Abstract:
An electrically powered vehicular device, such as a police radar detector, having an automatic reduced power feature, is disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims priority of U.S. provisional patent application, serial No. 60/377,142, filed May 2, 2002. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention relates to an electrically powered vehicular device, such as a police radar detector, having an automatic power reduction feature.  
         BACKGROUND OF THE INVENTION  
         [0003]    There are many electrically powered devices for communication and/or navigation, which are used today in vehicles, such as automobiles and boats. These devices typically operate from the vehicle&#39;s 12 volt electrical system via the vehicle&#39;s cigarette lighter socket. In many vehicles, power is available at the socket, even when the vehicle is turned off. Thus, if the device is not separately turned off when the vehicle is turned off, the device will continue to drain power from the vehicle&#39;s battery. If this occurs for an extended period of time, or if the battery otherwise has a low charge level, the device can drain power from the battery to a level where the vehicle will be unable to start.  
           [0004]    This invention is directed to solving these and other problems.  
         SUMMARY OF THE INVENTION  
         [0005]    It is an object of the invention to provide for a vehicle having an electrical system and a source of DC power coupled to the electrical system, an electrically powered vehicular device with an automatic power reduction feature.  
           [0006]    In accordance with the invention, the device comprises means for connecting the device to the source of DC power, means coupled to the connecting means for sensing whether the vehicle is turned on or off, and limiting means responsive to the sensing means for turning the device to a reduced power mode when the sensing means determines the vehicle is turned off.  
           [0007]    It is contemplated that the reduced power mode is off, or alternatively a stand-by mode.  
           [0008]    It is further contemplated that the sensing means includes means for monitoring background noise of the DC power; and means responsive to the monitoring means for determining that the vehicle is off if the background noise remains substantially constant over a period of time.  
           [0009]    Alternatively it is contemplated that the sensing means includes means for sensing a voltage level of the DC power and means for monitoring a characteristic of the background noise of the DC power, and means responsive to the sensing means and the monitoring means for turning the device to reduced power mode when the sensed voltage level and the background noise characteristic each reach a set threshold.  
           [0010]    It is yet further contemplated that the device includes means for over-riding the limiting means to permit the device to operate when the vehicle is turned off.  
           [0011]    Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a block diagram of a device in accordance with the invention.  
         [0013]    [0013]FIG. 2 is a logic flow chart of one part of the operation of the device of FIG. 1.  
         [0014]    [0014]FIG. 3 is a logic flow chart of another part of the operation of the device of FIG. 1.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiment illustrated.  
         [0016]    An electrically powered device  10  with automatic power reduction for use with a vehicle (not shown) is illustrated in FIG. 1. The device  10  may be a radar detector, a radio, such as a two way radio, a GPS receiver, or the like. The vehicle has an electrical system and a DC power source  12 , such as a conventional cigarette lighter outlet, coupled to the electrical system.  
         [0017]    The device  10  includes a power cord  16  for connecting the device  10  to the DC power source  12 . The device  10  includes a circuit  15 , coupled to the power cord  16 . Alternatively, the circuit  15  may be located within a separate power cord for interchangeable use with different devices.  
         [0018]    For a vehicle having a conventional 12 volt DC power system, the voltage level at its DC power source  12 , when the vehicle is running with its alternator/generator charging, is typically above 13 volts, while the voltage level of a vehicle that is not running is typically about 12 volts. Similarly, the electrical noise of a vehicle that is running is typically varying, while the electrical noise of a vehicle that is not running is typically rather constant.  
         [0019]    The device  10  continuously monitors the voltage level and the electrical noise at the DC power source  12 . The device  10  uses a threshold voltage level of 13.05 volts. When the voltage goes below the threshold, a voltage level timer is initiated. Once the voltage level timer reaches five minutes, and if the electrical noise is considered to be constant (+/−10%), a noise level timer is initiated. Once the noise level timer is initiated, if the voltage level remains below the threshold, and the noise level timer reaches 25 minutes, the circuit  15  will power down the device  10 . If at any time the voltage level equals or exceeds the threshold, the voltage level timer and the electrical noise timer will be reset, and the process will begin again. If at any time the electrical noise becomes variable, the electrical noise timer will be reset. In other words, for power down to occur, the voltage level must remain below the threshold for a 30 minute period and the electrical noise must remain constant for the last 25 minutes of the 30 minute period. It should be understood that the actual time periods can be varied, without departing from the invention.  
         [0020]    The circuit  15  of the device  10  is typically a microprocessor based product, having registers acting as the respective voltage level timer and electrical noise timer. Operation of the microprocessor with respect to the invention is discussed below with respect to FIGS. 2 and 3.  
         [0021]    Referring to FIG. 2, monitoring circuitry  20  monitors the voltage level at the DC power source  12 . Initially, if the microprocessor determines the voltage level is not less than 13.05 volts, the voltage level register is reset, and the microprocessor returns. If the microprocessor determines the voltage level is less than 13.05 volts, the voltage level timer register is incremented, and the microprocessor determines whether the voltage level timer register has reached 5 minutes. If not, the microprocessor returns. If it has reached 5 minutes, a voltage timer flag is set to True, to be discussed below with respect to FIG. 3.  
         [0022]    Referring to FIG. 3, the monitoring circuitry monitors the electrical noise at the DC power source  12 . Measurement of electrical noise is likewise described in co-owned application Ser. No. 10/040,907, which is incorporated by reference. If the microprocessor determines the electrical noise is not constant, the noise timer register is reset, and the microprocessor returns. If the microprocessor determines the electrical noise is constant, the noise timer register is incremented, and the microprocessor determines if the voltage timer flag is True. If not, the noise timer register is reset and the microprocessor returns.  
         [0023]    If the voltage timer flag is True, the microprocessor determines if the noise timer register has reached 25 minutes. If not, the microprocessor returns. However, if the noise timer register has reached 25 minutes, the microprocessor powers down the device  10 .  
         [0024]    Similarly, if used with a device having GPS capability, the monitoring circuitry  20  can determine whether the vehicle is moving or not, and from that information over a period of time, make a decision that the vehicle is not running.  
         [0025]    The device  10  further includes over-riding circuitry  26  for over-riding the circuit  15  to permit the device  10  to operate when the circuit  15  has determined that the vehicle is not running.  
         [0026]    While the specific embodiment has been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying Claims.