Speaker

Abstract

To provide a speaker for detecting whether or not there is an abnormality in an operation of a vibration part including a diaphragm.SOLUTION: In a speaker, detection parts 20x1, 20x2, 20y1, 20y2 are arranged within an angular range of 90 degrees with a center line O of a vibration part as a center on a plane surface projected onto a surface vertical to the center line O. The detection parts 20x1, 20x2, 20y1, 20y2 include: movable magnetic field generation elements 21x1, 21x2, 21y1, 21y2 arranged in a movable part; and magnetic sensors 22x1, 22x2, 22y1, 22y2 arranged in a support part. When an abnormality exists in a detection output from one of the detection parts, occurrence of a malfunction is determined.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a speaker having a detection unit that detects the movement of a vibration unit at multiple locations. [Background technology]

[0002] A conventional speaker with MFB (motion feedback) function is provided with a sensor that detects the vibration state of the vibration part including the voice coil and diaphragm, and the voice current supplied to the voice coil is feedback-controlled based on the detection output from the sensor.

[0003] The speaker described in Patent Document 1 has a bobbin with a voice coil wound around its base, the tip of the bobbin is attached to a cone-shaped diaphragm, and an acceleration sensor that detects the vibration of the bobbin is fixed to the tip of the bobbin. Furthermore, a balance ring is provided on the bobbin to eliminate the imbalance in mass distribution caused by the provision of the acceleration sensor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-245293 Summary of the Invention [Problem to be solved by the invention]

[0005] The speaker described in Patent Document 1 uses an acceleration sensor to detect the behavior of only one point on the bobbin. Therefore, if, for example, part of the vibrating part including the bobbin is damaged or a foreign object adheres to the vibrating part, causing the bobbin to tilt while vibrating or rolling during vibration, the detection output from the acceleration sensor alone cannot detect such abnormal behavior.

[0006] The present invention is intended to solve the above-mentioned conventional problems, and aims to provide a speaker that is equipped with a detection unit that detects the vibration state of the vibration unit and is further capable of detecting abnormal operation of the vibration unit. [Means for solving the problem]

[0007] The present invention provides a speaker provided with a vibration section having a voice coil and a diaphragm that vibrates together with the voice coil, and a support section to which a magnetic circuit section that applies magnetic flux to the voice coil is fixed, A plurality of detectors are provided to detect the movement of the vibration unit. 、 The detection unit includes a moving magnetic field generating element provided on the vibration unit to generate a moving magnetic field, and a magnetic sensor provided on the support unit to detect the moving magnetic field. And, When viewed in a plane projected onto a plane perpendicular to the center line extending in the vibration direction of the vibration unit, the plurality of detection units detects movement at different locations on the vibration unit.

[0008] In the speaker of the present invention, it is preferable that the detection unit detects movement at two locations positioned at an angle of 180 degrees around the center line when viewed on the plane.

[0009] It is further preferable that the speaker of the present invention be configured such that, when viewed on the plane, the detection unit detects movement at four locations positioned at 90-degree angles around the center line.

[0011] In this case, when viewed in the plane, it is preferable that the center of the magnetic sensor constituting each of the detection units and the center of the movable magnetic field generating element are located on the same line extending from the center line.

[0012] Furthermore, in the speaker of the present invention, the detection unit has a fixed magnetic field generating member provided on the support unit, It is preferable that the movable magnetic field generated by the movable magnetic field generating element and the fixed magnetic field generated by the fixed magnetic field generating member are detected by a magnetic sensor as magnetic field components in directions that intersect with each other. [Effects of the Invention]

[0014] In the speaker of the present invention, when viewed on a plane projected onto a plane perpendicular to the center line extending in the vibration direction of the vibrating part, the multiple detectors detect the movement of the vibrating part at different positions, making it possible to detect tilting or rolling in the vibration of the vibrating part, for example, when the vibrating part is damaged, a foreign object adheres to the vibrating part, or an assembly defect or part defect occurs. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view showing the overall structure of a speaker according to the present invention; [Figure 2] FIG. 2 is a half cross-sectional view of the speaker shown in FIG. 1 taken along line II-II; [Figure 3] 3 is a plan view of the center of the speaker shown in FIG. 1 with the phase plug removed, as seen in the direction of the arrows III-III shown in FIG. 2; [Figure 4] 3. An enlarged partial plan view of a part of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] In the speaker 1 of the first embodiment of the present invention shown in Figures 1 and 2, the Z1-Z2 direction is the front-to-rear direction, with the Z1 direction being the front and the Z2 direction being the rear. Either the Z1 direction or the Z2 direction is the main sound-producing direction. The Z1-Z2 direction is also the vibration direction of the vibrating unit. Figure 1 shows a center line O. The center line O passes through the center (center of gravity) of the vibrating unit and extends in the vibration direction (Z1-Z2 direction) of the vibrating unit. The main part of the speaker 1 has a nearly rotationally symmetric structure centered on the center line O. Figure 1 also shows the X-axis and Y-axis, which are orthogonal to each other in a plane perpendicular to the center line O. The X-direction is the first direction, and the Y-direction is the second direction.

[0017] The speaker 1 shown in Figures 1 and 2 has a frame 2. The frame 2 is made of a non-magnetic or magnetic material and has a tapered shape with a diameter that gradually widens toward the front (Z1 direction). A magnetic circuit section 10 is fixed to the rear (Z2 direction) of the frame 2 by means of adhesive, screws, or other such means. The frame 2 and magnetic circuit section 10 together form a "support section."

[0018] The magnetic circuit unit 10 has a ring-shaped drive magnet 11 centered on a center line O, a ring-shaped opposing yoke 12 joined to the front of the drive magnet 11, and a rear yoke 13 joined to the rear of the drive magnet 11. A center yoke 14 is integrally formed with the rear yoke 13. The center yoke 14 is located inside the drive magnet 11 and opposing yoke 12 and is formed to protrude forward (in the Z1 direction) from the rear yoke 13. Alternatively, the center yoke 14 may be formed separately from the rear yoke 13, and the rear yoke 13 and center yoke 14 may be joined together. A center hole 15 is formed in the center yoke 14 and penetrates in the front-to-rear direction (the Z1-Z2 direction). The opposing yoke 12, rear yoke 13, and center yoke 14 are made of a magnetic material, i.e., a magnetic metal material.

[0019] The center yoke 14 is cylindrical, and a magnetic gap G, which is a cylindrical space centered on the center line O, is formed between the outer circumferential surface of the center yoke 14 and the inner circumferential surface of the opposing yoke 12. In the magnetic circuit unit 10, the driving magnetic flux Fd emitted from the driving magnet 11 travels from the opposing yoke 12 across the magnetic gap G and circulates around the center yoke 14 and the rear yoke 13. In this speaker 1, the magnetic circuit unit 10 functions as a "fixed magnetic field generating member," and the leakage magnetic field from the magnetic circuit unit 10 acts on the magnetic sensor as a fixed magnetic field H1 directed toward the center line O, as shown in FIGS. 2 and 4.

[0020] A diaphragm 3 is provided inside the front portion of the frame 2. The diaphragm 3 has a conical shape. A front peripheral portion 2a of the frame 2 and an outer peripheral edge 3a of the diaphragm 3 are joined via an elastically deformable edge member 4. The edge member 4 and the front peripheral portion 2a, and the edge member 4 and the outer peripheral edge 3a are fixed with an adhesive. An inner peripheral fixing portion 2b is formed on the inner surface of the middle portion of the frame 2, and the outer peripheral portion 5a of an elastically deformable damper member 5 with a corrugated cross section is fixed to the inner peripheral fixing portion 2b with an adhesive.

[0021] As shown in FIG. 2, a bobbin 6 is provided inside the frame 2. The bobbin 6 has a cylindrical shape centered on a center line O. The inner peripheral end 3b of the diaphragm 3 is fixed to the outer peripheral surface of the bobbin 6 with an adhesive, and the inner peripheral portion 5b of the damper member 5 is also fixed to the outer peripheral surface of the bobbin 6 with an adhesive. A voice coil 7 is provided on the outer peripheral surface of the rear end of the bobbin 6 facing rearward (in the Z2 direction). The coated conductor that constitutes the voice coil 7 is wound a predetermined number of turns around the outer peripheral surface of the bobbin 6. The voice coil 7 is located within the magnetic gap G of the magnetic circuit unit 10.

[0022] The diaphragm 3 and bobbin 6 are supported by the frame 2 (with respect to the support part) so as to be able to vibrate freely in the front-to-back direction (Z1-Z2 direction) due to the elastic deformation of the edge member 4 and damper member 5. The diaphragm 3, bobbin 6, and voice coil 7 constitute a "vibration part" that vibrates in the front-to-back direction with respect to the "support part" including the frame 2. The Z1-Z2 direction is the vibration direction of the "vibration part." The edge member 4 and damper member 5 also constitute part of the "vibration part."

[0023] As shown in Fig. 3, the speaker 1 is provided with four pairs of detection units (vibration detection units) 20x1, 20x2, 20y1, and 20y2 that detect vibrations of the vibration unit. When viewed in a plane projected onto a plane perpendicular to the center line O, the four pairs of detection units 20x1, 20x2, 20y1, and 20y2 do not overlap with each other and are arranged at equal angular intervals around the center line O. The plan view of Fig. 3 shows a first detection center line Dx that passes through the center line O and extends in a first direction (X direction), and a second detection center line Dy that passes through the center line O and extends in a second direction (Y direction). The first detection center line Dx and the second detection center line Dy are perpendicular to each other at the center line O.

[0024] The detection units 20x1 and 20x2 are located on the first detection center line Dx. The detection units 20x1 and 20x2 are disposed at an angle of 180 degrees around the center line O. The detection units 20y1 and 20y2 are located on the second detection center line Dy. The detection units 20y1 and 20y2 are disposed at an angle of 180 degrees around the center line O. As a result, the detection units 20x1, 20x2, 20y1, and 20y2 are disposed at an angle of 90 degrees around the center line O. Furthermore, the distance from the center line O to the detection unit 20x1, the distance from the center line O to the detection unit 20x2, the distance from the center line O to the detection unit 20y1, and the distance from the center line O to the detection unit 20y2 are all the same.

[0025] The detection unit 20x1 is composed of a movable magnetic field generating element 21x1 fixed to the vibrating unit and a magnetic sensor 22x1 fixed to the support unit. The detection unit 20x2 is composed of a movable magnetic field generating element 21x2 fixed to the vibrating unit and a magnetic sensor 22x2 fixed to the support unit. The detection unit 20y1 is composed of a movable magnetic field generating element 21y1 fixed to the vibrating unit and a magnetic sensor 22y1 fixed to the support unit. The detection unit 20y2 is composed of a movable magnetic field generating element 21y2 fixed to the vibrating unit and a magnetic sensor 22y2 fixed to the support unit.

[0026] The movable magnetic field generating elements 21x1, 21x2, 21y1, and 21y2 are magnets. As shown in Figures 1 and 3, the movable magnetic field generating elements 21x1, 21x2, 21y1, and 21y2 are fixed to a ring-shaped fixing member 23, and as shown in Figure 2, the fixing member 23 is fixed to the front end of the bobbin 6 on the Z1 side. The fixing member 23 is made of a non-magnetic material such as a synthetic resin material.

[0027] The magnetization directions of the movable magnetic field generation elements 21x1, 21x2, 21y1, and 21y2 are all tangent directions to an imaginary circle centered on the center line O. The magnetization direction of the movable magnetic field generation element 21x1 is perpendicular to the first detection center line Dx, and in FIG. 3, the right end is the north pole and the left end is the south pole. The magnetization direction of the movable magnetic field generation element 21x2 is perpendicular to the first detection center line Dx, and in FIG. 3, the left end is the north pole and the right end is the south pole. The magnetization direction of the movable magnetic field generation element 21y1 is perpendicular to the second detection center line Dy, and in FIG. 3, the lower end is the north pole and the upper end is the south pole. The magnetization direction of the movable magnetic field generation element 21y2 is perpendicular to the second detection center line Dy, and in FIG. 3, the upper end is the north pole and the lower end is the south pole.

[0028] The centers between the N-pole and S-pole ends of the movable magnetic field generating elements 21x1 and 21x2, i.e., the centers dividing the movable magnetic field generating elements 21x1 and 21x2 in the left-right direction in the figure, are located on a first sensing center line Dx extending from the center line O. The centers between the N-pole and S-pole ends of the movable magnetic field generating elements 21y1 and 21y2, i.e., the centers dividing the movable magnetic field generating elements 21y1 and 21y2 in the top-bottom direction in the figure, are located on a second sensing center line Dy extending from the center line O.

[0029] As shown in FIG. 2, a bulkhead member 25 is fixed to the upper end of the center pole 14 of the magnetic circuit unit 10. The bulkhead member 25 is preferably made of a non-magnetic material. As shown in FIGS. 2 and 3, an upper surface 25a of the bulkhead member 25 is a plane perpendicular to the center line O. Printed wiring boards 26 are fixed to four locations on the upper surface 25a, and magnetic sensors 22x1, 22x2, 22y1, and 22y2 are mounted on each printed wiring board 26. The magnetic sensors 22x1, 22x2, 22y1, and 22y2 each have a built-in sensing element in a package. The sensing points of the sensing elements built into the magnetic sensors 22x1 and 22x2 are located approximately on the first sensing center line Dx, and the sensing points of the sensing elements built into the magnetic sensors 22y1 and 22y2 are located on the second sensing center line Dy. The opposing distance between the movable magnetic field generating element 21x1 and the magnetic sensor 22x1 on the first detection center line Dx, the opposing distance between the movable magnetic field generating element 21x2 and the magnetic sensor 22x2 on the first detection center line Dx, the opposing distance between the movable magnetic field generating element 21y1 and the magnetic sensor 22y1 on the second detection center line Dy, and the opposing distance between the movable magnetic field generating element 21y2 and the magnetic sensor 22y2 on the second detection center line Dy are all equal.

[0030] 3, terminal portions of wiring members 27 are fixed to each printed wiring board 26. The terminal portions of wiring members 27 are electrically connected to the terminals of magnetic sensors 22x1, 22x2, 22y1, and 22y2 via multiple conductive layers provided on printed wiring board 26. Wiring members 27 pass through center hole 15 of center yoke 14 and extend rearward (in the Z2 direction) beyond magnetic circuit unit 10.

[0031] A fixed magnetic field H1, which is a leakage magnetic flux of the driving magnetic flux Fd generated in the magnetic circuit unit 10, which is a fixed magnetic field generating member, acts on each of the magnetic sensors 22x1, 22x2, 22y1, and 22y2 in a direction toward the center line O. Furthermore, a movable magnetic field H2 generated from the movable magnetic field generating elements 21x1, 21x2, 21y1, and 21y2 acts on each of the magnetic sensors 22x1, 22x2, 22y1, and 22y2 in a tangential direction of a circle centered on the center line O. In other words, the fixed magnetic field H1 and the movable magnetic field H2 act on each of the magnetic sensors 22x1, 22x2, 22y1, and 22y2 in directions where they intersect each other.

[0032] To explain the operation of the four detection units 20x1, 20x2, 20y1, and 20y2, detection unit 20y2 is shown as a representative in Figure 4. A fixed magnetic field H1 facing in the second direction (Y direction), which is a leakage magnetic flux from magnetic circuit unit 10, which is a fixed magnetic field generating member, and a mobile magnetic field H2 facing in the first direction (X direction) generated by mobile magnetic field generating element 21y2 act on magnetic sensor 22y2 as magnetic field components that intersect (are orthogonal to) each other in the XY plane. In this speaker 1, magnetic circuit unit 10 functions as a "fixed magnetic field generating member." However, a fixed magnet separate from magnetic circuit unit 10 may be provided close to magnetic sensor 22y2, for example, on printed wiring board 26, and the component of the magnetic field emitted from this fixed magnet facing in the second direction (Y direction) may act on magnetic sensor 22y2 as fixed magnetic field H1.

[0033] The magnetic sensor 22y2 includes at least one magnetoresistive element built into the package as a sensing element. The magnetoresistive element is a GMR or TMR element having a pinned magnetic layer and a free magnetic layer. In a GMR or TMR element, the magnetization direction of the pinned magnetic layer is fixed, and the magnetization direction of the free magnetic layer changes in response to an external magnetic field. The electrical resistance value changes in response to a change in the relative angle between the direction of the pinned magnetic field of the pinned magnetic layer and the direction of magnetization of the free magnetic layer.

[0034] When the fixed magnetic field H1 and the movable magnetic field H2 act on the free magnetic layer of the magnetoresistive element built into the magnetic sensor 22y2, the magnetization direction of the free magnetic layer changes in accordance with the direction of the sensed magnetic field Hd, which is the resultant vector of the fixed magnetic field H1 and the movable magnetic field H2. The strength of the fixed magnetic field H1 is almost constant, and the strength of the movable magnetic field H2 changes as the movable magnetic field generating element 21y2 moves in the forward / backward direction (Z1-Z2 direction). Therefore, the angle θ of the vector of the sensed magnetic field Hd changes as the bobbin 6 moves in the forward / backward direction. By detecting the change in the electrical resistance value of the magnetoresistive element, the change in the angle θ of the sensed magnetic field Hd can be determined, and the change in the position of the movable magnetic field generating element 21y2 in the forward / backward direction can be determined.

[0035] The magnetic sensor is not limited to one that detects changes in the angle θ of the vector of the detection magnetic field Hd. For example, multiple magnetoresistance effect elements may be used to separately detect the strength of the fixed magnetic field H1 and the strength of the movable magnetic field H2, and the position of the bobbin 6 in the front-rear direction may be detected by detecting the ratio between the strength of the fixed magnetic field H1 and the strength of the movable magnetic field H2. Alternatively, the magnetic sensor may include two Hall elements. One Hall element has a directivity that can detect changes in magnetic field strength in a first direction (X direction), and the other Hall element has a directivity that can detect changes in magnetic field strength in a second direction (Y direction). These two Hall elements can detect the strength of the fixed magnetic field H1 facing the second direction and the strength of the movable magnetic field H2 facing the first direction, and the change in the position of the movable magnetic field generating element 21y2 in the front-rear direction can be detected from the ratio between the two intensities.

[0036] The configurations and detection operations of the magnetic sensors 22x1, 22x2, and 22y1 constituting the detection units 20x1, 20x2, and 21y1 provided at the other three locations are the same as those of the detection unit 20y2 shown in FIG.

[0037] As shown in FIGS. 1 and 2, a phase plug 28 is fixed to the front of the raising member 25 at the support portion.

[0038] Next, the sound generation operation of the speaker 1 will be described. In sound generation, a voice current is applied to the voice coil 7 based on an audio signal output from an audio amplifier. As the driving magnetic flux Fd emitted from the magnetic circuit unit 10 crosses the voice coil 7, the driving magnetic flux Fd and the voice current excite an electromagnetic force, causing the vibration unit including the bobbin 6 and diaphragm 3 to vibrate in the front-to-rear direction, generating sound pressure according to the frequency of the voice current and emitting sound forward (Z1 direction) or backward (Z2 direction).

[0039] A control unit (not shown) connected to speaker 1 performs feedback control based on the detection outputs from four magnetic sensors 22x1, 22x2, 22y1, and 22y2. By obtaining detection outputs based on the change in angle θ within the plane of the detected magnetic field Hd from each of magnetic sensors 22x1, 22x2, 22y1, and 22y2, or by obtaining the ratio between the intensity of fixed magnetic field H1 and the intensity of movable magnetic field H2, the control unit can determine the longitudinal position and change of the vibrating unit, including diaphragm 3. For example, the control unit calculates the deviation between the ideal longitudinal position and change of the vibrating unit estimated by applying a voice current and the actual position and change of the vibrating unit determined from the detection outputs of the magnetic sensors. If the deviation exceeds a threshold, a correction signal (offset signal) is generated to correct the deviation. The correction signal is superimposed on the voice current applied to voice coil 7. This feedback control corrects distortion and sound delays in the sound produced by speaker 1 and prevents excessive longitudinal vibration of diaphragm 3.

[0040] The feedback control can be performed by referring to at least one of the detection outputs obtained from the four magnetic sensors 22x1, 22x2, 22y1, and 22y2. However, the sound quality of the speaker 1 can be further improved by performing feedback control using all of the detection outputs obtained from the four magnetic sensors 22x1, 22x2, 22y1, and 22y2.

[0041] In parallel with the feedback control, the control unit monitors the detection outputs obtained from the four magnetic sensors 22x1, 22x2, 22y1, and 22y2, and determines whether any of the detection outputs is abnormal. This monitoring and determination may be performed continuously while the speaker 1 is operating, or may be performed periodically at intervals.

[0042] The front and rear positions of the vibrating unit can be detected using the detection outputs obtained from the four magnetic sensors 22x1, 22x2, 22y1, and 22y2, but if the amount of movement of the bobbin 6 determined by one of the detection outputs is extremely larger than the amount of movement determined by the other detection outputs, it can be determined that the vibrating unit may be damaged in a position close to the detection unit that showed the abnormal value. This phenomenon occurs when there is partial peeling at the joint between the diaphragm 3 and the edge member 4 or the joint between the edge member 4 and the front end peripheral portion 2a, or when there is partial peeling at the joint between the bobbin 6 and the damper member 5 or the joint between the damper member 5 and the inner peripheral fixed portion 2b.

[0043] When the amount of movement of the bobbin 6 determined by the detection output of any one of the four magnetic sensors 22x1, 22x2, 22y1, 22y2 is extremely smaller than the amount of movement determined by the other detection outputs, it can be determined that there is a possibility that a foreign object with a certain amount of mass is attached to the vibrating part at a position close to the detection part that showed the abnormal value. This phenomenon occurs when a foreign object is attached to any of the diaphragm 3, bobbin 6, edge member 4, or damper member 5.

[0044] If three or all of the detection outputs obtained from the four magnetic sensors 22x1, 22x2, 22y1, and 22y2 continue to be unrelated and unstable, it can be determined that the vibrating part may be rolling due to major damage to the vibrating part or the attachment of a large foreign object.

[0045] If the control unit determines that an abnormality has occurred during speaker 1 sound generation, it can stop supplying voice current to the voice coil 7 of the speaker 1, thereby informing the user that the speaker 1 is in a faulty state. Alternatively, the speaker 1 can emit a warning sound of a predetermined frequency. Furthermore, if the level of the abnormality is below a predetermined level, the signal in the low-frequency range of the voice current supplied to the voice coil 7, where the amplitude of the vibration section is large, can be cut or attenuated to continue sound generation. Furthermore, in an inspection process after the assembly process of the speaker 1, an inspection current can be applied to the voice coil 7 to determine whether there is an abnormality in the detection output from the four magnetic sensors 22x1, 22x2, 22y1, and 22y2. This inspection can detect assembly defects or component defects before shipping.

[0046] In the speaker 1 of the embodiment, each of the magnetic sensors 22x1, 22x2, 22y1, and 22y2 detects a change in the position of the vibrating unit based on the relative strength ratio between the fixed magnetic field H1 due to the leakage magnetic flux from the magnetic circuit unit 10 and the mobile magnetic field H2 due to the leakage magnetic flux from the mobile magnetic field generating elements 21x1, 21x2, 21y1, and 21y2. This makes it possible to perform highly accurate feedback control that is less susceptible to the influence of external noise, and also to detect with high accuracy whether or not there is an abnormality in any of the detection outputs without being affected by external noise.

[0047] As shown in FIG. 3, in the speaker 1, when viewed on a plane perpendicular to the center line O, the movable magnetic field generating elements 21x1, 21x2, 21y1, and 21y2 are arranged at 90-degree angles around the center line O. This prevents imbalance in the mass of the bobbin 6 on which the movable magnetic field generating devices are mounted, allowing the bobbin 6 to move forward and backward without being affected by imbalance in mass. Alternatively, the speaker 1 may be provided with only two detectors 20x1 and 20x2 arranged at 180-degree angles from the center line O, or only two detectors 20x1 and 20y1 arranged at 90-degree angles from the center line. In this case, it is preferable to fix a balancer to the bobbin 6, as necessary, to maintain a mass balance with the two movable magnetic field generating elements. Alternatively, detectors may be provided at three locations arranged at 120-degree angles from the center line O. However, if four detection units 20x1, 20x2, 20y1, and 20y2 are provided as in the speaker 1 of the above embodiment, the probability of detecting an abnormal operation of the vibration unit increases.

[0048] The detection unit provided in the speaker 1 of the present invention is not limited to one equipped with a magnetoresistive effect element that detects both the fixed magnetic field H1 and the movable magnetic field H2. For example, magnetic sensors or Hall elements may be provided at multiple locations on the support unit, and multiple movable magnetic field generating elements may be mounted on the vibrating unit, with each magnetic sensor or Hall element detecting only the intensity of the movable magnetic field H2.

[0049] Furthermore, the detection unit may be provided with speed sensors or acceleration sensors at multiple locations on the bobbin 6 or other vibrating parts to detect the forward and backward movement state at the locations where these sensors are located. Alternatively, optical sensors may be provided at multiple locations on the support part, and each optical sensor may be able to detect movement at a different position on the vibrating part. [Explanation of symbols]

[0050] 1 speaker 2 frames 3 Vibration plate 6 bobbins 7 Voice coil 10 Magnetic circuit part (fixed magnetic field generating member) 11 Drive magnet 12 opposing yoke 13 Rear yoke 14 Center York 20x1, 20x2, 20y1, 20y2 detection unit 21x1, 21x2, 21y1, 21y2 Moving magnetic field generating element 22x1, 22x2, 22y1, 22y2 magnetic sensors 25 Raising member 28 Phase Plug Fd driving magnetic flux H1 fixed magnetic field H2 moving magnetic field Hd detection magnetic field O center line

Claims

1. A speaker provided with a vibration section having a voice coil and a diaphragm that vibrates together with the voice coil, and a support section to which a magnetic circuit section that applies magnetic flux to the voice coil is fixed, a plurality of detectors for detecting the movement of the vibration unit are provided; the detection unit includes a moving magnetic field generating element provided on the vibration unit to generate a moving magnetic field, and a magnetic sensor provided on the support unit to detect the moving magnetic field, A speaker characterized in that, when viewed in a plane projected onto a plane perpendicular to a center line extending in the vibration direction of the vibration part, movement of different locations of the vibration part is detected by multiple detection parts.

2. 2. The speaker according to claim 1, wherein the detection unit detects movements at two locations that are spaced apart by an angle of 180 degrees from the center line when viewed on the plane.

3. 2. The speaker according to claim 1, wherein the detection unit detects movement at four locations positioned at 90 degrees around the center line when viewed on the plane.

4. 2. The speaker according to claim 1, wherein, when viewed in the plane, the centers of the magnetic sensors constituting each of the detection units and the centers of the movable magnetic field generating elements are positioned on the same line extending from the center line.

5. the detection unit has a fixed magnetic field generating member provided on the support unit, 5. A speaker according to claim 1, wherein the movable magnetic field generated by the movable magnetic field generating element and the fixed magnetic field generated by the fixed magnetic field generating member are detected by the magnetic sensor as magnetic field components in directions that intersect with each other.

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