Abstract:
An optically enhanced flat panel display system, including apparatuses and methods for assembling same, for displaying images generated by a computer or electronic device with increased luminance and reduced reflectance, and for receiving user input for a computer or electronic device via a touch screen portion thereof. The flat panel display system comprises a touch screen portion integrally incorporated with and forward of a display portion. The display system has only one front polarizer such that the touch screen and display portions are generally positioned rearward thereof. In exemplary embodiments, the touch screen portion employs resistive touch screen technology and the display portion employs liquid crystal display technology. By including only one front polarizer, attenuation of display image light is minimized and an increase in net luminance is achieved over other flat panel display systems.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the field of flat panel display systems and more specifically to liquid crystal displays employed in connection with touch screens. 
       BACKGROUND OF THE INVENTION 
       [0002]    Since their initial development, flat panel display systems with active matrix liquid crystal displays (“AMLCDs”) have become increasingly popular for the display of computer-generated data in residential, commercial, and military environments. To enable user interaction with the computers that generate such data, manufacturers have coupled AMLCDs with touch screens that allow users to select a displayed item or otherwise provide an input to the computers by merely touching a user-accessible front cover panel of the touch screens. 
         [0003]    For example, some flat panel display systems that are employed in the cockpits of certain military aircraft have AMLCDs equipped with touch screens based on infrared touch technology. Using such a flat panel display system, a pilot may select a displayed item or provide an input to an aircraft computer by simply touching a front cover panel of the infrared touch screen. Unfortunately, such flat panel display systems do not always perform well when direct sunlight impinges upon them as may happen during an aircraft&#39;s flight. Such flat panel display systems also tend to require complex hardware and/or software, making them more expensive to manufacture. Further, the infrared circuitry of such flat panel display systems must be packaged within the display&#39;s bezel, thereby preventing the display&#39;s active area from extending close to the outside edges of the display bezel. 
         [0004]    In an attempt to overcome some of these difficulties of flat panel display systems equipped with infrared touch screens, manufacturers have integrated AMLCDs in flat panel display systems with touch screens that utilize resistive technology to detect the existence and x-y locations of user inputs relative to the boundaries of the screens. In such flat panel display systems, a resistive touch screen is placed in front of the display system&#39;s AMLCD. Unfortunately, such flat panel display systems suffer from a loss of luminance due to excess light filtering caused by the presence of redundant polarizers in the AMLCDs and resistive touch screens. 
         [0005]    Therefore, there exists in the industry a need for a flat panel display system having a touch screen input device that addresses these and other problems or difficulties that exist now or in the future. 
       SUMMARY OF THE INVENTION 
       [0006]    Broadly described, the present invention comprises an optically enhanced flat panel display system, including apparatuses and methods, for displaying images generated by a computer or electronic device with increased luminance and reduced reflectance, and for receiving user input for a computer or electronic device via a touch screen portion thereof. More particularly, the present invention comprises a flat panel display system having a touch screen portion integrally incorporated with and forward of a display portion. The flat panel display system has only one front polarizer such that the touch screen and display portions are positioned rearward thereof. Because the flat panel display system of the present invention has only a single front polarizer, the display system&#39;s net luminance is improved over prior art devices having multiple front polarizers that tend to attenuate light passing therethrough. Also, such improvement in net luminance is achieved without reducing the display system&#39;s contrast or color performance. 
         [0007]    In the exemplary embodiments described herein, the touch screen and display portions are arranged in configurations in which they are either separated by an air gap or are secured in contact with one another. Advantageously, in those configurations where the touch screen and display portions are separated by an air gap, the replacement of a faulty touch screen portion or display portion may be performed with relative ease as the flat panel display systems may be readily disassembled and reassembled with a working touch screen or display portion. In the configuration in which the touch screen and display portions are secured in contact with no air gap therebetween, reflections are beneficially reduced as compared to the other configurations (or compared to prior art devices) and, hence, the visibility and clarity of the images displayed by the flat panel display system is less effected and reduced by sunlight impinging thereon. Additionally, due at least in part to the touch screen and display portions being secured in contact, the flat panel display system&#39;s resistance to image white out and to display damage from high z-axis vibration is improved. 
         [0008]    Generally, in the exemplary embodiments, the touch screen portion comprises a resistive touch screen subassembly and the display portion comprises an active matrix liquid crystal display subassembly. Because the touch screen portion utilizes resistive touch screen technology, there is no need to package touch screen circuitry in the display&#39;s bezel as with other technologies and, therefore, the display&#39;s active area may be extended nearer the outside edges of the display bezel. It should be noted that while the touch screen portion comprises a resistive touch screen subassembly and the display portion comprises an active matrix liquid crystal display subassembly in the exemplary embodiments described herein, the scope of the present invention is not limited to the use of touch screens employing resistive technology or to displays employing liquid crystal technology. 
         [0009]    Other advantages and benefits of the present invention will become apparent upon reading and understanding the present specification when taken in conjunction with the appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0010]      FIG. 1  is a side view of a flat panel display system in accordance with a first exemplary embodiment of the present invention. 
           [0011]      FIG. 2  is a side view of a flat panel display system in accordance with a second exemplary embodiment of the present invention. 
           [0012]      FIG. 3  is a side view of a flat panel display system in accordance with a third exemplary embodiment of the present invention. 
           [0013]      FIG. 4  is a side view of a flat panel display system in accordance with a fourth exemplary embodiment of the present invention. 
           [0014]      FIG. 5  is a side view of a flat panel display system in accordance with a fifth exemplary embodiment of the present invention. 
           [0015]      FIG. 6  is a pictorial representation of a method of light propagation through the flat panel display systems of the exemplary embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    Referring now to the drawings in which like numerals represent like elements or steps throughout the several views,  FIG. 1  displays a side view of a flat panel display system  100  in accordance with a first exemplary embodiment of the present invention. The flat panel display system  100  comprises a single front polarizer  102 , a resistive touch screen portion  104 , an AMLCD portion  106 , a single rear polarizer  108 , and an AMLCD heater portion  110  that are arranged as layers in a substantially sandwich-like structure. The flat panel display system  100  has a front  112  and back  114  with the front polarizer  102 , the resistive touch screen portion  104 , the AMLCD portion  106 , the rear polarizer  108 , and the AMLCD heater portion  110  being sequentially and substantially adjacently arranged between the display system&#39;s front  112  and back  114 . The flat panel display system  100  is adapted to receive light, during operation, from a light source (not shown) that is located proximate the back  114  thereof. The light, referred to herein as “back light”, is directed at the display system&#39;s back  114  and in a direction toward the display system&#39;s front  112  so as to provide light that is transmitted, as appropriate, by the AMLCD portion  106  to define the images (also, perhaps, referred to herein as “display image light”) being displayed by the display system  100 . 
         [0017]    The front polarizer  102 , generally, has anti-reflective and hard coatings on its surfaces and comprises the only front polarizer of the flat panel display system  100 . The front polarizer  102  is, typically, bonded to the front surface of the resistive touch screen portion&#39;s first quarter wave plate  118  (described below). Such bonding (as are other bonding operations identified herein) is performed using conventional techniques that should be known to one of ordinary skill in the art. The front surface of the front polarizer  102  is, in most installations of the flat panel display system  100 , accessible to users and is configured to be slightly deflected, or flexed, by such users when they attempt to select displayed items or provide input to a computer communicatively connected to the flat panel display system  100  by applying pressure to the front surface with a finger, stylus, or other selection or pointing device. The front polarizer&#39;s hard coating aids in protecting the front polarizer  102  (and, for that matter, the flat panel display system  100 ) from damage due to outside sources and the anti-reflective coating enables the front polarizer  102  to block reflected light. 
         [0018]    The resistive touch screen portion  104  (also, perhaps, referred to herein as the “resistive touch screen subassembly  104 ”) of the flat panel display system  100  is adapted to receive, during use, a selection of a item displayed by the AMLCD portion  106  or other input provided by a user through the application of pressure to the display system  100  with a finger, stylus, or other selection or pointing device, and to produce a voltage division representative of the x-y location of the applied pressure to connected (via interface wires not shown) electrical circuitry in a manner similar to conventional resistive touch screen devices. The resistive touch screen portion  104  comprises opposed first and second quarter wave plates  118 ,  120  that are, generally, adapted to cancel glare and allow the passage of light therethrough with very minimal light absorption. The first quarter wave plate  118  is positioned adjacent to the front polarizer  102  and is, typically, bonded thereto. The first quarter wave plate  114  is more particularly adapted to convert linearly-polarized light received from the front polarizer  102  into circularly polarized light, to convert circularly-polarized reflected light into linearly-polarized light for absorption by the front polarizer  102 , and to convert circularly-polarized display image light for transmission by the front polarizer  102 . 
         [0019]    The second quarter wave plate  120  is positioned such that it is substantially opposed and parallel to the display system&#39;s AMLCD portion  106 , but separated therefrom by a first air gap  122 . According to the first exemplary embodiment, the first air gap  122  defines a distance, D 1 , between the resistive touch screen and AMLCD portions  104 ,  106  that has a measure of approximately 0.5 to 5.0 millimeters. It should be noted, however, that if vibration may be an issue in a particular implementation of the flat panel display system  100 , the first air gap  122  might be eliminated with the second quarter wave plate  120  being bonded directly to the front surface of the display system&#39;s AMLCD portion  106 . The second quarter wave plate  120  is adapted to convert circularly-polarized light incident thereon into linearly-polarized light, convert linearly-polarized reflected light into circularly-polarized light, and convert linearly-polarized display image light into circularly-polarized light. 
         [0020]    The resistive touch screen portion  104  further comprises an electromagnetic interference (EMI) shield  124 , a touch front glass  126 , a touch front resistance surface  128 , a touch rear resistive surface  130 , and a touch rear glass  132  positioned between the first and second quarter wave plates  118 ,  120 . The electromagnetic interference shield  124  is positioned adjacent to, and interposed between, the first quarter wave plate  118  and the touch front glass  126 . Typically, the electromagnetic interference shield  124  has an indium-tin oxide coating and is bonded to the first quarter wave plate  118  and the front surface of the touch front glass  126 . In order to minimize light absorption, the electromagnetic interference shield  124  has a refractive index that is, generally, matched with the first quarter wave plate  118  and the touch front glass  126 . When the flat panel display system  100  is in use, the electromagnetic interference shield  124  provides boundary protection against electromagnetic interference radiated emissions or susceptibility. 
         [0021]    The touch front glass  126  provides a substrate for the touch front resistive surface  128  (described below) and has, according to the first exemplary embodiment, a thickness in the front-to-back direction measuring approximately 0.2 millimeters. The thickness of the touch front glass  126  is selected so as to enable the touch front glass  126  to deflect or flex, when the flat panel display system  100  is in use and a displayed item is selected by a user, by an amount sufficient to cause the touch front resistive surface  128  and touch rear resistive surface  130  to come into contact. Thus, it should be noted that the touch front glass  126  might have different thicknesses in different implementations of the flat panel display system  100  as is necessary to enable sufficient deflection or flexing thereof. 
         [0022]    The touch rear glass  132  is positioned rearward of and substantially parallel to the touch front glass  126  such that the back surface of the touch rear glass  132  is adjacent to and secured to the front surface of the second quarter wave plate  120 . Generally, the touch rear glass  132  and second quarter wave plate  120  are bonded together. The touch rear glass  132  provides a substrate for the touch rear resistive surface  128  and has a thickness in the front-to-back direction that is selected so as to resist appreciable deflection, or flexing, during a user&#39;s selection of an item displayed by the flat panel display system  100 . According to the first exemplary embodiment, the touch rear glass  132  has a thickness of approximately 3 millimeters. It should be noted, however, that the thickness of the touch rear glass  132  might have other measures in other embodiments of the present invention. 
         [0023]    The touch front resistive surface  128  is applied and secured to the back surface of the touch front glass  126  such that the touch front resistive surface  128  deflects, or flexes, in substantial unison with the touch front glass  126  during a user&#39;s selection of an item displayed by the flat panel display system  100 . The touch rear resistive surface  130  is applied and secured to the front surface of the touch rear glass  132 , but due at least in part to the rigidity and thickness of the touch rear glass  132 , the deflection or flexing of the touch rear resistive surface  130  is limited and minimized during a user&#39;s selection of an item displayed by the flat panel display system  100 . Respectively, the touch front and rear resistive surfaces  128 ,  130  comprise front and rear resistive elements of the display system&#39;s resistive touch screen portion  104  that function in a manner that is substantially similar to resistive surfaces in common resistive touch screen devices. Typically, the touch front and rear resistive surfaces  128 ,  130  each have an indium-tin oxide coating. 
         [0024]    The resistive touch screen portion  104  further comprises a plurality of touch spacers  134  that are interposed between the touch front and rear resistive surfaces  128 ,  130 . The touch spacers  134  prevent the touch front resistive surface  128  and the touch rear resistive surface  130  from coming into contact absent deflection, or flexing, of the front polarizer  102 , first quarter wave plate  118 , electromagnetic interference shield  124 , and touch front glass  126 . Generally, the touch spacers  134  are manufactured from a material that is electrically non-conductive. 
         [0025]    The AMLCD portion  106  (also, perhaps, referred to herein as the “AMLCD subassembly  106 ” or the “display portion  106 ”) of the flat panel display system  100  is communicatively connectable to a computer system or other similar device through a conventional AMLCD interface (not shown) and is operable to selectively transmit and/or block back light through appropriate electrical energization/de-energization of a liquid crystal material therein in order to produce images (e.g., represented by display image light) visible to a user of the flat panel display system  100 . The AMLCD portion  106  of the flat panel display system  100  comprises first and second AMLCD glass panels  136 ,  138  that define a cell gap therebetween (not shown) in which the liquid crystal material resides. The first AMLCD glass panel  136  is oriented substantially parallel to the second AMLCD glass panel  138 , the second quarter wave plate  118 , and the rear polarizer  108 . Generally, the first and second AMLCD glass panels  136 ,  138  comprise AMLCD glass panels found in conventional AMLCD displays. The front surface of the first AMLCD glass panel  136  has an anti-reflective coating  140  applied thereto. The anti-reflective coating  140  and the second quarter wave plate  118  define first air gap  122  therebetween. The rear polarizer  108  is oriented adjacent to the second AMLCD glass panel  138  with the rear polarizer&#39;s front surface being secured to the back surface of the second AMLCD glass panel  138 , generally, by bonding. The rear polarizer  108  has an anti-reflective coating to reduce light reflection. 
         [0026]    The AMLCD heater portion  110  (also, perhaps, referred to herein as the “AMLCD heater subassembly  110 ” or “display heater  110 ”) is configured to warm the AMLCD portion  106  of the flat panel display system  100 . Such warming is necessary to eliminate sluggish response of the liquid crystal material. The AMLCD heater portion  110  is positioned substantially parallel to and rearward of the display system&#39;s rear polarizer  108  and defines a second gap  142  with the rear polarizer  108 . The second gap  142 , in accordance with the first exemplary embodiment, defines a distance, D 2 , between the AMLCD heater portion  110  and rear polarizer  108  that has a measure of approximately 0.5 to 5.0 millimeters. It should be noted, however, that if vibration may be an issue in a particular implementation of the flat panel display system  100 , the second air gap  142  may be eliminated with the AMLCD heater portion  110  being bonded directly to the back surface of the display system&#39;s rear polarizer  108 . 
         [0027]    The AMLCD heater portion  110  comprises a resistive heater element  144  that is configured to supply heat, across second gap  142 , to the rear polarizer  108  and, hence, to the second AMLCD glass panel  138 . The liquid crystal material is warmed through its contact with the second AMLCD glass panel  138 . The resistive heater element  144  has refractive index that is, generally, matched with the heater glass  146  to minimize light absorption. The resistive heater element  144  also, typically, has an indium-tin oxide coating. 
         [0028]    The AMLCD heater portion  110  further comprises a heater glass  146  located rearwardly adjacent to and in contact with the resistive heater element  144 . The heater glass  146  provides a substrate for the resistive heater element  144  such that the resistive heater element  144  is, generally, bonded to the heater glass  146 . The heater glass  146  also serves to add rigidity and stiffening to the flat panel display system  100 . 
         [0029]      FIG. 2  displays a side view of a flat panel display system  100 ′ in accordance with a second exemplary embodiment of the present invention. The flat panel display system  100 ′ is substantially similar in structure and operation to the flat panel display system  100  of the first exemplary embodiment, albeit with a few differences. For example, in the flat panel display system  100 ′ of the second exemplary embodiment, there is no air gap between the AMLCD and AMLCD heater portions  106 ′,  110 ′. The AMLCD heater portion  110 ′ is secured (generally, by bonding) directly to the AMLCD portion  106 ′. Also, in the flat panel display system  100 ′ of the second exemplary embodiment, the resistive heater element  144 ′ is positioned rearwardly adjacent to and in contact with the rear surface of the heater glass  146 ′ such that the front surface of the heater glass  146 ′ is immediately adjacent to and in contact with the back surface of the rear polarizer  108 ′. Typically, the front surface of the heater glass  146 ′ is bonded to the back surface of the rear polarizer  108 ′. In such an arrangement, the heater glass  146 ′ acts as a stiffener to improve the rigidity of the AMLCD portion  106 ′. 
         [0030]      FIG. 3  displays a side view of a flat panel display system  100 ″, according to a third exemplary embodiment of the present invention, which may be employed when a particular application requires a relatively large flat panel display. The flat panel display system  100 ″ is substantially similar in structure and operation to the flat panel display system  100  of the first exemplary embodiment with some differences. For example, in the flat panel display system  100 ″ of the third exemplary embodiment, there is no air gap between the resistive touch screen portion  104 ′ and the AMLCD portion  106 ′. The resistive touch screen portion  104 ′ is secured (generally, by bonding) directly to the AMLCD portion  106 ′. Also, in the flat panel display system  100 ″ of the third exemplary embodiment, the front surface of the first AMLCD glass panel  136 ′ has no anti-reflective coating. As a consequence, the front surface of the first AMLCD glass panel  136 ′ is immediately adjacent to and in contact with the back surface of the second quarter wave plate  120 ′. Typically, the front surface of the first AMLCD glass panel  136 ′ is bonded to the back surface of the second quarter wave plate  120 ′. 
         [0031]      FIG. 4  displays a side view of a flat panel display system  100 ′″ in accordance with a fourth exemplary embodiment of the present invention. The flat panel display system  100 ′″ is substantially similar in structure and operation to the flat panel display system  100 ″ of the third exemplary embodiment. However, the flat panel display system  100 ′″ of the fourth exemplary embodiment differs from that of the third exemplary embodiment in a few important respects. For example, in the flat panel display system  100 ′″ of the fourth exemplary embodiment, there is no AMLCD heater portion or heater element and the rear polarizer  108 ′″ has an anti-reflective coating. As a consequence, the flat panel display system  100 ′″ of the fourth exemplary embodiment is generally employed in those applications in which it is not necessary to heat the liquid crystal of the AMLCD portion  106 ′″ thereof. 
         [0032]      FIG. 5  displays a side view of a flat panel display system  100 ″″, in accordance with a fifth exemplary embodiment of the present invention, that may also be employed in applications in which it is not necessary to heat the liquid crystal of the AMLCD portion  106 ′″ thereof. The flat panel display system  100 ″″ is substantially similar in structure and operation to the flat panel display system  100 ′ of the second exemplary embodiment except that, in the flat panel display system  100 ″″ of the fifth exemplary embodiment, there is no AMLCD heater portion or heater element and there is no rear polarizer. 
         [0033]      FIG. 6  displays a pictorial representation of a method of light propagation through the flat panel display systems  100  of the exemplary embodiments of the present invention in which common light streams are commonly numbered and changes in associated alpha letters are used to designate changes in the polarization states of the light streams. As illustrated in  FIG. 6 , light  150 A from a non-polarized source (not shown) impinges upon the front surface of the front polarizer  102  of a flat panel display system  100 . The polarization of the light  150 A is modified as it travels through the front polarizer  102  such that it exits the front polarizer  102  as light  150 B linearly polarized in a vertical direction. 
         [0034]    The exiting light  150 B then impinges upon the front surface of the first quarter wave plate  118 . The impinging light  150 B passes through and exits the first quarter wave plate  118  as circularly polarized light  150 C. After exiting the first quarter wave plate  118 , the circularly polarized light  150 C then passes through the electromagnetic interference shield  124 , touch front glass  126 , and touch rear glass  132  with its polarization substantially unchanged. The circularly polarized light  150 C subsequently impinges on the front surface of the second quarter wave plate  120  with a first portion of it passing therethrough and a second portion being reflected. During passage of the first portion through the second quarter wave plate  120 , the polarization of such impinging light  150 C is altered so that it exits the second quarter wave plate  120  as impinging light  150 D linearly polarized in a horizontal direction. The exiting light  150 D next impinges on the front surface of the first AMLCD glass panel  136  of the display system&#39;s AMLCD portion  106  as described below. 
         [0035]    The second, or reflected, portion of impinging light  150 C is, as noted above, reflected by the front surface of the second quarter wave plate  120  as reflected light  154 A and is circularly polarized in the angular direction opposite that of impinging light  150 C. The reflected light  154 A travels in a substantially opposite direction to impinging light  150 C and impinges on and passes through touch rear resistive surface  130  and touch rear glass  132 . Upon exiting, reflected light  154 A propagates toward electromagnetic interference shield  124  and touch front glass  126 . Reflected light  154 A passes therethrough substantially unchanged and then impinges on the rear surface of first quarter wave plate  118 . While passing through first quarter wave plate  118 , the polarization of reflected light  154 A is changed such that it exits the first quarter wave plate  118  and impinges on the rear surface of front polarizer  102  as reflected light  154 B linearly polarized in the horizontal direction. Then, due at least in part to the horizontal polarization of reflected light  154 B, front polarizer  102  absorbs most of reflected light  154 B, thereby substantially blocking its further transmission to the environment around the flat panel display system  100 . 
         [0036]    As described above, impinging light  150 D strikes the front surface of the first AMLCD glass panel  136  of the display system&#39;s AMLCD portion  106 . Upon striking the first AMLCD glass panel  136 , the impinging light  150 D is reflected as reflected light  150 E polarized with at least some change in the polarization state or axis (shown here as the extreme case of ninety degree (90°) rotation of the polarization state or axis). The reflected light  150 E then impinges on the back surface of the second quarter wave plate  120 , passes therethrough, and exits the second quarter wave plate  120  as reflected light  150 F with its polarization changed to circular polarization. Next, the reflected light  150 F travels through the touch rear glass  132 , touch front glass  126 , and electromagnetic interference shield  124  with its polarization substantially unchanged before impinging on the back surface of first quarter wave plate  118 . The reflected light  150 F passes through the first quarter wave plate  118  where its polarization is modified so that it exits the first quarter wave plate  118  as reflected light  150 G that is linearly polarized in a horizontal direction. After exiting the first quarter wave plate  118 , the reflected light  150 G impinges on the front polarizer  102  where at least some of it is absorbed and not transmitted further. 
         [0037]    As also illustrated in  FIG. 6 , non-polarized back light  152 A is directed at the back surface of the rear polarizer  108  from a back light source (not shown) to provide light that is ultimately selectively transmitted and/or blocked by the AMLCD portion  106 . The non-polarized back light  152 A passes through the rear polarizer  108  and exits as back light  152 B polarized in a vertical direction. The back light  152 B then impinges on the back surface of the second AMLCD glass panel  138  of the display system&#39;s AMLCD portion  106 . While passing through the AMLCD portion  106 , the polarization of the transmitted portion of the back light  152 B is changed such that the back light  152 C exiting the display system&#39;s AMLCD portion  106  is either vertically or horizontally polarized, depending on the “on” or “off” (e.g., “white” or “black”) state of the pixel intercepted by the back light  152 B. The exiting back light  152 C then travels through the second quarter wave plate  120  where it is converted to circularly polarized back light  152 D. It then passes through the touch rear glass  132 , touch front glass  126 , and electromagnetic interference shield  124  with its polarization substantially unchanged. 
         [0038]    After exiting the electromagnetic interference shield  124 , the back light  152 D impinges upon the back surface of the first quarter wave plate  118  and passes therethrough. The polarization of the back light  152 D is altered by the first quarter wave plate  118  so that the back light  152 E exiting the first quarter wave plate  118  is linearly polarized in a horizontal or vertical direction, depending on whether the intercepted pixel was “off” or “on” (e.g., “black” or “white”). The back light  152 E subsequently impinges on the front polarizer  102  and is either absorbed (e.g., “off” or “black” state) by the front polarizer  102  or transmitted (e.g., “on” or “white” state) by the front polarizer  102  to the environment around the flat panel display system  100  absent further substantial change to its polarization. 
         [0039]    It should be understood that although the flat panel display system  100  of the present invention has been described via the above exemplary embodiments using particular types of polarizers and quarter wave plates and particular orientations and phase angles of the polarization axes (e.g., vertical and horizontal), the scope of the present invention is not limited to such polarizers, quarter wave plates, orientations, and phase angles. Therefore, the scope of the present invention includes other embodiments that may utilize the same or different types of polarizers, quarter wave plates, orientations, and/or phase angles in the same or different combinations and/or relative positions. Further, it should be understood that the scope of the present invention includes other embodiments of the flat panel display system  100  that have or do not have an AMLCD heater portion or heater element. 
         [0040]    Whereas this invention has been described in detail with particular reference to exemplary embodiments and variations thereof, it is understood that other variations and modifications can be effected within the scope and spirit of the invention, as described herein before and as defined in the appended claims.