Electroacoustic transduction film and manufacturing method of electroacoustic transduction film
Provided are an electroacoustic transduction film in which conversion between a vibration and a voltage is able to be appropriately performed without the occurrence of dielectric breakdown of the air between upper and lower thin film electrodes even when a high voltage is applied therebetween, a user is able to be prevented from coming into contact with a piezoelectric layer, and high productivity is achieved, and a manufacturing method of an electroacoustic transduction film. A piezoelectric layer which stretches and contracts in response to a state of an electric field, an upper thin film electrode formed on one principal surface of the piezoelectric layer, a lower thin film electrode formed on the other principal surface of the piezoelectric layer, an upper protective layer formed on the upper thin film electrode, and a lower protective layer formed on the lower thin film electrode are included, and a groove which penetrates the thin film electrode and the protective layer is formed in at least a portion of an outer peripheral portion in a surface direction of at least one of the upper thin film electrode and the upper protective layer, or the lower thin film electrode and the lower protective layer.
1. An electroacoustic transduction film, comprising:
a piezoelectric layer which stretches and contracts in response to a state of an electric field;
an upper thin film electrode formed on one principal surface of the piezoelectric layer;
a lower thin film electrode formed on the other principal surface of the piezoelectric layer;
an upper protective layer formed on the upper thin film electrode; and
a lower protective layer formed on the lower thin film electrode,
wherein a groove which penetrates the thin film electrode and the protective layer is formed in at least a portion of an outer peripheral portion in a surface direction of at least one of the upper thin film electrode and the upper protective layer, or the lower thin film electrode and the lower protective layer,
wherein the thin film electrode and the protective layer are divided by the groove into a thin film electrode and a protective layer on the inside of the groove, and a thin film electrode and a protective layer on the outside of the groove,
wherein the thin film electrode on the outside of the groove is a floating electrode which is electrically separated from the thin film electrode on the inside of the groove, and
wherein a width d2 of the groove is greater than or equal to a thickness d1 of the piezoelectric layer.
2. The electroacoustic transduction film according to claim 1 ,
wherein the groove is formed down to a portion of the piezoelectric layer.
3. The electroacoustic transduction film according to claim 1 ,
wherein the groove is formed along an entire periphery of the outer peripheral portion in the surface direction of at least one of the upper thin film electrode and the upper protective layer, or the lower thin film electrode and the lower protective layer.
4. The electroacoustic transduction film according to claim 2 ,
wherein the groove is formed along an entire periphery of the outer peripheral portion in the surface direction of at least one of the upper thin film electrode and the upper protective layer, or the lower thin film electrode and the lower protective layer.
5. The electroacoustic transduction film according to claim 1 ,
wherein a width d2 of the groove, a thickness d1 of the piezoelectric layer, and a voltage applied between the upper thin film electrode and the lower thin film electrode satisfy d2>V/3.5−d1.
6. The electroacoustic transduction film according to claim 3 ,
wherein a width d2 of the groove, a thickness d1 of the piezoelectric layer, and a voltage applied between the upper thin film electrode and the lower thin film electrode satisfy d2>V/3.5−d1.
7. The electroacoustic transduction film according to claim 4 ,
wherein a width d2 of the groove, a thickness d1 of the piezoelectric layer, and a voltage V applied between the upper thin film electrode and the lower thin film electrode satisfy d2>V/3.5−d1.
8. The electroacoustic transduction film according to claim 1 ,
wherein a thickness d1 of the piezoelectric layer is 5 to 100 μm.
9. The electroacoustic transduction film according to claim 7 ,
wherein a thickness d1 of the piezoelectric layer is 5 to 100 μm.
10. The electroacoustic transduction film according to claim 1 , further comprising:
an insulating filling portion which fills the groove.
11. The electroacoustic transduction film according to claim 9 , further comprising:
an insulating filling portion which fills the groove.
12. The electroacoustic transduction film according to claim 1 ,
wherein the piezoelectric layer is 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.
13. The electroacoustic transduction film according to claim 11 ,
wherein the piezoelectric layer is 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.
14. The electroacoustic transduction film according to claim 12 ,
wherein a local maximum value at which a loss tangent Tan δ at a frequency of 1 Hz becomes greater than or equal to 0.5 due to measurement of a dynamic viscoelasticity of the polymer material is present in a temperature range of 0° C. to 50° C.
15. The electroacoustic transduction film according to claim 13 ,
wherein a local maximum value at which a loss tangent Tan δ at a frequency of 1 Hz becomes greater than or equal to 0.5 due to measurement of a dynamic viscoelasticity of the polymer material is present in a temperature range of 0° C. to 50° C.
16. The electroacoustic transduction film according to claim 12 ,
wherein the polymer material has a cyanoethyl group.
17. The electroacoustic transduction film according to claim 15 ,
wherein the polymer material has a cyanoethyl group.
18. The electroacoustic transduction film according to claim 12 ,
wherein the polymer material is cyanoethylated polyvinyl alcohol.
19. The electroacoustic transduction film according to claim 17 ,
wherein the polymer material is cyanoethylated polyvinyl alcohol.
20. The electroacoustic transduction film according to claim 1 ,
wherein an electrode lead-out portion to which a voltage for driving the electroacoustic transduction film is applied is provided in the thin film electrode on the inside of the groove.