A flat earphone with an air guiding structure

Abstract

The present invention provides a planar headphone with an air guiding structure, comprising an electromagnetic transducer; the electromagnetic transducer includes: a mounting member, an annular magnet, a diaphragm and a coil; wherein, an acoustic opening is provided at the geometric center of the annular magnet; the diaphragm is mounted on the mounting member and includes a radiation surface facing the acoustic opening; the coil is located on the diaphragm and within the magnetic field of the annular magnet; the diaphragm at least has a central region without a coil arrangement and axially aligned with the acoustic opening, and when the electromagnetic transducer is driven by an audio signal, the central region generates sound that propagates into the surrounding environment through the acoustic opening; the surface of the annular magnet close to the diaphragm and the inner side surface close to the central axis are connected by a transition surface, and at least the transition surface is provided with a plurality of air guiding structures protruding from the annular magnet towards the diaphragm; it can improve the sensitivity and reduce the distortion rate.

Description

Technical Field

[0001] The present invention relates to the field of audio output devices, and more particularly to a planar headphone having an air guiding structure Background Art

[0002] A planar electromagnetic transducer composed of a combination of a permanent magnet assembly and a diaphragm is a known technology in planar headphones. This type of electromagnetic transducer generally includes a permanent magnet assembly, a diaphragm disposed opposite to the permanent magnet assembly, and a support member for fixing the diaphragm to the permanent magnet assembly in the peripheral region of the permanent magnet assembly

[0003] The permanent magnet assembly used in this type of conventional electromagnetic transducer has a plurality of elongated permanent magnets, each permanent magnet having two opposite magnetic poles on the surfaces on both sides thereof, and the magnets are arranged in a parallel relationship such that the N poles and S poles are alternately and firmly joined together by non-magnetic members. The diaphragm is a thin resin film, and a coil in an "S" shape or a "hui" shape pattern is formed on its surface. The diaphragm is combined with the permanent magnet assembly such that the straight portion of the coil pattern is exactly located in the central region between the parallelly arranged elongated permanent magnets. In practical applications, the diaphragm is fixed to the permanent magnet assembly in the peripheral region of the permanent magnet assembly by one or more spacers

[0004] Magnetic field lines extend between the magnetic poles of two adjacent elongated permanent magnets, and a magnetic field is generated in a manner transverse to the linear portion of the conductor pattern of the diaphragm. When the coil of the diaphragm is energized, an electromagnetic force is generated according to Fleming's left hand rule, and the diaphragm is displaced in its thickness direction. According to this rule, vibrations corresponding to the drive current to the coil are generated to produce sound waves. The sound waves pass through the elongated permanent magnets and thus radiate outwards

[0005] The corresponding coils on the diaphragm in conventional planar headphones usually extend at the center of the diaphragm. This arrangement limits the movement of the diaphragm in the vertical direction of its surface, which forces a trade-off between the acoustic range and the driver efficiency. The gap between the permanent magnet and the diaphragm can be increased to allow the diaphragm to move more in the vertical direction of its surface and produce lower frequency sounds. However, widening the gap also separates the permanent magnet and the coil to a greater extent, which may reduce the overall efficiency of the planar electromagnetic transducer. In addition, the permanent magnet blocks the propagation path of the sound generated by the diaphragm, which may deteriorate the sound quality. Even if through holes are arranged between the permanent magnets, the aperture of the through holes is small, which is extremely likely to cause standing waves to form in the openings, thereby further distorting the sound Summary of the Invention

[0006] In view of the above disadvantages in the prior art, the present invention provides a planar headphone having an air guiding structure. The planar headphone includes an electromagnetic transducer; the electromagnetic transducer includes:

[0007] One or more mountings having a mounting profile extending around a central axis, wherein the mounting profile does not move along the central axis;

[0008] An annular magnet extending around the central axis to define an acoustic opening radially inward from the mounting profile;

[0009] A diaphragm mounted on the one or more mountings and including a radiating surface facing the acoustic opening; and

[0010] One or more coils located on the diaphragm and within the magnetic field of the annular magnet;

[0011] The diaphragm has at least a central region without a coil arrangement and axially aligned with the acoustic opening, which generates sound propagating into the surrounding environment through the acoustic opening when the electromagnetic transducer is driven by an audio signal;

[0012] The surface of the annular magnet close to the diaphragm is connected to the inner side close to the central axis by a transition surface, and at least the transition surface is provided with a plurality of air guiding structures protruding from the annular magnet and facing the diaphragm.

[0013] Preferably, there are two sets of the annular magnets, respectively arranged on both sides of the plane where the diaphragm is located; the coils are within the magnetic gap between the two sets of the annular magnets.

[0014] Preferably, the width or diameter of the acoustic opening is 2 - 6 times the annular width of the annular magnet.

[0015] Preferably, the transition surface is arc-shaped in the radial cross-section of the annular magnet.

[0016] Preferably, the arc-shaped curve of the transition surface in the radial cross-section of the annular magnet is obtained based on a Bessel nth-order polynomial.

[0017] Preferably, the arc-shaped curve of the transition surface in the radial cross-section of the annular magnet is obtained based on a Bessel fourth-order polynomial with five control points.

[0018] Preferably, the positions of the control points are obtained by the following method: taking the positions of the control points as inputs and the sensitivity and distortion rate of the whole electromagnetic transducer as outputs, establishing a neural network model; inputting a measured data set into the neural network model for training, calculating the error between the predicted value and the corresponding actual value using the adaptive moment estimation algorithm, modifying the weights and bias coefficients of the neural network model layer by layer according to the error, obtaining a trained neural network model; performing optimization calculations with the sensitivity and distortion rate as the objectives based on the neural network model, and selecting the positions of the control points corresponding to the optimal solution.

[0019] Preferably, the neural network model includes an input layer, six hidden layers, and an output layer; the input layer is connected to the output layer through six hidden layers in sequence, and the six hidden layers are connected in sequence. The input layer mainly consists of five neurons, each hidden layer mainly consists of ten neurons, and the output layer mainly consists of two neurons. The output layer outputs the sensitivity and distortion rate of the electromagnetic transducer output respectively.

[0020] Preferably, the weights and bias coefficients of the neural network model are modified layer by layer according to the error. Specifically, the error is recorded as the first error. After taking the partial derivative of the first error and multiplying it by the first error coefficient, it acts on the hidden layer connected to the output layer to modify the original weights and original biases of the hidden layer connected to the output layer, and obtain the new weights and new biases of the current hidden layer; then, calculate the error between the original biases and original weights and the new weights and new biases of the current hidden layer and record it as the second error. After taking the partial derivative of the second error and multiplying it by the second error coefficient, it acts on the previous hidden layer to modify the original weights and original biases of the previous hidden layer, and obtain the new weights and new biases of the previous hidden layer; until all hidden layers are modified.

[0021] Preferably, the optimization calculation adopts a genetic algorithm, a simulated annealing algorithm, or a particle swarm algorithm.

[0022] Preferably, one or more of the mounting members include a first compliant pad and a second compliant pad, and the diaphragm is mounted between the first compliant pad and the second compliant pad.

[0023] Preferably, the air guiding structure is a rib, and the ribs are arranged at equal intervals in the circumferential direction on the outer surface of the annular magnet and are centrosymmetrically distributed.

[0024] Preferably, the rib is linear or arc-shaped.

[0025] Preferably, the length direction of the rib is the radial direction of the annular magnet.

[0026] Preferably, the length direction of the rib forms an angle greater than 0° and less than 90° with the radial direction of the annular magnet.

[0027] The annular magnet extends around the central axis to define an acoustic opening radially inward from the mounting profile, allowing the vertical displacement of the radiation surface facing the acoustic opening at the center of the diaphragm to be significantly higher than that of the magnet surface facing the diaphragm 103, increasing the air volume displacement and sound generation, improving the sensitivity, and reducing the energy consumption; by providing a transition surface at the acoustic opening, the acoustic wave reflection at the acoustic opening can be reduced, which not only provides a larger displacement space for the diaphragm but also reduces the distortion rate of the generated sound; the air guiding structure on the outer surface of the annular magnet guides the air between the diaphragm and the annular magnet to flow quickly and evenly, and can prevent the diaphragm from coming into large-area contact with the annular magnet, also achieving the technical effects of improving the sensitivity and reducing the distortion rate. Description of the Drawings

[0028] Figure 1 Schematic diagram of the electromagnetic transducer of a planar headphone with an air guiding structure according to an embodiment of the present invention;

[0029] Figure 2 For the present invention Figure 1 Partial schematic diagram of the inner side of the annular magnet circled in the electromagnetic transducer shown;

[0030] Figure 3 For the present invention Figure 2 Schematic diagram of constructing the shape of the transition surface shown;

[0031] Figure 4 For the present invention Figure 2 Schematic diagram of the rib distribution in the annular magnet shown.

[0032] Among them, electromagnetic transducer - 100, mounting member - 101, annular magnet - 102, diaphragm - 103, coil - 104, central axis - 105, acoustic opening - 106, magnetic field line - 107, transition surface - 108, air guiding structure - 109, control point - 110, magnetic induction line - 111. Detailed Description of the Invention

[0033] In order to address the problems of poor sensitivity and high distortion rate of existing planar headphones, the planar headphone with an air guiding structure provided by the present invention is achieved through the following technical solutions:

[0034] Embodiment 1:

[0035] This embodiment provides a planar headphone with an air guiding structure. Please refer to Figure 1-2 , which includes an electromagnetic transducer 100; the electromagnetic transducer 100 includes:

[0036] One or more mountings 101 having a mounting profile extending around a central axis 105, wherein the mounting profile does not move along the central axis 105;

[0037] An annular magnet 102 extending around the central axis 105 to define an acoustic opening 106 radially inward from the mounting profile;

[0038] A diaphragm 103 mounted on the one or more mountings 101 and including a radiating surface facing the acoustic opening 106; and

[0039] One or more coils 104 located on the diaphragm 103 and within the magnetic field of the annular magnet 102;

[0040] The diaphragm 103 has a central region arranged without the coil 104 and axially aligned with the acoustic opening 106. When the electromagnetic transducer 100 is driven by an audio signal, the central region generates sound that propagates through the acoustic opening 106 into the surrounding environment;

[0041] The surface of the annular magnet 102 close to the diaphragm 103 and the inner side close to the central axis 105 are connected by a transition surface 108, and at least the transition surface 108 is provided with a plurality of air guiding structures 109 protruding from the annular magnet 102 and facing the diaphragm 103.

[0042] Specifically, there are two sets of the annular magnets 102, respectively arranged on both sides of the plane where the diaphragm 103 is located; the coil 104 is within the magnetic gap between the two sets of the annular magnets 102.

[0043] Specifically, the width or diameter of the acoustic opening 106 is 2 - 6 times the annular width of the annular magnet 102. At this time, the acoustic opening 106 has sufficient opening space to allow the vertical displacement of the radiating surface facing the acoustic opening 106 at the center of the diaphragm 103 to be significantly higher than the magnet surface facing the diaphragm 103, which can reduce the size of the magnetic gap between the two sets of the annular magnets 102, increase the air volume displacement and sound generation, improve the sensitivity, and reduce the energy consumption. However, tests show that when the width or diameter of the acoustic opening 106 is less than 2 times the annular width of the annular magnet 102 or greater than 6 times the annular width of the annular magnet 102, the overall sensitivity of the electromagnetic transducer 100 is reduced by at least 10%, and the distortion rate is increased by at least 5%.

[0044] Specifically, the transition surface 108 is arc-shaped in the radial cross-section of the annular magnet 102.

[0045] Specifically, the arc curve of the transition surface 108 in the radial cross-section of the annular magnet 102 is obtained based on a Bessel polynomial of order n. The Bessel polynomial of order n is as follows:

[0046]

[0047] where r(q)|q = 0 and r(q)|q = 1 represent the starting point and the ending point of the arc curve respectively, q is the curve parameter after normalization, and k = 0, 1, 2,..., n.

[0048] Specifically, the arc curve of the transition surface 108 in the radial cross-section of the annular magnet 102 is obtained based on a Bessel polynomial of order four with five control points 110. Please refer to Figure 3 .

[0049] Specifically, the positions of the control points 110 are obtained by the following method: taking the positions of the control points 100 as the input, and the sensitivity and distortion rate of the entire electromagnetic transducer 100 as the output, a neural network model is established; the measured data set is input into the neural network model for training, the adaptive moment estimation algorithm is used to calculate the error between the predicted value and the corresponding actual value, and the weights and bias coefficients of the neural network model are modified layer by layer according to the error to obtain a trained neural network model; based on the neural network model, optimization calculations are performed with the sensitivity and distortion rate as the objectives, and the positions of the control points 100 corresponding to the optimal solution are selected.

[0050] Specifically, the neural network model includes an input layer, six hidden layers, and an output layer; an input layer is connected to an output layer through six hidden layers in sequence, and the six hidden layers are connected in sequence. The input layer mainly consists of five neurons, each hidden layer mainly consists of ten neurons, and the output layer mainly consists of two neurons. The output layer outputs the sensitivity and distortion rate output by the electromagnetic transducer 100 respectively.

[0051] Specifically, the modification of the weights and bias coefficients of the neural network model layer by layer according to the error is specifically as follows: the error is recorded as the first error, the first error is differentiated and then multiplied by the first error coefficient and applied to the hidden layer connected to the output layer to modify the original weights and original biases of the hidden layer connected to the output layer, and the new weights and new biases of the current hidden layer are obtained; then, the error between the original biases and original weights and the new weights and new biases of the current hidden layer is calculated and recorded as the second error, the second error is differentiated and then multiplied by the second error coefficient and then applied to the previous hidden layer to modify the original weights and original biases of the previous hidden layer, and the new weights and new biases of the previous hidden layer are obtained; until all hidden layers are modified.

[0052] Specifically, the optimization calculation adopts a genetic algorithm, a simulated annealing algorithm, or a particle swarm algorithm.

[0053] Specifically, one or more of the mountings 101 include a first compliant gasket and a second compliant gasket, and the diaphragm 103 is mounted between the first compliant gasket and the second compliant gasket.

[0054] Specifically, the air guiding structure 109 is a rib, and the ribs are arranged at equal intervals in the circumferential direction on the outer surface of the annular magnet 102 and are centrosymmetrically distributed.

[0055] Specifically, the ribs are linear or arc-shaped.

[0056] Specifically, the length direction of the ribs is the radial direction of the annular magnet 102, see Figure 4 .

[0057] Specifically, the length direction of the ribs forms an angle greater than 0° and less than 90° with the radial direction of the annular magnet 102.

[0058] The annular magnet 102 extends around the central axis 105 to define an acoustic opening 106 radially inward from the mounting profile, allowing the vertical displacement of the radiation surface facing the acoustic opening 106 at the center of the diaphragm 103 to be significantly higher than that of the magnet surface facing the diaphragm 103, increasing the air volume displacement and sound generation, improving the sensitivity, and reducing the energy consumption; by providing a transition surface 108 at the acoustic opening 106, the acoustic wave reflection at the acoustic opening can be reduced, which not only provides a larger displacement space for the diaphragm 103 but also reduces the distortion rate of the generated sound; the air guiding structure 109 on the outer surface of the annular magnet 102 guides the air between the diaphragm 103 and the annular magnet 102 to flow quickly and uniformly, and can prevent the diaphragm 103 from contacting the annular magnet 102 over a large area, which also achieves the technical effects of improving the sensitivity and reducing the distortion rate.

[0059] The present invention provides a planar headphone with an air guiding structure, which includes an electromagnetic transducer 100; the electromagnetic transducer 100 includes: a mounting member 101, an annular magnet 102, a diaphragm 103 and a coil 104; wherein, an acoustic opening 106 is provided at the geometric center of the annular magnet 102; the diaphragm 103 is mounted on the mounting member 101 and includes a radiation surface facing the acoustic opening 106; the coil 104 is located on the diaphragm 103 and within the magnetic field of the annular magnet 102; the diaphragm 103 at least has a central region without the coil 104 arranged and axially aligned with the acoustic opening 106. When the electromagnetic transducer 100 is driven by an audio signal, the central region generates sound that propagates into the surrounding environment through the acoustic opening 106; the surface of the annular magnet 102 close to the diaphragm 103 and the inner side surface close to the central axis 105 are connected by a transition surface 108, and at least the transition surface 108 is provided with a plurality of air guiding structures 109 protruding from the annular magnet 102 and facing the diaphragm 103; it can improve the sensitivity and reduce the distortion rate.

[0060] It should be noted that the above content is a further detailed description of the present invention in combination with specific implementation manners. It cannot be determined that the specific implementation manners of the present invention are limited thereto. Under the guidance of the above embodiments, those skilled in the art can make various improvements and deformations on the basis of the above embodiments, and these improvements or deformations fall within the protection scope of the present invention.

Claims

1. A flat earphone with an air guiding structure, characterized in that Comprising an electromagnetic transducer; the electromagnetic transducer includes: One or more mounting members having a mounting profile extending around a central axis, wherein the mounting profile does not move along the central axis; A ring magnet extending around the central axis to define an acoustic opening radially inward from the mounting profile; the width or diameter of the acoustic opening is 2 - 6 times the annular width of the ring magnet; A diaphragm mounted on the one or more mounting members and including a radiating surface facing the acoustic opening; and One or more coils located on the diaphragm and within the magnetic field of the ring magnet; The diaphragm at least has a central region without a coil arrangement and axially aligned with the acoustic opening. When the electromagnetic transducer is driven by an audio signal, the central region generates sound that propagates through the acoustic opening into the surrounding environment; The surface of the ring magnet close to the diaphragm and the inner side close to the central axis are connected by a transition surface. At least the transition surface is provided with a plurality of air guiding structures protruding from the ring magnet towards the diaphragm; the arc curve of the transition surface in the radial section of the ring magnet is obtained based on a Bezier fourth-order polynomial with five control points; the positions of the control points are obtained by the following method: taking the positions of the control points as inputs and the sensitivity and distortion rate of the entire electromagnetic transducer as outputs, establishing a neural network model; inputting a measured data set into the neural network model for training, calculating the error between the predicted value and the corresponding actual value using the adaptive moment estimation algorithm, and modifying the weights and bias coefficients of the neural network model layer by layer according to the error to obtain a trained neural network model; performing optimization calculations with the sensitivity and distortion rate as the objectives based on the neural network model, and selecting the positions of the control points corresponding to the optimal solution; The air guiding structure is a rib, and the ribs are arranged at equal intervals in the circumferential direction on the outer surface of the ring magnet and are centrosymmetrically distributed; the ribs are linear or arc-shaped; the length direction of the ribs is the radial direction of the ring magnet; the length direction of the ribs forms an angle greater than 0° and less than 90° with the radial direction of the ring magnet.

2. The flat earphone with an air guiding structure according to claim 1, wherein, There are two groups of the ring magnets, respectively arranged on both sides of the plane where the diaphragm is located; the coils are within the magnetic gap between the two groups of the ring magnets.

3. The flat earphone with an air guiding structure according to claim 1 or 2, characterized in that, The transition surface is arc-shaped in the radial section of the ring magnet.

4. The flat earphone with an air guiding structure according to claim 3, characterized in that, The arc curve of the transition surface in the radial section of the ring magnet is obtained based on a Bezier nth-order polynomial.

5. The flat earphone with an air guiding structure according to claim 4, wherein, The neural network model includes an input layer, six hidden layers, and an output layer; an input layer is sequentially connected to an output layer through six hidden layers, and the six hidden layers are sequentially connected. The input layer mainly consists of five neurons, each hidden layer mainly consists of ten neurons, and the output layer mainly consists of two neurons. The output layer outputs the sensitivity and distortion rate output by the electromagnetic transducer respectively.

6. The flat earphone with an air guiding structure according to claim 5, wherein Modify the weights and bias coefficients of the neural network model layer by layer according to the error, specifically: Denote the error as the first error, take the partial derivative of the first error and multiply it by the first error coefficient, then apply the result to the hidden layer connected to the output layer to modify the original weights and original bias of the hidden layer connected to the output layer, and obtain the new weights and new bias of the current hidden layer; Then, calculate the error between the original bias and original weights and the new weights and new bias of the current hidden layer and denote it as the second error, take the partial derivative of the second error and multiply it by the second error coefficient, and then apply the result to the previous hidden layer to modify the original weights and original bias of the previous hidden layer, and obtain the new weights and new bias of the previous hidden layer; Until all hidden layers are modified.

7. The flat earphone with an air guiding structure according to claim 6, characterized in that, The optimization calculation adopts a genetic algorithm, a simulated annealing algorithm or a particle swarm algorithm.

8. The flat earphone with an air guiding structure according to claim 1 or 2, characterized in that, Wherein the one or more mounting members include a first compliant gasket and a second compliant gasket, and wherein the diaphragm is mounted between the first compliant gasket and the second compliant gasket.

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