Thin film electroluminescent element

• US 5,142,192 A
• Filed: 08/22/1991
• Issued: 08/25/1992
• Est. Priority Date: 09/20/1988
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited A Joint-Stock Company of Japan
• Original Assignee: Ricoh Company Limited
• Inventors: Kameyama, Kenji, Oseto, Seiichi, Takahashi, Masaetsu, Deguchi, Hiroshi, Kageyama, Yoshiyuki
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Horabik, Michael
• Application Number:
  US07/751,567
• Time in Patent Office: 369 Days
• Field of Search: 313/498, 313/503, 313/506, 313/509, 313/510, 313/512, 313/111, 313/116
• US Class Current: 313/506
• CPC Class Codes: H05B 33/12 Light sources with substantially two-dimensional radiating surfaces
• CPC Class Codes: H05B 33/26 characterised by the composition or arrangement of the conductive material used as an electrode

Abstract

A thin film electroluminescent element includes a luminous layer for emitting light by applying a voltage to the luminous layer through an electrode, the electrode being made of a metal; and a material for scattering the light and disposed on an end face of the luminous layer. A large picture polychromatic display apparatus includes a thin film electroluminescent element; and a material for scattering light and disposed in a luminous portion for emitting the light on an end face of the electroluminescent element, the light-scattering material forming a picture element. The display apparatus may include a thin film electroluminescent element formed by sequentially stacking a metallic electrode, an insulating layer and a luminous layer with each other on a glass substrate; and a material for scattering light and disposed on an end face of the element by scribing the element in the longitudinal direction thereof, the display apparatus being formed by combining a plurality of such elongated elements with each other, each of the elongated elements being provided with the light-scattering material. In the element, a plurality of luminous layers having different luminous wavelength characteristics are stacked with each other, and an insulating layer and a metallic electrode are disposed on both sides of the luminous layers. The light-scattering material mixes the lights emitted from the luminous layers with each other by the scattering of the lights and is disposed on the end faces of the luminous layers.

Claims

1. A thin film electroluminescent element comprising:

a luminous layer having two sides opposite to each other and an inner end face defining a central bore, said luminous layer adapted to emit light by applying a voltage between said two sides;

first electrode means disposed on said luminous layer at one side of said two sides for applying said voltage to said luminous layer, said first electrode means being adapted to reflect the light in the luminous layer to guide the light toward said inner end face;

second electrode means disposed on said luminous layer at the other side of said two sides for applying said voltage to said luminous layer, said second electrode means being adapted to reflect the light in the luminous layer to guide the light toward said inner end face, at least one of said first electrode means and second electrode means having a bore consistent with said bore of said luminous layer; and

central scattering means filled in said central bore of said luminous layer for scattering the light from the inner end face, so that the light from said inner end face is taken out perpendicularly with respect to said luminous layer.

2. A thin film electroluminescent element according to claim 1, wherein each of said first electrode means and said second electrode means comprises an insulating layer in contact with said luminous layer at one side thereof and a metal electrode disposed on said insulating layer at the other side of said insulating layer.

3. A thin film electroluminescent element according to claim 2, wherein said metal electrode of said first electrode is formed on a substrate.

4. A thin film electroluminescent element according to claim 3, wherein said second electrode means has said bore, and said scattering means is formed on said first electrode means.

5. A thin film electroluminescent element according to claim 4, wherein another luminous layer is disposed on said second electrode means through an insulating film, a third electrode means is disposed on said another luminous layer, and said scattering means extends to an end face of said another luminous layer.

6. A thin film electroluminescent element according to claim 5, wherein said luminous layer and said another luminous layer have luminous wavelength characteristics different from each other.

7. A thin film electroluminescent element according to claim 3, wherein said luminous layer has an outer end face, and said second electrode means surrounds said outer end face.

8. A thin film electroluminescent element according to claim 3, wherein each of said first electrode means and said second electrode means has said bore, said substrate is made of glass, and an upper face of said second electrode means and an upper face of said scattering means is covered with a black protecting layer.