JP2011010189A - Board speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a board speaker configured so as to further efficiently vibrate a sound generation board, as a vibration forming mechanism as compared to prior types.SOLUTION: One end portion of a leaf spring with a magnetic circuit part being fixed in the other end portion is mounted on the surface of a sound generation board. The other end portion of the leaf spring is provided substantially in parallel with the surface of the sound generation board so as to transfer the vibration which is generated in a voice coil, in relation to the magnetic circuit part, and to a direction perpendicular to the surface of the sound generating board. Thus, the effect of transferring the vibration from the voice coil to the sound generating board can be improved further.

Description

  The present invention relates to a board speaker, and in particular, can efficiently apply vibration to a sound generating board.

  As this type of board speaker, the sound generating board is vibrated by transmitting the vibration of the audible sound frequency generated in the vibration generating mechanism (also called an exciter) to the surface of the sound generating board. A structure that generates acoustic energy on the plate surface has been proposed (see Patent Document 1).

JP 2003-143690 A

  This type of board speaker vibration formation mechanism flows the voice coil through the magnetic flux of the magnetic circuit unit including the magnet and the yoke in order to electromagnetically convert it into mechanical vibration based on the electric drive signal of the audible sound frequency. Since the audio current is linked, it is desirable to efficiently generate the vibration to be transmitted to the sound generating board while supporting the relatively large gravity of the magnetic circuit unit.

  The present invention has been made in consideration of the above points, and intends to propose a board speaker that can vibrate a sound generating board more efficiently than a conventional vibration generating mechanism. is there.

  In order to solve this problem, in the present invention, in the board speaker 1 having the vibration generating unit 11 that transmits the vibration of the voice coil 26 interlinked with the magnetic flux of the magnetic circuit unit 24 to the surface of the sound generating board 2, one end portion Is attached to the surface of the sound generating board 2 and the other end is fixed to the magnetic circuit part 24. The leaf spring 12 is used to generate vibrations from the voice coil 26 and the vibration generating part 11. The other end is provided substantially in parallel with the surface 2A of the sound generating board 2 so as to transmit in a direction orthogonal to the surface 2A of the board 2.

  According to the present invention, one end of a leaf spring having a magnetic circuit portion fixed to the other end is attached to the surface of the sound generating board, and the driving force generated in the voice coil in association with the magnetic circuit portion is used for sound generation. By providing the one end of the leaf spring almost in parallel with the surface of the sound generating board so that it is transmitted in a direction perpendicular to the surface of the board, the effect of transmitting vibration from the voice coil to the sound generating board is achieved. It can be further enhanced.

It is sectional drawing which shows the board speaker by one embodiment of this invention. It is a front view which shows the leaf | plate spring of FIG. It is a basic diagram which shows the example of application to a liquid crystal television. It is a characteristic curve figure with which it uses for description of the improvement effect of a frequency characteristic. It is a characteristic curve figure which shows a comparative example. It is a front view which shows other embodiment using an I-shaped leaf | plate spring. It is a front view which shows other embodiment using a cross-shaped leaf | plate spring.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) First Embodiment In FIGS. 1 and 2, reference numeral 1 denotes a board speaker as a whole, and a vibration forming mechanism 3 is provided on the surface of the sound generating board 2.

  In the case of this embodiment, the sound generating board 2 is a back plate of a casing of a thin liquid crystal television constituting the image display device.

  The vibration forming mechanism 3 has a vibration generating portion 11 fixed to the surface of the sound generating board 2, and a tip end portion of a leaf spring 12 supporting the gravity is integrally bonded to the outer surface of the vibration generating portion 11. Yes.

  In the case of this embodiment, the leaf spring 12 is a vertically long thin plastic material having a high compliance in the thickness direction (vertical length 10 [cm], width 2 to 4 [cm], thickness 1 [ mm] or less), and the upper end portion is bent in an L shape.

  Thus, in the leaf spring 12, the vertical plate portion 12A extending in the vertical direction extends in the vertical direction substantially parallel to the sound generating board 2 and the vibration generating portion 11 is provided at the lower end portion thereof. Of the support plate portion 12B bent in a right angle direction from the upper end of the vertical plate portion 12A toward the sound generation board 2, the tip portion that abuts the sound generation board 2 is perpendicular to the sound generation board 2. The mounting plate portion 12C is formed by being bent.

  The mounting plate portion 12C is attached to the sound generating board 2 by a mounting screw 13 so that the vertical plate portion 12A extending substantially parallel to the sound generating board 2 is outside the outermost diameter of the vibration generating portion 11. As shown by the arrow a, while being attached at a position apart from the sound source, it can vibrate in a direction substantially perpendicular to the plate surface of the sound generating board 2 (referred to as the front-rear direction), and The vibration generating unit 11 is supported so as not to hang downward due to the gravity.

  Thus, when the vibration generating portion 11 vibrates in the direction perpendicular to the sound generating board 2, the leaf spring 12 has the longitudinal plate portion 12 </ b> A centered on the bent portion 12 </ b> D to the support plate portion 12 </ b> B in the front-back direction It is made to be able to vibrate.

  In the case of this embodiment, a reinforcing member 15 made of a plate-like plastic material is attached along the lower surface of the support plate portion 12B, and as a result, a bending portion serves as a vibration fulcrum in the longitudinal direction of the leaf spring 12. The position of 12D is supported so as not to fluctuate.

  The vibration generating unit 11 includes a magnetic circuit unit 24 provided with an outer yoke 22 and a plate 23 made of a magnetic material so as to sandwich an annular magnet 21 disposed substantially parallel to the sound generating board 2 from the front-rear direction. The plate 23 has an annular plate shape, whereas the outer yoke 22 has a configuration in which a cylindrical yoke portion 22B protrudes from the center position so as to pass through the annular magnet 21 and the center hole of the plate 23. .

  A voice coil 26 wound around a bobbin 25 is disposed in a region between the central hole of the plate 23 and the cylindrical yoke portion 22B of the outer yoke 22, whereby an audio current having an audible frequency flows through the voice coil 26. When this occurs, the voice coil 26 is perpendicular to the outer surface of the sound generating board 2 by interlinking with the magnetic flux of the magnetic circuit portion 24 passing through the gap between the plate 23 and the cylindrical yoke portion 22B of the outer yoke 22. It is designed to vibrate.

  A disc-like voice coil cap 27 is bonded to the inner end surface of the bobbin 25, and thus the bobbin 25, the voice coil 26 and the voice coil cap 27, on the outside based on the magnetic flux of the magnetic circuit unit 24 and the voice current of the voice coil 26. A voice coil center portion 28 that vibrates in the front-rear direction is formed along the cylindrical yoke portion 22 </ b> B of the yoke 22.

  The inner surface of the voice coil cap 27 is made of a metal or a plastic material, and is bonded to the outer surface of the vibration transmitter 32 fixed to the outer surface 2A of the sound generating board 2 by a mounting screw 31.

  Thus, when the voice coil center portion 28 vibrates in the front-rear direction by flowing from the voice current to the voice coil 26, this vibration is transmitted to the sound generating board 2 via the vibration transmitter 32.

  In the case of this embodiment, a damper 35 made of a loosely formed product made of cloth is provided between the bobbin 25 and the inner surface of the plate 23, so that the voice coil 26 and the bobbin 25 are connected to the cylindrical yoke portion 22 B of the outer yoke 22. The gap between the outer wall surface and the inner wall surface of the center hole of the plate 23 is held so as to be movable in the front-rear direction.

  A support base 37 made of a ring-like viscoelastic material (for example, a porous material such as urethane sponge) is disposed at a position surrounding the vibration transmitting element 32 on the outer surface 2A of the sound generating board 2. A support frame 38 having an umbrella bone shape as a whole is provided between the outer surface of the support base 37 and the inner surface of the plate 23.

  Thus, the annular magnet 21, the outer yoke 22, and the plate 23 that constitute the magnetic circuit portion 24 are disposed in the front-rear direction on the outer surface 2 A of the sound generating board 2 via the aggregate 38 A and the support base 37 of the support frame 38. It is supported so that it can vibrate.

  In the case of this embodiment, both ends of the voice coil 26 are led to wiring connection terminals 40 provided on the aggregate 38A of the support frame 38 and printed wiring 41 provided on the outer surface of the leaf spring 12. Wiring connection terminals 42 and 43 are provided at both ends, and by connecting a lead wire 44 between the connection terminal 40 of the voice coil 26 and the connection terminal 42 of the leaf spring 12, the voice input current is supplied to the leaf spring 12. A voice current can be supplied to the voice coil 26 by supplying it to the connection terminal 43 provided on the support plate portion 12B.

  In the above configuration, when an audio signal is given to the connection terminal 43 for inputting an audio signal, the audio signal is given to the lead wire 44 through the printed wiring 41 and the connection terminal 42 provided on the leaf spring 12. This is supplied to the voice coil 26 via the connection terminal 40 provided on the aggregate 38A of the support frame 38 of the vibration generating unit 11.

  At this time, the voice coil 26 links the supplied audio current with the magnetic flux passing through the magnetic circuit unit 24, thereby moving the voice coil center unit 28 along the cylindrical yoke portion 22 </ b> B of the outer yoke 22 to the sound generating board 2. Vibrate in a direction orthogonal to the outer surface 2A.

  This vibration is caused by the fact that the magnetic circuit section 24 is supported by the leaf spring 12 and the support base 37, so that the voice coil cap 27 receives stress from the magnetic circuit section 24 according to the voice coil 26 and is applied to the sound generating board 2. Gives you the power to strike.

  The stress acting between the voice coil 26 and the magnetic circuit unit 24 causes the leaf spring 12 to vibrate according to the magnetic circuit unit 24.

  As a result, vibrations in the high frequency region mainly occur on the voice coil 26 side, whereas vibrations in the low frequency region mainly occur on the magnetic circuit unit 24 side.

  At this time, the leaf spring 12 tries to make an arc motion in the direction of the arrow a around the bent portion 12D at the upper end of the longitudinal plate portion 12A of the leaf spring 12, but the longitudinal plate portion 12A The magnetic circuit portion 24 provided at the tip is located far from the bent portion 12D serving as a fulcrum by the length of the vertical plate portion 12A, and the vertical plate portion 12A flexibly vibrates when having high compliance. As a result, the magnetic circuit section 24 moves in a direction substantially orthogonal to the outer surface 2A of the sound generating board 2.

  Further, the annular magnet 21, the outer yoke 22 and the plate 23 constituting the magnetic circuit portion 24 have a considerable weight. However, the downward gravity is supported by the leaf spring 12 by the tensile stress. The part 24 is prevented from sagging downward.

  Thus, the flexible vibration effect due to the high compliance of the leaf spring 12 and the drooping prevention effect due to the tensile stress make it possible to effectively prevent the support base 37 and the damper 35 from being kinked during the vibration process of the voice coil center portion 28. By being able to prevent, the vibration efficiency of the voice coil center part 28 can be kept higher.

  According to the above configuration, when the voice coil center portion 28 is vibrated, the relatively heavy magnetic circuit portion 24 is supported by the leaf spring 12 provided substantially parallel to the sound generating board 2. Since the voice coil center portion 28 can be vibrated efficiently, this vibration can efficiently transmit the vibration caused by the audio current to the sound generating board 2 (in this embodiment, the casing of the liquid crystal television). Can do.

  In the case of this embodiment, as shown in FIG. 3, the liquid crystal television of the sound generation board 2 includes left and right channels at the left and right positions of the liquid crystal television screen 2B on the back plate of the housing of the liquid crystal television. Board speakers 1L and 1R are provided, and the left and right board speakers 1L and 1R transmit vibrations due to left and right channel audio signals to the casing which is the sound generating board 2, thereby liquid crystal. A user who is viewing the television screen 2B from the surface can listen to stereo sound from the entire screen 2B of the liquid crystal television.

(2) Improvement Effect on Comparative Example FIG. 4 shows an experimental result on the frequency characteristics of the board speaker 1 of FIGS. 1 and 2, and the leaf spring 12 is not provided as shown in FIG. 5 as a comparative example. In this case, an improvement effect is obtained in which the audio output is further increased with respect to the frequency characteristics of FIG.

  Incidentally, in FIG. 4, the sound output level of 100 [Hz] is increased by about 8 [dB] compared to the case of FIG.

  This means that even in the audio output, the extension of the sound in the bass part is further improved.

  It can be seen that the extension of the sound in the low sound range is based on the flexible vibration effect due to the high compliance of the leaf spring 12 and the drooping prevention effect due to the tensile stress of the leaf spring 12.

  The improvement effect in the above embodiment is considered as follows.

  In general, in a board speaker that transmits the driving force of the voice coil to the plate surface and generates acoustic energy on the plate surface, it is structurally impossible to provide a vibration transmitting portion for the plate surface at the center of gravity of the entire device, In the case of a vertical or inclined plate surface, it is inevitable that the vibration transmission force has a strong rotation mode in the direction of gravity due to the gravity of the magnetic circuit section.

  In particular, when aiming at the reproduction of heavy bass, it is necessary to increase the compliance with respect to the plate surface of the entire board speaker, and the rotation mode becomes remarkable, so a reduction in driving force due to the rotation mode is inevitable.

  In the case of a vertical or inclined plate surface, a long-time static load is applied to the viscoelastic body that creates compliance, and there is a problem that permanent deformation of the viscoelastic body due to creep or the like occurs.

  In addition, even with horizontal plate surfaces other than the vertical plate surface, the conventional method of holding a board speaker using only a viscoelastic film cannot avoid the rotational movement about the fixed surface of the viscoelastic film. There was a problem that heavy bass reproduction could not be achieved sufficiently.

  Patent Document 1 described above discloses a structure in which a viscoelastic film is connected to an outer peripheral frame at the center of gravity of a magnetic circuit so as to deal with a vertical plate surface. However, with this structure, there is no suppression effect on the rotation mode with the viscoelastic film as a fulcrum, and the generation of this rotation mode causes a reduction in the driving force of the plate surface, making it difficult to reproduce a specific frequency in the low range.

  With respect to the above-described problems, according to the above-described embodiment, the magnetic circuit portion 24 that vibrates mainly in the low frequency region is provided by the leaf spring 12 provided with the vertical plate portion 12A substantially parallel to the sound generating board 2. In addition to giving flexible vibration to the sound generating board 2 with high compliance, the occurrence of rotation mode is effectively suppressed by preventing the magnetic circuit part 24 from drooping due to the tensile stress of the leaf spring 12. As a result, a board speaker capable of efficiently transmitting vibration to the sound generating board 2 can be realized.

(3) Other Embodiments (3-1) FIG. 6 shows another embodiment, and in the case of FIG. 6, as shown in FIG. The leaf spring 12X has a configuration that is elongated in the vertical direction through the position of the vibration generating portion 11 and extends in an I shape, and the mounting plate portions 12CX1 and 12CX2 formed on the upper and lower ends thereof are the vibration generating portion 11. Is attached to the sound generating board 2 by mounting screws 13X1 and 13X2 at positions having the same length in the vertical direction.

  Thus, the vibration generating unit 11 is provided at a substantially central position of the leaf spring 12X attached to the sound generating board 2 at a position outside the outermost diameter, so that the magnetic circuit unit 24 of the vibration generating unit 11 is provided. It is possible to generate vibration for the voice coil 26 under the condition that gravity does not substantially affect the annular magnet 21, the outer yoke 22, and the plate 23 that constitute the magnetic circuit portion 24.

  Accordingly, even with the configuration of FIG. 6, the vibration can be maintained without causing the vibration of the voice coil 26 and the bobbin 25 and hence the voice coil center portion 28 with respect to the magnetic circuit portion 24, so that the vibration transmission efficiency can be further improved. Can be increased.

(3-2) FIG. 7 shows still another embodiment. As shown in FIG. 7 with the same reference numerals assigned to corresponding parts to those in FIGS. 1 and 2, the leaf spring 12Y in FIG. The vertical plate portions 12AY1 and 12AY2 and the horizontal plate portions 12AY3 and 12AY4 having substantially the same length in the vertical direction and the horizontal direction centering on the generating portion 11 are extended in a cross shape.

  Thus, the leaf spring 12Y is attached to the mounting plate portions 12CY1, 12CY2, and 12CY3 at positions outside the outermost diameter of the vibration generating portion 11, that is, at positions separated from each other in the vertical and horizontal directions by substantially the same length around the vibration generating portion 11. 12CY4 is attached to the outer surface 2A of the sound generating board 2 by means of mounting screws 13Y1, 13Y2, 13Y3 and 13Y4.

  According to the configuration of FIG. 7, the annular magnet 21, the outer yoke 22 and the plate 23 and the voice coil center portion 28 constituting the magnetic circuit unit 24 are relatively vibrated with high accuracy in both the vertical direction and the horizontal direction. Therefore, vibration generated by the voice coil 26 can be transmitted to the sound generating board 2 more efficiently.

(3-3) In the above-described embodiment (FIG. 1), the present invention has been described with respect to the case where the board speaker 1 is configured by using the back plate of the casing of the liquid crystal television as the sound generation board 2. The portion where the speaker 1 is provided is not limited to the back plate, and may be a side plate. In this way, sound can be generated from the image display surface of the housing.

(3-4) In the above-described embodiment, the case where the present invention is applied to the case of a liquid crystal television is described. However, the application target is not limited to this, and a user such as a case of a personal computer listens to voice. It can be widely applied to equipment designed to take.

  Further, not only the board speaker 1 is combined with a device adapted to listen to sound, but an independent diaphragm that is separate from the housing of the device is used as the sound generating board 2. good.

(3-5) In the above-described embodiment, the case where the board speaker 1 is attached to the sound generating board 2 having a vertical surface has been described, but the sound generating board 2 is attached to the inclined surface portion or the horizontal surface portion. It may be attached.

  Also in this case, the leaf spring 12 of the board speaker 1 causes the magnetic circuit portion 24 to vibrate in a perpendicular direction without causing kinking with respect to the mounting surface of the sound generating board 2. By supporting 24, the vibration from the vibration generating unit 11 can be efficiently transmitted to the sound generating board 2.

(3-6) In the embodiment described above with reference to FIGS. 1 and 2, the case where the leaf spring 12 has the longitudinal plate portion 12 </ b> A having a size of 10 cm in length and 2 to 4 cm in width has been described. However, the vertical length of the vertical plate portion 12A is set so that the mounting plate portion 12C is attached to the sound generating board 2 at a position outside the outermost diameter portion of the vibration generating portion 11. It may be shortened or lengthened, and even in this case, as in the case described above, it is possible to obtain an effect of appropriately vibrating so as not to cause a rotation mode in the vibration direction of the magnetic circuit unit 24.

(3-7) In the above-described embodiment, the case where a plastic material is used as the leaf spring 12 has been described, but instead of this, a metal spring material such as phosphor bronze, duralumin, aluminum, or the like may be used. .

(3-8) In the above-described embodiment, the case where a plate material having a rectangular cross section is used as the plate spring 12 is described. Instead, a plurality of through holes penetrating the thickness of the plate material are provided. Anyway.

  In this way, the compliance of the leaf spring 12 can be further increased.

  The present invention can be used in the case where vibration in the audible frequency range is applied to the sound generating board.

  DESCRIPTION OF SYMBOLS 1 ... Board speaker, 1L, 1R ... Left and right channel board speaker, 2 ... Sound generating board, 2A ... Outer surface, 3 ... Vibration forming mechanism, 11 ... Vibration generating part, 12 ... Leaf spring, 12A, 12AX1 to 12AX2, 12AY1 to 12AY2 ... Vertical plate portion, 12B ... Support plate portion, 12C, 12CX1 to 12CX2, 12CY1 to 12CY4 ... Mounting plate portion, 12D ... Bent portion, 12AY3 to 12AY4 ...... Horizontal plate, 13, 13X1 to 13X2, 13Y1 to 13Y4 ... Mounting screw, 21 ... Ring ring magnet, 22 ... Outer yoke, 22B ... Cylinder yoke, 23 ... Plate, 24 ... Magnetic circuit , 25... Bobbin, 26... Voice coil, 28... Voice coil center, 31... Mounting screw, 32. ... support base, 38 ...... support frame, 38A ...... aggregate, 40, 42, 43 ...... connection terminal, 41 ...... printed wiring.

Claims (3)

In a board speaker having a vibration generating unit that transmits the vibration of the voice coil interlinked with the magnetic flux of the magnetic circuit unit to the surface of the sound generating board,
A leaf spring comprising one end attached to the surface of the sound generating board and the other end secured to the magnetic circuit;
The leaf spring is provided with the other end substantially parallel to the surface of the sound generating board so as to transmit the vibration of the magnetic circuit portion in a direction perpendicular to the surface of the sound generating board. Board speaker characterized by. A support base made of a ring-like viscoelastic body is provided at a position corresponding to the outermost diameter part of the magnetic circuit part on the surface of the sound generating board, and the magnetic circuit part is supported by the support base. The board speaker according to claim 1. The board speaker according to claim 1, wherein the board speaker is provided as a sound source of the image display device on a surface other than the image display surface of the housing of the image display device.

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