Calculation method and numerical calculation model data

Abstract

To reduce the computational load of sound pressure characteristics of a speaker system.SOLUTION: The calculation method is for calculating at least one of the vibration and sound pressures generated in an electromechanical system when a driving voltage is applied to an electromechanical energy converter of the electromechanical system of a speaker or an actuator that includes the electromechanical energy converter where the static electrical impedance is Ze, and includes: a first step of placing an equivalent mechanical element circuit in a virtual space including at least an electrical impedance equivalent mechanical element that is directly or indirectly connected to a point of application where a driving force generated in the electromechanical energy converter acts in a virtual space model, and which has properties mechanically equivalent to the electrical impedance Ze of the electromechanical energy converter; and a second step of setting a displacement velocity equivalent to the driving voltage applied to the electromechanical energy converter as a boundary condition to any end point of the equivalent mechanical element circuit or a node that is indirectly connected to the end point that functions as the end point.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to computational methods and numerical computational model data. [Background technology]

[0002] Patent Document 1 discloses a sound pressure characteristic calculation method that can accurately calculate the sound pressure characteristic of a speaker system without increasing the calculation scale or calculation time. The sound pressure characteristic calculation method includes a normalization step 1, a normalization step 2, a correction coefficient calculation step, and a sound pressure calculation step. In the normalization step 1, a relative vibration velocity difference, which is a velocity difference between the vibration velocity of a point of action on which a driving force generated by an electromechanical energy converter acts and the vibration velocity of a point of reaction on which a reaction force of the driving force acts, is normalized by the driving force to calculate normalized relative vibration velocity data. In the normalization step 2, normalized sound pressure data in which the sound pressure at the sound pressure observation point is normalized by the driving force is calculated. In the correction coefficient calculation step, a driving force correction coefficient for calculating the sound pressure at the sound pressure observation point is calculated from the normalized relative vibration velocity data, the electrical impedance value of the electromechanical energy converter, the force coefficient of the electromechanical energy converter, and a predetermined voltage. In the sound pressure calculation step, the sound pressure at the sound pressure observation point is calculated from the normalized sound pressure data and the driving force correction coefficient.

[0003] Non-Patent Document 1 discloses a method for analyzing the dynamic characteristics of a mechanical system expressed by a mechanical circuit by replacing it with an electric circuit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7113168 [Non-patent literature]

[0005] [Non-Patent Document 1] Makoto Shimojo, "Symbolic Analysis of Mechanical Circuits, August 2010 Edition", [online], University of Electro-Communications, [Accessed May 16, 2023], Internet<URL:http: / / www.rm.mce.uec.ac.jp / lecture / mech / MechCircuitMatrix.pdf> Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, as a method for calculating the reproduction sound pressure characteristics of a speaker system, a method is widely used in which a lumped constant equivalent circuit is created by replacing the Thiele and Small parameters (hereinafter referred to as "TS") parameters of a speaker unit and the acoustic structure or acoustic load of a housing with equivalent electric circuit components, and the sound pressure is calculated from a simulation of the circuit operation. Note that the object for calculating the sound pressure characteristics is not limited to a speaker system, but may be an electromechanical system including an electric circuit and a mechanical element such as an actuator.

[0007] In addition, there is a method of calculating sound pressure characteristics by coupling acoustic vibration analysis using Finite Element Method (hereinafter referred to as "FEM") analysis (finite element method analysis), which is effective for calculating sound pressure when the acoustic structure of the housing in which the speaker unit is mounted is complex or when deformation vibration of the structure cannot be ignored, with a lumped constant equivalent circuit using TS parameters.

[0008] In the sound pressure characteristic calculation method of Patent Document 1, when calculating the sound pressure characteristic of a speaker system, a large-scale FEM model of a mechanical acoustic system without an electrical model is first solved by assuming a constant excitation force, and a mechanical impedance is calculated. Next, the calculated mechanical impedance is used to calculate an excitation current value for constant voltage driving, and a sound pressure response to the excitation current value is calculated. However, this method requires two large-scale calculations to calculate the mechanical impedance and the sound pressure response, which results in a problem that the calculation takes a long time.

[0009] The present disclosure has been devised in view of the above-mentioned conventional situation, and aims to reduce the calculation load of vibration characteristics and sound pressure characteristics of an electromechanical system. [Means for solving the problem]

[0010] The present disclosure provides a calculation method for calculating at least one of vibration and sound pressure generated in an electromechanical system of a speaker or actuator including an electromechanical energy converter having a stationary electrical impedance Ze when a drive voltage is applied to the electromechanical energy converter, the calculation method including a first step of arranging in a virtual space an equivalent mechanical element circuit that is directly or indirectly connected to a point of application at which a drive force generated in the electromechanical energy converter of a model in a virtual space acts, and that includes at least a mechanical element having properties mechanically equivalent to the electrical impedance Ze of the electromechanical energy converter, and a second step of setting a displacement velocity equivalent to the drive voltage applied to the electromechanical energy converter as a boundary condition at any one of the end points of the equivalent mechanical element circuit or a node that is indirectly connected to the end point and serves as an end point.

[0011] The present disclosure also provides numerical calculation model data that at least describes the above calculation method, which defines the positional relationships and connection conditions of the mechanical elements of the equivalent mechanical element circuit, the boundary conditions of the displacement velocity, and the elements to which the boundary conditions of the displacement velocity are set.

[0012] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0013] According to the present disclosure, it is possible to reduce the calculation load of the vibration characteristics and sound pressure characteristics of an electromechanical system. [Brief description of the drawings]

[0014] [Figure 1] A block diagram of components of a computing device according to the present embodiment. [Diagram 2] FIG. 1 is a diagram showing an example of a speaker system according to an embodiment of the present invention; [Diagram 3] Diagram showing the operation model of the speaker unit [Figure 4] A flowchart showing an example of a conventional method for calculating the sound pressure characteristics of a speaker system. [Diagram 5] Diagram showing the operation model of the speaker unit [Figure 6] 1 is a flowchart showing an example of a method for calculating sound pressure characteristics of a speaker system according to an embodiment of the present invention. [Figure 7] FIG. 1 shows a modified example of an equivalent mechanical element circuit. [Figure 8] Diagram showing the definition of node names [Figure 9] An example of numerical calculation model data [Figure 10] An example of numerical calculation model data [Figure 11] A diagram showing an example of the calculation results of the sound pressure characteristics of a speaker system. [Figure 12] 3D distribution map of calculated sound pressure characteristics of a speaker system [Figure 13] FIG. 13 is a diagram showing a modified example of the operation model of the speaker unit according to the embodiment. [Figure 14] Diagram showing the structural model [Figure 15] Diagram showing the internal acoustic space [Figure 16] Diagram showing external acoustic space [Figure 17] FIG. 1 is a diagram showing a driving circuit for driving a plurality of speaker units in parallel. [Figure 18] A model diagram of an equivalent mechanical circuit replacing a parallel electrical circuit [Figure 19] A diagram showing an equivalent mechanical element circuit for calculating the sound pressure contribution of a speaker unit. [Figure 20] A diagram showing an equivalent mechanical element circuit for calculating the sound pressure contribution of a speaker unit. [Figure 21] Diagram showing the structural model [Figure 22] Diagram showing the internal acoustic space [Diagram 23] Diagram showing external acoustic space [Figure 24] A diagram showing the driving circuit for a two-way speaker including a network circuit. [Diagram 25] A model diagram in which the parallel network circuit and the speaker unit electrical circuit are replaced with an equivalent mechanical circuit. [Figure 26] A diagram showing an equivalent mechanical element circuit for calculating the sound pressure contribution of a tweeter unit. [Figure 27] A diagram showing an equivalent mechanical element circuit for calculating the sound pressure contribution of a speaker unit. [Figure 28] Diagram showing the definition of node names [Figure 29] An example of numerical calculation model data [Diagram 30] An example of numerical calculation model data [Diagram 31] Diagram showing the definition of node names [Diagram 32] An example of numerical calculation model data [Diagram 33] An example of numerical calculation model data [Diagram 34] An example of numerical calculation model data DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, with reference to the drawings as appropriate, an embodiment in which the calculation method and the numerical calculation model data according to the present disclosure are specifically disclosed will be described in detail. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters and duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the attached drawings and the following explanation are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0016] Fig. 1 illustrates components of a computing device 100 according to this embodiment. Fig. 1 is a block diagram of the components of the computing device 100 according to this embodiment.

[0017] The computing device 100 is a device that calculates the sound pressure characteristics of a speaker system 30 (see FIG. 2). Although a speaker is used as an example for explanation, the device is not limited to a speaker and may be an electromechanical system including an electric circuit such as an actuator and a mechanical element. The speaker system 30 is an acoustic body that is composed of a sealed housing 32 placed in a free space and a speaker unit 31 (see FIG. 2) that is placed at an arbitrary position of the sealed housing. Although a speaker is used as an example for explanation in this embodiment as a device for which sound pressure characteristics are to be calculated, the device is not limited to a speaker and may be an electromechanical system including an electric circuit such as an actuator and a mechanical element. The computing device 100 includes a processor 101, a communication I / F 102, a memory 103, and a display device 104.

[0018] The processor 101 is, for example, a central processing unit, a digital signal processor, a graphical processing unit, or a field programmable gate array. The processor 101 functions as a controller that manages the overall operation of the computing device 100. The processor 101 performs control processing for managing the operation of each part of the computing device 100, input / output processing of data between each part of the computing device 100, calculation processing of data, and storage processing of data. The processor 101 operates according to a program stored in the memory 103. The processor 101 uses the memory 103 during operation, and temporarily stores data generated or acquired by the processor 101 in the memory 103. The processor 101 performs at least one calculation processing of vibration and sound pressure characteristics of the speaker system 30.

[0019] The communication I / F 102 is an interface circuit that communicates wirelessly or wired with an external device (not shown). Here, I / F stands for interface. The external device is, for example, a device that can input parameters necessary for calculations. The communication method of the communication I / F 102 is, for example, mobile communication such as Wide Area Network, Local Area Network, Long Term Evolution, 4G, 5G, power line communication, short-distance wireless communication (e.g., Bluetooth (registered trademark) communication), or communication for mobile phones.

[0020] The memory 103 is configured using, for example, a Random Access Memory (hereinafter referred to as "RAM") and a Read Only Memory (hereinafter referred to as "ROM"), and temporarily stores programs necessary for the operation of the computing device 100, as well as data generated during the operation. The RAM is, for example, a work memory used during the operation of the computing device 100. The ROM stores and holds, for example, a program for controlling the computing device 100 in advance.

[0021] The display device 104 is a device that displays the results of calculations of the sound pressure characteristics of the speaker system 30 executed by the computing device 100. The display device 104 is, for example, a display or a touch panel display.

[0022] Next, an example of a speaker system 30 according to the present embodiment will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of a speaker system 30 according to the present embodiment.

[0023] Fig. 2(a) shows a vertical cross section of the speaker system 30. Fig. 2(b) shows a vertical cross section of the internal acoustic space 37 of the housing 32. Fig. 2(c) is an FEM model of the external acoustic space 39.

[0024] FEM model 324 is composed of structural model 520 discretized by element division using two-dimensional or three-dimensional structural elements for speaker unit 31 and housing 32, and spatial model 521 discretized by element division using three-dimensional spatial acoustic elements for internal acoustic space 37 and external acoustic space 39. Speaker unit 31 is composed of diaphragm 20 including a voice coil (not shown), and magnetic circuit 21 consisting of a magnet and a yoke (not shown).

[0025] The structural model 520 and the spatial model 521 are set as boundary conditions such that at least between the diaphragm 20 and the surface of the housing 32 on which the diaphragm 20 is placed, the air particle velocity of the spatial model 521 matches the surface normal velocity of the structural model 520, and the sound pressure of the spatial model 521 matches the surface pressure of the structural model 520.

[0026] In the space model 521, a sound absorbing surface 522 is defined on the outermost spherical surface part at a predetermined distance from the center of the housing 32 placed in the external acoustic space 39. A complex acoustic impedance of a spherical wave corresponding to the distance from the center of the space model 521 is set for the sound absorbing surface 522.

[0027] In addition, in the space model 521, a sound pressure observation point 23 is set at a position 1 m in front of the housing 32. The position of the sound pressure observation point 23 is not limited to 1 m in front of the housing 32 and can be set arbitrarily. The processor 101 outputs the sound pressure characteristics at the sound pressure observation point 23 as a calculation result.

[0028] In the structural model 520, at least one element or virtually connected point (for example, the center point 35 of the diaphragm) on the model of the voice coil or diaphragm becomes the excitation force application point. Also, in the structural model 520, one point on the magnet or the magnetic circuit 21 including the magnet (for example, the center point 34 of the magnetic circuit 21) becomes the application point of the reaction force of the excitation force. When the speaker unit 31 has an axisymmetric structure, the excitation force application point and the application point of the reaction force of the excitation force are preferably arranged on the axis of symmetry, for example, the center point 35 of the diaphragm and the center point 34 of the magnetic circuit. The center point 35, which is the excitation force application point, and the center point 34, which is the excitation force reaction point, are both set to have at least a degree of freedom of movement in the symmetric axis direction, and when the load condition is set, a predetermined vibration excitation force is set to the same magnitude in the opposite direction.

[0029] Although a model of a sealed housing 32 is used, the housing may include an acoustic element such as a bass reflex port or an acoustic horn in which the internal acoustic space 37 of the housing 32 and the external acoustic space 39 are connected by a spatial element. Also, the housing 32 may be set as a drone cone or the like if the same boundary conditions as those of the diaphragm are set. Also, for the sake of simplification, the modeling of the volume of the part corresponding to the magnetic circuit 21 and the magnetic gap near the voice coil (not shown) is omitted for the internal acoustic space 37 in this disclosure, but these may be included.

[0030] Next, an operation model of the speaker unit 31 will be described with reference to Fig. 3. Fig. 3 is a diagram showing an operation model of the speaker system 30, with the right side of the diagram being a structural model 520 and the left side being an electric circuit 111 including a drive circuit.

[0031] The speaker unit 31 includes electric elements and mechanical elements. The electric elements here are represented by a unit electric circuit 10 that models the state of electromechanical conversion of the speaker unit 31 using an equivalent circuit. The unit electric circuit 10 can be interpreted as an electromechanical energy converter, and converts between electric energy supplied or output between terminals 19 and 16, and mechanical energy supplied or output between terminals 17 and 18. The mechanical elements include a diaphragm 20 and a magnetic circuit 21. In the speaker unit 31, terminals 17 and 18, which are the output and input terminals for mechanical energy input / output of the unit electric circuit 10, are connected to the diaphragm 20 and the magnetic circuit 21.

[0032] The unit electric circuit 10 is represented by a circuit in which the voice coil DC resistance 13, the voice coil inductance 14, and the primary terminal of the electromechanical conversion virtual transformer 15 are connected to DC. The electromechanical conversion virtual transformer 15 is a virtual electronic element that represents the state of energy conversion between the electric elements and the mechanical elements of the speaker unit 31 as a transformer operation on an electric circuit. The end point 24 is grounded. A driving voltage is input to the terminal 11, and a driving current is supplied to the unit electric circuit 10 from the voltage amplifier 12 at a voltage proportional to the driving voltage of the terminal 11 regardless of the impedance fluctuation of the load. The terminal 18 is connected to the center of gravity 34 of the magnetic circuit 21, and the force applied in the direction of the arrow of the terminal 18 is equal to the force applied in the direction of the arrow of the center of gravity 34. The terminal 17 is connected to the center point 35 of the diaphragm 20, and the force applied in the direction of the arrow of the terminal 17 is equal to the force applied in the direction of the arrow of the center point 35. The terminal 18 and the center of gravity point 34, and the terminal 17 and the center point 35 may be directly connected to each other, or may be indirectly connected to each other by using a connecting member or the like therebetween.

[0033] A driving current flows through the voice coil due to the driving voltage input to terminal 11. When the voice coil is initially in a stationary state, the driving current is a value obtained by dividing the driving voltage by the electrical impedance Ze when diaphragm 20 is in a stationary state. The electrical impedance Ze is expressed by equation (1) using the DC resistance Re of the voice coil and the inductance Le of the voice coil.

[0034]

number

[0035] Here, j represents the current value and ω represents the angular frequency of the AC current.

[0036] A Lorentz force is generated in the voice coil by the driving current, and a reaction force is generated in the magnetic circuit 21 as a reaction. The Lorentz force generated in the voice coil excites the diaphragm 20, and a vibration velocity is generated in the diaphragm. If the reaction force generated in the magnetic circuit 21 is considered to act approximately on the center of gravity 34 of the magnetic circuit, the magnetic circuit 21 is excited and a vibration velocity is generated. Due to the vibration velocity generated in the voice coil and the diaphragm 20, acoustic radiation occurs on the front surface of the diaphragm (outside the housing 32). In addition, sound pressure is generated on the back surface of the diaphragm 20 (inside the housing 32), which excites the housing 32 and generates acoustic radiation from the housing 32. In addition, the vibration velocity generated in the magnetic circuit 21 propagates to the housing 32 and generates acoustic radiation to the outside of the housing 32. Furthermore, the vibration propagated to the housing 32 propagates from the back surface of the housing 32 into the internal space, generating internal sound pressure, which vibrates the diaphragm 20, and generates acoustic radiation from the diaphragm 20 to the front surface.

[0037] In this way, when a driving voltage is input to the unit electric circuit 10, a driving current determined by the electric impedance of the voice coil is generated at the beginning, and acts on the mechanical acoustic system of the diaphragm 20 and the magnet, which are mechanical elements, to vibrate the diaphragm 20 and the magnetic circuit 21. Next, as the mechanical acoustic system vibrates, an induced electromotive force is generated in the unit electric circuit 10 in the opposite direction to the driving voltage, and the induced electromotive force reduces the voltage effective for generating the Lorentz force. This voltage reduction causes the vibration velocity of the voice coil and the diaphragm to decrease in appearance. This is a phenomenon called electromagnetic damping, which must be taken into consideration when performing accurate sound pressure calculations of a speaker system. The reduction in the vibration velocity that occurs acts again from the mechanical acoustic system on the unit electric circuit, reducing the induced electromotive force, so this time the effective voltage increases. In this way, the unit electric circuit 10 and the mechanical acoustic system of the diaphragm 20 and the magnetic circuit 21 are in a non-causal interdependent relationship in which they affect each other without a time lag, and this interdependent relationship must be correctly expressed in order to analyze the sound pressure characteristics of the speaker system 30. One idea would be to use a model in which all components of the electrical circuit system and the mechanical acoustic system are discretized, and to analyze the sound pressure characteristics of speaker system 30 using a tightly coupled FEM analysis of all interdependent relationships; however, this would be difficult to implement in practice because the effort required to create the model or the calculation costs would be enormous.

[0038] Conventionally, there are several methods for analyzing the sound pressure characteristics of the speaker system 30. For example, there is a method in which the analysis of the electrical system of the electric circuit and the mechanical-acoustic system of the mechanical elements are alternately performed, and the results of each analysis are substituted into each other while performing calculations until the solution converges. With this method, the calculation load becomes enormous because a large-scale FEM analysis of the mechanical-acoustic system is repeatedly performed until the solution converges.

[0039] There is also a method to reduce the degrees of freedom of a large-scale FEM model of a mechanical acoustic system and integrate it into a one-dimensional model of an electric circuit for analysis. However, this method has problems in that errors occur when reducing a large-scale FEM model and that it is difficult to reduce a mechanical acoustic system.

[0040] There is also a method that, following the method disclosed in Patent Document 1, calculates the impedance of a mechanical-acoustic system (hereinafter referred to as "mechanical impedance") by assuming a constant excitation force for a large-scale FEM model of a mechanical-acoustic system, determines an excitation current value for constant voltage driving using the mechanical impedance, and calculates the sound pressure response by resetting the excitation force from the excitation current value. This method has the problem that large-scale calculations must be performed twice, to calculate the mechanical impedance and the excitation current value, making the calculation process complicated and time-consuming.

[0041] As described above, the conventional calculation methods have problems in determining the sound pressure characteristics of the speaker system 30, and there is still room for improvement.

[0042] Next, an example of a conventional method for calculating the sound pressure characteristics of the speaker system 30 (a method for determining the mechanical impedance and resetting the excitation force) will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of a conventional method for calculating the sound pressure characteristics of the speaker system 30.

[0043] The processor 101 creates FEM model data of the speaker system 30 (step St100). Specifically, the processor 101 sets components and connection methods of the diaphragm 20, the magnetic circuit 21, the internal acoustic space 37, the external acoustic space 39, and the housing 32, and creates an FEM model.

[0044] The processor 101 sets the point of application of the excitation force (hereinafter referred to as the "excitation force application point") and the sound pressure observation point 23 (see FIG. 2) (step St101). The excitation force application point is a point where the electromagnetic driving force generated in the unit electric circuit 10 acts on the mechanical system (for example, the center of gravity 34 and the central point 35 (see FIG. 3)).

[0045] The processor 101 sets the excitation force applied to the excitation force application point set in the process of step St101 as a mechanical impedance calculation step (step St102). Since the mechanical impedance is calculated as a ratio between the excitation force applied to the excitation point and the calculation result of the displacement speed of the excitation point, the excitation force is preferably set to a unit excitation force of 1 in order to omit division for calculating the ratio.

[0046] The processor 101 executes calculations under the excitation force conditions set in step St102, and calculates the excitation point displacement velocity corresponding to the mechanical impedance of the excitation force application point (step St103). The calculation method of the process in step St103 is a known method such as solving the equation of motion in the FEM model.

[0047] The processor 101 calculates the excitation force of the excitation force application point during constant voltage driving from the excitation point displacement speed calculated in step St103 as a sound field calculation step (step St104). The calculation method of the process in step St104 is a method using a known conversion formula disclosed in Patent Document 1.

[0048] The processor 101 resets the excitation force calculated in the process of step St104 to the excitation force application point (step St105).

[0049] The processor 101 executes calculations under the excitation force conditions set in step St105, and calculates the sound pressure at a predetermined point in the space model 521 including at least the sound pressure observation point 23 (step St106). The calculation method of the process in step St106 is the same as that in St103, except for the excitation force conditions given as boundary conditions.

[0050] The processor 101 displays the result of the calculation in the process of step St106 on the display device 104 (step St107).

[0051] Thus, in the conventional method of calculating the sound pressure characteristics of the speaker system 30, it is necessary to perform large-scale FEM calculations of the mechanical acoustic system twice (steps St103 and St106), which makes the calculation process complicated. In view of this situation, the present disclosure has sought a method of calculating the sound pressure characteristics of the speaker system 30 with simpler calculation processes. The new FEM calculation method according to the present disclosure will be described below.

[0052] Next, an operation model of the speaker unit 31 according to this embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram showing the operation model of the speaker unit 31, with the right side of the diagram being a structural model 520, and the left side being an equivalent mechanical element circuit 10A in which the unit electric circuit 10, which does not include a drive circuit, is replaced with a mechanical part. The equivalent mechanical element circuit is an element block that performs an operation dynamically equivalent to that of an electric circuit on an FEM model of a mechanical acoustic system, and is mainly one-dimensional mechanical elements such as springs, dampers, and concentrated masses that are spatially arranged in a circuit shape.

[0053] In this embodiment, the processor 101 creates an FEM model in which the unit electric circuit 10 shown in Fig. 3 is replaced with an equivalent mechanical element circuit 10A. It is known that the physical phenomena of mechanical systems and electric circuit systems have correlation and similarity, and analogy conversion is possible, and the conversion of the electric circuit system to the mechanical system is performed in accordance with the fi conversion rule based on a known theory (for example, Non-Patent Document 1, p. 37, Table 4.2, Force-Current Analogy Series).

[0054] The voice coil DC resistance 13 of the unit electric circuit 10 shown in Fig. 3 is replaced with a damper 44. Here, the mechanical resistance de of the damper is expressed as de=1 / Re using the DC resistance Re of the voice coil.

[0055] The voice coil inductance 14 of the unit electric circuit 10 shown in Fig. 3 is replaced with a spring 43. Here, the mechanical resistance ke of the spring is expressed as ke=1 / Le using the inductance Le of the voice coil.

[0056] The damper 44 and the spring 43 are directly or indirectly connected in series to form an electric impedance equivalent mechanical element. The electric impedance equivalent mechanical element is an element that performs mechanically equivalent operations to the electric impedance Ze in the electric circuit on the FEM model of the mechanical acoustic system.

[0057] The electromechanical conversion virtual transformer 15 of the unit electric circuit 10 shown in FIG. 3 is replaced by a scissors-shaped lever 46. The intermediate points 50 and 51 are the fulcrums of the lever 46, and a four-node link is formed between the end points 56 and 57 and between the driving force application end points 47 and 48, and the fulcrum connection parts of the intermediate points 50 and 51 are mechanism capable of parallel movement within a small displacement range. This makes it possible to express the insulation relationship between the primary side and the secondary side of the transformer as an electric circuit element by a mechanical model. As the operation of the lever 46, the ratio of the length between the intermediate point 50 and the end point 56, the driving force application end point 47 and the ratio of the length between the intermediate point 50 and the end point 56, the driving force application end point 47 are set to a force coefficient BL corresponding to the winding ratio of the electromechanical conversion virtual transformer 15. The couple force acting between end points 56, 57 on the left primary side is multiplied by BL between drive force application end points 47, 48 on the right secondary side, and the relative displacement and relative displacement speed between end points 56, 57 on the left primary side are multiplied by 1 / BL between drive force application end points 47, 48 on the right secondary side.

[0058] The spring 43, the damper 44, and the lever 46 are connected in series in accordance with the connection topology of the voice coil DC resistance 13, the voice coil inductance 14, and the electromechanical conversion virtual transformer 15 in FIG.

[0059] Connectors 42 and 58 indicate that the displacement in the direction perpendicular to the connection direction between spring 43 and damper 44 is constrained. In other words, connectors 42 and 58 are displaced only in the component parallel to the connection direction between spring 43 and damper 44. Connector 45 is constrained from displacement in the direction perpendicular to the connection direction between spring 43 and damper 44, and the component parallel to the connection direction is also constrained to an absolute displacement of 0 at ground terminal 49. As a result, the state in which terminal 16 of unit electric circuit 10 is electrically grounded is also expressed in equivalent mechanical element circuit 10A.

[0060] The driving force application end point 47 is connected to the center point 35. The force applied in the direction of the arrow of the driving force application end point 47 is equal to the force applied in the direction of the arrow of the center point 35, and the displacement and displacement speed of the driving force application end point 47 in the direction of the arrow are equal to the displacement and displacement speed of the center point 35 in the direction of the arrow. In addition, the driving force application end point 48 is connected to the center point 34. The force applied in the direction of the arrow of the driving force application end point 48 is equal to the force applied in the direction of the arrow of the center point 34, and the displacement and displacement speed of the driving force application end point 48 in the direction of the arrow are equal to the displacement and displacement speed of the center point 34 in the direction of the arrow. The driving force application end point 48 and the center point 34, and the driving force application end point 47 and the center point 35 may be directly connected, or may be indirectly connected by inserting a connecting member, a displacement constraint calculation formula element, or the like therebetween.

[0061] A forced displacement speed 60 corresponding to the drive voltage input to the terminal 19 of the unit electric circuit 10 (see FIG. 2) is input to the termination block 41.

[0062] As described above, the connector 58 is constrained so that only the component parallel to the connecting direction between the spring 43 and the damper 44 is displaced, but this displacement is constrained by the displacement constraint 59 installed on the terminal block 41 so that it is equal to the forced displacement speed 60. Due to this constraint, the state in which the circuit of the unit electric circuit 10 is driven at a constant voltage is also expressed in the equivalent mechanical element circuit 10A. Furthermore, when the forced displacement speed 60 input to the terminal block 41 is 0, the terminal block 41 is constrained to an absolute displacement of 0, similar to the ground terminal 49. Due to this operation, the state in which the terminal 19 and terminal 16 are short-circuited to ground in the circuit of the unit electric circuit 10 is also expressed in the equivalent mechanical element circuit 10A.

[0063] In this way, the unit electric circuit 10 (see FIG. 2) can be replaced with a machine element circuit including equivalent mechanical elements. A machine element circuit is a model of a virtual mechanical structure composed of mechanical elements.

[0064] In this embodiment, a moving coil type actuator is used as the electromechanical energy converter, and the voice coil is connected to a diaphragm that is a moving part. However, the electromechanical energy converter is not limited to this, and may be a moving magnet type in which a magnet is disposed on the main moving part side. Also, it may be an electromagnetic type in which a coil is wound around a magnet and a moving iron piece vibrates.

[0065] Next, an example of a method for calculating the sound pressure characteristics of the speaker system 30 according to the present embodiment will be described with reference to Fig. 6. Fig. 6 is a flowchart showing an example of a method for calculating the sound pressure characteristics of the speaker system 30 according to the present embodiment. Note that the same processes as those in the flowchart of Fig. 4 are denoted by the same reference numerals and will not be described.

[0066] The processor 101 sets an FEM model of a mechanical element equivalent to the electric circuit (step St202). That is, the processor 101 generates an equivalent mechanical element circuit 10A (see FIG. 5) that is mechanically equivalent to the unit electric circuit 10 (see FIG. 3) as an FEM model converted based on a known fi conversion law. The necessary elements are a damper 44 (see FIG. 5) that is a mechanical resistance equivalent to the voice coil DC resistance 13 (see FIG. 3), a spring 43 that is equivalent to the voice coil inductance 14 (see FIG. 3), and a scissors-shaped lever 46 (see FIG. 5) that is equivalent to the electromechanical conversion virtual transformer 15 (see FIG. 3) that represents the force coefficient BL of the electromechanical energy converter in the model of the unit electric circuit 10. The damper 44 and the spring 43 are connected in series in accordance with the circuit topology of the unit electric circuit 10 to generate a mechanical circuit equivalent to the electric impedance Ze of the unit electric circuit 10. Furthermore, one end of the primary circuit of a scissor-shaped lever 46 is connected in series to the damper 44 and spring 43, and one end of the series circuit of the primary circuit of the damper 44, spring 43, and scissor-shaped lever 46 is short-circuited and grounded. If the effect of the electromechanical conversion virtual transformer 15 (see FIG. 3) is converted by a magnification factor when converting the displacement speed due to the excitation force, the model using the lever 46 is unnecessary. In the case of a model that omits the lever, the element constants of the damper 44 and spring 43 are multiplied by the square of BL, similar to how the impedance of the primary circuit seen from the secondary side in an electric circuit is multiplied by the square of the turns ratio, and are expressed as de=BL·BL / Re and ke=BL·BL / Le.

[0067] If the frequency band in which the analysis is performed using the FEM model is a low frequency band and Le, which is the inductance component of the electric impedance Ze, can be ignored, the spring 43 of the electric impedance equivalent mechanical element equivalent to Le may be omitted. In other words, even in the simplest model, the electric impedance equivalent mechanical element includes the damper 44.

[0068] In addition, the connection order of the spring 43, the damper 44, and the lever 46 connected in series is not limited to the connection order in FIG. 5, and the terminal to be short-circuited and grounded is not limited to one end of the lever 46. The end to be short-circuited and grounded may be any terminal of the spring 43, the damper 44, and the lever 46, as long as it is one end of the elements connected in series. Here, a modified example of the equivalent mechanical element circuit will be described with reference to FIG. 7. FIG. 7 is a diagram showing a modified example of the equivalent mechanical element circuit. For example, in an equivalent mechanical element circuit 200 shown in FIG. 7(a), the spring 43, the damper 44, and the lever 46 are connected in series in the order of the spring 43, the lever 46, and the damper 44. In addition, in an equivalent mechanical element circuit 201 shown in FIG. 7(b), the spring 43, the damper 44, and the lever 46 are connected in series in the order of the lever 46, the damper 44, and the spring 43.

[0069] Next, the processor 101 connects the driving force application end point of the FEM model of the mechanical element equivalent to the electric circuit to the excitation force application point set in step St101 of the acoustic model creation step (step St203). That is, in the example shown in Fig. 5, the processor 101 connects the driving force application end point 47 of the secondary circuit of the scissors lever of the equivalent mechanical element circuit 10A to the center point 35, and the driving force application end point 48 of the secondary circuit to the center point 34. Note that, when the displacement of the reaction point of the excitation force can be ignored, that is, when the displacement of the magnetic circuit 21 is set to 0, the lever 46 becomes a ground type, and the lower half of the lever 46, the connector 45, and the ground terminal 49 can be omitted by constraining the intermediate point 50 to an absolute displacement of 0. Furthermore, in the case of a model in which the lever is omitted, the damper 44 and the spring 43 are directly arranged in series to the center point 35, and the center point 34 is directly short-circuited and grounded. In this manner, the processor 101 places, in the virtual space, an equivalent mechanical element circuit including at least an electrical impedance equivalent mechanical element having properties dynamically equivalent to the electrical impedance Ze of the electronic circuit in the processes of steps St202 and St203.

[0070] Next, the processor 101 defines an end point for inputting a displacement speed for vibrating the equivalent mechanical element circuit 10A (step St204). The processor 101 defines a terminal (for example, the terminal block 41 in FIG. 5) corresponding to the terminal 19 for supplying electric energy to the unit electric circuit 10 in the electric circuit 111, which is an end point on the primary side, i.e., the electric side, of the equivalent mechanical element circuit 10A, as an end point for inputting a displacement speed for vibrating the equivalent mechanical element circuit 10A. With this definition, the end point defined in the processing of step St204 is set as a boundary condition that the end point is short-circuited to ground when the displacement speed does not fluctuate. This boundary condition is the same as a boundary condition in which the output terminal of the voltage amplifier 12 in the electric circuit 111 is set to an internal resistance of 0 and is short-circuited to ground in passive AC operation. Note that the end point defined here may be the end point 57 on the lever side, and the processor 101 sets a value proportional to the drive voltage input to the terminal 19 of the unit electric circuit 10 as the displacement speed at the end point on the voltage application side. The proportionality constant is 1 when a scissors-type lever model is used. In a model that omits the effect of the electromechanical conversion virtual transformer 15 (see FIG. 3), the proportionality constant is set to the reciprocal of BL, which represents the force coefficient in the model of the unit electric circuit 10. The end point on the side other than the voltage application side is short-circuited to ground.

[0071] Next, the processor 101 sets the displacement speed equivalent to the drive voltage input to the terminal 19 of the unit electric circuit 10 to the end point defined in the process of step St204 (step St205). Here, in order to calculate the sound pressure frequency characteristic of the speaker system 30 for a predetermined sine wave voltage input, the processor 101 sets the excitation frequency and velocity amplitude of the excitation displacement speed that are equal in numerical value to the frequency and amplitude of the input sine wave voltage. In the processes of steps St204 and St205, the processor 101 sets the end point for inputting the excitation displacement speed and the displacement speed equivalent to the drive voltage input to the terminal 19 of the unit electric circuit 10.

[0072] The processor 101 calculates the sound pressure characteristic of the speaker system 30 using the FEM model set in the processes of steps St100, St101, St202, St203, St204, and St205 (step St206). The processor 101 calculates the mutual influence in the mechanical acoustic system including all of the mechanistic FEM model 523 consisting of the equivalent mechanical element circuit 10A and the structural model 520, and the spatial model 521 including the set boundary condition with the structural model 520, in a single strong coupling calculation. That is, the processor 101 calculates the sound pressure characteristic of the speaker system 30 in a single large-scale calculation.

[0073] The processor 101 displays the result of the calculation performed in step St206 on the display device 104 (step St107).

[0074] As described above, the calculation device 100 according to the present embodiment can calculate the sound pressure characteristic of the speaker system 30 in a single large-scale calculation by using an FEM model in which an electric circuit is replaced with an equivalent mechanical element circuit and integrated into a mechanical acoustic system. In other words, the calculation device 100 can reduce the number of times complicated large-scale calculations are performed without reducing the accuracy of the calculations, and can reduce the time required for calculation processing. Furthermore, the calculation device 100 can reduce the load on the processor 101 required for calculation processing.

[0075] Next, the numerical calculation model data describing the calculation method according to the present embodiment will be described with reference to Fig. 8, Fig. 9, and Fig. 10. Fig. 8 is a diagram showing the definition of the names of nodes. Fig. 9 and Fig. 10 are diagrams showing an example of the numerical calculation model data.

[0076] The names of each node are defined as shown in Fig. 8. The center point 35 is defined as "GRID101", the center of gravity point 34 as "GRID102", the driving force acting end point 47 as "GRID201", the driving force acting end point 48 as "GRID202", the midpoint 50 as "GRID203", the midpoint 51 as "GRID204", the connector 58 as "GRID211", the connector 42 as "GRID212" and "GRID213", and the connector 45 as "GRID214".

[0077] The numerical calculation model data DA1 and the numerical calculation model data DA2 are in a data format conforming to Nastran. The numerical calculation model data DA1 and the numerical calculation model data DA2 are an example of a data structure describing the calculation method according to the present embodiment shown in FIG. 6. The numerical calculation model data DA1 includes data D1, data D2, and data D3. The numerical calculation model data DA2 includes data D4, data D5, and data D6.

[0078] The data D1 is a data structure describing the processing contents stipulated in the acoustic model creation step (steps St100, St101) of the flowchart shown in Fig. 6. The data D1 defines the components and connection method of the diaphragm 20, the magnetic circuit 21, the internal acoustic space 37, the external acoustic space 39, and the housing 32, not shown, and defines the coordinates of GRID101 (i.e., the center point 35, which is the excitation point of the diaphragm 20) and GRID102 (i.e., the center of gravity point 34, which is the excitation point of the equivalent mechanical element circuit 10A) in addition to the set FEM model. The node definition line of the data D1 includes a node definition declaration, a node number, the X coordinate of the node, the Y coordinate of the node, and the Z coordinate of the node in the described order. For example, "GRID 101 -20.0 100.0 0.0".

[0079] Next, data D2 has a data structure describing the process contents of step St202 in the arrangement step of a mechanical element circuit equivalent to an electric circuit in the flowchart shown in FIG.

[0080] In data D2, the coordinates of each of GRID201, GRID202, GRID203, GRID204, GRID211, GRID212, GRID213, and GRID214 are defined as node definitions. Data D2 includes, in the stated order, a node definition declaration, a node number, the X coordinate of the node, the Y coordinate of the node, and the Z coordinate of the node.

[0081] In data D2, a damper 44, which is a virtual mechanical element, is defined. CDAMP2 defines the element of the damper 44. The damper definition line in CDAMP2 includes, in the order described, a damper definition declaration, a unique element identification number, the mechanical resistance of the damper, the node number of node 1, the component number in the displacement coordinate system that defines the displacement direction of node 1 specified in the CD entry of the GRID data, the node number of node 2, and the component number in the displacement coordinate system that defines the displacement direction of node 2 specified in the CD entry of the GRID data. Here, the CD entry represents the identification number of the coordinate system in which the displacement, the degree of freedom, the constraint condition, and the solution vector are defined at the node. In data D2, the CDAMP2 definition line defines that there is a damper 44 between GRID212 and GRID213, which is "CDAMP2 14 1.4706-4 212 1 213 1" and has a mechanical resistance of "1.4706-4 Ns / mm" that corresponds to an electrical resistance of 6.4 Ω. The mechanical resistance value of the damper 44 is input as ke=1 / Re.

[0082] In data D2, a spring 43, which is a virtual machine element, is defined. CELAS2 defines the element of spring 43. The spring definition line of CELAS2 includes, in the order described, a spring definition declaration, a unique element identification number, a spring constant, a node number of node 1, a component number in the displacement coordinate system that defines the displacement direction of node 1 specified in the CD entry of the GRID data, a node number of node 2, and a component number in the displacement coordinate system that defines the displacement direction of node 2 specified in the CD entry of the GRID data. In data D2, the CELAS2 definition line is "CELAS2 15 25.0 211 1 212 1", and defines that a spring 43 with a spring constant of "25N / mm" corresponding to an electric inductance of 0.04mH exists between GRID213 and GRID214. The spring constant of spring 43 is input as ke=1 / Le.

[0083] In data D2, a scissor-shaped lever 46 is defined. The MPC defines a constraint equation between multiple nodes constituting the lever 46. The definition line of the MPC includes a multi-point constraint declaration, a unique element identification number, a node number, a component number of the coordinates constrained by the MPC at the node, and a mobility factor of the node in the described order. The node number, component number, and mobility factor are described repeatedly for the number of nodes whose degrees of freedom are constrained by the MPC. In data D2, "MPC 21 201 1 4.29 203 1 -5.29 213 1 1.0" defines a constraint condition that limits the degrees of freedom so that the total displacement of 4.29 times the X displacement of GRID201, -5.29 times the X displacement of GRID203, and 1.0 times the X displacement of GRID213 is always 0. Due to this constraint, the relative displacement between GRID213 and GRID203 is constrained to 4.29 times the relative displacement between GRID201 and GRID203. In other words, when the displacement magnification of the lever is set as BL, the MPC defines a lever with BL=4.29, a fulcrum at midpoint 50, and including driving force application end point 47. In data D2, "MPC 22 202 1 4.29 204 1 -5.29 214 1 1.0" defines a constraint condition that restricts the degrees of freedom so that the total displacement of 4.29 times the X displacement of GRID202, -5.29 times the X displacement of GRID204, and 1.0 times the X displacement of GRID214 is always 0. Due to this constraint, the relative displacement between GRID214 and GRID204 is constrained to 4.29 times the relative displacement between GRID202 and GRID204. That is, when the displacement magnification of the lever is set as BL, the MPC defines a lever having BL=4.29, a fulcrum at midpoint 51, and including driving force application end point 48. In data D2, "MPC 23 203 1 1.0 204 1 -1.0" defines a constraint condition that restricts the degrees of freedom so that the total displacement of 1.0 times the X displacement of GRID 203 and -1.0 times the X displacement of GRID 204 is always 0. This constraint constrains the X displacements of GRID 203 and GRID 204 to always be equal. That is, the MPC defines the connected parallel movement of midpoint 50, which is the fulcrum of the right lever, and midpoint 51 of the left lever.

[0084] Next, data D3 is a data structure describing the processing contents of step St203 of the arrangement step of the mechanical element circuit equivalent to the electric circuit in the flowchart shown in Fig. 6. In data D3, "MPC 24 201 1 1.0 101 1 -1.0" defines that the driving force application end point 47 of the lever 46 and the center point 35, which is the excitation point of the diaphragm 20, are connected to share the X-direction degree of freedom. In data D3, "MPC 25 202 1 1.0 102 1 -1.0" defines that the driving force application end point 48 of the lever 46 and the center point 34, which is the excitation point of the structural model 520, are connected to each other.

[0085] As described above, the data D1, D2, and D3 define the positional relationships and connection conditions of the components of the equivalent mechanical element circuit.

[0086] Next, data D4 has a data structure describing the processing contents of step St204, which is the vibration displacement speed setting step in the flowchart shown in FIG.

[0087] Data D4 defines the end point for inputting the displacement velocity that excites the equivalent mechanical element circuit 10A. SPC defines the constraint condition of the degree of freedom of the node. SPC includes a single point constraint declaration, an identification number, a node number, a component number, and a forced displacement value in the described order. In data D4, "SPC 30 211 1 0.0" defines that the X degree of freedom of GRID 211 (i.e., the terminal block 41) is temporarily constrained to a displacement of 0. Also, "SPC 30 214 1 0.0" defines that the X degree of freedom of GRID 214 (i.e., the end point 57) is temporarily constrained to a displacement of 0. These end points correspond to terminals 19 and 16, which are input terminals in the corresponding unit electric circuit 10, and passively express that both terminals are in a grounded state. In this embodiment, terminal 16 is permanently grounded and terminal 19 is the constant voltage drive side, so a forced displacement constraint by SPCD is defined on GRID 211 (i.e., terminal block 41) which corresponds to terminal 19. The SPCD includes a forced drive declaration, an identification number, a node number, a component number, and a forced displacement amplitude magnification value in the order described. In data D4, "SPCD 31 211 1 1.0" defines that either a forced displacement velocity or a forced displacement acceleration is applied to GRID 211 (i.e., terminal block 41) at a value 1.0 times the set value.

[0088] Thus, data D4 defines the position where the boundary condition for the displacement speed is input.

[0089] Next, data D5 has a data structure describing the processing contents of step St205 of the vibration displacement speed setting step in the flowchart shown in FIG.

[0090] Data D5 defines a frequency table of the excitation force and the like.

[0091] RLOAD1 defines the type of contact load. RLOAD1 includes the values ​​of dynamic load declaration, identification number, amplitude definition identification number, initial time delay, initial phase, amplitude definition real part table identification number, amplitude definition imaginary part table identification number, and load type in the order described. In data D5, "RLOAD1 41 31 0 0 1 0 VELO" defines the forced displacement in the X direction set in GRID211 with identification number 31, i.e. SPCD31, as a nodal load with a load type of VELO, i.e. forced displacement velocity, with the initial time delay and initial phase both set to 0, and with reference to a table with a complex amplitude real part defined by identification number 1, i.e. TABLED1 1, described later, and an imaginary part of 0.

[0092] FREQ2 defines the frequency of the displacement velocity. FREQ2 includes the logarithmic interval frequency table declaration, identification number, start frequency, end frequency, and number of points, in the order described. In data D5, "FREQ2 13 10.0 100000.0 401" defines a frequency column vector of 401 points, logarithmically spaced, i.e., geometrically spaced, between RLOAD15 and 100 kHz.

[0093] TABLED1 defines a tabular function of displacement velocity. TABLED1 includes, in the order listed, a general table declaration, an identification number, a specification that the X-axis interpolation is either linear or logarithmic, and a specification that the Y-axis interpolation is either linear or logarithmic. TABLED1 also includes a line continuation flag, table value, and end flag in subsequent lines. In data D5, TABLED1 includes "TABLED1 1 LINEAR LINEAR" followed by "+ 0.0 2828.4 20000.0 2828.4 ENDT" in the subsequent line, which indicates that the X-axis interpolation and Y-axis interpolation are linear. Moreover, the values ​​shown under TABLE D1 are X1: 0.0 Y1: 2828.4 X2: 20000.0 Y2: 2828.4, and the value on the Y axis is the displacement velocity of 2828.4 mm / s equivalent to a constant applied voltage of 2.8284 V when an acoustic input equivalent to 1 W is injected into a speaker unit with a nominal impedance of 8 Ω.

[0094] Thus, data D5 defines the boundary conditions for the displacement velocity.

[0095] Next, data D6 has a data structure describing the process contents of step St206 of the calculation execution step in the flowchart shown in FIG.

[0096] Data D6 consolidates the boundary conditions and constraint conditions required for performing the calculation, and defines the method for performing the analytical calculation.

[0097] DLOAD defines the superposition of dynamic loads. DLOAD includes the following values ​​in the order of description: dynamic load superposition declaration, identification number, final scale, and a set of one or more RLOAD scales and RLOAD identification numbers. In data D5, "DLOAD 12 1.0 1.0 41" defines the load condition DLOAD12 in which the external force defined by identification number 41, i.e., RLOAD41, is multiplied by an individual scale of 1.0, superimposed with other RLOADs to form a single RLOAD, and further multiplied by an overall scale of 1.0. In this embodiment, only one RLOAD is superimposed, but there may be multiple RLOADs.

[0098] MPCADD unifies multi-point constrained MPCs. MPCADD includes the unification declaration, identification number, and the values ​​of multiple or single MPC identification numbers in the order described. In data D6, "MPCADD 20 21 22 23 24 25" unifies the multi-point constrained MPCs defined by identification numbers 21, 22, 23, 24, and 25, i.e., MPC21, 22, 23, 24, and 25, into one and defines it as MPCADD20.

[0099] SPCADD consolidates single-point constraint SPCs. SPCADD includes a consolidation declaration, an identification number, and a value of a plurality or a single SPC identification number in the order described. In data D6, "SPCADD 7 30 35" consolidates the single-point constraint SPCs defined by identification numbers 30 and 35, i.e., SPCs 30 and 35, into one and defines it as SPCADD7. In this embodiment, SPC35 includes SPCs defined in an SPC row (not shown) as constraint conditions that constrain all degrees of freedom other than the X-axis translation at all nodes included in the equivalent mechanical element circuit 10A, i.e., GRIDs 201, 202, 203, 204, 211, 212, 213, and 214.

[0100] ANALYSIS DFREQ defines that FEM analysis is to be performed using direct frequency response analysis. SPC= defines the unified single-point constraint condition to be used in the calculation, MPC= defines the unified multi-point constraint condition to be used in the calculation, FREQUENCY= defines the frequency table to calculate the frequency response, and DLOAD defines the load condition to be used in the calculation, each of which is defined by its identification number.

[0101] As described above, the numerical calculation model data DA1 and the numerical calculation model data DA2 describe the calculation method according to this embodiment shown in the flowchart of Fig. 6. By using the numerical calculation model data DA1 and the numerical calculation model data DA2, the processor 101 can analyze the sound pressure characteristics of the speaker system 30 with an FEM model in which an electric circuit is converted into an equivalent mechanical element circuit and integrated into one mechanical acoustic system. Note that the numerical values, data order, etc. of the numerical calculation model data DA1 and the numerical calculation model data DA2 are merely examples and are not limited to the example shown in Fig. 8.

[0102] Next, an example of the calculation result of the sound pressure characteristic of the speaker system 30 will be described with reference to Fig. 11 and Fig. 12. Fig. 11 is a diagram showing an example of the calculation result of the sound pressure characteristic of the speaker system 30. Fig. 12 is a three-dimensional distribution diagram of the calculated sound pressure characteristic of the speaker system 30.

[0103] Graph G1 shown in Fig. 11 has a horizontal axis representing frequency (Hz) and a vertical axis representing sound pressure (dB). Graph G1 represents sound pressure actually observed at sound pressure observation point 23 (Measurement) and sound pressure at sound pressure observation point 23 calculated by the calculation method according to the present embodiment (Prediction). It can be seen from graph G1 that Measurement and Prediction match with high accuracy. In other words, the calculation method according to the present embodiment can analyze the sound pressure characteristics of speaker system 30 with high accuracy.

[0104] 12 is a calculation result of the sound pressure distribution of the speaker system 30 calculated using the calculation method according to the present embodiment. The processor 101 displays the sound pressure distribution map G2 on the display device 104. This allows the calculation device 100 to display a distribution map of the calculated sound pressure characteristics of the external acoustic space 39 on the display device 104, thereby helping the user to visually recognize the calculation result in a three-dimensional manner.

[0105] Next, a modified example of the voice coil equivalent circuit model of the speaker unit 31 according to the present embodiment will be described with reference to Fig. 13. Fig. 13 is a diagram showing a modified example of the operation model of the speaker unit 31 according to the present embodiment.

[0106] The speaker unit 31 shown in Fig. 13 is a model that takes into account up to the second-order term of the electrical impedance in the electrical circuit. The equivalent mechanical element circuit 10B is a model that is composed of mechanical elements equivalent to the electrical circuit when up to the second-order term of the electrical impedance of the voice coil is taken into account. The same components as those in the equivalent mechanical element circuit 10A shown in Fig. 5 are denoted by the same reference numerals and will not be described.

[0107] In an electric circuit (not shown) equivalent to the equivalent mechanical element circuit 10B, the electric impedance Ze2 of the circuit is expressed by the formula (2).

[0108]

number

[0109] Here, the third term on the right side of equation (2) is a term of electrical impedance generated by eddy currents generated inside the conductors of the magnetic circuit 21 and the voice coil, and it is generally known that an electrical equivalent circuit is expressed as a parallel circuit of inductance L2 and electrical resistance R2. In the equivalent mechanical element circuit 10B, the third term on the right side of equation (2) is expressed as a parallel connection arrangement of the spring 52 and the damper 53, since the topology is preserved from the corresponding electric circuit (not shown). The spring 52 and the damper 53 connected in parallel are further connected in series to the spring 43. The resistance k2 of the spring 52 is k2=1 / L2. The mechanical resistance d2 of the damper 53 is d2=1 / R2. The connector 55 is displaced only in a direction parallel to the direction in which the spring 43 and the damper 44 are connected. The displacement speed for vibrating the equivalent mechanical element circuit 10B is input to the end point 54 from the terminal block 41, as in the equivalent mechanical element circuit 10A.

[0110] As described above, processor 101 can analyze the sound pressure characteristics of speaker system 30 in a single large-scale FEM analysis by generating an FEM model that converts an electric circuit into a mechanical element circuit equivalent to the electric circuit, even taking into account quadratic terms of the electric impedance of the electric circuit, and performing calculations.

[0111] <Modification> Next, a modified example of the FEM model 324 according to the present embodiment in which a plurality of speaker units are mounted on the housing will be described with reference to Figs. 14, 15, 16, 17, 18, 19, and 20. Figs. 14, 15, and 16 are diagrams showing an FEM model 624 which is a modified example of the FEM model 324 according to the present embodiment, and Fig. 14 is a diagram showing a structural model 620. Fig. 15 is a diagram showing an internal acoustic space 637. Fig. 16 is a diagram showing an external acoustic space 639. The internal acoustic space 637 and the external acoustic space 639 constitute a spatial model 621. Fig. 17 is a diagram showing a drive circuit for driving a plurality of speaker units in parallel.

[0112] 14 is an FEM structural model of a speaker system 630 in which speaker unit 31A and speaker unit 31B, which are the same as speaker unit 31, are mounted on top and bottom in a closed-type housing 632. The calculation device 100 sets, as a boundary condition for the structural model 620 and the spatial model 621, a condition that the air particle velocity of the spatial model 621 and the surface normal direction velocity of the structural model 620 coincide with each other between the diaphragms 20A and 20B and the surface of the housing 632 on which they are arranged, in the same manner as the structural model 520 and the spatial model 521. The calculation device 100 also sets, as a boundary condition for the structural model 620 and the spatial model 621, a condition that the sound pressure of the spatial model 621 and the surface pressure of the structural model 620 coincide with each other between the diaphragms 20A and 20B and the surface of the housing 632 on which they are arranged. With this setting, the two speaker units 31A and 31B are not only connected by the housing 632, but also form an FEM that is strongly coupled by the two parameters of the spatial model 621, that is, sound pressure and particle velocity.

[0113] In this modification, the two speaker units 31A and 31B are driven in parallel by the electric circuit of FIG. 17. The driving voltage and driving current supplied from the voltage amplifier 12 are supplied to the speaker unit 31A via the electric terminals 619A and 616A, and to the speaker unit 31B via the electric terminals 619B and 616B. FIG. 18 is a model diagram in which the electric circuits in parallel configuration are replaced with equivalent mechanical circuits. Here, the computing device 100 creates equivalent mechanical element circuits 610BA and 610BB (see FIG. 19 and FIG. 20) described later as equivalent mechanical element circuits for each unit. The computing device 100 temporarily deletes the terminal block 41A and the terminal block 41B at the driving end from the equivalent mechanical element circuit 610BA and the equivalent mechanical element circuit 610BB. Thereafter, the computing device 100 has a degree of freedom only in the input direction of the forced displacement velocity 660 (i.e., the horizontal direction of the screen) instead of the connectors 54A and 54B, and connects the equivalent mechanical element circuit 610BA and the equivalent mechanical element circuit 610BB using the connector 654. The computing device 100 places a terminal block 641 at the end after the connection, similar to the equivalent mechanical element circuit 10B (see FIG. 13) of the speaker unit 31. The terminal block 641 is constrained by a displacement constraint 659 so that the displacement velocity is equal to the forced displacement velocity 660. The computing device 100 connects the driving force application end point 47A on the secondary side of the scissors-shaped lever 46A to the center point 35A of the diaphragm of the speaker unit 31A, similar to the speaker unit 31 (see FIG. 5). The calculation device 100 also connects a driving force application end point 48A on the secondary side of the lever 46A to the center of gravity 34A of the magnet of the speaker unit 31A. The calculation device 100 also connects a driving force application end point 47B on the secondary side of the lever 46B to the center of gravity 35B of the diaphragm of the speaker unit 31B. The calculation device 100 also connects a driving force application end point 48B on the secondary side of the lever 46B to the center of gravity 34B of the magnet of the speaker unit 31B. The connectors 42A, 45A, 55A, 42B, 45B, and 55B, which are the other components, operate in the same manner as the connectors 42, 45, and 58, which are the components of the speaker unit 31 (see FIG. 5), and therefore a description thereof will be omitted.Moreover, the terminal points 56A, 57A, 56B, and 57B operate in the same manner as the terminal points 56 and 57 of the speaker unit 31 (see FIG. 5), and therefore their description will be omitted. The dampers 43A, 53A, 43B, and 53B operate in the same manner as the damper 44 of the speaker unit 31 (see FIG. 5), and therefore their description will be omitted. The springs 44A, 52A, 44B, and 52B operate in the same manner as the spring 43 of the speaker unit 31 (see FIG. 5), and therefore their description will be omitted. The levers 46A and 46B operate in the same manner as the lever 46 of the speaker unit 31 (see FIG. 5), and therefore their description will be omitted. The ground terminals 49A and 49B operate in the same manner as the ground terminal 49 of the speaker unit 31 (see FIG. 5), and therefore their description will be omitted. Note that the order in which the component elements are arranged in series is different between the equivalent mechanical element circuit 10B of the speaker unit 31 (see Figure 13) and the equivalent mechanical element circuit 610B of this modified example, but the order in which these elements are arranged in series may be the order exemplified in the equivalent mechanical element circuit 10B and the equivalent mechanical element circuit 610B or any other order, as long as they are arranged in series.

[0114] The calculation device 100 applies a forced displacement velocity 660 to the terminal block 641 using the equivalent mechanical element circuit 610B, the structural model 620, and the spatial model 621 while correctly reflecting the mutual influence between the units. That is, the calculation device 100 first arranges an end point (here, the terminal block 641 of the connector 654) that connects a plurality of nodes that are end points or indirectly connected to end points of the equivalent mechanical element circuits of the speaker unit 31A and the speaker unit 31B. After that, the calculation device 100 sets a forced displacement velocity 660 equivalent to the driving voltage supplied from the voltage amplifier 12 to the terminal block 641 that is an end point that connects a plurality of end points as a boundary condition. As a result, the calculation device 100 can calculate the total sound pressure of the sound reproduced by the speaker system having two units driven in parallel in one calculation.

[0115] Here, by further modifying the equivalent mechanical element circuit 610B, the calculation device 100 can separate the total sound pressure into the contributions of the speaker unit 31A and the speaker unit 31B and perform calculations. Fig. 19 is a diagram showing an equivalent mechanical element circuit for calculating the sound pressure contribution of the speaker unit 31A. Fig. 20 is a diagram showing an equivalent mechanical element circuit for calculating the sound pressure contribution of the speaker unit 31B.

[0116] When creating a model of a single unit being driven from a model of both units being driven, care must be taken when handling the electrical input terminal of the non-driven side. In terms of the physical phenomenon that occurs in the actual product, if you simply disconnect the drive connection of the non-driven side and leave it in an open state, and drive only the other side, the diaphragm of the non-driven side will vibrate due to pressure fluctuations in the cabinet and sound pressure propagation through the external acoustic space, and it will behave like a drone cone. In this drone cone operating state, even if you measure and add the sound pressure after swapping the driven side and non-driven side, it will not be the sound pressure of parallel driving. The reason this phenomenon occurs is that in a parallel driving state by a voltage amplification amplifier, regardless of the driving voltage, the output terminal of the amplifier, i.e. the input terminal of the speaker unit, is passively short-circuited in terms of AC, and electromagnetic damping works greatly, which cannot be reproduced by simply opening the connection.

[0117] Therefore, in the one-sided drive model of this modification, an equivalent mechanical element circuit is configured so that the electrical terminals of the non-driven side unit are short-circuited. Specifically, as shown in Figs. 19 and 20, the computing device 100 removes the connector 654 from the equivalent mechanical element circuit 610B, connects the connector 54A to the spring 44A, and connects the connector 54B to the spring 44B. The computing device 100 connects the terminal block 41A to the connector 54A and the terminal block 41B to the connector 54B, and arranges the equivalent mechanical element circuits 610BA and 610BB, which are equivalent mechanical element circuits of the speaker units 31A and 31B. The computing device 100 sets boundary conditions for the terminal block 41A and the terminal block 41B such that the displacement is constrained to a predetermined displacement speed by the displacement constraints 59A and 59B. The computing device 100 can configure a model that is passively short-circuited by the displacement constraints 59A and 59B. In Fig. 19, the calculation device 100 applies a forced displacement velocity 660A to the end block 41A connected to the speaker unit 31A, and the end block 41B sets or does not set the displacement velocity to 0 (zero), thereby calculating the sound pressure contribution degree of the speaker unit 31A. In Fig. 20, the calculation device 100 applies a forced displacement velocity 660B to the end block 41B connected to the speaker unit 31B, and the end block 41A sets or does not set the displacement velocity to 0 (zero), thereby calculating the sound pressure contribution degree of the speaker unit 31B. In other words, when the forced displacement velocity 660 corresponding to the drive voltage is set to the same value as the forced displacement velocity 660A and the forced displacement velocity 660B, the calculation device 100 calculates the sound pressure of the parallel drive model by superimposing the one-side drive one-side short-circuit model.

[0118] In this manner, first, the computing device 100 arranges the equivalent mechanical element circuit 610BA of the speaker unit 31A and the equivalent mechanical element circuit 610BB of the speaker unit 31B. The computing device 100 sets a boundary condition that is constrained to a predetermined displacement speed (in this modification, the forced displacement speed 660A, the forced displacement speed 660B) at all nodes (in this modification, the terminal block 41A, the terminal block 41B) that are either end points of the respective equivalent mechanical element circuits or end points indirectly connected to the end points. The boundary condition set here is such that a predetermined displacement speed (in this modification, the forced displacement speed 660A, the forced displacement speed 660B) that is not zero is set at either end point of one of the equivalent mechanical element circuits (in this modification, the equivalent mechanical element circuit 610BA, the equivalent mechanical element circuit 610BB), and the displacement speeds input to the end points or nodes of the other equivalent mechanical element circuits are set to 0 (zero).

[0119] As a result, the calculation device 100 can calculate the sound pressure contribution of one speaker unit to a speaker system including multiple speaker units. Conventionally, when calculating the sound pressure of a complex speaker system including multiple speaker units, there is a problem that the calculation of the mutual influence between the multiple speaker units is particularly complicated, and the analysis takes time or is difficult. However, the calculation device 100 can easily calculate the sound pressure even in a complex speaker system by configuring an equivalent mechanical element circuit so that the electric terminal of the non-driven side unit is short-circuited in the speaker system including multiple speaker units, accurately calculating the sound pressure contribution of each speaker unit, and calculating the total sound pressure using the principle of superposition. In addition, the calculation device 100 can accurately calculate the sound pressure contribution of each speaker unit in a speaker system including multiple speaker units, so that the user can be supported in changing the design of the speaker system so that the total sound pressure becomes a desired sound pressure based on the sound pressure contribution of each speaker unit. In this embodiment, the procedure for separating the mutual influences of multiple electromechanical energy converters has been described using an example of calculating the sound pressure transfer function of a speaker, but the present disclosure is not limited to such an example. For example, the procedure disclosed herein can also be used as a procedure for separating mechanical vibrations at a predetermined position on a mechanical device, which is excited by the mechanical device on which multiple voice coil actuators are arranged, into vibration contributions of each actuator as a transfer function.

[0120] Next, referring to Figs. 21, 22, 23, 24, 25, 26, and 27, a modified example of a two-way speaker system modeled with a plurality of speaker units connected by a network circuit in the FEM model 324 according to the present embodiment will be described. Figs. 21, 22, and 23 are diagrams showing an FEM model 724 which is a modified example of the FEM model 324 according to the present embodiment. Fig. 21 is a diagram showing a structural model 720. Fig. 22 is a diagram showing an internal acoustic space 737. Fig. 23 is a diagram showing an external acoustic space 739. The internal acoustic space 737 and the external acoustic space 739 constitute a space model 721. Fig. 24 is a diagram showing a driving circuit for a two-way speaker including a network circuit.

[0121] The structural model 720 shown in FIG. 21 is an FEM structural model of a speaker system 730 in which a speaker unit 31B, which is the same as the speaker unit 31 (see FIG. 5), is arranged as a woofer in a lower stage in a closed-type housing 732, and a tweeter unit 31C for reproducing high-pitched sounds is arranged in an upper stage. The calculation device 100 sets, as a boundary condition for the structural model 720 and the spatial model 621, a condition that the air particle velocity of the spatial model 721 and the surface normal direction velocity of the structural model 720 coincide with each other between the diaphragms 20C and 20B and the surface of the housing 732 on which they are arranged, in the same manner as the structural model 520 and the spatial model 521. The calculation device 100 also sets, as a boundary condition for the structural model 720 and the spatial model 621, a condition that the sound pressure of the spatial model 721 and the surface pressure of the structural model 720 coincide with each other between the diaphragms 20C and 20B and the surface of the housing 732 on which they are arranged. With this setting, the two tweeter units 31C and the speaker unit 31B are not only connected by the housing 732, but also form an FEM that is strongly coupled by two parameters, sound pressure and particle velocity, which are parameters of the spatial model 721. However, in this modified example, the back space of the tweeter unit does not communicate with the internal acoustic space 737 of the cabinet, and the coupling between units by the spatial model is a model that is limited to coupling on the diaphragm surface.

[0122] In this modification, the two tweeter units 31C and the speaker unit 31B are driven in parallel by the electric circuit of FIG. 24. The dividing network circuit 790 is an electric circuit including the tweeter unit 31C and the speaker unit 31B. The driving voltage and driving current supplied from the voltage amplifier 12 are supplied to the tweeter unit 31C through the electric terminals 719C and 716C via a high-pass filter composed of a high-pass filter capacitor 704 and a high-pass filter coil 703. The driving voltage and driving current supplied from the voltage amplifier 12 are supplied to the speaker unit 31B through the electric terminals 719B and 716B via a low-pass filter composed of a low-pass filter capacitor 701 and a low-pass filter coil 702. FIG. 25 is a model diagram in which the parallel network circuit and the speaker unit electric circuit are replaced with an equivalent mechanical circuit. Here, the computing device 100 creates, as an equivalent mechanical element circuit for each unit, an equivalent mechanical element circuit 610BA and a tweeter equivalent mechanical element circuit with the same configuration as the equivalent mechanical element circuit 610BB (see Figs. 19 and 20) in which the parameters of each element are replaced with the parameters of the tweeter unit 31C. The computing device 100 temporarily deletes the low-pass filter termination block 741B at the driving end and the high-pass filter termination block 741C at the driving end of the tweeter equivalent mechanical element circuit from the equivalent mechanical element circuit 710BC and the equivalent mechanical element circuit 710BB. After that, the computing device 100 additionally places components equivalent to the network circuit in Fig. 24.

[0123] As components equivalent to a network circuit, the computing device 100 places a low-pass filter relative acceleration proportional mass 701M corresponding to the low-pass filter capacitor 701 and a low-pass filter coil equivalent spring 702M corresponding to the low-pass filter coil 702, which are low-pass filter components for the woofer, in an equivalent mechanical element circuit connected to the speaker unit 31B. Also, as components equivalent to a network circuit, the computing device 100 places a high-pass filter coil equivalent spring 703M corresponding to the high-pass filter coil 703 and a high-pass filter relative acceleration proportional mass 704M corresponding to the high-pass filter capacitor 704, which are high-pass filter components for the woofer, in an equivalent mechanical element circuit connected to the tweeter unit 31C.

[0124] The computing device 100 connects the arranged components so as to preserve and trace the circuit topology of FIG. 24. The low-pass filter relative acceleration proportional mass 701M has one end mechanically grounded to the displacement constraint 759B via a connector 753B, and the other end connected to a connector 754B at the driving end of the speaker unit 31B. The high-pass filter coil equivalent spring 703M has one end connected to a connector 754B, and the other end connected to a connector 754 that connects the woofer circuit and the tweeter circuit. The tweeter side high-pass filter coil equivalent spring 703M has one end mechanically grounded to the displacement constraint 759C via a connector 753C, and the other end connected to a connector 754C at the driving end of the tweeter unit 31C. One end of high-pass filter relative acceleration proportional mass 704M is connected to connector 754C, and the other end is connected to connector 754 which connects the woofer circuit and the tweeter circuit. Connector 754 has a driving end connected to termination block 741, similar to connector 654, and is constrained by displacement constraint 759 so that the displacement speed is equal to forced displacement speed 760.

[0125] The computing device 100 connects the driving force acting end point 47C on the secondary side of the tweeter's scissors-shaped lever 46C to the center point 35C of the diaphragm of the tweeter unit 31C, as in the case of the speaker unit 31. The computing device 100 also connects the driving force acting end point 48C on the secondary side of the tweeter's scissors-shaped lever 46C to the center of gravity point 34C of the magnet of the tweeter unit 31C. As other components of the tweeter, the connectors 42C, 45C, and 55C operate in the same manner as the connectors 42, 45, and 58 that are components of the speaker unit 31 (see FIG. 5), and therefore a description thereof will be omitted. Furthermore, the dampers 43C and 53C operate in the same manner as the damper 44 that is a component of the speaker unit 31 (see FIG. 5), and therefore a description thereof will be omitted. The springs 44C and 52C operate in the same manner as the spring 43 of the speaker unit 31 (see FIG. 5), and therefore their description will be omitted. The lever 46C operates in the same manner as the lever 46 of the speaker unit 31 (see FIG. 5), and therefore their description will be omitted. The ground terminals 49C, 739C, and 739B operate in the same manner as the ground terminal 49 of the speaker unit 31 (see FIG. 5), and therefore their description will be omitted. The terminals 56C and 57C operate in the same manner as the terminals 56 and 57 of the speaker unit 31 (see FIG. 5), and therefore their description will be omitted. Note that the equivalent mechanical element circuit 10B of the speaker unit 31 and the equivalent mechanical element circuit 710B of this modification are arranged in series and have different arrangement orders of the component elements, but the arrangement order of these elements may be the arrangement order exemplified in the equivalent mechanical element circuit 10B and the equivalent mechanical element circuit 610B or any other arrangement order as long as they are arranged in series.

[0126] The computing device 100 uses the equivalent mechanical element circuit 710B, the structural model 720, and the spatial model 721 to apply a forced displacement velocity 760 to the terminal block 741 while correctly reflecting the mutual influence between the units. This allows the computing device 100 to calculate, in a single calculation, the total sound pressure of the reproduced sound of a two-way speaker system equipped with a plurality of speaker units connected by a network circuit.

[0127] Here, by further modifying the equivalent mechanical element circuit 710B, the calculation device 100 can separate the total sound pressure into the contributions of the tweeter unit 31C and the speaker unit 31B and perform calculations. Fig. 26 is a diagram showing an equivalent mechanical element circuit for calculating the sound pressure contribution of the tweeter unit 31C. Fig. 27 is a diagram showing an equivalent mechanical element circuit for calculating the sound pressure contribution of the speaker unit 31B.

[0128] When creating a model of a single unit being driven from a model of a multiple unit being driven including a network circuit, care must be taken when handling the electrical input terminal of the non-driven side, just as with the parallel drive. In particular, since the electrical terminal short-circuit point, which corresponds to the constant voltage drive boundary condition, is the drive point position of the network circuit, a model that reproduces the operation of a single unit requires modeling in which the filter circuits of each network circuit are added to the equivalent mechanical element circuit of each unit.

[0129] Therefore, in the model in which the tweeter and the woofer are driven independently in this modification, the equivalent mechanical element circuit is configured so that the filter circuit input electric terminal of the non-driven unit is in a short-circuit state. Specifically, as shown in Figs. 26 and 27, the calculation device 100 removes the connector 754 from the equivalent mechanical element circuit 710B, connects the connector 742 to the relative acceleration proportional mass 704M for the high-pass filter, and connects the connector 743 to the coil equivalent spring 702M for the low-pass filter. The calculation device 100 arranges the equivalent mechanical element circuit 710BC of the high-pass filter and the tweeter unit 31C by adding the high-pass filter terminal block 741C to the equivalent mechanical element circuit in the upper stage. The calculation device 100 arranges the equivalent mechanical element circuit 710BB of the low-pass filter and the speaker unit 31B by adding the low-pass filter terminal block 741B to the equivalent mechanical element circuit in the lower stage. The calculation device 100 sets boundary conditions in which the displacement is constrained to a predetermined displacement velocity by the displacement constraint 759C and the displacement constraint 759B for the high-pass filter terminal block 741C and the low-pass filter terminal block 741B. A model in which the displacement is passively short-circuited can be configured by the displacement constraints 759C and 759B. In FIG. 26, the calculation device 100 applies a forced displacement velocity 760C to the high-pass filter terminal block 741C connected to the tweeter unit 31C, and the low-pass filter terminal block 741B sets or does not set the displacement velocity to 0 (zero), thereby calculating the sound pressure contribution of the tweeter unit 31C. In FIG. 27, the calculation device 100 applies a forced displacement velocity 760B to the low-pass filter terminal block 741B connected to the speaker unit 31B, and the high-pass filter terminal block 741C sets or does not set the displacement velocity to 0 (zero), thereby calculating the sound pressure contribution of the speaker unit 31B. In other words, by setting the forced displacement velocity 760 corresponding to the drive voltage to the same values ​​as the forced displacement velocity 760C and the forced displacement velocity 760B, the calculation device 100 calculates the sound pressure of the two-way speaker system model by superimposing a model of the tweeter driven, woofer short-circuited state and a model of the tweeter short-circuited, woofer driven state.

[0130] Next, the numerical calculation model data describing the calculation method according to the modified example will be described with reference to Fig. 28, Fig. 29, Fig. 30, Fig. 31, Fig. 32, Fig. 33, and Fig. 34. Fig. 28 and Fig. 31 are diagrams showing the definition of the node names. Fig. 29, Fig. 30, Fig. 32, Fig. 33, and Fig. 34 are diagrams showing an example of the numerical calculation model data. Note that the description of the same data structure as Fig. 9 and Fig. 10 will be omitted.

[0131] As shown in FIG. 28, the names of the nodes are defined. In the modified example, only the necessary nodes are defined here because the difference from the numerical calculation model data shown in FIG. 9 and FIG. 10 will be described. The displacement constraint 759 is defined to be "GRID641", the connection point of the high-pass filter relative acceleration proportional mass 704M in the connector 754 is defined to be "GRID1644", the low-pass filter coil equivalent spring 702M in the connector 754 is defined to be "GRID2644", the low-pass filter relative acceleration proportional mass 701M is defined to be "GRID701", the ground terminal 739B is defined to be "GRID702", the ground terminal 49C is defined to be "GRID1649", and the ground terminal 49B is defined to be "GRID2649". The horizontal displacement in the direction of the forced displacement velocity 760 in FIG. 25 is defined to be the X-axis, and the axis perpendicular to the X-axis in the two-dimensional plane of the equivalent mechanical element circuit 710B is defined to be the Y-axis. These directional expressions are used for the convenience of explanation and are not intended to limit the orientation of the structure during actual use.

[0132] The numerical calculation model data DA3, DA4, DA5, DA6, and DA7 are in a data format that complies with Nastran.

[0133] The numerical calculation model data DA3 is model data corresponding to the equivalent mechanical element circuit 710B shown in Fig. 25. The numerical calculation model data DA3 includes data D7A.

[0134] Data D7A is a data structure describing the processing content of step St202 of the placement step of a mechanical element circuit equivalent to an electric circuit in the flowchart shown in Fig. 6. Data D7A defines the coordinates of each of GRID1644, GRID1649, GRID641, GRID2644, and GRID2649 as the definition of a node. Data D7A also defines that the degree of freedom is shared by the connector 754 (see Fig. 25) as "3-point X-displacement sharing" so that the three end points (nodes 641, 1644, 2644) have the same X-displacement.

[0135] The numerical calculation model data DA4 is model data corresponding to the equivalent mechanical element circuit 710B shown in Fig. 25. The numerical calculation model data DA4 includes data D8A, D9A, and D10A.

[0136] The data D8A has a data structure describing the processing contents of step St204 of the vibration displacement speed setting step in the flowchart shown in FIG.

[0137] The data D8A defines an end point for inputting a displacement speed for exciting the equivalent mechanical element circuit 710B. In the data D8A, "SPC 30 1649 1 0.0" defines that the X degree of freedom of GRID1649 (i.e., the ground terminal 49C) is temporarily constrained to a displacement of 0 (zero). In the data D8A, "SPC 30 2649 1 0.0" defines that the X degree of freedom of GRID2649 (i.e., the ground terminal 49B) is temporarily constrained to a displacement of 0 (zero). In the data D8A, "SPC 30 641 1 0.0" defines that the X degree of freedom of GRID641 (i.e., the displacement constraint 759) is temporarily constrained to a displacement of 0 (zero). In this modification, a forced displacement constraint is defined by SPCD on the GRID641 (i.e., the displacement constraint 759) side. In data D8A, "SPCD 631 641 1 1.0" defines that either the enforced displacement velocity or the enforced displacement acceleration is applied to GRID 641 (i.e., the displacement constraint 759) at a value 1.0 times the set value. Thus, data D8A defines the position where the boundary condition for the displacement velocity is input.

[0138] Next, data D9A has a data structure describing the processing contents of step St205 of the vibration displacement speed setting step in the flowchart shown in FIG.

[0139] In data D9A, "RLOAD1 6641 631 0 0 1 VELO" defines a forced displacement in the X direction set in GRID 641 with identification number 631, i.e., SPCD 631. RLOAD1 defines a forced displacement in the X direction set in GRID 641 as a nodal load whose load type is VELO, i.e., forced displacement velocity, referencing a table in which the real part of the complex amplitude is defined by identification number 1, i.e., TABLED1 1, shown in FIG. 10, and the imaginary part is 0, with both the initial time delay and initial phase at 0 (zero). As described above, data D9A defines the boundary condition for the displacement velocity.

[0140] Next, data D10A has a data structure describing the process contents of step St206 of the calculation execution step in the flowchart shown in FIG.

[0141] The data D10A consolidates the boundary conditions and constraint conditions required for performing the calculation, and defines a method for performing the analytical calculation.

[0142] In data D10A, "DLOAD 612 1.0 1.0 6641" multiplies the external force defined by identification number 6641, i.e., RLOAD 6641, by an individual scale of 1.0, and combines it with other RLOADs to create a single load. Furthermore, DLOAD defines load condition DLOAD 612 multiplied by an overall scale of 1.0. In the modified example, there is only one RLOAD to be combined, but there may be multiple RLOADs.

[0143] In data D10A, "MPCADD 620 621 622 23 24 25" groups together the multi-point constraint MPCs defined by identification numbers 621, 622, 23, 24, and 25, i.e., MPCs 621, 622, 23, 24, and 25, and newly defines it as MPCADD620.

[0144] In data D10A, "SPCADD 607 30 35" groups together the single-point constraint SPCs defined by identification numbers 30 and 35, i.e., SPCs 30 and 35, and defines them as SPCADD7. In a modified example, SPC 35 includes an SPC defined in an SPC row (not shown) as a constraint condition that constrains all degrees of freedom other than translation in the X-axis direction at all nodes included in the equivalent mechanical element circuit 710B.

[0145] As described above, the numerical calculation model data DA3 and the numerical calculation model data DA4 describe the calculation method shown in the flowchart of Fig. 6 in the equivalent mechanical element circuit 710B shown in Fig. 25. By using the numerical calculation model data DA3 and the numerical calculation model data DA4, the calculation device 100 can analyze the sound pressure characteristics of the FEM model 724 in which electric circuits in a two-way speaker system are converted into equivalent mechanical element circuits and integrated into one mechanical acoustic system.

[0146] Next, the names of the nodes in the FEM model in which the speaker unit 31B and the tweeter unit 31C are separated are defined with reference to Fig. 31. The displacement constraint 759C is defined as "GRID1654", and the displacement constraint 759B is defined as "GRID2654".

[0147] Next, with reference to Fig. 32, a description will be given of numerical calculation model data DA5 capable of analyzing the sound pressure characteristics of an equivalent mechanical element circuit for calculating the sound pressure contribution of the tweeter unit 31C shown in Fig. 26. In Fig. 32, only changes from the numerical calculation model data DA3 shown in Fig. 29 and the numerical calculation model data DA4 shown in Fig. 30 are described.

[0148] The numerical calculation model data DA5 includes data D7B and data D8B.

[0149] Data D7B is a data structure describing the processing content of step St202 of the placement step of a mechanical element circuit equivalent to an electric circuit in the flowchart shown in Fig. 6. Data D7B defines the coordinates of each of GRID1654, GRID1649, GRID2654, and GRID2649 as the definition of a node. In data D7B, the computing device 100 deletes node 641 corresponding to the drive end point of connector 754.

[0150] The data D8B has a data structure describing the processing contents of step St204 of the vibration displacement speed setting step in the flowchart shown in FIG.

[0151] The data D8B defines an end point for inputting a displacement speed for exciting the equivalent mechanical element circuit 710BC. In the data D8B, "SPC 30 1649 1 0.0" defines that the X degree of freedom of GRID1649 (i.e., ground terminal 49C) is temporarily constrained to a displacement of 0 (zero). In the data D8B, "SPC 30 2649 1 0.0" defines that the X degree of freedom of GRID2649 (i.e., ground terminal 49B) is temporarily constrained to a displacement of 0 (zero). In the data D8B, "SPC 30 1654 1 0.0" defines that the X degree of freedom of GRID1654 (i.e., displacement constraint 759C) is temporarily constrained to a displacement of 0 (zero). In the data D8B, "SPC 30 2654 1 0.0" defines that the X degree of freedom of GRID2654 (i.e., displacement constraint 759B) is temporarily constrained to a displacement of 0 (zero). In the data D8B, a forced displacement constraint is defined by SPCD on the side of GRID1654 (i.e., displacement constraint 759C). In the data D8B, "SPCD 631 1654 1 1.0" defines that either a forced displacement velocity or a forced displacement acceleration is applied to GRID1654 (i.e., displacement constraint 759C) at a value 1.0 times the set value. As described above, the data D8B defines the position where the boundary condition of the displacement velocity is input. In addition, although omitted in FIG. 30 because it is similar to the data D9A in FIG. 29, RLOAD1 (not shown) sets the forced drive point of the dynamic load 6641 to the node 1654 of the connector 54A.

[0152] Next, with reference to Fig. 33, a description will be given of numerical calculation model data DA6 capable of analyzing the sound pressure characteristics of an equivalent mechanical element circuit for calculating the sound pressure contribution of the speaker unit 31B shown in Fig. 27. In Fig. 33, only changes from the numerical calculation model data DA5 shown in Fig. 32 will be described.

[0153] The numerical calculation model data DA6 includes data D8C.

[0154] The data D8C has a data structure describing the processing contents of step St204 of the vibration displacement speed setting step in the flowchart shown in FIG.

[0155] In data D8C, a forced displacement constraint is defined by SPCD on the side of GRID2654 (i.e., displacement constraint 759B). In data D8C, "SPCD631 2654 1 1.0" defines that either a forced displacement velocity or a forced displacement acceleration is applied to GRID2654 (i.e., displacement constraint 759B) at a value 1.0 times the set value. As described above, data D8C defines the position where the boundary condition of the displacement velocity is input. Also, although omitted in FIG. 33 because it is similar to data D9A in FIG. 30, RLOAD1 (not shown) sets the forced drive point of dynamic load 6641 to node 2654 of connector 54B.

[0156] Next, an example of a method of describing the relative acceleration proportional mass 701M for a low-pass filter and the relative acceleration proportional mass 704M for a high-pass filter in the numerical calculation model data will be described with reference to Fig. 34. The numerical calculation model data DA7 includes data D9.

[0157] Data D9 is a data structure describing the processing content of step St202 in the placement step of a mechanical element circuit equivalent to an electric circuit in the flowchart shown in Fig. 6. Data D9 defines the coordinates of GRID701 and GRID702 as the definition of nodes.

[0158] The relative acceleration proportional mass for low-pass filter 701M and the relative acceleration proportional mass for high-pass filter 704M are described in accordance with a prescribed format in the numerical calculation model data, similar to the spring element and the damper element. For example, in the numerical calculation model data conforming to Nastran, they are defined in the relative acceleration mass definition line of CMASS2 shown in FIG. 34. The relative acceleration mass definition line of CMASS2 includes, in the described order, a definition declaration of a mass element, a unique element identification number, a mass of the mass element, a node number of node 1, a component number on the displacement coordinate system that defines the displacement direction of node 1 specified in the CD entry of the GRID data, a node number of node 2, and a component number on the displacement coordinate system that defines the displacement direction of node 2 specified in the CD entry of the GRID data. Here, the CD entry represents the identification number of the coordinate system in which the displacement, the degree of freedom, the constraint condition, and the solution vector are defined at the node. In data D7, the CMASS2 definition line is "CMASS2 71 3.0000-8 701 1 702 1", and between GRID701 and GRID702, there is a "3.0000-8Ns" grid, which corresponds to a relative acceleration mass of a capacitor with a capacitance of 30 μF. 2 / mm(ton)". The mass value of the mass element 71 is input by converting a value equal to the capacitance in the N-kg-m unit system into a predetermined unit system.

[0159] In this modification, the mass proportional to relative acceleration is defined using the CMASS2 element capable of defining the inertial force proportional to the relative acceleration between node 1 and node 2, but the definition of the mass proportional to relative acceleration is not limited to this. In particular, when the processing system for numerical calculation handles only the inertial force proportional to the absolute displacement acceleration, an equivalent mass proportional to relative acceleration expressed by a link mechanism using an equal lever and a mass proportional to absolute displacement acceleration of four times the mass described in Non-Patent Document 1 may be used.

[0160] (Summary of this embodiment) The above description of the present embodiment discloses the following techniques.

[0161] <Technology 1> The calculation method of this embodiment is a calculation method for calculating at least one of the vibration and sound pressure generated in an electromechanical system of a speaker or actuator including an electromechanical energy converter having a stationary electrical impedance Ze when a drive voltage is applied to the electromechanical energy converter, and includes a first step of arranging in a virtual space an equivalent mechanical element circuit that is directly or indirectly connected to a point of application at which a drive force generated in the electromechanical energy converter of a model in a virtual space acts, and that includes at least an electrical impedance equivalent mechanical element having properties mechanically equivalent to the electrical impedance Ze of the electromechanical energy converter, and a second step of setting a displacement velocity equivalent to the drive voltage applied to the electromechanical energy converter as a boundary condition at any of the end points of the equivalent mechanical element circuit or at a node indirectly connected to the end point and serving as an end point.

[0162] As a result, the calculation method according to the present embodiment can replace an electromechanical energy converter including an electric circuit that needs to be coupled with a mechanoacoustic system with an equivalent mechanical element circuit including an electric impedance equivalent mechanical element having properties that are dynamically equivalent to the electric impedance of the electromechanical energy converter, and create an FEM model that can be directly integrated with the mechanoacoustic system. As a result, the calculation method can calculate at least one of the vibration and sound pressure generated in the electromechanical system in a single large-scale calculation by using an FEM model in which the electromechanical energy converter is integrated with the mechanoacoustic system. In other words, the calculation method can reduce the load on the processor that executes the calculation process and shorten the time required for the calculation process.

[0163] <Technology 2> In the calculation method described in Technology 1, the electromechanical energy converter includes a voice coil having an electrical impedance Ze, and in a first step, the electrical impedance Ze of the voice coil is converted into an electrical impedance equivalent mechanical element having mechanically equivalent properties.

[0164] As a result, the calculation method according to the present embodiment can replace the electromechanical energy converter using a voice coil with an equivalent mechanical element circuit including an electric impedance equivalent mechanical element having properties dynamically equivalent to the electric impedance of the voice coil, and create an FEM model that can be directly integrated with the mechanical acoustic system. As a result, the calculation method can calculate at least one of the vibration and sound pressure generated in the electromechanical system with only one large-scale calculation, without performing separate calculations for the electromechanical energy converter using a voice coil and the mechanical acoustic system.

[0165] <Technology 3> In the calculation method described in the first or second technique, the electrical impedance equivalent mechanical element includes at least a mechanical resistance de calculated from Re, which is a direct current resistance component of the electrical impedance Ze, as de=1 / Re.

[0166] As a result, the calculation method according to the present embodiment can create one FEM model by integrating the mechanoacoustic element that receives an excitation force from the electromechanical energy converter and vibrates, and the mechanical element that converts the electromechanical energy converter into a mechanical element, even for a model in which the electric impedance Ze is simplified to only the DC resistance component Re. As a result, the calculation method can accurately calculate at least one of the vibration and sound pressure generated in the electromechanical system with only one large-scale calculation.

[0167] <Technology 4> In the calculation method according to any one of Techniques 1 to 3, the boundary condition set in the second step includes a displacement constraint in which both primary terminals of the equivalent mechanical element circuit are short-circuited to ground.

[0168] In the FEM model created in this way, the output terminal of the voltage amplifier in the electric circuit is set to an internal resistance of 0, and in passive AC operation, the same boundary condition as when it is shorted to ground is correctly reproduced. As a result, the calculation method according to the present embodiment can accurately calculate at least one of the vibration and sound pressure generated in the electromechanical system with only one large-scale calculation.

[0169] <Technology 5> In the calculation method according to any one of Techniques 1 to 4, at least one of vibration and sound pressure generated in an electromechanical system including a plurality of electromechanical energy converters is calculated, in a first step, an equivalent mechanical element circuit is arranged in each of the plurality of electromechanical energy converters, and an end point is further arranged by connecting a plurality of nodes which are indirectly connected to any end point or the end point of each equivalent mechanical element circuit, and in a second step, a boundary condition is set at the end point connecting the plurality of nodes, the boundary condition being a displacement velocity equivalent to a drive voltage.

[0170] As a result, the calculation method according to the present embodiment can calculate the total sound pressure of the reproduced sound of a speaker system including a plurality of speaker units in a single calculation.

[0171] <Technology 6> A calculation method according to Technology 4 is a calculation method for calculating at least one of vibration and sound pressure generated in an electromechanical system including a plurality of electromechanical energy converters, in which in a first step, a plurality of equivalent mechanical element circuits equivalent to each of the plurality of electromechanical energy converters are arranged, and boundary conditions that constrain any one of the end points of each equivalent mechanical element circuit or all nodes that are indirectly connected to the end points and serve as end points are set to a predetermined displacement speed, and in a second step, the boundary conditions are set such that a predetermined non-zero displacement speed is set at any one of the end points of one of the plurality of equivalent mechanical element circuits, and the displacement speeds input to the end points or nodes of the other equivalent mechanical element circuits are set to zero.

[0172] As a result, the calculation method according to the present embodiment can calculate the sound pressure contribution of each speaker unit in a speaker system having multiple speaker units and calculate the total sound pressure of the speaker system by using the principle of superposition. As a result, the calculation method can easily calculate the complex mutual influence of the sound pressure transfer functions of a speaker system in which multiple speaker units are arranged.

[0173] <Technology 7> In the calculation method according to any one of Techniques 1 to 6, the equivalent mechanical element circuit further includes a mass element corresponding to a capacitor that is an electrical component constituting a filter circuit connected to the outside of the electromechanical energy converter.

[0174] As a result, the calculation method according to the present embodiment can easily calculate the sound pressure characteristics of a speaker system that takes into account the influence of an analog filter that is configured as an electric circuit including a capacitor.

[0175] <Technology 8> In the numerical calculation model data according to any one of Techniques 1 to 7, the positional relationship and connection conditions of the mechanical elements of the equivalent mechanical element circuit, the boundary conditions of the displacement velocity, and the elements for which the boundary conditions of the displacement velocity are set are defined.

[0176] As a result, the numerical calculation model data according to this embodiment can specify that the electromechanical energy converter is converted into an equivalent mechanical element circuit, and the mechanical acoustic system and the electrical circuit system are integrated into one FEM model.

[0177] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications, corrections, substitutions, additions, deletions, and equivalents within the scope of the claims, and it is understood that these also belong to the technical scope of the present disclosure. In addition, the components in the above-mentioned embodiments may be arbitrarily combined within the scope of the invention. [Industrial Applicability]

[0178] The technology disclosed herein is useful as a calculation method and numerical calculation model data that reduce the calculation load of the vibration characteristics and sound pressure characteristics of an electromechanical system. [Explanation of symbols]

[0179] 10 Unit Electric Circuit 10A, 10B, 200, 201, 610B, 610BA, 610BB, 710B, 710BB, 710BC Equivalent mechanical element circuit 11,16,17,18,19 Terminals 49,49A,49B,49C,739C,739B Ground terminal 41, 41A, 41B, 741 Termination block 47, 48, 47A, 48A, 47B, 48B, 47C, 48C Driving force application end point 50,51 Midpoint 54,56,57 end points 59, 59A, 59B, 759, 759B, 759C Displacement constraint 60,660,660A,660B,760,760B,760C Forced Displacement Speed 12 Voltage Amplifier 13 Voice coil DC resistance 14 Voice coil inductance 15 Electromechanical Virtual Transformer 20,20A,20B,20C diaphragm 21 Magnetic Circuit 23 Sound pressure observation point 30,630,730 Speaker system 31, 31A, 31B Speaker unit 32,632,732 Case 34,34A,34B,34C Center of gravity 35,35A,35B,35C center point 37,637,737,739 Interior Acoustic Space 39,639 External Acoustic Space 42,42A,42B,45,55,754,754B,754C connector 43,52 Spring 44,53 Damper 46 Lever 111 Electrical Circuits 324,624 FEM models 520,620,720 Structural Model 521,621,721 Spatial Model 522 Sound absorbing surface 523 Mechanism FEM model 31C Tweeter unit 616A, 616B, 619A, 619B, 716A, 716B, 719A, 719B Electrical terminals 701 Low-pass filter capacitor 702 Low-pass filter coil 703 High-pass filter coil 704 High-pass filter capacitor 790 Dividing Network Circuit 701M Relative Acceleration Proportional Mass for Low-Pass Filter 702M Coil equivalent spring for low pass filters 703M Coil equivalent spring for high pass filters 704M Relative Acceleration Proportional Mass for High Pass Filter 741B Lowpass Filter Termination Block 741C High Pass Filter Termination Block

Claims

1. A calculation method for calculating at least one of vibration and sound pressure generated in an electromechanical system of a speaker or actuator, the electromechanical system including an electromechanical energy converter having a static electrical impedance Ze, when a drive voltage is applied to the electromechanical energy converter, the calculation method comprising: A first step of arranging, in a virtual space, an equivalent mechanical element circuit including at least an electrical impedance equivalent mechanical element that is directly or indirectly connected to a point of application on which a driving force generated in the electromechanical energy converter of a model in a virtual space acts and has properties that are dynamically equivalent to the electrical impedance Ze of the electromechanical energy converter; A second step of setting a displacement velocity equivalent to the driving voltage applied to the electromechanical energy converter as a boundary condition at any one of end points of the equivalent mechanical element circuit or at a node indirectly connected to the end point and serving as an end point. Calculation method.

2. the electromechanical energy converter includes a voice coil, the electrical impedance of which is Ze; In the first step, the electric impedance Ze of the voice coil is converted into the electric impedance equivalent mechanical element having a mechanically equivalent property. The calculation method according to claim 1 .

3. The electrical impedance equivalent mechanical element includes at least a mechanical resistance de calculated from Re, which is a direct current resistance component of the electrical impedance Ze, as de = 1 / Re. The calculation method according to claim 1 .

4. The boundary conditions set in the second step include a displacement constraint in which both primary side terminals of the equivalent mechanical element circuit are short-circuited to ground. The calculation method according to claim 1 .

5. A calculation method for calculating at least one of vibration and sound pressure generated in an electromechanical system including a plurality of said electromechanical energy converters, comprising: In the first step, a plurality of equivalent mechanical element circuits equivalent to the plurality of electromechanical energy converters are arranged, Further arranging an end point which is a node indirectly connected to any one of the end points of each of the equivalent mechanical element circuits or the end point, and which serves as an end point, The boundary condition set in the second step is to set a displacement velocity equivalent to the driving voltage as a boundary condition at an end point connecting the plurality of nodes. The calculation method according to claim 1 .

6. A calculation method for calculating at least one of vibration and sound pressure generated in an electromechanical system including a plurality of said electromechanical energy converters, comprising: In the first step, a plurality of equivalent mechanical element circuits equivalent to the plurality of electromechanical energy converters are arranged, A boundary condition is set to constrain a displacement velocity to a predetermined value at any one of the end points of each of the equivalent mechanical element circuits or at all nodes indirectly connected to the end points, The boundary conditions set in the second step include setting a predetermined non-zero displacement speed at any end point of one of the plurality of equivalent mechanical element circuits, and setting displacement speeds input to end points or nodes of the other equivalent mechanical element circuits to zero. The calculation method according to claim 1 .

7. The equivalent mechanical element circuit further includes a mass element corresponding to a capacitor which is an electrical component constituting a filter circuit connected to the outside of the electromechanical energy converter. The calculation method according to claim 1 .

8. Defining a positional relationship and a connection condition of components of the equivalent mechanical element circuit, a boundary condition of the displacement velocity, and an element for which the boundary condition of the displacement velocity is set; Numerical calculation model data describing at least the calculation method according to any one of claims 1 to 7.

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