WO2000070687A1

WO2000070687A1 - Led module for signaling devices

Info

Publication number: WO2000070687A1
Application number: PCT/DE2000/001537
Authority: WO
Inventors: Günter Waitl; Simon BLÜMEL
Original assignee: Osram Opto Semiconductors Gmbh & Co. Ohg
Priority date: 1999-05-14
Filing date: 2000-05-15
Publication date: 2000-11-23
Also published as: EP1179219B1; DE19922361A1; DE19922361C2; CN1193437C; CN1350704A; EP1179219A1

Abstract

The invention relates to an LED module having a regular array of LEDs (10), wherein each LED (10) is provided with a lens (20) and the LEDs (10) are mounted on a plate (1). An optics support plate (2) is provided that contains a regular arrangement of light bundling optical devices (20; 30) corresponding to the LED array. The light bundling optical devices can be lenses (20) or optical channels with reflecting side walls which are integrated into the optics support plate (2).

Description

description

LED module for signaling devices

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

Conventional railway signaling technology usually uses a strong light source with small dimensions such as the filament of an incandescent lamp, placed in the focus of an optical lens and projected into infinity at the level of the driver. Due to the high luminance of the light source, there is a very high light intensity with a very small beam angle, so that the signal can still be clearly recognized even from a great distance (> 3 km).

As is known, however, incandescent lamps have a limited lifespan, the failure of the incandescent lamp used for a railway signal device always being associated with a total failure of the entire signal device. As a precaution, the light bulbs in the railway signaling devices must be replaced at regular intervals. These time intervals are much shorter than the average life of the lamp, so that the replacements involve a considerable amount of material and time.

For safety reasons, incandescent lamps which have a second incandescent filament are used in the railway signaling devices. This second filament is switched on if the first filament fails. However, because the second filament is not optimally arranged in the focus of the lens, the light intensity of the path signal drops to approx. 12% in the event of an error. Therefore, a repair must be carried out immediately in this case.

Also with other signaling devices such as guidance signaling devices that are embedded in the ground for the illuminated marking of paths, roads or runways there are similar problems due to the use of conventional incandescent lamps as light sources.

Due to the high sensitivity to failure of conventional incandescent lamps, it is therefore advisable to use semiconductor light-emitting diodes (LEDs) as light sources, since LEDs not only have a significantly longer service life, but also a better efficiency when converting electrical energy into radiation energy in the visible spectral range and associated with - have a lower heat emission and an overall smaller space requirement. However, in order to provide an LED arrangement which is suitable for a web signal device or a comparable device such as a headlight, as with the conventional web signal device, optics are required which are suitable for bundling the light emitted by the individual LEDs in such a way that it also is perceived at a relatively large distance as an extensive and brightly shining light source. A system consisting of an LED arrangement with only one lens is not suitable since the beam angle cannot be reduced below a physically determined limit value.

An LED module is known from US-A-5404282, in which a number of LEDs are fixedly mounted between two parallel, electrically conductive rods. According to FIG. 3 of 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 produced by providing the light exit surface of this synthetic resin block with a bump, ie a section that is curved outwards. However, each unit consisting of an LED and a lens must be manufactured individually in this way. This type of production is too complex for the production of a matrix from several LEDs with associated lenses. In addition, with the arrangement described, the failure of the LED means that the lens can no longer be used, making this arrangement very inflexible. It is therefore the object of the present invention to provide an LED module, in particular for use in signaling devices or lighting devices, which can be manufactured and constructed as simply as possible and can be used as flexibly as possible.

This object is achieved by the features of patent claim 1. Accordingly, the invention describes an LED module with a regular arrangement of LEDs, which are mounted on a circuit board and are each provided with a light-bundling optical device, wherein an optical support plate is also provided, which the light-bundling optical devices in one of the LED Arrangement corresponding regular arrangement contains. Advantageous further developments and embodiments are the subject of claims 2 to 18.

In a first embodiment, the light-bundling optical devices are formed by lenses. In a variant thereof, the optics carrier plate contains an arrangement of depressions corresponding to the LED arrangement, into which the lenses can be inserted as individually manufactured components. Preferably, the lenses are each constructed in such a way that they have a square-shaped main body with an outwardly curved light exit surface and a base which is tapered in cross-section with respect to the main body and corresponds to the recess of the optics carrier plate. However, it can also be provided that elevations are arranged in the optics carrier plate instead of the depressions, onto which the lenses can be attached.

A particular advantage of this embodiment is that the module can be easily and quickly adapted to different areas of application and the parameters specified thereby.

According to a further variant of the first embodiment, the lenses are integrally formed in the optics carrier plate. In In this case, the optical carrier plate must consist of a material that is transparent to the emission wavelength of the LEDs.

In a second embodiment, the light-bundling optical devices are formed by optical channels which are integrated in the optics carrier plate and which have inclined or curved, reflecting inner walls.

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

Further embodiments can be formed by combinations of the first and the second embodiment.

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

An LED which is preferably used for the LED module according to the invention is, for example, in the article "SIEMENS SMT-TOPLED for surface mounting" by F. Möllmer and G. Waitl in the magazine Siemens Components 29 (1991), issue 4, p. 147 in connection described with picture 1. This form of LED is extremely compact and allows a large number of LEDs to be arranged on the circuit board.

The LED module according to the invention is particularly suitable for installation in signaling devices such as railway signaling devices or control signal devices or embedded in the floor lighting equipment of any kind used for other purposes.

The invention is explained in more detail below on the basis of exemplary embodiments of the two embodiments in conjunction with the drawings. Show it:

Fig.l is a side or cross-sectional view of a first embodiment of an LED module according to the invention;

2A shows a side view of a lens used in an LED module according to FIG. 1; and FIG. 2B shows a view of the lens from the side of the light exit surface;

3 shows a side or cross-sectional view of a second embodiment of an LED module according to the invention.

A first embodiment of an LED module according to the invention with a circuit board 1 and an optics carrier plate 2 is shown in a side view in FIG. A plurality of LEDs 10 are shown on the circuit board 1 in the arrangement of a matrix. The arrangement can also be formed by a single row of LEDs. A metal core board is preferably used as the board 1 in order to improve the heat dissipation from the LEDs, as a result of which the luminous efficacy of the LEDs can be improved. The LEDs are preferably mounted on the circuit board 1 using surface mounting technology SMT (Surface-Mount Technology). The already mentioned SIEMENS SMT-TOPLED can be used as LED 10. The circuitry structure of the LEDs 10 can be such that several separate, independent circuits are arranged. This ensures a high level of reliability for the module. For example, the LEDs 10 can be arranged in two independent circuits, each with 15 parallel strands, two LEDs 10 being connected in series in each individual strand.

At a small distance from the top of the LEDs 10, the optics carrier plate 2 containing the lens arrangement is orderly . The circuit board 1 and the optics carrier plate 2 can be rigidly connected to one another in a suitable manner so that their relative position to one another remains constant. The circuit board 1 and the optics carrier plate 2 are preferably connected to one another via a snap-in plug connection.

The optics carrier plate 20 contains a plurality of lenses 20, which are individually assigned to the LEDs 10. An optics carrier plate 20 can be used, in whose surface on the light exit side the lenses 20 are shaped, for example, as elevations, so that the lenses 20 are integrally connected to the optics carrier plate 2. However, an arrangement as in FIG. 1 is preferred, in which the lenses 20 are manufactured as individual components and can be inserted into the optics carrier plate 2 by means of a snap-in plug connection. For this purpose, the optics carrier plate 2 is shaped in the manner of a type case with a number of depressions 25 which are 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 is a further light-bundling optical device 11, in particular a lens, which is thus connected upstream of the respective light-bundling optical device 20, 30 of the optics carrier plate 2 in the direction of radiation of the LED component 10.

2A, B, a single lens 20 is shown in a side view (A) and a view from the side of the light exit surface (B). The lens 20 accordingly consists of a square-shaped main body 21 and a base 22 connected to it on the side opposite the 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 optics support plate 2, so that in the inserted

State of the lens 20, the surface of the main body 21 projecting at the boundary of the base 22 to the main body 21 rests on the optics carrier plate 2. Furthermore, the cross section of the main body 21 is dimensioned such that the main bodies 21 of the lenses 20 are in contact with one another without gaps in the inserted state. lying there. The exemplary embodiment according to the invention thus has the advantage that the module appears as a homogeneously illuminated surface when viewed from a distance of a few meters.

Depending on the manufacturing outlay, the complementarity of the optical support plate 2 and the lenses 20 can also be carried out in reverse, in which case instead of the recesses 25 corresponding elevations are formed in the optical support plate 2 and the individual lenses 20 are provided with corresponding complementary recesses.

Simple structural measures can be taken to ensure that the plug connection snaps into place. 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 such 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 can be shaped as reflectors to increase the luminous efficiency.

Polymethyl methacrylate (PMMA) with a refractive index of 1.5 is particularly suitable as the material for the optics carrier plate 2 and the lenses 20. But others can too

Plastics are used, the shape of the lens, i.e. the shape of the curved surface 21a must be changed. An injection moldable material is preferably used for series production with large quantities.

A second embodiment of an LED module according to the invention is shown in a side view in FIG. As in FIG. 1, a circuit board 1 with a regular arrangement of LEDs 10 applied thereon is used. The Here, however, the optics carrier plate 2, as light-bundling optical devices, has a regular arrangement of optical channels 30 corresponding to the LED arrangement, which channels are formed in the optics carrier plate 2 and have reflecting side walls. As shown, the side walls are inclined in such a way that the channel cross section increases in the direction of light propagation. Instead of straight sidewalls, a curved course can also be provided. The channels 30 are preferably formed as bores through the optics carrier plate 2, which are either continuous or extend at least over part of the cross section of the optics carrier plate 2. However, it can also be provided that the channels 30 consist of a material with a relatively high refractive index, as in the case of a refractive index-guided glass fiber, while the material of the optics carrier plate 2 surrounding the channels 30 has a relatively low refractive index, so that this is due to the Interface light is reflected there by total reflection. The change in the refractive index can be gradual or gradual.

Further embodiments can also be formed, which are composed of the two described embodiments. For example, additional lenses can be provided in the LED module of the second exemplary embodiment (FIG. 3). These can be placed on the channels 30 on one side of the optics carrier plate 2. If the channels 30 are formed by bores, the additional lenses can also be inserted into these bores as in the first exemplary embodiment.

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

The module according to the invention can be used particularly advantageously in the case of railway signaling devices. However, it can also be used for other signaling devices, such as guidance signal devices embedded in the ground, which are used to illuminate paths, streets, squares, tunnels, take-off and landing trains or the like. The flat design of the LED module according to the invention has a particularly advantageous effect in such applications.

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

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

Claims

claims

1. LED module, with a regular arrangement of individual, in particular surface-mountable LED components (10) which are mounted on a main surface of an electrical connection plate (1), in particular a circuit board, each LED component (10) at least one in the radiation direction arranged light-bundling optical device (20; 30) is assigned, characterized in that an optical support plate (2) is provided which contains the optical devices (20; 30) arranged in accordance with the regular arrangement of the LED components (10) and the optics carrier plate (2) is positioned at a distance from the electrical connection plate (1) above the LED components (10).

2. LED module according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the light-bundling optical devices (20; 30) are lenses (20).

3. LED module according to claim 2, characterized in that the optics support plate (2) is arranged in relation to the electrical connection plate (1) that each LED chip of the LED components (10) at the focal point of this- associated lens (20) is positioned.

4. LED module according to claim 2 or 3, characterized in that the optics carrier plate (2) contains an arrangement of depressions (25) or elevations corresponding to the LED arrangement, and the lenses (20) can be inserted as individually manufactured components in the recesses (25) or can be attached to the elevations.

5. LED module according to claim 2, characterized in that the lenses (20) are each constructed such that they have a square-shaped main body (21) with an outwardly curved light exit surface, and - one in cross-section with respect to the main body (21) and tapered have a base (22) complementary to the recess (25) of the optical support plate (2).

6. LED module according to claim 5, so that the square-shaped main body (21) lie against one another without gaps in the inserted state of the lenses (20).

7. LED module according to claim 5 or 6, so that the side walls of the depressions (25) and / or the main body (21) and / or the base (22) are formed as reflectors.

8. LED module according to claim 2, so that the lenses (20) are integrally formed in the optics support plate (2).

9. LED module according to claim 1, so that the light-bundling optical devices (20) in the optics carrier plate (2) are shaped optical channels (30) with reflecting walls.

10. LED module according to claim 9, characterized in that the channels (30) are bores or regions with a relatively high refractive index formed in the optical support plate (2).

11. LED module according to one of the preceding claims, that the optics carrier plate (2) and / or the lenses (20) contain polymethyl methacrylate (PMMA).

12. LED module according to one of the preceding claims, that the optics carrier plate (2) and / or the lenses (20) are injection molded.

13. LED module according to one of the preceding claims, characterized in that - directly on each LED component (10) a further light-bundling optical device (11), in particular a lens is arranged, which thus in the direction of radiation of the respective LED component (10) upstream of the respectively assigned light-bundling optical device (20; 30) of the optics carrier plate (2).

14. LED module according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the board (1) is a metal core board.

15. LED module according to one of the preceding claims, d a d u r c h g e k e n n e e c h n e t that - the LEDs (10) are connected to at least two independent circuits.

16. LED module according to one of the preceding claims, characterized in that - the LEDs (10) have a conversion material through which at least part of the LEDs (10) emitted Light radiation is converted into wavelengths, so that the optical impression of white light LEDs is created.

17. Use of an LED module according to one or more of claims 1 to 16 for signaling devices, in particular for railway signaling devices or guidance signal devices embedded in the ground for illuminated marking of paths, roads, tunnels, runways and the like.

18. Lighting device containing an LED module according to one of claims 1 to 16.