Method and device for detecting displacement of a speaker

Abstract

To provide "a displacement detection calibration method of a speaker, a displacement detection device of a speaker, and a speaker unit" capable of accurately detecting a displacement.SOLUTION: A magnetic angle sensor 212 outputs: a component Vs in a Y direction where a vibration system of a synthetic vector of a magnetic vector of a magnetic circuit 220 of a speaker 2 and a magnetic vector of a displacement detection magnet 211 fixed on the vibration system of the speaker 2 is vibrated; and a component Vc of a X direction orthogonal to the Y direction. A test signal is applied to the speaker 2, a collection of (VS and VC) and a measurement of a Y-direction displacement of the vibration system by a displacement meter 72 are performed. A conversion formula: z=a1×Vs+a2×Vc for a first principle component z is obtained by principle component analysis on the collected (VS and VC), and a conversion formula: y=b1×z2+b2×z+b3 for conversion to the displacement y is obtained by polynomial regression on the Y-direction displacement y of the displacement detection magnet 211 obtained from a measurement value of the displacement meter 72 and the z calculated from the collected (VS and VC).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique for detecting the displacement of a vibration system of a speaker. [Background technology]

[0002] Known techniques for detecting the displacement of a vibration system of a speaker include a technique for detecting the displacement of the vibration system of a speaker by using a sensor attached to the speaker (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-228214 A [Patent Document 2] JP 2010-124026 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the above-mentioned technology of attaching a sensor to a speaker to detect the displacement of the speaker's diaphragm, there are cases where the displacement cannot be detected accurately because displacement detection errors occur depending on the individual degree of accuracy of attachment of the sensor to the speaker in terms of its position and orientation.

[0005] Therefore, an object of the present invention is to detect the displacement of the vibration system of a speaker with higher accuracy. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a speaker displacement detection calibration method for calibrating a conversion equation for converting (VS, VC) output by a sensor fixed to a non-vibration system of a speaker into a displacement of the vibration system, where Vs is a Y-direction component in which the vibration system vibrates, and Vc is an X-direction component perpendicular to the Y-direction, of a composite vector of a magnetic vector of a magnetic circuit of a speaker and a magnetic vector of a magnet fixed to a vibration system of the speaker, the conversion equation comprising the steps of applying a predetermined test signal to a speaker, collecting (VS, VC) output by the sensor, and measuring the displacement of the vibration meter in the Y-direction; The method includes the steps of: performing principal component analysis on the collected (VS, VC) to calculate a conversion equation from (VS, VC) to a first principal component z; assuming that the displacement of the magnet in the Y direction obtained from the measurement value of a displacement meter is y, performing polynomial regression on the relationship between y and z calculated from the collected (VS, VC) to calculate a conversion equation from z to displacement y; and setting an equation equivalent to an equation obtained by substituting the calculated conversion equation from (VS, VC) to the first principal component z into the calculated conversion equation from z to displacement y, as a conversion equation for converting the (VS, VC) output by the sensor into a displacement of the vibration system.

[0007] In order to achieve the above object, the present invention provides a speaker displacement detection calibration method for calibrating a conversion equation for converting (VS, VC) output by a sensor fixed to a non-vibration system of a speaker into a displacement of the vibration system, where Vs is the Y-direction component in which the vibration system vibrates, and Vc is the X-direction component perpendicular to the Y-direction, of the resultant vector of the magnetic vector of the magnetic circuit of the speaker and the magnetic vector of a magnet fixed to the vibration system of the speaker, the conversion equation being converted into a displacement of the vibration system, the method comprising the steps of applying a predetermined test signal to the speaker and collecting (VS, VC) output by the sensor, and performing principal component analysis on the collected (VS, VC). the displacement of the magnet in the Y direction when the test signal is applied, calculated using a model of the speaker, is set to y, and a polynomial regression is performed on the relationship between y and z calculated from the collected (VS, VC) to calculate a conversion equation from z to displacement y; and setting an equation equivalent to an equation obtained by substituting the calculated conversion equation from (VS, VC) to the first principal component z into the calculated conversion equation from z to displacement y, as a conversion equation for converting (VS, VC) output by the sensor into a displacement of the vibration system.

[0008] In the above displacement detection calibration method, the conversion formula from (VS, VC) to the first principal component z may be z=a1×Vs+a2×Vc, where a1 and a2 are values ​​obtained by principal component analysis, and the conversion formula from z to displacement y may be y=b1×z, where b1, b2, and b3 are values ​​obtained by polynomial regression. 2 +b2×z+b3.

[0009] In addition, the present invention provides a speaker displacement detection device for detecting the displacement of a speaker's vibration system, the device comprising: a magnet fixed to the vibration system of the speaker; a sensor fixed to a non-vibration system of the speaker, which outputs (VS, VC), where Vs is the Y-direction component in which the vibration system vibrates, and Vc is the X-direction component orthogonal to the Y-direction, of a resultant vector of the magnetic vector of the magnetic circuit of the speaker and the magnetic vector of the magnet; and a displacement calculation means for calculating the displacement of the speaker's non-vibration system in the Y-direction according to a conversion equation for converting (VS, VC) to z and converting z to y, which is the displacement of the magnet in the Y-direction, where z is the first principal component obtained by principal component analysis of (VS, VC).

[0010] The present invention also provides a speaker unit including such a speaker displacement detection device and the speaker, the speaker displacement detection device and the speaker being integrated together.

[0011] According to the displacement detection calibration method and the displacement detection device as described above, it is possible to calculate the first principal component z having a high contribution rate (the rate at which information is not lost by converting to one-dimensional form the first principal component z) regardless of the installation error of the magnet or sensor for each individual speaker, and therefore it is possible to set a conversion equation that converts the first principal component (VS, VC) into the displacement of the vibration system with high accuracy. Effect of the Invention

[0012] As described above, according to the present invention, the displacement of the vibration system of a speaker can be detected with higher accuracy. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing a configuration of an audio system according to an embodiment of the present invention. [Diagram 2] 1 is a diagram showing a configuration of a speaker according to an embodiment of the present invention; [Diagram 3] FIG. 11 is a diagram showing a configuration for calculating a displacement conversion equation according to an embodiment of the present invention. [Figure 4]FIG. 11 is a diagram showing a procedure for calculating a displacement conversion equation according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described. FIG. 1 shows the configuration of an audio system according to this embodiment. As shown in the figure, the acoustic system includes a control unit 1, a speaker 2, an audio device 3 that outputs an input signal Si which is an audio signal, a signal correction unit 4 that corrects the input signal Si and outputs an output signal So, an amplifier 5 for driving the speaker 2 which receives the output signal So as input, and a vibration measurement unit 6 that measures the vibration / displacement of the vibration system of the speaker 2.

[0015] FIG. 2a shows the configuration of the speaker 2. As shown in the figure, the speaker 2 includes a yoke 201 , a magnet 202 , a top plate 203 , a voice coil bobbin 204 , a voice coil 205 , a frame 206 , a damper 207 , a diaphragm 208 , an edge 209 , and a dust cap 210 .

[0016] With the top of the figure being the front of the front speaker and the bottom being the rear of the front speaker, yoke 201 has a protruding part 2011 protruding forward in the center, with an annular magnet 202 provided on the outer periphery of protruding part 2011, and an annular top plate 203 provided on magnet 202. Top plate 203 is made of a conductive material such as iron. A magnetic circuit 220 is formed by yoke 201, magnet 202, and top plate 203.

[0017] Voice coil bobbin 204 has a hollow cylindrical shape, and voice coil 205 to which a signal from amplifier 5 is applied is wound around the outer periphery. Furthermore, convex portion 2011 of yoke 201 is inserted into the hollow of voice coil bobbin 204 from the rear so that voice coil bobbin 204 can move back and forth with respect to yoke 201, and voice coil 205 is disposed at a position between convex portion 2011 of yoke 201 and top plate 203, where magnetic flux generated between the inner circumferential ends of top plate 203 by magnetic circuit 220 passes.

[0018] Diaphragm 208 has a shape similar to the side surface of a truncated cone whose height direction is the front-to-rear direction of the front speaker, and its outer circumferential end is connected to the front end of frame 206 by edge 209. In addition, the inner circumferential end of diaphragm 208 is fixed to the front end of voice coil bobbin 204.

[0019] In such a configuration of the speaker 2, when a signal is applied from the amplifier 5 to the voice coil 205, the voice coil bobbin 204 vibrates back and forth in accordance with the amplitude of the audio signal due to the electromagnetic interaction between the magnetism generated from the magnetic circuit 220 and the audio signal flowing through the voice coil 205. When the voice coil bobbin 204 vibrates, the diaphragm 208 connected to the voice coil bobbin 204 vibrates, and a sound corresponding to the signal from the amplifier 5 is generated.

[0020] Next, as shown in the figure, the axial direction of speaker 2 is the Y direction, and the radial direction is the X direction. A displacement detection magnet 211 and a magnetic angle sensor 212 are assembled to such speaker 2 in order to detect the displacement of diaphragm 208 in the Y direction.

[0021] The displacement detection magnet 211 is fixed to the voice coil bobbin 204 so as to move up and down together with the voice coil bobbin 204, and the magnetic angle sensor 212 is fixed to the top of the top plate 203 so as not to change its position relative to the magnetic circuit 220.

[0022] As shown in FIG. 2b, the magnetic angle sensor 212 detects the magnitude of the Y-direction component and the X-direction component of the resultant vector V of the magnetic vector generated by the magnetic circuit 220 and the magnetic vector generated by the displacement detection magnet 211, and outputs a Y detection value Vs indicating the magnitude of the Y-direction component and an X detection value Vc indicating the magnitude of the Y-direction component to the vibration measurement unit 6.

[0023] Here, the magnitude and direction of composite vector V of the magnetic vector generated by magnetic circuit 220 and the magnetic vector generated by the position detection magnet (combination of the magnitude of the Y-direction component and the magnitude of the X-direction component) changes according to the Y-direction displacement of displacement detection magnet 211 accompanying the displacement of voice coil bobbin 204, so the amount of displacement in the Y direction of the vibration system of speaker 2 can be calculated from Y detection value Vs and X detection value Vc.

[0024] Returning to FIG. 1, a displacement conversion formula for converting the Y detection value Vs and the X detection value Vc into the displacement amount in the Y direction of the vibration system of the speaker 2 is preset in the vibration measurement unit 6, as will be described in detail later. The vibration measuring unit 6 then substitutes the Y detection value Vs and the X detection value Vc output from the magnetic angle sensor 212 into the displacement conversion formula to calculate the amount of displacement in the Y direction of the vibration system of the speaker 2. Also, various vibration states of the vibration system of the speaker 2 are detected from the calculated amount of displacement.

[0025] The signal correction unit 4 refers to the vibration state of the vibration system of the speaker 2 measured by the vibration measurement unit 6, corrects the input signal Si with a transfer characteristic that cancels distortion of the output of the speaker 2 with respect to the input signal Si, and outputs the corrected signal to the amplifier 5 as an output signal So.

[0026] The control unit 1 comprehensively controls the operation of each unit in response to user operations and the external environment. The operation of setting the displacement conversion equation in the vibration measuring unit 6 in advance as described above will be described below. The displacement conversion formula is calculated using the configuration shown in FIG. As shown in the figure, this configuration includes a signal generator 71 that outputs a test signal such as a sine wave or a swept sine wave to a speaker 2 equipped with a displacement detection magnet 211 and a magnetic angle sensor 212, a displacement meter 72 that measures the Y-direction displacement of a vibration meter such as the diaphragm 208 of the speaker 2, and an analysis device 73.

[0027] Here, as the displacement meter 72, for example, a laser displacement meter or the like can be used. The analysis device 73 also includes a principal component analysis processing unit 731 and a polynomial regression processing unit 732 . The principal component analysis processing unit 731 collects a pair (Vs, Vc) of the Y detection value Vs and the X detection value Vc output by the magnetic angle sensor 212 in response to the test signal, and obtains the first principal component z(PCA1) by principal component analysis. That is, for example, as shown in Fig. 4a, when (Vs, Vc) shown by a black dot is collected, the first principal component z(PCA1) as shown in the figure is obtained.

[0028] z=a1×Vs+a2×Vc… (Formula 1) a1 and a2 are 2 +a2 2 Under the condition of =1, the variance of z calculated using equation 1 is maximized for the collected (Vs, Vc) using the Lagrange undetermined multiplier method or the like.

[0029] In this way, z in equation 1, from which a1 and a2 are calculated, becomes a one-dimensional representation of the two-dimensional (Vs, Vc) so that as little information as possible is lost. Here, Vs and Vc are originally two orthogonal components of one vector, so the contribution rate of the first principal component z calculated from the variance of z calculated by Equation 1 for the collected (Vs, Vc) (the rate at which information is not lost by linearizing to the first principal component z) is sufficiently high regardless of the installation error of the displacement detection magnet 211 and the magnetic angle sensor 212 for each individual of the speaker 2. And, because the contribution rate of the first principal component z is sufficiently high, the displacement amount in the Y direction of the vibration system of the speaker 2 can be calculated from z in almost the same way as when it is calculated from (Vs, Vc).

[0030] Next, the polynomial regression processing unit 732 generates data (y, z) by combining the distance y between the magnetic angle sensor 212 and the displacement detection magnet 211, which is determined from the displacement of the diaphragm 208 measured by the displacement meter 72 in response to the test signal, and z determined from the collected (Vs, Vc) using equation 1. The relationship between y and z combined as (y, z) is such that the time when the displacement meter 72 measures the displacement for which y was determined is the same as the time when the magnetic angle sensor 212 outputs (Vs, Vc) used to calculate z.

[0031] Then, polynomial regression is performed on the generated (y, z) data to obtain a quadratic polynomial of z that represents y. That is, for example, as shown in Figure 4b, when (y, z) indicated by a black dot is obtained, y=b1×z 2 +b2×z+b3 … (Equation 2) Request.

[0032] Here, the reason why Equation 2 is a quadratic polynomial is that the magnetic force of the displacement detection magnet 211 observed by the magnetic angle sensor 212 is inversely proportional to the square of the distance between the displacement detection magnet 211 and the magnetic angle sensor 212, and therefore the (y, z) data can be well regressed to a quadratic polynomial.

[0033] In polynomial regression, b1, b2, and b3 are determined, for example, by the least squares method as values ​​that minimize the root mean square error of the (y, z) data for Equation 2. Then, we substitute equation 1 for z1 in equation 2 to get equation 3. y=b1×(a1×Vs+a2×Vc) 2 +b2×(a1×Vs+a2×Vc)+b3 … (Equation 3) is set as a displacement conversion equation in the vibration measuring unit 6 of the acoustic system that uses the speaker 2 for which the above equation has been calculated.

[0034] The embodiment of the present invention has been described above. In the above embodiment, the displacement in the Y direction of the vibrometer of the speaker 2 is measured using the displacement meter 72. However, it is also possible to calculate the displacement in the Y direction of the vibrometer obtained in response to a test signal based on a model of the speaker 2 without using the displacement meter 72, and to use the calculated displacement in place of the displacement measured by the displacement meter 72.

[0035] In the above embodiment, the vibration measuring section 6 and the signal correcting section 4 may be integrated with the speaker 2 as a speaker unit. Moreover, the contribution rate of the first principal component z calculated as above and the root mean square error of the data (y, z) for Equation 2 can be used for evaluation such as judging manufacturing defects of individual speakers 2. Also, various characteristics of speaker 2, such as the zero point of speaker 2, can be estimated from the vibration state of the vibration system of speaker 2 represented by the displacement y calculated by Equation 3 for the test signal. [Explanation of symbols]

[0036] 1...control unit, 2...speaker, 3...audio device, 4...signal correction unit, 5...amplifier, 6...vibration measurement unit, 71...signal generator, 72...displacement meter, 73...analysis device, 201...yoke, 202...magnet, 203...top plate, 204...voice coil bobbin, 205...voice coil, 206...frame, 207...damper, 208...diaphragm, 209...edge, 210...dust cap, 211...displacement detection magnet, 212...magnetic angle sensor, 220...magnetic circuit, 731...principal component analysis processing unit, 732...polynomial regression processing unit, 2011...convex portion.

Claims

1. A speaker displacement detection calibration method, comprising the steps of: calibrating a conversion equation for converting (VS, VC) output by a sensor fixed to a non-vibration system of a speaker into a displacement of the vibration system, the conversion equation being calculated by: Vs being a Y-direction component in which the vibration system vibrates, and Vc being an X-direction component perpendicular to the Y-direction, of a resultant vector of a magnetic vector of a magnetic circuit of a speaker and a magnetic vector of a magnet fixed to a vibration system of the speaker; applying a predetermined test signal to a speaker, collecting (VS, VC) output by the sensor, and measuring the displacement of the vibration system in the Y direction; A step of performing a principal component analysis on the collected (VS, VC) to calculate a conversion formula from (VS, VC) to a first principal component z; A step of calculating a conversion equation from z to displacement y by performing polynomial regression on the relationship between y and z calculated from the collected (VS, VC), where y is the displacement of the magnet in the Y direction obtained from the measurement value of the displacement meter; setting an equation equivalent to an equation obtained by substituting the calculated conversion equation from (VS, VC) to the first principal component z into a conversion equation from the calculated z to the displacement y as a conversion equation for converting (VS, VC) output by the sensor into a displacement of the vibration system.

2. A speaker displacement detection calibration method, comprising the steps of: calibrating a conversion equation for converting (VS, VC) output by a sensor fixed to a non-vibration system of a speaker into a displacement of the vibration system, the conversion equation being calculated by: Vs being a Y-direction component in which the vibration system vibrates, and Vc being an X-direction component perpendicular to the Y-direction, of a resultant vector of a magnetic vector of a magnetic circuit of a speaker and a magnetic vector of a magnet fixed to a vibration system of the speaker; applying a predetermined test signal to a speaker and collecting the (VS, VC) output of the sensor; A step of performing a principal component analysis on the collected (VS, VC) to calculate a conversion formula from (VS, VC) to a first principal component z; A step of calculating a conversion equation from z to a displacement y by performing polynomial regression on the relationship between y and z calculated from the collected (VS, VC), where y is the displacement of the magnet in the Y direction when the test signal is applied, calculated using a model of the speaker; setting an equation equivalent to an equation obtained by substituting the calculated conversion equation from (VS, VC) to the first principal component z into a conversion equation from the calculated z to the displacement y as a conversion equation for converting (VS, VC) output by the sensor into a displacement of the vibration system.

3. 3. The displacement detection calibration method according to claim 1, further comprising the steps of: The conversion formula from (VS, VC) to the first principal component z is z = a1 × Vs + a2 × Vc, where a1 and a2 are the values ​​obtained by principal component analysis. The conversion formula from z to displacement y is y=b1×z, where b1, b2, and b3 are values ​​obtained by polynomial regression. 2 +b2×z+b3.

4. A speaker displacement detection device for detecting a displacement of a vibration system of a speaker, comprising: A magnet fixed to a vibration system of the speaker; a sensor fixed to the non-vibration system of the speaker, which outputs (VS, VC) where Vs is a component of a composite vector of the magnetic vector of the magnetic circuit of the speaker and the magnetic vector of the magnet in a Y direction in which the vibration system vibrates, and Vc is a component in an X direction perpendicular to the Y direction; a displacement calculation means for calculating a displacement in the Y direction of the vibration system of the speaker in accordance with a conversion equation for converting (VS, VC) to z, where z is a first principal component determined by a principal component analysis of (VS, VC), and converting z to y, which is the displacement of the magnet in the Y direction.

5. 5. A speaker unit comprising: the speaker displacement detection device according to claim 4; and the speaker, the speaker displacement detection device and the speaker being integrated together.

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