Phosphor tape article
A phosphor tape article includes a phosphor layer having a phosphor and a polymeric binder material, a pressure sensitive adhesive layer disposed adjacent the phosphor layer such that light transmitted through the pressure sensitive adhesive layer is received by the phosphor layer, and a release liner disposed on the pressure sensitive adhesive layer. The pressure sensitive adhesive layer is disposed between the release liner and the phosphor layer. The phosphor is suitable for excitation by UV or blue LED light, and the phosphor emission has a characteristic decay rate of less than 1 second. Light emitting devices including pieces of phosphor tape, and methods of making such devices, are also disclosed.
1. A phosphor tape article, comprising:
a phosphor layer comprising a phosphor and a polymeric binder material, the phosphor having a decay rate of less than 1 second;
a pressure sensitive adhesive layer disposed adjacent the phosphor layer, such that light transmitted through the pressure sensitive adhesive layer is received by the phosphor layer; and
a release liner disposed on the pressure sensitive adhesive layer, wherein the pressure sensitive adhesive layer is disposed between the release liner and the phosphor layer;
wherein the phosphor tape article is divided into discrete pieces whose size and shape are suitable for covering encapsulated LEDs.
2. An article according to claim 1 , further comprising a hardcoat layer disposed on the phosphor layer, wherein the phosphor layer is disposed between the pressure sensitive adhesive layer and the hardcoat layer.
3. An article according to claim 1 , wherein the pressure sensitive adhesive layer is disposed on the phosphor layer.
4. An article according to claim 1 , wherein the pressure sensitive adhesive layer comprises a structured surface.
5. An article according to claim 1 , wherein the pressure sensitive adhesive layer comprises a pressure sensitive adhesive that builds adhesion over a time interval.
6. An article according to claim 1 , Wherein the pressure sensitive adhesive layer comprises a curing agent.
7. An article according to claim 1 , wherein the phosphor layer has a haze value in a range from 50% to 100%.
8. An article according to claim 1 , wherein the pressure sensitive adhesive layer comprises a silicone polymer.
9. An article according to claim 1 , wherein the pressure sensitive adhesive layer comprises a photocuring agent.
10. A light emitting device, comprising:
an encapsulated LED that includes an ultraviolet or blue light emitting LED die disposed within a transparent encapsulating material; and
a phosphor tape disposed on the transparent encapsulating material, wherein the phosphor tape comprises:
a phosphor layer including a phosphor and a polymeric binder material; and
a pressure sensitive adhesive layer disposed adjacent the phosphor layer, wherein the pressure sensitive layer is disposed between the phosphor layer and the transparent encapsulating material and contacts the transparent encapsulating material.
11. A device according to claim 10 , wherein the pressure sensitive adhesive layer further comprises an ultraviolet or blue light curing agent.
12. A device according to claim 10 , wherein the encapsulating material has a first index of refraction, the pressure sensitive adhesive layer has a second index of refraction, and the phosphor layer polymeric binder material has a third index of refraction, and the first, second and third index of refractions all have a value within 0.1 at a visible wavelength.
13. A device according to claim 10 , wherein the encapsulating material has a first index of refraction, the pressure sensitive adhesive layer has a second index of refraction, and the phosphor layer polymeric binder material has a third index of refraction, and the second index of refraction has a value between the first and third index of refraction.
14. A device according to claim 10 , wherein the pressure sensitive adhesive layer contacts the phosphor layer.
15. A method of making a light emitting device, comprising:
providing a phosphor tape sheet comprising a phosphor layer including a phosphor and a polymeric binder material, and a pressure sensitive adhesive layer adjacent the phosphor layer, the phosphor tape sheet being divided into discrete phosphor tape articles;
providing an encapsulated LED including an LED die disposed within a transparent encapsulating material, the transparent encapsulating material having an encapsulant surface; and
adhering one of the phosphor tape articles to the encapsulant surface.
16. A method according to claim 15 , further comprising disposing a release liner on the pressure sensitive adhesive layer prior to providing a phosphor tape sheet step.
17. A method according to claim 15 , wherein the LED die emits ultraviolet or blue excitation light and the light emitting device emits white light.
18. A method according to claim 15 , further comprising forming a transparent body on the light emitting device to encapsulate at least a portion of the phosphor tape article.
19. A method according to claim 15 , wherein the encapsulated LED includes a plurality of LED dies disposed within the transparent encapsulating material.