US 3430088 A
Description (OCR text may contain errors)
Feb. 25, 1969 v, L, BEsw| 3,430,088
WIRE TERMINAL ELECTROLUMINESCENT DEVICE AND MANUFACTURE Filed Sept. 30, 1966 Invenflrov: \l'ewnon L. Beswick b .V H oT-neg United States Patent 6 Claims This invention relates in general to electroluminescent lamps or similar devices and more particularly to a terminal construction therefor and to the manufacture thereof.
In certain applications for electroluminescent devices, it is required that the device be provided with wire-type outer leads or terminals for connecting the device to an electrical power supply. To be satisfactory, such a terminal construction not only must be moisture-resistant in order to prevent moisture penetration into the device such as would cause depreciation in its light output, but it also must afford adequate electrical shock protection, be free from electrical loss, and must be capable of withstanding the vibrations and physical shocks normally encountered in service without loosening and breaking the circuit so as to render the device inoperative. In the case of electroluminescent devices of the type which are encapsulated in plastic, the problem of providing it with a wire terminal construction fulfilling all the above-mentioned requirements is a particularly difiicult one.
It is an object of the invention, therefore, to provide an electroluminescent device of the plastic-encapsulated type having a wire terminal construction of moisture-tight and vibration-resistant character, and which affords protection from electrical shock and is substantially free from electrical losses.
Another object of the invention is to provide an electroluminescent device of the plastic-encapsulated type having a wire terminal structure which is of simple but sturdy construction and is easy to fabricate.
Still another object of the invention is to provide a novel method of making an electroluminescent device with wire-type terminals protruding therefrom.
Briefly stated, in accordance with one aspect of the invention, the bared end portions of a pair of plastic covered wire leads molded in and protruding from a flanged plastic stud are laminated between the flanged end of the plastic stud and the outer side of one of the plastic encapsulating sheets of an electroluminescent device so as to be pressed into firm electrical contact with the outer end portions of respective ribbon-type conductors which are connected to the respective electrodes of the device and are threaded through respective apertures in the said plastic encapsulating sheet and laminated to the outer side thereof.
In accordance with a further aspect of the invention, the flanged end of the plastic stud completely overlies the conductor-receiving apertures in the plastic encapsulating sheet of the device as well as the bared ends of the wire leads and the outer end portions of the ribbon conductors in order to completely seal off the said apertures from the outside atmosphere, and to embed the interconnected portions of the wire leads and ribbon conductors, thereby additionally assuring the formation of a moisture-tight seal of the lead-in conductors into the device and affording protection against accidental electrical shock and electrical losses.
Further objects and advantages of the invention will appear from the following detailed description of species thereof and from the accompanying drawings.
In the drawings,
FIG. 1 is a perspective view of an electroluminescent 3,430,088 Patented Feb. 25, 1969 device provided with a wire terminal construction according to the invention.
FIG. 2 is a sectional view, on a greatly enlarged scale, taken on the line 22 of FIG. 1.
FIG. 3 is a fragmentary plan view of an electroluminescent device showing one of the steps in the formation thereof with a wire terminal construction according to the invention.
FIG. 4 is a fragmentary sectional view, on an enlarged scale, taken on the line 44 of FIG. 3.
FIG. 5 is a sectional view of the wire-carrying plastic stud component of the terminal structure according to the invention.
FIG. 6 is an elevation of the plastic stud component shown in FIG. 5 after the bending over of the wire leads thereof in readiness for its lamination to the electroluminescent device, and
FIG. 7 is a bottom plan view of a modified form of wire-terminated electroluminescent device according to the invention.
Referring to the drawing, the electroluminescent device 1 according to the invention comprises a conventional type flexible electrically active cell portion or assembly 2 (FIG. 4) sealed within a substantially moisture-impervious outer encapsulating envelope 3 comprised of sheets 4 and 5 of suitable thermoplastic material which flows under heat and pressure. The plastic sheets 4 and 5 overreach the marginal edges of the electrically active cell portion 2 and are sealed together along their margins so as to completely enclose the cell portion 2. The materials selected for the encapsulating envelope 3 are preferably tough and stable in addition to exhibiting light-transmitting qualities and high impermeability to moisture, and further they are preferably flexible in nature. Among the materials which may be satisfactorily employed for this purpose are polyethylene, polytetrafluoroethylene, polychlorotrifluoroethylene, polystyrene, methyl methacrylate, polyvinylidine chloride, polyvinyl chloride, polycarbonate materials such as, for example, the reaction products of diphenyl carbonate and Bisphenol A, and polyethylene terephthalate. The material preferably employed for such purpose, however, consists of polychlorotrifiuoroethylene film, such as that commercially known as Kel F or Aclar, of approximately 0.005 inch thickness.
The electrically active portion or assembly 2 of the electroluminescent device 1 may consist, in general, of any of the known types of flexible electroluminescent cell assemblies which are of non-fragile character and light in weight. Preferably, however, the electrically active portion or assembly 2 of the electroluminescent device 1, i.e., the light-producing components thereof, is of the general form disclosed and claimed in US. Patent 2,945,976, Fridrich et 211., dated July 19, 1960 and comprising a sheet of metal foil 6, for instance full-soft aluminum foil of around 2 mils thickness, coated with an insulating layer 7 of high dielectric constant material which is overcoated with a light-producing layer 8 of an electroluminescent phosphor dispersed in a dielectric material. The aluminum foil sheet '6 constitutes one of the conductive electrode layers of the device and is placed over the lowermost plastic sheet 5 of the encapsulating envelope 3 leaving a clear margin all around. The insulating layer 7 may consist of barium titanate dispersed in an organic polymeric matrix of high dielectric constant material such as cyanoethyl cellulose plasticized with cyanoethyl phthalate actric layer 3 is a thin light-transmitting electrically conductive layer 9 constituting the other conductive electrode layer of the electroluminescent device 1. The electrode layer 9 may be of any suitable type such as, for example, the electrically conductive glass paper described and claimed in Jaffe US. Patent 2,849,339, and having a thickness around 1 mil, or the electrically conductive lacquer described and claimed in copending US. application Ser. No. 556,837, Jaife et al., filed June 9, 1966, now Patent No. 3,315,111, and having a thickness around mils, for example. Overlying the light-transmitting electrode layers 9 is a layer of a suitable transparent thermoplastic material, preferably one having hydrophylic properties, i.e., having an atfinity for moisture. For such purpose, polyamide condensation products such as nylon 6,6 or nylon 6 such as that known as Caplene or Capran, have been found to be particularly effective as hydrophylic materials for the plastic layer 10.
The component layers 6 to 10 of the electroluminescent device 1 are laminated together, under heat and pressure, between the outer plastic encapsulating sheets 4 and 5. The electroluminescent device 1 may be of any configuration such as, for example, of square shape or, as shown, of rectangular shape, and the plastic outer sheets 4- and 5 overreach the marginal edges of the electrically active cell portion 2 and are sealed together along their abutting marginal edges so as to completely enclose and encapsulate the cell portion 2. The electroluminescent device may be energized by applying a suitable potential such as an alternating voltage, for example, 120 volts 60 cycles AC, to ribbon-type electrical conductors 11 and 12 (FIG. 3) which are laminated into the device in electrical contact with the respective electrode layers 6 and 9 and project laterally from the edge of the electrically active cell assembly 2 in parallel side-by-side relation where they are sealed between the sealed-together marginal edge portions of the plastic outer encapsulating sheets 4 and 5. The conductors 11 and 12 are preferably formed of relatively fine mesh wire cloth, for example, 200 to 300 mesh, of suitable electrically conductive material such as copper or Phosphor bronze, for instance.
In accordance with the invention, the electroluminescent device 1 is provided with a wire-type terminal construction 13 comprised, in general, of a pair of flexible plastic-coated wire leads 1'4 and 15 which are molded into a flanged plastic stud 16 which is laminated to the outer face of one or the other of the plastic encapsulating sheets 4, 5, preferably the bottom sheet 5 as shown, at a region thereof outwardly beyond the marginal edge of the cell portion 2 of the device. To this end, the plastic encapsulating envelope 3, in the case of the particular electroluminescent device 1 illustrated in FIGS. 1 to 4, is provided with a wing extension 17, constituted by corresponding individual wing extensions 18 and 19 projecting from the corresponding edges of the respective plastic encapsulating sheets 4, 5 and sealed together during the lamination of the device, to which wing extension 17 the flanged plastic stud 16 is laminated.
As shown in FIG. 4, the ribbon conductors 11, 12 from the electrodes 6 and 9 of the electroluminescent device extend in parallel side-by-side relation through the wing extension 19 of the bottom plastic encapsulating sheet 5 to the outer side or face 20 thereof so as to be exposed thereat for the purpose of permitting the electrical connection thereof to the wire leads 14, 15. To this end, the outer ends of the ribbon conductors 11, 12 are threaded through respective slots or apertures 21 in the wing extension 19 of the plastic encapsulating sheet 5, during the lay-up assembly of the component layer elements 4 to 10 of the device preparatory to the lamination together thereof, and the projecting outer ends 22, 23 of the conductors 11, 12 then bent to lie flat against the outer face 20 of the plastic sheet 5. During the subsequent lamination together of the component layer elements 4 to 10 of the device 1, the bent-over outer end portions 22,
23 of the ribbon conductors 11, 12 become laminated to the outer face 20- of the plastic sheet 5 so as to be exposed thereat.
The plastic plug 16, with the plastic-covered wire leads 14, 15 molded and embedded therein, is formed as a separate unit from the plastic encapsulated electroluminescent cell assembly 2 to which it is then subsequently laminated to thereby form the completed wire-terminated electroluminescent device 1 according to the invention. The plastic plug 16 is preferably made of the same thermoplastic material (for example, Kel F or Aclar) as that employed for the encapsulating envelope 3 so as toadhere firmly thereto on lamination together therewith. The two flexible wire leads 14, 15, which preferably consist of a stranded wire core 24 of copper or other suitable metal provided with a coating 25 of a suitable plastic insulating material, for example, a polytetrafluoroethylene material such as that commercially known as Teflon, are molded into the flanged plastic stud 16 soas to extend in close side-by-side relation therethrough and project from its flanged end 26 as well as from its other end. The plastic insulation or coating 25 is then stripped oif the portions of the wires 14, 15 protruding from the flanged end 26 of the plastic st-ud 16 and the bared wires then trimmed to proper length such that, when bent over in opposite directions to lie flat against the face of the flanged end 26 of the plastic stud 16 as shown in FIG. 6, the bent-over bared wire portions 27 will engage and thus electrically contact the exposed outer end portions 22, 23' of the ribbon conductors 11, 12 when the plastic plug 16 is placed in proper position against the wing extension 17 of the plastic evelope 3 with the bent-over wire portions 27 disposed crosswise of and centered over the ribbon conductors, as shown in FIGS. 2v and 7. Although the plastic stud 16 may be of any suitable cross-sectional configuration, its stem portion preferably is of circular cross-section while its flanged end 26 is preferably of rectangular shape and of suflicient size to completely overlie or cover the outer end portions 22, 23 of the ribbon conductors 11, 12 so as to afford protection against electrical shock.
With the plastic stud 16 thus positioned in place against the wing extension 17 on the plastic encapsulating envelope 3 of the device 1, with the bent-over wire portions 27 lying across and in contact with the exposed outer end portions 22, 23 of the ribbon conductors 11, 12, the flanged end 27 of the plastic stud 16 is then laminated, under heat and pressure, to the wing extension 17 of the plastic envelope 3 to thereby complete the fabrication of the electroluminescent device 1 according to the invention. During the laminating operation, the pressing together of the wing extension 17 and the flanged end 26 of the plastic stud 16 causes the bent-over ends 27 of the wire leads 14, 15 to be pressed into firm contact with the outer end portions 22, 23 of the respective ribbon conductors 11, 12, thus forming a good electrical connection therebetiween. In addition, the conductor-receiving slots 21 in the bottom plastic encapsulating sheet 5, as Well as the outer ends 22, 23 of the ribbon conductors 11, 12 and the bent-over portions 27 of the wire leads 14, 15, become completely covered and sealed or closed off from the outside atmosphere by the flanged end 26 of the plastic Slllld 16, thus further assuring the forma tion of a moisture-tight seal of the lead-in conductors 11, 1'2 and wire leads 14, 15 into the device and at the same timekaflording protection against accidental electrical shoe Instead of forming the wire termination 13 according to the invention on a wing extension 17 of the plastic encapsulating envelope 3 of the device, as shown in FIGS. 1 to 4, it may be formed alternatively within a small rectangular or square-shaped corner area 28 of the electroluminescent device 1, as shown in the modification illustrated in FIG. 7. In the case of such a modified form of the invention, the electrically active cell portion 2 of the electroluminescent device is simply notched out at one corner, as indicated at 29 in FIG. 7, to leave the required surface area 28 on the illustrated rectangularly-shaped plastic encapsulating envelope 3- for the formation thereon of a wire termination 13 the same as that shown in, and described above in connection with FIGS. 1-6.
The wire termination 13 according to the invention not only is easy and inexpensive to fabricate, requiring a minimum number of added manufacturing operations and few additional parts, but it also is of sturdy character and not subject to impairment or destruction by the vibrations and physical shocks normally encountered in service. Moreover, the sealing of the ribbon conductors 11, 12 between the two plastic encapsulating sheets 4, 5, coupled with the sealing off of the conductor-receiving slots 21 in the plastic sheet 5 by the flanged end 26 of the plastic stud 16, assures the formation of an effective moisture-tight wire-type termination 13 for the electroluminescent device 1.
Although preferred embodiments of my invention have been disclosed, it will be understood that the invention is not to be limited to the specific construction and arrangement of parts shown, but that they may be widely modified within the spirit and scope of my invention as defined by the appended claims.
What I claim as new and desire to secure by Letters Patent of the United States is:
1. An electroluminescent device comprising an electroluminescent cell assembly sealed between a pair of thermoplastic encapsulating sheets, said cell assembly comprising an electroluminescent phosphor layer sandwiched between a pair of electrically conducting electrode layers, and a wire termination for said device comprising a pair of electrical conductors electrically connected to respective ones of said electrode layers and projecting from the edge of the said cell assembly in substantially side-byside spaced relation, the projecting portions of said conductors being sealed between said plastic encapsulating sheets and having outer end portions extending through the thickness of one of said encapsulating sheets to the outer face thereof and lying flat thereagainst, and a thermoplastic stud having a flanged end laminated to the outer face of said one encapsulating sheet over the said outer end portions of said conductors and having a pair of wire leads embedded therein, said wire leads having bare wire portions projecting from and bent over the flanged end of said plastic stud and engaging the said outer end portions of respective ones of said conductors, the said bent-over bare wire ends of said wire leads being sealed between the flanged end of said plastic stud and the said outer face of said one encapsulating sheet and thereby held in firm pressure contact with the outer ends of said conductors so as to be electrically connected thereto.
2. An electroluminescent device as specified in claim 1- wherein the said one plastic encapsulating sheet is provided with a pair of apertures through which the said conductors extend to the said outer face of said sheet.
3. An electroluminescent device as specified in claim 2 wherein the said conductors are of ribbon form and the said apertures are of slot-shaped configuration.
4. An electroluminescent device as specified in claim 1 wherein the outer end portions of said conductors lying flat against the outer face of said one encapsulating sheet extend in side-by-side relation and the said bare wire portions are bent oppositely away from one another over the flanged end of said stud and extend across and engage the said outer end portions of said conductors.
5. An electroluminescent device as specified in claim 1 wherein the said encapsulating sheets are provided with complementary Wing extensions sealed together and the said wire termination is located on said sealed together wing extensions.
6. The method of making a wire-terminated electro luminescent device which comprises the steps of forming a lay-up comprised of an electroluminescent cell assembly positioned between a pair of thermoplastic encapsulating sheets with a pair of conductors in contact with the respective electrode layers of said cell assembly and projecting from an edge thereof in side-by-side relation, threading the said conductors through respective apertures formed in one of said encapsulating sheets and bending their projecting outer end portions flat against the outer face of said one encapsulating sheet, laminating the said lay-up assembly together under pressure and heat to form a plastic encapsulated electroluminescent device with the outer ends of said conductors laminated to the outer face of said one encapsulating sheet, forming -a plastic stud with a flanged end and with a pair of wire leads embedded therein and having bare wire portions projecting from and bent over its flanged end, and then laminating the flanged end of said thermoplastic stud to the said outer face of said one encapsulating sheet over the said apertures therein and with the said bent-over bare wire portions in contact with the outer end portions of respective ones of said condutcors.
References Cited UNITED STATES PATENTS 5/1959 Destriau 313108 X 8/1959 MacIntyre et al. 313l08 X