RU214341U1 - SOUND TRANSDUCER BASED ON HALBACH MAGNETIC ASSEMBLY - Google Patents

Abstract

The utility model relates to the field of acoustic systems, in particular to sound converters of an electrical signal into sound for sound reproduction systems. The technical result of the proposed utility model is to improve the quality of the audio signal transmission. The technical result is achieved in a sound transducer based on a Halbach magnetic assembly, containing a dielectric diaphragm, on which a conductive voice coil is applied, having several longitudinal conductive tracks, there is a Halbach magnetic matrix containing magnets having a shape elongated along the longitudinal conductive tracks, made to ensure the creation of power magnetic field lines perpendicular to the longitudinal axis of the magnet, the Halbach magnetic matrix is oriented by magnetic field lines to the voice coil so that the magnetic field lines intersect the voice coil, causing the Lorentz force to move the diaphragm in the direction normal to its surface, the magnets are located on both sides relative to the surface of the diaphragm , magnets are located at a distance from each other, the number of magnets on one side of the diaphragm is m>5, on the first side of the diaphragm, the magnets are placed along the conductive tracks and in the gaps between them, the magnets and the diaphragm are closed epleny in the body. Magnets located along the conductive tracks are located at a greater distance from the diaphragm than magnets located in the gaps between the conductive tracks. 6 ill.

Description

The utility model relates to the field of acoustic systems, in particular to sound converters of an electrical signal into sound for sound reproduction systems.

An analogue is known - a sound transducer - US4337379, 29.01.82, containing a diaphragm, magnets located at a distance from the diaphragm with the effect of their electromagnetic field on the diaphragm, and the magnets are arranged in the form of a matrix with columns and rows so that nearby magnets have opposite poles, the conductive track is located on the diaphragm with the formation of a continuous current path, passing with alternating direction along the columns and along the rows, in the intervals between the above nearby magnetic poles, not passing by two consecutive magnetic poles from one column or one row, ensuring the passage of the magnetic flux created by the magnets through the respective portions of the current path at right angles and in the same direction with respect to the direction of the current, the conductive track has enlarged current flow portions in the regions of the outermost magnets in the array to provide a small impedance in the portions.

The disadvantage of analog is the low level of sensitivity of the matrix emitter. Sensitivity is expressed in the degree of change in sound pressure with a change in the input electrical power. A low level of sensitivity requires an increase in the electrical power input to achieve the required sound level, which limits the use of the device. This makes the device unsuitable for use in self-powered speakers: wireless headphones, portable players, smartphones, tablets, laptops; as well as in devices with weak amplification: using budget sound cards, sound devices without a specialized powerful amplifier.

The magnetic assembly of Halbach is known - a source on the Internet https://ru.wikiеdia.org/wiki/Magnetic_assembly_Halbach - special

configuration of permanent magnets, characterized by the fact that the magnetic field on one of its sides is almost completely absent due to the special arrangement of the magnets in the assembly. The described effect is reproduced by repeating the sequence of magnetic elements by the magnetization vector (on the front surface) to the left, up, right, down, left.

An analogue is known - a sound transducer based on the Halbach magnetic assembly - US9894442, 02/13/2018, adopted as a prototype, containing a diaphragm that can move along the central axis, while the diaphragm has a dielectric surface, there is a voice coil connected to the dielectric surface of the diaphragm, moreover, the voice coil includes a conductive winding having one or more conductive turns on the dielectric surface of the diaphragm, while one or more conductive turns pass along the dielectric surface of the diaphragm around the central axis, there is a Halbach magnetic matrix, including at least three magnets located sideways side by side, with each magnet located along its longitudinal axis to ensure the creation of magnetic field lines perpendicular to the longitudinal axis of the magnet, while the Halbach magnetic matrix is oriented by magnetic field lines to the voice coil so that the magnetic lines strong fields cross the voice coil, causing the Lorentz force to move the diaphragm along the central axis.

The prototype is more sensitive than the previous counterpart. The disadvantage of the prototype is the poor sound quality due to the presence of distortion of the transmitted signal.

The technical result of the proposed utility model is to improve the quality of the audio signal transmission.

The technical result is achieved in a sound transducer based on a Halbach magnetic assembly, containing a dielectric diaphragm, on which a conductive voice coil is applied, having several longitudinal conductive tracks, there is a Halbach magnetic matrix containing magnets having a shape elongated along the longitudinal conductive tracks, made to ensure the creation of power magnetic field lines perpendicular to the longitudinal axis of the magnet, the Halbach magnetic matrix is oriented by magnetic field lines to the voice coil so that the magnetic field lines cross the voice coil, causing the Ampère force to move the diaphragm in the direction normal to its surface, the magnets are located on both sides relative to the surface of the diaphragm , magnets are located at a distance from each other, the number of magnets on one side of the diaphragm is m>5, on the first side of the diaphragm, the magnets are placed along the conductive tracks and in the gaps between them, the magnets and the diaphragm are closed captives in the case, the magnets located along the conductive paths are located at a greater distance from the diaphragm than the magnets located in the gaps between the conductive paths.

In FIG. 1 shows a section of a sound transducer based on a Halbach magnetic assembly in a plane perpendicular to the magnet axis.

In FIG. 2 shows the mutual arrangement of the conductive paths of the diaphragm and magnets in the plane of the diaphragm (in plan).

In FIG. 3 shows the appearance of a sound transducer based on the Halbach magnetic assembly.

In FIG. Figure 4 shows the configuration of the magnetic field in a section perpendicular to the axis of the magnets (bottom) and the diagram of the distribution of magnetic induction (top) along the section in a sound transducer based on the Halbach magnetic assembly.

In FIG. 5 shows the configuration of the magnetic field in a section perpendicular to the axis of the magnets (bottom) and the diagram of the distribution of magnetic induction (top) along the section in the prototype device.

In FIG. 6 shows the directions of forces that cause oscillations of the diaphragm, in a section perpendicular to the axis of the magnets of the prototype device.

The sound transducer based on the Halbach magnetic assembly contains a dielectric diaphragm 1, as shown in FIG. 1, on which a conductive voice coil 2 is applied, as shown in FIG. 2 having a plurality of longitudinal conductive tracks 3 as shown in FIG. 1, 2, there is a magnetic Halbach matrix containing magnets 4 having a shape elongated along the longitudinal conductive tracks 3, as shown in FIG. 2, designed to create magnetic field lines 5 perpendicular to the longitudinal axis 6 of the magnet 4, the Halbach magnetic matrix is oriented by the magnetic field lines 5 to the voice coil 2 so that the magnetic field lines 5 intersect the voice coil 2, causing the Ampere force to move the diaphragm 1 in the direction normal to its surface, the magnets 4 are located on both sides relative to the surface of the diaphragm 1, the magnets 4 are located at a distance L from each other, the number of magnets 4 on one side of the diaphragm 1 m>5, on the first side of the diaphragm 1, the magnets 4 are located in plan along the conductive tracks 3 and in the spaces 7 between them, the magnets 4 and the diaphragm 1 are fixed in the housing 8. The magnets 9 located along the conductive tracks 3 are located at a greater distance H from the diaphragm 1, as shown in FIG. 1 than the magnets 10 located in the gaps 7 between the conductive tracks 3 - the distance h.

Consider an example of a specific implementation of a sound transducer based on a Halbach magnetic assembly. Its general view is shown in Fig. 3. The layout of the magnets 4 corresponds to that shown in FIG. 1. Due to the location of the magnets on both sides relative to the diaphragm 1, a uniform distribution of magnetic induction B is achieved within the conductive tracks 3. The magnets 4 on the second side of the diaphragm 1 are located in the plan along the conductive tracks 3 and in the gaps 7 between them. The magnets 4 located along the conductive tracks 3 are located at a greater distance from the diaphragm 1 than the magnets 4 located in the gaps 7 between the conductive tracks 3. Due to the indicated arrangement of the magnets 4, a uniform distribution of the magnetic induction B is achieved within the conductive tracks 3. Uniformity is achieved by mutual influence magnetic fields of magnets 4. Flexible dielectric thin-film diaphragm 1 is mounted on an insulating frame in housing 8. Magnets 4 are installed in housing 8, due to this their spatial position relative to conductive track 1 and isolation from each other and from diaphragm 1 are set. 8 and an insulating frame (not shown in the drawing) are fixed to each other. Body parts 8 are made by milling on a CNC machine. The body 8 can be made from a single piece by injection molding. In this case, diaphragm 1 and magnets 4 are installed as embedded elements during the casting process. Case 8 can be 3d printed.

Consider an example of the operation of a sound transducer based on a Halbach magnetic assembly. The ends 12 of the voice coil 2 (Fig. 2) are connected to a source of electrical sound signal - a music player. The interaction of the coil 2 and its sections, the longitudinal conductive tracks 3, through which the current flows, with the magnetic field 5 of the magnets 4 creates forces that cause the diaphragm 1 to move. The result of such movements is sound. Due to the fact that the longitudinal magnets 4 are located at a distance L from each other, it is possible to place the magnets on both sides relative to the diaphragm 1. If they are located close, as in the prototype, they would close the diaphragm and prevent the passage of sound vibrations of the medium to the outside, which would reduce the quality of the audio signal. The location of the magnets 4 on both sides of the diaphragm 1 and their number (more than 5 on one side of the diaphragm) ensures the uniformity of the magnetic field within each section of the conductive track 3. This is illustrated in Figs. 4, 5. Section 13 of the graph of the distribution of magnetic induction B in the area of conductive tracks 3 of the proposed device (Fig. 4) is more uniform than section 14 of a similar graph of the prototype device (Fig. 5). The result of such an uneven distribution of magnetic induction B in the prototype device is the multidirectionality of the forces 15, as shown in FIG. 6, causing fluctuations in diaphragm 1. Due to the multidirectional forces, stresses and bends in the material of diaphragm 1 arise, which are a source of constant parasitic "standing waves" in it. This generates distortion of the transmitted audio signal in the prototype device. In the proposed sound transducer based on the Halbach magnetic assembly, such distortions are significantly reduced. In the described implementation example, they are reduced by a factor of twenty.

Claims (1)

A sound transducer based on a Halbach magnetic assembly, containing a dielectric diaphragm, on which a conductive voice coil is applied, having several longitudinal conductive tracks, there is a Halbach magnetic matrix containing magnets having a shape elongated along the longitudinal conductive tracks, made to ensure the creation of magnetic field lines, perpendicular to the longitudinal axis of the magnet, the Halbach magnetic matrix is oriented with magnetic field lines to the voice coil so that the magnetic field lines intersect the voice coil, causing the Lorentz force to move the diaphragm in the direction normal to its surface, characterized in that the magnets are located on both sides relative to the surface of the diaphragm , magnets are located at a distance from each other, the number of magnets on one side of the diaphragm is m>5, on the first side of the diaphragm, the magnets are placed along the conductive tracks and in the gaps between them, the magnets and the diaphragm are fixed in the housing All, moreover, the magnets located along the conductive tracks are located at a greater distance from the diaphragm than the magnets located in the gaps between the conductive tracks.

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