Panel And Edge Lighting Assembly

Abstract

An edge lighted panel for use principally in illuminating nomenclature associated with aircraft instruments is provided with front mounted lamps in substantially flush relationship with the front surface of the panel and yet so designed that they may be removed and replaced from the front surface. Electrical energy is provided for the lamps by means of a printed circuit board affixed to the rear of the panel and having conductive paths connecting to leads associated with a filter housing for the lamp received in a bore in the panel itself. The arrangement is such that replacement of the lamps can be effected without having to disturb the panel, filter housing and printed circuit board assembly.

Description

This invention relates generally to edge lighted panel assemblies and more particularly, to an assembly in which miniature lamps may be mounted from the front of the panel and a printed circuit board affixed to the rear of the panel for providing energy for the lamps.

BACKGROUND OF THE INVENTION

Edge lighting of panels is well-known in the art and has wide applicability, particularly in the illumination of instrument, control, and console panels in aircraft. In such panels, light is usually transmitted through the edge of a plastic or light conducting core material. This material is provided with an opaque surface coating except for transparent areas in the shape of letter or numeral characters through which light is emitted. The letter or numeral characters from the nomenclature identifies the control positions of the switches, instruments, and other devices assembled on the panel.

A desirable feature in edge lighted panels of the foregoing type is to provide proper light sources and connections thereto distributed in the panel in a manner which avoids projections on the panel surfaces. In other words, a flush surface is desirable not only to facilitate mounting the panel but to avoid interference with other instruments which are inserted in the panel. In some panels heretofore provided wherein a flush surface is realized, it has been necessary to pot the entire lamp structures directly into the panel itself. However, if a bulb or lamp should burn out, it is an expensive and time-consuming operation to replace the lamp, such operation usually requiring destroying part of the panel structure itself as well as circuit connections to the lamp. As a consequence, many more lamps than actually necessary for proper lighting in such type panels have been required simply to meet defined safety standards.

It will be evident that if a lamp structure could be designed for easy removal and replacement without having to appreciably disturb the remaining portions of the panel, lights could be immediately replaced that are burnt out and thus the overall number of lights presently required for safety purposes would not be necessary all to the end that greater economy and ease of manufacture would be realized.

In U.S. Pat. application Ser. No. 581,011, filed Sept. 21, 1966 and assigned to the same assignee as the present application, there is described a miniature light structure for an edge lighted panel so designed that the light structure is flush with the surfaces of the panel so that there are no projections from the panel. In addition, the lamp structure is so designed that the lamp portion itself may readily be removed and replaced without disturbing the remaining portions of the panels or electrical power connections within the panel.

The foregoing described miniature lamp structure includes a filter assembly having electrical leads connected to buried conductors within the interior of the panel itself. These leads and conductors are potted within the panel and thus the filter assembly becomes a permanent part of the panel. The provision of routed channels in the rear of the panel for receiving power conductors, the connection of these power conductors to the leads of the filter assembly, and the subsequent potting of the entire structure is a time-consuming operation in the manufacture of such panels. Further, there is no ready means of gaining access to the filter assembly itself without destroying the panel and buried conductor connections therein. Thus, while the provision of a panel with readily replaceable lamps is realized by the foregoing described invention in the mentioned pending patent application, there still result certain manufacturing difficulties as noted.

BRIEF DESCRIPTION OF THE PRESENT INVENTION

With the foregoing considerations in mind, the present invention contemplates the provision of an edge lighted panel assembly wherein all of the advantages of the miniature light structure described in the aforementioned pending patent application are realized and yet wherein the panel assembly may readily be disassembled to expose the filter assembly portion of the lamp structure and corresponding electrical connections to power leads.

In accord with the present invention, rather than utilize buried power conductors within the panel itself, there is provided a printed circuit board in combination with the panel. The printed circuit board includes conducting paths exposed in a surface thereof which surface is adapted to be placed in flush face-to-face contact with the rear of the panel. The panel itself includes a plurality of bores for receiving filter assemblies of miniature lamp structures of the type described in the referred to copending application. Towards this end, the panel itself may be provided with channel segments on its rear surface for accommodating laterally extending leads from the filter housing of the lamp structure. An end portion of the filter housing in turn is modified from the structure described in the referred to copending application to include an end portion having both exterior and interior threads. Cooperating with this filter housing is an internally threaded ring member arranged to be threaded to the exterior threads of the end portion of the housing and to seat in a counterbored portion on the front face of the panel. The arrangement is such that the filter housing with associated electrical leads may first be secured to the printed circuit board with the leads in electrical contact with conductive paths of the printed circuit. The panel may then be placed over the filter assembly and the internally threaded ring member then threaded onto the end portion of the filter assembly from the front of the panel thereby holding the printed circuit board, filter housing or assembly, and panel itself together as a composite structure. Thereafter, a cap and lamp assembly may readily be secured into the filter housing from the front of the panel all in flush relationship with the front surface as fully described in the referred to copending application.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the invention will be had by now referring to a preferred embodiment thereof as illustrated in the accompanying drawings, in which:

FIG. 1 is a fragmentary exploded perspective view of a portion of a panel and associated printed circuit board, filter assembly, and cap and lamp assembly forming the basic components of the present invention; and,

FIG. 2 is an enlarged cross section of the elements of FIG. 1 in assembled relationship.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIG. 1 there is illustrated a portion of an edge lighted panel including a light conducting core 10 preferably in the form of a flat sheet of acrylic material having the property of conducting light. The upper surface of the core 10 is first covered with a translucent white substance such as a paint 11 and thereafter with an opaque coating 12. Suitable letters or numeral characters 13 forming desired nomenclature are defined by omitting portions of the opaque coating 12 or removing given portions in the shape of the desired legend to expose the white translucent underpaint.

Distributed throughout the panel are a plurality of bores passing entirely through the panel for receiving suitable light sources generating light which is transmitted by the light conducting properties of the panel core to illuminate the legends such as the characters 13. One of these bores is indicated at 14 and in accord with features of the present invention, includes a counterbored portion 15 on the front surface of the panel defining a recessed area terminating in an annular ledge 16. The rear side of the panel includes channel segments 14a and 14b communicating with the rear exit portion of the bore 14.

A printed circuit board 17 includes first and second conducting paths indicated at 18 and 19. These paths connect with other conducting paths such as 20 and 21 which further paths eventually connect to suitable power input terminal points such as indicated at 22 for the path 20. At certain positions adjacent to the conducting paths, there are provided indexing cavities 23 and 24 for receiving suitable indexing projections on a filter assembly constituting part of the miniature lamp structure.

As shown in FIG. 1, this filter assembly includes a filter housing 25 having laterally extending first and second electrical lead portions 26 and 27. The positions of these leads are such that the same will overlie the conducting paths 18 and 19 respectively when the structure is assembled so as to effect an electrical connection between the paths and leads.

As shown in FIG. 1, the filter housing 25 also includes an externally and internally threaded end portion 28 defining an opening into the housing. The dimensioning is such that the filter housing structure can be received in the bore 14 when the panel 10 is lowered over the structure with the threaded end portion 28 extending into the recessed area above the ledge 16. In this assembled state, the leads 26 and 27 fit within the channel segments 14a and 14b on the underside of the panel.

Shown above the panel 10 is a ring member 29 having internal threads 30. This member is arranged to be threadedly received on the threaded end portion 28 of the filter assembly and to seat on the ledge 16, the top surface of the ring together with the threaded end of the filter housing all being flush with the front surface of the panel.

The edge lighted panel structure is completed by insertion of a cap and lamp assembly designated generally by the numeral 31. This assembly includes a threaded cap 32 arranged to be threadedly received with the internal threads of the end portion 28 of the filter housing. A conducting collar 33 and lamp bulb 34 complete this assembly. The top surface of the cap 32 is provided with a transverse slot 35 for receiving a driver to enable threading and unthreading of the cap and lamp assembly from the filter housing. By this arrangement, the top surface of the cap and lamp assembly will be flush with the front face of the panel when in assembled relationship.

Referring now to FIG. 2, further details of the cap and lamp assembly will be evident. As shown, the filter housing includes a light transmitting filter material 36 surrounding the bulb 34 when the cap and lamp assembly is threaded into the housing. Part of the filter may terminate in projections 37 and 38 which are received in the indexing cavities 23 and 24 respectively in the printed circuit board 17. By this arrangement, the rotative position of the filter housing is such that the electrical lead portions 26 and 27 will properly electrically engage the conductive paths 18 and 19 respectively on the printed circuit board 17 when the same is positioned with its surface in flush engagement with the rear surface of the panel 10.

The lead portion 26 as is clear from FIG. 2 terminates within the filter housing in a central contact 39, preferably in the form of a ring contact through which the bulb 34 extends. The other electrical lead 27 in turn connects directly to the threaded end portion 28 to thus be in electrical engagement through the internal threaded connection 40 with the cap 32.

The conducting collar 33 described in FIG. 1 is shown in FIG. 2 in electrical engagement with the central contact means 39 when the cap and lamp assembly is threaded into the filter housing. This conducting collar 33 is electrically insulated from the cap 32 by an insulating disc 41 and by a suitable insulating retaining collar 42. The disc 41 includes an opening through which one end of a filament lead for the lamp 34 extends to engage in electrical connection the cap 32 as at 43. The other end of the filament of the lamp 34 connects directly to the collar 33 as at 44.

From the foregoing description, it will be evident that when the cap 32 is threaded into the threaded end portion of the housing assembly, electrical connection is effected between the leads 26 and 27 to the lamp filament. In this respect, the central contact ring 39 is normally biased upwardly slightly such that when the collar 33 is moved down against the contact 39, this contact will move into a horizontal plane to thereby provide a reliable connection. The other connection is assured through the threading of the cap 32 as at 40 with the threaded end portion 28.

OPERATION

The operation of the edge lighted panel assembly will be evident from the foregoing description. Preferably, the structure is assembled by first locating various filter housing structures such as the structure 25 of FIG. 1 on the printed circuit board 17. These housings are properly located by means of the projections 37 and 38 described in FIG. 2 and the corresponding indexing cavities 23 and 24 on the board surface. With the various housings properly assembled on the board 17, the leads such as 26 and 27 are soldered directly to the conducting paths of the printed circuit.

Thereafter, the panel 10 with suitable bores such as the bore 14 being formed therein at corresponding locations to the housings on the printed circuit board is simply lowered over the filter housing structures to engage the surface of the printed circuit board in flush relationship. Various ring members such as the internally threaded ring member 29 are then threaded onto the upper protruding end portions of the housing assemblies thus locking the housing assemblies to the panel 10. Finally, the cap and lamp assemblies such as 31 of FIG. 1 may be threaded into the filter housings.

If electrical power is now applied to the conducting paths of the printed circuit board, it will be evident that the various lamps will all be energized in the panel and thus suitable nomenclature and the like will be clearly visible.

Should one of the lamps burn out, it is a very simple matter to unthread the cap and lamp assembly 31 from the filter housing without disturbing the relationship of the filter housing with the panel and printed circuit board. Further, this change of the cap and lamp assembly can readily be effected from the front surface of the panel so that dismounting of the panel is totally unnecessary.

In the event it should be desired to gain access to the filter housing itself, the panel 10 may readily be separated from the filter housing and printed circuit board by simply removing the various ring members 29 from the housing assemblies, access to these ring members again being had from the front of the panel. With the ring members removed, the entire panel may then simply be lifted off of the printed circuit board to leave the filter housings all exposed.

From the foregoing description, it will thus be evident that the present invention has provided an improved edge lighted panel assembly wherein both front and rear surfaces are free of any projections and yet manufacture and assembly is enormously simplified.

Claims

I claim:

1. An edge lighted panel assembly comprising:

a. a panel having a bore passing from its front to rear surface;

b. a printed circuit board having a printed circuit exposed on one surface for carrying electrical power;

c. a filter assembly having electrical leads adjacent to the rear surface of said panel when said assembly is positioned in said bore such that when said printed circuit board is positioned against the rear surface of said panel, said leads are in electrical engagement with said printed circuit;

d. a cap and lamp assembly receivable in said filter assembly from the front of said panel, said leads being electrically connected to said lamp when received in said housing, said bore being counterbored at its front end to define an annular recessed area when said filter assembly is received in said bore; and,

e. an internally threaded ring member threadedly receivable on said threaded end portion and dimensioned to seat in said annular recessed area to thereby hold said filter assembly in said panel, the top surface of said ring member and threaded end portion being substantially flush with the front surface of said panel, and the top of said cap and lamp assembly after being received in said filter assembly being substantially flush with the front surface of said panel,

whereby said cap and lamp assembly may be replaced from the front of said panel without disturbing the assembly of said panel, printed circuit board and filter assembly.

2. An assembly comprising, in combination:

a. a panel comprising a light conducting core in the form of a flat sheet having a front viewing surface and a normally concealed rear surface and including at least one bore of given diameter extending normally entirely through said sheet, said bore being counterbored on the front surface of said sheet to define an increased diameter bore extending into said front surface of said panel a distance less than the thickness of said panel to define an annular ledge with said bore, said panel further including first and second laterally extending channel segments on its rear surface communicating with said bore;

b. a printed circuit board having on one surface a printed circuit defined by at least first and second conducting paths spaced apart by a distance such as to cross said first and second laterally extending channel segments respectively when said surface of said board is affixed in flush relationship to the rear surface of said panel, said board including indexing cavities adjacent to said conducting paths;

c. a filter assembly comprising a lamp housing having an externally and internally threaded end portion defining an opening into said housing; first and second conductors having lead portions extending laterally from the other end portion of said housing opposite said threaded end portion, one of said conductors electrically connecting to said threaded end portion and the other terminating in a central contact means in said housing, said housing including small projections adjacent to said leads, the diameter of said threaded end portion and housing being less than that of said bore and the dimensioning of said conductors being such that said lead portions are receivable in said channel segments respectively when said housing and threaded end portion are passed through said bore from the rear surface of said panel; an internally threaded ring member dimensioned to be threadedly received on the externally threaded part of said end portion and seat on said annular ledge in said counterbore to thereby hold said filter assembly in said panel, the top surface of said ring member and end of said threaded end portion being substantially flush with said front surface of said panel; and

d. a cap and lamp assembly adapted to be threaded into the internally threaded part of said end portion of said lamp housing such that the lamp portion of said assembly is within said housing and the cap portion in electrical threaded engagement with said end portion and flush therewith, the lamp in said assembly having a filament with one end thereof electrically connected to said cap and the other end positioned to be electrically connected to said central contact means when said cap and lamp assembly is fully threaded into said filter assembly, whereby said filter assembly may be positioned on said printed circuit board with said small projections received in said indexing cavities and with said leads crossing said conductive paths and electrically connected thereto so that electrical power may be applied to said leads from said printed circuit board, and said panel may be positioned over said printed circuit board with said filter assembly passing through said bore, and said ring member thereafter threaded to said end portion and finally said cap and lamp assembly threaded into said filter assembly to provide a completed edge lighted panel assembly wherein said cap and lamp assembly may be replaced from the front surface of said panel and wherein there are no projections above said front surface when said cap and lamp assembly is properly threaded into said filter assembly.

3. An assembly according to claim 2, in which said cap includes a transverse slot to receive a driver to enable threading and unthreading of the same.