Color thin film electroluminescent display

• US 5,445,899 A
• Filed: 05/17/1993
• Issued: 08/29/1995
• Est. Priority Date: 12/16/1992
• Status: Expired due to Fees

• Current Assignee: Siemens Rail Automation Ltd. (Siemens AG)
• Original Assignee: Siemens Rail Automation Ltd. (Siemens AG)
• Inventors: Schlam, Elliott, Budzilek, Russell A., Monarchie, Dominick L., Podoba, Myroslaw, Swatson, Richard R.
• Primary Examiner(s): Nold, Charles R.
• Application Number:
  US08/062,869
• Time in Patent Office: 834 Days
• Field of Search: 428/690, 428/691, 428/917, 313/505, 313/509, 313/506
• US Class Current: 428/690
• 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 33/28 of translucent electrodes
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

A multi-color TFEL display includes a low ohm metal assist structure in electrical contact with the transparent electrodes to improve display brightness, and a light absorbing dark layer to increase display contrast.

Claims

1. A sunlight viewable multi-color electroluminescent display panel, comprising:

a glass substrate;

a plurality of parallel transparent electrodes deposited on said glass substrate, each of said transparent electrodes having a metal assist structure formed on and in electrical contact over a portion of said transparent electrodes;

a first dielectric layer deposited on said plurality of transparent electrodes;

a layer of phosphor material deposited on said first dielectric layer having a preselected activator and a preselected co-activator implanted therein to provide color luminescent material;

a second dielectric layer deposited on said layer of phosphor material;

a layer of light absorbing dark material, deposited on said second dielectric layer for reducing reflected light; and

a plurality of metal electrodes each deposited in parallel over said layer of light absorbing dark material.

2. The sunlight viewable multi-color electroluminescent display panel of claim 1, wherein each of said metal assist structures comprises a first refractory metal layer, a primary conductor layer formed on the first refractory layer, and a second refractory metal layer formed on the primary conductor layer such that the first and second refractory metal layers are capable of protecting the primary conductor payer from oxidation when the electroluminescent display is annealed to activate said phosphor layer.

3. The sunlight viewable electroluminescent display panel of claim 2 wherein said metal assist structure covers about 10% or less of said transparent electrode.

4. The sunlight viewable electroluminescent display panel of claim 2 wherein said layer of light absorbing dark material is PrMnO₃.

5. The sunlight viewable electroluminescent display panel of claim 1 wherein said layer of light absorbing dark material has a resistivity of least 10⁸ ohms.cm.

6. The sunlight viewable electroluminescent display panel of claim 1 wherein said layer of light absorbing dark material is GeN.

7. The sunlight viewable electroluminescent display panel of claim 2 wherein the edges of said metal assist structure are chamfered.

8. The sunlight viewable electroluminescent display panel of claim 2, wherein said metal assist structure further comprises an adhesion layer formed between said first refractory metal layer and the transparent electrode, wherein said adhesion layer is capable of adhering to the transparent electrode and said first refractory metal layer.

9. A sunlight viewable multi-color electroluminescent display panel, comprising:

a glass substrate;

a plurality of parallel transparent electrodes deposited on said glass substrate, each of said transparent electrodes having a metal assist structure formed on and in electrical contact over a portion of said transparent electrodes;

a first dielectric layer deposited on said plurality of transparent electrodes;

a layer of phosphor material deposited on said first dielectric layer having a preselected activator and a preselected co-activator implanted therein to provide color luminescent material;

a layer of light absorbing dark material, deposited on said layer of phosphor material for reducing reflected light;

a second dielectric layer deposited on said layer of light absorbing dark material; and

a plurality of metal electrodes each deposited in parallel over said layer of light absorbing dark material.

10. The sunlight viewable electroluminescent display panel of claim 9 wherein the edges of said metal assist structure are chamfered.

11. The sunlight viewable electroluminescent display panel of claim 10 wherein said layer of light absorbing dark material has a dielectric constant of at least seven.

12. The sunlight viewable electroluminescent display panel of claim 11 wherein said metal assist structure covers about 10% or less of said transparent electrode.

13. The sunlight viewable electroluminescent display panel of claim 12 wherein said layer of light absorbing dark material is a graded layer of light absorbing dark material.

14. The sunlight viewable electroluminescent display panel of claim 13 wherein said graded layer of light absorbing dark material comprises a nonstoichoemetric silicon nitride, SiN_x.

15. A sunlight viewable multi-color electroluminescent display panel, comprising:

a glass substrate;

a plurality of parallel transparent electrodes deposited on said glass substrate, each of said transparent electrodes having a metal assist structure formed on and in electrical contact over a portion of said transparent electrodes;

a first dielectric layer deposited on said plurality of transparent electrodes;

a layer of phosphor material deposited on said first dielectric layer having a preselected activator and a preselected co-activator implanted therein to provide color luminescent material;

a second dielectric layer deposited on said layer of phosphor material; and

a plurality of metal electrodes each deposited in parallel over said second dielectric layer, each of said metal electrodes comprising a layer of light absorbing dark material between said second dielectric layer and the electrically conductive portion of said metal electrodes.

16. The sunlight viewable electroluminescent display panel of claim 15 wherein said layer of light absorbing dark material is a graded layer of light absorbing dark material.

17. The sunlight viewable electroluminescent display panel of claim 16 wherein said layer of light absorbing dark material has an absorption coefficient of about 10⁵ /cm.

18. The sunlight viewable electroluminescent display panel of claim 17 wherein said layer of light absorbing dark material is PrMnO₃.

19. The sunlight viewable electroluminescent display panel of claim 16 wherein said graded layer of light absorbing dark material comprises a nonstoichiometric silicon nitride, SiN_x.

20. The sunlight viewable electroluminescent display panel of claim 19 wherein said layer of light absorbing dark material is GeN.