Micro display panels with integrated micro-reflectors
A display panel with integrated micro-reflectors. The display panel also includes an array of pixel light sources (e.g., micro-LEDs) electrically coupled to corresponding pixel driver circuits (e.g., FETs). The micro-LEDs produce light and the micro-reflectors reduce the divergence of the light produced by the micro-LEDs. Different designs are possible. The micro-reflectors can have different shapes, include the shape of their sidewalls and the shape of their plan cross-section. The array schemes can also vary, including the number of LEDs per micro-reflector. Different fabrication approaches are also possible. In one approach, a support structure is integrated between micro-LEDs. The sides of the support structure are reflective and serve as the reflective sidewalls of the micro-reflector. Alternately, the LED mesa itself can serve as the support structure.
1. A display panel comprising:
a substrate;
an array of micro-LEDs that produce light;
an array of pixel driver circuits that is electrically coupled to the array of micro-LEDs, wherein the pixel driver circuits drive corresponding micro-LEDs and each micro-LED is individually controllable; and
an array of micro-reflectors aligned to the micro-LEDs to reduce a divergence of the light produced by the micro-LEDs, wherein the micro-reflectors are reflective cups, the micro-LEDs positioned at a base of the reflective cups;
wherein the arrays of pixel driver circuits, micro-LEDs and micro-reflectors are all integrated on the substrate.
2. The display panel of claim 1 , wherein the array of micro-reflectors includes one micro-reflector per micro-LED, each micro-reflector reducing the divergence of the light produced by the corresponding micro-LED.
3. The display panel of claim 1 , wherein the array of micro-reflectors includes one micro-reflector per group of two or more micro-LEDs, each micro-reflector reducing the divergence of the light produced by the micro-LEDs in the corresponding group.
4. The display panel of claim 3 , wherein the array of micro-LEDs includes different color micro-LEDs, and each group contains a same number of each color micro-LED.
5. The display panel of claim 1 , wherein the reflective cups comprise a reflective coating applied to sidewalls of the micro-LEDs.
6. The display panel of claim 1 , wherein the reflective cups comprise support structures integrated on the substrate between the micro-LEDs, the support structures having reflective surfaces.
7. The display panel of claim 1 , wherein the reflective cups have straight sidewalls.
8. The display panel of claim 1 , wherein the reflective cups have curved sidewalls.
9. The display panel of claim 1 , wherein the reflective cups have a plan cross-section that is one of circular, polygonal or irregular.
10. The display panel of claim 1 , wherein the reflective cups are taller than the micro-LEDs, and a height of the reflective cups is at least twice a lateral size of the micro-LEDs.
11. The display panel of claim 1 , wherein the reflective cups have sidewalls with a sidewall angle that is steeper than 45 degrees.
12. The display panel of claim 1 , wherein the micro-reflectors reduce a maximum divergence angle of the light produced by the micro-LEDs by at least 60%.
13. The display panel of claim 1 , wherein the micro-reflectors increase an on-axis brightness of the light produced by the micro-LEDs by at least 10×.
14. The display panel of claim 1 , further comprising:
an array of microlenses aligned to the micro-LEDs and micro-reflectors, the microlenses positioned above the micro-reflectors to further reduce the divergence of the light produced by the micro-LEDs.
15. The display panel of claim 1 , further comprising:
an array of micro-caps positioned inside the micro-reflectors, the micro-LEDs immersed in the micro-caps, the micro-caps increasing a light extraction efficiency of the micro-LEDs without adversely affecting the reduction of divergence achieved by the micro-reflectors.
16. The display panel of claim 14 , further comprising:
a spacer between the micro-LEDs and the microlenses.
17. A display panel comprising:
a substrate;
an array of micro-LEDs that produce light;
an array of pixel driver circuits that is electrically coupled to the array of micro-LEDs, wherein the pixel driver circuits drive corresponding micro-LEDs and each micro-LED is individually controllable; and
an array of micro-reflectors aligned to the micro-LEDs to reduce a divergence of the light produced by the micro-LEDs, wherein the micro-reflectors are reflective cups coated with a reflective metal layer, the micro-LEDs are positioned at a base of the reflective cups, and the reflective metal layer also makes electrical contact with one electrode of the micro-LEDs;
wherein the arrays of pixel driver circuits, micro-LEDs and micro-reflectors are all integrated on the substrate.
18. The display panel of claim 17 , wherein the reflective metal layer is electrically connected to a common electrode of the micro-LEDs through a transparent conducting layer.
19. The display panel of claim 17 , wherein the reflective metal layer is electrically connected to a common electrode of the micro-LEDs by contact fingers.
20. A display panel comprising:
a substrate;
an array of micro-LEDs that produce light;
an array of pixel driver circuits that is electrically coupled to the array of micro-LEDs, wherein the pixel driver circuits drive corresponding micro-LEDs and each micro-LED is individually controllable; and
an array of micro-reflectors aligned to the micro-LEDs to reduce a divergence of the light produced by the micro-LEDs, wherein the micro-reflectors are reflective cups coated with a reflective metal layer, the micro-LEDs are positioned at a base of the reflective cups, and the reflective metal layers of adjacent reflective cups are electrically connected;
wherein the arrays of pixel driver circuits, micro-LEDs and micro-reflectors are all integrated on the substrate.