Patent Application
20170005116
This relates generally to electronic devices, and, more particularly, to electronic devices with displays.
Electronic devices such as cellular telephones, computers, and other electronic equipment often contain displays for presenting images to a user. Liquid crystal displays and other displays have backlight units that provide backlight for the display. The backlight unit generates light that travels outwards through the pixels of the display. Use of a backlight unit allows a display to display images in a variety of ambient lighting conditions.
Displays such as liquid crystal displays may contain layers of transparent substrate material such as layers of glass. Glass substrate layers may be used in forming display layers such as color filter layers and thin-film transistor layers. The color filter layer in a liquid crystal display may have an array of color filter elements for providing the display with the ability to display color images. The thin-film transistor layer may have thin-film transistor display driver circuitry and an array of pixel circuits that apply signals to pixel electrodes. A layer of liquid crystal material may be interposed between the color filter layer and the thin-film transistor layer. The color filter layer, liquid crystal layer, and thin-film transistor layer may be interposed between upper and lower polarizer layers. During operation of the display, pixel electrodes supply electric fields to corresponding pixel-sized portions of the liquid crystal layer, thereby adjusting the amount of light transmitted through each of the pixels of the display.
The thin-film transistor layer in a liquid crystal display typically extends past the edge of the color filter layer and other layers in the display and thereby forms a thin-film transistor ledge. Because the ledge is less supported than other portions of the display, the ledge may be vulnerable to damage during a drop event. Some support for the thin-film transistor ledge may be provided in the form of adhesive that overlaps the thin-film transistor ledge. A cover glass layer may form the outermost layer of the display to help protect the display. Gap filler adhesive may be interposed between the cover glass layer and portions of the thin-film transistor ledge to help support the thin-film transistor ledge. The use of gap filler adhesive can help reduce damage in the thin-film transistor ledge portion of the display during a drop event, but does not completely eliminate risk of damage.
It would therefore be desirable to be able to provide improved display structures for an electronic device display.
A display may be provided with a display layers and a backlight unit. The display layers may include a layer of liquid crystal material sandwiched between a color filter layer and a thin-film transistor layer. The thin-film transistor layer may have a ledge that is not overlapped by the color filter layer. Integrated circuits and a flexible printed circuit cable may be mounted on the thin-film transistor ledge.
The display layers may include an upper polarizer layer and a lower polarizer layer. The color filter layer, liquid crystal layer, and thin-film transistor layers may be interposed between the upper and lower polarizer layers. A display cover layer may overlap the display layers to serve as a protective layer.
Gap filler may be placed between the thin-film transistor ledge and the display cover layer to help prevent the ledge from bending upwards. Support structures may be placed between the thin-film transistor structures and the backlight unit to help prevent the ledge from bending downwards. The support structures may include an extended edge portion of the lower polarizer, a stiffener layer, gap filler, layers of adhesive, and other supporting structures.
An electronic device such as electronic device 10 of
Electronic device 10 may be a computing device such as 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, a device embedded in eyeglasses or other equipment worn on a user's head, 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. In the illustrative configuration of
In the example of
Display 14 may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures.
Display 14 may be protected using a display cover layer such as a layer of transparent glass, clear plastic, sapphire, or other transparent material. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button 16. An opening may also be formed in the display cover layer to accommodate ports such as speaker port 18. Openings may be formed in housing 12 to form communications ports (e.g., an audio jack port, a digital data port, etc.), to form openings for buttons, etc.
Display 14 may include an array of pixels formed from liquid crystal display (LCD) components, an array of electrophoretic pixels, an array of plasma pixels, an array of organic light-emitting diode pixels or other light-emitting diodes, an array of electrowetting pixels, or pixels based on other display technologies. Illustrative configurations for display 14 that are based on liquid crystal display structures are sometimes described herein as an example. This is, however, merely illustrative. Display 14 may use any suitable type of display technology.
The array of pixel in display 14 forms an active area AA. Active area AA is used to display images for a user of device 10. Active area AA may be rectangular or may have other suitable shapes. Inactive border area IA may run along one or more edges of active area AA. Inactive border area IA may contain circuits, signal lines, and other structures that do not emit light for forming images and does not contain any pixels. In some configurations for display 14, the widths of at least some of borders IA may be minimized or eliminated (e.g., to form a borderless display). For example, the borders of device 10 of
Display 14 may have an outermost layer such as display cover layer 26. Layer 26 may be formed from a transparent material that helps protect display 14 such as a layer of transparent plastic, clear glass, sapphire, or other protective display layer. Display module 28 (sometimes referred to as display structures) may contain pixels such as pixels 34. Pixels 34 may be arranged in a rectangular array of rows and columns or other suitable layouts to display images for a user of device 10. Pixels 34 produce images in active area AA of display 14. Inactive areas IA of display 14 do not contain pixels 34 and do not produce images. To block potentially unsightly interior components from view in device 10, the underside of the edges of display cover layer 26 may be coated with a layer of opaque masking material 24. Opaque masking material 24 may have the shape of a rectangular ring that surrounds a central rectangular active area AA or may have other suitable shapes. Opaque masking material 24 may be formed from a layer of black or white ink, metal, opaque plastic, or other opaque materials.
Display module 28 may have a backlight unit (sometimes referred to as backlight structures) for supplying display 14 with backlight illumination. A cross-sectional side view of an illustrative display module with a backlight unit is shown in
An illustrative backlight unit is shown in
Backlight unit 42 may include a light guide layer such as light guide layer 78. Light guide layer 78 may be formed from a transparent material such as clear glass or plastic (e.g., a molded clear plastic light guide plate or a thin flexible plastic light guide film). During operation of backlight unit 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 layer 78.
Light 74 from light source 72 may be coupled into edge surface 76 of light guide layer 78 and may be distributed in dimensions X and Y throughout light guide layer 78 due to the principal of total internal reflection. Light guide layer 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 layer 78.
Light 74 that scatters upwards in direction Z from light guide layer 78 may serve as backlight 44 for display 14. Light 74 that scatters downwards may be reflected back in the upward direction by a reflective film such as reflector 80. Reflector 80 may be formed from a reflective material such as a reflective layer of white plastic or other reflective materials.
To enhance backlight performance for backlight structures 42, backlight structures 42 may include optical films 70. Optical films 70 may include one or more diffuser layers for helping to homogenize backlight 44 and thereby reduce hotspots and one or more prism films (also sometimes referred to as turning films or brightness enhancement films) for collimating backlight 44. Compensation films for enhancing off-axis viewing may be included in optical films 70 or may be incorporated into other portions of display 14 (e.g., in polarizer layers such as layers 54 and/or 60). If desired, optical films 70 may include other layers of material (e.g., wave plates) and/or one or more of the layers of backlight unit 42 of
Illustrative display layers 46 for display module 28 are shown in
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 pixel-sized portions of 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 for display layers 46 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. For example, thin-film transistor layer 58 may include color filter elements and may be located above or below liquid crystal layer 52). Illustrative configurations for display 14 in which layer 58 is a thin-film transistor layer and layer 56 is a color filter 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 an array of pixels 34 of display 14 (e.g., display data). The information to be displayed may be conveyed to one or more display driver integrated circuits and other display driver circuitry (e.g., thin-film gate drivers, etc.) using a signal path such as a signal path formed from conductive metal traces in a rigid or flexible printed circuit. Backlight illumination 44 that is traveling outwards (vertically upwards in dimension Z in the orientation of
It may be desirable to provide thin-film transistor layer 58 with a portion that extends outward from under color filter layer 56 such as a region forming a thin-film transistor ledge. This ledge may contain contact pads coupled to thin-film transistor display driver circuitry and pixel circuits in the array of pixels 34. Display driver integrated circuits and/or flexible printed circuit cables may be coupled to the contact pads using solder and/or conductive adhesive (e.g., anisotropic conductive film). A perspective view of an illustrative region of thin-film transistor layer 58 that forms a ledge is shown in
Thin-film transistor ledge 106 contains components such as integrated circuits 100 and flexible printed circuit 102 and therefore does not contain any pixels 34 and does not display images (i.e., ledge 106 overlaps inactive area IA). Because ledge 106 extends outward from other layers 46 such as color filter layer 56, ledge 106 is less supported than other portions of thin-film transistor layer 58 and therefore may have an elevated risk of becoming damaged during a drop event. Ledge 106 forms a diving board structure that is prone to bending when device 10 is dropped and strikes a hard surface. Bending of this type may cause metal traces and other structures on thin-film transistor layer ledge 106 to crack, may cause solder joints for integrated circuits 100 to fail, may damage the anisotropic conductive film bonds formed between printed circuit 102 and the thin-film transistor layer contacts on ledge 106, and/or may otherwise damage thin-film transistor layer 58.
To help support ledge 106, gap filler 104 (e.g., drops of ultraviolet-light-cured or thermally cured epoxy or other adhesive) may be formed in corner regions of the upper surface of ledge 106. Gap filler 104 may couple thin-film transistor ledge 106 to the underside of display cover layer 26. Further support for ledge 106 may be provided on the opposing side of thin-film transistor layer 58 (e.g. on the lower side of ledge 106), as shown by illustrative support structures 122 of
Support structures 122 may be formed from one or more layers of material such as plastic, ceramic, glass, metal, or other suitable structures. As shown in
In the illustrative configuration of
If desired, support structures in the location of gap filler 104 may be formed using support structures such as support structures 122 of
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.
