JPH04157899A - Panel loudspeaker - Google Patents

Abstract

PURPOSE:To thin the londspeaker and to install it adjacently to the wall surface without deteriorating an acoustic effect by providing a piezoelectric type acoustic driver formed by joining a piezoelectric element to a metallic plate, on an acoustic diaphragm consisting of a foaming body on which many through- holes are formed in the thickness direction. CONSTITUTION:The panel londspeaker A is formed by providing a piezoelectric type acoustic driver 13 on an acoustic diaphragm 1, and sticking two pieces of foam plates 11a, 11b consisting of modified polystyrene foam provided with many through-holes 2 in its thickness direction. The piezoelectric acoustic driver 13 is formed as a bimorph by joining a piezoelectric element 14 formed by providing an electrode film on both faces of a piezoelectric ceramic plate to both faces of a thin and circular metallic plate 15. In such a way, even when the panel loadspeaker A is installed adjacently to the wall surface, it does not occur that the reverse side of the acoustic diaphragm is filled with a sound and a distortion of the sound is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a panel speaker that is lightweight, thin, and used by being attached to the wall of a room.

[Prior Art] Conventional panel speakers include, for example, a panel speaker in which a piezoelectric acoustic driver is embedded in an acoustic diaphragm made of foamed resin, and a panel speaker in which a thin dynamic speaker is attached to a panel. There is a formed panel speaker. As shown in FIG. 6, these panel speakers 21 are fitted into, for example, a frame (not shown) and hung on a wall 22 in a room or a hallway.

[Problems to be Solved by the Invention] However, as shown in FIG. speaker 21
Since there is not a sufficient air layer between the panel speaker 21 (acoustic diaphragm) and the wall surface 22, sound is trapped between the panel speaker 21 (sound 9@moving plate) and the wall surface 22, and especially in the low frequency range, the sound is trapped. There is a problem in that no waves are generated and the sound is distorted, reducing the acoustic effect.

In order to solve this problem, for example, the seventh
As shown in the figure, the panel speaker 21 is hung diagonally on the wall surface 22 so that an appropriate air layer exists between the panel speaker 21 and the wall surface 22.

However, in this case, although the panel speaker 21 is used with emphasis on being thin, the panel speaker 21 is tilted and hung on the wall 22, so that the upper part of the panel speaker 21 protrudes from the wall 22. There is a serious problem that the purpose of using a thin panel speaker is lost, such as deteriorating the comfort of the room in which the panel speaker 21 is installed.

The present invention solves the above-mentioned problems, and aims to provide a panel speaker that is thin and can be installed close to a wall without reducing acoustic effects.

[Means for Solving the Problems] In order to solve the above problems, a panel speaker of the present invention includes: an acoustic diaphragm made of a foam plate in which a large number of through holes are formed in the thickness direction; It is characterized by comprising a piezoelectric type acoustic driver arranged on a plate and formed by bonding a piezoelectric element to a metal plate.

[Operation] The acoustic diaphragm in which a large number of through holes are formed in the thickness direction has excellent characteristics of being lightweight and having high rigidity, and improves the acoustic effect. Furthermore, when a panel speaker is installed close to a wall along the wall, the sound emitted toward the wall side (back side) of the panel speaker may be different from the sound emitted from the many through-holes in the thickness direction provided on the acoustic diaphragm. The sound emitted from the front side of the panel speaker through the hole and the sound scattered to the back side of the acoustic diaphragm are eliminated, reducing sound distortion.

Therefore, it is possible to place the panel speaker close to the wall surface without sacrificing the acoustic effect.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing the structure of a panel speaker according to an embodiment of the present invention. The panel speaker A is formed by disposing a piezoelectric acoustic driver 13 on the acoustic diaphragm 1. As shown in FIG. 1, this acoustic diaphragm 1 is made up of two foam plates 11a made of modified polystyrene foam with a large number of through holes 2 in the thickness direction.

−3= It is formed by bonding flbs together.

The through holes 2 are not formed in the mutually opposing predetermined portions (acoustic driver housing portions) 3 of the foam plates ILa and 11b provided with the through holes 2, and the acoustic driver housing portions 3 are not formed with the through holes 2.
A recess 12 is formed at positions facing each other, and a small protrusion 12a is formed within the recess 12. These mutually opposing recesses 12 form a space 18 (FIG. 3) in which the piezoelectric acoustic driver 13 is housed when the foam plates 11a and llb are bonded together.

As shown in the top and front views of FIGS. 4 and 5, the piezoelectric acoustic driver 13 has a piezoelectric element 14 formed by a thin circular piezoelectric element 14 provided with electric films (not shown) on both sides of a piezoelectric ceramic plate. It is formed by joining both sides of the metal plate 15 to form a bimorph structure, and the piezoelectric element 14 and the metal plate 1
5 is connected to a lead wire 16 (FIG. 5). This piezoelectric acoustic driver 13 is placed horizontally in the recess 12 of the foam board 11a, and the center of the piezoelectric element 14 is connected to the small protrusion 12a.
is glued to the top surface of the In addition, when the two foam plates 11a and llb are bonded together as shown in FIG.
2a and the center portion of the upper surface of the piezoelectric element 14 are bonded together.

That is, the piezoelectric acoustic driver 13 has small protrusions 12a, 12a on the foam plates 11a, 11b at the center of its upper and lower surfaces.
It is supported from above and below (centerly supported) by the recesses 12 and 12, and is housed in a space 18 formed by opposing recesses 12 and 12 in a manner suitable for vibration (FIG. 3). Further, the lead wires 16 connected to each piezoelectric type acoustic driver 13 are combined into two and drawn out from the end of the sound g diaphragm 1 as a lead wire 16a (FIG. 2).

In the panel speaker A formed as described above,
By connecting the lead wire 16a to the output terminal of an audio device (not shown) such as a stereo device and applying a predetermined voltage, the piezoelectric acoustic driver 13 vibrates in a 1l1111 manner, and the vibrations cause the acoustic diaphragm to vibrate. Sound propagates to 1 #diaphragm 1
vibrates as a whole to generate sound. Even when this panel speaker A is installed almost in close contact with a wall surface, the sound emitted to the wall side (back side) of the acoustic diaphragm 1 (acoustic oscillation -6 = vibration plate 1) is Sound is generated from the front surface of the panel speaker A through a large number of through holes 2 in the thickness direction. therefore,
Even when the panel speaker A is installed close to the wall surface (in close contact), the sound will not be trapped behind the acoustic diaphragm 1, the distortion of the sound will be reduced, and excellent acoustic effects can be obtained. can.

In the panel speaker A of the present invention, there is no particular restriction on the shape of the through-hole 2, and while maintaining a good acoustic effect, sound that is muffled on the back side of the acoustic diaphragm 1 can be removed from the through-hole 2 through the acoustic diaphragm 1. From the perspective of letting the air out to the front side, for example, through hole 2
If the shape is almost cylindrical, its diameter is 0.5 mm to 3 mm.
．． Preferably, it is in the range of 0 degrees.

In addition, the spacing between the through holes 2 should be small as long as it can provide the necessary rigidity to the acoustic diaphragm 1 and maintain a good acoustic effect.
It is preferable that the walls of a and 11b are thin.

Furthermore, the through hole 2 may be formed by molding the foam plates 11a and llb, and the piezoelectric acoustic driver 1
3 may be formed on the acoustic diaphragm 1 by press processing or other methods. In other words, the method and timing of forming the through holes 2 are not particularly limited, and may be formed depending on the ease of the manufacturing process or the formation time. An appropriate selection can be made in consideration of economic efficiency and the like.

In the above embodiment, the case where the shape of the acoustic diaphragm 1 is rectangular has been described, but the shape of the acoustic diaphragm 1 is not limited to a rectangle, and can be configured in various shapes such as a polygon and a circle. .

Further, in the above embodiment, a case was explained in which modified polystyrene foam was used as the constituent material of the acoustic diaphragm 1 (foam plates 11a, 1lb), but the constituent material of the sound I# diaphragm 1 is limited to this. It is not a material that contains bubbles, has a certain heat resistance (at least heat resistance at room temperature), and has an apparent density of 0.01 to
Materials within the range of 0.2 g/cn', such as modified styrene-polypropylene copolymer foam, polypropylene foam, polyethylene foam, polyurethane foam, and other materials can be used.

Further, in this invention, the structure for providing the piezoelectric acoustic driver 13 on the acoustic diaphragm 1 is the structure of the above embodiment (
(Stored in the acoustic driver storage section 3 by sandwiching the two foam plates 11a and lfb); for example,
- A recess is provided in the acoustic driver housing portion of the foam board, a piezoelectric acoustic driver is stored in the recess, and the piezoelectric acoustic driver is sealed with a sealing lid. Various structures can be adopted, such as forming a diaphragm (panel speaker).

Furthermore, in the above embodiment, the piezoelectric acoustic driver 1
3, a case has been described in which a piezoelectric acoustic driver with a bimorph structure in which the piezoelectric elements 14 are bonded to both sides of the metal plate 15 is used. For example, a piezoelectric acoustic driver (not shown) in which one piezoelectric element is bonded to one surface of a metal plate may be used.

Further, in the above embodiment, the piezoelectric acoustic driver 13
Although an example has been described in which the center is supported centrally by the small protrusions 12a, 12a from both the upper and lower surfaces (Fig. 5), it may be configured so that it is supported only from one side (for example, the bottom surface) (by the small protrusions 12a). .

Furthermore, as for the method of supporting the piezoelectric acoustic driver 13, is center support preferable?It is not necessarily limited to center support, and there are cases in which it is possible to obtain the necessary vibrations even if parts other than the center are supported. .

The total number of piezoelectric acoustic drivers 13 to be provided on the acoustic diaphragm 1 is preferably two or more from the viewpoint of sufficiently vibrating the entire acoustic diaphragm 1. Furthermore, there is no particular upper limit to the number, or it is desirable that the number be in the range of 2 to 16 in consideration of acoustic effects, economic efficiency, etc.

Further, the piezoelectric acoustic driver 13 has a thickness of approximately 0.
．． 2IIn, diameter = approx. 60-8011m, weight = approx. 8g
It is thin and lightweight, and the acoustic diaphragm 1 that accommodates it can be formed thin, and the acoustic diaphragm 1 is formed with many through holes 2, and is lightweight, so the panel speaker as a whole It is possible to realize thinner and lighter weight.

Furthermore, since the piezoelectric acoustic driver 13 has excellent frequency characteristics in the mid-to-high frequency range, by combining the panel speaker of the present invention with a normal dynamic speaker that has excellent frequency characteristics in the bass range, it is possible to achieve excellent frequency characteristics over the entire frequency range. It is possible to realize a sound effect that is unique to the user. Furthermore, some piezoelectric acoustic drivers have excellent frequency characteristics in the low frequency range, and when these are used, sufficient acoustic effects can be achieved with only the piezoelectric acoustic driver.

[Effects of the Invention] The panel speaker of the present invention has a piezoelectric acoustic driver disposed on an acoustic diaphragm formed by forming a large number of through holes in the thickness direction of a foam board, so that the acoustic diaphragm is lightweight. It has the excellent characteristics of being large and rigid, which improves the acoustic effect and reduces the amount of sound emitted toward the wall side (back side) of the panel speaker even when the panel speaker is installed almost closely against the wall. , the sound radiates from the front of the panel speaker through the numerous through-holes in the thickness direction provided in the acoustic diaphragm, and the muffled sound on the back side of the diaphragm is suppressed.
Sound distortion is reduced. Therefore, it is possible to arrange the panel speaker in close contact with the wall surface without deteriorating the acoustic effect, and the thin feature of the panel speaker can be fully utilized.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing the structure of a panel speaker according to an embodiment of the present invention, Fig. 2 is a perspective view showing the panel speaker after assembly, and Fig. 3 is a cross section showing the support structure of a piezoelectric acoustic driver. 4 and 5 are plan and front views showing a piezoelectric acoustic driver used in the panel speaker of the present invention, and FIGS. 6 and 7 show a conventional panel speaker hung on a wall. FIG. A...Panel speaker 1...Acoustic diaphragm 2...Through hole 13...Piezoelectric acoustic driver 14...Piezoelectric element 15. ...Metal plate patent applicant Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] (1) An acoustic diaphragm made of a foam plate with a large number of through holes formed in the thickness direction, and a piezoelectric acoustic driver formed by bonding a piezoelectric element to a metal plate, which is disposed on the acoustic diaphragm. A panel speaker characterized by: