WO2015163770A1

WO2015163770A1 - Solid state light

Info

Publication number: WO2015163770A1
Application number: PCT/NZ2015/000031
Authority: WO
Inventors: Patrick John Martin
Original assignee: Solar Bright Limited
Priority date: 2014-04-24
Filing date: 2015-04-23
Publication date: 2015-10-29
Also published as: NZ624126A; AU2014101189A4; CN204176385U

Abstract

Described herein is a solid state light. More particularly, a solid state light in the form of a tube that may be used to retrofit to existing fluorescent light fittings or instead used in new light fittings. The solid state light comprises a pin connection at the tube fitting end that mates with the fluorescent tube light fitting.

Description

SOLID STATE LIGHT

TECHNICAL FIELD

Described herein is a solid state light. The application relates to a solid state light in the form of a tube that may be used to retrofit to existing fluorescent light fittings or instead used in new light fittings.

BACKGROUND ART

Considerable prior art in the area of solid state lights including those using light emitting diodes (LEDs) exists. One particular application of this technology is in retrofit of existing fluorescent tubes that have been on the market for well over 50 years. LED technology offers considerable advantages of fluorescent lights and for almost 10 years now, a growing industry has developed specifically around replacement of fluorescent lighting with LED lighting.

Existing LED lights are clearly meeting a market need and offer considerable benefits.

However, the light is highly directional meaning the quality of light can be variable compared with other forms of light. In addition, existing LED tubes often have a large number of LEDs in order to generate a comparable level of light to fluorescent tubes - hundreds of bulbs in fact for a standard 4 foot long tube. This high number of bulbs raises the issue of heat dissipation since the heat generated by this large number of diodes needs to be removed. Also, the large number of bulbs requires the use of a higher input of power and the need to power both ends of the tube using two or more drivers in order to have enough power. Drivers are an expensive part of the LED tube and a part that is often the first to fail, hence removal of one or both drivers may have a significant impact on the tube cost and longevity.

The lighting device described in EP2104798 is a product designed to improve and enhance the quality of light from LEDs. As noted above, standard LED tubes provide a light that is highly directional and not particularly diffuse and uniform in nature. EP2104798 houses the LED lights in an acrylic tube and uses reflective strips on the ends of the tube and back of the tube to reflect and direct the light from the tube. The resulting quality of light is better and more diffuse than standard LED tubes. An additional benefit is that because the light is reflected and enhanced in the acrylic tube, dramatically fewer LED lights are needed to achieve the same level of light output. EP2104798 does not however readily present the lighting module into a form suitable for retrofitting into existing fluorescent tube fittings. Heat dissipation is also only somewhat addressed.

WO 2008/078077 discloses the use of a solid rod of transparent material having radial bores containing LEDs arranged to emit light parallel to the axis of the rod with a reflector and opaque backing (heat sink). As above, WO 2008/078077 does not however readily allow a form suitable for retrofitting into existing fluorescent tube fittings. As should be appreciated from the above, there is a need to provide a product that is able to be fitted to existing fluorescent light fittings with minimal work needed or at least to provide the public with a choice.

Further aspects and advantages of the solid state light will become apparent from the ensuing description that is given by way of example only.

SUMMARY

Described herein is a solid state light in the form of a tube that may be used to retrofit to existing fluorescent light fittings or instead used in new light fittings.

In a first aspect there is provided a solid state light able to be fitted to a standard fluorescent tube light fitting, the light having a substantially tubular shape comprising:

(a) a solid transparent rod of semi-circular to circular cross-section having a central longitudinal axis and being made of a material that sustains total internal reflection of light;

(b) a reflector to reflect light from the rod, wherein the reflector is a diffusely reflective strip extending along the rod at or near the surface thereof;

(c) a plurality of radial bores spaced apart along the length of the rod;

(d) a plurality of powered LED light sources disposed within each bore, the LEDs disposed back to back so that light emitted from each LED is directed generally parallel to the central longitudinal axis of the body and generally normal to the axis of the bores, whereby light is substantially totally internally reflected within the rod;

(e) an electric circuit coupling the plurality of LED lights to at least one end connection of the tube, the end connection being able to electrically couple with an existing fluorescent tube fitting; and

(f) an opaque backing, the backing aligned behind or about the reflector.

In a second aspect there is provided a standard fluorescent tube light fitting fitted with the solid state light defined above.

Advantages of the above, when compared to some existing LED lights include better light quality, light that is more diffuse, less heat generated, better dissipation of heat that is generated, and use of fewer LED lights to achieve the same level of light output. The solid transparent rod used in the above device may also be formed of a substance that assists with heat dissipation from the LEDs, such as acrylic, thereby further mitigating heat dissipation issues. Another advantage includes the ability to only use one driver that may be beneficial in terms of both cost of manufacture and lower failure rate than an equivalent light with two or more drivers. Other advantages include avoiding the negative aspects of fluorescence lighting such as: higher wattage requirement; greater energy consumption; greater fragility; emission of UV and infrared light; inability to dim; slow warm-up; and problems associated with mercury in bulbs and disposal of such bulbs. A particular advantage of the device described herein may be that the above advantages are obtained while using existing fittings for fluorescence lights, thereby avoiding the expense and inconvenience associated with installing new light fittings.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the solid state light will become apparent from the following description that is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 is a schematic cross section of a solid state light of the present invention; and Figure 2 is a schematic perspective view of a solid state light of the present invention;

DETAILED DESCRIPTION

As noted above, the application broadly relates to a solid state light in the form of a tube that may be used to retrofit existing fluorescent light fittings or instead used in new light fittings.

The term 'LED' and grammatical variations thereof refers to a light-emitting diode, a semiconductor light source. LEDs operate over a long lifetime with low energy

consumption. LEDs are available in a variety of colours, any of which may be used for the present application.

For the purpose of this specification the term 'comprise' and grammatical variations thereof shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements.

The term 'about' or 'approximately' and grammatical variations thereof mean a quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a

reference quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length.

The term 'substantially' or grammatical variations thereof refers to at least about 50%, for example 75%, 85%, 95% or 98%.

In a first aspect, there is provided a solid state light able to be fitted to a standard fluorescent tube light fitting, the light having a substantially tubular shape comprising:

a reflector to reflect light from the rod, wherein the reflector is a diffusely reflective strip extending along the rod at or near the surface thereof;

a plurality of radial bores spaced apart along the length of the rod;

(d) a plurality of powered LED light sources disposed within each bore, the LEDs

disposed back to back so that light emitted from each LED is directed parallel to the central longitudinal axis of the body and generally normal to the axis of the bores, whereby light is substantially totally internally reflected within the rod;

(f) an opaque backing, the backing aligned behind or about the reflector.

The solid transparent rod may be formed by casting or by extrusion. It may be manufactured out of any one of a plurality of materials, or combination thereof, but the rod itself should be such that it sustains total internal reflection of the light emitted by the LEDs. The rod may be formed of an acrylic material.

The rod may take any dimension and/or shape that sustains total internal reflection. The rod may be a straight rod. The rod may be curved or take any shape that existing fluorescent lights take, as long as that shape can sustain total internal reflection.

The reflector may be formed of any material suitable to diffusely reflect light emitted from the LEDs. It may be integrally formed with the rod, it may be bonded to the exterior of the rod, or it may be situated along the rod either directly contacting or separate its surface, as long as it is located such that it can reflect light emitted from the rod. The width of the strip that forms the reflector may be selected to determine how light is projected from the rod.

A plurality of radial bores may be spaced apart along the length of the rod. Each bore may be configured to receive a powered LED light source so that light emitted from each LED is directed parallel to the central longitudinal axis of the body and generally normal to the axis of the bores, and such that light is substantially totally internally reflected within the rod. The spacing and number of bores/LED light sources may vary according to the length of the rod, the amount of light required to be emitted from the light and the amount of light each LED may emit.

The depth and circumference of the bores may vary according to the diameter of the rod and size of the LEDs, but may be such that the LEDs can reside entirely within the rod. The LEDs may be of a type known in the art. The bores may have a semi-circular to circular cross section sufficiently large to accept an LED light therein but also sufficiently small as to minimise space between the light and rod. The bores may be filled with an index matching liquid or resin to aid in heat dissipation away from each LED and enhance light coupling into the internal rod structure, or be left filled only with air.

A reflective layer may be located at each end of the rod to reflect light back into the rod.

Light emitted by the LEDs may be caused to be diffused by total internal reflection down the length of the rod. Reflective layers at the end of the rod may reflect light back along the rod, minimising loss of light through the ends of the rod and further diffusing the light. Light emitted from the rod towards the reflector may be reflected back into or through the rod, or if the reflector is spaced apart from the rod, a beam of light may be emitted away from the reflector. Other light emitted from the rod may also be emitted in a general direction away from the reflector thereby creating a directional light.

An opaque backing may be aligned behind or about the reflector. The opaque backing may be comprised of a thermally conductive material. The thermally conductive material may be a metal or metal alloy.

The LEDs may be mounted directly upon the opaque backing. The LEDs may be mounted upon a mounting strip or strips. The mounting strip or strips may be mounted to the opaque backing. An electric circuit may couple the LED lights to at least one end connection of the substantially tubular shape of the light. The electric circuit may couple the lights to only one end of the substantially tubular shape, with the light emitting a similar amount of light to a comparable fluorescent light having a circuit coupled to both ends. Having only one circuit in this regard can save in manufacturing cost. Optionally, an electric circuit, or circuits, may couple the LED lights to both ends of the substantially tubular shape, particularly when there is a requirement that the light be very bright.

The electrical circuit may be printed onto a circuit board.

The light may be coupled to only a single driver circuit, and this may be coupled to only one end connection. Driver circuits are one of the more expensive components of LED light manufacture and are also one of the components most likely to fail. It can therefore be advantageous to have a light comprised of only one such circuit. Optionally, the light may have driver circuits coupled to both ends of the substantially tubular shape. The driver circuit(s) may be located external to the light.

The end connection, or connections may be able to electrically couple with an existing fluorescent tube fitting and make take any form that is required to achieve this. Such forms should be appreciated by those skilled in the art. The end connection may be a cap that distal to the tube fitting end or light end fits over the rod, reflector, circuit and backing and at the tube fitting end has a dual pin connection that mates with the fluorescent tube light fitting. The end connection may at the light end have a semi-circular to circular cross section shape that engages via an interference fit over the assembled opaque backing, mounting strip or strips and rod.

The end connection may act to hold the light parts together alone, or with the assistance of adhesive and/or mechanical fasteners. The internal wall of the end connection as it abuts the rod and opaque backing may include a taper so as to encourage an interference fit between the parts.

The opaque backing may enclose the LEDs and electrical circuit or circuits against the rod. The opaque backing may be semi-circular in shape and extend around approximately 10 to 210 degrees of the rod. The opaque backing may extend around approximately 20, 30, 40, 50, 60, 70, 80, 90, 100, 1 10, 120, 130, 140, 150, 160, 170, 180, 190 or 200 degrees of the rod. The opaque backing may be comprised of a heat conductive material.

The opaque backing may have an interference fit against the rod. The opaque backing may snap onto the rod. The opaque backing may be fixed to the rod via an adhesive and/or mechanical fastener.

The light may have a tubular shape and an overall circular cross-section achieved by at least slightly reducing the cross-section shape of the rod from purely circular to semi-circular, thereby leaving space for the electrical circuit and the opaque backing that, when assembled, combine to form the circular cross-section light. Alternatively, the rod may have a notch or other indentation inside which the light parts described above may be received or retained. Such a design can allow the light described herein to take a general appearance of shape very similar to a standard fluorescent bulb, which can help with customer transition to the light of the invention, and can look more aesthetically pleasing in an environment comprising both lights of the invention and older fluorescent lighting.

The light may be manufactured and/or marketed on its own for retrofitting into existing fittings, or as a new light fitting plus light combination, or as a replacement light for such a combination.

The embodiments described above may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which the embodiments relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

WORKING EXAMPLE

The above described solid state light is now described by reference to a specific example. With reference to Figures 1 and 2, the light (1 ) comprises a tube of similar dimensions to a standard T8 fluorescent bulb, i.e. 4 foot long and 1 inch in diameter. The proportions of the light (1 ) are such that it fits into light fittings for standard T8 fluorescent bulbs. The light (1 ) includes a transparent acrylic rod (2) of semicircular cross-section having a central longitudinal axis.

Spaced evenly along the length of the rod (2) are bores (5) which extend radially into the rod (2). Each is of a depth of and circumference suitable to receive a pair of LEDs (3).

Situated within each of the bores (5) is a pair of LEDs (3), each LED of each pair having an integral circuit board which is mounted back to back with its paired LED. The LEDs of each pair are arranged such that light emitted from each LED is directed generally parallel to the central longitudinal axis and generally normal to the axis of the bores. The LEDs (3) are mounted on a mounting strip (7) that extends along the length of the tube. The LEDs are connected to the mounting strip (7) by upstands (not shown). An electrical circuit extending along the mounting strip connects each pair of LEDs (3) to an end connection (8) at one end of the tube.

Situated proximate to and extending along the length of the rod is a diffusely reflective strip (6) arranged to reflect light emitted from the LEDs (3) and exiting the rod (2). The reflective strip (6) is located against the surface of the rod (2) such that it sits between the surface of the rod (2) and the mounting strip (7). The width of the reflective strip (6) is selected according to the width of reflected beam required. The reflective strip (6) assists in directing light to where it is required, meaning that while the lumens emitted from the light (1) may be less than those of a similar fluorescent bulb, the light that is emitted is directed to where it is required thereby providing equivalent effective lighting.

A reflective layer (not shown) is located at each end of the rod to reflect light back into the rod (2).

A printed circuit board (not shown) is located at the end connection (8). The printed circuit board's contours and width are sufficiently small to nest within the rod (2) and minimise width beyond the end of the rod (2). Two electrical pins (9), suitable to fit with a standard fluorescent light fitting are electrically coupled to the circuit board such that the light (1) can be located into and receive electricity from the light fitting.

The driver circuit for the LEDs (3) is located externally to the light (1), and is of a standard type known in the art. Because of the small number of LEDs (3) used, only one driver circuit is required.

An opaque backing (4) made of metal alloy encloses the LEDs (3), electrical circuit, reflective strip (6) and mounting strip (7) against the back of the rod (2). Being made of a metal alloy, the opaque backing (4) forms an excellent heat sink to help dissipate heat generated by the LEDs (3). Being made of a metal alloy, the opaque backing (4) is also robust thereby providing durability to the light (1 ).

The end connection (8), together with adhesive, acts to hold the rod (2), reflective strip (6), mounting strip (7) and opaque backing (4) together. The internal wall of the end connection (8) as it abuts the rod (2) and opaque backing (4) includes a taper so as to encourage an interference fit between the parts.

The reflective strip (6), mounting strip (7), electrical circuit and opaque backing (4) all extending along the length of the tube are dimensioned and shaped such that they combine with the semicircular rod (2) to form a circular light (1) in cross-section.

The light (1) uses 17-22 watts and emits 1700-2200 lumens, with an expected average life expectancy of over 50,000 hours. The light (1) is 40-60% more efficient than an equivalent fluorescent light.

Aspects of the solid state light are described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the claims herein.

Claims

WHAT IS CLAIMED IS:

1. A solid state light able to be fitted to a standard fluorescent tube light fitting, the light having a substantially tubular shape comprising:

(c) a plurality of radial bores spaced apart along the length of the rod;

disposed back to back so that light emitted from each LED is directed generally parallel to the central longitudinal axis of the body and generally normal to the axis of the bores, whereby light is substantially totally internally reflected within the rod;

(f) an opaque backing, the backing aligned behind or about the reflector.

2. The light as claimed in claim 1 , wherein the end connection is a cap that distal to the tube fitting end or light end fits over the rod, reflector, circuit and backing and at the tube fitting end has a dual pin connection that mates with the fluorescent tube light fitting.

3. The light as claimed in claim 1 or claim 2, wherein the end connection at the light end has a semi-circular to circular cross section shape that engages via an interference fit over the assembled opaque backing, mounting strip or strips and rod.

4. The light as claimed in any one of the above claims, wherein the end connection acts to hold the light parts together alone, or with the assistance of adhesives and/or mechanical fasteners.

5. The light as claimed in any one of the above claims, wherein an internal wall of the end connection as it abuts the rod and opaque backing includes a taper so as to encourage an interference fit between the parts.

6. The light as claimed in any one of the above claims, wherein the electrical circuit driving the LED lights is coupled to only one end connection.

7. The light as claimed in any one of the above claims, wherein the light only uses a single driver circuit to operate the light.

8. The light as claimed in claim 7, wherein the driver circuit is located external to the light.

9. The light as claimed in any one of the above claims, wherein the opaque backing encloses the LEDs and electrical circuit against the rod.

10. The light as claimed in any one of the above claims, wherein the opaque backing is semicircular in shape and extends around approximately 10 to 2 0 degrees of the rod.

11. The light as claimed in any one of the above claims, wherein the opaque backing is a

material that is heat conductive.

12. The light as claimed in any one of the above claims, wherein the LEDs are directly attached to the opaque backing.

13. The light as claimed in any one of claims 1 to 11 , wherein the LEDs are mounted onto a mounting strip or strips and the strip or strips are mounted to the opaque backing.

14. The light as claimed in any one of the above claims, wherein the opaque backing has an interference fit against the rod.

15. The light as claimed in any one of the above claims wherein the opaque backing snaps onto the rod.

16. The light as claimed in any one of the above claims, wherein the opaque backing is fixed to the rod via an adhesive and/or mechanical fastener.

17. The light as claimed in any one of the above claims, wherein the light has a tubular shape and an overall circular cross-section achieved by at least slightly reducing the cross-section shape of the rod from purely circular to semi-circular, thereby leaving space for the electrical circuit and the opaque backing that, when assembled, combine to form the circular cross- section light.

18. The light as claimed in any one of the above claims, wherein the rod is dimensioned and shaped such that it sustains total internal reflection.

19. The light as claimed in any one of the above claims wherein the rod is manufactured from an acrylic material.

20. The light as claimed in any one of the above claims, wherein the reflector is formed of a material to diffusely reflect light emitted from the LEDs.

21. The light as claimed in any one of the above claims, wherein each bore in the rod has a semi-circular to circular cross section sufficiently large to accept an LED light therein but also sufficiently small as to minimise space between the light and rod.

22. The light as claimed in any one of the above claims, wherein a reflective layer is located at each end of the rod to reflect light back along the rod, minimising loss of light through the ends of the rod and further diffusing the light.

23. The light as claimed in any one of the above claims, wherein light emitted by the LEDs is diffused by total internal reflection down the length of the rod.

24. The light as claimed in any one of the above claims wherein the electrical circuit is printed onto a circuit board.

25. A standard fluorescent tube light fitting including a solid state light as claimed in any one of the above claims.