BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to lighting systems and, more particularly, relates to an exit light control system configured to illuminate an operator&#39;s way during departure from an off-road vehicle. The invention additionally relates to an off-road vehicle, such as an agricultural combine, incorporating such an exit light control system, and to a method of operating such an exit light control system.  
           [0003]    2. Background of the Invention  
           [0004]    Most off-road vehicles incorporate lighting systems enabling them to be operated at night. For example, backhoes, bulldozers, tractors, and combines all incorporate a system of running lights that illuminate the areas in front, behind, and/or beside the vehicle. Most of these vehicles are controlled by an operator seated in a station located a substantial height above the ground. The station typically comprises a platform or a cab accessible via an access ladder extending from the station to the ground.  
           [0005]    Many off-road vehicles incorporate exit light control systems that facilitate an operator&#39;s departure from the vehicle. The typical exit light control system is configured to activate one or more exit lights on the vehicle to illuminate an area adjacent one or both sides of the vehicle for a period of time after the operator “parks” (i.e., turns off) the vehicle and/or the vehicle&#39;s running lights. The exit lights provide a clear line of sight to permit the operator to climb down the access ladder and to walk away from the vehicle. The exit lights usually comprise side flood lamps located adjacent one or both sides of the vehicle. Exit lighting systems of this type are particularly beneficial in agricultural vehicles, such as tractors and combines, because those vehicles are often parked in the field at night at a substantial distance from the nearest illuminated area. In addition, the operator of this type of vehicle often parks the vehicle in a field or at another location in which he or she is unsure of the characteristics of the ground on which the vehicle is parked. By illuminating the area adjacent the vehicle, the operator can depart the vehicle with confidence that it is safe to do so.  
           [0006]    Known exit light control systems are configured to automatically activate the vehicle&#39;s exit lights. In this type of system, the vehicle&#39;s light switch is coupled to a controller that activates the exit lights for a designated period of time (typically about  30  seconds) when the operator selects an OFF position of the vehicle&#39;s light switch. This type of automatically-triggered system can be a nuisance to an operator who is unfamiliar with it. The unfamiliar operator may turn off the lights, dismount from the vehicle, and begin to walk away from the vehicle before he or she notices that the exit lights are activated. The unsuspecting operator&#39;s natural reaction is to assume that he or she forgot to turn off the running lights and to return to the vehicle to turn off the lights. An operator laboring under this misconception will likely partially or completely finish the return trip to the operator&#39;s station before the exit lights deactivate themselves. The operator then must either reactivate the exit light control system (assuming he or she knows how to do so) or dismount from the vehicle in the dark. Both alternatives are unattractive.  
           [0007]    Another problem associated with the typical exit light control system available today is that the same programmed controller that controls the vehicle&#39;s running lights operates the exit lights. Retrofitting an exit light control system into a vehicle of this type requires reprogramming and/or replacing the existing controller. Neither task is easily performed by unskilled personnel. In addition, exit light control systems of this type cannot be incorporated into vehicles lacking a programmed controller.  
           [0008]    Yet another problem associated with known exit light control systems is that they require that the running lights be activated for at least a period of time before the exit lights are activated. This requirement to operate the lighting controls in a particular sequence undesirably prevents the operator from dismounting from the vehicle without ever activating the running lights. Simply put, the operator lacks an adequate sense of control over the vehicle.  
           [0009]    The need therefore has arisen to provide an exit light control system for an offroad vehicle that gives the vehicle&#39;s operator a sense of control over operation of the vehicle&#39;s exit lights.  
           [0010]    The need also has arisen to provide an exit light control system for an off-road vehicle that can be easily retrofitted into an existing vehicle design or even into an existing vehicle.  
           [0011]    The need has also arisen to provide an improved method of lighting area(s) adjacent an off-road vehicle while an operator dismounts from the vehicle.  
         SUMMARY OF THE INVENTION  
         [0012]    In accordance with a first aspect of the invention, a lighting system for an off-road vehicle includes one or more exit lights that are activated upon operator demand and that are to automatically deactivated a designated period of time after activation, thereby facilitating the operator&#39;s departure from the vehicle. The lighting system includes an electrical power source, at least one running light, at least one exit light, and a control system that is coupled to the power source and to the lights and that controls operation of the running light and the exit light. The control system includes a manually operated switch movable between (1) an OFF position in which neither the running light nor the exit light is coupled to the power source, (2) a running light activation position in which at least the running light is coupled to the power source, and (3) an exit light activation position. A timer is operatively coupled to the switch and to the exit light and is operable, in response to selection of the exit light activation position of the switch, to couple the exit light to the power source for a designated period of time.  
           [0013]    The switch is preferably of standard dimensions, and all exit light control system components are preferably configured to be compatible with an existing running light control system, thereby permitting the control system to be retrofitted into an existing running light control system design by unskilled personnel.  
           [0014]    Preferably, the OFF position of the switch is located between the running light activation position and the exit light activation position in a direction of switch movement. For instance, the switch may be a rocker switch in which the OFF position is a center position, the running light activation position is a first end-depressed position, and the exit light activation position is a second end-depressed position. In order to provide a momentary-on characteristic in its operation, the rocker switch is not latchable in the second-end depressed position but, instead, is biased toward the center position from the second-end depressed position.  
           [0015]    In accordance with another aspect of the invention, a method of facilitating an operator&#39;s departure from an off-road vehicle comprises manually selecting a running light activation position of a switch to activate running lights of an off-road vehicle, manually selecting an exit light activation position of the switch, and, in response to selection of the exit light activation position of the switch, activating an exit light of the vehicle for a designated period of time, and then automatically deactivating the exit light. Because exit light activation occurs under operator control rather than automatically, and because exit light activation is not necessarily preceded by running light deactivation or any other operation, the operator is imbued with a sense of control not experienced with other exit light control systems.  
           [0016]    Preferably, a timer is triggered upon selection of the exit light activation position of the switch to supply electrical power to the exit light for a period of time set by the timer.  
           [0017]    Other objects, features, and advantages of the invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which:  
         [0019]    [0019]FIG. 1 is a somewhat schematic, perspective view of a combine incorporating an exit light control system constructed in accordance with a preferred embodiment of the present invention;  
         [0020]    [0020]FIG. 2 is a front elevation view of a control panel of the combine of FIG. 1 that incorporates a switch of the exit light control system;  
         [0021]    [0021]FIG. 3 is a fragmentary perspective view of a portion of the control panel of FIG. 2; and  
         [0022]    [0022]FIG. 4 is a circuit diagram of the exit light control system.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    1. System Overview  
         [0024]    As discussed above, the inventive exit light control system is usable with a variety of industrial and agricultural vehicles. It is particularly well-suited for use with vehicles that 1) incorporate an operator&#39;s station located a substantial distance above the ground, 2) are often operated at night, and 3) are often parked at locations remote from the nearest illuminated area. Vehicles exhibiting these characteristics include, but are in no way limited to, backhoes, bulldozers, agricultural tractors, and agricultural combines. Hence, while the invention will now be described in conjunction with a combine, it is to be understood that it is usable on a variety of other off-road vehicles as well.  
         [0025]    Referring now to the drawings and initially to FIG. 1 in particular, an agricultural combine  10  is illustrated that incorporates an exit light control system constructed in accordance with a preferred embodiment of the invention. Except for the exit light control system, the combine  10  is at least essentially conventional. It includes a selfpropelled chassis  12  supported on the ground via a pair of relatively large front driving wheels  14  and a pair of relatively small rear steering wheels  16 . A replaceable harvesting head  18  is mounted on the front of the chassis  12  for harvesting the crop of interest. The illustrated harvesting head  18  is a so-called “grain head” configured to harvest soybeans, wheat, oats, or the like. In most combines, the grain head  18  can be replaced with another harvesting head such as a so-called “corn head” configured to detach ears of corn from stalks. The combine  10  is operable to feed the harvested grain from the head  18  to internal thrashers and separators (not shown) that separate the grain from stalks, pods, cobs, etc. (collectively referred to herein as chaff.) A storage hopper  20  stores the harvested grain. Finally, an auger  22 , mounted on top of the combine  10 , conveys the harvested grain to a wagon, another auger, or another storage and/or transfer device or facility. In addition, a chaff spreader (shown generally at  24 ) is located at the rear of the combine  10  for chopping the chaff and/or spreading it on the ground.  
         [0026]    The combine  10  is controlled by an operator stationed in an operator&#39;s station. In the illustrated embodiment, the operator&#39;s station comprises a platform  26  located within a cab  28 . The cab  28  (1) is enclosed by walls including front and side walls  30  and  32 , (2) is covered by a roof  34 , and (3) is accessible via a door (not shown) on the left side of the cab  28 . The cab  28  houses a seat  36 , a steering wheel  38 , and a variety of controls that are accessible by the operator to control all of the combine&#39;s operations. A ladder  40  extends downwardly from the operator&#39;s platform  26  toward the ground at a location near the left front tire  14 . Some combines also incorporate other, less substantial, ladder(s) (not shown) at other locations on the combine  10  to provide access to equipment on those locations for repair, maintenance, etc.  
         [0027]    Running lights  42 ,  44  and flood lamps  46  are mounted on the combine  10  to permit nighttime operation. The running lights typically include at least headlamps  42  and rear lamps  44 . The headlamps  42  are provided in a line extending horizontally across the upper end of the front wall  30  of the cab  28 . They are configured to illuminate the head  18  and the area in front of it. The rear lamps  44  (only one of which is shown) are mounted on the rear end of the combine  10  and illuminate an area behind the combine  10  to permit the operator to monitor the spreading of chaff on the ground and other activities occurring behind the combine. The flood lamps  46 , are mounted on or near the left and right sides of the combine  10  and illuminate areas adjacent those sides.  
         [0028]    2. Construction and Operation of Exit Light Control System  
         [0029]    The lights  42 ,  44 , and  46  are controlled by an exit light control system  48  (FIG. 4). System  48  is configured to activate the running lights  42  and  44  and possibly other lights on the combine  10  during normal nighttime operation and to activate or continue to activate at least one “exit light” for a sufficient period of time after the combine  10  is parked to permit the operator to dismount from the combine  10  and walk away from it. Advantageously, system  48  may also (1) be configured to be usable in lighting systems that do not have programmed controllers and (2) be easily retrofittable into an existing lighting system design and possibly even into an existing vehicle. In the illustrated embodiment, the exit lights that are activated after the vehicle is parked comprise only the side flood lamps  46 . It is conceivable, however, that other lights could be activated at this time in addition to or instead of the flood lamps  46 . For instance, lights could be provided on or very near the ladder  40  to more specifically illuminate the ladder  40  and other areas on and adjacent the operator&#39;s platform  26 . In addition, if the exit light control system  48  were to be used on a tractor or another vehicle having an access latter at the rear of the vehicle, the exit lights would comprise the vehicle&#39;s rear light(s).  
         [0030]    In order to permit the operator to control at least most aspects of the combine&#39;s exterior lighting with a single switch, the exit light control system  48  is controlled by the same switch  50  used to operate the vehicle&#39;s running lights. That switch  50  should be mounted in a location which is readily accessible by the operator seated on the seat  36 . Referring to FIG. 2, a suitable location for the switch  50  is on a control panel  52  mounted on a front headliner  54  of the combine  10 . The front headliner  54  is located on the inside surface of the front wall  30  of the cab  28  at a location just above an operator&#39;s sun visor  56 . The control panel  52  supports a variety of switches, instruments, and other controls in addition to the light switch  50 . For instance, in the illustrated embodiment, the control panel  52  may also support a hazard warning switch  58 , a windshield wiper switch  60 , a radio  62 , environmental controls  64 , etc.  
         [0031]    The switch  50  of the preferred embodiment is movable between an OFF position, a running light activation position, and an exit light activation position. No lighting circuits are activated when the switch&#39;s OFF position is selected. All running lights  42 ,  44  (and possibly the flood lamps  46  as well) are activated when the running light activation position is selected and remain activated for so long as the switch  50  is in its running light activation position. The exit lights are activated when the exit light activation position is selected but are automatically deactivated a designated period of time after that position is selected. This aspect of the system  48  prevents the exit lights from being inadvertently left on for extended periods of time. A variety of multi-way switches are capable of operating in this manner. Dial switches, multi-position toggle switches, and push-button switches are all acceptable. However, a rocker switch is currently preferred.  
         [0032]    Referring now to FIG. 3, one possible rocker switch  50  usable in the control system  48  of FIG. 4 is a three-position rocker switch that is mounted in an access opening in the control panel  52 . For purposes of aesthetics and convenience, the switch  50  can be of the same dimensions as the other switches  58  and  60  on the control panel  52  and located in line with the other switches  58  and  60 . By using a rocker switch of conventional dimensions, the switch  50  can be more easily incorporated into an existing instrument package. Indeed, because most off-road vehicles now employ rocker switches as their light switches, the switch  50  can simply replace the existing light switch in retrofit applications by unskilled personnel. As is conventional in switches of this type, the switch  50  includes a center neutral position, a first end-depressed position obtainable by depressing the switch  50  in the direction of arrow  66  in FIG. 3, and a second enddepressed position obtainable by depressing the switch in the direction of arrow  68  in FIG. 3. The center position corresponds to the OFF position of the switch  50 . The first end-depressed position corresponds to the running light activation position, and the second end-depressed position corresponds to the exit light activation position. In order to meet the desired design criteria discussed in the preceding paragraph, the switch  50  is latchable in either its OFF position or its running light activation positions but is biased from its exit light activation toward its OFF position by an internal spring  70  (FIG. 4).  
         [0033]    The circuitry of the exit light control system  48  may take any of a variety of forms. If the exit light control system is incorporated into a vehicle having a programmed controller, the exit light control functions could simply be programmed into that controller. A hard-wired circuit is preferred in the illustrated embodiment in which the exit light control system is designed for use in a vehicle lacking a programmed controller but having a preexisting lighting control system. Referring to FIG. 4, the preferred hard wired system  48  includes the switch  50 , a timer  72 , and a side flood lamp relay  74 , all of which are coupled to a power source such as a battery  76  via a main supply line or cable  78 . The internal connections of these components and the manner in which they are coupled to one another will now be detailed.  
         [0034]    Still referring to FIG. 4, the switch  50  includes an internal contact  80  that is movable to connect an input terminal  82  to one of first, second, and third output terminals  84 ,  86 ,  88 , depending upon the position of the contact  80 . The input terminal  82  is connected to the cable  78  by a wire  90 . The first or center output terminal  84  corresponds to the neutral or OFF position of the switch  50  and is not connected to any other powered circuits. The second or first end output terminal  86  corresponds to the running light activation position of the switch  50  and is coupled to the running lights  42 ,  44  via a wire  92 . The third or second end output terminal  88  corresponds to the exit light activation position of the switch  50  and is connected to a triggering input terminal  100  of the exit light timer  72  via a wire  94 . If the switch  50  is backlit, a backlight  96  may be provided in the switch  50  and coupled directly to the input and output sides of the switch  50 .  
         [0035]    The exit light timer  72  may comprise any of a variety of settable or non-settable timers that are operable, upon receiving a triggering input signal from the switch  50 , to supply a triggering output signal to another device (in this case the side flood lamp relay  74 ) for a period of time set by the timer  72 . The illustrated timer  72  includes first and second input terminals  98 ,  100 , an output terminal  102 , and a ground terminal  104 . The first input terminal  98  is as driving power input terminal connected to the cable  78  by a wire  106 . The second input terminal  100  is triggering input terminal connected to the third output terminal  88  of the switch  50  via the wire  94 . The output terminal  102  is connected to the side flood lamp relay  74  via a wire  108  as described is greater detail below. Finally, the ground terminal  104  is connected to ground via a ground wire  110 . As is conventional, the timer  72  includes internal circuitry that couples the driving power input terminal  98  to the output terminal  102  for a designated period of time upon receipt of an energizing pulse from the switch  50 . If the side flood lamps  46  are also to be operated with the running lights  42 ,  44 , the output terminal  102  could also be connected to the energizing circuit for the running lights  42 ,  44 , either directly via a connection to the wire  92  or to the terminal  86  or indirectly via intermediate connections.  
         [0036]    The side flood lamp relay  74  is unnecessary in applications in which the side flood lamps  46  are capable of being powered directly by the wire  108 . In the embodiment illustrated in FIG. 4 in which a relay is necessary or at least desired, the relay  74  has first and second input terminals  112  and  114 , first and second output terminals  116  and  118 , and a ground terminal  120 . The first input terminal  112  is permanently supplied with energizing power by a wire  122  coupled to the cable  78  either directly or, as in the illustrated embodiment, by being connected to the driving power terminal  98  of the exit light timer  72 . The second input terminal  114  is connected to the output terminal  102  of the exit light timer  72  by the wire  108 . The first output terminal  116  is a neutral terminal that is not connected to any powered circuit, and the second output terminal  118  is connected to the side flood lamps  46  by a system of wires collectively denoted  124 . The ground terminal  120  is connected to ground via a ground wire  126 .  
         [0037]    The relay  74  is a normally-open relay. It has an electromagnet  128  that is closed when energizing current is supplied to the second input terminal  114  to move a contact  130  (1) from the position illustrated in FIG. 4 in which it connects the first input terminal  112  to the first or neutral output terminal  116  (2) to the non-illustrated position in which it connects the first input terminal  112  to the second output terminal  118  to supply electrical power to the side flood lamps  46 . As is conventional with relays of this type, the contact  130  is biased towards the illustrated position. Hence, when power is no longer supplied to the electromagnet  128 , the contact  130  automatically returns to the position illustrated in FIG. 4 to deactivate the flood lamps  46 .  
         [0038]    In use, when an operator stationed within the cab  28  wishes to activate the combine&#39;s running lights  42 ,  44  for nighttime operation, he or she selects the running light activation position of the switch  50 , thereby coupling the input terminal  82  of the switch to the second output terminal  86  to activate the running lights  42 ,  44 . The switch  50  is latched in that position after the operator releases it. The running lights  42 ,  44  therefore remain activated until the operator again engages the switch  50 . When the operator wishes to park the combine  10 , he or she may deactivate all lights by pressing the switch  50  to its center or OFF position, thereby coupling the input terminal  82  of the switch  50  to the first or neutral output terminal  84  and deactivating all lights. Conversely, the operator may choose to activate the exit lights (the side flood lamps  46  in this embodiment) by depressing the switch  50  beyond its center position to its second-end depressed position, thereby connecting the input terminal  82  to the third output terminal  88 . This operation triggers the exit light timer  72 , thereby tripping the side flood lamp relay  74  to supply electrical power to the side flood lamps  46 . Although the switch  50  returns to its center OFF position under the return force of the internal spring  70  immediately upon operator release of the switch  50 , the relay  74  will remain in its closed position for a period of time designated by the timer  72 . That time period is set to provide the operator with adequate time to exit the cab  28 , climb down the ladder  40 , and walk away from the combine  10  while remaining within the area illuminated by the side flood lamps  46 . Typical time periods are between  15  seconds and one minute, most typically about  30  seconds. At the end of this time period, the timer  72  shuts down to discontinue the supply of electrical power to the relay  74 , thereby deactivating the side flood lamps  46 .  
         [0039]    Due to the design of the exit light control system  48 , the running lights  42 ,  44  need not necessarily be activated before the exit lights are system is activated. The operator could instead simply select the exit light activation position of the switch  50  without ever activating the running lights, in which case the timer  72  would be triggered and the flood lamps  46  would be illuminated for the period of time set by the timer  72 . This versatility instills the operator with a highly-developed sense of control over all major aspects of the operation of the exit light control system  48 . In addition, because the operator must make a conscious decision to activate the side flood lamps forming the exit lights, he or she is not surprised when those lights remain on after he or she dismounts from the combine  10 .  
         [0040]    Many changes and modifications may be made to the invention without departing from the spirit thereof. The scope of some of these changes are discussed above. The scope of the remaining changes will become apparent from the appended claims.
A lighting system for an off-road vehicle includes one or more exit lights that are activated upon operator demand and that are automatically deactivated a designated period of time after exit lights activation, thereby facilitating the operator's departure from the vehicle. The lighting system includes an electrical power source, at least one running light, at least one exit light, and a control system that is coupled to the power source and to the lights and that controls operation of the running light and the exit light. The control system includes a manually operated switch movable between (1) an OFF position in which neither the running light nor the exit light is coupled to the power source, (2) a running light activation position in which at least the running light is coupled to the power source, and (3) an exit light activation position. A timer is operatively coupled to the switch and to the exit light and is operable, in response to selection of the exit light activation position of the switch, to couple the exit light to the power source for a designated period of time. Because exit light activation occurs under operator control rather than automatically, and because exit light activation is not necessarily preceded by running light deactivation or any other operation, the operator is imbued with a sense of control not experienced with other exit light control systems.