JPS6127275Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a piezoelectric speaker whose drive source is a piezoelectric diaphragm made by bonding a piezoelectric material to a metal plate.

Piezoelectric speakers are being put into practical use because they have fewer parts, are cost-effective, and have no magnetic influence compared to speakers using magnetic circuits as a driving source.

An example of this type of piezoelectric speaker is shown in FIG.
In the figure, 1 is a disk-shaped piezoelectric diaphragm made by laminating a piezoelectric material on one or both sides of a metal plate and further forming electrodes on this piezoelectric material. Bending motion is achieved by applying acoustic signals to the plate and electrodes. 2 is a bottomed frame; 3 is a disc-shaped holding member made of a flexible material disposed on the inner surface of the bottom of the bottomed frame 2; on this holding member 3, the piezoelectric diaphragm 1 is adhered and held; There is. Reference numeral 4 denotes a conical paper cone, the top of which is connected to the center of the piezoelectric diaphragm 1, and the periphery of the cone to the open side of the bottomed frame 2.

A piezoelectric speaker having such a configuration uses a holding member 3 made of a flexible material to place the piezoelectric diaphragm 1 in a frame in a vibrating state. If the contact area with the member 3 is large, the vibration load of the piezoelectric diaphragm 1 will increase, and the driving force to the paper cone 4 will be attenuated, resulting in a decrease in the sound pressure of the reproduced sound. On the other hand, if the above-mentioned holding member 3 is provided with a through hole or the like to reduce the contact area with the piezoelectric diaphragm 1 in order to increase the sound pressure of the reproduced sound, the adhesion may come off due to the vibration of the piezoelectric diaphragm 1. This may lead to an accident in which the piezoelectric diaphragm 1 and the paper cone 4 fall off in a free edge type speaker in which the periphery of the paper cone is not connected to the frame.

The present invention was made with the aim of improving such disadvantages, and provides a piezoelectric speaker equipped with a holding member that has a high ability to hold the piezoelectric diaphragm even when the contact area with the piezoelectric diaphragm is reduced. This is what we provide.

FIG. 2 shows a sectional view of an embodiment of the piezoelectric speaker of the present invention, and FIGS. 3a, b, and c show perspective views of its main parts. In these figures, 5 is a disk-shaped piezoelectric diaphragm made by laminating a piezoelectric material 6 on one side of a thin metal plate 7 and further forming an electrode (not shown) on this piezoelectric material 6. A cut-and-raised protrusion 8 is provided at the center of the thin metal plate 7. 9
is an annular holding member made of urethane foam, which is a flexible material, and has an inner diameter approximately equal to the outer diameter of the piezoelectric diaphragm, as shown in FIG. 6 tongues protruding at intervals 1
0, 10... As shown in FIG. 3b, this holding member 9 holds the peripheral portion of the piezoelectric diaphragm 5 fitted into its inner periphery by means of six tongue pieces 10, 10, which are alternately distributed on both the front and back surfaces. This piezoelectric diaphragm 5 is held flexibly by adhesive clamping. Note that adhesive is applied to this bonding location. Reference numeral 11 denotes a frame, and a holding member 9 that holds the piezoelectric diaphragm 5 is attached so that the cut-and-raised protrusion 8 of the piezoelectric diaphragm 5 is located on the upper surface. As shown in FIG. 3c, this frame 11 consists of three cut-and-raised pieces 12, 12, 12 formed at equal intervals around a circular base plate, and two attachment pieces extending from the periphery of this circular base plate. These cut and raise pieces 12,
12, 12 elastically engages the periphery of the holding member 10. Reference numeral 14 denotes a conical paper cone, the top of which is adhesively bonded to a cut-and-raised protrusion 8 located at the center of the upper surface of the piezoelectric diaphragm 5 . 15
is a tight board, and the two mounting pieces 13 of the frame 11 are attached so that the cone paper 14 fits into the through hole 16 formed in the tight board 15.
13 is fixed with rivets 17, 17.

A piezoelectric speaker with such a configuration has a piezoelectric diaphragm 5.
The periphery of the six tongue pieces 10, 10 of the holding member 9...
Therefore, even if a free edge type structure in which the periphery of the cone paper 14 is not connected to a frame or the like is adopted, the piezoelectric Vibration plate 5
is prevented from falling off. In addition, when adopting a fixed edge type structure in which the periphery of the cone paper 14 is connected to a frame or the like, it is not always necessary to attach the tongues 10, 10... of the holding member 9 to the periphery of the piezoelectric diaphragm 5. No need to apply.

In FIG. 4, the frequency characteristic curve of the piezoelectric speaker of the present invention is shown by a solid line, and that of a conventional piezoelectric speaker is shown by a broken line. The frequency characteristic curve in the figure is the actual measured value for a speaker with a piezoelectric diaphragm with an outer diameter of 21 mm and a paper cone with a diameter of 35 mm, but the sound pressure of the piezoelectric speaker of this invention is higher than that of the conventional one. I understand things very well.

5 and 6 respectively show other embodiments of the piezoelectric speaker of the present invention, and in the case of FIG.
A vibration unit A consisting of a piezoelectric diaphragm 5 held by a holding member 9 and a paper cone 14 coupled thereto is attached to a printed circuit board 18 of an audio device such as a radio. are attached using adhesive. In the case of FIG. 6, a composite speaker is constructed by attaching the vibration unit A to a large bass speaker B, and a mounting base 21 is provided on the center pole 20 of the magnetic circuit 19 of the large speaker B. The vibration unit A is adhesively mounted on the mounting base 21 in the same manner as in FIG.

As is clear from the above description, the piezoelectric speaker of the present invention uses an annular flexible material holding member having a plurality of tongues on the inner periphery, and a disk-shaped piezoelectric speaker bonded to a cone-shaped paper cone. Since the plurality of tongues of the holding member are sandwiched around the periphery of the diaphragm so as to be distributed between the front and back surfaces, the contact area between the piezoelectric diaphragm and the holding member is reduced, and the sound pressure of the reproduced sound is increased. Also, it is possible to prevent the bond between the piezoelectric diaphragm and the holding member from coming off, thereby avoiding an accident in which the piezoelectric diaphragm and the paper cone fall off. Therefore, a highly reliable piezoelectric speaker with improved efficiency can be obtained.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional piezoelectric speaker, Figure 2 is a cross-sectional view of a conventional piezoelectric speaker.
The figure is a sectional view of an embodiment of the piezoelectric speaker of the present invention, Figures 3a, b, and c are perspective views of the main parts of the piezoelectric speaker of the present invention shown in Figure 2, and Figure 4 is the frequency characteristic. 5 and 6 respectively show a side view and a sectional view of another embodiment of the piezoelectric speaker of the present invention. 1, 5... Piezoelectric diaphragm, 2, 11... Frame, 3, 9... Holding member, 4, 14... Cone paper, 10... Tongue piece.

Claims (1)

[Claims for Utility Model Registration] 1. A disk-shaped piezoelectric diaphragm made by bonding a piezoelectric material to a thin metal plate, and a conical shape whose top is joined to a raised protrusion provided in the center of the thin metal plate. In a piezoelectric speaker comprising a cone paper and a holding member made of a flexible material for flexibly holding the piezoelectric diaphragm, the holding member has an inner diameter approximately equal to an outer diameter of the piezoelectric diaphragm. The holding member has an annular shape, and has a plurality of tongues on the inner periphery of the annular shape, and the plurality of tongues of the holding member grip the peripheral portion of the piezoelectric diaphragm so that they can be distributed between the front and back surfaces. Features a piezoelectric speaker. 2. The piezoelectric speaker according to claim 1, wherein the piezoelectric speaker is of a free edge type. 3. The piezoelectric speaker according to claim 2, wherein the piezoelectric speaker is adhesively mounted on a mounting base provided on a center pole of a large speaker to form a composite speaker. .