GB2427762A - Elongate arrays of LEDs - Google Patents

Abstract

An illumination device for use in place of a conventional fluorescent tube, for example to illuminate the facia 4 of a drinks vending machine, comprises a plurality of elongate modules 11, each of which includes an array of wide-angle white LEDs. The modules are joined end to end by connectors (19, Fig 5). The apparatus has a plug (21, Fig 6) so that it can be fitted into a socket for a fluorescent tube, and it may include a transformer to provide a 12 volt supply for the LEDs. The LEDs last longer than a corresponding fluorescent tube and produce less heat, and the modular nature makes the apparatus easier to transport.

Description

ILLUMINATION APPARATUS

The present invention relates to illumination apparatus. More particularly, but not exclusively, it relates to apparatus for illuminating a fascia of an automatic vending machine, and to a vending machine so illuminated.

Traditional coin-operated product vending machines, having clear frontal display windows to show the products on offer, have widely been replaced by vending machines in which a frontal surface of the machine mainly comprises translucent promotional and/or decorative material, back-lit from within the machine. This decorative illuminated fascia is often interrupted only by a small panel providing coin (or card) payment facilities and means to select a desired product, and a hatch or port through which the selected product is dispensed.

The fascia of the vending machine frequently comprises a door which may be unlocked and swung open to allow the machine to be stocked or maintained. Whether the fascia is fixed or openable, there is rarely more than about 250mm depth available behind the fascia to hold the illumination arrangements.

As a result, such machines are normally lit by means of two substantially vertically extending conventional fluorescent tubes, located close behind the translucent fascia. These are most commonly of a standard size, approximately 5 feet long (approximately 1.5 metres), a typical vending machine being around 6 feet (around 1.8 metres) tall overall. As well as being more conveniently dimensioned, fluorescent tubes also entail lower power consumption than incandescent lamps of equivalent brightness, and produce less waste heat, which is particularly important where the products stored for vending are cooled or chilled.

Although vending machines as described above are in widespread use (perhaps 150,000 at present in the United Kingdom alone), they still have some distinct shortcomings. The typical life of the fluorescent tubes in service is only about eight months. Furthermore, the loss of one tube leaves the machine half-darkened, which is likely to discourage its use until the tube is replaced. The tubes also have a tendency to fail together, or one soon after the other. A service visit to the vending machine typically every four months is likely.

Although the unit cost of such tubes in bulk is only 1 or so, the cost of calling out an engineer at short notice to travel to the machine and swap over a tube could currently be as high as 50. The cost of disposal of fluorescent tubes is also significant. One further problem with the standard five-foot long tubes is that they are too long to be transported easily in a hatchback or estate car, and even some smaller vans. The engineer therefore requires a relatively large van, which is more expensive to acquire and run.

Fluorescent tubes, while more efficient than incandescent lighting, still only convert electrical energy to light at about 5% efficiency. Vending machines may be left on 24 hours a day, 7 days per week, so the lighting costs may be considerable. There is also sufficient waste heat, even from a fluorescent tube, to make a difference to the running costs of the cooling/chilling arrangements of the vending machine.

It is hence an object of the present invention to provide illumination means adapted for use in a vending machine fascia or the like, which obviates the above disadvantages while providing reliable, low-cost, convenient and effective illumination.

According to a first aspect of the present invention there is provided lighting apparatus for a vending machine fascia or the like comprising a plurality of elongate lighting modules, each provided with a substantially longitudinally-extending array of light-emitting diodes (LEDs), and at least one connector means to link the modules in longitudinal series so as to form a single elongate unit.

Preferably, the or each connector means links the modules both structurally and electrically.

Advantageously, the or each connector means electrically links the modules in series.

Preferably, said array of LEDs on each module comprises a single linear array.

Advantageously, said linear array is substantially straight.

Each lighting module may be substantially straight.

Every LED of the lighting apparatus may be disposed in a single substantially straight linear array.

Preferably, the lighting apparatus is provided with at least one terminal unit adapted to be received in a conventional fluorescent tube socket.

Advantageously, the lighting apparatus is provided with two said terminal units disposed at opposite ends of the apparatus.

The lighting apparatus is preferably provided with means to convert an alternating current power supply to a direct current power supply.

Said conversion means advantageously converts a mains alternating current to direct current at a substantially lower voltage, optionally to approximately 12 volts d.c.

Preferably, at least some of the plurality of LEDs, optionally each LED, comprises a white LED.

Advantageously, each LED comprises lens means so adapted that light emitted thereby diverges through an angle of at least ninety degrees, optionally through an angle of at least one hundred and twenty degrees.

Each said lens means may be so adapted that light from a respective LED diverges substantially symmetrically.

Preferably, the connector means link the modules to form a substantially rigid body.

Advantageously, the apparatus comprises a plurality of connector means, each directly connectable, optionally rigidly, to neighbouring connector means.

Each connector means may extend longitudinally of each module connected thereby, optionally in contact therewith.

Each connector means may extend generally half-way along each said module connected thereby.

Preferably, the LEDs of each module are electrically connected as a plurality of groups, the LEDs of each group being connected in series and each group being connected in parallel with each other group.

Advantageously, each group of LEDs also comprises resistor means connected in series with the LEDs.

According to a second aspect of the present invention, there is provided an elongate lighting module comprising a plurality of light-emitting diodes (LEDs) arranged in a substantially longitudinally-extending array and means to connect said module structurally and electrically to one or more further said modules.

Preferably, said lighting module is so adapted as to be connectable to form part of a lighting apparatus as described in the first aspect above.

According to a third aspect of the present invention, there is provided a vending machine comprising lighting apparatus as described in the first aspect above.

Preferably, the vending machine comprises a plurality of said lighting apparatus.

Advantageously, the lighting apparatus is so disposed as to illuminate, in use, a majority of a frontal panel of the machine.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a typical vending machine in which illumination apparatus embodying the present invention may be used; Figure 2 is a scrap cross-sectional view of a frontal panel of the vending machine shown in Figure 1, with a conventional fluorescent lighting tube in position; Figure 3 is a perspective view of a lighting module separated from the illumination apparatus of the present invention; Figure 4 is a schematic representation of a wiring arrangement of part of the lighting module shown in Figure 3; Figure 5 is a scrap side elevation of an intermediate portion of an illumination apparatus embodying the present invention; and Figure 6 is a scrap perspective view of a terminal portion of the illumination apparatus shown in Figure 5.

Referring now to the Figures, and to Figure 1 in particular, a typical vending machine I (in this case adapted to vend cans of soft drink) comprises a main casing 2 with a door 3 hingeably mounted thereto. The main casing 2 contains the cans or other items to be vended and the mechanism to do so. The door 3 may be opened by authorised personnel to re-stock the cans, etc, and to service the machine 1, but is usually locked shut. A frontal portion of the door 3 comprises a generally vertical translucent panel 4, bearing indicia 5 of an informational, promotional or decorative nature, illuminated from within the machine 1 (see Figure 2 and below for details). A payment slot 6 and an array of buttons 7 allowing a user to select a particular product are mounted to the panel 4, and a hatch 8 extending through the panel 4 is connected to the vending mechanism so that cans, etc, may be delivered therethrough. A majority of the frontal panel 4 thus requires illumination.

At present, this is carried out by means of two vertically mounted fluorescent lighting tubes 9, mounted within the door 3 close behind the translucent frontal panel 4. As shown in Figure 2, each fluorescent tube 9 is of conventional form and is mounted between a pair of conventional sockets 10 which retain it in position and provide an appropriate electrical power supply.

The two tubes 9 are arranged so as to illuminate roughly half of the panel 4 each. Thus, should one tube 9 fail, a substantial proportion of the panel 4 will become dark. The vending machine 1 will not stand out so as to attract users from a corresponding direction, and will appear defective, discouraging users. If failure of a first tube 9 leads to failure of the second tube 9 shortly afterwards, as often occurs, the vending machine I will appear to be out of order. It is thus important that the tubes 9 should be replaced as soon as possible, and so maintenance engineers should be on call (at significant expense) for this purpose.

The tubes 9 are usually mounted within the thickness of the door 3. If they are mounted too close to the panel 4, their illumination may be too localised. However, even fluorescent tubes emit some heat when running, which will tend to warm up cans, etc, stored within the machine 1, particularly if the tubes 9 are set back too far into the machine 1. This would also increase the running costs of the chiller apparatus that is usually provided to keep the cans, etc, cold. There is thus no wholly satisfactory location for fluorescent tubes 9 within the machine 1.

The illumination apparatus of the present invention does not use fluorescent tubes, but instead employs a plurality of light-emitting diodes (LEDs), usually white LEDs. The white LEDs currently available have conversation efficiencies approaching 80%, and so it is possible to provide a light output equivalent to a fluorescent tube with an economically practical number of LEDs. The energy wasted as heat will be lower, and the running costs will also be lower than for equivalent fluorescent tubes. The coherent light from LEDs is also found to be more visible in conditions of low general illumination than the randomlyemitted light from fluorescent tubes.

LEDs are usually supplied with the light-emitting diode itself embedded in a clear plastics block, part of which acts as a lens for the light leaving the LED. Most recent development has gone into LEDs with lenses that focus their light into a narrow conical beam, e.g. for torches. However, LEDs can be produced in which their light is spread over a wide angle.

For the present invention, LEDs with a spread angle of over 120 are preferred. They are thus able to illuminate a broad area rather than merely a localised spot, as many existing forms of LED tend to do.

To provide a lighting effect broadly equivalent to a fluorescent tube 9, the illumination apparatus of the present invention comprises a plurality of wide-angle LEDs arranged in a single elongate linear array. So as to illuminate the same area as a five-foot fluorescent tube, the apparatus is also approximately 1.5 metres long overall. However, for convenience in storage and transport, it is made up of several shorter modules which are connected together for installation into the vending machine 1. Five such modules, each 300 millimetres long, are used in the currently preferred apparatus.

One such module 11 is shown in Figure 3. It comprises an elongate narrow strip 12 of conventional printed circuit board (pcb), 300 millimetres long and fifteen millimetres wide.

A single row of surface mounted wide angle white LEDs 13 extends longitudinally along the pcb strip 12. Only fifteen of these LEDs 13 are shown in Figure 3, for simplicity, but in practice thirty LEDs 13 per module 11, making one hundred and fifty for the whole apparatus, will currently give the light output required. It is believed that the next generation of white LEDs will enable this to be reduced to around twenty LEDs 13 per module 11, or one hundred for the whole apparatus.

Figure 4 shows the electrical connections for the LEDs 13, provided on a face of the pcb strip 12 opposite to that shown in Figure 3. Rather than connecting the LEDs 13 all in parallel or all in series, it is preferable to connect groups of adjacent LEDs 13 in series, while connecting these groups in parallel. Thus, a first 14 and a second 15 lateral conductive track extend longitudinally of the pcb strip 12, adjacent opposite edges. The first lateral track 14 leads to a positive terminal 16 at a first end of the pcb strip 12, and the second lateral track 15 leads to a negative terminal 17 (corresponding positive and negative terminals are provided at a second remote end of the pcb strip 12, not shown). The positive and negative terminals 16, 17 are connected in operation to a 12 volt direct current supply. Six adjacent LEDs 13 and a resistor 1 8 are connected in series forming a group, the group as a whole being connected between the first 14 and second 15 lateral tracks. On the thirty-LED module 11 described, there are thus five such groups connected in parallel, each with the others. Six groups of five LEDs 13 could be used, instead. For a twenty-LED module 11, four groups of five LEDs 13 or five groups of four LEDs 13 could be used. In each case, the exact number of LEDs 13 per group is not critical, merely that the resistor 18 in each group is selected to ensure the correct potential drop across each LED 13 in the group.

It should be noted that if one LED 13 should fail, only the corresponding group of LEDs 13 connected in series therewith will also be put out of action. Thus, only a small part of one module 11 of the illumination apparatus will go dark, instead of an entire five-foot fluorescent tube 9, as in the existing arrangements. In any case, the lifetime of LEDs 13 is significantly longer than that of fluorescent tubes 9 (see below).

The assembly of the modules 11 to form the illumination apparatus is shown in Figure 5.

Each adjacent pair of modules 11 is linked by a connector element 19. Each connector element 19 comprises an electrical connector 20 which operatively links the respective lateral conductive tracks 14, 15 of the modules 11 by means of the corresponding positive 16 and negative 17 terminals. The connector elements 19 also physically connect the modules 11 into a substantially rigid single elongate body. In the embodiment shown, each connecting element 19 extends longitudinally half-way along each module 11 connected thereby, so as to meet each neighbouring connecting element 19. Advantageously, neighbouring connecting elements 19 are directly physically connectable. The modules 11 are thus built up into a very long self-supporting body with a single row of LEDs 13 extending from end to end.

At each said end of this body, a plug element 21 as shown in Figure 6 is provided, physically and electrically connected to a respective endmost module 11. The plug element 21 is provided with electrical plug pins 22 and is dimensioned and configured to fit into a conventional socket 10 for fluorescent tubes 9. An illuminating apparatus of the present invention may thus be mounted to any fitting to which a conventional fluorescent tube 9 of the same length may be mounted. There is no need to modify a vending machine (or the like) to fit the illumination apparatus, it may simply be substituted for an existing fluorescent tube 9.

To produce the l2V dc supply required to operate the LEDs 13, it may be convenient to include appropriate transformer arrangements within the plug elements 21, to convert an alternating current mains supply provided through the sockets 10. Alternatively, a suitable transformer/rectifier arrangement may be fitted to the vending machine 1.

As mentioned above, an elongate array of wide-angle white LEDs 13 can produce the same illumination as a conventional fluorescent tube 9, using less electricity and producing less waste heat. The illumination apparatus described is slightly more compact than a fluorescent tube, and because of its modular structure, is far easier to store and transport.

Even should an LED 13 fail, only a small part of the illumination from the apparatus would be lost, and so replacement would probably be less urgent than in the case of fluorescent tube 9 failure. In any case, the current generation of LEDs are being offered with guaranteed lifetimes of 50,000 hours (6.1 years continuous service). Even with a hundred or more LEDs in each unit, the time before a first LED fails is likely to be several years.

Thus, while the initial purchase price of an illumination apparatus as described is likely to be significantly more than that of a conventional fluorescent tube 9, the increased lifetime between failures should substantially compensate for this. In any case, with the current cost of replacement mainly comprising the maintenance engineer's time, the greatly increased service intervals are likely to outweigh heavily any increase in initial purchase costs.

It is also possible that the engineer would be able to remove an illumination apparatus and exchange only those module(s) 11 with failed LED(s) 13, further reducing the cost. (The question of partial or complete replacement is likely to be resolved on the basis of the distribution of lifetimes found for the particular LEDs 13 employed - i.e. where there is little variation in lifetime, it would probably be preferable to replace the entire apparatus as a precaution to save the cost of a further call-out in the near future).

A further benefit from using LEDs is that fluorescent tubes tend to drop around 25% to 35% in light output within their first three months of use, before settling to a generally constant output thereafter. This complicates specifying the tubes to illuminate a particular machine (especially with an expected eight-month service life) and may result in a machine containing one old tube and one recently replaced tube having asymmetric illumination. LEDs do not suffer this problem.

It should be noted that while the illumination apparatus described is particularly suitable and beneficial in the area of vending machine illumination, there are other fields in which it may be of use. For example, many advertising displays and shop fascia boards are back-lit using fluorescent tubes, for which such illumination apparatus may be substituted.

Claims (1)

1. Lighting apparatus for a vending machine fascia means comprising a plurality of elongate lighting modules, each provided with a substantially longitudinally- extending array of light-emitting diodes (LEDs), and at least one connector means to link the modules in longitudinal series so as to form a single elongate unit.

2. Lighting apparatus as claimed in claim 1, wherein the or each connector means links : *". the modules both structurally and electrically. S... I... * . 5..

3. Lighting apparatus as claimed in either claim 1 or claim 2, wherein said array of

I 5*S.

* LEDs on each module comprises a single linear array. *

*.**S* * I :. . Lighting apparatus as claimed in any one of the preceding claims, wherein every LED of the lighting apparatus is disposed in a single substantially straight linear array.

5. Lighting apparatus as claimed in any one of the preceding claims, provided with at least one terminal unit adapted to be received in a conventional fluorescent tube socket, optionally with two said terminal units disposed at opposite ends of the apparatus.

6. Lighting apparatus as claimed in any one of the preceding claims, provided with means to convert an alternating current power supply to a direct current power supply.

7. Lighting apparatus as claimed in any one of the preceding claims, wherein at least some of the plurality of LEDs, optionally each LED, comprises a white LED.

8. Lighting apparatus as claimed in any one of the preceding claims, wherein each LED comprises lens means so adapted that light emitted thereby diverges through an angle of at least ninety degrees, optionally through an angle of at least one hundred and twenty degrees.

9. Lighting apparatus as claimed in any one of the preceding claims, wherein the S...

connector means link the modules to form a substantially rigid body. S. * S * ...

10. Lighting apparatus as claimed in any one of the preceding claims, comprising a * : * * plurality of connector means, each directly connectable, optionally rigidly, to S. ** : neighbouring connector means.

11. Lighting apparatus substantially as described herein with reference to Figures 3 to 6 of the accompanying drawings.

12. An elongate lighting module comprising a plurality of light-emitting diodes (LED5) arranged in a substantially longitudinally-extending array and means to connect said module structurally and electrically to one or more further said modules.

13. A lighting module as claimed in claim 12, so adapted as to be connectable to form part of a lighting apparatus as claimed in any one of claims ito 11.

14. A lighting module substantially as described herein with reference to Figures 3 to 6 of the accompanying drawings.

15. A vending machine comprising lighting apparatus as claimed in any one of claims I to 11, optionally a plurality of said lighting apparatus.

16. A vending machine as claimed in claim 15, wherein the lighting apparatus is so disposed as to illuminate, in use, a majority of a frontal panel of the machine. * ** * S * S... S...

*..* 1 7. A vending machine substantially as described herein with reference to Figures 1 and 3 *** to 6 of the accompanying drawings. S..

S

S.....

S S 5*

S S S

S S