Abstract:
A switching mechanism for controlling vehicle headlights, turn signals, and emergency flashers includes a housing mounted on a control stock rigidly mounted to the vehicle steering column. The housing includes depressions for each of the functions, and light source and optical responsive switch on opposite sides of each depression, the light source being aimed at the optical switch whereby a light beam traverses the depression. A controller is responsive to interruption of the beam by the vehicle operator placing a finger in the depression to control the corresponding vehicle function. The mechanism includes an algorithm executable on a microprocessor for controlling the turn signal switching function. The microprocessor receives input signals from switches activated by the vehicle operator and a vehicle speed sensor, and based on the algorithm, the turn signal function is controlled.

Description:
The present application is a Continuation-In-Part of U.S. application Ser. No. 09/273,088 filed on Mar. 19, 1999, now U.S. Pat. No. 6,448,548, in the name of inventors Emil Doczy and Earl H. Whetstone assigned to the assignee of the present application. 

   BACKGROUND OF THE INVENTION 
   This invention relates to a vehicle signal control module and system for controlling the turn signal lamps, emergency flasher lamps, and high/low headlight beams of an automotive vehicle, and is particularly suited for heavy-duty vehicles such as buses and tractor-trailer combination vehicles. 
   Automotive vehicles, including heavy duty vehicles such as buses and tractor-trailer heavy duty combination vehicles, are equipped with turn signal control systems which include a stock projecting from the steering column which is operated by the vehicle operator to control switching to operate the vehicle turn signals. These switches are electromechanical devices and, in the case of heavy-duty trucks and buses used in congested areas, are operated multiple times daily and often wear out long before the vehicle wears out. Accordingly, it has become common, particularly with such heavy-duty vehicles, to provide aftermarket replacement controls for repair purposes, which are relatively expensive in component costs as well as vehicle down time. In addition to turn signals, modern vehicles are equipped with emergency flasher lights, which require a separate control, and are also equipped with high/low headlight beam controls, which are also separate from the turn signal and emergency flasher control switches. 
   In the case of heavy duty tractor-trailer combination vehicles and buses, the vehicle when effecting a turn must first pull out in a direction opposite the direction in which the turn is made and then effect the turn, all to permit the rear portion of the vehicle to pull smoothly around the corner. This pre-turn will cause a mechanically self-controlling switch to cancel the turn indicators prior to the actual turn or completion of the turn. Accordingly, turn signal control units used on heavy-duty vehicles are generally not self-canceling, as are the turn signal controls used on passenger cars and other smaller vehicles. The driver of a heavy vehicle tractor-trailer combination vehicle must remember to manually move the turn signal control stock back to the off position after the turn has been effected. 
   SUMMARY OF THE INVENTION 
   The present invention provides a multifunction control module for use on heavy-duty vehicles. The control module is in the form of a switching mechanism combined with a software algorithm to control the turn signal function on the vehicle. 
   According to the present invention, a switch housing is mounted on the end of a control stock which is rigidly mounted to the vehicle&#39;s steering column. Depressions or cavities are provided in the top, side and end edges of the housing and are sized to accommodate a finger of a human hand. A light source, such as a light emitting diode, emits a beam of infrared light which traverses the cavity of the depression. An optically responsive solid state switch is mounted on the opposite side of the cavity or depression from the light emitting diode and normally receives the beam from the diode. The light emitting diode and the optically responsive switch are connected to a microprocessor, which is responsive to the signal emitted by the switch when the beam of light is broken to actuate the turn signals. Accordingly, the operator of the vehicle merely inserts a finger in the corresponding depression or cavity to actuate the left or right turn signals. The signal remains on until the operator again places his finger in the depression or cavity to turn the signal off or is switched off by the microprocessor acting on vehicle speed information. A similar depression or cavity and switching arrangement is provided in the end of the housing to control the vehicle high/low beam head lamps, and a cavity is provided in the top of the housing to control the emergency flashers. Accordingly, these functions are controlled from a single stock and housing, which may be manufactured relatively inexpensively, and which requires no moving parts. Accordingly, the life of the unit is substantially indefinite. 

   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     These and other features of the present invention will become apparent from the following description, with reference to the accompanying drawings, in which: 
       FIG. 1  is a view in perspective of a switching mechanism made pursuant to the teachings of the present invention; 
       FIG. 2  is a top plan view, partly in section, of the switching mechanism illustrated in  FIG. 1 ; 
       FIG. 3  is a cross sectional view taken substantially along lines  3 — 3  of  FIG. 2 ; 
       FIG. 4  is an exploded view in perspective of the switching mechanism illustrated in  FIGS. 1-3 ; 
       FIG. 5  is an electrical schematic illustrating the manner in which the various components of the housing illustrated in  FIGS. 1 and 2  are electrically interconnected; and 
       FIGS. 6   a  and  6   b  are electrical schematic illustrations of the manner in which the output of the switching device illustrated in  FIGS. 1 and 2  controls various vehicle functions. 
       FIG. 7  is a flow chart illustrating one preferred embodiment of a turn signal control algorithm in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings, a vehicle signal module generally indicated by the numeral  10  includes a housing  12  which is rigidly mounted to a stock  14  by a fastener  16  which extends through the housing  12 , a flattened portion  18  of the stock  14  and a bottom cover member  20 . The stock  14  is rigidly mounted on the vehicle steering column. A printed circuit board  22  is mounted between the housing  12  and the cover member  20  to provide the necessary electrical connections within the housing  12  as will hereinafter be explained. The stock  14  is provided with an opening  24  to permit wires fed through the stock  14  to be connected to the circuit board  22 . 
   The housing  12  includes a side edge  26 , an opposite side edge  28  an end edge  30 , and a transverse surface  32  extending between the edges  26 ,  28  and  30 . The orientation of the various surfaces  26 - 32  is illustrated in  FIG. 1  in the positions which they assume when the stock  14  is installed on the aforementioned steering column (not shown). Depressions or cavities  34 ,  36  and  38  and  40  are provided in the top  32 , end  30  and transverse edges  26 - 28 , respectively. The depressions or cavities  34 - 40  are sized to accept a human finger. Holders  42 ,  44  support a conventional light emitting diode and an optically responsive solid state switch, respectively, on opposite sides of the depression  34 . Accordingly, a light beam emitted by the light emitting diode transverses the cavity  34  and is received by the optically responsive switch mounted in holder  44 . Accordingly, when the operator inserts a finger into the depression or cavity  34 , the beam transmitted by the light emitting diode in holder  42  and received by the solid state switch in holder  44  is interrupted. Similar holders  46  and  48 ;  50  and  52 ; and  54  and  56  are installed on opposite sides of the cavities  36 ,  38  and  40 , respectively. Accordingly, when a human finger is inserted in any of the cavities  34 - 40 , the corresponding light beam transmitted by the corresponding light emitting diode and received by the optically responsive solid state switch will be broken. 
   Referring now to  FIG. 5  which illustrates schematically the various electrical connections within the housing  12  provided by the circuit board  22 , connectors  58 ,  60  provide connections with the regulated vehicle voltage supply and ground, respectively. A light emitting diode  62  is connected between the power supply and ground through a bias resistor R 1 , and an optically responsive solid state switch  64  is connected between power supply and ground through a bias resistor R 2 . The light emitting diode  62  and switch  64  are installed in holders  42 ,  44 , and, as discussed above, the switch  64  responds to breaking of the beam provided by the light emitting diode  62  to change the state of the signal at left turn output terminal  66 . Similarly, light emitting diode  68  and optically responsive solid state switch  70  are connected between power and ground through bias resistors R 3  and R 4 , respectively, and are installed within holders  46  and  48  on opposite sides of the depression or cavity  36 . The switch  70  responds to an interruption of the light beam received from light emitting diode  68  to change the state of the signal at the output terminal  72 . Still another light emitting diode  74  and optically responsive solid state switch  76  are connected between power and ground through appropriate bias resistors R 5  and R 6 , respectively. The light emitting diode  74  and switch  76  are installed in holders  50  and  52  on opposite sides of the depression or cavity  38 . The switch  76  is responsive to interruption of the beam of light received from light emitting diode  74  to change the state of the signal at output terminal  78 . Light emitting diode  80  and optically responsive solid state switch  82  are connected between power and ground through appropriate bias resistors R 7  and R 8 . The light emitting diode  80  and switch  82  are installed in holders  54 ,  56  on opposite sides of the cavity or depression  40 . The switch  82  responds to interruption of the beam of light received from light emitting diode  80  to change the state of the signal at output terminal  84 . A light emitting diode  86  is connected between the power and ground through a bias resistor R 9  and is mounted on the housing  12  in an appropriate place (not shown) to provide an indication that power is being supplied to the housing. 
   Referring now to  FIGS. 6   a  and  6   b , a microprocessor generally indicated by the numeral  88  is connected to power through a conventional regulating and filtering circuit generally indicated by the numeral  90  and is also connected to ground as indicated at  92 . Input terminal  94  of microprocessor  88  is connected to terminal  66 , terminal  96  of microprocessor  88  is connected to terminal  72  input terminal  98  of microprocessor  88  is connected to terminal  78 , and input terminal  100  of microprocessor  88  is connected to terminal  84 . Each of the terminals  66 ,  72 ,  78  and  84  are connected to their corresponding input terminals of microprocessor  88  through appropriate voltage regulating filtering and protection circuitry generally indicated by the numeral  102 . The microprocessor  88  also has an input (not shown) connected to a signal representing vehicle speed from the multiplex data buss. 
   Output terminal  104  of microprocessor  88  is connected to a solid state switching device  106 , which is responsive to a change of state of terminal  104  to switch left turn signals connected to a terminal generally indicated at  108 . Output terminal  110  of microprocessor  88  is connected to solid state switching device  112 , which is responsive to a change of state of output terminal  110  to switch the right turn signals connected to terminal generally indicated by the numeral  114 . Output terminal  116  of microprocessor  88  is connected to a solid state switch  118  which is responsive to a change of state on terminal  116  to switch the vehicle head light beams from the high beam to the low beam (or vice versa) which are connected to terminal generally indicated by the numeral  120 . Output terminal  122  of microprocessor  88  is connected to solid state switching device  124  which is responsive to a change of state on terminal  122  to switch on or off the vehicle emergency flashers connected to a terminal generally indicated by the numeral  126 . 
   In operation, when the vehicle operator desires to signal a left turn, the operator places a finger in the cavity or depression  34 , thereby interrupting the beam between the light emitting diode  62  and the optically responsive solid state switch  64 . Accordingly, the signal at terminal  66  changes state and microprocessor  88  responds to this change of state (which is transmitted to the microprocessor through input terminal  94 ) to generate a signal switching the solid state switch  106  to turn on the left turn signals connected to terminal  108 . Microprocessor  88  is programmed to maintain the signal on output terminal  104  even after the operator removes his finger from cavity or depression  34 , whereupon the optically responsive solid state switch  64  switches back to its initial state, thus removing the signal from input terminal  94  of microprocessor  88 . Microprocessor  88  is programmed to turn off solid state switch  106  by changing the state on output terminal  104  if the vehicle operator again places his finger in the cavity  34  causing the terminal  94  to change state, and is also programmed to turn off the solid state switch  106  if the vehicle speed exceeds a predetermined level. When the vehicle operator desires to signal a right turn, the vehicle operator places a finger in the cavity  36  thereby causing optically responsive solid state switch  70  to signal microprocessor  88  to turn on solid state switch  112  to actuate the right turn signals connected to terminal  114 . Of course, the vehicle operator turns off the right turn signals by again placing the finger cavity  36  thereby signaling microprocessor  88  to turn solid state switch  112  off. The microprocessor is also programmed to turn off switch  112  when the vehicle speed attains a predetermined level and/or a predetermined time period has elapsed. It will be noted that the stock  14  is conveniently mounted the steering wheel so that the vehicle operator may place a finger in the cavity  34  or  36  without removing his hand from the wheel. This concept is such that the switch is totally independent of the vehicle steering column. It may be located in any location which is ergonomically desirable. 
   When the vehicle operator desires to switch the vehicle head lamps to high beam from low beam, the vehicle operator places a finger in the cavity  38 , thereby causing optically responsive solid state switch  76  to change the state on terminal  78  which signals microprocessor through input terminal  98  to change the state on output terminal  116  thereby switching the solid state switching device  118  to switch the head lights connected to terminal  120  to the high beams. The microprocessor  88  is programmed to maintain the signal on the terminal  116  even after the vehicle operator has removed his finger from cavity  38 . When the vehicle operator again places his finger in cavity  38 , the microprocessor  88  responds to the signal transmitted to input terminal  98  to switch solid state switch  118  back to its initial state, thereby switching the head lights from the high beams to the low beams. 
   When the vehicle operator desires to actuate the vehicle warning flashers, the vehicle operator places a finger or thumb in the cavity  40 , thereby causing the optically responsive solid state switch  82  to change the state on terminal  84 . This change of state is communicated to microprocessor  88  through input terminal  100 , which responds to change the state on output terminal  122 , causing the solid state switch  124  to switch on the emergency flashers  126 . These emergency flashers remain on after the vehicle operator removes his finger or thumb from cavity. When the vehicle operator again places his finger or thumb in cavity  40 , microprocessor  88  responds to the corresponding change of state on input terminal  100  to change the state of output terminal  122 , thereby switching off the solid state switch  124  to turn off the flashers connected to the terminal  126 . Microprocessor  88  is also programmed to turn off and/or prevent the turning on of the flashers connected to terminal  126  when the vehicle speed exceeds a predetermined level. 
   Microprocessor  88  can be integral with the signal module  10  or alternatively external to the signal module  10 . When external signal module  10  microprocessor  88  can be either a stand alone unit or part of a more comprehensive ECU (electronic control unit) controlling several of the vehicles electronic functions. Microprocessor  88  contains reusable memory in one of various forms well known in the art and is operable to execute the algorithms represented by the flow chart of  FIG. 7  to control the signal functions herein before described. 
   Turning to  FIG. 7 , the algorithm  200  for turn signal operation will be described. Although only one circuit is shown, it should be understood that separate circuits are provided for the left and right turn signals. Turn signal control will be described from the perspective of the left turn signal. 
   Upon application of power, the microprocessor loads turn signal timeout and maximum speed constants into memory. Also on power on, microprocessor  88  signals switch  106  to turn the left turn signal off as instructed by the algorithm at step S 202 . At step, S 204  the microprocessor  88  is instructed to test for a left turn signal request from the vehicle operator. If a left turn signal request is found, the algorithm instructs the microprocessor to signal switch  106  turning on the left turn signal. Execution continues at step S 208  where a timer is started to monitor the length of time that the turn signal has been on. At step S 210 , microprocessor  88  is operable to compare the timer value to the timeout constant. 
   If the timer value is found to exceed the time out constant, the algorithm transfers control back to step S 202  turning off the turn signal and started a new turn signal monitoring cycle. If the timer value has not exceeded the time out constant at step S 210 , processing continues to step S 212 . At step S 212 , the algorithm instructs the microprocessor  88  to read the vehicle speed signal from a vehicle speed sensor (not shown) which is of known construction to those skilled in the art. The algorithm instructs microprocessor  88  to compare the vehicle speed with the maximum speed constant. If the algorithm determines that the vehicle speed is not less than the maximum speed constant, execution continues at step S 214 . At S 214 , the algorithm makes an additional check to be certain that the operator has not manually cancelled the turn signal. If there is no request from the operator to cancel the turn signal, control is transferred to step S 210  where a comparison of the turn signal activation time to the pre-determined time out constant is repeated. If at step S 214  it is found that the vehicle operator has manually turned off the turn signal, control is transferred back to step S 202  where the turn signal is turned off. 
   Returning to step S 212 , if the vehicle speed is determined by the algorithm to be less than the vehicle speed constant, processing continues to step S 216  where the turn signal is latched on which means that the operation of the turn signal is now controlled only by the vehicle speed, that is, activation time is no longer considered. At step S 218 , another speed comparison is made. If the vehicle speed is now greater than the maximum speed constant, control is transferred back to step S 202  where the turn signal is turned off and the cycle is repeated. If at step S 218  the vehicle speed has not exceeded the maximum speed constant value, processing continues at step S 220  where another test for input from the operator is made. At step S 220 , a test is made for manual cancellation of the turn signal. If at step S 220 , it is determined that the vehicle operator wants to manually cancel the turn signal, control is transferred back to step S 202  where the turn signal is turned off and the cycle is restarted. 
   If at step S 220  there is no input from the operator to manually cancel the turn signal, control is transferred back to step S 216  where the signal at switch  106  is maintained and the turn signal is kept on. The algorithm then repetitively executes steps S 216 , S 218 , and S 220  until either the turn signal is manually cancelled or the vehicle speed exceeds the turn signal maximum speed constant. 
   It should be understood from the discussion above that the processor advantageously prevents leaving the turn signal on. This is done through the steps S 210  and S 218 , where the processor queries whether the turn signal is timed out, or whether the speed has exceeded 15 mph, in either event, the signal is canceled.