Abstract:
A touchscreen ( 126 ) for assembly onto a liquid crystal display module ( 119 ) in a wireless communication device ( 103 ). The touchscreen is comprised of a front laminant pet film ( 127 ), a chemically strengthened glass panel ( 129 ), an optically clear acrylic adhesive ( 131 ) and a rear laminant pet film ( 133 ). The rear laminant pet film ( 133 ) greatly increases the strength and durability of the touchscreen ( 126 ) and eliminates the need for a protective lens over the display module of the wireless communication device ( 103 ).

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of wireless communication, and more particularly to a personal radio transceiver. Although, the invention is subject to a wide range of applications, it is especially suited for use in a handheld radiotelephone, and will be particularly described in that connection. 
     BACKGROUND OF THE INVENTION 
     Liquid crystal displays incorporating touchscreens for use in a radiotelephone are known in the art. These touchscreens typically include four layers, a front laminant (pet film) layer, a circuitry layer having a flex tail for connection to a microprocessor in the radiotelephone, an adhesive layer and a glass panel that shows the active and viewing area of the touchscreen. Among other things, the front laminant serves as a protective covering for the glass layer. However, when the radiotelephone is not in use, additional protective covering for the touchscreen is needed because the front laminant is not strong enough to protect the glass layer from breaking or cracking in the event that the telephone is dropped or otherwise abused. This additional protective covering increases the size and expense of the phone. 
     Accordingly, there is a need for a touchscreen that can be used with a liquid crystal display module without a protective cover to prevent the assembly from breaking or cracking when the radiotelephone is dropped or otherwise abused. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a radio communication system in which the preferred embodiment of the touchscreen of the present invention can be implemented. 
     FIG. 2 is a detailed illustration of the preferred embodiment of the touchscreen of the present invention that can be used with the display module shown in FIG.  1 . 
    
    
     SUMMARY OF THE PREFERRED EMBODIMENT 
     The present invention provides a durable touchscreen and method for making the same that can be used with a display module in a wireless communication device such as a radiotelephone. In the presently preferred embodiment, the touchscreen includes a front laminant; a circuitry layer having a flex tail; a first adhesive layer applied to the underside of the circuitry layer; a glass panel having a top surface and a bottom surface, the top surface applied to the first adhesive layer; a second adhesive layer applied to the bottom surface of the glass panel; and a rear laminant applied to the second adhesive layer such that the glass panel and the rear laminant are coupled together. The rear laminant greatly increases the strength of the touchscreen, thereby eliminating the need for a protective lens to prevent the touchscreen from breaking or cracking when it is dropped. The elimination of the protective lens reduces the volume and weight of the radiotelephone and optimizes the look and feel of the product. 
     Additional advantages and novel features of the invention will be set forth in part in the description which follows, wherein the preferred embodiment of the invention is shown and described. Reference will now be made in detail to an embodiment configured according to the present invention. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment of the present invention preferably includes a radio communication device  103  having a touch screen  126  disposed in the body housing element  107  for displaying functional icons associated with particular communication services such as telephone, e-mail, fax, short messaging service or other service. The functional icons displayed on the screen can be accessed by touching the screen with a stylus or writing implement. 
     FIG. 1 is a block diagram of a radio communication system  100 . The radio communication system  100  includes a remote transceiver  101  for sending and receiving radio frequency (RF) signals to and from multiple radio communication devices within a fixed geographic area. The radio communication device  103  is one such radio communication device contained within the geographic area served by the remote transceiver  101 . The RF signals transmitted between the remote transceiver  101  and the radio communication device  103  provide radio communication services such as radiotelephone service, electronic mail service, wireless fax service and short message service. Other embodiments of the present invention may include other combinations of these communication services and other radio communication services. 
     The radio communication device  103  includes an antenna  105  and a body housing element  107 . In the preferred embodiment, the body housing element  107  includes radio circuitry  113 , a processor  115 , and a portion of a user interface  117 . The user interface  117  includes a display module  119 , a touchscreen  126 , a microphone  121 , a speaker  123 , and a keypad  125 . 
     The radio communication device  103  receives the RF signals through the antenna  105  and converts the received RF signals into electrical RF signals for use by the radio circuitry  113 . The radio circuitry  113  demodulates the electrical RF signals and recovers the data transmitted using the RF signals. Additionally, the radio circuitry  113  outputs the data to the processor  115 . The processor  115  includes at least a main microprocessor such as an MC68040 available from Motorola, Inc., and associated memory as well as other control circuits including integrated circuits or other known technologies. The processor  115  formats the data output from the radio circuitry  113  into a recognizable voice or messaging information for use by the user interface  117 . The user interface  117  communicates the received information or voice to a user through the use of the speaker  123  and the touchscreen  126  used with the display module  119 . 
     Upon transmission of RF signals from the radio communication device  103  to the remote transceiver  101 , the user interface  117  transmits user input data to the processor  115 . Such data may include voice data and/or messaging information. The processor  115  formats the information obtained from the user interface  117  and transmits the formatted information to the radio circuitry  113 . The radio circuitry  113  converts the formatted information into electrical RF modulated signals to the antenna  105  for transmission back to the remote transceiver  101   
     FIG. 2 is a detailed illustration of the touchscreen  126  shown in FIG.  1 . In the presently preferred embodiment, touchscreen  126  includes six layers: a front laminant pet film  127  commercially available from GE Plastics, Pittsfield, Mass.; a circuitry layer  128 , preferably having a flex tail for connection to microprocessor  115  shown in FIG. 1; a first layer of adhesive  129 , preferably an optically clear acrylic adhesive commercially available from 3M Corporation, Rochester, Minn.; a glass panel  130 , preferably a chemically strengthened glass commercially available from PPG glass, Elgin, Ill.; a second layer of adhesive  131 , preferably the optically clear acrylic adhesive commercially available from 3M Corporation; and a rear laminant pet film  133  commercially available from GE Plastics. 
     In the preferred embodiment, the front laminant  127  is disposed on a top surface of the circuitry layer  128 . A top surface of the glass panel  130  is coupled to the underside of circuitry layer  128  using the first layer of adhesive  129 . Then, the rear laminant  133  is coupled to the bottom surface of the glass panel  130  using the second layer of adhesive  131 . Finally, the touchscreen is assembled on the front side of the LCD display module with adhesive. 
     Radiotelephones incorporating the preferred embodiment of the touchscreen  126  of the present invention were subjected to six (6) foot drop tests and ball bearing impact tests (“drop tests”) to ensure that the display module  119  and the touchscreen  126  can withstand being dropped or otherwise abused by a user without breaking or cracking. In addition, these tests were performed on the commonly used touchscreens that include only the first four layers (front laminant pet film  127 , circuitry layer  128 , adhesive  129  and glass panel  130 ) to show the impact of the back laminant  133  on the touchscreen  126 . The touchscreens  126  of the present invention survived the drop tests from a height fifty (50) percent higher than the height at which the conventional touchscreens consisting of only four layers survived. 
     The test results show that the touchscreen  126  of the present invention, which incorporates both a front laminant  127  and a rear laminant  133  surrounding the glass panel  129 , meets high requirements of durability and eliminates the need for an acrylic lens to protect the display  119 . Eliminating the protective lens allows the radio communication device  103  to utilize the touchscreen feature while reducing the device&#39;s  103  overall weight and volume, thereby optimizing the overall product for the customer. 
     Those skilled in the art will recognize that various modifications and variations can be made in the apparatus of the present invention and in construction of this apparatus without departing from the scope or spirit of this invention.