LED module having heat dissipation structure and optimal light distribution

[0001] 1. Field of the Invention

[0002] The present invention relates to an LED module, especially to an LED module having a heat dissipation structure and optimal light distribution.

[0003] 2. Description of the Related Art

[0004] Because of risk of energy shortage and improved public awareness, governments and environmental organizations are making efforts to promote energy conservation through improved light sources. Current solutions include low-energy, fluorescent bulbs, but these are bulky and contain mercury so causing possible health problems if broken or when incorrectly disposed of.

[0005] Therefore, light emitting diodes (hereafter LED) are small and efficient. Furthermore developing LED technology is constantly enhancing illumination of LEDs and reducing production costs so LEDs are beginning to replace other light sources.

[0006] However, an LED module for use in an LED lamp usually provides a small and uneven illuminating area since each LED emits highly directional light. If the LED module is disposed on a ceiling, a light gradient decreases from a center to a periphery more obviously than a fluorescent light.

[0007] Besides, the LED module requires many simultaneously illuminated LEDs that generate heat. Conventionally, the heat is dissipated by multiple metallic fins mounted on the LED module to increase a surface area of the LED module and improve heat conduction. However, use for extended periods increases air temperature around the fins and lowers a heat dissipating efficiency of the LED module.

[0008] To overcome the shortcomings, the present invention provides an LED module having a heat dissipation structure and optimal light distribution in order to mitigate or obviate the aforementioned problems.

[0009] The main objective of the present invention is to provide an LED module having a heat dissipation structure and optimal light distribution.

[0010] The LED module comprises a heat dissipating bracket, a substrate, multiple LED assemblies and two rotatable mounting assemblies. The heat dissipating bracket has a top panel, a bottom panel and multiple flues. Each flue connects a corresponding top hole of the top panel and a bottom hole of the bottom panel. The substrate is mounted on the bottom panel and has multiple independent through holes respectively corresponding to the flues. The LED assemblies are respectively mounted on the substrate between two adjacent through holes. The rotatable mounting assemblies are respectively connected to two ends of the heat dissipating bracket, wherein the heat dissipating bracket is adapted to change an illuminating direction of the LED assemblies by rotating with the rotatable mounting assemblies. With the heat dissipating bracket and the rotatable mounting assemblies, the LED module obtains good heat-dissipating efficiency and optimal light distribution.

[0011] Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0024] With reference to FIG. 1, an LED module in accordance with the present invention comprises a heat dissipating bracket (10), a substrate (20), multiple LED assemblies (30) and two rotatable mounting assemblies (40).

[0025] With further reference to FIG. 2, the heat dissipating bracket (10) has two opposite ends, a top panel (11), a bottom panel (12) and multiple flues (13). The top panel has multiple independent top holes (110) formed through the top panel (11). The bottom panel (12) has a front surface and multiple independent bottom holes (120) formed through the bottom panel (12) respectively corresponding to the top holes (110). The flues (13) are mounted between the top and the bottom panels (11, 12) and connect corresponding top and bottom holes (110, 120).

[0026] The substrate (20) is mounted on the front surface of the bottom panel (12) and has multiple independent through holes (200). The through holes (200) of the substrate (20) are formed through the substrate (20) and correspond to the flues (13). The substrate (20) may have multiple metal wires forming a circuit and may be bound to the front surface of the bottom panel (12) with heat conductive adhesive.

[0027] With further reference to FIG. 3, each LED assembly (30) is mounted on the substrate (10) between two adjacent through holes (200). In a first embodiment of the present invention, the LED assembly (30) comprises an LED unit (31), a sleeve (32), a lens unit (33), a first waterproof washer (34) and a second waterproof washer (35). The LED unit (31) may be soldered on the substrate (10) by surface mount technology. The sleeve (32) is mounted around the LED unit (31). The lens unit (33) is received in the sleeve (32) and mounted on the LED unit (31). The first waterproof washer (34) is disposed between the sleeve (32) and the substrate (10). The second waterproof washer (35) is disposed between the lens unit (33) and the sleeve (32). The LED assemblies (30) are waterproofed by the first and the second waterproof washers (34, 35). When the LED units (31) are alight and air around the bottom panel (12) is heated so the temperature at the bottom holes (120) of the bottom panel (12) will be higher than at the top holes (110) of the top panel (11) and air density at the bottom holes (120) of the bottom panel (12) will be lowered. Since the flues (13) connect the bottom holes (120) and top holes (110), air currents are formed to move air through the flues (13) from the bottom holes (120) to the top holes (110). Such directional convection will reach a thermal equilibrium at a lower temperature when compared to non-directional convection of conventional LED modules. Therefore heat-dissipating efficiency is enhanced.

[0028] The rotatable mounting assemblies (40) are respectively connected to the ends of the heat dissipating bracket (10), wherein the heat dissipating bracket (10) is adapted to change an illuminating direction of the LED assemblies (30) by rotating with the rotatable mounting assemblies (40). Each has a fixed member (41) and a rotating member (42). The fixed member (41) is adapted to be mounted on a mount of a casing of an LED lamp. The rotating member (42) is rotatably attached with the fixed member (41) and connected to a corresponding end of the heat dissipating bracket (10), wherein the heat dissipating bracket (10) rotates relative to the fixed member (41) via the rotating member (42). In a first embodiment of the rotatable mounting assembly (40), the fixed member (41) and the rotating member (42) are cylinders. The fixed member (41) is coaxial with the rotating member (42), protrudes from a surface of the rotating member (42) and has a diameter smaller than a diameter of the rotating member (42).

[0029] With further reference to FIG. 6, in a second embodiment of the rotatable mounting assembly (40), the fixed member (41a) is ring-shaped and mounted around the rotating member (42a).

[0030] With further reference to FIG. 7, in a third embodiment of the rotatable mounting assembly (40), the fixed member (41b) is L-shaped and has a body and a mounting tab. The body is to be attached with the rotating member (42b). The mounting tab is formed on and protrudes transversely from the body and is to be mounted on a mount of a housing of an LED lamp.

[0031] With further reference to FIG. 8, the rotating member (42c) has an end and an adjusting panel (420). The adjusting panel (420) is mounted on the end of the rotating member (42c) and has a curved slot (421). The fixed member (41c) has a surface and a protrusion (410). The protrusion (410) is formed on and protrudes from the surface of the fixed member (41c) and mounted slidably in the curved slot (421) of the adjusting panel (420).

[0032] With further reference to FIGS. 4 and 5, in a second embodiment of the LED module, the LED module further comprises a cover (50) mounted on the substrate (20) and each LED assembly (30) has an LED unit (31) and a lens (33a). The LED unit (3.1) is soldered on the substrate (20) through the cover (50). The lens unit (33a) is mounted on the LED unit (31) and has a bottom. The bottom of the lens unit (33a) may be connected to the substrate (20) and the cover (50) using epoxy resin.

[0033] With reference to FIG. 9, when applied to an LED lamp, multiple LED modules (1) of the present invention are arranged on an emission side of a casing (2) of the LED lamp side by side. Each LED module (1) is attached with the casing (2) by fixing the fixed members (41) of the rotatable assemblies (40) to corresponding mounts of the casing (2). Since the rotating members (42) are rotatably attached with the fixed members (41), the heat dissipating bracket (10) can rotate relative to the fixed members (41) to change an illuminating direction of the LED assemblies (30). As long as each LED module (1) is adjusted in appropriate illuminating directions, the LED lamp can provide a wider illuminating range and an even illumination.

[0034] Besides, the LED modules (1) are not limited to be arranged side by side, any arrangement is possible to meet a design requirement. With further reference to FIG. 10, a group of LED modules (1) may be disposed perpendicular to another group of LED modules (1).

[0035] With further reference to FIG. 11, the casing (2) of the LED lamp may provide a central plane (200) and two side planes (201) for arranging multiple LED modules (1), wherein the side planes (201) are extended obliquely from two opposite sides of the central plane (200). Furthermore, the lens unit (33) has a diffractor that evenly diverges a point light source of an LED. Hence each of the LED assemblies (30) provides a uniform light source having a particular illuminating range. To meet a required light distribution, the LED modules (1) with different illuminating directions may cooperate with different lens unit (33) providing diffraction, refraction or dispersion.

[0036] With further reference to FIG. 12, the present invention may be practiced in a lighting control system. The lighting control system may comprise multiple LED modules (1), a power supply (6), multiple constant current drivers (7) and a micro control unit (8). The power supply (6) may be an AC/DC adapter that converts AC utility power to DC power or may be a solar cell system that provides DC power. Each constant current driver (7) is connected to an LED module (1), has a PWM (pulse width modulation) capability and may be a nonlinear buck DC-DC converter having a PWM brightness control pin. The micro control unit (8) is connected to the constant current drivers (7) to set an operation current for each LED module (1) via the constant current drivers (7). The micro control unit (8) first sets a duty cycle of a square waveform signal and sends the square waveform signal to the PWM brightness control pins of the constant current drivers (7) to set the operation current of each LED module (1). For example, when a maximum operation current value is set at 700 mA by voltage division, the constant current driver (7) can output a maximum operation current of 700 mA when a high voltage level signal of 5 volts is supplied to the PWM brightness control pin. When the PWM brightness control pin receives a square waveform signal of a duty cycle of 90%, the constant current drivers (7) then adjusts the operation current to 630 mA. When the PWM brightness control pin received a square waveform signal of a duty cycle of 80%, the constant current drivers (7) then adjusts the operation current to 560 mA; 70% to 490 mA, and so on. Therefore, by setting the square waveform signal of different duty cycle and supplying the signal to the PWM brightness control pin of each constant current driver (7), the micro control unit (8) can accurately and efficiently set the operation current of, each LED module (1) to suitable values. Thereby the illumination distribution can be adjusted as required.

[0037] Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.