Patent Publication Number: US-2019196252-A1

Title: Ultra-thin display assembly with integrated touch functionality

Description:
BACKGROUND 
     Field of the Disclosure 
     This disclosure relates generally to portable information handling systems and, more particularly, to ultra-thin display assemblies with integrated touch functionality for portable information handling systems. 
     Description of the Related Art 
     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
     Liquid crystal displays (“LCDs”) are commonly employed for portable information handling systems configured in the form of laptop, notebook, netbook, and tablet computers, among others. Another type of display technology used in portable information handling systems is an organic light emitting diode (“OLED”), in which individual pixels, generated by individual electrochemical cells formed from a layer of organic materials, are sandwiched between two electrode layers. Since the individual pixel cells of an OLED generate light, an OLED may be used without a backlight element. The LCD and/or OLED screen of a typical laptop computer may be mounted within a display housing that is hingeably attached to a base housing that contains the keyboard for the notebook computer. Recently various designs for portable information handling systems have been introduced that combine conventional laptop and tablet functionality and may employ various types of connections to a base housing, including various types hinges and/or removable attachment mechanisms. Furthermore, with the advent of various mobile operating systems supporting touch operation, integration of touch panels within the LCD and/or OLED display assembly of portable information handling systems has become highly relevant to satisfying market expectations. 
     Simultaneously, advancements in packaging design have reduced both the weight and thickness of LCD assemblies used in portable information handling systems. In particular, as the thickness of portable LCD assemblies with integrated touch functionality decreases, achieving sufficient structural integrity becomes more and more challenging. Risks of insufficient structural integrity in a thin or an ultra-thin LCD/touch assembly include excessive deflection that can lead to cracking of surface glass and/or disablement of touch functionality. 
     Accordingly, it is desirable to have an improved design and a correspondingly improved manufacturing method for ultra-thin LCD/touch assemblies for portable information handling systems that provide sufficient structural integrity for reliable operation and use. 
     SUMMARY 
     In one aspect, a disclosed method of manufacturing a display assembly for a portable information handling system may include edge bonding a laminate cover to a rear surface of a liquid crystal display (LCD) module. The laminate cover may be fiber-strengthened. The laminate cover may form an external surface of the portable information handling system. The method may include direct bonding a front surface of the LCD module to a cover glass using an optically clear adhesive having a thickness E to form the display assembly. The cover glass may include a transparent conductive electrode layer. 
     In another aspect, a disclosed method of manufacturing a cover glass for the display assembly may include machining a cover glass portion to form a cover glass. The cover glass portion may be cut from a glass sheet. The method may include performing a chemical edge polish to chemically smooth edges of the cover glass, depositing an edge polymer to edge surfaces of the cover glass, and bonding a transparent conductive layer supporting touch functionality to the cover glass. In various embodiments, the method may include depositing a conductive polymer layer over the transparent conductive layer at the edges of the cover glass, and applying a smart polymer layer at the edges of the cover glass, wherein the smart polymer hardens under mechanical loading. 
     Other disclosed aspects include the display assembly and a portable information handling system including the display assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention and its features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram of selected elements of an embodiment of a portable information handling system; 
         FIGS. 2A and 2B  are block diagrams of selected elements of an embodiment of an ultra-thin display including touch functionality; 
         FIG. 3  is flowchart depicting selected elements of an embodiment of a method for manufacturing an ultra-thin display assembly including touch functionality; and 
         FIG. 4  is flowchart depicting selected elements of an embodiment of a method for manufacturing a cover glass for use in an ultra-thin display assembly including touch functionality. 
     
    
    
     DESCRIPTION OF PARTICULAR EMBODIMENT(S) 
     In the following description, details are set forth by way of example to facilitate discussion of the disclosed subject matter. It should be apparent to a person of ordinary skill in the field, however, that the disclosed embodiments are exemplary and not exhaustive of all possible embodiments. 
     For the purposes of this disclosure, an information handling system may include an instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize various forms of information, intelligence, or data for business, scientific, control, entertainment, or other purposes. For example, an information handling system may be a personal computer, a PDA, a consumer electronic device, a network storage device, or another suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include memory, one or more processing resources such as a central processing unit (CPU) or hardware or software control logic. Additional components or the information handling system may include one or more storage devices, one or more communications ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communication between the various hardware components. 
     For the purposes of this disclosure, computer-readable media may include an instrumentality or aggregation of instrumentalities that may retain data and/or instructions for a period of time. Computer-readable media may include, without limitation, storage media such as a direct access storage device (e.g., a hard disk drive or floppy disk), a sequential access storage device (e.g., a tape disk drive), compact disk, CD-ROM, DVD, random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and/or flash memory (SSD); as well as communications media such wires, optical fibers, microwaves, radio waves, and other electromagnetic and/or optical carriers; and/or any combination of the foregoing. 
     As noted previously, current portable information handling systems may demand ever thinner solutions for LCD/touch assemblies (referred to herein as simply as a “display assembly”). However, as thickness of display assemblies becomes smaller, structural integrity becomes an ever more important issue. As will be described in further detail, the inventors of the present disclosure have developed novel methods and structures disclosed herein for manufacturing ultra-thin display assemblies for use in portable information handling systems. Although the present disclosure will be described using an LCD assembly, it is noted that an OLED display assembly may be used in various embodiments (not shown). 
     Particular embodiments are best understood by reference to  FIGS. 1, 2A, 2B, 3, and 4  wherein like numbers are used to indicate like and corresponding parts. 
     Turning now to the drawings,  FIG. 1  illustrates a block diagram depicting selected elements of an embodiment of portable information handling system  100 . As shown in  FIG. 1 , components of portable information handling system  100  may include, but are not limited to, processor subsystem  120 , which may comprise one or more processors, and system bus  121  that communicatively couples various system components to processor subsystem  120  including, for example, a memory subsystem  130 , an I/O subsystem  140 , local storage resource  150 , and a network interface  160 . System bus  121  may represent a variety of suitable types of bus structures, e.g., a memory bus, a peripheral bus, or a local bus using various bus architectures in selected embodiments. For example, such architectures may include, but are not limited to, Micro Channel Architecture (MCA) bus, Industry Standard Architecture (ISA) bus, Enhanced ISA (EISA) bus, Peripheral Component Interconnect (PCI) bus, PCI-Express bus, HyperTransport (HT) bus, and Video Electronics Standards Association (VESA) local bus. 
     In  FIG. 1 , network interface  160  may be a suitable system, apparatus, or device operable to serve as an interface between information handling system  100  and a network  155 . Network interface  160  may enable information handling system  100  to communicate over network  155  using a suitable transmission protocol and/or standard, including, but not limited to, transmission protocols and/or standards enumerated below with respect to the discussion of network  155 . In some embodiments, network interface  160  may be communicatively coupled via network  155  to network storage resource  170 . Network  155  may be implemented as, or may be a part of, a storage area network (SAN), personal area network (PAN), local area network (LAN), a metropolitan area network (MAN), a wide area network (WAN), a wireless local area network (WLAN), a virtual private network (VPN), an intranet, the Internet or another appropriate architecture or system that facilitates the communication of signals, data and/or messages (generally referred to as data). Network  155  may transmit data using a desired storage and/or communication protocol, including, but not limited to, Fibre Channel, Frame Relay, Asynchronous Transfer Mode (ATM), Internet protocol (IP), other packet-based protocol, small computer system interface (SCSI), Internet SCSI (iSCSI), Serial Attached SCSI (SAS) or another transport that operates with the SCSI protocol, advanced technology attachment (ATA), serial ATA (SATA), advanced technology attachment packet interface (ATAPI), serial storage architecture (SSA), integrated drive electronics (IDE), and/or any combination thereof. Network  155  and its various components may be implemented using hardware, software, or any combination thereof. 
     As depicted in  FIG. 1 , processor subsystem  120  may comprise a system, device, or apparatus operable to interpret and/or execute program instructions and/or process data, and may include a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or another digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, processor subsystem  120  may interpret and/or execute program instructions and/or process data stored locally (e.g., in memory subsystem  130  and/or another component of physical hardware  102 ). In the same or alternative embodiments, processor subsystem  120  may interpret and/or execute program instructions and/or process data stored remotely (e.g., in network storage resource  170 ). 
     Also in  FIG. 1 , memory subsystem  130  may comprise a system, device, or apparatus operable to retain and/or retrieve program instructions and/or data for a period of time (e.g., computer-readable media). Memory subsystem  130  may comprise random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a PCMCIA card, flash memory, magnetic storage, opto-magnetic storage, and/or a suitable selection and/or array of volatile or non-volatile memory that retains data after power to its associated information handling system, such as system  100 , is powered down. Local storage resource  150  may comprise computer-readable media (e.g., hard disk drive, floppy disk drive, CD-ROM, and/or other type of rotating storage media, flash memory, EEPROM, and/or another type of solid state storage media) and may be generally operable to store instructions and/or data. Likewise, network storage resource  170  may comprise computer-readable media (e.g., hard disk drive, floppy disk drive, CD-ROM, and/or other type of rotating storage media, flash memory, EEPROM, and/or other type of solid state storage media) and may be generally operable to store instructions and/or data. In system  100 , I/O subsystem  140  may comprise a system, device, or apparatus generally operable to receive and/or transmit data to/from/within system  100 . I/O subsystem  140  may represent, for example, a variety of communication interfaces, graphics interfaces, video interfaces, user input interfaces, and/or peripheral interfaces. As shown, I/O subsystem  140  may comprise touch panel  142  and display adapter  144 . Touch panel  142  may include circuitry for enabling touch functionality in conjunction with a display for (not shown) that is driven by display adapter  144 . 
     Turning now to  FIG. 2A , a block diagram of selected elements of an embodiment of display  200  is illustrated. In  FIG. 2A , display  200  is shown as a sectional view of an upper portion of a display included with portable information handling system  201 , which may be any of various types of portable information handling systems, as disclosed herein. As shown in  FIG. 2A , display  200  includes plastic frame  210 , structural element  212 , back cover  216 , wire connector  214  and display assembly  250  (see also  FIG. 2B ). Plastic frame  210  may represent a bezel or similar structure for framing display  200 , while structural element  212  may be a supporting member of display  200  that is comprised of a metal or metal allow, such as aluminum or an aluminum alloy. Back cover  216  may represent an external portion of information handling system  201 , while wire connector  214  may provide stability for internal circuitry and corresponding connectors. 
     Also shown in  FIG. 2A  is display assembly  250 , which will now be described in further detail (see also  FIG. 2B ). As shown display assembly  250  may represent a bonded structure of different elements that provides display and touch functionality within information handling system  201 . In particular embodiments, display assembly  250  may be an ultra-thin structure with high structural integrity and low deflection, as will be described herein. Display assembly  250  may include laminate cover  202 , foil layer  204 , tolerance gap  205 , LCD module comprising backlight portion  206  and display portion  207 , optically clear adhesive  208 , cover glass  209 . 
     In  FIG. 2A , laminate cover  202  may be formed using a multi-layered structure that has been fiber-strengthened. For example, when information handling system  201  is a laptop- or notebook-type of system, laminate cover  202  may be formed using carbon fiber laminate for strength and desirable exterior finish. In another non-limiting example, when information handling system  201  is a tablet-type of system, laminate cover  201  may be formed using aramid fiber and/or glass fiber laminate. In various embodiments, laminate cover  201  may be comprised of about 3 laminate layers. Foil layer  204  may be bonded to laminate cover  202  and may provide shielding against electromagnetic interference (EMI). In various embodiments, foil layer  204  may be a metallic layer that may be sprayed-on and/or deposited using a vacuum chamber process. Tolerance gap  205  may represent a gap between backlight portion  206  and laminate cover  202 , which may be edge bonded together. As used herein, “edge bonding” shall refer to a bonding process using adhesive at the edges of two members being bonded together, while “direct bonding” shall refer to a solid bond using an adhesive layer over surfaces of the two members being bonded together. An LCD module is shown as two portions, namely backlight portion  206  and display portion  207 . In some embodiments, the LCD module may be introduced into display assembly  250  after backlight portion  206  and display portion  207  are edge bonded together. In other embodiments, backlight portion  206  may first be edge bonded to laminate cover  202  and then edge bonded to display portion  207  (see also  FIG. 3 ). Display portion  207  is oriented for viewing facing cover glass  209 , and these two elements may be direct bonded together using optically clear adhesive  208 . As shown, cover glass  209  may include (or may be formed with, see  FIG. 4 ) transparent conductive electrode layer  218  bonded thereon to support touch functionality. In one embodiment, transparent conductive electrode layer  218  is a patterned layer of indium tin oxide (ITO) having an amorphous structure. Transparent conductive electrode layer  218  may be about 500 nm to 1000 nm thick, and/or may be as thick as transparency of the material selected for the layer permits for a given application. In different embodiments, other conductive oxide layers may be used for transparent conductive electrode layer  218 , such as, but not limited to, indium gallium tin oxide and indium zinc oxide, and may exhibit amorphous or crystalline structures. 
     As shown, display  200  may be very thin (i.e., between about 4.5 mm and 5.0 mm) in aggregate while exhibiting excellent structural integrity due to the novel structure of display assembly  250 , as described herein. Specifically, display assembly  250  may have a stiffness (or rigidity) such that when loaded with a force of 98 N (i.e., 22 lbs.) at a center of display assembly  250 , a deflection of the display assembly may be less than about 1% of a maximum span of the display assembly. The maximum span refers to a maximum of the width and the height of the display assembly. For example, when display assembly is 200 mm×300 mm, a deflection from a 22 lb. load at a center of display  200  may be less than about 3 mm. 
     Turning now to  FIG. 2B , a block diagram of selected elements of an embodiment of display assembly  250  is illustrated, representing the corresponding structure in  FIG. 2A . In  FIG. 2B , dimensional values are indicated for the elements included in display assembly. Laminate cover  202  may have a thickness A, where A is nominally about 0.8 mm, but may be in the range of about 0.4 mm to about 1.0 mm in different embodiments. Foil layer  204  may have a thickness B, where B is nominally about 0.15 mm. Tolerance gap  205  may have a thickness C, where C is nominally about 0.2 mm. LCD module, comprising backlight portion  206  and display portion  207 , may have an aggregate thickness D, where D is nominally about 2.4 mm, and may be as small as 2.0 mm in given embodiments. Optically clear adhesive  208  may have a thickness E, where E is nominally about 0.3 mm. Finally, cover glass  209  may have an aggregate thickness (including transparent conductive electrode layer  218  for supporting touch functionality, not shown in  FIG. 2B , see  FIG. 2A ) F, where F is nominally about 0.7 mm, and may be as small as 0.3 mm in given embodiments. A total thickness P of display assembly  250  (and/or of display  200 ) may be given by a sum of A, B, C, D, E, and F. According to the thickness values A-F described above, certain dimensional characteristics of display assembly  250  may be expressed as ratios and/or ranges of ratios. Specifically, a ratio of P/A may be selected in a range of about 10.4 to 4.4. A ratio of P/D may be selected in the range of about 2.2 to 1.7. A ratio of P/F may be selected in the range of about 14.5 and 5.9. 
     Referring now to  FIG. 3 , a block diagram of selected elements of an embodiment of method  300  for manufacturing an ultra-thin display assembly is depicted in flowchart form. It is noted that certain operations described in method  300  may be optional or may be rearranged in different embodiments. 
     In  FIG. 3 , method  300  may begin by edge bonding (operation  302 ) a fiber-strengthened laminate cover to a rear surface of a backlight portion of an LCD module. The rear surface of the backlight portion represents a surface opposing a display portion of the LCD module. The backlight portion may be edge bonded (operation  304 ) to a display portion of the LCD module. The backlight portion may be edge bonded at a front surface to the display portion. It is noted that, in certain embodiments, operation  304  may be omitted, for example, when the LCD module is used in method  300  after the backlight portion and the display portion have already been edge bonded together. Then, a front surface of the display portion may be direct bonded (operation  306 ) to a cover glass using an optically clear adhesive, while the cover glass includes a transparent conductive electrode layer supporting touch functionality on the cover glass. Finally, a display frame may be bonded (operation  308 ) to the cover glass. It is noted that the bonding in operation  308  may be performed on a rear surface of cover glass at a portion of cover glass that extends beyond a maximum span of the LCD module. 
     Referring now to  FIG. 4 , a block diagram of selected elements of an embodiment of method  400  for manufacturing a cover glass for using with the ultra-thin display assembly described herein is depicted in flowchart form. It is noted that certain operations described in method  400  may be optional or may be rearranged in different embodiments. 
     In method  400 , a large glass sheet may be cut (operation  402 ) to obtain an individually sized cover glass portion. The cover glass portion may be machined (operation  404 ) to a desired shape and holes may be drilled (operation  404 ), when present, to form a cover glass. Then, a chemical edge polish may be performed (operation  406 ) to smooth edges of the cover glass. An edge polymer may be deposited (operation  408 ) to edge surfaces of the cover glass. The edge polymer may be a microcrack-filling resin that stabilizes cracks in the cover glass. A transparent conductive electrode layer may be bonded (operation  410 ) on the cover glass to support touch functionality. In certain embodiments, operation  410  may involve a deposition process. The transparent conductive electrode layer may comprise indium tin oxide (ITO) and/or a similar transparent conductor. A conductive polymer layer may be deposited (operation  412 ) over the transparent conductive electrode layer near the edge of the cover glass. The conductive polymer layer may be deposited in operation  412  over edges of the transparent conductive electrode layer. Finally, a smart polymer layer may be applied (operation  414 ) at the edges of the cover glass. Application of the smart polymer may involve dip coating or brushing on (i.e., painting) processes. 
     As disclosed herein, methods for manufacturing an ultra-thin display assembly with integrated touch functionality may include edge bonding a laminate layer to a backlight portion of an LCD module. A display portion of the LCD module may be direct bonded to a cover glass including a transparent conductive electrode layer. The cover glass may be manufactured from a large glass sheet and may have an edge polymer deposited on edges of the cover glass, a conductive polymer layer over the transparent conductive electrode layer, and a smart polymer at the edges of the cover glass. 
     The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.