The present application is related to and claims the benefit of New Zealand Provisional Patent Application Number 549182, filed Aug. 15, 2006, entitled “IMPROVED DIFFUSER AND METHOD OF MAKING THE SAME,” naming Gareth Bell and Robert Craig as the inventors, and assigned to the assignee of the present invention. That application is incorporated herein by reference in its entirety and for all purposes.
Multi-layer displays (MLDs), sometimes referred to as multi-component displays (MCDs), include multiple display screens (e.g., LCD displays) in a stacked arrangement. Each of the display screens may have its own set of color filters and/or its own matrix which covers the traces, leads and transistors of each pixel. When the display screens are overlaid, the repeated elements can produce visually-offensive banding or other interference patterns known as Moiré interference. As such, it is common to introduce an optical diffuser between the display screens of the MCD to reduce the Moiré interference.
Conventional optical diffusers (e.g., 150) can only be produced in low volume and are expensive to manufacture. For example, each step depicted in
Accordingly, a need exists for an optical diffuser which can be produced in larger volumes and at lower cost. A need also exists for an optical diffuser with reduced distortion during use. Embodiments of the present invention provide novel solutions to these needs and others as described below.
Embodiments of the present invention are directed to an improved optical diffuser for use in a multi-component display (MCD), and also to a method of manufacturing the same. More specifically, embodiments provide an optical diffuser film which may be manufactured with fewer manual operations (e.g., as an automated roll-to-roll process), at a lower cost, and in larger volume than conventional optical diffusers. The optical diffuser film may include a flexible polymer substrate (e.g., polycarbonate, etc.) coupled to an optical diffuser material (e.g., UV-curable epoxy) with a plurality of features (e.g., embossed using a pressed or rolled master pattern) for diffusing light. The novel optical diffuser film may be stored, transported, or otherwise handled more easily and with less damage than conventional optical diffusers. Additionally, the optical diffuser film may be coupled (e.g., using a pressure-sensitive adhesive) to a rigid substrate (e.g., glass) to reduce distortion (e.g., thermally-induced distortion caused by backlight lamps, light emitting diodes (LEDs), or other light sources of the MCD during use) of the optical diffuser, thereby providing improved optical performance.
In one embodiment, an optical diffuser film includes a flexible polymer substrate. The optical diffuser film also includes an optical diffuser material with a first surface disposed on the flexible polymer substrate and a second surface including a plurality of features for diffusing light passed through the optical diffuser material. The flexible polymer substrate may include a polycarbonate film, where the polycarbonate film may be selected from a group consisting of solvent-cast polycarbonate film and chill-rolled polycarbonate film. Additionally, the optical diffuser material may include a polymer curable by ultraviolet light (e.g., a UV-curable epoxy, etc.). The flexible polymer substrate and the optical diffuser material may form an optical diffuser film for reducing Moiré interference associated with multi-component displays.
In another embodiment, an optical diffuser includes an optical diffuser film. The optical diffuser film includes a flexible polymer substrate and an optical diffuser material with a first surface disposed on the flexible polymer substrate and a second surface including a plurality of features for diffusing light passed through the optical diffuser material. A rigid substrate is disposed on the optical diffuser film for providing structural support for the optical diffuser film. The rigid substrate may include glass. Additionally, the rigid substrate may further be operable to reduce thermal deformation of the optical diffuser film. The optical diffuser may include a pressure-sensitive adhesive for adhering the optical diffuser film to the rigid substrate. The optical diffuser film and the rigid substrate may form an optical diffuser for reducing Moiré interference associated with multi-component displays.
In yet another embodiment, a multi-component display includes a first display and a second display overlapping the first display, wherein the first and second displays are capable of displaying graphical objects. An optical diffuser is disposed between the first and second displays, the optical diffuser including an optical diffuser film. The optical diffuser film includes a flexible polymer substrate and an optical diffuser material with a first surface disposed on the flexible polymer substrate and a second surface including a plurality of features for diffusing light passed through the optical diffuser material. The optical diffuser also includes a rigid substrate disposed on the optical diffuser film and for providing structural support for the optical diffuser film. The multi-component display may also include a backlight for generating light passed through the first display, the optical diffuser and the second display.
In another embodiment, a method of manufacturing an optical diffuser includes adhering an optical diffuser film to a rigid substrate, wherein the rigid substrate is operable to provide structural support for the optical diffuser film. The optical diffuser film may include a flexible polymer substrate and an optical diffuser material with a first surface disposed on the flexible polymer substrate and a second surface including a plurality of features for diffusing light passed through the optical diffuser material. The method may further include applying the optical diffuser material to the flexible polymer substrate and embossing the plurality of features into the optical diffuser material. The applying and the embossing may form a roll-to-roll process. Additionally, the embossing may further include applying a master pattern to the optical diffuser material (e.g., pressing a substantially-flat master pattern into the optical diffuser material, rolling a cylindrical master pattern over the optical diffuser material, etc.), the master pattern including a second plurality of features for forming the plurality of features in the optical diffuser material. The optical diffuser material may be cured to form the plurality of features in the optical diffuser material.
The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements.
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. While the present invention will be discussed in conjunction with the following embodiments, it will be understood that they are not intended to limit the present invention to these embodiments alone. On the contrary, the present invention is intended to cover alternatives, modifications, and equivalents which may be included with the spirit and scope of the present invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present invention.
Graphical objects 225 and/or 235 may comprise any visual display of a respective display screen (e.g., 220, 230, etc.). In one embodiment, graphical objects 225 and/or 235 may comprise still images. The still images may comprise stand-alone images, or alternatively, frames of a video or other moving imagery. Alternatively, graphical objects 225 and/or 235 may comprise frame-less moving imagery. Additionally, graphical objects 225 and/or 235 may comprise multiple distinct images, contiguous portions of the same image, non-contiguous portions of the same image, low-pass or high-pass filtered versions of the same image, etc.
As shown in
Optical diffuser 210 may comprise an optical diffuser with a micro-structured profile (e.g., with features that are not visible to the naked eye and/or which manipulate light in ways that are not apparent to the naked eye) for reducing Moiré interference associated with MCD 200. Optical diffuser 210 may comprise a customized output scattering profile, a Gaussian profile, a triangular profile, a square profile, an elliptical profile, etc. In one embodiment, optical diffuser 210 may comprise a holographic diffuser. In other embodiments, optical diffuser 210 may provide other optical manipulation (e.g., filtering, retardation, polarization, etc.) of light (e.g., graphical objects 225 emitted from display 220, light emitted from backlight 240, etc.) passed through optical diffuser 210.
Although
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Substrate 312 may be flexible. For example, substrate 312 may be relatively thin (e.g. with a height substantially less than other dimensions associated with the surface coupled to optical diffuser material 314) or otherwise comprise a thin film, have mechanical properties enabling flexing or bending, etc. As such, optical diffuser film 310 may comprise a flexible optical diffuser film which can be stored, transported, or otherwise handled more easily and with less damage than conventional optical diffusers. For example, optical diffuser film 310 may be rolled into a roll when not in use, thereby providing a compact configuration (e.g., for storage, transportation, etc.) which also enables easy removal for use (e.g., unrolling optical diffuser film 310 from the roll for use).
As shown in
In one embodiment, substrate 312 may comprise a solvent-cast polycarbonate film such as Pokalon from LOFO High Tech Film of Germany, solvent-cast polycarbonate films from TEJIN Films of Japan, or solvent-cast polycarbonate films from GE of the United States. Alternatively, substrate 312 may comprise a chill-rolled polycarbonate film such as EUROPLEX 0F405 from Degussa. And in other embodiments, substrate 312 may be implemented using Arylite A100HC polyarylate from Ferrania, Zeonor ZF16-100 cyclic polyolefin from Zeon, or Ultrason E2010 Q28 polyethersulphone from BASF.
Optical diffuser material 314 may comprise a material whose curing can be controlled. For example, optical diffuser material may comprise a photosensitive material (e.g., which cures when exposed to ultraviolet light or other light), chemically-cured material, etc. As such, features 316 may be created in material 314 (e.g., using embossing as discussed below with respect to
In one embodiment, optical diffuser material 314 may comprise a UV-curable epoxy with a viscosity of approximately 200-400 cps such as Gaffgaurd 233 from GAF corporation of New Jersey or AC PR153/AC PR155/AC PR157 from Addison Clear Wave of Illinois. Additionally, optical diffuser material 314 may comprise one or more additives (e.g., to increase bonding strength with substrate 312) such as 1,6-Hexanediol diacrylate or tetrahydrofurfuryl acrylate.
As shown in
In one embodiment, substrate 330 may comprise glass (e.g., with a thickness of 1 mm to 10 mm). For example, glass sheet such as Schott Desag B270, Schott Borofloat, Schott D263T Borosilicate, Schott Robax Glass Ceramic, Schott AF45 Alkali-free glass, Vycor, or Float glass (soda lime) may be used. In other embodiments, other substrate materials may be used which provide maximum flatness variation of approximately 0.1 mm, a weight of approximately 0.01 g/mm2, a minimum optical transmission of approximately 90%, a maximum color shift of approximately 0.004 uv, an allowable temperature range of −20 K to 85 K, a maximum linear coefficient of expansion of approximately 10 10−6/K, an acceptable humidity of approximately 8/95% RH, a minimum knoop hardness of approximately 565 kgf/mm2, a maximum Young's modulus of approximately 7.2*1010 Pa, a maximum Poisson's Ratio of approximately 0.22, or some combination thereof.
In other embodiments, substrate 330 may comprise an LCD polarizer. Alternatively, substrate 330 may comprise one or more other optical components.
As shown in
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Once material 314 is applied to substrate 312, features 316 may be created. For example, master pattern 410 (e.g., a negative mold of features 316) may be pressed into optical diffuser material 314 and held there while light (e.g., ultraviolet light, etc.) from light source 430 is applied to cure material 314. Once material 314 is cured, master pattern 410 may be removed to reveal features 316 which are formed or held in place on the top surface of material 314.
Features 316 may also be created in material 314 by rolling master pattern 420 over material 314. Master pattern 420 may comprise a negative mold of features 316 disposed around the circumference of a cylinder in one embodiment. Light (e.g., ultraviolet light, etc.) may be applied from light source 440 to cure material 314, where light source may be rotated to “follow” master pattern 440 (e.g., curing portions of material 314 in which features 316 are formed), held in a fixed position similar to light source 430 (e.g., to cure material 314 after master pattern 420 has finished creating features 316), or otherwise positioned and/or moved to cure material 314.
Once features 316 are created in material 314, optical diffuser film 310 may be rolled in roll 450 for storage, transportation, subsequent use (e.g., in an automated roll-to-roll process, etc.), etc. Alternatively, optical diffuser film 310 may be coupled to substrate 320 (e.g., using adhesive material 330) to form optical diffuser 210. As shown in
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Step 730 involves creating features in the optical diffuser material (e.g., 314) to form an optical diffuser film. The features (e.g., 316) may be configured, shaped, arranged, etc. to diffuse light passed through the optical diffuser material. Additionally, the features (e.g., 316) may be created by embossing (e.g., applying a master pattern and curing the optical diffuser material to set or hold the features in place as discussed above with respect to
As shown in
Alternatively, after accessing a second substrate (e.g., 320) and an adhesive material (e.g., 330) in step 750, the optical diffuser film (e.g., 310) produced in step 730 may be coupled to the second substrate (e.g., 320) using the adhesive material (e.g., 330) to form an optical diffuser (e.g., 210) in step 760. As such, in one embodiment where the second substrate (e.g., 320) comprises a rigid substrate (e.g., that retains shape under thermal and/or mechanical loading), the second substrate (e.g., 320) may reduce bending, flexing, or other distortion of the optical diffuser film (e.g., 310). Thus, the second substrate (e.g., 320) may improve the optical properties of the optical diffuser film (e.g., 310).
In the foregoing specification, embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Thus, the sole and exclusive indicator of what is, and is intended by the applicant to be, the invention is the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction. Hence, no limitation, element, property, feature, advantage, or attribute that is not expressly recited in a claim should limit the scope of such claim in any way. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.