Thin-film electroluminescence apparatus including optical interference filter

• US 4,995,043 A
• Filed: 01/29/1990
• Issued: 02/19/1991
• Est. Priority Date: 03/24/1989
• 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, Kuwata, Jun
• Primary Examiner(s): Scott, Jr., Leon
• Application Number:
  US07/471,967
• Time in Patent Office: 386 Days
• Field of Search: 378/45, 378/7, 372/39, 313/112, 313/503, 313/509
• US Class Current: 372/7
• 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: H05B 33/24 of metallic reflective layers H05B33/26 takes precedence

Abstract

An electroluminescence apparatus in which voltage is applied to a lamination of a fluorescent material layer and a dielectric layer through a pair of electrodes one of which is light-transmissible to extract fluorescence. A reflecting mirror layer is provided on the lamination while a particular relationship is established between the refractive index and the thickness of the lamination, thereby improving the efficiency with which the fluorescence is extracted.

Claims

1. A thin-film electroluminescence apparatus comprising:

a pair of electrode layers at least one of which is light-transmissible;

a fluorescent material layer or a laminated structure of a fluorescent material layer and a dielectric material layer, a voltage being applied to said fluorescent material layer or said laminated structure through said pair of electrode layers; and

reflecting mirror layers provided on two sides of said fluorescent material layers or said laminated structure of fluorescent and dielectric material layers, said reflecting mirror layers having a reflectivity equal to or larger than 0.7 and smaller than 1 with respect to a wavelength λ

of light emitted from said fluorescent material layer;

wherein the following relationship is established between the refractive index n of said fluorescent material layer or said laminated structure of fluorescent and dielectric material layers;

space="preserve" listing-type="equation">d=K·

n.sup.-1 ·

λ

/2

where K is a positive integer equal to or larger than 1 and where d is the total thickness of said fluorescent material layer or said laminated structure.

2. A thin-film electroluminescence apparatus according to claim 1, wherein said electrode layer has a reflectivity which is substantially the same as that of said reflecting mirror layers.

3. A thin-film electroluminescence apparatus including an optical interference filter, comprising:

a light-transmissible electrode layer;

a light reflecting electrode layer;

a fluorescent material layer or a laminated structure of a fluorescent material layer and a dielectric material layer, a voltage being applied to said fluorescent material layer or said laminated structure through said electrode layers; and

a multilayer-film optical interference filter means for selectively transmitting light emitted from said fluorescent material layer and having an arbitrary wavelength λ

, said optical interference filter means being provided on a light extraction side of said fluorescent material layer or said laminated structure of fluorescent and dielectric material layers, said optical interference filter means being formed of at least one first dielectric film having a smaller refractive index and at least one second dielectric film having a larger refractive index, said first and second dielectric films being alternately laminated based on an equation λ

/4=film thickness x refractive index in the order of said second dielectric film and said first dielectric film, said fluorescent material layer having a refractive index larger than that of said first dielectric film based on an equation λ

/2·

N=film thickness x refractive index (where N is an integer equal to or larger than

     1), and further successively laminating a third dielectric film based on an equation λ

/4 x positive integer being laminated=film thickness x refractive index.

4. A thin-film electroluminescence apparatus according to claim 3, wherein an oxide having a refractive index of 2 or larger in a visible region and including a perovskite-type oxide or tantalum and an oxide or nitride having a refractive index larger than 1 and smaller than 2 are used for said dielectric material layers.

5. A thin-film electroluminescence apparatus comprising:

a pair of electrode layers at least one of which is light-transmissible;

a fluorescent material layer or a laminated structure of a fluorescent material layer and a dielectric material layer, a voltage being applied to said fluorescent material layer or said laminated structure through said pair of electrode layers; and

a multilayer-film optical interference filter means for selectively transmitting light emitted from said fluorescent material layer and having an arbitrary wavelength, said optical interference means being provided on a light extraction side of said fluorescent material layer or said laminated structure of fluorescent and dielectric material layers.

6. A thin-film electroluminescence apparatus comprising:

a pair of electrode layers at least one of which is light-transmissible; and

a fluorescent material layer or a laminated structure of a fluorescent material layer and a dielectric material layer, a voltage being applied to said fluorescent material layer or said laminated structure through said pair of electrode layers, said fluorescent material layer and said laminated structure of fluorescent and dielectric material layers constituting a multilayer-film optical interference filter means for selectively transmitting light emitted from said fluorescent material layer and having an arbitrary wavelength.

7. A thin-film electroluminescence apparatus comprising:

a pair of light-transmissible electrode layers;

a fluorescent material layer or a laminated structure of a fluorescent material layer and a dielectric material layer, a voltage being applied to said fluorescent material layer or said laminated structure through said pair of electrode layers; and

two types of multilayer-film optical interference filters provided on two light extraction sides of said fluorescent material layer or said laminated structure of fluorescent and dielectric material layers, said multilayer-film optical interference filters allowing transmission of light of different wavelengths emitted from said fluorescent material layer.