Electroluminescent lamp with novel edge isolation

• US 5,332,946 A
• Filed: 06/24/1992
• Issued: 07/26/1994
• Est. Priority Date: 06/24/1991
• Status: Expired due to Term

• Current Assignee: World Properties Incorporated
• Original Assignee: Durel Corporation (Rogers Communications Inc.)
• Inventors: Eckersley, Rodney T., McGuigan, Ralph, Hooke, Will M., Stocker, Sharlyn R.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): PATEL, NIMESHKUMAR D
• Application Number:
  US07/903,600
• Time in Patent Office: 762 Days
• Field of Search: 313/506, 313/509, 313/511, 313/512, 313/496, 428/690
• US Class Current: 313/506
• CPC Class Codes: H05B 33/10 Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
• CPC Class Codes: H05B 33/12 Light sources with substantially two-dimensional radiating surfaces
• CPC Class Codes: H10K 71/851 Division of substrate

Abstract

An electroluminescent sheet-form lamp with a main portion of a conductive layer isolated from an edge region susceptible to detrimental conductive pathways by isolation provided along at least a portion of the perimeter of the lamp as a result of removal of a preapplied conductive coating such that, at the region of the isolation, the main portion of the one conductive layer which forms the respective electrode commences at a line spaced inwardly from the outer edge of the lamp. The preapplied conductive coating material may be removed to form a line of interruption that leaves in place a narrow margin of conductive coating in the edge region which is electrically isolated from the main portion of the coating forming the first electrode. The lamp may be formed by exposing preselected portions of the preapplied conductive coating to laser radiation sufficient to remove the preselected portions and form the region of isolation. A scribing technique or a mask, which may be a printed functional layer of the lamp, are employed.

Claims

1. In an electroluminescent sheet-form lamp comprising a transparent insulation layer, a transparent first conductive layer below said transparent insulation layer forming a first electrode, a layer of phosphor material below said transparent first conductive layer, a layer of dielectric material below said phosphor layer, a second conductive layer below said dielectric layer forming a second electrode, and electrical connection means for applying an electrical potential between the conductive layers to cause the phosphor to transmit light through the transparent first conductive layer and said transparent insulation layer, one of said conductive layers having been formed as a general conductive coating preapplied over a panel of larger dimension than said lamp, from which said lamp has been cut,

there being an edge region of said lamp susceptible to formation of a detrimental, electrically conductive path,

the improvement wherein a main portion of said one of said conductive layers is isolated from the susceptible edge region by isolation provided along at least a portion of the perimeter of the lamp as a result of removal of said preapplied general conductive coating such that, at the region of said isolation, said main portion of said one of said conductive layers which forms the respective electrode commences at a line spaced inwardly from the outer edge of said lamp,

said electrical connection for said one of said conductive layers being made to said main portion of said one of said conductive layers and being electrically isolated from said susceptible edge region, whereby a lamp formed by cutting its outline from said panel of larger dimension provides a lamp for which the formation of said conductive path in said edge region does not cause an adverse effect, and wherein

said preapplied general conductive coating has been removed to form a line of interruption that leaves in place a narrow margin of conductive coating in said edge region which is electrically isolated from the main portion of the coating forming the first electrode.

2. The electroluminescent lamp of claim 1

wherein said lamp is the product of the process of exposing preselected portions of said preapplied general conductive coating to laser radiation sufficient to remove said preselected portions and form said line of interruption,

making said electrical connection for said one conductive layer to said main portion of said one conductive coating in a manner so that said electrical connection is electrically isolated from said susceptible edge region, and cutting said lamp from said panel of larger dimension to provide a lamp for which the formation of said conductive path in said edge region does not cause an adverse effect.

3. The electroluminescent lamp of claim 2 formed by the process further comprising providing said laser radiation in the form of a beam of greater dimension than said preselected portions of said preapplied general conductive layer, and

providing a mask between a source of said radiation and said preapplied general conductive layer, said mask having aperture regions for exposing only said preselected portions of said preapplied general conductive layer.

4. The electroluminescent lamp of claim 3 wherein said mask is a printed mask layer printed over said preapplied general conductive coating to expose only said preselected portions to be removed.

5. The electroluminescent lamp of claim 4 formed by the process further comprising selecting a laser that removes said preapplied general conductive coating without removing all of said printed mask layer, said printed mask layer adapted to serve as a functional layer of said lamp.

6. The electroluminescent lamp of claim 4 formed by the process further comprising selecting a laser that removes at least part of said printed mask layer along with said preapplied general conductive coating.

7. The lamp of claim 6 formed by the process of preselecting the thickness of said mask layer relative to the thickness of said preapplied general conductive coating to remove only some of the thickness of said mask layer while forming said region of isolation by removing all of said preapplied general conductive coating in said preselected regions, the remaining portion of said printed mask layer adapted to serve as a functional layer of said lamp.

8. The electroluminescent lamp of claim 4, 5, 6 or 7 wherein said printed mask layer is a phosphor layer applied directly to said preapplied general conductive coating.

9. The electroluminescent lamp of claim 8 wherein said printed mask layer includes said phosphor layer and at least a portion of a layer forming said electrical connection to said preapplied general conductive coating.

10. The electroluminescent lamp of claim 8 wherein said laser radiation is provided by an excimer laser.

11. The electroluminescent lamp of claim 8 wherein said laser radiation is provided by a TEA laser.

12. The electroluminescent lamp of claim 3 wherein said mask is a separate member positioned above said preapplied general conductive coating.

13. The electroluminescent lamp of claim 12 wherein said laser radiation is provided by an excimer or TEA laser.

14. The electroluminescent lamp of claim 3 wherein said beam is of fan shape, with a cross-section of elongated form, and means are employed to produce relative motion of said preapplied general conductive coating and said beam in the direction transverse to the direction of elongation of said profile.

15. The electroluminescent lamp of claim 2 wherein said laser radiation is formed by a spot beam, wherein relative motion of said preapplied coating removes said preselected portions of said preapplied general coating.

16. The electroluminescent lamp of claim 14 or 15 wherein said laser radiation is provided by a CO₂ or TEA laser.

17. The electroluminescent lamp of claim 14 or 15 wherein said laser radiation is provided by an excimer laser.

18. The electroluminescent lamp of claim 1 wherein said one of said conductive layers is the transparent first conductive layer forming said first electrode.

19. The electroluminescent lamp of claim 1 wherein there is an insulating substrate below said second conductive coating and said one of said conductive layers is the second conductive layer forming said second electrode, preapplied to said insulating substrate.

20. The electroluminescent lamp of claim 1 wherein said phosphor material comprises encapsulated phosphor particles and said edge region is provided as a bare edge resulting from cutting of said lamp from said larger panel.

21. The electroluminescent lamp of claim 20 wherein said lamp is mounted in a manner that exposes said bare edge region to contact by a person, said isolation preventing a shock hazard to said person.

22. The electroluminescent lamp of claim 20 wherein said lamp is mounted in a manner that allows moisture to reach the bare edge region of the lamp, said isolation preventing electrical current leak through the moisture that could lead to degradation of the lamp structure.

24. The lamp of claim 1 or 23 wherein said line of interruption is formed by laser scribing said preapplied conductive layer.

25. The lamp of claim 1 or 23 wherein said transparent conductive layer comprises indium tin oxide.

26. The lamp of claim 1 or 23 wherein said phosphor material is doped zinc sulfide.

27. The lamp of claim 1 or 23 wherein said substrate layer is formed of polyester.

28. The lamp of claim 1 or 23 wherein an insulation layer is provided on the back of said second conductive layer.

23. In an electroluminescent sheet-form lamp comprising a transparent substrate layer, and, in successive relationship, a transparent first conductive layer forming a first electrode, a layer of phosphor material comprising encapsulated phosphor particles, a layer of dielectric material, a second conductive layer forming a second electrode, and electrical connection means for applying an electrical potential between the conductive layers to cause the phosphor to transmit light through the transparent conductive layer and said transparent substrate, said first transparent conductive layer comprising a preapplied continuous transparent coating over said substrate, outer edges of said layers defining said lamp being exposed to the ambient environment and being susceptible to formation of a detrimental conductive path,

the improvement wherein a line of interruption is provided along at least a portion of the perimeter of the lamp as a result of removal of a line of said preapplied transparent conductive coating, said line of interruption being spaced inwardly from the outer edges of said first transparent conductive layer,

said line of interruption electrically isolating a main, inner portion of said first transparent layer from a margin portion of said first transparent conductive layer adjacent to the edge of the lamp,

the electrical connection for said transparent conductive layer being connected to said main inner portion, said main portion serving as said first electrode and being electrically isolated from said margin portion of said first conductive layer,

whereby said isolation of said main portion provides a lamp for which the formation of said conductive path in said edge region does not cause an adverse effect.