Abstract:
Repair or replacement of a transparency mounted in body of a vehicle, e.g. an aircraft when one or more properties of the transparency is (are) operating outside of an acceptable limit(s) is arranged by monitoring operating performance of a property of the transparency, e.g. by mounted a sensor, e.g. a sensor for detecting moisture; a sensor for detecting impacts and vibrations; a sensor for detecting fractures; a sensor for detecting electric arcing, and a sensor for measuring temperature of an electrically conductive coating, on the transparency. Scheduling repair or replacement of the transparency at a geographical area when the operating performance of the property is outside an acceptable operating performance limit, and forwarding the schedule to the vehicle and to a maintenance location to prepare for the repair or replacement of the transparency at the geographical work area.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is related to U.S. patent application Ser. No. ______ filed even date in the names of Ali Rashid, James Priddy and Monroe A. Stone and titled TRANSPARENCY HAVING SENSORS. U.S. patent application Ser. No. ______ in its entirety is hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a method of and a system for maintaining operating performance of a transparency, e.g. a vehicle window, and more particularly for timely and economically scheduling repair or replacement of the vehicle window, e.g. an aircraft windshield, when sensor of the windshield indicates that a property of the windshield is performing outside of an acceptable limit. 
         [0004]    2. Discussion of the Presently Available Transparency Technology 
         [0005]    Aircraft or aerospace windows, e.g. aircraft windshields include a laminate of plastic layers or sheets, glass layers or sheets and combinations thereof. The layers of an inner segment of the windshield face the interior of the aircraft and provide structural stability to the windshield. The outer segment of the windshield faces the exterior of the aircraft and usually includes a laminate of glass sheets. The outer segment of the windshield, which can also provide structural stability is usually provided with accessories for visual acuity. For example and not limiting to the discussion, the outer segment of the windshield can include an electrically conductive coating, or a plurality of electrically conductive wires, between and connected to a pair of spaced bus bars to heat the windshield to prevent the formation of, and/or remove fog and ice on and/or from, respectively, the outer surface of the windshield. 
         [0006]    As is appreciated by those skilled in the art, as the service time of the aircraft windshield increases, the operating efficiency of the windshield decreases until such time that the accessories of the windshield become non-functional, and the windshield needs to be replaced or repaired. More particularly, the peripheral edge of the windshield has an outboard moisture seal that is a barrier to prevent moisture from entering between the plastic and glass layers or sheets of the windshield. When the seal fails, e.g. cracks and/or the layers de-bond due to erosion caused by wind and rain, moisture enters between the layers of the windshield. While the cracking or de-bonding of the seal is not a structural issue, when moisture reaches inside the windshield, the windshield can de-laminate, and the conductive coating or wires, whichever is present can be damaged and fail, thereby reducing the service life of the windshield. More particularly, when delamination of the windshield occurs, increased amounts of moisture move between the layers of the windshield accelerating the degradation of the windshield, e.g. damage and/or failure of the bus bars and electrically conductive coating or wires reducing or eliminating the defrosting capabilities of the windshield. 
         [0007]    Untimely response to repair defects in the accessories of the transparency when they begin, decreases the operating efficiency of the transparency and can result in the need for emergency maintenance, e.g. transparency repair or replacement. It would be advantageous, therefore, to provide a transparency having sensors to monitor the performance of the transparency and a method of acting on the information from the sensors such that repairs, or replacements, of the transparencies is scheduled maintenance and not emergency maintenance. 
       SUMMARY OF THE INVENTION 
       [0008]    This invention relates to a method of arranging repair or replacement of a transparency when a property of the transparency is operating outside of an acceptable limit, wherein the transparency is mounted in body of a vehicle, the method includes monitoring operating performance of the property of the transparency; scheduling repair or replacement of the transparency at a geographical area when the operating performance of the property is outside an acceptable operating performance limit, and forwarding the schedule to the vehicle and to a maintenance location to prepare for the repair or replacement of the transparency at the designated geographical work area. 
         [0009]    The invention further relates to a system for arranging repair to, or replacement of, a transparency when a property of the transparency is operating outside of an acceptable limit, wherein the transparency is mounted in body of a vehicle. The system includes, among other things, a sensor to monitor operating performance of the property, and to generate a first signal providing the operating performance of the property, and data processing equipment to receive the information of the first signal, and to generate a second signal scheduling repair or replacement of the transparency at a geographical area when the operating performance as indicated by the first signal is outside an acceptable operating performance limit, wherein the second signal is forwarded to the vehicle and to a maintenance location to prepare for repair or replacement of the transparency. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0010]      FIG. 1  is a cross sectional view of a non-limiting embodiment of an aircraft windshield used in the practice of the invention. 
           [0011]      FIG. 2  is an isometric view of a non-limiting embodiment of a heating arrangement of the invention. 
           [0012]      FIG. 3  is a plan view of a non-limiting embodiment of impact sensors or detectors positioned on the electrically conductive member of a heating arrangement in accordance to the teachings of the invention. 
           [0013]      FIG. 4  is a non-limiting embodiment of an electrical system of the invention to monitor and act on output signals of the impact sensors shown in  FIG. 3  in accordance to the teachings of the invention. 
           [0014]      FIG. 5  is a schematic view of a non-limiting embodiment of a rupture sensor or detector of the invention. 
           [0015]      FIG. 6  is a view taken along lines  6 - 6  of  FIG. 5 . 
           [0016]      FIG. 7  is a plan view of another non-limiting embodiment of a rupture sensor or detector of the invention. 
           [0017]      FIG. 8  is a plan view of non-limiting embodiment of a sensor or detector to monitor the temperature of the electrically conductive member of a heating arrangement in accordance to the teachings of the invention. 
           [0018]      FIG. 9  is a non-limiting embodiment of an electrical system to monitor and act on the output signals of the sensor shown in  FIG. 8  in accordance to the teachings of the invention. 
           [0019]      FIG. 10  is a non-limiting embodiment of an electrical system of the invention for measuring the voltage output of a bus bar of the heating arrangement shown in  FIG. 8  to monitor the temperature of the electrically conductive member of the heating arrangement in accordance to the teachings of the invention. 
           [0020]      FIG. 11  is a plan view of another non-limiting embodiment of a sensor to measure the temperature of the electrically conductive member of a heating arrangement in accordance to the teachings of the invention. 
           [0021]      FIG. 12  is a plan view of a non-limiting embodiment of a moisture sensor or detector positioned over the electrically conductive member of a heating arrangement in accordance to the teachings of the invention. 
           [0022]      FIG. 13  is a non-limiting embodiment of an electrical system for monitoring the output of the moisture sensors shown in  FIG. 12  in accordance to the teachings of the invention. 
           [0023]      FIG. 14  is a view taken along lines  14 - 14  of  FIG. 12 . 
           [0024]      FIG. 15  is a side elevated view of another non-limiting embodiment of a moisture sensor positioned on the electrically conductive member of a heating arrangement in accordance to the teachings of the invention. 
           [0025]      FIG. 16  is a view similar to the view of  FIG. 14  showing another non-limiting embodiment of a moisture sensor or detector on a sheet of the windshield shown in  FIG. 2  in accordance to the teachings of the invention. 
           [0026]      FIG. 17  is a plan view of another non-limited embodiment of a moisture sensor or detector that can be used in the practice of the invention. 
           [0027]      FIG. 18  includes  FIGS. 18A and 18B .  FIG. 18A  is a non-limiting embodiment of a schematic of a system of the invention for monitoring the output signals of sensors or detectors in accordance to the teachings of the invention to monitor the real time performance of features, properties, or characteristics of accessories that provide the aircraft transparency with visual acuity, and  FIG. 18B  is a schematic of a system for scheduling repairs to, or replacements of, aircraft transparencies that the signals of the sensors or detectors indicate are performing outside of acceptable limits. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    As used herein, spatial or directional terms such as “inner”, “outer”, “left”, “right”, “up”, “down”, “horizontal”, “vertical”, and the like, relate to the invention as it is shown in the drawing on the figures. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, all numbers expressing dimensions, physical characteristics, and so forth, used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims can vary depending upon the property desired and/or sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between and inclusive of the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, e.g., 1 to 6.7, or 3.2 to 8.1, or 5.5 to 10. Also, as used herein, the term “positioned over” or “mounted over” means positioned on or mounted over but not necessarily in surface contact with. For example, one article or component of an article “mounted over’ or positioned over” another article or component of an article does not preclude the presence of materials between the articles, or between components of the article, respectively. 
         [0029]    Before discussing several non-limiting embodiments of the invention, it is understood that the invention is not limited in its application to the details of the particular non-limiting embodiments shown and discussed herein since the invention is capable of other embodiments. Further, the terminology used herein to discuss the invention is for the purpose of description and is not of limitation. Still further, unless indicated otherwise, in the following discussion like numbers refer to like elements. 
         [0030]    Non-limiting embodiments of the invention will be directed to an aircraft laminated transparency, and in particular to an aircraft windshield; the invention, however, is not limited to any particular type of aircraft transparency, and the invention contemplates the practice of the invention on aircraft windows of the type having a medium responsive to electric stimuli to increase or decrease visible transmission, e.g. but not limited to the type of window disclosed in U.S. Published Patent application 2007/0002422A1 and on aircraft windows of the type having an insulated air space between a pair of laminated sheets. The entire disclosure of the publications is hereby incorporated by reference. Further, the invention can be practiced on commercial and residential windows, e.g. but not limited to type disclosed in U.S. Pat. No. 5,675,944, which patent in its entireity is hereby incorporated by reference; a window for any type of land vehicle; a canopy, cabin window and windshield for any type of air and space vehicle, a window for any above or below water vessel, and a window for a viewing side or door for any type of containers, for example but not limited to a refrigerator, cabinet and/or oven door. Still further, the invention is not limited to the material of the layers or sheets of the transparency, and the layers or sheets can be made of, but not limited to, cured and uncured plastic sheets; annealed, heat strengthened, and heat and chemically strengthened, clear, colored, coated and uncoated glass sheets. Still further the invention can be practiced on windows having opaque sheets, e.g. but not limited to wood and metal sheets, and glass sheets having an opaque coating, and combinations thereof. 
         [0031]    Shown in  FIG. 1  is a non-limiting embodiment of an aircraft windshield  20  that can be used in the practice of the invention. The windshield includes a first glass sheet  22  secured to a second glass sheet  24  by a first interlayer  26 ; the second sheet  24  secured to a second vinyl-interlayer or sheet  28  by a first urethane interlayer  30 , and the second vinyl-interlayer  28  secured to a heatable member  32  by a second urethane interlayer  34 . An edge member or moisture barrier  36  of the type used in the art, e.g. but not limited to a silicone rubber or other flexible durable moisture resistant material is secured to (1) peripheral edge  38  of the windshield  20 , i.e. the peripheral edge  38  of the first and second sheets  22 ,  24 ; of the first and second vinyl-interlayers  26 ,  28 ; of the first and second urethane interlayers  30 ,  34  and of the heatable member  32 ; (2) margins or marginal edges  40  of outer surface  42  of the windshield, i.e. the margins  40  of the outer surface  42  of the first glass sheet  22  of the windshield  20 , and (3) margins or marginal edges  44  of outer surface  46  of the windshield  20 , i.e. margins of the outer surface  46  of the heatable member  32 . 
         [0032]    As is appreciated by those skilled in the art and not limiting to the invention, the first and second glass sheets  22 ,  24 ; the first and second vinyl-interlayers  26 ,  28  and the first urethane interlayer  30  form the structural part, or inner segment, of the windshield  20  and the outer surface  42  of the windshield  20  faces the interior of the vehicle, e.g. an aircraft  47  (shown only in  FIG. 18B ), and the second urethane layer  34  and the heatable member  32  form the non-structural part, or outer segment, of the windshield  20 , and the surface  46  of the windshield  20  faces the exterior of the aircraft. The heatable member  32  provides heat to remove fog from, and/or to melt ice on, the outer surface  46  of the windshield  20  in a manner discussed below. 
         [0033]    As can be appreciated the invention is not limited to the construction of the windshield  20  and any of the constructions of aircraft transparencies used in the art can be used in the practice of the invention. For example and not limited to the invention, the windshield  20  can include a construction wherein the vinyl interlayer  28  and the urethane interlayer  30  are omitted, and/or the sheets  22  and  24  are plastic sheets. 
         [0034]    Generally the glass sheets  22 ,  24  of the windshield  20  are clear chemically strengthened glass sheets; however, the invention is not limited thereto, and the glass sheets can be heat strengthened or heat tempered glass sheets. Further as is appreciated, the invention is not limited to the number of glass sheets, vinyl interlayers or urethane interlayers that make up the windshield  20  and the windshield  20  can have any number of sheets and/or interlayers. 
         [0035]    The invention is not limited to the design and/or construction of the heatable member  32 , and any electrically conductive heatable member used in the art to heat a surface of a sheet to melt ice on, and/or remove fog from the surface of the sheet can be used in the practice of the invention. With reference to  FIG. 2 , in one non-limiting embodiment of the invention, the heatable member  32  includes a glass sheet  60  having a conductive coating  62  applied to surface  64  of the glass sheet  60 , and a pair of spaced bus bars  66 ,  68  in electrical contact with the conductive coating  62 . The invention is not limited to the composition of the conductive coating  62 , for example and not limiting to the invention the conductive coating  62  can be made from any suitable electrically conductive material. Non-limiting embodiments of conductive coatings that can be used in the practice of the invention include, but are not limited to a pyrolytic deposited fluorine doped tin oxide film of the type sold by PPG Industries, Inc. under the trademark NESA®; a magnetron sputter deposited tin doped indium oxide film of the type sold by PPG Industries, Inc under the trademark NESATRON®; a coating made up of one or more magnetron sputter deposited films, the films including, but not limited to a metal film, e.g. silver between metal oxide films, e.g. zinc oxide and/or zinc stannate, each of which may be applied sequentially by magnetron sputtering, e.g. as disclosed in U.S. Pat. Nos. 4,610,771; 4,806,220 and 5,821,001 the disclosures of which in their entirety are hereby incorporated by reference. 
         [0036]    As can be appreciated, the invention is not limited to the use of an electrically conductive coating to heat the glass sheet  60  and contemplates the use of any type of member that can be electrically heated, e.g. but not limited to electrical conducting wires. The wires, e.g. the wires  69  shown in phantom in  FIG. 1  can be embedded in the interlayer  34  and electrical connected to the bus bars  66  and  68 . Such a heating arrangement is known in the art under the PPG industries Ohio Inc. registered trademark AIRCON and is disclosed in U.S. Pat. No. 4,078,107, which patent in its entirety is incorporated herein by reference. 
         [0037]    The invention is not limited to the design and/or construction of the bus bars and any of the types of bus bars used in the art may be used in the practice of the invention. Examples of bus bars that can be used in the practice of the invention, include, but not limited to, the types disclosed in U.S. Pat. Nos. (fired on silver ceramic glass frit); 4,623,389; 4,894,513; 4,994,650, and 4,902875, which patents in their entirety are hereby incorporated by reference. In the preferred practice of the invention, the bus bars are fired on silver ceramic glass frit, e.g. of the type disclosed in U.S. Pat. No. ______. Each of the bus bars  66  and  68  are connected by a wire  70  and  71 , respectively to a power source  72 , e.g. a battery to flow current through the bus bars  66  and  68 , and the conductive coating  62  to heat the conductive coating  62  and sheet  60  to remove ice and/or fog from the surface  46  of the windshield  20 . An on-off switch, a rheostat or variable transformer  73  is connected to one of the wires, e.g. between the wire  71  between the positions  71 A and  71 B to position the rheostat between the power source  72  and the bus bar  68  to vary or regulate the current flow through the bus bars  68  and  66 , and the conductive coating  62  to control the temperature of the conductive coating  62 . Although not limiting to the invention, ends  75  of the bus bar  66 , and ends  76  of the bus bar  68  are spaced from adjacent sides  78 - 81  of the glass sheet  60  to prevent arcing of the bus bars  66  and  68  with the metal body cover of the aircraft  47  (shown only in  FIG. 18B ). 
         [0038]    The discussion is now directed to the placement of sensors or detectors on selected components of the windshield  20 , to monitor the performance of the selected components of the windshield  20 , in accordance to the teachings of the invention. 
       Impact Sensor 
       [0039]    In one non-limiting embodiment of the invention, the windshield  20  is provided with an impact sensor or detector that generates a signal when an object hits or impacts the windshield, e.g. but not limiting to the invention, hits the outer surface  46  of the windshield  20 . For example and not limiting to the invention, as the aircraft travels down a runway during take-off or landing, foreign objects, e.g. stones are propelled through the air and can hit the outer surface  46  of the windshield. The impact detector mounted a sheet of the windshield can be used to indicate that one or more foreign objects have hit the windshield, and optionally the location on the outer surface  46  where the hit or impact occurred and the relative energy of the impact on the surface  46  of the windshield  20 . 
         [0040]    With reference to  FIG. 3 , in one non-limiting embodiment of the invention, one or more impact sensors or detectors (four detectors  83 A,  83 B  83 C and  83 D are shown in  FIG. 3 ) are mounted adjacent each one of the sides  78 - 81  of the glass sheet  60 . In this non-limiting embodiment of the invention, each of the impact detectors include a piezoelectric material, e.g. but not limited to a piezoelectric crystal. When the piezoelectric material is exposed to vibration, e.g. vibration of the glass sheet  60  (see  FIGS. 1 and 2 ) caused by a stone hitting the outer surface  46  of the glass sheet  60 , the piezoelectric material undergoes a compression or distortion and, as a result, produces an electric field, which can be used to activate or to cause an alarm and/or a recorder to be activated to announce and/or record the hit or impact. Further, using three or more impact detectors the location of the impact on the surface  46  of the windshield can be identified, as discussed below. 
         [0041]    With reference to  FIGS. 3 and 4  as needed, there is shown the heatable member  32  having one of the impact detectors  83 A-D mounted adjacent one of the sides  78 - 81 , respectively of the glass sheet  60 . The detectors  83 A-D are mounted on the conductive coating  62  and have one electrical contact of the detectors  83 A-D electrical connected to the conductive coating  62  and the other electrical contact of each of the detectors  83 A-D connected by a wire  84 A-D, respectively, to a rheostat or variable transformer  85 A-D, respectively. Each of the rheostats  85 A-D are electrically connected to the console  88  and the positive pole of the power supply  72  by way of wires  86 A-D, respectively (see  FIG. 4 ). In this manner, the power to the detectors  83 A-D is provided by the power supply  72 , controlled by the rheostats  85 A-D, respectively and changes in the electric field of each of the impact detectors  83 A-D measured or monitored by the comparator in the console  88 . As can be appreciated the invention is not limited to the manner in which power is provided to the detectors  83 A-D and any circuit arrangement can be used in the practice of the invention, e.g. and not limiting to the invention one electrical contact of the detectors  83 A-D can be mounted on any one or more of the sheets of the windshield and directly connected to one pole of a power supply dedicated to providing electrical power to the detectors and the other contact of the detectors  83 A-D connected to the other pole of the dedicated power supply. As can be appreciated, the invention is not limited to the type of power supply used in the practice of the invention and the power supply can generate alternating or direct current. 
         [0042]    With the arrangement shown in  FIGS. 3 and 4 , the piezoelectric material of the detectors  83 A-D undergoes a compression or distortion when the windshield is vibrated, e.g. an object hits the outer surface  46  of the windshield  20 . The vibration of the piezoelectric crystal of the detectors produces an electric field or current which is sent along one or more of wires  84 A-D of the detectors  83 A-D, respectively to the console  88  (see also  FIG. 18A ). The console  88  is provided with data processing equipment, e.g. software which analysis the signal forwarded along wires  86 A-D to determine the location of the impact by triangulation of the signals from selected ones or all of the detectors  83 A-D, and the magnitude of the impact, e.g. by the magnitude of the electric field, and stores the information. Electronic circuitry for electric file of impact detectors, e.g. piezoelectric crystal is well known in the art, e.g. see U.S. Pat. No. 6,535,126, which patent in its entirety is hereby incorporated by reference, and no further discussion is deemed necessary. In another non-limiting embodiment of the invention, signals from the detectors  83 A-D that exceed a predetermined amount of current are displayed on the console  88  to indicate that a visual inspection of the outer surface  46  of the windshield  20  should be made, and/or the windshield repaired, e.g. at the next scheduled stop of the aircraft, and optionally can be forwarded to a control center in a manner discussed below to schedule any needed repairs. 
         [0043]    As is appreciated, aircrafts during take-off, in-flight and landing vibrate which causes the impact detectors to vibrate and generate the electric field. The rheostats  85 A- 85 D or electronic filters can be used to pass only electric fields above a predetermined level. In this manner, the impact detector can be used to detect impacts to the windshield and to provide a performance log on the vibration of the aircraft. 
       Rupture Sensor 
       [0044]    In the following discussion, the rupture or crack detector, or sensor disclosed in U.S. Pat. No. 6,794,882, the entire disclosure of which is hereby incorporated by reference, will be used in the practice of the invention, however, as is appreciated, the invention is not limited thereto and any of the crack sensors or detectors known in the art can be used in the practice of the invention. A non-limiting embodiment of a rupture sensor or detector of the type disclosed in U.S. Pat. No. 6,794,882 is shown in  FIG. 5  and designated by the number  89 . The crack sensor  89  includes an electrically conductive strip  90  extending along or around substantially the entire outer periphery  38  (see  FIG. 1 ) of a major surface of one of the sheets  22 ,  24 ,  28  and  60  of the windshield  20 . In  FIGS. 5 and 6 , the conductive strip  90  is shown mounted over the electrically conductive layer  62  of the glass sheet  60 , surrounds the bus bars  66  and  68 , and electrically isolated from the conductive coating  62  by an electrically insulating layer  96 , e.g. a urethane layer or an electrically non-conductive coating layer. 
         [0045]    The conductive strip  90  is mounted on the conductive coating  62  spaced from the sides  78 - 81  of the sheet  60  as shown in  FIG. 5 . As can be appreciated, the conductive strip  90  can decrease visibility through that portion of the glass sheet over which it is deposited, and therefore, the maximum width of the conductive strip  90  depends upon the required or specified operator viewing area through the windshield  20 . Aircraft transparencies, e.g. windshields have specific safety requirements specifying the viewable (or transparent) area required. However, if the conductive strip  90  is formed from a substantially or fully transparent material that still has the required conductive properties, the placement of the conductive strip  90  with respect to the sheets of the windshield would be highly variable. For example, and not limiting to the invention, the conductive strip  90  can form an inner or small strip or band more centrally located on the surfaces of the sheets. Alternatively, the conductive member  90  can include multiple and concentric strips or bands emanating from a center of the glass sheets outwardly towards the periphery  38  of the sheets  22 ,  24 ,  28  and  60 . Alternatively still, the conductive strip  90  can be in the form of an “X” or other shape, depending upon the anticipated nature and course of a rupture or break in the sheets. 
         [0046]    As discussed above, the conductive coating  62  is electrically isolated from the conductive strip  90  by an electrically insulating layer  96 . As can be appreciated, the insulating layer  96  can mask the presence of a small crack in the glass sheet  32  by preventing the conductive strip  90  from separating. This limitation is eliminated by applying the conductive strip  90  on an uncoated surface portion of the glass sheet  60 , e.g. and not limiting to the invention, by surrounding the coating  62  and the bus bars  66  and  68  with a strip of uncoated glass  92  (shown only in  FIG. 2 ). The uncoated glass strip  92  can be provided in any convenient manner, e.g. by masking the glass surface during the coating process, or abrasively or chemically removing the coating from the glass surface. Because the glass is chemically strengthened it is preferred to mask the areas during the coating process to avoid surface damage that can cause the tempered glass to fracture. 
         [0047]    As can be appreciated, the conductive strip  90  can be applied to any surface of any one of the sheets of the laminated windshield  20 , however, in the preferred practice of the invention the conductive strip  90  is preferably between the sheet the uncoated portion  92  of the sheet  60  and the urethane layer  34 . In the non-limiting embodiment shown in  FIG. 5 , the conductive strip  90  is mounted over the uncoated potion  92  of the sheet  60  (see  FIG. 2 ) and extends around substantially the entire outer periphery of the coating layer  62 . The conductive strip  90  has a first termination surface  104  and a second termination surface  106 . The distance or gap between the first termination surface  104  and the second termination surface  106  should be sufficient to prevent any descriptive electrical field communication between the termination surfaces  104  and  106 . 
         [0048]    The rupture sensor  90  further includes an electrical power source  108  in electronic communication with the conductive strip  90  to apply an electrical potential to the conductive strip  90 . The power source  108  can be any conventional electrical source, such as, but not limited to, a battery, an electrical generator, and the like. Further, the rupture sensor  90  includes an electrical measurement mechanism  110 , such as an ohmmeter, in communication with the conductive strip  90  for measuring the electrical potential of the conductive strip  90 . A control mechanism  112 , such as a software and a computer, is used to control and communicate with both the electrical power source  108  and the electrical measurement mechanism  110 . This control mechanism  112  can be used to command the electrical power source  108  to provide a predetermined or specifically set electrical potential to the conductive strip  89  and, after application, the control mechanism  112  can collect and/or calculate the electrical potential of the conductive strip  90  via the electrical measurement mechanism  110 . All of the electrical power source  108 , the electrical measurement mechanism  110  and the control mechanism  112  can be combined in a single unit or instrument, e.g. the console  88  (see  FIG. 18 ) or can be individual units (see  FIG. 5 ). 
         [0049]    The electrical power source  108  applies a set voltage to the conductive strip  90 , as set or specified by the control mechanism  112 . This set voltage allows current to flow through the conductive strip  90 . The electrical measurement mechanism  110  is connected to the conductive strip  90  through a first lead  114  and a second lead  116 . The first lead  114  is connected to the first termination surface  104  and the second lead  116  is connected to the second termination surface  106 . This connection allows the conductive strip  90  to act as an electrical circuit when the electrical power source  108  applies an electrical potential. 
         [0050]    The electrical measurement mechanism  110  reads or measures the current flowing through the conductive strip  90  via the first lead  114  connected to the first termination surface  104 , and the second lead  116  connected to the second termination surface  106 . Since the electrical power source  108  is applying a set voltage, and the electrical measurement mechanism  110  is reading or measuring the current flowing through the conductive strip  90 , the electrical measurement mechanism  110  (or the control mechanism  112 ) is able to calculate the resistance value of the conductive strip  89 . 
         [0051]    When a rupture or crack occurs and propagates in the glass sheet  60 , it will eventually reach the conductive strip  90 . As the crack begins to move through and break a section of the conductive strip  90 , the resistance value calculated by either the electrical measurement mechanism  110  or the control mechanism  112  begins to increase. This resistance value increase indicates a rupture or crack in the glass sheet  60 . When the crack fully traverses and breaks the conductive strip  90 , the resistance value reaches infinity and indicates a serious rupture condition. 
         [0052]    The conductive strip  90  can be a conductive coating material formed from any suitable electrically conductive material, such as a metal, metal oxide, a semi-metal, an alloy, or other composite material. The conductive strip  90  can also be opaque or transparent. Further, the conductive strip  90  can be a conductive coating material formed from a ceramic paint or electrically conductive ink. The conductive material must be a material that will crack or separate when the glass sheet cracks or must otherwise change its electrical properties in a manner that allows for detection of a change. The conductive strip  90  can be deposited on a surface of one or more of the glass sheets  22 ,  24 ,  28  and  60  through conventional thin film deposit methods or conventional thick film deposit methods; conventional adhesion manufacturing methods; screening, or other similar process. In one embodiment, the conductive member  90  is a conductive indium tin oxide coating. 
         [0053]    The invention contemplates applying a conductive strip on more than one sheet, e.g. but not limiting to the invention, applying a conductive strip  90  on a surface of the glass sheets  22 ,  24 ,  28  and  60 . As is appreciated, when a conductive strip is is placed on more than one sheets, each one of the conductive strips  90  has it own electrical power source  108 , or one power source is provided and is electrically connected to two or more of the conductive strips  90  and a rheostat is provided for each conductive strip  90  for controlling voltage to each of the conductive strips  90  in a manner discussed above for the impact sensors  83 A-D, and discussed below for the rupture sensor. Similarly, one or multiple electrical measurement mechanisms  110  can be used to read and measure the electrical potential or current flowing through each of the conductive strips  90  on the sheets  22 ,  24 ,  28  and  60  of the windshield  20 . In this manner the condition of each of the glass sheets  22 ,  24 ,  28  and  60  can be monitored. 
         [0054]    The control mechanism  112  and/or the central or multiple dedicated electrical measurement mechanisms  110  are equipped to identify each individual conductive strip  90  on a glass sheet  22 ,  24 ,  28  and  60  and calculate the electrical potential (resistance value) for each conductive strip  90 . In this manner, the vehicle operator receives an indication from the alarm mechanism  118  of the existence and extent of a rupture in each of the glass sheets  22 ,  24 ,  28  and  60  due to the breaking or bridging of the associated conductive strip  90 . As can be appreciated, during a rupture condition, it typically proves difficult to decipher which glass sheet has been ruptured or cracked, and providing a conductive strip  90  on each of the sheets  22 ,  24 ,  28  and  60  allows the vehicle operator to identify the sheet that has the failure condition. 
         [0055]    The conductive strip  90  can be embedded in the interlayers  26 ,  30  and  34  between the sheets  22 ,  24 ,  28  and  60  as long as the conductive strip  90  is in contact with its respective one of the sheets  22 ,  24 ,  28  or  60  in a manner that will break or disrupt the conductive strip  90  in the event the surface of the glass sheet having the conductive strip cracks. In order to enhance identifying the rupture location on the surface, multiple conductive strips  90  can be placed in a grid or array pattern over the major surface of the sheets, or optionally an array pattern can be used adjacent the periphery  38  of the sheets as shown in  FIG. 7  so as not to minimize reducing the vision area of windshield  20 . 
         [0056]    In the non-limited embodiment of the invention shown in  FIG. 7 , each one of sides  120 - 123  of glass sheet  125  has two rows  132  and  134  of conductive stripes at or adjacent margin  135  of glass sheet  125  to provide an array of conductive stripes to more definitively identify where a rupture or crack in the sheet  126  has occurred. More particularly, the first row  132  of conductive stripes includes conductive stripes  136 - 139  at the corners  141 - 144 , respectively of the sheet  125 , and conductive strips  146  and  147  at the sides  121  and  123 , respectively of the sheet  125 . With continued reference to  FIG. 7 , end  136 A of the strip  136  is adjacent to and spaced from end  139 B of the strip  139  at the side  120  of the sheet  125 ; end  136 B of the strip  136  is spaced from and adjacent to end  146 A of the strip  146 , and end  146 B of the strip  146  is adjacent to and spaced from end  137 A of the strip  137 , at the side  121  of the sheet  125 ; end  137 B of the strip  137  is adjacent to and spaced from the end  138 A of the strip  138  at the side  122 ; end  138 B of the conductive strip  138  is adjacent to and spaced from end  147 A of the strip  147 , and end  147 B of the strip  147  is adjacent to and spaced from end  1   39 A of the strip  139 , at the side  123 , of the sheet  125 . 
         [0057]    The second row  134  of the conductive strips includes conductive strips  150 - 153 . The conductive strip  150  extends between sides  121  and  123  of the glass sheet  125 ; has its end  150 A adjacent to and spaced from end  151 B of the strip  151 , and its end  150 B adjacent to and spaced from end  153 A of the strip  153 . The conductive strip  151  extends between sides  122  and  120  of the glass sheet  125  and has its end  151 A adjacent to and spaced from end  152 B of the strip  152 . The conductive strip  152  extends between sides  121  and  123  of the glass sheet  125  and has its end  152 A adjacent to and spaced from end  153 B of the strip  153 . The conductive strip  153  extends between sides  120  and  122  of the glass sheet  125  and has its end  153 B adjacent to and spaced from end  152 A of the strip  152 . 
         [0058]    The ends A and B of each of the strips  136 - 139 ,  146 ,  147  and  150 - 153  are individually electrically connected to the electrical power source  108  (see  FIG. 5 ) to apply an electrical potential to the conductive strips  136 - 139 ,  146 ,  147  and  150 - 153 , and to the electrical measurement mechanism  110  for measuring the electrical potential of the conductive strips  136 - 139 ,  146 ,  147  and  150 - 153 . The control mechanism  112  controls and communicates with both the electrical power source  108  and the electrical measurement mechanism  110  as discussed above to command the electrical power source  108  to provide a predetermined or specifically set electrical potential to the conductive strips  136 - 139 ,  146 ,  147  and  150 - 153  and, after application, the control mechanism  112  can collect and/or calculate the electrical potential of the conductive strip  136 - 139 ,  146 ,  147  and  150 - 153  via the electrical measurement mechanism  110 . All of the electrical power sources  108 , the electrical measurement mechanisms  110  and the control mechanisms  112  for the conductive stripes  136 - 139 ,  146 ,  147  and  150 - 153  can be combined in a single unit or instrument, e.g. the console  88  (see  FIG. 13 ) or can be individual units. 
         [0059]    With continued reference to  FIG. 7 , the arrangement of two rows  132  and  134  each having spaced conductive strips, e.g. stripes  136 - 139 ,  146  and  147  in row  132 , and the conductive stripes  150 - 153  in the row  134  provides for a closer approximation of the position of the crack or break in the glass sheet. More particularly and not limiting to the invention, crack  156  fractures the conductive strips  146  and  151 , positioning the crack  156  in the center area of the side  121  of the sheet  125 ; crack  158  fractures the conductive strips  139  and  153 , positioning the crack  158  in the side  123  adjacent the side  138  of the sheet  125 . As can be appreciated the arrangement of the conductive strips as shown in  FIG. 5  is useful, but not limited to, a study to determine if cracks are a random event or caused by stress imposed on the edges of the windshield by the design of the frame securing the windshield  20  in the body of the aircraft. 
       Arcing Sensor or Detector 
       [0060]    The discussion is now directed to non-limiting embodiments of the invention for monitoring the performance of the heating arrangement which includes the bus bars  66 ,  68  and the electrically conductive member, e.g. the electrically conductive coating  62 , or wires embedded in the interlayer  34  to determine the occurrence of, or a high probability of the occurrence of, arcing indicating that the windshield should be repaired, or replaced before the windshield is damaged by arcing, or before arcing occurs, respectively. Arcing of interest in the present discussion, but not limited thereto is electric arcing over a crack in the coating  62  and/or bus bars  66  and  68 , and/or separation of the bus bars  66 ,  68  and/or coating  62 . As is appreciated by those skilled in the art, impacts to the glass sheet  60  of the heatable member  32  can result in fractures in the glass sheet  60  that result in fractures in the coating  62 . Further, moisture moving through the moisture barrier  36  of the windshield  20  (see  FIG. 1 ) can cause delamination of the laminated windshield. The delamination of the windshield can result in separation of one or both of the bas bars  66  and  68  from the conductive coating, or the wires embedded in the interlayer  38 . The electric arcing over cracks in the conductive coating  62  and separations between the bus bars and the coating result in spot heating which can increase sufficiently to cause the glass  60  of the heatable member  32  to fracture. 
         [0061]    With reference to  FIGS. 8 and 9  there is shown a non-limiting embodiment of another heating member of the invention identified by the number  160 . The heating member  160  includes the bus bars  66  and  68  electrically connected to the conductive coating  62  on the glass sheet  60  (sheet  60  shown in  FIGS. 1 and 2 ). As previously discussed, the voltage to the conductive member  62  is provided by current moving from the power source  72  through the wire  71  and the switch or rheostat  73 , to the end  76  of the bus bar  68 , through the bus bar  68  and the coating  62  to the bus bar  66 , through the wire  70  at the end  75  of the bus bar  66  to the power source  72  (see also  FIG. 2 ). With reference to  FIGS. 8 and 9  as needed, arcing sensor or detector  164  includes a comparative circuit  165  having input side connected to opposite end  166  of the bus bar  68  by a wire  167 , and connected to the current input wire  71 , which is connected to the end  76  of the bus bar  68  (see also  FIG. 2 ). In operation, a reference voltage is provided to the comparator circuit  165  by the wire  71  connected to the end  76  of the bus bar  68 . 
         [0062]    The electrical power flows through the wire  71  to the bus bar  68 , through the conductive coating  62  to the opposite bus bar  66 . A portion of the power passing through the bus bar  68  is directed by the wire  167  at the end  166  of the bus bar  68  to the comparative circuit  165 . The comparator circuit  165  continuously or periodically compares the reference voltage from the wire  71  to the measured voltage of the wire  167 . When the measured voltage of the wire  167  differs from the reference voltage by a predetermined amount, an output signal from wire lead  168  of the comparator  165  is generated which can terminate the power being supplied to the bus bars and/or send a status report of the performance of the heatable member  160  in a manner discussed below. More particularly, if the measured voltage from the wire  167  decreases it can be an indication that current is not moving through the bus bar  68 . If the measured voltage from the wire  167  increases, it can be an indication that the current moving through the bus bar  68  has increased, possibly as a result of an increase in the resistance of the conductive coating  62 , or the bus bar  66 , e.g. caused by a crack in the conductive coating  62 , or one or both of the bus bars  66 ,  68 . As is appreciated the sensor  164  does not have the capability of identifying what is causing an increase or decrease in the voltage measured at the end  166  of the bus bar  68 , however, an increase above a high norm value, or a decrease below a low norm value is an indication that the performance of the heatable member  160  is changing and that remedial action, e.g. discontinue the electrical power input to the heating arrangement, making a repair to the heatable member  160 , or a replacing the windshield  20 , should be taken. As can be appreciated, the comparative circuit  164  can be mounted in the console  88  (see  FIG. 18A ). 
         [0063]    The sensor  164  is of the type disclosed in U.S. Pat. No. 4,902,875 the entire disclosure of which is hereby incorporated by reference. As is appreciated, the invention is not limited to the type of sensor disclosed in U.S. Pat. No. 4,902,875, and any sensor that measures the voltage or current of the conductive member  32  (see  FIG. 2 ) or  160  (see  FIG. 8 ) to indicate changes in the voltage or current passing through bus bars  66 ,  68  and/or conductive coating  62  of the conductive member  32  or  160  can be used in the practice of the invention. 
         [0064]    With reference to  FIGS. 8 and 10 , as needed there is shown another non-limiting embodiment of a sensor designated by the number  170  that can be used can be used in the practice of the invention to measure the temperature of the conductive coating  62  and prevent over heating of the heatable member of the windshield  20 . The sensor  170  is of the type disclosed in U.S. Pat. No. 4,994,650, the entire disclosure of which is hereby incorporated by reference. As is appreciated, the invention is not limited to the type of sensor disclosed in U.S. Pat. No. 4,994,650 and any sensor that measures the temperature of a conductive surface to prevent over heating of the conductive surface can be used in the practice of the invention. 
         [0065]    The sensor  170  is an electric field detector that is electrically connected with the coating  62  to monitor the coating voltage at a predetermined location between bus bars  66  and  68 . The sensor  170  is connected to a voltage comparative system  171  by way of wire  172 . Although not limiting in the present invention, in the particular embodiment of the invention illustrated in  FIG. 8 , the position of the sensor  170  is spaced in close proximity to the bus bar  68  and is in the upper corner of the conductive member  160  so that it&#39;s presence is minimized when viewing through the windshield  20 . As is appreciated, the position of the sensor  170  can be selected to be at other locations between bus bars  66 ,  68 , and can also extend into the viewing area of the windshield  20 , if permissible. 
         [0066]    With continued reference to  FIGS. 8 and 10 , the voltage comparator  171  is connected to the power source  72  by wire  174 . In principle, when power is applied to the bus bars  66 ,  68 , an electric field is established in the conductive coating  62  between the bus bars  66 ,  68 . The voltage within the electric field is fairly linearly distributed such that a voltage at a particular location in the coating  62  is proportional to the physical location of that particular location relative to the bus bars. For a given location, if the applied voltage changes, the voltage at that given location will change proportionally. As a result, when a predetermined amount of change in the coating voltage is determined, it can be assumed that a current to the bus bars is discontinued or there is a reduction of current through the bus bars due to increased resistance of the bus bars. The increased resistance can be due to a discontinuity, i.e. break in the bus bar or a crack in the conductive coating. In this manner, the electric field detector  170  operates to detect a break in the bus bars and/or conductive coating by monitoring the voltage in the coating  62  at the position of the sensor  170 . Although not limiting in the present invention, for the purpose of the following discussion, the current flows through the coating  62  from the bus bar  68  to the bus bar  66  so that the voltage drop within the coating  62  is from the bus bar  68  to the bus bar  66 . 
         [0067]    In the particular non-limiting embodiment illustrated in  FIGS. 8 and 10 , a reference voltage is provided to the comparator  171  from the power source  72  through the wire  174 . The current flows through the bus bar  68 , and through the coating  62  to the bus bar  66 . A circuit of the comparator  171  monitors the voltage of the coating  62 . The comparator  171  continuously compares the reference voltage from the power source  72  to the measured voltage of the coating  62  via the detector wire  172 . When the measured voltage from the detector wire  172  differs from the reference voltage by a predetermined amount, an output signal from the comparator  171  is sent through lead  176  to the console  88 . The difference in the voltage is indicative of that amount of a shift in the performance of the bus bars  66 ,  68  and/or coating  62 , e.g. due to a break in the bus bars, a separation of the bus bars and coating, and/or a crack in the coating  62 . The console  88  analysis the information received from the comparator  171  and takes appropriate action which includes but is not limited to, terminate the power input to the bus bar  68 , or indicate that the performance of the coating  62  and/or bus bars  66  and/or  68  of the conductive member  160  has changed and that maintenance or repair is or will be needed to prevent arcing and associated localized overheating of the conductive member  62 . 
         [0068]    As can be appreciated, the comparator  165  ( FIG. 9 ) and/or  171  ( FIG. 10 ) can be included in the circuitry of the console  88 , or can be individual or combined systems outside of the console  88 . 
       Conductive Coating Temperature Sensor 
       [0069]    With reference to  FIG. 11 , there is shown a sensor or detector identified by the number  200  that can be used to measure the temperature of the conductive coating  62  of the heatable member  32  to prevent over heating of the heatable member. The sensor  200  is of the type disclosed in U.S. Pat. No. 4,894,513 the entire disclosure of which is hereby incorporated by reference. As is appreciated, the invention is not limited to the type of sensor disclosed in U.S. Pat. No. 4,894,513, and any sensor that measures the temperature of an electrically conductive member can be used in the practice of the invention. 
         [0070]    With continued reference to  FIG. 11 , the temperature sensor  200  of this non-limiting embodiment of the invention includes one or more wire loops, e.g. and not limiting to the invention, the sensor  200  shown in  FIG. 11  has wire loops  202 - 206 . As is appreciated, the invention is practiced with the sensor  200  having any number of wired loops. If only one wire loop is used, it preferably extends within the conductive coating  62  to a position where, based on the conductive member design and/or experience, a hot spot is anticipated. Each of the wire loops  202 - 206  is a resistance type device, i.e., its resistance changes as its temperature changes. Although not limiting in the present invention, the wire loops  202 - 206  are preferably a blackened 34 to 36 gage iron nickel wire having a resistance that changes at a rate of 0.008 ohms/foot degree centigrade (0.026 ohms/meter degree centigrade). 
         [0071]    In the particular embodiment illustrated in  FIG. 11 , the wire loops extend across the conductive coating  62  between the bus bars  66  and  68 , and except for the looped ends  208  of the wire loops  202 - 206  are generally parallel to the bus bars. The wire loops  202 - 206  are preferably positioned along the surface of the interlayer  34  overlaying the conductive coating  62  (see  FIG. 1 ). The wire loops  202 - 206  are electrically isolated from the coating  62  so as to insulate the circuitry of the conductive member  32  from the voltage drop comparator circuit  212 - 216  of the temperature sensor  200  and prevent shorting of the circuit. As an alternative, the wires of the wire loops can be provided with an insulating cover or be embedded within the interlayer  34  in a similar manner as the heating wires of the AIRCON system are embedded in the interlayer  34 . 
         [0072]    With continued reference to  FIG. 11  the comparator circuits  212 - 216  monitor the temperature of its respective one of the wire loops  202 - 206  based on the resistance of the wire of the wire loops which changes as the temperature of the conductive coating  62  of the heatable member  32  changes. When the average temperature of any one of the wire loops  202 - 206  reaches a set value, the circuit  212 - 216  will interrupt the power from the power supply  72  to the bus bar  68 , or set an alarm or signal that the temperature of the conductive member  62  is rising and corrective action is recommended. For a detailed discussion of a circuit that can be used in the practice of the invention, but not limiting to the invention, attention is directed to U.S. Pat. No. 4,894,513. 
         [0073]    As can now be appreciated, the comparator circuits  212 - 216  can be positioned in the consol  88  (see  FIG. 18A ). 
         [0074]    The invention also contemplates a retrofit arrangement that can be used to prevent over heating of aircraft transparencies that have heatable members, e.g. but not limited to the invention, similar to the heatable member  32 . With reference to  FIG. 2 , in one non-limiting embodiment of the invention, a controller  230  (shown in phantom in  FIG. 2 ) is mounted external of the windshield  20  (see  FIG. 1 ). The controller  230  includes an ohm-meter to measures the resistance of the bus bars  66  and  68  and a comparator. When the resistance as measured by the ohm-meter exceeds a predetermined value a signal is sent by the comparator along wire  232  (shown in phantom) to open the switch  73  to stop the flow of current from the power supply  72  to the bus bars  66  and  68 . 
       Moisture Sensor 
       [0075]    As discussed above and as shown in  FIG. 1 , the windshield or transparency  20  has an outboard moisture seal  36  that is a barrier to prevent moisture from entering between the glass sheets  22 ,  24  and  60 , and the plastic interlayers or sheets  26 ,  28 ,  30  and  34  of the windshield  20 . More particularly, when the moisture seal  36  fails, e.g. cracks or de-bonds due to erosion caused by wind and rain, moisture enters between the sheets of the windshield. While the cracking or de-bonding of the moisture seal is not a structural issue, when moisture moves between the sheets, the windshield  20  can de-laminate, and/or the heating arrangement can be damaged and fail, reducing the service life of the windshield. When de-lamination of the windshield  20  occurs, the rate and amount of moisture entering between the sheets increases, accelerating the degradation of the windshield. As can be appreciated, it would be advantages to monitor the condition or performance of the moisture barrier  36 , and replace or repair the moisture barrier before degradation of the windshield caused by moisture penetration begins or accelerates. 
         [0076]    With reference to  FIGS. 12-14  as needed, there is shown one non-limiting embodiment of the invention having moisture sensors  250 - 253  positioned on the conductive coating  62  adjacent the sides  78 - 81 , respectively of the conductive coating  62  as shown in  FIG. 12 . Each of the sensors  250 - 253  include a layer  256  of a moisture sensitive electrically resistant material (hereinafter also referred to as “moisture sensitive layer”) deposited on the conductive coating  62 , and an electrically conductive layer  258  deposited over the moisture sensitive layer  256  (see  FIG. 14 ). Each of the conductive layers  258  of each of the sensors  250 - 253  are individually connected to a positive pole of a DC power source, e.g. the power source  72  by way of a wire  260 A-D, respectively. Optionally the wires are individually connected by way of wire  260 A-D, respectively to the positive pole of the DC power source  72  through a reostate or variable transformer in a similar manner as the impact sensors  83 A-D are connected to the power source  72  (see  FIG. 4 ) to regulate the power input to each of the conductive layers  256  of the sensors  250 - 253 . The invention is not limited to the material of the moisture sensitive layer  256  and any moisture sensitive electrically resistant material can be used in the practice of the invention, e.g. but not limited to titanium dioxide, and/or the materials disclosed in U.S. Pat. Nos. 4,621,249 and 4,793,175, the disclosures in their entirety are hereby incorporated by reference. Further the invention is not limited to the material of the electrically conductive layer  258  over the moisture sensitive layer  256  and any electrically conductive material, e.g. but not limited to aluminum, copper, gold and silver can be used. The sensors  250 - 253  in one non-limiting embodiment of the invention are elongated members as shown in  FIG. 12  including a conductive coating  62  of indium tin oxide, a moisture sensitive layer  256  of sputtered titanium dioxide film and an electrically conductive layer  258  of sputtered gold (see  FIG. 14 ). 
         [0077]    As the moisture sensitive layer  256  absorbs moisture, the resistance of the moisture sensitive layer  256  decreases. As can be appreciated, the resistance of the layers  256  can be measured and/or monitored in any usual manner. In one non-limiting embodiment of the invention, wires  262 A-D are connected to the conductive layers  258  of the sensors  250 - 253 , respectively. The voltage difference between each pair of wires  260 A and  262 A,  260 B and  262 B,  260 C and  262 C,  260 D and  262 D is measured and/or monitored by comparator  270  (see  FIG. 13 ). With reference to  FIG. 13 , the wire  260  of each of the sensors  250 - 253  is connected to comparator  270 . The comparator  270  monitors the resistance of the moisture sensitive layer  256  of each one of the sensors  250 - 253 . When the voltage difference exceeds a predetermined amount, a signal is forwarded along wire  272  to an alarm or monitor. As can now be appreciated, the comparator  270  can be positioned in or be a part of the consol  88  (see  FIG. 18A ). 
         [0078]    In the non-limiting embodiment of the invention shown in  FIGS. 12 and 14 , the positive pole (+) of a power source, e.g. but not limiting to the invention, the power source  70  (see  FIG. 2 ) has its positive pole (+) connected to the conductive layer  258  of each of the sensors  250 - 253  by wire  260 A-D, respectively and the negative pole (−) connected to the conductive coating  62  of the heatable member by the wire  70  connected to the bus bar  66 . Adjacent ends of the layer  258  of the sensors  250 - 253  shown in  FIG. 12  are spaced from each other a sufficient amount to prevent a current from arcing between adjacent ends of the sensors  250 - 253  and bus bars  66  and  68 . 
         [0079]    As can be appreciated, in the non-limiting embodiment of the invention shown in  FIGS. 12 and 14 , the sensors  250 - 253  are operational when current is moving through the conductive coating  62 . However, in the event it is desired to have the moisture sensors operational at all times, the non-limited embodiment of the invention shown in  FIG. 15  can be used. The embodiment of sensor  274  in  FIG. 15  is similar to the embodiment of the sensor  251  shown in  FIG. 14  except that the sensor  274  includes an electrically non-conductive layer, e.g. a plastic film  276  applied over the conductive coating  62 , and an electrically conductive layer  278  similar to the layer  258  over the plastic film  276  and in electrical contact with the moisture sensitive layer  256 . In the embodiment shown in  FIG. 15 , the wires  260 A and  280  are connected to the power supply, and the wire  278  is connected to the comparator  270  (see  FIG. 13 ). 
         [0080]    In the event it is desired to have a moisture sensor of the invention on one or more of the sheets, e.g. but not limited to the sheet  24  of the windshield  20 , and on the uncoated surface  92  of the sheet  60  (see  FIG. 2 ), the embodiment shown in  FIG. 16  can be used. The embodiment of sensor  280  shown in  FIG. 16  is similar to the sensor  274  shown in  FIG. 15  except that the plastic film  276  of the sensor  274  is eliminated. As shown in  FIG. 16 , the urethane interlayer  30  covers the glass sheet  24  and the moisture sensor  280 . 
         [0081]    Shown in  FIG. 17 , is another non-limiting embodiment of a moisture sensor of the invention designated by the number  282 . The sensor  282  includes a pair of comb electrodes  284  and  286  electrically connected to the moisture sensitive layer  258 . Wires  288  and  290  electrically connect the electrodes  284  and  286  respectively to an electrical power supply. As can now be appreciated, the invention is not limited to the design and/or construction of the moisture sensor and any of the designs and/or construction of moisture sensors known in the art, e.g. but not limited to those disclosed in U.S. Pat. Nos. 4,621,249; 4,793,175, and 5,028,906 can be used in the practice of the invention. The entire disclosures of the patents are hereby incorporated by reference. 
         [0082]    As can be appreciated, the invention is not limited to the number or arrangement of moisture sensors or detectors positioned on the sheets  22 ,  24 ,  26 ,  28 ,  30 ,  34  and  60  of the windshield  20 . For example and not limiting to the invention, the moisture sensor can be a single strip that extends around the margin of one or more of the sheets as shown for the conductive strip  89  of the crack sensor or detector (see  FIG. 5 ), or the moisture sensor can be an elongated strip along each side of the sheets as shown for the moisture sensors  250 - 253  shown in  FIG. 12 , or the moisture sensors can have the arrangement shown in  FIG. 7  for the conductive members  136 ,  137 ,  138 ,  139 ,  146 ,  147 , and  150  of the crack sensor. 
         [0083]    In another non-limiting embodiment of the invention, the moisture sensor can be used as a crack detector. More particularly, when the moisture sensor, e.g. the moisture sensor  274  shown in  FIG. 15  fractures and separates, current no longer moves through the electrically conductive layers  258  and  278  (see  FIG. 15 ) which can be an indication of a crack in the sheet  22 ,  24  an/or  60  associated with the moisture sensor. 
       Control System 
       [0084]    With reference to  FIG. 18 , there is shown one non-limiting embodiment of the invention to monitor the performance of the transparency  20  of the invention and to timely schedule maintenance of, e.g. repairs to, or replacement of, transparencies, e.g. aircraft windshields that are performing outside acceptable limits. The windshield  20  of the invention can have one or more of the impact, rupture, arcing, temperature and/or moisture sensors or detectors, e.g. but not limited to the types discussed above. With reference to  FIG. 18A , the wires from the sensors having signals carrying data regarding the performance of components of the windshield are connected to one part of a connector, e.g. an electrical output connector  300 . The output connector  300  is not limiting to the invention and can be any of the types used in the art to provide external electrical access to an electric device embedded within a laminate. The output connector  300  is connected to an input electrical connector  302 , e.g. other part of the connector, connected to the console  88  by a cable  304 . In one non-limiting embodiment of the invention, the console  88  includes a computer having software to read and analyze the signals from the sensors or detectors to monitor and/or determine the performance of the components of the windshield. Monitor  306  provides visual display, and speaker  308  provides audible information regarding the performance of the windshield, and/or individual components of the windshield. The console  88  can include an alarm  310  to bring attention to the monitor  306 . Placing the console  88  in the aircraft provides the personnel within the aircraft with real time performance of the windshield. 
         [0085]    In another non-limiting embodiment of the invention, the console  88  has a wireless transmitter and receiver  312 ; the transmitter  312  transmits signals  314  to a transmitting tower  316 . The signals  314  carry data on the performance of the windshield  20 . The tower  316  transmits a signal  318  carrying the data on the performance of the windshield  20  to a satellite  320 . The satellite  320  transmits a signal  322  carrying the data on the performance of the windshield to a control center  324 . The data received is studied and the appropriate action to be taken is scheduled. In one non-limiting embodiment of the invention, based on the information received, personnel at the control center determine what action, if any, is needed. If action such as repairs to the windshield or replacement of the windshield, is needed, a signal  326  providing a repair schedule is transmitted to the satellite  320 . The satellite  320  transmits a signal  328  having the repair schedule to the tower  316 . The tower  316  transmits a signal  330  having the repair schedule to the console  88  and to a maintenance center  332  geographically close to the designated repair location (usually the next scheduled stop for the aircraft) to arrange to have all parts, equipment and personal need at the designated repair location. 
         [0086]    In one non-limiting embodiment of the invention, if the data from the sensors indicate that the windshield  20  has to be replaced, the repair schedule can include shipment of the windshield to the next scheduled stop of the aircraft; if the windshield has to be replaced with some urgency, the repair schedule would include a change to the flight plan to land immediately and a windshield will be there, or will arrive shortly. The passengers can optionally be transferred to another plane, or wait until the repair is completed. If a repair is scheduled, and the repair can be made without removing the windshield, the repair schedule can provide for personnel and repair parts to be provided at the designated repair location. 
         [0087]    As can be appreciated, the invention is not limited to wireless transmission of signals carrying information and the transmission can be made by land lines. Further, the signals can be transmitted between locations solely by satellite, or solely by transmission towers, and by combinations thereof. 
         [0088]    The invention is not limited to the embodiments of the invention presented and discussed above which are presented for illustration purposes only, and the scope of the invention is only limited by the scope of the following claims and any additional claims that are added to applications having direct or indirect linage to this application.