EP1179219B1 - Led module for signaling devices - Google Patents

Description

The invention relates to an LED module, which can be used in particular in signaling devices with a very small beam angle.

Conventionally, in the conventional orbit signaling technique, a strong light source of small dimensions, e.g. the filament of an incandescent lamp, placed in the focal point of an optical lens and projected at infinity at eye level of the train driver. Due to the high luminance of the light source produces a very high light intensity at a very small beam angle, so that the signal from a long distance (> 3 km) is still clearly visible.

However, as is known, incandescent lamps have a limited service life, with the failure of the incandescent lamp used for a railway signaling device always being associated with total failure of the entire signaling device. Therefore, the incandescent lamps must be replaced at the railway signal devices as a precaution at regular intervals. These time intervals are far shorter than the average life of the lamp, so that with the replacement of a considerable material and time is required.

For safety reasons incandescent lamps are used in the railway signal devices, which have a second filament. This second filament is switched on failure of the first filament. However, since the second filament is not arranged optimally in the focus of the lens, the light intensity of the path signal decreases in the event of a fault to approximately 12%. Therefore, a repair must be done immediately in this case.

Also in other signaling devices such as Leitsignaleinrichtungen that are embedded in the ground for luminescent marking of roads, roads or runways exist Similar problems due to the use of conventional light bulbs as light sources.

Due to the high failure sensitivity of conventional incandescent lamps, it is therefore appropriate to use as light sources semiconductor light emitting diodes (LEDs), since LEDs not only a significantly longer life, but also a better efficiency in the conversion of electrical energy in radiation energy in the visible spectral range and - associated - Have a lower heat output and a lower overall space requirement. However, in order to provide a suitable for a railway signal device or a comparable device such as a headlamp LED array, it is necessary as well as the conventional railway signal device of optics, which is adapted to focus the light emitted by the individual LEDs so that it also in relative long distance is perceived as an extended and bright light source. A system of an LED arrangement with only one lens is not suitable, since in this case the radiation angle can not be reduced below a physical limit.

From the US-A-5404282 An LED module is known in which a number of LEDs between two parallel electrically conductive rods is firmly mounted. According to the Figure 3 In this document, the LEDs used therein are each cast with their electrical leads in a transparent plastic such as epoxy resin. A lens can be made by providing the light exit surface of this resulting resin block with a bump, ie, a convex portion. However, each unit consisting of an LED and a lens must be manufactured one by one in this way. For the production of a matrix of several LEDs with associated lenses, this production is too expensive. In addition, in the described arrangement, the failure of the LED means that the lens can not be used, whereby this arrangement is very inflexible.

Out EP 0 303 741 Furthermore, an LED display is known, which has a plurality of LED chips, which are mounted on a common substrate. In one embodiment of the LED display, each LED chip is followed by a lens, which is inserted into a corresponding bore in a carrier plate. The assembly of the individual LED chips on a substrate, however, is relatively expensive and requires in particular for each chip, the formation of a wire connection from the chip top to the substrate.

In DE 196 23 881 A1 For example, an electroluminescent display is described which comprises a display panel with a plurality of differently colored pixels and a lens system covering the display panel. The lens system consists of close-fitting individual lenses, which lead to an improvement in the directional characteristic of the emitted luminous flux.

IN WO 97/50132 Light emitting semiconductor devices are disclosed which contain a semiconductor body and a luminescence conversion element. The luminescence conversion element converts a part of the radiation emitted by the semiconductor body in the blue, green or ultraviolet spectral range into light of a different wavelength, so that the optical impression of mixed-color, in particular white light arises.

Other optical or optoelectronic devices are in the publications GB 2 329 011 A . EP 0 633 163 A1 . EP 0 400 176 A1 and EP 0 762 515 A2 described.

It is therefore an object of the present invention to provide an LED module, in particular for use in signaling devices or lighting devices, which can be as simple as possible and constructed and used as flexible as possible.

This object is solved by the features of patent claim 1. Advantageous developments and embodiments are the subject of claims 2 to 12.

The light-bundling optical devices are formed by lenses. The optics support plate includes an array of wells corresponding to the LED array, which are bores into which the lenses are plugged as individually manufactured components. The lenses are each constructed such that they have a square-shaped main body with an outwardly curved light exit surface and a tapered in cross-section relative to the main body and corresponding to the recess of the optical support plate complementary pedestal.

A particular advantage of this embodiment is that the module can be adapted in a simple and fast way different application areas and the parameters given thereby.

It is also possible that the light-bundling optical devices are formed by optical channels, which are integrated into the optical carrier plate and having the inclined or curved, reflective inner walls.

In a preferred development, a lens is arranged directly on each LED component, which is thus connected upstream of the respective light-bundling optical device of the optical carrier plate. As a result, very narrow radiation angles can advantageously be achieved.

Other embodiments may be formed by combinations of the first and second embodiments.

It is furthermore preferred that the optical carrier plate and / or the lenses contain polymethyl methacrylate (PMMA). Regardless of the choice of the material of the optical carrier plate and the lenses, it is also desirable if the optical carrier plate and / or the lenses - optionally as an integral part - are made by injection molding.

An LED preferably used for the LED module according to the invention is described, for example, in the article " SIEMENS SMT-TOPLED for surface mounting "by F. Möllmer and G. Waitl in the journal Siemens Components 29 (1991), No. 4, p. 147 described in connection with Figure 1. This shape of the LED is extremely compact and allows the arrangement of a variety of LEDs on the board.

The LED module according to the invention is particularly suitable for installation in signaling devices such as railway signaling devices or embedded in the ground Leitsignaleinrichtungen or Lighting devices of any kind used for other purposes.

• Fig.1 eine Seiten- oder Querschnittsansicht auf eine Ausführungsform gemäß eines ersten Aspekts eines erfindungsgemäßen LED-Moduls;
• Fig.2A eine Seitenansicht einer bei einem LED-Modul nach Fig.1 eingesetzten Linse; und Fig.2B eine Ansicht der Linse von der Seite der Lichtaustrittsfläche;
• Fig.3 eine Seiten- oder Querschnittsansicht auf eine Ausführungsform gemäß eines zweiten Aspekts eines erfindungsgemäßen LED-Moduls.

In the following the invention will be explained in more detail with reference to embodiments of the two embodiments in conjunction with the drawings. Show it:

• Fig.1 a side or cross-sectional view of an embodiment according to a first aspect of an LED module according to the invention;
• 2A a side view of a LED module after Fig.1 inserted lens; and 2B a view of the lens from the side of the light exit surface;
• Figure 3 a side or cross-sectional view of an embodiment according to a second aspect of an LED module according to the invention.

A first aspect of an embodiment of an LED module according to the invention with a circuit board 1 and an optical carrier plate 2 is shown in FIG Fig.1 shown in a side view. On the circuit board 1, a plurality of LEDs 10 are shown in the arrangement of a matrix. The arrangement can also be formed by a single row of LEDs. As the board 1, a metal core board is preferably used to improve the heat dissipation of the LEDs, whereby the light output of the LEDs can be improved. The LEDs are preferably mounted in the surface mounting technology SMT (Surface Mount Technology) on the board 1. As LED 10, the already mentioned SIEMENS SMT-TOPLED can be used. The circuit design of the LEDs 10 can be made so that several separate, independent circuits are arranged. As a result, a high reliability of the module can be ensured. For example, the LEDs 10 may be in two independent circuits each having 15 parallel ones Strands are arranged, with two LEDs 10 are connected in series in each strand.

At a small distance from the top of the LEDs 10, the optical carrier plate 2 containing the lens assembly is arranged. The circuit board 1 and the optical support plate 2 may be rigidly connected together in a suitable manner, so that their relative position to each other remains constant. Preferably, the circuit board 1 and the optical support plate 2 are connected to each other via a snap-in connector.

The optical carrier plate 20 includes a plurality of lenses 20 individually associated with the LEDs 10, respectively. As in Fig.1 shown, the lenses 20 are made as individual components and inserted into the optical support plate 2 by a snap-in connector. For this purpose, the optical carrier plate 2 is shaped in the manner of a setting box with a number of recesses 25, which are present in the same matrix-like arrangement as the LEDs 10. These depressions 25 have, for example, a circular cross-section.

Immediately on each LED component 10, a further light-bundling optical device 11, in particular a lens is arranged, which is thus upstream of the respective light-bundling optical device 20,30 of the optical carrier plate 2 in the emission direction of the LED device 10.

In 2A, B For example, a single lens 20 is shown in a side view (A) and a view from the side of the light exit surface (B). Accordingly, the lens 20 consists of a square-shaped main body 21 and a base 22 connected thereto on the opposite side of the light exit surface, which is tapered in cross-section with respect to the main body 21. The base 22 is complementary to the recess 25 of the optical support plate 2, so that in the inserted state of the lens 20, the protruding at the boundary of the base 22 to the main body 21 surface of the main body 21 rests on the optical support plate 2. Further, the cross section of the main body 21 is dimensioned such that when inserted State, the main body 21 of the lenses 20 abut each other gapless. The embodiment of the invention thus has the advantage that the module appears when viewed from a distance of a few meters as homogeneously illuminated surface.

By simple structural measures can be achieved that a locking of the connector is achieved. This is known to the person skilled in the art and will not be discussed further here.

The main body 21 has on the light exit surface an outwardly curved surface 21a, through which the actual lens is formed. Depending on the lens material and its refractive index, the curved surface 21a can be shaped in such a way that the active surface of the LED 10 lies in the focal point of the lens 20.

The side walls of the main body 21 and / or the base 22 may be formed as reflectors to increase the light output.

As a material for the optical carrier plate 2 and the lenses 20 is particularly well polymethyl methacrylate (PMMA) with a refractive index of 1.5. However, it is also possible to use other plastics, in which case the shape of the lens, possibly due to a different refractive index, may be used. the shape of the curved surface 21a must be changed. For series production with large numbers, an injection-moldable material is preferably used.

A second aspect of an embodiment of an LED module according to the invention is shown in FIG Figure 3 shown in a side view. This one will be like in Fig.1 a board 1 with a regular array of LEDs 10 applied thereto. The

However, optical carrier plate 2 here has, as light-bundling optical devices, a regular arrangement of optical channels 30 corresponding to the LED arrangement, which are formed in the optical carrier plate 2 and have reflective side walls. The side walls are, as shown, inclined in such a way that the channel cross-section increases in the direction of light propagation. Instead of straight side walls can also be provided a curved course. The channels 30 are formed as bores through the optical carrier plate 2, which are either continuous or extend at least over part of the cross section of the optical carrier plate 2. But it may also be provided that the channels 30 are made of a material having a relatively high refractive index, as in a refractive index guided glass fiber, while the channels 30 immediate material of the optical support plate 2 has a relatively low refractive index, so that the impacting on the interface Light is reflected at this by total reflection. The change in the refractive index may be stepped or gradual.

Other embodiments may also be formed, which are composed of both described aspects of the embodiments. For example, in the LED module of the second embodiment ( Figure 3 ) additional lenses are provided. These can be plugged into these holes on one side of the optical carrier plate 2 in the channels 30, which are formed by holes.

The LED module according to the invention has the advantage that it appears when viewed from a distance of a few meters as homogeneously illuminated surface.

The module according to the invention can be advantageously used particularly in railway signaling devices. But it can also be used for other signaling devices such as embedded in the ground Leitsignaleinrichtungen, the luminescent marking of roads, streets, squares, tunnels, take-off and landing serve tracks or the like. In such applications, the flat design of the LED module according to the invention has a particularly advantageous effect.

Another field of application are traffic lights or spotlights, such as spotlights, or other such lighting objects, as they can be used for effect lighting in discotheques for example.

The emission wavelength of the LED is in principle arbitrary. Alternatively, multicolor signals can be generated by using LEDs of different colors. In order to mimic a conventional railway signal device as far as possible in the optical properties, a white light LED can also be used. For this purpose, for example, an LED of the shortest possible wavelength, such as GaN in the blue spectral range, used, then to which a suitable converter material for producing shorter wavelengths is applied, so that the optical impression of a white light source results from the wavelength mixing.

Claims (12)

1. LED module comprising

   - a regular arrangement of individual, in particular surface-mountable LEDs (10) which are mounted on a main surface of an electrical terminal board (1), in particular a printed circuit board, each LED (10) being assigned a light-concentrating first and second optical device (20; 30) arranged in a direction of emission, and

   - an optics support plate (2), wherein

   - the optics support plate (2) is positioned at a distance from the electrical terminal board (1) above the LEDs (10),

   - the first light-concentrating optical device is a bore (30) formed in the optics support plate (2) and having reflecting walls, and

   - the second light-concentrating optical device is a lens (20),

   characterized in that

   - the lens (20) comprises
   a square main body with an outwardly curved light exit surface and a socket which is tapered in cross section in relation to the main body and complementary to the bore (30) in the optics support plate, wherein the socket is plugged into the bore.
2. LED module according to Claim 1, wherein

   - the optics support plate (2) is arranged with reference to the electrical terminal board (1) in such a way that each LED chip of the LED components (10) is positioned at the focal point of the lens (20) associated therewith.
3. LED module according to Claim 1, wherein

   - the square main bodies (21) join one another without gaps in the plug-in state of the lenses (20).
4. LED module according to Claim 1, wherein

   - the side walls of the main body (21) and/or of the socket (22) are formed as reflectors.
5. LED module according to one of the preceding claims,

   - the optics support plate (2) and/or the lenses (20) contain polymethylmethacrylate (PMMA).
6. LED module according to one of the preceding claims, wherein

   - the optics support plate (2) and/or the lenses (20) are produced using injection moulding.
7. LED module according to one of the preceding claims, wherein

   - arranged directly on each LED (10) is a further lens (11), which is thereby arranged in the direction of emission of the respective LED (10) upstream of the respectively assigned light-concentrating optical device (20; 30) of the optics support plate (2).
8. LED module according to one of the preceding claims, wherein

   - the printed circuit board (1) is a metal-core printed circuit board.
9. LED module according to one of the preceding claims, wherein

   - the LEDs (10) are connected to at least two independent circuits.
10. LED module according to one of the preceding claims, wherein

    - the LEDs (10) comprise a conversion material which can convert the wavelength of at least a portion of the optical radiation emitted by the LEDs (10) such that the optical impression of white LEDs is produced.
11. Use of an LED module according to one or more of the preceding claims for signalling devices, in particular for railway signalling devices or guiding signalling devices recessed into the ground for the purpose of luminous marking of paths, roads, tunnels, runways and the like.
12. Illuminating device including an LED module according to one of Claims 1 to 10.

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