JP5919499B2 - Sound generator - Google Patents

Description

  The present invention relates to a sound source device.

  Conventionally, a sound source device including a piezoelectric diaphragm in which a piezoelectric element is fixed to a diaphragm made of metal has been provided (see, for example, Patent Document 1). This type of sound source device is used as a sound source of an alarm sound, for example, in an alarm device that detects a human body and generates an alarm sound. Such a sound source device is also called a piezoelectric buzzer or a piezoelectric speaker.

  In order to obtain a loud sound, a cone diaphragm may be connected to one surface of the piezoelectric diaphragm. In general, the cone diaphragm is a thin plate made of synthetic resin or metal, and has a shape in which the center portion bulges to one side in the thickness direction, with the convex side facing the piezoelectric diaphragm, Is connected to the piezoelectric diaphragm at the central portion of each.

Japanese Utility Model Publication No. 1-79100

  Here, consider a case where a printed wiring board electrically connected to the piezoelectric diaphragm via an electric wire is housed in a common case with the piezoelectric diaphragm and the cone diaphragm. In the above case, if the printed wiring board is arranged so as not to overlap the cone diaphragm as viewed from the thickness direction, the size of the case in the direction along the surface of the printed wiring board becomes large.

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide a sound source device that can be reduced in size.

  The sound source device of the present invention includes a piezoelectric diaphragm in which a piezoelectric element is fixed to at least one surface of a diaphragm made of metal, a cone diaphragm connected to the piezoelectric diaphragm, and the piezoelectric element via a plurality of electric wires. A printed wiring board electrically connected to the diaphragm, a cover having a sound hole closed by the cone diaphragm, and an outer peripheral end of the cone diaphragm sandwiched between the cover and the cover A back cover to be coupled, and a base that constitutes a case that is coupled to the cover and houses the piezoelectric diaphragm, the printed wiring board, and the back cover, as viewed from the thickness direction of the printed wiring board, A part of the printed wiring board, a part of the cone diaphragm, and a part of the back cover overlap each other, and the electric wire is sandwiched between the back cover and the base. Wherein the electric wire holding projection for determining is provided.

  In the above-described sound source device, it is preferable that the connection portion of the electric wire is disposed at an end portion on a side close to the piezoelectric diaphragm in the printed wiring board.

  According to the present invention, as viewed from the thickness direction of the printed wiring board, a part of the printed wiring board and a part of the cone diaphragm and the back cover are overlapped with each other. Thus, it is possible to reduce the size in the direction parallel to the surface of the printed wiring board. In addition, since the positioning of the electric wire is achieved by the electric wire holding projection provided on the back cover, it is possible to reduce the size compared to the case where a component that sandwiches the electric wire between the back cover and the base is separately provided. It is.

It is a rear view which shows the state by which the base was removed in embodiment of this invention. (A)-(c) shows each same as the above, (a) is a front view, (b) is a right view, (c) is sectional drawing in the AA cross section of (a).

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  In this embodiment, as shown in FIGS. 1 and 2, a piezoelectric diaphragm 11, a cone diaphragm 12 connected to the piezoelectric diaphragm 11, and three piezoelectric wires are electrically connected to the piezoelectric diaphragm. And a printed wiring board 3 connected to the case 4 and a case 4 for storing the above-described parts.

  Hereinafter, the vertical and horizontal directions are based on FIG. 2A, and the horizontal direction in FIG. 2B (that is, the right-left direction in FIG. 2C) is referred to as the front-rear direction.

  The piezoelectric diaphragm 11 is a so-called bimorph type in which the piezoelectric elements 111 are fixed to both the front and back surfaces of the metal diaphragm 110 with the thickness direction oriented in the front-rear direction. The diaphragm 110 and each piezoelectric element 111 have a disk shape having a center on the same axis, and the diameter of the diaphragm 110 is larger than the diameter of each piezoelectric element 111. One electric wire 2 is connected to the diaphragm 110 and each piezoelectric element 111 by soldering, for example.

  The cone diaphragm 12 is composed of a thin plate having a truncated cone shape as a whole with a disc-shaped central portion whose thickness direction is directed in the front-rear direction, and the rear surface of the central portion is a front piezoelectric element. 111 is fixed to the central portion. The cone diaphragm 12 is made of, for example, a synthetic resin or metal film.

  The case 4 includes a cover 41 in which a housing recess 410 that houses the piezoelectric diaphragm 11, the cone diaphragm 12, the electric wires 2, and the printed wiring board 3 is opened, and a housing recess that is coupled to the rear side of the cover 41. And a base 42 for closing 410. As means for coupling the cover 41 and the base 42 to each other, for example, well-known means such as welding, adhesion, and fitting can be appropriately employed.

  Furthermore, the present embodiment includes a back cover 5 that is coupled to the cover 41 in such a manner that the outer peripheral end of the cone diaphragm 12 is sandwiched from the front-rear direction with an annular step 411 provided in the storage recess 410. . As means for coupling the back cover 5 and the cover 41 to each other, for example, well-known means such as welding and adhesion can be appropriately employed. On the front side of the cone diaphragm 12, four arc-shaped sound holes 40 in which one circular ring is divided into four are provided on the bottom surface of the storage recess 410. The cone diaphragm 12 is fixed to the back cover 5 and is in close contact with the step 411 of the cover 41 in an annular shape surrounding the four sound holes 40 over the entire circumference when viewed from the rear. That is, the sound hole 40 is closed by the cone diaphragm 12.

  The printed wiring board 3 is a rectangular flat plate, and is disposed below the piezoelectric diaphragm 11 with the mounting surface facing forward and the longitudinal direction facing left and right. Here, the upper end portion of the printed wiring board 3 is located on the rear side of the cone diaphragm 12 and the lower end portion of the back cover 5 (left side in FIG. 2C). In other words, when viewed from the front-rear direction, which is the thickness direction of the printed wiring board 3, a part of the printed wiring board 3 and a part of the cone diaphragm 12 and the back cover 5 overlap each other. The base 42 is provided with support convex portions 421 that support the vicinity of the four corners of the printed wiring board 3 between the back cover 5 and the rear surface of the cover 41.

  Furthermore, the other end of each electric wire 2 having one end connected to the piezoelectric diaphragm 11 is connected to the non-mounting surface (rear surface) of the printed wiring board 3 by soldering. Here, the connection place of the electric wire 2 in the printed wiring board 3 is left and right along the upper edge, which is the edge facing the piezoelectric diaphragm 11, at the upper end, which is the end near the piezoelectric diaphragm 11. They are arranged side by side. Thereby, compared with the case where each electric wire 2 is connected to the center part of the printed wiring board 3, for example, each electric wire 2 can be shortened, respectively.

  A cylindrical receptacle 43 is provided on the right surface of the cover 41 so as to protrude rightward. The other end portions of a plurality of (six in the figure) contacts 6 each having one end portion inserted and mounted on the printed wiring board 3 are exposed inside the receptacle portion 43. The contacts 6 are held on the cover 41 side by side, for example, by insert molding. A plug (not shown) having a contact that is in one-to-one contact with the contact 6 is detachably connected to the receptacle 43 by, for example, a structure in which fitting and uneven engagement are combined. The through holes 31 into which the contacts 6 are inserted in the printed wiring board 3 are provided side by side on the printed wiring board 3 as shown in FIG. The printed wiring board 3 is mounted with a circuit for driving the piezoelectric diaphragm 11 in accordance with an electric signal input through the plug and the contact 6.

  Here, the fixing of the present embodiment is performed using the mounting screw 7 with the head 71 facing forward on the rear side of the base 42. Specifically, the base 42 is provided with a screw coupling portion 44 that holds the head 71 of the mounting screw 7 from the front and rear. The screw coupling portion 44 is provided with a screw insertion portion 440 that is formed by a notch opened upward and in the front-rear direction and into which the leg portion 72 of the mounting screw 7 is inserted.

  In addition, on the rear surface of the back cover 5, an electric wire holding convex portion 51 that projects one electric wire 2 between the front surface of the base 42 and protrudes rearward. Each electric wire 2 is positioned by being fitted, for example, into a concave portion provided at the front end portion (rear end portion) of the electric wire holding convex portion 51.

  According to the above configuration, when viewed from the front-rear direction, which is the thickness direction of the printed wiring board 3, a part of the printed wiring board 3 and a part of the cone diaphragm 12 and the back cover 5 overlap each other. Compared with the case where each part does not overlap each other, it is possible to reduce the size in the direction parallel to the surface of the printed wiring board 3 (the vertical and horizontal directions in FIG. 1). Further, since the positioning of the electric wire 2 is achieved by the electric wire holding convex portion 51 provided on the back cover 5, the size of the component that sandwiches the electric wire 2 between the back cover 5 and the base cover 42 is reduced as compared with the case where it is provided separately. (Thinning) is possible.

  Moreover, since the electric wire holding convex part 51 pinches the electric wire 2 between the base 42, compared with the case where the electric wire holding convex part 51 is made into the clip shape which pinches | interposes the electric wire 2 from the front-back direction, for example, the assembly operation is relatively mechanized. It will be easier.

  The piezoelectric diaphragm 11 may be a so-called monomorph type in which the piezoelectric element 111 is fixed to only one surface of the diaphragm 110 instead of the bimorph type as described above. In that case, the number of electric wires 2 connected to the piezoelectric diaphragm 11 is two, one for each of the diaphragm 110 and the piezoelectric element 111.

2 Electric wire 3 Printed wiring board 4 Case 5 Back cover 11 Piezoelectric vibration plate 12 Cone vibration plate 40 Sound hole 41 Cover 42 Base 51 Electric wire holding convex portion 110 Vibration plate 111 Piezoelectric element

Claims (2)

A piezoelectric diaphragm in which a piezoelectric element is fixed to at least one surface of a diaphragm made of metal;
A cone diaphragm coupled to the piezoelectric diaphragm;
A printed wiring board electrically connected to the piezoelectric diaphragm via a plurality of electric wires;
A cover having a sound hole closed by the cone diaphragm;
A back cover coupled to the cover in such a manner that an outer peripheral end of the cone diaphragm is sandwiched between the cover and the cover;
A base that forms a case that is coupled to the cover and houses the piezoelectric diaphragm, the printed wiring board, and the back cover;
When viewed from the thickness direction of the printed wiring board, a part of the printed wiring board, a part of the cone diaphragm, and a part of the back cover are overlapped with each other,
The sound source device according to claim 1, wherein the back cover is provided with an electric wire holding convex portion for positioning the electric wire between the back cover and the base.   The sound source device according to claim 1, wherein in the printed wiring board, the connection portion of the electric wire is disposed at an end portion on a side close to the piezoelectric diaphragm.

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