Toshiba Lighting and Sharp's new Led Bulb internal structure reveals (1)
Toshiba and Sharp's new LED bulbs are revealed (2): the radiator structure is different
The internal structure of the new LED Bulb is revealed (3): the size of the power supply circuit is significantly different
The internal structure of the new LED bulb is revealed (4): changing the heat dissipation method to achieve low cost
The internal structure of the new LED bulb is revealed (5): improving the heat dissipation of the LED package
Radiator connection construction is different
The hemispherical portion of the diffused LED light is referred to as a "spherical shade." The Toshiba Illuminated Spherical Shade is made of polycarbonate and is fixed to four locations above the heat sink with an adhesive. The spherical lampshade of a conventional light bulb is generally made of glass. This is because the Led Light is not easily heated, so resin can be used. Moreover, after the resin is used, it is not easily broken when the bulb is dropped, and the safety is thereby improved.
The LED substrate is arranged under the spherical lampshade. Among Toshiba Lighting's products, 6.9W (white, total luminous flux 565lm) rated power consumption, the number of LED packages on the LED substrate is 7 (Figure 3) * 5.
Figure 3: The back side of the upper LED substrate of the Toshiba Illumination LED Bulb is in contact with the upper surface of the heat sink (housing) and is directly fixed with 2 screws.
Toshiba's LED substrate is mounted with a connector that connects to the power circuit. The connector is a product that does not need to be soldered, and it is estimated that the ease of assembly is prioritized. Incidentally, Toshiba's LED bulbs are assembled at factories in Japan.
The LED substrate is fixed by 2 screws, and the upper surface of the heat sink can be seen after the substrate is removed. This part is planarized by machining, and the LED substrate can be screwed to the surface of the substrate to obtain thermal conductivity.
The spherical lampshade of Sharp's LED bulbs is made of glass*6. 7.5W (daylight, total luminous flux 560lm) The LED substrate of the rated power consumption is equipped with 6 LED packages (Fig. 4). The wiring between the power circuit backplanes is soldered.
Figure 4: The upper LED substrate of the Sharp LED bulb is attached to the metal plate with 3 screws, coated with heat transfer oil. In addition, the wiring of the power supply circuit board is soldered.
The LED substrate is fixed to the metal plate by 3 screws, and a thermal grease (Grease) is applied between the two. The fixed LED substrate is not a heat sink made of aluminum alloy casting, but an additional metal plate. Although the material is aluminum alloy, there are no mechanical traces on the surface. Fixing the LED substrate with such a metal plate may not be sufficient for the bonding performance of the two, so it is necessary to use a thermal grease.
The metal plate is fixed to the heat sink with three screws (not the screws that fix the LED substrate). It can be seen that the metal plate is removed and the inside of the heat sink is filled with black resin (Fig. 5)*7. It is estimated that these resins are filler materials that promote heat conduction, but these resins are not in contact with the back surface of the metal plate, so it is presumed that the main purpose is to conduct heat to the heat sink circuit board instead of the heat generated by the LED package.
Figure 5: The internal metal plate of the Sharp LED bulb is attached to the heat sink (outer casing) with 3 screws. The inside of the heat sink is filled with filler material, but it is not in contact with the back surface of the metal plate, and heat can only be conducted through the contact portion of the metal plate and the heat sink. In addition, an O-ring is arranged between the two to ensure airtightness.
The contact portion between the heat sink and the metal plate is annular, and the area is not large. The contact portion on the back side of the metal plate has a full-circle flange, which is not only easy to position when assembled, but also slightly enlarges the contact area. In addition, the outer edge of the metal plate is exposed to the outside of the bulb, which becomes an embellishment on the design of the bulb.
The use of an O-ring disposed around the contact portion of the metal plate and the heat sink is not known. If it is to maintain airtightness, the effect of the ring should be to prevent leakage of the material after filling the liquid resin and to prevent water from entering from the outside. It is also conceivable to promote the transfer of heat from the metal plate to the heat sink. (To be continued, "Nikkei Manufacturing" dismantling group)
*5: Toshiba Lighting 4.1W type (white, total luminous flux 340lm) LED bulb is equipped with 4 LED packages.
*6: The inner surface of the glass is coated with a astigmatic coating, which can convert the directional LED light into a uniform surface illuminating.
*7: In terms of Sharp LED bulbs, the disassembled product (product with rated power consumption of 7.5W) weighs 158g and 4.1W weighs 118g. It can be speculated that there may be differences between the components and the internal structure.
Toshiba Lighting and Sharp's new LED bulb internal structure reveals (1)
Toshiba and Sharp's new LED bulbs are revealed (2): the radiator structure is different
The internal structure of the new LED bulb is revealed (3): the size of the power supply circuit is significantly different
The internal structure of the new LED bulb is revealed (4): changing the heat dissipation method to achieve low cost
The internal structure of the new LED bulb is revealed (5): improving the heat dissipation of the LED package
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