U.S. patent application number 13/095341 was filed with the patent office on 2011-08-18 for light directing film.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Todd M. Johnson, Patrick H. Marushin, Tetsuya Toma.
Application Number | 20110199557 13/095341 |
Document ID | / |
Family ID | 38789775 |
Filed Date | 2011-08-18 |
United States Patent
Application |
20110199557 |
Kind Code |
A1 |
Johnson; Todd M. ; et
al. |
August 18, 2011 |
LIGHT DIRECTING FILM
Abstract
A light directing film and an optical system incorporating same
are disclosed. The light directing film includes a first major
surface and a microstructured second major surface. The
microstructured second major surface has at least two periodic
microstructured patterns. The first periodic pattern is arranged
along a first direction. The second periodic pattern is arranged
along a second direction different from the first direction.
Inventors: |
Johnson; Todd M.; (St. Paul,
MN) ; Toma; Tetsuya; (Woodbury, MN) ;
Marushin; Patrick H.; (St. Paul, MN) |
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
38789775 |
Appl. No.: |
13/095341 |
Filed: |
April 27, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11421342 |
May 31, 2006 |
7950838 |
|
|
13095341 |
|
|
|
|
Current U.S.
Class: |
349/62 ;
359/599 |
Current CPC
Class: |
G02F 1/133504 20130101;
G02B 6/0053 20130101; G02B 5/045 20130101 |
Class at
Publication: |
349/62 ;
359/599 |
International
Class: |
G02F 1/13357 20060101
G02F001/13357; G02B 5/02 20060101 G02B005/02 |
Claims
1. A light directing film comprising a first major surface and a
second major surface, the second major surface having a
two-dimensional microstructured pattern superimposed on a
one-dimensional periodic microstructured pattern.
2. The light directing film of claim 1, wherein the two-dimensional
microstructured pattern is periodic along at least one
direction.
3. The light directing film of claim 1, wherein the two-dimensional
microstructured pattern is periodic along at least two different
directions.
4. The light directing film of claim 1, wherein each microstructure
in the one-dimensional and two-dimensional patterns has a peak and
a peak height measured from the peak to a common reference plane
disposed between the first and second major surfaces, and wherein
the heights of the microstructures in the one-dimensional periodic
microstructured pattern are different than the heights of the
microstructures in the two-dimensional microstructured pattern.
5. The light directing film of claim 4, wherein at least two
microstructures in the two-dimensional microstructured pattern have
different heights.
6. The light directing film of claim 1, wherein at least two
microstructures in the two-dimensional microstructured pattern have
different shapes.
7. The light directing film of claim 1, wherein the microstructures
in the one- and two-dimensional patterns extend along a same
direction.
8. The light directing film of claim 1, wherein at least some of
the microstructures in the one- and two-dimensional patterns are
prismatic.
9. A light guide assembly for use in a liquid crystal display, the
light guide assembly comprising at least one light directing film
of claim 1.
10. A light directing film comprising a first major surface and a
second major surface, the second major surface having a
two-dimensional regularly-spaced pattern of discrete elements
disposed on a one-dimensional periodic microstructured pattern.
11. The light directing film of claim 10, wherein at least some of
the discrete elements are microstructured.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. Ser. No. 11/421342,
filed on May 31, 2006, and published as U.S. Patent Application
Publication No. 2007/0279773, now allowed.
FIELD OF THE INVENTION
[0002] This invention generally relates to light directing films
and displays incorporating same. In particular, the invention
relates to light directing films having at least two periodic
microstructured patterns along different directions.
BACKGROUND
[0003] Liquid crystal displays (LCDs) often incorporate one or more
periodic microstructured films to enhance display brightness along
a pre-determined direction, typically, where a user is expected to
be located. The periodic microstructured film typically includes a
periodic array of linear prisms. In some applications, a single
prismatic film is used, while in others two crossed prismatic films
are employed, in which case, the two crossed prismatic films are
often oriented normal to each other.
[0004] The periodic pattern of a prismatic film employed in an LCD
can optically interfere with the periodic pattern of the pixelated
liquid crystal panel resulting in an undesirable moire pattern that
degrades a displayed image.
SUMMARY OF THE INVENTION
[0005] Generally, the present invention relates to light directing
films. The present invention also relates to light directing films
employed in display systems.
[0006] In some embodiments, a light directing film includes a first
major surface and a microstructured second major surface. The
microstructured second major surface has at least two periodic
microstructured patterns. The first periodic pattern is arranged
along a first direction and has a first period. The second periodic
pattern is arranged along a second direction and has a second
period. The second direction is different from the first
direction.
[0007] In some embodiments, a light directing film includes a first
major surface and a second major surface. The second major surface
has a two-dimensional microstructured pattern that is superimposed
on a one-dimensional periodic microstructured pattern.
[0008] In some embodiments, a light directing film includes a first
major surface and a second major surface. The second major surface
has a one-dimensional periodic microstructured pattern. The second
major surface further includes a two-dimensional regularly-spaced
pattern of discrete elements that are disposed on the
one-dimensional periodic microstructured pattern.
BRIEF DESCRIPTION OF DRAWINGS
[0009] The invention may be more completely understood and
appreciated in consideration of the following detailed description
of various embodiments of the invention in connection with the
accompanying drawings, in which like reference numbers designate
like parts, and wherein:
[0010] FIG. 1 is a three-dimensional schematic view of a
conventional light directing film;
[0011] FIG. 2 is a schematic side-view of a liquid crystal display
that includes a conventional light directing film;
[0012] FIG. 3 is a schematic top-view of a light directing
film;
[0013] FIGS. 4A and 4B are exemplary cross-sectional profiles of
light directing films;
[0014] FIGS. 5A-5C are exemplary cross-sectional profiles of light
directing films;
[0015] FIGS. 6A-6E are exemplary cross-sectional profiles of
microstructures;
[0016] FIG. 7 is a schematic top-view of a light directing film in
accordance with one embodiment of the invention;
[0017] FIG. 8 is a three-dimensional schematic view of another
light directing film;
[0018] FIG. 9 is a schematic top-view of a light directing
film;
[0019] FIGS. 9A and 9B are exemplary cross-sectional profiles of
light directing films;
[0020] FIG. 10 is a schematic top-view of a light directing
film;
[0021] FIG. 11 is a schematic top-view of a light directing
film;
[0022] FIG. 12 is a schematic side-view of a light guide assembly;
and
[0023] FIG. 13 is a schematic side-view of an illumination
assembly.
DETAILED DESCRIPTION
[0024] The present invention generally relates to light directing
films that include two or more periodic microstructured patterns.
The invention is further applicable to liquid crystal displays
employing at least one light directing film where it is desirable
to reduce or minimize moire effects that can result from optical
interference between the periodic patterns of the light directing
film and the liquid crystal panel, and/or where it is desirable to
minimize optical coupling between the light directing film and a
planar optical film that may be located in close proximity to the
light directing film.
[0025] FIG. 1 is a schematic three-dimensional view of a
conventional prismatic light directing film 100. Films similar to
film 100 have been previously disclosed, for example, in U.S. Pat.
Nos. 4,906,070 (Cobb) and 5,056,892 (Cobb). Film 100 has a first
major surface 110 and a microstructured second major surface 120.
Film 100 further includes a plurality of linear prisms 115 each of
which has two side surfaces, such as surfaces 161, 162, and 163,
and extends linearly along the z-axis. Film 100 has a prismatic
cross-section in the xy-plane. Film 100 further has a plurality of
peaks 101 and grooves 102. Peaks 101 have a same height as measured
from a common reference plane, such as plane 125 or 126, placed
somewhere between first and second major surfaces 110 and 120,
respectively. For an equal height prism structure, the peaks of all
the linear prisms lie in a same plane, meaning that a planar film
130 brought into contact with light directing film 100, contacts
all the peaks of the linear prisms of film 100.
[0026] The operation of conventional light directing film 100 has
been previously described, for example, in U.S. Pat. No. 5,056,892
(Cobb). In summary, a light ray, such as ray 131, that strikes
surfaces 161 or 162 at incident angles larger than the critical
angle are totally internally reflected back. On the other hand, a
light ray, such as ray 132 that is incident on a side surface, such
as surface 163, at angles less than the critical angle is partly
transmitted (such as ray 132a) and partly reflected (such as ray
132b). An end result is that when employed in a display, such as a
liquid crystal display, light directing film 100 can result in
display brightness enhancement by redirecting light and by
recycling light that is totally internally reflected.
[0027] FIG. 2 is a schematic side-view of a liquid crystal display
295 that includes a conventional light directing film. For ease of
illustration and without loss of generality, FIG. 2 only shows a
few exemplary components in a typical liquid crystal display. In
particular, liquid crystal display 295 includes a liquid crystal
panel 291, light directing film 100, and a light guide 290. Light
directing film 100 has a periodic pattern 294 with pitch
T.sub.1.
[0028] Liquid crystal panel 291 includes a periodic pattern 292 due
to, for example, liquid crystal pixels and/or color filter
patterning. Periodic pattern 292 is disposed between components 297
and 298, where components 297 and 298 can, for example, be glass
sheets. Liquid crystal panel 291 typically includes other
components, not shown in FIG. 2, such as thin film transistors,
transparent conductive electrodes, and polarizers. The periodic
pattern 292 has a pitch T.sub.2.
[0029] The overlapping of periodic patterns 292 and 294 results in
a moire pattern that is essentially an interference pattern between
the two periodic patterns. Although the moire effect has many
practical uses such as in metrology, the effect can be undesirable
in other applications particularly in liquid crystal displays where
the moire pattern can interfere with easy viewing of a displayed
image and reduce resolution, contrast, and in general, quality of
the image. As described below in detail, the present application
discloses light directing films that have multiple periodic
patterns resulting in multiple moire patterns with the aggregate
pattern being less visible.
[0030] FIG. 3 is a schematic top-view of an exemplary light
directing film 200. Light directing film 200 has a major
microstructured surface 205 that has at least two periodic
microstructured patterns. In particular, major surface 205 includes
a periodic microstructured pattern 210 arranged along direction 211
with a period P1, where direction 211 is along the x-axis.
Exemplary microstructures included in periodic microstructured
pattern 210 are microstructures 210A, 210B, 210C, and 210D. Major
surface 205 further includes a periodic microstructured pattern 220
arranged along direction 221 with a period P2, where direction 221
is different from direction 211. Exemplary microstructures included
in periodic microstructured pattern 220 are microstructures 220A,
220B, 220C, and 220D. In some applications, periods P1 and P2 are
different. In some other applications, the two periods are
equal.
[0031] Period P1 can, in general, be any value. In some
applications, period P1 is in a range from about 1,000 microns to
about 10,000 microns. In some other applications, P1 is in a range
from about 1 micron to about 200 microns. In some other
applications, P1 is in a range from about 10 microns to about 100
microns.
[0032] Major surface 205 further includes a periodic
microstructured pattern 230 arranged along direction 231 with a
period P3, where direction 231 is different from directions 211 and
221. An exemplary microstructure included in periodic
microstructured pattern 230 is microstructure 230A . In some
applications, periods P1, P2, and P3 are different. In some other
applications, some of the periods in the periodic patterns may be
equal and some other periods may be different.
[0033] In the exemplary embodiment shown in FIG. 3, a
microstructure may be included in more than one periodic pattern.
For example, microstructure 220D is included in both periodic
patterns 220 and 230. It can readily be appreciated from FIG. 3
that major microstructured surface 205 includes other periodic
patterns not explicitly described herein.
[0034] Microstructured major surface 205 can also be described as
having a two-dimensional microstructured pattern 280 superimposed
on a one-dimensional periodic microstructured pattern 210. In the
exemplary embodiment shown in FIG. 3, the two-dimensional
microstructured pattern is periodic along at least one direction,
such as directions 221 and 231. In general, pattern 280 can be
aperiodic. In some applications, pattern 280 can have a chirped
periodicity along a direction, meaning that the period changes in a
predetermined way, for example linearly, along the direction.
[0035] In the embodiment of FIG. 3, the two-dimensional
microstructured pattern 280 is periodic and includes a
two-dimensional array of regularly spaced microstructures such as
microstructures 220A, 220D, 230A, and 280A arranged in the
xz-plane. The one-dimensional periodic pattern 210 includes a
linear array of regularly spaced microstructures such as
microstructures 210A and 210D arranged in the xz-plane.
[0036] FIG. 4A illustrates a schematic cross-sectional view of
light directing film 200, in particular of microstructures 220C and
210B, where the cross-section is taken along direction XX' in FIG.
3. Light directing film 200 has a major surface 206 and a
microstructured major surface 205. Each microstructure in major
surface 205 of light directing film 200 has a peak and a peak
height measured from the peak to a common reference plane 285
disposed between major surfaces 205 and 206. For example,
microstructure 210B has a peak 210B1 and an associated peak height
210B2. Similarly, microstructure 220C has a peak 220C1 and an
associated peak height 220C2. In general, peak heights of
microstructures in different periodic patterns may or may not be
equal. For example, in the exemplary embodiment shown in FIG. 4A,
peak height 220C2 is greater than peak height 210B2. In the
exemplary embodiment shown in FIG. 4B, peak height 220C2 is smaller
than peak height 210B2.
[0037] In general, peak heights 220C2 and 210B2 can be any value.
In some applications, peak heights 220C2 and 210B2 are no greater
than 1,000 microns, where for the purposes of discussing peak
heights, common reference plane 285 is chosen as the plane closest
to structured surface 205, such as plane 285A. In some
applications, peak heights 220C2 and 210B2 are no greater than 100
microns, or no greater than 50 microns.
[0038] In general, the difference between peak heights 220C2 and
210B2 can be any value. In some applications, the difference
between peak heights 220C2 and 210B2 is no greater than 1,000
microns. In some applications, the difference is no greater than
100 microns, or no greater than 10 microns.
[0039] FIG. 5A illustrates a schematic cross-sectional view of
light directing film 200, in particular, of microstructures 220C,
210C, and 210D where the cross-section is taken along direction YY'
in FIG. 3. Prismatic microstructure 220C is part of the periodic
pattern 220 shown in FIG. 3 and prismatic microstructures 210C and
210D are part of the periodic pattern 210 shown in FIG. 3.
Microstructure 220C has a peak 220C1 and a peak height 220C2
relative to common reference plane 285. Similarly, microstructure
210C has a peak 210C1 and an associated peak height 210C2 where
peak height 220C2 is greater than peak height 210C2. In the
exemplary embodiment shown in FIG. 5B, structure 220C has two peaks
220C1 each having peak height 220C2 where peak height 220C2 is
smaller than peak height 210C2.
[0040] In the exemplary embodiments shown in FIGS. 5A and 5B,
microstructure 220C partially modifies microstructure 210B across
the length of microstructure 220C along the z-axis. In the
exemplary embodiment shown in FIG. 5C, microstructure 220C
effectively replaces microstructure 210B along the length of
microstructure 220C.
[0041] In the exemplary embodiments shown in FIGS. 5A-5C,
microstructure 220C is symmetrically positioned relative to
microstructures 210C and 210D. In general, microstructures of
pattern 280 can be placed anywhere on major surface 205. In
particular, in some applications, two-dimensional microstructured
pattern 280 can be positioned asymmetrically relative to
one-dimensional periodic microstructured pattern 210.
[0042] The exemplary microstructures shown in FIG. 5A are prismatic
having triangular profiles. In general, light directing film 200
can include any shape microstructure that is capable of directing
light. Exemplary microstructures having different profiles are
shown in FIGS. 6A-6E. In FIG. 6A, extended prisms 1800A have
straight sides 1810A, sharp peaks 1820A, sharp grooves, and peak
angle .alpha..sub.A, similar to the prisms of FIG. 5A. Prisms 1800B
in FIG. 6B have straight sides 1810B, round peaks 1820B, round
grooves, and peak angles .alpha..sub.B. The radius of curvature of
the peak or the groove can, for example, be in the range from about
1 to 100 microns. In FIG. 6C, prisms 1800C have straight sides
1810C, flat peaks 1820C, sharp grooves, and peak angle
.alpha..sub.C. As a further example, prisms 1800D in FIG. 6D have
curved sides 1810D, sharp peaks 1820D, round grooves, and peak
angle .alpha..sub.D. As yet another example, prisms 1800E in FIG.
6E have piece-wise linear sides 1810E, sharp peaks 1820E, sharp
grooves, and peak angle .alpha..sub.E.
[0043] FIG. 7 is a schematic top-view of another light directing
film 500. Light directing film 500 has a microstructured major
surface 505 that has at least two periodic microstructured
patterns. In particular, major surface 505 includes a periodic
microstructured pattern 510 arranged along direction 511 with a
period Q1, where direction 511 is along the x-axis. Exemplary
microstructures included in periodic microstructured pattern 510
are microstructures 510A, 510B, 510C, 510D, and 510E. Major surface
505 further includes a periodic microstructured pattern 520
arranged along direction 521 with a period Q2, where direction 521
is different from direction 511. Exemplary microstructures included
in periodic microstructured pattern 520 are microstructures 520A,
520B, and 520C. In some applications, periods Q1 and Q2 are
different. In some other applications, Q1 and Q2 are equal.
[0044] Major surface 505 further includes a periodic
microstructured pattern 530 arranged along direction 531 where
direction 531 is parallel to direction 521. Exemplary
microstructures included in periodic microstructured pattern 530
are microstructures 530A and 530B. Major surface 505 further
includes a periodic microstructured pattern 540 arranged along
direction 541 where direction 541 is parallel to directions 521 and
531. Exemplary microstructures included in periodic microstructured
pattern 540 are microstructures 540A and 540B.
[0045] Microstructured major surface 505 can be viewed as having a
two-dimensional microstructured pattern 580 superimposed on a
one-dimensional periodic microstructured pattern 510. The
two-dimensional microstructured pattern 580 is periodic and
includes a two-dimensional array of regularly spaced
microstructures such as microstructures 520A, 530A, and 540A
arranged in the xz-plane. The one-dimensional periodic pattern 510
includes a linear array of regularly spaced microstructures such as
microstructures 510A and 510E arranged in the xz-plane.
[0046] FIG. 8 is a schematic three-dimensional view of a portion of
light directing film 500 of FIG. 7. In particular, FIG. 8 shows
prismatic microstructures 510C, 510D, and 510E that are included in
periodic pattern 510 and are linearly extended along the z-axis.
FIG. 8 also shows microstructures 520A, 520B, and 520C that are
included in periodic pattern 520 or two-dimensional periodic
pattern 580 where pattern 580 is superimposed on pattern 510.
[0047] In the exemplary embodiment shown in FIG. 8, the
microstructures belonging to periodic pattern 580 are taller than
the microstructures belonging to periodic pattern 510. In some
applications, the microstructures belonging to periodic pattern 580
are shorter than the microstructures belonging to periodic pattern
510.
[0048] Furthermore, in the exemplary embodiment shown in FIG. 8,
the height of a microstructure is constant. In general, the height
of a microstructure can vary with position, for example, with
position along the z-axis. For example, the height of
microstructure 510C can vary along the z-axis even in areas where
microstructure 510 C is not superimposed by another microstructure
such as microstructure 520A.
[0049] FIG. 9 is a schematic top-view of another light directing
film 700. Light directing film 700 has a microstructured major
surface 705 that includes a two-dimensional microstructured pattern
780 superimposed on a one-dimensional periodic microstructured
pattern 710. In some embodiments, two-dimensional microstructured
pattern 780 is periodic along at least one direction, such as
direction 721. In some applications, two-dimensional
microstructured pattern 780 is periodic along at least two
different directions, such as directions 721 and 731.
[0050] In the exemplary embodiment shown in FIG. 9, two-dimensional
periodic microstructured pattern 780 includes a two-dimensional
array of regularly-spaced microstructures such as microstructures
720A and 730A arranged in the xz-plane. The one-dimensional
periodic pattern 710 includes a linear array of regularly spaced
microstructures, such as microstructures 710A and 710B, that are
arranged in the xz-plane along direction 711 with each linear
microstructure extending along the z-axis.
[0051] The two-dimensional periodic microstructured pattern 780
includes a plurality of periodic patterns, where each pattern is
arranged along a direction. For example, two-dimensional periodic
microstructured pattern 780 includes a periodic microstructured
pattern 720 arranged along direction 721 where direction 721 is
different from direction 711. An exemplary microstructure included
in periodic microstructured pattern 720 is microstructure 720A. As
another example, two-dimensional periodic microstructured pattern
780 includes a periodic microstructured pattern 730 arranged along
direction 731 where direction 731 is parallel to direction 711. An
exemplary microstructure included in periodic microstructured
pattern 730 is microstructure 730A.
[0052] Each microstructure in the one-dimensional periodic pattern
710 and two-dimensional pattern 780 has a peak and an associated
peak height. In some cases, the heights of the microstructures in
the one-dimensional periodic microstructured pattern are different
than the heights of the microstructures in the two-dimensional
microstructured pattern. In some cases, at least two
microstructures in two-dimensional microstructured pattern 780 have
different heights.
[0053] The microstructures in two-dimensional microstructured
pattern 780 may or may not have the same shape. In some cases, at
least two microstructures in the two-dimensional microstructured
pattern have different shapes. For example, microstructure 720A can
have a rectangular cross-sectional profile in the xy-plane and
microstructure 730A can have a triangular cross-sectional profile
in the xy-plane.
[0054] FIG. 9 illustrates a light directing film 700 having a first
major surface 704 (see FIG. 9A) and a second major surface 705.
Second major surface 705 includes a one-dimensional periodic
microstructured pattern 710. Second major surface 705 further
includes a two-dimensional regularly-spaced pattern of discrete
elements, such as discrete elements 720A and 730A, disposed on the
one-dimensional periodic microstructured pattern 710. The discrete
elements can be formed on pattern 710 by, for example, screen
printing, ink-jet printing, photolithography, or any other method
that may be appropriate for forming the two-dimensional array of
discrete elements 780 on pattern 710.
[0055] FIG. 9A illustrates a schematic cross-sectional view of
light directing film 700 along direction 731 in the xy-plane. In
particular, FIG. 9A shows discrete element 730A from the
two-dimensional array of discrete elements 780 disposed on
prismatic microstructure 710C from the one-dimensional periodic
microstructured pattern 710. Element 730A can be a coating
conformally formed on microstructure 710C by, for example, ink jet
printing. In the exemplary embodiment shown in FIG. 9A, element
730A covers the top or peak of microstructure 710C. In general,
element 730A can be formed any where on microstructure 710C, such
as on a side of microstructure 710C as shown schematically in FIG.
9B.
[0056] FIG. 10 is a schematic top view of another light directing
film 800. Light directing film 800 has a microstructured major
surface 805 that includes a two-dimensional periodic
microstructured pattern 820 superimposed on a one-dimensional
periodic microstructured pattern 810. The two-dimensional periodic
microstructured pattern 820 includes a two-dimensional array of
regularly-spaced microstructures, such as microstructures 820A and
820B, arranged in the xz-plane. The one-dimensional periodic
pattern 810 has a period R1 and includes a linear array of
regularly-spaced microstructures, such as microstructures 810A and
810B, that are arranged in the xz-plane along direction 811 with
each linear microstructure extending along the z-axis.
[0057] The two-dimensional periodic microstructured pattern 820
includes a plurality of periodic patterns, where each pattern is
arranged along a direction. For example, two-dimensional periodic
microstructured pattern 820 includes a periodic microstructured
pattern 840 arranged along direction 821 with a period R2 where
direction 821 is different from direction 811. Exemplary
microstructures included in periodic microstructured pattern 840
are microstructures 840A and 840B. As another example,
two-dimensional periodic microstructured pattern 820 includes a
periodic microstructured pattern 850 arranged along direction 822
with period R3 where direction 822 is different from directions 811
and 821.
[0058] FIG. 11 is a schematic top-view of another light directing
film 900. Light directing film 900 has a microstructured major
surface 905 that includes a two-dimensional microstructured pattern
920 superimposed on a one-dimensional periodic microstructured
pattern 910. The two-dimensional microstructured pattern 920
includes a two-dimensional array of microstructures, such as
microstructures 920A and 920B, arranged in the xz-plane. The
one-dimensional periodic pattern 910 has a period Si and includes a
linear array of regularly-spaced microstructures, such as
microstructures 910A and 910B, that are arranged in the xz-plane
along direction 911 with each linear microstructure extending along
the z-axis.
[0059] The two-dimensional microstructured pattern 920 includes one
or more periodic microstructured patterns, where each pattern is
arranged along a direction. For example, two-dimensional
microstructured pattern 920 includes a periodic microstructured
pattern 930 arranged along direction 931 with a period S2 where
direction 931 is different from direction 911. As another example,
two-dimensional periodic microstructured pattern 920 includes a
periodic microstructured pattern 940 arranged along direction 941
with period S3 where direction 941 is different from directions 931
and 911. As yet another example, two-dimensional microstructured
pattern 920 includes a periodic microstructured pattern 950
arranged along direction 951 with a period S4 where direction 951
is parallel to direction 911.
[0060] FIG. 12 shows a schematic side-view of another light guide
assembly 1200. Light guide assembly 1200 can be used in any liquid
crystal device for displaying information. Light guide assembly
1200 includes a light source 1210, a light guide 1220, and a light
directing film 1230 where light directing film 1230 is a light
directing film according to any of the disclosed embodiments.
Although microstructured surface 1240 of film 1230 in FIG. 12 is
shown to face away from light guide 1220, in some applications,
microstructured surface 1240 can face light guide 1220. Light guide
assembly 1200 can further include an optional film 1250, similar to
film 1240, but oriented differently. For example, direction of
extended prisms in films 1250 and 1240 can be orthogonal to one
another. Light guide assembly 1200 can further include additional
films or components not explicitly shown in FIG. 12, such as
reflectors, diffusers such as diffuser plates, reflective
polarizers, protective films, mounting frames, or shading frames
such as masks.
[0061] FIG. 13 shows a schematic side-view of an illumination
assembly 1300. Illumination assembly 1300 can, for example, be used
in any liquid crystal device for displaying information, such as an
LCD television. Illumination assembly 1300 includes a back
reflector 1320, a diffuser sheet or plate 1330, and a plurality of
light sources 1310 positioned between back reflector 1320 and
diffuser 1330. Back reflector 1320 may be a diffuse reflector.
[0062] All patents, patent applications, and other publications
cited above are incorporated by reference into this document as if
reproduced in full. While specific examples of the invention are
described in detail above to facilitate explanation of various
aspects of the invention, it should be understood that the
intention is not to limit the invention to the specifics of the
examples. Rather, the intention is to cover all modifications,
embodiments, and alternatives falling within the spirit and scope
of the invention as defined by the appended claims.
* * * * *