JP2007243851A - Planar speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar speaker adapted to the flattening of frequency characteristics and the enlarging and thinning of a display device without restricting a position attached with an actuator. <P>SOLUTION: The planar speaker comprises a diaphragm (10) with a great longitudinal length ratio, a casing (30) supporting the diaphragm (10) at the edge of an opening, and one or a plurality of actuators (21, 22, 23...) attached to the rear side of the diaphragm (10) to generate sounds of different pitch extents or different right and left channels. The planar speaker further includes reinforcement members (11, 12) which are attached on the rear side of the diaphragm (10) and extend in the lengthwise direction thereof. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flat speaker having a large aspect ratio used in combination with a display device such as a personal computer or a television.

  Conventionally, as a loudspeaker used in combination with a display device such as a personal computer or a TV, it is arranged using a long and narrow space formed on the left and right or upper and lower peripheral portions of the display screen, or to enhance the aesthetics of the design. In addition, there may be a need for a flat type having a large length ratio. The length ratio is typically 10 times or more. Such a loudspeaker having a large longitudinal ratio has advantages such as a lower manufacturing cost than a case where a large number of small speakers are arranged and an increase in the area of the diaphragm, resulting in better bass characteristics.

  As a typical structure of a flat speaker having a large longitudinal ratio, a diaphragm having a large longitudinal ratio is supported on the peripheral edge of the opening of the box, and a plurality of actuators are attached to the rear surface of the diaphragm (Patent Document 1, 2), and the like, in which a single actuator is attached to the back surface of the diaphragm (Patent Document 3).

Even in a flat speaker having a large aspect ratio, it is ideal that the diaphragm vibrates in the front-rear direction while maintaining a flat plate state, as in the other speakers. However, as the length of the diaphragm increases, bending vibration tends to occur along the longitudinal direction of the diaphragm. This bending vibration causes large peaks and valleys to appear in the frequency characteristics of the vibration as the natural vibration of the diaphragm, and the deviation from the ideal flat characteristic becomes significant. So-called flattening (stabilization) is required to prevent peaks and valleys from appearing in the frequency characteristics. In Patent Document 1, the frequency characteristics are flattened by adjusting the mounting positions of a plurality of actuators.
JP-A-63-155997 Japanese Patent Publication No. 8-4355 Japanese Patent Publication No. 3-25999

  In the structure for flattening the frequency characteristics as disclosed in Patent Document 1, there are restrictions on the mounting positions of a plurality of actuators, and the flattening effect is not always sufficient. In addition, with this type of flat speaker, there is a problem that the acoustic characteristics are easily influenced by the situation of the back surface of the display device as the display device to be combined is made thinner. Furthermore, there is also a problem that a larger vertical ratio is required with an increase in the size of such a display device.

  Accordingly, an object of the present invention is to provide a flat speaker capable of flattening frequency characteristics without restricting the mounting position of an actuator. Another object of the present invention is to provide a flat speaker that can sufficiently cope with the reduction in thickness and size of a display device.

  The flat speaker of the present invention that solves the above-mentioned problems of the prior art includes a diaphragm having a large aspect ratio, a box that supports the diaphragm at the peripheral portion of the opening, and 1 or 2 attached to the rear surface of the diaphragm. And a plurality of actuators. The planar speaker further includes a reinforcing member that is attached to the rear surface of the diaphragm and extends along the longitudinal direction thereof.

  In the flat speaker of the present invention, a reinforcing member that extends along the longitudinal direction of the diaphragm having a large aspect ratio is attached to the diaphragm. For this reason, the resonance Q value is lowered with an increase in the amount of vibration energy dissipated inside the reinforcing member, and the resonance vibration of the bending vibration with an increase in rigidity relative to the longitudinal deflection of the diaphragm as a whole. The plate is pushed up to a high frequency, and the frequency characteristics are flattened.

  In addition, by housing the actuator inside the box, there is also an effect that the influence of the back surface of the display device whose acoustic characteristics are reduced is less likely to be affected.

  According to one preferred embodiment of the present invention, two plate-like bodies in which the reinforcing member is spaced apart from each other in the longitudinal direction across the center line in the width direction of the diaphragm and extended in parallel, and these plates And a plate-like connecting portion that extends in parallel with each other along the width direction of the plate-like body and connects the plate-like bodies to each other, thereby suppressing an increase in the weight of the reinforcing member and bending vibration in the longitudinal direction of the diaphragm. The rigidity against is increased.

  According to another preferred embodiment of the present invention, the tip portion of the high-frequency dedicated actuator is attached to the back surface of the central portion in the width direction of the diaphragm and the rear end portion is connected to the connecting portion via the metal heat sink. Mounted on. Due to this actuator mounting structure, a large rigidity against bending vibration is added to the diaphragm, and the frequency characteristics are further flattened.

  According to another preferred embodiment of the present invention, by sharing the diaphragm in which the actuator for exclusive use of the middle / low sound is also attached to the diaphragm to which the actuator for exclusive use of high sound is attached, the entire speaker system is provided. The manufacturing cost has been reduced. For the middle / low-frequency dedicated actuator, the front end is attached to the back surface of the central portion in the width direction of the diaphragm, and the rear end is attached to the inner wall surface of the box, thereby reducing the weight of the diaphragm. The efficiency of excitation can be improved.

  According to another preferred embodiment of the present invention, by further including a port that also functions as a bass reflex that also functions as an air vent formed on the back surface of the box, the characteristics of the bass range can be improved.

  FIG. 1 is a diagram showing the configuration of a flat speaker according to an embodiment of the present invention. 1A is a partial plan view of this flat speaker, FIG. 1B is a cross-sectional view taken along the line bb ′ of FIG. 1A, and FIG. FIG. 4D is a cross-sectional view taken along the line dd ′ in FIG.

  The diaphragm 10 has a rectangular shape with a large length ratio, and is composed of a resin flat plate having a uniform thickness in the longitudinal direction and the width direction. The longitudinal ratio of the diaphragm 10 is assumed to be a large value range of 10 or more with the recent increase in the size of display devices. A peripheral portion of the diaphragm 10 is attached to an inner peripheral portion of an opening of the box body 30 that is integrally manufactured by resin injection molding or the like via an edge 13 made of cloth or rubber.

  On the back surface of the diaphragm 10, two thin plate-like reinforcing members 11 and 12 that are extended in the longitudinal direction while being opposed in parallel to each other across the center line in the width direction are attached. The reinforcing members 11 and 12 serve to increase the rigidity against bending of the diaphragm 10 in the longitudinal direction. When the weight of the diaphragm 10 as a whole increases with the addition of the reinforcing member, there arises a problem that the power necessary for exciting the diaphragm 10 increases and the excitation efficiency decreases. Considering this point, in order to reduce the weight as much as possible while maintaining the rigidity of the reinforcing members 11 and 12 at a constant value, a number of round holes having different diameters are formed in the longitudinal direction. The two reinforcing members are further connected to each other by connecting members formed at appropriate positions in the longitudinal direction, whereby the rigidity is further enhanced.

  On the rear surface of the diaphragm 10, low / mid range actuators 21 and 22 (not shown) and a high range actuator (tweeter) 23 are attached. Each actuator is a drive line wheel type actuator, and the tip surface of a cylindrical bobbin around which a voice coil is wound is bonded and fixed to the back surface of the diaphragm 10 with a disk-shaped sub-panel interposed. The low and middle sound range actuators 21 and 22 are attached to the back surface of the middle portion between both ends and the center portion of the diaphragm 10, and the tweeter 23 is attached to the back surface of the center portion of the diaphragm.

  The rear part that accommodates the magnetic circuit of the low / mid-range actuator 21 has an annular buffer 44 interposed on an annular tip surface of a cylindrical holding part 33 formed on the inner surface of the box 30. Is retained. On the other hand, the rear part that accommodates the magnetic circuit of the high-frequency actuator 23 is a metal rectangular holding plate 41 that also serves as a heat sink on the flat connecting parts 14 and 15 that connect the reinforcing members 11 and 12. And the rectangular buffer bodies 42 and 43 are held.

  Inside the box 30, ports 31 and 32 (not shown) that serve as air vents and bass reflexes and four thin cylindrical stoppers 35, 36, 37 and 38 ( (Not shown) is formed. Each stopper is for restricting the downward deflection of the diaphragm 10 in order to avoid the diaphragm 10 from being greatly bent and broken downward due to the contact of the operator or the user's hand.

  The flat speaker in FIG. 1 is installed in an elongated space formed in the left and right peripheral portions of a display device such as a personal computer or a television liquid crystal panel. A signal current for generating a right or left audio signal is supplied to the actuators 21, 22, and 23 through a signal line (not shown). When this signal current flows through the voice coil installed in the magnetic gap of the magnetic circuit of each actuator, a driving force in the front-rear direction corresponding to the polarity and strength of the signal current is generated in this voice coil. The wound bobbin vibrates back and forth. This back-and-forth movement of the bobbin is transmitted to the diaphragm 10, and the diaphragm 10 vibrates back and forth to generate sound.

  If the diaphragm 10 is an ideal rigid body that is sufficiently rigid and does not deform at all, an audio signal is faithfully reproduced based on vibrations in the front-rear direction of the diaphragm 10. Actually, since it is difficult to sufficiently increase the rigidity of the diaphragm 10, the deformation occurs. The deformation of the vibration plate 10 that is most likely to occur is a flexural vibration in the longitudinal direction that is caused by a vibration in the front-rear direction of a place that is separated from the vibration in the front-rear direction of the fixed portion of each actuator. The bending vibration in the longitudinal direction has a natural frequency (resonance frequency) determined from the rigidity of the diaphragm 10 and the distributed mass. When the inherent bending vibration of the diaphragm is combined with the ideal longitudinal vibration of the diaphragm 10, the reproduced audio signal is distorted. This also causes peaks and valleys to appear in the frequency characteristics, and impairs their flatness.

  In order to prevent this bending vibration, the rigidity of the diaphragm 10 may be sufficiently increased. The simplest is to increase the thickness of the diaphragm 10 uniformly. However, along with this, the weight of the diaphragm 10 also increases. As a result, there is a problem that a large excitation power is required and the excitation efficiency is lowered. Therefore, the planar speaker of FIG. 1 has a structure that increases the rigidity of the diaphragm 10 in the longitudinal direction while suppressing an increase in the weight of the entire diaphragm including the reinforcing members 11 and 12. That is, thin flat reinforcing members 11 and 12 having a maximum dimension in a direction orthogonal to the diaphragm 10 are attached to the back surface of the diaphragm. Further, as described above with respect to the mounting structure of the rear portion of the actuator 23 in the high sound range, the reinforcing members 11 and 12 are connected by the connecting portions 14 and 15 at appropriate positions in the longitudinal direction, whereby the rigidity of the diaphragm 10 is increased. Further enhanced.

  The addition of the reinforcing members 11 and 12 and the connecting portions 14 and 15 increases the amount of vibration energy dissipated inside the reinforcing member and the connecting portion. That is, inside the reinforcing member, vibration energy is converted into heat by friction inside the material and dissipated to the periphery. As a material suitable for this, a resin that generates a large internal friction compared to metal is excellent. As a result, the Q value of resonance of flexural vibration is reduced, and the acoustic characteristics are flattened. At the same time, since the rigidity is increased as compared with the weight of the diaphragm 10 as a whole including the reinforcing members 11 and 12, the resonance frequency of the flexural vibration is pushed up to a high range.

  Furthermore, at the location where the high frequency range actuator 23 is mounted, the conversion and dissipation of vibration energy generated in the metal rectangular holding plate 41, which also serves as a heat sink, and the shock absorbers 42, 43 are also flexed. This contributes to a decrease in the Q value. In other words, the Q value can be reduced and the frequency characteristics can be further flattened by the mounting structure itself of the high frequency range actuator 23 to the diaphragm 10.

  In the flat speaker shown in FIG. 1, a plurality of different types of actuators for low / mid range reproduction and high range reproduction are attached to one diaphragm. This is because the common diaphragm serves as both the reproduction and mixing of sounds having different properties such as the sound range. As a result, the manufacturing cost of the entire system can be greatly reduced as compared with a speaker having a configuration in which a diaphragm is provided for each type of sound to be reproduced.

  FIG. 2 is a diagram showing the configuration of a flat speaker according to another embodiment of the present invention. 2A is a partial plan view of the flat speaker of this embodiment, FIG. 2B is a cross-sectional view taken along the line bb ′ of FIG. 2A, and FIG. The figure and the figure (D) are dd 'sectional views of the figure (B). In FIG. 2, the constituent elements having the same reference numerals as those in FIG. 1 are the same constituent elements as those already described with reference to FIG.

  The flat speaker of this embodiment is different from the flat speaker shown in FIG. 1 in that two actuators 21 and 22 in the low / mid range are arranged with the center line in the longitudinal direction of the diaphragm 10 in between. This is that only one actuator 23 is attached to a position closer to the end of the diaphragm 10 than the center in the longitudinal direction.

  The attachment structure of the low and middle sound range actuators 21 and 22 to the diaphragm 10 and the bottom surface of the box 30 is the same as that shown in FIG. The mounting structure of the single high-frequency actuator 23 to the connecting portions 14 and 15 that connect the diaphragm 10 and the reinforcing members 11 and 12 is the same as that shown in FIG. Therefore, the redundant description of the specific mounting structure of each actuator is omitted.

  In the flat speaker of this embodiment, actuators 21 and 22 in the low / mid range are attached to substantially the center of the diaphragm 10, and a single high range actuator 23 is attached in the vicinity.

  The planar speaker of this embodiment is also arranged in each of the vertically long spaces formed on the left and right of the display screen of the display device, as in the embodiment of FIG. 22 and one high frequency range actuator 23 can be used to reproduce the left or right audio signal.

  FIG. 3 is a diagram showing the configuration of a flat speaker according to still another embodiment of the present invention. 3A is a partial plan view of the flat speaker of this embodiment, FIG. 3B is a cross-sectional view taken along the line bb ′ of FIG. 2A, and FIG. (D) is a dd ′ cross-sectional view of FIG. (B). In FIG. 3, the components given the same reference numerals as those in FIGS. 1 and 2 are the same as those already described with reference to FIGS. 1 and 2, and redundant description thereof will be omitted.

  The first difference between the flat speaker of the embodiment of FIG. 3 and the flat speaker shown in FIG. 2 is that two actuators 21 and 22 (not shown) in the low / mid range are arranged in the longitudinal direction of the diaphragm 10. The high-frequency range actuators 23 and 24 (not shown) are arranged near the center in the longitudinal direction of the diaphragm 10 adjacent to the left and right ends. 1 and 2 is the same as that of the diaphragm 10 of the low and middle sound range actuators 21 and 22 on the bottom surface of the box 30 and the vibration plate 10 and the reinforcing member 11 of the high frequency range actuators 23 and 24. , 12 are connected to the connecting portions 14, 15 in the same manner as in FIGS. Therefore, the redundant description of the specific mounting structure of each actuator is omitted.

  The flat speaker of this embodiment includes low and medium range actuators 21 and 22 (not shown) and high range actuators 23 and 24 (not shown) on the left and right sides of the diaphragm 10, respectively. ing. For this reason, the planar speaker of this embodiment is disposed in each of the horizontally long spaces formed at the top and bottom of the display screen of the display device, and the left audio signal is sent to the low / mid range actuator 21 and the high range actuator 23. Can be used so that the low- and mid-range actuator 22 (not shown) and the high-range actuator 24 (not shown) reproduce the left audio signal.

  That is, in the planar speaker of FIG. 3, a plurality of different types of actuators for reproducing sounds of different properties such as a sound range and left and right channel sounds are attached to one diaphragm. This means that the common diaphragm 10 serves for both reproduction and mixing of sounds having different properties such as a sound range and left and right channels. As a result, the manufacturing cost of the entire system can be greatly reduced compared to a speaker having a configuration in which a diaphragm is provided for each type of sound to be reproduced.

  2 is different from the flat speaker shown in FIG. 2 in that an actuator (woofer) 25 having an ultra-low range is formed at the center of the diaphragm 10 in the longitudinal direction, and a port 31 is used. , 32 is a point where the central portion is formed adjacent to the woofer 25 instead of the end of the box 30.

  Since the size of the woofer 25 is large, it is attached to the bottom surface outside the box body 30 for the purpose of preventing the box body 30 from being enlarged. For this reason, the front end portion of the cylindrical bobbin of the woofer 25 is extended inside the box 30 and the front end surface thereof is bonded and fixed to the back surface of the diaphragm 10 via the disk-shaped sub-panel. Sound is also reproduced directly from the cone of the woofer 25 and radiated into the box 30.

  Cylindrical ports 31 and 32 that serve as air vents and bass reflexes are formed on the left and right sides of the woofer 25. When the bass component reproduced by the woofer 25 and radiated into the box 30 behind the diaphragm 10 passes through the ports 31 and 32 and wraps around the front of the diaphragm 10, it radiates forward of the diaphragm 10. The ports 31 and 32 are arranged so that the sound is directly reproduced from the super bass component and the line of the woofer 25 and is synthesized with a predetermined phase relationship with the line segment that wraps around the front of the box 30. The length has been adjusted.

  FIG. 4 shows frequency characteristics obtained by comparing measured data of the flat speaker of the present invention. A curve a is actually measured data obtained for the structure shown in FIG. Curve b in the figure is actual measurement data obtained for a structure in which the reinforcing member and the connecting portion are removed from the structure shown in FIG. 1 and a high-frequency range actuator is attached to the back surface of the flat diaphragm. . The flatness of the frequency characteristic is improved by attaching the reinforcing member and the connecting portion.

  FIG. 5 shows frequency characteristics obtained by comparing measured data of the flat speaker of the present invention. A curve a in the figure is actual measurement data obtained for the structure shown in FIG. Curve b in the figure functions as a stabilizer for dumping resonance with respect to the diaphragm by the actuator 23 in the high sound range from the structure shown in FIG.

  FIG. 6 shows measured data (curve a) obtained when the length of the left and right ports 31 and 32 is adjusted to the bass reflex state in the structure of the embodiment of FIG. It is actual measurement data (curve b) obtained when the length is not adjusted and the bass reflex state is not set. By adjusting the bass reflex state according to the lengths of the ports 31 and 32, improvement in the characteristics of the low frequency range can be seen.

  As described above, the configuration in which a plurality of different types of actuators covering different sound ranges, left or right channels, and the like are attached to one diaphragm is illustrated. However, the present invention can also be applied to a case where the plurality of actuators are the same actuator for reproducing the sound of the same sound range and the left and right channels.

  In addition, it is possible to adopt a configuration in which the resonance Q of flexural vibration is further reduced by attaching a film such as rubber excellent in the effect of dissipation of vibration energy to the reinforcing member.

The top view which shows the structure of the flat speaker of one Example of this invention (A), bb 'sectional drawing (B) of a figure (A) Bottom view (C), FIG. ) Is a cross-sectional view (D) of dd ′.

The fragmentary top view (A) which shows the structure of the planar speaker of the other Example of this invention, bb 'sectional drawing (B) of FIG. (A), the bottom view (C) which cuts and shows one part, FIG. It is dd 'sectional drawing (D) of (B).

The fragmentary top view (A) which shows the structure of the planar speaker of the further another Example of this invention, bb 'sectional drawing (B) of FIG. It is dd 'sectional drawing (D) of a figure (B).

It is actual measurement data which shows the characteristic of the flat speaker of FIG. 1 of this invention compared with the flat speaker of another structure.

It is actual measurement data which shows the characteristic of the flat speaker of FIG. 1 of this invention compared with the flat speaker of another structure.

It is actual measurement data which shows the characteristic of the flat speaker of FIG. 1 of this invention compared with the flat speaker of another structure.

Explanation of symbols

10 Diaphragm
11,12 Reinforcement member
13 Edge
14,15 Connecting part
21-23 Drive line wheel type actuator
30 box
31 Port for both air vent and bass reflex
33 to 35 Holding section for holding low / mid range actuator
35-37 Cylindrical stopper
41 Holding plate that also serves as a heat sink
42-44 buffer

Claims (5)

In a flat speaker comprising a diaphragm having a large length ratio, a box that supports the diaphragm at the peripheral edge portion of the opening, and one or more actuators attached to the back surface of the diaphragm,
A flat speaker, further comprising a reinforcing member attached to the back surface of the diaphragm and extending along a longitudinal direction thereof. In claim 1,
The reinforcing member is
Two plate-like bodies extending in parallel to be spaced apart from each other in the longitudinal direction across the center line in the width direction of the diaphragm;
A flat speaker comprising: a plate-like connecting portion that extends parallel to each other along the width direction of the plate-like bodies and connects the plate-like bodies. In claim 2,
One of the one or more actuators has a front end portion attached to the back surface of the center portion in the width direction of the diaphragm and a rear end portion attached to the connecting portion via a metal heat sink. A flat speaker characterized by a high-tone dedicated actuator. In either claim 2 or 3,
One of the one or more actuators is an actuator for middle / low sounds, the front end of which is attached to the back surface of the central portion in the width direction of the diaphragm and the rear end is attached to the inner wall surface of the box. There is a flat speaker. In any one of Claims 1 thru | or 4,
A flat speaker further comprising a port formed on the back surface of the box and serving as an air vent.

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