FIELD OF INVENTION

This invention relates to a fiber optic lens and lamp assembly for use with flat multi-wire cables intended for use in lighting systems under carpets or rugs. The invention works particularly well with a flat cable laminated assembly.

This application is assigned to the assignee of U.S. application Serial No. 899,494, filed August 22, 1986, entitled MULTI-CONDUCTOR CABLES, which is herein incorporated by reference.

BACKGROUND OF THE INVENTION It has recently become common for management of hotels, theaters and other public gathering places to incorporate some type of lighted direction system in their hall and room carpets so that, in case of fire or other emergency, the light system can be intermittently lighted to direct guests to a safe exit. The lights may assume the pattern of arrows or sequentially flashing lights or a number of other configurations. Normally, the illumination system includes a flat, multi-wire cable installed beneath the carpet. Small lamps are connected to this cable. Either the lamps themselves or associated electric leads pass through holes in the carpet.

Several types of multi-cable assemblies exist. One type includes closely bunched wires. Another type includes parallel, closely spaced flat copper conductors laminated between two multi-ply plastic sheets. A third type, described in the above- referenced patent application No. 899,494, features a lamination of a plurality of flat, tinned copper strip

conductors, laminated between a pair of organic plastic insulating sheets, which sheets adhere tightly to each other but at least one of which does not adhere to the copper strip conductors. Power is supplied to each of the conductors and the light bulbs are arranged in any desired pattern, receiving power from the conductors.

A number of configurations for providing and distributing the power to the lamps have been proposed. In one configuration, one of the conductors includes a plurality of electrically isolated portions each of which is electrically connected to a respective one of the other conductors. The light bulbs are placed along the segmented conductor, one lead connected to a conductor segment, the other connected to a common bus conductor, and a switching mechanism controls the sequence of lighting by selectively providing power to the other conductors.

The connections between the segmented conductor and the others may be either by a simple wire or may be by a portion of the segmented conductor itself, which has been cut from the remaining length, folded back upon itself and at right angles to the major portion of the conductor, so that it crosses neighboring conductors to join the desired second conductor. Of course, insulation must be provided to prevent electrical contact between the folded connecting conductor and the underlying conductors. It is possible to utilize the adhered plastic laminated sheet for this purpose.

In another scheme, the cross connections may be provided by a plurality of conductor connecting patterns carried on one of the plastic insulating sheets, typically printed thereon using a conductive graphite, nickel or silver ink. An electrical

resistance heater, using conductive patterns printed on insulating sheets is disclosed in co-assigned U.S. Patent No. 4,485,297, issued on November 27, 1985, which is incorporated herein by reference.

Known lamp and lens assemblies for use with flat, multi-wire cables under carpets have drawbacks. A typical assembly includes a lamp fixture and a light- emitting diode or a small light bulb with a protective plastic cover. These are fragile. The bulbs or diodes are in a place where they receive constant abuse from marching pedestrians. The hard plastic case of the bulb, and the bulb itself, may break. Further, during installation, relatively large holes must be cut in the carpet so that the plastic cover may protrude and provide illumination. Finally, the covers are always visible and detract from the aesthetic effect of most carpets. This provides a constant and unpleasant reminder to the guests that hazards sometimes arise.

SUMMARY OF THE INVENTION The principal aspect of the invention is a lens and lamp assembly, where the lens is a bundle of optical fibers having one end fused together before installation of the lamp/conductor sheet and laying of the carpet. Only the end is fused, the mid-portions of the fibers remaining individual. The fused end is later cut off to separate the formerly fused bundle of fibers. This feature permits easy installation. The fiber bundle, with fused ends, is a rigid projection over which a carpet may be simply laid. After the carpet has been laid, the fiber bundles are cut at a non-fused region, flush with the top surface of the carpet. The fiber bundle spreads out providing a multiplicity of pinpoint light sources. The fibers of

the bundles are very small in diameter, and similar in structure and appearance to the fibers of a carpet. Further, the optical fibers reflect the color of the carpet and may be supplemented with reflecting metallic elements so that they are virtually unnoticeable. Thus, the fiber bundle lens does not detract from the aesthetics of the overall interior decoration of the public space, nor does it needlessly remind patrons of the unpleasant situations giving rise to their need.

Further, the fiber bundles are flexible and better withstand the abuse of overtreading pedestrians.

The invention also includes a method for installing the fiber bundle-type lens system. According to this method, the fused fiber bundles and a lamp holder are secured at one end in the plastic cable assembly so that the upwardly protruding fiber bundles are longer in length than the pile depth of the carpet. The unsecured end of the fiber bundle is fused, so that the fiber bundle assumes a rigid configuration. Holes are provided in the carpet corresponding to the locations of the fiber bundles. Because one end of the bundle is fused, the holes may be relatively small as compared to the ultimate diameter of the spread fiber bundles after cutting off of the fused portion. The fiber bundles may be identical for a variety of applications, regardless of carpet pile depth. They must be longer than the deepest pile normally in use. This provides a distinct advantage over conventional lenses, which must be sized for the particular carpet pile. Thus, stock variety may be minimized by merchants and installers.

DESCRIPTION OF THE FIGURES OF THE DRAWING

FIG. 1 is a perspective view, slightly simplified and partially in section, illustrating the present invention installed as a constituent member of a flat conductor light and cable system.

FIG. 2 is a cross section of the invention showing the fiber optic lens, lamp and lens holder.

FIG. 3 is a plan view showing one embodiment of the lens holder.

DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows a multi-conductor, flat cable assembly, generally designated 10, of the type disclosed in the aforementioned and incorporated by reference Serial No. 899,494. A plurality of tinned copper strip conductors 12a-12f, each of which is .008 cm. (.003 in.) thick, and .6 cm. (.25 in.) wide, is hermetically sealed between two sheets of organic plastic insulating material designated 14 and 16.

Sheet 14 is of polyester ("Mylar"), and is approximately .008 cm. (0.003 in.) thick. Sheet 16 is a two layer co-laminate of polyester .005 cm. (0.002 in. thick) and polyethylene .008 cm. (0.003 in.) thick oriented with the polyethylene layer 15 facing, and in face-to-face contact with, the bottoms (as viewed in FIG. 1) of copper strip conductors 12 and the portions of polyester sheet 14 between conductors 12 and along the marginal edges of the assembly 10. In FIG. 1, portions of the upper sheet 14 are removed for clarity. In usual practice, sheets 14 and 16 are transparent. Transparency facilitates locating the conductors for soldering and installation.

As shown, strip conductors 12a-12f are parallel to each other, and the distance between adjacent strip conductors is .635 cm. (.25 in.).

Sheet 16 is bonded to copper strip conductors 12a-12f, to the portions 20a-20e of sheet 14 between adjacent strip conductors 12a-12f, and also to the marginal edge portions 22 of heater 10. The polyester layer 15 of sheet 16 may act as a hot melt adhesive and bond to the bottoms of copper strip conductors 12a-12f and to the portions 20a-20e and 22 of sheet 14 that are in face-to-face contact with the sheet 16. The bond is a heat seal made by passing sheets 14 and 16, with copper strip conductors 12a-12f therebetween, through a conventional laminating machine in the general manner described in more detail in U.S. Patent applications Serial Nos. 478,080 and 796,012, filed November 7, 1985, which are co-assigned to the assignee hereof, and. which are herein incorporated by reference. There is no bond between sheet 14 (which is all polyester and has no polyethylene or other adhesive layer) and the copper strip conductors»

In the flat conductor assembly of FIG. 1, the areas between adjacent copper strip conductors 12a-12f include a number of holes 24 through the sealed- together plastic sheets 14, 15, 16. As shown, the holes 24 are each about .32 cm. (.125 in.) in diameter and are arranged in lines extending longitudinally of cable assembly 10 midway between adjacent pairs of conductors 12a-12f. The diameter of the holes is less than the distance between conductors thereby insuring that the bonded-together plastic of sheets 14, 16 between the edges of the holes and the copper strip conductors 12 on either side of each hole provide both electrical insulation and hermetic sealing.

FIG. 1 also shows, schematically, several lamp and lens assemblies 70b-70e connected to the flat conductor cables. As shown, conductor 12a acts as a common conductor or ground, and one lead 72' of each

lens and lamp assembly is connected to it. The other lead 72" of each lamp is connected to a respective one of the other conductors 12 (e.g., the other lead of lamps 70c is connected to conductor 12c). In FIG. 1, the leads 72', 72" are indicated in dashed lines, and the points of connection to the conductors by "X's". All of the conductors may be connected to a conventional switching assembly, not shown. Lamp 70b is illuminated when the switching assembly supplies power across conductors 12a and 12b, lamp 70c is illuminated when power is applied across conductors 12a and 12c, and so forth. The connections between the lamp and the conductors are made by leads 72' and 72" to the common ground and to the selected conductor respectively. These leads may take any suitable form known to one of ordinary skill in the art, including but not limited to, insulated wires, cut and folded strips of the flat conductors 12a-12f themselves, or semiconductor patterns printed upon the plastic sheets 14 and 16. U.S. Patent Application No. 899,494, filed on August 22, 1986, and incorporated herein by reference, shows several methods of providing such leads or conductors.

Installation of the lamps on the plastic sheet is facilitated due to the tinning of the copper conductors, and the melting temperature of the plastic sheet 14. It is possible to use conventional automatic soldering equipment to solder directly through the plastic insulating sheets. With respect to mounting the cable assembly 10 on a floor below a rug, nails or staples may be driven through the plastic spaces 20a-20e between adjacent copper strip connectors 12a-12f to hold the assembly in place. Holes 24 permit sufficient air flow to avoid undesirably trapping moisture between the cable

assembly and the floor or other surface on which it is mounted.

FIGS. 2 and 3 illustrate the lens and lamp assembly of the present invention. FIG. 2 is a cross section including a schematic of the lamp. FIG. 3 is a plan view of the lens and lamp holder.

A lens and lamp holder generally designated 30 is provided. The holder illustrated is of a generally circular configuration, however, other configurations may be used. The holder includes a flat disk-shaped base portion 32, which carries a concentrically located lens and lamp housing 34. In the preferred embodiment, the housing has an axis of rotational symmetry. This is not necessary, however, and the housing may have a wide variety of shapes, including a rectangular box shape or a channel relatively longer than it is deep. The housing has two annular portions 36, 38, one located at each end of the axis of revolution of the housing. Each annulus is open at one axial end and capped at the other axial end by a web portion 37. The bottom annulus 38 is sized to receive a lamp 40 which may be a light-emitting diode or a small incandescent bulb. Typically, both annuli 36,38 will have a cylindrical radially inner surface. Leads 42 and 44 are provided to connect the lamp to a voltage source. These leads pass through recess channels 46 and 48 provided on the underside of the disk base portion 32.

The lens is generally designated 50. It comprises a bundle 52 of optical fibers 54 about 1.2 cm. (.5 in.) long. The fibers are generally acrylic optic fibers of between .003-.01 cm. (.001 to .005 in.). Initially, the bundle of fibers are prepared so that all of the fibers are attached (typically fused) together at one end portion 56 of the bundle. The

region 56 (typically about .3 cm. (1/8 in.) long) of the fibers may be attached together or fused by any conventional means known to the art. The other end portion of the fibers (also typically about 1/8 in. long) is secured inside the top annulus 36 (typically using a tufting machine, in a method similar to that by which bristles are secured in a toothbrush head) with the axial ends of the fibers abutting web 37. The fibers may also be secured in annulus 32 by other means known to the art, such as adhesives or heat fusion. If desired, the ends of the fiber bundle within annulus 36 may be fused together also; in which case care must be taken to insure that the fibers remain unfused to each other over the mid-portion (typically about half the overall length of the bundle) of their length. It should be noted that the overall length of the fiber bundle and the lengths of the unfused portions depends upon the depth of the pile of the carpet to cover the lamp fixture. For instance, for a deep pile carpet, the entire length may be approximately 1 inch. The length of the fused end portion need not vary with pile depth.

With respect to the method of installation with a carpet, after the lens and lamp holder assembly 30 has been fixed to the flat conductor strips 12, and wired into the electric circuit, a carpet or rug is.laid over the cable assembly 10. Holes are cut in the carpet corresponding to the location of the fiber optic lamp assemblies.

The fiber optic bundles 50, remain fused at this stage. Fusing facilitates passing the fiber optic bundles through the holes in the carpet. Because the ends of the fiber optic bundles are smaller in diameter when fused than they would be if free, the holes in the carpet may be small. It is an easy

matter to thread the stiff bundles through the holes. If the bundle ends were free, it would be much more difficult, if not impossible, to do so=

After the carpet has been laid, each fiber optic bundle is trimmed so that the fused end portion is removed. The cut may take place at or below the region generally indicated at 58 in FIG. 2. This region should be selected, of course, so that all the fused fiber ends are removed and the remaining optical fibers extend to approximately the top of the carpet pile.

According to one embodiment of this invention, some of the fibers may be aluminized so that they reflect the color of the carpeting, thereby further camouflaging the already unobtrusive fiber optic lens.

Other embodiments of the disclosed invention will be readily apparent to those of ordinary skill in the art. The invention is not limited to the type or size of lamp, or the type of floor covering. Further, it is not limited to use with a floor covering. For example, this invention may be used for illumination on athletic fields utilizing artificial turf. It may also be used on vertical or ceiling walls of buildings covered by a wall covering having some thickness or depth. It may be used in airplanes, ocean liners, or any means of transportation. The circular configuration of the base and housing is not critical and may be rectangular or any other suitable shape.

Having thus described the invention, what is claimed is: