PATENT DOCUMENT

Publication Number: US-9435937-B2
Application Number: US-201414332111-A
Country: US
Kind Code: B2

Title: System for assembling optical films for displays

Abstract:
Display backlight structures may provide backlight illumination that passes through display layers in the display. Computer-controlled equipment such as robotic arms with gripper structures may be used in assembling backlight layers such as a reflector, light guide plate, diffusers, and prism films into a backlight unit. The grippers may include mechanical grippers and vacuum heads. A vacuum gripper head may have a plenum to which a perforated plate and porous layer are attached for distributing the vacuum. Computer-controlled air sources may be used to blow streams of deionized air between backlight layers to separate the backlight layers during assembly. Release liners may be removed using robotic arms and grippers. Translation stages may move a backlight layer storage frame between stations. A cleaning tool with a solvent dispenser and air jets may clean backlight layers. A camera system may be used during alignment and positioning operations.

Claims:
What is claimed is: 
     
       1. A system for assembling a display backlight unit, comprising:
 a robotic arm; 
 a gripper mounted on the robotic arm; 
 a controller that directs the robotic arm and the gripper to assemble display backlight layers to form the backlight unit; 
 deionized air sources controlled by the controller; and 
 a backlight layer storage frame, wherein the deionized air sources blow streams of air across the backlight layer storage frame to separate the backlight layers. 
 
     
     
       2. The system defined in  claim 1  wherein the gripper comprises a vacuum gripper. 
     
     
       3. The system defined in  claim 2  wherein the vacuum gripper comprises:
 a layer of porous material; 
 a plenum that receives vacuum; and 
 a perforated plate interposed between the plenum and the layer of porous material. 
 
     
     
       4. The system defined in  claim 3  wherein the perforated plate has rows and columns of perforations. 
     
     
       5. The system defined in  claim 4  further comprising:
 a camera system, wherein the controller controls the robotic arm based on information from the camera system. 
 
     
     
       6. The system defined in  claim 1  wherein the deionized air sources comprise at least one pressurized air nozzle that blows a puff of air between the backlight layers to separate the backlight layers. 
     
     
       7. The system defined in  claim 1  further comprising:
 a source of the backlight layers, 
 wherein the backlight layer storage frame is configured to receive the backlight layers, and wherein the controller is configured to direct the robotic arm and the gripper to move the backlight layers from the source of backlight layers into the backlight layer storage frame. 
 
     
     
       8. The system defined in  claim 7  further comprising a translation stage that laterally moves the backlight layer storage frame. 
     
     
       9. The system defined in  claim 8  wherein further comprising a cleaning tool that includes a solvent dispenser that dispenses solvent onto the backlight layers and a nozzle that blows air to remove the solvent from the backlight layers. 
     
     
       10. The system defined in  claim 9  further comprising a computer-controlled release liner removal tool that peels release liner layers from the backlight layers. 
     
     
       11. The system defined in  claim 2 , wherein the backlight layers are stored in an opening in the backlight layer storage frame, and wherein the deionized air sources blow streams of air across the backlight layer storage frame between first and second backlight layers in order to separate the first and second backlight layers while the vacuum gripper pulls the first backlight layer away from the second backlight layer. 
     
     
       12. A system for assembling a display backlight unit, comprising:
 a source of backlight layers; 
 computer-controlled equipment that assembles the backlight layers from the source to form the backlight unit, wherein the computer-controlled equipment includes at least one robotic arm; 
 a controller that controls the equipment, wherein the controller directs the at least one robotic arm to separate a first backlight layer of the backlight layers from a second backlight layer of the backlight layers; and 
 deionized air sources controlled by the controller that blow streams of deionized air between the first and second backlight layers while the at least one robotic arm separates the first and second backlight layers. 
 
     
     
       13. The system defined in  claim 12  wherein the computer-controlled equipment includes a vacuum gripper mounted to the at least one robotic arm that holds the backlight layers during movement of the robotic arm and wherein the backlight layers comprise layers selected from the group consisting of: a reflector layer, a light guide plate, a diffuser layer, and a prism film layer. 
     
     
       14. A method of assembling backlight layers to form a backlight unit, comprising:
 using at least one robotic arm to move backlight layers from a source of the backlight layers into a central opening of a temporary storage frame, wherein the backlight layers comprise layers selected from the group consisting of: a reflector layer, a light guide plate, a diffuser layer, and a prism film layer; 
 separating the backlight layers from each other by blowing air between the backlight layers with a computer-controlled air source; and 
 using the at least one robotic arm to place the backlight layers in a support structure. 
 
     
     
       15. The method defined in  claim 14  wherein using the at least one robotic arm comprises:
 with a vacuum head attached to the at least one robotic arm, holding the backlight layers. 
 
     
     
       16. The method defined in  claim 15  further comprising:
 removing release liners from the backlight layers using a computer-controlled gripper. 
 
     
     
       17. The method defined in  claim 14 , wherein the temporary storage frame has a base and a plurality of vertically extending guide fingers, wherein the plurality of vertically extending guide fingers define the central opening, and wherein the central opening is a central rectangular opening. 
     
     
       18. The method defined in  claim 17 , wherein the support structure comprises a backlight unit chassis. 
     
     
       19. The method defined in  claim 14 , wherein separating the backlight layers from each other comprises separating a first backlight layer from a second backlight layer, and wherein separating the first backlight layer from the second backlight layer comprises using the at least one robotic arm to separate the first backlight layer from the second backlight layer while the computer-controlled air source blows air between the first and second backlight layers.

Description:
BACKGROUND 
     This relates generally to electronic devices, and more particularly, to electronic devices with displays. 
     Electronic devices often include displays. For example, cellular telephones and portable computers may have displays for presenting information to a user. 
     Displays typically include multiple layers of material. For example, a liquid crystal display may have a color filter layer, liquid crystal layer, and thin-film transistor layer sandwiched between upper and lower polarizers. 
     Backlight units may be used to supply backlight illumination to a display such as a liquid crystal display or other display. A backlight unit may include layers such as a reflector, a light guide plate, diffusers, and prism films. These backlight layers may be challenging to assemble with desired levels of alignment accuracy, assembly speed, and cleanliness. 
     It would therefore be desirable to be able to provide improved systems for assembling display layers such as display backlight layers. 
     SUMMARY 
     A backlight unit may provide backlight illumination that passes through display layers in a display. The display may be a liquid crystal display or other display. The backlight unit may be formed from backlight layers such as reflector, light guide plate, diffusers, and prism films. The backlight layers may be mounted in an electronic device housing, a backlight chassis, or other support structures. 
     Computer-controlled equipment such as robotic arms with gripper structures may be used in assembling backlight layers into a backlight unit. Grippers on the robotic arms may include mechanical grippers and vacuum heads. 
     A vacuum head may have a plenum to which a perforated plate and porous layer are attached for evenly distributing vacuum suction. When a vacuum is applied to the vacuum head, the vacuum head may hold a backlight layer at the end of a robotic arm. 
     Computer-controlled air sources may be used to blow streams of deionized air between backlight layers to separate the backlight layers during assembly. The air sources may be arranged around the periphery of a set of rectangular backlight layers. 
     Release liners may be removed from the backlight layers using robotic arms and grippers. Translation stages may move a backlight layer storage frame between stations. A cleaning tool with a solvent dispenser and air jets may clean the backlight layers. 
     A camera system may be used during alignment and positioning operations. A controller may control operation of the robotic arms, grippers, air sources and other computer-controlled equipment based in information from the camera system and other information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a laptop computer with a display in accordance with an embodiment. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a handheld electronic device with a display in accordance with an embodiment. 
         FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer with a display in accordance with an embodiment. 
         FIG. 4  is a perspective view of an illustrative electronic device such as a computer display with display structures in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of an illustrative display in accordance with an embodiment. 
         FIG. 6  is a system diagram of illustrative equipment of the type that may be used in assembling display backlight layers in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of an illustrative display showing backlight layers that may be used in constructing a backlight unit in accordance with an embodiment. 
         FIG. 8  is a perspective view of an illustrative storage frame of the type that may be used to hold backlight layers for a backlight unit in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of an illustrative compressed air nozzle being used to control the separation of adjacent backlight layers by blowing across a storage frame or otherwise blowing between backlight layers during assembly of a backlight unit in accordance with an embodiment. 
         FIGS. 10, 11, and 12  are illustrative air jet strength profiles that may be used by deionized air dispensers when handling backlight layers in accordance with an embodiment. 
         FIG. 13  is a cross-sectional side view of an illustrative backlight layer cleaning tool in accordance with an embodiment. 
         FIG. 14  is a diagram of robotic equipment for manipulating backlight layers during backlight layer assembly in accordance with an embodiment. 
         FIG. 15  is an exploded perspective view of an illustrative vacuum head for use in gripping backlight layers in accordance with an embodiment. 
         FIG. 16  is a cross-sectional side view of the vacuum head of  FIG. 15  in accordance with an embodiment. 
         FIG. 17  is a perspective view of an illustrative camera system for monitoring backlight layers during backlight assembly operations in accordance with an embodiment. 
         FIG. 18  is a cross-sectional side view of an illustrative backlight layer that has upper and lower release liners in accordance with an embodiment. 
         FIG. 19  is a cross-sectional side view of the illustrative backlight layer of  FIG. 18  showing how the release liners can be removed during assembly of a backlight unit in accordance with an embodiment. 
         FIG. 20  is a cross-sectional side view of the backlight layer of  FIGS. 18 and 19  following removal of the release liners in accordance with an embodiment. 
         FIG. 21  is a diagram of illustrative robotic equipment for removing release liners from backlight layers in accordance with an embodiment. 
         FIG. 22  is a cross-sectional side view of an illustrative display backlight unit showing how strips of adhesive may be used in securing display layers within a backlight unit support structure in accordance with an embodiment. 
         FIG. 23  is a cross-sectional side view of a portion of a registration pin in a backlight unit support structure and an associated set of backlight layers with mating registration openings in accordance with an embodiment. 
         FIG. 24  is a flow chart of illustrative steps involved in assembling display layers such as display backlight layers for a backlight unit or other structure in a display in an electronic device in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may include displays. The displays may be used to display images for a user. Illustrative electronic devices that may be provided with displays are shown in  FIGS. 1, 2, 3, and 4 . 
     Illustrative electronic device  10  of  FIG. 1  has the shape of a laptop computer having upper housing  12 A and lower housing  12 B with components such as keyboard  16  and touchpad  18 . Device  10  may have hinge structures  20  that allow upper housing  12 A to rotate in directions  22  about rotational axis  24  relative to lower housing  12 B. Display  14  may be mounted in upper housing  12 A. Upper housing  12 A, which may sometimes be referred to as a display housing or lid, may be placed in a closed position by rotating upper housing  12 A towards lower housing  12 B about rotational axis  24 . 
       FIG. 2  shows how electronic device  10  may be a handheld device such as a cellular telephone, music player, gaming device, navigation unit, or other compact device. In this type of configuration for device  10 , housing  12  may have opposing front and rear surfaces. Display  14  may be mounted on a front face of housing  12 . Display  14  may, if desired, have openings for components such as button  26 . Openings may also be formed in display  14  to accommodate a speaker port (see, e.g., speaker port  28  of  FIG. 2 ). 
       FIG. 3  shows how electronic device  10  may be a tablet computer. In electronic device  10  of  FIG. 3 , housing  12  may have opposing planar front and rear surfaces. Display  14  may be mounted on the front surface of housing  12 . As shown in  FIG. 3 , display  14  may have an opening to accommodate button  26  (as an example). 
       FIG. 4  shows how electronic device  10  may be a computer display, a computer that has been integrated into a computer display, or a display for other electronic equipment. With this type of arrangement, housing  12  for device  10  may be mounted on a support structure such as stand  30  or stand  30  may be omitted (e.g., stand  30  can be omitted when mounting device  10  on a wall). Display  14  may be mounted on a front face of housing  12 . 
     The illustrative configurations for device  10  that are shown in  FIGS. 1, 2, 3, and 4  are merely illustrative. In general, electronic device  10  may be a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     Housing  12  of device  10 , which is sometimes referred to as a case, may be formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials. Device  10  may be formed using a unibody construction in which most or all of housing  12  is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures). 
     Display  14  may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. Touch sensors for display  14  may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components. 
     Display  14  for device  10  may include display pixels formed from liquid crystal display (LCD) components or other suitable image pixel structures. 
     A display cover layer may cover the surface of display  14  or a display layer such as a color filter layer or other portion of a display may be used as the outermost (or nearly outermost) layer in display  14 . The outermost display layer may be formed from a transparent glass sheet, a clear plastic layer, or other transparent member. 
     A cross-sectional side view of an illustrative configuration for display  14  of device  10  (e.g., for display  14  of the devices of  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 4  or other suitable electronic devices) is shown in  FIG. 5 . As shown in  FIG. 5 , display  14  may include backlight structures such as backlight unit  42  for producing backlight  44 . During operation, backlight  44  travels outwards (vertically upwards in dimension Z in the orientation of  FIG. 5 ) and passes through display pixel structures in display layers  46 . This illuminates any images that are being produced by the display pixels for viewing by a user. For example, backlight  44  may illuminate images on display layers  46  that are being viewed by viewer  48  in direction  50 . 
     Display layers  46  may be mounted in chassis structures such as a plastic chassis structure and/or a metal chassis structure to form a display module for mounting in housing  12  or display layers  46  may be mounted directly in housing  12  (e.g., by stacking display layers  46  into a recessed portion in housing  12 ). Display layers  46  may form a liquid crystal display or may be used in forming displays of other types. 
     In a configuration in which display layers  46  are used in forming a liquid crystal display, display layers  46  may include a liquid crystal layer such a liquid crystal layer  52 . Liquid crystal layer  52  may be sandwiched between display layers such as display layers  58  and  56 . Layers  56  and  58  may be interposed between lower polarizer layer  60  and upper polarizer layer  54 . 
     Layers  58  and  56  may be formed from transparent substrate layers such as clear layers of glass or plastic. Layers  56  and  58  may be layers such as a thin-film transistor layer and/or a color filter layer. Conductive traces, color filter elements, transistors, and other circuits and structures may be formed on the substrates of layers  58  and  56  (e.g., to form a thin-film transistor layer and/or a color filter layer). Touch sensor electrodes may also be incorporated into layers such as layers  58  and  56  and/or touch sensor electrodes may be formed on other substrates. 
     With one illustrative configuration, layer  58  may be a thin-film transistor layer that includes an array of thin-film transistors and associated electrodes (display pixel electrodes) for applying electric fields to liquid crystal layer  52  and thereby displaying images on display  14 . Layer  56  may be a color filter layer that includes an array of color filter elements for providing display  14  with the ability to display color images. If desired, lower layer  58  may be a color filter layer and upper layer  56  may be a thin-film transistor layer. Another illustrative configuration involves forming color filter elements and thin-film transistor circuits with associated pixel electrodes on a common substrate. This common substrate may be the upper substrate or may be the lower substrate and may be used in conjunction with an opposing glass or plastic layer (e.g., a layer with or without any color filter elements, thin-film transistors, etc.) to contain liquid crystal layer  52 . 
     During operation of display  14  in device  10 , control circuitry (e.g., one or more integrated circuits on a printed circuit) may be used to generate information to be displayed on display  14  (e.g., display data). The information to be displayed may be conveyed to a display driver integrated circuit such as circuit  62 A or  62 B using a signal path such as a signal path formed from conductive metal traces in a rigid or flexible printed circuit such as printed circuit  64  (as an example). 
     Backlight structures  42  may include a light guide plate such as light guide plate  78 . Light guide plate  78  may be formed from a transparent material such as clear glass or plastic. During operation of backlight structures  42 , a light source such as light source  72  may generate light  74 . Light source  72  may be, for example, an array of light-emitting diodes. If desired, light sources such as light source  72  may be located along multiple edges of light guide plate  78 . 
     Light  74  from light source  72  may be coupled into edge surface  76  of light guide plate  78  and may be distributed in dimensions X and Y throughout light guide plate  78  due to the principal of total internal reflection. Light guide plate  78  may include light-scattering features such as pits or bumps. The light-scattering features may be located on an upper surface and/or on an opposing lower surface of light guide plate  78 . 
     Light  74  that scatters upwards in direction Z from light guide plate  78  may serve as backlight  44  for display  14 . Light  74  that scatters downwards may be reflected back in the upwards direction by a reflective film such as reflector  80 . Reflector  80  may be formed from a reflective material such as a reflective layer of white plastic, a plastic layer formed form a stack of plastic films with alternating high and lost indices of refraction that serve as a high efficiency reflector, or other reflective materials. 
     To enhance backlight performance for backlight structures  42 , backlight structures  42  may include optical films  70 . Optical films  70  may include one or more diffuser layers for helping to homogenize backlight  44  and thereby reduce hotspots and one or more prism films (also sometimes referred to as turning films or brightness enhancement films) for collimating backlight  44 . 
     Compensation films for enhancing off-axis viewing may be included in optical films  70  or may be incorporated into other portions of display  14  (e.g., polarizer layers). Optical films  70  may also include other backlight layers, if desired. 
     Optical films  70  may overlap the other structures in backlight unit  42  such as light guide plate  78  and reflector  80 . For example, if light guide plate  78  has a rectangular footprint in the X-Y plane of  FIG. 5 , optical films  70  and reflector  80  may have matching rectangular footprints. 
       FIG. 6  is a diagram of an illustrative system that may be used for assembling structures for display  14  such as backlight structures  42 . As shown in  FIG. 6 , system  90  includes equipment for processing structures  110  (e.g., backlight layers such as a reflector, light guide plate, diffusers, prism films, etc.). 
     The equipment of system  90  may obtain backlight layers from a source of backlight layers such as film source  112 . Source  112  may contain stacks of backlight layers such as one or more stacks of diffusers, one or more stacks of prism films, one or more stacks of reflectors, and one or more stacks of light guide plates (as examples). Each stack may contain a single type of backlight layer (or other display layer) or, if desired, stacks of backlight films may be provided that contain layers organized in a predetermined pattern (e.g., a stack containing a number of different types of backlight layers in a predetermined repeating order). The equipment of system  90  may move backlight layers (or other display layers such as polarizers, glass substrates, etc.) from source  112  to storage frame  114 . 
     A housing such as housing  116  or other display backlight unit support structure (e.g., a chassis, etc.) may receive backlight layers from one or more storage frames  114 . After backlight unit  42  has been assembled, display  14  and the other components of device  10  can be assembled to form a finished device  10  (e.g., device  10  of  FIG. 1, 2, 3 , or  4  or other suitable device). 
     Computer-controlled release liner removal tool  92  may be used to remove protective release liner layers from backlight layers. For example, tool  92  may peel release liners off of light guide plates and other layers in backlight unit  42 . Release liners may also be removed from backlight layers manually. 
     Camera system  94  may include on or more cameras that form a machine vision system. Camera images may be viewed by personnel operating the equipment of system  90  in real time. Camera data may also be processed for use in automatically guiding the equipment of system  90  so that backlight units may be assembled autonomously. For example, camera system  94  may be used to gather information on the position of the edges of the backlight layers in backlight unit  42 . System  90  may use information on the location of the edges of the backlight layers in performing alignment operations and other assembly operations. 
     Film cleaning tool  96  may be used to remove dirt and other extraneous particles from the backlight layers of backlight unit  42 . The backlight layers may become statically charged during handling. The use of film cleaning tool  96  may help ensure that any particles that have been attracted to a backlight layer through electrostatic attraction are removed. 
     Controller  98  may be based on a microcontroller, a microprocessor, memory (e.g., volatile memory and/or non-volatile memory) and other storage, application-specific integrated circuits, and/or other circuit resources, one or more networked computers, stand-alone computing equipment, or other control circuitry. Controller  98  may be used in running code that controls the operation of system  90 . 
     One or more computer-controlled tools (sometimes referred to as robots or robotic tools) may be used to manipulate the layers of backlight structures  42 . For example, computer-controlled layer manipulation tools such as a robot  100  may be provided with vacuum gripper equipment to hold backlight layers during processing. 
     The tools of system  90  may be arranged in one or more stations. To move backlight layers and other structures between stations (e.g., to move storage frames, housings, etc.), one or more translation stages may be provided in system  90  such as translation stage  102 . Stages  102  may include trays, storage frames, or other structures that run along rails between stages, may include conveyor belts, or may include other equipment for moving backlight structures and other device structures between different locations in system  90 . 
     Backlight layers may be formed from materials such as polymers that tend to adhere to each other through due to electrostatic attraction. Computer-controlled air sources such as deionized air sources  108  may be used to help separate backlight layers from each other and may be used to maintain separated layers in their separated state. 
     A housing, chassis, or other support structure may be provided with alignment features such as one or more registration pins. The layers of material in backlight unit  42  may be provided with corresponding openings that mate with the registration pins, thereby aligning the layers of material with respect to each other. Adhesive application tool  106  may be used to attach adhesive tape over the exposed tips of the registration pins to retain the backlight layers within backlight unit  42  following assembly. If desired, tool  106  may include other equipment for securing backlight layers within backlight unit  42  (e.g., using fasteners, adhesive, etc.). 
     In general, system  90  may be used to assembly any suitable structures in device  10  such as one or more display layers, housing structures, etc. Arrangements in which system  90  is used in assembling backlight layers such as reflector layers, light guide plates, diffuser layers, and prism films into backlight unit  42  are sometimes described herein as an example. A cross-sectional side view of an illustrative display that may be assembled using system  90  is shown in  FIG. 7 . In the example of  FIG. 7 , display  14  includes display layers  46  (e.g., a liquid crystal display module) and backlight unit  42 . Backlight unit  42  (sometimes referred to as a backlight or backlight structures) may include multiple backlight layers  118 . Layers  118  may, for example, include reflector  80 , light guide plate  78 , and optical films such as lower diffuser  70 - 1 , prism films  70 - 2  and  70 - 3 , and upper diffuser layer  70 - 4 . Other configurations may be used for backlight unit  42  if desired. The example of  FIG. 7  is merely illustrative. 
     During backlight assembly, system  90  may temporarily retain backlight layers  118  in one or more storage structures such as storage frame  114  of  FIG. 8 . Storage frame  114  may have a base such as base  120  and a series of vertically extending guide fingers such as fingers  122  or other suitable backlight layer guide structures. Fingers  122  may be arranged in a rectangle or other suitable pattern that defines an opening to receive backlight layers  118 . If, for example, backlight layers  118  are rectangular, fingers  122  may be organized to form a central rectangular opening for storage unit (frame)  114 . As shown in  FIG. 8 , rectangular backlight layers  118  may be stored in the rectangular opening defined by fingers  122 . 
     Storage frames such as frame  114  of  FIG. 8  may be used to temporarily hold stacks of backlight layers  118  for transfer between processing stations, to provide a buffer between tools that are operating at different speeds (e.g., to allow one tool to store its output at a rate that is appropriate for that tool without being concerned about the input rate of one or more downstream tools that may consume that output), to hold backlight layers  118  that are being assembled in a particular order (e.g., a particular layer on the bottom, another layer above the bottom layer, and so forth), may be used to hold layers  118  for shipment to a remote facility, or may be otherwise used in temporarily storing layers  118  during processing of layers  118  to form backlight units  42  and displays  14 . 
     Backlight layers  118  may be formed from dielectric materials (e.g., clear and/or translucent polymer layers). These layers are often not sufficiently conductive to readily discharge static electricity. Due to the presence of static charge on layers  118 , layers  118  may have a propensity to adhere to each other. This can pose handling challenges. To help control the separation of layers  118  from each other so that layers  118  can be positioned where desired without becoming stuck due to static charge, deionized air may be blown between adjacent layers  118 . 
       FIG. 9  is a diagram showing how streams of compressed deionized air may be used in controlling the separation of adjacent layers  118 . As shown in  FIG. 9 , pressurized deionized air dispensing system  108  may dispense streams of deionized air  128  between adjacent backlight layers  118  such as adjacent layers  118 A and  118 B. Air  128  may be dispensed in short puffs, may be dispensed in longer sustained bursts, or may be dispensed (blown) with other air flow characteristics. 
     Pressurized deionized air dispensing system  108  may include a source of compressed deionized air such as compressed air source  132 . Air source  132  may contain air, nitrogen, or other gas. One or more computer-controlled values such as valve  130  may control the flow of air from source  132  to air dispensing nozzle  126 . Valve  130  may, for example, be controlled by controller  98  of  FIG. 6  using control signals at control input  158 . 
     Different flow profiles (air flow strength F versus time t) may be used for different applications (e.g., initial layer separation versus maintaining separation of layers that have already been separated, separating different types of layers from each other, separating layers in an initial stack of layers of the same type, separating layers that have been stacked with layers of other types in a storage frame, etc.). Examples of illustrative air flow profiles that may be used with air dispensing system  108  are shown in  FIG. 10 , which shows a single short puff of air,  FIG. 11 , which shows a pair of puffs, and  FIG. 12 , which shows a longer burst of air characterized by a relatively long ramp up time, a relatively long steady sustained flow value, and a relatively long ramp down time. 
     The examples of  FIGS. 10, 11, and 12  are merely illustrative. Other types of air flows may be used by system  108  to handle backlight layers  118  if desired. Moreover, multiple air dispensing nozzles may be used at the same time to handle a stack of backlight layers. As an example, there may be one nozzle, two nozzles (e.g., nozzles on opposing edges of a rectangular stack of backlight layers  118  or at right angles to each other), three nozzles located at three different edges of the backlight layers, or four nozzles each located at a different respective edge in a set of stacked backlight layers  110 . In a multi-nozzle arrangement, each nozzle may dispense a respective stream of air with an identical and synchronized air flow profile or different nozzles may dispense different air flows (e.g., one side of a four nozzle system may deliver an initial puff of air, followed by sustained streams of air from all four sides, etc.). 
     It may be desirable to operate system  90  in a clean room environment to reduce particulates. Backlight layers  118  may also be cleaned using a cleaning tool such as tool  96  of  FIG. 13 . As shown in  FIG. 13 , tool  96  may have a moving surface such as moving upper surface  134  of conveyor belt  136 . Upper surface  134  of belt  136  may be moved in direction  154  by running belt  136  around clockwise-spinning rollers  138 . 
     Initially, a backlight layer such as illustrative backlight layer  118 - 1  may have a surface such as surface  152  on which dirt or other contaminant particles  150  are present. As belt  136  moves layer  118 - 1  through cleaning chamber  140 , particles  150  may be removed, as illustrated by clean upper surface  152  on backlight layer  118 - 2  at the exit of chamber  140 . Cleaning chamber  140  may contain one or more tools for cleaning backlight layers. For example, chamber  140  may include a solvent mister such as mister  142  or other solvent dispenser that dispenses a mist of solvent  144  onto the surface of each backlight layer. Chamber  140  may also contain air nozzles such as nozzle  146  that dispense streams of clean air  148  (e.g., deionized air), thereby blowing away and removing excess solvent from the surface of each backlight layer. There may be any suitable number of solvent dispensing nozzles and any suitable number of pressurized air dispensing nozzles in system  96  (e.g., one solvent dispensing nozzle and one set of air dispensing nozzles, multiple stages of solvent/air nozzles through which the backlight layers pass in succession, etc.). 
       FIG. 14  is a diagram of a camera system and robotic equipment of the type that may be used in system  90  to handle backlight layers  118 . As shown in  FIG. 14 , camera system  94  may be used to view backlight layers  118  and associated equipment in direction  156 . Controller  98  may use information from camera system  94  in aligning backlight layers  118  with each other and with other structures in devices being assembled. Controller  98  may have multiple outputs such as outputs  174  for supplying control signals. For example, controller  98  may issue control signals on outputs  174  that are supplied to inputs  158  of pressurized deionized air dispensers  108 . Control signals on outputs  174  may also be supplied to robotic arm  172  of equipment  100  (e.g., at input  170 ) and to control input  176  of vacuum head  178  of equipment  100 . 
     Equipment  100  may be computer-controlled (robotic) equipment with a gripper formed from vacuum head  178 . When vacuum is applied to a backlight layer  118  using head  178 , the backlight layer will be attached to the underside of head  178  by suction. When the vacuum of head  178  is removed, the backlight layer that is attached to head  178  will be released. 
     In the example of  FIG. 14 , robotic equipment  100  is using vacuum head  178  to pick up backlight layers  118  from backlight layer source  112  and is being used to deposit layers  118  into backlight layer storage frame  114 . Guide structures such as fingers  122  may be used to help center backlight layers  118  on base  120  of frame  114 . Air dispensing systems  108  may be used to supply streams of air that help prevent layers  118  from becoming stuck to each other. Systems  108  may be located around the periphery of holder  114 , around the periphery of film source  112 , and elsewhere in system  90 . 
     System  90  may have multiple stages. For example, system  90  may have a first station that is formed from vacuum head  178  and robotic arm  172  and a second station such as station  164 . Translation stage  102  may be used to move backlight layers  118  between stations in system  90 . For example, stage  102  may be moved in directions  162  to move storage frame  114  between the first and second stations of system  90  and other stations in system  90 . Translation stage  102  may be formed from a carriage that rides on a rail. Motors or other positioning equipment may be used to move the carriage along the rail. Conveyor belts or other translation equipment may be used in system  90 , if desired. 
     The stations in system  90  may perform tasks such as retrieving backlight layers  118  from a source (e.g., source  112 ), assembling backlight layers  118  in a storage frame such as frame  114 , placing backlight layers  118  in a chassis, housing structure, or other support structure, cleaning backlight layers  118 , removing release liner layers from backlight layers  118 , aligning layers  118 , and performing other operations on backlight layers  118 . 
     In the example of  FIG. 14 , arm  172  of robotic system  100  is being used to position vacuum head  178 . Vacuum head  178  may be directed to grip backlight layers. Once a backlight layer has been picked up by vacuum head  178 , computer-controlled arm  172  may position that backlight layer  118  as desired. For example, system  100  may use head  178  to pick up a backlight layer  118  from a stack of layers in source  112  and move that backlight layer  118  to frame  114  in direction  160 . System  100  may then use arm  172  to control the position of the attached backlight layer relative to frame  114  and/or the backlight layers that are already in frame  114 . Air dispensing systems  108  may be used to help control the position of layers  118  (e.g., to help separate the top backlight layer in source  112  from the other backlight layers in source  112 , to help prevent layers  118  from becoming stuck to each other prematurely in frame  114 , to help separate layers in frame  114  when a layer is being removed from frame  114 , etc.). Air sources  108  and system  100  may also be used when mounting backlight layers in housing  12 , a backlight unit chassis, or other support structure. 
     A perspective view of illustrative components that may be used in forming vacuum head  178  is shown in  FIG. 15 . As shown in  FIG. 15 , vacuum head may have manifold structure  178 - 1 , perforated plate  178 - 2 , and porous media layer  178 - 3 . Manifold  178 - 1  may have a cavity such as cavity  180 . Cavity  180  may be rectangular in shape and may be coupled to a source of vacuum. Manifold  178 - 1  distributes the vacuum across the entirety of rectangular perforated plate  178 - 2 . Perforated plate  178 - 2  has an array of openings such as perforations  182 . Perforations  182  may have diameters of 0.5 to 2 mm, less than 2 mm, 1-3 mm, or more than 0.5 mm. Perforations  182  may be arranged in an array of rows and columns or other suitable pattern. In an array configuration, perforations  182  may be provided on a pitch (perforation-to-perforation spacing) of 0.5 to 2 mm, more than 0.5 mm, or less than 2 mm (as examples). 
     Porous media layer  178 - 1  may have fibers  184  or other material that forms small pores. Porous media layer  178 - 1  may, for example, be formed from an open-cell foam, from a fabric, from a mesh, from a fibrous material, or from other material that has small passageways (e.g., less than 0.3 mm, less than 0.5 mm, or more than 0.01 mm in diameter). During operation, vacuum head  178  forms a gripper apparatus that picks up backlight layers  118 . A backlight layer  118  will be attracted to the surface of head  178  that is formed from layer  178 - 3  when vacuum is applied to manifold  178 - 1 . Openings  182  in plate  178 - 2  and porous layer  178 - 3  help regulate the flow of air into the vacuum and help evenly distribute the vacuum across the surface of head  178 . The small pore size of porous layer  178 - 3  creates a gentle suction force that avoids damaging sensitive optical films such as backlight layers  118 . 
       FIG. 16  is a cross-sectional side view of head  178 . As shown in  FIG. 16 , vacuum is applied to the rear of plenum  178 - 1  via vacuum tube  186  and opening  188  in the rear of plenum  178 - 1 . Cavity  180  distributes vacuum across perforated plate  178 - 2  and porous layer  178 - 3 . Layer  178 - 3  preferably has smaller openings than perforations  182  and therefore helps ensure that vacuum head  178  provides gentle suction when activated by controller  98 . 
       FIG. 17  shows how camera system  94  may have cameras such as cameras  94 - 1  and  94 - 2 . There may be one or more cameras, two or more cameras, three or more cameras, or four or more cameras in camera system  94 . Digital image data from the camera(s) in system  94  may be processed by controller  98  to allow controller  98  to automatically control some or all of the operations involved in the assembly of backlight units  42  in system  90 . As shown in  FIG. 17 , for example, each camera in system  94  may inspect a respective corner of backlight layers  118 . Image data from the corners of a backlight layer or stack of backlight layers  118  allows the backlight layers  118  to be aligned with each other or other structures such as illustrative structure  190  of  FIG. 17  (e.g., in lateral dimensions parallel to the plane of layers  118  in the example of  FIG. 17 ). Structures such as structure  190  of  FIG. 17  may include plastic backlight unit chassis structures, plastic chassis structures that include molded plastic over metal frame structures, metal chassis structures, other backlight support structures, metal or plastic housing structures (e.g., portions of housing  12  of device  10 ), or other device structures. Camera system  94  may also be used during operations to align backlight layers  118  to storage frame  114 . 
     The polymer layers that make up backlight layers  118  may initially be coated with sacrificial coatings called release liners. Release liners are thin flexible films that are used to protect layers  118  prior to assembly in a backlight. The release liners are removed from backlight layers  118  before backlight layers  118  are assembled to form backlight unit  42 . 
     A cross-sectional side view of an illustrative backlight layer with release liners is shown in  FIG. 18 . As shown in  FIG. 18 , release liners  192  and  194  may be used to cover backlight layer  118  and thereby protect layer  118  during initial handling (e.g., when shipping layer  118  to a manufacturer, during long-term storage, etc.). As shown in  FIG. 19 , when it is desired to use backlight layer  118  in a backlight unit, upper release liner  192  may be peeled away from upper surface  196  of layer  118  in direction  201  and lower release liner  194  may be peeled away from opposing lower surface  198  of layer  118  in direction  203 . Following removal of release liners  192  and  194 , backlight layer  118  has exposed upper and lower surfaces such as upper surface  196  and lower surface  198 . 
     Release liners  192  and  194  may be removed manually and/or using computer-controlled equipment in system  90  such as release liner removal tool  92 . An illustrative release liner removal tool that is being used to remove release liner  192  from upper surface  196  of backlight layer  118  is shown in  FIG. 21 . As shown in  FIG. 21 , controller  98  may use camera system  94  to monitor backlight layer  118  during release liner removal operations. Release liner removal tool  92  may include robotic (computer-controlled) arm  200  and computer-controlled gripper  208 . Gripper  208  may be a mechanical gripper with claws  202  and  204  that pivot about pivot structure  206 . Claws  202  and  204  may be moved away from each other when it is desired to open gripper  208 . When it is desired to grip an object such as end  192 ′ of release liner  192 , claws  202  and  204  may be moved towards each other. Controller  98  may control the operation of release liner removal tool  92  in real time based on information from camera  94  and/or other information. 
       FIG. 22  shows how backlight layers may be assembled into a support structure such as support structure  190  using system  90  (e.g., using tool  100  and/or other equipment). Support structure  190  may be formed from a portion of housing  12 , may be formed from a backlight unit chassis (plastic, metal, etc.), or may be formed form other structures in device  10  that are configured to receive backlight layers  118 . In the example of  FIG. 22 , the layers that are initially installed in support structure  190  include reflector  80  and light guide plate  78 . Adhesive strip  210  is used to attach reflector  80  to the inner surface of support structure  190 . Adhesive strip  212  is used to attach light guide plate  78  to the inner surface of support structure  190 . Strips  210  and  212  may run into the page in the orientation of  FIG. 22 . Additional backlight layers (e.g., layers  70 - 1 ,  70 - 2 ,  70 - 3 , and  70 - 4 ) may be assembled on top of reflector  80  and light guide plate  78 . 
       FIG. 23  is a diagram showing how structures  190  and backlight layers  118  may be provided with mating alignment features. Structures  190  may, for example, have registration features such as one or more alignment pins  190 ′. Backlight layers  118  may have mating alignment holes  220 . Openings  220  may be circular, rectangular, or other shapes, may be notches that protrude inwardly from an outer peripheral edge in each layer  118 , or may have other suitable configurations. To secure backlight layers  118  to structures  190 , equipment such as adhesive application tool  106  may apply a layer of tape such as tape  214  to the surface of layers  118  and pin  190 ′, thereby attaching layers  118  in place. Tool  106  may have a gripper and robotically controlled equipment such as gripper  208  and computer-controlled arm  200  of equipment  100 . Tape  214  may have a layer of adhesive such as adhesive  216  (e.g., pressure sensitive adhesive) and a flexible polymer carrier such as carrier layer  218 . Other types of adhesive and backlight layer securing structures may be used if desired. The example of  FIG. 23  is merely illustrative. 
     A flow chart of illustrative steps involved in using the equipment of system  90  to assemble backlight layers  118  and other structures into backlight unit  42 , display  14 , and device  10  is shown in  FIG. 24 . 
     At step  222 , housing  12  or other structures for receiving backlight layers  118  may be prepared to receive backlight layers  118 . The structures that receive backlight layers  118  may be portions of housing  12 , a plastic and/or metal backlight chassis structure, or other support structures for backlight layers  118  in backlight unit  42 . The preparation operations of step  222  may include inspection operations and cleaning operations. Adhesive strips such as strips  210  and  212  may be applied to the housing or other support structures along the edges of the support structures (see. e.g., adhesive strips  210  and  212  along the right and opposing left edges of structure  190  of  FIG. 22 ). Adhesive strips may be applied using tool  106  or other equipment in system  90  that is controlled by controller  98 . 
     At step  224 , release liners may be removed from backlight layers  118  using manual and/or automatic techniques. For example, release liners may be removed from reflector  80  and light guide plate  78  using computer-controlled release liner removal tool  92 . During the operations of step  224 , equipment  100  may use vacuum head  178  to position layers  118  in housing  12  and/or a chassis or other support structure  190 . Camera system  94  may be used to gather image data that is used in guiding the placement of layers  118 . If desired, layers  118  may be cleaned using cleaning tool  96  prior to installation in structure  190 . Storage frame  114  may be used to temporarily store backlight layers  118  during processing. Translation stages or other equipment may move layers  118  between processing stations. Air streams may be applied using computer-controlled air sources  108  to help separate backlight layer  118  from each other. 
     At step  226 , release liners may be removed from the upper and/or lower surfaces of other backlight layers  118  such as layers  70 - 1 ,  70 - 2 ,  70 - 3 , and  70 - 4  of  FIG. 7  using manual and/or automatic techniques. For example, release liners may be removed using computer-controlled release liner removal tool  92  or using manual removal techniques. After the release liners have been removed from these backlight layers, these backlight layers may be installed within support structure  190  using equipment  100  or other computer-controlled positioning equipment (e.g., so that alignment features in layers  118  mate with pins or other alignment features on structure  190 ). 
     At step  228 , adhesive tape  214  or other structures may be used to secure layers  118  to support structure  190 . Equipment  106  or other equipment in system  90  may be used to apply tape  214 . Final device assembly may then be completed during the operations of step  230 . During the operations of step  230 , display layers  46  and the backlight unit formed from layers  118  and structure  190  may be assembled to form display  14  and display  14  may be installed within housing  12  with other device structures to form electronic device  10 . 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20140715
Publication Date: 20160906
Grant Date: 20160906
Priority Date: 20140715
Inventors: KORAISHY BABAR M.
Assignee: APPLE INC
CPC Classifications: [{"code": "B32B38/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B37/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B2457/20", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10S901/47", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10S901/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B38/1858", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10S901/09", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0065", "inventive": true, "first": true, "tree": "[]"}, {"code": "B32B2307/202", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "B65H2801/61", "inventive": false, "first": false, "tree": "[]"}, {"code": "B65H3/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "B32B38/162", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B2309/72", "inventive": false, "first": false, "tree": "[]"}, {"code": "B65H3/0816", "inventive": true, "first": false, "tree": "[]"}, {"code": "B32B38/1841", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B2309/72", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B37/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B2307/202", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B38/1858", "inventive": true, "first": false, "tree": "[]"}, {"code": "B65H3/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "B65H3/0816", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10S901/09", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10S901/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B2457/20", "inventive": false, "first": false, "tree": "[]"}, {"code": "B65H2801/61", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B38/162", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10S901/47", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B38/1841", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0065", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "B32B38/10", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 55074452