Display system, angled light control film, and method of making angled light control film

Abstract

A method of making an angled light control film (LCF) includes providing an LCF. The LCF includes alternating light transmissive regions and light absorbing regions disposed between a light input surface and a light output surface. The light transmissive regions extend along a same in-plane first direction and are arranged along an in-plane orthogonal second direction. Each of the light transmissive regions has a top surface and sidewalls. Each of the light absorbing regions has a bottom surface disposed between two adjacent light transmissive regions. The method further includes applying a compressive force to at least one of the light input surface and the light output surface of the LCF along the second direction to obtain the angled LCF.

Description

PA103765W002DISPLAY SYSTEM, ANGLED LIGHT CONTROL FILM, AND METHOD OF MAKING ANGLED LIGHT CONTROL FILMTechnical Field

[0001] The present disclosure relates to an angled light control film and a display system. The present disclosure further relates to a method of making the angled light control film.Background

[0002] Light control films (LCF) are configured to regulate the transmission of light. LCFs typically include a light transmissive film having a plurality of light absorbing regions that include a light-absorbing material. The LCFs can be placed proximate a surface, such as a display surface, an image surface, or any other surface including an image to be viewed. Typically, the LCFs provide symmetric light output with maximum optical transmission such as peak brightness at center or on-axis (i.e., near a central viewing angle) and falls off gradually at wider angles. The aforesaid LCFs can provide privacy (e.g., for laptops, ATM) or safety (e.g., for windshield light reflection mitigation in cars).Summary

[0003] In a first aspect, the present disclosure provides a method of making an angled light control film (LCF). The method includes providing an LCF. The LCF includes alternating light transmissive regions and light absorbing regions disposed between a light input surface and a light output surface. The light transmissive regions extend along a same in-plane first direction and are arranged along an in-plane orthogonal second direction. Each of the light transmissive regions has a top surface and sidewalls. Each of the light absorbing regions has a bottom surface disposed between two adjacent light transmissive regions. The method further includes applying a compressive force to at least one of the light input surface and the light output surface of the LCF along the second direction to obtain the angled LCF.

[0004] In a second aspect, the present disclosure provides an angled light control film (LCF). The angled LCF includes a light input surface and a light output surface opposite the light input surface. The angled LCF further includes alternating light transmissive regions and light absorbing regions disposed between the light input surface and the light output surface. The light transmissive regions include first and second light transmissive regions. The first light transmissive regions extend along a same in-plane first direction and are arranged along an in-plane orthogonal second direction. Each of the first light transmissive regions has a top surface and sidewalls. Each of the second light transmissive region has a bottom surface disposed between two adjacent light absorbing regions and is at least partially disposed on the top surface of an adjacent first light transmissive region. Each of the sidewalls is inclined at an inclination angle greater than about 2 degrees with respect to a normalfrom the bottom surface along the second direction. The first light transmissive regions have a unitary construction. Each of the sidewalls include a first portion extending from the top surface and a second portion extending from the first portion to the bottom surface. The first portion is inclined at a first inclination angle and the second portion is inclined at a second inclination angle with respect to the normal from the bottom surface. The first inclination angle is greater than the second inclination angle.

[0005] In a third aspect, the present disclosure provides an angled light control film (LCF). The angled LCF includes a light input surface and a light output surface opposite the light input surface. The angled LCF further includes alternating light transmissive regions and light absorbing regions disposed between the light input surface and the light output surface. The light transmissive regions include first and second light transmissive regions. The first light transmissive regions extend along a same in-plane first direction and are arranged along an in-plane orthogonal second direction. Each of the first light transmissive regions has a top surface and sidewalls. Each of the second light transmissive region has a bottom surface disposed between two adjacent light absorbing regions and is at least partially disposed on the top surface of an adjacent first light transmissive region. Each of the sidewalls is inclined at an inclination angle greater than about 2 degrees with respect to a normal from the bottom surface along the second direction. The first light transmissive regions have a unitary construction.

[0006] In a fourth aspect, the present disclosure provides a display system for use in a vehicle. The display system includes a display configured to form and emit an image for viewing by an eye of one or more occupants of the vehicle. The display system further includes the angled LCF of the third aspect disposed on the display. The light input surface faces the display and the light output surface faces the eye. The angled LCF is configured to receive the emitted image and transmit an angled image toward the one or more occupants.

[0007] The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.Brief Description of the Drawings

[0008] Exemplary embodiments disclosed herein may be more completely understood in consideration of the following detailed description in connection with the following figures. The figures are not necessarily drawn to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

[0009] FIG. 1 A is a schematic sectional view of an exemplary light control film (LCF);

[0010] FIG. IB is a schematic sectional view of an exemplary LCF;

[0011] FIG. 2 is a flowchart depicting a method of making an angled LCF, according to an embodiment of the present disclosure;

[0012] FIG. 3 is a schematic setup of the method of making the angled LCF, according to an embodiment of the present disclosure;

[0013] FIG. 4 is a schematic view of a step of making a microstructured film, according to an embodiment of the present disclosure;

[0014] FIG. 5 is a schematic sectional view of the microstructured film, according to an embodiment of the present disclosure;

[0015] FIG. 6 is a schematic view of a step of making the LCF shown in FIG. 1A, according to an embodiment of the present disclosure;

[0016] FIG. 7 is a schematic view of another step of making the LCF shown in FIG. 1A, according to an embodiment of the present disclosure;

[0017] FIG. 8 is a schematic view of a display system, according to an embodiment of the present disclosure;

[0018] FIG. 9 is a schematic view of exemplary vehicles;

[0019] FIG. 10 is a schematic sectional view of the angled LCF, according to an embodiment of the present disclosure;

[0020] FIG. 11 is an image depicting the angled LCF, according to an embodiment of the present disclosure;

[0021] FIGS. 12A and 12B are magnified images of the angled LCF, according to an embodiment of the present disclosure;

[0022] FIG. 13 is an exemplary conoscopic plot of an optical transmission of the angled LCF as a function of viewing angle; and

[0023] FIG. 14 is an exemplary graph depicting optical transmissions of a comparative LCF and the angled LCF as a function of viewing angle.Detailed Description

[0024] In the following description, reference is made to the accompanying figures that form a part thereof and in which various embodiments are shown by way of illustration. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

[0025] In the following disclosure, the following definitions are adopted.

[0026] As used herein, all numbers should be considered modified by the term “about”. As used herein, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably.

[0027] As used herein as a modifier to a property or attribute, the term “generally”, unless otherwise specifically defined, means that the property or attribute would be readily recognizable by aperson of ordinary skill but without requiring absolute precision or a perfect match (e.g., within + / - 20 % for quantifiable properties).

[0028] The term “substantially”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 10% for quantifiable properties) but again without requiring absolute precision or a perfect match.

[0029] The term “about”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 5% for quantifiable properties) but again without requiring absolute precision or a perfect match.

[0030] As used herein, the terms “first” and “second” are used as identifiers. Therefore, such terms should not be construed as limiting of this disclosure. The terms “first” and “second” when used in conjunction with a feature or an element can be interchanged throughout the embodiments of this disclosure.

[0031] As used herein, “at least one of A and B” should be understood to mean “only A, only B, or both A and B”.

[0032] Light control films (LCF) are configured to regulate the transmission of light. LCFs typically include a light transmissive film having a plurality of light absorbing regions that include a light-absorbing material. The LCFs can be placed proximate a surface, such as a display surface, an image surface, or any other surface including an image to be viewed. Typically, the LCFs provide symmetric light output with maximum optical transmission such as peak brightness at center or on-axis (i.e., near a central viewing angle) and falls off gradually at wider angles. The aforesaid LCFs can provide privacy (e.g., for laptops, ATM) or safety (e.g., for windshield light reflection mitigation in cars).

[0033] However, in certain applications such as in display of a vehicle, the LCFs may be required to provide and regulate the maximum optical transmission at off-axis / away from the center. In such applications, control on the visibility of information appearing in the display towards occupants that are positioned away from the center, for example, to provide desired visual information to driver or passenger in the vehicle, or to avoid distraction of the driver, is required. Therefore, there is a need for an LCF with the maximum optical transmission at off-axis locations.

[0034] The present disclosure relates to a method of making an angled light control film (LCF) and the angled LCF.

[0035] The method includes providing an LCF. The LCF includes alternating light transmissive regions and light absorbing regions disposed between a light input surface and a light output surface. The light transmissive regions extend along a same in-plane first direction and are arranged along an in-plane orthogonal second direction. Each of the light transmissive regions has a top surface and sidewalls. Each of the light absorbing regions has a bottom surface disposed between two adjacent light transmissive regions. The method further includes applying a compressive force to at least oneof the light input surface and the light output surface of the LCF along the second direction to obtain the angled LCF.

[0036] The angled LCF includes a light input surface and a light output surface opposite the light input surface. The angled LCF further includes alternating light transmissive regions and light absorbing regions disposed between the light input surface and the light output surface. The light transmissive regions include first and second light transmissive regions. The first light transmissive regions extend along a same in-plane first direction and are arranged along an in-plane orthogonal second direction. Each of the first light transmissive regions has a top surface and sidewalls. Each of the second light transmissive region has a bottom surface disposed between two adjacent light absorbing regions and is at least partially disposed on the top surface of an adjacent first light transmissive region. Each of the sidewalls is inclined at an inclination angle greater than about 2 degrees with respect to a normal from the bottom surface along the second direction. The first light transmissive regions have a unitary construction. Each of the sidewalls include a first portion extending from the top surface and a second portion extending from the first portion to the bottom surface. The first portion is inclined at a first inclination angle and the second portion is inclined at a second inclination angle with respect to the normal from the bottom surface. The first inclination angle is greater than the second inclination angle.

[0037] The disclosed angled LCF may provide a maximum optical transmission at off-axis locations, which may be desired in display systems of vehicles. Specifically, the method of making the angled LCF may provide the alternating light transmissive regions and the light absorbing regions inclined at an inclination angle in a same direction. This may provide the maximum optical transmission at the off-axis locations and reduce optical transmission at the on-axis locations.Therefore, the angled LCF may be suitable for applications in which an intended viewer is not sitting directly in front of a display (viewing angle of about 0 degree), such as in the display systems of the vehicles.

[0038] Further, the method of making the angled LCF of the present disclosure may be simple and cost-effective. Further, the angled LCF made using the method of the present disclosure may include the first light transmissive regions having the unitary construction. The first light transmissive regions may therefore not include an internal interface, which may otherwise cause diffraction or internal reflections, which may further cause optical artifacts.

[0039] Referring now to the figures, FIG. 1 A illustrates a schematic sectional view of an exemplary light control film (LCF) 102a. FIG. IB illustrates a schematic sectional view of an exemplary LCF 102b. The LCFs 102a, 102b may be collectively referred to as “the LCF 102” herein.

[0040] The LCF 102 defines mutually orthogonal x, y, and z-axes. The x-axis is defined along a length of the LCF 102, while the y-axis is defined along a width of the LCF 102. The z-axis is defined along a thickness of the LCF 102.

[0041] The LCF 102 includes alternating light transmissive regions 104 and light absorbing regions 106 disposed between a light input surface 108 and a light output surface 110. The light transmissive regions 104 extend along a same in-plane first direction and are arranged along an inplane orthogonal second direction. The first direction extends substantially along the y-axis. The second direction extends substantially along the x-axis.

[0042] Each of the light transmissive regions 104 has a top surface 112 and sidewalls 114 and each of the light absorbing regions 106 has a bottom surface 116 disposed between two adjacent light transmissive regions 104. In some embodiments, the sidewalls 114 of the light transmissive regions 104 are substantially parallel.

[0043] FIG. 2 illustrates a flowchart depicting a method 800 of making an angled LCF 100 (shown in FIG. 3), according to an embodiment of the present disclosure. FIG. 3 illustrates a schematic setup of the method 800 of making the angled LCF 100, according to an embodiment of the present disclosure.

[0044] Referring to FIGS. 2 and 3, at step 802, the method 800 includes providing the LCF 102 (shown in FIGS. 1 A and IB).

[0045] At step 804, the method 800 further includes applying a compressive force to at least one of the light input surface 108 and the light output surface 110 of the LCF 102 along the second direction (i.e., substantially along the x-axis) to obtain the angled LCF 100. In some embodiments, applying the compressive force includes providing the compressive force on each of the light input surface 108 and the light output surface 110 of the LCF 102.

[0046] In some embodiments, the compressive force is applied to each of the light input surface 108 and the light output surface 110 of the LCF 102 by respective first and second rollers 118, 120 rotating in respective first and second rotational directions and having respective first and second rotational speeds. In some embodiments, the first rotational direction is clockwise or counterclockwise. In some embodiments, the second rotational direction is clockwise or counterclockwise.

[0047] In some embodiments, the first and second rotational directions are the same and the first and second rotational speeds are the same. As illustrated in FIG. 3, the first and second rotational directions are the same. In some embodiments, the first and second rotational directions are the same and the first and second rotational speeds are different. Further, in the illustrated embodiment of FIG.3, the first and second rollers 118, 120 are shown directly opposite and impinging each of the light input surface 108 and the light output surface 110 of the LCF 102 while it is moving. However, the first and second rollers 118, 120 may not be directly opposite to each other. Further, one of the first and second rollers 118, 120 may be undriven while the other of the first and second rollers 118, 120 is rotating.

[0048] In some embodiments, the first and second rotational directions are different and the first and second rotational speeds are different. In some embodiments, the compressive force to at leastone of the light input surface 108 and the light output surface 110 of the LCF 102 is applied simultaneously or at different times.

[0049] FIG. 4 illustrates a schematic view of a step of making a microstructured film 122, according to an embodiment of the present disclosure. FIG. 5 illustrates a schematic sectional view of the microstructured film 122, according to an embodiment of the present disclosure.

[0050] Referring to FIGS. 2 to 5, in some embodiments, the method 800 further includes providing the microstructured film 122. The microstructured film 122 includes the light transmissive regions 104 alternated with channels 124. The microstructured film 122 has a microstructured surface 126 defined by the plurality of light transmissive regions 104 and the channels 124. Specifically, the microstructured film 122 has the microstructured surface 126 defined by the top surface 112 and the sidewalls 114 of the light transmissive regions 104 and a channel bottom surface 128 of the channels 124. The microstructured film 122 further has a non-microstructured surface 132 opposite to the microstructured surface 126.

[0051] In some embodiments, the method 800 further includes providing a first substrate 150. The method 800 further includes depositing a polymeric layer 154 on the first substrate 150. The method 800 further includes microreplicating the polymeric layer 154 to obtain the microstructured film 122.

[0052] Referring to FIGS. 2 and 5, in some embodiments, the method 800 further includes filling the channels 124 of the microstructured film 122 with a light absorbing material 134 to obtain the LCF 102b shown in FIG. IB.

[0053] In some embodiments, the method 800 further includes, prior to applying the compressive force, providing a second substrate 152 (shown in FIG. 3) opposite to the first substrate 150.

[0054] FIG. 6 illustrates a schematic view of a step of making the LCF 102a shown in FIG. 1A, according to an embodiment of the present disclosure.

[0055] Referring to FIGS. 2, 5, and 6, in some embodiments, the method 800 further includes applying the light absorbing material 134 to the microstructured surface 126. In some embodiments, the light absorbing material 134 includes a pigment and / or dye. In some embodiments, the light absorbing material 134 includes a plurality of light absorbing particles. In some embodiments, the plurality of light absorbing particles includes carbon black.

[0056] As shown in FIG. 6, in some embodiments, applying the light absorbing material 134 includes layer-by-layer self-assembly.

[0057] FIG. 7 illustrates a schematic view of another step of making the LCF 102a shown in FIG. 1A, according to an embodiment of the present disclosure. In the illustrated example of FIGS. 3-7, the light transmissive regions 104 run downweb but are shown crossweb for ease of illustration.

[0058] Referring to FIGS. 2, 5, 6, and 7, in some embodiments, the method 800 further includes removing at least a portion of the light absorbing material 134 from the top surface 112 of the light transmissive regions 104 and the channel bottom surface 128 of the channels 124.

[0059] In some embodiments, removing the at least a portion of the light absorbing material 134 includes reactive ion etching.

[0060] Referring to FIGS. 1A, 2, and 7, in some embodiments, the method 800 further includes filling the channels 124 with a polymeric material to obtain the LCF 102a. In some embodiments, the method 800 further includes laminating the LCF 102a to the second substrate 152 (shown in FIG. 3) opposite to the first substrate 150.

[0061] In some embodiments, the polymeric material includes a polymerizable resin. In some embodiments, the method 800 further includes curing the polymerizable resin. In some embodiments, the polymeric material is the same polymeric material as of the microstructured film 122. The same polymeric material within the channels 124 and the microstructured film 122 may alter the light output distribution.

[0062] In some embodiments, the method 800 further includes transferring the angled LCF 100 to a display 502 (shown in FIG. 8) to obtain a display system 500 (shown in FIG. 8).

[0063] FIG. 8 illustrates a schematic view of the display system 500, according to an embodiment of the present disclosure. FIG. 9 illustrates schematic views of exemplary vehicles 508.

[0064] Referring to FIGS. 8 and 9, the display system 500 for use in the vehicle 508 includes the display 502. The display 502 is configured to form and emit an image 504 for viewing by an eye 506 of one or more occupants 510 of the vehicle 508. In some embodiments, the display 502 includes an organic light emitting diode (OLED) display. In some embodiments, the display 502 includes a liquid crystal display (LCD) panel.

[0065] The display system 500 further includes the angled LCF 100 disposed on the display 502. The angled LCF 100 includes a light input surface 208 and a light output surface 210 opposite the light input surface 208. The light input surface 208 faces the display 502 and the light output surface 210 faces the eye 506. The angled LCF 100 is configured to receive the emitted image 504 and transmit an angled image 512 toward the one or more occupants 510.

[0066] In some embodiments, the one of the one or more occupants 510 of the vehicle 508 is a driver 510a (shown in FIG. 9) of the vehicle 508. In some embodiments, the one of the one or more occupants 510 of the vehicle 508 is a passenger 510b (shown in FIG. 9) of the vehicle 508. In some embodiments, the vehicle 508 is a car 508a, a truck 508b, a bus 508c, a train 508d, a ship 508e, a boat 508f, an airplane 508g, or a helicopter 508h.

[0067] In some embodiments, the eye 506 of a first occupant 510’ of the one or more occupants 510 of the vehicle 508 is positioned in a first viewing space 522 allowing the first occupant 510’ to view the angled image 512 at a first brightness. The eye 506 of a second occupant 510” of the one or more occupants 510 of the vehicle 508 is positioned in a different second viewing space 524 allowing the second occupant 510” to view the angled image 512 at a second brightness. In some embodiments, a ratio of magnitudes of the first and second brightness is greater than about 1.25. Insome embodiments, the ratio of magnitudes of the first and second brightness is greater than about 1.3, greater than about 1.35, greater than about 1.4, greater than about 1.45, or greater than about 1.5.

[0068] FIG. 10 illustrates a schematic sectional view of the angled LCF 100, according to an embodiment of the present disclosure. FIG. 11 illustrates an image of the angled LCF 100, according to an embodiment of the present disclosure.

[0069] Referring to FIGS. 3, 10, and 11, the angled LCF 100 further includes alternating light transmissive regions 204 and light absorbing regions 206 disposed between the light input surface 208 and the light output surface 210.

[0070] The light transmissive regions 204 includes first and second light transmissive regions 204a, 204b. The first light transmissive regions 204a extend along a same in-plane first direction and arranged along an in-plane orthogonal second direction. The first direction extends substantially along the y-axis. The second direction extends substantially along the x-axis.

[0071] Each of the first light transmissive regions 204a has a top surface 212 and sidewalls 214. The first light transmissive regions 204a have a unitary construction. The unitary construction of the first light transmissive regions 204a may not include an internal interface, which may otherwise cause diffraction or internal reflections, which may further cause optical artifacts.

[0072] Further, each of the second light transmissive region 204b has a bottom surface 216 disposed between two adjacent light absorbing regions 206 and is at least partially disposed on the top surface 212 of an adjacent first light transmissive region 204a.

[0073] In some embodiments, the top surface 212 of each of the first light transmissive regions 204a is inclined with respect to the light output surface 210. In some embodiments, a first angle tl of the top surface 212 of each of the first light transmissive regions 204a with respect to the light input surface 208 is from about 2 degrees to about 40 degrees. In some embodiments, the first angle tl of the top surface 212 of each of the first light transmissive regions 204a with respect to the light input surface 208 is greater than about 5 degrees. In some embodiments, the first angle tl is about 10 degrees, about 15 degrees, about 20 degrees, about 25 degrees, or about 30 degrees.

[0074] In some embodiments, the bottom surfaces 216 of the second light transmissive regions 204b substantially lie in a same plane which is substantially parallel to the light input surface 208. For example, the bottom surfaces 216 of the second light transmissive regions 204b substantially lie in the x-y plane.

[0075] As shown in FIG. 11, in some embodiments, in a sectional view along a third direction perpendicular to each of the first direction and the second direction, the top surfaces 212 of the first light transmissive regions 204a and lines 218 joining the adjacent top surfaces 212 follow a zig-zag pattern 219 extending along the second direction (i.e., substantially along the x-axis). The third direction extends substantially along the z-axis.

[0076] Referring to FIGS. 10 and 11, each of the sidewalls 214 is inclined at an inclination angle al greater than about 2 degrees with respect to a normal from the bottom surface 216 along the seconddirection. In some embodiments, the sidewalls 214 are inclined at the inclination angle al greater than about 5 degrees, greater than about 10 degrees, greater than about 15 degrees, greater than about 20 degrees, or greater than about 25 degrees. In some embodiments, the sidewalls 214 are inclined at the inclination angle al less than about 30 degrees, less than about 25 degrees, less than about 20 degrees, less than about 15 degrees, or less than about 10 degrees.

[0077] In some embodiments, in a plan view 45 (shown in FIG. 10), the bottom surface 216 of each of the second light transmissive regions 204b is at least 10% covered by the top surface 212 of the adjacent first light transmissive region 204a. In some embodiments, in the plan view 45, the bottom surface 216 of each of the second light transmissive regions 204b is at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% covered by the top surface 212 of the adjacent first light transmissive region 204a. In some embodiments, in the plan view 45, the bottom surface 216 of each of the second light transmissive regions 204b is fully covered by the top surface 212 of the adjacent first light transmissive region 204a.

[0078] In some embodiments, the angled LCF 100 further includes at least one removable substrate 222 disposed on the light input surface 208 or the light output surface 210. As illustrated in FIG. 10, in some embodiments, the angled LCF 100 further includes the removable substrate 222 disposed on each of the light input surface 208 or the light output surface 210.

[0079] In some embodiments, the angled LCF 100 further includes a bonding layer 224 disposed between the at least one removable substrate 222 and the light input surface 208 or the light output surface 210. In the illustrated embodiment of FIG. 10, the angled LCF 100 includes the bonding layer 224 disposed between the removable substrate 222 and the light input surface 208. In some embodiments, the angled LCF 100 may be attached to the display 502 (shown in FIG. 8) of the display system 500 (shown in FIG. 8) via the bonding layer 224. In some embodiments, the removable substrate 222 may be a release liner.

[0080] FIGS. 12A and 12B illustrate magnified images of the angled LCF 100, according to an embodiment of the present disclosure.

[0081] Referring to FIGS. 10, 11, 12A, and 12B, in some embodiments, each of the sidewalls 214 includes a first portion 214a extending from the top surface 212 and a second portion 214b extending from the first portion 214a to the bottom surface 216. The first portion 214a is inclined at a first inclination angle si and the second portion 214b is inclined at a second inclination angle s2 with respect to the normal from the bottom surface 216. The first inclination angle si is greater than the second inclination angle s2.

[0082] In some embodiments, a portion 214c of each of the sidewalls 214 extending from the top surface 212 is curved. In some embodiments, the curved portion 214c is at most about 50% of the sidewall 214. In some embodiments, the first portion 214a includes the portion 214c.

[0083] FIG. 13 illustrates a conoscopic plot of an optical transmission of the angled LCF 100 as a function of viewing angle. A viewing angle of 0 degree (center of the conoscopic plot) is orthogonalto the light output surface 210 and the viewing angles of 0 degree and 180 degrees are parallel to the light output surface 210.

[0084] FIG. 14 illustrates an exemplary graph 702 depicting optical transmissions of a comparative LCF (e.g., the LCF 102) and the angled LCF 100 (shown in FIG. 1 A and IB) as a function of viewing angle.

[0085] The optical transmission is expressed in the ordinate. The viewing angle is expressed in degrees in the abscissa.

[0086] Referring to FIGS. 13 and 14, the graph 702 includes curves 704, 706. The curve 704 depicts a variation in the optical transmission of the comparative LCF as the function of viewing angle. The curve 706 depicts a variation in the optical transmission of the angled LCF 100 as the function of viewing angle.

[0087] As is apparent from the curve 706, in some embodiments, the optical transmission has a full width at half maximum (FWHM) 76 extending from a first viewing angle vl to a second viewing angle v2. A magnitude of the first viewing angle vl is greater than a magnitude of the second viewing angle v2 by about 2 degrees. In some embodiments, the magnitude of the first viewing angle vl is greater than the magnitude of the second viewing angle v2 by about 3 degrees, about 4 degrees, or about 5 degrees.

[0088] Further, in some embodiments, the angled LCF 100 has the optical transmission, as measured with a conoscope for a wavelength range of between about 400 nm to about 700 nm, having a maximum transmission 74 at a viewing angle of greater than about 2 degrees and less than about 30 degrees. In the illustrated embodiment of FIG. 14, the maximum transmission 74 is at the viewing angle of about 5 degrees. In some embodiments, the maximum transmission 74 is at a viewing angle of greater than about 5 degrees and less than about 25 degrees, greater than about 5 degrees and less than about 20 degrees, greater than about 5 degrees and less than about 20 degrees, greater than about 5 degrees and less than about 15 degrees, or greater than about 10 degrees and less than about 15 degrees.

[0089] Referring to FIGS. 2 to 14, the angled LCF 100 may provide a maximum optical transmission at off-axis locations, which may be desired in display systems (e.g., the display system) of vehicles (e.g., the vehicles 508). Specifically, the method 800 of making the angled LCF 100 may provide the alternating light transmissive regions 204 and the light absorbing regions 206 inclined at the inclination angle al in the same direction. This may provide the maximum optical transmission at the off-axis locations and reduce an optical transmission at the on-axis locations. Therefore, the angled LCF 100 may be suitable for applications in which an intended viewer (e.g., the first occupant 510’) is not sitting directly in front of a display (viewing angle of about 0 degree), such as in the display systems of the vehicles.

[0090] Further, the method 800 of making the angled LCF 100 may be simple, cost-effective. Further, the angled LCF 100 made using the method 800 may include the first light transmissiveregions 206a having the unitary construction. The first light transmissive regions 206a may therefore not include an internal interface, which may otherwise cause diffraction or internal reflections, which may further cause optical artifacts.

[0091] The disclosure is further described with reference to the following example. The example will be explained with reference to FIGS. 1A-1B to 14.

[0092] The following example is intended for illustrative purposes only, since numerous modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise noted, all parts, percentages, and ratios reported in the following example is on a weight basis.

[0093] The components of Resin A used in the cast-and-cure microreplication process (Preparative Example 1) are listed in Table 1 below. The raw materials for the layer-by-layer coating are listed in Table 2 below. The raw materials for reactive ion etching are listed in Table 3 below.Table 1Table 2Table 3Preparative Example 1 (PEI): Preparation of “Square Wave” Microstructured FilmA diamond (29.0 pm tip width, 3° included angle, 87 pm deep) was used to cut a tool having a plurality of parallel linear grooves. The grooves were spaced apart by a pitch of 62.6 microns.Resin A was prepared by mixing the materials in Table 4 provided below.Table 4

[0094] A “cast-and-cure” microreplication process was carried out with Resin A and the tool described above. The line conditions were: resin temperature 150° F., die temperature 150° F., coater IR 120° F. edges / 130° F. center, tool temperature 100° F., and line speed 70 fpm, Fusion D lamps, with peak wavelength at 385 nm, were used for curing and operated at 100% power. The resulting microstructured film comprised a plurality of protrusions (e.g. light transmissive regions) separated by channels as illustrated in FIG. 5. The protrusions of the microstructured film are a negative replication of the grooves of the tool. The protrusions have a wall angle of 1.5 degrees resulting in the protrusions being slightly tapered (wider at the light input surface and narrower at the light output surface). The channels of the microstructured film are a negative replication of the uncut portions of the tool between the grooves.

[0095] Method for Making Layer-by-Layer Self- Assembled Coatings on Microstructured Film

[0096] Layer-by-layer self-assembled coatings were made using an apparatus purchased from Svaya Nanotechnologies, Inc. (Sunnyvale, CA) and modeled after the system described in U.S. Pat. No. 8,234,998 (Krogman et al.) as well as Krogman et al. Automated Process for Improved Uniformity and Versatility of Layer-by-Layer Deposition, Langmuir 2007, 23, 3137-3141.

[0097] The apparatus comprises pressure vessels loaded with the coating solutions. Spray nozzles with a flat spray pattern (from Spraying Systems, Inc., Wheaton, Illinois) were mounted to spray the coating solutions and rinse water at specified times, controlled by solenoid valves. The pressure vessels (Alloy Products Corp., Waukesha, WI) containing the coating solutions were pressurized with nitrogen to 30 psi, while the pressure vessel containing deionized (DI) water was pressurized with air to 30 psi. Flow rates from the coating solution nozzles were each 10 gallons per hour, while flow rate from the DI water rinse nozzles were 40 gallons per hour. The substrate to be coated was adhered with epoxy (Scotch-Weld epoxy adhesive, DP100 Clear, 3M Company, St. Paul, MN) to a glass plate (12"X12"XVS" thick) (Brin Northwestern Glass Co., Minneapolis, MN), which was mounted on a vertical translation stage and held in place with a vacuum chuck. In a typical coating sequence, the polycation (e.g., PDAC) solution was sprayed onto the substrate while the stage moved vertically downward at 76 mm / sec. Next, after a dwell time of 12 sec, the DI water solutionwas sprayed onto the substrate while the stage moved vertically upward at 102 nun / sec. The substrate was then dried with an airknife at a speed of 3 mm / sec. Next, the polyanion (e.g., pigment nanoparticles) solution was sprayed onto the substrate while the stage moved vertically downward at 76 mm / sec. Another dwell period of 12 sec was allowed to elapse. The DI water solution was sprayed onto the substrate while the stage moved vertically upward at 102 mm / sec. Finally, the substrate was then dried with an airknife at a speed of 3 mm / sec. The above sequence was repeated to deposit a number of “bi-layers” denoted as (Polycation / Polyanion)n where n is the number of bilayers.

[0098] Method for Reactive Ion Etching Microstructured Film

[0099] Reactive ion etching (RIE) was performed in a parallel plate capacitively coupled plasma reactor. The chamber has a central cylindrical powered electrode with a surface area of 18.3 ft2. After placing the microstructured film on the powered electrode, the reactor chamber was pumped down to a base pressure of less than 1.3 Pa (2 mTorr). A mixture of Ar (argon) and 02 (oxygen) gas was flowed into the chamber, each at a rate of 100 SCCM. Treatment was carried out using a plasma enhanced CVD method by coupling RF power into the reactor at a frequency of 13.56 MHz and an applied power of 6000 watts. Treatment time was controlled by moving the microstructured film through the reaction zone. Following the treatment, the RF power and the gas supply were stopped and the chamber was returned to atmospheric pressure. Additional information regarding materials, processes for applying cylindrical RIE, and further details around the reactor used can be found in U.S. Pat. No. 8,460,568 B2.

[0100] Method for Back-Filling Channels of the Microstructured Film

[0101] The channels were back-filled with Resin A used in PEI by pipetting the resin between the microstructured film surface and a piece of unprimed, 2 mil-thick PET film placed on top, using a hand roller to apply pressure to the top PET film, and then UV curing with a Heraeus (Hanau, Germany) belt conveyer UV processor (Model #DRS(6)) with an ‘H’ bulb at 500 Watt power.Specifically, the samples were sent through the UV curing station three times at a conveyer speed of 50 ft / min. Next, the top PET film was stripped off the microstructured film by hand.

[0102] Method for Measuring the Luminance Profile from a Diffuse Light Source

[0103] A sample of film was placed on a Lambertian light source. When the light transmissive regions are tapered, the film is positioned such that the widest portion of the tapered regions are closer to the light source. An Eldim L80 conoscope (Eldim S. A., HEROUVILLE SAINT CLAIR, France) was used to detect light output in a hemispheric fashion at all polar and azimuthal angles simultaneously. After detection, a cross section of transmission (e.g. brightness) readings were taken in a direction orthogonal to the direction of the louvers (denoted as a 0° orientation angle), unless indicated otherwise. Relative transmission (i.e. brightness of visible light) is defined as the percentage of on- axis luminance, at a certain viewing angle, between a reading with film and a reading without the film.

[0104] The Lambertian light source consisted of diffuse transmission from a light box having the baseline luminance profile depicted in FIG. 14. The light box was a six-sided hollow cube measuring approximately 12.5 cmxl2.5 cmxll.5 cm (LxWxH) made from diffuse polytetrafluoroethylene (PTFE) plates of 6 mm thickness. One face of the box was chosen as the sample surface. The hollow light box had a diffuse reflectance of~0.83 measured at the sample surface (e.g., 83%, averaged over the 400-700 nm wavelength range). During testing, the box was illuminated from within through a 1 cm circular hole in the bottom of the box (opposite the sample surface, with the light directed toward the sample surface from inside). The illumination was provided using a stabilized broadband incandescent light source attached to a fiber-optic bundle used to direct the light (Fostec DCR-H with a 1 cm diameter fiber bundle extension from Schott-Fostec LLC, Marlborough Mass, and Auburn, N.Y.).

[0105] Method for Cross-Sectional Scanning Electron Microscopy (SEM)

[0106] Cross-sections were prepared via freeze fracturing using liquid nitrogen. SEM images were acquired with a Hitachi SU-8230 (Hitachi, Ltd., Tokyo, Japan) instrument.

[0107] Preparative Example 2 (PE2): Preparation of Coating Solutions

[0108] PDAC was diluted from 20 wt % to a concentration of 0.32 wt % with deionized (DI) water. PAA was diluted from 25 wt % to a concentration of 0.1 wt %, and the pH was adjusted to 4.0 with IM NaOH. CAB-O-JET® 200 (COJ200), CAB-O-JET® 250C (COJ250C), CAB-O-JET® 260M (COJ260M), and CAB-O-JET® 352K (COJ352K) were each diluted to a concentration of 0.10 wt % with DI water. NaCl was added to both the PDAC solution and pigment suspensions to a concentration of 0.05 M. IM NaOH was added to the COJ352K suspension to a pH of 9. pH values were measured with a VWR (West Chester, PA) pH electrode (Catalog #89231-582), which was calibrated with standard buffer solutions.

[0109] Example 1

[0110] A sheet of microstructured film as made in PEI was cut to a size of 9"xl0" and corona treated by hand using a BD-20AC Laboratory Corona Treater (Electro-Technic Products, Chicago, IL) to prevent the aqueous coating solutions from beading up and dewetting. PDAC and CAB-O-JET® 200 coating solutions were made as described in PE2. The corona-treated film was coated with (PDAC / COJ200)10 using the “Method for Making Lay er-by -Layer Self- Assembled Coatings on Microstructured Film”. This coated film was subjected to reactive ion etching (RIE) at a power of 6000 W for a duration of 210s. After subjecting to the RIE, the substrate was laminated in a room temperature nip, with 500 lb . / linear inch (87.5 kN / m) of lamination force at 5 fpm (2.1 mm per second). The nip comprised two nominally 18" (-46 cm) smooth stainless steel rolls, one roll being undriven. This resulted in buckled microstructures that were backfilled within an hour.

[0111] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in theforegoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein.

[0112] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

1. CLAIMS:

1. A method of making an angled light control film (LCF) comprising:providing an LCF comprising alternating light transmissive regions and light absorbing regions disposed between a light input surface and a light output surface, wherein the light transmissive regions extend along a same in-plane first direction and arranged along an in-plane orthogonal second direction, each of the light transmissive regions having a top surface and sidewalls and each of the light absorbing regions having a bottom surface disposed between two adjacent light transmissive regions; andapplying a compressive force to at least one of the light input surface and the light output surface of the LCF along the second direction to obtain the angled LCF.

2. The method of claim 1, further comprising:providing a microstructured film comprising the light transmissive regions alternated with channels, wherein the microstructured film has a microstructured surface defined by the top surface and the sidewalls of the light transmissive regions and a channel bottom surface of the channels and a non-microstructured surface opposite to the microstructured surface; applying a light absorbing material to the microstructured surface;removing at least a portion of the light absorbing material from the top surface of the light transmissive regions and the channel bottom surface of the channels; andfilling the channels with a polymeric material to obtain the LCF.

3. The method of claim 1 further comprising:providing a microstructured film comprising the light transmissive regions alternated with channels, wherein the microstructured film has a microstructured surface defined by the plurality of light transmissive regions and the channels and a non-microstructured surface opposite to the microstructured surface; andfilling the channels of the microstructured film with a light absorbing material to obtain the LCF.

4. An angled light control film (LCF) comprising:a light input surface and a light output surface opposite the light input surface; and alternating light transmissive regions and light absorbing regions disposed between the light input surface and the light output surface, the light transmissive regions comprising first and second light transmissive regions, wherein the first light transmissive regions extend along a same in-plane first direction and arranged along an in-plane orthogonal second direction, each of the first light transmissive regions having a top surface and sidewalls and each of the secondlight transmissive region having a bottom surface disposed between two adjacent light absorbing regions and at least partially disposed on the top surface of an adjacent first light transmissive region, wherein each of the sidewalls is inclined at an inclination angle greater than about 2 degrees with respect to a normal from the bottom surface along the second direction, wherein the first light transmissive regions have a unitary construction, wherein each of the sidewalls comprises a first portion extending from the top surface and a second portion extending from the first portion to the bottom surface, and wherein the first portion is inclined at a first inclination angle and the second portion is inclined at a second inclination angle with respect to the normal from the bottom surface, the first inclination angle is greater than the second inclination angle.

5. An angled light control film (LCF) comprising:a light input surface and a light output surface opposite the light input surface; and alternating light transmissive regions and light absorbing regions disposed between the light input surface and the light output surface, the light transmissive regions comprising first and second light transmissive regions, wherein the first light transmissive regions extend along a same in-plane first direction and arranged along an in-plane orthogonal second direction, each of the first light transmissive regions having a top surface and sidewalls and each of the second light transmissive region having a bottom surface disposed between two adjacent light absorbing regions and at least partially disposed on the top surface of an adjacent first light transmissive region, wherein each of the sidewalls is inclined at an inclination angle greater than about 2 degrees with respect to a normal from the bottom surface along the second direction, and wherein the first light transmissive regions have a unitary construction.

6. The angled LCF of claim 5, wherein, in a plan view, the bottom surface of each of the second light transmissive regions is fully covered by the top surface of the adjacent first light transmissive region.

7. The angled LCF of claim 5, wherein the top surface of each of the first light transmissive regions is inclined with respect to the light output surface.

8. The angled LCF of claim 5, wherein the bottom surfaces of the second light transmissive regions substantially lie in a same plane which is substantially parallel to the light input surface.

9. The angled LCF of claim 5, wherein, in a sectional view along a third direction perpendicular to each of the first direction and the second direction, the top surfaces of the first light transmissive regions and lines joining the adjacent the top surfaces follow a zig-zag pattern extending along the second direction.

10. The angled LCF of claim 5, wherein a portion of each of the sidewalls extending from the top surface is curved.

11. The angled LCF of claim 10, wherein the curved portion is at most about 50% of the sidewall.

12. The angled LCF of claim 5, wherein each of the sidewalls comprises a first portion extending from the top surface and a second portion extending from the first portion to the bottom surface, and wherein the first portion is inclined at a first inclination angle and the second portion is inclined at a second inclination angle with respect to a normal from the bottom surface, the first inclination angle is greater than the second inclination angle.

13. The angled LCF of claim 5, wherein the angled LCF has an optical transmission, as measured with a conoscope for a wavelength range of between about 400 nm to about 700 nm, having a maximum transmission at a viewing angle of greater than about 2 degrees and less than about 30 degrees, and wherein the optical transmission has a full width at half maxima extending from a first viewing angle to a second viewing angle, a magnitude of the first viewing angle is greater than a magnitude of the second viewing angle by about 2 degrees.

14. A display system for use in a vehicle comprising:a display configured to form and emit an image for viewing by an eye of one or more occupants of the vehicle; andthe angled LCF of claim 5 disposed on the display, such that the light input surface faces the display and the light output surface faces the eye, the angled LCF configured to receive the emitted image and transmit an angled image toward the one or more occupants.

15. The display system of claim 14, wherein the eye of a first occupant of the one or more occupants of the vehicle is positioned in a first viewing space allowing the first occupant to view the angled image at a first brightness, and wherein the eye of a second occupant of the one or more occupants of the vehicle is positioned in a different second viewing space allowing the second occupant to view the angled image at a second brightness, and wherein a ratio of magnitudes of the first and second brightness is greater than about 1.25.

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