1. An LED lamp comprising: a heat sink comprising a core, a plurality of branches fixed on the core and extending outwards from an outer circumference of the core and a plurality of fins formed on two opposite sides of each branch, each branch defining an inclined surface on a top thereof, a distance between the inclined surface and the core gradually increasing from a first end of the core to a second end thereof which is opposite to the first end of the core, wherein the fins are decreased in height along a direction outwards from the core and have top surfaces thereof coplanar with the inclined surface; and an LED module mounted on the inclined surface of the each branch of the heat sink.
2. The LED lamp as claimed in claim 1, wherein the core is prism-shaped and has a plurality of sidewalls on the outer circumference thereof, the branches respectively extending perpendicularly and outwardly from the sidewalls of the core.
3. The LED lamp as claimed in claim 1, wherein the fins are increased in length along the direction outwards from the core and have bottom surfaces coplanar with a bottom surface of the core and bottom surfaces of the branches.
4. The LED lamp as claimed in claim 3, wherein the fins are perpendicular to the each branch and symmetrical to each other relative to the each branch.
5. The LED lamp as claimed in claim 1, wherein the inclined surface of the each branch is inclined to the core with a same angle.
6. The LED lamp as claimed in claim 1 further comprising a base having a base plate, an engaging flange extending upwards from an outer edge of a top surface of the base plate and a plurality of projecting vanes arranged on a bottom surface of the base plate opposite to the top surface, wherein the heat sink is disposed on the top surface of the base plate opposite to the engaging flange and surrounded by the engaging flange.
7. The LED lamp as claimed in claim 6, wherein the base further comprises a receiving cylinder formed on the bottom surface of the base plate, wherein the receiving cylinder defines a receiving room therein and extends downwardly from a central portion of the bottom surface of the base plate, the projecting vanes extending radially outwardly from an outer circumference of the receiving cylinder.
8. The LED lamp as claimed in claim 7 further comprising a mounting member, wherein the mounting member has a mounting plate engaging with a lower end of the receiving cylinder and a sleeve extending downwardly from the mounting plate.
9. The LED lamp as claimed in claim 6 further comprising a cover, wherein the cover is a frustum in shape and has an annular fixing flange formed at a lower edge thereof, the fixing flange engaging with the engaging flange of the base, the cover enclosing the heat sink and the LED modules therein.
10. An LED lamp comprising: a base having a base plate, an engaging flange extending upwards from an outer edge of a top surface of the base plate and a plurality of projecting vanes formed on a bottom surface of the base plate opposite to the engaging flange; a heat sink placed on the top surface of the base plate and surrounded by the engaging flange and comprising a core, a plurality of branches formed on the core and extending outwards from an outer circumference of the core and a plurality of fins formed on two opposite sides of each branch, each branch defining an inclined surface on a top thereof, a distance between the inclined surface and the core gradually increasing from a first end to a second end of the core, which is opposite to the first end of the core, wherein the fins are decreased in height along a direction outwards from the core and have top surfaces coplanar with the inclined surface; and an LED module having a printed circuit board mounted on the inclined surface of the each branch of the heat sink.
11. The LED lamp as claimed in claim 10, wherein the core is prism-shaped and has six sidewalls on the outer circumference thereof, the branches respectively extending perpendicularly from the sidewalls of the core.
12. The LED lamp as claimed in claim 10, wherein the each branch is a right-angled triangle in profile, and wherein the inclined surface is corresponding to a bevel edge of the triangle and inclined to the core with a same angle.
13. The LED lamp as claimed in claim 12, wherein the fins are increased in length along the direction outwards from the core and have bottom surfaces coplanar with a bottom surface of the core and bottom surfaces of the branches.
14. The LED lamp as claimed in claim 10, wherein the fins are perpendicular to the each branch and symmetrical to each other relative to the each branch.
15. The LED lamp as claimed in claim 10, wherein the base further comprises a receiving cylinder defining a receiving room therein and extending downwardly from a central portion of the bottom surface of the base plate, the projecting vanes extending radially outwardly from an outer circumference of the receiving cylinder.
16. The LED lamp as claimed in claim 15 further comprising a mounting member having a mounting plate engaging with a lower end of the receiving cylinder and a sleeve extending downwardly from the mounting plate.
17. The LED lamp as claimed in claim 15 further comprising a cover which is a frustum in shape and has an annular fixing flange formed at a lower edge thereof, the fixing flange engaging with the engaging flange of the base, the cover enclosing the heat sink and the LED modules therein.
18. The LED lamp as claimed in claim 10 wherein the core defines a hole therein along an axis thereof for facilitating an extension of the electrical wires to be electrically connected to the LED modules.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A perpendicular magnetic recording medium, comprising:
a non-magnetic base, and
a magnetic recording layer on the non-magnetic base, wherein the magnetic recording layer comprises a first magnetic layer, a first exchange coupling control layer, a second magnetic layer, a third magnetic layer, and a fourth magnetic layer, in that order, wherein when the perpendicular magnetic anisotropy constants of the first magnetic layer, second magnetic layer, third magnetic layer, and fourth magnetic layer are Ku1, Ku2, Ku3, and Ku4 respectively, relationships of Ku4>Ku3>Ku2 and Ku1>Ku3>Ku2 are satisfied.
2. The perpendicular magnetic recording medium according to claim 1, wherein a second exchange coupling control layer is provided between the second magnetic layer and third magnetic layer.
3. The perpendicular magnetic recording medium according to claim 1, wherein a second exchange coupling control layer is provided between the third magnetic layer and fourth magnetic layer.
4. The perpendicular magnetic recording medium according to claim 1, wherein a second exchange coupling control layer is provided between the second magnetic layer and third magnetic layer, and a third exchange coupling control layer is provided between the third magnetic layer and fourth magnetic layer.