System and method for controlling power of a computer terminal with an external power source

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.

BACKGROUND

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.

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.

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

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.

DETAILED DESCRIPTION

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 inFIG. 1, an exemplary embodiment of a system100according to the present invention includes a host device/machine (e.g., a forklift105) which is coupled to a wireless computing terminal (e.g., a VRC205). Although the present invention will be described with respect to the forklift105and the VRC205, 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.

InFIG. 1, the forklift105includes an engine110(e.g., gas, oil, coal, etc.) connected to a battery115and an ignition switch120. Igniting the engine110of the forklift105may be accomplished in a similar manner to that of a conventional automobile. For example, when an operator of the forklift105turns the ignition switch120in a first direction (an “On” state), fuel via a fuel source (e.g., gas tank) and power via the battery115are continuously provided to the engine110. Then, a starter (e.g., button, switch, key) engages a starter motor to cause the engine110to begin running. When the operator turns the ignition switch120in a second direction (an “Off” state), the engine110may be shut down. As understood by those skilled in the art, the forklift105may further include an alternator118connected to the engine110and the battery115. The engine110powers the alternator118, which charges the battery115while the engine110is running. While in both the on and off states, one or more peripherals (e.g., lights, radio, etc.) may drain power from the battery115. Thus, when the engine110is in the off state, the battery115is no longer being charged and is susceptible to a complete drain by the peripheral(s) which is not shut off. The forklift105further includes one or more elements (e.g., a switched power rail125) 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.

The VRC205may be mounted on the forklift105by any conventional mechanism. For example, the VRC205may include a bracket (not shown) which may be fastened mechanically or chemically to the forklift105. Preferably, the VRC205is mounted on the forklift105at a location which is easily accessible and viewable by the operator when the forklift105is being operated. For example, the VRC205may be mounted on or near a control panel or a cockpit of the forklift105.

As shown inFIG. 1, the VRC205includes a processor210connected to a power arrangement215. In one exemplary embodiment, the power arrangement215includes a lead220and a backup battery225. The lead220is connected to the battery115of the forklift105. Thus, the VRC205may continually draw power from the battery115. The backup battery225(e.g., a NiMH battery) may provide power if the battery115of the forklift115becomes completely discharged. Preferably, the operator is notified when the VRC205is drawing power from the battery115and/or the backup battery225. For example, if the operator has shut down the engine110but forgotten to shut down the VRC205, the VRC205may completely discharge the battery115. However, the VRC205may remain operational by drawing power from the backup battery225. When the VRC205switches from the battery115to the backup battery225, the operator is notified, via an output arrangement (not shown) (e.g., LED indicator, alarm, pop-up window) of the VRC205.

The VRC205further includes a timer230which is connected to a voltage detector235and the processor210. The timer230may be further connected to the power arrangement215. Those of skill in the art will understand that the detector235may be connected to both the timer230, the processor210and/or the power arrangement215. According to the present invention, the detector235is connected to the rail125and detects at least the first and second voltage values thereon. Preferably, the connection to the rail125is robust, such that it may be maintained for all movements and actions of the forklift105. The connection to the rail125may 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.

Operation of the VRC205will be described with reference to an exemplary embodiment of a method300according to the present invention which is shown inFIG. 2. In operation, the operator may begin a shift (e.g., a predetermined time for which the forklift105will be used) by turning the ignition switch120to provide fuel and power to the engine110for running of the forklift105. As described above, the starter engages the starter motor which starts the engine110running. While running, the engine110drives the alternator118which charges the battery115.

In step305, the VRC205detects the first voltage value at the rail125utilizing the detector235. The detector235may 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 VRC205that the engine110is running. In one exemplary embodiment, the VRC205draws power from the battery115until the VRC205has been manually or automatically powered off. That is, the VRC205draws power from the battery115regardless 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 detector235may not measure the magnitude of the first voltage value but simply determine an existence thereof. In this embodiment, the detector235may act as a switch moving between states based on the voltage value(s), or lack thereof, at the rail125. The processor210may detect a change in the state of the detector235. However, if the magnitude of the first voltage value is obtained by the detector235, the VRC205may store the first voltage value for reasons which will be described below.

In another exemplary embodiment, upon detection of the first voltage value, the VRC205ceases drawing power from the backup battery225and begins drawing power from the battery115of the forklift105. For example, the backup battery225may sustain power to the VRC205while it is not being used and/or the engine110is not running. When the first voltage value is detected, the VRC205draws power from the battery115.

In step310, the VRC205resets the timer230. The timer230may be initialized with a predetermined time period set by the operator or pre-packaged with software executed by the processor210. The predetermined time period may be changed based on an amount of time for which the operator temporarily leaves the forklift105and shuts off the engine110. For example, after the operator drives the forklift105to a loading dock and loads items onto a delivery truck, he may temporarily leave the forklift105to 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 VRC205has detected the first voltage value (e.g., the engine110is running), the timer is maintained at the predetermined time period. The significance of the predetermined time period will be explained more fully below.

In step315, the VRC205draws power from the battery115of the forklift105. In the embodiment where the VRC205includes the backup battery225and the first voltage value has been detected, the VRC205draws power only from the battery115. As understood by those skill in the art, the VRC205may draw enough power to execute any application loaded thereon. Furthermore, the VRC205may draw additional power to charge the backup battery225. As understood by those of skill in the art, the timer230may be reset and the VRC205may begin drawing power from the battery115simultaneously.

In step320, the VRC205determines whether a predetermined voltage change (e.g., a voltage drop) has occurred at the rail125. As described above, the detector235may detect the voltage value(s) at the rail125while the VRC205remains powered. The voltage drop may occur when the first voltage value at the rail125decreases to a second voltage value. The voltage drop happens if, for example, the operator shuts off the engine110by turning the ignition switch120. A magnitude of the second voltage value may be zero or a negligible amount, either of which signifies to the VRC205that the engine110is 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 engine110is no longer running. If the voltage drop has not been detected (i.e., detector235detects the first voltage), the VRC205continues drawing power from the battery115.

In step325, the VRC205activates the timer230having 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 timer230may decrement from the initial value to zero, or may increment from zero to the final value. The timer230may be activated by the detector235or the processor210. That is, upon detection of the voltage drop, the detector235may activate the timer230. Or, the detector235may notify the processor235of the voltage drop and the processor210may activate the timer230.

In step330, the VRC205determines whether the first voltage value has been detected at the rail125. While the timer230is decrementing, the operator may have turned the engine110back on. For example, at the loading dock, the operator may have turned off the engine110and left the forklift105to assist loading the items into the delivery truck. When the operator turned off the engine110, the timer230was activated. Thus, the VRC205maintained drawing power from the battery115. However, because the predetermined time period of the timer230was set at fifteen minutes, the operator finished loading the items and restarted the engine110after, for example, only ten minutes. Thus, the VRC205remains powered without interrupting applications executing thereon or losing data, and the operator remains logged on to the server. Because, the VRC205remained connected to the server, the VRC205is 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 engine110is running again), then the VRC205resets the timer230and continues drawing power from the battery115.

In step335, because the first voltage value has not been detected, the VRC205determines whether the predetermined time period on the timer230has expired. If the predetermined time period has not expired, the timer230continues to decrement the predetermined time period, the VRC205continues drawing power from the battery115and continues detecting for the first voltage value at the rail125. In step340, the predetermined time period has expired, and, thus, the VRC205initiates a power-off procedure. That is, the VRC205ceases drawing power from the battery115. As noted above, the VRC205may switch to the backup battery225or may shut down completely (i.e., cease drawing power from the battery115and/or the battery backup battery225).

In one exemplary embodiment of the present invention, a display (e.g., LCD) of the VRC205shows the operator the predetermined time period. Thus, the operator is aware of a remaining time for which the VRC205is powered. In this manner, the VRC205may temporarily or permanently extend the predetermined time period after receiving an indication from the operator and/or the server that the VRC205should 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 VRC205must maintain power. The VRC205may 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 VRC205to remain powered in a similar situation. That is, the server may interrupt the data transmission from/to the VRC205to 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 VRC205shows that the battery115is almost completely discharged and any further draw therefrom would cause full discharge. The operator and/or server may further instruct the VRC205to power-off before the timer230has expired.

Although the present invention has been described with respect to the voltage detector235detecting the voltage at the rail125, another exemplary embodiment may include a mechanical detection mechanism to determine whether the engine110is running. For example, one or more limit switches and/or enclosed switches may be disposed at the ignition switch120. Thus, when the operator turns a key, flips a switch or presses a button, contact with the limit switch may indicate to the VRC205whether the engine110is running. Also, the detector235may detect a change in a current within the forklift105. For example, the detector235may be connected to a component of the forklift105which connects the alternator118to the battery115, and, when the engine110is running, the current is passing through the component.

Furthermore, although the present invention has been described with respect to the forklift105and the VRC205, the system100and method300may 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.

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 forklift105may include a motor which is powered by a rechargeable battery (e.g., 24 V DC battery). In this embodiment, the detector235may detect a voltage increase when the forklift105shut off. For example, an active load (e.g., powering forklift105and the VRC205) on the rechargeable battery will be greater than a rest load (e.g., only powering the VRC205). Thus, the VRC205may detect a voltage increase when the forklift105is shut off. The detection of the voltage increase may start the timer230.

AlthoughFIG. 1shows an exemplary embodiment of an architecture of the VRC205, those of skill in the art will understand that other configurations may be utilized. For example, in one embodiment, the detector235, via a direct connection, notifies the power arrangement215of when to begin drawing power from the battery115. In another embodiment, the timer230, via a further direct connection, notifies the power arrangement215of when to cease drawing power from the battery115. In yet a further embodiment, the timer230is implemented as a software application executed by the processor210. Thus, the timer230is not a stand-alone element of the VRC205.