JP5078850B2 - Flat speaker - Google Patents

Description

  The present invention relates to a flat speaker.

The flat speaker includes a rear magnet (back permanent magnet plate), a front magnet (front permanent magnet plate), and a case covering them. These permanent magnet plates are formed by alternately forming different belt-shaped magnetic poles at regular intervals.
Further, a voice coil made of a meandering conductor pattern is formed on the diaphragm at a position facing a so-called magnetized neutral zone in a gap portion between different magnetic poles of the permanent magnet plate.
When a current (audio signal) flows through the voice coil formed on the diaphragm, the multi-polar magnetization pattern of the voice coil and the sheet magnet (permanent magnet plate) acts electromagnetically, and according to Fleming's left-hand rule, The flexible substrate (diaphragm) generates sound vibration, and the generated sound vibration is radiated to the outside through a sound radiation hole formed in the permanent magnet plate and the case (see Patent Document 1).
A flexible substrate-like diaphragm is often a flexible structure, unlike a rigid diaphragm mounted on a cone or dome. Such a diaphragm becomes a film-like vibrating body, and natural vibration occurs from a low frequency and vibrates in a specific mode (a state having a non-uniform displacement distribution on the diaphragm surface). For example, the displacement at the lowest-order primary resonance has a distribution in which the displacement decreases as the central portion reaches the fixed end of the outer peripheral portion at the maximum.
As a countermeasure against this, in some cases, a damping tape is applied or coated on the diaphragm surface in order to suppress displacement. By joining a narrow damping tape to the housing structure so as to divide the diaphragm, the length of the vibration system can be partially shortened, suppressing the natural vibration and reducing the amplitude, There is an effect of preventing the permanent magnet plate from being touched. Such a damping tape is applied to the diaphragm surface evenly even if it is affixed at equal intervals or coated, so that a uniform load state is also applied to the diaphragm.

Japanese Patent No. 3192372

  By sticking the damping tape as described above, the diaphragm can be divided to suppress vibration. However, in practice, when a mode (displacement distribution) occurs on the diaphragm, for example, in the case of vibration in the primary mode, the operating range of the central portion becomes larger than the end. For this reason, when the damping tape is evenly applied, the force applied to the damping tape in the center is greater than that of the damping tape at the end, and the effect of suppressing natural vibration is reduced, resulting in partial amplitude. However, there is a problem that abnormal noise is generated when the diaphragm touches the permanent magnet plate.

  The present invention has been made to solve the above-described problems. A damping tape is attached so that each of the divided vibration systems vibrates in the same manner, and the effect of suppressing the natural vibration is improved. Therefore, an object is to obtain a flat speaker having a flat frequency characteristic while suppressing the generation of abnormal noise.

  In the flat speaker according to the present invention, a plate-like permanent magnet in which different magnetic strips are formed at regular intervals, and a conductor disposed at a position where the gaps between the different magnetic poles of the permanent magnet are opposed to each other are formed. In a flat speaker comprising a diaphragm, a tape attached so as to divide the surface of the diaphragm, and a frame supporting the permanent magnet, the diaphragm and the tape, a virtual dividing point on the diaphragm is set, and a virtual In each virtual division section divided by the dividing point and both ends in the longitudinal direction of the diaphragm, each virtual region sandwiched between the curve at the time of displacement due to vibration of the diaphragm and the line segment at rest in a state where the tape is not attached The ratio with the mass of the tape affixed to each virtual division section is made constant.

  According to the present invention, the virtual dividing point on the diaphragm is set, and in each virtual dividing section divided by the virtual dividing point and both longitudinal ends of the diaphragm, the vibration is caused by the vibration of the diaphragm in a state where no tape is attached. Since the ratio between each virtual region sandwiched between the curve at displacement and the line segment at rest and the mass of the tape affixed to each virtual divided section is fixed, the amplitude will partially increase due to natural vibration. And noise generated by the diaphragm touching the permanent magnet can be suppressed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a flat speaker 1 according to Embodiment 1 of the present invention. FIG. 1A is a cross-sectional view showing a configuration of a flat speaker 1 according to Embodiment 1 of the present invention, and FIG. 1B is an upper magnetic field of the flat speaker 1 according to Embodiment 1 of the present invention. It is the top view which showed the diaphragm 10 surface when removing a circuit (the upper side permanent magnet 20 and the upper side frame 30a).

  As shown in FIG. 1A, the flat speaker 1 includes a diaphragm 10, a permanent magnet 20, and a frame 30, and a magnetic circuit is configured by the permanent magnet 20 and the frame 30. The frame includes an upper frame 30a and a lower frame 30b.

  As shown in FIG. 1B, the diaphragm 10 includes a base material 11 made of a thin polymer resin sheet, and conductors 12 formed in a meandering conductor pattern on both surfaces of the base material 11. . The conductor 12 having a meandering conductor pattern is formed by pressing or etching a metal foil.

  The tape 13 is a high heat-resistant non-woven tape and is longer than the width of the diaphragm 10 in the short direction. As shown in FIG. 1B, a plurality of tapes 13 are bonded with an adhesive or the like so as to divide the longitudinal direction of the diaphragm 10. Further, both ends in the longitudinal direction of the tape 13 protruding from both sides of the diaphragm 10 in the lateral direction are supported so as to be sandwiched between the frames 30.

  The permanent magnet 20 is a plate-like permanent magnet that is magnetized by changing the polarity alternately at a constant interval, and is disposed above and below the vibrating membrane 10. As shown in FIG. 1A, the permanent magnets 20 arranged in this way are bonded and fixed to the frame 30 with an adhesive or the like.

  The frame 30 has a casing structure in which a cavity is formed by combining an upper frame 30a made of a metal such as iron and a lower frame 30b, and the tape 13 is bonded to the formed cavity. The film 10 and the permanent magnet 20 are accommodated. Although not shown, the frame 30 is provided with an input terminal for supplying a drive current for the audio signal.

Here, the relationship between the conductor 12 formed on the diaphragm 10 and the permanent magnet 20 is such that the conductor 12 is disposed at a position where the different magnetic poles of the permanent magnet 20 fixed to the frame 30 face each other.
Further, as shown in FIG. 1A, circular sound emitting holes 31a and 31b are formed in the upper frame 30a and the lower frame 30b to release sound waves to the outside when the diaphragm 10 vibrates. ing. A plurality of sound emitting holes 31 a and 31 b are provided at regular intervals along a straight line portion in the longitudinal direction of the conductor 12 formed in the diaphragm 10.
The flat speaker 1 according to Embodiment 1 of the present invention is configured as described above.

  In the configuration as described above, a magnetic path between different permanent magnets 20 adjacent to each other passes in a direction crossing the linear portion of the conductor 12 formed on the vibration film 10 along the vibration film 10. Therefore, when a current is supplied to the conductor 12 formed on the vibrating membrane 10, the conductor 12 and the permanent magnet 20 are electromagnetically coupled, and an electromagnetic force in accordance with Fleming's left-hand rule is generated in the thickness direction of the diaphragm 10. Then, the diaphragm 10 vibrates in the thickness direction. Sound waves generated when the diaphragm 10 vibrates in the thickness direction are emitted to the outside through the sound emission holes 31 a and 31 b formed in the permanent magnet 20 and the frame 30.

Next, a description will be given of an attaching interval of the tape 13 attached to the surface so as to divide the diaphragm 10.
The tape 13 is affixed so that the longitudinal direction of the diaphragm 10 may be divided | segmented, as shown in FIG.1 (b). The width in the short direction of the tape 13 to be affixed here is constant regardless of the affixing position.
FIG. 2 is a diagram illustrating a displacement curve when the diaphragm 10 is stationary with the tape 13 not attached and when vibrating in the primary mode. Assuming that the diaphragm 10 receives a reaction force proportional to the air volume, the area between the displacement curve during vibration and the straight line during rest shown in FIG. 2 is all equal (S1 = S2 = S3). Thus, the dividing point on the diaphragm 10 is determined. Then, the center position of each divided section of the divided diaphragm 10 is set as the tape 13 attachment position.

  When the diaphragm 10 vibrates in the primary mode, in the diaphragm 10 before the tape 13 is attached, the displacement at the center of the diaphragm 10 is large, and the diaphragm 10 is supported at the both ends in the longitudinal direction of the diaphragm 10 supported by the frame 30. The displacement decreases as it approaches. Therefore, as shown in FIG. 1, the interval between the tapes 13 to be applied to the vicinity of the center portion of the diaphragm 10 to which a large force is applied is set narrow, and is applied to both ends in the longitudinal direction of the diaphragm 10 having a small force. The interval between the tapes 13 is set wide. Thus, by changing the tape 13 application interval according to the magnitude of the force applied at the position where the diaphragm 10 is applied, the force applied to the tape 13 applied to each position can be made uniform. .

  As described above, in the flat speaker 1 according to Embodiment 1 of the present invention, the virtual division points on the diaphragm 10 are set, and in each virtual division section divided by the virtual division points and the longitudinal ends of the diaphragm 10. The ratio between each virtual region sandwiched between the curve at the time of displacement due to vibration of the diaphragm 10 and the line segment at rest when the tape 13 is not attached and the mass of the tape 13 attached to each virtual divided section Since the width of the tape 13 in the short direction is made constant and the adhering interval of the tape 13 is adjusted, the volume pushed out by the diaphragm 10 is divided by the tape 13. And the same amplitude can be obtained with the same driving force, and a flat frequency characteristic can be obtained.

Embodiment 2. FIG.
Although the flat speaker 1 according to the first embodiment has been described with respect to the one in which the attachment interval of the tape 13 that divides the diaphragm 10 is changed so that the load applied to the mass applied to each tape 13 is constant, In the flat speaker 1 according to the second embodiment of the present invention, the tape 13 is attached at a constant interval, and the width of the tape 13 is adjusted according to the amplitude of the diaphragm 10 at each attachment position. Thus, the load applied to the mass applied to the tape 13 attached to each divided position of the diaphragm 10 is configured to be uniform. In addition, about the structure similar to the flat speaker 1 which concerns on Embodiment 1, it shall show with the same number also in a figure, and the description is abbreviate | omitted.

FIG. 3 is a diagram showing a configuration of a flat speaker 1 according to Embodiment 2 of the present invention. FIG. 3 (a) is a cross-sectional view showing a configuration of a flat speaker 1 according to Embodiment 2 of the present invention, and FIG. 3 (b) shows an upper magnetic field of the flat speaker 1 according to Embodiment 2 of the present invention. It is the top view which showed the diaphragm 10 surface when removing a circuit (the upper side permanent magnet 20 and the upper side frame 30a).
FIG. 4 is a diagram illustrating a displacement curve when the diaphragm 10 to which the tape 13 is not attached is stationary and when vibrating in the primary mode.

  As shown in FIG. 4, in each divided section, the area sandwiched between the straight line when the diaphragm 10 is stationary and the displacement curve when vibrating is S4, S5, and S6, respectively. In FIG. 4, the divided sections are set symmetrically. In addition, the width of the tape 13 to be affixed at the center position of each divided section is m4, m5, and m6, respectively. The diaphragm 10 is assumed to receive a reaction force proportional to the air volume, and the divided areas (S4, S5, S6) so that the load on the mass received by the tape 13 attached to each divided section is constant. And the width (m4 / m5 / m6) of the tape 13 affixed to the section are equal to each other (m4 / S4 = m5 / S5 = m6 / S6).

  When the diaphragm 10 vibrates in the primary mode, in the diaphragm 10 before the tape 13 is attached, the displacement at the center of the diaphragm 10 is large, and the diaphragm 10 is supported at the both ends in the longitudinal direction of the diaphragm 10 supported by the frame 30. The displacement decreases as it approaches. Therefore, as shown in FIG. 3, the width of the tape 13 to be applied near the center of the vibrating membrane 10 to which a large force is applied is set wide, and the tape to be applied to both ends in the longitudinal direction of the vibrating membrane 10 having a small force. The width of 13 is set narrow. Thus, by changing the width of the tape 13 according to the magnitude of the force applied at the position where the diaphragm 10 is applied, the force applied to the tape 13 applied to each position can be made uniform.

  As described above, in the flat speaker 1 according to Embodiment 2 of the present invention, the virtual division points on the diaphragm 10 are set, and in each virtual division section divided by the virtual division points and the longitudinal ends of the diaphragm 10. The ratio between each virtual region sandwiched between the curve at the time of displacement due to vibration of the diaphragm 10 and the line segment at rest when the tape 13 is not attached and the mass of the tape 13 attached to each virtual divided section In order to make each constant, the interval between the tapes 13 is made constant, and the width in the short direction of the tape 13 is adjusted, so that the volume pushed out by the diaphragm 10 is divided by the tape 13. It becomes constant in the section, the same amplitude is obtained with the same driving force, and a flat frequency characteristic can be obtained.

  In Embodiments 1 and 2 of the present invention, the tape 13 attached to the diaphragm 10 is a non-woven tape. Acetate tape, cloth tape, paper tape or the like may be used. Moreover, it is preferable that these tapes 13 are a material with high heat resistance at least the part which contacts the conductor 12 which becomes high temperature when energized.

  In the first embodiment of the present invention, the vibration plate 10 is divided using the six tapes 13. However, the present invention is not limited to this, and the vibration film 10 is attached according to the amplitude of the vibration film 10. The number of tapes 13 to be attached is changed.

It is a figure which shows the structure of the planar speaker which concerns on Embodiment 1 of this invention. It is the figure which showed the displacement curve at the time of the vibration at the time of the stationary state of the diaphragm 10 to which the tape 13 is not affixed, and a primary mode. It is a figure which shows the structure of the planar speaker which concerns on Embodiment 2 of this invention. It is the figure which showed the displacement curve at the time of the vibration at the time of the stationary state of the diaphragm 10 to which the tape 13 is not affixed, and a primary mode.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Planar speaker, 10 Diaphragm, 11 Base material, 12 Conductor, 13 Tape, 20 Permanent magnet, 30 frame, 30a Upper frame, 30b Lower frame, 31a, 31b Sound emission hole.

Claims (3)

A plate-like permanent magnet in which different magnetic poles in a strip shape are formed at regular intervals;
A diaphragm formed with a conductor disposed at a position facing a gap portion between different magnetic poles of the permanent magnet;
A tape attached to divide the surface of the diaphragm;
A frame for supporting the permanent magnet, the diaphragm and the tape;
In a flat speaker comprising
When a virtual dividing point on the diaphragm is set, and the virtual dividing section is divided by the virtual dividing point and both ends in the longitudinal direction of the diaphragm, the displacement due to vibration of the diaphragm without the tape being attached A flat speaker characterized in that the ratio between each virtual region sandwiched between the curved line and the stationary line segment and the mass of the tape attached to each virtual divided section is constant. A plate-like permanent magnet in which different magnetic poles in a strip shape are formed at regular intervals;
A diaphragm formed with a conductor disposed at a position facing a gap portion between different magnetic poles of the permanent magnet;
A tape attached to divide the surface of the diaphragm;
A frame for supporting the permanent magnet, the diaphragm and the tape;
In a flat speaker comprising
The vibration in which the width in the short direction of the tape is constant, and the area sandwiched between the curve at the time of displacement by the vibration of the vibration plate and the line segment at rest is fixed even when the tape is not attached. A flat speaker characterized in that a dividing point on a plate is determined, and a center position of each dividing section divided by the dividing point and both ends of the diaphragm in the longitudinal direction is set as a tape attaching position. A plate-like permanent magnet in which different magnetic poles in a strip shape are formed at regular intervals;
A diaphragm formed with a conductor disposed at a position facing a gap portion between different magnetic poles of the permanent magnet;
A tape attached to divide the surface of the diaphragm;
A frame for supporting the permanent magnet, the diaphragm and the tape;
In a flat speaker comprising
The tape is attached at a constant interval, and is divided by the vibration of the diaphragm in a state where the tape is not attached in each of the divided sections divided by the intermediate position between the adjacent tapes and both longitudinal ends of the diaphragm. A flat speaker characterized in that the width of the tape is such that the ratio between the area sandwiched between the curve at displacement and the line segment at rest and the mass of the tape attached to each divided section is constant.

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