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FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to switches and, more particularly, a fail-safe automotive switch.  
         BACKGROUND OF THE INVENTION  
         [0002]    The automotive industry is under constant pressure to make vehicles safer and more reliable. Additionally, there is also market pressure to provide more features on each car. Still further, there are regulatory pressures on automobile manufacturers to provide warnings and other instruments indicating to a driver that the failure of a component has occurred. Still further, consumers are demanding that the vehicles provide more and more features at a lesser and lesser cost.  
           [0003]    As can be expected in this competitive environment, auto manufacturers are demanding that their parts suppliers provide additional functionality, increased reliability, improved quality and technical advances in parts being supplied while at the same time providing these parts at lower costs. This has placed a significant amount of pressure and burden on suppliers.  
           [0004]    Due to the operating conditions that an automobile or other vehicle is subjected to, many of the parts and subsystems are required to be very robust in order to operate in these conditions. For example, the engine compartment of an automobile is subjected to extremes in temperature (from −60° C. to upwards of a 150° C.), significant amounts of humidity and moisture either through precipitation or water splashing, salt and other corrosive substances and significant mechanical forces as the vehicle moves at high speed while impacting significant road hazards such as pot holes, frost heaves, speed bumps and the like. Other areas of the vehicle, which may similarly be exposed to the elements are often subjected to the same or similarly difficult environmental conditions. Despite these conditions, operators of these vehicles demand that the components operating within are efficient, long-lived and reliable. Moreover, customers and regulators are demanding that, in the event that one or more of these components fail, the operator should either be warned of the failure and/or be enabled to safely shut down the vehicle. As a result of these demands, some systems are designed to have built in redundancies or fail-safe mechanisms.  
           [0005]    For example, the hood of a vehicle normally has two separate devices operating independently to ensure that the hood remains in a closed or latched position during operation. Should the first or main latch fail, a secondary or safety latch is designed to keep the hood in a closed or near-closed position. The secondary latch is designed to prevent the hood of the vehicle from being forced, by a result of significant aerodynamic drag, into the windshield thus preventing significant injury to the vehicle occupants and allowing the operator of the vehicle to have an unobstructed view of the road despite the failure of the first latching mechanism. This particular system has worked exceedingly well in preventing the unsafe operation or an unsafe condition during operation from occurring. In fact, this system has operated so effectively that many drivers or occupants are simply unaware of when the hood is open or being maintained in a near-closed position by the secondary or safety latch. Accordingly, there has developed a need to warn the operator of a vehicle of this unsafe near-closed condition. To satisfy this need, warning instrumentation has been developed to warn a user (usually by way of a warning light or lamp—sometimes derisively referred to the industry as an “idiot light”) of this condition. However, the automotive switches known to the inventors that have been employed to identify the condition of an open or near-closed hood or the failure of the primary hood latch mechanism, have been unsatisfactory for a variety of reasons.  
           [0006]    Amongst these reasons are the known high defect rate in the manufacture of these automotive switches, their propensity to fail due to the harsh conditions experienced in the underhood environment, the switch&#39;s inability to provide any suitable diagnostic indicators to assist in diagnosing whether a warning light has been illuminated as an indicator of a hood open or latch failure condition or an indicator that the switch itself has failed. Accordingly, it would be desirable to provide an automotive switch that addresses some or all of these shortcomings.  
           [0007]    Many operators or owners of vehicles have commenced demanding greater degrees of convenience and usability in their vehicles. One such demand is the ability to provide features and functions related to comfort, especially for vehicles operated in harsh environments (e.g., in extremely hot or humid environmental conditions or extremely cold environmental conditions). For example, owners or operators of vehicles in extreme temperature conditions have begun demanding that their vehicles provide the ability to be remotely started so that the environmental controls (e.g., heating, ventilation and air conditioning systems) can be operated thus heating or cooling the vehicle, as appropriate, prior to the owner or operator entering the vehicle. This features provides enhanced usability and operator comfort. However, while providing remote starting capability is known in the art, such capability should be prevented in the event that the hood is in an open position or the primary hood latch has either failed or is not engaged. Accordingly, an automotive switch which is suitable for such a purpose while addressing some or all of the shortcoming of the switches known to these inventors, is desirable.  
           [0008]    It would be further desirable that such an automotive switch for other latching mechanisms in vehicles (e.g., rear hatches, deck or trunk latches, door latches and other compartment latches) be provided.  
         SUMMARY OF THE INVENTION  
         [0009]    The switch of the present invention is designed to detect the position of a latch (e.g., a fork bolt or ratchet) in vehicle. Specifically, a switch is described and claimed which emits a signal indicative of the position of a latch mechanism. In a further aspect of the invention, the switch is in direct engagement with the associated latch (or portion thereof). In a further feature of the present invention, a switch is described and claimed wherein a switch is adapted to emit a signal that provides diagnostic information of the switch and/or the latch to which the switch is associated. In a further aspect of the invention there is provided a switch that in most circumstances will, in the event of a failure of a switch but not of the latching mechanism, emit a signal indicative of this switch failure thus preventing potentially significant repercussions.  
           [0010]    In one aspect of the present invention there is provided a latching mechanism switch comprising: an enclosure; a switching device fixedly mounted within said enclosure; and a cam rotatably mounted to said enclosure, said cam for direct engagement with an associated latching mechanism and said cam having a magnet fixedly mounted thereto, wherein rotation of said cam and said magnet from a first position to a second position causes said switching device to change from an open state to a closed state and wherein rotation of said cam and said magnet from said second position to said first position causes said first switching to change from said closed state to said open state.  
           [0011]    In a further aspect of the present invention there is provided a method of operating a latching mechanism switch, said method comprising: directly engaging a portion of said latching mechanism switch with a portion of an associated latching mechanism; and moving said latching mechanism from a first, unlatched position to a second, latched position causes a first reed switch of said latching mechanism switch to change from an open state to a closed state, and wherein moving said latching mechanism from said second position to said first position causes said first reed switch to change from said closed state to said open state.  
           [0012]    In a still further aspect of the present invention there is provided a vehicle comprising a latching mechanism and a latching mechanism switch, said latching mechanism switch associated with said latching mechanism, said latching mechanism switch comprising: an enclosure; a first reed switch fixedly mounted within said enclosure; and a cam rotatably mounted within said enclosure, said cam for direct engagement with said associated latching mechanism and said cam having a magnet fixedly mounted thereto, wherein rotation of said cam and said magnet from a first position to a second position causes said first reed switch to change from an open state to a closed state and wherein rotation of said cam and said magnet from said second position to said first position causes said first reed switch to change from said closed state to said open state.  
           [0013]    Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon the review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    In the figures which illustrate exemplary embodiments of the present invention, the following drawings are provided:  
         [0015]    [0015]FIG. 1 schematically illustrates aspects of the invention in relation to a fork bolt;  
         [0016]    [0016]FIG. 2 illustrates, in a different orientation, the switch of FIG. 1;  
         [0017]    [0017]FIG. 3 illustrates a portion of the switch shown in FIGS. 1 and 2 from a different view;  
         [0018]    [0018]FIG. 4 illustrates the switch of FIG. 3 in a different view;  
         [0019]    [0019]FIG. 5 illustrates a semi-transparent view a portion of the switch of FIGS.  1  to  4 ;  
         [0020]    [0020]FIG. 6 illustrates in greater detail aspects of FIG. 5;  
         [0021]    [0021]FIG. 7 illustrates additional portions of the switch of FIG. 5;  
         [0022]    [0022]FIG. 8 illustrates in greater detail aspects of the invention shown in FIG. 5;  
         [0023]    [0023]FIG. 9 illustrates in greater detail portions of the embodiment illustrated in FIG. 5;  
         [0024]    [0024]FIG. 10 illustrates still other portions of the embodiment illustrated in FIG. 5;  
         [0025]    [0025]FIG. 11 illustrates a second embodiment of the invention;  
         [0026]    [0026]FIG. 12 illustrates in greater detail portions of the embodiment of FIG. 11;  
         [0027]    [0027]FIG. 13 illustrates in greater detail portions of the embodiment illustrated in FIG. 12;  
         [0028]    [0028]FIG. 14 illustrates interior portions of the embodiment illustrated in FIGS. 11 through 13;  
         [0029]    [0029]FIG. 15 illustrates in greater detail a first wiring embodiment of the embodiment illustrated in FIGS. 11 through 14;  
         [0030]    [0030]FIG. 16 illustrates a second embodiment of the wiring of the embodiment to the invention illustrated in FIGS. 11 through 14;  
         [0031]    [0031]FIG. 17 illustrates in greater detail portions of the invention illustrated in FIG. 14; and  
         [0032]    [0032]FIG. 18 illustrates aspects of the invention in greater detail illustrated in FIG. 16. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    In overview, the embodiments described herein provide a description of a switch for mounting in the underhood environment to provide a fail-safe automotive switch that operates in conjunction with a hood latch mechanism. As persons of ordinary skill in the art will appreciate, the fail-safe switch described herein will, in most circumstances, provide for a signal to be emitted indicative of a failure of the switch itself or of the latch mechanism with which it is associated. Further, and as persons of ordinary skill in the art will appreciate, the embodiments of the switch described herein could equally be used in other environments such as the latching mechanisms that are employed for other enclosures such as the trunk or deck, tailgates, hatches, compartments and doors.  
         [0034]    Referring to FIG. 1, an embodiment of the inventive switch described herein is generally identified as switch  100 . Switch  100  works in conjunction with fork bolt  106 , which forms part of a hood latching mechanism. That is, switch  100  is associated with a hood latching mechanism. In the exemplary embodiment, this association between switch  100  and the latching mechanism is achieved through mounting switch  100  to fork bolt  106 . In alternative embodiments, a switch embodying aspects of the present invention may be mounted in close proximity to the associated latching mechanism. For example, the switch may be mounted to some part of the vehicle in a position that results in the operation of the switch when the associated latching mechanism is operated.  
         [0035]    Again referencing FIG. 1, included in switch  100  is switch actuator  102  that is directly engaged with fork bolt  106 . That is, the switch actuator  102  is directly coupled and physically interfaces with fork bolt  106 . Switch actuator  102 , as described in greater detail below, is positively biased against one or more portions of fork bolt  106 . As such, by movement of fork bolt  106  (such as the rotation of fork bolt  106  about fork bolt post  108  from an unlatched to a latched position), switch actuator  102  will similarly be translated (or in the exemplary case rotated) from a first position  102   a  (illustrated in FIG. 4) to a second position  102   b  (shown in dotted line in FIG. 4). Switch actuator  102  may be directly coupled to the fork bolt  106  simply through a biasing mechanism or, in addition, may be adhered to fork bolt  106  through the use of adhesives, welding or any other suitable fixture device or mechanism. In switches known to the inventors, fork bolt  106  is indirectly coupled to switch actuator  102  by way of a coil spring.  
         [0036]    Also shown in FIG. 1 is a connector or wiring harness  104  through which electrical or other connection signals (e.g., optics) are transmitted between switch  100  and the control system of the associated vehicles.  
         [0037]    In the present invention, switch actuator  102  is translated through operation of fork bolt  106  through a path that is defined by actuator groove  110 . As a result of the inclusion of groove  110 , the interior of switch  100  is exposed to the elements (e.g., water, salt, etc.).  
         [0038]    In the embodiment of the present invention illustrated in FIGS. 1 and 2, switch actuator  102  is directly coupled to, and in direct connection with, fork bolt  106 . Consequently, although the interior of the switch  100  is exposed to the elements as a result of the actuator groove  110 , this exposure, in most circumstances and unlike switches known to the inventors, will not result in failure of the switch  100 . For example, switches known to the inventors, as a result of being exposed to the elements and being indirectly coupled to fork bolt  106  by way of a coil or other type of spring, will often be filled with precipitation such as snow or rain. This precipitation will often freeze forming significant amounts of ice in the interior of the known switches. As a result of this ice build-up in the switches known to the inventors, if the fork bolt of the hood latch moves from the locked or closed position to the open position (which indicates that either the hood is open or that the hood is partially ajar and maintained in that position by the secondary or emergency latch), the switch actuator of these switches will not move from the closed position to the failure warning position as a result of this build-up. That is, the ice build-up within the switches known to the inventors, as a consequence of ice build-up between the coils of the extended spring, will result in the spring being unable to recoil to its non-extended position. Consequently, in these switches known to the inventors, an operator of a vehicle will not be warned of this potentially dangerous situation. Similarly, if the hood is slightly ajar or even open, the engine could be started remotely which could lead to a potentially dangerous situation if there is someone working on or in the engine compartment.  
         [0039]    In contrast to those switches known to the inventors and despite the existence of the actuator groove  110  exposing the interior of switch  100  to the elements (which may also result in ice build-up), the direct coupling of fork bolt  106  with actuator  102  will result in any ice being broken or cleared through the application of significant forces to fork bolt  106  (in order for it to move from the latched to unlatched or ajar position) being transferred to switch actuator  102 . That is, as fork bolt  106  is rotated about fork bolt post  108 , it will apply force directly against switch actuator  102 . This force, in most circumstances, is sufficient to clear any ice that has built up within the interior of switch  100 .  
         [0040]    Referencing FIG. 2, switch  100  includes a base substrate  204  and a cover  202  which, through operation of snap assemblies  206 , are coupled to form an enclosure which houses most of the components of automotive switch  100 . Cover  202  includes, in the exemplary embodiment, fork bolt post  108  about which fork bolt  106  rotates. Also, cover  202  includes a void that forms groove  110  which guides switch actuator  102  as it rotates or translates. That is, switch actuator  102  is positioned such that, as it translates from the position indicating that the fork bolt  106  is in a closed position  102   a  (also referred to herein as the “fail-safe position”) to position  102   b  (shown in dotted outline in FIG. 4 and referred to herein as the latched or closed position) it is guided by groove  110 .  
         [0041]    In the exemplary embodiment cover  202  includes flexible biasing ribs which extend from a position proximate to a bottom edge of the cover each terminating in a fish-hook style wing, thus forming one-half of snap assemblies  206 . Base substrate  204 , which interacts with cover  202 , includes suitably shaped fish-hook wing receiving apertures  208  which receive the fish-hook style wings. That is, by positioning and pressing cover  202  against base substrate  204 , cover  202  and base substrate  204  can be removably fixed to one another. Initially, the flexible biasing ribs of the snap assemblies will be pushed towards the interior of switch  100  and then, as the fish-hook style wings are advanced towards the receiving apertures  208 , the biasing ribs will force the wings outwards thus forming a mechanical fixture such that base substrate  204  and cover  202  form a fixed enclosure.  
         [0042]    The use of snap assemblies  206  to form the enclosure of switch  100  requires generally very little force and transmits very little force or vibration to the interior components of switch  100 . In distinct contrast, the switches known to the inventors use ultrasonic welding to fix the cover to the base substrate. However, since ultrasonic welding results in subjecting the base and cover to high frequency vibrations, the interior mechanisms (most notably the electrical components) are similarly subjected to these high frequency vibrations. These high frequency vibrations often result in damage to the electrical components or defects in the connections between these electrical components. Accordingly, the switches known to the inventors often have a high defect rate when manufactured. Consequently, this high defect rate increases the overall unit cost of those switches which, at the time of manufacturing, do not have any defects. Also, while the high frequency vibrations do not always result in damage to the interior components to the point of failure, these interior components are often sufficiently damaged such that the overall life expectancy of the switch is significantly degraded. Accordingly, the switches often fail when in operation resulting in increased maintenance costs to either the consumer or the manufacturer of the vehicle. Additionally, due to these defects, the consumer may be given the impression that the overall quality of the vehicle is sub-standard. These effects—the increased unit cost of manufacture, the increased costs associated with repair or warranty work and the decrease in perceived quality by the owner or operator of the vehicle—are simply unacceptable to vehicle manufacturers. The automotive switch described herein has notably reduced rates of defect during manufacture, an improved life expectancy and a greater level of quality may be perceived.  
         [0043]    Referencing FIGS.  1 - 4 , switch  100  in the exemplary embodiment is shown with a connector style wiring housing  104  that includes three terminals. Alternative embodiments may include a lesser or greater number of terminals or alternative styles of wiring housing  104 .  
         [0044]    Referring to FIGS. 5 and 6, the interior mechanism of switch  100  and its operation and interaction is shown in greater detail. In FIG. 5, switch actuator  102  is fixedly mounted to cam  506  that rotates about camshaft or post  602  (FIG. 6). In the exemplary embodiment, switch actuator  102  is fixedly mounted to cam  506  as a result of cam  506  be moulded or formed to include switch actuator  102 . Additionally, a pre-tensioned helical spring is being coiled about spring tension recess or ridges  904  (see FIG. 9) which forms part of cam  506 .  
         [0045]    One end of helical spring  502  is fixed within a slot or channel (locking recess  508 ) forming part of cam  506  while the other end of helical spring  502  is positioned fixed relative to cover  202 . The fixation of portions of spring  502  relative to cam  506  and cover  202  is achieved through the pre-tensioning of spring  502  and the placing of ends of spring  502  into recess  504 . That is, recesses  508  and  504 . As a result of the pre-tensioning of spring  502 , the ends of spring  502  are biased against the interior of recesses  508  and  504  thus holding one end of the spring in a fixed position relative to cover  202  and the other end in a position fixed relative to cam  506 .  
         [0046]    As will be appreciated by those of ordinary skill in the art, other devices which bias cam  506  towards the fail-safe position could be used instead of helical spring  502 . For example, leaf springs, compression springs, torsion springs and other biasing mechanisms could be employed in alternative embodiments.  
         [0047]    Magnet  604  is fixed into a position relative to cam  506 . In the exemplary embodiment, magnet  604  is a disc magnet snap-fitted into this fixed position relative to cam  506 . Alternative shapes of magnet  604  and alternative fixation mechanisms could be equally employed to place magnet  604  in a fixed position relative to cam  506 .  
         [0048]    In FIG. 6, cam  506  and magnet  604  are shown in the fail-safe position  102   a . In this position, switch actuator  102  is in the upper portion of groove  110  and helical spring  502  will be in a relatively low energy state.  
         [0049]    When fork bolt  106  is in the latched or closed position  102   b  (shown in dotted outline in FIG. 4), helical spring  502  will be in a relatively high energy state (i.e., in a relatively unsprung position). That is, helical spring  502  will have been further tensioned as a result of cam  506  being rotated as fork bolt  106  moves to its closed or latched position. As fork bolt  106  is moved from an open/unlatched or fail-safe position to a latched position, this movement forces switch actuator  102  to rotate, in FIG. 6, counter-clockwise to the lowermost position of groove  110 . Such movement causes cam  506 , which is fixably connected to actuator  102 , to be also rotated about camshaft  602  in a counterclockwise direction. This movement of cam  506  also causes magnet  604  to move in a counterclockwise direction while simultaneously tensioning (i.e. adding energy to) helical spring  502 .  
         [0050]    In the rare occurrence that switch actuator  102  is somehow damaged such that switch actuator  102  is no longer directly connected or coupled to fork bolt  102  (this may occur if switch actuator  102  is sheared off of cam  506  as a result of fatigue or other material failure), helical spring  502  will operate to rotate cam  506  (and thus magnet  604 ) from the position indicating that the associated latch is closed to the fail-safe position  102   a  indicated in FIG. 6. In this fail-safe position, an electrical signal would be emitted by switch  102  to indicate to the operator of the vehicle (such as through the illumination of a warning lamp or light) that there is some problem associated with either the hood latch or the switch itself.  
         [0051]    Referencing FIG. 7, switch  100  includes conductors  702  that are, in exemplary embodiment, copper conductors that have been stamped into a specific shape to provide the necessary electrical connection to a connector  104 .  
         [0052]    Switches known to the inventors feature a printed circuit board (PCB) which connects a connector or wiring harness to the interior reed switches and resistors by way of PCB mounted connectors. These PCB mounted connectors typically are pin-through-hole or surface mounted connectors. Distinctively, the preferred embodiment includes conductors that are fashioned into a specific shape and then encapsulated in suitable material such as, for example, the materials described below. The inventors have realized that a PCB-based circuit impinges upon the ability to properly package the mechanisms necessary for the operation of the switch often resulting in a less than optimal mechanism design, arrangement or an overall increase in the size. In distinct contrast, the preferred embodiment includes conductors which can be fashioned into nearly any shape (unlike a PCB which, due to the environmental conditions in which the switch and PCB operate, needs to be relatively planar and mechanically robust).  
         [0053]    In the embodiment illustrated in FIG. 7, the copper conductors  702  have been stamped into a complex three dimensional shape connecting the reed switches (illustrated as reed switches  704  in FIG. 7) to connector  104 . The conductors  702  are, during the manufacturing process, encapsulated in suitable material thus providing both electrical insulation while at the same time providing protection and an improved level of reliability and longevity of switch  100 .  
         [0054]    Reed switches  704  (in the exemplary embodiment illustrated in FIG. 7, reed switches  704 A and  704 B) are conventional sealed switches and include contacts in a hermetically sealed glass tube filled with a protective gas. While reed switches  704  are generally considered to be fairly robust. However, the inventors of the present invention have identified that reed switches exposed to the vibrations of ultrasonic welding (such a process being used in the manufacturing of switches known to the inventors) vibrations often render such reed switches completely inoperative or result in damage the switches. The extent of this damage is often of a level of severity that impacts the longevity and durability of the entire switch when the switch is stressed by the environmental conditions in which vehicles operate. Consequently, the damage to the reed switches caused by ultrasonic welding often causes early failure of reed switches  704  and the switch as a whole.  
         [0055]    As will be appreciated by those of ordinary skill the art, reed switches  704  could be replaced, in alternative embodiments, with other switching devices. These other switching devices could leverage mechanical properties or electromagnetic properties (a reed switch leverages electromagnetic properties). For example, cam  506  could be used to toggle a microswitch between the on and off states. Alternatively, a sliding contact switch could also be employed. Also, if desired, alternative embodiments of the present invention may employ Hall effect switch(es) in place of the reed switch(es). Other switching devices could also be employed in further alternative embodiments.  
         [0056]    In the exemplary embodiment, in addition to the use of snap assemblies  206  which prevents such vibratory damage, reed switches  704  and conductors  702  are encapsulated in a suitable material which provides additional and enhanced protection of reed switches  704  and conductors  702 . The encapsulation process improves the overall durability and reliability of switch  100 .  
         [0057]    In the exemplary embodiment, the encapsulation or potting of these components uses of a two-part epoxy or a thermoplastic elastomer. In one embodiment Hysole® potting compound (available from Loctite Corporation of the U.S.) is employed. In a different embodiment, thermoplastic polymer—Techbond® 6700-65, a styrenic block copolymer from Teknor Apex Company of Pawtucket, R.I.—is employed. Both of these potting compounds provide additional and enhanced protection of reed switches  704  while displaying the physical properties desirable for mounting of the associated switch in a vehicle&#39;s engine compartment.  
         [0058]    Referencing FIGS. 9 and 10, cam  506 , incorporating switch actuator  102 , also includes a camshaft or post sleeve  902  which is sized and arranged to slide onto camshaft  602  (shown in FIGS.  6 - 8 ) thus enabling cam  506  to smoothly rotate about camshaft  602 . Additionally, to further stabilize and secure cam  506  within the confines of cover  202  and a base substrate  204  (FIG. 2). Base substrate  204  includes a circular cavity  1002  to secure cam  506  in a fixed lateral and longitudinal position within the confines of switch  100 . Circular cavity  1002  is shaped to allow for the relatively smooth rotation of cam  506  about the axis defined by camshaft  602  (FIGS.  6 - 8 ). Further, circular cavity  1002  is adapted to receive the terminating end of camshaft  602  when cover  202  and base substrate  204  are snapped into position through operation of snap assemblies  206 . As a result of the interaction between cover  202 , base substrate  204 , snap assemblies  206 , camshaft  602  and circular cavity  1002 , cam  506  is longitudinally and laterally fixed within switch  100  but allowed to freely rotate (within the limits defined by the movement of switch actuator  102  within actuator groove  110 ) about camshaft  602 .  
         [0059]    The manufacturing operation of switch  100  will be better understood with particular reference to FIGS. 1, 2,  4 ,  6 ,  7 ,  8 ,  9  and  10 . The base substrate  204  receives reed switches  704 A and  704 B and connector  104 . Conductors  702  are stamped and arranged to electrically connect reed switches  704  to the electrical connections of connector  104 . Thereafter, conductors  702  and reed switches  704  are encapsulated in a suitable encapsulation material such as a two part epoxy or thermoplastic elastomer.  
         [0060]    With reference to FIGS. 8 and 9, magnet  604  is fixedly mounted to cam  506 . Additionally, one end of helical spring  502  is received by locking recess  508  that forms part of cam  506 . Spring  502  is pre-tensioned and placed within spring-tensioning recess  504  that is substantially concentric about camshaft sleeve  902 . Cam  506 , incorporating magnet  604  and spring  502 , slides onto camshaft  602  that forms part of cover  202 . Additionally, cam  506  is positioned about camshaft  602  such that spring terminus  906  (shown in FIG. 9) is received by spring locking recess  504  which forms part of cover  202 . Still further, cam  506  is positioned about camshaft  602  in a manner that switch actuator  102  is positioned within actuator groove  110  of cover  202 . As a result of the positioning of cam  506  relative to cover  202 , switch actuator  102  will be positioned at its fail-safe position—illustrated as position  102   a  in FIG. 4.  
         [0061]    Cover  202  is then brought into a position proximate to base substrate  204  and these two components are forced together and locked into a relatively fixed position through operation of snap assemblies  206 . During this procedure, the upper portion of cam  602  and camshaft sleeve  902  will be positioned within the interior of circular cavity  1002  of base substrate  204  thus providing additional strength and rigidity to switch  102  and the components therein. Additionally, as a result of the use of snap assemblies  206 , switch  100  can be quickly disassembled, inspected and/or repaired and re-assembled without any special tools or processes.  
         [0062]    Still referencing FIGS. 1, 2,  4 ,  5 ,  6 ,  7  and  8 , switch  100 , prior to installation within a vehicle, will have switch actuator  102 , in the fail-safe position  102   a  illustrated in FIG. 4. In this fail-safe position, magnet  604  will be positioned relative to reed switches  704 A and  704 B are in a closed position. Accordingly, as a result of the contacts within reed switches  704 A and  704 B being closed, the equivalent resistance for the circuit will be a function of the resistance of reed switches  704 A and  704 B. That is, the equivalent resistance of the circuit wherein magnet  604  has closed the contacts of both reed switches  704 A and  704 B will be defined by the formula below (where R 1  and R 2  are the resistance of reed switches  704 A and  704 B, respectively, and R p  is the equivalent resistance for the entire circuit):  
         R   p     =         R   1     ·     R   2           R   1     +     R   2                               
 
         [0063]    If it is detected that the resistance exhibited by automotive switch  100  is the result of the contacts of both reed switches  704  being in the closed position (i.e., in conformity with the above equation), the diagnostics of the vehicle into which switch  100  has been installed, will operate to turn on the appropriate indicator lamp. This indicator lamp is viewable by the driver of the vehicle and provides a warning that the hood is possibly in an unlatched and dangerous position. Additionally, circuitry within the vehicle will disable any remote-starting device within the vehicle. Accordingly, if the vehicle is not in operation, but the fail-safe switch  100  indicates that the hood latch is open, a person attempting to remote start the vehicle will be prevented from doing so. In the event that the vehicle is operating (whether idling or in motion), an indicator light will be turned on warning an occupant or a driver that the hood (or other door, hatch or tailgate with which the switch is associated) is in an unlatched and unsafe position.  
         [0064]    During installation of switch  100  into a vehicle, switch  100  will be positioned and mounted to a latching mechanism such as a fork bolt  106  (shown in FIGS. 1 and 2). The latching mechanism, such as fork bolt  106 , will be placed in direct contact with switch actuator  102 . Also, switch  100  will be positioned relative to fork bolt  106  such that the rotation (in either direction) of fork bolt  106  (which is shown in the unlatched position in FIG. 1) will result in fork bolt  106  being rotated about the axis defined fork bolt post  108 . Consequently, fork bolt  106 , during a hood closing operation, will force switch actuator  102  from the fail-safe position  102   a  (illustrated in FIG. 4) to the latched position  102   b  (shown in dotted outline in FIG. 4). Resulting from the movement of switch actuator  102  from fail-safe position  102   a  to latched position  102   b  by switch actuator  110 , cam  506  and magnet  604  fixed thereto will be similarly rotated about camshaft  602 . Magnet  604  will be rotated to a position where the magnetic field applied to the contacts within reed switches  704  is sufficiently weakened such that the contacts within reed switches  704  are separated. This separation of the contacts will significantly reduce or eliminate the flow of electric current through reed switches  704 . As a result of the change in the operation of reed switches  704 , a vehicle&#39;s control system will effectively measure a very high or infinite level of resistance exhibited by the circuitry of switch  100 . This level of resistance will indicate that the associated hood is closed or in a safe position. Accordingly, any warning lamp previously illuminated within the vehicle can be turned off.  
         [0065]    As will be apparent to those of ordinary skill in the art, during normal operation of switch  100 , the circuitry of switch  100  will exhibit to the control systems of the associated vehicle either a very high or near infinite resistance or resistance described above when the contacts of reed switch  704  are closed. A near infinite resistance indicates that the associate fork bolt and hood (or door, tailgate or the like) are in the closed or safe position. If a vehicle&#39;s control system measures the resistance exhibited by switch  100  to be equal to the resistance of a parallel circuit having both reed switches  704 A and  704 B in a closed (i.e., conducting) position, this resistance is indicative of the hood latch being in an unsafe position. Accordingly, the vehicle&#39;s control system will illuminate the required warning lamp warning an operator of the vehicle of the potentially dangerous situation.  
         [0066]    In the event that there is a failure of switch actuator  102 , cam  506  and, thus magnet  604 , will, in most circumstances, move from a position indicating a safe position (reed switches  704  are open) to the fail-safe position (reed switches  704  are closed) indicating an unsafe or unlatched position of the associated hood, door or the like. For example, consider, due to material fatigue or other physical phenomena, switch actuator  102  is sheared from cam  506 . In this instance, the rotation of fork bolt  106  will not apply any forces to cam  506  nor prevent the rotation of cam  506  about camshaft  602 . However, if helical spring  502  is in the (relatively) high-tensioned state of closed position  102   b  (as compared to fail-safe position  102   a ), helical spring  502  will operate to apply a force to cam  506  to rotate cam  506  and magnet  604  from the latched position to the fail-safe position. Accordingly, even though the associated hood may in fact be closed and in a safe position, an operator of a vehicle will be, through the illumination of a warning lamp, warned of a potentially unsafe position. This will provide a warning to the operator of the vehicle to have the vehicle and, more particularly, the latching mechanism including switch  100 , inspected and repaired. Additionally, and as noted above, the fail-safe position of switch  100  would prevent the remote-starting of the vehicle.  
         [0067]    If switch  100  has been damaged or fails to operate properly such that it is neither in the fail-safe position (illustrated as position  102   a  in FIG. 4 of switch actuator  100 ) nor in the unlatched or unsafe position (illustrated as position  102   b  in FIG. 4), but in some intermediate position, switch  100  will exhibit a level of electrical resistance that is neither extremely high or near infinite (as is the case when the contact of both reed switches  704  are in the separated position) or the level of resistance to both reed switches  704  being closed. In this case, diagnostic equipment (which may form part of a vehicle&#39;s onboard control system or be a separate device) will be able to measure such an intermediate level of resistance and, noting this intermediate resistance level, assist in the diagnosis that a failure to switch  100  may have occurred.  
         [0068]    Alternative embodiments of the embodiment of the invention illustrated in FIGS.  1  to  10  are illustrated in FIGS. 11 through 18.  
         [0069]    In the automotive switch  100 ′ illustrated in FIG. 11, switch actuator  102 ′, rather than protruding through the primary surface of the base substrate as with the previous embodiment, protrudes from the side of the enclosure defined by base substrate  204 ′ and cover  202 ′. Actuator  102 ′ can be moved through either a rotating latch mechanism or a translating mechanism (neither of which are illustrated). Also, rather using the connector of the previous embodiment, switch  100 ′ of FIG. 11 includes a wiring harness  104 ′. Further, base substrate  204 ′ includes optional screw or fastener receptacle  1204  which is used to receive a screw, rivet or other fastener for mounting switch  100 ′ to a latch. Additionally, switch  100 ′ includes anti-rotation pins  1202  that ensure that switch  100  does not rotate relative to the latch to which it is mounted.  
         [0070]    Referencing FIG. 14, the interior of switch  100 ′ is illustrated. Similar to the first embodiment illustrated in FIGS. 1 through 10, alternative embodiment of switch  100 ′ includes a cam  506 ′ (that is rotatably mounted on camshaft  602 ′) and magnet  604 ′ fixed to cam  506 ′. As with switch  100 , switch  100 ′ also includes a helical spring  502 ′ with one end of the spring biased against a fixing barrier  1406  and the other end biased against cam  506 ′. The end biased of spring  502 ′ biased against cam  506 ′ is mounted within and hooks through spring groove  1404 . As cam  506 ′ rotates about camshaft  602 ′ from a position shown in FIG. 14 (the fail-safe position) to position  1408  (indicated by dotted line in FIG. 14), spring  502 ′ will store additional energy. Additionally, the end of helical spring  502 ′ biased against the interior of spring groove  1404  will translate or move within the groove. The rotation from the fail-safe position to the latched position  1408  of cam  506 ′ will result in the movement of magnet  604 ′. As a result of this movement of magnet  604 ′ from the fail-safe position to the latched position  1408 , the connectors of reed switches  704 A and  704 B moved from a state of contact to a state of separation. In FIG. 17, magnet  604 ′ has been insert moulded directly into cam  506 ′ thus fixing magnet  604 ′ to cam  506 ′ with a very high degree of reliability and longevity.  
         [0071]    Similar to switch  100 , switch  100 ′ also incorporates moulding or encapsulation material  1402  that protects electrical connection and reed switches  704  in extreme moisture conditions while providing additional reliability.  
         [0072]    [0072]FIG. 15 illustrates a further alternative embodiment of the present invention. In the alternative switch  100 ″ illustrated in FIG. 15, the dual reed switch circuitry of the previous embodiments is replaced with a double resistor ( 1502 A and  1502 B), single reed switch  704 ″ configuration. In this embodiment, switch  100 ″ does not include the ability to provide the advanced diagnostic feature (wherein an intermediate level of circuitry resistance indicates a condition of a first reed switch in the open condition and the second reed switch being closed) of the previous embodiments.  
         [0073]    [0073]FIG. 16 illustrates a still further alternative embodiment of the present invention. Switch  100 ′″ illustrated in FIG. 16 a triple wire wiring harness  104 ′″ is employed with the dual reed switch circuitry (which was employed in embodiments  100  and  100 ′). In FIG. 17, magnet  604 ′″. Switch  100 ′″ also includes insert moulded directly into base substrate  204 ′″ which provides enhanced reliability of switch  100 ′″.  
         [0074]    While the switches illustrated in FIGS.  1 - 16  have been described as resulting in a warning lamp being illuminated when one or more of the reed switches are in closed state and deactivate or turn off the warning lamp when the reed switch(es) are in the open state, alternative embodiments could, for example, illuminate the warning lamp when the reed switch(es) is(are) in the open state and deactivate the warning lamp when the reed switch(es) is(are) in the closed state.  
         [0075]    In a further alternative embodiment of the present invention, a portion of the latching mechanism (e.g., the fork bolt) could effectively replace the cam in the switches heretofore. That is, a portion of the latching mechanism effectively acts as the cam. In this alternative embodiment, a magnet would be fixed (e.g., attached, embedded within, etc.) relative to the latching mechanism portion. The movement of this portion (e.g., the movement of the fork bolt) would then result in the movement of the magnet to a position which would cause the reed switches to switch state (i.e., change from open to closed, or vice versa).  
         [0076]    While the above detailed description has shown, described, and pointed out the fundamental novel features of the invention as applied to various embodiments, it will be understood that various omissions and substitutions and changes in the form and details of the system illustrated may be made by those skilled in the art, without departing from the intent of the invention.

Summary:
The switch of the present invention is designed to detect the position of a latch (e.g., a fork bolt or ratchet) in a vehicle. Specifically, a switch is described and claimed which emits a signal indicative of the position of a latch mechanism. In a further aspect of the invention, the switch is in direct engagement with the associated latch (or portion thereof). In a further feature of the present invention, a switch is described and claimed wherein a switch is adapted to emit a signal that provides diagnostic information of the switch and/or the latch to which the switch is associated. In a further aspect of the invention there is provided a switch that in most circumstances will, in the event of a failure of a switch but not of the latching mechanism, emit a signal indicative of this switch failure thus preventing potentially significant repercussions.