PATENT DOCUMENT

Publication Number: US-9618669-B2
Application Number: US-201314075419-A
Country: US
Kind Code: B2

Title: Electronic device display with polarizer windows

Abstract:
Electronic devices may be provided with displays that have polarizers. A polarizer may have a polymer layer that has a portion covered with a dichroic dye to form a polarized region and a portion that is free of dichroic dye to form an unpolarized region. The unpolarized region may be formed by masking the polymer layer during a dye coating process. Masks may be formed from polymers. The shape of the mask may define the shape of the unpolarized region. The mask may be left in place within the polarizer or may be removed from the polarizer during fabrication. Unpolarized regions may also be formed by light bleaching, chemical bleaching, and material removal techniques. Bleached areas may be chemically stabilized. A moisture barrier layer may be incorporated into the polarizer to help prevent the unpolarized region from reverting to a polarized state.

Claims:
What is claimed is: 
     
       1. A display, comprising:
 display layers; and 
 a polarizer layer on the display layers, wherein the polarizer layer has first and second opposing surfaces and a layer of polarizing material between the first and second opposing surfaces, wherein the layer of polarizing material has an unpolarized region, wherein the polarizer layer includes masking material between the first and second opposing surfaces that overlaps and is aligned with the unpolarized region, and wherein the layer of polarizing material has a polarized region that is free of the masking material. 
 
     
     
       2. The display defined in  claim 1  further comprising dichroic dye in the polarized region. 
     
     
       3. The display defined in  claim 2  wherein the dichroic dye comprises iodine. 
     
     
       4. The display defined in  claim 3  wherein the masking material comprises a polymer. 
     
     
       5. The display defined in  claim 4  wherein the layer of polarizing material comprises a polyvinyl alcohol layer coated by the dichroic dye in the polarized region and covered with the masking material in the unpolarized region. 
     
     
       6. The display defined in  claim 5  wherein the display layers include a color filter layer, a thin-film transistor layer, and a layer of liquid crystal material between the color filter layer and the thin-film transistor layer. 
     
     
       7. A method, comprising:
 forming a patterned mask on an unpolarized polymer layer; 
 coating the unpolarized polymer layer and the patterned mask with a dye, wherein coating the unpolarized polymer layer with the dye forms a polarized region from a first portion of the unpolarized polymer layer that does not overlap the patterned mask while forming an unpolarized region from a second portion of the unpolarized polymer layer that does overlap the patterned mask; and 
 removing the patterned mask from the unpolarized region. 
 
     
     
       8. The method defined in  claim 7  wherein the unpolarized polymer layer has opposing first and second surfaces, wherein coating the unpolarized polymer layer and the patterned mask comprises applying a coating to the first surface, and wherein the method further comprises attaching a film to the second surface before coating the unpolarized polymer layer and the patterned mask. 
     
     
       9. The method defined in  claim 8  further comprising attaching additional layers to the unpolarized polymer layer. 
     
     
       10. The method defined in  claim 9  further comprising removing the film before attaching the additional layers. 
     
     
       11. The method defined in  claim 10  wherein attaching the additional layers comprises attaching a birefringent compensation film. 
     
     
       12. A method, comprising:
 forming a patterned mask on a polymer layer; 
 coating the polymer layer and the patterned mask with a dye to form a polarized region that does not include the patterned mask and an unpolarized region covered by the patterned mask; and 
 attaching an additional layer to the polymer layer and the patterned mask such that the patterned mask is interposed between the additional layer and the polymer layer. 
 
     
     
       13. The method defined in  claim 12  wherein the polymer layer has opposing first and second surfaces, wherein coating the polymer layer and the patterned mask comprises applying a coating to the first surface, and wherein the method further comprises attaching a film to the second surface before coating the polymer layer and the patterned mask. 
     
     
       14. The method defined in  claim 13  further comprising attaching compensation layers to the polymer layer. 
     
     
       15. The method defined in  claim 14  further comprising removing the film before attaching the compensation layers. 
     
     
       16. The method defined in  claim 15  wherein attaching the compensation layers comprises attaching a birefringent compensation film. 
     
     
       17. The method defined in  claim 12 , wherein the additional layer is a layer of adhesive. 
     
     
       18. The method defined in  claim 17 , wherein the layer of adhesive attaches a tri-acetyl cellulose layer to the polymer layer and the patterned mask.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with displays. 
     Electronic devices often include displays. For example, cellular telephones, computers, and televisions have displays. 
     It can be challenging to mount light-based electronic components such as cameras and sensors in devices with displays. Some devices have large inactive display areas covered with protective bezels. In this type of device, a component such as a camera can be mounted under a camera window in the bezel. Although this type of arrangement will allow the camera to operate satisfactorily, the use of the bezel on the display may be unattractive and bulky. More compact and aesthetically appealing display designs are possible by mounting components in alignment with windows formed directly within an inactive border of the display. Such windows may, however, have unsightly edges or may contain polarizer material that can interfere with component performance. 
     It would therefore be desirable to be able to provide electronic devices with improved arrangements for accommodating components in displays. 
     SUMMARY 
     An electronic device may be provided with a display. The display may have a polarizer. The polarizer may have an unpolarized region. The unpolarized region may overlap some or all of the inactive area in the display. The unpolarized region may, for example, overlap text, graphics, or other content in the inactive area or may form part of a transparent window for a light-based component such as a camera, light sensor, or light emitting component. 
     A display polarizer may have a polymer layer. The polymer layer may have a portion that is covered with a dichroic dye to form a polarized region and may have a portion that is free of dichroic dye and that therefore forms an unpolarized region. 
     The shape of the unpolarized region may be defined by masking the polymer layer during the dye coating process. Masks may be formed from polymers such as photoresist. A mask may be left in place within a polarizer or may be removed from the polarizer during fabrication. Unpolarized regions may also be formed by light bleaching, chemical bleaching, and polarizer material removal techniques such as mechanical and laser cutting techniques. Bleached areas may be chemically stabilized. Cut areas may be backfilled with index matching polymer. A moisture barrier layer may be incorporated into the polarizer to improve reliability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a laptop computer with display structures in accordance with an embodiment. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a handheld electronic device with display structures in accordance with an embodiment. 
         FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer with display structures in accordance with an embodiment. 
         FIG. 4  is a perspective view of an illustrative electronic device such as a display for a computer or television with display structures in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of an illustrative display in accordance with an embodiment. 
         FIG. 6A  is a front view of an illustrative display in accordance with an embodiment. 
         FIG. 6B  is a cross-sectional side view of a polarizer window in alignment with a light-based component in accordance with an embodiment. 
         FIG. 7  is a front view of an illustrative display showing how polarizer windows of various shapes may be used in a display in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative polarizer in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of a polarizer layer that is being exposed to light to form an unpolarized region in accordance with an embodiment. 
         FIG. 10  is a diagram showing how the unpolarized window region of  FIG. 9  may be chemically treated in accordance with an embodiment. 
         FIG. 11  is a diagram of a system being used to form a display having a polarizer layer with an unpolarized region in accordance with an embodiment. 
         FIGS. 12, 13, 14, 15, and 16  are cross-sectional views of structures produced by using a patterned mask to form a display with a polarizer window in accordance with an embodiment. 
         FIGS. 17, 18, 19, 20, and 21  are cross-sectional views of structures produced by using a removable patterned mask to form a display with a polarizer window in accordance with an embodiment. 
         FIG. 22  shows how a polarizer window may be formed by removing polarizer material and filling the resulting void with transparent material in accordance with an embodiment. 
         FIG. 23  is a flow chart of steps involved in forming an unpolarized region on a polarizer using chemical bleaching operations in accordance with an embodiment. 
         FIG. 24  is a flow chart of illustrative steps involved in forming an unpolarized region on a polarizer using masking techniques in accordance with an embodiment. 
         FIG. 25  is a cross-sectional side view of a polarizer that includes a moisture barrier to help enhance the reliability of an unpolarized region in accordance with an embodiment. 
         FIG. 26  is a cross-sectional side view of an illustrative polarizer in which a moisture barrier has been formed adjacent to a polarizer film in accordance with an embodiment. 
         FIG. 27  is a cross-sectional side view of an illustrative polarizer in which a polymer layer has been interposed between a moisture barrier layer and a polarizer film in accordance with an embodiment. 
         FIG. 28  is a cross-sectional side view of an illustrative polarizer in which a moisture barrier has been formed on top of a protective film in the polarizer in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with displays. The displays may include polarizers. To create an appealing appearance for the display, the display may be mounted in a housing in a way that minimizes the use of bulky bezel structures. Transparent unpolarized regions may be formed in an inactive border of the display. The unpolarized regions may be formed using chemical bleaching of polarizer material, light bleaching, polarizer film removal, masking techniques, other fabrication techniques, or combinations of these techniques. Chemical stabilization and moisture barrier structures may help enhance reliability. 
     Illustrative electronic devices of the types that may be provided with displays having polarizers with unpolarized regions are shown in  FIGS. 1, 2, 3, and 4 . 
     Electronic device  10  of  FIG. 1  has the shape of a laptop computer and has upper housing  12 A and lower housing  12 B with components such as keyboard  16  and touchpad  18 . Device  10  has hinge structures  20  (sometimes referred to as a clutch barrel) to allow upper housing  12 A to rotate in directions  22  about rotational axis  24  relative to lower housing  12 B. Display  14  is mounted in housing  12 A. Upper housing  12 A, which may sometimes be referred to as a display housing or lid, is placed in a closed position by rotating upper housing  12 A towards lower housing  12 B about rotational axis  24 . 
       FIG. 2  shows an illustrative configuration for electronic device  10  based on a handheld device such as a cellular telephone, music player, gaming device, navigation unit, or other compact device. In this type of configuration for device  10 , housing  12  has opposing front and rear surfaces. Display  14  is mounted on a front face of housing  12 . Display  14  may have an exterior layer that includes openings for components such as button  26  and speaker port  28 . 
     In the example of  FIG. 3 , electronic device  10  is a tablet computer. In electronic device  10  of  FIG. 3 , housing  12  has opposing planar front and rear surfaces. Display  14  is mounted on the front surface of housing  12 . As shown in  FIG. 3 , display  14  has an opening to accommodate button  26 . 
       FIG. 4  shows an illustrative configuration for electronic device  10  in which device  10  is a computer display, a computer that has an integrated computer display, or a television. Display  14  is mounted on a front face of housing  12 . With this type of arrangement, housing  12  for device  10  may be mounted on a wall or may have an optional structure such as support stand  30  to support device  10  on a flat surface such as a table top or desk. 
     Display  14  may be a liquid crystal display, an organic light-emitting diode display, a plasma display, an electrophoretic display, an electrowetting display, a display using other types of display technology, or a display that includes display structures formed using more than one of these display technologies. Display  14  may include one or more polarizers. For example, an organic light-emitting diode display may include a circular polarizer, a liquid crystal display may have upper and lower polarizers, etc. Configurations for display  14  in which display  14  is a liquid crystal display are sometimes described herein as an example. This is merely illustrative. Display  14  may be formed using any suitable type of display technology. 
     A cross-sectional side view of an illustrative configuration for display  14  of device  10  (e.g., a liquid crystal display for the devices of  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 4  or other suitable electronic devices) is shown in  FIG. 5 . As shown in  FIG. 5 , display  14  may include backlight structures such as backlight unit  42  for producing backlight  44 . During operation, backlight  44  travels outwards (vertically upwards in dimension Z in the orientation of  FIG. 5 ) and passes through display pixel structures in display layers  46 . This illuminates any images that are being produced by the display pixels for viewing by a user. For example, backlight  44  may illuminate images on display layers  46  that are being viewed by viewer  48  in direction  50 . 
     Display layers  46  may be mounted in chassis structures such as a plastic chassis structure and/or a metal chassis structure to form a display module for mounting in housing  12  or display layers  46  may be mounted directly in housing  12  (e.g., by stacking display layers  46  into a recessed portion in housing  12 ). 
     Display layers  46  may include a liquid crystal layer such a liquid crystal layer  52 . Liquid crystal layer  52  may be sandwiched between display layers such as display layers  58  and  56 . Layers  56  and  58  may be interposed between lower (innermost) polarizer layer  60  and upper (outermost) polarizer layer  54 . 
     Layers  58  and  56  may be formed from transparent substrate layers such as clear layers of glass or plastic. Layers  56  and  58  may be layers such as a thin-film transistor layer and/or a color filter layer. Conductive traces, color filter elements, transistors, and other circuits and structures may be formed on the substrates of layers  58  and  56  (e.g., to form a thin-film transistor layer and/or a color filter layer). Touch sensor electrodes may also be incorporated into layers such as layers  58  and  56  and/or touch sensor electrodes may be formed on other substrates. 
     With one illustrative configuration, layer  58  may be a thin-film transistor layer that includes an array of thin-film transistors and associated electrodes (display pixel electrodes) for applying electric fields to liquid crystal layer  52  and thereby displaying images on display  14 . Layer  56  may be a color filter layer that includes an array of color filter elements for providing display  14  with the ability to display color images. If desired, layer  58  may be a color filter layer and layer  56  may be a thin-film transistor layer. 
     During operation of display  14  in device  10 , control circuitry (e.g., one or more integrated circuits on a printed circuit) may be used to generate information to be displayed on display  14  (e.g., display data). The information to be displayed may be conveyed to a display driver integrated circuit such as circuit  62  using a signal path such as a signal path formed from conductive metal traces in a rigid or flexible printed circuit such as printed circuit  64  (as an example). 
     Backlight structures  42  may include a light guide plate such as light guide plate  78 . Light guide plate  78  may be formed from a transparent material such as clear glass or plastic. During operation of backlight structures  42 , a light source such as light source  72  may generate light  74 . Light source  72  may be, for example, an array of light-emitting diodes. 
     Light  74  from light source  72  may be coupled into edge surface  76  of light guide plate  78  and may be distributed in dimensions X and Y throughout light guide plate  78  due to the principal of total internal reflection. Light guide plate  78  may include light-scattering features such as pits or bumps. The light-scattering features may be located on an upper surface and/or on an opposing lower surface of light guide plate  78 . 
     Light  74  that scatters upwards in direction Z from light guide plate  78  may serve as backlight  44  for display  14 . Light  74  that scatters downwards may be reflected back in the upwards direction by reflector  80 . Reflector  80  may be formed from a reflective material such as a layer of white plastic or other shiny materials. 
     To enhance backlight performance for backlight structures  42 , backlight structures  42  may include optical films  70 . Optical films  70  may include diffuser layers for helping to homogenize backlight  44  and thereby reduce hotspots, compensation films for enhancing off-axis viewing, and brightness enhancement films (also sometimes referred to as turning films) for collimating backlight  44 . Optical films  70  may overlap the other structures in backlight unit  42  such as light guide plate  78  and reflector  80 . For example, if light guide plate  78  has a rectangular footprint in the X-Y plane of  FIG. 5 , optical films  70  and reflector  80  may have a matching rectangular footprint. 
     As shown in  FIG. 6A , display  14  may be characterized by an active area such as active area AA. Active area AA may include an array of display pixels  90 . Display pixels  90  may be used in displaying images to viewer  48  ( FIG. 5 ) during operation of device  10 . An inactive border region such as inactive area IA may surround the periphery of active area AA. For example, in a configuration of the type shown in  FIG. 6A  in which active area AA has a rectangular shape surrounded by four peripheral edges, inactive region IA may have the shape of a rectangular ring that runs along each of the four peripheral edges of active area AA and thereby surrounds active area AA. Displays with different active area and inactive area shapes may be used if desired. The configuration of  FIG. 6A  is merely illustrative. 
     Device  10  may include light-based components such as a camera (digital image sensor), an ambient light sensor, a light-based proximity sensor (e.g., a sensor having a light emitter and corresponding light detector), status indicator lights, etc. These components may be mounted under display  14  in inactive area IA. Transparent window regions may be formed in display  14  to accommodate the light-based components. The window regions may be free from polarized material. For example, upper polarizer  54  of  FIG. 5  may be provided with transparent regions that are unpolarized and that therefore exhibit high transmittance (e.g., 80% or more, 90% or more, etc.). The electrical components that are overlapped by inactive area IA can be mounted in alignment with these unpolarized regions. 
     A cross-sectional side view of a portion of an illustrative display that has a polarizer with an unpolarized window is shown in  FIG. 6B . As shown in  FIG. 6B , display  14  may include display layers  46  (see, e.g., display layers  46  of  FIG. 5 ). Display layers  46  may include display layers  46 ′ (e.g., a color filter layer, a thin-film transistor layer, a lower polarizer, etc.). Display layers  46  may also include upper polarizer  54 . Polarizer  54  may have polarized regions such as regions  100  and an unpolarized region such as region  96  that is free of polarizing material and that therefore may form a transparent window for display  14 . Light-based component  92  (i.e., a camera, a light sensor, a light emitter, or other component) may be mounted in alignment with unpolarized region  96 . For example, component  92  may be mounted under region  96  so that incoming and/or outgoing light  98  that is associated with the operation of component  92  may pass through region  96 . If desired, light  98  may pass through one or more transparent layers in display layers  46 ′. For example, glass layers, plastic layers, or other layers of material among layers  46 ′ may be interposed between component  92  and polarizer  54 . If desired, an opening such as opening  94  may be formed in some or all of layers  46 ′ (e.g., to allow component  92  to be mounted closer to polarizer  54 ). 
     In some displays, it may be desirable to incorporate a layer of opaque masking material around the periphery of the display. For example, some or all of inactive area IA of display  14  ( FIG. 6A ) may be provided with a layer of black ink, white ink, or other opaque masking material to hide internal device components from view by a user. When forming windows for light-based components, openings may be formed in the opaque masking material in alignment with unpolarized regions. If desired, unpolarized regions may also be formed over patterned or unpatterned opaque masking material or other opaque structures. For example, unpolarized regions such as region  96  of  FIG. 6B  may be formed over a logo in inactive area IA. 
       FIG. 7  is a top view of display  14  showing illustrative patterns of unpolarized regions  96  that may be optionally formed within polarizer  54  (i.e., in inactive area IA of display  14 ). As shown in  FIG. 7 , unpolarized regions  96  may include circular regions such as camera or sensor window  96 - 1 , rectangular regions such as region  96 - 2  (e.g., a rectangular window for a proximity sensor, ambient light sensor, or status indicator light), arrays of multiple smaller unpolarized region such as array  96 - 3  (e.g., an array of circular regions or rectangular regions in which the density of unpolarized regions in the array controls overall light transmittance), text, graphics, logos, or other decorative or informative content such as logo  96 - 4 , and border regions running along one, two, three, or four of the peripheral edges of display  14  such as illustrative right-hand border  96 - 5 . 
     Unpolarized regions  96  of polarizer layer  54  may overlap transparent window openings through display layers  46 ′ (e.g., to accommodate light  98  associated with component  92 ) and/or may overlap opaque layers of material (e.g., in association with creating a logo, an opaque border, etc.). 
     A cross-sectional side view of an illustrative polarizer for display  14  is shown in  FIG. 8 . As shown in  FIG. 8 , polarizer  54  (i.e., an upper polarizer in this example) may have a polymer layer such as polarizer film (layer)  102 . Film  102  may be formed from a stretched polymer such as stretched polyvinyl alcohol (PVA) and may therefore sometimes be referred to as a PVA layer. A dichroic dye such as iodine  104  or dichroic organic pigments may be placed on the stretched PVA film to provide polarizer  54  with the ability to polarizer light. When layer  102  is coated with iodine  104 , iodine molecules align with the stretched film and form the polarizer. Other polarizer films may be used if desired. Polarizer film  102  may be sandwiched between other polymer layers. For example, the upper portion of layer  102  may be covered with one or more layers such as protective layer  106  and functional layer  108 . Layer  106  may be formed from a clear polymer. For example, layer  106  may be formed from a material such as tri-acetyl cellulose (TAC) and may sometimes be referred to as a TAC film. The TAC layer or other supporting substrate may help support and protect the PVA film. Functional layer  108  may include one or more layers of organic and/or inorganic material that serve as an antireflection coating, antismudge coating, or antiscratch coating, or may have layers that serve two or more such functions. Other films may be laminated to film  102  if desired. For example, lower film(s)  110  may be formed from one or more compensation films  110 A and  110 B (i.e., birefringent films such as cyclic olefin polymer films that help enhance off-axis viewing performance for display  14 ). Interposed adhesive layers may be used to hold some or all of the layers of material in polarizer  54  and other portions of display  14  together. 
     The presence of polarizer material over the entire surface of display  14  may create challenges in forming desired border regions and in mounting components behind display  14 . For example, it may be desirable to mount components such as a camera, ambient light sensor, light-based proximity sensor, or other light-based components  92  under unpolarized portion  96  of polarizer  54 . This allows the components to be hidden from view while using light that passes through the surface of display  14 . In the presence of polarizer material, light transmittance is generally cut in half. The reduced amount of light that would reach a camera, light sensor, or other light-based component in this type of arrangement would tend to decrease component performance (e.g., low-light camera and sensor performance would be degraded). This challenge can be addressed by forming an unpolarized area in polarizer  54  such as illustrative unpolarized area  96  of  FIG. 6B . The unpolarized area may be used in forming a light window such as a camera window or light sensor window in display  14  that is not subject to transmission losses due to polarizer material. The unpolarized area may also be used to cover text, graphics, or other content for which the light reduction associated with the polarized area of the polarizer is not desired. This content (e.g., text, graphics, etc.) may be formed using printed ink patterns (e.g., white, black, gray, colored, etc.), patterned metal, or other visible structures. 
     To eliminate the polarization properties of polarizer  54  and thereby form unpolarized region  96 , selected portions of polarizer  54  may be patterned by applying light, by applying chemicals, by physically removing polarizer material, by using masking techniques during polarizer formation, or using other polarizer patterning techniques. As shown in  FIG. 9 , for example, light source  112  may produce light  114 . When light  114  strikes the iodine or other dichroic dye on the surface of the polarizer, light  114  disrupts the dye sufficiently to prevent the dye from polarizing light. If desired, chemical treatment with chemical  116  ( FIG. 10 ) may be used after light bleaching polarizer  54  in this way. Chemical  116  may be, for example, an iodine cleaning agent such as sodium thiosulfate that prevents the disrupted iodine from reforming into its unbleached state (i.e., chemical  116  may chemically stabilize the bleached area). 
     If desired, chemical bleaching may be used to form unpolarized areas on polarizer  54 . As shown in  FIG. 11 , for example, dispenser  118  (e.g., a screen printing apparatus, a needle dispenser, an ink-jet printer, a gravure printing device, a pad printing device, a roller printing device, or other equipment) may be used to dispense bleaching agent  119  onto the surface of polarizer  54 . Bleaching agent  119  may be a chemical such as a strong base (e.g., KOH) that disrupts the polarization properties of the polarizer material on layer  54 , thereby forming unpolarized region  96 . After forming region  96  (by chemical treatment with chemical  119  and/or light bleaching using light  114  from light source  112 ), chemical stabilizer  116  (e.g., sodium thiosulfate, etc.) may optionally be applied over unpolarized region  96 . Polarizer  54  may then be stacked with layers  46 ′ above and/or below polarizer  54  to form display layers  46  for display  14 . 
     If desired, masking techniques can be used to create unpolarized area  96 , as illustrated in connection with  FIGS. 12, 13, 14, 15, and 16 . 
     Initially, polarizer layer  102  (e.g., a stretched PVA layer having a thickness of a few microns to 30 microns or other suitable thickness) may be mounted to a base layer such as base  120 , as shown in  FIG. 12 . Base layer  120  may be a polymer layer such as a TAC layer. 
     As shown in  FIG. 13 , patterned masking material  122  may be formed on the surface of PVA layer  102 . The masking material is deposited in areas that are to be free of polarizing material. The areas in which polarizing dye is to serve as a polarizing material for polarizer  54  are free from masking material  122 . 
     Masking material  122  may be a material such as a photoimageable polymer (e.g., photoresist that is patterned by application of ultraviolet light), may be a polymer that is deposited in a desired pattern using ink jet printing, screen printing, roll-based printing, etc., or may be other patterned mask material that is not readily dyed to create polarizing material upon exposure to dye  104 . After forming masking material  122 , dichroic dye  104  (e.g., iodine) may be used to cover the exposed upper surface of PVA layer  102 . Masking layer  122  may prevent dye  104  from reaching the upper surface of PVA layer  102  in selected area(s). Base layer  120  may prevent the dye from reaching the lower surface of PVA layer  102 . 
     This process results in a polarizer layer such as layer  102  that is selectively covered with polarizer  104  to produce polarized portions  100  (i.e., portions that contain polarizing material such as dye) and unpolarized portion  96  (i.e., portions that are free of polarizing material such as dye), as shown in  FIG. 14 .  FIG. 15  shows how an adhesive layer such as adhesive layer  124  may cover patterned layer  104  and mask  122  on the upper surface of layer  102 . Additional layers such as layers  126  and  128  may be attached to the upper surface of PVA layer  102  using adhesive  124 . Layer  126  may be a protective polymer such as a TAC layer. Layer  128  may be a functional coating such as an antireflection layer. Other layer(s) may be formed on top of layer  102  if desired (e.g., one or more layers with antireflection properties, antismudge properties, antiscratch properties, antireflection properties, and/or protection properties or other properties). Base film  120  can be removed, if desired, and replaced with layers such as layers  110  (e.g., one or more compensation layers such a layers  110 A and  110 B). A layer of adhesive on the lower surface of layer  102  and/or interposed adhesive layers between layers  110 A and  110 B may be used in attaching layers  110  to layer  102 . The inclusion of one or more additional layers on the top and/or bottom of layer  102  may serve to complete the formation of a polarizer layer such as upper polarizer  54 . 
       FIG. 16  shows how upper polarizer  54  and its unpolarized portion  96  may be mounted on display layers  46 ′ (e.g., a color filter layer, a thin-film transistor layer, etc.) to form display  14 . 
       FIGS. 17, 18, 19, 20, and 21  illustrate how masking material  122  may be removed as part of a mask-based process for forming a polarizer with a patterned unpolarized region. 
       FIG. 17  shows how PVA layer  102  may be attached to base layer  120 . 
       FIG. 18  shows how mask  122  may be patterned on the surface of PVA layer  102  and how dye  104  may be used to coat the uncovered portions of the upper surface of PVA layer  102 . 
     As shown in  FIG. 19 , the presence of masking structure  122  prevents dye  104  from forming polarizer  54  in region  96 . The presence of base layer  120  on the lower surface of PVA layer  102  may help prevent dye from dying the lower surface of layer  102 . 
     As shown in  FIG. 20 , masking structure  122  can be removed, leaving unpolarized region  96  on the surface of layer  104 . 
       FIG. 21  shows how base layer  120  may be removed, adhesive layer  124  may be used to attach addition layer(s) such as layer  126  (e.g., a TAC layer), optional additional layer  128  (e.g., a functional layer such as an antireflection layer, etc.) may be formed on layer  126 , and one or more additional layers  110  may be attached to the lower surface of PVA layer  102  (e.g., using layers of adhesive), thereby forming polarizer  54 . In this scenario, masking structure  122  was removed prior to the addition of layers such as layers  124 ,  126 ,  128 , and  110 , so polarizer  54  does not contain residual masking material. However, unpolarized region  96  remains in polarizer  54 , due to the absence of dye  104  within region  96 . 
     If desired, polarizer material may be removed from polarizer  54  to form unpolarized region  96 . This type of arrangement is illustrated in  FIG. 22 . As shown in  FIG. 22 , polarizer  54  may have layers such as PVA layer  102  coated with dye  104 , compensation layers  110 , and TAC layer  131 . Material removal tool  130  (e.g., a mechanical punch, a laser cutting tool, or other equipment for physically removing part of polarizer  54 ) may be used to form opening  132  in polarizer  54 . Polarizer  54  may be attached to display layers  46 ′ using adhesive  134 . Transparent polymer material  136  (e.g., ultraviolet light curable adhesive) may be used to fill opening  132 . Material  136  may have an index of refraction that is matched to the index of refraction of surrounding layers to help reduce reflections (i.e., material  136  may be index matched to layers  110 ,  102 , and  131 ). Additional layers such as adhesive layer  124 , TAC layer  126 , and functional layer  128  (e.g., an antireflection layer) may then be formed over the upper surface of PVA layer  126  and the exposed upper surface of material  136 . Due to the presence of material  136  in opening  132 , the surface of polarizer  54  will be smooth (i.e., there will not be a noticeable bump on the surface of polarizer  54  at the interface between region  96  and regions  110 ). 
       FIG. 23  is a flow chart of illustrative steps involved in using a dye bleaching arrangement to form unpolarized region  96 . 
     At step  138 , a dichroic dye such as iodine may be applied to a polarizer substrate such as a stretched PVA layer. 
     At step  140 , the stretched PVA layer coated with iodine may be treated with an acid such as boric acid to initiate cross-linking. 
     At step  142 , a strong base such as potassium hydroxide or other bleaching agent may be applied to a selected portion of the surface of the coated stretched PVA layer, bleaching the dye in the selected portion, and thereby forming unpolarized region  96 . A chemical stabilizer may optionally be applied to chemically stabilize the unpolarized region  96 . 
     At step  144 , coatings of adhesive may be applied to the upper and lower surfaces of the PVA layer. 
     Additional layers of polarizer  54  and additional display layers  46  may be attached to the PVA layer at step  146 . For example, a TAC layer and an antireflection coating or other functional layer may be attached to the upper surface of the PVA layer and compensation layers  110  or other layers may be attached to the opposing lower surface of the PVA layer. 
       FIG. 24  shows illustrative steps involved in forming a polarizer with unpolarized regions using masking techniques. 
     At step  150 , a patterned mask may be formed on a substrate such as stretched PVA layer  102 . The patterned mask may be a polymer. The polymer may be patterned using photolithographic techniques, using ink-jet printing, pad printing, screen printing, roll-based printing processes, or other patterning techniques. A base film may be attached to the lower surface of the PVA layer. 
     At step  152 , a dichroic dye such as iodine may be applied to PVA layer  102 . The base film on the lower surface of PVA layer  102  prevents the dye from coating the lower surface of layer  102 . The patterned mask on the upper surface of PVA layer  102  prevents the dye from coating the masked portion of the upper surface of PVA layer  102 , which therefore forms unpolarized region  96 . The remaining (unmasked) portions of PVA layer  102  are coated with the dye and become polarizing. 
     At step  154 , cross-linking may be promoted by applying an acid such as boric acid. 
     If desired, the mask may be removed at step  156 . 
     At step  158 , the base layer may be optionally removed and the opposing upper and lower surfaces of PVA layer  102  may be coated with adhesive. 
     Additional layers (e.g., a TAC layer and functional layer on the top and compensation layers on the bottom) may be attached to the PVA layer at step  160  to form polarizer  54  with unpolarized region  96 . 
     During masking operations, an ink jet printer may deposit liquid polymer masking material such as ultraviolet-light curable polymer or heat curable polymer at a resolution of less than 200 dots per inch, a resolution of more than 200 dots per inch, or other suitable resolution. One or more passes of the ink jet printer or other deposition equipment may be made to ensure adequate masking layer coverage. If desired, a waiting time (e.g., 1 second or more, 10 seconds or more, 100 seconds or more, or 1000 seconds or more) may be imposed between the initial deposition of the liquid polymer and the initiation of curing operations by application of ultraviolet light, an electron beam, and/or heat. The waiting time may help ensure that the individual dots of polymer that are deposited as part of the ink-jet deposition process have sufficient time to flow and merge with each other to form mask  122 . The masking material that is used in forming mask  122  may contain organic solvents and/or water. If desired, an ink that is free from solvent may be used as the masking material and PVA layer  102  may be maintained at a sufficiently high temperature to allow the deposited ink dots to spread and flow into each other to form mask  122 . 
     Unpolarized region  96  has different optical properties than polarized region  100  such as different transmission levels, different colors, different amounts of haziness, different polarizations (i.e., polarized and unpolarized), etc. Unpolarized region  96  may be aligned with transparent window structures to form light windows (i.e., unpolarized windows) in polarizer  54 . Unpolarized regions  06  may also overlap content such as text, graphics, icons, logos, and other content. In this type of scenario, the underlying structures that give rise to the content may be formed from colored dyes (e.g., red ink, blue ink, green ink, etc.), may be formed from metal, may be formed from black or white structures, etc. 
     When unpolarized region  96  is formed by light and/or chemical bleaching (with or without optional chemical stabilization), there may be a tendency of the residual material in the unpolarized region to reform into a polarizing material. This process can be accelerated in the process of moisture. To enhance the reliability of the polarizer (i.e., to ensure that the unpolarized region  96  will be maintained in its desired unpolarized state), one or more moisture barrier layers may be incorporated into display  14 . Moisture barrier layers may be formed from structures that exhibit low values of water vapor transmission rate (WVTR). For example, a moisture barrier layer may exhibit a WVTR value of less than 10 −2  g/m 2 -day, of less than 10 −3  g/m 2 -day, or other suitable value indicative of good moisture blocking. 
     Examples of materials that may be used in forming a moisture barrier layer include inorganic materials such as silicon oxide and aluminum oxide. A moisture barrier layer may be formed from multiple stacked inorganic layers such as these. Inorganic moisture barrier layers may be formed with a low density of microcracks that might otherwise allow moisture to penetrate an inorganic stack such as conventional antireflection coating (i.e., a conventional antireflection coating formed from alternating high and low index of refraction materials). 
     Moisture barrier layer may be formed from diamond-like coatings (e.g., a diamond-like coating coated on a substrate in a parallel plate reactor). A diamond-like coating may be formed from a material such as silicon oxide or aluminum oxide. If desired, diamond-like coatings may be deposited in the presence of carbon or nitrogen to tune the index of refraction of the diamond-like coating so that the diamond-like coating is index matched to nearby polymer layers. 
     If desired, moisture barriers may be formed from one or more layers of glass (e.g., a layer of glass having a thickness of 50 to 200 microns). 
     Moisture barrier films that are formed from moisture barrier coatings on polymer carriers and moisture barrier layers formed from a layer of glass may be attached to other display layers using adhesive. Moisture barrier films may also be deposited on display layers without using adhesive. For example, moisture barrier coatings can be deposited directly on a PVA layer or other display layers. 
     An illustrative polarizer of the type that may be provided with a moisture barrier layer to enhance reliability is shown in  FIG. 25 . Polarizer  54  has a polarizer film such as stretched PVA layer  102  coated with dichroic dye such as iodine  104 . Antireflection layer  128  (or other functional layer) may be supported by carrier layer  126  (e.g., a TAC layer or a layer of other clear polymer). Regions  100  of polarizer  54  in  FIG. 25  contain dye  104  and are polarizing. Region  96  is free of dye  104  and is therefore unpolarized. To prevent moisture from entering polarizer  54  and causing the residual material in region  96  from returning to a polarizing state, one or more moisture barrier layers such as moisture barrier layer  170  may be incorporated into polarizer  54 . As indicated by optional layers  172 , polarizer  54  may contain other layers of material (e.g., protective layers such as TAC layers, functional layers, etc.). Additional layer(s)  172  may be formed above or below PVA layer  102  and/or above or below moisture barrier layer  170 . The moisture blocking functionality of moisture barrier  170  may be particularly effective in scenarios in which the distance between moisture barrier layer  170  and PVA layer  102  (and dye layer  104 ) is minimized (i.e., scenarios in which moisture barrier layer  170  is adjacent to the upper surface of PVA layer  102  or is separated from moisture barrier layer  170  by only one, two, or other small number of intervening layers). Adhesive may be interposed between adjoining layers when layers are laminated together to form polarizer  54 . 
       FIG. 26  is an illustrative polarizer in which moisture barrier  170  has been attached to the upper surface of PVA layer  102 . Pressure sensitive adhesive layer  134  attaches TAC layer  126  to moisture barrier layer  170 . Moisture barrier layer  170  may include multiple inorganic layers  170 ′ such as silicon oxide layers, aluminum oxide layers, coatings such as diamond like coating formed from silicon oxide or aluminum oxide (e.g., silicon oxide or aluminum oxide grown in the presence of carbon, nitrogen, or other materials, etc.) or other suitable moisture barrier inorganic structures and may include an optional clear polymer carrier layer such as a layer of polyethyleneterephthalate (PET) having a thickness of about 10-50 microns. Moisture barrier layer  170  may, if desired, be formed from a relatively thick layer of glass (e.g., a glass layer of 50 to 200 microns in thickness). 
     A layer such as acrylic hard coat layer  174  may be formed on TAC layer  126  to provide scratch resistance. Additional function layers such as antireflection layer  128  may be formed on top of layer  174 . Layer  128  may have a 200 nm thickness or other suitable thickness. Layer  170  may have a thickness of 100 nm or other suitable thickness (e.g., less than 100 nm, more than 100 nm, 10-1000 nm, etc.). 
       FIG. 27  is a diagram of an illustrative configuration for polarizer  54  in which moisture barrier layer  170  has been formed between a pair of respective hard-coat covered TAC layers  180 . Layers  180  may each include a TAC substrate layer  184  covered with a respective acrylic hard coat layer  186 . In the illustrative configuration of  FIG. 28 , layers  180  are attached to each other using adhesive  134  and moisture barrier layer  170  is formed on top of the uppermost layer  180 , between the uppermost layer  180  and a functional layer such as antireflection coating  128 . If desired, one or both of hard coat layers  182  (e.g., the lower hard coat layer) may be omitted. Other configurations for incorporating moisture barrier layers into polarizer  54  may be used if desired. The illustrative configurations of  FIGS. 25, 26, 27, and 28  are presented as examples. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20131108
Publication Date: 20170411
Grant Date: 20170411
Priority Date: 20131108
Inventors: CHEN CHENG
KUWABARA MASATO
BOITNOTT CHRISTOPHER L.
QI JUN
GUPTA NATHAN K.
YIN VICTOR H.
ZHONG JOHN Z.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B5/3083", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/305", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F2001/133374", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2001/133538", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/305", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/3083", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133374", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133538", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B1/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/3083", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133533", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B1/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133374", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B1/11", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133538", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 53043544