Electroacoustic transduction film

Patent metadata

Field	Value
Publication number	US-9621997-B2
Application number	US-201514862380-A
Country	US
Kind code	B2
Filing date	Sep 23, 2015
Priority date	Apr 1, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

Disclosed is an electroacoustic transduction film suitable for a flexible speaker or the like, in which predetermined acoustic properties are able to be stably exhibited regardless of a bending state. The electroacoustic transduction film includes a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature, and electrode layers interposing the polymer composite piezoelectric body therebetween, and an area fraction of the piezoelectric body particles in a contact surface with respect to the electrode layer is less than or equal to 50%, and thus the object is attained.

First claim

What is claimed is:

1. An electroacoustic transduction film, comprising:
a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature; and
electrode layers disposed to interpose the polymer composite piezoelectric body therebetween,
wherein an area fraction of the piezoelectric body particles in a contact surface with respect to the electrode layer, which is calculated from data obtained by peeling off the electrode layer, by exposing the contact surface with respect to the electrode layer, and by imaging the contact surface with respect to the electrode layer, is less than or equal to 50%, and
wherein in a surface of the polymer composite piezoelectric body facing the electrode layer, at least one of an arithmetic average roughness Ra of less than or equal to 1 μm, a maximum valley depth Rv of less than or equal to 6 μm, and a maximum height roughness Rz of less than or equal to 12 μm is satisfied.

2. The electroacoustic transduction film according to claim 1 ,
wherein an adhesive layer is included between the polymer composite piezoelectric body and at least one electrode layer.

3. The electroacoustic transduction film according to claim 1 ,
wherein the polymer composite piezoelectric body is subjected to calender processing.

4. The electroacoustic transduction film according to claim 3 ,
wherein the polymer composite piezoelectric body is subjected to polarization processing after the calender processing.

5. The electroacoustic transduction film according to claim 1 ,
wherein the area fraction of the piezoelectric body particles in the contact surface with respect to the electrode layer is lower than a volume fraction of the piezoelectric body particles which is calculated from a sectional machining surface of the polymer composite piezoelectric body by using a focused ion beam.

6. The electroacoustic transduction film according to claim 1 ,
wherein a volume fraction of the piezoelectric body particles which is calculated from a sectional machining surface of the polymer composite piezoelectric body by using a focused ion beam is greater than or equal to 50%.

7. The electroacoustic transduction film according to claim 1 ,
wherein a protective layer is included on a surface of at least one of the electrode layers.

8. The electroacoustic transduction film according to claim 2 ,
wherein a thickness of the adhesive layer is less than or equal to 3 μm.

9. The electroacoustic transduction film according to claim 2 ,
wherein the adhesive layer is formed of a same material as the polymer material.

10. An electroacoustic transduction film, comprising:
a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature; and
electrode layers disposed to interpose the polymer composite piezoelectric body therebetween,
wherein an area fraction of the piezoelectric body particles in a contact surface with respect to the electrode layer, which is calculated from data obtained by peeling off the electrode layer, by exposing the contact surface with respect to the electrode layer, and by imaging the contact surface with respect to the electrode layer, is less than or equal to 50%, and
wherein the area fraction of the piezoelectric body particles in the contact surface with respect to the electrode layer is lower than a volume fraction of the piezoelectric body particles which is calculated from a sectional machining surface of the polymer composite piezoelectric body by using a focused ion beam.

11. The electroacoustic transduction film according to claim 10 ,
wherein an adhesive layer is included between the polymer composite piezoelectric body and at least one electrode layer.

12. The electroacoustic transduction film according to claim 10 ,
wherein the polymer composite piezoelectric body is subjected to calender processing.

13. The electroacoustic transduction film according to claim 12 ,
wherein the polymer composite piezoelectric body is subjected to polarization processing after the calender processing.

14. The electroacoustic transduction film according to claim 10 ,
wherein the volume fraction of the piezoelectric body particles which is calculated from the sectional machining surface of the polymer composite piezoelectric body by using the focused ion beam is greater than or equal to 50%.

15. The electroacoustic transduction film according to claim 10 ,
wherein a protective layer is included on a surface of at least one of the electrode layers.

16. An electroacoustic transduction film, comprising:
a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature; and
electrode layers disposed to interpose the polymer composite piezoelectric body therebetween,
wherein an area fraction of the piezoelectric body particles in a contact surface with respect to the electrode layer, which is calculated from data obtained by peeling off the electrode layer, by exposing the contact surface with respect to the electrode layer, and by imaging the contact surface with respect to the electrode layer, is less than or equal to 50%, and
wherein a volume fraction of the piezoelectric body particles which is calculated from a sectional machining surface of the polymer composite piezoelectric body by using a focused ion beam is greater than or equal to 50%.

17. The electroacoustic transduction film according to claim 16 ,
wherein an adhesive layer is included between the polymer composite piezoelectric body and at least one electrode layer.

18. The electroacoustic transduction film according to claim 16 ,
wherein the polymer composite piezoelectric body is subjected to calender processing.

19. The electroacoustic transduction film according to claim 18 ,
wherein the polymer composite piezoelectric body is subjected to polarization processing after the calender processing.

20. The electroacoustic transduction film according to claim 16 ,
wherein a protective layer is included on a surface of at least one of the electrode layers.

Assignees

• Fujifilm Corp

Inventors

• Miyoshi Tetsu
• Hatanaka Yusuke

Classifications

• H04R7/04

  Plane diaphragms · CPC title

• H04R17/005 Primary

  using a piezoelectric polymer · CPC title

• H04R17/00 Primary

  Piezoelectric transducers; Electrostrictive transducers (piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners {H10N30/00}) · CPC title

• H04R31/003

  for diaphragms or their outer suspension · CPC title

• H04R2499/11

  Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's · CPC title