Nthdegree Technologies Worldwide Inc.

Reuben Rettke

Mark David Lowenthal

William Johnstone Ray

Alexander Ray

Bradley Steven Oraw

Jeffrey Baldridge

LED dies are suspended in an ink and printed on a first support substrate to form a light emitting layer having a light emitting surface emitting primary light, such as blue light. A mixture of a transparent binder, phosphor powder, and transparent glass beads is formed as an ink and printed over the light emitting surface. The mixture forms a wavelength conversion layer when cured. The beads are preferably sized so that the tops of the beads protrude completely through the conversion layer. Some of the primary light passes through the beads with virtually no attenuation or backscattering, and some of the primary light is converted by the phosphor to secondary light. The combination of the secondary light and the primary light passing though the beads may form white light. The overall color is highly controllable by controlling the percentage weight of the beads.

Phosphor layer containing transparent features over blue LED

In a method for forming a phosphor-converted LED, an array of vertical LEDs is printed over a conductive surface of a substrate such that a bottom electrode of the LEDs ohmically contacts the conductive surface. A dielectric layer then formed over the conductive surface. An electrically conductive phosphor layer is deposited over the dielectric layer and the LEDs to ohmically contact the top surface of the LEDs and connect the LEDs in parallel. The conductive phosphor layer is formed by phosphor particles intermixed with a transparent conductor material. One or more metal contacts over the conductive phosphor layer conduct current through the conductive phosphor layer and the LEDs to illuminate the LEDs. A portion of light generated by the LED leaks through the conductive phosphor layer, and the combination of the LED light and phosphor light creates a composite light.

Layered conductive phosphor electrode for vertical LED and method for forming same

A flexible light sheet lamp includes a thin substrate and an array of printed microscopic vertical LEDs (VLEDs) sandwiched between a transparent first conductor layer and a transparent second conductor layer. The light sheet has a light exit surface. The VLEDs have one surface, facing the light exit surface of the light sheet, covered with a reflective metal. A phosphor layer is provided such that the semi-transparent VLED layer is between the phosphor layer and the light exit surface. A reflector layer is provided such that the phosphor layer is between the reflector layer and the VLED layer. The substrate may form the light exit surface or the light exit surface may be the opposite side of the light sheet. Some VLED light passing through the phosphor layer is reflected by the reflector layer and re-enters the phosphor layer. Therefore, less phosphor is needed to achieve the desired conversion ratio.

Transparent LED layer between phosphor layer and light exit surface of lamp

Many thousands of micro-LEDs (e.g., 25 microns per side) are deposited on a substrate. Some of the LEDs are formed to emit a peak wavelength of 450 nm (blue), and some are formed to emit a peak wavelength of 490 nm (cyan). A YAG (yellow) phosphor is then deposited on the LEDs, or a remote YAG layer is used. YAG phosphor is most efficiently excited at 450 nm and has a very weak emission at 490 nm. The two types of LEDs are GaN based and can be driven at the same current. The ratio of the two types of LEDs is controlled to achieve the desired overall color emission of the LED lamp. The blue LEDs optimally excite the YAG phosphor to produce white light having blue and yellow components, and the cyan LEDs broaden the emission spectrum to increase the CRI of the lamp while improving luminous efficiency. Other embodiments are described.

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Phoenix, AZ, United States of America

Reuben Rettke