Illumination module

A light emitting diode (LED) module is provided that includes a base and a cover. Circuitry is provided on the base. An LED array is provided on the base and is coupled to the circuitry, which in an embodiment may convert AC line voltage to DC voltage. The LED module can be configured to take up minimal space while providing desirable light output.

FIELD OF THE INVENTION

The present invention relates to field of lighting using a light emitting diode (LED), more specifically to the field of modular LED-based solutions.

DESCRIPTION OF RELATED ART

The efficiency of the light emitting diode (LED) has been substantially increased over the past decade and consequentially, LEDs are known to be suitable for using in providing general illumination. One issue that exists, however, is packaging LEDs. LEDs, while efficient, require careful thermal management to avoid negatively impacting the potential long life that would otherwise be possible. In addition, as LEDs require current in one direction to function, AC voltage needs to be converted to DC voltage (at least effectively converted). Furthermore, it would be beneficial to provide a LED module in a small package size. Emitters have been used as they consist of a single LED chip but such devices tend to be limited in the amount of light output (typically less than 200 lumens). To provide more lumens, reasonably compact devices such the device depicted inFIG. 1have been proposed. However, these devices still require DC voltage and usually are constructed (often they use metal clad PCB base) such that they are incompatible with line voltage requirements. Thus, existing designs fail to provide a compact, high light output system that would be compatible with AC line voltage. Therefore, certain individuals would appreciate an improved LED module.

BRIEF SUMMARY

A light emitting diode (LED) module is provided that includes a base and a cover. Circuitry is provided on the base. An LED array is provided on the base and is electrically connected to the circuitry, which in an embodiment may convert AC line voltage to DC voltage. The cover can include a non-reflective angled surface that is designed to have minimal impact on the shape of light emitted from the LED array.

DETAILED DESCRIPTION

The detailed description that follows describes exemplary embodiments and is not intended to be limited to the expressly disclosed combination(s). Therefore, unless otherwise noted, features disclosed herein may be combined together to form additional combinations that were not otherwise shown for purposes of brevity.

FIGS. 2A-13illustrate embodiments of a LED module. One beneficial feature of the depicted design is that a cover60is provided with an angled surface62that acts substantially as a non-reflective surface. In other words, an LED array100has a light block110that provides the illumination and extends through aperture94in base40and the angled surface62is designed to substantially not shape the light emitted from the light block110. Thus, if the light block110naturally provides a distribution of about 60 or 90 or 110 or some other angle, then the angled surface would be configured to be at that corresponding angle or at a slightly greater angle. In general, the angled surface of a non-reflective surface can be configured to reflect less than 10 percent of the light being emitted and preferably will reflect less than 5 percent of the light being emitted.

Of course, as can be readily appreciated, the cover could also include a reflector and/or lens that purposefully shapes the light. In such a configuration, the cover would not have a non-reflective angled surface but could otherwise provide other benefits discussed herein. In addition with a cover that shapes the light (e.g., focuses the light) or that includes a simple transparent lens, it would be possible to provide a LED module that would be considered touch-safe.

As can be appreciated, the LED module includes a base40that supports the LED array100. The base40can further support circuitry that converts AC voltage to DC voltage. As depicted, for example, the base40allows for AC line voltage (e.g., 110 VAC) input via conductors11,12and converts the AC voltage to DC voltage so that the LEDs provided by the light block110can be powered in an effective manner. The depicted embodiment includes a fuse83, a rectifier84, a voltage surge suppressor85, and a controller86that actuates a MOSFET power source87. The depicted configuration has multiple taps88on the base40that are used to selectively power pads111,112,113, and114of the LED array100and each of the pads is coupled to a series of LEDs in the light block110. By selective powering of the different series of LEDs it is possible to provide illumination that is flicker-free to a user's eyes (e.g., any flicker present is not perceptible to a user). Chips that can provide this type of control include designs such as is provided by EXCLARA's EXC100 driver. Thus, the depicted design allows for efficient use of AC voltage and to provide substantially constant illumination to the user's eyes in spite of the fact that AC voltage fluctuates. Therefore, the depicted configuration provides pleasing illumination without noticeable flicker but does not require capacitors (which tend to be a failure point for any long-lasting system). Of course, the addition of capacitors can further optimize the performance of the system and may be useful for situation where dimming capabilities are desired but if provided, the capacitors could be smaller in size and more robust in design (for example, ceramic capacitors could be used in certain embodiments or the capacitors could be better cooled), thus still providing high durability and lower costs. In addition, the depicted system is suitable for manufacture in processes that utilizes wave solder techniques.

It should be noted, however, that a more conventional capacitor based power conversion system could be used if desired. Such a power conversion system (which would include a rectifier and a larger capacitor to stabilize the output) is more conventional and thus need not be discussed in detail herein as a large number of possible variations are available, it being understood that such a system would be larger in size than might otherwise be desirable

One benefit of the depicted design is that the base40is an insulative material that provides both structure rigidity and also supports circuitry70(which provides the desired control such as conversion from AC to DC). As can be appreciated, traces81,82provided on base40can electrically connect the various components. In an embodiment, the base40can be a plateable plastic and the traces can be provided via a known conventional LDS process. One benefit of the depicted design is that the base can be configured to be about 60 mm in diameter while the combination of the base and the cover can be about 10 mm high. Thus, the volume of the LED module can be less than 35,000 mm3while still providing greater than 500 lumens of output and also provide AC to DC conversion. In an embodiment the input AC voltage can be AC line voltage (e.g., 110 volts). And with the depicted embodiment, the volume can be less than 30,000 mm3while substantially avoiding light shaping due to the use of the non-reflective cover. Thus the depicted embodiment provides substantial benefits as compared to existing LED modules.

To provide appropriate thermal performance for a system that is cable of emitting more than 500 lumens and in embodiments can emit more than 700 or even more than 1000 lumens, the LED array100includes a substrate105that has low thermal resistance. In addition, a thermal pad20is positioned on a flange44that extends along a circumference and on a bottom of the base40and provides a thermal connection between the substrate105and a support surface. In an embodiment, the flange44and the substrate105can be configured so that both have a bottom surface on the same plane. Thus, the thermal resistance between the LED chips and the support surface on which the LED module mounts can be kept below 2 C/W and preferably below 1 C/W.

The thermal pad20is preferably electrically insulative but thermally conductive and thus, in combination with the cover and the base, forms a pocket of insulative material around the components provided on the base40. While the LED array100is configured to be positioned in a socket50that is in communication with the aperture94, the substrate105extends below the socket50so as to ensure good thermal connection to the thermal pad20. If desired, one or more heat pucks130can be provided on the bottom side of the base40and the heat pucks130can be in thermal communication with components positioned on the top side of the base40via thermal vias93. Thus, thermal management of the entire system is possible while ensuring desirable electrical isolation so that an AC compatible LED module with the desired size requirements can be provided.

FIGS. 14-15illustrate an embodiment of a LED module210with a lens295that is configured to shape light emitted from the corresponding LED array. The construction of the LED module210can be substantially similar to the LED module10except for the increased height of the cover260to allow for the lens295that is suitable to shape the light into a desired pattern. Thus, circuitry270is provided on the base240that can be similar to the circuitry provided in LED module10(although with additional space, additional components can be added if desired) and a thermal pad220. In either example, as can be appreciated, it would be possible to include an antenna and a wireless communication capable chip (such as a transceiver chip) that can receive and/or transmit commands via WI-FI or a ZIGBEE based protocol (or any other desirable protocol). Such a chip could be coupled to (or incorporated into) the controller and allow for wireless modification of the output of the LED module (e.g., to dim or turn the module on and off). Even with the taller embodiment that includes a light-shaping element such as lens295, however, the volume of the module could be less than 40,000 mm3.

Another embodiment of an LED module310is depicted inFIGS. 16-21. The LED module includes a base340, a cover360and a lens395. A thermal pad320is provided and optional power pins397extend below the thermal pad a distance than can be greater than 2 mm and more preferably more than 3 mm. It has been determined that such a construction can allow a socket (not shown) to be configured in a touch-safe manner such that an individual could safe place a finger in the socket without risking contact with a contact carrying a high voltage.

As can be appreciated, an optional channel343can be configured to receive a wire inserted into the channel (e.g., by including a conventional wire trap) such that the module can be easily assembled to a supporting surface and also easily be connected to a power source without the need to solder wires. In an embodiment the power pins could be omitted and the channel can include a trace that extends from the wire trap to the location where the trace can be coupled to a desired power supply position on the base340.

The construction of the module310can be similar to the construction depicted above. For example, the base340is depicted with a socket350that receives an LED array (such as LED array100) so that light block410can be position in a manner that allows for illumination to be emitted, however a lens is depicted as shaping the emitted light. The use of the lens tends to cause the LED module to grow in height and thus allows for more space to place circuitry inside the module. As discussed above, taps388allow for power to be selectively provided to different portions of the light block410. Circuitry, as noted above, can include voltage suppressor385, as well as controllers and communication chips (which can be provided separately or integrated together) that can be positioned near thermal vias393, which can be aligned with a heat puck130. The module310is also depicted as including capacitors399. Capacitors tend to be larger in size then other components and can be somewhat sensitive to heat. Therefore, a bottom surface130aof the heat puck130, a bottom surface105aof the substrate105and a bottom surface399aof the capacitor399can be aligned so as to be substantially planar in orientation such that the thermal pad320is effective to provide acceptable thermal transfer between a supporting surface and the corresponding bottom surfaces. Thus, the capacitor399can be positioned in an aperture400that allows the capacitor399to readily connect electrically to components positioned on a first side of the base340while also extending to the thermal pad on a second side of the base.

As can be appreciated, therefore, features of the depicted design allow for a more compact LED module that provides desirable illumination characteristics and can accept AC line voltage as an input. Numerous other benefits of the embodiments depicted herein can also be appreciated, depending on the desired configuration.

The disclosure provided herein describes features in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure.