Non-planar diamond body for a loudspeaker dome

Abstract

A non-planar body (1) includes a dome body (2) having a vertex (3) and an outer periphery, the vertex (3) being located on a first plane (4), and the outer periphery being located on a second plane (6) substantially parallel to the first plane (4). A peripheral body (5) extends at least partially around the outer periphery of the dome body (2) and forms an angle (7) less than 180° with respect to a tangent (8) to the dome body (2) at the outer periphery of the dome body (2), the angle (7) being measured at the outer surface of the dome body (2). Either the dome body (2) or the peripheral body is formed of polycrystalline diamond.

Description

Technical Field

[0001] The present invention relates to the field of non-planar diamond bodies, in particular non-planar bodies made at least in part of polycrystalline diamond. Background Art

[0002] Diamonds have long been used in jewelry due to their long lifespan and aesthetic appeal. Diamond materials also have a range of desirable properties for a large number of different technical applications. For example, the high thermal conductivity of diamond makes it suitable for heat dissipation applications. The optical properties of diamond make it suitable for many optical applications. The hardness of diamond makes it excellent in grinding applications. The stiffness of diamond makes it suitable for applications such as speaker domes. Such speaker domes can form high-frequency tweeters with extremely high break frequencies beyond the human audio range to produce extremely high-quality sound within the human audio range. Non-planar diamond bodies can be used in applications including but not limited to speaker domes, microphone diaphragms, and optical elements.

[0003] WO2005 / 101900 discloses such a diamond speaker dome. As described in WO2005 / 101900, harmonics can extend below the fundamental break frequency, so it is desirable for the break frequency to be well removed from the end of the human audio range to ensure that sound reproduction is not impaired by the speaker dome bending at high frequencies. WO2005 / 101900 describes that a speaker dome with a high break frequency can be provided by a synthetic diamond speaker dome with a specific size of integral peripheral edge. No details of the specific manufacturing method for manufacturing such a speaker dome are stated in the literature.

[0004] In some applications, such as headphone speakers, where no separate tweeter is used, a single diamond speaker must handle a wider frequency range than that expected to be handled by a tweeter; this includes frequencies in the bass, midrange, and treble. GB2429367 discloses a diamond diaphragm having variable thickness, hardness, and damping characteristics to cover a wider frequency range. Summary of the Invention

[0005] For certain applications of non-planar diamond bodies, it is desirable to improve their performance.

[0006] According to a first aspect, there is provided a non-planar body comprising a dome body having a vertex and an outer periphery, the vertex being located in a first plane and the outer periphery being located in a second plane substantially parallel to the first plane. A peripheral body is formed to extend at least partially around the outer periphery of the dome body. When measured at the outer surface of the dome body, the peripheral body extends at an angle less than 180° with respect to a tangent to the dome body at the outer periphery of the dome body. Either the dome body or the peripheral body is formed of polycrystalline diamond.

[0007] Alternatively, the peripheral body extends substantially along the second plane.

[0008] Alternatively, the peripheral body extends towards the first plane.

[0009] Alternatively, both the dome body and the peripheral body are integrally formed from polycrystalline diamond.

[0010] Alternatively, the dome body includes a partially elliptical surface. Or, the dome body includes a partially spherical surface.

[0011] Alternatively, the peripheral body extends completely around the outer periphery of the dome body.

[0012] The peripheral body optionally includes any one of a partially annular surface, a frustoconical surface, and a substantially cylindrical surface. As a further alternative, the peripheral body includes a planar surface attached to the outer periphery of the dome body, and this planar surface is substantially located in the second plane.

[0013] When the non-planar body is projected onto a plane, the non-planar body optionally has a maximum linear dimension selected from any one of not less than 10 mm, not less than 20 mm, and not less than 30 mm.

[0014] Optionally, the maximum linear dimension is in a range selected from any one of 5 mm to 55 mm, 10 mm to 45 mm, 15 mm to 30 mm, or 25 mm to 35 mm.

[0015] Alternatively, the dome body has an average thickness selected from any one of not exceeding 500 μm, not exceeding 400 μm, not exceeding 300 μm, not exceeding 200 μm, not exceeding 100 μm, not exceeding 75 μm, not exceeding 50 μm, and not exceeding 25 μm.

[0016] Alternatively, the minimum thickness of the diamond in the non-planar body is greater than 20% of the maximum thickness of the non-planar body, greater than 30% of the maximum thickness of the non-planar body, greater than 40% of the maximum thickness of the non-planar body, or greater than 50% of the maximum thickness of the non-planar body.

[0017] The non-planar body optionally has a mass in a range selected from any one of 35 mg to 150 mg, 60 mg to 120 mg, 65 mg to 110 mg, 70 mg to 105 mg, or 70 mg to 100 mg.

[0018] Alternatively, the non-planar body further includes a second peripheral body extending from the outer periphery of the peripheral body.

[0019] The non-planar body is optionally circular in a planar view, and the ratio of the distance between the first plane and the second plane to the diameter of the non-planar body is selected from any one of 0.05 to 0.30, 0.08 to 0.2, and 0.10 to 0.15.

[0020] Optionally, the average thickness at the vertex of the dome body is greater than the average thickness at the outer periphery of the dome body.

[0021] According to a second aspect, there is provided a speaker dome including the non-planar body described in the first aspect above. Optionally, during use, the break-up frequency of the speaker dome is selected from any one of greater than 10 kHz, greater than 20 kHz, greater than 30 kHz, greater than 40 kHz, greater than 50 kHz, greater than 60 kHz, and greater than 70 kHz.

[0022] According to a third aspect, there is provided a method of manufacturing the non-planar body described in the first aspect above. The method includes providing a non-planar substrate in a reactor, growing a polycrystalline diamond film on the non-planar substrate, and removing the polycrystalline diamond film from the substrate to form the non-planar body.

[0023] The substrate is optionally formed of silicon, and the step of removing the polycrystalline diamond film from the substrate includes dissolving the silicon in an acid. Alternatively, the substrate is optionally formed of graphite, and the step of removing the polycrystalline diamond film from the substrate includes treating away the graphite from the polycrystalline diamond. Alternatively, the substrate is optionally formed of a refractory metal substrate that forms a carbide, and the step of removing the polycrystalline diamond film from the substrate includes cooling the refractory metal substrate that forms a carbide and the polycrystalline CVD (chemical vapor deposition) synthetic diamond material film at a controlled rate, whereby the polycrystalline CVD synthetic diamond material film delaminates from the metal carbide surface of the refractory metal substrate that forms a carbide during cooling.

[0024] The reactor is optionally selected from any one of a microwave plasma CVD reactor, a hot filament reactor, and a DC arc jet reactor.

[0025] Optionally, the non-planar substrate includes a convex dome shape or a concave dome shape.

[0026] Optionally, the method includes growing the dome body and the peripheral body integrally in the reactor. Alternatively, the dome body is grown in the reactor, and the method further includes attaching the peripheral body to the dome body to form the speaker dome. Alternatively, the peripheral body is grown in the reactor, and the method further includes attaching the dome body to the peripheral body to form the speaker dome. Description of the Drawings

[0027] Non-limiting embodiments will now be described by way of example and with reference to the accompanying drawings, in which:

[0028] Figure 1Schematically shows a side cross-sectional view of a first exemplary non-planar body;

[0029] Figure 2 Schematically shows a side cross-sectional view of a second exemplary non-planar body;

[0030] Figure 3 Schematically shows a side cross-sectional view of a third exemplary non-planar body;

[0031] Figure 4 Schematically shows a side cross-sectional view of a fourth exemplary non-planar body;

[0032] Figure 5 Schematically shows a side cross-sectional view of a fifth exemplary non-planar body;

[0033] Figure 6 Schematically shows a side cross-sectional view of a sixth exemplary non-planar body;

[0034] Figure 7 Schematically shows a side cross-sectional view of a seventh exemplary non-planar body;

[0035] Figure 8 Schematically shows a side cross-sectional view of an eighth exemplary non-planar body;

[0036] Figure 9 Schematically shows a side cross-sectional view of a ninth exemplary non-planar body;

[0037] Figure 10 Schematically shows a side cross-sectional view of a tenth exemplary non-planar body;

[0038] Figure 11 Schematically shows a side cross-sectional view of an eleventh exemplary non-planar body;

[0039] Figure 12 Schematically shows a side cross-sectional view of a twelfth exemplary non-planar body;

[0040] Figure 13 Schematically shows a side cross-sectional view of a thirteenth exemplary non-planar body;

[0041] Figure 14 Schematically shows a side cross-sectional view of a first exemplary substrate on which a non-planar body is grown;

[0042] Figure 15 Schematically shows a side cross-sectional view of a second exemplary substrate on which a non-planar body is grown;

[0043] Figure 16 Is a diamond thickness distribution diagram of a diamond non-planar body;

[0044] Figure 17Shows the breakup frequency models of three exemplary polycrystalline CVD diamond speaker domes; and

[0045] Figure 18 Is a flowchart showing exemplary steps for fabricating a non-planar body. DETAILED DESCRIPTION

[0046] The polycrystalline chemical vapor deposition (CVD) synthetic diamond portion of the non-planar body described herein can be grown using a variety of methods, including hot filament, microwave plasma, and DC arc jet reactors. Each of these methods has advantages. DC arc jet deposition systems tend to have highly localized growth rates, but suffer from electrode / nozzle erosion, high gas consumption, and relatively poor area coverage. Hot filament reactors can coat large areas and 3D shapes, but have limited film thickness and relatively poor diamond quality. In contrast, microwave plasma CVD diamond has been established as the primary method for producing high-quality bulk diamond. Unfortunately, due to the interaction of the microwave electric field and the non-planar substrate, the microwave plasma method has a limited ability to uniformly coat non-planar substrates. Even coating of simple 3D shapes (e.g., tool inserts or speaker dome mandrels) can be difficult due to the influence of electric field concentration at the outer corners or conversely weak electric field at the inner corners. This variation in the electric field adversely affects the quality and thickness uniformity of the diamond film. Materials that are thermally sensitive in terms of melting point or thermal shock are more challenging to uniformly coat in a microwave plasma reactor.

[0047] In view of the above, it is expected that the microwave plasma process will not be suitable for implementing the embodiments of the present invention. However, it has been found that careful control of the microwave plasma CVD equipment, careful treatment of the substrate surface, and careful control of the growth and cooling cycles make it possible to use the microwave plasma CVD process to carry out the present invention. Since this process produces higher quality diamond materials when compared with alternative growth methods, it is advantageous to use a microwave plasma CVD reactor to manufacture high-quality polycrystalline CVD synthetic diamond materials. For example, the CVD reactor can operate at a microwave frequency in the range of 800 MHz to 1000 MHz, and a pressure of at least 80 Torr, 100 Torr, 120 Torr, 140 Torr, 160 Torr, 180 Torr, 200 Torr, 230 Torr, 260 Torr or 300 Torr, and / or a microwave power of at least 2 kW, 5 kW, 10 kW, 15 kW, 20 kW, 25 kW or 30 kW. If high operating power and pressure are used for CVD diamond growth, cooling after growth can be achieved by reducing the power and pressure inside the CVD reactor to avoid thermally induced cracking of the polycrystalline CVD synthetic diamond non-planar body. For example, a controlled cooling rate can include reducing the growth temperature to at least 800 °C, 750 °C, 700 °C, 650 °C or 600 °C or 550 °C at a controlled rate of descent over a period of at least 10 minutes, 15 minutes or 20 minutes before extinguishing the plasma in the CVD reactor.

[0048] The process gas can include one or more of the following: a carbon-containing gas in the range of 1% to 10%, 1% to 7%, 2% to 5%, 2% to 4% or 2.5% to 3.5% of the total process gas flow; an inert gas, such as argon, in the range of 0.5% to 10%, 0.5% to 7%, 0.5% to 5%, 0.5% to 3% or 1.0% to 2.0% of the total process gas flow; and hydrogen, in the range of 85% to 98%, 90% to 98%, 93.0% to 97.5%, 94.0% to 96.5% or 95.0% to 96% of the total process gas flow. The process gas is directed towards the substrate through one or more gas inlet nozzles disposed opposite the substrate inside the CVD reactor.

[0049] To provide a non-planar shape of the non-planar body, diamond is deposited on a substrate providing a growth surface (convex or concave) that is predominantly dome-shaped. When projected onto a plane, the dome-shaped growth surface has a maximum linear dimension selected from any of not less than 10 mm, not less than 15 mm, not less than 20 mm, not less than 25 mm and not less than 30 mm.

[0050] As described above, it is known to provide a peripheral body for a loudspeaker dome that extends downward from the plane in which the apex of the dome lies. The inventors have surprisingly found that if the peripheral body is arranged to extend towards the plane in which the apex of the dome lies, improved loudspeaker dome performance can be achieved. There are many geometries that can be used to achieve this. Figures 1 to 13 Exemplary geometries are given in which the peripheral body extends towards the plane in which the apex lies. In Figures 1 to 13 the example given, it is assumed that the entire non-planar body is formed of polycrystalline diamond. However, as described below, the dome body or the peripheral body can be formed of different materials.

[0051] Figure 1 is a schematic side view of a first exemplary non-planar body 1. The non-planar body 1 has a dome body 2 that has an apex 3 located in a first plane 4. A peripheral body 5 intersects the dome body 2 at a point where it intersects the periphery of the dome body 2 in a second plane 6. The peripheral body 5 extends at an angle 7 less than 180° with respect to a tangent 8 to the dome body 2 about the outer periphery of the dome body 2, the angle being measured on the outer surface of the dome body 2.

[0052] The dome body 2 is elliptical and can have a circular plan view or a substantially elliptical plan view. This is suitable for Figures 1 to 13 all of the embodiments shown. In Figure 3 the example, the curved portion of the peripheral body 5 has a partially toroidal surface as it extends towards the first plane 4.

[0053] Figure 2 is a schematic side view of a second exemplary non-planar body 9. As in Figure 1 the embodiment of, the non-planar body 9 has a dome body 2 that has an apex 3 located in a first plane 4. A peripheral body 10 is located at the point where it intersects the periphery of the dome body 2 in a second plane 6 and extends along the second plane 6.

[0054] Figure 3 is a schematic side view of a third exemplary non-planar body 11. The non-planar body 11 has a dome body 2 that has an apex 3 located in a first plane 4. A peripheral body 12 is located at the point where it intersects the periphery of the dome body 2 in a second plane 6. The peripheral body 12 extends towards the first plane 4 (but note that it does not extend towards the apex 3). Note that before the peripheral body 12 begins to extend towards the first plane 4, a planar portion 13 of the peripheral body 12 forms an annulus around the periphery of the dome body 2.

[0055] The dome body 2 is elliptical and can have a circular plan view or a substantially elliptical plan view. This is applicable to Figures 1 to 13 all of the embodiments shown. In Figure 3In the example of [], the curved portion of the peripheral body 5 has a partially annular surface when extending towards the first plane 4.

[0056] When a non-planar body is used as a speaker dome, the voice coil is usually below the planar portion 13 of the peripheral body 12, or at the interface between the dome body 2 and the peripheral body 12.

[0057] Figure 4 is a schematic side view of a fourth exemplary non-planar body 14. As in Figure 3 In the embodiment of [], the non-planar body 14 has a dome body 2 with a vertex 3 located on the first plane 4. The peripheral body 15 is located at the point where it intersects the periphery of the dome body 2 on the second plane 6. The peripheral body 15 extends towards the first plane 4. In the fourth exemplary embodiment, the peripheral body 15 does not have a planar portion but starts to extend towards the first plane 4 at the point where it intersects the periphery of the dome body 2. When the peripheral body 15 extends towards the first plane 4, it has a partially annular surface.

[0058] Figure 5 is a schematic side view of a fifth exemplary non-planar body 16. The non-planar body 1 has a dome body 2 with a vertex 3 located on the first plane 4. The peripheral body 17 is located at the point where it intersects the periphery of the dome body 2 on the second plane 6. The peripheral body 17 extends towards the first plane 4. Before the peripheral body 17 starts to extend towards the first plane 4, the planar portion 18 of the peripheral body 17 forms an annulus around the periphery of the dome body 2. In Figure 5 In the example of [], the peripheral body 17 includes a frustoconical surface extending towards the first plane 4.

[0059] Figure 6 is a schematic side view of a sixth exemplary non-planar body 18. As in Figure 3 In the embodiment of [], the non-planar body 18 has a dome body 2 with a vertex 3 located on the first plane 4. The peripheral body 19 is located at the point where it intersects the periphery of the dome body 2 on the second plane 6. The peripheral body 19 extends towards the first plane 4. In the sixth exemplary embodiment, the peripheral body 19 does not have a planar portion but starts to extend towards the first plane 4 at the point where it intersects the periphery of the dome body 2. When the peripheral body 19 extends towards the first plane 4, it has a partially annular surface.

[0060] Figure 7 is a schematic side view of a seventh exemplary non-planar body 20. The non-planar body 20 has a dome body 2 with a vertex 3 located on the first plane 4. The peripheral body 21 is located at the point where it intersects the periphery of the dome body 2 on the second plane 6. The peripheral body 21 extends towards the first plane 4. Before the peripheral body 21 starts to extend towards the first plane 4, the planar portion 22 of the peripheral body 21 forms an annulus around the periphery of the dome body 2. In Figure 7In the example, the peripheral body 21 includes a partial annular surface extending towards the first plane 4. The difference between this annular surface and the partial annular surface 5 of the third exemplary non-planar body 1 is that in a side view, it is radially centered at a point above the second plane 6 relative to the first plane 4. In contrast, in the third exemplary embodiment, the partial annular surface is radially centered at a point on or below the second plane 6 relative to the first plane 4.

[0061] Figure 8 is a schematic side view of an eighth exemplary non-planar body 23. The non-planar body 23 has a dome body 2 with a vertex 3 located on the first plane 4. The peripheral body 24 is located at the point where it intersects the periphery of the dome body 2 on the second plane 6. In Figure 8 the example, the periphery of the dome body 2 is considered to be the inflection point where the curvature of the dome body changes to the curvature of the peripheral body 24. The peripheral body 24 extends towards the first plane 4. In Figure 8 the example, the peripheral body 24 includes a partial annular surface extending towards the first plane 4 in the same manner as the Figure 7 peripheral body 21 shown.

[0062] Figure 9 is a schematic side view of a ninth exemplary non-planar body 25. The non-planar body 25 has a dome body 2 with a vertex 3 located on the first plane 4. The peripheral body 26 is located at the point where it intersects the periphery of the dome body 2 on the second plane 6. The peripheral body 26 extends towards the first plane 4 (but note that it does not extend towards the vertex 3). Note that before the peripheral body 26 starts to extend towards the first plane 4, the planar portion 27 of the peripheral body 5 forms an annulus around the periphery of the dome body 2. In the ninth exemplary embodiment, the portion of the peripheral body 26 extending towards the first plane is substantially cylindrical, although it may deviate from the true cylindrical shape by a small angle to facilitate release from the substrate and improve deposition during the growth process.

[0063] Figure 10 is a schematic side view of a tenth exemplary non-planar body 28. As in Figure 3 the embodiment, the non-planar body 28 has a dome body 2 with a vertex 3 located on the first plane 4. The peripheral body 29 is located at the point where it intersects the periphery of the dome body 2 on the second plane 6. The peripheral body 29 extends towards the first plane 4. In the tenth exemplary embodiment, the peripheral body 29 does not have a planar portion but starts to extend towards the first plane 4 at the point where it intersects the periphery of the dome body 2. The peripheral body 29 is substantially cylindrical, although it may deviate from the true cylindrical shape by a small angle to facilitate release from the substrate and improve deposition during the growth process.

[0064] Figure 11is a schematic side view of an eleventh exemplary non-planar body 30. The non-planar body 30 has the same dome body 2 and peripheral body 10 as the third specific embodiment. A second peripheral body 31 extending from the peripheral body 10 is also provided. The second peripheral body 31 has a substantially cylindrical shape and extends towards or beyond the second plane 6.

[0065] The second peripheral body 31 extending towards the second plane 6 can also be provided on any one of the fourth to eighth exemplary embodiments.

[0066] Figure 12 is a schematic side view of a twelfth exemplary non-planar body 32. The non-planar body 32 has the same dome body 2 and peripheral body 10 as the first example. A second peripheral body 33 extending from the peripheral body 10 is also provided. The second peripheral body 33 has a substantially cylindrical shape and extends away from the second plane 6.

[0067] The second peripheral body 33 extending towards the second plane 6 can also be provided on any one of the second to sixth exemplary embodiments.

[0068] Figure 13 is a schematic side view of a thirteenth exemplary non-planar body 34. The non-planar body 34 has the same dome body 2 as the third exemplary embodiment. A cylinder 35 extending away from the first plane 4 along the outer periphery of the dome body is also provided, and a peripheral body 36 extending outward from the cylinder 35 along the direction towards the first plane 4.

[0069] The non-planar body can grow on a substrate or an inverted substrate having the same shape as the non-planar body (depending on how the non-planar body 1 is observed). Figure 14 A first exemplary substrate 37 is shown, on which the non-planar body 1 of the third exemplary embodiment is deposited. In this example, the substrate takes the same shape as the non-planar body 1.

[0070] Figure 15 A second exemplary substrate 38 is shown, on which the non-planar body 1 of the third exemplary embodiment is deposited. In this example, the substrate is inverted with respect to the shape of the non-planar body 1.

[0071] It should be understood that similar substrates can be used for Figures 1 to 13 any of the exemplary embodiments shown. When selecting the substrate design, those skilled in the art consider factors such as the ease of releasing the non-planar body from the substrate and the uniformity of diamond deposition on the substrate surface.

[0072] Those skilled in the art also know that the average grain size of diamond at the nucleation plane (i.e., the place where diamond starts to grow on the substrate) is usually larger than the average grain size of diamond on the opposite face. Since this can affect the performance of the resulting non-planar body, this factor can be considered by those skilled in the art when choosing the substrate design.

[0073] Those skilled in the art must also select a suitable substrate material. Materials such as refractory metals that form carbides, silicon, graphite, polycrystalline diamond, silicon carbide, and silicon carbide / diamond composites can be used. US5556464 describes forming a speaker dome by chemically vapor depositing a diamond material on a raised curved substrate to form a synthetic diamond film thereon, and then separating the synthetic diamond film from the substrate to produce the diamond speaker dome. The synthetic diamond material is deposited on a raised curved silicon substrate, and the separation of the synthetic diamond film from the substrate is achieved by dissolving the silicon substrate in an acid to produce the diamond speaker dome.

[0074] As described in WO2013 / 178535, an alternative method is to use a refractory carbide-forming metal as the substrate. In this case, careful control of the surface roughness of the substrate is described. Polycrystalline CVD diamond is deposited on the substrate, and the mismatch in the coefficient of thermal expansion between the diamond and the substrate allows the diamond to be released from the substrate in a controlled manner upon cooling. This type of process is also suitable for forming the non-planar bodies described herein, but it should be understood that complex formed-factor shapes may cause the diamond to bond to the substrate and increase the risk of cracking when the diamond is released from the substrate.

[0075] A set of exemplary non-planar bodies are made to have Figure 12 the geometric shape shown, which has a second peripheral body 33 extending towards the first plane 4. They are grown on a prepared silicon substrate having the geometric shape as Figure 15 shown. Each one is manufactured in a microwave plasma CVD reactor using methane as the carbon source. Non-planar bodies with a maximum film thickness of up to 100 microns are grown, and their total mass varies between 40 mg and 140 mg. A low mass is an ideal property for applications such as speaker domes because it allows for responsive movement.

[0076] The shape of the substrate affects the electric field in the reactor, thereby affecting the plasma during the diamond growth process. The deposition rate of diamond is higher in some regions than in others. Figure 16 is the average diamond thickness distribution diagram of the diamond non-planar body. The percentage of the substrate height relative to the maximum substrate height is shown as a solid black line, and the percentage of the diamond thickness relative to the maximum film thickness is shown as a dashed black line.

[0077] It can be seen that the maximum diamond thickness occurs at the highest point on the side of the substrate. The minimum thickness is at the vertex of the non-planar body. Towards the edge of the non-planar body, the diamond also becomes thicker. This thickness distribution may be beneficial because the non-planar body has the minimum mass at the vertex of the dome body 2 and is strengthened by the additional mass at the edge of the dome body 2. This is particularly advantageous in speaker dome applications, where the mass at the vertex should be as low as possible to reduce the inertia when the speaker dome moves, but the mass at the perimeter of the dome body should be increased to strengthen the speaker dome.

[0078] The dome body typically has an average thickness selected from any one of not more than 500 μm, not more than 400 μm, not more than 300 μm, not more than 200 μm, not more than 100 μm, not more than 75 μm, and not more than 50 μm.

[0079] The thickness of the diamond in the non-planar body is such that the minimum thickness of the non-planar body is greater than 20% of the maximum thickness of the non-planar body, greater than 30% of the maximum thickness of the non-planar body, greater than 40% of the maximum thickness of the non-planar body, or greater than 50% of the maximum thickness of the non-planar body.

[0080] The non-planar body typically has a mass selected from any one of 35 mg to 150 mg, 60 mg to 120 mg, 65 mg to 110 mg, 70 mg to 105 mg, or 70 mg to 100 mg.

[0081] To study the effect of the peripheral body 5 extending towards the first plane 4, a finite element analysis (FEA) was performed on three different geometries of the speaker dome:

[0082] A: The speaker dome has the Figure 12 geometry and is formed by the dome body 2 and a peripheral body integrally formed of polycrystalline CVD diamond.

[0083] B: A speaker dome without a peripheral body; and

[0084] C: A speaker dome with a peripheral body extending away from the first plane 4, as described in WO2005 / 101900.

[0085] The FEA was performed using Abaqus linear perturbation frequency analysis to identify the eigenmodes or natural vibrations of the structure. Example A gave a break-up frequency of 45.0 kHz, Example B gave a break-up frequency of 38.8 kHz, and Example C had a break-up frequency of 41.7 kHz. It can be seen from Figure 17 that Example A also had different break-up modes. The increase in the break-up frequency may be due to the peripheral body restricting the vibration.

[0086] The above example describes a non-planar body formed entirely of polycrystalline diamond. However, it is possible that only the dome body 2 or the peripheral body 5 is formed of polycrystalline diamond while the other part is formed of a different material. The dome body 2 should be formed of a material with high stiffness having a Young's modulus greater than 50 GPa, preferably greater than 100 GPa, 200 GPa, 300 GPa, 500 GPa or 1000 GPa. The dome body 2 should also preferably be made of a low-density material. As described above, polycrystalline diamond is suitable as the material for the dome body 2. The common Young's modulus and density values of polycrystalline diamond and other materials with high Young's modulus are shown in Table 1 below. It can be seen that polycrystalline diamond has a significantly higher Young's modulus and a density comparable to other materials, and thus provides a harder speaker dome with a higher break-up frequency compared to speaker domes made of other materials.

[0087] Table 1: Selected properties of materials:

[0088] Material Young's modulus GPa <![CDATA[Density g / cm 3 > Mg 45 1.74 Al 70 2.70 Au 79 19.3 Be 287 1.85 Sapphire 345 3.98 Polycrystalline diamond 1143 3.51

[0089] To provide another material with high Young's modulus, the dome body 2 or the peripheral body 10 can be formed of the materials in Table 1, or of a dense or partially dense metal or a metal alloy composite material embedded with superhard particles or grit. In this case, the superhard particles or grit can be diamond or cubic boron nitride. The dome body 2 can be made of polycrystalline diamond and the peripheral body 10 can be made of another material as described above. Alternatively, the dome body 2 can be made of the above-mentioned another material and the peripheral body 10 can be made of polycrystalline diamond material. The peripheral body 10 and the dome body 2 can be joined together using any suitable technique, such as using an adhesive.

[0090] It should also be noted that it may be advantageous to provide a coating on the non-planar body, such as those described in WO2012 / 110357.

[0091] Now turning to Figure 18 , a flowchart showing exemplary steps of manufacturing a non-planar body is shown. The following numbers correspond to Figure 18 the numbers shown:

[0092] S1. A non-planar substrate is provided. Any suitable substrate can be used. For example, it is known to grow diamond on a silicon substrate, a graphite substrate, a silicon carbide body or a refractory metal forming a carbide (e.g., tungsten, molybdenum, niobium, tantalum, titanium and their alloys) substrate. Note that the non-planar substrate can be used as the substrate for forming the entire non-planar body, where the dome body and the peripheral body are integrally formed, or can be used to form only one of the dome body or the peripheral body. In the case where the dome body is formed on the substrate, the substrate can include a convex or concave dome body on which diamond is grown.

[0093] S2. The substrate is placed in a reactor, and diamond is grown on the substrate. Suitable reactors include microwave plasma CVD reactors, hot filament reactors, and DC arc jet reactors.

[0094] S3. Once the diamond has grown to a suitable thickness, the diamond is removed from the substrate. In the case where the substrate is formed of silicon, the step of removing the polycrystalline diamond film from the substrate may include dissolving the silicon in an acid. In the case where the substrate is formed of graphite, the step of removing the polycrystalline diamond film from the substrate may include removing the graphite from the polycrystalline diamond. In the case where the substrate is formed of a refractory metal substrate that forms a carbide, the step of removing the polycrystalline diamond film from the substrate may include cooling the refractory metal substrate that forms a carbide and the polycrystalline CVD synthetic diamond material film at a controlled rate, whereby the polycrystalline CVD synthetic diamond material film delaminates from the metal carbide surface of the refractory metal substrate that forms a carbide during cooling.

[0095] In the case where the polycrystalline diamond does not form the entire non-planar body, the method further includes attaching another part to the polycrystalline diamond to form a non-planar body. For example, when a dome body is grown in a reactor, the method further includes attaching a peripheral body to the dome body to form a non-planar body. In the case where a peripheral body is grown in a reactor, the method further includes attaching a dome body to the peripheral body to form a non-planar body.

[0096] Although the present invention has been specifically shown and described with reference to preferred embodiments, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the present invention as defined by the appended claims. For example, a microwave plasma CVD reactor is used to manufacture the above-described exemplary embodiments, but those skilled in the art will understand that various techniques may be used to manufacture non-planar bodies, including hot filaments and DC arc jet reactors.

Claims

1. A non-planar diamond body for a speaker dome, comprising: A dome body having a vertex and an outer periphery, the vertex being located on a first plane and the outer periphery being located on a second plane substantially parallel to the first plane; A peripheral body that at least partially extends around the outer periphery of the dome body, wherein when measured at the outer surface of the dome body, the peripheral body extends at an angle less than 180° with respect to the tangent to the dome body at the outer periphery of the dome body, and wherein the peripheral body extends towards the first plane; Wherein the dome body and the peripheral body are integrally formed of polycrystalline diamond; and Wherein the non-planar diamond body is circular in a planar view, and the ratio of the distance between the first plane and the second plane to the diameter of the non-planar diamond body is in the range of 0.05 to 0.

30.

2. The non-planar diamond body according to claim 1, wherein the dome body comprises a partially elliptical surface.

3. The non-planar diamond body according to claim 1, wherein the dome body comprises a partially spherical surface.

4. The non-planar diamond body according to claim 1, wherein the peripheral body completely extends around the outer periphery of the dome body.

5. The non-planar diamond body according to claim 1, wherein the peripheral body comprises any one of a partially annular surface, a frustoconical surface, and a substantially cylindrical surface.

6. The non-planar diamond body according to claim 1, wherein, The non-planar diamond body has a maximum linear dimension selected from any one of not less than 10 mm, not less than 20 mm, and not less than 30 mm when projected onto a plane.

7. The non-planar diamond body according to claim 1, wherein the dome body has an average thickness selected from any one of not more than 500 , not more than 400 , not more than 300 , not more than 200 , not more than 100 , not more than 75 , not more than 50 , and not more than 25 .

8. The non-planar diamond body according to claim 1, wherein the minimum thickness of the diamond in the non-planar diamond body is greater than 20%, greater than 30%, greater than 40%, or greater than 50% of the maximum thickness of the non-planar diamond body.

9. The non-planar diamond body according to claim 1, further comprising a second peripheral body extending from the outer periphery of the peripheral body.

10. The non-planar diamond body according to claim 1, wherein, The ratio of the distance between the first plane and the second plane to the diameter of the non-planar diamond body is selected from any one of 0.08 to 0.2 and 0.10 to 0.

15.

11. The non-planar diamond body according to claim 1, wherein the average thickness at the vertex of the dome body is greater than the average thickness at the outer periphery of the dome body.

12. A speaker dome, the speaker dome comprising the non-planar diamond body according to claim 1.

13. A method of manufacturing the non-planar diamond body according to claim 1, the method comprising: Providing a non-planar substrate; Growing a polycrystalline diamond film on the non-planar substrate in a reactor; Removing the polycrystalline diamond film from the non-planar substrate to form the non-planar diamond body.

14. The method according to claim 13, wherein the non-planar substrate is formed of silicon, and the step of removing the polycrystalline diamond film from the non-planar substrate comprises dissolving the silicon in an acid.

15. The method according to claim 13, wherein the non-planar substrate is formed of graphite and the step of removing the polycrystalline diamond film from the non-planar substrate comprises treating away the graphite from the polycrystalline diamond.

16. The method according to claim 13, wherein the non-planar substrate is formed of a carbide-forming refractory metal substrate, and the step of removing the polycrystalline diamond film from the non-planar substrate comprises cooling the carbide-forming refractory metal substrate and the polycrystalline CVD synthetic diamond material film at a controlled rate, whereby the polycrystalline CVD synthetic diamond material film delaminates from the metal carbide surface of the carbide-forming refractory metal substrate during cooling.

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