US3252035A

US3252035A - Electroluminescent lamp with built-in rearwardly-disposed input terminals

Info

Publication number: US3252035A
Application number: US260793A
Authority: US
Inventors: Jr Ivan E Buck
Original assignee: Westinghouse Electric Corp
Current assignee: Philips North America LLC
Priority date: 1963-02-25
Filing date: 1963-02-25
Publication date: 1966-05-17
Anticipated expiration: 1983-05-17

Description

May 17, 1966 l. E. BUCK. JR

ELEGTROLUMINESCENT LAMP WITH BUILT-IN REARWARDLY-DISPOSED INPUT TERMINALS Filed Feb. 25, 1963 FlG.3.

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INVENTOR. IVAN E. BUCK,JR.

W- .}LL)7iL- 3,252,035 ELECTROLUMINESCENT LAMP WITH BUILT-IN REARWARDLY-DISPOSED INPUT TERMINALS Ivan E. Buck, In, East Orange, N.J., as'signor to Westinghouse Electric Corporation, Pittsburgh, Pa., :1 corporation of Pennsylvania Filed Feb. 25, 1963, Ser. No. 260,793 6 Claims. (Cl. 313-108) This invention relates to electroluminescent devices and has particular reference to an electroluminescent lamp having an improved terminal structure.

One of the most troublesome problems encountered in the manufacture of electroluminescent lamps is that of making a durable electrical connection with the electrodes, especially the light-transmitting electrode on the face of the lamp. This is particularly true in the case of so-called metal-ceramic type lamps in which the phosphor particles are embedded in glass that has been fired onto a metal base member, which serves as one of the electrodes, and a transparent conductive coating is applied to the glass-phosphor layer to form the second electrode.

' It is desirable in most installations that both the electrode connections be made at the rear or opaque side of the lamp. In order to accomplish this, it was heretofore necessary to connect one of the lamp terminals to the light-transmitting electrode by means of an insulated lead that extended around the edge of the lamp. This fjumper type lead construction leaves much to be desired insofar as it requires that an opening be provided in the protective cover coat on the face of the lamp and thus exposes the electrical connection to attack by moisture or electrolysis. In addition, the lead wire insulation may break down in use resulting in a short circuit which would ruin the lamp. Moreover, since the connection is made with a portion of the lightemitting face of the lamp, this portion remains dark when the lamp is energized thus ,detracting from the appearance of the lamp and its performance.

It is accordingly the general object of the present invention to provide an improved terminal constructionfor an electroluminescent device that will avoid the aforementioned problems and disadvantages of the prior art.

Another object is the provision of an electroluminescent lamp having terminals that are simple and inexpensive to United States Patent make and which will not detract from either the performcoat and other strata of the cell structure through which 4 connection with both of the electrodes can be made. The light-emitting face is thus not marred by any dark regions when the lamp is energized and the protective coating remains intact over the entire face of the lamp.

In the case of a metal-ceramic type lamp, the rearwardly-extending edge or terminal segment is produced by using a rigid base member of the proper shape and Patented May 17, 1966 then forming the various layers on this member in the usual manner. In the case of an all-plastic lamp, the lamp may be constructed in the form of a fiat panel in the regular manner and then a preselected edge portion can be heat-softened and bent toward the back of the lamp to provide the rearwardly-extending terminal strip. This technique can also be used if the base member is made from an easily deformable metal such as aluminum and the various laminations constituting the electroluminescent cell are flexible enough to withstand the stresses produced by the bending operation.

A better understanding of the invention will be obtained from the accompanying drawing, wherein:

FIGURE 1 is a perspective View of a metal-ceramic type electroluminescent lamp embodying the present in vention; v

FIG. 2 is a similar view of the reverse side of the lamp showing the bent-over terminal strips and exposed contacts or portions thereof at the back of the lamp;

FIG. 3 is an enlarged cross-sectional view through the lamp along the reference line III-III of FIG. 1, in the direction of the arrows, a medial portion of the lamp being omitted to facilitate the illustration; and

FIGS. 4 to 8 are fragmentary side elevational views of alternative lamp embodiments illustrating other configurations that can be used in forming the terminal portions.

While the improved terminal construction of the present The invention In FIG. 1, there is shown atop perspective view of a metal-ceramic lamp 10 having a rectangular light-emitting face 12 and rearwardly-extending strips or edge portions A and B that comprise integral parts of the lamp and are bent back away from the light-emitting face into overlapping relationship with the back of the lamp. As shown in FIG. 2,

openings

22 and 24 are provided in the layers that comprise the cell structure and overlie the exposed faces of the strips through which each of the respective electrodes can be engaged.

The construction of the lamp 10 and the improved terminal means are illustrated in greater detail in the cross-sectional view shown in FIG. 3. As indicated, the lamp consists of the usual metal base electrode 14, such as an iron or aluminum plate for example, one side of which is covered with a fired-on glass-dielectric-phosphor layer 16. This composite layer is, in turn, coated with a radiation-transmitting electrode 18 such as a layer of tin oxide or the like. Protection against water vapor and other atmospheric contaminants is obtained by coating the light-transmitting electrode 18 with a cover coat 20 of suitable moisture-impervious material. In the metal-ceramic lamp here shown, theelectrolumines cent phosphor particles are embedded in a suitable glass and the protective coating 20 consists of a glass layer having a suitably low firing temperature.

As will be noted in FIG. 3, contrary to the conventional practice of using a flat plate as the base electrode, the base electrode in accordance with the present inven- 1 The aforementioned phosphor-dielectric layer 16, lighttransmitting electrode 18 and protective coating 20 are applied in the usual fashion so that they cover not only the flat body portion of the base electrode 14 but extend around the bent sides thereof and cover the exposed surfaces of the overlapped rearwardly-protruding edge or terminal portions A and B. The input terminals, accordingly, comprise anintegral part of the lamp rather than separate components as was the case heretofore.

As is illustrated in FIGS. 2 and 3, the phosphordielectric layer 16 and the protective coating 20 are removed from a preselected portion of the base electrode 14 to provide an opening 22 through which electrical connection with the base electrode can be made. A similar opening 24 is provided in the other edge portion B by removing the protective layer 20 to expose the underlying light-transmitting electrode 18. Thus, the lamp 19 can be energized without obstructing the lightemitting face 12 by connecting suitable lead conductors 26, as shown in FIG. 3, to the exposed parts of the base electrode 14 and light-transmitting electrode 18 located at the back of the lamp.

As is indicated in FIG. 3, additional protection from gaseous contaminants can be obtained by filling the cavity at the back of the lamp It] with a moisture-impervious material, such as glass or epoxy resin, and thus providing a protective backing 28 (shown in dotted outline} that extends across and seals off the back of the lamp, including the

terminal openings

22 and 24, from the atmosphere.

As will be obvious, the

openings

22 and 24 can be made by removing the overlying layers or by masking those portions of the bent-over edge portions A and B while the layers are being deposited.

Alternative embodiments Various other configurations can also be used to form the rearwardly-extending terminal or edge portions, as shown in FIGS. 4 to 8. In the lamp a shown in FIG. 4, the edge portion A is bent back sharply away from the light-emitting face 12d so that it seats against the body portion of the lamp. In FIG. 5, there is shown a lamp 10b in which the bend 30 is formed around a wire 32 that is tightly locked in and extends along the bead to provide a beaded edge thereat.

In FIG. 6, there is shown another lamp embodiment 100 wherein a bend 34 having a much larger radius of curvature is used so that only the end segment of the lapped edge portion A is seated against the back of the lamp This construction provides an enlarged bead and an eyelet-like opening 36 that extends along the lapped edge of the lamp.

In the lamp 10d shown in FIG. 7, a U-shaped bend 38 is employed so that the edge portion A overlies but is not seated against the fiat body portion of the lamp.

The lamp 10e shown in FIG. 8 is provided with an edge portion A that is joined to the body portion of the lamp by a right angle bend 40 and thus is disposed approximately normal to and rearwardly of the lighted face 12e of the lamp.

Electrical connection with the bent-over edge portions A in each of the above-described alternative embodiments is eifected by means of suitable contactors and conductors,

as indicated by the arrows in the respective figures.

It will be appreciated from the foregoing that the objects of the invention have been achieved insofar as a very simple and inexpensive terminal construction for electroluminescent devices has been provided which not only preserves the integrity of the protective coating but enables electrical connection with both of the electrodes to be conveniently effected at the back of the device without in any way interfering with or obscuring the light-emitting front face of the device.

While several embodiments have been illustratedand described, various changes in both the configuration and organization of parts can be made without departing from the spirit and scope of the invention.

I claim:

1. An electroluminescent lamp comprising, a metallic substantially flat base electrode having a bent edge portion that extends rearwardly and is disposed in overlapping relationship with the body portion of said base electrode,

a continuous phosphor-dielectric layer on the face of said base electrode opposite the bent-over edge portion thereof and extending around to and covering the outwardly disposed face of said edge portion, and

a second electrode comprising a continuous radiationtransmitting layer of electrically conductive material overlying said phosphor-dielectric layer,

said base electrode being accessible at the back of said lamp through an opening in portions of said phosphor-dielectric layer and said second electrode that cover the bent-over edge portion of said base electrode, whereby segments of both of said electrodes located behind the light-emitting face of said lamp are exposed for direct electrical connection and thus provide integral rearwardly-disposed input terminals for the lamp.

2. An electroluminescent lamp as set forth in claim 1 wherein,

said radiation-transmitting electrode is coated with a protective layer of radiation-transmitting material, and

access openings to the exposed part of the bent-over edge portion of said base electrode and a portion of said radiation-transmitting electrode are provided in said protective coating.

3. An electroluminescent lamp as set forth in claim 1 wherein a wire mandrel is locked in and extends along the bend joining the bent-over edge portion to the body portion of said base electrode and thus provides a protruding bead at said bend.

4. An electroluminescent lamp as set forth in claim 1 wherein the radius of the bend connecting the bent-over edge portion with the body portion of said base electrode is such that an enlarged bead and opening are defined by and extend along said bend.

5. An electroluminescent lamp as set forth in claim 1 wherein the said bent-over edge portion is spaced from the underlying body portion of said base electrode.

6. An electroluminescent device comprising;

a rigid base member having a rearwardly-extending portion that is disposed in overlapping relationship with the body portion of said base member,

the face of said base member opposite the rearwardlyextending portion being electrically conductive and comprising a first electrode that extends around to and covers the outwardly-disposed surface of said rearwardly-extending portion,

a continuous phosphor-dielectric layer overlying and covering said first electrode,

a second electrode comprising a continuous radiationtransmitting layer of electrically-conductive material that overlies and covers said phosphor-dielectric layer, and

a protective coating of radiation-transmitting material overlying said second electrode,

said first electrode being accessible through a first opening in portions of said phosphor-dielectric layer, second electrode and protective coating that cover the realrwardly-extending portion of said base member,

said second electrode being accessible through a second opening in another portion of said protective coating that overlies the rearwardly-extending portion of said base member,

whereby segments of'both electrodes carried by said 5 6 rearwardly-extending portion of the base member 2,900,545 8/ 1959 Rulon et a1 313-408 1 are exposed for direct electrical connection and thus 2,922,912 1/ 1960 Miller 313-408 provide integral input terminals located at the back 3,043,979 7/ 1962 Van Geel et a1 313-108 of said device. 3,153,166 10/ 1964 Thornton et a1 313-108 5 References Cited by the Examiner GEORGE N. WESTBY, Primary Examiner.

UNITED STATES PATENTS ROBERT SEGAL, Examiner.

2,714,683 8/1955 Jenkins 313-109 JUDD, Assistant Examiner-