Solid-state lighting lamp

Abstract

A solid-state lighting lamp (10) is disclosed. The solid-state lighting lamp (10) comprises a glass tube (14), an internal member at least partly arranged inside the glass tube (14), and optical means (50) arranged on the glass tube (14), completely covering an inner surface of the glass tube (14) and adapted to at least partly cloak the internal member.

Claims

1. A solid-state lighting lamp, comprising: a glass tube, the glass tube being open at both ends, a glass bulb, the glass tube being arranged inside the glass bulb and directly attached to the glass bulb, an internal member at least partly arranged inside the glass tube, and optical means arranged on the glass tube, completely covering an inner surface of the glass tube and adapted to at least partly cloak the internal member; and wherein the optical means are adapted to redirect light striking the optical means so as to alter the visibility of the internal member.

2. The solid-state lighting lamp according to claim 1, wherein the optical means is a surface structure on the glass tube.

3. The solid-state lighting lamp according to claim 1, wherein an end of the glass tube and an end of the glass bulb are melted together.

4. A solid-state lighting lamp, comprising: a glass tube, the glass tube being open at both ends, a glass bulb, the glass tube being arranged inside the glass bulb and directly attached to the glass bulb, an internal member at least partly arranged inside the glass tube, and optical means arranged on the glass tube, completely covering an inner surface of the glass tube and adapted to at least partly cloak the internal member; and wherein the optical means is an optical foil.

5. The solid-state lighting lamp according to claim 4, wherein the optical means is a prismatic foil.

6. The solid-state lighting lamp according to claim 4, wherein the optical means is a brightness enhancement foil.

7. The solid-state lighting lamp according to claim 4, wherein the optical means is a plastic optical foil.

8. A solid-state lighting lamp, comprising: a glass tube, a glass bulb, the glass tube being arranged inside the glass bulb and directly attached to the glass bulb, an internal member at least partly arranged inside the glass tube, and optical means arranged on the glass tube, completely covering an inner surface of the glass tube and adapted to at least partly cloak the internal member; wherein the internal member comprises: a cylindrical heat spreader having a first section, wherein the first section is arranged inside the glass tube and has substantially the same length as the glass tube; and a solid-state lighting unit adapted to emit light, wherein the solid-state unit is in thermal contact with the heat spreader.

9. The solid-state lighting lamp according to claim 8, wherein the internal member further comprises a driver arranged at least partly inside the cylindrical heat spreader and electrically connected to the solid-state lighting unit.

10. The solid-state lighting lamp according to claim 8, wherein the cylindrical heat spreader has a second section extending outside the glass tube, and wherein an end cap of the solid-state lighting lamp is attached to the second section of the cylindrical heat spreader.

11. The solid-state lighting lamp according to claim 10, wherein the end cap is connectable to an Edison screw socket.

12. The solid-state lighting lamp according to claim 10, wherein the glass tube extends beyond a top of the first section of the cylindrical heat spreader as seen along a longitudinal axis of the solid-state lighting lamp in a direction away from the end cap.

13. A solid-state lighting lamp, comprising: a glass tube, the glass tube being open at both ends, and comprising a glass surface structure; a glass bulb, the glass tube being arranged inside the glass bulb and joined with the glass bulb; an internal member at least partly arranged inside the glass tube; and, an optical means formed on the glass tube, completely covering an inner surface of the glass tube; wherein the optical means comprises the glass surface structure, and is adapted to at least partly cloak the internal member.

14. The solid-state lighting lamp according to claim 13, wherein the glass surface structure comprises prismatic elements selected from the group consisting of facets, micro prisms, and combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

(2) FIG. 1 is a partly cross-sectional perspective view of an SSL lamp according to an embodiment of the present invention.

(3) FIG. 2 is a partly cross-sectional side view of the SSL lamp of FIG. 1.

(4) FIG. 3 is an exploded perspective view of the SSL lamp of FIG. 1.

(5) FIG. 4 is a partly cross-sectional side view of an SSL lamp according to another embodiment of the present invention.

(6) As illustrated in the figures, the sizes of layers and regions may be exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

DETAILED DESCRIPTION

(7) The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

(8) FIGS. 1 to 3 illustrate an SSL lamp 10 according to an embodiment of the present invention. The SSL lamp 10 in FIGS. 1 to 3 is an LED (light-emitting diode) candle lamp. The SSL lamp 10 may be a retrofit lamp.

(9) From top to bottom as seen in FIG. 3, the SSL lamp 10 comprises a glass bulb 12 with a glass tube 14, an optical part 16, an SSL unit 18, a heat spreader 20, a driver insulator 22, a driver 24, and an end cap 26. The SSL unit 18 and the heat spreader 20 may together be referred to as an internal member of the SSL lamp 10.

(10) The glass bulb 12 is candle-shaped (B-shape). The glass bulb 12 could be clear or frosted. The glass bulb 12 can be made by blowing glass in a mold. The wall of the glass bulb 12 is thin and (substantially) uniform. The wall thickness of the glass bulb 12 may for example be in the range of 0.35 mm to 1.00 mm. The glass bulb 12 has a distal top (or tip) 28a and a proximal base 28b relative to the end cap 26. This means that the base 28b is closer to the end cap 26 than the top 28a.

(11) The glass tube 14 may be a standard size extruded glass tube. The glass tube 14 has an open distal end 30a and a proximal end 30b relative to the end cap 26. Like above, this means that the end 30b is closer to the end cap 26 than the end 30a. The glass tube 14 is clear, transparent or at least partly transparent.

(12) The proximal end 30b of the glass tube 14 is joined with the proximal base 28b of the glass bulb 12. The glass tube 14 and the glass bulb 12 may for example be melted together at the proximal end 30b/proximal base 28b, like in incandescent bulbs, but without any pump tube or stem wires. Hence, the glass tube 14 is freestanding, i.e. it is standing alone inside the glass bulb 12 without being attached to the glass bulb 12 except at said proximal end 30b.

(13) The heat spreader 20 is cylindrical. The heat spreader 20 can for example be deep drawn from highly thermally conductive sheet metal, such as aluminum. Alternatively the heat spreader 20 could be cold forged, for example. The heat spreader 20 comprises a first section 32a and a second section 32b. The top of the first section of 32a is closed, forming a top surface 34. The second section 32b may have a larger outer diameter than the first section 32a. The first section 32a of the heat spreader 20 may substantially match the interior of the glass tube 14, and is arranged inside the glass tube 14. The top surface 34 of the first section 32a of the heat spreader 20 may be in level with the distal end 30a of the glass tube 14, as can be seen in FIG. 2. To this end, the glass tube 14 and the first section 32a of the heat spreader 20 may have the same or substantially the same length. The second section 32b of the heat spreader 20, on the other hand, extends outside (or below) the glass tube 14 and glass bulb 12, as also seen in FIG. 2.

(14) The SSL unit 18 is generally adapted to emit light. The SSL unit 18 is mounted on top of the first section 32a of the heat spreader 20, i.e. on the top surface 34. The SSL unit 18 can be mounted to the heat spreader 20 by use of thermally conductive (non-electrical insulative) paste, for optimal thermal performance. The SSL unit 18 may comprise one or more SSL elements 36 acting as light sources. The SSL elements 36 may for example be LEDs. The SSL unit 18 may also comprise a printed circuit board 38, such as an MCPCB (metal-core printed circuit board), on which the one or more SSL elements 36 are mounted. In the illustrated embodiment, the SSL unit 18 is horizontally arranged, i.e. the PCB 38 is transversal to the longitudinal axis 40 of the SSL lamp 10. The light distribution generated by the SSL lamp 10 may be symmetric with respect to the longitudinal axis 40.

(15) The optical part 16 is provided over the SSL unit 18. The optical part 16 in the illustrated embodiment is a TIR (total internal reflection) optic. The TIR optic may be shaped like a cone with a blunt tip. The TIR optic could be injection molded. The TIR optic serves to distribute light emitted by the SSL elements 36 towards the side and also downwards, towards the end cap 26, which is beneficial for a candle lamp. The TIR optic could be replaced by a diffuser or a toroid reflector, for example.

(16) In an alternative embodiment (not shown), the SSL unit 18 could be vertically arranged, to create a more omnidirectional distribution and not requiring an optic to bring the light downwards, although a diffuser may be beneficial to reduce glare or spottiness.

(17) The driver 24 is generally adapted to regulate the power to the SSL unit 18. The driver 24 may also contain electronics necessary for dimming, connectivity, etc. The driver 24 is provided at least partly inside the heat spreader 20. The driver insulator 22 may be provided between the heat spreader 20 and the driver 24. The driver insulator 22 may be shaped like a cylinder, with a closed top. The driver insulator 22 may for example be an inner dielectric coating on the heat spreader 20, or a separate electrical insulator. The driver insulator 22 can be thermoformed. The driver 24 is electrically connected to the SSL unit 18. To this end, holes 42a, 42b may be provided in the top of the heat spreader 20 and the driver insulator 22, respectively, through which holes 42a, 42b electrical conductors between the driver 24 and SSL unit 18 may pass.

(18) The end cap 26 is generally adapted to mechanically and electrically connect the SSL lamp 10 to an external socket (not shown). The end cap 26 may have a mantel 44 and an external threading 46. The end cap can be of the type E14. The end cap 26 may for example be an aluminum end cap. The end cap 26 is attached to the circumferential outer surface 48 of the second section 32b of the heat spreader 20. The cylindrical heat spreader 20 may have a direct thermal connection to the end cap 26. This enables heat sinking through the end cap 26 through conduction, rather than just heat dissipation through convection at the outer surface of the bulb 12/glass tube 14. It is also a cost efficient way to make a strong stable connection between heat spreader 20 and end cap 26 without any intermediate part(s). The second section 32b of the heat spreader 20 may for example be pressed into the mantle 44 of the end cap 26. Hence, the end cap 26 may be press fitted to the heat spreader 20. The end cap 26 may about the proximal end of the joint glass bulb 12 and glass tube 14, i.e. at 28b/30b. In this way, the transition between the end cap 26 and the glass bulb 12 may be smooth.

(19) An optical means in the form of an optical foil 50 is arranged on the glass tube 14, more precisely between the cylindrical heat spreader 20 and the glass tube 14. Differently stated, the optical foil 50 is sandwiched between the glass tube 14 and the cylindrical heat spreader 20. The optical foil 50 is in contact with an inner surface of the glass tube 14 and with an outer surface of the cylindrical heat spreader 20. The optical foil 50 is cylindrical. The optical foil 50 may for example have been formed by bending a rectangular piece of optical foil cut from a large sheet and then attaching the edges together. The glass tube 14, the optical foil 50 and the cylindrical heat spreader 20 are concentrically arranged around the longitudinal axis 40. The optical foil 50 extends from the interface between the first and second sections 32a, 32b to the top of the first section 32a, i.e. to the level of the top surface 34. The optical foil 50 thus covers substantially the entire inner surface of the glass tube 14. The optical foil 50 can for example be made of PC, PMMA, PET, COP, COC, PS, PEI or silicone. The thickness of the optical foil 50 is typically in the range from about 0.1 mm to about 0.5 mm. The optical foil 50 may alternatively be referred to as an optical film. The optical foil 50 may for example be a prismatic foil or a brightness enhancement foil. There are many different types of such optical foils commercially available. For instance, 3M sells brightness enhancement foils under the trade name Vikuiti.

(20) In use, the SSL lamp 10 is fitted in an external socket, and power is supplied from the external socket via the end cap 26 and the driver 24 to the SSL unit 18, so that light is emitted. Heat generated when the SSL lamp 10 is on may be dissipated partly through conduction to the end cap 26 (max 5%), partly through radiation (less than 40%), and the rest through convection by the ambient air. Further, in use, the heat spreader 20 is cloaked by the optical foil 50 as seen from outside of the SSL lamp 10 by an observer 52. The optical foil 50 redirects incident light in such a way that the visibility of the heat sink 20 for the outside observer 52 is reduced. For example, a brightness enhancement foil may be adapted to redirect light striking the foil perpendicularly so that the light goes back in the approximately same direction from which it came. So a brightness enhancement film can be used as a kind of reflector that redirects light in such a way that the observer 52 cannot see, or at least almost cannot see, the heat sink 20 from the perpendicular view.

(21) FIG. 4 discloses another SSL lamp 10 which is similar to the SSL lamp 10 described above in connection with FIGS. 1 to 3, but without the glass bulb 12. The SSL lamp 10 comprises: a glass tube 14; a cylindrical heat spreader 20 having a first section 32a arranged inside the glass tube 14 and a second section 32b extending outside the glass tube 14; an SSL unit 18 mounted on top of the first section 32a of the cylindrical heat spreader 20; a driver 24 provided at least partly inside the cylindrical heat spreader and electrically connected to the SSL unit 18; and an end cap 26 attached to the second section 32b of the cylindrical heat spreader 20. The first section 32a of the cylindrical heat spreader 20 is shorter than the glass tube 14 as measured along the longitudinal axis 40 of the SSL lamp 10. The glass tube 14 extends beyond the top of the first section 32a of the cylindrical heat spreader 20 in the direction away from the end cap 26 towards the cylindrical heat spreader 20 and along the longitudinal axis 40. There is thus a longitudinal gap between the top of the cylindrical heat spreader 20 and the distal end 30a of the glass tube 14. The heat spreader 20 is typically less than 15 mm shorter than the glass tube 14. The distal end 30a of the glass tube 14 is closed.

(22) An optical means in the form of an optical foil 50 is arranged between the cylindrical heat spreader 20 and the glass tube 14, similarly to how the optical foil 50 in FIGS. 1 to 3 is arranged. The inner side of the closed distal end 30a of the glass tube 14 is covered by the optical foil 50, so light emitted by the SSL unit 18 strikes the optical foil 50. The optical foil 50 may be adapted to affect the light emitted by the SSL unit 18 similarly to how the optical part 16, described above in connection with FIGS. 1 to 3, affects light. For example, the optical foil 50 may be adapted to diffuse the light emitted by the SSL unit 18. In those applications where the SSL unit 18 comprises LEDs of different colors, the optical foil 50 may be adapted to mix light having different colors.

(23) In an alternative embodiment (not shown), it may be that the optical foil 50 does not extend all the way up to the distal end 30a of the glass tube 14. The optical foil 50 would then typically cover the entire first section 32a of the cylindrical heat spreader 20.

(24) The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, the glass bulb can have a different shape than the shape illustrated in FIGS. 1 to 3, such as the shape of a P45 bulb.

(25) Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.