EP2339223B1

EP2339223B1 - LED Bulb

Info

Publication number: EP2339223B1
Application number: EP09180550.7A
Authority: EP
Inventors: Michael Pauli
Original assignee: Novabase Digital TV Technologies GmbH
Current assignee: Novabase Digital TV Technologies GmbH
Priority date: 2009-12-23
Filing date: 2009-12-23
Publication date: 2014-05-14
Anticipated expiration: 2029-12-23
Also published as: EP2339223A1

Description

Field of the Invention

The present invention relates to an illuminant device, and in particular to an illuminant device providing for the possibility of energy-saving and of a flexible illuminant device.

Background of the Invention

In the recent years, there had been an upcoming demand for energy-saving illuminant devices, in particular for home use. To overcome the recycling problems of gas discharge lamps, an increasing number of illuminant devices are based on LED-technology, having less problems with recycling and at the same time a longer lifecycle. Such LED-based illuminant devices have a plurality of discrete LEDs, for example 10 or 30 LEDs, so that for a user such LED lamps appear totally different with respect to traditional bulbs. Further, as the LEDs are mounted on a rigid printed circuit board, such LED lamps can only be used as spots.
From US 2008/0225523 A1 , it is known to attach LEDs on top of pads, wherein a mounting layer may be a flexible layer. However, this flexible layer only allows a one-dimensional bending, so that the layer can be bended, but not be brought into a form, having an outer shape, the user is used to see.
From W02005/090852 a light emitting element is known using electronically activated light emitting elements, where a plurality of LED are arranged on a substrate.

Summary of the Invention

It may be seen as an object of the present invention to provide an illuminant device based on LED-technology, which has an outer appearance, the user is used to see while maintaining advanced illumination properties.
The object of the present invention is solved by the subject matter of the independent claims, wherein advantageous embodiments are incorporated in the dependent claims.
According to the invention, there is provided an illuminant device comprising a flexible substrate, a plurality of LED-dies, a light-transmissive hollow body having an inner surface, wherein the LED-dies are die-attached to the flexible substrate, wherein the flexible substrate has an outer shape such that the flexible substrate can be spatially bended in at least two directions and wherein the spatially bended flexible substrate follows a shape of the inner surface of the light-transmissive hollow body.
Thus, an illuminant device can be provided, which can be brought into an outer shape having an appearance, the user is used to see, and which has at the same time not a spot character, but a more or less uniform radiation characteristic over a large dihedral angle.
According to an exemplary embodiment of the invention, the flexible substrate of the illuminant device comprises terminals, wherein the LED-dies are connected to the terminals via printed circuit board tracks.
Thus, it is possible to have discrete terminal points over the flexible substrate to contact each of the LED dies. The printed circuit board tracks for this purpose are in the same way flexible as the flexible substrate.
According to an exemplary embodiment of the invention, the light-transmissive hollow body of the illuminant device is translucent.
This allows giving the illuminant device an outer appearance, having an almost uniform light density, so that the user substantially cannot distinguish the illuminant device from a traditional light bulb with respect to the outer appearance.
According to an exemplary embodiment of the invention, the light-transmissive hollow body of the illuminant device is made of plastic.
This allows providing a safe device, which is stable and insensitive over shocks and dropping to the bottom.
According to an exemplary embodiment of the invention, the light-transmissive hollow body of the illuminant device has a shape of a bulb.
Thus, the illuminant device can have almost the same appearance as a traditional light bulb, which is of advantage, when using a decorative luster, for which the used light bulb is an essential design or illumination aspect.
According to an exemplary embodiment of the invention, the flexible substrate of the illuminant device has planar convexities in form of at least one tongue.
Thus, in particular when providing a plurality of tongues, those tongues can be bended so as to follow a shape of the inner surface of the light-transmissive hollow body.
According to an exemplary embodiment of the invention, the flexible substrate of the illuminant device has a cutting geometry comprising a plurality of slits so as to allow a bending along a convex surface.
In particular, the slits can be provided in a displaced or offset manner, so as to allow a kind of stretching of the flexible substrate, which allows a flexibility to form a shape of the flexible substrate.
According to the invention, the plurality of LED-dies of the illuminant device are distributed over the flexible substrate such that when bendingly aligned to the inner surface of the light-transmissive hollow body an illumination density on an outer surface of the light-transmissive hollow body for at least a part of the outer surface is almost constant.
In particular, this can be obtained by varying the lateral distance between the LED-dies on the flexible substrate depending on the distance to the inner surface of the light-transmissive hollow body. Thus, even if the distance between the surface of the flexible substrate and the inner surface of the light-transmissive hollow body is not constant, the outer appearance of an almost constant illumination density can be achieved.
According to an exemplary embodiment of the invention, the illuminant device comprises a socket of a common illuminant system.
Thus, it is possible for the user to put the illuminant device into an already available standard socket of already existing lamps or luminaires.
According to an exemplary embodiment of the invention, the illuminant device further comprises a power supply device for providing the LED-dies with electric energy.
Thus, it is possible to use the illuminant device in a standard socket in a home available energy grid without the need for an external transformer or separate power supply device.
According to an exemplary embodiment of the invention, the LED-dies of the illuminant device are die-attached to both sides of the flexible substrate.
Thus, it is possible, in particular in combination with a complex substrate structure, to apply the substrate to a convex surface without the need to pay attention on the outward direction of the LED-dies when aligning the flexible substrate to the inner surface of the light-transmissive hollow body. This may be of relevance if the substrate portions tend to twist when being aligned.
According to an exemplary embodiment of the invention, each of the LED-dies of the illuminant device has a first contact and a second contact, wherein the first contact of each LED-die is connected to a printed circuit board track on a first side of the flexible substrate and the second contact of each LED-die is connected to a printed circuit board track on a second side of the flexible substrate.
This allows providing a very simple contacting of the flexible substrate, as the flexible substrate can be clamped between two counter-contacts in order to provide the energy supply for the flexible substrate. Further, a plurality of flexible substrates with die-attached LED-dies can be put together with a simple contacting mechanism, and without having to take care on the correct contacting of the terminals.
According to an exemplary embodiment of the invention, the printed circuit board tracks of the illuminant device are flexible in its longitudinal direction.
This allows providing a flexible substrate, which has certain elasticity along the flat extension, which allows a high flexibility for applying the flexible substrate to convex surfaces. Flexible circuit board tracks can be achieved by for example mixing a polymer material or a rubber material with a conductive additive or as an alternative by providing the printed circuit board tracks by a high-ductile metal material.
According to an exemplary embodiment of the invention, the illuminant device further comprises a receiver for remote control signals and a control unit wherein the control unit is adapted to control the LED-dies according to received remote control signals.
This allows the user to remote-control the entire illuminant device. This is advantageous, if for example putting more than one illuminant device to a luminaire or luster so as to control the separate illuminant devices separately, without the need for separate switches in the installed home electricity grid. This is of advantage in particular when being combined with the standard socket of a common illuminant system.
According to an exemplary embodiment of the invention, the LED-dies of the illuminant device are divided into a plurality of subgroups each being separately controllable by a control unit.
This allows the user to control the separate subgroups at its own or supported by an assistance system, so as to select for example a varying color composition. This can be achieved in particular when the different subgroups have different colors, so that a different controlling of the different subgroups allows changing a color of the illuminant device.
It should be noted that the above features may also be combined, and that the combination of the above features may also lead to a synergetic effect, even if not explicitly described in detail.
These and other aspects of the present invention will become apparent from and be elucidated with reference to the embodiments described hereinafter.

Brief Description of the Drawings

Exemplary embodiments of the present invention will be described in the following with reference to the following drawings.

Fig. 1 illustrates a schematic structure of an illuminant device according to an exemplary embodiment of the invention.
Fig. 2 illustrates a further exemplary embodiment of the illuminant device according to the present invention.
Fig. 3 illustrates a cutting shape of a flexible substrate according to an exemplary embodiment of the invention.
Fig. 4 illustrates an alternative cutting shape of the flexible substrate according to an exemplary embodiment of the invention.
Fig. 5 illustrates a sectional view of a flexible substrate with die-attached LED-dies with respect to a light-transmissive hollow body having a varying distance from the flexible substrate.
Fig. 6 illustrates an illuminant device with a standard socket according to an exemplary embodiment of the invention.
Fig. 7 illustrates a sectional view of the flexible substrate with die-attached LED-dies on both surfaces of the flexible substrate according to an exemplary embodiment of the invention.
Fig. 8 illustrates a three-dimensional view of die-attached LED-dies with a corresponding connecting geometry according to an exemplary embodiment of the invention.
Fig. 9 illustrates a flexible substrate with LED-dies and a plurality of terminals and printed circuit board tracks connecting the LED-dies with the respective terminals.
Fig. 10 illustrates a schematic view on an illuminant device according to an exemplary embodiment with grouped contact terminals according to an exemplary embodiment of the invention.

Detailed Description of Exemplary Embodiments

Fig. 1 illustrates a schematic view of an illuminant device according to the present invention. The illuminant device comprises a flexible substrate 10 and a plurality of LED-dies 20, which LED-dies 20 are die-attached to the flexible substrate 10. The flexible substrate is designed so as to form the inner surface 31 of a light-transmissive hollow body 30, so as to achieve an almost uniform light density over a wide dihedral or spatial angle so as to overcome the problem of only a spotted irradiation of light. The flexible substrate 10 can be designed as an elastic material, which can be for example provided with the die-attached LED-dies 20 when being brought into a flat position, and then being bended or generally formed so as to be aligned to the inner surface 31 of the light-transmissive hollow body 30. The flexible substrate 10 can be bended into at least two directions X, Y so as to be aligned to an e.g. spherical form of an illuminant device.
Fig. 2 illustrates a further exemplary embodiment of the invention, wherein the flexible substrate is again bended in the two directions X and Y, wherein the flexible substrate in the embodiment of Fig. 2 does not have to be elastic in the flat extension, but has to be only bendable in the at least two directions. Such a flexible substrate can have a shape as shown in Fig. 3 and as described later on. The flexible substrate 10 may have a plurality of tongues 13, which may form segments of the substrate. The substrate can be provided with distance pieces 12, which can be integrally formed with the substrate and can be for example folded outwardly to form a distance piece to keep a distance to the inner surface 31 of the light-transmissive hollow body 30. The flexible substrate can also be provided with a plurality of terminals 14, 15, which allow a contacting of the LED-dies being attached to the flexible substrate. This contacting can be carried out via printed circuit board tracks, which are not shown in Fig. 2. These printed circuit board tracks can be on the same side as the die-attached LED-dies 20, but can also be provided on the backside of the flexible substrate.
Fig. 3 illustrates a possible cutting shape of the flexible substrate in a planar projection, wherein the flexible substrate 10 can be provided with a plurality of tongues 13, the number of which is four in Fig. 3. At the same time, distance pieces 12 can be provided at the edge of the flexible substrate, wherein these distance pieces can be separately formed or integrally formed. When forming the distance pieces integrally to the flexible substrate, the distance pieces can be manufactured in the same cutting step and then folded outwardly to provide a distance to the inner surface of the light-transmissive hollow body, as shown in Fig. 2.
The flexible substrate can be provided with a plurality of terminals 14, 15, 16, 17, wherein the terminals can be provided for example at the end of the tongues 13, but can also be provided at the center of the flexible substrate. It should be noted, that also a plurality of terminals can be provided over the entire flexible substrate in order to provide a plurality of supply points in order to keep the distance of the printed circuit board tracks short. The flexible substrate can be provided with die-attached LED-dies 20, which are shown exemplarily for only one tongue in combination with the contacting circuit board tracks 19. It should be noted, that also for the remaining tongues a similar structure can be provided. It should also be noted, that the plurality of LED-dies are only shown for illustrative purposes, and that the actually used number of LED-dies may be much larger. For an illuminant device, for example thousands and ten thousands or more LED-dies can be used to provide a uniform light density over the entire flexible substrate. Such flexible substrate with the die-attached LED-dies can be manufactured for example by using semiconductor die-attaching machines, which are commonly used for manufacturing electronic devices. The tongues 13 can be bended into the two directions X and Y so as to form a three-dimensional surface, which can be aligned to the inner surface 31 of a light-transmissive hollow body 30.
Fig. 4 illustrates an alternative cutting geometry of the flexible substrate 10, onto which a plurality of LED-dies 20 is attached. This cutting geometry includes a plurality of slits 18, wherein these slits are for example offset or displaced to each other so as to form a cutting geometry allowing to expand the flexible substrate. The principle can be seen from the small illustration of Fig. 4. This kind of cutting geometry allows to flexibly mantel the substrate onto e.g. a carrier body, so as to form an illumination cover. It should be noted, that the slits can be very short and narrow, so that for the user, this geometry may not be visible when being provided in the illuminant device. It should be noted, that in Fig. 4 only a particular range of the flexible substrate is illustrated with the die-attached LED-dies 20, however, it should be understood, that the entire substrate can be provided with the die-attached LED-dies. For illustrative purposes, the illustration of the printed circuit board tracks and the terminals as well as the contacting is left out in Fig. 4.
Fig. 5 illustrates a sectional view of the flexible substrate 10 with die-attached LED-dies 20 in relation to an inner surface 31 of the light transmissive hollow body. If for example the distance between the surface of the flexible substrate 10 and the inner surface 31 of the light-transmissive hollow body 30 is not constant, the lateral distance of the LED-dies 20 on the surface of the substrate 10 can be varied, so as to achieve an appearance of an almost constant illumination density on the outer surface 32 of the light-transmissive hollow body.
Fig. 6 illustrates an illumination device according to an exemplary embodiment of the invention, wherein the illumination device is provided with a standard socket 40, which can be used in a commonly used light socket system. This can be for example an E27-socket or E14-socket, however, is not limited thereto. In the embodiment shown in Fig. 6, the illumination device 1 further comprises a power supply device 50 for providing the LED-dies 20 with electric energy. Further, the illumination device may include a receiver 60 for receiving remote control signals and a control unit 70, so that it is possible to control the LED-dies based on the received remote control signals. It should be noted, that the power supply 50, the receiver 60, and the control unit 70 can be provided in a single unit. Such devices or unit can be provided for example in the socket 40 of the illuminant device 1.
Fig. 7 illustrates a sectional view of the substrate 10, wherein the substrate 10 is provided with LED-dies 20 on both sides 11a and 11b of the substrate. In the embodiment shown in Fig. 7, each LED-die has two contacts 21 and 22, wherein the first contact 21 is contacted to the first side 11a of the substrate 10, wherein the second contact 22 is contacted to the second side 11b of the flexible substrate 10. For this purpose, the flexible substrate 10 can be provided with printed circuit board tracks 19, onto which the contacts 21 and 22 are connected by for example a wire-bonding process.
Fig. 8 illustrates a perspective view of the flexible substrate 10, wherein the LED-dies 20 are provided only on one side 11a of the flexible substrate 10, wherein the other side 11b of the flexible substrate is only provided with the contacts of the LED-dies and the printed circuit board tracks 19. It should be noted, that the printed circuit board tracks can be designed as a flat structure with recesses for the LED-dies, however, can also be provided with tracked paths, although not shown. It should also be noted, that the LED-dies can also be provided and attached directly onto a conductive layer, in order to simplify the contacting of the LED-dies.
Fig. 9 illustrates a flexible substrate 10 with a plurality of printed circuit board tracks 19, which tracks connect each of the plurality of LED-dies 20 being die-attached onto the surface of the flexible substrate 10. The LED-dies 20 can be divided into a plurality of subgroups A, B, C, D, in order to control the different subgroups separately. This can be for example useful when the different subgroups A, B, C, D have for example different colors, so that by separately controlling the subgroups A, B, C, and D, almost every desired color can be achieved. These different subgroups can be for example contacted via different terminals 14, 15, 16, 17, so as to provide the respective LED-dies 20 with respective control signals of a control unit, which is not shown in Fig. 9.
Fig. 10 illustrates a further exemplary embodiment of the invention, wherein the flexible substrate is provided with a plurality of contacts 14, which are distributed over the flexible substrate. Thus, the effective path length of the printed circuit board tracks can be kept low in order to keep the required energy low. The several contact terminals 14 can be provided with a contacting system having for example a larger cross-sectional diameter than for example the printed circuit board tracks, so as to keep the ohmic resistance low, which increases the efficiency of the illuminant device.
It should be noted that the term "comprising" does not exclude other elements or steps and that the "a" or "an" does not exclude a plurality. Also elements described in association with the different embodiments may be combined.
It should be noted that the reference signs in the claims shall not be construed as limiting the scope of the claims.

Claims

Illuminant device comprising:
a flexible substrate (10);

a plurality of LED-dies (20);

a light-transmissive hollow body (30) having an inner surface (31);

wherein the LED dies are die-attached to the flexible substrate;

wherein the flexible substrate has an outer shape (11) such that the flexible substrate can be spatially bended in at least two directions (X, Y), and

wherein the spatially bended flexible substrate follows a shape of the inner surface of the light-transmissive hollow body;

characterized in that the plurality of LED dies (20) are at non-constant distances between the flexible substrate (10) and the inner surface of the light-transmissive hollow body and are distributed over the flexible substrate (10) with a variation of a lateral distance of the LED dies, such that when being aligned to the inner surface of the light-transmissive body (30), a lumination density on an outer surface (32) of the light-transmissive hollow body for at least a part of the outer surface is almost constant.
Illuminant device according to claim 1, wherein the flexible substrate (10) comprises terminals (14, 15, 16, 17), wherein the LED dies (20) are connected to the terminals via printed circuit board tracks (19).
Illuminant device according to any of claims 1 and 2, wherein the light-transmissive hollow body (30) is translucent.
Illuminant device according to any of claims 1 to 3, wherein the light-transmissive hollow body (30) is made of plastic.
Illuminant device according to any of claims 1 to 4, wherein the light-transmissive hollow body (30) has a shape of a bulb.
Illuminant device according to any of claims 1 to 5, wherein the flexible substrate (10) has planar convexities (13) in form of at least one tongue.
Illuminant device according to any of claims 1 to 6, wherein the flexible substrate (10) has a cutting geometry comprising a plurality of slits (18) so as to allow a bending along a convex surface.
Illuminant device according to any of claims 1 to 7, further comprising a socket (40) of a common illuminant system.
Illuminant device according to any of claims 1 to 8, further comprising a power supply device (50) for providing the LED dies (20) with electric energy.
Illuminant device according to any of claims 1 to 9, wherein the LED dies (20) are die-attached to both sides (11a, 11b) of the flexible substrate (10).
Illuminant device according to any of claims 1 to 10, wherein each of the LED dies (20) has a first contact (21) and a second contact (22), wherein the first contact of each LED die is connected to a printed circuit board track (19) on a first side (11a) of the flexible substrate and the second contact of each LED die is connected to a printed circuit board track on a second side (11b) of the flexible substrate (10).
Illuminant device according to any of claims 2 or 11, wherein the printed circuit board tracks (19) are flexible in its longitudinal direction.
Illuminant device according to any of claims 1 to 12, further comprising a receiver (60) for remote control signals and a control unit (70), wherein the control unit is adapted to control the LED dies according to received remote control signals.
Illuminant device according to any of claims 1 to 13, wherein the LED dies (20) are divided into a plurality of subgroups (A, B, C, D) each being separately controllable by a control unit (70).