LED lighting apparatus with flexible light modules

The present disclosure involves a street light. The street light includes a base, a lamp post coupled to the base, and a lamp head coupled to the lamp post. The lamp head includes a housing and a plurality of LED light modules disposed within the housing. The LED light modules are separate and independent from each other. Each LED light module includes an array of LED that serve as light sources for the lamp. Each LED light module also includes a heat sink that is thermally coupled to the LED. The heat sink is operable to dissipate heat generated by the LED during operation. Each LED light module also includes a thermally conductive cover having a plurality of openings. Each LED is aligned with and disposed within a respective one of the openings.

TECHNICAL FIELD

The present disclosure relates generally to light-emitting devices, and more particularly, to a flexible light-emitting diode (LED) light module used in LED lamps.

BACKGROUND

LED devices are semiconductor photonic devices that emit light when a voltage is applied. LED devices have increasingly gained popularity due to favorable characteristics such as small device size, long lifetime, efficient energy consumption, and good durability and reliability. In recent years, LED devices have been deployed in various applications, including indicators, light sensors, traffic lights, broadband data transmission, and illumination devices. For example, LED devices are often used in illumination devices provided to replace conventional incandescent light bulbs, such as those used in a typical street lamp. However, traditional LED lamps may suffer from drawbacks such as lack of flexibility, difficult maintenance, incompatibility with certain types of existing street light housings, and unsatisfactory waterproofing capabilities.

Therefore, while existing LED lamps have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect. LED lamps that can overcome the shortcomings of traditional LED lamps discussed above continue to be sought.

DETAILED DESCRIPTION

It is understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. Moreover, the terms “top,” “bottom,” “under,” “over,” and the like are used for convenience and are not meant to limit the scope of embodiments to any particular orientation. Various features may also be arbitrarily drawn in different scales for the sake of simplicity and clarity. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself necessarily dictate a relationship between the various embodiments and/or configurations discussed.

Semiconductor devices can be used to make photonic devices, such as light-emitting diode (LED) devices. When turned on, LED devices may emit radiation such as different colors of light in a visible spectrum. Compared to traditional light sources (e.g., incandescent light bulbs), lighting instruments using LED devices as light sources offer advantages such as smaller size, lower energy consumption, longer lifetime, variety of available colors, and greater durability and reliability. These advantages, as well as advancements in LED fabrication technologies that have made LED devices cheaper and more robust, have added to the growing popularity of LED-based lighting instruments in recent years. Nevertheless, existing LED lighting instruments may face certain shortcomings. Some of these shortcomings include lack of flexibility, difficulty of maintenance, incompatibility with certain types of existing street light housings, and unsatisfactory waterproofing capabilities.

According to various aspects of the present disclosure, described below is an improved LED lighting instrument20that substantially overcomes these shortcomings associated with traditional LED lighting instruments. Referring toFIG. 1, a diagrammatic fragmentary perspective view of a portion of the lighting instrument20is illustrated according to some embodiments of the present disclosure. In more detail, the portion of the lighting instrument20shown inFIG. 1is a lamp head of a street light. The lighting instrument20includes a lamp head housing30and a plurality of light modules40that are implemented inside the lamp head housing30. To provide more clarity, one of such light modules40is illustrated separately from the lamp head. The light modules40are separate and independent from one another. Each light module40can be individually installed within (or taken out of) the lamp head housing30. In some embodiments, each light module40can be secured to the lamp head housing30using a screw50(or another suitable fastening mechanism). In alternative embodiments, the light modules40can be secured to the lamp head housing30via screw-free mechanisms, which will be discussed in more detail below with reference toFIGS. 3A-3Band4A-4C.

FIGS. 2A and 2Bare more detailed perspective views of an example light module40A according to some embodiments.FIG. 2Ashows an exploded perspective view of the light module40A, andFIG. 2Bshows an assembled (or integrated) perspective view of the light module40A. The light module40A includes a plurality of semiconductor photonic devices, for example LEDs60, as light sources. Each LED60may include a p-type layer and an n-type layer, each of which contains a respective III-V group compound. Each LED60may also include a multiple quantum well (MQW) sandwiched between the p-type layer and the n-type layer. The MQW layer includes alternating layers of gallium nitride and indium gallium nitride. The p-type and n-type layers and the MQW layer may be formed by a plurality of epitaxial growth processes. The MQW emits light in response to an electrical voltage applied to the p-type and n-type layers.

The LEDs60are located on a substrate70. In some embodiments, the substrate70includes a Metal Core Printed Circuit Board (MCPCB). The MCPCB includes a metal base that may be made of Aluminum (or other alloys). The MCPCB also includes a thermally conductive but electrically insulating dielectric layer disposed on the metal base. The MCPCB may also include a thin metal layer made of copper that is disposed on the dielectric layer. In certain embodiments, the substrate70may include other suitable thermally conductive structures. The substrate70may contain active circuitry and may also be used to establish interconnections.

The LED60each have a primary lens (not illustrated herein) formed thereon. The primary lens may be directly mounted on the LED and may shape the pattern of the light emitted by the LED. In addition, the LEDs60are also each covered by a secondary lens80, which is positioned over the primary lens. The secondary lens80works in conjunction with the primary lens to further shape the pattern of the light emitted by the LED60into a desired light pattern. The secondary lenses80are reconfigurable. For example, the secondary lenses80may be replaced by other types of secondary lenses in order to adjust the output light pattern of the LED60.

The light module40A also includes a metal cover90disposed over the LED60. The metal cover90contains a plurality of openings100that are approximately aligned with the plurality of LEDs60, respectively. Alternatively stated, each LED60is disposed within a respective one of the openings100. In some embodiments, the openings100are each defined by sidewalls110that collectively form a polygonal structure, for example a rectangle. Each LED60is circumferentially surrounded by a respective one of the polygonal structures (i.e., openings).

The secondary lens80will be struck on the metal cover90by adhesive glue. These polygonal structures of metal cover90serve at least two purposes. First, they protect the secondary lens80and LED60therein from being damaged by external objects. For example, a projectile thrown toward the secondary lens80and LED60may be deflected by the sidewalls110of the metal cover90, thereby avoiding impact (and the consequent damages) with the secondary lens80and LED60. Second, the polygonal structures surrounding the LED60also function as reflector cups for the LED60. That is, the light emitted by the LED60may be reflected by the sidewalls110of the metal cover90toward a desired direction(s). Without a reflective structure, light may be emitted toward undesired directions, thereby weakening the intensity of the light output in the desired direction. The metal cover90is also thermally coupled to the LED60, and as such can be used to dissipate heat generated by the LED60.

A cable120is coupled to the metal cover90through a waterproof connector130. Wires such as electrical wires may be routed to the light module40A through the cable120and the waterproof connector130, so that electrical connections may be established between the LED60and external devices. The waterproof connector130prevents water (or other forms of moisture) from reaching inside the light module40A.

The substrate70on which the LEDs60are implemented is disposed on a thermal pad140. The thermal pad140has good thermal conductivity and may include a metal material. In this manner, thermal energy (i.e., heat) generated by the LEDs60during operation can be efficiently transferred to the thermal pad140.

The thermal pad140is surrounded and/or sealed by a gasket150. The gasket150is made of a waterproof material to prevent moisture from reaching inside the light module40A. Thus, the light module40A is independently waterproof.

The thermal pad140is also disposed on a on a thermal dissipation structure160, also referred to as a heat sink160. Since the thermal pad140has good thermal conductivity, it can transfer the thermal energy generated by the LED60to the heat sink160. The heat sink160contains a thermally conductive material, such as a metal material, to facilitate heat dissipation to the ambient atmosphere. To enhance heat transfer, the heat sink160also includes a plurality of fins170that protrude outwardly from a body of the heat sink160. The fins170may have substantial surface area exposed to ambient atmosphere to maximize the rate of heat transfer. The heat sink160(and the fins170) is discussed below in more detail with reference toFIGS. 8A and 8B.

Though not specifically illustrated inFIGS. 2A-2Bfor reasons of simplicity, it is understood that one or more fastening mechanisms (e.g., the screw50ofFIG. 1) may be used to secure the light module40A to a suitable housing, for example the lamp head housing30shown inFIG. 1. Thus, the light module40A can be easily installed into (or taken off from) the housing. A service technician merely needs to fasten (or release) the screw and the waterproof connector. This allows for easy maintenance of street lights in the field, especially in higher altitude situations above ground.

FIGS. 3A and 3Bare exploded and assembled perspective views of a light module40B according to some other embodiments of the present disclosure. The light module40B has similarities with the light module40A discussed above with reference toFIGS. 2A-2B. For reasons of clarity and consistency, similar components in both light modules40A and40B will be labeled the same herein. For example, the light module40B includes a plurality of LEDs60implemented on a substrate70. The LEDs60are covered by reconfigurable secondary lenses80. A metal cover90containing openings100is located over the LED60, wherein each LED60is disposed within one of the openings100. The LEDs60are thermally coupled to a heat sink160through a thermal pad140. The heat sink160contains a plurality of fins170to facilitate heat dissipation.

Unlike the light module40A, the light module40B employs one or more screw-free mechanism200to secure the light module40B to a suitable housing, for example the lamp head housing30shown inFIG. 1. In some embodiments, the screw-free mechanisms200include metal tenons (thereafter referred to as metal tenons200), which allow the light module40B to be secured to the housing30by a springing force.FIGS. 4A-4Cillustrate the metal tenons200from different perspectives in more detail. As is shown, a portion of the metal tenons200may be in physical contact with side walls of the heat sink160. Another portion of the metal tenons200may be in physical contact with the housing30. A springing force of the metal tenons200secures the heat sink160(and therefore the light module40B) to the housing30. In other words, the light module40B may be effectively clamped to the housing30through the springing force.

Thus, to install the light module40B into the housing30, the service technician simply needs to position the light module40B and the metal tenons200until the metal tenons can be “clamped in” or “clamped down.” On the other hand, to release the light module40B from the housing30, the service technician simply needs to unclamp the metal tenons200. The service technician does not need to carry any tools such as wrenches or screwdrivers with him. Such design further simplifies the maintenance process. In some alternative embodiments, the screw-free mechanism200may include clampers (e.g., on one of the side fins170of the heat sink160), or a slide groove and a fix pin.

Referring back toFIGS. 3A-3B, another difference between the light modules40A and40B is that the plurality of LEDs60in the light module40A is arranged in a single row of vertically-oriented array, whereas the plurality of LEDs60in the light module40B is arranged in two rows of horizontally-oriented arrays. Other arrangements are envisioned in alternative embodiments. A light module may employ any suitable arrange configurations of LED depending on factors such as desired light pattern, light density, available space, and/or costs.

FIG. 5is an exploded perspective view of a light module40C according to some other embodiments of the present disclosure. The light module40C has similarities with the light modules40A and40B discussed above with reference toFIGS. 2A-2Band3A-3B. For reasons of clarity and consistency, similar components in all of the light modules40A-40C will be labeled the same herein. For example, the light module40C includes a plurality of LEDs60implemented on a substrate70. The LEDs60are covered by reconfigurable secondary lenses80. A metal cover90containing openings100is located over the LEDs60, wherein each LED60is disposed within one of the openings100. The LEDs60are thermally coupled to a heat sink160through a thermal pad140. The heat sink160contains a plurality of fins170to facilitate heat dissipation. Similar to the light module40B, the light module40C has two rows of horizontally-oriented arrays of LEDs60. And similar to the light module40A, the light module40C uses screws (rather than a screw-free mechanism) to secure itself to a housing. Thus, the light module40C may be considered a combination of the light modules40A and40B.

FIGS. 6A-6Cillustrate embodiments of a lamp head210within which the light modules40A,40B, or40C may be implemented. In more detail,FIG. 6Ais an exploded perspective view of different components of the lamp head210,FIG. 6Bis a top view of the lamp head210, andFIG. 6Cis a perspective view of the lamp head210. The lamp head210may be considered an embodiment of the lighting instrument20ofFIG. 1.

The lamp head210includes a fixture220, which may be a board or a plate. In some embodiments, the fixture220includes a thermally conductive material such as metal. A plurality of light modules40are attached to the fixture220, either through screws or a screw-free mechanism discussed above. A housing structure230provides cover for the light modules40. The fixture220and the housing structure230collectively at least partially enclose the light modules40therein. The fixture220may be considered a part of the housing structure230. In some embodiments, the housing structure230is a cobra head housing for tradition street lighting. The cobra head housing may have a shape resembling the head of a cobra. Other types of street lighting housing structures may be used in alternative embodiments. The housing structure230may also include a perforated plate240for better air ventilation, so as to optimize heat dissipation. The lamp head210may also contain a power module250, which is also housed within the housing structure230. The power module250may include electrical power circuitry for providing and/or routing electrical power to the light modules40.

FIG. 7is a diagrammatic fragmentary cross-sectional side view of the light module40according to some embodiments. The light module40contains an LED60that emits light. The LED is disposed on a substrate70, which is thermally coupled to a heat sink160through a thermal pad140. A secondary lens80is disposed above the LED60and shapes the light pattern emitted by the LED60. An optical glue260fills the space between the LED60and the secondary lens80. A metal cover90is disposed above the secondary lens80and protects the lens80and the LED60from external impact. The metal cover90includes an opening100aligned with the lens80or the LED60. Alternatively stated, the lens80and the LED60are disposed within the opening100. The opening100is defined by sidewalls110. The sidewalls110are operable to reflect light, for example reflecting light270A emitted by the LED60as light270B. Since the sidewalls110of the metal cover90can be used as reflective structures, no additional reflective structures need to be implemented, thereby saving fabrication costs.

FIGS. 8A and 8Bare diagrammatic perspective views of different embodiments of the heat sink160. Referring toFIG. 8A, the heat sink160A includes a main body275and a plurality of fins170A protruding outwards from the main body275. The fins170A each have a recess280. In other words, the fins170A are each approximately “U-shaped.” The recesses280may be approximately aligned with one another, so that an air flow path is formed by the aligned recesses280collectively. In this manner, air flow in the heat sink160is enhanced, thus further increasing heat dissipation efficiency.

Referring toFIG. 8B, the heat sink160B includes a plurality of fins170B protruding outwards from the main body275. The fins170B also each have a recess280. The fins170B are also approximately “U-shaped” and aligned with one another. Therefore, similar to the heat sink160A, the heat sink160B also has enhanced heat dissipation characteristics due to better air flow. In addition, the fins170B of the heat sink160B each include a plurality of outwardly-protruding branches290. These branches290further increase heat dissipation efficiency of the heat sink160B, since they keep the same air flow rate and add additional exposure area to the heat sink160B.

FIG. 9is a flowchart of a method300for fabricating a lighting apparatus using a semiconductor photonic device as a light source according to various aspects of the present disclosure. The method300includes a block310, in which an LED array contains a plurality of LEDs are mounted on a board. In some embodiments, the board includes a MCPCB board, and the LEDs are each covered by a reconfigurable secondary lens. The method300includes a block320, in which the LED array is coupled to a metal cover and a heat sink, thereby forming an LED light module. The metal cover includes a plurality of openings surrounding the LEDs, respectively. The openings are defined by reflective sidewalls of the metal cover. The sidewalls are operable to reflect light emitted by the LED. The heat sink has a plurality of fins that each have a recess therein. The recesses allow better air flow within the heat sink. The heat sink is operable to dissipate heat generated by the LEDs. The method300includes a block330, in which a plurality of LED light modules is installed in a street light housing. The LED light modules are separate and independent from each other. Each of the LED light modules has independent waterproofing capabilities. The street light housing may include cobra head housing in some embodiments.

Additional processes may be performed before, during, or after the blocks310-330discussed herein to complete the fabrication of the lighting apparatus. For the sake of simplicity, these additional processes are not discussed herein.

The lighting instrument20according to the embodiments disclosed herein offers advantages over existing semiconductor-based lighting products. It is understood, however, that not all advantages are necessarily discussed herein, and different embodiments may offer additional advantages, and that no particular advantage is necessarily required for all embodiments.

One advantage of the embodiments disclosed herein is the light modules allow for easy installation and maintenance. Traditional LED lamps usually involve a set of LEDs mounted on a single printed circuit board. Thus, the entire board may need to be taken out of the housing to repair a single component, which is cumbersome and costly. In comparison, the embodiments of the present disclosure allow multiple separate and independent LED light modules to be installed into a lamp head housing. The installation of the light modules is easy because it merely involves securing each module to the housing via a screw, or a screw-free mechanism in some embodiments. Servicing is made simpler as well, since if a component on a single light module needs to be repaired or replaced, only that light module needs to be taken out of the housing. To carry out the installation and servicing tasks, a technician needs only basic tools (e.g., wrench or screwdriver) or no tools at all. The simple installation and maintenance of the light modules is particularly advantageous in embodiments where the light modules are installed in street lights, because servicing the street lights typically involves high altitude operations. Thus, the easier and faster the installation and maintenance, the safer it is.

Another advantage of the embodiments disclosed herein is the enhanced thermal dissipation capabilities of the LED light modules. In some embodiments, the aligned recesses of the fins of the heat sink allow for better air flow, which increases the rate of heat dissipation. In some other embodiments, the fins of the heat sink also have protruding branches, which allows for better thermal convection and may reduce junction temperature. The metal cover also enables bidirectional heat dissipation, that is, the heat can be dissipated in one direction through the heat sink, as well as being dissipated in the opposite direction through the metal cover. Such bidirectional heat dissipation helps prevent ice buildup on the front side of the lamp in cold weather, since by dissipating the heat, the metal cover can melt ice or snow deposited on the metal cover or in its surrounding areas.

Yet another advantage of the embodiments disclosed herein is the improved optical design. For example, the secondary lens in conjunction with the primary lens can flexibly shape the light profile of the LED. The optical glue implemented between the secondary lens and the LED further increases the light output efficiency to as much as 100%. Furthermore, the fact that the metal cover can be used as light reflectors obviate the need to implement additional light reflectors, thereby simplifying lamp design and reducing fabrication costs.

Another advantage is attributed to the independent waterproofing capabilities for each LED light module, which reduces overall system failure risks. One more advantage pertains to the compatibility of the LED light modules with the cobra head street light housing, which is difficult to achieve for traditional LED lamps.

FIG. 10illustrates a simplified diagrammatic view of a lighting apparatus400that includes some embodiments of the lighting instrument20discussed above. In some embodiments, the lighting apparatus400is a street light. The lighting apparatus400has a base410, a body420(or post) attached to the base410, and a lamp head430attached to the body420. In some embodiments, the lamp head430includes a cobra head lamp. Light440is emitted from the lamp head430.

The lamp head430includes the lighting instrument20discussed above with reference toFIGS. 1-9. In other words, the lamp head430of the lighting apparatus400includes a plurality of flexible light modules that can be separately and independently installed in a lamp head housing. Due at least in part to the advantages discussed above, the LED lamp head430allows for flexible installation and maintenance and better performance.

One of the broader forms of the present disclosure involves a light module. The light module includes: an array of light illuminating devices disposed on a substrate, wherein each of the light illuminating devices in the array includes a semiconductor photonic device covered by a lens; a metal cover having a plurality of openings, wherein each of the light illuminating devices is disposed within a respective one of the openings; and a heat sink thermally coupled to the substrate.

In some embodiments, the substrate includes a thermally conductive pad; the photonic device includes a light-emitting diode (LED); and the lens includes a secondary lens.

In some embodiments, the secondary lens is reconfigurable.

In some embodiments, the light module is waterproof.

In some embodiments, the light module includes: a waterproof gasket disposed between the substrate and the heat sink; and one or more waterproof connectors coupled to the metal cover.

In some embodiments, the openings of the metal cover are configured as light reflectors for their respective semiconductor photonic devices.

In some embodiments, the heat sink includes a plurality of fins that each contain a respective recess; and the recesses are approximately aligned.

In some embodiments, each fin has a plurality of protruding branch members.

In some embodiments, a plurality of the light modules is operable to be installed within a housing for a cobra head light.

Another one of the broader forms of the present disclosure involves a lighting instrument. The lighting instrument includes: a street light housing; and a plurality of lighting modules and power supply disposed within the street light housing, wherein each of the lighting modules includes: a thermally conductive substrate; a plurality of light-emitting diode (LED) devices located on the substrate; a metal cover disposed over the substrate, wherein the metal cover includes a plurality of openings that are each aligned with a respective one of the LED devices; and a thermal dissipation structure coupled to the substrate.

In some embodiments, the LED devices each include an LED covered by a reconfigurable secondary lens.

In some embodiments, each lighting module includes one or more waterproof components.

In some embodiments, the waterproof components include a waterproof connector and a waterproof gasket.

In some embodiments, each lighting module is secured to the housing through a screw-free mechanism.

In some embodiments, each opening of the metal cover is defined by reflective sidewalls surrounding the respective LED device.

In some embodiments, the thermal dissipation structure includes a board and a plurality of members protruding from the board, and wherein the members contain respective recesses that are substantially aligned with one another.

In some embodiments, the members each include a plurality of branches that extend outwardly from the member.

Still another one of the broader forms of the present disclosure involves a street light. The street light includes: a base; a lamp post coupled to the base; a lamp head coupled to the lamp post, wherein the lamp head includes: a housing; a power module; and a plurality of light modules and power supply disposed within the housing, wherein each lighting module includes a plurality of light-emitting diode (LED), a heat sink thermally coupled to the LED, and a thermally conductive cover having a plurality of openings each aligned with a respective one of the LED.

In some embodiments, each light module includes a plurality of reconfigurable secondary lenses that each cover a respective one of the LED; and each opening of the cover is defined by sidewalls that reflect light emitted by the respective LED.

In some embodiments, each of the light modules is independently waterproof.

In some embodiments, the heat sink includes a plurality of fins having recesses therein, and wherein the recesses are approximately aligned with one another.