AU2006100666A4 - Lighting system - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT Name of Applicant: Actual Inventor: Address for Service: Invention Title: Xmas-Mil Display Products Pty Ltd, of 1 Melrich Road, Bayswater, Victoria 3153, Australia Rodney Leonard MILLER DAVIES COLLISON CAVE, Patent Attorneys, of 1 Nicholson Street, Melbourne, Victoria 3000, Australia "Lighting system" The following statement is a full description of this invention, including the best method of performing it known to us: 1 Q:\OPER\SGW\2006 JULY-DEC\AUG\12803470 INNOV PAT FIL, REP INV DOC 4/8/06 PIOPER\SpA206Vu'h Dmc\I28AO47O zp dm-04O6 -2- Lighting system The present invention relates to lighting systems, in particular solar powered light emitting diode lighting systems, such as those used for Christmas tree lighting or display lighting.

Lighting systems are used to enhance the visual appearance of objects and product displays either indoors or outdoors, such as Christmas trees, and special event decorations. Outdoor decorative lighting is usually a low voltage, either 12 or 24 volts AC, that is powered by transformers from the main electricity supply. The lights have traditionally been incandescent bulb type lighting in miniature form, which are often referred to as 'bud lighting'.

Due to the relatively high power consumption of bud lights, light emitting diodes, or LEDs, have replaced the incandescent bulb in some applications. However, light emitting diodes were primarily omni-directional in light emission and cycled slowly so that a shimmer was visible to the naked eye. They were also somewhat dull and were only available as coloured, ie non white, light emitting diodes.

Although light emitting diodes used much less power than incandescent bulbs, powering a light emitting diode lighting system by solar power was bulky and expensive as the batteries and solar panels were necessarily large if large numbers of light emitting diodes, eg greater than 100, in a string were to be illuminated. Further the installation was not particularly aesthetic if large panels were used. Such large applications therefore required connection to the main power supply which increased the running costs. These large applications also used alternating current or AC rather than direct current or DC as was obtainable from solar power.

Accordingly the present invention provides a lighting system including a plurality of light emitting diodes; a rechargeable battery connected to and providing power to the light emitting diodes; and P\OPER\Sgl2O061Jul Dcc\I1203470 Ipc doc-04W/0N 6 -3solar panel means connected to the battery to recharge the battery; wherein the battery capacity in Ampere Hours and the output rating of the solar panel in Amperes are minimised while the number of light emitting diodes (lLED) and the hours of illumination (h, 1 1 are maximised according to the following equations: L x x S R x ;and B n lXI lD x hl, xSxnY where h,,n is the average hours of sunlight on the solar panel, S is the safety factor, nrdays is the number of days of operation of the lighting system without recharging the battery and ILED is the current drawn by 100 light emitting diodes in Amperes, and wherein ILED is between 0.4 and 0.43.

The lighting system of the present invention enables the number of light emitting diodes and hours of illumination to be maximised for a given battery capacity and output rating of the solar panel. Alternatively, for a given number of light emitting diodes and hours of illumination, the minimum battery capacity and output rating of the solar panel can be determined. This enables the greatest illumination with the smallest current supplying components.

In one embodiment, the lighting system further includes a controller for controlling the illumination time of the light emitting diodes. The controller may include a programmable timer to illuminate the light emitting diodes between a start time and an end time, the start time and end time being input into the controller. The controller may also provide lighting effects such as flashing or chasing in which only half of the light emitting diodes are illuminated at any one time.

In yet another embodiment, the current drawn by 100 light emitting diodes is between 0.415 and 0.42 Amperes. In still another embodiment, the current drawn by 100 light P \OPER\SgwU()6Jul Dc\12034)70 sp¢ dc-04/0)A)6 -4emitting diodes is 0.416 Amperes.

Preferred embodiments of the present invention will now be described by way of example only with reference to the Figure in which: Figure 1 is a schematic representation of a lighting system according to one embodiment of the present invention.

A decorative lighting system 10 includes a plurality of light emitting diodes 12 in the form of a string of light emitting diodes 13 which provide the lighting to a display such as advertising boards, buildings, trees or other objects. The number of light emitting diodes 12 in the string and the length of the string of light emitting diodes 13 is determined by the lighting requirements of the display. The string of light emitting diodes 13 is typically formed by a twisted pair of insulated electrical conductive wires 14 with light emitting diodes 12 being spaced at regular intervals along at least a part of the length of the string.

In this arrangement the string is relatively easy to manufacture and can have an appropriate aesthetic appearance, for example the insulation coating on the wires can be coloured to match the background of the display to blend in with the display. It should be appreciated that the string of light emitting diodes 13 may also be a flat two wire string, a flexible tape, a three wire cable, a five wire cable or any other suitable cable or electrically conductive arrangement.

A string of light emitting diodes 13 is also preferred as the string can be shaped to form any required shape or to conform to the shape of a building or tree for example, providing flexibility in the applications of the use of the lighting system. However, the light emitting diodes 12 may also form part of a fixed installation, for example in the form of edge lighting for a sign. Further, the string of light emitting diodes may also be formed with a main string with smaller string extending from the main string, for example to provide an icicle effect or tree branches. The smaller strings may be integrally formed with the main string, or connected to the main string by a connector or adaptor.

P \OPER\Sg UI()6UJl Dec\12803470) spc doc-4)A)MA)6 The string of light emitting diodes 13 is connected to a battery 16 which supplies power to the light emitting diodes 12 via the electrically conductive wires 14 of the string 13. In the embodiment shown, the battery 16 is rechargeable, such as a Nickel-metal hydride or leadacid battery.

To enable the battery 16 to be recharged, the battery 16 is also connected to a solar panel 18 such as a Suntech STA010-12 solar module. The solar panel 18 converts solar energy received by the panel into electrical energy to recharge the battery 16.

The battery capacity in Ampere Hours and the output rating of the solar panel in Amperes can be minimised to reduce the size and cost of the lighting system whilst the number of light emitting diodes (nLED) and the hours of illumination can be maximised to maximise the illumination of a display according to the following equations: X ILE, x S Rxh ;and B [C x luDI xh i x Sx nay where is the average hours of sunlight on the solar panel, S is the safety factor, ndays is the number of days of operation of the lighting system without recharging the battery and ILED is the current drawn by 100 light emitting diodes in Amperes. The value of ILED is between 0.4 and 0.43, although in certain embodiments ILED is 0.416. The safety factor should be at least 1.20 to allow for up to a 20% margin of variance in the hours of sunlight, efficiency of the system or leakage of the power from the system. In some applications, a safety factor of 1.25 is required to allow for up to 25% margin of variance in the hours of sunlight, efficiency and leakage of the system.

Accordingly, for each display situation, either the number of light emitting diodes and hours of illumination can be maximised or the capacity of the battery and solar panel output rating can be minimised given a particular set of values for the other parameters.

P ,OPER\S 1 Q(X)6Uul Dc\lU 0347)0 spc docO4flSA)K -6- Maximising the number of light emitting diodes and hours of illumination enables a larger display to be illuminated for a longer period of time. Minimising the battery capacity and the solar panel output rating reduces the size of the system and therefore cost of the system O to operate and install. Further a smaller solar panel is more aesthetic than a larger panel

INO

O 5 which is important where the display is also visible during daylight hours.

O A controller may also be included in the system for controlling the lighting of the light emitting diodes. The controller may include a programmable timer in which the start time and end time of the illumination of the display can be input such that the controller controls the illumination between these times only. Further the controller may include a mode control device to provide a flashing, chasing, twinkling, reverse chasing, skipping dimming or text mode, or combination of two or more of these modes, for additional visual effects to the display. In some of these modes only 50%, or less, of the light emitting diodes may be illuminated at any one time. It should be appreciated that where the controller controls both the mode and time of illumination, the controller may be a single controller or composed of two or more control modules.

The usage of the above formulas will now be explained by the following exemplary examples.

Example 1 A lighting system is required to illuminate 160 light emitting diodes between the hours of 7pmr and 12 midnight (5 hours) each night during summer, eg November to March. During summer, there is, on average, at least 7.5 hours of sunlight a day however there are periods during the summer where there can be no sunlight for 2 days at a time, ie the battery should have 3 days of capacity. A 25% allowance is made for leakage of the battery power and energy conversion of the solar panel.

P:\OPERiSgw\206Uul Dcll 2803470 spcc doc-04/0806 -7- Accordingly, the minimum output rating of the solar panel can be determined by the first of the equations, as shown below.

I

nL EDL XILED xh x S Rxh,, 100 Substituting for the number of light emitting diodes, hours of illumination, hours of sunlight, the safety factor and the current drawn by the light emitting diodes is approximately 0.42 Amperes the minimum output rating of the panel can be determined.

S x 0.42 x 5 x 1.25 Rx (100 Thus the solar panel should have an output rating of at least 560mA. A commercially available solar panel with an output rating of 0.6A output would be ideal for this situation.

A solar panel with less output rating will not be able to provide enough charge to the battery for recharging in the desired timeframe.

The minimum battery size can also be determined by the second equation.

B f X ILED Xll xS x days Substituting for the number of light emitting diodes, hours of illumination, hours of sunlight, the safety factor and the current drawn by the light emitting diodes is approximately 0.42 Amperes the minimum capacity of the battery can be determined.

B -1 x 0.42 x 5 x 1.25 x 3 [100 P.\OPER\Sg2( 6 u I Dc\l1203470 cd doc.)4W/O))6 -8- Thus the battery capacity must be at least 12.6 Ampere Hours A commercially available battery with a capacity of 14AH would be ideal for this situation. A battery with less capacity will not be able to provide enough power to the light emitting diodes for the required number of days without recharging.

Example 2 A lighting system with the same requirements as in Example 1 except the number of light emitting diodes required is 120.

Substituting for the number of light emitting diodes, hours of illumination, hours of sunlight, the safety factor and the current drawn by the light emitting diodes is approximately 0.42, the output rating of the solar panel should be at least 420mA and the battery capacity should be at least 9.45AH. Thus a commercial solar panel with an output rating of 0.42A would be suitable with a IOAH capacity battery.

Example 3 A lighting system with the same requirements as in Example 2 except the hours of illumination is now from 8pm until 6am (10 hours).

Substituting for the number of light emitting diodes, hours of illumination, hours of sunlight, the safety factor and the current drawn by the light emitting diodes is approximately 0.42 Amperes, the solar panel should have an output rating of at least 0.84A and the battery capacity should be at least 18.9AH. Thus a commercial solar panel with an output rating of 0.9A would be suitable with a 20AH capacity battery.

P XPER\g. NXJl De\=%1280470 spc dm4,cA8f -9- Example 4 A lighting system with the same requirements as in Example 2 except the system operates all year round where there is approximately 5 hours of sunlight per day during winter and the illumination time is for 3 hours a night.

Substituting for the number of light emitting diodes, hours of illumination hours of sunlight, the safety factor and the current drawn by the light emitting diodes is approximately 0.42 Amperes, the solar panel should have an output rating of at least 378mA and the battery capacity should be at least 5.67AH. Thus a commercial solar panel with an output rating of 0.36A would be sufficient with a 7AH capacity battery. Although the solar panel rating is less than that calculated, the increased cost and space of a solar panel with an output rating of 0.42A would not outweigh the slight, approximately lack of recharge by the solar panel to the battery. The safety factor of 25% also allows for the solar panel with slightly less output rating to be used effectively.

Example A lighting system with the same requirements as in Example 1 except the light emitting diodes draw a current of 0.416 Amperes and allowing for 20% leakage of the battery power.

Substituting for the number of light emitting diodes, hours of illumination, hours of sunlight, the safety factor and the current drawn by the light emitting diodes, the solar panel output rating should be at least 532mA and the battery capacity should be at least 11.98AH. Thus a commercial solar panel with an output rating of 0.54A would be sufficient with a 12AH capacity battery.

P \OPERISg2X)6U6 ul Dc\280347)0 pec doc-04)8A)6 Example 6 A lighting system with the same requirements as in Example 3 except the light emitting diodes draw a current of 0.4 Amperes with only 2 days battery capacity as it is rare that there are 2 days of no sunlight in this particular installation.

Substituting for the number of light emitting diodes, hours of illumination, hours of sunlight, the safety factor and the current drawn by the light emitting diodes, the solar panel output rating should be at least 800mA and the battery capacity should be at least 12AH. Thus a commercial solar panel with an output rating of 0.78A would be sufficient with a 12AH capacity battery.

Example 7 A lighting system with a 24 Ampere Hour capacity battery and a 1.2 Ampere output rated solar panel is required to operate for 4 hours during summer conditions, ie 7.5 hours of sunlight per day.

The maximum number of light emitting diodes can be calculated by rearranging the equations and substituting the hours of illumination, hours of sunlight, the safety factor of 1.2 and the current drawn by the light emitting diodes of 0.416 Amperes into both equations as below.

Rxh xlOO n gE x 100 hll X Sx I LED nLED 4 5 0.

72

B

B x 100 nLED Sx ndays x h, x ILED nLED 600.96 P:\OPERWSgw2 6ul D 12803470 spc dC.4A M86 -11- From the first of the above equations, due to the ability of the solar panel to recharge the battery, the maximum number of light emitting diodes that can be illuminated is approximately 450. Under the current conditions, the battery has the capacity to illuminate up to 600 light emitting diodes however, to allow for suitable recharging of the battery, a string of 450 light emitting diodes could be illuminated by this arrangement adequately.

Example 8 A lighting system with the same requirements as in Example 7 except the battery capacity is 7 Ampere Hours and the solar panel output rating is 0.42 Amperes.

From the first of the above equations, due to the ability of the solar panel to recharge the battery, the maximum number of light emitting diodes that can be illuminated is approximately 157. Under the current conditions, the battery has the capacity to illuminate up to 116 light emitting diodes. Thus to allow for suitable battery capacity to operate the light emitting diodes of the system over 3 days without recharging, a string of 110 light emitting diodes could be illuminated by this arrangement.

Claims (5)

1. A lighting system including: a plurality of light emitting diodes; a rechargeable battery connected to and providing power to the light emitting diodes; and solar panel means connected to the battery to recharge the battery; wherein the battery capacity in Ampere Hours and the output rating of the solar panel in Amperes are minimised while the number of light emitting diodes (nLED) and the hours of illumination (hmN) are maximised according to the following equations: n1LE X I/D x SR x h ;and B x IL x h. x Sx n where is the average hours of sunlight on the solar panel, S is the safety factor, nday is the number of days of operation of the lighting system without recharging the battery and ILED is the current drawn by 100 light emitting diodes in Amperes, and wherein ILED is between 0.4 and 0.43.

2. A lighting system according to claim 1 wherein the system includes a controller for controlling the illumination time of the light emitting diodes.

3. A lighting system according to any one of the previous claims wherein ILED is between 0.415 and 0.42.

4. A lighting system according to any one of the previous claims wherein ILED is 0.416. P \OPER\Sgw2(X)6UJl Dec\ 12803470 spcc doc-04/08106

13- A lighting system substantially as herein before described with reference to any one of the Examples. Dated this 4 th day of August, 2006 Xmas-Mil Display Products Pty Ltd By DAVIES COLLISON CAVE Patent Attorneys for the applicant