# US 11,993,055 B2 · Flexible display device and upper film therefor

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- Number: US 11,993,055 B2
- Document ID: US11993055B2
- Status: Granted
- Kind: B2
- Application number: 17/902,477
- Filed: 2022-09-02
- Published: 2023-06-08
- Granted: 2024-05-28
- Earliest claimed: 2021-12-03
- Assignees: Samsung Display Co., Ltd.
- Applicants: Samsung Display Co., LTD.
- Inventors: Seung Hwan Chung; Hung Kun Ahn; Seokwon Jang; Danbi Myung
- Web page: https://patentgrep.com/patent/US11993055B2

## CPC

- B32B 15/04: comprising metal as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a bituminous or tarry layer B32B11/08; next to a water-setting substance layer B32B13/06; next to a glass layer B32B17/061; next to a cellulosic plastic layer B32B23/042)}
- B32B 7/02: Physical, chemical or physicochemical properties
- B32B 23/00: Layered products comprising {a layer of} cellulosic plastic substances {, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose}
- B32B 23/08: of synthetic resin
- B32B 23/20: comprising esters
- B32B 27/08: of synthetic resin
- B32B 27/281: {comprising polyimides}
- B32B 27/308: {comprising acrylic (co)polymers}
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- B32B 27/325: {comprising polycycloolefins}
- B32B 27/36: comprising polyesters
- B32B 27/365: {comprising polycarbonates}
- B32B 27/40: comprising polyurethanes
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 2255/10: on synthetic resin layer or on natural or synthetic rubber layer
- B32B 2270/00: Resin or rubber layer containing a blend of at least two different polymers
- B32B 2307/412: Transparent
- B32B 2307/414: Translucent
- B32B 2307/42: Polarizing, birefringent, filtering
- B32B 2307/518: bi-axially
- B32B 2307/546: Flexural strength; Flexion stiffness
- B32B 2307/552: Fatigue strength
- B32B 2307/558: Impact strength, toughness
- B32B 2307/732: Dimensional properties
- B32B 2307/7376: Thickness
- B32B 2457/20: Displays, e.g. liquid crystal displays, plasma displays
- Y02E 10/549: Organic PV cells
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

The disclosure relates to a flexible display device including: a display panel including a touch sensor, where the display panel is foldable with respect to a folding axis; a cover window disposed on a front surface of the display panel; and a front surface film disposed on a front surface of the cover window, where the front surface film includes a protection film, and a base film having a transverse direction, and the transverse direction is perpendicular to a direction of the folding axis.

## Claims

### Claim 1

A flexible display device comprising:
a display panel including a touch sensor, wherein the display panel is foldable with respect to a folding axis;
a cover window disposed on a front surface of the display panel; and
a front surface film disposed on a front surface of the cover window,
wherein the front surface film includes:
a protection film; and
a base film which is a biaxially elongated film having elongating directions including a transverse direction and a machine direction perpendicular to the transverse dirction,
wherein a value of a modulus of the base film in the transverse direction is greater than a value thereof in the machine direciton, and
wherin the transverse direction is perpendicular to a direction of the folding axis.

### Claim 2 (depends on 1)

The flexible display device of claim 1, wherein
a thickness of the protection film is equal to or greater than about 20 μm and equal to or less than about 80% of a thickness of the base film.

### Claim 3 (depends on 2)

The flexible display device of claim 2, wherein
the protection film is disposed on a rear surface of the base film.

### Claim 4 (depends on 2)

The flexible display device of claim 2, wherein
the protection film includes a polyurethane, a mixed resin including a polyurethane, or a copolymer including a resin including a urethane functional group.

### Claim 5 (depends on 2)

The flexible display device of claim 2, wherein
the base film includes at least one selected from a polyimide, a polycarbonate, a polymethyl methacrylate, a polyethylene terephthalate, a cycloolefin polymer, and a triacetyl cellulose.

### Claim 6 (depends on 5)

The flexible display device of claim 5, wherein
the base film has a thickness of equal to or greater than about 50 μm and equal to or less than about 125 μm.

### Claim 7 (depends on 6)

The flexible display device of claim 6, wherein
a radius of curvature of the flexible display device in a bent state is about 1.5 mm.

### Claim 8 (depends on 6)

The flexible display device of claim 6, wherein
the protection film or the base film has a haze value of equal to or less than about 2% and transmittance of equal to or greater than about 85%.

### Claim 9 (depends on 2)

The flexible display device of claim 2, wherein
the front surface film further includes a hard coating layer disposed on a front surface of the base film.

### Claim 10 (depends on 2)

The flexible display device of claim 2, further comprising:
a lower film attached to a rear surface of the display panel.

### Claim 11 (depends on 2)

The flexible display device of claim 2, further comprising:
a polarizer disposed between the display panel and the cover window.

### Claim 12 (depends on 2)

The flexible display device of claim 2, wherein
the display panel includes a first display area including a plurality of pixels and a second display area including a light transmitting region,
wherein the second display area corresponds to an optical element including a camera or a photosensor.

### Claim 13

An upper film for a flexible display device comprising:
a protection film including a polyurethane; and
a base film which is biaxially elongated film having elongating directions including a transverse direction and a machine direction perpendicular to the transverse direction,
wherein a value of a modulus of the base film in the transverse direction is greater than a value thereof in the machine direction, and
wherien a thickness of the protection film is equal to or greater than about 20 μm and equal to or less than about 80% of a thickness of the base film.

### Claim 14 (depends on 13)

The upper film for a flexible display device of claim 13, wherein
the protection film is disposed on a rear surface of the base film.

### Claim 15 (depends on 13)

The upper film for a flexible display device of claim 13, wherein
the protection film includes a polyurethane, a mixed resin including a polyurethane, or a copolymer including at least one resin including a urethane functional group.

### Claim 16 (depends on 13)

The upper film for a flexible display device of claim 13, wherein
the base film includes at least one selected from a polyimide, a polycarbonate, a polymethyl methacrylate, a polyethylene terephthalate, a cycloolefin polymer, and a triacetyl cellulose.

### Claim 17 (depends on 16)

The upper film for a flexible display device of claim 16, wherein
the base film has a thickness of equal to or greater than about 50 μm and equal to or less than about 125 μm.

### Claim 18 (depends on 17)

The upper film for a flexible display device of claim 17, wherein
a radius of curvature of the flexible display device in a bent state is about 1.5 mm.

### Claim 19 (depends on 17)

The upper film for a flexible display device of claim 17, wherein
the protection film or the base film has a haze value of equal to or less than about 2% and transmittance of equal to or greater than about 85%.

### Claim 20 (depends on 13)

The upper film for a flexible display device of claim 13, wherein
the upper film further includes a hard coating layer disposed on a front surface of the base film.