential stresses over the surround geometry, and may lead to non linear behavior and fatigue development over time. The present invention reduces this non linear behavior and fatigue over time by introducing an improved corner geometry in which a number of continuous corrugations are formed in each corner of the surround and in a particular orientation with respect to a maximum stress line across each corner.
Representatively, in one embodiment, the invention is directed to a transducer having an enclosure separating a surrounding environment from an encased space, a diaphragm positioned within the encased space, a surround connecting the diaphragm to the enclosure, a voice coil extending from one side of the diaphragm and a magnet assembly having a magnetic gap (or air gap) aligned with the voice coil. In one embodiment, the transducer is an electroacoustic transducer such as a loudspeaker, more specifically, a micro-speaker. The term “micro-speaker” as used herein is intended to refer to a speaker having a size range (e.g., a diameter or longest dimension) of from about 10 mm to 75 mm, in some cases, within a size range of from 10 mm to 20 mm. Returning now to the surround, the surround may have a corner section and a plurality of corrugations formed within the corner section. Each corrugation of the plurality of corrugations may have a length dimension perpendicular to a line of maximum stress across the corner section.
More specifically, in one embodiment, the invention is directed to a transducer assembly including a frame, a diaphragm positioned within the frame, a surround connecting the diaphragm to the frame, a voice coil extending from one side of the diaphragm, and a magnet assembly having a magnetic gap aligned with the voice coil. The surround may include a corner section and a plurality of corrugations formed within the corner section. Each corrugation of the plurality of corrugations may have a length dimension perpendicular to a line of maximum stress intersecting a radial axis of the corner section. In some cases, the transducer is a micro-speaker, and the line of maximum stress is parallel to a line tangential to an interior arcuate edge of the corner section. In addition, in some embodiments, the line of maximum stress may be perpendicular to the radial axis. In addition, the line of maximum stress may be a region across the corner determined to be subject to a maximum level of deformation stress based on a finite element analysis of the surround corner. Still further, the length dimension of each corrugation may be parallel to the radial axis. The radial axis may be an axis that bisects the corner section, and the line of maximum stress intersects the radial axis at a point that is between an inner edge and an outer edge of the corner section. In some cases, the plurality of corrugations may include a continuous second derivative and all other derivatives are continuous. Each corrugation may extend from an inner edge to an outer edge of the corner section. The surround may be a single, substantially solid membrane.
In other embodiments, the invention is directed to a surround for suspending a transducer diaphragm. The surround may include a first membrane section having a length dimension parallel to a first axis, a second membrane section having a length dimension parallel to a second axis, a corner membrane section at an intersection between the first axis of the first membrane section and the second axis of the second membrane section, wherein the first axis and the second axis intersect to form a ninety degree angle and the corner membrane section comprises an arcuate inner edge, and a number of continuous corrugations within the corner membrane section. Each corrugation may have a length dimension perpendicular to a line tangential to the arcuate inner edge of the corner membrane section. In addition, the continuous corrugations may include a series of uninterrupted ribs and furrows. In addition, in some embodiments, the corrugations may have a curved cross-sectional shape. In addition, the length dimension of the corrugations may be perpendicular to a line of maximum stress that is parallel to the line tangential to the arcuate inner edge and intersects a center of the corner membrane section. Still further, the length dimensions of each corrugation may be parallel to one another, and in some cases, may run from an inner edge to an outer edge of the corner membrane section.
In still further embodiments, the invention is directed to a micro-speaker surround having a membrane for connecting a diaphragm to an enclosure, the membrane having a first pair of parallel side sections, a second pair of parallel side sections, and a set of corner sections connecting the first pair of parallel side sections and the second pair of parallel side sections; and a plurality of continuous corrugations within each of the corner sections of the set of corner sections, and wherein each of the corrugations of the plurality of continuous corrugations within each of the corner sections have a length dimension perpendicular to a line of maximum stress intersecting a radial axis of their respective corner section. In some cases, the first set of parallel sides may be longer than the second set of parallel sides. Still further, the line of maximum stress may intersect the radial axis at an angle of ninety degrees. In addition, the plurality of corrugations within adjacent corner sections may be spaced a distance apart such that they do not overlap. Still further, the plurality of corrugations within each of the corner sections may be parallel to the radial axis of their respective corner section.
The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary.
The embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one.
In this section we shall explain several preferred embodiments of this invention with reference to the appended drawings. Whenever the shapes, relative positions and other aspects of the parts described in the embodiments are not clearly defined, the scope of the invention is not limited only to the parts shown, which are meant merely for the purpose of illustration. Also, while numerous details are set forth, it is understood that some embodiments of the invention may be practiced without these details. In other instances, well-known structures and techniques have not been shown in detail so as not to obscure the understanding of this description.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper”, and the like may be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising” specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.
The terms “or” and “and/or” as used herein are to be interpreted as inclusive or meaning any one or any combination. Therefore, “A, B or C” or “A, B and/or C” mean “any of the following: A; B; C; A and B; A and C; B and C; A, B and C.” An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive.
Transducer 100 may include a frame 102, which may be part of a transducer enclosure or box whose height (or rise) and speaker back volume (also referred to as an acoustic chamber) are considered to be relatively small. For example, the enclosure height or rise may be in the range of about 1 millimeter (mm) to about 10 mm. The concepts described here, however, need not be limited to transducer enclosures whose rises are within these ranges. Each of the components of transducer 100, for example components of a speaker assembly as will be discussed herein, may be positioned within, or otherwise connected to, frame 102.
In one embodiment, one of the components of transducer 100 (e.g., speaker assembly components) positioned within frame 102 may include a sound radiating surface (SRS) 104. The SRS 104 may also be referred to herein as an acoustic radiator, a sound radiator or a diaphragm. SRS 104 may be any type of flexible membrane capable of vibrating in response to an acoustic signal to produce acoustic or sound waves. For example, SRS 104 may include a top face 104A, which generates sound to be output to a user, and a bottom face 104B, which is acoustically isolated from the top face 104A, so that any acoustic or sound waves generated by the bottom face 104B do not interfere with those from the top face 104A. The top face 104A may be considered the “top” face because it faces, or includes a surface substantially parallel to, a top side of frame 102 (not shown). Similarly, the bottom face 104B may be considered a “bottom” face because it faces, or includes a surface substantially parallel to, a bottom surface of frame 102. Although shown substantially planar, in some embodiments, SRS 104 may have an out-of-plane region for geometric stiffening. SRS 104 may, for example, be made of a single layer of material, or multiple layers of material for increased stiffness. For example, SRS 104 made of a polyester material such as polyethylene naphthalate (PEN) or, one or more layers of a PEN thermofoil.
SRS 104 may be suspended within frame 102 by a suspension member 106, also referred to herein as a suspension or surround. Suspension member 106 allows for a substantially vertical or pistonic movement of SRS 104, that is in a substantially up and down direction as illustrated by arrow 124, relative to fixed frame 102. In one embodiment, suspension member 106 may have an inner edge 106A connected to an outer edge of SRS 104 (e.g. by an adhesive or molded) and an outer edge 106B attached to frame 102 to suspend SRS 104 within frame 102. Suspension member 106 may be one continuous membrane which surrounds the SRS 104. For example, in one embodiment, SRS 104 may have a rectangular or square shaped profile. Suspension member 106, in turn, may be a similarly shaped square or rectangular membrane, but with an open center to accommodate SRS 104 such that it surrounds SRS 104. In addition, suspension member 106 may have a corner geometry to improve non linearity by improving linear stiffness, as well as reduce fatigue, as will be discussed in more detail in reference to
In some embodiments, suspension member 106 may further provide a seal between SRS 104 and frame 102. This seal may prevent acoustic cancellation and water ingress beyond (e.g., below) SRS 104 and therefore prevents any water, which may unintentionally enter transducer 100, from damaging the various electronic components and circuitry associated with transducer 100 (e.g., a voice coil). For example, suspension member 106 may be a membrane made of any compliant material that is sufficiently flexible to allow movement of SRS 104 in order to produce acoustic or sound waves. Representatively, suspension member 106 may be made of a polyester material such as polyethylene naphthalate (PEN), or a silicone. The term “membrane” as used herein is intended to refer to a relatively thin, pliable, sheet of material that can occupy an entire space between SRS 104 and frame 102, and provide an acoustic and/or water tight seal.
Transducer 100 may further include a voice coil 110 positioned along a bottom face 104B of SRS 104 (e.g., a face of SRS 104 facing magnet assembly 114). For example, in one embodiment, voice coil 110 may include a pre-wound coil assembly (which includes the wire coil held in its intended position by a lacquer or other adhesive material), which is wrapped around a bobbin or former 112. The end of the former 112 may be directly attached to the bottom face 104B of SRS 104, such as by chemical bonding or the like. In another embodiment, former 112 may be omitted, and voice coil 110 may be directly attached to the bottom face 104B of SRS 104. In still further embodiments, the former 112 or voice coil 110 may instead be attached directly to the bottom face of suspension member 106. In one embodiment, voice coil 110 may have a similar profile and shape to that of SRS 104. For example, where SRS 104 has a square or rectangular shape, voice coil 110 may also have a similar shape. For example, voice coil 110 may have a substantially rectangular or square shape. Although not shown, voice coil 110 may further have electrical connections to a pair of terminals through which an input audio signal is received, in response to which voice coil 110 produces a changing magnetic field that interacts with the magnetic field produced by magnet assembly 114 for providing a driving mechanism for transducer 100.
Magnet assembly 114 may be positioned along a bottom side of frame 102 or otherwise below SRS 104. Magnet assembly 114 may include a magnet 116 (e.g., a NdFeB magnet), with a top plate 118 and a yoke 120 for guiding a magnetic circuit generated by magnet 116 across gap 122. A one-magnet embodiment is shown here, although multi-magnet motors are also contemplated.
The specific features of suspension member 106 that allow for improved linear stiffness and fatigue will now be discussed in reference to
Corners 202A-202D may be considered the regions or portions of suspension member 106 where each of sides 206A-206D intersect, or said another way, where each of axes 204A-204D intersect. In some embodiments, axes 204A and 204C may be perpendicular to axes 204B and 204D such that a right or ninety degree angle is formed at their point of intersection, as shown. As previously discussed, due to these ninety degree angles, corners 202A-202D can be subjected to particularly complicated deformation characteristics as SRS 104 vibrates, which in turn leads to increased stress at these regions. These complicated deformation characteristics will now be discussed in reference to
Representatively,
More specifically, as shown in
These radial and/or circumferential changes introduce stresses over the surround geometry, particularly in the circumferential direction, with the most stress being found along a maximum stress path across the corner. The maximum stress path or line can be calculated using a standard finite element analysis based on the selected material (having a particular elasticity), size of the corner and maximum deflection or excursion. It should further be understood that the maximum stress path or line referred to herein is calculated during manufacturing of the surround, and is therefore calculated prior to forming the “arcuate” or “rolled” region shown in
In this aspect, the actual location of the region of maximum stress illustrated by line 304 can be defined in various ways. For example, in the case of a micro-speaker, the maximum stress path or line 304 of the suspension member corner 202 can be defined as a line of stress that crosses the center point 302 of the corner, and is parallel to, and offset from, a line 310 that is tangential to the interior arcuate surface 308 of corner 202. The center point 302 can be defined, for example, as the region halfway between the inner and out edges of corner 202, along radius (r). In addition, since the maximum stress path or line 304 may be parallel to the tangential line 310 of corner 202 as shown, the maximum stress path or line 304 may also be referred to herein as a tangential line which is offset with respect to the corner interior arcuate surface 308. In addition, as can be seen from
These circumferential stresses along the maximum stress path or line 304 can be the main cause of non-linear behavior and fatigue development. To alleviate this stress, and in turn reduce non-linear behavior and fatigue development, a number of ribs or corrugations having a particular orientation with respect to this region of maximum stress are introduced into the suspension member corners. In particular, returning now to
The particular orientation and structure of the corrugations will now be discussed in reference to
It has been found that when the corrugations 208 are oriented perpendicular to the maximum stress line 304 at each corner as described herein, as opposed to at another angle, the corrugations 208 absorb the circumferential and radial deformations during diaphragm excursion more evenly. This, in turn, helps to restore linearity and reduce surround fatigue over time. For example,
In addition to the orientation of corrugations 208, it is further important in achieving a reduction in fatigue and improved linearity that corrugations 208 within each of their respective corners 202A-202D are continuous and smooth. To illustrate this aspect,
Electronic device 900 can include, for example, power supply 902, storage 904, signal processor 906, memory 908, processor 910, communications circuitry 912, and input/output circuitry 914. In some embodiments, electronic device 900 can include more than one of each component of circuitry, but for the sake of simplicity, only one of each is shown in
Power supply 902 can provide power to the components of electronic device 900. In some embodiments, power supply 902 can be coupled to a power grid such as, for example, a wall outlet. In some embodiments, power supply 902 can include one or more batteries for providing power to earphones, headphones or other type of electronic device associated with the headphone. As another example, power supply 902 can be configured to generate power from a natural source (e.g., solar power using solar cells).
Storage 904 can include, for example, a hard-drive, flash memory, cache, ROM, and/or RAM. Additionally, storage 904 can be local to and/or remote from electronic device 900. For example, storage 904 can include an integrated storage medium, removable storage medium, storage space on a remote server, wireless storage medium, or any combination thereof. Furthermore, storage 904 can store data such as, for example, system data, user profile data, and any other relevant data.
Signal processor 906 can be, for example a digital signal processor, used for real-time processing of digital signals that are converted from analog signals by, for example, input/output circuitry 914. After processing of the digital signals has been completed, the digital signals could then be converted back into analog signals.
Memory 908 can include any form of temporary memory such as RAM, buffers, and/or cache. Memory 908 can also be used for storing data used to operate electronic device applications (e.g., operation system instructions).
In addition to signal processor 906, electronic device 900 can additionally contain general processor 910. Processor 910 can be capable of interpreting system instructions and processing data. For example, processor 910 can be capable of executing instructions or programs such as system applications, firmware applications, and/or any other application. Additionally, processor 910 has the capability to execute instructions in order to communicate with any or all of the components of electronic device 900.
Communications circuitry 912 may be any suitable communications circuitry operative to initiate a communications request, connect to a communications network, and/or to transmit communications data to one or more servers or devices within the communications network. For example, communications circuitry 912 may support one or more of Wi-Fi (e.g., a 802.11 protocol), Bluetooth®, high frequency systems, infrared, GSM, GSM plus EDGE, CDMA, or any other communication protocol and/or any combination thereof.
Input/output circuitry 914 can convert (and encode/decode, if necessary) analog signals and other signals (e.g., physical contact inputs, physical movements, analog audio signals, etc.) into digital data. Input/output circuitry 914 can also convert digital data into any other type of signal. The digital data can be provided to and received from processor 910, storage 904, memory 908, signal processor 906, or any other component of electronic device 900. Input/output circuitry 914 can be used to interface with any suitable input or output devices, such as, for example, a microphone. Furthermore, electronic device 900 can include specialized input circuitry associated with input devices such as, for example, one or more proximity sensors, accelerometers, etc. Electronic device 900 can also include specialized output circuitry associated with output devices such as, for example, one or more speakers, earphones, etc.
Lastly, bus 916 can provide a data transfer path for transferring data to, from, or between processor 910, storage 904, memory 908, communications circuitry 912, and any other component included in electronic device 900. Although bus 916 is illustrated as a single component in
While certain embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that the invention is not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those of ordinary skill in the art. The description is thus to be regarded as illustrative instead of limiting.
This application claims the benefit of the earlier filing date of U.S. Provisional Patent Application No. 62/557,076, filed Sep. 11, 2017 and incorporated herein by reference.
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