Thin film electroluminescent element

• US 4,547,703 A
• Filed: 01/26/1984
• Issued: 10/15/1985
• Est. Priority Date: 05/28/1982
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Abe, Atsushi, Matsuoka, Tomizo, Tohda, Takao, Fujita, Yosuke, Nitta, Tsuneharu
• Primary Examiner(s): Lesmes, George F.
• Assistant Examiner(s): Swisher, Nancy A. B.
• Application Number:
  US06/576,394
• Time in Patent Office: 628 Days
• Field of Search: 428/690, 428/691, 428/917, 250/327.2, 313/509
• US Class Current: 313/509
• CPC Class Codes: H01B 3/12 ceramics
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

In a thin film electroluminescent element comprising a phosphor thin film, a dielectric thin film disposed on at least one of the surfaces of the phosphor thin film and electrodes for applying a voltage across the thin films, the aforementioned dielectric thin film is formed of a dielectric material expressed by a general formula of AB₂ O₆ (where A represents a divalent metal element and B represents a pentavalent metal element). By employing the dielectric material, the voltage for driving a thin film electroluminescent element can be lowered without decreasing the brightness of the element. Further, by using a composite dielectric thin film in which the dielectric thin film expressed by the aforementioned general formula AB₂ O₆ is laminated with a dielectric thin film which is not susceptible to dielectric breakdown of self-healing type, the composite dielectric thin film is made susceptible to the dielectric breakdown of self-healing type. Additionally, the value of product of the dielectric breakdown field intensity and dielectric constant is increased to obtain a thin film electroluminescent element having excellent characteristics.

Claims

1. A thin film electroluminescent element comprising a phosphor thin film, a dielectric thin film disposed on at least one surface of said phosphor thin film, and electrodes for applying a voltage across said films, wherein said dielectric thin film comprises a dielectric material subject to dielectric breakdown of the self-healing type having a composition expressed by the general formula of AB₂ O₆, where A is at least one divalent metal element selected from the group consisting of Pb, Sn, Mg, Ca, Sr, Ba, Zn and Cd, and B is at least one pentavalent metal element selected from the group consisting of Ta and Nb, wherein the product E_b ·

ε

.sub.γ

of the dielectric breakdown electric field intensity E_b and dielectric constant ε

.sub.γ

for the dielectric thin film is greater than or equal to 80×

10⁶ V/cm.

2. A thin film electroluminescent element according to claim 1, wherein the divalent metal element A is at least one selected from a group consisting of Pb, Sr and Ba.

3. A thin film electroluminescent element according to claim 1, wherein the divalent metal element A is Pb.

4. A thin film electroluminescent element comprising a phosphor thin film, a dielectric thin film disposed on at least one surface of said phosphor thin film, and electrodes for applying a voltage across said films, wherein said dielectric thin film comprises a dielectric material having a composition expressed by the general formula of AB₂ O₆, wherein A is at least one divalent metal selected from a group consisting of Pb, Sn, Mg, Ca, Sr, Ba, Zn and Cd, and B is at least one pentavalent metal selected from the group consisting of Ta and Nb.

5. A thin film electroluminescent element according to claim 4, wherein the divalent metal element A is at least one selected from a group consisting of Pb, Sr and Ba.

6. A thin film electroluminescent element according to claim 5, wherein the divalent metal element is Pb.

9. A thin film electroluminescent element according to claim 4, wherein the divalent metal element A is at least one selected from a group consisting of Pb, Sr and Ba.

10. A thin film electroluminescent element according to claim 9, wherein the divalent metal element is Pb.

7. A thin film electroluminescent element comprising a phosphor thin film, a dielectric thin film disposed on at least one surface of said phosphor thin film, and electrodes for applying a voltage across said films, wherein the dielectric thin film comprises a first dielectric thin film layer which is subject to dielectric breakdown of the self-healing type, expressed by the general formula of AB₂ O₆ where A represents a divalent metal element selected from the group consisting of Pb, Sn, Mg, Ca, Sr, Ba, Zn and Cd, and B represents a pentavalent metal element selected from the group consisting of Ta and Nb, and a second dielectric thin film layer superimposed thereon, wherein said second dielectric thin film has a product E_b ·

ε

.sub.γ

of dielectric breakdown electric field intensity E_b and dielectric constant ε

.sub.γ

not smaller than 80×

10⁶ V/cm and is not susceptible to a dielectric breakdown of the self-healing type.

8. A thin film electroluminescent element according to claim 7, wherein the second dielectric thin film, not susceptible to the dielectric breakdown of the self-healing type, is formed from a dielectric material containing perovskite type titanate as a main component.

11. A thin film electroluminescent element according to claim 7, wherein the divalent metal element A is at least one selected from a group consisting of Pb, Sr and Ba.