PATENT DOCUMENT

Publication Number: US-8482713-B2
Application Number: US-201113021183-A
Country: US
Kind Code: B2

Title: Laser processing of display components for electronic devices

Abstract:
Electronic devices may be provided with display structures such as glass and polymer layers in a liquid crystal display. The glass layers may serve as substrates for components such as a color filter layer and thin-film transistor layer. The polymer layers may include films such as a polarizer film and other optical films. During fabrication of a display, the polymer layers and glass layers may be laminated to one another. Portions of the polymer layers may extend past the edges of the glass layers. Laser cutting techniques may be used to trim away excess portions of the polymer layer that do not overlap underlying portions of the glass layers. Laser cutting may involve application of an adjustable infrared laser beam.

Claims:
What is claimed is: 
     
       1. A method of forming electronic device display structures, comprising:
 obtaining at least one display layer; and 
 laser cutting through the display layer to form the electronic device display structures, wherein the electronic device display structures comprise at least one glass layer and wherein laser cutting through the display layer comprises laser cutting through the display layer without cutting the glass layer. 
 
     
     
       2. The method defined in  claim 1  wherein obtaining the at least one display layer comprises obtaining at least one polymer display layer and wherein laser cutting through the display layer comprises laser cutting through the polymer display layer. 
     
     
       3. The method defined in  claim 1  wherein obtaining the at least one display layer comprises obtaining multiple display layers that are attached to each other and wherein laser cutting through the display layer comprises simultaneously laser cutting through each of the multiple display layers. 
     
     
       4. The method defined in  claim 3  further comprising laminating each of the multiple display layers together. 
     
     
       5. The method defined in  claim 3  wherein each of the multiple display layers comprises polymer. 
     
     
       6. The method defined in  claim 3  wherein the multiple display layers include a polarizer layer. 
     
     
       7. The method defined in  claim 1  wherein the display layer comprises a layer selected from the group consisting of: a polarizer layer, a touch sensor substrate layer, an antireflection layer, and a display cover layer. 
     
     
       8. The method defined in  claim 1  wherein laser cutting through the display layer comprises applying an infrared laser beam having a wavelength in the range of 1 to 20 microns to the display layer. 
     
     
       9. A method of forming electronic device display structures, comprising:
 obtaining at least one display layer; and 
 laser cutting through the display layer to form the electronic device display structures, wherein laser cutting through the display layer comprises applying a laser beam with a spot diameter of 100 microns to 500 microns to the display layer. 
 
     
     
       10. The method defined in  claim 1  wherein laser cutting through the display layer comprises applying a laser beam with an elongated spot shape to the display layer. 
     
     
       11. The method defined in  claim 1  wherein laser cutting through the display layer comprises applying a laser beam with a shape that changes as a function of position on the display layer when cutting the display layer. 
     
     
       12. The method defined in  claim 1  wherein the at least one display layer comprises at least one polymer layer, wherein the at least one glass layer is attached to the at least one polymer layer, and wherein laser cutting through the display layer comprises cutting the at least one polymer layer without cutting the at least one glass layer. 
     
     
       13. The method defined in  claim 12  wherein the at least one glass layer comprises a glass layer selected from the group consisting of: a liquid crystal display color filter array layer, a liquid crystal display thin-film-transistor layer, and a cover glass layer and wherein the at least one polymer layer comprises a polymer layer selected from the group consisting of: a polarizer layer, an antireflection layer, and a polymer touch sensor substrate layer. 
     
     
       14. The method defined in  claim 1  wherein the at least one glass layer has an edge and wherein laser cutting the display layer comprises laser cutting along the edge to trim away excess portions of the display layer that do not overlap the glass layer. 
     
     
       15. The method defined in  claim 14  further comprising:
 laminating the glass layer and the display layer together using adhesive before laser cutting along the edge to trim away the excess portions of the display layer. 
 
     
     
       16. A method, comprising:
 forming display structures including at least one glass substrate layer and at least one display layer having portions that overlap the glass substrate layer and having portions that do not overlap the glass substrate layer; and 
 with a laser, laser cutting away the portions of the display layer that do not overlap the glass substrate layer, wherein laser cutting away the portions of the display layer comprises applying an infrared laser beam with a spot having at least one lateral dimension of 100 to 500 microns to the display layer. 
 
     
     
       17. The method defined in  claim 16  wherein the display layer comprises a polymer display layer and wherein laser cutting away the portions of the display layer comprises laser cutting away the portions of the polymer display layer. 
     
     
       18. The method defined in  claim 17  wherein the glass layer comprises a color filter layer having edges and wherein laser cutting away the portions of the polymer display layer comprises applying the infrared laser beam to the polymer display layer along the edges of the color filter layer. 
     
     
       19. The method defined in  claim 18  further comprising:
 laminating the polymer display layer to the color filter layer with adhesive before laser cutting away the portions of the polymer display layer. 
 
     
     
       20. The method defined in  claim 16  wherein laser cutting away the portions of the display layer comprises laser cutting away the portions of the display layer using a laser beam with a non-Gaussian intensity profile.

Description:
BACKGROUND 
     This relates generally to manufacturing techniques for electronic devices, and, more particularly, to use of laser processing techniques in the construction of electronic device structures such as display structures 
     Displays are widely used in electronic devices to display images. Displays such as liquid crystal displays display images by controlling liquid crystal material associated with an array of image pixels. A typical liquid crystal display has a color filter layer and a thin-film-transistor layer between which the liquid crystal material is interposed. Polarizer layers may be formed on the upper and lower surfaces of the color filter layer and thin-film-transistor layer. Additional optical films may also be present. 
     As part of the process of forming a liquid crystal display, it is necessary to cut sheets of polarizer film and other optical films to size. For example, when forming a display for a handheld device such as a cellular telephone, it is necessary to form a small rectangular piece of polarizer film for the cellular telephone display. After the desired piece of optical film has been cut from a larger sheet, it can be laminated to other structures to form a finished display. 
     Die cutting techniques are typically used to cut rectangular pieces of polarizer film and other optical films from larger sheets. Difficulties can arise, however, in maintaining desired manufacturing tolerances during die cutting and lamination processes during display fabrication. 
     It would therefore be desirable to be able to provide enhanced techniques for manufacturing displays for electronic devices. 
     SUMMARY 
     Displays for electronic devices may be formed by laminating display layers together. The display layers in a display may include glass layers such as glass substrate layers associated with a color filter array and a thin-film transistor layer or other structures. The display layers may also include layers of other materials. As an example, the display layers may include optical films such as compensating films, diffusers, polarizers, antireflection coatings, and other layers formed from materials such as polymers. 
     In fabricating a display, layers of the display may be attached to one another using adhesive. With one suitable arrangement, glass layers for the display may be cut to their final size. Slightly oversized polymer layers may be attached to the surface of the glass layers. The polymer layers may be sized so that portions of the polymer layers do not overlap the glass layers, but rather overhang the edges of the glass layers. 
     Laser cutting techniques may be used in trimming away these excess portions of the polymer layers. For example, an infrared laser beam may be applied along the edge of the glass layers to remove the overhanging parts of the polymer layers. The resulting structure will have polymer layers with edges that are in alignment with the edges of the glass layers. 
     The size and shape of the laser spot that is created on the display layers during laser cutting operations can be adjusted. For example, the spot can be elongated when cutting along straight edges for a display and can be formed into a more circular shape when cutting along curved portions of a display such as around display corners. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a system of the type that may be used in fabricating display structures for an electronic device using laser processing techniques in accordance with an embodiment of the present invention. 
         FIG. 2A  is a perspective view of an illustrative electronic device such as a handheld electronic device that may be provided with a display that has been fabricated using laser processing techniques in accordance with an embodiment of the present invention. 
         FIG. 2B  is a perspective view of an illustrative electronic device such as a portable computer that may be provided with a display that has been fabricated using laser processing techniques in accordance with an embodiment of the present invention. 
         FIG. 3  is a cross-sectional side view of an illustrative display containing layers of material of the type that may be processed using a laser cutting system in accordance with an embodiment of the present invention. 
         FIG. 4A  is a cross-sectional side view of illustrative display structures showing how display layers such as polymer optical films may be trimmed using laser cutting techniques in accordance with an embodiment of the present invention. 
         FIG. 4B  is a cross-sectional side view of the illustrative display structures of  FIG. 4A  following laser trimming to remove excess portions of the optical films in accordance with an embodiment of the present invention. 
         FIG. 5  is a diagram of an illustrative laser processing system showing how laser cutting equipment may produce a controlled laser beam for use in cutting layers of material during fabrication of a display for an electronic device in accordance with an embodiment of the present invention. 
         FIG. 6  is a cross-sectional side view of display structures including layers such as an antireflection coating layer and a touch sensor layer that are being trimmed to align the edges of these layers with other display layers in a display in accordance with an embodiment of the present invention. 
         FIG. 7A  is a cross-sectional side view of illustrative display structures that include display layers such as a color filter array layer and a thin-film-transistor layer and an associated polymer film such as a layer of polarizing material that is being cut using laser cutting equipment in accordance with an embodiment of the present invention. 
         FIG. 7B  is top view of the illustrative display structures of  FIG. 7A  showing where alignment marks may be located on the display structures in accordance with an embodiment of the present invention. 
         FIG. 8A  is a diagram showing how a laser beam may be directed toward a workpiece parallel to a surface normal associated with the exposed surface of a workpiece in accordance with an embodiment of the present invention. 
         FIG. 8B  is a diagram of an illustrative laser beam spot of the type that may be associated with the laser beam of  FIG. 8A  on the surface of the workpiece in accordance with an embodiment of the present invention. 
         FIG. 9A  is a diagram showing how a laser beam may be directed toward a workpiece at a non-zero angle with respect to a surface normal associated with the exposed surface of a workpiece in accordance with an embodiment of the present invention. 
         FIG. 9B  is a diagram of an illustrative laser beam spot of the type that may be associated with the laser beam of  FIG. 9A  on the surface of the workpiece in accordance with an embodiment of the present invention. 
         FIG. 10  is a graph in which laser beam intensity has been plotted as a function of position for a laser beam with a round cross section of the type that may be used in cutting layers of material for a display in accordance with an embodiment of the present invention. 
         FIG. 11  is a graph in which laser beam intensity has been plotted as a function of position for a laser beam with an elongated cross section of the type that may be used in cutting layers of material for a display in accordance with an embodiment of the present invention. 
         FIG. 12  is a diagram showing how a laser cut may be made by translating a laser beam with an elongated cross section along a direction parallel to the longitudinal axis of the beam cross section in accordance with an embodiment of the present invention. 
         FIG. 13A  is a diagram showing how a laser beam with a circular cross-sectional profile may be used in cutting optical films into shapes with curved edges in accordance with an embodiment of the present invention. 
         FIG. 13B  is a top view of a portion of a laser-cut structure such as an display layer that has been cut using a laser with a circular cross section in accordance with an embodiment of the present invention. 
         FIG. 14  is a diagram showing how a laser beam with a variable-shape cross-sectional profile may be used in cutting display layers into shapes with curved edges in accordance with an embodiment of the present invention. 
         FIG. 15  is a flow chart of illustrative steps involved in using laser processing techniques in forming electronic device structures such as display structures in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Displays are widely used in electronic devices. For example, displays may be used in computer monitors, laptop computers, media players, cellular telephones and other handheld devices, tablet computers, televisions, and other equipment. Displays may be based on plasma technology, organic light-emitting-diode technology, liquid crystal structures, etc. 
     Displays generally include layers of materials. For example, a liquid crystal display may include a color filter array layer that includes colored filter elements, a thin-film transistor layer that includes thin-film transistors for controlling the application of electric fields to liquid crystal image pixels. A cover layer may be used to cover the display. The cover layer and other display layers such as the colored filter array layer and thin-film-transistor layer are typically formed from glass but may, if desired, by formed from other substrate materials such as polymers. 
     Numerous additional display layers are generally associated with a display. For example, a typical liquid crystal display may include layers associated with polarizers, antireflection coatings, substrates for touch sensor arrays, birefringent (compensating) films, light guide plates, diffusers, etc. These layers, which are sometimes referred to as optical films are often formed from polymers. 
     In conventional display fabrication arrangements, glass layers may be cut using scribe-and-break techniques. Polymer layers may conventionally be cut using die stamping techniques. Layers that have been cut in this way may be laminated using lamination equipment. 
     To enhance throughput and alignment accuracy relative to conventional display fabrication methods, laser cutting techniques may be used to cut electronic device structures such as the layers associated with an electronic device display. Polymers can be readily cut using lasers such as infrared lasers, so the use of laser cutting to trim polymer layers with respect to other display layers is sometimes described herein as an example. If desired, other display layers such as display layers formed from glass, ceramic, carbon-fiber composites and other materials may be patterned using laser processing techniques. The cutting of display layers formed from material such as polymers is merely an example. 
     A schematic diagram of an illustrative laser cutting system is shown in  FIG. 1 . As shown in  FIG. 1 , laser cutting equipment  10  may include a laser such as laser  12  and beam shaping and positioning equipment  16 . Equipment  10  may shape and position laser beam  14  on workpiece  18 . Workpiece  18  may include display structures such one or more layers of material in a display or other suitable electronic device structures (e.g., one or more layers of polymer, one or more layers of glass, one or more layers of ceramic, one or more fiber-based composite layers, combinations of such layers, etc.). 
     Laser  12  may be, for example, a continuous wave (CW) or pulsed laser that produces light at wavelengths from about 150 nm to about 20 microns (e.g., light at ultraviolet, visible, or infrared wavelengths), and, more preferably a laser that produces infrared light at a wavelength in the range of 1 to 20 microns, 1 to 12 microns, or 9 to 12 microns. In the infrared spectrum, high-power laser sources are widely available and most polymers are at least somewhat opaque and able to readily absorb incoming laser light. An example of a laser type that may be used for laser  12  is a carbon dioxide (CO 2 ) laser that produces light at one or more wavelengths in the range of about 9.2 to 11.4 microns). Other types of lasers may be used and other wavelengths of laser light may be generated. For example, laser  12  may be a diode laser, a solid state laser, a gas laser other than a CO2 laser, or any other suitable type of laser. 
     Laser  12  may produce a pulsed or CW laser beam such as beam  14 . The shape of beam  14  and the position of beam  14  relative to workpiece  18  may be controlled using beam shaping and positioning equipment  16 . Equipment  16  may include optical components such as lenses, metallized mirrors, mirrors formed from prisms, mirrors formed from dielectric stacks, diffusers, beam conditioners, filters, deformable mirrors, adjustable shutters, and other optical components. Equipment  16  may also include positioners such as motors, solenoids, and other components that can control the position of the optical components of beam shaping and positioning equipment  16  relative to workpiece  18  (e.g., by rastering the beam across the surface of workpiece, by laterally translating the beam and/or workpiece  18  relative to each other, by adjusting the distance between optical components in equipment  16 , be deforming deformable optical structures, etc.). 
     In a typical scenario, laser  12  may produce about 10 to 100 W of output power or other suitable amounts such as less than 50 W of power, more than 20 W of power, etc. Beam  14  may be focused to a spot on workpiece  18  that has a spot size (e.g., a 1/e 2  diameter) of about 100 to 500 microns in diameter. Under laser illumination conditions such as these, optical films such as polarizer layers and other polymer layers in workpiece  18  will be cut (e.g., by thermal disassociation of the bonds in the polymer material or other decomposition mechanisms such as ablation). 
     A perspective view of an illustrative electronic device such as a handheld electronic device that may be provided with a display containing laser-cut materials such as layers processed using laser processing equipment  10  of  FIG. 1  is shown in  FIG. 2A . As shown in  FIG. 2A , electronic device  20  may have a housing such as housing  22 . Housing  22  may be formed from materials such as plastic, glass, ceramic, metal, fiber composites, and combinations of these materials. Housing  22  may have one or more sections. In the arrangement of  FIG. 2A , device  20  has a front face and a rear face. Display  24 , which may be formed from display structures in workpiece  18  of  FIG. 1 , may be mounted on the front face of housing  22 . Openings  26  may be provided in display  24 . For example, openings  26  may be used to form speaker ports, button openings, and other openings in a cover glass layer for display  24  or in other display layers. 
     A perspective view of another illustrative electronic device of the type that may be provided with a display that has been fabricated using laser processing equipment such as laser processing equipment  10  of  FIG. 1  is shown in  FIG. 2B . In the example of  FIG. 2B , housing  22  has upper portion  22 A and lower portion  22 B. Portions  22 A and  22 B may be attached using a hinge. Upper portion  22 A may be used to house display  24 . Processing circuitry and input-output components such as track pad  28  and keyboard  30  may be provided in lower portion  22 B. Device  20  of  FIG. 2B  may be, for example, a portable computer. 
     In other illustrative electronic devices (e.g., tablet computers, music players, etc.), displays such as display  24  and other electronic device components may be mounted in housings  22  with other configurations. The display mounting arrangements of  FIGS. 2A and 2B  are merely illustrative. 
     A cross-sectional side view of an illustrative display of the type that may be incorporated into an electronic device is shown in  FIG. 3 . The illustrative display of  FIG. 3  is a liquid crystal display (as an example). Other types of displays may be provided for electronic devices if desired. 
     As shown in  FIG. 3 , display  24  may include color filter layer  32  (sometimes referred to as a color filter array layer) and thin-film-transistor layer  34 . Color filter layer  32  may include an array of colored filter elements. In a typical arrangement, the pixels of layer  32  each include three types of colored pixels (e.g., red, green, and blue subpixels). Liquid crystal layer  36  includes liquid crystal material and is generally interposed between color filter layer  32  and thin-film-transistor layer  34 . Thin-film-transistor layer  34  may include electrical components such as thin film transistors, capacitors, and electrodes for controlling the electric fields that are applied to liquid crystal layer  36 . 
     Optical film layers  38  and  40  and display layers  42  may be formed above and below color filter layer  12 , liquid crystal layer  16 , and thin-film-transistor layer  14 . Optical films  18  and  20  may include structures such as quarter-wave plates, half-wave plates, diffusing films, optical adhesives, and birefringent compensating layers. Display layers  42  may include films of this type and/or other display structures such as a cover glass layer or polymer cover layer, an antireflection coating layer, coatings for resisting fingerprints and scratching, a touch sensor array (e.g., a touch sensor array of transparent capacitive electrodes such as indium tin oxide electrodes patterned on a clear substrate such as a glass or polymer substrate), etc. 
     Display  24  may have upper and lower polarizer layers  44  and  46 . Backlight  48  may provide backside illumination for display  24 . Backlight  48  may include a light source such as a strip of light-emitting diodes. Backlight  48  may also include light-guide plate  48 A and back reflector  48 B. Back reflector  48 B may be located on the lower surface of the light-guide plate to prevent light leakage and may be formed from a polymer such as white polyester or other reflective materials. Light-guide plate  48 A may be formed from a clear polymer. Light from the light source may be injected into an edge of the light-guide plate and may scatter upwards in direction  50  through display  24 . Layers of adhesive may be interposed between the layers of display  24  during assembly. 
     The layers of material in display  24  may be formed from any suitable materials. Typical display layers above those in backlight  48  are transparent to allow light to propagate in direction  50 . Suitable display layer materials include polymers, glass, ceramic, fiber-based composites, etc. In a typical arrangement, the cover layer in layer  42  may be formed from a glass plate, the substrates for color filter layer  32  and thin-film-transistor layer  34  may be formed from glass panels, and glass or polymer may be used for forming an optional planar touch sensor array substrate for a touch sensor in layers  42 . The other layers of material in display  24  (e.g., the coating layers and other display layers in layers  42 , upper and lower polarizers  44  and  46 , optical films  40  and  46 , and the layers in backlight  48 ) are typically formed from polymers. This is, however, merely an example. In some displays, some of the layers that are often formed form polymers may be formed form glass, ceramic, or other materials and some of the layers that are often formed from glass layers may be formed from polymer, ceramic, or other materials. Polymer layers tend to be cut at lower laser power densities than non-polymer layers, so the use of laser processing equipment  10  of  FIG. 1  to cut through polymer layers in the structures of display  24  is generally described herein as an example. As described in connection with  FIG. 1 , laser processing equipment  10  may be used in processing glass display layers or other non-polymer electronic device structures if desired. 
     The use of laser processing equipment  10  to cut polymers in structures such as display  24  is illustrated in the example of  FIGS. 4A and 4B . In the example of  FIGS. 4A and 4B  and other illustrative examples described herein, the structures that make up some or all of display  24  are sometimes referred to as forming a workpiece (i.e., workpiece  18  of  FIG. 1 ), because laser processing equipment  10  is being used to process these structures to form a display or other desired finished electronic device structures. 
       FIG. 4A  is a cross-sectional side view of a workpiece (workpiece  18 ) having one or more layers  18 A and one or more layers  18 B. Layers  18 A may be polymer display layers such as optical films, polymer coatings, polymer touch panel substrates, polarizers, etc. Layers  18 B may be glass or ceramic display layers such as a color filter array layer, a thin-film-transistor layer, etc. Layers  18 A may be located on the upper surface of workpiece  18  on top of layers  18 B or may be interspersed among layers  18 B. 
     In the scenario illustrated in  FIG. 4A , layers  18 A have been precut to a size that is somewhat larger than layers  18 B. Layers  18 B may, for example, be cut using a scribe-and-break process that creates a desired rectangular display footprint and layers  18 A may be die cut to a size that is slightly larger than the nominal rectangular shape for layers  18 B. Other techniques for cutting layers  18 A and  18 B may be used, if desired. 
     Over-sizing layers  18 A with respect to layers  18 B creates an overhanging portion such as portion  52  that does not overlap the “footprint” of layers  18 B (i.e., a portion that does not overlap the area of layers  18 B when viewed along vertical dimension Z). Central portion  54  of layers  18 A may overlap layers  18 B. Although only one overlapping edge portion  52  of layers  18 A is shown in  FIG. 4A , there may be, for example, four overlapping edge portions  52 , each of which is associated with a respective one of four edges  56  of a rectangular set of layers  18 B (e.g., the four peripheral edges of a rectangular display). 
     By applying laser beam  14  to layers  18 A in alignment with edge  56  of layers  18 B, non-overlapping edge portion  52  of layers  18 A may be trimmed from main overlapping portion  54  of layers  18 A. After trimming excess portions of layers  18 A from workpiece  18  in this way, workpiece  18  may appear as shown in  FIG. 4B . As shown in  FIG. 4B , portion  52  of layers  18 A is no longer present following laser trimming, so that edge  56  of layers  18 A is aligned with edge  56  of layers  18 B. The accuracy of this type of laser trimming may surpass the accuracy associated with typical die cutting and lamination processes. For example, using a spot size of less than 0.05 mm and positioning techniques that are able to locate beam  14  relative to edge  56  of layers  18 B within +/−0.05 mm, the location of trimmed edge  56  of layers  18 A may be aligned to the edge of layers  18 B within +/−0.1 mm, whereas conventional die cut processes typically exhibit size tolerances of 0.2 mm and conventional lamination processes typically exhibit edge location tolerances of about 0.2 mm. 
       FIG. 5  is a diagram of illustrative laser processing equipment  10  of the type that may be used in cutting through display structures such as polymer display films or in cutting other suitable electronic device structures. As shown in  FIG. 5 , equipment  10  may include a control unit such as control unit  58  that is interconnected with other electronic components in equipment  10  using one or more communications paths  74 . Control unit  58  may use a camera such as camera  60  or other sensors to monitor the position of laser beam  14  on surface  62  of workpiece  18 . For example, control unit  58  may use camera  60  to detect edges and alignment marks on workpiece  18  to facilitate accurate positioning of the laser spot on workpiece  18 . Control unit  58  may be based on computing equipment such as one or more processors, memory chips, networked computers, stand-alone computers, and other computing equipment. A user may manually control the operation of components in system  10  using buttons, knobs, and other user input interface components that are associated with the components of system  10  and/or by using a touch screen, on-screen options, keyboard, buttons, mouse, or other user input interface components associated with control unit  58 . Control unit  58  may also automatically control equipment  10  (e.g., based on sensor input such as input from camera  60 ). 
     Control unit  58  may issue control signals that control the operation of one or more positioners  64 . Positioners  64  may be associated with the components of laser processing system  10  such as laser  12 , beam shaping equipment  66 , optical components  68  (e.g., mirrors, lenses, etc.), and workpiece  18 . Positioners  64  may include motors, solenoids, and other suitable equipment for making position adjustments. Position adjustments may be made in linear dimensions X, Y, and Z and in any of the rotational (angular) positions about these axes. 
     Laser beam  14  may be shaped using optical components  66  and  68 . Components  66  and  68  may include lenses, filters, mirrors, and other optical components for shaping and positioning beam  14  relative to workpiece  18 . For example, components  66  may include lenses and other components for homogenizing or otherwise conditioning beam  14 . Components  66  may be interposed within beam  14  at one or more locations. The illustrative configuration of  FIG. 5  in which components  66  lie between laser  12  and optical components  68  is merely illustrative. 
     Optical components  68  such as mirrors and other components may be positioned using positioners  64 . By laterally translating mirrors or other optical components, the lateral position of beam  14  may be controlled. For example, control unit  58  may direct a positioner on which a mirror has been mounted from position  70  to position  72 , thereby translating reflected beam  14  so that it passes along path  14 ″ rather than path  14 ′. Rotational control of components  68  (e.g., mirrors) may also be used in adjusting the relative position of beam  14  an workpiece  18 . For example, by rotating a mirror or other component  68 , beam  14  may be deflected so that it passes along path  14 ′″ rather than path  14 ′. Combinations of beam rastering (e.g., positioner adjustment to deflect beam  14  at a desired angle θ) and translation (e.g., positioner adjustment to change the lateral position of beam  14  by a desired amount ΔX) may be used in controlling beam placement if desired. Control unit  58  may also control the output power from laser  12  by issuing control commands over communications path  74  and may control the state of deformable mirrors and other optical components  66  and  68  (e.g., to adjust beam intensity profiles, beam shapes, etc.). 
       FIG. 6  shows how laser  12  may be used to trim portions of a workpiece that includes a touch sensor layer (e.g., touch sensor layer  90 , which may have a polymer substrate and conductive indium-tin-oxide capacitor electrodes for forming a capacitive touch sensor array). During trimming, laser beam  14  may be used to remove portion  52  of layers  18 A. Layers  18 A may be (for example) polymer layers including layer  92  (e.g., an antireflection layer or other coating layer), touch sensor layer  90 , and layer  94  (e.g., a polarizer layer, other optical films, etc.). Laser beam  14  may have sufficient intensity to cut through all of layers  18 A simultaneously. In scenarios in which layers  18 B are formed form a durable substrate material such as glass or ceramic, stray light from beam  14  will not generally affect layers  18 B (i.e., layers  18 B will not be cut) during the trimming process that removes excess portions of layers  18 A. 
       FIG. 7   a  shows how laser beam  14  may be used to remove polymer layers  18 A (e.g., a polarizer layer and/or other optical films) from underlying glass or ceramic layers  18 B (e.g., color filter array layer  98  and thin-film transistor layer  96 ). Camera  60  may be used to capture images of layers  18 A and  18 B. For example, camera  60  may be used to view the position of edge  56  of layers  18 B. Control unit  58  ( FIG. 5 ) may control beam shaping and positioning equipment  16  so as to position beam  14  relative to workpiece  18  with beam  14  in alignment with edge  56 . Control unit  58  may determine how to adjust beam shaping and positioning equipment  16  in response to manual operator input and/or automatic image recognition software running an edge detection routine or other control algorithms on control unit  58 . 
     To assist a user of equipment  10  and/or the automatic image recognition software running on control unit  58  in accurately determining the location of workpiece  18  (e.g., features such as edge  56  of workpiece  18 ), one or more of the layers of workpiece  18  may be provided with visual markers such as alignment marks  100  on color filter layer  98  in the  FIG. 7A  example. Alignment marks  100  may assist equipment  10  in locating edges such as edge  56  and in accurately positioning beam  14  in alignment with edges such as edge  56  during laser cutting operations. Alignment marks  100  may have any suitable shape (crosses, dots, lines, squares, etc.) and may be formed from metal or other suitable materials.  FIG. 7B  is a top view of color filter layer  98  of  FIG. 7A  showing how alignment marks  100  may be placed at the four corners of workpiece  18  (as an example). 
     It may be desirable to adjust the shape of beam  14  during laser processing operations. For example, it may be desirable to elongate the cross-sectional shape of beam  14  in some situations and to ensure that the cross-sectional shape of beam  14  (i.e., the shape of the laser spot formed when beam  14  strikes the workpiece) is circular in other situations. Laser spot shapes may be modified by controlling the settings and positions of optical components in the path of beam  14  and/or by controlling the orientation of workpiece  18  relative to beam  14 . Examples of components that may be used in shaping and positioning beam  14  (e.g., components in optical components  66  and/or components  68  of  FIG. 5  or other components in the path of beam  14 ) include lenses, metallized mirrors, mirrors formed from prisms, mirrors formed from dielectric stacks, diffusers, beam conditioners, filters, deformable mirrors, adjustable shutters, and other optical components. 
     An example of beam shaping by equipment  10  is shown in  FIGS. 8A ,  8 B,  9 A, and  9 B. In this example, laser spot shape is altered by adjusting the incident angle of beam  14  on surface  62  of workpiece  18 . If desired, other techniques may be used in shaping beam  14  (e.g., deforming beam  14  using adaptive optics such as deformable mirrors, etc.). The example of  FIGS. 8A ,  8 B,  9 A, and  9 B is merely illustrative. 
     In the scenario illustrated in  FIG. 8A , laser beam  14  is being directed onto surface  62  of workpiece  18  with an orientation that is parallel to surface normal S (i.e., laser beam  14  is parallel to surface normal S and is perpendicular to the plane of surface  62 ). Beam  14  (in this example) has a circular cross-sectional profile before striking surface  62 . As a result, beam  14  makes a circular spot when striking surface  62 , as shown in  FIG. 8B . 
     Using beam shaping and positioning equipment  16  of  FIG. 1  (e.g., using positioners  64 , laser  12 , and optical components such as components  66  and  68  of  FIG. 5 ), control unit  58  can adjust the orientation of laser beam  14  relative to workpiece  18  so that laser beam  14  is directed onto surface  62  of workpiece  18  with an orientation that is not parallel to surface normal S. In this situation, laser beam  14  is at a non-zero angle A with respect to surface normal S and is not perpendicular to the plane of surface  62 , as shown in  FIG. 9A . Beam  14  (in this example) has a circular cross-sectional profile before striking surface  62  of workpiece  18  in  FIG. 9A , but the non-zero angle of incidence A of laser beam  14  in the scenario of  FIG. 9A  causes beam  14  so spread out when striking surface  62 . As a result, beam  14  makes an elongated spot when striking surface  62 , as shown by the elliptical spot for beam  14  in  FIG. 9B . 
     In elongated spot shapes such as the elongated spot of  FIG. 9B , the lateral dimension of the spot is larger parallel to longitudinal axis  76  than along transverse axis  78 . For example, the size of the spot along axis  78  may be about 100 to 500 microns and the size of the spot along axis  76  may be about 100 microns to 1000 microns, in the range of 100 microns to 1 mm, in the range of 100 microns to 2 mm, in the range of 100 microns to 4 mm, etc. By controlling the power of laser  12 , the power density of the elongated spot shape on surface  62  of  FIG. 9B  may be decreased, maintained at the same level, or increased relative to the circular spot shape of  FIG. 8B . 
     If desired, beam (spot) shaping and positioning equipment  16  ( FIG. 1 ) may be used in controlling the intensity profile of beam  14 . Illustrative intensity profiles for beam  14  in two different operating scenarios are shown in  FIGS. 10 and 11 . In  FIGS. 10 and 11 , beam intensity is plotted as a function of lateral distance X transverse to the propagation axis of laser beam  14  (i.e., across the width of the spot). 
     A typical Gaussian profile of the type that may be associated with beam  14  and the associated laser spot on workpiece  18  is shown in  FIG. 10 . As shown by curve  80  of  FIG. 10 , a Gaussian intensity distribution is characterized by relatively gradual beam edges (i.e., intensity tapers off somewhat gradually as a function of increasing lateral distance X from the center of the beam). 
     Using beam shaping and positioning equipment  16 , a beam profile of the type shown in  FIG. 11  may be produced for laser beam  14 . As shown by curve  84  of  FIG. 11 , a laser beam that has been shaped to form the profile of  FIG. 10  may have a portion such as central portion  86  that does not monotonically increase in power and may also be characterized by an intensity falloff at the edges of the laser beam that is more abrupt that of the Gaussian beam of  FIG. 10 . This enhanced sharpness at the boarder of the laser spot may help create sharper, more distinct cuts when cutting polymer display layers in workpiece  18 . The non-Gaussian laser intensity profile of  FIG. 11  is merely illustrative. Other non-Gaussian laser intensity profiles may be used for laser beam  14  during laser cutting of display structures if desired. 
       FIG. 12  shows how a laser beam that has been used to form an elongated laser spot  14 E on the surface of workpiece  18  may be used in forming a straight cut through workpiece  18 . Elongated laser spot  14 E may, as an example, be produced by adjusting the angle of incidence of beam  14  or using adjustable optics in beam shaping and positioning equipment  16  as described in connection with  FIGS. 9A and 9B . In the illustrative scenario of  FIG. 12 , the laser beam is being moved in direction  102 , parallel to axis  104  of the straight cut being formed in the workpiece. 
     When forming a curved cut (e.g., when trimming excess in display layers  18 A that overhangs a curved corner portion of display layers  18 B), it may be desirable to use a circular laser spot of the type shown in  FIG. 8B . This type of arrangement is illustrated in the example of  FIG. 13A  in which circular laser spot  14 C is being moved along a curved path by beam shaping and positioning equipment  16 .  FIG. 13B  shows how this may result in layers  18 A with a curved cut (e.g., a curved corner along edge  56 ). The curved cut of  FIG. 13B  may help trim excess from layers  18 A so that layers  18 A and  18 B are accurately aligned along a curved edge  56  in underlying layers  18 B. 
     If desired, beam shaping and positioning equipment  16  may be used to adjust the shape of the laser spot produced by laser beam  14  in real time during trimming operations. As shown, for example, in  FIG. 14 , in some portions of a cut such as along curved portions of edge  56 , the laser spot may be circular or nearly circular (see, e.g., circular spot shape  14 C) and in other portions of the cut (e.g., along straight portions of edge  56 ), the laser spot may be adjusted by equipment  16  to have an elongated shape such as elongated spot shape  14 E. Real time adjustments may also be made to the intensity profile of laser beam  14  by equipment  16  (e.g., to use a gradual intensity profile such as the Gaussian profile of  FIG. 10  in some situations and to use a less gradual intensity profile such as the profile of  FIG. 11  in other situations). Intensity profile adjustments and other beam adjustments (e.g., spot shape adjustments) may be made to accommodate differences in cutting speeds, differences in the material being cut, differences in edge position, etc. 
       FIG. 15  is a flow chart of illustrative steps involved in using laser processing equipment  10  of  FIG. 1  in fabricating display structures and other electronic device structures for electronic device  20 . 
     At step  106 , layers of material for the electronic device structures such as glass display layers (e.g., layers  18 B) and oversized polymer layers (e.g., layers  18 A) may be obtained and formed in appropriate sizes. For example, some or all of display layers  18 B may be formed using scribe-and-cut techniques or other arrangements suitable for cutting glass substrates (as an example). Layers  18 A may be cut to size using die cutting, laser cutting, or other cutting techniques suitable for cutting polymer sheets (as an example). 
     At step  108 , layers  18 A and layers  18 B may be attached to one another using adhesive or other fastening techniques. For example, layers  18 A and  18 B may be laminated to one another using interposed layers of adhesive (e.g., pressure sensitive adhesive, optically clear adhesive, thermally cured adhesive, ultraviolet-light-cured adhesive, etc.). Lamination equipment may be used in laminating layers  18 A and  18 B together. 
     Following lamination, some of layers  18 A will generally overhang edges  56  (i.e., excess portions of layers  18 A will protrude over the sides of layers  18 B and will not overlap layers  18 B). During the operations of step  110 , laser processing equipment  10  may use beam shaping and positioning equipment  16  to remove the excess portions of layers  18 A or to otherwise use laser beam  14  to shape and cut workpiece  18 . Beam shaping and positioning equipment  16  may make adjustments to the lateral and angular position of beam  14  relative to workpiece  18  and adjustments to beam  14  that control the shape of the laser spot on the surface of the workpiece and other laser processing parameters (e.g., the speed of spot movement relative to workpiece  18 , the power of laser  12 , etc.). Multiple beams  12  may be directed onto workpiece  18  at the same time, if desired (e.g., to form multi-beam spots or to process different portions of edge  56  simultaneously to increase throughput). 
     Following laser processing to trim excess portions of layers  18 A from layers  18 B of workpiece  18  or to otherwise laser process workpiece  18 , workpiece  18  (i.e., a trimmed display) may be installed in an electronic device. For example, a finished display such as display  24  of  FIGS. 2A and 2B  may be installed in housing  22  of electronic device  20  using electronic device assembly equipment. 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20110204
Publication Date: 20130709
Grant Date: 20130709
Priority Date: 20110204
Inventors: QI JUN
FU WAYNE H.
WANG CHENHUI
LIN KUANYING
GUPTA NATHAN K.
YIN VICTOR H.
Assignee: APPLE INC
CPC Classifications: [{"code": "Y10T156/1348", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/38", "inventive": true, "first": true, "tree": "[]"}, {"code": "B23K26/402", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K2103/50", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2793/0027", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2793/0027", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K2103/50", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T156/108", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B38/105", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T156/108", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/0876", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/103", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/38", "inventive": true, "first": true, "tree": "[]"}, {"code": "B23K2103/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K2103/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T156/1348", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 46585323