Transducer and electronic device

Patent metadata

Field	Value
Publication number	US-12598428-B2
Application number	US-202318536551-A
Country	US
Kind code	B2
Filing date	Dec 12, 2023
Priority date	Jun 18, 2021
Publication date	Apr 7, 2026
Grant date	Apr 7, 2026

Abstract

A transducer includes: a film support portion; a vibration film that is connected to the film support portion and capable of displacing in a thickness direction; a base material having an opposed surface that is opposed to the vibration film; and a first piezoelectric element that is provided with a pair of electrodes and a piezoelectric film sandwiched between the pair of electrodes, and is arranged on the vibration film, in which the transducer maintains a pressure in a space between the base material and the vibration film so as to keep displacement of the vibration film within a certain range.

First claim

The invention claimed is:

1 . A transducer comprising:
a film support portion; a vibration film that is connected to the film support portion and capable of displacing in a thickness direction; a base material having an opposed surface that is opposed to the vibration film to have a space formed therebetween, the opposed surface having an opening therein, the opening penetrating the base material to be in communication with the space, a width of the opening being smaller than a width of the film support portion; and a first piezoelectric element that is provided with a pair of electrodes and a piezoelectric film sandwiched between the pair of electrodes, and is arranged on the vibration film, wherein the transducer maintains a pressure in the space so as to keep displacement of the vibration film within a certain range.

2 . The transducer according to claim 1 , wherein
the vibration film has a main surface that faces the space; and an area of the opening in the opposed surface is 5% or less than an area of an entire region of the main surface of the vibration film.

3 . The transducer according to claim 1 , wherein
an area of the opening in the opposed surface is 0.9 mm 2 or less.

4 . The transducer according to claim 2 , wherein
the base material further has a main surface thereof on an opposite side of the opposed surface, and the base material further includes an opening member that surrounds the opening on the main surface thereof.

5 . The transducer according to claim 4 , wherein
the opening member has a main surface thereof, the main surface of the opening member and the main surface of the base material being on opposite sides of the opening member, and in a normal direction of the opposed surface, a distance between the opposed surface and the main surface of the opening member is longer than a diameter of a circle that has a same area as the area of the opening in the opposed surface.

6 . The transducer according to claim 4 , wherein
the opening member expands and contracts due to a change of air pressure in the space.

7 . The transducer according to claim 4 , wherein
the opening member is made of resin.

8 . The transducer according to claim 4 , wherein
the opening member is integrally formed with the base material.

9 . The transducer according to claim 2 , wherein
the base material further includes a protrusion-like opening valve that is connected to a side wall surface of the opening in a normal direction of the opposed surface, and the area of the opening in the opposed surface is changeable by the opening valve.

10 . The transducer according to claim 9 , further including a second piezoelectric element on the opening valve, wherein
the second piezoelectric element has a function of changing the area of the opening in the opposed surface by deforming the opening valve.

11 . The transducer according to claim 1 , wherein
an entire region of the opposed surface overlaps the vibration film in a normal direction of the opposed surface, and a volume of the space is a product of 1.1 times a projected area of the vibration film and 1 to 100 times an amount of displacement by which the vibration film is displaced in the film thickness direction.

12 . The transducer according to claim 11 , wherein
a volume of the space is changed by displacement of the base material.

13 . The transducer according to claim 11 , further including a third piezoelectric element on the base material and in the space, wherein
the third piezoelectric element has a function of changing a volume of the space by deforming the base material.

14 . The transducer according to claim 1 , wherein
the base material expands and contracts due to a change of air pressure in the space.

15 . The transducer according to claim 1 , wherein
the base material is made of resin.

16 . An electronic device comprising the transducer according to claim 1 .

Assignees

• Rohm Co Ltd

Inventors

• Naiki Takashi
• Shimoji Noriyuki
• Date Tomohiro
• GOUDA Kenji
• Amamoto Yurina

Classifications

• H04R1/2811

  for loudspeaker transducers · CPC title

• B81B2201/032

  Bimorph and unimorph actuators, e.g. piezo and thermo · CPC title

• B81B7/0061

  suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound · CPC title

• B81B2201/0271

  Resonators; ultrasonic resonators · CPC title

• H10N30/30

  with mechanical input and electrical output, e.g. functioning as generators or sensors · CPC title