GB2465966A

GB2465966A - Light emitting diode tube lamp

Info

Publication number: GB2465966A
Application number: GB0821727A
Authority: GB
Inventors: Michael Renecle; Paul Schofield
Original assignee: EXCLED Ltd
Current assignee: EXCLED Ltd
Priority date: 2008-11-28
Filing date: 2008-11-28
Publication date: 2010-06-09
Anticipated expiration: 2028-11-28
Also published as: GB2465966B; GB0821727D0

Abstract

A light emitting diode (LED) tube lamp 20 comprising a tube 22 having a first end 24, second end 26 and electrical connection means 25, 27 at each end for connection to cooperating electrical sockets 12, 14, and a circuit within the tube comprising a plurality of LEDs 28 connected together, wherein the circuit of LEDs is only connected to the electrical connection means at the first end 24 of the tube. A modified starter is also disclosed as part of a kit of said tube and starter, wherein the two connection pins of the starter are connected together as a closed circuit. The LED tube lamp can be retro-fitted as direct replacement of a fluorescent tube lamp in a standard fluorescent light fitting with conventional ballast present.

Description

LED Tube The present invention relates to a LED tube lamp and to a kit for permitting a LED tube lamp to be used in place of a conventional fluorescent tube lamp.

Fluorescent tube lamps have been used for many years, particularly in commercial buildings such as shops, offices, factories, schools etc. Fluorescent tube lamps are preferred to incandescent lamps as they use less power for the same amount of light and they generally last longer.

Fluorescent tube lamps generally consist of a straight glass tube which is capped at each end with a pair of electrical connectors. The tube contains a mixture of mercury vapour and inert gases at a very low pressure relative to ambient pressure. The inside of the tube is coated with a phosphor. There is no direct electrical connection between the pairs of electrical connectors at each end of the tube.

Fluorescent tube lamps work by passing electricity through the mercury vapour, which in turn produces ultraviolet light. The ultraviolet light is then absorbed by a phosphor coating inside the lamp, causing it to glow, or fluoresce. The heat generated by fluorescent lamps is much less than the heat generated by incandescent lamps, but energy is still lost in generating the ultraviolet light and converting this light into visible light. Furthermore, if the lamp breaks then there is a health risk due to the possible exposure to mercury. Typically fluorescent lamps have a life span of around 10,000 -20,000 hours. Once a fluorescent lamp stops working it must usually be disposed of professionally, which results in an increase in costs for users.

A conventional wiring layout (2) for a fluorescent tube lamp is shown in Fig. 1. A standard fluorescent tube lamp (4) consists of a straight glass tube (5) which is capped at each end (6, 7) with a pair of fluorescent filaments (8, 9) on the inside of the tube (5) and a corresponding pair of electrical connector pins (10, 11) on the outside of the tube (5). The tube (5) contains a mixture of mercury vapour and inert gases at a very low pressure relative to ambient pressure and the inside of the tube is coated with a phosphor.

The tube (5) has two electrical connector pins (10, 11) at each end (6, 7) and is symmetrical in all planes, such that it can be inserted into a fitting in four possible orientations. The two ends (6, 7) of the tube (5) are totally isolated from each other, so the tube lamp (4) will not conduct electrically until both sets of pins (10, 11) have been properly inserted into the appropriate electrical fitting (12, 14).

The mains supply is connected to one pin (10a, ha) at each end (6, 7) (at one end the connection is via a ballast (16)) and the other pin (1 Ob, 11 b) at each end (6, 7) is connected to the starter (18), which is located in a starter holder (19). When a fluorescent tube lamp (4) is inserted into a live fitting there may be mains on the first end (10) inserted, but absolutely no connection to the end still being held, and the tube won't conduct' until the second end (11) has been inserted.

The starter (18) is a conventional glow tube starter as is commonly used and will be understood by those skilled in the art. The starter (18) comprises an aluminium tube containing a small volume of gas, e.g. neon. The tube incorporates a switch which is normally in an open position. When power is applied a glow discharge takes place which heats the metal contacts of the switch. A second or so later, the contacts close providing current to the fluorescent filaments, which glow and release electrons into the gas within the tube. Since the glow in the starter is extinguished, there is no longer any heating of the metal contacts and the switch opens. The inductive kick generated at the instant of opening triggers the main discharge in the fluorescent tube to start the lamp.

The starter (18) is a replaceable device which can be removed from the circuit as required.

The starter (18) is selected to match the wattage rating of the fluorescent tube lamp (4).

Recent years have seen a number of developments in relation to the use of light emitting diodes (LED5) for lighting purposes. Although LED lamps tend to be more expensive to purchase than other available alternatives, they have a much longer life span and they are generally cheaper to run. It is envisaged that demand for LED lamps will increase as the technology becomes more affordable. Due to the high number of fluorescent tube lamps in use today, which are generally fitted into purpose designed systems, there is a desire to develop a LED tube lamp which can be used as a replacement for currently available fluorescent tube lamps.

A number of LED tube lamps have been developed and some of these are commercially available. However, there are safety concerns regarding these LED tube lamps, particularly when they are intended to be used as replacements for fluorescent tube lamps and in fittings designed for conventional fluorescent tube lamps. As noted above, in a fluorescenttube lamp there is no direct electrical connection between the electrical pins at one end of the tube and the electrical pins at the opposite end of the tube. This means that it is perfectly safe for a user to hold one end of the tube as they insert the other end into the appropriate fitting. This is because the system does not become "live" until both ends have been inserted. However, an LED lighting element generally consists of a plurality of LEDs wired together in series. In the case of an LED tube lamp this has generally meant that a plurality of LEDs are connected together between the electrical connectors at one end of the tube and the electrical connectors at the other end of the tube.

Due to the symmetry of the tube and the mains connections at each end, the LEDs in the current designs of LED tube have to be powered from both ends of the tube, and both pins at each end. This results in an electrical circuit existing between the pins at each end of the tube. Consequently, there is a high risk of electrocution when a user is fitting a currently available LED tube, as when the LED tube is inserted into one end of a live fitting there is the possibility that mains voltages will appear on the pins at the other end of the half inserted tube. There is a risk that a user may be holding this end of the tube and that electrocution may occur. This problem will occur regardless of whether the ballast and/or starter are fitted or removed.

It is the object of the present invention to overcome some of the problems of the prior art, or at least to offer an alternative form of LED tube lamp.

According to the present invention there is provided a LED tube lamp comprising a tube having a first end, a second end and electrical connection means at each end for connection to cooperating electrical sockets, and a circuit within the tube comprising a plurality of LEDs connected together, wherein the circuit of LEDs is only connected to the electrical connection means at the first end of the tube.

The LED tube lamp can be used as a safe replacement for conventional fluorescent tube lamps. The LED tube lamp offers improved life span and cheaper running costs than conventional fluorescent tube lamps. Furthermore, the LED tube lamp according to the present invention is safer than currently available LED tube lamps. As discussed above, currently available LED tube lamps, which are intended to be used as replacements for fluorescent tubes, have an electrical connection running between the electrical connectors at each end of the tube. Consequently, when a user has inserted one end of the tube into a live socket there is an increased risk of electrocution as the user will be holding the tube on or near the other end of the tube which is now in electrical connection with the mains supply.

The present invention mitigates this risk as the electrical current goes in and out of the same end of the tube and does not pass between the electrical connection means at each end. This results in a LED tube lamp which is effectively as safe as a conventional fluorescent tube, since the electrical connection means at one end of the tube are totally electrically isolated from the electrical connection means at the other end at the other end of the tube, until both ends are safely inserted into the appropriate electrical sockets.

As discussed above, the wiring system for conventionalfluorescent tube lighting systems also includes a starter. A starter is not required in order for the LED tube lamp according to the present invention to operate, and in fact it will not operate correctly with a conventional fluorescent tube starter. For this reason a modified starter must be fitted when the LED tube lamp is used as a replacement for a conventional fluorescent tube. The function of the replacement starter is simply to form an electrical connection across the starter holder. This can be achieved by a variety of means, but a simple solution is a starter plug which fits the holder and in which the two pins which fit into the holder are shorted together. This provides a pathway across the starter holder. Since a starter is not required for the LED tube lamp according to the present invention it is anticipated that purpose designed wiring systems will omit the starter holder and there will no longer be a need for a replacement starter.

In an embodiment of the invention the electrical connection means at the second end of the tube is configured to complete an electrical circuit at a cooperating electrical socket. The function of the electrical connection means at the second end is to complete an electrical circuit at the cooperating electrical socket. As noted above, the electrical connection means at the second end is not connected to the electrical connection means at the first end. In its simplest form the electrical connection means comprises a wire which permits the incoming power supply to flow through the circuit and into the LED circuit at the first end of the tube (as can be better seen with reference to Fig. 2 discussed below). In an embodiment of the invention the electrical connection means comprises a pair of electrical pins. The electrical pins are advantageously configured to make them compatible with the electrical sockets provided in conventional fluorescent tube lamps. In an embodiment of the invention the electrical pins at the first end are connected to the circuit of LEDs and the electrical pins at the second end are connected together.

In an embodiment of the invention the circuit of LEDs are connected in series. In an embodiment of the invention the circuit of LEDs are connected in parallel.

In an embodiment of the invention the electrical connection means are compatible with conventional fluorescent tube lamp sockets. It is envisaged that lighting systems in commercial buildings will eventually be designed specifically for LED tube lamps. However, the vast majority of commercial buildings, and to a lesser extent some residential buildings, are currently constructed with lighting systems designed for fluorescent tube lamps. It is therefore desirable that LED tube lamps according to the present invention are provided with electrical connection means which are compatible with conventional fluorescent tube lamp sockets. This permits the LED tube lamps according to the present invention to be used as immediate replacements for fluorescent tube lamps. As noted above, it may be necessary to replace the starter with a modified starter which effectively bypasses the starter holder.

According to a second aspect of the present invention, there is provided a kit of parts comprising a LED tube lamp as previously described and a replacement starter, wherein the replacement starter is configured to complete a break in an electrical circuit. As noted above, the LED tube lamp of the present invention is intended to be used as a replacement for currently available fluorescent tube lamps. In some cases it will be necessary to bypass the starter holder as conventional starters are not compatible with the LED tube lamp. In view of this it is envisaged that a kit can be produced comprising the LED tube lamp and a suitable replacement starter. The function of the replacement starter is simply to bridge the gap across the starter holder and create an electrical connection.

In an embodiment of the invention the replacement starter comprises electrical connection means which is compatible with conventional fluorescent tube lamp starter holders. In an embodiment of the invention the electrical connection means of the replacement starter comprises a pair of pins for engagement with a starter holder, wherein the pins are connected directly together within a body of the replacement starter. The replacement starter simply bridges the gap between the electrical connections of the starter holder to facilitate the flow of current.

In the cases described no wiring changes are required to the fitting and the act of replacing the fluorescent tube lamp is simple.

An embodiment of the invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows a schematic view of an electrical wiring system for a conventional fluorescent

tube lamp according to the prior art; and

Fig. 2 shows a schematic view of an electrical wiring system incorporating a LED tube lamp according to the present invention.

Fig. 1 shows a schematic view of an electrical wiring system 2 for a lighting system for fluorescent tube lamps 4. The operation of such lighting systems is described above.

Fig. 2 shows a schematic view of an electrical wiring system 2 and a LED tube lamp 20 according to the present invention. The wiring system 2 is identical to the wiring system shown in Fig. 1 (and to the extent that the parts are the same the same numbering will be used) as one of the aims of the present invention is to provide a LED tube lamp 20 which can be used in conventional lighting systems for fluorescent tube lamps 4.

The wiring system 2 comprises an incoming power supply, which will generally be a mains electricity supply. The system 2 further comprises a pair of spaced apart electrical sockets 12, 14, a starter holder 19 and a ballast 16. Both starter holders 19 and ballasts 16 are well known in the prior art and will not be discussed in detail. The electrical sockets 12, 14 are configured to receive the two pairs of electrical pins 10, 11 of a conventional fluorescent tube lamp 4 and to hold the lamp 4 in place securely, but other configurations are also possible, as will be readily appreciated.

The LED tube lamp 20 comprises an elongate, transparent plastic tube 22 which is capped at a first end 24 by first pair of electrical connection pins 25 and capped at a second end 26 by a second pair of electrical connection pins 27. The tube 22 can be made from acrylic or polycarbonate tubing, or glass. The electrical connections are configured to be compatible with the electrical sockets 10, 12 and can take any form as is required by the configuration of the system 2. In the present case the electrical connections are in the form of pins 25, 27.

A circuit of LEDs 28 in series is provided within the tube 22. The LEDs 28 extend along the majority of the length of the tube 22. The number of LED5 28 and the spacing between them will depend on a number of factors, such as the cost of the device, the brightness required and the power of the LEDs. A variety of colours may be used to suit the intended purpose of the tube lamp 20.

The circuit of LEDs 28 is arranged in the form of a loop and the ends of the loop are in electrical connection with electrical connection pins 25 at the first end 24 of the tube. The LED circuit 28 is not connected to the electrical connection pins 27 at the second end 26 of the tube 22.

As noted above, the system 2 is illustrated schematically and the LED tube lamp 20 is shown smaller than actual size to aid in the understanding of the system 2. The LED tube lamp 20 is shown between the electrical sockets 12, 14, but not in contact with them. In use of the LED tube lamp 20, the electrical connection pins 25 at the first end 24 of the tube 22 engage with a first electrical socket 12 and the electrical connection pins 27 at the second end 26 of the tube 22 engage with a second electrical socket 14. It can be seen that regardless of which way the LED tube lamp 22 is fitted into the sockets 12, 14 the tube lamp 20 will not conduct until both ends 24, 26 have been inserted. This arrangement resembles the conventional fluorescent tube lamps 4 in that there is no direct electrical connection between the first 24 and second 26 end of the tube 22.

The electrical connection pins 27 at the second end 26 of the tube 20 are connected together.

The electrical pins 27 at the second end do not power the LEDs 28, but simply complete an electrical circuit, enabling the system to function.

As discussed in relation to Fig. 1, fluorescent tube lamps 4 require fluorescent tube lamp starters 18 in order to function. Starters 18 are not required with LED tube lamps 20 according to the present invention, however the LED tube lamps 20are intended to be useable as replacements for fluorescent tube lamps 4 without the need for re-wiring. A replacement starter 30 is provided for the LED tube lamp 20 which can be inserted into the starter holder 19 of a fluorescent tube lamp system 2 to facilitate operation of the LED tube lamp 20. In its simplest form, as shown in Fig. 2, the replacement starter 30 comprises a short tube 31, of approximately the same size as a conventional starter 18, with two pins 32 which are configured to fit into the starter holder 19. The two pins 32 are connected together inside the tube 31 to effectively create an electrical connection and bypass the starter holder 19.

Although a preferred embodiment of the invention has been described, this is only by way of example. It will be appreciated by those skilled in the art that many modifications and variations of the present invention are possible within the scope of the invention as defined in the claims.

Claims

Claims 1. A light emitting diode (LED) tube lamp comprising a tube having a first end, a second end and electrical connection means at each end for connection to cooperating electrical sockets, and a circuit within the tube comprising a plurality of LEDs connected together, wherein the circuit of LEDs is only connected to the electrical connection means at the first end of the tube.
2. A LED tube lamp according to claim 1, wherein the electrical connection means at the second end of the tube is configured to complete an electrical circuit at a cooperating electrical socket.
3. A LED tube lamp according to claim 1 or claim 2, wherein the electrical connection means comprises a pair of electrical pins.
4. A LED tube lamp according to claim 3 as dependent on claim 2, wherein the electrical pins at the second end of the tube are connected together.
5. A LED tube lamp according to any preceding claim, wherein the circuit of LEDs are connected in series.
6. A LED tube lamp according to any one of claims 1-4, wherein the circuit of LEDs are connected in parallel.
7. A LED tube lamp according to any preceding claim, wherein the electrical connection means are compatible with conventional fluorescent tube lamp sockets.
8. A kit of parts comprising a LED tube lamp according to any preceding claim and a replacement starter, wherein the replacement starter is configured to complete a break in an electrical circuit.
9. A kit of parts according to claim 8, wherein the replacement starter comprises electrical connection means which is compatible with conventional fluorescent tube lamp starter holders.
10. A kit of parts according to claim 8 or claim 9, wherein the electrical connection means of the starter comprises a pair of pins for engagement with a starter holder, wherein the pins are connected directly together within a body of the starter.
11. A LED tube lamp substantially as hereinbefore described with reference to the accompanying drawings.
12. A kit of parts substantially as hereinbefore described with reference to the accompanying drawings.