EP2491299A1

EP2491299A1 - Led module and lamp containing an led module

Info

Publication number: EP2491299A1
Application number: EP10782425A
Authority: EP
Inventors: Quinten Van De Vrie
Original assignee: Leds Progress Holding BV
Current assignee: Leds Progress Holding BV
Priority date: 2009-10-25
Filing date: 2010-10-24
Publication date: 2012-08-29
Also published as: NL1037416C2; NL1038327A; NL1038327C2; WO2011049435A1

Abstract

An LED module contains a number of LEDs (9) and a reflector (2) to reflect the light emitted by the LEDs. The LED module contains a ring of LEDs with a reflector cup 13 having been installed for every LED and with a second communal ring-shaped reflector compartment 14 having been installed for the collective reflector cups. The ring-shaped reflector compartment 14 contains a raised edge (15a) enclosing a central compartment (16) which is screened off from the light of the LEDs. An optical sensor (12) is preferably installed in the central compartment.

Description

Led Module and lamp containing an LED module.

Field of the invention. The invention concerns an LED module containing a number of LEDs and a reflector to reflect the light emitted by the LEDs.

Background of the invention. An LED module as described in the first paragraph is known from the German patent application DE 10 2004011600. The reflector is shaped as a continuous ring with an internal and external reflector surface, the surfaces of which are paraboloid shaped. A ring fitted with LEDs has been placed in the reflector. LED is the standard term for a Light Emitting Diode. The LEDs emit light sideways, in the direction of the reflecting surfaces of the reflector. The light is reflected by the reflecting surfaces of the reflector. The ring-shaped reflector can have an opening in the centre behind which an LED can also be placed. Such a module can be used, for example, as the tail/rear lights of a vehicle. The rear of the ring can be given a different function, e.g. it may be provided with reflectors. The light image consists of a central, bright part, and an outer ring of light separated by a dark band. Although this could be suitable for the tail/rear lights of a car, it is not suitable for existing LED lamps in light fixtures.

The known lamp is not suitable for the ever-evolving miniaturisation of LED modules.

The ever-evolving miniaturisation of LED modules has, among other things, given rise to the aim to create space for electronic circuits in the LED module.

An obstacle in this respect is the fact that, in order to achieve rapid usability of LED lamps, it is important that the LED module is not larger than existing LED lamps as otherwise the module will no longer fit in existing light fixtures. Therefore the outer dimensions of the module are preferably not or hardly changed. This sets restrictions on the design since on the one hand the intention is to win space, whereas on the other hand the outer dimensions are limited and the total light output and the light image must of course not be negatively affected. And, in addition, thermal management is important. Summary of the invention

To comply with these requirements, which may initially seem mutually contradictory, the invention provides an LED module which contains a ring of LEDs, with the module containing a reflector cup for every LED and with a communal ring-shaped reflector compartment positioned in front of the set of reflector cups, and with the ring-shaped reflector compartment containing a raised edge enclosing a central compartment, screened off from the light of the LEDs.

This configuration enables a targeted, more or less even bundle of light rays to be obtained where the LEDs and the reflectors need less space. A compartment has been left open in the centre of the LED module and some of the electronics which are normally contained in the power supply unit can be installed in this compartment. The space that has been made available can also be used to add an extra function to the LED module, e.g. a sensor, speaker, camera. The light of the LEDs does not enter this central compartment and cannot interfere with the functioning of the parts installed in the space that has been saved.

This is an advantage, particularly when an optical sensor has been placed in the space that has been saved. Examples of optical sensors are cameras, FIR sensors, motion sensors, and some smoke sensors.

The reflector cups preferably overlap each other. Having the reflector cups overlap results in a better light profile and enables the module to be made slightly smaller.

The module preferably contains a diffuser between the reflector cups and the second reflector compartment.

Alternatively, the module contains a diffuser at the front side of the communal reflector compartment.

The LED module preferably contains a heat sink with a recess for a reflector cup. A reflector cup on the side directed towards the LED preferably has a longitudinal opening.

It is noted here that LED modules containing a ring of LEDs are described in

EP2034234A1, US72441019B1 and US2004095763. However, none of these modules has a communal reflector compartment with a raised edge enclosing a central compartment, the central compartment of which is screened off from the light of the LEDs by the raised edge of the reflector compartment. Also, no mention is made of a sensor in the central compartment. Brief description of the drawings

The invention is described in further detail below by means of examples of embodiments of the LED module according to the invention with reference to the drawings, in which:

Figure 1 shows a perspective view of an LED module according to the invention with a power supply;

Figure 2 is a more detailed perspective view of an LED module according to the invention;

Figures 3 A and 3B show two examples of a reflector for an LED module according to the invention;

Figures 4A to 4C are views of a reflector for an LED module according to the invention;

Figure 5 is a cross-sectional view of a reflector for an LED module according to the invention;

Figure 6 is another example of a module according to the invention. The figures are exemplary figures, wherein, as a rule, like numerals denote like elements.

Detailed description of the drawings Figure 1 shows a perspective view of an embodiment of an LED module according to the invention with a power supply.

The LED module contains a PCB 1 onto which LEDs have been fitted. A reflector 2 has been installed in front of the PCB. The PCB is attached to a heat sink 3 to dissipate heat. In this example a screening glass 4 has been fitted in front of the reflector 2 to prevent the inside of the reflector from getting dirty, resulting in a decrease in light output. A diffuser 5 has been placed in the reflector in this example of embodiment. This is an optional application, depending on the extent to which one would want to target the bundle of light rays. The diffuser is preferably of a matt colour to optimally mix the light and it preferably has a light loss of less than 15%.

Power is supplied via a secondary connection cable 8 and a mains plug 6 for the 230V power mains and a 230V/24V power supply unit 7.

The intention is to achieve the greatest possible space internally in the LED module in order to integrate an electronic circuit. The features sometimes require more than the customary two current wires (+ and - wires) to the power supply unit. Relocating some of the electronic components from the power supply unit to the LED module enables the use of only two wires to be maintained. In this embodiment a female socket 11 has been integrated at the rear of the heat sink enabling different cable diameters and cable grades to be connected to it.

Due to the ever greater miniaturisation of electronic circuits, in the future it will probably be possible to drop the 230V/24V power supply and make a direct 230 V connection to the module. An enlarged compartment for an electronic circuit by means of a second PCB that is connected to the first PCB by means of a plug also offers the opportunity of installing an extra component (e.g. a sensor or camera 12) at the front of the lamp, which is screened off from the light of the LEDs, enabling this extra component to work properly. As the light of the LEDs in the ring does not enter the compartment, this light cannot negatively affect the functioning of a component installed in the compartment. This is specifically important for optical sensors such as cameras, FIR sensors and some smoke sensors.

However, to enable the rapid usability of LED lamps in practice, it is important that the LED module is not significantly larger than the existing halogen lamps.

The outer dimensions of the existing halogen lamps have been laid down in standards ("lamp outlines") and, consequently, it is important that the LED modules comply with these outlines so that rapid exchange is possible without having to buy a new light fixture.

The invention provides an LED module that makes this possible.

Figure 2 shows an LED module according to the invention with more details.

The PCB 1 has been fitted with LEDs 9. The PCB has also been fitted with electric circuit 10 and an extra feature 12, a PIR (Pyroelectric Infrared) sensor 12 in this example of embodiment. In this embodiment the wall of a reflector cup is constructed such that a bundle of light of 17° or less, e.g. 12° (narrow spot) is created.

A diffuser enables the width of the bundle to be expanded from 17° or 12° to 25-30° (spot) or from 17° to 50-60° (flood). This broadening of the bundle is accompanied by a loss of light of less than 15%, and preferably less than 10%; In addition, the diffuser hides the reflector cups and LEDs from view and creates a calm and homogeneous circle of light.

Figures 3 A and 3B show two examples of a reflector for an LED module according to the invention. The reflector 2 contains a number of cup-shaped reflector cups 13 that have an opening for an LED on their lower side. The reflector also contains a second communal reflector compartment 14. This configuration enables a targeted, more or less even bundle of light rays to be obtained, in situations where the LEDs and the reflector need less space. A compartment has been left open in the centre of the LED module. Some of the electronics which are normally contained in the power supply unit can be installed in this compartment. The available compartment can also be used to add an extra function to the LED module. The second reflector compartment 14 also offers the possibility, in embodiments, to broaden the bundle of light by placing the diffuser 5 at the transition of the reflector cups to the second reflector compartment. Placing the diffuser in the communal compartment reduces the risk of being blinded. When looking at the lamp from a diagonal angle the diffuser should preferably be placed as deeply as possible into the reflector. In preferred embodiments the diffuser can also be placed at the front of the lamp so that the light can first already be mixed in the communal reflector compartment and then it can be mixed further by the diffuser 5. The distance has been chosen such that the outlines of the existing halogen lamp are not exceeded. Not exceeding the outlines is made easier by not choosing standard high-power LEDs (>1 W), but deciding on one size smaller middle power LEDs (0.3W-0.7W) instead. The reflector cups that can be placed around these smaller LEDs can then be smaller. Figures 3 A and 3B show reflectors with diameters of approx. 50 mm and approx. 100 mm respectively. The number of reflector cups is approx. 12, e.g. 10 and 20 respectively. To enable different bundle widths to be created, it is a good idea to construct the reflector cups such that a small bundle of light (10-15 or 15-17°) can be created. A diffuser can be used to enlarge the bundle of light. Using three different reflector cups for different bundle widths is possible, but this would lead to more stock inventory and higher investments. The shapes of the three cups would then be different and there might also be a problem when gluing the reflectors and/or the reflector cups onto the crown-shaped heat sink. The parabolic shape of the 12° variety fits against the crown very nicely so that a neat gluing surface is created. Starting from a parabolic shape for the reflector cup, the height of the wall or the reflector cup can be experimented with. It has been found that the higher the cup, the narrower the bundle of light became. At a height of more than 9 mm there is hardly any effect left and that explains why this dimension has preferably been selected.

To make sure that the user does not look into the sharp light, it would help to place the ring of reflector cups as deeply as possible without it protruding beyond the lamp outlines. The height of the second mixing chamber then is at approx. 6 to 10 mm.

Placing a lot of LEDs in the circle still helps to generate as much light as possible. The inventor has realised that having the reflector cups overlap has little influence on the total bundle of light, but did cause the light output to increase and had the added benefit of creating a more continuous circular lamp instead of individual points of light.

Another advantage of the use of more LEDs is that the heat can be dissipated to the heat sink 3 better and more evenly.

To make the surface of the heat sink 3 as large as possible, crown-shaped protrusions have been fitted around the reflector 2.The heat sink continues all the way to the front side so that the heat can also be dissipated via the light fixture which, as a rule, is also metal. If the front side of the heat sink had been made of plastic, this plastic would act as a bottleneck for the conduction of the heat to the light fixture intended to enlarge the heat dissipation capacity. An additional advantage is that this enables the reflector 2 to be securely glued at that position so that the end user cannot open it and cannot reach any live components.

The communal ring-shaped reflector compartment 14 has an outer wall 15a and an inner wall 15b. The inner wall 15b encloses a central compartment 16. While in use, the light of the LEDs does not enter the central compartment 16 due to the screening action of the inner wall 15b. Some of the electronics which are normally contained in the power supply unit can be installed in the central compartment 16. The space that has been made available can also or additionally be used to add an extra function to the LED module, e.g. a sensor, speaker, camera.

The light of the LEDs does not enter this central compartment and cannot interfere with the parts installed in the central compartment 16.

This is an advantage, particularly when an optical sensor has been placed in the space thus saved. Examples of optical sensors are a camera 12, FIR sensors, motion sensors, and some smoke sensors. The wall 15b screens off the optical sensor from the light of the LEDs so that this does not interfere with the operation of the optical sensor 12. This brings great benefits, especially when sensors are used for surveillance purposes, such as security cameras and/or motion sensors:

- no separate sensor is needed, the sensor is integrated into the LED module

- the object or person to be monitored is always properly lit

- the presence of the sensor while in use cannot, or only with great difficulty, be detected by the naked eye by people. One would have to look directly into the light for this which would blind the eyes. Therefore, people with bad intentions who want to approach an object that is to be guarded cannot see that the module, when in use, has been fitted with an optical sensor or, if there are more modules, which module has been fitted with an optical sensor.

In embodiments the LED module can be fitted with both a motion sensor and a camera. A set of LED modules can also be used, with at least one of the modules of the set being provided with a motion sensor and at least one other one with a camera. To prevent the risk of danger, a set of LED modules can also be used, with one of the modules being provided with a smoke detector and at least one other one with a camera. The location of any fire that breaks out can then immediately be identified.

Figures 4A to 4C are different views of a reflector for an LED module according to the invention. Figures 4B and 4C show that the reflector cups overlap in the overlap zone 17. To ensure good heat transfer from the PCB to the heat sink, the PCB is screwed down with a number of screws, e.g. 3. A longitudinal opening 18, see figure 4C, can be made on the lower side of every reflector cup to make the screw head fit neatly between all the reflector cups as desired.

The advantage of placing the screws between reflector cups over applying screws to the centre of the PCB is that precious space is won for the electronic components.

Figure 5 shows a cross-sectional view of a reflector for an LED module according to the invention.

The sizes are also shown here schematically. I represents the depth of the reflector, II the size of the overlap and III the height of the second reflector compartment.

The total depth (I + III) is preferably between 15 and 19 mm, preferably approx. 17 mm, with a margin of approx. 0.5 mm. The ratio between the dimensions I and III is preferably between 0.7 and 1.5. The ratio between the depth of the reflector cup and the depth of the second reflector compartment is then between 0.7 and 1.5. In this example, I is approx. 9 mm and III approx. 8.3 mm. The reflector cups provide a targeted bundle of light, while the communal second reflector compartment ensures that the light is mixed. A very short second reflector compartment gives too little mixing, whereas the disadvantage of a compartment that is too long is that the lamp outlines are exceeded. The ratio between the depth II of the overlap between reflector cups 13 and the depth I of the reflector cups is preferably between 0.2 and 0.4. In this example II is approx. 2.6 mm. Too large an overlap causes the light to spread more. Preferably both depth ratios are complied with.

The communal reflector compartment is preferably constructed as a channel with the width IV of the channel being between 12 and 18 mm. The diameter V of the reflector is preferably between 50 and 100 mm, depending on the type of LED module. These dimensions yield a good light image and enable sufficient space to be saved in the centre of the LED module for electronics and/or extra features.

It will be clear that the invention is not limited to the embodiments of the invention described here.

Figure 6 is another example of an LED module according to the invention. This module is different from the module shown in figure 1 in that a wall of the heat sink serves as a part of the communal reflector compartment. In this example the wall 15b is a part of the heat sink. The reflector compartment is formed by a wall of the heat sink and walls of reflector 2. In this example, reflector 2 does not have the outer wall 15a, but does have the inner wall 15a.

The module can be provided with a temperature sensor, such as a thermistor which can be used to keep the operating temperature below a certain temperature, e.g. below 75 °C at the location of the sensor, and preferably below 70 °C. A signal from the temperature sensor can be supplied to a control circuit for the sensor. In an example of embodiment the thermistor is fitted between the LEDs. The thermistor signal is an indication of the temperature. This signal is supplied to a control circuit for the sensor, e.g. a microprocessor. For example: Sensor 12 is a motion sensor. A motion sensor generates a signal. To prevent the system from reacting to every movement, even that of a small object such as a fly or a moth flying around or mouse running around, the signal of the motion sensor is compared to a "threshold". Only if the signal of the motion sensor is greater than the threshold will a movement be registered and an action follow, such as the light and/or cameras switching on or a signal being given to a security switchboard. The sensitivity of the motion sensor depends on temperature, with a higher temperature in one example yielding lower sensitivity, i.e. the same movement of an object at a higher temperature resulting in a smaller motion sensor signal. The thermistor signal is supplied to the control circuit which sets the threshold as a function of the thermistor signal, i.e. as a function of the temperature in the module, where in this case the threshold is decreased if the temperature increases. This can be configured in hardware or in software form.

This example features a motion sensor, but the same principle can be used for other sensors, such as smoke sensors or cameras.

Claims

Claims:

I . An LED module containing a number of LEDs (9) and a reflector (2) to reflect the light emitted by the LEDs, characterized in that the LED module contains a ring of LEDs with the module containing a reflector cup (13) for every LED and with a communal ring shaped reflector compartment (14) positioned in front of the set of reflector cups, and with the ring-shaped reflector compartment containing a raised edge (15a) that encloses a central compartment (16), screened off from the light of the LEDs.

2. An LED module as claimed in claim 1 , characterized in that the module contains a sensor (12) in or on the central compartment (16).

3. An LED module as claimed in claim 2, characterized in that the sensor is an

optical sensor.

4. An LED module as claimed in claim 3, characterized in that the optical sensor is a camera (12).

5. An LED module as claimed in any of the above claims, characterized in that the module has a temperature sensor whose signal is supplied to a control circuit for the sensor.

6. An LED module as claimed in claim 1 , characterized in that the reflector cups overlap each other (17).

7. An LED module as claimed in claim 5, characterized in that the ratio between a depth (II) of the overlap between reflector cups and a depth (I) of the reflector cups is between 0.2 and 0.4.

8. An LED module as claimed in one of the above claims, characterized in that the module contains a diffuser (5) between the reflector cups (13) and the second reflector compartment (14) or in the reflector cups (13).

9. An LED module as claimed in one of the above claims, characterized in that the LED module contains a heat sink (3) in an opening for a reflector cup.

10. An LED module as claimed in one of the above claims, characterized in that the LED module contains a metal heat sink that continues all the way to the front side.

I I . An LED module as claimed in one of the above claims, characterized in that a reflector cup on the side directed towards the LED contains a longitudinal opening (16).

12. An LED module as claimed in one of the above claims, characterized in that the ratio between a depth (I) of the reflector cups and a depth (III) of the second reflector compartment is between 0.7 and 1.5.

13. An LED module as claimed in one of the above claims, characterized in that the second reflector compartment is constructed as a channel with the width (IV) of the channel being between 12 and 18 mm.

14. Lamp containing an LED module as claimed in one of the above claims.

15. Reflector apparently suited to an LED module as claimed in one of the above claims.