Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/11—Anti-reflection coatings
  • G02B1/118—Anti-reflection coatings having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
  • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/11—Anti-reflection coatings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
  • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
  • B29C59/022—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing characterised by the disposition or the configuration, e.g. dimensions, of the embossments or the shaping tools therefor
  • B29C2059/023—Microembossing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S359/00—Optical: systems and elements
  • Y10S359/90—Methods

Definitions

• 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.
• Reflection of ambient light can occur at a number of surfaces, especially at the dense-rare boundaries of an optical component. As shown in Figure 1, reflection can occur at a number of surfaces of the display and the window on top of the display. Incoming light beam LI 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 RI. 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 Figure 2.
• a surface structure 2 having a pitch P can be imparted on a substrate 5.
• the pitch P of the surface structure 2 must be smaller than the wavelength of the ambient light.
• Ophey et al. U.S. Patent No. 5,694,247, hereafter referred to as Ophey discloses that a grating is imparted on optical components such as lenses and beam-splitters.
• 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 UN 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. Patent No. 5,007,708, hereafter referred to as Gaylord discloses a number of techniques for producing antireflection grating surfaces on dielectrics, semiconductors and metals.
• Gaylord discloses surface-relief grating being formed by reactive ion etching, electron beam lithography, or holography.
• 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.
• 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.
• the attaching of the impressible film to the filter sheet is carried out prior to or after the imparting of the periodic grooves.
• 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.
• 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.
• 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.
• 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.
• 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.
• Figure 1 is a schematic representation illustrating the reflections of ambient light from a number surfaces of an optical device.
• Figure 2 is a schematic representation illustrating an antireflection surface structure, which is a grating with sub-wavelength periodic grooves.
• Figure 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).
• Figure 5 a is a schematic representation illustrating the preferred method of producing a polarizer sheet with an antireflection surface structure, according to the present invention.
• Figure 5b is a schematic representation illustrating a different embodiment of the present invention.
• Figure 5 c is a schematic representation illustrating another embodiment of the present invention.
• Figure 5d is a schematic representation illustrating yet another embodiment of the present invention.
• Figure 6 is a schematic representation illustrating the details of the embossing process, according to the present invention.
• a mobile phone 100 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 Figure 2, on both the top and the bottom dense-rare boundaries (see Figure 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 Figure 4.
• the display 120 comprises a liquid crystal cell 90.
• 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.
• 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.
• the antireflection structure 80 is imparted on the top surface of the top polarizer 70.
• the polarizer 70 (or 72) comprises a stretched polymer film 50 attached with iodine.
• the polymer film 50 can be made of polyvinyl alcohol (PNA), for example.
• PNA polyvinyl alcohol
• 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 (TAG), for example.
• TAG triacetyl cellulose
• the antireflection structure 80 can be directly imparted on the top TAC film 20.
• the antireflection structure 80 is imparted on the TAC film 20 when the polarizer 70 is produced, as shown in Figures 5A - 5D.
• the TAC film 10 is provided in a roll 310 and the mechanically stretched PNA film 30 is provided in a roll 330.
• the TAC and the stretched PNA 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 PNA film.
• the stretched PNA film with iodine attached is denoted by reference numeral 50.
• the TAC film 20 is also provided in a roll 320.
• the iodine-attached film 50, and the TAC film 20 are laminated into a polarizer sheet 60.
• the laminated sheet 60 passes through an embossing station 370, the PNA 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.
• the width of the material rolls 310, 320 and 330 is much wider than the dimension of a typical display on the mobile phone.
• 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 Figure 5A is referred to as a roll-to-roll process 8. This process is suitable for large volume production and is, therefore, cost effective.
• the embossing step is carried out after the iodine-attached stretched film is laminated with two protective TAC films 10, 20.
• the embossing step can be carried out differently.
• the embossing of the top film can be carried out on the film itself prior to lamination.
• the TAC film 20 is first embossed with the antireflection structure 80.
• the embossed TAC film 22 is then laminated with the stretched PNA film 30 into an embossed, laminated film 42 before iodine is attached on the stretched PNA 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.
• the embossing step is carried out after the top TAC film 20 and the stretched PNA film 30 are laminated into a laminated film 44.
• the embossing step is carried out before the iodine attachment process.
• 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.
• Figure 5D Another variation of the roll-to-roll process 8 of Figure 5A is shown in Figure 5D.
• the top TAC film 20 is embossed prior to the film 20 being laminated with the iodine-attached PNA 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.
• the embossing station comprises mainly an embossing roller 372 and a supporting roller 374.
• a pattern is provided for embossing the antireflection structure 80.
• 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 electrofoiming process, this original nickel plate can be used to make the surface of the embossing roller 372.
• 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.
• 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.
• the antireflection structure 80 has a pitch in the range of 150- 400nm, and the depth of the structure is in the range of 75-2000nm.
• the preferred grating profile, as shown in Figure 2, is binary. However, the profile can be triangular or sinusoidal or another periodic form.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Surface Treatment Of Optical Elements (AREA)
• Polarising Elements (AREA)
• Liquid Crystal (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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Citations (4)

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• 2003
  • 2003-03-20 US US10/396,733 patent/US6888676B2/en not_active Expired - Fee Related
• 2004
  • 2004-03-16 JP JP2005518731A patent/JP2006515437A/ja active Pending
  • 2004-03-16 EP EP04720938A patent/EP1604233A4/en not_active Withdrawn
  • 2004-03-16 WO PCT/IB2004/000778 patent/WO2004083143A2/en not_active Ceased

Patent Citations (4)

Non-Patent Citations (1)

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