WO1998030834A1

WO1998030834A1 - Solar marker light

Info

Publication number: WO1998030834A1
Application number: PCT/US1998/000423
Authority: WO
Inventors: Philip Albert Lerch
Original assignee: Alpan, Inc.
Priority date: 1997-01-08
Filing date: 1998-01-07
Publication date: 1998-07-16
Also published as: AU5959298A

Abstract

A solar-powered marker lamp (2) having extended light output per discharge and long bulb life. The solar power lamp (2) includes a photovoltaic cell (24), an electrical storage device (26) coupled to the photovoltaic cell (24), and a light-emitting diode LED assembly (10) coupled to the electrical storage device (26). Three LEDs (10) arranged around a central axis of the light are spaced 120 degrees apart. The LEDs (10) emit light in a complete arc of 360 degrees. The prismatic diffusing lens (4) surrounds the LED assembly (10) and provides homogenous, highly-diffused light. The diffusing lens (4) also allows a portion of the light to diffuse through to illuminate the area surrounding the marker light (2).

Description

SOLAR MARKER LIGHT

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to marker lights powered by solar energy. More particularly, the invention relates to solar-powered lights using solid state light assemblies and having extended life.

2. Description of the Related Art:

Exterior lighting is used widely to mark pathways, yards, parks, roadways, and other similar areas. Recently, in an effort to minimize expense and increase convenience, self-contained, solar-powered lights have been developed. The solar-powered lights convert daytime solar energy to electrical energy. The electrical energy is stored in batteries that power the lights during the night.

Various problems exist with the known solar- powered lights, including short bulb life, insufficient brightness, and inadequate power to keep the lights shining throughout the night.

Incandescent lamps have been used as a solution for outdoor lighting. The average life of an incandescent lamp, however, is only about 1,000 hours. Also, incandescent lamps draw a relatively large current and have high power consumption. Energy efficiency is very important ir. solar lighting as the energy obtained from commercially-available solar panels is only about 14% of the total energy. Further, the light emitted from incandescent lamps becomes yellow and dim as battery power drops.

More recently, solid-state devices have been used in certain lighting applications. These solid-state devices include, for example, light emitting diodes

(LEDs) and electroluminescent (EL) lamps. Solid-state lighting devices typically provide fairly low brightness, but have very low current requirements.

Accordingly, the need exists for a solar- powered lamp that supplies sufficient light throughout the night.

SUMMARY OF THE INVENTION

The present invention overcomes the disadvantages of the prior art by providing a solar- powered lamp having extended light output per discharge and long bulb life. The solar-powered lamp includes a photovoltaic cell, an electrical storage device coupled to the photovoltaic cell, and a light source, preferably a light-emitting diode (LED) assembly, coupled to the electrical storage device. The light source preferably emits light in a complete, circular arc of 360°.

A diffusing lens surrounds the light source to provide homogeneous, highly-diffused light. The diffusing lens preferably is made up of multiple, prismatic elements. Advantageously, the preferred prismatic diffusing lens reflects a portion of the visible light back toward the light assembly. The diffusing lens also allows a portion of the light to diffuse through the prismatic diffusing lens. According to a preferred embodiment, the lens is annular, and a reflector is mounted inside the annular diffusing lens. Preferably, the reflector has a focus, and the light source is placed at the focus of the reflector. The light source is disposed between the reflector and the diffusing lens, such that the reflector receives direct light from the light source, as well as the retro-reflected light from the prismatic diffusing lens. A circuit preferably is provided in order to turn the light on and off with changing lighting conditions. The preferred circuit does not require a solar cell to detect the presence of sunlight. Accordingly, manufacturing costs are reduced. According to a preferred embodiment, LED light sources provide approximately 50,000 hours of life. Also, the LEDs are very efficient, and provide a constant illumination level with small current consumption.

Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of a solar marking light according to the present invention.

Fig. 2 is a vertical cross-section of a solar marking light according to the present invention.

Fig. 3 is a side elevation of a prismatic diffusing lens for a solar marking light according to the present invention. Fig. 4 is a top view of the diffusing lens of Fig. 3.

Fig. 5 is a detailed view of a portion of Fig. 4. Fig. 6 is a schematic representation of light rays impinging upon a portion of the lens of Fig. 3.

Fig. 7 is a vertical cross-section of the diffusing lens of Fig. 3.

Fig. 8 is a detailed view of a portion of Fig. 7.

Fig. 9 is a detailed view of another portion of Fig. 7.

Fig. 10 is a vertical cross-section of an alternative diffusing lens according to the present invention.

Fig. 11 is a horizontal cross-section of a portion of the lens of Fig. 10.

Fig. 12 is a vertical cross-section of a portion of the lens of Fig. 10. Fig. 13 is a horizontal cross-section of a second alternative lens according to the present invention.

Fig. 14 is a partial detail view of the lens of Fig. 13. Fig. 15 is a schematic side elevation of a marker light according to the present invention.

Fig. 16 is a top view of a marker light according to the present invention.

Fig. 17 is an electrical schematic for a control circuit according to the present invention. Fig. 18 is an electrical schematic for an alternative control circuit according to the present invention.

Fig. 19 is an elevation of a solar light according to an alternative embodiment of the present invention.

Fig. 20 is a cut-away elevation of the solar light of Fig. 19.

Fig. 21 is a cut-away elevation showing an alternative arrangement of the solar light of Fig. 19.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially to Figs. 1 and 2, the general structure of a solar marker light 2 according to a preferred embodiment of the present invention is shown. The marker light 2 includes a prismatic diffusing lens 4 and a cap 6 disposed over the diffusing lens. The light is supported on a base 8.

Inside of diffusing lens 4, an LED 10 is supported on an extension 12. Second extension 14, and a third extension (not shown in the cutaway illustration of Fig. 2) are provided to receive second and third LED's. Upper and lower reflecting cones 16 and 18, respectively, are supported along the central axis of the marker light. Housed within cap 6 is a control circuit 20 disposed on a circuit board 22. A photovoltaic solar cell 24 and batteries 26, also housed within cap 6, are mutually connected via control circuit 20. A plastic cover 28 protects the electrical components and allows sunlight energy to pass through to solar cell 24. See also Fig. 16. Cap 6 extends outwardly circumferentially and protects the lower portions of the marker light from adverse weather conditions and the like. The lower surface 30 of the cap blocks light emitted by the light source, and reflects the light downward, for example, to light the ground along a path.

Base 8 includes a post 32 that extends downward (not shown) for installation into the ground. Alternatively, the extended post can be used for mounting to a light post or other object such as the side of a building. An upper surface 34 of base 8 is angled to direct light outward.

Referring to Figs. 3 through 15, diffusing lenses of the present invention will be described in greater detail. A sawtooth lens 35 according to a preferred embodiment has an outside surface 36 and an inside surface 38. Inside surface 38 is made up of a plurality of vertical ridges 40. Adjacent faces of vertical ridges 40 meet to form angles A, as shown in Fig. 5. Angle A preferably is between about 60° and about 120°, and most preferably is about 90° .

As shown schematically in Fig. 6, a portion of light rays 42 impinging on lens 4 strikes one of the faces and is reflected to the adjacent 90° face and subsequently retroreflected inwardly, preferably toward the LED, as reflected light rays 44. A portion of the impinging light rays 42 passes through lens 35 and emerges as light rays 46 to illuminate the area around the marker light. Impinging light rays 42 also can be made up of retroreflected light. The emerging light rays 46 are further diffused by the structure of the outside surface 36 of lens 35. Outside surface 36 includes a plurality of horizontal ridges 48, shown in greater detail in Figs. 8 and 9. Adjacent surfaces of horizontal ridges 48 meet to form angles B, as shown in Fig. 9. Angle B preferably is between about 60° and about 120°, most preferably about 90°.

Alternatively, the inner and outer ridges can be formed as a series .of curved ridges, such as the sine wave configuration shown in Figs. 10 through 12, or the half-sine wave configuration illustrated in Figs. 13 and 14, for example. Referring to Figs. 10 through 12, a diffusing lens 50 according to an alternative embodiment of the present invention will be described in greater detail. Diffusing lens 50 has an inner surface 52 and an outer surface 54. Inner surface 52 is made up of a plurality of vertical ridges 56. As shown in horizontal cross-section in Fig. 11, ridges 56 have a sine wave configuration. A portion of the light rays impinging on one of the surfaces is retroreflected in a manner similar to that shown and explained above in connection with Fig. 6. Similarly, a portion of the impinging light rays pass through lens 50 and emerges as light rays to illuminate the area around the marker light.

The emerging light rays are further diffused by the structure of the outside surface 54 of lens 50.

Outside surface 54 includes a plurality of horizontal ridges 58, formed in a sine-wave configuration, as shown in detail in the vertical, cross-sectional view of Fig. 12. Referring to Figs. 13 and 14, a diffusing lens 60 according to a second alternative embodiment of the present invention will be described in greater detail. Half sine-wave lens 60 has an inner surface 62 and an outer surface 64. Inner surface 62 is made up of a plurality of vertical ridges 66, shown in horizontal cross-section in Fig. 13. As shown in more detail in Fig. 14, ridges 66 have a half sine-wave configuration. A portion of the light rays impinging on the inner surface 62 is retroreflected in a manner similar to that shown and explained above in connection with Fig. 6.

Similarly, a portion of the impinging light rays passes through lens 50 and emerges as light rays to illuminate the area around the marker light.

The emerging light rays may be further diffused by the structure of the outside surface 64 of lens 60.

Outside surface 64 can include a plurality of horizontal ridges formed in a sawtooth, sine-wave, or half sine-wave configuration, in a manner similar to the embodiments of the diffusing lenses set forth above. Referring to Fig. 15, conical reflectors 16 and

18 are arranged so as to form a focus 70 where LEDs 10 are positioned. As shown schematically in Fig. 15, light from LED 10 reflects off of cone reflectors 16, 18 and is directed in rays substantially outward toward and through lens 4 as described more fully above.

Referring to Figs. 17 and 18, control circuits for the marker light of the present invention are shown. Control circuit 20 of Fig. 17 includes a first resistor 72 coupled in parallel with photovoltaic solar cell 24 and coupled to the base of a transistor 74. A second resistor 76 is coupled in series with LED 10, the series assembly being in parallel with the first resistor 72, and coupled to the source of transistor 74. The drain of transistor 74 is coupled to one side of battery 26, and to the series assembly of the second resistor 76 and LED 10. A Schottky diode 80 is connected between the drain of transistor 74, and the solar cell 24.

Control circuit 20 provides day/night operation without the need for a light sensor as follows: When the energy output of solar cell 24 falls below a certain level, battery 26 begins to discharge, turning on transistor 74 and illuminating LED 10.

Control circuit 82 is similar to control circuit 20, and has been numbered accordingly, except that a light sensor 84 is used to detect when the LED should be illuminated, at dusk, for example. When light sensor 84 detects a lower light level, transistor 74 turns on, allowing current to flow from battery 26 through LED 10.

Fig. 19 illustrates an alternative embodiment of a solar light according to the present invention. Figs. 20 and 21 illustrate alternative internal arrangements of the marker light shown in Fig. 19. Solar marker light 92 includes a prismatic diffusing lens 94 and a cap 96 disposed over the diffusing lens. The light is supported on a base 98.

Referring to Figs. 20 and 21, inside of diffusing lens 94 a light source 100 is supported on an extension 102. Another light source 104 is controlled by a motion detector 106. Light source 104 preferably is a high intensity light source such as a halogen lamp. High intensity light source 104 and motion detector 106 preferably are connected to a timing circuit so that the high-intensity light source returns to a normally-off condition after a predetermined time period, 30 seconds for example, in the absence any detected motion. Housed within cap 96 is a control circuit similar to circuit 20 described above. Similarly, a photovoltaic solar cell and batteries also are housed within cap 96, and are mutually connected via the control circuit. A plastic cover protects the electrical components and allows sunlight energy to be directed onto the solar cell. Cap 96 extends outwardly circumferentially and protects the lower portions of the marker light from adverse weather conditions and the like. The lower surface of the cap serves to block light emitted by the light source, and reflects the light downward to light the ground along a path, for example.

Fig. 21 illustrates solar marker light 92 with an alternative light source arrangement, in which similar components have been numbered as they were in Figs. 19 and 20. Light source 90 is a solid-state light source such as an LED of an EL lamp positioned on platform 92 above base 98.

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. Therefore, the present invention is to be limited not by the specific disclosure herein, but only by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A solar powered lamp providing highly diffused and extended lighting per discharge, the solar powered lamp comprising: a photovoltaic cell receiving sunlight and generating electrical energy; an electrical storage device coupled to the photovoltaic cell, the electrical energy generated by the photovoltaic cell charging the electrical storage device, the electrical storage device providing low voltage direct current during discharge; a light assembly coupled to the electrical storage device, the light assembly generating visible light when provided with the low voltage direct current; and a prismatic lens surrounding the light assembly and providing homogeneous, highly-diffused light from the light assembly.

2. The solar powered light of claim 1, wherein the prismatic lens reflects a portion of the visible light back toward the light assembly.

3. The solar powered light of claim 1, further comprising a reflector mounted within the lens.

4. The solar powered light of claim 3, wherein the reflector has a focus, and the light assembly is disposed within the focus, the reflector receiving light from the light assembly and light from the portion of the light reflected by the prismatic lens.

5. The solar powered light of claim 3, wherein the reflector comprises a cone having a parabolic cross-section.

6. The solar powered light of claim 3, wherein the reflector comprises a cone having a triangular cross-section.

7. The solar powered light of claim 3 , wherein the reflector has a central axis, and the light assembly comprises a plurality of lights spaced at equal angular intervals around the central axis of the reflector.

8. The solar powered light of claim 1, wherein the light assembly comprises at least one light selected from the group consisting of light emitting diodes, incandescent bulbs, fluorescent tubes, and electroluminescent lamps.

9. The solar powered light of claim 8, wherein the light assembly comprises LED's, each LED emitting light in a 360┬░ direction.

10. The solar powered light of claim 1, wherein the prismatic lens has a surface and a central axis, the surface comprising a plurality of ridges extending substantially parallel to the central axis.

11. The solar powered light of claim 10, wherein the ridges form a sawtooth cross-section of the surface of the lens.

12. The solar powered light of claim 10, wherein the ridges form a sine wave cross-section of the surface of the lens.

13. The solar powered light of claim 10, wherein the ridges form a half-sine wave cross-section of the surface of the lens.

14. The solar powered light of claim 10, wherein the surface is an internal surface.

15. The solar powered light of claim 10, wherein a surface of each ridge forms an angle with an adjacent surface of an adjacent ridge.

16. The solar powered light of claim 15, wherein the angle is between about 60┬░ and about 120┬░.

17. The solar powered light of claim 16, wherein the angle is about 90┬░.

18. The solar powered light of claim 1, wherein the prismatic lens is hollow and annular with a surface, the surface comprising a plurality of annular ridges, the ridges forming a cross-section of the surface of the lens.

19. The solar powered light of claim 18, wherein the surface is an external surface.

20. The solar powered light of claim 18, wherein the ridges form a sine wave cross-section of the surface of the lens.

21. The solar powered light of claim 18, wherein the ridges form a half-sine wave cross-section of the surface of the lens.

22. The solar powered light of claim 18, wherein a surface of each annular ridge forms an angle with an adjacent surface of an adjacent ridge.

23. The solar powered light of claim 22, wherein the angle is between about 60┬░ and about 120┬░.

24. The solar powered light of claim 23, wherein the angle is about 90┬░.

25. The solar powered light of claim 1, wherein the prismatic lens has a central axis, and the light assembly comprises a plurality of lights spaced at equal angular intervals around the central axis of the prismatic lens.

26. The solar powered light of claim 1, further comprising a control circuit coupled to the photovoltaic cell, the electrical storage device, and the light assembly, the control circuit providing the low voltage direct current from the electrical storage device to the light assembly when the photovoltaic cell generates less than a predetermined amount of electrical energy.

27. The solar powered light of claim 26, wherein the control circuit is configured to activate the light assembly at dusk without the use of a photo sensor.

28. The solar powered light of claim 1, further comprising a control circuit coupled to the photovoltaic cell, the electrical storage device, and the light assembly, the control circuit having a photo sensor and providing the low voltage direct current from the electrical storage device to the light assembly when the photo sensor detects a predetermined amount of light.

29. The solar powered lamp of claim 1, further comprising a high intensity light source for providing periods of during which high intensity light is emitted by the lamp.

30. The solar powered lamp of claim 29, further comprising a timing circuit for limiting a time duration of the periods of high intensity light.

31. The solar powered lamp of claim 29, further comprising a motion detector for activating the high intensity light source in response to detected motion.

32. A solar powered lamp providing highly diffused and extended lighting per discharge, the solar powered lamp comprising: a photovoltaic cell receiving sunlight and generating electrical energy; an electrical storage device coupled to the photovoltaic cell, the electrical energy generated by the photovoltaic cell charging the electrical storage device, the electrical storage device providing low voltage direct current during discharge; a patterned, annular prismatic lens; and a light source disposed within the prismatic lens, the light source being coupled to the electrical storage device, the light source providing light visible through the prismatic when supplied with the low voltage direct current.

33. The solar powered lamp of claim 32, wherein the annular prismatic lens has a central axis, and the light source provides the light along the axis of the lens.

34. The solar powered lamp of claim 32, further comprising a high intensity light source for providing periods of during which high intensity light is emitted by the lamp.

35. The solar powered lamp of claim 32, further comprising a timing circuit for limiting a time duration of the periods of high intensity light.

36. The solar powered lamp of claim 32, further comprising a motion detector for activating the high intensity light source in response to detected motion.