Solid state lamp using light emitting strips
In one embodiment, an LED lamp has a generally bulb shape. The LEDs are low power types and are encapsulated in thin, narrow, flexible strips. The LEDs are connected in series in the strips to drop a desired voltage. The strips are affixed to the outer surface of a bulb form to provide structure to the lamp. The strips are connected in parallel to a power supply, which may be housed in the lamp. Since many low power LEDs are used and are spread out over a large surface area, there is no need for a large metal heat sink. Further, the light emission is similar to that of an incandescent bulb. In other embodiment, there is no bulb form and the strips are bendable to have a variety of shapes. In another embodiment, a light sheet is bent to provide 360 degrees of light emission. Many other embodiments are described.
1. A solid-state lamp comprising:
a plurality of free-standing strips spaced apart from each other, each of the strips extending along a length from a first end to a second end and comprising a plurality of spaced-apart unpackaged light-emitting diode (LED) dies arranged between the first end and the second end, the LED dies being encapsulated on the strips by an encapsulant comprising a phosphor and a binder and the LED dies being operatively connected and powered from the first end of the strip;
a base having a plurality of spaced-apart connection locations each configured to receive at least one of the free-standing strips at its corresponding first end;
an electrical connector configured to connect the solid-state lamp to an external source of power; and
an outer shell forming a hollow,
wherein the free-standing strips extend from the base into the hollow.
2. The solid-state lamp of claim 1 , wherein the strips extend along their lengths non-perpendicular to an axis of rotation of the lamp.
3. The solid-state lamp of claim 1 , wherein each strip has at least two of the LED dies arranged along the length of the strip in one or more columns of LED dies.
4. The solid-state lamp of claim 3 , wherein each of the one or more columns of LED dies is separately encapsulated by an encapsulant comprising a phosphor and a binder.
5. The solid-state lamp of claim 3 , wherein the one or more columns of LED dies are arranged on only one side of the corresponding strip.
6. The solid-state lamp of claim 5 , wherein the one or more columns of LED dies are arranged facing the outer shell.
7. The solid-state lamp of claim 3 , wherein one or more grooves extend along a portion of the length of each of the strips and the LED dies are arranged in the one or more grooves.
8. The solid-state lamp of claim 3 , wherein each strip has only a single column of LED dies.
9. The solid-state lamp of claim 3 , wherein each strip comprises multiple of the columns of LED dies.
10. The solid-state lamp of claim 9 , wherein different columns of LED dies of each strip have different spectral power distributions.
11. The solid-state lamp of claim 9 , wherein each of the columns of LED dies of each strip has a corresponding electrical connection at the first end separate from electrical connections at the first end corresponding to the other columns of LED dies of the strip.
12. The solid-state lamp of claim 3 , wherein different columns of LED dies have different spectral power distributions.
13. The solid-state lamp of claim 3 , wherein different columns of LED dies are separately powered.
14. The solid-state lamp of claim 3 , further comprising a controller configured to control amounts of light output by different columns based on an input signal.
15. The solid-state lamp of claim 3 , wherein each of the strips comprises metal conductors electrically connecting the LED dies in the corresponding columns.
16. The solid-state lamp of claim 15 , wherein the LED dies in each of the columns of LED dies are electrically connected in series.
17. The solid-state lamp of claim 15 , wherein each strip further comprises at least one trace, the at least one trace providing power from the first end of the strip to one or more of the columns of LED dies.
18. The solid-state lamp of claim 15 , wherein each strip comprises at least one lead, the at least one lead receiving power at the first end of the strip for one or more of the columns of LED dies.
19. The solid-state lamp of claim 1 , wherein each strip comprises a corresponding metal portion.
20. The solid-state lamp of claim 19 , wherein the metal portion of each of the strips comprises a backplane providing a restorative force to the shape of the strip.
21. The solid-state lamp of claim 20 , wherein each of the backplanes is configured to receive heat from the LED dies of the corresponding strip during operation of the solid-state lamp.
22. The solid-state lamp of claim 19 , wherein the metal portion comprises copper or aluminum.
23. The solid-state lamp of claim 1 , wherein the outer shell comprises a light-transmissive material.
24. The solid-state lamp of claim 1 , wherein the strips are straight strips.
25. The solid-state lamp of claim 1 , wherein the strips are curvilinear.
26. The solid-state lamp of claim 1 , wherein the strips are non-parallel to each other.
27. The solid-state lamp of claim 1 , wherein each strip has a uniform width along its length.
28. The solid-state lamp of claim 1 , wherein all strips have the same shape.
29. The solid-state lamp of claim 1 , wherein the LED dies are arranged to emit light from only one side of the strips.
30. The solid-state lamp of claim 1 , wherein the strips extend along their lengths non-parallel to an axis of rotation of the lamp.