U.S. patent application number 10/140042 was filed with the patent office on 2003-11-13 for micro lens systems and articles thereof.
Invention is credited to Huang, Pin Chien.
Application Number | 20030210466 10/140042 |
Document ID | / |
Family ID | 29399378 |
Filed Date | 2003-11-13 |
United States Patent
Application |
20030210466 |
Kind Code |
A1 |
Huang, Pin Chien |
November 13, 2003 |
MICRO LENS SYSTEMS AND ARTICLES THEREOF
Abstract
Micro lens systems and articles thereof that may be applied to
LCD display systems and/or projection systems include carrier media
layers having attached arrays of micro lens systems for
modification of a light path, either horizontally and/or
vertically. The micro lens systems may have light dispersing
surfaces and/or may contain an isotropic light disperser, such as
light diffusing particles or other types of bulk diffuser. The
carrier media layers may include combinations of reflective
material, highly transparent material, light absorbing material,
opaque material, photosensitive film, light dispersing material,
metallic material, prism-like optical material, retarding material,
polarizing material and/or any other functional material to provide
extra modification of optical performance. In addition, the carrier
media layers may each take the form of a film, plate, sheet, or any
other suitable structure with an appropriate thickness, and may be
formed with transparent apertures arrays or an opaque plastic or
metallic material having grids of perforations, such that light
pass through the apertures in the carrier media layers with no
modification. Finally, the carrier media layers may be attached to
each other or other supporting materials so as to provide a more
rigid structure strength.
Inventors: |
Huang, Pin Chien; (Taipei,
TW) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE
FOURTH FLOOR
ALEXANDRIA
VA
22314
|
Family ID: |
29399378 |
Appl. No.: |
10/140042 |
Filed: |
May 8, 2002 |
Current U.S.
Class: |
359/619 |
Current CPC
Class: |
G02B 3/0075 20130101;
G02B 3/0025 20130101; G02B 3/0031 20130101; G02B 3/0056
20130101 |
Class at
Publication: |
359/619 |
International
Class: |
G02B 027/10 |
Claims
What is claimed is:
1. Light controlling composite structures, comprising: micro lens
systems and at least one carrier media layer suitable for carrying
the micro lens systems; wherein said plurality of optical micro
lens systems are formed in molding tools, said plurality of optical
micro lens systems having predetermined physical and optical
characteristics, and wherein said optical micro lens systems are
attached to said carrier media layers, and wherein said plurality
of optical micro lens systems control paths of light incident on
said optical micro lens systems in accordance with said optical and
physical characteristics such that fields of light are
provided.
2. Articles including a light control composite structure,
comprising: micro lens systems and at least one carrier media layer
suitable for carrying the micro lens systems; wherein said
plurality of optical micro lens systems are formed in molding
tools, said plurality of optical micro lens systems having
predetermined physical and optical characteristics, and wherein
said optical micro lens systems are attached to said carrier media
layers, and wherein said plurality of optical micro lens systems
control paths of light incident on said optical micro lens systems
in accordance with said optical and physical characteristics such
that fields of light are provided.
3. An article according to claim 2, wherein said optical micro lens
systems together with said carrier media layers are provided with
reflective layer of materials and wherein said light control
material operates in reflective mode.
4. An article according to claim 2, wherein said optical micro lens
systems together with carrier media layers operate in transmissive
mode.
5. An article according to claim 2, wherein said physical
characteristics include index of refraction, radius, size, array
pitch, profile property, optical axis inclination and degree of
symmetry.
6. An article according to claim 2, wherein said optical micro lens
systems include rims of various physical characteristics, and said
carrier media layer includes a corresponding rim at each of the
locations on which micro lens systems are to be mounted, said rims
being adhered together when attaching the micro lens systems to the
carrier media layers.
7. An article according to claim 2, wherein at least one of said
micro lens systems has optical and physical characteristics that
are different than those of others of said plurality of micro lens
systems.
8. An article according to claim 2, wherein said micro lens systems
contain an isotropic light disperser, such as light diffusing
particles or other types of bulk diffuser.
9. An article according to claim 2, wherein said micro lens systems
include light dispersing surfaces.
10. An article according to claim 2, wherein the micro lens systems
are arranged in periodic arrays.
11. An article according to claim 2, wherein the micro lens systems
are arranged in random, non-periodic arrays.
12. An article according to claim 2, wherein said micro lens
systems are symmetric in shape.
13. An article according to claim 2, wherein said micro lens
systems are asymmetric in shape.
14. An article according to claim 2, wherein said micro lens
systems are concave with respect to a base image source.
15. An article according to claim 2, wherein said micro lens
systems are concave-concave lens systems.
16. An article according to claim 2, wherein the said micro lens
systems are convex with respect to a base image source.
17. An article according to claim 2, wherein said micro lens
systems are convex-convex lens systems.
18. An article according to claim 2, wherein the said micro lens
systems are convex-concave lens systems.
19. An article according to claim 2, wherein said carrier media
layer is a composite film, plate, or sheet, or attached to other
supporting structures so as to have greater rigidity.
20. An article according to claim 2, wherein said carrier media
layer is formed with an array of transparent apertures made up of
an opaque material having a grid of perforations, wherein light
passes through the carrier media layer apertures with no
modification.
21. An article according to claim 2, further comprising at least
one additional micro lens systems having optical and physical
characteristics which are different from the optical and physical
characteristics of said plurality of micro lens systems and said
carrier media layer, and wherein said at least one micro lens
system is arranged to provide a field of view which is different
from the field of view provided by said plurality of micro lens
systems and said carrier media layer.
22. A light control composite structure according to claim 21,
wherein said at least one additional micro lens system is symmetric
in shape.
23. A light control composite structure according to claim 21,
wherein said at least one additional micro lens systems is
asymmetric in shape and said plurality of micro lens systems are
symmetric in shape.
24. A light control composite structure according to claim 21,
wherein said at least one additional micro lens system is
asymmetric in shape.
25. A light control composite structure according to claim 21,
wherein said at least one additional micro lens system is symmetric
in shape and said plurality of micro lens systems are asymmetric in
shape.
26. An article according to claim 2, wherein arrays of said
plurality of optical micro lens systems with said optical and
physical characteristics are positioned at a surface of one side of
said carrier media layer.
27. An article according to claim 2, wherein separated arrays of
said plurality of optical micro lens systems with separate optical
and physical characteristics are positioned at surfaces of both
sides of said at least one carrier media layer.
28. An article according to claim 2, wherein two arrays of said
plurality of micro lens systems are positioned relative to two said
carrier media layers so that each surface of each said carrier
media layer that does not have said micro lens systems is attached
together.
29. An article according to claim 2, wherein arrays of said micro
lens systems are attached to said at least one carrier media layer
at one side of a supporting material.
30. An article according to claim 2, wherein separate arrays of
said plurality of optical micro lens systems are attached to
respective said carrier media layers and positioned at a front
surface and a back surface of a supporting materials.
31. An article according to claim 2, wherein said micro lens
systems are formed with said at least one carrier layer and highly
reflective layers of materials backing said micro lens systems and
carrier media layer, thereby making said micro lens systems and
articles thereof reflective, wherein said plurality of micro lens
systems reflect and control the paths of light incident on said
micro lens systems.
32. An article according to claim 2, wherein said plurality of
micro lens systems are formed with said at least one carrier media
layer and reflective layers of materials covering said micro lens
systems, thereby making said micro lens systems and articles
thereof reflective, wherein said plurality of micro lens systems
reflect and control the paths of light incident on said micro lens
systems.
33. An article according to claim 1, said at least one carrier
layers comprises composites selected from at least one layer of the
group consisting of a reflective layer, an opaque layer, a
transparent layer, a metallic layer, a photosensitive layer, a
light absorbing layer, a polarizing layer, a retarding layer, a
light dispersing layer, and a prism-like optical layer.
34. An article according to claim 1, wherein an image light source
transmits light polarized in a first polarization direction and
said at least one carrier layer further includes a polarizing layer
arranged to transmit light having another polarization direction.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field-of-the-Invention
[0002] This invention relates to light controlling composite
structures for enhancing the image quality of LCD displays,
projection systems, and the like. The composite structures include
micro lens arrays and carrier layers having optical properties.
[0003] 2. Description of Related Art
[0004] The display of images, no matter whether static or dynamic,
is of great importance to our everyday life. Portable electronic
equipment and other electronic equipment having low power
consumption display devices are now becoming a basic necessity.
[0005] Liquid Crystal Display (LCD) are one of the major
technologies used in these display devices. The LCD is a passive
device that cannot emit light. External lighting is necessary to
use a LCD device. For many applications of the LCD device,
batteries are used as the application's only power source.
[0006] As a result, a better LCD system design needs to consider
how to increase the light utilization efficiency. As indicated in
FIGS. 24 and 25, a variety of optical materials and structures are
typically used in order to improve the overall optical performance
of an LCD display device. Nevertheless, there is a clear need for
additional structures and materials that can enhance the light
utilization efficiency of many of the LCD applications.
[0007] Another technology that has made great progress in recent
years is the image projector. There are a variety of projector
types depending on the device that is used to form the image. Some
of the most recent developments include DMD (Digital Mirror Device,
from Texas Instruments) projectors and LCD projectors. However, the
final images from these projectors have to be displayed to the
viewer via some kind of media. The display media usually have a
large influence on the quality of the image a viewer sees, as do
the final media that "process or touch" the image. Usually, a
screen is used in such a setting. Depending on the viewer's
environment and the projection principle used, the screen can
either be a "front projection" or "rear projection" type. FIG. 26
indicates one of the prior art designs that provides a rear
projection screen using a sheet of polymer material that forms a
plurality of lenses to modify the light path. FIG. 27 is a typical
rear projection screen of the prior art, wherein a single layer of
optical beads is used to enhance the optical performance of the
rear projection screen. FIG. 28 is yet another prior art design
that uses a polymer material similar to that of FIG. 26 while
providing a different lens structure for optical path
modification.
[0008] The requirements for projection display devices used for
each application are different. For home entertainment, the user's
position in front of the display is likely to vary more in a
horizontal than a vertical direction. For display devices used in a
more public area, like a control room, an even wider horizontal
spread is commonly encountered.
[0009] In general, it is desirable that a projection screen be
capable of high resolution, high contrast, large gain and large
viewing angle. But it is difficult to meet all these requirements
simultaneously. For instance, the screen gain is often compromised
when a larger viewing angle is requested. Tradeoffs are usually
made in screen performance for each different application.
[0010] There is a need for improving the overall performance while
meeting the minimum performance criteria necessary for the
projection display application in which the screen is used, and in
general to improve the image quality for these applications.
[0011] By way of background, conventional LCD and projector
structures are shown in U.S. Pat. Nos. 4,666,248; 5,040,883;
5,467,417; 5,563,738; 5,917,664; and 6,317,263.
SUMMARY OF THE INVENTION
[0012] This invention relates generally to micro lens systems and
articles thereof, and more generally, to micro lens systems and
articles that may be applied to display devices suitable for use in
LCD display systems and/or projection systems.
[0013] One article embodying the present invention includes carrier
media layers having attached arrays of micro lens systems for
modification of the light path, either horizontally and/or
vertically.
[0014] The micro lens systems may have light dispersing surfaces
and/or may contain an isotropic light disperser, such as light
diffusing particles or other types of bulk diffuser. In either
case, dispersion may be such that the direction of maximum light
intensity is parallel to or at an angle relative to an axis normal
to the carrier media's major surface.
[0015] The carrier media layers of the composite structure may
include combinations of reflective material, highly transparent
material, light absorbing material, opaque material, photosensitive
film, light dispersing material, metallic material, prism-like
optical material, retarding material, polarizing material and/or
any other functional material to provide extra modification of
optical performance. In addition, the carrier media layers may each
take the form of a film, plate, sheet, or any other suitable
structure with an appropriate thickness, and may be formed with
transparent apertures arrays or an opaque plastic or metallic
material having grids of perforations, such that light pass through
the apertures in the carrier media layers with no modification.
Finally, the carrier media layers may be attached to each other or
other supporting materials so as to provide a more rigid structure
strength.
[0016] A number of micro machining technologies are now widely used
to form miniature electrical, mechanical and optical devices and
composite systems of these devices. Many new devices, such as micro
motors and micro gears made by these micro machining technologies
are now a well defined practice. One of the best known applications
of this technology is the digital micro mirror device from Texas
Instruments. This device now plays a key role in improvements to
image projectors.
[0017] Miniature optical elements such as micro lenses can also be
made, by the use of different technical tools, with good precision.
Well known technologies, such as laser ablation, photolithography,
chemical etching, electroforming and electrochemical machining,
etc., can be applied during the formation of the basic molding
tools for the micro lens systems.
[0018] After the molding tool is formed, polymer or copolymer
materials including, but not limited to, materials such as methyl
methacrylate, hydroxyethyl methacrylate, polystyrene,
polycarbonate, polyolefin, styrene, silicone hydrogel, siloxane,
etc. or any other suitable compositions, mixed with
photo-polymerization or other suitable polymerization initiator,
mold release agent and/or any other suitable additives (for
anti-static, anti-scratch, . . . ), can then be dispensed in
precise quantities into the molding tool. The adding of the
optional dispersion materials can be done during the material
mixing stage.
[0019] Soon after the micro lens materials are dispensed into the
molding tool, a suitable curing process is used to cure the
polymer. Depending on the choice of materials, the cured polymer
can have different indexes of refraction. The steps can be
repeated, manipulating the material types, material properties
(surface tension and affinities) and process steps to form the
various micro lens systems. The resulting micro lens systems may
have different optical performance.
[0020] Once the micro lens systems are formed with the present
invention, the micro lens systems and articles thereof can be used
to facilitate the optical functions they are designed for. One such
article uses these micro lens systems to shape the light path to
improve the system performance of display devices.
[0021] The carrier media layers, which may be combinations of a
reflective material, a plain transparent material, a opaque
material, a metallic material, a light absorbing material, a light
dispersing material or other desirable functional materials, are
attached to the micro lens systems via adhesive materials or by
other suitable fusing method. The functional materials can have any
of the following optical properties: light dispersing, light
polarizing, or anti-glare properties, or combinations of such
properties.
[0022] If holes are provide in the carrier media layers, the holes
may be formed with precisely controlled diameters during the
formation of the carrier media layers, or via a mechanical punch or
laser zapping. Along the surface of the carrier media layers there
can also be alignment marks (holes) made at precisely controlled
positions to facilitate alignment with the micro lens systems. Once
the carrier media layers are prepared according to the desired
process, suitable adhesive materials can also be pre-coated onto
the carrier media layers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIGS. 1A and 1B show a top and a cross sectional view of a
micro lens system and a molding tool for use in forming the micro
lens system in accordance with the principles of a preferred
embodiment of the invention.
[0024] FIGS. 2A and 2B show a top and a cross sectional view of
another micro lens system and molding tool therefor constructed in
accordance with the principles of the invention.
[0025] FIG. 3 shows cross sectional views of various embodiments of
the present invention, indicating different possible micro lens
system designs. The numeral listed in the lower right of each
different configuration indicates the types of possible materials
used to form the micro lens systems.
[0026] FIGS. 4A and 4B show perspective views of preferred carrier
media layers constructed in accordance with the principles of the
invention.
[0027] FIG. 5 shows a cross sectional view of an article that
includes micro lens systems according to the present invention.
[0028] FIG. 6 shows a cross sectional view of another article that
includes micro lens systems according to the present invention.
[0029] FIG. 7 shows a cross sectional view of yet another article
that includes micro lens systems according to the present
invention, and that further includes carrier media layers having
additional optical properties, such as light dispersion or
polarization.
[0030] FIG. 8 shows a cross sectional view of another article that
includes the micro lens systems of the present invention and
carrier media layers having prism-like properties.
[0031] FIGS. 9A and 9B are cross sectional views showing a typical
chemical etching process for forming micro lens systems molding
tools.
[0032] FIGS. 10A, 10B, 10C, and 10D shows are cross sectional views
showing similar typical chemical etching process steps for the
preparation of the micro lens systems molding tools.
[0033] FIG. 11 is a cross sectional view of a typical
electroforming process for the preparation of micro lens systems
molding tools.
[0034] FIG. 12 is a cross sectional view of another typical
electroforming process for the preparation of micro lens systems
molding tools.
[0035] FIG. 13 is a cross sectional view of one of a typical micro
electrochemical machining process for forming micro lens systems
molding tools.
[0036] FIG. 14 is a cross sectional view of another typical micro
electrochemical machining process for the preparation of yet other
types of micro lens systems molding tools.
[0037] FIG. 15 is a cross sectional view showing a typical laser
ablation technique for forming micro lens systems molding
tools.
[0038] FIG. 16 is a cross sectional view showing another typical
laser ablation technique for forming yet another type of micro lens
systems molding tool.
[0039] FIG. 17 is a cross sectional view of an embodiment of the
invention in which an image is reflected back towards the
sources.
[0040] FIG. 18 shows a perspective view of an embodiment of the
invention that utilizes alignment marks to align the micro lens
systems with the carrier media layers.
[0041] FIG. 19 is a perspective view illustrating one process used
to combine the micro lens systems and carrier media layers.
[0042] FIG. 20 shows a perspective view of another process used to
combine the micro lens systems and carrier media layers.
[0043] FIG. 21 is a cross sectional view illustrating a transfer
molding technique for preparing a micro lens molding tool, in which
an electroforming technique is used to prepare a master mold for
the transfer molding tool.
[0044] FIG. 22 is a cross sectional view of another embodiment of
the present invention in which separate micro lens systems are
attached to separate carrier media layers. The carrier media layers
are then attached to a supporting material.
[0045] FIG. 23 is a cross sectional view of a concave micro lens
systems molding tool which uses an electroforming technique to
prepare the master mold for the micro lens systems molding
tool.
[0046] FIG. 24 shows typical prior art structures and materials
used to enhance the overall optical performance of LCD display
devices.
[0047] FIG. 25 shows other prior art structures and materials for
modifying the optical performance of LCD display devices.
[0048] FIG. 26 shows a prior art rear projection screen that uses a
sheet of polymer material to form a plurality of lenses.
[0049] FIG. 27 indicates a typical prior art rear projection screen
in which a single layer optical bead is used to provide the optical
performance of the rear projection screen.
[0050] FIG. 28 shows yet another prior art rear projection screen
of prior arts that uses a sheet of polymer material while providing
different lens structures for optical path modification.
[0051] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
examples in the drawings. However, the intention is not to limit
the invention to the particular embodiments described. The
intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
defined by the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0052] The invention consists of micro lens structures and carrier
layers having optical properties that are combined to form
composite light controlling structures. The micro lens structures
will be described first, followed by descriptions of the carrier
layers, and articles that utilize the composite micro lens/carrier
layer structures of the invention.
[0053] Suitable micro lens systems and micro lens system forming
processes and tools are illustrated in FIGS. 1-3 and 9-16. As
disclosed in FIG. 1, for example, a micro lens mold that may be
used in constructing a micro lens system according to the
principles of the invention includes a relatively thick, flat base
(hereinafter: base) made of materials such as metal, glass,
plastics or polymers (such as polyimide), on which is formed an
array of micro lenses 141, the curvature, size, and related lens
parameters of which are optimized to fit different applications.
Once the micro lens design is fixed, the design of the micro lens
array needed for a large area application can then be done. The
pitch (121) and size (111) of the micro lens array is adjusted
based on the requirements of the particular application. The micro
lens mold rim (151, 153, 155) can have different shapes, sizes, and
orientations, depending on the design of the micro lens systems
array arrangement.
[0054] FIG. 2 shows an alternative to the micro lens mold of FIG.
1. The micro lens mold rim (251, 253, 255) can again have different
shapes, sizes, and orientations, depending on the design of the
micro lens systems array arrangement.
[0055] As can be seen from FIGS. 1 and 2, the shape (141, 241) of
the micro lens system can be modified according to the application
requirements and the design of the micro lens system. For example,
micro lens elements can be designed to have different radii of
curvature in two mutually perpendicular or other different
directions. The pitch (121,221) and size (111,211) of the micro
lens array can also be adjusted based on the requirements of the
particular application.
[0056] The particular illustration in FIG. 2 is oval shaped micro
lens systems (241), in order to provide different optical
performance in different optical axis relative to the major axis of
the lens surface.
[0057] The optical performance of the basic micro lens system can
be further adjusted by the use of different materials during the
formation of the micro lens systems. Polymer or copolymer materials
can include, but are not limited to, such as methyl methacrylate,
hydroxyethyl methacrylate, polystyrene, polycarbonate, polyolefin,
styrene, silicone hydrogel, siloxane, etc. or any other
compositions, and may be mixed with a photo-polymerization or other
suitable polymerization initiator, a mold release agent and/or any
other suitable additives (for anti-static, anti-scratch, and so
forth), a predetermined quantity of the mixture being dispensed
into the molding tool.
[0058] It will of course be appreciated by those skilled in the art
that the micro lens molds illustrated in FIGS. 1 and 2 may be
freely varied without departing from the scope of the invention,
which is intended to cover any micro lens array suitable for
combining with a carrier as described below.
[0059] Also feasible is the mixing of different materials, such as
light diffusing particles or any other suitable bulk diffusers,
into the polymers. The adding of the light dispersing materials can
be done during the material mixing stage.
[0060] Soon after the micro lens materials are dispensed into the
molding tool, a suitable curing process is used to cure the
polymer. Depending on the choice of materials, the cured polymer
can have different indices of refraction. The steps can be
repeated, manipulating the material types, material properties
(viscosity, surface tension and affinities) and process steps to
form the various forms of micro lens systems. The resulting micro
lens systems can have a variety of different optical performance
characteristics.
[0061] FIG. 3 shows various resulting optical arrangements of the
micro lens systems that can be adjusted during the micro lens
system design stage to meet particular requirements. The
illustrated material layers (3111/3113/3114; 3121/3123; 3131/3133;
3141/3143; 3151/3153; 3161/3162; 3171/3173/3174; 3181/3182;
3191/3193; 3201; 3211; 3221/3223; 3231/3233; 3241; 3251; 3261;
3271; 3281; 3291; 3301/3302/3303; 3311/3312; 3321) may include the
same or different polymer materials, with one of the polymer layers
(3113; 3121; 3131; 3141; 3153; 3171; 3201; 3211; 3221; 3231/3233;
3241; 3251; 3261) can be blended with a dispersion material (3112;
3122; 3132; 3142; 3152; 3172; 3202; 3212; 3222; 3232/3234; 3242;
3252; 3262) in order to provide the optical performance required.
Additional non-polymer materials (3192; 3253; 3282; 3321) may be
dispensed into the micro lens systems molding tool before the
above-mentioned polymer materials (3193; 3251; 3281; 3322). These
materials (3192; 3253; 3282; 3321) can be sacrificial materials,
such as micro metallic bead, that can be removed after the micro
lens systems polymer materials are cured. Removal of these
materials can be done via a chemical etching method.
[0062] Although the examples disclosed in the included drawings are
basically convex types of micro lens systems, concave type of micro
lens systems can also be formed without deviation from the present
invention. FIG. 23 shows such a concave type micro lens systems
molding tool formed by a micro electrochemical technique. The micro
lens systems mold forming tool (2311) is first provided by one of
the generally available micro machining techniques, such as diamond
turning, and then micro electrochemical machining is used to finish
the micro lens systems molding tool. With a suitable choice of
chemicals (2341) and process condition, such as tool moving
direction (2331), tool moving speed, temperature, electrode
over-voltage, etc., the micro lens systems molding tool can be
precisely formed in the mold base plate (2321).
[0063] After the micro lens systems design is completed. The
molding tools of the micro lens systems are formed by one of the
various amenable processes to various modifications and alternative
forms. Details of some of the process specifics will be shown by
way of examples in the drawings and will be described in detail
later on.
[0064] One such method of preparing the micro lens systems molding
tool is shown in FIGS. 9 and 10. In FIGS. 9 and 10, a thin
photoresist film (hereinafter: resist) (911; 1011) is coated, by
spraying, dipping, spinning, roller, etc., onto the base (941;
1041). Suitable photolithography (hereinafter photo) techniques can
then be used to form the opening (931; 1031) in the resist. After
the opening is formed, suitable etching chemicals (921; 1021) are
used to etch away the unwanted portion (951; 1051) of the base
(941; 1041) in order to form the micro lens system molding
tools.
[0065] Multiple resist coating, etching, resist striping steps can
be repeated as shown in FIG. 10. In FIG. 10, a thin resist film
(1011) is coated, by spraying, dipping, spinning, roller, etc.,
onto the base (1041). Suitable photo techniques can then form the
opening (1031) in the resist. After the opening is formed, suitable
etching chemicals (1021) are used to etch away thin layer of
unwanted portion (1051) of the base (1041) in order to form the
micro lens system molding tools. In the particular embodiment
illustrated in FIG. 10, a successive repetition of the same process
is used. During each repetition, a different size in the resist
opening is formed and thin layers of the base (1051) are removed.
Such repeated steps can be used to meet the micro lens system's
mold profile design.
[0066] A similar method to prepare the micro lens systems molding
tool is shown in FIGS. 11 and 12. In FIGS. 11 and 12, thin resist
film (1131; 1211) is coated, by spraying, dipping, spinning,
roller, etc., onto the substrate metal coating (1111; 1211).
Suitable photo techniques then form the desired resist pattern.
After the resist pattern is formed, suitable electroforming
chemicals are used to electroform a thin metal layer (1121; 1221)
on the substrate metal coating in order to form the micro lens
system molding tool.
[0067] Multiple resist coating, resist patterning, electroforming,
resist stripping steps can be repeated as shown in FIGS. 11 and 12
to meet the micro lens system's mold profile design. As indicated
in FIGS. 11 and 12, there is a possibility of making different mold
tool styles (1121; 1221), either positive or negative. The
different mold tools styles can be combined with the different
processes and materials described above to facilitate different
methods of preparing the micro lens systems.
[0068] In FIG. 12, a transfer molding tool (1221) for the micro
lens systems is formed first by the electroforming technique onto
the substrate metal coating (1211) of a glass substrate (1231) via
repetition of the successive resist (1211) coating, exposure,
developing, electroforming and striping process steps. This
transfer molding tool is then used to form a micro lens systems
molding tool. As indicated in FIG. 21, the micro lens systems
transferring mold (2121) is electroformed onto the substrate metal
coating (2141) of a glass substrate (2131) via repetition of the
successive resist coating, exposure, developing, electroforming and
striping process steps. Once formed, a suitable material such as
polyimide or any other similarly appropriate compositions may then
be deposited onto the transfer molding tool. After suitable curing
process, the micro lens systems molding tool (2111) is formed from
this transfer molding tool.
[0069] One other method to prepare the micro lens systems molding
tool using micro lens machining techniques is shown in FIGS. 13 and
14. After careful adjustment based on the processing conditions,
materials involved, etc., a replicate of the micro lens system is
made into micro lens systems mold forming tools (1311; 1411). Such
tools can be made by diamond turning or other suitable techniques.
Micro electrochemical machining can then used to shape the micro
lens system molding tools in the base plate (1321; 1421) via the
choice of suitable micro electrochemical machining process
conditions and process chemicals (1341; 1441).
[0070] FIG. 14 shows a different style of micro lens systems. In
such micro lens systems, the major optical axis of the micro lens
systems is basically off-axis. The off-axis major axis can be
varied according to the applications. Different micro lens systems
mold forming tools are used to prepare micro lens systems with
different off-axis angles, according to the application
requirements.
[0071] Yet another micro machining method using laser ablation to
prepare the micro lens systems molding tool is shown in FIGS. 15
and 16. After careful selection of the kind of laser illumination
(1521; 1621) and mold base plate (1511; 1611) to be used, based on
the processing conditions, materials involved, etc., successive
laser ablation techniques are used to `blast away` thin slices of
materials (1531; 1631) from the base. The profile of the micro lens
system molding tools in the base plate can be formed by choice of
repeated laser zapping process conditions, such as laser power,
laser beam size, etc.
[0072] FIG. 16 shows a different style of micro lens systems
similar to the one described above in connection with FIG. 14. By
careful adjustment of the laser ablation machining parameters,
micro lens systems molding tools can be made, with different
off-axis angles, according to the application requirements.
[0073] In addition, based on the application requirements, micro
lens systems molding tools can be made according to combinations of
these available techniques previously described.
[0074] To form the preferred micro lens systems using the
above-described tools, precise quantities of suitable polymer
mixtures are dispensed into the molding tools. Soon after the micro
lens materials are dispensed, suitable curing processes are used to
cure the polymer mixtures. The polymer mixture can be mixed, before
dispensing, with suitable light diffusing particles or any other
suitable bulk diffuser materials. Once cured, the micro lens
systems is ready for further application. The micro lens systems
that are formed can have light dispersing surfaces based on the
micro lens systems forming tool design and/or the polymer materials
that are chosen.
[0075] Articles embodying the present invention include carrier
media layers to which are adhered and/or fused a plurality of micro
lens system for modification of a light path, either or both
horizontally and/or vertically. FIG. 4 discloses one embodiment of
the carrier media layers. In this embodiment of carrier media
layers (411), a plurality of holes (421; 451) of suitable diameter
are formed together with a number of precisely positioned alignment
guide holes (431; 441) which serve as alignment marks for aligning
the carrier layers with the micro lens systems.
[0076] The carrier media layers can be a reflective material, a
transparent material, a light absorbing material, an opaque
material, a metallic material, a photosensitive material, a light
polarizing material and/or other optical material and/or any
suitable combinations of these materials.
[0077] The carrier media layers can also be coated, on one side or
both side of the carrier media layers, with opaque or light
absorbing photosensitive materials and then exposed with suitable
light source. Hole opening in the opaque or light absorbing
material is then formed in alignment with the micro lens systems
that is attached to the carrier media layers.
[0078] The thickness of the layers is chosen based on the
application. The general rule of thumb is to allow the micro lens
system's focus to be located at a desired spatial position.
[0079] If the carrier media layers are to form a polarizing film,
the direction of polarization can be modified depending on the
application. For applications using LCD based displays, where the
light emitted through the LCD device is usually polarized light.
The polarization of the carrier media layers can either be used to
allow or deny the LCD's polarized light to pass through.
[0080] FIGS. 5, 6, 7 and 8, indicate various possible embodiments
of the present invention. In FIGS. 5 and 6, a single layer of
material is used for the carrier media layers (511; 611). In FIG.
5, micro lens systems (531) are attached to one side of the carrier
media layer (511) with a suitable choice of adhesive materials
(521). FIG. 6 includes micro lens systems (631; 641) on both sides
of the carrier media layers (611) with a suitable choice of
adhesive materials (621). Combining the different characteristics
of the carrier media layers and the micro lens systems, different
embodiments can be made for different applications. FIG. 22
indicates yet another embodiment of the present invention, in which
separate micro lens systems (2211; 2241) are attached to separate
carrier media layers (2221; 2251) via a suitable choice of adhesive
materials (2231) and then the separate carrier layers are attached
to the front surface and the back surface of a supporting material
(2261).
[0081] In FIGS. 7 and 8, double layers of materials form the
carrier media layers. Combinations of a reflective material, a
highly transparent material, a light absorbing material, an opaque
material, a metallic material, a photosensitive material, a light
dispersing material, a light retarding material, a light polarizing
material and/or other functional materials can be used to form such
a double layer carrier media.
[0082] In FIG. 7, micro lens systems (711; 741) are attached to the
two sides of the composite carrier media layers (721; 751) with a
suitable choice of adhesive materials (731). As indicated in FIG.
8, a prism-like layer (841) is used together with the micro lens
systems (811), a suitable choice of adhesive materials (821),and
the carrier media layers (831). Such embodiments can find use in
LCD based display devices.
[0083] The micro lens systems and different layers of the carrier
media can be attached together by means of, for example, a thin
photopolymerisable coating such as an ultraviolet-curable
material.
[0084] Based on the applications requirements and the design of the
micro lens systems, the direction of the maximum intensity light
need not lie parallel to an axis normal to the carrier media's
major surface. Such flexibility finds its use in a number of
applications.
[0085] One such application is the projection display system, in
which the screen is used to relay an image into a viewing space.
The viewing space of such a system may be relatively large, or
relatively small. The performance of a projection screen can be
described in terms of various characteristics of the screen, which
typically include gain, viewing angle, resolution, contrast, the
presence of artifacts such as speckle, and the like. It is
generally desirable to have a projection screen that has high
resolution, high contrast, a large gain, and a large viewing
space.
[0086] Unfortunately, as one screen characteristic is improved, one
or more other screen characteristics often degrade. For example, an
increase in the screen gain usually decreases the viewing
angle.
[0087] Screen embodiments utilizing the present invention can
modify the light path in according with the location of the micro
lens systems on the screen s that the light passing through the
articles of the present invention can be more precisely directed
towards the user. The carrier media layers can also be adjusted
according to the application in order to enhance optical
performance.
[0088] In FIG. 17, one embodiment of the present invention is used
to reflect the image back towards the image light sources. This is
typical of a front projection system. By use of suitable carrier
media layers (1711), adhesive materials (1721) and inter-lens space
(1781) filling materials, portions (1775) of the incoming light
(1761), including ambient background light, is absorbed by the
carrier media layers so that extra contrast will be obtained. The
inter-lens space (1781) between each micro lens systems can be
filled with suitable materials to provide a different index of
refraction and/or absorb the light energy incident onto it. The
back of the micro lens systems (1731) can also be coated with
reflective materials (1791) so that incoming light will be
reflected (1771). Additional backing materials can be used to
support the micro lens systems (1731) and articles thereof (1711).
Backing material (1751) can be coated with highly reflective
materials (1741) and adhesive materials (1721) before attachment of
the micro lens systems and articles thereof.
[0089] The articles comprising the present invention can be
manufactured by one of the various amenable processes with various
modifications and alternative forms. Details of some of the process
specifics will be shown by way of examples in the drawings and will
be described in detail later on. FIGS. 18, 19 and 20 disclosed
embodiments of methods of manufacturing the present invention.
[0090] In FIG. 18, the micro lens systems molding tool is presented
as a plate form (1821). In the molding tool, there are alignment
marks (1811) provided at precisely controlled positions. The size
of the molding tool is chosen according to the application. The
carrier media layers composite (1831) is also sized in the same
way. Once the carrier media layers composite and the micro lens
systems are formed, they are bring into position via alignment
marks. With suitable adhering materials (such as a UV-curable
material) and/or process parameters, the micro lens systems and the
carrier media layers composite are fused together and released from
the molding tool. So a batch process of manufacturing the articles
embodying the present invention can be achieved.
[0091] In FIGS. 19 and 20, the micro lens systems molding tools
(1964; 2085) are presented as a continuous plate form. In the
molding tool, there are alignment marks provided at precisely
controlled positions. The width of the micro lens systems molding
tool and the carrier media layers composite (1912, 2017) is chosen
according to the application. The high precision holes that will
hold the micro lens system can be prepared in a off-line or in-line
sequence. The micro lens systems are formed with the continuous
molding tools and suitable dispensing (1974; 2065), curing (1954;
2075), and processing equipment. The reel form carrier media layers
composite (1912; 2017) and the micro lens systems are then brought
into position via the alignment marks. With suitable adhering
materials (1924; 2025), such as UV-curable materials, and/or
processing parameters, the micro lens systems and the carrier media
are fused together and released from the molding tool. So a
continuous process of manufacturing the articles embodying the
present invention can be achieved.
[0092] As will be apparent to those skilled in the art in the light
of the foregoing disclosure, many alternations and modifications
are possible in the practice of this invention without departing
from the spirit or scope thereof. It is to be understood that the
invention is not limited to the disclosed embodiments, but on the
contrary, is intended to cover all of the various modifications and
equivalent arrangements included within the spirit and scope of the
substance of the following claims:
* * * * *