# US 11,112,652 B2 · Backlight unit and display device including the same technical field

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- Number: US 11,112,652 B2
- Document ID: US11112652B2
- Status: Granted
- Kind: B2
- Application number: 16/702,473
- Filed: 2019-12-03
- Published: 2020-06-11
- Granted: 2021-09-07
- Earliest claimed: 2018-12-11
- Assignees: LG Display Co., Ltd.
- Applicants: LG Display Co., Ltd.
- Inventors: Donghwi Kim; KiSeong Kim; HyeokJoon Yoon; SeungJu Gwon
- Web page: https://patentgrep.com/patent/US11112652B2

## CPC

- G02F 1/133611: {including means for improving the brightness uniformity}
- G02F 1/133603: {with LEDs}
- G02F 1/133605: {including specially adapted reflectors}
- G02F 1/133606: {including a specially adapted diffusing, scattering or light controlling members}
- G02F 1/133607: {the light controlling member including light directing or refracting elements, e.g. prisms or lenses}
- G02F 1/133614: {using photoluminescence, e.g. phosphors illuminated by UV or blue light}
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

In an embodiment, a backlight unit includes a light-emitting device and lower reflector on a substrate. The lower reflector has a hole that accommodates and exposes the light-emitting device. The lower reflector may have a height greater than a height of the light-emitting device. The backlight unit may include a color resin in the holes and on the light-emitting device. The backlight unit may include a light path modulator above the light emitting device and on the color resin. The light path modulator may have a different refractive index than a refractive index of the color resin to reflect the emitted light at a boundary of the light path modulator and the color resin towards the lower reflector.

## Claims

### Claim 1

A backlight unit comprising:
a substrate;
a light-emitting device on the substrate;
a lower reflector on the substrate, the lower reflector with a hole that accommodates and exposes the light-emitting device, the lower reflector having a height greater than a height of the light-emitting device and configured to reflect light emitted from the light-emitting device;
a color resin in the hole and on the light-emitting device, and having a height lower than the height of the lower reflector;
a light path modulator above the light-emitting light emitting device and on the color resin, the light path modulator having a different refractive index than a refractive index of the color resin to reflect the emitted light at a boundary of the light path modulator and the color resin towards the lower reflector;
an adhesive film on the lower reflector and the light path modulator; and
a light-modifying sheet on the adhesive film, the light-modifying sheet including a plurality of light-modifying patterns,
wherein the light path modulator overlaps with at least one of the plurality of light-modifying patterns, and
wherein the light path modulator is located within the hole and surrounded by the color resin, the lower reflector, and the adhesive film.

### Claim 2 (depends on 1)

The backlight unit of claim 1, wherein the color resin includes a plurality of phosphors having at least two different colors.

### Claim 3 (depends on 1)

The backlight unit of claim 1, wherein the color resin has an upper surface that is concave or convex.

### Claim 4 (depends on 1)

The backlight unit of claim 1, wherein the light path modulator comprises air.

### Claim 5 (depends on 1)

The backlight unit of claim 1, further comprising:
a distributed Bragg reflector on the light-emitting device, the distributed Bragg reflector in the hole and between the substrate and the light path modulator.

### Claim 6 (depends on 1)

The backlight unit of claim 1,
wherein the plurality of light-modifying patterns at least partially overlap the light-emitting device, the plurality of light-modifying patterns having one or more layers including a top layer on a surface of the light-modifying sheet facing the substrate, air gaps present between the one or more layers and the adhesive film.

### Claim 7 (depends on 6)

The backlight unit of claim 6, wherein the one or more layers further includes:
a middle layer on a surface of the top layer facing the substrate, the top layer having a size greater than a size of the middle layer.

### Claim 8 (depends on 7)

The backlight unit of claim 7, wherein the one or more layers further includes:
a bottom layer on a surface of the middle layer facing the substrate, the bottom layer having a size less than the size of the middle layer.

### Claim 9 (depends on 6)

The backlight unit of claim 6, further comprising:
a phosphor film on the light-modifying sheet;
a diffusion plate on the phosphor film; and
an optical sheet on the diffusion plate.

### Claim 10 (depends on 1)

The backlight unit of claim 1, wherein a width of the light path modulator has a same size as a width of the hole, and a height of the light path modulator has a size resulting from subtracting a height of the color resin from a height of the hole.

### Claim 11

A backlight unit comprising:
a substrate including a groove having side walls applied with a reflective material and having a first height;
a light-emitting device in the groove and having a second height lower than the first height;
a color resin in the groove and on the light-emitting device, the color resin having a third height lower than the first height;
a light path modulator in the groove and on the color resin, the light path modulator having a refractive index different from a refractive index of the color resin to reflect light emitted from the light-emitting device at a boundary of the light path modulator and the color resin towards the side walls of the grooves;
an adhesive film on the light path modulator; and
a light-modifying sheet on the adhesive film, the light-modifying sheet including a plurality of light-modifying patterns,
wherein the light path modulator overlaps with at least one of the plurality of light-modifying patterns, and
wherein the light path modulator is located within the groove and surrounded by the color resin, the side walls, and the adhesive film.

### Claim 12 (depends on 11)

The backlight unit of claim 11, wherein the color resin includes a plurality of phosphors having at least two different colors.

### Claim 13 (depends on 11)

The backlight unit of claim 11, wherein the color resin has an upper surface that is concave or convex.

### Claim 14 (depends on 11)

The backlight unit of claim 11, wherein the light path modulator comprises air.

### Claim 15 (depends on 11)

The backlight unit of claim 11, further comprising:
a distributed Bragg reflector on the light-emitting device, the distributed Bragg reflector in the groove and between the substrate and the light path modulator.

### Claim 16

A method for manufacturing a backlight unit, the method comprising:
disposing a plurality of light-emitting devices in areas of a substrate;
disposing a lower reflector on the substrate with holes of the lower reflector accommodating and exposing the plurality of light-emitting devices, the holes having a depth greater than a height of the plurality of light-emitting devices;
curing a color resin in the holes, the cured resin having a height lower than the depth;
disposing a light path modulator in the holes and on the color resin, the light path modulator having a different refractive index than that of the color resin;
disposing an adhesive film on the lower reflector and the light path modulator; and
disposing a light-modifying sheet on the adhesive film, the light-modifying sheet including a plurality of light-modifying patterns,
wherein the light path modulator overlaps with at least one of the plurality of light-modifying patterns, and
wherein the light path modulator is located within at least one of the holes and surrounded by the color resin, the lower reflector, and the adhesive film.

### Claim 17 (depends on 16)

The method of claim 16, further comprising:
disposing reflectors on the plurality of light-emitting devices; and
coating the substrate with a reflective material.

### Claim 18 (depends on 16)

The method of claim 16,
wherein the plurality of light-modifying patterns at least partially overlap the plurality of light-emitting devices, the plurality of light-modifying patterns having one or more layers including a top layer on a surface of the light-modifying sheet facing the substrate, air gaps present between the one or more layers and the adhesive film.

### Claim 19 (depends on 18)

The method of claim 18, further comprising:
printing the top layer on the surface of the light-modifying sheet.

### Claim 20 (depends on 19)

The method of claim 19, further comprising:
printing a middle layer of the one or more layers on the top layer, the top layer having an area greater than an area of the middle layer, wherein the light-modifying sheet having the printed top layer and middle layer is reversed before disposing the light-modifying sheet on the adhesive film.

### Claim 21 (depends on 20)

The method of claim 20, further comprising:
printing a bottom layer of the one or more layers on the middle layer, the bottom layer having an area less than the area of the middle layer.

### Claim 22

A backlight unit comprising:
a light-emitting device having a flip chip structure;
a first reflector disposed to surround a first area including the light-emitting device and a periphery of the light-emitting device;
a color resin disposed in the first area;
an adhesive film disposed above the color resin to be spaced apart from the color resin by a predetermined distance;
a light path modulator above the light-emitting device and on the color resin; and
a light modifying sheet disposed on the adhesive film and including a light modifying pattern disposed to correspond to a position of the light-emitting device,
wherein the adhesive film is on the light path modulator,
wherein the light path modulator overlaps with the light-modifying pattern, and
wherein the light path modulator is located within a hole in the first area and surrounded by the color resin, the first reflector, and the adhesive film.

### Claim 23 (depends on 22)

The backlight unit of claim 22, further comprising:
a material disposed between the adhesive film and the color resin and having a refractive index different from a refractive index of the color resin.

### Claim 24 (depends on 22)

The backlight unit of claim 22, wherein the first reflector has a height higher than a height of the color resin.

### Claim 25 (depends on 22)

The backlight unit of claim 22, further comprising a substrate including a groove corresponding to the first area, and wherein a reflective film is applied to the substrate.

### Claim 26 (depends on 22)

The backlight unit of claim 22, further comprising:
a phosphor film disposed above the light modifying sheet and including a phosphor having a color different from a color of the color resin.

### Claim 27 (depends on 22)

The backlight unit of claim 22, wherein the color resin comprises two types of phosphors having different colors.

### Claim 28 (depends on 22)

The backlight unit of claim 22, further comprising:
a second reflector disposed on an upper face of the light-emitting device.

### Claim 29

A display device comprising:
a display panel;
a backlight unit disposed below the display panel and configured to radiate light to the display panel,
wherein the backlight unit comprises:
a light-emitting device having a flip chip structure;
a first reflector disposed to surround a first area including the light-emitting device and a periphery of the light-emitting device;
a color resin disposed in the first area;
an adhesive film disposed above the color resin to be spaced apart from the color resin by a predetermined distance;
a light path modulator above the light-emitting device and on the color resin; and
a light modifying sheet disposed on the adhesive film and including a light modifying pattern disposed to correspond to a position of the light-emitting device,
wherein the adhesive film is on the light path modulator,
wherein the light path modulator overlaps with the light modifying pattern, and
wherein the light path modulator is located within a hole in the first area and surrounded by the color resin, the first reflector, and the adhesive film.

### Claim 30 (depends on 29)

The display device of claim 29, further comprising:
a material disposed between the adhesive film and the color resin and having a refractive index different from a refractive index of the color resin.

### Claim 31 (depends on 29)

The display device of claim 29, wherein the first reflector has a height higher than a height of the color resin.

### Claim 32 (depends on 29)

The display device of claim 29, wherein the backlight unit further comprises a substrate including a groove corresponding to the first area, and wherein a reflective film is applied to the substrate.

### Claim 33 (depends on 29)

The display device of claim 29, further comprising:
a phosphor film disposed above the light modifying sheet and including a phosphor having a color different from a color of the color resin.

### Claim 34 (depends on 29)

The display device of claim 29, wherein the color resin comprises two types of phosphors having different colors.

### Claim 35 (depends on 29)

The display device of claim 29, further comprising:
a second reflector disposed on an upper face of the light-emitting device.