GB2528251A

GB2528251A - Lighting apparatus

Info

Publication number: GB2528251A
Application number: GB1412433.3A
Authority: GB
Inventors: Andrew Young
Original assignee: AY CAPITAL Ltd
Current assignee: AY CAPITAL Ltd
Priority date: 2014-07-13
Filing date: 2014-07-13
Publication date: 2016-01-20
Also published as: GB201412433D0

Abstract

A lighting apparatus 1 comprising one or more light emitting diodes (LEDs) 5 mounted on a flexible printed circuit board 3 to form an elongate light-emitting strip, wherein the light-emitting strip has a bent formation to emit light in multiple directions and the lighting apparatus 1 further comprises a casing 7 to hold the lighting apparatus 1 in the curved formation. The light emitting strip may be twisted, curved or a combination of both. The arrangement replicates the lighting effect of a conventional incandescent bulb.

Description

Lighting Apparatus The present invention relates to improved LED lighting apparatus LED lighting for domestic use is becoming increasingly popular. LED light fittings for homes, offices, industrial units etc. are attractive to a user because of the improved energy efficiency when compared to conventional lighting means, such as fluorescent or halogen lighting. The improved energy efficiency of LED5 allows for reliable illumination, with a reduced chance of light failure, at a reduced cost and in a more environmentally-friendly manner.

Known LED lighting comprises LED lighting chips mounted onto flat fibre or metal printed circuit boards (PCB5). The LED lighting chips are a point source of light and emit light in a substantially forward direction, which is a disadvantage when compared with incandescent or fluorescent lighting, which emits light in multiple directions; for example to produce a cylindrical or spherical volume of illumination. Known LED lighting only offers restricted illumination when compared to traditional lighting sources. Typically, the illuminated area from known LED lighting is a cone of light with a limited cross sectional area having an angle of around 120 degrees. For a LED array mounted on a rigid PCB, the majority of light emitted is directed downwardly, i.e. perpendicular to the circuit board. It is known to provide flexible LED "rope" lights, but these are only suited to decorative purposes because of the low level of light output. Such flexible LED lighting is not suited to use in the home or office environments, especially when it is desirable for the LED lighting unit to have a compact shape.

Existing solutions to achieve a more effective spread of emitted light include combining the LED5 with an arrangement of lenses, or the use of multiple PCB5 mounted at various different angles. However, the use of multiple PCB5 increases the power consumed by the light fitting and the complexity of the device. Such complex LED arrays are not capable of creating a uniform spread of light or comparable illumination to traditional light fittings. There remains a need to make use of the environmental, efficiency and cost benefits of using LED5 to achieve low power consumption, whilst achieving a desirable lighting effect. This has been found to particularly desirable if the LED light fitting is being used to replace a small traditional light fitting.

The present invention sets out to provide an improved LED lighting apparatus, which alleviates the problems described above.

In one aspect, the invention provides a lighting apparatus comprising one or more light emitting diodes (LED5) mounted on a flexible printed circuit board to form an elongate light-emitting strip, wherein the light-emitting strip has a curved formation to emit light in multiple directions and the lighting apparatus further comprises a casing to hold the lighting apparatus in the curved formation.

It is understood that the light emitting strip may comprises a flat, narrow belt or have a cylindrical shape. By shaping the lighting apparatus into a curved formation a desired lighting effect suitable for domestic or office use can be achieved, both in terms of the intensity and direction of light emitted. The lighting apparatus of the present invention offers much improved energy efficiency and provides the associated environmental and cost benefits, when compared to conventional incandescent or fluorescent light bulb.

Preferably, the curved formation of the lighting apparatus is configured to replicate the lighting effect of a conventional incandescent or fluorescent light bulb.

By replicating the lighting effect of a conventional incandescent or fluorescent light bulb the present invention can conveniently and easily be used without a user needing to replace any associated lighting accessories, such as lamp shades; or change the positioning of the lighting apparatus within a room or office.

Preferably, the curved formation of the light-emitting strip is formed by twisting the light-emitting strip about its own axis.

By twisting the elongate light-emitting strip about its own axis, the LED5 mounted thereon emit light in 360 degrees about the axis of the strip.

Preferably, the curved formation of the light-emitting strip is formed by bending the light-emitting strip to form at least one curve.

More preferably, the curved formation of the light-emitting strip is formed by twisting the light-emitting strip about its own axis and bending the light-emitting strip to form a curve.

Preferably, the light-emitting strip is bent to form a curve such that a straight length of the light-emitting strip is substantially perpendicular to the axis about which the light-emitting strip is twisted.

Preferably, the straight length of the light-emitting strip is at more than about 65-degrees to the axis about which the light-emitting strip is twisted. More preferably, the straight length of the light-emitting strip is at more than about 75-degrees to the axis about which the light-emitting strip is twisted. Still more preferably, the straight length of the light-emitting strip is at more than about 85-degrees to the axis about which the light-emitting strip is twisted.

By twisting and curving the formation of the light-emitting strip, the lighting apparatus can be configured to emit light in all directions and the illumination can be optimised according to the intended purpose of the apparatus without comprising the electrical connections.

Preferably, the casing is made of aluminium.

The aluminium casing holds the lighting apparatus in place, i.e. maintains the desired shape, whilst allowing for adequate heat dissipation to prevent over-heating and any associated risk of failure of the apparatus.

Preferably, the or each LED is aligned with an aperture in the casing.

The present invention arrives at the optimum performance for the lighting apparatus by balancing the size of the LED5; the number of LED5; the spacing of the LED5, whilst achieving the desired three-dimensional light output. The spacing and number of LED5 is also carefully determined to balance heat dissipation and performance.

Preferably, the lighting apparatus comprises multiple LED5 mounted to face outwardly on both sides of the flexible printed circuit board.

More preferably, alternate LED5 are mounted to face outwardly on the opposing sides of the flexible printed circuit board and are offset from each other.

Preferably, alternate LED5 mounted to face outwardly on opposing sides of the flexible printed circuit board are offset from each other so that the rear face of each LED does not overlap with any other LED.

Preferably, the or each aperture in the casing and the respective LED aligned therewith is covered by a transparent cap.

More preferably, the transparent cap is made of PerspexTM.

The or each Perspex cap provides electrical insulation around and between the LED5 without trapping heat or interfering with light emitted from the apparatus.

Preferably, the lighting apparatus further comprises a connection means.

More preferably, the connection means is at the base of the lighting apparatus.

By providing an electrical connection means compatible with known light fittings, the lighting apparatus can be conveniently fitted to existing devices without requiring any additional tooling.

Preferably, the lighting apparatus comprises a power driver.

More preferably, the power driver is separable from the light apparatus.

For the purposes of clarity and a concise description, features are described herein as part of the same or separate embodiments; however it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

Within this specification, the term "about" means plus or minus 2O%, more preferably plus or minus lO%, even more preferably plus or minus 5°/o, most preferably plus or minus 2°/o.

The invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which:-Figure 1 is a schematic cross-sectional diagram showing a preferred embodiment of a lighting device constructed in accordance with the present invention; Figure 2 is a schematic cross-sectional diagram showing a second embodiment of a lighting device constructed in accordance with the present invention; and Figure 3 is a cross-sectional diagram showing the layers within the lighting apparatus of the present invention.

Referring to Figures 1, 2 and 3, the lighting device 1 of the present invention comprises a flexible, elongate printed circuit board (PCB) 3.

High-power LED5 5 are mounted on both opposing faces of the PCB 3. The size of the LED5 used are selected according to the required level of light output. If LED5 with a greater light output are required, the arrangement of the lighting device 1 will be configured to compensate for the greater amount of heat generated; that is, the LED5 5 are spaced far enough apart to prevent any over-heating of the device 1. The spacing between each LED 5 is sufficient to allow for heat dissipation between adjacent LED5 5 whilst achieving the desired lighting effect. Positioning the LED5 S too close to each other increases the risk of failure due to increased risk of over-heating. It is envisaged that, in a preferred embodiment of the present invention, a greater number of lower output LED5 are incorporated into the lighting device 1 because this generates a lower overall amount of heat. However, any considerations regarding the heat generated by the lighting device are weighed against the desire for the size of the lighting device to be compatible for fitting into existing domestic/office based light fittings; for example where 40W or 60W incandescent light bulbs are currently used.

In an example embodiment of the present invention, between 10 and 50 LED5 5, each of 2-6 microwatt power are used to produce a lumen output that is comparable with a conventional incandescent light bulb and having a physical size that is comparable with such a conventional incandescent light bulb.

As shown in Figure 3, the LED5 5 are mounted in a staggered or offset formation, so that LEDs 5 on opposing faces of the PCB do not overlap with each other. The rows of LED5 5 mounted on both sides of the PCB 3 are each held in place by an aluminium casing 7 formed from two parallel flat, elongate metalwork strips 7. The two parallel aluminium strips 7 form the outer casing of the lighting device 1 to hold the shape of the lighting device 1. The aluminium outer casing 7 is shaped according to the intended purposed of the lighting device 1 and holds the PCB 3 and the mounted LED5 5 in the required formation, as shown in Figures 1 and 2.

As shown in Figure 3, there are apertures 7a spaced evenly along the aluminium casing 7, each of which is aligned with an LED 5. The use of the aluminium casing 7 allows for adequate heat dissipation, whereby heat emitted from any LED 5 does not interfere with the performance of any adjacent LED 5 or any LED 5 on the opposing face of the PCB 3. The aluminium casing 7 acts a passive heat exchanger, i.e. a heat sink for the lighting device 1. Each aperture 7a is covered by a transparent PerspexTM cap 11. The outer surface of each Perspex cap 11 protrudes minimally or is "flush", i.e. aligned, with the outer face of the respective aluminium casing 7, such that the outer surface of the lighting device 1 is continual.

The PerspexTM caps 11 provide electrical insulation around and between the LED5 5 without trapping heat. The lighting device 1 comprises a narrow belt with an array of LED5 5 arranged along its length and on both of its faces. The belt-like lighting device 1 is then shaped; for example twisted and curved, to achieve a three-dimensional light output.

As shown in Figures 1 and 2, the lighting device 1 further comprises a power driver and a standard connection means 13 at the base of the lighting device 1. The power driver (not shown) is separable from the lighting device so that a user can replace the power driver in the event of failure and continue to use the LED S arrangement of the lighting device 1. For example, the power driver is connected to the lighting device by a suitable socket-plug arrangement. The standard connection means 13 allows the lighting device 1 to be fitted to existing connectors/sockets. For example, the lighting device has a bayonet or screw-fit connection means 13 that is compatible with household lamps or ceiling light fittings. The use of a flexible PCB 3 allows the LED lighting device 1 of the present invention to be formed to any desired shape; for example a curved or twisted shape. The shape of the apparatus is achieved without compromising the electrical connections and is configured to optimise the illumination provide by the lighting device 1 according to its intended purpose.

As shown in Figure 1, in a preferred embodiment of the present invention, the PCB 3 and the aluminium strip casing 7 are shaped by twisting the lighting device 1 about its own axis, as indicated by arrow A, to provide light output from the LED array 5 in an approximately cylindrical volume of illumination, i.e. light from the LED5 5 is emitted around 360 degrees from the vertical axis about which the device 1 is twisted. The PCB 3 is then curved, as indicated by arrow B, to form a straight length perpendicular to the axis about which the device 1 is twisted. That is, the straight length is perpendicular to the central axis of the cylindrical illuminated volume. The configuration shown in Figure 1 further spreads the volume of illumination of the lighting device 1, such that light is submitted substantially in all directions.

In a second embodiment of the present invention, shown in Figure 2, the PC is twisted about its own axis, as indicated by arrow A, to provide light output from the LED array 5 in an approximately cylindrical volume of illumination, i.e. light from the LED5 S is emitted around 360 degrees from a vertical axis as indicated by arrow C. It is understood that there are multiple possible configurations for the shape of the PCB 3, which is held in place by the aluminium casing 7, and so multiple possible configurations for the illumination provided by the lighting device 1. The embodiments illustrated in Figures 1 and 2 are provided to illustrate how the present invention can be applied to achieve comparable lighting effects to known conventional lighting devices, such as widely-used incandescent and compact fluorescent light bulbs. This allows a user to continue to use the same lighting accessories, such as light shades, and keep the same positioning for any installed light fittings.

In alternative embodiments of the present invention, it is envisaged that multiple PCB5 can be used to achieve the desired shape of illuminated area/volume.

The above described embodiment has been given by way of example only, and the skilled reader will naturally appreciate that many variations could be made thereto without departing from the scope of the claims.

B

Claims

Claims 1. A lighting apparatus comprising one or more light emitting diodes (LED5) mounted on a flexible printed circuit board to form an elongate light-emitting strip, wherein the light-emitting strip has a curved formation to emit light in multiple directions and the lighting apparatus further comprises a casing to hold the lighting apparatus in the curved formation.
2. A lighting apparatus according to claim 1 wherein the light emitting strip comprises a flat narrow belt or a cylindrical shape.
3. A lighting apparatus according to any preceding claim wherein the curved formation of the lighting apparatus is configured to replicate the lighting effect of a conventional incandescent or fluorescent light bulb.
4. A lighting apparatus according to any preceding claim wherein the curved formation of the light-emitting strip is formed by twisting the light-emitting strip about its own axis.
5. A lighting apparatus according to any preceding claim wherein the curved formation of the light-emitting strip is formed by bending the light-emitting strip to form at least one curve.
6. A lighting apparatus according to any preceding claim wherein the curved formation of the light-emitting strip is formed by twisting the light-emitting strip about its own axis and bending the light-emitting strip to form at least one curve.
7. A lighting apparatus according to claim 5 or 6 wherein the light-emitting strip is bent to form a curve such that a straight length of the light-emitting strip is substantially perpendicular to the axis about which the light-emitting strip is twisted.
8. A lighting apparatus according to claim 7 wherein the straight length of the light-emitting strip is at more than about 65-degrees to the axis about which the light-emitting strip is twisted.
9. A lighting apparatus according to claim 8 wherein the straight length of the light-emitting strip is at more than about 75-degrees to the axis about which the light-emitting strip is twisted.
10. A lighting apparatus according to claim 9 wherein the straight length of the light-emitting strip is at more than about 85-degrees to the axis about which the light-emitting strip is twisted.
11.A lighting apparatus according to any preceding claim wherein the casing is made of aluminium.
12.A lighting apparatus according to any preceding claim wherein the or each LED is aligned with an aperture in the casing.
13.A lighting apparatus according to any preceding claim comprising multiple LED5 mounted to face outwardly on both sides of the flexible printed circuit board.
14.A lighting apparatus according to any preceding claim wherein alternate LED5 are mounted to face outwardly on the opposing sides of the flexible printed circuit board and are offset from each other.
15.A lighting apparatus according to claim 14 wherein alternate LED5 are mounted to face outwardly on opposing sides of the flexible printed circuit board and are offset from each other so that the rear face of each LED does not overlap with any other LED.
16.A lighting apparatus according to claims 12 to 15 wherein the or each aperture in the casing and the respective LED aligned therewith is covered by a transparent cap.
17.A lighting apparatus according to claim 16 wherein the transparent cap is made of PerspexTM.
18.A lighting apparatus according to any preceding claim further comprising a connection means.
19.A lighting apparatus according to claim 18 wherein the connection means is at the base of the lighting apparatus.
20.A lighting apparatus according to any preceding claim comprising a power driver.
21.A lighting apparatus according to claim 20 wherein the power driver is separable from the light apparatus.
22.A lighting apparatus substantially as hereinbefore described or referred to in Figures 1 to 3.