2. Description of the Prior Art Phosphor materials are defined as organic or inorganic liquid or crystalline materials capable of luminescence, i.e., of absorbing energy and emitting a portion of such energy in the UV, visible or infrared regions. When the emission of the substance ceases immediately after excitation, the material is said to be fluorescent. Phosphor material that continues to emit light for a period after the removal of the exciting energy is said to be phosphorescent.

While such materials are known, prior phosphor devices have tended to be of rigid construction and generally not suited for portable use. Thus, phosphors are used in fluorescent light tubes, television, radar and cathode ray tubes, instrument dials and scintillation counters. As can be appreciated, devices of this character cannot readily be worn or used as portable warning lights for example, even though their phosphor characteristics would otherwise make them very advantageous for such end uses.

SUMMARY OF THE INVENTION The present invention overcomes the problems outlined above and provides an illuminable phosphor device which is designed to operate using a high-voltage power source to give a highly visible phosphorescent response. In preferred forms, the device of the invention may be flexible and thus usable in a wide variety of contexts such as wearable belts or other items used by joggers or road workers as a warning to approaching motorists.

In preferred forms, the illuminable devices of the invention include a substrate presenting a pair of opposed faces with a phosphor material on one face of the substrate.

Power means is electrically coupled with the phosphor material for applying a high- voltage operating current of from about 500-1500 volts at 1500-3500 cycles per second to the phosphor material for excitation and consequent illumination thereof. Normally, electrically conductive material is applied to the opposite side of the substrate, and respective electrical leads are in electrical contact with the conductive material and adjacent the phosphor material; these leads are in turn connected to a source of high- voltage electrical current.

The phosphor material advantageously includes a fluorescent or phosphorescent compound such as zinc sulfide together with a minor amount of an activator compound such as copper acetate. The fluorescent or phosphorescent compound is typically present in substantial excess by weight, e.g., at a level of from about 60-97% by weight of the overall phosphor material, while the activator compound is used at a level of from about 1-10% by weight on this basis.

The power means associated with the devices of the invention may be designed for intermittent on-off illumination or constant on illumination.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view of an elongated, flexible, illuminable phosphor device of the invention, depicting the phosphor material-bearing face thereof; Fig. 2 is a view similar to that of Fig. 1 but illustrating the opposed face of the device bearing an electrically conductive layer; Fig. 3 is an enlarged sectional view taken along line 3-3 of Fig. 1 and illustrating in detail the construction of the phosphor device; Fig. 4 is a schematic depiction of one preferred operating circuit usable for generating operating current for the phosphor device illustrated in Figs. 1-3; Fig. 5 is a view illustrating use of the preferred phosphor device as a part of an illuminable warning belt worn by ajogger; and Fig. 6 is a fragmentary side view illustrating a phosphor device in accordance with the invention mounted on the sidewall of a railroad box car to provide illumination thereon.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawings, and particularly Figs. 1-3, a luminesce flexible body 10 is depicted. Broadly speaking, the body 10 includes an internal, continuous, phosphor-bearing substrate 12, a pair of conductive leads 14, 16, and an outer sheath 18.

The phosphor-bearing substrate 12 includes a central sheet of cut white Mylar film 20 presenting a series of generally rectangular, elongated cells 22 interconnected by narrow elongated strips 24. The front face 26 of film 20 is illustrated in Fig. 1 and has a phosphor composition layer 28 applied thereto. A sheet of "egg-shell white" thin Mylar 30 is applied over the phosphor composition layer 28 and is cut to mate with the central white Mylar film 20. The substrate 12 further includes on the rear face 32 thereof (Fig. 2), a continuous layer of pyrotechnic aluminum 34 which is cut in general conformity with the film 20 but inboard from the marginal edges thereof so as to present margins 36, 38 of white Mylar about the peripheries of the cells 22 and strips 24.

Each of the leads 14, 16 are of identical construction but as explained are of different length. Each such lead includes a central ribbon 40 of the same white Mylar material as used for the film 20, and has on each opposed face thereof a layer 42, 44 thereof of conductive material preferably made up of the phosphor composition mixed with a small amount ofthe pyrotechnic aluminum material. The shorter lead 14 extends from one end of the body 10 and is in direct contact with the pyrotechnic aluminum layer 34. The longer lead 16 likewise extends from the same end of body 10 as lead 14, but extends substantially the full length of the body astride the respective cells 22 and strips 24. It will be observed in this respect that the lead 16 is, by virtue of the configuration of the pyrotechnic aluminum layer 34 and the presence of the dielectric Mylar film 20, out of direct electrical contact with the pyrotechnic aluminum. As best seen in Figs. 1 and 2, the outer ends of the flexible leads 14, 16 are equipped with metallic contacts 46, 48.

The sheath 18 is advantageously in the form of a pair of outermost clear Mylar sheets 50, 52 which sandwich the substrate 12 and leads 14, 16 therebetween and thus seal the body 10.

In one preferred form, the body 10 is very lightweight and flexible and, in combination with an appropriate power source and electrical circuitry described below, can provide a highly advantageous safety belt 54. This is illustrated in Fig. 5 in use by a jogger. As shown, the overall belt apparatus 54 includes a body 10 of sufficient

length to encircle the waist of the wearer, with a small electrical pack 56 attached to the belt 10. The mating ends of the belt 54 are provided with complemental Velcro material so as to permit attachment thereof about the waist of the wearer. in preferred forms, the belt apparatus 54 is designed to operate in an intermittent "on-off' fashion so as to warn motorists of the presence of the runner. It will be appreciated that, however, a steady on-off operation could also be adopted with appropriate circuitry modifications.

The electrical circuitry 58 within pack 56 is illustrated in Fig. 4. The preferred electrical circuitry 58 includes a pair of input leads 60 for connecting to a suitable power source such as a 9-volt DC battery, a switch 62, a transistor 64, an integrated circuit 66, resistors 68, 70, 72, capacitors 74, 76, and transformer 78. The preferred switch 62 is a single-pole-double-throw (SPDT) switch. The preferred transistor 78 is an NPN-type transistor. The preferred integrated circuit 66 is a CMOS quad dual input Nand integrated circuit having two series-connected Nand gates per side. The preferred resistors 68, 70, 72 have values of 10K Ohm, 10K Ohm, and 10 Ohm, respectively. The preferred capacitors are each 10 micro farad.

When the switch 62 is closed, the battery sets up a voltage at the collector of the transistor 64 and powers the integrated circuit 66. The integrated circuit 66 generates a pair of identical sine wave signals and sends the first signal to resistor 68 and capacitor 74 and the second signal to resistor 70 and capacitor 76. The capacitors 74 and 76 store the signals and create pulses when they reach their saturation voltage. The pulses from capacitor 74 are then delivered to one side of the primary coil of the transformer 78, and the pulses from capacitor 76 are sent to transistor 64. The transistor 64 shifts the pulses from the capacitor 76 1800 relative to the pulses from capacitor 74 and then sends the phase shifted pulses to the other side of the primary coil of the transformer 78.

The transformer 78 steps-up the pulses generated by the capacitors 74, 76 to provide a high-voltage, low-amperage signal to the leads 14, 16. The transformer 78 preferably generates an 800-volt, 425 miliamp output signal. The transformer also acts as a filter to smooth out the output signal and provides a time constant for the output signal. The time constant, which determines the discharge intensity, is determined by the number of windings in the coils of the transformer 78. The time constant and discharge intensity of the transformer 74 can be changed by changing the resistance of resistors 68, 70 and the capacitance of capacitors 74, 76.

In another embodiment of the electrical circuitry 58, the resistor 72 is replaced with a 1 OK ohm potentiometer. This allows the time constant and discharge rate of the circuitry 58 to be varied by selectively adjusting the value of the potentiometer.

Additionally, the SPDT switch 62 may be replaced with a single-throw-double-pole (STDP) toggle switch that can be toggled between an off position, a steady-on position, and a blinking-on position. When the STDP switch is toggled to its steady-on position, it bypasses the capacitors 74, 76 and therefore eliminates the pulsing or blinking effect of the capacitors.

The high-voltage, low-amperage output signal generated by the transformer 74 is delivered to the contacts 46, 48 of the leads 14,16. Since the lead 16 is spaced slightly from lead 14, a charge builds up in the lead 16 and "flashes-over" to the lead 14 and the aluminum layer 34 when the lead 16 reaches its saturation. This effectively energizes the phosphor layer 28 causing it to illuminate.

Those skilled in the art will appreciate that the principles of the invention may be used in the construction of illuminable bodies of virtually any size and shape for a variety of end uses. Fig. 6 illustrates one such use in the context of a railroad box car B. As shown, the box car is equipped with an elongated, illuminable phosphor strip 110 which for purposes of illustration only is shown as having rectangular cells 122 and interconnecting strips 124. In an embodiment of the type illustrated in this figure, the body 110 would typically be designed for a continuous on operation.

EXAMPLE The following example sets forth the details of construction of a flexible illuminable phosphor body 10. It is to be understood that this example is provided by way of illustration only, and nothing therein should be taken as a limitation upon the overall scope of the invention.

The body 10 shown in the drawings was produced as follows. First, a conventional sliding door track was obtained having a bottom wall and a pair of upstanding sidewalls. The interior surface of the bottom wall of the track was configured to present a series of elongated, axially spaced apart, rectangular openings interconnected by thin passageways. In order to use this door track as a template, the sidewalls were removed leaving a basically flat plate having the described openings therein. In the next step, white Mylar film having a thickness of 2 mil was carefully cut using a razor blade to conform with the plate openings, i.e., the cut white Mylar film 20

presented a series of rectangular segments or cells 22 corresponding to the rectangular openings in the plate, with thin strips 24 between and interconnecting the cells 22 and corresponding with the plate passageways.

In the next step, an approximately 100-gram batch of phosphor material having the composition described in Table 1 was prepared.

Table 1. Composition of phosphor material Ingredient* Quantity (grams) Zinc sulfide 90 Copper acetate 6 Zinc Oxide 1.5 Silicone Oil <1.5 Carbazole <1.5 Cadmium Sulfide <0.5 Anthracene <0.5 *All ingredients were high purity reagent grade powders.

The phosphor ingredients described in Table 1 were thoroughly mixed and laid upon a tray in a tube furnace and fired at 650"C for 2 hours, with nitrogen flowing through the furnace. The nitrogen gas was first passed through sulfur monochloride liquid before entering the tube furnace. After the 2-hour firing, the furnace was cooled to about ambient for 0.5 hour in the nitrogen atmosphere. After cooling, the fired phosphor material was crushed. The crushed material contained dark impurities which were soluble in thiosulfate solvent while the phosphor material was not. The dark impurities were removed from the phosphor material by washing the crushed phosphor material five times with the thiosulfate solvent using a filter. The phosphor material was then finally washed with water, and air dried with the aid of a small fan and a heat lamp. The washed, dried phosphor material was then recrystallized with toluene, and air dried once again.

Another 1.5 grams of a mixture of silicone oil, carbazole, and anthracene was added to the recrystallized phosphor material to give the phosphor material a bluish hue

and the consistency of a paste. A layer of phosphor material 28 was then applied to the entirety of the front face 28 of the cut white Mylar film 20 on the template using a small artist's brush. This phosphor material was then allowed to air dry.

The phosphor material-bearing Mylar film 20 was then reversed and again placed in the template with the rear face 32 thereof upward. Reagent grade pyrotechnic aluminum was mixed with a small amount of silicone oil to form a paste was then applied as a layer 34 to the rear face 32 ofthe Mylar film 20 using a small artist's brush.

The pyrotechnic aluminum layer 34 was then trimmed using a razor blade such that it conformed in shape to the cut white Mylar film 20 and presented the uncovered margins 36, 38.

The leads 14-16 shown in the drawing were prepared as follows. The phosphor material described above was first mixed with 6% by weight of the pyrotechnic aluminum and a small amount of silicone oil to give a conductive paste. Layers 42, 44 of this conductive paste were applied to both sides of a 2-mil-thick white Mylar sheet 40 in the manner described above. Leads having a width of 1/16" were then cut from this coated Mylar sheet using a razor blade.

It was found that the phosphor layer 28 tended to flake off from the Mylar film 20. Accordingly, in order to provide additional support, egg-shell white thin Mylar was cut using a razor blade to conform with the interconnected cells 22 and stirps 24 of film 20. This precut Mylar reinforcement 30 was then placed atop the phosphor layer 28 in registry with the underlying Mylar film 20.

The Mylar film 20 and reinforcement 30 were then centered atop a 0.5" wide strip of clear base Mylar 50 having a thickness of 6 mil. A long lead 16 was laid atop the base Mylar 50 strip adjacent to but spaced from the pyrotechnic aluminum layer 34, and extended from one end of the clear Mylar base 50 to the other. The short lead 14 was also placed atop the Mylar base 50 generally parallel to the first lead. The lead 14 extended from one end of the base 50 and into direct electrical contact with the pyrotechnic aluminum layer 34 of the proximal cell 22. A second 0.5" wide strip 52 of clear Mylar having a thickness of 2 mil was then laid atop the phosphorescent film/lead assembly. The resulting sandwich was ironed with a standard clothes iron to fuse the two clear Mylar strips together. A pair of metal electrical contacts were attached to the end of the fused Mylar strips 50, 52 such that each contact was electrically connected with one of the sandwiched leads 14, 16.

In order to form a complete safety belt device 54, the body 10 is attached to a belt of webbing, preferably by positioning the body 10, with the front face 26 thereof

facing outwardly, beneath a transparent synthetic resin sheet; the latter is secured to the outer face of the webbing by stitching. In addition, the metallic contacts 46, 48 are attached to the outputs of circuitry 58 as described, the latter being housed within pack 56.

As indicated, a wide variety of different specific phosphor materials and corresponding conductors can be used in the context of the invention. Generally, the phosphor materials of the invention will include a phosphor together with an activator.

The phosphors are preferably selected from the group consisting of fluorescent or phosphorescent compounds of zinc, cadmium, mercury and germanium, with zinc sulfide being the most preferred phosphor. The activators are preferably selected from the group consisting of compounds of copper, manganese, bromine, iodine, and cadmium, and most particularly the chloride and acetate salts. in the preferred phosphor material of Table 1, the phosphor employed was zinc oxide, whereas the activator was copper acetate.

In terms of amounts, the fluorescent or phosphorescent compounds are preferably used in the phosphor materials at a level of from about 60-97% by weight, and more preferably from about 80-95% by weight. The activators are normally present in the phosphor materials in a level of from about 1-10% by weight9 and more preferably from about 3-8% by weight. The remaining preferred ingredients such as silicon oil, carbazole, zinc oxide, cadmium sulfide and anthracene are all present at a level of less than about 2% by weight. The conductivity layer 34, although preferably comprising polytechnic aluminum, can comprise or consist essentially of a large number of electrically conductive materials such as ferrous compounds.

In preferred forms, the phosphor material-bearing substrates of the invention are formed of flexible synthetic resin material. Thus, in the example given above, the base Mylar material has a thickness of2 mil. Generally, where a flexible substrate is desired, the material should have a thickness of from about 1-6 mil. Of course, the invention is also usable in the context of essentially rigid substrates if desired. Such substrates can be formed of virtually any dielectric material.

Another important feature of the invention resides in the use of a high-voltage, low-amperage power source. Generally speaking, the power source should deliver from about 500-1500 volts at 1500-3500 cycles per second with an amperage of from about 200-600 milliamps. More preferably, these values should be from about 800-1000 volts, from about 2000-2500 cycles per second, and an amperage of from about 350-500 milliamps.