PATENT DOCUMENT

Publication Number: US-11003015-B1
Application Number: US-201916285419-A
Country: US
Kind Code: B1

Title: Electronic device with a light guiding layer

Abstract:
A light guiding layer may be incorporated into an electronic device with multiple displays to create a seamless display surface between the adjacent displays. The light guiding layer may have a first portion that overlaps the active area of a first display panel, a second portion that overlaps the active area of a second, adjacent display panel, and a third portion that overlaps the inactive areas of the first and second display panels. The light guiding layer may redirect light from the active area of each display panel to the region above the inactive areas of the display panels where it is emitted towards the viewer. The light guiding layer therefore effectively hides the border between the two display panels by emitting light in that region. The light guiding layer may include light leakage promotion structures to ensure light is emitted in the border region.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a first display panel having a first active area; 
 a second display panel having a second active area, wherein the second display panel is adjacent to the first display panel; and 
 a light guiding layer that receives light from the first active area and the second active area, wherein the light guiding layer has an upper surface with a first portion that overlaps the first active area, wherein a first portion of the light passes through the first portion of the upper surface and exits the light guiding layer, and wherein a second portion of the light is reflected off the first portion of the upper surface to a region between the first and second active areas using total internal reflection. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the first display panel has a first inactive region, wherein the second display panel has a second inactive region, and wherein the first and second inactive regions are interposed between the first and second active areas. 
     
     
       3. The electronic device defined in  claim 2 , wherein the light guiding layer has a first portion that overlaps the first active area, a second portion that overlaps the second active area, and a third portion that is interposed between the first and second portions of the light guiding layer and that overlaps the first and second inactive regions. 
     
     
       4. The electronic device defined in  claim 3 , wherein the third portion of the light guiding layer has a center that is thinned relative to edges of the third portion of the light guiding layer. 
     
     
       5. The electronic device defined in  claim 1 , further comprising:
 a transparent layer that is formed over the first display panel, the second display panel, and the light guiding layer. 
 
     
     
       6. The electronic device defined in  claim 5 , wherein the transparent layer is a polarizer. 
     
     
       7. The electronic device defined in  claim 5 , further comprising:
 transparent filler that fills a gap between the first and second display panels and the transparent layer. 
 
     
     
       8. The electronic device defined in  claim 1 , further comprising:
 a layer of adhesive that attaches the light guiding layer to the first and second display panels. 
 
     
     
       9. The electronic device defined in  claim 1 , wherein the first and second display panels are separated by an angle that is between 20 degrees and 160 degrees. 
     
     
       10. The electronic device defined in  claim 9 , wherein the angle is between 80 degrees and 100 degrees. 
     
     
       11. An electronic device comprising:
 a first display panel having a first active area and a first inactive area; 
 a second display panel having a second active area and a second inactive area, wherein the first and second inactive areas are interposed between the first and second active areas; and 
 a light guiding layer that receives light from the first active area and the second active area, wherein the light guiding layer has a first portion that overlaps the first active area, a second portion that overlaps the second active area, and a third portion that is interposed between the first and second portions and that overlaps the first and second inactive areas, wherein the first and second portions transmit a first portion of the light and redirect a second portion of the light to the third portion using total internal reflection, wherein the third portion of the light guiding layer has an upper surface and a lower surface, wherein the light guiding layer includes light leakage promotion structures on the upper surface, and wherein the light guiding layer includes light redirecting structures on the lower surface. 
 
     
     
       12. The electronic device defined in  claim 11 , wherein the light leakage promotion structures comprise lenticular ridges that each extend along a respective longitudinal axis. 
     
     
       13. The electronic device defined in  claim 11 , wherein the light leakage promotion structures comprise an array of microlenses on the upper surface. 
     
     
       14. The electronic device defined in  claim 11 , wherein a first portion of the light leakage promotion structures has a first density and a second portion of the light leakage promotion structures has a second density that is different than the first density. 
     
     
       15. The electronic device defined in  claim 11 , wherein the light redirecting structures comprise recesses in the lower surface of the light guiding layer. 
     
     
       16. The electronic device defined in  claim 11 , wherein the light leakage promotion structures are formed on the upper surface in the third portion but not the first and second portions, and wherein the light redirecting structures are formed on the lower surface in the third portion but not the first and second portions. 
     
     
       17. An electronic device comprising:
 a first display panel having a first active area; 
 a second display panel having a second active area, wherein the second display panel is adjacent to the first display panel; and 
 a light guiding layer having a first portion that receives light from the first active area and a second portion that receives light from the second active area, wherein the first portion has a first angled surface that redirects a first subset of the light from the first active area to a region between the first and second active areas using total internal reflection, wherein a second subset of the light from the first active area passes through the first angled surface, wherein the second portion has a second angled surface that redirects a first subset of the light from the second active area to the region between the first and second active areas using total internal reflection, and wherein a second subset of the light from the second active area passes through the second angled surface. 
 
     
     
       18. The electronic device defined in  claim 17 , wherein the light guiding layer comprises a third portion that is interposed between the first and second portions, wherein the third portion has an upper surface that is interposed between the first and second angled surfaces, wherein the third portion has a lower surface, and wherein the third portion of the light guiding layer has light leakage promotion structures on the upper surface and light redirecting structures on the lower surface.

Description:
This application claims priority to U.S. provisional patent application No. 62/638,806 filed on Mar. 5, 2018, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates to electronic devices, and, more particularly, to electronic devices with displays. 
     BACKGROUND 
     Electronic devices such as laptop computers, cellular telephones, and other equipment may include displays. Displays in electronic devices may have an active area that is surrounded by an inactive area. The active area may include pixels that emit light that is viewable by a user, whereas the inactive area does not emit light that is viewable by a user. Some electronic devices may include more than one display. 
     If care is not taken, electronic devices with multiple displays may have undesirable seams between the displays. For example, the inactive area of the displays may result in a portion between the displays that does not emit light that is viewable by the user. 
     SUMMARY 
     An electronic device may be provided with more than one display in a housing. Each display may have an array of pixels that form an active area for displaying images. Each display may have an inactive area containing circuitry such as display driver circuitry or gate driver circuitry that surrounds the active area. Adjacent displays in the electronic device may therefore have a border region between them that cannot display images. 
     To create a seamless display surface between the adjacent displays, a light guiding layer may be provided. The light guiding layer may have a first portion that overlaps the active area of a first display panel, a second portion that overlaps the active area of a second, adjacent display panel, and a third portion that overlaps the inactive areas of the first and second display panels. The light guiding layer may redirect light from the active area of each display panel to the region above the inactive areas of the display panels where it is emitted towards the viewer. The light guiding layer therefore effectively hides the border between the two display panels (by emitting light in that region). 
     The light guiding layer may include light leakage promotion structures to ensure light is emitted in the border region. For example, the light guiding layer may have lenticular ridges on an upper surface that cause light to be emitted upon reaching the upper surface of the light guiding layer. Additionally, the light guiding layer may have recesses on a lower surface that redirect light towards the light leakage promotion structures on the upper surface. 
     The light guiding layer may be used to hide a border region between adjacent displays that are coplanar. Alternatively, the light guiding layer may be used to hide a border region between adjacent displays that are at an angle (e.g., 90-degree angle) relative to each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view of an illustrative electronic device having two adjacent displays and a light guiding layer to hide the border region between the two adjacent displays in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative light guiding layer of the type shown in  FIG. 2  in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of illustrative light leakage promotion structures that may be incorporated on an upper surface of a light guiding layer such as the light guiding layer of  FIG. 3  in accordance with an embodiment. 
         FIG. 5  is a top view of illustrative light leakage promotion structures for a light guiding layer that extend along a longitudinal axis such as the light leakage promotion structures of  FIG. 4  in accordance with an embodiment. 
         FIG. 6  is a top view of illustrative light leakage promotion structures for a light guiding layer that are formed as dots on the light leakage layer in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of illustrative light leakage promotion structures that may be incorporated on a lower surface of a light guiding layer such as the light guiding layer of  FIG. 3  in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative light guiding layer having light leakage promotion structures with a varying density profile in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of an illustrative electronic device having two adjacent displays at a 90-degree angle relative to each other and a light guiding layer to hide the border region between the two adjacent displays in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices can be provided with one or more displays. The displays may, if desired, be positioned adjacent to each other in the electronic device. Each display may have an inactive area that extends around at least a portion of the border of the display. Therefore, when two displays are positioned next to each other, the inactive area of the displays may be positioned between the two displays. This inactive area between the displays does not include pixels that emit light and may be referred to as a seam between the two displays. To enable light to be displayed from the seam between the two displays, a light guiding layer may be provided. The light guiding layer may take light from the active areas of the adjacent displays and emit the light, effectively hiding the seam between the two displays. 
     An illustrative electronic device of the type that may be provided with multiple displays is shown in  FIG. 1 . 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&#39;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. Illustrative configurations in which electronic device  10  is a portable electronic device may sometimes be described herein as an example. This is, however, merely illustrative. Electronic device  10  may be any suitable electronic equipment. 
     As shown in  FIG. 1 , electronic device  10  may have control circuitry  20 . Control circuitry  20  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  20  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Control circuitry  20  may include wired and/or wireless communications circuitry. The wireless communications circuitry of circuitry  20  may include one or more antennas and one or more radio-frequency transceiver circuits (e.g., a cellular telephone transceiver, a wireless local area network transceiver, etc.). 
     Input-output circuitry in device  10  such as input-output devices  22  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  22  may include buttons, joysticks, scrolling wheels, key pads, keyboards, tone generators, haptic output devices such as vibrators, light-emitting diodes and other status indicators, data ports, etc. Input-output devices  22  may also include sensors  24 . Audio output (sound) may be provided using one or more speakers such as speakers  26 . 
     Input-output devices  12  may include one or more displays  14 . Each display may be a touch screen display that includes a touch sensor for gathering touch input from a user or each display may be insensitive to touch. A touch sensor for display  14  may be based on an array of capacitive touch sensor electrodes, acoustic touch sensor structures, resistive touch components, force-based touch sensor structures, a light-based touch sensor, or other suitable touch sensor arrangements. 
     Sensors  24  may include touch sensors (e.g., capacitive touch sensors formed from arrays of capacitive touch sensor electrodes that overlap one or more of displays  14  and/or that are formed elsewhere in device  10 ), microphones for gathering ambient noise measurements and voice commands, a magnetic sensor (e.g., a compass), an accelerometer, a gyroscope, a force sensor (e.g., a two-dimensional force sensor which may optionally overlap a touch sensor and/or display  14 ), a temperature sensor, a pressure sensor, a compass, etc. Sensors  24  may also include light-based sensors such as a light-based proximity sensor (e.g., an optical proximity sensor having an infrared light-emitting diode that emits light and having a corresponding infrared light detector for measuring the infrared light after the infrared light has reflected from an external object), an ambient light sensor (e.g., a color-sensitive ambient light sensor that can measure ambient light color and intensity), and a camera (e.g., a digital image sensor) for capturing images, and/or other image sensing and/or light-detecting devices. Input-output devices  22  may also include light-emitting diodes (e.g., status indicator lights, a camera flash, etc.) and/or other light-emitting devices. Light-based (optical) components such as these (e.g., light-emitting device and/or light-based sensors) may be mounted under transparent window regions (e.g., a transparent window in a portion of display  14 , a transparent window in a device housing, etc.). 
     A cross-sectional side view of an illustrative electronic device including multiple displays is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  includes a first display  14 A and a second display  14 B. The first display includes a display panel  28 A having display pixels  32  in a corresponding active area  34 A. Display pixels  32  in active area  34 A may generate light that is emitted towards viewer  30 . The active area of display  14 A may be surrounded by a corresponding inactive area  36 A. Inactive area  36 A may include display circuitry (e.g., gate driver circuitry, display driver circuitry, etc.). However, inactive area  36 A does not include pixels. The second display ( 14 B) also includes a display panel  28 B having display pixels  32  in a corresponding active area  34 B. Display pixels  32  in active area  34 B may generate light that is emitted towards viewer  30 . The active area of display  14 B may be surrounded by a corresponding inactive area  36 B. Inactive area  36 B may include display circuitry (e.g., gate driver circuitry, display driver circuitry, etc.). However, inactive area  36 B does not include pixels. The inactive areas  36 A and  36 B may collectively be referred to as a single inactive area, inactive region, or border region. 
     Pixels  32  may be formed from liquid crystal display (LCD) components, organic light-emitting diode structures, plasma display structures, electrowetting display structures, electrophoretic display structures, or other desired display pixel structures. Each respective display in electronic device  10  may have any desired type of display pixels (e.g., the displays may have display pixels of the same types or display pixels of different types). 
     As previously discussed, inactive area  36 A of display panel  28 A and inactive area  36 B of display panel  28 B do not include display pixels and therefore do not emit light towards viewer  30 . However, it may be desirable for light to be emitted in this region, thereby forming a seamless display surface (including displays  14 A and  14 B) despite the presence of the inactive region between the display active areas. Electronic device  10  may therefore include light guiding layer  42  to guide light from the edge of the active areas of the displays to the inactive region between the displays. 
     As shown in  FIG. 2 , light guiding layer  42  may be attached to the upper surface of display panels  28 A and  28 B. In the embodiment shown, light guiding layer  42  is attached to the upper surface of the display panels using adhesive  44 . Adhesive  44  may be transparent (e.g., an optically clear adhesive). 
     As shown, light guiding layer  42  may overlap the active areas of displays  14 A and  14 B. A first portion of the light guiding layer overlaps (and is attached to) active area  34 A of display panel  28 A. A second portion of the light guiding layer overlaps (and is attached to) active area  34 B of display panel  28 B. A third portion of the light guiding layer (that is interposed between the first and second portions) overlaps (and is attached to) the inactive area  36 A of display panel  28 A and the inactive area  36 B of display panel  28 B. Light may enter light guiding layer  42  from active area  34 A and active area  34 B. Consider light  50  that is emitted from a pixel in active area  34 A. The light may be emitted from the pixel and pass into the light guiding layer. Light  50  may be reflected off of surfaces of the light guiding layer (e.g., in the positive X-direction) and travel towards the border region between the two active areas. Then, light leakage promotion structures may cause light  50  to exit the light guiding layer (in a direction towards viewer  30 ). In this way, light from the edge of the active areas may be redirected and emitted from the border region between the display active areas. This can ensure a seamless display surface with display light emitted across the entire display surface. 
     Display panels  28 A and  28 B may be covered by one or more transparent layers.  FIG. 2  shows an example where transparent layers  52 - 1  and  52 - 2  cover display panels  28 A and  28 B as well as light guiding layer  42 . Transparent layers  52 - 1  and  52 - 2  may be any desired layers. For example, each transparent layer may be a polarizer layer, a color filter layer, a dielectric cover layer, a touch sensor layer, or another desired display layer. In the example of  FIG. 2 , transparent layer  52 - 2  may be a polarizer layer and transparent layer  52 - 1  may be a dielectric cover layer. For example, polarizer layer  52 - 2  may be a polarizer (e.g., a linear polarizer) that serves as an upper polarizer for a liquid crystal display (e.g., pixels  32  may be liquid crystal display pixels). In another example, polarizer layer  52 - 2  may be a polarizer (e.g., a linear polarizer) that serves as a portion of a circular polarizer for a light-emitting diode display (e.g., pixels  32  may be light-emitting diode display pixels). Dielectric cover layer  52 - 1  may serve as an exterior layer for the electronic device. The dielectric cover layer may be formed from glass and may sometimes be referred to as a cover glass or a cover glass layer. 
     The space between transparent layer  52 - 2  (e.g., the layer above light guiding layer  42 ) and display panels  28 A and  28 B may be filled with any desired material  54 . In one illustrative embodiment, the space between transparent layer  52 - 2  and display panels  28 A and  28 B may be filled with air (e.g., an air-gap). In another illustrative embodiment, optically clear adhesive (OCA)  54  may fill the gap between the display panels and the transparent layer. This example is merely illustrative. In general, any desired transparent material  54  (sometimes referred to as transparent filler) may fill this space. 
     Material  54  may have a lower index of refraction than light guiding layer  42 . Light guiding layer  42  may be formed from a material with a high index of refraction. For example, light guiding layer  42  may be formed from glass, polycarbonate, or another desired transparent polymer. Light guiding layer  42  may have an index of refraction that is greater than 1.5, greater than 1.3, greater than 1.1, greater than 1.7, less than 2.0, less than 1.5, less than 1.7, between 1.3 and 2.0, between 1.3 and 1.7, or another desired index of refraction. In contrast, material  54  that surrounds light guiding layer  42  may have an index of refraction that is less than 1.1, less than 1.2, less than 1.3, less than 1.4, less than 1.5, greater than 1.0, greater than 1.2, between 1.0 and 1.3, or another desired index of refraction. The index of refraction of light guiding layer  42  may be greater than the index of refraction of material  54 . The difference between the indices of refraction may be greater than 0.2, greater than 0.3, greater than 0.4, greater than 0.5, less than 0.5, between 0.2 and 0.7, or any other desired difference. 
     The example of  FIG. 2  where light guiding layer  42  is attached to the display panels with adhesive is merely illustrative. Light guiding layer  42  may additionally or instead have adhesive attaching the light guiding layer to transparent layer  52 - 2 . Any desired arrangement may be used to incorporate light guiding layer  42  into the electronic device. 
     Light guiding layer  42  may include light leakage promotion structures to increase the amount of light that is emitted in the border region between the two displays. As shown in  FIG. 2 , light guiding layer  42  includes a first plurality of light leakage promotion structures  62  on the upper surface of the light guiding layer and a second plurality of light redirecting structures (sometimes also referred to as light leakage promotion structures)  64  on the lower surface of the light guiding layer. These light leakage promotion structures may include protrusions and/or recesses of any desired shapes to help light ultimately exit the light guiding layer over inactive areas  34 A and  34 B. The light leakage promotion structures are shown in more detail in  FIG. 3 . 
       FIG. 3  is a cross-sectional side view of an illustrative light guiding layer of the type that may be included in  FIG. 2 . As shown, light guiding layer  42  includes a first portion  42 - 1 , a second portion  42 - 2 , and a third portion  42 - 3 . Portions  42 - 1  and  42 - 3  may be referred to as wedge portions. Portions  42 - 1  and  42 - 3  may overlap the active areas of respective displays. Portion  42 - 2  is interposed between portions  42 - 1  and  42 - 3  and may be referred to as a light leakage region. Portion  42 - 2  overlaps the inactive region between the displays and includes light leakage promotion structures to ensure sufficient emission of light over the inactive region. 
     Wedge portion  42 - 1  has a planar upper surface  72  that is at an angle  74  relative to planar lower surface  66 . Light may be emitted from the active area of a display through lower surface  66  into wedge portion  42 - 1 . Some of the light (e.g., on-axis light) may be transmitted through surface  72 . However, some of the light (e.g., off-axis light) may be reflected off of surface  72  due to total internal reflection (TIR). Angle  74  may be any desired angle and may be selected to control how much light is reflected towards portion  42 - 2 . 
     Similarly, wedge portion  42 - 3  has a planar upper surface  76  that is at an angle  78  relative to planar lower surface  66 . Light may be emitted from the active area of a display through lower surface  66  into wedge portion  42 - 3 . Some of the light (e.g., on-axis light) may be transmitted through surface  76 . However, some of the light (e.g., off-axis light) may be reflected off of surface  76  due to total internal reflection (TIR). Angle  78  may be any desired angle and may be selected to control how much light is reflected towards portion  42 - 2 . 
     Wedge portion  42 - 1  may have any desired width  80 . Width  80  may correspond to the amount of light guiding layer  42  that overlaps the active area of a first display (e.g., active area  34 A in  FIG. 2 ). Width  80  may be between 1 millimeters and 2 millimeters, greater than 0.5 millimeters, greater than 1 millimeter, greater than 2 millimeters, greater than 0.1 millimeters, greater than 10 millimeters, less than 0.5 millimeters, less than 1 millimeter, less than 2 millimeters, less than 0.1 millimeters, less than 10 millimeters, about (e.g., within 10% of) 1.6 millimeters, etc. Wedge portion  42 - 3  may have the same width as wedge portion  42 - 1  or a different width than wedge portion  42 - 1 . 
     Wedge portion  42 - 1  may have a height (thickness)  82 . Height  82  may correspond to the height of the thickest portion of the light guiding layer. Height  82  may be between 0.1 millimeters and 1.0 millimeters, greater than 0.1 millimeters, greater than 0.2 millimeter, greater than 0.5 millimeters, greater than 0.01 millimeters, greater than 1.0 millimeter, greater than 10 millimeters, less than 0.1 millimeters, less than 0.2 millimeter, less than 0.5 millimeters, less than 0.01 millimeters, less than 1.0 millimeter, less than 10 millimeters, about (e.g., within 10% of) 0.3 millimeters, etc. Wedge portion  42 - 3  may the same height as wedge portion  42 - 1  or a different height than wedge portion  42 - 1 . 
     Light leakage portion  42 - 2  of light guiding layer  42  has a width  86 . Width  86  may correspond to the distance between the active areas of the adjacent displays (e.g., the width of the border region). Width  86  may be between 1 millimeters and 5 millimeters, between 3 and 4 millimeters, greater than 1 millimeter, greater than 2 millimeters, greater than 3 millimeters, greater than 5 millimeters, greater than 10 millimeters, less than 1 millimeter, less than 2 millimeters, less than 3 millimeters, less than 5 millimeters, less than 10 millimeters, about (e.g., within 10% of) 3.2 millimeters, etc. 
     Light guiding layer may have a height (thickness)  84  at the center of the light guiding layer (e.g., at the center of portion  42 - 2 ). The light guiding layer may be thinned in the center of the light guiding layer to control light leakage. For example, if light guiding layer  42  covers two adjacent and coplanar displays, the light guiding layer may be thinned to increase light leakage over the inactive region between the displays. Height  84  may therefore be less than height  82 . Height  84  may be may be between 0.05 millimeters and 0.2 millimeters, greater than 0.05 millimeters, greater than 0.1 millimeter, greater than 0.2 millimeters, greater than 0.5 millimeters, greater than 0.01 millimeters, greater than 1.0 millimeter, greater than 10 millimeters, less than 0.05 millimeters, less than 0.1 millimeters, less than 0.2 millimeter, less than 0.5 millimeters, less than 0.01 millimeters, less than 1.0 millimeter, less than 10 millimeters, about (e.g., within 10% of) 0.1 millimeters, etc. Heights  82  and  84  may differ by a factor of greater than 1, greater than 2, greater than 1.5, greater than 2.5, greater than 3, or another desired factor. 
     Light guiding layer  42  also includes light leakage promotion structures. First, light guiding layer  42  has light leakage promotion structures  62  on an upper surface of the light guiding layer. In particular, the light leakage promotion structures are formed on the upper surface of portion  42 - 2  of the light guiding layer. The light leakage promotion structures may be formed from the same material as the rest of the light guiding layer or a different material than the rest of the light guiding layer. Light leakage promotion structures  62  may be lenticular lenses, microlenses, or other structures that promote light leakage in portion  42 - 2 . It is desirable for light to exit light guiding layer  42  in portion  42 - 2  (so that the light is emitted from the border region). Without structures  62 , light might reflect off of the upper surface of the light guiding layer in portion  42 - 2  (due to total internal reflection) and not exit the light guiding layer in portion  42 - 2 . The presence of structures  62  may cause light that reaches the upper surface of portion  42 - 2  to exit the light guiding layer. 
     Light guiding layer  42  also has light leakage promotion structures  64  on a lower surface of the light guiding layer. Light leakage promotion structures  64  may be recesses in the lower surface of the light guiding layer that form a turning film. Light leakage promotion structures  64  may reflect light that reaches the lower surface of portion  42 - 2  towards the upper surface of portion  42 - 2  (increasing the likelihood of the light exiting light guiding layer  42  in portion  42 - 2 ). 
     In general, structures  62  and  64  may be any desired structures. In one possible embodiment, light leakage promotion structures  62  may be formed by lenticular lenses that extend along the length of the light guiding layer. 
       FIG. 4  is a cross-sectional side view showing lenticular lenses  62  (sometimes referred to as lenticular ridges  62 ). As shown in  FIG. 4 , lenticular ridges  62  may have a semicircular cross-sectional shape. This example is merely illustrative, however. In general, the cross-section of ridges  62  may have any desired shape. Each ridge may extend along a longitudinal axis along the length of the light guiding layer (e.g., into or out of the page in  FIG. 4 , parallel to the Y-axis). Each ridge may have a base width  90 . The base width may be between 25 microns and 75 microns, between 20 microns and 100 microns, greater than 10 microns, greater than 30 microns, greater than 50 microns, greater than 80 microns, greater than 100 microns, greater than 1000 microns, less than 10 microns, less than 30 microns, less than 50 microns, less than 80 microns, less than 100 microns, less than 1000 microns, about (e.g., within 10% of) 50 microns, etc. Similarly, the ridges may have any desired spacing  94  (e.g., between 25 microns and 75 microns, between 20 microns and 100 microns, greater than 10 microns, greater than 30 microns, greater than 50 microns, greater than 80 microns, greater than 100 microns, greater than 1000 microns, less than 10 microns, less than 30 microns, less than 50 microns, less than 80 microns, less than 100 microns, less than 1000 microns, about 50 microns, etc.) and angle  92  of the curved upper surface of the ridge relative to the X-axis (e.g., between 40 degrees and 50 degrees, between 15 degrees and 30 degrees, between 10 degrees and 50 degrees, more than 10 degrees, more than 20 degrees, more than 45 degrees, more than 65 degrees, less than 10 degrees, less than 20 degrees, less than 45 degrees, less than 65 degrees, about 20 degrees, etc.). The dimensions and spacing of each ridge  62  may be the same across the light guiding layer or may vary across the light guiding layer. 
       FIG. 5  is a top view of light spreading layer  42  showing how lenticular ridges  62  extend parallel to the Y-axis. As shown, light spreading layer  42  overlaps active area  34 A and inactive area  36 A of display  14 A as well as active area  34 B and inactive area  36 B of display  14 B. The border region formed by inactive areas  36 A and  36 B extends between the displays along the Y-axis. Light leakage promotion structures  62  may also extend parallel to the Y-axis. 
     The example in  FIG. 5  of light leakage promotion structures  62  being lenticular ridges that extend along a longitudinal axis is merely illustrative. Other structures may be used for light leakage promotion structures if desired. For example,  FIG. 6  is a top view of a light spreading layer  42  having light leakage promotion dots  62 . Each extraction dot  62  (sometimes referred to as a microlens) may have any desired cross-section (e.g., the same cross-section shown in  FIG. 4 , for example). The lenticular ridges of  FIG. 5  may spread light relative to one axis, whereas the extraction dots of  FIG. 6  may spread light relative to two axes. The extraction dots may have any desired outline or shape. 
       FIG. 7  is a cross-sectional side view of light spreading layer  42  showing how light leakage promotion structures  64  may be formed from recesses in the light spreading layer. As shown in  FIG. 7 , the recesses  64  may have a triangular cross-sectional shape. This example is merely illustrative, however. In general, the cross-section of recesses  64  may have any desired shape. Each recess (sometimes referred to as a groove) may extend along a longitudinal axis along the length of the light guiding layer, similar to the ridges shown in  FIG. 5  (e.g., into or out of the page in  FIG. 7 , parallel to the Y-axis). Each recess may have a base width  96 . The base width may be between 25 microns and 75 microns, between 20 microns and 100 microns, greater than 10 microns, greater than 30 microns, greater than 50 microns, greater than 80 microns, greater than 100 microns, greater than 1000 microns, less than 10 microns, less than 30 microns, less than 50 microns, less than 80 microns, less than 100 microns, less than 1000 microns, about (e.g., within 10% of) 50 microns, etc. Similarly, the recesses (sometimes referred to as prisms) may have any desired spacing  100 . For example, distance  100  may be between 25 microns and 75 microns, between 20 microns and 100 microns, greater than 10 microns, greater than 30 microns, greater than 50 microns, greater than 80 microns, greater than 100 microns, greater than 1000 microns, less than 10 microns, less than 30 microns, less than 50 microns, less than 80 microns, less than 100 microns, less than 1000 microns, about 50 microns, etc. Moreover, light guiding layer  42  may have a planar surface that defines the recess and is at angle  98  relative to the X-axis. Angle  98  may be between 40 degrees and 50 degrees, between 15 degrees and 30 degrees, between 10 degrees and 50 degrees, more than 10 degrees, more than 20 degrees, more than 45 degrees, more than 65 degrees, less than 10 degrees, less than 20 degrees, less than 45 degrees, less than 65 degrees, about 20 degrees, about 45 degrees etc. 
     Recesses  64  in  FIG. 7  may be filled with any desired material. In some cases, the recesses may be filled with air. In other embodiments, an optically clear adhesive or other transparent or opaque material may fill the recesses. The recesses may form a turning film surface that directs light in the positive Z-direction. The dimensions and spacing of each recess  64  may be the same across the light guiding layer or may vary across the light guiding layer. 
     To further control how light is emitted from light guiding layer, light leakage promotion structures  62  and/or  64  may have a varied density across the light guiding layer.  FIG. 8  is a cross-sectional side view of an illustrative light guiding layer that has light leakage promotion structures with varying density. As shown in  FIG. 8 , light leakage promotion structures  62  have a first region  102  with a first density (e.g., number of structures per unit of surface area of the light guiding layer), a second region  104  with a second density, and a third region  106  with a second density. The second density may be higher than the first and third densities. By having the higher density area in the center of the light guiding layer, it can be assured that light from the active area is distributed throughout the light guiding layer (and does not all exit the light guiding layer before reaching the center of the light guiding layer). 
     As shown in  FIG. 8 , light leakage promotion structures  64  have a first region  112  with a first density (e.g., number of recesses per unit of surface area of the light guiding layer), a second region  114  with a second density, and a third region  116  with a second density. The second density may be higher than the first and third densities. By having the higher density area in the center of the light guiding layer, it can be assured that light from the active area is distributed throughout the light guiding layer (and does not all exit the light guiding layer before reaching the center of the light guiding layer). 
     In general, both light leakage promotion structures  62  and  64  may have any desired density profile (with any number of regions each having any desired density). The density profile may change smoothly or step-wise between different densities. Structures  62  and  64  may have the same density profile or different density profiles. 
     In the aforementioned embodiments, light guiding layer  42  is used to hide a border region between two adjacent and coplanar displays. This example is merely illustrative, however. Light guiding layer  42  may be used to hide a border region between two adjacent displays that are positioned at any angle relative to each other.  FIG. 9  is a cross-sectional side view of illustrative displays that are positioned at an angle relative to each other. As shown in  FIG. 9 , display panel  28 A extends along longitudinal axis  118 , whereas display panel  28 B extends along longitudinal axis  120 . Axes  118  and  120  are separated by angle  122 . In the embodiment of  FIG. 9 , angle  122  is 90 degrees. Axis  118  is parallel to the X-axis (and display panel  28 A emits light in the positive Z-direction), whereas axis  120  is parallel to the Z-axis (and display panel  28 B emits light in the positive X-direction). 
     Similar to as described in connection with  FIG. 2 , each display panel may have a corresponding inactive area ( 36 A and  36 B). The inactive areas  36 A and  36 B may collectively be referred to as a single inactive area, inactive region, or border region. As shown, light guiding layer  42  may overlap the active areas of displays  14 A and  14 B. A first portion of the light guiding layer overlaps (and is attached to) active area  34 A of display panel  28 A. A second portion of the light guiding layer overlaps (and is attached to) active area  34 B of display panel  28 B. A third portion of the light guiding layer (that is interposed between the first and second portions) overlaps (and is attached to) the inactive area  36 A of display panel  28 A and the inactive area  36 B of display panel  28 B. Light may enter light guiding layer  42  from active area  34 A and active area  34 B. Then, light leakage promotion structures may cause the light to exit the light guiding layer in the border region between the display active areas. This can ensure a seamless display surface with display light emitted across the entire display surface. 
     Light guiding layer  42  in  FIG. 9  includes light leakage promotion structures  62  and  64  (as described above in connection with  FIGS. 2-8 ). The dimensions, shapes, and density profiles of the light leakage promotion structures may be selected based on the angle  122  between the two displays (e.g., to optimize how light is emitted from the light guiding layer).  FIG. 9  shows heights  82  and  84  of light guiding layer  42  (similar to as discussed in connection with  FIG. 3 ). In  FIG. 3 , it was described how the center of the light guiding layer (e.g., height  84 ) may be thinned to promote light leakage. This example is merely illustrative, however. The ratio of height  84  to height  82  may be dependent upon angle  122  between the displays. As shown in  FIG. 9 , when angle  122  is 90 degrees, height  84  may be equal to height  82 . Again, heights  82  and  84  may generally have any desired values. 
     The example in  FIG. 9  of angle  122  being 90 degrees is merely illustrative. In general, angle  122  may be greater than 40 degrees, greater than 60 degrees, greater than 80 degrees, between 80 degrees and 100 degrees, between 40 degrees and 140 degrees, between 20 degrees and 160 degrees, greater than 100 degrees, greater than 120 degrees, 180 degrees (e.g., coplanar), less than 40 degrees, less than 60 degrees, less than 80 degrees, less than 100 degrees, less than 120 degrees, about (e.g., within 10% of) 90 degrees, or any other desired angle. Additionally, the example of  FIG. 2  and  FIG. 9  of light guiding layer  42  hiding a seam between two displays is merely illustrative. Light guiding layer  42  may hide a seam between any desired number of displays (e.g., two, three, more than three, etc.). The displays in  FIG. 9  may also include the transparent filler material  54 , transparent substrate  52 - 1 , and/or transparent substrate  52 - 2  as described in connection with  FIG. 2 . 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20190226
Publication Date: 20210511
Grant Date: 20210511
Priority Date: 20180305
Inventors: QIAO, YI
GUILLOU, JEAN-PIERRE S
BROWN, MICHAEL J.
XU, MING
KAKUDA, TYLER R.
Assignee: APPLE INC
CPC Classifications: [{"code": "H10H29/142", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10H20/855", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10H20/84", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133526", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133524", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13336", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0078", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133524", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13336", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L27/156", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L33/58", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L51/5281", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L33/44", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L27/3293", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0078", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133524", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13336", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K50/86", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/8791", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 75845923