JP2009147547A - Circular plate type speaker - Google Patents

Circular plate type speaker Download PDF

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JP2009147547A
JP2009147547A JP2007321083A JP2007321083A JP2009147547A JP 2009147547 A JP2009147547 A JP 2009147547A JP 2007321083 A JP2007321083 A JP 2007321083A JP 2007321083 A JP2007321083 A JP 2007321083A JP 2009147547 A JP2009147547 A JP 2009147547A
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diaphragm
circular
diameter
circular flat
flat plate
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JP2007321083A
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JP4963106B2 (en
Inventor
Yuji Kotani
Hiroki Ohata
広樹 大畑
雄司 小谷
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Foster Electric Co Ltd
フォスター電機株式会社
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Abstract

PROBLEM TO BE SOLVED: To achieve a thin and light weight capable of smoothing a sound pressure frequency characteristic in a full range by suppressing the generation of a nodal circle and a nodal diameter in a resonance mode of a divided vibration over a desired frequency band by driving the entire surface of a circular flat diaphragm. Providing a circular flat plate speaker.
A plurality of small circular voice coils arranged at equal intervals on a concentric circle having a smaller diameter than a circular diaphragm and one small circular voice coil arranged at the center of the diaphragm are attached to one side of the diaphragm, and each voice A plurality of thin magnetic circuits that form a magnetic gap into which a coil can be inserted are attached to the inner surface of a frame that holds a diaphragm via an edge, and the diameter of the concentric circle is between the outer annular portion and the inner circular portion of the concentric circle. A circular flat speaker with a uniform arrangement density of all voice coils.
[Selection] Figure 1

Description

  The present invention relates to a circular flat plate type speaker, and more particularly to a full range speaker using a circular flat plate type or a so-called disc-shaped diaphragm and having a circular flat plate type as a whole.

  Conventionally, rectangular or elliptical flat plate diaphragms are mainly used as diaphragms for flat plate or thin speakers. High-efficiency drive systems using voice coils and magnetic circuits to drive these diaphragms entirely. Various proposals and trials have been made on how to achieve this while adapting to the flat plate type and thin configuration of the speaker, but no reliable proposal has been made for the entire drive system of the circular flat plate diaphragm. .

  The ideal drive for a circular flat plate diaphragm is to vibrate so that almost the entire surface of the diaphragm performs piston vibration. For example, a relatively small-diameter voice coil used in a normal cone-type speaker is driven by a circular flat plate vibration. When driven by being concentrically positioned in the center of the plate and increasing the frequency, the piston vibration disappears at the frequency of the resonance mode in which a circular node due to divided vibration, that is, a nodal circle is generated. Since this resonant mode occurs at a relatively low frequency, this configuration is not suitable for speakers intended for the full range.

  According to Patent Document 1 shown below as a conventional example, in a speaker using a circular flat plate-like diaphragm, the outer peripheral end of the drive cone coupled with the bobbin carrying the voice coil at the inner peripheral end is connected to the circular flat plate-like diaphragm. When coupled to the position of the nodal circle generated by the primary resonance and driving the diaphragm in combination with the magnetic circuit, the primary resonance is eliminated and the nodal circle does not occur, but if the frequency is further increased, the secondary resonance Can not cope with the associated circle. In other words, when the circular diaphragm is driven in the node of the primary resonance, it is possible to reproduce from the low frequency band to the frequency at which the secondary resonance occurs, but it is impossible to reproduce the frequency band beyond that.

As a solution to this problem, the other ends of the two coil bobbins having a large diameter and a small diameter, each having one end fixed to the nodal part generated by the primary resonance and the nodal part generated by the secondary resonance of the circular flat plate-like diaphragm, respectively. In addition, a large-diameter voice coil and a small-diameter voice coil are provided, and these voice coils are combined in a magnetic circuit formed by combining magnets having anisotropy in the radial direction. A configuration has been proposed in which a circular flat plate-like diaphragm is driven at two node portions of primary resonance and secondary resonance.
Japanese Patent Laid-Open No. 4-115698

  However, the vibration node generated in the resonance mode is not only a circular node circle, but also a node diameter generated in the diameter direction of the diaphragm according to the frequency, and Patent Document 1 does not show a measure for this node diameter. In addition, as described above, when two voice coils having a large diameter and a small diameter are driven by a magnetic circuit having two magnetic gaps, resonance of split vibration that generates a nodal circle by primary resonance and secondary resonance. Although the mode will be suppressed, even if it is a large-diameter voice coil, the magnetic circuit that drives it will have a huge size, and if you add a small-diameter one, it will become a huge weight, All the surrounding structures including the above are also increased in size, which is not only disadvantageous in terms of downsizing the speaker, particularly in terms of thickness and weight, but also in terms of manufacturing cost.

  Therefore, the present invention is a divided vibration that changes in almost all sound ranges by driving a circular plate-shaped diaphragm with a small voice coil and magnetic circuit from a general low-frequency range to a high-frequency range of a speaker using a circular plate-shaped diaphragm. It is an object of the present invention to provide a circular flat plate type speaker that vibrates the node with high efficiency, thereby suppressing the resonance mode, and enabling the entire driving of the diaphragm in the full range.

The means for solving the first problem according to the present invention includes a circular flat plate-like diaphragm supporting the voice coil on one side and a circular flat plate-like face facing one side of the diaphragm including a magnetic gap facing the voice coil. In a circular flat-plate speaker consisting of a magnetic circuit and a frame that holds the periphery of the diaphragm at the outer periphery via an edge and supports the magnetic circuit on the inner surface, the voice coils are equally spaced on a concentric circle having a smaller diameter than the diaphragm A plurality of small circular voice coils and one small circular voice coil positioned at the center of the diaphragm, and the concentric diameter is such that the arrangement density of the voice coils in the diaphragm is outside the concentric circles. The annular portion and the inner circular portion are set to equal values.
The second problem-solving means of the present invention is that a plurality of voice coils on a concentric circle are arranged at equal intervals with a central angle of 72 °, and the diameter of the concentric circle is 70 to 80% of the diameter of the diaphragm. Features.
The third problem-solving means of the present invention is characterized in that the concentric voice coil and the voice coil located at the center of the diaphragm have the same diameter.

The action of the first problem solving means according to the present invention is that all of the plurality of voice coils arranged at equal intervals on the concentric circles in the diaphragm can be changed in the natural vibration in the entire frequency band of the circular flat diaphragm. The concentric outer ring part that arranges a plurality of voice coils with effective driving for the nodal circle and nodal diameter of the split vibration, and the voice coil arranged at the center of the diaphragm prevents the nodal occurrence of the central part in all bands By setting the diameter of the concentric circles so that the density of the voice coils in the concentric circle inner circular portion where one voice coil is arranged at the center is equalized, uniform piston vibrations on the entire diaphragm surface can be obtained. Make it possible.
The operation of the second problem solving means according to the present invention is to drive the five nodal diameter portions in the resonance mode generated in the high frequency band by setting the five concentric voice coils at equal intervals, and in the center. It is possible to eliminate the occurrence of a node in the central portion by one arranged voice coil.
The operation of the third problem solving means according to the present invention is to equalize the arrangement density by making the diameters of all the voice coils to be used the same, thereby enabling equal driving at all the arrangement positions on the diaphragm. This makes it easy to achieve equal driving with respect to the nodes at predetermined positions.

  In order to drive a circular flat plate-like diaphragm used in a circular flat plate type loudspeaker over the full range up to 15 kHz, substantially all of the nodal circles and nodal diameters of the resonance mode of the divided vibration that changes with the vibration frequency are removed. A plurality of voice coils corresponding to the number of node diameters of resonance modes in a desired frequency band, from the viewpoint that it is advantageous to disperse and arrange a plurality of small and circular voice coils at an equal density Are arranged at equal intervals on a concentric circle in the diaphragm, and in particular, the generation of the node diameter of the desired frequency band is suppressed, and one voice coil is arranged at the center where the nodes are commonly generated in all frequency bands. Contributes to the suppression of nodal diameter generation in the frequency band. By setting the diameter of the concentric circles to a value that equalizes the arrangement density of the voice coils in the outer circular part and inner circular part of the concentric circles according to the set number of multiple voice coils on the concentric circles, All the voice coils placed in, suppress the generation of nodal circles in the full range.

First, referring to FIG. 3 to FIG. 10, a material having a Young's modulus of 2 GPa and a specific gravity of 0.27 gr / cm 3 that is generally used as a diaphragm is a circular flat diaphragm having a diameter of 140 mm and a thickness of 4 mm. Based on the natural vibration mode when oscillating at a frequency that changes up to 15 kHz, the pattern of vibration nodes that changes with the resonance mode of the divided vibration that changes with increasing frequency is considered. In particular, in FIG. 4 (3019 Hz), one circular node, that is, a node circle a (circular dark colored portion in the central portion in the monochrome view) is seen, and in FIG. 6 (6836 Hz), one nodal circle and one diameter. The node of the direction, that is, the node diameter b is one node circle a and two node diameters b in FIG. 9 (11474 Hz), and two node circles a in FIG. 10 (12751 Hz), whereas FIG. 3 (1808 Hz). ), FIG. 5 (4173 Hz), FIG. 7 (7282 Hz) and FIG. 8 (11104 Hz), 2 to 5 node diameters b appear.

  Attention is paid to the split resonance mode at 11104 Hz shown in FIG. 8, and the vibration is divided into 10 sections in the radial direction by a large number of node diameters b in the entire band. It can be seen only in the outer peripheral part, and no obvious vibration is seen in the central part surrounding the central node. Therefore, in order to drive the entire surface of the circular flat diaphragm, it is effective to formulate a drive system that does not generate these multiple node diameters and the central node by a method other than the conventional large-diameter voice coil and magnetic circuit. it is conceivable that.

  1 and 2 show an embodiment of a circular flat speaker according to the present invention. FIG. 1 is a plan view of the inner surface of a circular flat diaphragm 11 used in the circular flat speaker 10. FIG. It is sectional drawing of the speaker which follows the -A line. In the drawing, for example, a circular plate-like diaphragm 11 made of a synthetic resin material or a pulp material having a Young's modulus and specific gravity as described above is an outer periphery of a disk-shaped dish-shaped frame 12 having a shallow U-shaped cross section made of, for example, a metal plate. The wall is elastically supported via an annular edge 13 made of an elastic material. As a feature of the present invention, a plurality of small-diameter cylindrical voice coils V1 to Vn are attached to the inner surface side of the diaphragm 11, and magnetic gaps having diameters into which the voice coils V1 to Vn can be inserted are respectively formed on the inner bottom surface of the frame 12. A plurality of small-diameter thin magnetic circuits M1 to Mn to be formed are attached to the voice coils V1 to Vn so as to face each other.

  In this embodiment, as shown in FIG. 1, five radial radius lines 14 that divide the circular diaphragm 11 into five equal parts in the radial direction at a central angle of 72 degrees, and a radius r set as will be described later. The sum of five voice coils V1 to V5 on the concentric circle 15 centered at five intersections with the concentric circle 15 and one voice coil V6 centered on the center point 0 of the diaphragm Six voice coils are attached to the inner surface of the diaphragm. These voice coils V1 to V6 are desirably bonded in a cylindrical shape directly to the diaphragm surface with an adhesive at one end edge, which is advantageous in terms of reducing the thickness and weight of the speaker 10. Of course, it is good also as a structure attached via a coil bobbin. Further, it is advantageous that all of the voice coils V1 to V6 have the same diameter, and a diameter substantially one-tenth of the diameter of the diaphragm 11 is sufficiently effective.

  Similarly, the magnetic circuits M1 to Mn are magnetic circuits M1 to M5 (only M3, M5, and M6 are shown in FIG. 2) corresponding to the five voice coils V1-V5 on the concentric circle 15 of the diaphragm 11, and the diaphragm. A total of six magnetic circuits M6 corresponding to one voice coil V6 located at the center point 0 of 11 are fixed to the inner bottom surface of the frame 12. FIG. 2 shows the magnetic circuits M1 to M6 as a voice coil in an annular magnetic gap formed between a pole piece outer peripheral surface and a yoke peripheral wall inner surface by sandwiching a disk-shaped magnet between a center pole piece and a plate-shaped yoke. However, the present invention is not limited to this type, and any other type may be used as long as it achieves substantially the same drive efficiency and space efficiency in combination with a circular small voice coil. .

  The five radiation radius lines 14 for arranging the combinations of the voice coils V1 to V5 and the magnetic circuits M1 to M5 correspond to the radius portions of the five node diameters b described above with reference to FIG. 8, and the vibration pattern is rotationally moved. Even then, since the distance between the node diameters does not change, driving of the diaphragm 11 by the voice coils V1 to V5 at these five fixed positions is combined with driving by the voice coil V6 located at the center, so This corresponds to driving the diaphragm at the node diameter. Therefore, the peak dip that normally occurs in the midrange (around 11 kHz) is suppressed. The five nodal diameter drives are also effective in suppressing the occurrence of a small number of nodal diameters at other frequencies from the low range to the high range.

  Regarding the arrangement positions of the five voice coils V <b> 1 to V <b> 5 arranged at equal intervals on the concentric circle 15 and the voice coil V <b> 6 arranged at the center, it is desirable that the arrangement density be uniform with respect to the entire surface of the diaphragm 11. For this purpose, the distribution density of the voice coils inside and outside the concentric circles should be matched with the area ratio of the diaphragms inside and outside the concentric circles. That is, the radius or diameter of the concentric circle in the diaphragm 11 is set as such.

Regarding the distribution density of the voice coils, assuming that the value of each voice coil is 1.0, (0.5 × 5) + 1.0 = 3.5 is substantially inside the concentric circle, and 0.5 is outside. There will be a voice coil of x5 = 2.5. Therefore, if the radius of the diaphragm is R and the radius of the concentric circle is r, the area ratio between the inner side and the outer side of the concentric circle is
πr 2 : π (R 2 −r 2 ) = 3.5: 2.5
From this, if the ratio of r to R is calculated,
r / R = √ (7/12) ≒ 0.764
It becomes. That is, the radius or diameter of the concentric circle 15 may be set to 70 to 80% of the radius or diameter of the diaphragm 11.

  The resonance mode of the split vibration of the circular plate-like diaphragm changes according to conditions such as the dimensions, elastic modulus, specific gravity, etc. of the diaphragm material, and occurs even in the same frequency band as shown in FIGS. The number and position of knot circles and knot diameters are not the same. Accordingly, the number of voice coils arranged on the concentric circles is selected corresponding to the number of the most nodal diameters generated in a desired frequency band, and the concentric circle radius or the number corresponding to the sum of this number and one for the center. The diameter is calculated.

  3 to 10 are respectively the same circular flat plate diaphragm materials used in the present invention, 1,808 Hz, 3,019 Hz, 4,173 Hz, 6,836 Hz, 7,282 Hz, 11, 104 Hz, 11, The split vibration resonance mode of natural vibration at frequencies of 674 Hz and 12,751 Hz is shown.

The top view of the inner surface side which attached the voice coil of the circular flat plate-shaped diaphragm used for the circular flat plate type speaker by this invention. Sectional drawing which follows the AA line of FIG. 1 of the circular flat speaker by this invention using the diaphragm of FIG. The division vibration resonance mode of the natural vibration in the frequency of 1,808 Hz of the same circular flat plate-shaped diaphragm material used in the present invention is shown. The division vibration resonance mode of the natural vibration in the frequency of 3,019 Hz of the same circular flat plate-shaped diaphragm material used in the present invention is shown. The division vibration resonance mode of the natural vibration in the frequency of 4,173 Hz of the same circular flat plate-shaped diaphragm material used in the present invention is shown. The division vibration resonance mode of the natural vibration in the frequency of 6,836Hz of the same circular flat plate-shaped diaphragm material used in the present invention is shown. The split vibration resonance mode of natural vibration at a frequency of 7,282 Hz of the same circular flat plate-like diaphragm material used in the present invention is shown. The split vibration resonance mode of the natural vibration at a frequency of 11,104 Hz of the same circular flat plate-like diaphragm material used in the present invention is shown. The split vibration resonance mode of the natural vibration at a frequency of 11,674 Hz of the same circular flat plate vibration plate material used in the present invention is shown. The split vibration resonance mode of natural vibration at a frequency of 12,751 Hz of the same circular flat plate vibration plate material used in the present invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Circular flat plate type speaker 11 Circular flat plate-shaped diaphragm 12 Frame 13 Edge 14 Radiation radius line 15 Concentric circle V1-V6 Voice coil M1-M6 Magnetic circuit a Nodal circle b Nodal diameter

Claims (3)

  1.   A circular flat plate-like diaphragm that supports the voice coil on one side, a circular flat plate-shaped magnetic circuit that faces a single side of the diaphragm, including a magnetic gap facing the voice coil, and an outer periphery of the diaphragm via an edge A plurality of small circular voice coils and diaphragms arranged at equal intervals on a concentric circle having a smaller diameter than the diaphragm The diameter of the concentric circle is such that the arrangement density of the voice coils in the diaphragm is equal between the outer annular portion and the inner circular portion of the concentric circle. A circular flat plate type speaker characterized by being set to
  2.   The circular flat plate type according to claim 1, wherein a plurality of voice coils on the concentric circles are five arranged at equal intervals with a central angle of 72 °, and the diameter of the concentric circles is 70 to 80% of the diameter of the diaphragm. Speaker.
  3.   The circular flat speaker according to claim 1 or 2, wherein the concentric voice coil and the voice coil located at the center of the diaphragm have the same diameter.
JP2007321083A 2007-12-12 2007-12-12 Circular flat speaker Active JP4963106B2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011015249A (en) * 2009-07-03 2011-01-20 Foster Electric Co Ltd Indirectional speaker

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56116400A (en) * 1980-02-19 1981-09-12 Matsushita Electric Ind Co Ltd Flat plate speaker
JPS56132098A (en) * 1980-03-19 1981-10-16 Matsushita Electric Ind Co Ltd Dynamic loudspeaker
JPS5834864Y2 (en) * 1979-02-09 1983-08-05
JPS63299500A (en) * 1987-05-29 1988-12-06 Hitachi Ltd Speaker
JPH04115698A (en) * 1990-08-31 1992-04-16 Matsushita Electric Ind Co Ltd Flat speaker

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5834864Y2 (en) * 1979-02-09 1983-08-05
JPS56116400A (en) * 1980-02-19 1981-09-12 Matsushita Electric Ind Co Ltd Flat plate speaker
JPS56132098A (en) * 1980-03-19 1981-10-16 Matsushita Electric Ind Co Ltd Dynamic loudspeaker
JPS63299500A (en) * 1987-05-29 1988-12-06 Hitachi Ltd Speaker
JPH04115698A (en) * 1990-08-31 1992-04-16 Matsushita Electric Ind Co Ltd Flat speaker

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011015249A (en) * 2009-07-03 2011-01-20 Foster Electric Co Ltd Indirectional speaker

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