Method of making electroluminescent lamp

• US 6,626,723 B2
• Filed: 08/09/2002
• Issued: 09/30/2003
• Est. Priority Date: 04/14/1999
• Status: Expired due to Fees

• Current Assignee: Seiko Precision Incorporated (Seiko Group)
• Original Assignee: Seiko Precision Incorporated (Seiko Group)
• Inventors: Yoneda, Koji
• Primary Examiner(s): Ramsey, Kenneth J.
• Assistant Examiner(s): Santiago, Mariceli
• Application Number:
  US10/215,786
• Publication Number:
  US 20030006700A1
• Time in Patent Office: 417 Days
• Field of Search: 445/24, 445/25, 427/66, 313/504, 313/509, 313/506, 428/690, 428/917
• US Class Current: 445/24
• CPC Class Codes: H05B 33/12 Light sources with substantially two-dimensional radiating surfaces
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers

Abstract

The difference of luminance between a front surface side and a rear surface side as viewed from the front surface side is reduced in a multi-layered EL lamp. An EL lamp includes a first laminate formed by serially laminating a first transparent electrode, a first luminescent layer and a first insulating layer, a second laminate formed by serially laminating a second transparent electrode, a second luminescent layer and a second insulating layer on the first laminate, and a rear electrode formed on the second laminate, wherein a dielectric constant between the first and second transparent electrodes is set to a value smaller than a dielectric constant between the second transparent electrode and the rear electrode. This can be achieved by limiting the amount of a high dielectric material to be mixed in the first insulating layer to not greater than 90% in terms of a weight ratio of a high dielectric material mixed in the second insulating layer, or by increasing the thickness of the first luminescent layer to 130 to 250% of the thickness of the second luminescent layer. After the adjustment is made in this way, the thickness of the first insulating layer may be set to not greater than 90% of the thickness of the second insulating layer or may be omitted.

Claims

1. A method of making an EL lamp comprising:

serially laminating a first transparent electrode, and a first luminescent layer to form a first laminate;

serially laminating a second transparent electrode, a second luminescent layer and an insulating layer on said first laminate to form a second laminate; and

forming a rear electrode on said laminate;

wherein a dielectric constant between said first transparent electrode and said second transparent electrode is set to a value smaller than a dielectric constant between said second transparent electrode and said rear electrode.

2. A method of making an EL lamp according to claim 1, further comprising forming said first laminate by serially laminating an insulating layer;

a high dielectric material in said insulating layer having a lower weight ratio than a high dielectric material in said insulating layer of said second laminate.

3. A method of making an EL lamp according to claim 1, wherein the thickness of said first luminescent layer is greater than the thickness of said second luminescent layer.

4. A method of making an EL lamp according to claim 2, wherein a high dielectric material is mixed into said insulating layer of said laminate which is not greater than 90% in terms of a weight ratio to a high dielectric material which is mixed into said second insulating layer.

5. A method of making an EL lamp according to claim 3, wherein said first luminescent layer is formed with luminescent bodies concentrated in a lower portion.

6. A method of making an EL lamp according to claim 1, wherein the thickness of said first luminescent layer is 130 to 250% of the thickness of said second luminescent layer.

7. A method of making an EL lamp according claim 2, wherein the thickness of said first luminescent layer is greater than the thickness of said luminescent layer of said second laminate.

8. A method of making an EL lamp according to claim 1, further comprising forming said first laminate by serially laminating an insulating layer;

the thickness of the insulating layer of said first laminate formed to be less than the thickness of said insulating layer of said second laminate.

9. A method of making an EL lamp according to claim 2, wherein the thickness of the insulating layer of said first laminate formed to be less than the thickness of said insulating layer of said second laminate.

10. A method of making an EL lamp according to claim 8, wherein the thickness of said insulating layer of said first laminate is not greater than 90% of the thickness of said insulating layer of said second laminate.

11. A method of making an EL lamp according to claim 3, wherein the step of forming said first luminescent layer is comprised of forming a layer of a luminescent ink having luminescent bodies in a resin binder and forming a layer of resin binder.

12. An EL lamp according to claim 11, wherein the layer of resin binder is an insulating layer.

13. A method of making an EL lamp according to claim 2, wherein the weight ratio of said high dielectric material in said insulting layer of said first laminate is essentially zero.