Lighting device and luminaire

Abstract

A tubular LED lighting device (10) comprising an LED, a driver (18) for driving the LED, and an electrical connector (14). The lighting device further comprises a thermally triggered switch (16) for prevention of overheating of the electrical connector. The thermally triggered switch is connected in series between the electrical connector and the driver, and the thermally triggered switch is configured to interrupt current in the event of the temperature of the electrical connector meeting a triggering condition. If a significant degree of arcing occurs the electrical connector will heat up such that the triggering condition will be met and the current flow between the electrical connector and the driver will be interrupted. There is also provided a luminaire (20) comprising the tubular LED lighting device.

Claims

1. A tubular LED lighting device comprising: an LED, a driver for driving the LED, and an electrical connector; the lighting device further comprising a thermally triggered switch for prevention of overheating of the electrical connector, wherein the thermally triggered switch is configured to interrupt current in the event of the temperature of the electrical connector meeting a triggering condition; and wherein the thermally triggered switch is configured to sense the temperature of the electrical connector via a main body or a probe of the thermally triggered switch.

2. The tubular LED lighting device according to claim 1, wherein the thermally triggered switch is one of a thermal fuse, a bimetallic switch and a thermal relay.

3. The tubular LED lighting device according to claim 1, wherein the thermally triggered switch is connected in series with the electrical connector via a connection lead of the thermally triggered switch.

4. The tubular LED lighting device according to claim 1, wherein the thermally triggered switch comprises a circuit breaking part and a temperature detecting part.

5. The tubular LED lighting device according to claim 1, wherein the thermally triggered comprises a single part that performs both circuit breaking and temperature detecting.

6. The tubular LED lighting device according to claim 1, wherein the thermally triggered switch can be reset manually or automatically.

7. The tubular LED lighting device according to claim 1, wherein the triggering condition comprises meeting a predetermined temperature for a predetermined period of time.

8. The tubular LED lighting device according to claim 1, further comprising at least one end cap and the thermally triggered switch is within the end cap.

9. The tubular LED lighting device according to claim 8, wherein the lighting device comprises an electrical connector at each end of the lighting device and the thermally triggered switch is configured to prevent each electrical connector from overheating.

10. The tubular LED lighting device according to claim 8, wherein the lighting device comprises an electrical connector at each end of the lighting device and a thermally triggered switch at each end of the lighting device for prevention of overheating of each respective electrical connector.

11. The tubular LED lighting device according to claim 8, wherein each end of the lighting device comprises two electrical connectors and the thermally triggered switch is configured to prevent each electrical connector from overheating or multiple thermally triggered switches are provided to prevent each respective electrical connector from overheating.

12. A luminaire comprising a tubular LED lighting device according to claim 1.

13. The luminaire according to claim 12, further comprising a HF ballast.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are described in more detail and by way of non-limiting examples with reference to the accompanying drawings, wherein

(2) FIG. 1 shows a total TLED retrofit lamp system;

(3) FIG. 2 shows the gaps between the lamp holder and electrical connectors of the lighting device when poorly connected; and

(4) FIG. 3 shows a thermally triggered switch incorporated in a lighting device of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

(6) As shown in FIG. 3, a thermally triggered switch 16 is included at the power input end of a tubular LED lighting device (TLED) for the prevention of the above mentioned safety problem. In FIG. 3, only one side of lamp system is shown, the other end of the lighting device may be symmetrical.

(7) The tubular LED lighting device 10 comprises an LED, a driver for driving the LED, and an electrical connector 14. The thermally triggered switch 16 is for prevention of overheating of the electrical connector 14. The thermally triggered switch 16 is connected in series between the electrical connector 14 and the driver, and is configured to interrupt current in the event of the temperature of the electrical connector 14 meeting a triggering condition.

(8) The thermally triggered switch 16 may have a connection lead 161 which may be connected to the electrical connector 14 directly. Another connection lead 162 of the thermally triggered switch 16 may be connected to a driver PCB 18 of the tubular LED lighting device 10. In this way, the heat dissipation on to the electrical connector 14 can be easily detected by the thermally triggered switch 16. If an arc is generated between the electrical connector 14 and the electrical connector 24 of the lamp holder 22, the safety device will interrupt current flow when the temperature of the electrical connector 14 reaches a triggering condition. As a result the TLED 10 will shut down as no power is supplied from the HF ballast. Further, the ballast enters a protection mode or shuts down as a result of having an open load. The system will thus not overheat and remain safe.

(9) A particular feature of this lighting device 10 is that the safety features are included in the lighting device, such that retrofitting of the LED lighting device into a fixture or luminaire 20 for a tubular fluorescent lamp also installs the thermally triggered switch 16, without additional action required on the part of the end user.

(10) The thermally triggered switch 16 may be a thermal fuse or a thermal relay. Alternatively, the thermally triggered switch 16 may be any other component capable of interrupting current in the event of the temperature of the electrical connector 14 meeting a triggering condition.

(11) The thermally triggered switch 16 may be connected in series with the electrical connector via a connection lead 161 of the thermally triggered switch. The connection lead can thus function as both an electrical connector and also a thermal connection; this construction can therefore be particularly simple and therefore economic.

(12) The connection leads 161,162 of the thermally triggered switch may be pins, for example if the thermally triggered switch 16 is a thermal fuse the connection leads 161,162 may be pins of a thermal fuse. Alternatively the connection leads 161,162 may be any other electrical connection as will be familiar to the skilled person, for example, copper wires or insulated copper wires.

(13) The thermally triggered switch 16 may be thermally connected to the electrical connector 14. The thermal connection could take place by any means, for example, by means of the connection lead 161 or simply by being in close proximity with the electrical connector 14.

(14) The electrical connector 14 of the TLED 10 may be a lamp pin. The electrical connector 24 of the lamp holder 22 may be a socket. Other electrical connectors 14, 24 will be familiar to the skilled person.

(15) This TLED 10 can also be used as an InstantFit TLED to replace other lamps driven on a current source, for example PL-L, PL-C etc. (PL-L and PL-C designate Philips Pi shape fluorescent lamps). That is, the tubular lighting device 10 may be non-linear. Alternatively, the tubular lighting device 10 may be linear, as is common in the art and known to the skilled person.

(16) The thermally triggered switch 16 may be mounted on a printed circuit board 18 or another carrier. In particular, the thermally triggered switch 16 may be mounted on the same printed circuit board 18 or carrier as the driver.

(17) The thermally triggered switch 16 may additionally function as an electrical connection part between the electrical connector 14 of the lighting device 10 and a printed circuit board 18 or other carrier.

(18) The lighting device 10 may further comprise at least one end cap and the thermally triggered switch 16 may be within the end cap.

(19) The lighting device 10 may comprise an electrical connector at each end of the lighting device 10 and the thermally triggered switch 16 may be configured to prevent each electrical connector from overheating. It is common for lamp fittings for tubular lighting devices to have electrical connectors at both ends and such an arrangement prevents each electrical connector from overheating.

(20) The lighting device 10 may comprise an electrical connector 14 at each end of the lighting device 10 and a thermally triggered switch 16 at each end of the lighting device 10 for prevention of overheating of each respective electrical connector 14. Where economic thermally triggered switches are used such an arrangement may be advantageously economic.

(21) Each end of the lighting device 10 may comprise two electrical connectors 14 and the thermally triggered switch 16 may be configured to prevent each electrical connector 14 from overheating

(22) Alternatively, multiple thermally triggered switches 16 may be provided to prevent each respective electrical connector 14 from overheating. It is common for lamp fittings for tubular lighting devices to have two electrical connectors at each end and such an arrangement prevents each electrical connector of the lighting device from overheating.

(23) As an alternative to that discussed above, the thermally triggered switch 16 may be configured to sense the temperature of the electrical connector 14 via a probe of the thermally triggered switch 16. In this construction heating of the electrical connector results in heating of the probe of the thermally triggered switch 16, in turn this results in interruption of current in the event of the electrical connector 14 meeting the triggering condition. Such a construction may be advantageous, for example, with such a construction it is possible for the thermally triggered switch 16 to be remote from the electrical connector 14 such that more freedom is provided to the designer as to the location of the thermally triggered switch 16. For example, a single thermally triggered switch 16 having two probes may be provided, the first probe may be configured to detect the temperature of an electrical connector at a first end of the lighting device and the second probe may be configured to detect the temperature of an electrical connector at a second, opposite, end of the lighting device; the thermally triggered switch may then be configured to interrupt current in the event of the temperature of an electrical connector at either end of the lighting device meeting a triggering condition, even though some components or elements of the thermally triggered switch may be remote from one or both ends of the lighting device.

(24) The thermally triggered switch 16 may comprise a circuit breaking part and a temperature detecting part. The temperature detecting part and the circuit breaking part may be functionally connected, such that the thermally triggered switch interrupts current in the event of the temperature of the electrical connector meeting a triggering condition. For example, the circuit breaking part may comprise electrical circuitry and the temperature detecting part may comprise a thermistor. In such a case, the electrical circuitry may be configured to detect a change in the electrical characteristics of the thermistor and then interrupt current flow in the event of a triggering condition being reached.

(25) Alternatively, the circuit breaking part and the temperature detecting part may be the same part. For example, the circuit breaking part and the temperature detecting part may both be the fusible link of a thermal fuse.

(26) The thermally triggered switch 16 may be manually resettable. For example, the thermally triggered switch 16 may be a thermal fuse with a manual reset function.

(27) The thermally triggered switch 16 may be automatically resettable. For example, the thermally triggered switch 16 may be a positive temperature coefficient resistance which automatically resets upon removal of an applied voltage after a period of time.

(28) The use of a resettable thermally triggered switch 16 may be advantageous, as after the thermally triggered switch 16 has interrupted a current flow, the lighting device 10 may then be correctly installed and used without the need to replace the thermally triggered switch 16.

(29) The triggering condition may comprise meeting a predetermined temperature for a predetermined period of time. Accordingly, exceeding the predetermined temperature for a short period may not meet the triggering condition, such that interruption of current flow as a result of false positives is avoided. However, if the temperature exceeds the predetermined value for a longer period then the current flow may be interrupted.

(30) There is also provided a luminaire 20 comprising the tubular LED lighting device 10 of the invention. Such a luminaire 20 may provide the advantages discussed above, in particular, the luminaire 20 may be safer than prior art luminaires. The luminaire 20 may comprise a ballast.

(31) The luminaire 20 may be a holder of the lighting device 10, e.g. a ceiling light fitting, an armature for fitting underneath a cabinet or the like, an apparatus into which the lighting device is integrated, e.g. a cooker hood or the like, and so on. The luminaire 20 may comprise a plurality of lighting devices 10. The lighting devices 10 may be fitted in a housing of the luminaire 20 comprising a light exit window. The light exit window may comprise beam shapers such as one or more lens arrays, reflectors and so on. Alternatively, the light exit window may simply be formed by an opening in the housing. The internal surfaces of the housing may be reflective to reflect light that exits the lighting devices 10.

(32) In a non-limiting example, the luminaire 20 may be a ceiling armature, e.g. an armature that may be integrated in a suspended ceiling. Other examples of such luminaires 20 will be apparent to the skilled person.

(33) In an alternative embodiment, there is provided a luminaire for a tubular LED lighting device comprising a ballast, an electrical connector for the lighting device, and a thermally triggered switch for prevention of overheating of the electrical connector. The thermally triggered switch is connected in series between the ballast and the electrical connector and is configured to interrupt current to the LED lighting device in the event of the temperature of the electrical connector meeting a triggering condition.

(34) This can provide similar advantages to the lighting device discussed above; however, the thermally triggered switch is installed separately from the lighting device.

(35) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word comprising does not exclude the presence of elements or steps other than those listed in a claim. The word a or an preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several distinct elements. In the device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.