Speaker including ultra-thin transducer

Abstract

Provided is a speaker including a transducer. The speaker includes: a diaphragm with a hole; a voice coil arranged at least partially in the hole; and a column structure arranged at least partially in the voice coil. The voice coil has a ring shape with an outer horizontal width and an inner horizontal width, and the outer horizontal width is equal to or less than the first horizontal width of the hole.

Description

TECHNICAL FIELD

[0001] One or more embodiments of the present disclosure generally relate to a speaker, and more particularly, to a speaker including a slim acoustic transducer that has a diaphragm including a hole.BACKGROUND ART

[0002] Televisions, notebook computers, and mobile phones have increasingly smaller thicknesses, but there is still demand for better sound quality (for example, more lower pitched tone output). To produce low-frequency sound (for example, bass), loudspeakers need to move a lot of air, which may be achieved by having large surface areas or by the large movement of diaphragms. Large surface areas of thin transducers are prone to bending or rocking, and thus, distortion and other mechanical issues occur.

[0003] Often, it is not possible to expose diaphragms. Instead, the sound needs to be radiated through narrow slots, which increase the total built heights (thicknesses) of acoustic modules. Advantages of slots loading transducers include avoiding being touched and also include minimizing interference with industrial design. However, slots loading thin transducers are more prone to rocking because the acoustic load on diaphragms is asymmetric. Publication JP 360028400 A relates to a dynamic speaker including a diaphragm and magnets disposed through an aperture in the diaphragm, publication DE 4317775 A1 relates to a loudspeaker with magnets arranged in the middle of a flat membrane for actuating the membrane vertically, and publication EP 0942626 A2 relates to a speaker with a flat membrane with an aperture on which a voice coil is affixed, and a magnets assembly is placed inside the aperture.DESCRIPTION OF EMBODIMENTSTECHNICAL PROBLEM

[0004] Example embodiments of the present disclosure provide a speaker including a slim transducer with a diaphragm including a hole.SOLUTION TO PROBLEM

[0005] The present invention is set out in the appended set of claims. A speaker is defined according to independent claim 1. Other aspects of the invention are defined according to the dependent claims.ADVANTAGEOUS EFFECTS OF DISCLOSURE

[0006] A speaker including a transducer, according to an example embodiment of the present disclosure, may have a slim structure. A transducer according to an example embodiment of the present disclosure may improve sound quality by reducing distortion.BRIEF DESCRIPTION OF DRAWINGS

[0007] FIG. 1 illustrates a cross-sectional view of a flat micro-speaker according to a comparison example. FIG. 2A illustrates a cross-sectional view of an example ultra-thin transducer according to an example useful for understanding the present invention. FIG. 2B illustrates a cross-sectional view of an ultra-thin transducer showing an example magnetic flux, according to an example useful for understanding the present invention. FIG. 3 is a cross-sectional view of a slot-loaded ultra-thin transducer showing top venting and bottom venting, according to an example useful for understanding the present invention. FIG. 4 is a cross-sectional view of a slot-loaded ultra-thin transducer showing asymmetric pressure on a diaphragm causing rocking motion, according to an example useful for understanding the present invention. FIGS. 5A to 5G respectively illustrate plan views of slot-loaded ultra-thin transducers with various air-flow venting, according to an example useful for understanding the present invention. FIG. 6 illustrates a graph of the propensity for rocking motion versus frequency for the examples in FIGS. 5A to 5G, according to an example useful for understanding the present invention. FIG. 7 illustrates a graph of the propensity for sound pressure level (SPL) versus frequency for the examples in FIGS. 5A to 5G, according to an example useful for understanding the present invention. FIG. 8A is a cross-sectional view of an ultra-thin transducer with a planar diaphragm, according to an example useful for understanding the present invention. FIG. 8B is a cross-sectional view of an ultra-thin transducer with a convex angled diaphragm, according to an example useful for understanding the present invention. FIG. 8C is a cross-sectional view of an ultra-thin transducer with a concave angled diaphragm, according to an example useful for understanding the present invention. FIG. 8D is a cross-sectional view of an ultra-thin transducer with a planar diaphragm and an outer suspension, according to an example useful for understanding the present invention. FIG. 8E is a cross-sectional view of an ultra-thin transducer with a structural diaphragm and an outer suspension, according to an example useful for understanding the present invention. FIG. 8F is a cross-sectional view of an ultra-thin transducer with an alternative-shaped voice coil, a structural diaphragm, and an outer suspension, according to an example useful for understanding the present invention. FIG. 8G is a cross-sectional view of an ultra-thin transducer with another alternative-shaped voice coil, a structural diaphragm, and an outer suspension, according to an example useful for understanding the present invention. FIG. 8H is a cross-sectional view of an ultra-thin transducer with a planar diaphragm and an inner suspension, according to an example useful for understanding the present invention. FIG. 8I is a cross-sectional view of an ultra-thin transducer, which has a planar diaphragm, a top plate, and a bottom plate and is configured for slot radiation, according to an example useful for understanding the present invention. FIG. 8J is a cross-sectional view of an ultra-thin transducer with a planar diaphragm and a ferrofluid seal, according to an example useful for understanding the present invention. FIG. 8K is a cross-sectional view of an ultra-thin transducer with a planar diaphragm and a grease seal, according to an example useful for understanding the present invention. FIG. 8L is a cross-sectional view of an ultra-thin transducer with a planar diaphragm, a top plate, and a bottom plate, according to an example useful for understanding the present invention. FIG. 8M is a cross-sectional view of an ultra-thin transducer with a planar diaphragm, a perforated top plate, and a perforated bottom plate, according to an embodiment of the present disclosure. FIG. 8N is a cross-sectional view of an ultra-thin transducer, which has a planar diaphragm and is configured for slot radiation, according to an example useful for understanding the present invention. FIG. 8O is a cross-sectional view of an ultra-thin transducer, which has a planar diaphragm, a top plate, and a bottom plate and is configured for slot radiation, according to an example useful for understanding the present invention. FIG. 9A is a cross-sectional view of a transducer, which has a planar diaphragm and is configured for slot radiation, according to the related art. FIG. 9B is a cross-sectional view of an ultra-thin transducer, which has a planar diaphragm and is configured for slot radiation, according to an example useful for understanding the present invention. FIG. 10A is a cross-sectional view of a transducer, which has a planar diaphragm and is configured for direct radiation, according to the related art. FIG. 10B is a cross-sectional view of an ultra-thin transducer, which has a planar diaphragm and is configured for direct radiation, according to an example useful for understanding the present invention. FIG. 11A is a cross-sectional view of an ultra-thin transducer with an inner surround to assist in preventing short circuiting, according to an example useful for understanding the present invention. FIG. 11B is a cross-sectional view of an ultra-thin transducer with a pressurizable material to prevent acoustic short circuiting, according to an example useful for understanding the present invention. FIG. 11C is a cross-sectional view of an ultra-thin transducer with a ferrofluid seal, according to an example useful for understanding the present invention. FIG. 12A is a top perspective view of an ultra-thin transducer with a top plate, according to an example useful for understanding the present invention. FIG. 12B is a top perspective view of the ultra-thin transducer of FIG. 12A with the top plate removed, according to an example useful for understanding the present invention. FIG. 12C is a cross-sectional view of the ultra-thin transducer of FIGS. 12A and 12B, according to an example useful for understanding the present invention. FIG. 13 is a top perspective view of an ultra-thin transducer with a perforated top plate, according to an example embodiment of the present disclosure. FIG. 14 illustrates an ultra-thin transducer with an elliptical diaphragm, according to an example useful for understanding the present invention.

[0008] One or more embodiments of the present disclosure relate to a speaker including a transducer, and more particularly, to a slim acoustic transducer including a diaphragm with a hole. For example, the hole may be substantially centered on a vertical axis of the diaphragm. For the purpose of description, the terms "loudspeaker," "loudspeaker device," and "loudspeaker system" may be used interchangeably in the specification.

[0009] For the purpose of description, the term "listening position" used herein generally refers to a position of a listener relative to a loudspeaker device.

[0010] For the purpose of description, a diaphragm is a membrane attached to a voice coil, which moves in a magnetic gap, vibrating the diaphragm, and producing sound.

[0011] FIG. 1 illustrates a cross-sectional view of a flat micro-speaker 100 according to a comparison example. The flat micro-speaker 100 includes a magnet 110, a top plate 120, a bottom plate (or frame) 125, a grill (or front cover) 130, a diaphragm 135, and a voice coil 140. A magnet 110 system portion of the flat micro-speaker 100 occupies a significant volume of space and limits the movement of the diaphragm 135 relative to a total built height 150 (acoustic module thickness, including an enclosure). A peak-to-peak displacement 155 of the diaphragm may be less than 40 % of the total thickness. A magnetic flux 160 is formed between the magnet 110 and the voice coil 140.

[0012] FIG. 2A illustrates a cross-sectional view of an ultra-thin transducer 200 according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 200 includes a lower (or bottom) magnet 210 (for example, ring-shaped, circular-shaped, cylindrical-shaped, or the like), a middle plate 220 (for example, ring-shaped, circular-shaped, cylindrical-shaped, or the like), an upper (or top) magnet 215 (for example, ring-shaped, circular-shaped, cylindrical-shaped, or the like), and a voice coil 240 (for example, ring-shaped, circular-shaped, elliptical-shaped, or the like). In some examples of the present disclosure, a magnet system may be arranged at least partially within an inner perimeter of the voice coil 240. The magnet system may have a column structure substantially centered on a vertical axis. The column structure may have a horizontal width that is equal to or less than an inner horizontal width of a structure shape of the voice coil 240. The column structure may include an upper magnet 215, a middle plate 220 arranged below the upper magnet 215, and a lower magnet 210 arranged below the middle plate 220. The magnet system minimizes a space from the movement of the diaphragm 225. In some examples of the present disclosure, each of the lower magnet 210 and the upper magnet 215 may include a rare earth magnetic material such as neodymium (Nd), neodymium iron boron (NdFeB), or samarium cobalt. In some embodiments of the present disclosure, the middle plate 220 may be made of low-carbon steel, soft magnetic steel, or a material similar thereto. In some embodiments of the present disclosure, the diaphragm 225 may include at least one of paper, polypropylene (PP), polyether ether ketone (PEEK), polycarbonate (PC), polyethylene terephthalate (PET), silk, glass fibers, carbon fibers, titanium, aluminum, an aluminum-magnesium alloy, nickel, or beryllium.

[0013] In some examples of the present disclosure, a top plate of the column structure may have a ring shape substantially centered on the vertical axis. The top plate may be the top magnet 215, which assists in directing at least some of an upper magnetic field substantially parallel to the vertical axis away from the voice coil 240. A bottom plate of the column structure may be substantially centered on the vertical axis. The bottom plate may include the lower magnet 210, which assists in directing at least some of a lower magnetic field substantially parallel to a horizontal axis adjacent to the vertical axis away from the voice coil 240. The lower magnet 210 may be, for example, a magnet ring. In some embodiments of the present disclosure, an enclosure including a lower frame 230 and an upper frame 235 (for example, low-carbon steel, soft magnetic steel, plastic, aluminum, or the like) may be twice a magnetic return path. In some embodiments of the present disclosure, a peak-to-peak displacement 270 may be greater than 50 % of a total thickness 275.

[0014] In one or more examples of the present disclosure, the diaphragm 225 may include or be connected to an outer suspension 250 (for example, a torus or the like). The transducer 200 may include a slot or vent 260 for radiating sound waves outside of the transducer 200 to a listening environment, and a slot or vent 265 for venting to an internal speaker volume. In some examples of the present disclosure, the top and bottom plates of the column structure may be a portion of a frame (that is, the lower frame 230 and the upper frame 235).

[0015] In some examples of the present disclosure, the diaphragm 225 may include a hole (or space, opening, or the like) 226. The hole 226 may be substantially centered on a vertical axis with respect to the diaphragm 225. The hole 226 may have a horizontal width. The voice coil 240 may be arranged at least partially in the hole 226. The voice coil 240 may have a shape (for example, a ring shape, a circular shape, an elliptical shape, or the like) that is substantially centered on the vertical axis of the diaphragm 225. The voice coil 240 may have an outer horizontal width and an inner horizontal width, where the outer horizontal width may be less than or equal to the horizontal width of the hole 226.

[0016] In some examples of the present disclosure, the magnet system produces a low-frequency output in an extremely thin form factor. The transducer 200 may optimize a stack-up topology for a maximum displacement. According to some examples of the present disclosure, the enclosure is a functional portion of the design of the transducer 200. In some examples of the present disclosure, the magnet system (or motor) of the transducer 200 is located in the center of the diaphragm 225 (not below the diaphragm as in designs according to the related art), providing a thin design with an increased range of movement. In some cases, there is no yoke / gap (direct magnetic return path), which increases a range of movement of the diaphragm 225 by using a fringe field of the magnet system. The transducer 200 also improves the symmetry of electromagnetic force and inductance during an in- / out-stroke. In some examples of the present disclosure, the transducer 200 provides a symmetric magnet layout, which improves sound quality by reducing distortion.

[0017] In some examples of the present disclosure, the transducer 200 may include a steel housing used for a magnetic return path on both sides of the column structure (no additional thickness required for the enclosure). The diaphragm 225 may be mounted at the center of the voice coil 240, and this improves the symmetry of the in- / out-stroke. In addition, this may also reduce or eliminate a former (bobbin) used in existing transducer designs. Further, a strategically arranged air vent of the transducer 200 may reduce vibration modes of the diaphragm 225, and this reduces distortion and a possibility for the voice coil 240 to rub against the magnet system structure. In some examples of the present disclosure, the transducer 200 may be implemented in devices and microelectronic equipment, such as mobile phones, camcorders, personal digital assistants (PDAs), digital cameras, notebook computers, televisions (TVs), digital versatile disks (DVDs), and the like.

[0018] FIG. 2B illustrates a cross-sectional view of an example ultra-thin transducer 200 showing an example magnetic flux 280, according to an example useful for understanding the present invention. In some examples of the present disclosure, the lower magnet 210 and the upper magnet 215 have opposite polarities to each other to increase the magnetic flux 280 at an edge of a pole plate. The voice coil 240 and the magnet system structure may be located in the center of the diaphragm 225. The magnet system may be centrally located in a driver, and a symmetric motor design may reduce even-order harmonic distortion.

[0019] FIG. 3 illustrates a cross-sectional view of an example slot-loaded ultra-thin transducer 200 showing upper slot 260 and lower slot 265 venting, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 200 discharges air straight to a listening environment from the upper slot 260 and discharges air straight to an internal speaker volume 320 from the lower slot 265.

[0020] FIG. 4 illustrates a cross-sectional view of the example slot-loaded ultra-thin transducer 200 showing asymmetric pressure (indicated by arrows 410 and 411) on the diaphragm 225 causing rocking motion, according to an example useful for understanding the present invention. Although slot loading of a transducer has advantages, slot loading of a thin transducer is likely to cause a vibration because the acoustic load on a diaphragm is asymmetric. This may cause distortion and also cause a voice coil to rub against a magnet structure. In some examples of the present disclosure, the transducer 200 provides a venting structure optimized to minimize the asymmetry of the acoustic load on the diaphragm 225, and this may mitigate issues related to slot loading of a planar transducer (for example, the flat micro-speaker 100 in FIG. 1) of the comparison example, which makes rocking likely to occur due to the asymmetric acoustic load on the diaphragm.

[0021] A transducer may exhibit symmetric behavior for an instroke and an outstroke. It is better that the electromagnetic force of the voice coil, coil inductance, and suspension stiffness are as symmetric as possible at remaining positions. Existing slim transducer designs sacrifice symmetry for a slim form factor. Some examples of the present disclosure may have perfect symmetry for the electromagnetic force and coil inductance.

[0022] FIGS. 5A to 5G respectively illustrate plan views of example slot-loaded ultra-thin transducers with various air-flow venting, according to an example useful for understanding the present invention.

[0023] FIG. 5A illustrates a plan view of the slot-loaded transducer 200 and the internal speaker volume 320 in a TV device 510, according to approaches of the related art. The transducer 200 includes an elliptical diaphragm 520. As shown by looking down at the transducer 200, the voice coil 240 surrounds a magnet system. The transducer 200 discharges air straight to a listening environment (for example, a room or the like) from the upper slot 260 (see FIGS. 2A and 2B) across the entire front of the transducer 200. The transducer 200 also discharges air for air flow to the internal speaker volume 320 from the lower slot 265 (FIGS. 2A and 2B).

[0024] FIG. 5B illustrates a plan view of the example slot-loaded ultra-thin transducer 200 with lateral exit slots 540 and 541 for air flow-venting, and the internal speaker volume 320 of the TV device 510, according to an example useful for understanding the present invention. In some examples of the present disclosure, improved air venting for the slot-loaded transducer 200 forces air venting through the lateral exit slots 540 and 541, and this improves the asymmetry of the diaphragm 225 (FIGS. 2A and 2B). In some examples of the present disclosure, the transducer 200 includes an optimum configuration of upper and lower walls (and exit slots 530 and 531 along with a slot venting to the internal speaker volume 320) that minimize the amount of rocking exhibited by the diaphragm 225.

[0025] FIG. 5C illustrates a plan view of the example slot-loaded ultra-slim transducer 200 with front-open air-flow venting, according to an example useful for understanding the present invention. FIG. 5D illustrates a plan view of the slot-loaded ultra-slim transducer 200 with air flow in the rear-center and sides to the internal speaker volume 320, according to an example useful for understanding the present invention. FIG. 5E illustrates a plan view of the example slot-loaded ultra-slim transducer 200 with front sides air-flow venting to a listening environment, according to an example useful for understanding the present invention. FIG. 5F illustrates a plan view of the example slot-loaded ultra-slim transducer 200 with rear-center air-flow venting to the internal speaker volume 320, according to an example useful for understanding the present invention. FIG. 5G illustrates a plan view of the example slot-loaded ultra-slim transducer 200 with back-sides air-flow venting to the internal speaker volume 320, according to an example useful for understanding the present invention.

[0026] FIG. 6 illustrates a graph 600 of the propensity for rocking motion 610 versus frequency 615 for the examples in FIGS. 5A to 5G. A curve 620 corresponds to the front-sides venting with the back-center venting; a curve 621 corresponds to the front-sides venting with the back-sides and center venting; a curve 622 corresponds to the front-sides venting with the back-center venting; a curve 623 corresponds to the front venting with the back-sides and center venting; a curve 624 corresponds to the front-sides venting with the back-sides venting; and a curve 625 corresponds to the front venting with the back-sides venting. As can be seen in the graph 600, the minimum propensity for rocking is achieved by the following configurations (less is better): front open (see FIG. 5A) with back-center open (and sides closed) (see FIG. 5F) (the case of 620), and front-sides open (see FIG. 5B) with back-center and sides open (see FIG. 5D) (the case of 621).

[0027] FIG. 7 illustrates a graph 700 of sound pressure level (SPL) 710 versus frequency 715 for the examples in FIGS. 5A to 5G, according to an example useful for understanding the present invention. A curve 720 corresponds to the front venting with the back-sides and center venting; a curve 721 corresponds to the front-sides venting with the back-sides and center venting; a curve 722 corresponds to the front venting with the back-center venting; a curve 723 corresponds to the front-sides venting with the back-center venting; a curve 724 corresponds to the front venting with the back-sides venting; and a curve 725 corresponds to the front-sides venting with the back-sides venting. As shown, the highest output occurs by the following configurations (more is better): front venting (see FIG. 5C) with back-center and sides venting (see FIG. 5D) (the case of 720), and front-sides venting (see FIG. 5B) with back-center and sides venting (see FIG. 5D) (the case of 721).

[0028] FIG. 8A illustrates a cross-sectional view of an example ultra-thin transducer 800 with a planar diaphragm 820, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 800 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the planar diaphragm 820, and a structure (or frame) 830. In some example embodiments of the present disclosure, the structure 830 may include low-carbon steel, soft magnetic steel, plastic, aluminum, or the like.

[0029] FIG. 8B illustrates a cross-sectional view of an example ultra-thin transducer 801 with a convex angled diaphragm 821, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 801 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the convex angled diaphragm 821, and the structure (or frame) 830.

[0030] FIG. 8C illustrates a cross-sectional view of an example ultra-thin transducer 802 with a concave angled diaphragm 822, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 802 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the concave angled diaphragm 821, and the structure (or frame) 830.

[0031] FIG. 8D illustrates a cross-sectional view of an example ultra-thin transducer 803 with the planar diaphragm 820 and an outer suspension (for example, a torus or the like) 840, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 803 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the planar diaphragm 820, the outer suspension 840, and the structure (or frame) 830.

[0032] FIG. 8E illustrates a cross-sectional view of an example ultra-thin transducer 804 with a structural diaphragm 850 and the outer suspension 840, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 804 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the structural diaphragm 850, the outer suspension 840, and the structure (or frame) 830. In some embodiments of the present disclosure, the structural diaphragm 850 may be made of structural foam or the like.

[0033] FIG. 8F illustrates a cross-sectional view of an example ultra-thin transducer 805 with the alternative-shaped voice coil 241, the structural diaphragm 850, and the outer suspension 840, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 805 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 241, the structural diaphragm 850, the outer suspension 840, and the structure (or frame) 830. In some examples of the present disclosure, the voice coil 240 has a different overall shape from the voice coil 240 (FIG. 2A) in that the shape of the voice coil 240 may be asymmetric or semi-asymmetric (for example, a reduction in dimension, angled, a change in thickness, a change in width / height, or the like).

[0034] FIG. 8G illustrates a cross-sectional view of an example ultra-thin transducer 806 with the other alternative-shaped voice coil 242, the structural diaphragm 850, and the outer suspension 840, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 806 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 241, the structural diaphragm 850, the outer suspension 840, and the structure (or frame) 830. In some examples of the present disclosure, the voice coil 242 has a different overall shape from the voice coil 240 (FIG. 2A) and the voice coil 241 (FIG. 8F) in that the shape of the voice coil 242 may be another asymmetric or semi-asymmetric shape (for example, a reduction in dimension, angled, a change in thickness, a change in width / height, or the like).

[0035] FIG. 8H illustrates a cross-sectional view of an example ultra-thin transducer 807 with the planar diaphragm 820 and an inner suspension 860, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 807 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the diaphragm 820, the inner suspension 860, and the structure (or frame) 830. In some examples of the present disclosure, the inner suspension 860 may be a foam suspension, a poly-foam suspension, or the like.

[0036] FIG. 8I illustrates a cross-sectional view of an example ultra-thin transducer 808, which has the planar diaphragm 820, a top plate 865, and a back plate 866 and is configured for slot radiation, according to some examples of the present disclosure. In some examples of the present disclosure, the transducer 808 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the diaphragm 820, the top plate 865, and the back plate 866. In some examples of the present disclosure, the slot or vent 260 radiates sound waves to a listening environment (for example, a room or the like), and the slot or vent 265 radiates sound waves internally to the speaker volume. In some examples of the present disclosure, each of the top plate 865 and the back plate 866 may be made of low-carbon steel, soft magnetic steel, or the like.

[0037] FIG. 8J illustrates a cross-sectional view of an example ultra-thin transducer 809 with the planar diaphragm 820 and a ferrofluid seal 841, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 809 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the diaphragm 820, the ferrofluid seal 841, and the structure (or frame) 830. The ferrofluid seal 841 uses a response of a magnetic field to an applied magnetic field of a magnet system of the transducer 809. A ferrofluid may function as a liquid O-ring. The ferrofluid seal 841 allows the transducer 809 to more efficiently function with an improved audio response and improved power handling. Audio ferrofluids are based on two types of carrier liquids, synthetic hydrocarbons and esters. Both oils exhibit extremely low volatility and thermal stability. Saturation magnetization (a maximum value of a magnetic moment per unit volume when all domains are aligned) is determined by properties of a suspended magnetic material and by the volumetric load of the material. Physical and chemical properties such as density and viscosity correspond closely to those of the carrier liquid.

[0038] FIG. 8K illustrates a cross-sectional view of an example ultra-thin transducer 810 with the planar diaphragm 820 and a grease seal 842, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 810 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the diaphragm 820, the grease seal 842, and the structure (or frame) 830. In some examples of the present disclosure, the grease seal 842 may be of a grease sealing compound type such as grease seal compounds including silicones.

[0039] FIG. 8L illustrates a cross-sectional view of another example ultra-thin transducer 811 with the planar diaphragm 820, a top plate 871, and a back plate 870, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 811 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the diaphragm 820, the top plate 871, the back plate 870, and the structure (or frame) 830. In some examples of the present disclosure, each of the top plate 871 and the back plate 870 may include low-carbon steel, soft carbon steel, or the like. In some examples of the present disclosure, the back plate 870 may be formed separately from or integrally with the structure (or frame) 830.

[0040] FIG. 8M illustrates a cross-sectional view of an example ultra-thin transducer 812 with the planar diaphragm 820, a perforated top plate 871 / 872 / 873, and a perforated back plate 870 / 874, according to some embodiments of the present disclosure. In some embodiments of the present disclosure, the transducer 812 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the diaphragm 820, the top plate 871 / 872 / 873 (see FIG. 13), and the back plate 870 / 874. In some embodiments of the present disclosure, each of the top plate 871 / 872 / 873 and the back plate 870 / 874 may be made of low-carbon steel, soft magnetic steel, or the like, portions of the top plate 873 and the back plate 874 are perforated to allow sound to radiate to a listening environment and a speaker enclosure, and other portions of the top plate 870 and the back plate 871 may be solid to maximize the flux near the voice coil 240. Although the ultra-thin transducer 812 is shown for direct radiation of sound (as opposed to slot radiation), some embodiments of the present disclosure may include a combination of slot radiation and direct radiation.

[0041] FIG. 8N illustrates a cross-sectional view of an example ultra-thin transducer 813, which has the planar diaphragm 820 and is configured for slot radiation, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 813 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the diaphragm 820, and a frame 880. In some examples of the present disclosure, the slot or vent 260 radiates sound waves to a listening environment (for example, a room or the like), and the slot or vent 265 radiates sound waves internally to a speaker volume. In some examples of the present disclosure, the frame 880 may be made of low-carbon steel, soft magnetic steel, plastic, aluminum, or the like.

[0042] FIG. 8O illustrates a cross-sectional view of an example ultra-thin transducer 814 with the planar diaphragm 820, the top plate 871, and the back plate 870, according to an example useful for understanding the present invention. In some examples of the present disclosure, the transducer 814 includes the lower magnet 210, the upper magnet 215, the middle plate 220, the voice coil 240, the diaphragm 820, the back plate 870, the top plate 871, and a structure (or frame) 811. The slot or vent 260 radiates sound waves to a listening environment (for example, a room or the like), and the slot or vent 265 radiates sound waves internally into a speaker volume. In some examples of the present disclosure, the frame 881 may be made of low-carbon steel, soft magnetic steel, plastic, aluminum, or the like. In some examples of the present disclosure, the back plate 870 and the top plate 871 may be formed separately from or integrally with the structure (or frame) 881.

[0043] FIG. 9A illustrates a cross-sectional view of an example transducer 900 according to the related art, which has a planar diaphragm and is configured for slot radiation. The transducer 900 includes a top portion having a width 920 of 1 mm, connection portions respectively having a width 930 of 2 mm and a width 940 of 6 mm, and a bottom portion having a width 950 of 1 mm. The total thickness of the transducer 900 is 10 mm, and the transducer 900 has a peak displacement of 2 mm.

[0044] FIG. 9A illustrates a cross-sectional view of an example ultra-thin transducer 950, which has a planar diaphragm and is configured for slot radiation, according to an example useful for understanding the present invention. The transducer 950 includes a voice coil 960 (for example, similar to the voice coil 240 in FIG. 2A), a frame 970, and an inner suspension 980 (for example, similar to the inner suspension 860 in FIG. 8H), the frame 970 including a top portion having a width 921 of 1 mm, connection portions respectively having a width 931 of 2 mm and a width 941 of 4 mm, and a bottom portion having a width 951 of 1 mm. The total thickness of the transducer 950 is 8 mm, and the transducer 950 has a peak displacement of 2 mm. The transducer 950 has a total thickness which is 20 % (that is, 2 mm) less than that of the transducer 900.

[0045] FIG. 10A illustrates a cross-sectional view of an example ultra-thin transducer 1000, which has a planar diaphragm and is configured for slot radiation, according to the related art. The transducer 1000 has a peak displacement 1020 of 1 mm and includes a top portion having and a width 1025 of 1 mm, a connection portion having a width 1030 of 2 mm, and a bottom portion 1010 having a width 1035 of 1 mm. The total thickness is 5 mm.

[0046] FIG. 10B illustrates a cross-sectional view of an example ultra-thin transducer 1050, which has a planar diaphragm and is configured for direct radiation, according to an example useful for understanding the present invention. The transducer 1050 includes a voice coil 1060 (for example, similar to the voice coil 240 in FIG. 2A) and an inner suspension 1080 (similar to the inner suspension 860 in FIG. 8H), together with a top portion having a width 1026 of 10 mm, a connection portion having a width 1031 of 2 mm, and a bottom portion having a width 1036 of 1 mm. The transducer 1050 has a total thickness of 4 mm and a peak displacement of 1 mm. The transducer 1050 has a total thickness which is 20 % (that is, 2 mm) less than that of the transducer 1000.

[0047] FIG. 11A illustrates a cross-sectional view of an example ultra-thin transducer 1100 with an inner surround 1120 to prevent short circuiting, according to an example useful for understanding the present invention. When a diaphragm moves forward, the diaphragm compresses air in front thereof while the medium is sparse at the opposite end. This causes a phase difference of 180°. At low frequencies, the diaphragm moves slowly such that air moves from one side to the other side and balances a difference in pressure. This produces a low-frequency air flow but no sound (acoustic short circuiting). In some examples of the present disclosure, the addition of the inner surround 1120 assists to prevent the occurrence of acoustic short circuiting. The inner surround 1120 may be made of foal, rubber, or the like.

[0048] FIG. 11B illustrates a cross-sectional view of an example ultra-thin transducer 1101 with a compressible material 1130 to prevent acoustic short circuiting, according to an example useful for understanding the present invention. In an example of the present disclosure, the compressible material 1130 may include compressible foam or a material similar thereto. In some examples of the present disclosure, the addition of the compressible material 1130 assists to prevent the occurrence of acoustic short circuiting.

[0049] FIG. 11C illustrates a cross-sectional view of an example ultra-thin transducer 1102 with the ferrofluid seal 841 (see FIG. 8J), according to an example useful for understanding the present invention. In some examples of the present disclosure, the addition of the ferrofluid seal 841 may assist to prevent the occurrence of acoustic short circuiting and may also reduce the propensity for rocking.

[0050] FIG. 12A illustrates a top perspective view of an example ultra-thin transducer 1200 with a top plate 1220, according to some examples of the present disclosure. The transducer 1220 includes a frame 1210 for supporting and mounting the transducer 1200. FIG. 12B illustrates a top perspective view of the example ultra-thin transducer 1200 of FIG. 12A with the top plate 1220 removed, according to an example useful for understanding the present invention. As shown, the transducer 1200 includes a magnet system including the upper magnet 215, the voice coil 240, and a diaphragm 1230 (for example, similar to the diaphragm 520 in FIG. 5A). FIG. 12C illustrates a cross-sectional view of the example ultra-thin transducer 1200 of FIGS. 12A and 12B, according to an example useful for understanding the present invention.

[0051] FIG. 13 illustrates a cross-sectional view of an example ultra-thin transducer 1300 with a perforated top plate 1310, according to some embodiments of the present disclosure. In some embodiments of the present disclosure, the transducer 1300 includes a magnet system (see FIG. 2A), the voice coil 240, and a diaphragm 1320. In some embodiments of the present disclosure, sound waves radiate out through perforations of the top plate 1310. The diaphragm 1320 has a circular or elliptical shape.

[0052] FIG. 14 illustrates a plan view of another example ultra-thin transducer 1400 with an elliptical diaphragm 1410, according to an example useful for understanding the present invention. It should be noted that various diaphragm shapes, such as different sized circular shapes, elliptical shapes, and the like, may be employed.

Claims

1. A speaker comprising a transducer (200, 800, 801, 802, 803, 804, 805, 806, 807, 808, 809, 810, 811, 812, 813, 814, 900, 1000, 1050, 1200, 1300), wherein the transducer comprises: a frame (830); a diaphragm (135, 225, 520, 820, 1230, 1320) fixed to the frame, the diaphragm comprising a hole (226) with a first horizontal width; a voice coil (140, 240, 241, 242, 960, 1060) affixed to the diaphragm and arranged at least partially in the hole; and a column structure (210, 215, 220) arranged at least partially in the voice coil, the column structure comprising: an upper magnet (215); a middle plate (220) arranged below the upper magnet; and a lower magnet (210) arranged below the middle plate, characterized by the speaker further comprising: a perforated top plate (871,872,873) placed on the upper magnet and on the upper side of the frame to allow sound to radiate to a listening environment; and a perforated back plate (870,874) placed on the lower magnet and on the lower side of the frame to allow sound to radiate to the listening environment.

2. The speaker of claim 1, wherein a shape of the voice coil is a ring shape with an outer horizontal width and an inner horizontal width, and the outer horizontal width is equal to or less than the first horizontal width of the hole.

3. The speaker of claim 1, wherein a shape of the voice coil is a ring shape with an outer horizontal width and an inner horizontal width, and the column structure has a horizontal width that is less than the inner horizontal width of the ring shape.

4. The speaker of claim 1, wherein the upper magnet is configured to apply an upper magnetic field to the voice coil; the lower magnet is configured to apply a lower magnetic field to the voice coil; and the middle plate is configured to guide at least one of the upper magnetic field or the lower magnetic field toward the voice coil.

5. The speaker of claim 1, wherein each of the upper magnet and the lower magnet comprises neodymium; and the middle plate comprises low-carbon steel.

6. The speaker of claim 1, further comprising a suspension attached to the diaphragm, wherein the suspension comprises at least one of an inner suspension or an outer suspension.

7. The speaker of claim 1, further comprising: a lubricant (841, 842) arranged between the voice coil and the column structure.

8. The speaker of claim 7, wherein the lubricant comprises at least one of a ferrofluid or grease.

9. The speaker of claim 1, wherein the diaphragm comprises structural foam.

10. The speaker of claim 1, wherein a vertical axis with respect to the diaphragm is at a center of the hole, a shape of the voice coil is a ring shape, and the ring shape is centered on the vertical axis.

11. The speaker of claim 10, wherein the column structure is centered on the vertical axis.

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