JP7460343B2 - Transducer - Google Patents

Description

The present invention relates to transducers.

Conventionally, transducers that transmit or receive sound waves or ultrasonic waves are known. Transducers are used, for example, as speakers that transmit sound waves, and are installed in earphones, wearable terminals, and the like.

For example, Patent Document 1 discloses a sound generating device suitable for earphones. This sound generating device includes a coil that generates a magnetic field and a magnet that interacts with the magnetic field generated by the coil to vibrate a diaphragm.

Speakers that use a coil and a magnet require current to flow through the coil to generate a magnetic field, resulting in high power consumption. Therefore, a speaker using a piezoelectric element configured by sandwiching a piezoelectric film from both sides between a pair of electrodes is also attracting attention (for example, see Patent Document 2). This type of speaker is manufactured using MEMS (Micro Electro Mechanical Systems), which is a semiconductor manufacturing technology that realizes microfabrication.

JP 2018-170592 A JP 2012-105170 A

However, because speakers manufactured using MEMS have minute shapes, they tend to have a fragile structure. As a result, they can be damaged by external shocks or thermal stress.

The present invention has been made in view of such problems, and its purpose is to provide a transducer that can suppress the occurrence of damage.

In order to solve such problems, the transducer according to the present invention includes a membrane support portion including a cylindrical inner circumferential surface forming a hollow portion, and a membrane supporting portion that is connected to the inner circumferential surface over the entire circumference of the inner circumferential surface. A piezoelectric element is provided with a vibrating membrane that can be displaced in the thickness direction, a piezoelectric membrane sandwiched between a pair of electrodes, and is laminated on the vibrating membrane, and the vibrating membrane and the piezoelectric element are laminated. It has a dividing slit that penetrates the vibrating body in the thickness direction and divides the vibrating body into a plurality of vibration regions. The inner peripheral surface has a polygonal shape in which the hollow part is a prism with chamfered corners, and the cylindrical inner peripheral surface has a plurality of flat parts corresponding to the flat parts of the prism and a chamfered part of the prism. and corresponding corners . The split slit includes a main slit extending from the center of the diaphragm toward the corner, and a sub-slit extending from the connecting part where the corner and the plane part connect to the end of the main slit on the corner side. It has a slit part.

The present invention provides a transducer with a structure that is resistant to breakage.

FIG. 1 is a top view of a transducer according to a first embodiment. FIG. 2 is a sectional view taken in the direction of the arrow in FIG. FIG. 3A is an enlarged top view showing the structure of a dividing slit located at a corner of the inner circumferential surface. FIG. 3B is a diagram illustrating a modification of the structure shown in FIG. 3A. FIG. 4 is a top view of the transducer according to the second embodiment. FIG. 5 is a top view of the transducer according to the third embodiment. FIG. 6 is a top view of the transducer according to the first modification. FIG. 7 is a top view of a transducer according to a second modification. FIG. 8 is a top view of a transducer according to a third modification. FIG. 9A is an enlarged view showing a main part of the transducer shown in FIG. FIG. 9B is a diagram illustrating a modified example of the structure shown in FIG. 9A. FIG. 10 is a cross-sectional view of a transducer according to a fourth modified example. FIG. 11A is an enlarged view showing a main part of the transducer shown in FIG. FIG. 11B is a diagram illustrating a modified example of the structure shown in FIG. 11A. FIG. 11C is a diagram illustrating a modified example of the structure shown in FIG. 11A. FIG. 12A is an enlarged cross-sectional view showing a main part of a transducer according to a fifth modified example. FIG. 12B is a diagram illustrating a modification of the structure shown in FIG. 12A. FIG. 12C is a diagram illustrating a modified example of the structure shown in FIG. 12A. FIG. 13 is a top view showing an enlarged main part of a transducer according to a sixth modification. FIG. 14 is a top view of a transducer according to the fourth embodiment. FIG. 15 is a cross-sectional view taken along the arrow direction of FIG. FIG. 16 is a cross-sectional view taken along the arrow direction of FIG. FIG. 17A is a diagram illustrating a modified example of the structure shown in FIG. FIG. 17B is a diagram illustrating a modification of the structure shown in FIG. 16. FIG. 18 is a top view of the transducer according to the fifth embodiment. FIG. 19 is a cross-sectional view taken along the arrow direction of FIG. FIG. 20 is a top view of the transducer according to the sixth embodiment. FIG. 21 is a sectional view taken in the direction of arrows in FIG. 20. FIG. 22 is an enlarged top view of the area surrounded by the dashed line in FIG. 20. FIG. FIG. 23 is a top view of the transducer according to the seventh embodiment. FIG. 24 is a sectional view taken in the direction of arrows in FIG. 23.

Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same parts are denoted by the same reference numerals and the description thereof will be omitted.

(First embodiment)
The configuration of a transducer 1 according to this embodiment will be described with reference to FIGS. 1 to 3. The transducer 1 according to this embodiment is mainly composed of a piezoelectric element 10 and a membrane body 15. In the following description, the vertical direction is defined based on the state of the transducer 1 shown in FIG. 2, but the direction in which the transducer 1 is used is not limited.

The piezoelectric element 10 includes a pair of electrodes 11 and 12 and a piezoelectric film 13 sandwiched between the pair of electrodes 11 and 12. The pair of electrodes 11 and 12 and the piezoelectric film 13 have a shape corresponding to the shape of a vibrating film 16, which will be described later, and have a square shape in the example shown in FIGS. 1 to 3.

Each of the pair of electrodes 11, 12 is formed from a thin film of a conductive metal such as aluminum or copper. One electrode 11 is located on the upper side of the piezoelectric film 13 and is connected to an electrode pad 11a, which is a circuit pattern for applying a drive voltage to the electrode 11. The other electrode 12 is located on the lower side of the piezoelectric film 13 and is connected to an electrode pad 12a, which is a circuit pattern for applying a drive voltage to the electrode 12.

The piezoelectric film 13 is made of, for example, a lead zirconate titanate (PZT) film. For the piezoelectric film 13, other than lead zirconate titanate, aluminum nitride (AlZ), zinc oxide (ZnO), lead titanate (PbTiO ₃ ), or the like can be used.

The membrane body 15 is composed of a vibration membrane 16 and a membrane support portion 17. The membrane body 15 is composed of, for example, silicon (Si). The vibration membrane 16 and the membrane support portion 17 are integrally formed by etching the underside of the membrane body 15.

The vibrating membrane 16 is made of a thin film, and is configured to be movable in the film thickness direction, that is, in the normal direction to the vibrating membrane 16 (perpendicular to the plane of the paper in FIG. 1, vertical direction in the plane of the paper in FIG. 2). The vibrating membrane 16 has a substantially rectangular shape when viewed from a plane parallel to the vibrating membrane 16.

The membrane support portion 17 has a square cylindrical inner peripheral surface forming a cavity (hollow portion) 18 . The diaphragm 16 is connected to the inner peripheral surface of the diaphragm support 17 over its entire circumference so that the diaphragm 16 is inscribed therein, so that the periphery of the diaphragm 16 is supported by the diaphragm support 17 . The vibrating membrane 16 is connected to the upper end of the membrane support section 17, and the upper side of the cavity 18 is closed by the vibrating membrane 16.

The inner peripheral surface is composed of four flat surfaces 17a and four corners 17b connecting adjacent flat surfaces 17a. Each corner 17b has a chamfered shape, not a shape corresponding to the interior angle of a rectangle. The chamfered shape of the corners 17b is formed in a straight line when viewed in a plane parallel to the vibration membrane 16, and the end of the flat surface 17a is connected to the end of the chamfered corner 17b. By connecting adjacent flat surfaces 17a via the chamfered corners 17b, the flat surface 17a and the corners 17b are connected at an angle (obtuse angle) larger than the angle formed by the adjacent flat surfaces 17a (the interior angle of a rectangle). In addition, when viewed in a plane parallel to the vibration membrane 16, the corners 17b may be formed by combining multiple straight lines or by a curved line, in addition to being formed by one straight line.

The transducer 1 also has a dividing slit 2. The dividing slit 2 is a cut that penetrates the vibration body, which is a laminate of a piezoelectric element 10 and a vibration membrane 16, in the thickness direction. The dividing slit 2 divides the vibration body into multiple vibration regions 100.

The dividing slit 2 has a main slit portion 2a that extends from the center of the vibration membrane 16 toward the corner portion 17b. In this embodiment, since the inner peripheral surface is rectangular, the dividing slit 2 has four main slit portions 2a. The four main slit portions 2a divide the vibrating body, which is a laminate of the piezoelectric element 10 and the vibration membrane 16, into four vibration regions 100.

Each of the divided diaphragms 16 has a cantilever shape that extends from the diaphragm support 17 toward the center of the diaphragm 16. The tip of each diaphragm 16 is configured as a free end.

Further, as shown in FIG. 3A, the divided slit 2 includes a sub-slit portion 2b. The sub slit portion 2b extends from the connecting portion where the corner portion 17b and the flat portion 17a are connected, that is, the corner between the corner portion 17b and the flat portion 17a, to the end of the main slit portion 2a on the corner portion 17b side. Extending. Since the corners are present on both sides of the corner portion 17b, two sub-slit portions 2b are provided for one main slit portion 2a.

For example, when the end of the main slit part 2a reaches the corner part 17b, as shown in FIG. 3A, the sub slit part 2b is formed in a straight line, and the main slit part 2a. However, the main slit portion 2a does not need to reach the corner portion 17b. In this case, as shown in FIG. 3B, the sub slit section 2b is connected to the main slit section 2a so as to form a Y shape. Note that the sub slit portion 2b may be formed in a shape other than a straight line. For example, when the corner portion 17b is formed by combining a plurality of straight lines or is formed from a curved line when viewed from a plane parallel to the vibrating membrane 16, the sub slit portion 2b has a shape along the corner portion 17b. It may be formed by

Note that in order to prevent the electrodes 11 and 12 from being separated by the dividing slit 2, wiring for interconnecting the electrodes 11 and 12 located in the adjacent vibration regions 100 is provided at a position corresponding to the corner 17b. A section has been established.

In the transducer 1 configured as described above, a piezoelectric element 10 is provided on the vibration membrane 16 of the membrane body 15. That is, a lower electrode 12, a piezoelectric membrane 13, and an upper electrode 11 are layered in this order on the vibration membrane 16. When a driving voltage is applied to each of the pair of electrodes 11, 12, a potential difference is generated between the pair of electrodes 11, 12. This potential difference displaces the vibration membrane 16. Specifically, the tip side of the divided vibration membrane 16 is displaced so as to be warped.

By repeatedly applying a driving voltage to the pair of electrodes 11 and 12, the vibrating membrane 16 alternately repeats upward displacement and downward displacement. The vibration of the vibrating membrane 16 causes the air around the vibrating membrane 16 to vibrate, and the vibration of the air is output as a sound wave.

As described above, in this embodiment, the inner circumferential surface forming the cavity 18 has a rectangular shape in which the four plane parts 17a are connected via the chamfered corners 17b. The divided slit 2 includes a main slit part 2a extending from the center of the vibrating membrane 16 toward the corner part 17b, and a corner in the main slit part 2a from a connecting part (corner) where the corner part 17b and the flat part 17a are connected. It has a sub-slit part 2b extending to the end on the part 17b side.

According to this configuration, since the corner portion 17b of the inner circumferential surface is chamfered, the angle at which the flat portion 17a connects to the corner portion 17b becomes large. Thereby, stress concentrated on the corner portion 17b can be alleviated. As a result, the strength of the membrane support portion 17 can be increased.

When the corner portion 17b is chamfered, the connection portion between the divided vibrating membrane 16 and the membrane support portion 17 includes a straight line along one plane portion 17a and a straight line along the corner portion 17b, and is curved. It has a shape. Since there is a bending point (corner) between the flat part 17a and the corner part 17b, if the divided vibrating membrane 16 is displaced, stress will be concentrated at the bending point, and cracks may occur. be.

Therefore, in this embodiment, the sub-slit portion 2b is connected from the end of the main slit portion 2a to the corner. As a result, the connection portion between the divided vibration membrane 16 and the membrane support portion 17 is composed only of a straight line region corresponding to the flat portion 17a. Even if the vibration membrane 16 is displaced, the concentration of stress at a specific location can be suppressed. As a result, the strength of the vibration membrane 16 and the membrane support portion 17 can be increased, thereby suppressing the occurrence of breakage.

In the above-described embodiment, the inner peripheral surface forming the cavity 18 is configured in a quadrangular shape. However, the inner peripheral surface may be configured in any polygonal shape, for example, in a hexagonal or octagonal, or in a pentagonal or heptagonal shape.

(Second embodiment)
With reference to FIG. 4, a transducer 1 according to a second embodiment will be described. The transducer 1 according to the second embodiment differs from the transducer 1 according to the first embodiment in the configuration of the piezoelectric element 10. Description of contents that overlap with those of the first embodiment will be omitted, and the following description will focus on the differences.

The piezoelectric element 10 includes a piezoelectric slit 14 that penetrates the piezoelectric element 10 in the thickness direction. A piezoelectric slit 14 is provided for each vibration region 100. Specifically, the piezoelectric slit 14 extends from the plane part 17a to the dividing slit 2 (main slit part 2a) along the vertical direction of the plane part 17a. Each vibration region 100 is divided into a plurality of small regions by the piezoelectric slit 14 . Then, each small region becomes discontinuous in a direction parallel to the plane portion 17a (lateral direction).

The displacement of the diaphragm 16 divided by the dividing slits 2 increases from the flat portion 17a toward the tip. Ideally, when the diaphragm 16 is viewed in the horizontal direction, the displacement is the same at every position. However, as the diaphragm 16 repeatedly vibrates, it may begin to warp in the horizontal direction, causing distortion in the diaphragm 16.

In this embodiment, since the vibrating membrane 16 is laterally divided by the piezoelectric slits 14, it is possible to suppress the occurrence of horizontal warpage in the vibrating membrane 16. This suppresses the occurrence of distortion in the vibrating membrane 16 and allows the vibrating membrane 16 to vibrate appropriately.

Although four piezoelectric slits 14 are provided for one vibration region 100, it is sufficient that one or more piezoelectric slits 14 are provided. Further, the number of piezoelectric slits 14 may be different for each vibration region 100.

Third Embodiment
A transducer 1 according to a third embodiment will be described with reference to Fig. 5. The transducer 1 according to the third embodiment differs from the transducer 1 according to the first embodiment in the connection form between the electrodes 11, 12 and the electrode pads 11a, 12a. The connection form between the electrode 11 and the electrode pad 11a will be described below, but the same is true for the connection form between the electrode 12 and the electrode pad 12a. Also, a description of the contents that overlap with the first embodiment will be omitted, and the description will focus on the differences.

The electrode pads 11a are provided for each vibration region 100 divided by the dividing slits 2. Specifically, four electrode pads 11a are provided to connect to the upper electrodes 11. One electrode pad 11a is provided for each vibration region 100, and each electrode pad 11a is connected to the electrode 11 of the corresponding vibration region 100.

If an external force is applied and distortion occurs in the membrane 15, a crack may occur at the end of the dividing slit 2, and this crack may extend to the electrode 11. For example, if a crack occurs in each of the opposing corners 17b, the electrode 11 may be divided into two, cutting off the current path. This makes it impossible to drive the transducer 1.

In this regard, according to the present embodiment, electrode pads 11a are prepared for each of the four divided regions 100. Therefore, the electrode 11 can be connected to the electrode pad 11a for each of the four vibration regions 100. Even in a case where the electrode 11 is divided into two, the driving voltage can be continued to be applied to each divided region. Thereby, the operation of the transducer 1 can be continued.

Note that in this embodiment, one electrode pad 11a is provided for one vibration region 100. However, a pair of electrode pads 11a may be provided for one vibration region 100. As a result, the electrode 11 and the pair of electrode pads 11a are connected in each vibration region 100, so even if the electrode 11 is separated by a crack, the vibrating membrane 16 can be vibrated in each individual vibration region 100. can.

Modifications applicable to each of the embodiments described above will be described below. Note that the modifications shown below are applicable to any of the first to third embodiments unless otherwise specified.

(First Modification)
A transducer 1 according to a first modified example will be described with reference to Fig. 6. In this first modified example, the piezoelectric element 10 has an opening 20 penetrating the piezoelectric element 10 in the thickness direction in a central region corresponding to the center of the vibration membrane 16. In Fig. 6, the opening 20 is formed in a rectangular shape, similar to the vibration membrane 16. In other words, the piezoelectric element 10 is not provided in the central region of the vibration membrane 16, and the piezoelectric element 10 is provided only in an outer region located outside the opening 20.

When the free end side of the divided vibrating membrane 16 is warped, a gap is generated in the thickness direction of the vibrating membrane 16. Since air moves through this gap, air leakage occurs when the air is vibrated. According to the configuration of the first modification, warping of the free end side of the vibrating membrane 16 can be suppressed. This makes it possible to suppress the movement of air caused by warping of the vibrating membrane 16, so that the air can be vibrated efficiently.

(Second Modification)
A transducer 1 according to a second modified example will be described with reference to Fig. 7. In this second modified example, the dividing slit 2 further includes a third slit portion 2d that divides the vibrating body in which the vibrating membrane 16 and the piezoelectric element 10 are laminated. The third slit portion 2d extends from the center of the vibrating membrane 16 toward the center position of the planar portion 17a. The third slit portion 2d is not provided on all of the four planar portions 17a, and in the example shown in Fig. 7, it is provided only on two planar portions 17a that face each other.

In this way, the vibrating body, in which the vibrating membrane 16 and the piezoelectric element 10 are laminated, is divided into six vibration regions by the main slit portion 2a and the third slit portion 2d. Specifically, the six vibration regions include a first vibration region 101 located between a pair of main slit portions 2a, and a second vibration region 102 located between the main slit portion 2a and the third slit portion 2d. The second vibration region 102 is divided into a shape different from that of the first vibration region 101, specifically, into a triangular shape with a smaller angle on the tip side than the first vibration region 101.

With this configuration, the first vibration region 101 and the second vibration region 102 have different shapes, so the resonance frequencies of the vibration regions 101 and 102 are different. This makes it possible to obtain a wider range of output characteristics than when all vibration regions have the same shape.

In this embodiment, the multiple vibration regions are configured with two different shapes, but they may be configured with three or more different shapes. Also, all of the multiple vibration regions may have different shapes.

(Third modification)
A transducer 1 according to a third modification will be described with reference to FIGS. 8, 9A, and 9B. In this third modification, the transducer 1 includes a membrane protective layer 30 laminated on the piezoelectric element 10. This membrane protection layer 30 has a function of protecting the connecting portion between the vibrating membrane 16 and the inner peripheral surface. The film protection layer 30 is a thin film made of a soft elastic material, such as resin. The membrane protection layer 30 is provided with a predetermined width along the inner circumferential surface (the plane portion 17a and the corner portion 17b) of the membrane support portion 17 forming the cavity 18, and is provided with a predetermined width so as to cover the entire surface of the piezoelectric element 10. It may be provided.

If a large displacement is applied to the vibration membrane 16 or if an impact is applied to the membrane 15, cracks may occur at the connection between the vibration membrane 16 and the inner peripheral surface. However, according to this embodiment, the membrane protection layer 30 covers the connection, so the membrane 15 can be protected from damage.

In addition, since the membrane protection layer 30 protects the connection between the vibration membrane 16 and the inner peripheral surface, it is sufficient if the membrane protection layer 30 provides protection at least at the connection. Therefore, the membrane protection layer 30 may have a shape in which a portion of the membrane protection layer 30 is thinned out as it moves inward from the inner peripheral surface. For example, in the example shown in FIG. 9B, the membrane protection layer 30 has triangular slits continuously provided along the circumferential direction.

(Fourth Modification)
A transducer 1 according to a fourth modified example will be described with reference to Fig. 10 and Fig. 11A to Fig. 11C. In this fourth modified example, the transducer 1 includes a cover layer 40 laminated on the piezoelectric element 10. The cover layer 40 is provided so as to cover the entire area of the piezoelectric element 10, for example, but it is sufficient that the cover layer 40 is present in an area that covers at least the dividing slit 2. The cover layer 40 is a thin film made of a soft material, such as a resin, that expands and contracts in response to the displacement of the vibration membrane 16. In Fig. 11A, the cover layer 40 located on the dividing slit 2 is provided in a planar manner so as to cover the upper part of the dividing slit 2.

According to this configuration, since the dividing slit 2 is covered by the cover layer 40, movement of air from one side of the vibrating membrane 16 to the opposite side can be suppressed. This makes it possible to suppress the movement of air through the divided slits 2, thereby making it possible to vibrate the air efficiently. Further, since the cantilever-shaped tip portions are connected to each other, sudden displacement of the tip portions can be suppressed when a strong external impact is input. Thereby, damage such as breaking of the vibrating membrane 16 can be suppressed.

Here, as shown in FIG. 11B, a cover layer 40 may be provided along the vertical grooves of the dividing slits 2. In this configuration, when the vibrating membrane 16 is displaced, the cover layer 40 is peeled off from the vertical grooves of the dividing slits 2, thereby allowing the vibrating membrane 16 to be displaced. This cover layer 40 can be formed by forming the dividing slits 2 in a vibrating body in which the vibrating membrane 16 and the piezoelectric element 10 are laminated, and then depositing the cover layer 40 in a thin film shape. Further, as shown in FIG. 11B, the tip side of the vibration region 100 may be chamfered so that the thickness decreases toward the center of the vibration membrane 16.

(Fifth Modification)
A transducer 1 according to a fifth modified example will be described with reference to Fig. 12A to Fig. 12C. Fig. 12A shows the tip sides of a pair of vibration regions 100 facing each other. In this fifth modified example, each of the four vibration regions 100 is chamfered so that the thickness of the tip decreases toward the center of the vibrating membrane 16. In the example shown in Fig. 12A, the upper surface side of the tip of the vibration region 100 is chamfered.

When a pair of opposing vibration areas 100 are displaced from each other, the tips of the vibration areas 100 may collide with each other. Therefore, by chamfering the tip of the vibration region 100, a gap is created through which the tip can escape, so collisions can be suppressed. Thereby, damage to the vibrating membrane 16 can be suppressed.

The area to be chamfered is not limited to the upper surface side of the tip of the vibrating region 100, but may be both the upper surface side and the lower surface side of the tip (see FIG. 12B). The method of chamfering the tip may be a method of continuously chamfering from the upper surface to the lower surface (see FIG. 12C).

(Sixth Modification)
A transducer 1 according to a sixth modified example will be described with reference to Fig. 13. This sixth modified example is characterized by the shape of the tip of the vibration region 100.

In the sixth modified example, one of the four vibration regions 100 has a circular protrusion 100a at the tip thereof, which extends to the center of the vibration membrane 16. On the other hand, the remaining vibration region 100 has a notch 100b at the tip thereof, which is cut in an arc shape so as to surround the protrusion 100a.

The notch 100b is provided to match the shape of the protrusion 100a, so that it is possible to prevent the tips of the vibration region 100 from colliding with each other. This makes it possible to prevent damage to the vibration membrane 16. In addition, the presence of the protrusion 100a makes it possible to close the gap in the center of the vibration membrane 16. As a result, it is possible to prevent the movement of air from one side of the vibration membrane 16 to the other side, and the air can be effectively vibrated by the vibration membrane 16.

Although the first to sixth modifications have been described above, the first to sixth modifications can also be used in combination with the technical features shown in each modification.

Fourth Embodiment
The transducer 1 according to the fourth embodiment will be described below with reference to Fig. 14 to Fig. 16. The transducer 1 according to the fourth embodiment differs from the transducer 1 according to the first embodiment in the structure of the membrane support portion 17. Descriptions of contents that overlap with the first embodiment will be omitted, and the following description will focus on the differences.

In this embodiment, the corners 17b that form the cavity 18 are shaped according to the interior angles of a rectangle. That is, adjacent flat surfaces 17a are connected at 90° via the corners 17b. In this type of membrane support section 17, three small cavities 17c, which are hollow portions extending in the film thickness direction of the vibration membrane 16, are provided around the corners 17b. Each small cavity 17c is independent of the others, and is provided in a position that is not connected to the cavity 18.

The small cavity 17c extends from the lower surface side of the membrane support part 17 to the upper surface side, and is formed to a height (depth) that does not penetrate the membrane support part 17. When viewed in a plane parallel to the vibration membrane 16, the small cavity 17c has a circular or elliptical shape.

When the inner circumferential surface is polygonal, stress generated in the membrane body 15 is concentrated at the corners 17b. Therefore, in this embodiment, the stress concentrated on the corner 17b is alleviated by providing a small cavity 17c around the corner 17b. Further, even if a crack occurs in the corner portion 17b, the progress of the crack can be stopped by the existence of the small cavity 17c formed with a curved surface around the corner portion 17b. Thereby, it is possible to suppress the membrane support portion 17 from being significantly damaged.

As shown in Figures 17A and 17B, the small cavity 17c and the cavity 18 may be formed to be connected. In the example shown in Figure 17A, the small cavity 17c and the cavity 18 are directly connected, and in the example shown in Figure 17B, the small cavity 17c and the cavity 18 are connected via a slit-shaped connecting portion 17c1.

(Fifth embodiment)
The transducer 1 according to the fifth embodiment will be described below with reference to FIGS. 18 and 19. The transducer 1 according to the fifth embodiment differs from the transducer 1 according to the first embodiment in the structure of the membrane support section 17. Description of contents that overlap with those of the first embodiment will be omitted, and the following description will focus on the differences. Note that in FIG. 18, some of the electrode pads 11a and 12a are omitted.

In this embodiment, the membrane support 17 has an inner circumferential surface that forms a cavity 18 . The inner circumferential surface is composed of one curved surface portion 17d and has a circular shape. A groove portion 17e is formed on the upper surface side of the membrane support portion 17 and has a depth that does not penetrate through the groove portion 17e. The groove portion 17e is located outside the curved surface portion 17d and is formed to surround the curved surface portion 17d.

In addition, in order to protect the wiring connecting the electrodes 11 and 12 to the electrode pads 11a and 12a, grooves 17e are not formed at this wiring location. Instead, grooves 17e are provided on the outer periphery of the wiring at the wiring location, so that the grooves 17e are doubled.

According to such a configuration, a groove portion 17e is formed on the upper surface of the membrane support portion 17 so as to surround the periphery of the vibrating membrane 16. This allows the region of the membrane support portion 17 inside the groove portion 17e to be bent inward. As a result, in accordance with the displacement of the vibrating membrane 16, the region inside the groove portion 17e can be displaced inward, and as a result, the amount of deflection of the vibrating membrane 16 can be increased. Therefore, since the vibrating membrane 16 can be largely displaced, the air can be vibrated efficiently.

(Sixth embodiment)
The transducer 1 according to the sixth embodiment will be described below with reference to FIGS. 20 to 22. The transducer 1 according to the sixth embodiment differs from the transducer 1 according to the first embodiment in the structure of the dividing slit 2. Description of contents that overlap with those of the first embodiment will be omitted, and the following description will focus on the differences.

In this embodiment, the membrane support portion 17 has an inner peripheral surface that forms a cavity 18. The inner peripheral surface is composed of one curved surface portion 17d and has a circular shape. The transducer 1 also has a dividing slit 2 that divides the vibrating body, which is made up of a piezoelectric element 10 and a vibrating membrane 16 stacked together, into multiple vibration regions 100.

The divided slit 2 includes four main slit portions 2a extending from the center of the vibrating membrane 16 toward the curved surface portion 17d. The four main slits 2a are distributed in a radial shape, thereby dividing the vibrating body in which the piezoelectric element 10 and the vibrating membrane 16 are stacked into four vibrating regions 100. As shown in FIG. 22, the end of the main slit portion 2a on the curved surface portion 17d side is formed into a curved shape.

Further, as shown in FIG. 22, a slit protection layer 50 is provided at the end of the main slit portion 2a on the curved surface portion 17d side. The slit protection layer 50 has a size that is large enough to surround the end of the main slit portion 2a. The slit protection layer 50 is a thin film made of a soft material. Note that the slit protective layer 50 may be formed of the same material as either the electrodes 11, 12 or the piezoelectric film 13. In this case, since there is no need to prepare a unique material for the slit protection layer 50, it is possible to suppress the manufacturing process of the transducer 1 from becoming complicated.

If the end of the main slit portion 2a is formed with a right-angled corner, stress may be concentrated at the corner. However, according to this embodiment, the end portion of the main slit portion 2a is formed in a curved shape. Thereby, it is possible to suppress a situation in which stress is concentrated at a specific location at the end of the main slit portion 2a. Thereby, it is possible to suppress the occurrence of cracks from the ends of the main slit portion 2a.

Note that the end portion of the main slit portion 2a may have a shape other than a curved shape. For example, it may be a polygonal shape that is a combination of three or more straight lines. Also, shapes that are a combination of a curved shape and a polygonal shape, such as a combination of two or more curved lines and one or more straight lines, or a combination of one or more curved lines and two or more straight lines. You may.

In addition, in this embodiment, a slit protection layer 50 is disposed at the end of the main slit portion 2a. This slit protection layer 50 protects the end of the main slit portion 2a. This makes it possible to prevent cracks from occurring at the end of the main slit portion 2a.

Note that in the method shown in the fifth embodiment, the inner circumferential surface forming the cavity 18 is circular, but the inner circumferential surface may have a polygonal shape.

(Seventh embodiment)
The transducer 1 according to the seventh embodiment will be described below with reference to FIGS. 23 and 24. The transducer 1 according to the seventh embodiment differs from the transducer 1 according to the first embodiment in the operating structure of the vibrating membrane 16. Description of contents that overlap with those of the first embodiment will be omitted, and the following description will focus on the differences. Note that in FIG. 23, some of the electrode pads 11a and 12a are omitted.

In this embodiment, the membrane body 15 includes a cantilever-type vibrating membrane 16 and a membrane support section 17. The vibrating membrane 16 has a substantially rectangular shape when viewed from a plane parallel to the vibrating membrane 16. The membrane support portion 17 surrounds the vibrating membrane 16 and is connected to one side of the vibrating membrane 16 . A gap 19 is set between the remaining three sides of the vibrating membrane 16 and the membrane support section 17. That is, the vibrating membrane 16 is supported in a cantilever shape.

The piezoelectric element 10 is not provided on the free end side of the vibration membrane 16, but is arranged on the base end side connected to the membrane support part 17. When a drive voltage is applied to each of the pair of electrodes 11, 12, a potential difference is generated between the pair of electrodes 11, 12. This potential difference displaces the free end side of the vibration membrane 16 in the film thickness direction. By repeatedly applying a drive voltage to the pair of electrodes 11, 12, the vibration membrane 16 alternately repeats displacement upward and downward. This vibration of the vibration membrane 16 causes the air around the vibration membrane 16 to vibrate, and the vibration of the air is output as sound waves.

One of the features of this embodiment is that screens 16b are provided on three sides of the vibrating membrane 16 separated from the membrane support part 17 by a gap 19. The screen 16b is provided on the surface opposite to the piezoelectric element 10 and extends toward the cavity 18. The screen 16b provided on the side located on the free end side is continuously formed along the side. On the other hand, the screens 16b provided on the two sides connecting the free end side and the base end side are provided intermittently at predetermined intervals (slits).

A space 17f is formed on the surface of the membrane support 17 that faces the free end of the vibration membrane 16. The space 17f is formed so as to leave the upper part of the membrane support 17.

When the free end of the diaphragm 16 warps, a gap is created in the thickness direction of the diaphragm 16. Air moves through this gap, which causes a large amount of air leakage when the air is vibrated. However, according to this embodiment, a partition 16b is provided on the underside of the diaphragm 16. This partition 16b prevents the formation of a gap, which prevents air from escaping.

Furthermore, screens 16b are formed intermittently on the sides where the vibrating membrane 16 is warped. Thereby, the screen 16b does not obstruct the displacement of the vibrating membrane 16. As a result, vibration of the vibrating membrane 16 can be tolerated.

In addition, by providing a space 17f in the membrane support part 17, it is possible to prevent interference between the partition 16b provided on the free end side and the membrane support part 17. This allows the vibration membrane 16 to be freely displaced. Also, because the space 17f is formed so as to leave the upper part of the membrane support part 17, it is possible to prevent the gap 19 between the vibration membrane 16 and the membrane support part 17 from becoming large. This makes it possible to suppress the flow of air through the gap 19.

The fourth to seventh embodiments have been described above, but the fourth to seventh embodiments can utilize the technical features shown in each embodiment in combination with each other. Further, the fourth to seventh embodiments can utilize a combination of the technical features shown in the first to third embodiments and the first to sixth modifications.

As described above, embodiments of the present invention have been described, but the statements and drawings that form part of this disclosure should not be understood as limiting the present invention. Various alternative embodiments, implementations, and operational techniques will be apparent to those skilled in the art from this disclosure.

For example, the transducer may be used not only for transmitting sound waves but also for receiving sound waves. In addition, the transducer may be applied to transmitting or receiving ultrasonic waves in addition to sound waves.

1 Transducer 2 Dividing slit 2a Main slit portion 2b Sub-slit portion 10 Piezoelectric element 11, 12 Electrode 13 Piezoelectric film 14 Piezoelectric slit 15 Film body 16 Vibration film 16b Partition 17 Film support portion 17a Planar portion 17b Corner portion 17c Small cavity 17d Curved surface portion 17e Groove portion 18 Cavity 19 Gap 20 Opening 30 Film body protection layer 40 Cover layer 50 Slit protection layer 100 Vibration region

Claims (10)

a membrane support portion having a cylindrical inner peripheral surface forming a hollow portion;
a vibrating membrane that is connected to the inner circumferential surface over the entire circumference of the inner circumferential surface and is displaceable in the film thickness direction;
a piezoelectric element comprising a pair of electrodes and a piezoelectric film sandwiched between the pair of electrodes, and laminated on the vibrating film;
a dividing slit passing through the vibrating body in which the vibrating membrane and the piezoelectric element are laminated in the thickness direction and dividing the vibrating membrane into a plurality of vibration regions;
The inner peripheral surface is
Since the hollow portion has a polygonal shape with chamfered corner portions of a prism, the cylindrical inner circumferential surface corresponds to a plurality of flat portions corresponding to the flat portions of the prism and the chamfered portions of the prism. and a corner portion that is
The dividing slit is
a main slit extending from the center of the vibrating membrane toward the corner;
a sub-slit portion extending from a connecting portion where the corner portion and the plane portion are connected to an end portion of the main slit portion on the corner side;
having a transducer. The piezoelectric element is
The transducer according to claim 1 , further comprising a piezoelectric slit penetrating the transducer in a thickness direction and extending from the planar portion to the dividing slit along a direction perpendicular to the planar portion. The transducer according to claim 1 or 2, wherein each of the pair of electrodes is connected to a circuit pattern for applying a drive voltage to the electrodes for each of the plurality of vibration regions. The piezoelectric element is
The transducer according to claim 1 , further comprising an opening penetrating the piezoelectric element in a thickness direction in a region corresponding to a center of the vibration membrane. The plurality of vibration regions include
A first vibration area;
The transducer according to claim 1 , further comprising: a second vibration region divided into a shape different from that of the first vibration region. The transducer according to claim 1 , further comprising a membrane protection layer provided on the piezoelectric element along the inner circumferential surface to protect a connection between the vibration membrane and the inner circumferential surface. The transducer according to any one of claims 1 to 6, further comprising a cover layer provided on the piezoelectric element so as to cover the dividing slit and expands and contracts according to displacement of the vibrating membrane. The transducer according to claim 1 , wherein each of the plurality of vibration regions is chamfered such that the thickness of a tip portion located on a center side of the vibration membrane decreases toward the center of the vibration membrane. A circular protrusion extending to the center of the vibrating membrane is provided at the tip of any one of the plurality of vibrating areas,
Out of the plurality of vibration regions, the remaining vibration regions excluding the vibration region provided with the protrusion are provided with a notch cut out in an arc shape so as to surround the protrusion. The transducer according to any one of claims 1 to 7. A membrane support portion having a cylindrical inner peripheral surface that forms a hollow portion;
a vibration membrane connected to the inner circumferential surface over the entire circumference thereof and displaceable in a thickness direction;
a piezoelectric element including a pair of electrodes and a piezoelectric film sandwiched between the pair of electrodes, the piezoelectric element being laminated on the vibration film;
a dividing slit penetrating a vibration body in a thickness direction, the dividing slit dividing the vibration body into a plurality of vibration regions,
The inner circumferential surface is
The hollow portion has a polygonal shape with the corners of a prism being chamfered, so that the cylindrical inner peripheral surface has a plurality of flat portions corresponding to the flat portions of the prism and corners corresponding to the chamfered portions of the prism,
The dividing slit is
extending from the center of the diaphragm toward the corner;
The piezoelectric element is
A transducer having a piezoelectric slit penetrating the piezoelectric element in a thickness direction and extending from the planar portion to the dividing slit along a direction perpendicular to the planar portion.

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