HK1037227B - Method and apparatus for light transmission - Google Patents

Description

Device for optical transmission

Technical Field

The invention disclosed herein relates to the field of light transmission, and more particularly to a self-supporting light-guiding medium and the use of the medium as a light-transmitting material, for use in reflective tapes, protective clothing, safety helmets, and the like, for safety or similar considerations.

Background

In recent years, comfort and health have become more important in the united states and many other countries, and it has become more common for individuals and groups to run, roam or walk on streets, sidewalks, parks and runways in cities and villages. Due to time constraints, many people run in the dusk or night curtain before or after work. The street occupied by the runner is very dark because there is no sidewalk or because it is out of repair, or the night has come and the light is darkest. Street lights are typically located at the corners of streets with long streets having large spaces without lights and therefore cannot always be seen clearly by runners. Other factors affecting visibility are the non-reflective dark clothing worn by many runners, and therefore not readily visible to the vehicle driver when the runner is on the street.

Recent attempts to make runners easily visible include having runners wear white or light colored garments that can be more easily seen by light from running vehicles, or providing reflective bands on the front and back of sports apparel such as jackets that can capture and reflect light from running vehicles. Even with these measures, there are still a number of accidents involving runners and moving vehicles, which should otherwise be avoided. Obviously, runners or walkers are subjected to more serious injuries when they collide with a running vehicle, and the number of deaths caused by the runners being hit by the running vehicle has increased in recent years.

To overcome these problems and the resulting injuries and deaths and losses involved, efforts have been made to provide devices that make runners more visible in dark or less visible environments. One common device is a reflective vest to be worn on the body of a runner, having reflective bands positioned horizontally and/or vertically on the vest, the bands to reflect light from the running vehicle; however, if the driver does not turn on the lights in the dark, the protective garment becomes theoretically effective only. In a similar manner, reflective belts worn by runners are ineffective unless he or she is running where the light from the street lights can impinge on the reflective material or the vehicle's light can be directed at the belt.

Recently, various types of individually powered light guides are worn by runners or walkers in an attempt to produce greater visibility in the dusk or darkness. Such light guides include devices attached to one or more limbs of the participant, such as a leg light attached to one limb of the runner and having a self-contained battery pack, a light and a reflector to provide continuous light. Other types utilize a flashing light with a diffuser lens to emit light. In addition, a flashing airplane strobe light is also feasible, which can be clipped to a strap or garment to provide a higher visibility light source, making it more visible in the dark. However, these devices are limited in the angle at which the light source intensity or light can be viewed, and most devices are not visible above 160 to 180 degrees. Thus, if the vehicle approaches the runner at an angle invisible to the device, for example from the side, the driver cannot see the runner until a collision is unavoidable. To overcome this, multiple lights may be utilized, but this approach adds additional weight and discomfort to the runner. In addition, many retroreflective tapes use electroluminescent materials with relatively dark light sources, providing only limited visibility.

The present invention overcomes the above-described limitations and disadvantages of known lighting devices by providing a relatively high intensity light that can be viewed from a great distance and that can be incorporated into a reflective belt or protective garment that is comfortably worn by a runner and that allows the runner to be seen at any angle by a passing vehicle driver.

Disclosure of Invention

The present invention relates to methods and devices for light transmission that more efficiently provide light transmission devices, such as retroreflective tapes and safety shields, with higher intensity than those currently utilized in safety devices. The device comprises a light source such as a flashlight bulb, Light Emitting Diode (LED) or the like and a self-supporting light guiding medium which is one or more elongated bodies of a flexible thermoplastic material, typically a hot melt glue. The hot melt adhesive material can be formed in a variety of lengths and cross-sectional shapes and varying degrees of transparency. The material has a particularly high flexibility and transparency, so that when the light source is positioned at the end of the elongated body, light is transmitted along the length of the elongated body with a relatively high intensity, providing a high visibility compared to electroluminescent materials.

In view of this, the present invention provides a portable reflective belt wearable by a user, the portable reflective belt comprising: a belt formed of flexible material and having a length around the waist of a user, a battery pack and circuitry mounted on the belt, the belt providing an elongated envelope containing a plurality of light sources distributed along the length of the belt, characterized in that: the enclosing structure also houses at least one elongated light guide body which positions the light sources along its length and transmits light along the length of the light guide body which is formed of a clear hot melt adhesive thermoplastic material having superior light guiding properties.

The present invention also includes a light emitting device that, because of its high flexibility, can be incorporated into a reflective belt and/or a protective garment that is worn over the body of a runner or other user and that conforms to the contours of the body without discomfort to the wearer. One method of using the hot melt adhesive is to utilize hot melt adhesive rods in a length generally aligned end-to-end along an axis with the light-reflecting diodes sandwiched between the rods with a pair of strips of electrically conductive fabric material parallel to the rods and having connections from the fabric to the diodes. The structure may be formed in a variety of ways, such as extrusion, injection molding, and the like.

The invention also includes the provision of a light emitting band formed from a strip of "Velcro" material wherein the strip with loops is opaque and reflective, the strip with hooks is of a transparent material allowing light transmission, the light guide and diodes are positioned centrally between the strips, the strips surrounding the light guide and being connected together by a hook and loop structure of "Velcro" material.

Drawings

FIG. 1 is a silhouette of a wearer of a retroreflective tape, the tape of the present invention encircling the waist of the person.

FIG. 2 is a front view of one embodiment of a light source for use in the reflective band.

Fig. 3 is a perspective view of a reflective tape housing a light source.

Fig. 4 is a vertical sectional view taken along line 4-4 in fig. 3.

Fig. 5 is a schematic diagram of an electronic circuit for powering the diodes or other light sources of the belt.

Fig. 6 is a perspective view of a second embodiment of a reflective tape surrounding a diode and a luminaire with retroreflective strips.

Fig. 7 is a plan view of the light source, with the front transparent portion of the band omitted.

Fig. 8 is a vertical sectional view taken along line 8-8 in fig. 6.

Fig. 9 is a vertical sectional view taken along line 9-9 in fig. 6.

FIG. 10 is a front view of a broken away portion of a third embodiment of a strap using a different arrangement of diodes and with a light guide.

Fig. 11 is an enlarged perspective view with a cutaway showing another version of the light with the diodes embedded in a hot melt adhesive attached to the light.

Fig. 12 is an enlarged cross-sectional view of another version of a luminaire similar to that shown in fig. 11.

FIG. 13 is a front elevation view in broken away of a fourth embodiment of retroreflective tape utilizing "Velcro" fastener type material.

Fig. 14 is an elevational cross-sectional view of the strap taken along line 14-14 of fig. 13.

FIG. 15 is a front view of a person wearing a reflective or safety vest incorporating a light emitting diode and a light guide in accordance with the present invention.

Fig. 16 is a perspective view of the protective garment of fig. 15.

Detailed Description

Referring specifically to the contents of the drawings, which show illustrative embodiments of the present invention, FIG. 1 shows a person 10, a child or adult, who will use the lighting strip 11 of the present invention. The strap 11 is shown encircling the waist of a wearer, who may be a child playing in the dark, who wishes to be seen by a passing vehicle driver, or an adult running or walking in the dark. Such a belt is particularly suitable for police officers directing traffic or fire fighters on standby during a night fire.

The belt 11 is formed of an elongate base belt 12 and an elongate transparent front belt 13, the base belt 12 being of an opaque, light-reflecting material and the front belt 13 being of a material which transmits light and can be viewed by others. Located within the tube or housing formed by the base and transparent strips of material is a light transmission device 15, the device 15 comprising one or more elongated bodies 16 of substantially transparent or clear thermoplastic material, in the form of a hot melt adhesive material as is well known, which comprises a gel consisting essentially of: ethylene vinyl acetate, manufactured by h.b. fuller of saint paul, minnesota, under material designation 110; low density polyethylene, made by the Ad-Tech plastics systems adhesive technology division, and labeled "Crafty" hot melt adhesive, which is a registered trademark of Ad-Tech plastics systems; a polypropylene thermoplastic or polyamide gel manufactured by HysolEngineering Adhesives of Seabrook, N.H., under the designation #7820 Hysol. All of the above-identified materials have strong flexibility and high clarity or transparency. Fuller ethylene vinyl acetate is in the form of pellets, pads and medium length rods. These rods have a high flexibility, the transparency being determined by heating the material to 300 to 350 degrees and rapidly cooling the material.

To provide a source of light for the rod or other elongate body, a plurality of light emitting diodes 17 are positioned at intervals in the band 11 between the ends of the axial extensions 16. Also parallel to the rod are two strips 18, 19 of conductive fabric, such as "Flecton", a registered trademark of Monsanto. The fabric is a nickel or nickel/copper mesh material that conducts current from a power source (see fig. 5) to the diodes through connecting wires 21.

The elongated body 16 is of an appropriate length depending on the degree of light transmission required, the diode being sandwiched between and located between the elongated strips of material 12, 13 by positioning the elongated body, the diode and the conductive fabric being located between the strips, the strips being sewn together at their outer edges 22; the plastic material, the conductive fabric and the diode are fed into an extruder and extruded with the thermoplastic material to form the desired cross-sectional shape, the diode and the conductive means are embedded in the plastic, and the plastic acts as an electrical insulator for the conductive fabric and the diode; alternatively, the fabric and diode may be placed in a suitable mold and either injected with a hot melt adhesive thermoplastic material or the mold is moved around the light guide and cooled rapidly to provide maximum transparency.

The elongated body 16 is an ethylene vinyl acetate thermoplastic material of suitable length and the light transmission source 17 may be any light emitting source, visible or invisible, such as near infrared light or infrared light, etc.; more common lighting means include relatively high intensity flashlight bulbs, light emitting diodes, halogen lamps or lasers. The conductive material may be a conductive fabric as shown or other suitable conductive textile, polymer, liquid, gas, metal, or combination of these materials to conduct electrical energy to the electrical input of the light emitting source. The light-conducting material serves as electrical insulation for the device.

FIG. 5 is a schematic diagram of a suitable circuit for powering the tape of the present invention having a 3.0 volt DC battery pack 22 in series with a switch 23, the battery pack spanning terminals 4 and 5 of a 3909LED flasher chip 24, the terminal 4 leading to a common ground 25. A first transistor 26 has a base 27 connected to terminal 2 of the chip and an emitter 28 connected to terminal 6. A collector 29 of the transistor is connected to a base 32 of a second transistor 31, the second transistor 31 having an emitter 33 connected to the common ground 25 and a collector 34 leading to one side 36 of the plurality of diodes 17; the opposite side 37 of the diode is connected to the battery pack 22, the diodes being connected in parallel. Also, a capacitor 38 is connected between terminals 2 and 8 of the chip.

A second embodiment of a retroreflective tape 41 is shown in fig. 6-9, wherein the tape is formed from a retroreflective material "Reflexite," which is a registered trademark of Reflexite corporation. The tape includes a white backing or sliver 42 and a front sliver 43, the sliver 42 reflecting light forward, the sliver 43 being a vinyl lens to magnify the light. The elongated body 44 and the diode 45 and their connections are in a tube or housing formed by the elongated strips 43 and 44, and a circuit board 46 houses a circuit as shown in fig. 5, to which a battery pack 47 provides power. The vinyl lens scatters light from the stem portion more uniformly along the entire length of the stem, so that the light is emitted a distance whether it is continuously or blinkingly emitted.

A third embodiment of a retro-reflective band 51 is shown in figure 10, in which the band is formed by a base band 52 and a front clear band 53, and one or more elongate light guides 54 are positioned between a pair of light emitting diodes 55 and 56 facing in opposite directions to direct light from the diodes along the light guides 54. In this embodiment, diodes 55 and 56 may be of different colors or flash at different frequencies, thus providing a multi-colored flash band to the wearer.

As shown in fig. 11, the elongated light guide body 61 has an irregular shape, and the circular top surface 62 and the concave lower surface 63 are formed of hot-melt adhesive plastic. Longitudinally spaced diodes 64 are received in a central recess 63 of light guide 61; the diode is embedded in a hot melt adhesive 65 formed around the diode and filled into the groove 63; the diodes are positioned to direct light along the length of the light guide 61. Suitable connections 66 for supplying electrical energy to the diodes are also embedded in the hot melt glue 65.

Fig. 12 shows another elongated light emitter 67 similar to that shown in fig. 11, having an irregular shape with a rounded top surface 68 and a recess 69 on the lower surface for receiving a longitudinally spaced diode 71, the diode 71 being in an applied hot melt adhesive 72 and positioned to direct light along the emitter. Formed on the lower surface is some type of light reflecting means, such as light reflecting microprisms, which will enhance the light guiding properties of the emitter. Both the light emitters 61 and 67 may be extruded from a suitable extruder from which the diodes and hot melt adhesive body are applied to the light emitters as they are discharged. Moreover, suitable rollers or other components may also be used to provide the prismatic surface of the emitter.

A fourth embodiment of retroreflective tape 81 is shown in fig. 13 and 14 wherein an elongated strip of clear nylon, polypropylene, polyethylene or polyester or similar material having a hook and loop type material, such as those brands known by the trade mark "Velcro" from Velcro, inc, the trade mark "Cosmolon" from YKK, etc., may be used to form a band or housing that houses light guide 87 and diode 88. The band is formed of a backing strip 82 of "Velcro" type material containing loops 83 which is white or light colored to reflect light forwardly from the stem portion. A front clear band 84 of "Velcro" material contains a resilient hook material 85. The light guide and light source are sandwiched between "Velcro" strips of material having loops and hooks facing each other so that the light guide, light emitter and connecting material are in the tube formed by the "Velcro" strips, the hooks and loops connecting the strips together at the edges 86 to form a belt.

Fig. 15 and 16 illustrate the use of suitable light sources and reflective materials in a safety vest 91, the vest 91 being worn by workers in a variety of industries, including workers working on railways, road construction, and the like. Such protective clothing can also be used with the aid of a cross section without affecting the light transmission properties of the material; the light guide may also be connected at its ends, within which the light transmitted is only minimally lost. Light can pass through the material at any angle, not just from the end of the light guide. Thus, at the light guide, where the light rays are emitted in a direction perpendicular to its axis or at any angle relative to the axis, the light rays will pass through the material. Materials that can serve as substrates for ethylene vinyl acetate plastics are low density polyethylene, polypropylene, copolyester plastics manufactured by Eastman chemical company under the designation "spectra", polyamide thermoplastics, manufactured by Hysol Engineering Adhesives under the designation #7820 Hysol, or combinations thereof, although these materials do not necessarily have the higher flexibility as does ethylene vinyl acetate plastics. For example, the "spectra" material is a relatively rigid plastic that has a high degree of optical clarity, but is more rigid than an ethylene-vinyl acetate thermoplastic. When driven by a light emitting source, the light guiding material emits light in all directions from all planes inside and outside. Furthermore, when the device is used in a flammable environment, the thermoplastic hot melt adhesive may be suitably flame retardant to prevent fire or explosion.

In addition to hot melt adhesives, other suitable materials that are transparent sealants include the following items that can be applied as transparent gels to a weld of appropriate length. Such products include "Liquid Seal", a trademark of Macco Adhesives division of Glidden corporation; "Shoe Goo" and "Shoe Goo II", registered trademarks of Electroproducts, Inc.; and "Amazing Goop" colloid, a trademark of the company electronic Products. The latter product is a gel formed primarily from propyl acetate and petroleum distillates. Each product was applied as a gel and then cured to form a flexible weld of sealant that could be used for light transmission.

The intensity of the light output can be increased by selectively scoring the outer plane of the light guide material, or the light intensity can also be increased by selectively lining the plane of the light guide material with a suitable light reflecting material. Dyes or colorants may be added to the photoconductive medium to alter the effect produced. Furthermore, the visible light output of the red, green and blue leds may be combined with a light guide in a belt or vest, with the light traveling through the core or along the surface of the light guiding medium to obtain a sixty-four array of color spectra. The light guide may also be layered, bundled or woven in various combinations to achieve desired light output characteristics.

Although the circuit shown in fig. 5 is a 3.0 volt battery pack for powering the light source, other possible circuits with different chips with other power sources, which may be dc or ac, where ac may be converted to dc voltage of desired voltage and current, may be utilized.

Claims (23)

1. A portable retro-reflective band wearable by a user, the portable retro-reflective band comprising: a belt formed of a flexible material and having a length to encircle a user's waist, a battery pack, and circuitry mounted on said belt, said belt providing an elongated envelope containing a plurality of light sources distributed along the length of the belt, characterized in that:

the enclosing structure also houses at least one elongated light guide body which positions the light sources along its length and transmits light along the length of the light guide body, which is formed of a transparent hot melt adhesive thermoplastic material having superior light guiding properties.

2. The retroreflective tape of claim 1, wherein: the light source is a halogen lamp.

3. The retroreflective tape of claim 1, wherein: the tape comprises a bottom layer of light reflecting material and a front surface layer of transparent plastic material.

4. The retroreflective tape of claim 1, wherein: the light source is powered by a battery powered circuit that provides a flashing capability through the light guide.

5. The retroreflective tape of claim 1, wherein: the band is formed of a retroreflective material and includes a white base layer and a front vinyl lens through which light from the light guide is scattered.

6. The retroreflective tape of claim 1, wherein: the band is formed from a pair of strips of "Velcro" clear nylon, polypropylene, polyethylene or polyester with loops and hooks facing the material surface to wrap the light guide and light source along a central portion and engage each other along edges to form a housing.

7. The retroreflective tape of claim 6, wherein: the strip with the ring is made of a light-reflecting material, the strip with the hook is made of a transparent material, and the light-reflecting material and the transparent material form a shell for the light guide device.

8. The retroreflective tape of claim 1, wherein: the light-directing plastic has one or more dyes or colorants affixed therein.

9. The retroreflective tape of claim 1, wherein: the light guide has a light source combining red, green and blue light emitting diodes to obtain a sixty-four array color spectrum.

10. The retroreflective tape of claim 1, wherein: the light guide is combined with other materials in layers, weaves or bundles to obtain the desired light characteristics.

11. The retroreflective tape of claim 1, wherein: one light emitting diode at each end of the light guide, the pair of light emitting diodes facing opposite ends of the light guide.

12. The retroreflective tape of claim 1, wherein: the elongated body has diodes bonded or encapsulated therein at intervals along its length.

13. The retroreflective tape of claim 12, wherein: the elongated body has an outer shape with a rounded top surface and a recess formed in the bottom surface, the diode and the hot melt adhesive material being inserted into the recess at spaced intervals along the elongated body.

14. The retroreflective tape of claim 1, wherein: the diode is enclosed in the hot melt adhesive, and a reflective microprism is formed on the lower surface of the elongated body.

15. A safety vest to be worn by a person on or near a roadway or road desired to be seen, comprising a vest of coloured and light reflecting material having front and rear portions attached over the shoulders, means connecting said front and rear portions by side attachment means, and a light guiding strip on either the front or rear portion or both, each said light guiding strip having an elongate surrounding shell of material and containing one or more light guiding bodies of hot melt adhesive thermoplastic material and one or more light sources at the ends of the light guiding bodies, and a battery pack and circuitry for flashing the light sources.

16. The safety protective garment of claim 15, wherein: each light guide strip is a separate unit with its own battery pack, circuitry and light guide.

17. An apparatus comprising at least one light source and at least one part of a flexible and substantially transparent hot melt adhesive thermoplastic material, characterized in that: the part is capable of transmitting and emitting light, and the light source is adjacent to the part.

18. The apparatus of claim 17, wherein: the light source is embedded in the part.

19. The apparatus of claim 17, wherein: the hot melt adhesive thermoplastic material is selected from ethylene vinyl acetate, low density polyethylene, polypropylene and polyamide.

20. Comprising at least one light source and at least one elongated element of hot melt adhesive thermoplastic material having a longitudinal axis, the light source being positioned along the longitudinal axis of the element.

21. A safety belt comprising an elongated and substantially transparent hot melt adhesive thermoplastic material having a rounded top surface and a lower surface in which a groove is formed; a light reflecting structure formed in the lower surface; and a light source embedded in the hot melt adhesive material and positioned in the recess at spaced intervals along the elongated body.

22. The harness of claim 21 wherein: the light reflecting structure is a microprism.

23. The seat belt of claim 1, wherein: the base band includes a retroreflective material and the safety band includes a front skin of transparent plastic material positioned over the light source and the light guide.