# US 11,307,333 B2 · Asymmetric turning film with top-hat light output distributions

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- Number: US 11,307,333 B2
- Document ID: US11307333B2
- Status: Granted
- Kind: B2
- Application number: 16/475,186
- Filed: 2018-01-03
- Published: 2019-11-07
- Granted: 2022-04-19
- Earliest claimed: 2017-01-04
- Assignees: 3M Innovative Properties Company
- Applicants: 3M Innovative Properties Company
- Inventors: Robert M. Emmons; Kenneth A. Epstein
- Web page: https://patentgrep.com/patent/US11307333B2

## CPC

- G02B 5/045: {Prism arrays}
- F21V 5/02: of prismatic shape (F21V5/04 takes precedence)
- G02B 5/0215: {the surface having a regular structure}
- G02B 5/0278: {used in transmission}
- G02B 6/0053: {Prismatic sheet or layer; Brightness enhancement element, sheet or layer}
- G02F 1/133607: {the light controlling member including light directing or refracting elements, e.g. prisms or lenses}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- 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

An optical system including a light guide and a turning film that includes a first major surface, where the first major surface is substantially smooth and a second major surface including a plurality of asymmetric microstructures each respective asymmetric microstructure including a first side, where the first side is substantially planar, and a second side including a first surface segment defining a substantially planar surface and a second surface segment defining a non-planar surface.

## Claims

### Claim 1

An optical system, comprising:
a light guide; and
a turning film, comprising:
a first major surface, wherein the first major surface is substantially smooth; and
a second major surface comprising a plurality of asymmetric microstructures each respective asymmetric microstructure, comprising:
a first side, wherein the first side is substantially planar; and
a second side, comprising:
a first surface segment defining a substantially planar surface; and
a second surface segment defining a non-planar surface,
wherein a full width at 90% maximum relative brightness is at least 35% as wide as a full width at 20% maximum relative brightness,
wherein an output distribution of relative brightness to down-guide angle includes a flat-top region between −15 and 5 degrees having less than 5% peak to valley variability of the output distribution.

### Claim 2 (depends on 1)

The optical system of claim 1, wherein the first surface segment extends from a vertex at the intersection of the first side and the second side to a first transition point, wherein the second surface segment extends from the first transition point towards a valley between the respective asymmetric microstructure and an adjacent asymmetric microstructure, wherein the full width at 90% maximum relative brightness is at least 40% as wide as the full width at 20% maximum relative brightness, wherein an output distribution of relative brightness to down-guide angle includes a flat-top region between −20 and 10 degrees having less than 5% peak to valley variability of the output distribution.

### Claim 3 (depends on 1)

The optical system of claim 1, wherein the first surface segment extends from a valley between the respective asymmetric microstructure and an adjacent asymmetric microstructure to a first transition point, wherein the second surface segment extends from the first transition point towards a vertex at the intersection of the first side and the second side, wherein the full width at 90% maximum relative brightness is at least 45% as wide as the full width at 20% maximum relative brightness.

### Claim 4 (depends on 1)

The optical system of claim 1, wherein each of the plurality of asymmetric microstructures are substantially the same lateral cross-sectional shape.

### Claim 5 (depends on 1)

The optical system of claim 1, wherein the first major surface defines a reference plane substantially parallel to the first major surface, wherein a first angle of the first surface segment is between about 40 degrees and about 70 degrees relative to the reference plane.

### Claim 6 (depends on 1)

The optical system of claim 1, wherein the shape of the second surface segment is based on a cubic equation.

### Claim 7 (depends on 1)

The optical system of claim 1, wherein at least about 60 percent of light originating from the light guide and exiting through the first major surface is included in a first set of characteristic viewing angles, wherein the first major surface defines a center viewing angle normal to the first major surface.

### Claim 8 (depends on 1)

The optical system of claim 1, wherein at least 60 percent of light originating from the light guide and exiting through the first major surface is included in a first set of characteristic viewing angles, wherein the first major surface defines a center viewing angle normal to the first major surface, wherein the first set of characteristic viewing angles is between about −20 degrees and about 20 degrees relative to the center viewing angle.

### Claim 9 (depends on 1)

The optical system of claim 1, the second side further comprising a third surface segment defining a substantially planar surface.

### Claim 10 (depends on 2)

The optical system of claim 2, wherein the second surface segment is substantially convex.

### Claim 11 (depends on 2)

The optical system of claim 2, wherein a distance between the vertex and the first transition point is between about 3 percent to about 15 percent of a distance between the vertex and the valley of the respective asymmetric microstructure.

### Claim 12 (depends on 2)

The optical system of claim 2, wherein a distance between the first transition point and the valley is between about 85 percent to about 97 percent of a distance between the vertex and the valley of the respective asymmetric microstructure.

### Claim 13 (depends on 11)

The optical system of claim 11, wherein the second surface segment is substantially concave.

### Claim 14 (depends on 3)

The optical system of claim 3, wherein a distance between the valley and the first transition point is between about 3 percent to about 50 percent of a distance between the vertex and the valley of the respective asymmetric microstructure.

### Claim 15 (depends on 3)

The optical system of claim 3, wherein a distance between the first transition point and the vertex is between about 50 percent to about 90 percent of a distance between the vertex and the valley of the respective asymmetric microstructure.

### Claim 16 (depends on 5)

The optical system of claim 5, wherein the shape of the first surface segment is based on a first linear equation, wherein the shape of the second surface segment is based on a cubic equation, wherein a first derivative of the cubic equation matches the first linear equation.

### Claim 17 (depends on 5)

The optical system of claim 5, wherein the first angle is based on a first linear equation, wherein the shape of the second surface segment is based on a fourth or higher order equation, wherein a first derivative of the fourth or higher order equation matches the first linear equation.

### Claim 18 (depends on 7)

The optical system of claim 7, wherein the first set of characteristic viewing angles is between about −35 degrees and about 35 degrees relative to the center viewing angle.

### Claim 19 (depends on 9)

The optical system of claim 9, wherein a second angle of the third surface segment is between about 40 degrees and about 70 degrees relative to a reference plane substantially parallel to the first major surface.

### Claim 20 (depends on 9)

The optical system of claim 9, wherein at least 60 percent of light originating from the light guide and exiting through the first major surface is included in a first set of characteristic viewing angles, wherein the first major surface defines a center viewing angle normal to the first major surface.

### Claim 21 (depends on 9)

The optical system of claim 9, wherein at least 60 percent of light originating from the light guide and exiting through the first major surface is included in a first set of characteristic viewing angles, wherein the first major surface defines a center viewing angle normal to the first major surface, wherein the first set of characteristic viewing angles is between about −20 degrees and about 20 degrees relative to the center viewing angle.

### Claim 22 (depends on 19)

The optical system of claim 19, wherein the light guide inputs light into the turning film at a light input distribution, wherein the first angle, the cubic equation, and the second angle are based on the light input distribution.

### Claim 23 (depends on 20)

The optical system of claim 20, wherein the first set of characteristic viewing angles is between about −35 degrees and about 35 degrees relative to the center viewing angle relative to the center viewing angle.