Illuminant for an LED lamp, and LED lamp

Abstract

A light fixture for an LED lamp having a glass bulb and at least one light-emitting diode. The glass bulb is filled with a heat-conducting gas and the at least one light-emitting diode is arranged inside the glass bulb. The heat-conducting gas in the glass bulb has a pressure of at least 2.2 bar at room temperature.

Claims

1. A light fixture configured to be arranged inside a light-emitting diode (LED) lamp, the light fixture comprising: a glass bulb filled with a heat-conducting gas having a higher thermal conductivity than air and a pressure of at least 2.2 bar at room temperature, wherein the glass bulb is vacuum-sealed by a press or pinch seal such that the heat-conducting gas cannot escape therefrom; at least one light-emitting diode (LED) arranged inside the glass bulb; and at least one electrical connector that extends through the glass bulb from inside to outside the glass bulb such that the at least one LED inside the glass bulb is electrically connectable with the LED lamp outside the glass bulb.

2. The light fixture according to claim 1, wherein the glass bulb contains a gaseous getter material selected from the group consisting of oxygen, a silane, and a combination of oxygen and a silane.

3. The light fixture according to claim 1, wherein the glass bulb contains a solid getter material provided as at least one of a coating and a sintering material inside the glass bulb.

4. The light fixture according to claim 1, wherein the heat-conducting gas includes at least one of helium and hydrogen.

5. The light fixture according to claim 1, further comprising a circuit board inside the glass bulb, wherein the at least one light-emitting diode is arranged on the circuit board.

6. The light fixture according to claim 1, further comprising a plurality of circuit boards inside the glass bulb, wherein the at least one light-emitting diode is arranged on each circuit board.

7. The light fixture according to claim 6, wherein the plurality of circuit boards includes at least three circuit boards, and wherein the plurality of circuit boards are arranged on the lateral surfaces of an imaginary straight prism having an equilateral base surface.

8. The light fixture according to claim 1, wherein the at least one light-emitting diode is at least partially embedded in a conversion material.

9. The light fixture according to claim 1, further comprising a glass support inside the glass bulb, wherein the at least one light-emitting diode is arranged on the glass support between the glass support and the glass bulb.

10. The light fixture according to claim 9, wherein the glass support has the shape of a tube, wherein the at least one light-emitting diode is arranged on an outer lateral surface of the glass support.

11. The light fixture according to claim 1, further comprising at least one LED filament arranged inside the glass bulb, wherein the at least one light-emitting diode comprises a plurality of light-emitting diodes arranged on the at least one LED filament.

12. The light fixture according to claim 9, further comprising a plurality of LED filaments regularly spaced-apart on an outer lateral surface of the glass support, wherein a main extension direction of each LED filament extends along an extension direction of the glass support.

13. A light-emitting diode (LED) lamp comprising: a glass shell filled with a first heat-conducting gas having a higher thermal conductivity than air and a pressure of at least 1 bar at room temperature; and a light fixture arranged inside the glass shell and comprising: a glass bulb filled with a second heat-conducting gas having a higher thermal conductivity than air and a pressure of at least 2.2 bar at room temperature, wherein the glass bulb is vacuum-sealed by a press or pinch seal such that the second heat-conducting gas cannot escape therefrom; at least one light-emitting diode (LED) arranged inside the glass bulb; and at least one electrical connector that extends through the glass bulb from inside to outside the glass bulb such that the at least one LED inside the glass bulb is electrically connectable with the LED lamp outside the glass bulb; wherein the pressure of the first heat-conducting gas is at least 0.5 bar lower than the pressure of the second heat-conducting gas at room temperature.

14. The LED lamp according to claim 13, wherein the pressure of the first heat-conducting gas is at least 1 bar lower than the pressure of the second heat-conducting gas at room temperature.

15. The light fixture according to claim 1, wherein the heat-conducting gas in the glass bulb has a pressure of at least 5.1 bar at room temperature.

16. The light fixture according to claim 1, wherein the heat-conducting gas in the glass bulb has a pressure greater than 5.1 bar but at most 10 bar at room temperature.

17. The light fixture according to claim 1, wherein the glass bulb contains a solid getter material provided as a mass of either a pure metal or an alloy inside the glass bulb.

18. The light fixture according to claim 1, wherein the at least one electrical connector is configured to be electrically connectable with the LED lamp via a solder connection inside the LED lamp.

19. The light fixture according to claim 1, wherein the at least one electrical connector is configured to be electrically connectable with the LED lamp via a pin connection inside the LED lamp.

20. The light fixture according to claim 19, wherein the pin connection is provided as a G4 or a G9 pin connection.

21. The light fixture according to claim 1, wherein the at least one LED is of a chip-on-board (COB) configuration.

22. The light fixture according to claim 1, wherein the getter material comprises a solid getter material comprising at least one of zirconium (Zr) and an alloy of zirconium.

23. The LED lamp according to claim 13, wherein the first heat-conducting gas has a pressure of 1 bar at room temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred further embodiments of the invention are explained in greater detail by the following description of the drawings. In the drawings:

(2) FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4, 5, 6, 7, 8, 9A, 9B, 10A, 10B, 11A, 11B, 12A, 12B, 13A, 13B, 14A, 14B and 14C show exemplary embodiments of a light fixture described here as well as an LED lamp described here.

(3) FIGS. 15A and 15B show measurement curves for explanation of a light fixture described here and an LED lamp described here.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) The light fixture described here as well as the LED lamp described here are explained in greater detail below with reference to exemplary embodiments and the associated drawings. In this case elements which are the same, of the same kind, similar or equivalent are provided with the same reference numerals. Repeated description of some of these elements is omitted in order to avoid redundancies.

(5) The drawings and the size ratios of the elements illustrated in the drawings should not be regarded as drawn to scale relative to one another. On the contrary, individual elements may be shown as excessively large for better illustration and/or to aid understanding.

(6) An exemplary embodiment of a light fixture 10 described here is explained in greater detail with reference to the illustrations in FIGS. 1A and 1B. FIG. 1A shows an illustration of the light fixture 10 in the switched-off state, while FIG. 1B shows an illustration in the switched-on state, that is to say with luminous light-emitting diodes 31.

(7) The light fixture 10 comprises a glass bulb 20 with an extension 22 and a mounting region 21. Furthermore, the light fixture 10 comprises LED filaments 30 with light-emitting diodes 31 and in each case a conversion material 34 which surrounds the light-emitting diode 31 as encapsulation, as well as connectors with a fusion region 40, an inner connection region 41 and an outer connection region 42.

(8) In the illustrated exemplary embodiment, the glass bulb 20 is designed to be cylindrical. The glass bulb 20 is vacuum sealed and is filled with a heat-conducting gas, such as for example helium. The glass bulb 20 can be formed with quartz glass and/or tempered glass or can be made therefrom.

(9) For example, the glass bulb 20 is produced using a glass-blowing technology and/or by means of extrusion. In this case it is possible that first of all a long, tubular glass piece is provided. The glass piece can then be subdivided into several components, wherein a glass bulb 20 can be formed from each component. The extension 22 can be formed at a separation region between the components, for example by thinning of the glass in the separation region. The mounting region 21 can be constructed on a side opposite the extension 22. In the mounting region 21, a vacuum seal can be provided for example by pressing together or crimping the end regions of the component from the glass piece. Before the pressing together the light-emitting diode 31 can be placed in the interior of the component and the interior can be filled with the heat-conducting gas.

(10) The LED filaments 30 are uniformly distributed in the glass bulb 20 and extend along a main extension direction of the cylindrical glass bulb 20. Furthermore, the LED filaments 30 extend along a glass support 25 which cannot be seen in FIGS. 1A and 1B and is arranged in the interior of the glass bulb 20.

(11) The mounting region 21 can serve for holding and electrical contacting of the light fixture 10. The mounting region 21 is in particular constructed in such a way that the interior of the glass bulb 20 is vacuum sealed and the heat-conducting gas contained in the glass bulb 20 cannot escape from the glass bulb 20.

(12) The light-emitting diodes 31 can be contacted by means of the connectors. For this purpose, for example, the outer connection region 42 can be inserted in a holder of an LED lamp 100. The inner connection region 41 can be connected to a contact region 35 of the light-emitting diodes 31.

(13) Further exemplary embodiments of a light fixture 10 of a LED lamp 100 described here are explained in greater detail with reference to the illustrations in FIGS. 2A and 2B. The light fixture 10 of FIGS. 2A and 2B again contains a glass bulb 20. In contrast to the exemplary embodiment of FIGS. 1A and 1B, a circuit board 32 to which light-emitting diodes 31 are attached is arranged in the glass bulb. Moreover, the glass bulb 20 has no additional glass support 25. The light-emitting diodes 31 can be, for example, soldered onto the circuit board 32. A conversion material 34, present for example as a fluorescent layer, can be mounted in each case on the light-emitting diodes 31. Alternatively or in addition, an encapsulation 34, for example in the form of a conversion encapsulation 34, can be mounted on the light-emitting diode 31. It is possible that the glass bulb 20 exclusively contains the first connection region 31 and the circuit board 32 with the light-emitting diodes 31.

(14) In particular, a flat so-called chip-on-board (COB) component is used in the light fixture 10 of FIG. 2B. The light-emitting diodes 31 of the light fixture 10 on a circuit board 32 can be introduced into a conversion material 34. The light-emitting diodes 31 can be attached to the circuit board 32 on both sides or alternatively only on one side. The circuit board 32 can be formed with a material which is partially transparent to radiation (that is to say translucent), such as for example Al.sub.2O.sub.3, and/or from a material which is completely transparent to radiation, such as for example (quartz) glass, or is made from such a material. As a result, in particular in the case of a circuit board 32 equipped on one side, the generated light can be guided onto the other side of the circuit board 32.

(15) The light fixture 10 can additionally contain electronic components, which can be part of a driver electronics, (not visible in FIGS. 2A and 2B). For example, these components can contain a rectifier, by which the series-connected light-emitting diodes 31 are operated at 230 V with a rectified frequency of 100 Hz. In order to avoid gaseous emissions of volatile compounds from the electronic component of the light fixture 11, the gas emission rate of the electronic components should be below a gas emission rate of an encapsulation material surrounding the light-emitting diodes 31, in the ideal case even below the gas emission rate of the conversion material 34.

(16) A further exemplary embodiment of a light fixture 10 of a LED lamp 100 described here is explained in greater detail with reference to the illustrations in FIGS. 3A and 3B. The light fixture 10 comprises in each case a circuit board 32 with light-emitting diodes 31 which is introduced into the glass bulb 20, wherein the light-emitting diodes 31 including the circuit board 32 are embedded in a conversion material 34. The outer connection region 42 of the connectors of the light-emitting diodes 31 is embedded in a first housing 26. The first housing 26 can be formed, for example, with a plastic material and can be designed to be electrically insulating. For example, the outer connection region 42 is mechanically and/or electrically protected by the first housing 26. Furthermore, a second housing 27 can be present which can surround the fusion region 40 of the connectors.

(17) A possible wiring of the light-emitting diodes 31 of the light fixture 11 of FIG. 3A to one another is illustrated in FIG. 3B. The light-emitting diodes 31 are attached to a circuit board 32, which can also be a printed circuit board. In each case a group of light-emitting diodes 31 is series-connected to wirings 33, for example in the form of bonding wires and/or conductive tracks. Purely by way of example, in FIG. 3B in each case three light-emitting diodes 31 are connected to one another in series. The wirings 33 are connected to electrical contacts 331 by means of outer conductive tracks 332.

(18) A further exemplary embodiment of a light fixture 10 of a LED lamp 100 described here is explained in greater detail with reference to the representation in FIG. 4. In this case a holder for the light-emitting diodes 31 of the light fixture 10 according to FIGS. 1 and 2 are illustrated in detail. The light-emitting diodes 31 are part of LED filaments 30 which are arranged on an outer lateral surface of a cylindrical glass support 25. The LED filaments 30 are electrically conductively connected to one another by means of wiring 33. This facilitates common contacting of the LED filaments 30 to the inner connection regions 41.

(19) An exemplary embodiment of an LED lamp 100 described here is explained in greater detail with reference to the representation in FIG. 5. The LED lamp 100 is an LED retrofit lamp. The LED lamp 100 comprises a glass shell 60, a socket 61, a mounting base 62 and a light fixture 10. The socket can be an E27 or an E14 socket. The glass shell 60 is connected by means of the mounting base 62 to the socket 61.

(20) In the exemplary embodiment of FIG. 5, the light fixture 10 is constructed with LED filaments 30. The light fixture 10 is inserted into the mounting base 62 by the mounting region 21. The connectors 40, 41, 42 (not shown in FIG. 5) are electrically conductively connected to the socket 61 by the mounting base 62. The light fixture 10 is surrounded by the glass shell 60.

(21) A heat-conducting gas is located in the intermediate space 63 between the glass shell 60 and the light fixture 10, wherein the pressure of the heat-conducting gas in the intermediate space 63 is lower than in the glass bulb 20 of the light fixture 10. In order to maintain the pressure in the glass shell 60, the glass shell is preferably vacuum sealed.

(22) A further exemplary embodiment of a light fixture 10 of a LED lamp 100 described here is explained in greater detail with reference to the representation in FIG. 6. This shows a circuit board 32 with light-emitting diodes 31 which are provided for arrangement in the interior space of the light fixture 10. The circuit board 32 comprises holders 36 which serve for mechanical and/or electrical connection to further circuit boards 32. In this way several circuit boards 32 can be arranged relative to one another and a large solid angle can be covered by the light-emitting diodes 31. As an example, in FIG. 6 three circuit boards 32 are illustrated which are arranged on the lateral surfaces of a straight prism with a base surface of an equilateral triangle. However, arrangements of more circuit boards 32 are also conceivable, wherein the holders 36 are in each case bent corresponding to the required angle between the circuit boards 32. In the exemplary embodiment according to FIG. 6 the angle between the circuit boards 32 is 60 within the range of production tolerance.

(23) One of the circuit boards 32 has contact regions 35 which are connected to the inner connection regions 41 and the fusion region 40. The light-emitting diodes 31 of the other circuit boards 32 can be contacted by means of the holders 36.

(24) An exemplary embodiment of an LED lamp 100 described here is explained in greater detail with reference to the representation in FIG. 7. In contrast to the LED lamp according to FIG. 5 the illustrated LED lamp 100 contains a light fixture 10 with a matte glass bulb 20. Due to the matting of the glass bulb 20 the light-emitting diodes 31 in the glass bulb 20 can be concealed and an aesthetic visual appearance of the LED lamp 100 can be improved. In particular, in the case of a light-emitting diode 31 attached to a circuit board 32, the glass bulb 20 can be matte since wiring on the circuit board 32 can be concealed thereby.

(25) Different embodiments of light-emitting diodes 31 for a light fixture 10 described here are explained in greater detail with reference to the schematic illustrations in FIGS. 8, 9A and 9B.

(26) The light-emitting diode 31 according to FIG. 8 is constructed as a volume emitter. The light-emitting diode 31 can contain a substrate 312 which is, in particular, transparent to radiation and on which the radiation-emitting semiconductor layers of the light-emitting diode 31 are placed. The semiconductor layers can be covered with a conversion material 34 constructed as a fluorescent layer.

(27) In FIGS. 9A and 9B the light-emitting diodes 31 are in each case mounted on a circuit board 32, wherein the light-emitting diodes 31 can be connected to one another by means of wiring 33. In the exemplary embodiment according to FIG. 9A, a light-emitting diode 31 is uniquely associated with each circuit board 32. The wirings 33 are constructed as metal platings which are fitted in connection regions of the circuit boards 32. The number of required light-emitting diodes 31 is easily scalable in this embodiment, since in each case only individual circuit boards 32 have to be added or removed and it is not necessary for the entire wiring and/or circuit board size to be redesigned.

(28) In the exemplary embodiment according to FIG. 9B several light-emitting diodes 31 are mounted on one single circuit board 32. The wirings 33 are constructed as conductive tracks on the circuit board 32. An advantage of this embodiment, in particular, is that many light-emitting diodes 31 are provided on a small space.

(29) The fusion of the glass bulb 20 of a light fixture 10 described here with the connectors 40, 41, 42 of the light fixture 10 is explained in greater detail with reference to the illustrations in FIGS. 10A and 10B. In this case FIG. 10A shows a front view of a part of the light fixture 10 and FIG. 10B shows a rear view. It shows the inner connection regions 41 and the fusion regions 40 of the connectors. Purely by way of example the light-emitting diodes 31 of the light fixture 10 are mounted on a circuit board 32.

(30) The connectors 40, 41, 42 include a wire which extends outwards from an interior space of the glass bulb 20. In the fusion region 40 the glass material of the glass bulb 20 in the molten state has been squeezed or compressed, so that the wire is completely surrounded by glass and thus is melted into the glass. This enables airtight sealing of the glass bulb 20. A film for fusion with the glass material of the glass bulb 20 can also be mounted between the wire and/or instead of the wire in the fusion region 40.

(31) The wire can be made from not only molybdenum or tungsten but also a getter material such as for example tantalum. Typically, however, molybdenum is used and can be coated with a getter material (for example ZrAl).

(32) The wire can be bent double in the first connection region 41. As a result, it is possible for a contact region 35 on the front side and on the rear side of the circuit board 32 to be electrically conductively connected to the wire. In other words, the first connection region 41 can be in direct contact with a front side and a rear side of the circuit board 32. A better electrical power supply is guaranteed by such a contact. Moreover, due to this solution purely by clamping it is possible to dispense with soldering. Moreover, the light-emitting diodes 31 can be contacted more or less concurrently on the front side and on the rear side. Thus, in the event of a defect of one of the light-emitting diodes 31 on the front side or on the rear side the side without the defect can continue to light.

(33) The fusion of the glass bulb 20 of a light fixture 10 described here with the connectors 40, 41, 42 of the light fixture 10 is explained in greater detail with reference to the illustrations in FIGS. 11A, 11B, 12A, 12B, 13A and 13B. FIGS. 11A, 12A and 13A in each case show fusion when quartz glass is used as material for the glass bulb 20. FIGS. 11B, 12B and 13B in each case show fusion when tempered glass, such as for example borosilicate glass, aluminosilicate glass and/or Duran glass, is used as material for the glass bulb 20. In this case present FIGS. 12A, 12B, 13A and 13B in each case show alternative light fixtures 10, which differ from the light fixtures 10 described here in that instead of light-emitting diodes 31 a glow wire 51 is used as luminaire. However, in the light fixture 10 described here the fusion in the region of the mounting region 21 or fusion region 40 corresponds to that of the alternative light fixture 10. Thus, the features of the fusion region 40 described in connection with the alternative light fixtures 10 should be regarded explicitly as exemplary embodiments belonging to the invention.

(34) In the case of quartz glass lamps the fusion region 40 contains a film which in particular can be a molybdenum film. In contrast to this, in the case of tempered glass lamps the wire current supplies of the connectors 40, 41, 42 are directly melt-connected. In the case of tempered glass lamps the wire in the connection region 40 can likewise be formed with molybdenum. Alternatively, a wire with an iron-nickel-cobalt alloy and/or a tungsten wire can be used.

(35) Generally molybdenum-glass compounds are only possible as wire melt connection if the coefficients of thermal expansion differ by less than approximately 10%, for example in the case of tempered glasses. For example, quartz glass has a coefficient of thermal expansion of 0.6*10.sup.6 K.sup.1, molybdenum has a coefficient of thermal expansion of 5.1*10.sup.6 K.sup.1 and tempered glass has a coefficient of thermal expansion of 4.7*10.sup.6 K.sup.1. By the use of a molybdenum film and/or transition glasses in the fusion region 40 the difference in the coefficients of thermal expansion can be compensated for and a melt splice can be provided between the connectors 40, 41, 42 and the glass bulb 20.

(36) Exemplary embodiments of a light fixture 10 described here, as well as LED lamps 100 described here, are explained in greater detail with reference to the illustrations in FIGS. 14A, 14B and 14C. The drawings in each case show alternative lamps 100 with alternative light fixtures 10, in which instead of light-emitting diodes 31 a glow wire is used as luminaire. However, the other components of the alternative lamps 100 correspond to those of the LED lamps 100 described here. In other words, it is merely necessary to replace the glow wires with light-emitting diodes 31 in order to provide an LED lamp 100 described here. Thus, the features described in connection with the alternative lamps 100 should be regarded explicitly as exemplary embodiments belonging to the invention.

(37) The alternate lamps 100 in each case comprise a glass shell 60, an alternative light fixture 10 as well as a socket 61. Furthermore, a mounting base 62 can be provided. The glass shell 60 can be pear-shaped (FIGS. 14A and 14B). Alternatively, the glass shell 60 can be cylindrical (FIG. 14C). The light fixture 10 can be constructed in the manner of a halogen lamp with a pin base (FIG. 14A). However, the glass bulb 20 can also be elliptical or ellipsoidal or spherical (FIGS. 14B and 14C). The advantage of such a shape lies in the greater volume in the glass bulb 20, so that the convection inside the glass bulb 20 is further improved.

(38) A mode of operation of a light fixture 10 described here or of the LED lamp 100 described here is explained in greater detail with reference to the diagrams in FIGS. 15A and 15B. FIG. 15A shows a thermal output P in Watts from a luminaire arranged in the glass bulb 20 as a function of the pressure of the heat-conducting gas p (in mbar) in the glass bulb 20. In this case four different measurement curves for different heat-conducting gases are shown: nitrogen 81, argon 82, krypton 83 and xenon 84. As the filling pressure increases so also does the heat dissipation by the heat-removing gas.

(39) FIG. 15B shows a filling gas loss in arbitrary units as a function of the pressure in the glass bulb 20 for helium 91, krypton 93 and xenon 94. In a first pressure range 901 below a bend point 90 at approximately 1000 mbar the pressure in the glass bulb 20 is so low that only gas diffusion is observed and no convection. In a second pressure range 902 above the bend point 90 the luminaire in the glass bulb 20 is cooled by means of convection. The third pressure range 903 corresponds to the filling pressure range of conventional halogen lamps and preferably the pressure range of the heat-conducting gas in the glass bulb 20 of a light fixture 10 described here.

(40) The present application claims the priority of DE 10 2016 122 228.3, the disclosure of which is incorporated completely herein by reference.

(41) The invention is not limited to these embodiments by the description with reference to the exemplary embodiments. On the contrary, the invention encompasses each new feature as well as any combination of features, in particular including any combination of features in the claims, even if this feature or this combination itself is not explicitly given in the claims or the exemplary embodiments.

LIST OF REFERENCES

(42) 10 light fixture 20 glass bulb 21 mounting region 22 extension 25 glass support 26 first housing 27 second housing 30 LED filament 31 light-emitting diode 32 circuit board 33 wiring 331 electrical contacts 332 conductive track 34 conversion material 35 contact region 36 holder 40 fusion region 41 inner connection region 42 outer connection region 51 glow wire 60 glass shell 61 socket 62 mounting base 63 intermediate space 81 thermal output for nitrogen 82 thermal output for argon 83 thermal output for krypton 84 thermal output for xenon 90 bend point 91 filling gas loss for helium 93 filling gas loss for krypton 94 filling gas loss for xenon 901 first pressure range 902 second pressure range 903 third pressure range 100 LED lamp