Safety endcap assembly for a LED tube

Abstract

A safety endcap assembly to be arranged at an end of an LED lamp. It has an endcap base element, an endcap cover element, a connector pin, a contact element for connecting to the connector pin to LEDs, and a switch button. The endcap cover element is moveable between a protracted position and a retracted position, and the switch button is moveable between a first position and a second position. The switch button is arranged to disconnect contact element from the LEDs when the switch button is in the first position. The safety endcap assembly further has a switch opening mechanism configured to move the switch button to the first position when a certain condition is met.

Claims

1. A safety endcap assembly to be arranged at an end of an LED lamp having a plurality of LEDs, the safety endcap assembly comprising: an endcap base element to be arranged at an end of a housing of the LED lamp; a connector pin extending along an axis; an endcap cover element moveable relative to the endcap base element along the axis, between a protracted position, in which the endcap cover element is more away from the endcap base element, and a retracted position, in which the endcap cover element is closer to the endcap base element; a contact element for electrically connecting the connector pin to the LEDs; a switch button movable between a first position and a second position, wherein the switch button is arranged to disconnect contact element from the LEDs when the switch button is in the first position, and wherein the safety endcap assembly further comprises: a first spring mechanism for urging the endcap cover element towards the protracted position; and a switch opening mechanism configured such that in case the switch button is in the second position, and the endcap cover element moves from the retracted position towards the protracted position over a predetermined distance, the switch button is moved to the first position.

2. The safety endcap assembly according to claim 1, wherein the contact element is connected to the connector pin via a spring, wherein the spring defines a variable length, including a first length, in which the spring is less compressed, and a second length, in which the spring is more compressed, wherein the first length, the second length and the predetermined distance are arranged to satisfy a following inequality:
D<AB, where D is the predetermined distance, A is the first length, and B is the second length.

3. The safety endcap assembly according to claim 1, wherein the switch button comprises a hole, wherein, in the first position, the hole is not aligned with the contact element in the axis, and in the second position, the hole is aligned with the contact element in the axis, wherein, when the endcap cover element is in the retracted position and the switch button is in the second position, the contact element extends through the hole of the switch button.

4. The safety endcap assembly according to claim 1, wherein the switch button comprises a first surface and a second surface, wherein the first surface and the second surface are substantially perpendicular to the axis, and wherein a distance between the first surface and the second surface is at least 0.4 mm.

5. The safety endcap assembly according to claim 4, wherein the switch button comprises a hole forming a third surface extending from the first surface to the second surface, wherein the third surface forms an angle less than 60 degrees with respect to the first surface or the second surface.

6. The safety endcap assembly according to claim 1, wherein the switch opening mechanism comprises: a second spring mechanism for urging the switch button towards the first position; a switch arresting mechanism configured to arrest the switch button in the closed position when the endcap cover element is in the retracted position, and to release the switch button, in case the endcap cover element moves from the retracted position towards the protracted position over the predetermined distance.

7. The safety endcap assembly according to claim 1, wherein the switch opening mechanism comprises an cantilevered beam or a torsion spring.

8. The safety endcap assembly according to claim 1, wherein the switch opening mechanism comprises an elongated protrusion or recess for arresting the switch button, wherein the protrusion or recess has a length substantially equal to the predetermined distance.

9. The safety endcap assembly according to claim 1, wherein the safety endcap is configured such that the LEDs are only connected to the connector pin when the endcap cover element is in the retracted position and the switch button is in the second position.

10. The safety endcap assembly according to claim 1, wherein, in the protracted position, the switch button is covered by the endcap cover element, and in the retracted position, the switch button is exposed.

11. An LED lamp arrangement configured to be fit in a fixture of a luminaire, the LED lamp arrangement comprising: a housing; a plurality of LEDs arranged in the housing; a safety endcap assembly on at least one end of the housing; and an electrode for electrically connecting the contact element to the LEDs; wherein the safety endcap assembly comprises: an endcap base element to be arranged at an end of a housing of the LED lamp; a connector pin extending along an axis; an endcap cover element moveable relative to the endcap base element along the axis, between a protracted position, in which the endcap cover element is more away from the endcap base element, and a retracted position, in which the endcap cover element is closer to the endcap base element; a contact element for electrically connecting the connector pin to the LEDs; a switch button movable between a first position and a second position, wherein the switch button is arranged to disconnect contact element from the LEDs when the switch button is in the first position, and wherein the safety endcap assembly further comprises: a first spring mechanism for urging the endcap cover element towards the protracted position; and a switch opening mechanism configured such that in case the switch button is in the second position, and the endcap cover element moves from the retracted position towards the protracted position over a predetermined distance, the switch button is moved to the first position.

12. The LED lamp arrangement according to claim 11, wherein the switch button comprises a hole, wherein, when the endcap cover element is in the retracted position and the switch button is in the second position, the contact element extends through the hole of the switch button to come into contact with the electrode.

13. The LED lamp arrangement according to claim 11, wherein the switch button comprises a first surface and a second surface, wherein the first surface and the second surface are substantially perpendicular to the axis, and wherein the contact between the contact element and the electrode is arranged in a space between the first surface and the second surface.

14. The LED lamp arrangement according to claim 13, wherein the switch button comprises a hole forming a third surface extending from the first surface to the second surface, wherein the third surface forms an edge arranged to break the contact between contact element and the electrode.

15. The LED lamp arrangement according to claim 11, wherein with the endcap cover element in its protracted position the LED tube assembly does not fit in the lamp fixture; and with the endcap cover element in its retracted position the LED tube assembly fits in the lamp fixture.

16. A method for operating an LED lamp arrangement in a luminaire, the LED lamp arrangement comprising a safety endcap assembly, wherein the safety endcap assembly comprises: an endcap base element to be arranged at an end of a housing of the LED lamp; a connector pin extending along an axis; an endcap cover element moveable relative to the endcap base element along the axis, between a protracted position, in which the endcap cover element is more away from the endcap base element, and a retracted position, in which the endcap cover element is closer to the endcap base element; a contact element for electrically connecting the connector pin to the LEDs; a switch button movable between a first position and a second position, wherein the switch button is arranged to disconnect contact element from the LEDs when the switch button is in the first position, and wherein the safety endcap assembly further comprises: a first spring mechanism for urging the endcap cover element towards the protracted position; and a switch opening mechanism configured such that in case the switch button is in the second position, and the endcap cover element moves from the retracted position towards the protracted position over a predetermined distance, the switch button is moved to the first position, the method comprising: moving the endcap cover element towards the protracted position in accordance with shape change of a fixture of the luminaire; and moving the switch button from the second position to the first position, in case the switch button is in the second position, and the endcap cover element moves from the retracted position towards the protracted position over a predetermined distance, the switch button is switched to the first position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The advantages of this invention will be apparent upon consideration of the following detailed disclosure of exemplary non-limiting embodiments of the invention, especially when taken in conjunction with the accompanying drawings wherein:

(2) FIG. 1 shows an embodiment of the LED lamp 1 which comprises a safety endcap assembly according to the invention.

(3) FIGS. 2A-2C show an embodiment of the safety endcap assembly according to the invention.

(4) FIGS. 3A-3D shows an operation of an embodiment of the safety endcap according to the invention.

(5) FIG. 4 shows another embodiment of the safety endcap assembly according to the invention.

(6) FIGS. 5A-5G show several states and a corresponding operation of a similar embodiment of the safety endcap assembly as FIG. 4.

(7) FIGS. 6A-6B schematically shows an embodiment of a spatial relationship between elements of a safety endcap assembly according to the invention.

(8) FIGS. 7A-7B show two embodiments of a contact element and a switch button in the safety endcap assembly according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(9) FIG. 1 shows an embodiment of the LED lamp arrangement 1 according to the invention. The LED lamp arrangement 1 comprises a housing 3, a plurality of LEDs arranged in the housing 3, a first endcap assembly 9 and a second endcap assembly 25. In the embodiment shown, the second endcap assembly 25 is a safety endcap assembly 200 according to the invention.

(10) In the embodiment shown, the LED lamp 1 is an elongated tube, in which the housing 3 has an elongate shape. The LED lamp 1 may also have other shapes, such as a circular shape.

(11) FIGS. 2A-2C show an embodiment of the safety endcap assembly 200 according to the invention. This embodiment may be used in the LED lamp arrangement 1 as shown in FIG. 1.

(12) In the embodiment shown, the safety endcap assembly 200 comprises two connector pins 205, 207 a switch button 213, an endcap base element 201 to be arranged at an end of the housing 3 of the LED lamp 1, and an endcap cover element 203.

(13) The endcap base element 201 and an endcap cover element 203 may be arranged to move relative to each other. In the embodiment shown, the endcap cover element 203 is arranged to slide along a circumferential wall 201b of the endcap base element 201. The relative movement between the endcap base element 201 and the endcap cover element 203 defines a protracted position (as shown in FIG. 2A), and a retracted position (as shown in FIGS. 2B and 2C). In the protracted position, the endcap cover element 203 is more away from the endcap base element 201; in the retracted position, the endcap cover element 203 is closer to the endcap base element 201.

(14) The switch button 213 is moveable in two or more positions, including a first position and a second position. The movement may include (but is not limited to) a rotation movement. In the embodiment shown, the switch button 213 can be rotated from the first position (as shown in FIGS. 2A and 2B) to the second position (as shown in FIG. 2C). The relative movement between the endcap base element 201 and the endcap cover element 203, together with the movement (e.g. rotation) of the switch button 213, makes it possible to define at least 22=4 operation states. This degree of freedom can ensure the user safety during installation, and additionally allows a switch opening mechanism to be arranged to open the switch when the risk of arcing increases.

(15) In a preferred embodiment, the safety endcap is configured such that the LEDs are only connected to the connector pins 205, 207 when both of the following conditions are met: (1) the endcap cover element 203 is in the retracted position, and (2) the switch button 213 is in the second position. The advantage of this arrangement is two-fold. First, this provides a double security to the user. As long as the switch button 213 is in the first position, the user can feel free to install the lamp without having to worry about the electrical shock. Second, a mechanism can be added to move the switch button 213 from the second position to the first position (thereby disconnecting the LEDs from the connector pins) when there is an increasing risk of arcing. In this way, the risk of arcing can be reduced.

(16) Optionally, as shown in the dotted line in FIG. 2A, in the protracted position, the switch button 213 is hidden, for example covered by a circumferential wall of the endcap cover element 203. This way provides an additional layer of safety for the installation, because it reduces the risk that user accidentally rotates the switch button 213.

(17) In embodiments shown above and below, the safety endcap assembly comprises two connector pins 205, 207. In this case, the LED lamp arrangement 1 has two pins on each side, i.e. four pins in total, just like a typical fluorescent lamp. In this way the user can install the LED lamp in a simple manner just like in the case of fluorescent lamps. Alternatively, the safety endcap assembly may have only one connector pin.

(18) FIGS. 3A-3D shows an operation of a similar embodiment of the safety endcap assembly according to the invention. The safety endcap assembly in this embodiment may comprise one or more features of the embodiment in FIGS. 2A-2C.

(19) FIG. 3A shows a default state in this embodiment. The default state may be the state before the LED lamp is installed onto the fixture 302, 303 of the luminaire 301. In this embodiment, the default state corresponds to the state FIG. 2A, i.e. the endcap cover element 203 is in the protracted position, and the switch button 213 is in the first position. In this state, the LEDs are disconnected from the connector pins 205, 207.

(20) FIG. 3B shows a state in which the LED lamp is placed into the luminaire. In this embodiment, this states is similar to the state in FIG. 2B, i.e. the endcap cover element 203 is in the retracted position, and the switch button 213 is in a first position. In a preferred embodiment, as long as the switch button 213 remains in the first position (as the case in FIG. 3A and FIG. 3B), the LEDs remains disconnected during the installation. In this way, the user does not need to worry about the electrical shock when he puts the lamp into the fixture, which corresponds to the transition from FIGS. 3A to 3B.

(21) FIG. 3C shows a state in which the LEDs are ready to operate. In this embodiment, this state is similar to the state in FIG. 2C, i.e. the endcap cover element 203 is in the retracted position, and the switch button 213 is in a second position. In this state, the connector pins 205, 207 are connected to the LEDs for conducting the current.

(22) FIG. 3D shows a state after a certain time of use and a switch opening mechanism has been triggered to avoid arcing. The switch opening mechanism may use one or more of the same mechanisms as described in US 2016/0290606 A1, herewith incorporated by reference. As shown in the figure, the fixture 302, 303 of the luminaire no longer maintains its shape, e.g. due to a pressure applied on the fixture 302, 303, Accordingly, the endcap cover element 203 moves from the retracted position towards the protracted position over a certain distance. The safety endcap assembly according to the invention is designed such that, when this distance reaches a predetermined threshold, the switch button 213 automatically switches back to the first position, thereby disconnecting the LEDs. In this way, the LEDs can be disconnected before the deformation of the luminaire reaches the point at which arcing starts to occur.

(23) FIG. 4 shows another embodiment of the safety endcap assembly 200 according to the invention. This embodiment may comprise one or more features as described above under FIGS. 1, 2A-2C, 3A-3D, and may further comprise some more details as will be described below.

(24) In the embodiment shown in FIG. 4, each connector pin 205, 207 is connected to an electrically conductive connection spring 221, 223. Each spring 221, 223 is in turn connected to an electrically conductive contact element 217, 219. This makes it possible for the connector pin 205 to establish an electrical connection with the LEDs via the connection spring 221, 223 and the contact element 217, 219. The connection springs 221, 223 and the contact elements 217, 219 extend through holes 218, 220 in the endcap cover element 203 towards the switch button 213.

(25) In this embodiment, the switch button 213 also comprises two holes. When the switch button is in the second position, the two holes are aligned with the contacting elements 218, 220. This allows the contacting elements 217, 219 to extends through the holes of the switch button 213 to come into contact with electrodes 229, 231, which are electrically connected to the LEDs.

(26) In the embodiment shown, the safety endcap assembly 200 further comprises a spring 45 for pushing the endcap cover element 203 and a spring 215 for rotating the switch button 213. The spring 45 functions to urge the endcap cover element 203 towards the protracted position, and the spring 215 functions to urge the switch button 213 towards the first position. Spring 215 is activated when the endcap cover element 203 moves from the retracted position towards the protracted position over a predetermined distance. In this way, spring 45 gradually moves the endcap cover element 203 towards the protracted position as the fixture 302, 303 deforms, and when this movement reaches the predetermined distance, the spring 215 is activated and moves the switch button 213 to the first position, thereby disconnecting the LEDs from the connector pins 205, 207 to avoid arcing.

(27) In the embodiment shown, the spring 45 is a coiled spring, and the spring 215 is a torsion spring. Other types of springs can also be used. For example, spring 215 may be implemented as a coil spring configured to generate a torque on the switch button 213. One or both of springs 45 and 215 may also be replaced by one or more of other components which perform similar functions. For example, grooves may be arranged on a side surface of the switch button 213 to rotate the switch button as the spring 45 pushes the endcap cover element 203.

(28) In the embodiment shown, the electrodes 229, 231 are arranged in the safety endcap assembly. These electrodes may alternatively be arranged outside the safety endcap assembly, e.g. as a part of the LED circuit board in the LED lamp arrangement 1.

(29) FIGS. 5A-5G show several states and a corresponding operation of an embodiment of the safety endcap assembly according to the invention. The safety endcap assembly in this embodiment may comprise one or more features as described under FIG. 4.

(30) FIG. 5A shows a state in which the endcap cover element 203 is in the protracted position and the switch button 213 is in the first position (similar to FIGS. 2A and 3A), In this state, the connection springs 221, 223 are not compressed, and the contact elements 217, 219 are not in contact with the front surface of the switch button 213.

(31) FIG. 5B shows a state in which endcap cover element 203 is in the retracted position and the switch button 213 in the first position (similar to FIGS. 2B and 3B). In this state, the connection springs 221 and 223 are compressed to push the contact elements 217, 219 against the front surface of the switch button 213, because the holes of the switch button 213 are not aligned with the contact elements 217.

(32) FIG. 5C shows a state in which the endcap cover element 203 is in the retracted position and the switch button 213 in the second position (similar to FIGS. 2C and 3C). In this position, the holes of the switch button 213 are aligned with the contact elements. The tips of the contact elements 217, 219 are thus pushed through the holes by the connection springs 221, 223, allowing the contact elements 217, 219 to come into contact with the electrodes 229, 231, thereby connecting to the LEDs.

(33) As shown in FIGS. 5C and 5D, in the second position of the switch button 213, the spring 215 is biased. In this state, the spring 215 carries an energy for forcing the switch button 213 into the first position. To maintain the switch button 213 in the second position when the LED lamp is installed, the safety endcap assembly 200 further comprises a switch arresting mechanism 239 that locks the switch button 213 in the second position.

(34) An example of the switch arresting mechanism 239 is a lock as shown in FIGS. 5D and 5E. In this embodiment, the lock comprises a protrusion arranged to engage with the switch button 213 when the endcap cover element 203 is in the retracted position. Alternatively, the lock may comprise a recess. The lock has a length substantially equal to the predetermined distance. This allows the switch arresting mechanism 239 to continue to arrest the switch button 213 as the endcap cover element 203 moves, until the movement reaches the predetermined distance.

(35) As shown in FIG. 5F, the spring 45 is arranged to assert a spring force between the endcap base element 201 and the endcap cover element 203. As the luminaire fixture changes its shape, the spring 45 pushes the endcap cover element 203 away from the endcap base element 201, as shown in Arrow I. In the embodiment shown, the mechanical lock 239 is arranged in the endcap cover element 203 and the switch 213 is arranged in the endcap base element 203.

(36) As shown in FIG. 5G, as the endcap cover element 203 moves over a predetermined distance D, the switch button 213 is no longer locked by the switch arresting mechanism 239. As a result, the spring 215 rotates the switch button 213 from the second position to the first position (as shown in Arrow J). In this embodiment, the spring force provided by spring 215 is arranged to overcome the spring force generated by the springs 221, 223, to allow the switch button 213 to break the contact between the electrodes 229, 231 and the contact elements 217, 219 so as to disconnect these elements.

(37) FIGS. 6A-6B show an embodiment of a safety endcap assembly which can tolerate the deformation of the fixture of a luminaire. The figures show a connector pin 207, a spring 223, a switch button 213, an electrode 231 and a switch arresting mechanism 239. These elements may have the same structure and/or function as in FIGS. 5A-5G. This embodiment may also comprise any other elements described above.

(38) In this embodiment, spring 223 defines a variable length. Due to different degrees of the compression of the connection springs 221, 223, the distance between the connector pins 205, 207 and the contact elements 217, 219 can vary. In this way, as the endcap cover element 203 moves towards the protracted position (e.g. due to the deformation of the luminaire fixture), the contact elements 217, 219 can remain in contact with the electrodes 229, 231 to tolerate the deformation.

(39) To avoid arcing, this tolerance is preferably larger than the predetermined distance (D), to ensure that the contact elements 217, 219 and the electrodes 229, 231 stay in contact until the switching opening mechanism is activated. In this embodiment, the variable length defined by the connection springs 221, 223 include a first length (A) (which may correspond to the natural state of the springs 221, 223 in the absence of an external force), as shown in FIG. 6A, and a second length (B) (which may correspond to the compression state of the springs 221, 223 when the endcap cover element 203 is in the retracted position and the switch button 213 is in the second position), as shown in FIG. 6B.

(40) In this embodiment, the connection springs 221, 223 are configured such that the first length A, the second length B and the predetermined distance D (e.g. the length of the protrusion or recess in the switch opening mechanism 239) satisfy to the following inequality:
D<AB.

(41) In this way, as the predetermined distance D is less than the difference between the first length A and the second length B, at the point when the switch opening mechanism is activated, the contact element 217, 219 and the electrodes 229, 231 can remain in contact with each other. In this way, the switch button 213 can act to disconnect the contact element 217, 219 from the electrodes 229, 231 before arcing occurs.

(42) FIGS. 7A and 7B show two embodiments of the switch button 213, a contact element 219 and an electrode 231 according to the invention. These elements may be used in the safety endcap assembly as described above.

(43) In the embodiments shown, the holes of the switch button 213 is arranged in substantially the same position in the longitudinal axis as the contact between the respective contact elements 217, 219 and electrodes 229, 231, to ensure that the switch button 213 can cut into the contact.

(44) In both embodiments shown, the switch button 213 comprises a first surface 213a, a second surface 213b, and a third surface 213 which defines the hole of the switch button 213. The third surface 213 extends from the first surface 213a towards the second surface 213b. The third surface 213c forms an angle with respect to the first surface 213a. This angle is preferably less than 60 degrees.

(45) Preferably, the third surface 213c and the first surface 213a or second surface 213b define a blade or an edge, as shown in FIG. 7B.

(46) In this way, the blade or edge makes it easier for the switch button 213 to cut into the position, to ensure that the of the third surface 213c comes into contact with the tip of the contact element 217, 219, to assert a force to push back the contact elements 217, 219 in the direction hey extend. The decrease of the angle increases the force component in this direction, so smaller angle (e.g. less than 60 degrees) makes it easier for the switch button 213 to force itself between the contact elements 217, 219 and the electrodes 229, 231.

(47) As shown in both FIGS. 7A and 7B, the tip of the contact elements 217, 219 are preferably dome shaped. In these embodiments, when the switch button 213 is moved towards the first position, the sloped portion will hit the dome shaped tip of the contact elements 217, 219 and assert a force in the direction of the connection springs 221, 223. The more towards the top of the dome, the easier the switch button 213 can push back the contact elements 217, 219.

(48) While the principles of the invention have been set out above in connection with specific embodiments, it is to be understood that this description is merely made by way of example and not as a limitation of the scope of protection, which is determined by the appended claims,