Abstract:
An electronic drive system using a plurality of drive circuits for enabling greater plurality of functions by selectively placing drive signals on the driver outputs at one of two possible polarities. At least one of the enabled functions taking a substantially shorter time for enablement, thereby allowing at least two of the plurality of functions to share a common driver output enabling signal.

Description:
PRIORITY CLAIM  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/526,838, filed on Dec. 4, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to a multiple function electronic drive system, and more particularly to a system that uses a reduced number of drive circuits to perform multiple functions.  
       BACKGROUND OF THE INVENTION  
       [0003]     Drive circuits are used extensively in automotive and industrial applications for switching power to ground referred loads. For example, in an automotive application, in order to actuate the power lift gate and the rear window defroster in a vehicle, an electronic drive system having a number of drive circuits is required. Currently, two drive circuits are used to enable the two functions of the lift gate and a separate drive circuit is used to enable the function of the rear window defroster. In this case, the two functions of the lift gate include a locking and unlocking function, while the function of the rear window defroster includes a heating function. Altogether, three drive circuits are used to enable the three different functions. With this configuration, enabling the functions of the lift gate and the rear window defroster can be performed independently. However, using separate drive circuits for enabling the three functions can be costly for such applications.  
         [0004]     Therefore, there is a need for an electronic drive system that uses a plurality of drive circuits to enable a plurality of functions, wherein the plurality of drive circuits is less than the plurality of functions. In addition, there is a need for an electronic drive system that can enable any one of the plurality of the functions and have negligible effect on the remaining ones of the functions.  
       SUMMARY OF THE INVENTION  
       [0005]     In one aspect of the invention, a method for enabling a first plurality of functions via electrical signals provides a second plurality of drive circuits for providing the electrical signals, wherein the second plurality is less than the first plurality. The functions are selected such that at least one of the functions can be enabled faster than at least one other function. At least one of the drive circuits is used to enable both the at least one function and the at least one other function.  
         [0006]     In another aspect of the invention, a driver system for enabling a first plurality of functions includes a second plurality of driver circuits, each operative to generate at an output thereof one of two possible signal polarities depending on a state of the driver circuits. A controller is operative to recognize requests for enabling at least one of the plurality of functions and to place the second plurality of driver circuits in states such that the driver circuit outputs will have appropriate signal polarities for enabling the at least one function requested. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0008]      FIG. 1  illustrates a multiple function electronic drive system according to the present invention; and  
         [0009]      FIG. 2  is a table showing a combination of polarity arrangements for the drive circuits according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0010]     The following description is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0011]      FIG. 1  illustrates a multiple function electronic drive system  10  for driving a number of functions using a number of drive circuits, wherein the number of drive circuits is less than the number of functions. The system  10  generally comprises an electronic configuration  12  having a power source  14  such as a battery, a microprocessor  16 , and two drive circuits  18   a,    18   b.  The power source  14  is coupled to the microprocessor  16  and the drive circuits  18   a,    18   b  for generating a flow of current through the drivers  18   a,    18   b.  In this example, a solenoid  20  and a heating element  22  are electrically coupled to the drivers  18   a,    18   b.  The solenoid  20  is essentially an electromagnet adapted to move an integral plunger in one of two directions depending upon the direction of current flow through its coil. The heating element  22  is made of a resistive conductor. Specifically, ends of the coil of solenoid  20  are respectively electrically coupled to one of the drivers  18   a,    18   b.  The heating element  22  is electrically coupled between driver  18   a  and ground. Alternatively, heating element  22  could be coupled between driver  18   b  and ground. The drive circuits  18   a,    18   b  may each comprise an electromechanical relay switch adapted to open and close, thereby changing the polarity at the potential appearing at the output of each drive circuit  18   a,    18   b.  It should be understood that the solenoid  20  can be replaced with any type of switch device such as, for example, a reversible motor.  
         [0012]     The drive circuits  18   a,    18   b  are controlled by the microprocessor  16 . It should be understood that the microprocessor  16  can be any type of commercially available microprocessor well known in the art for executing instructions. The microprocessor  16  controls the drive circuits  18   a,    18   b  by energizing and de-energizing the relay&#39;s coils, thereby closing and opening the power source contact of each relay and controlling the electrical current flow through the loads  20  and  22 . The electrical current is provided by the power source  14 . Specifically, the microprocessor  16  is used to reverse the polarities of the potential at the outputs of the drive circuits  18   a,    18   b,  thereby controlling the functions of the solenoid  20  and the heating element  22 . A user in a vehicle typically activates the microprocessor  16  to control the drive circuits  18   a,    18   b  states by command buttons that may be located in different areas of a vehicle. The drive circuits  18   a,    18   b  are used to enable the functions of the solenoid  20  and the heating element  22 . In this case, the movable plunger of solenoid  20  moves in a first or a second direction depending on the direction of current supplied by drive circuits  18   a,    18   b.    
         [0013]     The plunger of solenoid  20  is used to move a vehicle door&#39;s lock mechanism to locked or unlocked states. As such, when driver  18   a  is closed and driver  18   b  is open, the solenoid plunger moves an associated lock mechanism in a direction locking the door. When the polarities of the voltages at the outputs of the drivers  18   a,    18   b  are reversed, having driver  18   a  open and driver  18   b  closed, the solenoid plunger moves the associated lock mechanism in a second direction unlocking the door. When the drivers  18   a,    18   b  are both open, the solenoid  20  is off, thereby keeping the lock state of the door unchanged. In this case, no current is flowing through the solenoid  20 . Once the door is locked or unlocked, the drivers  18   a,    18   b  are switched back into their off state.  
         [0014]     The heating element  22  can also be actuated by the drivers  18   a,    18   b  to either an on or off state. The heating element  22  is used to generate heat for a vehicle side mirror defroster system. The heating element  22  can be actuated in two ways. The first is by operating driver relay  18   a  and opening driver  18   b.  The second is by operating both driver relays  18   a,    18   b.    
         [0015]     In a first example, when the user wishes to lock the door in the vehicle, the microprocessor  16  operates relay driver  18   a  and keeps relay driver  18   b  off. In doing so, the power source  14  provides a flow of current through driver  18   a  to ground, via the solenoid  20 . At this time, current also flows through the heating element  22  to ground. However, when the solenoid  20  is being actuated to lock the door, there is negligible effect on the heating element  22 . This is due to the difference between the length of time it takes to move the plunger of solenoid  20  in the locking direction and the time it takes to bring element  22  up to a desired temperature. The solenoid  20  is actuated within approximately 500 milliseconds to lock or unlock the door, while the heating element  22  requires approximately 10 seconds to begin generating heat. Since the solenoid  20  is actuated within approximately 500 milliseconds and the heating element  22  is actuated within approximately 10 seconds, the heating element  22  only gets activated for a short period of time, which is not long enough for the heating element  22  to begin generating heat. Once the solenoid  20  is actuated by closing driver  18   a  and opening driver  18   b,  the drivers  18   a,    18   b  are immediately placed in an off state, thereby releasing the solenoid  20 . As such, the heating element  22  is not energized long enough to begin generating heat.  
         [0016]     In a second example, when the user wishes to unlock the door in the vehicle, the microprocessor  16  closes driver  18   b  and leaves driver  18   a  open. In doing so, the power source  14  provides a flow of current through the solenoid  20  to move its plunger in a second direction, thereby unlocking the door. With this configuration, current flows through driver  18   b  to ground, via the solenoid  20 , unlocking the door in the vehicle. In this case, current is not flowing through heating element  22  because driver  18   a  is open thereby placing ground at both sides of element  22 . Once the solenoid  20  is operated to unlock the door, drivers  18   a,    18   b  are placed back into an off state, thereby turning the solenoid  20  off.  
         [0017]     Various methods can be used to enable the solenoid  20  to either lock or unlock the door. For example, the user can manually lock or unlock the door from command buttons located inside the vehicle. The user may also use a key or a keyless entry remote controller to lock or unlock the door.  
         [0018]     In a third example, when the user desires to turn the heating element  22  on, the microprocessor  16  applies the same potential across the relay coils of drive circuits  18   a,    18   b  to operate both drivers. In doing so, the power source  14  provides a flow of current through the driver  18   a  to heating element  22 , enabling the heating element  22  to begin generating heat. With this configuration, current flows through driver  18   a  and element  22  to ground. No current is flowing through the solenoid  20  at this time since the same potential from source  14  appears at both sides of the solenoid&#39;s coil.  
         [0019]     The microprocessor  16  switches the drivers  18   a,    18   b  back to their off position after the solenoid  20  is turned on. As for heating element  22 , the microprocessor  16  keeps the drivers  18   a,    18   b  in a closed state until the user decides to turn the heating element  22  off. As the heating element  22  is being activated, there is no effect on the solenoid  20 .  
         [0020]      FIG. 2  illustrates a table showing a combination of polarity arrangements for driver circuits  18   a,    18   b  and the resulting effect of each combination of relay driver states. Specifically, the effects include the functions of the solenoid  20  and/or the heating element  22 . The combinations are shown as 0s, which represent an off state, and 1s, which represent an on state. When the combination is 00, drivers  18   a,    18   b,  respectively, are off, thereby placing ground potential at the driver outputs. As such, no current is flowing through the solenoid  20  or the heating element  22 . This is referred to as a NO FUNCTION effect. When the combination is 01, driver  18   a  is off and driver  18   b  is on, thereby moving the plunger at solenoid  20  in an unlocking direction. This is referred to as an UNLOCK effect. When the combination is 10, driver  18   a  is on and driver  18   b  is off. This combination moves the plunger of solenoid  20  in a locking direction for the door and actuating the heating element  22 . This is referred to as a LOCK and HEAT effect. When the state combination is 11, the drivers  18   a,    18   b  are respectively closed. In this case, drivers  18   a,    18   b  have a positive polarity. As such, only the heating element  22  is enabled. The solenoid  20  remains at its off state since no current flows through its coil. It should be understood that as the heating element  22  is generating heat or as the drivers  18   a,    18   b  remain in a closed state, there is no effect on the solenoid  20 .  
         [0021]     In a fourth example, when the user wishes to lock or unlock the door and then turn on the side mirror defroster, the microprocessor  16  switches the polarities of the outputs of drivers  18   a,    18   b  in a combination of polarity arrangements to enable the functions of both the solenoid  20  and the heating element  22 . Initially, the microprocessor  16  has the drivers  18   a,    18   b  off, thereby placing the solenoid  20  and the heating element  22  to a NO FUNCTION effect (00). The microprocessor  16  then sets the polarity of each driver output to operate the plunger of solenoid  20  to either a LOCK or UNLOCK state, accordingly, depending on the user&#39;s decision. Within approximately 500 milliseconds, the microprocessor  16  operates each of the drivers  18   a,    18   b,  thereby enabling the heating element  22  to begin generating heat. The drivers  18   a,    18   b  remain closed until the user wishes to turn the side mirror defroster off.  
         [0022]     In another aspect of the fourth example, when the user wishes to turn the side mirror defroster on before locking or unlocking the door, the microprocessor  16  operates the relay drivers  18   a,    18   b,  thereby enabling the heating element  22  to begin generating heat. The drivers  18   a,    18   b  remain in an on state until the user wishes to lock or unlock the door. If the user decides to lock or unlock the door in the middle of heating up the heating element  22 , the polarity of the outputs of drivers  18   a,    18   b  are quickly changed to lock or unlock the door. Once the solenoid  20  operates to lock or unlock the door, the drivers  18   a,    18   b  are quickly positioned back into an on state, thereby providing current back to the heating element  22 . The transition between enabling the function of the heating element  22  to enabling one of the functions of the solenoid  20  and back to enabling the function of the heating element  22  is quick enough that there is a negligible effect on either function.  
         [0023]     It should be understood that the heating element  22  can be used to heat up any type of mechanism, such as, for example, a rear window defroster or the seats in the vehicle. The heating element  22  can also be replaced with any type of mechanism, such as, for example, a diode or another drive circuit. It should also be understood that the functions of the solenoid  20  can be extendable to other functions such as, for example, opening and closing a power sliding door or a power window of the vehicle.  
         [0024]     The present invention requires only two drive circuits to enable the two functions of the solenoid  20  and the function of the heating element  22 . This eliminates the need for an additional drive circuit to drive the heating element  22  independently. As such, cost of production is decreased.  
         [0025]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.