阅读说明：本技术 具有不均匀悬架和加强元件的扩音器 (Loudspeaker with non-uniform suspension and stiffening element ) 是由 B·帕兹埃斯 L·里斯博 C·廷加德 于 2020-04-08 设计创作，主要内容包括：一种扩音器,具有不均匀折环、膜和加固元件,阻止折环在操作期间使膜弯曲。不均匀折环沿着如果是圆形的扩音器的半径在围绕膜的整个周边上不具有相同的横截面,因为一些部分将向上指向而其他部分将向下指向。(A loudspeaker having a non-uniform edge, a membrane and a stiffening element, which prevents the edge from bending the membrane during operation. The uneven folds do not have the same cross section around the entire circumference of the membrane along the radius of the loudspeaker, if circular, because some parts will point upwards and other parts will point downwards.)

1. A loudspeaker comprising a membrane, a corrugated rim and a frame, wherein:

-the membrane has an outer edge,

-the edge of the rim is connected to the frame and to at least substantially all of the outer edge of the membrane,

-the edge has a first portion and a second portion, wherein:

-the first part is directed upwards, and

-the second portion is directed downwards,

the loudspeaker further comprises a stiffening element arranged at the outer edge of the membrane.

2. The loudspeaker of claim 1, wherein the first portion has a first radial cross-section and the second portion has a second radial cross-section, wherein the first radial cross-section and/or second radial cross-section has a U-shape or V-shape.

3. A loudspeaker as claimed in any preceding claim, wherein a portion of the corrugated rim between the first and second portions has an M-shaped or W-shaped cross-section.

4. A loudspeaker as claimed in any preceding claim, wherein the corrugated rim defines a repeating pattern along its central closed curve.

5. A loudspeaker as claimed in any one of claims 1 to 3, wherein a radial cross-section of a portion of the stiffening element has the shape of a closed curve.

6. A loudspeaker as claimed in claim 5, wherein the stiffening element is hollow.

7. The loudspeaker of claim 4, wherein the stiffening element is filled with a filler material.

8. A loudspeaker as claimed in claim 5, wherein a radial cross-section of a portion of the stiffening element has the shape of a polygon.

9. The loudspeaker of claim 8, wherein one side of the polygon is formed by the membrane.

10. A loudspeaker as claimed in claim 5, wherein a portion of the stiffening element is elliptical in radial cross-section.

11. A loudspeaker as claimed in any preceding claim, wherein the stiffening element forms a closed curve in a predetermined plane.

12. The loudspeaker of claim 11, wherein the combined membrane and stiffening element has a higher mass per unit area at the stiffening element than inside the closed curve when projected onto the plane.

13. A loudspeaker as claimed in any one of the preceding claims, wherein the diaphragm and stiffening element have a first mass per unit area in a plane perpendicular to the direction of movement of the membrane, and the diaphragm has a second mass per unit area in the plane at a location not at the stiffening element, wherein the first mass per unit area is higher than the second mass per unit area.

14. A loudspeaker as claimed in any one of claims 11 to 13, wherein the membrane and stiffening element in combination have a higher thickness at the stiffening element than inside the closed curve in a direction perpendicular to the plane.

15. A method of assembling a loudspeaker, the method comprising:

-providing a membrane having an outer edge,

-providing a corrugated rim having a first portion and a second portion, wherein:

-the first part is directed upwards, and

-the second portion is directed downwards,

-providing a stiffening element, and

-fixing the outer edge of the membrane to the fold and to the stiffening element.

Technical Field

The invention relates to a loudspeaker with an inhomogeneous suspension, such as a suspension that does not have the same cross section over the entire extent of the suspension, and which has stiffening or strengthening elements.

Background

Loudspeakers with uniform or non-uniform suspension can be seen in US6305491, US2011/164782, EP0556786, US2002/170773, Fostex UDR loudspeakers (https:// www.fostexinternational.com/docs/spreader _ components/pdf/fe208ez. pdf), US6889796, US2003/0231784, EP1659823, AES articles "diaphragm area and mass non-linearity" published by Knud Thorborg and Erling Sandermann Olsen 1995. Other uniform suspensions may be found in US7218748, EP1788839, US3997023, US3130811 and KEF white paper http: // www.kef.com/loads/files/THE _ REFERENCE/REF _ White _ Paper _ preview _ path _200514. pdf.

Non-uniform suspensions may be provided for a number of reasons, one of which is that uniform suspensions, such as half-roll, full-roll, multi-roll suspensions will produce with the membrane an effective membrane area that depends on the position of the membrane relative to the basin stand. The non-uniform suspension can be shaped to avoid such variations. However, it has been found that non-uniform suspensions can produce non-uniform forces acting on the edges of the membrane, causing the membrane to flex, thereby producing undesirable vibrations and sound.

Disclosure of Invention

It is an object of the present invention to provide a loudspeaker having an uneven surround (surround) but the membrane is not bent by the operation of the surround.

In a first aspect, the invention relates to a loudspeaker comprising a membrane, a corrugated rim and a frame, wherein:

the membrane has an outer edge,

the fold is connected to the frame and at least substantially all of the outer edge of the membrane,

the edge has a first portion and a second portion, wherein:

the first portion is directed upwards, such as by having a first radial cross-section, and

the second portion is directed downwards, such as by having a second radial cross-section, wherein the first radial cross-section and the second radial cross-section have different shapes,

the loudspeaker further comprises a stiffening element arranged at the outer edge of the membrane.

Herein, a loudspeaker is an element configured to generate and output sound. A typical loudspeaker comprises a membrane or diaphragm which is movable by a motor relative to a frame, a housing, a part of a motor, etc.

The membrane is typically a relatively rigid and typically planar or funnel-shaped element which is connected to a drive for moving the membrane. The membrane typically forms a perfect (sound) and/or at least substantially airtight seal between the chamber of the loudspeaker and the surroundings of the loudspeaker. Naturally, a plurality of membranes may be present in the loudspeaker and may be provided in the same chamber. There may also be a sound output port, such as a bass reflex port, if desired.

The film may be made of paper, cardboard, metal, polymer, or a combination thereof. The membrane may be symmetrical about an axis, such as axisymmetric. Typically, the membrane is circular, but oval shaped membranes can also be seen, as well as rectangular membranes with rounded corners.

The membrane may have a central axis defined as the intersection between two planes of symmetry. Typically, the intended direction of movement of the membrane is along the central axis. The central axis has an upward direction away from the motor and toward the membrane.

The membrane and the folds may have a radial cross-section defined as a cross-section through a plane coincident with the central axis. The radial cross-section of the corrugated rim may have a maximum value that is the point furthest upward along the central axis and a minimum value that is the point furthest downward along the central axis. The extreme value is one of a maximum value and a minimum value.

The membrane surface may be more or less flat or planar, or it may have more contours. The membrane may have ridges or the like, such as in a direction away from the central axis, for example, to increase the stiffness of the membrane. Other types of membranes have ridges formed as concentric rings at least at the outer portions, which function to vibrate only the innermost portion of the membrane at higher frequencies, but more and more parts of the membrane vibrate at lower and lower frequencies.

The frame is preferably a hard or rigid element which is not deformed to any significant extent by the action of the drive means moving the membrane to produce sound. Typically, the frame is made of metal. Typically, the frame is conical, having a base portion to which the driver is to be attached, and an outer portion having a shape corresponding to the shape of the corrugated rim, and to which the corrugated rim is to be attached. Between the base part and the outer part, struts may be formed connecting the base part and the outer part while leaving room for the membrane to move.

Typically, the frame will be connected at its outer portion to the loudspeaker cabinet to ensure that air cannot escape from the cabinet through the loudspeaker, at least to any significant extent.

The membrane has an outer edge. Typically the shape of the edge defines the shape of the membrane. Typically the membrane is circular.

A bellows is a flexible element that connects a generally stiffer membrane to a generally more rigid frame to allow the membrane to move relative to the frame while controlling the movement of the membrane relative to the frame and/or ensuring that air cannot bypass the membrane edges, which passage would short circuit the membrane, thereby destroying the sound producing characteristics.

The prior art tucks are usually half-rolls or full-rolls and have the same profile along the extent of the tuck, i.e. the tucks have a uniform profile. The conical edges and the folds are generally circular (projected on a plane perpendicular to the central axis). In this case, the uniform profile dog-leg will be axisymmetric, i.e., it may be described as a profile defined in a 2D plane rotated about a central axis.

Typically, the folds are made of rubber, impregnated cloth or closed foam, as such materials are light, flexible, and still impermeable to air to any significant extent.

The attachment of the folds to the membrane may be performed using, for example, glue (or co-moulding the folds to the membrane). Naturally, any type of fastening may be used.

In general, it is desirable for the folds to be attached or connected to the membrane at all outer portions and/or peripheries of the membrane in order to maintain good control of the membrane over all outer edges of the membrane to ensure that air cannot pass through the membrane/fold assembly.

Many of the bellows types result in the effective acoustically radiating area of the membrane/bellows assembly varying as a function of the position of the membrane relative to the frame. Typically, the effective area when the membrane enters the basin stand as much as possible is higher than when the membrane is as far away from the basin stand as possible (the two extreme parts of the operating interval of the membrane). The reason is that the shape of the folds differs at these two positions when, for example, a standard half roll is used.

There are hinge loops that reduce this problem. This type of hinge has a first portion and a second portion, wherein:

the first portion has a first radial cross section, and

-the second portion has a second radial cross section,

wherein the first radial cross-section and the second radial cross-section have different shapes.

Thus, this type of corrugated rim has a radial cross-section that differs at different locations along the rim, i.e. the contour of the rim is not uniform along its circumference. The cross-section may be that of a torus when viewed from the membrane towards the frame, such as from a portion of the outer edge of the membrane to the closest point of the frame. If the membrane is axisymmetric, then the frame is also axisymmetric, and thus the inner and outer portions of the folds are also axisymmetric. In this case, the first portion is a radial portion.

When the two portions have different radial cross-sections, this means that the shape of the edge around or along the edge is not the same. The two portions may have different curvilinear shapes, different highest or lowest points, such as when measured from the outer edge of the membrane. The height can be seen relative to a line from the edge of the membrane and the closest point of the frame-or from between the inner and outer edges of the fold.

For example, if the height of one portion at a selected distance from the edge of the membrane and/or the central axis of the membrane is more than 10% greater than the height of another portion at the same distance, then the portions are different.

The folds may be uneven for a number of reasons. One reason is that, as described above, the membranes have at least the same effective area when moving relative to the frame. In this case, the effective area of the membrane is generally the same, since the membrane is generally rigid enough not to bend to any significant extent. For a half roll, the relevant area of the edge is approximately the area of all portions of the edge within the apex of the radial cross-section of the edge. For half rolls, the maximum moves toward or away from the central axis according to the displacement of the film along the central axis, thereby changing the effective area.

Other folds have a non-uniform profile to prevent sound waves from exiting the fold.

It is an object of the present invention to reduce the bending of the membrane caused by uneven folding rings. Thus, the loudspeaker further comprises a stiffening element arranged at an outer edge of the membrane, such as at an interface between the membrane and the corrugated rim.

The stiffening element has the function of making the assembly of membrane and corrugated rim more rigid. It has been found that non-uniform folds, which do not have the same radial cross-section along their entire extent, cause the membrane to bend at the outer edge. This bending again leads to distortion of the radiated sound, which is clearly undesirable.

The function of the stiffening element is therefore to prevent the outer edge of the membrane from bending during its movement. The stiffening element should therefore be adapted to the expected forces of the used folding ring. The non-uniformity of the forces acting on the outer edge of the membrane is more or less severe depending on the shape of the folds.

When the membrane is bent, portions of the outer edge are drawn inwardly toward the center of the membrane, while other portions are pushed outwardly away from the central axis. The outer edge of which deviates from its shape in the rest position and without movement. For example, if the membrane is circular, the bend will change shape so it has multiple lobes. Two lobes will make the edge elliptical. Three lobes will give a more triangular shape. This phenomenon may occur at certain resonant frequencies.

The stiffening element may be as simple as a selected layer of material attached to the membrane and/or the crease, such as a portion of the crease adjacent or attached to an outer portion of the membrane. Obviously, additional layers of material may increase stiffness. However, further below, other shapes of the fold which further increase the stiffness are described, while maintaining the focus on the mass added by the stiffening element.

The stiffening element may have different stiffness in different directions, such as in a direction perpendicular to the extent of the stiffening element and/or towards the central axis of the membrane, and along the direction of movement of the membrane and/or the actuator. However, since the bending of the membrane is rather complex, it may be desirable for the stiffening element to have at least substantially the same stiffness in all directions, such as in all directions perpendicular to the direction of the centre line of the stiffening element or perpendicular to the outer edge of the membrane at a specific point.

The non-uniformity of the edge folds can be defined in many ways. In one instance, the radial cross-sections of the first and second portions each define a curve, such as an upper surface, a lower surface, or a center of the edge. The curve defined by the radial cross-section of the first portion may then be shorter than the curve defined by the radial cross-section of the second portion. When the curve between two poles is straighter, a shorter curve can be obtained. The curve may be derived relative to the straight line.

In this or another case, the curve defined by the radial cross-section of the first portion may have a narrower curvature than the curve defined by the radial cross-section of the second portion. The narrower bend may be a narrower peak or trough.

In one case, the radial cross-sections of the first and second portions have maxima (or minima) at different distances from the centre of the membrane. Again, this can be determined relative to the straight line described above.

In one case, the radial cross-section of the first portion and/or the second portion may be U-shaped or V-shaped. The portion between the first and second portions may then have an M-shaped or W-shaped radial cross-section.

Furthermore, the folds preferably define a repeating pattern along their central closed curve. The fold may then have portions with the same radial cross section as the first radial cross section and portions with the same radial cross section as the second radial cross section.

Obviously, the stiffening element may have any desired radial cross-section, such as a planar element, such as a sheet of material. One preferred shape is one in which a portion of the stiffening element has an L-shaped, T-shaped or I-shaped radial cross section. One of the planar sides of the stiffening element may then be attached to the membrane and/or the fold.

In another embodiment, the stiffening element has a portion with a radial cross section having a polygonal shape, such as a triangle, a rectangle (square, rhombus, parallelogram, trapezoid, kite, etc.), or the like. Likewise, one of the planar sides may then be attached to the membrane and/or the corrugated rim.

In practice, one of the substantially planar sides of the L-shape, I-shape, T-shape or polygon may be formed by the membrane and/or the fold so that the desired shape is not reached before attachment to the membrane/fold.

Alternatively, the stiffening element may have a portion with an elliptical, such as circular, radial cross-section.

Obviously, the shape, dimensions, material, etc. may be chosen on the basis of the bending forces exerted on the membrane and the maximum weight increase caused by the stiffening element.

Preferably, the stiffening element forms a closed curve in a predetermined plane, such as in the plane of the outer edge of the membrane. The closed curve has the advantage that the stiffening element is present all around the membrane. Preferably, the curve is at least 75% outside the radius/distance to the center. Obviously, the stiffening elements need not be positioned at the outer edges of the membrane to act to stiffen the outer portion of the membrane, as the membrane typically has its own stiffness. However, it is desirable that the stiffening element is positioned to perform its function at least in the outer quarter of the membrane, i.e. at a distance from the centre of the membrane of not less than 75% of the distance from the centre to the outer edge of the membrane. If the membrane is not circular, the stiffening elements will generally have the same shape and therefore be positioned at the same percentage of the total distance as measured perpendicularly from the central axis or along the surface of the membrane from the central axis.

In one case, the mass per unit area of the combined membrane and stiffening element, when projected onto a plane, is higher at the stiffening element than inside the closed curve. Although having a higher mass at the stiffening element may not be a goal per se, an increased mass generally means or results in a higher stiffness.

In one embodiment, the diaphragm and the stiffening element have a first mass per unit area in a plane perpendicular to the direction of movement of the membrane, and the diaphragm has a second mass per unit area in a plane at a location not at the stiffening element, wherein the first mass per unit area is higher than the second mass per unit area. Although in this projection a higher mass per unit area is not itself a target, a higher mass will generally give the desired higher stiffness.

In one embodiment, the combined membrane and stiffening element has a thickness in a direction perpendicular to the plane, which is higher at the stiffening element than inside the closed curve. While higher thicknesses are not themselves a goal, higher thicknesses generally give the desired higher stiffness.

As mentioned above, the stiffening element may be a separate element attached to the membrane, or the membrane may be manufactured with a built-in stiffening element, preferably at its outer portion. Such a build-in may be achieved by adding elements (elements) to the membrane material during the manufacturing process of the membrane, by providing a thicker, heavier, more rigid etc membrane material at its outer parts. In one case, the film may be molded, wherein the mold may be designed to produce a stiffening element as described above. The molding process may be a two-component molding, if desired. Alternatively, a portion of the membrane may be formed or shaped to constitute a thicker, more rigid portion.

A second aspect of the invention relates to a method of assembling a loudspeaker, the method comprising:

-providing a membrane having an outer edge,

-providing a corrugated rim having a first portion and a second portion, wherein:

the first portion is directed upwards, such as by having a first radial cross-section, and

the second portion is directed downwards, such as by having a second cross-section, wherein the first and second cross-sections are different in shape,

-providing a stiffening element, and

-fixing the outer edge of the membrane to the fold and the stiffening element.

Naturally, this aspect may be combined with the first aspect. The membrane, the fold, the first and second portions and the stiffening element may be as described above.

Drawings

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings, in which:

figure 1 shows a radial cross section of a loudspeaker according to the invention,

figure 2 shows a first embodiment of the stiffening element and its projected thickness,

figure 3 shows a second embodiment of the stiffening element,

figure 4 shows a third embodiment of the stiffening element,

figure 5 shows a first embodiment of the uneven crease,

figure 6 shows a second embodiment of the uneven crease,

figure 7 shows an alternative membrane with thicker or different material at the outer edge,

figures 8-13 show different types of stiffening elements.

Detailed Description

In fig. 1, a loudspeaker 1 is shown with a membrane 2, a motor 4, a frame 6 and a corrugated rim 8. The motor is configured to move the membrane up and down along axis a, and the tuck loops are configured to prevent air from bypassing the outer edge 12 of the membrane 2 and controlling the movement of the membrane 2. The fold 8 is connected at its outer periphery to the basin stand 6.

When the folds are not completely uniform, the movement of the membrane will cause the folds to bend, which again will cause the membrane to bend during movement. This bending results in distortion of the sound output, which is naturally undesirable. In fig. 1, the folding rings 8 are shown as being non-uniform, as can be seen from the different shapes of the left and right cross-sections.

The uneven folding rings can be seen in fig. 5 and 6. The dog collar in figure 5 can be seen in US6516077 and has a plurality of ridges 18 tangential to the outer edge 12. The remainder of the edge has the shape shown at 16. It is clear that different portions of the edge have different radial cross-sections and therefore have different effects on the outer edge 12.

The dog-ear in fig. 6 can be seen in EP0556786, where in the cross-section shown in fig. 1 a part of the dog-ear points downwards and a part points upwards, where the point of intersection between these parts looks like the point of intersection in fig. 6. It is clear that the part shown in fig. 6 affects the film differently from the half-rolled part, as seen from the leftmost and rightmost sides of the same figure.

These different effects on different parts of the outer edge will result in a bending of the membrane when moving.

In order to resist such bending, a stiffening element 10 is provided at the interface between the membrane and the fold. Fig. 2-4 show different shapes of such stiffening elements.

Bending of the membrane is a deformation that causes portions of the outer edge to be pulled toward the central axis of the membrane while other portions are pushed away from the central axis. There will be different bending modes, the first of which is that the outer edge becomes elliptical. The second mode is where the outer edge has three lobes and in the third mode it has four lobes. Obviously, when the membrane is bent, any number of lobes can be seen.

Fig. 2 shows a radial cross section of the outer edge 12 of the membrane 2 and the stiffening element 10, wherein the radial cross section of the stiffening element is rectangular. One side of the rectangle may be made of film material. The stiffening elements extend along the outer edge of the membrane, generally in a closed curve when projected onto a plane perpendicular to axis a. Obviously, the stiffening element will resist bending of the outer edge 12. The projected thickness of the assembly of membrane and stiffening element on a plane perpendicular to the central axis a is also shown.

The radial cross-section of the stiffening element may have any desired shape. In fig. 3, the shape is triangular. Likewise, the film material may form one of the sides. Advantageously, the shape shown may be a closed curve, such as a rectangle, polygon or ellipse.

In fig. 4, the radial cross-section of the stiffening element has a circular shape.

Naturally, any shape of stiffening element may be used. A polygon may be used and one or more sides may be formed by the membrane, if desired.

The stiffening element may be hollow or may be filled with a filler material, such as foam.

The stiffening element may be made of any type of material. Obviously, a higher stiffness is desired, but a weight as low as possible is desired. Thin aluminium may be used, such as having a thickness of 0.5 mm or less, such as 0.25 mm or less, such as 0.2 mm or less, such as 0.15 mm or less, other materials may be used, such as metals, alloys, polymers, paper, cardboard, plastics, composites, kevlar, etc.

The separate stiffening element may be replaced by an adaptation of the film material. Generally, the membrane is made of the same material with the same thickness, over the entire surface of the membrane, perpendicular to the extent of the membrane. However, the membrane may be made thicker at the outer edges to increase its stiffness.

Further alternatively, the membrane may be made of another material or additional material at the outer edge to increase the stiffness at the outer edge. This is shown in fig. 7. Thicker layers of material tend to be stiffer than thinner layers. Furthermore, the outermost portion of the membrane may be made of a more rigid material than the rest of the membrane to increase the stiffness of the membrane at the outer edge.

Fig. 8-13 show other types of stiffening elements, where fig. 8 shows the addition of a thin layer, e.g. paper, extending in the direction of movement, and in fig. 9 a layer is provided, e.g. paper, extending in a direction perpendicular to the direction of movement. Alternatively, the square of fig. 10 may be used, and also the circle of fig. 11, the 45-degree square (diamond shape) of fig. 12, or the triangle of fig. 13 having an angle of 90 degrees and the largest side extending in the moving direction of the film may be used.

Obviously, many different types, shapes, etc. of stiffening elements may be used. Other materials may also be used in order to better tailor the performance.