Sound system

Abstract

Provided is a sound system in which the stroke width of a speaker is increased by suppressing the winding width. In accordance with the displacement of the vibration system, the driving polarity of a voice coil VC2 disposed separately below the voice coils VC1 and VC1 is switched. The driving polarity of the VC1 is set as a first polarity when a part of the VC1 is located in a magnetic gap GAP1, and is set as a second polarity opposite to the first polarity when the part of the VC1 is located in a magnetic gap GAP2, and the driving polarity of the VC2 is set as a second polarity when a part of the VC2 is located in the GAP2, and is set as the first polarity when the part of the VC2 is located in the GAP1. The VC1 and the VC2 are separately arranged below the GAP1, the GAP2 is separately arranged below the GAP1, the magnetic flux directions of the GAP1 and the GAP2 are opposite, the winding width of the VC1 and the VC2 is smaller than the interval between the GAP1 and the GAP2, the upper end of the VC2 enters the GAP1 before the VC1 is separated from the GAP1 at the upper part of the lower end of the VC1, and the lower end of the VC2 enters the GAP2 from the GAP2 at the lower part of the VC2.

Description

Technical Field

[0001] This invention relates to a technique for extending the travel width of a loudspeaker that can be effectively controlled. Background Technology

[0002] As a technology related to the present invention, there is a known technology in which the total winding width of the upper magnetic gap and the lower magnetic gap, which are two magnetic gaps with opposite directions of magnetic flux, the upper voice coil with a winding width L and the lower voice coil with a winding width L opposite to the upper voice coil, is set such that the total winding width of the lower part of the upper voice coil in the upper magnetic gap and the upper part of the lower voice coil in the lower magnetic gap is L, thereby obtaining a certain driving force regardless of the displacement of the speaker's vibration system (for example, Patent Document 1).

[0003] In addition, as a technology related to the present invention, there are known techniques for detecting the displacement of a loudspeaker's vibration system using accelerometers, velocity sensors, displacement sensors, etc. (for example, Patent Document 2).

[0004] [Existing Technical Documents]

[0005] [Patent Literature]

[0006] Patent Document 1: Japanese Patent Application Publication No. 9-163495

[0007] Patent Document 2: Japanese Patent Application Publication No. 2007-81815 Summary of the Invention

[0008] Even small-diameter loudspeakers can reproduce bass just like large-diameter loudspeakers by ensuring a large travel width.

[0009] Furthermore, increasing the travel width requires increasing the voice coil winding width (coil length) to prevent the voice coil from shifting out of control and becoming uncontrollable. However, if the winding width is greater than the gap width, the driving force acting on the voice coil is less than that of a voice coil with a winding width equal to the gap width. On the other hand, increasing the input gain of the voice coil can increase the driving force acting on it, but this increases power consumption. Additionally, increasing the winding width increases the weight of the vibrating system including the voice coil, which is detrimental to output sound pressure levels.

[0010] Therefore, the objective of this invention is to increase the travel width of the driven loudspeaker while suppressing the winding width of the voice coil.

[0011] To achieve the aforementioned objective, the present invention provides an audio system equipped with a loudspeaker, comprising: a displacement detection unit for detecting the axial displacement of the loudspeaker in a vibration system; and a drive unit for driving the loudspeaker using an audio signal. Here, the loudspeaker has a first magnetic gap, a second magnetic gap overlapping the first magnetic gap when viewed axially, and a plurality of voice coils fixed axially spaced apart from each other in the vibration system such that they are located inside the first and second magnetic gaps when viewed axially. Furthermore, the first magnetic gap propagates magnetic flux in one radial direction of the loudspeaker, and the second magnetic gap propagates magnetic flux in another radial direction. The axial distance between the first and second magnetic gaps is larger than the winding width of each voice coil. The vibration system is configured to vibrate between a position where at least a portion of the voice coils are inside the first magnetic gap and a position where they are inside the second magnetic gap. Furthermore, the driving unit uses the audio signal as a driving signal to drive each voice coil, and at least uses a driving signal of the first polarity to drive the voice coil whose displacement detected by the displacement detection unit indicates that it is located inside the first magnetic gap, and uses a driving signal of the second polarity to drive the voice coil whose displacement detected by the displacement detection unit indicates that it is located inside the second magnetic gap, wherein the second polarity is the opposite polarity to the first polarity.

[0012] Furthermore, to achieve the aforementioned goal, the present invention provides an audio system equipped with a loudspeaker, comprising: a displacement detection unit for detecting the axial displacement of the loudspeaker in a vibration system; and a drive unit for driving the loudspeaker using an audio signal. The loudspeaker has a first magnetic gap, a second magnetic gap overlapping the first magnetic gap when viewed axially, and a first voice coil and a second voice coil fixed to the vibration system such that they are located inside the first and second magnetic gaps when viewed axially. Moreover, with one axial direction of the loudspeaker positioned upwards and the other downwards, the first magnetic gap is positioned above the second magnetic gap at an axial interval, and the first voice coil is positioned above the second voice coil at an axial interval. Additionally, the first magnetic gap propagates magnetic flux in one radial direction of the loudspeaker, and the second magnetic gap propagates magnetic flux in the other radial direction; the axial interval between the first and second magnetic gaps is larger than the winding width of the first and second voice coils. Furthermore, the vibration system is configured to vibrate between a position where at least a portion of the first and second voice coils are located inside the first magnetic gap and a position where they are located inside the second magnetic gap. Furthermore, when the displacement detected by the displacement detection unit indicates that at least a predetermined proportion of the first voice coil is located inside the first magnetic gap, the driving unit drives the first voice coil using a driving signal of the first polarity. When the displacement detected by the displacement detection unit indicates that at least a predetermined proportion of the first voice coil is located inside the second magnetic gap, the driving unit drives the first voice coil using a driving signal of the second polarity, wherein the second polarity is the opposite of the first polarity. When the displacement detected by the displacement detection unit indicates that at least a predetermined proportion of the second voice coil is located inside the first magnetic gap, the driving unit drives the second voice coil using a driving signal of the first polarity. When the displacement detected by the displacement detection unit indicates that at least a predetermined proportion of the second voice coil is located inside the second magnetic gap, the driving unit drives the second voice coil using a driving signal of the second polarity.

[0013] Preferably, the audio system is configured such that, within a first range of displacement of the vibration system, both the portion of the first voice coil exceeding a predetermined proportion and the portion of the second voice coil exceeding a predetermined proportion are located inside the first magnetic gap; and within a second range of displacement of the vibration system, both the portion of the first voice coil exceeding a predetermined proportion and the portion of the second voice coil exceeding a predetermined proportion are located inside the second magnetic gap. In the drive unit, when the displacement detected by the displacement detection unit indicates that both the portion of the first voice coil exceeding a predetermined proportion and the portion of the second voice coil exceeding a predetermined proportion are located inside the first magnetic gap, the first voice coil and the second voice coil are driven using a drive signal of the first polarity; and when the displacement detected by the displacement detection unit indicates that both the portion of the first voice coil exceeding a predetermined proportion and the portion of the second voice coil exceeding a predetermined proportion are located inside the second magnetic gap, the first voice coil and the second voice coil are driven using a drive signal of the second polarity.

[0014] Alternatively, in this case, the driving unit may stop driving the first voice coil when the displacement detected by the displacement detection unit indicates that the portion of the first voice coil exceeding the predetermined proportion is neither inside the first magnetic gap nor inside the second magnetic gap, and the driving unit may stop driving the second voice coil when the displacement detected by the displacement detection unit indicates that the portion of the second voice coil exceeding the predetermined proportion is neither inside the first magnetic gap nor inside the second magnetic gap.

[0015] Here, the portion exceeding a predetermined proportion of the first voice coil may be the portion exceeding n% (where n > 0) of the first voice coil, and the portion exceeding a predetermined proportion of the second voice coil may be the portion exceeding n% of the second voice coil.

[0016] Furthermore, the above-described audio system can be configured such that when the upper half of the first voice coil is located within the lower part of the first magnetic gap, the lower half of the second voice coil is located within the upper part of the second magnetic gap.

[0017] More specifically, for example, the winding width of the first voice coil and the second voice coil can be set to L, and the axial spacing between the first voice coil and the second voice coil can be set to 0.5L.

[0018] In addition, in this case, it is preferable that the axial length of the first magnetic gap and the second magnetic gap is 1.5L.

[0019] According to the above-described audio system, at least a portion of the multiple voice coils provided with different axial ranges can selectively act on both a first magnetic gap and a second magnetic gap with different axial ranges and opposite magnetic flux orientations to drive the loudspeaker. Therefore, the winding width of the voice coils can be suppressed, and the driving force can be maintained over a wide displacement range of the vibration system. As a result, the travel width of the loudspeaker that can be effectively controlled can be expanded.

[0020] [Invention Effects]

[0021] As described above, according to the present invention, it is possible to increase the travel width of the driven loudspeaker while suppressing the winding width of the voice coil. Attached Figure Description

[0022] Figure 1 This is a diagram showing the structure of an audio system according to an embodiment of the present invention.

[0023] Figure 2 This is a diagram showing the structure of a loudspeaker according to an embodiment of the present invention.

[0024] Figure 3 This is a diagram showing the configuration relationship between the magnetic gap and the voice coil in an embodiment of the present invention.

[0025] Figure 4 This is a diagram illustrating the drive control of the voice coil according to an embodiment of the present invention.

[0026] Figure 5 This is a diagram illustrating another example of voice coil drive control according to an embodiment of the present invention.

[0027] Figure 6 This is a diagram illustrating an example of the zero-one structure of a loudspeaker according to an embodiment of the present invention.

[0028] Figure 7 This is a diagram illustrating another structural example of an audio system according to an embodiment of the present invention. Detailed Implementation

[0029] The embodiments of the present invention will be described below.

[0030] Figure 1 This describes the structure of the audio system in this embodiment.

[0031] As shown in the figure, the audio system includes a sound source device 1 for outputting audio signals, a loudspeaker 2, a displacement sensor 3 for the loudspeaker 2, a signal processing device 4, a first amplifier 5, and a second amplifier 6.

[0032] The signal processing device 4 can be configured using a DSP (Digital Signal Processor), and includes a first gain adjustment unit 41, a second gain adjustment unit 42, a first drive polarity control unit 43, a second drive polarity control unit 44, a displacement detection unit 45, and a control unit 46.

[0033] then, Figure 2 The 'a' indicates the structure of speaker 2.

[0034] As shown in the figure, the loudspeaker 2 has a base 201, a magnetic yoke 202, a voice coil skeleton 203, a dust cover 204, a first voice coil VC1 (205), a second voice coil VC2 (206), a first plate 207, a second plate 208, a magnet 209, a frame 210, a spider 211, a diaphragm 212, and a displacement detection magnet 213.

[0035] Here, if the upward direction in the axis of the speaker 2 is defined as the upward direction of the speaker 2, and the downward direction is defined as the downward direction of the speaker 2, then the yoke 202 has a cylindrical shape and is supported at the center of the base 201. The voice coil frame 203 has a hollow cylindrical shape, and the yoke 202 is inserted from below in a manner that allows the voice coil frame 203 to move up and down relative to the yoke 202. A first voice coil VC1 (205) is wound around the outer periphery of the voice coil frame 203, and a second voice coil VC2 (206) is wound around the first voice coil VC1 (205) at a position away from the first voice coil VC1 (205).

[0036] In addition, on the outside of the voice coil frame 203, the annular second plate 208, the annular magnet 209, and the annular first plate 207, which are supported on the outer periphery of the base 201, are arranged in a manner that is stacked sequentially from below.

[0037] Here, the yoke 202 and the second plate 208 are electrically and magnetically separated through the base 201, and a magnetic circuit of magnetic loop is formed through the yoke 202, the second plate 208, the magnet 209, and the first plate 207, which is magnet 209-second plate 208-yoke 202-first plate 207-magnet 209.

[0038] The frame 210 is fixed to the base 201 via the magnetic yoke 202, the first plate 207, the magnet 209 and the second plate 208. The outer peripheral end of the vibrating plate 212 is fixed to the frame 210 and the inner peripheral end is fixed to the voice coil skeleton 203.

[0039] Next, the displacement detection magnet 213 is fixed to the outer periphery of the voice coil frame 203 by moving up and down together with the voice coil frame 203, generating a magnetic flux in a direction orthogonal to the magnetic flux generated by the magnetic circuit.

[0040] Furthermore, the aforementioned displacement sensor 3 is fixed to the non-vibration system of the speaker 2, such as the first plate 207, at a position close to the displacement detection magnet 213. The displacement sensor 3 is a magnetic angle sensor, such as... Figure 2 As shown in b, the arctangent Qs / Qc of the angle between the composite vector Q of the magnetic flux vector Qc acting from the magnetic circuit and the magnetic flux vector Qs acting from the displacement detection magnet 211 is used as the magnetic angle for detection and output. The magnetic flux vector generated by the displacement detection magnet 213 acting on the displacement sensor 3 changes due to the displacement of the voice coil frame 203 in the vertical direction. Therefore, this magnetic angle becomes a value corresponding to the vertical displacement of the voice coil frame 203, i.e., the vertical displacement position of the vibration system of the loudspeaker 2.

[0041] Figure 3 Figure a shows the positional relationship of the yoke 202, the first voice coil VC1 (205), the second voice coil VC2 (206), the first plate 207, the second plate 208, and the magnet 209.

[0042] like Figure 3 As shown in Figure b, a first magnetic gap GAP1 for magnetic flux passage is formed between the first plate 207 and the magnetic yoke 202, and a second magnetic gap GAP2 for magnetic flux passage is formed between the second plate 208 and the magnetic yoke 202. Additionally, as... Figure 3 As shown in Figure c, the direction of the magnetic flux through the first magnetic gap GAP1 and the direction of the magnetic flux through the second magnetic gap GAP2 are radial to the speaker 2 and opposite to each other.

[0043] Furthermore, the winding widths (coil length / vertical height) of the first voice coil VC1 (205) and the second voice coil VC2 (206) are equal. Additionally, the winding widths of the first voice coil VC1 (205) and the second voice coil VC2 (206) are set to L, and the interval between the first magnetic gap GAP1 and the second magnetic gap GAP2 is greater than L, ensuring that the first voice coil VC1 (205) and the second voice coil VC2 (206) do not simultaneously enter both the first magnetic gap GAP1 and the second magnetic gap GAP2. Furthermore, the dimensions and configuration of each part are determined such that before the voice coil skeleton 203 moves upward and the lower end of the first voice coil VC1 (205) separates from the first magnetic gap GAP1 above, the upper end of the second voice coil VC2 (206) enters the first magnetic gap GAP1, and before the voice coil skeleton 203 moves downward and the lower end of the second voice coil VC2 (206) separates from the second magnetic gap GAP2 below, the lower end of the first voice coil VC1 (205) enters the second magnetic gap GAP2.

[0044] In this embodiment, we will take the case where the width of the first magnetic gap GAP in the vertical direction is 1.5L, the width of the second magnetic gap GAP2 in the vertical direction is 1.5L, the width of the gap between the first magnetic gap GAP1 and the second magnetic gap GAP2 in the vertical direction is 1.5L, and the gap between the first voice coil VC1 (205) and the second voice coil VC2 (206) in the vertical direction is 0.5L as an example.

[0045] In addition, in this embodiment, the first voice coil VC1 (205) and the second voice coil VC2 (206) are configured such that, in a neutral state where no signal is applied to the first voice coil VC1 (205) and the second voice coil VC2 (206), the upper half of the first voice coil VC1 (205) is located at the lower part of the first magnetic gap GAP1, and the lower half of the second voice coil VC2 (206) is located at the upper part of the second magnetic gap GAP2.

[0046] Next, in the following... Figure 3 The direction of the current is set to positive when the front of the paper faces the back (backwards), and will flow from... Figure 3 The direction of the current with the back side of the paper facing the front (forward) is set to reverse. The direction of the magnetic flux through the first magnetic gap GAP1 and the direction of the magnetic flux through the second magnetic gap GAP2 are as follows: Figure 3 In the case shown in c, when at least a portion of the first voice coil VC1 (205) is located in the first magnetic gap GAP1, if as Figure 3 As shown in d1, a positive current flows through the first voice coil VC1 (205), thus applying an upward force to the voice coil frame 203. Similarly, as Figure 3 As shown in d2, when at least a portion of the second voice coil VC2 (206) is located in the first magnetic gap GAP1, if a positive current flows through the second voice coil VC2 (206), an upward force is applied to the voice coil frame 203. On the other hand, as Figure 3 As shown in d3, when at least a portion of the first voice coil VC1 (205) is located within the second magnetic gap GAP2, if a reverse current flows through the first voice coil VC1 (205), an upward force is applied to the voice coil frame 203. Similarly, when at least a portion of the second voice coil VC2 (206) is located within the second magnetic gap GAP2, if... Figure 3 If a current flows in the opposite direction as shown in d4 through the second voice coil VC2 (206), an upward force is applied to the voice coil frame 203. Conversely, if the direction of the current is reversed, forces in opposite directions are applied to the voice coil frame 203.

[0047] Therefore, as long as at least a portion of at least one of the first voice coil VC1 (205) and the second voice coil VC2 (206) is located within at least one of the first magnetic gap GAP1 and the second magnetic gap GAP2, an audio signal can be applied to the first voice coil VC1 (205) and the second voice coil VC2 (206) with appropriate polarity and gain. Thus, through the electromagnetic interaction of the magnetic flux generated in the first magnetic gap GAP1 and the second magnetic gap GAP2 and the current flowing through the first voice coil VC1 (205) and the second voice coil VC2 (206), a vibration corresponding to the amplitude of the audio signal can be applied to the vibrating plate 212 via the voice coil frame 203, thereby generating a sound corresponding to the audio signal.

[0048] Additionally, return to Figure 1 The displacement detection unit 45 of the signal processing device 4 calculates the vertical displacement position ΔZ of the vibration system of the loudspeaker 2 based on the magnetic angle detected by the displacement sensor 3 and outputs it to the control unit 46.

[0049] In addition, the first gain adjustment unit 41 adjusts the gain of the audio signal input from the sound source device 1 with the gain set by the control unit 46 and outputs it to the first drive polarity control unit 43, and the second gain adjustment unit 42 adjusts the gain of the audio signal input from the sound source device 1 with the gain set by the control unit 46 and outputs it to the second drive polarity control unit 44.

[0050] The first drive polarity control unit 43 outputs the audio signal input from the first gain adjustment unit 41 to the first amplifier 5, and performs processing to switch the presence or absence of the audio signal output to the first amplifier 5 according to the control unit 46, and to switch the positive or negative polarity of the audio signal output to the first amplifier 5 according to the control unit 46. Similarly, the second drive polarity control unit 44 outputs the audio signal input from the second gain adjustment unit 42 to the second amplifier 6, and performs processing to switch the presence or absence of the audio signal output to the second amplifier 6 according to the control unit 46, and to switch the positive or negative polarity of the audio signal output to the second amplifier 6 according to the control unit 46.

[0051] The first amplifier 5 amplifies the audio signal input from the first drive polarity control unit 43 with a fixed and predetermined gain and outputs it to the first voice coil VC1 (205) of the speaker 2. The second amplifier 6 amplifies the audio signal input from the second drive polarity control unit 44 with the same gain as the first amplifier 5 and outputs it to the second voice coil VC2 (206) of the speaker 2.

[0052] The control of the first drive polarity control unit 43 and the second drive polarity control unit 44 by the control unit 46 will be described below.

[0053] The control unit 46 controls the switching of the output of the first drive polarity control unit 43 and the second drive polarity control unit 44, as well as the switching of the positive and negative polarities of the output audio signal, based on the vertical displacement position ΔZ of the vibration system of the speaker 2 calculated by the displacement detection unit 45.

[0054] Figure 4 Figure 'a' illustrates the positional relationship between the displacement position ΔZ and the positions of the first voice coil VC1 (205), the second voice coil VC2 (206), the first magnetic gap GAP1, and the second magnetic gap GAP2. Additionally, Figure 4 Figure b1 shows the relationship between the displacement position ΔZ, the presence or absence of the output from the first drive polarity control unit 43 to the first amplifier 5, and the positive or negative polarity of the audio signal output to the first amplifier 5. However, the positive or negative polarity of the audio signal output to the first amplifier 5 is indicated by the direction of the current flowing through the first voice coil VC1 (205) when the value of the audio signal input to the first drive polarity control unit 43 is positive. Furthermore, Figure 4 b2 shows the relationship between the displacement position ΔZ, the presence or absence of the output from the second drive polarity control unit 44 to the second amplifier 6, and the positive or negative polarity of the audio signal output to the second amplifier 6. However, the positive or negative polarity of the audio signal output to the second amplifier 6 is indicated by the direction of the current flowing through the second voice coil VC2 (206) when the value of the audio signal input to the second drive polarity control unit 44 is positive.

[0055] The direction of the current flowing through the first voice coil VC1 (205) and the second voice coil VC2 (206) is from Figure 3 The forward / reverse representations are shown in d1 to d4.

[0056] As shown in the figure, when the first voice coil VC1 (205) is not in the first magnetic gap GAP1 or the second magnetic gap GAP2, the control unit 46 controls the output of the first drive polarity control unit 43 to the first amplifier 5 to stop the output to the first amplifier 5.

[0057] Furthermore, the control unit 46 controls the positive and negative polarities of the audio signal output by the first drive polarity control unit 43 to the first amplifier 5 in the following manner: when at least a portion of the first voice coil VC1 (205) is within the first magnetic gap GAP1, the current flows through the first voice coil VC1 (205) in the positive direction when the value of the audio signal input to the first drive polarity control unit 43 is positive, and when at least a portion of the first voice coil VC1 (205) is within the second magnetic gap GAP2, the current flows through the first voice coil VC1 (205) in the reverse direction when the value of the audio signal input to the first drive polarity control unit 43 is positive.

[0058] In addition, the control unit 46 controls the output of the second drive polarity control unit 44 to the second amplifier 6 in the following manner: when the second voice coil VC2 (206) is not inside the second magnetic gap GAP2 or the first magnetic gap GAP1, the output to the second amplifier 6 is stopped.

[0059] Furthermore, the control unit 46 controls the positive and negative polarities of the audio signal input to the second amplifier 6 by the second drive polarity control unit 44 in the following manner: when at least a portion of the second voice coil VC2 (206) is within the second magnetic gap GAP2, the current flows through the second voice coil VC2 (206) in the reverse direction when the value of the audio signal input to the second drive polarity control unit 44 is positive; and when at least a portion of the second voice coil VC2 (206) is within the first magnetic gap GAP1, the current flows through the second voice coil VC2 (206) in the positive direction when the value of the audio signal input to the second drive polarity control unit 44 is positive.

[0060] As a result, when the displacement position ΔZ is within the range BZ, at least a portion of at least one of the first voice coil VC1 (205) and the second voice coil VC2 (206) is located within at least one of the first magnetic gap GAP1 and the second magnetic gap GAP2, thus enabling the driving force of at least one of the first voice coil VC1 (205) and the second voice coil VC2 (206) to be exerted, and within the range of BZ, through Figure 4 The control unit 46 shown in b1 and b2 can apply force to the voice coil frame 203 in appropriate positive and negative directions relative to the audio signal output by the sound source device 1, causing the vibration system of the loudspeaker 2 to vibrate, wherein the range BZ is Figure 4 The range between the position where the upper end of the first voice coil VC1 (205) in a becomes the lower end of the second magnetic gap GAP2 and the position where the lower end of the second voice coil VC2 (206) becomes the upper end of the first magnetic gap GAP1.

[0061] Here, if only the first magnetic gap GAP1 is set as the magnetic gap and a single voice coil is used to exert driving force within the BZ range, then more than Figure 4 The voice coil VCL is a winding width equal to the sum of the winding widths of the first voice coil VC1 (205) and the second voice coil VC2 (206) shown in c, which is 2L and has a winding width equal to the length from the upper end of the first voice coil VC1 (205) to the lower end of the second voice coil VC2 (206).

[0062] Therefore, according to this embodiment, the travel width of the loudspeaker 2, which can be effectively controlled, can be increased without using a voice coil with a large winding width. Furthermore, since the magnetic circuit is symmetrically constructed, asymmetrical deformation is less likely to occur.

[0063] Return to Figure 1The control unit 46 controls the gain of the first gain adjustment unit 41 and the gain of the second gain adjustment unit 42 in the above structure according to the preset correspondence between the displacement position ΔZ and the combination of the gain of the first gain adjustment unit 41 and the gain of the second gain adjustment unit 42, so as to obtain the response of the first voice coil VC1 (205) and the second voice coil VC2 (206) as the target of the audio signal to be output by the sound source device 1 to the driving force of the vibration system.

[0064] Furthermore, the correspondence between the displacement position ΔZ and the combination of the gain of the first gain adjustment unit 41 and the gain of the second gain adjustment unit 42 is determined such that the upper and lower limits of the displacement position ΔZ for the assumed audio signal to be output by the sound source device 1 converge within the range BZ.

[0065] The embodiments of the present invention have been described above.

[0066] In the above embodiments, when at least a portion of the first voice coil VC1 (205) is located within the first magnetic gap GAP1 or the second magnetic gap GAP2, the first voice coil VC1 (205) is driven; when at least a portion of the second voice coil VC2 (206) is located within the first magnetic gap GAP1 or the second magnetic gap GAP2, the second voice coil VC2 (206) is driven. Alternatively, when a portion of the first voice coil VC1 (205) with a specified length of winding width (e.g., 10% of the winding width of the first voice coil VC1 (205)) is not located within the first magnetic gap GAP1 or the second magnetic gap GAP2, the output to the first voice coil VC1 (205) is stopped; and when a portion of the second voice coil VC2 (206) with a specified length of winding width (e.g., 10% of the winding width of the second voice coil VC2 (206)) is not located within the first magnetic gap GAP1 or the second magnetic gap GAP2, the output to the second voice coil VC2 (206) is stopped.

[0067] In addition, in the above embodiments, the control unit 46 may limit the range of the displacement position ΔZ of the vibration system to a range that is greater than or equal to the sum of the ranges of the first voice coil VC1 (205) and the second voice coil VC2 (206) located in either the first magnetic gap GAP1 or the second magnetic gap GAP2, which is a predetermined width (vertical length).

[0068] That is, for example, it can also be like Figure 5As shown in a, over-amplitude protection control is performed to ensure that the displacement position ΔZ does not deviate from the range CZ between the lower end of the first voice coil VC1 (205) located at the lower end of the second magnetic gap GAP2 and the upper end of the second voice coil VC2 (206) located at the upper end of the first magnetic gap GAP1, and the total range of the first voice coil VC1 (205) and the second voice coil VC2 (206) located within either the first magnetic gap GAP1 or the second magnetic gap GAP2 is greater than L.

[0069] In this case, the correspondence between the displacement position ΔZ and the combination of the gain of the first gain adjustment unit 41 and the gain of the second gain adjustment unit 42 is determined such that the upper and lower limits of the response of the displacement position ΔZ relative to the audio signal output by the assumed sound source device 1 converge within the range CZ.

[0070] In addition, such as Figure 5 As shown in Figure a, the range of displacement position ΔZ is limited to the range CZ. Thus, within the range CZ, the total range of the first voice coil VC1 (205) and the second voice coil VC2 (206) located within either the first magnetic gap GAP1 or the second magnetic gap GAP2 is always L. Therefore, the magnitude of the magnetic flux passing through the first voice coil VC1 (205) and the second voice coil VC2 (206) expands linearly, and the same driving force can be achieved over a wide range.

[0071] Furthermore, in this case, over-amplitude protection control can be achieved by, for example, performing [action] in the control unit 46. Figure 5 This is achieved through control as shown in b1 and b2.

[0072] That is, the control unit 46, located between the lower end of the first voice coil VC1 (205) and the upper end of the first magnetic gap GAP1, controls the polarity of the audio signal output by the first drive polarity control unit 43 to the first amplifier 5 such that when the value of the audio signal input to the first drive polarity control unit 43 is positive, the current flows through the first voice coil VC1 (205) in the positive direction; the lower end of the first voice coil VC1 (205) is located at the lower end of the second magnetic gap GAP1. The position of the upper end of P2 is between the position of the lower end of the first voice coil VC1 (205) and the position of the lower end of the second magnetic gap GAP2, so as to control the positive and negative polarities of the audio signal output by the first drive polarity control unit 43 to the first amplifier 5 in such a way that when the value of the audio signal input to the first drive polarity control unit 43 is positive, the current flows through the first voice coil VC1 (205) in the opposite direction; within other positions within the range CZ, the output of the first drive polarity control unit 43 to the first amplifier 5 is controlled in such a way as to stop the output to the first amplifier 5.

[0073] Furthermore, the control unit 46, located between the upper end of the second voice coil VC2 (206) and the lower end of the second magnetic gap GAP2, controls the polarity of the audio signal input to the second amplifier 6 by the second drive polarity control unit 44 such that when the value of the audio signal input to the second drive polarity control unit 44 is positive, the current flows through the first voice coil VC1 (205) in the opposite direction. The lower end of GAP1 is positioned between the upper end of the second voice coil VC2 (206) and the upper end of the first magnetic gap GAP1, so as to control the positive and negative polarities of the audio signal output by the second drive polarity control unit 44 to the second amplifier 6 when the value of the audio signal input to the first drive polarity control unit 43 is positive, and the output of the second drive polarity control unit 44 to the second amplifier 6 is controlled to stop the output to the second amplifier 6 in other positions within the range CZ.

[0074] Furthermore, the over-amplitude suppression operation is performed when the displacement position ΔZ is in a range larger than or smaller than the range CZ. If the displacement position ΔZ is in a range larger than the range CZ, the second drive polarity control unit 44 generates a braking signal that provides a driving force to the second voice coil VC2 (206) in the opposite direction to the displacement direction indicated by the displacement position ΔZ, and the second amplifier 6 outputs it instead of an audio signal. If the displacement position ΔZ is in a range smaller than the range CZ, the first drive polarity control unit 43 generates a braking signal that provides a driving force to the first voice coil VC1 (205) in the opposite direction to the displacement direction indicated by the displacement position ΔZ, and the first amplifier 5 outputs it instead of an audio signal.

[0075] In addition, the above embodiments show the case where two voice coils, the first voice coil VC1 (205) and the second voice coil VC2 (206), are used as voice coils, but more voice coils can also be set.

[0076] For example, it can also be like Figure 6 The four voice coils VC1-VC4 are configured on the voice coil frame 203, just like in a1.

[0077] according to Figure 6 The configuration shown in a1, in Figure 6 a2 and Figure 6 Within the travel range between a3, the total winding width of all voice coils located in either the first magnetic gap GAP1 or the second magnetic gap GAP2 can be set to L or more, thereby causing the vibration system of the loudspeaker 2 to vibrate.

[0078] Or, for example, it can also be like Figure 6 The five voice coils VC1 to VC5 are arranged on the voice coil frame 203, as in b1.

[0079] according to Figure 6 The structure shown in b1, in Figure 6 b2 and Figure 6 Within the travel range between b3, the total winding width of all voice coils located in either the first magnetic gap GAP1 or the second magnetic gap GAP2 is L or more, thereby causing the vibration system of the loudspeaker 2 to vibrate.

[0080] in addition, Figure 6 a1, Figure 6 Figure b1 illustrates a case where the vertical width of the first magnetic gap GAP is 1.5L, the vertical width of the second magnetic gap GAP2 is 1.5L, the vertical width of the gap between the first magnetic gap GAP1 and the second magnetic gap GAP2 is 1.5L, and the vertical spacing between adjacent voice coils VC is 0.5L. With this structure, identical voice coils VCi (i = 1, 2, ..., n) will not simultaneously enter both the first magnetic gap GAP1 and the second magnetic gap GAP2. Furthermore, the voice coil frame 203 moves upwards, and before the lower end of the k-th voice coil VCk (k = 1, 2, ..., n-1) detaches from the first magnetic gap GAP1 from above, the upper end of the (k+1)-th voice coil VCk+1 enters the first magnetic gap GAP1. The voice coil frame 203 moves downwards, and before the lower end of the j-th voice coil VCj (j = 2, 3, ..., n) detaches from the second magnetic gap GAP2 from below, the lower end of the (j-1)-th voice coil VCj-1 enters the second magnetic gap GAP2.

[0081] In addition, in such Figure 6 a1, Figure 6 In the case of setting more voice coils n, as in b1, such as Figure 7As shown, a group of i-th gain control unit GCI, i-th drive polarity control unit DPCi, and i-th amplifier AMPi corresponding to each voice coil VCI (i = 1, 2, ... n) is configured. When the entire voice coil VCI is neither within the first magnetic gap GAP1 nor the second magnetic gap GAP2, the output of the audio signal from the i-th drive polarity control unit to the i-th amplifier is controlled to stop the output via the i-th amplifier AMPi to the voice coil VCI. In addition, the i-th drive polarity control unit controls the positive and negative polarities of the audio signal output to the i-th amplifier AMPi in the following manner: when at least a portion of the voice coil VCI is located within the first magnetic gap GAP1, the current flows through the first voice coil VC1 (205) in the positive direction when the value of the audio signal input to the first drive polarity control unit 43 is positive; when at least a portion of the first voice coil VCI is located within the second magnetic gap GAP2, the current flows through the i-th voice coil VCI in the reverse direction when the value of the audio signal input to the i-th drive polarity control unit is positive.

[0082] [Explanation of reference numerals in the attached figures]

[0083] 1…Sound source device, 2…loudspeaker, 3…displacement sensor, 4…signal processing device, 5…first amplifier, 6…second amplifier, 41…first gain adjustment unit, 42…second gain adjustment unit, 43…first drive polarity control unit, 44…second drive polarity control unit, 45…displacement detection unit, 46…control unit, 201…base, 202…magnetic yoke, 203…voice coil frame, 204…dust cover, 205…first voice coil VC1, 206…second voice coil VC2, 207…first plate, 208…second plate, 209…magnet, 210…frame, 211…spider, 212…vibrating plate, 213…magnet for displacement detection.

Claims

1. A sound system comprising a loudspeaker, characterized in that, have: A displacement detection unit detects the axial displacement of the loudspeaker in the vibration system of the loudspeaker; and The driver unit uses audio signals to drive the speaker. The loudspeaker has a first magnetic gap, a second magnetic gap that overlaps with the first magnetic gap when viewed axially, and a plurality of voice coils fixed to the vibrating system at axial intervals, located inside the first and second magnetic gaps when viewed axially. The first magnetic gap propagates magnetic flux in one direction of the radial direction of the loudspeaker, and the second magnetic gap propagates magnetic flux in the other direction of the radial direction. The axial spacing between the first magnetic gap and the second magnetic gap is larger than the winding width of each voice coil. The vibration system is configured to vibrate between a position where at least a portion of the voice coils are inside the first magnetic gap and a position where they are inside the second magnetic gap. The driving unit uses the audio signal as a driving signal to drive each voice coil, and at least uses a driving signal of the first polarity to drive the voice coil whose displacement detected by the displacement detection unit indicates that it is located inside the first magnetic gap, and uses a driving signal of the second polarity to drive the voice coil whose displacement detected by the displacement detection unit indicates that it is located inside the second magnetic gap, wherein the second polarity is the opposite polarity to the first polarity.

2. A sound system comprising a loudspeaker, characterized in that, have: A displacement detection unit detects the axial displacement of the loudspeaker in the vibration system of the loudspeaker; and The driver unit uses audio signals to drive the speaker. The loudspeaker has a first magnetic gap, a second magnetic gap that overlaps with the first magnetic gap when viewed in the axial direction, and a first voice coil and a second voice coil fixed to the vibrating system in such a way that they are located inside the first magnetic gap and the second magnetic gap when viewed in the axial direction. With one side of the speaker's axis positioned upwards and the other downwards, a first magnetic gap is positioned above the second magnetic gap, separated by the axial interval. The first voice coil is positioned above the second voice coil at an axial interval. The first magnetic gap propagates magnetic flux in one direction of the radial direction of the loudspeaker, and the second magnetic gap propagates magnetic flux in the other direction of the radial direction. The axial spacing between the first magnetic gap and the second magnetic gap is larger than the winding width of the first voice coil and the second voice coil. The vibration system is configured to vibrate between positions where at least a portion of the first voice coil and at least a portion of the second voice coil are located inside the first magnetic gap and positions where they are located inside the second magnetic gap. The drive unit, When the displacement detected by the displacement detection unit indicates that at least a predetermined proportion of the first voice coil is located inside the first magnetic gap, the first voice coil is driven using a drive signal of the first polarity; when the displacement detected by the displacement detection unit indicates that a predetermined proportion of the first voice coil is located inside the second magnetic gap, the first voice coil is driven using a drive signal of the second polarity, wherein the second polarity is the opposite of the first polarity. When the displacement detected by the displacement detection unit indicates that at least a predetermined proportion of the second voice coil is located inside the first magnetic gap, the second voice coil is driven using a drive signal of the first polarity; when the displacement detected by the displacement detection unit indicates that at least a predetermined proportion of the second voice coil is located inside the second magnetic gap, the second voice coil is driven using drive signals of both the first and second polarities.

3. The audio system according to claim 2, characterized in that, Within a first range of displacement of the vibration system, both the portions of the first voice coil and the second voice coil exceeding a predetermined proportion are located inside the first magnetic gap; within a second range of displacement of the vibration system, both the portions of the first voice coil and the second voice coil exceeding a predetermined proportion are located inside the second magnetic gap. The drive unit, When the displacement detected by the displacement detection unit indicates that the portion of the first voice coil and the portion of the second voice coil that are above a predetermined proportion are both located inside the first magnetic gap, the first voice coil and the second voice coil are driven using a drive signal of the first polarity; when the displacement detected by the displacement detection unit indicates that the portion of the first voice coil and the portion of the second voice coil that are above a predetermined proportion are both located inside the second magnetic gap, the first voice coil and the second voice coil are driven using a drive signal of the second polarity.

4. The audio system according to claim 3, characterized in that, The drive unit, When the displacement detected by the displacement detection unit indicates that the portion of the first voice coil that is above the specified proportion is neither inside the first magnetic gap nor inside the second magnetic gap, the driving of the first voice coil is stopped. When the displacement detected by the displacement detection unit indicates that the portion of the second voice coil that is above the specified proportion is neither inside the first magnetic gap nor inside the second magnetic gap, the driving of the second voice coil is stopped.

5. The audio system according to claim 2, 3 or 4, characterized in that, The portion exceeding a predetermined percentage of the first voice coil is the portion of the first voice coil exceeding n%, and the portion exceeding a predetermined percentage of the second voice coil is the portion of the second voice coil exceeding n%, where n > 0.

6. The audio system according to claim 2, characterized in that, When the upper half of the first voice coil is located within the lower part of the first magnetic gap, the lower half of the second voice coil is located within the upper part of the second magnetic gap.

7. The audio system according to claim 6, characterized in that, The winding width of the first voice coil and the second voice coil is set to L, and the axial spacing between the first voice coil and the second voice coil is set to 0.5L.

8. The audio system according to claim 7, characterized in that, The axial length of the first magnetic gap and the second magnetic gap is 1.5L.

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