PATENT DOCUMENT

Publication Number: US-9638950-B2
Application Number: US-201414278768-A
Country: US
Kind Code: B2

Title: Display with opaque border resistant to electrostatic discharge

Abstract:
A display may have a color filter layer and a thin-film transistor layer. A liquid crystal layer may be located between the color filter layer and the thin-film transistor layer. The display may have an active area surrounded by an inactive area. The opaque border layer may contain first and second opaque layers in the inactive area. The first opaque layer may have an opening in the inactive area that is overlapped by an isolation layer. The second opaque layer may be located in the inactive area and may overlap the opening in the first opaque layer to block light in the inactive area. The isolation layer may be interposed between the first and second opaque layers and may prevent static charge from an electrostatic discharge event along the edge of the display from migrating to the active area through the opaque border in the inactive area.

Claims:
What is claimed is: 
     
       1. A display having an active area surrounded by an inactive area, comprising:
 a color filter layer having an inner surface and an opposing outer surface, wherein the color filter layer includes an opaque border on its inner surface in the inactive area, wherein the opaque border includes a first opaque layer, a second opaque layer, and an isolation layer interposed between at least some of the first opaque layer and some of the second opaque layer that prevents electrostatic charge from migrating to the active area through the inactive area; 
 a thin-film transistor layer; and 
 a layer of liquid crystal material between the color filter layer and the thin-film transistor layer, wherein the first and second opaque layers are interposed between the layer of liquid crystal material and the inner surface, and wherein the first opaque layer is interposed between the second opaque layer and the inner surface. 
 
     
     
       2. The display defined in  claim 1  wherein the color filter layer and the thin-film transistor layer form an array of pixels in the active area of the display. 
     
     
       3. The display defined in  claim 2  wherein the isolation layer comprises an inorganic layer. 
     
     
       4. The display defined in  claim 3  wherein the isolation layer is formed in the inactive area and does not overlap the active area. 
     
     
       5. The display defined in  claim 3  wherein the inorganic layer comprises a transparent material. 
     
     
       6. The display defined in  claim 5  wherein the transparent material comprises a material selected from the group consisting of: an oxide and a nitride. 
     
     
       7. The display defined in  claim 5  wherein the first and second opaque layers comprise polymer. 
     
     
       8. The display defined in  claim 7  wherein the polymer comprises black polymer. 
     
     
       9. The display defined in  claim 8  wherein the second opaque layer does not overlap the active area and wherein the color filter layer comprises:
 a black matrix formed from a portion of the first opaque layer; and 
 color filter elements in openings in the black matrix. 
 
     
     
       10. The display defined in  claim 9  wherein the color filter layer comprises a clear glass substrate, wherein the first and second opaque layers and the isolation layer are formed on the clear glass substrate, wherein the color filter layer further comprises a planarizing layer formed from clear polymer, wherein the planarizing layer is interposed between the clear glass substrate and the liquid crystal layer, and wherein the planarizing layer overlaps the first and second opaque layers, the isolation layer, and the color filter elements. 
     
     
       11. The display defined in  claim 1  wherein the first opaque layer has an opening that runs along four peripheral edges of the color filter layer. 
     
     
       12. The display defined in  claim 11  wherein the second opaque layer overlaps the opening. 
     
     
       13. The display defined in  claim 12  wherein the isolation layer comprises a transparent inorganic material. 
     
     
       14. The display defined in  claim 13  wherein the transparent inorganic material overlaps the opening. 
     
     
       15. The display defined in  claim 14  wherein portions of the first opaque layer are located on opposing sides of the opening. 
     
     
       16. A display having an active area surrounded by an inactive area, comprising:
 a color filter layer having an inner surface and an opposing outer surface, wherein the color filter layer includes an opaque layer on its inner surface, wherein a first portion of the opaque layer forms an opaque border in the inactive area, wherein a second portion of the opaque layer forms a black matrix in the active area, wherein the color filter layer has color filter elements in openings in the black matrix, wherein a peripheral isolation gap separates the first portion from the second portion and prevents electrostatic charge from migrating to the active area through the inactive area, wherein the color filter layer includes an isolation layer having a portion formed in the peripheral isolation gap, and wherein the color filter layer includes an additional opaque layer on its inner surface that overlaps the portion of the isolation layer formed in the peripheral isolation gap; 
 a thin-film transistor layer; and 
 a layer of liquid crystal material between the color filter layer and the thin-film transistor layer. 
 
     
     
       17. The display defined in  claim 16  further comprising a planarizing polymer overcoat layer that covers the first and second portions of the opaque layer.

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 and portable computers may have displays for presenting information to a user. 
     Liquid crystal displays contain a layer of liquid crystal material. Display pixels in a liquid crystal display contain thin-film transistors and electrodes for applying electric fields to the liquid crystal material. The strength of the electric field in a display pixel controls the polarization state of the liquid crystal material and thereby adjusts the brightness of the display pixel. 
     Substrate layers such as color filter layers and thin-film transistor layers are used in liquid crystal displays. A thin-film transistor layer contains an array of the thin-film transistors that are used in controlling electric fields in the liquid crystal layer. A color filter layer contains an array of color filter elements such as red, blue, and green elements. The color filter layer provides the display with the ability to display color images. 
     In an assembled display, the layer of liquid crystal material is sandwiched between the thin-film transistor layer and the color filter layer. The center of the display forms an active area that is occupied by an array of pixels. The border of the display is inactive and may contain support circuitry. In the inactive border, opaque masking material is used to prevent stray light from escaping from the display and to hide support circuitry from view by a user of the display. 
     The opaque masking material is formed from an opaque material such black ink. The black ink is formed from a photoimageable polymer that contains a black filler material. The black ink is an insulator, but is generally not able to withstand high voltages. During electrostatic discharge events in which a user touches the edge of the display, high voltages such as voltages on the order of 10 kV or higher may be applied to the black ink. The black ink cannot reliably withstand these high voltages, so static charge may migrate into the active area of the display through the black ink. This disrupts the electric field distribution within the liquid crystal material of the display and leads to visible artifacts. As an example, the pixels of the display near the border may exhibit a visible color cast, because pixels of different colors respond differently to the disruption from the static charge. 
     In an effort to enhance immunity to electrostatic discharge, some displays have opaque masking layers that are recessed from the outermost edge of the display. This creates a high resistance air gap that can resists electrostatic discharge, but involves the addition of an overlapping opaque gasket structure on the outside of the layers in the display to prevent light leakage. The overlapping opaque gasket structure may undesirably increase the bulk of the display structures at the edge of the display. 
     It would therefore be desirable to be able to provide improved electronic device displays with structures that prevent display damage from electrostatic discharge. 
     SUMMARY 
     A display may have a color filter layer and a thin-film transistor layer. A layer of liquid crystal material may be located between the color filter layer and the thin-film transistor layer. The display may have an active area surrounded by an inactive area. 
     The thin-film transistor layer may have an array of pixel electrodes and pixel circuits in the active area. The color filter layer may have a black matrix in the active area. The black matrix may have openings that receive color filter elements. 
     An opaque border layer may be formed in the inactive area. The opaque border layer may contain first and second opaque layers. The first opaque layer may have portions in the inactive area that form the black matrix. In the inactive area, the first opaque layer may have an opening that is overlapped at least partly by an isolation layer. The second opaque layer may be located in the inactive area and may overlap the opening in the first opaque layer to block light in the inactive area. The isolation layer may be interposed between the first and second opaque layers and may prevent static charge from an electrostatic discharge event along the edge of the display from migrating to the active area through the opaque border in the inactive area. The isolation layer may be formed form an inorganic material such as silicon nitride or other transparent inorganic layer or may be formed from a polymer such as clear polymer that is also used to form a planarizing overcoat layer in the active area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a laptop computer with a display in accordance with an embodiment. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a handheld electronic device with a display in accordance with an embodiment. 
         FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer with a display in accordance with an embodiment. 
         FIG. 4  is a perspective view of an illustrative electronic device such as a computer display 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. 6  is a top view of an array of pixels in a display in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of a portion of a display showing how the display may have a border with light-blocking structures in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of a portion of an illustrative electronic device showing how the edge of the display may be exposed to electrostatic discharge in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of a portion of a display layer such as a color filter layer that has been provided with an electrostatic-discharge-resistant opaque border by filling an opening in a first opaque layer with an isolation layer and covering the isolation layer and the opening with a second opaque layer in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of a portion of a display layer such as a color filter layer that has been provided with an electrostatic-discharge-resistant opaque border by interposing an isolation layer between overlapping opaque masking layers along the periphery of the display layer in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of a portion of a display layer such as a color filter layer that has been provided with an electrostatic-discharge-resistant opaque border by interposing a peripheral ring of isolation layer material that is inset from the edge of the display layer between overlapping opaque masking layers in accordance with an embodiment. 
         FIG. 12  is a cross-sectional side view of a portion of a display layer such as a color filter layer that has been provided with an electrostatic-discharge-resistant opaque border by interposing an isolation layer formed from a portion of a planarizing overcoat layer between respective opaque masking layers in accordance with an embodiment. 
         FIG. 13  is a top view of a corner portion of an illustrative color filter layer in which a black matrix region has been separated from a black border by a gap in accordance with an embodiment. 
         FIGS. 14 and 15  are cross-sectional side views of portions of the color filter layer of  FIG. 13  in accordance with an embodiment. 
         FIG. 16  is a top view of a corner portion of an illustrative color filter layer in which a peripheral gap filled with overcoat polymer has been formed within a black border in accordance with an embodiment. 
         FIG. 17  is a cross-sectional side view of a portion of the color filter layer of  FIG. 16  in accordance with an embodiment. 
         FIG. 18  is a top view of a corner portion of an illustrative color filter layer in which a peripheral gap filled with blue color filter layer material has been formed within a black border in accordance with an embodiment. 
         FIG. 19  is a cross-sectional side view of a portion of the color filter layer of  FIG. 18  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may include displays. The displays may be used to display images to a user. Illustrative electronic devices that may be provided with displays are shown in  FIGS. 1, 2, 3, and 4 . 
     Illustrative electronic device  10  of  FIG. 1  has the shape of a laptop computer having upper housing  12 A and lower housing  12 B with components such as keyboard  16  and touchpad  18 . Device  10  may have hinge structures  20  that allow upper housing  12 A to rotate in directions  22  about rotational axis  24  relative to lower housing  12 B. Display  14  may be mounted in upper housing  12 A. Upper housing  12 A, which may sometimes be referred to as a display housing or lid, may be placed in a closed position by rotating upper housing  12 A towards lower housing  12 B about rotational axis  24 . 
       FIG. 2  shows how electronic device  10  may be 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  may have opposing front and rear surfaces. Display  14  may be mounted on a front face of housing  12 . Display  14  may, if desired, have openings for components such as button  26 . Openings may also be formed in display  14  to accommodate a speaker port (see, e.g., speaker port  28  of  FIG. 2 ). 
       FIG. 3  shows how electronic device  10  may be a tablet computer. In electronic device  10  of  FIG. 3 , housing  12  may have opposing planar front and rear surfaces. Display  14  may be mounted on the front surface of housing  12 . As shown in  FIG. 3 , display  14  may have an opening to accommodate button  26  (as an example). 
       FIG. 4  shows how electronic device  10  may be a computer display or a computer that has been integrated into a computer display. With this type of arrangement, housing  12  for device  10  may be mounted on a support structure such as stand  30  or stand  30  may be omitted (e.g., stand  30  can be omitted when mounting device  10  on a wall). Display  14  may be mounted on a front face of housing  12 . 
     The illustrative configurations for device  10  that are shown in  FIGS. 1, 2, 3, and 4  are merely illustrative. In general, electronic device  10  may be a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     Housing  12  of device  10 , which is sometimes referred to as a case, may be formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials. Device  10  may be formed using a unibody construction in which most or all of housing  12  is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures). 
     Display  14  may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. Touch sensors for display  14  may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components. 
     Display  14  for device  10  includes display pixels formed from liquid crystal display (LCD) components or other suitable image pixel structures. 
     A display cover layer may cover the surface of display  14  or a display layer such as a color filter layer or other portion of a display may be used as the outermost (or nearly outermost) layer in display  14 . The outermost display layer may be formed from a transparent glass sheet, a clear plastic layer, or other transparent member. 
     A cross-sectional side view of an illustrative configuration for display  14  of device  10  (e.g., for display  14  of 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 form a liquid crystal display or may be used in forming displays of other types. 
     In a configuration in which display layers  46  are used in forming a liquid crystal display, 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 polarizer layer  60  and upper 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, lower layer  58  may be a color filter layer and upper layer  56  may be a thin-film transistor layer. Another illustrative configuration involves forming color filter elements and thin-film transistor circuits with associated pixel electrodes on a common substrate. This common substrate may be the upper substrate or may be the lower substrate and may be used in conjunction with an opposing glass or plastic layer (e.g., a layer with or without any color filter elements, thin-film transistors, etc.) to contain liquid crystal layer  52 . Illustrative configurations for display  14  in which layer  56  is a color filter layer and layer  58  is a thin-film transistor layer are sometimes described herein as an example. 
     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 A or  62 B 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. If desired, light sources such as light source  72  may be located along multiple edges of light guide plate  78 . 
     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. If desired, optical films such as these may be incorporated into other portions of display  14 . For example, compensation films may be incorporated into polarizer layers, etc. 
     As shown in  FIG. 6 , display  14  may include an active area such as rectangular active area AA that displays images for a user and may include an inactive area such as inactive border area IA that runs along one or more edges of active area AA. As an example, inactive border area IA may form a rectangular ring that surrounds active area AA, as shown in  FIG. 6 . 
     Active area AA contains pixel array  92 . Pixel array  92  contains an array of pixels such as pixels  94 . Pixel array  92  may be controlled using control signals produced by display driver circuitry. The display driver circuitry may include one or more integrated circuits (e.g., timing controller integrated circuits) and/or thin-film transistor circuitry (e.g., data line demultiplexing circuitry and/or gate driver circuitry on layer  58 ). The display driver circuitry of display  14  (e.g., the thin-film transistor circuitry such as the demultiplexer circuitry and gate driver circuitry) may be located in inactive area IA. As an example, gate driver circuits may run along the left and right edges of display  14  in inactive area IA. 
     During operation of device  10 , control circuitry in device  10  such as memory circuits, microprocessors, and other storage and processing circuitry may provide data to the display driver circuitry. The display driver circuitry may convert the data into signals for controlling rows and columns of display pixels  94  in pixel array  92 . 
     Pixels  94  in pixel array  92  may contain thin-film transistor circuitry (e.g., polysilicon transistor circuitry or amorphous silicon transistor circuitry) and associated electrode structures for producing electric fields across liquid crystal layer  52  in display  14 . Each display pixel may have a respective thin-film transistor to control the application of electric fields to a respective pixel-sized portion of liquid crystal layer  52 . 
     The thin-film transistor structures that are used in forming pixels  94  may be located on a thin-film transistor substrate such as a layer of glass. The thin-film transistor substrate and the structures of display pixels  94  that are formed on the surface of the thin-film transistor substrate collectively form thin-film transistor layer  58  of  FIG. 5 . 
     A cross-sectional side view of display  14  of  FIG. 6  taken along line  96  and viewed in direction  98  is shown in  FIG. 7 . As shown in  FIG. 7 , liquid crystal layer  52  may be interposed between color filter layer  56  and thin-film transistor layer  58 . Thin-film transistor layer  58  may include a substrate such as substrate  100 . Substrate  100  may be formed from a layer of glass, a plastic layer, or other substrate material. Thin-film transistor circuitry may be formed on substrate  100 . For example, thin-film transistor layer  58  may have thin-film transistor circuitry  104  in active area AA. Thin-film transistor circuitry  104  includes electrodes for applying electric fields to liquid crystal layer  52  and includes thin-film transistors for controlling the application of the electric fields to crystal layer  52 . In inactive area IA along the periphery of display  14 , thin-film transistor layer  58  may have display driver circuitry such as thin-film transistor driver circuitry  102 . Driver circuitry  102  may include gate drivers, demultiplexer circuitry, and other circuitry for controlling the pixel circuits of thin-film transistor circuitry  104  in active area AA. 
     A ring of adhesive such as adhesive  106  may run along each of the four peripheral edges of display  14  and may provide lateral confinement for liquid crystal layer  52 . Adhesive  106  may be formed from epoxy or other adhesive materials. Adhesive ring  106  may be formed within inactive area IA and may attach the upper surface of thin-film transistor layer  58  to the opposing lower surface of color filter layer  56 . 
     Color filter layer  56  may have a substrate such as substrate  108 . Substrate  108  may be formed from a clear glass layer, a transparent plastic layer, or a layer of other transparent substrate material. The lower surface of color filter layer  56  may contain patterned opaque masking material such as patterned black ink, white ink, or ink or materials of other colors. Configurations in which the opaque masking material is based on an opaque material such as black ink are sometimes described herein as an example. This is, however, merely illustrative. Opaque masking material for display  14  may be formed from any suitable opaque material or materials (e.g., organic materials such as polymers, inorganic materials such as oxides or nitrides, metals, combinations of these materials, etc.). 
     In inactive area IA, opaque masking material is used in forming opaque border  110 . Opaque border  110  may run along each of the four peripheral edges of a rectangular display (as an example). In active area AA, the opaque masking material is patterned to form patterned opaque masking material matrix  112  (sometimes referred to as an opaque matrix or black matrix). Black matrix  112  may form a grid-like pattern with openings for respective color filter elements  114 . Color filter elements  114  and, if desired, material for opaque masking material matrix  112  and opaque masking material border  110  may be formed from photoimageable polymer. For example, red, green, and blue photoimageable polymers may be used for forming red, green, and blue color filter elements  114  for a color filter array on the lower surface of color filter layer  56  and photoimageable black polymer may be used in forming black matrix  112  and border  110 . Each color filter element  114  may be located in a respective opening in opaque matrix  112  and may be aligned with a respective pixel electrode in the array of electrodes formed in thin-film transistor circuitry  104  of thin-film transistor layer  58 . Black photoimageable polymer (e.g., a polymer into which a black filler material such as carbon black or other opaque material) or other opaque materials may be used in forming opaque border  110 . 
     A cross-sectional side view of an edge portion of display  14  mounted in an illustrative housing for device  10  is shown in  FIG. 8 . As shown in  FIG. 8 , an L-shaped gasket such as gasket  122  or a gasket or mounting structure of other suitable shapes may be used in mounting display  14  within housing  12 . Gasket  122  may be formed from an elastomeric material that helps prevent damage to outer vertical edge  126  of display  14 . In configurations of the type shown in  FIG. 8 , there may be an air gap such as gap  118  between inner surface  124  of gasket  122  and outermost edge surface  126  of display  14  (i.e., the outermost edge surfaces of color filter layer  56  and thin-film transistor layer  58 ). Gap  118  may have a width of about 200 microns, less than 300 microns, more than 100 microns, or other suitable size. The outer surface of color filter layer  56  may be coated with a transparent conductive electrostatic discharge protection layer such as layer  160 . Layer  160  may be formed form a transparent conductive material such as indium tin oxide and may be used in dissipating electrostatic charge from the surface of display  14 . 
     In the presence of human body parts such as finger  116  or other external objects, there is a potential for static charge to be deposited on layers of display  14  such as opaque border  110  and adhesive  106  during an electrostatic discharge event. Charge can reach edge  126  of display  14  from an adjacent external object such as finger  116  and/or can migrate to edge  126  from other portions of the display such as the active area of the display via electrostatic discharge protection layer  160 . If care is not taken, electrostatic charge that is deposited onto edge  126  of display  14  during an electrostatic discharge event can migrate inwardly through border  110  as shown by path  120 . Opaque materials such as polymers with opaque filler material (e.g., fillers such as carbon black, etc.) may not be able to withstand the extremely high voltages (e.g., 10 kV or more) that can be produced during an electrostatic discharge event, so the presence of materials such as black photoimageable polymer in border layer  110  can create potential pathways that potentially could allow the static charge to reach the outer edges of active area AA (i.e., the liquid crystal material of layer  52  and thin-film transistor circuitry  104 ). This could visibly disrupt the proper operation of display  14  at the edges of active area AA. 
     To enhance immunity to disruption from static charge during electrostatic discharge events, opaque border  110  of display  14  may be provided with an isolation layer that serves to form an isolating border around display  14 . The isolation layer may, as an example, be formed from one or more electrically isolating materials such as inorganic materials. The inorganic material layers may include materials such as silicon oxide, metal oxide (e.g., aluminum oxide), silicon nitride, oxynitrides, or other inorganic dielectric materials that are capable of withstanding elevated voltages (e.g., 10 kV or greater) of the type that are experienced during electrostatic discharge events. The inorganic dielectric layers may be deposited using plasma-enhanced chemical vapor deposition, other types of chemical vapor deposition, physical vapor deposition, or other suitable deposition techniques. If desired, the isolation layer may be formed from a polymer or other organic dielectric that is capable of withstanding elevated voltages (e.g., 10 kV or greater) of the type that are experienced during electrostatic discharge events. 
     To enhance the ability of the isolation layer to withstand high voltages, the isolation layer may be formed from a material that is free of opaque fillers (e.g., the isolation layer may be a layer that is free of carbon black or other black materials). As a result, the isolation layer may be transparent or may have a non-black color. To ensure that opaque border layer  110  successfully blocks light around the border of display  14  (e.g., to prevent backlight from backlight unit  42  from leaking out of display  14  along the edge of display  14  and/or to block a user&#39;s view of inactive area structures such as thin-film transistor circuitry  102 ), it may be desirable to ensure that one or more opaque layers of material in border  110  overlap any regions in which transparent inorganic material has been deposited. 
     An illustrative configuration for an opaque border that is resistant to electrostatic discharge is shown in  FIG. 9 . In the example of  FIG. 9 , two opaque masking layers have been used for display  14 : opaque masking layer  130  and opaque masking layer  132 . Layers  130  and  132  may be formed from opaque material such as opaque photoimageable polymer (e.g., black photoimageable polymer). Other opaque materials may be used for forming layers  130  and  132  if desired. 
     In the  FIG. 9  arrangement, layer  130  is deposited and patterned on lower (inner) surface  138  of color filter layer substrate  108 . In active area AA, layer  130  is patterned to form opaque matrix  112  and has openings that are filled with color filter elements  114 . In inactive area IA, layer  130  is patterned to form part of opaque border layer  110 . As shown in  FIG. 9 , layer  130  in inactive area IA may be formed on lower surface  138  of color filter layer substrate  56  and may be patterned to have an opening such as opening  136 . With one suitable arrangement, border  110  and opaque layer  130  in inactive area IA may from a rectangular ring-shaped border that surrounds all four peripheral sides of display  14 . In this type of arrangement, opening  136  may form a concentric rectangular ring that also runs along each of the four peripheral edges of display  14 . 
     Opening  136  may be filled with an isolation layer. The isolation layer may be formed from a material such as material  134  that has an enhanced ability to withstand electrostatic discharge events relative to materials such as opaque photoimageable polymer materials in inactive area IA. Material  134  may be, for example, formed from an inorganic material such as silicon nitride, silicon oxide, a metal oxide, oxynitride material, or other inorganic material that can serve as a charge isolation layer. Material  134  may form a rectangular ring that runs around the four peripheral sides of display  14 . To ensure that border  110  is opaque across its entire width, second opaque masking layer  132  may be deposited over layer  134  and opening  136 . Opaque masking layer  132  may have the shape of a rectangular ring that overlaps the rectangular ring shape of opening  136  and ensures that light is completely blocked by layer  130  and/or layer  132  within inactive area IA. Layer  132  need not be formed in active area AA (i.e., active area AA may be free of layer  132 ). 
     Materials  130  and  132  may be formed form black ink or other opaque material such as an opaque photoimageable polymer. Material  134  may be formed from a transparent inorganic material such as silicon nitride that is deposited using plasma-enhanced chemical vapor deposition. Material  134  has a higher resistivity (e.g., 10 15 -10 16  ohm-cm) than materials  130  and  132  and has a greater ability to block static charge during an electrostatic discharge event. The presence of the isolation layer formed form material  134  within opaque border layer  110  (i.e., interposed between parts of layers  130  and  132 ) therefore helps enhance the ability of border layer  110  to prevent disruption to the operation of the edges of active area AA of display  14  from electrostatic discharge. As a result, display  14  may be mounted in housing  12  using a relatively unprotected mounting configuration of the type shown in  FIG. 8  (i.e., a structure using an L-shaped gasket such as gasket  122  or other gasket that does not overlap the front surface of color filter layer  56  and which therefore tends to expose edge  126  of display  14  to external objects such as user&#39;s finger  116 ). 
     To ensure that opaque border  110  blocks light completely, width W 3  of opaque layer  132  may be larger than width W 1  of opening  136 . To prevent layers  130  and  132  from contacting each other in a way that forms a low-resistance path from the edge of display  14  to active area AA), width W 2  of isolation layer  134  may be larger than width W 3  of opaque masking layer  132  or other configurations can be used to electrically isolate at least parts of layers  130  and  132  from each other with interposed isolation layer material. As an example, width W 2  may be large enough relative to width W 3  to create a lateral gap W 4  of about 200 microns (100-300 microns, more than 100 microns, less than 300 microns, etc.) between layer  130  and layer  132  (e.g., along the outer edge of layer  142 ). The value of W 4  may be configured to be sufficiently large to prevent electrostatic charge from bridging gap W 4  during an electrostatic discharge event. 
     With the illustrative configuration of  FIG. 9 , outermost edge  140  of layer  132  may be pulled back from edge  126  of color filter substrate  108  in color filter layer  56  (e.g., by width W 4  or greater) Innermost edge  142  of layer  132  may be laterally separated from layer  130  by a width W 5  or layer  130  may be extended inwardly to overlap layer  130 , as shown by dotted line  144 . In configurations for opaque border  110  in which layers  132  and  130  are not electrically isolated, edge  140  is preferably pulled back from edge  126  and outermost edge  146  of isolation layer  134  by a sufficient amount to prevent layers  130  and  132  from forming a path that allows charge to reach layer  132 . 
     The underside of color filter layer  56  (e.g., layers  130 ,  134 , and  132 , color filter elements  114 ) may be coated with a planarization layer such as overcoat layer  148 . Overcoat layer  148  may be formed form an organic layer such as a clear polymer layer. 
     Another illustrative configuration for opaque border  110  is shown in  FIG. 10 . In the example of  FIG. 10 , opening  136  in opaque masking layer  130  in inactive area IA extends to edge  126  of color filter layer substrate  108 . Isolation layer  134  may be wider than width W 6  of opening  136 , so that isolation layer  134  completely overlaps opening  136  (as an example). The width of opaque layer  132  is preferably wider than width W 6  to ensure that light is blocked everywhere within inactive area IA. Width W 6  of isolation layer  134  in opening  136  and width W 7  separating layer  132  from layer  130  may be sufficiently large (e.g., 200 microns, 100-300 microns, more than 100 microns, less than 300 microns, etc.) to prevent charge from penetrating from edge  126  to the structures at the edge of active area AA through layers  132  and/or  130 . Overcoat layer  148  may serve as a planarization layer that covers the inner surface of color filter layer  56 . 
     With the illustrative configuration of  FIG. 11 , opaque border  110  has first opaque layer  130  and second opaque layer  132  (e.g., black ink layers). Opaque layer  130  may have portions in active area AA that are used in forming opaque matrix  112  in active area AA. In inactive area IA, opaque layer  130  may be used to form an opaque structure that overlaps opening  150  in layer  132 , thereby blocking light in area IA. Inorganic isolation layer  134  may isolate layers  130  and  132  from each other. Isolation layer  134  may also isolate outer portion  132 - 1  of layer  132  from inner portion  132 - 2  of layer  132 . This isolates outer (edge) portion  132 - 1  of layer  132  from portion  130 ′ of layer  130  near the edge of active area AA. The isolation provided by isolation layer  134  therefore prevents electrostatic discharge from reaching active area AA through a path formed from layers  130  and  132  and prevents disruption to the operation of display  14 . The width of opening  150 , the width of the gap between layer  132 - 1  and layer  130  under opening  150 , and the width of the gap between layer  130  and layer  132 - 2  are preferably sufficiently large (e.g., 200 microns, 100-300 microns, more than 100 microns, less than 300 microns, etc.) to prevent electrostatic charge from reaching portion  130 ′ of layer  130  and active area AA from the outer edge of layer  56 . 
       FIG. 12  shows an arrangement in which overcoat layer  148  (e.g., a clear polymer layer) serves as an isolation layer between first opaque layer  130  and second opaque layer  132 . The thickness and resistivity of layer  148  are sufficient to prevent electrostatic charge that is deposited onto layer  132  at edge  126  of layer  56  from reaching layer  130  in active area AA through a path formed form layer  130  and/or layer  132 . Opening  136  in layer  130  may be formed along outer edge  126  of color filter layer  56  as shown in  FIG. 12  or may be inset from edge  126 . Layers  130  and  132  overlap within inactive area IA. In the arrangement of  FIG. 12 , for example, layers  132  and  132  may overlap along the inner edge of opening  136 . 
     As with the illustrative configurations of  FIGS. 9, 10, and 11 , the arrangement of  FIG. 12  ensures that all of inactive area IA is overlapped by either opaque layer  130  or opaque layer  132  or both layers  130  and  132 . At the same time, isolation material (i.e., material  134  in the configurations of  FIGS. 9, 10, and 11  or a portion of layer  148  in the configuration of  FIG. 12 ) that has a higher resistivity and a greater ability to withstand high voltages during electrostatic discharge events is interposed between layers  130  and  132  where they overlap to ensure that charge does not flow from the outer edge of the display to active area AA along a path formed form layer  130  and/or layer  132 . 
       FIG. 13  is a top view of an illustrative configuration for color filter layer  56  in which opening  136  has a rectangular ring shape and is formed along the inner edge of opaque border layer  130 . Color filter elements  114  may be rectangular or may have chevron shapes as shown in  FIG. 13 . Gap  136  may be filled with isolating material such as overcoat layer  148  and/or portions of the color filter element material used in forming blue, red, and green color filter elements  114 . Blue (and red) color filter materials (e.g., blue photoimageable polymer and red photoimageable polymer) may have a higher resistivity than green color filter materials (e.g., green photoimageable polymer), so it may be desirable to form the outermost color filter elements  114  from blue (and red) color filter elements to reduce visible disruptions due to the presence of static charge during an electrostatic discharge event. 
       FIG. 14  is a cross-sectional side view of color filter  56  of  FIG. 13  taken along line  162  of  FIG. 13  and viewed in direction  164 . As shown in  FIG. 14 , some of overcoat layer  148  may penetrate into opening  136  between opaque border layer  130  in inactive area IA and the portion of layer  130  that forms black matrix  112  in active area IA. This overcoat layer material may have a higher resistivity than the material used to form layer  130  and the portion of this layer that forms black matrix  112 , so the overcoat material in opening  136  may serve as an isolation layer for the border of display  14 . 
       FIG. 15  is a cross-sectional side view of color filter  56  of  FIG. 13  taken along line  166  and viewed in direction  168 . In this portion of color filter  56 , blue color filter element material  114  may penetrate into opening  136  and may form part of the isolation layer. 
       FIG. 16  is a top view of another illustrative arrangement for color filter  56 . In the  FIG. 16  example, opening  136  is a rectangular ring-shaped opening that lies within opaque layer  130  of inactive area IA.  FIG. 17  is a cross-sectional side view of the color filter layer of  FIG. 16  taken along line  170  and viewed in direction  172 . A portion of opaque layer  130  in inactive area IA lies within the boundary formed by opening  136 , as shown in  FIG. 17 . Some of overcoat layer  148  may penetrate into opening  136  and may form an isolation layer for the border of display  14  (i.e., gap  136  forms a peripheral isolating gap filled with planarizing overcoat material  148 ). Blue color filter elements  114  and red color filter elements  114  may be located along the outermost edge of the active area, because green color filter elements  114  are less resistive and more sensitive to electrostatic charge. 
     In the illustrative configuration of  FIG. 18 , ring-shaped opening  136  in opaque layer  130  of inactive area IA has been filled with blue color filter element material (e.g., blue photoimageable polymer). In this situation, the blue color filter element material in opening  136  serves as isolation material that helps form an isolating border for display  14  (i.e., gap  136  forms a peripheral isolating gap filled with blue photoimageable polymer).  FIG. 19  is a cross-sectional side view of color filter layer  56  of  FIG. 18  taken along line  174  and viewed in direction  176 . As shown in  FIG. 19 , blue (B) color filter element material may be formed in opening  136  and therefore serves as isolation layer  134 . The blue material of layer  134  may be deposited on color filter layer substrate  108  at the same time that blue (B) color filter elements  114  are being deposited and patterned within the openings of black matrix  112 . 
     Openings such as illustrative openings  136  of  FIGS. 13-19  may have any suitable width (e.g., 5-20 microns, about 10 microns, more than 5 microns, less than 20 microns, etc.). When opening  136  is narrow (e.g., 5-20 microns), the presence of opening  136  in the opaque border of display  14  may be invisible to the naked eye or at least unnoticeable to most users of device  10 . 
     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: 20140515
Publication Date: 20170502
Grant Date: 20170502
Priority Date: 20140515
Inventors: YANG YOUNG CHEOL
ZHU XINYU
YAN JIN
CHEN CHENG
CHIU PO-WEN
QI JUN
YIN VICTOR H.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/133514", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2001/133357", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133512", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/1368", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2001/133388", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/136204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2202/22", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133357", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1368", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133512", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F2202/22", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133512", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/136204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133514", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133388", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133388", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 54538393