Speaker displacement detection device and sound system

Abstract

This invention provides a loudspeaker displacement detection device and an audio system that is unaffected by the magnetic field generated by the voice coil and uses the magnetic flux generated by the magnet to detect the displacement of the loudspeaker's vibration system. The vibration system of the passive radiator (3) vibrates through air vibration generated inside the housing (8) by the vibration of the loudspeaker's (2) vibration system. A sensor (4) installed on the fixing system of the passive radiator (3) detects the magnetic flux vector acting from the magnet fixed to the vibration system of the passive radiator (3). Based on the magnetic flux vector detected by the sensor (4), the displacement (X2) of the vibration system of the passive radiator (3) is measured and converted into the displacement (X1) of the loudspeaker's (2) vibration system.

Description

Technical Field

[0001] This invention relates to a technique for detecting the displacement of a loudspeaker's vibration system. Background Technology

[0002] As a technique for detecting the displacement of a vibration system such as a speaker's diaphragm, the following technique is known: a magnet for displacement detection is fixed to the speaker's vibration system, and a magnetic angle sensor installed in the speaker's fixing system is used to detect the angle between the magnetic vector generated by the magnet for displacement detection and the magnetic flux vector generated by the magnetic circuit installed in the speaker's fixing system, and the displacement of the speaker's vibration system is detected based on the detected angle of the composite vector (for example, Patent Document 1).

[0003] [Existing Technical Documents] Patent documents Patent Document 1: Japanese Patent Application Publication No. 2022-149259 Summary of the Invention

[0004] According to the aforementioned technique for detecting the displacement of a loudspeaker's vibration system using a magnetic angle sensor, the magnetic field generated by the current flowing in the loudspeaker's voice coil interferes with the detection of the composite vector, sometimes making it impossible to detect the displacement correctly.

[0005] Therefore, the technical problem of the present invention is to eliminate the influence of the magnetic field generated by the current flowing in the voice coil of the loudspeaker from the detection of the displacement of the vibration system of the loudspeaker that utilizes the magnetic flux generated by the magnet.

[0006] To address the aforementioned technical problem, the present invention provides a loudspeaker displacement detection device comprising: a magnet fixed to a vibrating body, the vibrating body being vibrated by air vibrations generated by the vibration of the loudspeaker's vibration system; a sensor disposed on a fixed body fixed relative to the loudspeaker's fixing system; a displacement detection unit; and a displacement conversion unit. Here, the sensor detects the magnetic flux vector acting on the magnet, the displacement detection unit uses the detected value of the magnetic flux vector to detect the displacement of the passive radiator's vibration system, and the displacement conversion unit converts the displacement of the passive radiator's vibration system detected by the displacement detection unit into the displacement of the loudspeaker's vibration system according to the relationship between the displacement of the passive radiator's vibration system and the displacement of the loudspeaker's vibration system.

[0007] Furthermore, to address the aforementioned technical problem, the present invention provides a loudspeaker displacement detection device comprising: a displacement detection magnet, which is a magnet fixed to the vibration system of a passive radiator, the passive radiator being fixed to a housing, the vibration system of the passive radiator vibrating by air vibration generated within the housing due to the vibration of the loudspeaker's vibration system, the loudspeaker being fixed to the housing; a sensor fixed to the passive radiator's fixing system; a displacement detection unit; and a displacement conversion unit. Here, the sensor detects the magnetic flux vector acting on the displacement detection magnet; the displacement detection unit uses the detected value of the magnetic flux vector to detect the displacement of the passive radiator's vibration system; and the displacement conversion unit converts the displacement of the passive radiator's vibration system detected by the displacement detection unit into the displacement of the loudspeaker's vibration system according to the relationship between the displacement of the passive radiator's vibration system and the displacement of the loudspeaker's vibration system.

[0008] Alternatively, a magnet, i.e. a fixed system magnet, can be provided in the displacement detection device of such a loudspeaker, which is fixed to the fixed system magnet of the passive radiator. In the sensor, the angle between the magnetic flux vector of the displacement detection magnet acting on the sensor and the magnetic flux vector of the fixed system magnet is detected. In the displacement detection unit, the displacement of the vibration system of the passive radiator is detected based on the angle of the combined magnetic flux vector.

[0009] Alternatively, in the above-mentioned loudspeaker displacement detection device, the displacement conversion unit may be a filter having a transfer function that converts the displacement of the passive radiator's vibration system into the displacement of the loudspeaker's vibration system.

[0010] According to the above-described loudspeaker displacement detection device, a sensor can be placed at a position far from the voice coil of the loudspeaker and unaffected by the magnetic field generated by the voice coil, and the displacement of the loudspeaker's vibration system can be detected.

[0011] In addition, the present invention also provides an audio system comprising: a displacement detection device for the above-mentioned loudspeaker; a sound source device for outputting an audio signal; and a signal processing unit for performing signal processing on the audio signal output by the sound source device in accordance with the displacement of the vibration system of the loudspeaker after conversion by the displacement conversion unit, and outputting the signal to the loudspeaker.

[0012] [Invention Effects] As described above, according to the present invention, the influence of the magnetic field generated by the current flowing in the voice coil of the loudspeaker can be eliminated from the detection of the displacement of the vibration system of the loudspeaker that utilizes the magnetic flux generated by the magnet. Attached Figure Description

[0013] Figure 1 This is a diagram showing the structure of an audio system according to an embodiment of the present invention.

[0014] Figure 2 This is a diagram showing the relationship between the loudspeaker and the passive radiator in an embodiment of the present invention.

[0015] Figure 3 This is a diagram showing the structure of a loudspeaker according to an embodiment of the present invention.

[0016] Figure 4 This is a diagram showing the structure of a passive radiator according to an embodiment of the present invention.

[0017] Figure 5 This is a diagram representing the displacement transfer model from the loudspeaker to the passive radiator. Detailed Implementation

[0018] The embodiments of the present invention will be described below.

[0019] Figure 1 This describes the structure of the audio system in this embodiment.

[0020] As shown in the figure, the audio system includes: a sound source device 1, a loudspeaker 2, a passive radiator 3, a sensor 4 provided with the passive radiator 3, a signal processing device 5 that performs prescribed signal processing on the audio signal output from the sound source device 1 and outputs it to the loudspeaker 2, a displacement detection unit 6 that measures the displacement X2 of the vibration system of the passive radiator 3 based on the output of the sensor 4, and a displacement conversion unit 7 that converts the displacement X2 into the displacement X1 of the vibration system of the loudspeaker 2.

[0021] Here, the signal processing performed by the signal processing device 5 includes, for example, processing to correct the audio signal based on displacement X1 to eliminate distortion of the output of the speaker 2, and processing to limit the audio signal output to the speaker 2 based on displacement X1 so that the displacement range of the vibration system of the speaker 2 does not deviate from the specified range.

[0022] Next, as Figure 2 As shown, the speaker 2 and the passive radiator 3 are fixed in a manner that closes the opening in the housing 8 to seal the housing 8.

[0023] Figure 3 The 'a' indicates the structure of speaker 2.

[0024] As shown in the figure, the loudspeaker 2 has a yoke 201, a magnet 202, a top plate 203, a voice coil frame 204, a voice coil 205, a frame 206, a damper 207, a diaphragm 208, an edge 209, and a dust cover 210. Here, the vibration system of the loudspeaker 2 includes the diaphragm 208 and the voice coil frame 204, and the fixing system of the loudspeaker 2 includes the yoke 201, the magnet 202, the top plate 203, and the frame 206.

[0025] Now, Figure 3 In the diagram 'a', the upper part is designated as the front of speaker 2, and the lower part as the rear of speaker 2, as shown below. Figure 2 As shown, the outer edge of the frame 206 is fixed to the edge of the opening of the housing 8 in such a way that the front of the speaker 2 is in the outward direction of the housing 8.

[0026] Next, the magnetic yoke 201 has a forward-protruding protrusion 2011 in its central part, and an annular magnet 202 is provided on the outer periphery of the protrusion 2011. An annular top plate 203 is provided on the magnet 202. Moreover, the magnetic yoke 201, the magnet 202, and the top plate 203 form a magnetic circuit 220.

[0027] The voice coil frame 204 has a hollow cylindrical shape, and a voice coil 205, to which an audio signal from the signal processing device 5 is applied, is wound around its outer periphery. Furthermore, the protrusion 2011 of the yoke 201 is inserted from the rear into the hollow portion of the voice coil frame 204 in a manner that allows the voice coil frame 204 to move back and forth relative to the yoke 201. The voice coil 205 is positioned between the protrusion 2011 of the yoke 201 and the top plate 203, at a location through which the magnetic flux generated by the magnetic circuit 220 passes.

[0028] The diaphragm 208 has a shape that is approximately the same as the side of a frustum with the front-rear direction of the speaker 2 as its height direction, and its outer peripheral end is connected to the front end of the frame 206 via edge 209. In addition, the inner peripheral end of the diaphragm 208 is fixed to the front end of the voice coil frame 204.

[0029] In this speaker 2 structure, when an audio signal is applied to the voice coil 205 from the signal processing device 5, the voice coil frame 204 vibrates back and forth according to the amplitude of the audio signal through the electromagnetic interaction between the magnetic flux generated from the magnetic circuit 220 and the signal flowing in the voice coil 205. Furthermore, when the voice coil frame 204 vibrates, the resonating plate 208 connected to the voice coil frame 204 vibrates, producing sound corresponding to the audio signal.

[0030] Here, as in Figure 3 As shown in b, the rear surface of the speaker 2 is exposed relative to the interior of the housing 8.

[0031] then, Figure 4 Figure a shows the structure of the passive radiator 3.

[0032] As shown in the figure, the passive radiator 3 has a frame 301, a damper 302, a vibrating plate 303, an edge 304, a central cylindrical portion 305 connected to the inner periphery of the vibrating plate 303, a top plate 306, and a base 307. Here, the vibration system of the passive radiator 3 includes the vibrating plate 303 and the central cylindrical portion 305, and the fixing system of the passive radiator 3 includes the frame 301, the top plate 306, and the base 307.

[0033] Now, let's define the upper part of the diagram as the front of passive radiator 3, and the lower part as the rear of passive radiator 3, as follows: Figure 2 As shown, the outer edge of the frame 301 is fixed to the edge of the opening of the housing 8 in such a way that the front of the speaker 2 is in the outward direction of the housing 8.

[0034] Here, the front end of the central cylindrical section 305 is blocked, and a displacement detection magnet 308 is fixed at the rear end of the central cylindrical section 305. In addition, a sensor 4 is fixed at the top plate 306 at the position through which the magnetic flux generated by the displacement detection magnet 308 passes.

[0035] In addition, a magnet 309 is provided close to the sensor 4 between the top plate 306 and the base 307. Moreover, the magnet 309, the top plate 306, and the base 307 form a magnetic circuit 320, generating magnetic flux through the sensor 4.

[0036] Here, at the position of sensor 4, the direction of the magnetic flux generated by the displacement detection magnet 308 is approximately orthogonal to the direction of the magnetic flux generated by the magnetic circuit 320.

[0037] Sensor 4 is a magnetic angle sensor, such as Figure 4 As shown in b, the angle of the combined vector Q, which is the magnetic flux vector Qc acting from the magnetic circuit 320 and the magnetic flux vector Qs acting from the displacement detection magnet 308, is detected and output. Because the displacement of the displacement detection magnet 308, which is associated with the displacement of the central cylindrical portion 305 following the displacement of the vibrating plate 303, changes the magnetic flux vector Qs acting on the displacement detection magnet 308 of the sensor 4, this angle becomes a value corresponding to the displacement of the vibration system of the passive radiator 3.

[0038] Here, as in Figure 4 As shown in 'c', the rear surface of the vibrating plate 303 is exposed relative to the interior of the housing 8.

[0039] Furthermore, as described above, the rear surface of the diaphragm 208 of the loudspeaker 2 and the rear surface of the passive radiator 3 are exposed relative to the interior of the housing 8. Therefore, as the vibration system of the loudspeaker 2 vibrates, the air inside the housing 8 vibrates, and as the air inside the housing 8 vibrates, the vibration system of the passive radiator 3 vibrates.

[0040] Therefore, there is a certain relationship between the displacement X1 of the vibration system of loudspeaker 2 and the displacement X2 of the vibration system of passive radiator 3.

[0041] In addition, the passive radiator 3 is generally set up to improve the sound quality of the output sound of the speaker 2.

[0042] return Figure 1 The displacement detection unit 6 measures the displacement of the vibration system of the passive radiator 3 based on the output of the sensor 4, and outputs it as displacement X2 to the displacement conversion unit 7.

[0043] The displacement conversion unit 7 converts the displacement X2 of the vibration system of the passive radiator 3 into the displacement X1 of the vibration system of the loudspeaker 2, and outputs it to the signal processing device 5.

[0044] The conversion from displacement X2 to displacement X1 in the displacement conversion unit 7 is performed as follows, for example.

[0045] That is, the values ​​of displacement X1 corresponding to each value of displacement X2 are obtained in advance through actual measurement and simulation, and stored as corresponding information in the displacement conversion unit 7. Then, in the displacement conversion unit 7, the value of displacement X1 corresponding to the value of displacement X2 output from the displacement detection unit 6 is obtained according to the stored corresponding information and output to the signal processing device 5.

[0046] Alternatively, regarding the conversion from displacement X2 to displacement X1, the displacement conversion unit 7 is configured as a filter that converts displacement X2 into displacement X1. The displacement X2 output from the displacement detection unit 6 is converted into the value of displacement X1 by the filter and output to the signal processing device 5.

[0047] In this case, the filter's transfer function F can be expressed by expression 1 as x1 = F(x2).

[0048] [Formula 1] Equation 1 represents the transfer function F that attenuates high-frequency components through LPF after transforming displacement X2 into displacement X1, where s represents the Laplace operator, and ω n ζ represents the cutoff angular frequency of the LPF, and ζ represents the attenuation ratio of the LPF.

[0049] In addition, Ka, M ms2 R ms2 K ms2 According to Figure 5 The variables in the displacement transfer model shown are Ka and M, which are based on the air spring constant of the outer casing 8. ms2 R is the movable mass (vibration system mass) of the passive radiator 3. ms2 K is the attenuation coefficient of passive radiator 3.ms2 It is the spring constant of passive radiator 3.

[0050] in addition, Figure 5 M in the model ms1 It is the movable mass (vibration system mass) of speaker 2, R ms1 K is the attenuation coefficient of speaker 2. ms1 is the spring constant of speaker 2, B is the magnetic force through the voice coil of speaker 2, l is the length of the voice coil, Re is the resistive component of the voice coil of speaker 2, Le is the inductance of the voice coil of speaker 2, and u is the input voltage.

[0051] The embodiments of the present invention have been described above.

[0052] According to this embodiment, the sensor 4 can be positioned at a location far from the voice coil of the speaker 2 and unaffected by the magnetic field generated by the current flowing through the voice coil, and the displacement of the vibration system of the speaker 2 can be detected.

[0053] In this embodiment, the passive radiator 3 can also be replaced with any vibrating body that vibrates through air vibration generated by the vibration of the vibration system of the loudspeaker 2. In this case, the displacement detection magnet 308 is fixed to the vibrating body, and the sensor 4 and the magnetic circuit 320 are arranged on a fixed body fixed relative to the fixing system of the loudspeaker 2.

[0054] [Explanation of reference numerals in the attached figures] 1…Sound source device, 2…loudspeaker, 3…passive radiator, 4…sensor, 5…signal processing device, 6…displacement detection unit, 7…displacement conversion unit, 8…outer shell, 201…magnetic yoke, 202…magnet, 203…top plate, 204…voice coil skeleton, 205…voice coil, 206…frame, 207…damper, 208…vibrating plate, 209…edge, 210…dust cover, 301…frame, 302…damper, 303…vibrating plate, 304…edge, 305…central cylindrical part, 306…top plate, 307…base, 308…magnet for displacement detection, 309…magnet, 320…magnetic circuit.

Claims

1. A displacement detection device for a loudspeaker, characterized in that, have: A magnet is fixed to a vibrating body, which vibrates through air vibrations generated by the vibration of the speaker's vibration system; The sensor is mounted on a fixed body that is fixed relative to the speaker's mounting system; Displacement detection unit; as well as Displacement transformation unit, The sensor detects the magnetic flux vector acting on the magnet. The displacement detection unit uses the detected value of the magnetic flux vector of the sensor to detect the displacement of the vibration system of the passive radiator. The displacement conversion unit converts the displacement of the passive radiator's vibration system detected by the displacement detection unit into the displacement of the speaker's vibration system based on the relationship between the displacement of the passive radiator's vibration system and the displacement of the speaker's vibration system.

2. A displacement detection device for a loudspeaker, characterized in that, have: The displacement detection magnet is a magnet fixed to the vibration system of a passive radiator. The passive radiator is fixed to the housing. The vibration system of the passive radiator vibrates by air vibration generated inside the housing due to the vibration of the speaker's vibration system. The speaker's fixing system is fixed to the housing. Sensor, fixed system attached to passive radiator; Displacement detection unit; and Displacement transformation unit, The sensor detects the magnetic flux vector acting on the displacement detection magnet. The displacement detection unit uses the detected value of the magnetic flux vector of the sensor to detect the displacement of the vibration system of the passive radiator. The displacement conversion unit converts the displacement of the vibration system of the passive radiator detected by the displacement detection unit into the displacement of the vibration system of the loudspeaker according to the relationship between the displacement of the vibration system of the passive radiator and the displacement of the vibration system of the loudspeaker.

3. The loudspeaker displacement detection device according to claim 2, characterized in that, A magnet having a fixed system attached to the passive radiator is called a fixed system magnet. The sensor detects the angle between the magnetic flux vector of the displacement detection magnet acting on the sensor and the magnetic flux vector of the magnet in the fixing system, which is the resultant magnetic flux vector. The displacement detection unit detects the displacement of the vibration system of the passive radiator based on the angle of the synthesized magnetic flux vector.

4. The loudspeaker displacement detection device according to claim 2, characterized in that, The displacement conversion unit is a filter having a transfer function that converts the displacement of the vibration system of the passive radiator into the displacement of the vibration system of the loudspeaker.

5. A sound system, characterized in that, have: The displacement detection device for the loudspeaker according to any one of claims 1 to 4; Audio source device, outputting audio signals; as well as The signal processing unit performs signal processing on the audio signal output by the sound source device, corresponding to the displacement of the speaker's vibration system after conversion by the displacement conversion unit, and outputs the signal to the speaker.

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