Sound system
By combining a dual voice coil structure and a displacement estimation unit, the technical challenge of expanding the speaker travel width is solved, enabling effective driving force control over a wide range and avoiding the increase in voice coil winding width and power consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ALPS ALPINE CO LTD
- Filing Date
- 2026-01-07
- Publication Date
- 2026-07-10
AI Technical Summary
Existing technologies struggle to effectively increase the speaker's travel width while suppressing the voice coil winding width, resulting in insufficient driving force or increased power consumption.
Employing a dual voice coil structure, the voice coil position is estimated based on the magnitude of the audio signal using a displacement estimation unit. The voice coil is driven by different magnetic gaps and magnetic flux directions. Combined with a signal processing device to control the current polarity to optimize the driving force, the loudspeaker can be effectively controlled over a wide range.
While suppressing the voice coil winding width, the speaker's travel width is increased, maintaining driving force and avoiding problems such as increased weight and excessive power consumption.
Smart Images
Figure CN122372891A_ABST
Abstract
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 that sets up two magnetic gaps, an upper magnetic gap and a lower magnetic gap, with opposite magnetic flux orientations, an upper voice coil with a winding width (winding width) L, and a lower voice coil with a winding width L opposite to the upper voice coil, such that the total winding width of the lower portion of the upper voice coil in the upper magnetic gap and the upper portion of the lower voice coil in the lower magnetic gap is L, thereby obtaining a constant driving force regardless of the displacement of the speaker's vibration system (e.g., Patent Document 1).
[0003] [Existing technical documents] Patent documents Patent Document 1: Japanese Patent Application Publication No. 9-163495 Summary of the Invention
[0004] Even small-diameter loudspeakers can reproduce bass just like large-diameter loudspeakers by ensuring a large travel width.
[0005] Furthermore, increasing the stroke width requires increasing the winding width to prevent the voice coil from shifting out of control and becoming uncontrollable. However, increasing the winding width results in a smaller driving force on the voice coil compared to a voice coil with a winding width equal to the width of the magnetic gap. On the other hand, increasing the input gain of the voice coil increases the driving force, but this also increases power consumption. Additionally, increasing the winding width increases the weight of the vibrating system containing the voice coil, which is detrimental to output sound pressure levels.
[0006] Therefore, the technical problem of the present invention is to increase the travel width of the driven loudspeaker while suppressing the winding width of the voice coil.
[0007] Means for solving technical problems To address the aforementioned technical problem, the present invention provides an audio system comprising: a loudspeaker; a driver unit that drives the loudspeaker using a drive signal obtained by signal processing an input audio signal; and a displacement estimation unit.
[0008] The loudspeaker has: a first magnetic gap; a second magnetic gap that overlaps with the first magnetic gap when viewed axially; and a first voice coil and a second voice coil fixed to the resonant system of the loudspeaker vibrating in the axial direction, such that they are located inside the first magnetic gap and the second magnetic gap when viewed axially. With one axis as the top and the other as the bottom, a first magnetic gap is disposed above the second magnetic gap, separated by the axial interval. A first voice coil is disposed above the second voice coil, separated by the axial interval. The first magnetic gap propagates magnetic flux in one of the radial directions of the loudspeaker, and the second magnetic gap propagates magnetic flux in the other radial direction. The axial interval between the first magnetic gap and the second magnetic gap is larger than the winding width of the first and second voice coils. The vibration system is configured to vibrate between a position inside the first magnetic gap and a position inside the second magnetic gap for at least a portion of the first voice coil and at least a portion of the second voice coil.
[0009] In addition, the displacement estimation unit estimates the positions of the first voice coil and the second voice coil in the axial direction of the loudspeaker based on the magnitude of the input audio signal.
[0010] Furthermore, the driving unit drives the first voice coil when the position estimated by the displacement estimation unit is such that at least a predetermined proportion of the first voice coil is inside the first magnetic gap, using a driving signal whose polarity is a first direction relative to a positive audio signal. When the position estimated by the displacement estimation unit is such that at least a predetermined proportion of the first voice coil is inside the second magnetic gap, the driving unit drives the first voice coil using a driving signal whose polarity is a second direction relative to a positive audio signal, in the opposite direction to the first direction. When the position estimated by the displacement estimation unit is such that at least a predetermined proportion of the second voice coil is inside the first magnetic gap, the driving unit drives the second voice coil using a driving signal whose polarity is a first direction relative to a positive audio signal. When at least a predetermined proportion of the second voice coil is inside the second magnetic gap, the driving unit drives the second voice coil using a driving signal whose polarity is a second direction relative to a positive audio signal.
[0011] In this audio system, it is also possible 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 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 inside the second magnetic gap. In the driving unit, when the position estimated by the displacement estimation unit is 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 inside the first magnetic gap, the first voice coil and the second voice coil are driven by a driving signal whose polarity is the first direction relative to the direction of the current flowing relative to the positive audio signal. When the position estimated by the displacement estimation unit is 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 inside the second magnetic gap, the first voice coil and the second voice coil are driven by a driving signal whose polarity is the second direction relative to the direction of the current flowing relative to the positive audio signal.
[0012] Alternatively, in this case, the driving unit may stop driving the first voice coil when the portion of the first voice coil estimated by the displacement estimation unit is above the predetermined proportion and 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 portion of the second voice coil estimated by the displacement estimation unit is above the predetermined proportion and is neither inside the first magnetic gap nor inside the second magnetic gap.
[0013] Alternatively, in this case, the displacement estimation unit may establish a correspondence between each combination of an element from the set of displacement regions of the first voice coil and an element from the set of displacement regions of the second voice coil and the range of the magnitude of the audio signal. In this displacement estimation unit, the displacement regions of the first and second voice coils represented by the combinations corresponding to the range including the magnitude of the input audio signal are estimated as the positions of the first and second voice coils in the axial direction of the loudspeaker. The set of displacement regions of the first voice coil includes displacement regions in which a portion of the first voice coil at or above a predetermined proportion is located inside the first magnetic gap, displacement regions in which a portion of the first voice coil at or above a predetermined proportion is located inside the second magnetic gap, and displacement regions in which a portion of the first voice coil at or above a predetermined proportion is neither located inside the first magnetic gap nor inside the second magnetic gap. The set of displacement regions of the second voice coil includes displacement regions in which a portion of the second voice coil at or above a predetermined proportion is located inside the first magnetic gap, displacement regions in which a portion of the second voice coil at or above a predetermined proportion is located inside the second magnetic gap, and displacement regions in which a portion of the second voice coil at or above a predetermined proportion is neither located inside the first magnetic gap nor inside the second magnetic gap.
[0014] Alternatively, in the above-described audio system, the portion of the first voice coil exceeding a predetermined proportion may be the portion of the first voice coil exceeding n% (where n>0), and the portion of the second voice coil exceeding a predetermined proportion may be the portion of the second voice coil exceeding n%.
[0015] Alternatively, in the above-described audio system, when the upper half of the first voice coil is located within the lower part of the first gap, the lower half of the second voice coil is located within the upper part of the second gap.
[0016] Alternatively, in the above audio system, the winding width of the first voice coil and the second voice coil can be set to L, the axial spacing between the first voice coil and the second voice coil can be 0.5L, and the axial length of the first magnetic gap and the second magnetic gap can be 1.5L.
[0017] According to the above-described audio system, at least one of two voice coils with different axial ranges can selectively act on both the first and second magnetic gaps with different axial ranges and opposite magnetic flux orientations to drive the loudspeaker. Therefore, the winding width of the voice coil 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.
[0018] [Invention Effects] As described above, according to the present invention, it is possible to expand the travel width of the driven loudspeaker while suppressing the winding width of the voice coil. Attached Figure Description
[0019] Figure 1 This is a diagram showing the structure of an audio system according to an embodiment of the present invention.
[0020] Figure 2 This is a diagram showing the structure of a loudspeaker according to an embodiment of the present invention.
[0021] Figure 3 This is a diagram showing the positional relationship between the magnetic gap and the voice coil in an embodiment of the present invention.
[0022] Figure 4 This is a diagram showing the relationship between displacement and voice coil drive control in an embodiment of the present invention.
[0023] Figure 5 This is a diagram illustrating an example of a region representing the size of the input audio signal in an embodiment of the present invention.
[0024] Figure 6 This is a diagram illustrating an example of voice coil drive control according to an embodiment of the present invention.
[0025] Figure 7 This is a diagram illustrating an example of voice coil drive control according to an embodiment of the present invention. Detailed Implementation
[0026] The embodiments of the present invention will be described below.
[0027] Figure 1 This describes the structure of the audio system in this embodiment.
[0028] As shown in the figure, the audio system includes an audio source device 1 that outputs audio signals, a loudspeaker 2, a signal processing device 3, a first amplifier 4, and a fifth amplifier 5.
[0029] The signal processing device 3 can be configured using a DSP (Digital Signal Processor), and includes a first gain adjustment unit 31, a second gain adjustment unit 32, a first signal processing unit 33, a second signal processing unit 34, a control unit 35, and a displacement estimation unit 36.
[0030] then, Figure 2 The diagram shows the structure of speaker 2.
[0031] 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 damper 211, and a diaphragm 212.
[0032] 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 in 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 at a position separated from the first voice coil VC1 (205) below.
[0033] In addition, on the outer periphery of the yoke 202 and the voice coil frame 203, the annular second plate 208, the annular magnet 209 and the annular first plate 207 supported on the outer periphery of the base 201 are arranged in a manner that is stacked sequentially from below.
[0034] 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.
[0035] 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.
[0036] Figure 3 Figure 'a' illustrates the positional relationship between 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. (See figure 'a'.) Figure 3 As shown in Figure b, a first magnetic gap GAP1 for magnetic flux is formed between the first plate 207 and the magnetic yoke 202, and a second magnetic gap GAP2 for magnetic flux is formed between the second plate 208 and the magnetic yoke 202. Additionally, as... Figure 3 As shown in Figure c, the orientation of the magnetic flux through the first magnetic gap GAP1 and the orientation of the magnetic flux through the second magnetic gap GAP2 are opposite when viewed in a cross-section containing the axis of the speaker 2 in the plane.
[0037] The winding widths (coil length / vertical height) of the first voice coil VC1 (205) and the second voice coil VC2 (206) are equal. Furthermore, 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 larger than L, so 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. In addition, the dimensions and configurations of each part are determined such that before the lower end of the first voice coil VC1 (205) separates from the first magnetic gap GAP1 when the voice coil frame 203 moves upward, the upper end of the second voice coil VC2 (206) enters the first magnetic gap GAP1, and before the lower end of the second voice coil VC2 (206) separates from the second magnetic gap GAP2 when the voice coil frame 203 moves downward, the lower end of the first voice coil VC1 (205) enters the second magnetic gap GAP2.
[0038] In this embodiment, we will take the 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 gap between the first voice coil VC1 (205) and the second voice coil VC2 (206) is 0.5L as an example.
[0039] 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 within the first magnetic gap GAP1, and the lower half of the second voice coil VC2 (206) is located within the second magnetic gap GAP2.
[0040] Next, in the following... Figure 3 The direction of the current on the front side of the paper facing the back side (inwards) is set to positive, and it will flow from... Figure 3 The direction of the current with the back side of the paper facing the front (towards the front) 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 within the first magnetic gap GAP1, if as Figure 3 As shown in d1, a positive current flows to the first voice coil VC1 (205), thus applying an upward force to the voice coil frame 203. Similarly, as Figure 3As shown in d2, when at least a portion of the second voice coil VC2 (206) is located within 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 second voice coil VC2 (206) is located within the second magnetic gap GAP2, if a reverse 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 d4, when at least a portion of the first voice coil VC1 (205) is located in 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.
[0041] Furthermore, when a forward current flows through the first voice coil VC1 (205) and the second voice coil VC2 (206) and a reverse current flows through them, the directions of the magnetic flux generated by the first voice coil VC1 (205) and the second voice coil VC2 (206) become opposite. Additionally, when currents flow in the same direction through the first voice coil VC1 (205) and the second voice coil VC2 (206), the directions of the magnetic flux generated by the first voice coil VC1 (205) and the second voice coil VC2 (206) are the same.
[0042] 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. This allows the electromagnetic interaction between 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), and via the voice coil frame 203, a vibration corresponding to the amplitude of the reproduced sound signal can be applied to the vibrating plate 212, thereby generating a sound corresponding to the reproduced sound signal.
[0043] Additionally, return Figure 1 The displacement estimation unit 36 of the signal processing device 3 estimates the region where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located based on the audio signal output by the audio source device 1, and outputs it to the control unit 35.
[0044] Here, the region is defined as the area between the first magnetic gap GAP1, the second magnetic gap GAP2, the area between the first magnetic gap GAP1 and the second magnetic gap GAP2 (i.e., the middle), the area that is neither the first magnetic gap GAP1 nor the second magnetic gap GAP2 nor the middle, the area that is on the opposite side of the second magnetic gap GAP2 relative to the first magnetic gap GAP1, and the area that is on the opposite side of the first magnetic gap GAP1 relative to the second magnetic gap GAP2 (i.e., the outside of GAP).
[0045] The displacement estimation unit 36 estimates which of the first voice coil VC1 (205) is located within the first magnetic gap GAP1, the second magnetic gap GAP2, the middle gap, or the gap, and outputs this information to the control unit 35. Here, "the first voice coil VC1 (205) is located within the first magnetic gap GAP1" means that at least a portion of the first voice coil VC1 (205) is located within the first magnetic gap GAP1; "the first voice coil VC1 (205) is located within the second magnetic gap GAP2" means that at least a portion of the first voice coil VC1 (205) is located within the second magnetic gap GAP2; "the first voice coil VC1 (205) is located in the middle gap" means that the entire first voice coil VC1 (205) is located in the middle gap; and "the first voice coil VC1 (205) is located outside the gap" means that the entire first voice coil VC1 (205) is located outside the gap.
[0046] Similarly, regarding the second voice coil VC2 (206), it is estimated that the second voice coil VC2 (206) is located within the first magnetic gap GAP1, within the second magnetic gap GAP2, in the middle, or outside the gap, and this is output to the control unit 35. Here, the second voice coil VC2 (206) being located within the first magnetic gap GAP1 means that at least a portion of the second voice coil VC2 (206) is located within the first magnetic gap GAP1; the second voice coil VC2 (206) being located within the second magnetic gap GAP2 means that at least a portion of the second voice coil VC2 (206) is located within the second magnetic gap GAP2; the second voice coil VC2 (206) being located in the middle means that the entire second voice coil VC2 (206) is located in the middle; and the second voice coil VC2 (206) being located outside the gap means that the entire second voice coil VC2 (206) is located outside the gap.
[0047] Next, the first gain adjustment unit 31 adjusts the gain of the audio signal input from the audio source device 1 with the gain set by the control unit 35 and outputs it to the first signal processing unit 33. The second gain adjustment unit 32 adjusts the gain of the audio signal input from the audio source device 1 with the gain set by the control unit 35 and outputs it to the second signal processing unit 34.
[0048] The first signal processing unit 33 outputs the audio signal input from the first gain adjustment unit 31 to the first amplifier 4, and performs processing to switch the presence or absence of the audio signal output to the first amplifier 4 according to the control unit 35, and to switch the polarity of the audio signal output to the first amplifier 4 according to the control unit 35. Similarly, the second signal processing unit 34 outputs the audio signal input from the second gain adjustment unit 32 to the second amplifier, and performs processing to switch the presence or absence of the audio signal output to the second amplifier according to the control unit 35, and to switch the polarity of the audio signal output to the second amplifier according to the control unit 35.
[0049] The first amplifier 4 amplifies the audio signal input from the first signal processing unit 33 with a predetermined gain and outputs it to the first voice coil VC1 (205) of the speaker 2. The second amplifier amplifies the audio signal input from the second signal processing unit 34 with the same gain as the first amplifier 4 and outputs it to the second voice coil VC2 (206) of the speaker 2.
[0050] The control of the first signal processing unit 33 and the second signal processing unit 34 by the control unit 35 will be described below.
[0051] The control unit 35 controls the switching of the presence or absence of the output of the first signal processing unit 33 and the second signal processing unit 34, as well as the switching of the positive or negative polarity of the output audio signal, based on the area where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located, as estimated by the displacement estimation unit 36.
[0052] Here, Figure 4 Figure a shows the positional relationship of the vibration system of speaker 2, including displacement ΔZ, first voice coil VC1 (205), second voice coil VC2 (206), first magnetic gap GAP1, second magnetic gap GAP2, the middle area, and the area outside GAP.
[0053] In addition, Figure 4 Figure b1 shows the region where the first voice coil VC1 (205) controlled by the control unit 35 is located, the presence or absence of the output from the first signal processing unit 33 to the first amplifier 4, and the relationship between the positive and negative polarities of the audio signal output to the first amplifier 4. However, the positive and negative polarities of the audio signal output to the first amplifier 4 are indicated by the direction of the current flowing in the first voice coil VC1 (205) when the value of the audio signal input to the first signal processing unit 33 is positive. In addition, in Figure 4Figure b2 shows the region where the second voice coil VC2 (206) controlled by the control unit 35 is located, the presence or absence of the output from the second signal processing unit 34 to the second amplifier, and the relationship between the positive and negative polarities of the audio signal output to the second amplifier. However, the positive and negative polarities of the audio signal output to the second amplifier are indicated by the direction of the current flowing in the second voice coil VC2 (206) when the value of the audio signal input to the second signal processing unit 34 is positive.
[0054] 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.
[0055] As shown in the figure, the control unit 35 controls the positive and negative polarities of the audio signal output by the first signal processing unit 33 to the first amplifier 4, so that when the first voice coil VC1 (205) is located in the first magnetic gap GAP1, when the value of the audio signal input to the first signal processing unit 33 is positive, the current flows through the first voice coil VC1 (205) in the positive direction, and when the first voice coil VC1 (205) is located in the second magnetic gap GAP2, when the value of the audio signal input to the first signal processing unit is positive, the current flows through the first voice coil VC1 (205) in the reverse direction.
[0056] In addition, when the first voice coil VC1 (205) is in the middle or outside the gap, the control unit 35 controls the output of the first signal processing unit 33 to the first amplifier 4 to stop the output to the first amplifier 4.
[0057] In addition, the control unit 35 controls the positive and negative polarities of the audio signal output by the second signal processing unit 34 to the second amplifier, so that when the second voice coil VC2 (206) is located within the second magnetic gap GAP2, when the value of the audio signal input to the second signal processing unit 34 is positive, the current flows through the second voice coil VC2 (206) in the opposite direction, and when the second voice coil VC2 (206) is located within the first magnetic gap GAP1, when the value of the audio signal input to the second signal processing unit 34 is positive, the current flows through the second voice coil VC2 (206) in the positive direction.
[0058] In addition, when the second voice coil VC2 (206) is in the middle or outside the gap, the control unit 35 controls the output of the second signal processing unit 34 to the second amplifier to stop the output to the second amplifier.
[0059] As a result, the displacement of speaker 2 is located at Figure 4When within the range BZ of a, 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 35 shown in b1 and b2 can apply force to the voice coil frame 203 in an appropriate direction relative to the positive or negative of the audio signal output by the audio source device 1, so that the vibration system of the loudspeaker 2 vibrates. The range BZ is the range between the position where the lower end of the first voice coil VC1 (205) 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.
[0060] 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).
[0061] 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 structure is vertically symmetrical, asymmetrical deformation is less likely to occur.
[0062] return Figure 1 The control unit 35 controls the gain of the first gain adjustment unit 31 and the gain of the second gain adjustment unit 32 so that the required driving force of the first voice coil VC1 (205) and the second voice coil VC2 (206) is obtained for the audio signal output by the sound source device 1 in the above structure.
[0063] Next, the estimation operation performed by the displacement estimation unit 36 based on the audio signal output by the audio source device 1, and the estimation of the region where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located, will be explained.
[0064] like Figure 5 As shown, in the displacement estimation unit 36, the range of the nine regions A1 to A9, which represent the magnitude of the audio signal output by the sound source device 1, is pre-set to correspond with the regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located. Here, each region is pre-determined and set as follows.
[0065] Region A1: When the audio signal S with the level in region A1 is controlled by the control unit 35 as described above (control of the gain of the first gain adjustment unit 31 and the second gain adjustment unit 32, switching of the presence or absence of the output of the first signal processing unit 33 and the second signal processing unit 34, and switching of the positive and negative polarities of the output audio signal), the regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located outside the GAP are established as corresponding regions.
[0066] Region A2: When the audio signal S with the level in region A2 is controlled by the control unit 35 as described above, it is a region where the first voice coil VC1 (205) is outside the GAP and the second voice coil VC2 (206) is inside the first magnetic gap GAP1. The regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located are established to correspond.
[0067] Region A3: When the audio signal S with the level in region A3 is controlled by the control unit 35 as described above, it is the region between the first voice coil VC1 (205) and the second voice coil VC2 (206) in the first magnetic gap GAP1, and the regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located are established to correspond.
[0068] Region A4: When the audio signal S with the level in region A4 is controlled by the control unit 35 as described above, it is a region in which the first voice coil VC1 (205) is in the first magnetic gap GAP1 and the second voice coil VC2 (206) is in the middle. The regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located are established to correspond.
[0069] Region A5: When the audio signal S with the level in region A5 is controlled by the control unit 35 as described above, it is a region in which the first voice coil VC1 (205) is in the first magnetic gap GAP1 and the second voice coil VC2 (206) is in the second magnetic gap GAP2. The regions in which the first voice coil VC1 (205) and the second voice coil VC2 (206) are located are established to correspond.
[0070] Region A6: When the audio signal S with the level in region A6 is controlled by the control unit 35 as described above, it is a region in which the first voice coil VC1 (205) is in the middle and the second voice coil VC2 (206) is in the second magnetic gap GAP2. The regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located are established to correspond.
[0071] Region A7: When the audio signal S with the level in region A7 is controlled by the control unit 35 as described above, it is the region between the first voice coil VC1 (205) and the second voice coil VC2 (206) in the second magnetic gap GAP, and the regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located are established to correspond.
[0072] Region A8: When the audio signal S with the level in region A8 is controlled by the control unit 35 as described above, the region where the first voice coil VC1 (205) is inside the second magnetic gap GAP and the second voice coil VC2 (206) is outside the GAP is established to correspond to the region where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located.
[0073] Region A9: When the audio signal S with the level in region A1 is controlled by the control unit 35 as described above, the regions outside the gap between the first voice coil VC1 (205) and the second voice coil VC2 (206) are established to correspond to each other.
[0074] Then, the displacement estimation unit 36 detects which region the magnitude of the audio signal output by the sound source device 1 is contained in, and estimates the region corresponding to the detected region as the region where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located, and outputs it to the control unit 35.
[0075] The result of the above control is that when the applied audio signal value is positive, and the current flows through the first voice coil VC1 (205) in the positive direction and through the second voice coil VC2 (206) in the negative direction, the output of the first signal processing unit 33 is as follows: Figure 6 As shown, the output of the second signal processing unit 34 is controlled as follows. Figure 3 It is controlled as shown.
[0076] That is, such as Figure 6 As shown, the output of the first signal processing unit 33 stops when the magnitude of the audio signal S output by the audio source device 1 is within regions A1 and A2, maintains the polarity of the audio signal S when it is within regions A3, A4, and A5, stops when it is within region A6, reverses the polarity of the audio signal S when it is within regions A7 and A8, and stops when it is within region A9.
[0077] In addition, such as Figure 7As shown, the output of the second signal processing unit 34 stops when the magnitude of the audio signal S output by the audio source device 1 is within region A1, reverses the polarity of the audio signal S when it is within regions A2 and A3, stops when it is within region A4, maintains the polarity of the audio signal S when it is within regions A5, A6, and A7, and stops when it is within regions A8 and A9.
[0078] In addition, in the displacement estimation unit 36, the correspondence between the ranges of the nine regions A1 to A9 preset in advance and the regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located is calculated, for example, as follows.
[0079] That is, a sensor is set up to detect the displacement ΔZ of the vibration system of the loudspeaker 2. In the displacement estimation unit 36, the area where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located is calculated based on the displacement ΔZ detected by the sensor and output to the control unit 35. Under the control state described above in the control unit 35, a predetermined test signal (e.g., a sine wave) is output from the sound source device 1 while gradually increasing the amplitude.
[0080] Furthermore, when the combination of the regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located, calculated by the displacement estimation unit 36, changes, the magnitude of the test signal is correspondingly stored in relation to the combination of the detected regions, the regions corresponding to the combination of the detected regions, and the boundaries of the regions corresponding to the combination of regions adjacent to the region in the direction where the absolute value of the audio signal magnitude is smaller. As for the magnitude of the test signal, the maximum value of the test signal is used when the combination of the detected regions corresponds to the magnitude of a positive audio signal, and the minimum value is used when the combination of the detected regions corresponds to the magnitude of a negative audio signal.
[0081] Then, based on the boundaries between the regions as determined above, the ranges of the nine regions A1 to A9 are determined to correspond to the regions where the first voice coil VC1 (205) and the second voice coil VC2 (206) are located.
[0082] The embodiments of the present invention have been described above.
[0083] Here, the above implementation can also be implemented such that, in the displacement estimation unit 36, the displacement ΔX of the first voice coil VC1 (205) and the second voice coil VC2 (206) is estimated based on the magnitude of the audio signal output by the audio source device 1, and in the control unit 35, the gain of the first gain adjustment unit 31 and the gain of the second gain adjustment unit 32 are controlled based on the displacement ΔX estimated by the displacement estimation unit 36, so that... Figure 4 The vibration system's response to the audio signal is as equal as possible within the displacement range BZ shown in figure a.
[0084] [Explanation of reference numerals in the attached figures] 1…Sound source device, 2…loudspeaker, 3…signal processing device, 4…first amplifier, 5…fifth amplifier, 31…first gain adjustment unit, 32…second gain adjustment unit, 33…first signal processing unit, 34…second signal processing unit, 35…control unit, 36…displacement estimation unit, 201…base, 202…magnetic yoke, 203…voice coil frame, 204…dust cover, 205…voice coil VC2, 206…voice coil VC1, 207…first plate, 208…second plate, 209…magnet, 210…frame, 211…damper, 212…vibrating plate.
Claims
1. An audio device comprising: speaker; The driving unit drives the speaker by generating a driving signal from the input audio signal; and Displacement estimation element The loudspeaker has: A first magnetic gap and a second magnetic gap that overlaps with the first magnetic gap when viewed axially from the loudspeaker; and The first and second voice coils are fixed to the resonant system of the loudspeaker vibrating in the axial direction, such that they are located inside the first and second magnetic gaps when viewed in the axial direction. One of the axial directions is positioned above, and the other is positioned below. 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, separated by the axial interval. The first magnetic gap propagates magnetic flux in one of the radial directions of the loudspeaker, and the second magnetic gap propagates magnetic flux in the other of the radial directions. 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 displacement estimation unit estimates the axial positions of the first voice coil and the second voice coil in the loudspeaker based on the magnitude of the input audio signal. When the displacement estimation unit determines that the portion of the first voice coil, at least a predetermined proportion, is located inside the first magnetic gap, the driving unit drives the first voice coil using a driving signal whose polarity is a first direction relative to a positive audio signal; when the displacement estimation unit determines that the portion of the first voice coil, at least a predetermined proportion, is located inside the second magnetic gap, the driving unit drives the first voice coil using a driving signal whose polarity is a second direction, opposite to the first direction, relative to a positive audio signal. When the position estimated by the displacement estimation unit is such that at least a predetermined proportion of the second voice coil is inside the first magnetic gap, the driving unit drives the second voice coil using a driving signal whose polarity is the first direction relative to a positive audio signal; when at least a predetermined proportion of the second voice coil is inside the second magnetic gap, the driving unit drives the second voice coil using a driving signal whose polarity is the second direction relative to a positive audio signal.
2. The audio system according to claim 1, wherein, 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. When the displacement estimation unit determines that the portion of the first voice coil and the portion of the second voice coil that are both at a predetermined proportion or greater are located inside the first magnetic gap, the driving unit drives both the first and second voice coils using a driving signal whose polarity is the first direction relative to the direction of the current flowing relative to the positive audio signal; when the displacement estimation unit determines that the portion of the first voice coil and the portion of the second voice coil that are both at a predetermined proportion or greater are located inside the second magnetic gap, the driving unit drives both the first and second voice coils using a driving signal whose polarity is the second direction relative to the direction of the current flowing relative to the positive audio signal.
3. The audio system according to claim 2, wherein, When the position estimated by the displacement estimation unit is such that the portion of the first voice coil that is above the predetermined proportion is neither inside the first magnetic gap nor inside the second magnetic gap, the driving unit stops driving the first voice coil; when the position estimated by the displacement estimation unit is such that the portion of the second voice coil that is above the predetermined proportion is neither inside the first magnetic gap nor inside the second magnetic gap, the driving unit stops driving the second voice coil.
4. The audio system according to claim 3, wherein, In the displacement estimation unit, a correspondence is established between each combination of an element from the set of displacement regions of the first voice coil and an element from the set of displacement regions of the second voice coil and the range of audio signal magnitude. The set of displacement regions of the first voice coil is defined by the following elements: displacement regions in which a portion of the first voice coil exceeding a predetermined proportion is located inside the first magnetic gap; displacement regions in which a portion of the first voice coil exceeding a predetermined proportion is located inside the second magnetic gap; and displacement regions in which a portion of the first voice coil exceeding a predetermined proportion is neither located inside the first magnetic gap nor inside the second magnetic gap. The set of displacement regions of the second voice coil is defined by the following elements: displacement regions in which a portion of the second voice coil exceeding a predetermined proportion is located inside the first magnetic gap; displacement regions in which a portion of the second voice coil exceeding a predetermined proportion is located inside the second magnetic gap; and displacement regions in which a portion of the second voice coil exceeding a predetermined proportion is neither located inside the first magnetic gap nor inside the second magnetic gap. The displacement estimation unit estimates the displacement regions of the first and second voice coils, represented by a combination corresponding to a range including the magnitude of the input audio signal, as the positions of the first and second voice coils along the axial direction of the loudspeaker.
5. The audio system according to any one of claims 1 to 4, wherein, The portion exceeding a predetermined percentage of the first voice coil is the portion exceeding n% of the first voice coil, and the portion exceeding a predetermined percentage of the second voice coil is the portion exceeding n% of the second voice coil, where n>0.
6. The audio system according to claim 1, wherein, When the upper half of the first voice coil is located within the lower part of the first gap, the lower half of the second voice coil is located within the upper part of the second gap.
7. The audio system according to claim 6, wherein, The winding width of the first voice coil and the second voice coil is set to L, the axial spacing between the first voice coil and the second voice coil is 0.5L, and the axial length of the first magnetic gap and the second magnetic gap is 1.5L.