Electroluminescent panel and method of manufacturing the same

Abstract: An electroluminescent panel and a method of manufacturing the same which comprises the steps of: forming a roll of luminous base film (1) made of phosphors embedded in insulating material, the luminous base film (1) being laminated upon a conductive film (4); forming a roll of a transparent conductive film; passing the luminous base film (1) and transparent conductive film (4) between a pair of rollers (21, 22) while sandwiching a power supply bus bar (7) made of a metal film therebetween, to thereby make the luminous film (1), transparent conductive film (4) and power supply bus bar (7) in an integrated body by means of pressurized heating; cutting the integrated body into a piece having a predetermined length; and mounting a terminal and packaging the piece with a moisture proof film.

Description: Background of the Invention 1. Field of the Invention The present invention relates to an electroluminescent panel and a method of manufacturing the same. 2. Description of the Prior Art As shown in Figs.14 and 15, a conventional electroluminescent panel 20 is manufactured in such a way that a luminous layer 22 composed of phosphors embedded in insulating substance is laminated upon a back electrode (e.g., aluminum foil) to thereby form a luminous base 23. This base 23 is then laminated upon a transparent conductive layer 25 on which a bus bar 24 of a predetermined pattern is printed with conductive paint. The luminous base 23 and the transparent conductive layer 25 is then packaged with a moisture proof film 26 to obtain a finished electroluminescent panel 20. A conventional bus bar 24 is made of conductive paint so that it has an electric conductivity as small as one hundredth to one thousandth of metal material. It is therefore necessary for a large scale electroluminescent panel to use a wide or thick bus bar 24, posing problems of reduction in an effective screen area, increase of production processes, and the like. Further, a bus bar 24 is usually formed by means of screen printing so that the size of the electroluminescent panel 20 is constrained by the dimension of the printing machine. Furthermore, if electroluminescent panels of various sizes are required to be manufactured, the corresponding number of luminous bases 23 are required to be prepared at different production lines, thus posing complicated production management and poor production efficiency. The document Machine Design, no. 18, no. 903, 6 August 1987, page 50 "Flexible Lamp Is Cheaper, Easier To Make" discloses an electroluminescent lamp which is formed by the steps of: forming a roll of an electroluminescent lamp in a sheet consisting of a transparent conductor, a phosphor layer, a bus bar, an -electric layer and an opaque conductor; forming a transparent packaging roller, cutting each roll into a piece, assembling them into an one piece body, and passing this one piece body through heat lamination rollers to form an integrated body, and adding terminals. This method has the drawback that the forming of the electroluminescent lamp is complicated, as the integration of its parts must be carried out manually one by one. As a consequence, no continous integration can be carried out. The US-A-3376177 discloses a process for manufacturing an electroluminescent lamp, wherein an electrically conductive sheet of glass paper is placed over a sheet of metal foil, coated with a particulate layer of phosphor dispersed in a resinous organic media, and passing said glass sheet and said coated metal foil through a roller, thereby bonding said glass paper to that phosphor layer. Summary of the Invention It is therefore an object of the present invention to provide an electroluminescent panel capable of eliminating the above-described prior art problems, while ensuring high electric conductivity of the bus bar without necessiating complicated production management and deteriorating production efficiency. The above object is achieved by the method of manufacturing an electroluminescent panel according to the present invention, which comprises the steps of: forming a roll of a luminous base film, said luminous base film comprising a luminous layer made of phosphors embedded in an insulating material, and an electrically conductive film laminated on said luminous layer; forming a roll of a transparent electrically conductive film; feeding said luminous base film and said transparent conductive film from their respective rolls, passing said fed luminous base film and said transparent conductive film from their respective rolls, passing said fed luminous base film and said fed transparent conductive film between a pair of rollers while sandwiching a power supply bus bar made of a metal film therebetween, to thereby make that luminous film, said transparent conductive film and said power supply bus bar in an integrated body by means of pressurized heating; cutting said integrated body into at least one piece having a predetermined length; and connecting an electrically conductive terminal to said power supply bus bar, and packaging said at least one piece within a moisture proof film with said conductive terminal extending through said moisture proof film and leading to the outside of the moisture proof package. According to the present invention, since the power supply bus bar made of a metal film is used, the bus bar has a high electric conductivity, thereby realizing a large scale electroluminescent panel having a high power supply efficiency. In addition, the luminous base film and transparent conductive film are formed in a roll so that continous production processes are possible to thus realizing a large scale electroluminescent panel with improved productivity. Brief description of the Drawings The present invention will now be described in detail in conjunction with the preferred embodiments while referring to the accompanying drawings, in which: Fig.1 is a perspective view of a luminous base film according to an embodiment of the method of manufacturing an electroluminescent panel of this invention; Fig.2 is a perspective view of a transparent conductive film according to the same embodiment; Fig.3 is a perspective view showing the manufacturing step of a luminous body according to the same embodiment; Fig.4 is a perspective view of the luminous body according to the same embodiment; Fig.5 and 6 are a perspective view and cross section showing the mounting process of a power supply metal foil according to the same embodiment; Fig.7 is a back view showing the packaging process according to the same embodiment; Fig.8 is a cross section taken along line VIII-VIII of Fig. 7; Fig.9 is a perspective view showing the main part of a bus bar according to a second embodiment of this invention; Fig.10 is la perspective view showing the main part of a luminous base film according to a third embodiment of this invention; Fig.11 is a perspective view showing the manufacturing process of a luminous body according to the third embodiment; Fig.12 is a perspective view showing a luminous body according to the third embodiment; Fig.13 is a cross section showing the main part of the packaging process according to the third embodiment; and Figs.14 and 15 are schematic illustrations used for explaining the conventional method of manufacturing an electroluminescent panel. Detailed Description of the Embodiments The preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Fig.1 is a perspective view of a luminous base film 1 according to the first embodiment of this invention. This luminous base film 1 is constructed by laminating a luminous layer 3 upon a metal film 2. The metal film 2 such as an aluminum film of elongated size is used as a back electrode of the electroluminescent panel. The luminous layer 3 is made of phosphors embedded in insulating material. Fig.2 is a perspective view of a transparent conductive film 4 according to the first embodiment. This transparent conductive film 4 is formed by laminating a transparent and conductive ITO film 6 upon a transparent film 5 such as a PET film. The luminous base film 1 and the transparent conductive film 4 are formed in a roll. The rolls of the films 1 and 4 are mounted as shown in Fig.3 so as to make the luminous layer 3 of the luminous base film 1 face the ITO film 6 of the transparent conductive film 4. The films 1 and 4 are passed through a pair of rollers 21 and 22 while sandwiching a bus bar 7 to made the films 1 and 4 in an integrated body by means of pressurized heating. The bus bar 7 is sandwiched between the films 1 and 4 at one side portion of the films. The bus bar 7 is made of a metal foil such as copper, phosphor bronze, or aluminum. The integrated luminous body 8 thus formed is shown in Fig. 4. As shown, the bus bar 7 is integrally sandwiched between the luminous base film 1 and transparent conductive film 4. The integrated luminous body 8 is then cut into pieces having desired lengths. As shown in Figs.5 and 6, an insulating both-side adhesive tape 9 is attached at the end portion of the bus bar 7. A power supply metal foil 10 is attached onto the tape 9, the foil 10 being made of copper, aluminum or phosphor bronze. The tape 9 is positioned under the bus bar 7, whereas the metal foil 10 is positioned above the bus bar 7. Thereafter, as shown in Figs.7 and 8, lead terminals 11 are connected to the metal film 2 of the luminous base film 1 and to the power supply metal foil 10. This arrangement with respect to the lead terminals 11 is the same as a conventional electroluminescent panel, so the detailed description therefor is omitted. The luminous body 8 with the lead terminals 11 connected is then packaged with a moisture proof film 12 to complete an electroluminescent panel of the first embodiment. The electroluminescent panel manufactured as above has the bus bar 7 made of a metal film embedded within the panel. Even if a narrow and thin bus bar is used, a sufficient conductivity is ensured without significant voltage drop, thereby realizing a large effective luminous screen area even for a large scale panel. Further, the luminous body 8 may be cut in any desired size, small or large, according to the size of an electroluminescent panel. Fig.9 is a perspective view of a bus bar according to the second embodiment of this invention. In this embodiment, the bus bar 7 is constructed of a metal foil 7a such as copper, phosphor bronze, or aluminum and an insulating adhesive layer 7b. This bus bar 7 is sandwiched between the luminous base film 1 and transparent conductive film 4 in the same manner as described with Fig.3 to be formed into an integrated luminous body 8. The insulating adhesive layer 7 is mounted facing the luminous layer 3 of the luminous base film 1. When the luminous body 8 is cut at the later process into pieces having desired lengths, the metal foil 7a may be bent or cut unevenly to contact the metal film 2 of the luminous base film 1. The insulating adhesive layer 3b prevents such undesired contact and thus ensures a reliable electroluminescent panel. The other arrangement of the second embodiment is the same as the first embodiment, so the detailed description therefor is omitted. Fig.10 shows the third embodiment of this invention. The luminous base film 1 of this embodiment is also constructed of a laminated film of a metal film 2 and luminous layer 3, in the same manner as the first and second embodiments. However, in this embodiment, through-holes 1a are formed along one side portion of the luminous base film 1. The luminous base film 1 and the transparent conductive film 4 (refer to Fig.2) each in a roll form are mounted as shown in Fig.11 so as to make the luminous layer 3 of the luminous base film 1 face the ITO film 6 of the transparent conductive film 4. The films 1 and 4 are passed through a pair of rollers 21 and 22 while sandwiching the bus bar 7 to make the films 1 and 4 in an integrated body by means of pressurized heating. The bus bar 7 is sandwiched between the films 1 and 4 at the position where the through-holes 1a are formed. The integrated luminous body 18 thus formed is shown in Fig.12. As shown, the bus bar 7 is exposed at the through-holes 1a. As described with the first and second embodiments, the integrated luminous body 18 is then cut into pieces having desired lengths. As shown in Fig.13, the integrated luminous body 18 is packaged with a moisture proof film 12 by heating process to complete an electroluminescent panel. In the cutting process of the luminous body 18, each piece is cut so as to include at least one through-hole 1a. Since the luminous body 18 cut into a piece has at least one through-hole 1a, the bus bar 7 is exposed therefrom. a lead terminal 11 for the transparent conductive film 4 can be directly connected to the exposed portion of the bus bar 7, thus allowing an easy connection. As described so far, according to the present invention, both the luminous base film and transparent conductive film are formed into an integrated luminous body while sandwiching the power supply bus bar made of a metal film therebetween. The electric conductivity of the power supply bus bar is therefore improved considerably with less voltage drop, thereby realizing a large scale, especially elongated, electroluminescent panel which has been heretofore impossible to be manufactured. Further, through-holes are formed in the luminous base film at predetermined intervals along one side portion thereof so that the bus bar is exposed through the holes. As a result, connection of a lead wire for the transparent conductive film cut in small can be made easily. In addition, electroluminescent panels of various sizes can be readily manufactured from the rolls of two films, thus improving the production efficiency while ensuring cost effectiveness.

Claims: A method of manufacturing an electroluminescent panel comprising the steps of: forming a roll of a luminous base film (1), said luminous base film (1) comprising a luminous layer (3) made of phosphors embedded in an insulating material, and an electrically conductive film (2) laminated on said luminous layer (3) ; forming a roll of a transparent electrically conductive film (4) ; feeding said luminous base film (1) and said transparent conductive film (4) from their respective rolls, passing said fed luminous base film (1) and said transparent conductive film (4) from their respective rolls, passing said fed luminous base film (1) and said fed transparent conductive film (4) between a pair of rollers (21;22) while sandwiching a power supply bus bar (7) made of a metal film therebetween, to thereby make said luminous film (1), said transparent conductive film (4), and said power supply bus bar (7) in an integrated body (8) by means of pressurized heating; cutting said integrated body (8) into at least one piece having a predetermined length; and connecting an electrically conductive terminal (11) to said power supply bus bar (7), in said at least one piece and packaging said at least one piece within a moisture proof film (12) with said conductive terminal (11) extending through said moisture proof film (12) and leading to the outside of the moisture proof package. A method of manufacturing an electroluminescent panel according to claim 1, wherein connecting of said electrically conductive terminal (11) to said power supply bus bar (7) is achieved by mounting said electrically conductive terminal (11) to said at least one piece in direct contact with said power supply bus bar (7) and leading to the outside of said integrated body. A method of manufacturing an electroluminescent panel according to claim 1 or 2, wherein said power supply bus bar (7) includes a metal film (7a) and an insulating adhesive layer (7b) attached to one side of said metal film (7a). A method of manufacturing an electroluminescent panel according to claim 1, wherein connecting said electrically conductive terminal (11) to said power supply bus bar (7) is achieved by connecting said electrically conductive terminal (11) through at least one of said through-holes (1a) to said power supply bus bar (7) which is in contact with said transparent conductive film (4). An electroluminescent panel comprising: a luminous base film (1), said luminous base film (1) comprising a luminous layer (3) made of phosphors embedded in an insulating material, and an electrically conductive film (2) laminated on said luminous base film (1) having at least one through-hole (1a) at one side portion thereof; a transparent electrically conductive film (4); a power supply bus bar (7) sandwiched between said luminous base film (1) and said transparent conductive film (4) at the position facing at least one through-hole (1a); whereby a power supply lead wire (11) for said transparent conductive film (4) is connected to said power supply bus bar (7) via said at least one through-hole (1a).

Inventors: HASEGAWA KAZUHIRO, KAGAWA MITSURU, KANEMITSU NOBUHISA, KONDO FUMIO, MOCHIZUKI SHIGEHIRO, MORI KIJU, WATANABE JUNICHI, HASEGAWA, KAZUHIRO, KAGAWA, MITSURU, KANEMITSU,NOBUHISA, KONDO, FUMIO, MOCHIZUKI, SHIGEHIRO, MORI, KIJU, WATANABE, JUNICHI
Applicants: STANLEY ELECTRIC CO LTD, STANLEY ELECTRIC CO., LTD.
Application year: 1989
Main classification: H05B33
IPC codes: H05B33