BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piezoelectric sounding body that generates a certain sound by vibration of a piezoelectric vibrating plate.
2. Description of the Related Art
For example, in the likes of an automobile or various kinds of household electrical appliances, a piezoelectric sounding body is sometimes adopted as a sounding body that generates a buzzer sound or the like. The piezoelectric sounding body applies a cyclical voltage signal to a piezoelectric vibrating plate, thereby vibrating the piezoelectric vibrating plate and generating a specific sound (for example, a warning sound, and so on) that attracts the attention of a user, or the like.
In the piezoelectric sounding body, the piezoelectric vibrating plate is housed in a case, and a lead terminal connected to the piezoelectric vibrating plate passes through a through hole provided in the case and is thereby led out to the outside of the case (see Patent Document 1).
Patent Document 1: JP H11-52958 A
SUMMARY OF THE INVENTION
In a conventional piezoelectric sounding body, there occurred the problem that when an impact is applied to a portion led out to the outside of the case of the lead terminal, the impact is transmitted to a portion housed on the inside of the case of the lead terminal, and there occurs a positional misalignment of the lead terminal, or damage or a conductive malfunction of a joining portion between the lead terminal and another component (for example, the piezoelectric vibrating plate). The positional misalignment of the lead terminal or damage of the joining portion, and so on, sometimes change the likes of sound pressure relating to a sound generated by the piezoelectric sounding body, and quality improvement has become required from a viewpoint of reliability, durability, and so on, of the piezoelectric sounding body.
The present invention has been made in view of such circumstances. It is an object of the invention to provide a piezoelectric sounding body capable of preventing an external force applied to a portion arranged on the outside of a case of a conductive terminal from being transmitted to the inside of the case and a positional misalignment of a member on the inside of the case or a joining malfunction from occurring.
In order to achieve the above object, a piezoelectric sounding body according to the present invention comprises:
a piezoelectric vibrating plate;
a case housing the piezoelectric vibrating plate;
a first conductive terminal electrically connected to one electrode in the piezoelectric vibrating plate; and
a second conductive terminal electrically connected to the other electrode in the piezoelectric vibrating plate, wherein at least one of the first conductive terminal and the second conductive terminal including:
a first terminal portion arranged inside the case;
a second terminal portion arranged on the outside of the case; and
a third terminal portion arranged in a terminal insertion hole formed in the case to connect the first terminal portion and the second terminal portion, and the first terminal portion includes a sandwiching portion configured to sandwich part of the case between the first terminal portion and the second terminal portion.
The piezoelectric sounding body according to the present invention sandwiches part of the case by the first terminal portion arranged on the inside of the case and the second terminal portion arranged on the outside of the case, hence even if an external force such as an impact is applied to the second terminal portion, that external force can be preferably received by the case. Thus, even in the case when an external force is applied to the second terminal portion, it is possible to prevent problems such as the first terminal portion moving, or a joining portion between the first terminal portion and another component being damaged, and it is possible to prevent the likes of a change in sound pressure accompanying those problems, hence the piezoelectric sounding body according to the present invention displays high reliability and durability performance.
For example, the first terminal portion may include: a contacting part configured to extend in the same plane as the sandwiching portion and be fixed in a caulking manner so as to contact an inner wall surface of the case; and a contact-point part configured to connect the contacting part and the piezoelectric vibrating plate.
The contacting part that extends the same plane as the sandwiching portion is fixed to the inner wall surface of the case, whereby even if an external force such as an impact is applied to the second terminal portion, that external force can be more preferably received by the case, the external force can be prevented from being transmitted to a joining part, and connection between the piezoelectric vibrating plate and the joining part can be prevented from being damaged. Moreover, the contacting part is fixed in a caulking manner, hence fixing of the case and the contacting part is easy and has high reliability.
For example, the contact-point part may extend a direction crossing a first direction defined as an arrangement direction of the sandwiching portion and the contacting part when the first terminal portion is viewed from a normal direction of an arrangement surface of the sandwiching portion and the contacting part.
By the contact-point part extending in a direction intersecting the first direction, it is possible to increase a length from a portion fixed in a caulking manner to an edge of the contact-point part, whereby appropriate springiness can be provided to the contact-point part. Moreover, the problem of a caulking projection interfering with a movable range of the contact-point part to cause a defective product, can be reduced.
For example, the contacting part may be in contact with a portion of the inner wall surface positioned at one side to the terminal insertion hole, and the sandwiching portion may be in contact with a portion of the inner wall surface positioned at the other side to the terminal insertion hole.
The sandwiching portion sandwiches the case between itself and the second terminal portion and the contacting part is fixed in a caulking manner to the inner wall surface, hence in this kind of piezoelectric sounding body, the first terminal portion arranged on both sides sandwiching the terminal insertion hole is supported by the case on both sides. Thus, the case can preferably receive an external force transmitted via the second terminal portion and the third terminal portion, hence problems of a position of the first terminal portion being misaligned or connection between the contact-point part and the piezoelectric vibrating plate being released by the external force, can be reliably prevented.
For example, the contact-point part may have a shape configured to become narrower from the contacting part toward the piezoelectric vibrating plate.
Configuring the contact-point part to have a shape that narrows toward the piezoelectric vibrating plate side makes it possible for flexibility of the contact-point part to be raised, and for conduction to be secured in a state where vibration of the piezoelectric vibrating plate is not hindered. Moreover, even in the case when an external force that was unable to be received by the case has been transmitted to the contact-point part, the narrowed contact-point part elastically deforms, whereby the external force can be prevented from being transmitted to a more extreme portion than a deformed place, and the problem of damage, and so on, occurring in a joining portion between the contact-point part and the piezoelectric vibrating plate, can be prevented.
For example, a caulking projection configured to form a plurality of fixing holes on the contacting part and to fix the contacting part to the inner wall surface may be inserted into the fixing hole.
In the piezoelectric sounding body that has caulking projections inserted through a plurality of fixing holes formed in the contacting part, the problem of a fixed terminal rotating by an external force, and so on, can be effectively prevented. Moreover, when attaching a conductive terminal to the case, the conductive terminal can be simply arranged in a correct position merely by inserting the caulking projection prior to its edge being deformed, in the fixing hole of the contacting part, hence this kind of piezoelectric sounding body can be easily manufactured.
For example, the second terminal portion may include: a downside part configured to be parallel to the sandwiching portion and to contact an outer wall surface of the case; and a lateral part configured to be parallel to the third terminal portion and to contact the outer wall surface.
Such a conductive terminal of the piezoelectric sounding body has a shape that not only sandwiches the case between the sandwiching portion and the downside part, but sandwiches the case also between the third terminal portion and the lateral part, hence the first terminal portion excluding the joining part and the second terminal portion and third terminal portion reliably sandwich part of the case. In such a piezoelectric sounding body, even if an external force is applied to the second terminal portion, that external force can be more preferably received by the case, the external force can be prevented from being transmitted to the joining part, and connection between the piezoelectric vibrating plate and the joining part can be prevented from being damaged.
For example, a through hole corresponding to a shape of the sandwiching portion may be formed on the third terminal portion.
The conductive terminal having such a shape can be easily formed by mechanically processing a single metal plate, for example, and, moreover, does not have a joining portion resulting from welding or the like, hence has high strength and excellent durability.
For example, the case may include: a lower case where the first conductive terminal and the second conductive terminal are fixed; and an upper case configured to be fixed in a caulking manner to the lower case and to sandwich the piezoelectric vibrating plate between the upper case and the lower case.
The piezoelectric sounding body in which the piezoelectric vibrating plate is held sandwiched between an upper case and a lower case, and in which the upper case and the lower case are fixed in a caulking manner differs from the conventional technology adopting a method of fixing in which the upper case and the lower case are fitted using flexible deformation of the case, and is almost immune to joining of the upper case and the lower case being released, even when heat is applied. Thus, this kind of piezoelectric sounding body is capable of efficient mounting on a substrate, and so on, by surface mounting due to reflow, or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a piezoelectric sounding body according to an embodiment of the present invention.
FIG. 2 is an exploded cross-sectional view of the piezoelectric sounding body shown in FIG. 1.
FIG. 3 is a schematic plan view showing a state of a lower case and a conductive terminal of the piezoelectric sounding body shown in FIG. 1 as seen from above.
FIG. 4 is a plan view showing the lower case prior to assembly used for the piezoelectric sounding body shown in FIG. 1.
FIG. 5A is a plan view showing a first conductive terminal used for the piezoelectric sounding body shown in FIG. 1.
FIG. 5B is a plan view showing a second conductive terminal used for the piezoelectric sounding body shown in FIG. 1.
FIG. 6 is a schematic perspective view of the first conductive terminal shown in FIG. 5A.
FIG. 7 is a cross-sectional view showing an assembled state of an upper case, a piezoelectric vibrating plate, and the lower case.
FIG. 8A to FIG. 8D are a conceptual diagram explaining a step of attaching a conductive terminal to the lower case.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described below based on an embodiment shown in the drawings.
FIG. 1 is a schematic perspective view of a piezoelectric sounding body 10 according to an embodiment of the present invention. As shown in FIG. 1, the piezoelectric sounding body 10 includes a case 30 configured by an upper case 40 and a lower case 50. The case 30 houses a piezoelectric vibrating plate 20 shown in FIG. 2 and a first conductive terminal 60 and a second conductive terminal 70 that are electrically connected to electrodes of the piezoelectric vibrating plate 20. As shown in FIG. 1, other parts of the first conductive terminal 60 and the second conductive terminal 70 are exposed to the outside of the case 30.
FIG. 2 is an exploded cross-sectional view of the piezoelectric sounding body 10 shown in FIG. 1. The piezoelectric vibrating plate 20 has an outer shape of circular plate. The piezoelectric vibrating plate 20 has a two-layer structure in which a piezoelectric body 22 and a vibrating plate 24 both having a circular plate shape are concentrically stacked, and the vibrating plate 24 arranged upwardly has a larger diameter than the piezoelectric body 22 arranged downwardly.
The vibrating plate 24 functions as one electrode of the piezoelectric vibrating plate 20. The other electrode 22a of the piezoelectric vibrating plate 20 is formed on a lower surface of the piezoelectric body 22. Moreover, the vibrating plate 24 as one electrode and the other electrode 22a are insulated, and a voltage is applied to the piezoelectric body 22 via the vibrating plate 24 and the other electrode 22a. The piezoelectric body 22 is made of any material with an electrode formed on a piezoelectric material, and is configured, for example, by forming the electrode 22a, such as Ag, on the likes of ferroelectric ceramics, such as PZT (lead zirconate titanate). The vibrating plate 24 is also made of any material, such as metal material of brass, Ni alloy, or the like. Note that the vibrating plate 24 may be joined to the piezoelectric body 22 via a base electrode, such as Ag, formed on the surface of the piezoelectric body 22.
As shown in FIG. 1 and FIG. 2, the upper case 40 has a substantially hollow cylindrical outer shape where a sound emitting hole 42 is formed on its upper center. As shown in FIG. 2, an edge part of the sound emitting hole 42 configures a cylindrical part 44 protruding downwardly, and the cylindrical part 44 is arranged inside the upper case 40. An opening diameter of the sound emitting hole 42 or protrusion length of the cylindrical part 44 is properly adjusted based on the likes of a pitch of sound generated by the piezoelectric sounding body 10.
The upper case 40 has any diameter of its periphery, such as about 10 to 30 mm. Moreover, the upper case 40 has also any height, such as about 3 to 15 mm.
A contact projection 45 is formed along the circumferential direction of the lower end of the upper case 40. As shown in FIG. 7, which displays an assembled state of the upper case 40, the lower case 50, and the piezoelectric vibrating plate 20, the contact projection 45 of the upper case 40 fixes the piezoelectric vibrating plate 20 by pressing it onto a lower case step part 51 formed in the lower case 50. Note that FIG. 7 does not illustrate the first conductive terminal 60 or the second conductive terminal 70 shown in FIG. 2.
Engaging parts 46a and 46b projecting toward the outer diameter direction are formed at four places in an outer periphery of the upper case 40. An insertion hole for inserting a case caulking projection 56 provided on the lower case 50 is formed in the respective engaging parts 46a and 46b. The upper case 40 is fixed to the lower case 50 due to caulking by inserting the case caulking projection 56 into the insertion hole of the engaging parts 46a and 46b.
FIG. 4 is a plan view of the lower case 50. As shown in FIG. 4, the lower case 50 has a substantially rectangular outer shape when viewed from above. The four corners of the lower case 50 are provided with the case caulking projections 56 for fixing the upper case 40 to the lower case 50 in a caulking manner.
Guide parts 56a and 56b engaged with the engaging parts 46a and 46b of the upper case 40 are formed on the periphery of the four case caulking projections 56. The engaging parts 46a and 46b of the upper case 40 and the guide parts 56a and 56b of the lower case 50 have shape corresponding to each other. The upper case 40 and the lower case 50 are combined in a correct position, so that the engaging parts 46a and 46b of the upper case 40 are engaged with the guide parts 56a and 56b of the lower case 50, and the case caulking projections 56 of the lower case 50 are inserted through the insertion holes formed in the engaging parts 46a and 46b of the upper case 40.
At least one pair of the guide part 56b and the engaging part 46b of the corresponding four pairs of the guide parts 56a and 56b and the engaging parts 46a and 46b have a different shape from the other guide parts 56a and engaging parts 46a. This prevents the engaging parts 46a and 46b from engaging with the guide parts 56a and 56b when attempting to combine the upper case 40 and the lower case 50 in an incorrect position (see FIG. 4 and FIG. 7).
As shown in FIG. 4, a first terminal insertion hole 54a and a second terminal insertion hole 54b are formed on the bottom surface of the lower case 50. The first conductive terminal 60 (see FIG. 2 and FIG. 5A) passes through the first terminal insertion hole 54a. The second conductive terminal 70 (see FIG. 2 and FIG. 5B) passes through the second terminal insertion hole 54b. The first terminal insertion hole 54a and the second terminal insertion hole 54b penetrate the lower case 50 from a lower case inner wall surface 52 to a lower case outer wall surface 53, which is an outer wall surface of the lower case 50 (see FIG. 2).
The first terminal insertion hole 54a and the second terminal insertion hole 54b have a substantially rectangular opening shape, and are arranged substantially symmetrically to each other, having a center 50a of the lower case 50 as a symmetric axis. Terminal caulking projections 57a for fixing the first conductive terminal 60 to the lower case 50 are formed in an inner wall first portion 52a, which is the lower case inner wall surface 52 from the first terminal insertion hole 54a to the center 50a. A plurality (two in the embodiment) of the terminal caulking projections 57a is formed in the inner wall first portion 52a.
Moreover, a plurality of (four in the embodiment) auxiliary caulking projections 58a is formed on an opening edge at the side of the lower case inner wall surface 52 of the first terminal insertion hole 54a. The auxiliary caulking projections 58a in conjunction with the terminal caulking projections 57a fix the first conductive terminal 60 to the lower case 50.
A terminal caulking projection 57b for fixing the second conductive terminal 70 to the lower case 50 is formed on the lower case inner wall surface 52 from the second terminal insertion hole 54b to the center 50a. A plurality of auxiliary caulking projections 58b is formed on the lower case inner wall surface 52 along an opening edge of the second terminal insertion hole 54b. The number of the terminal caulking projections 57b and the auxiliary caulking projections 58b for fixing the second conductive terminal 70 is the same as the number of the terminal caulking projections 57a and the auxiliary caulking projections 58a for fixing the first conductive terminal 60. However, the number of the terminal caulking projections 57a and 57b and the auxiliary caulking projections 58a and 58b is not limited to the number shown in the embodiment.
As shown in FIG. 2, the lower case step part 51 for mounting a circumferential portion of the piezoelectric vibrating plate 20 is formed in the lower case 50. The lower case step part 51 is formed along a circumferential direction of the upper case 40, and has a planar shape corresponding to a shape of the contact projection 45 of the upper case 40. As shown in FIG. 4, the lower case step part 51 is divided by a notch 59 formed in the lower case 50, and hence is not continuous in the circumferential direction. The notch 59 is an air hole provided for being able to appropriately generate sound by the piezoelectric sounding body 10. This air hole has any shape and is positioned anywhere.
The upper case 40 and the lower case 50 can be manufactured by a resin material, such as a liquid crystal polyester resin, a phenol resin, and a polybutylene terephthalate resin. The upper case 40 and the lower case 50 are preferably manufactured by a heat resistant resin so as to be able to endure a thermal load during surface mounting, but are not limited.
As shown in FIG. 2, the first conductive terminal 60 has a first terminal portion 62, a second terminal portion 64, and a third terminal portion 66. The first terminal portion 62 is arranged inside the case 30 shown in FIG. 1. The second terminal portion 64 is arranged outside the case 30. The third terminal portion 66 is arranged in the first terminal insertion hole 54a formed in the lower case 50 of the case 30 to connect the first terminal portion 62 and the second terminal portion 64.
In an assembled state where the piezoelectric vibrating plate 20 is fixed to the lower case step part 51 (see FIG. 7), a terminal tip 62ca of the first conductive terminal 60 is electrically connected to the vibrating plate 24, which is one electrode of the piezoelectric vibrating plate 20. FIG. 3 shows a state where the first conductive terminal 60 and the second conductive terminal 70 are fixed to the lower case 50. The terminal tip 62ca of the first conductive terminal 60 is connected to a portion of the piezoelectric vibrating plate 20 where the vibrating plate 24 is visible from below. The terminal tip 62ca is fixed to the vibrating plate 24 using the likes of a conductive adhesive agent, for example, but the piezoelectric vibrating plate 20 and the first conductive terminal 60 are connected by any method.
FIG. 5A is a plan view of the first conductive terminal 60. The first terminal portion 62 of the first conductive terminal 60 has a contacting part 62a, a sandwiching portion 62b, and a contact-point part 62c. As shown in FIG. 2 and FIG. 6, the contacting part 62a extends in the same plane as the sandwiching portion 62b. As shown in FIG. 5A, a plurality (two in the embodiment) of fixing holes 62aa for inserting the terminal caulking projections 57a of the lower case 50 is formed on the contacting part 62a. As shown in FIG. 2 and FIG. 3, the contacting part 62a is fixed in a caulking manner by the terminal caulking projections 57a and the auxiliary caulking projections 58a so as to contact the lower case inner wall surface 52, which is an inner wall surface of the lower case 50.
As shown in FIG. 3, FIG. 5A, and FIG. 5B, the sandwiching portion 62b of the first terminal portion 62 is connected to one side of the contacting part 62a, is smaller than the contacting part 62a, and has a rectangular plate like outer shape. As shown in FIG. 2, the contacting part 62a contacts the inner wall first portion 52a of the lower case inner wall surface 52 positioned at the side of the center 50a (one side) with respect to the first terminal insertion hole 54a, and the sandwiching portion 62b contacts an inner wall second portion 52b of the lower case inner wall surface 52 positioned at the side of the periphery (the other side) with respect to the first terminal insertion hole 54a. Note that, as shown in FIG. 3, the auxiliary caulking projections 58a may fix the sandwiching portion 62b in addition to the contacting part 62a of the first terminal portion 62 to the lower case 50 in a caulking manner.
As shown in FIG. 2, the second terminal portion 64 is arranged on the lower case outer wall surface 53 located opposite to the inner wall second portion 52b so as to face the lower case outer wall surface 53. At least part of the second terminal portion 64 contacts the lower case outer wall surface 53, and the sandwiching portion 62b contacting the inner wall second portion 52b sandwiches part of the lower case 50 between itself and the second terminal portion 64.
As shown in FIG. 2, the contact-point part 62c extends upwardly with respect to a plane in which the contacting part 62a and the sandwiching portion 62b are arranged. As shown in FIG. 5, a base end of the contact-point part 62c is connected to the contacting part 62a, and the terminal tip 62ca, which is a tip of the contact-point part 62c, is fixed to the piezoelectric vibrating plate 20 shown in FIG. 2. Thus, the contact-point part 62c connects the contacting part 62a and the piezoelectric vibrating plate 20.
As shown in FIG. 2 and FIG. 5, a bend portion is formed at two places in the contact-point part 62c. Moreover, as shown in FIG. 2, in the first terminal portion 62, when an arrangement direction of the sandwiching portion 62b and the contacting part 62a is assumed to be a first direction and the first terminal portion 62 is viewed in plane from a normal direction to a placement surface of the sandwiching portion 62b and the contacting part 62a, the contact-point part 62c extends in a direction intersecting the first direction. Furthermore, the contact-point part 62c has a shape that narrows from its base end on a side of the contacting part 62a to the terminal tip 62ca on a side of the piezoelectric vibrating plate 20.
As shown in FIG. 6, the third terminal portion 66 is connected to the contacting part 62a of the first terminal portion 62. The third terminal portion 66 is connected to the same side of the contacting part 62a as the side where the sandwiching portion 62b is connected to the contacting part 62a, but the third terminal portion 66 is bent downwardly with respect to the contacting part 62a, whereas the sandwiching portion 62b is arranged in the same plane as the contacting part 62a.
As shown in FIG. 6, a through hole 66a corresponding to a shape of the sandwiching portion 62b is formed on the third terminal portion 66. Note that an entirety of the through hole 66a may be formed in the third terminal portion 66, and that part of the through hole 66a may be continuous to the second terminal portion 64.
As shown in FIG. 6, the third terminal portion 66 connects the first terminal portion 62 and the second terminal portion 64. As shown in FIG. 2, the third terminal portion 66 is arranged in the first terminal insertion hole 54a of the lower case 50.
As shown in FIG. 2, a downside part 64a of the second terminal portion 64 bent to connect to the third terminal portion 66 is parallel to the sandwiching portion 62b, and at least part of the downside part 64a contacts the lower case outer wall surface 53. As shown by the dotted lines in FIG. 4, a downside recess 53a is formed on a surface facing downwardly of the lower case outer wall surface 53, and the downside part 64a of the third terminal portion 66 is arranged in the downside recess 53a.
An end on an opposite side to a side connected to the third terminal portion 66 in the second terminal portion 64 is bent upwardly from the state shown in FIG. 2 and configures a lateral part 64b as shown in FIG. 1. As shown in FIG. 2, a lateral recess 53b is formed on a surface facing laterally of the lower case outer wall surface 53, and the lateral part 64b of the third terminal portion 66 is arranged on the lateral recess 53b. The lateral part 64b is substantially parallel to the third terminal portion 66 and sandwiches part of the lower case 50 between itself and the third terminal portion 66.
As shown in FIG. 2, the second conductive terminal 70, similarly to the first conductive terminal 60, also includes: a first terminal portion 72 arranged on the inside of the case 30; a second terminal portion 74 arranged on the outside of the case 30; and a third terminal portion 76 that connects the first terminal portion 72 and the second terminal portion 74 and is arranged in the second terminal insertion hole 54b formed in the lower case 50 of the case 30.
FIG. 5B is a plan view of the second conductive terminal 70. As understood from a comparison between FIG. 5A and FIG. 5B, the second conductive terminal 70 has common characteristics with the first conductive terminal 60 in many respects. Thus, the second conductive terminal 70 will be explained mainly in terms of differences from the first conductive terminal 60, and common points with the conductive terminal 60 will not be explained.
In the assembled state where the piezoelectric vibrating plate 20 is fixed to the lower case step part 51 (see FIG. 7), a terminal tip 72ca of the second conductive terminal 70 is electrically connected to the other electrode 22a of the piezoelectric vibrating plate 20. As shown in FIG. 3, the terminal tip 72ca of the second conductive terminal 70 is arranged nearer to the center 50a than the terminal tip 62ca of the first conductive terminal 60, and is connected to a portion of the piezoelectric vibrating plate 20 where the vibrating plate 24 is covered from below by the piezoelectric body 22. The terminal tip 72ca of the second conductive terminal 70 is fixed to the other electrode 22a using the likes of a conductive adhesive agent.
As shown in FIG. 5B, fixing holes 72aa, where the terminal caulking projections 57a of the lower case 50 are inserted, are also formed on the second conductive terminal 70, and the second conductive terminal 70 is also fixed in a caulking manner by the terminal caulking projections 57b and the auxiliary caulking projections 58b (see FIG. 3).
The first conductive terminal 60 and the second conductive terminal 70 may be produced using the likes of a good conductor metal, for example, phosphor bronze, but the first conductive terminal 60 and the second conductive terminal 70 are made of any material. Moreover, the first conductive terminal 60 and the second conductive terminal 70 may be applied with the likes of Au plating, Ni plating, or Sn plating.
The piezoelectric sounding body 10 shown in FIG. 1 is manufactured by the following steps, for example.
First, in a first step, the lower case 50 shown in FIG. 4 and the first conductive terminal 60 and second conductive terminal 70 shown in FIG. 5 are prepared, and the first conductive terminal 60 and the second conductive terminal 70 are attached to the lower case 50. Note that the upper case 40 and the lower case 50 are manufactured by resin molding such as injection molding, for example, and the first conductive terminal 60 and the second conductive terminal 70 are manufactured by mechanically processing a flat metal plate whose surface has been plated, for example.
FIG. 8 is a conceptual diagram showing how the first conductive terminal 60 is attached to the lower case 50. In attachment of the first conductive terminal 60 to the lower case 50, first, as shown in FIG. 8A, the first conductive terminal 60 is passed through the first terminal insertion hole 54a of the lower case 50 in a state where the first conductive terminal 60 is inclined. Next, as shown in FIG. 8B, while bringing the sandwiching portion 62b into contact with the lower case inner wall surface 52, inclination of the first conductive terminal 60 is reduced, and the contacting part 62a is brought closer to the lower case inner wall surface 52.
Next, as shown in FIG. 8C, while passing the terminal caulking projection 57a through the fixing hole 62aa formed in the contacting part 62a, inclination of the first conductive terminal 60 is further reduced. Finally, as shown in FIG. 8D, the contacting part 62a is brought into contact with the lower case inner wall surface 52, whereby attachment of the first conductive terminal 60 to the lower case 50 is completed. The second conductive terminal 70, after having been passed through the second terminal insertion hole 54b, is also attached to the lower case 50 similarly to the first conductive terminal 60.
Next, in a second step, the first conductive terminal 60 and the second conductive terminal 70 are fixed in a caulking manner to the lower case 50. Specifically, tips of the terminal caulking projections 57a and 57b of the lower case 50 are heated and thereby deformed so as to be larger than the fixing holes 62aa and 72aa of the first conductive terminal 60 and the second conductive terminal 70. In addition, the auxiliary caulking projections 58a and 58b are heated and thereby deformed, such that as shown in FIG. 3, parts of the auxiliary caulking projections 58a and 58b contact upper surfaces of the contacting parts 62a and 72a and the sandwiching portions 62b and 72b. As a result, as shown in FIG. 4, an intermediate product in which the first conductive terminal 60 and the second conductive terminal 70 are fixed in a caulking manner to the lower case 50, is produced.
Next, in a third step, the intermediate product produced in the second step, the piezoelectric vibrating plate 20, and the upper case 40 are prepared, and these three members are assembled as shown in FIG. 2 and FIG. 7. The piezoelectric vibrating plate 20 is produced by joining the piezoelectric body 22 where the electrode 22a is formed to the vibrating plate 24. The piezoelectric body 22 and the vibrating plate 24 may be joined by adhering the two with the likes of an epoxy adhesive agent, for example, but the piezoelectric body 22 and the vibrating plate 24 are joined by any method.
In the third step, the terminal tips 62ca and 72ca of the first conductive terminal 60 and the second conductive terminal 70 in the prepared intermediate product are coated with a conductive adhesive agent. Next, the piezoelectric vibrating plate 20 is brought close from above the intermediate product and placed in the lower case step part 51 of the lower case 50, further, the upper case 40 is brought close to the lower case 50 from above the piezoelectric vibrating plate 20, and the engaging parts 46a and 46b are engaged with the guide parts 56a and 56b of the lower case 50 as shown in FIG. 7, thereby assembling the upper case 40 and the lower case 50.
Note that prior to assembly of the upper case 40 and the lower case 50, at least one of a peripheral part of the upper surface of the piezoelectric vibrating plate 20 and the contact projection 45 of the upper case 40 may be coated with a resin such as silicone. After the third step, the coated silicone is cured by heating, whereby the problem of a gap being formed between the piezoelectric vibrating plate 20 and the contact projection 45 can be prevented, and the problem of the piezoelectric sounding body 10 becoming unable to generate a desired sound can be prevented.
In a fourth step, an edge of the case caulking projection 56 is heated and thereby deformed so as to be larger than a diameter of the insertion hole formed in the engaging parts 46a and 46b, whereby the upper case 40 is fixed to the lower case 50. Moreover, when the upper case 40 is fixed to the lower case 50, the piezoelectric vibrating plate 20 is sandwiched by the upper case 40 and the lower case 50 and fixed to the case 30. Furthermore, by the conductive adhesive agent coated on the terminal tips 62ca and 72ca of the first conductive terminal 60 and the second conductive terminal 70 being cured after being brought into contact with the piezoelectric vibrating plate 20, the terminal tips 62ca and 72ca and the piezoelectric vibrating plate 20 are connected.
After going through such steps, the piezoelectric sounding body 10 shown in FIG. 1 is manufactured. Note that a step in which parts of the second terminal portions 64 and 74 in the first conductive terminal 60 and second conductive terminal 70 are bent upwards to configure the lateral part 64b shown in FIG. 1 may be performed at the end of the first step, and moreover, may be performed in the second through fourth steps performed after the first step.
As shown in FIG. 2 and FIG. 3, the piezoelectric sounding body 10 sandwiches part of the case 30 by the sandwiching portions 62b and 72b of the first and second conductive terminals 60 and 70 arranged on the inside of the case 30 and the second terminal portions 64 and 74 arranged on the outside of the case 30. In addition, the contacting part 62a and the sandwiching portion 62b arranged on both sides sandwiching the terminal insertion holes 54a and 54b are both supported by the lower case inner wall surface 52. As a result, an external force applied to the second terminal portions 64 and 74 is received by the case 30, and the problem of the conductive terminals 60 and 70 moving inside the case 30 by the external force can be prevented. Thus, in the piezoelectric sounding body 10, the problem of an electrical connection state between the piezoelectric vibrating plate 20 and the conductive terminals 60 and 70 deteriorating due to the conductive terminals 60 and 70 moving inside the case 30 by an external force, can be prevented. Moreover, even when an external force is applied, it is difficult for a fixed state of the conductive terminals 60 and 70 to the case 30 to change, and hence the piezoelectric sounding body 10 displays high reliability and durability performance.
Moreover, as shown in FIG. 2, the piezoelectric sounding body 10 has a shape that not only sandwiches the lower case 50 between the sandwiching portions 62b and 72b of the first terminal portions 62 and 72 and the downside parts 64a and 74a of the second terminal portions 64 and 74, but sandwiches the lower case 50 also between the third terminal portions 66 and 76 and the lateral part 64b of the second terminal portions 64 and 74. Thus, in the piezoelectric sounding body 10, many portions of the conductive terminals 60 and 70, such as the first terminal portions 62 and 72 excluding the contact-point parts 62c and 72c, the second terminal portions 64 and 74, and the third terminal portions 66 and 76, contact the case 30 from a variety of directions, and hence an external force applied to the second terminal portions 64 and 74 is preferably received by the case 30.
As shown in FIG. 3, in the piezoelectric sounding body 10, the contacting parts 62a and 72a extending in the same plane as the sandwiching portions 62b and 72b are fixed to the lower case inner wall surface 52, and hence an external force applied to the second terminal portions 64 and 74 can be preferably received by the lower case 50. Thus, the following problem can be prevented: on the inside of the case 30, an external force is transmitted to a joining part of the contact-point parts 62c and 72c extending upwardly from the contacting parts 62a and 72a and the piezoelectric vibrating plate 20, and the joining part is thereby damaged. Moreover, since the contacting parts 62a and 72a are fixed in a caulking manner to the lower case 50, the lower case 50 and the contacting parts 62a and 72a are fixed with simplicity and high reliability.
As shown in FIG. 3, in the piezoelectric sounding body 10, the conductive terminals 60 and 70 are fixed in a caulking manner by the terminal caulking projections 57a and 57b being inserted into the plurality of fixing holes 62aa and 72aa formed in the contacting parts 62a and 72a, and hence the conductive terminals 60 and 70 can be effectively prevented from rotating due to an external force or the like. When attaching the conductive terminals 60 and 70 to the lower case 50, the conductive terminals 60 and 70 can be simply arranged in a correct position merely by inserting the terminal caulking projections 57a and 57b prior to having their tips deformed, into the fixing holes 62aa and 72aa of the contacting parts 62a and 72a, and hence this kind of piezoelectric sounding body 10 can be easily manufactured.
As shown in FIG. 5, in the piezoelectric sounding body 10, the contact-point parts 62c and 72c of the conductive terminals 60 and 70 have a shape that becomes narrower toward the terminal tips 62ca and 72ca. Thus, the contact-point parts 62c and 72c have a high flexibility, and conduction can be secured in a state where vibration of the piezoelectric vibrating plate 20 is unhindered. Moreover, even in the case when an external force that was unable to be received by the case 30 has been transmitted to the contact-point parts 62c and 72c, the narrowed contact-point parts 62c and 72c elastically deform, whereby the external force can be prevented from being transmitted farther to the tip side than a deformed place, and the problem of damage, and so on, occurring in a joining portion between the contact-point parts 62c and 72c and the piezoelectric vibrating plate 20, can be prevented.
As shown in FIG. 5, in the piezoelectric sounding body 10, by the contact-point parts 62c and 72c extending in a direction intersecting the first direction, a length from the portion fixed in a caulking manner to the terminal tips 62ca and 72ca can be increased, whereby appropriate springiness can be provided to the contact-point part 62c. Moreover, the problem of the terminal caulking projections 57a and 57b interfering with a movable range of the contact-point parts 62c and 72c to cause a defective product, can be reduced.
As shown in FIG. 6, the third terminal portions 66 and 76 of the conductive terminals 60 and 70 have formed therein the through hole 66a corresponding to a shape of the sandwiching portions 62b and 72b, and such conductive terminals 60 and 70 can be easily formed by mechanically processing a single metal plate. Such conductive terminals 60 and 70 do not have a joining portion resulting from the likes of welding or adhesion, hence have high strength and excellent durability.
As above, the piezoelectric sounding body according to the present invention was described showing an embodiment. However, the technical scope of the present invention is not limited to the piezoelectric sounding body 10 according to the embodiment, and it goes without saying that various modified examples altering the configuration of part of the piezoelectric sounding body 10 are also included in the technical scope of the invention. For example, shapes of the upper case 40 and the lower case 50, shapes of the conductive terminals 60 and 70, the numbers and positions of the terminal caulking projections 57a and 57b, and so on, can be changed according to design conditions, and so on.
In addition, for example, relative positions of the first terminal insertion hole 54a and the terminal caulking projection 57a and relative positions of the second terminal insertion hole 54b and the terminal caulking projection 57b may be made different. In this case, formation positions of the fixing holes 62aa and 72aa in the conductive terminals 60 and 70 are also made different for the first conductive terminal 60 and the second conductive terminal 70, based on the relative positions of the terminal insertion holes 54a and 54b and the terminal caulking projections 57a and 57b. By adopting such a shape, the problem that during assembly, the first conductive terminal 60 and the second conductive terminal 70 end up being assembled arranged in a mistaken position, can be prevented.
DESCRIPTION OF THE NUMERALS
10 . . . piezoelectric sounding body
20 . . . piezoelectric vibrating plate
22 . . . piezoelectric body
22
a . . . other electrode
24 . . . vibrating plate
30 . . . case
40 . . . upper case
42 . . . sound emitting hole
44 . . . cylindrical part
45 . . . contact projection
46
a, 46b . . . engaging part
50 . . . lower case
50
a . . . center
51 . . . lower case step part
52 . . . lower case inner wall surface
52
a . . . inner wall first portion
52
b . . . inner wall second portion
53 . . . lower case outer wall surface
53
a . . . downside recess
53
b . . . lateral recess
54
a, 54b . . . terminal insertion hole
56 . . . case caulking projection
56
a, 56b . . . guide part
57
a, 57b . . . terminal caulking projection
58
a, 58b . . . auxiliary caulking projection
59 . . . notch
60, 70 . . . conductive terminal
62, 72 . . . first terminal portion
62
a, 72a . . . contacting part
62
aa, 72aa . . . fixing hole
62
b, 72b . . . sandwiching portion
62
c, 72c . . . contact-point part
62
ca, 72ca . . . terminal tip
64, 74 . . . second terminal portion
64
a, 74a . . . downside part
64
b . . . lateral part
66 . . . third terminal portion
66
a . . . through hole
Patent Grant
10277967
