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Mobile Phone Patent Abstract
A method of producing an antireflection structure for use on a display
or a window surface or both in an electronic device, such as a mobile
phone. The display can be an LCD with a top polarizer and a bottom
polarizer. The antireflection structure is imparted on the top polarizer
by a roller embossing process. In particular, the embossing is carried
out in the same manufacturing process when the polarizer is produced.
The antireflection structure has a plurality of sub-wavelength periodic
grooves. The antireflection structure on the window surface can
be imparted using an embossing process or an injection molding process.
Mobile Phone Patent Claims
What is claimed is:
1. A method of realizing a light reflection reduction structure
on at least one surface of a display, wherein the display has at
least one optical polarizing component disposed thereon and the
reflection reduction structure comprises a plurality of sub-wavelength
periodic grooves, and wherein the polarizing component comprises
an impressible film and a directional optical filter sheet, said
method characterized by attaching the impressible film to the directional
optical filter sheet for forming a laminated sheet, and by imparting
the periodic grooves on the impressible film, said method is further
characterized in that the attaching of the impressible film to the
filter sheet is carried out prior to the imparting of the periodic
grooves.
2. The method of claim 1, characterized in that the directional
optical filter sheet has a first side and an opposing second side,
wherein the impressible film is attached to the first side of the
filter sheet, said method further characterized by attaching a further
film to the filter sheet on the second side thereof.
3. The method of claim 1, characterized in that the directional
optical filter sheet comprises a stretched film, said method further
characterized by applying iodine molecules onto the stretched film
for effecting optical polarization.
4. The method of claim 3, characterized in that said applying is
carried out before the directional optical filter sheet is attached
to the impressible film.
5. The method of claim 1, characterized in that the display comprises
a liquid-crystal display.
6. The method of claim 5, characterized in that the display has
a first side facing a user and an opposing second side, wherein
the optical polarizing component is disposed on the first side.
7. The method of claim 6, characterized in that the display further
has a further optical polarizing component disposed on the second
side of the display.
8. The method of claim 1, characterized in that the imparting step
is carried out using an embossing process.
9. The method of claim 8, characterized in that the imparting of
the periodic grooves on the impressible film is carried out using
a roller having a surface with a pattern for imparting the periodic
grooves.
10. The method of claim 1, further characterized in that the directional
optical filter sheet comprises a stretched film, said method further
characterized by: applying iodine molecules onto the stretched film
for effecting optical polarization, said applying carried out prior
to the imparting of the periodic grooves.
11. The method of claim 1, further characterized in that the directional
optical filter sheet comprises a stretched film, said method further
characterized by: applying iodine molecules onto the stretched film
for effecting optical polarization, said applying carried out after
the imparting of the periodic grooves.
12. A method of realizing a light reflection reduction structure
on at least one surface of a display, wherein the display has at
least one optical polarizing component disposed thereon and the
reflection reduction structure comprises a plurality of sub-wavelength
periodic grooves, and wherein the polarizing component comprises
an impressible film and a directional optical filter sheet, said
method characterized by attaching the impressible film to the directional
optical filter sheet for forming a laminated sheet, and by mechanically
imparting the periodic grooves on the impressible film, wherein
the directional optical filter sheet comprises a stretched film,
said method further characterized by applying iodine molecules onto
the stretched film for effecting optical polarization, and that
said applying is carried out after the directional optical filter
sheet is attached to the impressible film and that the imparting
of the periodic grooves is carried out prior to said attaching.
13. A method of realizing a light reflection reduction structure
on at least one surface of a display, wherein the display has at
least one optical polarizing component disposed thereon and the
reflection reduction structure comprises a plurality of sub-wavelength
periodic grooves, and wherein the polarizing component comprises
an impressible film and a directional optical filter sheet, said
method characterized by attaching the impressible film to the directional
optical filter sheet for forming a laminated sheet, and by mechanically
imparting the periodic grooves on the impressible film, said method
characterized in that the impressible film is part of a film roll
and the optical filter sheet is part of a sheet roll when they are
attached together to form a laminated sheet as part of a laminated
sheet roll, said method further characterized by cutting at least
a part of the laminated sheet roll into sections after said imparting.
Mobile Phone Patent Description
FIELD OF THE INVENTION
The present invention relates generally to an antireflection structure
imparted on a surface of a display or window and, in particular,
to the antireflection structure used on a mobile phone.
BACKGROUND OF THE INVENTION
When a mobile phone is used in a bright ambient light environment,
the reflection of the ambient light from the display can be very
disruptive, making the content of the display difficult to read.
Reflection of ambient light can occur at a number of surfaces, especially
at the dense-rare boundaries of an optical component. As shown in
FIG. 1, reflection can occur at a number of surfaces of the display
and the window on top of the display. Incoming light beam L1 can
reflect at the top and the bottom dense-air boundaries of the window.
The reflected light from the first reflection at the top dense-rare
boundary is denoted by R1. The reflected light from the second reflection
at the bottom dense-rare boundary is denoted by R2. Similarly, light
can also reflect from the top dense-rare boundary of the display,
resulting in reflected light R3. It is advantageous and desirable
to reduce or substantially eliminate the reflections.
Antireflection coatings are known in the art. Usually one or two
thin films of coating material are coated on a substrate surface
in a vacuum chamber to reduce the reflection by destructive interference.
Antireflection coatings are generally expensive because of the cost
involved in the vacuum evaporation process and the low yield of
the coating. It is advantageous and desirable to provide a method
of producing an antireflection surface that is cost-effective.
Sub-wavelength periodic structures have been used for antireflection
purposes. A typical antireflection grating is shown in FIG. 2. As
shown in FIG. 2, a surface structure 2 having a pitch P can be imparted
on a substrate 5. To be used as an antireflection structure, the
pitch P of the surface structure 2 must be smaller than the wavelength
of the ambient light. Ophey et al. (U.S. Pat. No. 5,694,247, hereafter
referred to as Ophey) discloses that a grating is imparted on optical
components such as lenses and beam-splitters. In particular, Ophey
discloses that in an optical transmissive device having an entrance
surface and an exit surface for light transmission, the antireflection
grating imparted on one surface is perpendicular to the antireflection
grating imparted on another surface to avoid birefringent. Ophey
discloses a molding technique combined with UV curing that is used
to impart the grating on synthetic material layers comprised of
poly-methyl methacrylate (PMMA) or polycarbonate (PC). Gaylord et
al. (U.S. Pat. No. 5,007,708, hereafter referred to as Gaylord)
discloses a number of techniques for producing antireflection grating
surfaces on dielectrics, semiconductors and metals. In particular,
Gaylord discloses surface-relief grating being formed by reactive
ion etching, electron beam lithography, or holography.
While the prior art techniques have many advantages for their intended
applications, they may not be applicable or cost-effective when
the antireflection structure is used on a display that requires
one or more polarization components.
SUMMARY OF THE INVENTION
It is a primary objective of the present invention to provide a
cost-effective process for producing an optical structure on a display
or window in an electronic device, such as a mobile phone, for reducing
the boundary reflection on the top of the display or window or both.
This objective can be achieved by using a roller embossing process
to impart the optical structure directly onto an optical polarizer
for use on a liquid-crystal display. This objective can also be
partially achieved by using an injection molding process to impart
the optical structure on a window.
Accordingly, the first aspect of the present invention provides
a method of realizing a light reflection reduction structure on
at least one surface of a display, wherein the display has at least
one optical polarizing component disposed on top thereof, wherein
the reflection reduction structure comprises a plurality of sub-wavelength
periodic grooves, and wherein the polarizing component comprises
an impressible film and a directional optical filter sheet. The
method is characterized by attaching the impressible film to the
directional optical filter sheet for forming a laminated sheet,
and by imparting the periodic grooves on the impressible film.
Advantageously, the attaching of the impressible film to the filter
sheet is carried out prior to or after the imparting of the periodic
grooves.
Advantageously, the directional optical filter sheet has a first
side and an opposing second side and the impressible film is attached
to the first side of the filter sheet. The method is further characterized
by attaching a further film to the filter sheet on the second side
thereof.
Preferably, the directional optical filter sheet comprises a stretched
film. The method is further characterized by applying iodine molecules
onto the stretched film for affecting optical polarization.
Advantageously, the display comprises a liquid-crystal display
and the display has a first side facing a user and an opposing second
side, wherein the optical polarizing component is disposed on the
first side.
Preferably, the imparting step is carried out using an embossing
process using an embossing roller.
The second aspect of the present invention provides an optical
component for use in an optical device. The optical component is
characterized by: a directional optical filter sheet, and by an
impressible film, wherein the impressible film has a first side
and an opposing second side attached to the directional optical
filter sheet, and the first side of the impressive film includes
a sub-wavelength periodic structure embossed thereon for reducing
light reflection from the first side of the impressive film.
Advantageously, the optical device comprises a liquid-crystal display.
The third aspect of the present invention provides a mobile terminal,
which comprises: means for communicating with a network component
in a communications network, a display for displaying information,
a surface having a microstructure positioned relative to the display
for reducing light reflection, and at least one optical polarizing
component disposed between the surface and the display, wherein
the microstructure comprises a plurality of sub-wavelength grooves.
The surface can be spaced from the optical polarizing component
and can be used as a window, but the surface can also be attached
to the optical polarizing component as part of the display. The
sub-wavelength grooves on the window can be imparted by a roller
embossing process or an injection molding process.
The present invention will become apparent upon reading the description
taken in conjunction with FIGS. 3 to 6.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation illustrating the reflections
of ambient light from a number surfaces of an optical device.
FIG. 2 is a schematic representation illustrating an antireflection
surface structure, which is a grating with sub-wavelength periodic
grooves.
FIG. 3 is a schematic representation illustrating a mobile phone
having a display.
FIG. 4 is a schematic representation illustrating a typical liquid-crystal
display (LCD).
FIG. 5a is a schematic representation illustrating the preferred
method of producing a polarizer sheet with an antireflection surface
structure, according to the present invention.
FIG. 5b is a schematic representation illustrating a different
embodiment of the present invention.
FIG. 5c is a schematic representation illustrating another embodiment
of the present invention.
FIG. 5d is a schematic representation illustrating yet another
embodiment of the present invention.
FIG. 6 is a schematic representation illustrating the details of
the embossing process, according to the present invention.
BEST MODE TO CARRY OUT THE INVENTION
A mobile phone 100, as shown in FIG. 3, has an antenna for communicating
with another network component in a communications network, a display
120 for displaying information, and a window 110 on top of the display
120 for protecting the display 120 or for decorative purposes. It
is desirable to impart an antireflection structure, such as that
shown in FIG. 2, on both the top and the bottom dense-rare boundaries
(see FIG. 1) of the window 110. The antireflection structure on
the window can be imparted by an embossing process or an injection
molding process. Furthermore, it is desirable to impart a similar
antireflection structure on top of the display 120, as shown in
FIG. 4. In particular, if the display is a liquid-crystal display
(LCD) or the like, it is preferable to impart an antireflection
structure on the top surface of the display. As shown in FIG. 4,
the display 120 comprises a liquid crystal cell 90. Typically the
liquid crystal cell comprises an upper plate 92 and a lower plate
94 forming a gap therebetween to accommodate a layer of liquid crystal
material 96. The liquid crystal cell 90 is placed between two polarizers
70, 72. LCDs are known in the art and are not part of the invention.
According to the present invention, an antireflection structure
80 is provided on top of the LCD 120 in order to reduce the reflections
of ambient light from the top the LCD. In particular, the antireflection
structure 80 is imparted on the top surface of the top polarizer
70. Typically, the polarizer 70 (or 72) comprises a stretched polymer
film 50 attached with iodine. The polymer film 50 can be made of
polyvinyl alcohol (PVA), for example. The stretched polymer film
50 attached with iodine is used as a directional optical filter
to produce linearly polarized light from natural unpolarized light.
This filter is laminated between two polymer sheets or films 10,
20, for example. The polymer films 10, 20 can be made of triacetyl
cellulose (TAC), for example. According to the present invention,
the antireflection structure 80 can be directly imparted on the
top TAC film 20.
It is preferred that the antireflection structure 80 is imparted
on the TAC film 20 when the polarizer 70 is produced, as shown in
FIGS. 5A-5D. As shown in FIG. 5A, the TAC film 10 is provided in
a roll 310 and the mechanically stretched PVA film 30 is provided
in a roll 330. Through a pair of laminating rollers 390, the TAC
and the stretched PVA film 30 are laminated together into a laminated
film 40. An iodine attachment apparatus 350 is then used to attach
iodine molecules onto the stretched PVA film. The stretched PVA
film with iodine attached is denoted by reference numeral 50. The
TAC film 20 is also provided in a roll 320. Through a pair of laminating
rollers 360, the iodine-attached film 50, and the TAC film 20 are
laminated into a polarizer sheet 60. As the laminated sheet 60 passes
through an embossing station 370, the PVA film 20 side of the laminated
sheet 60 is embossed with the antireflection structure 80, preferably
using a hot-embossing process. It is preferred that the embossed,
laminated sheet 70 in a roll form is cut by a cutter 380 into cut
sheets 74. In general, the width of the material rolls 310, 320
and 330 is much wider than the dimension of a typical display on
the mobile phone. For example, the width of the rolls can be about
1 meter (approximately 3 feet), and the cut sheets can be 1 meter
by 1 meter, for example. The producing method, as shown in FIG.
5A, is referred to as a roll-to-roll process 8. This process is
suitable for large volume production and is, therefore, cost effective.
In the preferred fabricating process, as shown in FIG. 5A, the
embossing step is carried out after the iodine-attached stretched
film is laminated with two protective TAC films 10, 20. However,
the embossing step can be carried out differently. For example,
the embossing of the top film can be carried out on the film itself
prior to lamination. As shown in FIG. 5B, the TAC film 20 is first
embossed with the antireflection structure 80. The embossed TAC
film 22 is then laminated with the stretched PVA film 30 into an
embossed, laminated film 42 before iodine is attached on the stretched
PVA film 30. The embossed, laminated film with iodine attached is
denoted by reference number 52. The embossed film 52 is further
laminated with the bottom TAC film 10.
Alternatively, the embossing step is carried out after the top
TAC film 20 and the stretched PVA film 30 are laminated into a laminated
film 44. However, the embossing step is carried out before the iodine
attachment process. As shown in FIG. 5C, the laminated film 44 is
embossed into an embossed, laminated film 46 before it is attached
with iodine. The iodine-attached film is denoted by reference number
48. The laminated film 48 and the bottom TAC film 10 are then lamination
into the polarizer sheet 70.
Another variation of the roll-to-roll process 8 of FIG. 5A is shown
in FIG. 5D. As shown, the top TAC film 20 is embossed prior to the
film 20 being laminated with the iodine-attached PVA film 50 and
the lower TAC film 10 to become the polarizer sheet 70.
FIG. 6 is a schematic representation illustrating the embossing
station 370. As shown, the embossing station comprises mainly an
embossing roller 372 and a supporting roller 374. On the surface
of the embossing roller 372, a pattern is provided for embossing
the antireflection structure 80. Typically, the pattern is made
on a substrate by holographic lithography or electron-beam lithography
and etched into a surface-relief structure. An electroforming process
is then employed to generate a nickel plate (the so-called mother
shim). Using the same electroforming process, this original nickel
plate can be used to make the surface of the embossing roller 372.
Using such an embossing roller to impart an antireflection structure
directly on a polarizer during the same manufacturing process is
advantageous in terms of manufacturing cost and product consistency.
In particular, the roller embossing process for producing an antireflection
structure is continuous and repeatable. Other methods for producing
an antireflection surface, such as vacuum deposition or evaporation,
reactive ion etching and electron beam lithography, are not continuous
and repeatable.
As shown in FIG. 4, the antireflection structure 80 is imparted
only on one side of the top polarizer 70. However, it is also possible
to impart a similar antireflection structure 80 on the other side
of the top polarizer 70. Furthermore, it is also possible to have
one or two additional antireflection structures 80 imparted on the
window 110 (FIG. 3). Preferably, the antireflection structure 80
has a pitch in the range of 150-400 nm, and the depth of the structure
is in the range of 75-2000 nm. The preferred grating profile, as
shown in FIG. 2, is binary. However, the profile can be triangular
or sinusoidal or another periodic form.
Although the invention has been described with respect to a preferred
embodiment thereof, it will be understood by those skilled in the
art that the foregoing and various other changes, omissions and
deviations in the form and detail thereof may be made without departing
from the scope of this invention.
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