WO2021096533A1

WO2021096533A1 - Optical reflector film, display with optical reflector film and method of manufacturing an optical reflector film

Info

Publication number: WO2021096533A1
Application number: PCT/US2019/061798
Authority: WO
Inventors: Shaopeng ZHU; Rong Wu; Shasha LIU
Original assignee: Applied Materials, Inc.
Priority date: 2019-11-15
Filing date: 2019-11-15
Publication date: 2021-05-20

Abstract

According to embodiments of the present disclosure, one or more embodiments of optical reflector films and a display with such a film are disclosed. The optical reflector film comprises a layer stack comprising at least a first metallic layer and at least a first plastic layer. The layer stack further comprises a first layer, comprising one of a layer from a multi-layered plastic foil or one or more layers of inorganic materials.

Description

OPTICAL REFLECTOR FILM, DISPLAY WITH OPTICAL REFLECTOR FILM AND METHOD OF MANUFACTURING AN OPTICAL REFLECTOR

FILM

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to an optical reflector film to be applied e.g. to displays and panels for improving the distribution of backlight. Further, the present disclosure relates to a method of manufacturing such an optical reflector film and a display device, e.g. an LED panel, which is equipped with an optical reflector film according to the present disclosure.

BACKGROUND

[0002] Einlike self-emissive flat panel displays, non-emissive flat panel displays such as liquid crystal display (LCD) panels need external light to produce an image. Thus, a backlight unit may be located behind a non-emissive flat panel display and illuminates light on the flat panel display such as an LCD panel in order to produce an image.

[0003] The backlight unit for the flat panel display may be used as a backlight unit for an LCD device or a surface light source system such as an illuminating sign. Backlight units are classified as direct light type backlight units and edge light type backlight units according to the position of a light source arranged. A point light source having an approximately point-shaped light-emitting portion or a linear light source having a linear lightemitting portion disposed along one direction may be used as a light source for an edge light type backlight unit.

[0004] Typically, backlights unit may use a reflector film. The reflector film, among others, has the objective to reflect parts of the light, emitted by the light sources (typically LEDs or CCFL tubes) which otherwise would be lost and would therefore not contribute to a proper illumination of the panel. [0005] This results in poor brightness and colors of the screen. Available reflector films comprise a plastic foil as a base material, on which a thin metallic layer may be deposited. The metallic layer may be responsible for reflecting light back into the display. [0006] Such a film or foil may be very thin and may be applied to the backlight of a panel during manufacturing. The panels in production are very big and are cut into usable panel sizes for e.g. mobile phones or other displays in one of the last production steps, when backlight and reflector film/foil have been applied to the panel

[0007] Currently available films/foils however suffer some disadvantages. Due to the existence of a thin reflective metal normally prone to corrosion by ambient moisture/oxygen, sufficient protection is needed for that metal, which might affect the reflectivity and color performance of the films/foils to support the increasing need of a high-luminance display. Additionally, they need very careful mechanical handling due to scratches and cracks, in particular when they are cut to fit the sizes of the panels. [0008] On reflector films known to the inventors, inorganic layers are used only on top of a silver (Ag), metallic reflector layer. However, inorganic oxides are normally fragile (like glass) and if they are supported by a hard metal only, they tend to crack near the cutting edge when the film is cut. Furthermore, the material selection of inorganic layers may be limited by the adhesive force between silver and the layer of choice or the adhesive force between different layers. Only materials that may have a sufficient intrinsic adhesive force may be chosen to be directly in contact. An optimized optical design of the inorganic layers, however, may require the contact of materials having insufficient adhesive force and a method may be desirable to realize such designs. [0009] On another known reflector film, an organic layer is coated or laminated on top of a silver layer (reflector), which may be possibly more robust during mechanical handling, however, such film’s optical performance may not be properly controllable. This is, the films/foils are not only used for a proper reflection of the light but also to adjust a color behavior of the light from the light sources (LEDs, CCFL). The film may influence the color of the reflected light and therefore also the color of a picture displayed on the panel.

[0010] Accordingly, there is a need for an optical reflector film with improved characteristics for reflection, color behavior, reliability and mechanical stability, in particular mechanical stability during processing. There is further the need for optical displays which benefit from the increased characteristics of such an optical reflector film.

SUMMARY

[0011] In light of the above, in a first aspect, an optical reflector film comprising a stack of layers may be provided.

[0012] The stack of layers may comprise at least a first metallic layer and at least a first plastic layer. The stack may further comprise a first layer, comprising one of a layer from a multi-layered plastic foil or one or more layers (sub-layers) of inorganic materials. The layer stack may further comprise additional layers of organic material and/or layers of a material configured to enhance an adhesion between specific layers.

[0013] According to another aspect, an optical reflector film is disclosed comprising a stack of layers. The layers may be arranged in a sequence of: a plastic layer, a metallic layer, a layer of a plastic foil or a layer of inorganic materials. The plastic foil may be a multilayered plastic foil. The layer of inorganic materials may comprise one or more sublayers of different inorganic materials. Further layers of organic materials and adhesion/barrier (adhesion enhancement or bonding layers) layers may be added to the stack.

[0014] According to yet a further aspect, an optical reflector film comprising a stack of layers is disclosed. The layers may be arranged in a sequence of: a plastic layer; a metallic layer; and a layer of inorganic materials, wherein the layer of inorganic materials comprises one or more sublayers of different inorganic materials. Further layers of organic materials and/or adhesion/barrier layers may optionally be added to the stack. [0015] According to a further aspect of the present disclosure, a method of manufacturing such an optical reflector film is disclosed. The method of manufacturing a reflective film according to other aspects of the present disclosure may comprise of providing a plastic layer; depositing a metallic layer on the plastic layer; further depositing an organic layer on the metallic layer and depositing an inorganic layer on the organic layer.

[0016] In another aspect, an optical display with an optical reflector film according to other aspects is disclosed.

[0017] Further aspects, advantages and features of the present disclosure are apparent from the description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following. Typical embodiments are depicted in the drawings and are detailed in the description which follows.

[0019] FIGS la) to lc) are a schematic illustration of known reflection foils;

[0020] FIG. 2 is a schematic illustration of an optical reflection foil according to embodiments of the disclosure as described herein;

[0021] FIG. 3 is a schematic illustration of a use of an optical reflector foil according to embodiments described herein;

[0022] FIG. 4 shows a color-space diagram illustrating reflection and transmission of a reference optical reflector film; [0023] FIG. 5 shows a color-space diagram illustrating reflection and transmission of a film according to embodiments described herein;

[0024] FIG. 6 is a diagram showing characteristics of an optical reflector film device according to embodiments described herein; [0025] FIG. 7 illustrates different amount and kinds of layers in stacks according to embodiments of the disclosure;

[0026] FIG. 8 shows in a comparative way different layer stacks according to embodiments of the disclosure;

[0027] FIG. 9 shows a detailed embodiment of a layer stack according to embodiments of the disclosure;

[0028] FIG. 10 shows optical characteristics of a layer stack according to a variant of embodiments of the present disclosure, in comparison to a layer stack known to the inventors;

[0029] FIG. 11 shows optical characteristics of a layer stack according to another variant according to embodiments of the present disclosure, in comparison to a layer stack known to the inventors;

[0030] FIG. 12 shows reflection characteristics of layer stacks in a comparative way;

[0031] FIG. 13 shows an exemplary manufacturing process of a layer stack according to embodiments; [0032] FIG. 14 discloses a flow chart of a method to manufacture an optical reflector film according to one or more embodiments of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0033] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in the figures. Each example may be provided by way of explanation and may be not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It may be intended that the present disclosure includes such modifications and variations.

[0034] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment applies to a corresponding part or aspect in another embodiment as well.

[0035] FIGS. 1 a) to c) illustrate some known kinds of films used in the art and show reflective films with three layers.

[0036] FIGS la) shows a film comprising a stack with a plastic layer (plastic foil) 120 as the lower film, a metallic layer 110 with reflective characteristics as an intermediate layer and an organic layer 100 to protect the metallic layer 110 against e.g. oxidation or mechanical damages. A film as can be seen in FIG. la) may be hardly designable in color characteristics. The film is optically not designable in color coordinates. Also, this film/foil may suffer from an insufficient protection by only the organic layer 100 on the metallic layer.

[0037] FIG. lb) shows a film comprising a stack with a plastic layer 120 as the lower film, a metallic layer 110 with reflective characteristics as an intermediate layer and an inorganic layer 130 on top, covering the metallic layer 110. Generally, inorganic layers are fragile and there is the danger that they may get cracks when cut. The surface has to be protected, otherwise the surface may be damaged (e.g. scratched), when handled during processing.

[0038] FIG. lc) shows another available foil/film. A metallic layer 110 is “sandwiched” between two plastic layers 120. One of the plastic layers 120 is thicker than the other. The thinner layer is arranged towards the panel. However, due to the material, it is not possible to make the plastic layers very thin. This negatively influences an optical performance by the thick foil on the reflective (metal) layer 110. The usage of plastic layers 120 as the upper and lower layer also limits the reduction in thickness of the film since the plastic films (plastic layer) cannot be as thin as the metallic/organic/inorganic layers, which can be deposited in thicknesses in the nm range.

[0039] In the present disclosure, the term “layer” may refer to a layer which may also comprise several “sub layers”. The sub layers may each be another material, different from one another. The materials however may be in a common chemical class with similar chemical and mechanical characteristics.

[0040] FIG. 2 schematically illustrates an optical reflector film/foil according to an embodiment of the present disclosure. On a plastic foil/film 120, a metallic layer 110 for reflecting light may be deposited. The metallic layer 110 may be covered with a layer 100 of an organic coating. This organic layer 100 may be a transparent layer. The organic layer 100 may be further covered by an inorganic layer 130.

[0041] As can be further seen from FIG. 2, inorganic layer 130 may comprise of a plurality of different layers 200, 210, 220 each made of a different inorganic material. The number of inorganic layers may be not restricted to the three layers shown. The number of inorganic layers 130, 200, 210, 220 can be one single layer, comprising one inorganic material or may comprise several sub layers 200, 210, 220, stacked, each comprising a different inorganic material. The inorganic layer 130 may form a good barrier on the organic coating 100. The organic layer 100 below the inorganic layer 130 can have a formulation design (chemical/mechanical characteristics) which provides an improved adhesion on metal layer 110.

[0042] The organic layer 100 may provide a smooth surface, like a planarization layer, to enhance the barrier performance of inorganic layer 130. Inorganic layer 130, formed on organic layer 100, may advantageously improve cracking-resistance. Even if some cracks form in one of the layers, they may not expose the reflector layer 110 (e.g. Ag, AL or Ag alloy) directly to the influence of ambient conditions, due to the existence of the organic layer and thus an area with one or more cracks may remain substantially unaffected, even if moisture/oxygen is present. [0043] However, in some reflector films known to the inventors which use an inorganic layer directly on an Ag-layer (see FIG. lb), the moisture/oxygen penetrating through the cracks in the layers may very likely ‘eat up’ the Ag-reflector film underneath. This makes the cracks collapse and further deteriorate the area like an avalanche.

[0044] In FIG. 3, an arrangement is shown in which a film or foil according to embodiments of the present disclosure may be used in a display to enhance a distribution of light. A light source 300, for example an LED, may be arranged at the edge of a light conductor 320. The light source 300 sends light, represented by arrows, into the light guide 320. Parts of the light leave the light conductor/guide 320 towards the LCD/LED panel through a diffuser 310 which may be responsible for an equal distribution of the light.

[0045] The optical reflector film, represented by the layer stack comprising the layers 100 - 130, may be arranged below the light guide 320. As can be seen, light rays (see the encircled ray) would normally leave the light guide. The light of these light rays would be lost for illumination of the LED/LCD panel above and the brightness of the panel would be negatively influenced. This otherwise lost light may be reflected back by the reflector film towards the LCM and thus maintains a high brightness of the display. [0046] In FIG. 4, a diagram 400 is shown, showing the reflection and transmission of a reference reflector film, with an arrangement in the table to the left. This film comprises a reflector comprising a silver layer (1, Ag) with a specific thickness and a coating layer (2, CoatL) with the second thickness.

[0047] A wet coating process may achieve micron-level organic coating. With an advanced formulation and process, thickness may advantageously be reducible to thicknesses of below 300nm. In particular, they can be reduced to thicknesses in a range from 200-3 OOnm. The optimal thickness may be a balance of optical (thinner may be better) and mechanical/chemical protection (thicker may be better) performances. The diagram shows a color space (the area surrounded by the horseshoe shaped thin line) illustrating that the transmission and reflection value are quite far apart.

[0048] FIG. 5 shows a similar diagram 500 of an optical reflector film according to the present disclosure. The metallic silver layer (1, Ag) may be covered with a coating layer (2, CoatL). The coating layer may be covered by three layers of inorganic materials (TiCh, S1O2) wherein a silicon dioxide (S1O2) layer may be sandwiched between two (layers 3 and 5) Titan dioxide layers (T1O2). The three TiC /SiC layers (“sub-layers”) can be considered to form one inorganic layer. Generally also layer formulations of SiOx/TiOx are possible depending on the characteristics which the layer has to meet.

[0049] FIG. 6 shows an average reflection rate 600 of an optical reflection film according to the present disclosure as a function of the wavelength versus the reflection rate of a reference foil according to a reference foil/film.

[0050] FIG. 7 shows layers used in different embodiments 700 of the stack according to the disclosure. The layers in FIG. 7 show exemplarily differences between the number and kind of layers used in the stacks at a glance.

[0051] FIG. 8 shows embodiments 800 of different layer stacks according to embodiments of the disclosure in a correct order. The dotted lines over inorganic layer(s) 130 symbolize that layer 130 may comprise a plurality of sublayers 200, 210, 220 which may form the inorganic layer 130. The number of sublayers for layer 130 is not restricted to the three layers shown and can be any number of layers necessary to achieve a desired characteristics of the optical reflector foil.

[0052] FIG. 9 shows 900 a multilayered plastic foil 150 which may be part of one of the layer stacks according to embodiments of the disclosure. The multilayered plastic foil 150 can be arranged directly on a metallic layer in this embodiment. Generally, metallic reflectors may be a cost-effective option of light recycler by LCD backlight unit (BLU) manufacturers. To ensure reliability, metal layers may usually be sandwiched within plastic foils by lamination, sacrificing color and reflectivity, especially color which is affecting LED options of the BLU. [0053] The multilayered plastic foil 150 may enable an optically-designable laminated reflector. The color can be designed to be favorable for BLU makers.

[0054] This may be achieved by providing a multi-layered plastic foil with a thickness of 1 to 100 um and more advantageously with a thickness of 5~50 um. The foil may comprise at least two composing polymers of different refractive indices. Further, the foil may comprise at least two composing layers stacked by methods such as co extrusion.

[0055] On the multi-layered plastic foil 150, at least one metallic reflecting layer 110 is formed e.g. by deposition methods such as PVD, the reflecting surface being on the multi-layered plastic side.

[0056] A plastic foil 120 with a thickness of 10 to 150 um, more advantageously with a thickness of 25-100 um, may be laminated on the formed surface of metallic layer 120 for chemical and mechanical protection. In some cases, it may be necessary to add an additional adhesion/barrier layer 140. The adhesion/barrier layer 140 may be optional and may be provided between the metallic layer 110 and the plastic layer 120.

[0057] This laminated-type of plastic foil may ensure reliability, with improved color performance and improved reflectivity. Further benefits are improved cost effectivity and a simpler manufacturing process. A multilayered plastic foil with more than 20 layers may be available by e.g. co-extrusion technology.

[0058] The term “adhesion/barrier” layer in the disclosure means that the layer may fulfill different objectives when arranged in the layer stack. Alternative terms for layer 140 may be “bonding layer” or “adhesion enhancement layer”. The adhesion/barrier layer 140 may e.g. comprise:

[0059] A glue-like adhesive layer (organic glue). This may be the case, if an adhesive (glue-like) function has to be achieved. An example may be the exemplary layer stack to the far left in FIG. 8. In this stack, adhesive layer may be a real organic adhesive used in a lamination machine (as e.g. see in Fig 13), which is configured to join two different plastic films on rolls of plastic films. [0060] The layer 140 may be denoted as an “adhesion/barrier” layer when arranged below the metal layer 110 as e.g. shown in the remaining layer stacks with the inorganic layer 130 in FIG. 8. Layer 140 below the metallic layer 110 may on one hand promote adhesion to the plastic layer 120 and, on the other hand, block, as a barrier, diffusivity through plastic layer 120. In other words, the layer 140 may fulfill two different functions when arranged at this position in the layer stacks: adhesion and barrier function (blocking of diffusion). The layer 140 may be deposited e.g. in a PVD process. Adhesion/barrier layer 140 may have a thickness below lOnm.

[0061] If a layer 140 may be arranged above the metallic layer 110, e.g. between inorganic layers 130 and metallic layer 110 as shown in the far right layer stack in FIG. 8, the layer 140 may serve as a pure adhesion layer with no barrier function, deposited e.g. in a PVD process. For this reason, the layer 140 may be denoted as an “adhesive/barrier layer. The adhesion/barrier layer 140 may have a thickness below lOnm.

[0062] FIGs 10 and 11, similar to FIGs 4 and 5, show examples 1000, 1100 of layer stacks with multi-layered plastic foils 150 in comparison with a layer stack known to the inventors (right side) which has only two layers. FIG. 10 uses a 19-layer multi layered foil, and FIG. 11 uses a 22-layer multi-layered foil on metallic layer 110. In both examples, transmission and reflection is improved compared to the stack known to the inventors.

[0063] FIG. 12 shows a reflection behaviour 1200 of a film according to embodiments of the disclosure and a film known to the inventors. Specifically in the wavelength range between 430 and 470nm, the reflection factor of the reflector film according to embodiments of the disclosure is surprisingly improved by the novel arrangement.

[0064] FIG. 13 shows, starting on the left side, a manufacturing 1300 of a multilayered foil 150. The foils may be first extruded by e.g. co-extrusion. A metallic layer 110 may be then deposited on the plastic foil 150. A plastic layer 120 is laminated on the stack to achieve mechanical stability. [0065] FIG. 14 discloses a method for manufacturing an optical reflector film according to one or more embodiments of the present disclosure. The order of the blocks may be not to be considered as fixed. Variations in the order of the blocks, the number of layers, their thickness and their sequence may be made in the production process.

[0066] According to an embodiment of the present disclosure, an optical reflector film may be provided. The optical reflector film comprises a stack of layers, wherein the stack comprises: at least a first plastic layer 120; in particular a plastic layer for mechanical stability of the stack. The stack may further comprise at least a first metallic layer 110. The metallic layer 110 may have a high reflection factor for visible light. The stack may further comprise a first layer, comprising one of a layer from a multi-layered plastic foil 150 or one or more layer of inorganic materials 130, 200, 210, 220.

[0067] In a further embodiment of the present disclosure, the optical reflector film comprises a stack of layers according to claim 1, wherein the stack may further comprise a second layer. This second layer may comprise a bonding layer 140.

[0068] In yet a further embodiment, which may be combined with other embodiments, the optical reflector film according to claim 1 may further comprise a third layer. The third layer may comprise an organic layer 100.

[0069] In yet a further embodiment, which may be combined with other embodiments, the optical reflector film may further comprise a fourth layer. The fourth layer may comprise an organic layer 100. This is, in a specific embodiment, the layer stack may comprise two layers of organic material 100.

[0070] In yet a further embodiment, which may be combined with other embodiments, the optical reflector film may further comprise a fifth layer. The fifth layer comprises an adhesion/barrier layer 140. This is, with this embodiment, two adhesion/barrier layers 140 in the stack may be possible.

[0071] Organic layers 100 may be made of e.g. materials like polyacrylates, polyurethane, melamine, polysiloxane, etc. The materials may be cross-linked and are mechanically very stable in nature and do not need protection. The combination of inorganic-organic layers may give superior protection to the metallic reflector layer 110. Organic layers may also be utilized for planarizing surfaces of a layer in the stack.

[0072] According to embodiments which can be combined with any other embodiments described herein, the multilayered plastic foil may comprise at least two composing layers of different refractive indices. A thickness of the multilayered plastic foil may be in a range of 5 to 50um.

[0073] According to embodiments which can be combined with any other embodiments described herein, the layer of inorganic materials 130 of the optical reflector film may further comprise at least two layers of different inorganic materials 200, 210, 220. In other words, the inorganic layer 130 may comprise “sub-layers” of different inorganic materials with different optical, mechanical, chemical characteristics. The inorganic layer 130 and the organic layer 100 protect the metallic reflector layer 110 (e.g. Ag) against moisture intrusion and, for example, oxidation.

[0074] The organic layer 100 may be a transparent coating of polyacrylates. Another material for the organic layer 100 may also be polyurethane or others. The used material has to provide a high transparency and has to be mechanically and/or chemically compatible with underlying and overlying layers. In particular the organic layer may be compatible with the metallic layer 110 and the inorganic layer 130.

[0075] One film exemplarily known to the inventors uses an organic layer 100 only to protect the Ag from e.g. oxidation (as shown in FIG. la). This solution may be not sufficient and also optically not tuneable, In particular, colour coordinates are not designable with only the organic layer.

[0076] Inorganic layers 130 on top of the organic layer 120 may be dual -functional since they provide a sufficient protection together with the organic layer to the metallic layer 110 against corrosion, and with proper optical design provides better optical properties (higher reflectance and good colour). The inorganic layers are highly transparent materials. [0077] In other words, a proper combination of inorganic and organic layers 100, 130 as provided in the present design of an optical reflector film, surprisingly not only provides an improved mechanical protection of the metallic layer 110 but also opens design space to tailor the reflector film’s optical properties.

[0078] The novel design of the presented embodiments of a layer stack also provides a better protection of the inorganic layer 130 during cutting. Inorganic materials, in particular inorganic oxides, are fragile (like glass) and if they are supported by a hard metal only, they tend to crack near the cutting edge when the film is cut. An organic support therefore provides a buffer with a certain elasticity to relax the cutting force. If a little crack is present on an edge, the inorganic layer 130 may remain intact and will provide certain protection to the metallic layer 110 (Ag), whereas the inorganic-only version as in FIG lb) loses protection completely along the cutted edge. A further advantage of the presented solution may be an enhanced optical characteristic, in particular variations in the color space, dependent on the combination and thickness of the organic and inorganic layers 130, 100.

[0079] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the layer of organic material 100 may be arranged between the at least one metallic layer 110 and the layer of inorganic material 130. An organic layer 100 as a support for the inorganic layer 130 may provide a buffer with a certain elasticity to relax a cutting force. Moreover, even if a little crack is present on an edge of the film, the inorganic layer 130 may remain intact and will provide certain protection to the metallic layer 110, whereas the prior art with only an inorganic layer, see FIG. lb) loses protection completely along the cut edge. The organic layer may comprise a transparent material, in particular a highly transparent material with a highest achievable transmission factor to let as much light radiation pass through as possible.

[0080] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the at least one metallic layer 110 may be arranged between the at least one layer of organic material 100 and the plastic layer 120 as may be further disclosed in FIG. 2 and FIG. 8. [0081] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, an additional adhesion/barrier layer 140 may be arranged between the plastic layer and the at least one metallic layer or between the organic layer 100 and the metallic layer 110 (see the right stack in FIG. 8). The additional layer 140 may be configured to enhance an adhesion between the at least one metallic layer 110 and the plastic layer 120.

[0082] Such an adhesion/barrier layer 140 may be used when the adhesion between the plastic foil/plastic layer 120 and the metal of the metallic layer 110 or also between other layer materials may be insufficient. An example may be Ag as a metallic layer 110 over PET, which may need a very thin layer of Ti or T1O2 or TiOx to ensure adhesion. The thin layer may bind well with both the metal and the plastic foil. An optional adhesion/barrier layer may also improve adhesion between an organic layer 100 and a metallic layer 110.

[0083] A specifically preferred embodiment of a layer stack according to one or more embodiments of the disclosure is e.g. shown in FIG. 8. , most right picture. The plastic layer 120 may have a preferred thickness of 75um; an adhesion/barrier layer 140 (e.g. TiOx) may have a thickness of 5nm; a metallic layer 110 (e.g. Ag) may have a thickness of 125nm; another adhesion/barrier layer 140, may have a thickness of 2nm (e.g. TiOx) and an inorganic layer 130, which may composed of a SiOx and a TiOx layer may have a thickness of 33nm for the SiOx layer and a thickness of 38nm in the TiOx layer.

[0084] This composition of a layer stack may only serve as an example and is not considered to generally restrict other layer stacks in thickness or sequence of layers. Optional layers of organic material 100 may be added between e.g. the plastic layer 120 and the adhesion/barrier layer 140 and/or on top of inorganic layer 130.

[0085] Of course, other materials which ensure an improved adhesion between the metallic layer 110 and the plastic layer 120 may also be used. FIGs. la) to lc), which show some reflector films known to the inventors, do not provide any adhesion/barrier layer 140 and may therefore suffer from the described drawbacks. [0086] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the second layer, which may comprise a adhesion/barrier layer 140, may be arranged between the at least one metallic layer 110 and the plastic layer 120. The second layer, comprising an adhesion/barrier layer 140, may also be arranged between the organic layer 100 and the at least one metallic layer 110.

[0087] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the third layer, which may comprise an organic layer 100, may be arranged between the layers of inorganic material(s) 130 and the metallic layer 110; or the third layer, comprising an organic layer 100, may alternatively be arranged between the plastic layer 120 and adhesion/barrier layer 140; or the third layer, comprising organic layer 100, may in another alternative be arranged between the plastic layer 120 and the metallic layer 110.

[0088] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the fourth layer, comprising an organic layer 100, may be arranged on the layer 130 of inorganic materials. The fourth layer may cover the layer stack in such a configuration. The fourth layer may serve as a planarization layer, in particular for the inorganic layer 130.

[0089] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the fifth layer, which may comprise an adhesion/barrier layer 140, may be arranged between inorganic layer 130 and metallic layer 110.

[0090] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the at least one metallic layer 110 may be arranged between the at least one layer of organic material 100 and the plastic layer 120.

[0091] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the additional adhesion/barrier layer 140 may comprise at least a material of the group Ti, TiOx, Cr, AZO or a glue-like adhesive material. The disclosure may be however not restricted to this group of materials. Other materials which may serve as adhesion/barrier layer 140, to improve contact between layers like plastic layer 120, metallic layer 110, organic layer 100 (FIG. 8) may be used. Adhesion/barrier layer 140 can be applied by laminating or by a PVD method, depending on the used layer stack. In particular, in the left layer stack in FIG. 8 with the multilayered foil, the adhesion/barrier layer 140 may be a glue-like laminated bonding layer, e.g. a real organic adhesive used in a lamination machine as shown in FIG. 13. The remaining stacks in FIG. 8 may have adhesion/barrier layers (optional), which comprise very thin inorganic materials, advantageously applied during a PVD process.

[0092] An exemplary layer stack, which may represent an embodiment of a disclosed optical reflector film stack, may have a composition like: PET as a plastic layer 120. An (optional) Ti adhesion/barrier layer 140 deposited on the plastic layer 120; a metallic layer (e.g. Ag) deposited either directly on the plastic layer 120 or on the (optional) adhesion/barrier layer 140; an organic layer 100 (e.g. from polyacrylate) deposited on the metallic layer 110; an inorganic layer 130 (e.g from SiCk or TiCk or two or more layers with these materials).

[0093] PET (Polyethylene Terephthalate) may serve as the plastic foil 120, (Ti) may serve as the optional adhesion promoter (adhesion/barrier layer 140). Ag may serve as the metallic layer 110 (the reflecting metal).

[0094] Polyacrylate may be used in the organic layer 100 for relaxation, protection and providing a flat surface (planarization layer) for the subsequent inorganic layers 130 to grow well, SiCk and TiCk (or generally materials from TiOx/SiCk) for both protection and optical property enhancement. Optionally, the inorganic layer 130 comprises several stacked sub layers from different inorganic materials.

[0095] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, a thickness of the additional adhesion/barrier layer may be smaller than a thickness of the plastic layer or the at least one metallic layer. In particular, the thickness of the additional adhesion/barrier layer may be very thin, in particular, the thickness of the adhesion/barrier layer 140 may be below lOnm. [0096] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the at least one metallic layer 110 may comprise a material having a reflection factor greater than 70% in a wave-length of light between 350 and 800nm, e.g. Ag, Al, Ag alloy. It may be advantageous if the wave- length of visible light is covered by the high reflectance. In other words, it may be a goal that the highest reflectance covers the band with visible light (380nm to 780nm).

[0097] FIG. 6 shows the reflection factor of a reference optical reflector film vs. an example optical reflector film according to the present disclosure. The reflection factor of the film according to embodiments of the present disclosure reflects an amount of incoming light with a reflection factor of more than 94% in the wavelength between 380nm to 780nm. The reference film according to a known structure reflects less amount of light.

[0098] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the material of the inorganic layer 130 may be a transparent material, in particular a highly transparent material with a highest achievable transmission factor to let as much light radiation pass through as possible.

[0099] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the plastic material of the plastic layer 120 may be at least one of the group PC (Poly Carbonate), PEN (polyethylenenaphtalat), PET (polyetyleneterephtalat), PI (polyimid).

[00100] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the at least two inorganic layers (“sub-layers” 200, 210, 220) which form the inorganic layer 130 can be selected of a group S1O2, T1O2, >205, ZrCh, ZnCh, AI2O3, Ta20s, Y2O3, SnCh, a ZnO:Al composition. The materials can be in a doped form, in a pure form, off-stoichiometric, on-stoichiometric or any combination.

[00101] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the thickness and/or composition of the inorganic and/or organic layers 130, 100 can be configured so that a color of reflection can be adapted to have a predetermined characteristic.

[00102] In particular, thickness, material and/or composition of the inorganic/organic layers 130, 100 can be chosen in a way that the reflected light may have a predetermined color characteristic. The color characteristic may influence the color of a picture displayed on the display panel which may be equipped with the reflector film/foil. By varying composition and thicknesses of organic and inorganic layers 100, 130, a reflecting color may be tuned according to customer needs or market requirement.

[00103] For example, a design may depend on a desired goal: If the luminance of a Back Light Unit (BLU) is affected, reflectivity of optical film should be high. Combination and specific relation of Ag + SiOx/TiOx may further enhance visible reflectivity.

[00104] If chromaticity of the Back Light Unit is affected, color coordinates of the reflective film may be tuned. Adjusting the relation of SiOx/TiOx may be used to e.g. pull up blue light reflectivity.

[00105] SiOx/TiOx as a moisture barrier may enhance reliability of the optical reflector film.

[00106] Ti, TiOx as a thin adhesion (bonding) layer may enhance Ag bonding onto the base film and therefore improve reliability of the optical reflector film. [00107] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the metallic layer may be of the group Ag, Al, Ag alloy, but may be not restricted to that. Other highly reflective metallic materials are usable for the purpose.

[00108] According to embodiments, an optical reflector film comprising a stack of layers is disclosed, the layers may be arranged in a sequence: a plastic layer 120; a metallic layer 110; a layer of a plastic foil 150 or a layer of inorganic materials 130, wherein the plastic foil 150 is a multilayered plastic foil and wherein the layer of inorganic materials 130 comprises one or more sublayers 200, 210, 220 of different inorganic materials.

[00109] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, an adhesion/barrier layer 140 may be arranged between the plastic layer 120 and the metallic layer 110.

[00110] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, an optical reflector film comprising a stack of layers is disclosed. The layers in the stack may be arranged in a sequence: a plastic layer 120; a metallic layer 110; a layer of inorganic materials 130, wherein the layer of inorganic materials 130 may comprise one or more sublayers 200, 210, 220 of different inorganic materials.

[00111] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the optical reflector film according to other embodiments may further comprise an organic layer 100, arranged between the layer of inorganic materials 130 and the metallic layer 110 and/or an adhesion/barrier layer 140 which is arranged between the plastic layer 120 and the metallic layer 110.

[00112] According to embodiments of the optical reflector film which can be combined with any other embodiments described herein, the optical reflector film may further comprise a first organic layer 100, arranged on the layer of inorganic materials 130 and/or a first adhesion/barrier layer 140 which may be arranged between the layer of inorganic materials 110 and the metallic layer 110 and/or a second organic layer 100 and/or a second adhesion/barrier layer 140, wherein the adhesion/barrier layer 140 may be arranged adjacent to the metallic layer 110 and/or the organic layer 100 may be arranged adjacent to the plastic layer 120; and/or the adhesion/barrier layer 140 may be arranged between the metallic layer 110 and the organic layer 100.

[00113] An. exemplary layer stack as shown in FIG. 8 may comprise:

[00114] A plastic foil 120; an adhesion/barrier layer 140 arranged on the plastic layer 120; a metallic layer 110 arranged on the adhesion/barrier layer; a multilayered plastic foil layer 150, arranged on the metallic layer 110. [00115] Another exemplary layer stack as shown in FIG. 8 may comprise:

[00116] A plastic foil 120; an adhesion/barrier layer 140 arranged on the plastic layer 120; a metallic layer 110 arranged on the adhesion barrier layer 140 and an inorganic layer 130 (comprising one or more inorganic sub-layers 200, 210, 220) arranged on the metallic layer 110.

[00117] Another exemplary layer stack as shown in FIG. 8 may comprise:

[00118] A plastic layer 120; an adhesion/barrier layer 140 arranged on the plastic layer 120, a metallic layer 110, arranged on the adhesion/barrier layer 110; an organic layer 100, arranged on the metallic layer 110 and an inorganic layer 130 (comprising one or more inorganic sub-layers 200, 210, 220), arranged on the organic layer 100.

[00119] Another exemplary layer stack as shown in FIG. 8 may comprise:

[00120] A plastic layer 120, an organic layer 100, arranged on the plastic layer 120; an adhesion/barrier layer 140, arranged on the organic layer 100; a metallic layer 110, arranged on the adhesion/barrier layer 140; an adhesion/barrier layer 140, arranged on the metallic layer 110 (the metallic layer 110 is “sandwiched” between the adhesion/barrier layers 140); an inorganic layer 130 (comprising one or more inorganic sub-layers 200, 210, 220), arranged on the adhesion/barrier layer 140 and an organic layer 100, arranged on the inorganic layer 130.

[00121] According to embodiments of the optical reflector film, a method of manufacturing a reflective film according to previous embodiments is disclosed (FIG. 14).

[00122] The method may comprise: providing a plastic layer 120 (performed in block 1400); depositing a metallic layer 110 on the plastic layer 120 (performed in block 1410); depositing an organic layer 100 on the metallic layer 110 (performed in block 1420) and depositing an inorganic layer 130 on the organic layer 100 (performed in block 1430).

[00123] According to embodiments of the method of manufacturing an optical reflector film which can be combined with any other embodiments described herein, the method may further comprise depositing an additional adhesion/barrier layer 140 between the plastic layer and the metallic layer (performed in optional block 1440). Method block 1440 may be advantageously performed.

[00124] A further optional block may be performed concerning method block 1430. In this method block, a plurality of inorganic layers (performed in method blocks 1450, 1460, 1470) may be deposited to form one inorganic layer 130.

[00125] A further block, allowing for depositing an organic layer 100 on the inorganic layer 130, may be provided in the method.

[00126] Yet a further block allowing for arranging a further adhesion/barrier layer 140 between the inorganic layer 130 and the metallic layer 110 may be provided in the method.

[00127] The order of the blocks shown may be not to be considered as fixed and therefore not restrictive. Variations in the order of the blocks may be made in the production process. This in particular may concern block 1440, in which the optional adhesion/barrier layer 140, to improve the adhesion between organic layer 100 and metallic layer 110, may be arranged to the layer stack and also block 1430, in which “subday ers” 200, 210, 220” of different inorganic materials are deposited, to form one inorganic layer 130. The disclosed method may be adapted such that it allows for manufacturing optical reflector films as exemplarily shown in FIG. 8. One or more of the layer combinations as shown in FIG.7 may be used. [00128] According to a further embodiment of the present disclosure, an optical display with an optical reflector film according to one or more embodiments of the present disclosure is disclosed. The reflective film may be applied on the back side of the light guide plate in the backlight of an LCD display.

[00129] The presented optical reflector film can be applied to the backlight arrangement of non-emissive displays (displays in which the picture generating elements (“pixels”) have no self-luminous characteristics). The provided optical reflector film helps to enhance the brightness of a picture, displayed on the panel, by reflecting the light from backlight /-edgelight sources attached to the panel through the panel towards an observer.

[00130] The optical reflector film/foil reflects parts of the light from the light sources which are not directed towards the observer and would be otherwise lost. [00131] The optical reflector film comprises a metallic reflector layer, arranged/deposited on a plastic layer. The plastic layer in particular comprises PET. Other plastics like PC, PEN or PI are also an option.

[00132] The metallic layer 110 may be covered with an organic material layer 100 and the organic layer 100 material may be covered with a layer 130 of an inorganic material.

[00133] The combination of organic and inorganic layers protects the metallic reflector layer against corrosion and scratches during handling. The organic layer has a formulation design that may provide a good adhesion on metal. For the inorganic layer, typically two or more inorganic layers (“sub layers”) may be needed for improved optical performance. The materials may be selected from S1O2, T1O2, Nb20s, ZrCh, ZnCh, AI2O3, Ta2C>5, Y2O3, SnCh, NbxOy.

[00134] The presented reflector film surprisingly may allow for a better mechanical stability, e.g. during manufacturing steps, due to a combination of organic and inorganic layers over a metallic layer. [00135] Further and more surprisingly, contrary to currently available prior art films, the combination of inorganic and organic layers over the metallic reflector layer further may allow for adapting the color of reflected light and therefore influencing a picture, displayed on a display which may be equipped with the disclosed optical reflector film, to specific requirements. [00136] The combination of at least one organic layer and inorganic layer(s) on a metallic layer may alternatively be replaced by laminated plastic foil. This alternative arrangement may solve a demand for an optically-designable laminated reflector. The color of this laminated reflector may be designed according to the needs of the manufacturers of Back Light Units (BLU) for optical displays.

[00137] While the foregoing may be directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

[00138] In particular, this written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the described subject-matter, including making and using any devices or systems and performing any incorporated methods. While various specific embodiments have been disclosed in the foregoing, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope is defined by the claims, and other examples are intended to be within the scope of the claims if the claims have structural elements that do not differ from the literal language of the claims, or if the claims include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. An optical reflector film comprising a stack of layers, wherein the stack comprises: at least a first metallic layer (110); at least a first plastic layer (120); a first layer, comprising one of a layer from a multi-layered plastic foil (150) or one or more layers of inorganic materials (130, 200, 210, 220).

2 The optical reflector film comprising a stack of layers according to claim 1, wherein the stack further comprises: a second layer, comprising an adhesion/barrier layer (140);

3. The optical reflector film according to claims 1 or 2, further comprising a third layer which comprises an organic layer (100).

4. The optical reflector film according to claim 3, further comprising a fourth layer which comprises an organic layer (100).

5. The optical reflector film according to claim 4, further comprising a fifth layer which comprises an adhesion/barrier layer (140).

6. The optical reflector film according to any of the preceding claims, wherein the multi-layered plastic foil (150) comprises at least two composing polymers of different refractive indices.

7. The optical reflector film according to any of the preceding claims, wherein the one or more layer of inorganic material (130) comprises at least two layers (200, 210, 220) of different inorganic materials.

8. The optical reflector film according to any of the preceding claims, wherein the second layer, comprising an adhesion/barrier layer (140) can be arranged between the at least one metallic layer (110) and the plastic layer (120); or the second layer, comprising an adhesion/barrier layer (140) can be arranged between the organic layer (100) and the at least one metallic layer (110).

9. The optical reflector film according to any of the preceding claims, wherein the third layer, comprising the organic layer (100), is arranged between the layers of inorganic material(s) (130) and the metallic layer (110); or, the third layer, comprising the organic layer (100), is arranged between the plastic layer (120) and the adhesion/barrier layer (140); or the third layer, comprising the organic layer (100), is arranged between the plastic layer (120) and the metallic layer (110).

10. The optical reflector film according to any of the preceding claims, wherein the fourth layer, comprising an organic layer (100), is arranged on the layer (130) of inorganic materials.

11. The optical reflector film according to any of the preceding claims, wherein the fifth layer, comprising the adhesion/barrier layer (140), is arranged between the inorganic layer (130) and the metallic layer (110).

12. The optical reflector film according to any of the preceding claims, wherein the at least one metallic layer (110) is arranged between the at least one layer of organic material (100) and the plastic layer (120).

13. The optical reflector film according to any of the preceding claims, wherein the additional adhesion/barrier layer (140) comprises a material of the group Ti, TiOx, Cr, AZO, or a glue-like adhesive material.

14. The optical reflector film according to any of the preceding claims, wherein a thickness of at least one of the additional adhesion/barrier layer (140) is smaller than a thickness of the plastic layer (120) or the at least one metallic layer (110).

15. The optical reflector film according to any of the preceding claims, wherein a thickness of the additional adhesion/barrier layer (140) is smaller than 10 nm.

16. The optical reflector film according to any of the preceding claims, wherein the at least one metallic layer (110) comprises a material having a reflection factor greater than 70% in a wave-length of light between 350nm and 800nm.

17. The optical reflector film according to any of the previous claims, wherein the at least one metallic layer (110) comprises at least one of the group Ag, Al, Ag alloy.

18. The optical reflector film according to any of the preceding claims, wherein the material of the inorganic layer (130) is a transparent material.

19. The optical reflector film according to any of the preceding claims, wherein the plastic material of the plastic film (120) is one of the group: PC (poly carbonate), PEN (polyethylenenaphtalat), PET (polyetyleneterephtalat), PI (polyimid).

20. The optical reflector film according to any of the preceding claims, wherein the at least two inorganic layers (200, 210, 220) can be selected of a group SiOx, TiOx, >2q5, ZrCE, ZnC , AI2O3, Ta20s, Y2O3, SnCh, ZnO:Al in any combination and sequence, wherein the materials can be doped or pure and/or off- or on stoichiometric.

21. The optical reflector film according to any of the preceding claims, wherein thickness and/or composition of the inorganic (130) and/or organic layers (100) can be adapted so that a color of reflection can be adapted to have a predetermined characteristic.

22. An optical reflector film comprising a stack of layers, the layers being in a sequence: a plastic layer (120); a metallic layer (110); a layer of a plastic foil (150) or a layer of inorganic materials (130), wherein the plastic foil (150) is a multilayered plastic foil and wherein the layer of inorganic materials (130) comprises one or more sublayers (200, 210, 220) of different inorganic materials.

23. The optical reflector film according to claim 22, wherein an adhesion/barrier layer (140) is arranged between the plastic layer (120) and the metallic layer (110).

24. An optical reflector film comprising a stack of layers, the layers being in a sequence: a plastic layer (120); a metallic layer (110); a layer of inorganic materials (130), wherein the layer of inorganic materials (130) comprises one or more sublayers (200, 210, 220) of different inorganic materials.

25. The optical reflector film according to claim 24, further comprising an organic layer (100), arranged between the layer of inorganic materials (130) and the metallic layer (110) and/or an adhesion/barrier layer (140) which is arranged between the plastic layer (120) and the metallic layer (110).

26. The optical reflector film according to claim 24, further comprising a first organic layer (100), arranged on the layer of inorganic materials (130); and/or a first adhesion/barrier layer (140) which is arranged between the layer of inorganic materials (110) and the metallic layer (110); and/or a second organic layer (100) and/or a second adhesion/barrier layer (140), wherein the adhesion/barrier layer (140) is arranged adjacent to the metallic layer (110); and/or the organic layer (100) is arranged adjacent to the plastic layer (120); and/or the adhesion/barrier layer (140) is arranged between the metallic layer (110) and the organic layer (100).

27. An optical display with an optical reflector film according to any of the preceding claims.