Patent Application
20090290362
1. Technical Field
The present invention relates to light emitting diodes, and more specifically to a light emitting diode device.
2. Description of Related Art
Presently, LEDs (light emitting diode) are preferred for use in non-emissive display devices rather than CCFLs (cold cathode fluorescent lamp) due to their high brightness, long lifespan, and wide color range.
Referring to
However, the LED chip 21 is preferred to be more powerful while maintaining a smaller size. Hot spots form between each of the LED chips 21 and the substrate 22, and heat generated thereat needs to be transferred to other areas of the substrate 22 and further dissipated to the surrounding environment. The substrate 22 has low heat transfer efficiency due to its flat shape restriction and simplex material restriction. Therefore, the heat in the hot spots can not be efficiently dissipated and the hot spots remain.
It is thus desired to provide a LED device which can overcome the described limitations.
A light emitting diode device is provided. According to an exemplary embodiment, the light emitting diode device includes a base, a plurality of light emitting diode chips, a plurality of encapsulation materials and a heat dissipation substrate. The light emitting diode chips are mounted on a top surface of the base. The encapsulation materials are provided on the top surface of the base and encapsulate the light emitting diode chips therein. The heat dissipation substrate is fixedly attached to a bottom surface of the base. The heat dissipation substrate is of a porous material and defines a plurality of pores therein. The pores communicate with each other.
Other advantages and novel features of the present invention will become more apparent from the following detailed description of embodiment when taken in conjunction with the accompanying drawings.
Reference will now be made to the drawings to describe the various present embodiments in detail.
Referring to
The base 321 provides high thermal conductivity. In this embodiment, the base 321 is a metal such as aluminum, copper or other metal. The base 321 defines a plurality of receiving recesses 33 therein. The receiving recesses 33 are concave below a top surface of the base 321 towards a bottom surface of the base 321, being bowl-shaped, and including a bottom face 331 parallel to the top surface of the base 321 and an annular side face 332 extending upwardly and outwardly from the bottom face 331 to the top surface of the base 321. The LED chips 31 are received in the receiving recesses 33 of the base 321, respectively. Each of the LED chips 31 is electrically connected to the base 321 via a gold wire 35. The base 321 defines a plurality of engaging recesses 36 on the bottom surface thereof. The engaging recesses 36 are concaved inwardly from the bottom surface of the base 321 towards the top surface of the base 321. Each of the engaging recesses 36 is bowl-shaped, and has a same shape as the receiving recess 33. Each engaging recess 36 aligns with a corresponding receiving recess 33 and is located directly thereunder. The receiving recesses 33 align with the engaging recesses 36 along a vertical axis of the base 321, respectively.
A top surface of the heat dissipation substrate 323 is fixed to the bottom surface of the base 321. A plurality of protrusions 37 protrude upwardly from the top surface of the heat dissipation substrate 323. The protrusions 37 correspond to the engaging recesses 36 of the bottom surface of the base 321, respectively. Each of the protrusions 37 has a shape and a size substantially equal to those of each of the engaging recesses 36. The protrusions 37 of the heat dissipation substrate 323 are received in the engaging recesses 36 of the base 321, respectively. The heat dissipation substrate 323 is of a porous material having a high thermal conductivity, and defines a plurality of pores therein, wherein the pores communicate with each other. In this embodiment, the heat dissipation substrate 323 is of a metallic foam material, and the heat dissipation substrate 323 and the base 321 are thermally connected together through each protrusion 37 engaging in a corresponding engaging recess 36. A thickness of a flat portion of the heat dissipation substrate 323 on which the protrusion 37 are provided is about 2 mm (millimeter).
The encapsulation material 34 utilizes light-permeable material, such as glass, epoxy, resin, or other. The encapsulation material 34 is filled in a receiving recess 36 for encapsulating the corresponding LED chip 31 therein.
During operation, the LED chips 31 generate heat. Since the LED chips 31 are thermally connected with the base 321, the heat generated by the LED chips 31 is firstly gathered in contact areas between the LED chips 31 and the base 321 and then further conducted to other areas of the base 321 along a horizontal axis thereof and conducted to the heat dissipation substrate 323 along the vertical axis of the base 321, simultaneously. Since the engaging recesses 36 are located under the LED chips 31 and the protrusions 37 are filled in the engaging recesses 36, the heat is quickly conducted to the heat dissipation substrate 323 through the protrusions 37 due to the large contact area between the base 321 and the heat dissipation substrate 323, which improves the heat conduction of the base 321 along the vertical axis thereof and further improves the heat conducting efficiency between the base 321 and the heat dissipation substrate 323. For the large quantities of pores defined in the heat dissipation substrate 323, a total heat dissipation area of the heat dissipation substrate 323 is greatly increased and the heat can be further quickly dissipated to a surrounding environment by the heat dissipation substrate 323, thereby enhancing heat dissipation effectiveness of the LED device 30.
Alternatively, a heat sink may additionally be attached to the bottom surface of the heat dissipation substrate 323, further increasing the heat dissipation effectiveness of the LED device 30. The heat dissipation substrate 323 can be other porous material, such as sintered metal powder, with a high thermal conductivity. If the base 321 is aluminum, the heat dissipation substrate 323 can be a porous anodic oxidation film formed on the bottom surface of the metal base 321.
It is to be understood that 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 function of the embodiments, the disclosure is illustrative only, and changes may be made in detail, 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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200810067417.4 | May 2008 | CN | national |
