DE102017117521B4 - Lamp and method for producing a light bulb - Google Patents

Abstract

The invention relates to a luminous means (1), comprising a plurality of first light-emitting diodes (221) mounted on a support (31), which are accommodated in a housing (21), wherein the support (31) is flexible at least in some areas and is flexible A plurality of adhesive dots (32) on the housing (21) is attached.

Description

Technical area

The present invention relates to a luminous means and to a method for producing a luminous means.

Technical background

Illuminants for LED retrofit lamps may have a housing containing light-emitting diodes as light-emitting components. The light-emitting diodes are usually applied to a common printed circuit board. To attach the light-emitting diodes to the housing, the printed circuit board with the light-emitting diodes is glued into the housing by means of an adhesive layer applied over the whole surface. The adhesive used must then ensure the compensation of the different length expansions of the circuit board and the housing. These different length expansions lead to stresses in the materials of the housing and the printed circuit board, which can lead to a detachment of the printed circuit board and thus also of the LEDs from the housing.

From the US 2015/0176770 A1 is an LED lamp with a glued-in support or substrate known.

Presentation of the invention

Based on the technical background, it is an object of the present invention to provide a luminous means with an improved thermal expansion behavior and a method for producing such a luminous means.

The object is achieved by a luminous means and a method having the features of the independent claims. Advantageous developments emerge from the dependent claims, the description, the figures and the embodiments described in connection with the figures.

Accordingly, a light source is specified. The lighting means comprises a plurality of applied to a support first light-emitting diodes, which are accommodated in a housing, in particular in an interior of the housing. The carrier is at least partially flexible, in particular mechanically flexible, formed and secured by a plurality of adhesive dots on the housing.

By using individual adhesive dots instead of an adhesive layer applied over the entire surface in conjunction with an at least partially flexible support, stresses due to thermal expansion during operation of the luminous means can be compensated. Preferably, such thermal stresses can be eliminated in a region between the adhesive dots. In particular, this large free areas of the housing are free of an adhesive, which is why an adaptation to the thermal expansion coefficients of the existing components by means of the adhesive used is only conditionally necessary, preferably only in the region of the respective adhesive dots. It is possible that such an adjustment already takes place by an appropriate choice of the spatial dimensions of the adhesive dots. In comparison to a luminous means with an adhesive layer formed over the entire area, the position of the light-emitting diodes in the luminous means-and thus the optical properties of the luminous means-preferably does not change.

The light-emitting means in particular comprises a plurality of light-emitting diodes, wherein at least one part, preferably all, light-emitting diodes are each assigned a glue point as the first light-emitting diodes. The fact that a gluing diode is "assigned" to a gluing point can mean here and below that an adhesive point is arranged in the region and / or at a position of the light-emitting diode, that is to say in the vertical direction below the light-emitting diode. There may be other LEDs in the light source, such as second light emitting diodes, which no glue point is assigned. A light-emitting diode comprises at least one inorganic or organic light-emitting diode chip. During operation, the light-emitting diode emits electromagnetic radiation, preferably visible light, through a light exit surface of the light-emitting diode. The first light-emitting diodes, in particular all light-emitting diodes of the light-emitting means, are preferably connected to one another mechanically and / or electrically conductively.

In this application, the term "light emitting diode" without an addition such as "first" and "second", both the first light emitting diodes and optionally present second LEDs designate. By the term "all light-emitting diodes" is meant all light-emitting diodes of the light-emitting means which contribute to the generation of an electromagnetic radiation emitted by the light-emitting means, in particular of a light generated for illuminating a room. Further light-emitting diodes, which are present in a driver electronics and / or in the interior of the luminous means and / or merely serve as a status indicator, preferably do not belong to the light-emitting diodes enumerated here.

The carrier has a main extension plane into which it extends along lateral directions. Perpendicular to the main plane of extension, in a vertical direction, the carrier points a thickness that is small compared to the maximum extent of the carrier along the main plane of extension. The light-emitting diodes are applied to a mounting surface of the carrier facing away from the housing. The mounting surface preferably runs along the main extension plane. On a housing surface facing the bottom of the carrier are the adhesive dots.

The lighting means may comprise a single or a plurality of carriers, wherein a plurality of light-emitting diodes, in particular a plurality of first light-emitting diodes, is applied to each carrier. In particular, the carrier may be a flexible printed circuit board.

The carrier is at least partially flexible. By way of example, the carrier comprises first regions, which are designed to be flexible, and second regions, which are rigidly formed. Preferably, the carrier is completely flexible. The carrier is then formed only from first areas. It is also possible that the carrier in the unpopulated state, that is, without light-emitting diodes, is designed to be completely flexible and that the carrier in the assembled state in the region of the light-emitting diodes is rigid. In this case, the LEDs may have a mechanical stabilizing effect on the carrier, which is why this can be rigid in the field of light emitting diodes.

The fact that the carrier is "flexibly formed" may in this application in particular mean that the carrier is repeatedly, preferably at least 10 times and more preferably at least 100 times, up to a minimum bending radius, for example at least 1 mm and at most 20 mm, preferably 5 mm , may be mechanically non-destructive and / or reversible bendable. In contrast, with a rigid support, bending with a small bend radius may result in cracks and / or dislocations in the wearer's material. A rigid carrier is for example a metal plate and / or a ceramic.

The carrier comprises, for example, a multiplicity of films which are thermally welded together and / or laminated together. In particular, the carrier comprises at least one electrically insulating film which is formed, for example, with polyimide. To provide printed conductors, an electrically conductive film, such as a metallic film, may be laminated onto the insulating films, and the desired wiring pattern may be provided by an etching process. Alternatively or additionally, it is possible that the carrier is formed with a paper, for example a resin paper, wherein the conductor tracks can be printed on the paper.

The term "dot" in the sense of "glue dot" is not to be understood in this application according to the geometrically strict meaning. Rather, the adhesive point is preferably a contiguous, three-dimensional area. In other words, the glue point has non-zero, in particular finite, geometric dimensions in the vertical direction and in the lateral directions.

The glue dot is formed with an adhesive. The adhesive is preferably designed to be electrically insulating. For example, the adhesive point is a, in particular compressed and / or hardened, drops of the adhesive. The adhesive point is preferably attached to one of the light exit surface of the light emitting diode opposite bottom surface of the light emitting diode. Preferably, each glue point directly adjoins the carrier and / or the housing. Alternatively, a coating can be present between the adhesive dots and the housing, which is directly adjacent to the housing and the adhesive point. The coating can for example improve a light extraction from the housing and / or a thermal conductivity of the housing and / or an adhesion of the adhesive dots on the housing.

The glue dots are uniquely assigned to the first light emitting diodes. In other words, the number of adhesive dots in the luminous means corresponds to the number of first light-emitting diodes in the luminous means. Alternatively or additionally, each adhesive point is arranged in the vertical direction under each one of the first light-emitting diodes. In other words, the adhesive dots are located at the positions and / or in the region of the first light-emitting diodes. That is, along the vertical direction may be located between the first light emitting diodes and the housing each have a glue point. Preferably, the adhesive dots are not connected to each other.

In other words, the adhesive dots are formed separately from each other.

In accordance with at least one embodiment, the luminous means has a plurality of second light-emitting diodes connected to the first light-emitting diodes. The carrier is in the region of the second light emitting diodes each free of a glue dot. That is, along the vertical direction, there is no glue dot between the second light-emitting diodes and the housing. The second light emitting diodes may have the same structure and / or the same composition as the first light emitting diodes. In particular, the luminous means has a plurality of light-emitting diodes, with one part of the light-emitting diodes being assigned in each case one adhesive dot as the first light-emitting diodes and no other part of the light-emitting diodes as second light-emitting diodes Adhesive dot is assigned. This means that the carrier in the region of the second light emitting diodes is free of a glue dot and / or no glue dot is arranged in the vertical direction below the second light emitting diodes.

In accordance with at least one embodiment of the luminous means, a plurality of the second light-emitting diodes is arranged between two first light-emitting diodes. For example, exactly two second light-emitting diodes are arranged between two first light-emitting diodes. If the first light-emitting diodes and the second light-emitting diodes are arranged linearly in a row, the first light-emitting diodes, at whose position a gluing point is present, and the second light-emitting diodes, at whose position no gluing point is present, can alternate.

In accordance with at least one embodiment of the luminous means, the first light-emitting diodes and the optional second light-emitting diodes are arranged in a row. In particular, the LEDs are arranged linearly. That is, the light-emitting diodes are arranged in particular not matrix-like. The row of light-emitting diodes has a longitudinal axis and a transverse axis. Along the longitudinal axis all LEDs can be arranged. Along the transverse axis is preferably arranged at most one light emitting diode. Preferably, the row of light-emitting diodes extends along a main axis of extension of the housing. The longitudinal axis and the transverse axis preferably run along one of the lateral directions.

It is possible that the lighting means has only a single row of light-emitting diodes. In a preferred embodiment, the luminous means has a plurality of rows of light-emitting diodes which are each arranged along a longitudinal axis. The rows can have a maximum distance of 50 mm along the transverse axis. The rows can be arranged on a common carrier or arranged in each case on a separate carrier.

In accordance with at least one embodiment of the luminous means, each of the light-emitting diodes of the luminous means is associated with an adhesive point, in particular one-to-one. In other words, each light-emitting diode of the light-emitting means is a first light-emitting diode. In this embodiment, the luminous means is in particular free of second light-emitting diodes, to which no adhesive point is assigned.

In accordance with at least one embodiment of the luminous means, the carrier is fastened to an inner surface of the housing. At least one free area of the inner surface, in particular between the adhesive dots, is free of the material of the adhesive dots. In other words, the glue dots are not connected to each other. In particular, the free area of the inner surface is in the region between adjacent and / or successive first light-emitting diodes.

According to at least one embodiment of the luminous means, the housing is a light-transmitting tube. The tube is preferably cylindrical. For example, the housing is formed with glass or a plastic. The housing may be formed the same as the glass tube of a fluorescent tube. The light source can then be a LED retrofit lamp as a substitute for a fluorescent tube. The first light emitting diodes and the optional second light emitting diodes are arranged along a main direction of extension of the housing. In particular, the first light emitting diodes and the optional second light emitting diodes are arranged linearly in a row along the main extension direction. The longitudinal axis of the row then preferably runs along the main extension direction.

In accordance with at least one embodiment of the luminous means, the carrier has an expansion region between the first light-emitting diodes and the optionally present second light-emitting diodes. The expansion area is set up such that a thermal expansion and / or a thermally induced change in position of the first light emitting diodes and / or the optionally present second light emitting diodes along an expansion axis causes a non-destructive deformation of the expansion area along the expansion axis. In particular, the expansion region can be a first region of the carrier, which has a flexible design. The carrier may have a second region in the region of the light-emitting diodes. The second area may be flexible or rigid. In particular, it is possible for the second area to be stabilized by the light-emitting diodes and thus to be rigid.

In accordance with at least one embodiment of the luminous means, the support has at least one bend in the expansion region at room temperature and / or in the switched-off state of the luminous means. In particular, the support may have a single bend and / or a folded and / or a corrugated shape in the expansion region at room temperature and / or in the switched-off state. Preferably, the carrier between adjacent light-emitting diodes at room temperature and / or in the off state is arcuate.

The expansion area is based in particular on the following idea. Thermal expansion, in particular due to heating of the light source during operation of the light source can lead to a change in the distance between two light-emitting diodes and / or to a change in position of the light-emitting diodes. For a rigid support and / or a stretched flexible support, such thermal expansions could lead to interacting stresses between the individual adhesive spots. This can result in damage to the carrier and / or separation of the carrier from the housing. In order to absorb stresses due to thermal expansion, the carrier is preferably introduced into the housing in such a way that it can expand upon thermal expansion of the luminous means. In particular, the expansion area is provided for this purpose. In a preferred embodiment, the support is bent, wave-like and / or folded at room temperature and / or in the switched-off state of the luminous means in the expansion region located between the light-emitting diodes. The expansion area is in particular a thermal elimination arc.

In accordance with at least one embodiment of the luminous means, the adhesive dots are formed with a thermally conductive adhesive. For example, the adhesive is a silicone and / or a UV-activated adhesive. By means of a thermally conductive adhesive, the heat produced by the light-emitting diodes during operation can be efficiently dissipated to the housing. Preferably, the adhesive dots border directly on the housing for this purpose.

In accordance with at least one embodiment of the luminous means, the adhesive dots each have a thickness of at most 5 mm, preferably at most 3 mm and particularly preferably at most 1 mm. The thickness preferably runs along the vertical direction. In the lateral directions, the glue dot has a lateral extension. The geometric dimensions of the adhesive point along the lateral directions preferably deviate by at most +/- 100%, particularly preferably by at most +/- 20%, from the geometric dimensions of the first light-emitting diode associated with the adhesive point along the lateral directions.

In a conventional illuminant, a full-surface adhesive layer may have a thickness of more than 5 mm. Such a high thickness allows, for example, a thermal adaptation of the carrier and the housing by means of the adhesive layer. However, heat generated during operation of the lamp is poorly dissipated with a thick adhesive layer. In contrast, thin dots of adhesive can enable a reduction in the thermal resistance of the dots of adhesive, thereby efficiently dissipating the heat produced by the LEDs during operation.

Furthermore, a method for the production of a light source is specified. The method is preferably suitable for the production of a light source described here. That is, all features disclosed for the illuminant are also disclosed for the method, and vice versa.

Accordingly, a method for producing a luminous means is given. In a first method step, a plurality of adhesive dots are attached to a carrier. On the carrier a plurality of first light-emitting diodes is applied. The adhesive dots are preferably attached to a bottom surface of the carrier facing away from the first light-emitting diodes. The attachment is preferably carried out such that in each case a first light-emitting diode, a glue dot is uniquely associated and / or each glue point is arranged in a vertical direction under each one of the first light-emitting diodes. That is, the glue dot is attached to the position of the first light emitting diode on the bottom surface. In a further method step, which is preferably carried out after the first method step, the carrier is fastened by means of the adhesive dots to a housing. In particular, the carrier is introduced into an inner space of the housing and fastened to an inner surface of the housing.

When attaching the carrier, for example, be pressed onto the inner surface. Preferably, the glue point is present during fastening in the uncured, in particular in the liquid, state. After fixing, the adhesive of the adhesive point can be cured, for example by supplying ambient air and / or by means of UV radiation.

The adhesive point can be applied with a nozzle. Preferably, the nozzle is not moved during the application of the adhesive point to the carrier along the lateral directions of the carrier. The adhesive point can thereby be applied only in a small area of the carrier. A lateral extension of the adhesive point is obtained in this case, preferably due to a flow apart of the adhesive used.

list of figures

• Die 1A und 1B zeigen ein erstes Ausführungsbeispiel eines hier beschriebenen Leuchtmittels.
• Die 1A und 1B zeigen ein zweites Ausführungsbeispiel eines hier beschriebenen Leuchtmittels.

Preferred further embodiments of the invention are explained in more detail by the following description of the figures.

• The 1A and 1B show a first embodiment of a light bulb described here.
• The 1A and 1B show a second embodiment of a light bulb described here.

Detailed description of preferred embodiments

In the following, the luminous means described here and the method described here are explained in greater detail on the basis of exemplary embodiments and the associated figures. The same, similar, similar or equivalent elements are provided with the same reference numerals. A repeated description of these elements is partially omitted in order to avoid redundancies.

The figures and the proportions of the elements shown in the figures with each other are not to be considered to scale. Rather, individual elements may be exaggerated in size for better representability and / or better understanding.

Based on the schematic sectional views of 1A and 1B a first embodiment of a luminous means 1 described here is explained in more detail. The 1B shows an enlargement of a detail 100 of the 1A ,

The lighting means 1 comprises a housing 21 , which in the present case is a cylindrical glass tube. The housing 21 is at the ends of a lamp base 12 closed, the for electrical contacting of the bulb 1 serves.

In the case 21 are several first light-emitting diodes 221 and a carrier 31 brought in. The carrier 31 by means of several adhesive dots 32 on an inner surface 21a of the housing 21 attached. Every glue dot 32 is a first light emitting diode 221 uniquely assigned. In a region between adjacent first light-emitting diodes 221 has the inner surface 21a a free area 24 on, the free of the material of the adhesive dots 32 is.

The carrier 31 is flexible. Between the first light emitting diodes 221 instructs the wearer 31 an expansion area 311 in which the carrier 31 bent is formed. Because of this bend in the expansion area 311 can have different thermal expansion coefficients between the material of the carrier 31 and the material of the housing 21 be compensated.

In the first embodiment, the carrier bends 31 to the inner surface 21a of the housing 21 out. However, it is also possible that the carrier 31 in the expansion area 311 from the inner surface 21a of the housing 21 Bends away. Furthermore, the carrier can 31 in the expansion area 311 be formed folded and / or wavy.

Based on the schematic sectional views of 2A and 2 B a second embodiment of a light bulb 1 described here is explained in more detail. The 2 B shows an enlargement of a detail 100 of the 2A ,

In contrast to that in the 1A and 1B shown first embodiment, the lamp 1 now has a plurality of first light-emitting diodes 221 and a plurality of second light-emitting diodes 222 on. The second light-emitting diodes 222 is not a glue point 32 assigned. That is, in the range of the second light-emitting diodes 222 is the carrier 31 free from a glue dot 32 , In the area of the first light-emitting diodes 221 instructs the wearer 31 one glue dot each 32 on, by means of which the carrier 31 - And with it the first light-emitting diodes 221 and the second light emitting diodes 222 - with the housing 12 connected is. There are two second LEDs each 222 between two first LEDs 221 arranged. The first light-emitting diodes 221 and the second light emitting diodes 222 are together on the carrier 31 arranged.

The invention is not limited by the description based on the embodiments of these. Rather, the invention encompasses any novel feature as well as any combination of features, which in particular includes any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the patent claims or exemplary embodiments.

LIST OF REFERENCE NUMBERS

1

Lamp

12

lamp base

21

casing

21a

palm

221

first light-emitting diode

222

second light-emitting diode

24

outdoor Space

31

carrier

311

expansion area

100

neckline

Claims (12)

Lighting means (1) comprising a plurality of on a support (31) applied first light-emitting diodes (221) which are accommodated in a housing (21), wherein the carrier (31) is at least partially flexible and by means of a plurality of adhesive dots (32 ) is attached to the housing (21), wherein the adhesive dots (32) the first light-emitting diodes (221) are uniquely associated and / or each glue dot (32) is arranged in a vertical direction under each one of the first light-emitting diodes (221). The luminous means (1) according to one of the preceding claims, wherein the luminous means (1) has a plurality of second light-emitting diodes (222) applied to the carrier (31), wherein the carrier (31) is exposed in the region of the second light-emitting diodes (222) from a glue dot (32). Illuminant (1) according to the preceding claim, wherein a plurality of the second light emitting diodes (222) between two first light-emitting diodes (221) is arranged. Illuminant (1) according to one of the preceding claims, wherein the first light emitting diodes (221) and the optional second light emitting diodes (222) are arranged in a row. Illuminant (1) after one of the previous Claims 1 or 3 or 4 , wherein all light emitting diodes (221, 222) of the lighting means (1) is associated with a glue point (32). Illuminant (1) according to one of the preceding claims, wherein the carrier (31) are fastened to an inner surface (21a) of the housing (21) and at least one free area (24) of the inner surface (21a) is free from the material of the adhesive points (32). is. Illuminant (1) according to one of the preceding claims, wherein the housing (21) is a light-transmitting tube and the first light-emitting diodes (221) and optionally present second light-emitting diodes (222) along a main extension direction of the housing (21) are arranged. Illuminant (1) according to the preceding claim, wherein the carrier (31) between the first light-emitting diodes (221) and the optionally present second light emitting diodes (222) has an expansion region (311) which is arranged such that a thermal expansion and / or a thermally induced change in position of the first light-emitting diodes (221) and / or the optionally present second light-emitting diodes (222) along an expansion axis a non-destructive deformation of the expansion region (331) along the expansion axis conditionally. Illuminant (1) according to the preceding claim, wherein the support (31) in the expansion region (311) at room temperature and / or in the off state of the luminous means (1) has at least one bend. Illuminant (1) according to one of the preceding claims, wherein the adhesive dots (32) are formed with a thermally conductive adhesive. Illuminant (1) according to one of the preceding claims, wherein the adhesive dots (32) each have a thickness of at most 5 mm. Method for producing a luminous means (1), comprising the following steps: - Attaching a plurality of adhesive dots (32) on a support (31) on which a plurality of first light-emitting diodes (221) are applied; Fixing the carrier (31) to a housing (21) by means of the adhesive dots (32), wherein the adhesive dots (32) are uniquely associated with the first light emitting diodes (221) and / or each glue dot (32) in a vertical direction among each one the first light emitting diodes (221) is arranged.

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