Abstract:
Described is system and method for controlling power of a computing terminal with an external power source. In particular, a voltage is measured within a system using a voltage detector of a computing terminal. The system includes a battery which provides power to the system and the terminal. When the measured voltage changes to a first level, a first procedure is initiated to monitor the voltage for a time period. Upon expiration of the time period, if the monitored voltage has not changed to a second level, a second procedure is initiated to power off the terminal.

Description:
BACKGROUND  
       [0001]     Within a warehouse and/or factory environment, many wireless computing terminals (e.g., a barcode scanner) may be performing various functions at a single time. For example, a user may utilize the scanner to scan barcodes of items within the warehouse. The scanner includes wireless communication capabilities so that data (e.g., product data from barcodes) is transmitted to and received from a central server and/or database over a radio channel. Other computing terminals within the warehouse may also communicate over the radio channel. For example, a vehicle radio computer (“VRC”) is attached to a machine (e.g., a forklift). Similar to the scanner, the VRC includes a radio transceiver which allows an operator of the forklift to communicate with the server and/or database.  
         [0002]     In a conventional system, the VRC is mounted onto the forklift and connects to a battery thereof. The forklift also includes an internal combustion engine and an alternator. Thus, when the engine is running, the battery is being recharged via the alternator. On the other hand, if the engine is off, the battery is not being charged, and the VRC typically draws a large amount of power therefrom. If the operator of the forklift does not power-off the VRC after the engine has been shut off, the VRC drains the battery. Without any charge remaining on the battery, the engine cannot start, and thus the battery cannot be recharged. Consequently, the VRC may not be turned on. This represents a significant cost to a proprietor of the warehouse/factory, because the forklift and the VRC are inoperable for a period of time.  
         [0003]     One solution to this problem is to connect the VRC to an external relay box. When the operator turns the engine off, the relay box instantaneously cuts power to the VRC. Although the relay box prevents the VRC from draining the battery, other problems arise. For example, the operator typically shuts off the engine for only a short time (e.g., when temporarily leaving the forklift unmanned), and, as a result, the relay box cuts power to the VRC. Thus, only after restarting the engine, may the operator reboot the VRC and re-logon to the server. Furthermore, any applications of the VRC which were in the process of being executed may be interrupted, and/or any unsaved data may be lost. Thus, the proprietor of the warehouse/factory still faces a cost associated with a time taken by the operator to reboot the VRC and re-logon to the server.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention relates to a method which includes measuring a voltage within a system by a voltage detector of a computing terminal. The system includes a battery providing power to the system and the terminal. When the measured voltage drops to a first level, a first procedure is initiated to monitor the voltage for a time period. Upon expiration of the time period, if the monitored voltage has not increased to a second level, a second procedure is initiated to power off the terminal.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  shows an exemplary embodiment of a system according to the present invention; and  
         [0006]      FIG. 2  shows an exemplary embodiment of a method according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0007]     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. As shown in  FIG. 1 , an exemplary embodiment of a system  100  according to the present invention includes a host device/machine (e.g., a forklift  105 ) which is coupled to a wireless computing terminal (e.g., a VRC  205 ). Although the present invention will be described with respect to the forklift  105  and the VRC  205 , those of skill in the art will understand that any devices, machines and/or terminals which share a power source may utilize the present invention. In particular, the present invention may be utilized by a parasitic device/terminal which is connected to and derives power from the power source of the host device/machine.  
         [0008]     In  FIG. 1 , the forklift  105  includes an engine  110  (e.g., gas, oil, coal, etc.) connected to a battery  115  and an ignition switch  120 . Igniting the engine  110  of the forklift  105  may be accomplished in a similar manner to that of a conventional automobile. For example, when an operator of the forklift  105  turns the ignition switch  120  in a first direction (an “On” state), fuel via a fuel source (e.g., gas tank) and power via the battery  115  are continuously provided to the engine  110 . Then, a starter (e.g., button, switch, key) engages a starter motor to cause the engine  110  to begin running. When the operator turns the ignition switch  120  in a second direction (an “Off” state), the engine  110  may be shut down. As understood by those skill in the art, the forklift  105  may further include an alternator  118  connected to the engine  110  and the battery  115 . The engine  110  powers the alternator  118 , which charges the battery  115  while the engine  110  is running. While in both the on and off states, one or more peripherals (e.g., lights, radio, etc.) may drain power from the battery  115 . Thus, when the engine  110  is in the off state, the battery  115  is no longer being charged and is susceptible to a complete drain by the peripheral(s) which is not shut off. The forklift  105  further includes one or more elements (e.g., a switched power rail  125 ) which supplies power to one or more peripherals (e.g., headlights, radio, etc.) when the ignition switch is in the “On” state and removes power therefrom when the ignition switch is in the “Off” state.  
         [0009]     The VRC  205  may be mounted on the forklift  105  by any conventional mechanism. For example, the VRC  205  may include a bracket (not shown) which may be fastened mechanically or chemically to the forklift  105 . Preferably, the VRC  205  is mounted on the forklift  105  at a location which is easily accessible and viewable by the operator when the forklift  105  is being operated. For example, the VRC  205  may be mounted on or near a control panel or a cockpit of the forklift  105 .  
         [0010]     As shown in  FIG. 1 , the VRC  205  includes a processor  210  connected to a power arrangement  215 . In one exemplary embodiment, the power arrangement  215  includes a lead  220  and a backup battery  225 . The lead  220  is connected to the battery  115  of the forklift  105 . Thus, the VRC  205  may continually draw power from the battery  115 . The backup battery  225  (e.g., a NiMH battery) may provide power if the battery  115  of the forklift  115  becomes completely discharged. Preferably, the operator is notified when the VRC  205  is drawing power from the battery  115  and/or the backup battery  225 . For example, if the operator has shut down the engine  110  but forgotten to shut down the VRC  205 , the VRC  205  may completely discharge the battery  115 . However, the VRC  205  may remain operational by drawing power from the backup battery  225 . When the VRC  205  switches from the battery  115  to the backup battery  225 , the operator is notified, via an output arrangement (not shown) (e.g., LED indicator, alarm, pop-up window) of the VRC  205 .  
         [0011]     The VRC  205  further includes a timer  230  which is connected to a voltage detector  235  and the processor  210 . The timer  230  may be further connected to the power arrangement  235 . Those of skill in the art will understand that the detector  235  may be connected to both the timer  230 , the processor  210  and/or the power arrangement  215 . According to the present invention, the detector  235  is connected to the rail  125  and detects at least the first and second voltage values thereon. Preferably, the connection to the rail  125  is robust, such that it may be maintained for all movements and actions of the forklift  105 . The connection to the rail  125  may be a conducting wire which preferably includes an insulating sheath therearound. The sheath may be manufactured from any material which protects the wire from elements (e.g., weather, debris, dust, sparks, etc.) of an external environment.  
         [0012]     Operation of the VRC  205  will be described with reference to an exemplary embodiment of a method  300  according to the present invention which is shown in  FIG. 2 . In operation, the operator may begin a shift (e.g., a predetermined time for which the forklift  105  will be used) by turning the ignition switch  120  to provide fuel and power to the engine  110  for running of the forklift  105 . As described above, the starter engages the starter motor which starts the engine  110  running. While running, the engine  110  drives the alternator  118  which charges the battery  115 .  
         [0013]     In step  305 , the VRC  205  detects the first voltage value at the rail  125  utilizing the detector  235 . The detector  235  may detect for the first voltage value continuously or at predefined times (e.g., fixed intervals, upon powering-on, etc.). The first voltage value indicates to the VRC  205  that the engine  110  is running. In one exemplary embodiment, the VRC  205  draws power from the battery  115  until the VRC  205  has been manually or automatically powered off. That is, the VRC  205  draws power from the battery  115  regardless of a magnitude of the first voltage value. In this manner, the magnitude of the first voltage value may be relevant only to the extent that it is not zero. Thus, the detector  235  may not measure the magnitude of the first voltage value but simply determine an existence thereof. In this embodiment, the detector  235  may act as a switch moving between states based on the voltage value(s), or lack thereof, at the rail  125 . The processor  210  may detect a change in the state of the detector  235 . However, if the magnitude of the first voltage value is obtained by the detector  235 , the VRC  205  may store the first voltage value for reasons which will be described below.  
         [0014]     In another exemplary embodiment, upon detection of the first voltage value, the VRC  205  ceases drawing power from the backup battery  225  and begins drawing power from the battery  115  of the forklift  105 . For example, the backup battery  225  may sustain power to the VRC  205  while it is not being used and/or the engine  110  is not running. When the first voltage value is detected, the VRC  205  draws power from the battery  115 .  
         [0015]     In step  310 , the VRC  205  resets the timer  230 . The timer  230  may be initialized with a predetermined time period set by the operator or pre-packaged with software executed by the processor  210 . The predetermined time period may be changed based on an amount of time for which the operator temporarily leaves the forklift  105  and shuts off the engine  110 . For example, after the operator drives the forklift  105  to a loading dock and loads items onto a delivery truck, he may temporarily leave the forklift  105  to sign an invoice and/or aid in packing the items in the truck. The operator may routinely perform this activity, and, as such, may set the predetermined time period to a quantity slightly greater than the amount of time required therefore. Thus, if the activity routinely takes ten minutes, the predetermined time period may be set to fifteen minutes. In this embodiment, while the VRC  205  has detected the first voltage value (e.g., the engine  110  is running), the timer is maintained at the predetermined time period. The significance of the predetermined time period will be explained more fully below.  
         [0016]     In step  315 , the VRC  205  draws power from the battery  115  of the forklift  105 . In the embodiment where the VRC  205  includes the backup battery  225  and the first voltage value has been detected, the VRC  205  draws power only from the battery  115 . As understood by those skill in the art, the VRC  205  may draw enough power to execute any application loaded thereon. Furthermore, the VRC  205  may draw additional power to charge the backup battery  225 . As understood by those of skill in the art, the timer  230  may be reset and the VRC  205  may begin drawing power from the battery  115  simultaneously.  
         [0017]     In step  320 , the VRC  205  determines whether a predetermined voltage change (e.g., a voltage drop) has occurred at the rail  125 . As described above, the detector  235  may detect the voltage value(s) at the rail  125  while the VRC  205  remains powered. The voltage drop may occur when the first voltage value at the rail  125  decreases to a second voltage value. The voltage drop happens if, for example, the operator shuts off the engine  110  by turning the ignition switch  120 . A magnitude of the second voltage value may be zero or a negligible amount, either of which signifies to the VRC  205  that the engine  110  is no longer running. As understood by those of skill in the art, the predetermined voltage drop is an exemplary embodiment of any change in the first voltage value which indicates that the engine  110  is no longer running. If the voltage drop has not been detected (i.e., detector  235  detects the first voltage), the VRC  205  continues drawing power from the battery  115 .  
         [0018]     In step  325 , the VRC  205  activates the timer  230  having the predetermined time period beginning at an initial value and expiring at a final value. As understood by those of skill in the art, the timer  230  may decrement from the initial value to zero, or may increment from zero to the final value. The timer  230  may be activated by the detector  235  or the processor  210 . That is, upon detection of the voltage drop, the detector  235  may activate the timer  230 . Or, the detector  235  may notify the processor  235  of the voltage drop and the processor  235  may activate the timer  210 .  
         [0019]     In step  330 , the VRC  205  determines whether the first voltage value has been detected at the rail  125 . While the timer  230  is decrementing, the operator may have turned the engine  110  back on. For example, at the loading dock, the operator may have turned off the engine  110  and left the forklift  105  to assist loading the items into the delivery truck. When the operator turned off the engine  110 , the timer  230  was activated. Thus, the VRC  205  maintained drawing power from the battery  115 . However, because the predetermined time period of the timer  230  was set at fifteen minutes, the operator finished loading the items and restarted the engine  110  after, for example, only ten minutes. Thus, the VRC  205  remains powered without interrupting applications executing thereon or losing data, and the operator remains logged on to the server. Because, the VRC  205  remained connected to the server, the VRC  205  is capable of receiving wireless signals (e.g., instructions for subsequent tasks for the operator) from the server. If the first voltage value is detected (e.g., the engine  110  is running again), then the VRC  205  resets the timer  230  and continues drawing power from the battery  115 .  
         [0020]     In step  335 , because the first voltage value has not been detected, the VRC  205  determines whether the predetermined time period on the timer  230  has expired. If the predetermined time period has not expired, the timer  230  continues to decrement the predetermined time period, the VRC  205  continues drawing power from the battery  115  and continues detecting for the first voltage value at the rail  125 . In step  340 , the predetermined time period has expired, and, thus, the VRC  205  initiates a power-off procedure. That is, the VRC  205  ceases drawing power from the battery  115 . As noted above, the VRC  205  may switch to the backup battery  225  or may shut down completely (i.e., cease drawing power from the battery  115  and/or the battery backup battery  225 ).  
         [0021]     In one exemplary embodiment of the present invention, a display (e.g., LCD) of the VRC  205  shows the operator the predetermined time period. Thus, the operator is aware of a remaining time for which the VRC  205  is powered. In this manner, the VRC  205  may temporarily or permanently extend the predetermined time period after receiving an indication from the operator and/or the server that the VRC  205  should remain powered. For example, if the operator is transmitting data to the server when the predetermined time period is about to expire, the operator may indicate (e.g., press a button/portion of screen, etc.) that the VRC  205  must maintain power. The VRC  205  may then augment the remaining portion of the predetermined time period with a predetermined value which is, for example, chosen from increments (e.g., one minute, 10 minutes, etc.) or entered by the operator/server. The server may instruct the VRC  205  to remain powered in a similar situation. That is, the server may interrupt the data transmission from/to the VRC  205  to transmit an instruction to extend the predetermined time period. The operator may override the instruction from the server if, for example, the display of the VRC  205  shows that the battery  115  is almost completely discharged and any further draw therefrom would cause full discharge. The operator and/or server may further instruct the VRC  205  to power-off before the timer  230  has expired.  
         [0022]     Although the present invention has been described with respect to the voltage detector  235  detecting the voltage at the rail  125 , another exemplary embodiment may include a mechanical detection mechanism to determine whether the engine  110  is running. For example, one or more limit switches and/or enclosed switches may be disposed at the ignition switch  120 . Thus, when the operator turns a key, flips a switch or presses a button, contact with the limit switch may indicate to the VRC  205  whether the engine  110  is running. Also, the detector  235  may detect a change in a current within the forklift  105 . For example, the detector  235  may be connected to a component of the forklift  105  which connects the alternator  118  to the battery  115 , and, when the engine  110  is running, the current is passing through the component.  
         [0023]     Furthermore, although the present invention has been described with respect to the forklift  105  and the VRC  205 , the system  100  and method  300  may be utilized by further systems. For example, the present invention may be utilized by any device which draws power from a vehicle with an internal combustion engine. In one embodiment, a cradle for charging a battery of a handheld computer (e.g., cell phone, PDA, scanner, etc.) may draw power from the battery of the vehicle. The cradle may further power a non-computing device (e.g., a flashlight). In another embodiment, a vehicle-mounted peripheral (e.g., RFID reader) and/or a battery thereof may draw power from the battery of the vehicle. Thus, as described above, the present invention may be utilized by a parasitic device which derives power from the power source of the host device.  
         [0024]     In yet a further embodiment, the present invention may be utilized by a battery-powered vehicle that does not require a natural fuel (e.g., gasoline, oil, coal). For example, the forklift  105  may include a motor which is powered by a rechargeable battery (e.g., 24 V DC battery). In this embodiment, the detector  235  may detect a voltage increase when the forklift  105  shut off. For example, an active load (e.g., powering forklift  105  and the VRC  205 ) on the rechargeable battery will be greater than a rest load (e.g., only powering the VRC  205 ). Thus, the VRC  205  may detect a voltage increase when the forklift  105  is shut off. The detection of the voltage increase may start the timer  230 .  
         [0025]     Although  FIG. 1  shows an exemplary embodiment of an architecture of the VRC  205 , those of skill in the art will understand that other configurations may be utilized. For example, in one embodiment, the detector  235 , via a direct connection, notifies the power arrangement  215  of when to begin drawing power from the battery  115 . In another embodiment, the timer  230 , via a further direct connection, notifies the power arrangement  215  of when to cease drawing power from the battery  115 . In yet a further embodiment, the timer  230  is implemented as a software application executed by the processor  210 . Thus, the timer  230  is not a stand-alone element of the VRC  205 .  
         [0026]     It will be apparent to those skilled in the art that various modifications may be made in the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.