PATENT DOCUMENT

Publication Number: US-11105677-B2
Application Number: US-201816141183-A
Country: US
Kind Code: B2

Title: Electronic devices with switchable diffusers

Abstract:
An electronic device may be provided with a display. An optical component window may be formed in the inactive area of the display. The optical component window may transmit infrared light from an infrared light source. The infrared light source may include a diffuser to allow the light source to operate in a flood illumination mode and a structured light mode. The diffuser may include liquid crystal material between first and second substrates. A sealant may surround the liquid crystal layer, and one or more spacer walls may be located between the sealant and the liquid crystal layer. An additional spacer wall may be used outside of the sealant to prevent metal from creating an electrical short between electrodes in the diffuser. Conductive material in the sealant may be used to couple a top electrode to a metal pad on a bottom substrate.

Claims:
What is claimed is: 
     
       1. A diffuser, comprising:
 first and second transparent substrates; 
 liquid crystal material between the first and second substrates; 
 a sealant surrounding the liquid crystal material; and 
 inner and outer spacer walls interposed between the liquid crystal material and the sealant, wherein the outer spacer wall contacts the sealant and the inner spacer wall has at least one opening. 
 
     
     
       2. The diffuser defined in  claim 1  wherein the inner and outer spacer walls are separated by a gap. 
     
     
       3. The diffuser defined in  claim 1  wherein the inner and outer spacer walls comprise polymer. 
     
     
       4. The diffuser defined in  claim 1  wherein the outer spacer wall forms a continuous perimeter. 
     
     
       5. The diffuser defined in  claim 4  wherein the continuous perimeter is rectangular. 
     
     
       6. The diffuser defined in  claim 1  further comprising a first electrode formed only on the first substrate and a second electrode having a first portion formed on the first substrate and a second portion formed on the second substrate. 
     
     
       7. The diffuser defined in  claim 6  further comprising a conductive material within the sealant that electrically couples the first portion of the second electrode to the second portion of the second electrode. 
     
     
       8. The diffuser defined in  claim 7  further comprising a passivation layer that covers the first electrode. 
     
     
       9. The diffuser defined in  claim 8  wherein the passivation layer has openings and wherein the conductive material is coupled to the second portion of the second electrode through the openings in the passivation layer. 
     
     
       10. The diffuser defined in  claim 1  wherein the at least one opening in the inner spacer wall comprises first and second openings. 
     
     
       11. The diffuser defined in  claim 10  wherein the outer spacer wall has third and fourth openings that are offset from the first and second openings. 
     
     
       12. The diffuser defined in  claim 11  wherein at least some of the liquid crystal material is located between the inner spacer wall and the outer spacer wall. 
     
     
       13. An infrared light source operable in a structured light mode and a flood illumination mode, comprising:
 an infrared light emitter that emits infrared light; and 
 a diffuser formed over the infrared light emitter, wherein the diffuser is configured to diffuse the infrared light in the flood illuminate mode and to transmit the infrared light unaltered in the structured light mode, and wherein the diffuser comprises:
 a liquid crystal layer; 
 a spacer surrounding the liquid crystal layer; and 
 a sealant surrounding the spacer and the liquid crystal layer, wherein the spacer contacts the sealant. 
 
 
     
     
       14. The infrared light source defined in  claim 13  wherein the spacer comprises acrylic. 
     
     
       15. The infrared light source defined in  claim 13  further comprising an additional spacer between the liquid crystal layer and the spacer. 
     
     
       16. The infrared light source defined in  claim 15  wherein the spacer comprises a continuous perimeter of material and the additional spacer has gaps. 
     
     
       17. The infrared light source defined in  claim 13  wherein the infrared light emitter comprises a laser. 
     
     
       18. A diffuser, comprising:
 first and second substrates; 
 a liquid crystal layer between the first and second substrates; 
 a first electrode on the first substrate; 
 a second electrode on the second substrate; 
 sealant surrounding the liquid crystal layer, wherein the sealant includes a conductive material coupled to the first electrode; and 
 a spacer contacting the sealant that separates the sealant from the liquid crystal layer. 
 
     
     
       19. The diffuser defined in  claim 18  further comprising an additional spacer, wherein the sealant is interposed between the spacer and the additional spacer. 
     
     
       20. The diffuser defined in  claim 18  further comprising first and second metal pads on the second substrate, wherein the first metal pad is electrically coupled to the first electrode on the first substrate and the second metal pad is electrically coupled to the second electrode on the second substrate. 
     
     
       21. The diffuser defined in  claim 18  further comprising a passivation layer that covers the second electrode, wherein the passivation layer has openings to allow the conductive material to contact the first electrode.

Description:
This application claims the benefit of provisional patent application No. 62/582,206, filed Nov. 6, 2017, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to electronic devices, and, more particularly, to electronic devices with optical components such as diffusers. 
     BACKGROUND 
     Electronic devices such as laptop computers, cellular telephones, and other equipment are sometimes provided with light-based components such as light-emitting diodes, lasers, cameras, light sensors, and other light-emitting and light-detecting components. 
     Optical systems may be incorporated into an electronic device to help manipulate light associated with light-based components. For example, an optical system may be included in an electronic device to diffuse light, to filter light, to focus or collimate light, or to otherwise manipulate light that is being emitted or detected with light-based components. In some situations, optical systems may include light diffusers. For example, a light diffuser may be used to diffuse light emitted from a light source. 
     If care is not taken, components for optical systems in an electronic device such as light diffusers may be subject to manufacturing defects such as bubbles, broken seals, or undesirable tolerances. It would therefore be desirable to be able to provide improved optical systems with light diffusers for electronic devices. 
     SUMMARY 
     An electronic device may be provided with a display. The display may be overlapped by a display cover layer. An opaque layer may be formed on an inner surface of the display cover layer in an inactive area of the display. An optical component window may be formed from the opening. Optical component windows may also be formed in other portions of an electronic device. 
     The electronic device may include optical components such as infrared imaging systems and other devices that emit and/or detect light. Infrared imaging systems may incorporate diffusers. The diffuser may be switchable to allow the light source to operate in a flood illumination mode and a structured light mode. The diffuser may include liquid crystal material between first and second substrates. A sealant may surround the liquid crystal layer, and one or more spacer walls may be located between the sealant and the liquid crystal layer. An additional spacer wall may be used outside of the sealant to prevent metal from creating an electrical short between electrodes in the diffuser. Conductive material in the sealant may be used to couple a top electrode to a metal pad on a bottom substrate. 
    
    
     
       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 perspective view of an illustrative electronic device with a display having optical component windows overlapping optical components such as an ambient light sensor in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative electronic device that has optical components such as a light source and an image sensor in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of an illustrative light source that includes a diffuser in accordance with an embodiment. 
         FIG. 5  is a front view of an illustrative object on which a dot pattern is projected using a light source of the type shown in  FIG. 4  in accordance with an embodiment. 
         FIG. 6  is a front view of an illustrative object which is fully illuminated using a light source of the type shown in  FIG. 4  in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of an illustrative diffuser having liquid crystal material surrounded by a sealant and column spacer walls in accordance with an embodiment. 
         FIG. 8  is a top view of an illustrative sealant and column spacer wall arrangement in which an outer spacer wall has no openings and an inner spacer wall has two openings in accordance with an embodiment. 
         FIG. 9  is a top view of an illustrative sealant and column spacer wall arrangement in which an outer spacer wall has no openings and an inner spacer wall has four openings in accordance with an embodiment. 
         FIG. 10  is a top view of an illustrative sealant and column spacer wall arrangement in which an outer spacer wall and an inner spacer wall each have two openings in accordance with an embodiment. 
         FIG. 11  is a bottom view of an illustrative top substrate in a diffuser in accordance with an embodiment. 
         FIG. 12  is a top view of an illustrative bottom substrate in a diffuser in accordance with an embodiment. 
         FIG. 13  is a cross-sectional side view of the diffuser of  FIG. 12  in the vicinity of a metal pad that couples to a signal voltage electrode in accordance with an embodiment. 
         FIG. 14  is a cross-sectional side view of the diffuser of  FIG. 12  in the vicinity of a metal pad that couples to a common voltage electrode in accordance with an embodiment. 
         FIG. 15  is a cross-sectional side view of an illustrative diffuser having a spacer structure that prevents metal from creating an electrical short between a common voltage electrode and a signal voltage electrode in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A schematic diagram of an illustrative electronic device of the type that may be provided with an optical component such as a diffuser 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. 
     As shown in  FIG. 1 , electronic device  10  may have control circuitry  16 . Control circuitry  16  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  16  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. 
     Device  10  may have input-output circuitry such as input-output devices  12 . Input-output devices  12  may include user input devices that gather user input and output components that provide a user with output. Devices  12  may also include communications circuitry that receives data for device  10  and that supplies data from device  10  to external devices. Devices  12  may also include sensors that gather information from the environment. 
     Input-output devices  12  may include one or more displays such as display  14 . Display  14  may be a touch screen display that includes a touch sensor for gathering touch input from a user or display  14  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. Display  14  may be a liquid crystal display, a light-emitting diode display (e.g., an organic light-emitting diode display), an electrophoretic display, or other display. 
     Input-output devices  12  may include optical components  18 . Optical components  18  may include light-emitting diodes and other light sources. As an example, optical components  18  may include one or more visible light sources such as light source  20  (e.g., a light-emitting diode). Light-emitting diode  20  may provide constant illumination (e.g., to implement a flashlight function for device  10 ) and/or may emit pulses of flash illumination for a visible light camera such as visible light image sensor  26 . Optical components  18  may also include an infrared light source (e.g., a laser, lamp, infrared light-emitting diode, an array of vertical-cavity surface-emitting lasers (VCSELs), etc.) such as infrared light source  22 . Infrared light source  22  may provide constant and/or pulsed illumination at an infrared wavelength such as 940 nm, a wavelength in the range of 800-1100 nm, etc. For example, infrared light source  22  may provide constant illumination for an infrared camera such as infrared image sensor  28 . Infrared image sensor  28  may, as an example, be configured to capture iris scan information from the eyes of a user and/or may be used to capture images for a facial recognition process implemented on control circuitry  16 . 
     If desired, infrared light source  22  may be used to provide flood illumination (e.g., diffused infrared light that uniformly covers a given area) and to provide structured light (e.g. a pattern of collimated dots). Flood illumination may be used to capture infrared images of external objects (e.g., to detect a user&#39;s face and/or to create a depth map), whereas structured light may be projected onto an external object to perform depth mapping operations (e.g., to obtain a three-dimensional map of the user&#39;s face). 
     To enable light source  22  to provide both flood illumination and structured light, light source  22  may include a switchable diffuser and a collimated light source such as a laser or an array of vertical cavity surface-emitting lasers. When flood illumination is desired, the diffuser may be turned on to diffuse the light from the light source. When structured illumination is desired, the diffuser may be turned off to allow the collimated light to pass through the diffuser uninhibited. Diffusers such as the diffuser in light source  22  may be formed from liquid crystal material, electrophoretic material, or other switchable light modulators. In some implementations, light source  22  projects light through a diffractive optical element (DOE) to create replicas of the pattern of dots. 
     Optical components  18  may also include optical proximity detector  24  and ambient light sensor  30 . 
     Optical proximity detector  24  may include an infrared light source such as an infrared light-emitting diode and a corresponding light detector such as an infrared photodetector for detecting when an external object that is illuminated by infrared light from the light-emitting diode is in the vicinity of device  10 . 
     Ambient light sensor  30  may be a monochrome ambient light sensor that measures the intensity of ambient light or may be a color ambient light sensor that measures ambient light color and intensity by making light measurements with multiple photodetectors each of which is provided with a corresponding color filter (e.g., color filter that passes red light, blue light, yellow light, green light, or light of other colors) and each of which therefore responds to ambient light in a different wavelength band. 
     In addition to optical components  18 , input-output devices  12  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, light-emitting diodes and other status indicators, non-optical sensors (e.g., temperature sensors, microphones, capacitive touch sensors, force sensors, gas sensors, pressure sensors, sensors that monitor device orientation and motion such as inertial measurement units formed from accelerometers, compasses, and/or gyroscopes), data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices  12  and may receive status information and other output from device  10  using the output resources of input-output devices  12 . 
     Device  10  may have a housing. The housing may form a laptop computer enclosure, an enclosure for a wristwatch, a cellular telephone enclosure, a tablet computer enclosure, or other suitable device enclosure. A perspective view of a portion of an illustrative electronic device is shown in  FIG. 2 . In the example of  FIG. 2 , device  10  includes a display such as display  14  mounted in housing  32 . Housing  32 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  32  may be formed using a unibody configuration in which some or all of housing  32  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). Housing  32  may have any suitable shape. In the example of  FIG. 2 , housing  32  has a rectangular outline (footprint when viewed from above) and has four peripheral edges (e.g., opposing upper and lower edges and opposing left and right edges). Sidewalk may run along the periphery of housing  32 . 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass, clear plastic, sapphire, or other clear layer (e.g., a transparent planar member that forms some or all of a front face of device  10  or that is mounted in other portions of device  10 ). 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, a speaker port such as speaker port  34 , or other components. Openings may be formed in housing  32  to form communications ports (e.g., an audio jack port, a digital data port, etc.), to form openings for buttons, etc. In some configurations, housing  32  may have a rear housing wall formed from a planar glass member or other transparent layer (e.g., a planar member formed on a rear face of device  10  opposing a front face of device  10  that includes a display cover layer). 
     Display  14  may have an array of pixels  38  in active area AA (e.g., liquid crystal display pixels, organic light-emitting diode pixels, electrophoretic display pixels, etc.). Pixels  38  of active area AA may display images for a user of device  10 . Active area AA may be rectangular, may have notches along one or more of its edges, may be circular, may be oval, may be rectangular with rounded corners, and/or may have other suitable shapes. 
     Inactive portions of display  14  such as inactive border area IA may be formed along one or more edges of active area. AA. Inactive border area IA may overlap circuits, signal lines, and other structures that do not emit light for forming images. To hide inactive circuitry and other components in border area IA from view by a user of device  10 , the underside of the outermost layer of display  14  (e.g., the display cover layer or other display layer) may be coated with an opaque masking material such as a layer of black ink (e.g., polymer containing black dye and/or black pigment, opaque materials of other colors, etc.) and/or other layers (e.g., metal, dielectric, semiconductor, etc.). Opaque masking materials such as these may also be formed on an inner surface of a planar rear housing wall formed from glass, ceramic, polymer, crystalline transparent materials such as sapphire, or other transparent material. 
     In the example of  FIG. 2 , speaker port  34  is formed from an elongated opening (e.g., a strip-shaped opening) that extends along a dimension parallel to the upper peripheral edge of housing  32 . A speaker may be mounted within device housing  32  in alignment with the opening for speaker port  34 . During operation of device  10 , speaker port  34  serves as an ear speaker port for a user of device  10  (e.g., a user may place opening  34  adjacent to the user&#39;s ear during telephone calls). 
     Optical components  18  (e.g., a visible digital image sensor, an infrared digital image sensor, a light-based proximity sensor, an ambient light sensor, visible and/or infrared light-emitting diodes that provide constant and/or pulsed illumination, etc.) may be mounted under one or more optical component windows such as optical component windows  40 . In the example of  FIG. 2 , four of windows  40  have circular outlines (e.g., circular footprints when viewed from above) and one of windows  40  has an elongated strip-shaped opening (e.g., an elongated strip-shaped footprint when viewed from above). The elongated window  40  is mounted between the sidewall along the upper peripheral edge of device  10  and speaker port  34  and extends parallel to the upper peripheral edge of housing  32 . If desired, windows such as optical windows  40  may have shapes other than circular and rectangular shapes. The examples of  FIG. 2  are merely illustrative. 
     Optical component windows such as windows  40  may be formed in inactive area IA of display  14  (e.g., an inactive border area in a display cover layer such as an inactive display region extending along the upper peripheral edge of housing  32 ) or may be formed in other portions of device  10  such as portions of a rear housing wall formed from a transparent member coated with opaque masking material, portions of a metal housing wall, polymer wall structures, etc. In the example of  FIG. 2 , windows  40  are formed adjacent to the upper peripheral edge of housing  32  between speaker port opening  34  in the display cover layer for display  14  and the sidewall along the upper edge of housing  32 . In some configurations, an opaque masking layer is formed on the underside of the display cover layer in inactive area IA and optical windows  40  are formed from openings within the opaque masking layer. To help optical windows  40  visually blend with the opaque masking layer, a dark ink layer, a metal layer, a thin-film interference filter formed from a stack of dielectric layers, and/or other structures may be overlap windows  40 . 
     In some modes of operation, device  10  may emit infrared light. Consider, as an example, a scenario in which control circuitry  16  of device  10  is using infrared image sensor  28  to capture eye scan information, facial images (e.g., images of a user&#39;s face for use in performing face recognition operations to authenticate the user of device  10 ), and/or three-dimensional depth mapping information. As shown in  FIG. 3 , device  10  may use infrared light source  22  (e.g., an infrared light-emitting diode, an infrared laser, etc.) to produce infrared light  48 . Light  48  may illuminate external objects in the vicinity of device  10  such as external object  44  (e.g., a user&#39;s face and/or eyes). Reflected infrared light  46  from external object  44  may be received and imaged using infrared digital image sensor  28  to produce infrared images of the face and/or eyes. 
     Infrared light source  22  may operate in different modes depending on the type of infrared information to be gathered by infrared camera  28 . For example, in flood illumination mode, light source  22  may emit diffused light that uniformly covers a desired target area. In a structured light mode, light source  22  may emit a known pattern of light onto a desired target area. 
       FIG. 4  illustrates illumination from light source  22  when light source  22  is operated in a flood illumination mode. As shown in  FIG. 4 , light source  22  may emit diffused infrared light  56  that continuously covers a given area of external object  44 . Infrared camera  28  may capture an infrared image of the diffusely illuminated external object  44 . In some arrangements, flood illumination from light source  22  may be used to detect a user&#39;s face during face identification operations. 
       FIG. 5  illustrates illumination from light source  22  when light source  22  is operated in a structured light mode. In structured light mode, light source  22  may project a known pattern of infrared light  56  onto external object  44 . In the example of  FIG. 5 , infrared light  56  forms a pattern of dots on external object  44 . The dots may be in an ordered grid array (e.g., uniformly spaced from one another), or the dots may be projected in a random speckle pattern. This is, however, merely illustrative. If desired, light source  22  may emit structured light in other patterns (e.g., horizontal lines, vertical lines, a grid of horizontal and vertical lines, or other suitable predetermined pattern). Structured infrared light  44  of  FIG. 5  may be based on laser interference or may be based on a projection display element that emits infrared light through a spatial light modulator to create the desired pattern. 
     In some arrangements, light source  22  may include one light source that provides flood illumination and another light source that provides structured light. In other arrangements, the same light source may be used to provide both flood illumination and structured light. This may be achieved using a switchable diffuser element that selectively diffuses light emitted from the light source. This type of arrangement is shown in  FIG. 6 . 
     As shown in  FIG. 6 , light source  22  may include light-emitting element  50  and switchable diffuser  52 . Light-emitting element  50  may be a laser or other light source that emits collimated infrared light  48  through switchable diffuser  52  towards external object  44 . Diffuser  52  may be formed from a switchable element that is configured to selectively alter the collimated light from light-emitting element  50 . Switchable diffuser  52  may be operable in at least first and second states. In the first state, diffuser  52  may scatter the collimated light from source  50  to produce diffused flood illumination of the type shown in  FIG. 4 . In the second state, diffuser  52  may pass the collimated light from source  50  without altering the light. This allows light  48  to reach object  44  as structured light as shown in the example of  FIG. 5 . Switchable diffuser  52  may be configured in an on state (to diffuse light  48  during flood illumination mode), an off state (to pass light  48  unaltered during a structured light mode), or optionally one or more intermediate states between the on and off states. In some implementations, light source  22  includes projection optics and a diffractive optical element. 
       FIG. 7  is a cross-sectional side view of an illustrative diffuser for light source  22 . As shown in  FIG. 7 , diffuser  52  may include liquid crystal material  64  (e.g., polymer network liquid crystal, polymer dispersed liquid crystal, polymer-stabilized liquid crystal, nematic liquid crystal, or other suitable liquid crystal) between transparent substrates  58  and  60 . Substrates  58  and  60  may be formed from glass, sapphire, plastic, or other transparent substrate material. Electrodes such as electrodes  66  and  68  may be formed on the inner surfaces of substrates  60  and  58 , respectively, and may be used to control the state of liquid crystal material  64 . Electrodes  66  and  68  may be implemented using a transparent conductive material such as indium tin oxide, indium zinc oxide, other transparent conductive oxide material, and/or a layer of metal that is sufficiently thin to be transparent. In some arrangements, electrode  66  may be a common electrode that receives a common electrode voltage (sometimes referred to as Vcom) and electrode  68  may be a signal electrode that receives a signal electrode voltage (sometimes referred to as Vp). 
     During operation, electrode structures  66  and  68  may be used to apply a controlled electric field (i.e., a field having a magnitude proportional to Vp-Vcom) across liquid crystal material  64  in diffuser  52 . The electric field that is produced across liquid crystal material  64  causes a change in the orientation of the liquid crystals in liquid crystal material  64 . This change in orientation of the liquid crystals may be used to control the amount of scattering that light  48  experiences as it passes through diffuser  52 . For example, when an electric field is applied (e.g., when light source  22  is operated in flood illumination mode), light  48  may be scattered in liquid crystal layer  64  to produce diffused light of the type shown in  FIG. 4 . When no electric field is applied (e.g., when light source  22  is operated in a structured light mode), light  48  may pass through diffuser  52  unaltered to produce structured light of the type shown in  FIG. 5 . 
     A sealant such as light-curable and/or thermal-curable sealant  62  may be used to attach substrate  60  to substrate  58 . Sealant  62  may form a peripheral border that surrounds liquid crystal material  64  and that prevents leakage of liquid crystal material  64  at the edges of diffuser  52 . Sealing adhesive  62  may be a light-curable adhesive such as ultraviolet epoxy or other ultraviolet-light-curable material. 
     In some arrangements, diffuser  52  may be formed using a liquid crystal dropping method (sometimes referred to as one-drop filling). In this type of arrangement, a line of sealant  62  is dispensed onto a substrate (either substrate  58  or substrate  60 ). The line of sealant may form a continuous perimeter (e.g., a continuous rectangle or loop) around a central area or the line of sealant may have one or more gaps. The line of sealant may have a rectangular shape, a circular shape, an oval shape, or other suitable shape. Liquid crystal material  64  is dropped onto the substrate within the line of sealant  62 , and then substrates  58  and  60  are assembled to one another under a vacuum. 
     If care is not taken, liquid crystal material may compromise the surrounding sealant during vacuum assembly operations. For example, as the substrates are pressed together, liquid crystal may spread outwardly towards the sealant, which in turn can lead to breaks in the sealant, overflow of the liquid crystal beyond the sealant, contamination of the liquid crystal by contacting the sealant, or bubbles in the liquid crystal. 
     To avoid these issues, one or more spacer walls may be used to separate the liquid crystal from the surrounding sealant. As shown in  FIG. 7 , for example, spacer structure  65  may be interposed between liquid crystal  64  and sealant  62 . Spacer structures such as spacer structure  65  may be formed from photoresist (e.g., acrylic), other polymers, or non-polymer materials. Photolithographic techniques may be used to pattern spacers on layers such as substrate  60  and/or substrate  58 . In the example of  FIG. 7 , spacer structure  65  includes outer spacer wall  65 - 1  and inner spacer wall  65 - 2 . Spacer walls  65 - 1  and  65 - 2  may form continuous perimeters around liquid crystal material  64  or spacers walls  65 - 1  and  65 - 1  may have one or more gaps or openings. 
     As shown in  FIG. 7 , outer spacer wall  65 - 1  may contact sealant  62 . The contact between spacer wall  65 - 1  and sealant  62  helps avoid an enclosed space from forming between sealant  62  and spacer  65 - 1  which would tend to attract liquid crystal  64  during vacuum assembly operations. To avoid a similar issue between outer spacer wall  65 - 1  and inner spacer wall  65 - 2 , inner spacer wall  65 - 2  may have one or more gaps. Inner spacer wall  65 - 2  may be used to slow down liquid crystal material  64  as is spreads outwardly during vacuum assembly operations. 
     Outer spacer wall  65 - 1  may also be used to control the spreading of sealant  62 . In arrangements where sealant  62  is left uncured until after vacuum assembly operations, sealant  62  may be prone to spreading when substrates  58  and  60  are assembled. Inhibiting the spread of sealant  62  may be helpful in maintaining a desired volume within diffuser  52  for liquid crystal material  64 . A predictable cell volume within sealant  62  may in turn allow for more accurate calculations of the amount of liquid crystal  64  needed during one-drop-fill operations. 
     The example of  FIG. 7  in which outer spacer wall  65 - 1  contacts sealant  62  is merely illustrative. If desired, a gap may be present between outer spacer wall  65 - 1  and sealant  62 . 
     Illustrative examples of spacer wall patterns that may be used for spacer structure  65  in diffuser  52  are shown in  FIGS. 8, 9, and 10 . 
     In the example of  FIG. 8 , outer spacer wall  65 - 1  forms a continuous rectangular loop without gaps, whereas inner spacer wall  65 - 2  forms a rectangular loop with an opening  70  in each of two opposing sides of the rectangular loop. If desired, there may be greater or fewer than two openings  70  in inner spacer wall  65 - 2 . The example of  FIG. 8  is merely illustrative. 
     In the example of  FIG. 9 , outer spacer wall  65 - 1  forms a continuous rectangular loop without gaps, whereas inner spacer wall  65 - 2  forms a rectangular loop with an opening  70  in each of the four sides of the rectangular loop. If desired, there may be greater or fewer than four openings  70  in inner spacer wall  65 - 2 . The example of  FIG. 9  is merely illustrative. 
     In the example of  FIG. 10 , both outer spacer wall  65 - 1  and inner spacer wall  65 - 2  form rectangular loops with gaps. Inner spacer wall  65 - 2  has openings  70  in each of two opposing sides of the rectangular loop, and outer spacer wall  65 - 1  has openings  72  in each of two opposing sides of the rectangular loop. As shown in  FIG. 10 , openings  70  and  72  may be offset from one another to avoid a direct path for liquid crystal  64  ( FIG. 7 ) to reach sealant  62 . If desired, there may be greater or fewer than two openings in each spacer wall. The example of  FIG. 10  is merely illustrative. 
     The examples of  FIGS. 8, 9, and 10  in which sealant  62  and spacer walls  65 - 1  and  65 - 2  form rectangular perimeters (e.g., rectangular loops) around the liquid crystal material are merely illustrative. If desired, sealant  62  and spacer walls  65 - 1  and  65 - 2  may have other shapes (e.g., oval, circular, or other suitable shape). 
     Similarly, the examples of  FIGS. 8, 9, and 10  that show vertical openings in spacer structure  65  (e.g., vertical openings that extend between upper substrate  60  and lower substrate  58 ) are merely illustrative. If desired, openings  70  and/or openings  72  may be horizontal openings that extend between liquid crystal layer  64  and sealant  62 . Horizontal openings may be a series of slits, gaps, or holes of any suitable shape (rectangular, circular, etc.). Horizontal openings may extend only across short segments of spacer structure  65  or may extend continuously around some or all of the perimeter of spacer structure  65 . In general, openings in spacer structure  65  may have any suitable shape, size, number, or orientation. 
     Electrodes  66  and  68  of diffuser  52  may be coupled to metal pads. In some arrangements, both metal pads may be formed on the same substrate. For example, a first metal pad coupled to signal electrode  68  may be formed on lower substrate  58  and a second metal pad coupled to common voltage electrode  66  may also be formed on lower substrate  58 . Since common electrode  66  is located on top substrate  60 , conductive structures may be used to couple common electrode  66  on top substrate  60  to the metal pad on bottom substrate  58 . This type of arrangement is illustrated in  FIGS. 11-15 . 
       FIG. 11  shows a bottom view of upper substrate  60 . As shown in  FIG. 11 , top common voltage electrode  66 T may be formed from a blanket layer of transparent conductive oxide such as indium tin oxide on substrate  60 . Top common voltage electrode  66 T may cover the active area of diffuser  52 . 
       FIG. 12  shows a top view of lower substrate  58 . As shown in  FIG. 12 , signal voltage electrode  68  may be formed on lower substrate  58 , but may cover a smaller portion of the active area of diffuser  52  than top common voltage electrode  66 T. Metal pads such as metal pads  74  and  76  may be used to couple electrodes  66  and  68  to control circuitry in device  10 . Signal voltage electrode  68  may be coupled to metal pad  74 , and common voltage electrode  66  may be coupled to metal pad  76 . To couple top common voltage electrode  66 T on upper substrate  60  to metal pad  76  on lower substrate  58 , diffuser  52  may include a conductive structure in sealant  62 . A top portion of the conductive structure may be coupled to top common voltage electrode layer  66 T, and a lower portion of the conductive structure may be coupled to a bottom common voltage electrode layer  66 B. As shown in  FIG. 12 , bottom common voltage electrode  66 B is formed on lower substrate  58  and is formed adjacent to signal voltage electrode  68  without contacting signal voltage electrode  68 . Connections between top common voltage electrode  66 T and bottom common voltage electrode  66 B may be formed at one or more locations such as locations  90 . 
     Because sealant  62  includes conductive structures, care must be taken to ensure that the conductive structures in sealant  62  do not create an electrical short between signal voltage electrode  68  and common voltage electrode  66 . To insulate sealant  62  from signal voltage electrode  68 , diffuser  52  may include an insulating layer that covers signal voltage electrode  68 . The passivation layer may include openings in locations  90  to allow conductive structures in sealant  62  to electrically couple top common voltage electrode  66 T to bottom common voltage electrode  66 B. 
       FIG. 13  is a cross-sectional side view of diffuser  52  of  FIG. 12  taken along line  78  and viewed in direction  80 . As shown in  FIG. 13 , a conductive structure such as conductive structure  86  may be formed within sealant  62 . Conductive structure  86  may be a bead of conductive material such as metal (e.g., gold, silver, or other suitable metal). The top portion of conductive structure  86  may be electrically coupled to top common voltage electrode  66 T. To prevent the lower portion of conductive structure  86  from creating an electrical short between top common voltage electrode  66 T and signal voltage electrode  68 , insulating layer  88  may be formed over signal voltage electrode  68  (e.g., between sealant  62  and signal voltage electrode  68 ). Insulating layer  88  may be an oxide passivation layer, may be a polymer-based insulating layer, or may be formed from other insulating materials (e.g., organic and/or inorganic insulating materials). 
       FIG. 14  is a cross-sectional side view of diffuser  52  of  FIG. 12  taken along line  82  and viewed in direction  84 . As shown in  FIG. 14 , openings such as openings  90  may be formed in passivation layer  88  to allow conductive structure  86  to make contact with bottom common voltage electrode  66 B. If desired, openings may be forming at multiple locations of passivation layer  88  (e.g., locations  90  of  FIG. 12  and/or other suitable locations of passivation layer  88 ). This allows top common voltage electrode  66 T to electrically couple to metal pad  76  through conductive structure  86  and bottom common voltage electrode  66 B. 
     In some arrangements, metal may be used to enhance the electrical and mechanical connection to metal pads  74  and  76 . Care must be taken, however, to ensure that the metal does not create an electrical short between top common voltage electrode  66 T and signal voltage electrode  68 . If desired, spacer structures may be used on the outside of sealant  62  to prevent metal from creating an electrical short between top common voltage electrode  66 T and the signal voltage electrode  68 . This type of arrangement is illustrated in  FIG. 15 . 
       FIG. 15  is a cross-sectional side view of diffuser  52  showing how one or more additional spacer structures may be used on the outside of sealant  62  to prevent an electrical short from forming between electrode layers. 
     Diffuser  52  includes conductive structures such as metal bead  92  (e.g., a bead of silver, gold, or other suitable metal) to enhance the connection between the transparent conductive oxide that forms electrode  68  and metal pad  74 . To prevent metal bead  92  from creating an electrical short between signal voltage electrode  68  and top common voltage electrode  66 T, diffuser  52  may include a spacer structure such as insulating spacer structure  94 . Spacer structure  94  may be formed from a photodefinable polymer or other suitable insulating material. If desired, spacer structure  94  may be formed from the same patterned layer of photodefinable polymer that forms spacer structures  65 . Spacer structure  94  may completely surround sealant  62  or may be formed selectively around portions of sealant  62 . For example, spacer structure  94  need not be formed in the vicinity of pad  76  ( FIG. 12 ) because it is not necessary to prevent metal bead  92  from contacting top common voltage electrode  66 T and bottom common voltage electrode  66 B, since these two electrodes are already coupled to one another using conductive structure  86 . In the example of  FIG. 15 , there are multiple conductive beads  86  within sealant  62  to couple top common electrode  66 T to bottom common electrode  66 B. 
     The presence of spacer structure  94  and outer spacer wall  65 - 1  may help control the width of sealant  62 . When substrates  58  and  60  are attached in vacuum assembly operations, wall  65 - 1  and structure  94  may inhibit the spread of sealant  62  so that a desired cell volume for liquid crystal  62  can be maintained. A predictable cell volume within sealant  62  may in turn allow for more accurate calculations of the amount of liquid crystal  64  needed during one-drop-fill operations. 
     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: 20180925
Publication Date: 20210831
Grant Date: 20210831
Priority Date: 20171106
Inventors: LIM, Junhwan
GE, ZHIBING
BOITNOTT, CHRISTOPHER L.
CHANG, SHIH-WEI
CHOI, SANG UN
JINASUNDERA, SUDIRUKKUGE T.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/1339", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13756", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13394", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13318", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2203/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F2203/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/4204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133388", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13318", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1334", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13394", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1334", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13756", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/0474", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/041", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133388", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1339", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0304", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1339", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2203/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0304", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133388", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01J1/4204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13318", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1334", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/041", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/0474", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13756", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13394", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 66326951