DE102008005120A1 - LED module with a lens - Google Patents

Abstract

The invention relates to an LED module (1) comprising at least one carrier element (2), at least one light-emitting diode (LED) (4) arranged on the carrier element (2) and at least one lens (5) arranged in the beam path of the radiation emanating from the LED ). The LED module comprises at least one reflector (6) and one of the LED (4) facing the radiation entrance surface (10) of the lens (5) is spaced from the surface of the LED (4).

Description

Technical area

The The invention relates to an LED module comprising at least one carrier element, at least one on the carrier element arranged light emitting diode (LED) and at least one in the beam path the arranged from the LED radiation emitted lens.

LED chips For the most part, the generated radiation is relatively undirected. Therefore have LED modules in which one or more LED chips on a support element are arranged, usually an optical system to a defined Radiation behavior, as is for Lighting purposes desired is set.

In In its simplest form, this optical system consists of a Lens, usually on the LED chip is arranged. Often This lens is made of a polymer material, since so with simple Means inexpensive Even complex geometries can be realized.

It are also solutions known in which the optical system consists only of a reflector, which makes the beam shaping. To a sufficiently narrow beam angle However, a complicated reflector geometry is needed and The reflector has a very high height, which is why lens systems preferred become.

Directly However, lenses arranged on the LED chip are exposed to high temperatures. This can be especially for Polymer lenses to a deterioration of the optical properties and lead to a limitation of the life. With blue and white LEDs In addition there is a relatively high concentration of UV radiation on the lens, reducing the heat resistance most of the polymers further reduces and the aging of the lens is accelerated.

moreover By attaching the lens to the LED chip, the heat dissipation hampered by this.

Presentation of the invention

The The object of the present invention is to provide an LED module comprising at least a carrier element, at least one arranged on the carrier element Light emitting diode (LED) and at least one in the beam path of the LED outgoing radiation arranged lens, to create easy and inexpensive is produced and in which the thermal load of lens and LED chip is reduced.

These Task is solved in that the LED module comprises at least one reflector and one the LED facing radiation entrance surface of the lens from the surface of LED is arranged at a distance. The lens is thus no longer in direct contact with the LED and the thermal load of the components is sufficiently reduced, without the light output compared to the usual To reduce the lens arrangement excessively. Opposite the Using a reflector without a lens becomes a much more compact Construction allows, because the height of the reflector can be significantly reduced. In addition, over the Reflector be made a light mixture, the color inhomogeneities, the even when using white LEDs through areas with slightly different color temperature or color may arise reduced.

advantageously, At least two LEDs are in a preferably rectangular group summarized by LED. As a group of LEDs are under this Login viewed at least two LED chips, their spacing among themselves is less than the maximum linear dimension of each LED. The maximum linear dimension is the maximum distance between two on the outer contour view the LED points. The arrangement of LED in Allows groups it, big To realize light outputs on a small scale.

It is appropriate if one of the LED facing radiation entrance surface of the lens at a distance of at least 2.5 mm, preferably of at least 5 mm, to the surface the LED is arranged. With increasing distance decreases the thermal stress continues, which is why a distance of more than 5 mm opposite shorter distances is to be preferred.

According to one advantageous development of the invention is one of the LED facing Radiation entrance area the lens is arranged at a distance to the surface of the LED, the at least the maximum linear dimension, preferably at least 2 times the maximum linear dimension of the LED and / or a Group of LED matches. The maximum linear dimension is the maximum distance between two on the outer contour of the LED respectively to look at the group of LED points. By the arrangement according to the invention becomes un dependent from the absolute size of the LED likewise a sufficient distance between lens and LED attains to to ensure the function of the lens even in long-term operation.

Furthermore, it is advantageous if one of the LED facing radiation entrance surface of the lens is arranged at a distance from the surface of the LED, which corresponds to at least a quarter of the diameter of the radiation entrance surface of the lens, in particular at least one third of the diameter of the radiation entrance surface of the lens. This also ensures that the thermal stress of the lens is reliably reduced regardless of their absolute size and no heat build-up between the LED and the lens.

By doing the LED facing radiation entrance surface of the lens at a distance from at most 30 mm, preferably at most 20 mm from the surface The LED is arranged to ensure that the LED emitted radiation reaches the lens with as little loss and also a compact arrangement is achieved.

It is also advantageous if the LED facing radiation entrance surface of the Lens is arranged at a distance to the surface of the LED, the maximum 8 times the maximum linear dimension, preferably at most 5 times the maximum linear dimension of the LED and / or the Group of LEDs corresponds. Again, this ensures that, regardless of the absolute size of the LED or the group of LEDs emitted by the LED Radiation in sufficient concentration tion arrives at the lens and a compact construction is achieved.

Farther it is useful if the LED facing radiation entrance surface of the lens at a distance to the surface the LED is arranged at most 1.5 times the diameter of the radiation entrance surface of Lens, in particular at most corresponds to the diameter of the radiation entrance surface of the lens. Also This ensures a compact design with good light output.

advantageously, the lens is essentially formed of a polymer material. Polymer materials enable a simple and inexpensive Forming even with complex shapes, whereby the advantages of the Invention with these lenses particularly significant effect.

It is also advantageous if the reflector perpendicular to the LED Main radiation surrounds all sides. This will increase the light output and the efficiency increases, because all the light shone to the side in the direction of the lens or the emission direction can be concentrated.

Especially It is advantageous if the reflector, the arrangement of LED and Lens perpendicular to the main emission direction surrounds all sides. This will a particularly good light output and a homogeneous radiation behavior achieved.

In an appropriate training According to the invention, the lens is designed as a plano-convex lens. In order to let yourself advantageous to realize a relatively narrow beam angle of 10 ° to 30 °.

In another expedient development According to the invention, the lens is designed as a concave convex lens. Thereby can advantageously achieved a relatively wide beam angle of 30 ° to 60 ° become.

Farther it is advantageous if at least one surface of the lens is aspherical. aspheric Enable lenses a very homogeneous radiation characteristic.

advantageously, includes the edge of the lens with the optical axis an angle between 10 ° and 60 °, preferably between 20 ° and 50 °. These bevel prevents aberrations in the edge area of the lens in which otherwise a deflection of the beams in an unwanted direction take place would. In the preferred selected area For given lens dimensions as many as possible run from the LED outgoing rays undisturbed to the reflector.

Conveniently, The LED module includes several LEDs. This increases the luminosity and, if these are grouped together, a compact design achieved.

It is appropriate if the LED combined in a preferably rectangular group are. Such an arrangement allows a high light output to install in a small space.

It is advantageous if at least one fastener for attachment the lens on the support element is provided. This allows the lens to be stable and defined Distance to the also firmly connected to the support element LED be attached.

Farther it is useful if at least one fastening element for fastening the lens the reflector is provided. This also makes the lens safe held and made of lens and reflector an optical system with defined Properties formed, which may also be handled as such and in particular can be mounted.

One a particularly simple construction is achieved if at least one fastening element and the lens in one piece are formed. In addition, these can then manufactured and processed together, reflecting the manufacturing process simplified the module.

Farther it is useful if the fastener at least one snap connection for connection having the reflector and / or the carrier element. Thereby can easily connect and thus the Manufacturing costs for the LED module can be reduced.

It is advantageous if the reflector has several annular segments includes. As segments are those areas of the reflector viewed in the direction of radiation, within which the Krömmungsrichtung in a section plane containing the optical axis of the reflector remains the same, the segments by a change in the direction of curvature or a sudden change the curvature are delimited from each other. Due to the segmentation, the radiation behavior be influenced advantageous because the individual ring segments each can reflect in different directions. This is special also useful to a better Farbhomogeni ity with LED or groups of LED with areas of different color or color temperature.

It is also advantageous if at least one segment of the reflector at least 6, preferably between 10 and 14, in particular 12 facets having. The faceting causes a further homogenization the color distribution, since so the pictures of different Areas of an LED chip or different LED of a group of Overlap LED.

Farther it is useful if the reflector essentially of a thermally well-conducting Material, in particular aluminum, is formed. This allows the Reflector in addition for heat dissipation the LED can be used and

Short description of the drawing (s)

in the Below, the invention will be explained in more detail with reference to an embodiment. The Figure shows an inventive LED module in a side sectional view.

Preferred embodiment of invention

The LED module 1 essentially comprises a carrier plate 2 , on the invention, a group 3 of light emitting diodes (LED) 4 , as well as a lens 5 and a reflector 6 are arranged. The center of the group 3 of light emitting diodes 4 is as well as the central axis of the lens 5 and the center axis of the reflector 6 on the optical axis A of the overall system.

The carrier element 2 is in the present embodiment as a printed circuit board 2 executed, on which a group 3 of a total of six LED chips 4 is located. These are in two rows of three rectangular single chips each 4 arranged so that there is a rectangular overall arrangement with an edge length of about 3 mm in the longitudinal direction and about 2 mm in the transverse direction. The considered light-emitting diodes 4 emit radiation in the visible light range.

The Lens 5 is made of a transparent polymer material according to the prior art and at a distance of approximately 8 mm from the group 3 of light emitting diodes 4 via fasteners 7 with the carrier element 2 connected. The distance of the lens 5 by the group 3 from LED 4 is thus more than twice the maximum linear dimension of the group 3 from LED 4 , which in this case is the diagonal of the rectangular arrangement of about 3.6 mm. Too large a distance of the lens 5 from the LED 4 should be avoided, because that is the thermal load of the lens 5 continues to sink, but the arrangement then becomes very large. A maximum distance of 20 mm or approximately 5 times the maximum linear extent of the group 3 from LED 4 has proven to be useful in the commonly used components. The fasteners 7 have at their pcb side end snap tabs 8th on that in drilling 9 in the carrier element 2 engage and so create a snap connection.

The Lens 5 has a diameter of approximately 17 mm and is designed as aspherical plano-convex lens, which allows a narrow beam angle of about 20 °. The distance of the radiation entrance surface 10 the lens 5 is thus at a distance to the surface of the LED 4 arranged, which is more than a third of the diameter of the radiation entrance surface 10 the lens 5 , in the present example even approximately equal to half. Too long distance from lens 5 and LED 4 would require a very large lens diameter to equalize the amount of emitted light with the lens 5 to capture as with a closer to the LED 4 located lens 5 , However, this increases the manufacturing effort and the LED module 1 gets very tall and unwieldy. It has proved to be advantageous, the distance from the radiation entrance surface 10 the lens 5 and LED 4 smaller than the lens diameter to choose.

Due to the aspherical shape of the lens 5 a very homogeneous radiation characteristic is achieved. In addition, the border area 11 the lens 5 inclined relative to the optical axis A at an angle of about 22 °, which aberrations in the edge region of the lens 5 reduces or prevents by as few of the rays as possible the lens 5 in this unfavorable area for the imaging properties.

To the side of the lens 5 To exploit emerging light beams for the illumination of the area to be illuminated, are the LEDs 4 perpendicular to the main emission direction, which in the exemplary embodiment is identical to the optical axis A, on all sides by the reflector 6 surround. The reflector 6 is made up of several rings 6a . 6b . 6c together having a plurality of facets not recognizable in this representation, for example between 10 and 25. The reflector extends in the main emission direction 6 over the lens 5 in order to direct as much of the radiation as possible into the area to be illuminated. In particular, the middle and outer angular ranges of the radiation characteristic are covered. The faceting allows for mixing of different areas of the group 3 from LED 4 radiated light, so that a homogeneous radiation behavior with uniform distribution of color as well as the color temperature can be achieved, even if both within the LEDs 4 as well as between the individual LEDs 4 Differences exist.

The reflector 6 is made of an aluminum alloy, which makes it for heat dissipation from the light emitting diodes 4 can be used. On the inside it is provided with a suitable reflective coating.

The reflector 6 is by means of suitable fasteners according to the prior art on the support element 2 fixed. It is also conceivable, for example, that the fastening elements 7 the lens 5 to be used. Furthermore, other embodiments of the reflector are 6 conceivable, for example, by making this one ring only 6a exists or is cylindrical without facets. The height can be different than in the embodiment, in particular lower, are selected. For example, it is conceivable that the reflector 6 only up to the top of the lens 5 or even only up to the radiation entrance surface 10 enough.

The fasteners 7 the lens 5 may additionally or alternatively also on the reflector 6 be fixed, for example, by placing these laterally from the lens 5 to the reflector 6 pass. This allows the unit of lens 5 and reflector 6 be assembled as a joint in the manufacture, which facilitates the production. Depending on the circumstances, it is also conceivable that lens 5 and reflector 6 be made in one piece from a transparent polymer material and the reflector 6 then provided on its inside with a reflective coating.

The shaping of lens 5 and reflector 6 depends essentially on the shape of the LED 4 or the group 3 from LED 4 and the desired radiation characteristics. Thus, in the exemplary embodiment shown, an approximately circular emission characteristic is achieved from a rectangular light source. Likewise, the distance between the edge 11 the lens 5 and the reflector 6 depending on the application selectable to the distribution between the proportion of through the lens 5 going to set and the light passed by it. Under certain circumstances, this distance may also be important for the cooling of the LED and, depending on the application, should therefore not be less than a minimum.

Depending on the desired characteristic, instead of the plano-convex lens 5 of course, another lens 5 or even a combination of lenses are used. In particular Konkavkonvexlinsen are suitable if a relatively wide beam angle of about 30 ° to 60 ° to be achieved.

Claims (23)

LED module ( 1 ) comprising at least one carrier element ( 2 ), at least one on the support element ( 2 ) arranged light emitting diode (LED) ( 4 ) and at least one lens arranged in the beam path of the radiation emanating from the LED ( 5 ), characterized in that the LED module has at least one reflector ( 6 ) and one of the LEDs ( 4 ) facing radiation entrance surface ( 10 ) of the lens ( 5 ) from the surface of the LED ( 4 ) is arranged at a distance. LED module ( 1 ) according to claim 1, characterized in that at least two LEDs ( 4 ) in a preferably rectangular group ( 3 ) of LED ( 4 ) are summarized. LED module ( 1 ) according to claim 1 or 2, characterized in that the LED ( 4 ) facing radiation entrance surface ( 10 ) of the lens ( 5 ) at a distance of at least 2.5 mm, preferably of at least 5 mm, to the surface of the LED ( 4 ) is arranged. LED module ( 1 ) according to one of claims 1 to 3, characterized in that the LED ( 4 ) facing radiation entrance surface ( 10 ) of the lens ( 5 ) at a distance to the surface of the LED ( 4 ) of at least the maximum linear dimension, preferably at least 2 times the maximum linear dimension of the LED ( 4 ) and / or the group ( 3 ) of LED ( 4 ) corresponds. LED module ( 1 ) according to one of claims 1 to 4, characterized in that the LED ( 4 ) facing radiation entrance surface ( 10 ) of the lens ( 5 ) at a distance to the surface of the LED ( 4 ) is arranged, which is at least a quarter of the diameter of the radiation entrance surface ( 10 ) of the Lens ( 5 ), in particular at least one third of the diameter of the radiation entrance surface ( 10 ) of the lens ( 5 ) corresponds. LED module ( 1 ) according to one of claims 1 to 5, characterized in that the LED ( 4 ) facing radiation entrance surface ( 10 ) of the lens ( 5 ) at a distance of at most 30 mm, preferably at most 20 mm from the surface of the LED ( 4 ) is arranged. LED module ( 1 ) according to one of claims 1 to 6, characterized in that the LED ( 4 ) facing radiation entrance surface ( 10 ) of the lens ( 5 ) at a distance to the surface of the LED ( 4 ) which is at most 8 times the maximum linear dimension, preferably at most 5 times the maximum linear dimension of the LED ( 4 ) and / or the group ( 3 ) of LED ( 4 ) corresponds. LED module ( 1 ) according to one of claims 1 to 7, characterized in that the LED ( 4 ) facing radiation entrance surface ( 10 ) of the lens ( 5 ) at a distance to the surface of the LED ( 4 ) which is at most 1.5 times the diameter of the radiation entrance surface ( 10 ) of the lens ( 5 ), in particular special at most the diameter of the radiation entrance surface ( 10 ) of the lens ( 5 ) corresponds. LED module ( 1 ) according to one of claims 1 to 8, characterized in that the lens ( 5 ) is formed essentially of a polymer material. LED module ( 1 ) according to one of claims 1 to 9, characterized in that the reflector ( 6 ) the LED ( 4 ) is surrounded on all sides perpendicular to the main emission direction. LED module ( 1 ) according to one of claims 1 to 10, characterized in that the reflector ( 6 ) the arrangement of LED ( 4 ) and lens ( 5 ) is surrounded on all sides perpendicular to the main emission direction LED module ( 1 ) according to one of claims 1 to 11, characterized in that the lens ( 5 ) as plano-convex lens ( 5 ) is trained. LED module ( 1 ) according to one of claims 1 to 11, characterized in that the lens ( 5 ) is designed as Konkavkonvexlinse. LED module ( 1 ) according to one of claims 1 to 13, characterized in that at least one surface of the lens ( 5 ) is formed aspherical. LED module ( 1 ) according to one of claims 1 to 14, characterized in that the edge of the lens ( 5 ) with the optical axis A an angle between 10 ° and 60 °, preferably between 20 ° and 50 °. LED module ( 1 ) according to one of claims 1 to 15, characterized in that the LED module ( 1 ) several LEDs ( 4 ). LED module ( 1 ) according to one of claims 1 to 16, characterized in that at least one fastening element ( 7 ) for fixing the lens ( 5 ) on the carrier element ( 2 ) is provided. LED module ( 1 ) according to one of claims 1 to 17, characterized in that at least one fastening element ( 7 ) for fixing the lens ( 5 ) on the reflector ( 6 ) is provided. LED module ( 1 ) according to one of claims 1 to 18, characterized in that at least one fastening element ( 7 ) and the lens ( 5 ) are integrally formed. LED module ( 1 ) according to one of claims 1 to 19, characterized in that the fastening element ( 7 ) at least one snap connection for connection to the reflector ( 6 ) and / or the carrier element ( 2 ) having. LED module ( 1 ) according to one of claims 1 to 20, characterized in that the reflector ( 6 ) at least two annular segments ( 6a . 6b . 6c ). LED module ( 1 ) according to one of claims 1 to 21, characterized in that at least one segment ( 6a . 6b . 6c ) of the reflector ( 6 ) has at least 6, preferably between 10 and 14, in particular 12 facets. LED module ( 1 ) according to one of claims 1 to 22, characterized in that the reflector ( 6 ) is formed essentially of a thermally highly conductive material, in particular aluminum.