WO2013183987A1

WO2013183987A1 - Led module and lamp comprising an led module

Info

Publication number: WO2013183987A1
Application number: PCT/NL2013/000030
Authority: WO
Inventors: Quinten Van De Vrie; Petrus Johannes KOOMEN; Cornelis Dirk DE HAAN
Original assignee: Leds Progress Holding B.V.
Priority date: 2012-06-07
Filing date: 2013-05-29
Publication date: 2013-12-12
Also published as: NL1039662C2

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 collection of 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. The LED module contains a slot antenna 17 on the raised edge.

Description

Led Module and lamp comprising an LED module. Field of the invention. The invention concerns an LED module comprising a number of LEDs and a reflector to reflect the light emitted by the LEDs and a raised edge enclosing a central compartment.

Background of the invention. An LED module as described in the first paragraph is known from the Dutch patent

NL 1038327. The LED module contains a number of LEDs and a reflector to reflect the light emitted by the LEDs. The LED module contains a ring of LEDs and a raised edge within the ring of LEDs, enclosing a central compartment. As LED modules often form part of a larger unit, like a security unit, communication with the LED module is important.

An objective of the invention is to provide an LED module of the type referred to in the first paragraph that allows good communication with the LED module.

Summary of the invention.

To this end, the LED module according to the invention is characterized in that the raised edge is provided with a cylinder-shaped antenna for wireless communication from and to the LED module and in that the antenna is a slot antenna.

Since communication is wireless, no connecting wires are necessary to enable communication.

Providing a cylinder-shaped antenna on the raised edge enables reliable wireless communication both between an LED module and another device and between two or more LEDs. The radiation pattern of the slot antenna contributes to good communication and little interference to electronics present in the module. The cylinder-shaped antenna is preferably fitted in a ring-shaped slot in the raised edge.

More preferably, the cylinder-shaped antenna is provided on an outside of the raised edge.

Even more preferably, the cylinder-shaped antenna comprises two or more sub-rings.

A sensor is preferably provided inside the raised edge, for example an optical sensor. Examples of optical sensors are cameras, PIR sensors, motion sensors, and some smoke sensors.

It is noted that an LED module with an antenna is known from the patent specification

WO2010140136. This patent specification describes an LED module without a raised edge inside a ring of LEDs and describes an antenna placed around the LEDs. The antenna in WO 2010140136 is designed in a flat plane and not as a cylinder-shaped antenna. The advantage of placing an antenna inside the ring of LEDs as in the invention is that the antenna does not change the appearance of the LED module as a whole. A flat antenna as known from

WO2010140136 radiates forwards, in a narrow bundle. A cylinder-shaped slot antenna as in the invention has wider radiation, but oriented to the sides. This improves communication between LED modules and between an LED module and another device. This also reduces the interference to any electronic components located within the LED.

A rear light for a car is known from WO2006014069. This rear light is fitted with a number of separate LEDs. The rear light also is provided with a rear sensor that enables the distance to an object to be measured using microwave radiation. To this end, the rear light is provided with a transmitting and receiving antenna to emit a microwave signal and receive the microwave signal. A warning signal can be emitted depending on the distance. Although the two systems, rear light and microwave sensor, are integrated within a single housing, they do not work together; the receiving antenna does not send any signals from and to the LED module. The transmission and receiving antenna has been printed on a circuit board.

Brief description of the drawings

The invention is described in further detail below by means of exemplary

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

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

Figure 4 is a cross-sectional view of a reflector for an LED module according to the invention;

Figure 5 is a film with on it a slot antenna to be wound around the raised edge;

Figure 6 is a radiation pattern when using an antenna in a flat plane;

Figure 7 is a radiation pattern for a slot antenna on the raised edge. 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 known from the Dutch patent NL 1038327.

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 embodiment. This is an optional application, depending on the extent to which one would want to focus 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 is provided with sometimes require more than the customary two power 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 continued. In this embodiment a female socket 1 1 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 further 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, screened off from the light of the LEDs, enabling this extra component to work well. 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, PIR sensors and some smoke sensors.

However, to enable the rapid deployment 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 dimensions so that rapid exchange is possible without having to buy a new luminaire.

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, in this embodiment a PIR (Pyroelectric Infrared) sensor 12.

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 at their lower side. The reflector also contains a second communal reflector compartment 14. 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 in the reflector. In preferred embodiments the diffuser can also be placed at the front of the lamp so that the light can first be already mixed in the communal reflector compartment and then by the diffuser 5. Preferably, the entire unit does not exceed the outlines of the existing halogen lamp. 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. Figures 3A 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 5 can be used to enlarge the bundle of light.

To make sure that the user does not look into the sharp light, it is best 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 is then at approx. 6 to 10 mm.

Placing a lot of LEDs in the circle helps to still generate the maximum light possible.

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

The communal ring-shaped reflector compartment 14 has a raised edge with 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 available compartment can also, or furthermore, 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 compartment that has been left open. 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 visually detected by people. One would have to look directly into the light for this. However, this would blind the eyes, so that 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 fire, 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. If fire breaks out its location can then immediately be identified.

Particularly when using a sensor in the central compartment, it is important that good communication with the LED module can be provided to engage and disengage electrical signals. Electrical signals may be signals to activate functions, like activating the LEDs, or the sensor or signals emanating from a sensor, like camera signals. To this end, the LED module according to the invention is characterised in that the raised edge is provided with a cylinder-shaped antenna 17 for wireless communication from and to the LED module.

An antenna in this position offers a good signal without disturbing the functions of the other elements, like electronics. A signal emitted by the antenna can easily be received across a wide range of reception.

Fitting a cylinder-shaped antenna to the raised edge enables reliable wireless communication both between an LED module and another device and between two or more LEDs. The antenna is a slot antenna. The radiation pattern of a slot antenna on the raised edge is mainly oriented sideways. This decreases the antenna causing any interference to the electronics present in the LED module. This makes it possible to decrease the distance between the electronics and the antenna and to make a compact design. The antenna can be placed in the LED module. The radiation pattern improves communication between LED modules and from and to LED modules.

More preferably, the cylinder-shaped antenna is applied to an outside of the raised edge.

Even more preferably, the cylinder-shaped antenna consists of two or more parts.

Figure 4 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 somewhere 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 somewhere 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 and 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 somewhere 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 rV 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 is provided with.

The LED module is provided with a cylinder-shaped tube 18 with cylinder-shaped antennas 17a and 17b on it that, together with an edge 17c on top of the raised wall wand 15b, form the antenna 17. The antennas may partially be attached to film, with the film being applied to the raised edge 15b. In this example, the antenna contains two parts, the film with on it the antenna parts 17 a and 17b, and a conductive ring 17c on the top side of the raised edge. The antenna 17 is, for example, connected to, for example, a control unit 19 by means of a coaxial cable Coax. This control unit 19 receives signals from the antenna and can also ensure that signals are transmitted via the antenna 17. There are slots S between the parts 17a, 17b and 17c of the antenna. Signals that are received from the antenna can be used, for example, to engage a sensor 12.

An LED module according to the invention may be part of a set of LED modules, for example with one of the LED modules comprising a motion sensor in compartment 16. As soon as this sensor detects movement this will cause a signal to be transmitted via antenna 17. Another LED unit of the set of LED modules receives this signal and switches on a camera located in the compartment 16 of the LED module in question. Furthermore, the LED lamps can also be activated.

The mechanical construction of the LED module is very compact, making it a difficult environment for finding an adequate high-frequency solution for a roughly omnidirectional antenna. The frequency is, for example, in the area between 1 and 10, for example between 2 and 3 GHz.

Figure 5 shows a film F with on it the parts 17a and 17b of the antenna 17, separated by a slot S. This is an example of a slot radiator. In essence, a slot radiator is an antenna with a slot in it. The slot antenna extends along the raised edge and the slot S in the antenna forms part of a ring.

This solution was found by choosing an approach consisting of simulation followed by practical tests. The film F is bent around the raised edge 15b and is fitted such that the ring 17c roughly matches the raised edges of part 17a. This creates a further slot S between the parts 17b and 17c.

Several tests have revealed that applying the slot antenna, which has been bent to a round shape, to the outer wall (figure 3, 15b) of the upper reflector wall yields very good results. In this example, the slot antenna chosen (fig. 5) has an extra connection point (17b) in its centre. The advantage of this is that the dimensions of the total antenna can be reduced relative to an antenna that contains only the parts 17a and 17 c, as a result of which it is easier to integrate the antenna 17 into the LED module. The slot antenna (fig. 5) is powered by a coaxial cable (Coax), that also enables the signals received to be passed on. The inner wire is connected to the central antenna connection point (17b) and the outside is connected to the metal layer under the first slot (17a).

To increase the bandwidth of the antenna, and to achieve optimal adjustment to the working frequency, a capacitor is preferably attached between the central connection point (17b) and to the metal layer under the first slot (17a). This capacitor is preferably an SMD capacitor (C housing 0402). As a result of this, no adjustment circuit is necessary on the PCB.

A chrome part (fig. 5, 17c) has been applied around the PIR sensor. This serves as the upper part of the antenna and it also serves an aesthetic purpose. The cylindrical shape of the antenna offers the advantage that the sensitivity and the transmission power of the antenna is roughly identical in all directions. This is an advantage if it is not known in advance where parts with which communication will have to take place, like control equipment or other LED modules, will be located in practice.

Figure 6 shows the radiation pattern of a flat antenna as known from WO2010140136. The antenna radiates in a rather narrow bundle along the optical axis of the LED module.

Although this is not shown in the figure, this also means that the antenna radiates backwards, i.e. to the electronics present in the LED module, to a similar extent. As this may cause interference for the electronics, the antenna has to be placed rather far from the electronics, for example in a part that protrudes beyond the actual housing. This makes the LED module longer, making ceiling integration of standard designs of the module difficult. The antenna of WO2010140136 is constructed on a PCB that is located transversally to the optical axis of the LED module. The antenna then extends in a plane that is oriented transversally to the optical axis. The antenna then transmits a bundle of signals forwards along the optical axis, at an angle of approx. 30-35 degrees. An antenna that extends in a plane that is oriented

transversally to the optical axis yields such a radiation pattern. Communication with other LED modules and other equipment then mainly takes place by reflection. Communication may be impaired if the LED module is integrated into a ceiling and the floor is provided with materials that strongly absorb radio radiation. Figure 7 shows the radiation pattern for an LED module according to the invention. The antenna is provided on the raised edge and is a slot antenna. The radiation pattern of a slot antenna that extends on the raised edge is distinctly different from that of an antenna as known from WO2010140136. Slot antennas mainly radiate in a direction transversal to the slot, i.e. more sideways than forwards. The housing and the slot antenna together cause the radiation to be mainly transmitted as a ring of radiation around the LED module. Since the slot antenna causes less interference to the electronics, a more compact design and/or stronger radiation are possible. Communication with equipment, which is often located along walls, is better. Communication between LED modules is also improved.

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

The module can be provided with a temperature sensor, such as a thermistor. It can be used to keep the operating temperature below a certain temperature, e.g. below 75°C at the location of the sensor, preferably below 70°C. A signal from the temperature sensor can be supplied to a control circuit for the sensor. In an exemplary 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 that is flying around or a moving mouse, 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 can 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 is provided with a motion sensor, but the same principle can be used for other sensors, such as smoke sensors or cameras.

Claims

Claims:

1 LED module comprising a ring of LEDs and a reflector to reflect the light emitted by the LEDs and a raised edge (15b) inside the ring of LEDs, enclosing a central compartment, characterized in that the raised edge is provided with a cylinder-shaped antenna (17) for wireless communication from and to the LED module and in that the antenna is a slot antenna.

2 LED module as claimed in claim 1 , characterized in that the cylinder- shaped antenna (17) is applied to an outside of the raised edge (15b).

3 LED module as claimed in claims 1 or 2, characterized in that the slot antenna is provided with a lower part (17a), a central part (17 b) and an upper part (17c) separated by slots (S).

4 LED module as claimed in claim 3 characterized in that a capacitor (c) has been fitted between the lower and upper parts.